3. Research 3.1 Theses

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3. Research 3.1 Theses The following Theses have been completed at the FunMat laboratories by the end of March, 2010.

Electrical Characterization of Organic Memories using Polarizable Nanoparticles

Baral, Jayanta Kumar Åbo Akademi University, Faculty of Mathematics and Natural Sciences, Department of Physics Defence on June 16th, 2009 Opponent: Manish Chhowalla, Rutgers, the state university of New Jersey

Organic memory is an emerging field of organic electronics. We have demonstrated a solution processable memory device where an organic nanocomposite solution comprising of a fullerene derivative [6,6]–phenyl C61 butyric acid methyl ester (PCBM)–based nanoclusters dispersed in an insulating polystyrene matrix sandwiched between two metal Aluminum electrodes. The devices show an initial high resistive (OFF) state which, upon reaching a certain threshold voltage, permanently switches to a low resistive (ON) state. The threshold voltage is found to be ~3.5V, independent of the sample thickness; a property ideal for printed electronics. After the threshold voltage, the ON state current follows by a negative differential resistance (NDR) state in the current voltage characteristics of the devices. We have clarified the role of the nanocomposite film, and shown that tunneling is the reason for current conduction for both before and after the threshold voltage [1]. When adding higher concentration of nanoparticles, they start to aggregate, and form spherical like aggregates, that changes the device behavior from a poor insulator (high resistance) until it forms a conducting pathway (ohmic behavior) [2]. To clarify the underlying principle of such device behaviour, we have suggested a mechanism, i.e. dielectric breakdown due to polarizable nanoparticles inside the insulating polymer matrix [2]. This mechanism of dielectric breakdown inside the insulating medium explains the origin for the threshold jump from low–conductivity OFF to high–conductivity ON state of the device. The effect of NDR behaviour in these devices could be explained by a tunneling process between the polarisable PCBM nanoclusters inside the insulating polymer PS matrix. We have been able to identify this model by establishing the correlation between the morphology and electrical performance of these memory devices. This, in turn, leads to the possibility of improving upon the device performance and achieve the goal of memory elements for printed electronics.

References:

1. J. K. Baral, H. S. Majumdar, A. Laiho, H. Jiang, E. I. Kauppinen, R. H. A. Ras, J. Ruokolainen, O. Ikkala, and R. Österbacka, Nanotechnology 19, (2008) 035203‐035209.

2. A. Laiho, H. S. Majumdar, J. K. Baral, F. Jansson, R. Österbacka, and O. Ikkala, Applied Physics Letter 93, (2008) 203309‐203311.

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A sol‐gel derived adhesive for industrial use Puputti, Janne Åbo Akademi University, Faculty of Mathematics and Natural Sciences, Department of Physical Chemistry Defence on December 11th, 2009 Opponent: Assistant Professor Freddy Kleitz, Université Laval, Quebec, Canada

A new type of inorganic binder which is environmentally friendly and more thermally stable than present organic binders is investigated in this work. An amorphous silicate mineral was used as starting material for the sol‐gel based synthesis. This could be an interesting alternative for the large scale production of inorganic adhesives within, for example, the stone wool industry, in which the use of expensive metal alkoxide precursors is not economically feasible. Materials used for the preparation of the sol‐gel based binder were water, formic acid, lactic acid, citric acid, ethanol, and amorphous silicate mineral.

The results show that the gel mainly consists of silica while the other cations were dissolved in the pore liquid. The stability of the sols is strongly dependent on the pH of the solution, the longest gel times were obtained within the pH range of 2‐3. During the drying of the wet gels, organic salts of these cations were crystallized in the pores and transformed to oxides or carbonates during heating. A pronounced decrease in the extent of crystallization in dried gels was observed in samples containing citric acid or lactic acid. This is assumed to be due to the complexation behavior occurring in the solutions. The derived binder shows good wetting properties against mineral fiber surfaces and a good strength of paper‐binder composites. It was found that the addition of ethanol into the sol increased the gel time, as did the addition of citric acid or lactic acid. The different constituents of the raw material play a major role during the drying and heat treatment of the gels. It is shown that due to the soluble metal carboxylates, a post‐treatment at 400oC or higher is needed in order to achieve full binder stability under excess of water. Furthermore, mesoporous gels can be made hydrophobic by post‐treatments with either silanes or organophosphonates, showing that both silica and metal oxides are exposed on the surface of the binder. Surface functionalization is especially effective for gels heat‐treated at high temperatures where the metal carboxylates decompose to the corresponding oxides or carbonates. It is also possible to use the sol basing on the inorganic amorphous silicate for synthesizing mesoporous materials under acidic conditions. Syntheses of two different tri‐block‐co‐polymer templated silicas, SBA‐15 and KIT‐5, are described in this work.

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Silicon releasing sol‐gel TiO2‐SiO2 thin films for implant coatings Ääritalo, Virpi Åbo Akademi University, Faculty of Chemical Engineering, Laboratory of Polymer Technology Defence on December 11th, 2009 Opponent: Professor Serena Best The formation of a bond between biological tissue and implant material is an essential demand in many medical biomaterial applications. The lack of appropriate cell response often leads to the encapsulation of implant from the surrounding tissue, which furthermore inhibits the bonding of implant to tissue e.g. in bone applications. The biological performance of inert biomaterial surfaces can be improved by a bioactive coating, which forms the tight bond with surrounding tissue. TiO2–SiO2 mixed oxide coatings are promising alternative for enhancing the tissue contact of implant materials. The sol–gel TiO2 is shown to be bioactive and biocompatible, but the biological performance of coating can be enhanced by addition of SiO2 into the material, as the silicon is shown to have positive effect on osteoblast response on medical implant surfaces.

In the present work the coatings were prepared by sol–gel method, which is a widely used preparation technique of different metal oxides for catalytic and optical applications. The TiO2 and TiO2–SiO2 coatings with different amount of silica were prepared by carefully controlling the process parameters (e.g. Ti to Si ratio, acid catalyst concentration, prehydrolysis, sol ageing). The aim of the study was to achieve silica–releasing surfaces with suitable chemistry and nanotopography conferring bioactive coating. The surfaces were carefully characterized, in vitro behavior and silicon release were monitored in simulated body fluid (SBF) or in phosphate buffer. The photocatalytic test was adopted as a analytical tool for medical sol–gel coatings, as it is well known that the crystal properties, surface area and porosity are all having an influence on the photocatalytic activity as well as on bioactivity of the sol–gel materials. A series of coatings was evaluated in fibroblast and osteoblast cell cultures. In addition, a NiTi suture material was coated with a TiO2–SiO2 coating manufactured at lower temperature by autoclaving instead of heat–treatment in oven at 500oC. This low–temperature coating was tested in animal experiment as an implant coating on NiTi suture.

The sol–gel TiO2–SiO2 coatings easily form a heterogeneous structure where the TiO2 and SiO2 particles are partly interconnected and covered with soluble silicon. The silicon release and surface nanotopography of the films can be tailored by varying the sol–gel processing parameters. The formed nanotopography of TiO2–SiO2 coatings was suitable for biological applications. The silica containing TiO2–SiO2 sol–gel films endow with enhanced osteoblast activity compared with pure titania coating, which likely will improve the bone bonding properties of the coatings. Furthermore, the coatings had good fibroblast cell response, indicating the biocompatibility of the films. Low–temperature TiO2–SiO2 sol–gel films were successfully prepared by autoclaving dip–coated films. The encouraging results from animal tests with coated NITI suture suggest that the low–temperature autoclaved film having 10 mol% of silica can be a valuable alternative for conventional high temperature sol–gel implant coatings for temperature sensitive substrates.

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3.2 Projects

3.2.1 Synthesis of functional inorganic particles and formulation of dispersions. Professor Jarl B. Rosenholm and Associate professor Mika Lindén

The main responsibilities can be summarized as follows: a) to synthesize functional nanoparticles, b) to surface functionalize the particles in desired ways, c) to prepare stable, printable dispersions of either nanoparticles synthesized in‐house or of commercially available particles. Both aqueous and organic dispersions are of interest, as different printing techniques have different requirements in terms of the solvent properties. During the year we have synthesized and thoroughly characterized a wide range of both porous and non‐porous nanoparticles, including SiO2, TiO2, SiO2/Fe3O4, and Mn2O3. All of these particles are available in particle sizes < 100 nm and as stable aqueous dispersions, which makes them ink‐jet printable. Different means of surface functionalization of the particles have been evaluated in order to optimize the dispersion stability at neutral pH. Furthermore, many of the particles have additional functionality, including superparamagnetic and fluorescent properties. Additionally, biologically active particles have been of special interest, where the particles contain active substances within the internal porosity, linked to the outer particle surface or both. Extensive electro‐kinetic characterization of non‐aqueous dispersions has also been carried out, again with special focus on dispersion stability. This is an important area of research, as non‐aqueous dispersions have been studied to a much lesser extent than aqueous dispersions, and relatively few literature reports can be found in this area. This is especially true for mixed‐solvent dispersions, which often are of key interest for ink‐formulation.

Thermodynamic Characterization of Lewis Functionalities on Dispersed Nano‐Materials

Main funding: Academy of Finland Participating FunMat unit: DPC Björn Granqvist, Gun Hedström and Jarl B. Rosenholm On the molecular level it is customary to subdivide the interaction forces into: nondirectional purely dispersive (hydrophobic) forces as well as directional Lewis acid‐base forces and electrostatic forces. The first mentioned two groups are in the older literature related with the denotation van der Waals forces. In modern literature the directional dipolar forces are referred to as Lifshitz‐van der Waals interactions.

The acid‐base concept is usually understood solely as a proton exchange (Brønsted activity), while the

Lewis acid‐base concept has attracted less attention despite its great importance. The Brønsted interaction is typical for aqueous solutions. The proton exchange produces charged species being involved in electrostatic interactions. The Lewis interaction, on the other hand, is characterized by the formation of an adduct between an acid (electron acceptor) and a base (electron donor). The Lewis interactions predominate in nonaqueous systems, such as oil dispersions, polymer matrices (composites) and gas reactions (e.g. catalysts).

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The aim of the project is to relate the thermodynamic parameters previously derived for the characterization of the Lewis type acid‐base site activities on functional solid surfaces with the properties determined with other instrumental methods. As a result of this characterization a semi‐empirical model will be developed which is based on the interaction parameters measured. The model enables a critical evaluation of the fundamental criteria upon which the published theories and the related experimental methods are founded.

Collaboration: Ian Wark Research Institute, Australia

Publications: B. Granqvist, G. Hedström and J.B. Rosenholm, “Acid‐Base Interaction of Probes at Silica Surface Microcalorimetry and Adsorption”, Journal of Colloid and Interface Science, 333, 49‐57 (2009) J.B. Rosenholm, “Solvent and Surfactant Induced Interactions in Drug Dispersions”, Colloids and Surfaces, A354, 197‐204 (2010).

Theoretical Modeling and Experimental Verification of Specific Ion‐Particle and Particle‐

Particle Interactions

Main funding: Academy of Finland Participating FunMat unit: DPC Per Dahlsten, Mats Granvik, Piotr Próchniak, Marek Kosmulski, Serge Durand‐Vidal and Jarl B. Rosenholm The interaction of ions with solid particles in aqueous electrolyte solutions leads to a space separation of electric charges at the particle/solution interfaces, known as the electrical double layer (EDL). The double layer is manifested in the electrokinetic phenomena. The structure and properties of the resulting EDL have long been a focus of intense scientific research. The main research has been devoted to dilute aqueous disperse systems using such experimental techniques as electrophoresis. However, a relatively new method to determine the particle electrokinetic properties based on the electro‐acoustic phenomena has recently been elaborated. Such measurements, due to their extended applicability, have gained an exceptional interest in recent years.

One of the major problems of such electroacoustic measurements is the interpretation of the signal at high ionic strength and particle concentration. To the best of our knowledge, the signal due to the added supporting electrolyte is not accounted for properly but is considered as a background noise which should be simply subtracted from the total signal. Alternatively the problem is accepted as a limitation of the technique itself. However, we have shown that the salt contribution cannot be neglected when the signal arising from the colloidal particles is weak (e.g. in the vicinity of the isoelectric point) and a simple subtraction cannot be performed because the various contributions are not additive. In order to improve the interpretation of the electroacoustic signal and to extract important information concerning the nature of the physicochemical processes at the particle surface (adsorption of monovalent or multivalent ions) a precise description of the salt contribution must be performed. We

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have therefore developed an analytical model which explicitly takes into account the relaxation effects and the hydrodynamic interactions between the various ionic species (individual ions and continuous liquid phase). The research has been supported by a prolonged collaboration with Prof. Marek Kosmulski, Dr. Serge Durand‐Vidal and Prof. P. Turq who are leading scientist in this field. As a proof of international appreciation of the research done Department of Physical Chemistry has been asked to host the International Electrokinetic Phenomena Conference in 2010. The outcome of the proposed joint multinational research would lay as an ideal example for the pre‐conference preparations. Collaboration: Technical University of Lublin and Pierre and Marie Curie University of Paris VI Publications: M. Kosmulski, P. Próchniak and J.B. Rosenholm, “The IEP of Carbonate‐Free Neodynium (III) Oxide”, Journal of Dispersion Science and Technology, 30,589‐591 (2009). M. Kosmulski, P. Prochniak and J.B. Rosenholm, “Electroacoustic Study of Titania at High Concentrations of 1‐2, 2‐1 and 2‐2 Electrolytes”, Colloids and Surfaces, A345, 106‐111 (2009). M. Kosmulski, P. Próchniak and J.B. Rosenholm, “Electrokinetic Potentials of Al2O3 in concentrated Solutions of metal Sulfates”,.Journal of Colloid and Interface Science, 338, 316‐318 (2009). Per Dahlsten, Piotr Próchniak, Marek Kosmulski, Jarl B Rosenholm,”Electrokinetic behavior of melamine‐ formaldehyde latex particles at moderate electrolyte concentration”, Journal of Colloid and Interface Science, 339, 409‐415 (2009). Marek Kosmulski, Piotr Próchniak, Jarl B. Rosenholm,”Electrokinetic study of adsorption of ionic surfactants on titania from organic solvents”, Colloids and Surfaces A: Physicochemical and Engineering Aspects, 348, 298‐300 (2009).

Marek Kosmulski, Piotr Prochniak, and Jarl B. Rosenholm,”Control of Zeta potential in semiconcentrated

dispersions of titania in polar organic solvents”, J. Phys. Chem., 113, 12806‐12810 (2009).

Marek Kosmulski, Piotr Próchniak, Jarl B. Rosenholm,”Solvents, in which ionic surfactants do not affect the zeta potential”, Journal of Colloid and Interface Science, 342, 110‐113 (2010). Marek Kosmulski, Piotr Próchniak, and Jarl B. Rosenholm,”Surface‐induced electrolytic dissociation of oxalic acid in polar organic solvents”, Langmuir, 26(3), 1904‐1909 (2010). M. Kosmulski, P. Próchniak and J.B. Rosenholm, “Interaction Between Surface Active Solutes and Surfaces of Metal Oxides in Polar Organic Solvents”, Submitted (2010.) P. Dahlsten, P. Prochniak, M. Kosmulski and J.B. Rosenholm, “Visco‐Coulombic Characterization of Aqueous and Alcoholic Titania Suspension”, Submitted (2010).

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Transport of Molecules and Ions in Porous Matrices Main funding: Graduate School of Materials Research Participating FunMat unit: DPC Espen Johannessen, Eddy W. Hansen and Jarl B. Rosenholm Most chemical analyses focus on equilibrium properties. However, the kinetic properties are of immense importance for the accurate modeling of chemical reactions and processes. Transport properties are most frequently related to capillarity and diffusion. In porous matrices, such as membranes and porous solids the characterization is restricted to indirect measurements. From the flow in and out of the porous matrix conclusions are drawn concerning the transport within the solid. Low‐field nuclear magnetic resonance provides a way to investigate the transport of molecules and ions in situ. The transport may further be used to interpret structural constraints for the diffusion and thereby define the internal structure. In this project models are developed for the diffusion of molecules and ions in porous matrices, such as wood and silica matrices. The tracheid structure is revealed for natural and petrified wood samples and for mesoporous silica matrices. Collaboration: University of Oslo, Norway Publication: E.H. Johannessen, E.W. Hansen and J.B. Rosenholm,”Diffusion Dependent Exchange Times Observed by PFG‐NMR”. Physical Chemistry Chemical Physics, submitted (2009)

Molecular Understanding of Printability (MolPrint, ended 2007)

Main funding: Finnish Funding Agency for Technology and Innovation (TEKES) Participating FunMat units: DPC, LPPC Mikael Järn, Carl‐Mikael Tåg, Joakim Järnström, Jouko Peltonen and Jarl B. Rosenholm

The investigation of liquid spreading on solid surfaces is usually restricted to equilibrium wetting of

nearly ideal, smooth polymers. Due to its complexity, less attention has been directed onto dynamic

wetting of rough, chemically heterogeneous polar surfaces. The aim in this study is to apply the most

common models developed for liquid spreading on pigment coated paper surfaces, for which the

equilibrium surface energy components have been determined previously. Two models have been used

to model the spreading of liquids on solid surfaces; the hydrodynamic and molecular kinetic model.

Hydrodynamic model describes the energy dissipation is a result of viscous drag within the spreading

droplet. The hydrodynamic model has showed the following asymptotic time‐dependence:

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R t1/10 Θ t‐3/10

Molecular‐kinetic model by Blake and Haynes describes the three phase contact line movement as a

stress modified molecular rate process involving adsorption of molecules of the advancing phase and

concurrent desorption of molecules of the receding phase, respectively. The molecular kinetic model

has showed the following asymptotic time‐dependence:

R t1/7 Θ t‐3/7

Publications: Review: C.‐M. Tåg, M. Järn and J.B. Rosenholm,“Radial Spreading of Ink and Model Liquids on Heterogeneous Polar Surfaces”, J. Adhesion Sci Tech, 24, 539‐565 (2010). M. Järn, C.‐M. Tåg, J. Järnström and J.B. Rosenholm,“Dynamic Spreading of Polar Liquids on Offset Papers” , J. Adhesion Sci Tech 24, 567‐581 (2010). J. Järnström, M. Järn, C.‐M. Tåg, J. Peltonen and J.B. Rosenholm,”Spreading of Probe Liquids on Ink‐Jet Papers”, J. Adhesion Sci Tech in press (2010).

Characterization and Control of Coating Layer Formation Main funding: KCL and Academy of Finland Participating FunMat unit: DPC Rasmus Eriksson, Annaleena Kokko, Heikki Pajari and Jarl B. Rosenholm

Industrially a most interesting question is what the result of interactions between particles in a coating

slurry is at process conditions. The free formation of the coating layer is of particular importance for,

e.g. curtain or spray coating processes. Sediment density and rheology has been utilized for the

characterisation of the state of dispersions. However, the parameters for the modelling of these time

dependent processes have generally been extracted from dilute model dispersion systems. In the

present project the macroscopic effect of the interactions was determined at solids contents

comparable to the industrially viable systems. This opens new perspectives to comprehensively

investigate homo‐ and hetero‐coagulation and flocculation processes in concentrated dispersions.

However, at high ionic strength the DLVO‐model fails to properly represent the experimental results.

Therefore, a number of correction terms have been added to the model. Such contributions are: steric

repulsion, Lewis acid‐base interaction and graininess (packing) of molecules (hydration) close to the

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surface. From an industrial point of view the extended DLVO‐theory, including steric interactions

provides the ideal platform to investigate novel alternative coating processes such as curtain and spray

coating (casting) processes. However, there is still a critical lack of proper understanding as concerns the

interaction under real process conditions. No generally accepted theory covers this range. Another area

of restricted research activity is the time‐dependent flux phenomena during dewatering and

sedimentation i.e. transport of liquid out from consolidating matrices. The latter transport phenomena

induces severe strain on the paper which may bending (warping of) the paper and induce cracks and

heterogeneities in the coating layer.

Collaboration: Helsinki University of Technology, University of Helsinki, VTT

Publications: R. Eriksson, H. Pajari and J.B. Rosenholm,”Shear Modulus of Colloidal Suspensions: Comparing Experiment with Theory”, Journal of Colloid and Interface Science, 332, 104‐112 (2009) R. Eriksson, A. Kokko, and J.B. Rosenholm, ”Rheological Characterization of the Influence of PVOH on Calcite Suspensions”, Langmuir, in press (2010)

Precipitation and Aggregation of Asphaltene in Organic Solvents Main funding: Neste and Finnish Funding Agency for Technology and Innovation (Tekes) Participating FunMat unit: DPC Bjarne Johansson, Rauno Friman, H. Hakanpää‐Laitinen and Jarl B. Rosenholm

The total combinatory Gibbs free energy was successfully used to model the solubility of two purified asphaltenes in neat and mixed solvents and the precipitation of the asphaltenes from mixed solvents. Intrinsic viscosity and particle size both sensitively reflected the state of the asphaltenes in homogeneous solution and were used for determining the solubility parameters of the asphaltenes. Phase separation was clearly reflected by a dramatic increase in particle size. The interaction parameter was subdivided into enthalpy and entropy contributions. All parameters indicate an extensive association or secondary phase transition when the phase border was followed by simultaneously varying the temperature and the solubility parameter of the solvent. However, derived in two ways, the enthalpy and entropy contributions lead to conflicting results. These were evaluated on thermodynamic grounds.

Collaboration: Neste Oil Corporation, Technology Centre

Publications: Review: J.B. Rosenholm, “Solubility and Interaction Parameters as References for Solution Properties. I. Exceptional Mixing and Excess Functions”, Advances in Colloid and Interface Sciences, 146, 31‐41 (2009).

B. Johansson, R. Friman, H. Hakanpää‐Laitinen and J.B. Rosenholm, “Solubility and Interaction Parameters as References for Solution Properties. II. Precipitation and Aggregation of Asphaltene in

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Organic Solvents”, Advances in Colloid and Interface Sciences, 147‐148, 132‐143 (2009). B. Johansson, R. Friman, P. Denifl and J.B. Rosenholm, “Influence of Polymers on the Emulsified Hydro‐ carbon Liquid and on the Surfactant Stabilized Toluene/Perfluoro‐octane Emulsions”, Journal of Dispersion Science and Technology, 30, 989‐996 (2009).

Review: Jarl B. Rosenholm:”Critical comparison of molecular mixing and interaction models for liquids, solutions and mixtures”, Advances in Colloid and Interface Science, 156, 14‐34 (2010).

Development of paper and for inkjet and electrophotography printing Main funding: Industry Participating FunMat units: DPC Carl‐Mikael Tåg, Petri Sirviö, Kaj Backfolk and Jarl B. Rosenholm, Papers available on the market for high speed inkjet and electrophotography printing can roughly be divided into treated grades and high quality specialty paper grades. The treated grades usually perform well in 1‐color printing, printing of barcodes etc., but not so well in 4‐color printing. The very expensive high quality specialty papers perform well in 4‐color printing, but not always so well in printing bar codes. Currently the high quality specialty paper grades are mainly produced on small paper machines, due to limited production possibilities.

The aim of the Inkjet and electrophotography paper project is to develop paper grades which perform well in high speed inkjet and electrophotography printing, but with less complex structure and at a lower cost than current specialty papers. To do this, evaluation of what makes a paper good or bad for high speed printing will be carried out. Additionally the aim is to decrease the paper waviness which causes problems in the post handling process of the printed product.

Publications: C.‐M. Tåg, M. Pykönen, J.B. Rosenholm, K. Backfolk:”Wettability of model fountain solutions: The influence on topo‐chemical and –physical properties of offset paper”, Journal of Colloid and Interface Science, 330, 428‐436 (2009). R. Maldzius, P. Sirviö, J. Sidaravicius, T. Lozovski, K. Backfolk and J.B. Rosenholm, “Temperature‐Dependence of Electrical and Dielectric Properties of Papers for ElectroPhotography”, Journal of Applied Physics, 107, 1 (2010) K. Backfolk, J. Sidaravicius, P. Sirviö, R. Maldzius, T. Lozovski, and J.B. Rosenholm, ”Effect of Base Paper Electrolyte Content and Grammage on Electrical and Dielectric Properties of Coated Papers”, Submitted (2010)

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Biomass derived novel functional foamy materials (Bio‐Foam) Main Funding: Finnish Funding Agency for Technology and Innovation (TEKES) Participating FunMat units: LPC N. He, R. Friman and J.B. Rosenholm

The objective of the project is to develop novel functional (solid) foamy materials from renewable natural polymers and biomass. This will be achieved by combining advanced polymer modification and analysis technologies to processing operations. The final aim is to replace man‐made, synthetic and expensive components currently used in porous composite structures and foams with renewable polymers and materials. The project belongs to the TEKES BioRefinery research framework.

A special emphasis is to apply a theoretical model developed at LPC for polymer interaction in liquids for the purpose to provide numerical specifications for and interaction predictions of the polymers and surfactants of particular interest. The Gibbs‐Marangoni conditions for the formation of the gas‐liquid (foam) interface will be established. Moreover, the aim is to establish the kinetics of foaming (drainage and coalescence) with conventional techniques. The physico‐chemical properties (Hamaker constant and repulsive potential) of the foam system will be related to the stability of the system.

Collaboration: Forcit Ltd., ÅAU, VTT

Publications: N. He, R. Friman and J.B. Rosenholm, “Solubility parameters of biopolymers”, Submitted (2010)

Internal Surfaces of mineral based functional materials (SIPI) Main Funding: Finnish Funding Agency for Technology and Innovation (TEKES) Participating FunMat units: LPC K. Gunnelius, J. Sarfraz, T. Lundin and J.B. Rosenholm The aim of the project is to develop knowledge of introduction of functional properties to porous inhomogeneous materials. When the interactions of nano‐scale internal surfaces, nano‐particles and nano‐scale surfaces can be tailored and the growth of the entire structure and its behavior adjusted. Then the reactions induced by the physico‐chemical properties can be controlled to produce desired functionalities. By modeling a base is created for the tailoring of materials at different severe process conditions, such as extremely high pH and ion concentration. The focus is placed on characterization of the interactions between inert and reactive nano‐sized particles at extremely high pH and ion concen‐trations (pI‐levels). In particular, the attractive interaction forces are modeled by determining the complex Hamaker constant and the repulsive forces are characterized by the effective zeta‐potential. In the next step the interactions are investigated for mixed dispersions, equaling model concrete in the presence of e.g. nano‐sized calcite and titania particles. The properties of concrete slurries and pastes are characterized for their particle size distribution, sedimentation and rheology. With suitable models the influence of polymeric additives and nano‐particles is established. The DLVO model is used as a self‐evident starting point, but it is modified to

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apply for the extreme process conditions. If possible the contribution from particle packing typical for concrete can be considered as a suitable model extension. Collaboration: Industry, VTT Publications: K.R. Gunnelius, Internal Surfaces of mineral based functional materials (SIPI): Rheology Project report, Laboratoy of Physical Chemistry, Åbo Akademi University, 2010 J. Sarfraz, External Surfaces of mineral based functional materials (SIPI): Sedimentation, MSc Thesis Laboratoy of Physical Chemistry, Åbo Akademi University (2009‐2010) K.R. Gunnelius, T.C. Lundin, J.B. Rosenholm:”A comparison of the rheological properties oa aqueous

suspensions of industrial anatase titania”, manuscript.

K.R. Gunnelius, T.C. Lundin, J.B. Rosenholm:”Rheology os suspensions of an industrial calcium carbonate

pigment at different shear rates and electrolyte concentrations”, manuscript.

Influence of electrokinetic charge on rheology and settling of non‐inert/reactive

dispersions/suspension

Main Funding: Saint Gobain / Maxit Ltd. and Nordkalk Ltd. Participating FunMat units: LPC T. Lundin, K. Gunnelius and J.B. Rosenholm The first part of the project aimed at rheometric characterisation of reactive suspensions dispersed to fluidity for enhanced performance, both spatial and temporal. Initially standard rheometers were compared for basic concordance and the available geometries investigated for their respective suitability. Secondly the collected data were investigated and interpreted to apply and develop the dispersion‐specific rheometer procedures. The various dispersions could be described at their different processing stages (e.g. mixing, pumping and pipe flow) by their respective rheological performance. Rheometry offers thus tools to develop numeric descriptors of relevance in both product development, processing and application situations. A comparison of results obtained with different rheometers will always be influenced by deviations in their measuring geometries. The comparison reliability of results increased with minimised geometric deviations indicating good rheometer concordance. In the second part of the project calcium carbonate dispersions were characterised by electrokinetic methods, conventional gravitational settling and thermogravimetric methods. The colloidal particles were initially unstable displaying rapid flocculation, agglomeration and settling tendencies due to strong interparticle attractive forces, following from high surface potentials. The time stability was assessed by an approach where different synthetic, organic polymers were added, sorbed and analysed quantitatively. At native pH‐values (6‐7) the particles settled and coalesced rapidly into loosely packed sediments. At the point of zero charge (pzc) the particle repulsive forces were minimised that provided a strong agglomeration with a compressive‐type settling.

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Collaboration: Saint Gobain / Maxit Ltd. and Nordkalk Ltd., VTT, HUT

Publications: T. Lundin, “Rheological characterisation of curing suspensions”, Project report, Laboratory of Physical Chemistry, Åbo Akademi University, 2009. (Confidential) T. Lundin, “Characterization of NC‐suspensions, Project report, Laboratory of Physical Chemistry, Åbo Akademi University, 2010.

Nanopatterned, Functional Surfaces by Design (NanoFused) Funding: Academy of Finland Participating FunMat units: DPC, DPh Qian Xu, Jan‐Henrik Smått, Simon Sandén, Gytis Sliaužys, Ronald Österbacka, Mika Lindén Nanostructured porous inorganic and hybrid inorganic‐organic films are interesting materials for a wide range of applications. Within the framework of the NanoFused project novel thin films for selected applications, with special emphasis on optoelectronics, sensing, and cell attachment, where the film structure and function is a result of a molecular optimization and design process. Thus, the project covers all aspects from synthesis, characterization, functionalization, to application. Nanostructured films of semiconducting metal oxides, like TiO2 and ZnO, and their further functionalization by introduction of functional organic molecules serve as the basis for the material development.

Non‐FunMat project partners: Biomaterials Center, Turku, Department of Chemistry, University of Joensuu

Co‐operation: Pierre and Marie Curie University, Paris, France, Vilnius University, Vilnius, Lithuania

Publications: M. Kuemmel, J.‐H. Smått, C. Boissière, L. Nicole, C. Sanchez, M. Lindén, D. Grosso, “Hierarchical inorganic nanopatterning (INP) through direct easy block‐copolymer templating”, J. Mater. Chem. 19, 3638‐3642 (2009) S. Lepoutre, J.‐H. Smått, C. Laberty, H. Amenitsch, D. Grosso, M. Lindén, “Detailed study of the pore‐filling processes during nanocasting of mesoporous films using SnO2/SiO2 as a model system”, Microporous Mesoporous Mater., 123, 185‐192 (2009) M. Järn, Q, Xu, M. Lindén, “Wetting studies of hydrophilic‐hydrophobic TiO2/SiO2 nanopatterns prepared by photocatalytic decomposition”, Langmuir, in press (2010)

Biologically guided nanoparticles – Targeting, safety and imaging technology (Biotarget)

Funding: Academy of Finland

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Participating FunMat units: DPC Lotta Bergman, Mika Lindén The development of nanotechnology is expected to lead to fast improvements in medical imaging and drug delivery. At the same time there are increasing concerns related to the safety issue. The aim of the project is to develop silica‐based, biologically targeted nanoparticles, which could be used in drug delivery or in the targeting of antigens to immunoresponsive cells (vaccination). Furthermore, novel imaging methods will be developed to analyze the fate of the particles in living cells and tissues. Of special interest is the evaluation of the biological safety of the particles and one of the aims of the project is to set criteria for nanoparticle toxicity in the immune system and at a single cell level.

Non‐FunMat project partners: Department of Biochemistry, University of Turku, MediCity research

laboratory, University of Turku, Computer Science, Åbo Akademi University

3g‐Nanotechnology based targeted drug delivery using the inner ear as a model target organ (NanoEar)

Funding: EU

Participating FunMat units: DPC Alain Duchanoy, Jessica Rosenholm, Lotta Bergman, Eva von Haartman, Mika Lindén The purpose of this project is to demonstrate the feasibility of targeted drug delivery using nanotechniques. Third generation multifunctional nanopaparticles (3G‐MFNP), which are biodegradable and traceable in‐vivo, are being developed for selective drug delivery. In parallel, other nanoparticles; lipid core nanocapsules, plasmids, dendrimers and hyperbranched polymers are also being developed. The proposed studies aim to assess the organ specific drug delivery potential of nanoparticles in the inner ear as an experimental target organ. The unique features of these nanoparticles include: biocompatibility, biodegradability, non‐toxicity, and EU‐approved material composition. The surface characteristics of these particles can be designed for selective targeting of specific tissues and cell types. In this project we will target sensory epithelium (inner ear hair cells), spiral ganlion cells and vascular tissue (stria vascularis) of the inner ear. The structure of the 3G‐MFNPs allows incorporation of a drug, gene or gene product as well as tracers, permitting in‐vivo verification and quantification of their release and distribution to target sites using Magnetic Resonance Imaging (MRI)‐based technology. The nano‐layers are developed for special body sites were bioactive electrodes are used for drug delivery.

Non‐FunMat project partners: 25 partners from all over Europe

Publications: J.M. Rosenholm, E. Peuhu, L. Tabe Bate‐Eya, J.E. Eriksson, C. Sahlgren, M. Lindén, “Cancer‐Cell‐Specific Induction of Apoptosis Using Mesoporous Silica Nanoparticles as Drug‐Delivery Vectors”, Small, in press J.M. Rosenholm, C. Sahlgren, M. Lindén, “Towards intelligent, targeted drug delivery systems using mesoporous silica nanoparticles – Opportunities & Challenges”, Nanoscale, in press

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Specific Targeting of Cancer Cells by Design ‐ Nanoparticles as Drug Delivery Systems

Funding: Tor, Joe and Pentti Borg foundation

Participating FunMat units: DPC Jessica Rosenholm, Mika Lindén One of the big challenges of medicine today is to deliver drugs specifically to the defected cells. This is of

special importance in cancer treatment as many of the pharmacological agents developed are harmful

for non‐cancerous cells. The aim of the project is to develop and evaluate the use of nanoparticles as

delivery systems to specifically target cancer cells. Due to the large surface area and the controllable

surface functionality of the silica nanoparticles, they can be loaded with large amounts of drugs and

coupled to molecules of choice for targeting purposes. Preliminary data show that particles linked to

tracking molecules are specifically recognized and taken up by cancer cells as compared to particles

lacking these tracking devices. A long term goal will be to evaluate the power of these particles to

selectively target cancer cells in vivo in a mouse tumor model.

Non‐FunMat project partners: Department of Biology, Åbo Akademi University

Publications: J.M. Rosenholm, A. Meinander, E. Peuhu, R. Niemi, J.E. Eriksson, C. Sahlgren, M. Lindén, “Targeting of Porous Hybrid Silica Nanoparticles to Cancer Cells”, ACS Nano, 3 197‐206 (2009) J.M. Rosenholm, E. Peuhu, J.E. Eriksson, C. Sahlgren, M. Lindén, “Targeted Intracellular Delivery of Hydrophobic Agents Using Mesoporous Silica Nanoparticles as Carrier Systems”, Nano Letters, 9 3308‐3311 (2009) Versatile Metal Oxide Materials for Usage as Biomolecular Separation Media and Sensors

Funding: Academy of Finland

Participating FunMat units: DPC Motolani Sakeye, Mika Lindén, Jan‐Henrik Smått The overall aims of the applied project are twofold: a) to synthesize, characterize, and functionalize novel non‐siliceous porous materials with a controlled morphology, and b) to study the performance of these materials in selected nanotechnological applications in order to establish rational structure‐activity and composition‐activity relationships. The chosen applications are namely phosphopeptide enrichment, phospholipid coatings for use in analyte‐membrane partitioning studies, and gas sensors. Especially within the fields of biomolecule separation and gas sensing, it is important to differentiate between the influences of the surface chemistry on the one hand and the pore structure and macromorphology on the other. When successful, the obtained results can serve as a platform for further rational material optimization cycles, rather than having to use a time consuming trial and error method.

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Collaboration: Department of Biology, Åbo Akademi University, University of Vienna, Vienna, Austria,

Universität Paderborn, Paderborn, Germany, University of Alabama, USA

Publications: S.Y. Imanishi, P. Kouvonen, J.‐H. Smått, M. Heikkilä, E. Peuhu, A. Mikhailov, M. Ritala, M. Lindén, G.L. Corthals, J.E. Eriksson,” Phosphopeptide enrichment with stable spatial co‐ordination on a titanium oxide coated glass slide”, Rapid Commun. Masspectrometry, 23, 3661‐3667 (2009) A. Leitner, M. Sturm, J.‐H. Smått, M. Järn, M. Lindén, K. Mechtler, W. Lindner, “Optimizing the Performance of Tin Dioxide Microspheres for Phosphopeptide Enrichment”, Anal. Chim. Acta, 638 , 51‐57 (2009)

A. Leitner, M. Sturm, O. Hudecz, M. Mazanek, J.‐H. Smått, M. Lindén, W. Lindner, K. Mechtler, “Probing the phosphoproteome of HeLa cells using nanocast metal oxide microspheres for phosphopeptide enrichment”, Anal. Chem., in press

F. Maddox, C. Cook, L. McKenzie, B. O'Neil, E.A. Junkin, C. Redden, S. Basu, M.G. Bakker, J.‐H. Smått, Mika Lindén, “Development of Ultrahigh Surface Area Porous Electrodes using Simultaneous and Sequential Meso‐ and Micro‐structuring Methods”, Mater. Res. Soc. Symp. Proc. 1127, T04‐08 (2009)

F. Maddox Sayler, M.G. Bakker, J.‐H. Smått, M. Lindén, “Correlation between Electrical Conductivity, Relative Humidity and Pore Connectivity in Mesoporous Silica Monoliths”, J. Phyc. Chem. C, in press

Synthesis and characterization of magnetic, gold‐functionalized nanoparticles for use in

biological applications

Funding: Finnish Funding Agency for Technology and Innovation (TEKES)

Participating FunMat units: DPC Lotta Bergman, Jessica Rosenholm, Mika Lindén

Self‐assembly based synthesis of nanoparticles is a highly versatile route towards state‐of‐the‐art nanoengineering of functional materials. One of the most promising areas of nanoparticle research, both in terms of academic interest and possibilities for high‐value applications, is nanoparticle‐based systems same particles. The aim of the project is to synthesize magnetic particles surrounded by a silica core onto which gold nanoparticles are immobilized, but with a labile bond, so that the gold particles can be released by external stimuli. The final aim of the project is to use the magnetic silica particles as carriers for genes which are attached to the gold nanoparticles, and the gold particles together with the genes are then released locally in order to enhance the expression of the genes.

Collaboration: Shanghai Jiao Ting University, Shanghai, China

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Printable gas sensors (Sub‐project of the larger Flex‐Sense consortium project) Funding: Finnish Funding Agency for Technology and Innovation (TEKES)

Participating FunMat units: DPC, DPh, LPT Jawad Sarfraz, Daniel Tobjörk, Ronald Österbacka, Mika Lindén The aim of this project is to develop printable gas sensors based on polyaniline using paper as the substrate. The target gases are H2S and NH3, and we are focusing on irreversible sensors which can be used as low‐cost sensors for example within the food packaging industry.

II‐RC

Funding: Stora Enso

Participating FunMat unit: DPC Janne Puputti, Mika Lindén Industrial proprietary project.

Development and application of magnetic, silica‐magnetite nanoparticles for use in high‐throughput

biological applications

Main funding: Finnish Funding Agency for Technology and Innovation (TEKES)

Participating FunMat unit: DPC Lotta Bergman, Jessica Rosenholm, Mika Lindén The project focuses on the development of composite particles of superparamagnetic iron oxide and mesoporous silica to be used for selective separation of biomolecules from complex biological fluids by a combination of molecular recognition and magnetic fields.

Collaboration: Shanghai Jiao Ting University, Shanghai, China and three companies

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3.2.2 Synthesis of organic particulate meso‐structures and core/shell capsules Professor Carl‐Eric Wilén At present some of the most exciting work on advanced functional material development is being made in macromolecular sciences and engineering due to plastics versatility with respect to chemical and mechanical properties. It has now become possible to introduce specific properties to polymeric materials in terms of morphology, topology, interconnected porosity and functionality through molecular engineering and/or processing. As a consequence of this, functional polymers have been developed for a wide range of applications including optoelectronics (conducting polymers, magnetic polymers and polymers for nonlinear optics), photographic materials, sensors, paper coatings, specialty membranes, gels, biomaterials, organic catalysis (supported catalysts), paints, additives, etc. Our objective is to introduce specific functionality to various polymeric materials by controlled synthesis, post modification, blending or by addition of specialty additives. In particularly, the correlation between material properties and chemical composition is of great interest. The aim is to prepare novel polymeric materials that can successfully be used in various electronic devices by paper industry, printing houses and industry specialized in diagnostics. The laboratory of polymer technology at Åbo Akademi University within the FUNMAT consortia will focus on the following topics: a) radiation induced grafting b) polymer synthesis (e.g. controlled free radical polymerization techniques) of biopolymers and dispersing agents, c) preparation of functional organic‐mineral hybrid materials and d) design and use of novel plastic additives and modifiers e) ion conductive membranes that can be utilized in OFETs and various organic devices.

Development of two component oxirane ester paint hardeners

Main funding: Industry

Participating FunMat unit: LPT Minna Kaskinen, Ari Rosling and Carl‐Eric Wilén

The aim of this thesis is to gain knowledge of the characteristics and behavior of the two component oxirane ester paint hardener Duasolid 50. The current synthesis is studied and the product is developed. The main goal is to decrease the amount of free chlorendic acid in the product as well as to obtain a clear and colorless product with desired viscosity and hardening properties.

The theoretical part of this thesis deals mainly with paints and coatings in general, their composition and properties and the basic reactions behind the synthesis of Duasolid hardener. The raw materials used in the experimental part of this work are presented and the polymer definition according to REACH is reviewed. The last chapter goes shortly into the safety issues related to the laboratory work.

In the experimental part of this study three series of experimental hardeners were synthesized. Series 1 was a screening series of 14 different kinds of hardeners. Based on the viscosity and hardening properties of these synthesis products a 23 factorial design was planned in order to model the effect of the raw material composition on the viscosity of the hardener. Series 2 consists of the 11 syntheses of

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the factorial design plan. After the factorial design series additionally 4 complementary syntheses were carried out (Series 3).

The physical and chemical properties of the experimental hardeners were determined and the hardeners’ performance in a paint system was studied.

In comparison with current Duasolid hardeners, the new experimental products showed improved appearance. Almost all of the hardeners were clear and colorless. The amount of residual chlorendic acid in the products was also decreased significantly in certain syntheses.

Regression models obtained from the factorial design can be utilized in designing experiments in the future. According to their appearance and drying properties, some of the hardeners might as such be ready for taking into production.

Cooperation: Tikkurila Publication: Minna Kaskinen, Master thesis 2009

Modified Maleimide Copolymers

Main funding: Center of Excellence in Functional Materials

Participating FunMat unit: LPC Mia Koskinen and Carl‐Eric Wilén The reaction between maleic anhydride and amine produces maleimide and can easily be tailor‐made by using different primary amines to give functionality with designed properties. We have prepared aqueous nanodispersions of modified poly(styrene‐co‐maleimide) (SMI) and poly(octadecene‐alt‐maleimide) (OMI) from respective maleic anhydrides which both are commercially available polymers with high thermal stabilities. [1‐3] Modifications (see Scheme 1) were done by 4‐amino‐2,2,6,6,‐tetramethylpiperidine (TAD), L(+)‐aspartic acid (ASP) and fluorinated compounds. Finally we applied the modified maleimide nanoparticles on paper coating as speciality pigments.

Scheme 1: Modified maleimide copolymers where R1 is phenyl (SMI) or n‐hexadecyl (OMI) and R2 is TAD,

ASP, TFEA or HFEA.

O O

H2CHC

R1

R2

N

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We have successfully modified poly(styrene‐co‐maleimide) and poly(octadecene‐alt‐maleimide) copolymers by 4‐amino‐2,2,6,6,‐tetramethylpiperidine, L(+)‐aspartic acid and fluorinated compounds. These modified copolymers were applied in paper coating as auxiliary pigments. Full effect of the modifiers was not yet achieved and thus their concentration requires further optimization. The possibilities for modification of this versatile material are numerous.

Collaboration: Finnish Funding Agency for Technology and Innovation (TEKES), Center of Excellence for Functional Materials (FunMat), Ciba Speciality Chemicals and NV Topchim SA for scientific advice and funding of the project.

Publications: Ahokas, Mia; Wilen, Carl‐Eric “Synthesis of poly(styrene‐co‐maleimide) and poly(octadecene‐co‐maleimide) nanoparticles and their utilization in paper coating”, Progress in Organic Coatings, 66(4), 377‐381 (2009) Mia Ahokas, Carl‐Eric Wilén, "Modified and Functional Maleimide copolymers", submitted to Polymer Bulletin Mia Ahokas, Carl‐Eric Wilén, "Poly(styrene‐co‐maleimide)/Kaolin/Alumina trihydrate Hybrid Coating Pigments for Paper and Board ", submitted to Progress in Organic Coatings.

Production of bioactive paper and fibre products (BioAct)

Main funding: Finnish Funding Agengy for Technology and Innovation (Tekes)

Participating FunMat units: LPT, LPCC Pernilla Sund and Carl‐Eric Wilén

The contribution by the Laboratory of Polymer Technology to the BioAct project consists of two parts: a) synthesis of a macrocycle library, and b) development of a printable monomer mixture, that gives a hydrogel after UV‐initiatied polymerization.

The macrocycle library, which is synthesized on polystyrene beads, is intended for macrocycle‐functionalization of (bio)polymers, to be used primarily for sensors, but also for other applications. The task of the macrocycles is to achieve strong and specific interaction with the analytes.

Although combinatorial libraries have been used extensively for drug discovery, few have been developed for other industrial purposes. For industrial applications, the priority is cheap monomers and synthesis, and good chemical stability. Macrocycles are preferred to open chains because the conformational preorganisation in macrocycles gives stronger and more specific association to the target. Macrocycles also have the ablility to strike a compromise between structural preorganisation and flexibility to achieve optimal binding.

The macrocycle library is synthesized using solid‐phase synthesis (SPS) on polystyrene beads, as a one bead ‐ one compound library using the mix‐and‐split method. The macrocycle is attached to the polystyrene bead using a linker that will be cleavable for the library, but permanent for the final application. The linker attachment point on the macrocycle ('head monomer') also functions as the site for ring‐closure. The rest of the macrocycle consists of an amide oligomer. The chemistry used for ring‐

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closure is 1,3‐dipolar cycloaddition between a propargyl group and an azide group, the latter attached to the end monomer.

For the first attempt at making a macrocycle, a phenacyl linker, and a rather complex head monomer syntheized in solution was used. The completed 14 atom macrocycle was cleaved off with hydrazine, chromatographically purified and characterized by nuclear magnetic resonance (NMR) and mass spectrometry (ESI‐MS).

Because of different shortcomings, a new linker and a smaller and more easily synthesized head monomer was also made, and the testing of these is ongoing.

Hydrogels. A printable hydrogel must remain liquid in the printing process, and then be cured into a non‐flowing hydrogel afterwards. To achieve this, UV‐polymerizable inks based on acrylic acid monomers have been tested. The swelling of the corresponding hydrogel depends on pH, so that in acidic solution, where the carboxyl groups are un‐ionized, the swelling is low, while in basic solutions with ionized carboxyl groups, the hydrogel will swell.

The hydrogels were composed of acrylic acid, a crosslinker, a sensitizer, and a solvent. Several solvents were tested for printability and gel properties.

Collaboration: VTT and industry. Publication: ChenThan, Master Thesis to be finalized by June 2010.

In vitro study on cell adhesion and signaling on degradable bioactive composite surfaces


Participating FunMat unit: LPT Eeva Orava and Ari Rosling

The project has recently started and the aim of the research is to study cell adhesion, maturation and cell released biochemical molecules in contact with various polymeric implant surfaces. A key role in the success or failure of an implanted material or device is the level of influence that the material can exert over cell differentiation. Modulated surface properties are expected to affect the adhesion, differentiation and proliferation of cell. Suitable chemical triggers or surface topography can determine the cell behaviour at the implant surface. The project will provide valuable information on the control of cell contact on different surfaces, which can be utilized in optimization of tissue engineering scaffolds.

Collaboration: The work was performed in collaboration with Dr. Molly Stevens, Reader in Regenerative Medicine and Nanotechnology at Imperial Collage London, UK, where the practical work is performed.

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Reactive in situ curing polymers for regenerative medicine


Participating FunMat unit: LPT Peter Uppstu, Ari Rosling

The purpose of this study is to develop a viscous in‐situ hardening, though biodegradable composite material for cartilage and bone defects. Polymer synthesis will be developed and subsequent curing reactions are studied by DSC. The rheological properties of the initial dough and its setting behavior will further be studied.

Collaboration: Vivoxid LtD, Finland

Publication: Patent negotiations ongoing.

Hydrophilization of PLLA by blending with hydroxy‐modified poly(lactide‐co‐caprolactone).

Porous scaffold preparation and their hydrolytical degradation in SBF.


Participating FunMat unit: LPT Peter Uppstu, Eeva Orava, Ari Rosling

Porous biodegradable matrices based on synthetic aliphatic polyesters are used in several medical applications. They are usually synthesized by ring opening polymerisation from corresponding cyclic diesters. Copolymers with different compositions and molecular weights can further be synthesized to achieve specific physical and chemical characteristics. Despite an ample amount of studies these materials often remains too hydrophobic being difficult to wet.

Our main objective is to prepare new tailored synthetic biodegradable polyester‐based homo‐ and copolymers especially with improved water adsorption properties. The ultimate scaffold structures are primarily intended for utilization either as temporary scaffolds or as carriers for bioactive molecules and bioactive inorganic materials.

Collaboration: Vivoxid LtD, Finland

Publication: Patent issues are under negotiation

Rheology of Plastic Bonded Explosives


Participating FunMat unit: LPT Jonas Lithén, Ari Rosling

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Plastic bonded explosives, (PBX), are high explosive compositions consisting of high explosive compounds, polymer‐based binders and additives. Their advantages are many e.g. more easily shaped when casting or compressed into complex shapes, as traditional explosives which usually requires hazardous melting. Ideally PBXs are low viscosity compositions enabling them to be poured into complex moulds with thin flow channels, like mines or grenades or booster caps. Low viscosity makes manufacturing in large scale less complex and enables more freedom in design and the composition does not need to be heated for viscous casting purposes. A big problem is to optimize explosive and flowing properties of PBX compositions. Increased solid explosive content increases explosive power but also increases sensitivity and viscosity.

The research results are confidential.

Collaboration: Forcit Ab, Finland

Publications: Jonas Lithen, "Rheology of Plastic Bonded Explosives" Master Thesis 2009

Novel Biopolymer Coatings


Participating FunMat unit: LPT Mohammad Kajeheian (Master thesis), Virpi Ääritalo, Nasir Zeeshan (Master thesis), Anton Holappa,

Carl‐Eric Wilén and Ari Rosling

The purpose of food packaging is to preserve the quality and safety of the food as well as protect the product from physical and chemical, or biological damage. For over 50 years polyethylene based materials have been the most frequently used packaging material by the food industry. Environmental concerns regarding use of non‐renewable oil resources and constantly growing waste streams have brought to attention alternative packaging materials from renewable sources that are capable of degrading in soil or during composting.

Paperboard with a polymer coating may serve as packaging material for many products, not only food. The end application though strongly dictates the necessary material properties.

In this project we develop packaging products based on biodegradable polymers from annually renewable sources. The polymer properties are tailored to meet requirements set forth by processing, conversion and end use applications.

The research results are subjected to confidentiality agreement between StoraEnso and Åbo Akademi

University.

Collaboration: Stora Enso, Finland

Publication: Zeeshan Nasir "Correlating Polymer Thermal Properties with Heat Sealing Properties" Master thesis 2010.

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Novel Biomaterials for Cartilage Tissue Engineering

Main funding: Finnish Funding Agency for Technology and Innovation (Tekes)

Participating FunMat unit: LPT Peter Uppstu, Virpi Ääritalo, Ari Rosling

The aim of the project is to develop novel biomaterials for cartilage repair. The combination of chondrocytes in novel biodegradable scaffolds implanted to the cartilage lesion site may facilitate the repair of joint cartilage and the underlying bone faster and better than the current surgical methods available. The major problem in applying these tissue technologies to clinical use has been the lack of proper implant materials. Thus focusing in the biomaterial development is essential. Small cartilage damages may be treated with gel‐like implants. Large cartilage damages, where the bone is intact, need mechanically more rigid implants. In injuries where also the underlying bone has been damaged, an implant with both bone and cartilage repairing features is needed. Our research group has the objective of producing and testing novel biomaterials for osteochondral lesion repair studies. The aim is to produce a porous scaffold, which will then be combined with human recombinant collagen II gel and chondrocytes.

Collaboration: Tampere Technical University, Helsinki University, Fudan Universtiy Hospital, Zhongshan,

Shanghai, China and several industrial partners.

GREEN COMPOSITE ‐ Environmental‐friendly and strong woodfibre reinforced

starch/hemicellulose composite.


Participating FunMat unit: LPT Duanmu Jie, Ari Rosling

The aim of the present work is to develop environmental‐friendly structural composites based on woodfibres and starch/hemicellulose from Nordic agriculture and forestry biomass streams to substitute conventional synthetic composite materials from fossil hydrocarbons. Thus we forward an added value to the already existing production of both starch/hemicelluloses and cellulose.

Our earlier work has dealt with allylglycidylether‐modified starch with very low to high degree of substitution which has been transformed into wood fiber reinforced composites. The high degree substitution‐matrix (HDS) was suitable for composite preparation even with extremely high wood fibre contents. The less manipulated LDS matrix also exhibits good matrix‐fibre contact, though it produced composites with heterogeneous surface properties. The heterogeneity is also reflected in the LDS composites mechanical properties. Though, with a partial enzymatic degradation the LDS matrix became more processable and the hygromechanical properties reached those of HDS. Microfribrillated cellulose where also tested for its reinforcing properties at 10 w% fiber loadings, showing similar tensile strength properties as those made of LDS and HDS with 40‐60 w% soft wood fiber loadings. However, the water

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adsorption was dramatically reduced. The upcoming studies will concentrate on utilization of forestry biomasses (e.g. hemicelluloses) for composite preparation. Focus is placed on developing strategies to bring forward processes implementable in to industrial scale processes.

Collaboration: STFI‐Packforsk AB, Sweden, KTH University, Sweden, Wallenberg Wood Science Center

Effects of Titanium dioxide /PCC masterbatch compositions on polyethylene films with regard

to brightness and opacity.


Participating FunMat unit: LPT Nasir Zeeshan, Ari Rosling

Precipitated calcium carbonate (PCC) is a useful additive for a wide range of plastic and elastomeric applications. Its crystalline shape and availability in variable particle size together with given hydrophobicity, provides enhancement of both polymer processing and subsequent physical properties.

In this study filled polymer films were made by masterbatch extrusion. The masterbatches were prepared of commercial TiO2 which was partially substituted with experimental PCC filler. The films were tested especially for brightness, opacity and tensile properties. Filler distribution was studied with SEM.

Collaboration: FP‐Pigments Oy, Finland

Design of novel non‐halogenated flame retardants – combustion and polymer scientists join

forces

Main funding: Academy of Finland and Ciba Specialty Chemicals

Participating FunMat unit: LPT Melanie Aubert, Weronica Pawelec, Teija Tirri, Ronan Nicolas and Carl‐Eric Wilén

Flame retardants have been used for centuries to reduce the flammability of materials; in the modern society inexpensive and effective brominated flame retardants are used in public transport (aircrafts, cars, trains, etc.), buildings/constructions and increasingly in housings for electrical/electronics equipment. However, a serious subset of these halogenated flame retardants are that new evidence shows that they persist in our environment, bioaccumulate in the food chain and in our bodies, and may cause adverse effects in our children. This means that brominated flame retardants should be replaced with safer non‐halogenated alternatives.

Recently, we have been able for the first time to identify azoalkanes as a novel and effective class of flame retardants for polyolefins. This observation has opened up new opportunities to design a number of non‐halogenated flame retardants based on diazene and related structures that are of both academic and industrial interest. Currently, we are exploring in detail the structure‐property relationships of various diazene derivatives and investigating their synergistic effects with conventional flame retardant systems.

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Our aim is to further make considerable advances in flame retardancy of polymeric materials by combining for the first time the skills and knowledge of combustion and polymer scientists. We believe that by better understanding the broader aspects of combustion and interaction of flame retardants therewith would enable us to design environmentally friendly flame retardant systems with enhanced performances. This effort will be based on interdisciplinary work and sound scientific principles to construct a novel tool‐box that will be helpful in rendering any polymeric material fire retardant. Collaboration: Finnish Academy of Science, Ciba Specialty Chemicals, Switzerland, and Process Chemistry Centre, Åbo Akademi University Publications: Melanie Aubert, Ronan C. Nicolas, Weronika Pawelec, Carl‐Eric Wilén, Michael Roth, Rudolf Pfaendner “Azoalkanes ‐ novel flame retardants and their structure property relationship” Polymers for Advanced Technologies“, in press, DOI: 10.1002/pat.1642 (2010) Mélanie Aubert, Carl‐Eric Wilén, Rudolf Pfaendner, Simon Kniesel, Holger Hoppe and Michael Roth, “Bis(1‐propyloxy‐2,2,6,6‐tetramethylpiperidin‐4‐yl)‐diazene – an innovative multifunctional radical generator providing flame retardancy to polypropylene even after extended artificial weathering ” Polymer Degradation and Stabilization, in press Doi:10.1016/j.polymdegradstab.2010.02.035 (2010)

Non‐halogenated fire retardants for two component polyurethane adhesive Main funding: Industry Participating FunMat unit: LPT Bartosz Ziółkowski, Norouzian Amiri, Melanie Aubert, Teija Tirri and Carl‐Eric Wilén

This work has been focusing on finding suitable non‐halogenated flame retardants for polyurethane adhesives. Firstly, a broad literature study has been conducted in order to find suitable candidates and secondly novel flame retardants have been synthesized and admixed with the polyurethane precursors, i.e. polyol. The flame retardant testing of polyurethane plaques has been mainly conducted by cone calorimeter, whereby the rate of heat release, total heat release, amount of residue and average rate of heat emission values have been recorded and analyzed. Collaboration: Kiilto Oy and Process Chemistry Centre, Åbo Akademi University Publications: Bartosz Ziólkowski, "Non‐halogenated fire retardants for two component polyurethane adhesive" Master Thesis 2009. Norouzian Amiri, Carl‐Eric Wilén, "Polyurethane nanocomposites and their preparation and flame retardant properties" submitted to Polymers for Advanced Technologies.

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Porous versus novel compact Ziegler‐Natta catalyst particles and their fragmentation during early

stages of bulk propylene polymerization


Participating FunMat units: LPT, LPC Torvald Vestberg, Peter Denifl, and Carl‐Eric Wilén

It is well known that the nature of the catalyst support plays an important role in polymerization of olefins with Ziegler‐Natta and single site catalysts. According to most of the present literature, the physical strength and porosity of the support and final catalyst has a strong influence on both activity and polymer particle morphology. It was early suggested that it is the stress of the growing polymer that causes a progressive fragmentation of the catalyst particle. Galli et al stressed that a catalyst, used in propylene polymerization, should have high surface area and porosity as well as suitable mechanical strength in order to give high activity and good polymer powder morphology in an industrial process. It is also well recognized that fragmentation of the catalyst during the early stage of polymerization is decisive for the final polymer powder morphology.

In several studies where SiO2 has been used as support it has been observed that the initial fragmentation of this support normally proceeds layer by layer. This has been shown with ZN catalyst for polyethylene and with single site catalysts for polypropylene and polyethylene. The strength and dimensions of the interconnecting network, in addition to the total pore volume, are important factors for controlling fragmentation and nascent polymerization with silica based catalysts.

More recently, there have been reports in the literature of a catalyst that has neither measurable surface area nor porosity by BET analysis, but still has high activity and good powder morphology. The catalyst gives under mild conditions roughly the same activity in the early stage of polymerization as a porous catalyst with the same chemistry. The catalyst gives under conditions used in industrial processes good powder morphology. The behavior of this catalyst seems to conflict with what we know is a prerequisite of a good catalyst: high surface area and porosity. The target of this study is to investigate fragmentation of the catalyst, when polymerization is conducted under typical industrial process conditions, and to try to understand why the catalyst works so well despite its compactness.

Collaboration: Borealis Polymers

Publications: Valtola, Lauri; Hietala, Sami; Tenhu, Heikki; Denifl, Peter; Wilen, Carl‐Eric, “Association behavior and properties of copolymers of perfluorooctyl ethyl methacrylate and eicosanyl methacrylate”. Polymers for Advanced Technologies, 20(3), 225‐234 (2009). Torvald Vestberg, Peter Denifl, Matt Parkinson, Carl‐Eric Wilén, “Effects of External Donors and Hydrogen Concentration on Oligomer Formation and Chain End Distribution in Propylene Polymerization with Ziegler‐Natta Catalysts”, Journal of Polymer Science Part A: Polymer Chemistry, in press; published online: Dec 7 2009 (2010).

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Relaxation of PEX pipes


Participating FunMat unit: LPT Sara Penttinen and Carl‐Eric Wilén

Previously, it has been discovered that PEX materials possess useful memory based on the interplay between deformation and subsequent strong relaxation. After the material has been abruptly expanded the material still has a strong tendency to return to its original shape. Industry is exploiting this memory characteristic as a part of their extended PEX pipe technology platform. Thus, inherent pressing power of the material is nowadays of widespread use in various PEX pipe installations.

Polymerization of vegetable oils in diesel engines


Participating FunMat unit: LPT Markus Finne, Carl‐Erik Wilén, Juha‐Pekka Sundell and Niklas Haga

The purpose of this research work was to investigate the causes why the polymerization of vegetable oils occurs, when these are used as fuel in diesel engines. It is shown that these oils can polymerize under specific conditions, especially in the fuel injection system. During this polymerization a firm product is produced, which can cause serious problems. To elucidate why these problems occur laboratory experiments was done on different vegetable oils.

In laboratory surroundings the oils was reacted for a longer time under similar circumstances as in the fuel system, where these polymerization problems have appeared. These tests were performed in an Endeavor under slightly different conditions, whereupon the oils were analyzed accurately. The analyze instruments that were used were among others NMR and GC‐MS. In addition to this extensive tests on the oils were made in a DSC. Other things that were tested were for example the density of the oils from the different Endeavor runs. The solubility of a polymerization product from a power plant that was run on palmoil was also tested.

These tests showed that the oils seem to undergo an oxypolymerization, which is a polymerization process that can occur when oxygen is presented. This reaction showed to be very slow and it can also be delayed by using antioxidants in the oils. Factors that affect this kind of polymerization are for example temperature, reaction time and also the degree of unsaturation of the oils.

Collaboration: Wärtsilä Finland Oy Power Plants

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Characterization and production of PEX pipes


Participating FunMat unit: LPT Anton Holappa and Carl‐Eric Wilén

Pressurized polyethylene pipes have been used successfully for more than 50 years. In this work various production parameters have been optimized and various methods for fast characterisation of PEX pipes have been evaluated.

Collaboration: KWH‐pipe

Publication: Anton Holappa, Master Thesis 2010

Preparation of core‐shell latexes for paper coatings


Participating FunMat unit: LPT Mia Koskinen and Carl‐Eric Wilén

Core‐shell latexes, composed of a core covered by a shell, can be prepared by a two‐stage emulsion polymerization or seeded emulsion polymerization. The advantage of core‐shell latexes is their ability of having a composition of different monomers in core and shell, and thereby giving the particle tailor made properties for each application. Via core‐shell polymerization it is also possible to get otherwise incompatible monomers into one particle or to add functionality either into the core or shell.

A series of core‐shell latexes with a partially crosslinked hydrophilic polymer core and a hard hydrophobic shell of polystyrene were prepared in order to improve printability. Core‐shell latexes were prepared by a two‐stage emulsion polymerization by sequential addition of a monomer mixture of styrene, n‐butylacrylate and methacrylic acid using different crosslinkers to form the polymer core and styrene in the second stage to form the hard shell component. The prepared core‐shell latex particles were used as specialty plastic pigments for paper coating together with kaolin as the primary pigment. The runnability of paper coating formulation by either using a laboratory scale Helicoater or pilot scale JET‐coating machine was very good. The produced coated papers were printed on both sides employing a heat set web offset (HSWO) printer in order to study the quality of image reproduction in terms of print gloss, print mottle, print through, etc. To further improve latex particles a new polymerizable optical brightener 1‐[(4‐vinylphenoxy)methyl]‐4‐(2‐phenylethylenyl)benzene was inclueded during polymerization either into the core or shell. Overall the core‐shell latexes improved the print quality. Furthermore, the results demonstrate that by optimizing polymer composition one can affect optical properties of coated paper whereas the type of cross‐linker has a less pronounced influence on coated paper properties under investigation. By modifying paper coating it is possible to create a more favorable paper surface for functional printing or directly add functionality to it.

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Controlled living graft polymerization of ionic monomers onto irradiated polymer films by

Reversible Addition Fragmentation Chain‐Transfer Techniques


Participating FunMat unit: LPT Peter Holmlund and Carl‐Eric Wilén

The irradiation modification processing of thin polymer films has been extensively used at our laboratory thanks to the availability of an Electron beam apparatus. The modification processes are uncontrolled when using normal radical polymerization techniques. Uncontrolled graft‐co‐polymerization of ionomeric chains causes poor quality of the produced films when the graft co‐polymers have a high degree of branching and high polymerdispersity. A proposed solution to this is the different controlled polymerization techniques: Atom Transfer Radical Polymerization (ATRP), Nitroxi Mediated Polymerisation (NMP) and Reversible Addition Fragmentation Chain‐Transfer (RAFT). The ATRP and NMP techniques have been investigated and published earlier by our laboratory1,2, while RAFT technique is expected to bring added value to the controlled graft‐polymerization due to its simple application and robust character. Reversible Addition Fragmentation Chain‐Transfer polymerisation is a degenerative chain transfer process and is free radical in nature. it was first reported in 1996 by Rizzardo's group in Australia3. Most RAFT agents contain thiocarbonyl‐thio groups, and it is the reaction of polymeric and other radicals with the C=S that leads to the formation of stabilized radical intermediates. In an ideal system, these stabilised radical intermediates do not undergo termination reactions, but instead reintroduce a radical capable of reinitiation or propagation with monomer, while they themselves reform their C=S bond. The cycle of addition to the C=S bond, followed by fragmentation of a radical, continues until all monomer is consumed. Our aim is to produce good quality ion exchange polymer films combining mechanical strength with high ion conductivities for a multitude of applications such as electrolytes for Polymer Electrolyte Membrane Fuel Cells and Direct Methanol Fuel Cells. Other possible applications include semiconductor use in transistors.

Developing Advanced Biodegradable Lactic Acid‐Based Polymers by Step‐Growth

Polymerisation


Participating FunMat unit: LPT Saara Inkinen and Anders Södergård

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The aim of the project is to develop novel lactic acid based polymers using step‐growth polymerization (polycondensation) as the polymerization method. The first aim of the project is to improve the properties of poly(lactic acid) (PLA) for different applications by the incorporation of different, preferably biobased, comonomers into the polymer backbone. The second aim of the work is to develop the polycondensation process itself, as well as the characterization methods of these polymers, in order to increase the range of products polycondensation is suitable for.

Poly(lactic acid) can be prepared by direct polycondensation of lactic acid or by ring‐opening polymerization (ROP) of lactide. The industrial production of high molar mass PLA is currently based on ROP, even though high molar mass PLA can also be obtained by for example chain extension of LA‐based oligomers, step‐growth polymerization in a solvent or by azeotropic distillation techniques. However, also the ROP route involves a polycondensation step, and developing the polycondensation process is therefore also significant for the production of high molar mass PLA.

The primary polymerization method used in this project is polycondensation, since it is a cheap and simple method. The typical disadvantages of the polycondensation process involve the limited molar masses that can be obtained as well as different side reactions involving for example racemisation or intramolecular transesterification reactions leading to the formation of ring‐formed oligomers and lactide. However, optimising the polycondensation process parameters and conditions can be utilised to avoid the problems typically associated with the method and significantly improve the properties of the polymer, as shown by our group. Poly(lactic acid) produced by polycondensation has several potential end‐uses as hot melt adhesives, PLA stereocomplexes, precursors for linking, or low‐molecular weight additives for biopolymers, just to name a few.

Collaboration: The work was commenced by Saara Inkinen at Tate & Lyle Finland in 2006. The project is currently continued in collaboration with Associate Professor Anders Södergård (Laboratory of Polymer Technology, Åbo Akademi) and The Royal Institute of Technology (KTH), Stockholm, Sweden.

Publications: Saara Inkinen, Mikael Stolt, Anders Södergård, Effect of Blending Ratio and Oligomer Structure on the Thermal Transitions of Stereocomplexes Consisting of a D‐Lactic Acid Oligomer and Poly(L‐Lactide), Polymers for Advanced Technologies, in press (2010). Regnell Andersson, Sofia; Hakkarainen, Minna; Inkinen, Saara; Södergård, Anders; Albertsson, Ann‐Christine, Polylactide stereocomplexation leads to formation of more acidic hydrolysis products, Biomacromolecules, in press (2010). Saara Inkinen, Mikael Stolt, Anders Södergård, Readily Controllable Step‐Growth Polymerization Method for Poly(Lactic Acid) Copolymers Having a High Glass Transition Temperature, Biomacromolecules, in press (2010).

Development of Biodegradable Hot Melt Adhesives


Participating FunMat unit: LPT Saara Inkinen, Mia Borg and Carl‐Eric Wilén

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The laboratory of Polymer Technology is collaborating with Kiilto Oy (Tampere) in the development of biodegradable lactic acid‐based hot melt adhesives. The aim of the project is to develop a biodegradable and bio‐based hot melt formulation that could replace its oil‐based, non‐renewable alternatives. The traditional hot melt adhesives are typically based on fossil fuel‐based, non‐renewable polymers such as for example ethyl vinyl acetate (EVA). Especially in the packaging field, there is a continuous strive towards replacing non‐degradable materials with biodegradable ones and new materials are coming into the market at an increasing speed. However, no hot melt adhesive formulations that are both biodegradable and bio‐based are available at an industrial scale at the moment. The purpose of the project is thus to develop a commercially viable adhesive formulation for the use of the packaging industry. Biodegradable hot melt adhesives are potentially suitable for applications like sealing, single use packaging, paper and paperboard products, just to name a few.

Collaboration: Kiilto Oy, Tampere.

Modification of Polymeric Films – Ion‐ and Electron Conducting Materials (Part of Flex‐sense project)


Participating FunMat unit: LPT, DPh Carl‐Johan Wikman, Xe Xuehan and Carl‐Eric Wilén

The central themes during the year 2008 have been electron beam irradiated polymeric films as substrates for grafting, electrochromic polymeric materials and electron conducting and semiconducting polymeric materials.

One main objective of studies in 2008 has been to gain a better understanding of the parameters governing the fabrication of ion‐conducting membranes by electron‐beam (EB) pre‐irradiation induced grafting. The prepared membranes have been utilized in the production of novel ion‐modulated membrane transistors (MEMFET; Finnish patent application 20070063) that allow the integration of various devices on the same substrate in an unprecedented way. Since, limiting the ion conductivity in a membrane to locally conducting regions may be necessary in order to minimize cross‐talk and interference with the surrounding atmosphere also methods to prepare patterned membranes have been included in this study.

More specifically, the aims have been:

1. To investigate various process parameters such as radiation dose, masking, sulfonation conditions, membrane thickness, temperature, concentration of monomers and solvents effect on the structure and properties of the produced ion‐conducting membranes.

2. To design and prepare suitable ion‐conducting membranes for fabrication of MEMFETs of different configurations.

The year 2009 brought new views and ideas, and new aspects on their usability within FunMat. The work is continuing with new grafting methods and other possible routes to ion‐conducting membranes.

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Publications: Kaihovirta, N., Wikman, C‐J. Mäkelä T, Wilén, C‐E. R. Österbacka, “Self‐supported ion conductive membrane based transistors“, Advanced Materials, 21(24), 2520-2523 (2009) Österbacka, Ronald, Wilen, Carl‐Eric, Kaihovirta, Nikolai, Wikman, Carl‐Johan, Mäkelä, Tapio, "Components and circuit arrangements including at least one organic field‐effect transistor" , Paptent application WO2010010233 Österbacka, Ronald, Wilen, Carl‐Eric ,Backlund Tomas, Kaihovirta, Nikolai, " Organic field‐effect transistor" US2010032661 Nikolai Kaihovirta, Harri Aarnio, Carl‐Johan Wikman, Carl‐Eric Wilen, Ronald Österbacka, "Improved device stability by adding sterically hindered phenol in low‐voltage OFETs" submitted to Advanced Materials Nikolai Kaihovirta, Tapio Mäkelä, Xuehan He, Carl‐Johan Wikman, Carl‐Eric Wilen, Ronald Österbacka “Printed all‐polymer electrochemical transistor on patterned ion conducting membrane", submitted to Organic Electronics Nikolai Kaihovirta, Harri Aarnio, Carl‐Johan Wikman, Carl‐Eric Wilen, Ronald Österbacka, "The effects of mositure in low‐voltage ion conductive membrane based organic transistors" submitted to Advanced Functional Materials

Optimal binder usage in coated paper (OPTIBIND)


Participating FunMat unit: LPT, LPCC Robert Nilsson, Mahdi Pahlevan and Carl‐Eric Wilén

Today, the most commonly used pigment dispersants are based on polyacrylate salts that have been prepared by classical free radical polymerization. Although the classical free radical polymerization technique is characterized by many attractive features it also has some severe limitations, inherent to its mechanism. Especially, it is difficult to control molar masses and polydispersities as well as to introduce defined end‐groups, or to prepare special architectures such as block copolymers, star or comb‐like structures by classical free radical polymerization techniques. In recent years, it has been showed that these limitations can successfully be circumvented by using living (or controlled) free radical techniques such as NMRP (nitroxide‐mediated radical polymerization), ATRP (atom transfer radical polymerization) or RAFT (reversible addition‐fragmentation chain transfer polymerization). As a consequence of this and to be able to precisely control molecular weight and polydispersities as well as to have the option to prepare complex architectures we decided to prepare Na‐polyacrylate‐based dispersants by using RAFT process instead of utilizing classical free radical polymerization techniques.

Our future plan has been to conduct a series of polymerizations of AA by using the RAFT technique in order to obtain monodisperse polyacrylate salts with a range of molecular weights. The range of molecular weights was selected on the basis of the modeling results by University of Jyväskylä, Laboratory of Applied Chemistry. The polymerization products were then analyzed by using GPC, NMR,

42

HPLC and by rheological measurements. After this, the dispersants was delivered to Åbo Akademi, Laboratory of Paper Coating and Converting for further testing. After the role of molecular weight of polyacrylate salts had been established the polymerization was expanded by introducing various functional monomers (e.g. in order to prepare block copolymers, branched polymers, etc.) that further altered the interaction between pigment‐dispersing agent‐ binder. The functional groups and polymer structures was prepared based on suggestions from steering group members, molecular modeling and literature.

Collaboration: industry

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3.2.3 Syntheses and properties of functional polymeric materials Laboratory of Polymer Chemistry, University of Helsinki

During the reporting period January 2009 – April 2010, the main research topics related to FunMat have been hybrid nanocomposite materials, new self‐assembling polymers based on various calixarenes and polymerizable ionic liquids, thermoresponsive and thermoassociating polymers, as well as fluoropolymers. Wood chemistry is increasing. Funding from the Academy of Finland to a project concerned with molecular modeling on polyelectrolyte dendrimers ended in the end of 2009. However, the researcher involved in this project is finalizing his PhD at present.

Hybrid nanocomposite materials 1: metal nanoparticles stabilized with polymers Main funding: FunMat and LPC Participating FunMat unit: LPC Petri Pulkkinen, Jun Shan, Jukka Niskanen Gold, silver, and copper nanoparticles have been prepared which have been grafted/stabilized with polymers or low molar mass substances. Gold has been grafted mainly by a thermoresponsive polymer poly(N‐isopropylacylamide), PNIPAM or NIPAM oligomers. The main interest has been on the environmental effects on the optical properties of the particles, but also on the thermal behaviour of surface‐grafted polymer chains.

During the reporting period, a study on well‐fractionated NIPAM oligomers as free chains in water and as brushes grafted on gold nanoparticle surfaces was published which shows the striking difference between the thermal beahavior of the free and bound oligomers. Monolayers of Au‐PNIPAM particles on water surface were characterized using neutron reflectometry, and a detailed thermal analysis of PNIPAM grafts was conducted.

Polymer‐grafted silver nanoparticles have been prepared to be used in antibacterial coatings. Soft, sticky coatings were prepared which have been shown to release only silver ions. The research continues in collaborating laboratories (Helsinki, Madrid).

The preparation of copper particles is challenging: the particles need to be effectively protected against oxidation. Nanoscaled copper particles have sintering temperatures low enough to be sintered on paper. Sintering tests have been initiated in collaboration with other project groups. The first successful particles were prepared in water using low molar mass and polymeric imines as stabilizing agents. At present, the effect of various polymers on particle properties is investigated. We compare commercial branched poly(ethyleneimine), PEI, with a linear PEI and with a block copolymer PEI‐PEO.

Recently, syntheses of metal nanoparticles where calixarenes are covalently bound to the surfaces have been initiated. Because of the well‐known host‐guest properties of calixarenes, these may turn out to be interesting building blocks for novel supramolecular structures.

Collaboration: Åbo Akademi, Laboratoire Leon Brillouin, Saclay, Vrije Universiteit Brussel, University of

Montreal, KCL/VTT, TKK

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Publications: Maijala, Juha; Merta, Juha; Shan, Jun; Tenhu, Heikki, Novel particles and method of producing the same, PCT Int. Appl. (2009), WO 2009040479 A1 20090402. Shan, Jun; Zhao, Yiming; Granqvist, Niko; Tenhu, Heikki, Thermoresponsive Properties of N‐Isopropylacrylamide Oligomer Brushes Grafted to Gold Nanoparticles: Effects of Molar Mass and Gold Core Size, Macromolecules (2009), 42(7), 2696‐2701. Pulkkinen, Petri; Shan, Jun; Leppänen, Kirsi; Kansakoski, Ari; Laiho, Ari; Järn, Mikael; Tenhu, Heikki, Poly(ethylene imine) and Tetraethylenepentamine as Protecting Agents for Metallic Copper Nanoparticles, ACS Applied Materials & Interfaces (2009), 1(2), 519‐525. Lay‐Theng Lee, Heikki Tenhu et al., Tuning the structure of thermosensitive gold nanoparticle mono‐layers, The Journal of Physical Chemistry B, (2009), 113(29), 9786‐9794. Bruno Van Mele, Heikki Tenhu et al., Demixing and Remixing Kinetics in Aqueous Dispersions of Poly(N‐isopropylacrylamide) (PNIPAM) Brushes Bound to Gold Nanoparticles Studied by Means of Modulated Temperature Differential Scanning Calorimetry, Macromolecules, (2009), 42(14), 5317‐5327. Niskanen, Jukka; Shan, Jun; Tenhu, Heikki; Jiang, Hua; Kauppinen, Esko; Barranco, Violeta; Pico, Fernando; Yliniemi, Kirsi; Kontturi, Kyoesti , Synthesis of copolymer‐stabilized silver nanoparticles for coating materials, Colloid and Polymer Science (2010), 288(5), 543‐553.

Hybrid nanocomposite materials 2: Grafting of nanoclays

Main funding: FunMat and EU project MUST Participating FunMat unit: LPC Mikko Karesoja, Jukka Niskanen

Nanosized montmorillonite has been grafted with an amorphous polymer by ATRP reactions in order to

prepare MMT containing composites with good film forming properties. Also other clays, as halloysite

and sepiolite have been tested. At present, clays are also grafted with both water‐ and organosoluble

polymers to be used as carriers in anticorrosive coatings (EU FP7 project). Surface derivatized

mesoporous particles obtained from other project groups have been prepared (manuscript under

preparation).

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Figure above presents mesoporous silica nanoparticles (obtained from Åbo Akademi) which have been

grafted with poly(vinylcaprolactam‐b‐ethyleneoxide). PVCL is a thermoresponsive polymer which

collapses upon increasing temperature. PEO prevents the precipitation of the particles. Particles might

find use as intelligent carriers in FunMat.

Collaboration: ÅA, 20 industrial and academic partners in the EU project.

Publication: Karesoja, Mikko; Jokinen, Harri; Karjalainen, Erno; Pulkkinen, Petri; Torkkeli, Mika; Soininen, Antti; Ruokolainen, Janne; Tenhu, Heikki, Grafting of montmorillonite nano‐clay with butyl acrylate and methyl methacrylate by atom transfer radical polymerization: Blends with poly(BuA‐co‐MMA), Journal of Polymer Science, Part A: Polymer Chemistry (2009), 47(12), 3086‐3097.

Amphiphilic star polymers

Main funding: FunMatAcademy of Finland, ESPOM, DAAD Participating FunMat unit: LPC Anu Koponen, Katriina Kalliomäki, Felix Plamper, Mikko Mänttäri, Sami Hietala, Szymon Wiktorowics

Star polymers are synthesized based on [4], [6], and [8] calixarenes. In the two latter cases, amphiphiles are synthesized with ATRP reactions growing amphiphilic polymers from calixarene units. The amphiphiles are diblock copolymers consisting of a hydrophobic (either glassy or soft) block and of a hydrophilic thermoresponsive block (either PNIPAM or PDMAEMA). These polymers form micelles in water and their use as carriers for low molar mass substances are studied. The added substances are either wood preservatives or molecules/ ions applicable in non‐linear optics. Calix[4]arene is derivatized by first locking its cone conformation with adequate substitution. Next, polymers are grown of these entities by first nitrating the macrocycles and then by reductive coupling.

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Miktoarm stars and pear‐necklace polymers have been synthesized based on dimethylaminoethylmethacrylate and PEO. The polymers form micelles/vesicles in water either under uv‐irradiation (irreversible process) or in electric field (a reversible process).

Rheological properties of aqueous star polymers have been studied. Dr Felix Plamper finished his post doctoral period in Helsinki in 2009 and Mikko Mänttäri has since that been involved in another project.

Collaboration: VTT, Institute of Macromolecular Compounds, RAS, Petersburg, Universität Bayreuth

Publications: Plamper, Felix A.; McKee, Jason R.; Laukkanen, Antti; Nykänen, Antti; Walther, Andreas; Ruokolainen, Janne; Aseyev, Vladimir; Tenhu, Heikki, Miktoarm stars of poly(ethylene oxide) and poly(dimethylaminoethyl methacrylate): manipulation of micellization by temperature and light, Soft Matter (2009), 5(9), 1812‐1821.

Plamper, Felix A.; Reinicke, Stefan; Elomaa, Matti; Schmalz, Holger; Tenhu, Heikki, Pearl Necklace Architecture: New Threaded Star‐Shaped Copolymers, Macromolecules (2010), 43(5), 2190‐2203. Plamper, Felix A.; Murtomaki, Lasse; Walther, Andreas; Kontturi, Kyosti; Tenhu, Heikki ,e‐Micellization: Electrochemical, Reversible Switching of Polymer Aggregation Macromolecules (2009), 42(19), 7254‐7257. Hietala, Sami; Strandman, Satu; Järvi, Paula; Torkkeli, Mika; Jankova, Katja; Hvilsted, Soren; Tenhu, Heikki, Rheological Properties of Associative Star Polymers in Aqueous Solutions: Effect of Hydrophobe Length and Polymer Topology, Macromolecules (2009), 42(5), 1726‐1732. A.V. Tenkovtsev, M.M. Dudkina, L.I. Scherbinskaya, V. Aseyev, H. Tenhu, Star‐Shaped Macromolecules with Calixarene Core and Neutral Amphiphilic Block Copolymer Arms: New Hosts for Ions, Polymer, accepted.

Coarse grained modeling of stars and their complexes

Main funding: Academy of Finland, RAS Participating FunMat unit: LPC Anna Zarembo, Sergey Larin

Coarse grained methods have been used to study the associating properties of amphiphilic star polymers in water, as well as interactions of charged dendrimers with linear polyelectrolytes. A PhD thesis on this topic is expected to be finalized in 2010. The laboratory joined a COST action where the use of charged dendrimers in the prevention/healing of degenerative diseases (as Alzheimer) are studied both experimentally and theoretically. To boost this project we are actively looking for Finnish or European funding to employ Dr. Igor Neelov (RAS, Petersburg) in Helsinki.

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An anionic dendrimer is complexed with a linear

polycation

Collaboration: Institute of Macromolecular Compounds, RAS, Petersburg, 12 partners in the COST

project.

Publications: Larin, Sergey; Lyulin, Sergey; Lyulin, Alexey; Darinskii, Anatoly, Computer simulations of inter‐polyelectrolyte complexes formed by star‐like polymers and linear polyelectrolytes, Macromolecular Symposia (2009), 278(Molecular Order and Mobility in Polymer Systems), 40‐47. Larin, Sergey V.; Darinskii, Anatolii A.; Lyulin, Alexey V.; Lyulin, Sergey V, Linker Formation in an Overcharged Complex of Two Dendrimers and Linear Polyelectrolyte, Journal of Physical Chemistry B (2010), 114(8), 2910‐2919. Larin, Sergey V.; Pergushov, Dmitry V.; Xu, Youyong; Darinskii, Anatoly A.; Zezin, Alexander B.; Mueller, Axel H. E.; Borisov, Oleg V, Nano‐patterned structures in cylindrical polyelectrolyte brushes assembled with oppositely charged polyions , Soft Matter (2009), 5(24), 4938‐4943. Larin, S. V.; Lyulin, S. V.; Lyulin, A. V.; Darinskii, A. A., Inversion of dendrimers charge in complexes with linear polyelectrolytes in low pH solutions, Vysokomolekulyarnye Soedineniya, Seriya A i Seriya B (2009), 51(4), 666‐676.

Thermoresponsive polymers

Main funding: Tekes, Academy of Finland, FunMat, LPC Participating FunMat unit: LPC Several of the above mentioned researchers, and Erno Karjalainen

This topic partially overlaps with the previous ones because we have used thermoresponsive PNIPAM in several applications. However, several other polymers based on PNIPAM or polyvinylcaprolactam have been prepared as well. The focus has been on one hand on the self‐assembling properties of aqueous

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polymers, and on the other, on ATRP and RAFT polymerization reactions. One of the important findings to be mentioned here is that it has been possible to control not only molar mass but also stereoregularity of PNIPAM. This is interesting, because isotactic PNIPAM is not water soluble. Block tripolymers combining atactic and isotactic blocks are amphiphilic and strongly associating; under certain conditions they form gels. Block polymers have also been studied to control the crystallization of certain drugs.

A new topic concerns the polymerization of (meth)acrylic derivatives on some imidazolium based ionic liquids. Block copolymers have been prepared where the other block consists of the polymeric ionic liquid (PIL) and the other is PNIPAM. The counterion in the PIL has been chosen so that the block is not water soluble. Thus, micelles can be formed with a PIL core. These may be expected to be used as carriers of various substances of low solubility, or even as nanoreactors in water. In future, by ion exchange we plan to render the PIL blocks water‐soluble. Funding for this project (Tekes) finally started in the beginning of 2010.

Collaboration: Helsinki University of Technology (Aalto University), Åbo Akademi, Copenhagen University, several Finnish companies Publication: Aseyev V., Tenhu H., Winnik Francoise M., Non‐ionic thermoresponsive polymers in water (a review), Adv. Polym. Sci. (2010), DOI:10.1007/12_2010_57

Cl

O+ Br

OH O

O

Br

N NO

ON N

+

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+

BF4-

RT, CH2Cl2,

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NaBF4(aq)

40 °C

S

S

O

N

N

O

N

O

OH

+

ACPA,CPA

MeCN, 75 °C

NHOO

N

N

O

S

N

O

OH

S

+

BF4-

ACPA,NIPA

MeCN,Dioxane, 60 °C

n

n m

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Fluoropolymers

Main funding: Industry, a private foundation Participating FunMat unit: LPC Lauri Valtola, Sami Hietala

Several of low molar mass fluorinated surfactants used in chemical industries are toxic, and especially from the REACH view point, their replacement with polymeric ones is beneficial. Using ATRP technique, several new fluorinated and semifluorinated polymers have been synthesized. Recently, superhydrophobic surfaces have been prepared by e‐spinning the fluoropolymers. Importantly, it has been observed that even a small amount of fluoropolymer may turn even polystyrene surface superhydrophobic. At present, the use of the polymers as emulsifiers in supercritical CO2 is studied.

Water droplet on an electrospun surface

Collaboration: Borealis Polymers (finished during the period), other laboratories in the Chemistry Department in Helsinki Publication: Valtola, Lauri; Hietala, Sami; Tenhu, Heikki; Denifl, Peter; Wilen, Carl‐Eric, Association behavior and properties of copolymers of perfluorooctyl ethyl methacrylate and eicosanyl methacrylate,Polymers for Advanced Technologies (2009), 20(3), 225‐234. Valtola, Lauri; Koponen, Anu; Karesoja, Mikko; Hietala, Sami; Laukkanen, Antti; Tenhu, Heikki; Denifl, Peter, Tailored surface properties of semi‐fluorinated block copolymers by electrospinning Polymer (2009), 50(14), 3103‐3110.

Water dispersible conducting polymers

Main funding: Finnish Funding Agency for Technology and Innovation (Tekes) Participating FunMat unit: LPC Sami‐Pekka Hirvonen

This project started as a part of a larger one, “Organic solar cell” coordinated by Professor Helge Lemmetyinen (Tampere University of Technology). The aim was to prepare environmentally friendly

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aqueous dispersions of conducting polymers to be used as conducting layers in photovoltaic cells. The work started by the preparation of water‐dispersible polyaniline derivatives, for which an international patent was filed together with Finnish company Panipol in 2008. The polymers being prepared at the moment are derivatives of poly(benzimidazol‐benzofenantroline), BBL. Water dispersibility in both cases is obtained by binding short polyethyleneoxide chains to the rigid polymers. The electric properties of the polymers are studied together with Åbo Akademi and the University of Turku (UTU).

Collaboration: ÅA, UTU, Tampere University of Technology, Panipol

Publication: Two manuscripts under preparation, on the synthesis and electric properties of BBL

derivatives

Natural Polymers ‐ Polymer Tailoring from Renewable Sources

Main funding: Academy of Finland, Finnish Funding Agency for Technology and Innovation (Tekes), Industry and the Forest Cluster

Participating FunMat unit: LPC Miia Hiltunen, Sirkka Liisa Maunu, Mikko Mänttäri, Helena Parviainen, Pirita Uschanov, Tommi Virtanen

Main themes in this research have been the ultrastructure of cellulose fibers obtained from various resources. The effects of modification procedures for cellulose fibre materials are studied in order to make them accessible to chemical reactions for various products. Cellulose has been grafted with synthetic water soluble polymers using RAFT and ATRP reactions, and properties of the products have been studied. The water soluble graft copolymers based on cellulose have a great potential for applications in biomedicine and biotechnology and as new cellulose based chemicals for paper chemistry. Cellulose is derivatised not only on a molecular level but also nanofibers and regenerated cellulose are modified e.g. with long chain fatty acids. Water‐borne binders for wood coatings are developed using alkyd‐acrylate hybrids based on tall oil.

Collaboration: KCL, VTT, Partners in FuBio (Forest Cluster‐SHOK) and Partners in WW‐Net project

‘ReCell’ from Sweden and Germany.

Publications: Hiltunen, Miia; Riihelä, Simon; Maunu, Sirkka Liisa, New Associative EHEC‐g‐PAam Copolymers: Their Syntheses, Characterization and Rheological Behaviour, J. Polym. Sci. Part B: Polym. Phys., 47 (2009) 1869‐1879. Matilainen, Laura; Maunu, Sirkka Liisa; Pajander, Jari; Auriola, Seppo; Jääskeläinen, Ilpo; Lambertsen Larsen, Kim; Järvinen, Tomi; Jarho, Pekka, The Stability and Dissolution Properties of Solid Glucagon/�‐cyclodextrin powder, Eur. J. Pharm. Sci., 36 (2009) 412‐420. Kuutti, Lauri; Putkisto, Kaisa; Hyvärinen, Sari; Peltonen, Soili; Koivunen, Kimmo; Paulapuro, Hannu; Tupala, Jere; Leskelä, Markku; Virtanen, Tommi; Maunu, Sirkka Liisa, Starch‐Hybrid Fillers for Paper, Nordic Pulp and Paper Research Journal, (2010), submitted

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Virtanen, Tommi; Maunu, Sirkka Liisa, Quantitation of a Polymorphic Mixture of an Active Pharma‐ceutical Ingredient with Solid State 13C CPMAS NMR Spectroscopy, Int. J. Pharm., (2010), submitted.

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3.2.4 Substrate activity and compatibility for functional materials Laboratory of Paper Coating and Converting (LPCC)

The requirements that potential future smart and intelligent paper applications set for natural fiber‐

based substrates are different from, and often more demanding, when compared to traditional

publication papers. A successful production of a functional device by e.g. a printing process requires a

stable surface that is ultra‐smooth, has appropriate adhesion properties, is chemically inert, have

controlled wettability and barrier properties and acceptable mechanical properties. These requirements

and their combinations are not inherent properties of paper and cannot be met with currently available

paper grades.

The objective of this project is to understand the requirements and control the compatibility between

the various materials that when combined result in new value‐added functional concepts. Three main

areas of research are envisioned: (a) modification and control of the properties of natural fiber‐based

substrates in order to make them compatible with the added functionality concepts, (b) clarification

and control of the processability of functional (raw) materials as defined by the surface treatment,

coating or printing processes that are used to assemble the novel functional surfaces, sensors and

devices, and (c) embedding of new functionality into or onto the substrate.

An important goal is to understand setting mechanisms of novel inks that are used for printed

functionality. Understanding of mechanisms and interactions between ink components and solvents and

print substrates is needed for successful printability and utilization of fiber‐based products for printed

functionality. Detailed and versatile characterization of surface chemical and topographical properties of

the studied surfaces and interfaces is an important part of the research.

One approach to improve substrate compatibility is to adapt techniques already in use for traditional

surface treatment, e.g., pigment coating, surface sizing and calendering. In addition, nanoparticle‐

stabilized dispersions/emulsions will be utilized as compatibilizers and adhesion promoters of substrate

coatings. One of the specific goals is to understand the prerequisites for incorporating biofunctional

coatings and sensor elements to printable electronic devices.

The instrumentation has been actively upgraded with new test printers (offset, gravure, flexo, inkjet)

and coaters (reverse‐gravure, curtain, spray), laboratory‐scale calenders, ink‐surface interaction testers

(ISIT), contact angle instrumentation (multidispenser system) and microscopy (multimode AFM).

A number of publications not listed in Annual Report 2008 are included in the reference list.

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Characterization and Control of Pigment Coating Structures(C‐Coat)


Participating FunMat units: LPCC, DPC Liisa Sinervo, Thomas Byholm, Marie Käld, Andreas Lemström, Niklas Nylund, Christoffer Stoor, Otto Järvinen, Jani Kniivilä, Joakim Järnström, Jouko Peltonen, Martti Toivakka Most physical and functional properties pigment coated papers are controlled by the microscopic

structure of the coating layer. The objective of the project is to increase our understanding of the

interrelations between coating raw materials, the microscopic porous structures resulting from these,

and the end‐use properties of coated paper. The main areas of research include physical and surface

chemical characterization of two and three dimensional coating layer structures, optical properties of

coatings and liquid penetration in porous structures. The results of the project range from coating

surface characterization on different length scales to computer‐based experimentation and prediction of

optical and liquid absorption properties of coatings.

Collaboration: Helsinki University/Observatory, University of Jyväskylä/Department of Physics, ABB Oy,

Ciba Specialty Chemicals Oy, M‐real Oyj, Metso Paper Oy, Omya Oy, Specialty Minerals Nordic Oy, Stora

Enso Oyj and UPM‐Kymmene Oyj.

Publications: Parvez Alam, Thomas Byholm, Jani Kniivilä, Liisa Sinervo, and Martti Toivakka,”Calculating the

permeability of model paper coating structures comprising incongruent particle shapes and sizes”,

Microporous and Mesoporous Materials, volume 117, number 3, pages 685‐688, (2009).

T. Byholm, M. Toivakka, and J. Westerholm,” Effective packing of 3‐dimensional voxel‐based arbitrarily

shaped particles”, Powder Technology, volume 196, pages 139‐146, (2009).

Joakim Järnström, Petri Ihalainen, Andreas Lemström, Martti Toivakka, and Jouko Peltonen,”The

influence of different roughness scales of pigment coated papers on print gloss”, Nordic Pulp and Paper

Research Journal, volume 24, number 3, pages 327‐334, (2009).

J. Preston, M. Toivakka, P. Heard, and G. Chinga‐Carrasco,” Coated paper microstructure: Particle shape

‐ microstructure interrelations”, Proceedings of TAPPI Coating and Graphic Arts Conference, TAPPI Press,

Atlanta GA, (2009).

Improved Printability through Atmospheric Pressure Plasma Surface Treatment (Plastek)


Participating FunMat unit: LPCC Maiju Pykönen, Martti Toivakka

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The project evaluates suitability and the (industrial) applications of the atmospheric pressure plasma

treatment for in‐line roll‐to‐roll processing, and aims at increasing our understanding of the effects of

plasma treatment of natural fiber‐based substrates. Of specific interest is the improvement of the offset

and inkjet printability of uncoated and coated papers and paper boards by atmospheric pressure plasma

surface treatment. In addition to plasma activation, the possibility to influence the printability through

use of plasma deposition that can create atomic monolayer surfaces with desired surface chemical and

energy properties is explored.

Collaboration: Tampere University of Technology, VTT, Stora Enso Oyj, UPM‐Kymmene Oyj. Vetaphone,

Millidyne and Omya Oy

Publications: Maiju Pykönen, Hanna Silvaani, Janet Preston, Pedro Fardim, and Martti Toivakka,”Plasma activation induced changes in surface chemistry of pigment coating components”, Colloids and Surfaces A: Physicochemical and Engineering Aspects, 352, 103‐112, (2009). Maiju Pykönen, Kenth Johansson, Marjorie Dubreuil, Dirk Vangeneugden, Göran Ström, Pedro Fardim, and Martti Toivakka, “An attempt to reduce dampening water absorption using hydrophobic plasma coatings”, TAGA 61st Annual Technical Conference, (2009). Maiju Pykönen, Kenth Johansson, Johan Larsson, Pedro Fardim, and Martti Toivakka, Improved flexography printing of wax‐coated paperboard through atmospheric pressure plasma treatment, PTS Coating Symposium, (2009). Hanna Silvaani, Plasma activation of pigment coated papers and its effect on offset printability, MSc thesis, Åbo Akademi, (2009). M. Pykönen, K. Johansson, R. Bollström, P. Fardim, and M. Toivakka, Influence of surface chemical composition on UV‐varnish absorption into permeable pigment‐coated paper, Ind. Eng. Chem. Res., 49:2169–2175, (2010). M. Pykönen, K. Johansson, M. Dubreuil, D. Vangeneugden, G. Ström, P. Fardim, and M. Toivakka, Evaluation of plasma‐deposited hydrophobic coatings on pigment‐coated paper for reduced dampening water absorption, Journal of Adhesion Science and Technology, 24:511–537, (2010).

Towards Novel and Cost‐Efficient Coating Binder Systems ‐ Optimal Binder Usage in Coated

Paper (OptiBind)


Participating FunMat units: LPCC, LPT Parvez Alam, Farid Touaiti, Natalie Fern, Mahdi Pahlevan, Robert Nilsson, Carl‐Eric Wilén, Martti Toivakka The project aims at increasing the understanding of binder functionality in pigment coatings. In order to

ensure adequate surface strength of pigment coated paper for finishing and end‐use purposes, a

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sufficient amount of binder has to be used. When reducing binder levels in pigment coatings below a

certain threshold to reduce costs, various problems appear that are related to mechanical failure in the

coating layer. Solutions to the problem are searched through experiments that elucidate, at the

molecular level, the interactions between binders, dispersants and coating pigments, and development

and testing of modified pigment or latex dispersants/additives that improve the interfacial strength

between coating pigments, binders and fibers.

Collaboration: University of Jyväskylä, BASF Oy, Dow Suomi Oy, Imerys Minerals Oy, SAPPI Finland 1 Oy,

Stora Enso Oyj and UPM‐Kymmene Oyj

Publications: Parvez Alam and Martti Toivakka, ” Computational techniques to relate the mechanical properties of

nano‐porous particle‐polymer composites with their microstructural characteristics”, International

Conference on Mechanical Engineering (2009).

Parvez Alam, Martti Toivakka, Roger Carlsson, Pekka Salminen, and Stefan Sandås, “ Balancing between

fold‐crack resistance and stiffness”, Journal of Composite Materials, volume 43, number 11, pages 1265‐

1283 (2009).

M. Toivakka, R. Carlsson, P. Alam, S. Sandås, P. Salminen, and J. Natalense, “Modelagem e estudos

experimentais para otimização do balanço entre resistência a falha na dobra e rigidez ao arqueamento

em papéis revestidos com múltiplas camadas. Parte 1: Introdução e estudos de modelagem / parte 2:

Estudos experimentais”, Proceedings of ABTCP‐PI 2009 ‐ 42nd Pulp and Paper International Congress,

ABTCP, São Paulo, Brazil, (2009) (in Portuguese).

Optimisation of Blade Geometry for Coating of Fine Paper Using Wear‐Resistant Blades


Participating FunMat unit: LPCC Parvez Alam, Christoffer Stoor, Prem Kumar Seelam, Martti Toivakka

The project aims at understanding the blade mechanics in the blade coating of paper, and proposing

new, improved blade geometries for coating of board and fine paper. A computer‐based complex inter‐

coupled multi‐physics model was developed to account for backing roll, base paper, pigment filter cake

and, if desired, polymeric blade surface compression. Based on numerical simulations of pigment

coating suspensions modelled with one‐phase fluid of non‐Newtonian rheology, a better understanding

of the blade mechanics have been obtained.

Collaboration:

Publication: Parvez Alam and Martti Toivakka,” Deflection and plasticity of soft‐tip beveled blades in paper coating operations”, Materials and Design, volume 30, pages 871‐877 (2009).

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Microscopic Modeling of Coating Layer Consolidation

Main funding: Oy Keskuslaboratorio ‐ Centrallaboratorium Ab, PaPSaT Participating FunMat unit: LPCC Anders Sand, Martti Toivakka The project aims at (a) clarifying what kind of microscopic structures exist in pigment coating colors during consolidation, and (b) predicting how the wet state coating structure is reflected in the final dried coating layer structure and related coated paper end‐use properties. The project utilizes numerical tools developed at the laboratory to model concentrated colloidal suspensions and to follow the microscopic motion of individual particles in the consolidating coating layer. The results have clarified relevance of the various theories proposed in literature to control consolidation of pigment coating layers. Collaboration: VTT, KCL Publications: Anders Sand, Martti Toivakka, and Tuomo Hjelt,” Influence of colloidal interactions on pigment coating layer structure formation”, Journal of Colloid and Interface Science, volume 332, pages 394‐401, Jan, (2009). Anders Sand, Tuija Nopola, Tuomo Hjelt, and Martti Toivakka,” A particle motion model for the study of consolidation phenomena”, Computers and Chemical Engineering, volume 33, pages 1227‐1239 (2009). Anders Sand, Jani Kniivilä, Martti Toivakka, and Tuomo Hjelt, “Structure formation mechanisms in consolidating pigment coating layers ‐ simulation and visualization”, Computational Materials Science (submitted) (2009). Anders Sand, Martti Toivakka, and Tuomo Hjelt, “Colloidal interactions and particle clustering in consolidating pigment coating layers”, Proceedings of 2009 Papermaking Research Symposium (CD), Kuopio, Finland (2009). Anders Sand, Jani Kniivilä, Martti Toivakka, and Tuomo Hjelt, “Microstructure development in consolidating pigment coatings studied by numerical simulation”, Proceedings of European Coating Symposium 2009, Karlsruhe, Germany, pages 69‐72 (2009). Anders Sand, “Microscopic simulation of pigment coating consolidation”, PhD‐thesis, Åbo Akademi (2010).

Tailored nanostabilizers for biocomponent interfaces (Taina)


Participating FunMat units: LPCC, DPC Helka Juvonen, Manuela Tigerstedt, Jouko Peltonen

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The objective of the project Taina (VTT, TKK, ÅAU) has been to develop technologies for modification

and assembly of biopolymers, i.e. proteins or selected carbohydrates suitable as nanostabilizers of

sensitive biocomponents. Special emphasis is concentrated on chemo‐enzymatic functionalization of

biopolymeric building blocks in order to create enhanced self‐assembly, integrity and performance of

nanoparticles. These functional nanoscale particles will be exploited in food systems and for tailored

barrier/sensing systems in food packages. A wide range of proteins (e.g. β‐lactoglobulin, whey protein,

casein, coactosin) and peptides have been studied by their coating and film formation properties, and

the possibility to modify their functionality by enzymes (e.g. laccase, tyrosinase). Besides morphology,

AFM and e.g. ToF‐SIMS studies have yielded information about the reaction mechanisms between

enzymes and proteins.

Collaboration: VTT, TKK, YKI (Tukholma), Lumene Group, Billerud, Uniq Bioresearch

Publication: H. Juvonen, M. Smolander, H. Boer, J. Pere, J. Buchert, J. Peltonen, “Enzymatically polymerized casein films for food packaging materials”, submitted.

Good quality for wood and fibre‐based materials ‐ Nano‐mediated mega value for wood and

fibre based products (NaMeWood)


Participating FunMat units: LPCC, DPC Shaoxia Wang, Jouko Peltonen The properties of wood and laminated wood composite material produced can be modified by different nanostructures, such as nanoparticle additives and nanocoatings. The properties to be improved are controlled water vapor permeability and release of wood based VOCs, moisture resistance, resistance against UV radiation and weather, soil resistance as well as mechanical durability of wood surfaces (scratch resistance and surface hardness). Nanotechnology and nanostructures enable adaptable coating solutions for board and fine paper products; better converting properties for board and repellent, anti‐fouling characteristics for paper products (for instance wall papers, security papers). Paper printability properties can also be modified by introducing of nanostructures to paper surface compositions.

The overall objective of the research is to enhance competitiveness of wood, wood composite, pulp and

paper materials in global markets.

Collaboration: VTT, Teknos Oy, Millidyne Oy, Koskisen Oy, Stora Enso Oyj, and Stora Enso Laminating Paper Oy

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Surface proximity assay (Supra II)

Main funding: Finnish Funding Agency for Technology and Innovation (Tekes) Participating FunMat units: DPC, LPCC Sari Pihlasalo, Jouko Peltonen The aim of the research projects has been to construct a homogeneous assay principle on a dyed planar surface for high‐throughput β2‐adrenergic receptor screening purposes. The methodology relies on a planar surface containing dye layers of nanometer thickness and energy transfer between the surface and a soluble molecule in solution recognizing a specific compound of interest. The interactions have been studied on molecular level by using probe microscopy techniques with the goal of distinguishing specific interactions for non‐specific ones. The bioaffinity reaction occurs directly on a lipid layer coated over the planar dye‐surface within a specified hydrophilic/hydrophobic area. Lipid monolayers and bilayers (< 6 nm) have been formed on the developed planar surface using Langmuir Blodgett and Schaefer techniques. β2‐adrenergic receptors have been successfully immobilized on the planar surface through fusion of receptor vesicles or direct coupling during the lipid film formation. Functional assay has been studied and conducted using energy transfer principle. Collaboration: University of Turku, University of Oulu, KSV Instruments, Innotrac Diagnostics, Perlos,

Releco‐Coating

Publications: A.Valanne, J. Suojanen, J. Peltonen, T. Soukka, P. Hänninen and H. Härmä, “Multiple sized Europium(III) chelate‐dyed polystyrene particles as donors in FRET – an application for sensitive protein quantification utilizing competitive adsorption”, Analyst, 5, 980‐986 (2009). S. Pihlasalo, M. Hara, P. Hänninen, J.P.Slotte, J. Peltonen and H. Härmä,” Liposome based homogeneous luminescence resonance energy transfer”, Analytical Biochemistry, 384, 231‐237 (2009).

Strength, role and removal of nanoparticle‐based nonspecific binding in bioaffinity assay and bioimaging systems using electrostatic transferor (Eltrans) Main funding: Academy of Finland Participating FunMat unit: DPC Anni Määttänen, Jouko Peltonen Increasing number of highly luminescent nanoparticle labels in bioaffinity assays and bioimaging has become problematic in respect to nonspecific binding of the labels coupled with biomolecules. The larger size of nanoparticles and the high number of biomolecules on the particulate labels and, therefore, increased number of interactions compared to soluble biomolecules are the primary reasons for higher nonspecificity. The aim of the proposed project is to study and understand fundamental phenomena behind nonspecific binding of nanoparticle labels in bioaffinity assay and bioimaging systems and fabricate an electrostatic transferor to calculate and reduce background signal in biological measurement systems. Atomic force microscopy is used independently to calculate binding forces and

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the results of the methods are cross‐correlated. Polystyrenenanoparticle labels and quantum dots of different surface properties and sizes in combination with different antibodies on nanoparticles and solid‐phases are prepared and their effects on nonspecific interactions are investigated in detail. Antibodies and their recombinant fragments are used to elucidate the origin and role of nonospecificity. Thyroid‐stimulating hormone and prostate‐specific antigen are model analytes in the study. Collaboration: University of Turku, TKK

Publications: T. Näreoja, A. Määttänen, J. Peltonen, P. Hänninen, H. Härmä, “Impact of surface defects and denaturation of capture surface proteins on nonspecific binding in immunoassays using antibody‐coated polystyrene nanoparticle labels”, Journal of Immunological Methods, 347, 24‐30 (2009).

Bioactive paper and fibre products (BioAct) Main funding: Finnish Funding Agency for Technology and Innovation (Tekes) Participating FunMat units: LPCC, LPT Piia Gustafsson, Serap Sahin, Pernilla Sund, Carl‐Erik Wilen, Martti Toivakka, Jouko Peltonen Bioactive features may provide new markets and added value products, for example, to pulp and paper, packaging, diagnostic and construction industry. General objective of this proposed project is to develop basic concepts, materials and mass manufacturing methods for producing bioactive paper or fibre based products on large areas. Methods to commercialize potential applications are clarified. Objective is to demonstrate bioactive systems, which detect and/or remove selected molecules (e.g. allergen, toxin), and can be manufactured with mass manufacturing methods on large area. Potential applications include e.g. active and intelligent food casing, anticounterfeiting, printable indicators on magazine or newspaper, construction materials and filters. The contribution by the Laboratory of Polymer Technology to the BioAct project consists of two parts: a) synthesis of a macrocycle library, and b) development of a printable monomer mixture, that gives a hydrogel after UV‐initiatied polymerization. The macrocycle library, which is synthesized on polystyrene beads, is intended for macrocycle‐functionalization of (bio)polymers, to be used primarily for sensors, but also for other applications. The task of the macrocycles is to achieve strong and specific interaction with the analytes. Although combinatorial libraries have been used extensively for drug discovery, few have been developed for other industrial purposes. For industrial applications, the priority is cheap monomers and synthesis, and good chemical stability. Macrocycles are preferred to open chains because the conformational preorganisation in macrocycles gives stronger and more specific association to the target. Macrocycles also have the ability to strike a compromise between structural preorganisation and flexibility to achieve optimal binding. The macrocycle library is synthesized using solid‐phase synthesis (SPS) on polystyrene beads, as a one bead ‐ one compound library using the mix‐and‐split method. The macrocycle is attached to the polystyrene bead using a linker, which will be cleavable for the library, but permanent for the final

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application. The linker attachment point on the macrocycle ('head monomer') also functions as the site for ring‐closure. The rest of the macrocycle consists of an amide oligomer. The chemistry used for ring‐closure is 1,3‐dipolar cycloaddition between a propargyl group and an azide group, the latter attached to the end monomer. For the first attempt at making a macrocycle, a phenacyl linker, and a rather complex head monomer syntheized in solution was used. The completed 14 atom macrocycle was cleaved off with hydrazine, chromatographically purified and characterized by nuclear magnetic resonance (NMR) and mass spectrometry (ESI‐MS). Because of different shortcomings, a new linker and a smaller and more easily synthesized head monomer was also made, and the testing of these is ongoing. Hydrogels. A printable hydrogel must remain liquid in the printing process, and then be cured into a non‐flowing hydrogel afterwards. To achieve this, UV‐polymerizable inks based on acrylic acid monomers have been tested. The swelling of the corresponding hydrogel depends on pH, so that in acidic solution, where the carboxyl groups are un‐ionized, the swelling is low, while in basic solutions with ionized carboxyl groups, the hydrogel will swell. The hydrogels were composed of acrylic acid, a crosslinker, a sensitizer, and a solvent. Several solvents were tested for printability and gel properties. Collaboration: VTT, TKK, University of Lapland, Hansaprint Oy, UPM‐Kymmene Oyj, Tervakoski Oy, Ciba SC Oy, Eagle Filters Oy, Starcke Oy Securities, Oy Medix Biochemica Ab, Orion Diagnostica Oy Publications: P. Gustafsson, S. Grönqvist, M. Smolander, T. Erho, M. Toivakka, and J. Peltonen,” Bioactive pigment coatings comprising enzymes”, Proceedings of 7th International Paper and Coating Chemistry Symposium, Hamilton, Canada, 2009.

Printability on paper and board Main funding: Industry Participating FunMat units: DPC, LPCC Petri Ihalainen, Jouko Peltonen The aim of the project is to carry out versatile surface characterization for paper and board samples. Of special interest have been topographical and thermal properties of polymer films. Publication: P. Ihalainen, K. Backfolk, P. Sirviö and J. Peltonen, “Topographical, Chemical, Thermal and Electrostatical Characterization of a Latex Film Surface as a Function of Annealing Time”, Colloids and Surfaces A, 354, 320‐330 (2010).

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Paper coatings for printed intelligence Main funding: Industry Participating FunMat unit: LPCC Kenneth Nylander, Mikael Ek, Jouko Peltonen Printed electronics is a rapidly developing area of industry. The objective of the project is to apply nano materials as paper coatings for printed electronic applications. Special emphasis is on the structure‐performance relationships and thorough characterization of the novel coatings. Collaboration: Ciba Finland Oy

Development of paper for inkjet printing Main funding: Industry Participating FunMat units: LPCC, DPC Carl‐Mikael Tåg, Jarl B. Rosenholm, Jouko Peltonen Papers available on the market for high speed inkjet printing can roughly be divided into treated grades and high quality specialty paper grades. The treated grades usually perform well in 1‐color printing, printing of barcodes etc., but not so well in 4‐color printing. The very expensive high quality specialty papers perform well in 4‐color printing, but not always so well in printing bar codes. Currently the high quality specialty paper grades are mainly produced on small paper machines, due to limited production possibilities. The aim of the Inkjet paper project is to develop paper grades which perform well in high speed inkjet printing, but with less complex structure and at a lower cost than current specialty inkjet papers. To do this, evaluation of what makes a paper good or bad for high speed inkjet printing will be carried out. Additionally the aim is to decrease the paper waviness which causes problems in the post handling process of the printed product.

Printable array platform for cell studies (PrinCell) Main funding: Finnish Funding Agency for Technology and Innovation (Tekes) Participating FunMat unit: LPCC Helka Juvonen, Tapio Mäkelä, Jouko Peltonen Recent advances in materials science and printing technology offer exciting opportunities to develop completely new types of functional surfaces and patterned device structures. In the field of biotechnology and tissue engineering, cell printing is considered as a very promising and potential

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technique for producing assays and arrays for applications were quick and inexpensive mass production of assays combined with high spatial resolution of deposited active components are needed. In this project we are combining the knowledge from different disciplines to develop technology base for printable advanced cell arrays. The key issue of the proposal is to combine versatile materials research and development with that of advanced printing and coating techniques that enable versatile and inexpensive printing of various biomaterials to complex assays. Essentially, different printing and coating techniques need to be studied because different kinds of materials are involved in preparation of a cell array. The printing technology can be combined and applied into the existing array technology to allow the use of current detection systems. Collaboration: University of Helsinki, Massachusetts Institute of Technology, UPM‐Kymmene, Orion

Pharma, ChipMan

Liquid flame spray nanocoating for flexible roll‐to‐roll web materials (Nanorata) Main funding: Finnish Funding Agency for Technology and Innovation (Tekes) Participating FunMat unit: LPCC Milena Stepien, Jarkko J. Saarinen, Martti Toivakka The project is a collaborative effort to develop a novel nanocoating, liquid flame spray technique for flexible roll‐to‐roll web material such as paper, paperboard or plastic. In this technique, the web‐like material rolls moderately fast through the liquid flame spray or an array of flames. Nanoparticles of size 5‐50 nm generated in the flame are deposited on the surface of the web material creating new properties for the surface. Based on earlier recent work, e.g., surface energy, barrier properties and adhesive properties can be increased. Performance of coatings with coverage in the order of one monolayer of nanoparticles is applicable and has been verified. The project consists of a) a 3 year period of more fundamental studies on selecting the best compounds applicable by this technique to improve the material and, b) a 2 year period to up‐scale the process for a wider web using an array of flames to achieve a smooth and even coating. Collaboration: Tampere University of Technology, Beneq Oy, Kemira Oyj, Stora Enso Oyj, and UPM‐Kymmene Oyj Publications: Milena Stepien, Jarkko J. Saarinen, Hannu Teisala, Mikko Tuominen, Mikko Aromaa, Jurkka Kuusipalo, Jyrki M. Mäkelä, and Martti Toivakka, “Adjustable wettability of paperboard by liquid flame spray nanoparticle deposition”, submitted to Applied Surface Science (2010).

Thermal Effects and Online Sensing (THEOS) Main funding: Finnish Funding Agency for Technology and Innovation (TEKES)

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Participating FunMat unit: LPCC Hanna Koivula, Martti Toivakka The project investigates the influence of temperature distribution on ink‐setting and printability in HSWO printing, determined by experiment, modelling and the (on‐line) measurement of ink‐setting behaviour adopting novel optical devices. Furthermore, an objective is to improve the understanding of heat transfer in pigment coatings in general. The thermal properties of coatings are relevant in several paper manufacturing, converting and printing processes, such as dry coating, calendering and electrophotography. Collaboration: Helsinki University of Technology, Joensuu University, BASF Oy, Omya Oy, M‐Real Oy, UPM‐Kymmene Oyj, MGM Devices Oy, and Finnish Graphic Industry Research Foundation

Novel technology platform for mass produced inexpensive transistors on flexible substrates enabling sensing applications (Flex‐Sens) Main funding: Finnish Funding Agency for Technology and Innovation (Tekes) Participating FunMat units: LPCC, LPT, DP, DPC Anni Määttänen, Dimitar Valtakari, Simon Hermans, Petri Ihalainen, Carl‐Johan Wikman, Carl‐Eric Wilen, Nikolai Kaihovirta, Ronald Österbacka, Jawad Sarfraz, Mika Linden, Jouko Peltonen The main objective of the project is to create a universal technology platform for inexpensive mass produced ion‐modulated transistors which accelerates the development of novel practical device applications. Furthermore, the novel MEM‐FET based transistor technology will be utilized and developed in plastic or fiber based flexible packages, and in technical plastics for switching and sensing purposes. In addition, low‐cost mass produced sensors are developed on flexible substrates for screening of volatile analytes. All electronic detection will be developed via the low‐voltage ion‐modulated transistors that open up completely new possibilities. Collaboration: University of Oulu, Tampere university of technology, University of Turku, Stora Enso, BASF, Perlos, Panipol, Forest Pilot Center, Labmaster

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3.2.5 To understand the electrical, optical and magnetic properties of disordered organic materials

In order to successfully make “intelligent packages”, there is a need to print at basically no cost power sources (i.e. batteries or photovoltaic cells), active components such as transistors and memory cells, as well as INPUT/OUTPUT units, all operating at low‐voltages. This requires a totally new approach to electronics: simple device design and innovative solutions. Traditional organic electronics usually suffers from stability issues and high drive‐voltages; especially for transistors. The use of ions usually offers robust performance at low voltages with less stringent needs for encapsulation, opening up a totally new field in device physics of organic electronics

In order to fully utilize the possibilities that functional materials provide, we need to clarify the electro‐optical and magnetic properties of the functional materials. This allows us to fully utilize the novelty of the materials in printed functionality. We are especially focusing our attention towards the following tasks:

– To understand electro‐optical properties such as charge transport and recombination, magnetic and optical properties of disordered organic materials

– New experimental and numerical modeling tools

– to develop novel solution processable electronic devices for printable active electronics devices, sensors and indicators

The effects of metal impurities in an organic semiconductor on field‐effect transistor properties Main funding: Academy of Finland

Participating FunMat unit: DPh Niklas Björklund, Jan‐Olof Lill, Ronald Österbacka

We have used Particle Induced X‐ray Emission (PIXE) analysis and Particle Induced Gamma‐ray Emission (PIGE) analysis to determine the elemental impurity concentrations in thienol[2,3‐b]thiophene samples that have undergone different washing and extraction procedures to remove impurities. Field‐effect transistors (FETs) were fabricated from the materials and their electrical characteristics show no significant differences between the devices made from different material samples. Reducing the metal residue levels below the one measured in the starting material (300 mg/kg Fe, 7 mg/kg Zn, 3000 mg/kg Pd and 12000 mg/kg Sn) does not improve the FET performance. This suggests that it is not necessary to completely remove metal residues in semiconducting polymers used in FETs.

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1000 100001E-3

0.01

0.1

Mo

bili

ty [

cm2/V

s]

Total impurity concentration [mg/kg]

linear

saturated

13

4

27

56

8

Fig. Typical field effect mobilities for the different materials. The linear mobilities where measured at a constant drain voltage of Vd = ‐5 V and the saturated at Vd = ‐50 V. The error bars show the maximum deviation between the measured mobility values and average mobilities.

Collaboration: Accelerator Laboratory, National PET center, Åbo Akademi University, Laboratory of Analytical Chemistry, Åbo Akademi University and Merck Specialty Chemicals Ltd, Southampton, United Kingdom Publication: N. Björklund, J‐O Lill, J. Rajander, R. Österbacka, S. Tierney, M. Heeney, and M. Coelle, ”The effects of metal impurities in an organic semiconductor on field‐effect transistor properties”, Organic Electronics, 10, 215‐221 (2009).

Simulations of hopping transport in disordered organic materials

Main funding: Academy of Finland, Finnish Funding Agency for Technology and Innovation (TEKES) and

Graduate School of Materials Research

Participating FunMat unit: DPh F. Jansson and R. Österbacka

For hopping transport in disordered materials, the mobility of charge carriers is strongly dependent on

the temperature and the electric field. By numerical simulation we have studied the energy distribution

and the mobility of charge carriers, as a function of electric field, temperature and carrier concentration.

We have shown that both the energy distribution and the mobility can be described by a single

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parameter, the effective temperature, which is dependent on the magnitude of the electric field [1,2].

We have also studied the effects of strong electric fields on hopping conductivity [3]. Monte Carlo

computer simulations show that the analytical theory of Nguyen and Shklovskii , [Solid State Commun.

38, 99 (1981)] provides an accurate description of hopping transport in the limit of very high electric

fields and low concentrations of charge carriers as compared to the concentration of localization sites

and also at the relative concentration of carriers equal to 0.5. At intermediate concentrations of carriers

between 0.1 and 0.5, computer simulations evidence essential deviations from the results of the existing

analytical theories. The theory of Nguyen and Shklovskii also predicts a negative differential hopping

conductivity at high electric fields. Our numerical calculations confirm this prediction qualitatively.

However the field dependence of the drift velocity of charge carriers obtained numerically differs

essentially from the one predicted so far. Analytical theory is further developed so that its agreement

with numerical results is essentially improved.

Fig. Drift velocity as a function of the electric field for different localization lengths. The curves show the theory in the limit of large electric fields. The system size L is 20R. [3]

Collaboration: Phillips‐University Marburg, Germany and 3Institute of Semiconductor Physics and Novosibirsk State University, Russia

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Organic Spintronics

Main funding: Academy of Finland

Participating FunMat unit: DPh

S. Majumdar, H.M. Majumdar and R. Österbacka

Organic spintronics is a part of the research conducted in the Department of Physics, Åbo Akademi University in collaboration with the Magnetism and Superconductivity group of Wihuri Physical Laboratory, University of Turku. We study the basic spin physics of different inorganic and organic materials suitable for spintronic applications and also fabricate spintronic devices and characterize them.

Research related to organic spintronics in this group is mainly two‐fold. On one hand, organic spin valve devices are fabricated using ferromagnetic (FM) La0.7Sr0.3MnO3 (LSMO) and Co as the spin injecting and detecting electrodes and different organic semiconductors (OS) as non magnetic spacers and their properties thoroughly characterized. The best spin valve device, so far, showed more than 80% magnetoresistance (MR) at 5K and detectable room temperature MR response in our devices. Studies are underway to improve this signal for potential applications.

On the other hand, organic diode devices are fabricated and their magneto‐transport properties are studied for understanding the basic physics leading to large MR response of most OS based diodes at room temperature and low magnetic fields (OMAR effect).

Magnetoelectrical measurements were performed on diodes and bulk heterojunction solar cell blends to clarify the role of formation of Coulombically bound electron‐hole (e‐h) pairs on the magnetoresistance (MR) response in organic thin‐film devices. Bulk heterojunction solar cells are suitable model systems because they effectively quench excitons but the probability of forming e‐h pairs in them can be turned over orders of magnitude by the choice of material and solvent in the blend. We have systematically varied the e‐h recombination coefficients, which are directly proportional to the probability for the charge carriers to meet in space, and found that a reduced probability of electrons and holes meeting in space lead to the disappearance of the MR. Our results clearly show that MR is a direct consequence of the e‐h pair formation.

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Fig. %MR as a function of magnetic field (B) in different devices with varying L ratio in a RRP3HT diode (black), in a RRP3HT:PCBM BHSC (red) made from dicholorobenzene and chloroform (blue), and in a MDMO‐PPV:PCBM BHSC (green).

Collaboration: Wihuri Physical Laboratory, University of Turku,Department of Chemistry, University Hasselt, (Prof. vanDerZande), Nanomaterials group at HUT Prof. S. van Dijken. Publications: S. Majumdar, H.S. Majumdar, H. Aarnio, D. Vanderzande, R. Laiho, and R. Österbacka, “The role of electron‐hole pair formation on organic magnetoresistance”, Physical Review B 79, 201202R (2009). S. Majumdar, H. Majumdar, R. Laiho, and R. Österbacka, “Organic spin valves: effect of magnetic impurities on the spin transport properties of polymer spacers”, New Journal of Physics, 11, 013022 (2009). (11pp) S. Majumdar , H. S. Majumdar, H. Aarnio, R. Laiho and R. Österbacka, ”Magnetoresistance Study in Poly (3‐hexyl thiophene) Based Diodes and Bulk Heterojunction Solar Cells”, Phys. Stat. Solidi (a), in press (2009). S. Majumdar, H. S. Majumdar, D. Tobjörk, and R. Österbacka, “Towards printed magnetic sensors based on organic diodes”, Physica Status Solidi: A (2009)

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Study of Half‐metallic manganite La0.67Sr0.33MnO3 (LSMO) thin films made by pulsed laser

deposition for spintronic applications.



S. Majumdar and R. Österbacka

La0.67Sr0.33MnO3 (LSMO), a well‐known half‐metallic manganite has been successfully used as a spin

injecting electrode in many inorganic/organic spintronic devices. Although the Curie temperature (TC) of

bulk LSMO lies well above room temperature, the surface spin polarization start decreasing at a much

lower temperature due to the presence of a large number of paramagnetic clusters at 300K giving much

less SP carriers at the LSMO ‐ barrier interface in spintronic devices. Now, the Double – Exchange (DE)

mechanism in manganites, which controls the charge carrier movement, is significantly modified by

structural defects and substrate induced strains and also on the growth mechanisms. This makes it

necessary to grow the LSMO films on different substrates starting from highly lattice mismatched MgO

(MGO) (~9%) to most closely matched SrTiO3 (STO) (0.87%) and NdGaO3 (NGO) (‐0.2%) to obtain the

best spin injector for our devices. In MGO and STO the strain is compressive while that in NGO is

compressive. So, the growth mechanisms in these three kinds of substrates are very different and thus

we studied the effect of differently strained films, evolution of strain with film thickness and

modification of their spin injection properties. Also using different pulsed laser deposition (PLD)

parameters like temperature and laser repetition rate, the growth and oxygen content of the material is

modified and from the study of their surface morphology, atomic structures, magnetic and transport

properties, we optimized the parameters for achieving maximum SP injection at room temperature.

0 50 100 150 200 250 300 350 400

0.0

0.2

0.4

0.6

0.8

1.0

LSMO/MGO LSMO/STO LSMO/NGO

M /

MS

T (K)

Fig. Magnetization vs. temperature plot of LSMO films on different substrates showing different spin

polarization at room temperature.

Collaboration: Wihuri Physical Laboratory, University of Turku, Finland

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Electrical characterization of organic memories using polarizable nanoparticles

Main funding: Finnish Funding Agency for Technology and Innovation (TEKES) and Academy of Finland


J. K Baral, H. S. Majumdar and R. Österbacka

We demonstrate a memory device in which the fullerene‐derivative [6,6]‐phenyl‐C61 butyric acid methyl ester (PCBM) as well as metallic nanoparticles mixed with inert polystyrene (PS) matrix is sandwiched between two aluminum (Al) electrodes. Above a threshold voltage of <3V, independent of thickness, a consistent negative differential resistance (NDR) is observed in the devices of thickness range from 200nm to 350nm made from solutions with 4 wt% to 10 wt% of PCBM in PS. We found that the threshold voltage (Vth) for switching from high impedance state to low impedance state, the voltage at maximum current density (Vmax) and the voltage at minimum current density (Vmin) in the NDR regime are constant within this thickness range. The current density ratio at Vmax and Vmin is more than or equal to 10, increasing with thickness. Furthermore, the current density is exponentially dependent on the average hopping distance longest tunneling jump between two PCBM molecules, suggesting a multiple tunneling mechanism between individual PCBM molecules. This is further supported with temperature independent NDR down to 240K.

Fig. a) Absolute current density as a function of voltage for pure polystyrene (PS, d = 200 nm) and 2‐6 wt% PCBM/PS compositions (d = 250 − 260 nm). (b) Current density as a function of voltage for 10‐40 wt% PCBM/PS compositions (d = 250 nm), showing ohmic behavior. (c) Strength of the electric field in the vicinity of two dielectric spheres where an initially uniform electric field (E0) is applied. (d) Combination of a TEM micrograph and a schematic illustration showing the polarisation between the PCBM clusters, separated by the PS matrix. All devices were annealed at 120°C. [2]

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Collaboration: Department of Engineering Physics and Mathematics, and Center for New Materials, Helsinki University of Technology, FINLAND and VTT Printed Electronics Center, Finland

X‐ray photoelectron spectroscopy study on polymer/fullerene nanocomposites



Daniel Tobjörk, Jayanta Baral, Himadri Majumda and Ronald Österbacka

We studied the chemical composition of memory devices as a function of depth by using X‐ray

Photoelectron Spectroscopy (XPS) and sputtering with argon ions. The depth profile in the figure below

shows the slightly oxidized aluminum top electrode, the carbon rich active material consisting of a

mixture of polystyrene (PS) and [6,6]‐phenyl‐C61 butyric acid methyl ester (PCBM), the bottom aluminum

contact and finally the glass substrate (containing silicon and oxygen).

2 4 6 8 10 12 14 16 18 20 22 24 26 280

10

20

30

40

50

60

70

80

90

100

Sputter time (min)

Ato

mic

con

cent

ratio

n (%

)

Al2p C1s O1s Si2p

Fig. The composition of an Al/PS:PCBM/Al memory device is shown as a function of sputtering time in this depth profile. The atomic concentrations were determined from the area of the carbon (C1s), oxygen (O1s), aluminum (Al2p) and silicon (Si2p) peaks in the XPS spectrum. The broader shape of the bottom electrode was explained by the inhomogeneous sputtering process.

From the results we could conclude that the thermal evaporation of the aluminum electrodes had not

led to any observable inclusion of aluminum (<0,1‐1 at.%.) into the active material layer. Furthermore,

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the observation of alumina on the bottom contact gave some clues to the understanding of the device

operation principle. We also compared the XPS results with Transmission Electron Microscopy (TEM)

images of cross sections of the memory devices.

Collaboration: Department of Engineering Physics and Mathematics, and Center for New Materials, Helsinki University of Technology, FINLAND

Charge Transport and Recombination in hybrid organic‐TiO2 based devices

Main funding: Academy of Finland Participating FunMat unit: DPh, DPC

S. Sandén, G. Sliauzys, Q. Xu, J‐H. Smått, M. Lindén and R. Österbacka The purpose of this project is to clarify the charge transport in hybrid organic–inorganic solar cells. The main materials studied are TiO2, poly(3‐hexylthiophene) (P3HT) and the fullerene derivative PCBM. By using nanostructured TiO2 that has pores through which the underlying substrate can be reached, we have the possibility to utilize this in the manufacturing of a novel intrinsic tandem solar cell. To clarify the charge transport and recombination in these devices, we are using time of flight (ToF), charge extraction by linearly increasing voltage (CELIV) and double injection (DoI) techniques. The use of these different techniques makes it possible to obtain quantities such as mobility, lifetime etc. which enable us to characterize the charge transport and recombination in these devices. We have measured charge transport and recombination of TiO2:P3HT films, where the TiO2 films have been flat, porous or nanostructured. By measuring on these different surfaces it is possible to separate the effect of the interface between TiO2 and P3HT. It has been concluded that the interface gives rise to a large amount of surface traps which affects the charge transport in these devices. Collaboration: Department of Solid State Electronics, Vilnius University, Vilnius, Lithuania Department of Chemistry, University of Joensuu (Prof. T. Pakkanen) and Biomaterials center Univ. of Turku (Dr. S. Areva)

Charge transport and recombination in bulk‐heterojunction solar‐cells

Main funding: Academy of Finland Participating FunMat unit: DPh

G. Sliauzys and R. Österbacka

One of the main factors limiting the conversion efficiency in organic solar cells is the recombination of

the charge carriers. In low mobility materials a bimolecular Langevintype recombination is usually

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observed [1]. Langevin recombination is caused by the probability for electrons and holes to meet in

coordinate space, and therefore depends on the transport properties of the charge carriers.

We have previously shown that in bulk heterojunction solar cells made from blends of regioregular

poly(3‐hexylthiophene) with [6,6]‐phenyl‐C61‐butyric acid methyl ester (RRP3HT:PCBM) the bimolecular

recombination is reduced by 1000 times with respect to the Langevin recombination [1]. Using different

experimental methods such as double injection current transients (DoI), integral mode time‐of‐flight

(TOF), and charge carrier extraction with linearly increasing voltage (CELIV)we found that the

bimolecular recombination coefficient depends on density of the charge carriers n. This dependence is observed only in samples, where lamellar structures are formed [1].

In this work, we shown that recombination in regioregular poly(3‐hexylthiophene):[6,6]‐phenyl‐C61‐

butyric acid methyl ester (RRP3HT:PCBM) bulk heterojunction solar cells is caused by two dimensional

(2D) Langevin recombination in the lamellar structures of RRP3HT, which are formed in the annealing

process [2]. Due to the 2D Langevin process, the bimolecular recombination coefficient is reduced in

comparison to the 3D case, and also depends on the density of charge carriers.

Collaboration: Department of Solid State Electronics, Vilnius University, Lithuania, Linz Institute for Organic Solar Cells, Johannes Kepler University, Linz, Austria and Konarka Austria, Linz, Austria

Publication: G. Juska, G. Sliauzys, K. Genevicius, Nerijus Nekrasas, K. Arlauskas, and R. Österbacka, ”Two‐Dimensional Langevin Recombination”, Applied Physics Letters, in press (2009)

Photoexcitation dynamics in disordered organic materials

Main funding: Academy of Finland Participating FunMat unit: DPh

Harri Aarnio, Mathias Nyman, Ronald Österbacka

Optical properties of an electroluminescent poly(phenylene vinylene‐cofluorenylene vinylene) (BPPPV‐

PF)‐based _‐conjugated polymer using absorption, photoluminescence (PL), time‐resolved photo‐

luminescence (TRPL), continuous wave (CW) and transient‐photoinduced absorption (PA) spectroscopic

techniques.

Transient photoinduced absorption measurements have been performed on the alternating

polyfluorene copolymer, poly[2,7‐(9,9‐dioctylfluorene)‐alt‐5,5‐(4’,7’‐di‐2‐thienyl‐2’,1’,3‐benzothia‐

diazole)] (APFO3) on femtosecond to nanosecond timescales. Further, delayed fluorescence has been

measured up to microsecond timescales. Based on these results we have created a model of the

photoexcitation dynamics in the polymer. The model includes decay of singlet excitons and intrachain

polaron pairs, but also build‐up and decay of interchain polaron pairs. The results are modeled

numerically and the parameters which govern the generation and recombination processes are

extracted.

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Collaboration: Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), Singapore and Lund Laser Center (Prof. V. Sundström)

A Combined Optical and Electrical Method for Measuring Charge Carrier Dynamics in Bulk‐

heterojunction Solar Cells

Main funding: Academy of Finland (Morphoso)) Participating FunMat unit: DPh

M. Nyman, H. Aarnio and R. Österbacka

A novel method for measuring charge carrier dynamics in bulk‐heterojunction solar cells has been

developed. The method combines transient photo‐induced absorption (tPA) with charge extraction by a

pulsed voltage (CEPV). The transient photo‐induced absorption technique is used to optically study the

decay rates of excitations on ns – µs timescales. Some of the charges are extracted by a voltage pulse

and the subsequent alteration of the excitation decay rates is studied. The amount of extracted charges

is measured and compared to the decrease in the photo‐induced absorption.

The method has been tested on bulk heterojunction solar cells based on the conjugated polymer poly(3‐

hexylthiophene‐2,5‐diyl) (P3HT) and the fullerene derivative [6,6]‐phenyl‐C61‐butyric acid methyl ester

(PCBM).

Collaboration: Department of Solid State Electronics, Vilnius University, Lithuania, Bioorganic

electronics, Linköping University, and Fraunhofer ISE.

Ion‐conducting membrane based organic transistors

Main funding: Åbo Akademi University and The Foundation of Åbo Akademi University Participating FunMat unit: DPh, LPT

Nikolai J. Kaihovirta, Carl‐Johan Wikman, Tapio Mäkelä, Carl‐Eric Wilén, and Ronald Österbacka

We have developed a novel concept of organic transistors that uses ion‐conducting membranes as gate

insulators. The fabrication steps of the membrane‐FET (MemFET) can be shown to be fully implemented

into a large‐area fabrication line. The thickness of the used membranes varies between 50 and 150 mm.

Therefore, they may be used as mechanical support, removing (at least) one process step. The idea of

using an insulator both as gate dielectric and support has been presented before. In our case, however,

the very thick membrane provides mechanical robustness, allowing at the same time low‐voltage

operation with a high current output. We show that both a commercially available membrane and

membranes optimized for different ionic species can be used for MemFETs. The membrane can be

patterned to be locally ion conducting for MemFETs as well as for other purposes where a solid

electrolyte is required. This concept also allows for multifunctional integration of organic devices on the

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selfsupported membrane, as illustrated in the last section where an electrochromic (EC) display pixel is

connected to a MemFET that is integrated on the same membrane. Hence, the versatile properties of

the membrane are successfully utilized.

Fig. a) Schematic cross‐section of the MemFET. The membrane acts both as gate insulator and mechanical support. b) Output and c) transfer curves of a Nafion115 MemFET measured in inert atmosphere. d) Chronoamperometric response of a Nafion115 MemFET when switching between off and on states. The drain‐voltage is kept constant.

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3.2.6 Printable active electronic Sensors, Indicators and Devices

When functional inks are used in applications, different printing and coating techniques are needed. To

realize low‐cost roll‐to‐roll production of intelligent paper‐ and plastic based products, there is a need

for high‐speed production techniques. The target for the Functional Printing Laboratory (FPL) is to

demonstrate suitable roll‐to‐roll printing techniques for functional materials within FUNMAT as well as

to develop novel methods for functional inks including e.g. insulating, semiconducting, conducting or

magnetically responsive materials.

The FPL hosts laboratory scale, versatile functional printing equipment for our partners. We have

currently used reverse gravure coating (RG) and inkjet printing techniques to demonstrate printed

organic electronic devices on both plastic and fibre‐based substrates. Due to the different nature of the

functional inks one printing method cannot cover all the needs. Different solvents, viscosities, surface

tensions or particle sizes play a large role for the print quality. Also the device configurations, alignment

accuracy and minimum feature sizes are parameters which play a crucial role when choosing the most

suitable printing process.

We are also developing a novel continuous roll‐to‐roll manufacturing technique for testing and

prototyping purposes. In our modular roll‐to‐roll table‐top printer (FUNPRINTER) at least five different

printing units (gravure, flexo, coating, ink‐jet, lamination) can be used sequentially. We can analyze the

printing parameters in‐situ since speed of the web can be controlled from 0.1 meters/minute up to 20

meters/minute. This small scale roll‐to‐roll device enables us to demonstrate fully printed applications

already when only a few milliliters of functional inks are available and when the material of choice is not

commercially available.

Surface energy patterning for inkjet printing in device fabrication

Main funding: Finnish Funding Agency for Technology and Innovation (TEKES) Participating FunMat unit: DPh, DPC

Jian Lin, Per Dahlsten, Mika. Linden and Ronald Österbacka

For application of device fabrication by inkjet printing, an accurate and high resolution patterning

method is required. However, the printing resolution depends on the minimum size of inkjet nozzle,

which is limited by the surface tension of the inks. And the quality of the inkjet printing also needs

improvement because of wrong and satellite droplets. An expanded control of ink deposit in inkjet

printing with substrate modifications can be used to improve the resolution of the devices. Our strategy

is depositing a hydrophobic pattern on a hydrophilic substrate firstly, and thereafter prints the

functional ink on top of the pattern with hydrophilic lines of suitable width. Higher resolution and better

77

ink‐substrate combination can be obtained by this method. This visible and easy processing pattern can

be used widely for more precise, thin and sharp lines, and smaller devices.

Fig. Schematic outline of the procedure for PI surface energy pattern by microcontact printing and inkjet printing on patterned PI.

Fig. Comparison of ink printed on a piece of patterned PI between areas with ODTS layer (right) and without ODTS layer (left side). The ink was printed as a matrix with 20 m dot spacing.

Collaboration: Department of Electronics, Tampere University of Technology, Tampere, Finland, Vicinics consortium at Tampere University of Technology, plus industry.

78

Printable Electronics based Sensor Platform Main funding: Finnish Funding Agency for Technology and Innovation (TEKES) Participating FunMat unit: DPh

Niklas Björklund, Fredrik Pettersson, Himadri Majumdar and Ronald Österbacka The main objective of this project is to develop printable electronics towards a technology platform suitable for development of embedded large area sensor applications. This goal can be split following objectives.

- combination of different printing process with various other (e.g. laser, electrical sintering, etching) processing technologies in high volume processes

- producing printed platforms suitable for antenna, organic transistor, sensor and silicon IC integration

- development of novel low voltage switching transistors for printed sensor multiplexing using combinational processes

The main responsibility for the group at DPh is to develop solutions for R2R‐compatible low‐voltage organic field‐effect transistors (OFETs). Reducing the capacitive coupling is the key to low‐voltage operation (below 5 V); the efforts have therefore been concentrated to the dielectric layer. Several organic dielectrics and inorganic oxides have been studied, Al2O3 have so far proven to be the most promising approach.

Fig. Schematic layout of the low‐voltage Al2O3 OFET.

Fig. Typical transfer and output (inset) characteristics for the low‐voltage Al2O3 OFET.

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Fig. 2. A schematic image of the roll‐to‐

roll reverse gravure coating process.

Fig. 3. A schematic image of the architecture

of the reverse gravure coated organic bulk

heterojunction solar cell.

Collaboration: Department of Electronics Oulu University, Department of Electronics, Tampere

University of Technology, plus industrial partners.

Roll‐to‐roll fabrication of plastic solar cells

Main funding: Participating FunMat unit: DPh

Daniel Tobjörk, Harri Aarnio, Tapio Mäkelä and Ronald Österbacka

Plastic solar cells can be fabricated from solution

processable materials on flexible substrates. This is a great

advantage compared to silicon based solar cells, since this

offers the possibility of using similar low‐cost large‐area

roll‐to‐roll fabrication methods as are used in the printing

industry. In this work we have studied the reverse gravure

coating technique (see Fig. 2) as a way of producing thin

homogeneous films for plastic solar cells. [1,2]

A schematic image of an organic bulk

heterojunction type solar cell is shown in Fig. 3. The

bottom poly(3,4‐ethylenedioxy‐thiophene):poly

(styrene sulfonate) (PEDOT:PSS) layer is a hole

conducting polymer, while the active layer is based on

the conjugated polymer regioregular poly(3‐

hexylthiophene‐2,5‐diyl) (P3HT) and the fullerene

derivative [6,6]‐phenyl‐C61‐butyric acid methyl ester

(PCBM).

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Fig. An image of flexible HIFETs.

Fig. 4. J‐V curves of a reverse gravure

coated and a spin coated plastic solar

cell under simulated AM1.5 illumination

(100 mW/cm2).

The hole conducting PEDOT:PSS layer and the 100 nm thick

active organic P3HT:PCBM layer were subsequently reverse

gravure coated on an indium tin‐oxide (ITO) covered

polyester (PET) film in ambient air. Working solar cells were

achieved after annealing and thermal evaporation of the

top contact (LiF and Al). The current‐voltage (J‐V)

characteristics of the reverse gravure coated solar cell was

measured under simulated AM1.5 illumination and

compared with a reference solar cell that was fabricated by

laboratory scale spin coating methods on a glass substrate

in a nitrogen glove box (see Fig. 4). The power conversion

efficiency (PCE) of the reverse gravure coated organic solar

cells was determined to around 0.8% and was very close to

the reference device.

All‐printed low‐voltage transistors on plastic substrate Participating FunMat unit: DPh

Daniel Tobjörk, Nikolai Kaihovirta, Tapio Mäkelä and Ronald Österbacka

Conducting, semiconducting and insulating materials in

solutions and dispersions provide the possibility of fabricating

organic devices on flexible substrates with similar techniques

as are used in the printing industry. [1‐3]

We have manufactured organic transistors on low‐cost

flexible substrates completely with fabrication techniques

that allow a high throughput of devices at a low cost. All‐

printed hygroscopic insulator field effect transistors (HIFETs)

were demonstrated by ink‐jet printing all electrodes (from

conducting polymer and silver nanoparticle inks) and applying

the polymer semiconductor and insulator layers from

solutions with the roll‐to‐roll reverse gravure coating

technique in ambient air. [1,2]

On problem with most organic transistors is the usually very high driving voltage (10‐100V), which is not

suitable for portable electronics. However, the printed HIFETs operate at low‐voltage in ambient

(humid) air, thanks to the ionic drift in the polymer insulator, poly(4‐vinylphenol) (PVP).

We have also investiged the effect of the substrate roughness on the HIFETs and compared this with

traditional organic FETs (OFETs). In Fig. 2. a comparison of devices fabricated on two different polyester

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substrates is shown. The root‐mean‐square (RMS) roughness of the PET‐505 substrate was measured to

4‐6 nm (by AFM on 20 μm ×20 μm areas) while the same value on the rougher low‐cost Mylar® A

substrate was 25–50 nm.

In opposite to the traditional OFETs the HIFETs were found to be rather insensitive to the roughness of

the plastic substrates. Also the yield of working devices was found to be much higher with the HIFETs.

This insensitivity to the surface roughness is due to the thick insulator layer (1‐2 µm) in combination

with the ion modulation which also makes the transistor insensitive to variations in the insulator

thickness. [2]

Fig. AFM images of (a) PET 505 and (b) Mylar® A substrates. Typical transfer curves for (c) HIFETs and (d)

OFETs on PET 505 and Mylar®. The square root of the drain currents are shown for the same (e) HIFETs

and (f) OFETs. [2]

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Printed low‐voltage organic transistors on paper

Main funding: Participating FunMat unit: DPh, LPCC

Daniel Tobjörk, Nikolai Kaihovirta, Roger Bollström, Anni Määttänen, Tapio Mäkelä, Petri Ihalainen,

Jouko Peltonen, Martti Toivakka and Ronald Österbacka

Inspired by the robustness and printability of the hygroscopic

insulator organic transistors (HIFETs) on the rough plastic substrate

we were able to manufacture these transistors even on paper

substrates. [1] The recyclable paper based substrates were specially

developed for this purpose. The ink‐jet printed silver nanoparticle

elelctrodes were made conductive within 10 seconds by exposing

them to an infrared lamp. Ink‐jet printing was also investigated as a

way of applying the semiconductor and insulator layers. The output

curve of a “paper transistor“ that has been stored in ambient air for

4.5 months is shown in Fig. 1.

Publications: R. Bollström, A. Määttänen, D. Tobjörk, P. Ihalainen, N. Kaihovirta, R. Österbacka, J. Peltonen and M. Toivakka, “A multilayer coated fiber‐based substrate suitable for printed functionality”, Organic Electronics (2009), doi:10.1016/j.orgel.2009.04.014

Ink‐jet printed organic diodes as magnetic sensors

Main funding: Åbo Akademi University and the Foundation of Åbo Akademi University Participating FunMat unit: DPh

Daniel Tobjörk, Himadri S. Majumdar, Sayani Majumdar, and Ronald Österbacka

Diodes are important basic components in electronic circuits as rectifiers. By using suitable materials

and architecture diodes are also used in the special areas of solar cells and light emitting diodes.

Another interesting application of using organic diodes as magnetic sensors was opened up by the

discovery of the organic magnetoresistance (MR) effect.

We have studied ink‐jet printing as a way of manufacturing organic diodes and using them as

magnetic sensors. The printed diodes were fabricated on flexible plastic substrates with pre‐

patterned aluminum contacts. Both the polymer semiconductor and the top silver electrode were

applied by ink‐jet printing. The silver nanoparticle ink was annealed on a hot plate at 120⁰C for

20 min before measuring the diodes. The printed devices showed a positive MR response of 10 –

Fig. Output curve of a HIFET

measured 4.5 months after

the fabrication.

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15%, which was almost as good as for spin coated and evaporated devices. The device yield and

stability of the printed devices was, however, not yet as good as for the laboratory scale fabricated

devices.

Publications: S. Majumdar, H. S. Majumdar, D. Tobjörk, and R. Österbacka, “Towards printed magnetic sensors based on organic diodes”, Physica Status Solidi: A (2009), Accepted. arXiv:0809.3864v1

Adjustable packaging line of the future

Main funding: EAKR, Development programs. Participating FunMat unit: DPh The packaging business is considered to have significant growth potential in the near future. At present, fiber‐based packaging materials are considered to have great potential in terms of packaging technologies, and to provide opportunities that should be seized as soon as possible. The “Adjustable packaging line of the future” projects are to develop and construct a new type of flexible manufacturing system platform for the manufacturing of paperboard packages. The project concentrates on improving the conventional production process of paperboard packaging manufactured by pressing so that it is a competitive alternative to other packaging solutions – mainly plastic and aluminum ones. The packaging market is growing rapidly in the industrialized world as families become smaller, and in the developing world due to the strong growth of the middle class. The turnover of the global packaging market is approximately 500 million dollars a year, which is six times the amount of Finnish exports annually. Forecasts indicate that the packaging market will continue to expand in the coming years. The need for manufacturing system improvement is evident because food products companies have turned to Finnish paperboard producers in search of ecological packaging solutions. Manufacturers of packaging materials do not, however, have sufficient expertise to develop the manufacturing processes of packages. Therefore, exploring the possibilities to use paperboard in future innovative packaging solutions requires in‐depth academic research.

The “Adjustable packaging line of the future” projects are a collaborative effort of the Lappeenranta

University of Technology LUT Packaging Research Institute, the Åbo Akademi University Centre for

Functional Materials, and the Lahti University of Applied Sciences Institute of Design. It responds to the

needs of Finnish packaging research, the forest industry and paperboard converting companies by

building a cross‐regional network composed of experts in material and manufacturing technologies and

design from Southern Finland. The main aim of the project is to develop and construct the adjustable

and modular packaging line. When the adjustable packaging line is finished, it will be a key element and

research platform in the research and education involving packaging technologies at Lappeenranta

University of Technology.

The overall budget of the “Adjustable packaging line of the future” projects is approximately 2.1 million

Euros, of which the ERDF covers 1.4 million Euros. The head of research responsible for the projects is

Juha Varis, Professor of Production Engineering at Lappeenranta University of Technology, accompanied

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by Project Manager Mika Kainusalmi. Professor Ronald Österbacka is in charge of the Åbo Akademi

University sub‐project on electronic indicators, and Senior Lecturer Marja Lampainen is responsible for

the sub‐project of the Lahti Institute of Design focusing on packaging design and the industrial design of

the packaging line.

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3.2.7 Functional Materials Printing (FunPrint) Center

Project leader PhD Tapio Mäkelä

Main funding: Åbo Akademi Foundation

Participating FunMat units: DPC, LPT, LPC, LPCC, DPh

INTRODUCTION

A huge interest in low cost and high speed manufacturing methods for printed intelligence has surged and in recent years the first printed prototypes have been launched world wide. To realize low‐cost roll‐to‐roll production of intelligent paper‐ and plastic based products, there is a need for high‐speed production techniques, but especially materials development and formulation is critical for the successful printing of the needed multilayered structures. Typically, the problem lies in up‐scaling of the processing.

When functional, responsive materials are used as inks in applications, various printing and coating techniques are required. The sometimes incompatible characteristics, such as solubility, viscosity etc. of the individual functional materials requires different printing methods to avoid problems in multilayer printing caused by wettability and solvation for instance. The device configurations, alignment accuracy and minimum feature sizes are parameters which play a crucial role when choosing the most suitable printing process. The target for the Functional Material Printing Center (FUNPRINT) is to demonstrate suitable roll‐to‐roll printing techniques for functional materials and devices produced within FUNMAT.

The FUNPRINT hosts versatile, laboratory scale functional printing equipment for our partners. We have demonstrated fully printed organic electronic devices on both plastic and fibre‐based substrates. We have used hot embossing/imprinting technique to manufacturing plastic devices for bio applications. As a final target in FUNPRINT we will prototype an all printed device where several functionalities will be combined in the same process.

BACKGROUND

As the basis of FUNPRINT, a novel continuous roll‐to‐roll manufacturing device for testing and prototyping purposes were developed. In our modular roll‐to‐roll printer (FUNPRINTER) more than five different printing units (e.g. gravure, flexo, reverse gravure coating, ink‐jets, and hot embossing or lamination) can be used sequentially. We can analyze the printing parameters in‐situ since speed of the web can be controlled from 0.1 meters/minute up to 20 meters/minute. This small scale roll‐to‐roll device enables us to demonstrate fully printed applications already when only a few millilitres of functional inks are available. This demonstration machine is the link between research work and a high volume industrial manufacturing.

Some of the proposed applications do not need a continuous manufacturing process and sometimes those are easier to demonstrate without continuous web. The first printing equipment: Inkjet (A3‐sheet) system were purchased and installed in year 2006 as well as sheet resistivity measuring unit which is used for fast analyzing on conductivity from a printed web. Reverse Gravure (roll‐to‐roll) coater were installed in year 2006 and simultaneously, the design and manufacturing of the multifunctional roll‐to‐roll printer (FUNPRINTER) started.

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Furthermore, FUNPRINT has played a crucial role in demonstrating the printed devices such as nanoparticulate magnetic inks, organic field effect transistors, organic solar cells and optimized paper surfaces. These results have been reported more detail elsewhere in this report.

TARGETS

Within FunMat, it is very important to understand the chemical and physical behavior of materials, surfaces and the printing process itself. The demonstration of the printability of high volume applications such as electronic devices, functional surfaces and different indicators are the main targets of the FUNPRINT research.

For cheap, large‐scale manufacturing, roll‐to‐roll printing techniques are natural choices. Conventional roll‐to‐roll techniques such as gravure, flexographic printing and inkjet‐printing as well as coating methods such as reverse gravure, blade coating and lamination will be used in our equipment. However, other techniques such as offset, spray coating or other novel printing methods can be added later when needed.

LABORATORY AND EQUIPMENT

The FUNPRINT laboratory consists of 50 m2 room including 3 fume chambers where the laboratory scales Inkjet‐printer and a reverse gravure coater has been installed. Hot embossing and resistivity measurement units are installed on laboratory table. Furthermore, the novel roll‐roll FUNPRINTER has been ready to use in the beginning of 2008. During 2009 master‐ and doctoral students have received training for using these special laboratory equipments. In the following chapters the most important laboratory equipment were shown more detailed and results in the year 2009 observed. The FUNPRINT laboratory was fully funded by Åbo Akademi University with the funds provided by the Åbo Akademi Foundation via the strong research environment program.

INKJET

Inkjet is one very important part of our research, both from a manufacturing point of view as well as for materials testing. Dimatix Material Printer DMP‐2800 was installed in fume chamber and it is capable of printing A3 size substrates (Fig.1). Results from successful ink‐jetted results in 2009 are reported in the references [3‐4 and refs. therein]. Furthermore, roll‐to‐roll suitable Inkjet from Imaje is used in FUNPRINTER for continuous all‐printed devices.

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Fig. 1. Dimatix material printer (A3 size) and printed Inkjet printed Ag‐ source‐drain structures on plastic substrate.

REVERSE GRAVURE COATING

The principle of reverse gravure coating method is shown in Fig. 2. In the reverse gravure method, the patterned roll (e.g. gravure roll) rotates in the opposite direction to the web and “kisses” the coated surface without a backing roll. Otherwise this methods is very similar than gravure method. The small contact area between the transfer roll and web enables a good thickness control from ca 10 nm to several micrometers. The coating speed can be varied from 0.1 up to ca. 2 m/minute. In the machine (from Yasui Seiki) shown in Fig. 2 the web width is 10 cm. The reverse gravure method is used in industry to coat thin liquid films (1‐50 mm) when ink viscosities are between 1 and 2000 mPas. The dry thickness of the layer can be varied by changing the ink‐concentration, coating roll, roll speed or web speed.

Fig. 2. Reverse gravure device from Yasui Seiki and an example of a roll of coated inherently conducting polyaniline on polyethylene tereftalate (PET).

www.dimatix.com

www.dimatix.com

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As an example of using unique combination to producing OFET structure were reported e.g. in Ref. 3. In this example inkjetting and reverse gravure coating were used to demonstrate OFET device. Process flow chart and device were shown in Figure 3.

Figure 3. An example of process for producing OFET where different roll‐to‐roll suitable printing methods (inkjet and reverse gravure) have been used [3].

FLEXOGRAPHIC PRINTING

In the flexible image plate the image element is raised above the non‐image area. In the FLEXO process the printing ink is first transferred to the so‐called anilox roll and the surplus is removed by blading (doctor blade). The ink is transferred from the anilox to the flexoplate, which contains the desired pattern. The flexoplate transfers the image to the web. A schematic picture of FLEXO is shown in Figure 4. The anilox roll is ceramic or chromium coated containing cells with widths corresponding to 200‐600 lines/cm. The flexible printing plate is made of photocurable rubber and the typical resolution in the photopolymer plate is approximately 60 lines/cm (50‐100 micrometer). The printing ink transfers from the flexoplate to the web using only light pressure.

Fig. 4. Schematic presentation of flexographic (FLEXO) printing (left) and 20 meter of printed Ag source drain structures on paper substrate (right). Structures are printed using FUNPRINTER device.

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HOT EMBOSSING

A hot embossing and small scale embossing unit was installed in the FUNPRINT laboratory in 2008. In Fig. 4 the basic principle of the planar and roll‐to‐roll hot embossing methods are shown. A metal stamp is heated above the glass transition temperature of a polymer and pressed against the polymer. The pressure is kept constant while the metal stamp is cooled close to the room temperature. After this, the stamp is released and the stamp feature is transferred to the polymer. In the end of 2009 the roll‐to‐roll embossing unit was used in FUNPRINTER. In the roll‐to‐roll embossing method flexible Ni‐stamp is used instead of planar stamp. In this case Ni‐stamp is wrapped on metal cylinder and heated by using IR heater element. These results will be reported in 2010.

Fig. 4. Schematic presentation of hot embossing techniques is shown. The heated metal stamp is pressed against the polymer layer at temperature above the glass temperature of the polymer, after which the stamp is cooled and released.

Figure 5 shows a metal stamp used in the planar hot embossing experiments and an example of the printed well‐structure on the 1 mm thick polycarbonate film. The used temperature is 140 C, pressure ca, 8 MPa and embossing time 5 min. The printed structures will be used in the bio applications in the future. The roll‐to‐roll hot embossing mold is shown in figure 5 (left).

Metal stamp

T > Tg, P

Polymer

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Fig. 5. A graved Al‐stamp used in the experiments (left). The stamp consist 15 well structures with a diameter of 1 mm and height of 2 mm. The printed example in polycarbonate film is shown in (center) and flexible Ni‐mold used in roll‐to‐roll hot embossing (right).

FUNPRINTER‐DEVICE

This multifunctional and modular printing device was designed to include reverse‐gravure, gravure, flexographic, lamination/calendaring and Inkjet units. The web width was adjusted to 10 cm to keep material consumption as low as possible. The printing speed can be varied from 0.1 m/minute up to ca. 20 m/minute. All printing units are placed in sequence which allows the use of different printing techniques in one printing cycle as well as interchanging of printing sequence. All units are synchronized. In the year 2009, roll‐to‐roll hot embossing equipment was manufactured particularly for the use in bio applications. The real FUNRINTER device is shown in Fig. 6.

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Fig. 6. The unique roll‐to‐roll printing device (Funprinter) is shown. The speed control and inkjets are operated by a computer when pressures and temperatures are controlled manually. The order of the printing units can be changed easily for versatile printing with low material consumption.

In the year 2009 FUNPRINTER were further developed by adding three flexographic units and roll‐to‐roll reverse gravure coating unit together. Also two inkjet units can be used at the same time. The alignment of the two inkjet units is software controlled. The inkjet heads are shown in Fig. 7 where oil based inks are used for demonstrating the alignment of the two heads. In the year 2009 an optical camera system is being installed. An aligning accuracy of ca. 100 micrometer is needed.

Fig. 7. The inkjet heads on the roll‐to‐roll printing device (Funprinter). First head contain 128 nozzles (left) and second head 512 nozzles (right). Aligning of inkjet units is performed by using inkjet controlling

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software and delay time therein. The roll‐to‐roll inkjet is tested by printing Carbon based ink on paper substrate.

As an example of using multiple printing units at the same time a thermocromic device (“hidden code”) is printed. Schematic principle of the printing process is shown in Fig. 8 where Inkjet 1 is used to print first layer, reverse gravure method second and inkjet 2 third layers. In the device the hidden code appears when device were heated above transition temperature (47 C). Thermochromic ink turns from red to transparent and also the code under the thermochromic layer becomes visual (Fig.9).

Fig. 8. A schematic image of the continuous roll‐to‐roll manufacturing process is shown. Three different steps are used in device manufacturing: hidden code is printed on web using inkjet (Inkjet 1); web is coated with thermochromic ink using reverse gravure (RG) coating technique and finally visual layout using inkjet (Inkjet 2). The inks used in the experiment were dried right after the printing unit (dryers 1‐3) and therefore layering was possible.

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Fig. 9. A schematic image of the thermochromic device is shown (right). In the device the hidden code appears when device were heated above transition temperature (47 C) (left). Thermochromic ink turns from red to transparent and also the code under the thermochromic layer becomes visually readable.

Collaboration: Future Printing Center, Hansaprint, UPM, StoraEnso, PANIPOL, TTY, VTT, DTU, LUND Publications: (FUNPRINT related publications 2009) Kaihovirta, Nikolai; Wikman Carl‐Johan; Mäkelä, Tapio; Wilén, Carl‐Erik; Österbacka, Ronald; Self‐Supported Ion‐Conductive Membrane‐Based Transistors, Advanced Materials 29 (24) (2009) 2520‐2523. Kaihovirta, Nikolai; Wikman, Carl‐Johan; Mäkelä, Tapio; Wilén, Carl‐Eric; Österbacka, Ronald; Low‐voltage self‐supported organic transistors based on ion‐conductive membranes, Proceedings of the XLIII Annual Conference of the Finnish Physical Society. Espoo, Finland, 12 ‐ 14 March 2009. Helsinki University of Technology, Espoo (2009), 264. Tobjörk, Daniel; Kaihovirta, Nikolai; Mäkelä, Tapio; Österbacka, Ronald; All‐printed low‐voltage organic transistor on a low‐cost plastic substrate, Proceedings of the XLIII Annual Conference of the Finnish Physical Society. Espoo, Finland, 12 ‐ 14 March 2009. Helsinki University of Technology, Espoo (2009), 282. Lin, Jian; Pekkanen, J; Mäntysalo; Matti; Mäkelä, Tapio; Österbacka, Ronald; Utilization of selective patterning for inkjet printing in the electronics manufacturing, IMAPS Advanced Technology Workshop and Tabletop Exhibition on Printed Devices and Applications, Orlando, Florida, USA, February 25‐27, (2009).

3. Research 3.1 Theses

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