● Nanocellulose can be used in different applications only by carefully selecting a favourable characteristics of the material. The nanomaterial properties are driven by its micro- and nanoscopic features, such as structure, shape, strength, ability to self-assemble,.. and surface properties as they drive the interface characteristics and by that the nature of the interactions.

● Hence, with the shift from bulk cellulose to more sophisticated applications and products, it is necessary also to introduce new methods for characterization.

● Multi-Parametric Surface Plasmon Resonance (SPR) enables characterization of dynamic changes in model cellulose thin films and gels in real-time.

MP-SPR: A new optical technique for characterization of cellulose structure and kinetic interactions

Gold, very thin polymer layersCellulose, PS, PET, PMMA, SiO2, TiO2, Al2O3, ITO, graphene, CNT, Pt, Pd, ...Thickness up to microns

Kinetics, Affinity, Concentration, Adsorption/Absorption, Desorption, Adhesion

Refractive index, Thickness, Extinction coefficient, Density, Surface coverage, Swelling, Optical dispersion

MP-SPR: A new optical technique for characterization of cellulose structure and kinetic interactions

Orelma et al, Biomacromolecules (2011) 10Malmström et.al., Macromolecules (2013)

Glass substrateAdhesion layerPlasmonic layer

Other material

Functionalization

PrismOptical interface

Flow-cell

SENSOR

Typical experiment set-up:1. Background measurement of an SPR sensor (typically SiO2 or Au)2. A model cellulose formed on the sensor (typically spin-coating or LB)3. The sensor is measured in air at two wavelengths (=> thickness and

refractive index of the cellulose layer)4. Additional protective/functional coating can be added in-situ

(electrodeposition, LbL) or ex-situ (ALD, CVD,..)5. Coated sensor is measured in air (=> thickness and refractive index of

the coating)6. Gas or vapour or liquid can be introduced (=> dynamic swelling)7. Injections of interacting samples can be introduced (=> kinetics of

binding, surface coverage, dry mass)

MP-SPR: A new optical technique for characterization of cellulose structure and kinetic interactions

Barrier coating properties

Thickness optimization Dynamic structural changes

Polymer at pH 9Polymer at pH 4Referenc at pH 9 Reference at pH 4

Interaction kinetics Surface coverage

Self-assembly

Future steps include testing of other functional characteristics also on cellulose model surfaces.

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Orelma et al, Biomacromolecules (2011)

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