Complex Fluids Design Consortium (CFDC)
www.mrl.ucsb.edu/cfdcOverview and Update
University of California at Santa Barbara
February 2, 2010
CFDC Annual Meeting Agenda – 2/2/2010 – Morning Session
9:00-9:30 Welcome and Update (Glenn Fredrickson, Director, CFDC)9:30-10:00 Self-assembly for lithographic patterning: surfaces, interfaces, and defects (Dr. Jed Pitera, IBM Almaden)10:00-10:30 Coffee Break10:30-11:00 Mixed polymer burshes: a tool for nano-lithography? (Su-Mi Hur, UCSB)11:00-11:30 Continuum models for biomembrane dynamics (Prof. Frank Brown, UCSB)11:30-12:00 Reactions among multifunctional monomers and the gelation transition: a field-theoretic study (Aruna Mohan, UCSB)12:00-1:00 Lunch – 3rd Floor MRL patio
CFDC Annual Meeting Agenda – 2/2/10– Afternoon Session
1:00-1:30 Systematic coarse-graining of polymer field theories (Mike Villet, UCSB)1:30-2:00 Field-theoretic simulations of macrophase separation in the Gibb’s ensemble (Dr. Robert Riggleman, UCSB)2:00-2:30 Coacervation in symmetric mixtures of oppositely charged rodlikepolyelectrolytes (Dr. Rajeev Kumar, UCSB)2:30-3:00 A field-theoretic description of polyelectrolytes (Debra Audus, UCSB)3:00-3:30 Coffee Break3:30-4:00 Linear scaling methods for Kohn-Sham density-functional theory (Prof. Carlos Garcia-Cervera, UCSB)4:00-4:30 Field-theoretic model of membrane/protein assemblies (Dr. Kang Chen, UCSB)4:30-5:00 Supramolecular assembly in ternary mixtures of telechelic chains (ZoltanMester, UCSB)5:00-5:30 Unit-cell SCFT calculations of multicomponent polymer mixtures in the Gibb’s ensemble (Dr. Nate Lynd, UCSB)5:30 Adjourn CFDC meeting5:30-6:30 CFDC Steering Committee Meeting (Members Only, Rm 3117D MRL)
CFDC Dinner – 7pm Your Choice (Thai) —sign up at break
What is the CFDC?The Complex Fluids Design Consortium is an academic-industrial-national laboratory partnership aimed at developing computational tools for:
Designing soft materials at equilibrium, including polymer alloys and complex fluid formulationsAnalyzing the coupled flow, microstructure, and processing behavior of multiphase complex fluids
What do we hope to accomplish?
To create a suite of models, theoretical approaches, numerical methods, and software that:
Can be shared among the members of the consortiumCan be applied to address materials design problems and complex fluid processing problems of collective or individual interest
Objectives -- continuedCreate a world-class center for complex fluid and soft materials modelingEnhance interactions among the academic, industrial, and national lab partners and pool funding for supporting research projects of mutual interestCreate employment opportunities for the students and post-docs of the consortium
Organization and Partnership Model
UCSB is focal point for the CFDCCFDC “Steering Committee” will guide collective research agendaAcademic partners will contribute:
Time and expertiseAccess to graduate students and postdocsLeveraged funding though subject related grants
National lab partners will contribute:Time and expertiseAccess to computational facilitiesFunding though DOD/DOE programs
Partnership Model -- continued
Industrial partners will contribute:Staff timeComputational resourcesFunding
As a sustaining member (shared project)As a full member (dedicated project)
UCSB ParticipantsGlenn Fredrickson, Chem. Engr. & Materials (Polymer physics, field theory, mesoscopic simulations)Hector Ceniceros, Mathematics (Numerical methods, multiscale PDEs, computational fluid mechanics)Carlos Garcia-Cervera, Mathematics (Numerical methods, stochastic PDEs)Edward J. Kramer, Materials & Chem. Engr. (Polymer physics experiment, diffusion, interfaces, mechanical properties)Others, as per interest
National Lab ParticipantsLos Alamos National Laboratories (LANL)
Paul Welch (MD, multiscale simulations)Kim Rassmussen (SCFT, multiscale simulations)
Sandia National Laboratories (SNL)Amalie Frischknecht (Density functional theory, PRISM)Gary Grest (MD, MC of polymers)
Other Academic CollaboratorsAndrei Gusev, Materials, ETH Zurich
Finite element methodsComposite media modeling (Mechanical, transport, and optical properties)
Eric Cochran, Chemical Engineering, Iowa StateSCFT theory, algorithms, and softwareExperimental polymer physics
David Wu, Chemistry and Chemical Engineering Depts., Colorado School of Mines
Molecular simulationsPRISM
Industrial Partners 10-11Kraton Polymers (Full)DSM (Project 1, Full) DSM (Project 2, Full)Accelyrs (Sustaining)
Possible new members: Michelin, Intel, Micron, TSRC, JSR
Past members: Dow Chemical, Mitsubishi Chemical, Arkema, Rhodia, Nestle Research, GE CR&D
CFDC Steering Committee 2/10
Carl Willis (Kraton)Stephen Todd (Accelrys)Kim Rasmussen (LANL)Amalie Frischknecht (SNL)Paul Steeman (DSM)Andrei Gusev (ETH)Glenn Fredrickson (UCSB), Chair
Update--Leveraged ActivitiesInstitute for Collaborative Biotechnologies (ICB)
Our grant was renewed for 09-10 to support a project on polyelectrolyte complexation
Rajeev KumarIGERT Program of the NSF in Computational Soft Materials
A group of UCSB faculty participated in a proposal for graduate training in computational science and engineering of soft materials (Main PI: Joan Shea)
Our proposal was not selected in 2009, but we are reapplyingCenter for Functional Engineered Nanoscale Architectures (FENA) at UCLA (SRC & DARPA funding)
Fredrickson and Carcia-Cervera are co-PIs on a program in modeling of block copolymer lithography; Hawker and Kramer are co-PIs on a parallel experimental program
Simulations of graphoepitaxy/liquid-xtal hybrids (J. Lee – new student)Experimental studies of new formulations (K. Barteau – new student)
Sandia National LabsWe have a continuing project with A. Frischknecht on patterning surfaces via mixed polymer brushes (S. Hur)
Institute for Multiscale Materials Science (IMMS) – UCSB/LANLWe have an ongoing project with Rasmussen and Welch on field-based simulations on the RoadRunner architecture, and modeling of artificial membranes (K. Chen)
Leveraged Activities – Ctd.Materials Research Laboratory (NSF MRSEC)
Several of the PIs participate in MRL programs and have access to MRL computational facilities. The MRL was renewed for 2006-2012 at $20.5MThe MRL computing facility has merged with that of the California Nanosystems Institute (CNSI)
The combined CNSI/MRL facility successfully competed in the 2009-10 NSF MRI-R2 proposal (F. Brown, PI) for a new 10+TF supercomputer to be installed in 2010
Important and emerging applications of block copolymers
Driven by the versatility of molecular design and improved catalysts/synthetic methods, the applications of block copolymers have expanded widely
Medical materials, e.g. grafts & stents (Innovia, Boston Sci.)
Advanced patterning, “b.c. lithography” (IBM, Hitachi)
Thermoplastic elastomers, pressure sensitive adhesives (Kraton, JSR)
Water and energy materials (Siemens, GE)
Scales and Approaches to Fluids Simulation
Sub-atomic< 1Å
Fields(wavefunctions, density functionals)
Ab initio quantum chemistry, electronic structure
Atomic to mesoscopic1Å -- 1µm
Particles(positions, momenta)
Classical MD, MC, BD
Continuum> 1µm
Fields(densities, velocities, stresses)
PDEs of mass, momentum, energy flow, elasticity
We are computing with fields in the atomic-mesoscopic regime!
Scale MethodDOF
From Particles to Fields
We use formally exact “Hubbard-Stratonovich” and related transformations to convert from a particle-based model to a field-based model of an equilibrium fluid, simple or complexThis transformation can be realized in any ensemble, e.g.
Effective Hamiltonian H[w] contains the same information about interactions and polymer architecture as in the original model described by U
Why Field-Based Simulations of Polymer Fluids?
Relevant spatial and time scales cannot be accessed by atomistic “particle-based” simulationsUse of fluctuating fields, rather than particle coordinates, has potential computational advantages:
Simulations become easier at high density & high MWMore seamless connection to continuum mechanics Systematic coarse-graining by numerical RG appears feasible
Copolymer nanocompositeBJ Kim `06
Microemulsion, Bates ‘97
Mean-Field Approximation: SCFT
• SCFT is derived by a saddle point approximation to the field theory:
• The approximation is asymptotic for
• We can simulate a field theory at two levels:
• “Mean-field” approximation (SCFT): F ≈ H[w*]
• Full stochastic sampling of the complex field theory: “Field-theoretic simulations” (FTS)
High-Resolution SCFT
By the above methods we can compute saddle points using ~107 or more plane waves
Unit cell calculations for high accuracy with variable cell shape to relax stress
Initial condition has desired symmetry
Large cell calculations for exploring self-assembly in new systems
Initial condition is randomComplex geometries can be addressed with a maskingtechnique
A. Bosse
E. Cochran
T. ChantawansriSPHEREPACK
Highlights:
Method Development
Systematic Coarse-Graining/RG(Mike Villet)
Mike is developing methods whereby field theory models can simulated on successively coarser lattices by reparameterizingthe coarsened theory to embed fine-scale physics. This will ultimately allow very large scale simulations to capture structure and correlations over a huge range of spatial scales.
• Originally developed for particle simulations
• MC in two separate cells:
• The boxes exchange chemical species and volume, nVT overall
• At coexistence, each box contains a different bulk phase
• No interfacial effects - smaller simulation boxes
Phase coexistence:
Phase Equilibria in the Gibbs Ensemble:(Rob Riggleman, Nate Lynd)
I II
at equilibrium:
A. Z. Panagiotopoulos, Mol. Phys. 61 813 (1987)
UV DivergencesSimulations that sample field fluctuations (FTS) are sometimes plagued by ultraviolet divergences:
As the lattice spacing is decreased, some physical quantities increase without bound, e.g. chemical potential, free energy, orosmotic pressure
In the past, we have taken great pains to cancel these singular features by complicated “regularization” procedures Over the past year, it has become increasingly apparent that a simpler procedure is to avoid singular pair potential functions,e.g.
This would seem to eliminate all uv divergences, although it requires resolving the fields below the scale of b
Field-based simulations on cell processors (K. Chen)With K. Rasmussen and P. Welch of LANL, Kang has successfully ported an SCFT code to LANL’s “Roadrunner” cluster of cell processors Each node is essentially a Sony PlayStation!An 8x speed up per node over a single Opteron was obtainedWe are aiming at a demonstration project that investigates 2d melting phenomena in a large area block copolymer film
Highlights:
Applications
“Unnatural” Block Copolymer Morphologies:poly-HIPE Structures
• In collaboration with Kraton Polymers, Nate Lynd and Folusho Oyerokunworked on the design of novel PS-PB and PS-PI “Mikto-Polymers” that maintain the PS domains discrete at very high volume fraction:
– Stronger elastomers, but with good elastic recovery– Better thermal stability
• Such block copolymers could also function as ideal “AB” surfactants in blends with A and B homopolymers to stabilize poly-HIPE structures!
B
S
SS
In conventional SBS triblockcopolymers, the PS domains are only discrete (discontinuous) for fS < 0.3
SCFT Phase Diagram (n=3 arms)χN =40
Block length asymmetry:
Optimal design:
τ ≈ 0.9, PS phase discrete at fS > 0.6!!
Faceted Domains, like HIPE!!
τ = 0.9, fS = 0.66, n=5
N. Lynd, F. Oyerokun
Kraton Polymers
Block Copolymer LithographyS. Hur, K. Barteau, J. Lee
Nealey et al., Science, 2008, 321, 936 Ross et al., Science, 2008, 321, 939IBM Airgap Technique
Coating Ordering Development
31
Requirements for Block Copolymer Lithography
Improved long range dimensional control and low frequency line edge roughness
Improved resolution and linear density
Be able to fabricate a basis set of essential features
Fabricated features with multiple sizes and pitches in the same layer in different regions of a chip
Characterized and quantified defects levels
Placement accuracy: satisfying alignment and registration tolerances
Demonstrated a proof of concept for achieving throughput requirements, either via single wafer or batch processing: average net throughput of ~1 wafer per 1-2 minutes
Demonstrated potential extensibility beyond the 10 nm ITRS technology generation
Satisfied projected ITRS etch and pattern transfer requirements for fabricating electronically useful features
Demonstrated ease of integration and an enhanced process window
International Technology Roadmap for Semiconductors
32
AB + A + Confinement
Evolution of total A-segment A-homopolymer
segment concentration
S. Hur et al. Macromolecules, 42 (15), 5861–5872, 2009
Bended Lamellar Structure
AB + A-attractive wall
+ A (α = 0.5 (NAh/N), VAh=0.2)
~ 12 .7Rg
A-homopolymersegment concentrationfA = 0.7, L = 23 Rg , B wetting wall
α =1.75 (NAh/N) , VAh = 0.23
Square Ordered Cylinders
33
Line Edge Roughness Effects
Conclusion: Tetragonal order is robust, except against long-wavelength boundary perturbations of large amplitude
A. Onikoyi , E. J. Kramer (2008)
The top-down lithography used to create wells will leave rounded corners and line edge roughnessWhat will be the impact on self-assembly?
Su-mi Hur
34
New Block Copolymer Formulations
In collaboration with the Hawker and Kramer groups, we have designed new AB + B’C copolymer blends that form square lattices at equilibrium & without confinement!Current experimental design is based on a supramolecular diblock blend
Relies on H-bonding between hydroxy-styrene (hS) and 4-vinyl pyridine (4VP) to suppress macrophaseseparation
C. Tang, E. Lennon, G. Fredrickson, C. Hawker, E. Kramer, Science 322, 429 (2008)
Remove A Remove A & COriginal film
35
Laterally Confined Mixed Polymer Brushes
Mixed polymer brushes without confinement
~ μm ~ nm
Usov et al, Macromolecules, 200730 Rg
3Rg
Laterally confined by pure brush region
Amalie Frischknecht et al., Project Proposal of Sandia National Lab.
Mixed polymer brushes with confinement
36
Gradient in Grafting Density Ratio
Rapid ramping
fraction of A in grafting
Slower ramping
fraction of A in graftingSlower ramping and smaller χABN
1
0
1
0
Further slower ramping
37
Free Boundaries: Polymer/Air Interfaces
SCFT preliminary result with a void component addition
Park et al. Macromolecules , 42, 5895, 2009A. Horvat et al. Macromolecules, 40(19), 6930, 2007
Lamella forming block copolymer on a A-attractive substrate with different film thickness – island and hole formation leading to non-uniform surface
The supramolecular diblock system
T (1/χN)
z h/χN
1. Calculated within the SCFT (mean-field) approximation
2. Note the trend with N: re-entrance for longer chains.
NA =NB, zA=zB symmetric case
Feng, E. Lee, W., and Fredrickson, G. H., Macromolecules, 40, 693-702, 2007.
Advances in Supramolecular Polymer Theory(A. Mohan, R. Elliott, Z. Mester)
Richard completed a study of a binary telechelic blend model:A distribution of lengths and compositions of linear chains are producedAll such chains are enumerated by coupled linear integral equationsA rich interplay of macrophase and microphase separation is manifest
Zoltan has generalized the approach to a 3-component mixture that is a model for DSM’s Arnitel copolyester elastomer
Aruna has developed a related, but more complex formalism for inhomogeneous networks produced by linking polymers with functionality higher than 2
Her approach requires the solution of coupled nonlinear integral equations to enumerate all tree-like structuresThe first generalization of classical Flory-Stockmayer theory to inhomogeneous systems!Applications will include IPNs, surface states and structures of gels and networks, microphases and syneresis phenomena in gels
Polyelectrolyte Complexation: Complex Coacervates (D. Audus, R. Kumar, R. Riggleman)
Aqueous mixtures of polyanions and polycations complex to form dense liquid aggregatesFluctuation-dominated: SCFT fails!Applications include:
Food/drug encapsulationDrug/gene delivery vehiclesPurification/separationsBio-inspired adhesives
Cooper et al (2005) CurrOpin Coll. & Interf. Sci.10, 52-78.
H. Waite (UCSB) “Sandcastle worms”
+ + +
--
-
Activities in Polyelectrolyte ComplexationDebra Audus
Development of models that account for changes in counterion condensation upon complexationValidation of models in context of experiments by the Tirrellgroup
Rajeev KumarTheory of complexation of rodlike PEs – role of chain flexibilityTheory of interfacial properties between coacervate and supernatent
Rob RigglemanFTS simulations of coacervate-supernatent interfacesSimulations of complexation in PE block copolymers
Block Copolymer Morphology Change Induced by Nanoparticles
By adding PS coated nanoparticles
Hybrid Particle/Field Simulations PS-b-P2VP 58k-57k/ Au-PSLow particle conc. Low particle conc.
High particle conc. High particle conc.
Lamellar
HexagonalBJ Kim, SW Sides, EJ Kramer, GH Fredrickson, PRL 96, 250601 (2006)
Software statusWe have consolidated some of our software in one modular C++ code (Cochran code) and have implemented a CVS server for version control, bug fixesCurrent capabilities
SCFT for arbitrary tree-like branched architectures, solvents, blends, copolymers in canonical and GC ensemblesFTS of binary species modelsStationary and mobile spherical nanoparticlesFilms and complex geometries by maskingDiffusive dynamics for SCFTStress distributions
Future capabilitiesFTS for arbitrary models, including polyelectrolytes and ionsSupramolecular polymers and networksContinuous polydispersityQuasi-static stress-strain properties Other ensembles, e.g. NPTThin film module with boundary conditions/Chebyshev basedGrafted polymer layersMobile non-spherical inclusionsGibbs ensemble simulationsCoarse-graining and multiscale techniquesRealistic dynamics including hydrodynamics, processing behavior
Licensing to Accelyrs
Two years ago, UCSB and Accelyrs executed an agreement to provide Accelyrs an exclusive license to market and sell our CFDC code (Cochran C++ code) as part of its Materials Studio product: MesotekDuring the past year, this partnership was terminated by mutual agreementA group at the US Army Research Labs (WMRD) in Aberdeen is funding a new postdoc for 2010-11 to continue improvement and development of the codeCFDC members will benefit from these improvementsWe are considering various long-term options for the software, including open sourcing
CFDC Annual Meeting Agenda – 2/2/2010 – Morning Session
9:00-9:30 Welcome and Update (Glenn Fredrickson, Director, CFDC)9:30-10:00 Self-assembly for lithographic patterning: surfaces, interfaces, and defects (Dr. Jed Pitera, IBM Almaden)10:00-10:30 Coffee Break10:30-11:00 Mixed polymer burshes: a tool for nano-lithography? (Su-Mi Hur, UCSB)11:00-11:30 Continuum models for biomembrane dynamics (Prof. Frank Brown, UCSB)11:30-12:00 Reactions among multifunctional monomers and the gelation transition: a field-theoretic study (Aruna Mohan, UCSB)12:00-1:00 Lunch – 3rd Floor MRL patio
CFDC Annual Meeting Agenda – 2/2/10– Afternoon Session
1:00-1:30 Systematic coarse-graining of polymer field theories (Mike Villet, UCSB)1:30-2:00 Field-theoretic simulations of macrophase separation in the Gibb’s ensemble (Dr. Robert Riggleman, UCSB)2:00-2:30 Coacervation in symmetric mixtures of oppositely charged rodlikepolyelectrolytes (Dr. Rajeev Kumar, UCSB)2:30-3:00 A field-theoretic description of polyelectrolytes (Debra Audus, UCSB)3:00-3:30 Coffee Break3:30-4:00 Linear scaling methods for Kohn-Sham density-functional theory (Prof. Carlos Garcia-Cervera, UCSB)4:00-4:30 Field-theoretic model of membrane/protein assemblies (Dr. Kang Chen, UCSB)4:30-5:00 Supramolecular assembly in ternary mixtures of telechelic chains (ZoltanMester, UCSB)5:00-5:30 Unit-cell SCFT calculations of multicomponent polymer mixtures in the Gibb’s ensemble (Dr. Nate Lynd, UCSB)5:30 Adjourn CFDC meeting5:30-6:30 CFDC Steering Committee Meeting (Members Only, Rm 3117D MRL)
CFDC Dinner – 7pm Your Choice (Thai) —sign up at break
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