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Multiscale Simulation of Polymers near (Metal) Surfaces

Multiscale Simulation of Polymers near (Metal) Surfaces. K. Kremer Max Planck Institute for Polymer Research, Mainz. 09/2005. Max-Planck Institute for Polymer Research Mainz. Molecular. Atomistic. Characteristic Time and Length Scales. Soft fluid. Time. Finite elements. bilayer

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Multiscale Simulation of Polymers near (Metal) Surfaces

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  1. Multiscale Simulation of Polymersnear (Metal) Surfaces K. Kremer Max Planck Institute for Polymer Research, Mainz 09/2005

  2. Max-Planck Institute for Polymer Research Mainz

  3. Molecular Atomistic Characteristic Time and Length Scales Soft fluid Time Finite elements bilayer buckles Length Quantum Local Chemical Properties  Scaling Behavior of Nanostructures Energy Dominance  Entropy Dominance of Properties

  4. Open Source Software: ESPResSo Modular Simulation Package by C. Holm et al Method development will continue!! Extensible Simulation Package for Research on Soft matter

  5. Central Topics of the Theory Group • Method Development, Scientific Open Source Software (ESPResSo) • Charged Systems (SFB, Transregio, Gels) • Long Range Interactions, Hydrodynamics • Membranes,….Biophysics • Multiscale Modeling • Analytic Theory of disordered Systems • Complex Fluids • Computational Chemistry of Solvent-Solute Systems • Melts, Networks – Relaxation, NEMD …

  6. COWORKERS: L. Delle Site N. Van der Vegt D. Andrienko, M. Praprotnik, X. Zhou (Los Alamaos Nat. Lab.) N. Ardikari, W. Schravendijk, M.E. Lee F. Müller-Plathe ( TU Darmstadt) O. Hahn (Würzburger Druckmaschinen) D. Mooney (Univ. College Dublin) H. Schmitz (Bayer AG) W. Tschöp (DG Bank) S. Leon (UPM Madrid) C. F. Abrams (Drexel) H. J. Limbach (Nestle) BMBF Center for Materials Simulation Bayer, BASF, DSM, Rhodia, Freudenberg

  7. Why Polycarbonate? Modern application of Polycarbonate New football stadium, Cologne, World Championship 2006

  8. Why study Polycarbonate and the PC/Ni interface? Grooves and address pits of a die cast sample of polycarbonate for a high storage density optical disc Bayer Materials

  9. Why study Polycarbonate and the PC/Ni interface? d=λ/4 (100nm) “only” high tech commodity polymer

  10. Specific Adsorption Two extreme cases end adsorption only “inert” surface energy dominated entropy dominated

  11. Structure Property Relations for Polymers - Linking Scales • Interplay universal - system specific aspects

  12. Soft Matter?? Thermal energy of particles/ per degree of freedom E=kT • Room temperature 300K: Chemical Bond Hydrogen Bond Soft Matter: Thermal Energy dominates properties

  13. Energy Scale kT for T=300K Electronic structure, CPMD Quantum Chemistry Biophysics Membranes, AFM Spectroscopy

  14. Semi macroscopic L  100Å - 1000Å T  0 (1 sec) Mesoscopic L  10Å - 50Å T  10-8 - 10-4 sec Entropy dominates Macroscopic domains etc. Microscopic L  1Å - 3Å T  10-13 sec Energy dominates (Sub)atomic electronic structure chemical reactions excited states Mesoscopic L  10Å - 50Å T 10-8 - 10-4 sec Entropy dominates Time and length scales   Properties   generic/universal *** chemistry specific

  15. Mixtures Polymer A, B #AA, #BB, #ABcontacts =O(N) Phase separation, critical interaction “chemistry” “generic” Intra-chain entropy invariant => small energy differences => phase separation

  16. Example Viscosity h of a polymer melt (extrusion processes ....) Microscopic materials/ chemistry specific Prefactor L  1Å– 3Å (e.g. function of glass transition) T  10-13 sech = A MX “Energy dominated“ « Mesoscopic generic/universal Properties L  10Å– 50Å h = A MX X = 3.4 T  10-8 – 10-4sec M molecular weight “Entropy dominated“ h= A MX varies for many decades varies for many decades • e.g.: M 2M h(2M)  10h(M) • T =500 K 470K • (T =470 K )  10 h(T = 500 K) (typical values for BPA-PC)

  17. Micro-Meso-Macro Simulation Interplay Energy  Entropy Free Energy Scale: kBT (SEMI-)MACROSCOPIC “Coarse Graining“ Inverse Mapping MESOSCOPIC Simpler Models “Coarse Graining“ Inverse Mapping TODAY ATOMISTIC/MOLECULAR

  18. Polycarbonate on Metal Surface • Linking Scales for Bisphenol-A-Polycarbonate (BPA-PC) • Molecular Coarse-Graining • Inverse Mapping, (Phenol Diffusion) • BPA-PC Melts near Nickel Surfaces • Ab initio calculations: Surface/molecule energetics • Multiscale simulation: Molecular orientation at liquid/metal interface • Adsorption at a step • Shearing a melt

  19. Molecular Coarse-Graining of Bisphenol-A-Polycarbonate • Coarse-graining:map bead-spring chain over molecular structure. => Many fewer degrees of freedom • Inverse mapping: grow atomic structure on top of coarse-grained backbone =>Large length-scale equilibrationin an atomically resolved polymer

  20. Mapping Scheme

  21. Original Ansatz 1:2 Mapping O C C O C C O O O O } Distribution Functions v v a j = a j P( l , , ) P( l )P( )P( ) v v v b j = b j P( l , , ) P( l )P( )P( ) ³ 4 10 Thermodynamic PotentialV Algorithmic speed up: ! Distributions include temperature! MD simulation at one temperature, but with variable distributions.

  22. Interaction Energies in the Coarse-Grained Model Angle potentials are T-dependent Boltzmann inversions; e.g., at carbonate: U P • Excluded volume • Bonds • Angles • Torsions T = 570 K

  23. Molecular Coarse-Graining of Bisphenol-A-Polycarbonate Melts 9.3-11.5 Å A particular conformation of a 10-repeat-unit molecule of BPA-PC at atomic resolution; 356 atoms Its coarsened representation in the 4:1 mapping scheme; 43 “beads”; ‹Rg2›1/2 = 20.5 Å; lp ~ 2 r.u. Fast motion (e.g. bond vibration) is properly averaged over; CG chain represents a multitude of underlying atomic structures C. F. Abrams, KK, Macromol. 36, 260(2003)

  24. Results for Melts, N=20….120 • Molecular Coarse-Grained Melt • Inverse Mapping End to end distance of coarse grained simulations agree to n-scattering experiments!

  25. Viscosity => Time Mapping • Melt simulation • Viscosity fromchain diffusioncoefficient • Property of entire chains • (new data 2005) • [W. Tschöp, K. Kremer, J. Batoulis, T. Bürger, O. Hahn, Acta Polym. 49, 61 (1998); ibid. 49, 75].

  26. How good are generated conformation?Inverse Mapping: Reintroduce Chemical Details Coarse grained BPA-PC chain All atom model

  27. Comparison: Simulation n-Scattering Structure factors of (deuterated) BPA-PC Right: standard BPA-PC Bottom: fully deuterated BPA-PC • [J. Eilhard, A. Zirkel, W. Tschöp, O. Hahn, K. K., O. Schärpf, D. Richter,U. Buchenau,J. Chem. Phys. 110, 1819 (1999)]

  28. Polycarbonate on Metal Surface • Linking Scales for Bisphenol-A-Polycarbonate (BPA-PC) • Molecular Coarse-Graining • Phenol Diffusion (need atomistic resolution!) • Inverse Mapping, (atomistic trajectories for entangled melts for up to 10-4sec!!) • BPA-PC Melts near Nickel Surfaces • Ab initio calculations: Surface/molecule energetics • Multiscale simulation: Molecular orientation at liquid/metal interface • Adsorption on a step • Shearing a melt

  29. Simulating BPA-PC/Metal Interfaces Molecular structure coarse-grained onto bead-spring chain Simulation of coarse-grainedBPA-PC liquids (T = 570K)next to metal surface Specific surface interactionsinvestigated via ab initiocalculations

  30. Ab initio Investigations of Comonomeric Analogues on Nickel (CPMD Program: M. Parrinello)

  31. CPMD: Propane and Carbonic Acid on Nickel Adsorption energy: +0.01 eV (0.2 kT @ 570K) for d 3.2Å Strongly repulsed, regardless of orientation propane carbonic acid

  32. CPMD: Benzene and Phenol on Nickel • Benzene: Eads = -1.05 eV (21 kT @ 570K) at d = 2 Å. • Phenol: Eads = -0.92 eV at d = 2 Å. • Both: Horizontal orientation strongly preferred, short-ranged: |Eads| < 0.03 eV for d > 3 Å

  33. CPMD: Dependence of Phenol-Ni Interaction on Ring Orientation Interaction verysensitive to orientation!

  34. CPMD:Conclusions • Strong repulsion of propane and carbonic acid • + the strong orientational dependence • + short interaction range of phenol • with Ni {111} •  • Internal phenylene comonomers in BPA-PC are sterically hindered from adsorbing on Ni {111}. • Torsional freedom in carbonate group allows for terminal phenoxy groups to adsorb

  35. Coarse-Grained BPA-PC with End-Group Resolution (Dual Scale MD) • Phenol-Ni interactionstrongly dependent onC1-C4 phenol orientation • In standard 4:1 model,phenoxy end orientationnot strictly accounted for • Resolving only the terminal carbonatesspecifies 1-4 orientationand is inexpensive Abrams CF, Delle Site L, KK, PRE 67, 021807 (2003)

  36. Results: Chain-end adsorption Chain center-of-mass density profiles • N = 10 monomers • M = 240 chains • Rg21/2 = 20.5 Å3 clear regimes: • z < Rgbulk : • both ends adsorbed • Rgbulk < z < 2Rgbulk : • single ends adsorbed • z > 2Rgbulk: • no ends adsorbed

  37. Schematic structure of “End-Sticky” Melts Chains “compressed” Chains “elongated” Normal Bulk conformations  Coupling Surface  Bulk?

  38. Extension I: Other Chain EndsEnergy - Entropy Competition Delle Site, Leon, KK, JACS, 126, 2944(2004)

  39. Extension II: Stepped Surface

  40. Line Defect Induced Ordering L. DelleSite, S. Leon, KK, J. Phys. Cond. Matt.17, L53, 2005

  41. Extension III: Shearing a Melt end adsorption energy dominated case: phenolic chain ends Surface Potential for Ends

  42. Sheared melts Both ends at surface One end at surface No end at surface EPL 70, 264-270 APR 2005

  43. Extension IV: Jamming Lubricants BPA-PC plus 5% additives

  44. Extension IV: Jamming Lubricants BPA-PC plus 5% additives

  45. Jamming Lubricants BPA-PC plus 5% (weight) additives under shear: BPA-PC + 5-mers BPA-PC + DPC Blue: major component Yellow: minor component

  46. Jamming Lubricants BPA-PC plus 5% additives under shear: JCP 123 Art. No. 104904 SEP 8 2005

  47. Specific Surface Morphologies – Multiscale Approach PC near Ni Competition Energy- Entropy Coarse-graining onto bead-spring chain Simulation of coarse-grainedpolymer next to metal surface (BPA-PC) “sticky” chain ends “neutral” Coating/contamination with oligomers Specific surface interactions ab initio calculations (CPMD) C.F. Abrams, et al. PRE 021807 (2003) L. DelleSite, et al. PRL 156103 (2002) BMBF Zentrum MatSim

  48. A few Challenges • Dual-Triple… Scale Simulations/Theory • Adaptive quantumforce fieldcoarse grained … • Nonbonded Interactions: NEMD, Morphology… • Accuracy kBTO(1/N)needed! • Conformations  Electronic Properties • E.g. coupling of aromatic groups to backbone conformation, or to other chains • Online Experiments: • Nanoscale Experiments, long Times

  49. Adaptive Methods:Changing degrees of freedom on the fly Adaptive Multiscale methods – Static and Dynamic Simple test case Polymers at surfaces, VW Foundation Project M. Praprotnik, L. DelleSite, KK, JCP, Nov. 2005

  50. Adaptive Methods:Changing degrees of freedom on the fly Tetrahedron, repulsive LJ Particles,  Hybrids  “Softer” Sphere FENE bonds Explicit Atom  Transition  Coarse Grained regime regime regime

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