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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

Multiscale Simulation of Polymersnear (Metal) Surfaces

K. Kremer

Max Planck Institute for Polymer Research, Mainz

09/2005

slide3

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

open source software espresso
Open Source Software: ESPResSo

Modular Simulation Package by C. Holm et al

Method development will continue!!

Extensible Simulation Package for Research on Soft matter

central topics of the theory group
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 …
slide6

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

slide7

Why Polycarbonate?

Modern application of Polycarbonate

New football stadium, Cologne, World Championship 2006

slide8

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

why study polycarbonate and the pc ni interface
Why study Polycarbonate and the PC/Ni interface?

d=λ/4

(100nm)

“only” high tech commodity polymer

specific adsorption
Specific Adsorption

Two extreme cases

end adsorption only “inert” surface

energy dominated entropy dominated

slide11
Structure Property Relations for Polymers - Linking Scales
    • Interplay universal - system specific aspects
soft matter
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

energy scale kt for t 300k
Energy Scale kT for T=300K

Electronic structure, CPMD

Quantum Chemistry

Biophysics Membranes, AFM

Spectroscopy

time and length scales

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

mixtures polymer a b
Mixtures Polymer A, B

#AA, #BB, #ABcontacts =O(N)

Phase separation, critical interaction

“chemistry”

“generic”

Intra-chain entropy invariant => small energy differences => phase separation

slide16

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)

slide17

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

polycarbonate on metal surface
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
molecular coarse graining of bisphenol a polycarbonate
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

slide21

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.

interaction energies in the coarse grained model
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

molecular coarse graining of bisphenol a polycarbonate melts
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)

results for melts n 20 120
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!

viscosity time mapping
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].
how good are generated conformation inverse mapping reintroduce chemical details
How good are generated conformation?Inverse Mapping: Reintroduce Chemical Details

Coarse grained

BPA-PC chain

All atom model

comparison simulation n scattering
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)]
polycarbonate on metal surface28
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
simulating bpa pc metal interfaces
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

cpmd propane and carbonic acid on nickel
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

cpmd benzene and phenol on nickel
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
cpmd dependence of phenol ni interaction on ring orientation
CPMD: Dependence of Phenol-Ni Interaction on Ring Orientation

Interaction verysensitive to orientation!

cpmd conclusions
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
coarse grained bpa pc with end group resolution dual scale md
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)

results chain end adsorption
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
schematic structure of end sticky melts
Schematic structure of “End-Sticky” Melts

Chains “compressed”

Chains “elongated”

Normal Bulk conformations

 Coupling Surface  Bulk?

extension i other chain ends energy entropy competition
Extension I: Other Chain EndsEnergy - Entropy Competition

Delle Site, Leon, KK, JACS, 126, 2944(2004)

line defect induced ordering
Line Defect Induced Ordering

L. DelleSite, S. Leon, KK, J. Phys. Cond. Matt.17, L53, 2005

extension iii shearing a melt
Extension III: Shearing a Melt

end adsorption energy dominated case:

phenolic chain ends

Surface Potential for Ends

slide42

Sheared melts

Both ends at surface

One end at surface

No end at surface

EPL 70, 264-270 APR 2005

extension iv jamming lubricants
Extension IV: Jamming Lubricants

BPA-PC plus 5% additives

extension iv jamming lubricants44
Extension IV: Jamming Lubricants

BPA-PC plus 5% additives

jamming lubricants
Jamming Lubricants

BPA-PC plus 5% (weight) additives under shear:

BPA-PC + 5-mers BPA-PC + DPC

Blue: major component

Yellow: minor component

jamming lubricants46
Jamming Lubricants

BPA-PC plus 5% additives under shear:

JCP 123 Art. No. 104904 SEP 8 2005

specific surface morphologies multiscale approach
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

a few challenges
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
adaptive methods changing degrees of freedom on the fly
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

adaptive methods changing degrees of freedom on the fly50
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

slide51

Requirements

  • Same center-center g(r)
  • Same mass density
  • Same Pressure (=>Eq. of state)
  • Same temperature
  • Free exchange between regimes
  • Simple two body potential
  • Can be viewed as 1st order phase

transition

  • Phase equilibrium
  • Thermostat has to provide/take out

latent heat due to change in degrees

of freedom

coarse grained model
Coarse Grained Model

Study explicite atom and CG system

seperately

=> fit CG Interaction Potential:

ex = cg, pex=pcg, Tex=Tcg

transition regime
Transition Regime

explicit hybrid coarse grained

Interactions

explicit-explicit

CG-CG

hybrid-hybrid

CG- hybrid: CG-CG

explicit-hybrid: explicit-explicit

slide55

Particle Exchange

Radial Distributions,

Number of neighbours

adaptive methods changing degrees of freedom on the fly56
Adaptive Methods:Changing degrees of freedom on the fly
  • Practical proof of principle

Many open questions:

  • Higher densities
  • “real” systems
  • Inhomogeneous systems
  • Dynamics
  • Other geometries
  • Multi level systems
a few challenges57
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
solute solvent systems van der vegt dellesite
Solute Solvent Systemsvan der Vegt, DelleSite

Combined CPMD and atomistic simulations

for benzene adsorption out of water

=> Extension to more complicated systems

ad desorption process
Ad-/Desorption Process

P. Schravendijk, N. van der Vegt, L. Delle Site, KK, ChemPhysChem 6, 1866 (2005)

a few challenges60
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