| Surfaces coated with polymer brushes in a good solvent are known to exhibit excellent tribological properties. We have performed coarse-grained equilibrium and nonequilibrium molecular dynamics (MD) simulations to investigate dextran polymer brushes in an aqueous environment in molecular detail. In a first step, we determined simulation parameters and units by matching experimental results for a single dextran chain. Analyzing this model when applied to a multichain system, density profiles of end-tethered polymer brushes obtained from equilibrium MD simulations compare very well with expectations based on self-consistent field theory. Simulation results were further validated against and correlated with available experimental results. The simulated compression curves (normal force as a function of surface separation) compare successfully with results obtained with a surface forces apparatus. Shear stress (friction) obtained via nonequilibrium MD is contrasted with nanoscale friction studies employing colloidal-probe lateral force microscopy. We find good agreement in the hydrodynamic regime and explain the observed leveling-off of the friction forces in the boundary regime by means of an effective polymer.wall attraction.
for LaTeX users @article{MKSingh2015-31,
author = {M. K. Singh and P. Ilg and R. M. Espinosa-Marzal and M. Kr\"oger and N. D. Spencer},
title = {Polymer brushes under shear: Molecular dynamics simulations compared to experiments},
journal = {Langmuir},
volume = {31},
pages = {4798-4805},
year = {2015}
}
\bibitem{MKSingh2015-31} M.K. Singh, P. Ilg, R. M. Espinosa-Marzal, M. Kr\"oger, N.D. Spencer,
Polymer brushes under shear: Molecular dynamics simulations compared to experiments,
Langmuir {\bf 31} (2015) 4798-4805.MKSingh2015-31
M.K. Singh, P. Ilg, R. M. Espinosa-Marzal, M. Kr\"oger, N.D. Spencer
Polymer brushes under shear: Molecular dynamics simulations compared to experiments
Langmuir,31,2015,4798-4805 |
mk@mat.ethz.ch
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