Frictional forces between strongly compressed, non-entangled polymer brushes: Molecular dynamics simulations and scaling theory

A. GALUSCHKO; L. SPIRIN; T. KREER; A. JOHNER; CLAUDIO PASTORINO; J. WITTMER; J. BASCHNAGEL

LANGMUIR

AMER CHEMICAL SOC

Año: 2010 vol. 26 p. 6418 - 6429

0743-7463

By means of molecular dynamics simulations and scaling theory we study the response of opposing polymer brushesto constant shear motion under good solvent conditions. Model systems that contain explicit solvent molecules(Lennard-Jones dimers) are compared to solvent-free systems while varying of the distance between the grafted layersand their molecular parameters, chain length and grafting density. Our study reveals a power-law dependence ofmacroscopic transport properties on the Weissenberg number,W, beyond linear response. For instance, we find that thekinetic friction constant scales as μ∼W^0.57 for large values of W.We develop a scaling theory that describes our data andprevious numerical data including recent experiments.