Alternative dissipation mechanisms and the effect of the solvent in friction between polymer brushes on rough surfaces

Sissi De Beer* (Corresponding Author), Martin H. Müser

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

21 Citations (Scopus)

Abstract

Surfaces covered with end-anchored polymers under good solvent conditions have excellent tribological properties. The friction between such surfaces is commonly attributed to steady-state interdigitation of the opposing polymer brushes. However, this conclusion tends to be based on idealized geometries neglecting surface roughness. Using molecular dynamics simulations, we find that there are qualitative differences between the friction of rough and flat polymer-brush surfaces. For rough surfaces the dissipation due to transient interdigitation and capillary- and shape-hysteresis is just as important or can even dominate over steady-state interdigitation. Having a mix of dissipation mechanisms that are all intertwined affects the observed friction force in linear-response as well as in the shear-thinning exponents and effective viscosity. Moreover, we find that the effect of the solvent viscosity is sublinear.

Original languageEnglish
Pages (from-to)7234-7241
Number of pages8
JournalSoft matter
Volume9
Issue number30
DOIs
Publication statusPublished - 14 Aug 2013
Externally publishedYes

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