Dynamic surface decoupling in a sheared polymer melt

TL;DR

This paper investigates how surface structure and polymer chain behavior influence friction in a sheared polymer melt, revealing mechanisms like chain disentanglement, surface potential effects, and chain desorption that affect slip and stick conditions.

Contribution

It introduces the concept of dynamic surface decoupling, showing how adsorbed polymer layers can modulate friction through mechanisms like chain movement and desorption.

Findings

Surface potential allows chain movement along equipotential lines.

High shear rates cause partial chain desorption.

Adsorbed layers can be tuned to control friction.

Abstract

We propose that several mechanisms contribute to friction in a polymer melt adsorbed at a structured surface. The first one is the well known disentanglement of bulk polymer chains from the surface layer. However, if the surface is ideal at the atomic scale, the adsorbed parts of polymer chains can move along the equipotential lines of the surface potential. This gives rise to a strong slippage of the melt. For high shear rates chains partially desorb. However, the friction force on adsorbed chains increases, resulting in quasi-stick boundary conditions. We propose that the adsorbed layers can be efficiently used to adjust the friction force between the polymer melt and the surface.