Liquid Front Profiles Affected by Entanglement-induced Slippage

TL;DR

This paper demonstrates that slip boundary conditions, rather than viscoelastic effects, primarily cause asymmetric liquid front profiles in entangled polymer films, with slippage increasing sharply above a certain molecular weight.

Contribution

It provides experimental evidence that slip boundary conditions can explain asymmetric profiles in polymer films, challenging previous assumptions about viscoelastic effects.

Findings

Slippage increases dramatically above a certain molecular weight.

Asymmetric profiles can result solely from slip boundary conditions.

Results align with de Gennes' theoretical description.

Abstract

Hydrodynamic slippage plays a crucial role in the flow dynamics of thin polymer films, as recently shown by the analysis of the profiles of liquid fronts. For long-chained polymer films it was reported that a deviation from a symmetric profile is a result of viscoelastic effects. In this Letter, however, evidence is given that merely a slip boundary condition at the solid/liquid interface can lead to an asymmetric profile. Dewetting experiments of entangled polymer melts on diverse substrates allow a direct comparison of rim morphologies. Variation of molecular weight Mw clearly reveals that slippage increases dramatically above a certain Mw and governs the shape of the rim. The results are in accordance with the theoretical description by de Gennes.