Slip-controlled thin film dynamics

TL;DR

This paper introduces a new method to measure slip length and viscosity in highly viscous thin polymer films by analyzing dewetting fronts, providing insights into slip behavior and film properties.

Contribution

A novel approach using a thin film model to quantitatively determine slip length and viscosity from dewetting dynamics of polymer films.

Findings

Slip lengths range from 100 nm to 10 microns.

Slip length decreases with increasing temperature.

Viscosity measurements agree with independent methods.

Abstract

In this study, we present a novel method to assess the slip length and the viscosity of thin films of highly viscous Newtonian liquids. We quantitatively analyse dewetting fronts of low molecular weight polystyrene melts on Octadecyl- (OTS) and Dodecyltrichlorosilane (DTS) polymer brushes. Using a thin film (lubrication) model derived in the limit of large slip lengths, we can extract slip length and viscosity. We study polymer films with thicknesses between 50 nm and 230 nm and various temperatures above the glass transition. We find slip lengths from 100 nm up to 1 micron on OTS and between 300 nm and 10 microns on DTS covered silicon wafers. The slip length decreases with temperature. The obtained values for the viscosity are consistent with independent measurements.