Slip-controlled thin-film dynamics

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 μm on OTS- and between 300 nm and 10 μm on DTS-covered silicon wafers. The slip length decreases with temperature. The obtained values for the viscosity are consistent with independent measurements.