  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.
