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 r
esult 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.
Experiments on dewetting thin polymer films confirm the theoretical prediction that thermal noise can strongly influence characteristic time-scales of fluid flow and cause coarsening of typical length scales. Comparing the experiments with determinis
tic simulations, we show that the Navier-Stokes equation has to be extended by a conserved bulk noise term to accomplish the observed spectrum of capillary waves. Due to thermal fluctuations the spectrum changes from an exponential to a power law decay for large wavevectors. Also the time evolution of the typical wavevector of unstable perturbations exhibits noise induced coarsening that is absent in deterministic hydrodynamic flow.
