Dewetting of thin polymer films: Influence of interface evolutionF. Ziebert and E. Raphaël
Laboratoire de Physico-Chimie Théorique - UMR CNRS Gulliver 7083, ESPCI - 10 rue Vauquelin, F-75231 Paris, France, EU
received 7 April 2009; accepted in final form 22 April 2009; published May 2009
published online 20 May 2009
The dewetting dynamics of ultrathin polymer films, e.g., in the model system of polystyrene on a polydimethylsiloxane-covered substrate, exhibits interesting behavior like a fast decay of the dewetting velocity and a maximum in the width of the built-up rim in the course of time. These features have been recently ascribed to the relaxation of residual stresses in the film that stem from the nonequilibrium preparation of the samples. Recent experiments by Coppée et al. on PS with low molecular weight, where such stresses could not be evidenced, showed however similar behavior. By scaling arguments and numerical solution of a thin-film viscoelastic model we show that the maximum in the width of the rim can be caused by a temporal evolution of the friction coefficient (or equivalently of the slip length), for which we discuss two possible mechanisms. In addition, the maximum in the width is affected by the sample age. As a consequence, knowing the temporal behavior of friction (or slip length) in principle allows to measure the aging dynamics of a polymer-polymer interface by simple dewetting experiments.
68.60.-p - Physical properties of thin films, nonelectronic.
68.15.+e - Liquid thin films.
83.10.-y - Rheology: Fundamentals and theoretical.
© EPLA 2009