DEWETTING DYNAMICS AT A POLYMER-POLYMER INTERFACE

We have studied the dynamics of dewetting at the interface between pol ystyrene (PS) and poly(methyl methacrylate) (PMMA) as a function of th e molecular weights of the two materials. Optical microscopy and atomi c force microscopy have been used to follow the dewetting process and to image both the surface and interfacial structure in the vicinity of the growing holes. We determined the scaling behavior of the dewettin g velocity as a function of the molecular weight of the dewetting spec ies (PS). Different regimes are found depending on the PMMA molecular weight. For large PMMA molecular weights the dewetting velocity scales inversely with the PS viscosity, while for low PMMA molecular weights , the dewetting velocity is almost independent of the PS viscosity. Th e experimental data are in quantitative agreement with recent theoreti cal predictions.