Surface Relaxation of Vapor Deposited Polystyrene Glasses

Our laboratory has recently reported the technique of preparing stable glass films of polymers through PVD and the exceptional properties of such products. This technique is in principle applicable to a wide range of polymers, and it has been demonstrated for polystyrene and poly(methyl methacrylate). Stable glasses are known to have higher density and enhanced kinetic stability compared to ordinary glasses, but less is known about their surface dynamics given the fact that polymer glasses have higher surface mobility compared to their bulk counterparts. In studies of surface dynamics, atomic force microscopy (AFM) is commonly used to characterize the relaxation of surface perturbations. Here we use AFM to probe the temporal evolution of surface structure of vapor deposited polystyrene stable glasses. By varying the stability of the glasses, we are able to better understand how surface dynamics depends on the glass stability. By controlling the temperature of relaxation and other parameters, we explore the mechanism under a wide range of experimental conditions.