Relaxation dynamics in thin supported polymer films

Abstract The glass transition and relaxation dynamics of thin polymer films supported on a substrate have been investigated for three different polymers, atactic polystyrene, poly(vinyl acetate), and atactic poly(methyl methacrylate) by using dielectric relaxation and thermal expansion spectroscopy. The temperature, T α , at which the imaginary component of the susceptibility has a peak due to the α-process at a fixed frequency, is measured as a function of thickness and the molecular weight of the polymers. The observed thickness and molecular weight dependence of T α is discussed in comparison with that of T g observed in the freely standing films of polystyrene.