Glass transition relaxations in thin suspended polymer films

Using dielectric spectroscopy, we probe the structural relaxation processes in thin freely suspended polystyrene films. For thin films we observe a relaxation scenario distinctly different from that of bulk polystyrene. The main glass transition relaxation becomes faster with decreasing film thickness, indicating a reduction in the glass transition temperature. For thin films we observe an additional process with an Arrhenius temperature dependence. This process is unique for thin freely suspended films and is not present in bulk polystyrene