Heterogeneous nature of the dynamics and glass transition in thin polymer films.

摘要: Recent experiments have demonstrated that the dynamics in liquids close to and below glass transition temperature is strongly heterogeneous, on scale of a few nanometers. We use here model proposed recently for explaining these features, show heterogeneous nature has important consequences when considering thin films. how dominant relaxation time film changed as compared bulk, function thickness, interaction energy with substrate, temperature. The corresponding scales cover so-called VFT (or WLF) regime vary between 10-8 s 104 typically. In absence interaction, our allows interpreting suspended films experiments, case small polymers which data do not depend polymer weight. leads an increase \(T_{\rm g}\) per monomer order thermal T. This saturates at value interacting adsorption energies slightly larger still particular, we predict shift can be non-monotonous intermediate strength.