Size and interface effects on several kinetic and thermodynamic properties of polymer thin films

摘要

Size and interface effects on kinetic and thermodynamic properties (shear viscosity [μ(T,D)], surface tension [γ(T,D)] and thermal expansion coefficient [β(T,D)]) of thin polymer films at temperature T have been modeled based on free volume model and size-dependent function for mean-square displacement of molecules in thin polymer films at glass transition temperature σ_g~2(Z)), where D denotes the thickness of thin films. In terms of these models, η(T,d), β(T,D) and γ(T,D) functions are predicted to decrease or increase as D decreases in comparison with the corresponding bulk values, depending on free surface effect and film/substrate interface interaction strength. The predictions are in agreement with available experimental measurements of polystyrene and polybutadiene thin films.