Glass Transition Behavior of PS Films on Grafted PS Substrates

摘要

We present experimental results for the glass transition behavior of polystyrene (PS) films on grafted PS layers of the same chemical identity as a function of film thickness. Our results suggest that the T_g of PS films on brush substrates decreases with decreasing film thickness. The thickness dependence of T_g was observed to be more pronounced for the films on the shorter brushes with the high grafting density. We propose a qualitative rationalization of the observations by invoking both interfacial energy considerations as well as by adapting the percolation model for the glass transition of polymer films.