Think globally, act locally: How interfaces can alter mobility and glassiness

This talk will focus on links between changes in local mobility and free volume as interfaces are introduced, and how those changes translate into altering dynamic relaxation and the glass transition. We have recently shown that the Cooperative Free Volume (CFV) theory can resolve bulk dynamic relaxation data over a broad temperature and pressure range, including the span from Arrhenius to non-Arrhenius behaviour. An extension to thin films will be introduced and applied to experimental dielectric relaxation data. Turning to simulation, we have previously demonstrated that the Limited Mobility (LM) model successfully predicts the impact of one or two free surfaces on the glass transition of a thin film, as well as the asymmetric effect on local mobility of an interface between two materials having different glass transition temperatures. We now turn to the modeling of interfacial effects caused by introducing additives into a bulk sample. Results will be presented linking the un/favourability of very short-range polymer-additive interactions to sample-wide changes in glassiness and local mobility. Close connections between LM predictions and experimental results will also be discussed.