(597c) Dynamics of a Supported Polycarbonate Thin Film Via Atomistic Simulation: Film Thickness and Temperature Effects

Polymeric materials are modified from bulk structural, dynamic, and thermodynamic behavior by the presence of an interface. The properties of the interface can prove beneficial or detrimental in applications such as polymer composites. These materials combine a polymer matrix with a fiber or filler material and the performance of the composite greatly depends on the characteristics of load transfer across the interface between the polymer and the filler. This may lead to either greater toughness or a more brittle behavior based on the specific interactions. Here, we use atomistic molecular dynamics to study a model interfacial system of a supported thin film of polycarbonate (PC) on a silica surface. We bin measurements of structure and dynamics of the PC as a function of distance from the silica surface over a range of temperatures (from the melt to the glass) in films of varying PC thickness and look at the effect of these variables on the glass transition temperature, T_g. We compare these measurements to the bulk behavior of PC to identify signatures of the interphase, or the three-dimensional region near the silica surface where PC behavior differs from the bulk. A comparison is made to experimental measurements of PC thin film dynamics.