This research is a collaborative effort between an experimental NMR research group and a theoretical chemistry research group to investigate the dynamics of glassy polymers. The experimental group will combine existing techniques of modern solids NMR with new experiments (rotational-echo, double-resonance C-13--F-19 NMR and rotational-echo dephasing H-1 NMR) to investigate the dynamics of 180o flips of the main-chain phenyl rings in polycarbonates and polycarbonate-like plastics. These systems will be investigated under a variety of physical conditions including high external hydrostatic pressure. Chains will be examined in bulk and at polymer-polymer interfaces. Phenyl ring flips are of interest because they monitor the slow density fluctuations of the solid, which are related to physical properties such as toughness. To understand these density fluctuations in detail, a parallel set of computational experiments using a Generalized Langevin Dynamics simulation technique will be undertaken. This method of computer simulation has been specifically developed to allow the simulation of slow motions in a glassy solid.
