Packing, Local Order, and Dynamic Processes in Glassy Polymers

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9729734 Schaefer This project involves the combination of solid-state, magic-angle spinning, dipolar-recoupling NMR experiments, with generalized Langevin dynamics simulations, for the characterization of the chain motion of a new generation of engineering polymers. The polymers are based on polycarbonate-like structures that have enhanced mechanical or optical properties. The NMR is used to measure interchain distances that act as constraints on the molecular dynamics simulations. This combination of experiment and theory should lead to a better understanding of the connection between microscopic chain motion and macroscopic polymer properties. The specific systems whose chain dynamics will be investigated are: (i) polycarbonates with specifically fluorinated phenyl rings; (ii) high-Tg polycarbonate-polyester block copolymers; (iii) non-linear hyperbranched polycarbonates; and (iv) polycarbonates with main and side-chain cyclohexyl rings. %%% The polymers that will be characterized by solid-state NMR and molecular dynamics simulations in this proposal are of current interest to industry. A tough, cheap replacement for polycarbonate that has a lower birefringence to enable more information to be packed on compact disks is a commercial goal for a number of industries.. The ability to combine theory and experiment in fundamental work on problems that also are of great practical interest guarantees an efficient transfer to the American materials industry of the basic polymer science and technology developed at Washington University under NSF sponsorship. ***