Packing, Local Order, and Dynamic Processes in Glassy Polymers

9729734 Schaefer该项目将固态、幻角旋转、偶极重新耦合核磁共振实验与广义朗之万动力学模拟相结合，用于表征新一代工程聚合物的链运动。聚合物是基于具有增强的机械或光学性能的聚碳酸酯类结构。核磁共振被用来测量作为分子动力学模拟约束的链间距离。这种实验和理论的结合应该能更好地理解微观链运动和宏观聚合物性质之间的联系。将研究其链动力学的具体体系是：(I)具有特定氟化苯环的聚碳酸酯；(Ii)高玻璃化聚碳酸酯-聚酯嵌段共聚物；(Iii)非线性超支化聚碳酸酯；以及(Iv)具有主链和侧链环己基环的聚碳酸酯。%将通过固体核磁共振和分子动力学模拟来表征本提案中的聚合物是当前工业感兴趣的。一种坚固、廉价的聚碳酸酯替代品，具有较低的双折射，使更多的信息能够存储在光盘上，这是许多行业的商业目标。在同样具有重大实际意义的问题上，在基础工作中将理论和实验相结合的能力，确保了华盛顿大学在NSF赞助下开发的基础聚合物科学和技术有效地转移到美国材料行业。***

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. ***