RUI: Synthesis of Amine-Terminated Polydimethylsiloxanes and Block Copolymeric Silicones

通过引发环状三聚体六甲基环三硅氧烷与含保护氮的锂碱的阴离子聚合，可以制备分子量分布窄、具有伯胺和仲胺端基的聚二甲基硅氧烷。聚合后，保护基团被去除，氨基端的有机硅将转化为嵌段共聚物。这种共聚物将由橡胶硅烷链段和应进行微相分离的极性刚性链段组成。将制备有机硅-聚氨酯和有机硅-聚脲嵌段共聚物。这些将通过小角x射线散射、热-机械分析和动态-机械分析来检验。有机硅或硬段的相对分子质量与分离的微区尺寸和热机械性能之间的基本关系将被推导出来。这项研究项目是NSF加强对本科生研究支持的努力的一部分。

Polydimethylsiloxanes of narrow molecular-weight distribution and with primary and secondary amine end groups will be prepared by initiating the anionic polymerization of the cyclic trimer, hexamethylcyclotrisiloxane, with lithium bases containing protected nitrogen. After polymerization, the protecting group will be removed and the amino-ended silicones will be converted to block copolymers. Such copolymers will be composed of rubbery silicone segments and polar, rigid segments which should undergo microphase separation. Silicone- polyurethane and silicone-polyurea block copolymers will be prepared. These will be examined by small-angle x-ray scattering, thermal-mechanical analysis, and dynamic-mechanical analysis. Fundamental relationships between molecular weight of silicone or hard segment and separated domain size and thermal- mechanical properties will be derived. This research project is part of the NSF effort to enhance support for undergraduate research.