Synthesis and NMR Studies of Linear Polycarbosilanes-CeramicPrecursors and Novel Polymeric Materials

在这个由化学部特别项目办公室资助的项目中，Interrante和Apple将研究由聚硅乙烯(PSE)衍生的一系列独特的聚碳硅烷的合成、结构和热解，PSE是生产化学计量碳化硅的先驱。开环聚合(ROP)将成为合成聚碳硅烷的有效途径。溶液和固态核磁共振波谱将提供有关PSE和其他硅基聚合物的分子结构和晶体结构的信息，以及它们的一些陶瓷前驱体和陶瓷热解产物。这项研究将使系统研究一类新兴的无机/有机聚合物，有效地弥合全碳链聚合物(如聚乙烯)和以硅为基础的无机聚合物(如聚硅烷或聚硅氧烷)之间的差距。碳化硅是一种具有高强度和高模数的材料，能够在实际应用中(如燃气轮机)在高温下工作。碳化硅也是一种目标陶瓷材料，它可能是陶瓷复合材料中的纤维和基质材料。然而，在这两种情况下，由于有机硅前体的分解而产生的过量碳，都会影响最终产品的机械性能和氧化稳定性。这项研究探索了生产这些最终产品的途径，而不会产生麻烦的过量碳，从而产生具有优异材料性能的陶瓷。

In this project funded in the Special Projects Office of the Chemistry Division Interrante and Apple will investigate the synthesis, structures, and pyrolysis of a unique series of polycarbosilanes derived from poly(silaethylene) (PSE), which is a precursor to the production of stoichiometric silicon carbide. Ring-opening polymerization (ROP) processes will be investigated and developed into an effective general route to polycarbosilanes. Both solution and solid-state NMR spectroscopy will provide information about the molecular and crystal structures of PSE and other silyl polymers as well as some of their preceramic and ceramic pyrolysis products. This study will enable the systematic study of an emerging class of inorganic/organic polymers which effectively bridge the gap between the all-carbon chain polymers, such as polyethylene, and the inorganic polymers based on silicon, such as polysilanes ald polysiloxanes. %%% Silicon carbide is a material with high strength and modulus capable of performing at high working temperatures in practical applications such as a gas turbine engine. Silicon oxycarbide is also a target ceramic material which is potentially a fiber and matrix material in ceramic composites. However, in both cases excess carbon, which results from decomposition of the organosilicon precursors, affects both the mechanical properties and oxidative stability of the end products. This research investigates routes to producing these end products without the troublesome excess carbon, resulting in ceramics with superior material properties.