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

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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.