This proposal is a collaborative research effort between Hans-Joachim Kleebe, Colorado School of Mines and Yigal D. Blum, SRI International. The research will focus on the fundamental understanding of the fate of carbon during the pyrolysis and post-pyrolysis heat treatment of polymeric precursors to silicon oxycarbide (SiOC). The effort will combine unique synthetic and compositional control capability of preceramic polymers, with state-of-the-art characterization methodology. The proposed research will enhance the overall understanding of the relationships between synthesis, molecular content, molecular structure and nanostructure of polymeric precursors and the subsequent evolution of SiOC glasses, followed by the formation of nanosize crystallites and nanocomposite features at elevated temperatures. In contrast to previously studied sol-gel derived SiOC glasses, this project will emphasize the use of a different polymeric route based on the use of curable polyhydridomethyl-siloxane (PHMS) as a versatile and very effective precursor, and high-carbon content SiOCs. These PHMS-based materials contain very high molar ratio of carbon but exhibit unexpectedly much higher stability as solid solutions at temperatures exceeding 1400 degrees C. The overall understanding of the relationship between molecular and nanostructure of these preceramic polymers, the formation of the SiOC's vitreous network (glass architecture), the final composition, and the evolution of the polymer-derived ceramic nanostructure upon processing (crosslinking and subsequent low-temperature pyrolysis) is an essential aspect of the proposed research.
The proposed activities will have a broader impact for several growing fields in science involving materials synthesis through pyrolytic processes and R&D of organic-inorganic hybrids, nano- composites and nanophases. There will be an integrated effort to mitigate between the disciplines of organic and organometallic synthesis chemistry and solid-state ceramics. The project will provide both chemists and ceramists better guidelines in designing the properties materialss to meet specific application requirements. This scientifically based practicality will lead to a broad range of applications aiding national goals to enhance efficiency in engines and power production in a cleaner environment. Project activities will be disseminated in local newspapers, radio stations etc. in order to inform the general public of our work.
This project is co-funded with AFOSR (6.1).
