Non-oxide porous ceramics exhibit many unique and superior properties, such as better high-temperature stability, improved chemical inertness/corrosive resistance, as well as wide band-gap semiconducting behavior, which lead to numerous potential applications in catalysis, high temperature electronic and photonic devices, and micro-electromechanical systems. Currently, most mesoporous non-oxide ceramics (e.g. SiC) are formed by two-step templating methods, which are hard to adjust the pore sizes, and require a harmful etching step or a high temperature treatment to remove the templates. In this dissertation, we report a novel technique for synthesizing hierarchically mesoporous non-oxide SiC ceramic from a block copolymer precursor. The copolymer precursors with vairing block length were synthesized by reversible addition fragmentation chain transfer polymerization. The block copolymers self-assemble into nano-scaled micelles with a core-shell structure in toluene. With different operation processes, hollow SiC nanospheres and bulk mesoporous SiC ceramics were synthesized after the subsequent pyrolysis of precorsur micelles. The resultant SiC ceramics have potential applications in catalysis, solar cells, separation, and purification processes.The polymer synthesis and pyrolysis process will investigated by NMR, FTIR, GPC, TEM, and TGA/DSC. The morphology and structure of synthesised SiC hollow spheres and mesoporous ceramics were analyzed by SEM, TGA/DSC and BET/BJH analysis. Besides forming core shell micelles in selective solvent Toluene, we found that PVSZ-b-PS could also exhibit this property in the air water interface. By inducing the Langmuir-Blodgett deposition, a precursor monolayer with homogeously distributed povinylsilazane particles deposited on silicon wafer synthesized by spreading the diblock copolymer PVSZ-b-PS in the air water interface. After the pyrolysis process, orderly arranging SiC nano particles formed from the polymer precursor monolayer doped on the surface of silicon wafer, which shows great potential as an optoelectronic material. The deposition process and the relationship between compress pressure and monolayer morphology were studies, and the structure of monolayer and SiC dots were investigated by AFM, SEM.
| Identifer | oai:union.ndltd.org:ucf.edu/oai:stars.library.ucf.edu:etd-5769 |
| Date | 01 January 2014 |
| Creators | Yang, Xueping |
| Publisher | STARS |
| Source Sets | University of Central Florida |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Electronic Theses and Dissertations |
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