Abstract
Preparation and pyrolysis of p-diethynylbenzene-modified polymethylsilane was studied. Polymethylsilane (PMS) was modified by platinum-catalyzed hydrosilylation of PMS with p-diethynylbenzene at room temperature and characterized by spectroscopic analyses (infrared (IR) and 1H, 13C and 29Si nuclear magnetic resonance (NMR)), and thermogravimetric(TG) analysis. IR and 1H, 13C and 29Si NMR suggested that Si-H groups were reacted at two terminal groups or one terminal group of p-diethynylbenzene during hydrosilylation. TG analysis up to 1000 degree under an Ar atmosphere revealed that cross-linked PMS showed a ceramic yield of 63 mass%, while PMS showed a much lower ceramic yield (28 mass%). The drastic increase in a ceramic yield could be ascribed to a crosslinking reaction, which possibly involved the C=C groups in cross-linked PMS. The ceramic residues of modified PMS were characterized by IR spectroscopy, solid-state 13C and 29Si NMR spectroscopies with magic angle spinning technique (solid-state 13C and 29Si MAS NMR) and X-ray diffraction (XRD). IR and solid-state 13C and 29Si MAS NMR spectroscopies showed transformation of a polysilane skeleton into a carbosilane-type skeleton via the Kumada rearrangement in the temperature range from 400 to 600 degree. The mineralization process significantly proceeded in the temperature range from 600 to 1000 degree. Crystallization of SiC occurres above 1200 degree.
