Synthesis and Characterization of a Propargyl-Substituted Polycarbosilane with High Ceramic Yield

A propargyl-substituted polycarbosilane (PCS), namely, propargyl-substituted hyperbranched hydrodipolycarbosilane (PHPCS), was prepared by a modified synthesis route, which involved Grignard coupling of partially methoxylated Cl(3)SiCH(2)Cl and CH CCH(2)Cl, followed by reduction with lithium aluminum hydride. The resultant PHPCSs were characterized by gel permeation chromatography, Fourier transform infrared (FTIR) spectroscopy, and NMR. Moreover, the thermal properties of the PHPCSs were investigated by thermogravimetric analysis. The ceramic yield of PHPCS at 1400 degrees C was about 82.5%, which was about 10 wt % higher than that of hyperbranched hydrodipolycarbosilane without the substitution of propargyl groups. The PHPCS-derived ceramics were characterized by X-ray diffraction (XRD), FTIR spectroscopy, and elemental analysis. The XRD and FTIR results indicate that the heat treatment significantly influenced the evolution of crystalline beta-SiC. It can be convenient to get near-stoichiometric ceramics from PHPCS through the control of feed ratios of the starting materials. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 121: 3400-3406, 2011National Natural Science Foundation of China[50802079, 20925208