Facile synthetic route of polycarbosilane as a SiC precursor with zeolite catalysts

Polycarbosilane (PCS), a well known preceramic polymer which is frequently used as an SiC precursor, was synthesized from the thermal decomposition of polydimethylsilane (PDMS) in the presence of various types of zeolites as catalysts. The PDMS with different types and amounts of the zeolite catalysts was heated at 350 degrees C for 6 h, followed by heating at 400 degrees C for an additional 6 h in an autoclave. The use of the zeolite catalysts allowed the PCS to be synthesized under milder conditions and with a higher efficiency than those observed in the Yajima process, by accelerating the thermal decomposition of the PDMS. The PCS product was separated into three fractions, viz. the insoluble fraction, the solid and soluble fraction, and the low molecular weight liquid product. The solid and soluble PCS was characterized by TGA, FT-IR, GPC and NMR analysis, in order to study the effect of the catalysts on the chemical properties of the polymer.