SYNTHESIS OF POLYSILANE POLYMER PRECURSORS AND THEIR PYROLYSIS TO SILICON CARBIDES

Organosilane polymers of the type [R1R2Si]n were prepared by dechlorin ation of R1R2SiCl2 (R1 = CH3; R2 = H, C2H5, C3H7, C4H9, C6H11, C8H17 o r C6H5) with sodium in toluene as solvent. The polymers were character ized by i.r., NMR and thermal analysis. The decomposition temperature, yield, solubility, appearance were found to depend strongly on molecu lar structure. The pyrolysis of polymethylsilane was found to give a 6 0% ceramic yield after thermal processing at 750-degrees, suggesting i ts potential for use as a precursor to SiC ceramics.