Synthesis and pyrolysis of oligo(methylsilylene)-ethynylene polymer to near-stoichiometric SiC ceram

Oligo(methylsilylene)-ethynylene polymer with erosslinkable ethynyl unit in the main chain was synthesized by condensation of α,ω-dicholorooligo(methylsilane)with dilithioacetylene.The as-synthesized polymer was characterized by GPC,FT-IR and NMR.The results showed ethynyl group was successfully introduced to the polymer main chain.The ceramic yield was dramatically increased by the cross-polymerization of ethynyl group,and the excess silicon of PMS was compensated.Nearstoichiometric(C/Si = 1.17)and partial crystallization β-SiC monoliths were obtained by pressureless pyrolysing PSPA at 1200 ℃in a high yield(73.6 wt%).