THERMALLY AND OXIDATIVELY STABLE THERMOSETS DERIVED FROM PRECERAMIC MONOMERS

Monomers ,3-bis(4-phenylethynylphenyl)tetramethyldisiloxane and henyle thynylphenyltetramethyldisiloxy)-m-carborane were synthesized and comp ared with bis(4-phenylethynylphenyl)dimethylsilane as potential precer amic precursors. These monomers were heated to free flowing liquids ab ove 100 degrees C and thermally polymerized above 300 degrees C to for m heat-resistant thermosets or ceramic residues. The ceramic yields fo r the silane (13%) and siloxane (30%) were much lower than that for th e carborane (64%) monomer. The thermoset and ceramic made from the car borane monomer were the best thermally and oxidatively stable material s. After curing, the thermoset had a weight loss of only 6% and after pyrolysis, the ceramic residue had no additional weight loss up to 100 0 degrees C in air. (C) 1997 John Wiley & Sons, Inc.