NEW POLY(CARBOSILANE) MODELS .5. PYROLYSIS OF A SERIES OF FUNCTIONAL POLY(CARBOSILANES)

Ten models of functional poly(carbosilane) (PCS) or poly(carbosilazane) (PCSZ) precursors, prepared from chlorinated poly[(dimethylsilylene)methylene], were pyrolyzed, under inert gas flow or vacuum at temperatures up to 2300-degrees-C, to derive relations between the nature of the precursors and that of the ceramic residues. The organometallic/inorganic transition and the recrystallization of the pyrolytic residues were studied by different analytical techniques. Linear precursors resulted in low ceramic yields unless a cross-linking treatment was applied prior to pyrolysis. High C content precursors do not necessarily lead to high C content ceramics. Ternary (Si-C-O or Si-C-N) and even quaternary tetrahedral species were present in the ceramic residues. Nitrogen was found to inhibit the crystallization of the ex-PCSZ ceramics up to approximately 1400-degrees-C. Only part of the initial skeleton of the precursors was maintained in the ceramics.