Synthese, charakterisierung und folgereaktionen von verzweigten poly(phenylcarbosilanen)

The syntheses of a series of branched poly(phenylcarbosilanes) was achieved through the Wurtz analogous reaction of phenyltrichlorosilane, diphenyldichlorosilane and dibromomethylene with sodium as the reducing agent. The oligomeric products obtained were characterized spectroscopically and by elemental analysis. Furthermore, the average molecular weights and the ceramic residues were determined. The poly(phenylcarbosilane) of the composition [(SiPh2)1,5SiPh(CH2)3] x, (IV) was used as a binding agent in the production of pressurelessly sintered SiC-bodies (SSiC). The material properties like density, Young's modulus, Weibull modulus and 4-point bend strength were determined. The synthesis of a branched poly(chlorocarbosilane) was afforded through the substitution reaction of IV with HCl under the catalytic influence of AlCl3. A following hydrogenation with LiAlH4 led to the poly(hydridocarbosilane). The modified compounds have been characterized by 1H, 13C and 29Si NMR, and IR spectroscopy, GPC, elemental analysis and ceramic weights.