SYNTHESIS, CHARACTERIZATION AND SUBSEQUEN T REACTIONS OF BRANCHED POLY(PHENYLCARBOSILANES)

The syntheses of a series of branched poly(phenylcarbosilanes) was ach ieved through the Wurtz analogous reaction of phenyltrichlorosilane, d iphenyldichlorosilane and dibromomethylene with sodium as the reducing agent. The oligomeric products obtained were characterized spectrosco pically and by elemental analysis. Furthermore, the average molecular weights and the ceramic residues were determined. The poly(phenylcarbo silane) 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 substitutio n reaction of IV with HCl under the catalytic influence of AlCl3. A fo llowing hydrogenation with LiAlH4 led to the poly(hydridocarbosilane). The modified compounds have been characterized by H-1, C-13 and Si-29 NMR, and IR spectroscopy, GPC, elemental analysis and ceramic weights .