POLYMERIC ORGANOSILICON SYSTEMS .25. PREPARATION OF BRANCHED POLYMERSBY REGIOSPECIFIC HYDROSILYLATION OF POLY[(SILYLENE)DIETHYNYLENES] ANDTHEIR PROPERTIES

Regiospecific 1,2-hydrosilylation reactions of (dimethylsilylene)-, (m ethylphenylsilylene)-, and (diethylsilylene)diethynylene polymers with 1,4-bis(methylphenylsilyl)benzene in the presence of a catalytic amou nt of Rh-6(CO)(16) afforded the respective branched polymers with high molecular weights in high yields. The rate of the hydrosilylation and degree of branching were found to be affected by polarity of the solv ent, amounts of the catalyst, reaction temperature, and concentration of the polymers. It was found that degradation of the resulting branch ed polymers and also starting polymers readily took place when they we re treated with ethanol in the presence of triphenylphosphine. The rea ction of poly-[(tetramethyldisilanylene)diethynylene] with hydrosilane s in the presence of the rhodium-(0) catalyst proceeded to give hydros ilylation products, but scission of the polymer chain was also observe d. A mechanism for the degradation of polymers is discussed on the bas is of the results obtained for model compounds.