SYNTHESIS OF REACTIVE POLYSILOXANES HAVING PRESCRIBED MOLECULAR WEIGHT BY CONDENSATION OF CHLOROSILANES

Abstract

Hydrolysis and the following polycondensation of chloroslanes were studied to elucidate the reaction conditions for the synthesis of reactive polysisiloxanes having prscribed molecular weights. The hydrolysis of chlorosilanes proceeded very rapidly as shown by the determination of evolved HiCl gas, which was followed by the polycondensation of silanol groups produced by the initial hydrolysis. GPC measurements on the resulted polysiloxanes revealed that the dilution of dichlorosilanes and the concentration of monochlorosilanes as end-blockers were effective to control the molecular weight of polysiloxanes. As cohydrolysis and co-condensation systems, dichloromethylvinylsilane (MVSi)/chlorodimethylvinysilsilane (DMVSi), dichlorodimethylsilane (DMSi)/chlorodimethylvinylsilane (DMVSi) and DMSi/dichlorocyanopropylmethylsilane (CPMSi) systems were investigated and the results were all positive for the purpose of molecular weight control. In the third system, the cyano groups were converted to carboxylic groups and polysiloxane having carboxylic groups and a prescribed molecular weight was resulted