Synthesis and chemical modification of poly(divinylsiloxane)

Hexavinylcyclotrisiloxane(I) has been prepared by reaction of divinyldichlorosilane with DMSO and triethylamine. Anionic ring-opening polymerization (AROP) of I catalyzed by dilithio diphenylsilanediolate yields high molecular weight poly(divinylsiloxane)(II) with a narrow molecular weight distribution. Similarly, narrow molecular weight distribution poly(vinylmethylsiloxane)(III) has been prepared by AROP of 1,3,5-trimethyl-1,3,5-trivinylcyclotrisiloxane(IV) initiated by dilithio diphenylsilanediolate. On the other hand, III which has a broad molecular weight distribution has been synthesized by AROP of 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane(V) catalyzed by phosphazene P4-t-Bu superbase. Chemical modification of the C–C double bonds of II and III has been achieved by Pt-catalyzed hydrosilylation with 3,3,3-trifluoropropyldimethylsilane(VI) or 1H,1H,2H,2H-perfluorooctyldimethylsilane(VII). While Pt-catalyzed hydrosilylation reactions usually proceed in a regioselective anti-Markovnikov manner, Markovnikov addition is competitive in these examples.