Study on syntheses and characterizations of polymethylphenethylsilane, polymethylcyclohexylsilane and their copolymers

The effects of adding cosolvents of diglyme and 15-crown-5 to the reaction mixture of Wurtz-type coupling of dichlorosilanes on the yield and relative molecular mass dispersity of polymethylphenethylsilane(PMPES) were discussed. The results show that addition of 10% (volume ratio of diglyme to toluene) diglyme as a cosolvent to the reaction mixture leads to the yield increase of PMPES with a monomodal distribution of relative molecular masses. Adding 10% diglyme to the reaction mixtures, the yields of polymethylcyclohexylsilane(PMCS) and copolymers (polymethylphenethylsilane-co-methylcyclohexylsilane), (the molar ratios of methylphenethyldichlorosilane to methylcyclohexyldichlorosilane were 2.0, 1.0 and 0.5, and the copolymers were abbreviated by Copolymers I, II, III, respectively) are 47%, 52%, 54%, 53%, respectively. Their relative molecular masses almost reach 10⁵. These polysilanes were characterized by ¹H-NMR, IR and UV absorption spectrum. Foundation item: The National Natural Science Foundation of China (No. 28970817) Biography of the first author: HU Hui-ping, doctoral student, born in 1969, majoring in applied chemistry.