Poly(α‐methylstyrene)–poly(dimethylsiloxane) block copolymers

Block copolymers were synthesized by the condensation of dihydroxyl‐terminated poly‐(α‐methylstyrene) oligomers and bisdimethylamino‐terminated poly(dimethylsiloxane) oligomers. Manipulation of block molecular weight produced copolymers ranging in composition from 21% to 73% poly(dimethylsiloxane). Compression moldablity was found to be good. Physical properties were dependent upon siloxane content, varying from high modulus, low elongation to low modulus, high elongation materials. High siloxane‐content compositions exhibited elastomeric properties due to the two‐phase morphology of these systems. Glass transition temperatures were observed as low as −120°C for the poly(dimethylsiloxane) block and as high as + 140°C for the poly(α‐methylstyrene) block. Even higher poly(α‐methylstyrene) transition temperatures may be possible by using higher molecular weight oligomers.