Morphology and Properties of Styrene and Dimethylsiloxane Triblock and Multiblock Copolymers

Multiblock copolymers (BAB)n of styrene and polydimethylsiloxane were synthesized by coupling diphenyldiacetoxysilane with preformed triblock copolymers of siloxane—styrene—siloxane terminated with "living" silanolate ends. Electron microscopy and dynamic measurements were used to examine the phase separation of these copolymers. The dimethylsiloxane content, molecular weight, and polydispersity of these specimens were investigated also. A difference was noted in the tensile behavior of the multiblock copolymers obtained from solution-cast films. The results show that the morphology of the multiblock copolymers studied is defined only when films are cast from their preferential solvents. Characterization of the microdomain structures of these block copolymers revealed polystyrene discrete spheres dispersed in a rubbery polydimethylsiloxane matrix.