SYNTHESIS OF POLY(STYRENE-DIMETHYLSILOXANE) BLOCK-COPOLYMERS - INFLUENCE OF THE PHASE-SEPARATED MORPHOLOGIES ON THE THERMAL BEHAVIORS

Five polystyrene-poly(dimethylsiloxane) di- and triblock copolymers we re prepared by two different methods, a classical anionic polymerizati on and a cationic polymerization of styrene in the presence of a new m acromolecular initiator. Spherical, cylindrical, and lamellar phase-se parated morphologies were identified. Their sizes were measured by tra nsmission electron microscopy (TEM) on films obtained from bulk and so lvent-cast samples. DSC and TEM show that the phase-separated morpholo gies are strongly segregated with no long range ordering. The specific microphase surface area, obtained by TEM, is strongly correlated with the broadening of the polystyrene glass transition.