LOCAL MOTIONS IN A MICROPHASE-SEPARATED POLY(STYRENE-B-METHYLPHENYLSILOXANE) DIBLOCK COPOLYMER MELT

The segmental dynamics in the microregions of a microphase-segregated poly(styrene-b-methylphenylsiloxane) (P(S-b-MPS)) with M(n) = 59.000 and PS fraction f(PS) = 0.22 were selectively studied by depolarized light scattering and dielectric spectroscopy over the temperature range -2O to + 110-degrees-C. About 50% of the material was found to partition in PS-rich and PMPS-rich environments with orientational dynamics very similar to that of the pure homopolymers. Below the high glass transition temperature, the segmental relaxation within the PS microregion displays a weaker temperature dependence and the relaxation distribution function becomes narrower, as compared to those of PS homopolymer.