Abstract
We have synthesized and characterized rod−coil diblock, triblock, and starblock copolymers of controlled molecular weight by stable free radical polymerization, where the rod part consists of “mesogen jacketed liquid crystalline segments” (MJLCP). The MJLCP segment examined in our studies is poly{2,5-(4-butylbenzoyl)oxystyrene} (PBBOS) while the coil part is poly(styrene). SAXS studies of the block copolymers at room temperature predominantly show only a first-order maximum in their SAXS spectra. Above the Tg of the two blocks (∼150 °C) no phase-separated morphology could be detected in temperature-dependent SAXS measurements of the block copolymers. Slow cooling regenerates the morphology, indicating very slow ordering kinetics. The effects of variation in molecular architecture and increasing topological constraint in going from homopolymer to star block copolymer on melt rheology (i.e., viscosity, relaxation times, and activation energies) are reported. In the master curves of all the block copolymers ...
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