Morphology and Miscibility of Miktoarm Styrene-Diene Copolymers and Terpolymers

The microphase separation of the new miktoarm styrene—diene polymers has been examined. At the molecular weights studied, the PS arms always separate from the polydienes, but the PI and PB arms mix when they occur in the same molecule. This is the kind of behavior that would be expected from experience with linear diblocks. On the other hand, the miktoarm architecture does seem to strongly affect the kind of microphase-separated domains that are formed in these polymers. The polymers with a single PS arm and two polydiene arms formed PS cylinders, whereas a lamellar or bicontinuous structure would have been expected from literature on linear block polymers. This appears to be due to effects of the miktoarm structure on the curvature energy of the interface.