Microstructures of emulsified polymer blends

Morphologies of solvent‐cast blends of immiscible polymer pairs emulsified with block copolymers have been examined using transmission electron microscopy. The morphology of such blends is controlled by the delicate balance in the swelling of each block copolymer segment by the corresponding compatible homopolymers. By manipulating the relative swelling via changes in molecular weight and enthalpic interactions, a variety of morphologies including macrophase co‐existing with microphase, and microphase alone, with structures ranging from spheres to vesicles, vesicles co‐existing with worm‐like microdomains, and phase‐inverted networks (PIN), are observed. The morphologies of ternary blends of the type A/A‐b‐B/B and A/X‐b‐B/B can be related to the phase behavior observed in the binary A/A‐b‐B and A/X‐b‐B blends.