Studies on equilibrium structures of complex polymers in condensed systems

Abstract

The thermodynamic-equilibrium structures of four copolymers with different chain architectures are compared. They are AB diblock, BAB triblock, and ABC triblock copolymers and AB2 star-branched graft copolymers. Their morphological transitions meaningfully differ from one another, reflecting the difference in chain architecture. Two-component polymers barely form bicontinuous structures; however, symmetric ABC triblock copolymers easily form tricontinuous structures composed of two surfaces parallel to a Gyroid minimal surface. All four ABC equilibrium structures have a superlattice structure. Block polymer chains in microphase-separated bulk are elongated in the longitudinal direction in lamellar microphases. Although the deformation manner of the chains restricted in microphases depends on the chain architectures, the volumes of the deformed coils are always the same as those of the unperturbed chains regardless of their architectures. The measured polystyrene/poly(2-vinylpyridine) interfacial thickness is fairly thin, but the observed value is much thicker than the theoretically predicted one. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1645–1655, 2000