Block copolymers

Abstract

Structures of block copolymers with incompatible polymer components under two extreme conditions, i.e., in dilute solution and in bulk were compared. It was found that the chain dimension of an AB diblock copolymer in dilute solution of a common good solvent is quite similar to that of a homopolymer with the same chain length, which means no segregation occurs in dilute solution. AB diblock and BAB triblock copolymers in microphase-separated bulk were confirmed to be shrunk in lateral direction of microdomain interface to compensate elongation in normal direction to the interface. Their interfacial thicknesses were measured to be fairly thin, it is comparable to A/B homopolymer interfacial thickness. Symmetrical three-component ABC triblock copolymers were found to form easily tricontinuous structure as one of the superlattice structures, while bicontinuous structure is not a stable structure for two-component copolymers.