MORPHOLOGIES AND DOMAIN SIZES OF MICROPHASE-SEPARATED STRUCTURES OF BLOCK AND GRAFT-COPOLYMERS OF DIFFERENT TYPES

Well-defined block and graft copolymers of different types with differ ent compositions and molecular weights, such as styrene(S)-2-vinylpyri dine(P) diblock copolymers, SP star-shaped block copolymers, PSP tribl ock copolymers, styrene(S)-isoprene(I) multiblock copolymers of the (S I)(n) type, ISP triblock copolymers, SPP graft copolymers and their de uterated samples were prepared. Variations of the morphologies with co mpositions, molecular weight dependences of the lamellar domain sizes and conformations and distributions of block chains in the lamellar do mains were studied in the strong segregation limit. Besides typical mo rphologies such as spherical, cylindrical and lamellar structures, ord ered bi- and tri-continuous structures were found between cylindrical and lamellar structures for SP diblock copolymers, PSP and ISP tribloc k copolymers, respectively. The composition ranges of morphologies are different for the block and graft copolymers of different types. The molecular weight dependences of lamellar domain sizes are about the sa me, but their magnitudes are not always the same for the block and gra ft copolymers of different types. These results are well explained by the theories of Helfand-Wasserman and Semenov. Block chains in lamella e are extended along the direction perpendicular to lamellae, but they are contracted along the parallel direction. The former result is wel l explained by the theories, but the latter is not. Chains adjacent to the junction points between different block chains are localized near the domain interface, but chains at the free-ends of block chains are widely distributed in the domain with the maximum at the center of do main.