Laves Phases in Block Copolymer-Homopolymer Blends

Recently, new Frank-Kasper phases, e.g. C14 and C15 Laves phases, have been observed in specific conformation-asymmetric AB diblock copolymers via a special thermal process by expeiments. Surprisingly, the two Laves phases have been predicted to be stable in binary blends of conformtion-symmetric AB diblock copolymers by theory. In this presentation, we investigate the self-assembly of binary blends of conformtion-asymmetric AB-type block copolymer and A homopolymer, where the minority A-component forms the spherical domains, using the self-consistent field theory (SCFT). With three typical block copolymer systems, forming face-centered cubic, sigma and A15 phases, respectively, the addition of A-homopolymer leads to the formation of stable C14 and C15 phases. Our SCFT calculations reveals that the C14 and C15 phases are stabilized by the unequal contents of A-homopolymer among spherical domains that facilitate the formation of highly nonuniform sizes of domains. This work provides another simple facile way to fabricate the novel Frank-Kasper phases.