Binary-component micelle and vesicle: Free energy and asymmetric distributions of amphiphiles between vesicle monolayers

Abstract

The real-space two-dimensional self-consistent field theory (SCFT) is employed to study the free energies of micelles and vesicles constituted by binary amphiphilic diblock copolymer AB in homopolymer A. With an increasing volume fraction of copolymer AB, there are morphological transitions from circle micelles to oblate circle-like micelles, to a compound structure with inverted micelles in the inner center and micelles outer layer, and to vesicles. Special attention is paid to the role of the copolymer AB in controlling the free energies of the micelles and vesicles by examining the effect of the length ratio of A/B with the fixed whole chain length of the AB copolymer, the length effect of A or B block with the corresponding fixed length of B or A block, for one component of copolymer, and the effect of different amphiphile compositions for a binary-component copolymer system. The quantity η is provided to describe the asymmetric density distribution of amphiphiles between the inner and outer monolayers of vesicles, and to quantify the relative asymmetric extent of the density distribution between two species of copolymers in binary component vesicles.