Asymmetrical vesicles: convenient in situ RAFT synthesis and controllable structure determination

Asymmetrical vesicles constructed with two diblock copolymers of poly(ethylene glycol)-b-polystyrene (PEG-b-PS) and poly(4-vinylpyridine)-b-polystyrene (P4VP-b-PS) were prepared through the in situ synthesis strategy of the two macro-RAFT agents co-mediated dispersion polymerization. The structure of the PEG-b-PS/P4VP-b-PS asymmetrical vesicles was found to be dependent on the degree of polymerization (DP) of the poly(ethylene glycol) (PEG) and poly(4-vinylpyridine) (P4VP) blocks. In the case of the DP of the P4VP block being smaller, slightly larger, and much larger than the DP of the PEG block, the P4VP chains were located at the inner sides of the vesicle wall, located at both the outer and inner sides of the vesicle wall, and located at the outer side of the vesicle wall, respectively. The proposed two macro-RAFT agents co-mediated dispersion polymerization affords great convenience in the synthesis of asymmetrical vesicles with a well-defined structure, and it is also very helpful to understand the correlation between the block copolymer composition and the structure of asymmetrical vesicles.