A3B-type miktoarm star polymer nanoassemblies prepared by reversible addition–fragmentation chain transfer (RAFT) dispersion polymerization

Abstract

The construction of new macromolecular architecture is an effective route to obtain diverse self-assembled morphologies in polymerization-induced self-assembly (PISA). Herein, four macro-chain transfer agents (macro-CTAs) bearing three methoxy polyethylene glycol (mPEG) arms of increasing length were synthesized for the first time with great precision, and used in the RAFT mediated dispersion polymerization of styrene (St). The well-controlled polymerization of St was attained, yielding A₃B-type miktoarm star (mPEG)₃-PS nanoassemblies. A parallel comparison between the nanoassemblies of (mPEG750)₃-PS and linear mPEG2000-b-PS indicated the remarkable effect of A₃B architecture in delaying the micelle-worm and worm-vesicle transitions and promoting the formation of larger vesicles. In addition, unusual morphologies such as oversized vesicle, columnar vesicle and multi-lamellar vesicle were formed for (mPEG550)₃-PS nanoassemblies.