Preparation of ABA triblock copolymer assemblies through “one-pot” RAFT PISA

The morphologies and sizes of PDMAc-b-PSt-b-PDMAc amphiphilic triblock copolymers were controlled effectively by RAFT PISA with bi-functional PDMAc-TTC-PDMAc macro-CTA. [Display omitted] Poly(N,N-dimethyl acrylamide)-block-poly(styrene)-block-poly(N,N-dimethyl acrylamide) (PDMAc-b-PSt-b-PDMAc) amphiphilic triblock copolymer micro/nano-objects were synthesized through reversible addition-fragmentation chain transfer (RAFT) dispersion polymerization of St mediated with poly(N,N-dimethyl acrylamide) trithiocarbonate (PDMAc-TTC-PDMAc) bi-functional macromolecular RAFT agent. It is found that the morphology of the PDMAc-b-PSt-b-PDMAc copolymer micro/nano-objects like spheres, vesicles and vesicle with hexagonally packed hollow hoops (HHHs) wall can be tuned by changing the solvent composition. In addition, vesicles with two sizes (600 nm, 264 nm) and vesicles with HHHs features were also synthesized in high solid content systems (30 wt% and 40 wt%, respectively). Besides, as compared with typical AB diblock copolymers (A is the solvophilic, stabilizer block, and B is the solvophobic block), ABA triblock copolymers tend to form higher order morphologies, such as vesicles, under similar conditions. The finding of this study provides a new and robust approach to prepare block copolymer vesicles and other higher order micelles with special structure via PISA.