Macro-RAFT agent mediated dispersion copolymerization: a small amount of solvophilic co-monomer leads to a great change

Abstract

The macro-RAFT agent mediated dispersion copolymerization of two monomers, in which one is hydrophobic and the other is hydrophilic, is proposed to conveniently tune the morphology of the in situ synthesized block copolymer nano-objects. The poly(ethylene glycol) trithiocarbonate macro-RAFT agent mediated dispersion copolymerization of styrene and 4-vinylpyridine (St/4VP) in alcoholic solvent affords the in situ synthesis of the diblock copolymer nano-objects of poly(ethylene glycol)-block-poly(4-vinylpyridine-co-styrene) [PEG-b-P(4VP-co-St)]. It is found that, the morphology of the PEG-b-P(4VP-co-St) diblock copolymer nano-objects can be easily tuned either by changing the polymerization degree of the random P(4VP-co-St) block or the molar ratio of the PS/P4VP segments in the random P(4VP-co-St) block. The poly(ethylene glycol) trithiocarbonate macro-RAFT agent mediated dispersion copolymerization of St/4VP is compared with the dispersion RAFT polymerization of St, and the advantage of the dispersion RAFT copolymerization in tuning the block copolymer morphology is demonstrated. Our study is believed to be a promising extension of the polymerization induced self-assembly (PISA) under dispersion RAFT polymerization.