Precise evaluation of the block copolymer nanoparticle growth in polymerization-induced self-assembly under dispersion conditions

Polymerization-induced self-assembly is demonstrated to be a valid strategy to prepare highly concentrated block copolymer nano-objects. Herein, an investigation on the growth of block copolymer nanoparticles through macro-RAFT agent-mediated dispersion polymerization was performed by employing the brush macro-RAFT agent poly[poly(ethylene oxide) methyl ether vinylphenyl] trithiocarbonate (PmPEGV-TTC) and the linear poly(dimethylacrylamide) trithiocarbonate (PDMA-TTC) as typical examples. Well-controlled dispersion RAFT polymerization employing either the brush or linear macro-RAFT agent was achieved, and uniform block copolymer nanoparticles were obtained. A decreasing number of block copolymer nanoparticles (Np) in the polymerization medium and an increasing aggregation number (Nagg) of the block copolymer nanoparticles during the nanoparticle growth were detected, and both particle-disassembly/reassembly and chain extension of the block copolymer contributing to the growth of the block copolymer nanoparticles were concluded. The present study is anticipated to be helpful to clarify the growth of block copolymer nanoparticles via polymerization-induced self-assembly under dispersion conditions.