Combining Green Light-Activated Photoiniferter RAFT Polymerization and RAFT Dispersion Polymerization for Graft Copolymer Assemblies

Although reversible addition–fragmentation chain transfer (RAFT) dispersion polymerization-induced self-assembly (PISA) has become one of the most attractive methods for the synthesis block copolymer assemblies, the synthesis of well-defined graft copolymer assemblies has rarely been reported. Herein, multifunctional macro-RAFT agents with well-defined structures were synthesized by green light-activated photoiniferter RAFT polymerization and subsequently used in RAFT dispersion polymerization for the synthesis of graft copolymers as well as graft copolymer assemblies. A direct comparison between RAFT-PISA behaviors of linear block copolymers and graft copolymers was conducted by using a monofunctional macro-RAFT agent and a multifunctional macro-RAFT agent, respectively. Transmission electron microscopy (TEM) analysis demonstrated that the structure of graft copolymers facilitated the creation of polymer nanoparticles with higher-order morphologies. Multifunctional macro-RAFT agents with different distributions of RAFT groups were also synthesized via a two-step photoiniferter RAFT polymerization. The influence of the distribution of solvophobic side chains on the RAFT-PISA process as well as graft copolymer assemblies was also investigated. We anticipate that this work should not only shed some light on the synthesis of well-defined graft copolymers and graft copolymer assemblies but also be useful to understand the mechanism RAFT-PISA of graft copolymers.