Photoinduced Flow Cationic RAFT Polymerization Using Diphenyliodonium Salt as Photoacid Generator

ABSTRACT

Living cationic polymerization (LCP) under mild and scalable conditions remains a longstanding challenge due to the intrinsic sensitivity of cationic species. Herein, we report a metal‐free, visible‐light‐induced cationic reversible addition–fragmentation chain transfer (RAFT) polymerization of vinyl ethers in a continuous‐flow microreactor using diphenyliodonium hexafluorophosphate (DPI) as a commercially available photoacid generator (PAG). The integration of photochemistry with flow processing enables precise control over polymerization at room temperature without rigorous reagent purification or an inert atmosphere. The system affords polymers with predictable molecular weights, narrow molecular weight distributions, and excellent end‐group fidelity, as evidenced by kinetic analysis and successful block copolymerization. The enhanced mass, heat, and photon transfer in the microreactor effectively mitigates local heat accumulation and ensure uniform irradiation, overcoming key limitations of batch processes. Furthermore, a broad range of vinyl ether monomers can be polymerized in a controlled manner, and copolymerization allows tunable thermal properties. This work establishes a robust and scalable platform for controlled cationic polymerization, offering new opportunities for the development of metal‐free photopolymerization technologies in continuous flow.