Sunlight-driven photoinduced electron/energy transfer-reversible addition-fragmentation chain transfer polymerization at a large scale

Photoinduced electron/energy transfer-reversible addition-fragmentation chain transfer (PET-RAFT) polymerization is a sustainable and powerful tool to synthesize polymers and copolymers. However, the development of large-scale production and polymerizations using sunlight irradiation remain top challenges for PET-RAFT polymerizations. In this study, conjugated cross-linked phosphine (PPh₃-CHCP) was explored as a heterogeneous photocatalyst for efficient PET-RAFT polymerization. This development allowed PET-RAFT processes to achieve high monomer conversions, low dispersity and good chain-end fidelity under a broad range of wavelengths and sunlight irradiation from various monomers. The heterogeneous PPh₃-CHCP photocatalyst could be easily separated and reused without obvious structural deterioration or decrease in efficiency. Sunlight-driven photopolymerization of MA (methyl acrylate) was scaled up to 2 L (conversion of 93%), and the obtained polymer showed good control over both molecular weight and dispersity (<i>Đ</i> = 1.13). White light-driven polymerization of MA (conversion of 91%, <i>Đ</i> = 1.27) reached a 6 L scale. These results demonstrate a great potential for industrial applications.