Sunlight-driven Photoinduced Electron/Energy Transfer-Reversible Addition-Fragmentation Chain Transfer Polymerization at Large Scale

Abstract

Photoinduced electron/energy transfer-reversible addition-fragmentation chain transfer (PET-RAFT) polymerization is a sustainable and powerful tool to synthesize polymers and copolymers. However, 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 heterogeneous photocatalyst for efficient PET-RAFT polymerization. This development allowed PET-RAFTs 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 an obvious structural deterioration and decrease in efficiency. Sunlight-driven photopolymerization of MA (methyl acrylate) was scaled up to 2 L (conversion 93%), and the obtained polymer showed good control over both molecular weight and dispersity (Đ = 1.13). White light driven polymerization of MA (conversion 91%, Đ = 1.27) reached 6 L scale. These results demonstrate the great potential for industrial applications.