Photoinduced controlled radical polymerization mediated by BiOCl nanosheets under simulated solar light

Abstract

Photochemically active bismuth oxychloride (BiOCl) nanosheets are evaluated for photoinduced controlled radical polymerization under simulated sunlight irradiation, demonstrating that BiOCl-mediated reversible addition fragmentation chain transfer (RAFT) polymerization is feasible. The benefit of using heterogeneous photocatalysts includes easy removal of the catalyst after polymerization. A variety of vinyl monomers including methyl acrylate, ethyl acrylate, N,N-dimethylacrylamide, oligo(ethylene glycol) methyl ether methacrylate, and 4-acryloylmorpholine are successfully polymerized in the presence of trithiocarbonate- and dithiobenzoate-based chain transfer agents at ambient temperature, affording polymers with Mn in the range of 3.8–52 kDa and polymer dispersities (Đ) of 1.11–1.26. Successful chain extension experiments further support that high-end-group fidelity is achieved during sunlight-driven BiOCl-mediated RAFT polymerization. In addition, temporal control is demonstrated through intermittent light and dark cycles, where a substantial polymer growth is observed exclusively under sunlight irradiation. BiOCl-mediated RAFT polymerization can also impart excellent control over controlled radical polymerization of water-soluble monomers in water without the need of degassing with nitrogen. Kinetic study of BiOCl-mediated RAFT polymerization of N,N-dimethylacrylamide shows that the apparent rate constants are comparable with and without degassing. This study showcases the utility of heterogeneous photocatalyst BiOCl nanosheets for RAFT polymerization.