Sequential Radical-Anionic Polymerizations via Consecutive Photo-Reduction

Polymeric properties are intimately entwined with the diversities of structures, making the development of polymerization methods highly valuable to both academic research and industrial applications. Although radical and anionic polymerization techniques have been widely used, both currently have intrinsic limitations. For example, anionic polymerizations heavily rely on highly reactive alkyl metals and alkali metals (e.g., lithium), which involve energy-intensive synthesis and hazardous handling. Herein, we report a sequential radical-anionic (co-)polymerization, where the in situ generation of carbon radicals and carbanions via photoreduction enables augmentation of the monomer repertoire. This approach eliminates lithium dependency and its associated resource, energy, and safety concerns. Mechanistic studies support the sequential radical-anionic chain-growing mechanism enabled by photo-induced consecutive single-electron transfer reduction. This strategy has the potential to overcome the intrinsic restriction in copolymerizing monomers with electronic property disparities, thereby extending the synthetic utilization of anionic polymerization in polymer science. Furthermore, the process and vulcanization of large-scale synthesized terminal-functionalized rubbers further prove the practical applications of this strategy.