Photocontrolled radical polymerization for the synthesis of ultrahigh-molecular-weight polymers

Compared with conventional thermally initiated radical polymerization, photocontrolled radical polymerization offers mild, environmentally friendly reaction conditions, fast polymerization rates, high end-group fidelity and spatiotemporal control. Access to ultrahigh-molecular-weight (UHMW) polymers with precisely defined molecular weights, structures and topologies requires a high degree of living character with minimal side reactions and has been a longstanding challenge in polymer synthesis. The recent development of photocontrolled radical polymerization has enabled facile synthesis of UHMW polymers. Here we discuss methods for producing various UHMW polymers via photocontrolled radical polymerization, including photoiniferter reversible addition–fragmentation chain transfer (RAFT) polymerization, photoinduced electron/energy transfer–RAFT polymerization, photoenzymatic RAFT polymerization, photocontrolled atom transfer radical polymerization and photocontrolled organotellurium-mediated radical polymerization, followed by an overview of the applications of UHMW polymers as high-performance materials. Finally, we provide our future perspective for developments in this emerging field. Well-defined vinyl polymers with ultrahigh molecular weights are promising for use as high-performance materials and are now made increasingly accessible by photocontrolled radical polymerizations. This Review discusses the methods developed for the synthesis of such polymers and their potential applications.