Commodity Polymer Functionalization by a Combination of Hydrogen Atom Transfer Reversible Addition-Fragmentation Chain Transfer Polymerization and Pentafluorophenyl-Ester-Ligation Chemistry.

Development of highly efficient and versatile strategies for functionalization of commodity polymers direct from carbon-hydrogen (C-H) bonds has attracted growing interest due to the ubiquity of C-H bonds in various commodity polymers and the great desire for upcycle of commodity polymers. However, the efficiency of C-H activation is usually low (<20%) and only one (potential) functional unit was introduced into each activated C-H bond. The low content of introduced functional units could be one great hindrance to the improvement of performance of resulting polymers. Herein we report a photocatalytic hydrogen atom transfer reversible addition-fragmentation chain transfer (HAT-RAFT) grafting polymerization strategy to introduce polymeric side chains of activated pentafluorophenyl esters (PFEs) into commodity polymers of poly(ethylene glycol), poly(propylene oxide), polybutylene, polypropylene, and poly(vinylpyrrolidone) by using the C-H bonds of commodity polymers as the initiating sites. The grafting polymerization of pentafluorophenyl acrylate (PFA) exhibits living/controlled features and temporal controllability. With the amplification effect of grafting polymerization, each activated C-H bond allows to the introduction of tens of PFEs, leading to a high content of PFE groups. Owing to the high reactivity of PFEs toward amino- and hydroxyl-containing molecules under mild conditions with excellent efficiency and group tolerance, the introduced PFEs of PPFA chains enable quantitative transesterification and amidation for efficient functionalization of commodity polymers via PFE-ligation chemistry.