Postpolymerization of Poly(ethylene oxide) through C–H Functionalization

This paper describes a novel method for directly modifying poly(ethylene oxide) (PEO) by attaching functional groups using C-H bond functionalization. While existing methods for PEO modification, such as copolymerization and PEGylation, have limitations, direct functionalization of PEO has been challenging due to the difficulty in finding versatile polymerization conditions that can accommodate various functional epoxides. This study demonstrates a fully organocatalytic approach for direct PEO functionalization with carboxylic acids, resulting in a broad substrate scope that includes aromatic, aliphatic, and biologically active carboxylic acids such as ibuprofen and glycyrrhetinic acid. Importantly, our condition preserves the parent PEO structure throughout the highly reactive radical and oxocarbenium intermediate.