Site-Controlled Incorporation of a Single Degradable Junction in RAFT Polymers for Tailored Block and Graft Copolymers

The precise installation of cleavable junctions at defined positions within synthetic polymers remains a significant challenge, limiting the development of materials with degradation profiles akin to natural biopolymers. Herein, we report a novel strategy using reversible addition–fragmentation chain-transfer (RAFT) polymerization to insert a single 5,6-benzo-2-methylene-1,3-dioxepane (BMDO) unit precisely at the junction points of block and graft copolymers via a single-unit monomer insertion (SUMI) approach. This single ester-containing linkage enables selective cleavage, allowing efficient dissociation of block copolymers into their constituent blocks and detachment of grafts from molecular brush backbones. Our method transforms degradation from a non-specific process into a targeted, junction-specific event, providing a modular platform for the design of smart materials with triggered dissociation capabilities for potential applications in degradable surfactants, responsive coatings, and delivery systems.