Expanding Radical Initiation to Arenes in Photocontrolled Reversible Addition−Fragmentation Chain-Transfer Polymerization via Aryl Sulfonium Chemistry

Photoinduced RAFT polymerization enables spatiotemporal control of chain growth from native functional groups, yet current methods rely almost on alkyl radical precursors, restricting access to complex arene‑derived polymer conjugates. Here we introduce a photocontrolled RAFT strategy that leverages aryl sulfonium salts—prepared through site‑selective C–H functionalization—as aryl‑radical initiators. This approach enables controlled RAFT polymerization directly from diverse arenes, affording predictable molecular weights and narrow dispersities. The method expands the initiation chemistry of photocontrolled RAFT and provides a broadly applicable platform for constructing various arene drug/bioactive molecular/natural product–polymer conjugates.