α‐Methylene‐δ‐Valerolactone as a Bioderived Comonomer for RAFT and PhotoATRP

We report the reversible deactivation radical copolymerization of bioderived α‐methylene‐δ‐valerolactone (MVL) with methacrylate, styrenic, and acrylate comonomers using reversible addition–fragmentation chain transfer (RAFT) and photo‐induced atom transfer radical polymerization (photoATRP). Under optimized conditions, MVL was incorporated preferentially relative to the comonomer, giving well‐defined copolymers across a broad molecular‐weight range with low dispersity and enabling block‐copolymer synthesis by chain extension. Increasing MVL incorporation increased glass transition temperature across all monomers studied, consistent with the rigid pendant lactone unit. These results establish MVL as a practical bio‐derived comonomer for reversible deactivation radical polymerization and as a route to functional vinyl copolymers with enhanced thermal performance.