Closed-Loop and Precision Synthesis of Polymuconates via Organocatalyzed Group Transfer Polymerization

We report a highly controlled, metal-free polymerization platform for the synthesis and closed-loop recycling of biobased polymuconates, overcoming longstanding limitations in group transfer polymerization (GTP) of conjugated dienes. Using a mild organocatalytic system based on P₂-<i>t</i>-Bu in tetrahydrofuran as a solvent, and initiated by 1-ethoxy-1-(trimethylsiloxy)-1,3-butadiene (ETSB), our method enables rapid polymerization (<10 min, room temperature) with excellent control both over molar mass and dispersity (Đ ≤ 1.2) and predictable polymuconate chain lengths. Mechanistic investigations support a dissociative GTP pathway involving 1,6-conjugate addition reactions with dynamic exchange between dormant and propagating species, ensuring uniform chain growth and suppressing side reactions. This strategy extends to all three stereoisomers of muconate esters, including the biobased cis,cis and cis,trans forms, broadening the scope of monomers compatible with GTP. We further demonstrate the living character of this polymerization through successful chain extensions and the synthesis of structurally well-defined muconate-based block copolymers. Importantly, these materials can be thermally depolymerized to recover pure monomers, which are amenable to repolymerization under identical conditions, thus enabling a true closed-loop chemical recycling process. Our work provides a scalable, sustainable route to precision-engineered, degradable polar polydienes, representing a potential alternative to conventional vinyl polymers.