Catalytic Syntheses of Degradable Polymers Via Ring-Opening Metathesis Copolymerization Using Vinyl Ethers As Chain Transfer Agents

Commercially available Vince lactam and its deriva-tives are copolymerized with 2,3-dihydrofuran (DHF) in a living fashion based on the unique reactivity of Ru Fischer carbene. The resulting copolymers can be fully degraded into small molecules under mildly acidic conditions, suggesting a uniform incorporation of the DHF units throughout the polymer backbone. The regioselective and ultrafast chain transfer of G3-benzylidene to vinyl ethers enabled us to synthesize a narrowly dispersed triblock copolymer via macroinitiation from poly(ethylene glycol) divinyl ether. This high metathesis activity and regioselectivity of vinyl ethers was further exploited in a kinetically controlled catalytic synthesis of degradable copolymers using vinyl ethers as effective chain transfer agents. This strategy paves the way for a one-pot synthesis of degradable ROMP polymers from easily accessible monomers and chain transfer agents. We report a catalytic copolymerization in which up to 500-fold savings in the expensive and toxic ruthenium carbene complex can be achieved compared to a conventional ROMP. We believe that this cost-effective and environmentally friendly synthesis of degradable polymers will be highly useful for many biomedical applications as well as for environmental sustainability.