Accessing Divergent Main-Chain-Functionalized Polyethylenes via Copolymerization of Ethylene with a CO₂/Butadiene-Derived Lactone

Carbon dioxide (CO2) has been used as a sustainable comonomer in the synthesis of different functional polymers including polycarbonates, polyurea, and polyurethane. Until today, despite the great interest, little success has been made for incorporating CO2 into the most widely used polyethylene materials. Herein, we report the incorporation of CO2 to polyethylenes through the copolymerization of ethylene with a CO2/butadiene-derived lactone, 3-ethylidene-6-vinyltetrahydro-2H-pyran-2-one (EVP). Two-types of main-chain-functionalized polyethylenes can be synthesized through different copolymerization strategies. Palladium-catalyzed coordination/insertion copolymerization furnished polyethylenes bearing unsaturated lactones, while radical copolymerization afforded polyethylenes bearing bicyclic lactones. Modification of the polyethylene chains was successfully accomplished through Michael addition or aminolysis. This highly versatile copolymerization protocol provides access to a diverse range of polyethylene materials made from ethylene, CO2, and 1,3-butadiene.