Functional Polyester Synthesis from CO2, Butadiene and Epoxides

Carbon dioxide (CO2), as a renewable, abundant and inexpensive C1 feedstock, has long been recognized as an ideal comonomer to prepare sustainable materials. Contrast to the well-established alternating copolymerization of CO2 and epoxides, little success has been made on polymer synthesis via CO2/olefin copolymerization. Here we report an unprecedented strategy to synthesize bifunctional polyesters from CO2, butadiene, and epoxides via a metastable lactone intermediate, 3-ethylidene-6-vinyltetrahydro-2H-pyran-2-one (EVP). The obtained polyesters with tunable EVP content (39-93 mol%) show good thermal stability, and can conveniently undergo chemical degradation. Mechanistic studies revealed that the in situ formation of dimer EVP circumvented the electronic effect of conjugated ester and enhanced the steric hindrance, promoting the desired ring-opening reaction. This method extends the potential to access functional CO2-based polymers beyond the conventional polycarbonates obtained from CO2 and epoxides.