Chemoselective ring-opening copolymerization of δ-lactone derived from CO2 and butadiene via transesterification to synthesize bifunctional copolyesters†

Carbon dioxide (CO₂) is a versatile and sustainable resource for producing valuable chemicals. The telomerization of CO₂ with 1,3-butadiene affords 3-ethylidene-6-vinyltetrahydro-2H-pyran-2-one (EVP), an α,β-unsaturated cyclic ester and a compelling candidate for various polymerizations. However, chemoselective ROP of EVP is limited because of low conversion and the need for harsh conditions, such as low temperature (−50 °C). In this study, we utilized an organic base/urea catalytic system to efficiently achieve the controlled and selective ROP of EVP with trimethyl carbonate (TMC), under room temperature conditions, reaching an EVP conversion of 38% and producing the linear poly(TMC-co-EVP) copolymer. The detailed kinetic analysis and structural characterization revealed that the copolymerization proceeded via a transesterification mechanism. Thus, the synthesis of the poly(TMC-co-EVP) copolymer was also achieved directly from the PTMC homopolymer with EVP. Remarkably, this strategy was successfully extended to commercial polylactide (PLLA), leading to the convenient synthesis of the functionalized poly(LLA-co-EVP) copolyester with enhanced properties. These findings offer a promising strategy to efficiently utilize EVP under mild conditions and to design advanced CO₂-based materials.