A renewable tricyclic building block towards synthesis of biobased polyesters with high-performance and hydrolyzability

The development of biobased polyesters which concurrently achieve high‐performance and hydrolyzability, is a significant challenge. Here N,N′-trans-1,4-cyclohexane-bis(pyrrolidone-4-methyl carboxylate) (CBPC), a tricyclic diester, was prepared by Michael addition-cyclization from renewable feedstocks. Single-crystal X-ray revealed an unfolded skeleton of CBPC, in which two pyrrolidones symmetrically disposed in non-planar space around the cyclohexane. CBPC exhibited a high reactivity to be polymerized with various diols to generate biobased polyesters with high number-average molecular weight over 40 kDa. The tricyclic structure imparts the high glass transition temperature (Tg) (over 100°C), tough mechanical properties (tensile strength up to 56.8 MPa) as well as noticeable hydrolytic degradation to the resulting polyesters, which exhibit great potential to compete with commercial polyesters of polyethylene terephthalate (PET), polylactic acid (PLA) and polybutylene terephthalate (PBT). The hydrolytic pathway and reactivity site of the polyesters were further elucidated by the theoretical calculation. Note that PBT, PET and PLA are extremely reluctant to hydrolyzation, a higher sensitivity to hydrolysis is desired for high-performance polyester to reduce environmental impact. Overall, this work addresses some critical requirements for high-property polyesters which concurrently achieve high Tg values, tough mechanical properties, wide process windows, and hydrolysis quality.