Biodegradable aliphatic poly(carbonate-co-ester)s containing biobased unsaturated double bonds: synthesis and structure-property relationships

A series of aliphatic poly(carbonate-co-ester)s (PBCFs) were successfully synthesized via melt polycondensation of 1,4-butanediol (BD) and dimethyl carbonate (DMC) in the presence of biobased fumaric acid (FA). The prepared unsaturated copolymers had weight-average molecular weights (Mw) in the 4.98 × 104 to 8.82 × 104 g·mol−1 range and from 1.56 to 1.83 polydispersities. They all had random microstructures. The physical properties of the novel poly(carbonate-co-ester)s, such as melting temperature (Tm) and melting enthalpy (∆Hm), varied widely depending on their composition. The stiff fumaric acid units in the poly(butylene carbonate) (PBC) chain caused an increase in the glass transition temperature (Tg) and thermal stability. Furthermore, PBCF10 to PBCF20 (with fumaric acid unit content of <19%) contained PBC crystals, while the lattice structure of PBCF40 to PBCF80 (with fumaric acid unit content greater than 37%) was similar to that of the poly(butylene fumarate) (PBF) type. The mechanical properties and biodegradability of the copolymers were also studied.