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 ( M w ) in the 4.98 × 10 4 to 8.82 × 10 4  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 ( T m ) and melting enthalpy ( ∆H m ), 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 ( T g ) 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.