Modification of Biodegradable Poly(butylene carbonate) with Succinic Acid: High Thermal and Barrier Properties

Poly(butylene carbonate) (PBC), which originates from carbon dioxide (CO2), is a very important member of the family of biodegradable polymers. In order to enhance the melting point (Tm), thermal stability, and barrier properties of PBC, a series of poly(butylene carbonate-co-butylene succinate) (PBCS) random copolyesters with weight-average molecular weights ranging from 79600 to 139800 g/mol were synthesized via melt polycondensation from dimethyl carbonate, succinic acid, and 1,4-butanediol. In detail, the chemical structures and properties were evaluated. The results indicate that the incorporation of butylene succinate (BS) units into the molecular chain of PBC can significantly regulate the thermal transition properties, crystal behavior, and thermal stability. Tm of PBC increases from 60.4 to 104.2 °C for PBCS88, and Td,5% rises from 288 to 324 °C. Despite being influenced by crystallinity, mechanical properties do not linearly increase with the rising content of BS units; they remain satisfactory. The maximum barrier properties of PBCSs for CO2 and O2 are respectively 6.3 and 5.5 times greater than those of poly(butylene adipate-co-terephthalate) (PBAT). Impressively, the water vapor barrier is as high as 40.8 times. In addition, PBCSs demonstrate degradation capability in a phosphate-buffered solution, an enzyme environment, and a composting environment, particularly achieving complete degradation within 4–8 days in enzyme environments. This work provides a new strategy to improve the overall properties of PBC, resulting in PBCSs, a renewable and ecofriendly polymer material. By adjustment of the BS unit content, diverse properties can be achieved to meet the demands of application in the packaging, film, and medical fields.