Synthesis, crystallization behavior and mechanical property of biodegradable Poly(butylene succinate-co-2-methyl succinate) copolyesters

In this research, a series of biodegradable poly(butylene succinate-co-2-methyl succinate) (PBSMS) random copolyesters with butylene 2-methyl succinate (BMS) unit content from about 10 to 90 mol% were successfully synthesized. Both the homopolymers poly(butylene succinate) (PBS), poly(butylene 2-methyl succinate) (PBMS), and PBSMS copolyesters showed relatively high intrinsic viscosity values of over 0.8 dL/g. The basic thermal parameters, crystallization behavior, crystal structure, spherulitic morphology and growth rate, and mechanical properties of PBSMS copolyesters were extensively studied and compared with those of PBS. The incorporation of methyl group not only effectively increased the toughness of PBSMS copolyesters but also significantly restrained the crystallizability of these copolyesters, showing that PBSMS copolyesters with the BMS unit content higher than 50 mol% were amorphous. Among these copolyesters, PBSMS30 (BMS unit content = 30 mol%) exhibited the most outstanding mechanical properties, with a Young's modulus of 188.0 +/- 19.1 MPa, a tensile strength of 19.1 +/- 1.8 MPa, and an elongation at break of 714.5 +/- 23.2 %. By randomly introducing methyl as a side group into the PBS main chain, the mechanical properties of PBSMS copolyesters have been significantly improved. From the perspective of structure and properties, this study should be interesting and crucial for the development and research of biodegradable polymers.