Synergistic Modification of PBT with Diglycolic Acid and Succinic Acid: Fast Crystallization and High Strength-Toughness Copolyesters for Environmentally Degradable Packaging

• Published in: ACS sustainable chemistry & engineering Vol. 11; no. 38; pp. 14068 - 14080
• Main Authors: Hu, Han, Lin, Chen, Luan, Qingyang, Jiang, Xiaoyu, Zhang, Xiaoqin, Wang, Qianfeng, Dong, Yunxiao, Wei, Jing, Wang, Jinggang, Zhu, Jin
• Format: Journal Article
• Language: English
• Published: American Chemical Society 25.09.2023
• Subjects: Fast crystallization; Oxygen heteroatom; Aliphatic-aromatic copolyesters; Green packaging; Environmental degradation
• ISSN: 2168-0485; 2168-0485
• DOI: 10.1021/acssuschemeng.3c03394

Biodegradable polymers tend to undergo relatively slow degradation under natural conditions, facing challenges in ecofriendly applications. The copolymerization modification of the amorphous region of aliphatic–aromatic copolyesters has become an effective method to juggle outstanding comprehensive performance and adjustable degradation. Herein, a series of poly­(butylene succinate diglycolate terephthalate) (PBSDT) copolyesters were successfully prepared, realizing synergistic modification of the amorphous phase with diglycolic acid and succinic acid. In detail, PBS40D10T to PBS10D40T were designed to explore the differences in molecular characteristics and properties. We find that the similarity of these two segments reflected in segmental rigidity and domain size, also displaying comparable melting temperature and mechanical properties. The PBSDT copolyesters exhibited higher melting temperature (>141 °C), elastic modulus (>120 MPa), and tensile strength (>25 MPa) than commercial PBAT. Their gas barrier performance achieved 20 times better than PBAT and 4 times better than PLA, also being superior to that of PBAT/PLA blends. The differences of two comonomers were mainly attributed to the oxygen heteroatom of diglycolic acid, reflected in the hydrophilicity and stronger intermolecular interactions, which significantly influenced their crystal growth rate and environmental degradation. Especially, the isothermal crystallization rate (minimum t 1/2 < 15s) was the fastest among reported aliphatic–aromatic copolyesters. In addition, the degradation behavior clarified that the preferentially depolymerized diglycolate can be a decisive factor in controlling the degradation rate. Remarkably, synergistic modification by diglycolic acid and succinic acid endowed the access to enhanced hydrolytic degradability in a natural environment, without sacrificing the thermal, mechanical, and gas barrier properties. This work provides a new direction for the high strength-toughness green packagings and alternatives to PBAT with tunable degradation.