Enhanced seawater degradation through copolymerization with diglycolic acid: Synthesis, microstructure, degradation mechanism and modification for antibacterial packaging

Marine plastic pollution is a worldwide challenge making new progress in the field of degradable polymers necessary. However, it is difficult for commercial biodegradable polymers, such as polylactide (PLA), to realize rapid degradation in seawater by simply blending modification. Here, we prepared a novel series of poly (butylene diglycolate/terephthalate) (PBDT) copolymers by introducing diglycolic acid into PBT. The proposed polyesters can serve as an eco-friendly substitute for existing packaging materials. The mechanical property of PBDTs, with high tensile strength (>23.4 MPa) and elastic modulus (95-610 MPa), had advantages compared with commercial degradable polymers. The hydrophilicity is enhanced with ether bonds of butylene diglycolate (BD) segments. And the hydrolysis of copolymers was accelerated in seawater, showing 16% weight loss after 30 days. Moreover, PBDTs with BD segments >= 20% performed great degradability in Phosphate Buffered Saline and enzymatic solution. And their degradation mechanism was monitored through various tests such as H-1 NMR, SEM and GPC. With a small number of antibacterial agents, such as 8% mass fraction of chitosan nanoparticles (CHNPs) or 1.0% of Ag@AgCl, PBDT composites could obtain good antibacterial ability for Gram-negative Escherichia coli without sacrificing the thermal, mechanical properties of the parent PBDT50. This work provides insights and direction for the development of seawater degradable polymers and thereby is able to relieve additional marine pollution in the future.

Automated summary

Marine plastic pollution is a global challenge that requires new progress in the field of degradable polymers. This study prepared a series of polyesters that can serve as eco-friendly substitutes for existing packaging materials. These polyesters have superior mechanical and degradation properties compared to commercial biodegradable polymers. Additionally, they exhibit good antibacterial ability when combined with a small number of antibacterial agents.