Superior sequence-controlled poly(L-lactide)-based bioplastic with tunable seawater biodegradation
Manjie He, Yu‐I Hsu, Hiroshi Uyama
Abstract
Developing superior-performance marine-biodegradable plastics remains a critical challenge in mitigating marine plastic pollution. Commercially available biodegradable polymers, such as poly(L-lactide) (PLA), undergo slow degradation in complex marine environments. This study introduces an innovative bioplastic design that employs a facile ring-opening and coupling reaction to incorporate hydrophilic polyethylene glycol (PEG) into PLA, yielding PEG-PLA copolymers with either sequence-controlled alternating or random structures. These materials exhibit exceptional toughness in both wet and dry states, with an elongation at break of 1446.8% in the wet state. Specifically, PEG4kPLA2k copolymer biodegraded rapidly in proteinase K enzymatic solutions and had a significant weight loss of 71.5% after 28 d in seawater. The degradation primarily affects the PLA segments within the PEG-PLA copolymer, as evidenced by structural changes confirmed through comprehensive characterization techniques. The seawater biodegradability, in line with the Organization for Economic Cooperation and Development 306 Marine biodegradation test guideline, reached 72.63%, verified by quantitative biochemical oxygen demand analysis, demonstrating rapid chain scission in marine environments. The capacity of PEG-PLA bioplastic to withstand DI water and rapidly biodegrade in seawater makes it a promising candidate for preventing marine plastic pollution. Emerging high-performance marine-biodegradable plastics are widely considered the ideal strategy to address marine plastic pollution. However, the complex and harsh conditions of the marine environment severely inhibit the biodegradability of plastics. To accelerate polymer degradation in the ocean, bioplastics have been designed by structurally incorporating hydrophilic PEG units into bio-based PLA, yielding PEG-PLA copolymers with either sequence-controlled alternating or random structures. These copolymers exhibit tunable and superior mechanical properties, and undergo rapid yet tunable biodegradation in seawater within 28 days, offering a potential solution for tackling marine plastic pollution.