Biodegradable poly(lactic acid) and polycaprolactone alternating multiblock copolymers with controllable mechanical properties

As the environmental pollution problems caused by plastic waste and the dependence on petroleum resources become more serious, the need for biodegradable plastics and bioplastics is increasing. Recently, poly(lactic acid) (PLA), one of the leading biodegradable plastics, has been widely used as a biomass plastic to replace petroleum-based materials. However, PLA is brittle and does not decompose easily in real environments, limiting its use. In this study, PLA was copolymerized with polycaprolactone (PCL) to obtain triblock copolymers PLA-PCL-PLA, and then chain-extended by hexamethylene diisocyanate to obtain PLA-PCL alternating multiblock copolymers based on PLA. By varying the chain lengths of PLA in the alternating multiblock copolymers, the mechanical properties could be easily controlled, and the toughness was significantly improved compared to PLA-PCL random co-polymers. Evaluation of biodegradability in compost showed improved CO2 production and biodegradation rate in the initial stage of the test, suggesting high biodegradability. The change in molecular weight of the copolymer films in seawater did not prove marine biodegradability, but it was assumed that the copolymer's regularly arranged structure and low Tg contributed to its low molecular weight, one of the key factors in PLA biodegradation.

Automated summary

As the environmental pollution caused by plastic waste and dependence on petroleum resources become more serious, the demand for biodegradable plastics and bioplastics is increasing. This study successfully improved the toughness and biodegradability of poly(lactic acid) (PLA) through copolymerization.