Enhanced Marine Biodegradability of Poly(Lactic Acid)-Based Polyurethanes via Alkylene Diglycolate Incorporation

Poly(L-lactic acid) (PLLA) is a widely used biodegradable polymer with potential environmental applications. However, its biodegradability under marine conditions is limited, especially for high molecular weight variants. This study aims to develop PLLA-based materials with enhanced biodegradability in seawater by incorporating alkylene diglycolate structures into the polymer backbone. Novel PLLA-based polyurethanes (PLLAUs) were synthesized via ring-opening polymerization of L-lactide using alkylene diglycolates as initiators, followed by chain extension with hexamethylene diisocyanate. The biodegradability of the PLLAUs in seawater was evaluated using biochemical oxygen demand (BOD) measurements. The incorporation of alkylene diglycolate structures facilitated degradation by accelerating the slow extracellular hydrolysis stage, which is responsible for the poor biodegradability of high molecular weight PLLA. The results indicated that PLLAUs containing alkylene diglycolate segments exhibited greater biodegradability than conventional PLLA of similar molecular weight in seawater. The PLLAUs also exhibited greater tensile strength and elongation at break compared to conventional PLLA.