Synthesis and characterization of α-1,3-glucan-graft-poly(L-lactide) copolymers exhibiting controllable seawater biodegradability and thermoplasticity

• Thermoplastic α-1,3-glucan- graft -PLA copolymers were synthesized in ionic liquid with MS PLA values tunable from 2.2 to 22.4. • The graft copolymers exhibited single T g values decreasing from 94 °C to 46 °C and mechanical properties shifting from rigid to flexible with increasing MS PLA value. • All samples showed efficient biodegradability in seawater; the synthesized α-1,3-glucan- graft -PLA copolymers are fully bio-based and show a great potential for marine-disposable applications. α-1,3-Glucan- graft -poly( l -lactide) (PLA) copolymers were successfully synthesized in an ionic liquid at 80°C using 4-dimethylaminopyridine as an organic catalyst. The molar substitution degree of the PLA grafted side chains (MS PLA ) ranged from 2.2 to 22.4. The structures and thermal properties of the α-1,3-glucan- graft -PLA were characterized. Their glass transition temperatures ( T g ) progressively decreased from 94°C to 46°C as the MS PLA increased. Films of these copolymers were prepared, and the results of tensile experiments showed that higher MS PLA values resulted in a transition from rigid to flexible mechanical properties. Furthermore, biodegradability was evaluated using seawater biochemical oxygen demand tests, which confirmed that all samples degraded efficiently and the rate of degradation increased with decreases in the MS PLA . These results demonstrate that it is possible to adjust the thermoplasticity, mechanical properties, and biodegradability of α-1,3-glucan- graft -PLA copolymers by adjusting the MS PLA , which shows potential for sustainable bioplastic applications.