Synthesis and characterization of α-1,3-glucan-graft-poly(L-lactide) copolymers exhibiting controllable seawater biodegradability and thermoplasticity
Zhengyu Su, Jin Ho Seok, Satoshi Kimura, Tadahisa Iwata
Abstract
ABSTRACT 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.