Synthesis of High-Toughness\nPolyesters Using Xylose\nand Lactic Acid and Analysis of Their Biodegradability

The production of plastic materials consumes a large\namount of\npetroleum resources, leading to the depletion of these resources and\nenvironmental problems associated with plastic disposal. Recently,\nthe demand for sustainable bioplastics has increased, necessitating\nan appealing strategy for the development of bioplastics using sustainable\nraw materials, including inedible resources that degrade rapidly under\nmild conditions. In this study, poly(alkylene xylosediglyoxylates)-<i>co</i>-poly(lactic acid) (PAX-<i>co</i>-PLA) is synthesized\nfrom xylose and lactic acid, which can be conditioned from inedible\nresources through a two-step condensation process. The thermal stability\nand mechanical properties can be tuned by changing the compositions\nof the copolymers. Among the PAX-<i>co</i>-PLA, PEX-<i>co</i>-PLA exhibits a high <i>T</i><sub><i>g</i></sub> (glass transition temperature) of 106 °C and PHX-<i>co</i>-PLA exhibits an elongation at a break of 106 ± 4%.\nThe biodegradability is evaluated, focusing on neat PHX and PHX-<i>co</i>-PLA, which exhibit high toughness. Both exhibit significant\ndisintegration in the compost. Neat PHX and PHX-<i>co</i>-PLA exhibit biodegradability by BOD (biological oxygen demand) of\n14% and 13% in seawater, respectively. Furthermore, PHX-<i>co</i>-PLA exhibits a contact angle (76.2 ± 1.7°) comparable\nto that of PLA, retains its shape for 2 weeks in water at 20 °C,\nand shows improved water resistance compared to neat PHX. With its\nthermoformability, water resistance, and partial biodegradability,\nPAX-<i>co</i>-PLA is expected to have wide applications\nand address environmental issues, including the reduction in microplastic\npollution.