Synthesis of Poly(butylene adipate terephthalate)-<i>co</i>-poly(glycolic acid) with Enhanced Degradability in Water

Abstract

As one of the most promising biodegradable polymers, poly(butylene adipate-co-terephthalate) (PBAT) has attracted immense attention in packaging and mulching film applications. However, their slow degradation performance in aqueous environments remains a great challenge. In this work, we focused on tailoring the chain structure of PBAT by introducing poly(glycolic acid) (PGA) into the copolyester backbone. The PBAT-co-PGA copolyesters with molar percentages of butylene terephthalate of 36.2–50.3 mol % and GA of 8.0–20.2 mol % and number-average sequence lengths of poly(butylene terephthalate) of 1.55–1.97 and PGA of 1.06–1.11 were synthesized using a melt copolycondensation. The number-average sequence length of the PBAT-co-PGAs can be tailored while maintaining the same monomer composition. The PBAT-co-PGAs exhibit higher Young’s modulus (88 MPa) and tensile strength (35 MPa) owing to their better crystallization ability compared with PBAT at the same terephthalic acid fraction. The incorporation of more terephthalic acid and glycolic acid results in an increase of glass transition temperature and the formation of a more rigid chain structure, which is beneficial to improving the water vapor barrier properties of the copolyesters. Importantly, the PBAT-co-PGA copolyesters show enhanced degradation properties in water environments without sacrificing their aging resistance. The synthetic strategy proposed here endows the PBAT-co-PGA copolyesters with a broad chain structure tailoring window, which renders them to exhibit excellent mechanical properties, water barrier, aging resistance, and, most importantly, accelerated hydrolysis performances in aqueous environments.