Enhanced degradation and gas barrier of PBAT through composition design of aliphatic units

Aliphatic–aromatic copolyesters are indispensable in degradable plastics, but their properties are limited by low strength and modulus, and slow degradation rates in natural environment. Herein, we report a novel molecular design method to prepare poly(butylene adipate–co–diglycolate–co–terephthalate)(PBADT) copolyesters. In detail, the aromatic unit is fixed at 50% molar content of butylene terephthalate (BT) units, while the aliphatic units are consisted of butylene adipate (BA) and butylene diglycolate (BD) units. The PBADT copolyesters have melting temperatures higher than 130 °C and manifest rapid crystallization, high elastic modulus (>129 MPa) and satisfied ductile tensile behavior (>770%). Their gas barrier performance and hydrophilicity all increase with increasing BD units. Compared with PBAT, faster hydrolysis and seawater degradation are observed, which is explained by the more hydrophilic structure of diglycolate. This work provides insights and direction for the development of high-performance yet environmentally degradable alternatives to conventional biodegradable aliphatic–aromatic polyesters.