Potentially Biodegradable “Short-Long” Type Diol-Diacid Polyesters with Superior Crystallizability, Tensile Modulus, and Water Vapor Barrier

Long-chain aliphatic polyesters are potential biodegradable polymers having PE-like structure and properties. To develop biodegradable long-chain polyesters for practical applications, a series of “short-long” type long-chain polyesters, PEsxy (x = 2–4, 6, y = 10–16), are designed and synthesized from C_2–4,6 short-chain α,ω-diols and C_10–16 long-chain α,ω-diacids via melt polycondensation. They showed intrinsic viscosity as high as 0.93–1.64 dL/g and PE-like crystal structure, rapid crystallization, and ductile tensile behavior. Their crystallization and melting temperature showed an increasing trend with diacid chain length and a clear odd–even effect. The highest melting temperature reached 94 °C, and the highest tensile strength reached 53 MPa. Chain length-dependent biodegradability in soil and hydrolytic degradation under neutral conditions at 30–60 °C was also observed. In comparison with the widely used biodegradable poly­(butylene adipate-co-terephthalatae) (PBAT) copolyester, these polyesters show comparable tensile strength, ductility, and oxygen barrier performance, but obviously superior and desirable crystallizability, tensile modulus, and water vapor barrier performance.