Fully Biobased Copolyesters with High Gas Barrier and Enhanced Mechanical Properties Derived from 2,5-Thiophenedicarboxylic Acid and Long-Chain Dicarboxylic Acid

This work provides an in-depth molecular structure design strategy for developing high-barrier polymer packaging films. A series of high-performance PPDThF copolyesters were prepared by utilizing the unique crystallization ability of poly(propylene 2,5-thiophenedicarboxylate) (PPThF), as well as a long-chain dicarboxylic acid, namely dodecanedioic acid (DA). The incorporation of a polyethylene-like polyester structure from DA into the main chain of polymers has been found to be random copolymerization, leading to limited crystallizable sequence lengths. The effects of the long-chain dicarboxylic acids on the thermal transition, aggregation structure, gas barrier properties, and optical properties of the copolyester PPDThF copolyesters were investigated. The results demonstrate that PPDThF-10 combines the benefits of conventional thermoplastics, like high strength (>30 MPa) and high modulus (>0.6 GPa), with the mechanical and physical characteristics of chemically cross-linked rubber, including high extensibility (ε = 730%) and toughness (134 MJ/m–3). The results obtained so far demonstrate that thiophene-based copolyesters can be used in food packaging applications.