Highly Tough, Barrier, and Biodegradable Copolyesters Synthesized from Furandicarboxylic Acid

Biobased polyesters based on 2,5-furandicarboxylic acid show great potential for replacing conventional plastics, but their practical applications are still limited by the inherent brittleness of the materials. A series of high molecular-weight poly(ethylene-diethylene glycol 2,5-furandicarboxylate) (PEDF) copolyesters were synthesized by introducing diethylene glycol, which contained a flexible oxygen ether bond. The thermal stability, mechanical properties, and optical transparency of the PEDF copolyesters improved significantly with the increasing diethylene glycol content. The elongation at break of PED₄₀F can reach 43% which is up to 10.7 folds compared with PEF and maintains a high tensile modulus of 2440 MPa and a tensile strength of 74 MPa, as well as a mass loss of 45.79% after 49 days under CALB enzymatic degradation conditions. In addition, PEDF copolyester has excellent gas barrier properties, with carbon dioxide and oxygen barrier improvement factors (BIFp) 13.0 and 7.3 times higher than those of PET.