Synthesis and properties of poly(ethylene-co-diethylene glycol 2,5-furandicarboxylate) copolymers

Poly(ethylene 2,5-furandicarboxylate) (PEF) is a biobased polyester with high gas barrier properties, tensile modulus, and strength. In PEF chain, in addition to ethylene furandicarboxylate repeat unit, there is also a small amount of diethylene glycol furandicarboxylate (DF) unit which is formed by etherification side reactions. However, the effect of DF unit in a wide composition range on polymer properties is still unclear. In this study, random poly(ethylene-co-diethylene glycol 2,5-furandicarboxylate) (PEDF) copolymers were synthesized via melt copolycondensation of 2,5-furandicarboxylic acid, ethylene glycol and diethylene glycol. The copolymers were characterized and evaluated by intrinsic viscosity, 1 H NMR, thermal transition, thermogravimetric analysis, tensile, impact, and O 2 penetration tests. The copolymers are amorphous in the full composition range. The presence of less than 58 mol% DF unit in PEDFs neither improves the tensile ductility nor deteriorates the oxygen barrier performance, but reduces the glass transition temperature clearly. In comparison with poly(ethylene terephthalate), the PEDF copolymers containing <58 mol% DF unit have higher tensile modulus, strength, and O 2 barrier properties.