Poly(ether-ester)s synthesized from furandicarboxylic acid and ethylene glycol using an acidic binary catalyst

Poly(ethylene 2,5-furandicarboxylate) (PEF) is an important biobased polyester with better thermal, mechanical, and gas barrier properties than poly(ethylene terephthalate). In PEF synthesis, diethylene glycol furandicarboxylate (DF) is inevitably formed via etherification side reaction. Taking advantage of the side reaction, poly(ethylene-co-diethylene furandicarboxylate) (PEDF) poly(ether-ester)s were synthesized only from 2,5-furandicarboxylic acid (FDCA) and ethylene glycol (EG), using a cheap binary propanedisulfonic acid/dibutyltin oxide (PSA/DBTO) catalyst. The polymers were characterized by 1 H NMR, intrinsic viscosity, solubility, differential scanning calorimetry, thermogravimetric analysis, tensile, and gas barrier test. Due to strong acidity of PSA, not only major DF but also minor oligoethylene glycol furandicarboxylate ether-containing units were formed. Their total content can be adjusted up to 78 mol% by simply increasing the dosage of PSA from 0 to 0.4 wt%. The effect of ether-containing units on the solubility, thermal transition, mechanical, and oxygen barrier properties of the poly(ether-ester)s were examined and compared with the poly(ether-ester)s synthesized via copolycondensation.