Copolyesters containing terephthalic and bio-based furanic units by melt-polycondensation

5,5'-Isopropylidene-bis (ethyl 2-furoate), a monomer prepared from bio-based ethyl 2-furoate, was reacted with dimethyl terephthalate and ethan-1,2-diol (ED) by melt polycondensation in order to obtain copolyesters containing both terephthalate and furoate units. The conventional two-step method involving (i) the formation of a hydroxyethyl-terminated oligomer by reaction of starting diester mixture with excess ED and (ii) a polycondensation step with elimination of ED was used to obtain high molar mass copolyesters. Copolymers of various compositions were synthesized and characterized by H-1 NMR, DSC, and TGA. For all compositions, the degree of randomness, determined by H-1 NMR, was close to 1, reflecting a random distribution of terephthalic and furanic ester units in polymer chains. The resulting materials are amorphous polymers (T-g = 70-80 degrees C) with good thermal stability.