Furanic-Aromatic Copolyesters by Interchange Reactions between Poly(ethylene terephthalate) and Poly[ethylene 5,5′-isopropylidene-bis(2-furoate)]

Aromatic copolyesters containing bio‐based furanic units in the main chain were obtained by ester‐interchange reaction between poly(ethylene terephthalate) (PET) and poly[ethylene 5,5′‐isopropylidene‐bis(2‐furoate)] (PEF) at high temperatures in the bulk. Various copolyesters were synthesized by using PET/PEF mass ratios ranging from 90:10 to 50:50 and were characterized by 1H NMR, MALDI‐TOF MS, DSC, and TGA. PET/PEF block copolymers were formed in the first stage of reaction and then slowly randomized. The degree of randomness, determined by 1H NMR, was close to 1 after 2 h reaction. The randomization rate depended on the nature and the concentration of the end‐groups of starting homopolyesters and was much faster when a low molar mass hydroxy‐terminated PET was reacted. Reaction scheme showing the insertion of furanic units in copolyester chains by ester interchange reaction.