A green and sustainable −COOH & −OH condensation solution polymerization method for FDCA-based polyesters.

Abstract

A green and sustainable −COOH & −OH condensation solution polymerization method was hereby reported for FDCA-based polyesters to avoid discoloration and toxic solvents. First, taking poly(ethylene 2,5-furandicarboxylate) (PEF) as the representative of FDCA-based polyester, enabling good white appearance PEF with M _n=6.51×10³ g mol⁻¹ from FDCA and ethylene glycol in green solvent γ-valerolactone (GVL), catalyzed by 4-dimethylaminopyridine (DMAP) and N-(3-dimethylaminopropyl)-N’-ethylcarbodiimide hydrochloride (EDC). Additionally, the molecular weight of PEF was rapidly improved (M _n >2.5×10⁴ g mol⁻¹) via remelting polycondensation within minutes, with the dispersity still kept relatively low dispersity (Đ<1.40). Importantly, the −COOH & −OH condensation solution polymerization method was successfully applied for the synthesis of various FDCA-based polyesters, including diols with varying carbon chain lengths (3 to 11 carbons) and cycloalkyl diols, especially the applicability of this method to diols containing C=C double bonds, which was found to exhibit low heat resistance. Lastly, assisting with ¹³C labeled 1,4-succinic acid and in-situ ¹³C-NMR, an in-depth study of the possible catalytic mechanism was proposed, by which, EDC activated FDCA, and then DMAP catalyzed it with diol to yield macromolecular chain of polyester. Overall, the results provided a green and sustainable strategy for the synthesis of FDCA-based polyesters.