Hydrogen Bonding Regulated 2,5-Furandicarboxylic Acid Diester Plasticizers: From Design of Side-Chain to Evaluation of Plasticizing Properties

2,5-Furandicarboxylic acid (FDCA), a key biobased monomer for polyesters and polyamides, must be highly purified, and this costly purification hampers its commercialization. To circumvent this limitation, five diester plasticizers containing alkyl, ether, or ester substituents were synthesized from crude FDCA to modulate hydrogen-bonding interactions in PVC blends. Diesters with unbranched chains and more hydrogen-bonding interactions, bis(2-butoxyethyl) furan-2,5-dicarboxylate (FDCA-EG) and bis(2-butoxy-2-oxoethyl) furan-2,5-dicarboxylate (FDCA-GA), exhibited superior plasticization efficiency relative to the commercial plasticizer DEHP, as evidenced by increased elongation at break and reduced glass-transition temperature ( T g ). FTIR characterization revealed a negative, quantitative correlation between T g and total hydrogen-bond strength, whereas mechanical properties were insensitive to this parameter. Furthermore, the FDCA-based plasticizers displayed markedly lower migration in hexane than in DEHP.