Furan-based poly(esteramide)s by bulk copolycondensation

Polyesteramides based on diethyl 5,5′-(propane-2,2-diyl)-bis(furan-2-carboxylate), a biobased diester, are synthesized by high temperature bulk polycondensation with mixtures of hexane-1,6-diamine and ethane-1,2-diol. The ester/amide ratio in final copolymers is governed by the initial diester/diamine ratio, any diol excess being eliminated during the synthesis via a series of interchange reactions. The copolyesteramides are thermally stable, amorphous compounds. Their structural characterization shows the existence of minor side reactions: diol etherification, and two reactions, specific to furan-2-carboxylate structure, the formation of nonreactive 2-furyl end groups and chain branching resulting from amidine formation by amide–amine condensation.