Development of completely furfural-based renewable polyesters with controllable properties

Abstract

Two series of completely furfural-based poly(butylene succinate) (PBS) and poly(butylene 2,5-furandicarboxylate) (PBF) ternary-copolyesters were obtained by melt polycondensation of succinic anhydride (SA) or 2,5-furandicarboxylic acid (FDCA) with 1,4-butanediol (1,4-BDO) and tricyclic diacid (TCDA), leading to a total carbon utilization of furfural. Notably, a practical furfural-to-FDCA conversion process was demonstrated via K₂CO₃ promoted C–H carboxylation of furoate in molten sodium formate. The novel copolyesters displayed controllable thermal, mechanical and gas barrier properties over a wide range, in addition to crystallization behavior, by varying polymer composition using different feeds of the linear SA, planar FDCA and stereoscopic TCDA building blocks. In addition, a series of novel quadri-copolyesters (PBTC_x(S_nF_m)_y) with comparable properties to petrochemical-based plastics were synthesized from SA, FDCA, TCDA and 1,4-BDO. In particular, PBTC₁₅(S₁₀F₉₀)₈₅ exhibited satisfactory T_g (36.7 °C) and tensile strength (46.9 MPa) comparable to those of poly(butylene terephthalate) (PBT), in addition to superior ductility (ε_b = 830%) and CO₂ barrier properties (0.029 barrer) when compared with poly(ethylene terephthalate) (PET). A strategy to convert furfural biomass into polymerizable monomers provides a feasible route in commercializing furfural and accessing a variety of novel renewable polyesters that are promising alternatives to existing commercial petrochemical-based polyesters.