LAUSR

Poly(ethylene 2,5‐furandicarboxylate) (PEF) and poly(butylene 2,5‐furandicarboxylate) (PBF) are regarded as two of the most promising materials derived from furandicarboxylic acid. The modification of these two polyesters has become one of the hot research topics. It was reported that their mechanical properties had significant shortcomings, particularly for low molecular weight PBF, whose brittleness limited its use. In this work, a novel monomer, itaconic acid, was introduced to modify PBF, and a new furan‐based polyester‐poly(1,4‐butylene furanoate‐co‐itaconate) (PBFIs) was synthesized. For the first time, itaconic acid up to 47% was incorporated to synthesize the polyester materials. The structural and thermomechanical properties of these polyesters were investigated using Gel Permeation Chromatography (GPC), Proton Nuclear Magnetic Resonance (1H NMR), Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), X‐ray Diffraction (XRD), and tensile testing. Compared to PBF, the PBFIs exhibited reduced crystallization ability attributed to the formation of crosslinked networks; notably, their glass transition temperature decreased significantly to as low as 7°C, while thermal stability improved. Tensile tests further demonstrated that their elongation at break increased dramatically by up to 675%. In summary, the results suggest that PBFIs possess significant potential in the realm of thermoset elastomers, thereby expanding the application scope of furan‐based polyesters.