Evidence of a 2D-Ordered Structure in Biobased Poly(pentamethylene furanoate) Responsible for Its Outstanding Barrier and Mechanical Properties

Among the various factors that contribute to the transition from a linear to a circular economy, the identification of superpolymers with outstanding mechanical as well as barrier properties and zero environmental impact has become a mandatory issue. Such new supermaterials render recycling a concrete option for the efficient and ecofriendly management of plastic wastes. In this study, a 100% biobased polyester has been prepared by a one-pot and solvent-free synthesis, starting from 2,5-furandicarboxylic acid and 1,5-pentanediol. At first, a molecular and thermal characterization of the polymer has been conducted and then processed to prepare a compression molded film, despite its amorphous and rubbery nature at room temperature. The mechanical response was typical of elastomers, with a low elastic modulus and stress at break and high elongation at break. An instant shape recovery after breaking was observed, indicating the presence of net points. The barrier properties to O2 and CO2 were exceptional and similar to those of ethylene vinyl alcohol (EVOH) and of polymer liquid crystals. All of these unexpected and surprising properties were explained as being due to the presence of a 2D microstructure characterized by partially ordered furanic rings favored by intermolecular C-H···O bonds.