Poly(butylene 2,4-furanoate), an Added Member to the Class of Smart Furan-Based Polyesters for Sustainable Packaging: Structural Isomerism as a Key to Tune the Final Properties

Abstract

High-molecular-weight poly(butylene 2,4-furanoate) (2,4-PBF), an isomer of well-known poly(butylene 2,5-furanoate) (2,5-PBF), was synthesized through an eco-friendly solvent-free polycondensation process and processed in the form of an amorphous film by compression molding. Molecular characterization was carried out by NMR spectroscopy and GPC analysis, confirming the chemical structure and high polymerization degree. Thermal analyses evidenced a reduction of both glass-to-rubber transition and melting temperatures, as well as a detriment of crystallization capability, for 2,4-PBF with respect to 2,5-PBF. Nevertheless, it was possible to induce crystal phase formation by annealing treatment. Wide-angle X-ray scattering revealed that the crystal lattices developed in the two isomers are distinct from each other. The different isomerism affects also the thermal stability, being 2,4-PBF more thermally inert than 2,5-PBF. Functional properties, such as wettability, mechanical response, and gas barrier capability, were tested on both amorphous and semicrystalline 2,4-PBF films and compared with those of 2,5-PBF. Reduced hydrophilicity was determined for 2,4-isomer, in line with its lower average dipole moment, suggesting better chemical resistance to hydrolysis. Stress–strain tests have evidenced the higher flexibility and toughness of 2,4-PBF with respect to those of 2,5-PBF and the possibility of improving its mechanical resistance by annealing. Finally, the different isomerism deeply affects the gas barrier performance, being the O 2 - and CO 2 -transmission rates of 2,4-PBF 50 and 110 times lower, respectively, than those of 2,5-PBF. The gas barrier properties turned out to be outstanding under a dry atmosphere as well as in humid conditions, suggesting the presence of interchain hydrogen bonds. The gas blocking capability decreases after annealing because of the presence of disclination associated with the formation of crystals.

Monomers and Macromolecular Materials from Renewable Resources: State of the Art and Perspectives

“…This is where poly(ethylene 2,5-furandicarboxylate) (PEF) stands, which is now in process of being scaled up to industrial levels as a (often better) replacement of PET. The synthesis of poly(butylene 2,4-furandicarboxylate) was also demonstrated, and the material exhibited excellent gas barrier properties, thermal stability, flexibility, and toughness [ 130 ]. With the aim of describing a fully renewable polymeric material, cyclic oligomers based on 2,5-furan dicarboxylic acid and isomannide, a sugar-based structure to be tackled in the next section, were considered a few years ago [ 131 ].…”

Renewable Furfural-Based Polyesters Bearing Sulfur-Bridged Difuran Moieties with High Oxygen Barrier Properties

“…13 This is because the heteroaromatic FDCA moiety has certain similarities to the aromatic backbone moiety of PET, terephthalic acid. 14 In addition to ethylene glycol, a wide range of flexible longer aliphatic glycols have been used to prepare various FDCA-based polyesters: poly(propylene furanoate) (PPF), 15 poly(butylene furanoate) (PBF), 16,17 poly(pentamethylene furanoate) (PPeF), 18 and other poly-(alkylene furanoate)s. 19,20 They are typically synthesized via a polycondensation reaction between FDCA and the diol. Furan-based polymers are interesting as they do not rely only on renewability but they instead also leverage superior performance comparable to commercial terephthalate analogues.…”

Bio-based and one-day compostable poly(diethylene 2,5-furanoate) for sustainable flexible food packaging: Effect of ether-oxygen atom insertion on the final properties

“…Even though the use of additives, physical and chemical blending and production of composites are very effective tools to properly tune the material performances (Terzopoulou et al, 2020;Cowie and Arrighi, 2007;Poulopoulou et al, 2020), the starting point is definitely represented by a proper chemical design. Minor modifications in the chemical structure of a polymer, such as the overall composition, the atomic arrangement in the backbone, the length of the subunits in the repeating unit, the presence of side-groups and isomerism can lead to significant variations in physical properties (Sousa et al, 2015;Papageorgiou et al, 2016;Thiyagarajan et al, 2014Thiyagarajan et al, , 2019Soccio et al, 2008a;Bianchi et al, 2021;Nolasco et al, 2020a). Macromolecular mobility and the developed microstructure are strongly connected to the chemical structure of the polymer, thus affecting features like mechanical response, thermal stability, hydrophilicity, gas barrier performance and compostability (Robertson, 2013).…”