2,5-Furandicarboxylic acid (2,5-FDCA) is an oxidized furan derivative, firstly obtained by Fittig and Heinzelmann in 1876¹. It was recognized more than 125 years later by the US Department of Energy as one of the most important renewable building blocks, being the most credible substitute for terephthalic acid in the production of polyesters and other polymers containing aromatic moieties².
The global market for 2,5-Furandicarboxylic Acid in 2023 has been around US$532.5 million, and is expected to grow to US$811.9 million by 2030. Such growth is mostly due to the severe restrictions against polymer use, as well as carbon emission and the occurring transition towards sustainable products. Europe leads the 2,5-FDCA market with more than 42%, although the Asian market is expected to grow faster in the coming years. Interestingly, pharmaceutical sector is predicted to grow at a CAGR of 9.3% from 2022 to 2030, although the main market segment is represented by food packaging³.
In this framework, the present contribution aims to highlight the huge versatility of 2,5 FDCA-based polymers that, through an ad hoc chemical design, revealed to be valid candidates for a wide range of applications, from food packaging to biomedicine. High demanding sectors such as sensors will be also considered. Last, enzymatic recycling as a sustainable end-of-life option will be presented. The smart properties of furan-based materials will be highlighted through an overview of the most important results obtained by the research team I coordinate over the last 10 years, thanks also to fruitful national and international collaborations

Two furan-based monomers were derived starting from 5-bromofurfural, a furfural derivative, and sodium sulfide. Subsequent reaction steps gave the sulfide and sulfone containing monomers as dimethyl esters. Polyesters were then derived from various alkyl diols e.g., ethylene glycol, 1,4-butanediol, and diethylene glycol, in melt polycondensation reactions catalyzed by a titanium catalyst. The polyesters were processed into films via melt-pressing for further characterization. The sulfide bridge appeared especially beneficial for realizing films with low oxygen gas permeability while the sulfone bridge gave somewhat increased permeability. The polyesters derived from the sulfone containing monomer gave much higher glass transition temperatures (ca. 40 degrees higher) than those from the corresponding sulfide monomer. Interestingly, 1,3-propanediol appeared to give polyesters with the highest tendency to crystallize with both the sulfide or sulfone monomer, with other diols giving polyesters with largely amorphous character.

Recyclability was studied with both the sulfide and sulfone monomers with 1,5-pentanediol or diethylene glycol as the diol components. Free-standing films of all four polyesters could be chemically recycled back into monomers in a facile manner using methanol in the presence of catalytic potassium carbonate. Notably, diethylene glycol endowed the polyesters with room-temperature recyclability in methanol, providing yields >89% of the original sulfide and sulfone monomers with excellent purity.

As the global energy transition shifts towards renewable sources like solar, wind, and geothermal power, it is crucial to consider not only the performance of materials but also the sustainability of their production and end-of-life management. Conventional materials, while efficient, often neglect the environmental impact of their manufacturing processes and recyclability. This work focuses on developing green polymer materials and processes for organic photovoltaics (OPV), with an emphasis on enhancing the sustainability of electro- and photoactive π-conjugated polymers.(i) By incorporating biobased synthons into polymer synthesis, this approach aims to improve both the efficiency and environmental footprint of OPVs, addressing challenges related to biodegradability and recycling. This study specifically explores the use of furan-based monomers and polymers in OPVs, synthesized through microwave-assisted methods and electro-polymerization. These innovative techniques offer faster, more energy-efficient routes compared to traditional methods. Furan-based materials, with their inherent electronic properties, have shown promise as hole transport layers in organic solar cells, potentially enhancing device performance while reducing reliance on fossil-derived chemicals. By advancing sustainable polymer synthesis for OPVs, this research not only contributes to more eco-friendly energy solutions but also aligns with broader goals of circular economy and material sustainability in the renewable energy sector.

Furandicarboxylic acid (FDCA) is one of the most promising bio-derived monomers for the development of innovative bioplastics. It can be obtained through fermentation and dehydration of biomass and is recognized as one of the strategic building blocks derived from renewable raw materials. Among the polymers that can be synthesized from FDCA, furan-based polyesters, or poly(alkylene furanoate)s (PAFs), are particularly significant. Produced via the polycondensation of FDCA with alkylene glycols, PAFs exhibit thermo-mechanical and gas barrier properties that are comparable to, or even better than, those of poly(alkylene terephthalate)s (PATs), making them suitable for packaging applications. This study highlights recent progress achieved by our research group in applying poly(alkylene furanoate)s (PAFs) to modern plastic technologies. Different types of PAFs, varying in alkyl chain length, have been synthesized and employed in creating films, fibers, and electrospun mats. The focus has been on multifunctional PAF-based films and fibers designed for the packaging and textile industries. To address the inherent limitations of polylactic acid (PLA) and modify its physical properties, PAFs were combined with PLA at various concentrations using both solution blending and melt compounding. The impact of PAF content on the morphological, thermo-mechanical, and functional properties of the blends was thoroughly examined. This research offered valuable insights into the creation of multifunctional, high-performance bioplastic blends derived from renewable resources, aiming to meet the demands of the packaging and textile sectors. By understanding the relationship between blend morphology and properties, efforts to replace conventional plastics with customized biopolymers have been advanced.

Over the last decade, the issue of plastic pollution has prompted a shift towards bioplastics and paper-based materials over fossil-derived plastics, highlighting cellulose as a promising alternative as it is the most abundant organic polymer in nature [1]. However, cellulose's susceptibility to moisture significantly limits its mechanical performance and so its widespread application. To increase paper's mechanical strength in humid environments, wet-strength agents are employed, traditionally synthetic polymers like polyaminoamide-epichlorohydrin (PAE) and melamine-formaldehyde (MF) resin, which pose health risks due to carcinogenic compounds and hinder recyclability of final products. Consequently, research is directed towards natural alternatives to enhance process circularity [2].
This study focuses on developing a novel wet-strength agent derived from eugenol through a facile, economical, one-pot polymerization. Eugenol, obtainable from cloves or synthesized from lignin derivatives, is widely employed in the cosmetic and pharmaceutical sectors [3].
This approach aims to overcome the performance limitations of existing biopolymer-based agents. The resulting polymer (PEU) when impregnated into cellulose, imparts significant hydrophobic properties, demonstrated by water-contact angles exceeding 100°, and substantially enhances mechanical strength, evidenced by enhancement in Young's Modulus and resilience, even in humid conditions. These enhancements are achieved with low concentrations of PEU, attributable to its effective coverage of cellulose fibers, mimicking lignin's protective function. This natural, eugenol-derived polymer offers a sustainable solution, mitigating the drawbacks of synthetic wet-strength agents and advancing the development of high-performance, recyclable paper products.

Gas barrier properties are essential for food packaging materials, ensuring the preservation of goods. Poly(butylene 2,5-furandicarboxylate) (PBF), a fully biobased polyester, shows excellent gas barrier performance, making it a sustainable alternative to petrochemical plastics for single-material flexible packaging. However, understanding how crystallinity and water exposure affect PBF’s barrier properties is key to evaluating its potential for real-world applications. In this study, PBF was synthesized, characterized, and its gas barrier properties were investigated in dry and 85% RH atmosphere. For comparison, poly(butylene isophthalate) (PBI), a petrochemical analog with a benzene ring instead of the furan ring, and random PBF-PBI copolymers were synthesized and analyzed under identical conditions.
Gas permeability measurements revealed that, unlike PBI, amorphous PBF maintains its barrier performance in moist environments, while PBI exhibited a tenfold increase in permeability. Additionally, amorphous PBF-rich copolymers showed permeability reductions of up to -95% when transitioning from dry to wet conditions. This behavior was investigated using water-bath DMA, showing that water interacted uniquely with PBF, altering its relaxation behavior, hence mediating its barrier performance, while PBI exhibited a pure plasticization effect.
The impact of crystallinity was also evaluated under both dry and moist conditions. Crystallinity caused a slight deterioration in barrier performance under dry conditions for both PBF and PBI, whereas it significantly increased the permeability of PBI under wet conditions.
These findings underscore how PBF’s furan structure governs its interactions with water, offering the potential for high-barrier performance even in moist conditions.