Biobased Random Copolymers From Furandicarboxylic Acid Isomers: Proof of Concept for an Integrated Biorefinery Approach Toward Outstanding Sustainable Food Packaging

This work explored the industrial potential of an alternative green synthetic route to obtain 2,5-furandicarboxylic acid (2,5-FDCA) via a Henkel-type disproportionation reaction developed by Thiyagarajan et al., meant to produce furan, and up to 30% of 2,4-furandicarboxylic acid (2,4-FDCA), a structural isomer of 2,5-FDCA. Linear glycols were combined with FDCA isomers from the Henkel-type reaction to synthesize three fully biobased random copolymers: 2,5-2,4-PTF, 2,5-2,4-PBF, 2,5-2,4-PHF. These copolymers were compression molded and subjected to NMR, viscometry, WAXS, DSC, and TGA analyses. Evidence suggested the formation of a partially ordered phase in 2,5-2,4-PHF. Mechanical and gas barrier properties of the synthesized copolymers were remarkably superior to the ones of both the reference homopolymers, with increased toughness, elongation at break and resistance to humidity. Interestingly, humidity improved the gas barrier performance of 2,5-2,4-PBF, making it impermeable to CO2. These findings highlighted the potential of these furan-based copolyesters for the production of mono-material, potentially recyclable, and sustainable food packaging. These achievements represented promising proof of concept for an integrated biorefinery and polymerization process, designed to: 1) Completely avoid the use of solvents; 2) Start from second-generation biomass; 3) Have high carbon efficiency and few purification steps.