New multi-block copolyester of 2,5-furandicarboxylic acid containing PEG-like sequences to form flexible and degradable films for sustainable packaging

The copolymer was obtained through chain extension of two hydroxyl-terminated prepolymers prepared by polycondensation: poly(hexamethylene furanoate) PHF–OH, and poly(triethylene furanoate) PTEF-OH. The chain extended homopolymer PHF-CE was also synthesized for sake of comparison. Molecular, structural and thermal analyses evidenced that copolymerization has an impact on solidstate properties. The presence of the two different polymer blocks allows the obtaining of a tenacious material with high melting temperature, characterized by lower elastic modulus and improved elongation at break. To evaluate the potentiality of this new material in the field of food packaging, gas permeability behaviour to oxygen, carbon dioxide and nitrogen at 23 °C was evaluated: the synthetic path adopted leads to a improvement of the outstanding gas barrier performance in the multiblock copolyester with respect to the homopolymer. Composting tests showed that the molecular architecture plays a key role in determining a faster degradation rate.