High-performance sustainable active packaging from poly(hexamethylene furanoate) and bark extracts

The development of sustainable high-performance polymeric formulations, possibly showing multifunctional characteristics, is of key importance to produce materials in line with the circular economy agenda. This work focuses on the preparation of fully biomass-derived blends from furan-based polyester and natural extracts to yield an innovative packaging system. Terpenoids and suberin monomers are isolated from largely available waste biomass, namely, birch bark, through simple and straightforward methodologies and mixed with poly(hexamethylene furanoate) (PHF). The physicomechanical properties of the blends evidence a modulation of the surface hydrophobicity together with a significant increase in flexibility and toughness owing to the dual function exerted by the extracts, which act both as plasticizing agents and cross-linking molecules due to the formation of weak interactions, such as hydrogen bonding, with the macromolecular chains of PHF. The evaluation of the functional properties highlights that the excellent gas barrier characteristics of PHF are not just preserved; rather, a substantial increase of the CO2/O2 permselectivity ratio is measured because of the presence of an increased concentration of disclinations that favor the diffusion of CO2. Lastly, the addition of natural extracts allows for the implementation of antioxidant and antibacterial features otherwise absent in the pristine polymer.