Design of pH-dependent ZnO-reinforced electrospun poly(ethylene furanoate)/poly(3-hydroxybutyrate) nanofibrous membranes for sustainable food packaging

Abstract

We report on the manufacturing of 100% biorenewable co-electrospun membranes from poly(ethylene furanoate) (PEF) and poly(3-hydroxybutyrate) (PHB), loaded with ZnO, for food packaging applications. Co-solutions of both polymers were electrospun into nonwoven mats, and the impact of ZnO incorporation on the physical, chemical, and barrier properties was evaluated. The PEF/PHB nonwoven mats, though immiscible, revealed no phase separation when in the form of fibers. Added ZnO stabilized the co-spun nanofibers by interacting with hydroxyl groups, forming stabilized interactions that led to the entrapment of Zn2+ within the mat, tunable with the films' pH. Inclusion of ZnO in PEF/PHB improved the mechanical strength of the nonwoven mats by ∼77% and 70% in Young modulus and tensile strength, respectively. Water vapor transmission through the nonwoven mats was reduced with ZnO after 24 h (0.3 g day–1 from 0.4 g day–1). Furthermore, the release of entrapped Zn2+ in the blend nonwoven mats was investigated via response surface methodology as a function of temperature, pH, and time. Our results reveal that PEF/PHB+ZnO nonwoven mats disentangle to release trapped Zn2+ at low pH and high temperature, whereas low temperature and basic conditions force compaction, decreasing Zn2+ release.

Keywords: Poly(ethylene furanoate), Poly(3-hydroxybutyrate, )Nanofiber composites, Zinc Oxide, Electrospinning, Release kinetics