Polyvinyl Alcohol/Polyethyleneimine-Modified MXene Nanocomposite Coatings for Food Packaging: Enhanced Mechanical, Barrier, and Antimicrobial Properties

Polyvinyl alcohol (PVA) is a synthetic and biodegradable polymer with high oxygen barrier property. However, its practical application as coatings in food packaging is limited by insufficient mechanical strength, poor water resistance, weak UV shielding performance, and a lack of active antimicrobial functionality. In this study, polyethyleneimine (PEI) modification not only improved the dispersion of Ti 3 C 2 T x MXene but also endowed the PVA film with enhanced mechanical properties, superior water resistance, barrier performance, antimicrobial, and UV-shielding capabilities. The results showed that compared with neat PVA film, the nanocomposite with 4 wt% PMXene (PEI modified MXene) exhibited a tensile strength increase from 27.8 MPa to 38.4 MPa, representing a 38% improvement. The water vapor transmission rate decreased from 35.5 g/m 2 ·24 h to 29.0 g/m 2 ·24 h, and the oxygen transmission rate dropped from 1.5 cm 3 /m 2 24 h to 0.7 cm 3 /m 2 ·24 h. The PVA nanocomposite coating with 6 wt% PMXene blocked 97% of UV light and exhibited antibacterial efficacy exceeding 99% against Staphylococcus aureus and Escherichia coli . A fruit preservation test further confirmed that the composite coating can effectively prolong the storage life of cherry tomatoes. Therefore, these PVA nanocomposites demonstrate potential use in packaging applications in the food industry and pharmaceutical storage fields.