Multifunctional films based on tannic acid-coated cellulose nanocrystals and zinc-coating reinforced sodium carboxymethyl cellulose/polyvinyl alcohol for food active packaging.

Multifunctional packaging materials made from biomass resources are key to achieving packaging storage and environmental friendliness. The aim of this study is to prepare high-performance cellulose-based packaging films to improve the high-value utilization of cellulose resources. In this paper, the blended films of sodium carboxymethyl cellulose (CMC) and poly(vinyl alcohol) (PVA) were used as the substrate and doped with tannic acid (TA)-coated cellulose nanocrystals (CNC@TA). Then, zinc ions (Zn) were decorated on the film surface by adsorption self-assembly. The modified films (Z-CPC@T films) were prepared with excellent mechanical properties (tensile strength and elongation at break of 73.85 MPa and 19.68 %, respectively). Meanwhile, the presence of CNC@TA provided the films with UV and oxidation resistance. In addition, the zinc coating formed on the film surface conferred water resistance, hydrophobicity, and structural stability (water contact angle up to 97.09°). The modified films also showed excellent antimicrobial and water-vapor barrier properties. The modified films preserved cherries for at least 16 days with a quality retention of 87.20 %. In addition, cytotoxicity tests confirmed the non-toxic properties of the modified films. Overall, this strategic fusion of internal and external dual crosslinking expanded the application potential of active packaging materials.