A tough and water-resistant cellulose-based barrier film and its multiple synergistic mechanisms for fruit preservation.

Cellulose-based packaging films represent a significant direction in sustainable materials science. However, their application is often hindered by the challenge of low water vapor barrier properties under high humidity conditions. In this work, carboxymethyl cellulose (CMC)/Mica@TiO2 (titanium dioxide) composite films with high water vapor barrier and water resistance were prepared via the green process, including acid-assisted gelation, cyclic freeze-thaw, and directional deposition. Flake Mica@TiO2 extends the water vapor transport path and improves the stability of the water vapor barrier. Furthermore, the Passive Radiative Cooling (PRC) effect of TiO2 contributes to the composite film's high reflectance (93.81 %) and emittance (96.57 %) of sunlight, which reduces the film's temperature by over 12.1 °C and effectively hinders the diffusion and transport of water vapor. The water vapor permeability coefficient (WVP) of the composite film is as low as 28.62 × 10-12·g·m/m2·Pa·s (37 °C, 65 % Relative Humidity (RH)). In addition, the composite film exhibits high wet tensile strength (28.9 MPa), excellent UV shielding rate (93.12 %), and antibacterial performance (98.5 % inhibition against Escherichia coli (E. coli)). This multifunctional V-CMC/Mica@TiO2 composite film provides an innovative, environmentally friendly, and highly efficient solution for food preservation and is expected to promote the sustainable development of the food packaging industry.