Facile Preparation of Chitosan/Carnauba Wax Emulsion‐Based Coatings for Hydrophobic and Oleophobic Cellulose‐Based Food Packaging

Studies have shown that fluoridated reagents for oil and water resistance are harmful to the human bodies and the environment. Consequently, the developments of nontoxic, environmentally friendly, fluorine‐free and degradable materials have received increasing attentions. Here, we introduce a novel method for fabricating a hydrophobic and oleophobic paper‐based packaging material through the application of chitosan/carnauba wax emulsions. These emulsions were prepared via high‐shear homogenization, blending melted carnauba wax with chitosan in acetic acid aqueous solutions. The stable chitosan/carnauba wax emulsion with particle size of 430 nm was prepared at the chitosan concentration of 1.5 wt%, the carnauba wax concentration of 8 wt% and temperature of 85 °C. After 10 g/m2 of chitosan/carnauba wax emulsion was applied to the paper surface, the oil and water resistance of the paper was significantly improved. The experimental results of kit rating value, oil contact angle, Cobb60 value and water contact angle were 9.5 ± 0.6, 86.6 ± 2.1°, 8.90 ± 1.62 g/m2 and 123.5 ± 2.6°, respectively. The application of chitosan/carnauba wax emulsion coating on papers provided a significantly lower water vapour transmission rate (WVTR, 78.45 ± 18.92 g/m2·24 h) and oxygen transmission rate (OTR, 94.26 ± 20.21 g/m2·24 h) as compared to the original paper, which met the needs of strawberry packaging.