Facile preparation of Pickering emulsion-based coatings for hydrophobic, oil-resistant, biodegradable green paper-based packaging

The usage of bio-based polymers to construct paper-based functional materials is currently an important topic in the food packaging industry. Nevertheless, the facile and effective construction of packaging paper materials with excellent water and oil repellency, self-cleaning property, biodegradability and recyclability currently faces distinct challenges. In this aspect, we have developed a one-step coating method for preparing hydrophobic and grease-resistant paper basing on templating dichloromethane-in-water (O/W) cellulose nanocrystals-stabilized Pickering emulsions, which contain chitosan (CS) and glutinous rice starch (GRS) in water phase and polylactic acid (PLA) in oil phase. Herein, the greaseproof polysaccharides CS and GRS are served as the coating film matrix, where the hydrophobic PLA is embedded in the form of microspheres. The optimized coated paper with rough surface structure display highly hydrophobic and water barrier properties with the water contact angle of larger than 130° and water vapor transmission rate of 3.57 × 10−10 gm−1s−1Pa−1, outstanding oil resistance with the kit rating of 9.5/12 and self-cleaning performance. Most interestingly, the soil burial test shows the favourable biodegradability of the coated paper. In addition, the pulp can be recycled from the coated paper and then reused to make paper, validating the recyclability of the coated paper. This study provides a new sustainable and universal research strategy for the large-scale preparation of fully bio-based, recyclable, hydrophobic and oil-resistant, self-cleaning, biodegradable paper materials, which exhibit the highly promising applications in food packaging industry.