Bio-based waterproof and oil-repellent coatings for paper packaging: Synergistic effect of oleyl alcohol and chitosan on performance enhancement

Abstract

Compared to petroleum-based plastics, paper-based materials are biodegradable and renewable, effectively easing resource overconsumption and environmental pollution issues. However, their poor water and oil repellency restricts applications in food packaging. Adding water and oil repellents can enhance paper's barrier properties, but traditional fluorine-containing coatings pose health risks like biotoxicity, accumulation, and migration, leading to global regulatory restrictions. Thus, developing green, biodegradable, bio-based water and oil repellent coatings is the future trend. In this study, taking advantage of the high reactivity of cyanuric chloride (TCT), a chitosan-derived coating (CHI-g-OA₂) with a double hydrophobic chain structure was successfully constructed. The formula for the preparation was optimized by the response surface method. This “molecular modification” strategy, which grafts hydrophobic oleyl alcohol chains onto chitosan molecular chains to successfully construct a hydrophobic barrier, effectively solves the problem where competitive hydrogen bonding disrupts the dense hydrogen bond network formed within and between chitosan molecules, leading to significant attenuation of barrier performance. It also achieves the synergistic improvement of the material's waterproof and oil-repellent properties while retaining the original oil and gas barrier function, which meets the standard for food packaging materials. In addition, the tensile strength of the coated paper has been increased, showing good mechanical and thermal stability.