A Low-Cost and Facile Strategy to Prepare a Waste Fatty Acid/Chitosan-Derived Coating for Paper with Excellent Water and Oil Resistances

The development of cost-effective, fluorine-free coatings with multifunctional barrier properties for paper-based substrates remains a significant challenge. Herein, a stepwise regulation strategy was proposed to balance relationships of the surface structure and coating material, in which a bilayer coating structure was applied to the fabrication of packaging papers. Silica nanoparticles (SiO 2 NPs) were incorporated into chitosan (CS) to improve the structural density of the paper and hydrogen bond cross-linked CS bottom coating via nanoparticle-mediated physical filling and hydrogen bonding, and then a surface layer was constructed by taking advantage of the hydrogen bond interaction between waste monomer acid (MA) and CS. Compared with the uncoated papers, the Cobb 60 value of coated papers decreased from 64.44 g/m 2 to 2.02 g/m 2, and the Kit grade was increased from 0/12 to 12/12. Additionally, the water vapor transmittance rate (WVTR) and oxygen permeability (OP) of coated papers significantly decreased 95.5% and 97.7%, respectively. Particularly, the shelf life of cherry tomatoes was extended from 4 packaging days in uncoated paper to 13 days packaging in CS@SiO 2 NPs/MA-coated paper. This study provides a strategy for the development of low-cost and high-performance sustainable packaging materials with both significant economic and environmental values.