Food-Safe Chitosan–Zein Dual-Layer Coating for Water- and Oil-Repellent Paper Substrates

Coated paper substrates are used for a wide range of applications. The biggest challenge that remains unsolved with regard to coated paper is its recyclability. Herein, we report a unique approach that relies on 100% biobased and biodegradable food-safe materials for water- and oil-resistant papers. A 35-liner paper was coated with an oil-resistant chitosan solution and subsequently by a hydrophobic zein solution. The resultant chitosan–zein-coated paper showed remarkable water resistance (Cobb 60 value of 4.88 g/m2) and oil repellency (kit rating 12/12). Scanning electron microscopy (SEM) analysis was used to determine the changes in the surface texture of the paper before and after coating treatment. The excellent mechanical properties of the coated paper were retained after the coating treatment. In addition, the pulp was recycled from the chitosan–zein-coated paper to validate the recyclability of this novel approach.