The current open-loop practices employed to render paper substrates water- and oil-repellent for packaging and non-packaging applications have generated ocean pollution and have placed daunting burdens on landfills.
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.
Biodegradable coated paper materials represent one of the most promising alternatives to petroleum-based materials, including plastics and plastic−paper composite materials. Herein, fully biodegradable and food-safe coated paper substrates are reported with excellent water-and oil-resistant properties. The fabrication approach is facile and economical and utilizes a dual-layer coating that is obtained via the application of a base layer comprising polyvinyl alcohol to offer oil repellency and the subsequent application of a zein-based coating as a hydrophobic top layer. The water and oil resistances of the obtained coated paper were evaluated based on their Cobb60 values, water vapor transmission rate, kit rating, and contact angles. The obtained coated paper shows outstanding water-and oil-resistant performance with Cobb60 values below 3.00 g/m 2 and kit ratings reaching up to 12/12. Scanning electron microscopy results validated the absence of any pores on the coated paper. Thermogravimetric analysis was performed to determine the thermal stability along with the coating content of the paper substrate. The closed-loop nature of this approach was validated via pulp recovery from coated paper with benign solvents.
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