Chitosan–Graft–Poly(dimethylsiloxane)/Zein Coatings for the Fabrication of Environmentally Friendly Oil- and Water-Resistant Paper

Abstract

Excessive use of synthetic nondegradable polymers has led to the proliferation of microplastics in the oceans as well as polluted landscapes. Herein, we report a new sustainable approach for the development of oil- and water-resistant paper. Chitosan–graft–poly­(dimethylsiloxane) (CHI–g–PDMS) copolymers were prepared by the reaction of poly­(dimethylsiloxane) (PDMS) with chitosan. The CHI–g–PDMS graft copolymer was characterized by 1H nuclear magnetic resonance (NMR) analysis. Zein, a coproduct of the bioethanol industry, was blended with CHI–g–PDMS in a water/ethanol solution and subsequently applied as a coating on an unbleached Kraft paper. The coated paper substrates were evaluated for their oil resistance via kit rating and oil contact angle measurements, while the water resistance was determined via Cobb60 value and water contact angle measurements. In addition, the pulp was successfully recovered from the coated paper. Scanning electron microscopy (SEM) analysis was used to investigate the variation in the texture of the paper before and after the coating treatment. Thanks to the efficient pulp recovery and the biodegradable nature of the coating ingredients (chitosan and zein), this novel water- and oil-resistant paper will positively impact the environment by offering potential replacements for single-use plastic applications, and will thus help to minimize ocean microplastics and the burdens placed on landfills.

Oil‐ and water‐resistant paper substrate using blends of chitosan‐graft‐polydimethylsiloxane and poly(vinyl alcohol)

“…[10][11][12][13][14][15] One of the key focus is the use of benign polydimethylsiloxane (PDMS) as an alternative to PFAS because PDMS is known for imparting water and oil repellent properties while still acceptable for food contact applications. [16][17][18][19][20][21][22] In a recent breakthrough study, we reported the fabrication of water-and grease-resistant coating using Chitosan-grafted-PDMS (Chitosan-g-PDMS), and the coated paper was 100% recyclable by washing the coating off. 12 From a practical perspective, chitosan-g-PDMS system is relatively expensive while at the same time, chitosan has a low availability due to complicated purification processes.…”

Chitosan/Montmorillonite Coatings for the Fabrication of Food-Safe Greaseproof Paper

“…Dhwani et al [17] recently reported that the kit rating values of chitosan coated paper and chitosan-graft-sunflower oil coated papers were 12/12 and 8/12, in which the coating loads were 3.6 g/m 2 and 5.6 g/m 2 , respectively. Syeda et al [10] showed that the chitosan coated paper had a kit rating value of 12/12 when the coating load was 6.1 g/m 2 , and the chitosan-graft-polydimethylsiloxane coated paper obtained the eighth grade when the coating load was 9.4 g/m 2 . Zhao et al [18,19] reported that the chitosan coated paper had a kit rating value of 8/12 when the coating load was 9.33 g/m 2 .…”

“…However, the micromolecules of synthetic polymers can migrate from a paper container to foods, which is harmful for human health [ 8 , 9 ]. Using low surface energy chemicals per- and polyfluoroalkyl substrates (PFAS) and silicone oils is another way of improving the oil resistance of paper [ 3 , 10 ]. However, PFAS have a huge threat to human health due to their toxicity and the degradation difficulty [ 11 , 12 , 13 ].…”

Oxygen and water vapor barrier properties of polyvinyl alcohol and zein bilayer‐coated paper

“…6,11 Our group has been active in developing water and oil repellent coated paper as an alternative to plastics. 7,[12][13][14] Recently, we reported polyvinyl alcohol (PVOH)-and zein bilayer-coated paper with good water and grease resistance. 13 PVOH is a biodegradable synthetic polymer, while zein is a biodegradable material that is extracted from corn during bioethanol production.…”