Oil- and Water-Resistant Coatings for Porous Cellulosic Substrates

Abstract

Water-and oil-resistant materials are useful for many applications, but turning polar and porous cellulosic substrates such as paper, corrugated board, cardboard, and fabrics into a water-and oil-resistant materials is very challenging. Herein, we report an innovative method for fluorine-free water-and grease-resistant surface fabricated from a fully porous cellulosic substrate. A chitosan coating was applied to fill the pores of the paper, followed by a polydimethylsiloxane (PDMS) coating to render paper water and oil resistant. A response surface methodology (RSM) was applied to optimize the concentrations of chitosan and PDMS to obtain the desired water-and oil/grease-resistant properties. Paper coated with a load of 8.6 wt % chitosan and 2.2% PDMS showed an excellent grease/oil kit rating value of 12/12 (maximum fat resistance) as well as excellent water resistance (water contact angles of 95.2°). The coating is robust, as confirmed by solvent extraction tests of the coated paper. This coating approach was also successfully demonstrated for paperboard. Because of the simplicity of the coating application method and fluorine-free coating ingredients, these coatings will find many applications in the real world related to paper, corrugated board, cardboard, and fabrics.

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

“…This considerable improvement in the oil resistance can be associated to the low surface energy created by PDMS and the masking of pores by PVOH and chitosan. 12 Also, an increase in the concentration of PVOH in the PVOH/chitosan-g-PDMS papers was found to improve the kit rating which is due to better masking of the pores owing to thicker coatings. 23 For example, it was also observed that for 0.5 wt% PVOH concentration, the kit rating for the volume ratio of 90P:10CP was 3.5/12, whereas that for the volume ratio of 60P:40CP was 5/12, which indicates that, increase in the amount of chitosang-PDMS in the overall coating solution improves the oil resistance of the coated papers.…”

“…9 To address the above challenges, our group is actively working towards developing plastic-free, PFAS-free, costeffective water-and oil-resistant surfaces. [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.…”

“…[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. This motivated us to pursue a costeffective approach using blends of chitosan-g-PDMS and polyvinyl alcohol (PVOH).…”

Fabrication of oil‐ and water‐resistant paper without creating microplastics on disposal

“…Polysaccharides and proteins are biodegradable in nature and their use for paper coating is very appealing, but they are hydrophilic in nature and hence they have poor water resistance 10,19–21 . Recently, our group has developed chitosan‐ graft ‐silicone oil coatings for paper with good water and oil repellent properties 22–26 . Silicone oil was chosen because of its relatively food safe nature and exceptional water and oil repellent properties that have been demonstrated in various coatings 27–34 .…”

Dual-Layer Approach toward Self-Healing and Self-Cleaning Polyurethane Thermosets

“…However, due to the harmful and persistent nature of fluorine-containing compounds in the environment, fluorine-free alternatives are highly desirable. In this regard, PDMS has recently been employed by our group and others to introduce self-cleaning properties [38,39,40,41,42,43,44,45]. In a recent study, polydopamine (PDA) coated fabric was treated with stearic acid to impart excellent water repellency.…”