Oil- and Water-Resistant Coatings for Porous Cellulosic Substrates

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.