Preparation of a robust cellulose nanocrystal superhydrophobic coating for self-cleaning and oil-water separation only by spraying

Cellulose nanocrystal (CNC) is usually prepared by acid hydrolyzation of cellulose mainly coming from wood and crops such as cotton, flax, and hemp. A robust superhydrophobic coating was successfully created by two-step spraying method, in which a commercial spray paint is used as adhesive and first sprayed onto the substrates, followed by spraying modified CNC onto the adhesive. The resulting coatings on the wood and glass slide show excellent superhydrophobicity with a water contact angle (WCA) of 163 degrees, outstanding self-cleaning, and high mechanical strength. In addition, the stainless steel mesh coated with adhesive and hydrophobic CNC is efficient and reusable for oil-water separation and shows high resistance to chemical corrosion and UV radiation. This CNC superhydrophobic coating can be applied on unlimited substrate surfaces only by spraying and is beneficial to promote industrial use value of wood and crops.