A Simple Preparation Method for Hydrophilic/Oleophobic Coatings

This work provides a simple method to prepare a hydrophilic/oleophobic coating, using polyester filter cloth as the substrate, a mixture of three hydrophilic polymers (poly aspartic acid, polyacrylic acid and polyvinyl alcohol) to form the coating, SiO2 with an average particle size of 30 nm to improve surface roughness of the filter cloth, and finally long fluorocarbon chain of perfluorooctyl triethoxysilane is grafted onto the surface by vaccum silanization coupling reaction to obtain hydrophilic/oleophobic properties. The water and hexadecane contact angle of the treated filter cloth is 3o and 99.7o, respectively. A separation efficiency of 98% was achieved in the hexadecane/water separation. Durability test show that the separation efficiency on hexadecane-water mixture remains more than 98% after 20 cycles. The obtained material also presents a strong underwater anti-pollution property when using hexane, rapeseed oil, mineral oil and pump oil as model pollutants. For oils with higher viscosity, the separation efficiency remains above 97%. However, the separation efficiency is ~80% when treating emulsions.