Effects of chemical composition on the hydrophobicity and antifouling performance of epoxy-based self-stratifying nanocomposite coatings

Abstract

Inspired by nature, the superhydrophobic surface has great potential for application in the field of antifouling due to its excellent fouling resistance. Nanocomposite coatings are an economical way to fabricate superhydrophobic surfaces by controlling the surface chemical composition and topography. However, the available open literature assessing the chemical composition effects on hydrophobicity and antifouling performance is rare. In this study, epoxy-based nanocomposite coatings with various wettability were fabricated by using the air-spray technique. The element distributions of the coatings at different depths were characterised by EDS and XPS. The results showed that the top coating surfaces of ER-F, ZnF40-1:5, and ZnF40-1:9 were enriched in F and Si elements, evidencing the self-stratifying. And by reducing the solid surface free energy, the hydrophobicity of ER-F, ZnF40-1:5, and ZnF40-1:9 was significantly improved. And the coating ZnF40-1:9 achieved super-hydrophobic. Based on the Young's equation and the “equation of state for the interfacial tensions”, it was found that the effect of solid surface free energy on CAH was greater than that on WCA due to the greater coefficient of the variable. The superhydrophobic coating ZnF40-1:9 shows great antifouling performance against marine diatom P. tricornutum and its antifouling rate is up to 94.1%. By reducing the surface free energy, the hydrophobicity of nanocomposite coatings can be improved significantly, consequently improving the antifouling performance effectively. These findings might provide insight into developing superhydrophobic nanocomposite coatings to inhibit biofouling.