A facile process for fabrication of environmentally safe superhydrophobic surfaces

Superhydrophobic coatings have opened new vistas in the field of self-cleaning surfaces by having improved performance, robustness and preservation of cleaning agents including water. Presently, fluoropolymers are extensively explored and used for this purpose. However, the major drawback accompanying fluoropolymers is formation of environmentally persistent and toxic compounds, viz. PFOA (perfluorooctanoic acid) and PFOS (perfluorooctanesulfonic acid) on their degradation raising concern on their use. In the present study, an effort has been made to develop a facile process by using an environmentally safe material. A simple dip coating technique is reported to fabricate superhydrophobic surface. SiO₂ nanoparticles of size 25–30 nm, prepared by sol–gel route, were dip-coated on glass substrate in multilayers followed by coating of a surfactant to achieve homogeneity of SiO₂ layers and enhanced binding with subsequent layer of NUVA-2114 [a commercially used fluorotelomer with chemical composition C₂F₆(CF₂CF₂) _n X]. It was observed that SiO₂ nanoparticles and sodium dodecyl sulfate (SDS) surfactant exhibit a synergistic effect on interface stability at optimized SDS concentration. A water contact angle of 152° is achieved. The established method is simple, scalable, environmentally safe and cost-effective.