A Cavitated-Ridged Reentrant Coating System for Fabrication of Robust, Fluorine-free Superomniphobic Surfaces

Low surface energy finishing agents, particularly perfluoroalkyl compounds containing long or short fully fluorinated carbon chains, have been widely used for liquid-repellent modification of fabrics. However, fluorinated chemicals are harmful to environment and human health. It remains a formidable challenge to develop fluorine-free super-liquid-repellent coatings. Herein, a fluorine-free superomniphobic coating is provided with rational cavitated-ridged reentrant surface design that resembles the cavitated and ridged reentrant cuticle structure of a springtail, by hydrolysis polycondensation of octadecyl trichlorosilane (OTS) followed by incubation in water vapor. The obtained superomniphobic coating is composed of both continuous micro-scale cavitated ridges with high porosity and nano-scale open cavities with sharp edges. As a result, the treated fabrics showed outstanding super-repellency to liquids with surface tensions between 27.8 and 72.8 mN·m^-1. This superomniphobic coating technique has excellent adaptability and can be used for various substrates. The coating also exhibited long-term stability against various physical/chemical damages, e.g., peeling, the impact of high the number water jet, long-term UV irradiation, liquid nitrogen, strong acid/alkali attacks even for 98% H₂SO₄ and saturated NaOH, ensuring the long term stability and reliability. This work may promote the development of environment-friendly and fluorine-free coatings for practical applications.