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.