Simple spray deposition of a water-based superhydrophobic coating with high stability for flexible applications

Superhydrophobic coatings have attracted significant attention due to their wide potential applications. However, the practical applications of the present artificial superhydrophobic coatings are not only hindered by their environmentally hazardous components, containing fluorinated materials and pungent organic solvents, but also by their poor material stabilities. Herein, a robust water-repellent organic-inorganic composite coating based on an aqueous dispersion was developed using a non-fluorinated material system consisting of a waterborne silicone-acrylic copolymer (SAC) and silica sol. Uniquely, the as-prepared SAC containing acid functional groups was first ionized in an alkaline environment, followed by introduction of the silica precursor into the SAC to generate the silica sol in situ. The abovementioned non-fluorinated material system favors the application of the simple spray technique for the superhydrophobic coating (157.7°) deposition, which can be flexibly employed on various substrates. The resulting composite coating, in which strong micro- and nano-scale roughness structures are embedded in the layer matrix, can withstand at least 200 abrasion cycles while retaining its superhydrophobicity. Moreover, the composite coating also shows significantly high resistance to acid/base, organic solvent, UV photodegradation (UVA light illumination for 96 h) and high-temperature heating (400 °C for 80 h). Furthermore, this environmentally friendly coating can be easily applied in the self-cleaning (in either air or oil environments) and oil/water separation fields.