Surface modification of anhydrite whiskers and their potential application for durable superhydrophobic coatings

Abstract

Durability issues have been an obstacle for superhydrophobic coating applications for a long time. Here, we report the modification of anhydrite whiskers that can be used for the fabrication of superhydrophobic coatings with high durability. Anhydrite whiskers with core/shell structures are prepared via hydrolysis and condensation processes of tetraethyl orthosilicate (TEOS) followed by silane modification. Modified anhydrite whiskers were examined by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray powder diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results indicate that anhydrite whiskers exhibit an obviously hydrophobic quality after modification, reaching a contact angle of up to 123°. The thickness of the surface modification layer is 10-20 nm. The modified anhydrite whiskers were used to fabricate a superhydrophobic coating. Modified anhydrite whiskers create a rough structure on the glass substrate surface. This roughness develops a Cassie-Baxter regime, enhancing the superhydrophobicity of the coating. The water contact angle of the coating is above 150°. This method is expected to apply to similar materials for the fabrication of durable superhydrophobic coatings.