High‐Temperature Ultrahydrophobic Ceramic Coatings from Surface‐Functionalized MgAl2O4 Nanoparticles

Innovative coatings that can shield functional surfaces from environmental and temperature impact are essential to increase the life time of devices and reduce the maintenance costs. Superhydrophobic ceramic coatings with self‐cleaning properties and stability at high‐temperatures (up to 300 °C) are eco‐friendly alternative to aggressive surface‐cleaning agents. Despite the wide range of possible applications for hydrophobic surfaces, the practical implementation of currently used polymeric fluoro‐silanes is restricted by their low thermal stability, which is an essential figure of merit. Herein, a nonadhesive coating with an exceptionally low surface‐energy (contact angle ≈180°) is developed by chemical conjugation of MgAl 2 O 4 spinel nanoparticles (NPs) with perfluorodecyltrichlorosilane (FDTS). The cross‐conjugation of FDTS and MgAl 2 O 4 is substantiated by condensation reactions between the surface‐rooted hydroxyl groups and chloride ligands of fluorosilane. Compared with the coatings based on pure fluorosilanes, the FDTS@MgAl 2 O 4 core‐shell particles unify optical transparency and high‐temperature stability imparted by spinel reinforcement with the superhydrophobicity induced by FDTS periphery. Addition of TiO 2 NPs to MgAl 2 O 4 sol unifies the ultrahydrophobicity of FDTS@MgAl 2 O 4 with UV‐absorption properties of TiO 2 to produce a new UV‐ and temperature‐resistant ultrahydrophobic coating system.