An Efficient Substrate-Free Method of Producing SiO₂-Based Nanoparticles for Superhydrophobic Applications

Abstract

We report on the preparation of SiO 2 -based nanoparticles readily available for superhydrophobic applications. In contrast to usual approaches, our process is substrate-free and based on electrostatic adsorption of small SiO 2 particles onto large SiO 2 cores with the aid of poly(diallyldimethylammonium chloride) followed by calcination and chemical modification with trichlorododecylsilane. The as-prepared nanoparticles are in powder form and exhibit stable superhydrophobic behavior at room temperature because of the unique combination between the hierarchical raspberry-like structure and low surface energy. If properly stored, the nanoparticles retain their functional properties for several months.

Influences of Heat Treatment, Particle Arrangement, and Binder Addition on the Mechanical Robustness of Structurally Colored Coatings Formed with Monodisperse SiO2 Spheres

“…The PDDA remained in the film before heat treatment, but after heat treatment at 600 °C or higher, it was burned out and no longer remained in the coatings prepared by means of cathodic EPD using PDDA. [ 42 ] However, in films prepared using the Mg 2+ salt, Mg components were present regardless of whether or not the film was heat‐treated, and they acted as a binder. Figure shows photographs of the coating films after they had undergone mechanical robustness testing.…”