One-Pot Preparation of Fluorine-Free Magnetic Superhydrophobic Particles for Controllable Liquid Marbles and Robust Multifunctional Coatings

In this paper, magnetic superhydrophobic particles were prepared by simultaneously coating silica microspheres and modifying 1,1,1,3,3,3-hexamethyl disilazane (HMDS) around the ferric oxide nanoparticles via a one-pot sol-gel process. The effect of the molar ratio of tetraethyl orthosilicate (TEOS) to HMDS on the wettability of superhydrophobic particles (Fe3O4@SiO2/HMDS) was investigated. Various stable liquid marble encapsulated solvents with different surface tensions, pH values, volumes, and temperatures could be obtained by simply rolling them on superhydrophobic particles. The magnetic liquid marbles could be directional transported and fixed-point volatilized. Furthermore, superhydrophobic particles were sprayed onto different surfaces using polydimethylsiloxane (PDMS) as the binder to construct organic-inorganic composite multifunctional coatings by a one-step process. By optimizing the content of Fe3O4@SiO2/HMDS and PDMS in the spraying solution, the prepared coatings showed superior super-hydrophobicity with contact angles of larger than 150 degrees and sliding angles of smaller than 10 degrees. The coated fluorine-free fabric possessed excellent air permeability, tensile strength, and hydrostatic pressure resistance, thus fulfilling the practical wearable requirements. Besides, the prepared fabrics maintained stable water repellency even after withstanding mechanical damages or long-term exposure to severe environments. Moreover, the coated superhydrophobic materials could be applied for the on-demand separation of various oil/water mixtures. In addition, the superhydrophobic fabric presented excellent photothermal conversion performances, showing outstanding anti-icing and accelerated deicing properties. Thus, the prepared nonfluorinated and stable magnetic particles offer potential in the areas of controlled encapsulation and directional delivery and, as building blocks, are promising for the construction of robust, large-area, and multifunctional self-cleaning surfaces.