Fabrication of fluorine-free superhydrophobic coatings from montmorillonite with mechanical durability and chemical stability Mengnan Qu , Menghui Xue, Mingjuan Yuan, Jiao He, Ansar Abbas, Yu Zhao, Jiaxin Wang, Xiangrong Liu, Jinmei He Ó American Coatings Association 2019 Abstract In this study, durable superhydrophobic coatings were successfully prepared by modifying montmorillonite with stearic acid and organosiloxane, and this procedure was simple, efficient, and environ- mentally friendly. Different from the previously reported methods, the micro-/nanostructures of the superhydrophobic coatings were constructed by using the abundant natural montmorillonite as the building blocks. The surface topography of the coating was analyzed with a scanning electron microscope, while element compositions and functional groups were characterized by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy, respec- tively. The as-prepared superhydrophobic coatings showed excellent wear resistance, and could maintain their superhydrophobicity after sandpaper abrasion for 180 cm in length. Apart from the superb wear resis- tance, the obtained superhydrophobic coatings also displayed strong acid resistance and anti-UV proper- ties. In addition, the as-coated fabric not only pos- sessed superhydrophobicity and the ability of oil–water separation, but also exhibited excellent fire resistance because of the thermal stability of MMT particles. Notably, the favorable comprehensive performance of the as-prepared coatings was indicative of their poten- tial applications in oil/water separation and some harsh conditions, and as outdoor protective materials. Keywords Superhydrophobic, Wear resistance, Anti-UV, Oil–water separation, Fire resistance Introduction Superhydrophobic surfaces have attracted increasing attention, which can be ascribed to their potential applications, such as self-cleaning, 1–3 antiicing, 4–6 anti- corrosion, 7–9 drag reduction, 10–12 and oil–water sepa- ration. 13–15 To achieve superhydrophobicity, simultaneous control of hierarchical surface topogra- phy and surface chemistry are required. Until now, a variety of techniques have been employed to establish the superhydrophobic surfaces, including chemical vapor deposition, 16 drop casting, 17 electrospinning, 18 electron radiation-induced 19 deposition, and electro- chemical deposition. 20 However, some of these meth- ods are associated with some disadvantages, such as tedious and time-consuming fabrication process, requirement of intricate instruments to construct suit- able rough structures, and demand for post-treatment using expensive and toxic fluorine-containing reagents. To prepare superhydrophobic surfaces, topographical rough microstructures are usually obtained by intro- ducing inorganic nanophase materials, such as silica particles, 21 carbon nanotubes, 22 ZnO nanorods, 23 and clay particles, 24,25 combined with a hydrophobic treat- ment. However, some superhydrophobic surfaces have poor durability in the presence of oil pollution and other factors, making them easily lose their superhy- drophobic properties. Hereby, it is an urgent require- ment to fabricate superhydrophobic surfaces with excellent wear resistance performance. Generally, most artificial surfaces with water repel- lency are quite instable, since the nanocomposites possess high activity and the micro-/nanostructure is readily destroyed. 26–29 To promote the mechanical stability of these superhydrophobic surfaces, various strategies have been formulated to enhance the mechanical properties through introducing polymers or building a multilevel structure, which could weaken the external force to the surface damage. For example, M. Qu (&), M. Xue, M. Yuan, J. He, A. Abbas, Y. Zhao, J. Wang, X. Liu, J. He (&) College of Chemistry and Chemical Engineering, Xi’an University of Science and Technology, Xi’an 710054, China e-mail: mnanqu@gmail.com J. He e-mail: jinmhe@gmail.com J. Coat. Technol. Res. https://doi.org/10.1007/s11998-018-00179-x