Preparation of Stable Superhydrophobic Coatings on Complex‐Shaped Substrates

Abstract

Superhydrophobic surfaces have potential applications in many fields, but are seriously hindered by their complicated preparation methods and low mechanical stability. Thus, novel strategies for efficient preparation of robust superhydrophobic surfaces on various substrates are highly desired. Here, the preparation of stable superhydrophobic coatings on complex‐shaped substrates by the combination of phase separation and dip‐coating is reported. The coatings show excellent superhydrophobicity for both water and other frequently used liquids, superior impalement resistance, and high stability. Moreover, this strategy can make diverse complex‐shaped substrates superhydrophobic, outperforming the conventional methods. The strategy also has many other merits such as simple, fast (<1 min), scalable (50 kg stock solution per batch and large superhydrophobic samples), and low cost (7.8 CNY m−2 or 1.2 UDS m−2). The superhydrophobic coatings may find applications in many fields including anticorrosion and antiicing, and the findings here will inspire straightforward preparation of robust superhydrophobic coatings on diverse substrates.

Robust Superhydrophobic Surfaces via the Sand-In Method

“…The weathering tests, including the heating test and UV radiation, were also carried out to determine the stability of the PTFE–LIGF substrate. The decomposition temperature of the LIGF is ∼660 °C, which is much higher than that of the oil lubricants and common organic coating, such as perfluoroalkyl or fluoroalkyl-silane moieties. ,− The good thermal performance of the LIGF results in the thermal stability of the PTFE–LIGF substrates. The heating treatment can cause the slight decrease of the apparent CA and the increase of CA hysteresis after 24 h (Figures f and S33).…”

“…From −20 to −35 °C, the water droplet reaches ∼0 °C or below once in contact with the normal surface and forms a layer of ice . For the flat substrate, the freezing of a water droplet starts from the spontaneous nucleation at the solid–liquid interface, and subsequently, the ice nuclei grow from bottom to top . The substrate, after sand-in using LIGF powders, shows a larger surface roughness, which can trap an air layer between the water droplet and substrate.…”

“…In particular, doubly re-entrant microstructures can resist almost any liquid, regardless of the intrinsic wettability of the surface materials. , However, there is a trade-off between durability and superhydrophobicity . Chemical functionalization has focused on effective building blocks for the surface coating, such as perfluoroalkyl or fluoroalkyl-silane moieties. − Common methods include chemical grafting, electrochemical methods, , and sol–gel methods. , Previous work has shown that a flat surface covered with −CF 3 groups has the lowest surface energy (∼6 mN m –1 ) . Since the surface energy of water is ∼72 mN m –1 , these chemically modified surfaces show excellent water repellency.…”

Enhancing the Output of Liquid–Solid Triboelectric Nanogenerators through Surface Roughness Optimization

“…Electrochemical deposition and the sol–gel method were used to reduce the surface free energy. Functional groups with strong electron absorption capacity can enhance the surface charge density of solid materials, improving the output performance of LS-TENGs. − The electrical properties of the liquid also influence the output of LS-TENGs. It is essential to examine the ionic type, ionic concentration, liquid pH, dielectric constant, polarity, liquid type, viscosity, and surface tension of the liquid to understand the impact of the liquid material on the electrification of liquid–solid contact.…”

Facile Preparation of Robust Superamphiphobic Coatings on Complex Substrates via Nonsolvent-Induced Phase Separation

“…To sum up, in spite of great potential, robust superamphiphobic coatings applicable to complex substrates are yet to be developed, especially via simple and efficient approaches. Here, on the basis of our previous work about superhydrophobic coatings on complex-shaped substrates, 36 we report a simple method for preparing superamphiphobic surfaces with good durability on various substrates regardless of their shapes, surface microstructures, chemical compositions, etc. First, a uniform stock suspension is prepared by nonsolvent-induced phase separation of a mixture containing fluorinated silica (FDsilica) nanoparticles and a silicone-modified polyurethane (Si-PU) adhesive.…”