Stable Bionic Superhydrophobic Coating Surface Fabricated by a Conventional Curing Process

Abstract

In nature, various plants, including the lotus leaf, exhibit the unusual phenomenon of superhydrophobicity. The surfaces of these leaves usually have binary structures on the micrometer and nanometer scales, resulting in low water sliding angles (WSAs) and high water contact angles (WCAs) up to 162°± 5°. This is because air can be trapped between the droplets and the wax crystals at the plant surface, which minimizes the real contact area.[1] Water repellency is important in daily life as well as in many industrial and biological processes, such as the reduction of frictional drag on ship hulls, antiicing and self-cleaning.[2]Artificial superhydrophobic surfaces with WCAs larger than 150°and very low WSAs have been prepared by various processing methods through controlling the surface topography of expensive hydrophobic materials, using techniques such as etching and machining. [3][4][5][6] However, these methods for creating superhydrophobic surfaces typically use expensive materials or severe conditions, limiting the application of superhydrophobic surfaces. Bionic polymer surfaces with superhydrophobicity have been prepared by a one-step casting process under ambient atmosphere. [7,8] Erbil et al.[7a] employed a very simple method involving solvent evaporation to fabricate a superhydrophobic surface, which provides a new, promising method to fabricate artificial superhydrophobic surfaces on polymer surfaces. However, it is well known that the various superhydrophobic surfaces were only fabricated on glass substrates at room (or low) temperature, and the cohesion between the polymer coatings and glass substrates was weak, allowing the films to be easily scraped off, and no longterm stability over a wide pH range was achieved in comparison with the high-temperature process. These superhydrophobic surfaces cannot withstand low-to-high temperature changes. Conventional fluorine-polymer hydrophobic coatings have been used as antisticking and antifouling surfaces and to reduce drag and flow noise for long time because of their low surface free energy. [9,10] However, the ordinary fluorine-polymer hydrophobic surfaces have WCAs of merely 110°-125°, i.e., they are not superhydrophobic.[10e]In this Communication, we demonstrate that bionic poly-(tetrafluoroethylene)/poly(phenylene sulfide) (PTFE/PPS) superhydrophobic coatings with long-term stability, high cohesional strength, and resistance to temperature change can be prepared by a simple, inexpensive, and conventional curing process. A superhydrophobic surface with a porous network, micrometer-nanometer-scale binary structure (MNBS) roughness, and the lowest surface energy hydrophobic groups (-CF 3 ) was fabricated using commercially available PTFE and PPS on stainless steel and engineering materials. The fabrication of a superhydrophobic coating by our conventional curing process is reported in this Communication for the first time to our knowledge. It is expected that this technique will make it possible to prepare superhydrophobic engineering materials with new ...

Preparation of a superamphiphobic surface on a common cast iron substrate

“…8,9 This phenomenon renders materials with superhydrophobic surfaces a self-cleaning property. The self-cleaning property and the limited contact areas between the solids and the water droplets make the superhydrophobic surfaces preferable for many industrial and biological applications, such as antibiofouling paints for boats, 10 snow-repelling for antennas and windows, 11 self-cleaning windshields for automobiles, 12 reduction of frictional drag on ship hulls, 13 microfluidics, 14 and stain resistant textiles. 15 Based on their properties, artificial superhydrophobic surfaces have attracted much attention in the past several years, and many methods of fabricating superhydrophobic surfaces, such as the solution method, 16,17 sol-gel method, 18-20 plasma polymerization, 21,22 selfassembly method, 23 template method, 24 surface oxidation method, 25 and other methods [26][27][28][29][30] have been proposed.…”

Ordered water monolayer at room temperature

“…Several factors, such as temperature (Wang et al 2008b), surface roughness (Luo et al 2008;Koishi et al 2009;Yong and Zhang 2009;Gao 2004) and surface polarity (Wang et al 2011(Wang et al , 2009Giovambattista et al 2007Giovambattista et al , 2009Yang et al 2005;Meng et al 2006), could affect the wetting behavior of water molecules on surfaces. In particular, surface polarity has been recognized as playing a crucial role in determining the behavior of water at hydrated interfaces.…”

Fabrication of hierarchical structures on alumina plate and its nonwetting property

“…Since the water droplets are unable to slide on the surface, a surface with high adhesion is observed [19]. In contrast, in Cassie's state (Figure 6(b)), the water droplets adopt a nonwet-contact mode on solid surfaces and can roll off easily due to their low adhesive force [20]. It is believed that the water droplets on the Al plate are in Cassie's state described by the Cassie-Baxter equation [21] cos r ¼ f 1 cos À f 2 , where f 1 and f 2 are the fractions of solid contact area and air contact area with water, respectively (i.e.…”