Durable, Self-Healing Superhydrophobic and Superoleophobic Surfaces from Fluorinated-Decyl Polyhedral Oligomeric Silsesquioxane and Hydrolyzed Fluorinated Alkyl Silane

TLDR: Li et al. as discussed by the authors reported a self-healing superamphiphobic surface on anodized alumina by filling the intrinsic pores with a low-surface energy liquid.

Abstract: Super-liquid-repellent surfaces have attracted much attention in both scientific and industrial areas. They are often deemed superhydrophobic or superoleophobic depending on the liquid to be repelled. Superhydrophobic surfaces have a water contact angle greater than 1508. They have interesting nonsticking, self-cleaning, and anti-contamination functions. The emerging applications include separation of oil from water, energy conversion, protection of electronic devices, adjusting cell/substrate adhesion in the biomedical area, and reducing fluid resistance for aquaculture and microfluidic devices. In contrast, superoleophobic surfaces can be rather complicated, but they have great potential applications in antifouling from hazard chemicals and biological contaminants. Although any solid surface can be characterized as superoleophobic as long as its contact angle with an oily fluid is greater than 1508, the surface properties revealed from the contact angle measurement using different contacting oils could be considerably different. For example, a surface that is superoleophobic to certain oily fluids may have lower repellency or even be wettable by other oily fluids of a lower surface tension. It is normally easy to make a surface super-repellent to oils of a high surface tension, but difficult to prepare superoleophobic surfaces against oily fluids that have a surface tension below 35 mNm . Most super-liquid-repellent surfaces have poor durability. Chemical oxidation from exposure to air, a special chemical environment, strong light, or physical rubbing could cause the surfaces to lose their super-repellency permanently. It is imperative to improve the durability for practical applications. Recently, great progress has been made to develop mechanically robust superhydrophobic surfaces and laundering-durable superhydrophobic fabrics. On the other hand, the bioinspired self-healing ability has been proposed to be a promising solution to improve the durability of synthetic superhydrophobic surfaces. Recently, Li et al. reported a self-healing superhydrophobic coating that was prepared by chemical vapor deposition (CVD) of a fluoroalkyl silane on a layer-by-layer assembled porous surface, and self-healing was derived from the reacted fluoroalkyl silane embedded in the rigidly flexible coating layer. Wang et al. also reported the formation of a self-healing superamphiphobic surface on anodized alumina by filling the intrinsic pores with a lowsurface energy liquid. In the recent study, we have also found that fabrics coated with a hydrolysis product from fluorinated-decyl polyhedral oligomeric silsesquioxane (FD–POSS) and a fluorinated alkyl silane (FAS) have a self-healing superhydrophobic and superoleophobic surface and the coating shows excellent durability to acid, UV light, machine wash, and abrasion. Herein, we first report on its novel multiple self-healing ability and durable performance. The chemical structures of FD-POSS and FAS are shown in Figure 1 a. The coating solution was prepared by dissolving FD-POSS in five times its weight of FAS, and the resulting viscous solution was then dispersed in ethanol. After ultrasonication for 30 min, a homogeneous dispersion was obtained. Figure 1b shows the appearance of an FD–POSS/ FAS dispersion in ethanol. Such a suspension was stable at