Uniting Superhydrophobic, Superoleophobic and Lubricant Infused Slippery Behavior on Copper Oxide Nano-structured Substrates

Abstract

Alloys, specifically steel, are considered as the workhorse of our society and are inimitable engineering materials in the field of infrastructure, industry and possesses significant applications in our daily life. However, creating a robust synthetic metallic surface that repels various liquids has remained extremely challenging. The wettability of a solid surface is known to be governed by its geometric nano-/micro structure and the chemical composition. Here, we are demonstrating a facile and economical way to generate copper oxide micro-nano structures with spherical (0D), needle (1D) and hierarchical cauliflower (3D) morphologies on galvanized steel substrates using a simple chemical bath deposition method. These nano/micro textured steel surfaces, on subsequent coating of a low surface energy material display excellent superhydrophobic, superoleophobic and slippery behavior. Polydimethylsiloxane coated textured surfaces illustrate superhydrophobicity with water contact angle about 160°(2) and critical sliding angle ~2°. When functionalized with low-surface energy perfluoroalkylsilane, these surfaces display high repellency for low surface tension oils as well as hydrocarbons. Among them, the hierarchical cauliflower morphology exhibits re-entrant structure thereby showing the best superoleophobicity with contact angle 149° for dodecane. Once infused with a lubricant like silicone oil, they show excellent slippery behavior with low contact angle hysteresis (~ 2°) for water drops.

Wettability on Different Surfaces

“…In fact, numerous investigations have been devoted to the wettability on different surfaces, particularly for the surfaces inspired by Nature Mother [18][19][20][21][22][23][24][25][26]. Paxson et al [27] fabricated a surface with the hierarchical textures initiated by lotus leaves and revealed the relevant mechanism of the variation or evolution of the adhesion force per unit length of the projected contact line distributed on natural textured surfaces.…”

Bioinspired Slippery Zinc Phosphate Coating for Sustainable Corrosion Protection

“…The phase angle sharply decreased in the middle frequency domain after immersion for 4 weeks for the SZP coating, which demonstrated that the anticorrosion performance was decreased with a long immersion time. That likely due to the lubricant being partly removed from the substrate because of the positive spreading coefficient of lubricant in aqueous solution, and part of the lubricant may be dissolved in the water limitedly given its relatively low viscosity, making the lubricant layer thinner. − Thus, the corrosive ions can penetrate into the coating/metal interface easier from the tip or the edge of the phosphate coating and result in the decrease of phase angle . Also, the barrier resistance was also fitted by the same equivalent circuit in Figure (c).…”

“…It can be found that the E corr shifted to negative position after immersion in NaCl solution, indicating that the corrosion would occurs easily. However, with the increasing immersion time, the E corr of the coating had a slight rise, a thin lubricant-water layer would be generated between the coating and solution, and thus the corrosion potential increased. The I corr of samples were calculated and displayed in Figure (b).…”

Facile Fabrication of Slippery Lubricant-Infused CuO-Coated Surfaces with Different Morphologies for Efficient Water Collection and Excellent Slippery Stability

“…Sample-2 with nanoneedles-assembled structures seems to have decreased lubricant thickness than Sample-1, which is also reflected in the increased SAs. The lubricant trapped in the nanolamella-assembled structures is hard to be removed . The CAs and SAs of various oils including glycerol (64 mN/m), formamide (59.13 mN/m), diiodomethane (50.1 mN/m), ethylene glycol (47.7 mN/m), and dimethyl sulfoxide (43.54 mN/m) are shown in Figure b, which exhibited favorable liquid repellency of as-prepared CuO LISs.…”