Superoleophobic Surfaces Obtained via Hierarchical Metallic Meshes

Abstract

Hierarchical metallic surfaces demonstrating pronounced water and oil repellence are reported. The surfaces were manufactured with stainless-steel microporous meshes, which were etched with perfluorononanoic acid. As a result, a hierarchical relief was created, characterized by roughness at micro- and sub-microscales. Pronounced superoleophobicity was registered with regard to canola, castor, sesame, flax, crude (petroleum), and engine oils. Relatively high sliding angles were recorded for 5 μL turpentine, olive, and silicone oil droplets. The stability of the Cassie-like air trapping wetting state, established with water/ethanol solutions, is reported. The omniphobicity of the surfaces is due to the interplay of their hierarchical relief and surface fluorination.

Robust icephobic coating based on the spiky fluorinated Al2O3 particles

“…Various experimental techniques were implemented for the study of the stability of the Cassie wetting state 19 . We tested the stability of the Cassie air trapping wetting with the technique enabling establishment of the threshold (critical) value of the surface tension of liquid (denoted γ c ) at which onset of the Cassie-Wenzel transition is registered, which was used successfully by a number of research groups for this purpose [36][37][38] . Droplets of aqueous ethanol solutions were placed on the reported surface, and the apparent contact angle was taken.…”

“…The red point in Fig. 6 indicates the onset of the wetting transition [36][37][38] . It is recognized from Fig.…”

Growth of hierarchical gold clusters for use in superomniphobic electrodes

“…[20][21][22] Various methods including spray coating, 23,24 multiple spin coating, 25,26 and chemical etching 27,28 have been devised to fabricate hierarchical textures on different substrates like polymers, 29 glasses, 30 and metal wires. 31 However, until now, there have been very few studies on the creation of micro/ nano hierarchical structures using wet-chemical methods to obtain metallic omniphobic surfaces. Also, considering that electrode contamination results in electronic device malfunction, especially in wearable sensing devices, it is important to develop a fabrication technique that creates metal electrodes with protective and omniphobic properties.…”

Tunable superoleophobicity via harnessing the surface chemistry of UV responsive titania coatings

“…14 These specially engineered surfaces can support the low surface tension liquid drops very easily by trapping more air into the space between the roughnesses under the droplet than the simple rough surface. In recent years there has been an avalanche in research studies focusing on the creation of the reentrant structured roughness using various methods like dry anisotropic etching, 15 chemical wet etching, [16][17][18] electrochemical etching, 19 spray coating, 7,20,21 and electrospun 22 etc. Noticeably, all these surfaces show constant wettability (superoleophobicity); tunable wettability for oils would offer potential promise to design and fabricate advanced materials for applications like microuidics, oil/water separation etc.…”