Study of Oil Dewetting Ability of Superhydrophilic and Underwater Superoleophobic Surfaces from Air to Water for High-Effective Self-Cleaning Surface Designing

Abstract

The superhydrophilic self-cleaning surface can perfectly deal with oil pollution, which cannot be realized by the superhydrophobic surface. This research is designed to study the mechanism of wetting behavior of superhydrophilic coating with different function groups and guide to design a stable self-cleaning surface. We prepare several hydrophilic coatings including nonionic, ionic, and zwitterionic coatings to investigate their self-cleaning performance underwater when they have been polluted by oil in the dry state. The chemical composition, surface roughness, static and dynamic wettability, underwater oil adhesive force, and swelling degree of the coatings are studied to explore their oil dewetting mechanism. The results indicate that the wettability of the coating to water and oil is the key factor to determine the self-cleaning performance. The smooth 3-sulfopropyl methacrylate potassium salt (SA) anionic coating shows the best self-cleaning performance even when polluted by heavy crude oil in the dry state in air. It is also found that in the dry state, the rough hydrophilic anionic surface will lock up the oil in the structures and then lose its self-cleaning ability underwater, whereas the oil droplet can detach from the smooth coating surface quickly. Meanwhile, the superhydrophilic and underwater superoleophobic SA anionic surfaces also exhibit excellent anti-fogging and oil−water separation performance.

Biomimetic Superlyophobic Metallic Surfaces: Focusing on Their Fabrication and Applications

“…superoleophobic surfaces have attracted a great deal of attention due to their broad application prospects in the fields of oil droplet manipulation, anti-biological adhesion, oil-water separation and self-cleaning [12][13][14] . It is well-known that the hydrophilic chemical composition and micro-nano structure are the key to the preparation of underwater superoleophobic surfaces [17,27,34,46,60,121,162,164] . This part will focus on the recent developments in biomimetic superoleophobic metallic surfaces in the water environment.…”

“…As typical special wettability materials, superhydrophobic, superoleophobic, underwater superoleophobic and slippery liquidinfused porous surfaces (collectively referred to as superlyophobic surfaces) are the most widely studied interfaces because of their excellent water-or oil-repellent ability in air or water [8][9][10][11][12][13][14][15][16][17][18][19][20][21] . Up to now, various superlyophobic surfaces have been reported and widely employed in many different fields, such as self-cleaning [22][23][24][25][26][27][28][29][30] , anti-fouling [31][32][33][34][35][36][37][38][39][40] , anti-fogging [41][42][43][44][45][46][47] , anti-icing [48][49][50][51][52][53][54] , corrosion resistance…”

A Fluoride‐Free and Super‐Wetting Functionalized‐Material with pH‐Responsiveness for Controllable Separation of Multiphase Oil/Water Mixtures

“…According to the previous reports, the layered rough morphology and the low surface energy substance are two crucial elements for the preparation of super-wetting materials. [44,45] So as to obtain pH-responsive super-wetting materials, it is critical that the material surface has specific pH-responsive groups. In this article, based on the previous theory, a superhydrophobic fabric with pH-responsiveness was successfully prepared, as shown in the Figure 1.…”

pH‐Responsive Superwettability Surface: The Study of Oil Dewetting Ability from Air to Water on a Rough Surface and Selective Oil‐Water Separation

“…[ 21–23 ] But it is unrealistic to pre‐wet the material in actual conditions and most materials are used in air, which puts high demands on the decontamination ability of the material. According to our previous study, [ 24 ] for the two superoleophilic surfaces with the same chemical composition after oil contamination in a dry state, the smooth surface can quickly desorb oil droplet and achieve self‐cleaning after being placed underwater, while oil droplet is locked in the micro‐structure of rough surface and difficult to desorb. This indicates that rough structure is not conducive to the self‐cleaning of oil pollution.…”

“…And on a smooth surface, the oil layer deforms into a single droplet directly and detaches rapidly. [ 24,29 ] Whether the desorption process on a rough surface is consistent is also unclear.…”