Fabrication and Water Collection Performance of Biomimetic Patterned Surface with Hybrid Wettability

Freshwater is an indispensable resource for human survival, but it is exacerbated by uneven distribution, wanton waste and pollution of water resources. Billions of people around the world are currently facing severe water scarcity, a problem that remains an unanswered problem affecting life in arid and semi-arid regions. The back of the beetle has a hybrid wettability patterned gradient consisting of a series of hydrophilic patterns distributed on the hydrophobic surface. The mist condenses in the hydrophilic area of the beetle's back, sheds over time into the superhydrophobic area, and then enters the beetle's mouth. Inspired by it, the surface with the hybrid wettability gradient prepared in this paper is different from the beetle surface in that the pattern of this sample is composed of a series of hydrophobic pattern groups distributed on the hydrophilic surface. The pretreated copper mesh was placed in 1.5 mol/L sodium hydroxide solution and 0.05 mol/L ammonium persulfate solution for 30 min, and its surface was uniformly covered with a layer of copper hydroxide nanoribbons. The copper hydroxide on the surface presented a three-dimensional rough structure, mainly weed-like at the tip, forming a hydrophilic surface with a contact angle of 60°; Subsequently, 0.05 mol/L n-dodecyl mercaptan (96%)/ethanol solution was selectively brushed on the hydrophilic surface of copper hydroxide, resulting in the surface morphology of the brushed area changing from tip weed-like to round-ended aquatic grass, forming a superhydrophobic region with a contact angle of 150°, and a wettability surface with biomimetic hybrid patterned was prepared. The wettability, surface topography and chemical composition of the samples were analyzed by contact angle measuring instrument, scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The mist water collection device was built on the basis of the wettability surface with biomimetic hybrid patterns, which simulated the humid environment to characterize the water collection efficiency of the sample and the stability of the sample in different harsh environments. In the water collection process, the collected water droplets were intercepted by the hydrophobic area, and then converge in the hydrophilic area of the vertical striped leaf vein path to form a hydrophilic leaf vein area, and with the passage of water collection time, a leaf vein-like water film was formed, which reduced the time for water droplet transportation, collection, and dripping. The construction of hydrophobic patterns on the hydrophilic surface provided a new idea for subsequent experiments. Compared with the original surface, the hydrophilic surface and the superhydrophobic surface, the water collection rate of the prepared bionic mixed wetting pattern surface was increased by 146%, 111% and 61%, respectively, and the water collection rate was inversely proportional to the size and spacing of the pattern. It had nothing to do with the pattern shape. In addition, after ultraviolet irradiation and 100 °C heat treatment, the biomimetic patterned surface with hybrid wettability still maintained stable water collection performance. This showed that the function of the sample would not be affected when used outdoors for a long time, thus providing a solid basis for the prepared sample to collect water efficiently in the actual environment. The sample has the advantages of simple preparation, low cost, high efficiency and durability, and has a potential application prospect in atmospheric water collection, which is expected to provide a solution to the shortage of water resources. © 2024 Chongqing Wujiu Periodicals Press. All rights reserved.