Study On Fabrication And Properties Of Copper-based Superhydrophobic Surfaces Based On Mercaptan Self-assembly

Many biological surfaces in nature are superhydrophobic,such as the upper surface of lotus leaves,rice leaves,and butterfly wings.Inspired by this,bionic superhydrophobic surfaces have received great attention from scientific research and industry in recent years.Copper,as one of the most important engineering metal materials,is widely used in electrical engineering,mechanical engineering and chemical industry,etc.However,the inherent hydrophilicity of copper limits its application effectiveness and service life in some applications,so superhydrophobic treatment of copper surface is expected to enhance its comprehensive use performance.At present,the processing of copper-based superhydrophobic surfaces is mainly based on surface roughening and low surface energy treatment,among which mercaptan selfassembly is one of the common means of low surface energy treatment,but the influence rule of mercaptan on the substrate surface properties still needs to be studied in depth.To address this issue,this paper investigates the mechanism and law of the effect of two typical mercaptan self-assembly on the surface properties of copper-based materials and realizes the preparation of copper-based superhydrophobic surfaces.The main research contents and conclusions of this thesis are as follows:(1)The mechanism and rules of the influence of dodecyl mercaptan self-assembly on the wettability of copper mesh were investigated,and then the preparation of superhydrophobic-superoleophilic copper mesh(SSCM)was realized by a one-step self-assembly method.The self-assembly reaction between dodecyl mercaptan and copper atoms generates micro-nanostructures on the surface of the copper mesh,while the long alkyl chains can reduce its surface energy,thus enhancing the hydrophobicity of the copper mesh.Experimental results show that a water contact angle of 153.1° can be obtained when the self-assembly time is 2 h.Meanwhile,the copper mesh is superoleophilic(oil contact angle of 0°),so it can be used for the efficient separation of oil-water mixtures(separation efficiency > 97 %)under a variety of complex working conditions.(2)The effect of perfluorothiol self-assembly on the wettability of copper mesh was investigated,and the one-step self-assembly of corrosion-resistant superhydrophobic copper mesh(SCM)was prepared.By analyzing the surface morphology and chemical composition of the copper mesh,the mechanism of wettability transformation of the copper mesh surface during the self-assembly process of perfluorothiophenol was investigated.A superhydrophobic surface with a water contact angle of 153.7° was obtained when the self-assembly time was 1 hour.The corrosion resistance of the superhydrophobic copper mesh was tested with the help of electrochemical corrosion experiments,and the results showed that the superhydrophobic surface formed by the self-assembly of perfluorothiol improved the corrosion resistance of the copper mesh by about 58.9 % compared with the pristine copper mesh.(3)Based on the above results,the effects of different thiol self-assembly on the performance of superhydrophobic copper sheets were investigated.Micro-grooved rough structures were machined on the copper sheet surface using a femtosecond laser,and superhydrophobic surfaces with ultra-low adhesion(contact angle >150°,rolling angle <10°)were obtained with the help of dodecyl mercaptan and perfluorothiol selfassembly.The corrosion resistance of the above two types of superhydrophobic copper sheets was investigated.Electrochemical tests showed that the corrosion resistance of the perfluorothiol self-assembled surface improved by 78.7 %,while the dodecyl mercaptan self-assembled surface improved by 49.7 %,which indicates that the selfassembled superhydrophobic surface of perfluoro-mercaptan composed of long carbon and fluorine chains has better corrosion resistance than that of dodecyl mercaptan composed of hydrocarbon chains.