Preparation And Strengthening Of Durable Self-similar Cu-based Superhydrophobic Materials

Metal materials have an irreplaceable position in industrial and agricultural production as well as real life.They are one of the most widely used materials.Among them,copper and its alloy have become one of largely consumed metals in industrial production and real life due to their high thermal conductivity and electrical conductivity.However,the mechanical properties and service properties are easily impaired due to the corrosion of copper,and which greatly hinder the wide application of copper and its alloy.Inspired by the phenomenon of superhydrophobicity in nature,the researchers have explored a variety of methods for preparing artificial superhydrophobic surfaces in order to improve the performance of copper and expand its application range.However,the application and development of superhydrophobic surfaces in real life are limited to some extent as a result of the poor stability and durability of most artificial superhydrophobic surfaces.Therefore,how to prepare superhydrophobic surfaces with long-term durability it is a close interest topic to researchers at home and abroad.In this study,Cu-based superhydrophobic materials were prepared by a simple and environment-friendly method,and the surface wettability,phase structure,chemical structure,surface morphology,and compressive strength of the resultant materials were examined and characterized.Meanwhile,the long-term durability,self-cleaning,self-similarity and regenerability of Cu-based superhydrophobic materials were investigated,and then the mechanism was explored in detail.The main work is as follows:?1?Preparation and strengthening of Cu-based superhydrophobic materials:The Cu-based superhydrophobic materials were constructed by chemical oxidizing the copper powder and then hydrophobization modifying with HDTMS.The resultant materials have a contact angle of 153.1°and a roll angle less than 5°.In addition,the strength of the Cu-based superhydrophobic materials was improved by the acid etching and strengthening.The obtained Cu-based sample has strong water repellence,and the compressive strength can reach 60 MPa.The phase structure and chemical structure of copper powder under different processing steps were examined by XRD and FT-IR.The results show that two oxidation products as CuO and Cu?OH?₂ are produced for the copper powder after oxidation.Meanwhile,the long hydrophobic alkyl chains are assembled onto the surface of the copper powder.The surfaces morphology of the Cu-based sample was observed by scanning electron microscope,and results show that the surfaces have micro-and nano-scaled rough structure.Compressive performance test shows that the strength of the reinforced sample is much higher than that of the unreinforced sample.?2?Long-term stability of Cu-based superhydrophobic materials:The various aqueous liquid droplets applied on Cu-based blocks present spherical shape,indicating that the superhydrophobicity of the material is universal.The change of surface wettability upon UV irradiation,different pH droplets,and ten month placement was investigated,and results show that the Cu-based superhydrophobic materials have good UV resistance,acid/base resistance,and storage stability.?3?Self-cleaning performance of Cu-based superhydrophobic materials:The rolling angle at the Cu-based superhydrophobic blocks is quite small.The water droplets applied onto the sample surfaces can roll easily and can carry away the simulated pollutants?such as chalk ash?.Therefore,the surface of the Cu-based superhydrophobic blocks can always keep clean,indicating the resultant Cu blocks have excellent self-cleaning performance.?4?Regenerability and self-similarity of Cu-based superhydrophobic materials:The regenerability and self-similarity were examined by evaluating the wettability after destroying the samples by finger pressing,vegetable oil-polluted,abrasion,etc,and polishing again.Results show that the freshly-exposed surfaces exhibit the superhydrophobicity as usual.In addition,when the sample was broken,it can be observed that the inside of the Cu-based sample had the same structure and wettability as the surface.The tests above show that Cu-based superhydrophobic materials have regeneration and self-similarity.The above research indicates that the preparation of superhydrophobic materials with self-similarity in texture and composition both externally and internally is one of the effective means to improve the long-term durability of superhydrophobic surfaces.This provides a new direction for designing long-term superhydrophobic materials that can be applied in industrial and agricultural production.