Studies On The Preparation And Application Of Controlled Wetting Surfaces

Wettability is one of the basic characteristics of solid surfaces,and the control of wettability plays an important role in surface properties and practical applications.In recent years,due to the development of new materials and manufacturing technologies,various special wettable surfaces,such as superhydrophobic,superhydrophilic,and patterned wettable surfaces,have been prepared,which possess potential applications in anti-corrosion,anti-fog,anti-icing,self-cleaning,fluid drag reduction,oil-water separation and water collection,etc.At present,the main methods to prepare and control surface wettability,such as changing the surface microstructure and chemical properties,are restricted in wide application due to either complicated and expensive preparation technology,or poor stability.Therefore,it is of great significance for promoting its application to design a reasonable wettability surface and develop an effective method to control surface wettability,and reveal the mechanism of controlling surface wettability so as to obtain a generalized method to design and prepare wettability surface,further grasp the law of influences the microstructure parameters and chemical properties exerting on wetting state transition and finally accumulate application data.Focusing on the application of different wettability surfaces in the anti-corrosion and water collection process,this thesis probed into the preparation and application of then controlled wettability surfaces.First,taking the preparation of superhydrophobic surface as an entry point,this thesis utilized three different methods to prepare superhydrophobic surfaces based on improving and simplifying the preparation process,and then studied the influence of micro-nanostructures and chemical properties on the wetting characteristics of obtained superhydrophobic surfaces.The hydrophilic surface was further introduced to prepare patterned controllable wettability surface.Finally,the colorization and stability improvement of superhydrophobic surfaces were studied,and the corrosion resistance characteristics tested and analyzed by using the copper,based on which the application of patterned wettability surfaces in the mist water collection system was explored.The main research contents and conclusions are showed in follows:(1)Aimed at the anti-corrosion of metal surface and water collection application,and based on the study of relations between different preparation methods,the operating parameters of each process and the surface microscopic morphologies and wettability,methods of Sol-gel,alkaline solution impregnation and anodization were used to control the wettability of halloysite nanotubes(HNTs),copper and titanium sheets respectively,and superhydrophobic surface and patterned wettability surface were prepared.In addition,the surface microscopic morphologies and chemical composition were detected through surface characterization and test methods to determine the key factors that affect the surface wettability.The results show that the superhydrophobic surface whose wettability is controllable and superhydrophobic-hydrophilic patterned surface can be prepared through controlling the surface wettability distribution and the contact angle based on reasonable optimization of the micro structure and free energy distribution of the surface.(2)Based on the key factors affecting the surface wettability,a new method for preparing colored wear-resistant superhydrophobic surface is proposed for the practical applicability of wettability surface by combining HNTs,cationic dyes and epoxy resin.Bionic superhydrophobic pigment with high contact angle and ultra-low rolling angle was prepared by combining HNTs nanotubes,cationic dyes and organosilane.The bionic superhydrophobic pigment was used as topcoat,and epoxy resin as primer to prepare colored wear-resistant superhydrophobic surface on stainless steel surface by spraying method.Epoxy resin strengthened the adhesion between the superhydrophobic surface and the substrate,and thus the mechanical stability of the superhydrophobic surface was enhanced.(3)The anti-corrosion performance of copper-based superhydrophobic surfaces prepared by alkaline solution impregnation and sol-gel methods respectively was explored through electrochemical workstation.Compared with bare copper,the copper-based superhydrophobic surface prepared by immersion in alkaline solution for 10 minutes exhibited excellent corrosion resistance and stable super-hydrophobicity in high humidity and low temperature environments with the corrosion current density reduced by 2 orders of magnitude.While the copper with colored wear-resistant super-hydrophobic surface displayed superior anti-corrosion performance to that of super-hydrophobic surface prepared by alkaline solution immersion with corrosion current density reduced by 4 orders of magnitude.The results show that combination of epoxy resin layer and superhydrophobic coating make the obtained colored wear-resistant super-hydrophobic surface displayed strong anti-corrosion performance.(4)For the need of water collection process in the project,strip-shaped,square-shaped and superhydrophobic-hydrophilic circular-ring patterned wettable surfaces were prepared on titanium-based superhydrophobic surfaces by using ultraviolet lithography technology so as to expand the application range of superhydrophobic surfaces.The CA of the super-hydrophobic portion of the patterned wettable surface was larger than 150°and that of the super-hydrophilic portion was smaller than 5°.Compared with other surfaces,patterned wettable surfaces possesses stronger water-collecting ability,especially strip-shaped patterned wettable surfaces,the water-collecting efficiency of which could be as high as 3.2 g/cm~2·h.The improvement of the ability to trapping and transporting droplets make the patterned wettable surface exhibit higher water collection efficiency.