| Special wettability includes superhydrophobic,superhydrophilic,superoleophobic and superoleophilic etc.,which can be applied to anti-corrosion,anti-icing,self-cleaning,oil/water separation,drug delivery and targeted release,developing controllable intelligent materials.Electrodeposition method has been widely utilized in fabricating films with special wettability because it has the advantages of simple operation,controllable quality and available for large area preparation.Preparing superhydrophobic films on metal surfaces is an effective way to improve the anti-corrosion property of metal substrates.In addition,superhydrophobic/ superoleophilic and superhydrophilic/ under water superoleophobic films can be used to oil-water separation.Therefore,the superhydrophobic/superoleophilic films not only can be applied to anti-corrosion,but also to oil/water separation,self-cleaning and so on.Moreover,research on films with switchable wettability will promote the development of intelligent materials.In this paper,a one-step electrodeposition method was utilized to fabricate corrosion and wear resistant superhydrophobic films on cathodic and anodic magnesium surfaces simultaneously.The properties of corrosion resistance,self-cleaning,chemical stability and wear resistance of the superhydrophobic films were tested,and the oil-water separation ability was initially explored.To further study the oil-water separation property,superhydrophobic films were prepared on copper meshes,of which the anti-corrosion capability and oil-water separation ability were studied.Finally,in order to promote the development of one-step electrodeposition and special wettability,films with switchable wettability were fabricated on stainless steel meshes.The transition process of wettability and oil-water separation characteristics were studied.(1)A one-step electrodeposition method was developed to simultaneously prepare superhydrophobic films on cathodic and anodic magnesium surfaces.The deposited voltage was changed to study the relationship between voltage and morphology and wettability of as-prepared films on cathodic and anodic magnesium surfaces.The cathodic and anodic films under the optimum condition were covered with micronodules that were consisted of nanosheets and composed of magnesium myristate,which had the maximum contact angles of 154.3° and 152.6°,and the rolling angles both are as low as 1°.Potentiodynamic polarization curves demonstrated that the corrosion current densities of the cathodic and anodic superhydrophobic films both decreased by about 2 orders of magnitude,and corrosion potential was 0.132 V and 0.108 V more positive compared with magnesium substrates.After 10 times of oil-absorbing and oil-degreasing tests,the oil absorption capacities of the cathodic and anodic superhydrophobic films maintained 7.62 g/g and 4.65 g/g,displaying a certain oil-water separation property.Using Al2O3,mosses and muddy as contaminants,water droplets on the cathodic and anodic superhydrophobic films were spherical and easy to roll,which carried the contaminants and regaining clean surfaces.In addition,the superhydrophobic surfaces both remained dry after 20 times of immersing into the muddy water,showing good self-cleaning effect.After immersed in 3.5 wt.% NaCl solution for 48 h,there was no change in the weight of the samples and no obvious declination of water contact angles,displaying good chemical stability.Moreover,water contact angles and slide angles on the superhydrophobic cathode and anode surfaces were greater than 150? with a slight declination even stored in the ambient environment above 28 weeks.The abrasion tests showed that under a pressure of 1.5 kPa,the cathodic and anodic superhydrophobic surfaces still maintained superhydrophobicity after abrasion on the sandpaper for 600 mm.However,when the abrasion length was increased to 700 mm,the superhydrophobic property was no longer existed,exhibiting certain wear resistance.(2)In order to promote the application of one-step electrodeposition method and superhydrophobicity in the oil-water separation area,the one-step electrodeposition method was applied to prepare superhydrophobic films on copper meshes.The effects of electrodeposition parameters on morphology and wettability of the as-prepared films were studied.Films under the optimum condition were covered with microstructures consisted of nanosheets and composed by copper myristate,which had the maximum water contact angles of 156.2° and the rolling angles are less than 1°.Polarization curves demonstrated that corrosion current densities of the superhydrophobic film was 4.77 × 10-9 A/cm2,decreased by more than 3 orders of magnitude,and the corrosion potential was 0.036 V more positive compared with the copper substrate.Moreover,the oil-water separation tests were conducted with separation appliance to study the oil-water separation capability of the superhydrophobic films.After the film reused for 5 times,the separation efficiency maintained above 95%,exhibiting excellent oil-water property and recycle capability.(3)On the basis of the above studies,the one-step electrodeposition method was used to fabricate films with switchable wettability on stainless steel meshes to extend the application of one-step electrodeposition method and materials with special wettability in intelligent material industry.This kind of method did not involve low surface energy materials and had advantages of simple and good repeatable.Through changing pH value,deposition temperature and voltage analyzed the relationship between morphology and wettability of the as-prepared films.There were a large number of particles on the film under the optimum condition and some of them aggregated into micro-pine hierarchical structures.The film achieved superhydrophobicity after certain heat treatment,and the water contact angle reached 155.5° and became brick red.After being placed at 450 ? for 3 h,the superhydrophobic film turned into superhydrophilic and became black.The film regained superhydrophobicity after hydrothermal treatment in glucose aqueous solution,which exhibited reversible transition between superhydrophobicity and superhydrophilicity.Investigating the chemical components of samples under different treatment was used to analyze the transition mechanism.The results demonstrated that the sample under certain heat treatment after electrodeposition was Cu2O.After high temperature treatment,the film was CuO and turned into Cu2O after hydrothermal treatment.The superhydrophobic films remained superhydrophobicity after being stored in room temperature for 40 weeks.Moreover,the oil-water separation capability was studied by separation appliance.The superhydrophobic films could be applied to separate heavy oil or organic solvent,such as dichloromethane and carbon tetrachloride etc.In addition,the superhydrophilic films could be used to separate light oil,such as diesel,gasoline,toluene,benzene and lubricants etc.All the films with special wettability exhibited excellent oil-water separation ability,which were above 95%?... |
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