Fabrication And Regulation Mechanism Of The Metallic Superhydrophobic Surface With Controllable Wettability

Inspired by nature,no matter the hydrophilic surfaces?hydrophobic surfaces or superhydrophobic surfaces have been widely investigated by researchers.However,the inspiration comes from the nature and we should go beyond nature.Nowadays,functional smart surfaces that can realize the transition between different wettabilities under external stimuli have been intensively researched because of their potential application in the fields of microfluidics,bio-detection,smart on-off systems and so on.Aluminum and its alloys have been widely applied in many fields such as aerospace,automobile,building,railway because of their excellent mechanical and processing properties.Thus,we selected aluminum as the base to prepare functional smart surfaces and it may further improve the application of aluminum in basic industry.In our experiment,we selected 3102 Al as the base and built micro-nano structure on aluminum alloys by anodic oxidation.We prepared p H-responsive superhydrophobic surface successively by one-step modificaiton.We summarized the surface structural characteristics under different parameters of anodic oxidation systemically and analyzed the influence of the modified solution concentration for the p H-responsiveness of the surface,further revealed the mechanism of realizing the p H-responsiveness.Based on the systematic analyzation of the modifying solution for the p H-responsiveness,we modified anodized aluminum alloys totally by HS(CH2)11CH3 and prepared low-adhesion superhydrophobic surface.We analyzed the wettability and corrosion resistance of the low-adhesion superhydrophobic surface and revealed the mechanism of the superhydrophobic for improving the corrosion resistance of aluminum alloys.We construct micro-nano structure on aluminum alloys by anodic oxidation,treated the anodized aluminum alloys by gold layer spraying and then modified the surfaces by thiols solution.By this way,we prepared the p H-responsive superhydrophobic surface.The surface can transit sharply from superhydrophobic state to superhydrophilic state,as the p H of the droplet increases from 7 to 12.DC voltage of 20 V,electrolytic reaction time of 120 min and the electrolyte containing40 ml absolute ethanol and 5ml 0.1mol/L Al(NO3)3 aqueous solution were considered as the optimum anodic oxidation parameters.The total concentration of the two thiols molecules in the ethanol solution was kept constant at 1m M · L-1,the ratio of HS(CH2)11CH3 and HS(CH2)10COOH was set as 3:7.The results of the SEM image,confocal laser scanning microscope image,X survey spectrum and FT-IR survey spectrum showed that the p H-responsive superhydrophibicity on aluminum alloy was determined by the microstructure and chemical composition.the anodized aluminum alloys sprayed with gold layer and then modified totally by HS(CH2)11CH3 was proved to be superhydrophobic with low adhesion.The contact angle was 162?,and slide angle was ~5°.Corrosion resistance test showed that the prepared superhydrophobic surface exhibited good corrosion resistance property compared with the untreated substrate and anodized sample in the 3.5 wt.% Na Cl solution.By combined with self-cleaning test and specular reflection phenomena,we demonstrated that the improvement of the corrosion resistance of the aluminum alloys was determined by the microstructure and water repellency of the superhydrophobic surface.