Research On Wetting Control Of Air In Water On Copper Mesh Surface

In past decades,although there has been a systematic study on surface wettability,research about wetting performance of gas on solid surface in water are still rare and only been reported in recent years.These reported underwater superaerophilic or superaerophobic surfaces have been demonstrated in many applications,such as superaerophilic electrodes,superaerophobic electrodes,directional transport of bubbles,and gas collection.However,these works are based on surfaces with single wetting performance,research about smart surfaces that can be regulated from underwater superaerophilicity to superaerophobicity are still limited.Herein,we proposed the research about gas wetting control on copper mesh film in water through the modification of responsive molecules and the addition of surfactant molecules.The main contents are as follows:Firstly,by using a simple electrodeposition process,the microstructure was constructed on the smooth copper mesh substrate.It is found that the best electrodeposition time is 20 s,and in this condition,uniform microstructure can be formed on the copper mesh substrate.Then the copper mesh was modified with a mixed solution of HS?CH₂?₉CH₃ and HS?CH₂?₁₀COOH to impart the surface with the pH-responsivity.One can observe that the surface has the best responsivity when the molar fraction of carboxyl groups in the modified mixed solution is 0.4.As to this surface,it is superaerophilic in an acidic water and superaerophobic in an alkaline water.At the same time,the as-prepared copper mesh membrane has a good stability,on which,reversible switching can be realized after multiple cycles without any loss of the responsivity.Based on the controllability of the surface,we further demonstrate the application in controlled infiltration of gas in water.Secondly,based on the same electrodeposition method,the microstructure was constructed on a smooth copper mesh,and then surface was changed to superhydrophobicity by modifying the fluorosilane.Then surfactant molecules including sodium bis?2-ethylhexyl?succinate sulfonate?AOT?,sodium dodecyl sulfonate?SDS?,dodecyl trimethyl ammonium bromide?DTAB?and dodecyldimethylamine beta?BS-12?were used to regulate the underwater gas wettings.It can be found that as the concentration of surfactant is increased,for all solutions containing the above used surfactant,the variation from the underwater superaerophilicity to superaerophobicity can be realized.However,for different surfactants,the critical concentration of the surfactant is different to realize the transition.For AOT,it is about 0.3mass%,which is apparently lower than other surfactants.This low critical concentration can be due to that different surfactants have different effects on the surface tension of aqueous solutions,and AOT can induce a lower surface tension compared with other surfactants.Based on the above studies,it can be concluded that the transition of gas wetting in water is ascribed to the synergistic effect of the surface microstructure on the copper mesh and the surface tension variation of the water environment.