Weather Resistance And Failure Mechanism Of Hydrophobic And Superhydrophobic Surfaces Modified By Molecules

Hydrophobic and superhydrophobic surfaces have broad application prospects in the fields of anti-wetting,self-cleaning,drag reduction,anti-ice,anti-fog and anti-corrosion due to their unique properties.At present,there are various methods for preparing hydrophobic and superhydrophobic surfaces,but very few surfaces can be stably and persistently used in practical environments.Furthermore,there are few studies on the weatherability of hydrophobic and superhydrophobic surfaces in real application environments,and the cause of their hydrophobic/superhydrophobic failure in real environments is unknown,making it impossible to improve their weatherability from the ground up.In order to solve this problem,this thesis investigates the weather resistance of hydrophobic and superhydrophobic surfaces under various conditions as well as the failure mechanisms of hydrophobic/superhydrophobic surfaces.The following are the main research contents of this thesis:(1)Weather resistance of hydrophobic and superhydrophobic surfaces modified by molecules.In this work,alkyl silane,fluorosilane,siloxane and mercaptan modified hydrophobic surfaces,candle soot superhydrophobic surfaces,Ultra-Ever Dry superhydrophobic surfaces,and mercaptan-modified superhydrophobic copper surfaces were prepared.Weather resistance research is primarily divided into two categories:outdoor experiments and laboratory accelerated aging experiments.The laboratory accelerated aging conditions include ultraviolet(UV)radiation,water environment(spray and soak),UV radiation and condensation cycle,UV radiation,rain and condensation cycle,and salt spray.The hydrophobic and superhydrophobic surfaces were tested for weather resistance under the conditions described above.The change in apparent contact angle was used to analyze the weather resistance of the hydrophobic surface,and the change in contact angle and roll-off angle was used to analyze the weather resistance of the superhydrophobic surface.The results show that the hydrophobic surface modified with fluorosilane(PFOTS,PFDTS)has the best weather resistance,followed by the hydrophobic surface modified with siloxane(PDMS,DCDMS)and alkyl silane(DTS),and the hydrophobic copper surface modified with thiol(DT)has the worst.Among the superhydrophobic surfaces of candle soot,the fluorosilane modified armorized superhydrophobic surface has the best weather resistance,because the structural stability of the armorized surface is better than that of the ordinary surface,and the stability of fluorosilane is better than that of siloxane and alkyl silane.Among the Ultra-Ever Dry superhydrophobic surfaces,the armorized surface has better environmental weather resistance than the ordinary surface.It is very easy for the superhydrophobic properties of mercaptan-modified superhydrophobic copper surfaces to fail.(2)Failure mechanism of molecular modification of hydrophobic and superhydrophobic surfaces.The failure mechanism of hydrophobic surfaces was studied using XPS analysis of surface modified molecules,while the failure mechanism of superhydrophobic surfaces was studied using SEM analysis of surface rough structure changes and XPS analysis of modified molecules.The failure of the hydrophobic surface may be caused by the covalent bond break between the modified molecule and the substrate,resulting in the removal of the modified molecule from the surface and the loss of its hydrophobic property.The weather resistance of superhydrophobic surfaces in the actual environment is determined by the stability of the rough structure and modified molecules.Superhydrophobic failure will occur if the rough structure or modified molecules fail.