Preparation And Corresponding Property Research Of Superwetting Patterned Nano-TiO₂ Surface

Recently,superhydrophobic surfaces have attracted much attention due to their wide applications in droplet manipulation,water collection,fluid transportation and so on.Among lots of superhydrophobic materials,TiO₂ becomes a research focus due to its excellent chemical stability,biocompatibility,light-induced responsivity in wettability.Based on the light response characteristics of TiO₂,allowiong itself to be used as the substrate for constructing the wetting patterns,which have deomonstrated lots of particular functions and also attracted much interesting.At present,superwetting patterned surfaces have been successfully realized on the superhydrophobic TiO₂ nanosubstrate by mask irradiation,laser treatment,ink coating,etc.,but almost all these works are focused in air condition.The studies of such patterned wetting surface in complex environments such as oil and water have never been reported.In this paper,superwetting patterned nano-TiO₂ surfaces with contrast hydrophilicity/hydrophobicity in oil and oleophilicity/oleophobicity in water were prepared,related wettability variation and application were also demonstrated.The main contents of the dissertation are as follows:Regular TiO₂ nanotube arrays?TNAs?were successfully prepared by anodization method.The effects of different oxidation time and calcination temperature on TNA morphology,crystal structure,and water wetting performance in oil were investigated.The results showed that under the experimental condition of oxidation time 180 min,and the calcination temperature of 350 ?,underoil superhydrophobic anatase-type TNA can be prepared.The effects of ultraviolet light irradiation and heat treatment on the surface wettability were investigated.Results showed that the as-prepared TNA is underoil superhydrophobic,after 60 minutes of UV irradiation,it became underoil superhydrophilic.After heat treatment at 150 ? for about 60 min,showing the recovery of superhydrophobicity in oil.On the surface,contrast wetting patterns of dots and lines with different geometrical dimensions were prepared by mask irradiation.It was found that the introduction of hydrophilic patterns can realize the smart control of surface wettability,especially the surface adhesion.The mechanism analysis indicated that the wetting controllability is ascribed to the combined effect of surface chemistry variation and the nanostructure of TNA.Finally,based on the smart regulation of surface adhesion,the application of such patterned surfaces in droplet storage and transfer were also explored.Based on the same method as above,regular TNA surface was prepared,and the effect of oxidation time,calcination temperature on the underwater oil wetting performance on the surface was explored.Results showed stable underwater superoleophobicity can be obtained on the TNA that is prepared with an oxidation time of 60 min and a calcination temperature of 350 ?.By coating oleophilic ink onto the surface,it can be seen that underwater oleophilicity can be realized,and after a further washing with acetone,the ink can be removed and the surface would returen to the intial underwater superoleophobicity.The mechanism analysis indicated that it is the variation of surface chemistry due to the introduction/removal of ink,and the combined action with the nanostructure,that endows the surface with smart switchable wetting performance.The point,and line-like contrast underwater oleophilic/oleophobic patterns of different geometrical dimensions were fabricated on the TNA surface by the method of overlay coating,and it is found that the introduction of oleophilic patterns can effectively lead to the variation of oil-adhesion on the surface.Finally,based on the special oil adhesion,some applications such as underwater oil droplet transport and mixing were also explored.