Self-adaptive Superhydrophobic Structure Design And Dynamic Anti-infiltration Mechanism

Due to the special structure and solid-liquid interface property,superhydrophobic surfaces performed unique functions such as surface self-cleaning,low adhesion,fluid drag reduction,etc.,which makes it exhibit great performance in the fields of navigation and engineering transportation.The application potential has received extensive attention from scientists and engineers in recent decades.However,in the process of superhydrophobic surfaces from design to application,there are still many problems need to be solved.Among them,how to maintain the stability of surface hydrophobic properties under harsh environments has become the key to whether superhydrophobic surfaces could be applied in practice.However,in the research of the design and optimization of superhydrophobic surfaces,once the structure is formed,the superhydrophobicity and stability also are determined.Therefore,in the beginning of the design,the hydrophobic property is sacrificed to ensure the stability under severe conditions unavoidably.As for such a question,we intend to design a superhydrophobic surface that automatically adjusts its structure guided by infiltration pressure,in order to achieve a dynamic balance of infiltration stability and solid-liquid adhesion.Meeting the low solid-liquid adhesion under normal conditions and improving the ability to resist wetting pressure under harsh conditions.Furthermore,finding a relatively universal preparation method for superhydrophobic surfaces and solving the key problem encountered in the actually application process.Main research contents of this thesis are as follows.Firstly,a facile preparation and design of superhydrophobic surfaces with re-entrant structures.This work derived from the surface feature of Salvinia leaf which demonstrated that the top of the surface microstructure could provide an energy barrier through pinning the liquid layer to maintain the superhydrophobic effect and prevent the air cushion collapsing when water weted the surface.We used surface tension and gravity to modify the micropillar arrays with a Salvinia leaf-like re-entrant structure,focusing on the designed re-entrant structures,we discussed the parameter range for large-area preparation.Following that,on the one hand,topography of the re-entrant structures were observed by scanning electron microscope,which proved that the preparation of re-entrant structures was flexible and controllable by this method.On the other hand,the confocal microscope was used to record of the liquid piercing process on the re-entrant structures in three-dimensional imaging,which explored the influence of the air cushion between the re-entrant structures to the superhydrophobicity and anti-infiltration stability.Secondly,self-adaptive superhydrophobic structure designs and dynamic anti-infiltration mechanism.Based on the developed method in previous step.In this work,through the combination of soft and hard materials,this composite structure had the ability to spontaneously respond to external forces to change its shape,thereby achieving a dynamic balance of stability and solid-liquid adhesion.In the specific experiment process,we used a surface tensiometer to measure the external pressure required for the transition of the liquid wetting state,and used a high-speed camera to observe the droplet motion process of the droplet impact to characterize the surface stability.Quantifying the degree of surface deformation by confocal microscopy.Finally,we also performed a series of simulations of adaptive superhydrophobic surfaces in practical applications.The proposal of self-adaptive superhydrophobic surface provides a new idea for the design of superhydrophobic surface and broadens the scope of its practical application.