Preparation And Properties Of Several Micro/Nanostructured Superhydrophobic Materials

Superhydrophobic materials with unique surface characteristics have broad application prospects in human daily life,agriculture,industry and military.Many scholars have found that the wettability of solid surface is related to the surface roughness and surface chemistry,but the superhydrophobic state cannot be achieved by changing only the surface chemistry,so the surface roughness needs to be increased.It is found from the microscopic analysis of the surface of natural superhydrophobic materials that the micro/nano hierarchical structure of solid surface is considered as the key to obtain good superhydrophobic performance.How to construct a stable micro/nano hierarchical structure on solid surface artificially and quickly according to bionics principle and biological superhydrophobic surface,and how to obtain superhydrophobic materials with industrial application value has always been the focus of research.Therefore,we in this thesis mainly carried out the work from the following aspects:the influence of micro/nano hierarchical structure on the superhydrophobic property,the method of constructing the micro/nano hierarchical structure artificially,the way to improve the adhesion between the superhydrophobic coating and the substrate,and the rapid and environmentally friendly preparation of the superhydrophobic surface.The overall research work can be divided into the following four aspects:(1)The surface of natural diatomaceous earth with micro/nano structure was modified with perfluorosilane and then mixed with epoxy resin.The effect of the mass ratio of fluorinated diatomaceous earth to epoxy resin on the superhydrophobic property of the coating was studied.The coating has the characteristics of heat resistance and wear resistance.(2)Silica sol was introduced into hydroxyethyl methacrylate,sodium persulfate as initiator and triethanolamine as promoter,and gel was formed by free radical polymerization.After drying and physical crushing and sieving,SiO₂@polyacrylate particles with micro/nano hierarchical structure were obtained.The particles were modified by perfluorosilane and sprayed directly onto the substrate surface coated with epoxy resin.The coating can be placed in the room temperature for a long time and maintain the superhydrophobic property,in addition to wear resistance,dirt and water impact,and has a self-cleaning.(3)SiO₂@polyurea composite microspheres and cellulose nanocrystal@polyurea composite particles were prepared by using polyurea polymer as substrate.By introducing silica sol to prepare SiO₂@polyurea microspheres,it was found that when the remaining silica sol was added at an interval of 5 h,a large number of SiO₂ nanoparticles attached to the surface of polyurea microspheres could be obtained,which had obvious micro/nano hierarchical structure.The microspheres were sprayed onto the substrate surface containing fluorocarbon resin coating,and the superhydrophobic coating was successfully obtained after perfluorosilane modification.The coating can be placed for a long time its hydrophobic performance will not be reduced,and has good weather resistance,wear resistance,and self-cleaning.It was found in the experiment that cellulose nanocrystal was introduced to prepare cellulose nanocrystal@polyurea composite particles.When the addition amount of cellulose nanometer whisker was more than 2.0 g,irregular polyacrylate particles coated with cellulose nanocrystal could be prepared,with typical micro/nano hierarchical structure.The particles were modified with perfluorosilane and mixed with fluorocarbon resin.The superhydrophobic coating also has the characteristics of wear-resisting,anti-fouling,anti-corrosion and self-cleaning.(4)The rough surface with micro/nano hierarchical structure was formed by etching aluminum alloy with mixed acid solution,and the superhydrophobic surface was successfully obtained after perfluorosilane modification.It is found that the etching time has a great influence on the superhydrophobic performance of the superhydrophobic surface of aluminum alloy,and the surface hydrophobic effect is best when the etching time is 120 s.Aluminum alloy superhydrophobic surface can withstand high temperature heat treatment,and has a certain resistance to acetic acid and sodium chloride solution erosion capacity.In addition,PVDF superhydrophobic material was prepared on the surface of etched aluminum alloy by hot pressing with the characteristics of environmental protection and simple preparation process.According to the microscopic morphology,a large number of grass-blade protrusions formed on the surface of PVDF superhydrophobic material,and the tips of the protrusions reached the nanometer level,making it have superhydrophobic properties.In addition,PVDF superhydrophobic material also has resistance to acid,alkali and a variety of solvents erosion,durability,stripping resistance,contamination resistance and self-cleaning.