| Along with society’s progress and development, superhydrophobic materials have been concerned highly because of its unique performance, wide application field, and important research and application value. Many phenomena in nature, such as lotus leaf not be contaminated from the mud, insect walking on water, waterfowl feathers not be wetted by water, etc, show excellent superhydrophobic properties. These superhydrophobic properties mainly depend on the special structure and the wax of the surface. Observing these natural superhydrophobic instance, and studying the forming inner mechanism of the natural superhydrophobic surface, can provide many reality basis to construct artificial superhydrophobic surface, also provide more design ideas for exploiting and developing the multi-function of superhydrophobic surface. Material surface wettability depends on the surface chemistry and surface morphology of material. Therefore, controlling the surface chemistry and surface topography of material can control effectively the wettability of the surface of the material. When the material surface has low surface free energy, material can show the hydrophobic properties. At the same time, microstructure of the material surface is relatively rough, this make its surface easy to parcel air and form solid-gas composite surface, and also can reduce the surface free energy, produce good hydrophobic effect.According to the characteristics of lotus leaf surface micro-nanostructures, dispersion solution are prepared by biomimetic method using different raw materials. Silica/Polyurethane (SiO2/PU) super hydrophobic coating with rough surface micro-nanostructure similar to lotus leaf is build using the spraying process combining phase separation and self-assembly technology. Polyurethane material has superior performance. It can improve the mechanical strength of coating, making the coating has good adhesion with substrate, and good durability.The first method:firstly, functionalization modification of polypropylene glycol (PPG) is carried out with toluene diisocyanate (TDI) using dibulytin dilaurate (DBTL) as catalyst. Then the chain is extended adding hydroxyl silicone oil, obtaining wet type of organic silicone modified polyurethane. The wet type of organic silicone modified polyurethane and nano silicon dioxide is scattered into ethyl acetate by using ultrasonic, respectively. SiO2prepared using sol-gel method is dispersed in ethyl acetate, and then this dispersion is added into the polyurethane dispersion, and then stirred strongly to disperse evenly, obtaining SiO2/PU composite dispersion. Finally, SiO2/PU composite dispersion is sprayed onto slides or other materials by spray gun, and then coated materials are heated in the oven, forming the SiO2/PU coatings.The structure of the coating is confirmed by infrared spectrophotometer, the coating contact angle and rolling angle of water droplets is determined by contact angle tester and image analysis method, microscopic structure of the coating surface is observed by field emission scanning electron microscopy (SEM), and stripping experiments of different coatings is carried out by3M610type test tape. The change of the contact angle and rolling angle is observed, and the mechanical stability of the coating is analyzed. The superhydrophobic property and frost resistance of different coating material is also studied. The research results show that the SiO2/PU coating has rough micro-nano structure similar to the lotus leaf surface, and has excellent hydrophobic performance. The dosage of each component in the coating has great influence on the hydrophobic properties of the coating. When the quality ratio of SiO2to PU is from4:5to3:5, and organic silicon content is more than15%, the water contact angle of coating can reach to158°, and rolling angle3°. The superhydrophobic property of coating is obvious. Superhydrophobic SiO2/PU coating has stabile structure and good bonding strength. The contact angle of coating is still greater than150°, and rolling angle is less than10°after10times tape stripping test, and coating still have a superhydrophobic properties. For various materials, the coating shows good bonding strength, superhydrophobic property and frost resistance.The second method:firstly, fluffy silica powder is prepared using sol-gel method. SiO2ethyl acetate dispersion is added into the polyurethane dispersion, and then the perfluorinated alkyl ethyl acrylate (PEAC) copolymer solution is added. These content are stirred strongly to disperse evenly, obtaining SiO2/PU composite dispersion. Finally, SiO2/PU composite dispersion is sprayed onto slides or other materials by spray gun, and then coated materials are heated in the oven, forming the SiO2/PU coatings.The structure of the coating is confirmed by infrared spectrophotometer, the coating contact angle and rolling angle of water droplets is determined by contact angle tester and image analysis method, microscopic structure of the coating surface is observed by field emission scanning electron microscopy (SEM), and stripping experiments of different coatings is carried out by3M610type test tape. The change of the contact angle and rolling angle is observed, and the mechanical stability of the coating is analyzed. The superhydrophobic property of different coating material is also studied. The research results show that the SiO2/PU coating has rough micro-nano structure similar to the lotus leaf surface, and has excellent hydrophobic performance. The dosage of each component in the coating has great influence on the hydrophobic properties of the coating. When the SiO2content is9%, PU and PEAC content is15%and quality ratio is3:1, the water contact angle of coating can reach to161°, and rolling angle3°. The superhydrophobic property of coating is obvious. Superhydrophobic SiO2/PU coating has stabile structure and good bonding strength. The contact angle of coating is still greater than150°, and rolling angle is less than10°after10times tape stripping test, and coating still have a superhydrophobic properties. For various materials, the coating shows good bonding strength and superhydrophobic property. According to the characteristics of lotus leaf surface micro-nanostructures, titanium dioxide/Polyurethane (TiO2/PU) superhydrophobic coating with rough surface micro-nanostructure similar to lotus leaf is build using the spraying process combining phase separation and self-assembly technology.The structure of the coating is confirmed by infrared spectrophotometer, the coating contact angle and rolling angle of water droplets is determined by contact angle tester and image analysis method, microscopic structure of the coating surface is observed by field emission scanning electron microscopy (SEM), and stripping experiments of different coatings is carried out by3M610type test tape. The change of the contact angle and rolling angle is observed, and the mechanical stability of the coating is analyzed. The superhydrophobic property of different coating material is also studied. The research results show that the TiO2/PU coating has rough micro-nano structure similar to the lotus leaf surface, and has excellent hydrophobic performance. The dosage of each component in the coating has great influence on the hydrophobic properties of the coating. The water contact angle of coating can reach to156°, and rolling angle6°. The superhydrophobic property of coating is obvious. Superhydrophobic TiO2/PU coating has stabile structure and good bonding strength. The contact angle of coating is still greater than150°, and rolling angle is less than10°after10times tape stripping test, and coating still have a superhydrophobic properties. For various materials, the coating shows good bonding strength, superhydrophobic property. It is also found that because of the special physical and chemical properties of nanometer TiO2, TiO2/PU coating with strong hydrophobic properties has suddenly hydrophilic properties under UV irradiation, and this is also a new application prospect for the superhydrophobic materials containing nanometer titanium dioxide.Superhydrophobic coating this study prepared combines the advantages of polyurethane and nano-materials. It is easy to prepare, has good adhesion, massive preparation, structural stability, superhydrophobic properties and good durability. The requirements of method is not high to experiment conditions and equipment, the construction method is relatively simple, construction cost is relatively low, and is very suitable for promotion in industrial application. |
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