| The superhydrophobic self–cleaning coatings with"Lotus effect"has aroused much attention because of their unique surface properties and potential application. Hydrophobic functional gradient coatings with fluorine and silicone enriched in surface could be prepared by core–shell emulsion polymerization and self–stratification gradient technology, the contents of which have a gradient distribution from surface to inside. Superhydrophobic SiO2 films could be prepared by sol–gel method and self–assembly technology, by combination the construction of surface roughness and the modification of low surface energy materials.The acrylate copolymer emulsion containing fluorine and silicon with core–shell structure were synthesized by semi–continuous seed emulsion polymerization, using methyl methacrylate (MMA), butyl acrylate (BA) as main monomers, and dodecafluoroheptyl methacrylate (DFMA),γ–(methacryloxy)propyltrimethoxy silane (KH–570) as functional monomers, respectively. The influences of the type and content of emulsifier, the amount of fluorine and silicon monomers on the emulsion and properties of latex films were investigated, and the surface free energy of latex films was estimated using two classical different methods. The emulsion and their latex films were characterized by particle size distribution (PSD) analysis, transmission electron microscopy (TEM), Fourier transform infrared spectrum (FT–IR), nuclear magnetic resonance (1H NMR and 19F NMR) spectrometry, contact angle (CA), X–ray photoelectron spectroscopy (XPS), differential scanning calorimetry (DSC) and thermogravimetry (TG) analysis. The results indicate that both DFMA and KH–570 are effectively involved in the emulsion copolymerization, and the latex particles exist with obvious core–shell structure. The hydrophobicity and the oleophobicity of the latex films increase with the increase of the amount of DFMA and KH–570, while the water absorption decrease. The water absorption of latex film is low to 4.5%, and the contact angle with deioned water and diiodomethane are up to 110.6°and 76.8°, respectively, when the amount of DFMA and KH–570 are w=16% and w=5% of the total monomers, respectively. The surface free energy is as low as 15.4 mN?m-1, which is comparable to that of PTFE. With the addition of DFMA and KH–570, the decomposition temperature of latex films increase in the number of 77℃and 89℃, respectively. XPS analysis display that perfluoroalkyl and silicified groups have a gradient distribution in the structure of the latex films from the film–air interface to the film–glass interface. A series of SiO2 sol with different diameter were synthesized and modified by sol–gel method, and superhydrophobic coatings were prepared further by self–assembly function of fluorin–siloxane. The influences of the amount of silane coupling agent, the size of SiO2 on the morphology and wettability of the exterior coatings were discussed, and theoretical model on solid surface was analyzed. The results indicate that the prepared SiO2 particles have uniform size and distribution, and the silane coupling agent KH–570 is successfully grafted on the surface of SiO2 particles. Films with well–regulated surface could be obtained, when the amount of KH–570 is 30%~35% of SiO2, and the contact angle with deioned water is up to 152.9°. For the film surface of nanometer diameter particles, it forms a composite interface with microstructure on which the liquid droplets accord with Cassie model. It's an effective approach to obtain superhydrophobic surface to combine the construction of double–microcosmic rough surface with modification of low surface energy materials.
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