Preparation and properties of fluorine-modified silica sol
[Introduction]Transparent and hydrophobic materials with special wettability have wide application prospects in self-cleaning,metal anticorrosion,microfluidic transport,anti-icing,and oil-water separation.[Method]A fluorine-modified silica sol was prepared by two-step method with tetraethyl orthosilicate(TEOS)as precursor and heptafluorosilane coupling agent(FAS)and epoxysilane coupling agent(KH560)as modifiers.Two hydrophobic materials were then prepared by coating the glass slice and polypropylene(PP)fabric with the fluorine-modified silica sol.The silica sol and hydrophobic materials were characterized by using contact angle goniometer,Fourier-transform infrared spectroscope,and scanning electron microscope.The effects of the dosage of modifiers,the proportion of ethanol during hydrolysis,and the dilution ratio on the hydrophobic properties of the materials were studied.[Result]The fluorine-modified silica sol prepared with 3%of total coupling agents at a FAS-to-KH560 mass ratio of 1:1 by hydrolysis in solution with a mass ratio of ethanol to water of 3:2 and 10-fold dilution could form a compact coating on glass and fabric,endowing their surfaces with a water contact angle of 112° and 153°,respectively.Moreover,the two hydrophobic materials possessed excellent self-cleaning performance.[Conclusion]The hydrophobic materials with excellent properties can be obtained via sol-gel method by co-hydrolysis of TEOS and FAS.
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