A broadband antireflective SiO2 coating with high transmittance and good hydrophobicity in the visible range was successfully prepared by template-free sol-gel method. The refractive indices of the bottom layer and top layer of the coating are 1.34 and 1.15,respectively.The bottom layer was prepared by mixing SiO2 sols catalyzed by acid and base,and the sol of the top layer was prepared by using hexamethyldisilazane ( HMDS) as modifier,which is composed of trimethylsilanized SiO2 nanoparticles. According to the design requirements of the optimized film system,suitable technological parameters were selected to prepare the double-layer coating.The test results show that the average transmittance of the SiO2 double-layer coating in the visible light region is 98.64％,and the static water contact angle can reach 134°.
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