In this work, the micro-structure and surface modification of sol-gel silica film were studied, for obtaining hydrophobic coatings with high transparency. Polyethylene glycol (PEG) was added into silica sol to adjust the particle size. Two kinds of surface modification (sol treatment and film treatment respectively) by hexamethyldisilazane (HMDS) were employed and compared. The particle size evolvement was measured by dynamic scattering particle size analyzer. The surface morphology, water contact angle, chemical compositions, and transmittance were characterized by atomic force microscope (AFM), contact angle instrument, transmittance, FTIR and UV-Vis-IR spectrophotometers. Results showed that addition of PEG increased the silica particle size and accordingly the film surface roughness, which gave rise to a significantly improved hydrophobicity. The surface modification was impacted by the particle size. Small particle size is good for sol treatment, while large particle size is good for film treatment. PEG-film after HMDS atmosphere treatment could present superhydrophobicity with water contact angle of 152°, and high transmittance was maintained at the same time.%通过引入聚乙二醇(PEG)改性传统二氧化硅(SiO2)溶胶,得到了粒径分布较宽且粒径可控的溶胶.比较了六甲基二硅氮烷(HMDS)溶胶内修饰和薄膜表面修饰以及溶胶粒径对SiO2薄膜疏水性能的影响.采用动态光散射粒度仪定量测试了二氧化硅溶胶老化过程中粒度的变化,用原子力显微镜、接触角测试仪、红外光谱仪、紫外-可见-近红外分光光度计分别对薄膜的表面形貌、表观静态接触角、薄膜成分及透光率等进行了测量.结果表明:PEG的添加可有效增大溶胶粒度从而增大薄膜的粗糙度,提高薄膜的疏水性.表面修饰效果受修饰方式和SiO2粒径影响,粒径较小时有利于溶胶内修饰,粒径较大时有利于对薄膜修饰.经过表面修饰剂(HMDS)的气氛处理得到了接触角为152°的超疏水薄膜,而且相比溶胶内修饰可以减小薄膜透光率的损失.
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