摘要: 为了制备疏水纳米SiO₂，提高在聚合物中的分散性，利用改进的 StÖber 法合成出纳米 SiO₂ ; 依据脱醇缩合原理，用有机溶剂置换醇水溶剂，以 γ－甲基丙烯酰氧基丙基三甲氧基硅烷( KH570) 作为改性剂对其进行原位改性; 通过红外光谱分析、扫描电镜、粒度分析及一系列疏水性能测试表征产物结构并评价疏水效果。结果表明，经表面改性纳米 SiO₂ 成功接枝上有机基团，颗粒形貌呈规则的球形，粒度约为 50 nm，团聚现象明显减弱。通过疏水效果测试，改性后的纳米 SiO₂ 能在有机溶剂中均匀分散，且在石蜡溶剂中能稳定存在 1 年以上; 因其吸水率减小至 28% ，亲油化度增大至 62% ，接触角由 23．1 °增大至 129．8 °，可见疏水效果大幅提高。通过研究改性条件得出: 最佳改性剂浓度为 60% ，最佳改性温度为 100 ℃，最佳改性时间为 25 h。

关键词: γ－甲基丙烯酰氧基丙基三甲氧基硅烷；改性；纳米 SiO₂ ；疏水

Abstract: In order to prepare hydrophobic nano-SiO₂ and improve the dispersibility in polymer materials，the nano-SiO₂was synthesized by the modified StÖber method．According to the principle of dealcohol condensation，organic solvents were used to replace alcohol water solvents，and γ－methacryloxypropyltrimethoxysilane( KH570) was used as modifier to modify in-situ．The infrared spectroscopy，scanning electron microscope，parlticle size analysis and a series of hydrophobic performance tests were used to characterize the product structure and evaluate the hydrophobic effect．The results show that the organic group is grafted onto the surface of nano-SiO₂ successfully through surface modification and the morphology of particle which size is about 50 nm with regularly spherical while agglomeration obviously reduces．The test of hydrophobic effect shows that the modified nano-SiO₂ can be uniformly dispersed in organic solvent and can be stable in paraffin solvent for more than 1 year．Owing to its water absorption decreases to 28% and lipophilicity increases to 62% as well as the contact angle increases from 23．1° to 129．8°，hydrophobic effect of the modified nano-SiO₂ is increased substantially．The investigation of the optimized modification show that the best modifier concentration is 60% ，the best modification temperature is 100 ℃ and the best modification time is 25 h．

Keywords: γ－methacryloxypropyltrimethoxysilane; modification; nano-SiO₂ ; hydrophobic