Surface modification is one of the important steps for synthesizing hydrophobic silica aerogels by ambient pressure drying in which silylating agent plays a vital role. Trimethylchlorosilane and many kinds of methoxysilanes like trimethylmethoxysilane, dimethyldimethoxysilane, and methyltrimethoxysilane have been used as the silylating agents. In this work, silylation effects were investigated with different molar ratios of silylating agent/n-hexane mixture. In addition, the mechanism of the silylation reaction is explained based on the molecular structures by considering the number of methoxy/methyl groups. The silylation extent was characterized by using optical imaging, bulk density and porosity analyses, Fourier-transform infrared spectroscopy, scanning electron microscopy, and Brunauer-Emmett-Teller, Barrett-Joyner-Halenda, and contact angle measurements. It has been found that the methoxysilane-based silylating agents can be used as a replacement without producing the harmful hydrochloric acid and retaining the similar tendency to trimethylchlorosilane in surface modification. This research approach seeks to an alternative silylating agent by investigating the impact on the surface modification based on the molecular structural parameters and reaction mechanisms.

表面改性是通过常压干燥合成疏水性二氧化硅气凝胶的重要步骤之一，其中甲硅烷基化剂起着至关重要的作用。三甲基氯硅烷和许多甲氧基硅烷如三甲基甲氧基硅烷，二甲基二甲氧基硅烷和甲基三甲氧基硅烷已被用作甲硅烷基化剂。在这项工作中，研究了甲硅烷基化剂/正己烷混合物的摩尔比不同时的甲硅烷基化效果。另外，通过考虑甲氧基/甲基的数目，基于分子结构来说明甲硅烷基化反应的机理。使用光学成像，堆积密度和孔隙率分析，傅立叶变换红外光谱，扫描电子显微镜以及Brunauer-Emmett-Teller，Barrett-Joyner-Halenda，和接触角测量。已经发现，基于甲氧基硅烷的甲硅烷基化剂可以用作替代物，而不会产生有害的盐酸并且在表面改性中保持与三甲基氯硅烷相似的趋势。该研究方法通过基于分子结构参数和反应机理研究对表面改性的影响，寻求一种替代的甲硅烷基化剂。