Hydrophobic silica aerogel (HSA) was synthesized by a facile sol–gel method and ambient pressure drying with methyltrimethoxysilane as precursor. The effect of precursor concentration on the sol–gel behavior, structure, and thermal conductivity of HSA was investigated. HSA with apparent density of 0.088 g/cm³ showed a thermal conductivity of 0.018 W/(m·K), a specific surface area of 502 m²/g and a pore volume of 1.66 cm³/g. The hydrophobic groups in HSA had a good thermal stability up to 450 °C. Polypropylene felt was used to synthesize hydrophobic silica aerogel composite (HSAC). The effect of sol loading on the structure and thermal conductivity of HSAC was investigated. HSAC with equivalent sol loading exhibited a low shrinkage of 2.5% and a low thermal conductivity of 0.020 W/(m·K). Finally, the preparation method of the HSA is facile and environmentally friendly, and the resulting composite is a promising candidate for thermal insulation under humid environments.

中文翻译：

---

功能性前驱体合成疏水性二氧化硅气凝胶及其复合材料

疏水性二氧化硅气凝胶（HSA）是通过一种简便的溶胶-凝胶法，并在常压下以甲基三甲氧基硅烷为前体进行干燥而合成的。研究了前驱体浓度对HSA溶胶-凝胶行为，结构和热导率的影响。表观密度为0.088 g / cm ^3的HSA的导热系数为0.018 W /（m·K），比表面积为502 m ² / g，孔容为1.66 cm ³/G。HSA中的疏水基团在高达450°C的温度下具有良好的热稳定性。聚丙烯毡用于合成疏水性二氧化硅气凝胶复合材料（HSAC）。研究了溶胶用量对HSAC结构和导热性能的影响。具有相等的溶胶负载量的HSAC表现出2.5％的低收缩率和0.020 W /（m·K）的低导热率。最后，HSA的制备方法既简便又环保，所得到的复合材料是在潮湿环境下进行隔热的有前途的候选材料。