Hydrophobic ambient pressure drying (APD) aerogels were prepared from hydrolysis of tetraethylorthosilicate (TEOS) in solutions with different concentrations of poly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide) (F127). APD was carried out after silylation of wet gels with 20% by volume of hexamethyldisilazane (HMDZ) in n-hexane. The samples were analyzed by small-angle X-ray scattering (SAXS) and nitrogen adsorption. The APD aerogels obtained in this process were submitted to heat treatment at 300, 500, 700 and 900 °C to study the pores stability. The samples were characterized by nitrogen adsorption. Wet gels are formed by mass-fractal domains, with fractal dimension close to 2.1 and characteristic size (ξ) spanning from about 9 nm (for the gel prepared without the addition of F127) up to values that exceed the maximum limit of the SAXS experimental setup, with increasing the concentration of F127. Nitrogen adsorption data showed that the pore volume (V_p) and the mean pore size (l_p) of the aerogels increased with increasing the concentration of F127. The drying process diminished the characteristic size ξand increased the dimension D of the mass-fractal domains and the size (r₀) of the primary particles of the aerogels with respect to the wet gels. The characteristic size ξ of the mass-fractal of the aerogels was found significantly larger with increasing the concentrations of F127. Thermally treated aerogels exhibited a similar general behavior with temperature independent of the concentration of F127. The porosity was found fairly stable up to about 500 °C. The porosity started to be eliminated at 700 °C and it was found practically collapsed at 900 °C. The silylation layer on the silica surface of the present APD aerogels was promptly eliminated at about 350 °C yielding complete loss of hydrophobicity.

疏水性常压干燥（APD）气凝胶是由原硅酸四乙酯（TEOS）在具有不同浓度的聚环氧乙烷-聚环氧丙烷-聚环氧乙烷（F127）的溶液中水解制得的。在湿凝胶与20％体积的六甲基二硅氮烷（HMDZ）在正己烷中甲硅烷基化后，进行APD。通过小角度X射线散射（SAXS）和氮吸附来分析样品。在此过程中获得的APD气凝胶在300、500、700和900°C下进行热处理，以研究孔的稳定性。样品通过氮吸附进行表征。湿凝胶由质量分形域形成，其分形维数接近2.1，特征尺寸（ξ）范围从约9 nm（对于不添加F127制备的凝胶）到超过SAXS实验设置最大限值的值，同时增加了F127的浓度。氮吸附数据表明，气凝胶的孔体积（V _p）和平均孔径（l _p）随着F127浓度的增加而增加。干燥过程减小了特征尺寸ξ，并增加了质量分数域的尺寸D和相对于湿凝胶的气凝胶初级颗粒的尺寸（r ₀）。特征尺寸ξ发现随着F127浓度的增加，气凝胶的质量分数显着增加。热处理的气凝胶在与温度无关的F127浓度下表现出相似的一般行为。发现在约500℃下孔隙率相当稳定。孔隙率在700°C时开始消除，发现在900°C时几乎消失了。在约350℃下迅速消除了本发明APD气凝胶的二氧化硅表面上的甲硅烷基化层，从而完全丧失了疏水性。