块状TiO2气凝胶的溶胶-凝胶过程及结构

 对块状TiO₂气凝胶的溶胶-凝胶过程及结构进行了实验研究，结果发现：增加催化剂的量，凝胶化时间缩短，湿凝胶的透明度降低，强度提高;增加前驱体的量，凝胶化时间缩短，湿凝胶的透明度变化不大，强度提高;增加水量，凝胶化时间先缩短后增加，湿凝胶透明度先减小后增加，强度先增加后减小。利用扫描电镜对超临界干燥法制备的不同催化剂量和密度的块状TiO₂气凝胶的结构进行了表征，并对结构与溶胶-凝胶过程之间的联系进行了分析。结果表明：增加催化剂量，由于缩聚反应进行的程度提高，气凝胶粒子粒径较小且总的孔径较大。减小前驱体量，气凝胶粒子粒径增大且结构逐渐疏松。

Structure and sol-gel process of monolithic TiO2 aerogels

The sol-gel process and structure of monolithic TiO2 aerogels were experimentally studied. It has been shown that, the increasing of the catalyst and precursor amounts can both lead to shorter gelation time and the hardness improvement of the wet gel, while they lead to a decrease and few change in the wet gel transparency, respectively. The gelation time, the transparency and hardness of the wet gel vary in the parabolic manner. The aerogels of different densities prepared with different catalyst amount were characterized by scanning electron microscopy. The reaction degree of polycondensation is found to increase with the increase of the catalyst and precursor amounts, the degree of cross linking of the aerogel colloid particles also increases, and no ≡C—O bond exists in the aerogels b