Wang Xiaoqing, Li Chengyuan, Shi Zhenyu, Zhi Mingjia, Hong Zhanglian
State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University Hangzhou 310027 China
RSC Adv. 2018 Feb 22;8(15):8011-8020. doi: 10.1039/c7ra13041d. eCollection 2018 Feb 19.
In our previous work, a citric acid assisted sol-gel method was developed for preparing monolithic metal oxide aerogels. Such method adopted citric acid as the gelator, which replaced the well-studied proton scavenger propylene oxide. In this work, we have further extended this "organic acid assisted" sol-gel method and investigated the gelation mechanism. Four different organic acids (butanedioic acid, l-malic acid, l-aspartic acid and mercaptosuccinic acid) with an identical main chain but different side groups were used as the gelators for preparing monolithic zirconia aerogels. It was found that complex interactions including covalent bond and coordination bond interactions between organic acids and zirconium ions were vital to give a rigid gel network. After supercritical drying, crystalline zirconia aerogels can be obtained with high surface areas over 330 m g and large pore volumes over 3.574 cm g.
在我们之前的工作中，开发了一种柠檬酸辅助的溶胶-凝胶法来制备整体式金属氧化物气凝胶。该方法采用柠檬酸作为胶凝剂，取代了经过充分研究的质子清除剂环氧丙烷。在这项工作中，我们进一步扩展了这种“有机酸辅助”溶胶-凝胶法，并研究了凝胶化机理。使用四种具有相同主链但不同侧基的不同有机酸（丁二酸、L-苹果酸、L-天冬氨酸和巯基琥珀酸）作为制备整体式氧化锆气凝胶的胶凝剂。发现有机酸与锆离子之间包括共价键和配位键相互作用在内的复杂相互作用对于形成刚性凝胶网络至关重要。经过超临界干燥后，可以获得具有超过330 m²/g的高比表面积和超过3.574 cm³/g的大孔体积的结晶氧化锆气凝胶。
