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采用无机分散溶胶凝胶法(DIS法),以TaCl_5乙醇-水混合溶液、聚丙烯酸(PAA)和环氧丙烷为反应物,一步反应制备了块体氧化钽基凝胶和相应的气凝胶。并采用环氧化物添加法(EA法,不添加PAA)合成了氧化钽基气凝胶作为参比样品。对2种方法制备气凝胶的实验现象、外观、密度、收缩率、微结构和化学成分进行表征和比较。结果表明,DIS法合成的气凝胶相比EA法合成的气凝胶具有更低的密度、更佳的成型性、更小的收缩率、更疏松的结构和更多的胶体成分。EA气凝胶的密度约为720 mg/cc,合成过程中收缩和开裂严重;而DIS气凝胶的密度约为390 mg/cc,成型性较好。EA法制备的氧化钽基溶胶的粒径在几纳米到几十纳米之间变化,而DIS法制备的溶胶粒径则集中分布在儿纳米。DIS气凝胶的主要成分为氧化钽基化合物和PAA的衍生物,而EA气凝胶的主要成分为氧化钽基化合物。此外,采用高分辨透射电子显微镜和傅立叶变换红外分光光度计研究了凝胶化机制。发现PAA在形成块体氧化钽基气凝胶的过程中表现出分散/络合的协同效应。
The bulk tantalum oxide-based gel and the corresponding aerogels were prepared by a one-step reaction using inorganic dispersion sol-gel method (DIS method), TaCl_5 ethanol-water mixed solution, polyacrylic acid (PAA) and propylene oxide . Tantalum oxide-based aerogels were synthesized by the epoxide addition method (EA method without PAA) as a reference sample. The experimental results, appearance, density, shrinkage, microstructure and chemical composition of two methods of preparing airgel were characterized and compared. The results show that the airgel synthesized by the DIS method has lower density, better formability, smaller shrinkage, more loose structure and more colloidal components than the airgel synthesized by the EA method. The density of EA airgel is about 720 mg / cc, with serious shrinkage and cracking during the synthesis. The density of airgel is about 390 mg / cc, and the formability is better. The particle size of tantalum oxide sol prepared by EA method varies from several nanometers to several tens of nanometers, while the particle size of sol prepared by DIS method is concentrated in nanometer nanometer. The main components of the DIS airgel are tantalum oxide-based compounds and derivatives of PAA, while the main component of the airgel is a tantalum oxide-based compound. In addition, the mechanism of gelation was investigated using high resolution transmission electron microscopy and Fourier transform infrared spectroscopy. PAA was found to exhibit a synergistic effect of dispersion / complexation during the formation of bulk tantalum-based airgel.