摘要
讨论了正硅酸酯类化合物 醇 水体系凝胶玻璃的制备条件对其结构的影响.结果表明,应用溶胶 凝胶法制备SiO2凝胶玻璃主要包括凝胶的制备及其向玻璃转化两个过程.凝胶的制备是由Si(OR)4的水解和缩聚反应来实现,水和催化剂是影响水解和缩聚反应的主要因素.在Si(OR)4 C2H5OH H2O体系中,如果H2O与Si(OR)4摩尔比(R0)小于2,主要形成线性聚合物,随着加水量的增加将得到二维甚至三维网络结构的聚合物.酸催化时凝胶的密度比同组成的碱催化的要大.凝胶向玻璃的转化是在低于传统玻璃的熔化温度下进行.采用在反应溶液中加入N,N二甲基甲酰胺、乙二醇、草酸等控制干燥化学添加剂或使用超临界去除溶剂法,可以获得大尺寸的块状凝胶玻璃.
Solgel process of alkoxidederived SiO2 glass includes two steps: gel preparation and gel to glass conversion. The gel preparation is accomplished through polycondensation and hydrolysis of Si(OR)4. Water and catalysts are the main factors affecting the hydrolysis and polycondensation reactions. In a Si(OR)4C2H5OHH2Osystem, if H2O to Si(OR)4 mole ratio is less than 2, linear polymer chains will form as the main product. With increasing content of water, planar and even 3dimensional network will be obtained. Catalysts play an important role in the structure of the gels. The density of an acidcatalyzed gel is higher than that of the basecatalyzed gel of the same composition .The alkoxidederived gels have large specific surface area, high contents of OH and OR groups, and large free volume. The gel to glass conversion can be realized at a much lower temperature than in conventional melting procedure. In order to obtain a monolithic glass drying control chemical additives such as N, Ndimethyformamide, glycerol and some organic acid are introduced into the reaction solutions and hypercritical solvent evacuation procedure is utilized for drying the gels.
出处
《陕西师范大学学报（自然科学版）》
CAS
CSCD
北大核心
2003年第3期78-84,共7页
Journal of Shaanxi Normal University：Natural Science Edition
