【摘要】 以正硅酸乙酯 [Si(OC2 H5) 4,TEOS]和甲基三乙氧基硅烷 [CH3Si(OC2 H5) 3,MTES]为前驱体 ,通过共水解法和两步法制备出两种不同的甲基改性氧化硅凝胶 ,在北京同步辐射光源 (BSRF)小角x射线散射 (SAXS)站测量了凝胶的散射强度 ,计算了凝胶的平均粒径、两相间比表面积等参数 ,在此基础上分析了凝胶的分形特征 ,发现存在两个尺度上的分形结构 ,分别对应于从SiO2 原生颗粒到一次团聚体和从一次团聚体到簇团两种尺度 .辅以透射电子显微镜 (TEM)观测 ,证实由两种方法获得的凝胶具有非常不同的微观结构 .实验证明 ,利用SAXS技术研究甲基改性凝胶的分形特征是获得凝胶微观结构的有力工具 .更多还原

【Abstract】 With tetraethoxysilane [Si(OC 2H 5) 4,TEOS] and methyltriethoxysilane [CH 3Si(OC 2H 5) 3,MTES] as precursors, two kinds of methyl modified silica gels were prepared by the two step method and co hydrolysis method. The gels were tested at the small angle x ray scattering(SAXS) Station of Beijing Synchrotron Radiation Facility(BSRF). We calculated the average particle diameter and the special surface area between the two phases. On the basis of these data the fractal characters of gels were analyzed, and two fractal structures were found in all the samples. The two fractal dimensions indicated two fractal structures on two scales, i.e., from primary SiO 2 particles to first aggregates and from first aggregates to clusters. Aided by transmission electronic microscope(TEM) we confirmed the two different microstructures of the gels prepared using the two different methods. It can be said that SAXS is a powerful technigue to study microstructures of gel systems by studying its fractal structure.更多还原