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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 .
Two precursors were prepared by cohydrolysis and two-step method using tetraethylorthosilicate [Si (OC2 H5) 4, TEOS] and methyltriethoxysilane [CH3Si (OC2 H5) 3, MTES] Different methyl-modified silica gels were used to measure the scattering intensity of the gel at the small-angle x-ray scattering (SAXS) station of Beijing Synchrotron Light Source (BSRF). The average particle size and the specific surface area between the two phases were calculated , Based on which the fractal characteristics of the gel were analyzed and found that there are fractal structures on two scales corresponding to two scales from primary particles of SiO2 to primary agglomerates and from primary agglomerates to clusters, Microscopic (TEM) observations confirmed that the gels obtained by the two methods had very different microstructures, and experiments show that using SAXS to study the fractal characteristics of methyl-modified gels is a powerful tool for obtaining gel microstructures.