Two kinds of methyl modified silica xerogels were prepared by mixing SiO 2 colloidal suspension deriving from basic catalyzed hydrolysis of TEOS (tetraethoxysilane) and siloxane polymer solution prepared from acid catalyzed hydrolysis of MTES (methyltriethoxysilane) or DDS (dimethyldiethoxysilane). The xerogels were tested at the small angle x ray scattering (SAXS) station of Beijing Synchrotron Radiation Facility. The distribution of pore size, the average size of pores D SAXS , and the thickn...