Microporous silica glass powder was fabricated by thermal decomposition of phenyl functions in organic-inorganic hybrid glass derived from tetraethyl orthosilicate (TEOS) and phenyltriethoxysilane (PTES). Micropores smaller than 1μm were mainly formed after the phenyl functions were completely removed by the thermal decomposition in air at 600°C. Mesopores with pore radius of 4 to 10nm were partly formed because of partial segregation of phenyl functions in the hybrid glass. Macroscopic segregation of the phenyl functions could be prevented because each phenyl functions were directly covalently bonded to silicon atoms constituting the siloxane skeleton structure of the microporous glass powder. The porosity increased with the added molar fraction of PTES to TEOS because of the increase in the phenyl functions. Nevertheless, the porosity was constant irrespective of the molar fraction of PTES when it was above 40% since a certain volume fraction of the siloxane structure was required for retaining the percolated structure of the siloxane bondings.
