Fluorinated emulsions:: Templates for the direct preparation of macroporous-mesoporous silica with a highly ordered array of large mesopores

In this paper, we report the use of oil/water (O/W) fluorinated emulsions to design macroporous-mesoporous silica with a well-ordered array of mesopores. The emulsion is constituted of fluorocarbon droplets stabilized by the fluorinated surfactant molecules and dispersed in an O/W fluorinated microemulsion. A macroporous texture is clearly evidenced by SEM. The size of the macropores varies from 1.0 to 3.0 mu m. SAXS patterns of the materials and TEM experiments show that the mesoporous network adopts a hexagonal arrangement. A type IV isotherm is obtained by nitrogen adsorption-desorption analysis. The mesopore size distribution is narrow and centered on about 7.5 nm. We also proposed a mechanism to explain the formation of these hierarchically structured macroporous-mesoporous silicas. (c) 2006 Elsevier Inc. All rights reserved.