Synthesis and Characterization of Hierarchically Ordered Porous Silica Materials

A series of hierarchically ordered porous silica composites were synthesized using anionic (SO₄^-2) polystyrene spheres and triblock copolymers Pluronic F127 (EO₁₀₇PO₇₀EO₁₀₇) and P123 (EO₂₀PO₇₀EO₂₀) as templates in the presence of cosurfactants (n-alcohols) in an acidic medium. The silica materials were characterized by XRD, SEM, TEM, Hg porosimetry, N₂ adsorption, solid-state NMR, and TG-DTA. At least three distinct pore sizes are observed in these materials. The composites consist of three-dimensional ordered macrospheres (200−800 nm) with interconnecting uniform-sized (70−130 nm) windows. The walls of these macrospheres consist of mesostructured pores (3−8 nm). Nitrogen adsorption indicates the presence of microporosity (<2 nm). Here, we report the detailed synthesis and characterization of such hierarchically ordered porous silica composites (Sen et al. U.K. Patent, GB 0201951.1; Angew. Chem., Int. Ed. 2003, 42, 4649) with macro−meso−microporous structure and a three-dimensional interconnectivity. These materials could be useful as potential supports for heterogeneous catalysis for bulkier molecules where diffusion of reactant molecules could be facilitated.