Synthesis of highly ordered, three-dimensional, macroporous structures of amorphous or crystalline inorganic oxides, phosphates, and hybrid composites

The synthesis of highly ordered macroporous materials has been accomplished in a straightforward, single-step reaction. Inorganic frameworks composed of oxides of Si, Ti, Zr, Al, W, Fe, Sb, and a Zr/Y mixture were formed from metal alkoxide precursors templated around polystyrene (latex) spheres. Mo nodisperse latex spheres were ordered into close-packed arrays by centrifug ation. The interstices between latex spheres were permeated by the alkoxide , which hydrolyzed and condensed. An inorganic framework was formed upon dr ying. Removal of the latex spheres was accomplished by either calcination a t temperatures between 450 and 1000 degrees C or extraction with a tetrahyd rofuran/acetone mixture. The resulting products consisted of periodic, inte rconnected networks of monodisperse submicron pores extending over hundreds of micrometers. Depending on the technique of template removal, various ph ases of the inorganic oxide could be formed. For example, in the case of ti tania, an amorphous phase was formed upon extraction of TiO2 and anatase by calcination at 450 degrees C. The synthesis has also been expanded to othe r compositions including aluminophosphates and hybrid organosilicates, as w ell as silicates with bimodal distributions of meso- and macropores. The ma terials presented in this paper show the diversity of macroporous materials achievable with this technique. These structures could potentially find ap plications as chromatographic support materials, solid catalysts, battery m aterials, thermal insulators, or photonic crystals.