Periodic mesoporous silica gels

We have synthesized monolithic particulate gels of periodic mesoporous silica by adding tetramethoxysilane to a homogeneous alkaline micellar precursor solution. The gels exhibit 5 characteristic length scales over 4 orders of magnitude: fractal domains larger than the particle size (>500 nm), particles that are similar to 150 to 500 nm in diameter, interparticle pores that are on the order of the particle size, a feature in the gas adsorption measurements that indicates pores similar to 10-50 nm, and periodic hexagonal arrays of similar to 3 nm channels within each particle. The wet gel monoliths exhibit calculated densities as low as similar to 0.02 g/cc; the dried and calcined gels have hulk densities that range from similar to 0.3-0.5 g/cc. The materials possess large interparticle (similar to 1.0-2.3 cc/g) and intraparticle (similar to 0.6 cc/g) porosities.