Disordered mesoporous silicates formed by templation of a liquid crystal (L3)

Abstract

For a wide range of technological applications the need for optically transparent, monolithic, mesoporous silicates is readily apparent. Potential areas of utility include filtration, catalysis, and optoelectronics among many others. This laboratory has previously reported on the synthesis of such materials thatare formed through the addition of tetramethoxysilane to a liquid crystal solution of hexanol, cetylpyridinium chloride, and 0.2 M hydrochloric acid, and our investigation into the properties of these materials is a continuing process. We have achieved defect and fracture free material of suitable size (0.5 cm × 3 cm diameter disks) via supercritical drying of the silicate under ethanol or CO2. The dried materials are remarkably similar to ordinary glass in strength, texture, and clarity. They possess pore volumes of ca. 1.0 cm3/g, with BET surface areas >1000 m2/g. We can re-infiltrate thedried monolith with hydroxyethylacrylate, a photo-polymerizable monomer, to create an inorganic/organic nanocomposite. There is fracturing upon re-infiltration, but preliminary tests show that the polymerization proceeds despite the mechanical failure. These findings suggest many possible applications for these unique nanocomposites.

Theoretical Investigation of Dielectric Constant and Elastic Modulus of Three-Dimensional Isotropic Porous Silica Films with Cubic and Disordered Pore Arrangements

“…As for a 'disordered' porous structure, 12,[26][27][28][29][30][31] we have recently reported on a preparation technique and characterization results for silica-based low-k films. 13) We assume, for simplicity, that (1) the film is composed of polycrystalline domains, and that (2) each domain consists of nonperiodic cylindrical pores whose cylindrical axis directions are the same.…”

Ordered Meso‐ and Macroporous Binary and Mixed Metal Oxides

“…The L 3 phase consists of a surfactant bilayer forming a sponge-like structure with randomly distributed mesopores interconnected in all three dimensions. [175,176] The pore diameter in the L 3 phase increases with increasing solvent content, thus providing a procedure by which the pore diameter can be tuned to a specific size. Only the solvent, rather than the surfactant molecules, occupies the primary pore volume.…”