Optically transparent, single-crystal-like oriented mesoporous silica films and plates

Optically transparent mesoporous silica plates, which are crack-free up to centimeters in size and 0.5 mm in thickness, have been synthesized using a sol-gel process based on the self-organization between surfactant and silicate through the van der Waals-type, weak, multiple, nonbonded interaction in nonaqueous solvents. The synthesis was controlled so that mesoporous channels with uniform diameter were either hexagonally packed, parallel to the flat external surface, or randomly oriented. The ordered silica plate exhibited uniform birefringence throughout the entire plate like a single crystal. The mesoporous silica shows possibilities of the application for advanced materials, direct measurement of transport properties through channels, investigation of the order-disorder effects, and spectroscopic investigation of adsorbed species without using the diffuse reflectance.