Facile Synthesis of Meso/Macroporous Dual Materials with Ordered Mesopores Using Highly Concentrated Emulsions Based on a Cubic Liquid Crystal

Abstract

A new simple one-step method has been developed to obtain SiO(2) monolithic materials with a bimodal meso- and macroporous pore-size distribution. Sol-gel reactions were carried out in the continuous phase of highly concentrated emulsions with a cubic liquid crystal in this external phase, using a polyoxyethylene alkyl ether surfactant and containing a novel glycol-modified silane, tetra(2-hydroxyethyl) orthosilicate (abbreviated as THEOS). The hydrolysis and condensation reactions of this precursor have been carried out in basic pH, between pH 8.8 and 11.4. Interestingly, the ethylene glycol released during condensation reactions does not affect significantly the structure of the cubic liquid crystalline phase, which was stable during the sol-gel reactions. As a result, the cubic phase based emulsions could template the formation of meso/macroporous dual materials, which possess interconnected polydisperse macropores, between 1 and 5 μm, and cubic-ordered mesopores, with a narrow pore size distribution around 4 nm. Monoliths with a specific surface area higher than 550 m(2) g(-1) and bulk density of 0.16 g cm(-3) have been obtained.