Micelle templating for the formulation of silica at the nanometer scale

The self-assembly of surfactant micelles and silica to form hybrid mesophases is a powerful tool to prepare silica formulations of unprecedented pore uniformity. The thermal stability of micelle-templated silicas (MTSs) is unexpectedly good, and they represent one of the stablest form of dispersed silica. An abacus for textural evaluation of the materials is given and a mechanism of degradation is proposed. Case histories exemplify the potential pitfalls of synthesis which can affect the quality of the final product. Metastabilities of the mesophase in the synthesis system, as well as instabilities during washing and calcination, can lead to broadening of the pore size distribution, spoiling the unique properties of MTSs. At present, the improvement of the stability of MTS towards hydrolysis probably represents the most important challenge to extend their field of application. (C) 2001 Elsevier Science B.V. All rights reserved.