Micelle templating for the formulation of silica at the nanometer scale

The self-assembly of surfactant micelles and silica to form hybrid mesophas es is a powerful tool to prepare silica formulations of unprecedented pore uniformity. The thermal stability of micelle-templated silicas (MTSs) is un expectedly good, and they represent one of the stablest form of dispersed s ilica. An abacus for textural evaluation of the materials is given and a me chanism of degradation is proposed. Case histories exemplify the potential pitfalls of synthesis which can affect the quality of the final product. Me tastabilities of the mesophase in the synthesis system, as well as instabil ities during washing and calcination, can lead to broadening of the pore si ze distribution, spoiling the unique properties of MTSs. At present, the im provement of the stability of MTS towards hydrolysis probably represents th e most important challenge to extend their field of application. (C) 2001 E lsevier Science B.V. All rights reserved.