Evolution of block copolymer template structure during the synthesis of ordered mesoporous silica

Abstract

The popular belief is that synthesis of mesoporous silica of SBA-15 type proceeds through the phase transformation of block copolymer template which consists in the association of initial spherical micelles into rods or/and cylinders that self-assemble then into hexagonal mesophase. Herein, we showed based on transmission electron microscope observations and mesoporosity characterization by nitrogen adsorption that admixing of silica precursor into a solution of block copolymer triggers a set of transformations first of which is self-organization of initial spherical micelles into the hexagonal mesophase in which their subsequent unidirectional merging results in parallel alignment of cylindrical aggregates that determines the final regular mesoporous structure of silica.