The effect of dilute electrolytes on the formation of non-ionically templated [Si]-MSU-X mesoporous silica molecular sieves

The effect of adding dilute electrolytes to the synthesis of non-ionically templated [Si]-MSU-X mesostructures has been investigated. An assembly process, ((NM+)-M-0)((X-I0)), is described that takes into account both the non-ionic template/electrolyte and the silicate/electrolyte interactions. Monovalent cations (H+, Li+, Na+, K+, Cs+, NH4+) intervene in the template/silicate assembly process directing either the shape or the order of the macro-molecular templating structures to form worm-like and hexagonally ordered pore structures or bimodal mixtures of the two. Anions (F-, Cl-, Br-, I-, SO42-, NO3-, OAc-) interact with the tetraethylorthosilicate (TEOS) silica precursor to effect modifications in the rate of TEOS hydrolysis, the rate of particle nucleation and hence final particle size and the extent of silica cross-linking in the final templated material.