Influence of the block length of triblock copolymers on the formation of mesoporous silica

The effect of different block lengths of Pluronic surfactants, (EO)(x)-(PO)(y)-(EO)(x), in the formation of mesoporous silica has been investigated. The syntheses were performed in micellar solution of the surfactant under acidic conditions. The materials were characterized by SAXS, TEM and nitrogen adsorption measurements. The EO-block length of the polymers determines the mesostructure of the silica. For the hexagonal material (SBA-15) the wall thickness is largely dependent on the length of the EO-blocks, while the PO-block length has a great effect on the pore diameter. Furthermore, the PO-block length influences the templating ability, as longer PO-blocks result in more highly ordered domains and well defined particles. The synthesis temperature also influences these parameters. (C) 2003 Elsevier Science Inc. All rights reserved.