日本ゼオライト学会　刊行物 Publication of Japan Zeolite Association

While it is well known that the structure of the mesoporous materials templated by surfactant molecules depends on the molecular geometry of the surfactant species, little attention has been focused on the role of counter anions. We have revealed that the counteranions produce a dominating effect on the type of mesostructures prepared under acidic synthesis conditions using various acids. The mesoporous materials show the distinct morphology according to their space groups. It has been found that under the acidic conditions the mesophase is always transformed from the one with lower curvature into the one with high curvature through epitaxial growth. As the silica condensation causes the charge density of the silicate network to decrease, the organic surfactants pack to form a high surface curvature to maintain charge matching in the interface, so that the transformation to the higher curvature phase occurs. The mesophase formation is also greatly affected by a subtle change in the temperature, surfactant / silica / acid concentrations in water.