Control of helical silica nanostructures using a chiral surfactant

A chiral cationic surfactant that can form vesicle-like assemblies in pure water and fibrous aggregates in mixtures of water and alcohols was synthesized. Silicas having helical mesoporous nanostructures were prepared from TEOS using the self-assemblies of this surfactant as templates in mixtures of water and alcohols. By changing the concentration of catalyst and the ratio of alcohols to water, double helical mesoporous silica nanofibers, single-strand coiled mesoporous silica nanofibers, and twisted mesoporous silica ribbons have been prepared. Meanwhile, in some conditions, non-porous helical tubes, double twisted ribbons, and twisted ribbons were prepared. The helical pitches were controlled by changing the reaction conditions.