Tuning and controlling the shape of mesoporous silica particles with CTAB/sodium deoxycholate catanionic mixtures

Controlling the shape and size of mesoporous silica particles (MSPs) requires a deep understanding of the different parameters that play a major role during the synthesis of the materials. One of the key factors that can determine the morphology and porosity of the systems is the surfactant, used as a templating agent. We have very recently proven that binary mixtures of hexadecyltrimethylammonium bromide (CTAB) and bile salts are templating systems effective in controlling the morphology of MSPs in a facile and non-costly way. In this work we investigated the effect of different surfactant ratios in order to gain deeper insights on the influence of these catanionic mixtures on particle morphology. We employed mixtures of CTAB and sodium deoxycholate (NaDC) and upon variation of a sole parameter, the NaDC concentration, we achieved shape tuning. Hexagonal platelets, rods, oblate and toroidal particles were obtained and fully characterized. Moreover, investigation of the CTAB/NaDC assemblies showed that the morphology tuning is related to the evolution of the mixed micelles properties, occurring upon variation of the surfactant ratio.