Mesoporous silica nanoparticles (MSNs) are experiencing rapid development in the biomedical field for imaging and for use in heterogeneous catalysis. Although the synthesis of MSNs with various morphologies and particle sizes has been reported, synthesis of a pore network with monodispersion control below 200 nm is still challenging. We achieved this goal using mild conditions. The reaction occurred at atmospheric pressure with a templating sol-gel technique using cetyltrimethylammonium (CTA(+)) as the templating surfactant and small organic amines (SOAs) as the mineralizing agent. Production of small pore sizes was performed for the first time, using pure and redispersible monodispersed porous nanophases with either stellate (ST) or raspberry-like (RB) channel morphologies. Tosylate (Tos(-)) counterions favored ST and bromide (Br(-)) RB morphologies at ultralow SOA concentrations. Both anions yielded a worm-like (WO) morphology at high SOA concentrations. A three-step formation mechanism based on self-assembly and ion competition at the electrical palisade of micelles is proposed. Facile recovery and redispersion using specific SOAs allowed a high yield production at the kilogram scale. This novel technique has practical applications in industry.

International audienceUltrastable MCM-48 silica with Ia3d cubic structure was synthesized by using only the surfactant cetyltrimethylammonium tosylate (CTATos) as template at extremely low surfactant concentration (CTATos/SiO2 = 0.068). Characterization by small-angle X-ray diffraction (XRD), nitrogen adsorption, and high-resolution transmission electron microscopy (HRTEM) clearly shows that the obtained MCM-48 silica has a highly ordered structure and large surface area (ca. 1281 m2/g) and pore volume (ca. 1.07 cm3/g). The regular cubic arrays were well retained even after this material was calcined at a high temperature of 900 °C for 3 h or heated at reflux in boiling water for 12 h. The Fourier transform infrared (FTIR) spectrum, thermogravimetric analysis (TG), and chemical analysis provide strong evidence that the formation of MCM-48 is attributed to the retention of tosylate (Tos–) counteranions of the surfactant in the interface between surfactant and silicate. The current synthetic strategy is suitable for routine and large-scale preparations of mesoporous silica with different topological structures