Toward a better control of internal structure and external morphology of mesoporous silicas synthesized using a nonionic surfactant

Mesoporous silicas with controlled morphologies have been synthesized using decaoxyethylene cetyl ether [C-16(EO)(10)] as a surfactant (10 wt % in aqueous solution). A large series of characterization results (SEM, TEM, XRD, and nitrogen adsorption-desorption analysis) have demonstrated how the surfactant/silica molar ratio as well as hydrothermal treatment conditions can drastically influence not only the regular organization of the compounds on the nanometer scale but also the morphogenesis of the particles at the micrometer level. High loadings of a silica precursor yield highly structured mesoporous compounds with a morphology of ropes, gyroids and toroids whereas an increase of the surfactant/silica molar ratio results in spherical materials with a disordered channel array. A phase transition from hexagonal to disordered structure and then again to a regular hexagonal array with increasing gel heating temperature from 40 to 80 degreesC has been evidenced.