The formation of hexagonal and lamellar surfactant−silicate mesophases at room temperature has been investigated by in situ synchrotron small angle X-ray scattering. Emphasis was given to the influence of butanol and hexanol on the surfactant−silicate phase behavior. The experimental setup included a continuous flow reactor allowing a resolution in time as high as 0.3 s. Depending on the reaction composition, one, two, or three coexisting phases were observed. The results are discussed in terms of time-dependent changes in the concentration of cosurfactant not incorporated into the composite aggregates. Although many of the observed effects are paralleled by well-known properties of aqueous surfactant solutions, important dissimilarities exist. Furthermore, the relative intensity of the high-order reflections are suggested to correspond to the degree of interaggregate condensation in the composite mesophas
Mesoscopically ordered silicate-surfactant composite materials of the M41S type synthesized in the presence of a swollen agent have been characterized by in situ and ex situ X-ray diffraction analysis. The key feature of the room-temperature synthesis is the use of a mixture of cationic and anionic surfactants as structure-directing agents. The lower interfacial charge density of the mixed surfactant aggregates stabilizes structures of lower interfacial curvature and therefore facilitates a more controlled solubilization of organic swelling agents. An increased solubilization capacity of the catanionic surfactant-silicate mesophase was observed close to an anionic/cationic surfactant ratio corresponding to a transition to the lamellar phase in the absence of toluene. In the presence of toluene, the catanionic template stabilizes microemulsion droplets that serve as building blocks for the final material. However, a fair amount of organic compound is solubilized in the silica-catanionic surfactant composite after the mesophase is formed. Although the present communication concerns mesoporous silica, the concept is a general one and may allow the synthesis of non-siliceous large-pore materials.
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