The direct synthesis of well-ordered spherical CMI-1 mesoporous materials, analogous to MCM-41 has been driven by variation of the weight percentage of decaoxyethylene cetyl ether [C16(EO)10] in the aqueous solution. These compounds exhibit very high specific surface areas (> 800 m'/g) and a hexagonal arrangement of channels. Our results obtained by X-ray diffraction, TEM, SEM and nitrogen adsorption-desorption analysis lead us to propose two different synthesis pathways for surfactant weight concentrations in aqueous solution higher and lower than 30% respectively. For samples obtained with an elevated weight percentage of C16(EO)10, it has been found that in addition to the possible perturbation induced by methanol released in low amount during the hydrolysis of TMOS, other factors such as the interactions of the silica source with hydrophilic chain heads of surfactant molecules should also disturb the preformed hexagonal micelle array and disordered wormhole mesostructured materials (DWM), analogous to MSU, are obtained. For the synthesis with a C16(EO)10 concentration less than 30 wt.%, a cooperative mechanism, which involves the polymerization of silica source and the interface interactions between the hydroxyl groups of silica source produced from the hydrolysis of TMOS and hydrophilic chain heads of surfactant molecules which are present in the single rod micelle form, has been evidenced, leading to well ordered materials with hexagonal arrangement of their channels. We also show that the morphology, textural and structural properties of materials are strongly affected by the stirring time.
|Number of pages||12|
|Journal||Chemistry of Materials|
|Publication status||Unpublished - 2001|