Functionalized mesoporous materials obtained via interfacial reactions in self-assembled silica-surfactant systems

A unique interfacial reactivity of self-assembled mesostructured silica-surfactant systems toward organosilanes was utilized to obtain ordered mesoporous materials such as MCM-41 with different surface functionality. The idea of this process is based on a direct replacement of electrostatic interactions between negatively charged silica species and surfactant cations by strong siloxane bonds. The current study shows that any suitable organosilane, having at least one reactive group (Cl-Si=, EtO-Si=, MeO-Si=) in the structure, is able to displace template from self-assembled silica-surfactant mesostructures and form a covalent bonding with the silica surface. The aforementioned displacement process allows for the synthesis of mesoporous materials with high degree of structural ordering, desired surface functionality and high coverage of bonded ligands. Also, a proper choice of silane and templating surfactant provides an opportunity to tune the pore size of the resulting materials. In addition, this process improves the stability of self-assembled mesoporous materials and preserves their structural ordering, which is not always achieved when the surfactant template is removed via calcination.