ULTRASTABLE MESOSTRUCTURED SILICA VESICLES

A family of mesoporous molecular sieves (denoted MSU-G) with vesicleli ke hierarchical structures and unprecedented thermal (1000 degrees C) and hydrothermal stabilities (more than 150 hours at 100 degrees C) as sociated with high SiO4 cross-linking was prepared through a supramole cular assembly pathway that relies on hydrogen bonding between electri cally neutral gemini surfactants of the type CnH2n+1NH(CH2)(2)NH2 and silica precursors derived from tetraethylorthosilicate. The vesicle sh ells are constructed of one or more undulated silica sheets that are a bout 3 nanometers thick with mesopores (average diameters from 2.7 to 4.0 nanometers) running both parallel and orthogonal to the silica she ets, which makes the framework structure bicontinuous and highly acces sible. Catalytic metal ion centers [for example, Ti(IV) and Al(III)] h ave been incorporated into the framework with the retention of hierarc hical structure.