| Abstract
| - The co-condensation of tetraethoxysilane (TEOS) and organotrialkoxysilane molecules byneutral alkylamine surfactant assembly (S0I0) is a convenient synthesis methodology forthe one-step preparation of organically functionalized mesostructured materials. Two distinctapproaches were considered for the formation of such hybrid inorganic−organic compounds,denoted as the template substitution and direct addition pathways. The template substitutionpathway, involving the replacement of both surfactant and TEOS by an equivalent amountof organosilane (up to 11% substitution), was convenient for the functionalization ofmesostructures with moieties whose size is comparable to that of the structure-directingamine surfactant. The direct addition method, involving the equimolar replacement of TEOSwith organosilane (up to 9% of total silicon) while keeping the surfactant amount constantin the reaction mixture, was successful for the incorporation of organic groups whose sizeswere smaller than that of the templating amine surfactant. Thus, the functionalization ofmesostructured silica was demonstrated using a wide range of organosilane species, includingoctyltriethoxysilane, mercaptopropyltrimethoxysilane, phenyltriethoxysilane, butyltrimethoxysilane, and propyltrimethoxysilane. Short-chain functional groups such as ethyltriethoxysilane, however, appeared to become occluded within the framework walls of HMS silica,resulting in a lowering of the framework order and the porosity of the hybrid materials. Asufficiently long carbon chain (at least three methylene units) in the functional group of theorganosilane allows an interaction with the hydrophobic core of the structure-directingmicelle, thereby permitting the successful incorporation of the organosilane into the porewalls of the mesostructure.
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