Porous organosilicas: An acid-catalyzed approach

Porous organosilica materials have been synthesized by co-condensation of bis(triethoxysilyl)ethane and N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (AAPTS) under acidic conditions. Cetyltrimethylammonium chloride was used as a porogen using the surfactant template method. Formation of the mesoscopic composite was followed by surfactant extraction to form the porous organosilicas. These materials have been characterized by nitrogen gas sorption, metal ion adsorption, powder X-ray diffraction, elemental analysis, and high-resolution thermogravimetric analysis. The acid-catalyzed materials formed much faster and with twice the yield of similar organosilicas synthesized under basic conditions. The final products of the acid synthesis also exhibited higher concentrations of the AAPTS functional silane. Although these acidic organosilicas show surface areas and total pore volumes similar to the corresponding base-catalyzed materials, they do not form ordered pore structures. The effects of AAPTS concentration on the chemical and structural properties of the final products are examined.