Porous organosilicas: An acid-catalyzed approach

Porous organosilica materials have been synthesized by co-condensation of b is(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 mesosco pic composite was followed by surfactant extraction to form the porous orga nosilicas. These materials have been characterized by nitrogen gas sorption , metal ion adsorption, powder X-ray diffraction, elemental analysis, and h igh-resolution thermogravimetric analysis. The acid-catalyzed materials for med much faster and with twice the yield of similar organosilicas synthesiz ed under basic conditions. The final products of the acid synthesis also ex hibited higher concentrations of the AAPTS functional silane. Although thes e 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 structur al properties of the final products are examined.