Mesoporous Sieves with Unified Hybrid Inorganic/Organic Frameworks

Abstract

Mesoporous materials have been synthesized that are composed of hybrid frameworks in which inorganic and organic components have a fixed stoichiometry and are covalently bonded. The creation of UOFMN (unified organically functionalized mesoporous networks) materials incorporates concepts employed in the synthesis of MCM-41 mesoporous silicates, making use of a quaternary ammonium cationic surfactant and a double trialkoxysilyl precursor such as bis(triethoxysilyl)ethane (BTSE) or bis(triethoxysilyl)ethylene (BTSEY). The cetyltrimethylammonium (CTA+) surfactant is removed by extraction with acid, resulting in a high surface area porous organosilicate framework in which Si atoms are bridged by ethane (from BTSE) or ethylene (BTSEY) groups. The channels are wormlike and uniform in diameter. UOFMN materials are more hydrothermally stable than MCM-41 prepared under similar conditions and have thicker pore walls. Ethylene groups in products made with BTSEY can be brominated, the brominated product itself being reactive as a bromide source. The UOFMN products were characterized by XRD, N2 adsorption, solid-state 29Si and 13C NMR, and TEM.