High surface area ethylene-bridged mesoporous and supermicroporous organosilica spheres

Abstract

Spheres of high surface area mesoporous or supermicroporous organosilica materials that contain ethylene groups within their framework have been prepared via surfactant (cetyltrimethylammonium bromide, CTAB) mediated assembly of distilled 1,2-bis(triethoxysilyl)ethylene (BTEE) in a modified Stöber process. The structurally well-ordered materials are made up of porous spheres (of size 0.5–1.0 μm) with narrow pore size distribution (average pore size of 2.2–2.6 nm) and surface area as high as 1884 m 2/g. The textural properties of the spheres are readily modified by changing the amount of ammonia in the synthesis gel of molar ratio BTEE:0.6CTAB: XNH 3:100CH 3CH 2OH:360H 2O, where X may be varied between 20 and 205. The presence of ethylene groups in the organosilica spheres was confirmed by 29Si and 13C MAS NMR and Raman spectroscopy. The ethylene groups are thermally stable up to a temperature of 300 °C and the organosilica spheres exhibit enhanced hydrothermal stability. The ethylene groups are accessible and reactive to further functionalisation; this was demonstrated by the bromination of the organosilica spheres.