Synthesis of Fluoro-Functionalized Mesoporous Silica and Application to Fluorophilic Separations

Abstract

Fluorocarbon-functionalized mesoporous silica is synthesized by the co-condensation of tetraalkoxysilane and fluoro-functionalized alkoxysilane precursors using a cationic fluorocarbon surfactant, C6F13C2H2NC5H5Cl (HFOPC) and C8F17C2H2NC5H5Cl (HFDePC), or a traditional hydrocarbon surfactant (C16H33N(CH3)3Br, CTAB) as templates. Fluorocarbon functionalization decreases the silica pore order, pore size, and surface area. The chain length of the fluorocarbon functional precursor and the surfactant template affects the pore order, the materials textural properties, and the fluorocarbon incorporation. Matching a fluorocarbon surfactant with a fluorocarbon functional precursor does not improve functional group incorporation; the incorporation of the perfluoro-octyl functional group is greater in CTAB-templated silica than in HFOPC-templated silica. The application of these mesoporous silica powders to fluorous separations is demonstrated using hydrocarbon and fluorocarbon-tagged anthraquinones. Dye elution thr...