Getting inside silica channels
Fluorinated surfactants have helped French chemists to get functional groups inside silica channels.
Functionalising the internal surface of mesoporous silica offers potential applications in catalysis, chromatography, photonics and nanotechnology. Hydrogenated surfactants are generally used to direct silica’s structure, however Catherine Rey? and co-workers from the Universit? de Montpellier II used a fluorinated surfactant and have made ordered silica that contains organo-fluorinated chains.
Fluorinated surfactants have a lot in common with their hydrocarbon counterparts, but it was their greater hydrophobicity and rigidity that interested Rey?. Fluorinated organotriethoxysilanes were grafted inside mesoporous silica’s channels in the presence of neutral or positively charged surfactants, to form wormhole microporous and hexagonal mesoporous hybrid materials, respectively.
Compared with hydrogenated surfactants, fluorinated versions allow more organo-fluorinated units to be grafted into the channels. If the materials show the enhanced properties anticipated, they will be useful for nanotechnology applications, like heat-resistant thermal coatings.
O Porcherie, Y Guari and C Reyé, New J. Chem., 2005 (DOI: 10.1039/b417756h)