Gas chromatography study of silica modified with polyfluoroalkyl groups.

Silicas with attached polyfluoroalkyl groups were studied by gas chromatography (GC) at zero surface coverage. Organic molecules (n-alkanes, ethers, esters, ketones, etc.) were used as test compounds.

Peculiarities of adsorption of organic compounds and water on silicas with bonded polyfluoroalkyl groups.

The adsorption isotherms of benzene revealed the low adsorption potential of polyfluoroalkyl silicas compared with both initial silica and hexadecyl silica. Hydrophobicity of all modified silicas, measured by water adsorption, was rather close at p/p(s)=1 and was significantly different in the initial p/p(s) region: polyfluoroalkyl silicas did not nearly adsorb water but alkyl silica did it gradually. Thermodynamic parameters of adsorption of organic compounds of different nature were studied at a zero surface coverage by gas chromatography (GC).