Study of hydration process on silica hydride surfaces by microcalorimetry and water adsorption.

A series of hydrosilated stationary phases were compared with respect to their hydrophilic-hydrophobic properties. The stationary phases were also compared to the bare silica gel used for this synthesis. The investigations were done using microcalorimetric measurements of methanol and acetonitrile heats of immersion. Because these stationary phases are used in both the reversed-phase and aqueous normal phase modes of liquid chromatography, the excess isotherm of water from acetonitrile solution was measured. From the materials tested the highest polarity was exhibited by the silica hydride and the bare silica. The Diamond Hydride is less polar. The highest hydrophobicity is exhibited by the hydrosilated stationary phase which contains bonded octadecyl ligands.