A study of the adsorption activities of silanol surface structures on a fused silica model substrate by combining 29Si CP MAS NMR and inverse gas chromatographic data

The possibilities of inverse gas‐solid chromatography (IGC) in obtaining chromatographic data on fumed silica were examined. Aerosil A‐200, a fused silica model substrate in 29Si nuclear magnetic resonance analysis, was trimethylsilylated to different degrees. IGC was used to very reproducibly determine the free specific energies of adsorption of several functionalized probe solutes. Hydrogen bonding solutes have a free specific energy of adsorption that is at least about 50% higher than that of non‐hydrogen bonding probe solutes. NMR was used in combination with elemental analysis to calculate surface concentrations of the different chemical surface structures. IGC data and surface concentrations were combined in order to determine the contribution of each type of surface structure to the total free specific adsorption energy. It could be concluded that residual silanols from the reaction of dihydroxydi‐siloxysiloxane (Q2 groups) with trimethylchlorosilane possess a higher adsorption activity than the silanols initially present.