Preferential adsorption of solid monolayers of hydrocarbons over fluorocarbons at the solid/liquid interface

A novel combination of sensitive calorimetry, neutron diffraction and NMR have been used to investigate the preferential adsorption and phase behaviour of the solid monolayers absorbed onto graphite from binary n-alkane/n-perfluoroalkane mixtures. The results indicate that the alkane preferentially adsorbs for essentially all mixture compositions to the complete exclusion of the fluoroalkane. The fluoroalkane monolayer is completely displaced from the graphite surface on addition of the equivalent of just 1 ML of alkane to the mixture. The hydrocarbon is preferentially adsorbed both as solid monolayer and as a liquid.