A STUDY OF THE COMPETITIVE ADSORPTION OF A FLUOROSURFACTANT AT THE GELATIN AIR INTERFACE USING TIME-OF-FLIGHT SECONDARY-ION MASS-SPECTROMETRY

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) has been use d to follow qualitatively and quantitatively the displacement of gelat in by a fluorosurfactant from an interface over a wide concentration r ange from zero to beyond monolayer coverage of the fluorosurfactant. T he ToF-SIMS results are in good agreement with published wettability d ata and also show a good correlation with previously reported measurem ents using X-ray photoelectron spectroscopy (XPS). The ToF-SIMS result s indicate no change in the outermost surface chemistry above the poin t of monolayer coverage as defined according to the Gibbs adsorption m odel and that the surface displacement of gelatin by the fluorosurfact ant is effectively complete.