Assembly modulates dissociation: electrokinetic experiments reveal peculiarities of the charge formation at monolayer films

Self-assembled monomolecular films of alkanethiols chemisorbed on gold were used as a twodimensional model system to study the effects of spatial confinement of surface functional groups on their acid–base behaviour; reduction of the surface charge density by mixed assemblies revealed an increase of the acidity of carboxy groups; surfaces with low amounts of charged groups show the interplay of dissociation of functional groups and preferential adsorption of ions in terms of surface charge formation.