STABILITY AND ELECTROCHEMICAL-BEHAVIOR OF SELF-ASSEMBLED ADSORBATES WITH TERMINAL IONIC GROUPS

Self-assembled monolayers of surfactants with ionic functional groups are discussed from a thermodynamic point of view. The adsorption/desorption reaction, the stability of the monolayer, and the effect of the ionic adsorbate on the rate of electrochemical charge-transfer reactions are considered. On the basis of mainly evaluations of the electrostatic free energy of solvation it is shown that the ionic group has a strong destabilizing effect on the monolayer when the coated surface is immersed in solvents of high dielectric constants. The theoretical findings are substantiated by experiments with surfactants having the tetraalkylammonium group as a substituent in the omega-position to the binding function.