Dynamic surface tensions and dynamic surface potentials of aqueous solutions of a cationic surface active electrolyte

Abstract

In this paper, dynamic surface tensions and dynamic surface potentials are compared for an ionic surfactant, myristyl trimethyl ammonium bromide (MTAB). This surfactant is cationic and therefore the potential due to the adsorbed dipoles adds to the double layer contribution. Moreover, for long chain ammonium salts, such as MTAB, the double layer potential can be effectively described by the Gouy-Chapman theory (the Stern potential may be neglected). The results indicate, in agreement with the non-ionics, that a transition exists from diffusion, through mixed, towards transfer controlled adsorption kinetics. Concerning the surface potential measurements again, a dipole relaxation is interfering with the adsorption process. In addition, for some concentrations a relaxation also appears in the double layer.