Formation of Pseudo-lonic Lattice Structure in Ampholytic Surfactant Micelle as Analyzed by Counterion Binding Characteristics

Abstract

The interaction of sodium chloride with zwitterionic N-octylbetaine in aqueous solution was studied by proton spin-lattice relaxation time measurements above and below the critical micelle concentration of surfactant. The binding constant of sodium chloride to molecularly dispersed surfactant is far larger than to surfactant micelles. A model of two dimensional pseudo-ionic lattice structure (Fig. 3), which we have previously proposed for ampholytic phospholipid monolayer, is also applicable to the three dimensional molecular aggregates of zwitterionic surfactant.