INTERFACIAL RHEOLOGY AND KINETICS OF ADSORPTION FROM SURFACTANT SOLUTIONS

A theoretical approach to the diffusion controlled kinetics of adsorption on the expanding interface of surfactant solutions is developed and compared with the experiment. This approach being an analogue of von Karman's approach to the hydrodynamic boundary layer is applicable to both submicellar and micellar surfactant solutions under large deviations from equilibrium. The partial differential equations of the convective diffusion are reduced to a set of ordinary differential equations of first order and algebraic equations. This simplifies the numerical computations and enhances the interpretation of the experimental data. Dynamic surface tension data for solutions of sodium dodecyl sulfate obtained by the maximum bubble pressure method are interpreted. Reasonable results for the diffusivity of monomers and the rate constant of micellar disintegration have been obtained. A local approach to interfacial rheology is briefly considered. The applicability of this approach to studies of visco-elastic dilational properties of adsorption layers from low molecular surfactants and proteins is demonstrated. 1