DYNAMICS OF SURFACTANT ADSORPTION FROM SOLUTION CONSIDERING AGGREGATION WITHIN THE ADSORPTION LAYER

The theory of diffusion-controlled adsorption kinetics is developed fo r adsorption layers of surfactant molecules able to form two-dimension al aggregates. It is shown that the formation of such aggregates withi n the adsorption layer results in a deceleration of the surface tensio n decrease and in a reduction of the dynamic surface pressure when the system is far from the equilibrium state. If no aggregation of adsorb ed molecules is considered, then any decrease in adsorption rate is as cribed usually to the existence of an adsorption barrier. However, ass uming this two-dimensional aggregation, the diffusion model provides a much better description of phenomena that actually take place. A good correspondence is found between the experimental dynamic surface tens ions and theoretically calculated dependencies for the solutions of l- decanol for a mean aggregation number of 2.5 within the monolayer. The same aggregation number was estimated for decanol equilibrium monolay ers.