Journal of Colloid and Interface Science, Vol.187, No.2, 304-312, 1997
Dynamic Surface-Tension and Adsorption-Kinetics from Micellar Solutions on Planar Surfaces
A qualitative theory of the dynamic surface tension and adsorption kinetics from micellar surfactant solutions on a planar surface is developed for the kinetic-diffusive-controlled adsorption process obeying any adsorption kinetics on a planar surface and any micellization-demicellization kinetics in the bulk. The time-dependent adsorption and dynamic surface tension is obtained in an analytical form for short and long times. It is shown that the adsorption process and dynamic surface tension over a wide range of surfactant (monomer) concentrations is governed by : (I) the adsorption kinetics of monomers and micelles for short times (0 less than or equal to t less than or equal to t(cr1)), (II) the adsorption kinetics of monomers and micelles on a planar surface and the micellization-demicellization kinetics in the bulk, and the diffusion of monomers and micelles for intermediate times (t(cr1) less than or equal to t less than or equal to t(cr2)), and (III) the diffusion of monomers and micelles for long times (t greater than or equal to t(cr2)). Formulas were derived to estimate the relaxation times t(cr1), t(cr2), and the parameters characterizing the adsorption process over a wide range of times. The existence of the (I), (II), and (III) regimes are justified by using the experimental data for the dynamic surface tension of a micellar Brij 58 solution.