Spreading Of Soluble Surfactant Beyond The Critical Micelle Concentration

The droplet spreading of soluble surfactant beyond the critical micelle concentration appears across a wide range of contexts and it is of importance to investigate the dynamics and transport characteristics in theory and in practice. Under the thermal effect at the solid substrate or air-liquid interface, the theoretical model of soluble surfactant beyond the critical micelle concentration spreading on a pre-existing thin liquid layer is established and the nonlinear four evolution equations are derived for the film thickness and surfactant concentration at the interface and in the bulk and micelle concentration as monomers under the base state and disturbance state. The spreading of the droplet and the effects of the thickness ratio of the film to the drop height, the solubility parameter, the evaporation number, the capillary parameter, the sorption parameter and Peclet number on the evolution of the film thickness and surfactant concentration at the interface and in the bulk as monomers are investigated in details.