Foamability of Aqueous Solutions of Charged Surfactants and of Surfactant-Polymer Mixtures*

Dynamic adsorption of a freshly created interface is intimately linked with the rate of mass transfer of surfactant from liquid sub-phase to the interface, and this adsorption-limited kinetics is said to impact the stability of the newly formed interface. Addition of polymer to a surfactant solution affects the dynamic adsorption and the rheological response due to the formation of association complexes. Dynamic surface tension refers to the time dependent variation in surface tension, which is related with the rate of mass transfer of a surfactant from liquid sub-phase to the interface. Dynamic surface tension measurements carried out with conventional methods like pendant drop analysis, Wilhelmy plate, etc. are limited in their temporal resolution. In this study, we apply the method of maximum bubble pressure tensiometry for the measurement of dynamic surface tension effects at extremely short (1-50 ms) timescales. We discuss the overall adsorption kinetics of charged surfactants and the influence of added polymer on dynamic surface tension. Finally, we examine how pinch-off dynamics and rheological properties are modified in the presence of added polymers by including a critical examination of shear and extensional rheological responses.