(54g) Dynamic Adsorption and Pinching Dynamics of Polymer-Surfactant Complexes

The interfacial and rheological properties of polymer-surfactant mixtures play a significant role in applications ranging from enhanced oil recovery, pharmaceutical, and biological fluids, cosmetics, food, soft adhesives, and coatings. The surface tension of a freshly created interface varies due to dynamic adsorption that is intimately linked with the rate of mass transfer of interfacially-active species from the liquid sub-phase to the interface. This adsorption-limited kinetics impacts the formation of drops and bubbles. In this contribution, we characterize dynamic adsorption of charged surfactants as well as surfactant-polymer complexes using a home-built maximum bubble pressure tensiometry (MBPT). Unlike the conventional methods that are limited in their temporal resolution, we show the measurement of dynamic surface tension at extremely short (1-50 ms) timescales. Additionally, we examine the pinching dynamics of charged a surfactant-neutral polymer system using dripping-onto-substrate (DoS) rheometry protocols. We characterize the influence of adsorption kinetics on pinching flows and determine the extensional rheological response of the mixtures. By combining the characterization of shear and extensional rheology behavior with dynamic adsorption studies, we elucidate the role played by polymer-surfactant complexes in dictating foamability, emulsion formation, and processability.