Emily Meyer1, Nicholas Ainger2, Neil Shaw2, and Raymond R. Dagastine1. (1) PFPC and the Department of Chemical and Biomolecular Engineering, University of Melbourne, Parkville, 3010, Australia, (2) Unilever R&D, Port Sunlight
The remarkable number of behaviors of polymer-surfactant complexes has lead to their use in a wide range of applications in personal care products, food formulations and pharmaceuticals. There has been considerable study of oppositely charged polymer-surfactant complexes in solution and, more recently, the behavior of such complexes and their components on surfaces have also been considered. However, little attention has been given to the dynamics process by which the interaction forces between adsorbed layers transition from repulsive forces to attractive forces with bulk concentration changes. In this work we use atomic force microscope (AFM) to investigate the properties of adsorbed polymer-surfactant complexes using anionic surfactants and cationic polyelectrolytes. Force vs separation data obtained with the AFM allow one to determine the adhesive properties of the system, conformational changes within the layer, and the dynamics of how these changes are occurring as a function of bulk surfactant and electrolyte concentrations. Force spectroscopy was also employed to probe polymer conformational changes and adhesion behavior.