Forces between a rigid probe particle and a liquid interface: Comparison between experiment and theory

Abstract

Forces between a silica colloidal particle probe and an immobilized decane droplet in a range of surfactant (sodium dodecyl sulfate, SDS) solution concentrations have been measured using the atomic force microscope. Independent measurements of the droplet ζ potential, colloidal probe surface potential, contact angle, interfacial tension, and probe radius are used as inputs into the interpretive theory developed by Chan et al. (J. Colloid Interface Sci. 2001, 236, 141) to provide a quantitative understanding of the measured forces operating at liquid-liquid interfaces. The theory is used to determine the true separation between the solid and the deformable liquid interface. It provides the li..