Hindered diffusion of an oil drop under confinement and surface forces

Abstract

Theoretical modeling of coalescence and drop-drop collision stability relies on an accurate physical understanding of surface forces, hydrodynamic drainage behavior, deformation, and internal drop flow. Brownian diffusion of alkane drops emulsified in aqueous solutions above a silica plate is measured using the total internal reflection microscope (TIRM). The behavior of drops over a range of separations is consistent with an immobile oil-water interface in both clean and anionic surfactant systems, counter to the hydro-dynamic boundary conditions commonly assumed for fluid-fluid interfaces.