Home List of Titles Anomalous pH dependent stability behavior of surfactant-free nonpolar oil drops in aqueous electrolyte solutions
Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.3/190513
- Anomalous pH dependent stability behavior of surfactant-free nonpolar oil drops in aqueous electrolyte solutions
- Clasohm, Lucy Y.; Vakarelski, Ivan U.; Dagastine, Raymond R.; Chan, Derek Y. C.; Stevens, Geoffrey W.; Grieser, Franz
- Recent advances in atomic force microscopy (AFM) force measurement techniques have allowed the direct measurement and theoretical interpretation of the interaction between a liquid droplet and a solid surface or between two liquid droplets. In this study, we investigated the interaction across an aqueous thin film between fluorocarbon (perfluoropentane) droplets, hydrocarbon (tetradecane) droplets, and a droplet and a flat mica surface in the absence of stabilizers. It was found that even at a relatively elevated electrolyte concentration of 0.1 M NaNO3, depending on the solution pH, interactions between two identical droplets or a droplet and a mica surface could be repulsive. A simple theoretical analysis of the magnitude and range of these interactive forces suggests that the DLVO theory cannot explain the observed behavior. The measured force behavior is discussed in the context of ion adsorption, and the arising charging effects, at the bare oil-water interface.
- Publication type
- Journal article
- Langmuir, Vol. 23, no. 18 (Aug 2007), pp. 9335-9340
- Publication year
- FOR Code(s)
- 0306 Physical Chemistry (Incl. Structural); 0904 Chemical Engineering
- Atomic force microscopy; Drops; Electrolytes; Fluorocarbons; Liquid droplets; Mica; Oil drops; pH effects; Phase interfaces; Solid surfaces; Solutions
- American Chemical Society
- Publisher URL
- Copyright © 2007 American Chemical Society.
- Peer reviewed