Like‐Charge Attraction: A Combined Electrostatic–Hydrodynamic Approach

Abstract

This article discusses the like‐charge attraction of colloidal spheres close to a charged plate and compares results produced by an electrostatic and a hydrodynamic model with experimental data. Hydrodynamic coupling is shown to be the dominating effect, while the electrostatic influence may often be neglected. Some observations, however, can be explained only by means of a combined electrostatic–hydrodynamic model, which is derived in this work. The combined model is able to predict not only the attractive force between particles of similar charge close to a charged plate but also the change to a purely repulsive force once the sphere‐plate distance is further reduced. This prediction matches qualitatively results of experiments reported in the literature.

Keywords:

• Like‐charge attraction
• Colloidal forces
• Electrostatic–hydrodynamic model

Acknowledgments

Partial support for this research was provided by the National Science Foundation through a Career Award (BES‐9702356 to S. Y.) and by the Division of Chemical Sciences, Office of Basic Energy Sciences, US Department of Energy, under contract DE‐AC05‐00OR22725 with UT‐Battelle, LLC. The authors are also thankful to Dr. Marsha K. Savage for editing the manuscript.

Additional information

Notes on contributors

Thorben Benesch

Thorben Benesch is BASF AG Corporate Engineering, Ludwigshafen, Germany; E‐mail: thorben.benesch@basf‐ag.de.