Electrostatic charging of non-polar colloids by reverse micelles
Abstract
Colloids dispersed in a non-polar solvent become charged when reverse micelles are added. We study the charge of individual sterically-stabilized poly(methyl methacrylate) spheres dispersed in micellar solutions of the surfactants sodium bis(2-ethyl 1-hexyl) sulfosuccinate [AOT], zirconyl 2-ethyl hexanoate [Zr(Oct)], and a copolymer of poly(12-hydroxystearic acid)--poly(methyl methacrylate) [PHSA-PMMA]. Although the sign of the particle charge is positive for Zr(Oct), negative for AOT, and essentially neutral for PHSA-PMMA the different micellar systems display a number of common features. In particular, we demonstrate that, over a wide range of concentrations, the colloid charge is independent of the number of micelles added and scales linearly with the colloid size. A simple thermodynamic model, in which the particle charge is generated by the competitive adsorption of both positive and negative micelles, is in good agreement with the experimental data.
Keywords
Cite
@article{arxiv.0712.2768,
title = {Electrostatic charging of non-polar colloids by reverse micelles},
author = {G. Seth Roberts and Rodrigo Sanchez and Roger Kemp and Tiffany Wood and Paul Bartlett},
journal= {arXiv preprint arXiv:0712.2768},
year = {2007}
}