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arXiv · 1209.3618

Electrostatic Interactions between Janus Particles

Joost de Graaf·Niels Boon·Marjolein Dijkstra·René van Roij
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Abstract

In this paper we study the electrostatic properties of `Janus' spheres with unequal charge densities on both hemispheres. We introduce a method to compare primitive-model Monte Carlo simulations of the ionic double layer with predictions of (mean-field) nonlinear Poisson-Boltzmann theory. We also derive practical DLVO-like expressions that describe the Janus-particle pair interactions by mean-field theory. Using a large set of parameters, we are able to probe the range of validity of the Poisson-Boltzmann approximation, and thus of DLVO-like theories, for such particles. For homogeneously charged spheres this range corresponds well to the range that was predicted by field-theoretical studies of homogeneously charged flat surfaces. Moreover, we find similar ranges for colloids with a Janus-type charge distribution. The techniques and parameters we introduce show promise for future studies of an even wider class of charged-patterned particles.

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Joost de Graaf, Niels Boon, Marjolein Dijkstra, René van Roij. 2012-09-17. Electrostatic Interactions between Janus Particles. https://doi.org/10.1063/1.4751482

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