title: Charging mechanism in colloidal particles leading to a linear relation between charge and size.
abstract: Colloidal particles that are dissolved in a liquid can become charged by preferential adsorption or dissociation of surface molecules. The assumption of a constant surface charge density leads to a particle charge that is proportional to the square of the radius. Recent experiments however have shown that in a number of cases the charge is linearly proportional to its size. We present a simple model for the charging of colloidal particles leading to a linear relation between charge and size in the framework of the mean-field Poisson-Boltzmann theory. The model is based on preferential adsorption or dissociation of surface molecules, in combination with a large concentration of chargeable surface sites. The model also predicts a surface potential that is independent of the particle size. Numerical simulations show that this model is in good agreement with analytical approximations.
authors.affiliation: Ghent University, Electronics and Information Systems, Sint-Pietersnieuwstraat 41, Ghent B-9000, Belgium. filip.strubbe@elis.ugent.be
authors.forename: Filip
authors.initials: F
authors.lastname: Strubbe
authors.forename: Filip
authors.initials: F
authors.lastname: Beunis
authors.forename: Matthias
authors.initials: M
authors.lastname: Marescaux
authors.forename: Kristiaan
authors.initials: K
authors.lastname: Neyts