title: Spontaneous charging and crystallization of water droplets in oil.
abstract: We study the spontaneous charging and the crystallization of spherical micron-sized water droplets dispersed in oil by numerically solving, within a Poisson-Boltzmann theory in the geometry of a spherical cell, for the density profiles of the cations and anions in the system. We take into account screening, ionic Born self-energy differences between oil and water, and partitioning of ions over the two media. We find that the surface charge density of the droplet as induced by the ion partitioning is significantly affected by the droplet curvature and by the finite density of the droplets. We also find that the salt concentration and the dielectric constant regime in which crystallization of the water droplets is predicted is enhanced substantially compared to results based on the planar oil-water interface, thereby improving quantitative agreement with recent experiments.
authors.affiliation: Institute for Theoretical Physics, Utrecht University, Leuvenlaan 4, 3584 CE Utrecht, The Netherlands. j.degraaf1@uu.nl
authors.forename: Joost
authors.initials: J
authors.lastname: de Graaf
authors.forename: Jos
authors.initials: J
authors.lastname: Zwanikken
authors.forename: Markus
authors.initials: M
authors.lastname: Bier
authors.forename: Arjen
authors.initials: A
authors.lastname: Baarsma
authors.forename: Yasha
authors.initials: Y
authors.lastname: Oloumi
authors.forename: Mischa
authors.initials: M
authors.lastname: Spelt
authors.forename: René
authors.initials: R
authors.lastname: van Roij