Spontaneous charging and crystallization of water droplets in oil

Joost de Graaf*, Jos Zwanikken, Markus Bier, Arjen Baarsma, Yasha Oloumi, Mischa Spelt, Rene van Roij

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


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.

Original languageEnglish
Article number194701
Number of pages9
JournalThe Journal of Chemical Physics
Issue number19
Publication statusPublished - 21 Nov 2008


  • crystallisation
  • drops
  • oils
  • permittivity
  • surface charging
  • water
  • IONS

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