(471i) Particle Stabilized Equilibrium Droplet Structures in Three Phase Liquid Systems

Particle stabilized emulsion droplets have been studied for more than a century, but gained renewed interest recently as templates and precursors for functionalized microcapsules that leverage modern methods of particle synthesis and surface modification.  According to the current understanding of Pickering emulsions, homogeneous particles can stabilize emulsions only kinetically, not thermodynamically. They can, however, change the thermodynamic equilibrium state of oil droplets at a water-air interface and even mediate complete spreading of an otherwise non-wetting liquid, as shown by Goedel et al.¹  Here we show that Goedel’s description of “particle-assisted wetting” can be extended to mixtures of 3 mutually immiscible liquids and predict the particle-mediated engulfment of one emulsion droplet in another. For liquids with appropriate interfacial tensions and particles with suitable wettability, particle adsorption at the liquid interfaces results in the thermodynamic stabilization of double emulsion droplets. We report theoretical predictions along with preliminary experimental evidence for the existence of thermodynamically stable Pickering double emulsion droplets.

1. Xu, H.; Yan, F.; Tierno, P.; Marczewski, D.; Goedel, W. A., Particle-assisted wetting. J. Phys.-Condes. Matter 2005, 17 (9), S465-S476.