Conditions for equilibrium solid-stabilized emulsions.
Particular types of solid-stabilized emulsions can be thermodynamically stable as evidenced by their spontaneous formation and monodisperse droplet size, which only depends on system parameters. Here, we investigate the generality of these equilibrium solid-stabilized emulsions with respect to the basic constituents: aqueous phase with ions, oil, and stabilizing particles. From systematic variations of these constituents, we identify general conditions for the spontaneous formation of monodisperse solid-stabilized emulsions droplets. We conclude that emulsion stability is achieved by a combination of solid particles as well as amphiphilic ions adsorbed at the droplet surface, and low interfacial tensions of the bare oil-water interface of order 10 mN/m or below. Furthermore, preferential wetting of the colloidal particles by the oil phase is necessary for thermodynamic stability. We demonstrate the sufficiency of these basic requirements by extending the observed thermodynamic stability to emulsions of different compositions. Our findings point to a new class of colloid-stabilized meso-emulsions with a potentially high impact on industrial emulsification processes due to the associated large energy savings.
Kraft
Daniela J
DJ
Van't Hoff Laboratory for Physical and Colloid Chemistry, Debye Institute for NanoMaterials Science, Padualaan 8, 3584 CH Utrecht, The Netherlands. d.j.kraft@uu.nl
de Folter
Julius W J
JW
Luigjes
Bob
B
Castillo
Sonja I R
SI
Sacanna
Stefano
S
Philipse
Albert P
AP
Kegel
Willem K
WK