Scenario for equilibrium solid-stabilized emulsions.
We show theoretically that under certain conditions colloidal particles can give rise to spontaneous emulsification of oil/water systems. The capillary penalty to create a large interface is compensated by entropic contributions connected to ionic dissociation on the colloid surfaces. The colloids themselves are absorbed on the oil/water interface. The conditions for spontaneous emulsification are: (1) oil-water interfacial tension is low (a few mN/m or lower); (2) interfacial tension between colloids and oil is smaller than between colloids and water (in the absence of charge effects); (3) density of chargeable groups on the colloids is large (order 1 nm-2); (4) Debye length is comparable to colloid size.
Kegel
Willem K
WK
Van't Hoff Laboratory for Physical and Colloid Chemistry, Debye Institute, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands. w.k.kegel@uu.nl
Groenewold
Jan
J