The degree of sisociation of ionicsurfactant shells within a W/O microdroplet

摘要

The degree of dissociation of ionic surfactant shells within a W/O microdroplet is investigated on the basis of the Poisson- Boltzmann equation and lacally ideal mixing assumption. The degree of dissociation is the result of the competition between the entropy associated with count.erions in the aqueous core and mixing of surfactant ions with associated surfactants on the shell, and the electrostatic energy. The degree of dissociation is found to depend on the geometry and is in the order: Two planar surfaces >cylinder> sphere of the same size. Moreover, for the same geometry, the degree of dissociation increases with the size Qf thedfoplet.. The free energy chang~ associated with a droplet due to dissociation is obtained. The effect of the solubilization ofa neutral particle on the degree of dissociation is also studied. The solubilization is found to hinder the dissociation.