Simulation of common features and differences of surfactant-based and solid-stabilized emulsions

A continuum model is used to study thermodynamical stability of surfactant-based and solid-stabilized emulsions. Both modeling approaches are based on a phase-field description. In the case of solid particles along the fluid–fluid interface a local approximation to a classical dynamic density functional theory is used to account for particle–particle interactions. This allows for attractive as well as repulsive interactions. Coarsening studies are performed, which demonstrate thermodynamic stability for both cases. For surfactant-based emulsions this is achieved by a drastic reduction of surface tension, whereas for solid-stabilized emulsions the same effect results from an elastic force. Both types of emulsions behave different if a macroscopic force is applied. This is demonstrated by a rigid body interacting with the emulsion. The surfactant-based emulsion behaves like a fluid, whereas the solid-stabilized emulsion shows properties of a solid with a finite elastic modulus and a yield stress.