the largest phase will often become the continuous phase. However, highly concentrated emulsions (looking like 'liquid-liquid foams') can also be obtained and stabilized. Stability Macroemulsions are, by definition, not thermodynamically stable. This means that from the moment they are created, they are always reverting to their original, immiscible and separate state. The reason why Macroemulsions can exist however, is because they are kinetically stable rather than thermodynamically stable. This means that, while they are continuously breaking down, it is done at such a slow pace that it is practically stable from a macroscopic perspective. The reasons why macroemulsions are stable is similar to the reasons why colloids can be stable. Based on DLVO theory, repulsive forces from the charged surfaces of the two phases repel each other enough to offset the attractive forces of the Hamaker Force Interactions. This creates a potential energy well at some distance, where the particles are in a local area of stability despite not being directly touching and therefore coalescing. However, since this is an area of local rather than total low potential, if any set of particles can randomly have enough thermal energy they can coalesce into an even more stable state, which is why all macroemulsions gradually coalesce over time. While it is energetically favorable for individual particles to coalesce due to the subsequent reduction of interfacial area, the adsorbed emulsifier prevents this. This is because it is more favorable for the emulsifying agent to be at an interface so reducing the interfacial area requires expending energy to return the emulsifying agent to the bulk. Stability of the Macroemulsions are based on numerous environmental factors including temperature, pH, and the ionic strength of the solvent. Progression of macroemulsions Flocculation Flocculation occurs when the dispersed drops group together throughout the continuous phase, but don't lose their individual identities. The driving force for flocculation is a weak van der Waals attraction between drops at large distances, which is known as the secondary energy minimum. An electrostatic repulsion between the surfaces prevents the drops from touching and merging, stabilizing the macroemulsion. The rate of diffusion limited encounters is equal to the upper limit for the decrease in droplet concentration and can be represented by the following equation: where D can be found using the Stokes-Einstein relation , R is the droplet radius, and c is the number of droplets per unit volume. This equation can be