Surfactants have a strong effect in reducing the surface tension between the water and the air, as well as the interfacial tension between the water and otherwise immiscible liquids such as vinyl monomers. The practical fact that commercial emulsion polymerizations can be run smoothly and quite rapidly with many water-insoluble monomers is due to the presence of surfactants. Normally, surfactants are used in concentrations well above their critical micelle concentration (CMC). At such practical concentrations, surfactants form micelles, which are entities capable of  “solubilizing” non-polar substances like organic monomers.

A critical issue in commercial latex manufacture is their stability during and after production. As mentioned, surfactants have an effect on overall latex stability. Thus, the appropriate surfactant selection is an important consideration when designing a latex formulation. Anionic and nonionic are the most effective and widely used surfactants in emulsion polymerization. While anionic surfactants prevent coagulation due to electrostatic repulsions, nonionic surfactants prevent coagulation due to steric stabilization. Anionic surfactants prevent coagulation by electrostatic repulsions originated from the anionic charges adsorbed on the polymer particles and their associated double layers. And nonionic surfactants, especially polyethoxylates, prevent coagulation by spatial or steric stabilization. Some specialty surfactants, such as fatty alcohol ether sulfates, Disponil® FES, combine both, electrostatic and steric stabilization in their molecules.