The coalescence of monodisperse silicone oil-in-water emulsions stabilized with sodium dodecyl sulfate has been studied. We report the existence of a sharp destabilization threshold, controlled by surfactant chemical potential, osmotic pressure, and droplet diameter, at which the rate of coalescence increases dramatically. We present evidence that the stability of the emulsions can be characterized by two microscopic parameters: a minimum stable value of the surfactant chemical potential and a maximum value of the pressure exerted upon a droplet-droplet interface.

• Received 5 June 1992

DOI:https://doi.org/10.1103/PhysRevLett.69.2439