Emulsification in viscoelastic media

We have created stable monodisperse emulsions by shearing and rupturing crude polydisperse emulsions of larger droplets into smaller droplets having a unique size. To eliminate inhomogeneous fracture flow which can lead to nonuniform rupturing and broad polydispersity, we use a shearing geometry with a narrow gap. We can control the final droplet size by altering the shearing conditions and the emulsion's viscoelasticity which depends on its composition. We argue that the high degree of monodispersity, indicated by Bragg scattering from colloidal crystals of droplets, may result from a capillary instability that includes the role of the emulsion's viscoelasticity.