The effect of flow on viscoelastic emulsion microstructure.

Emulsions made of oil, water and surfactants are widespread soft materials with complex structures depending on composition and temperature. Emulsion phase behavior at rest has been widely investigated but flow-induced effects, which are very relevant in many applications, can still be further explored towards improved emulsion microstructural design. In this work, we use low energy emulsification processing to create small-sized emulsions. In a previous report, we showed the emulsion morphology development and the effect of flow on the microstructure of a highly viscoelastic attractive emulsion which result in a concentrated nanoemulsion after viscoelastic droplet filaments are disrupted. Here, we show that upon stopping the flow, the filaments slowly buckle, recoil and finally form clusters of randomly flocculated droplets. We thus obtain two completely different emulsion morphologies simply induced by the action of flow, where in both cases attractive interactions play a key role. The emulsion high interfacial area represents a valuable feature for several applications such as upstream operations, microreaction media and drug delivery.