Investigating swelling-breakdown in double emulsions

Dilute water-in-oil-in water double emulsions are prepared to investigate the release and swelling phenomena during preparation and storage. During storage, a specific attention is paid to detect the overswelling-breakdown phenomenon that is due to overswelling of the outer droplets which causes their breakage and abrupt release of the inner droplets. A swelling ratio of the outer droplets is defined and is found useful to identify the effect of different parameters on the swelling behavior of the double emulsions. Yet, the investigation of the full droplet size distribution remains necessary. Before overswelling-breakdown, the escape is governed by the Brownian motion of the inner droplets and their coalescence with the external phase through the surface of the outer droplets. The swelling rate is mainly governed by the osmotic gradient between the internal and external water phases.