Institut Charles Sadron Event

The Continuous Droplet Interface Crossing Encapsulation (cDICE) is a method for producing either giant unilamellar vesicles or shell/core capsules. In this process, droplets of the aqueous liquid to be encapsulated are continuously produced in a non-aqueous liquid (phase 1) and driven across a liquid/liquid interface using an external force such as a centrifugal force. When the inertia of the droplet is small compared to the interfacial forces, and in presence of amphiphilic molecules in phase 1, zipping of the two amphiphilic molecules monolayers encountering when a droplet reaches the interface, drives the crossing and vesicles can be produced at high rate. At high inertia, droplets deform the liquid/liquid interface and each droplet entrain a volume of phase 1 which will constitute the shell of the final capsule. We have experimentally studied encapsulation of a droplet by crossing a liquid-liquid interface (oil-water) under centrifugal force using high-speed imaging for a wide range of process parameters and physical properties of the liquids, represented by seven non-dimensional numbers. We obtained the conditions for crossing, that we mapped in a graph of density contrast ratio versus interfacial Bond number, Bo (buoyancy force to the interfacial tension ratio). We also explored the effect of fluid properties on the dynamics of pinch-off of the entrained liquid column, which fixes the final shell volume. The two mechanisms of microencapsulation and their application, from the use of vesicles up to the microcapsules will be discussed.