Encapsulation Process by Droplet Interface Crossing – EPIC

EPIC addresses the industrial scale development of an encapsulation process based on the generation of calibrated droplets of aqueous phase and their coating by crossing a liquid-liquid interface. The objective is to produce monodisperse capsules with controlled shell size, thickness and content. The project is based on the process cDICE (Continuous Droplet Crossing Encapsulation), Patent EP 2456550 A1, July, 2010) patented by one of the partners, which consists in forming droplets and forcing them by centrifugation to cross an interface between two immiscible liquids. The use of a centrifugal force allows a large range of flow regimes to be reached when crossing the interface, both in terms of centrifugal force and droplet deformation (Reynolds number and Bond number). The potential of the concept has been successfully explored for the production of vesicles (cDICE Project of the ANR Programme Emergence 2011-2014) and might be now extended to capsules production provided appropriate hydrodynamics running operations are used, i.e. inertial regime.

The project investigates the shell formation around the droplet and the stiffening of the shell to produce capsules of controlled thickness. The goal is to build a prototype fulfilling industrial requests in terms of capsule size (chosen ranges from 10 to 1000 ?m), shell thickness and productivity (about tens cm3/hour). The main scientific and technological locks are:
- The characterization of the mechanisms of droplet coating, at the single droplet scale, and their modelling according to physical and physical-chemical process parameters.
- The identification and modelling of the limiting phenomena when transposing the process from a single droplet to the diluted emulsion (multi-droplets): hydrodynamic interactions during the interface crossing, coalescence and stability of coated droplets
- The controlled transport of the capsules from the centrifugal environment to the hardening chamber to ensure the stability of the suspension, which is required to promote the establishment of a continuous process.
In addition, the stability of the diluted emulsion and the capsule suspension will be enhanced by the optimization of the formulation. This formulation, of utmost concern to guarantee stability and non-coalescence of droplets and capsules, will be thoroughly addressed and controlled throughout the whole process.
Experimental and numerical approaches will be developed to model the properties of the coated droplets according to the physicochemical and hydrodynamic process parameters. The project includes a multi scale and multi-disciplinary approach ranging from the study of the droplet coating mechanism to the development and implementation of a prototype.
Based on the development and the extrapolation of an innovative process, the project perfectly enters the frame of the DEFI 3 «stimuler le renouveau industriel», axe 3 «matériaux et procédés multifonctionnels multi-échelles ».