One of the most important challenges in encapsulation is to prevent the immediate leakage of the encapsulated species. In this context, our strategy is to develop capsules by polymerizing the water phase of an oil-in-water-in-oil double emulsion. In other terms, our system consists in a direct emulsion of lipophilic species (O1) in a water phase (W) containing monomer, initiator and crosslinker. To obtain the double emulsion, this direct emulsion, stabilized by a hydrophilic surfactant, is itself dispersed in an external oil phase (O2) and stabilized by a lipophilic surfactant. The aim of the project is to polymerize the intermediate water phase to obtain a 3D network. The advantages of this system are that the polymerization will only take place in the water phase thanks to the solubility of the monomer and the obtained 3D network will play the role of an effective barrier limiting the diffusion of the inner lipophilic species. First of all, the feasibility of the double emulsion was studied. More specifically, we formulated several systems by varying the hydrophilic surfactant, the amount of oil O1 droplets inside the aqueous phase or the amount of hydrophilic surfactant inside the water phase. The second step of the study is to insert the polymerizable species in the double emulsion. We noticed that some monomers had interfacial affinity interfering with the formulation of the double emulsion and leading to a strong decrease of the number of inner droplets. We also focused on the coupling between formulation and processing and showed that shearing has to be chosen with care otherwise a simple reverse water-in-oil emulsion is obtained therefore leading to a loss of encapsulation capability.

Double emulsion for the encapsulation of reactive lipophilic components

254th National Meeting (2017)

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