Understanding of the stability mechanisms of water-in-water Pickering emulsions for catalytic applications

Unlike conventional emulsions stabilized by surfactant molecules, Pickering emulsions are stabilized by nanoparticles. Because of their extreme stability to coalescence, they find numerous applications in several industries (agrifood, pharmaceuticals, chemical industry). In recent years, the applications of these emulsions in catalysis have been increasingly studied, for the development of continuous two-phase processes. In a context of decarbonization and transition to more environmentally friendly processes, we want to explore new applications in conditions free of any solvent other than water.
Water-in-water emulsions are colloidal dispersions of two immiscible aqueous phases at thermodynamic equilibrium. These emulsions are formed from aqueous solutions of two incompatible water-soluble molecules in solution, such as mixtures of polymers or polymer/electrolyte. These mixtures are mainly used for the extraction of macromolecules in complex biological mixtures, the separation of cells, membranes, proteins, and other biomolecules. They are particularly suitable for the recovery of products in biotechnology (such as sugars). However, because of the ultra-low interfacial tensions that characterize these systems, it is particularly difficult to stabilize the emulsions. In particular, it is impossible for small hydrophilic surfactant molecules to adsorb at the interface. On the other hand, an effective way to block the coalescence of w/w emulsions is to use solid particles.
In this thesis, we propose to experimentally study the mechanisms of stabilization of Pickering w/w emulsions (impact of the nature, morphology, and wettability of the particles) in order to acquire a better control of their formulation for their implementation in catalytic/enzymatic processes.

Keywords: Water-in-water emulsion, Pickering, nanoparticles, interfaces, catalysis

• Academic supervisor    Dr, HDR, DALMAZZONE Christine, IFPEN,  https://orcid.org/0000-0002-2567-9385 
• Doctoral School    ED388, http://ed388.sorbonne-universite.fr/fr/index.html 
• IFPEN supervisor    Dr, HDR, DALMAZZONE Christine, Applied Physical Chemistry and Mechanics, christine.dalmazzone@ifpen.fr , https://orcid.org/0000-0002-2567-9385
• PhD location     Physical Chemistry of Complex Materials and Fluids, Rueil-Malmaison, France
• Duration and start date    3 years, starting in fourth quarter 2023
• Employer    IFPEN, Rueil-Malmaison, France 
• Academic requirements    University Master degree in relevant disciplines: Colloids, soft matter, physico-chemistry of interfaces, formulation…
• Language requirements    Fluency in French or English, willingness to learn French
• Other requirements    Knowledge of catalysis/biocatalysis appreciated