Cellulose nanocrystals (CNCs) are rod-like colloidal particles, which are increasingly considered for the stabilization of oil-in-water (o/w) or inverse water-in-oil (w/o) Pickering emulsions, with potential applications in cosmetics, biotechnology or material science. In these systems, the stabilization is imparted by the particles, which irreversibly absorb at the oil/water interface and form a rigid structure around the droplets. This typically requires an optimum balance between the solid-liquid and liquid-liquid interfacial tensions, which can be achieved by controlling the hydrophilic/hydrophobic balance at particles surface by chemical modification. In this context, esterified CNCs with tailored wetting properties were prepared and used to stabilize o/w and w/o Pickering emulsions, later applied for the design of polymer latexes or colloidosomes. The polymerization of monomer-in-water emulsions was conducted in the presence of a thermoactive initiator, leading the production of latexes composed of a mixture of microbeads and nanobeads, which could be easily separated by filtration/centrifugation. The nanobeads formation was partly attributed to the extrusion of monomer through the many holes resulting from the incomplete coverage of the emulsion droplets by the cellulose nanoparticles. In another approach, inverse w/o Pickering emulsions containing silica precursors were also prepared. The stabilized droplets were subsequently locked by cross-linking the precursors at the w/o interface, leading to an intricate network of polysiloxane within the cellulosic shell. In optimized conditions, the colloidosomes obtained displayed a robust and compact shell, which ensured a long-term encapsulation of rhodamine B or biological molecules such as fluorescent deoxyribonucleic acid (DNA).

Pickering emulsions stabilized by esterified cellulose nanocrystals: application to the elaboration of polymer latexes and colloidosomes

255th National Meeting (2018)

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