Pr. Valérie Ravaine
Institut des Sciences Moléculaires, UMR 5255, Université de Bordeaux – CNRS
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Microgels: soft and responsive colloids with special behavior in suspension and at interfaces
Nano- and microgels are colloidal particles made of lightly cross-linked polymer swollen by a solvent. Microgels are often stimuli-responsive, as they can undergo volume phase transition implying their total or partial deswelling upon changes like temperature, pH or the presence of an analyte. As such, they belong to the category of soft and deformable particles, which confer them some specific properties compared to hard particles. In suspension, their phase diagram is richer than that of hard colloids, because their repulsive interaction potential changes gradually with decreasing the center-to-center distance between microgels. Many microgels also adsorb at liquid interfaces and present the ability to act as stabilizers in foams and emulsions. Again, deformability imparts original features to microgel-laden interfaces. Moreover, owing to the polymer-colloid duality, studying these structures is a mean to question the continuous landscape of architectures, from the hard particles to linear polymers. We will discuss about the behavior of microgels at liquid interfaces, from the microgel structure and their organization to their mechanical properties. We will show examples of original applications that can derive from these concepts and the extension to water-in-water emulsions.
