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Accueil > Équipes > Matière molle : Organisation, Dynamique et Interfaces > Thèmes de Recherche


par Elise Lorenceau - publié le , mis à jour le

Nano-mechanics of Ionic Liquids
(Elisabeth CHARLAIX, Benjamin CROSS )

Ionic liquids are special electrolytes, solvent-free and highly concentrated. They are molten salts at room temperature. Their applications are numerous in the energy fields (batteries, capacitors and other electrical systems), mechanical (they are excellent lubricants) or environmental (pollution control). All these applications are based on the properties of ionic liquids at interfaces or under confinement. We have shown that in the vicinity of an interface, ionic liquids are arranged in layers and we have measured the mechanical properties of these molecular size layers. The presence of these layers strongly influences the flow of ionic liquids to sizes relevant for the applications. This type of study makes it possible to better understand the link between structure and dynamics, an essential link for a fine prediction of the behavior of ionic liquids.

Nano-rheology and friction of confined liquids
(Elisabeth CHARLAIX, Benjamin CROSS in coll. with C. Cottin-Bizonne at ILM Lyon)

The rheological properties of ultra-confined liquids down to some molecular layers is the subject of many questions and controversies. We use dynamic Surface Force Measurements to study the nano-rheology of simple and complex liquids at a nano-scale, in the range of some Hz to 300 Hz. By varying the thickness of a liquid film between a sphere and a plane, its bulk and interfacial responses can be disantangle, giving access to the liquid modulus and its friction onto the solid surface (slippage, or non-flowing layer at wall). This work has made the cover of Phys. Rev. Lett.

Nano-mechanics of soft thin films
(Elisabeth CHARLAIX, Benjamin CROSS)

We have developped an original method to probe the visco-elastic properties of soft materials without contact. We use a squeeze flow to indent the soft layer, and an elasto-hydrodynamic theory to extract its Young Modulus and loss modulus. The soft layer is not modified by the contact with an external probe. We use this method to study polymer brushes, hydrogels and cell mechanics in collaboration with other teams in Liphy, LPS in Orsay, and Prof. Tong in Hong-Kong.