Collective Effects in Ionic Liquid [emim][Tf2N] and Ionic Paramagnetic Nitrate Solutions without Long-Range Structuring.

Mesoscopic shear elasticity has been revealed in ordinary liquids both experimentally by reinforcing the liquid/surface interfacial energy and theoretically by nonextensive models. The elastic effects are here examined in the frame of small molecules with strong electrostatic interactions such as room temperature ionic liquids [emim][Tf2N] and nitrate solutions exhibiting paramagnetic properties. We first show that these charged fluids also exhibit a nonzero low-frequency shear elasticity at the submillimeter scale, highlighting their resistance to shear stress.

Highlighting Thermo-Elastic Effects in Confined Fluids.

The recent identification of a finite shear elasticity in mesoscopic fluids has motivated the search of other solid-like properties of liquids. We present an innovative thermal approach of liquids. We identify a dynamic thermo-elastic mesoscopic behavior by building the thermal image produced by different liquids upon applying a low frequency mechanical shear field.

Identification of Thermal Response of Mesoscopic Liquids under Mechanical Excitation: From Harmonic to Nonharmonic Thermal Wave.

In the conventional picture, the temperature of a liquid bath in the quiescent state is uniform down to thermal fluctuation length scales. Here we examine the impact of a low-frequency shear mechanical field (hertz) on the thermal equilibrium of polypropylene glycol and liquid water away from any phase transition confined between high-energy surfaces. We show the emergence of both cooling and heating shear waves of several tens of micrometers widths varying synchronously with the applied shear strain wave.

Strain-induced violation of temperature uniformity in mesoscale liquids.

Thermo-elasticity couples the deformation of an elastic (solid) body to its temperature and vice-versa. It is a solid-like property. Highlighting such property in liquids is a paradigm shift: it requires long-range collective interactions that are not considered in current liquid descriptions.