HDR: On the edge of continuous - Cyril Picard (LIPhy)

Confined fluids have been the theme of my research for the past ten years. In particular, they play a major role in fresh water production processes by desalination of seawater and in reverse processes, designed for the recovery of non-intermittent renewable energy, known as osmotic energy. The phenomena of selective transport of solvent and solutes under confinement are at the heart of these systems. The work carried out in the field of what is now called nanofluidic has made it possible to elucidate some of the physical mechanisms involved by experimentally relying on the use of specific confining materials (graphene, boron nitride, nanotubes, etc.).
This exploration is subject to many instrumental constraints. It also remained mainly confined to the case of single-phase transport. As an example, the measurement of minute flows within a nanopore is still a challenge.  In a first part, the work I will present aims to meet this challenge. Beyond monophasic situations, the central part of my presentation is dedicated to the study of wetting in nanometric to subnanometric pores. To this end, an original dynamic porosimetry approach is used to characterize the forced imbibition and drying processes in hydrophobic ordered nanoporous structures. In this context, the contribution of the line tension, characteristic of the free energy of the contact line, and its possible alteration by line surfactants is discussed.
The last part of my presentation is focused on the impact of solutes and the lighting that could bring a new method of dynamic calo-porosimetric measurement. I will also sketch two avenues considered in the laboratory as new ways of harvesting osmotic energy based on the control of transport in fluid medium at the borders of the continuous.

Members of the jury :

Isabelle Cantat - Professeure des Universités - Université de Rennes - rapportrice
Denis Morineau - Directeur de Recherche - CNRS délégation Bretagne et Pays de la Loire - rapporteur
Isabelle Beurroies - Professeure des Universités – Aix-Marseille Université - rapportrice
Thierry Ondarçuhu - Directeur de Recherche - CNRS délégation Occitanie ouest - examinateur
Frédéric Restagno- Directeur de Recherche - CNRS délégation Île-de-France-sud - examinateur
Christian Geindreau - Professeur des Universités - Université Grenoble Alpes - examinateur