Charged systems in, out of, and driven to equilibrium: from nanocapacitors to cement
Rudolf Podgornik, Chinese Academy of Sciences, rapporteur
René van Roij, Utrecht University, rapporteur
Emanuela del Gado, Georgetown University, examinatrice
Patrick Guenoun, CEA Saclay / CNRS, examinateur
Manoel Manghi, Université de Toulouse / CNRS, examinateur
Benjamin Rotenberg, Sorbonne Université / CNRS, examinateur
Emmanuel Trizac, Université Paris-Sud / CNRS, directeur de thèse
Most systems in soft matter are immersed in solutions with charged species: some can be described by mean-field theories, others require more sophisticated techniques. In this thesis defense we focus on two such systems.
Firstly, we analyze the relaxation dynamics of a nanocapacitor within the mean-field approach. We study relaxation times in the linear and nonlinear regime and characterize the behavior of the system as a function of salt density and applied voltage. The problem of designing a smart applied potential, to drive the system from an initial to a chosen final equilibrium state, is also tackled.
We then discuss the physics of ionic correlations in charged systems, with particular focus on the phenomenon of like-charge attraction. We show the relevance of the strong coupling theory, that we apply to the nanoscopic constituents of cement. We demonstrate that the strong cohesion force of cement may be explained by a “dry water” picture, in excellent agreement with molecular dynamics simulations, thereby filling a gap in our understanding of the most used synthetic material in the world.