Geoffrey Monet

Ecole Normale Supérieure de Paris | ENS · Département de Physique

In this work, we study the continuum theories of dipolar-Poisson models. Both the standard dipolar-Poisson model and the dipolar-Poisson–Langevin model, which keeps the dipolar density fixed, are non-convex functionals of the scalar electrostatic potential ϕ. Applying the Legendre transform approach introduced by Maggs [Europhys. Lett. 98, 16012 (2...

Recent experiments reporting a very low dielectric permittivity for nanoconfined water have renewed the interest in the structure and dielectric properties of water in narrow gaps. Here, we describe such systems with a minimal Landau-Ginzburg field theory composed of a nonlocal bulk-determined term and a local water-surface interaction term. We sho...

Recent experiments reporting a very low dielectric permittivity for nanoconfined water have renewed the interest to the structure and dielectric properties of water in narrow gaps. Here, we describe such systems with a minimal Landau-Ginzburg field-theory composed of a nonlocal bulk-determined term and a local water-surface interaction term. We sho...

Hypothesis: Synthetic imogolite nanotubes form stable colloidal dispersions that may also exhibit a rich liquid-crystalline phase behavior according to the nanotube length to diameter ratio. Anisometric double-walled aluminogermanate nanotubes are now readily available through hydrothermal treatment of germanium and aluminum precursors. This work a...

By combined use of Wide-Angle X-ray Scattering, Thermo-Gravimetric Analysis, Inelastic Neutron Scattering, Density Functional Theory and Density Functional Theory Molecular Dynamics simulations, we investigate the structure, dynamics and stability of the water wetting-layer at single-walled aluminogermanate imogolite nanotubes (SW Ge-INTs): an arch...

Ce travail de thèse est consacré à l’étude de nanotubes géo-inspirés des nanotubes d’imogolite naturels présents dans certains sols et à celle des propriétés dynamiques de l’eau dans ces objets. Les objets étudiés, de stoechiométrie Ge(Si)Al₂O₇H₄ et Ge(Si)Al₂O₆CH₆, sont des nanotubes d’aluminosilicate et d’aluminogermanate dont la paroi interne est...

In this article, we revisit the colloidal stability of clay imogolite nanotubes by studying the effect of electrostatic interactions on geo-inspired synthetic nanotubes in aqueous dispersions. The nanotubes in question are double-walled aluminogermanate imogolite nanotubes (Ge-DWINTs) with a well-defined diameter (4.3 nm) and with an aspect ratio a...

Determination of the atomic structure of inorganic single-walled nanotubes with complex stoichiometry remains elusive due to the too many atomic coordinates to be fitted with respect to X-ray diffractograms inherently exhibiting rather broad features. Here we introduce a new approach which enables resolution of their structure [1]. It is based, fir...

Determination of the atomic structure of inorganic single-walled nanotubes with complex stoichiometry remains elusive due to the too many atomic coordinates to be fitted with respect to X-ray diffractograms inherently exhibiting rather broad features. Here we introduce a new approach which enables resolution of their structure [1]. It is based, fir...

Determination of the atomic structure of inorganic single-walled nanotubes with complex stoichiometry remains elusive due to the too many atomic coordinates to be fitted with respect to X-ray diffractograms inherently exhibiting rather broad features. Here we introduce a methodology to reduce the number of fitted variables and enable resolution of...

Les nanotubes d’imogolite (NTI) sont des nanotubes d’oxydes métalliques de formule chimique (OH)4Al2O3SixGe1-x. Leur diamètre est de l’ordre du nanomètre, comme celui des célèbres nanotubes de carbone monoparois. Découverts en 1962 [1] et étudiés durant les années 70-80, les NTI sont l’objet d’un regain d’intérêt depuis la dernière décennie. Ils so...

Significant developments have been proposed over the last decade in the synthesis of aluminosilicate and aluminogermanate imogolite-like nanotubes. But while liquid phase synthesis is well controlled, it is not the case for imogolite or imogolite-like nanotube arrangement in dry state. In particular, nanotubes are found to self-assemble in bundles...