How colloid nature drives the interactions between actinide and carboxylic surfactant in sol: Towards a mesostructured nanoporous actinide oxide material
Journal of Colloid and Interface Science
Effect of alkyl chain configuration of tertiary amines on uranium extraction and phase stability – Part I: Evaluation of phase stability, extraction, and aggregation properties
Journal of Molecular Liquids, 2021
Predicting Microemulsions Stability, Viscosity and Cloud Points of Micelles via Spontaneous and Effective Packing Competition
Proceedings of the Virtual 2020 AOCS Annual Meeting & Expo, 2020
Bending: from thin interfaces to molecular films in microemulsions
Current Opinion in Colloid & Interface Science, 2020
Abstract Surfactant film rigidity is a ubiquitous general concept that is quantified in two diffe... more Abstract Surfactant film rigidity is a ubiquitous general concept that is quantified in two different units. We show here how to convert the bending rigidity from reduced units of a virtual infinitely thin film (not made of molecules) into the chemical unit (kJ.mol-1) of a realistic film of monomolecular thickness. In most cases molecular lengths are not negligible versus curvature radius. Two bending constants for the elasticity of thin-shelled solids can be defined, as introduced by Gauss, whereas only one physical bending constant taking into account that the film cannot be teared has been introduced in the nineties by Hyde and Ninham. The explicit conversion depends on the topology and is different in the quasi-planar approximation, as well as the “direct” o/w or “reverse” w/o case of spherical or cylindrical micelles. We show some examples for classical and nonclassical micelles and microemulsions of different topologies in (H,N coordinates).
Structured solvent effects on precipitation
Colloid and Polymer Science, 2017
The synthesis of cerium oxalate, a reaction intermediate in the preparation of high performance c... more The synthesis of cerium oxalate, a reaction intermediate in the preparation of high performance ceramics, is studied in sessile droplets. We compare here the effect of alcoholic solvents with the usage of structured solvents, namely ultra-flexible microemulsions in the water-rich and oil-rich configurations. The nucleation and the growth of cerium oxalate particles are the result of local mixing by the Marangoni flow of droplets loaded with oxalic acid and cerium nitrate. The morphology of the particles is very different depending on the composition of the solvent and on the mixing process. We show that the variation of the particle morphology results from the difference of the structured solvent microphases during the precipitation process. When the precipitation occurs in a water continuous phase, usual needle-like oxalate particles precipitate. When the precipitate is formed in the dispersed phase of the emulsion, structured aggregates, as close-packed aggregates of needles, are compacted by microcapillarity effects.
Experimental evidence for bicontinuous structures in L 3 phases
Progress in Colloid & Polymer Science
ABSTRACT Anomalous flow birefringent phases, sometimes designated as L 3, have been identified in... more ABSTRACT Anomalous flow birefringent phases, sometimes designated as L 3, have been identified in both the water-rich and the oil-rich parts of the phase diagram of the water(-NaCl)-dodecane-pentanol-SDS system. The presence of these phases appear to be associated with that of swollen lamellar phases. Conductivity and neutron-scattering results provide evidence that the structure of these phases consists of a highly connected, sponge-like, random bilayer-continuous surface. The surfactant surface separates, depending upon the system, into either two water-continuous domains or two oil-continuous domains. The data are consistent with a recent theoretical model.
Scattering as a critical test of microemulsion structural models
Progress in Colloid & Polymer Science
Page 1. Progress in Colloid & Polymer Science Progr Colloid Polym Sci 81:20-2... more Page 1. Progress in Colloid & Polymer Science Progr Colloid Polym Sci 81:20-29 (1990) Scattering as a critical test of microemulsion structural models TN Zemb, IS Barnes, P.-J. Derian, and BW Ninham Abstract: Current models of microemulsion microstructure are reviewed and their predictive power tested by comparison between their predictions and scattering from some typical concentrated ternary microemulsions. Key words: M_ icroemulsion; m_ icrostructure; c_urvature; D_DAB; V_ oronoi Introduction ...
Extractant Molecules as Hosts in Surfactant Monolayers or Bilayers
From Basic Research to Application, 2014
International audienc
Using Microemulsions: Formulation Based on Knowledge of Their Mesostructure
Chemical Reviews, 2021
Microemulsions, as thermodynamically stable mixtures of oil, water, and surfactant, are known and... more Microemulsions, as thermodynamically stable mixtures of oil, water, and surfactant, are known and have been studied for more than 70 years. However, even today there are still quite a number of unclear aspects, and more recent research work has modified and extended our picture. This review gives a short overview of how the understanding of microemulsions has developed, the current view on their properties and structural features, and in particular, how they are related to applications. We also discuss more recent developments regarding nonclassical microemulsions such as surfactant-free (ultraflexible) microemulsions or ones containing uncommon solvents or amphiphiles (like antagonistic salts). These new findings challenge to some extent our previous understanding of microemulsions, which therefore has to be extended to look at the different types of microemulsions in a unified way. In particular, the flexibility of the amphiphilic film is the key property to classify different microemulsion types and their properties in this review. Such a classification of microemulsions requires a thorough determination of their structural properties, and therefore, the experimental methods to determine microemulsion structure and dynamics are reviewed briefly, with a particular emphasis on recent developments in the field of direct imaging by means of electron microscopy. Based on this classification of microemulsions, we then discuss their applications, where the application demands have to be met by the properties of the microemulsion, which in turn are controlled by the flexibility of their amphiphilic interface. Another frequently important aspect for applications is the control of the rheological properties. Normally, microemulsions are low viscous and therefore enhancing viscosity has to be achieved by either having high concentrations (often not wished for) or additives, which do not significantly interfere with the microemulsion. Accordingly, this review gives a comprehensive account of the properties of microemulsions, including most recent developments and bringing them together from a united viewpoint, with an emphasis on how this affects the way of formulating microemulsions for a given application with desired properties.
Facile Preparation of Macro-Microporous Thorium Oxide via a Colloidal SolGel Route toward Safe MOX Fuel Fabrication
Swollen cubic lyotropic ternary phases with Pn3m symmetry and reduced hardness were obtained from... more Swollen cubic lyotropic ternary phases with Pn3m symmetry and reduced hardness were obtained from a specific binary mixture of cubic phase-forming (phytantriol) and lamellar phase-forming (decaglycerol monooleate) compounds. The microstructures were determined by using a small-angle x-ray scattering technique. The softness and temperature-induced phase transitions were investigated by means of rheology. The incorporation of a surface-active fragrance compound (linalool) at concentrations up to 6 wt. % induced a structural transition toward a softer Im3m bulk cubic phase with longer water channels. Higher linalool concentrations allowed for the spontaneous dispersion of the bulk cubic phase into microscopic particles with a cubic structure (cubosomes).
The characterization of nanoporous powders of highly absorbing compounds by small-angle X-ray sca... more The characterization of nanoporous powders of highly absorbing compounds by small-angle X-ray scattering (SAXS) involves overcoming several difficulties before quantitative information related to the porous texture, such as the specific surface and the porous volume, can be derived. In this article, first, the contribution of the grain facet reflectivity and scattering from the bulk of a grain with the density of ThO2, a highly absorbing material, were calculated. Microporous ThO2 powder having micrometric grain size was characterized, in which the scattering signal is predominant. A high-resolution synchrotron instrument was used in order to cover a wider q range and minimize the absorption effect, and the results were compared with those obtained using a laboratory X-ray source. Concerning the absorption problem existing with a laboratory X-ray source, a new and robust experimental method was proposed to correctly determine the scattering intensity of the highly absorbing granular...
Mechanism of calcium phosphates precipitation in liquid crystals
Apparatus for the measurement of chemical activity coefficients of gas phase species in thermodynamic equilibrium with liquid phase
HAL (Le Centre pour la Communication Scientifique Directe), Oct 25, 2017
The invention relates to an apparatus comprising a fluidic part (10) intended to contain a sample... more The invention relates to an apparatus comprising a fluidic part (10) intended to contain a sample; an analytical part (30) comprising a waveguide (32); and a permeable membrane (20) closing the fluidic part (10), so as to physically separate the fluidic part (10) from the analytical chamber (30)
Phenomena associated to the transfer of rare earths involved in separation chemistry: from the molecular modelling to chemical engineering
Recycling of metals, such as rare earths, into valuable material relies on ion specific separatio... more Recycling of metals, such as rare earths, into valuable material relies on ion specific separation, basis of the hydrometallurgy. Most of efficient methods known for separating ions are based on equilibria between complex fluids, typically between aqueous and organised organic phases. Indeed, ions migrate from the aqueous to the organic phase thanks to surfactant or extractant molecules in the organic phase, and then are captured in reverse micelles. Understanding the driving forces of the ion transfer is therefore a crucial issue to understand the properties of liquid liquid interfaces between organic and aqueous phases, but also to assess the chemical potentials of the compounds involved. Here, we propose multi-scale approaches for calculating thermodynamics properties of ions in aqueous and organic phases directly comparable to the experiments ones only by taking into account the molecular properties of the solutes with no adjustable parameters. Based on the osmotic equilibrium m...
Current Opinion in Colloid and Interface Science, 2016
Étude Structurale De Solutions Micellaires Concentrées
Nous avons etudie la structure des micelles binaires savon-eau concentrees en comparant les mesur... more Nous avons etudie la structure des micelles binaires savon-eau concentrees en comparant les mesures de diffusion de lumiere, de neutrons et de rayons X ainsi que la relaxation induite par des ions paramagnetiques absorbes a l’interface. Ces techniques nous ont permis de mettre en evidence la variation systematique de la masse des micelles en fonction de la concentration ainsi que l’hydratation des tetes polaires. L’interface eau-huile est lisse : l’eau ne penetre pas dans le cœur. Les fluctuations de l’interface en entrainent un desordre complet des chaines hydrocarbonees du cœur. Ces methodes, une fois calibrees, sont etendues a des systemes ternaires. Nous avons montre que les molecules de cosurfactant pentanol ne sont astreintes a l’interface que pour de faibles concentrations. Par variation de pH, nous avons montre l’invariance de la densite surfacique de charge electrique, independante de larges variations du pouvoir de solubilisation. Enfin, l’etude des perturbations du rayon ...
Stiff and flexible water-poor microemulsions: disconnected and bicontinuous microstructures, their phase diagrams and scattering properties
We generate all possible thermalized microstructures of two non miscible liquids separated by a k... more We generate all possible thermalized microstructures of two non miscible liquids separated by a known amount of w/o interface and locate their domains of stability in ternary phase diagrams. Frus- trated and unfrustrated bicontinuous microemulsions appear near instabilities related to transition towards lyotropic liquid crystals. Microstructures can be distinguish via qualitative features on the scattering.
Uploads
Papers by Thomas Zemb