Marianne Impéror-Clerc

• Managing Director at French National Centre for Scientific Research

Since the morphology of nanoparticles directly influences many of their properties, accurately determining their shape is crucial for targeted applications. In this work, we focus on nanoprisms due to their widespread use and the limitations of direct imaging techniques in accurately describing their polygonal cross section. Specifically, we introd...

The recently discovered chiral monotile Tile(1,1) is tiling the plane in a quasiperiodic fashion by taking twelve different orientations when applying $2\pi/12$ rotation. An homochiral inflation construction of such a quasiperiodic tiling is proposed where the chirality of the monotile is completely fixed at all inflation steps, avoiding to exchang...

Square-triangle-rhombus ($\mathcal{STR}$) tilings are encountered in various self-organized multi-component systems. They exhibit a rich structural diversity, encompassing both periodic tilings and long-range ordered quasicrystals, depending on the proportions of the three tiles and their orientation distributions. We derive a general scheme for ch...

Abstract – A grid method using tiling by fundamental domain of simple bi-dimensional lattices is presented. It refers to a previous work done by Stampfli in 1986 using two grids by regular hexagons, one rotated by π/2 relatively to the other. This leads to a quasiperiodic structure with a twelve-fold symmetry made of regular triangles, squares and...

A grid method using tiling by fundamental domain of simple 2D lattices is presented. It refer to a previous work done by Stampfli in $1986$ using two tilings by regular hexagons, one rotate by $\pi/2$ relatively to the other. This allows to get a quasiperiodic structure with a twelve fold symmetry. The quasiperiodic structure is a tiling of the pla...

Depletion‐induced self‐assembly is routinely used to separate plasmonic nanoparticles (NPs) of different shapes, but less often for its ability to create supercrystals (SCs) in suspension. Therefore, these plasmonic assemblies have not yet reached a high level of maturity and their in‐depth characterization by a combination of in situ techniques is...

Hard spheres are one of the most fundamental model systems in soft matter physics, and have been instrumental in shedding light on nearly every aspect of classical condensed matter. Here, we add one more important phase to the list that hard spheres form: quasicrystals. Specifically, we use simulations to show that an extremely simple, purely entro...

Packing solid shapes into regular lattices can yield very complex assemblies, not all of which achieve the highest packing fraction. In two dimensions, the regular pentagon is paradigmatic, being the simplest shape that does not pave the plane completely. In this work, we demonstrate the packing of plasmonic nanoprisms with pentagonal cross section...

We report the two-dimensional self-assembly at the liquid-air interface of spherical gold nanoparticles (NPs) with diameters between 2 and 14 nm. By exploring the self-assembly conditions, such as the dispersing solvent and the coating ligand (thiols with different lengths, oleylamine, polystyrene), we identify suitable conditions for long range cl...

We report on High Pressure Small Angle X-ray Scattering (HP-SAXS) measurements on 3D face-centered cubic (FCC) supracrystals (SCs) built from spherical gold nanoparticles (NPs). Dodecane-thiol ligands are grafted on the surface and ensure the stability of the gold NPs by forming a protective soft layer. Under a hydrostatic pressure of up to 12 GPa,...

Pentagonal packing is a long‐standing issue and a rich mathematical topic, brought to the fore by recent progress in nanoparticle design. Gold pentagonal bipyramids combine five‐fold symmetry and anisotropy and their section varies along the length. In this work, we obtain colloidal supercrystals of pentagonal gold bipyramids in a compact arrangeme...

Quasicrystals are fascinating structures, characterized by strong positional order but lacking the periodicity of a crystal. In colloidal systems, quasicrystals are typically predicted for particles with complex or highly specific interactions, which makes experimental realization difficult. Here, we propose an ideal colloidal model system for quas...

We report a seed-mediated synthesis strategy to control the size of gold nanoparticles at the atomic scale in the 2-5 nm size range. Starting from 2 nm seeds, a regrowth...

Regular square and triangle, two very simple geometrical figures, can be used to construct a fascinating variety of tilings which cover the 2D plane without any overlaps or holes. Such tilings are observed in many soft matter systems. Here we present a way to describe all possible globally uniform square-triangle phases using a three dimensional co...

Nanocrystals, used as building blocks, may self-assemble in long-range ordered assemblies socalled supracrystals. Different structures FCC, BCC but also Frank-Kasper phases have been observed and the roles of the soft ligands surrounding the rigid crystalline cores in the self-assembly process is not yet well understood and need further study. The...

Many soft matter systems are composed of roughly spherical objects that can self-assemble in ordered structures. Unlike hard spheres, at high volume fraction these soft spheres adapt their shape to the local geometrical constraints and the question of space filling needs to be entirely revisited. Hydrophobically coated gold nanocrystals self-assemb...

Organizing nanoparticles (NPs) into periodic structures is a central goal in materials science. Despite progress in the last decades, it is still challenging to produce macroscopic assemblies reliably. In this work, the analysis of the pervaporation‐induced organization of gold octahedra into supercrystals within microfluidic channels using a combi...

The catalytic hydrogenation of CO2 to formic acid is one of the most promising pathways towards a renewable hydrogen-storage system. The reaction is usually performed in aqueous phase in the presence of basic molecules over homogeneous or heterogeneous catalysts, generating relatively dilute formate solutions (<1 M). The newly designed solid micell...

The process of colloidal drying gives way to particle self-assembly in numerous elds including photonics or biotechnology. Yet, the mechanisms and conditions driving the nal particle arrangement in dry colloidal layers remain elusive. Here, we examine how the drying rate selects the nanostructure of thick dried layers in four dierent suspensions of...

The process of colloidal drying gives way to particle self-assembly in numerous fields including photonics or biotechnology. Yet, the mechanisms and conditions driving the final particle arrangement in dry colloidal layers remain elusive. Here, we examine how the drying rate selects the nanostructure of thick dried layers in four different suspensi...

The fate of plastic waste is a pressing issue since it forms a visible and long-lived reminder of the environmental impact of consumer habits. In this study we examine the structural changes in the lamellar arrangements of semi-crystalline polyethylene (PE) packaging waste with an aim to understand the physical mechanisms of embrittlement in PE exp...

Grazing incidence X-ray diffraction (GIXD) studies of monolayers of biomolecules at an air–water interface give quantitative information of in-plane packing, coherence length of crystalline domains, etc. Rheo-GIXD measurements can reveal quantitative changes in the nanocrystalline domains of a monolayer under shear. Here, we report GIXD studies of...

Grazing Incidence X-ray Diffraction (GIXD) studies of monolayers of biomolecules at the air-water interface give quantitative information of in-plane packing, coherence lengths of the ordered (diffracting) domains and orientation of hydrocarbon chains of the model membranes. Rheo-GIXD measurements revel quantitative changes in the monolayer under s...

The ϵ‐Fe2O3 polymorph of iron oxide, which has outstanding physical properties, is successfully stabilized inside mesoporous silica particles with tailored shapes. Using mesoporous silica particles with three different morphologies of rod, platelet and donut, we obtain ϵ‐Fe2O3/mesoporous silica nanocomposites. Iron oxide is loaded inside the porosi...

A solid state perspective on the degradation of polyethylene in the ocean Christopher J. Garvey1,2, Martin Kreuzer3, Gwénaël Gouadec4, Stéphan Rouzière1, Marianne Impéror1, Anne Françoise Mingotaud5 and Alexandra ter Halle5 1. Laboratoire de Physique des Solides, UMR CNRS 8502, Université Paris-Sud, Université Paris Saclay, 91405 Orsay Cedex , Fra...

The self-assembly of amphiphilic molecules usually takes place in a liquid phase, near room temperature. Here, using small angle X-ray scattering (SAXS) experiments performed in real time, we show that freezing of aqueous solutions of copolymer amphiphilic molecules can induce self-assembly below 0{\deg}C.

In this paper, the disintegration of starch (waxy and standard starch) granules into nanosized particles under the sole effect of high power ultrasonication treatment in water/isopropanol is investigated, by using wide methods of analysis. The present work aims at a fully characterization of the starch nanoparticles produced by ultrasonication, in...

Integration of coordination polymers and metal organic frameworks into real applications requires a processing step at the nanoscale while their synthesis in the form of nanoparticles with controlled size, shape and organization remains a challenge faced by diverse scientific communities. Ordered mesoporous silica monolith with 2D-hexagonal structu...

The self-assembly of amphiphilic molecules usually takes place in a liquid phase, near room temperature. Here, using small angle X-ray scattering (SAXS) experiments performed in real time, we show that freezing of aqueous solutions of copolymer amphiphilic molecules can induce self-assembly below 0 °C.

When using the bottom-up approach with anisotropic building-blocks, an important goal is to find simple methods to elaborate nanocomposite materials with a truly macroscopic anisotropy. Here, micrometer size colloidal mesoporous particles with a highly anisotropic rod-like shape (aspect ratio ≈ 10) have been fabricated from silica (SiO2 ) and iron...

In order to formulate stable foams with gels, it is important to know their shear rheology properties. We illustrate this fact using a weak gel made of a lyotropic lamellar phase (SDS/hexanol/brine system). The effect of shear is investigated using rheology experiments coupled with Small Angle X-ray Scattering (rheo-SAXS) using synchrotron radiatio...

An efficient method to form 3D superlattices of gold nanoparticles inside oil emulsion droplets is presented. We demonstrate that this method relies on Ostwald ripening, a well-known phenomenon occurring during the ageing of emulsions. The key point is that the nanoparticle concentration inside the smaller droplets is increasing very slowly with ti...

Nucleation and growth of SBA-15 silica nanostructured particles with well-defined morphologies has been followed with time by Small Angle X-ray Scattering (SAXS) and Ultra Small Angle X-ray Scattering (USAXS), using synchrotron radiation. Three different morphologies have been compared: platelets, toroids and rods. SEM observations of the particles...

The stability of foams made with sponge phases (L3 phases) and lamellar phases (Lα phases), both containing surfactant bilayers, has been investigated. The extreme stability of foams made with lamellar phases seems essentially due to the high viscosity of the foaming solution, which slows down gravity drainage. Moreover, the foams start draining on...

The formation of two-dimensional (2D)-hexagonal (p6m) silica-based hybrid material with a dual-mesoporosity is investigated in situ using synchrotron time-resolved Small Angle X-ray Scattering (SAXS). The material is synthesized from a mixed micellar solution of a nonionic fluorinated surfactant, RF₈(EO)₉, and a nonionic triblock copolymer, P123. B...

Ultrathin gold nanowires (NWs) dispersed in hexane were prepared by chemical reduction of HAuCl4 in oleylamine, along with nanospheres (NSs), side products of the reaction. X-ray photoelectron spectroscopy and small-angle X-ray scattering evidenced a stabilization of these nano-objects by oleylammonium chloride surfactants. The directed assembly of...

Interaction between hydrophobically-coated gold nanoparticles suspended in oil is usually described combining strong attractive van der Waals attraction between the gold cores and interaction between the ligands. This last interaction is expected to be purely repulsive if the suspending medium is a good solvent for the ligands or partially attracti...

Ultrathin Au nanowires were prepared following two routes: the reduction of the lamellar phase [OY−AuICl] in an excess of pure oleylamine and the direct reduction of AuIII in a solution of oleylamine in hexane. The superiority of the reduction of chloride gold precursor in isotropic environment is evidenced by small-angle X-ray scattering (SAXS) me...

We report the self-assembly of gold nanowires into hexagonal superlattices in liquid phase followed by in-situ Small Angle X Ray Scattering and give new insights on their growth mechanism. The unprecedented large interwire distance of 8 nm strongly suggests the stabilization of the ultrathin gold nanowires by a ligand's double layer composed of ole...

Clay minerals, like beidellite or nontronite, spontaneously exfoliate in water and form colloidal suspensions of nanosheets. In a given range of concentration, these suspensions display a nematic liquid–crystalline phase whose structure and properties can be conveniently studied in detail by polarized-light microscopy and small-angle X-ray scatteri...

The contact between two layers of double-chained C$_{18}$ surfactant adsorbed on silica has been investigated. Using a custom-made Surface Forces Apparatus with high stiffness, we have studied the process of 1) compression and collapse of the layers and 2) surface separation after layer collapse. A continuum mechanics model accounts for the compres...

The morphology control of the (sub) micrometer particles of mesoporous silica materials can be crucial in many applications. For particles of the SBA-15 material, the morphology happens to be easily tuned by simply changing the synthesis temperature, and well defined shapes are obtained, ranging from hexagonal columns, rice grains and rods to nano-...

Through the use of low voltage high resolution scanning electron microscopy (LV-HRSEM) we have studied the fine details of the intricate pore structure of SBA-15. Intrawall pores and deviations from the ideal and uniform cylindrical pores are clearly observed, and we report for the first time the direct observation of “plugs” in the pores. N2-sorpt...

We demonstrate a unique shear-induced crystallization phenomenon above the equilibrium freezing temperature $$\left({T}_{K}^{o}\right)$$ in weakly swollen isotropic $$\left({L}_{i}\right)$$ and lamellar $$\left({L}_{\alpha }\right)$$ mesophases with bilayers formed in a cationic-anionic mixed surfactant system. Synchrotron rheological X-ray diffrac...

The formation of 2D-hexagonal (p6m) silica-based hybrid materials from concentrated micellar solutions (10 wt%) of two nonionic fluorinated surfactants ( and ) is investigated in situ using synchrotron time-resolved Small Angle X-Ray Scattering (SAXS). The two surfactants form direct micelles with different structures prior to the silica precursor...

In this review, recent progress in the understanding of the formation of various silica mesoporous materials is reported. Owing to time-resolved experiments using Small Angle X-ray or Neutron Scattering (SAXS or SANS), it is possible to follow in situ the formation of a material during its synthesis via the Cooperative Templating Mechanism (CTM). S...

The mechanisms of formation of organically modified (phenyl, vinyl, and methyl) silica materials with cubic Pm3̅n and hexagonal p6m periodic mesostructures obtained in one step in the presence of the cetyltrimethylammonium bromide (CTA(+)B) surfactant are reported in this study. Understanding the way these complex materials form is difficult but un...

We study charged nanoparticles adsorbed onto surfactant bilayers using small-angle scattering of synchrotron radiation. The in-plane interaction of the particles is well described by a DLVO component (measured independently in solution) and a repulsive dipolar interaction due to the presence of the interface, with an amplitude close to the theoreti...

Three-dimensional periodic complex structures are encountered in various soft matter systems such as liquid crystals, block-copolymer phases and the related nano-structured materials. Here, we review several well-defined topologies: two-dimensional hexagonal phase, three-dimensional packing of spheres, tetrahedral close packing (tcp) bi-continuous...

Here we report the use of cubic and hexagonal phases of lyotropic liquid crystals as templates for the synthesis of zinc oxide nanoparticles. The templating effect of the lyotropic phases resulted in the formation of isotropic nanoparticles, whose size and assembly were dictated by the geometry of hydrophobic PPO cores and the nature of the phase.

Nematic and isotropic aqueous suspensions of beidellite clay sheets have been submitted to magnetic and a. c. electric fields. The nematic suspensions have positive anisotropy of magnetic susceptibility and negative anisotropy of electric susceptibility because the clay sheets orient their normals parallel to the magnetic field but perpendicular to...

Self-assembled organic-inorganic materials studied by synchrotron radiation Since the discovery of ordered mesoporous materials templated with amphiphilic molecules or macromolecules, their mechanism of formation raised many questions. Small angle X-ray scattering coupled with synchrotron radiation appeared rapidly as a unique technique to follow i...

A lamellar surfactant mesophase is used as a soft confinement medium for gold nanoparticles that are directly synthesized inside the lamellar mesophase by the radiolytic reduction of a gold salt incorporated into the water medium. By increasing the water layer thickness of the mesophase, spherical gold nanoparticles of increasing size are obtained....

The micellar state of Pluronic P123, which is a poly(ethylene oxide)-b-poly(propylene oxide)-b- poly(ethylene oxide) block polymer (EO(20)PO(70)EO(20)), has been investigated using SANS, SAXS, and differential scanning calorimetry under the conditions utilized in the synthesis of ordered mesoporous materials, such as SBA-15. The absolute intensity...

The different steps of the self-assembly in solution of several 2D-hexagonal silica nanostructured SBA-15 materials have been investigated by SAXS and SANS in situ experiments. Unique quantitative information about the shape and size evolution upon time of the micellar aggregates throughout the self-assembly process is obtained using a complete mod...

Hydrophobically coated gold nanoparticles have been inserted in swollen surfactant lamellar phases. Insertion of the gold nanoparticles is observed only above a critical hydrophobic thickness that depends on the particle size. Such a system can thus be used as a size filter for hydrophobically coated gold nanoparticles. Above this critical thicknes...

The morphological control of polymer micellar aggregates is a very important issue in applications such as drug delivery and material science. We report the temperature-controlled formation of nanotubes, nanofibers, ellipsoidal and faceted vesicles, and spherical aggregates by nanoprecipitation of amphiphilic diblock copolymers in dioxane/water mix...

Aqueous suspensions of swelling clay minerals exhibit a rich and complex rheological behaviour. In particular, these repulsive systems display strong shear-thinning at very low volume fractions in both the isotropic and gel states. In this paper, we investigate the evolution with shear of the orientational distribution of aqueous clay suspensions b...

We study the influence of nanoparticle doping on the lyotropic liquid crystalline phase of the industrial surfactant Brij®30 (C₁₂E₄) and water, doped with spherical polyoxometalate nanoparticles smaller than the characteristic dimensions of the host lamellar phase. We present viscometry and in situ rheology coupled with small-angle X-ray scattering...

We discuss the application of in-situ rheological small angle X-ray scattering experiments to the study of complex fluids under shear, implemented using custom Couette cylinder rheometers mounted on the SWING beamline of the SOLEIL Synchrotron. We discuss several applications of this technique to the study of phase transitions in nanoparticle doped...

We show in the present letter that the organization of colloidal suspensions of very anisometric repulsive particles can be understood on the basis of simple geometrical considerations. Using a large set of rod-like and plate-like particles, we first evidence that the experimental inter-particle distances can be accurately predicted from geometrica...

Using pulsed gradient spin-echo NMR, we studied molecular self-diffusion in aligned samples of a hybrid lyotropic lamellar L(alpha) phase. This composite organic-inorganic material was obtained by doping the lamellar phase of the nonionic surfactant Brij-30 with the [PW(12)O(40)](3-) polyoxometalate (POM). Both water and POM self-diffusion display...

After size-selection and osmotic pressure measurements at fixed ionic strength, the behavior of aqueous colloidal suspensions of anisotropic disklike beidellite clay particles has been investigated by combining optical observations under polarized light, rheological, and small angle X-ray scattering (SAXS) experiments. The obtained phase diagrams (...

Time-resolved in situ Small Angle Neutron Scattering (SANS) investigations have provided direct experimental evidence for the initial steps in the formation of the SBA-15 mesoporous material, prepared using the non-ionic tri-block copolymer Pluronic 123 and TEOS as silica precursor. Upon time, three steps take place during the cooperative self-asse...

We study by synchrotron small-angle x-ray scattering highly aligned lamellar phases of a zwitterionic surfactant, doped with monodisperse and spherical hydrophobic inorganic particles as a function of particle concentration. Analysis of the structure factor of the two-dimensional fluid formed by the particles in the plane of the bilayer gives acces...

This work presents an overview of the data obtained for SBA-15 synthesis under the reaction conditions using synchrotron based small angle X-ray scattering and small angle neutron scattering. Three major stages in the synthesis of SBA-15 materials proceeding according to the cooperative self-assembly mechanism have been identified, and the structur...

This work reports the elaboration and structural study of new hybrid organic-inorganic materials constructed via the coupling of liquid-crystalline nonionic surfactants and polyoxometalates (POMs). X-ray scattering and polarized light microscopy demonstrate that these hybrid materials, highly loaded with POMs (up to 18 wt %), are nanocomposites of...

Radiolytic reduction of mixed Au III /Fe II ethylene glycol solutions led to two kinds of particles: 2 nm Fe rich nanoparticles as well as large rods (a few tens of nm) and faceted particles rich in gold and containing a small amount of iron. The adjunction of iron to gold enhances remarkably its electro-catalytic properties toward oxygen and proto...

Thermal treatments before and after precipitation during the synthesis of SBA-15 materials were studied. It was found that thermal treatments in a range of 28–55 °C during the first 10 min of TEOS polymerization had an effect on surface silanol groups and the amount of microporosity in the final SBA-15 materials. FTIR analysis of these obtained SBA...

We have investigated dilute aqueous solutions of an anionic polymer (carboxymethylcellulose) mixed with cationic surfactants of different chain lengths (dodecyl to octadecyl trimethylammonium bromides: DTAB, TTAB, CTAB and OTAB). The structures of the concentrated phases formed above the precipitation threshold were studied by X-ray diffraction. Di...

https://tel.archives-ouvertes.fr/tel-01989825

The knowledge of the exact shapes of micelles in various micellar phases found in both lyotropic and thermotropic liquid crystals is very important to our understanding of the underlying principles of molecular self-assembly. In the current paper we present a detailed structural study of the hexagonal close packed (hcp, space group P63/mmc) micella...

We explore the use of using post-synthesis basic treatments under mild conditions (hot water or concentrated ammonia solutions for temperatures not exceeding 100 degrees C) in order to modify the porosity of SBA-15 silicas. Dissolution and restructuration processes occurring inside the silica walls induce a hierarchical porosity (micro, meso, macro...

Time-resolved in situ SANS investigations have provided direct experimental evidence for the three initial steps in the formation of the SBA-15 mesoporous material: an induction period is followed by a shape transformation of the micelles from spherical to cylindrical ones followed by the precipitation of a two-dimensional hexagonal phase.

Du fait du grand nombre d'atomes exposés sur leur surface et de propriétés redox particulières, des nanoparticules d'oxydes de métaux de transition pourraient avantageusement remplacer les métaux nobles pour la gestion de problèmes environnementaux (élimination de CO à basse température, procédés deNOx). Ces nanoparticules peuvent être obtenues par...

Single-crystalline platinum nanorods, monodisperse in diameter, are synthesized through a simple process at room temperature, in cetyltrimethyl ammonium bromide (CTAB) solution. The complexation of the CTA+ surfactant ion with tetrachloroplatinate in the presence of hexanol leads to the formation of a precipitate with a lamellar crystalline structu...

We obtained monocrystalline droplets in a thermotropic cubic phase, of approximate size 100 microm, deposited on a flat surface. The facets of these soft crystals are explored using both an optical microscope and an AFM. The height of individual steps on the principal facets and the lateral distance between steps in vicinal facets are measured usin...

The initial stages of SBA-15 synthesis have been studied by using in situ time-resolved small-angle X-ray scattering with a synchrotron radiation source. The quantitative analysis of X-ray scattering and diffraction intensities allows the structures of intermediates to be identified at the different stages of SBA-15 synthesis. Following tetraethylo...

Soft matter such as surfactant-water systems, block copolymers or liquid crystals can form periodic structures on nanometre to micrometre scales. This property can be used for templating nanoporous ceramics, surface patterning for electronic devices, or generation of photonic materials. Much attention has been paid to structures appearing between t...

AbstractThanks to important recent progress in the synthesis of mesomorphic molecules, thermotropic cubic phases have become more and more widespread. Many new examples of the Ia3¯d bicontinuous cubic phase have been discovered. Moreover, a multi-continuous Im3¯m cubic phase is up to now specific to thermotropic mesophases, and its exact structure...

Two series of hydrogen-bonded liquid-crystalline ferrocenes have been prepared by reacting ferrocene derivatives carrying a carboxylic acid function and two flexible alkyl chains (containing n = 8, 10, or 12 carbon atoms) with stilbazoles bearing a flexible alkyl chain (containing m = 6 or 10 carbon atoms). The first family of materials (m = 6; n =...

We have used 2D hexagonal SBA-15 silicas as templates for the nanofabrication of Mn oxide particles. Despite challenging aspects (several oxidation states of manganese, several polymorphs for each oxidation state), manganese oxides were chosen because of the high economical and environmental significance associated with their ion-exchange, molecula...

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