Development of furan-2,5-dicarboxylic acid (FDCA)-based organogelators.

Organogels are used in a wide range of applications for which the development of new bio-based organogelators is highly desirable. While furan-2,5-dicarboxylic acid (FDCA) is a promising molecule for the synthesis of bio-based polyesters, it has never been used in the context of organogels. This study explores the possibility to design FDCA-based organogelators that self-assemble into fibrillar networks stabilized by hydrogen bonding.

Crosslinked Elastomers: Structure-Property Relationships and Stress-Optical Law.

We present a combination of independent techniques in order to characterize crosslinked elastomers. We combine well-established macroscopic methods, such as rheological and mechanical experiments and equilibrium swelling measurements, a more advanced technique such as proton multiple-quantum NMR, and a new method to measure stress-induced segmental orientation by in situ tensile X-ray scattering. All of these techniques give access to the response of the elastomer network in relation to the crosslinking of the systems.

Following in Situ the Degradation of Mesoporous Silica in Biorelevant Conditions: At Last, a Good Comprehension of the Structure Influence.

Mesoporous silica nanoparticles (MSNs) have seen a fast development as drug delivery carriers thanks to their tunable porosity and high loading capacity. The employ of MSNs in biomedical applications requires a good understanding of their degradation behavior both to control drug release and to assess possible toxicity issues on human health. In this work, we study mesoporous silica degradation in biologically relevant conditions through in situ ellipsometry on model mesoporous nanoparticle or continuous thin films, in buffer solution and in media containing proteins.

Organogel Formation Rationalized by Hansen Solubility Parameters: Shift of the Gelation Sphere with the Gelator Structure.

To rationalize how the gelation ability of a low molecular weight gelator is influenced by its molecular structure, we performed extensive solubility tests of a group of thiazole-based gelators and made use of Hansen solubility parameter formalism. We observe that the increase of a linear alkyl chain in these gelators promotes an increase of the radius of the gelation sphere as well as a gradual shift of its center to lower values of the polar (δ) and hydrogen bonding (δ) components. The molecular packing within the fibers and the crystal habit were determined by a combination of X-ray diffraction and molecular modeling.

AIE Fluorescent Gelators with Thermo-, Mechano-, and Vapochromic Properties.

A series of aggregation-induced emission (AIE) fluorescent gelators (TPE-C -Chol) were synthesized by attaching tetraphenylethylene (TPE) to cholesterol through an alkyl chain. The properties of the gel, nano-/microaggregate, and condensed phases were studied carefully. TPE-C -Chol molecules form AIE fluorescent gels in acetone and in DMF.

Organogel formation rationalized by Hansen solubility parameters: improved methodology.

An organogel is obtained when a low molar mass compound forms a network of anisotropic fibres in a liquid that is therefore transformed into a macroscopic solid. Various approaches have been proposed to correlate organogel formation and Hansen solubility parameters. These approaches are well adapted to specific experimental datasets but lack universality.

Direct Evidence of Lithium Ion Migration in Resistive Switching of Lithium Cobalt Oxide Nanobatteries.

Lithium cobalt oxide nanobatteries offer exciting prospects in the field of nonvolatile memories and neuromorphic circuits. However, the precise underlying resistive switching (RS) mechanism remains a matter of debate in two-terminal cells. Herein, intriguing results, obtained by secondary ion mass spectroscopy (SIMS) 3D imaging, clearly demonstrate that the RS mechanism corresponds to lithium migration toward the outside of the Li CoO layer.

Dispersion of Hydrophobic Co Supracrystal in Aqueous Solution.

Assembly of nanoparticles into supracrystals provides a class of materials with interesting optical and magnetic properties. However, supracrystals are mostly obtained from hydrophobic particles and therefore cannot be manipulated in aqueous systems, limiting their range of applications. Here, we show that hydrophobic-shaped supracrystals self-assembled from 8.

Binary Superlattices from {Mo132} Polyoxometalates and Maghemite Nanocrystals: Long-Range Ordering and Fine-Tuning of Dipole Interactions.

In the present article, the successful coassembly of spherical 6.2 nm maghemite (γ-Fe2O3) nanocrystals and giant polyoxometalates (POMs) such as 2.9 nm {Mo132} is demonstrated.

Spontaneous formation of high-index planes in gold single domain nanocrystal superlattices.

Crystals of nanocrystals, also called supracrystals and nanocrystal superlattices, are expected to exhibit specific properties that differ from both the corresponding bulk material and nanosized elementary units. In particular, their surfaces have a great potential as nanoscale interaction plateforms. However, control of the symmetry, compacity, and roughness of their surfaces remains an open question.

Engineering functionality gradients by dip coating process in acceleration mode.

In this work, unique functional devices exhibiting controlled gradients of properties are fabricated by dip-coating process in acceleration mode. Through this new approach, thin films with "on-demand" thickness graded profiles at the submillimeter scale are prepared in an easy and versatile way, compatible for large-scale production. The technique is adapted to several relevant materials, including sol-gel dense and mesoporous metal oxides, block copolymers, metal-organic framework colloids, and commercial photoresists.

Hierarchy in Au nanocrystal ordering in a supracrystal: II. Control of interparticle distances.

Au nanocrystals coated with thiol derivatives differing by the length of their alkyl chains are used to build 3D superlattices called supracrystals. In this study, we used two sets of Au nanocrystals differing by their sizes and size distributions. The average sizes are 5 nm (Au5) and 7 nm (Au7).

X-ray scattering determination of the structure of water during carbon nanotube filling.

We present in situ monitoring of water filling of single-walled carbon nanotubes at room temperature, using X-ray scattering. A systematic method is developed to determine the water radial density profile. Water filling is homogeneous below about 5% in mass, whereas it structures into three layers above.

Simultaneous interfacial and precipitated supracrystals of Au nanocrystals: experiments and simulations.

Under solvent saturation, a precipitation of full-grown supracrystals on the one hand and the formation of well-defined supracrystalline films at the air-liquid interface on the other hand were previously observed for the first time (J. Am. Chem.

Crystallinity segregation upon selective self-assembling of gold colloidal single nanocrystals.

Spontaneous separation of single from polycrystalline 5 nm gold nanocrystals (NCs) is observed in colloidal solution. This segregation takes place upon self-assembling of single crystalline NCs at the air-solvent interface and in precipitated superlattices. Polycrystalline NCs are observed to remain in the suspension.

Self-assembly of amphiphilic liquid crystal polymers obtained from a cyclopropane-1,1-dicarboxylate bearing a cholesteryl mesogen.

We study the self-assembly of a new family of amphiphilic liquid crystal (LC) copolymers synthesized by the anionic ring-opening polymerization of a new cholesterol-based LC monomer, 4-(cholesteryl)butyl ethyl cyclopropane-1,1-dicarboxylate. Using the t-BuP(4) phosphazene base and thiophenol or a poly(ethylene glycol) (PEG) functionalized with thiol group to generate in situ the initiator during the polymerization, LC homopolymer and amphiphilic copolymers with narrow molecular weight distributions were obtained. The self-assemblies of the LC monomer, homopolymer, and block copolymers in bulk and in solution were studied by small-angle X-ray scattering (SAXS), differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and transmission electron microscopy (TEM).

Elaboration of Prussian Blue Analogue/Silica Nanocomposites: Towards Tailor-Made Nano-Scale Electronic Devices.

The research of new molecular materials able to replace classical solid materials in electronics has attracted growing attention over the past decade. Among these compounds photoswitchable Prussian blue analogues (PBA) are particularly interesting for the elaboration of new optical memories. However these coordination polymers are generally synthesised as insoluble powders that cannot be integrated into a real device.

Simultaneous growths of gold colloidal crystals.

Natural systems give the route to design periodic arrangements with mesoscopic architecture using individual nanocrystals as building blocks forming colloidal crystals or supracrystals. The collective properties of such supracrystals are one of the main driving forces in materials research for the 21st century with potential applications in electronics or biomedical environments. Here we describe two simultaneous supracrystal growth processes from gold nanocrystal suspension, taking place in solution and at the air-liquid interface.

Sequential growth in solution of NiFe Prussian blue coordination network nanolayers on Si(100) surfaces.

Controlling the elaboration of Coordination Networks (CoNet) on surfaces at the nanoscale remains a challenge. One suitable technique is the Sequential Growth in Solution (SGS), which has the advantage to be simple, cheap and fast. We addressed two issues in this article: i) the controlled synthesis of ultra thin films of CoNet (thickness lower than 10 nm), and ii) the investigation of the influence of the precursors' concentration on the growth process.

High Zn content of Randall's plaque: a μ-X-ray fluorescence investigation.

Kidney stone disease, or nephrolithiasis, is a common ailment. Among the different risk factors usually associated with nephrolithiasis are dehydration, metabolic defects (especially with regard to calcium and oxalate). The presence of a mineral deposit at the surface of the renal papilla (termed Randall's plaque) has all been recently underlined.

Self-assembly of liquid crystal block copolymer PEG-b-smectic polymer in pure state and in dilute aqueous solution.

A series of amphiphilic LC block copolymers, in which the hydrophobic block is a smectic polymer poly(4-methoxyphenyl 4-(6-acryloyloxy-hexyloxy)-benzoate) (PA6esterl) and the hydrophilic block is polyethyleneglycol (PEG), were synthesized and characterized. The self-assembly of one of them in both the pure state and the dilute aqueous solution was investigated in detail. Nano-structures in the pure state were studied by SAXS and WAXS on samples aligned by a magnetic field.

X-ray diffraction study of the structure of carboxymethylcellulose-cationic surfactant complexes.

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. Different body-centred cubic structures with space groups Pm3n were observed in the presence of surfactant with a short aliphatic chain (DTAB), despite the fact that the polymer persistence length is comparable to the repeat distance of the structure (5 nm).

Formation of polymer vesicles by liquid crystal amphiphilic block copolymers.

We report the formation of polymer vesicles (or polymersomes) by a new class of amphiphilic block copolymers in which the hydrophobic block is a side-on nematic liquid crystal polymer. Two series of these block copolymers, named PEG-b-PA444 and PEG-b-PMAazo444, with different hydrophilic/hydrophobic ratios were synthesized and characterized in detail. Polymersomes and nanotubes were formed by adding water into a solution of copolymers in dioxane.

A new approach to grafting a monolayer of oriented Mn12 nanomagnets on silicon.

The functionalisation of a Si(100) silicon wafer allows for the oriented grafting of a monolayer of Mn12 nanomagnets using a two-step procedure.

Phase transformation during cubic mesostructured silica film formation.

The structural evolution taking place during CTAB/TEOS based solvent evaporation-induced thin film formation has been followed by in-situ time-resolved SAXS; this shows that the final Pm3n cubic structure is formed via the formation of lamellar and hexagonal intermediate structures within the water rich evaporation regime.