Graphene and its composites are of primary importance, particularly in the field of energy storage. Numerous bottom-up and top-down methods have been proposed in the literature to produce these materials with enhanced physicochemical properties. Recently, an innovative and green methodology was developed based on ionizing radiation, allowing the quantitative synthesis of graphene oxide-based materials. With the aim to extend this strategy for the preparation of hybrid nanomaterials, the objective of this work was the one-pot synthesis of nanocomposites composed of reduced graphene oxide - gold nanoparticles (rGO-AuNPs) via gamma ray-induced radiolytic reduction. UV-Vis Absorption Spectroscopy, Fourier Transform Infrared Spectroscopy, Raman Spectroscopy and X-ray Photoemission Spectroscopy were utilized to comprehensively evaluate the reduction degree of graphene oxide and the formation of gold nanoparticles. Atomic Force Microscopy and Scanning Electron Microscopy were employed to obtain the morphological and topographical information on synthesized nanocomposites. Thermal properties were investigated by Thermogravimetric Analysis and electrical properties were investigated using Cyclic Voltammetry and Potentiostatic Charge and Discharge method. The results demonstrated the successful reduction of graphene oxide and gold ions through the drastic transformation of oxygencontaining functional groups and the formation of gold nanoparticles. Electrical characterization results highlighted the excellent electrical properties of radiosynthesized rGO-AuNPs composites and their great potential for supercapacitance application.

We investigated the behavior of a pH-responsive polystyrene-b-poly(2-dimethylamino)ethyl methacrylate (PS-b-PDMAEMA) diblock copolymer at the air/water interface. We synthetized different copolymers with a small hydrophobic PS block of constant length attached to polyelectrolyte PDMAEMA blocks of various lengths. We demonstrate that a Langmuir monolayer is formed with the hydrophobic collapsed PS block anchoring the hydrophilic polyelectrolyte at the interface. By combining macroscopic surface pressure measurements and specular neutron reflectivity, we studied the monolayers as a function of surface density sigma and pH of the subphase. At pH = 2, the PDMAEMA is fully charged and the system at high s behaves as a polyelectrolyte brush with chains protruding in water with a gaussian profile. At pH = 10 where the PDMAEMA is neutral, the system exhibits a phase transition between the pancake configuration to the brush configuration, with a threshold that depends on the PDMAEMA chain length, in agreement with theoretical predicted scaling laws.

We show by X-ray and neutron small-angle scattering that gold nanoparticles with controlled sizes and morphologies can be obtained by the metallic reduction of AuCl4- ions trapped in 3D organic molds by X-ray radiolysis. The molds are spherical frozen micelles of polystyrene-b-poly(dimethylaminoethyl methacrylate) (PS-b-PDMAEMA) block copolymer in acidic aqueous solution with a PS spherical core surrounded by a corona of PDMAEMA chains in good solvent. The behavior of micelles is controlled by the [AuCl4-]/[DMAEMA] ratio RAuCl4-/DMAEMA. At low gold concentration, AuCl4- ions condense on the positively charged DMAEMA moieties without changing the behavior of the PDMAEMA chains. At intermediate gold concentration, the ions induce a progressive contraction of the corona's chains and dehydration of micelles. At large gold concentration, the corona becomes a fully dry phase loaded with gold ions, which induces micelle aggregation. Radiolysis of the solution by an intense X-ray beam produces different types of gold nanoparticles with respect to RAuCl4-/DMAEMA and irradiation time. At RAuCl4-/DMAEMA = 0.033, irradiation produces in the first step gold clusters in the micelle corona which in the second step merge to form nanoparticles of a similar size to that of the micelle. Conversely, at RAuCl4-/DMAEMA = 0.33, micelles do not operate as templates but only as nucleation zones and large nanoparticles grow outside the micelles.

In this study, we have characterized graphene oxide films formed at the air-water interface by X-ray reflectivity and grazing incidence X-ray diffraction using synchrotron sources. Surprisingly, the results of both measurements show that at non zero surface pressures, the film is organized as a bilayer of sheets interfaced between air and water with water molecule bridges. Such a spontaneous bilayer structure and its evolution with respect to the surface pressure has been observed for the first time. These results should allow precise control of the density of sheets deposited on the substrate when these films are transferred through the Langmuir Blodgett or Schaefer procedures. Indeed, graphene oxide keeps on attracting more and more attention, increasing the need for the production of well-controlled graphene oxide thin films due to its application in energy devices or in sensor domains.

The self-aggregation, surface properties and foamability of the catanionic surfactant mixture cetyltrimethylammonium bromide (CTAB)/sodium octyl sulfonate (SOSo) have been investigated to obtain insight on the relation between bulk nanostructures, surfactant packing, and foam stability and aging. Light microscopy, SANS, cryo-TEM, DLS, surface tension, rheometry and direct photography were used to characterize mixtures with varying CTAB molar fraction, xCTAB. In the bulk, self-assembly is richer in the excess CTAB region than in the excess SOSo one. Starting from neat CTAB micelles and on addition of anionic surfactant, there is a change from small ellipsoidal micelles (1 < xCTAB ≤ 0.80) to large rodlike micelles (0.65 ≤ xCTAB ≤ 0.55) and then to vesicles (0 < xCTAB ≤ 0.50), with coexistence regions in between; SOSo-rich mixtures are thus dominated by vesicles. High size polydispersity for the micelles and vesicles is an intrinsic feature of this system. Foam stability is concomitantly impacted by xCTAB. SOSo is a small mobile molecule and so it disrupts foam stability, irrespective of the presence of vesicles. Foams are thus only stable in the CTAB-rich regions, and SANS shows that the shape of micelles and vesicles is unchanged inside the foam. Foam drainage is thereby mostly controlled by the presence of the elongated micelles through the solution viscosity, whereas coarsening is influenced by dense surfactant packing at the gas-liquid interfaces.

Foams are multiscale materials that have an enormous number of uses. As the relevant structural length-scales span from a few nanometres up to millimetres a number of characterisation methods need to be combined to obtain the full material structure. In this review we explain how foams can be explored using Small Angle Neutron Scattering (SANS). We remind the reader of the basics of SANS and contrast variation before we describe the different types of experiments that have been carried out on foams emphasising the specific role of neutrons in learning about the systems. To date SANS has been used to measure different foam structural parameters, such as the film thickness and the bubble size. Several studies have also been carried out to elucidate the organisation of the stabilising objects in the bulk solution. Finally we show how SANS measurements can be used to measure foam composition. Some of the accessible information is unique to SANS experiments, but as the method is still not very widely used on foams the review is also aimed to act as an introduction on how to carry out such measurements on foams.

The use and role of colloids as stabilizers in water of internally self-assembled domains dispersed from lipid-based lyotropic liquid crystalline phases is investigated and discussed. We focus on the relation between stabilization and formation of a colloidal armor around the lyotropic phase drops. Two different geometries (spherelike or disk-like) of colloids with similar radius, chemical surface, and charge have been successfully used to stabilize the nanostructured droplets of different lyotropic liquid crystalline phases (from cubic phases to inverse micellar phases) [1-7]. In particular, this has been shown referred as (V) are vesicles. using small angle x-ray scattering that the high pH due to Laponite (disk-like colloids) induced as transition from cubic phase (Cubosomes) to hexagonal phase (Hexosomes) when using monoglyceride lipids forming the lyotropic liquid crystalline phases. However, not much is known about the local structural composition of the cubosomes (morphology, topology...) stabilized by Laponite. This is the aim of the present study in which Cubosomes made of food-grade monoglyceride mixtures (Myverol product) stabilized in water by the presence of Laponite nanocolloids (disk-like solid colloids) have been examined using cryogenic transmission electron microscopy (cryo-TEM). The different morphologies locally observed have been determined, and characterized by FFT as well as describing the cubosomes by minimal surfaces. The study has been performed for fresh samples and for samples during time in order to characterize the in-situ pH-induced transition. The results are discussed in the viewed of the exact chemical composition of the lipid products.

Objective: The main objective of this study was to describe the distribution of referrals offered to patients assessed in the "Post-Acute Stroke program'' of Bordeaux University Hospital (France). This program was developed in 2008 to organize the dispensation of care in rehabilitation units specialized in neurological diseases.Material and methods: This was a single-centre observational study. Between July 2008 and December 2012, data on the number of stroke patients hospitalized at the Bordeaux University Hospital and their post-acute referral were collected from the local hospital discharge database. Some of these patients were assessed by Physical Rehabilitation and Medicine physicians participating in the program. Proposed and actual referrals, time from admission to assessment and functional status were also collected.Results: Among 4189 stroke patients, 1465 (35%) survivors were assessed, of whom 932 (22.2%) were discharged to inpatient rehabilitation facilities. There were no patients discharged to this type of unit without an assessment. Among the 1465 patients who were assessed, 57.2% were referred to specialized rehabilitation units, 6.3% were discharged to non-specialized rehabilitation units and 26% returned home directly. The median total length of stay in acute units varied from 10 to 15 days depending on referral orientation.Conclusion: Patients that were assessed were more likely to be transferred to specialized rehabilitation units than to non-specialized rehabilitation units. The Post-Acute Stroke program has the particularity of combining private and public specialized rehabilitation units in a common collaborative referral system while retaining the control and flexibility of personalised referral for each patient in the light of local care availability. (C) 2016 Elsevier Masson SAS. All rights reserved.

The spatial distribution of charged spherical colloids when used as stabilizers of phytantriol-based emulsified microemulsions (EME, L2 symmetry group) is investigated. The coverage of the lipid-based mesophases by the colloids is monitored using small-angle neutron scattering (SANS) in contrast matching conditions and visualized using cryogenic transmission electron microscopy (cryo-TEM) imaging. The results demonstrate that, despite the stability of the emulsion droplets, very few colloids are ever found on the droplets. The stability of the EMEs is suggested to arise from the very slow ripening rates combined with punctual repulsion against coalescence from the isolated charged colloids on the bigger droplet surfaces. We show the possibility of creating a dense cover around the droplets by partially hydrophobizing the colloids by adsorbing a cationic surfactant on their surface. This opens up the possibilities for further modulation of the colloidal coverage in these systems. This is an interesting route for the design of new Colloid-ISAsome assemblies in which dense protective armors could be advantageous such as controlled delivery.

Ultrastable foams are made very simply by adding salt (NaCl or KCl) to sodium dodecyl sulfate. The addition of high concentrations of salt leads to the precipitation of the surfactant on the bubble surfaces and as crystals in the interstices between the bubbles. As a consequence, the ageing of the foams is stopped to make them stable indefinitely, or until they are heated above the melting temperature of the crystals. The use of KCl is shown to be much more effective than that of NaCl because potassium dodecyl sulfate has a higher melting temperature and faster rates of crystallization. The crystalline structures have been investigated inside the foam using small angle neutron scattering. The larger lattice spacing of the crystals formed with NaCl in comparison with KCl has been evidenced. These simple temperature stimulable foams could have many potential applications.

We show that, while the gelation of colloidal silica proceeds much faster in the presence of added KCl than NaCl, the final gels are very similar in structure and properties. We have studied the gelation process by visual inspection and by small angle X-ray scattering for a range of salt and silica particle concentrations. The characteristic times of the early aggregation process and the formation of a stress-bearing structure with both salts are shown to collapse onto master curves with single multiplicative constants, linked to the stability ratio of the colloidal suspensions. The influence of the salt type and concentration is confirmed to be mainly kinetic, as the static structure factors and viscoelastic moduli of the gels are shown to be equivalent at normalized times. While there is strong variation in the kinetics, the structure and properties of the gel at long-times are shown to be mainly controlled by the concentration of particles, and hardly influenced by the type or the concentration of salt. This suggests that the differences between gels generated by different salts are only transient in time.

The mechanisms of association between neutral xyloglucan chains extracted from tamarind seeds are explored. Mesoscale structures involving a few chains are evidenced and monitored by static light scattering and low‐shear viscosity experiments as a function of the xyloglucan concentration, obtained from increasing the dilution of an initial dispersion. The mechanism of association is addressed by means of multiangle dynamic light scattering. The associations exist whether the chains are in the dilute regime or in the semi‐dilute regime and are characteristic of weak interactions. Their progressive loosening by dilution is evidenced and their level depends only on the xyloglucan concentration. The associations are due to a mechanism inherent to the nature of the chains. image

We review the current understanding of the stabilization mechanisms of internally self-assembled domains dispersed in water. These hierarchical particles are potential carriers of active molecules. The use of solid nanoparticles as stabilizers is a novelty in the field. The properties and the possible gain that can be obtained by using such stabilizers as a part of a delivery system based on dispersed lyotropic liquid crystalline phases of lipids represent the core of the present contribution. Two different types of particles (spheres and disks) have been successfully used to stabilize such droplets. The specific lipid-particle interactions as well as the physical parameters (surface curvature and stiffness) play an important role in the stabilization mechanism. However, indirect effects such as a change of pH can have an impact on the droplet stability and the internal structure. Using small-angle neutron scattering (SANS) and cryo-TEM, it is possible to show the existence of a protective armor around the droplets. Such armor is formed with the disk-like particles, but the adsorption of spherical particles is much lower, and creation of armor is only possible through a hydrophobic modification of the sphere surface. The colloid-stabilized nanoemulsions are interesting as smart carriers due to the possibilities of hierarchical functionalization of both the internal phase and the stabilizing particles.

The stabilisation of emulsified microemulsions using different concentrations of colloidal disk-like particles (Laponite) is investigated. The resulting structures are characterised by cryo-TEM, small-angle and very small-angle neutron scattering methods. We show that the Laponite colloids are effectively attached onto the droplet interfaces, creating a protective layer around them, dense enough to be statistically observed by means of neutron scattering, although the mean coverage remains still rather low. The mean size of the internally organised droplets does not change with the colloidal concentration (up to 1 wt%), and a few free colloids are found in the continuous water solvent. However, the colloids are shown to be able to deform the soft interfaces of the microemulsion phase to create droplets that are not always spherical, but can have angled interfaces.

We explored the behavior and the characteristics of xyloglucan polysaccharide chains extracted from tamarind seeds in aqueous media. The initial solubilization is achieved by using a 0.01 M NaOH solution. The absence of compact aggregates in the solution and the average molecular mass of the individual chains were unambiguously demonstrated by size exclusion chromatography with multi-angle light scattering detection. The composition and the stability of the solution were quantitatively checked over weeks by using liquid state nuclear magnetic resonance with DMSO as internal standard. The conformational characteristics of the chains were measured using nondestructive small-angle neutron scattering (SANS). The unambiguous determination of the Flory exponent (ν = 0.588) by SANS enabled us to directly prove that xyloglucan chains in water behave like semiflexible worm-like chains with excluded volume statistics (good solvent), contrary to most of the neutral water-soluble polymer chains that rather exhibit Gaussian statistics (θ-solvent). In addition to the Flory exponent, the persistence length l(p) and the cross section of the chains were also determined by SANS with utmost precision, with values of 80 and of 7 Å, respectively, which provides a complete description of the conformational characteristics of XG chains at all relevant length scales.

We explored the structural effects induced by the addition of salt on lipid-based liquid crystalline drops stabilized in aqueous media by charged sphere-like colloids. This allows us to distinguish two different stabilization regimes. In one case, the internal liquid crystalline phase has the ability to reorganize upon the coalescence of the drops and in the other not. This in turn depends mainly on the contact angle and the internal phase viscosity.