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International audience; The grafting of molecular monolayers is critical for the functionalization of surfaces. In molecular electrochemistry, the surface modification of electrodes and the way molecules are attached to the electrode surface are highly critical to electron transfers and electrochemical reactions. In this paper, sub-monolayers were covalently grafted onto glassy carbon (GC) electrodes via Diels−Alder cycloaddition with two soluble dienophiles, that is, propargyl bromide and ethynyl ferrocene. Such an approach is clean (no by-product, no catalyst/additive) and occurs under mild conditions by heating at 50°C in toluene for few hours. The as-modified electrodes were thoroughly characterized by FTIR, XPS, and cyclic voltammetry using both millimetric GC electrodes and ultra-microelectrodes. Cyclic voltammetry gave access to surface coverage and clearly evidenced the covalent grafting of sub-monolayers. The grafting of functional sub-monolayers via Diels− Alder cycloaddition could be easily extended to various functionalities and carbons to prepare electrochemical sensors or electrocatalytic surfaces.

International audience; Advanced reconstruction techniques allow to jointly estimate R2* and QSM in the brain from multi gradient-recalled echo sequences. This work aims at comparing several protocols in terms of coil setup and acceleration factors using available product sequences and modern hardware. In addition, an automatic and standardized post-processing pipeline is proposed for clinical studies. We show that quantitative values do not differ in terms of head coil, repetition time and acceleration factor used, thus allowing for a millimetric whole-brain coverage within 5 minutes scan time.

A mild and simple way to prepare stable aqueous colloidal suspensions of composite particles made of a cellulosic material (Sigmacell cellulose) and multiwalled carbon nanotubes (MWCNTs) is reported. These suspensions can be dried and redispersed in water at pH 10.5. Starting with rather crude initial materials, commercial Sigmacell cellulose and MWCNTs, a significant fraction of composite dispersed in water could be obtained. The solid composites and their colloidal suspensions were characterized by electronic microscopy, thermal analyses, FTIR and Raman spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and light scattering. The composite particles consist of tenuous aggregates of CNTs and cellulose, several hundred nanometers large, and are composed of 55 wt % cellulose and 45 wt % CNTs. Such particles were shown to stabilize cyclohexane-in-water emulsions. The adsorption and the elasticity of the layer they form at interface were characterized by the pendant drop method. The stability of the oil-in-water emulsions was attributed to the formation of an elastic network of composite particles at interface. Cyclohexane droplet diameters could be tuned from 20 to 100 μm by adjusting the concentration of composite particles. This behavior was attributed to the limited coalescence phenomenon, just as expected for Pickering emulsions. Interestingly, cyclohexane droplets were stable over time and sustained pH modifications over a wide range, although acidic pH induced accelerated creaming. This study points out the possibility of combining crude cellulose and MWCNTs through a simple process to obtain colloidal systems of interest for the design of functional conductive materials.

Commercial carboxymethylcellulose was used to prepare dispersible multi-walled carbon nanotubes-based composites. These composites were employed to prepare Pickering oil-in-water emulsions. Emulsion-templated macroporous materials were then prepared by embedding the oil droplets into a polymer resin arising from the polycondensation of furfural and phloroglucinol within the continuous aqueous phase in the presence of FeCl3 as catalyst. Polymerization afforded organic–inorganic nanocomposite materials in the form of capsules. After pyrolysis, highly microporous, magnetic and electrically conductive micrometric capsules could be obtained. This approach opens interesting prospects for catalysis, separation and electrochemistry applications.

The direct sol–gel encapsulation of an ionic liquid comprising a long alkyl chain imidazolium cation (1-methyl-3-octyl-imidazolium) and ibuprofenate anion, an active pharmaceutical ingredient, has been investigated. Silica ionogels either in the form of centimeter sized monoliths or nanometer sized particles were obtained depending on the conditions used. In both cases, the ionic liquid acted as a templating agent and a catalyst, promoting its own encapsulation. Monolithic ionogels were prepared by a simple hydrolytic method using tetramethoxysilane as the silica source. High pore volumes were measured after removal of the ionic liquid, in relation with the bulkiness of the ions. Typically, surface areas and pore volumes as high as 812 m2 g−1 and 1.25 cm3 g−1 were obtained using a low ionic liquid to silica ratio equal to 0.25, but still representing a high Ibuprofen loading equal to 46 wt%. At the same time, the ibuprofenate anion acted as a catalyst for the sol–gel reaction and a relatively high condensation degree was obtained (88%). Moreover, it was possible to benefit from the fact that the ionic liquid self-organized into micelles in aqueous solutions to incorporate it into mesoporous silica nanospheres in the absence of any organic solvent or other additives using tetraethoxysilane as the silica source. The mechanism involved was evidenced by transmission electron microscopy (TEM). Spherical silicate micelles of 30–40 nm were first formed, followed by their aggregation into spherical nanoparticles. Effects of time, temperature, and ionic liquid concentration on the formation of these silica nanospheres were also investigated.