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An anti-​corrosion soln. that is free of chromium in any oxidn. state, comprises at least one chem. oxidizing compd., at least one aluminum complexing agent, at least one corrosion inhibiting compd., and optionally, a chem. sealant compd., the soln. having a pH of 1-​5. A method for treating a metal surface comprises the application, on the surface, of the anticorrosion soln. in order to form a coating of a metal surface.

International audience

International audience

International audience

International audience; A hierarchically structured platform was obtained from spontaneous self-assembly of a poly(styrene)-b-poly(vinylbenzylchloride) (PS-b-PVBC) block copolymer (BCP) during breath figure (BF) templating. The BF process using a water/ethanol atmosphere gave a unique double porosity in which hexagonally arranged micron-sized pores were encircled by a secondary population of smaller, nano-sized pores. A third level of structuration was simultaneously introduced between the pores by directed BCP self-assembly to form out-of-the-plane nano-cylinders, offering very rapid bottom-up access to a film with unprecedented triple structure which could be used as a reactive platform for introducing further surface functionality. The surface nano-domains of VBC were exploited as reactive nano-patterns for site-specific chemical functionalization by firstly substituting the exposed chlorine moiety with azide, then “clicking” an alkyne by copper (I) catalyzed azide-alkyne Huisgen cycloaddition (CuAAC). Successful chemical modification was verified by NMR spectroscopy, FTIR spectroscopy, and XPS, with retention of the micro- and nanostructuration confirmed by SEM and AFM respectively. Protonation of the cyclotriazole surface groups triggered a switch in macroscopic behavior from a Cassie-Baxter state to a Wenzel state, highlighting the possibility of producing responsive surfaces with hierarchical structure.

Les matériaux composites utilisant des charges à base de nanotubes de carbone (CNTs) pourraient être une solution d’avenir pour l’allègement du packaging de l’électronique embarquée dans les avions. Les propriétés électriques et thermiques de ces matériaux peuvent être améliorées par le dépôt de métaux tels que le cuivre (Cu) à la surface des CNTs. Une voie possible est le dépôt chimique à partir d’une phase vapeur (CVD) en lit fluidisé, un procédé déjà maîtrisé à l’échelle industrielle. Cette communication présente des résultats de dépôts de nanoparticules de cuivre à la surface de CNTs multi-parois (MWCNTs) Graphistrength®C100 (Arkema), enchevêtrés sous forme de pelotes de 388 μm de diamètre médian. Le procédé de CVD en lit fluidisé (FBCVD) a été utilisé à pression atmosphérique, à partir de la sublimation d’acétylacétonate de cuivre (II) [Cu(acac)2]. Des expériences ont été menées sur CNTs bruts et sur CNTs pré-oxydés en lit fluidisé par un mélange gazeux H2O-O2-O3. Les Cu-MWCNTs obtenus ont été caractérisés par analyse thermo-gravimétrique (TGA), microscopie électronique à balayage associée à un canon à émission de champ et à un spectromètre à énergie dispersive X (FEG-SEM-EDX), diffraction des rayons X (XRD) et microscopie électronique à transmission (MET).

Les nanotubes de carbone (CNTs) présentent des propriétés physiques remarquables, mais l’inertie chimique de leur surface limite certaines de leurs applications, en particulier quand il est nécessaire soit de leur greffer de nouvelles fonctions, soit de les disperser dans des matrices polymères. Il faut donc augmenter leur réactivité chimique par la création de défauts de structures et/ou la fonctionnalisation de leur surface par des groupements oxygénés. De nombreuses équipes scientifiques ont déjà réussi à rendre les CNTs plus réactifs, mais en petites quantités (< 1 g) et généralement par voie liquide. Cette communication présente des résultats d’oxydation sur 100 g (par expérience) de CNTs multi-parois (MWCNTs) Graphistrength®C100 (Arkema). Différents mélanges gazeux oxydants ont été testés à base d’oxygène (O2), d’ozone (O3) et de vapeur d’eau (H2O) via le procédé de fluidisation à pression atmosphérique et température ambiante. Les O-MWCNTs obtenus ont été caractérisés par analyse thermo-gravimétrique (TGA), microscopie électronique à transmission (MET), spectrométrie photoélectronique X (XPS), spectroscopie infrarouge (MIR) et spectroscopie Raman.

International audience; In order to reduce formaldehyde emissions from wood panels resulting from their incorporation as adhesives, new, environmentally sustainable tannin-based adhesives were developed. The tannin was extd. from the bark of the maritime pine (Pinus pinaster). Exts. were characterized by 13C NMR spectroscopy., IR attenuated total reflectance-Fourier transform IR anal. (ATR-FTIR), XPS, Asym. Flow Field-Flow Fractionation (AF4), at. force microscopy (AFM), rheol. anal. and gas chromatog. (GC) to clarify its colloidal structure, functionality and rheol. behavior for adhesive applications.

International audience; Through a topochemical oxidative reaction (TOR) under air, a β-Co(OH)2 brucite type structure is converted into a monometallic CoIICoIII–CO3 layered double hydroxide (LDH). The structural and morphological characterizations are performed using powder X-ray diffraction, Fourier-transformed IR spectroscopy, and scanning and transmission electron microscopy. The local structure is scrutinized using an extended X-ray absorption fine structure, X-ray absorption near-edge structure, and pair distribution function analysis. The chemical composition of pristine material and its derivatives (electrochemically treated) are identified by thermogravimetry analysis for the bulk and X-ray photoelectron spectroscopy for the surface. The electrochemical behavior is investigated on deposited thin films in aqueous electrolyte (KOH) by cyclic voltammetry and electrochemical impedance spectroscopy, and their capacitive properties are further investigated by Galvanostatic cycling with potential limitation. The charge capacity is found to be as high as 1490 F g−1 for CoIICoIII–CO3 LDH at a current density of 0.5 A g−1. The performances of these materials are described using Ragone plots, which finally allow us to propose them as promising supercapacitor materials. A surface-to-bulk comparison using the above characterization techniques gives insight into the cyclability and reversibility limits of this material.

International audience; In the context of high demand for energy in mobile devices, many studies deal with the lithium-ion cell technology. Because of its larger uptake ability of Li, silicon was suggested for being used (combined with a conductive material) instead of graphite, currently the most frequently used anode material for combining good electrical conductivity and the ability to host Li as intercalated ions between the graphenes [1,2]. However, charge/discharge cycles induce fatal structural damages to bulk Si, as a consequence of successive swellings then shrinkings of the Si lattice [3]. Hence bulk graphite and/or Si anode materials could be replaced by nanostructured composites combining mechanical strength, electrical conductivity, and high charge capacity. Carbon nanotubes mixed with silicon nanoparticles appear as a promising material [4-6]. Here, multi-walled carbon nanotubes Graphistrength® were used as substrate for the Fluidized Bed Chemical Vapour Deposition (FBCVD) of silicon from silane (SiH4). The paper describes the synthesis and characterisation of the nanostructured composite material obtained, as well as the results of the electrochemical tests (involving chargedischarge cycles) carried-out to analyze their behavior as Li-ion cell anodes.