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(174) Production(s) de ANGLARET E.
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Control charge transfer in poyelectrolyte solutions of single-wall carbon nanotubes
Auteur(s): Anglaret E.
(Séminaires)
Humboldt Universität, dpt of physics (Berlin, DE), 2012-10-09 |
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Orientation of single-wall carbon nanotubes in composites
Auteur(s): Anglaret E.
(Séminaires)
Frei Universität, dpt of physics (Berlin, DE), 2012-11-13 |
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Dispersion and alignment of individual Single Wall Carbon Nanotubes in a chromonic liquid crystal
Auteur(s): Ould-Moussa Nawell, Blanc C., Zamora-Ledezma C., Maugey Maryse, Poulin Philippe, Anglaret E., Nobili M.
Conference: Chemontubes (Arcachon, FR, 2012-04-01)
Ref HAL: hal-00807072_v1
Exporter : BibTex | endNote
Résumé: Single Wall Carbon Nanotubes (SWNTs) display remarkable anisotropic features (mechanical, optical and conductivity properties). Exploiting them at a macroscopic scale requires both a good dispersion of individual tubes and a control of their orientational order at a large scale. The use of a liquid crystal as a structured solvent for aligning the tubes is attractive and several studies have already examined the dispersion of SWNTs in thermotropic or lyotropic liquid crystals. In this work, we used Disodium Chromoglycate (DSCG), a chromonic liquid crystal (LCLC) to disperse a large SWNT concentration (more than 0.1 %) in an aqueous nematic phase. The doped nematics and their orientation were studied by polarized microscopy, polarized Raman and photoluminescence spectroscopies (from individual semiconducting SWNT only). A quantitative approach [1-3] allowed us to determine accurately the order parameter of the tubes, which was found to be in the range 0.9-1.
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Controlling the Crystalline Quality and the Purity of Single-walled Carbon Nanotubes Grown by Catalytic Chemical Vapor Deposition
Auteur(s): Navas H., Picher Matthieu, Arenal Raul, Quesnel Etienne, Anglaret E., Jourdain V.
(Document sans référence bibliographique) 2012-12-01Texte intégral en Openaccess :
Ref HAL: hal-00802071_v1
Exporter : BibTex | endNote
Résumé: It is frequently observed that as-grown single-walled carbon nanotubes (SWCNTs) contain defects. Controlling the defect density is a key issue for the control of nanotube properties. However, little is known about the influence of the growth conditions on the formation of nanotube defects. In addition, SWCNT samples frequently contain carbonaceous by-products which affect their ensemble properties. Raman spectroscopy is commonly used to characterize both features from the measurement of the defect-induced D band. However, the contribution of each carbonaceous species to the D band is usually not known making it difficult to separately extract the defect density and relative abundance of each. Here, we report on the correlated evolution of the D and G' bands of SWCNT samples with increasing growth temperature. In the general case, three to four Lorentzian components are required to fit them. Coupled with HRTEM characterization, the low frequency components of the D and G' can be attributed to the contribution of SWCNTs while high frequency components are associated with defective carbonaceous by-products. The nature of these defective by-products varies with the type of catalysts and with the growth conditions.
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Liquid Crystallinity and Dimensions of Surfactant-Stabilized Sheets of Reduced Graphene Oxide
Auteur(s): Zamora-Ledezma C., Puech Nicolas, Zakri Cécile, Grelet Eric, E. Moulton Simon, G. Wallace Gordon, Gambhir Sanjeev, Blanc C., Anglaret E., Poulin Philippe
(Article) Publié:
Journal Of Physical Chemistry Letters, vol. 3 p.pp. 2425-2430 (2012)
Ref HAL: hal-00737951_v1
DOI: 10.1021/jz3008479
WoS: 000308342500022
Exporter : BibTex | endNote
57 Citations
Résumé: Graphene oxide (GO) flakes dissolved in water can spontaneously form liquid crystals. Liquid crystallinity presents an opportunity to process graphene materials into macroscopic assemblies with long-range ordering, but most graphene electronic functionalities are lost in oxidation treatments. Reduction of GO allows recovering functionalities and makes reduced graphene oxide (RGO) of greater interest. Unfortunately, chemical reduction of GO generally results in the aggregation of the flakes, with no liquid crystallinity observed. We report in the present work liquid crystals made of RGO. The addition of surfactants in appropriate conditions is used to stabilize the RGO flakes against aggregation maintaining their ability to form water-based liquid crystals. Structural and thermodynamical studies allow the dimensions of the flakes to be deduced. It is found that the thickness and diameter of RGO flakes are close to that of neat GO flakes.
Commentaires: 6 pages
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Mechanical reinforcement of a high-performance aluminium alloy AA5083 with homogeneously dispersed multi-walled carbon nanotubes
Auteur(s): Stein J., Lenczowski Blanka, Fréty Nicole, Anglaret E.
(Article) Publié:
Carbon, vol. 50 p.2264-2272 (2012)
Texte intégral en Openaccess :
Ref HAL: hal-00734896_v1
DOI: 10.1016/j.carbon.2012.01.044
WoS: 000302050200024
Exporter : BibTex | endNote
89 Citations
Résumé: Dense and homogeneous multi-walled carbon nanotube/metal composites are prepared by powder metallurgy. The distribution of the nano-reinforcements in the matrix is studied by scanning electron microscopy and Raman spectroscopy. The mechanical properties of the composites are determined by means of static tensile tests and Vickers micro-hardness measurements. We show that a homogeneous dispersion of the nanotubes at the micron scale is required in order to improve the mechanical properties of the metal matrix composite. This can be achieved using ball-milling through the mechanisms of plastic deformation and cold-welding. Accordingly, we report significant improvements to the mechanical properties of composites prepared with a high-performance aluminium alloy AA5083 matrix.
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Controlled alignment of individual single-wall carbon nanotubes at high concentrations in polymer matrices
Auteur(s): Zamora-Ledezma C., Blanc C., Anglaret E.
(Article) Publié:
The Journal Of Physical Chemistry C, vol. 116 p.13760 (2012)
Ref HAL: hal-00713317_v1
DOI: 10.1021/jp212113b
WoS: 000305769900036
Exporter : BibTex | endNote
16 Citations
Résumé: We show that single-wall carbon nanotubes (SWCNT) can be dispersed as individuals in poly(vinyl alcohol) matrix composites up to concentrations of 1 wt %, as indicated by their strong photoluminescence (PL) signal in the near-infrared all along the processing steps. The alignment of the SWCNT is controlled by hot-stretching of the composite films. We show that orientational order can be described accurately from polarized Raman and PL spectroscopies, in good agreement with a simple affine model, providing their anisotropic absorption is properly taken into account. Similar results are obtained from different excitation laser lines (in the visible and near-infrared), confirming that all nanotubes orient the same way.
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