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Matière Molle
(421) Articles dans des revues
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SANS study of the self-organization of gradient copolymers with ligand groups in supercritical CO2
Auteur(s): Ribaut Tiphaine, Oberdisse J., Annighofer Burkhard, Stoychev Ivan, Fournel Bruno, Sarrade Stéphane, Lacroix-Desmazes Patrick
(Article) Publié:
Soft Matter, vol. 5 p.4962-4970 (2009)
Texte intégral en Openaccess :
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Dynamics of a colloid-stabilized cream
Auteur(s): Herzig E. M., Robert A., Zand D. D. van 't, Cipelletti L., Pusey P. N., Clegg P. S.
(Article) Publié:
Physical Review E: Statistical, Nonlinear, And Soft Matter Physics, vol. 79 p.011405 (2009)
Texte intégral en Openaccess :
Ref HAL: hal-00512105_v1
PMID 19257033
Ref Arxiv: 0812.3847
DOI: 10.1103/PhysRevE.79.011405
WoS: 000262976600046
Ref. & Cit.: NASA ADS
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22 Citations
Résumé: We use x-ray photon correlation spectroscopy to investigate the dynamics of a high volume fraction emulsion creaming under gravity. The dodecane-in-water emulsion has interfaces stabilized solely by colloidal particles (silica). The samples were observed soon after mixing: as the emulsion becomes compact we discern two regimes of ageing with a cross-over between them. The young emulsion has faster dynamics associated with creaming in a crowded environment accompanied by local rearrangements. The dynamics slow down for the older emulsion although our studies show that motion is associated with large intermittent events. The relaxation rate, as seen from the intensity autocorrelation function, depends linearly on the wave vector at all times; however, the exponent associated with the line shape changes from 1.5 for young samples to less than 1 as the emulsion ages. The combination of ballisticlike dynamics, an exponent that drops below 1 and large intermittent fluctuations has not been reported before.
Commentaires: 8 pages, 5 figures
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Anisotropic Thin Films of Single-Wall Carbon Nanotubes from Aligned Lyotropic Nematic Suspensions
Auteur(s): Zamora-Ledezma C., Blanc C., Maugey M., Zakri C., Poulin P., Anglaret E.
(Article) Publié:
Nano Letters, vol. 8 p.4103-4107 (2008)
Ref HAL: hal-00504366_v1
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Résumé: Lyotropic nematic aqueous suspensions of single-wall carbon nanotubes can be uniformly aligned in thin cells by shearing. Homogeneous anisotropic thin films of nanotubes can be prepared by drying the nematic. Optical transmission between parallel or crossed polarizers is measured and described in order to estimate the dichroic ratio. The order parameter is measured using polarized Raman spectroscopy and found to be quite weak due to entanglement of the nanotubes and/or to an intrinsic viscoelastic behavior of the nanotube suspensions.
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Tuning colloidal interactions through coordination chemistry
Auteur(s): Joubert M., In M.
(Article) Publié:
Chemphyschem, vol. 9 p.1010-1019 (2008)
Texte intégral en Openaccess :
Ref HAL: hal-00534477_v1
PMID 18418820
DOI: 10.1002/cphc.200700593
WoS: 000255845500009
Exporter : BibTex | endNote
4 Citations
Résumé: The present work addresses the question of the range and amplitude of bridging attraction that is induced between surfactant micelles functionalized with complexing groups in the presence of coordination centers. An alkylethoxylated ester phosphate (AEP) is synthesized from a non-ionic surfactant and anchored into DTAB micelles. In the absence of any coordination center, functionalized micelles repel each other. Phase behavior, dynamic light scattering and small angle neutrons scattering (SANS) experiments show that this repulsive interaction is switched to attractive by the addition of coordination centers such as aluminum cations. The extent of the composition range of coexisting phase depends on the concentration of coordination center and on the pH. Analysis of the structure factor obtained from SANS shows that the range of attraction is determined by the molecular dimension of the chelating surfactant, while the depth can be tuned with the concentration of coordination center and the pH, The strong influence of the pH is interpreted as arising from the condensation of aluminium cations that lead to high functional polynuclear complexes.
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Elasticity of two-dimensional crystalline monolayers of fatty acid salts at an air-water surface
Auteur(s): Daillant Jean, Pignat Jeremy, Cantin Sophie, Perrot Francoise, Mora S., Konovalov Oleg
(Article) Publié:
Soft Matter, vol. 5 p.203-207 (2009)
DOI: 10.1039/b810134e
WoS: 000263272100025
10 Citations
Résumé: The elastic properties of organic-inorganic two-dimensional crystals floating at the water surface have been fully characterized by grazing incidence X-ray diffuse scattering and high-resolution diffraction. We show that the strong interaction between the organic molecules and the inorganic divalent cations is enough for these nm thick crystals to behave like true solids, with a residual tension of 1 x 10(-4)-10(-3) N m(-1). Their bending rigidity is renormalized as kappa(q) proportional to q(-eta k) with eta(k) = 0.25 +/- 0.07 and a microscopic value approximate to 100 k(B)T at q = 1 x 10(9) m(-1). The in-plane elastic constants behave like q(eta u) with eta(u) = 1.41 +/- 0.2, obeying the scaling relation eta(u) = 2 - 2 eta(k). These results are consistent with a long-range phonon-mediated interaction between out-of-plane fluctuations but the values of the exponents differ from those generally obtained in numerical simulations.
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Cellular-scale hydrodynamics
Auteur(s): Abkarian M., Faivre Magalie, Horton Renita, Smistrup Kristian, Best-Popescu Catherine, Stone Howard
(Article) Publié:
Biomedical Materials, vol. 3 p. (2008)
Texte intégral en Openaccess :
Ref HAL: hal-01870702_v1
PMID 18765900
DOI: 10.1088/1748-6041/3/3/034011
WoS: 000258916500013
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139 Citations
Résumé: Continuous and simultaneous measurement of the tank-treading motion of red blood cells and the surrounding flow using translational confocal micro-particle image velocimetry (micro-PIV) with sub-micron resolution M Oishi, K Utsubo, H Kinoshita et al. Abstract Microfluidic tools are providing many new insights into the chemical, physical and physicochemical responses of cells. Both suspension-level and single-cell measurements have been studied. We review our studies of these kinds of problems for red blood cells with particular focus on the shapes of individual cells in confined geometries, the development and use of a 'differential manometer' for evaluating the mechanical response of individual cells or other objects flowing in confined geometries, and the cross-streamline drift of cells that pass through a constriction. In particular, we show how fluid mechanical effects on suspended cells can be studied systematically in small devices, and how these features can be exploited to develop methods for characterizing physicochemical responses and possibly for the diagnosis of cellular-scale changes to environmental factors.
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Structure and Orientation Changes of ω-and γ-Gliadins at the Air-Water Interface : A PM-IRRAS Spectroscopy and Brewster Angle Microscopy Study
Auteur(s): Banc A., Desbat B., Renard Denis, Popineau Yves, Mangavel Cécile, Navailles Laurence
(Article) Publié:
Langmuir, vol. 23 p.13066 (2007)
Texte intégral en Openaccess :
Ref HAL: hal-00550429_v1
PMID 18031067
DOI: 10.1021/la702037k
WoS: 000251583000041
Exporter : BibTex | endNote
49 Citations
Résumé: Microscopic and molecular structures of ω- and γ-gliadin monolayers at the air-water interface were studied under compression by three complementary techniques: compression isotherms, polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS), and Brewster angle microscopy (BAM). For high molecular areas, gliadin films are homogeneous, and a flat orientation of secondary structures relative to the interface is observed. With increasing compression, the nature and orientation of secondary structures changed to minimize the interfacial area. The γ-gliadin film is the most stable at the air-water interface; its interfacial volume is constant with increasing compression, contrary to ω-gliadin films whose molecules are forced out of the interface. γ-Gliadin stability at a high level of compression is interpreted by a stacking model.
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