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(467) Articles dans des revues
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Estimation of the Interfacial Tension Between the Lamellar and the Sponge Phases of a Lyotropic System 
Auteur(s): Blanc C.
(Article) Publié:
Soft Materials, vol. 1 p.63 (2002)
Ref HAL: hal-01212576_v1
DOI: 10.1081/SMTS-120016742
WoS: 000221241200005
Exporter : BibTex | endNote
3 Citations
Résumé: In lyotropic systems, the sponge and the lamellar phases possess the same local structure: a membrane made of a bilayer of surfactants. In the quasiternary lyotropic system CPCl/brine/hexanol, the bilayer is continuous through the interface between the lamellar and the sponge phases. A model based on this phenomenon has predicted a very low value of the interfacial free energy. The study of hydrodynamic relaxation time of distorted spherical lamellar droplets gives an estimation of the interfacial tension value. Results confirm the validity of the model and the dependence on membrane volume fraction is explained by a simple scaling law.
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Tank treading and unbinding of deformable vesicles in shear flow: determination of the lift force.
Auteur(s): Abkarian M., Lartigue Colette, Viallat Annie
(Article) Publié:
Physical Review Letters, vol. 88 p.068103 (2002)
PMID 11863856
Résumé: Deformation and tank-treading motion of flaccid vesicles in a linear shear flow close to a wall are quantitatively studied by light microscopy. Velocities of bounded vesicles obey Goldman's law established for rigid spheres. A progressive tilt and a transition of unbinding of vesicles are evidenced upon increasing the shear rate, gamma;. These observations disclose the existence of a viscous lift force, F(l), depending on the viscosity eta of the fluid, the radius R of the vesicle, its distance h from the substrate, and a monotonous decreasing function f(1-v) of the reduced volume v, in the following manner: F(l) = eta(gamma)(R(3)/h)f(1-v). This relation is valid for vesicles both close to and farther from the substrate.
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Simulation of aggregate structure and SANS-spectra in filled elastomers
Auteur(s): Oberdisse J., Rharbi Y., Boué F.
(Article) Publié:
Computational And Theoretical Polymer Science, vol. 10 p.207-217 (2000)
Texte intégral en Openaccess : 
Ref HAL: hal-05315023_v1
DOI: 10.1016/S1089-3156(99)00081-1
Exporter : BibTex | endNote
Résumé: We report preliminary simulations of anisotropic scattering from aggregates of small hard spherical particles embedded in an elastic polymer matrix, using simple geometrical methods. First we build several types of aggregates in three dimensions: crystalline, amorphous compact, fractals, of different numbers of particles and varying polydispersity. We then turn to the spectra of deformed samples simulated in two dimensions. We impose an affine displacement inside the matrix to the fillers, which can be isolated particles or small aggregates, and account for the collisions which arise due to lateral shrinking of the material. The two-dimensional scattering spectra are shown and discussed. They reproduce experimentally observed isointensity curves: ellipses, banana-shaped maxima and splitting of these maxima in four spots. Finally, we explore the consequences of the reduction to two dimensions via statistics of the number of collisions. It is found that even if collisions are more important in 3 dimensions, the behavior is qualitatively similar in two and three dimensions.
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Universal aging features in the restructuring of fractal colloidal gels
Auteur(s): Cipelletti L., Manley S, Ball Rc, Weitz Da
(Article) Publié:
Physical Review Letters, vol. 84 p.2275-2278 (2000)
Résumé: We use multispeckle dynamic light scattering to measure the dynamic structure factor, f(q, tau), of gels formed by aggregation of colloids. Although the gel is an elastic solid, f(q, tau) nearly completely decays on long time scales, with an unusual form, f(q, tau) similar to exp{-(tau/tau(f))(mu)}, with mu approximate to 1.5 and with tau(f) proportional to q(-1) A model for restructuring of the gel with aging correctly accounts for this behavior. Aging leads to a dramatic increase in tau(f) however, all data can be scaled on a single master curve, with tau(f) asymptotically growing linearly with age. This behavior is strikingly similar to that predicted for aging in disordered glassy systems, offering convincing proof of the universality of these concepts.
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Molecular design of sol-gel derived hybrid organic-inorganic nanocomposites
Auteur(s): Sanchez C., Lebeau B., Ribot François, In M.
(Article) Publié:
Journal Of Sol-Gel Science And Technology, vol. 19 p.31-38 (2000)
Texte intégral en Openaccess :
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