References of "Legras, Roger"
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See detailElectrodeposition of mixed adherent thin films of poly(ethyl acrylate) and polyacrylonitrile onto nickel
Baute, Noëlle; Geskin, Victor M; Lazzaroni, Roberto et al

in e-Polymers (2004), (63), 1-20

Adherent thin polymer films have been prepared by sequential electrodeposition of ethyl acrylate (EA) and acrylonitrile (AN) onto nickel. Their composition has been studied by IR spectroscopy and time of ... [more ▼]

Adherent thin polymer films have been prepared by sequential electrodeposition of ethyl acrylate (EA) and acrylonitrile (AN) onto nickel. Their composition has been studied by IR spectroscopy and time of flight-secondary ion mass spectrometry. Morphology and thickness have been analyzed by atomic force microscopy and ellipsometry, respectively, and compared to single component films of PEA and PAN. No microphase separation was detected in the mixed PEA/PAN films. These show a granular morphology comparable to that of PAN films. The grains contain the two constitutive polymers, as confirmed by the selective thermal degradation of PEA. [less ▲]

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See detailProbing thermoplastic matrix-carbon fiber interphases. 1. Preferential segregation of low molar mass chains to the interface
Carlier, V.; Sclavons, M.; Jonas, Alain M et al

in Macromolecules (2001), 34(11), 3725-3729

The molecular mobility of polystyrene (PS) chains near the surface of carbon fibers was investigated. The glass transition temperature of very thin coatings deposited on carbon fibers was measured by ... [more ▼]

The molecular mobility of polystyrene (PS) chains near the surface of carbon fibers was investigated. The glass transition temperature of very thin coatings deposited on carbon fibers was measured by supported DMTA in order to probe the properties of the thermoplastic interphase. Depending on the fiber impregnation method from the melt or from solution, Tg changed in an opposite way for the thinnest coatings, decreasing with coating thickness in the case of impregnation in the melt and increasing when a polymer solution was used. This observation is explained by degradation of PS in the melt and subsequent preferential segregation of low molar mass chains to the interface. This conclusion is supported by the study of the Tg of coatings made from a bimodal molar mass distribution. [less ▲]

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See detailSurface Modification of Polycarbonate and Poly(ethyleneterephthalate) Films and Membranes by Polyelectrolyte Deposition
Dauginet, Laurence; Duwez, Anne-Sophie ULg; Legras, Roger et al

in Langmuir (2001), 17

The surface modification by chemical or physical adsorption of a polyelectrolyte (polyallylamine, PAH) was established using hydrolyzed polycarbonate (PC) and poly(ethylene terephthalate) (PET) thick and ... [more ▼]

The surface modification by chemical or physical adsorption of a polyelectrolyte (polyallylamine, PAH) was established using hydrolyzed polycarbonate (PC) and poly(ethylene terephthalate) (PET) thick and thin films. Contact angle data indicated changes in the hydrophilicity of PET film surfaces in terms of the chemical treatment. XPS analysis showed that the immobilization of PAH on PET and PC films was effective and that the amount of chemically or/and physically bounded PAH depends on the pH of the electrolyte solution used for the adsorption. Similar treatments have been successfully applied to polymeric track-etched membranes. These modified membranes have been used as templates for the synthesis of polypyrrole (PPy) nanotubules. FE-SEM analysis showed that much thicker PPy tubules were obtained in modified membranes than in virgin ones. This indicates that the surface chemistry of the pore walls plays an important role in the morphology of the nanostructures synthesized within the pores [less ▲]

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See detailElectrochemical synthesis of conjugated polymer wires and nanotubules
Jérôme, Christine ULg; Demoustier-Champagne, Sophie; Legras, Roger et al

in Chemistry : A European Journal (2000), 6(17), 3089-3093

Two electrochemical methods designed for the synthesis of polypyrrole (PPy) wires and nanotubules are the topic of this paper. The concept that allows the morphology of PPy to be controlled is discussed ... [more ▼]

Two electrochemical methods designed for the synthesis of polypyrrole (PPy) wires and nanotubules are the topic of this paper. The concept that allows the morphology of PPy to be controlled is discussed for each method, and the performances of the two complementary techniques are compared in terms of dimension, shape and conductivity of PPy. [less ▲]

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See detailSynthesis and bulk characterization of new P(CB-b-S) diblock copolymers
Stone, V. W.; Jonas, Alain M; Legras, Roger et al

in Journal of Polymer Science. Part A, Polymer Chemistry (1999), 37(2), 233-244

Strongly asymmetric chlorinated polybutadiene-b-polystyrene, [P((CB)x-b-(PS)y)] diblock copolymers with increasing x/(x + y) ratios (up to 5.2 mol %) have been synthesized by the selective chlorination of ... [more ▼]

Strongly asymmetric chlorinated polybutadiene-b-polystyrene, [P((CB)x-b-(PS)y)] diblock copolymers with increasing x/(x + y) ratios (up to 5.2 mol %) have been synthesized by the selective chlorination of the polybutadiene (PB) block in solution. Chlorination has been performed in anhydrous dichloromethane added with an antioxidant [2,2-methylenebis-(6-tert-butyl-4-methyl-phenol)], at -50°C, under a continuous Ar flow and in the dark. Under the optimized experimental conditions, the PB chlorination is not complete, but the PS block is left unmodified. Even in the presence of a large chlorine excess (Cl2/butene unit molar ratio of 2.5), the experimental degree of chlorination of homo PB does not exceed 85%. The chlorinated copolymers have been characterized by 1H-NMR, IR spectroscopy, size-exclusion chromatography, and elemental analysis. The chlorinated copolymers have also been studied by DSC and SAXS after annealing at 150°C. Although at this temperature the parent homopolymers are immiscible, no microphase separation has been observed for the block copolymers. [less ▲]

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See detailElectrochemically synthesized polypyrrole nanotubules : effects of different experimental conditions
Demoustier-Champagne, Sophie; Ferain, Etienne; Jérôme, Christine ULg et al

in European Polymer Journal (1998), 34(12), 1767-1774

Nanotubules of polypyrrole (PPy) were electrochemically synthesized using the pores of nanoporous polycarbonate (PC) particle track-etched membranes (PTM) as templates. The influence of some conditions of ... [more ▼]

Nanotubules of polypyrrole (PPy) were electrochemically synthesized using the pores of nanoporous polycarbonate (PC) particle track-etched membranes (PTM) as templates. The influence of some conditions of electrosynthesis (electrochemical method, monomer concentration, electrolyte concentration and nature) on the kinetics of pyrrole electropolymerization and on the morphology of the obtained nanomaterials has been investigated. In particular, the empirical kinetics of the electrochemical generation of polypyrrole-perchlorate (PPy-ClO4) from aqueous solution, at 0.8 V (vs SCE) was followed by electrical charges measurement. The orders with respect to pyrrole and LiClO4 are 0.34 and 0.70 respectively. The electrogeneration of polypyrrole-polystyrenesulfonate (PPy-PSS) was also followed and shows that an increase of the electrolyte concentration increases the polymerization rate at constant potential. Finally, the morphology of PPy nanotubules doped with LiClO4 and NaPSS has been studied by high resolution emission SEM and by TEM. [less ▲]

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See detailDynamic mechanical thermal and infrared analyses of polyacrylonitrile "electrografted" onto a metal
Calberg, Cédric ULg; Mertens, Marc; Baute, Noëlle et al

in Journal of Polymer Science. Part B, Polymer Physics (1998), 36(4), 543-553

Polyacrylonitrile (PAN) films have been grafted onto copper electrodes by cathodic polarization and analyzed by infrared spectroscopy and dynamic mechanical thermal analysis (DMTA). The dynamic mechanical ... [more ▼]

Polyacrylonitrile (PAN) films have been grafted onto copper electrodes by cathodic polarization and analyzed by infrared spectroscopy and dynamic mechanical thermal analysis (DMTA). The dynamic mechanical response shows two or three transitions depending on the film thickness and the potential deposition. The viscoelastic properties of ungrafted PAN films, e.g., solvent cast films of commercially available PAN, are deeply different from those of electrografted films. The experimental data support that ungrafted chains are paracrystalline in contrast to the grafted ones which are essentially amorphous. Moreover, the irreversible transformation of the grafted PAN chains observed beyond 225°C is confirmed by Fourier transform infrared (FTIR) analysis and ascribed to an intramolecular cyclization of PAN into polyimine. This reaction occurs rapidly and at a comparatively low temperature with respect to ungrafted PAN, which suggests that the grafted chain configuration might be predominantly isotactic. The isotacticity and the amorphous structure appear to decrease as the thickness of the PAN film is increased. Literature data and the herein reported observations would suggest a dependence of the amorphous structure of PAN on the chain isotacticity. [less ▲]

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See detailCharacterization of polyacrylonitrile films grafted onto nickel by ellipsometry, atomic force microscopy and X-ray reflectivity
Calberg, Cédric ULg; Mertens, Marc; Jérôme, Robert ULg et al

in Thin Solid Films (1997), 310(1-2), 148-155

The thickness and roughness of polyacrylonitrile films electrografted on a nickel surface have been measured by ellipsometry, atomic force microscopy and X-ray reflectivity. From combined ellipsometry and ... [more ▼]

The thickness and roughness of polyacrylonitrile films electrografted on a nickel surface have been measured by ellipsometry, atomic force microscopy and X-ray reflectivity. From combined ellipsometry and X-ray reflectivity measurements, accurate values for the refractive indices of polyacrylonitrile and nickel have been derived at a 6328-Åwavelength. Dependence of the film thickness on the monomer concentration has been quantified for the first time. Furthermore, the thickness of the polyacrylonitrile (PAN) film is related to the nature of the solvent, depending on whether it is a good solvent for PAN (dimethylformamide; DMF) or not (acetonitrile; ACN). [less ▲]

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