References of "Calberg, Cédric"
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See detailSolid-state NMR study of intercalated species in poly(epsilon-caprolactone)/clay nanocomposites
Hrobarikova, J.; Robert, J. L.; Calberg, Cédric ULg et al

in Langmuir (2004), 20(22), 9828-9833

The structure and dynamics of surfactant and polymer chains in intercalated poly(epsilon-caprolactone)/clay nanocomposites are characterized by (31)P magic-angle spinning (MAS) and (13)C cross ... [more ▼]

The structure and dynamics of surfactant and polymer chains in intercalated poly(epsilon-caprolactone)/clay nanocomposites are characterized by (31)P magic-angle spinning (MAS) and (13)C cross-polarization MAS NMR techniques. To obtain hybrid materials with the low polymer content required for this study, in situ intercalative polymerization was performed by adapting a published procedure. After nanocomposite formation, the chain motion of the surfactant is enhanced in the saponite-based materials but reduced in the Laponite ones. Compared to the starting clay, the trans conformer population of the surfactant hydrocarbon chain in the nanocomposite decreases for the saponite systems. Mobility of the polymer chain is higher in the nanocomposites than in the bulk phase. The charge of the modified saponite does not significantly influence chain mobility in the nanocomposites. [less ▲]

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See detailFunctionalization of multi-walled carbon nanotubes by electrografting of polyacrylonitrile
Petrov, Petar; Lou, Xudong; Pagnoulle, Christophe et al

in Macromolecular Rapid Communications (2004), 25(10), 987-990

As a result of their unique architecture and remarkable mechanical and electrical properties[1,2] carbon nanotubes (CNTs)[3] have great potential that remains, however, un-exploited because of poor ... [more ▼]

As a result of their unique architecture and remarkable mechanical and electrical properties[1,2] carbon nanotubes (CNTs)[3] have great potential that remains, however, un-exploited because of poor dispersibility in liquids and problems of processability, Major efforts have, therefore, been devoted towards any modification of the CNTs that could improve their handling[4,5] Typically, chemical modification of CNTs is based on severe oxidation processes that often damage the tubes[5] Mild and single-step electrochemical modification of CNTs is a valuable alternative to the oxidative treatment. There are several reports in the scientific literature on the electrochemical functionalization of CNTs by electroreduction of diazonium salts,[6-8] and on the halogenation of MWNTs by electrolysis However, the grafting of polymers instead of low-molecular-weight compounds onto CNTs by an electrochemical process is a possible strategy for dispersing CNTs in polymer matrices and improving the mechanical properties of CNT-based nanocomposites.. For the past few years, we have been interested in the electiografting of insulating polymer films onto cathodic surfaces, for example, nickel and glassy carbon, provided that the potential and solvent are properly selected.[10-15] These films are designated as "grafted films", because they have the unique property of remaining attached to the electrode surface even when they are prepared and kept in a solvent in which the polymer is highly soluble. The extension of this technique to CNTs has been explored with acrylonitrile as monomer. This communication aims at reporting the functionaliza-tion of multi-walled carbon nanotubes (MWNTs) by the electropolymerization of acrylonitrile. [less ▲]

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See detailStructure and dynamics of cationic surfactants intercalated in synthetic clays
Müller, Robert; Hrobarikova, Jana; Calberg, Cédric ULg et al

in Langmuir (2004), 20(7), 2982-2985

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See detailSolid-state NMR study of poly(epsilon-caprolactone)/clay nanocomposites
Calberg, Cédric ULg; Jérôme, Robert ULg; Grandjean, Jean ULg

in Langmuir (2004), 20(5), 2039-2041

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See detailExfoliated polylactide/clay nanocomposites by in-situ coordination-insertion polymerization
Paul, Marie-Amélie; Alexandre, Michaël ULg; Degée, Philippe et al

in Macromolecular Rapid Communications (2003), 24(9), 561-566

Poly(L-lactide)/layered aluminosilicate nanocomposites were synthesized in bulk by ring-opening polymerization in the presence of two organo-modified montmorillonites. When the organo-modifier consisted ... [more ▼]

Poly(L-lactide)/layered aluminosilicate nanocomposites were synthesized in bulk by ring-opening polymerization in the presence of two organo-modified montmorillonites. When the organo-modifier consisted of an ammonium cation bearing primary hydroxyl groups, polymerization was initiated by the alcohol functions after adequate activation. The growing polymer chains were directly "grafted" onto the clay surface through the hydroxyl-functionalized ammonium cations yielding exfoliated nano-composites with enhanced thermal stability. [less ▲]

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See detailSupercritical carbon dioxidce technology: a new method for the preparation of green materials
Stassin, Fabrice; Calberg, Cédric ULg; Pagnoulle, Christophe et al

Poster (2003, May 16)

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See detailPolymer functionalized multi-walled carbon nanotubes
Petrov, Petar; Pagnoulle, Christophe; Stassin, Fabrice et al

Poster (2003, May 16)

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See detailPolymer/layered silicate nanocomposites by combined intercalative polymerization and melt intercalation: a masterbatch process
Lepoittevin, Bénédicte; Pantoustier, Nadège; Devalckenaere, Myriam et al

in Polymer (2003), 44(7), 2033-2040

Poly(ε-caprolactone) (PCL) and poly(vinyl chloride) (PVC) layered silicate nanocomposites were prepared by combination of intercalative polymerization and melt intercalation. In a first step, high clay ... [more ▼]

Poly(ε-caprolactone) (PCL) and poly(vinyl chloride) (PVC) layered silicate nanocomposites were prepared by combination of intercalative polymerization and melt intercalation. In a first step, high clay content PCL nanocomposites were prepared by in situ polymerization of -caprolactone intercalated between selected organo-modified silicate layers. The polymerization was catalyzed with dibutyltin dimethoxide in the presence of montmorillonites, the surface of which were previously exchanged with (functionalized) long alkyl chains ammonium cations. Then, these highly filled PCL nanocomposites were added as masterbatches in commercial PCL and PVC by melt blending. The intercalation of PCL chains within the silicate layers by in situ polymerization proved to be very efficient, leading to the formation of intercalated and/or exfoliated structures depending on the organo-clay. These masterbatches were readily dispersed into the molten PCL and PVC matrices yielding intercalated/exfoliated layered silicate nanocomposites which could not be obtained by melt blending the matrix directly with the same organo-modified clays. The formation of nanocomposites was assessed both by X-ray diffraction and transmission electronic microscopy. Interestingly, this so-called 'masterbatch' two-step process allowed for preparing PCL nanocomposites even with non-modified natural clay, i.e. sodium montmorillonite, which showed a material stiffness much higher than the corresponding microcomposites recovered by direct melt intercalation. The thermal stability of PCL nanocomposites as a function of clay content was investigated by thermogravimetry (TGA). [less ▲]

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See detailPoly(epsilon-caprolactone)/clay nanocomposites by in-situ intercalative polymerization catalyzed by dibutyltin dimethoxide
Lepoittevin, Bénédicte; Pantoustier, Nadège; Devalckenaere, Myriam et al

in Macromolecules (2002), 35(22), 8385-8390

Poly(epsilon-caprolactone)/clay nanocomposites were prepared by in-situ ring-opening polymerization of epsilon-caprolactone by using dibutyltin dimethoxide as an initiator/catalyst. A nonmodified Na ... [more ▼]

Poly(epsilon-caprolactone)/clay nanocomposites were prepared by in-situ ring-opening polymerization of epsilon-caprolactone by using dibutyltin dimethoxide as an initiator/catalyst. A nonmodified Na+-montmorillonite and two montmorillonites surface-modified by dimethyl 2-ethylhexyl (hydrogenated tallow alkyl) and methyl bis(2-hydroxyethyl) (hydrogenated tallow alkyl) ammonium cations, respectively, were used. The evolution of molecular weights was followed in relation to silicate surface modification and clay concentration. The alcohol-bearing organo-modified clay was a co-initiator for the polymerization reaction and thus controlled the molecular weight of the PCL chains. Furthermore, the number-average molecular weight of the growing PCL chains linearly increased with the monomer conversion. Nanocomposites were analyzed by small-angle X-ray diffraction, transmission electron microscopy, and thermogravimetry. The clay dispersion depended on the structure of the alkylammonium used to make the clay more hydrophobic. Exfoliated nanocomposites were formed when hydroxyl-containing alkylammonium. was used; otherwise, intercalated structures were reported. Thermogravimetric analyses showed a higher degradation temperature for the exfoliated structures than for the intercalated ones, both of them exceeding the degradation temperature of unfilled poly(epsilon-caprolactone). [less ▲]

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See detailBiodegradable polyester layered silicate nanocomposites based on poly(epsilon-caprolactone)
Pantoustier, Nadège; Lepoittevin, Bénédicte; Alexandre, Michaël ULg et al

in Polymer Engineering & Science (2002), 42(9), 1928-1937

Nanocomposites based on biodegradable poly(epsilon-caprolactone) (PCL) and layered silicates (montmorillonite, MMT) were prepared either by melt intercalation with PCL or by in situ ring-opening ... [more ▼]

Nanocomposites based on biodegradable poly(epsilon-caprolactone) (PCL) and layered silicates (montmorillonite, MMT) were prepared either by melt intercalation with PCL or by in situ ring-opening polymerization of epsilon-caprolactone as promoted by the so-called coordination-insertion mechanism. Both non-modified clays (Na+-MMT) and silicates modified by various alkylammonium cations were studied. Mechanical and thermal properties were examined by tensile testing and thermogravimetric analysis. Even at a filler content as low as 3 wt% of inorganic layered silicate, the PCL-layered silicate nanocomposites exhibited improved mechanical properties (higher Young's modulus) and increased thermal stability as well as enhanced flame retardant characteristics as a result of a charring effect. It was shown that the formation of PCL-based nanocomposites depended not only on the nature of the ammonium cation and related functionality but also on the selected synthetic route, melt intercalation vs. in situ intercalative polymerization. Interestingly enough, when the intercalative polymerization of epsilon-caprolactone was carried out in the presence of MMT organo-modified with ammonium cations bearing hydroxyl functions, nanocomposites with much improved mechanical properties were recovered. Those hybrid polyester layered silicate nanocomposites. were characterized by a covalent bonding between the polyester chains and the clay organo-surface as a result of the polymerization mechanism, which was actually initiated from the surface hydroxyl functions adequately activated by selected tin (II) or tin (IV) catalysts. [less ▲]

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See detailLayered silicate/polyester nanohybrids by controlled ring-opening polymerization
Lepoittevin, Bénédicte; Pantoustier, Nadège; Alexandre, Michaël ULg et al

in Macromolecular Symposia (2002), 183

In this study, layered silicate/aliphatic polyester nanohybrids were synthesized by ring-opening polymerization of c-caprolactone as promoted by the so-called coordination-insertion mechanism. These ... [more ▼]

In this study, layered silicate/aliphatic polyester nanohybrids were synthesized by ring-opening polymerization of c-caprolactone as promoted by the so-called coordination-insertion mechanism. These nanocomposites were formed in presence of montmorillortite surface-modified by ammonium cations bearing hydroxyl group(s), such as bis(2-hydroxyethyl)methyl (hydrogenated tallow alkyl) ammonium. The lactone polymerization could in initiated by all the hydroxyl functions available at the clay surface, after activation into either tin(II) or AI(III) alkoxide active species. Hybrid nanocomposites were accordingly generated through the covalent grafting of every polyester chain onto the filler surface. Surface-grafted polycaprolactone (PCL) chains were untied and isolated by ionic exchange reaction with LiCl in THF solution and molar masses were measured by size exclusion chromatography. The PCL molar masses could be controlled and readily tuned by the content of hydroxyl groups available at the clay surface. Interestingly, initiation reaction by aluminum trialkoxide active species yielded grafted PCL chains characterized by very narrow molecular weight distribution (M-w/M(n)similar to1.2). These polyester-grafted layered silicate nanohybrids displayed complete exfoliation of silicate sheets as shown by X-ray diffraction (XRD) and transmission electron microscopy (TEM). [less ▲]

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See detailPoly(epsilon-caprolactone)/clay nanocomposites prepared by melt intercalation: mechanical, thermal and rheological properties
Lepoittevin, Bénédicte; Devalckenaere, Myriam; Pantoustier, Nadège et al

in Polymer (2002), 43(14), 4017-4023

(Nano)composites of poly(epsilon-caprolactone) (PCL) were prepared by melt blending the polymer with natural Na+ montmorillonite and montmorillonite modified by hydrogenated tallowalkyl (HTA)-based ... [more ▼]

(Nano)composites of poly(epsilon-caprolactone) (PCL) were prepared by melt blending the polymer with natural Na+ montmorillonite and montmorillonite modified by hydrogenated tallowalkyl (HTA)-based quaternary ammonium cations, such as dimethyl 2-ethylhexyl HTA ammonium and methyl bis(2-hydroxyethyl) HTA ammonium. Microcomposites or nanocomposites were prepared depending on whether neat or modified montmorillonites was used, as assessed by X-ray diffraction and transmission electron microscopy. Mechanical and thermal properties were studied as a function of the filter content by tensile testing, Izod impact testing, thermogravimetric analysis and differential scanning calorimetry. The rheological behaviour at 80 degreesC was also analysed in relation to the structure and content of the layered silicate. Effect of exfoliated silicates on the mechanical properties, thermal stability and flame resistance of PCL was considered. Stiffness and thermal stability improved with the filler loading until a content of 5 wt%. Further loading resulted in the levelling off and possibly in a decrease of these properties. A marked charring effect was observed upon exposure to a flame. [less ▲]

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See detailPolyester layered silicate nanohybrids by controlled grafting polymerization
Lepoittevin, Bénédicte; Pantoustier, Nadège; Alexandre, Michaël ULg et al

in Journal of Materials Chemistry (2002), 12(12), 3528-3535

Poly( epsilon-caprolactone) (PCL) layered silicate nanohybrids were synthesized by ring opening polymerization of epsilon-caprolactone according to a well-controlled coordination-insertion mechanism ... [more ▼]

Poly( epsilon-caprolactone) (PCL) layered silicate nanohybrids were synthesized by ring opening polymerization of epsilon-caprolactone according to a well-controlled coordination-insertion mechanism. Montmorillonites were surface-modified by non functional (trimethylhexadecylammonium) and hydroxy functional alkylammonium cations, i.e., (2-hydroxyethyl) dimethylhexadecylammonium. The hydroxy functions available at the clay surface were activated into tin( II or IV) or Al(III) alkoxide initiators for lactone polymerization, thus yielding surface-grafted PCL chains. The surface-grafted PCL chains were recovered by an ionic exchange reaction with lithium chloride and they were analyzed by size exclusion chromatography. The PCL molar mass was measured as a function of the hydroxy content of the clay that was modulated by exchanging the Na cations with mixtures of non-functional and hydroxy functional ammonium cations of different compositions. Nanohybrids were also characterized by small-angle X-ray diffraction, transmission electron microscopy and thermogravimetry. The PCL molar mass and the nanocomposite morphology (i.e., exfoliation and/or intercalation) were readily tuned by the content of the hydroxy groups available at the clay surface. Surface-grafted aluminium trialkoxide species proved highly efficient in initiating polymerization that leads to PCL chains of controlled molar mass and narrow molecular weight distribution with polydispersity indices as low as 1.2. [less ▲]

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See detailFull-electrochemical preparation of conducting/insulating binary polymer films
Jérôme, Christine ULg; Geskin, V.; Lazzaroni, Roberto et al

in Chemistry of Materials (2001), 13(5), 1656-1664

Binary polymer films consisting of an insulating polymer and a conducting polymer have been successfully prepared by sequential electropolymerization of the parent monomers. The insulating polymer ... [more ▼]

Binary polymer films consisting of an insulating polymer and a conducting polymer have been successfully prepared by sequential electropolymerization of the parent monomers. The insulating polymer (polyacrylonitrile or polyethylacrylate) is formed under cathodic polarization in a potential range where the growing chains are chemically grafted onto the nickel or carbon electrode. The conducting polymer (polybithiophene or polypyrrole) is formed by electrooxidation of the parent monomer. The electrochemical reactions and the electrochemical properties of the films have been analyzed by cyclic voltammetry and chronoamperometry. The influence of the main experimental parameters on the composition and morphology of the films has been investigated by X-ray photoelectron spectroscopy and atomic force microscopy. This approach strongly improves the adhesion of the conducting polymer as a result of its combination with the grafted polyacrylonitrile. This combination of insulating and conducting polymers is a way to tune the electroactivity of the conjugated chains. [less ▲]

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See detailPoly(e-caprolactone) layered silicate nanocomposites: effect of clay surface modifiers on the melt intercalation process
Pantoustier, Nadège; Alexandre, Michaël ULg; Degée, Philippe et al

in e-Polymers (2001), (9), 1-9

Nanocomposites based on biodegradable poly(e-caprolactone) (PCL) and layered silicates (montmorillonite) modified by various alkylammonium cations were prepared by melt intercalation. Depending on whether ... [more ▼]

Nanocomposites based on biodegradable poly(e-caprolactone) (PCL) and layered silicates (montmorillonite) modified by various alkylammonium cations were prepared by melt intercalation. Depending on whether the ammonium cations contain non-functional alkyl chains or chains terminated by carboxylic acid or hydroxyl functions, microcomposites or nanocomposites were recovered as shown by X-ray diffraction and transmission electron microscopy. Mechanical and thermal properties were examined by tensile testing and thermogravimetric analysis. The layered silicate PCL nanocomposites exhibited some improvement of the mechanical properties (higher Young's modulus) and increased thermal stability as well as enhanced flame retardant characteristics as result of a charring effect. This communication aims at reporting that the formation of PCL-based nanocomposites strictly depends on the nature of the ammonium cation and its functionality, but also on the selected synthetic route, i.e. melt intercalation vs. in situ intercalative polymerization. Typically, protonated w-aminododecanoic acid exchanged montmorillonite allowed to intercalate e-caprolactone monomer and yielded nanocomposites upon in situ polymerization, whereas they exclusively formed microcomposites when blended with preformed PCL chains. In other words, it is shown that the formation of polymer layered silicate nanocomposites is not straightforward and cannot be predicted since it strongly depends on parameters such as ammonium cation type and functionality together with the production procedure, i.e., melt intercalation, solvent evaporation or in situ polymerization [less ▲]

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See detailThe use of conducting polymers as cathodes for the electrochemical deposition of magnetic transition metal/rare alloys
Martinot, Lucien; Leroy, Delphine ULg; Zhan, H. et al

in Journal of Materials Chemistry (2000), 10(3), 729-735

We report the electrodeposition of Cu and Ni in aqueous solutions together with the deposition of lanthanides (Gd, Sm, Dy, Tb) and amorphous magnetic alloys of lanthanides with transition metals (Fe, Co ... [more ▼]

We report the electrodeposition of Cu and Ni in aqueous solutions together with the deposition of lanthanides (Gd, Sm, Dy, Tb) and amorphous magnetic alloys of lanthanides with transition metals (Fe, Co) onto various polymer cathodes in formamide solutions. We used conducting polymers (polypyrrole, PPy; polyethylenedioxythiophene, PEDOT) sprayed on different substrates and in addition composite materials based on carbon black (CB) mixed either with polyethylene (PE) or with polycarbonate (PC). In the latter case, the conducting material is easily shaped out in various forms. When deposited on some of these substrates, the alloys appear as an interesting material for magneto-optic recording. The electrochemical process was used for the preparation of Gd/Co and Dy/Fe alloys for which the measured coercitive fields ranged from 250–300 Oe (Dy/Fe) to about 350 Oe (Gd/Fe). We demonstrated also the feasibility of an additional electrografting of a transparent protective layer of polyacrylonitrile (PAN) in order to avoid the corrosion of the alloys by the atmosphere. [less ▲]

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See detailElectrical and dielectric properties of carbon black filled co-continuous two-phase polymer blends
Calberg, Cédric ULg; Blacher, Silvia ULg; Gubbels, F. et al

in Journal of Physics D - Applied Physics (1999), 32(13), 1517-1525

The electrical and dielectric properties of co-continuous polystyrene (PS)/ρoly(methylmethacrylate)(PMMA) blends loaded with carbon black (CB) of a special grade (BP 1000) have been studied. They strongly ... [more ▼]

The electrical and dielectric properties of co-continuous polystyrene (PS)/ρoly(methylmethacrylate)(PMMA) blends loaded with carbon black (CB) of a special grade (BP 1000) have been studied. They strongly depend on the selective localization of the CB particles at the blend interface quite consistently with the double percolation concept. The interfacial localization of CB contributes to the stabilization of the phase morphology against thermal post treatment. Nevertheless, the sample annealing has a very favourable effect on the percolation threshold that decreases The composition range in which phases are co-continuous is also increased by the addition of the filler. Dispersion of the conductance and the dielectric constant has been measured in the wide frequency range 10-4-108 Hz for blends containing 0-5 wt% CB. On the basis of these results, the mechanism of electrical transport (trapping, hopping, tunnelling, percolation) has been discussed in relation to the CB loading and the optimum loading has been identified for the electrical and dielectric properties to be stable and reproducible [less ▲]

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