References of "Thomassin, Jean-Michel"
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See detailThermo-reversible reactions for the preparation of smart materials: recyclable covalently-crosslinked shape memory polymers
Defize, Thomas ULg; Riva, Raphaël ULg; Thomassin, Jean-Michel ULg et al

in Macromolecular Symposia (2011), 309/310(1), 154-161

[4+2] thermoreversible Diels-Alder cycloaddition has been used to crosslink star-shaped poly(ε-caprolactone) in order to produce networks based on strong carbon-carbon covalent bondings. Depending on the ... [more ▼]

[4+2] thermoreversible Diels-Alder cycloaddition has been used to crosslink star-shaped poly(ε-caprolactone) in order to produce networks based on strong carbon-carbon covalent bondings. Depending on the nature of the Diels-Alder reactants, these bonds can be thermoreversibly broken, allowing re-processing of the polymer matrix. [less ▲]

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See detailCaractérisation microstructurale de mousses polymères nanocomposites par microtomographie à rayons X
Plougonven, Erwan ULg; Tran, Minh Phuong ULg; Marchot, Pierre ULg et al

Poster (2011, November 29)

Les circuits électriques, fonctionnant à des fréquences de plus en plus élevées, sont responsables de l’augmentation de la pollution électromagnétique, et justifient le développement de blindages ... [more ▼]

Les circuits électriques, fonctionnant à des fréquences de plus en plus élevées, sont responsables de l’augmentation de la pollution électromagnétique, et justifient le développement de blindages efficaces. De nombreuses applications sont concernées, que ce soit dans les systèmes électroniques commerciaux, industriels, ou militaires, ou les systèmes antennaires. Récemment, des blindages sous forme de composites polymère/charges carbonées ont été largement développés pour leur nombreux avantages : plus légers, moins chers, plus absorbants, et plus facilement moulables. Une charge carbonée prometteuse est le nanotube de carbone car de par son facteur de forme, une concentration moindre est nécessaire pour une conductivité équivalente [1]. Afin d’améliorer l’absorption de l’énergie électromagnétique de ces composites (par rapport à leur réflectivité), ils sont moussés pour réduire leur constante diélectrique. Cette étape de moussage doit être rigoureusement contrôlée pour atteindre le niveau d’absorption ciblé. Deux techniques de moussage sont envisagées dans cette étude, à savoir le moussage en CO2 supercritique (par imprégnation de CO2 en condition supercritique, avant une dépressurisation rapide) et le freeze-drying (dissolution dans un solvant, suivi d’une lyophilisation de celui-ci). Ces deux méthodes génèrent des structures de porosité bien distinctes, avec une anisotropie apparente marquée dans le second cas. L’objectif est de caractériser ces structures par tailles moyennes de pores et mesures d’anisotropie, et leur lien avec l’efficacité de blindage. Dans cette optique, la caractérisation est effectuée par microtomographie à rayons X, une technique d’imagerie 3D non-destructive. Des acquisitions sont faites sur chaque échantillon, et la microstructure est analysée par traitement d’images. Vu la très faible atténuation des rayons X dans ce type de matériaux, et la limite de résolution de cette technique par rapport à la taille des pores et à l’épaisseur des parois, la séparation précise des pores par rapport à la matrice polymère s’avère difficile. Une segmentation classique n’étant pas applicable en préalable à des mesures quantitatives, la fonction d’autocorrélation est utilisée. Cette technique, habituellement utilisée en traitement du signal, est une méthode performante de mesure globale de l’anisotropie d’un matériau [2]. Elle permet également d’extraire une longueur caractéristique qui peut être liée à la taille des cellules. Les résultats mettent en évidence l’impact de la technique et des conditions de moussage sur la microstructure des mousses composites. [less ▲]

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See detailInfluence of nanoparticle-polymer interactions on the apparent migration behaviour of carbon nanotubes in an immiscible polymer blend
Tao, Fangfang; Nysten, Bernard; Baudouin, Anne-Christine et al

in Polymer (2011), 52(21), 4798-4805

We investigate the influence of nanoparticle–polymer interactions on the apparent migration behavior of multiwall carbon nanotubes (CNTs) in an immiscible polymer blend of ethylene-acrylate copolymer (EA ... [more ▼]

We investigate the influence of nanoparticle–polymer interactions on the apparent migration behavior of multiwall carbon nanotubes (CNTs) in an immiscible polymer blend of ethylene-acrylate copolymer (EA) and polyamide 12 (PA). The polymer-CNTs interaction is tuned by using different surface modification strategies, comprising grafting and coating. Poly(methyl methacrylate) (PMMA) and polystyrene (PS) are chosen as surface modifiers. The nanocomposite materials are prepared by melt-blending polymer-modified-CNTs in EA and PA. Polymer-grafted-CNTs tend to concentrate at the PA/EA interface, even if predispersed in PA, as opposed to pristine CNTs, which stay inside PA under the same circumstances. This new behavior is consistent with the morphology of PA/EA/(PMMA or PS) ternary blends and suggest a dominance of interfacial thermodynamics on CNTs localization. If we use polymer-coated-CNTs instead, the behavior depends on molar mass of the coating polymer. For low molar mass, it is similar to that of pristine CNTs and indicates desorption of the coating, owing to the weak interaction with the CNTs surface. Interestingly, we observe that long PS chains do not desorb and can drive the CNTs to the interface of the PA/EA blend. Moreover, the influence of kinetics is clearly observed through the dependence of CNTs interfacial confinement on dispersed droplet size. [less ▲]

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See detailPMMA/ carbon nanotube nanocomposite foams for EMI shielding application
Thomassin, Jean-Michel ULg; Vuluga, Daniela; Huynen, Isabelle et al

Conference (2011, August 30)

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See detailDesign of cross-linked semicrystalline poly(ε-caprolactone)-based networks with one-way and two-way shape-memory properties through Diels–Alder
Raquez, Jean-Marie; Vanderstappen, Sophie; Meyer, Franck et al

in Chemistry : A European Journal (2011), 17(36), 10135-10143

Cross-linked poly(ε-caprolactone) (PCL)-based polyesterurethane (PUR) systems have been synthesized through Diels–Alder reactions by reactive extrusion. The Diels–Alder and retro-Diels–Alder reactions ... [more ▼]

Cross-linked poly(ε-caprolactone) (PCL)-based polyesterurethane (PUR) systems have been synthesized through Diels–Alder reactions by reactive extrusion. The Diels–Alder and retro-Diels–Alder reactions proved to be useful for enhancing the molecular motion of PCL-based systems, and therefore their crystallization ability, in the design of cross-linked semicrystalline polymers with one-way and two-way shape-memory properties. Successive reactions between alpha,omega-diol PCL (PCL2), furfuryl alcohol, and methylene diphenyl 4,4′-diisocyanate straightforwardly afforded the alpha,omega-furfuryl PCL-based PUR systems, and subsequent Diels–Alder reactions with N,N-phenylenedimaleimide afforded the thermoreversible cycloadducts. The cross-linking density could be modulated by partially replacing PCL-diol with PCL-tetraol. Interestingly, the resulting PUR systems proved to be semicrystalline cross-linked polymers, the melting temperature of which (close to 45 °C) represented the switching temperature for their shape-memory properties. Qualitative and quantitative measurements demonstrated that these PUR systems exhibited one-way and two-way shape-memory properties depending on their cross-linking density. [less ▲]

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See detailPMMA/carbon nanotube nanocomposites foams for EMI shielding application
Thomassin, Jean-Michel ULg; Molenberg, Isabel; Huynen, Isabelle et al

Conference (2011, June 27)

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See detailAn efficient biphasic synthesis of polymer-grafted reduced graphite oxide based nanocomposites
Vuluga, Daniela ULg; Thomassin, Jean-Michel ULg; Molenberg, Isabel et al

Conference (2011, June 01)

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See detailProgress in cobalt-mediated radical polymerization
Debuigne, Antoine ULg; Hurtgen, Marie ULg; Piette, Yasmine ULg et al

Poster (2011, May 12)

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See detailMultifunctional hybrids for electromagnetic absorption
Huynen, Isabelle; Quievy, N.; Bailly, Christian et al

in Acta Materialia (2011), 59(8), 3255-3266

Electromagnetic (EM) interferences are ubiquitous in modern technologies and impact on the reliability of electronic devices and on living cells. Shielding by EM absorption, which is preferable over ... [more ▼]

Electromagnetic (EM) interferences are ubiquitous in modern technologies and impact on the reliability of electronic devices and on living cells. Shielding by EM absorption, which is preferable over reflection in certain instances, requires combining a low dielectric constant with high electrical conductivity, which are antagonist properties in the world of materials. A novel class of hybrid materials for EM absorption in the gigahertz range has been developed based on a hierarchical architecture involving a metallic honeycomb filled with a carbon nanotube-reinforced polymer foam. The waveguide characteristics of the honeycomb combined with the performance of the foam lead to unexpectedly large EM power absorption over a wide frequency range, superior to any known material. The peak absorption frequency can be tuned by varying the shape of the honeycomb unit cell. A closed form model of the EM reflection and absorption provides a tool for the optimization of the hybrid. This designed material sets the stage for a new class of sandwich panels combining high EM absorption with mass efficiency, stiffness and thermal management. [less ▲]

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See detailFunctionalization of carbon nanotubes by polymers using grafting to methods
Thomassin, Jean-Michel ULg; Jérôme, Robert ULg; Jérôme, Christine ULg et al

in Mittal, Vikas (Ed.) Surface modification of nanotube fillers (2011)

The huge research effort devoted to the chemical modification of CNTs by grafted macromolecules is driven by the need to enhance their affinity for a variety of environments, a necessary step for ... [more ▼]

The huge research effort devoted to the chemical modification of CNTs by grafted macromolecules is driven by the need to enhance their affinity for a variety of environments, a necessary step for designing advanced nanomaterials. This chapter aims at reviewing the until now investigated “grafting to” methods used for the surface modification of carbon nanotubes (CNTs) by polymers of various functionalities. Two major strategies are emphasized on the basis of the number of needed modification steps. The first technique consists in functionalizing the CNTs surface to promote in a second step the covalent anchoring of polymer chains bearing complementary reactive groups either at one chain-end or along the chain. The second approach is straightforward as result of the ability of the selected polymer to add directly onto the sp2 carbons of the CNTs surface. The major advantage of the “grafting onto” techniques is that the molecular characteristics (molecular weight, polydispersity, functionality,…) of the polymers can be tailored prior to the grafting reaction. Moreover, when using the proper controlled or living polymerization techniques and grafting conditions, polymers of well-defined architecture, functionality and properties can be easily anchored to the CNTs surface, which makes the “on-demand” tuning of the chemical properties of CNTs possible. [less ▲]

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See detailRecent Advances in Macromolecular Design via Cobalt-Mediated Radical Polymerization
Debuigne, Antoine ULg; Hurtgen, Marie ULg; Piette, Yasmine ULg et al

Conference (2011, April 13)

This communication will focuse on recent progress in the field of cobalt-mediated radical polymerization (CMRP). For example, the beneficial impact of cobalt complexes on the course of acrylate and vinyl ... [more ▼]

This communication will focuse on recent progress in the field of cobalt-mediated radical polymerization (CMRP). For example, the beneficial impact of cobalt complexes on the course of acrylate and vinyl chloride (VC) polymerizations will be discussed. The addition of conjugated unsaturated derivatives, like dienes, fullerenes and carbon nanotubes, onto (co)polymers preformed by CMRP has also been investigated. Similarities and differences between these radical addition processes will be presented as well as the potential applications of the resulting copolymers and carbon based materials for photodynamic therapy (PDT) and electromagnetic interferences (EMI) shielding. [less ▲]

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See detailAn efficient biphasic synthesis of polymer-grafted reduced graphite oxide based nanocomposites
Vuluga, Daniela ULg; Thomassin, Jean-Michel ULg; Molenberg, Isabel et al

Poster (2011, March 03)

Detailed reference viewed: 26 (4 ULg)