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Elaboration par la technique des plasmas froids de nouveaux catalyseurs métallocène supportés par un film polymère

Abstract : The work presented in this report concerns the fixation of a metallocen catalyst on a high density polyethylen film exposed to a carbon dioxide (CO2) cold plasma. It joins within the framework of researches led in the Laboratory for several years which aim at elaborating polymers materials displaying specific superficial properties. To reach this purpose, our approach consisted on one hand, in the study of the superficial modifications as well as the reactionnal mechanisms occurring in the interface plasma - polymer and on the other hand, of the exploitation of superficial carboxylic sites creating by the plasma treatment with the aim of the fixation of a 4-th generation catalyst.
The reactives species of the CO2 plasma (ions, metastables, ...) lead a modification of the superficial physico-chemical properties of the polymer. A fonctionnalisation by oxygenated groupings mainly occured. A superficial degradation as well as a crystallization and a reticulation are also observed. The superficial fonctionnalisation by carboxylic acid functions occurs according to a mechanism involving the CO2 active species of the plasma. The atomic oxygen (O3P and\or O1D) created during the plasma discharge seems widely responsible for the degradation process leading to a weak superficial roughness of the material as well as by the formation of volatile products (H and H2).
The fixation of the metallocen catalyst (Ind2MCl2) was realized by successive step on the treated support. The existence of a single catalytic specie hanging to the surface with a covalent bond allows the synthesis of polymers with narrow mass distribution. The re-use of the supported catalyst, without considerable loss of activity, or modification of the characteristics of the synthetized polymer, is also shown. A molecular modelling allows to define the meso conformation as being from an energy point of view the most stable and it, in all the more marked a way as the interactions between aromatic ligands increase. The nature of the tacticity of the synthetized polystyrene is explained by the conformation of the supported catalyst.
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https://tel.archives-ouvertes.fr/tel-00009643
Contributor : Nicolas Medard <>
Submitted on : Friday, July 1, 2005 - 4:54:03 PM
Last modification on : Tuesday, March 31, 2020 - 3:20:50 PM
Long-term archiving on: : Monday, September 17, 2012 - 3:45:35 PM

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  • HAL Id : tel-00009643, version 1

Citation

Nicolas Medard. Elaboration par la technique des plasmas froids de nouveaux catalyseurs métallocène supportés par un film polymère. Catalyse. Université du Maine, 2000. Français. ⟨tel-00009643⟩

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