Thèse soutenue

Etudes cinétiques d'un polymère supramoléculaire
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Auteur / Autrice : Benjamin Jouvelet
Direction : Laurent Bouteiller
Type : Thèse de doctorat
Discipline(s) : Physique et Chimie des Matériaux
Date : Soutenance en 2013
Etablissement(s) : Paris 6

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Résumé

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Appropriately designed bis-urea monomers dissolved in apolar solvent self-assembled through intermolecular hydrogen bonds into two distinct aggregates. Simple filaments with one monomer in the cross-section are formed at high temperature, although tubes with three bis-ureas in the cross section are formed at low temperature. These two aggregates self-assembled in a highly cooperative fashion and are in dynamic equilibrium with free monomers in solution. Kinetic studies were conducted on this system to determine different mechanistic purposes. By using chiral bis-urea monomers, supramolecular chirality was used to assess the exchange mechanism of material between the self-assembled tubes. The thermal transition between filaments and tubes is a reversible and very sharp process. A monomer with a precise moiety exhibits a strong hysteresis: the transition from tube-to-filament is fast, on the contrary the inverse transition is a very slow process. This particularly property was analysed towards differential scanning calorimetry and infrared spectroscopy. The chiral versions of this monomer induces a kinetic chiral self-sorting during the filament-to-tube transition. By mixing two competing chiral monomers, the resulting supramolecular chirality was a counter-intuitive combination of the homopolymers: a small amount of the "dominant" monomer is sufficient to "inverse" the orientation of the major (but "recessive") monomer in the mixed tubes.