Hutchinson Center de Recherche

Châlette-sur-Loing, France

Hutchinson Center de Recherche

Châlette-sur-Loing, France
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Pire M.,CNRS Laboratory for Soft Matter & Chemistry | Lorthioir C.,CNRS East Paris Institute of Chemistry and Materials Science | Oikonomou E.K.,CNRS Laboratory for Soft Matter & Chemistry | Norvez S.,CNRS Laboratory for Soft Matter & Chemistry | And 3 more authors.
Polymer Chemistry | Year: 2012

The crosslinking of epoxidized natural rubber with dodecanedioic acid and the mechanism of its acceleration by 1,2-dimethylimidazole (DMI) are investigated using nuclear magnetic resonance spectroscopy. Solid-state NMR experiments ( 1H, 1H → 13C cross-polarization and 13C direct polarization) are used to analyse crosslinked samples, whereas 13C solution NMR provides information about liquid epoxidized rubber species. 13C solid-state NMR demonstrates the ester nature of the crosslinks, and confirms that DMI acts through the formation of imidazolium dicarboxylate species, well dispersed in the elastomeric matrix. After synthesis of a low molecular weight epoxidized rubber and subsequent reaction with a monofunctional carboxylic acid in the presence of DMI, a solution NMR study reveals that the imidazolium dicarboxylate would react preferentially at the less substituted side of the epoxy site. © 2012 The Royal Society of Chemistry.


Pire M.,CNRS Laboratory for Soft Matter & Chemistry | Norvez S.,CNRS Laboratory for Soft Matter & Chemistry | Iliopoulos I.,CNRS Laboratory for Soft Matter & Chemistry | Le Rossignol B.,Hutchinson Center de Recherche | Leibler L.,CNRS Laboratory for Soft Matter & Chemistry
Polymer | Year: 2011

The crosslinking of epoxidized natural rubber (ENR) with dodecanedioic acid was tremendously accelerated in presence of 1,2-dimethylimidazole (DMI). The curing reaction of ENR containing 10 or 25 mol % epoxide groups was followed by rheology at 180 °C or 160 °C and the mechanical properties of the cured materials were examined by stress-strain experiments. An equimolar amount of accelerator and carboxylic functions was required to reach optimum tensile properties. Among a variety of usual accelerators, DMI was found the only one efficient, which was associated to the formation of reactive imidazolium carboxylates. The presence of these intermediates was supported by DSC experiments. Instead of a catalytic mechanism, the activation of the crosslinking agent is enabled by the synergetic association of DMI and diacid forming a soluble species in the rubber matrix. This simple system thus enables the efficient crosslinking of functionalized natural rubber without the use of sulphur or peroxides. © 2011 Elsevier Ltd. All rights reserved.


Froidevaux V.,Charles Gerhardt Institute | Borne M.,Charles Gerhardt Institute | Laborbe E.,Hutchinson Center de Recherche | Auvergne R.,Charles Gerhardt Institute | And 2 more authors.
RSC Advances | Year: 2015

The Diels-Alder reaction leads to a mixture of two diastereomers, one called endo and the other one exo. The cyclo-reversion temperature of the first one is lower than the exo adduct and the ratio between endo and exo adducts varies according to the substituents of the Diels-Alder partners and experimental parameters. Therefore, the influence of some reaction parameters such as the substituents of furan and maleimide derivatives, the reaction temperature and the presence of a nucleophile on the endo/exo Diels-Alder ratio and/or the retro-Diels-Alder reaction have been studied. For instance, furan and maleimide derivatives with electron withdrawing substituents induced the creation of the endo adduct preferentially. Also the presence of a far electron withdrawing substituent on furan and/or an electron attracting mesomeric substituent on maleimide resulted in a faster reversibility of the endo adduct. Finally, a high temperature and the presence of a nucleophile (thiol) also induced faster retro-Diels-Alder kinetics. Moreover, it was proved that isomerization from the endo to the exo diastereomer is preceded by a retro-Diels-Alder reaction of the endo adduct. The presence of a nucleophile in the mixture confirmed this result. This study allowed the highlighting of different parameters of the Diels-Alder reaction to obtain as much endo adduct as possible, and a fast and/or full retro-Diels-Alder reaction of this adduct. © The Royal Society of Chemistry 2015.


Froidevaux V.,Charles Gerhardt Institute | Negrell C.,Charles Gerhardt Institute | Laborbe E.,Hutchinson Center de Recherche | Auvergne R.,Charles Gerhardt Institute | Boutevin B.,Charles Gerhardt Institute
European Polymer Journal | Year: 2015

Abstract The aim of this study was to prepare new responsive polymers using an original thermal cross-linking reaction. The retroDiels-Alder reaction coupled, in situ, to a Michael addition allows the synthesis of materials with tailored properties. The syntheses of three different maleimides, one solid and two liquids, from Jeffamines® are presented. These maleimides have been blocked using Diels-Alder reaction and the concept of unprotection has been tested and proven by 1H NMR. Versatile polythiols (n ≥ 2) have been used as reactants in the Thia-Michael addition of free or blocked maleimides. Twelve materials have been synthesized, six with free maleimides and six with blocked maleimides, and the efficiencies of various formulations were examined only few seconds (<120 s) are necessary at room temperature (20-25 °C) with free maleimides to obtain a cross-linked material. On the contrary when the maleimide is blocked the stability at room temperature increases up to seven days and the cross-linking reaction only occurs by curing at 110 °C. The cross-linked materials have glass transition temperatures ranging from -50 °C to -7 °C and very good thermal stabilities (up to 350 °C). © 2015 Elsevier Ltd.


Pire M.,CNRS Laboratory for Soft Matter & Chemistry | Norvez S.,CNRS Laboratory for Soft Matter & Chemistry | Iliopoulos I.,CNRS Laboratory for Soft Matter & Chemistry | Le Rossignol B.,Hutchinson Center de Recherche | Leibler L.,CNRS Laboratory for Soft Matter & Chemistry
Composite Interfaces | Year: 2014

The work focuses on crosslinking epoxidised natural rubber by dicarboxylic acids which react with the epoxy sites along the chain. The crosslinking reaction at 180 °C is followed in a rheometer, and the cured materials are characterised by stress-strain experiments. The cure process is tremendously accelerated (from 3 h to 20 min) in the presence of an equimolar amount of 1,2-dimethylimidazole. Thermal stability and fatigue life experiments were carried out on samples charged with carbon black and antioxidants. The results are found in between the ones obtained with standard sulphur or peroxide crosslinked samples. © 2013 Taylor & Francis.


Stricher A.,CNRS Laboratory for Polymer Materials Engineering | Stricher A.,University of Lyon | Picard L.,Hutchinson Center de Recherche | Gabrielle B.,Hutchinson Center de Recherche | And 3 more authors.
Polymer International | Year: 2016

This paper is devoted to the characterization and processing of high molar mass vinyl-bearing polysiloxanes in high consistency silicone rubber (HCR) formulations. The molar masses of five different polydimethylsiloxane gums, bearing vinyl groups at the ends and along their chains, were evaluated by size exclusion chromatography and rheometry. 29Si and 1H NMR spectroscopy allowed the precise determination of the vinyl content and of the distribution in the different polymers. Typical HCRs formulated from these gums were heat-cured to process silicone rubber materials that were then tested mechanically. The macromolecular properties were correlated to the final material network structure. The amount of reactive vinyl moieties, rather than their distribution along or at the end of chains, is a key parameter to tailor the material mechanical properties. © 2016 Society of Chemical Industry.

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