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Fanny Bonnet - One of the best experts on this subject based on the ideXlab platform.

  • bis phenolate amine supported lanthanide borohydride complexes for styrene and trans 1 4 isoprene co polymerisations
    Dalton Transactions, 2015
    Co-Authors: Fanny Bonnet, Marc Visseaux, Hellen E Dyer, Yassine El Kinani, Chjt Carin Dietz, Pascal Roussel, Marc Bria, Philippe Zinck, Philip Mountford
    Abstract:

    New bis(phenolate)amine-supported neodymium borohydride complexes and their previously reported samarium analogues were tested as catalysts for the polymerisation of styrene and isoprene. Reaction of Na2O2NL (L = py, OMe, NMe2) with Nd(BH4)3(THF)3 afforded the borohydride complexes Nd(O2NL)(BH4)(THF) (L = py (1-Nd), OMe (2-Nd), NMe2 (3-Nd)). Complex 1-Nd has shown a propensity to form phenolate-O-bridged dimer [Nd(μ-O2Npy)(BH4)]2 (1′-Nd) as previously observed with the samarium analogues Sm(O2NL)(BH4)(THF) (L = py or Pr). X-ray structures of 1′-Nd and 2-Nd were determined and are presented. The neodymium borohydride complexes 1-Nd to 3-Nd and their samarium analogues Sm(O2NL)(BH4)(THF)x (L = py (1-Sm), OMe (2-Sm), NMe2 (3-Sm), Pr (4-Sm)) were tested as catalysts for the polymerisation of isoprene and styrene in the presence of n-butylethylmagnesium (Mg(nBu)(Et)). All complexes were found to be active for the polymerisation of isoprene in these conditions, leading to polyisoprene up to 95.1% trans-1,4 stereoregular. They were also found to be active for the polymerisation of styrene leading to atactic polystyrene in all cases. Interestingly, samarium-based complexes were found to be more active than the neodymium ones toward this latter monomer, in sharp contrast to what is usually observed with rare earth borohydride complexes. The structure of both trans-Polyisoprenes and polystyrenes obtained were studied in detail by MALDI-ToF analysis in order to better understand the polymerisation mechanisms. The coordinative chain transfer polymerisation (CCTP) of both monomers was further conducted using Mg(nBu)(Et) as transfer agent. Finally, the statistical copolymerisation of isoprene and styrene was examined using these catalytic systems, leading to the formation of poly[(trans-1,4-isoprene)-co-styrene] with up to 39% of styrene moieties inserted in a highly trans-1,4-stereoregular polyisoprene.

  • highly trans stereospecific isoprene polymerization by neodymium borohydrido catalysts
    Macromolecules, 2005
    Co-Authors: Fanny Bonnet, Marc Visseaux, And Angela Pereira, Denise Barbierbaudry
    Abstract:

    Highly stereospecific polymerization of isoprene was achieved using borohydridoneodymium complexes. In combination with stoichiometric amounts of dialkylmagnesium, Nd(BH4)3(THF)3 (1) and Cp*‘Nd(BH4)2(THF)2 (2) (Cp*‘ = C5Me4nPr) afford very efficient catalysts. The activity reaches 37300 (g of polyisoprene/mol of Nd)/h. Half-lanthanidocene 2 gives rise to polyisoprene, 98.5% trans-regular, the highest content yet described for a homogeneous organometallic catalyst. NMR experiments argue for the formation of bimetallic Nd(μ-BH4)Mg active species.

  • Highly trans-stereospecific Isoprene Polymerization by Neodymium Borohydrido Catalysts
    Macromolecules, 2005
    Co-Authors: Fanny Bonnet, Marc Visseaux, Angela Pereira, Denise Barbier-baudry
    Abstract:

    Highly stereospecific polymerization of isoprene was achieved using borohydrido neodymium complexes. In combination with stoichiometric amounts of dialkylmagnesium, Nd(BH4)3(THF)3 (1) and Cp*'Nd(BH4)2(THF)2 (2) (Cp*' = C5Me4nPr) afford very efficient catalysts. Activity reaches 37300 g polyisoprene/mol Nd/h. Half-lanthanidocene 2 gives rise to polyisoprene 98.5 % trans-regular, the highest content yet described for a homogeneous organometallic catalyst. NMR experiments argue for the formation of bimetallic Nd(m-BH4)Mg active species.

  • diene polar monomer copolymers compatibilisers for polar non polar polymer blends a controlled block copolymerisation with a single site component samarocene initiator
    Macromolecular Chemistry and Physics, 2002
    Co-Authors: Denise Barbierbaudry, Fanny Bonnet, A Dormond, Eric Finot, Marc Visseaux
    Abstract:

    A well-controlled two-step process, the polymerisation of isoprene or isoprene/hex-1-ene copolymerisation followed by e-caprolactone polymerisation, affords trans-polyisoprene or (trans-polyisoprene/hex-1-ene copolymer)–poly(e-caprolactone) diblocks of various lengths. The single component initiator is an allylsamarocene compound. An atomic force microscopy study shows that these copolymers are efficient compatibilisers for poly(e-caprolactone) and polyisoprene blends. Poly(e-caprolactone) chain growth from Sm–polyisoprene chain.

Frederic Peruch - One of the best experts on this subject based on the ideXlab platform.

  • telechelic polybutadienes or Polyisoprenes precursors for recyclable elastomeric networks
    Macromolecular Rapid Communications, 2017
    Co-Authors: Pierre Berto, Stéphane Grelier, Frederic Peruch
    Abstract:

    (Bis)furan-telechelic, low-molar-mass polybutadienes and Polyisoprenes are synthesized by controlled degradation of high molar mass polymers and chain-end modifications yielding difunctional, trifunctional, or tetrafunctional polymers. Addition of a bismaleimide to the liquid-modified polymer leads to the formation of a thermoreversible elastomeric network based on the Diels–Alder chemistry for the trifunctional or tetrafunctional polymers, whereas only chain extension occurs for the bifunctional one. Dynamic mechanical analyses or tensile tests are performed on the networks and reveal a similar behavior for polyisoprene and polybutadiene with nevertheless quite different Young modulus or strain at break. The retro Diels–Alder reaction occurs upon heating, allowing the remolding of the used elastomer. The remolded network exhibits the same mechanical properties as the initial network, showing an efficient material recyclability.

  • Bio-inspired cationic polymerization of isoprene and analogues: state-of-the-art
    Polymer International, 2012
    Co-Authors: Samira Ouardad, Sergei V Kostjuk, Alain Deffieux, Marc-elias Bakleh, Francois Ganachaud, Judit E. Puskas, Frederic Peruch
    Abstract:

    Natural rubber (NR), which is polyisoprene about 100% 1,4-cis of high molar mass, > 10(6) g mol(-1), is mainly produced in southeast Asia and represents around 40%-45% of total worldwide elastomer consumption. Whereas more than 2500 plant species are able to produce polyisoprenoids, the only established commercial source of NR is Hevea braziliensis. NR presents high performance properties that are so far not matched by synthetic rubbers. As a consequence, NR is irreplaceable in many applications (aircraft tires, surgery gloves etc.). Nature and synthetic polymer chemists start from different substrates to synthesize Polyisoprenes, i.e. isopentenyl pyrophosphate (IPP), which is a universal building brick utilized by plants and animals, and isoprene monomer, respectively. Nevertheless, we proposed that the elementary processes involved in the biosynthesis of NR are very similar to those of cationic polymerization. In the course of a study on bio-inspired cationic polymerization of isoprene and IPP analogues, it appeared that cationic polymerization of isoprene proceeds readily and leads mainly to its 1,4-trans addition; such a process nevertheless remains difficult to control due to the occurrence of many side reactions (transfer, protic initiation, branching, cyclization). The present paper describes our understanding of the cationic polymerization of isoprene and its analogues catalyzed by different Lewis acids, in solution and aqueous dispersions.

  • bio inspired cationic polymerization of isoprene and analogues state of the art
    Polymer International, 2012
    Co-Authors: Samira Ouardad, Sergei V Kostjuk, Alain Deffieux, Marc-elias Bakleh, Francois Ganachaud, Judit E. Puskas, Frederic Peruch
    Abstract:

    Natural rubber (NR), which is polyisoprene about 100% 1,4-cis of high molar mass, > 106 g mol−1, is mainly produced in southeast Asia and represents around 40%–45% of total worldwide elastomer consumption. Whereas more than 2500 plant species are able to produce polyisoprenoids, the only established commercial source of NR is Hevea braziliensis. NR presents high performance properties that are so far not matched by synthetic rubbers. As a consequence, NR is irreplaceable in many applications (aircraft tires, surgery gloves etc.). Nature and synthetic polymer chemists start from different substrates to synthesize Polyisoprenes, i.e. isopentenyl pyrophosphate (IPP), which is a universal building brick utilized by plants and animals, and isoprene monomer, respectively. Nevertheless, we proposed that the elementary processes involved in the biosynthesis of NR are very similar to those of cationic polymerization. In the course of a study on bio-inspired cationic polymerization of isoprene and IPP analogues, it appeared that cationic polymerization of isoprene proceeds readily and leads mainly to its 1,4-trans addition; such a process nevertheless remains difficult to control due to the occurrence of many side reactions (transfer, protic initiation, branching, cyclization). The present paper describes our understanding of the cationic polymerization of isoprene and its analogues catalyzed by different Lewis acids, in solution and aqueous dispersions. Copyright © 2011 Society of Chemical Industry

Marc Visseaux - One of the best experts on this subject based on the ideXlab platform.

  • bis phenolate amine supported lanthanide borohydride complexes for styrene and trans 1 4 isoprene co polymerisations
    Dalton Transactions, 2015
    Co-Authors: Fanny Bonnet, Marc Visseaux, Hellen E Dyer, Yassine El Kinani, Chjt Carin Dietz, Pascal Roussel, Marc Bria, Philippe Zinck, Philip Mountford
    Abstract:

    New bis(phenolate)amine-supported neodymium borohydride complexes and their previously reported samarium analogues were tested as catalysts for the polymerisation of styrene and isoprene. Reaction of Na2O2NL (L = py, OMe, NMe2) with Nd(BH4)3(THF)3 afforded the borohydride complexes Nd(O2NL)(BH4)(THF) (L = py (1-Nd), OMe (2-Nd), NMe2 (3-Nd)). Complex 1-Nd has shown a propensity to form phenolate-O-bridged dimer [Nd(μ-O2Npy)(BH4)]2 (1′-Nd) as previously observed with the samarium analogues Sm(O2NL)(BH4)(THF) (L = py or Pr). X-ray structures of 1′-Nd and 2-Nd were determined and are presented. The neodymium borohydride complexes 1-Nd to 3-Nd and their samarium analogues Sm(O2NL)(BH4)(THF)x (L = py (1-Sm), OMe (2-Sm), NMe2 (3-Sm), Pr (4-Sm)) were tested as catalysts for the polymerisation of isoprene and styrene in the presence of n-butylethylmagnesium (Mg(nBu)(Et)). All complexes were found to be active for the polymerisation of isoprene in these conditions, leading to polyisoprene up to 95.1% trans-1,4 stereoregular. They were also found to be active for the polymerisation of styrene leading to atactic polystyrene in all cases. Interestingly, samarium-based complexes were found to be more active than the neodymium ones toward this latter monomer, in sharp contrast to what is usually observed with rare earth borohydride complexes. The structure of both trans-Polyisoprenes and polystyrenes obtained were studied in detail by MALDI-ToF analysis in order to better understand the polymerisation mechanisms. The coordinative chain transfer polymerisation (CCTP) of both monomers was further conducted using Mg(nBu)(Et) as transfer agent. Finally, the statistical copolymerisation of isoprene and styrene was examined using these catalytic systems, leading to the formation of poly[(trans-1,4-isoprene)-co-styrene] with up to 39% of styrene moieties inserted in a highly trans-1,4-stereoregular polyisoprene.

  • highly trans stereospecific isoprene polymerization by neodymium borohydrido catalysts
    Macromolecules, 2005
    Co-Authors: Fanny Bonnet, Marc Visseaux, And Angela Pereira, Denise Barbierbaudry
    Abstract:

    Highly stereospecific polymerization of isoprene was achieved using borohydridoneodymium complexes. In combination with stoichiometric amounts of dialkylmagnesium, Nd(BH4)3(THF)3 (1) and Cp*‘Nd(BH4)2(THF)2 (2) (Cp*‘ = C5Me4nPr) afford very efficient catalysts. The activity reaches 37300 (g of polyisoprene/mol of Nd)/h. Half-lanthanidocene 2 gives rise to polyisoprene, 98.5% trans-regular, the highest content yet described for a homogeneous organometallic catalyst. NMR experiments argue for the formation of bimetallic Nd(μ-BH4)Mg active species.

  • Highly trans-stereospecific Isoprene Polymerization by Neodymium Borohydrido Catalysts
    Macromolecules, 2005
    Co-Authors: Fanny Bonnet, Marc Visseaux, Angela Pereira, Denise Barbier-baudry
    Abstract:

    Highly stereospecific polymerization of isoprene was achieved using borohydrido neodymium complexes. In combination with stoichiometric amounts of dialkylmagnesium, Nd(BH4)3(THF)3 (1) and Cp*'Nd(BH4)2(THF)2 (2) (Cp*' = C5Me4nPr) afford very efficient catalysts. Activity reaches 37300 g polyisoprene/mol Nd/h. Half-lanthanidocene 2 gives rise to polyisoprene 98.5 % trans-regular, the highest content yet described for a homogeneous organometallic catalyst. NMR experiments argue for the formation of bimetallic Nd(m-BH4)Mg active species.

  • diene polar monomer copolymers compatibilisers for polar non polar polymer blends a controlled block copolymerisation with a single site component samarocene initiator
    Macromolecular Chemistry and Physics, 2002
    Co-Authors: Denise Barbierbaudry, Fanny Bonnet, A Dormond, Eric Finot, Marc Visseaux
    Abstract:

    A well-controlled two-step process, the polymerisation of isoprene or isoprene/hex-1-ene copolymerisation followed by e-caprolactone polymerisation, affords trans-polyisoprene or (trans-polyisoprene/hex-1-ene copolymer)–poly(e-caprolactone) diblocks of various lengths. The single component initiator is an allylsamarocene compound. An atomic force microscopy study shows that these copolymers are efficient compatibilisers for poly(e-caprolactone) and polyisoprene blends. Poly(e-caprolactone) chain growth from Sm–polyisoprene chain.

Ouardad Samira - One of the best experts on this subject based on the ideXlab platform.

  • Metathetic degradation of trans-1,4-polyisoprene with ruthenium catalysts
    'Elsevier BV', 2014
    Co-Authors: Ouardad Samira, Peruch Frédéric
    Abstract:

    Degradation study of trans-1,4-polyisoprene (trans-1,4-PI), that can be produced by the nature, was performed using first and second generation Grubbs and Hoveyda Grubbs catalysts with olefins (ethylene or 1-octene) as transfer agents in toluene at 60 C. While first generation Grubbs catalyst afforded low degradation, highlighting the presence of catalyst decomposition and/or inter-chain cross-metathesis reactions, an almost complete metathetic degradation could be reached using the second generation Grubbs catalyst in few minutes. Nevertheless, the synthesis of well-defined Polyisoprenes with a targeted molar mass revealed to be difficult with Grubbs catalysts. On the contrary, Hoveyda Grubbs catalysts were found to be more efficient to control the degradation of trans-1,4-PI. Indeed, regioselective degradation afforded pure trans-1,4-PI with a range of molar mass from 50 000 g/mol to 10 000 g/mol. However, Polyisoprenes of lower molar masses (M-n < 10 000 g/mol) contained some cis units, highlighting the presence of isomerization reactions, which could be due to the catalyst decomposition into hydride specie and/or pi-allyl metal hydrid

  • Towards a bio-inspired synthesis of polyterpenes and biorubber homologues by cationic polymerization and chemical modification
    2011
    Co-Authors: Ouardad Samira
    Abstract:

    Cette thèse a pour objectif de développer une nouvelle approche bio-inspirée des processus de polymérisation conduisant à la formation de polyterpènes et ultérieurement du caoutchouc naturel, un polyisoprène de structure purement 1,4-cis de forte masse molaire dont les propriétés sont encore inégalées par ses homologues synthétiques. Pour cette raison la production mondiale de caoutchouc naturel demeure stratégique et est toujours proche de 10 millions de tonnes, soit environ 45% de la demande mondiale annuelle en élastomères. Alors que les voies de synthèse développées jusqu’à présent pour accéder à des homologues du caoutchouc naturel sont basées sur la polymérisation par voie anionique ou par coordination de l’isoprène,l’approche suivie par la nature pour synthétiser les polyterpènes est basée sur la polymérisation à caractère cationique d’un autre monomère, le pyrophosphate d’isopentényle (IPP) qui est la brique de construction universelle de la famille des terpènes. Le projet a pour objet de tenter de reproduire au plus près le procédé naturel et d’utiliser, d’une part, la voie cationique pour polymériser des modèles de l’IPP et l’isoprène en utilisant des homologues du pyrophosphate dediméthylallyle (DMAPP, amorceur employé par la nature) comme amorceurs et des acides de Lewis pour mimer les cations divalents (Zn2+, Mg2+ or Mn2+) qui assistent les enzymes au cours des étapes d’ionisation et d’activation mises en jeu au cours de la biosynthèse, afin d’accéder à des polyterpènes approchant la structure des produits naturels. Contrairement à la nature, nous avons obtenus des oligomères de structure 1,4-trans avec de plus, de nombreuses structures cyclisées. D’autre part, nous avons également cherché à améliorer les propriétés d’un polyisoprène 1,4-cis obtenu par polymérisation anionique afin d’approcher celles du caoutchouc naturel. Nous avons développé une fonctionnalisation des chaines de polyisoprène 1,4-cis permettant d’ancrer des groupements urées susceptibles d’établir un réseau physique de liaisons hydrogènes. Nous avons montré que les polyisoprènes modifiés possèdent des propriétés viscoélastiques comparables à celles du caoutchouc naturel non vulcanisé obtenu par coagulation du latex.Although synthetic rubbers, including high cis-content polyisoprene (PIP), are used in a broad range ofapplications, they are far from achieving the performances of natural rubber (NR), a 100% 1,4-cis polyisoprenewith very high molar mass. Therefore, NR produced exclusively by hevea (whereas more than 2,500 plant species are known to produce polyterpene-based polymers) is still dominant in many engineering applications since its exceptional properties grants this polymer a strategic resource material which holds a significant marketshare (about 45%).. The only alternative plant species under cultivation, Parthenium argentatum, also calledguayule, produces a latex yielding rubber with properties close to those of hevea rubber, and marketed as “non allergenic natural rubber” but with a higher cost complex extraction processes The NR biosynthesis process isdescribed as a polymerization process involving a series of enzymatic reactions using isopentenyl pyrophosphate(IPP) as elementary building brick. Besides, synthetic PIPs with high cis-content were already produced fromisoprene monomer by Ziegler-Natta, lanthanide-based or anionic-type polymerizations. Currently, no syntheticPIPs mimics the performance of NR, maybe because 100% 1,4-cis PIP could so far not been produced synthetically. A close inspection of the NR biosynthesis process led us to postulate that this latter is consistent with a transferless, stereospecific carbocationic-type polymerization mechanism. We then propose to develop this new bio-inspired cationic-like polymerization approach with the aim to produce polyterpenes and then NR homologues of tailored molar mass and microstructure that could exhibit properties close to natural polyterpenes by using IPP homologues and isoprene as monomers, DMAPP homologues asinitiators and Lewis acids to mimick the divalent cations (Zn2+, Mg2+ or Mn2+) that assist the enzymes during the initiation end activation steps. For the cationic polymerization of isoprene, oligomers with 1,4-trans and cyclized structures were obtained. We also develop new routes to modify Polyisoprenes obtained by anionic polymerization in order to establish hydrogen interaction. To this end, different urea groups were grafted and the modified polyisoprene exhibite delastomeric properties close to the one of a non-vulcanized NR obtained by latex coagulatio

  • Approches bio-inspirées du caoutchouc naturel par polymérisation cationique et modification chimique
    2011
    Co-Authors: Ouardad Samira, Deffieux Alain, Peruch Frédéric
    Abstract:

    Cette thèse a pour objectif de développer une nouvelle approche bio-inspirée des processus de polymérisation conduisant à la formation de polyterpènes et ultérieurement du caoutchouc naturel, un polyisoprène de structure purement 1,4-cis de forte masse molaire dont les propriétés sont encore inégalées par ses homologues synthétiques. Pour cette raison la production mondiale de caoutchouc naturel demeure stratégique et est toujours proche de 10 millions de tonnes, soit environ 45% de la demande mondiale annuelle en élastomères. Alors que les voies de synthèse développées jusqu à présent pour accéder à des homologues du caoutchouc naturel sont basées sur la polymérisation par voie anionique ou par coordination de l isoprène,l approche suivie par la nature pour synthétiser les polyterpènes est basée sur la polymérisation à caractère cationique d un autre monomère, le pyrophosphate d isopentényle (IPP) qui est la brique de construction universelle de la famille des terpènes. Le projet a pour objet de tenter de reproduire au plus près le procédé naturel et d utiliser, d une part, la voie cationique pour polymériser des modèles de l IPP et l isoprène en utilisant des homologues du pyrophosphate dediméthylallyle (DMAPP, amorceur employé par la nature) comme amorceurs et des acides de Lewis pour mimer les cations divalents (Zn2+, Mg2+ or Mn2+) qui assistent les enzymes au cours des étapes d ionisation et d activation mises en jeu au cours de la biosynthèse, afin d accéder à des polyterpènes approchant la structure des produits naturels. Contrairement à la nature, nous avons obtenus des oligomères de structure 1,4-trans avec de plus, de nombreuses structures cyclisées. D autre part, nous avons également cherché à améliorer les propriétés d un polyisoprène 1,4-cis obtenu par polymérisation anionique afin d approcher celles du caoutchouc naturel. Nous avons développé une fonctionnalisation des chaines de polyisoprène 1,4-cis permettant d ancrer des groupements urées susceptibles d établir un réseau physique de liaisons hydrogènes. Nous avons montré que les polyisoprènes modifiés possèdent des propriétés viscoélastiques comparables à celles du caoutchouc naturel non vulcanisé obtenu par coagulation du latex.Although synthetic rubbers, including high cis-content polyisoprene (PIP), are used in a broad range ofapplications, they are far from achieving the performances of natural rubber (NR), a 100% 1,4-cis polyisoprenewith very high molar mass. Therefore, NR produced exclusively by hevea (whereas more than 2,500 plant species are known to produce polyterpene-based polymers) is still dominant in many engineering applications since its exceptional properties grants this polymer a strategic resource material which holds a significant marketshare (about 45%).. The only alternative plant species under cultivation, Parthenium argentatum, also calledguayule, produces a latex yielding rubber with properties close to those of hevea rubber, and marketed as non allergenic natural rubber but with a higher cost complex extraction processes The NR biosynthesis process isdescribed as a polymerization process involving a series of enzymatic reactions using isopentenyl pyrophosphate(IPP) as elementary building brick. Besides, synthetic PIPs with high cis-content were already produced fromisoprene monomer by Ziegler-Natta, lanthanide-based or anionic-type polymerizations. Currently, no syntheticPIPs mimics the performance of NR, maybe because 100% 1,4-cis PIP could so far not been produced synthetically. A close inspection of the NR biosynthesis process led us to postulate that this latter is consistent with a transferless, stereospecific carbocationic-type polymerization mechanism. We then propose to develop this new bio-inspired cationic-like polymerization approach with the aim to produce polyterpenes and then NR homologues of tailored molar mass and microstructure that could exhibit properties close to natural polyterpenes by using IPP homologues and isoprene as monomers, DMAPP homologues asinitiators and Lewis acids to mimick the divalent cations (Zn2+, Mg2+ or Mn2+) that assist the enzymes during the initiation end activation steps. For the cationic polymerization of isoprene, oligomers with 1,4-trans and cyclized structures were obtained. We also develop new routes to modify Polyisoprenes obtained by anionic polymerization in order to establish hydrogen interaction. To this end, different urea groups were grafted and the modified polyisoprene exhibite delastomeric properties close to the one of a non-vulcanized NR obtained by latex coagulationBORDEAUX1-Bib.electronique (335229901) / SudocSudocFranceF

  • Carbocationic Polymerization of Isoprene Co-initiated by B(C6F5)(3): An Alternative Route toward Natural Rubber Polymer Analogues?
    'American Chemical Society (ACS)', 2011
    Co-Authors: Kostjuk Sergei, Ouardad Samira, Deffieux Alain, Peruch Frédéric, Absalon Christelle, Puskas, Judit E., Ganachaud Francois
    Abstract:

    The cationic polymerization of isoprene using the 1-(4-methoxyphenyl)ethanol (1)/B(C6F5)(3) initiating system in solution (dichloromethane or alpha,alpha,alpha-trifluorotoluene) and in aqueous media. (suspension, dispersion, or emulsion) is reported. In organic solvents the reaction proceeded by controlled initiation via 1, followed by irreversible termination, thus affording polymers with a number-average molar mass M-n = 70%) in the polymer backbone. In particular, using alpha,alpha,alpha-trifluorotoluene as polymerization solvent in place of dichloromethane promoted the synthesis of polyisoprene chains with M-w/M-n similar to 1.4 and larger content of intact double bonds (up to 88%). In the absence of 1, Polyisoprenes with fairly high molar mass (M-n up to 18 000 g mol(-1)) and M-w/M-n < 24 were synthesized through adventitious water/B(C6F5)(3)-initiated cationic polymerization of isoprene. In aqueous media, the cationic polymerization of isoprene with 1/B(C6F5)(3) proceeded without any side reactions (cyclization, branching). However, aqueous conditions afforded only moderate yield (up to 60% monomer conversion) and Polyisoprenes with low M-n (

  • Carbocationic Polymerization of Isoprene Co-initiated by B (C6f5) 3: an Alternative Route Toward Natural Rubber Polymer Analogues?
    'American Chemical Society (ACS)', 2011
    Co-Authors: Kostjuk Sergei, Ouardad Samira, Deffieux Alain, Peruch Frédéric, Absalon Christelle, Puskas Judit, Ganachaud Francois
    Abstract:

    The cationic polymerization of isoprene using the 1-(4-methoxyphenyl)ethanol (1)/B(C6F5)3 initiating system in solution (dichloromethane or α,α,α-trifluorotoluene) and in aqueous media (suspension, dispersion, or emulsion) is reported. In organic solvents the reaction proceeded by controlled initiation via 1, followed by irreversible termination, thus affording polymers with a number-average molar mass Mn ≤ 5000 g mol−1 and a molar mass distribution or MMD (Mw/Mn ≤ 2.5) and rather high content of intact double bonds (≥70%) in the polymer backbone. In particular, using α,α,α-trifluorotoluene as polymerization solvent in place of dichloromethane promoted the synthesis of polyisoprene chains with Mw/Mn ∼ 1.4 and larger content of intact double bonds (up to 88%). In the absence of 1, Polyisoprenes with fairly high molar mass (Mn up to 18 000 g mol−1) and Mw/Mn \u3c 2.4 were synthesized through adventitious water/B(C6F5)3-initiated cationic polymerization of isoprene. In aqueous media, the cationic polymerization of isoprene with 1/B(C6F5)3 proceeded without any side reactions (cyclization, branching). However, aqueous conditions afforded only moderate yield (up to 60% monomer conversion) and Polyisoprenes with low Mn (≤1200 g mol−1) and Mw/Mn ≤ 1.7 were obtained. By comparing different characterization data (NMR, mass spectrometry), it was demonstrated that under appropriate conditions (in organic solvents at −30 °C or in aqueous media) Polyisoprenes carrying the initiator fragment from 1 at the α-end and an olefinic terminal group can be produced almost exclusively in a trans-1,4 configuration (92−96.5%)

Heurtefeu Bertrand - One of the best experts on this subject based on the ideXlab platform.

  • Supports organiques à base de polyisoprène pour la catalyse de polymérisation de l’éthylène
    2010
    Co-Authors: Heurtefeu Bertrand
    Abstract:

    Les travaux décrits dans ce manuscrit ont trait à l’élaboration de supports organiques fonctionnels à base de polyisoprène pour la catalyse de polymérisation de l’éthylène par les métallocène et post-métallocène. Une série de polyisoprènes ω-OH et de copolymères à blocs de type polyisoprène-b-poly(méthacrylate de méthyle) et polyisoprène-b-poly(oxyde d’éthylène) de masse molaire variable a été réalisée par polymérisation anionique vivante. L’auto-assemblage dans l’heptane de ces (co)polymères conduit à la formation d’agrégats micellaires stables qui permettent l’immobilisation des systèmes catalytiques via des interactions créées entre le bloc polaire du support et l’activateur aluminique, le plus souvent le méthylaluminoxane. La polymérisation de l’éthylène en présence de ces supports organiques conduit, sans diminution d’activité catalytique, à la formation de particules de polyéthylène de taille micrométrique. Selon la même méthodologie, des polyisoprènes portant à leur extrémité une fonction borate ont été synthétisés et avantageusement utilisés comme supports activateurs de métallocènes pré-alkylés. Dans ce cas, des particules de polyéthylène de taille millimétrique ont pu être obtenues.The work described in this manuscript relates the development of organic functional supports based on polyisoprene for the catalysis of ethylene polymerization by metallocenes and post-metallocenes. Polyisoprenes ω-OH and block copolymers [polyisoprene-b-poly(methyl methacrylate) and polyisoprene-b-poly(ethylene oxide)] with different molecular weights were synthesized by living anionic polymerization. Self-assembly in heptane of (co)polymers leads to the formation of stable micellar aggregates allowing the immobilization of catalytic systems created thanks to interactions between the polar block of the support and the aluminic activator, the most often methylaluminoxane. The ethylene polymerization in the presence of organic support drives, without loss of catalytic activity, to the formation of polyethylene particles of micrometer size. Using the same methodology, Polyisoprenes bearing at their ends a borate function have been synthesized and advantageously used as supports activators of pre-alkylated metallocenes. In this case, polyethylene particles with a millimeter size have been obtained

  • Supports organiques à base de polyisoprène pour la catalyse de polymérisation de l'éthylène
    2010
    Co-Authors: Heurtefeu Bertrand, Cramail Henri
    Abstract:

    Les travaux décrits dans ce manuscrit ont trait à l élaboration de supports organiques fonctionnels à base de polyisoprène pour la catalyse de polymérisation de l éthylène par les métallocène et post-métallocène. Une série de polyisoprènes -OH et de copolymères à blocs de type polyisoprène-b-poly(méthacrylate de méthyle) et polyisoprène-b-poly(oxyde d éthylène) de masse molaire variable a été réalisée par polymérisation anionique vivante. L auto-assemblage dans l heptane de ces (co)polymères conduit à la formation d agrégats micellaires stables qui permettent l immobilisation des systèmes catalytiques via des interactions créées entre le bloc polaire du support et l activateur aluminique, le plus souvent le méthylaluminoxane. La polymérisation de l éthylène en présence de ces supports organiques conduit, sans diminution d activité catalytique, à la formation de particules de polyéthylène de taille micrométrique. Selon la même méthodologie, des polyisoprènes portant à leur extrémité une fonction borate ont été synthétisés et avantageusement utilisés comme supports activateurs de métallocènes pré-alkylés. Dans ce cas, des particules de polyéthylène de taille millimétrique ont pu être obtenues.The work described in this manuscript relates the development of organic functional supports based on polyisoprene for the catalysis of ethylene polymerization by metallocenes and post-metallocenes. Polyisoprenes -OH and block copolymers [polyisoprene-b-poly(methyl methacrylate) and polyisoprene-b-poly(ethylene oxide)] with different molecular weights were synthesized by living anionic polymerization. Self-assembly in heptane of (co)polymers leads to the formation of stable micellar aggregates allowing the immobilization of catalytic systems created thanks to interactions between the polar block of the support and the aluminic activator, the most often methylaluminoxane. The ethylene polymerization in the presence of organic support drives, without loss of catalytic activity, to the formation of polyethylene particles of micrometer size. Using the same methodology, Polyisoprenes bearing at their ends a borate function have been synthesized and advantageously used as supports activators of pre-alkylated metallocenes. In this case, polyethylene particles with a millimeter size have been obtained.BORDEAUX1-Bib.electronique (335229901) / SudocSudocFranceF