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Daniel Taton - One of the best experts on this subject based on the ideXlab platform.
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Benzophenone-functionalized, starlilke Polystyrenes as organic supports for a tridentate bis(imino)pyridinyliron/trimethylaluminum catalytic system for ethylene polymerization
Journal of Polymer Science Part A: Polymer Chemistry, 2006Co-Authors: Cécile Bouilhac, Alain Deffieux, Henri Cramail, Eric Cloutet, Daniel TatonAbstract:Starlike Polystyrenes composed of a microgel core and arms terminated with benzophenone groups were used as organic supports for a tridentate bis(imino)-pyridinyliron catalyst for ethylene polymerization in the presence of trimethylaluminum as a cocatalyst. The microgels were synthesized by the atom transfer radical polymerization of styrene initiated by 4-(1-bromoethyl)-benzophenone, with divinyl-benzene as the crosslinker. The bromine polystyrene chain ends prevented the ethylene polymerization reaction and bad to be removed. This was readily achieved with Cu-0 together with dodecanethiol as a transfer agent. When used as supports in the presence of trimethylaluminum and 2,6-bis[1-2,6(diisopropylphenyl)imino]ethylpyridynyl iron, these bromine-free, functionalized. polystyrene stars enabled the production of polyethylene beads of a spherical morphology and high bulk density with a catalytic activity similar to that under homogeneous reaction conditions. Moreover, the molar mass distribution of the polyethylene was narrow, suggesting limited transfer to trimethylaluminum
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benzophenone functionalized starlike Polystyrenes as organic supports for a tridentate bis imino pyridinyliron trimethylaluminum catalytic system for ethylene polymerization
Journal of Polymer Science Part A, 2006Co-Authors: Cécile Bouilhac, Alain Deffieux, Henri Cramail, Eric Cloutet, Daniel TatonAbstract:Starlike Polystyrenes composed of a microgel core and arms terminated with benzophenone groups were used as organic supports for a tridentate bis(imino)pyridinyliron catalyst for ethylene polymerization in the presence of trimethylaluminum as a cocatalyst. The microgels were synthesized by the atom transfer radical polymerization of styrene initiated by 4-(1-bromoethyl)-benzophenone, with divinylbenzene as the crosslinker. The bromine polystyrene chain ends prevented the ethylene polymerization reaction and had to be removed. This was readily achieved with Cu0 together with dodecanethiol as a transfer agent. When used as supports in the presence of trimethylaluminum and 2,6-bis[1-2,6(diisopropylphenyl)imino]ethylpyridynyl iron, these bromine-free, functionalized polystyrene stars enabled the production of polyethylene beads of a spherical morphology and high bulk density with a catalytic activity similar to that under homogeneous reaction conditions. Moreover, the molar mass distribution of the polyethylene was narrow, suggesting limited transfer to trimethylaluminum. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6997–7007, 2006
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Synthesis of dendrimer-like polystyrene by atom transfer radical polymerization and investigation of their viscosity behavior
International Journal of Biological Macromolecules, 2005Co-Authors: Bénédicte Lepoittevin, Daniel Taton, Rachid Matmour, Raju Francis, Yves GnanouAbstract:The synthesis of dendrimer-like polystyrene (PS) of second and third generations by combination of atom transfer radical polymerization (ATRP) and chain end modifications is reported. Calixarene-based cores were used as initiators for ATRP of styrene yielding star polymers containing precisely 4, 6, or 8 arms. The latter were modified in two steps so as to generate PS stars carrying 8, 12, or 16 terminal bromoisobutyrate groups, respectively. These precursors served as multifunctional macroinitiators for the formation of the second generation of dendrimer-like PS. Reiteration of the aforementioned sequence of reactions allowed to derive dendrimer-like polystyrene of third generation that were constituted of 16, 24, or 32 outer arms, respectively. The chain end modification was monitored by H-1 NMR spectroscopy. The dendrimer-like PS were also characterized by size exclusion chromatography equipped with a multiangle laser light scattering detector (SEC/MALLS). The actual polymer architecture and the functionality of the stars were confirmed by analysis of the individual arms obtained upon hydrolysis of the ester links present at the core of the stars and at the branching points. The intrinsic viscosities of these dendrimer-like Polystyrenes are similar to those reported for regular dendrimers.
Alain Deffieux - One of the best experts on this subject based on the ideXlab platform.
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benzophenone functionalized starlike Polystyrenes as organic supports for a tridentate bis imino pyridinyliron trimethylaluminum catalytic system for ethylene polymerization
Journal of Polymer Science Part A, 2006Co-Authors: Cécile Bouilhac, Alain Deffieux, Henri Cramail, Eric Cloutet, Daniel TatonAbstract:Starlike Polystyrenes composed of a microgel core and arms terminated with benzophenone groups were used as organic supports for a tridentate bis(imino)pyridinyliron catalyst for ethylene polymerization in the presence of trimethylaluminum as a cocatalyst. The microgels were synthesized by the atom transfer radical polymerization of styrene initiated by 4-(1-bromoethyl)-benzophenone, with divinylbenzene as the crosslinker. The bromine polystyrene chain ends prevented the ethylene polymerization reaction and had to be removed. This was readily achieved with Cu0 together with dodecanethiol as a transfer agent. When used as supports in the presence of trimethylaluminum and 2,6-bis[1-2,6(diisopropylphenyl)imino]ethylpyridynyl iron, these bromine-free, functionalized polystyrene stars enabled the production of polyethylene beads of a spherical morphology and high bulk density with a catalytic activity similar to that under homogeneous reaction conditions. Moreover, the molar mass distribution of the polyethylene was narrow, suggesting limited transfer to trimethylaluminum. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6997–7007, 2006
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Benzophenone-functionalized, starlilke Polystyrenes as organic supports for a tridentate bis(imino)pyridinyliron/trimethylaluminum catalytic system for ethylene polymerization
Journal of Polymer Science Part A: Polymer Chemistry, 2006Co-Authors: Cécile Bouilhac, Alain Deffieux, Henri Cramail, Eric Cloutet, Daniel TatonAbstract:Starlike Polystyrenes composed of a microgel core and arms terminated with benzophenone groups were used as organic supports for a tridentate bis(imino)-pyridinyliron catalyst for ethylene polymerization in the presence of trimethylaluminum as a cocatalyst. The microgels were synthesized by the atom transfer radical polymerization of styrene initiated by 4-(1-bromoethyl)-benzophenone, with divinyl-benzene as the crosslinker. The bromine polystyrene chain ends prevented the ethylene polymerization reaction and bad to be removed. This was readily achieved with Cu-0 together with dodecanethiol as a transfer agent. When used as supports in the presence of trimethylaluminum and 2,6-bis[1-2,6(diisopropylphenyl)imino]ethylpyridynyl iron, these bromine-free, functionalized. polystyrene stars enabled the production of polyethylene beads of a spherical morphology and high bulk density with a catalytic activity similar to that under homogeneous reaction conditions. Moreover, the molar mass distribution of the polyethylene was narrow, suggesting limited transfer to trimethylaluminum
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α acetal ω bis hydroxymethyl heterodifunctional polystyrene synthesis characterization and investigation of intramolecular end to end ring closure
Macromolecules, 2001Co-Authors: Manuel Schappacher, Alain DeffieuxAbstract:A route to macrocyclic polystyrene of controlled dimensions based on a new ring closure process has been investigated. It involved the direct coupling of an α-acetal,ω-bis(hydroxymethyl) heterodifunctional linear polystyrene precursor previously prepared by living anionic polymerization. Cyclization was achieved under high dilution, by intramolecular condensation of the polymer ends in the presence of a mild acid as catalyst. Macrocyclic Polystyrenes were prepared directly in high yield (>90%) without any necessary fractionation step. The synthesis and structural characterization of both the linear α,ω-heterodifunctional precursors and the corresponding cyclized Polystyrenes, as well as a preliminary investigation of their stability and specific thermal properties, are reported.
Cécile Bouilhac - One of the best experts on this subject based on the ideXlab platform.
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Benzophenone-functionalized, starlilke Polystyrenes as organic supports for a tridentate bis(imino)pyridinyliron/trimethylaluminum catalytic system for ethylene polymerization
Journal of Polymer Science Part A: Polymer Chemistry, 2006Co-Authors: Cécile Bouilhac, Alain Deffieux, Henri Cramail, Eric Cloutet, Daniel TatonAbstract:Starlike Polystyrenes composed of a microgel core and arms terminated with benzophenone groups were used as organic supports for a tridentate bis(imino)-pyridinyliron catalyst for ethylene polymerization in the presence of trimethylaluminum as a cocatalyst. The microgels were synthesized by the atom transfer radical polymerization of styrene initiated by 4-(1-bromoethyl)-benzophenone, with divinyl-benzene as the crosslinker. The bromine polystyrene chain ends prevented the ethylene polymerization reaction and bad to be removed. This was readily achieved with Cu-0 together with dodecanethiol as a transfer agent. When used as supports in the presence of trimethylaluminum and 2,6-bis[1-2,6(diisopropylphenyl)imino]ethylpyridynyl iron, these bromine-free, functionalized. polystyrene stars enabled the production of polyethylene beads of a spherical morphology and high bulk density with a catalytic activity similar to that under homogeneous reaction conditions. Moreover, the molar mass distribution of the polyethylene was narrow, suggesting limited transfer to trimethylaluminum
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benzophenone functionalized starlike Polystyrenes as organic supports for a tridentate bis imino pyridinyliron trimethylaluminum catalytic system for ethylene polymerization
Journal of Polymer Science Part A, 2006Co-Authors: Cécile Bouilhac, Alain Deffieux, Henri Cramail, Eric Cloutet, Daniel TatonAbstract:Starlike Polystyrenes composed of a microgel core and arms terminated with benzophenone groups were used as organic supports for a tridentate bis(imino)pyridinyliron catalyst for ethylene polymerization in the presence of trimethylaluminum as a cocatalyst. The microgels were synthesized by the atom transfer radical polymerization of styrene initiated by 4-(1-bromoethyl)-benzophenone, with divinylbenzene as the crosslinker. The bromine polystyrene chain ends prevented the ethylene polymerization reaction and had to be removed. This was readily achieved with Cu0 together with dodecanethiol as a transfer agent. When used as supports in the presence of trimethylaluminum and 2,6-bis[1-2,6(diisopropylphenyl)imino]ethylpyridynyl iron, these bromine-free, functionalized polystyrene stars enabled the production of polyethylene beads of a spherical morphology and high bulk density with a catalytic activity similar to that under homogeneous reaction conditions. Moreover, the molar mass distribution of the polyethylene was narrow, suggesting limited transfer to trimethylaluminum. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6997–7007, 2006
Yves Gnanou - One of the best experts on this subject based on the ideXlab platform.
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Combination of an anionic terminator multifunctional initiator and divergent carbanionic polymerization: Application to the synthesis of dendrimer-like polymers and of asymmetric and miktoarm stars
Journal of the American Chemical Society, 2008Co-Authors: Rachid Matmour, Yves GnanouAbstract:A new and versatile synthetic strategy that provides access to precisely defined and totally soluble multicarbanionic initiators has been implemented to obtain by divergent growth dendrimer-like samples of polystyrene (PS) (up to the seventh generation) or polybutadiene (PB) (up to the third generation) and also asymmetric and miktoarm stars. This strategy rests on lithium-halide exchange reactions to generate multicarbanionic species and on the design of an original reagent that can concomitantly react with living carbanionic chains/arms to deactivate them and produce multicarbanionic sites after exchange of its bromides against lithium. This reagent, 4,4'-dibromodiphenylethylene (1), functions as a TERminating agent and a Multifunctional INItiator (TERMINI), according to a concept first proposed by Percec in another context. Upon using this anionic TERMINI in living carbanionic polymerization and repeating the two steps of chain end derivatization by 1 and divergent arm growth from the multifunctional sites generated, perfectly defined dendrimer-like polystyrene and polybutadiene could be obtained up to the seventh generation for the former and up to the third generation for the latter. Each step, i.e., chain end modification and arm growth, was carefully monitored, and the dendrimer-like samples of PS and PB were all characterized by size exclusion chromatography equipped with a multiangle laser light scattering detector (SEC/LS) and high-temperature size exclusion chromatography equipped with a viscometric detector (HT-SEC). The viscosity behavior of these dendrimer-like Polystyrenes-bell-shaped variation versus the number of generation-was found to be similar to that reported for regular dendrimers. This chemistry, namely this anionic TERMINI, was also exploited to derive three-arm asymmetric and miktoarm stars.
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Synthesis of dendrimer-like polystyrene by atom transfer radical polymerization and investigation of their viscosity behavior
International Journal of Biological Macromolecules, 2005Co-Authors: Bénédicte Lepoittevin, Daniel Taton, Rachid Matmour, Raju Francis, Yves GnanouAbstract:The synthesis of dendrimer-like polystyrene (PS) of second and third generations by combination of atom transfer radical polymerization (ATRP) and chain end modifications is reported. Calixarene-based cores were used as initiators for ATRP of styrene yielding star polymers containing precisely 4, 6, or 8 arms. The latter were modified in two steps so as to generate PS stars carrying 8, 12, or 16 terminal bromoisobutyrate groups, respectively. These precursors served as multifunctional macroinitiators for the formation of the second generation of dendrimer-like PS. Reiteration of the aforementioned sequence of reactions allowed to derive dendrimer-like polystyrene of third generation that were constituted of 16, 24, or 32 outer arms, respectively. The chain end modification was monitored by H-1 NMR spectroscopy. The dendrimer-like PS were also characterized by size exclusion chromatography equipped with a multiangle laser light scattering detector (SEC/MALLS). The actual polymer architecture and the functionality of the stars were confirmed by analysis of the individual arms obtained upon hydrolysis of the ester links present at the core of the stars and at the branching points. The intrinsic viscosities of these dendrimer-like Polystyrenes are similar to those reported for regular dendrimers.
Yushu Matsushita - One of the best experts on this subject based on the ideXlab platform.
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sans study on chain dimension of Polystyrenes diluted with low molecular weight homologues in semi dilute solutions
Polymer, 2013Co-Authors: Naoya Torikai, Naomi Takabayashi, Jiro Suzuki, Ichiro Noda, Yushu MatsushitaAbstract:Abstract Chain dimension of Polystyrenes diluted with low molecular-weight homologues in semi-dilute solutions was investigated, referring to the results for solutions in benzene and styrene monomer, and its concentration dependence was clarified by small-angle neutron scattering (SANS) with a “contrast-matching” method. The styrene monomer was found to act as a good solvent comparable to benzene. The polystyrene was confirmed to expand in the bulk “diluent” homologues having sufficiently low molecular-weights, and its concentration dependence of expansion factor, α, became weaker with increasing the degree of polymerization, NS, of the short “diluent” polymer. The critical NS value, NS,c, which is defined as the maximum value to give excluded volume effects, was much higher than the earlier theoretical prediction by de Gennes, i.e., N S , c ∼ N L 1 / 2 , where NL is the degree of polymerization of the long “solute” polymer. The power law exponent for NS-dependence of α seems to follow −1/16, rather than −1/8 predicted by the scaling, suggesting that screening blob size, ξ, can be scaled as ξ ∼ N S 1 / 2 , which is equivalent to the radius of gyration for the “diluent” polymers.
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precise synthesis and characterization of tadpole shaped Polystyrenes with high purity
Macromolecules, 2013Co-Authors: Yuya Doi, Atsushi Takano, Y Ohta, Masahide Nakamura, Yoshiaki Takahashi, Yushu MatsushitaAbstract:Tadpole-shaped Polystyrenes (PS) were successfully synthesized anionically by coupling reaction between ring polystyrene with two functional groups and living linear Polystyrenes. Crude coupling product was confirmed to include unreacted linear tail polymer and tadpole polymer having one tail (single-tail tadpole polymer) and two tails (twin-tail tadpole polymer) by SEC analysis. In order to isolate the tadpole polymers, interaction chromatography (IC) was conducted to remove the linear polymer from the crude product; subsequently, two kinds of tadpole polymers were carefully separated by SEC fractionation. It has been found by SEC-MALS that the absolute molecular weights of the two fractionated products agree well with the sums of the component ring and linear chains, which prove two tadpole polymers, i.e., single-tail and twin-tail, were obtained as designed. It was confirmed that the two tadpole polymers have high molecular weight (58k for ring and 67k for a tail), narrow molecular weight distribution ...
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the second virial coefficients of highly purified ring Polystyrenes in cyclohexane
Polymer, 2009Co-Authors: Atsushi Takano, Keisuke Masuoka, Y Ohta, Yuuki Kushida, Yushu MatsushitaAbstract:Abstract The second virial coefficients A 2 of ring Polystyrenes with high purity in cyclohexane were measured by light scattering in the temperature range 27.0–34.5 °C. The purity of four samples with M w of 16k, 42k, 110k and 570k was determined to be all over 96% by HPLC. It has been found that A 2 s of all the samples are definitely positive at the theta temperature of linear polystyrene, 34.5 °C, and the measured values for four samples converged to zero at 27.7 °C with decreasing temperature. This value is below the previously reported one, but it is quite consistent with the predicted value based on the topological repulsive interaction among the ring polymer molecules.
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preparation and characterization of cyclic Polystyrenes
Polymer Journal, 2005Co-Authors: Donghyun Cho, Keisuke Masuoka, Kazuhiro Koguchi, Takeshi Asari, Daisuke Kawaguchi, Atsushi Takano, Yushu MatsushitaAbstract:Macrocyclic Polystyrenes with various molecular weight were prepared by the reaction of linear polystyrene having two end vinyl groups and potassium naphthalenide as a coupling agent. Intermolecular side reactions produced higher molecular weight polycondensates and undesirable chain termination reactions also produced linear precursors in addition to the designed molecules. In order to isolate cyclic polymers from the ring closure reaction mixtures, preparative size exclusion chromatography (SEC) method was employed. The purity of SEC-fractionated cyclic Polystyrenes was rigorously examined by liquid chromatography at the critical condition (LCCC) and interaction chromatography (IC). After SEC-fractionation, we obtained large amount of highly pure cyclic polymers, though high molecular weight cyclic polymers contain very small amount of linear precursor (<5%). The purity and isotope effect on reversed-phase liquid chromatography (RPLC) were also rigorously investigated by preparing a deuterated cyclic polystyrene.