The Experts below are selected from a list of 30 Experts worldwide ranked by ideXlab platform
Takeshi Fukuda - One of the best experts on this subject based on the ideXlab platform.
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Rate retardation in reversible addition fragmentation chain transfer raft polymerization further evidence for cross Termination producing 3 arm star chain
Macromolecules, 2004Co-Authors: Yungwan Kwak, And Atsushi Goto, Takeshi FukudaAbstract:New pieces of experimental evidence were presented showing that the Rate retardation in the polymerization of styrene with polystyryl dithiobenzoate (PSt-SCSPh) at 60 °C is caused by the irreversible cross-Termination between the polystyryl radical (PSt•) and the intermediate radical produced by the addition of PSt• to PSt-SCSPh. The polymerization Rate Rp decreased with an increase of [PSt-SCSPh] such that a plot of 1/Rp2 vs [PSt-SCSPh] was linear, as the irreversible cross-Termination mechanism demands. The cross-Termination Rate Constant kt‘ was estimated to be about 0.5kt, where kt is the self-Termination Rate Constant of PSt•. The formation of a 3-arm star, a possible product of cross-Termination, was evidenced by a model experiment involving the analysis by GPC-MALLS (gel permeation chromatography equipped with a multiangle laser-light scattering detector). The concentration of the 3-arm star relative to that of the doubled molecular weight linear chain produced by self-Termination of PSt• was propo...
Hadi Khan Mahabadi - One of the best experts on this subject based on the ideXlab platform.
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effect of chain length dependence of Termination Rate Constant on the kinetics of free radical polymerization 2 evaluation of an analytical expression for the Rate of polymerization
Macromolecules, 1991Co-Authors: Hadi Khan MahabadiAbstract:Etude de la cinetique non classique de la polymerisation radicalaire a basse conversion; l'expression analytique obtenue en tenant compte de la variation de la Constante de vitesse de terminaison avec la longueur de chaine est en bon accord avec les donnees de la litterature sur la polymerisation radicalaire en solution du styrene et du methacrylate de methyle
Dominik Woll - One of the best experts on this subject based on the ideXlab platform.
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diffusion of single molecular and macromolecular probes during the free radical bulk polymerization of mma towards a better understanding of the trommsdorff effect on a molecular level
Polymer Chemistry, 2016Co-Authors: Jan Martin Nolle, Sebastian Primpke, Klaus Mullen, Philipp Vana, Dominik WollAbstract:Free radical bulk polymerizations exhibit complex kinetics due to the viscosity increase during the polymerization process. Especially the Termination Rate Constant can be strongly influenced by the mobility of polymer chains in the polymerization mixture. As a consequence an autoacceleration period, the so-called Trommsdorff effect, can be observed often. In order to investigate this behaviour on a nanoscopic scale, we directly visualized the mobility of molecules and macromolecules in polymerizing MMA solutions using a combination of highly sensitive fluorescence correlation spectroscopy and widefield fluorescence microscopy. For this purpose, rather monodisperse PMMA chains were synthesized by RAFT polymerization and fluorescence-labelled with perylenediimide derivatives. The behaviour of the different fluorescent probes could be related to their size and flexibility. Our studies show that diffusional heterogeneities must be accounted for when modeling bulk polymerization.
Yungwan Kwak - One of the best experts on this subject based on the ideXlab platform.
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Rate retardation in reversible addition fragmentation chain transfer raft polymerization further evidence for cross Termination producing 3 arm star chain
Macromolecules, 2004Co-Authors: Yungwan Kwak, And Atsushi Goto, Takeshi FukudaAbstract:New pieces of experimental evidence were presented showing that the Rate retardation in the polymerization of styrene with polystyryl dithiobenzoate (PSt-SCSPh) at 60 °C is caused by the irreversible cross-Termination between the polystyryl radical (PSt•) and the intermediate radical produced by the addition of PSt• to PSt-SCSPh. The polymerization Rate Rp decreased with an increase of [PSt-SCSPh] such that a plot of 1/Rp2 vs [PSt-SCSPh] was linear, as the irreversible cross-Termination mechanism demands. The cross-Termination Rate Constant kt‘ was estimated to be about 0.5kt, where kt is the self-Termination Rate Constant of PSt•. The formation of a 3-arm star, a possible product of cross-Termination, was evidenced by a model experiment involving the analysis by GPC-MALLS (gel permeation chromatography equipped with a multiangle laser-light scattering detector). The concentration of the 3-arm star relative to that of the doubled molecular weight linear chain produced by self-Termination of PSt• was propo...
And Atsushi Goto - One of the best experts on this subject based on the ideXlab platform.
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Rate retardation in reversible addition fragmentation chain transfer raft polymerization further evidence for cross Termination producing 3 arm star chain
Macromolecules, 2004Co-Authors: Yungwan Kwak, And Atsushi Goto, Takeshi FukudaAbstract:New pieces of experimental evidence were presented showing that the Rate retardation in the polymerization of styrene with polystyryl dithiobenzoate (PSt-SCSPh) at 60 °C is caused by the irreversible cross-Termination between the polystyryl radical (PSt•) and the intermediate radical produced by the addition of PSt• to PSt-SCSPh. The polymerization Rate Rp decreased with an increase of [PSt-SCSPh] such that a plot of 1/Rp2 vs [PSt-SCSPh] was linear, as the irreversible cross-Termination mechanism demands. The cross-Termination Rate Constant kt‘ was estimated to be about 0.5kt, where kt is the self-Termination Rate Constant of PSt•. The formation of a 3-arm star, a possible product of cross-Termination, was evidenced by a model experiment involving the analysis by GPC-MALLS (gel permeation chromatography equipped with a multiangle laser-light scattering detector). The concentration of the 3-arm star relative to that of the doubled molecular weight linear chain produced by self-Termination of PSt• was propo...