The Experts below are selected from a list of 267 Experts worldwide ranked by ideXlab platform
K Itoh - One of the best experts on this subject based on the ideXlab platform.
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analyses of spectroelectrochemical behavior of polypyrrole films using the nernst equation Monomer Unit model and polaron bipolaron model
Journal of The Electrochemical Society, 1991Co-Authors: Takashi Amemiya, Akira Fujishima, Kazuhito Hashimoto, K ItohAbstract:A series of the absorption spectrum changes in polypyrrole films were analyzed using the Nernst equation by two models. One is the "Monomer Unit model" and the other is the "polaron/bipolaron model." In the first model, formal electrode potentials and the n-values were obtained and usec~ to fit calculated hAbs vs. E curves to the experimental plots at three wavelengths. In the second model, the "apparent" excess chemical potentials were introduced to correct for the large deviations between the Nernst equation and the Nernst plots obtained from the absorption spectra. The calculated hAbs vs. E curves were then fitted to the experimental plots. The "apparent" excess chemical potentials were assigned as corrections for species concentrations. Advantages of the Monomer Unit model over the polaron/bipolaron model are pointed out in the precise analyses of the spectroelectrochemical behavior of the films.
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Analyses of Spectroelectrochemical Behavior of Polypyrrole Films Using the Nernst Equation “Monomer Unit Model” and Polaron/Bipolaron Model
Journal of The Electrochemical Society, 1991Co-Authors: Takashi Amemiya, Akira Fujishima, Kazuhito Hashimoto, K ItohAbstract:A series of the absorption spectrum changes in polypyrrole films were analyzed using the Nernst equation by two models. One is the "Monomer Unit model" and the other is the "polaron/bipolaron model." In the first model, formal electrode potentials and the n-values were obtained and usec~ to fit calculated hAbs vs. E curves to the experimental plots at three wavelengths. In the second model, the "apparent" excess chemical potentials were introduced to correct for the large deviations between the Nernst equation and the Nernst plots obtained from the absorption spectra. The calculated hAbs vs. E curves were then fitted to the experimental plots. The "apparent" excess chemical potentials were assigned as corrections for species concentrations. Advantages of the Monomer Unit model over the polaron/bipolaron model are pointed out in the precise analyses of the spectroelectrochemical behavior of the films.
Kunio Hisatani - One of the best experts on this subject based on the ideXlab platform.
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Copolymer sequence distribution with chiral stereoregularity and its application to poly(acrylonitrile-co-methacrylonitrile)
Polymer Journal, 1997Co-Authors: Kunio HisataniAbstract:An attempt was made to elucidate the general mathematical expression of the polymer sequence distribution for copolymers with two stereoregular Monomer Units by considering their chirality (D or L form) distribution based on Markov statistics. The equations derived (DL equations) were compared with those based on conventional meso and racemo conformation (mr equations) [K. Kamide and K. Hisatani, Polym. J., 24, 1377 (1992)]. For this purpose the literature data of NMR on sequence distribution of three kinds of poly(acrylonitrile-co-methacrylonitrile) i.e., poly(AN-co-MAN), prepared by radical polymerization using redox catalysis and anionic method using dialkylmagnesium as initiator at high and low temperature, were analyzed. DL equations were found to explain well the Monomer Unit sequence distribution with cotacticity of two poly(AN-co-MAN), polymerized by radical method and by anionic methods at temperatures, rather than mr equations. The reaction probability of these copolymers estimated by [Bernoulli]−[1st Markov]cor statistics where Monomer Unit sequence and its cotacticity obey Bernoulli and 1st order Markov processes, respectively, has revealed that racemo addition of MAN Monomer does not occur in the above anionic polymerization essentially. For all of three samples, the stereoregular sequences obey 1st order Markov statistics, but Monomer Unit ones obey 2nd order Markov statistics for low temperature anionic method and Bernoulli for the other two method.
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Determination Method of Sequence Distribution for Bi-component Copolymer System in Which One Monomer Unit Only Has Stereoregularity and Its Application for Poly (acrylonitrile-co-vinylidene chloride)
Polymer Journal, 1995Co-Authors: Kunio Hisatani, Kunihiko Okajima, Kenji KamideAbstract:An attempt was made to extend the method for explaining Monomer Unit sequence distribution of a bi-component copolymer system proposed already by Kamide and Hisatani, in which both Monomer Units have possibility of yielding stereoregular homopolymers, to the system in which only one Monomer is capable to give stereoregular homopolymer. The method includes a concept of correlation and non-correlation between sequence distributions of Monomer Unit and its cotacticity, and all of expressions of pentad sequences are described. Simultaneously, the sort of four kinds of n-length bi-component copolymer sequence has been enumerated up employing difference equation method, in which copolymer system only one Monomer Unit has stereoregularity. The method established in this paper was applied to poly(acrylonitrile-co-vinylidene chloride) sample as a model copolymer, of which 13C NMR peak assignment was already attained based on pentad sequence distribution [H. Yamazaki, K. Okajima, and K. Kamide, Polym. J., 20, 1143 (1988)].
Takashi Amemiya - One of the best experts on this subject based on the ideXlab platform.
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analyses of spectroelectrochemical behavior of polypyrrole films using the nernst equation Monomer Unit model and polaron bipolaron model
Journal of The Electrochemical Society, 1991Co-Authors: Takashi Amemiya, Akira Fujishima, Kazuhito Hashimoto, K ItohAbstract:A series of the absorption spectrum changes in polypyrrole films were analyzed using the Nernst equation by two models. One is the "Monomer Unit model" and the other is the "polaron/bipolaron model." In the first model, formal electrode potentials and the n-values were obtained and usec~ to fit calculated hAbs vs. E curves to the experimental plots at three wavelengths. In the second model, the "apparent" excess chemical potentials were introduced to correct for the large deviations between the Nernst equation and the Nernst plots obtained from the absorption spectra. The calculated hAbs vs. E curves were then fitted to the experimental plots. The "apparent" excess chemical potentials were assigned as corrections for species concentrations. Advantages of the Monomer Unit model over the polaron/bipolaron model are pointed out in the precise analyses of the spectroelectrochemical behavior of the films.
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Analyses of Spectroelectrochemical Behavior of Polypyrrole Films Using the Nernst Equation “Monomer Unit Model” and Polaron/Bipolaron Model
Journal of The Electrochemical Society, 1991Co-Authors: Takashi Amemiya, Akira Fujishima, Kazuhito Hashimoto, K ItohAbstract:A series of the absorption spectrum changes in polypyrrole films were analyzed using the Nernst equation by two models. One is the "Monomer Unit model" and the other is the "polaron/bipolaron model." In the first model, formal electrode potentials and the n-values were obtained and usec~ to fit calculated hAbs vs. E curves to the experimental plots at three wavelengths. In the second model, the "apparent" excess chemical potentials were introduced to correct for the large deviations between the Nernst equation and the Nernst plots obtained from the absorption spectra. The calculated hAbs vs. E curves were then fitted to the experimental plots. The "apparent" excess chemical potentials were assigned as corrections for species concentrations. Advantages of the Monomer Unit model over the polaron/bipolaron model are pointed out in the precise analyses of the spectroelectrochemical behavior of the films.
Toshiyuki Shikata - One of the best experts on this subject based on the ideXlab platform.
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hydration and dynamic behavior of poly n isopropylacrylamide s in aqueous solution a sharp phase transition at the lower critical solution temperature
Journal of the American Chemical Society, 2006Co-Authors: Toshiyuki ShikataAbstract:The number of hydrated water molecules per poly(N-isopropylacrylamide) Monomer Unit in homogeneous aqueous solution was determined to be 11 exactly and anew below the lower critical solution temperature of 32 °C employing high-frequency dielectric relaxation techniques.
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hydration and dynamic behavior of poly n isopropylacrylamide s in aqueous solution a sharp phase transition at the lower critical solution temperature
Journal of the American Chemical Society, 2006Co-Authors: Yousuke Ono, Toshiyuki ShikataAbstract:The number of hydrated water molecules per poly(N-isopropylacrylamide) Monomer Unit in homogeneous aqueous solution was determined to be 11 exactly and anew below the lower critical solution temperature of 32 degrees C employing high-frequency dielectric relaxation techniques.
Kiyohisa Fujimori - One of the best experts on this subject based on the ideXlab platform.
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Quasi tacticity of rigidly alternating copolymers of isobutyl vinyl ether and maleic anhydride
Macromolecular Rapid Communications, 2001Co-Authors: Xiao-juan Hao, Kiyohisa Fujimori, Peter C. HenryAbstract:Since the copolymers of maleic anhydride, a cyclic Monomer, and vinyl ethers, such as isobutyl vinyl ether, are made of rigidly alternating Monomer Unit sequences, quasi "isotactic" and quasi "syndiotactic" configurations for the Monomer Unit diads and triads are proposed considering the relative orientation of the cyclic anhydride group and the ether side chain with respect to the copolymer backbone.
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Relation between the alternating Monomer Unit sequence and the cis and trans linkage configurations at the cyclic maleic anhydride Units in the copolymers of styrene and maleic anhydride prepared in carbon tetrachloride
Macromolecular Chemistry and Physics, 1997Co-Authors: Kiyohisa Fujimori, Ian E. CravenAbstract:The Monomer Unit triad sequence distribution and the cis/trans linkage configurations at the cyclic maleic anhydride (MA) Units in the copolymers of styrene (ST) and MA prepared in CCl 4 with AIBN at 50°C were quantitatively determined by 13 C DEPT NMR spectroscopy. So much as 61 % of the linkages at the MA Units were found to be in cis configuration, which was considered to be formed by a participation of the 1:1 electron donor-acceptor complex formed between ST and MA in the propagation step. The mole fraction of the cis configuration was found to be proportional to the mole fraction of alternating triad sequences when the Monomer Unit sequences approach to be completely alternating. This supported the proposal that, in alternating and semi-alternating copolymerizations, the alternating sequences were formed mainly by the addition of the complex. The equilibrium constant of the complexation in CCl 4 at 23°C was determined to be 0,21 L/mol.
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Monomer Unit sequence distribution and linkage configurations at citraconic anhydride Units in the copolymers of citraconic anhydride and styrene prepared in carbon tetrachloride
Polymer Bulletin, 1997Co-Authors: Kiyohisa Fujimori, David J. TuckerAbstract:The triad Monomer Unit sequence distribution and the cis and trans linkage configurations at the cyclic citraconic anhydride Units are quantitatively determined for the copolymers of citraconic anhydride (α-methylmaleic anhydride) (CA) and styrene (ST) prepared with AIBN in CCU solutions at 50 °C. Semi-alternating copolymers are obtained for most feed compositions with rigidly alternating copolymers being formed when CA in feed is more than 90 %. Greater than 50 % of the linkages at CA Units are found to be in cis configuration in semi-alternating copolymers. This may be explained if the donor-acceptor complex formed between CA and ST participates in the copolymerization.
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Determination of Monomer Unit Sequence Distribution and Linkage Configuration of Copolymers of Styrene and Citraconic Anhydride, and Possibility of a Participation of Electron Donor-Acceptor Complex in the Copolymerization
Journal of Macromolecular Science Part A, 1997Co-Authors: Kiyohisa FujimoriAbstract:The copolymerization system of styrene (ST) and citraconic (α-methymaleic) anhydride (CA) was found to form semi-alternating copolymers when polymerized with a total Monomer concentration of 4 mol/L in CCl 4 at 50°C, with alternating copolymers being formed only when the CA mole fraction in feed was greater than 0.9. More than 50% of the linkage configurations at the cyclic CA Units in the copolymers were found to be in cis configuration. This, together with the following observations, is consistent with a participation of the electron donor-acceptor (EDA) complex formed between ST and CA: (a) the complex participation model fits best, although only marginally, to the experimental triad mole fraction of alternating sequences; (b) the alternating Monomer Unit sequences and the cis linkage configuration at the cyclic CA Units are more efficiently formed in non polar CCl 4 solutions than in polar methy ethyl ketone. The equilibrium constant for the EDA complexation of ST and CA in CCl 4 at 23°C is determined to be 0.142 ± 0.015 L/mol.