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Masahiro Watanabe - One of the best experts on this subject based on the ideXlab platform.

  • synthesis and properties of anion conductive Ionomers containing fluorenyl groups for alkaline fuel cell applications
    Polymer Chemistry, 2011
    Co-Authors: Manabu Tanaka, Masaki Koike, Kenji Miyatake, Masahiro Watanabe
    Abstract:

    A series of anion conductive aromatic Ionomers, poly(arylene ether)s containing different polymer backbones and quaternized ammonio-substituted fluorenyl groups, were synthesized via nucleophilic substitution polycondensation, chloromethylation, quaternization, and the subsequent ion exchange reactions. The ion exchange capacity (IEC) of the Ionomers was controlled to be from 0.68 to 2.54 meq. g−1 by the chloromethylation reaction conditions. The designed chemical structures were well-characterized by the 1H NMR spectra. The Ionomers provided ductile and transparent membranes. The Ionomer membranes were thermally stable up to 180 °C under nitrogen and mechanically stable with 48 MPa of the maximum stress at 80 °C and 60% RH (relative humidity). High hydroxide ion conductivity up to 50 mS cm−1 was achieved at 30 °C in water for the Ionomer membrane bearing sulfone/ketone structures and the highest IEC (2.54 meq. g−1). The membranes were durable in hot water (80 °C) for 1000 hours. These properties of the Ionomer membranes seem promising as an anion exchange membrane for alkaline fuel cells.

  • tuned polymer electrolyte membranes based on aromatic polyethers for fuel cell applications
    Journal of the American Chemical Society, 2007
    Co-Authors: Kenji Miyatake, Yohei Chikashige, Eiji Higuchi, Masahiro Watanabe
    Abstract:

    Poly(arylene ether sulfone)-based Ionomers containing sulfofluorenyl groups have been synthesized for applications to polymer electrolyte membrane fuel cells (PEMFCs). In order to achieve high proton conductivity and chemical, mechanical, and dimensional stability, the molecular structure of the Ionomers has been optimized. Tough, flexible, and transparent membranes were obtained from a series of modified Ionomers containing methyl groups with the ion-exchange capacity (IEC) ranging from 1.32 to 3.26 meq/g. Isopropylidene tetramethylbiphenylene moieties were more effective than the methyl-substituted fluorenyl groups in giving a high-IEC Ionomer membrane with substantial stability to hydrolysis and oxidation. Dimensional stability was significantly improved for the methyl-substituted Ionomer membranes compared to that of the non-methylated ones. This new Ionomer membrane showed comparable proton conductivity to that of the perfluorinated Ionomer membrane (Nafion 112) under a wide range of conditions (80−1...

  • tuned polymer electrolyte membranes based on aromatic polyethers for fuel cell applications
    Journal of the American Chemical Society, 2007
    Co-Authors: Kenji Miyatake, Yohei Chikashige, Eiji Higuchi, Masahiro Watanabe
    Abstract:

    Poly(arylene ether sulfone)-based Ionomers containing sulfofluorenyl groups have been synthesized for applications to polymer electrolyte membrane fuel cells (PEMFCs). In order to achieve high proton conductivity and chemical, mechanical, and dimensional stability, the molecular structure of the Ionomers has been optimized. Tough, flexible, and transparent membranes were obtained from a series of modified Ionomers containing methyl groups with the ion-exchange capacity (IEC) ranging from 1.32 to 3.26 meq/g. Isopropylidene tetramethylbiphenylene moieties were more effective than the methyl-substituted fluorenyl groups in giving a high-IEC Ionomer membrane with substantial stability to hydrolysis and oxidation. Dimensional stability was significantly improved for the methyl-substituted Ionomer membranes compared to that of the non-methylated ones. This new Ionomer membrane showed comparable proton conductivity to that of the perfluorinated Ionomer membrane (Nafion 112) under a wide range of conditions (80-120 degrees C and 20-93% relative humidity (RH)). The highest proton conductivity of 0.3 S/cm was obtained at 80 degrees C and 93% RH. Although there is a decline of proton conductivity with time, after 10 000 h the proton conductivities were still at acceptable levels for fuel cell operation. The membranes retained their strength, flexibility, and high molecular weight after 10 000 h. Microscopic analyses revealed well-connected ionic clusters for the high-IEC membrane. A fuel cell operated using the polyether Ionomer membrane showed better performance than that of Nafion at a low humidity of 20% RH and high temperature of 90 degrees C. Unlike the other hydrocarbon Ionomers, the present membrane showed a lower resistance than expected from its conductivity, indicating superior water-holding capability at high temperature and low humidity.

  • aliphatic aromatic polyimide Ionomers as a proton conductive membrane for fuel cell applications
    Journal of the American Chemical Society, 2006
    Co-Authors: Naoki Asano, Shinsuke Suzuki, Makoto Aoki, Kenji Miyatake, Hiroyuki Uchida, Masahiro Watanabe
    Abstract:

    To produce a proton conductive and durable polymer electrolyte membrane for fuel cell applications, a series of sulfonated polyimide Ionomers containing aliphatic groups both in the main and in the side chains have been synthesized. The title polyimide Ionomers 1 with the ion exchange capacity of 1.78−2.33 mequiv/g were obtained by a typical polycondensation reaction as transparent, ductile, and flexible membranes. The proton conductivity of 1 was slightly lower than that of the perfluorinated Ionomer (Nafion) below 100 °C, but comparable at higher temperature and 100% RH. The highest conductivity of 0.18 S cm-1 was obtained for 1 at 140 °C. Ionomer 1 with high IEC and branched chemical structure exhibited improved proton conducting behavior without sacrificing membrane stability. Microscopic analyses revealed that smaller (<5 nm) and well-dispersed hydrophilic domains contribute to better proton conducting properties. Hydrogen and oxygen permeability of 1 was 1−2 orders of magnitude lower than that of Na...

Vincenzo Arcella - One of the best experts on this subject based on the ideXlab platform.

  • proton exchange membranes based on the short side chain perfluorinated Ionomer
    Journal of Power Sources, 2005
    Co-Authors: Alessandro Ghielmi, Paola Vaccarono, C Troglia, Vincenzo Arcella
    Abstract:

    Abstract Due to the renovated availability of the base monomer for the synthesis of the short-side-chain (SSC) perfluorinated Ionomer, fuel cell membrane development is being pursued using this well known Ionomer structure, which was originally developed by Dow in the 1980s. The new membranes under development have the trade name Hyflon Ion. After briefly reviewing the literature on the Dow Ionomer, new characterization data are reported on extruded Hyflon Ion membranes. The data are compared to those available in the literature on the Dow SSC Ionomer and membranes. Comparison is made also with data obtained in this work or available in the literature on the long-side-chain (LSC) perfluorinated Ionomer (Nafion). Thermal, visco-elastic, water absorption and mechanical properties of Hyflon Ion are studied. While the general behavior is similar to that shown in the past by the Dow membranes, slight differences are evident in the hydration behavior at equivalent weight (EW)   100 °C). Beginning of life fuel cell performance has also been confirmed to be higher than that given by a Nafion membrane of equal thickness.

Kenji Miyatake - One of the best experts on this subject based on the ideXlab platform.

  • synthesis and properties of anion conductive Ionomers containing fluorenyl groups for alkaline fuel cell applications
    Polymer Chemistry, 2011
    Co-Authors: Manabu Tanaka, Masaki Koike, Kenji Miyatake, Masahiro Watanabe
    Abstract:

    A series of anion conductive aromatic Ionomers, poly(arylene ether)s containing different polymer backbones and quaternized ammonio-substituted fluorenyl groups, were synthesized via nucleophilic substitution polycondensation, chloromethylation, quaternization, and the subsequent ion exchange reactions. The ion exchange capacity (IEC) of the Ionomers was controlled to be from 0.68 to 2.54 meq. g−1 by the chloromethylation reaction conditions. The designed chemical structures were well-characterized by the 1H NMR spectra. The Ionomers provided ductile and transparent membranes. The Ionomer membranes were thermally stable up to 180 °C under nitrogen and mechanically stable with 48 MPa of the maximum stress at 80 °C and 60% RH (relative humidity). High hydroxide ion conductivity up to 50 mS cm−1 was achieved at 30 °C in water for the Ionomer membrane bearing sulfone/ketone structures and the highest IEC (2.54 meq. g−1). The membranes were durable in hot water (80 °C) for 1000 hours. These properties of the Ionomer membranes seem promising as an anion exchange membrane for alkaline fuel cells.

  • tuned polymer electrolyte membranes based on aromatic polyethers for fuel cell applications
    Journal of the American Chemical Society, 2007
    Co-Authors: Kenji Miyatake, Yohei Chikashige, Eiji Higuchi, Masahiro Watanabe
    Abstract:

    Poly(arylene ether sulfone)-based Ionomers containing sulfofluorenyl groups have been synthesized for applications to polymer electrolyte membrane fuel cells (PEMFCs). In order to achieve high proton conductivity and chemical, mechanical, and dimensional stability, the molecular structure of the Ionomers has been optimized. Tough, flexible, and transparent membranes were obtained from a series of modified Ionomers containing methyl groups with the ion-exchange capacity (IEC) ranging from 1.32 to 3.26 meq/g. Isopropylidene tetramethylbiphenylene moieties were more effective than the methyl-substituted fluorenyl groups in giving a high-IEC Ionomer membrane with substantial stability to hydrolysis and oxidation. Dimensional stability was significantly improved for the methyl-substituted Ionomer membranes compared to that of the non-methylated ones. This new Ionomer membrane showed comparable proton conductivity to that of the perfluorinated Ionomer membrane (Nafion 112) under a wide range of conditions (80−1...

  • tuned polymer electrolyte membranes based on aromatic polyethers for fuel cell applications
    Journal of the American Chemical Society, 2007
    Co-Authors: Kenji Miyatake, Yohei Chikashige, Eiji Higuchi, Masahiro Watanabe
    Abstract:

    Poly(arylene ether sulfone)-based Ionomers containing sulfofluorenyl groups have been synthesized for applications to polymer electrolyte membrane fuel cells (PEMFCs). In order to achieve high proton conductivity and chemical, mechanical, and dimensional stability, the molecular structure of the Ionomers has been optimized. Tough, flexible, and transparent membranes were obtained from a series of modified Ionomers containing methyl groups with the ion-exchange capacity (IEC) ranging from 1.32 to 3.26 meq/g. Isopropylidene tetramethylbiphenylene moieties were more effective than the methyl-substituted fluorenyl groups in giving a high-IEC Ionomer membrane with substantial stability to hydrolysis and oxidation. Dimensional stability was significantly improved for the methyl-substituted Ionomer membranes compared to that of the non-methylated ones. This new Ionomer membrane showed comparable proton conductivity to that of the perfluorinated Ionomer membrane (Nafion 112) under a wide range of conditions (80-120 degrees C and 20-93% relative humidity (RH)). The highest proton conductivity of 0.3 S/cm was obtained at 80 degrees C and 93% RH. Although there is a decline of proton conductivity with time, after 10 000 h the proton conductivities were still at acceptable levels for fuel cell operation. The membranes retained their strength, flexibility, and high molecular weight after 10 000 h. Microscopic analyses revealed well-connected ionic clusters for the high-IEC membrane. A fuel cell operated using the polyether Ionomer membrane showed better performance than that of Nafion at a low humidity of 20% RH and high temperature of 90 degrees C. Unlike the other hydrocarbon Ionomers, the present membrane showed a lower resistance than expected from its conductivity, indicating superior water-holding capability at high temperature and low humidity.

  • aliphatic aromatic polyimide Ionomers as a proton conductive membrane for fuel cell applications
    Journal of the American Chemical Society, 2006
    Co-Authors: Naoki Asano, Shinsuke Suzuki, Makoto Aoki, Kenji Miyatake, Hiroyuki Uchida, Masahiro Watanabe
    Abstract:

    To produce a proton conductive and durable polymer electrolyte membrane for fuel cell applications, a series of sulfonated polyimide Ionomers containing aliphatic groups both in the main and in the side chains have been synthesized. The title polyimide Ionomers 1 with the ion exchange capacity of 1.78−2.33 mequiv/g were obtained by a typical polycondensation reaction as transparent, ductile, and flexible membranes. The proton conductivity of 1 was slightly lower than that of the perfluorinated Ionomer (Nafion) below 100 °C, but comparable at higher temperature and 100% RH. The highest conductivity of 0.18 S cm-1 was obtained for 1 at 140 °C. Ionomer 1 with high IEC and branched chemical structure exhibited improved proton conducting behavior without sacrificing membrane stability. Microscopic analyses revealed that smaller (<5 nm) and well-dispersed hydrophilic domains contribute to better proton conducting properties. Hydrogen and oxygen permeability of 1 was 1−2 orders of magnitude lower than that of Na...

Alessandro Ghielmi - One of the best experts on this subject based on the ideXlab platform.

  • proton exchange membranes based on the short side chain perfluorinated Ionomer
    Journal of Power Sources, 2005
    Co-Authors: Alessandro Ghielmi, Paola Vaccarono, C Troglia, Vincenzo Arcella
    Abstract:

    Abstract Due to the renovated availability of the base monomer for the synthesis of the short-side-chain (SSC) perfluorinated Ionomer, fuel cell membrane development is being pursued using this well known Ionomer structure, which was originally developed by Dow in the 1980s. The new membranes under development have the trade name Hyflon Ion. After briefly reviewing the literature on the Dow Ionomer, new characterization data are reported on extruded Hyflon Ion membranes. The data are compared to those available in the literature on the Dow SSC Ionomer and membranes. Comparison is made also with data obtained in this work or available in the literature on the long-side-chain (LSC) perfluorinated Ionomer (Nafion). Thermal, visco-elastic, water absorption and mechanical properties of Hyflon Ion are studied. While the general behavior is similar to that shown in the past by the Dow membranes, slight differences are evident in the hydration behavior at equivalent weight (EW)   100 °C). Beginning of life fuel cell performance has also been confirmed to be higher than that given by a Nafion membrane of equal thickness.

Robert Jerome - One of the best experts on this subject based on the ideXlab platform.