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Shimanuki J, Imai H, Ito Y, Nishino Y, Miyazawa A. Microstructural observation of the swollen catalyst layers of fuel cells by cryo-TEM. Microscopy (Oxf) 2023; 72:60-63. [PMID: 36401875 DOI: 10.1093/jmicro/dfac059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2022] [Revised: 09/29/2022] [Accepted: 11/16/2022] [Indexed: 11/21/2022] Open
Abstract
It is important to understand and control the fine structure of the fuel cell catalyst layer in order to improve the battery characteristics of the fuel cell. A major challenge in observing the microstructure of the catalyst layer by electron microscopy is the visualization of ionomers, which have low contrast and are susceptible to damage by electron beam irradiation. Previous papers have reported transmission electron microscopy (TEM) observations of ionomers neutralized with cesium (Cs) ions. However, this approach involves chemical reactions and indirect visualization of ionomers. In contrast, we have previously revealed the microstructure of ionomers in frozen catalyst inks by cryogenic (cryo) scanning electron microscopy and cryo-TEM. In general, ionomers are basically used under high-temperature and humid conditions while the fuel cell is operating. Therefore, in this study, ultrathin sections prepared from the fuel cell catalyst layer (membrane electrode assemblies) were incubated in a chamber under high-temperature and humid conditions and then rapidly frozen for observation by cryo-TEM. As a result, we succeeded in observing the pore structure of the catalyst layer in the swollen state of the ionomer. The swollen ionomer surrounded and enclosed the Pt/C aggregates and bridged over the pores in the catalyst layer.
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Affiliation(s)
- Junichi Shimanuki
- Phenomenon Analysis Department, NISSAN ARC LTD, 1 Natsushima-cho, Yokosuka, Kanagawa 237-0061, Japan
| | - Hideto Imai
- Phenomenon Analysis Department, NISSAN ARC LTD, 1 Natsushima-cho, Yokosuka, Kanagawa 237-0061, Japan
| | - Yoshiko Ito
- Life Science & Research Division, Leica Microsystems, 1-29-9 Takadanobaba, Shinjuku-ku, Tokyo 169-0075, Japan.,Graduate School of Science, University of Hyogo, 3-2-1 Kouto, Kamigori-cho, Ako-gun, Hyogo 678-1297, Japan
| | - Yuri Nishino
- Graduate School of Science, University of Hyogo, 3-2-1 Kouto, Kamigori-cho, Ako-gun, Hyogo 678-1297, Japan
| | - Atsuo Miyazawa
- Graduate School of Science, University of Hyogo, 3-2-1 Kouto, Kamigori-cho, Ako-gun, Hyogo 678-1297, Japan
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Kizas O, Moiseev S, Chaschin I, Godovikov I, Dolgushin F, Khokhlov A. New unsaturated sulfur-containing heterocycles derived from 1,3-dithiane or 1,3,5-trithiane and α -ferrocenylvinyl cation generated from ethynylferrocene. J Organomet Chem 2022. [DOI: 10.1016/j.jorganchem.2022.122358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Kizas O, Moiseev S, Chaschin I, Godovikova M, Dolgushin F, Khokhlov A. Sulfonium salts derived from α-ferrocenylvinyl cation in situ generated in sc-CO2 from ethynylferrocene by nafion film. J Supercrit Fluids 2019. [DOI: 10.1016/j.supflu.2019.104544] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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5
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Rorrer JE, Bell AT, Toste FD. Synthesis of Biomass-Derived Ethers for Use as Fuels and Lubricants. CHEMSUSCHEM 2019; 12:2835-2858. [PMID: 31232521 DOI: 10.1002/cssc.201900535] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Revised: 04/20/2019] [Accepted: 05/08/2019] [Indexed: 06/09/2023]
Abstract
Ethers synthesized from biomass-derived compounds have exceptional properties as fuels, lubricants, and specialty chemicals and can serve as replacements for petroleum-derived products. Recent efforts have identified heterogeneous catalysts for the selective synthesis of ethers from alcohols, aldehydes, ketones, furans, esters, olefins, carboxylic acids, and other molecules derived from biomass. This Review highlights the scope of etherification reactions and provides insights into the choice of catalysts and reaction conditions best suited for producing targeted ethers from the available starting materials. First, the properties of ethers for specific applications and the methods by which synthons for ether synthesis can be obtained from biomass are discussed. Then the progress that has been made on the synthesis of ethers via the following methods is summarized: direct etherification of alcohols; reductive etherification of alcohols with aldehydes or ketones; etherification of furanic compounds, esters, and carboxylic acids; and the addition of alcohols to olefins. Next, the mechanisms of these reactions and catalyst properties required to promote them are discussed, with the goal of understanding how reaction conditions can be tuned to optimize catalyst activity and selectivity towards desired ethers. The Review closes by examining the tradeoffs between catalyst selectivity, activity, stability, and reaction conditions required to achieve the most economically and environmentally favorable routes to biomass-derived ethers.
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Affiliation(s)
- Julie E Rorrer
- Department of Chemical and Biomolecular Engineering, University of California Berkeley, CA, 94720, USA
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Alexis T Bell
- Department of Chemical and Biomolecular Engineering, University of California Berkeley, CA, 94720, USA
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - F Dean Toste
- Department of Chemistry, University of California Berkeley, CA, 94720, USA
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
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Semenova D, Silina YE, Koch M, Micheli L, Zubov A, Gernaey KV. Sensors for biosensors: a novel tandem monitoring in a droplet towards efficient screening of robust design and optimal operating conditions. Analyst 2019; 144:2511-2522. [DOI: 10.1039/c8an02261e] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Development of a tandem monitoring approach that allows the simultaneous on-line detection of multiple biosensor system parameters.
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Affiliation(s)
- Daria Semenova
- Process and Systems Engineering Center (PROSYS)
- Department of Chemical and Biochemical Engineering
- Technical University of Denmark
- 2800 Kgs. Lyngby
- Denmark
| | - Yuliya E. Silina
- INM – Leibniz Institute for New Materials
- 66123 Saarbrücken
- Germany
| | - Marcus Koch
- INM – Leibniz Institute for New Materials
- 66123 Saarbrücken
- Germany
| | - Laura Micheli
- Department of Chemical Science and Technologies
- Università di Roma Tor Vergata
- 00133 Rome
- Italy
| | - Alexandr Zubov
- Process and Systems Engineering Center (PROSYS)
- Department of Chemical and Biochemical Engineering
- Technical University of Denmark
- 2800 Kgs. Lyngby
- Denmark
| | - Krist V. Gernaey
- Process and Systems Engineering Center (PROSYS)
- Department of Chemical and Biochemical Engineering
- Technical University of Denmark
- 2800 Kgs. Lyngby
- Denmark
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7
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Modification of Nafion membrane by polyaniline providing uniform polymer distribution throughout the membrane. Colloid Polym Sci 2018. [DOI: 10.1007/s00396-018-4431-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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8
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Kang S, Pyo JB, Kim TS. Layer-by-Layer Assembly of Free-Standing Nanofilms by Controlled Rolling. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:5831-5836. [PMID: 29708348 DOI: 10.1021/acs.langmuir.8b01063] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
A water surface not only provides a habitat to many living organisms but also opens up new possibilities to develop state-of-the-art technologies. Here, we show a technology for the layer-by-layer assembly of free-standing nanofilms by controlled rolling. The water surface is exploited as an ideal platform for rolling a nanofilm, allowing adhesion control and frictionless feeding. The nanofilm floating on the water surface is attached to a tube by van der Waals adhesion and is rolled up by the rotation of the tube. This method can assemble diverse film materials including metals, polymers, and two-dimensional materials, with an easy control of the number of layers. Furthermore, heterogeneous and spiral structures of the nanofilm are achieved. Various applications such as a stretchable tubular electrode, an electroactive polymer tube actuator, and a superelastic nanofilm tube are demonstrated. We believe this work can potentially lead to a breakthrough in the nanofilm assembly processes.
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Affiliation(s)
- Sumin Kang
- Department of Mechanical Engineering , Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141 , Republic of Korea
| | - Jae-Bum Pyo
- Department of Mechanical Engineering , Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141 , Republic of Korea
| | - Taek-Soo Kim
- Department of Mechanical Engineering , Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141 , Republic of Korea
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Rasouli H, Naji L, Hosseini MG. 3D structured polypyrrole/reduced graphene oxide (PPy/rGO)-based electrode ionic soft actuators with improved actuation performance. NEW J CHEM 2018. [DOI: 10.1039/c8nj00936h] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report a facile approach to fabricate 3D polypyrrole/reduced graphene oxide (PPy/rGO)-based electrodes for Nafion-based ionic soft actuators.
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Affiliation(s)
- Haleh Rasouli
- Department of Chemistry
- Amirkabir University of Technology
- Tehran
- Iran
| | - Leila Naji
- Department of Chemistry
- Amirkabir University of Technology
- Tehran
- Iran
| | - Mir Ghasem Hosseini
- Electrochemistry Research Laboratory
- Department of Physical Chemistry
- Chemistry Faculty
- University of Tabriz
- Tabriz
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Kizas O, Moiseev S, Chaschin I, Godovikov I, Dolgushin F, Nikolaev A, Nikitin L, Khokhlov A. Phosphonium salts derived from α-ferrocenylvinyl cation in situ generated in sc -CO 2 from ethynylferrocene by Nafion film. J Supercrit Fluids 2018. [DOI: 10.1016/j.supflu.2017.09.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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11
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Yoo T, Aziz MA, Oh K, Shanmugam S. Modified sulfonated Poly(arylene ether) multiblock copolymers containing highly sulfonated blocks for polymer electrolyte membrane fuel cells. J Memb Sci 2017. [DOI: 10.1016/j.memsci.2017.08.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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12
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Kizas OA, Chaschin IS, Godovikov IA, Dolgushin FM, Antonov DY, Nikitin LN, Khokhlov AR. Generation of ferrocenylvinyl cation CpFeC 5 H 4 –C + =CH 2 by protonation of ferrocenylacetylene with Nafion and its reactions with SMe 2 and PPh 3 in scCO 2 giving onium salts. MENDELEEV COMMUNICATIONS 2017. [DOI: 10.1016/j.mencom.2017.07.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Safari M, Naji L, Baker RT, Afshar Taromi F. Influence of electrolytes of Li salts, EMIMBF4, and mixed phases on electrochemical and physical properties of Nafion membrane. J Appl Polym Sci 2017. [DOI: 10.1002/app.45239] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- Maryam Safari
- Department of Chemistry; AmirKabir University of Technology; P.O Box: 15875-4413 Tehran Iran
| | - Leila Naji
- Department of Chemistry; AmirKabir University of Technology; P.O Box: 15875-4413 Tehran Iran
| | - Richard T. Baker
- EaStChem, School of Chemistry; University of St. Andrews; St. Andrews Fife KY16 9ST United Kingdom
| | - Faramarz Afshar Taromi
- Faculty of Color and Polymer Engineering; AmirKabir University of Technology; P.O Box: 15875-4413 Tehran Iran
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Pašti IA, Janošević Ležaić A, Ćirić-Marjanović G, Mirsky VM. Resistive gas sensors based on the composites of nanostructured carbonized polyaniline and Nafion. J Solid State Electrochem 2016. [DOI: 10.1007/s10008-016-3344-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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15
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Ghosh S, Chakrabarti R. Molecular dynamics simulation elucidates the preferential binding affinity of sodium and tetramethylammonium ions for tetrameric Nafion unit under aqueous conditions. RSC Adv 2016. [DOI: 10.1039/c6ra21845h] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Preferential binding interaction of sodium and tetramethylammonium cations with Nafion pendant and backbone sites respectively.
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Affiliation(s)
- Soumadwip Ghosh
- Department of Chemistry
- Indian Institute of Technology Bombay
- Mumbai – 400076
- India
| | - Rajarshi Chakrabarti
- Department of Chemistry
- Indian Institute of Technology Bombay
- Mumbai – 400076
- India
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Safari M, Naji L, Baker RT, Taromi FA. The enhancement effect of lithium ions on actuation performance of ionic liquid-based IPMC soft actuators. POLYMER 2015. [DOI: 10.1016/j.polymer.2015.09.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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17
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Willeman H, Hance P, Fertin A, Voedts N, Duhal N, Goossens JF, Hilbert JL. A method for the simultaneous determination of chlorogenic acid and sesquiterpene lactone content in industrial chicory root foodstuffs. ScientificWorldJournal 2014; 2014:583180. [PMID: 25548785 PMCID: PMC4274826 DOI: 10.1155/2014/583180] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Accepted: 10/03/2014] [Indexed: 11/17/2022] Open
Abstract
A method for the simultaneous determination of free chlorogenic acids (CGA) and sesquiterpene lactones (STL) in chicory root and its dried (flour) and roasted (grain) forms is described. The method uses one extraction and one analysis for all chicory root products. Various solvents with low to high polarity, such as methanol, chloroform, or n-hexane, were tested alone, in combination in different proportions or with acidified or neutral aqueous solvent. The water/chloroform/methanol (30/30/40, v/v/v) mixture generated the best extraction yield, 21% higher than alcohol mixtures. The profiling of CGA and STL content was performed through a conventional HPLC-DAD method using a PFP core shell column in a fast single run. Good retention time and area repeatability (RDD mean % 0.46 and 5.6, resp.) and linearity (R2≥0.96) were obtained. The STL and chlorogenic acids levels determined were 254.7 and 100.2 μg/g of dry matter in the root, 792.5 and 1,547 μg/g in flour, and 160.4 and 822.5 μg/g in the roasted grains, respectively. With an average recovery of 106% and precision of 90%, this method is rapid, reproducible, and straightforward way to quantify the chlorogenic acids and STL in chicory raw material and end products.
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Affiliation(s)
- Honorine Willeman
- UMR 1281, Stress Abiotiques et Différenciation des Végétaux Cultivés, GIS GENOCHIC, INRA, IFR147, Université Lille 1 Sciences et Technologies, Cité Scientifique, 59655 Villeneuve d'Ascq, France
| | - Philippe Hance
- UMR 1281, Stress Abiotiques et Différenciation des Végétaux Cultivés, GIS GENOCHIC, INRA, IFR147, Université Lille 1 Sciences et Technologies, Cité Scientifique, 59655 Villeneuve d'Ascq, France
| | - Anne Fertin
- IUT A, Département Génie Biologique, Université Lille 1 Sciences et Technologies, 59655 Villeneuve d'Ascq, France
| | - Najia Voedts
- UMR 1281, Stress Abiotiques et Différenciation des Végétaux Cultivés, GIS GENOCHIC, INRA, IFR147, Université Lille 1 Sciences et Technologies, Cité Scientifique, 59655 Villeneuve d'Ascq, France
| | - Nathalie Duhal
- Faculté des Sciences Pharmaceutiques et Biologiques, Centre Universitaire de Mesures et d'Analyses (CUMA), Université Lille 2, BP 83, 3 rue du Pr. Laguesse, 59006 Lille Cedex, France
| | - Jean-François Goossens
- Faculté des Sciences Pharmaceutiques et Biologiques, Centre Universitaire de Mesures et d'Analyses (CUMA), Université Lille 2, BP 83, 3 rue du Pr. Laguesse, 59006 Lille Cedex, France
| | - Jean-Louis Hilbert
- UMR 1281, Stress Abiotiques et Différenciation des Végétaux Cultivés, GIS GENOCHIC, INRA, IFR147, Université Lille 1 Sciences et Technologies, Cité Scientifique, 59655 Villeneuve d'Ascq, France
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Hooshyari K, Javanbakht M, Naji L, Enhessari M. Nanocomposite proton exchange membranes based on Nafion containing Fe2TiO5 nanoparticles in water and alcohol environments for PEMFC. J Memb Sci 2014. [DOI: 10.1016/j.memsci.2013.11.033] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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19
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Li Y, Nguyen QT, Buquet CL, Langevin D, Legras M, Marais S. Water sorption in Nafion® membranes analyzed with an improved dual-mode sorption model—Structure/property relationships. J Memb Sci 2013. [DOI: 10.1016/j.memsci.2013.03.040] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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20
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Kizas OA, Antonov DY, Vopilov YE, Godovikov IA, Peregudov AS, Kagramanov ND, Bulatnikova LN, Nikitin LN, Khokhlov AR. Hydration of terminal alkynes on Nafion film in supercritical carbon dioxide. J Supercrit Fluids 2013. [DOI: 10.1016/j.supflu.2013.02.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Vasil'ev VV, Borisov SM, Maldotti A, Molinari A. Spectral properties of cationic water-soluble metallo-porphyrins immobilized in a perfluorosulfonated ion-exchange membrane. J PORPHYR PHTHALOCYA 2012. [DOI: 10.1142/s1088424603000963] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The behavior of palladium(II), platinum(II) and rhodium(III) complexes with two cationic water-soluble porphyrins: meso-tetrakis(4-N-methylpyridyl)porphyrin and meso-tetrakis(4-N,N,N-trimethylaminophenyl)porphyrin in Nafion® membrane and in Nafion® solution have been studied by UV-visible absorption and emission spectroscopy. All metalloporphyrins are localized in the interfacial region of Nafion®. The six-coordinate Rh(III) complexes are monomeric inside Nafion®, but immobilized four-coordinate Pd(II) and Pt(II) complexes form face-to-face dimers with a characteristic blue shifted Soret band. All immobilized complexes exhibit a strong red phosphorescence at room temperature in the absence of oxygen. Phosphorescence decays for all metalloporphyrins were found to be a single exponential but phosphorescence lifetimes noticeably increased in the Nafion® membrane as compared to lifetimes in aqueous solution.
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Affiliation(s)
- Victor V. Vasil'ev
- Department of Chemistry, Russian State Pedagogical University, Moyka 48, St. Petersburg, 191186, Russia
| | - Sergey M. Borisov
- Department of Chemistry, Russian State Pedagogical University, Moyka 48, St. Petersburg, 191186, Russia
| | - Andrea Maldotti
- Dipartimento di Chimica, I.S.O.F. C.N.R., Sezione di Ferrara, Via L. Borsari 46, Ferrara, 44100, Italy
| | - Alessandra Molinari
- Dipartimento di Chimica, I.S.O.F. C.N.R., Sezione di Ferrara, Via L. Borsari 46, Ferrara, 44100, Italy
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Incorporation of Hyperbranched Supramolecules into Nafion Ionic Domains via Impregnation and In-Situ Photopolymerization. Polymers (Basel) 2011. [DOI: 10.3390/polym3042018] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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23
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Wu X, Wang X, He G, Benziger J. Differences in water sorption and proton conductivity between Nafion and SPEEK. ACTA ACUST UNITED AC 2011. [DOI: 10.1002/polb.22326] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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24
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Wang C, Paddison SJ. Proton transfer in functionalized phosphonic acid molecules. Phys Chem Chem Phys 2010; 12:970-81. [DOI: 10.1039/b917903h] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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25
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Satterfield MB, Benziger JB. Viscoelastic properties of Nafion at elevated temperature and humidity. ACTA ACUST UNITED AC 2008. [DOI: 10.1002/polb.21608] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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26
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Majsztrik PW, Bocarsly AB, Benziger JB. Viscoelastic Response of Nafion. Effects of Temperature and Hydration on Tensile Creep. Macromolecules 2008. [DOI: 10.1021/ma801811m] [Citation(s) in RCA: 115] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Rivera H, Lawton JS, Budil DE, Smotkin ES. Effect of Sorbed Methanol, Current, and Temperature on Multicomponent Transport in Nafion-Based Direct Methanol Fuel Cells. J Phys Chem B 2008; 112:8542-8. [DOI: 10.1021/jp803158h] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Harry Rivera
- Department of Chemistry, University of Puerto Rico at Rio Piedras, San Juan, Puerto Rico 00931, and Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts, 02115
| | - Jamie S. Lawton
- Department of Chemistry, University of Puerto Rico at Rio Piedras, San Juan, Puerto Rico 00931, and Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts, 02115
| | - David E. Budil
- Department of Chemistry, University of Puerto Rico at Rio Piedras, San Juan, Puerto Rico 00931, and Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts, 02115
| | - Eugene S. Smotkin
- Department of Chemistry, University of Puerto Rico at Rio Piedras, San Juan, Puerto Rico 00931, and Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts, 02115
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Onishi LM, Prausnitz JM, Newman J. Water-Nafion equilibria. absence of Schroeder's paradox. J Phys Chem B 2007; 111:10166-73. [PMID: 17685645 DOI: 10.1021/jp073242v] [Citation(s) in RCA: 142] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Water-Nafion phase equilibria and proton conductivities were measured in two ways. First, Nafion was in contact with saturated water vapor. Second, Nafion was in contact with liquid water at the same temperature. At 29 degrees C, for preboiled, vapor-equilibrated Nafion exposed to water with an activity = 1 and air pressures ranging from 0 to 0.96 bar, the water content was lambda = 23 +/- 1 mol H(2)O/mol SO3-. For the preboiled, liquid-equilibrated membrane, lambda = 24 +/- 2. At 100% relative humidity (RH), the water content of preboiled Nafion decreased as the temperature rose from 30 to 80 degrees C but did not recover its initial water content when the temperature returned to 30 degrees C. The water content of predried Nafion at 1 atm and 30 degrees C was lambda = 13.7 +/- 0.2 when vapor-equilibrated and lambda = 13.1 +/- 0.5 when liquid-equilibrated. A Nafion membrane originally boiled in water had much higher liquid- and 100% RH vapor-equilibrated proton conductivities than the same membrane originally dried at 110 degrees C with a RH less than 2%. The liquid-equilibrated and 100% RH vapor-equilibrated membrane conductivities were the same when the membrane had the same thermal history. The conductivity data was fit to a model, and the water content was determined at different temperatures. The predried membrane water content increased with temperature, and the preboiled membrane's water content changed slightly with temperature. Both water sorption and proton-conductivity data do not exhibit Schroeder's paradox. These studies and previous results suggest that Schroeder's paradox is resolved when attention is given to the thermal history of the absorbing polymer.
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Affiliation(s)
- Lisa M Onishi
- Department of Chemical Engineering, University of California, Berkeley, California 94720-1462, USA.
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Elliott JA, Paddison SJ. Modelling of morphology and proton transport in PFSA membranes. Phys Chem Chem Phys 2007; 9:2602-18. [PMID: 17627306 DOI: 10.1039/b701234a] [Citation(s) in RCA: 194] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Computational modelling studies of the structure of perfluorosulfonic acid (PFSA) ionomer membranes consistently exhibit a nanoscopic phase-separated morphology in which the ionic side chains and aqueous counterions segregate from the fluorocarbon backbone to form clusters or channels. Although these investigations do not unambiguously predict the size or shape of the clusters, and whether or not the channels percolate the matrix or if the connections between them are more transient, the sequence of co-monomers along the main chain appears strongly to influence the domain size of the ionic regions, with more blocky sequences giving rise to larger domain sizes. The fundamental insight that substantial rearrangement of the sulfonic acid terminated side chains and fluorocarbon backbone takes place during swelling or shrinkage is borne out by both molecular and mesoscale simulations of model PFSA polymers, along with ab initio electronic structure calculations of minimally hydrated oligomeric fragments. Molecular-level modelling of proton transport in PFSA membranes attests to the complexity of the underlying mechanisms and the need to examine the chemical and physical processes at several distinct time and length scales. These investigations have revealed that the conformation of the fluorocarbon backbone, flexibility of the sidechains, and degree of aggregation and association of the sulfonic acid groups under minimally hydrated conditions collectively control the dissociation of the protons and the formation of Zundel and Eigen cations. The former appear to be the dominant charge carriers when the limiting water content allows only for the formation of a contact ion pair with the tethered sulfonate anion. As the water content increases, solvent-separated Eigen ions begin to appear, indicating that the dominant mechanism for diffusion of protons occurs over a region approximately 4 A away from the sulfonate groups. Finally, both the vehicular and Grotthuss shuttling mechanisms contribute to the mobility of the protons but, surprisingly, they are not always correlated, resulting in a lower overall diffusion coefficient. In summary, as the preceding observations indicate, the state of computational modelling of PFSA membranes has progressed sufficiently over the last decade to enable its use as a powerful predictive tool with which to guide the process of designing novel membrane materials for fuel cell applications.
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Affiliation(s)
- James A Elliott
- Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge, CB2 3QZ, UK.
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Aleksandrova E, Hiesgen R, Friedrich KA, Roduner E. Electrochemical atomic force microscopy study of proton conductivity in a Nafion membrane. Phys Chem Chem Phys 2007; 9:2735-43. [PMID: 17627317 DOI: 10.1039/b617516c] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
High membrane conductivity is one of the key parameters in polymer electrolyte fuel cell applications. We introduce an electrochemical atomic force microscopy method that provides simultaneously the surface topography of a Nafion 112 membrane and the conductivity of ion channels with an unprecedented resolution of ca. 10 nm. For given conditions, a large fraction of the channel ports is found to conduct exactly the same number of protons per unit time. This is taken as evidence for an optimum pore size and structure for proton conduction, or alternatively, for an efficient connectivity of the ion channel network, so that the same conductivity is measured at all exit pores. The time response following a potential step and the influence of the relative humidity on the transport properties is investigated. The method will be of relevance for tailoring the production technology to yield an optimised micromorphology, and it permits detailed tests of membrane models and provides data for theoretical modelling of proton conductivity.
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Affiliation(s)
- Elena Aleksandrova
- Institut für Physikalische Chemie, Universität Stuttgart, Pfaffenwaldring 55, 70569, Stuttgart, Germany
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Chourdakis N, Voyiatzis GA. Molecular orientation study of uniaxially drawn nafion polymer electrolyte membranes utilizing polarized UV–Raman spectra. ACTA ACUST UNITED AC 2007. [DOI: 10.1002/polb.21250] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Weber AZ, Newman J. Macroscopic Modeling of Polymer-Electrolyte Membranes. ADVANCES IN FUEL CELLS 2007. [DOI: 10.1016/s1752-301x(07)80007-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Andreadis G, Tsiakaras P. Ethanol crossover and direct ethanol PEM fuel cell performance modeling and experimental validation. Chem Eng Sci 2006. [DOI: 10.1016/j.ces.2006.08.028] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Gromadzki D, Černoch P, Janata M, Kůdela V, Nallet F, Diat O, Štěpánek P. Morphological studies and ionic transport properties of partially sulfonated diblock copolymers. Eur Polym J 2006. [DOI: 10.1016/j.eurpolymj.2006.05.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Umemura K, Wang T, Hara M, Kuroda R, Uchida O, Nagai M. Nanocharacterization and nanofabrication of a Nafion thin film in liquids by atomic force microscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2006; 22:3306-12. [PMID: 16548593 DOI: 10.1021/la051926t] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
We demonstrated the nanocharacterization and nanofabrication of a Nafion thin film using atomic force microscopy (AFM). AFM images showed that the Nafion molecules form nanoclusters in water, in 5% methanol, and in acetic acid. Young's modulus E of a Nafion film was estimated by sequential force curve measurements in water and in 5% methanol on one sample surface. Ewater/E5% methanol was 1.75 +/- 0.40, so the film was much softer in 5% methanol than in water. Even when solvent was replaced from 5% methanol to water, Young's modulus was not recovered soon. We showed the first example of the mechanical properties of a Nafion film on the nanoscale. Furthermore, we succeeded in fabricating 3D nanostructures on a Nafion surface by AFM nanolithography in liquids. Our results showed the new potential of the AFM nanolithography of a polymer film by softening the molecules in liquids.
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Affiliation(s)
- Kazuo Umemura
- Research Center for Energy and Environment Science, Musashi Institute of Technology, 1-28-1 Tamazutsumi, Setagaya, Tokyo 158-8557, Japan.
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Paddison SJ, Kreuer KD, Maier J. About the choice of the protogenic group in polymer electrolyte membranes: Ab initio modelling of sulfonic acid, phosphonic acid, and imidazole functionalized alkanes. Phys Chem Chem Phys 2006; 8:4530-42. [PMID: 17047750 DOI: 10.1039/b611221h] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The possible use of sulfonic acid, phosphonic acid, or imidazole as the protogenic group in polymer electrolyte membranes for fuel cells operating at intermediate temperature (T>100 degrees C) and very low humidity conditions is examined by comparing specific molecular properties obtained with first principles based electronic structure calculations. Potential energy profiles determined at the B3LYP/6-311G** level for rotation of imidazole, phosphonic acid and sulfonic acid functional groups on saturated heptyl chains revealed that the torsional barriers are 3.9, 10.0, and 15.9 kJ mol-1, respectively; indicating that the imidazole is clearly the most labile when tethered to an alkyl chain. Minimum energy conformations (B3LYP/6-311G**) of methyl dimers of each of the acids indicated that the binding of the pairs of the acids is greatest in the phosphonic acids and lowest for the imidazoles. Comparison of the ZPE corrected total energies of the methyl acid dimers with corresponding pairs consisting of the conjugate acid and conjugate base revealed that the energy penalty in transferring the proton (from acid to acid) was greatest for imidazole (120.1 kJ mol-1) and least for the phosphonic acid (37.2 kJ mol-1). This result is in agreement with experimentally measured proton conductivities of acid-functionalized heptyl compounds under dry conditions and further underpins the observation that phosphonic acid possesses the best amphoteric character critical in achieving proton conductivity when no solvent (i.e. water) is present. Finally, BSSE corrected binding energies were computed for the methyl acids with a single water molecule and indicated that while the magnitude of the interaction of the sulfonic and phosphonic acids with water are similar (47.3 and 44.4 kJ mol-1, respectively), the binding is much weaker to the imidazole (28.8 kJ mol-1). This result suggests that the oxo-acids will probably retain water better under very low humidity conditions and that the dynamics of the hydrogen bonding of the first hydration water molecules will be more constrained with -SO3H and -PO3H2 than imidazole.
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Affiliation(s)
- Stephen J Paddison
- Department of Chemistry and Materials Science, University of Alabama in Huntsville, Huntsville, Alabama 35899, USA.
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Paul R, Paddison SJ. Effects of dielectric saturation and ionic screening on the proton self-diffusion coefficients in perfluorosulfonic acid membranes. J Chem Phys 2005; 123:224704. [PMID: 16375492 DOI: 10.1063/1.2131051] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Proton transport in perfluorosulfonic acid (PFSA) membranes is investigated through a statistical mechanical model that includes the effects of the interaction of the tethered sulfonate groups with both the water and solvated protons. We first derive a potential that describes the electrostatic field due to the dissociated sulfonic acid groups by extending the work of Gronbech-Jensen et al. [ Mol. Phys. 92, 941 (1997)] to a finite array of point charges. A highly convergent series is obtained which includes the effects of screening due to the protons. We then investigate the effects of both dielectric saturation and two distinct formulations of ionic screening on the proton self-diffusion coefficient in Nafion membranes over a range of water contents. Our computations show that the two phenomena (i.e., dielectric saturation and ionic screening) under constant temperature conditions result in canceling affects. Our calculations provide a radial dependence of the proton mobility suggesting that the dominant self-diffusion occurs in the central region of the pores, well separated from the sulfonate groups. Through comparison of our calculated diffusion coefficients with the experimental values we derived a slightly smaller average separation distance of the hydronium ion from the sulfonate ions than suggested by either electronic structure calculations or multistate empirical valence bond molecular-dynamics simulations.
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Affiliation(s)
- Reginald Paul
- Department of Chemistry, University of Calgary, Calgary, Alberta T2N 1N4, Canada
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Wang S, Sun G, Wang G, Zhou Z, Zhao X, Sun H, Fan X, Yi B, Xin Q. Improvement of direct methanol fuel cell performance by modifying catalyst coated membrane structure. Electrochem commun 2005. [DOI: 10.1016/j.elecom.2005.07.003] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Sangribsub S, Tangboriboonrat P, Pith T, Decher G. Hydrophobization of multilayered film containing layer-by-layer assembled nanoparticle by Nafion adsorption. Polym Bull (Berl) 2005. [DOI: 10.1007/s00289-005-0353-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Elliott J, Hanna S, Newton J, Elliott A, Cooley G. Elimination of orientation in perfluorinated ionomer membranes. POLYM ENG SCI 2005. [DOI: 10.1002/pen.20478] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Affoune AM, Yamada A, Umeda M. Surface observation of solvent-impregnated Nafion membrane with atomic force microscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2004; 20:6965-6968. [PMID: 15301471 DOI: 10.1021/la036329q] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Surface morphology modification of the Nafion 117 membrane has been investigated by atomic force microscopy. The effects of water and methanol on the topography and structure of the surface were studied using the contact and tapping atomic force microscopy modes. Nafion topography considerably changes when samples absorb water. However, samples stored in methanol are characterized by flat surfaces. Surface modification was linked to an expansion phenomenon during the swelling of Nafion by solvents. Tapping-mode phase images showed that ionic and cluster domains are distinguishable from the surface of samples impregnated either in water or methanol.
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Affiliation(s)
- Abed M Affoune
- Department of Chemistry, Nagaoka University of Technology, Kamitomioka 1603-1, Nagaoka, Niigata 940-2188, Japan
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Structure alterations of perfluorinated sulfocationic membranes under the action of ethylene glycol (SAXS and WAXS studies). POLYMER 2003. [DOI: 10.1016/s0032-3861(03)00588-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Amatore C, Sella C, Thouin L. Effects of chemical environment on diffusivities within thin Nafion® films as monitored from chronoamperometric responses of generator–collector double microband assemblies. J Electroanal Chem (Lausanne) 2003. [DOI: 10.1016/s0022-0728(03)00195-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Kim J, Kim B, Jung B. Proton conductivities and methanol permeabilities of membranes made from partially sulfonated polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene copolymers. J Memb Sci 2002. [DOI: 10.1016/s0376-7388(02)00138-2] [Citation(s) in RCA: 173] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Young SK, Trevino SF, Beck Tan NC. Small-angle neutron scattering investigation of structural changes in nafion membranes induced by swelling with various solvents. ACTA ACUST UNITED AC 2002. [DOI: 10.1002/polb.10092] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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