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Morphological Effect of Side Chain Length in Sulfonated Poly(arylene ether sulfone)s Polymer Electrolyte Membranes via Molecular Dynamics Simulation. Polymers (Basel) 2022; 14:polym14245499. [PMID: 36559872 PMCID: PMC9782572 DOI: 10.3390/polym14245499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Revised: 12/08/2022] [Accepted: 12/12/2022] [Indexed: 12/23/2022] Open
Abstract
With the recognition of the multiple advantages of sulfonated hydrocarbon-based polymers that possess high chemical and mechanical stability with significant low cost, we employed molecular dynamics simulation to explore the morphological effects of side chain length in sulfonated polystyrene grafted poly(arylene ether sulfone)s (SPAES) proton exchange membranes. The calculated diffusion coefficients of hydronium ions (H3O+) are in range of 0.61-1.15 × 10-7 cm2/s, smaller than that of water molecules, due to the electrical attraction between the oppositely charged sulfonate group and H3O+. The investigation into the radial distribution functions suggests that phase segregation in the SPAES membrane is more probable with longer side chains. As the hydration level of the membranes in this study is relatively low (λ = 3), longer side chains correspond to more water molecules in the amorphous cell, which provides better solvent effects for the distribution of sulfonated side chains. The coordination number of water molecules and hydronium ions around the sulfonate group increases from 1.67 to 2.40 and from 2.45 to 5.66, respectively, with the increase in the side chain length. A significant proportion of the hydronium ions appear to be in bridging configurations coordinated by multiple sulfonate groups. The microscopic conformation of the SPAES membrane is basically unaffected by temperature during the evaluated temperature range. Thus, it can be revealed that the side chain length plays a key role in the configuration of the polymer chain and would contribute to the formation of the microphase separation morphology, which profits proton transport in the hydrophilic domains.
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2
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Peng J, Wei S, Goenaga G, Weiss CM, Neal CA, Cantillo N, Zawodzinski TA. Investigate the equivalent weight effect on properties of perfluorosulfonic acid membrane in concentrated electrolytes. Electrochim Acta 2022. [DOI: 10.1016/j.electacta.2022.141151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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3
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Hu Y, Wang S, He Y, An L. Evaluation of proton transport and solvation effect in hydrated Nafion membrane with degradation. Phys Chem Chem Phys 2022; 24:29024-29033. [DOI: 10.1039/d2cp02817d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
In proton exchange membrane fuel cells (PEMFCs), free radicals easily attack ionomers, resulting in membrane degradation.
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Affiliation(s)
- Yu Hu
- School of Energy Science and Engineering, Harbin Institute of Technology, Harbin, 150001, China
| | - Shuai Wang
- School of Energy Science and Engineering, Harbin Institute of Technology, Harbin, 150001, China
| | - Yurong He
- School of Energy Science and Engineering, Harbin Institute of Technology, Harbin, 150001, China
| | - Liang An
- Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, China
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4
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Fernandez Bordín SP, Andrada HE, Carreras AC, Castellano G, Schweins R, Cuello GJ, Mondelli C, Galván Josa VM. Water channel structure of alternative perfluorosulfonic acid membranes for fuel cells. J Memb Sci 2021. [DOI: 10.1016/j.memsci.2021.119559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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5
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Zhang G, Yang G, Li S, Shen Q, Wang H, Li Z, Zhou Y, Ye W. Effects of Hydration and Temperature on the Microstructure and Transport Properties of Nafion Polyelectrolyte Membrane: A Molecular Dynamics Simulation. MEMBRANES 2021; 11:695. [PMID: 34564512 PMCID: PMC8467011 DOI: 10.3390/membranes11090695] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 09/05/2021] [Accepted: 09/06/2021] [Indexed: 11/16/2022]
Abstract
To investigate the effects of temperature and hydration on the microstructure of polymer electrolyte membrane and the transport of water molecules and hydronium ions, molecular dynamics simulations are performed on Nafion 117 for a series of water contents at different temperatures. The interactions among the sulfonate groups, hydronium ions, and water molecules are studied according to the analysis of radial distribution functions and coordination numbers. The sizes and connectivity of water clusters are also discussed, and it is found that the hydration level plays a key role in the phase separation of the membrane. However, the effect of the temperature is slight. When the water content increases from 3.5 to 16, the size of water clusters in the membrane increases, and the clusters connect to each other to form continuous channels for diffusion of water molecules and hydronium ions. The diffusion coefficients are estimated by studying the mean square displacements. The results show that the diffusion of water molecules and hydronium ions are both enhanced by the increase of the temperature and hydration level. Furthermore, the diffusion coefficient of water molecules is always much larger than that of hydronium ions. However, the ratio of the diffusion coefficient of water molecules to that of hydronium ions decreases with the increase of water content.
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Affiliation(s)
- Guoling Zhang
- Marine Engineering College, Dalian Maritime University, Dalian 116026, China; (G.Z.); (Q.S.); (H.W.); (Z.L.); (Y.Z.)
| | - Guogang Yang
- Marine Engineering College, Dalian Maritime University, Dalian 116026, China; (G.Z.); (Q.S.); (H.W.); (Z.L.); (Y.Z.)
| | - Shian Li
- Marine Engineering College, Dalian Maritime University, Dalian 116026, China; (G.Z.); (Q.S.); (H.W.); (Z.L.); (Y.Z.)
| | - Qiuwan Shen
- Marine Engineering College, Dalian Maritime University, Dalian 116026, China; (G.Z.); (Q.S.); (H.W.); (Z.L.); (Y.Z.)
| | - Hao Wang
- Marine Engineering College, Dalian Maritime University, Dalian 116026, China; (G.Z.); (Q.S.); (H.W.); (Z.L.); (Y.Z.)
| | - Zheng Li
- Marine Engineering College, Dalian Maritime University, Dalian 116026, China; (G.Z.); (Q.S.); (H.W.); (Z.L.); (Y.Z.)
| | - Yang Zhou
- Marine Engineering College, Dalian Maritime University, Dalian 116026, China; (G.Z.); (Q.S.); (H.W.); (Z.L.); (Y.Z.)
| | - Weiqiang Ye
- School of Marine Engineering, Guangzhou Maritime University, Guangzhou 510725, China;
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6
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Cha J. Morphological effect of side chain on H 3O + transfer inside polymer electrolyte membranes across polymeric chain via molecular dynamics simulation. Sci Rep 2020; 10:22014. [PMID: 33328487 PMCID: PMC7745029 DOI: 10.1038/s41598-020-77971-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 11/12/2020] [Indexed: 11/25/2022] Open
Abstract
Performance and durability of polymer electrolyte membrane are critical to fuel cell quality. As fuel cell vehicles become increasingly popular, membrane fundamentals must be understood in detail. Here, this study used molecular dynamic simulations to explore the morphological effects of perfluorosulfonic acid (PFSA)-based membranes on ionic conductivity. In particular, I developed an intuitive quantitative approach focusing principally on hydronium adsorbing to, and desorbing from, negatively charged sulfonate groups, while conventional ionic conductivity calculations featured the use of mean square displacements that included natural atomic vibrations. The results revealed that shorter side-chains caused more hydroniums to enter the conductive state, associated with higher ion conductivity. In addition, the hydronium path tracking showed that shorter side-chains allowed hydroniums to move among host groups, facilitating chain adsorption, in agreement with a mechanism suggested in earlier studies.
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Affiliation(s)
- JinHyeok Cha
- Institute of Fundamentals and Advanced Technology, Hyundai Motor Company, 37 Cheoldobangmulgwan-ro, Uiwang-si, Gyeonggi-do, 16082, Republic of Korea.
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Primachenko ON, Marinenko EA, Odinokov AS, Kononova SV, Kulvelis YV, Lebedev VT. State of the art and prospects in the development of proton‐conducting perfluorinated membranes with short side chains: A review. POLYM ADVAN TECHNOL 2020. [DOI: 10.1002/pat.5191] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Oleg N. Primachenko
- Laboratory of synthesis of high temperature resistant polymers Institute of Macromolecular Compounds of Russian Academy of Sciences Saint Petersburg Russia
| | - Elena A. Marinenko
- Laboratory of synthesis of high temperature resistant polymers Institute of Macromolecular Compounds of Russian Academy of Sciences Saint Petersburg Russia
| | - Alexey S. Odinokov
- Laboratory of synthesis of high temperature resistant polymers Institute of Macromolecular Compounds of Russian Academy of Sciences Saint Petersburg Russia
- Russian Research Center of Applied Chemistry Saint Petersburg Russia
| | - Svetlana V. Kononova
- Laboratory of synthesis of high temperature resistant polymers Institute of Macromolecular Compounds of Russian Academy of Sciences Saint Petersburg Russia
| | - Yuri V. Kulvelis
- Neutron research department Petersburg Nuclear Physics Institute, NRC “Kurchatov Institute” Gatchina Russia
| | - Vasily T. Lebedev
- Neutron research department Petersburg Nuclear Physics Institute, NRC “Kurchatov Institute” Gatchina Russia
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9
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Thoma M, Lin W, Hoffmann E, Sattes MM, Segets D, Damm C, Peukert W. Simple and Reliable Method for Studying the Adsorption Behavior of Aquivion Ionomers on Carbon Black Surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:12324-12334. [PMID: 30234996 DOI: 10.1021/acs.langmuir.8b02726] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
A better understanding of the interactions of carbon black and perfluorinated sulfonic acid (PFSA) ionomer helps to improve the effectiveness of polymer electrolyte membrane fuel cells. We present a simple and fast method for quantitative PFSA ionomer analysis based on suspension density measurements. After validation of the reliability of our method by thermogravimetric analysis and isothermal titration calorimetry (ITC), we investigate the adsorption equilibrium of short-side-chain PFSA ionomers of different equivalent weights (EW) and polarities on carbon black. The measured adsorption isotherms exhibit a plateau in the ionomer surface concentration for ionomer equilibrium concentrations ≤2 g/L. In this concentration range, the adsorption isotherms are described by the Langmuir model, whereby the surface concentrations in the plateau region are between 0.041 and 0.070 g/g. The plateau value of the ionomer surface concentration increases with EW and therefore with decreasing number of side chains with terminal sulfonic acid group per ionomer molecule, while the amount of adsorbed sulfonic acid groups remains constant for all investigated ionomers, resulting in similar ζ-potentials and sedimentation stability of the suspensions. The free energies of adsorption Δ G calculated from the association constants of the adsorption isotherms agree well with Δ G values obtained by isothermal titration calorimetry (ITC) and thus validate the adsorption isotherm measurement method. From the values of adsorption enthalpy Δ H ((-7.3 ± 0.8) kJ/mol) and entropy Δ S (ca. 100 J/(mol K)), which were extracted from ITC, we conclude that the ionomer adsorption on carbon black is a spontaneous physisorption process.
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Affiliation(s)
- Martin Thoma
- Institute of Particle Technology (LFG) , Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) , Cauerstraße 4 , D-91058 Erlangen , Germany
- Interdisciplinary Center for Functional Particle Systems (FPS) , Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) , Haberstraße 9a , D-90158 Erlangen , Germany
| | - Wei Lin
- Institute of Particle Technology (LFG) , Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) , Cauerstraße 4 , D-91058 Erlangen , Germany
- Interdisciplinary Center for Functional Particle Systems (FPS) , Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) , Haberstraße 9a , D-90158 Erlangen , Germany
| | - Eva Hoffmann
- Institute of Particle Technology (LFG) , Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) , Cauerstraße 4 , D-91058 Erlangen , Germany
- Interdisciplinary Center for Functional Particle Systems (FPS) , Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) , Haberstraße 9a , D-90158 Erlangen , Germany
| | - Maria-Melanie Sattes
- Institute of Particle Technology (LFG) , Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) , Cauerstraße 4 , D-91058 Erlangen , Germany
- Interdisciplinary Center for Functional Particle Systems (FPS) , Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) , Haberstraße 9a , D-90158 Erlangen , Germany
| | - Doris Segets
- Institute of Particle Technology (LFG) , Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) , Cauerstraße 4 , D-91058 Erlangen , Germany
- Interdisciplinary Center for Functional Particle Systems (FPS) , Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) , Haberstraße 9a , D-90158 Erlangen , Germany
| | - Cornelia Damm
- Institute of Particle Technology (LFG) , Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) , Cauerstraße 4 , D-91058 Erlangen , Germany
- Interdisciplinary Center for Functional Particle Systems (FPS) , Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) , Haberstraße 9a , D-90158 Erlangen , Germany
| | - Wolfgang Peukert
- Institute of Particle Technology (LFG) , Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) , Cauerstraße 4 , D-91058 Erlangen , Germany
- Interdisciplinary Center for Functional Particle Systems (FPS) , Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) , Haberstraße 9a , D-90158 Erlangen , Germany
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10
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Miller DD, Siriwardane R, Mcintyre D. Anion structural effects on interaction of rare earth element ions with Dowex 50W X8 cation exchange resin. J RARE EARTH 2018. [DOI: 10.1016/j.jre.2018.03.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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11
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Prakash M, Subramanian V. Ab initio and density functional theory (DFT) studies on triflic acid with water and protonated water clusters. J Mol Model 2016; 22:293. [PMID: 27888404 DOI: 10.1007/s00894-016-3158-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2016] [Accepted: 11/08/2016] [Indexed: 02/04/2023]
Abstract
The structure, stability and infrared spectral signatures of triflic acid (TA) with water clusters (Wn) and protonated water clusters (TAH+Wn, n = 1 - 6) were computed using DFT and MP2 methods. Our calculations show that a minimum of three water molecules are necessary to stabilize the dissociated zwitterionic form of TA. It can be seen from the results that there is no significant movement of protons in smaller (n = 1 and 2) and linear (n = 1 - 6) types of water clusters. Further, the geometries of TAWn clusters first form a neutral pair (NP) to contact ion pair (CIP), then form a solvent separated ion pair (SSIP) in a water hexamer. These findings reveal that proton transfer may take place through NP to CIP and then CIP to SSIP. The calculated binding energies (BEs) of ion pair clusters is always higher than that of NP clusters (i.e., more stable than the NP). Existing excess proton linear chain clusters transfer a proton to adjacent water molecules via a Grotthuss mechanism, whereas the same isomers in the branched motifs do not conduct protons. Examination of geometrical parameters and infrared frequencies reveals hydronium ion (H3O+ also called Eigen cation) formation in both TAWn and protonated TAWn clusters. The stability of Eigen water clusters is three times higher than that of other non-Eigen water clusters. Our study shows clearly that formation of ion pairs in TAWn and TAH+Wn clusters greatly favors proton transfer to neighboring water molecules and also enhances the stability of these complexes.
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Affiliation(s)
- M Prakash
- Department of Chemistry and Research Institute, SRM University, Kattankulathur, 603203, Tamil Nadu, India
- Chemical Laboratory, CSIR-Central Leather Research Institute, Adyar, Chennai, 600 020, India
| | - V Subramanian
- Chemical Laboratory, CSIR-Central Leather Research Institute, Adyar, Chennai, 600 020, India.
- Academy of Scientific and Innovative Research (AcSIR), CSIR-CLRI Campus, Chennai, 600 020, India.
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12
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Ghelichi M, Malek K, Eikerling MH. Ionomer Self-Assembly in Dilute Solution Studied by Coarse-Grained Molecular Dynamics. Macromolecules 2016. [DOI: 10.1021/acs.macromol.5b02158] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Mahdi Ghelichi
- Department
of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A
1S6, Canada
| | - Kourosh Malek
- Department
of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A
1S6, Canada
- Energy,
Mining, and Environment, National Research Council of Canada, 4250
Wesbrook Mall, Vancouver, BC V6T 1W5, Canada
| | - Michael H. Eikerling
- Department
of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A
1S6, Canada
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13
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Clark JK, Habenicht BF, Paddison SJ. Ab initio molecular dynamics simulations of aqueous triflic acid confined in carbon nanotubes. Phys Chem Chem Phys 2015; 16:16465-79. [PMID: 24983213 DOI: 10.1039/c4cp01066c] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Ab initio molecular dynamics simulations were performed to investigate the effects of nanoscale confinement on the structural and dynamical properties of aqueous triflic acid (CF3SO3H). Single-walled carbon nanotubes (CNTs) with diameters ranging from ∼11 to 14 Å were used as confinement vessels, and the inner surface of the CNT were either left bare or fluorinated to probe the influence of the confined environment on structural and dynamical properties of the water and triflic acidic. The systems were simulated at hydration levels of n = 1-3 H2O/CF3SO3H. Proton dissociation expectedly increased with increasing hydration. Along with the level of hydration, hydrogen bond connectivity between the triflic acid molecules, both directly and via a single water molecule, played a role on proton dissociation. Direct hydrogen bonding between the CF3SO3H molecules, most commonly found in the larger bare CNT, also promoted interactions between water molecules allowing for greater separation of the dissociated protons from the CF3SO3(-) as the hydration level was increased. However, this also resulted in a decrease in the overall proportion of dissociated protons. The confinement dimensions altered both the hydrogen bond network and the distribution of water molecules where the H2O in the fluorinated CNTs tended to form small clusters with less proton dissociation at n = 1 and 2 but the highest at n = 3. In the absence of nearby hydrogen bond accepting sites from H2O or triflic acid SO3H groups, the water molecules formed weak hydrogen bonds with the fluorine atoms. In the bare CNT systems, these involved the CF3 groups of triflic acid and were more frequently observed when direct hydrogen bonding between CF3SO3H hindered potential hydrogen bonding sites. In the fluorinated tubes, interactions with the covalently bound fluorine atoms of the CNT wall dominated which appear to stabilize the hydrogen bond network. Increasing the hydration level increased the frequency of the OH···F (CNT) hydrogen bonding which was highly pronounced in the smaller fluorinated CNT indicating an influence on the confinement dimensions on these interactions.
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Affiliation(s)
- Jeffrey K Clark
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN 37996, USA.
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15
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Sakai H, Tokumasu T. Reaction Analysis for Deprotonation of the Sulfonic Group of Perfluorosulfonic Acid Molecules at Low Hydration Levels. J Phys Chem A 2013; 118:275-82. [DOI: 10.1021/jp409781s] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Hironori Sakai
- Institute
of Fluid Science, Tohoku University, 2-1-1, Katahira, Sendai, Miyagi, Japan
| | - Takashi Tokumasu
- Institute
of Fluid Science, Tohoku University, 2-1-1, Katahira, Sendai, Miyagi, Japan
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Xiao P, Li J, Tang H, Wang Z, Pan M. Physically stable and high performance Aquivion/ePTFE composite membrane for high temperature fuel cell application. J Memb Sci 2013. [DOI: 10.1016/j.memsci.2013.04.014] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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17
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Kim YG, Bae YC. A particle dynamic simulation for morphological aspects of proton exchange membranes. Macromol Res 2013. [DOI: 10.1007/s13233-013-1042-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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18
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Kumar M, Edwards BJ, Paddison SJ. A macroscopic model of proton transport through the membrane-ionomer interface of a polymer electrolyte membrane fuel cell. J Chem Phys 2013; 138:064903. [DOI: 10.1063/1.4789960] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Wang C, Paddison SJ. Hydration and proton transfer in highly sulfonated poly(phenylene sulfone) ionomers: an ab initio study. J Phys Chem A 2013; 117:650-60. [PMID: 23286778 DOI: 10.1021/jp310354p] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The need to operate proton exchange membrane fuel cells under hot and dry conditions has driven the synthesis and testing of sulfonated poly(phenylene) sulfone (sPSO(2)) ionomers. The primary hydration and energetics associated with the transfer of protons in oligomeric fragments of two sPSO(2)ionomers were evaluated through first-principles electronic structures calculations. Our results indicate that the interaction between neighboring sulfonic acid groups affect both theconformation and stability of the fragments. The number of water molecules required to affect the transfer of a proton in the first hydration shell was observed to be a function of the hydrogen bonding in proximity of the sulfonic acid groups: three H(2)O for the meta- and four H(2)O for the ortho-conformations. Calculations of the rotational energy surfaces indicate that the aromatic backbones of sPSO(2) are much stiffer than the polytetrafluoroethylene (PTFE) backbones in perfluorosulfonic acid (PFSA) ionomers: the largest energy penalty for rotating phenylene rings (i.e., 15.5 kcal/mol for ortho-ortho-sPSO(2)) is nearly twice that computed for the rotation of a CF(2) unit in a PTFE backbone. The energetics for the transfer of various protons in proximity to one or two sulfonate groups (-SO(3)(-)) was also determined. The computed energy barrier for proton transfer when only one sulfonic acid group is present is approximately 1.9 kcal/mol, which is 2.1 kcal/mol lower than similar calculations for PFSA systems. When two sulfonic acid groups are bridged by water molecules, a symmetric bidirectional transfer occurs, which gives a substantially small energy barrier of only 0.7 kcal/mol.
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Affiliation(s)
- Chen Wang
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA
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20
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Economou NJ, O'Dea JR, McConnaughy TB, Buratto SK. Morphological differences in short side chain and long side chain perfluorosulfonic acid proton exchange membranes at low and high water contents. RSC Adv 2013. [DOI: 10.1039/c3ra41976b] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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21
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Subianto S, Cavaliere S, Jones DJ, Rozière J. Effect of side-chain length on the electrospinning of perfluorosulfonic acid ionomers. ACTA ACUST UNITED AC 2012. [DOI: 10.1002/pola.26286] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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22
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Zhang H, Shen PK. Recent Development of Polymer Electrolyte Membranes for Fuel Cells. Chem Rev 2012; 112:2780-832. [DOI: 10.1021/cr200035s] [Citation(s) in RCA: 1086] [Impact Index Per Article: 90.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Hongwei Zhang
- State Key Laboratory of Optoelectronic Materials and Technologies and Key Laboratory of Low-Carbon Chemistry & Energy Conservation of Guangdong Province, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275, P.R. China
| | - Pei Kang Shen
- State Key Laboratory of Optoelectronic Materials and Technologies and Key Laboratory of Low-Carbon Chemistry & Energy Conservation of Guangdong Province, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275, P.R. China
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23
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Ferrari MC, Catalano J, Giacinti Baschetti M, De Angelis MG, Sarti GC. FTIR-ATR Study of Water Distribution in a Short-Side-Chain PFSI Membrane. Macromolecules 2012. [DOI: 10.1021/ma202099p] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Maria-Chiara Ferrari
- Dipartimento di Ingegneria Chimica,
Mineraria e delle
Tecnologie Ambientali (DICMA), Alma Mater Studiorum-Università di Bologna, via Terracini 28, 40131 Bologna, Italy
| | - Jacopo Catalano
- Dipartimento di Ingegneria Chimica,
Mineraria e delle
Tecnologie Ambientali (DICMA), Alma Mater Studiorum-Università di Bologna, via Terracini 28, 40131 Bologna, Italy
| | - Marco Giacinti Baschetti
- Dipartimento di Ingegneria Chimica,
Mineraria e delle
Tecnologie Ambientali (DICMA), Alma Mater Studiorum-Università di Bologna, via Terracini 28, 40131 Bologna, Italy
| | - Maria Grazia De Angelis
- Dipartimento di Ingegneria Chimica,
Mineraria e delle
Tecnologie Ambientali (DICMA), Alma Mater Studiorum-Università di Bologna, via Terracini 28, 40131 Bologna, Italy
| | - Giulio Cesare Sarti
- Dipartimento di Ingegneria Chimica,
Mineraria e delle
Tecnologie Ambientali (DICMA), Alma Mater Studiorum-Università di Bologna, via Terracini 28, 40131 Bologna, Italy
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Devanathan R, Dupuis M. Insight from molecular modelling: does the polymer side chain length matter for transport properties of perfluorosulfonic acid membranes? Phys Chem Chem Phys 2012; 14:11281-95. [DOI: 10.1039/c2cp24132c] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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25
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Clark II JK, Paddison SJ, Hamrock SJ. The effect of hydrogen bond reorganization and equivalent weight on proton transfer in 3M perfluorosulfonic acid ionomers. Phys Chem Chem Phys 2012; 14:16349-59. [DOI: 10.1039/c2cp42678a] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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26
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Allahyarov E, Taylor PL, Löwen H. Simulation study of poled low-water ionomers with different architectures. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:455102. [PMID: 21975381 DOI: 10.1088/0953-8984/23/45/455102] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The role of the ionomer architecture in the formation of ordered structures in poled membranes is investigated by molecular dynamics computer simulations. It is shown that the length of the sidechain L(s) controls both the areal density of cylindrical aggregates N(c) and the diameter of these cylinders in the poled membrane. The backbone segment length L(b) tunes the average diameter D(s) of cylindrical clusters and the average number of sulfonates N(s) in each cluster. A simple empirical formula is noted for the dependence of the number density of induced rod-like aggregates on the sidechain length L(s) within the parameter range considered in this study.
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Affiliation(s)
- Elshad Allahyarov
- Department of Physics, Case Western Reserve University, Cleveland, OH 44106, USA
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27
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Habenicht BF, Paddison SJ. Ab Initio Simulations of the Effects of Nanoscale Confinement on Proton Transfer in Hydrophobic Environments. J Phys Chem B 2011; 115:10826-35. [DOI: 10.1021/jp205787f] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Bradley F. Habenicht
- Department of Chemical & Biomolecular Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Stephen J. Paddison
- Department of Chemical & Biomolecular Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States
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28
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Affiliation(s)
- Shulu Feng
- Department of Chemistry, James Franck Institute and Computational Institute, University of Chicago, 5735 S Ellis Ave., Chicago, Illinois 60637, United States
| | - Gregory A. Voth
- Department of Chemistry, James Franck Institute and Computational Institute, University of Chicago, 5735 S Ellis Ave., Chicago, Illinois 60637, United States
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29
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Hayes RL, Paddison SJ, Tuckerman ME. Proton transport in triflic acid pentahydrate studied via ab initio path integral molecular dynamics. J Phys Chem A 2011; 115:6112-24. [PMID: 21434672 DOI: 10.1021/jp110953a] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Trifluoromethanesulfonic acid hydrates provide a well-defined system to study proton dissociation and transport in perfluorosulfonic acid membranes, typically used as the electrolyte in hydrogen fuel cells, in the limit of minimal water. The triflic acid pentahydrate crystal (CF(3)SO(3)H·5H(2)O) is sufficiently aqueous that it contains an extended three-dimensional water network. Despite it being extended, however, long-range proton transport along the network is structurally unfavorable and would require considerable rearrangement. Nevertheless, the triflic acid pentahydrate crystal system can provide a clear picture of the preferred locations of local protonic defects in the water network, which provides insights about related structures in the disordered, low-hydration environment of perfluorosulfonic acid membranes. Ab initio molecular dynamics simulations reveal that the proton defect is most likely to transfer to the closest water that has the expected presolvation and only contains water in its first solvation shell. Unlike the tetrahydrate of triflic acid (CF(3)SO(3)H·4H(2)O), there is no evidence of the proton preferentially transferring to a water molecule bridging two of the sulfonate groups. However, this could be an artifact of the crystal structure since the only such water molecule is separated from the proton by long O-O distances. Hydrogen bonding criteria, using the two-dimensional potential of mean force, are extracted. Radial distribution functions, free energy profiles, radii of gyration, and the root-mean-square displacement computed from ab initio path integral molecular dynamics simulations reveal that quantum effects do significantly extend the size of the protonic defect and increase the frequency of proton transfer events by nearly 15%. The calculated IR spectra confirm that the dominant protonic defect mostly exists as an Eigen cation but contains some Zundel ion characteristics. Chain lengths and ring sizes determined from the hydrogen bond network, counted using graph theory techniques, are only moderately sensitive to quantum effects. Deliberately introducing a structural defect into the native crystal yields a protonic defect with one hydrogen bond to a sulfonate group that was found to be metastable for at least 10 ps.
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Affiliation(s)
- Robin L Hayes
- Department of Chemistry, New York University, New York, New York, USA
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30
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Ahadian S, Mizuseki H, Kawazoe Y. Effects of hydration level, temperature, side chain and backbone flexibility of the polymer on the proton transfer in short-side-chain perfluorosulfonic acid membranes at low humidity conditions. J Memb Sci 2011. [DOI: 10.1016/j.memsci.2010.12.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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31
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Allahyarov E, Taylor PL. Simulation study of the equilibrium morphology in ionomers with different architectures. ACTA ACUST UNITED AC 2011. [DOI: 10.1002/polb.22191] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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32
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Luo X, Holdcroft S, Mani A, Zhang Y, Shi Z. Water, proton, and oxygen transport in high IEC, short side chain PFSA ionomer membranes: consequences of a frustrated network. Phys Chem Chem Phys 2011; 13:18055-62. [DOI: 10.1039/c1cp22559f] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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33
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Wu D, Paddison SJ, Elliott JA, Hamrock SJ. Mesoscale modeling of hydrated morphologies of 3M perfluorosulfonic acid-based fuel cell electrolytes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:14308-14315. [PMID: 20704341 DOI: 10.1021/la102358y] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Dissipative particle dynamics (DPD) simulations have been carried out to study the hydrated morphology of 3M perfluorosulfonic acid (PFSA) fuel cell membranes as a function of the equivalent weight (EW), molecular weight (MW), and hydration level. The 3M PFSA ionomers were modeled using typical EWs of 578, 640, and 790 g/mol, and molecular weights were varied from about 45,000 to 90,000 g/mol in order to be close to the experimental range. The morphology changes corresponding to the EW, MW, and hydration level were comparatively investigated by inspecting the water distributions, followed by quantitative analysis by radial distribution functions and Bragg spacing according to the periodicity of water domains. Compared to the morphologies of short-side-chain PFSA membrane (Wu, D.; Paddison, S. J.; Elliott, J. A. Macromolecules 2009, 42, 3358-3367), the longer side chain in 3M PFSA membrane provides more flexibility for the sulfonate-terminated side chains and generally results in the stronger aggregation of water clusters. This results in lower water uptake for higher EW, corresponding to a lower ion-exchange capacity (IEC), which is attributed experimentally to a higher crystallinity of the fluorocarbon phase, although our simulations were not able to observe the crystallites directly.
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Affiliation(s)
- Dongsheng Wu
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA
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34
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Yana J, Nimmanpipug P, Chirachanchai S, Gosalawit R, Dokmaisrijan S, Vannarat S, Vilaithong T, Lee VS. Molecular dynamics simulations of Krytox-Silica–Nafion composite for high temperature fuel cell electrolyte membranes. POLYMER 2010. [DOI: 10.1016/j.polymer.2010.07.036] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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35
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Habenicht BF, Paddison SJ, Tuckerman ME. Ab initio molecular dynamics simulations investigating proton transfer in perfluorosulfonic acid functionalized carbon nanotubes. Phys Chem Chem Phys 2010; 12:8728-32. [PMID: 20556301 DOI: 10.1039/c0cp00130a] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Proton dissociation and transfer were examined with ab initio molecular dynamics (AIMD) simulations of carbon nanotubes (CNT) functionalized with perfluorosulfonic acid (-CF(2)SO(3)H) groups with 1-3 H(2)O/SO(3)H. The CNT systems were constructed both with and without fluorine atoms covalently bound to the walls to elucidate the effects of the presence of a strongly hydrophobic environment, the fluorine, on proton dissociation, hydration, and stabilization. The simulations revealed that the dissociated proton was preferentially stabilized as a hydrated hydronium cation (i.e., Eigen like) in the fluorinated CNTs but as a Zundel (H(5)O(2)(+)) cation in the nonfluorinated CNTs. This feature is attributed to the fluorine atoms forming hydrogen bonds with the water molecules coordinated to the central hydronium ion.
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Affiliation(s)
- Bradley F Habenicht
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA
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36
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Allahyarov E, Taylor PL, Löwen H. Simulation study of field-induced morphological changes in a proton-conducting ionomer. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2010; 81:031805. [PMID: 20365763 DOI: 10.1103/physreve.81.031805] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2009] [Revised: 01/24/2010] [Indexed: 05/29/2023]
Abstract
A simulation study was made of the effects of strong electric fields on the morphology of a Nafion-like ionomer at various levels of hydration. The results of united-atom molecular-dynamics computations showed a self-organization of the side chain terminal groups into cylindrical clusters. The walls of these clusters contain the sulfonate dipoles, while the interior holds the majority of the water molecules. These cylindrical structures then align to form an hexatic array aligned along the direction of the applied electric field. The hexatic morphology persists after the removal of the field. A calculation by means of the Kirkwood coupling parameter method shows the Helmholtz free energy of the hexatic morphology of the poled membrane to be lower than that of the initial isotropic material, even in the absence of the applied field.
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Affiliation(s)
- Elshad Allahyarov
- Department of Physics, Case Western Reserve University, Cleveland, Ohio 44106, USA
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37
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Hayes RL, Paddison SJ, Tuckerman ME. Proton transport in triflic acid hydrates studied via path integral car-parrinello molecular dynamics. J Phys Chem B 2010; 113:16574-89. [PMID: 19968267 DOI: 10.1021/jp907853p] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The mono-, di-, and tetrahydrates of trifluoromethanesulfonic acid, which contain characteristic H(3)O(+), H(5)O(2)(+), and H(9)O(4)(+) structures, provide model systems for understanding proton transport in materials with high perfluorosulfonic acid density such as perfluorosulfonic acid membranes commonly employed in hydrogen fuel cells. Ab initio molecular dynamics simulations indicate that protons in these solids are predisposed to transfer to the water most strongly bound to sulfonate groups via a Grotthuss-type mechanism, but quickly return to the most solvated defect structure either due to the lack of a nearby species to stabilize the new defect or a preference for the proton to be maximally hydrated. Path integral molecular dynamics of the mono- and dihydrate reveal significant quantum effects that facilitate proton transfer to the "presolvated" water or SO(3)(-) in the first solvation shell and increase the Zundel character of all the defects. These trends are quantified in free energy profiles for each bonding environment. Hydrogen bonding criteria for HOH-OH(2) and HOH-O(3)S are extracted from the two-dimensional potential of mean force. The quantum radial distribution function, radius of gyration, and root-mean-square displacement position correlation function show that the protonic charge is distributed over two or more water molecules. Metastable structural defects with one excess proton shared between two sulfonate groups and another Zundel or Eigen type cation defect are found for the mono- and dihydrate but not for the tetrahydrate crystal. Results for the tetrahydrate native crystal exhibit minor differences at 210 and 250 K. IR spectra are calculated for all native and stable defect structures. Graph theory techniques are used to characterize the chain lengths and ring sizes in the hydrogen bond network. Low conductivities when limited water is present may be attributable to trapping of protons between SO(3)(-) groups and the increased probability that protons transfer to waters bridging two different sulfonate groups.
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Affiliation(s)
- Robin L Hayes
- Department of Chemistry, New York University, New York, USA
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38
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Knox CK, Voth GA. Probing Selected Morphological Models of Hydrated Nafion Using Large-Scale Molecular Dynamics Simulations. J Phys Chem B 2010; 114:3205-18. [DOI: 10.1021/jp9112409] [Citation(s) in RCA: 120] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Craig K. Knox
- Departments of Chemistry and Chemical Engineering and Center for Biophysical Modeling and Simulation, Room 2020, 315 South 1400 East, University of Utah, Salt Lake City, Utah 84112-0850
| | - Gregory A. Voth
- Departments of Chemistry and Chemical Engineering and Center for Biophysical Modeling and Simulation, Room 2020, 315 South 1400 East, University of Utah, Salt Lake City, Utah 84112-0850
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39
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Wu D, Paddison SJ, Elliott JA. Effect of Molecular Weight on Hydrated Morphologies of the Short-Side-Chain Perfluorosulfonic Acid Membrane. Macromolecules 2009. [DOI: 10.1021/ma900016w] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Dongsheng Wu
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, Tennessee 37996, and Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge, CB2 3QZ, U.K
| | - Stephen J. Paddison
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, Tennessee 37996, and Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge, CB2 3QZ, U.K
| | - James A. Elliott
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, Tennessee 37996, and Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge, CB2 3QZ, U.K
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40
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Page KA, Park JK, Moore RB, Garcia Sakai V. Direct Analysis of the Ion-Hopping Process Associated with the α-Relaxation in Perfluorosulfonate Ionomers Using Quasielastic Neutron Scattering. Macromolecules 2009. [DOI: 10.1021/ma801533h] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Kirt A. Page
- Polymers Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, Department of Chemistry, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, and Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742
| | - Jong Keun Park
- Polymers Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, Department of Chemistry, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, and Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742
| | - Robert B. Moore
- Polymers Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, Department of Chemistry, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, and Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742
| | - Victoria Garcia Sakai
- Polymers Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, Department of Chemistry, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, and Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742
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41
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Bowyer WJ, Xu W, Demas JN. Determining proton diffusion in polymer films by lifetimes of luminescent complexes measured in the frequency domain. Anal Chem 2009; 81:378-84. [PMID: 19035648 DOI: 10.1021/ac8016554] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Polymer-supported luminescent metal complexes represent an important class of oxygen, pH, and ion sensors. The diffusion properties of the analyte into the sensing film are important for rational sensor and support design and development. We describe a technique using lifetime measurements in the frequency domain for determining the diffusion coefficient of hydrochloric acid through various polymeric pH sensor films. Two types of polymers are doped with [Ru(4,7-diphenyl-1,10-phenanthroline)2(4,4'-dicarboxy-2,2'-bipyridine)]Cl2. We monitor the phase shift of luminescence (from which we calculate the apparent lifetime, tau(app)) versus time after applying a step increase in the aqueous HCl concentration at the surfaces of the film. We model the decrease in tau(app) as a function of time using the diffusion coefficient of HCl in the polymer as the only adjustable parameter. The model accurately predicts the lifetime versus time curves, and the resulting diffusion coefficients are highly dependent on the polymer. Relative to bulk water, diffusion of protons within very hydrophilic hydrated D4 polymer (a polyethylene oxide cross-linked siloxane ring polymer) films is hindered approximately 4-fold, while within a more hydrophobic sol gel it is hindered by over 1 order of magnitude. The methodology is adaptable for measuring diffusion coefficients of a variety of analytes in different sensor films as long as the bound and unbound forms luminescence and the excited states have different lifetimes.
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Affiliation(s)
- Walter J Bowyer
- Department of Chemistry, Hobart and William Smith Colleges, Geneva, New York 14456, USA.
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42
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Allahyarov E, Taylor PL. Simulation Study of the Correlation between Structure and Conductivity in Stretched Nafion. J Phys Chem B 2008; 113:610-7. [DOI: 10.1021/jp8047746] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Elshad Allahyarov
- Department of Physics, Case Western Reserve University, Cleveland, Ohio 44106, and Joint Institute of High Temperatures, Russian Academy of Sciences (IVTAN), Moscow 125412, Russia
| | - Philip L. Taylor
- Department of Physics, Case Western Reserve University, Cleveland, Ohio 44106
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43
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Ji X, Yan L, Zhu S, Zhang L, Lu W. Methanol Distribution and Electroosmotic Drag in Hydrated Poly(perfluorosulfonic) Acid Membrane. J Phys Chem B 2008; 112:15616-27. [DOI: 10.1021/jp8066469] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Xiaobo Ji
- School of Material Science and Engineering, Department of Chemistry, College of Sciences, Shanghai University, 99 Shangda Road, Shanghai 200444, China
| | - Liuming Yan
- School of Material Science and Engineering, Department of Chemistry, College of Sciences, Shanghai University, 99 Shangda Road, Shanghai 200444, China
| | - Suhua Zhu
- School of Material Science and Engineering, Department of Chemistry, College of Sciences, Shanghai University, 99 Shangda Road, Shanghai 200444, China
| | - Liangmiao Zhang
- School of Material Science and Engineering, Department of Chemistry, College of Sciences, Shanghai University, 99 Shangda Road, Shanghai 200444, China
| | - Wencong Lu
- School of Material Science and Engineering, Department of Chemistry, College of Sciences, Shanghai University, 99 Shangda Road, Shanghai 200444, China
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44
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Cui S, Liu J, Selvan ME, Paddison SJ, Keffer DJ, Edwards BJ. Comparison of the hydration and diffusion of protons in perfluorosulfonic acid membranes with molecular dynamics simulations. scui@utk.edu. J Phys Chem B 2008; 112:13273-84. [PMID: 18826266 DOI: 10.1021/jp8039803] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Classical molecular dynamics (MD) simulations were performed to determine the hydrated morphology and hydronium ion diffusion coefficients in two different perfluorosulfonic acid (PFSA) membranes as functions of water content. The structural and transport properties of 1143 equivalent weight (EW) Nafion, with its relatively long perfluoroether side chains, are compared to the short-side-chain (SSC) PFSA ionomer at an EW of 977. The separation of the side chains was kept uniform in both ionomers consisting of -(CF 2) 15- units in the backbone, and the degree of hydration was varied from 5 to 20 weight % water. The MD simulations indicated that the distribution of water clusters is more dispersed in the SSC ionomer, which leads to a more connected water-channel network at the low water contents. This suggests that the SSC ionomer may be more inclined to form sample-spanning aqueous domains through which transport of water and protons may occur. The diffusion coefficients for both hydronium ions and water molecules were calculated at hydration levels of 4.4, 6.4, 9.6, and 12.8 H 2O/SO 3H for each ionomer. When compared to experimental proton diffusion coefficients, this suggests that as the water content is increased the contribution of proton hopping to the overall proton diffusion increases.
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Affiliation(s)
- Shengting Cui
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, Tennessee, 37996-2200, USA.
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