Radiation-Grafted Polymer Electrolyte Membranes for Fuel Cells

Abstract

Fuel cells are one of the most efficient energy conversion systems to produce electricity. A solid ion-conducting polymer membrane is employed as both separator and electrolyte for polymer electrolyte membrane fuel cells and anion-exchange membrane fuel cells. Radiation-induced graft polymerization is a versatile method for the fabrication of low-cost alternatives to commercial polymer membranes. In this method, typically a base polymer is exposed to ionizing radiation which generates active radical sites within the polymer substrate. Then a suitable vinyl monomer is polimerized on these active sites to form a graft copolymer. Finally, a subsequent chemical treatment is performed to introduce hydrophilic groups to hydrophobic polymer backbone so that an ion conducting membrane is formed. There are various studies about the influence of radiation grafting parameters on membrane properties. Moreover, the favorable fuel cell relevant and polarization properties of such radiation-grafted membranes were reported. Thus, radiation-grafted polymer membranes are one of the significant low-cost alternatives for fuel cells. This review focuses on the preparation, characterization of fuel cell relevant properties and fuel cell performance of radiation-grafted membranes.

Keywords

• Polymer electrolyte
• membrane
• radiation-induced grafting
• fuel cell

References

1. [1] Wang Y, Ruiz Diaz DF, Chen KS, Wang Z, Adroher XC. Materials, technological status, and fundamentals of PEM fuel cells – A review. Mater Today 2020;32:178–203. https://doi.org/10.1016/j.mattod.2019.06.005.
2. [2] Xing L, Shi W, Su H, Xu Q, Das PK, Mao B, et al. Membrane electrode assemblies for PEM fuel cells: A review of functional graded design and optimization. Energy 2019;177:445–64. https://doi.org/10.1016/j.energy.2019.04.084.
3. [3] Dekel DR. Review of cell performance in anion exchange membrane fuel cells. J Power Sources 2018;375:158–69. https://doi.org/10.1016/j.jpowsour.2017.07.117.
4. [4] Borup R, Meyers J, Pivovar B, Kim YS, Mukundan R, Garland N, et al. Scientific aspects of polymer electrolyte fuel cell durability and degradation. Chem Rev 2007;107:3904–51. https://doi.org/10.1021/cr050182l.
5. [5] Varcoe JR, Atanassov P, Dekel DR, Herring AM, Hickner MA, Kohl PA, et al. Anion-exchange membranes in electrochemical energy systems. Energy Environ Sci 2014;7:3135–91. https://doi.org/10.1039/c4ee01303d.
6. [6] Nasef MM, Gürsel SA, Karabelli D, Güven O. Radiation-grafted materials for energy conversion and energy storage applications. Prog Polym Sci 2016;63:1–41.
7. [7] Peighambardoust SJ, Rowshanzamir S, Amjadi M. Review of the proton exchange membranes for fuel cell applications. Int J Hydrogen Energy 2010;35:9349–84.
8. [8] Gubler L, Beck N, Gürsel SA, Hajbolouri F, Kramer D, Reiner A, et al. Materials for polymer electrolyte fuel cells. Chim Int J Chem 2004;58:826–36.

9. [9] Gubler L, Scherer GG. Trends for fuel cell membrane development. Desalination 2010;250:1034–7.
10. [10] Mauritz KA, Moore RB. State of understanding of Nafion. Chem Rev 2004;104:4535–86.
11. [11] Schmidt-Rohr K, Chen Q. Parallel cylindrical water nanochannels in Nafion fuel-cell membranes. Nat Mater 2008;7:75–83.
12. [12] Tripathi BP, Shahi VK. Organic–inorganic nanocomposite polymer electrolyte membranes for fuel cell applications. Prog Polym Sci 2011;36:945–79.
13. [13] Gubler L, Gürsel SA, Scherer GG. Radiation grafted membranes for polymer electrolyte fuel cells. Fuel Cells 2005;5:317–35. https://doi.org/10.1002/fuce.200400078.
14. [14] Gubler L, Scherer GG. Durability of radiation-grafted fuel cell membranes. Polym. electrolyte fuel cell Durab., Springer; 2009, p. 133–55.
15. [15] Nasef MM, Hegazy ESA. Preparation and applications of ion exchange membranes by radiation-induced graft copolymerization of polar monomers onto non-polar films. Prog Polym Sci 2004;29:499–561. https://doi.org/10.1016/j.progpolymsci.2004.01.003.
16. [16] Nasef MM, Güven O. Radiation-grafted copolymers for separation and purification purposes: Status, challenges and future directions. Prog Polym Sci 2012;37:1597–656.
17. [17] Gürsel SA, Wokaun A, Scherer GG. Influence of reaction parameters on grafting of styrene into poly (ethylene-alt-tetrafluoroethylene) films. Nucl Instruments Methods Phys Res Sect B Beam Interact with Mater Atoms 2007;265:198–203.
18. [18] Paronen M, Sundholm F, Rauhala E, Lehtinen T, Hietala S. Effects of irradiation on sulfonation of poly(vinyl fluoride). J Mater Chem 1997;7:2401–6. https://doi.org/10.1039/a705822e.
19. [19] Fisher WK, Corelli JC. Effect of Ionizing Radiation on the Chemical Composition, Crystalline Content and Structure, and Flow Properties of Polytetrafluoroethylene. J Polym Sci A1 1981;19:2465–93. https://doi.org/10.1002/pol.1981.170191010.
20. [20] Lunkwitz K, Brink HJ, Handte D, Ferse A. The radiation degradation of polytetrafluoroethylene resulting in low-molecular and functionalized perfluorinated compounds. Int J Radiat Appl Instrumentation Part 1989;33:523–32. https://doi.org/10.1016/1359-0197(89)90309-3.
21. [21] Bürger W, Lunkwitz K, Pompe G, Petr A, Jehnichen D. Radiation degradation of fluoropolymers: Carboxylated fluoropolymers from radiation degradation in presence of air. J Appl Polym Sci 1993;48:1973–85. https://doi.org/10.1002/app.1993.070481111.
22. [22] Lappan U, Häußler L, Pompe G, Lunkwitz K. Thermal stability of electron beam-irradiated polytetrafluoroethylene. J Appl Polym Sci 1997;66:2287–91. https://doi.org/10.1002/(sici)1097-4628(19971219)66:12<2287::aid-app10>3.3.co;2-h.
23. [23] Hill DJT, Mohajerani S, Pomery PJ, Whittaker AK. An ESR study of the radiation chemistry of poly (tetrafluoroethylene-co-hexafluoropropylene) at 77 and 300 K. Radiat Phys Chem 2000;59:295–302. https://doi.org/10.1016/S0969-806X(00)00272-3.
24. [24] Dargaville TR, Hill DJT, Whittaker AK. An ESR study of irradiated poly(tetrafluoroethylene-co-perfluoropropyl vinyl ether) (PFA). Radiat Phys Chem 2001;62:25–31. https://doi.org/10.1016/S0969-806X(01)00418-2.
25. [25] Oshima A, Seguchi T, Tabata Y. ESR study on free radicals trapped in crosslinked polytetrafluoroethylene (PTFE). Radiat Phys Chem 1997;50:601–6. https://doi.org/10.1016/S0969-806X(97)00079-0.
26. [26] Lunkwitz K, Lappan U, Lehmann D. Modification of fluoropolymers by means of electron beam irradiation. Radiat Phys Chem 2000;57:373–6. https://doi.org/10.1016/S0969-806X(99)00407-7.
27. [27] Brack HP, Buhrer HG, Bonorand L, Scherer GG. Grafting of pre-irradiated poly(ethylene-alt-tetrafluoroethylene) films with styrene: Influence of base polymer film properties and processing parameters. J Mater Chem 2000;10:1795–803. https://doi.org/10.1039/b001851l.
28. [28] Walsby N, Sundholm F, Kallio T, Sundholm G. Radiation-grafted ion-exchange membranes: Influence of the initial matrix on the synthesis and structure. J Polym Sci Part A Polym Chem 2001;39:3008–17. https://doi.org/10.1002/pola.1281.
29. [29] Chen J, Asano M, Maekawa Y, Yoshida M. Suitability of some fluoropolymers used as base films for preparation of polymer electrolyte fuel cell membranes. J Memb Sci 2006;277:249–57. https://doi.org/10.1016/j.memsci.2005.10.036.
30. [30] Chen J, Septiani U, Asano M, Maekawa Y, Kubota H, Yoshida M. Comparative study on the preparation and properties of radiation-grafted polymer electrolyte membranes based on fluoropolymer films. J Appl Polym Sci 2007;103:1966–72. https://doi.org/10.1002/app.24950.
31. [31] Hegazy EA, Ishigaki I, Okamoto J. Radiation grafting of acrylic acid onto fluorine-containing polymers. I. Kinetic study of preirradiation grafting onto poly(tetrafluoroethylene). J Appl Polym Sci 1981;26:3117–24. https://doi.org/10.1002/app.1981.070260925.
32. [32] Brack HP, Scherer GG. Modification and characterization of thin polymer films for electrochemical applications. Macromol Symp 1998;126:25–49. https://doi.org/10.1002/masy.19981260105.
33. [33] Momose T, Yoshioka H, Ishigaki I, Okamoto J. Radiation grafting of α,β,β-trifluorostyrene onto poly(ethylene-tetrafluoroethylene) film by preirradiation method. II. Properties of cation-exchange membrane obtained by sulfonation and hydrolysis of the grafted film. J Appl Polym Sci 1989;38:2091–101. https://doi.org/10.1002/app.1989.070381111.
34. [34] Chapiro A. Préparation des copolymères greffés du polytetrafluoroéthylène (Teflon) par voie radiochimique. J Polym Sci 1959;34:481–501. https://doi.org/10.1002/pol.1959.1203412735.
35. [35] Gupta B, Scherer GG. Proton-Exchange Membranes by Radiation-Induced Graft-Copolymerization of Monomers into Teflon-Fep Films. Chimia (Aarau) 1994;48:127–37.
36. [36] Guersel SA, Gubler L, Gupta B, Scherer GG. Radiation grafted membranes. Fuel cells I, Springer; 2008, p. 157–217.
37. [37] Phadnis S, Patri M, Hande VR, Deb PC. Proton exchange membranes by grafting of styrene-acrylic acid onto FEP by preirradiation technique. I. Effect of synthesis conditions. J Appl Polym Sci 2003;90:2572–7. https://doi.org/10.1002/app.12727.
38. [38] Liang GZ, Lu TL, Ma XY, Yan HX, Gong ZH. Synthesis and characteristics of radiation-grafted membranes for fuel cell electrolytes. Polym Int 2003;52:1300–8. https://doi.org/10.1002/pi.1220.
39. [39] Rager T. Pre-irradiation grafting of styrene/divinylbenzene onto poly(tetrafluoroethylene-co-hexafluoropropylene) from non-solvents. Helv Chim Acta 2003;86:1966–81. https://doi.org/10.1002/hlca.200390155.
40. [40] Nasef MM. Effect of solvents on radiation-induced grafting of styrene onto fluorinated polymer films. Polym Int 2001;50:338–46. https://doi.org/10.1002/pi.634.
41. [41] Nasef MM, Saidi H, Nor HM, Foo OM. Proton exchange membranes prepared by simultaneous radiation grafting of styrene onto poly(tetrafluoroethylene-co-hexafluoropropylene) films. II. Properties of sulfonated membranes. J Appl Polym Sci 2000;78:2443–53. https://doi.org/10.1002/1097-4628(20001227)78:14<2443::AID-APP30>3.0.CO;2-E.
42. [42] Nasef MM, Saidi H. Preparation of crosslinked cation exchange membranes by radiation grafting of styrene/divinylbenzene mixtures onto PFA films. J Memb Sci 2003;216:27–38. https://doi.org/10.1016/S0376-7388(03)00027-9.
43. [43] Dargaville TR, George GA, Hill DJT, Whittaker AK. High energy radiation grafting of fluoropolymers. Prog Polym Sci 2003;28:1355–76. https://doi.org/10.1016/S0079-6700(03)00047-9.
44. [44] Rager T. Parameter Study for the Pre-Irradiation Grafting of Styrene/Divinylbenzene onto Poly(tetrafluoroethylene-co-hexafluoropropylene) from Isopropanol Solution. Helv Chim Acta 2004;87:400–7. https://doi.org/10.1002/hlca.200490038.
45. [45] Büchi FN, Gupta B, Haas O, Scherer GG. Study of radiation-grafted FEP-G-polystyrene membranes as polymer electrolytes in fuel cells. Electrochim Acta 1995;40:345–53. https://doi.org/10.1016/0013-4686(94)00274-5.
46. [46] Rouilly M V., Kötz ER, Haas O, Scherer GG, Chapiró A. Proton exchange membranes prepared by simultaneous radiation grafting of styrene onto Teflon-FEP films. Synthesis and characterization. J Memb Sci 1993;81:89–95. https://doi.org/10.1016/0376-7388(93)85033-S.
47. [47] Gupta B, Büchi FN, Staub M, Grman D, Scherer GG. Cation exchange membranes by pre-irradiation grafting of styrene into FEP films. II. Properties of copolymer membranes. J Polym Sci Part A Polym Chem 1996;34:1873–80. https://doi.org/10.1002/(SICI)1099-0518(19960730)34:10<1873::AID-POLA4>3.0.CO;2-Q.
48. [48] Gupta B, Anjum N, Gupta AP. Development of membranes by radiation grafting of acrylamide into polyethylene films: Influence of synthesis conditions. J Appl Polym Sci 2000;77:1331–7. https://doi.org/10.1002/1097-4628(20000808)77:6<1331::AID-APP18>3.0.CO;2-M.
49. [49] Cardona F, George GA, Hill DJT, Rasoul F, Maeji J. Copolymers obtained by the radiation-induced grafting of styrene onto poly(tetrafluoroethylene-co-perfluoropropylvinyl ether) substrates. 1. Preparation and structural investigation. Macromolecules 2002;35:355–64. https://doi.org/10.1021/ma0022295.
50. [50] Cardona F, George GA, Hill DJT, Perera S. Spectroscopic study of the penetration depth of grafted polystyrene onto poly(tetrafluoroethylene-co-perfluoropropylvinylether) substrates. 1. Effect of grafting conditions. J Polym Sci Part A Polym Chem 2002;40:3191–9. https://doi.org/10.1002/pola.10409.
51. [51] Finch CA. Polymer handbook: Third edition Edited by J. Brandrup and E. H. Immergut, Wiley-Interscience, Chichester, 1989. pp. ix + parts I to VIII, price £115·00/$;175·00. ISBN 0–471–81244–7. Br Polym J 1990;23:277–277. https://doi.org/10.1002/pi.4980230318.
52. [52] Hegazy EA, Taher NH, Kamal H. Preparation and properties of cationic membranes obtained by radiation grafting of methacrylic acid onto PTFE films. J Appl Polym Sci 1989;38:1229–42. https://doi.org/10.1002/app.1989.070380704.
53. [53] Walsby N, Paronen M, Juhanoja J, Sundholm F. Sulfonation of styrene-grafted poly(vinylidene fluoride) films. J Appl Polym Sci 2001;81:1572–80. https://doi.org/10.1002/app.1587.
54. [54] Gubler L, Prost N, Gürsel SA, Scherer GG. Proton exchange membranes prepared by radiation grafting of styrene/divinylbenzene onto poly (ethylene-alt-tetrafluoroethylene) for low temperature fuel cells. Solid State Ionics 2005;176:2849–60.
55. [55] Gubler L, Gürsel SA, Wokaun A, Scherer GG. Cross-linker effect in ETFE-based radiation-grafted proton-conducting membranes: I. Properties and fuel cell performance characteristics. J Electrochem Soc 2008;155:B921.
56. [56] Gubler L, Yamaki T, Sawada S, Gürsel SA, Wokaun A, Scherer GG. Cross-linker effect in ETFE-based radiation-grafted proton-conducting membranes: II. Extended fuel cell operation and degradation analysis. J Electrochem Soc 2009;156:B532.
57. [57] Yamaki T, Sawada S, Asano M, Maekawa Y, Yoshida M, Gubler L, et al. Fuel-cell performance of multiply-crosslinked polymer electrolyte membranes prepared by two-step radiation technique. ECS Trans 2009;25:1439.
58. [58] Sadeghi S, Işıkel Şanlı L, Güler E, Alkan Gürsel S. Enhancing proton conductivity via sub-micron structures in proton conducting membranes originating from sulfonated PVDF powder by radiation-induced grafting. Solid State Ionics 2018;314:66–73. https://doi.org/10.1016/j.ssi.2017.11.017.
59. [59] LaConti AB, Hamdan M, McDonald RC. Mechanisms of membrane degradation. Handb Fuel Cells 2010.
60. [60] Hübner G, Roduner E. EPR investigation of HO/radical initiated degradation reactions of sulfonated aromatics as model compounds for fuel cell proton conducting membranes. J Mater Chem 1999;9:409–18.
61. [61] Alkan Gürsel S, Yang Z, Choudhury B, Roelofs MG, Scherer GG. Radiation-Grafted Membranes Using a Trifluorostyrene Derivative. J Electrochem Soc 2006;153:A1964. https://doi.org/10.1149/1.2335626.
62. [62] Gubler L, Gürsel SA, Henkensmeier D, Wokaun A, Scherer GG. Novel ETFE based radiation grafted poly (styrene sulfonic acid-co-methacrylonitrile) proton conducting membranes with increased stability. Electrochem Commun 2009;11:941–4.
63. [63] Gupta B, Büchi FN, Scherer GG, Chapiro A. Materials research aspects of organic solid proton conductors. Solid State Ionics 1993;61:213–8.
64. [64] Büchi FN, Gupta B, Haas O, Scherer GG. Performance of differently cross‐linked, partially fluorinated proton exchange membranes in polymer electrolyte fuel cells. J Electrochem Soc 1995;142:3044.
65. [65] Gupta B, Scherer GG, Highfield JG. Thermal stability of proton exchange membranes prepared by grafting of styrene into pre‐irradiated FEP films and the effect of crosslinking. Die Angew Makromol Chemie 1998;256:81–4.
66. [66] Farquet P, Padeste C, Börner M, Gürsel SA, Scherer GG, Solak HH, et al. Microstructured proton-conducting membranes by synchrotron-radiation-induced grafting. J Memb Sci 2008;325:658–64.
67. [67] Curtin DE, Lousenberg RD, Henry TJ, Tangeman PC, Tisack ME. Advanced materials for improved PEMFC performance and life. J Power Sources 2004;131:41–8.
68. [68] Enomoto K, Takahashi S, Iwase T, Yamashita T, Maekawa Y. Degradation manner of polymer grafts chemically attached on thermally stable polymer films: Swelling-induced detachment of hydrophilic grafts from hydrophobic polymer substrates in aqueous media. J Mater Chem 2011;21:9343–9. https://doi.org/10.1039/c0jm04084c.
69. [69] Nasef MM, Saidi H. Structure-property relationships in radiation grafted poly(tetrafluoroethylene)-graft-polystyrene sulfonic acid membranes. J Polym Res 2005;12:305–12. https://doi.org/10.1007/s10965-004-5483-6.
70. [70] Kreuer KD. On the development of proton conducting polymer membranes for hydrogen and methanol fuel cells. J Memb Sci 2001;185:29–39. https://doi.org/10.1016/S0376-7388(00)00632-3.
71. [71] Saarinen V, Kallio T, Paronen M, Tikkanen P, Rauhala E, Kontturi K. New ETFE-based membrane for direct methanol fuel cell. Electrochim Acta 2005;50:3453–60. https://doi.org/10.1016/j.electacta.2004.12.022.
72. [72] Chuy C, Basura VI, Simon E, Holdcroft S, Horsfall J, Lovell K V. Electrochemical Characterization of Ethylenetetrafluoroethylene-g-polystyrenesulfonic Acid Solid Polymer Electrolytes. J Electrochem Soc 2000;147:4453. https://doi.org/10.1149/1.1394085.
73. [73] Kreuë KD. On the development of proton conducting materials for technological applications. Solid State Ionics 1997;97:1–15.
74. [74] Gubler L, Kuhn H, Schmidt TJ, Scherer GG, Brack HP, Simbeck K. Performance and durability of membrane electrode assemblies based on radiation-grafted FEP-g-polystyrene membranes. Fuel Cells 2004;4:196–207. https://doi.org/10.1002/fuce.200400019.
75. [75] Sanli LI, Tas S, Yürüm Y, Gürsel SA. Water free operated phosphoric acid doped radiation-grafted proton conducting membranes for high temperature polymer electrolyte membrane fuel cells. Fuel Cells 2014;14:914–25. https://doi.org/10.1002/fuce.201300110.
76. [76] Rosli RE, Sulong AB, Daud WRW, Zulkifley MA, Husaini T, Rosli MI, et al. A review of high-temperature proton exchange membrane fuel cell (HT-PEMFC) system. Int J Hydrogen Energy 2017;42:9293–314. https://doi.org/10.1016/j.ijhydene.2016.06.211.
77. [77] Wieser C. Novel polymer electrolyte membranes for automotive applications - Requirements and benefits. Fuel Cells 2004;4:245–50. https://doi.org/10.1002/fuce.200400038.
78. [78] Zhang J, Xie Z, Zhang J, Tang Y, Song C, Navessin T, et al. High temperature PEM fuel cells. J Power Sources 2006;160:872–91. https://doi.org/10.1016/j.jpowsour.2006.05.034.
79. [79] Song C, Tang Y, Zhang JL, Zhang J, Wang H, Shen J, et al. PEM fuel cell reaction kinetics in the temperature range of 23-120 °C. Electrochim Acta 2007;52:2552–61. https://doi.org/10.1016/j.electacta.2006.09.008.
80. [80] Chandan A, Hattenberger M, El-Kharouf A, Du S, Dhir A, Self V, et al. High temperature (HT) polymer electrolyte membrane fuel cells (PEMFC)-A review. J Power Sources 2013;231:264–78. https://doi.org/10.1016/j.jpowsour.2012.11.126.
81. [81] Bose S, Kuila T, Nguyen TXH, Kim NH, Lau KT, Lee JH. Polymer membranes for high temperature proton exchange membrane fuel cell: Recent advances and challenges. Prog Polym Sci 2011;36:813–43. https://doi.org/10.1016/j.progpolymsci.2011.01.003.
82. [82] Smitha B, Sridhar S, Khan AA. Solid polymer electrolyte membranes for fuel cell applications - A review. J Memb Sci 2005;259:10–26. https://doi.org/10.1016/j.memsci.2005.01.035.
83. [83] Schmidt C, Schmidt-Naake G. Proton conducting membranes obtained by doping radiation-grafted basic membrane matrices with phosphoric acid. Macromol Mater Eng 2007;292:1164–75. https://doi.org/10.1002/mame.200700188.
84. [84] Rajabalizadeh Mojarrad N, Sadeghi S, Yarar Kaplan B, Güler E, Alkan Gürsel S. Metal-Salt Enhanced Grafting of Vinylpyridine and Vinylimidazole Monomer Combinations in Radiation Grafted Membranes for High-Temperature PEM Fuel Cells. ACS Appl Energy Mater 2020;3:532–40. https://doi.org/10.1021/acsaem.9b01777.
85. [85] Güler E, Sadeghi S, Alkan Gürsel S. Characterization and fuel cell performance of divinylbenzene crosslinked phosphoric acid doped membranes based on 4-vinylpyridine grafting onto poly(ethylene-co-tetrafluoroethylene) films. Int J Hydrogen Energy 2018;43:8088–99. https://doi.org/10.1016/j.ijhydene.2018.03.087.
86. [86] Gottesfeld S, Dekel DR, Page M, Bae C, Yan Y, Zelenay P, et al. Anion exchange membrane fuel cells: Current status and remaining challenges. J Power Sources 2018;375:170–84. https://doi.org/10.1016/j.jpowsour.2017.08.010.
87. [87] Merle G, Wessling M, Nijmeijer K. Anion exchange membranes for alkaline fuel cells: A review. J Memb Sci 2011;377:1–35. https://doi.org/10.1016/j.memsci.2011.04.043.
88. [88] Poynton SD, Varcoe JR. Reduction of the monomer quantities required for the preparation of radiation-grafted alkaline anion-exchange membranes. Solid State Ionics 2015;277:38–43. https://doi.org/10.1016/j.ssi.2015.04.013.
89. [89] Wang L, Magliocca E, Cunningham EL, Mustain WE, Poynton SD, Escudero-Cid R, et al. An optimised synthesis of high performance radiation-grafted anion-exchange membranes. Green Chem 2017;19:831–43. https://doi.org/10.1039/c6gc02526a.
90. [90] Ponce-González J, Varcoe JR, Whelligan DK. Commercial Monomer Availability Leading to Missed Opportunities? Anion-Exchange Membranes Made from meta-Vinylbenzyl Chloride Exhibit an Alkali Stability Enhancement. ACS Appl Energy Mater 2018;1:1883–7. https://doi.org/10.1021/acsaem.8b00438.
91. [91] Poynton SD, Slade RCT, Omasta TJ, Mustain WE, Escudero-Cid R, Ocón P, et al. Preparation of radiation-grafted powders for use as anion exchange ionomers in alkaline polymer electrolyte fuel cells. J Mater Chem A 2014;2:5124–30. https://doi.org/10.1039/c4ta00558a.
92. [92] Biancolli ALG, Herranz D, Wang L, Stehlíková G, Bance-Soualhi R, Ponce-González J, et al. ETFE-based anion-exchange membrane ionomer powders for alkaline membrane fuel cells: A first performance comparison of head-group chemistry. J Mater Chem A 2018;6:24330–41. https://doi.org/10.1039/c8ta08309f.
93. [93] Sherazi TA, Yong Sohn J, Moo Lee Y, Guiver MD. Polyethylene-based radiation grafted anion-exchange membranes for alkaline fuel cells. J Memb Sci 2013;441:148–57. https://doi.org/10.1016/j.memsci.2013.03.053.
94. [94] Sherazi TA, Zahoor S, Raza R, Shaikh AJ, Naqvi SAR, Abbas G, et al. Guanidine functionalized radiation induced grafted anion-exchange membranes for solid alkaline fuel cells. Int J Hydrogen Energy 2015;40:786–96. https://doi.org/10.1016/j.ijhydene.2014.08.086.
95. [95] Espiritu R, Mamlouk M, Scott K. Study on the effect of the degree of grafting on the performance of polyethylene-based anion exchange membrane for fuel cell application. Int J Hydrogen Energy 2016;41:1120–33. https://doi.org/10.1016/j.ijhydene.2015.10.108.
96. [96] Wang L, Brink JJ, Liu Y, Herring AM, Ponce-González J, Whelligan DK, et al. Non-fluorinated pre-irradiation-grafted (peroxidated) LDPE-based anion-exchange membranes with high performance and stability. Energy Environ Sci 2017;10:2154–67. https://doi.org/10.1039/c7ee02053h.
97. [97] Wang L, Peng X, Mustain WE, Varcoe JR. Radiation-grafted anion-exchange membranes: The switch from low- to high-density polyethylene leads to remarkably enhanced fuel cell performance. Energy Environ Sci 2019;12:1575–9. https://doi.org/10.1039/c9ee00331b.
98. [98] Couture G, Alaaeddine A, Boschet F, Ameduri B. Polymeric materials as anion-exchange membranes for alkaline fuel cells. Prog Polym Sci 2011;36:1521–57. https://doi.org/10.1016/j.progpolymsci.2011.04.004.
99. [99] Subianto S, Pica M, Casciola M, Cojocaru P, Merlo L, Hards G, et al. Physical and chemical modification routes leading to improved mechanical properties of perfluorosulfonic acid membranes for PEM fuel cells. J Power Sources 2013;233:216–30. https://doi.org/10.1016/j.jpowsour.2012.12.121.
100. [100] Robertson NJ, Kostalik IV HA, Clark TJ, Mutolo PF, Abruña HD, Coates GW. Tunable high performance cross-linked alkaline anion exchange membranes for fuel cell applications. J Am Chem Soc 2010;132:3400–4. https://doi.org/10.1021/ja908638d.
101. [101] Dang HS, Weiber EA, Jannasch P. Poly(phenylene oxide) functionalized with quaternary ammonium groups via flexible alkyl spacers for high-performance anion exchange membranes. J Mater Chem A 2015;3:5280–4. https://doi.org/10.1039/c5ta00350d.
102. [102] Guo M, Fang J, Xu H, Li W, Lu X, Lan C, et al. Synthesis and characterization of novel anion exchange membranes based on imidazolium-type ionic liquid for alkaline fuel cells. J Memb Sci 2010;362:97–104. https://doi.org/10.1016/j.memsci.2010.06.026.
103. [103] Ponce-González J, Ouachan I, Varcoe JR, Whelligan DK. Radiation-induced grafting of a butyl-spacer styrenic monomer onto ETFE: The synthesis of the most alkali stable radiation-grafted anion-exchange membrane to date. J Mater Chem A 2018;6:823–7. https://doi.org/10.1039/c7ta10222d.
104. [104] Lu S, Pan J, Huang A, Zhuang L, Lu J. Alkaline polymer electrolyte fuel cells completely free from noble metal catalysts. Proc Natl Acad Sci U S A 2008;105:20611–4. https://doi.org/10.1073/pnas.0810041106.
105. [105] Komkova EN, Stamatialis DF, Strathmann H, Wessling M. Anion-exchange membranes containing diamines: Preparation and stability in alkaline solution. J Memb Sci 2004;244:25–34. https://doi.org/10.1016/j.memsci.2004.06.026.
106. [106] Xiong Y, Fang J, Zeng QH, Liu QL. Preparation and characterization of cross-linked quaternized poly(vinyl alcohol) membranes for anion exchange membrane fuel cells. J Memb Sci 2008;311:319–25. https://doi.org/10.1016/j.memsci.2007.12.029.
107. [107] Wang G, Weng Y, Chu D, Xie D, Chen R. Preparation of alkaline anion exchange membranes based on functional poly(ether-imide) polymers for potential fuel cell applications. J Memb Sci 2009;326:4–8. https://doi.org/10.1016/j.memsci.2008.09.037.
108. [108] Zhou T, Shao R, Chen S, He X, Qiao J, Zhang J. A review of radiation-grafted polymer electrolyte membranes for alkaline polymer electrolyte membrane fuel cells. J Power Sources 2015;293:946–75. https://doi.org/10.1016/j.jpowsour.2015.06.026.