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Sulfonated (poly)arenes as low-humidity proton conducting materials for polymer electrolyte fuel cell membrane applications

Garanin, Evgeny M.
http://rave.ohiolink.edu/etdc/view?acc_num=kent1310582597

Abstract Details

2011, PHD, Kent State University, College of Arts and Sciences / Department of Chemistry.
Block-copolymers with highly sulfonated ionomer blocks are considered as the main candidates for low-humidity high-temperature Polymer Electrolyte Fuel Cell membranes. We present synthetic routes to polyphenylene sulfide (PPS) with a degree of sulfonation (DOS) equal to 1 and to poly(thio-2,5-difluoro-1,4-phenylene). In the future, these polymers can be used as hydrophilic and hydrophobic blocks in polyphenylene sulfide based proton conducting membranes. PPS DOS=1 was synthesized via acid-catalyzed oxidative polymerization of sulfonated 2-(methylsulfinyl)-5-(2-sulfonatophenylthio)benzenesulfonate derivatives. The sulfonated monomers used in this work were prepared from benzenesulfonic acid in 5 to 8 steps. Acid and thermally stable poly(2,5-difluorophenylene sulfide) and poly((((methylsulfonio)-2,5-difluoro-1,4-phenylene)thio)-2,5-difluoro-1,4-phenylene triflate), were successfully derived from 4-(methylsulfinyl)-2,5-difluorophenyl 2,5-difluorophenyl sulfide. The resulting polymers were characterized by FTIR, NMR, TGA and DSC. The number-average molecular weight of poly((((methylsulfonio)-2,5-difluoro-1,4-phenylene)thio)-2,5-difluoro-1,4-phenylene triflate) was studied by 1H NMR spectroscopy and exceeded 20000 Da. 4-(Methylsulfinyl)-2,5-difluorophenyl 2,5-difluorophenyl sulfide was made via an efficient multistep synthesis from 1,4-difluorobenzene. Poly(2,5-difluorophenylene sulfide) is a promising candidate as a non-sulfonated block of future multiblock copolymers. Additionally we report the crystal structures, synthesis, water sorption isotherms, proton conductivity, thermal stabilities and XRD studies, of benzenehexasulfonic acid (BHSA) and benzenetetrasulfonic acid (BTSA), model systems for highly sulfonated polyphenylenes. At comparable humidities and temperatures, BHSA material shows conductivity similar to Nafion which conducts protons via liquid water channels. The conductivity of BTSA is in the range of 108 -104 S/cm. Thermal stability studies on BHSA revealed that it forms unusually stable cyclic benzenehexasulfonic acid-1,2; 4,5-dianhydride and (most likely) benzenehexasulfonic acid-1,2;3,4-dianhydride which, upon prolonged standing in solution, transforms to benzenehexasulfonic acid-1,2-monoanhydride. The mono- and dianhydrides do not hydrolyze readily due to their flatter, more aromatic structures compared to the hydrolysis products. The anhydrides undergo unusual ring-shift isomerization, which is pronounced on the NMR time scale. Additionally, we have disclosed here previously unknown crosslinking that occurs with polyphenylene sulfide with DOS=0.7 at elevated temperatures. Valuable conductivity data are obtained with a novel cell that utilizes a four electrode method for conductivity measurements in powder samples
Paul Sampson (Advisor)
Polymer Chemistry

Recommended Citations

Citations

  • Garanin, E. M. (2011). Sulfonated (poly)arenes as low-humidity proton conducting materials for polymer electrolyte fuel cell membrane applications [Doctoral dissertation, Kent State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=kent1310582597

    APA Style (7th edition)

  • Garanin, Evgeny. Sulfonated (poly)arenes as low-humidity proton conducting materials for polymer electrolyte fuel cell membrane applications. 2011. Kent State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=kent1310582597.

    MLA Style (8th edition)

  • Garanin, Evgeny. "Sulfonated (poly)arenes as low-humidity proton conducting materials for polymer electrolyte fuel cell membrane applications." Doctoral dissertation, Kent State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=kent1310582597

    Chicago Manual of Style (17th edition)

kent1310582597
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© 2011, all rights reserved.
This open access ETD is published by Kent State University and OhioLINK.