Rigid-Rod Poly(phenylenesulfonic acid) Proton Exchange Membranes with Cross-Linkable Biphenyl Groups for Fuel Cell Applications

    Authors

    K. Si; R. Wycisk; D. X. Dong; K. Cooper; M. Rodgers; P. Brooker; D. Slattery;M. Litt

    Comments

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    Abbreviated Journal Title

    Macromolecules

    Keywords

    POLYMER ELECTROLYTE MEMBRANES; HUMIDITY FIXED-POINTS; HIGH-CONDUCTIVITY; POLYBENZIMIDAZOLES; TEMPERATURE; POLYIMIDES; STABILITY; NAFION; PEMS; Polymer Science

    Abstract

    Biphenyl was grafted on rigid-rod aromatic poly(p-phenylenesulfonic acids) (IEC similar to 8 mequiv g(-1)) to generate cross-linkable polyelectrolytes. Cross-linking conditions and film properties before and after cross-linking were studied. Films equilibrated between 20 and 30% relative humidity (RH) had tensile moduli of 2 to 1 GPa and broke at 5 to 9% elongation. The moduli decreased as RH increased and dropped drastically at high humidity if the films were not cross-linked. Grafted films had conductivities at 80 degrees C 4-5 times that of Nafion NR-212 over the whole relative humidity range even after cross-linking. The sample reported in detail here had a conductivity of 0.10 S cm(-1) at 120 degrees C and 30% RH. As is usual for this class of materials, even after the loss of 24% of starting sulfonic acid groups by grafting and cross-linking, ionic conductivity was high at low humidity. A membrane electrode assembly (MEA) prepared with this rigid-rod poly(phenylenesulfonic acid) proton exchange membrane and tested in a fuel cell exhibited performance and properties similar to those of Nafion NR-212 films. The power density was similar to 95% of that of the Nafion MEA over the operating range in spite of relatively high hydrogen crossover due to the presence of nanocracks in the membrane.

    Journal Title

    Macromolecules

    Volume

    46

    Issue/Number

    2

    Publication Date

    1-1-2013

    Document Type

    Article

    Language

    English

    First Page

    422

    Last Page

    433

    WOS Identifier

    WOS:000314081800011

    ISSN

    0024-9297

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