Low equivalent weight Friedel-Crafts cross-linked sulfonated poly(ether ether ketone)

    Authors

    Slnh Rhoden; C. A. Linkous; N. Mohajeri; D. J. Diaz; P. Brooker; D. K. Slattery;J. M. Fenton

    Comments

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    Abbreviated Journal Title

    J. Membr. Sci.

    Keywords

    SPEEK; Benzenedimethanol; Cross-linked; Friedel-Crafts; Polymer; Membrane; ELECTROLYTE FUEL-CELLS; COMPOSITE MEMBRANES; WATER-UPTAKE; THERMAL-STABILITY; IONOMER MEMBRANES; SPEEK; STATE; CONDUCTIVITY; POLYSTYRENE; TEMPERATURE; Engineering, Chemical; Polymer Science

    Abstract

    Poly(ether ether ketone) (PEEK) was sulfonated by electrophillic aromatic substitution to produce a highly water soluble polymer. With an equivalent weight (EW) of 381 g/eq, the polymer is capable of a proton conductivity of 0.2 S/cm at 80 degrees C and 100% relative humidity (RH). High proton conductivity in polymer electrolyte membranes is a key factor for optimum hydrogen fuel cell performance. Under testing at saturating RHs, the highly sulfonated polymer absorbs water while simultaneously becoming swollen and mechanically weak. To maintain mechanical stability, a ZnCl(2) catalyst was used to catalyze a Friedel-Crafts-type cross-linking using benzenedimethanol(BDM) as cross-linking agent. Although membrane thermal properties did not improve substantially, solubility was decreased and mechanical strength increased. Membranes cross-linked with 12 and 24 wt.% BDM yielded polymers with equivalent weights of 395 and 416 g/eq and conductivities of 0.15 and 0.14 S/cm at 80 degrees C and 100% RH, respectively, without excessive water uptake shown by the pure 96% sulfonated PEEK. Characterization of the pure and cross-linked membranes were also studied using Fourier transform infrared spectroscopy, water uptake, thermogravimetric coupled mass spectrometry and differential scanning calorimetry. Membranes were covered with platinum on carbon catalyst ink, and further characterized using linear sweep voltammetry. Behavior comparable to perfluoroalkyl sulfonate ionomers was demonstrated. (C) 2011 Elsevier B.V. All rights reserved.

    Journal Title

    Journal of Membrane Science

    Volume

    376

    Issue/Number

    1-2

    Publication Date

    1-1-2011

    Document Type

    Article

    Language

    English

    First Page

    290

    Last Page

    301

    WOS Identifier

    WOS:000292437600033

    ISSN

    0376-7388

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