Angela Mohanty - Stable Elastomeric Anion Exchange Membranes Based on Quaternary Ammonium-Tethered SEBS Triblock Copolymers

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      Publication Details (including relevant citation   information):

         

    Mohanty, A.D.; Kim, Y.S.; and Bae, C., Stable Elastomeric Anion Exchange Membranes Based on Quaternary Ammonium-Tethered SEBS Triblock Copolymers,Macromolecules, 2015, 48, 7085

      Abstract:

     A chemically stable and elastomeric triblock copolymer, polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene

    (SEBS), was functionalized with various benzyl- and alkyl-substituted quaternary ammonium (QA) groups for anion exchange

    membrane (AEM) fuel cell applications. Synthetic methods involving transition metal-catalyzed CH borylation and Suzuki

    coupling were utilized to incorporate six diff erent QA structures to the polystyrene units of SEBS. Changes in AEM properties as

    a result of diff erent QA moieties and chemical stability under alkaline conditions were investigated. Anion exchange polymers

    bearing the trimethylammonium pendants, the smallest QA cation moiety, exhibited the most signifi cant changes in water uptake

    and block copolymer domain spacing to off er the best ion transport properties. It was demonstrated that incorporating stable

    cation structures to a polymer backbone comprising solely CH and CC bonds resulted in AEM materials with improved longterm

    alkaline stability. After 4 weeks in 1 M NaOH at 60 and 80  ° C, SEBS-QA AEMs remained chemically stable.   Fuel cell tests

    using benzyltrimethylammonium-containing SEBS (SEBS-TMA) as an AEM demonstrated excellent performance, generating

    one of the best maximum power density values and lowest ohmic resistance with low Pt catalyst loaded electrode reported thus

       

    far. Both polymer backbone and cation functional group remained stable after 110 h lifetime test at 60 °C.

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