Feng, Zhiming and Esteban, Pilar and Gupta, Gaurav and Fulton, David and Mamlouk, Mohamed (2021) Highly conductive partially cross-linked poly(2,6-dimethyl-1,4-phenylene oxide) as anion exchange membrane and ionomer for water electrolysis. International Journal of Hydrogen Energy, 46 (75). pp. 37137-37151. ISSN 0360-3199
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Abstract
Cross-linked quaternised Poly(2,6-dimethyl-1,4-Phenylene Oxide) (QPPO)-based membranes were prepared via Friedel-Crafts reactions using SnCl4 catalyst, 1,3,5-trioxane and chlorotrimethylsilane as environmentally-friendly chloromethylating reagents. New equations to calculate the degree of chloromethylation (DC) and cross-linking degree (CLD) were proposed. Ionic conductivity of 133 mS cm−1 at 80 °C was obtained, one of the highest reported for QPPO based membranes. We have compared QPPO to chloromethylated polystyrene-b-poly(ethylene/butylene)-b-polystyrene (SEBS) ionomer and report on the importance of ionomer-membrane interaction as well as the trade-off between swelling ratio and conductivity on performance and mechanical stability of AEM water electrolyser. Exsitu stability testing after 500 h in 1 M KOH showed membranes retained up to 94% of their original IEC. QPPO was employed as both membranes and ionomers in electrolyser tests. QPPO membranes exhibited area specific resistance of 104 mΩ cm−2 and electrolyser current density of 814 mA cm−2 at 2.0 V in 0.1 M NaOH solution at 40 °C.