Transition-metal-free preparation of polyethylene-based anion exchange membranes from commercial EVA

Abstract

Anion exchange membranes (AEMs) bearing polyethylene (PE) backbones have general advantages of outstanding chemical stability, balanced rigidity and toughness, good compatibility with various ionic functional groups, and aromatic-free structures. However, previous preparation of aromatic-free PE-based AEMs relies on complicated monomer synthesis and noble transition-metal catalysts (for metathesis, hydrogenation, coordinative polymerization, etc.). We herein propose a novel approach using commercial poly(ethylene-co-vinyl acetate) (EVA) to conveniently produce a series of trimethylammonium- and piperidinium-functionalized PE-based AEMs. The synthetic process involves Mitsunobu derivatization to form amine-functionalized PE intermediates without the use of any transition-metal catalysts. The resultant AEMs have high hydroxide conductivities (up to 129 mS/cm at 80 °C), good alkaline stability in 5 M KOH at 60 °C for 30 days, and promising AEM water electrolysis performance.