Relative Chemical Stability of Imidazolium-Based Alkaline Anion Exchange Polymerized Ionic Liquids

We thoroughly investigate and quantify the chemical stability of an imidazolium-based alkaline anion exchange polymerized ionic liquid (PIL), poly(1-[(2-methacryloyloxy)ethyl]-3-butylimidazolium hydroxide) (poly(MEBIm-OH), over a broad range of humidities, temperatures, and alkaline concentrations using the combined techniques of electrochemical impedance spectroscopy and nuclear magnetic resonance spectroscopy. High chemical stability was observed under dry conditions (10% RH) at 30 °C, humid and saturated conditions up to 80 °C, and even in mild alkaline conditions ([KOH] 1 M). Under these conditions, we suggest an imidazolium ring-opening mechanism as the primary degradation pathway, based on a detailed analysis of the 1H NMR spectra. Similar to poly(MEBIm-OH), other alkaline anion (carbonate (CO32–) and bicarbonate (HCO3–)) exchange PILs were als...

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