Anion-conducting ionomers: Study of type of functionalizing amine and macromolecular cross-linking

Anion exchange membranes (AEM) were prepared by chloromethylation and amination of polysulfone (PSU) and polyphenylsulfone (PPSU). The reaction pathways were studied by 1H and 13C NMR spectroscopy and ab-initio calculations. Various amines were used, including trimethylamine (TMA), 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) and 1,4-diazabicyclo[2.2.2]octane (DABCO) to study the influence of the molecular volume and the stabilizing effect of a delocalization of the positive ammonium ion charge on a second nitrogen. Furthermore, the effect of a solvothermal cross-linking on the stability of AEM was investigated. The alkaline stability, measured after treatment in 2 M KOH at 60 °C during 168 h, is improved by DBN and polymer reticulation. The ionic conductivity in water reaches values above 10 mS/cm with DABCO. The hydroxide ion mobility depends linearly on the hydration number.