Dependable polysulfone based anion exchange membranes incorporating triazatriangulenium cations

A convenient approach for the fabrication of robust anion exchange membranes designed for electrochemical applications is presented. A triazatriangulenium carbocation (i.e., 4,8,12-tri-ethano-4,8,12-triazatriangulenium tetrafluoroborate) with a pK_R+ above 20 was used as hydroxide anion and negative charge carrier in polysulfone anion exchange membranes. Morphological analysis of these membranes using high resolution scanning electron microscopy (HRSEM) and small angle X-ray scattering (SAXS) confirmed a phase separation casting process resulting in electrolyte exposed cations. It appears that 4,8,12-tri-ethano-4,8,12-triazatriangulenium brings about an extensive carbocation network within the polysulfone matrix, allowing smooth transport of hydroxide anions with low activation energy value (6.56 kJ mol⁻¹), substantial ion conductivity (23.5 mS cm⁻¹ at 90 °C), and good ion exchange capacity (2.44 ± 072 meq/g). The high stability of the triazatriangulenium cation contributes to the retention of 88% of the initial membrane conductivity for the tested period of 35 days at 60 °C in a 3 M KOH solution. This class of unique carbocations serve as a model system for stable charge carriers in alkaline exchange membranes for electrochemicaltio applications.