Utilizing thiol-ene chemistry for crosslinked nickel cation-based anion exchange membranes

Metal cation-based anion exchange membranes (AEMs) are a unique class of materials that have shown potential to be highly stable AEMs with competitive conductivities. Here, we expand upon previous work to report the synthesis of crosslinked nickel cation-based AEMs formed using the thiol-ene reaction. These thiol-ene-based samples were first characterized for their morphology, both with and without nickel cations, where the nickel-containing membranes demonstrated a disordered scattering peak characteristic of ionic clusters. The samples were then characterized for their water uptake, chemical and mechanical stability, and conductivity. They showed a combination of high water content and extreme brittleness, which also resulted in fairly low conductivity. The brittleness resulted from large water swelling as well as the need for each nickel cation to act as a crosslinker, necessary with the current nickel-coordination chemistry. Therefore, increasing the ion exchange capacity (IEC) for these types of AEMs, important for enhancing conductivity, also increased the crosslink density. The low conductivity and brittleness seen in this work demonstrated the need to develop non-crosslinking metal-complexes. (c) 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 328-339