Alkaline stability of ether bond free fluorene-based anion exchange polymer containing cycloaliphatic quaternary ammonium groups

Quaternary piperidinium cation was incorporated into aryl-ether-bond-free fluorene-based polymer by flexible alkyl side chains to synthesize a highly conductive and chemically stable anion exchange membrane (AEM). The membrane of the OH− form shows good solubility in dimethyl sulfoxide and methanol but not soluble in water. In a fully hydrated state, the OH− conductivity reached 58 mS cm−1 at 80 °C. The results of 1H NMR spectra revealed that the alkyl-substituted N-methylpiperidinium cationic group was excellent alkaline stable as only 13% cationic group was degraded after 168 h storage in 1 M NaOH solution at 80 °C.