Preparation of an Anion Exchange Membrane by Pyridine-Functionalized Polyether Ether Ketone To Improve Alkali Resistance Stability for an Alkali Fuel Cell
Yongjiang Yuan, Tingyu Zhang, Zhe Wang
Abstract
A highly stable anion exchange membrane (AEM) is constructed by linking bipyridine to a polyetheretherketone (PEEK) polymer. First, PEEK is prepared by the polycondensation reaction; N-bromosuccinimide and benzoyl peroxide are used for the bromination reaction; and then pyridine or 4,4′-bipyridine is connected to PEEK by the Friedel–Crafts alkylation reaction. The successful preparation of the target product was confirmed by the collaborative analysis of the Fourier transform infrared spectrum and 1H nuclear magnetic resonance spectrum. The ionic conductivity test showed that the highest hydroxide conductivity of PyBPEEK-50% and BiPyBPEEK-50% at 80 °C reached 36.99 and 32.05 mS cm–1, respectively, which proved that they can meet the basic requirements. The alkali stability test showed that the ionic conductivity of the membrane could still reach 88.46% after 750 h of immersion in 1 M NaOH at room temperature, which proved that the cross-linking structure composed of 4,4′-bipyridine effectively weakened the attack of OH– on AEMs. In addition, the cross-linked structure effectively balances the loss of mechanical properties as a result of water absorption and membrane swelling. The swelling rate of BiPyBPEEK-50% at 80 °C is only 4.4%, and the tensile strength can reach 66 MPa. Therefore, to avoid the introduction of too many uncontrollable factors in the complicated synthesis process, this work used a simple method to synthesize AEMs based on the bipyridine cross-linked structure and compared its performance gains and losses through non-cross-linked membranes. The potential application value of this method in the field of fuel cells is verified.