Benzylmethyl-containing poly(arylene ether nitrile) as anion exchange membranes for alkaline fuel cells

A series of novel quaternized benzylmethyl-containing poly(arylene ether nitrile)s (QPENs) were synthesized via condensation polymerization, bromination and quaternization. N,N,N',N'-tetramethyl-1,6-cliaminohexane dissolved in isopropanol was used as the quaternization reagent for the preparation of target anion exchange membranes (AEMs) H-1 NMR spectroscopy, Fourier transform infrared spectroscopy (FT-IR) and gel permeation chromatography (CPC) were used to characterize the as synthesized copolymers. The ratio of hydrophilic to hydrophobic segment on the polymer backbone was varied to study the structure property of the AEMs. With strong nitrite dipole interchain interactions and a self-crosslinked structure, the resulting AEMs possess a self-anti-swelling property resulting in a low water uptake and swelling ratio. The AEMs show high ionic conductivity (under hydrated conditions) above the magnitude of 10(-2) S cm(-1). The membranes with distinct phase separation morphology have a higher ionic exchange capacity (IEC). The methanol permeability of the AEMs in the range 3.18-9.69 x 10(-8) cm(2) s(-1) at 30 degrees C and 8.92-25.57 x 10(-8) cm(2) s(-1) at 60 degrees C is lower than that of Nafion (R) 117. The AEMs show an excellent alkaline stability in a 2 M NaOH solution at 60 degrees C for 1080 h. A single cell with the QPEN membrane shows an open circuit voltage of 0.84 V. A maximum power density of 79.1 mW cm(-2) at a current density of 207 mA cm(-2) can be achieved at 60 degrees C. In summary the AEMs are good candidates for evaluation in fuel cells. (C) 2015 Elsevier B.V. All rights reserved.