Fabricating hydroxyl anion conducting membranes based on poly(vinyl alcohol) and bis(2-chloroethyl) ether-1,3-bis[3-(dimethylamino)propyl] urea copolymer with linear anion-exchange sites for polymer electrolyte membrane fuel cell

This study focused on the design and fabricating of a new type of hydroxyl anion conducting membranes employing the interpenetrating polymer network (IPN) comprising poly (vinyl alcohol) (PVA) and linear structured poly bis(2-chloroethyl) ether-1,3-bis [3-(dimethylamino)propyl] urea copolymer (PUB). The membranes are synthesized through blending assisted by a simple chemical cross-linking process. Various characterizations are conducted including Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), gravimetric analysis (TG), X-ray photoelectron spectroscopy (XPS) and AC impedance. Results revealed that by simply tuning the mass fraction of PUB (the content of PUB changed from 20%-50%) in the membrane, the OH- conductivity (10− 2 S cm− 1 at 80 °C, fully hydrated membranes) with high extensibility (at break in the range of 200-400%) and tensile stress (at break around 15-30 MPa, ∼ 50% relative humidity) are achieved. XPS analysis reveals that a slight degradation occurs when the membrane is exposed to exceedingly tough conditions such as 8 M KOH at 80 °C for 240 h, but the OH- conductivity is changed insignificantly. When assembled in a real H2/O2 alkaline fuel cell, the initial peak power densities in the range of 5.7-28.6 mW cm− 2 and an open circuit potential reaching to 1.0 V are obtained for MEAs fabricated with these membranes at 25 °C.