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

Abstract

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 (10−2Scm−1 at 80°C, fully hydrated membranes) with high extensibility (at break in the range of 200–400%) and tensile stress (at break around 15–30MPa, ∼50% relative humidity) are achieved. XPS analysis reveals that a slight degradation occurs when the membrane is exposed to exceedingly tough conditions such as 8M KOH at 80°C for 240h, 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 5.7–28.6mWcm−2 and an open circuit potential reaching to 1.0V are obtained for MEAs fabricated with these membranes at 25°C.