Anion conductive membrane performance facilitation via tethering flexible with rigid backbones using oscillational chain

Abstract

Herein, a novel strategy to improve the performance of anion exchange membranes (AEMs) is adopted to build a crosslinked structure by tethering the rigid poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) backbone and the flexible poly(4-vinylphenol) (PVP) backbone using an oscillational chain. The incompatibility between the PPO and PVP backbones makes them self-aggregated resulting in occurrence of distinct microphase separation and development of ion transport channels in the AEMs to facilitate the transport of hydroxide ion. The microphase separation of the as-prepared AEMs has been revealed by transmission electron microscopy (TEM) and DI multimode atomic force microscopy (AFM). The existence of the hydrophilic PVP chain also ensures sufficient water uptake to enhance the conductivity of the AEMs. A maximum ionic conductivity of 134 mS cm−1 is achieved at 80 °C by the PPO-c-PVP-40% (40% is the molar content of PVP chains) membrane. A maximum power density of 173 mW cm−2 at 80 °C is obtained by a H2/O2 single cell using the PPO-c-PVP-40% membrane electrode assembly. The PPO-c-PVP-40% membrane also exhibits robust alkaline stability (retains about 90% ionic conductivity after 480 h alkaline stability test) and excellent mechanical property. Those render the AEMs a potential membrane electrode material for fuel cell applications.