Double network anion exchange membrane with excellent flexibility and stability

Abstract

A double-network anion exchange membrane (TA/AT-PEK/PVA-x) was prepared by Br-PEK and PVA, 3-amino-1,2,4 triazole forms a cross-linking structure with PVA under the action of 1,4-phthalaldehyde and then triazole can be linked with Br-PEK. The structure of membranes was verified by FT-IR. The composite membrane is uniform and smooth can be seen from the scanning electron microscope (SEM) and exhibit good hydrophilic/hydrophobic micro-phase separation structure proved by Transmission electron micrograph (TEM). The ionic conductivity of TA/AT-PEK/PVA-0.15 is 0.062 S/cm at 80 °C. With the addition of PVA within a certain range, the water uptake, swelling ratio hydroxide conductivity and alkaline stability are increase. The membranes are more flexible. After immersing in 4 M NaOH solutions for 240 h at 80 °C, it remains at least 65% of its initial hydroxide ion conductivity of TA/AT-PEK/PVA-0.3 membrane. With the increasing number of water molecules solvating the hydroxide, its nucleophilicity and basicity were hindered, which enhance alkaline stability of anion exchange membranes.