Electrodialytic Transport Properties of Anion-Exchange Membranes Prepared from Poly(vinyl alcohol) and Poly(vinyl alcohol-co-methacryloyl aminopropyl trimethyl ammonium chloride)

Abstract: Random-type anion-exchange membranes (AEMs) have been prepared by blending poly(vinyl alcohol) (PVA) and the random copolymer-type polycation, poly(vinyl alcohol-co-methacryloyl aminopropyl trimethyl ammonium chloride) at various molar percentages of anion-exchange groups to vinyl alcohol groups, C_pc, and by cross-linking the PVA chains with glutaraldehyde (GA) solution at various GA concentrations, C_GA. The characteristics of the random-type AEMs were compared with blend-type AEMs prepared in our previous study. At equal molar percentages of the anion exchange groups, the water content of the random-type AEMs was lower than that of the blend-type AEMs. The effective charge density of the random-type AEMs increased with increasing C_pc and reached a maximum value. Further, the maximum value of the effective charge density increased with increasing C_GA. The maximum value of the effective charge density, 0.42 mol/dm³, was obtained for the random-type AEM with C_pc = 4.2 mol % and C_GA = 0.15 vol %. A comparison of the random-type and blend-type AEMs with almost the same C_pc showed that the random-type AEMs had lower membrane resistance than the blend-type ones. The membrane resistance and dynamic transport number of the random-type AEM with C_pc = 6.0 mol % and C_GA = 0.15 vol % were 4.8 Ω cm² and 0.83, respectively.