Synthesis and properties of chemically cross-linked poly(vinyl alcohol)–poly(acrylamide-co-diallyldimethylammonium chloride) (PVA–PAADDA) for anion-exchange membranes

Alkaline anion-exchange membranes were prepared from poly(vinyl alcohol) and poly(acrylamide-co-diallyldimethylammonium chloride) by blending, then chemical cross-linking using glutaraldehyde as the cross-linking agent (PVA–PAADDA–GA). Membranes were characterized by Fourier-transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). OH− conductivities in the range of 7.7 × 10− 4–3.03 × 10− 3 S cm− 1 were obtained for PVA–PAADDA–GA membranes at room temperature (23 ± 2 °C) along with the IEC values changed from 0.91 to 1.63 mequiv g− 1. The temperature dependences of OH− conductivities followed the Arrhenius relationship at a temperature range from 20 to 90 °C. The apparent activation energy for OH− conduction was in the range of 15–19 kJ mol− 1 depending on PAADDA content in the polymer. High alkaline stability of PVA–PAADDA–GA membranes was retained after conditioning in 6.0 M KOH at 80 °C for 24 h. Also, the membranes showed excellent dimensional stability in both hot water and hot methanol solutions at 90 °C. Although a relatively high water uptake (more than 2-fold of Nafion 115), the PVA–PAADDA–GA membranes showed excellent methanol resistance with the methanol permeability ranged from 2.85 to 4.16 × 10− 7 cm2 s− 1, which were 5 ~ 6 times lower than that of the Nafion 115.