Imidazolium functionalized poly(vinyl alcohol) membranes for direct methanol alkaline fuel cell applications

Abstract

In this study, imidazolium functionalized poly(vinyl alcohol) (PVA) was synthesized by acetalization and direct quaternization reaction. Afterwards, composite anion exchange membranes based on imidazolium-and quaternary ammonium-functionalized PVA were used for direct methanol alkaline fuel cell applications. 1 H NMR and Fourier transform infrared spectroscopy data indicated that imidazole functionalized PVA was successfully synthesized. Inductively coupled plasma mass spectrometry data demonstrated that the imidazolium structure was efficiently obtained by direct quaternization of the imidazole group. Composite anion exchange membranes were fabricated by application of the functionalized PVA solution on the surface of porous polycarbonate (PC) membranes. Fuel cell related properties of all prepared membranes were investigated systematically. The imidazolium functionalized composite membrane (PVA-Im/PC) exhibited higher ionic conductivity (7.8 mS cm −1 at 30°C) despite a lower water uptake and ion exchange capacity value compared to that of quaternary ammonium. In addition, PVA-Im/PC showed the lowest methanol permeation rate and the highest membrane selectivity as well as high alkaline and oxidative stability. Dynamic mechanical analysis results reveal that both composite membranes were mechanically resistant up to 10 7 Pa at 140°C. The superior performance of imidazolium functionalized PVA composite membrane compared to quaternary ammonium functionalized membrane makes it a promising candidate for direct methanol alkaline fuel cell applications.

Different cationic functionalized epichlorohydrin modified polyvinyl alcohol based anion exchange membrane

“…2950 and 2873 cm −1 are ascribed to the CH stretching. In Figure 3b, ~1647 cm −1 is ascribed to the CN stretching, ~1453 cm −1 is ascribed to the CN stretching, and ~758 cm −1 is ascribed to the bending vibration of imidazole ring 28 . These prove the existence of imidazole group in EPMIAC.…”

“…In Figure 3d–j all have absorption peaks at 3500–3000 cm −1 , 2944–2849 cm −1 , 1415 cm −1 and 1090 cm −1 , which are ascribed to the OH stretching, CH stretching, CH bending vibration and CO stretching in the PVA matrix, respectively 28 . Compared with the pure PVA, the F‐PVA AEMs add COC bonds and three different cations, and the peaks at ~1474 cm −1 and ~1036 cm −1 are added in Figure 3e–g than in Figure 3d, which just correspond to the CN stretching and COC stretching, 25,28,30 thus proving that the graft of PVA is successful.…”

“…In Figure 3d–j all have absorption peaks at 3500–3000 cm −1 , 2944–2849 cm −1 , 1415 cm −1 and 1090 cm −1 , which are ascribed to the OH stretching, CH stretching, CH bending vibration and CO stretching in the PVA matrix, respectively 28 . Compared with the pure PVA, the F‐PVA AEMs add COC bonds and three different cations, and the peaks at ~1474 cm −1 and ~1036 cm −1 are added in Figure 3e–g than in Figure 3d, which just correspond to the CN stretching and COC stretching, 25,28,30 thus proving that the graft of PVA is successful. In Figure 3e, ~933 cm −1 is ascribed to the characteristic absorption of cyclic quaternary ammonium salt, 23,26 which proves the existence of piperidine group; in Figure 3f, ~1659 cm −1 is ascribed to the CN stretching, ~786 cm −1 is ascribed to the bending vibration of imidazole ring, 24,28 both of which prove the existence of imidazole group; in Figure 3g, 954 cm −1 is ascribed to the characteristic absorption of quaternary ammonium group, 29 which proves the existence of trimethylammonium group.…”

Poly(vinyl alcohol)‐based membranes for fuel cell and water treatment applications: A review on recent advancements

“…For examples, most of the PVA modification reactions involve etherification, 17,18 esterification, 19,20 and acetalization 21,22 via hydroxyl groups. Besides that, sulfonation, 23,24 phosphorylation, 19,25,26 imidization, 27 amination, 28 quaternization, 17,29 azidation, 28 and complexation 30 have also been explored to introduce specific functional groups. In addition, water has been used as a reaction medium for click reaction of imidized‐PVA with porpargylamine, 28 and functionalized graphene oxide 31 to obtain amine‐functionalized PVA and graphene oxide (GO)‐grafted‐PVA respectively.…”

Dual Cross-Linked Poly(vinyl alcohol)-Based Anion Exchange Membranes with High Ion Selectivity for Vanadium Flow Batteries

“…7,39 Due to the presence of hydroxyl groups, PVA can be modified by an aldehyde compound through the acetal functionalization. Several PVA derivatives have been successfully synthesized by using 4-dimethylaminobenzaldehyde, 40,41 4-formyl-1-methylpyridinium, 42 1-methyl-2-imidazolecarboxaldehyde, 43 imidazole-4-carbaldehyde, 44 4-imidazolyl benzaldehyde, 45 and 4-(bromomethyl)benzaldehyde 46 as acetalization reagents. Based on the above concept, tertiary amine group functionalized PVA (i.e., poly(vinyl acetal) (PVAc)) was first synthesized via the acetalization reaction between 4-dimethylaminobenzaldehyde (DMABA) and PVA in the present work.…”