Polystyrene‐based anion exchange membranes via click chemistry: improved properties and AEM performance

Abstract

Polystyrene-based anion exchange membranes (AEMs) have been fabricated using in situ click chemistry between azide and alkyne moieties introduced as side groups on functionalized polymers. The membrane properties such as water uptake, swelling ratio and conductivity were affected by the number of cations and the degree of crosslinking. The membranes containing a larger amount of trimethylammonium cationic groups (i.e. higher ion exchange capacity) showed high hydroxide conductivity when immersed in KOH solution, exhibiting a peak in conductivity (156 mS cm −1 ) in 3 mol L -1 KOH solution. A higher degree of crosslinking tended to decrease conductivity. These membranes demonstrated relatively good stability in 8 mol L -1 KOH at 60 ∘ C and maintained 33%-62% of initial conductivity after 49 days with most of the loss in conductivity occurring in early stages of the test. In an alkaline fuel cell, the areal specific resistance was constant indicating good stability of the membranes. The observed peak power density (157 mW cm −2 ) was comparable to that of other AEM-based fuel cells reported.

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

“…When the ionic conductivities of the membranes were compared in terms of cast and composite structure, the PVA‐QAm/PC membrane exhibited a higher conductivity than the PVA‐QAm cast membrane, whereas the PVA‐QAm cast membrane had a higher IEC value. This result is the opposite of the generally accepted assumption that higher IEC and water uptake value result in higher ionic conductivity 40 . Our conductivity results affirm that a high IEC and water uptake value are not the primary indicative factors for high ionic conductivity.…”

Rational molecular design of anion exchange membranes functionalized with alicyclic quaternary ammonium cations

“…Polymer backbone degradation in AEMs has primarily been observed to occur via aryl ether bonds cleavage, [13][14][15][16][17][18] motivating a recent change in research focus towards aryl-ether free backbones 19 such as polynorbornenes, [20][21][22][23][24] poly(arylene alkylene)s [25][26][27][28][29][30][31][32] and polystyrenes. [33][34][35][36][37][38] A more serious issue is the alkaline stability of the tethered cationic groups. These are generally ammonium cations that can degrade by a large number of different mechanisms, including nucleophilic substitutions at α-carbons, elimination of β-hydrogens (Hofmann elimination) and mechanisms unique to the specific structure and configuration of the cation.…”

Tripartite Cationic Interpenetrating Polymer Network Anion Exchange Membranes for Fuel Cells

“…The bending vibration of C−H on benzene appears at 706 cm −1 , and the two peaks at 1451 and 2925 cm −1 are ascribed to the inplane bending vibration and the symmetric stretching vibration of −CH 2 − on the PSVBC backbone, respectively. In addition, several new absorption peaks appear at 1021, 1650, and 3380 cm −1 on the spectra of NMPD-QPSVBC and TMHDA-QPSVBC, among which the absorption peak at 1021 cm −1 is attributed to the C−N bond, 29 demonstrating that the quaternized PSVBC has been successfully synthesized. This also corroborates with the results of 1 H NMR.…”