The alkali stability of radiation-grafted anion-exchange membranes containing pendent 1-benzyl-2,3-dimethylimidazolium head-groups

Abstract

Radiation-grafted anion-exchange membranes (AEM) containing pendent benzyltrimethylammonium, 1-benzyl-3-methylimidazolium and 1-benzyl-2,3- dimethylimidazolium functional head-groups were synthesised with ion-exchange capacities in the range 1.7-1.9 meq g. The ionic conductivities of the AEMs were also comparable (24.5 ± 1.8 mS cm at 50°C). The alkali stability (in aqueous potassium hydroxide (1 mol dm ) at 60°C) of the 1-benzyl-2,3-dimethylimidazolium head-groups was superior to the 1-benzyl-3-methylimidazolium but inferior to the benzyltrimethylammonium benchmark head-groups. Radiation-grafted AEMs containing pendent 1-benzyl-2,3-dimethylimidazolium head-groups are not suitable for application in electrochemical devices containing highly alkaline environments. © 2013 The Royal Society of Chemistry

A review of radiation-grafted polymer electrolyte membranes for alkaline polymer electrolyte membrane fuel cells

“…X e represents the monovalent anions relevant to this study: Cl e , HCO 3 e , and OH e . Reproduced from [176] with permission. Copyright 2014 The Royal Society of Chemistry.…”

“…The anion conductivity reached 0.039 S cm À1 at 30 C in deionized water, and was found to increase with increasing temperature from 20 to 80 C. The membranes were tested for stability after being treated in 10 M aqueous KOH solution at 60 C for 120 h. The H 2 /O 2 fuel cell performance with these alkaline membranes at 40 C was 48 mW cm À2 at a current density of 69 mA cm À2 . Varcoe et al [176,177,188], Mamlouk et al [132,133,167], and Hasegawa et al [189] also used 60 Co as their gray source to pre-irradiate membranes when preparing radiationgrafted membranes for alkaline PEM fuel cell applications. Varcoe and Slade [110] employed an electron beam with a total dose of 7 MRad to irradiate ETFE membranes.…”

“…Imidazole-type alkaline membranes could also be prepared by the radiation grafting method. Page et al [176] grafted 1-(chloromethyl)-4-ethylbenzene onto a polymer matrix, followed by the addition of 1-methylimidazole to react with the modified membranes. The synthesis process is schematically shown in Fig.…”

High-pressure water electrolysis: Electrochemical mitigation of product gas crossover

“…By using AEMs, both advantages of high performance and low cost catalysts may be combined. Unfortunately, AEMs have not shown long-term durability by now [43][44][45][46][47].…”

Reduction of the monomer quantities required for the preparation of radiation-grafted alkaline anion-exchange membranes

“…Simultaneous radiation-grafting is where the precursor polymers are irradiated whilst submerged in the grafting monomer solution of choice and pre-irradiation-grafting is where the polymer precursors are initially irradiated (commonly in air) and then subsequently treated with the grafting monomer solution. The AAEMs produced at the University of Surrey are based on the electron-beam pre-irradiation-grafting of poly(ethylene-co-tetrafluoroethylene) (ETFE) with vinylbenzyl chloride (VBC) monomer (previously used in large quantities and undiluted) before subsequent quaternization with a tertiary amine of choice [12][13][14]. VBC is both expensive and hazardous when used in large quantities (potential mutagen, acutely toxic on skin adsorption and ingestion, and very toxic to aquatic life): it is therefore vital to significantly reduce the quantity required during the grafting step.…”