An optimised synthesis of high performance radiation-grafted anion-exchange membranes

Wang, Lianqin, Magliocca, E, Cunningham, E, Mustain, W, Poynton, S, Escudero-Cid, R, Nasef, M, Ponce-Gonzalez, J, Bance-Souahli, R, Slade, Robert et al, Whelligan, Daniel and Varcoe, John (2016) An optimised synthesis of high performance radiation-grafted anion-exchange membranes Green Chemistry, 19. pp. 831-843.

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Abstract

High performance benzyltrimethylammonium-type alkaline anion-exchange membranes (AEM), for application in electrochemical devices such as anion-exchange membrane fuel cells (AEMFC), were prepared by the radiation grafting (RG) of vinylbenzyl chloride (VBC) onto 25 μm thick poly(ethylene-co-tetrafluoroethylene) (ETFE) films followed by amination with trimethylamine. Reductions in electron-beam absorbed dose and amount of expensive, potentially hazardous VBC were achieved by using water as a diluent (reduced to 30 – 40 kGy absorbed dose and 5%vol VBC) instead of the prior-art method that used organic propan-2-ol diluent (required 70 kGy dose and 20%vol VBC monomer). Furthermore, the water from the aqueous grafting mixture was easily separated from residual monomer (after cooling) and was reused for a further grafting reaction: the resulting AEM exhibited an ion-exchange capacity of 2.1 mmol g-1 (cf. 2.1 mmol g-1 for the AEM made using fresh grafting mixture). The lower irradiation doses resulted in mechanically stronger RG-AEMs compared to the reference RG-AEM synthesised using the prior-art method. A further positive off-shoot of the optimisation process was the discovery that using water as a diluent resulted in an enhanced (i.e. more uniform) distribution of VBC grafts as proven by Raman microscopy and corroborated using EDX analysis: this led to enhancement in the Cl- anion-conductivities (up to 68 mS cm-1 at 80°C for the optimised fully hydrated RG-AEMs vs. 48 mS cm-1 for the prior-art RG-AEM reference). A down-selected RG-AEM of ion-exchange capacity = 2.0 mmol g-1, that was synthesised using the new greener protocol with 30 kGy electron-beam absorbed dose, led to an exceptional beginning-of-life H2/O2 AEMFC peak power density of 1.16 W cm−2 at 60°C in a benchmark test using industrial standard Pt-based electrocatalysts and unpressurised gas supplies: this was higher than the 0.91 W cm-1 obtained with the reference RG-AEM (IEC = 1.8 mmol g-1) synthesised using the prior-art protocol.

Item Type:	Article
Subjects :	Chemistry
Divisions :	Faculty of Engineering and Physical Sciences > Chemistry
Authors :	Name Email ORCID Wang, Lianqin lianqin.wang@surrey.ac.uk Magliocca, E Cunningham, E Mustain, W Poynton, S Escudero-Cid, R Nasef, M Ponce-Gonzalez, J Bance-Souahli, R Slade, Robert R.Slade@surrey.ac.uk Whelligan, Daniel D.Whelligan@surrey.ac.uk Varcoe, John J.Varcoe@surrey.ac.uk
Date :	23 November 2016
Funders :	EPSRC
DOI :	10.1039/C6GC02526A
Copyright Disclaimer :	CC - BY This article is licensed under a Creative Commons Attribution 3.0 Unported Licence.
Related URLs :	http://doi.org/10.15126/surreydata.00811...
Depositing User :	Symplectic Elements
Date Deposited :	28 Nov 2016 13:15
Last Modified :	16 Jan 2019 17:10
URI:	http://epubs.surrey.ac.uk/id/eprint/812946

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