Issue 75, 2017, Issue in Progress

A Raman spectro-microscopic investigation of ETFE-based radiation-grafted anion-exchange membranes

Abstract

This study used Raman spectro-microscopy to investigate the synthesis and degradation of radiation-grafted anion-exchange membranes (RG-AEM) made using 50 μm thick poly(ethylene-co-tetrafluoroethylene) (ETFE) films, vinylbenzyl chloride (VBC) monomer, and 1-methylpyrrolidine (MPY) amination agent. The data obtained confirmed the operation of the grafting-front mechanism. VBC grafting times of 1 and 4 h led to low degrees of grafting homogeneity, while 72 h led to extreme levels of grafting that resulted in mechanically weak RG-AEMs due to the excessive H2O contents. A grafting time of 16 h was optimal yielding a RG-AEM with an ion-exchange capacity (IEC) of 2.06 ± 0.02 mmol g−1 (n = 3). An excess of grafting was detected at the surface of this RG-AEM (at least within the first few μm of the surface). This RG-AEM was then degraded in O2-purged aqueous KOH (1.0 mol dm−3) for 14 d at 80 °C. Degradation was detected throughout the RG-AEM cross-section, where the Raman data was quantitatively consistent with the loss of IEC. A slight excess of degradation was detected at the surface of the RG-AEM. Degradation involved the loss of whole benzyl-1-methypyrrolidinium grafted units as well as the direct attack on the pendent (cationic) pyrrolidinium groups by the hydroxide anions.

Graphical abstract: A Raman spectro-microscopic investigation of ETFE-based radiation-grafted anion-exchange membranes

Supplementary files

Article information

Article type
Paper
Submitted
30 Aug 2017
Accepted
03 Oct 2017
First published
11 Oct 2017
This article is Open Access
Creative Commons BY license

RSC Adv., 2017,7, 47726-47737

A Raman spectro-microscopic investigation of ETFE-based radiation-grafted anion-exchange membranes

W. H. Lee, C. Crean, J. R. Varcoe and R. Bance-Soualhi, RSC Adv., 2017, 7, 47726 DOI: 10.1039/C7RA09650J

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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