title: Reactive oxygen species accelerate degradation of anion exchange membranes based on polyphenylene oxide in alkaline environments.
abstract: Anion exchange membranes (AEM) based on polyphenylene oxide (PPO) suffered quaternary-ammonium-cation-site degradation in alkaline environments. Surprisingly, the degradation rate was considerably faster in the presence of molecular oxygen. We postulated that the AEM cation-site catalyzes the reduction of dioxygen by hydroxide ions to yield the superoxide anion radical and the highly reactive hydroxyl free radical. We substantiated our hypothesis by using a phosphorous-containing spin trap (5-diisopropoxy-phosphoryl-5-methyl-1-pyrroline-N-oxide) to detect the adducts for both free radicals in situ using (31)P-NMR spectroscopy.
authors.affiliation: Center for Electrochemical Science and Engineering, Department of Chemical and Biological Engineering, Illinois Institute of Technology, 10 W. 33rd St., Chicago, IL 60616, USA. ramani@iit.edu.
authors.forename: Javier
authors.initials: J
authors.lastname: Parrondo
authors.affiliation: Center for Electrochemical Science and Engineering, Department of Chemical and Biological Engineering, Illinois Institute of Technology, 10 W. 33rd St., Chicago, IL 60616, USA. ramani@iit.edu.
authors.forename: Zhongyang
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Center for Electrochemical Science and Engineering, Department of Chemical and Biological Engineering, Illinois Institute of Technology, 10 W. 33rd St., Chicago, IL 60616, USA. ramani@iit.edu.
authors.forename: Min-Suk J
authors.initials: MS
authors.lastname: Jung
authors.affiliation: Center for Electrochemical Science and Engineering, Department of Chemical and Biological Engineering, Illinois Institute of Technology, 10 W. 33rd St., Chicago, IL 60616, USA. ramani@iit.edu.
authors.forename: Vijay
authors.initials: V
authors.lastname: Ramani