Direct ESR detection and spin trapping of radicals generated by reaction of oxygen radicals with sulfonated poly(ether ether ketone) (SPEEK) membranes |
| |
Authors: | Mariana Pinteala Shulamith Schlick |
| |
Institution: | a Department of Chemistry and Biochemistry, University of Detroit Mercy, 4001 West McNichols, Detroit, MI 48221, USA b “Petru Poni” Institute of Macromolecular Chemistry, Aleea Grigore Ghica Voda 41A, 700487 Iasi, Romania |
| |
Abstract: | The stability of membranes under the strong oxidizing conditions in fuel cells is one of the major challenges in the development of fuel cells based on proton exchange membranes (PEMs). This study is centered on the determination of the susceptibility to degradation of SPEEK membranes exposed to OH radicals, using both direct ESR and spin trapping with 5,5-dimethyl-1-pyrroline-1-oxide (DMPO). In order to achieve a complete picture on SPEEK degradation, two types of experiments were performed: 1. UV irradiation at 77 K of SPEEK membranes swollen by aqueous solutions of H2O2; 2. UV irradiation of SPEEK membranes swollen by aqueous solutions of H2O2 in the presence of DMPO as a spin trap. UV irradiation without oxygen of SPEEK at 77 K in acid or basic form in the presence of H2O2/H2O produced phenoxyl radicals as the predominant radicals detected by direct ESR or spin trapping methods. At pH 4, the oxygen radicals produced phenyl radicals as the predominant species detected by spin trapping methods. The hydroperoxyl radical, as DMPO/OOH adduct, was detected only when the DMPO/OH adduct was absent. The appearance of phenyl and phenoxyl radicals provides the evidence that OH radicals react with the aromatic ring of SPEEK or leading to the scission of its ether bridge. |
| |
Keywords: | Sulfonated poly(ether ether ketone) (SPEEK) Electron spin resonance (ESR) 5 5-Dimethyl-1-pyrroline-1-oxide (DMPO) Spin trapping Free radicals |
本文献已被 ScienceDirect 等数据库收录! |
|