Pulse Radiolysis and Polarography: Reactions of Oligomer and Polymer Radicals of Polyethylene Oxide at the Mercury Drop Electrode

Abstract

AbstractThe formation of polyethylene oxide (PEO) macroradicals of various chain lengths by the attack of OH radicals on dissolved PEO was initiated by a pulse of 12 MeV electrons and the polarographic currents of these macroradicals were recorded at various potentials. Measurements of the differential capacity of the double layer were also carried out to study the adsorption of polyethylene oxide at the mercury electrode. Macroradicals (chain length 45–230) were found to be more easily oxidized than oligomer radicals (chain length 2 and 4). The polarographic currents of the macroradicals were found to be produced solely by adsorbed macroradicals at potentials between ‐0.2 and ‐1.6 Volt vs. saturated calomel electrode, where polyethylene oxide is strongly adsorbed. These radicals were produced by OH attack on adsorbed macromolecules. Beyond that potential range, mobile macroradicals produced in solution can react at the electrode. The PEO coated electrode was also used to measure the polarograms of various free radicals produced by attack of hydrated electrons on various solutes. The electron adducts of uracil and fluorouracil exhibit a broad anodic wave indicating their strong reducing properties. The electron adduct of orotic acid was found to be a weaker reducing agent.