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Updated: Jan 2, 2026

Using Cyclic Voltammetry, UV-Vis-NIR, and EPR Spectroelectrochemistry to Analyze Organic Compounds
Published on: October 18, 2018
Electron Spin Resonance Spectra of Polymer Radicals in Aqueous Solution
Roland E Florin1, Fred Sicilio1, Leo A Wall1
1Institute for Materials Research, National Bureau of Standards, Washington, D.C. 20234.
Abstract:
Mixing of aqueous polymer solutions containing Ti3+ and H2O2 in a rapid flow mixer produced radicals by abstraction, OH + RH → R · + H2O, which were observed by electron spin resonance. Oscillation of segments was sufficient to narrow the lines to 0.5-2.0 g. Polymers and radicals identified with more or less certainty were polyacrylic acid, 〰CH(CO2H)ĊHCH(CO2H)〰, polymethacrylic acid, 〰C(CH3)(CO2H)ĊHC(CH3)(CO2H)〰, polyvinyl alcohol, 〰CHOHĊHCHOH〰, and one indefinite, polyethylene imine, 〰CH2ṄCH2〰 or 〰CH2ṄOCH2〰, polyethylene oxide, 〰CH2OĊHCH2O〰. Radicals from polypropylene oxide, dextran, dextrin, soluble starch, and the disaccharide maltose were unidentified; the last three were strikingly similar. Products of secondary C-C scission were not observed with certainty. It is presumed that such reactions are slow compared to the time-scale of the experiment, 10 msec. However, some evidence exists for a very rapid β-OH loss in carbohydrate radicals and a slow C-O scission in polyethylene oxide radicals. A large number of related small molecule radicals were investigated, and hyperfine splittings and g-values are reported.
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