Electrochemical and spectroelectrochemical properties of nitroxyl radical species in PTMA, an organic radical polymer. Influence of the microstructure

In this work, an electrochemical and ESR-spectrochemical study of the oxidation properties for nitroxide radicals contained in the structure of poly(4-methacryloyloxy-2,2,6,6-tetramethylpiperidin-N-oxyl) (PTMA) in acetonitrile solution was performed. Results revealed that this polymer contains two types of nitroxide radical species, the first associated to a multielectronic and reversible electron transfer process. Remaining radical species are irreversibly oxidized at more positive potential values. Proportions obtained for the respective amount of each oxidized species, 78% and 22% respectively, are similar to the values expected due to the difference in syndiotactic:heterotactic triads in the polymer and reported values for the experimental charge/discharge efficiencies of batteries constructed with this material. These effects also influence electron transfer kinetics during the oxidation of each type of radical species in the polymer. These findings suggest that the detailed understanding of the oxidation processes of different microstructures in radical polymers is useful to analyze performance based in these materials.