Poly(3,4-ethylenedioxythiophene) Heterogeneity: A Differential Cyclic Voltabsorptometry Study

Abstract

A voltabsorptometry study of the redox behavior of poly(3,4-ethylenedioxythiophene) films in tetrabutylammonium tetrafluoroborate solutions in acetonitrile shows the polymer to exhibit heterogeneous properties when both reduced and oxidized. The measurements are taken at characteristic wavelengths λ selected on the basis of stationary absorption spectra. The reduced polymer's heterogeneity is explained under the assumption that the polymer contains simultaneously linear (λ = 530 nm) and spiral (λ = 660 nm) structures. The formation of two oxidized polymer states is proved experimentally. Both states presumably result from strong (λ = 880 nm) and weak (λ = 1050 nm) interactions between the anion and the positively charged polymer chain. The oxidized 880-nm state is shown to arise from the 660-nm state, whereas the 1050-nm state forms of the 530-nm state.