Polyimides can undergo reversible electrochemical reduction/oxidation reactions. The electroactive centers have been identified as involving the aromatic‐carbonyl π‐system of the imide functional groups. The aromatic structure and substitution on the imide moiety affects the redox potentials. The reduced (radical‐anion and dianion) forms are stable and have strong absorbances in the visible spectral region. The degree of electronic transmission through the imide nitrogen for one‐ and two‐electron reductions has been investigated using a Hammett (σ) correlation. Delocalization of excess electron density in reduced imides has been studied using FTIR and UV‐Vis spectroscopy.

Interaction of polyimide and two simple organic polymers with an evaporated chromium metal overlayer was studied by surface-sensitive carbon 1s near-edge x-ray absorption fine structure (NEXAFS) spectroscopy. The technique was used to measure unoccupied electronic states in the polymers. Assignments of C1s→π* transitions in poly(pyromellitimido oxydianiline) (PMDA-ODA polyimide) were based upon transitions measured for model polymers which contained structural subunits of the polyimide. Changes in the NEXAFS spectrum of each polymer were observed after sequential depositions of chromium. Abrupt changes in the carbonyl C1s→π* transition peaks show that the carbonyl groups on these polymers are sites for initial interaction with chromium. No evidence was seen for the formation of Cr–arene complexes on any of the polymer surfaces.

No abstract

Abstract

No abstract