Electrochemical and spectroelectrochemical characterization of some polypyrrole/anthraquinone sulfonate films

We have fabricated composite films of polypyrrole/quinone sulfonate via electropolymerization. The FTIR investigation indicated the incorporation of quinone sulfonate in the polypyrrole (PPy) film to compensate for a positive charge in the polymer chain. Further, the elemental analysis of PPy/9,10-anthraquinone-2-sulfonate (AQS(-)) showed that 0.29 of the sulfonate was incorporated per pyrrole unit. Cyclic voltammetric results in dimethylsulfoxide and dimethylformamide solutions showed that the two 1-electron transfer steps could be assigned to the formation of radical dianion (AQS(2-)) and trianion (AQS(3-)). The positive shift of the first cathodic peak for the incorporated AQS(-) indicated a strong interaction between the dianion acid the cationic sites of the polymer. The PPy/AQS(-) film worked as a cation-exchanger at electrode potentials below about -0.3 V vs. Ag/AgCl (saturated KCl) because of the creation of the anionic sites of the reduced quinone.