Physicochemical properties of electrochemically prepared polypyrrole perchlorate

Polypyrrole perchlorate (PPy-ClO4) has been prepared by electrochemical polymerization in an acetonitrile solution. We present the results of extensive measurements on the physicochemical properties of the PPy-ClO4 films by electrical, magnetic, electrochemical, and thermal analysis. Cyclic voltammetry demonstrates that both of the peak current and potential strongly depend on the scan rate, implying the electrode reaction process of PPy-ClO4 is irreversible. Thermal analyses by thermogravimetric analysis (TGA) and by differential thermal analysis (DTA) show that a weight loss occurs between 250–320°C with a glass transition temperature Tg≈268°C, which is much higher than the previous works. The temperature dependence of the electrical conductivity, σ(T), is presented and analyzed using several models. The results demonstrate that the transport properties of PPy-ClO4 can be described well by ln[σ(T)T1/2] vs. T−1/4 plot, corresponding to the phonon-assisted hopping process for the charge carriers. We discuss the implication of the data in relation with the microscopic and morphological structure of the samples.