Effect of Thermal Treatment on Electrical Conductivities of Polypyrrole Conducting Polymers

Some polypyrrole free standing films or membranes doped with different electrolytes (aromatic sulphonated) were prepared from aqueous monomer solutions in order to investigate the effect of thermal treatment on their electrical conductivity. It was found that the nature of counterion has the most important effect on determining the electrical conductivity and stability of conductivity when the polymer is exposed to high temperatures. However, mild heating can improve conductivity of polypyrrole conducting polymers. In order to carry out thermal effect studies on conductivity and measure the thermal stability of the PPy film, a variety of anions were examined. It was found that when polypyrrole is being doped with aromatic sulphonates (mainly benzene or naphthalene sulphonates) as counterions, it produces flexible and smooth films that can be readily detached from working electrode as membrane and they have good mechanical properties. Other counterions such as inorganics (e.g., Cl-, SO42-), aliphatic surfactants (e.g., DS), and polymerics (PVS) produce films that are either impossible to remove from working electrode, or give brittle, and rough films.