Polypyrrole Doped with Alkyl Benzene Sulphonates

The properties of polypyrrole (PPy) are to a large extent determined by the condition of synthesis and especially by the counterion incorporated as dopant during synthesis. In this work, PPy doped with different alkyl benzenesulfonates are compared. The polymer films are prepared by constant current oxidation of pyrrole in aqueous solutions containing sodium benzenesulfonates having alkyl chain lengths between 1 and 22 carbon atoms.

The doping levels of the polymers are evaluated both electrochemically and by means of a quartz crystal microbalance. The mechanical properties of freestanding films of the materials (tensile strength and Young's modulus) together with the reversible linear elongation between the oxidized and reduced states are determined.

A maximum in linear elongation of 4% is found for p-(n-octyl)benzenesulfonate, and the highest electronic conductivity is found for p-(n-butyl)benzenesulfonate.