Electrochemical synthesis and characterization of polypyrrole-poly(Styrenesulfonate) composite coatings on carbon fibers

Polypyrrole-polystyrene sulfonate composite coatings have been formed on ca rbon fibers by an aqueous electrochemical process. The effects of process p arameters such as applied current density, monomer concentration, electroly te concentration, and the reaction time, on the electrochemical polymerizat ion of pyrrole onto carbon fibers were investigated. The rate of formation of the coatings increased with the current density and pyrrole concentratio n. It was, however, independent of electrolyte concentration, especially fo r polystyrene sulfonate concentration [PsSNa] of 0.05-0.25 M. At higher ele ctrolyte concentration [PsSNa] greater than or equal to 0.30 M, the rate of coatings formation increased with electrolyte concentration. The order of the rate of polymerization with respect to the electrolyte concentration wa s shown to be 0 and 1.0 at low and high electrolyte concentration, respecti vely. The polymerization potential, Ep, increased with the current density and decreased with pyrrole concentration. SEM micrographs showed that the m orphology of coatings varied with the electrolyte concentration. At low ele ctrolyte concentration, the coatings were rough and granular; however, at h igher electrolyte concentration the coatings were smooth and uniform. The d oping of polypyrrole films by polystyrene sulfonate ion was confirmed by in frared spectroscopy.