SOLUBLE CONDUCTING POLYPYRROLE DOPED WITH DBSA-CSA MIXED ACID

Soluble conductive polypyrrole (PPy) with room temperature conductivit y (2-18 S/cm) has been synthesized by doping polypyrrole with mixed ac id containing camphor sulfonic acid (CSA) and dodecyl benzene sulfonic acid (DBSA). The solubility and the room temperature conductivity of PPy doped with mixed acid were measured as a function of component of CSA-DBSA mixed acid, and the structure of PPy was characterized by Fou rier transform infrared (FTIR), ultraviolet-visible (UV-vis) spectra, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy ( SEM) and thermogravimetric analysis (TGA). PPy doped with DBSA-CSA mix ed acid is soluble in m-cresol although PPy doped only by CSA is compl etely insoluble in any solvent. The solubility of PPy doped with mixed acid increases with an increase in the fraction of DBSA in the mixed acid, while the room temperature conductivity of the PPy increases wit h increasing CSA molar fraction. The UV-vis spectra and electron spin resonance (ESR) measurements showed that both polaron and bipolaron ar e the charge carrier in the doped PPy with mixed acid. It was proposed that the contribution of CSA to the solubility of PPy doped with mixe d acid is to decrease the interaction among PPy chains due to the larg e molecular size of CSA, while DBSA contributes to the solubility by i ts good solvating effect derived from its long alkyl chain. These may be a reason that both the solubility and conductivity of PPy are impro ved by the presence of CSA compared with those of PPy doped only with DBSA. (C) 1998 John Wiley & Sons, Inc.