X-ray photoelectron spectroscopy and electrical conductivity of polyaniline doped with dodecylbenzenesulfonic acid as a function of the synthetic method

X-ray photoelectron spectroscopy (XPS) has been employed to investigate the protonation degree of polyaniline doped with dodecylbenzenesulfonic acid ( Pani. DBSA) obtained by different synthetic methods. The protonation degree has been compared to electrical conductivity. Pani.DBSA prepared through t he redoping process in an agate mortar displays conductivity values within the range of 1 S/cm. A protonation level of 48% with almost all imine group s being protonated. Pani.DBSA was also synthesized by oxidative polymerizat ion of aniline in the presence of DBSA, which acts simultaneously as a surf actant and as protonating agent. This in situ doping polymerization was car ried out in aqueous or toluene media. In both cases, protonation degrees hi gher than 50% have been achieved, indicating that a substantial portion of amine units have also been protonated. Higher doping degree has been achiev ed by aqueous dispersion polymerization of aniline. The C/N and S/N molar r atios obtained by XPS analysis indicate that the polyaniline chains obtaine d by in situ polymerization are protonated by both sulfonate and hydrogen s ulfate anions. (C) 2001 John Wiley & Sons, Inc.