Kinetic Study of Polyaniline Film Formation Using Ferric Chloride/Ammonium Persulfate as Composite Oxidant

Abstract

Polyaniline (PANI) was synthesized by in situ emulsion polymerization. The kinetics of the PANI film formation was investigated by the quartz crystal microbalance technique (QCM). PANI film doped with dodecylbenzenesulfonic acid (DBSA) was synthesized by emulsion polymerization using ferric chloride/ammonium persulfate (FeCl3/APS) as composite oxidant in the presence of a constant (0.4 T) magnetic field (MF). The results showed that the peak current and conductivity of PANI synthesized by composite oxidant was higher than that synthesized by APS in the presence of an MF and it was also suggested that the PANI/FeCl3 composite has higher conductivity than pure PANI. The reaction exhibited first order with respect to composite oxidant, half-order to aniline, and half-order to DBSA, and the activation energy calculated from the temperature dependence of the growth rate was 40.23 kJ/mol. The polymerization conditions of aniline were optimized tentatively by cyclic voltammetry testing, which was studied by using carbon paper–loaded PANI as a working electrode for the first time. The experimental results indicated that the peak currents and conductivity of PANI were the largest under the following conditions: MF intensity of 0.4 T, composite oxidant concentration of 0.18 mol/L, and concentrations of aniline and DBSA of 0.08 mol/L and 0.05 mol/L, respectively.