Polymerization of aniline under various concentrations of APS and HCl

Abstract

Effects from various initial molar ratios of aniline (AN), ammonium peroxydisulfate (APS) and HCl ([AN]:[APS]:[HCl]) on the polymerization of AN were investigated. First, a scheme derived from a molecular point of view was proposed to distinguish formation mechanisms based on their initial conditions. Thereafter, by choosing a relatively low ratio of [APS]/[AN]=0.23 at [AN]=0.27 M, three cases can be categorized according to this scheme: (A) [AN]≫[HCl], (B) [AN] slightly larger than [HCl] and (C) [AN]<[HCl]. For case (A), the initial solution has a richness of neutral ANs. Both the doped and the dedoped samples are confirmed to have features of phenazine-like oligomers. For case (C), neutral ANs are almost protonated to become anilinium cations. The final products possess features of polyaniline. For case (B), the samples possess both features from cases (A) and (C). Finally, the formation mechanisms for polymerization of AN were discussed.