Influence of polymerization condition on the electrical conductivity and gas sensing properties of polyaniline

Polyaniline (PANI) salt was synthesized by oxidative polymerization of aniline hydrochloride in hydrochloric acid (HCl) medium of different concentrations. The plots of temperature of the polymerization medium with time and polymer yield with time gave valuable insight into the polymer growth and structural change of PANI with varied strength of the protonating medium. The PANI salt obtained after polymerization reaction and the PANI films obtained after post reaction doping by exposing to same strength of HCl medium showed marked resemblance of structure characterized by UV and elemental (Cl/N ratio) analyses. This provided us an opportunity to optimize the HCl concentration of the polymerization reaction medium to get PANI with better electrical conductivity and ammonia gas sensing characteristics.