Molecular modeling of protonic acid doping of emeraldine base polyaniline for chemical sensors

We proposed a molecular modeling methodology to study the protonic acid doping of emeraldine base polyaniline which can be used in gas detection. The commerical forcefield COMPASS was used for the polymer and protonic acid molecules. The molecular model, which is capable of representing the polyaniline doping with the aqueous hydrochloric acid, was built by Monte Carlo method. The initial entire systems were equilibrated using a new protocol, which aims at creating a final structure with realistic density and low-potential energy characteristics. The doping process is modeled by a combined molecular mechanics and molecular dynamics simulation technique. The radial distribution functions of doped emeraldine salt and the relationships including pKa/pH and doping percentage/pH, were computed and compared with the experimental data. This method contributes a novel molecular modeling approach to select and evaluate the conducting polymers in chemical sensor applications.