Effect of NH3 gas on the electrical conductivity of polyaniline blend films

The effect of NH3 gas on the electrical conductivity of four kinds of polyaniline-insulating matrix polymer blend films was investigated for the purpose of preparing a practical NH3 gas sensor operable near or at room temperature. The electrical conductivity of all blend films measured in N2 was enhanced above a 2 wt.% of composition of polyaniline. The electrical conductivity decreased by exposure of the blend films to NH3 gas. It was found that the sensing characteristics depended on the kind of dopant species, measuring temperature, matrix polymers, and the solvent used for film preparation. Among the considered sensors, the polyaniline–poly(methyl methacrylate) blend film prepared with toluene as the solvent showed the fastest response and good reversibility, because the porous film was obtained only by this combination.