The ozone-sensitive visible/near-IR absorbance changes of poly(2-chloroaniline) (P(2ClANI)), poly(N-methylaniline) (P(NMeANI)) and polyaniline (PANI) films were investigated. These three polymer films, which were assumed to be present partially in a protonated form and partially in a reduced form, were prepared by chemical oxidation of the monomers followed by treatment with the reducing agent disodium disulfite. The P(2ClANI) film was sensitive to ozone at concentrations of down to 2.5 ppm, but saturation of sensitivity started to appear above 50 ppm. By contrast, the PANI and P(NMeANI) films were sensitive to ozone in a concentration range of 50–100 ppm without showing saturation of sensitivity.
We report on the optical ozone sensitivity of a polyaniline (PANI) film prepared on the inner wall of a polystyrene cuvette by chemical oxidation of aniline from aqueous solution. The PANI film showed changes of optical absorbance in the presence of 50–100 ppm ozone in air at room temperature. The absorbance change was largest at wavelengths in the range of 500–800 nm. The absorbance changes brought about by ozone was partially reversible after removal of ozone from the atmosphere. These results suggest that PANI is a potential material for optical ozone detection.