IONOMER-LIKE BEHAVIOR OF PROTONATED POLYANILINE - EFFECT OF IONIC-STRENGTH ON THE OPTICAL-SPECTRA

The absorbances of polyaniline (PAni) at 850 nm due to the electronic transition from a polaron band and at 130 cm-(1) due to vibrational ex citation of the hydrogen bond are observed to change non-linearly with the degree of protonation. The extent of non-linearity for these chan ges is dependent on the ionic strength of the protonating medium. The effect of ionic strength on the bands originating from the two differe nt types of transitions (electronic and vibrational) are found to be s imilar. A model has been proposed relating PAni with ionomers to accou nt for the observations. This also provides an explanation for the for mation of metallic islands in the polymer. It seems that the distribut ion of the dopants in the polymer matrix and the interchain interactio ns have a combined influence on the electronic structure of protonated PAni.