Optical reflectance and RBS studies of thermally aged CSA-protonated polyaniline films

Ageing of highly conductive CSA protonated PANI films has been investigated through reflectance spectrophotometry in the W-vis. near IR domain and Rutherford Backscattering Analysis. The reflectance spectra show distinct evolution stages: - increase of the metallic character after a time of some hours ageing at 135 degrees c following the loss of residual solvent - continuous degradation of the optical conductivity without variation of the dopant content over a period of 200 h and - accelerated oxidation and loss of dopant for higher aging times. We conclude to the existence of a physical aging stage leading to an improvement of the structural order at the mesoscopic scale, followed by a stage where dramatic alterations of the molecular structure are induced through chemical degradation.