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 Rut herford Backscattering Analysis. The reflectance spectra show distinct evol ution stages: - increase of the metallic character after a time of some hou rs ageing at 135 degrees c following the loss of residual solvent - continu ous degradation of the optical conductivity without variation of the dopant content over a period of 200 h and - accelerated oxidation and loss of dop ant for higher aging times. We conclude to the existence of a physical agin g stage leading to an improvement of the structural order at the mesoscopic scale, followed by a stage where dramatic alterations of the molecular str ucture are induced through chemical degradation.