Chemical degradation of aged CSA-protonated PANI films analyzed by XPS

Highly conductive CSA-protonated PANI films cast from m-cresol solutions of high Mw PANI were aged at 135 °C in air up to 20 days. Pristine and aged films were characterized by: conductivity measurements, elemental analysis, XPS and FTIR. The conductivity decay is correlated to a progressive degradation involving: (i) dedoping, (ii) CSA desulfonation, fragmentation and sulfonation of PANI backbone, (iii) oxidation (O incorporation), and (iv) chemical crosslinking by formation of interchain tertiary amine bonds.