A mass spectrometric investigation of polyaniline using photoionization

Chemically and electrochemically generated polyaniline (PANI) was analysed mass spectrometrically using multiphoton ionization at wavelengths of λ = 262 nm and λ = 249 nm, respectively. The mass spectra obtained are characterized by a pattern of six fragmentation pathways which repeat themselves with every additional C6H4NH building block in the oligomer ions. The number of chinoid units in the polymer chain can be clearly identified. Spectra from PANI-coated stainless-steel probes reveal intensive iron signals upon ionization with λ = 249 nm radiation. It is argued that complexation of Fe to the aniline moiety is needed for iron evaporation. Such complexation appears to exist already in the surface film and might be related to the corrosion protection ability reported for PANI.