Physicochemical interactions of deposited copper atoms with chemically synthesized polypyrrole films - An in-situ X-ray photoelectron spectroscopy study

An in-situ X-ray photoelectron spectroscopy (XPS) study of the physicochemical interactions between deposited copper atoms and chemically synthesized polypyrrole (PPY) films in its salt and partially undoped (deprotonated) forms was carried out. The XPS N(1s) spectra revealed that the incoming copper atoms reacted with the dopant anions in both types of films. This interaction brought about a simultaneous increase in the intrinsic oxidation state (measured by the [=N-]/[-NH-] ratio), of the polymer and is similar to undoping by deprotonation. The above postulation was: further supported by the corresponding changes in the Cu(2p(3/2)) and S(2p) spectra.. Due to the reaction between the copper atoms and the dopant anions of the polymer film, diffusion of copper atoms-into the bulk of the films was limited. The expected diffusion of oxygen from the conjugated polymer bulk, generally perceived as an oxygen reservoir, to the metal/ polymer interface was not observed in the present system. Hence, any interactions between the metal atoms and the polymer were unlikely to have involved oxygen.