Infrared and Raman studies of palladium - nitrogen-containing polymers interactions

In the present research the nature of interactions of poly(4-vinylpyridine) (PVP) and polyaniline (PANI) with various Pd2+ chlorocomplexes existing in PdCl2-HCl-H2O solutions have been studied using IR (MLR, FIR) and Raman spectroscopies, It has been found that these interactions involve the nitrogen atoms of the polymers. In the PdCl2 solutions of high HCl concentration containing [PdCl4](2-) and [PdCl3(H2O)](-) as the major species acid-base type reaction (protonation) with the formation of the polymer salt as well as the coordination of Pd2+ ions by the nitrogen atoms of the polymer take place. In the PdCl2 solutions of low HCl concentration containing [PdCl2(H2O)(2)] as the major species protonation proceeds to a small extent. The main process in this case is most probably hydrolysis of the latter with the precipitation of hydrated palladium hydroxide or oxide on the polymer surface. In the case of PANI the oxidation-reduction between this precipitate and PANI takes place, It results in the oxidation of the polymer chain. (C) 1999 Elsevier Science B.V. All rights reserved.