Poly(o-methoxyaniline)-palladium systems:: effect of preparation conditions on physico-chemical properties

Physico-chemical properties of poly(o-methoxyaniline) (POMA) -palladium systems prepared in the PdCl2/HCl aqueous solutions depend on the HCl concentration in the solution. At low HCl concentration (0.66 x 10(-3) M) a two-phase system composed of the polymer phase and large crystalline metallic palladium particles (revealed by X-ray diffraction and scanning electron microscopic studies) is formed. At higher HCl concentrations (0.1 and 1 M) the presence of metallic Pd particles has not been detected. Based on spectroscopic investigations (IR, UV-Vis and XPS techniques) it has been established that formation of Pd metal proceeds on the account of partial oxidation of the POMA chain. Protonation of POMA with palladium chlorocomplexes as counterions and coordination of palladium(II) ions by the nitrogen and oxygen atoms of POMA are additional reactions taking place in the PdCl2 solution of low HCl concentration. These are the only reactions in the PdCl2 Solutions of higher HCl concentrations. In the work, POMA-palladium systems are compared with POMA protonated in the appropriate HCl solutions. (C) 2004 Elsevier B.V. All rights reserved.