Studies on Cu⁺² ion doped polyaniline

Abstract

Cu⁺² ion doped polyanilines (PANI) were synthesized by oxidative polymerization of aniline using ammonium persulphate in presence of copper sulphate solution having varying Cu⁺² ion concentration. Products were characterized by UV–Vis and FTIR spectroscopy. Morphology of the products was observed by SEM. Morphology of the emeraldine-base form of PANI (EB-PANI) changed when doped with Cu⁺² ion and its concentration had also shown influence on the morphology. Thermal stability of the Cu⁺² doped PANI was found to be less than that of EB-PANI. Experimental results showed that Cu⁺² ions were successfully incorporated into the polymer and there was a strong interaction between the Cu⁺² ions and PANI chains. Formation of semiquinone segments (polaron species) upon coordination with Cu⁺² ions was undoubtedly demonstrated by UV–Vis and FTIR spectroscopic results. FTIR spectroscopy showed shifts towards the lower wavenumbers for the Cu⁺² ion doped PANI as compared to EB-PANI. An increase in intensity of the band at 1,130 cm⁻¹ was observed which corresponds to the electronic like absorption confirming the doping of EB-PANI. Crystallinity was studied by powder XRD analysis and it was found that Cu⁺² ion doped PANI has developed a crystalline structure while EB-PANI is amorphous. Conductivity was found to be dependent on the concentration of the Cu⁺² ions and there was an optimum concentration of Cu⁺² ions for getting the highest conductivity.