HYBRID NANOSTRUCTURES BASED ON CONDUCTING POLYMERS

R.Turcu1, A. Nan1, D. Bica2, L. Vekas2, N. Aldea1, D. Macovei3, R. Grecu4, O. Pana1, 
O. Marinica5, C.V.L. Pop1

1 National Institute R&D for Isotopic and Molecular Technologies, PO Box 700, 
Cluj-Napoca, Romania
2 Romanian Academy, Timisoara Branch, Magnetic Fluids Lab., Timisoara, Romania
3 National Institute R&D of Materials Physics, P.O.Box MG-7 Bucuresti-Magurele, Romania
4 Institute of Chemistry “Raluca Ripan” Cluj-Napoca Romania
5 National Center Eng. Syst. Complex Fluids Univ. Politehnica Timisoara, Romania

	Conducting polymers–magnetic particles nanocomposites have attracted increased interest due to their special physical properties making them suitable for different applications like: electromagnetic interference shielding, microwave absorbing, electronic devices, biotechnology.
	In this work we present the synthesis and characterization of hybrid structures obtained by the combination between polypyrrole (PPY) and magnetic nanoparticles like Fe3O4, CoFe2O4. In addition, a new hybrid nanostructure of carbon nanotubes (CNTs)-PPY containing magnetic nanoparticles Fe3O4 are reported. Our main goal is to gain insight into the effects of several synthesis parameters on the PPy magnetic nanocomposites properties in order to obtain the required characteristics for specific applications. 
	The magnetic nanocomposites PPY-Fe3O4 and PPY-CoFe2O4 were prepared by the oxidative polymerization of pyrrole in aqueous solution containing an oxidant and water based magnetic nanofluid. The polymerization of pyrrole in the presence of CNTs and Fe3O4 magnetic nanofluid results in the formation of the nanostructures of CNTs coated with PPY containing Fe3O4 nanoparticles.
	The properties of the composites were investigated by TEM, SEM, FTIR spectroscopy, d.c. conductivity, X-ray diffraction (XRD), X-ray Photoelectron spectroscopy (XPS) and magnetization measurements. The XPS investigations of PPY-Fe3O4 nanocomposites show that PPY chains contain a high fraction of positively charged nitrogen atoms due to the interaction with the anionic surfactant DBS and Fe3O4. The ddifferences between the FTIR spectra for PPY-Fe3O4 and PPY, appearing for the characteristic pyrrole ring vibrations, also suggest an interaction between PPY and magnetic nanoparticles. The magnetization of the PPY-Fe3O4 nanocomposites measured versus increasing and decreasing magnetic filed shows no hysteresis loop, this behavior being consistent with a superparamagnetic behavior. 	The properties of PPy magnetic nanocomposites are mainly determined by the magnetic fluid/pyrrole ratio and the polymerization time. The variation of these synthesis parameters allows the tailoring of electrical conductivity and magnetization values for PPy magnetic nanocomposites.