Ferromagnetic polyaniline (PANI)/TiO2 nanocomposites were synthesized
by the oxidative polymerization of aniline with ammonium peroxydisulfate
(APS), in the presence of colloidal TiO2 nanoparticles and TiO2 nanotubes,
without added acid. The morphological, magnetic and structural properties
of the PANI/TiO2 nanocomposites were studied by SEM microscopy,
SQUID magnetometer and FTIR spectroscopy. The electrical conductivity
of synthesized nanocomposites was ~10-3 Scm-1. The room temperature
ferromagnetic response significantly depends on shape of TiO2
nanoparticles

Konstantinović, Zorica

Radoičić, Marija B.

Ćirić-Marjanović, Gordana N.

Šaponjić, Zoran

Repository of the Vinča Nuclear Institute (VinaR)

     PHYSICAL CHEMISTRY 2014  12th International Conference on Fundamental and Applied Aspects of Physical Chemistry          The Conference is dedicated to the 25. Anniversary of the Society of Physical Chemists of Serbia            September 22-26, 2014  Belgrade, Serbia   II   ISBN 978-86-82475-30-9 Title: PHYSICAL CHEMISTRY 2014 (Proceedings) Editors: Ž. Čupić and S. Anić Published by: Society of Physical Chemists of Serbia, Studenski trg 12-16, 11158, Belgrade, Serbia Publisher: Society of Physical Chemists of Serbia For Publisher: S. Anić, President of Society of Physical Chemists of Serbia Printed by: “Jovan” Priting and Publishing Company; 200 Copies; Number of pages: 6+ 441; Format: B5; Printing finished in September 2014.  Text an Layout: “Jovan”  Neither this book nor any part may be reproduced or transmitted in any form or by any means, including photocopying, or by any information storage and retrieval system, without permission in writing from the publisher.  200 - Coppy priting    IV  PHYSICAL CHEMISTRY 2014  12th International Conference on  Fundamental and Applied Aspects of Physical Chemistry     Organized by The Society of Physical Chemists of Serbia  in co-operation with   Institute of Catalysis Bulgarian Academy of Sciences   Boreskov Institute of Catalysis of Siberian Branch of the Russian Academy of Sciences  Faculty of Physical Chemistry, University of Belgrade, Serbia  Institute of Chemistry Technology and Metallurgy,  University of Belgrade, Serbia  Vinča Institute, University of Belgrade, Serbia  Institute of General and Physical Chemistry, Serbia    Faculty of Pharmacy, University of Belgrade, Serbia    VInternational Organizing Committee  Chairman:  S. Anić (Serbia) Vice-chairman:  M. Gabrovska (Bulgaria)                             V. A. Sadykov  (Russia)  Members: N. Cvjetičanin (Serbia), S. N. Blagojević (Serbia), M. Daković (Serbia), T. Grozdić (Serbia), D. Jovanović (Serbia), M. Kuzmanović (Serbia), D. Marković (Serbia), J. Marković-Dimitrić (Serbia), B. Milosavljević (USA), M. Mojović (Serbia), N. Ostrovski (Serbia), I. Pašti (Serbia), M. Petković (Serbia), A. Popović-Bjelić (Serbia),  B. Simonović (Serbia), D. Stanisavljev (Serbia),  B. Šljukić (Serbia), N. Vukelić (Serbia), V. Vukojević (Sweden)  International Scientific Committee  Chairman:  Ž. Čupić (Serbia) Vice-chairmans: V. N. Parmon (Russia)                                   S. Rakovsky (Bulgaria) Members: B. Adnađević (Serbia), S. Anić (Serbia), A. Antić-Jovanović (Serbia), G. Bačić (Serbia), A. Kelarakis (Greece), R. Cervellati (Italy), V. Dondur (Serbia), Ivan Gutman (Serbia), S. D. Furrow (USA), K. Hedrih (Serbia), M. Jeremić (Serbia), A. V. Knyazev (Russia), Lj. Kolar-Anić (Serbia), V. Kuntić (Serbia), Z. Marković (Serbia),  S. Mentus (Serbia), Š. Miljanić (Serbia), M. Perić (Serbia), M. Plavšić (Serbia), D. M. F. Santos (Portugal), G. Schmitz (Belgium), I. Schreiber (Czech), P. Sevčik (Slovakia), B. C. Simionescu (Romania), N. Stepanov (Russia), D. Todorović (Serbia), M. Trtica (Serbia), V. Vasić (Serbia), D. Veselinović (Serbia)   Local Executive Committee  Chairman:              S. Blagojević Vice-chairmans:    A. Ivanović-Šašić  Members: P. Banković,  N. Bošnjaković, J. Dostanić,  A. Đerić, A. Ignjatović, A. Jović, N. Jović-Jovičić, D. Lončarević, J. Krstić, J. Maksimović, V. Marković, M. Milenković, S. Maćešić, V. Marković, B. Nedić, N. Potkonjak, D. Ranković, M. Stević, M. Žunić, M. Ristić,          PHYSICAL CHEMISTRY 2014  H-13-P   643FERROMAGNETIC RESPONSE OF NANOCOMPOSITES BASED ON POLYANILINE AND TiO2 NANOCRYSTALS OF DIFFERENT SHAPE  M. Radoičić 1, Z.Šaponjić 1, Z. Konstantinović 2 and G. Ćirić-Marjanović 3   1Vinča Institute of Nuclear Sciences, University of Belgrade,  Belgrade 11001, Serbia 2Institut de Ciencia de Materials de Barcelona, CSIC, Bellaterra, 08193 Barcelona, Spain 3Faculty of Physical Chemistry, University of Belgrade, Belgrade 11158, Serbia    ABSTRACT Ferromagnetic polyaniline (PANI)/TiO2 nanocomposites were synthesized by the oxidative polymerization of aniline with ammonium peroxydisulfate (APS), in the presence of colloidal TiO2 nanoparticles and TiO2 nanotubes, without added acid. The morphological, magnetic and structural properties of the PANI/TiO2 nanocomposites were studied by SEM microscopy, SQUID magnetometer and FTIR spectroscopy. The electrical conductivity of synthesized nanocomposites was ~10-3 Scm-1. The room temperature ferromagnetic response significantly depends on shape of TiO2 nanoparticles.  INTRODUCTION Polyaniline (PANI) is one of the most important conducting polymers, due to its simple synthesis, unique doping/dedoping chemistry, low cost, high conductivity, and excellent environmental stability [1]. The crystallinity, solubility, thermal stability, electrical, magnetic and optical properties of PANI mainly depend on its oxidation state and protonation degree [2]. Depending on synthetic and isolation procedure, polyaniline contains various proportions of diamagnetic [(–B–NH+–Q– NH+–)n(–B–NH–)2n](A−)2n and paramagnetic units [(–B–NH•+–B–NH–)n](A−)n, where B, Q and A−denote a benzenoid ring, quinonoid ring and dopant anion, respectively. Magnetic properties of PANI and its derivatives have been extensively studied because they can provide important data on charge-carrying species and unpaired spins. It has been found that the magnetic susceptibility of doped PANI is strongly influenced by the manner of polymer preparation (e.g., doping level, dopant type), and measuring conditions (temperature, applied magnetic field) [3]. Although a numerous        PHYSICAL CHEMISTRY 2014  H-13-P   644studies on magnetic properties of PANI are published just a few of them reported on ferromagnetic behavior [4]. In this work, conducting PANI/TiO2 nanocomposites have been prepared by the chemical oxidative polymerization of aniline in aqueous dispersions of TiO2 nanoparticles and nanotubes, without added acid.  Synthesized PANI/TiO2 nanocomposites were studied by SEM analysis, FTIR spectroscopy and electrical conductivity measurements. In order to investigate the influence of the shape of TiO2 nanoparticles on ferromagnetic response of PANI, magnetic susceptibility measurements were performed at room temperature.  EXPERIMENTAL The colloidal dispersion of TiO2 nanoparticles (d4.5 nm) of was prepared by acid hydrolysis of TiCl4 [5]. Titania nanotubes (outer and inner diameters 10 and 7 nm and length of few 100 nm) were synthesized by a hydrothermal process in alkaline medium [6]. PANI/TiO2 nanocomposites were prepared by following procedures: the aqueous solution of APS (0.4 M, 25 ml) was poured into the aqueous solution of aniline (0.32 M, 25 ml). Thereupon dispersion of TiO2 colloidal nanoparticles/nanotubes in water (50 ml) was added into the aniline/APS solutions. The reaction mixture was stirred for 3 h at room temperature. The precipitated PANI/TiO2 nanocomposite was collected on a filter, rinsed with ethanol acidified with sulfuric acid (5 × 10-3 M), and dried in vacuum at 60 oC for 3 h. The mole ratios of aniline to TiO2 nanoparticles and nanotubes were 80, (PT-80 and PT-NT-80). As a reference, the pure PANI sample was prepared by the same procedure.  RESULTS AND DISCUSSION The changes in the morphology of the synthesized nanocomposites by varying a shape of TiO2 nanoparticles are studied by SEM microscopy (Figure 1). The morphology of the nanocomposite samples (PT-80 and PT-NT-80) is significantly different compared to the morphology of pure PANI sample. Nanoribbons, as well as nanorods/tubes predominate in the non-uniform morphology of pure PANI sample. Incorporation of colloidal TiO2 nanoparticles, as well as TiO2 nanotubes caused predomination of nanotubular morphology in PANI/TiO2 nanocomposite samples, while nanoribbons are not observed (Figure 1). PANI nanotubes have an outer diameter of 60–150 nm and a length up to few micrometers.         PHYSICAL CHEMISTRY 2014  H-13-P   645Figure 2. The magnetic field dependence of magnetization after diamagnetic correction at 300 K for the pure PANI and PANI/TiO2 nanocomposite samples (PT-80 and PT-NT-80).  Figure 1. SEM images of the pure PANI (A) and PANI-TiO2 nanocomposites PT-80 (B) and PT-NT-80 (C).  In the FTIR spectrum of PANI/TiO2 nanocomposite, characteristic bands of PANI were observed at wavenumbers 1569, 1497, 1305, 1246, 1146 and 825 cm–1 indicating the presence of emeraldine salt form of PANI chains in PANI and PANI/TiO2 nanocomposites. Weak bands at 1635 and 1400 cm-1 observed in the FTIR spectra of pure PANI and all nanocomposites can be attributed to the substituted phenazine-like units which are responsible for formation of polyaniline nanostructures.  The conductivity of both PANI-TiO2 nanocomposites was ~2.010–3 S cm–1, which is twice the conductivity of a pure PANI (9.1  10–4 S cm–1) synthesized under the same conditions, without added TiO2.  The field dependence magnetization after diamagnetic correction is shown in Figure 2. At room temperature, the weak ferromagnetic behavior can be observed in all samples. Pure PANI and PT-80 samples showed hysteresis loop with the coercive field of Hc=300 Oe, remanent magnetization of Mr= 4.35×10-4 emu g-1 and the saturation magnetization of        PHYSICAL CHEMISTRY 2014  H-13-P   646about Ms=2×10-3 emu g-1. In comparison to pure PANI and PT-80 samples, PT-NT-80 nanocomposite sample exhibit much weaker ferromagnetic ordering. Saturation magnetization was approximately Ms=2.5×10-4 emu g-1. The presence of TiO2 nanotubes in PANI-based nanocomposite reduced several times the saturation magnetization value. Such behavior could be the consequence of the increased spin disordering as well as the reduction of the total number of magnetic moments. The reason for decrease of ferromagnetism in PT-NT-80 nanocomposite sample is conversion of single-charged polarons into double-charged bipolarons (S=0) induced by the presence of TiO2 nanotubes.  CONCLUSION PANI/TiO2 nanocomposites were successfully synthesized through the oxidative polymerization of aniline with ammonium peroxydisulfate in aqueous dispersions of TiO2 nanoparticles and TiO2 nanotubes, without added acid. FTIR measurements confirmed presence of conductive emeraldine salt form of PANI in all synthesized samples. Incorporation of TiO2 nanoparticles and nanotubes caused significant changes in morphology and conductivity of nanocomposites compared to pure PANI. Much weaker ferromagnetic ordering in PANI/TiO2 nanocomposites which contains TiO2 nanotubes is due to the presence of higher amount of double-charged bipolarons (S=0).   ACKNOWLEDGEMENT  This work was supported by the Ministry of Education, Science and Technological Development of the Republic of Serbia (Grants no. 172056 and 45020).  REFERENCES [1] K. Lee, S. Cho, S.H. Park, A.J. Heeger, C.-W. Lee, S.-H. Lee, Nature, 2006, 44, 65. [2] J. Stejskal, P. Kratochvíl, A.D. Jenkins, Polymer, 1996, 37, 367 [3] Y. Long, Z. Chen, J. Shen, Z. Zhang, L. Zhang, H. Xiao, M. Wan, and J.L. Duvail, J. Phys. Chem. B, 2006, 110, 23228. [4] Y. Zhang, C. Zhu, and J. Kan, J. Appl. Polym. Sci., 2008, 109, 3024. [5] T. Rajh, D. Tiede, M. Thurnauer, J. Non-Cryst. Solids, 1996,  207, 815. [6] Z.Šaponjić, N. Dimitrijević, D. Tiede, A. Goshe, X. Zuo, L.X. Chen, A.S. Barnard, P. Zapol, L. Curtiss L, T. Rajh, Adv. Mater., 2005, 17, 965.  

Ferromagnetic response of nanocomposites based on polyaniline and TiO2 nanocrystals of different shape

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Ferromagnetic response of nanocomposites based on polyaniline and TiO2 nanocrystals of different shape

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