J Supercond Nov Magn (2012) 25:1185–1193 DOI 10.1007/s10948-011-1396-x ORIGINAL PAPER Poly(vinyl phosphonic acid) (PVPA)–BaFe 12 O 19 Nanocomposite Z. Durmus · H. Kavas · H. Sozeri · M.S. Toprak · A. Aslan · A. Baykal Received: 22 September 2011 / Accepted: 13 December 2011 / Published online: 3 January 2012 © Springer Science+Business Media, LLC 2011 Abstract We present a method for the fabrication of PVPA/ BaFe 12 O 19 nanocomposite by in-situ polymerization of vinyl phosphonic acid, VPA in the presence of synthesized BaFe 12 O 19 NPs. Nanoparticles and the nanocomposite were analyzed by XRD, FTIR, TGA, SEM, TEM, VSM, and conductivity techniques for structural and physicochemi- cal characteristics. Nanoparticles, identified as BaFe 12 O 19 from XRD analysis, were successfully coated with PVPA and the linkage was assessed to be via P–O bonds. Electron microscopy analysis revealed aggregation of BaFe 12 O 19 particles and dominantly platelet morphology upon com- posite formation. TGA analysis revealed the composi- tion of the nanocomposite as 65% BaFe 12 O 19 and 35% polymer. Magnetic evaluation revealed that adsorption of PVPA anions during the preparation of the nanocompos- ite strongly influenced the magnetic properties resulting in much lower saturation magnetization values. DC conductiv- ity measurements were used to calculate activation energy of PVPA/BaFe 12 O 19 nanocomposite and it was obtained as 0.37 eV. Z. Durmus ( ) · A. Aslan · A. Baykal Department of Chemistry, Fatih University, 34500 Buyukcekmece, Istanbul, Turkey e-mail: zhrdurmus@gmail.com H. Kavas Department of Physics, Gebze Institute of Technology, 41400 Cayirova, Izmit, Turkey H. Sozeri TUBITAK-UME, National Metrology Institute, PO Box 54, 41470 Gebze-Kocaeli, Turkey M.S. Toprak Functional Materials Division, Royal Institute of Technology—KTH, SE16440 Stockholm, Sweden Keywords Magnetic nanomaterials · Nanocomposites · Conductivity · Dielectric properties 1 Introduction Materials consisting of nanometer-sized particles have at- tracted broad interest in fundamental sciences and tech- nological applications due to the novel and/or enhanced physicochemical properties different form micron-grained counterparts [1]. M-type barium hexaferrite with hexago- nal molecular structure BaFe 12 O 19 (Ba hexaferrite, BaM) is a promising material for permanent magnet, advanced recording, and microwave absorption because of its fairly large magnetocrystalline anisotropy, high Curie tempera- ture, relatively large magnetization, excellent chemical sta- bility, and corrosion resistivity, whereas its magnetic and electrical properties should be modulated to satisfy different applications [2–10]. Barium hexaferrite may be the most ex- tensively investigated material among the family of hard fer- rites having the general formula MeFe 12 O 19 , where Me = Ba, Sr, Pb [11]. There are many approaches to manufacture Ba-M-type ferrites, including the traditional ceramic sin- tering, coprecipitation, microwave plasma, reverse micelle method, etc. as well as in the foam form [12]. Poly(vinyl phosphonic acid) (PVPA) is a simple poly- meric acid which can be produced by free-radical polymer- ization of vinyl phosphonic acid, VPA [13]. Recently, it gained increasing interest as a model system to study the proton conduction mechanism of phosphonated polymers suggested for applications in fuel cells [14]. Other applica- tions are concerned with the protection of metal surfaces as a primer [15–18] or as a reactive component in dental cements [19–21].