Preparation and characterization of polypyrrole/nano-SrFe12O19 composites by in situ polymerization method

doi:10.1016/j.synthmet.2009.01.013

Synthetic Metals

Volume 159, Issue 11, June 2009, Pages 1008-1013

https://doi.org/10.1016/j.synthmet.2009.01.013 Get rights and content

Abstract

Polypyrrole (PPY)/nano-SrFe₁₂O₁₉ composites were synthesized by in situ polymerization method. The samples were characterized by TEM, SEM, XRD and IR technology. Spherical, conglobulation-like and arborization-like polypyrrole/SrFe₁₂O₁₉ composites were synthesized in an emulsion polymerization system for the first time. It was found that the morphology of PPY/nano-SrFe₁₂O₁₉ composites depended on the SrFe₁₂O₁₉ content of the reaction system. A possible mechanism for the formation of the different morphologic composites had been proposed. It was found that the saturation magnetization (M_S) and remanent magnetization (M_r) for the composites decreased with the decrease of the nano-SrFe₁₂O₁₉ content. The coercivity force (H_c) for the composites increased with the increase of PPY content when the PPY content was at a low value, and then decreased with the increase of PPY content. The possible mechanism for the phenomenon had been proposed. The conductivity was measured, and the variation mechanism of the composites conductivity was analyzed in the paper.

Introduction

Recently, conducting polymer composites with both electrical and ferromagnetic properties have received tremendous attention, and study on this kind of composites has becoming one of the most active and promising research area [1], [2], [3]. What makes conducting polymer composites so attractive is their potential applications in batteries [4], electro-chemical display devices [5], molecular electronics [6], electrical–magnetic shields, and microwave-absorbing materials [7], etc.

Polypyrrole (PPY) is one of the most promising conducting polymers due to unique properties, excellent environmental stability and potential application in electronic devices [8], [9]. Among the inorganic magnetic nano-particles, SrFe₁₂O₁₉ nano-particles had received great attention because of their excellent magnetic properties as well as extensive potential applications in the field of permanent magnetic material [10], [11], [12]. Recently, PPY composites containing ferrite nano-particles were mostly studied. Many methods had been reported for producing PPY/ferrite composites.

Xue et al. [13] obtained PANI–Fe₃O₄ nano-composites through mechanical mixing the DBSA–PANI powder and the HCl–PANI–Fe₃O₄ powder. Wan's group [14], [15], [16] prepared the PANI nano-composites containing Fe₃O₄ nano-particles by blending the PANI in N-methyl-2-pyrrolidone (NMP) with iron(II) sulfate aqueous solution, and precipitating Fe²⁺ into magnetite, and allowing the monomer to react with FeCl₂·4H₂O and FeCl₃·6H₂O, following by treatment with KOH aqueous solution. However, the most general method was by direct polymerization of aniline monomers in an aqueous solution in the presence of dispersed iron oxide particles with different surfactants. Deng et al. [17] reported the preparation of PANI/Fe₃O₄ nano-particles with core–shell structure via an in situ polymerization of aniline monomer in an aqueous solution, which contained Fe₃O₄ nano-particles and surfactant NaDS. He and Yu [18] and He [19], [20], [21] obtained sub-micrometer polyaniline/nano-silica, polyaniline/nano-ZnO and polyaniline/nano-CeO₂ composites by using nano-silica, nano-ZnO and nano-CeO₂ as the stabilizer for the Pickering emulsion, respectively. Yuan-Xun Li et al. [22] obtained tubular polyaniline–barium ferrite composite by in situ polymerization of aniline.

In this work, PPY/nano-SrFe₁₂O₁₉ composites were prepared in the phase of an emulsion polymerization system. The morphology of PPY/nano-SrFe₁₂O₁₉ composites could be modified by the amount of SrFe₁₂O₁₉. A possible formation mechanism of PPY/nano-SrFe₁₂O₁₉ composites was also discussed. The samples were characterized by various experimental techniques and magnetic properties and the conductivity of PPY/nano-SrFe₁₂O₁₉ composites were investigated.

Section snippets

Preparation of SrFe₁₂O₁₉ nano-particles

SrFe₁₂O₁₉ nano-particles were prepared by sol-gel method. The detailed process could be described as follows. Fe(NO₃)₃·9H₂O and Sr(NO₃)₂ (as the molar ratio of Sr/Fe equal to 1:12) were dissolved in 120 ml distilled water, then the entire mixture was stirred at 80 °C until Fe(NO₃)₃·9H₂O and Sr(NO₃)₂ were completely dissolved. Citric acid (as the molar ratio of acid/metal ion equal to 1:1) was added to the solution. The pH value of the solution was then adjusted to 6 with NH₃·H₂O. This solution

X-ray diffraction analysis

The XRD patterns of SrFe₁₂O₁₉ and PPY/SrFe₁₂O₁₉ composite nano-particles were shown in Fig. 1. As shown in Fig. 1, the XRD spectra showed diffraction peaks of SrFe₁₂O₁₉ (1 1 0), SrFe₁₂O₁₉ (1 0 7), SrFe₁₂O₁₉ (1 1 4), SrFe₁₂O₁₉ (2 0 3), SrFe₁₂O₁₉ (2 0 5) and SrFe₁₂O₁₉ (2 0 6) were all observed in each curve. The relative peak value of Fig. 1a was lower. That was because the relative PPY mass of sample C was higher than the other samples. But there was a wide peak observed in the ranges between 2θ = 20° and 30°

Conclusions

Polypyrrole/nano-SrFe₁₂O₁₉ composites were prepared by in situ polymerization method. It was found that the morphology of the resulting composites depended on the relative content of SrFe₁₂O₁₉ of the reaction system. The morphology of composites changed from sphere-like to conglobulation-like and arborization-like structure with increase of the pyrrole/SrFe₁₂O₁₉ mass ratio. A possible mechanism for the formation of the different morphologic composites had been proposed. In addition, it was

Acknowledgements

This work was supported by the National Nature Science Fund (20571066, 20871108), program for the Top Science and Technology Innovation Team of Higher Learning Institutions of Shanxi, and program for the Top Young Academic Leaders of Higher Learning Institutions of Shanxi.

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Preparation and characterization of polypyrrole/nano-SrFe12O19 composites by in situ polymerization method

Abstract

Introduction

Section snippets

Preparation of SrFe12O19 nano-particles

X-ray diffraction analysis

Conclusions

Acknowledgements

Electrochim. Acta

Synth. Met.

Electrochim. Acta

Synth. Met.

Synth. Met.

Microelectron. Eng.

J. Chromatogr. B

Synth. Met.

Synth. Met.

Mater. Lett.

Appl. Surf. Sci.

Powder Technol.

Preparation and characterization of polypyrrole/nano-SrFe₁₂O₁₉ composites by in situ polymerization method

Preparation of SrFe₁₂O₁₉ nano-particles