Preparation of a polymer-intercalated layered manganese oxide nanocomposite through a delamination/reassembling process
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Kenta Ooi National Institute of Advanced Industrial Science and Technology, Takamatsu, Kagawa 761-0395, Japan (Received 14 October 2005; accepted 16 March 2006)
Layered manganese oxide nanocomposite (PQN2MO) with Polyquaternium-2 (PQN2) incorporated between manganese oxide sheets was synthesized through a delamination/reassembling process. The synthesized material was characterized by powder x-ray diffraction (XRD), elemental analysis, thermal analysis, Fourier transform infrared spectroscopy, and scanning electron microscopy observation. XRD analysis showed that the expansion of the interlayer depended on the amount of PQN2 intercalated; the largest expansion was 0.94 nm, corresponding to a layer of PQN2 chains existing in the interlayer at an angle of about 30°. Chemical analysis results indicated that the tetramethylammonium (TMA+) ions in the interlayer were partly replaced by PQN2 polycations by an ion exchange mechanism, resulting in a nanocomposite in which TMA+ ions and PQN2 polycations simultaneously existed in the interlayer. The intercalated PQN2 polycations were selectively extracted, and TMA+ ions were stable enough to remain in the interlayer against the acid treatment. PQN2MO nanocomposite was composed of platelike nanocomposite particles. I. INTRODUCTION
In recent years, the synthesis of polymer/inorganic nanocomposites has received considerable attention because the synthesized materials have shown distinct characteristics different from those of the original materials.1–6 By the synergistic effects of nanostructure and the interaction of layered inorganic materials with organic polymers, many polymer/inorganic nanocomposites with electrical, optical, and mechanical properties have been obtained,7 which cannot be achieved with each component separately. So far, many synthesis methods have been developed and used to synthesize polymer/ inorganic nanocomposites, such as the in situ polymerization of intercalated monomers, the exfoliation of a layered host and subsequent adsorption of polymer and reaggregation, template syntheses of host structures in polymer-containing solutions, direct melt intercalation of a polymer into hosts, and others.8–10 An exfoliation technology of layered inorganic materials provides an efficient way of preparing nanocrystalline particles or colloidal solutions. The exfoliated nano-
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Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/JMR.2006.0202 1718 J. Mater. Res., Vol. 21, No. 7, Jul 2006 http://journals.cambridge.org Downloaded: 27 Mar 2015
layers behave like a new kind of inorganic macromolecule, which differ markedly from their bulk counterparts in physical and chemical properties such as quantum-size effects. Many inorganic layered solids, such as clay minerals, layered titanates, layered niobates, layered phosphates and superconductors, layered double hydroxides, and others, have been reported to be exfoliated in aqueous solutions.11–17 Because the delaminated nanosheets have a higher degree of freedom than the stacked sheets do,
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