General Information
    • ISSN: 2010-0264
    • Frequency: Bimonthly (2010-2014); Monthly (Since 2015)
    • DOI: 10.18178/IJESD
    • Editor-in-Chief: Prof. Richard Haynes
    • Executive Editor: Ms. Nancy Y. Liu
    • Abstracting/ Indexing: Chemical Abstracts Services (CAS), CABI, Ulrich Periodicals Directory, Electronic Journals Library, Crossref, ProQuest.
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The University of Queensland, Australia
It is my honor to be the editor-in-chief of IJESD. The journal publishes good papers in the field of environmental science and development.
IJESD 2013 Vol.4(6): 633-636 ISSN: 2010-0264
DOI: 10.7763/IJESD.2013.V4.428

Self- Assembly of Saponite Nanoparticles Influenced by Interlayer H2O Molecules

K. Numata and K. Sato
Abstract—The rheological mechanism of long-term self-assembly caused by H2O molecules is highlighted for layered saponite nanoparticles based on the results of positronium (Ps) annihilation spectroscopy and thermogravimetry and differential thermal analysis (TG-DTA). A-type zeolite powder of typical cage material is also investigated to compare with the layered material. Prior to self-assembly, saponite nanoparticles exhibit two kinds of local molecular structures, where one and two nanosheets are inserted into interlayer spaces forming open spaces with their sizes of ~ 3 Å and ~ 9 Å, respectively. The angstrom-scale open spaces for the saponite vary in the time scale of ~ 100 h much longer than that of TG-DTA of ~ 8 h. The long-term molecular dynamics probed by Ps annihilation spectroscopy originates from the self-assembly of saponite nanoparticles. It is found that the self-assembly of layered saponite nanoparticles is accelerated with increasing the humidity from 35 % to 70 % owing to the formation of two-layer hydration. The present results demonstrate that the long-term self assembly originates from the layered structures together with H2O molecules on the layer surfaces.

Index Terms—Clay mineral, positronium, nanosheet, local molecular structure, open spaces.

The authors are with Department of Environmental Sciences, Tokyo Gakugei University, 4-1-1 Koganei, Tokyo 184-8501, Japan (e-mail:;


Cite:K. Numata and K. Sato, "Self- Assembly of Saponite Nanoparticles Influenced by Interlayer H2O Molecules," International Journal of Environmental Science and Development vol. 4, no. 6, pp. 633-636, 2013.

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