STRUCTURAL, THERMAL, AND ELECTRICAL CHARACTERIZATION OF LAYERED NANOCOMPOSITES DERIVED FROM NA-MONTMORILLONITE AND POLYETHERS

Nanocomposites are prepared from Na-montmorillonite and poly(ethylene oxide) or poly[oxymethylene oligo(oxyethylene)] and characterized by X-ray diffraction, impedance spectroscopy, DTA, and TGA. Two ordered phases with intersheet spacings of 13.6 and 17.7 angstrom, accommodating either single or double polymer layers within the montmorillonite galleries, are formed with polymer/Na-montmorillonite stoichiometries of 0.15 and 0.30 g/g, respectively. Materials prepared with intermediate stoichiometries yield diffraction profiles characteristic of solid solutions of these two phases. The details of composition and structure provide strong evidence that the polymer conformation is not helical as in crystalline PEO but more closely resembles an adsorbed layer. Sodium salts such as NaClO4 can also be incorporated into the polyether/clay phases. The double-layer phase exhibits a maximum stable ionic conductivity between 10(-5) and 10(-6) S cm-1 at 520 K.