Poly(ethylene oxide)/NH4+-smectite nanocomposites

New materials based on the intercalation of poly(ethylene oxide), PEG, into homoionic NH4+-smectites (montmorillonite and hectorite) have been synthesised and characterised. IR spectroscopy of the resultant nanocomposites shows changes in the polymer helical conformation of PEO as well as in the T-d symmetry of the ammonium ion. Intercalation of PEO into NH4+-hectorite produces a material with regular stacking of the clay layers, but in PEO/NH4+- montmorillonite, the layers appear to be irregularly stacked with PEO chains arranged in double layers. However, by exchanging MH4+ with Na+ ions, the layer stacking becomes ordered. Ionic conductivity of these materials is lower than that of analogous materials containing all;ali metal cations. Typical conductivity values measured in a direction parallel to the silicate layers at 200 degrees C are in the order of 10(-7) S/cm. (C) 1999 Elsevier Science B.V. All rights reserved.