Structure and conductivity in LB films of low-dimensional polymer electrolytes

LB films and bulk samples of complexes of (CF₃SO₂)₂NLi and LiClO₄ with polymers CH₂OCH_2- [(C₆H₃OR)CH₂O(CH₂OCH₂)(n-1)] where R=- C₁₆H₃₃ or -C₁₈H₃₇ and n=5 have been compared. Three-component systems incorporating equimolar proportions to the repeating unit of 'expander' C₁₆H₃₃OH or C₁₈H₃₈ are also discussed. The laminar structures of the complexes have been modelled by molecular dynamics. The LB multilayer films (400-600 Å) have been characterised using surface pressure-area isotherms, low angle X-ray scattering and impedance spectroscopy. Conductivity measurements both in the plane of the films and normal to the plane are reported and compared with measurements on bulk (100 μm) films. Temperature- independent conductivity is observed in the 'normal-to-plane' LB measurements. We propose that a morphological transformation occurs at the first heating during which the ion-mobile interlamellar planes become oriented normal to the electrodes.