Ionic Conductivity of Lithium Salt/Oligo(ethylene oxide)-Based Liquid-Crystal Mixtures: The Effect of Molecular Architecture on the Conduction Process

摘要

This paper presents new block copolymers containing PEO segments for use as polymer electrolytes and the possibility to tune the ionic-conduction properties from the solvent molecular architecture. These new mesogenic materials present hydrophobic (apolar, i.e., aromatic and aliphatic) and hydrophilic (polar, i.e., ethylene oxide) segments on the same molecular core, allowing clustering of Li~+ cations and control over their segmental reorientation. The reduced ordering and the high mobility of the nematic phase compared with the crystalline state allows study of these materials using aniso-tropic NMR techniques. The ionic conductivity of these electrolytes is good, even for materials with longer PEO chains that have the tendency to crown Li~+ ions. Further studies are currently in progress on various families of mesogenic materials (smectic, columnar, etc.) for which anisotropic ionic conductivity is expected. Theoretical calculations and anisotropic NMR methods will also be developed to investigate the conduction process from the local scale molecular motion modes