Polymer Compatibility, Phase Separation and High Ambient Conductivity in Low - Dimensional Polymer Electrolyte Blends with Lithium Salts

AC and DC conductivities of complexes of Li salts with the amphiphilic helical polyether poly[2,5,8,11,14-pentaoxapentadecamethylene(5-hexadecyloxy-1,3-phenylene)] (I) (Type A complexes) and blends of I with copolymers of poly(tetramethylene oxide) oligomer coupled with either - (CH(2) -)- (polymer IIC1) or -(CH(2))(12) - (IIC12) (Type C complexes) are reported. Whereas Type A complexes give reversible AC impedance plots log sigma vs. 1/ T plots which are ca. 10(-7) S cm(-1) at ambient, the Type C blends rise to ca. 10(-3) S cm(-1) at 100 degrees C and on cooling to ambient maintain this high level. In Type C systems with IIC12 this transformation is stable and permanent. Optical microscopy reveals phase separation of extensive well-organised lamellae of the Type A phase from the Type C blend following heating. Polymer U resides in thin layers in the interlamellar spaces serving to transfer ions between them. DC data at ambient temperatures for Li I I : II : Li salt I Li cells indicate conductivities 10(-3) to 10(-2) S cm(-1) over extended periods (24 hours).