Effect of phase separation on ionic conductivity of poly(methyl methacrylate)-based solid polymer electrolyte

Transparent and highly conductive solid polymeric electrolytes (SPE) based on poly(ethylene glycol) methyl ether (PEGMe), blended with poly(methyl methacrylate) (PMMA) and doped with lithium perchlorate were prepared for application in all-solid electrochromic devices. Conductivities for solid polymer electrolytes of various compositions of PEGMe, PMMA and LiClO4 were measured by impedance analysis techniques. Maximum ionic conductivities at room temperature were measured to be 6 x 10(-5) S/cm in the free standing film state for PMMA concentration of 17% w/w. The temperature dependence of ionic conductivity was described by VTF equations, which showed, to a certain PMMA content, that ionic transport in the polymer-salt complex was not significantly influenced by the presence of PMMA. The decrease in the overall ionic conductivity of PEGMe-PMMA blend with increasing PMMA concentration, was conceived as a dilution effect arising from the phase separation of PMMA.