Studies on the polymer electrolytes based on the PMMA ionomers

Abstract

A series of PMMA ionomer containing the different ion contents or ionic moieties in the polymer backbone was synthesized by solution polymerization and was characterized by DSC and FT-IR spectroscopy. The ionic moieties studied were alkali metal methacrylate and maleate units, were chosen on the purpose of investigation on the arrangement effects of the ionic units on the electrical properties in the ionomer electrolytes. The ionomers were blended with the ethylene carbonate(EC) and salts, LiClO4 to form the ionomer electrolytes films. The addition of EC bring about the mobility of charge carriers and solvation of charge carriers. The ion conductivities of the ionomer electrolytes were measured as a function of ion contents of the ionomer and temperatures for each series of the ionomer with different ionic units. The ion conductivities of the methacrylate ionomer electrolytes showed strong dependency on the ion content of ionomers and maximum conductivity at 5 mol% ion content of the ionomer electrolyte. The maximum ion conductivity found at 5 mol% ionomer electrolyte was interpreted in terms of compatibility between EC and ionomer, and ion aggregates formed in the ionomer electrolytes. The ion aggregates formed in the ionomer electrolytes was supposed to reduce the mobility of the charge carrier as well as the charge carrier concentration. It was also possible to quantify the mobility and the charge carrier concentration with suitable design of in-situ FT-IR spectroscopy. For the methacrylate ionomer electrolytes with various ion contents of the ionomer, the peculiar ion aggregates was found at 7 mol% ionomer electrolytes causing the abrupt decrease in the ion conductivity. A mechanism of the ion conduction in the ionomer electrolytes were also conducted by investigation of temperature dependency of ion conductivity. Some of the ionomer electrolytes showed VTF pattern which have been frequently reported in this filed, whereas the ionomer electrolytes contai...