Broad-band dielectric and conductive spectroscopy covering a 10 mHz-10 MHz frequency range has been employed to examine both the ionic and dipolar motions in a single-ion conducting copolymer of nona-oxyethylene methacrylate and alkali-metal methacrylate, P(MEO9-MAM) with M = Li, Na, and K. Analysis of the observed spectra revealed an existence of three dielectric relaxation processes associated with the dipolar motions in the methacrylate main chains (α) and oxyethylene side chains (β,γ). On the low frequency side of the α process an additional process α′ was observed that was attributed to a local ionic fluctuation in a heterogeneous medium. Its relaxation frequency depended upon the ionic species and increased in the order of Li<Na<K in parallel with an increase of dc conductivity σdc. Comparing the temperature dependence of σdc and the relaxation frequencies of these processes, we conclude that the main-chain motion governs σdc through the dissociation of metal ions at low temperatures and spatial heterogeneity as well as the side-chain motion governs the ionic mobility at high temperatures.
|Number of pages||6|
|Publication status||Published - 3 Jan 2000|
|Event||Proceedings of the 1998 6th International Symposium on Polymer Electrolytes (ISPE-6) - Hayama, Jpn|
Duration: 1 Nov 1998 → 6 Nov 1998