Dielectric Relaxation in Poly(Ethylene Oxide) Complexed with Alkali Metal Perchlorates.

摘要

Audio frequency complex admittance measurements over the temperature range 5.5-350K have been performed on poly(ethylene oxide) (PEO) complexed with lithium and sodium perchlorates. No evidence of an (alpha)a relaxation was seen in any sample. In the Li-complexed material, the gamma relaxation occurs at about 174K and 1000 Hz which is the same as for pure PEO. In the Na-complexed materials, there appear to be more than one peak in this region, and the relative peak heights are concentration dependent. The result is that at the 8:1 doping level, there is a broad, skewed relaxation whose peak occurs at about 203K and 1000 Hz, while at 4.5:1 NaC104 the relaxation appears much closer to a normal peak with a maximum at 185K for the 1000 Hz data. Combined with previous results for thiocyanate complexed PEO, these results show that distortions in the polymer chain depend on both the cation and anion. Next, two new relaxations are observed at low temperatures. The first, occurring at 60-100 K is very weak and is common to all PEO samples. The second occurring at very low temperatures, is only found for percholate complexed PEO and is attributed to the localized motion of perchlorate-induced defects on the exterior of the chains. The high temperature electrical conductivity for PEO8:NaClO4 is found to be larger than PEO4.5:NaClO4 in agreement with the trend observed by other workers for PEO complexed with different alkali metal salts.