Characterization of nanostructures of poly(ethylene oxide)-lithium triflate complex.

摘要

PEO was complexed with lithium triflate and confined under nanostructured conditions. Two configurations were investigated: the polymer was confined in pores on the nanometer scale, resulting in a sleeve of polymer in the pores; and the polymer was oriented as a thin film. Both structures allowed for an investigation into any change in polymer backbone ordering for the amorphous regions of the polymer and the study of the formation and effect of ordered crystalline regions. The confinement of PEO electrolytes in various nanopore sizes was seen to have effects on the thermal properties and, for all pore sizes, resulted in an increase in ionic conduction below the melt temperatures of the polymer during two successive heating cycles. Thermal analysis suggests that confinement originally results in a decrease in crystallinity. However, during the cooling process, there appears to be an increase in order in the confined samples. This order resulted in an additional increase in conductivity, suggesting that the crystalline regions play a more important role in conductivity than previously thought. Since the thickness of each sleeve was constant, the change related to pore size can be attributed to the pore difference in pore surface area geometry. To compliment this nanopore research, an unusual finding was discovered during through-film conductivity studies on the thin film. An increase in conductivity was seen in thickness between 400 nm and 2 microns; this may be attributed to a fluctuation in crystal growth rate.