Spectroscopic studies of luminescent and ionically conducting Eu[N(CF3SO2)2]3-PPG4000 complexes

Alternating current impedance, Fourier transform Raman/infrared (IR), and luminescence excitation (continuous and time-resolved) measurements have been conducted on solutions of poly(propylene glycol) (MW 4000) complexed with Eu[N(CF3SO2)(2)](3) salt, EuTFSI3, along with differential scanning calorimetry (DSC) studies. From observed frequency shifts of characteristic internal anionic vibrational modes (Raman and IR), we conclude that the salt is solvated by the polymer host. The TFSI anions, however, interact extensively with Eu3+ cations at all concentrations investigated. Ion-polymer interactions are manifested as changes in characteristic vibrational modes of the polymer. Continuous and time-resolved site-selective luminescence data give, respectively, evidence for two different types of chemical environments for solvated Eu3+ cations. In particular, D-5(0)-F-7(0) transition exhibits a structured two-component the strongly forbidden nondegenerate profile in the spectra. DSC data show that the lass transition temperature, T-g, is only marginally affected by the introduction of a relatively high concentration of salt into the host matrix, whereas the resulting polymer-salt complex is of rubbery character, distinctly different from the pure host polymer, which is a viscous liquid at room temperature. The present findings are interpreted in terms of a phase-segregated microstructure. This conjecture is supported by previous studies on PPG4000-based electrolytes indicating microscopic phase anomalies. (C) 1998 American Institute of Physics.