Vibrational spectroscopic study of ionic association in poly(ethylene oxide)–NH4SCN polymer electrolytes

The polymer–ammonium complexes are an important class of proton conducting polymer electrolytes. In this work, poly(ethylene oxide) (PEO)–NH4SCN electrolytes were prepared over a large range of the salt content, and their FT-IR spectra were measured at room temperature. Based on the assignments of each band in the spectral envelope of SCN−1, their relative intensities are determined by the use of FT-IR technique. Following the experimental results and spectral analyses, this paper reports the interactions, the various ionic associations, the changes of the ionic association with NH4SCN content, and the characteristics of structure in PEO–NH4SCN electrolytes. It is shown that the hydrogen bonds of PEO and NH4SCN exert the great effect to the ionic association, the interactions of PEO with NH4SCN, and PEO crystallinity, in particular, under the condition of high NH4SCN content. In addition, the differences of ionic association among PEO–NaSCN, PEO–KSCN and NH4SCN electrolytes are also compared in this paper.