Evidence of dissolved ions and ion pairs in dilute poly (propylene oxide)-salt solutions

Abstract To test previous interpretations of splitted Raman modes in terms of solvated “free” ions and ion pairs in polyether-salt complexes we have carried out Raman measurements of poly(propylene oxide) (PPO) containing MClO 4 and MCF 3 SO 3 ( M = Li or Na), respectively, from the low concentrations L : M = 1000 ( O : M is the oxygen to salt ratio) previously not investigated to the range O : M ≈ 30−5 in which most reported spectral measurements have been carried out.