Solid State Ionics, Vol.121, No.1-4, 91-99, 1999
Cation-anion and cation-polymer interactions in (PEO)(n)NaCF3SO3 (n=1-80)
Cation-anion interactions and cation-polymer interactions in the system (PEO)(n)NaCF3SO3 (1 less than or equal to n less than or equal to 80) have been studied using Raman and FTIR spectroscopy. In the dilute salt region (80 greater than or equal to n greater than or equal to 50) there are predominately 'free' ions and ion pairs present. However at increasing salt concentration, two aggregate species are observed. The symmetric SO3 stretching mode of one of the aggregate species appears at a frequency which is lower than that of the 'free' triflate anion (CF3SO3-), in contrast to behavior seen in the PEO-lithium triflate system. The cation-polymer interactions in high molecular weight PEO-sodium triflate do not appear to involve a local distortion of the -O-C-C-O- torsional angle, consistent with the crystal structure reported for the compound (PEO)NaCF3SO3. However such a distortion does appear to be present in the diglyme-sodium triflate system at salt concentrations n less than or equal to 20.