Cation-anion and cation-polymer interactions in (PEO)(n)NaCF3SO3 (n=1-80)

Cation-anion interactions and cation-polymer interactions in the system (PE O)(n)NaCF3SO3 (1 less than or equal to n less than or equal to 80) have bee n 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 predomina tely 'free' ions and ion pairs present. However at increasing salt concentr ation, two aggregate species are observed. The symmetric SO3 stretching mod e of one of the aggregate species appears at a frequency which is lower tha n that of the 'free' triflate anion (CF3SO3-), in contrast to behavior seen in the PEO-lithium triflate system. The cation-polymer interactions in hig h molecular weight PEO-sodium triflate do not appear to involve a local dis tortion of the -O-C-C-O- torsional angle, consistent with the crystal struc ture reported for the compound (PEO)NaCF3SO3. However such a distortion doe s appear to be present in the diglyme-sodium triflate system at salt concen trations n less than or equal to 20. (C) 1999 Elsevier Science B.V. All rig hts reserved.