Vibrational spectroscopy and structure of polymer electrolytes, poly(ethylene oxide) complexes of alkali metal salts

• Published in: The Journal of physics and chemistry of solids Vol. 42; no. 6; pp. 493 - 500
• Main Authors: Papke, B.L., Ratner, M.A., Shriver, D.F.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 1981
• ISSN: 0022-3697; 1879-2553
• DOI: 10.1016/0022-3697(81)90030-5

Complexes of poly(ethylene oxide) (PEO), with various alkali metal salts are known to exhibit ionic conductivities which exceed 10 −5(Ωcm) −1 at moderate temperatures. We have employed IR and Raman spectroseopy to study well characterized samples of the following polymer-salt complexes: PEO·NaBr, PEO·NaI, PEO·NaSCN, PEO·NaBF 4, PEO·NaCF 3SO 3, PEO·KSCN, PEO·RbSCN and PEO·CsSCN. Cation-dependent vibrational bands observed in the far IR and M-O n symmetric stretching bands observed in the Raman support a cation-oxygen atom interaction, and indicate the polyether chain may wrap around the cations. In particular, NaX and KX complexes of PEO are believed to have a helical configuration for the polymer which differs from that of pure PEO. Some general rules are presented for polymer-salt complex formation.