A comparative infrared spectroscopic study has been undertaken in a system of poly(acrylonitrile)propylene carbonate-lithium triflate to examine the plasticizer interactions with the polymer and salt as well as ionic association. Lithium triflate is highly associated and the lithium ion interaction is stronger with propylene carbonate (PC) than with poly(acrylonitrile) (PAN). It is hypothesized that the local structure about the lithium ion is characterized by coordination with the three oxygen atoms of the PC molecule and a triflate anion oxygen, with a weak interaction with the C=N group of PAN.