Infrared spectroscopic study of solid films of poly(ethylene glycol) doped with cations

The infrared spectra of solid films, prepared on a silicon plate of poly(ethylene glycol) doped with various cations (Li⁺, Na⁺, K⁺, Ca²⁺ and Ba²⁺), have been measured. The spectral analysis indicates that the films are non-crystalline and essentially amorphous. The polymer chain is significantly disordered by assuming diverse conformational states. The interaction between the ether oxygens of the polymer and the cation, as estimated from the C---O stretching wavenumber, is correlated to the size of the cation; the interaction is stronger for the cation with larger size.