Spectroscopic studies for molecular structure and complexation of silver polymer electrolytes

Polymer electrolytes containing silver ions have the potential to facilitate transport in membranes for separating olefin/paraffin mixtures. In the present study, the formation of AgBF4 and AgCF3SO3 complexes with poly(2-ethyl-2-oxazoline) (POZ) and poly(N-vinylpyrrolidone) (PVP) was investigated by spectroscopic methods. The carbonyl absorption bands of the infrared and Raman spectra of POZ and PVP with the silver salts confirm complex formation between silver ions and carbonyl oxygens. The symmetric stretching modes for SO3 of AgCF3SO3 complexed with PVP were analyzed in terms of "free" anions, ion pairs, and higher-order ion aggregates. The results suggest that the coordination number of silver ion with carbonyl oxygen of POZ and PVP is close to unity, demonstrating unusually high solubility of silver ions in the POZ and PVP matrices. Above the solubility limit, the ion pair and higher-order ion aggregates start to form.