X-RAY ABSORPTION STUDIES OF PEO-ZNBR2 COMPLEXES

Polyethylene oxide (PEO)-ZnBr2 complexes, of the composition ZnBr2(PEO)8, were investigated by extended x-ray absorption fine structure spectroscopy in the temperature range 25 to 120-degrees-C. The results at all temperatures were very similar, and were consistent with the presence of largely undissociated ZnBr2 species that were coordinated with four oxygens from the PEO. The respective calculated Zn-Br and Zn-O bond lengths were 2.34 and 2.23 angstrom. There is evidence of some ZnBr2 dissociation at higher temperatures. A mechanism, based on Br- ion hopping between anchored species of ZnBr2 and ZnBr+ in PEO, is proposed to explain reported transport number and conductivity data.