Raman spectroscopic investigation of polybromide‐containing functional polymers

Solid polybromide‐containing functional polymers were obtained from basic anion‐exchange resins. The chloride or hydroxide anions of the commercial resins were exchanged by bromide, then dried under anaerobic conditions and allowed to react with a gaseous bromine phase. The formation of linear, slightly asymmetric tribromides was proved by Raman and far‐IR spectroscopy. The tribromide spectra are characterized by the symmetrical stretching vibration ν₁ at about 160 cm⁻¹ and the antisymmetric stretching vibration ν₃ at about 200 cm⁻¹. If the Br₂: Br⁻ molar ratio is greater than 1 an additional band could be observed at about 255 cm⁻¹. This band is assigned to the stretching vibration of coordinated bromine. It is shifted in the direction of free bromine at about 300 cm⁻¹ with increasing bromine content in the functional polymers. According to the spectroscopic results, the anion structure in amorphous polybromide‐containing functional polymers can be explained by tribromide ions and bromine molecules interacting with the tribromide. The thermal instability of higher polybromides was also proved spectroscopically.