Rare Earth Metal Containing Polymers: Energy Transfer from Uranyl to Europium Ions in Ionomers

TLDR: In this paper, various ratios of Eu and UO2 acetates were prepared by dissolving Eu in acetic acid and removing acetic acids in vacuum, and fluorescence intensities at 616 nm were measured under excitation at wavelength of 429 nm.

Abstract: Various ratios of Eu and UO2 acetates were prepared by dissolving Eu and UO2 acetates in acetic acid and removing acetic acid in vacuum. The fluorescence intensities at 616 nm of these mixed acetates were measured under excitation at wavelength of 429 nm. Strong energy transfer from UO 2 2+ to Eu3+ was observed. This result indicated that these ions were in very close contact in this system. Various concentrations of Eu3+ and UO 2 2+ salts of polymers containing carboxyl ligands were prepared and fluorescence properties of these polymers were investigated. The polymers investigated were poly (methacrylic acid) (PMA), and copolymers of styrene-acrylic acid (PSAA) and methyl methacrylate-methacrylic acid (PMM/MA). When Eu3+ and UO 2 2+ were introduced to the polymers of PSAA and PMM/MA, very effective energy transfer from UO 2 2+ to Eu3+ was observed because of the proximity of these metal ions in ionic aggregates of these ionomers. However, the PMA-UO2 and Eu salts did not show energy transfer even when a large excess of UO2+ 2 was added to the polymer. The PMA salts are reported to have no ion aggregate structure; it is concluded that Eu3+ and UO 2 2+ ions were uniformly dispersed throughout the polymer system so that the distances between these ions were far beyond the energy transfer range.