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Eu3+, Tb3+, and Co2+ salts of polymers containing carboxylic acid and sulfonic acid ligands were prepared and characterized. The polymers investigated were poly(acrylic acid) (PAA), copolymers of styrene-acrylic acid (PSAA), styrene-maleic acid (PSM), and methyl methacrylate-methacrylic acid (PMM/MA), and partially carboxylated and sulfonated polystyrenes (CPS and SPS). The lanthanide salts of these polymers showed characteristic lanthanide ion fluorescence in the solid state on excitation with UV light. The fluorescence excitation and emission spectra of these salts excepting carboxylated polystyrene showed characteristic spectra of the free ions, indicating that no energy is transferred from the polymer matrix to the ions. The carboxylated polystyrene-Eu3+ and -Tb3+ showed broad excitation spectra similar to the spectrum of the polymer and emission from the lanthanide ions, suggesting energy transfer from the polymer to the ion. The fluorescence intensities of the lanthanide salts of PAA, PSM, CPS, and SPS were found to increase linearly with the metal ion content. However, the salts of PSAA and PMM/MA displayed typical fluorescence concentration quenching behavior, reaching a maximum at 4-6 wt % of metal and decreasing with further increases in metal content. These results suggest that PSAA and PMM/MA contain ionic aggregates in which Eu and Tb ions are located close together. The energy transfer from Tb3+ to Co2+ and Eu3+ was evaluated from the Tb3+ fluorescence quenching. This was much more efficient in PSAA than in CPS and SPS systems.These results confirm that ion aggregates exist in PMM/MA and PSAA but not in the CPS and SPS systems at low metal concentration (<6 mol %). The probability Pd~a of dipole-dipole transfer between Tb3+ and Co2+ statistically distributed in a polymer matrix and the quenching characteristics were calculated by using Forster's equation. Experimental fluorescence quenching behaviors for PASS, CPS, and SPS are discussed as compared with the calculated quenching curve.

Rare earth metal (Dy3+, Er3+, Eu3+, and Sm3+) salts of copolymers of methyl methacrylate–methacrylic acid, styrene–acrylic acid, 1‐vinylnaphthalene–acrylic acid and 1‐vinylanthracene–styrene–acrylic acid were prepared. The fluorescence of these polymer salts under ultraviolet excitation was investigated. The fluorescent intensity of polymer–Eu3+ films varied with film thickness because of incomplete absorption of exciting light, hence most of the measurements were made on pressed fine powders. The fluorescent intensity of mixed samples of Eu(III) acetate in a polymer matrix increased linearly with Eu content. However, the Eu3+–polymer complex system displayed typical concentration‐quenching behavior, reaching a maximum at 4–5 wt % Eu and decreasing with further increases in Eu content. This suggests that the ionomer contains ionic aggregates, in agreement with a recently proposed model. Such aggregates would create locally high Eu ion concentrations, whose interactions lead to concentration quenching at low nominal concentrations. The fluorescent intensity of the acrylic copolymers decrassed in the order methacrylate > styrene > naphthalene > anthracene. This sequence is explained by incrasing competition for the exciting light by the aromatic groups with negligible energy transfer from the aromatic groups to the Eu3+ ions. This is also consistent with the hypothesis that the ionic regions of the polymer are segregated.

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