Synthesis and luminescence properties of novel Eu-containing copolymers consisting of Eu(III)-acrylate-β-diketonate complex monomers and methyl methacrylate

Luminescent Eu-containing copolymers were synthesized through the copolymerization of Eu-complex monomers containing β-diketones with methyl methacrylate and characterized by FT-IR, UV-vis, XPS, GPC, TGA, and DSC. All these Eu copolymers are fully soluble in common organic solvents and can be cast into transparent, uniform, thin films with good mechanical flexibility and thermal stability. The Eu-copolymer luminophores exhibited intense red light at 615 nm under UV excitation at room temperature, which is attributed to the ⁵D₀→⁷F₂ transition of Eu(III) ions. The luminescence intensities, lifetimes and monochromaticities, η(⁵D₀→⁷F₂/⁵D₀→⁷F₁), of the Eu-copolymers are much higher than that of the corresponding Eu-complex monomers as well as Eu-complex/PMMA blends. Energy transfer processes and microenvironment effects were found to contribute to the improvement of the luminescence properties of the Eu-copolymers. A study of the dependence of emission intensities of the Eu-copolymers on the Eu content showed that the emission intensities increased nearly linearly with increasing Eu content, and no significant emission concentration quenching phenomenon was observed at the Eu content of 0-6.38 mol %. This indicates that the Eu-complex units in the Eu-copolymers are very uniformly bonded to the polymer chain, which is in good agreement with the result of polymer structure analysis.