Effect of substituent groups with two types on benzene ring on photoluminescence property of complexes of benzoic acid—Functionalized polystyrene with Eu(III) Ion

Effects of Europium Complex on Thermal and Photoluminescence Properties of Polyurethane-Europium Materials

A europium complex with double bonds was synthesized with crotonic acid as the ligand and a europium ion as the center ion. Then, the obtained europium complex was added to synthesized poly(urethane-acrylate) macromonomers to prepare the bonded polyurethane-europium materials by the polymerization of the double bonds in the complex and the poly(urethane-acrylate) macromonomers. The prepared polyurethane-europium materials had high transparency, good thermal stability and good fluorescence. The storage moduli of polyurethane-europium materials are obviously higher than those of pure polyurethane. Polyurethane-europium materials exhibit bright red light with good monochromaticity. The light transmittance of the material decreases slightly with increases in the europium complex content, but the luminescence intensity gradually increases. In particular, polyurethane-europium materials possess a long luminescence lifetime, which has potential applications for optical display instruments.

Eu3+- and Tb3+-Based Coordination Complexes of Poly(N-Isopropyl,N-methylacrylamide-stat-N,N-dimethylacrylamide) Copolymer: Synthesis, Characterization and Property

This contribution reports the syntheses, structural analyses and properties of europium (Eu³⁺)- and terbium (Tb³⁺)-based coordination complexes of poly(N-isopropyl,N-methylacrylamide-stat-N,N-dimethylacrylamide) (poly(iPMAm-stat-DMAm)) copolymer, named as poly-Eu(III) and poly-Tb(III), respectively. In greater detail, poly(iPMAm₈₅-stat-DMAm₁₅) is first prepared by random copolymerization of N-isopropyl,N-methylacrylamide (iPMAm) and N,N-dimethylacrylamide (DMAm) via group transfer polymerization (GTP). Next, poly(iPMAm₈₅-stat-DMAm₁₅) is used as the polymer matrix for chelating with Eu³⁺ and Tb³⁺ cations at its side amide groups, to produce poly-Eu(III) and poly-Tb(III). Their structural characterizations by FT-IR spectroscopy and XPS confirm the formation of polymeric complexes. The study on their fluorescence emission characteristics and luminescence lifetime demonstrates that Poly-Eu(III) shows four strong emission peaks at 578, 593, 622, and 651 nm, which are responsible for the electron transitions from the excited ⁵D₀ state to the multiplet ⁷F_J (J = 0, 1, 2, 3) states, respectively, and poly-Tb(III) also displays four emission peaks at 489, 545, 588, and 654 nm, mainly due to the electron transitions of ⁵D₄ → ⁷F_i (i = 6, 5, 4, 3). The luminescence lifetimes of poly-Eu(III) (τ_poly-Eu(III)) and poly-Tb(III) (τ_poly-Tb(III)) are determined to be 4.57 and 7.50 ms, respectively. In addition, in aqueous solutions, poly-Eu(III) and poly-Tb(III) are found to exhibit thermoresponsivity, with their cloud temperatures (T_cs) locating around 36.4 and 36.8 °C, respectively. Finally, the cytotoxicity study on the human colon carcinoma cells LoVo and DLD1 suggests that the luminescent Eu³⁺ and Tb³⁺ in the chelated state with poly(iPMAm-stat-DMAm) show much better biocompatibility and lower toxicity than their inorganic salts.

Effect of γ-irradiation on optical properties of Eu2 O3 -doped polystyrene polymer films

In the present study, europium (III) oxide (Eu₂ O₃ )-doped polystyrene (PS) polymer films were synthesized using a solution-casting technique for different filler levels. These films were irradiated with 5, 25 and 50 kGy γ doses and characterized using various techniques, viz. X-ray diffraction (XRD), and UV-visible and photoluminescence (PL) spectroscopies as a function of composition level and radiation dose. The UV-visible spectra indicated a decrease in the optical direct band gap of composite films with increasing concentrations of dopant and radiation dose. The band gaps of composites obtained using Tauc's equation were found to be 4.38, 4.37, 4.36 and 4.34 eV for 0, 1, 3 and 5% Eu₂ O₃ -doped PS respectively, while the band gaps of 5% Eu₂ O₃ -doped PS polymer films irradiated with 5, 25 and 50 kGy were found to be 4.30, 4.26 and 4.21 eV, respectively. Photoluminescence (PL) emission spectra showed the characteristic peaks of Eu³⁺ at 595 nm, 612 nm and 617 nm with an excitation wavelength of 247 nm. The intensity of characteristic peaks of Eu³⁺ was observed to increase with increasing filler concentration, while it was found to decrease with increasing radiation dose. The polymer under study may be useful in accidental dosimetry. As photoluminescence studies are carried out after a gap of 200 h from irradiation and PL emission of γ-irradiated polymer yielded 10 times emission when compared with non-irradiated polymer.