Preparation,Characterization And Application Of Europium-polyurethane Composite Microspheres

The polymer microspheres containing luminescent rare earth ions have the characteristics of high luminescence performance of rare earth ions,microsphere stability and easy processing,which have broad application prospects in the field of microsphere materials research.Polyurethane is widely used in biomedicine and other fields because of its excellent physical properties and good biocompatibility.Polyurethane microspheres have the advantages of good adsorption capacity,excellent mechanical properties and good thermal stability,and can be used as supporting materials for drugs,proteins and biomolecules.At present,most researches on rare earth polymer concentrate on bulk phase materials,and rare earth polymer microspheres are rarely reported.In this work,monodisperse crosslinked polyurethane microspheres with carboxyl groups were prepared by precipitation polymerization using 2,2-dihydroxymethylpropionic acid（DMPA）and triphenylmethane triisocyanate（TTI）as monomers and dimethyl sulfoxide（DMSO）-acetone as solvent.The effects of mass ratio of mixed solvent DMSO/acetone,amount of monomer,polymerization time and polymerization temperature on the yield and particle size of microspheres were discussed,and the optimal experimental conditions were determined.Fourier transform infrared spectrometer,scanning electron microscope,ultraviolet/visible/near-infrared diffuse reflectometer,thermogravimetric analyzer and fluorescence spectrometer were used to characterize the microstructure and properties of the microspheres.The Eu（TTA）₃·2H₂O complex was synthesized with rare earth Eu Cl₃·6H₂O using thiophenyl trifluoroacetone（TTA）as ligand.Then,Eu@PUN composite microspheres were synthesized by using PUN microspheres as carrier and europium complex by adsorption method.Change the adsorption process of Eu（TTA）₃·2H₂O/proportion of PUN,adsorption time,adsorption temperature and conditions microspheres particle size and so on a series of experiments,the optimum adsorption conditions were determined.When the Eu（TTA）₃·2H₂O/PUN ratio was 0.6,9 h adsorption time,adsorption temperature 30℃ best adsorption effect,PUN microspheres for Eu（TTA）₃·2H₂O complexes of equilibrium adsorption quantity was 0.438 g/g.The adsorption process follows a quasi-second-order kinetic model,Langmuir and Freundlich isothermal adsorption model can reflect the PUN microspheres of Eu（TTA）₃·2H₂O adsorption process,The thermodynamic parameters of adsorption indicate that the process is a spontaneous exothermic process.Finally,it was found by fluorescence spectra that both the solid powder of Eu@PUN composite microspheres and its aqueous dispersion could emit characteristic peaks of Eu³⁺.The influence of excitation wavelength and concentration of microsphere aqueous dispersion on fluorescence properties was discussed.When Fe³⁺or Cr⁶⁺was added into the composite microsphere water dispersion,the fluorescence intensity of the system was weakened.The influence of different concentrations of Fe³⁺and Cr⁶⁺on the fluorescence intensity of the system was discussed,and the linear relationship between the two was established,and the detection limits of Fe³⁺and Cr⁶⁺were calculated.