Preparation Of Rare Earth Doped Europium Complexes And Properties Of Temperature Sensitive Paints

Temperature sensitive paint measurement technology is a new temperature measurement technology,which uses fluorescent probe molecules as temperature sensors and measures the temperature distribution of the object surface based on the fluorescence temperature quenching mechanism.It is mainly applied to the quantitative measurement of the model surface temperature in the wind tunnel experiment.Fluorescent probe molecule is the core component of temperature sensitive paint,which is mainly composed of materials with high fluorescence intensity and good fluorescence temperature-quenching sensitivity.In this study,the fluorescent probe molecules Eu?p-MOBA?3phen and Eu?pMOBA?3bipy were synthesized using Eu³⁺ as the center ion,p-methoxybenzoic acid?pMOBA?as the first ligand,1,10-phenoline?phen?and 2,2?-bipyridyl?bipy?as the second ligand.Then the two probe molecules were doped with rare earth ions?Gd3+,La3+?to obtain Eu0.5Gd0.5?p-MOBA?3phen,Eu0.5La0.5?p-MOBA?3phen,Eu0.5Gd0.5?pMOBA?3bipy and Eu0.5La0.5?p-MOBA?3bipy.The six kinds of temperature sensitive paints were fabricated by mixing the fluorescent probe molecules with methyl methacrylate?MMA?and initiating polymerization with benzoyl peroxide?BPO?.The morphology,structure,luminescence properties of the fluorescent probe molecules,and the fluorescence temperature quenching property of the temperature sensitive paints were characterized by scanning electron microscopy,elemental analysis,UV-vis absorption spectra,infrared spectrometer and fluorescence spectra.The infrared spectrum,UV-vis absorption spectra and scanning electron microscopy spectrum show that Eu³⁺ was successfully coordinated with the ligands pMOBA and phen?bipy?,and the structure of Eu?p-MOBA?3phen and Eu?pMOBA?3bipy were not changed when doped with rare earth ions?Gd3+,La3+?,indicating that the doping of rare earth ions?Gd3+,La3+?partially replaced Eu³⁺.The fluorescence spectrum shows that the fluorescence intensity of Eu?p-MOBA?3phen is much greater than that of Eu?p-MOBA?3bipy because the phen ligand possesses higher energy transfer efficiency and better energy level matching due to its large degree of conjugation and rigidity.In addition,the temperature sensitive paints corresponding to the two fluorescent probe molecules have different temperature sensitivity,but the temperature sensitivity of Eu?p-MOBA?3bipy/PMMA is higher than that of Eu?pMOBA?3phen/PMMA in the temperature range from 50°C to 100°C,indicating that the temperature sensitivity of the temperature sensitive paint is not proportional to the fluorescence intensity.The addition of rare earth ions?Gd3+,La3+?have a gain effect on the luminescence of Eu?p-MOBA?3phen and Eu?p-MOBA?3bipy,and the fluorescence intensity of the fluorescent probe molecule doped with Gd3+ is higher than that doped with La3+,indicating that Gd3+ has a better sensitization effect on the fluorescence intensity of luminescent probes than La3+.The six temperature sensitive paints have different temperature sensitivity in the temperature range of 50??100?.According to the comprehensive analysis,Eu0.5La0.5?p-MOBA?3bipy/PMMA has higher temperature sensitivity in the temperature range of 60??70?,while Eu?pMOBA?3bipy/PMMA has higher temperature sensitivity in the temperature range of 50??60? and 70??100?.