Photocuring Preparation And Characterization Of Rare Earth Bonded Silicone Luminescent Materials

The unique electronic structure and rich feature level of the rare earth elements endow the rare earth compound with excellent fluorescence properties. However, Rare earth ion transition that excitated by external energy is forbidden transition which resulting in faint luminescent efficiency of the rare earth ion. Hence, a kind of organic-ligand which could transfer the absorbed energy to the rare earth ions was chosen to sensitize the luminescence of the rare earth ions in order to solve the single elements luminescent inefficiency to enhance the specific fluorescence of the rare earth ions. The organic molecule which is chose to be the organic-ligand has good absorptivity, and can transfer energy to rare earth ions efficiently. But, the stability and machining performance of the rare earth complexes are poor, which limit its further application. An effective approach to solve this problem is to composite the complexes with a variety of matrices which have high stability to prepare hybrid material with good photophysical properties and machinability. At present, the matrixes commonly used in hybrid materials are divided into three categories:Inorganic matrix, Organic matrix and Organic-inorganic composite matrix. Since the inorganic matrix and organic matrix have limitations in the application process, therefore, Organic-inorganic composite matrix has become a popular choice for the rare earth hybrid materials.Physical doping and chemical bonding are two frequently used methods to prepare hybrid materials composed of rare earth complexes/organic-inorganic composite matrix. The concentration distribution of the bulk hybrid materials prepared by physical doping is nonuniform, which will cause concentration quenching. Moreover, the preparation method of the fluorescent microspheres used nowadays is to make the fluorescent substances disperse into the internal microspheres by physical doping, but the microspheres prepared by this method usually have many problems, such as the fluorescent substances are prone to leak from the interior of the microspheres, and the distribution of the substances is unequally. Compared to the physical doping method, the chemical bonding method has many advantages, such as well stability of the active ingredient, uniform distribution of the component, high doping amount of the functional active ingredient. However, the operation and process of using the chemical bonding method to prepare the hybrid materials are complicated, besides it has a longer reaction time. This research is based on the accumulation of the works which our groups did before, combined with the relevant reports at home and abroad, a method that organic silicone was used to copolymerize with the rare earth complexes by in-situ photopolymerization was proposed to prepare rare earth bonded bulk gel and fluorescent microspheres which the fluorescent substance bound to the surface of the microsphere. In particular, we carried out the researches below:(1)In our early research, we found that the UV radiation plays an active role in promoting the sol-gel process of the organic silicone, based on this research, we proposed a method that take advantage of the promotion of the UV radiation to the reaction of the both end of MAPTMS to prepare bonded fluorescent gel glass, and the bonding mechanism of the prepared fluorescent gel glass has been studied. First, we mixed the MAPTMS with Eu(AA)3 in the solution of DMSO, then the mixture was irradiated under a wavelength of 365 nm UV for 12 min to prepare the fluorescent gel glass. FT-IR, TGA, SEM, Fluorospectro photometer were used to characterize the bonding mechanism, thermal stability and morphology of the prepared sample. The results show that, the fluorescent gel glass in which the Eu is dispersed through coordination was prepared by covalent bond, the C=C of the Eu(AA)3 copolymerized with the C=C of the organic end of the ORMOSIL by the initiation of ultraviolet. The interior component of the prepared glass is homogeneous phase, and the thermal stability of the glass is good.(2)Based on the above work, a new method that take advantage of the promotion of the UV radiation to the reaction of the both end of MAPTMS was proposed to prepare surface bonded fluorescent silica microspheres. The surface properties of the fluorescent microspheres had been studied. First, we modified the surface of the silica microsphere by MAPTMS, then dispersed the microspheres in the ethanol, the Eu(AA)3 dissolved in DMSO was added into the ethanol, finally, the solution was irradiated under UV lamp at a wavelength of 365 nm for 10 min to prepare the fluorescent silica microsphere fast and conveniently. FT-IR, SEM, Contact angle measuring device, Fluorospectro photometer were used to characterize the bonding mechanism, morphology and fluorescent property of the prepared fluorescent microsphere. The results show that the Eu(AA)3 bonded on the surface of the silica microsphere is by chemical bonding, and the fluorescent propertv of the fluorescent silica microsphere is good.