In Situ Preparation And Luminescent Properties Of RE/Silica Hybrid Materials

Rare earth complexes with organic ligands have excellentluminescence properties such as high fluorescent efficiency, narrow bandemission spectra, which can be widely used in the fields of light-emittingmaterials, military and medical science. With the development of scienceand technology, unitary nature of the materials can not meet the demands,and it is urgent to develop new materials. An important way is to hybridtwo or more functional materials to obtain hybrid materials with excellentproperties. In this thesis, two kinds of RE/Silica hybrid materials,RE/mesoporous SBA-15, RE/SiO2nanospheres have been synthesizedand characterized. The luminescent properties of hybrid materials havealso been investigated.A series of mesoporous SBA-15with different pore size wereprepared via hydrothermal method with Pluronic P123as the template,TMB or n-hexane as pore-enlarging agent. The mesoporous structure ofSBA-15was characterized by XRD, nitrogen adsorption-desoptionmeasurements, and IR spectra. The results show that SBA-15has typicalordered mesoporous structure and the pore sizes of SBA-15can be variedfrom3to6nm. The surface of SBA-15was further modified by APTESand trimellitic anhydride to obtain carboxyl-modified SBA-15. Thecarboxyl-modified SBA-15in situ coordinate with the rare earth ions(Eu3+, Tb3+) to afford luminescent RE/SBA-15hybrid materials. Thehybrid materials were characterized by nitrogen adsorption-desoptionmeasurements and FTIR. The results showed that Tb3+or Eu3+could beincorporated into the channels of mesoporous SBA-15. The luminescentproperties of the RE/SBA-15hybrid materials were investigated byexcitation and emission spectra. The results show that the hybridmaterials could emit strong luminescence with high color purity andefficiencyThe process of preparing highly monodispersed luminescent SiO2 nanospheres containing covalently bonded Eu3+(Tb3+) trimelliticanhydride complexes was described in chapter4. Firstly, SiO2nanospheres were prepared via Stober sol-gel method with ammoniawater as the catalyst, TEOS as materials, and further surface modified byAPTES, then reaction with trimellitic anhydride to obtaincarboxyl-modified silica nanospheres. With changing the amount of thecatalyst, the silica nanospheres with an average diameter (30-100nm)were obtained. Secondly, the carboxyl-modified silica nanospheres in situcoordinate with the rare earth ions (Eu3+, Tb3+) to afford luminescentnanospheres SiO2@Tb, SiO2@Eu. The monodispersed luminescentnanospheres containing covalently bonded Eu3+(Tb3+) trimelliticanhydride complexes were characterized by TEM and FTIR. The resultsshowed that Eu3+(Tb3+) was connected with the surface of SiO2nanospheres via chemical bond by IR spectra. The luminescent propertiesof the nanospheres were investigated by excitation and emission spectra.Particularly, a very interesting phenomenon was found that thenanosphere with low content of lanthanide ion could emit dramaticallystronger luminescence than the pure lanthanide complex. The compositematerial of PMMA and SiO2@Eu was prepared by blending of SiO2@Euand PMMA in solution. The film of the PMMA/SiO2@Eu was obtainedby spin-coating method and characterized by excitation and emissionspectra and UV. The results showed that the film was transparent andcould emit strong luminescence with high color purity and efficiency.