Study On Synthesis And Fluorescent Property Of Rare Earth Luminescent Nanocomposites Based On Cellulose

Rare earth metals are strategic resource and their nanocomposites are used in a wide range of industry. Using the environmental friendliness biomass resources to prepare good rare earth metals nano luminescent material not only achieve high value utilization of biomass resources, but also meet the demand of the development of modern green chemistry. In this thesis, CMC/Tb or HPCMC/Tb nanoparticles were successfully synthesized using environmental friendliness materials, CMC, HPCMC and Tb3+ in waterbath or under microwave. The molecular structure was analyzed by FT-IR and XPS; SEM was used to observe the morphology; WAXD and TEM were applied to characterize the crystalline structure. The fluorescence property was investigated by UV-Vis and PL; TG and DSC were utilized to record the thermal performance. Main conclusions of this paper were summarized as follow:(1) In waterbath or under microwave, using ionic bond and coordination bonds, Tb3+ reacted with O atom of –COO-,-OH and –COC of CMC or HPCMC, and the partical size of products CMC/Tb or HPCMC/Tb could reach nanoscale.(2) The ultraviolet absorption of CMC/Tb and HPCMC/Tb nanoparticles came from macromolecule ligand, CMC and HPCMC, which were the energy giver of Tb3+ and made its fluorescence senstized. All product exhibited typical fluorescence emission spectra of Tb3+, which consist of the characteristic transitions from 5D4â†'7F6(489 nm), 5D4â†'7F5(545 nm), 5D4â†'7F4(584 nm) and 5D4â†'7F3(619 nm), and the half peak width of the strongest green fluorescence of 5D4â†'7F5 was less than 10 nm.(3) The CMC/Tb nanocomposites were all influenced by p H, ratio of CMC to Tb3+ and reaction time. In this thesis, in waterbath, the best fluorescence performance were under the condition of pH=8, CMC:Tb=5:1(wt:wt), 30 min and 70℃. Under microwave, the best fluorescence performance were under the condition of pH=8, CMC:Tb=1.65:1(wt:wt), 10 min and 70℃.(4) The HPCMC/Tb nanocomposites were all influenced by p H and reaction time. In this thesis, in waterbath, the best fluorescence performance were under the condition of pH=8, HPCMC:Tb=20:1, 60 min and 70℃. Under microwave, the best fluorescence performance were under the condition of pH=7, HPCMC:Tb=20:1(wt:wt), 15 min and 70℃. Under such condition, the CMC/Tb or HPCMC/Tb possessed small grain size, homogeneous dispersion and higher fluorescence.(5) Compared with waterbath heating mode, in high p H, the microwave heating mode can easily improve the ability of –COO- of CMC to react with Tb3+, change the morphology of mesoscopic structures and improve fluorescence intensity. HPCMC, with longer side chains, can easily react with Tb3+ than CMC, and its stronger crystalline structure also improve the fluorescence intensity.