Mediated Nitrogen Kong Polymers And Rare Earth Fluoride To Convert The Synthesis Of Luminescent Materials

In recent years, mesoporous materials and nanomaterials have attracted much attention owing to their specific properties and thus some breakthroughs applications in catalysis, energy, electrochemistry, biology and nanodevices. Current research efforts have been focused on the synthesis, modification, functional ization, applications and industrialization.On the other hand, upconversion luminescent materials with unique anti-stokes optical property have made considerable attention due to their enormous applications in luminescence, biological imaging and building blocks for optic devices. This thesis bases on the functionalization of mesoporous polymer materials and synthesis, modification of upconversion luminescent materials, including three parts:(1)synthesis of nitrogen-containing mesoporous polymers; (2) mesoporous silica encapsulating upconversion luminescence nanorods; (3)one-step hydrothermal method for water-dispersibility and carboxyl-functionalized upconversion materials.In chapter 2, ordered nitrogen-containing mesoporous carbonaceous polymers have been synthesized via a direct triblock-copolymer-templating process by using soluble, low-molecular-weight urea-phenol-formaldehyde (UPF) resin as an organic precursor and amphiphilic triblock copolymer Pluronic F127 as a template. The obtained nitrogen-containing mesoporous polymers possess ordered structures, high surface areas (385-420 m2/g), large pore sizes (3.1-3.6 nm), pore volumes (0.25-0.44 cm3/g), and high nitrogen content (2.69-2.94%). The structure and nitrogen content of the mesoporous polymers can be controlled by adjusting UPF/F127 ratios, urea content and the pre-polymerization time of UPF. Compared with the nitrogen-free mesoporous polymer, the obtained mesoporous carbonaceous polymers show more hydrophilic nature and thus evidently higher water adsorption capacity. The presence of nitrogen groups can also significantly improve the adsorption performance of Fe (Ⅲ) ions.In chapter 3, Triton X-100 is selected as an amphiphilic surfactant to modify the hydrophobic surface of theβ-NaYF4 nanorods into hydrophilic surface. The modified nanorods are coated with a thin silica layer through Stober method to form silica encapsulatingβ-NaYF4 nanorods. Then through a surfactant-templating sol-gel approach by using CTAB as a template, the mesostructured CTAB/silica composites are coated on the P-NaYF4@SiO2 nanorods.Finally, the CTAB templates are removed in a mild way of acetone extraction to obtain the mesoporous silica/rare-earth fluoride nanorods core-shell structures.The obtained silica shell mesostructure possesses uniform pore size(～2.3 nm) and opening channels.The thickness of the mesoporous silica shells can be adjusted in the range of 50-95 nm.The hexagonal phaseβ-NaYF4:Yb, Er nanorods cores with uniform mesoporous silica shells still show remarkable upconversion luminescence property. The surface property of the upconversionβ-NaYF4 nanorods can be changed after being coated with the porous silica. The mesoporous silica shells can provide a large venue for the effective modification of biomacromolecules, nanoparticles and organic dyes.Once the upconversion nanorods cores are excited by NIR light, the cores emit visible light due to upconversion, then visible light of the appropriate wavelength is absorbed by the Rhodamine B, which is loaded in the mesoporous silica shell and then the Rhodamine B is excited to emit fluorescence to accomplish secondary-excitation from the upconversion core to the fluorescence dyes. These properties may provide great applications in photo-inducing reaction, light-operated switch, and multiple light responses and so on.In chapter 4, we show a simple one-step hydrothermal method to synthesize water soluble and carboxyl-functionalized NaYF4:Yb/Er upconversion materials with shape-controlled by using small molecule binary acids such as malonic acid, oxalic acid, succinic acid and tartaric acid as chelating agents. The diverse morphologies including nanospheres, nanosheets, nanodisks, microtubes, microrods, hexagonal microprisms, polygonal columns and hexagonal tablets have been prepared under different condition such as reaction temperature, reaction time, the molar ratio of binary acid to sodium hydroxide and the kinds of binary acid. Moreover, we also investigated the surface property and upconversion luminescent capability of NaYF4: Yb/Er with different morphology. These results indicate that the obtained NaYF4: Yb/Er materials are water soluble and have carboxyl-functionalized surface and notable upconversion luminescence property.