Ultraviolet / Blue Light Enhanced Rare Earth Nanocomposites, Preparation Method and Application in Acrylate Photopolymerization

Abstract

The present invention discloses a UV / blue light enhanced rare earth nanocomposite, a preparation method thereof, and an application thereof in acrylate photopolymerization. The rare earth nanocomposite includes rare earth nanomaterials and an organic coordination molecular layer disposed on the surface of the rare earth nanomaterials; the rare earth nanomaterials include a light emitting layer and a first energy capture layer disposed outside the light emitting layer, and an energy transfer channel is formed between the first energy capture layer and the light emitting layer; the main component of the organic coordination molecular layer is picolinic acid. In the rare earth nanocomposite of the present invention, the light emitting layer is used to capture energy and emit light, and the first energy capture layer is used to additionally obtain excitation energy and transfer it to the light emitting layer, thereby improving the excitation light energy capture ability, increasing the light emission intensity, promoting the photopolymerization reaction, and achieving the purpose of improving the photopolymerization reaction effect. Picolinic acid is used to protect the surface of the rare earth nanocomposite and promote energy transfer, thereby enhancing the photopolymerization reaction effect.

Description

Technical Field

[0001] The present invention relates to the technical field of 3D printing materials, and in particular, to an ultraviolet / blue light enhanced rare earth nanocomposite material, a preparation method thereof, and an application thereof in acrylate photopolymerization. Background Art

[0002] Lanthanide (Ln 3+ ) doped nanomaterials have the characteristics of narrow emission bands, good chemical stability, long emission lifetimes, low photobleaching, low toxicity, and strong penetration ability. And Ln 3+ has rich energy levels, so that its absorption and emission spectra can cover the region from ultraviolet to near infrared. Therefore, such materials show excellent application values in photocatalysis, optical storage, anti-counterfeiting, and photoinduced polymer polymerization reactions. Although the doped lanthanide nanomaterials have rich emission spectral bands, it is still a major challenge to achieve efficient upconversion luminescence in the ultraviolet / blue light region. This challenge hinders their practical applications in various fields. In recent years, core-shell structure engineering has been proven to be an effective material design method, which can greatly improve the luminescence intensity from ultraviolet to near infrared, especially in the deep ultraviolet / blue light region, thereby expanding the application scope of rare earth nanomaterials.

[0003] The photopolymerization process is widely used in various fields of science, industry, and technology, including direct laser writing, three-dimensional micromachining, holography, microelectronics and optoelectronics, optical element formation, data recording and storage, etc. Generally, this means that a liquid mixture of a photopolymerizable monomer or oligomer and a photoinitiator (referred to as a photocurable composition or PCC) is converted into a solid material under light irradiation. The light-based trigger is the key advantage of this technology, which allows high spatial and temporal resolutions to be achieved in a non-contact manner. Single-photon polymerization is usually activated by ultraviolet or blue light irradiation, but lacks the repetitive step of adding subsequent polymer layers, so it is mainly applicable to the manufacture of two-dimensional structures. This limitation is attributed to the limitations of time and space. First, the high light absorption rate of the photoinitiator leads to the formation of stable free radicals and the immediate triggering of the polymerization process. In addition, the existing rare earth nanocomposites have only single-phase energy transfer channels, and the penetration depths of ultraviolet and visible light are limited by exponential light attenuation to the shallow surface layer, resulting in poor photopolymerization reaction effects. The linear light absorption limits the direct generation of 3D bulk structures with uniform density. Summary of the Invention

[0004] The present invention provides an ultraviolet / blue light enhanced rare earth nanocomposite material, a preparation method thereof, and an application thereof, so as to solve the technical problem of poor photopolymerization reaction effects of existing rare earth nanocomposite materials.

[0005] According to a first aspect of the present invention, there is provided an ultraviolet / blue light enhanced rare earth nanocomposite, wherein the rare earth nanocomposite comprises rare earth nanomaterials and an organic coordination molecular layer disposed on the surface of the rare earth nanomaterials; the rare earth nanomaterials comprise a light-emitting layer and a first energy capture layer disposed outside the light-emitting layer, and an energy transfer channel is formed between the first energy capture layer and the light-emitting layer;

[0006] The main component of the organic coordination molecular layer is picolinic acid;

[0007] The light-emitting layer is a material containing Yb 3+ , Tm 3+ , or a material containing Yb 3+ , Gd 3+ , Tm 3+ , or a material containing Yb 3+ , Er 3+ , or a material containing Gd 3+ , Tm 3+ , Ce 3+ , or at least one of the above materials;

[0008] The first energy capture layer is a material containing Yb 3+ , a material containing Nd 3+ , a material containing Er 3+ , or at least one of the materials containing Yb 3+ , Nd 3+ simultaneously;

[0009] Further, the rare earth nanomaterials further comprise a second energy capture layer disposed inside the light-emitting layer, and an energy transfer channel is formed between the second energy capture layer and the light-emitting layer;

[0010] The second energy capture layer is a material containing Yb 3+ , a material containing Nd 3+ , a material containing Er 3+ , or at least one of the materials containing Yb 3+ , Nd 3+ simultaneously;

[0011] Further, the thickness of the second energy capture layer is 5 - 40 nm;

[0012] The thickness of the light-emitting layer is 2 - 10 nm;

[0013] The thickness of the first energy capture layer is 2 - 10 nm.

[0014] Further, the matrix materials of the second energy capture layer, the light-emitting layer and the first energy capture layer are ALnF 4 or AF 2, where A is Li, Na, K or Ca; Ln is La, Lu, Yb, Gd or Y.

[0015] Further, the mole fraction of Yb 3+ ions in the second energy capture layer is 90% - 100%, or the mole fraction of Nd 3+ ions is 50% - 100%, or the mole fraction of Er 3+ ions is 90% - 100%.

[0016] The mole fraction of Yb 3+ ions in the light-emitting layer is 30% - 70%, and / or the mole fraction of Tm 3+ ions is 0.2% - 1.5%, and / or the mole fraction of Er 3+ ions is 0.2% - 3%, and / or the mole fraction of Gd 3+ ions is 40% - 60%, or the mole fraction of Ce 3+ ions is 0.2% - 5%.

[0017] The mole fraction of Yb 3+ ions in the first energy capture layer is 5% - 20%, and / or the mole fraction of Nd 3+ ions is 1% - 20%, or the mole fraction of Er 3+ ions is 1% - 25%.

[0018] According to the second aspect of the present invention, there is also provided an application of the ultraviolet / blue light enhanced rare earth nanocomposite in acrylate photopolymerization.

[0019] Further, the rare earth nanocomposite is used to prepare 3D printing materials.

[0020] Further, the preparation of the 3D printing material includes the following steps:

[0021] Mix the rare earth nanocomposite with a photocurable composition to form a liquid prepolymer; the prepolymer is the 3D printing material.

[0022] According to the third aspect of the present invention, there is also provided a preparation method of an ultraviolet / blue light enhanced rare earth nanocomposite, including the following steps:

[0023] S1: Prepare rare earth nanomaterials;

[0024] S2: Remove the surface ligands of the rare earth nanomaterials to obtain ligand-free rare earth nanomaterials, add a pyridine-2-carboxylic acid solution to the solution of the ligand-free rare earth nanomaterials, and perform centrifugation to obtain the rare earth nanocomposite.

[0025] Further, the preparation of the rare earth nanomaterials includes the following steps:

[0026] S1.1: Dissolve rare earth salt A in a solvent to obtain precursor A; react precursor A under the conditions of a sodium source and a fluorine source to obtain a second energy capture layer;

[0027] S1.2: Dissolve rare earth salt B in a solvent to obtain precursor B; mix the second energy capture layer with precursor B, and in the presence of a sodium source and a fluorine source, wrap the second energy capture layer to obtain a core-shell structure nanocrystal containing the second energy capture layer and a light-emitting layer;

[0028] S1.3: Dissolve rare earth salt C in a solvent to obtain precursor C; mix the core-shell structure nanocrystal with precursor C, and in the presence of a sodium source and a fluorine source, wrap the core-shell structure nanocrystal to obtain a rare earth nanomaterial with a core-shell-shell structure composed of a second energy capture layer, a light-emitting layer, and a first energy capture layer from the inside out.

[0029] The present invention has the following beneficial effects:

[0030] The rare earth nanocomposite material of the present invention includes a rare earth nanomaterial and an organic coordination molecular layer disposed on the surface of the rare earth nanomaterial. Among them, the light-emitting layer in the rare earth nanoparticles is used to capture energy and emit light, and the first energy capture layer is used to additionally obtain excitation energy and transfer it to the light-emitting layer, forming an energy transfer channel, thereby improving the excitation light energy capture ability, reducing the loss of excitation energy on the surface, increasing the light emission intensity, promoting the photopolymerization reaction, and achieving the purpose of improving the photopolymerization reaction effect; the pyridine-2-carboxylic acid molecules of the organic coordination molecular layer are rigid structures, which can inhibit the interaction between rare earth ions on the surface of the rare earth nanomaterial and solvent molecules, and inhibit the quenching caused by surface defects or vacancies, greatly reducing multi-phonon non-radiative transitions. In addition, the N,O-hybrid coordination sites in the molecules form coordination bonds with rare earth ions on the surface of the rare earth nanomaterial, so that the energy gap between the occupied electron orbitals and the empty orbitals of the rare earth ions on the surface of the rare earth nanomaterial is equivalent to the energy gap of the rare earth ions inside the rare earth nanomaterial, which can promote the energy transfer from the outside to the inside and further improve the light emission efficiency.

[0031] The rare earth nanocomposite material of the present invention can generate efficient upconversion emission in the ultraviolet / blue light spectral range under the excitation of near-infrared light such as ~740 nm, ~793 nm, ~808 nm, ~980 nm or ~1532 nm, greatly increasing the upconversion light emission intensity of ultraviolet / blue light, thereby improving the photopolymerization reaction effect to meet the requirements of rapid prototyping of high molecular polymers induced by ultraviolet / blue light.

[0032] In addition to the purposes, features and advantages described above, the present invention has other purposes, features and advantages. The present invention will be further described in detail below. Description of the Drawings

[0033] The accompanying drawings, which form a part of this application, are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0034] Figure 1 For the NaYbF in Example 1 of the present invention 4 @NaGdF 4 :Yb,Tm@NaLuF 4 :Yb transmission electron microscope photograph of nanoparticles;

[0035] Figure 2 For the NaYbF in Example 1 of the present invention 4 @NaGdF 4 :Yb,Tm@NaLuF 4 :Yb high-angle annular dark field (HAADF) scanning transmission electron microscope (STEM) image of the nanomaterial;

[0036] Figure 3 Emission spectrum of the multiphase energy-capturing rare earth nanomaterial in Example 1 of the present invention;

[0037] Figure 4 Emission intensity comparison spectrum of the rare earth nanomaterial in Example 1 of the present invention and the nanomaterial modified with pyridine-2-carboxylic acid in Example 2;

[0038] Figure 5 Schematic diagram of energy transfer of the unmodified and pyridine-2-carboxylic acid layer-modified nanomaterials;

[0039] Figure 6 3D printed form finally obtained in Example 5 of the present invention. Detailed Description of the Invention

[0040] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings, but the present invention can be implemented in many different ways defined and covered by the following.

[0041] An embodiment of the first aspect of the present invention provides an ultraviolet / blue light enhanced rare earth nanocomposite, the rare earth nanocomposite comprising a rare earth nanomaterial and an organic coordination molecular layer disposed on the surface of the rare earth nanomaterial; the rare earth nanomaterial includes a light-emitting layer and a first energy capture layer disposed outside the light-emitting layer, and an energy transfer channel is formed between the first energy capture layer and the light-emitting layer;

[0042] The main component of the organic coordination molecular layer is pyridine-2-carboxylic acid, and pyridine-2-carboxylic acid forms a coordination bond with the rare earth ions of the first energy capture layer to promote energy transfer.

[0043] The light-emitting layer is Yb-containing3+ , Tm 3+ materials, or containing Yb 3+ , Gd 3+ , Tm 3+ materials, or containing Yb 3+ , Er 3+ materials, or containing Gd 3+ , Tm 3+ , Ce 3+ at least one of the materials;

[0044] The first energy capture layer is a material containing Yb 3+ , a material containing Nd 3+ , a material containing Er 3+ , or simultaneously containing Yb 3+ , Nd 3+ at least one of the materials.

[0045] The rare earth nanocomposite material of the present invention comprises rare earth nanomaterials and an organic coordination molecular layer disposed on the surface of the rare earth nanomaterials. The luminescent layer in the rare earth nanoparticles is used for capturing energy and emitting light. The first energy capture layer is used for additionally obtaining excitation energy and transferring it to the luminescent layer, forming an energy transfer channel, thereby improving the excitation light energy capture ability, reducing the loss of excitation energy on the surface, increasing the luminescence intensity, promoting the photopolymerization reaction, and achieving the purpose of enhancing the photopolymerization reaction effect. The pyridine-2-carboxylic acid molecules of the organic coordination molecular layer are of a rigid structure, which can inhibit the interaction between the rare earth ions on the surface of the rare earth nanomaterials and the solvent molecules, and inhibit the quenching caused by surface defects or vacancies, greatly reducing the multi-phonon non-radiative transition. In addition, the N,O-hybrid coordination sites in the molecules form a five-membered chelate ring with the rare earth ions on the surface of the first energy capture layer of the rare earth nanomaterials, such as Yb³⁺ ions. The hybrid orbitals formed thereby increase the 4f energy level occupied by the surface rare earth ions and reduce their empty 4f energy level. Therefore, the energy gap between the occupied electron orbitals and the empty orbitals of the rare earth ions in the first energy capture layer is equivalent to the energy gap of the rare earth ions in the luminescent layer and the second energy capture layer inside the rare earth nanomaterials, which can promote the energy transfer from the outside to the inside and further improve the luminescence efficiency.

[0046] In a preferred embodiment, the rare earth nanomaterials further comprise a second energy capture layer disposed inside the luminescent layer, and an energy transfer channel is formed between the second energy capture layer and the luminescent layer. The second energy capture layer is a material containing Yb 3+ , a material containing Nd 3+ , a material containing Er 3+ , or simultaneously containing Yb 3+ , Nd 3+At least one of the materials. The rare earth nanomaterial has a core-shell-shell structure, with a second energy capture layer, a luminescent layer, and a first energy capture layer from the inside out. Under the excitation of near-infrared light, the second energy capture layer and the first energy capture layer can simultaneously absorb energy and transfer it to the middle luminescent layer, forming a two-phase energy transfer channel, thereby realizing enhanced luminescence from ultraviolet to visible light regions in the rare earth nanocomposite and further improving the photopolymerization effect.

[0047] Preferably, the thickness of the second energy capture layer is 5 - 40 nm; the thickness of the luminescent layer is 2 - 10 nm; the thickness of the first energy capture layer is 2 - 10 nm.

[0048] In the core-shell-shell structure rare earth nanoparticles, the luminescent layer is doped with a sensitizer and a luminescence center for energy capture and luminescence. The second energy capture layer and the first energy capture layer are also doped with a certain concentration of sensitizer for additional acquisition of excitation energy. The second energy capture layer and the first energy capture layer transfer energy to the luminescent layer, thus forming a two-phase energy transfer channel. The sensitizer includes Yb 3+ 、Nd 3+ 、Er 3+ etc. At the same time, Yb 3+ 、Nd 3+ 、Er 3+ can also act as luminescence centers. The luminescence center is an ion that can receive energy and convert the received energy into light, such as Yb 3+ 、Nd 3+ 、Er 3+ etc. The near-infrared light is infrared light with wavelengths of 740 nm, ~793 nm, ~808 nm, ~980 nm, ~1532 nm, etc. The preferred grafting amount of the organic coordination molecular layer is 500 - 10000 molecules per surface of each core-shell-shell structure rare earth nanoparticle. The present invention constructs an efficient energy transfer channel using the organic coordination molecular layer and the core-shell-shell structure rare earth nanoparticles, ultimately achieving the purpose of enhanced ultraviolet / blue light, thereby improving the photopolymerization effect.

[0049] In the embodiments of the present invention, the matrix materials of the second energy capture layer, the luminescent layer, and the first energy capture layer are ALnF 4 or AF 2 , where A is Li, Na, K, or Ca; Ln is La, Lu, Yb, Gd, or Y. The matrix materials of the second energy capture layer, the luminescent layer, and the first energy capture layer are selected according to specific requirements and can be the same or different.

[0050] In the embodiments of the present invention, Yb in the second energy capture layer 3+The mole fraction of the ions is 90% - 100%, or Nd 3+ The mole fraction of the ions is 50% - 100%, or Er 3+ The mole fraction of the ions is 90% - 100%.

[0051] In the second energy trapping layer, the concentration of Yb 3+ , Nd 3+ , Er 3+ needs to be higher. If the concentration is lower than the above range, the luminescence is weak. If the concentration is higher than the above range, cross-relaxation will occur, resulting in weakened luminescence.

[0052] In the embodiment of the present invention, the mole fraction of Yb 3+ ions in the light-emitting layer is 30% - 70%, and / or the mole fraction of Tm 3+ ions is 0.2% - 1.5%, and / or the mole fraction of Er 3+ ions is 0.2% - 3%, and / or the mole fraction of Gd 3+ ions is 40% - 60%, or the mole fraction of Ce 3+ ions is 0.2% - 5%.

[0053] In the light-emitting layer, the concentration of the above Yb 3+ , Er 3+ , Tm 3+ , Gd 3+ , Ce 3+ is in the optimal range. If the concentration is lower than the above range, the luminescence is weak. If the concentration is higher than the above range, cross-relaxation will occur, resulting in weakened luminescence.

[0054] In the embodiment of the present invention, the mole fraction of Yb 3+ ions in the first energy trapping layer is 5% - 20%, and / or the mole fraction of Nd 3+ ions is 1% - 20%, or the mole fraction of Er 3+ ions is 1% - 25%.

[0055] In the first energy trapping layer, the concentration of the above Yb 3+ , Nd 3+ , Er 3+ is in the optimal range. If the concentration is lower than the above range, the luminescence is weak. If the concentration is higher than the above range, cross-relaxation will occur, resulting in weakened luminescence.

[0056] An embodiment of the second aspect of the present invention provides a method for preparing an ultraviolet / blue light-enhanced rare earth nanocomposite, comprising the following steps:

[0057] S1: Prepare rare earth nanomaterials;

[0058] S1.1: Dissolve rare earth salt A in a solvent to obtain precursor A; react precursor A under the conditions of a sodium source and a fluorine source to obtain a second energy capture layer, and the size of the second energy capture layer is 5 - 40 nm;

[0059] S1.2: Dissolve rare earth salt in a solvent to obtain precursor B; mix the second energy capture layer with precursor B, and in the presence of a sodium source and a fluorine source, perform shell coating on the second energy capture layer to obtain a core - shell structure nanocrystal containing the second energy capture layer and a luminescent layer; here, the shell layer is the luminescent layer, and the thickness of the luminescent layer is 2 - 10 nm;

[0060] S1.3: Dissolve rare earth salt C in a solvent to obtain precursor C; mix the core - shell structure nanocrystal with precursor C, and in the presence of a sodium source and a fluorine source, perform coating on the core - shell structure nanocrystal to obtain a rare earth nanomaterial with a core - shell - shell structure consisting of a second energy capture layer, a luminescent layer, and a first energy capture layer from the inside out; here, the outermost shell layer is the first energy capture layer, and the thickness of the first energy capture layer is 2 - 10 nm;

[0061] S2: Remove the surface ligands of the rare earth nanomaterial to obtain a ligand - free rare earth nanomaterial, add a picolinic acid solution to the solution of the ligand - free rare earth nanomaterial, and perform centrifugation to obtain a rare earth nanocomposite.

[0062] Preferably, disperse the oleic acid - coated rare earth nanomaterial in a hydrochloric acid solution, and perform ultrasonic treatment for 5 minutes to remove the surface ligands. Subsequently, collect the product by centrifugation, wash it with ethanol multiple times, and finally redisperse it in deionized water. Add the picolinic acid solution to the solution of the ligand - free nanoparticles. After the mixture is ultrasonically treated for 5 hours, the obtained clear solution is centrifuged to obtain a colloidal solid. The solid is washed with ethanol several times and then redispersed in ethanol.

[0063] Specifically, the preparation method of the core - shell - shell structure rare earth nanoparticles is as follows:

[0064] a. Precursor preparation:

[0065] Dissolve at least one rare earth salt of ytterbium salt (sensitizer), neodymium salt (sensitizer), gadolinium salt (luminescence center), thulium salt (luminescence center), yttrium salt (matrix material), lutetium salt (matrix material) in a mixed solvent of oleic acid and octadecene, and react at 140 - 170 o °C for 0.5 - 3 h to obtain a precursor;

[0066] The ytterbium salt is YbCl 3 、Yb(NO 3 ) 3 、Yb(CH 3CO 2 ) 3 、Yb(TFA) 3 、Yb(ACAC) 3 at least one of;

[0067] The neodymium salt is NdCl 3 、Nd(NO 3 ) 3 、Nd(CH 3 CO 2 ) 3 、Nd(TFA) 3 、Nd(ACAC) 3 at least one of;

[0068] The gadolinium salt is GdCl 3 、Gd(NO 3 ) 3 、Gd(CH 3 CO 2 ) 3 、Gd(TFA) 3 、Gd(ACAC) 3 at least one of;

[0069] The thulium salt is TmCl 3 、Tm(NO 3 ) 3 、Tm(CH 3 CO 2 ) 3 、Tm(TFA) 3 、Tm(ACAC) 3 at least one of;

[0070] The yttrium salt is YCl 3 、Y(NO 3 ) 3 、Y(CH 3 CO 2 ) 3 、Y(TFA) 3 、Y(ACAC) 3 at least one of;

[0071] The lutetium salt is LuCl 3 、Lu(NO 3 ) 3 、Lu(CH 3 CO 2 ) 3 、Lu(TFA) 3 、Lu(ACAC) 3 at least one of;

[0072] b. Preparation of the second energy capture layer by pyrolysis:

[0073] The precursor reacts in the presence of a sodium source and a fluorine source at 220 - 330 o °C for 0.5 - 3 h to obtain the second energy capture layer;

[0074] The sodium source is at least one of NaOH, NaF, and NaTFA; the fluorine source is at least one of NH 4 F, NaF, and rare earth trifluoroacetate complexes;

[0075] c. Preparation of the rare earth luminescent multi - layer core - shell structure material:

[0076] The material of the second energy capture layer is mixed with the precursor prepared in step a to obtain a reaction mixture. In the presence of a sodium source and a fluorine source, the reaction mixture is reacted to coat the up - conversion nanomaterial particles of the second energy capture layer with a shell, obtaining core - shell structure nanocrystals. Repeat step c to obtain a core - shell - shell structure, and then the reaction product of oil - soluble heterogeneous rare earth nanocrystals is washed and dissolved in cyclohexane to obtain a rare earth nanomaterial solution.

[0077] According to an embodiment of the third aspect of the present invention, there is also provided an application of the ultraviolet / blue - light enhanced rare earth nanocomposite in acrylate photopolymerization.

[0078] Preferably, the rare earth nanocomposite is used in acrylate photopolymerization for preparing 3D printing materials.

[0079] In an embodiment of the present invention, the preparation method of the 3D printing material includes the following steps:

[0080] (1) Synthesis of the 3D printing material

[0081] The rare earth nanocomposite (UCNPs) is mixed with a photocurable composition, ultrasonically treated, and then the solvent is evaporated by vacuum drying to form a liquid prepolymer; the prepolymer is the 3D printing material.

[0082] Preferably, the photocurable composition includes photoinitiator Irgacure 369, oligocarbonate methacrylate (OCM - 2), and polymethyl methacrylate (PMMA);

[0083] (2) Preparation of the 3D structural material

[0084] Near - infrared light can penetrate the 3D printing material, and the 3D printing material can initiate acrylate polymerization under the excitation of a near - infrared laser to cure and form a 3D structural material.

[0085] Under the excitation of a near-infrared semiconductor laser, the collimated laser beam is focused by an objective lens into a liquid prepolymer containing embedded UCNPs, enabling the near-infrared light to irradiate and penetrate the photocurable mixture, initiating acrylate polymerization. After the manufacturing is completed, the sample is developed in 2-propanol to remove the unpolymerized photocurable composition (photoinitiator, oligocarbonate methacrylate, polymethyl methacrylate), forming a 3D structural material.

[0086] In an embodiment of the present invention, the excitation power wavelength of the near-infrared light in step (2) is ~740 nm, ~793 nm, ~808 nm, ~980 nm, or ~1532 nm. Which excitation wavelength is selected as the excitation light source depends on the sensitizer. When Yb is selected as the sensitizer, a ~980 nm excitation light source is used; when Nd is selected as the sensitizer, ~740 nm, ~793 nm, or ~808 nm excitation light sources are used; when Er is selected as the sensitizer, ~808 nm or ~1532 nm excitation light sources are used; the excitation power density is 10~30Wcm -2 。

[0087] The following examples more specifically describe the content disclosed in this application, and these examples are only for illustrative purposes.

[0088] Example 1

[0089] This example provides a method for preparing an ultraviolet / blue light enhanced rare earth nanomaterial, wherein the rare earth nanoparticles with a core-shell-shell structure are NaYbF 4 @NaGdF 4 :Yb,Tm@NaLuF 4 :Yb, including the following steps:

[0090] Step A: Synthesize NaYbF 4 Naked core

[0091] First, an aqueous solution of 0.8 mmol of Yb(CH 3 CO 2 ) 3 ·xH 2 O, 10 mL of oleic acid, and 10 mL of 1-octadecene liquid are added to a 50 mL three-necked flask, heated to 150 °C, and stirred for 60 min to form a rare earth complex, obtaining a precursor A solution; then, the temperature is lowered to room temperature, 6.4 mmol of sodium oleate solid powder is added to the precursor A solution, and under vacuum conditions, the temperature is raised to 100 °C and stirred for 1 h; next, the above mixed solution is purged with nitrogen and 3.2 mmol of NH 3F solid powder, heat it to 160 °C and react for 1.5 h under nitrogen protection; finally, evacuate the above mixed solution for 10 min, then heat it to 320 °C under nitrogen protection and react for 30 min, then cool it to room temperature, wash it with anhydrous ethanol and cyclohexane, and disperse the obtained core nanoparticles in 4 mL of cyclohexane to obtain core nanoparticles NaYbF with a diameter of 20 nm. 4；

[0092] Step B: Synthesize NaYbF 4 @NaGdF 4 :Yb,Tm core-shell nanoparticles

[0093] According to the molar concentration ratio of Tm 3+ :Yb 3+ :Gd 3+ = 1:55:45, take the Tm(CH 3 CO 2 ) 3 ·xH 2 O, Yb(CH 3 CO 2 ) 3 ·xH 2 O, Gd(CH 3 CO 2 ) 3 ·xH 2 O aqueous solutions with a total of 0.4 mmol are added to a 50 mL three-necked flask, 5 mL of oleic acid and 5 mL of 1-octadecene liquid are added, heated to 150 °C, and stirred for 60 min to generate rare earth complexes to obtain precursor B solution; when the temperature drops to 80 °C, the core nanoparticle solution dispersed in 2 mL of cyclohexane obtained in the above step A is added to the precursor B solution, and stirred for 30 min to remove cyclohexane in the system. When the temperature drops to 50 °C, 5 mL of a methanol solution containing 1 mmol of NaOH and 1.36 mmol of NH 4 F is quickly added and stirred for 30 min to obtain a mixed solution; then the above mixed solution is heated to 100 °C, evacuated for 5 min and then filled with nitrogen for 1 min, repeated three times. After removing methanol and oxygen in the reaction system, the temperature is raised to 300 °C and reacted for 1.5 h under nitrogen protection. Then the obtained product is cooled to room temperature, and then washed with anhydrous ethanol and cyclohexane to obtain NaYbF 4 @NaGdF 4 : 49% Yb, 1% Tm core-shell nanomaterials are dispersed in 4 mL of cyclohexane, with a diameter of about 30 nm;

[0094] Step C: Synthesize NaYbF 4@NaGdF 4 :Yb,Tm@NaLuF 4 :Yb core-shell-shell nanoparticles

[0095] Take Lu at a molar concentration ratio of 3+ :Yb 3+ =90:10, and take 0.4 mmol of the aqueous solution of Lu(CH 3 CO 2 ) 3 ·xH 2 O, Yb(CH 3 CO 2 ) 3 ·xH 2 O in total and add it to a 50 mL three-necked flask. Add 3 mL of oleic acid and 7 mL of 1-octadecene liquid, heat to 150 °C, and stir for 30 - 60 min to form a rare earth complex and obtain precursor C solution. When the temperature drops to 80 °C, add the core-shell nanomaterial solution dispersed in 4 mL of cyclohexane obtained in step B to the precursor C solution, and stir for 30 min to remove cyclohexane from the system. When the temperature drops to 50 °C, quickly add 5 mL of a methanol solution containing 1 mmol of NaOH and 1.36 mmol of NH 4 F, and stir for 30 min to obtain a mixed solution; then heat the above mixed solution to 100 °C, evacuate for 5 min and then fill with nitrogen for 1 min, repeat three times. After removing methanol and oxygen from the reaction system, raise the temperature to 300 °C and react for 1.5 h under the protection of nitrogen. Subsequently, cool the obtained product to room temperature, and wash it with absolute ethanol and cyclohexane to obtain NaYbF 4 @NaGdF 4 :Yb,Tm@NaLuF 4 :Yb core-shell-shell upconversion nanoparticle luminescent material is dispersed in 4 mL of cyclohexane, and the material diameter is about 40 nm.

[0096] See Figures 1 to 3 , Figure 1 For the transmission electron microscope image of the NaYbF 4 @NaGdF 4 :Yb,Tm@NaLuF 4 :Yb nanoparticles in Example 1; where Figure a shows: NaYbF 4 nanocore; Figure b shows: NaYbF 4 @NaGdF 4 :Yb,Tm core-shell structure; Figure c shows: NaYbF 4 @NaGdF 4 :Yb,Tm@NaLuF4 : Yb core-shell-shell structure. The TEM images show that the synthesized nanomaterials have good morphology and uniform size, and the size of the materials increases with the growth of the shell layer.

[0097] Figure 2 For the NaYbF in Example 1 4 @NaGdF 4 : Yb, Tm@NaLuF 4 : High-angle annular dark field (HAADF) scanning transmission electron microscopy (STEM) image of the Yb nanomaterial. The image shows that the synthesized nanomaterial has a single-crystalline structure.

[0098] Figure 3 The luminescence spectrum of the multiphase energy-capturing rare-earth nanomaterial in Example 1. The emissions at 253, 273, 176, 279, and 311 nm are from Gd 3+ The emissions at 290, 345, 360, 450, 475, 511, and 650 nm are from Tm 3+ emissions.

[0099] Example 2

[0100] This example provides a method for preparing an ultraviolet / blue light-enhanced rare-earth nanocomposite, which includes the following steps:

[0101] Disperse the oleic acid-coated core-shell-shell upconversion nanoparticles prepared in Example 1 in a hydrochloric acid solution (1 mL; 2 M), and perform ultrasonic treatment for 5 minutes to remove the surface ligands. Subsequently, collect the product by centrifugation (16,500 rpm, 20 minutes), wash it with ethanol multiple times, and finally redisperse it in deionized water;

[0102] Add a pyridine-2-carboxylic acid solution (1.0 mL) to the ligand-free nanoparticle solution (1.0 mL, 0.1 mmol). After ultrasonic treatment of the mixture for 5 hours, the obtained clear solution is centrifuged to obtain a colloidal solid, which is washed with ethanol several times and then redispersed in ethanol (1.0 mL) to obtain a rare-earth nanocomposite with a pyridine-2-carboxylic acid layer on the surface.

[0103] See Figure 4 and Figure 5 , Figure 4 is the comparative luminescence intensity spectrum of the core-shell-shell rare-earth nanoparticles in Example 1 of the present invention and the rare-earth nanocomposite with a pyridine-2-carboxylic acid layer in Example 2; it can be seen from the figure that the luminescence intensity of the rare-earth nanocomposite with a pyridine-2-carboxylic acid layer in Example 2 is much greater than that of the core-shell-shell rare-earth nanoparticles without a pyridine-2-carboxylic acid layer in Example 1.

[0104] Figure 5 Schematic diagram of energy transfer of nanomaterials for unmodified and modified pyridine-2-carboxylic acid layers. The figure shows that the pyridine-2-carboxylic acid layer forms a coordination bond with the surface rare earth ions of the rare earth nanomaterials, protects the excitation energy, and promotes energy transfer.

[0105] Example 3

[0106] This example provides a preparation method of ultraviolet / blue light enhanced rare earth nanomaterials, wherein the core-shell-shell structure rare earth nanoparticles are NaYbF 4 :Nd@NaGdF 4 :Yb,Tm@NaYF 4 :Yb / Nd, and includes the following steps:

[0107] Step A: Synthesize NaYbF 4 :Nd bare core

[0108] First, an aqueous solution of 0.08 mmol of Yb(CH 3 CO 2 ) 3 ·xH 2 O and 0.0008 Nd(CH 3 CO 2 ) 3 ·xH 2 O, 10 mL of oleic acid and 10 mL of 1-octadecene liquid are added to a 50 mL three-necked flask, heated to 150 °C, and stirred for 60 min to generate a rare earth complex, obtaining a precursor A solution; then, the temperature is lowered to room temperature, 6.4 mmol of sodium oleate solid powder is added to the precursor A solution, and under vacuum conditions, the temperature is raised to 100 °C and stirred for 1 h; next, the above mixed solution is filled with nitrogen and 3.2 mmol of NH 3 F solid powder is added, the temperature is raised to 160 °C and reacted for 1.5 h under nitrogen protection; finally, the above mixed solution is evacuated for 10 min, and then the temperature is raised to 320 °C under nitrogen protection and reacted for 30 min, and then cooled to room temperature, washed with anhydrous ethanol and cyclohexane, and the obtained core nanoparticles are dispersed in 4 mL of cyclohexane, obtaining core nanoparticles NaYbF 4 :Nd;

[0109] Step B: Synthesize NaYbF 4 :Nd@NaGdF 4 :Yb,Tm core-shell nanoparticles

[0110] According to the molar concentration ratio of Tm 3+ :Yb 3+ :Gd 3+=0.5:55:45, take the Tm(CH with a fixed ratio 3 CO 2 ) 3 ·xH 2 O, Yb(CH 3 CO 2 ) 3 ·xH 2 O, Gd(CH 3 CO 2 ) 3 ·xH 2 O aqueous solution, a total of 0.4 mmol, was added to a 50 mL three-necked flask. 5 mL of oleic acid and 5 mL of 1-octadecene liquid were added, and the mixture was heated to 150 °C and stirred for 60 min to form a rare earth complex, obtaining a precursor B solution; when the temperature dropped to 80 °C, the core nanoparticle solution dispersed in 2 mL of cyclohexane obtained in the step A was added to the precursor B solution, and the mixture was stirred for 30 min to remove cyclohexane in the system. When the temperature dropped to 50 °C, 5 mL of a methanol solution containing 1 mmol of NaOH and 1.36 mmol of NH 4 F was quickly added and stirred for 30 min to obtain a mixed solution; then the above mixed solution was heated to 100 °C, evacuated for 5 min and then filled with nitrogen for 1 min, and this process was repeated three times. After removing methanol and oxygen in the reaction system, the temperature was raised to 300 °C, and the reaction was carried out for 1.5 h under the protection of nitrogen. Subsequently, the obtained product was cooled to room temperature, and then washed with absolute ethanol and cyclohexane to obtain NaYbF 4 :Nd @NaGdF 4 :49%Yb,1%Tm core-shell nanomaterials dispersed in 4 mL of cyclohexane, with a diameter of about 30 nm;

[0111] Step C: Synthesis of NaYbF 4 :Nd@NaGdF 4 :Yb,Tm@NaYF 4 :Yb / Nd core-shell-shell nanoparticles

[0112] According to the molar concentration ratio of Y 3+ :Yb 3+ :Nd = 90:10:1, take the Y(CH with a fixed ratio 3 CO 2 ) 3 ·xH 2 O, Yb(CH 3 CO 2 ) 3 ·xH 2 O and Nd(CH 3 CO 2 )3 ·xH 2 A total of 0.4 mmol of an aqueous solution of ·xH₂O was added to a 50 mL three-necked flask, 3 mL of oleic acid and 7 mL of 1-octadecene liquid were added, heated to 150 °C, and stirred for 30 - 60 min to form a rare earth complex, obtaining a precursor C solution for the shell. When the temperature dropped to 80 °C, the core-shell nanomaterial solution dispersed in 4 mL of cyclohexane obtained in the above step B was added to the precursor C solution, and stirred for 30 min to remove cyclohexane from the system. When the temperature dropped to 50 °C, 5 mL of a methanol solution containing 1 mmol of NaOH and 1.36 mmol of NH 4 F was quickly added and stirred for 30 min to obtain a mixed solution; then the above mixed solution was heated to 100 °C, evacuated for 5 min and then filled with nitrogen for 1 min, repeated three times. After removing methanol and oxygen from the reaction system, the temperature was raised to 300 °C, and the reaction was carried out for 1.5 h under the protection of nitrogen. Subsequently, the obtained product was cooled to room temperature, and then washed with absolute ethanol and cyclohexane to obtain NaYbF 4 :Nd@NaGdF 4 :Yb,Tm@NaYF 4 :Yb / Nd core-shell-shell upconversion nanoparticle luminescent materials dispersed in 4 mL of cyclohexane, and the diameter of the materials is about 40 nm.

[0113] Example 4

[0114] This example provides a preparation method of a UV / blue light enhanced rare earth nanomaterial, wherein the rare earth nanoparticles with a core-shell-shell structure are NaYbF 4 @NaGdF 4 :Yb,Tm@NaYF 4 :Yb, and it includes the following steps:

[0115] Step A: Synthesize NaYbF 4 naked core

[0116] First, 0.8 mmol of an aqueous solution of Yb(CH 3 CO 2 ) 3 ·xH 2 O, 10 mL of oleic acid and 10 mL of 1-octadecene liquid were added to a 50 mL three-necked flask, heated to 160 °C, and stirred for 60 min to form a rare earth complex, obtaining a precursor A solution; then, the temperature was lowered to room temperature, 6.4 mmol of sodium oleate solid powder was added to the precursor A solution, and under vacuum conditions, the temperature was raised to 100 °C and stirred for 1 h; next, the above mixed solution was filled with nitrogen and 3.2 mmol of NH 3F solid powder was heated to 150 °C and reacted for 1.0 h under nitrogen protection; finally, the above mixed solution was evacuated for 10 min, then the temperature was raised to 300 °C under nitrogen protection and reacted for 30 min, and then cooled to room temperature, washed with absolute ethanol and cyclohexane, and the obtained core nanoparticles were dispersed in 4 mL of cyclohexane, thus obtaining core nanoparticles NaYbF with a diameter of 20 nm. 4；

[0117] Step B: Synthesis of NaYbF 4 @NaGdF 4 :Yb,Tm core-shell nanoparticles

[0118] According to the molar concentration ratio of Tm 3+ :Yb 3+ :Gd 3+ =1:50:49, take the Tm(CH 3 CO 2 ) 3 ·xH 2 O, Yb(CH 3 CO 2 ) 3 ·xH 2 O, Gd(CH 3 CO 2 ) 3 ·xH 2 O aqueous solutions in total of 0.4 mmol were added into a 50 mL three-necked flask, 5 mL of oleic acid and 5 mL of 1-octadecene liquid were added, heated to 160 °C, and stirred for 60 min to form rare earth complexes, obtaining precursor B solution; when the temperature dropped to 80 °C, the core nanoparticle solution dispersed in 2 mL of cyclohexane obtained in the above step A was added to the precursor B solution, and stirred for 30 min to remove cyclohexane in the system. When the temperature dropped to 50 °C, 5 mL of methanol solution containing 1 mmol of NaOH and 1.36 mmol of NH 4 F was quickly added and stirred for 30 min to obtain a mixed solution; then the above mixed solution was heated to 100 °C, evacuated for 5 min and then filled with nitrogen for 1 min, repeated three times. After removing methanol and oxygen in the reaction system, the temperature was raised to 300 °C and reacted for 1.5 h under nitrogen protection. Subsequently, the obtained product was cooled to room temperature, and then washed with absolute ethanol and cyclohexane to obtain NaYbF 4 @NaGdF 4 :49%Yb,1%Tm core-shell nanomaterials were dispersed in 4 mL of cyclohexane, with a diameter of about 30 nm;

[0119] Step C: Synthesis of NaYbF 4@NaGdF 4 :Yb,Tm@NaYF 4 :Yb core-shell-shell nanoparticles

[0120] According to the molar concentration ratio of Y 3+ :Yb 3+ = 85:15, take a fixed ratio of Y(CH 3 CO 2 ) 3 ·xH 2 O, Yb(CH 3 CO 2 ) 3 ·xH 2 O aqueous solutions, a total of 0.4 mmol, are added to a 50 mL three-necked flask. 3 mL of oleic acid and 7 mL of 1-octadecene liquid are added, heated to 160 °C, and stirred for 30 - 60 min to form a rare earth complex, obtaining the precursor C solution of the shell. When the temperature drops to 80 °C, the core-shell nanomaterial solution dispersed in 4 mL of cyclohexane obtained in the step B is added to the precursor C solution, and stirred for 30 min to remove cyclohexane from the system. When the temperature drops to 50 °C, 5 mL of a methanol solution containing 1 mmol of NaOH and 1.36 mmol of NH 4 F is quickly added and stirred for 30 min to obtain a mixed solution; then the above mixed solution is heated to 100 °C, evacuated for 5 min and then filled with nitrogen for 1 min, repeated three times. After removing methanol and oxygen from the reaction system, the temperature is raised to 300 °C, and the reaction is carried out for 1.5 h under the protection of nitrogen. Subsequently, the obtained product is cooled to room temperature, and then washed with anhydrous ethanol and cyclohexane to obtain NaYbF 4 @NaGdF 4 :Yb,Tm@NaYF 4 :Yb core-shell-shell upconversion nanoparticle luminescent material is dispersed in 4 mL of cyclohexane, and the material diameter is about 40 nm.

[0121] Example 5

[0122] The application of the ultraviolet / blue light enhanced rare earth nanomaterial in this example is used for the 3D printing technology of ultraviolet light-induced photopolymerization reaction, and its steps are as follows:

[0123] (1) Synthesize liquid prepolymer

[0124] Equal portions of oligo (carbonate) methacrylate (OCM-2) and poly(methyl methacrylate) (PMMA) were used as a photocurable composition (PCC) with 1% photoinitiator Irgacure 369. The UCNPs material (rare earth nanocomposite) in ethanol was added to the photopolymerizable composition and sonicated for 10 minutes. After sonication, ethanol was evaporated by vacuum drying to obtain a liquid prepolymer. Here, PMMA was used to increase the viscosity of the mixture and prevent nanoparticle aggregation, and the final concentration of UCNPs was 15 mg / mL;

[0125] (2) Preparation of 3D printing material

[0126] A semiconductor CW laser with a near-infrared wavelength of 980 nm was used, and the power density of the laser was set to 15 Wcm −2 . The collimated laser beam was focused into the PCC volume containing the embedded UCNPs through an objective lens. The photopolymerization reaction was carried out in the local volume of the laser beam caustic where the maximum intensity was achieved. A galvanometer scanner provided fast and precise mirror positioning for laser beam deflection in the X-Y plane. The displacement of the voxel along the z coordinate was carried out by a micrometer stage. After completion of the fabrication, the sample was developed in 2-propanol to remove the unpolymerized PCC material, finally obtaining the 3D printed structural material. As Figure 6 shown.

[0127] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A UV / blue light enhanced rare earth nanocomposite material, characterized in that: The rare earth nanocomposite material comprises a rare earth nanomaterial and an organic coordination molecule layer arranged on the surface of the rare earth nanomaterial; the rare earth nanomaterial comprises a luminescent layer and a first energy capture layer arranged outside the luminescent layer, and an energy transfer channel is formed between the first energy capture layer and the luminescent layer; The rare earth nanomaterial further comprises a second energy capture layer disposed inside the light-emitting layer, and an energy transfer channel is formed between the second energy capture layer and the light-emitting layer; The main component of the organic coordination molecule layer is pyridine-2-carboxylic acid; The thickness of the second energy capture layer is 5-40 nm; the second energy capture layer is NaYbF4; The thickness of the light-emitting layer is 2-10 nm; the light-emitting layer is NaGdF4:Yb,Tm; Yb in the light-emitting layer 3+ The molar fraction of ions is 30% to 70%, Tm 3+ The molar fraction of ions is 0.2% to 1.5%; The thickness of the first energy capture layer is 2-10 nm; the first energy capture layer is NaLuF4:Yb; the Yb in the first energy capture layer 3+ The molar fraction of the ions is 5% to 20%.

2. Use of the ultraviolet / blue light enhanced rare earth nanocomposite material as claimed in claim 1 in acrylate photopolymerization.

3. The use according to claim 2, characterized in that: The rare earth nanocomposite material is used for preparing 3D printing materials.

4. The use according to claim 3, characterized in that: The preparation of the 3D printing material comprises the following steps: The rare earth nanocomposite material is mixed with a photocurable composition to form a liquid prepolymer; the prepolymer is the 3D printing material.

5. A method for preparing the ultraviolet / blue light enhanced rare earth nanocomposite material as claimed in claim 1, characterized in that: The following steps are involved: S1: Preparation of rare earth nanomaterials; S2: removing the ligands on the surface of the rare earth nanomaterial to obtain a ligand-free rare earth nanomaterial, adding a pyridine-2-carboxylic acid solution to the solution of the ligand-free rare earth nanomaterial, and centrifuging to obtain a rare earth nanocomposite material.

6. The method for preparing the ultraviolet / blue light enhanced rare earth nanocomposite material according to claim 5, characterized in that: Step S1 also includes the following contents: S1.1: dissolving rare earth salt A in a solvent to obtain a precursor A; reacting the precursor A under the conditions of a sodium source and a fluorine source to obtain a second energy capture layer; S1.2: dissolving a rare earth salt B in a solvent to obtain a precursor B; mixing the second energy capture layer with the precursor B, and encapsulating the second energy capture layer in the presence of a sodium source and a fluorine source to obtain a core-shell structured nanocrystal comprising the second energy capture layer and the light-emitting layer; S1.3: Dissolve the rare earth salt C in a solvent to obtain a precursor C; mix the core-shell structured nanocrystals with the precursor C, and wrap the core-shell structured nanocrystals in the presence of a sodium source and a fluorine source to obtain a rare earth nanomaterial with a core-shell-shell structure having, from the inside to the outside, a second energy capture layer, a light-emitting layer, and a first energy capture layer.

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