阅读说明：本技术 一种双模式荧光纳米颗粒复合材料、制备方法及应用 (Dual-mode fluorescent nanoparticle composite material, preparation method and application ) 是由 孙丽宁 谢耀 宋亚湃 蒋梦月 陈嘉博 于 2021-09-10 设计创作，主要内容包括：本发明公开了一种双模式荧光纳米颗粒复合材料、制备方法及应用,该复合材料由上转换发光纳米颗粒与EuSe半导体材料制成,其中的EuSe半导体材料均匀地包覆在上转换发光纳米颗粒表面,形成异质颗粒结构；其在两个不同波长激光光源激发下,分别发射两种不同颜色的荧光,且所发出的荧光均为肉眼清晰可见,可广泛应用于光学防伪、信息安全等领域用。本发明提供的复合材料形貌均一,分散性好,稳定性高；本发明提供的制备方法步骤简洁、易于控制、可重复性高；本发明材料通过组分与结构的协同作用,使所形成的防伪图案明亮、清晰、美感度高,可满足高档产品的防伪需求。(The invention discloses a dual-mode fluorescent nanoparticle composite material, a preparation method and application, wherein the composite material is prepared from up-conversion luminescent nanoparticles and a EuSe semiconductor material, wherein the EuSe semiconductor material is uniformly coated on the surfaces of the up-conversion luminescent nanoparticles to form a heterogeneous particle structure; the fluorescent light can emit two kinds of fluorescent light with different colors under the excitation of two laser light sources with different wavelengths, and the emitted fluorescent light can be clearly seen by naked eyes, so that the fluorescent light can be widely applied to the fields of optical anti-counterfeiting, information safety and the like. The composite material provided by the invention has the advantages of uniform appearance, good dispersibility and high stability; the preparation method provided by the invention has the advantages of simple steps, easy control and high repeatability; the material of the invention ensures that the formed anti-counterfeiting pattern is bright and clear and has high aesthetic feeling through the synergistic effect of the components and the structure, and can meet the anti-counterfeiting requirement of high-grade products.)

1. The dual-mode fluorescent nanoparticle composite material is characterized by being prepared from up-conversion luminescent nanoparticles and a EuSe semiconductor material, wherein the EuSe semiconductor material is uniformly coated on the surfaces of the up-conversion luminescent nanoparticles to form a heterogeneous particle structure.

2. The dual-mode fluorescent nanoparticle composite of claim 1, wherein the composite emits fluorescence that is clearly visible to the naked eye when excited by two laser sources with different wavelengths, forming dual-mode fluorescence of up-conversion luminescence and down-conversion luminescence, respectively.

3. A method for preparing the dual-mode fluorescent nanoparticle composite material of either of claims 1 or 2, comprising the steps of:

(1) weighing selenium powder with a set amount, adding the selenium powder into a single-mouth bottle, adding tri-n-octylphosphine according to a set proportion, and placing the single-mouth bottle into an ultrasonic oscillator for ultrasonic treatment until the solution in the bottle is clear and transparent to form a first dispersion liquid;

(2) weighing a europium source with a set amount, adding the europium source into a three-neck flask, sequentially adding a first dispersion liquid, oleylamine, oleic acid, octadecene and a cyclohexane dispersion liquid of upconversion luminescent nanoparticles with surface ligands of oleic acid according to a set proportion, heating to 280-300 ℃ under the protection of argon atmosphere, reacting for 3 hours, cooling to room temperature, and adding acetone; and precipitating the sample, ultrasonically washing the sample by using acetone, and centrifugally separating the sample to obtain the EuSe-coated rare earth up-conversion luminescent nano-particles, namely the dual-mode fluorescent nano-particle composite material.

4. The method for preparing dual mode fluorescent nanoparticle composite material according to claim 3, wherein the europium source in step (2) is one of europium nitrate, europium chloride, europium acetate, and hydrates thereof.

5. The preparation method of the dual-mode fluorescent nanoparticle composite material as claimed in claim 3, wherein the amount of tri-n-octylphosphine used in the step (2) is 2-3 mL relative to 1mmol of selenium powder.

6. The method for preparing the dual-mode fluorescent nanoparticle composite material according to claim 3, wherein the temperature during the ultrasonic treatment in the step (2) is 15 to 35 ℃, the ultrasonic time is 20 to 40 minutes, and the frequency of the ultrasonic wave is set to be 39 to 41 KHz.

7. The method for preparing a dual mode fluorescent nanoparticle composite material according to claim 3, wherein in step (2), the amount of the first dispersion liquid is 2 to 3mL, the amount of oleylamine is 3 to 5mL, the amount of oleic acid is 1 to 2mL, the amount of octadecene is 30 to 35mL, and the amount of upconversion nanoparticles with surface ligands of oleic acid is 1 to 2mmol relative to 1mmol of europium source.

8. The dual-mode fluorescence of claim 3A method for preparing a nanoparticle composite, characterized in that it further comprises improving EuSe-coated NaGdF using PVP₄The water-solubility of Yb, Tm nanoparticle composite material:

(3) dissolving the dual-mode fluorescent nanoparticle composite material synthesized in the step (2) in a cyclohexane solution to form a first dispersion liquid;

(4) weighing 0.5mmol NOBF₄Putting the mixture into a single-mouth bottle, adding 10mL of dichloromethane solution, putting the single-mouth bottle into an ultrasonic oscillator for ultrasonic treatment, wherein the temperature is controlled to be 25 ℃ during ultrasonic treatment, the ultrasonic time is 20 minutes, and the frequency of ultrasonic wave is 40 KHz. Performing ultrasonic treatment until the solution in the bottle is clear and transparent to form a second dispersion liquid;

(5) and (3) putting 5mL of the first dispersion liquid and 5mL of the second dispersion liquid into the same single-mouth bottle, and putting the single-mouth bottle into an ultrasonic oscillator for ultrasonic treatment, wherein the temperature is controlled to be 25 ℃ during ultrasonic treatment, the ultrasonic time is 20 minutes, and the frequency of ultrasonic waves is 40 KHz. Centrifuging at 15000 r/min to obtain solid precipitate, and dissolving the solid precipitate in 5-8 mL of deionized water to form a third dispersion;

(6) 0.1mmoL of polyvinylpyrrolidone is weighed and placed in a single-mouth bottle, 10mL of deionized water is added and stirred for 0.5 hour, and the temperature is controlled to be 30 ℃ while stirring. Forming a fourth dispersion;

(7) placing 2.5mL of the third dispersion and 2.5mL of the fourth dispersion in a single-mouth bottle for stirring; controlling the temperature to be 50 ℃ during stirring; the stirring time is controlled to be 24 hours, and the PVP modified dual-mode fluorescent nano-particle composite material is obtained.

9. Use of the bimodal fluorescent nanoparticle composite material as described in claim 1 or 2 as bimodal fluorescent filler for the preparation of solid or liquid products for up/down conversion bimodal optical anti-counterfeiting applications.

10. Use of the bimodal fluorescent nanoparticle composite material as claimed in claim 1 or 2 as bimodal fluorescent filler for the preparation of solid or liquid products for up/down conversion bimodal optical information storage or information security.

Technical Field

The invention relates to the technical field of nano materials and optical anti-counterfeiting, in particular to a dual-mode fluorescent nano particle composite material, a preparation method and application.

Background

Counterfeiting and counterfeiting of high-grade commodities are increasingly serious and long-standing global problems, are common in daily life, and cause cheating to consumers, so that normal commodity circulation and brand reputation are seriously influenced. Currently, counterfeit products produced by the illegal counterfeiting of packaging, trademarks, documents, and the like have penetrated many industries, including medicine, food, clothing, luxury goods, jewelry, software, paper currency, diploma, certificates, and the like. The counterfeit goods not only disturb the normal economic development order, but also damage the reputation of enterprises, and even form a great threat to the health of consumers. Therefore, the security materials and technologies are receiving more and more attention, and governments are also striving to develop advanced security technologies to protect important documents from being copied.

The application of fluorescent materials to anti-counterfeiting is one of the most effective technical means at present. With the progress of research, more and more optical materials, such as carbon quantum dots, metal organic frameworks, etc., are increasingly used for anti-counterfeiting. Chinese patent application CN201810836592.9 discloses a rare earth doped NaYF₄A preparation method and application of a/carbon quantum dot dual-mode fluorescent nano composite material are disclosed, wherein a cationic surfactant modified rare earth is doped with NaYF₄Mixing the water dispersion of the up-conversion nano particles with the carbon quantum dot solution, then adding alkali liquor, ethyl acetate and ethyl orthosilicate into the mixed solution, and doping NaYF in the rare earth by utilizing the sol-gel chemistry principle₄And coating a silicon dioxide shell layer on the surface of the particle, and encapsulating the carbon quantum dots in the shell layer to prepare the core-shell type nano composite material. The preparation method effectively avoids aggregation quenching of the carbon quantum dots, can be used for preparing ink, and applies the prepared composite material to the anti-counterfeiting field through ink-jet printing.

However, the preparation method provided by the technical scheme of the patent application has multiple steps, complex process and difficult control; the dual-mode fluorescent nano composite material provided by the invention has lower intensity under the excitation of near-infrared and ultraviolet dual-mode light sources, is not easy to directly identify by naked eyes, is dispersedly prepared into printing ink as fluorescent filler for outputting dim, lower definition and low aesthetic feeling of invisible fluorescent anti-counterfeiting patterns, can not meet the anti-counterfeiting requirements of high-grade products, and reduces the practicability.

Disclosure of Invention

Aiming at the problems that the preparation method is complex and the material performance is not enough in the prior art, and the formed pattern cannot meet the requirements of high-grade products on anti-counterfeiting patterns such as brightness, clearness and high aesthetic sensitivity, the invention aims to provide a dual-mode fluorescent nanoparticle composite material, a preparation method and application.

In order to achieve the purpose, the technical scheme provided by the invention is as follows:

the dual-mode fluorescent nanoparticle composite material is characterized by being prepared from up-conversion luminescent nanoparticles and a EuSe semiconductor material, wherein the EuSe semiconductor material is uniformly coated on the surfaces of the up-conversion luminescent nanoparticles to form a heterogeneous particle structure.

The composite material can emit fluorescence clearly visible to naked eyes under the excitation of two light sources with different wavelengths, and forms dual-mode fluorescence of up-conversion luminescence and down-conversion luminescence respectively.

A method of preparing the dual-mode fluorescent nanoparticle composite, comprising the steps of:

(1) weighing selenium powder with a set amount, adding the selenium powder into a single-mouth bottle, adding tri-n-octylphosphine according to a set proportion, and placing the single-mouth bottle into an ultrasonic oscillator for ultrasonic treatment until the solution in the bottle is clear and transparent to form a first dispersion liquid;

(2) weighing a europium source with a set amount, adding the europium source into a three-neck flask, sequentially adding a first dispersion liquid, oleylamine, oleic acid, octadecene and a cyclohexane dispersion liquid of upconversion luminescent nanoparticles with surface ligands of oleic acid according to a set proportion, heating to 280-300 ℃ under the protection of argon atmosphere, reacting for 3 hours, cooling to room temperature, and adding acetone; and precipitating the sample, ultrasonically washing the sample by using acetone, and centrifugally separating the sample to obtain the EuSe-coated rare earth up-conversion luminescent nano-particles, namely the dual-mode fluorescent nano-particle composite material.

The europium source in step (2) includes, but is not limited to, europium nitrate, europium chloride, europium acetate and hydrates thereof.

In the step (2), the dosage of the tri-n-octylphosphine is 2-3 mL relative to 1mmol of selenium powder.

The temperature during ultrasonic treatment in the step (2) is 15-35 ℃, the ultrasonic time is 20-40 minutes, and the frequency of ultrasonic waves is set to be 39-41 KHz.

In the step (2), the dosage of the first dispersion liquid is 2-3 mL, the dosage of oleylamine is 3-5 mL, the dosage of oleic acid is 1-2 mL, the dosage of octadecene is 30-35 mL, and the dosage of upconversion nanoparticles with surface ligands of oleic acid is 1-2 mmol relative to 1mmol of europium source.

The application of the dual-mode fluorescent nanoparticle composite material is characterized in that the dual-mode fluorescent nanoparticle composite material is used as a dual-mode fluorescent filler to prepare a solid or liquid product applied to up/down conversion dual-mode optical anti-counterfeiting.

The application of the dual-mode fluorescent nanoparticle composite material is characterized in that the dual-mode fluorescent nanoparticle composite material is used as a dual-mode fluorescent filler to prepare a solid or liquid product applied to up/down conversion dual-mode optical information storage or information safety.

Compared with the prior art, the invention has the beneficial effects that:

1. according to the dual-mode fluorescent nanoparticle composite material and the preparation method provided by the invention, the components, the structure and the preparation process of the material are synchronously improved, the europium selenide (EuSe) is specifically adopted to coat the up-conversion nanoparticles, and the fluorescent luminous intensity of the composite material is improved through the mutual synergistic effect of specific components and structures; compared with the existing optical anti-counterfeiting material, the material has the following outstanding advantages: (1) the raw materials are few in variety, the preparation process is simple and efficient, and the repeatability is high; (2) the material has stable structure, uniform shape and good monodispersity; (3) the material has the characteristic of up/down conversion dual-mode luminescence; (3) the structure and the components are mutually cooperated, so that the reduction of fluorescence intensity caused by cross relaxation among multiple lanthanide ion doping is avoided.

2. According to the preparation method of the dual-mode fluorescent nanoparticle composite material, the up-conversion nanoparticles are coated by the EuSe semiconductor to obtain the nanocomposite material with the up/down-conversion luminescence function, the method is simple in steps, convenient to operate, easy to control reaction conditions, high in repeatability, good in product consistency and dispersibility and easy to industrialize.

3. The dual-mode fluorescent nanoparticle composite material provided by the invention has the advantages of uniform size, good dispersibility, stable structure and performance, up/down conversion dual-mode luminescence and the like, wherein the rare earth up-conversion luminescent nanoparticles can emit up-conversion visible light under the irradiation of near infrared light, and the europium selenide semiconductor can emit macroscopic down-conversion blue light under the irradiation of ultraviolet light, so that the dual-mode fluorescent nanoparticle composite material can be widely applied to the fields of up/down conversion dual-mode optical anti-counterfeiting, information safety, storage and the like.

Drawings

FIG. 1 shows NaYF obtained in example 1 of the present invention₄Yb, Tm nanoparticles and EuSe-coated NaYF₄Transmission Electron Microscopy (TEM) photographs of composites of Yb, Tm nanoparticles;

FIG. 2 is a EuSe-coated NaYF obtained from example 2 of the present invention₄A fluorescence spectrum diagram of the composite material of Yb and Er nano particles under the excitation of a 980nm laser light source.

FIG. 3 is a EuSe-coated NaYF obtained from example 3 of the present invention₄A fluorescence spectrum diagram of the composite material of Yb and Ho nano particles under the excitation of a 365nm laser light source;

FIG. 4 is EuSe-coated NaGdF according to example 7 of the present invention₄Picture of anti-fake application of composite Yb, Tm nanometer particle material.

The present invention will be described in detail below with reference to the accompanying drawings and examples.

Detailed Description

Example 1:

the present example provides a bimodal fluorescent nanoparticle composite, specifically a EuSe packageCoated NaYF₄Yb, Tm upconversion luminescent nanoparticles.

The dual-mode fluorescent nanoparticle composite material provided in this example is composed of NaYF₄Yb, Tm up-conversion luminescent nanoparticles and a EuSe semiconductor material, wherein the EuSe semiconductor material is uniformly coated on the NaYF₄Yb, Tm nanoparticles to form a heterogeneous particle structure; the composite material can emit fluorescence clearly visible to naked eyes under the excitation of two laser light sources with different wavelengths, and forms dual-mode fluorescence of up-conversion luminescence and down-conversion luminescence respectively.

This EuSe-coated NaYF provided in this example₄The preparation method of the Yb, Tm up-conversion luminescence nanoparticle composite material comprises the following steps:

(1) weighing 1mmol of selenium powder, adding into a single-neck bottle, adding 2mL of tri-n-octylphosphonium, placing the single-neck bottle into an ultrasonic oscillator for ultrasonic treatment, wherein the temperature is controlled at 25 ℃, the ultrasonic time is 20 minutes, and the frequency of ultrasonic wave is 40 KHz. Sonicate until the solution in the vial is clear and transparent to form a first dispersion.

(2) Weighing 1mmol EuCl₃·6H₂Adding O into a three-neck flask, and then adding 2mL of first dispersion, 3mL of oleylamine, 1mL of oleic acid, 30mL of octadecene and 1mmol of NaYF with surface ligand of oleic acid₄A cyclohexane dispersion of Yb, Tm conversion luminescent nano particles, and reacting for 3 hours at a high temperature of 280-300 ℃ in an argon protective atmosphere. Cooling to room temperature, adding 40mL of acetone to precipitate the obtained composite material, placing the composite material in a high-speed centrifuge, setting the rotation speed of the centrifuge to 8000 rpm, and obtaining EuSe-coated NaYF by taking the lower-layer precipitate after the centrifugation is finished₄Yb, Tm nanoparticle composites.

The inventor group finds that in the research process of the conventional rare earth dual-mode luminescence anti-counterfeiting system, a plurality of rare earth elements with up-conversion and down-conversion characteristics are often uniformly mixed in the same material, and lanthanide elements often undergo cross relaxation to reduce the luminescence intensity, so that the formed anti-counterfeiting image and characters are unclear (low in definition) and are not easy to distinguish. The rare earth luminescent material adopted by the invention has excellent optical characteristics such as narrow-band emission peak, long fluorescence life, high stability and the like, but how to combine the rare earth luminescent material with lanthanide to avoid a cross relaxation field is a research focus of the invention and a technical problem to be solved. The dual-mode fluorescent nanoparticle composite material provided by the embodiment can emit fluorescence clearly visible to the naked eye under the excitation of two laser light sources with different wavelengths through the cooperation of material components and structures, and forms dual-mode fluorescence of up-conversion luminescence and down-conversion luminescence respectively, so that the technical problem is solved.

The invention is based on the defects that most of the existing rare earth luminescent systems for storing anti-counterfeiting information have single fluorescence mode, need specific expensive excitation light sources, have non-adjustable luminescent colors and the like, so that the problems of limited information storage and anti-counterfeiting capacity, cracking risk and the like are caused, and the research and development of new materials are started. The dual-mode luminescent material provided by the invention can fuse different fluorescent colors of up-conversion luminescence and down-conversion luminescence to the same luminescent platform, improve the technological content of anti-counterfeiting technology, establish a technical barrier to stop counterfeiting and fake behavior, and provide an efficient and convenient technical means for genuine product identification.

As shown in FIG. 1, (a) is NaYF₄Transmission electron micrographs of Yb, Tm nanoparticles, (b) EuSe-coated NaYF₄Transmission electron micrograph of composite of Yb, Tm nanoparticles shows that the morphology and properties of the composite obtained after EuSe semiconductor coating the nanoparticles are significantly changed into peanut (ellipsoid) nanoparticles.

The application of the dual-mode fluorescent nanoparticle composite material is used as a dual-mode fluorescent filler to prepare a solid or liquid product applied to up/down conversion dual-mode optical anti-counterfeiting, and can be particularly applied to manufacturing printing anti-counterfeiting ink, special anti-counterfeiting paper and the like.

Example 2:

the present example provides a dual-mode fluorescent nanoparticle composite material, a preparation method and applications thereof, which are substantially the same as those of example 1, except that the dual-mode fluorescent nanoparticle composite material, specifically, EuSe coated NaYF is used as the dual-mode fluorescent nanoparticle composite material₄Yb, Er upconversion luminescent nanoribbonsA composite of rice particles.

This example provides EuSe-coated NaYF₄The synthesis and preparation process of the Yb and Er nano-particle composite material comprises the following steps:

(1) weighing 1mmol of selenium powder, adding into a single-neck bottle, adding 2mL of tri-n-octylphosphonium, placing the single-neck bottle into an ultrasonic oscillator for ultrasonic treatment, wherein the temperature is controlled at 25 ℃, the ultrasonic time is 20 minutes, and the frequency of ultrasonic wave is 40 KHz. Sonicate until the solution in the vial is clear and transparent to form a first dispersion.

(2) Weighing 1mmol EuCl₃·6H₂Adding O into a three-neck flask, and then adding 2mL of first dispersion, 3mL of oleylamine, 1mL of oleic acid, 30mL of octadecene and 1mmol of NaYF with surface ligand of oleic acid₄Performing a high-temperature reaction on a cyclohexane dispersion of Yb and Er nano-particles for 3 hours at a temperature of 280-300 ℃ in an argon protective atmosphere. Cooling to room temperature, adding 40mL of acetone to precipitate the obtained composite material, placing the composite material in a high-speed centrifuge, setting the rotation speed of the centrifuge to 8000 rpm, and obtaining EuSe-coated NaYF by taking the lower-layer precipitate after the centrifugation is finished₄Yb and Er nano-particle composite material.

As shown in FIG. 2, the EuSe-coated NaYF₄Under the excitation of a 980nm laser light source, the Yb and Er nano-particle composite material mainly emits green light and red light, wherein the peak value of the green light is 545nm, and the peak value of the red light is 654 nm.

Example 3:

the present example provides a dual-mode fluorescent nanoparticle composite material, a preparation method and applications thereof, which are substantially the same as those of example 1, except that the dual-mode fluorescent nanoparticle composite material, specifically, EuSe coated NaYF is used as the dual-mode fluorescent nanoparticle composite material₄Yb, Ho nano particle composite material.

This example provides EuSe-coated NaYF₄The synthesis and preparation method of the Yb and Ho nano particle composite material comprises the following steps:

(1) weighing 1mmol of selenium powder, adding into a single-neck bottle, adding 2mL of tri-n-octylphosphonium, placing the single-neck bottle into an ultrasonic oscillator for ultrasonic treatment, wherein the temperature is controlled at 25 ℃, the ultrasonic time is 20 minutes, and the frequency of ultrasonic wave is 40 KHz. Sonicate until the solution in the vial is clear and transparent to form a first dispersion.

(2) Weighing 1mmol EuCl₃·6H₂Adding O into a three-neck flask, and then adding 2mL of first dispersion, 3mL of oleylamine, 1mL of oleic acid, 30mL of octadecene and 1mmol of NaYF with surface ligand of oleic acid₄The cyclohexane dispersion liquid of Yb and Ho nano particles is reacted for 3 hours at the high temperature of 280-300 ℃ in the argon protection atmosphere. Cooling to room temperature, adding 40mL of acetone to precipitate the obtained composite material, placing the composite material in a high-speed centrifuge, setting the rotating speed of the centrifuge to 8000 rpm, and taking the lower layer precipitate after the centrifugation is finished to obtain the EuSe-coated NaYF₄Yb, Ho nano particle composite material.

As shown in FIG. 3, the EuSe-coated NaYF₄The Yb and Ho nano particle composite material mainly emits blue light under the excitation of a 365nm light source, and the highest emission peak is positioned at 425 nm.

Example 4:

the present example provides a bimodal fluorescent nanoparticle composite, a method of making the same, and uses thereof, which are substantially the same as example 1, except that the bimodal fluorescent nanoparticle composite, specifically, EuSe coated NaErF₄Tm nanoparticle composites.

This example provides EuSe-coated NaErF₄The synthesis and preparation process of the Tm nanoparticle composite material comprises the following steps:

(1) weighing 1mmol of selenium powder, adding into a single-neck bottle, adding 2mL of tri-n-octylphosphonium, placing the single-neck bottle into an ultrasonic oscillator for ultrasonic treatment, wherein the temperature is controlled at 25 ℃, the ultrasonic time is 20 minutes, and the frequency of ultrasonic wave is 40 KHz. Sonicate until the solution in the vial is clear and transparent to form a first dispersion.

(2) Weighing 1mmol EuCl₃·6H₂Adding O into a three-neck flask, and adding 2mL of first dispersion, 3mL of oleylamine, 1mL of oleic acid, 30mL of octadecene and 1mmol of NaErF with surface ligand of oleic acid₄The cyclohexane dispersion liquid of the Tm nano particles reacts for 3 hours at a high temperature of 280-300 ℃ under the protection of argon. Cooling to room temperature, adding 40mL acetone to precipitate the composite material, placing the composite material in a high-speed centrifuge at 8000 rpm, and separatingCollecting the lower layer precipitate after cardiac arrest to obtain EuSe-coated NaErF₄Tm nanoparticle composites.

Example 5:

the present example provides a dual-mode fluorescent nanoparticle composite material, a preparation method and applications thereof, which are substantially the same as example 1, except that the dual-mode fluorescent nanoparticle composite material, specifically, EuSe-coated NaGdF₄Yb, Tm nanoparticle composites.

This example provides EuSe-coated NaGdF₄The synthesis and preparation process of the Yb, Tm nano particle composite material comprises the following steps:

(1) weighing 1mmol of selenium powder, adding into a single-neck bottle, adding 2mL of tri-n-octylphosphonium, placing the single-neck bottle into an ultrasonic oscillator for ultrasonic treatment, wherein the temperature is controlled at 25 ℃, the ultrasonic time is 20 minutes, and the frequency of ultrasonic wave is 40 KHz. Sonicate until the solution in the vial is clear and transparent to form a first dispersion.

(2) Weighing 1mmol EuCl₃·6H₂Adding O into a three-neck flask, and adding 2mL of the first dispersion, 3mL of oleylamine, 1mL of oleic acid, 30mL of octadecene and 1mmol of NaGdF with surface ligand of oleic acid₄The cyclohexane dispersion liquid of Yb and Tm nano particles reacts for 3 hours at the high temperature of 280-300 ℃ in the argon protection atmosphere. Cooling to room temperature, adding 40mL of acetone to precipitate the obtained composite material, placing the composite material in a high-speed centrifuge, setting the rotation speed of the centrifuge to 8000 rpm, and obtaining EuSe-coated NaGdF by taking the lower-layer precipitate after the centrifugation is finished₄Yb, Tm nanoparticle composites.

Example 6:

the present example provides a dual-mode fluorescent nanoparticle composite material, a method of making, and uses thereof, which are substantially the same as example 1, except that the dual-mode fluorescent nanoparticle composite material, in particular, improved EuSe-coated NaGdF using PVP₄Water solubility of Yb, Tm nanoparticle composites; the preparation method also comprises using PVP to improve EuSe coated NaGdF₄The water-solubility of Yb, Tm nanoparticle composite material:

(3) synthesizing the dual-mode fluorescent nanoparticles synthesized in the step (2)Composite material (EuSe-coated NaGdF in example 5)₄Yb, Tm nanoparticle composite material) dissolved in a cyclohexane solution to form a first dispersion;

(4) weighing 0.5mmol NOBF₄Putting the mixture into a single-mouth bottle, adding 10mL of dichloromethane solution, putting the single-mouth bottle into an ultrasonic oscillator for ultrasonic treatment, wherein the temperature is controlled to be 25 ℃ during ultrasonic treatment, the ultrasonic time is 20 minutes, and the frequency of ultrasonic wave is 40 KHz. Performing ultrasonic treatment until the solution in the bottle is clear and transparent to form a second dispersion liquid;

(5) and (3) putting 5mL of the first dispersion liquid and 5mL of the second dispersion liquid into the same single-mouth bottle, and putting the single-mouth bottle into an ultrasonic oscillator for ultrasonic treatment, wherein the temperature is controlled to be 25 ℃ during ultrasonic treatment, the ultrasonic time is 20 minutes, and the frequency of ultrasonic waves is 40 KHz. Centrifuging at 15000 r/min to obtain solid precipitate, and dissolving the solid precipitate in 5-8 mL of deionized water to form a third dispersion;

(6) 0.1mmoL of polyvinylpyrrolidone is weighed and placed in a single-mouth bottle, 10mL of deionized water is added and stirred for 0.5 hour, and the temperature is controlled to be 30 ℃ while stirring. Forming a fourth dispersion;

(7) placing 2.5mL of the third dispersion and 2.5mL of the fourth dispersion in a single-mouth bottle for stirring; controlling the temperature to be 50 ℃ during stirring; the stirring time is controlled to be 24 hours, and the PVP modified dual-mode fluorescent nanoparticle composite material (EuSe coated NaGdF) is obtained₄Yb, Tm nanoparticle composites).

Likewise, using this procedure, the water solubility of the dual-mode fluorescent nanoparticle composites prepared in examples 1-4 can also be increased.

Example 7:

the embodiment provides a specific application of a dual-mode fluorescent nanoparticle composite material in the field of anti-counterfeiting, and the dual-mode fluorescent nanoparticle composite material is used as a dual-mode fluorescent filler to prepare a solid or liquid product applied to up/down conversion dual-mode optical anti-counterfeiting.

Specifically, this example provides coating NaGdF with EuSe₄The process of anti-fake application of Yb, Tm nanometer particle composite material includes the following steps:

(1) the EuSe synthesized as described in example 5 was coated with NaGdF₄A composite of Yb, Tm nanoparticles dispersed in a cyclohexane solution to form a first dispersion (which may be further formulated with other components into a printing ink);

(2) the synthesis described in example 6 was carried out using EuSe-coated NaGdF modified with PVP₄A Yb, Tm nanoparticle composite forming a second dispersion;

(3) respectively and uniformly coating the first dispersion liquid and the second dispersion liquid on different parts of the non-fluorescent paper, then placing the non-fluorescent paper in a drying oven for drying for 10 minutes, controlling the temperature of the drying oven to be 60 ℃, drying the non-fluorescent paper, and then carrying out fluorescence test.

As shown in FIG. 4, (a) is a coated EuSe-coated NaGdF₄A photograph of a non-fluorescent paper of a Yb, Tm nanoparticle composite material under natural light; (b) the EuSe-coated NaGdF is coated under 365nm ultraviolet lamp₄A photograph of a non-fluorescent paper of a Yb, Tm nanoparticle composite material, confirming that the composite material emits blue light under 365nm ultraviolet lamp irradiation; (c) the EuSe-coated NaGdF is coated under 980nm near infrared light₄A photograph of a non-fluorescent paper of a Yb, Tm nanoparticle composite material demonstrating that the composite material emits violet light under 980nm near infrared radiation;

in other embodiments, the dual-mode fluorescent nanoparticle composite material is used as an anti-counterfeiting filler, and can be further prepared into liquid anti-counterfeiting products such as printing ink, water-based paint and the like together with other components, and the solid anti-counterfeiting products are formed after drying.

Example 8:

the application of the dual-mode fluorescent nanoparticle composite material provided by the embodiment is used as a dual-mode fluorescent filler to prepare a solid or liquid product applied to up/down conversion dual-mode optical information storage or information security. Specifically, EuSe-coated NaGdF prepared in example 6, with PVP to improve water solubility₄Yb and Tm nano particle composite material is used as an anti-counterfeiting filler and added into aqueous papermaking slurry, a non-uniform and natural anti-counterfeiting pattern is formed in the papermaking forming process, and anti-counterfeiting special paper is obtained after drying.

The key point of the invention is that a layer of europium selenide semiconductor is coated on the surface of the rare earth upconversion luminescent nano particle, and the two layers of europium selenide semiconductors are cooperated, wherein the rare earth upconversion luminescent nano particle can emit upconversion visible light under the irradiation of near infrared light, and the europium selenide semiconductor can emit macroscopic down-conversion blue light under the irradiation of ultraviolet light. The europium selenide coated rare earth up-conversion nano particle composite material provided by the invention can be used in the fields of up/down conversion dual-mode optical anti-counterfeiting, information safety, storage and the like. The preparation method provided by the invention has the advantages of simple steps, easiness in control, high repeatability and the like.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any way. Those skilled in the art can make many possible variations or modifications to the disclosed solution, using the methods and techniques disclosed above, to equivalents thereof without departing from the scope of the invention. Therefore, all equivalent modifications made according to the structure, structure and principle of the present invention should be covered within the protection scope of the present invention without departing from the contents of the technical scheme of the present invention.