Zirconia sol based on electric field regulation of refractive index, preparation method and application thereof

Abstract

The application discloses a preparation method of zirconia sol based on electric field regulation and control of refractive index, and belongs to the technical field of nanometer materials. A zirconium source and a chelating agent are added into an organic solvent to prepare a precursor solution; an alkali source is added into the organic solvent to prepare a pH regulator; the precursor solution and the pH regulator are added dropwise into the organic solvent, and the organic solvent is heated in an oil bath to obtain zirconia sol; an azobenzene compound is dissolved in the organic solvent to prepare an azobenzene modifier, the azobenzene modifier is added into the zirconia sol, and stirring is conducted to obtain azobenzene-modified zirconia sol. The application regulates and controls the particle size of the zirconia sol by adding the pH regulator and the chelating agent, thereby regulating and controlling the refractive index, and the azobenzene modification is used to endow the zirconia sol with electric field response characteristics, so that the electric field can finely and reversibly regulate and control the refractive index of the sol, and the dynamic regulation and control of the refractive index by the electric field can meet the demand of complex scenes.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of nanomaterials, and particularly relates to a zirconia sol based on electric field regulation of refractive index, a preparation method and application thereof. BACKGROUND

[0002] In the field of modern optics and optoelectronics, the regulation of material refractive index is always a research focus. With the rapid development of information technology, the demand for materials with dynamically adjustable refractive index is increasingly urgent in many fields such as optical communication, optical storage, display technology and optical sensing.

[0003] Traditional refractive index regulation methods such as thermo-optic effect and acousto-optic effect have many drawbacks. The thermo-optic effect requires heating or cooling of the material to change the refractive index, which is slow in response and high in energy consumption. Moreover, in some temperature-sensitive systems, it is easy to cause problems in thermal stability. The acousto-optic effect cannot be separated from complex acousto-optic modulators, and it requires high driving power, resulting in high cost and large size of the equipment.

[0004] Zirconia sol has been fully and deeply explored in the field of optics and has achieved remarkable results in practical applications. Its optical performance is excellent, and it has unique refractive index characteristics, which can meet the general needs of optical devices. However, the traditional preparation process of zirconia sol has obvious limitations and cannot achieve adjustable particle size. The controllability of particle size plays an important role in the regulation of refractive index. In this method system, the particle size of zirconia sol is well controllable, which can effectively adapt to various types of optical application scenarios and meet the diversified needs of optical applications.

[0005] By regulating zirconia sol, it can better match the design specifications of various types of optical devices, and effectively fill the gap in flexibility of traditional refractive index regulation methods.

[0006] Azobenzene compounds are a class of organic molecules with unique photoisomerization properties. Under the action of different wavelengths of light or electric field, the molecular structure can reversibly convert between cis and trans. This isomerization phenomenon will cause significant changes in the physical and chemical properties of the molecule such as dipole moment, polarizability and intermolecular interaction. Based on the electric field regulation of refractive index of azobenzene modified nanoparticles, combined with the controllable particle size of zirconia, the sensitivity of refractive index regulation can be further improved, which has a bright prospect in the development of new high-performance optical devices such as intelligent optical switches, tunable optical filters, dynamic focusing lenses, and promotes the evolution of optical materials and optoelectronic devices towards miniaturization, intelligence and multifunctionality.

[0007] For example, the application with publication number CN115594946A discloses a composite material for LED packaging and a preparation method thereof. The nano titanium dioxide is first modified by mercapto modification, then the vinyl silicone oil is grafted on the surface of the nano titanium dioxide through click reaction, the modified titanium dioxide nanoparticles capable of dispersing in various organic solvents and having high dispersibility in epoxy resin are obtained through two-step modification of gamma-mercaptopropyl trimethoxysilane and vinyl silicone oil, the transmittance of the packaging material can reach more than 90%, then the adamantyl with high refractive group is grafted on the surface of the nano zirconium oxide to improve the refractive index of the packaging material, and the active group is introduced on the surface of the nano zirconium oxide by modifying the nano zirconium oxide, then the crosslinking reaction occurs between the modified nano titanium dioxide, the modified nano zirconium oxide and the epoxy resin, the crosslinking density of the packaging material is improved, and the hardness of the packaging material is improved. However, the preparation process of the method is complicated, the energy loss in the material preparation process is heavy, the refractive index of the material cannot be dynamically adjusted in the application process, and the demand of complex scenes cannot be met. SUMMARY

[0008] In view of the problems of the prior art, the present application provides a zirconia sol based on electric field regulation of refractive index, a preparation method and application thereof. The composite system of azobenzene and zirconia nanoparticles with adjustable particle size in the preparation process is constructed by using fusion technology. Under the action of an electric field, azobenzene molecules undergo isomerization transformation, which changes the micro electromagnetic environment around the zirconia nanoparticles, thereby dynamically regulating the refractive index of the system to meet specific technical requirements.

[0009] A preparation method of a zirconia sol based on electric field regulation of refractive index, comprising the following steps:

[0010] (1) adding a zirconium source and a chelating agent into an organic solvent to prepare a precursor solution;

[0011] (2) adding an alkali source into an organic solvent to prepare a pH adjuster;

[0012] (3) simultaneously adding the precursor solution prepared in step (1) and the pH adjuster prepared in step (2) into the organic solvent, and heating by oil bath to obtain a zirconia sol;

[0013] (4) dissolving an azobenzene compound in an organic solvent to prepare an azobenzene modifier, and adding the azobenzene modifier into the zirconia sol prepared in step (3) and stirring to obtain an azobenzene-modified zirconia sol.

[0014] The present application is based on the photoisomerization property of azobenzene. When irradiated by light of different wavelengths or subjected to electric field, the molecular structure of azobenzene compound can be reversibly converted between cis and trans. This isomerization phenomenon can cause significant changes in the physical and chemical properties of the molecule, such as dipole moment, polarizability and intermolecular interaction. The characteristics of zirconia nanoparticles in regulating refractive index are combined with each other. By modifying the surface of zirconia nanoparticles with azobenzene molecules, the dynamic regulation of the refractive index of the composite material is achieved by electric field induction.

[0015] Preferably, the zirconium source is zirconium oxychloride or zirconyl nitrate.

[0016] The chelating agent is sodium citrate, ethylenediaminetetraacetic acid, triethanolamine or ammonium citrate.

[0017] The appropriate zirconium source and chelating agent are selected. The zirconium source provides zirconium ions for the hydrolysis reaction, and the chelating agent plays a role in chelating zirconium ions. In this way, the hydrolysis rate of the zirconium source is regulated, and the slow hydrolysis of the zirconium source avoids the production of precipitates due to rapid reaction and inhibits particle agglomeration. The complex formed by the chelating agent and the zirconium ion slowly releases zirconium ions, making the nucleation and growth process of the zirconia sol more uniform.

[0018] Further preferably, the molar percentage of the zirconium source in the precursor solution is 1% to 3%, and the molar percentage of the chelating agent in the precursor solution is 0.05% to 1%.

[0019] The precursor solution prepared by selecting the zirconium source and chelating agent within the above range can form a uniform precursor solution, allowing the zirconium source to be fully chelated with the chelating agent. The zirconium source within this concentration range can accelerate the reaction rate, and the prepared zirconia nanoparticles have a smaller particle size.

[0020] Preferably, the alkali source is sodium acetate or sodium carbonate.

[0021] The appropriate alkali source is selected to regulate the pH, and the particle size of the zirconia sol is regulated by changing the pH, thereby preparing zirconia nanoparticles of different particle sizes to dynamically regulate the refractive index.

[0022] Further preferably, the molar percentage of the alkali source in the pH regulator is 0.05% to 1%.

[0023] Preferably, the organic solvent is ethylene glycol or propylene glycol.

[0024] The appropriate organic solvent is selected to ensure complete dissolution of the solute, thereby ensuring uniformity of the solution throughout the preparation process.

[0025] Preferably, a peristaltic pump is used for dropping, and the rate of the peristaltic pump is 0.2 rpm to 0.5 rpm. After dropping, the pH is 8.5 to 8.7.

[0026] By adjusting the peristaltic pump rate, the reaction rate is controlled, which is conducive to the uniform growth of the crystal grains. The peristaltic pump rate in the above range can make the mixing rate of the precursor solution and the pH adjuster appropriate, adjust the pH to be in a weak alkaline state, and then regulate the sol particle size, so as to form a zirconia sol with uniform crystal grain size and appropriate particle size.

[0027] Preferably, the volume ratio of the precursor solution to the pH adjuster in step (3) is 0.9-1.1:1; and the volume ratio of the organic solvent to the pH adjuster in step (3) is 4.5-5.5:1.

[0028] During the peristaltic pump dripping process, the volumes of the organic solvent, the precursor solution and the pH adjuster are controlled according to the actual reaction conditions, so that the nucleation and growth process of the nanoparticles is more uniform, and precipitation is avoided.

[0029] Preferably, the temperature of the oil bath heating is at least 140℃, and the time is at least 2h.

[0030] By adjusting the reaction temperature and the reaction time, the formation of the zirconia sol can be promoted, and by regulating these two variables, zirconia sols with different particle sizes can be prepared, so as to effectively adjust the refractive index within a certain range.

[0031] Preferably, the azobenzene compound is 4-aminoazobenzene or 2-(4-hydroxyphenylazo)benzoic acid.

[0032] During the reaction process, there are differences in the interaction mechanisms of different azobenzene derivatives with zirconia nanoparticles. When 4-aminoazobenzene is selected, the amino group in the molecule will produce electrostatic attraction with the hydroxyl group on the surface of the zirconia nanoparticles, thereby promoting the attachment of 4-aminoazobenzene molecules to the surface of the zirconia nanoparticles. When 2-(4-hydroxyphenylazo)benzoic acid is selected, the molecule will gradually migrate to the surface of the zirconia nanoparticles and interact. In this process, the carboxyl group in the 2-(4-hydroxyphenylazo)benzoic acid molecule will form a -COO-Zr-OH2 + structure with the hydroxyl group (-OH) on the surface of the zirconia nanoparticles, thereby forming chemical adsorption; at the same time, there is also a certain degree of physical adsorption, and the two adsorption modes act together to make the 2-(4-hydroxyphenylazo)benzoic acid molecules firmly attached to the surface of the zirconia nanoparticles.

[0033] Further, the molar percentage of the azobenzene compound in the azobenzene modifier is 0.0-0.1%.

[0034] Preferably, the stirring speed is 100-500rpm, the stirring temperature is 30-60℃, and the stirring time is 2h-6h.

[0035] Stirring is carried out in the above parameter range, promoting the chemical bonding or physical adsorption between the azobenzene compound and the active sites on the surface of the zirconia sol, and then realizing the firm modification effect, thereby enhancing the response sensitivity of the zirconia nanoparticles to the external electric field.

[0036] The application further provides the zirconia sol based on the electric field regulated refractive index prepared by the preparation method.

[0037] Preferably, the refractive index of the zirconia sol based on the electric field regulated refractive index is 1.55-1.60.

[0038] The application further provides the application of the zirconia sol based on the electric field regulated refractive index prepared by the preparation method in intelligent optical sensors, tunable optical filters and dynamic focusing lenses.

[0039] Compared with the prior art, the application has the beneficial effects that:

[0040] (1) The particle size of the zirconia sol is regulated by the pH regulator and the chelating agent, and then the refractive index is regulated.

[0041] (2) After the prepared zirconia sol is modified by the azobenzene group, the zirconia sol is endowed with the electric field response characteristics, realizing the delicate and reversible regulation of the electric field on the refractive index of the sol, and the complex scene can be effectively coped with.

[0042] (3) The zirconia sol is prepared by the oil bath method, the preparation process is simple, the reaction time is short, the required temperature is low, and the reaction energy consumption is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 It is the physical map of the azobenzene-modified zirconia sol prepared in Example 1;

[0044] Figure 2 It is the particle size distribution map of the azobenzene-modified zirconia sol prepared in Example 1;

[0045] Figure 3 It is the scanning electron microscope (SEM) map of the azobenzene-modified zirconia sol prepared in Example 1. DETAILED DESCRIPTION

[0046] The specific implementation of the application is further described in detail in combination with the drawings and examples, but the implementation and protection of the application are not limited thereto. It should be pointed out that, if the following processes are not particularly described in detail, they can be realized or understood by the person skilled in the art according to the prior art.

[0047] Example 1

[0048] A preparation method of zirconia sol based on electric field regulation of refractive index, comprising the following steps:

[0049] First, prepare ethylene glycol as a solvent for the reaction, and place it in three separate containers.

[0050] In the first container, add 10 mL of ethylene glycol, accurately weigh a certain amount of zirconium oxychloride and sodium citrate into the ethylene glycol with a balance, and prepare a precursor solution, wherein the concentration of zirconium oxychloride is 1.5 mol / L, and the concentration of sodium citrate is 0.1 mol / L.

[0051] In the second container, add 10 mL of ethylene glycol, accurately weigh a certain amount of sodium acetate into it with a balance, stir uniformly after adding, and prepare a 0.1 mol / L sodium acetate solution as a pH regulator.

[0052] Finally, in the third container, add 50 mL of ethylene glycol, and at the same time, use a peristaltic pump to add the precursor solution and the sodium acetate solution at a speed of 0.2 rpm, the concentration of the precursor solution is 1.5 mol / L, the concentration of the sodium acetate solution is 0.1 mol / L, the pH after dripping is 8.7, and it is placed in a 140℃ high-temperature oil bath for 2h to obtain a clear zirconia sol.

[0053] Prepare a 4-aminoazobenzene-ethylene glycol modifier solution with a mass fraction of 1% by dissolving 4-aminoazobenzene in ethylene glycol; take 30 mL of 4-aminoazobenzene-ethylene glycol modifier solution with a mass fraction of 1% and slowly add it to 20 mL of zirconia sol. Place the mixed solution in a 60℃ magnetic stirring constant-temperature water bath, stir at a stirring speed of 500 rpm, and react for 6h to obtain azobenzene-modified zirconia sol.

[0054] During the reaction, the amino group in the 4-aminoazobenzene molecule forms electrostatic attraction with the hydroxyl group on the surface of the zirconia nanoparticle, so that the azobenzene molecule adheres to the surface of the zirconia nanoparticle, and the azobenzene-modified zirconia sol is obtained.

[0055] From the results of Figure 1 It can be seen that the prepared azobenzene-modified zirconia sol presents a uniform and transparent dispersion phase state, has good dispersion uniformity, Figure 2 It can be seen that the prepared zirconia sol has a particle size of about 50 nm.

[0056] Example 2

[0057] A preparation method of zirconia sol based on electric field regulation of refractive index, comprising the following steps:

[0058] First, prepare propylene glycol as a solvent for the reaction, and place it in three separate containers.

[0059] In the first container, 10 mL of propylene glycol was added, and a certain amount of zirconyl nitrate and sodium citrate was accurately weighed and added into the propylene glycol by a balance to prepare a precursor solution, wherein the concentration of the zirconyl nitrate was 2 mol / L, and the concentration of the sodium citrate was 0.1 mol / L.

[0060] In the second container, 10 mL of propylene glycol was added, and a certain amount of sodium acetate was accurately weighed and added into the propylene glycol by a balance to prepare a 0.15 mol / L sodium acetate solution as a pH regulator.

[0061] Finally, 50 mL of propylene glycol was added into the third container, and the precursor solution and the sodium acetate solution were added dropwise at a speed of 0.3 rpm by a peristaltic pump, the concentration of the precursor solution was 1.5 mol / L, the concentration of the sodium acetate solution was 0.1 mol / L, the pH after the dropwise addition was 8.7, and the mixture was placed in a 140℃ high-temperature oil bath to react for 2 h to obtain a clear zirconia sol.

[0062] A 4-aminoazobenzene-propylene glycol modifier solution with a mass fraction of 1% was prepared by dissolving 4-aminoazobenzene in propylene glycol; 30 mL of the 4-aminoazobenzene-propylene glycol modifier solution with a mass fraction of 1% was slowly added to 20 mL of the zirconia sol. The mixed solution was placed in a 60℃ magnetic stirring constant-temperature water bath, and stirred at a stirring speed of 500 rpm for 4 h to obtain an azobenzene-modified zirconia sol.

[0063] During the reaction, the amino group in the 4-aminoazobenzene molecule formed electrostatic attraction with the hydroxyl group on the surface of the zirconia nanoparticles, so that the azobenzene molecules were attached to the surface of the zirconia nanoparticles to obtain the azobenzene-modified zirconia sol.

[0064] Example 3

[0065] A preparation method of a zirconia sol based on electric field regulation of refractive index, comprising the following steps:

[0066] First, ethylene glycol was prepared as a solvent for the reaction, and was placed in three independent containers.

[0067] In the first container, 10 mL of ethylene glycol was added, and a certain amount of zirconyl chloride and sodium citrate was accurately weighed and added into the ethylene glycol by a balance to prepare a precursor solution, wherein the concentration of the zirconyl chloride was 2 mol / L, and the concentration of the sodium citrate was 0.1 mol / L.

[0068] In the second container, 10 mL of ethylene glycol was added, and a certain amount of sodium acetate was accurately weighed and added into the ethylene glycol by a balance to prepare a 0.1 mol / L sodium acetate solution as a pH regulator.

[0069] Finally, 50 mL of ethylene glycol was added in the third container, while the precursor solution and sodium acetate solution were added dropwise at a speed of 0.4 rpm by using a peristaltic pump, the concentration of the precursor solution was 1.5 mol / L, the concentration of the sodium acetate solution was 0.1 mol / L, the pH after dropping was 8.7, and the mixture was placed in a high-temperature oil bath at 140°C for 2 hours to obtain a clear zirconia sol.

[0070] A 2-(4-hydroxyphenylazo)benzoic acid-ethylene glycol modifier solution with a mass fraction of 1% was prepared by dissolving 2-(4-hydroxyphenylazo)benzoic acid in ethylene glycol; 30 mL of the 2-(4-hydroxyphenylazo)benzoic acid-ethylene glycol modifier solution with a mass fraction of 1% was slowly added to 20 mL of the zirconia sol. The mixed solution was placed in a 60°C magnetic stirring constant-temperature water bath and stirred at a stirring speed of 500 rpm for 4 hours to obtain an azobenzene-modified zirconia sol.

[0071] During the reaction, the 2-(4-hydroxyphenylazo)benzoic acid molecules gradually migrated to the surface of the zirconia nanoparticles and reacted. The carboxyl groups in the 2-(4-hydroxyphenylazo)benzoic acid molecules and the hydroxyl groups (-OH) on the surface of the zirconia nanoparticles may form -COO-Zr-OH2 + Such a structure forms chemical adsorption and also has a part of physical adsorption, so that the azobenzene molecules are firmly attached to the surface of the zirconia nanoparticles.

[0072] Example 4

[0073] A preparation method of a zirconia sol based on electric field regulation of refractive index, comprising the following steps:

[0074] First, prepare propylene glycol as a reaction solvent and place it in three separate containers.

[0075] In the first container, add 10 mL of propylene glycol, accurately weigh a certain amount of zirconyl nitrate and sodium citrate into the propylene glycol, and prepare a precursor solution, wherein the concentration of zirconyl nitrate is 1.5 mol / L and the concentration of sodium citrate is 0.1 mol / L.

[0076] In the second container, add 10 mL of propylene glycol, accurately weigh a certain amount of sodium acetate into the propylene glycol, and stir until uniform to prepare a 0.15 mol / L sodium acetate solution as a pH regulator.

[0077] Finally, the third container was added with 50 mL of propylene glycol, while the precursor solution and sodium acetate solution were added dropwise at a speed of 0.5 rpm by using a peristaltic pump, the concentration of the precursor solution was 1.5 mol / L, the concentration of the sodium acetate solution was 0.1 mol / L, the pH after dropping was 8.7, and the mixture was placed in a high-temperature oil bath at 140°C for 2 hours to obtain a clear nano-zirconium oxide sol.

[0078] A 4-aminoazobenzene-propylene glycol modifier solution with a mass fraction of 1% was prepared by dissolving 4-aminoazobenzene in propylene glycol; 30 mL of the 4-aminoazobenzene-propylene glycol modifier solution with a mass fraction of 1% was slowly added to 20 mL of the zirconium oxide sol. The mixed solution was placed in a 60°C magnetic stirring constant-temperature water bath and stirred at a stirring speed of 500 rpm for 4 hours to obtain the azobenzene-modified zirconium oxide sol.

[0079] During the reaction, the amino group in the 4-aminoazobenzene molecule was electrostatically attracted to the hydroxyl group on the surface of the zirconium oxide nanoparticles, so that the azobenzene molecules were attached to the surface of the zirconium oxide nanoparticles to obtain the azobenzene-modified zirconium oxide sol.

[0080] Comparative Example 1

[0081] First, ethylene glycol was prepared as a solvent for the reaction and was placed in three separate containers.

[0082] In the first container, 10 mL of ethylene glycol was added, and a certain amount of zirconium oxychloride and sodium citrate was accurately weighed by using a balance and added to the container to prepare a precursor solution, wherein the concentration of the zirconium oxychloride was 1.5 mol / L and the concentration of the sodium citrate was 0.1 mol / L.

[0083] In the second container, 10 mL of ethylene glycol was added, and a certain amount of sodium acetate was accurately weighed by using a balance and added to the container, and the mixture was stirred uniformly after the addition to prepare a 0.1 mol / L sodium acetate solution as a pH regulator.

[0084] Finally, the third container was added with 50 mL of ethylene glycol, while the precursor solution and sodium acetate solution were added dropwise at a speed of 0.5 rpm by using a peristaltic pump, the concentration of the precursor solution was 1.5 mol / L, the concentration of the sodium acetate solution was 0.1 mol / L, the pH after dropping was 8.7, and the mixture was placed in a high-temperature oil bath at 140°C for 2 hours to obtain a clear nano-zirconium oxide sol, i.e., a zirconium sol without azobenzene modification.

[0085] Detection Example 1

[0086] The micro-morphology of the azobenzene-modified zirconium oxide sol was characterized by using a scanning electron microscope, and the specific process was as follows:

[0087] The azobenzene-modified zirconia sol prepared in Example 1 was transferred to a centrifuge tube and centrifuged at 8000 rpm for 20 minutes to precipitate the azobenzene-modified zirconia nanoparticles at the bottom of the centrifuge tube. The supernatant was discarded and the precipitate was washed with anhydrous ethanol for 3 times. The washed precipitate was placed in a vacuum drying oven and dried at 60°C for 12 hours to obtain the dried azobenzene-modified zirconia nanoparticle powder.

[0088] As shown in FIG. 1, the azobenzene-modified zirconia sol was prepared according to the following steps: Figure 3 FIG. 2 shows the scanning electron microscope (SEM) image of the azobenzene-modified zirconia nanoparticle powder, and the results show that the zirconia nanoparticles have good dispersibility and uniform particle distribution, and the shape is uniform spherical.

[0089] Test Example 2

[0090] The refractive index of the azobenzene-modified zirconia sol was tested according to the following steps:

[0091] The azobenzene-modified zirconia sol prepared in Example 1 to Example 4 was transferred to a centrifuge tube and centrifuged at 8000 rpm for 20 minutes to precipitate the azobenzene-modified zirconia nanoparticles at the bottom of the centrifuge tube. The supernatant was discarded and the precipitate was washed with anhydrous ethanol for 3 times. The washed precipitate was placed in a vacuum drying oven and dried at 60°C for 12 hours to obtain the dried azobenzene-modified zirconia nanoparticle powder.

[0092] The azobenzene-modified zirconia nanoparticle powder was dispersed in polymethyl methacrylate (PMMA) to prepare a thin film sample. The thin film sample was placed between the two electrode plates of a parallel plate capacitor, and a high voltage power supply was connected. At different electric field strengths, the refractive index change of the thin film sample was measured by ellipsometry. As shown in Table 1, the refractive index of the thin film sample was tested at electric field strengths of 0 kV / m, 1 kV / m, 2 kV / m, 3 kV / m, 4 kV / m and 5 kV / m, respectively.

[0093] Table 1

[0094]

[0095] The results show that with the increase of the electric field strength, the refractive index of the thin film sample shows a regular change, which is due to the cis-trans isomerization of the azobenzene molecules under the action of the electric field, which changes the surrounding electron cloud distribution and molecular polarizability, and further affects the dielectric constant and refractive index of the zirconia nanoparticles, thereby proving that the electric field regulation of the refractive index of the zirconia nanoparticles is realized by the modification of azobenzene.

Claims

1. A method for preparing a zirconia sol for electric field-based control of refractive index, characterized by, The preparation method comprises the following steps: (1) adding a zirconium source and a chelating agent into an organic solvent to prepare a precursor solution; (2) adding a base source into the organic solvent to prepare a pH regulator; (3) simultaneously adding the precursor solution prepared in step (1) and the pH regulator prepared in step (2) into the organic solvent, and heating by an oil bath to obtain a zirconia sol; (4) dissolving an azobenzene compound into an organic solvent to prepare an azobenzene modifier, the azobenzene compound being 4-aminoazobenzene or 2-(4-hydroxyphenylazo)benzoic acid, and the mole percentage of the azobenzene compound in the azobenzene modifier being 0.01% to 0.1%; adding the azobenzene modifier into the zirconia sol prepared in step (3) to obtain an azobenzene-modified zirconia sol, the stirring speed being 100 rpm to 500 rpm, the stirring temperature being 30 ℃ to 60 ℃, and the stirring time being 2 h to 6 h.

2. The method of claim 1, wherein the zirconia sol is prepared by the method of electric field regulation of refractive index, characterized by, In step (1), the zirconium source is zirconium oxychloride or zirconyl nitrate, and the mole percentage of the zirconium source in the precursor solution is 1% to 3%. The chelating agent is sodium citrate, ethylenediamine acetic acid, triethanolamine or ammonium citrate, and the mole percentage of the chelating agent in the precursor solution is 0.05% to 1%.

3. The method of claim 1, wherein the zirconia sol is prepared by the method of controlling the refractive index based on the electric field. In step (2), the base source is sodium acetate or sodium carbonate, and the mole percentage of the base source in the pH regulator is 0.05% to 1%.

4. The method of claim 1, wherein the zirconia sol is prepared by the method of electric field regulation of refractive index, characterized in that, In step (3), the dropping is performed by using a peristaltic pump, the speed of the peristaltic pump being 0.2 rpm to 0.5 rpm, and the pH after dropping being 8.5 to 8.

7.

5. The method of claim 1, wherein the zirconia sol is prepared by the method of electric field regulation of refractive index, characterized in that, In step (3), the temperature of the oil bath heating is at least 140 ℃, and the time is at least 2 h.

6. A zirconia sol based on electric field controlled refractive index, which is prepared by the preparation method according to any one of claims 1 to 5.

7. The electric field regulated refractive index zirconia sol of claim 6, wherein, The refractive index of the zirconia sol is 1.55 to 1.

60.

8. Use of the zirconia sol according to claim 6 or claim 7 in intelligent optical sensors, tunable optical filters and dynamic focusing lenses.

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