A preparation method of mesoporous zirconia thin film

Abstract

The present invention provides a method for preparing a mesoporous zirconia thin film, comprising: (1) preparing a mixed solution of a benign solvent and a pore-expanding agent; the benign solvent is one or a mixture of tetrahydrofuran and methanol; the pore-expanding agent is selected from one or several of cyclohexane, n-hexane, decalin, and tetradecene; (2) dissolving a catalytic amount of an organic alkanolamine catalyst and a nonionic surfactant into the above-mentioned mixed solution, and stirring until a clear solution is obtained; (3) dissolving a zirconium source into the above-mentioned clear solution, and stirring for pre-hydrolysis at room temperature; (4) dropping the solution pre-hydrolyzed in step (3) onto the surface of a flat substrate, and after treatment, obtaining a mesoporous zirconia thin film. The present invention adopts a simple mixing system, which is completely miscible among the systems, without considering the appearance of the microemulsion structure of the system, nor the participation of other auxiliary agents or dispersants. Therefore, the operation is simple and the repetition rate is high, and it can be applied to large-scale industrial production.

Description

Technical Field

[0001] The present invention relates to the field of preparation of mesoporous zirconia, and particularly to a method for preparing a mesoporous zirconia thin film. Background Art

[0002] Zirconia is a coating material with great development potential, having strong chemical stability, high dielectric constant, low conductivity and good biocompatibility, so it is very important for application research in various fields. In the preparation of coatings, the most commonly used method at present is thermal spraying technology, which has the characteristics of dense grain packing and low porosity. However, with the in-depth use scenarios of zirconia coatings, more functional requirements are continuously put forward. For example, in the biomedical system, the zirconia coating of bioplant implants not only requires excellent mechanical properties and good biocompatibility, but also needs to carry a sufficient amount of anti-inflammatory pharmaceutical molecules or growth factors with strong osteogenic induction ability. Mesoporous zirconia thin films have received increasing attention because of their large specific surface area and pore diameters suitable for the loading and slow release of pharmaceutical molecules.

[0003] At present, there are two methods for preparing mesoporous zirconia: the hard template method and the soft template method.

[0004] The hard template method is also known as the nanocasting method. It mainly uses rigid mesoporous solid materials as "sacrificial templates" (such as mesoporous carbon, alumina, and silica, etc.). First, an organic or inorganic precursor is poured into the pores, and then the mesoporous material of the inverse template similar to the template skeleton is formed through in-situ transformation, cross-linking, and curing of the precursor. Finally, the target mesoporous material is obtained after removing the hard template. This method is rather demanding in the selection of templates, so it is difficult to be used on a large scale. The soft template method is the most commonly used method for synthesizing mesoporous zirconia. First, strong charge or hydrogen bond interactions occur between flexible surfactant molecules and zirconium sources, and then they are co-assembled to form a thermodynamically stable and structurally ordered mesoscopic structure of organic-inorganic or organic-organic composites. Then, the template agent is removed by calcination or extraction methods to obtain mesoporous zirconia with a specific structure. Currently, ionic surfactants (such as sodium dodecyl sulfate and cetyltrimethylammonium bromide) are commonly used as template agents to prepare mesoporous zirconia by hydrothermal method or sol-gel method. However, the mesoporous zirconia synthesized by this method is all nanoparticles, and it is very difficult to prepare mesoporous zirconia thin films. This is mainly attributed to the fact that the hydrolysis rate of the zirconium source is difficult to control, and its hydrolysis and cross-linking sol-gel process is too fast. At the same time, due to the strong electrostatic force of ionic surfactants, the hydrolysis products of the zirconium source and the surfactant are co-assembled into a mesoscopic structure and rapidly precipitate in the form of particles with the continuous increase of the cross-linking degree, unable to form a continuous thin film. In addition, limited by the size of ionic surfactants, the pore size of its products is relatively small, only controllable within 2 - 7 nm, which cannot meet the application requirements in the biomedical field. Therefore, it is of great significance to find a new method for synthesizing mesoporous zirconia and prepare mesoporous zirconia thin films with larger pore sizes. Summary of the Invention

[0005] The present invention provides a method for preparing a mesoporous zirconia thin film, which solves the problem of the small pore size of the mesoporous zirconia thin film manufactured in the prior art.

[0006] The technical solution of the present invention is realized as follows:

[0007] A method for preparing a mesoporous zirconia thin film, comprising:

[0008] (1) Prepare a mixed solution of a benign solvent and a pore-expanding agent, wherein the concentration of the pore-expanding agent in the solution is 2 - 10 wt%; the benign solvent is one or a mixture of tetrahydrofuran and methanol; the pore-expanding agent is selected from one or several of cyclohexane, n-hexane, decalin, and tetradecene;

[0009] (2) Dissolve a catalytic amount of an organic alkanolamine catalyst and a non-ionic surfactant into the above mixed solution and stir until a clear solution is obtained;

[0010] (3) Dissolve the zirconium source into the above clear solution and stir for pre-hydrolysis at room temperature;

[0011] (4) Drop the solution after pre-hydrolysis in step (3) on the surface of a flat substrate, volatilize it at room temperature, and then dry it. Heat the dried product from room temperature to 400 - 700 °C under air conditions and hold for 0.5 - 12 h to obtain a mesoporous zirconia thin film.

[0012] In some embodiments, the organic alkanolamine catalyst is selected from one or more of methyldiethanolamine, triethanolamine, diethanolamine, and isopropanolamine.

[0013] In some embodiments, the concentration of the organic alkanolamine catalyst in the clarified solution is 0.05 - 0.5 wt%, and the concentration of the surfactant is 0.25 - 1.25 wt%.

[0014] In some embodiments, the rotation speed of the stirring is 200 - 1800 revolutions per minute.

[0015] In some embodiments, the non-ionic surfactant is poloxamer F127.

[0016] In some embodiments, the zirconium source is selected from one or more of zirconium acetylacetonate, zirconocene dichloride, tetrabutyl zirconate, and tetrapropyl zirconate.

[0017] In some embodiments, the concentration of the zirconium source is 0.5 - 3.0 wt%.

[0018] In some embodiments, the volatilization time is more than 12 h.

[0019] In some embodiments, the drying temperature is 45 - 110 °C.

[0020] In some embodiments, the mesoporous zirconia thin film has a complete thin film structure.

[0021] In some embodiments, the pore size of the mesoporous zirconia thin film is 30 - 40 nm.

[0022] The present invention has the following beneficial effects compared with the prior art:

[0023] (1) The present invention adopts a double organic solvent stepwise volatilization system, utilizes the weak polarity and fast volatilization characteristics of the benign solvent to form a lyotropic liquid crystal phase, and further obtains a mesoporous thin film.

[0024] (2) The present invention adopts a non-benign organic solvent with a slow volatilization rate to achieve the effect of expanding the pores of the thin film.

[0025] (3) The present invention adopts a simple mixing system, in which the systems are completely miscible with each other. There is no need to consider the emergence of the microemulsion structure of the system, nor the participation of other auxiliary agents or dispersants. Therefore, the operation is simple and the repetition rate is high, and it can be applied to large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0027] Figure 1 It is a scanning electron microscope (SEM) image of the characteristics of the mesoporous zirconia thin film in Example 1.

[0028] Figure 2 It is the nitrogen adsorption-desorption isotherm of the characteristics of the mesoporous zirconia thin film in Example 1.

[0029] Figure 3 It is the pore size distribution curve of the characteristics of the mesoporous zirconia thin film in Example 1.

[0030] Figure 4 It is a scanning electron microscope (SEM) image of the characteristics of the mesoporous zirconia thin film in Example 2.

[0031] Figure 5 It is the nitrogen adsorption-desorption isotherm of the characteristics of the mesoporous zirconia thin film in Example 2.

[0032] Figure 6 It is the pore size distribution curve of the characteristics of the mesoporous zirconia thin film in Example 2.

[0033] Figure 7 It is a scanning electron microscope (SEM) image of the characteristics of the mesoporous zirconia thin film in Example 3.

[0034] Figure 8 It is the nitrogen adsorption-desorption isotherm of the characteristics of the mesoporous zirconia thin film in Example 3.

[0035] Figure 9 It is the pore size distribution curve of the characteristics of the mesoporous zirconia thin film in Example 3. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0036] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Apparently, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0037] The present invention uses the least basic alkanolamine as a catalyst to control the hydrolysis and crosslinking rates of the organozirconium source. By using a non-ionic surfactant, the assembly with the hydrolysis products of the zirconium source is mainly through relatively weak hydrogen bond forces and hydrophilic / hydrophobic forces, further controlling the sol-gel process of the system and suppressing the phase separation precipitation of the products. A two-step volatile system of double organic solvents is adopted. The benign solvent is a volatile weakly polar solvent (such as methanol and tetrahydrofuran, etc.). After the zirconium source and the surfactant are dissolved, the synergistic effect between the hydrolysis products of the zirconium source and the non-ionic surfactant molecules is very weak. However, during the rapid volatilization of the benign solvent, it can promote the assembly at the organic-inorganic interface and the further hydrolysis and crosslinking of inorganic species, forming a lyotropic liquid crystal phase on a flat substrate, and a mesoporous film is obtained after curing. By using a two-step volatile system of double organic solvents, on the basis of further controlling the hydrolysis rate of the organozirconium source, through the first volatilization of the benign organic solvent and the pore-expanding effect of a small amount of non-benign organic solvent, the preparation of larger pore diameters is realized. In the preparation method, the reaction system simply blends the organic solvent, surfactant, catalyst, and zirconium source and coats them on the substrate, and then volatilizes at room temperature and calcines at high temperature. Therefore, the operation is simple and the repetition rate is high, and it is applicable to large-scale industrial production.

[0038] The reagents used in the following examples are all commercially available.

[0039] Example 1

[0040] A method for preparing a mesoporous zirconia film, comprising the following steps:

[0041] (1) Mix 48 mL of tetrahydrofuran and 2 mL of cyclohexane, add 0.05 g of triethanolamine and 0.25 g of F127, and stir at a high speed to obtain a colorless and transparent solution;

[0042] The above stirring speed is 200 revolutions per minute, and the time is 10 min; the stirrer used can be a turbine stirrer, a paddle stirrer, a magnetic stirrer, a magnetic heating stirrer, a pitched blade stirrer, or a mechanical stirrer;

[0043] (2) Dissolve 0.5 mL of tetrabutyl zirconate in the above clear solution and pre-hydrolyze it at room temperature for 0.5 h;

[0044] (3) Drop the above pre-hydrolyzed solution onto ordinary glass, leave it at room temperature for more than 12 hours, and then place it in an oven at 70 °C for drying for 2 hours;

[0045] (4) Place the product of step (3) in an air atmosphere, raise the temperature from room temperature to 700 °C, and hold for 1 h to obtain a mesoporous zirconia thin film material.

[0046] The prepared mesoporous zirconia thin film has a complete thin film structure, its pore size is 30.2 nm, and its specific surface area is 178.5 m 2 / g.

[0047] Example 2

[0048] A preparation method of a mesoporous zirconia thin film, comprising the following steps:

[0049] (1) Mix 45 mL of methanol and 5 mL of decahydronaphthalene, add 0.2 g of methyldiethanolamine and 1.2 g of F127, and stir at high speed to obtain a colorless and transparent solution;

[0050] The above stirring speed is 1000 revolutions per minute and the time is 30 min; the stirrer used can be a turbine stirrer, a paddle stirrer, a magnetic stirrer, a magnetic heating stirrer, a pitched blade stirrer, or a mechanical stirrer;

[0051] (2) Dissolve 1.2 mL of tetrapropyl zirconate in the above clarified solution and pre-hydrolyze it at room temperature for a reaction time of 0.5 h;

[0052] (3) Drop the above pre-hydrolyzed solution onto ordinary glass, leave it at room temperature for more than 12 hours, and then place it in an oven at 50 °C for drying for 2 hours;

[0053] (4) Place the above product in an air atmosphere, raise the temperature from room temperature to 550 °C, and hold for 3 h to obtain a mesoporous zirconia thin film material.

[0054] The prepared mesoporous zirconia thin film has a complete thin film structure, its pore size is 37.3 nm, and its specific surface area is 190.5 m 2 / g.

[0055] Example 3

[0056] A preparation method of a mesoporous zirconia thin film, comprising the following steps:

[0057] (1) Mix 23 mL of tetrahydrofuran, 23 mL of methanol and 4 mL of tetradecene, add 0.1 g of isopropanolamine and 0.6 g of F127, and stir at high speed to obtain a colorless and transparent solution;

[0058] The stirring speed is 1500 revolutions per minute and the time is 60 min; the stirrer used can be a turbine stirrer, paddle stirrer, magnetic stirrer, magnetic heating stirrer, pitched blade stirrer, or mechanical stirrer;

[0059] (2) Dissolve 0.8 mL of zirconium acetylacetonate in the above-mentioned clear solution and pre-hydrolyze at room temperature for 0.5 h;

[0060] (3) Drop the above-mentioned pre-hydrolyzed solution onto ordinary glass, let it stand at room temperature for more than 12 hours, and then place it in an oven at 100 °C for drying for 2 hours;

[0061] (4) Place the above product in an air atmosphere, raise the temperature from room temperature to 450 °C, and hold for 10 h to obtain a mesoporous zirconia thin film material.

[0062] The prepared mesoporous zirconia thin film has a complete film structure, with a pore size of 40.7 nm and a specific surface area of 215.9 m 2 / g.

[0063] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a mesoporous zirconia thin film, characterized in that, Including: (1) Prepare a mixed solution of a benign solvent and a pore-expanding agent, where the concentration of the pore-expanding agent in the mixed solution is 2 - 10 wt%; the benign solvent is one or a mixture of tetrahydrofuran and methanol; the pore-expanding agent is selected from one or several of cyclohexane, n-hexane, decalin, and tetradecene; (2) Dissolve a catalytic amount of an organic alkanolamine catalyst and a non-ionic surfactant in the above mixed solution, and stir until a clear solution is obtained; (3) Dissolve the zirconium source in the above clear solution, and stir for pre-hydrolysis at room temperature; (4) Drop the solution after pre-hydrolysis in step (3) onto the surface of a flat substrate, volatilize at room temperature, and then dry. Heat the dried product from room temperature to 400 - 700 °C under air conditions and hold for 0.5 - 12 h to obtain a mesoporous zirconia thin film.

2. The preparation method of a mesoporous zirconia thin film according to claim 1, wherein, The organic alkanolamine catalyst is selected from one or several of methyldiethanolamine, triethanolamine, diethanolamine, and isopropanolamine.

3. The preparation method of a mesoporous zirconia thin film according to claim 1, characterized in that, The concentration of the organic alkanolamine catalyst in the clear solution is 0.05 - 0.5 wt%.

4. The preparation method of a mesoporous zirconia thin film according to claim 1 or 3, characterized in that, The concentration of the surfactant in the clear solution is 0.25 - 1.25 wt%.

5. The preparation method of a mesoporous zirconia thin film according to claim 1, characterized in that, The rotation speed of the stirring is 200 - 1800 revolutions per minute.

6. The preparation method of a mesoporous zirconia thin film according to claim 1, characterized in that, The zirconium source is selected from one or several of zirconium acetylacetonate, zirconocene dichloride, tetrabutyl zirconate, and tetrapropyl zirconate.

7. A method for preparing a mesoporous zirconia thin film according to claim 1, characterized in that, The concentration of the zirconium source is 0.5 - 3.0 wt%.

8. The preparation method of a mesoporous zirconia thin film according to claim 1, characterized in that, The mesoporous zirconia thin film has a complete film structure.

9. The preparation method of a mesoporous zirconia thin film according to claim 1, characterized in that, The pore size of the mesoporous zirconia thin film is 30 - 40 nm.

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