A three-dimensional micro-nano transparent glass structure and its preparation method and application

Abstract

The present invention provides a micro-nano transparent glass three-dimensional structure, and its preparation method and application. The preparation method uses silica nanoparticles modified with photoresponsive ligands as raw materials. In the presence of a photoinitiator, no additional photoresponsive monomers or cross-linking agents need to be added during the subsequent laser processing, and photocrosslinking can be directly achieved. The nanoparticles in the obtained micro-nano three-dimensional glass green body are in a tightly cross-linked state. At the same time, based on this state, the present invention sinters the obtained micro-nano three-dimensional glass green body at a low temperature of no more than 700°C, so that a glass network structure can be formed between the nanoparticles, and finally a transparent micro-nano glass three-dimensional structure is obtained. According to tests, the shrinkage rate of the micro-nano transparent glass three-dimensional structure provided by the present invention is less than 5%. It can be seen that the present invention not only achieves low-temperature sintering, but also obtains a micro-nano transparent glass three-dimensional structure with a low shrinkage rate, solving the problem that the existing technology cannot achieve both.

Description

Technical Field

[0001] The present invention belongs to the field of glass technology, and in particular relates to a three-dimensional micro-nano transparent glass structure and a preparation method and application thereof. Background Art

[0002] Glass is widely used in optics, biology, and medicine due to its excellent optical transparency, mechanical properties, thermal stability, and chemical stability. Traditional glass forming methods, mainly based on glass blowing and mold pressing, have difficulty in fabricating complex three-dimensional (3D) structures.

[0003] Currently, glass 3D structure forming technologies are primarily categorized into two categories: direct glass 3D printing and indirect glass 3D printing. Direct glass 3D printing primarily includes selective laser melting (SLM), direct energy deposition (DED), and fused deposition modeling (FDM). These methods utilize an extremely powerful energy source to generate temperatures (>1600°C) sufficient to melt silica, enabling the fabrication of complex 3D glass structures. However, these methods suffer from high temperatures and millimeter-level processing accuracy, making them incapable of producing high-precision glass components. Indirect glass 3D printing primarily includes direct ink writing (DIW), stereolithography (SLA), digital light processing (DLP), and computed axial lithography (CAL). These methods first print a 3D glass green body, then remove organic components from the structure through degreasing and sintering, ultimately yielding a transparent silica glass body. This process results in a certain amount of structural shrinkage. However, the manufacturing resolution of the above methods is usually above tens of microns, which cannot meet the high-resolution and high-precision requirements of micro-nano glass devices, and seriously hinders the application of glass materials in the field of micro-nano engineering, especially in the field of micro-nano optical information.

[0004] Based on this, researchers are studying the fabrication of micro-nanoglass 3D structures. For example, Xiewen Wen's group at the Hong Kong Polytechnic University used silica nanoparticles surface-modified with polyethylene glycol to successfully print glass microstructures with a characteristic size of 170 nm after sintering at 1100°C. The structure exhibited a shrinkage of 14% and a transparency exceeding 90%. However, the high sintering temperature (1100°C) makes the fabrication of these 3D glass structures difficult to integrate with other devices that are not resistant to high temperatures, limiting their applications. Meanwhile, J. Bauer's group at the Karlsruhe Institute of Technology in Germany used cage-type polysilsesquioxane to print 3D glass structures with a characteristic size of 97 nm after low-temperature heat treatment. The structure exhibited a shrinkage of 42% and a transparency exceeding 95%. However, large shrinkage (>20%) can lead to strain mismatch between the structure and the substrate, which can easily cause deformation of the 3D structure. While this defect can be offset by printing an additional sacrificial substrate, this increases printing time and reduces manufacturing efficiency. Therefore, current technology still cannot achieve the fabrication of micro-nanotransparent 3D glass structures that combine low sintering temperature and low shrinkage. Summary of the Invention

[0005] In view of this, the present invention aims to provide a micro-nano transparent glass three-dimensional structure and its preparation method and application. The preparation method has a low sintering temperature and the prepared micro-nano transparent glass three-dimensional structure has a low shrinkage rate of less than 5%.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a method for preparing a three-dimensional micro-nano transparent glass structure, comprising the following steps:

[0008] S1: mixing a solution of silica nanoparticles modified with a photoresponsive ligand and a photoinitiator, and drying the mixture to obtain a glass precursor photoresist;

[0009] The photoresponsive ligand includes any one or more of methacrylic acid, methacryloxytrimethoxysilane or styryltriethoxysilane;

[0010] S2: Laser processing a glass slide loaded with a glass precursor photoresist to obtain a micro-nano three-dimensional glass green body, which is then sintered and cooled to obtain a micro-nano transparent glass three-dimensional structure;

[0011] The sintering temperature does not exceed 700°C.

[0012] Preferably, the laser processing is femtosecond laser processing.

[0013] Preferably, the laser exposure time in the laser processing is 400-1000 μs, and the power is 11-29 mW.

[0014] Preferably, the sintering is carried out according to the following procedure:

[0015] Heat to 160-240°C and keep warm for 2-3 hours;

[0016] Heat to 400-450°C and keep warm for 3-4 hours;

[0017] Heat to 650~700℃ and keep warm for 5~10 hours.

[0018] Preferably, the heating rate during sintering is 1-3°C / min.

[0019] Preferably, the mass fraction of the solute in the photoresponsive ligand-modified silica nanoparticle solution is 30-60%.

[0020] Preferably, the particle size of the silica nanoparticles is 15-30 nm.

[0021] Preferably, the solvent in the photoresponsive ligand-modified silica nanoparticle solution includes any one or more of propylene glycol methyl ether, ethanol, isopropanol, n-butanol, ethylene glycol or propylene glycol.

[0022] Preferably, the photoinitiator includes any one or more of tetraethyl Michler's ketone, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide or 7-diethylamino-3-thenoylcoumarin.

[0023] Preferably, the mass ratio of the photoresponsive ligand to the silica nanoparticles is 22:78 to 18:82.

[0024] Preferably, the mass ratio of the photoresponsive ligand-modified silica nanoparticles to the photoinitiator is 20:(0.5-1.5).

[0025] Preferably, the mixing is carried out until the photoinitiator is completely dissolved.

[0026] Preferably, the drying temperature is 50-80° C. and the drying time is 10-30 h.

[0027] Preferably, the micro-nano three-dimensional glass green body is developed and then sintered.

[0028] Preferably, the developing is performed in an ethanol solution.

[0029] In a second aspect, the present invention provides a three-dimensional micro-nano transparent glass structure prepared by the above-mentioned preparation method, wherein the shrinkage rate of the three-dimensional micro-nano transparent glass structure is less than 5%.

[0030] In a third aspect, the present invention provides an application of a micro-nano transparent glass three-dimensional structure prepared by the above preparation method in the preparation of an optical fiber integrated device.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] The present invention provides a method for preparing a three-dimensional micro-nano transparent glass structure. This method uses silica nanoparticles modified with photoresponsive ligands as the raw material. In the presence of a photoinitiator, direct photocrosslinking is achieved without the need for adding additional photoresponsive monomers or crosslinking agents during subsequent laser processing. The resulting micro-nano three-dimensional glass green body exhibits a tightly crosslinked nanoparticle state. Furthermore, based on this state, the present invention sinters the resulting micro-nano three-dimensional glass green body at a low temperature of no more than 700°C to form a glass network structure between the nanoparticles, ultimately yielding a transparent micro-nano three-dimensional glass structure.

[0033] In the present invention, on the one hand, silica nanoparticles modified with photoresponsive ligands are sintered at low temperatures, which facilitates the formation of a porous three-dimensional micro-nano glass structure. On the other hand, the photoresponsive ligands directly cross-link the silica nanoparticles, which also helps retain some pores. As a result, the resulting three-dimensional micro-nano transparent glass structure possesses a porous structure, contributing to a low structural shrinkage rate. Testing has shown that the shrinkage rate of the three-dimensional micro-nano transparent glass structure provided by the present invention is less than 5%.

[0034] In summary, the present invention not only achieves low-temperature sintering but also produces a three-dimensional micro-nano transparent glass structure with low shrinkage, resolving the problem of the prior art in being unable to achieve both. Furthermore, the preparation method provided by the present invention is simple and cost-effective, facilitating industrial or industrialized production. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a schematic diagram of the process of obtaining a glass precursor photoresist according to the present invention;

[0036] Figure 2 This is a schematic diagram of the process of femtosecond laser two-photon polymerization;

[0037] Figure 3 Schematic diagram of the six different glass three-dimensional structure models designed;

[0038] Figure 4 Schematic diagram of the femtosecond laser two-photon polymerization process of micro-nano three-dimensional glass green body;

[0039] Figure 5 Schematic diagram of the process for sintering the developed sample;

[0040] Figure 6 The SEM images of the six different glass three-dimensional structures prepared are shown below;

[0041] Figure 7The comparison diagrams of the dimensions of glass three-dimensional structures 1 to 4 before and after sintering are shown in different views.

[0042] Figure 8 is an optical microscope image of structure 5;

[0043] Figure 9 This is the roughness characterization result diagram of the surface of structure 6;

[0044] Figure 9 a in the figure is the SEM image of structure 6 used in the test. Figure 9 b is the surface profile obtained using atomic force microscopy. Figure 9 c in the figure is the contour image extracted from the white line position in b;

[0045] Figure 10 is the Raman spectrum of structure 6;

[0046] Figure 11 Transmission electron microscopy (TEM) image of a thin slice extracted from structure 6 using focused ion beam cutting. DETAILED DESCRIPTION

[0047] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0048] In view of the problem that the existing technology cannot achieve low-temperature sintering while obtaining a micro-nano transparent glass three-dimensional structure with low shrinkage, the present invention provides a method for preparing a micro-nano transparent glass three-dimensional structure, comprising the following steps:

[0049] S1: mixing a solution of silica nanoparticles modified with a photoresponsive ligand and a photoinitiator, and drying the mixture to obtain a glass precursor photoresist;

[0050] S2: Laser processing is performed on a glass slide carrying a glass precursor photoresist to obtain a micro-nano three-dimensional glass green body, which is then sintered and cooled to obtain a micro-nano transparent glass three-dimensional structure.

[0051] In the present invention, a glass precursor photoresist is first synthesized. The glass precursor photoresist is primarily composed of photoresponsive ligand-modified silica nanoparticles and a photoinitiator. In some embodiments of the present invention, a solution of photoresponsive ligand-modified silica nanoparticles and the photoinitiator are preferably mixed and then dried to obtain the glass precursor photoresist.

[0052] In the present invention, a high solute mass fraction in the photoresponsive ligand-modified silica nanoparticle solution increases the risk of nanoparticle agglomeration, affecting the subsequent preparation of the photoresist. Therefore, the present invention preferably has a solute mass fraction of 30% to 60% in the photoresponsive ligand-modified silica nanoparticle solution, such as 30%, 35%, 40%, 45%, 50%, 55%, or 60%. The solvent in the photoresponsive ligand-modified silica nanoparticle solution includes any one or more of propylene glycol methyl ether, ethanol, isopropanol, n-butanol, ethylene glycol, or propylene glycol, preferably propylene glycol methyl ether; the photoresponsive ligand includes any one or more of methacrylic acid, methacryloxytrimethoxysilane, or styryltriethoxysilane, preferably methacrylic acid, which not only provides efficient crosslinking ability but also rapidly forms a crosslinked network through its double bonds under the action of a photoinitiator; the particle size of the silica nanoparticles is preferably 10 to 30 nm, such as 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, etc., which can improve manufacturing accuracy. In the present invention, the photoresponsive ligand-modified silica nanoparticle solution can be purchased directly or prepared according to content well known to those skilled in the art. The mass ratio of the photoresponsive ligand to the silica nanoparticles is 22:78 to 18:82, such as 18:82, 19:81, 20:80, 21:79 or 22:78.

[0053] In some specific embodiments of the present invention, a solution of photoresponsive ligand-modified silica nanoparticles is preferably oscillated and mixed with a photoinitiator, followed by sonication until the photoinitiator is completely dissolved, yielding a light yellow transparent solution. The photoinitiator may include any one or more of tetraethyl Michler's ketone, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, or 7-diethylamino-3-thenoylcoumarin. The mass ratio of the photoresponsive ligand-modified silica nanoparticles to the photoinitiator is 20:(0.5-1.5), such as 20:0.5, 20:0.8, 20:1, 20:1.2, or 20:1.5. The light yellow transparent solution is then baked in an oven at 50-80°C for 10-30 hours, preferably at 60-75°C for 10-25 hours, and more preferably at 65°C for 20 hours, to reduce the solvent content in the solution, yielding a dark yellow transparent solution, i.e., the glass precursor photoresist.

[0054] It should be noted that the present invention modifies silica nanoparticles with photoresponsive ligands, and in the subsequent processing, photocrosslinking can be achieved without adding additional photopolymerizable monomers or crosslinking agents, which has the advantages of fewer material components, simple configuration and low cost.

[0055] According to the present invention, after obtaining the glass precursor photoresist, a portion of the glass precursor photoresist is preferably pipetted and dripped onto a glass slide to obtain a glass slide carrying the glass precursor photoresist, which is then laser processed. The glass slide is preferably a quartz glass slide that can withstand temperatures of nearly 1000°C. The size of the glass slide can be designed as needed, for example, a 2 cm × 2 cm × 200 μm glass slide.

[0056] In some embodiments of the present invention, the glass slide carrying the glass precursor photoresist is preferably baked on a hot plate at about 100° C. for 60 to 120 s, preferably 90 s, to remove most of the volatile solvent before laser processing.

[0057] In some embodiments of the present invention, the laser processing is femtosecond laser processing. The present invention has no particular limitation on the technical means of femtosecond laser processing, and the processing can be performed according to the knowledge of those skilled in the art.

[0058] In some specific embodiments of the present invention, the schematic diagram of the processing light path of the femtosecond laser processing is as follows: Figure 2 As shown, a glass slide (i.e., sample) loaded with a glass precursor photoresist is preferably placed on a Z-axis nanopiezoelectric stage, with the slide facing the oil-immersion objective. A femtosecond laser beam, emitted by a titanium-sapphire laser, passes through a half-wave plate, a polarizing beam splitter, and a beam expander before entering a scanning galvanometer. The scanning galvanometer deflects the laser beam by controlling the reflection angle of the reflector, achieving two-dimensional motion in the XY plane. After emitting from the scanning galvanometer, the laser beam passes through a 4f lens assembly and a reflector before entering an oil-immersion objective (60×, 1.4 NA). The oil-immersion objective focuses the laser beam onto the interior of the glass precursor photoresist. The sample's Z-axis position is manually adjusted to ensure the initial spot is located at the interface between the quartz slide and the glass precursor photoresist. Subsequently, the three-dimensional structure model to be processed is sequentially imported into the processing software, and the laser exposure time is set to 400-1000 μs, such as 400 μs, 500 μs, 600 μs, 700 μs, 800 μs, 900 μs, or 1000 μs. The laser processing power is adjusted to 11-29 mW using an attenuator, such as 11 mW, 13 mW, 15 mW, 17 mW, 20 mW, 23 mW, 25 mW, 27 mW, or 29 mW. Finally, the Z-axis movement of the nanopiezoelectric stage is combined with the X-axis and Y-axis scanning of the scanning galvanometer to achieve efficient processing of the micro-nano three-dimensional glass blank. It should be noted that the above exposure time and processing power are selected after screening and optimization of the present invention. If the exposure time is too short and the processing power is too low, molding will not be possible. Conversely, if it is too high, the structure will be too large and deviate from the design size.

[0059] In the present invention, the presence of photoresponsive ligands modified on the surface of silica nanoparticles during the femtosecond laser processing process enables photopolymerization, even without the addition of additional photocrosslinking monomers or crosslinking agents, allowing the nanoparticles to directly crosslink. Therefore, the silica nanoparticles modified with photoresponsive ligands in the glass precursor photoresist undergo direct photocrosslinking under femtosecond laser two-photon polymerization, ultimately forming a three-dimensional structure along the laser scanning trajectory.

[0060] Schematically, the femtosecond laser two-photon polymerization process of micro-nano three-dimensional glass green body with tightly cross-linked nanoparticles is as follows Figure 4 shown.

[0061] According to the present invention, after obtaining the micro-nano three-dimensional glass green body, it is sintered at a low temperature and then cooled to room temperature to obtain a micro-nano transparent glass three-dimensional structure.

[0062] In the present invention, the low-temperature sintering is preferably carried out in a muffle furnace, and the sintering temperature does not exceed 700° C. Specifically, in some embodiments of the present invention, the sintering is carried out according to the following procedure:

[0063] Heat to 160-240°C and keep warm for 2-3 hours;

[0064] Heat to 400-450°C and keep warm for 3-4 hours;

[0065] Heat to 650~700℃ and keep warm for 5~10 hours.

[0066] For example, it may be any of the following procedures:

[0067] Procedure 1:

[0068] Raise the temperature to 200°C and keep warm for 2 h;

[0069] Heat to 400°C and keep warm for 3 h;

[0070] Heat to 650℃ and keep warm for 5 hours.

[0071] Procedure 2:

[0072] Heat to 180°C and keep warm for 2.5 h;

[0073] Heat to 420°C and keep warm for 3 h;

[0074] Heat to 680℃ and keep warm for 6 hours.

[0075] Procedure 3:

[0076] Heat to 220°C and keep warm for 3 h;

[0077] Heat to 450°C and keep warm for 3 h;

[0078] Heat to 700℃ and keep warm for 8 h.

[0079] However, in the present invention, the sintering procedure is not limited to the above three procedures, and any sintering procedure can be performed as long as the temperature and time set in the above sintering procedure are met.

[0080] During the sintering process, the heating rate is 1-3°C / min, such as 1°C / min, 1.5°C / min, 2°C / min, 2.5°C / min, or 3°C / min. The heating rate should generally be neither too high nor too low. A too low heating rate will result in prolonged structure preparation and waste of energy, while a too high heating rate will cause rapid combustion of organic matter within the structure, reducing the quality of the structure.

[0081] It should be noted that the present invention heats the glass to 160-240°C and holds it for 2-3 hours to remove residual solvent and moisture from the structure; heats the glass to 400-450°C and holds it for 3-4 hours to remove organic matter; and finally heats the glass to 650-700°C and holds it for 5-10 hours before naturally cooling it to room temperature. During this process, the photoresponsive ligand-modified silica nanoparticles form a glass network, ultimately yielding a transparent three-dimensional micro-nanoglass structure. Furthermore, because the nanoparticles in the three-dimensional glass green body are tightly cross-linked after laser processing, they form a densely packed arrangement after organic matter removal. By setting an appropriate heating profile and holding time, sintering at a lower temperature (650-700°C) yields a transparent, low-shrinkage, and high-fidelity micro-nanoglass three-dimensional structure. It should be noted that if the temperature in the final step is below 650-700°C, the organic residue will not be completely removed.

[0082] In some preferred embodiments of the present invention, the micro-nano 3D glass green body is developed and then sintered. For example, the sample processed by femtosecond laser is placed in an ethanol solution for approximately 20 to 50 minutes, preferably 30 minutes, to remove uncrosslinked nanoparticles and retain only the formed 3D glass green body structure.

[0083] Scanning electron microscopy (SEM) was used to characterize the three-dimensional micro-nano transparent glass structure produced by the above-mentioned preparation method, demonstrating excellent three-dimensional forming quality and high fidelity. Measurements showed minimal structural shrinkage during low-temperature sintering, with a linear shrinkage of less than 5%. Transmission electron microscopy (TEM) examination of the interior of the structure revealed the presence of nanopores within the three-dimensional micro-nano transparent glass structure after low-temperature sintering, with an average diameter of approximately 6 nm.

[0084] The present invention also proves the transparency of the three-dimensional structure of micro-nano glass through an optical microscope, and the results show that the transparency of the micro-nano glass structure is high.

[0085] The above results show that the three-dimensional structure of the micro-nano transparent glass provided by the present invention is a transparent nanoporous glass, which not only has a low sintering temperature, but also has a low shrinkage rate and high transparency.

[0086] In summary, the preparation method provided by the present invention first provides a glass precursor photoresist that can be directly cross-linked with silica nanoparticles that can be polymerized by femtosecond laser two-photon polymerization. The material configuration is simple and the cost is low. It realizes the low-temperature and low-shrinkage processing of three-dimensional transparent glass with a characteristic size of 100 nanometers, providing a reference for the development of various glass precursor photoresists. Then, a femtosecond laser with high processing precision is used to realize the processing of micro-nano three-dimensional glass green body with tightly cross-linked nanoparticles. The three-dimensional molding effect is good, breaking through the limits of existing glass manufacturing processes. Finally, a low-temperature sintering post-processing process is adopted. By setting a suitable heating curve and holding time, the structure can be sintered transparently at low temperature sintering, and finally a micro-nano glass three-dimensional structure with high transparency is obtained. During the sintering process, the structure only produces a linear shrinkage of less than 5%, with high fidelity.

[0087] The above preparation method and the prepared micro-nano transparent glass three-dimensional structure have great application value in many application fields such as optics, biology and medicine.

[0088] To further illustrate the present invention, the following examples provide a detailed description. The methacrylic acid-modified silica nanoparticle solution used in the following examples was purchased from Shanghai Jiute Nanomaterials Technology Co., Ltd. The product was methacrylic acid-modified nanosilica sol (40 wt%, solvent: propylene glycol methyl ether). The mass ratio of methacrylic acid to silica nanoparticles (particle size 20 nm) was 22:78.

[0089] Example 1

[0090] 1) Configuration materials: such as Figure 1 As shown in FIG, 2 g of a solution containing methacrylic acid-modified silica nanoparticles (mass fraction of methacrylic acid-modified silica nanoparticles: 40%; solvent: propylene glycol methyl ether) and 40 mg of tetraethyl Michler's ketone (photoinitiator) were oscillated and sonicated until the tetraethyl Michler's ketone was completely dissolved. The resulting solution was then baked in an oven at 65°C for 20 h to reduce the solvent content in the solution, thereby obtaining a glass precursor photoresist.

[0091] 2) Femtosecond laser two-photon polymerization:

[0092] a. Glue coating: Use a pipette to drop 10 µL of glass precursor photoresist onto a quartz glass slide;

[0093] b. Glue baking: Place the slide on a hot plate at 100°C and heat for 90 seconds.

[0094] c. Processing: Use Figure 2 The femtosecond laser two-photon polymerization processing system is used. The baked glass slide is placed on the Z-axis piezoelectric stage as a sample and fixed, with the glass slide facing the oil-immersed objective lens side. The femtosecond laser is emitted by a titanium sapphire laser, and is incident on the scanning galvanometer after passing through a half-wave plate, a polarization beam splitter, and a beam expander. The scanning galvanometer controls the reflection angle of the reflector to achieve the deflection of the laser beam and complete the movement of the laser in the XY two-dimensional plane. After the laser is emitted from the scanning galvanometer, it passes through the 4f lens group and the reflector and enters the oil-immersed objective lens (60×, 1.4 NA). The laser beam is focused inside the glass precursor photoresist through the oil-immersed objective lens. Manually coarsely adjust the Z position of the sample so that the initial light spot is located at the interface between the quartz glass slide and the glass precursor photoresist. Place the sample to be processed such as Figure 3 The six different glass three-dimensional structure models shown in the figure were imported into the processing software in sequence, and the processing parameters (single point exposure time: 800 μs, processing power: 20 mW) were adjusted before processing. In the above processing, the femtosecond laser two-photon polymerization process of the micro-nano three-dimensional glass green body is as follows: Figure 4 shown.

[0095] 3) Development: After processing, remove the sample and place it in an ethanol solution for upside-down development for 30 minutes.

[0096] 4) Low temperature sintering: Figure 5 As shown in the figure, the developed sample is placed in a muffle furnace, and the temperature is raised to 200°C at a heating rate of 1°C / min and kept for 2 hours to remove the residual solvent in the structure. Then the temperature is raised to 400°C at a heating rate of 1°C / min and kept for 3 hours to remove the organic matter in the structure. Subsequently, the temperature is raised to 650°C at a heating rate of 1°C / min and kept for 5 hours. Finally, it is naturally cooled to room temperature to obtain a transparent micro-nano glass three-dimensional structure.

[0097] Characterization

[0098] SEM was used to characterize the morphology of the three-dimensional structure of the glass after low-temperature sintering, such as Figure 6 As shown, the morphology is controllable and the fidelity is high.

[0099] The shrinkage of different glass three-dimensional structures is characterized, such as Figure 7 As shown, structure 1: shrinkage in the X direction is 4.10%, in the Y direction is 4.27%, and in the Z direction is 4.27%; structure 2: shrinkage in the X direction is 4.55%, in the Y direction is 4.44%, and in the Z direction is 4.86%; structure 3: shrinkage in the X direction is 4.85%, in the Y direction is 4.56%, and in the Z direction is 4.86%; structure 4: shrinkage in the X direction is 4.87%, in the Y direction is 4.31%, and in the Z direction is 4.42%; Figure 7shown.

[0100] The transparency of low temperature sintered glass was characterized. The test structure was structure 5. The results are as follows: Figure 8 As shown, the letters under the squares can be clearly seen through an optical microscope, indicating that the low-temperature sintered glass has excellent transparency.

[0101] The roughness of low-temperature sintered glass was characterized. The test structure was structure 6. The characterization was performed on the surface of the micro-cube. The results are as follows: Figure 9 As shown, Figure 9 a in the figure is the SEM image of structure 6 used in the test. Figure 9 b is the surface profile obtained using atomic force microscopy. Figure 9 Figure c is the contour extracted from the white line position in b. The arithmetic mean deviation (Ra) of the contour is 5.6 nm, indicating good surface quality.

[0102] Raman spectroscopy characterization was performed on low temperature sintered glass. The test structure was structure 6. The test results are as follows: Figure 10 As shown, the ω1 and ω3 bands correspond to Si(O 1 / 2 )4 tetrahedral Si-O-Si bridge bending vibration, the ω4 band is attributed to the stretching motion of the Si-O bond. The D1 and D2 lines correspond to the symmetric stretching of the siloxane ring molecule. At 982 cm -1 An additional peak appeared at , indicating the presence of Si-OH in the structure. Raman spectroscopy revealed that the silica nanoparticles sintered, forming a continuous silica network within the glass.

[0103] TEM examination of the interior of the low-temperature sintered glass was performed. The test structure was a thin slice extracted from structure 6 using a focused ion beam. The results showed that nanopores existed inside the low-temperature sintered glass, with an average diameter of 6 nm. Figure 11 shown.

[0104] The above characterization results prove that the three-dimensional microstructure obtained by the preparation method provided by the present invention is a transparent silica glass, which can achieve not only a low sintering temperature but also a low shrinkage rate and high transparency.

[0105] Example 2

[0106] 1) Configuration materials: such as Figure 1 As shown in Figure 2, 3 g of a solution containing methacrylic acid-modified silica nanoparticles (mass fraction of methacrylic acid-modified silica nanoparticles: 40%; solvent: propylene glycol methyl ether) was oscillated and mixed with 60 mg of tetraethyl Michler's ketone (photoinitiator), and ultrasonicated until the tetraethyl Michler's ketone was completely dissolved. The resulting solution was then baked in an oven at 75°C for 16 h to reduce the solvent content in the solution.

[0107] 2) Femtosecond laser two-photon polymerization:

[0108] a. Glue coating: Use a pipette to drop 10 µL of glass precursor photoresist onto a quartz glass slide;

[0109] b. Glue baking: Place the slide on a hot plate at 100°C and heat for 70 seconds.

[0110] c. Processing: Use Figure 2 The femtosecond laser two-photon polymerization processing system is used. The baked glass slide is placed on the Z-axis piezoelectric stage as a sample and fixed, with the glass slide facing the oil-immersed objective lens side. The femtosecond laser is emitted by a titanium sapphire laser, and is incident on the scanning galvanometer after passing through a half-wave plate, a polarization beam splitter, and a beam expander. The scanning galvanometer controls the reflection angle of the reflector to achieve the deflection of the laser beam and complete the movement of the laser in the XY two-dimensional plane. After the laser is emitted from the scanning galvanometer, it passes through the 4f lens group and the reflector and enters the oil-immersed objective lens (60×, 1.4 NA). The laser beam is focused inside the glass precursor photoresist through the oil-immersed objective lens. Manually coarsely adjust the Z position of the sample so that the initial light spot is located at the interface between the quartz glass slide and the glass precursor photoresist. Place the sample to be processed such as Figure 3 The six different three-dimensional structure models shown in the figure were imported into the processing software in sequence, and the processing parameters (single point exposure time: 1000 μs, processing power: 17 mW) were adjusted before processing. In the above processing, the femtosecond laser two-photon polymerization process of the micro-nano three-dimensional glass blank is as follows: Figure 4 shown.

[0111] 3) Development: After processing, remove the sample and place it in an ethanol solution for upside-down development for 20 minutes.

[0112] 4) Low temperature sintering: Figure 5 As shown in the figure, the developed sample is placed in a muffle furnace, and the temperature is raised to 180°C at a heating rate of 2°C / min and kept for 2.5 hours to remove the residual solvent in the structure. Then the temperature is raised to 420°C at a heating rate of 2°C / min and kept for 3 hours to remove the organic matter in the structure. Subsequently, the temperature is raised to 680°C at a heating rate of 2°C / min and kept for 6 hours. Finally, it is naturally cooled to room temperature to obtain a transparent micro-nano glass three-dimensional structure.

[0113] Characterization was performed with reference to Example 1, and the results were consistent with those of Example 1.

[0114] Example 3

[0115] 1) Configuration materials: such as Figure 1As shown in Figure 2, 1 g of a solution containing methacrylic acid-modified silica nanoparticles (mass fraction of methacrylic acid-modified silica nanoparticles: 40%; solvent: propylene glycol methyl ether) was oscillated and mixed with 20 mg of tetraethyl Michler's ketone (photoinitiator), and ultrasonicated until the tetraethyl Michler's ketone was completely dissolved. The resulting solution was then baked in an oven at 60°C for 18 h to reduce the solvent content in the solution.

[0116] 2) Femtosecond laser two-photon polymerization:

[0117] a. Glue coating: Use a pipette to drop 10 µL of glass precursor photoresist onto a quartz glass slide;

[0118] b. Glue baking: Place the slide on a hot plate at 100°C for 100 seconds;

[0119] c. Processing: Use Figure 2 The femtosecond laser two-photon polymerization processing system is used. The baked glass slide is placed on the Z-axis piezoelectric stage as a sample and fixed, with the glass slide facing the oil-immersed objective lens side. The femtosecond laser is emitted by a titanium sapphire laser, and is incident on the scanning galvanometer after passing through a half-wave plate, a polarization beam splitter, and a beam expander. The scanning galvanometer controls the reflection angle of the reflector to achieve the deflection of the laser beam and complete the movement of the laser in the XY two-dimensional plane. After the laser is emitted from the scanning galvanometer, it passes through the 4f lens group and the reflector and enters the oil-immersed objective lens (60×, 1.4 NA). The laser beam is focused inside the glass precursor photoresist through the oil-immersed objective lens. Manually coarsely adjust the Z position of the sample so that the initial light spot is located at the interface between the quartz glass slide and the glass precursor photoresist. Place the sample to be processed such as Figure 3 The six different three-dimensional structure models shown were imported into the processing software in sequence, and the processing parameters (single point exposure time: 600 μs, processing power: 23 mW) were adjusted before processing. In the above processing, the femtosecond laser two-photon polymerization process of the micro-nano three-dimensional glass green body is as follows Figure 4 shown.

[0120] 3) Development: After processing, remove the sample and place it in an ethanol solution for upside-down development for 40 minutes.

[0121] 4) Low temperature sintering: Figure 5 As shown in the figure, the developed sample is placed in a muffle furnace, and the temperature is raised to 220℃ at a heating rate of 1.5℃ / min and kept for 3 hours to remove the residual solvent in the structure. Then the temperature is raised to 450℃ at a heating rate of 1.5℃ / min and kept for 3 hours to remove the organic matter in the structure. Subsequently, the temperature is raised to 700℃ at a heating rate of 1.5℃ / min and kept for 8 hours. Finally, it is naturally cooled to room temperature to obtain a transparent micro-nano glass three-dimensional structure.

[0122] Characterization was performed with reference to Example 1, and the results were consistent with those of Example 1.

[0123] The above description of the disclosed embodiments will enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is to be construed in the widest manner consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a three-dimensional micro-nano transparent glass structure, characterized in that: The following steps are involved: S1: mixing a solution of silica nanoparticles modified with a photoresponsive ligand and a photoinitiator, and drying the mixture to obtain a glass precursor photoresist; The photoresponsive ligand includes any one or more of methacrylic acid, methacryloxytrimethoxysilane or styryltriethoxysilane; S2: Laser processing a glass slide loaded with a glass precursor photoresist to obtain a micro-nano three-dimensional glass green body, which is then sintered and cooled to obtain a micro-nano transparent glass three-dimensional structure; The sintering temperature does not exceed 700°C.

2. The preparation method according to claim 1, characterized in that The laser processing is femtosecond laser processing; The laser exposure time in the laser processing is 400-1000 μs, and the power is 11-29 mW.

3. The preparation method according to claim 1 or 2, characterized in that The sintering is carried out according to the following procedure: Heat to 160-240°C and keep warm for 2-3 hours; Heat to 400-450°C and keep warm for 3-4 hours; Heat to 650~700℃ and keep warm for 5~10 hours.

4. The preparation method according to claim 1, characterized in that The heating rate during sintering is 1-3°C / min.

5. The preparation method according to claim 1, characterized in that The mass fraction of the solute in the photoresponsive ligand-modified silica nanoparticle solution is 30-60%; The particle size of the silicon dioxide nanoparticles is 15 to 30 nm; The solvent in the photoresponsive ligand-modified silica nanoparticle solution includes any one or more of propylene glycol methyl ether, ethanol, isopropanol, n-butanol, ethylene glycol or propylene glycol; The photoinitiator includes any one or more of tetraethyl Michler's ketone, phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide, or 7-diethylamino-3-thenoylcoumarin.

6. The preparation method according to claim 1, characterized in that The mass ratio of the photoresponsive ligand to the silica nanoparticles is 22:78 to 18:82; The mass ratio of the photoresponsive ligand-modified silica nanoparticles to the photoinitiator is 20:(0.5-1.5).

7. The preparation method according to claim 1, characterized in that The mixing is performed until the photoinitiator is completely dissolved; The drying temperature is 50-80° C. and the drying time is 10-30 h.

8. The preparation method according to claim 1, characterized in that The micro-nano three-dimensional glass green body is developed and then sintered; The development was performed in an ethanol solution.

9. The micro-nano transparent glass three-dimensional structure prepared by the preparation method according to any one of claims 1 to 8, characterized in that: The shrinkage rate of the three-dimensional structure of the micro-nano transparent glass is less than 5%.

10. Use of the micro-nano transparent glass three-dimensional structure prepared by the preparation method according to any one of claims 1 to 8 in the preparation of optical fiber integrated devices.

Images