Silicon dioxide and titanium dioxide hybridized inverse opal structure film and preparation method thereof

Abstract

The invention discloses a silicon dioxide and titanium dioxide hybridized inverse opal structure film and a preparation method thereof. The preparation method comprises the following steps: (1) preparing a silicon dioxide precursor solution, a titanium dioxide precursor solution and a polystyrene nano-microsphere turbid liquid; (2) uniformly mixing the solution obtained in the step (1), and performing ultrasonic treatment to obtain a mixed solution; (3) vertically inserting pretreated hydrophilic glass substrates into the mixed solution in the step (2) at equal intervals, taking out the hydrophilic glass substrates, drying the hydrophilic glass substrates, and carrying out crystal self-assembly growth to obtain a glass slide of which the surface is attached with a polystyrene colloidal crystal and a silicon dioxide and titanium dioxide hybrid inverse opal skeleton structure composite film; and (4) calcining the glass slide with the composite film attached on the surface in the step (3) to obtain the silicon dioxide and titanium dioxide hybridized inverse opal structure film. The prepared inverse opal structure film is uniform in pore, communicated in structure, high in structural integrity and good in light interference signal.

Description

Technical Field

[0001] The invention relates to a preparation method of a colloidal crystal film, in particular to a silicon dioxide and titanium dioxide hybrid inverse opal structure film and a preparation method thereof. Background Art

[0002] Inverse opal film is an ordered porous film obtained by reverse replication of colloidal crystal templates. It also has unique optical properties; but compared with colloidal crystal films, it has a higher specific surface area and space utilization rate, and it shows extremely high freedom in pore size and skeleton materials. Common inverse opal films include polymer inverse opal films, metal oxide inverse opal films, etc.

[0003] The most common method for preparing inverse opal thin films is the sacrificial template method. However, traditional infiltration methods have common drawbacks. For example, the polymer viscosity affects the infiltration process, leading to uneven filling of the template molecular gaps, structural deformation, and ultimately structural cracking and collapse. Uneven infiltration occurs due to changes in the concentration of the precursor solution filling the gaps, and high capillary forces during shrinkage during drying often cause structural fractures. Furthermore, hydrofluoric acid etching is often used to remove the polymer template, which has negative impacts on environmental and human safety.

[0004] The composition of inverse opals affects their optical properties and can further improve their mechanical and optical properties. For optics, the refractive index of the material, the refractive index contrast between the inverse opal matrix and the medium in the pores, and the periodicity of the structure all play an important role in determining the spectral position and intensity of the Bragg resonance. Silica is often used to make highly ordered structures. However, silica has a low refractive index (refractive index of 1.4). When a high refractive index medium or a medium with a refractive index close to it, such as water (refractive index of 1.33), penetrates the pores, the interference peak is lost due to the similar refractive index, which limits the use of silica inverse opal films in any environment other than air (refractive index of 1). The weak mechanical properties of the titanium dioxide inverse opal structure often bring additional difficulties to ordered manufacturing at the micron scale. Summary of the Invention

[0005] Purpose of the invention: In order to overcome the deficiencies in the prior art, the present invention aims to provide a method for preparing a silicon dioxide and titanium dioxide hybrid inverse opal structure film with good operability and stability; another purpose of the present invention is to provide a silicon dioxide and titanium dioxide hybrid inverse opal structure film with uniform pores, structural connectivity, high structural integrity and good optical interference signal.

[0006] Technical solution: The method for preparing the inverse opal structure thin film hybridized with silicon dioxide and titanium dioxide of the present invention comprises the following steps:

[0007] (1) Tetraethyl orthosilicate, anhydrous ethanol and dilute hydrochloric acid are mixed and stirred to obtain a silicon dioxide precursor solution; di(2-hydroxypropionic acid) diammonium dihydroxide titanium is mixed with hydrochloric acid and stirred to obtain a titanium dioxide precursor solution; polystyrene nanospheres are mixed with deionized water, ultrasonically treated, centrifuged and the supernatant is removed, deionized water is added to the precipitate, ultrasonically dispersed, and the ultrasonic and centrifugal treatments are repeated to obtain a polystyrene nanosphere suspension;

[0008] (2) uniformly mixing the silica precursor solution, the titanium dioxide precursor solution and the polystyrene nanosphere suspension, and ultrasonically treating the mixture to obtain a mixed solution;

[0009] (3) inserting the pre-treated hydrophilized glass substrate vertically into the mixed solution of step (2), taking it out and drying it, and performing crystal self-assembly growth to obtain a glass slide with a polystyrene colloidal crystal and a composite film of an inverse opal skeleton structure hybridized with silicon dioxide and titanium dioxide attached to the surface;

[0010] (4) calcining the glass slide with the composite film attached to the surface in step (3) to obtain an inverse opal structure film hybridized with silicon dioxide and titanium dioxide.

[0011] Furthermore, in step (1), the mass percentage of tetraethyl orthosilicate is 0.25-0.35 wt%, and the volume ratio of tetraethyl orthosilicate, anhydrous ethanol and dilute hydrochloric acid is 2-3:3:2.

[0012] Furthermore, in step (1), the mass percentage of bis(2-hydroxypropionic acid)diammonium titanium dihydroxide is 0.12-0.14 wt %, and the volume ratio of bis(2-hydroxypropionic acid)diammonium titanium dihydroxide to dilute hydrochloric acid is 1:6-7.

[0013] Furthermore, in step (1), the particle size of the polystyrene nanospheres is 300-700 nm, and the mass percentage of the polystyrene nanosphere suspension is 0.25-0.75 wt %.

[0014] Furthermore, in step (1), the ultrasonic treatment time is 20 to 30 minutes, the ultrasonic frequency is 20 to 60 kHz, the centrifugal treatment speed is 8000 to 10000 rpm, and the centrifugal treatment time is 25 to 30 minutes.

[0015] Furthermore, in step (2), the volume ratio of the polystyrene nanosphere suspension, the silica precursor solution and the titanium dioxide precursor solution is 50-200:1:1, the ultrasonic treatment time is 20-30 min, and the ultrasonic frequency is 20-60 kHz.

[0016] Furthermore, in step (3), the pretreatment is to soak the hydrophilized glass substrate in piranha wash solution for 18 to 24 hours, wash it, and dry it at 60 to 65 degrees Celsius for 3 to 5 hours; after closely fitting two hydrophilized glass substrates together, the substrates are vertically inserted into the mixed solution of step (2) at equal distances and fixed on a container. The purpose of closely fitting the two substrates together is to grow a crystal film only on one side of the glass slide; growing a crystal film on both sides of the glass substrate will affect the collection of the reflection interference spectrum; fixing the glass substrate on the container can reduce vibration and avoid affecting the growth of the crystal.

[0017] Furthermore, in step (3), the growth temperature of the crystal self-assembly is 60-65° C., and the growth time is 18-24 h.

[0018] Furthermore, in step (4), the calcination temperature is 450-550° C. and the calcination time is 2-2.5 hours to remove the polystyrene nanospheres.

[0019] The film prepared by the method for preparing the hybrid inverse opal structure film of silicon dioxide and titanium dioxide according to the present invention has uniform pores and a connected structure, and the pore size is 100 to 500 nm.

[0020] Preparation Principle: The preparation method described herein involves pre-hydrolyzing silica and titania precursors in separate hydrolysis solutions to prepare hybrid silica-titania samples. These samples are then combined with a polymer colloid in a suspension and subjected to nanoscale self-assembly on a substrate using solvent-induced evaporation. During the self-assembly process, polystyrene (PS) colloid particles in a suspension of PS nanospheres in a wetting gap on a glass substrate are gradually anchored to the substrate by capillary forces at the contact line, starting at the edge of the meniscus. The slow upward motion of the substrate plane initially induces a tapering meniscus curvature at the leading edge of the anchored PS microsphere array. This dynamic change triggers subsequent protruding PS microspheres to form an ordered assembly structure through capillary forces with the pre-anchored leading PS microsphere array along the boundary region. During this process, the dissolved silica and titania precursors construct a molecular bridging network between adjacent PS microspheres, resulting in a gradient dissipation effect of interparticle forces, thereby optimizing the colloidal self-assembly kinetics. These bridging molecules are stably present in the contact interface neighborhoods of PS microspheres in the opal structure, inducing the formation of a stable physical cross-linking network between the microspheres.

[0021] Beneficial effects: Compared with the prior art, the present invention has the following significant features:

[0022] 1. Compared with traditional infiltration methods, the sol-gel co-growth method avoids film cracks and even structural collapse caused by the viscosity, infiltration rate, and capillary tension of the filler during drying. The prepared inverse opal structure film has high structural integrity and good optical interference signal;

[0023] 2. Compared with the traditional sacrificial template method, the sol-gel co-growth method has better operability and stability, the obtained film has excellent mechanical properties, and can construct a three-dimensional ordered film structure;

[0024] 3. By adjusting the silica-titanium dioxide doping ratio, the refractive index of the inverse opal structure film can be adjusted, thereby adjusting the intensity of the interference peak to meet the requirements of interference spectrum collection in the aqueous phase;

[0025] 4. The thickness of the inverse opal structure film can be precisely controlled by adjusting the concentration of polystyrene microspheres, thereby adjusting the number of interference peaks;

[0026] 5. The product inverse opal structure film has uniform pores, connected structure, stable white light interference performance, and can be stably produced in batches. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the preparation method of the present invention;

[0028] Figure 2 1 is a scanning electron microscope image of the polystyrene opal structure film prepared in Example 1 of the present invention, wherein (A) is a top view, (B) is a side view, and (c) is a top view of the inverse opal structure film after calcination;

[0029] Figure 3 are interference spectra of the silica-titania hybrid inverse opal structure films prepared in Examples 1 to 5 of the present invention, wherein (A) the pore medium is air and (B) the pore medium is water;

[0030] Figure 4 3 are scanning electron micrographs of the silicon dioxide-titania hybrid inverse opal structure film prepared in Example 3 of the present invention, wherein (A) is magnified 2000 times and (B) is magnified 30,000 times;

[0031] Figure 5 is the interference spectrum of the inverse opal structure film with a silicon dioxide-titanium dioxide hybrid ratio of 1:1 prepared in Example 1 of the present invention;

[0032] Figure 6 This is the interference spectrum of the inverse opal structure film with a silica-titania hybrid ratio of 3:1 prepared in Comparative Example 1;

[0033] Figure 7 is the interference spectrum of the inverse opal structure film with a silica-titania hybrid ratio of 1:3 prepared in Comparative Example 2;

[0034] Figure 8 is the interference spectrum of the silicon dioxide inverse opal structure film prepared in Comparative Example 3;

[0035] Figure 9 This is the interference spectrum of the titanium dioxide hybrid inverse opal structure film prepared in Comparative Example 4. DETAILED DESCRIPTION

[0036] The present invention is further described below with reference to specific embodiments.

[0037] Slide (76×26×1mm 3 ) was used as a substrate for the growth of colloidal crystal films. Colored monodisperse polystyrene nanospheres (2.5 wt%, particle sizes of 100 nm, 300 nm, 500 nm, and 700 nm) were purchased from Shanghai Yuanfan Biotechnology Co., Ltd. Anhydrous ethanol, tetraethyl orthosilicate (C8H 20 O4Si, >99% (GC)) was purchased from Shanghai Boer Chemical Reagent Co., Ltd., and di(2-hydroxypropionic acid) diammonium dihydroxide titanium (C6H 18 N₂O₂Ti (50 wt%) was purchased from Nanjing Wanqing Chemical Instrument Co., Ltd., and anhydrous ethanol was purchased from Nanjing Maibo Chemical Reagent Co., Ltd. All reagents except for silica nanospheres and colored monodisperse polystyrene nanospheres were used without further treatment. All experimental water was obtained from a Millipore water purifier (Millipore, resistivity ≥ 18 MΩ·cm).

[0038] Example 1

[0039] A method for preparing a silicon dioxide and titanium dioxide hybrid inverse opal structure film, such as Figure 1 As shown, the following steps are included:

[0040] (1) Soak the glass substrate in piranha solution for 24 h, take it out and wash it with ultrapure water to remove impurities on the glass substrate, and then dry it in an oven at 65°C for 3 h.

[0041] (2) Tetraethyl orthosilicate, anhydrous ethanol, and 0.1 M hydrochloric acid were mixed in a volume ratio of 2:3:2, and magnetically stirred for 1 hour to obtain a silica precursor solution. The mass percentage of tetraethyl orthosilicate was 0.25 wt%.

[0042] (3) Titanium bis(2-hydroxypropionic acid) diammonium dihydroxide and 0.1 M hydrochloric acid were mixed in a volume ratio of 1:6 and magnetically stirred for 1 hour to obtain a titanium dioxide precursor solution. The mass percentage of titanium bis(2-hydroxypropionic acid) diammonium dihydroxide was 0.12 wt%.

[0043] (4) Washing the polystyrene nanospheres: Mix polystyrene nanospheres with an average particle size of 300 nm with deionized water and thoroughly mix them in an ultrasonic cleaner for 20 minutes. Centrifuge the mixture at 10,000 rpm for 25 minutes in a high-speed refrigerated centrifuge, remove the supernatant, add deionized water to the retained precipitate, and ultrasonically disperse it in an ultrasonic cleaner for 30 minutes. Repeat this process three times to obtain a 0.25 wt% polystyrene nanosphere suspension.

[0044] (5) The polystyrene nanosphere suspension, silica precursor solution, and titanium dioxide precursor solution were mixed at a volume ratio of 200:1:1, and the mixed solution was placed in an ultrasonic cleaner for 20 minutes to mix evenly.

[0045] (6) After two pretreated glass slides are tightly fitted together, they are vertically inserted into the prepared mixed solution at equal distances, and the glass slides are firmly fixed on the container. The glass slides are taken out and dried at 65°C for 2 to 4 hours, and placed in a crystal incubator at 65°C for 24 hours to obtain glass slides with polystyrene colloidal crystals and a composite film of an inverse opal skeleton structure hybridized with silicon dioxide and titanium dioxide attached to the surface.

[0046] (7) The glass slide was taken out and placed in a 500° C. program-controlled electric furnace for calcination for 2 hours to remove the polystyrene nanospheres, thereby obtaining a silicon dioxide and titanium dioxide hybrid inverse opal structure film.

[0047] like Figure 2 As shown, the scanning electron microscope image of the prepared polystyrene opal structure template film is shown. Figure 2 (A) is a top view, Figure 2 (B) is a side view, Figure 2 (C) is a top view of the inverse opal structure film after calcination. Polystyrene is orderly and densely packed over a large area on the glass slide, showing a typical colloidal crystal structure. In addition, the precursor solutions of silica and titania do not destroy the regularity of the structure of the polystyrene colloidal crystal film.

[0048] Example 2

[0049] The remaining steps of this embodiment are the same as those of embodiment 1, with the only difference being that the concentration of the polystyrene microsphere suspension in step (4) is 0.375 wt%.

[0050] Example 3

[0051] The remaining steps of this embodiment are the same as those of embodiment 1, with the only difference being that the concentration of the polystyrene microsphere suspension in step (4) is 0.5 wt %.

[0052] Example 4

[0053] The remaining steps of this embodiment are the same as those of embodiment 1, with the only difference being that the concentration of the polystyrene microsphere suspension in step (4) is 0.625 wt%.

[0054] Example 5

[0055] The remaining steps of this embodiment are the same as those of embodiment 1, with the only difference being that the concentration of the polystyrene microsphere suspension in step (4) is 0.75 wt %.

[0056] like Figure 3 As shown in Figure 2, the interference spectra of the inverse opal structure films of different thicknesses of silicon dioxide and titanium dioxide hybrids prepared by using polystyrene microspheres in a concentration range of 0.25 to 0.75 wt % in Examples 1 to 5, wherein: Figure 3 (A) is the interference spectrum when the pore filling medium is air, Figure 3 (B) is the interference spectrum when the porous medium is water. Figure 3 As shown in (A), as the concentration of polystyrene microspheres increases, the number of interference peaks gradually increases. When the concentration is between 0.375wt% and 0.5wt%, better interference fringes are produced, with a larger number of fringes and higher intensity. The change in the number of fringes and their intensity due to the increase in thickness is due to the increase in the amount of reflected light in the hole and the simultaneous decrease in light intensity controlled by multiple reflections of light. Figure 3 As shown in (B), compared to the interference pattern in air, all samples exhibit a characteristic redshift and intensity attenuation after water infiltration due to the change in the pore-filling medium and the resulting refractive index change, consistent with the expected refractive index change. When the medium is water, there is a loss in the number of interference peaks compared to the air interference spectrum. This is due to the increasing refractive index of the medium, which gradually approaches that of the film. When the concentration is less than 0.375wt%, the number of interference peaks in the water phase decreases, posing a challenge to the stability of the optical interference signal. When the concentration is greater than 0.5wt%, the interference peak intensity is lost, which is also detrimental to interference signal acquisition.

[0057] like Figure 4 As shown in Example 3, the concentration of the polystyrene microsphere suspension is 0.5wt%, and the hybrid ratio of silicon dioxide and titanium dioxide is 1:1. The scanning electron microscope image of the inverse opal structure film is shown in FIG. Figure 4 (A) is magnified 2000 times. Figure 4 (B) is a 30,000x magnification. The interconnectedness of the ordered porous structure of the prepared inverse opal film can be clearly observed. The structure of the hybrid inverse opal film made of silica and titania is orderly, with uniform pores (average pore size of 300 nm). The pores are interconnected, avoiding the structural cracks and local collapse caused by the mechanical deficiencies of titania.

[0058] like Figure 5 Figure 2 shows the interference spectra of the silicon dioxide and titanium dioxide hybrid inverse opal structure film prepared in Example 1 in air and water. When the pore-filling medium is air with a refractive index of 1, regular interference peak signals are detected. When the pore-filling medium is water with a refractive index of 1.33, interference peak signals with higher peak intensity are detected, indicating that the addition of titanium dioxide significantly increases the refractive index of the film.

[0059] Among the above embodiments, embodiment 3 is the best embodiment.

[0060] Comparative Example 1

[0061] The remaining steps of this embodiment are the same as those of embodiment 1, with the only difference being that the volume ratio of the polystyrene nanosphere suspension, the silicon dioxide precursor solution, and the titanium dioxide precursor solution in step (5) is 200:3:1. Figure 6 As shown in the figure, the interference spectra of the prepared silica and titania hybrid inverse opal structure film in air and water, when the pore filling medium is air with a refractive index of 1, regular interference peak signals can be collected, when the pore medium is water with a refractive index of 1.33, interference peak signals with lower peak intensity can be collected.

[0062] Comparative Example 2

[0063] The remaining steps of this embodiment are the same as those of embodiment 1, with the only difference being that the volume ratio of the polystyrene nanosphere suspension, the silicon dioxide precursor solution, and the titanium dioxide precursor solution in step (5) is 200:1:3. Figure 7 As shown in the figure, the interference spectra of the prepared silica and titania hybrid inverse opal structure film in air and water, when the pore filling medium is air with a refractive index of 1, regular interference peak signals can be collected, when the pore medium is water with a refractive index of 1.33, interference peak signals with higher peak intensity can be collected, but the addition of too much titania leads to a decrease in the number of interference peaks of the film. This is because too much titania leads to insufficient mechanical properties of the film, resulting in cracks and collapse of the film.

[0064] Comparative Example 3

[0065] The difference from Example 1 is that the volume ratio of the polystyrene nanosphere suspension, the silicon dioxide precursor solution, and the titanium dioxide precursor solution in step (5) is 200:1:0. Figure 8 As shown in the figure, the interference spectra of the prepared silica hybrid inverse opal structure film in air and water, when the pore filling medium is air with a refractive index of 1, regular interference peak signals can be collected. When the pore medium is water with a refractive index of 1.33, no interference peak signals can be collected because the refractive index is close to that of the silica substrate of the film.

[0066] Comparative Example 4

[0067] The difference from Example 1 is that the volume ratio of the polystyrene nanosphere suspension, the silicon dioxide precursor solution, and the titanium dioxide precursor solution in step (5) is 200:0:1. Figure 9 As shown in the interference spectra of the prepared titanium dioxide hybrid inverse opal structure film in air and water, no interference peak signal can be collected when the pore filling medium is air with a refractive index of 1 and water with a refractive index of 1.33. This is because the mechanical properties of the film are insufficient due to pure titanium dioxide, making it difficult to construct a three-dimensional ordered film structure.

Claims

1. A method for preparing a silicon dioxide and titanium dioxide hybrid inverse opal structure film, characterized in that: The following steps are involved: (1) Tetraethyl orthosilicate, anhydrous ethanol and dilute hydrochloric acid are mixed and stirred to obtain a silicon dioxide precursor solution; di(2-hydroxypropionic acid) diammonium dihydroxide titanium is mixed with hydrochloric acid and stirred to obtain a titanium dioxide precursor solution; polystyrene nanospheres are mixed with deionized water, ultrasonically treated, centrifuged and the supernatant is removed, deionized water is added to the precipitate, ultrasonically dispersed, and the ultrasonic and centrifugal treatments are repeated to obtain a polystyrene nanosphere suspension; (2) uniformly mixing the silica precursor solution, the titanium dioxide precursor solution and the polystyrene nanosphere suspension, and ultrasonically treating the mixture to obtain a mixed solution; (3) inserting the pre-treated hydrophilized glass substrate vertically into the mixed solution of step (2), taking it out and drying it, and performing crystal self-assembly growth to obtain a glass slide with a polystyrene colloidal crystal and a composite film of an inverse opal skeleton structure hybridized with silicon dioxide and titanium dioxide attached to the surface; (4) calcining the glass slide with the composite film attached to the surface in step (3) to obtain an inverse opal structure film hybridized with silicon dioxide and titanium dioxide.

2. The method for preparing a hybrid inverse opal structure thin film of silicon dioxide and titanium dioxide according to claim 1, wherein: In the step (1), the mass percentage of tetraethyl orthosilicate is 0.25-0.35 wt %, and the volume ratio of tetraethyl orthosilicate, anhydrous ethanol and dilute hydrochloric acid is 2-3:3:

2.

3. The method for preparing a hybrid inverse opal structure thin film of silicon dioxide and titanium dioxide according to claim 1, wherein: In the step (1), the mass percentage of bis(2-hydroxypropionic acid)diammonium titanium dihydroxide is 0.12-0.14 wt %, and the volume ratio of bis(2-hydroxypropionic acid)diammonium titanium dihydroxide to dilute hydrochloric acid is 1:6-7.

4. The method for preparing a hybrid inverse opal structure thin film of silicon dioxide and titanium dioxide according to claim 1, wherein: In the step (1), the particle size of the polystyrene nanospheres is 300-700 nm, and the mass percentage of the polystyrene nanosphere suspension is 0.25-0.75 wt %.

5. The method for preparing a hybrid inverse opal structure thin film of silicon dioxide and titanium dioxide according to claim 1, characterized in that: In the step (1), the ultrasonic treatment time is 20 to 30 minutes, the ultrasonic frequency is 20 to 60 kHz, the centrifugal treatment speed is 8000 to 10000 rpm, and the centrifugal treatment time is 25 to 30 minutes.

6. The method for preparing a hybrid inverse opal structure thin film of silicon dioxide and titanium dioxide according to claim 1, characterized in that: In the step (2), the volume ratio of the polystyrene nanosphere suspension, the silicon dioxide precursor solution and the titanium dioxide precursor solution is 50-200:1:1, the ultrasonic treatment time is 20-30 minutes, and the ultrasonic frequency is 20-60 kHz.

7. The method for preparing a hybrid inverse opal structure thin film of silicon dioxide and titanium dioxide according to claim 1, characterized in that: In the step (3), the pretreatment is to soak the hydrophilized glass substrates in piranha lotion for 18 to 24 hours, wash them, and dry them at 60 to 65° C. for 3 to 5 hours; and then, after closely fitting two hydrophilized glass substrates together, vertically insert them into the mixed solution of step (2) at equal distances and fix them on the container.

8. The method for preparing a silicon dioxide and titanium dioxide hybrid inverse opal structure film according to claim 1, characterized in that: In the step (3), the growth temperature of the crystal self-assembly is 60-65° C., and the growth time is 18-24 hours.

9. The method for preparing a silicon dioxide and titanium dioxide hybrid inverse opal structure thin film according to claim 1, characterized in that: In the step (4), the calcination temperature is 450-550° C., and the calcination time is 2-2.5 hours.

10. The silicon dioxide and titanium dioxide hybrid inverse opal structure thin film obtained by the method for preparing the silicon dioxide and titanium dioxide hybrid inverse opal structure thin film according to any one of claims 1 to 9, characterized in that: The pores of the film are uniform and connected, with a pore size of 100 to 500 nm.

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