Photonic crystal colloid film based on PVP modification and preparation method thereof

Abstract

The invention discloses a photonic crystal colloid film based on polyvinylpyrrolidone (PVP) modification and a preparation method of the photonic crystal colloid film. The photonic crystal colloid film is formed by self-assembling silicon dioxide microspheres (SiO2) subjected to PVP surface modification in an elastic colloid with polyethylene glycol phenyl ether acrylate (PEGPEA) and diethylene glycol ethyl ether acrylate (DEGEEA) as main components and performing ultraviolet curing through a photoinitiator 1173. Compared with a traditional photonic crystal thin film, the photonic crystal colloid thin film effectively inhibits angle dependence, and stable characterization of the photonic crystal structural color is achieved. Meanwhile, the film has the characteristics of good flexibility, high sensitivity, environmental friendliness and simple process, shows extremely high production efficiency in large-scale industrial production, and has remarkable technical advantages and application potential.

Description

Technical Field

[0001] The invention relates to the field of photonic crystal films, and in particular to a method for preparing a photonic crystal colloidal film based on PVP modification and using ultraviolet curing technology. Background Art

[0002] The molecular structure of PVP contains a highly polar lactam hydrophilic group and a CC long-chain lipophilic group. This amphiphilic structure makes it compatible with a variety of solvents and can be coated on the surface of particles through steric hindrance to achieve modification. Especially for micro-nano particles such as carbon nanotubes, MoS2 nanosheets and SiO2 microspheres, which have small particle sizes and large specific surface areas and are difficult to disperse evenly during the homogenization process, PVP is widely used and has significant effects.

[0003] With the advantages of liquid-solid conversion, UV curing technology has shown broad application prospects in the fields of electronic packaging, printed circuit board PCB manufacturing, micro-optical electromechanical and biochip processing, optical component preparation, etc. UV-cured photonic crystal colloidal films have attracted widespread attention due to their high efficiency, low cost, plasticity, and stretchability.

[0004] The photonic crystal colloidal film based on UV curing is composed of two parts: photonic crystal and elastic colloid. For example, the photonic crystal with microspheres of uniform particle size as the main component self-assembles into a microsphere array inside the elastic colloid, so that the film presents structural color and has the performance of stretching color change. In recent years, SiO2 microspheres are often used as photonic crystals, and acrylate is directly mixed and prepared as elastic colloid. However, the surface of SiO2 microspheres without surface modification is hydrophobic and easy to crystallize and agglomerate, resulting in a decrease in the structural color characterization performance of the entire photonic crystal colloidal film; at the same time, pure acrylate is usually viscous and difficult to fully mix with photonic crystals and penetrate into a certain thickness of glass interlayer, which makes it difficult to prepare a photonic crystal colloidal film of a given thickness, affecting the film performance and processing efficiency. If the spin coating method is used, although the thickness parameters under certain process conditions can be obtained through the experimental data curve, it will affect the uniform characterization of the structural color of the photonic crystal colloidal film and cause serious waste of photonic crystal colloid.

[0005] It is worth noting that the preparation of photonic colloid is an important step in the preparation of photonic crystal colloidal film, and its purpose is to mix the set photonic crystal with the elastic colloid. Therefore, as long as a high-fluidity liquid environment is provided, the two parts can be fully mixed and infiltrated into the glass interlayer, ensuring the stable characterization of the structural color and thickness of the photonic crystal colloidal film. Based on the above analysis, the present invention proposes a method for preparing a photonic crystal colloidal film with low angle dependence and uniform color by using PVP modified SiO2 microspheres. Summary of the invention

[0006] The present invention aims to provide a photonic crystal colloidal film based on PVP modification and a preparation method thereof, and achieves low angle dependence and uniform structural color characterization of the photonic crystal colloidal film through UV curing technology, and solves the problem that the film thickness design is difficult due to insufficient fluidity of the photonic colloid. The specific steps are as follows:

[0007] The technical solution of the present invention to solve the above technical problems is as follows:

[0008] First, a photonic crystal colloidal film based on PVP modification and a preparation method thereof, the basic materials and equipment involved include: SiO2 microspheres with uniform particle size, PVP, PEGPEA, DEGEEA, photoinitiator 1173, TEOS, ammonia water, centrifuge tubes, measuring cylinders, heating rods, balances, pipettes, convection drying ovens, beakers, magnets, magnetic stirrers, brown narrow-necked bottles, deionized water, ethanol, acetone, ultrasonic cleaners, plasma cleaners, glass sheets, capillary glass rods, insulators and mercury lamp ultraviolet light sources. The SiO2 microspheres and PVP are used to form the photonic crystal part. After mixing, the PVP modifies the surface of the SiO2 microspheres to prevent excessive crystallization. The PEGPEA and DEGEEA are used to form the elastic colloid part. After mixing, the photonic colloid obtained has strong fluidity and is easy to penetrate into the glass interlayer. The photoinitiator 1173 can induce the photonic crystal colloid to undergo monomer polymerization, cross-linking and curing reaction under ultraviolet light. The TEOS, ammonia water, centrifuge tube, measuring cylinder, beaker, magnet, magnetic stirrer, heating rod and convection drying oven are used to prepare the photonic crystal colloid. The method comprises the following steps: preparing SiO2 microsphere solid powder by a method; the balance is used to weigh a certain amount of SiO2 microsphere solid powder and PVP solid powder to be prepared; the pipette is used to mix the ethanol mixture of different components according to a set ratio; the convection drying oven is used to evaporate ethanol; the beaker is used for preliminary mixing and stirring and the first stage of evaporation; the brown narrow-necked bottle is used for the second stage of evaporation and the long-term storage of photonic colloid; the ultrasonic cleaning machine, deionized water, ethanol, acetone and plasma cleaning machine are used to clean glass slides to improve the hydrophilicity of the glass slide surface, and in particular, ethanol is also used to provide a liquid environment for fully mixing the photonic crystal and the elastic colloid; the glass slide, capillary glass rod and insulator are used to construct a glass slide interlayer of a certain thickness; the mercury lamp ultraviolet light source is used to excite the monomer polymerization, cross-linking and curing reaction of the photonic crystal colloid, so that the photonic crystal is encapsulated inside the colloidal film, the structural color of the film is stably characterized, and the film is endowed with the property of tensile color change.

[0009] Secondly, a photonic crystal colloidal film based on PVP modification and a preparation method thereof, comprising the following steps:

[0010] S1: Pass Method for preparing monodisperse SiO2 microsphere particles;

[0011] S2: Mix PEGPEA ethanol mixed solution, DEGEEA ethanol mixed solution, SiO2 ethanol suspension, and PVP ethanol mixed solution in a beaker, add a photoinitiator, and finally perform magnetic stirring to obtain a photon colloid ethanol mixed solution to be evaporated;

[0012] S3: In a convection drying oven, the first stage of ethanol evaporation is carried out in a beaker, and then the ethanol is transferred to a brown narrow-necked bottle for the second stage of ethanol evaporation to obtain photon colloid;

[0013] S4: Sprinkle spacers on a glass slide using a capillary glass tube, cover it with another glass slide, and then infiltrate the photon colloid into the glass slide interlayer, and then let it stand in a light-proof condition;

[0014] S5: placing the photonic colloid to be solidified under an ultraviolet light source, irradiating the front and back sides for a certain period of time, and then peeling off to obtain a photonic crystal colloid film.

[0015] In the step S1, The steps for preparing SiO2 microspheres by the method are as follows: first, prepare 3mL of TEOS and 2mL of ethanol mixture in a centrifuge tube and fully blend them by ultrasound; then, pour 48mL of ethanol into a 100mL beaker and drop 3.1mL-3.3mL of ammonia water, put in a magnetic bar for low-speed stirring, and heat in a 34°C water bath under a heating rod. After about 0.5h, drop the TEOS ethanol mixture and react. After about 5h, a milky white liquid is obtained; the beaker is placed in a convection drying oven to volatilize the ethanol, and finally a solid powder of SiO2 microspheres is obtained.

[0016] In the step S2, 24 mL of the photon colloid ethanol mixture is mixed with 25 wt% SiO2 microsphere ethanol suspension, 25 wt% PVP ethanol mixture, 10 wt% PEGPEA ethanol mixture and 10 wt% DEGEEA ethanol mixture in a ratio of 1:1:3:1, and then 16 μL-48 μL of photoinitiator 1173 is dropped into it, and it is stirred at 250 rpm-350 rpm on a magnetic stirrer; the photoinitiator 1173 accounts for about 1 wt%-3 wt% of the elastic colloid PEGPEA and DEGEEA, and too high or too low a content will affect the completion of the cross-linking polymerization reaction in the subsequent UV curing.

[0017] In the step S3, the drying temperature condition is 60°C to keep the ethanol evaporation rate always controllable; in the first stage, the rapid ethanol evaporation of the photon colloid ethanol mixture is carried out in a beaker, and after about 0.5h-1h, it enters the second stage and is transferred to a brown narrow-necked bottle. After about 8h-12h, the remaining ethanol is completely removed. Since the evaporation rate is slower, excessive volatilization of DEGEEA at high temperature can be avoided as much as possible, thereby ensuring the fluidity of the photon colloid, and the brown narrow-necked bottle is conducive to subsequent long-term storage; finally, a photon colloid with obvious structural color is obtained.

[0018] In step S4, the glass slide interlayer is composed of an upper glass slide, a spacer and a lower glass slide. The photon colloid is injected into the edge of the interlayer using a pipette. After penetrating into the interlayer, it is placed in a light-proof condition and left to stand for 0.5h-1h to release the internal stress generated after the photon colloid is injected into the interlayer.

[0019] In step S5, the UV curing scheme is to irradiate the front and back sides of the photonic colloid in the glass slide interlayer with UV light for about 20s-30s under a UV mercury lamp light source to obtain a cured photonic crystal colloid film; then, one side of the glass slide is directly removed under normal temperature and pressure conditions to peel off and obtain the photonic crystal colloid film.

[0020] Among them, the glass slides used above are ultrasonically cleaned in deionized water, ethanol and acetone in turn, and the ultrasonic cleaning conditions are 5min-10min; the plasma cleaning conditions are 5min, Ar-0.9ccm, O2-200ccm, power 200W-300W; the insulator size is 20μm-80μm, the purpose is to remove impurities on the surface of the glass slide and improve its hydrophilicity.

[0021] The central wavelength of the ultraviolet mercury lamp used above is 365nm, the power is 300W-350W, and the irradiance at the irradiation plane is 15.7mW / cm 2 -18.9mW / cm 2 .

[0022] In the above scheme, the contents of steps S1-S5 are only for more clearly explaining the process flow of preparing the photonic crystal colloidal film with the above characteristics, and are not limitations on the liquid environment, mixing and stirring method, equipment facilities and film shaping method in the above process flow.

[0023] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0024] The present invention can make the photonic crystal colloidal film have the following advantages at the same time:

[0025] (1) The PVP used was used to modify the surface of SiO2 microspheres, ensuring the stable characterization of the structural color of the photonic crystal colloidal film and achieving the characteristics of low angle dependence;

[0026] (2) The unsaturated PEG segments in the PEGPEA and DEGEEA used are conducive to the formation of a uniform network structure of the photonic colloid during the UV curing process, which improves the elastic modulus of the colloidal film and contributes to the tensile discoloration of the photonic crystal colloidal film;

[0027] (3) The colloidal plastic method used is a glass slide sandwich with a certain interval, which ensures the designability of the thickness of the photonic crystal colloidal film. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the structure of the photonic crystal colloidal film modified by PVP according to the present invention.

[0029] Figure 2 In Example 1 of the present invention Scanning electron microscope image of SiO2 microspheres prepared by the method. The average particle size of SiO2 microspheres is 210nm±5nm, and they are arranged in hexagonal close packing to form photonic crystals.

[0030] Figure 3 It is a schematic diagram of the principle of PVP molecules modifying the surface of SiO2 microspheres in the present invention.

[0031] Figure 4 It is an optical photograph of the photonic crystal colloidal film prepared in Examples 1, 2 and 3 of the present invention at an observation angle of 90°, wherein the observation angle refers to the angle between the line of sight and the interface.

[0032] Figure 5 It is the change of chromaticity coordinates of different structural colors produced by photonic crystal colloidal films of different thicknesses prepared in Examples 1, 2 and 3 of the present invention in the CIE 1976 chromaticity diagram.

[0033] Figure 6 These are optical photographs of the photonic crystal colloidal film prepared in Example 1 of the present invention at observation angles of 60° and 30°, where the observation angle refers to the angle between the line of sight and the interface.

[0034] Figure 7 It is the change of chromaticity coordinates of different structural colors produced by the photonic crystal colloidal film prepared in Example 1 of the present invention at different observation angles of 90°, 60° and 30° in the CIE 1976 chromaticity diagram, wherein the observation angle refers to the angle between the line of sight and the interface.

[0035] Figure 8 These are optical photographs of the photonic crystal colloidal film prepared in Example 1 of the present invention at stretching rates of 0%, 50%, 100%, and 120%, respectively.

[0036] Fig. 9 The graph is a variation of the chromaticity coordinates of different structural colors produced by the photonic crystal colloidal film prepared in Example 1 of the present invention at different stretching rates in the CIE 1976 chromaticity diagram.

[0037] Fig.10 This is a curve of the dominant wavelength change of the photonic crystal colloidal film prepared in Example 1 of the present invention at different observation angles, stretching degrees, and different film thicknesses prepared in Examples 1, 2, and 3. DETAILED DESCRIPTION

[0038] To facilitate those skilled in the art to understand the technical content of the present invention, the present invention is further explained below with reference to the accompanying drawings and specific examples.

[0039] Figure 1 Shown is a schematic structural diagram of a PVP-modified photonic crystal colloidal film prepared by the present invention. The preparation method provided by the present invention is described in detail below through specific examples to further demonstrate the advantages of the present invention.

[0040] Example 1

[0041] (1) Preparation of SiO2 microspheres

[0042] ① First, prepare a mixture of 12 mL of TEOS and 8 mL of ethanol in a centrifuge tube, and place it in an ultrasonic machine for about 5 minutes to allow it to fully blend.

[0043] ② Pour 42mL of ethanol into a 100mL beaker and drop 3.1mL-3.3mL of ammonia water into it, put in the magnet cleaned with ethanol, place the beaker into a 1L large beaker, pour in an appropriate amount of deionized water, heat in a 34℃ water bath under a heating rod for about 0.5h, and start magnetic stirring and mixing at a speed of 250rpm-350rpm.

[0044] ③ Add TEOS ethanol mixture twice, half the dose each time, with an interval of 0.5h, to react. After about 5h, a milky white liquid can be obtained; put the beaker into a convection drying oven to evaporate the ethanol, obtain the solid precipitate of SiO2 microspheres, and obtain the solid powder of SiO2 microspheres after sufficient grinding.

[0045] (2) Preparation of photonic colloids

[0046] ① First, use a balance to weigh about 2g of SiO2 microsphere solid powder and PVP powder, put them into a centrifuge tube, and use a pipette to add about 7.64mL of ethanol, then use an ultrasonic machine to fully blend for 5 minutes to obtain 25wt% SiO2 microsphere ethanol suspension and PVP ethanol mixture, recorded as A and B.

[0047] ② Use a pipette to draw about 2 mL of PEGPEA and DEGEEA, put them into a centrifuge tube, add about 22.92 mL of ethanol, and then fully blend them in an ultrasonic machine for 5 minutes to obtain 10 wt% PEGPEA ethanol mixture and DEGEEA ethanol mixture, which are recorded as C and D.

[0048] ③ Prepare the photon colloid ethanol mixture. Use a pipette to keep the scale at a fixed position, and take A, B, C, and D in a ratio of 1:1:3:1 in sequence, and drop them into a 50mL beaker cleaned with ethanol, and finally drop 16μL-48μL of photoinitiator 1173 to obtain about 24mL of photon colloid ethanol mixture; put a magnetic rod cleaned with ethanol in a magnetic stirrer for magnetic stirring at 250rpm-350rpm, and after about 0.5h-1h, take out the magnetic rod to obtain the photon colloid ethanol mixture to be evaporated.

[0049] ④ Evaporating ethanol to obtain photon colloid. The temperature condition of the convection drying oven is set to 60°C; in the first stage, the rapid ethanol evaporation of the photon colloid ethanol mixture is carried out in a beaker, and after about 0.5h-1h, it enters the second stage, and the photon colloid ethanol mixture is transferred to a brown narrow-necked bottle. After about 8h-12h, the remaining ethanol is completely removed, and finally a photon colloid with obvious structural color is obtained.

[0050] (3) Preparation of PVP-modified photonic crystal colloidal films by UV curing

[0051] Step 1: The glass slide interlayer consists of two 2cm×4cm glass slides and an 80μm spacer. Use a pipette to inject the photon colloid into the edge of the interlayer. After penetrating into the interlayer, place it in a dark place for 0.5h-1h to release the internal stress generated after the photon colloid is injected into the interlayer.

[0052] Step 2: Under an ultraviolet mercury lamp light source with a central wavelength of 365nm, the front and back sides of the photonic colloid in the glass slide interlayer are irradiated with ultraviolet light for about 20s-30s to obtain a solidified photonic crystal colloid film; then, one side of the glass slide is directly removed under normal temperature and pressure conditions to peel off the photonic crystal colloid film.

[0053] The photonic crystal colloidal film obtained above was placed under a fluorescent lamp and, with the aid of a camera, a structural color characterization test was performed at different shooting angles, and a tensile color change performance test was performed next to a steel ruler.

[0054] Example 2

[0055] The photon colloid prepared in Example 1 was used.

[0056] Preparation of PVP-modified photonic crystal colloidal films based on UV curing

[0057] Step 1: The glass slide interlayer consists of two 2cm×4cm glass slides and a 20μm spacer. Use a pipette to inject the photon colloid into the edge of the interlayer. After penetrating into the interlayer, place it in a dark place for 0.5h-1h to release the internal stress generated after the photon colloid is injected into the interlayer.

[0058] Step 2: Under an ultraviolet mercury lamp light source with a central wavelength of 365nm, the front and back sides of the photonic colloid in the glass slide interlayer are irradiated with ultraviolet light for about 20s-30s to obtain a solidified photonic crystal colloid film; then, one side of the glass slide is directly removed under normal temperature and pressure conditions to peel off the photonic crystal colloid film.

[0059] The photonic crystal colloidal film obtained above was placed under a fluorescent lamp and assisted by a camera for structural color characterization test.

[0060] Example 3

[0061] The photon colloid prepared in Example 1 was used.

[0062] Preparation of PVP-modified photonic crystal colloidal films based on UV curing

[0063] Step 1: The glass slide sandwich is composed of two 2cm×4cm glass slides. Without using a spacer, the photon colloid is injected into the edge of the sandwich using a pipette. After penetrating into the sandwich, it is placed in a light-proof condition and left to stand for 0.5h-1h to release the internal stress generated after the photon colloid is injected into the sandwich.

[0064] Step 2: Under an ultraviolet mercury lamp light source with a central wavelength of 365nm, the front and back sides of the photonic colloid in the glass slide interlayer are irradiated with ultraviolet light for about 20s-30s to obtain a solidified photonic crystal colloid film; then, one side of the glass slide is directly removed under normal temperature and pressure conditions to peel off the photonic crystal colloid film.

[0065] The photonic crystal colloidal film obtained above was placed under a fluorescent lamp and assisted by a camera for structural color characterization test.

[0066] It should be appreciated by those skilled in the art that the embodiments described herein are intended to help readers understand the principles of the present invention, and it should be understood that the scope of protection of the present invention is not limited to such specific statements and embodiments. For those skilled in the art, the present invention may have various changes and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A photonic crystal colloidal film based on PVP modification, characterized in that: The film is formed by mixing a photon crystal (1) and an elastic colloid (2) to form a photon colloid (3), and is manufactured through an ultraviolet curing process.

2. The photonic crystal colloidal film according to claim 1, wherein the photonic crystal (1) is prepared by mixing SiO2 microspheres and PVP in an ethanol solution, the particle size of the SiO2 microspheres is precisely 210 nm, and the mass ratio of SiO2 microspheres to PVP is strictly controlled at 1:

1.

3. The photonic crystal colloidal film according to claim 1, wherein the elastic colloid (2) is prepared by mixing PEGPEA and DEGEEA in an ethanol solution, and the mass ratio of PEGPEA to DEGEEA is set to 3:

1.

4. The photonic crystal colloidal film according to claim 1, characterized in that: The photonic colloid (3) is formed by mixing a photonic crystal (1) and an elastic colloid (2) in a ratio of 1:

1.

5. The photonic crystal colloidal film according to claim 1, characterized in that: During the UV curing process, the set thickness of the photonic colloid (3) is precisely controlled by the spacers in the glass slide sandwich, and the thickness range is set to be 20 μm to 80 μm.

6. A method for preparing a photonic crystal colloidal film as claimed in any one of claims 1 to 5, characterized in that: The method comprises the following steps: S1: Adoption The method was used to prepare monodispersed SiO2 microsphere particles. S2: Mix PEGPEA ethanol solution, DEGEEA ethanol solution, SiO2 ethanol suspension and PVP ethanol solution in a beaker, add photoinitiator 1173, and then perform magnetic stirring to obtain a photon colloid ethanol mixture to be evaporated; S3: The first stage of ethanol evaporation is carried out in a convection drying oven, and then the mixed solution is transferred to a brown narrow-necked bottle and the second stage of ethanol evaporation is carried out until the photon colloid is obtained; S4: Sprinkle spacers of appropriate size on a glass slide, cover it with another glass slide, infiltrate the photon colloid into the glass slide interlayer, and let it stand in the dark; S5: placing the photonic colloid to be cured under an ultraviolet light source for irradiation, ensuring that both the front and back sides are evenly irradiated, and peeling it off after a certain period of time to obtain a photonic crystal colloid film.

7. The preparation method according to claim 6, characterized in that: oIn step S1, When preparing SiO2 microspheres by the method, the amount of tetraethyl orthosilicate (TEOS) and ammonia water is 3 ml and 3.1 ml to 3.3 ml respectively, the reaction is carried out at 34°C for 5 to 6 hours, and the stirring speed is controlled at 250 rpm to 350 rpm; o In step S2, the concentrations of the SiO2 microsphere ethanol suspension and the PVP ethanol solution are both 25wt%, the concentrations of the PEGPEA ethanol solution and the DEGEEA ethanol solution are both 10wt%, the amount of the photoinitiator 1173 is 1wt% to 3wt% of the elastic colloid, and the magnetic stirring condition is 250rpm to 350rpm for 0.5 to 1 hour; o In step S3, the first stage drying condition is 60°C for 0.5 to 1 hour; the second stage drying condition is also 60°C, but the duration is extended to 8 to 12 hours; o In step S4, the ultrasonic cleaning time is 5 to 10 minutes, the plasma cleaning condition is 5 minutes, the Ar gas flow rate is 0.9ccm, the O2 gas flow rate is 200ccm, and the power is controlled at 200W to 300W; the size of the insulator matches the required film thickness, and the standing time is 0.5 to 1 hour; In step S5, the central wavelength of the ultraviolet light source is 365nm, the power is 300W to 350W, and the irradiance at the irradiation plane is 15.7mW / cm 2 Up to 18.9mW / cm 2 The UV curing time is between 20 and 30 seconds; the stripping operation is carried out directly under normal temperature and pressure conditions.

8. The preparation method according to claim 6, characterized in that: The addition of the PVP ethanol solution allows the hydrophilic groups of the PVP molecules to evenly adhere to the surface of the SiO2 microspheres to form SiO2@PVP photonic crystal particles. The hydrophobic groups of the PVP molecules help the photonic crystal particles to maintain a certain spacing during the self-assembly process, thereby forming a hexagonally closely packed photonic crystal microsphere array.

9. The preparation method according to claim 6, characterized in that: The ethanol solution of PEGPEA and DEGEEA plays a key role in the UV curing process. Their unsaturated groups interact with the free radicals formed by the decomposition of the photoinitiator to initiate addition, crosslinking or polymerization reactions. These reactions ultimately form long-chain or mesh-like polymer free radical intermediates, and the colloid is converted into a solid polymer film through a chain termination reaction. In addition, DEGEEA can also effectively reduce the modulus of the photonic crystal colloidal film, thereby improving its sensitivity, response speed and service life.

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