Magnetically controlled waterproof smart window and its femtosecond laser preparation method

Abstract

The present invention relates to a magnetically controlled waterproof smart window and a femtosecond laser preparation method thereof. The method first prepares a PTFE template, then prepares a Fe-PDMS liquid, and then obtains a smart window with magnetic response after transfer and curing demoulding, and finally evaporates a hydrophobic layer on the surface of the smart window to obtain a finished magnetically controlled waterproof smart window. The smart window includes a substrate and a plurality of microplates in a linear array attached to one side of the substrate. The visible light transmittance of the microplate is lower than that of the substrate, and each microplate can be in a bent state under the action of the introduced magnetic field, and shield the substrate between the microplates on the adjacent side. The smart window obtained by the above preparation method utilizes the optical properties and magnetic response properties of iron powder to solve the problem of medium viscosity dissipation that existed before, can be well applied to various harsh environments, and has the characteristic of rapid response. In addition, by applying a magnetic field, no contact is made with the device, and "in situ reversible" optical switching is achieved to change the light transmittance.

Description

Technical Field

[0001] The present invention relates to the technical field of optical materials, and in particular to a magnetically controlled waterproof smart window and a femtosecond laser preparation method thereof. Background Art

[0002] Smart optical materials, capable of dynamically responding to external stimuli and exhibiting tunable light transmission properties, hold great potential in applications such as smart windows (SW), wearable biosensors, filters, and electronic skin. Well-designed SW systems can save energy for heating, cooling, and lighting. Therefore, the exploration of SW is of great significance for energy storage and conservation.

[0003] In existing technologies, smart windows typically achieve optical changes by injecting ethanol into the device or by changing the physical state of paraffin wax. This results in surface viscosity dissipation issues. Furthermore, in actual applications, issues such as rainwater contamination leading to performance failure and the impact of harsh environments significantly reduce device performance and lifespan, severely hindering the practical application of smart windows. Summary of the Invention

[0004] Based on this, it is necessary to address the technical problems in the existing technology that the surface durability of smart windows is poor and optical switching is difficult. The present invention provides a magnetically controlled waterproof smart window and a femtosecond laser preparation method thereof.

[0005] The present invention discloses a femtosecond laser preparation method for a magnetically controlled waterproof smart window, comprising the following steps:

[0006] (1) Preparation of PTFE template: A PTFE plate is provided, and a plurality of strip grooves in a linear array are etched on one side of the PTFE plate using a femtosecond laser to obtain a PTFE template for use.

[0007] (2) Preparation of Fe-PDMS liquid: PDMS solution and cross-linking agent were mixed and stirred, and then Fe powder was added and stirred thoroughly until the liquid was uniformly black. The bubbles in the liquid were vacuum-evacuated to obtain Fe-PDMS liquid for use.

[0008] (3) Transfer and curing demolding: Place the PTFE template on a glass slide and fix it. Pour the Fe-PDMS liquid onto the PTFE template. Then place the PTFE template on an N52 magnet to define the magnetic field direction. After 10 seconds, remove the magnetic field and vacuum remove the bubbles in the template.

[0009] The Fe-PDMS on the outer surface of one side of the PTFE template was scraped off, and a PDMS solution was taken to cover the surface of the template to form a base layer. After heating and curing at 100°C for 1 hour, the base and the multiple Fe-PDMS microplates in the adhered linear array were demolded from the template to obtain a smart window with magnetic response.

[0010] (4) Surface treatment of the smart window: A hydrophobic layer was evaporated on the end surface of each Fe-PDMS microplate facing away from the substrate, as well as on the same side along the linear array direction, to obtain the finished product of the magnetically controlled waterproof smart window.

[0011] As a further improvement of the above solution, in step (1), the processing power of the femtosecond laser is 500 mW, the processing speed is 2 mm / s, and the number of cycles is 50 times.

[0012] As a further improvement of the above solution, the column spacing of the multiple strip grooves etched by femtosecond laser is 0.4-0.8 mm.

[0013] As a further improvement of the above scheme, in step (2), the mass ratio of PDMS solution to cross-linking agent is 5:1, and the mass ratio of Fe powder to PDMS solution is PDMS:Fe=1:1.

[0014] As a further improvement of the above solution, the particle size of the Fe powder is 20 mesh.

[0015] As a further improvement to the above scheme, the mass ratio of the PDMS solution for making the Fe-PDMS liquid to the PDMS solution for making the substrate is 1:1. The specific process of covering the template surface with the PDMS solution to form a substrate layer in step (3) is as follows:

[0016] Pour the PDMS solution completely onto the PTFE template and cover the surface of the template. Place the PDMS solution on a gel coater and keep the speed at 800 r / min for 30 s.

[0017] As a further improvement of the above scheme, in step (4), the specific process of evaporating the hydrophobic layer on the end surface of the Fe-PDMS microplate of the smart window is as follows:

[0018] The Fe-PDMS side of the smart window was placed downward on a heating plate, and a magnetic field was introduced to regulate the bending of the microplates, ensuring that each microplate could shield the substrate between the adjacent microplates.

[0019] Pour 3 mL of Glaco reagent onto the hot plate and heat to 80°C until the Glaco reagent is completely evaporated onto the end surface and the same side of each microplate, and repeat the operation 4-5 times.

[0020] The present invention also discloses a magnetically controlled waterproof smart window, which is prepared by using any of the above-mentioned femtosecond laser preparation methods for the magnetically controlled waterproof smart window.

[0021] As a further improvement of the above solution, the smart window includes a substrate and a plurality of microplates in a linear array attached to one side of the substrate.

[0022] As a further improvement of the above solution, the visible light transmittance of the microplate is lower than that of the substrate, and each microplate can be bent under the action of the introduced magnetic field and shield the substrate between the adjacent microplate.

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

[0024] This preparation method utilizes the optical and magnetic response properties of iron powder, mixing PDMS with magnetically responsive materials for the first time and applying them to the field of intelligent optics. This results in a fully solid-state optical device, resolving the previously existing problem of dielectric viscosity dissipation. It can be well applied in various harsh environments while also exhibiting rapid response characteristics. The resulting smart window changes its light transmittance without damaging its physical structure. Simply changing the direction and intensity of the magnetic field makes the optical switching of the smart window reversible. Furthermore, compared to the traditional method of injecting lubricant, which would contact the device, applying a magnetic field prevents contact with the device, achieving an "in-situ reversible" effect, allowing for multiple cycles and long-term storage.

[0025] This smart window achieves super-hydrophobicity by vapor-depositing Glaco on the end of each microplate facing away from the substrate, as well as on the same side of the linear array. This gives these surfaces relatively stable and durable surface properties, resulting in features not found in typical smart windows, such as anti-icing and self-cleaning. More importantly, the opposite side of the microplate along the array direction is free of hydrophobic reagents, which creates two modes for the smart window: hydrophobic mode and hydrophilic mode. When the microplate is upright or bent to one side, the hydrophobic layer is "exposed," giving the smart window a super-hydrophobic effect. When the microplate is bent to the other side, the hydrophobic layer "converges inward," giving the smart window a hydrophilic effect. This allows for automatic switching based on actual application needs.

[0026] In addition, the preparation method of the smart window is simple and can be produced on a large scale. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a flow chart of a femtosecond laser preparation method for a magnetically controlled waterproof smart window in a preferred embodiment of the present invention;

[0028] Figure 2 for Figure 1 Schematic diagram of the process of the preparation method;

[0029] Figure 3 This is a schematic diagram of the magnetically controlled waterproof smart window of the present invention when the micro-plate is in an upright position;

[0030] Figure 4 for Figure 3 Schematic diagram of the magnetically controlled waterproof smart window's microplate bending to one side;

[0031] Figure 5 for Figure 4 Schematic diagram of the magnetically controlled waterproof smart window's micro-plate bending toward the other side;

[0032] Figure 6 This is a local morphology image of the smart window sample prepared by the present invention at 75 times magnification under an electron microscope;

[0033] Figure 7 for Figure 6 3Dimage outline of the smart window sample;

[0034] Figure 8 is the height curve of the local microplate of the smart window sample;

[0035] Figure 9 The visible light transmittance variation curves of the samples with different row spacings in the present invention when the microplate is in an upright state;

[0036] Figure 10 The transmittance variation curves of samples with different row spacings in the present invention when the microplate is bent;

[0037] Figure 11 The contact angle variation diagram of smart window samples with different column spacings in the bent / upright state of the microplate;

[0038] Figure 12 The graph of the rolling angle change of smart window samples with different column spacing when the micro-plate is bent / upright. DETAILED DESCRIPTION

[0039] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the 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.

[0040] It should be noted that when a component is referred to as being "mounted on" another component, it may be directly on the other component or there may be a central component. When a component is considered to be "set on" another component, it may be directly set on the other component or there may be a central component. When a component is considered to be "fixed to" another component, it may be directly fixed to the other component or there may be a central component.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used herein in the specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "or / and" as used herein includes any and all combinations of one or more of the associated listed items.

[0042] See also Figure 1 and Figure 2 This embodiment provides a method for preparing a magnetically controlled waterproof smart window, comprising the following steps:

[0043] (1) Preparation of PTFE template: Provide PTFE plate, Figure 2 The I in the figure indicates that a plurality of strip grooves in a linear array are etched on one side of the PTFE plate using a femtosecond laser to obtain a PTFE template for use.

[0044] In this embodiment, PTFE (polytetrafluoroethylene) is taken as the material to be processed, and a femtosecond laser with good uniformity, high precision and low thermal effect is used for processing. The processing power is 500mw, the processing speed is 2mm / s, the number of cycles is 50 times, the processing pattern is a linear array, and the column spacing is 0.6mm. A variety of polytetrafluoroethylene templates with high precision and good uniformity can be obtained.

[0045] (2) Preparation of Fe-PDMS liquid: 1.0 g of PDMS (polydimethylsiloxane) liquid was placed in a beaker, 0.2 g of a cross-linking agent was added, and the mixture was stirred thoroughly until the liquid had good fluidity. 1.2 g of Fe powder (20 mesh particle size) was weighed and placed in a beaker, and the mixture was stirred thoroughly until the liquid had good fluidity. The mixture was placed in a vacuum chamber to remove bubbles until they disappeared. In other embodiments, the mass ratio of PDMS liquid to Fe powder may also be 1:0.3 to 1.8.

[0046] (3) Transfer and curing demoulding: Figure 2 II means that the PTFE template is fixed on a glass slide, Fe-PDMS liquid is poured on the PTFE template, and then the PTFE template is placed on an N52 magnet to define the magnetic field direction. After 10 seconds, the magnetic field is withdrawn and the template is placed in a vacuum chamber to draw vacuum until all bubbles in the template are expelled.

[0047] Take out the template and scrape off the Fe-PDMS on the outer surface of the PTFE template with a scraper. Figure 2 III means taking 1 g of PDMS solution to cover the surface of the template, placing it on a gel coater, rotating at 800 r / min for 30 s to ensure uniform thickness of each sample and forming a layer of base material on the surface of the template.

[0048] Figure 2The IV indicates that after curing on a hot plate at 100°C for one hour, the substrate and the multiple Fe-PDMS microplates with adhered linear arrays were demolded from the template to obtain a smart window with high-sensitivity magnetic response.

[0049] (4) Surface treatment of the smart window: A hydrophobic layer was evaporated on the end surface of each Fe-PDMS microplate facing away from the substrate, as well as on the same side along the linear array direction, to obtain the finished product of the magnetically controlled waterproof smart window.

[0050] Figure 2 The V represents the specific process of evaporation: the smart window with the Fe-PDMS side facing down and placed on the heating plate, the introduction of a magnetic field to control the bending of the microplate, to ensure that each microplate can cover the substrate between the adjacent microplate.

[0051] Pour 3 mL of Glaco reagent onto a hot plate and heat to 80°C until the Glaco reagent is completely evaporated onto the end faces and the same side of each microplate. Repeat this operation 4-5 times to make the end faces and the same side of the microplate superhydrophobic. The other side of each microplate opposite the hydrophobic side is free of Glaco reagent and becomes hydrophilic.

[0052] This embodiment also provides a magnetically controlled waterproof smart window, which can be prepared using the above-mentioned method for preparing a magnetically controlled waterproof smart window.

[0053] See also Figure 3 The smart window includes a substrate and a plurality of microplates in a linear array attached to one side of the substrate. Figure 3 In the figure, a represents the substrate and b represents the microplate.

[0054] The visible light transmittance of the microplate is lower than that of the substrate, and each microplate can bend under the action of the introduced magnetic field and shield the substrate between the adjacent microplate. The bending direction of the microplate is related to the direction of the magnetic field, and the bending degree of the microplate is related to the strength of the magnetic field. Figure 4 As shown in , each microplate bends to the left simultaneously under the action of the magnetic field. Figure 5 As shown in Figure 3, after the direction of the magnetic field is changed, the bending direction of each microplate also changes and bends to the right.

[0055] Since the microplate is made of black Fe-PDMS material, and the substrate is made of colorless and transparent pure PDMS material, and the microplate is able to shield the substrate when it is bent by the magnetic field. In this way, when the smart window needs to exhibit a lower light transmittance, it is only necessary to apply the introduced magnetic field to make each microplate bend along the direction of the linear array, thereby increasing the shielding of the substrate and reducing its light transmittance. When the smart window needs to exhibit a higher light transmittance, it is only necessary to cancel the introduced magnetic field to keep each microplate in an "upright" state relatively perpendicular to the substrate, thereby reducing the shielding of the substrate and improving the light transmittance. By changing the strength of the magnetic field, the deflection angle of the microplate can also be changed, thereby achieving the adjustment of the light transmittance performance.

[0056] This invention, for the first time, combines PDMS with magnetically responsive materials and applies them to the field of intelligent optics, achieving an all-solid-state optical device. This solves the previously existing problem of dielectric viscous dissipation, allowing for optimal application in a variety of harsh environments while exhibiting rapid response. The smart window changes its light transmittance without damaging its physical structure; simply changing the direction and intensity of the magnetic field makes the optical switching reversible. Furthermore, unlike traditional lubricant injection, which involves contact with the device, applying a magnetic field prevents contact with the device, achieving "in-situ reversibility" and enabling multiple cycles and long-term storage.

[0057] This smart window achieves super-hydrophobicity by vapor-depositing Glaco on the end of each microplate facing away from the substrate, as well as on the same side of the linear array. This gives these surfaces relatively stable and durable surface properties, resulting in features not found in typical smart windows, such as anti-icing and self-cleaning. More importantly, the opposite side of the microplate along the array direction is free of hydrophobic reagents, which creates two modes for the smart window: hydrophobic mode and hydrophilic mode. When the microplate is upright or bent to one side, the hydrophobic layer is "exposed," giving the smart window a super-hydrophobic effect. When the microplate is bent to the other side, the hydrophobic layer "converges inward," giving the smart window a hydrophilic effect. This allows for automatic switching based on actual application needs.

[0058] In addition, the preparation method of the smart window is simple and can be produced on a large scale.

[0059] See also Figure 6 and Figure 7 , Figure 6 This is the morphology of the smart window sample prepared by the above preparation method in this embodiment, shown under an electron microscope at 75 times magnification. Figure 7 This is the 3D image outline of the smart window sample.

[0060] See also Figure 8 , Figure 8This is the height curve of the local microplate of the smart window sample, where the horizontal axis is distance and the vertical axis is height. It can be seen from the figure that the heights of the multiple microplates of the sample prepared by the above preparation method are relatively uniform and the preparation accuracy is good.

[0061] In order to explore the relationship between the light transmittance of the smart window and the spacing between the microplates, this example also collected the visible light transmittance of the smart window with different microplate spacing in the upright and bent states at different wavelengths, and expressed it through measurement curves. Figure 9 and Figure 10 , Figure 9 The visible light transmittance change curves of samples with different column spacing when the microplate is in the upright state. Figure 10 The transmittance curves for samples with different column spacings under a bent microplate state are shown. The horizontal axis is the visible light wavelength, and the vertical axis is the transmittance.

[0062] Depend on Figure 9 and Figure 10 It is clear that for samples with the same row spacing, the smart window has a higher light transmittance (approximately 24%-62%) when the microplate is upright, but a lower light transmittance (approximately 0%-5%) when bent. Furthermore, for visible light of the same wavelength, the light transmittance of the smart window is positively correlated with the row spacing; the larger the row spacing, the higher the light transmittance.

[0063] See also Figure 11 The figure shows the contact angle variation of smart window samples with different column spacings in the bent and upright microplate states, with E-mode representing the upright state and B-mode representing the bent state. The larger the contact angle, the harder it is for liquid to adhere to the sample, and the better the self-cleaning ability of the smart window. It can be seen that the magnetically controlled waterproof smart window prepared by the present invention has a larger contact angle in the upright state, and the contact angle decreases with increasing column spacing, indicating that droplets adhere more easily to the sample and its hydrophobicity decreases.

[0064] See also Figure 12 The figure shows the change in rolling angle of smart window samples with different column spacing when the microplate is bent or upright. It can be seen that when the microplate is in a bent state, samples with various column spacings have a larger rolling angle, making it easier for droplets to adhere to the samples, indicating hydrophilicity. When the microplate is in an upright state, the rolling angle of the samples is significantly reduced, indicating strong hydrophobicity. In addition, the contact angle in the upright state increases with the increase in column spacing, making it easier for droplets to adhere to the samples, and the hydrophobicity decreases.

[0065] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0066] The above-described embodiments merely illustrate several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that a person skilled in the art would be able to make numerous modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A femtosecond laser preparation method for a magnetically controlled waterproof smart window, characterized in that: The following steps are involved: (1) Preparation of PTFE template: A PTFE plate is provided, and a plurality of linear arrays of strip grooves are etched on one side of the PTFE plate using a femtosecond laser to obtain a PTFE template for use; (2) Preparation of Fe-PDMS liquid: PDMS solution and cross-linking agent were mixed and stirred, and then Fe powder was added and stirred thoroughly until the liquid was uniformly black. The bubbles in the liquid were vacuum-evacuated to obtain Fe-PDMS liquid for use; (3) Transfer and curing demolding: Place the PTFE template on a glass slide and fix it, then pour the Fe-PDMS liquid on the PTFE template, and then place the PTFE template on an N52 magnet to define the magnetic field direction. After 10 seconds, remove the magnetic field and vacuum remove the bubbles in the template; The Fe-PDMS on one side of the PTFE template was scraped off, and a PDMS solution was applied to the template surface to form a base layer. After curing at 100°C for 1 hour, the base layer and the attached linear array of Fe-PDMS microplates were demolded from the template to obtain a magnetically responsive smart window. Among them, the Fe-PDMS microplate can shield the substrate when it is bent by the magnetic field; (4) Surface treatment of the smart window: A hydrophobic layer is evaporated on the end surface of each Fe-PDMS microplate facing away from the substrate, as well as on the same side along the linear array direction, to obtain the finished product of the magnetically controlled waterproof smart window.

2. The femtosecond laser preparation method for a magnetically controlled waterproof smart window according to claim 1, characterized in that: In step (1), the processing power of the femtosecond laser is 500 mW, the processing speed is 2 mm / s, and the number of cycles is 50 times.

3. The femtosecond laser preparation method for a magnetically controlled waterproof smart window according to claim 2, characterized in that: The row spacing of the plurality of strip grooves etched by the femtosecond laser is 0.4-0.8 mm.

4. The femtosecond laser preparation method for a magnetically controlled waterproof smart window according to claim 1, characterized in that: In step (2), the mass ratio of the PDMS solution to the cross-linking agent is 5:1, and the mass ratio of the Fe powder to the PDMS solution is PDMS:Fe=1:

1.

5. The femtosecond laser preparation method for a magnetically controlled waterproof smart window according to claim 4, characterized in that: The particle size of Fe powder is 20 mesh.

6. The femtosecond laser preparation method for a magnetically controlled waterproof smart window according to claim 1, characterized in that: The mass ratio of the PDMS solution for making the Fe-PDMS liquid to the PDMS solution for making the substrate is 1:1; wherein, in step (3), the specific process of taking the PDMS solution to cover the template surface to form a layer of substrate is as follows: Pour the PDMS solution completely onto the PTFE template and cover the surface of the template. Place the PDMS solution on a gel coater and keep the speed at 800 r / min for 30 s.

7. The femtosecond laser preparation method for a magnetically controlled waterproof smart window according to claim 1, characterized in that: In step (4), the specific process of evaporating the hydrophobic layer on the end surface of the Fe-PDMS microplate of the smart window is as follows: The smart window, with the Fe-PDMS side facing downward, was placed on a heating plate. A magnetic field was introduced to control the bending of the microplates, ensuring that each microplate could shield the substrate between the adjacent microplates. Pour 3 mL of Glaco reagent onto the hot plate and heat to 80°C until the Glaco reagent is completely evaporated onto the end surface and the same side of each microplate, and repeat the operation 4-5 times.

8. A magnetically controlled waterproof smart window, characterized in that: It is prepared by the femtosecond laser preparation method of the magnetically controlled waterproof smart window as described in any one of claims 1 to 7.

9. The magnetically controlled waterproof smart window according to claim 8, characterized in that: The smart window includes a substrate and a plurality of microplates attached to one side of the substrate in a linear array.

10. The magnetically controlled waterproof smart window according to claim 9, characterized in that: The visible light transmittance of the microplate is lower than that of the substrate, and each microplate can be bent under the action of the introduced magnetic field and shield the substrate between the microplate on the adjacent side.

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