CN116100838B

CN116100838B - Magnetically controlled waterproof smart window and its femtosecond laser preparation method

Info

Publication number: CN116100838B
Application number: CN202310106242.8A
Authority: CN
Inventors: 陈超; 姚浩; 郭思佳; 张晨初; 李家文; 吴东
Original assignee: Hefei University of Technology
Current assignee: Hefei University of Technology
Priority date: 2023-02-13
Filing date: 2023-02-13
Publication date: 2025-09-12
Anticipated expiration: 2043-02-13
Also published as: CN116100838A

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

Magnetic control waterproof intelligent window and femtosecond laser preparation method thereof

Technical Field

The invention relates to the technical field of optical materials, in particular to a magnetic control waterproof intelligent window and a femtosecond laser preparation method thereof.

Background

Smart optical materials are capable of dynamic response to external stimuli and have adjustable light transmission characteristics due to their great potential in the fields of Smart Windows (SW), wearable biosensors, filters, and electronic skin. Through the SW system with reasonable design, heating, refrigerating and illumination energy sources can be saved. Thus, the exploration of SW has important implications for energy storage and conservation.

In the prior art, the intelligent window generally realizes the optical change of the intelligent window by injecting ethanol into the device or by means of the physical state change of paraffin, etc., so that the surface of the intelligent window has the problem of medium viscous dissipation. Meanwhile, in the practical application process, the problems of performance failure, severe environmental influence and the like caused by rainwater pollution exist, the performance and the service life of devices are greatly reduced, and the practical application of the intelligent window is seriously hindered.

Disclosure of Invention

Based on the above, the invention provides a magnetic control waterproof intelligent window and a femtosecond laser preparation method thereof, which are necessary to solve the technical problems that the intelligent window surface in the prior art has poor durability and is not easy to carry out optical switching.

The invention discloses a femtosecond laser preparation method of a magnetic control waterproof intelligent window, which comprises the following steps:

(1) And preparing a PTFE template, namely providing a PTFE plate, and processing and etching a plurality of linear array grooves on one side of the PTFE plate by using femtosecond laser to obtain the PTFE template for standby.

(2) And (3) preparing the Fe-PDMS liquid, namely mixing and stirring the PDMS solution and the cross-linking agent, then adding Fe powder, fully stirring until the liquid is uniformly black, and vacuumizing to remove bubbles in the liquid to obtain the Fe-PDMS liquid for later use.

(3) Transferring, solidifying and demoulding, namely placing a PTFE template on a glass sheet for fixing, pouring Fe-PDMS liquid on the PTFE template, placing the PTFE template on an N52 magnet for defining the magnetic field direction, withdrawing the magnetic field after 10s, and vacuumizing to remove bubbles in the template.

Scraping the Fe-PDMS on the outer surface of one side of the PTFE template, covering the template surface with PDMS solution to form a layer of substrate, heating and curing at 100 ℃ for 1h, and demolding a plurality of linear array Fe-PDMS micro plates adhered to the substrate from the template to obtain the intelligent window with magnetic response.

(4) And (3) carrying out surface treatment on the intelligent window, namely evaporating a hydrophobic layer on the end surface of each Fe-PDMS micro plate, which is away from the substrate, and the same side along the linear array direction to obtain a finished product of the magnetic control waterproof intelligent window.

As a further improvement of the above scheme, in the step (1), the processing power of the femtosecond laser is 500mw, the processing speed is 2mm/s, and the number of cycles is 50.

As a further improvement of the scheme, the array spacing of the femtosecond laser etching a plurality of strip grooves is 0.4-0.8mm.

As a further improvement of the above scheme, in the step (2), the mass ratio of the PDMS solution to the crosslinking agent is 5:1, and the mass ratio of the Fe powder to the PDMS solution is PDMS: fe=1:1.

As a further improvement of the above-mentioned scheme, the particle size of the Fe powder was 20 mesh.

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

pouring PDMS solution into PTFE template, covering on the surface of the template, and placing in a spin coater, wherein the rotation speed is 800r/min, and the time is 30s.

As a further improvement of the scheme, in the step (4), the specific process of evaporating the hydrophobic layer on the end face of the Fe-PDMS microplate of the intelligent window is as follows:

The intelligent window is arranged on the side with the Fe-PDMS downwards and above the heating plate, and magnetic field is introduced to regulate the bending of the microplates, so that each microplate can shield the substrate between the microplates on the adjacent side.

3ML Glaco of the reagent is poured into a heating plate, the heating temperature is 80 ℃ until Glaco of the reagent is evaporated to the end face and the same side face of each microplate, and the operation is repeated for 4-5 times.

The invention also discloses a magnetic control waterproof intelligent window, which is prepared by adopting the femtosecond laser preparation method of any one of the magnetic control waterproof intelligent windows.

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

As a further improvement of the scheme, the visible light transmittance of the micro-plates is smaller than that of the substrate, and each micro-plate can be in a bending state under the action of an introduced magnetic field and shade the substrate between the micro-plates on the adjacent side.

Compared with the prior art, the technical scheme disclosed by the invention has the following beneficial effects:

The preparation method utilizes the optical characteristic and the magnetic response characteristic of the iron powder, mixes PDMS with the magnetic response material for the first time and applies the mixture to the field of intelligent optics, realizes an all-solid-state optical device, solves the problem of medium viscosity dissipation existing before, can be well applied to various severe environments, and has the characteristic of quick response. The intelligent window that the preparation obtained need not to cause the destruction to the physical structure of intelligent window at the in-process of changing light transmissivity, only need change the direction and the intensity of magnetic field for the optics of intelligent window switches reversibly, and compares in traditional injection lubricating oil can contact the mode of device, can not produce the contact with the device through the mode of applying the magnetic field, realizes "normal position reversible" effect, thereby can circulate and place for a long time many times.

The intelligent window is provided with Glaco which is evaporated on the end part of each micro plate, which is away from the substrate, and the same side surface of the linear array, so that the surfaces have superhydrophobicity and have stable and durable surface properties, and therefore, the intelligent window has the characteristics which are not possessed by common intelligent windows such as anti-icing, self-cleaning and the like. More importantly, the surface of the opposite side of the micro plate along the array direction is not provided with a hydrophobic reagent, so that two modes, namely a hydrophobic mode and a hydrophilic mode, are brought to the intelligent window, when the micro plate is vertical or bent to one side, the hydrophobic layer is exposed to the outside, so that the intelligent window has a superhydrophobic effect, and when the micro plate is bent to the other side, the hydrophobic layer is converged inwards, so that the intelligent window has a hydrophilic effect, and therefore, the intelligent window can be switched automatically according to the actual application requirements.

In addition, the preparation method of the intelligent window is simple in process and can realize large-scale production.

Drawings

FIG. 1 is a flow chart of a method for preparing a femtosecond laser of a magnetic control waterproof intelligent window in a preferred embodiment of the invention;

FIG. 2 is a schematic process diagram of the preparation method of FIG. 1;

FIG. 3 is a schematic view of the magnetically controlled waterproof smart window of the present invention in an upright position on a microplate;

FIG. 4 is a schematic view of the magnetically controlled waterproof smart window of FIG. 3 with the microplate bent to one side;

FIG. 5 is a schematic view of the magnetically controlled waterproof smart window of FIG. 4 with the microplate bent to the other side;

FIG. 6 is a graph of the local morphology of a sample of the smart window prepared according to the present invention, as shown at 75 x magnification in an electron microscope;

FIG. 7 is a 3Dimage outline of the smart window sample of FIG. 6;

FIG. 8 is a plot of the height of a local microplate of a smart window sample;

FIG. 9 is a graph showing the change in visible light transmittance of samples of different column pitches in the present invention in the standing state of the microplate;

FIG. 10 is a graph showing the transmittance change curve of samples of different column pitches in the bending state of a microplate according to the present invention;

FIG. 11 is a graph of the change in contact angle of smart window samples at different column spacings in the bent/upright state of the microplate;

Fig. 12 is a graph of roll angle change in a curved/upright state of a microplate for smart window samples of different column spacing.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

It is noted that when an element is referred to as being "mounted to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "secured to" another element, it can be directly secured to the other element or intervening elements may also be present.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "or/and" as used herein includes any and all combinations of one or more of the associated listed items.

Referring to fig. 1 and 2, the present embodiment provides a method for preparing a magnetic control waterproof intelligent window, which includes the following steps:

(1) Preparation of PTFE templates A PTFE sheet is provided, and I in FIG. 2 represents the use of a femtosecond laser to machine and etch a plurality of linear array grooves on one side of the PTFE sheet to obtain a PTFE template for standby.

In the embodiment, PTFE (polytetrafluoroethylene) is taken as a material to be processed, 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 cycle number is 50, the processing pattern is a linear array, and the column spacing is 0.6mm, so that a plurality of polytetrafluoroethylene templates with high precision and good uniformity can be obtained.

(2) Preparation of Fe-PDMS liquid by adding 1.0gPDMS (polydimethylsiloxane) liquid into beaker, adding 0.2g of cross-linking agent, stirring thoroughly until the liquid fluidity is good, weighing 1.2g of Fe powder (particle size of 20 mesh) into beaker, stirring thoroughly until the liquid fluidity is good, and placing into vacuum chamber to remove air bubbles until the air bubbles disappear. In other embodiments, the mass ratio of PDMS liquid to Fe powder may also be 1:0.3-1.8.

(3) Transfer printing and curing demoulding, wherein II in figure 2 shows that a PTFE template is placed on a glass sheet for fixation, then Fe-PDMS liquid is poured on the PTFE template, then the PTFE template is placed on an N52 magnet for defining the magnetic field direction, the magnetic field is withdrawn after 10 seconds, and the template is placed in a vacuum chamber for vacuum pumping until all bubbles in the template are discharged.

Taking out the template, scraping the Fe-PDMS on the outer surface of the PTFE template by using a scraper, and covering 1g of PDMS solution on the surface of the template in a spin coater at 800r/min for 30s to ensure uniform thickness of each sample and form a layer of substrate material on the surface of the template in a III mode of FIG. 2.

FIG. 2 IV shows that after one hour of curing on a 100℃hotplate, a linear array of multiple Fe-PDMS microplates with substrate and adhesion were released from the template, resulting in a smart window with high sensitivity magnetic response.

The specific process of evaporation is shown in V in FIG. 2, wherein one side of the intelligent window with Fe-PDMS is downward and is positioned above a heating plate, and a magnetic field is introduced to regulate the bending of the microplates, so that each microplate can shield a substrate between the microplates at the adjacent side.

3ML Glaco of reagent is poured into a heating plate, the heating temperature is 80 ℃ until Glaco of the reagent is evaporated to the end face and the same side face of each microplate, and the operation is repeated for 4-5 times, so that the end face and the same side face of each microplate are super-hydrophobic, and the other side of each microplate opposite to the hydrophobic side is free of Glaco reagent and is hydrophilic.

The embodiment also provides a magnetic control waterproof intelligent window, which can be prepared by adopting the preparation method of the magnetic control waterproof intelligent window.

Referring to fig. 3, the smart window includes a substrate, and a plurality of microplates attached to one side of the substrate in a linear array. In fig. 3, a denotes a substrate, and b denotes a microplate.

Wherein, the visible light transmittance of the micro-plate is smaller than that of the substrate, and each micro-plate can be in a bending state under the action of an introduced magnetic field and shade the substrate between the micro-plate and the adjacent micro-plate. Wherein the bending direction of the microplate is related to the magnetic field direction, and the bending degree of the microplate is related to the strength of the magnetic field. As shown in fig. 4, each microplate is simultaneously bent to the left by the magnetic field. As shown in fig. 5, after the magnetic field direction is changed, the bending direction of each microplate is changed and bent rightward.

Since the microplate is made of black Fe-PDMS material, the substrate is made of colorless transparent pure PDMS material, and the microplate can shield the substrate when being bent by the action of a magnetic field. Thus, when the intelligent window is required to show lower light transmittance, only an induced magnetic field is required to be applied, so that each micro plate is bent along the direction of the linear array, the shielding generated on the substrate is increased, and the light transmittance is reduced. When the intelligent window is required to present higher light transmittance, only the introduced magnetic field is required to be withdrawn, so that each micro plate is kept in a vertical state relatively perpendicular to the substrate, the shielding on the substrate is reduced, and the light transmittance is improved. The deflection angle of the micro plate can be changed by changing the intensity of the magnetic field, so that the light transmittance performance can be adjusted.

According to the invention, PDMS and a magnetic response material are mixed for the first time and applied to the field of intelligent optics, so that an all-solid-state optical device is realized, the problem of medium viscous dissipation existing before the device is solved, the device can be well applied to various severe environments, and the device has the characteristic of quick response. The intelligent window is in the in-process of changing the light transmissivity, need not to cause the destruction to the physical structure of intelligent window, only need change the direction and the intensity of magnetic field for the optics of intelligent window switches reversibly, and compares in traditional injection lubricating oil can contact the mode of device, can not produce the contact with the device through the mode of applying the magnetic field, realizes "normal position reversible" effect, thereby can circulate and place for a long time many times.

Referring to fig. 6 and 7, fig. 6 shows the morphology of the smart window sample prepared by the preparation method in this embodiment at a magnification of 75 times by using an electron microscope. Fig. 7 is a 3Dimage outline of a smart window sample.

Referring to fig. 8, fig. 8 is a graph showing the height of a local microplate of an intelligent window sample, the horizontal axis is the distance, and the vertical axis is the height, and it can be seen from this graph that the sample prepared by the above preparation method has a relatively uniform height of a plurality of microplates and good preparation accuracy.

In order to explore the relation between the light transmittance of the intelligent window and the distance between the micro plates, in this embodiment, the visible light transmittance of the intelligent window with different distance between the micro plates is also collected, and the visible light transmittance of the intelligent window with different wavelengths is represented by a measurement curve in an upright and bending state. Referring to fig. 9 and 10, fig. 9 shows the visible light transmittance change curves of samples with different column pitches in the microplate standing state. FIG. 10 is a graph showing the transmittance change curves of samples of different column pitches in the bent state of the microplate. The abscissa is the wavelength of visible light and the ordinate is the transmittance.

As is evident from fig. 9 and 10, for samples of the same column spacing, the smart window has a higher light transmission (about 24% -62%) when standing upright and a lower light transmission (about 0% -5%) when bent. In addition, for visible light with the same wavelength, the light transmittance of the intelligent window is positively correlated with the size of the column pitch, and the larger the column pitch is, the higher the light transmittance is.

Referring to fig. 11, which shows the change in contact angle for different column spacing smart window samples in the bent/erect state of the microplate, wherein E-mode represents the erect state and B-mode represents the bent state. The larger the contact angle, the more difficult the liquid will adhere to the sample and the better the self-cleaning ability of the smart window. It can be seen that the magnetic control waterproof intelligent window prepared by the invention has a larger contact angle in an upright state, the contact angle is reduced along with the increase of the column spacing, the easier the liquid drop is adhered to a sample, and the hydrophobicity is reduced.

Referring to fig. 12, there are shown smart window samples of different column spacing, roll angle variation in the bent/upright state of the microplate. It can be seen that when the microplate is in a bent state, samples with various column pitches have larger rolling angles, and droplets are more likely to adhere to the samples and have hydrophilicity. And when the microplate is in an upright state, the rolling angle of the sample is obviously reduced, and the microplate has stronger hydrophobicity. And in the upright state, the contact angle increases with the increase of the column pitch, and the more easily the droplet adheres to the sample, the lower the hydrophobicity.

The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.

The above examples merely represent a few embodiments of the present invention, which are described in more detail and are not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of the invention should be assessed as that of the appended claims.

Claims

1. The femtosecond laser preparation method of the magnetic control waterproof intelligent window is characterized by comprising the following steps of:

(1) Providing a PTFE plate, and processing and etching a plurality of linear array strip-shaped grooves on one side of the PTFE plate by using femtosecond laser to obtain the PTFE template for standby;

(2) Mixing and stirring the PDMS solution and the cross-linking agent, then adding Fe powder, fully stirring until the liquid is uniformly black, and vacuumizing to remove bubbles in the liquid to obtain the Fe-PDMS liquid for later use;

(3) Transferring, solidifying and demoulding, namely placing a PTFE template on a glass sheet for fixing, pouring Fe-PDMS liquid on the PTFE template, placing the PTFE template on an N52 magnet for defining the magnetic field direction, withdrawing the magnetic field after 10 seconds, and vacuumizing to remove bubbles in the template;

scraping the Fe-PDMS on the outer surface of one side of the PTFE template, covering the template surface with PDMS solution to form a layer of substrate, heating and curing for 1h at 100 ℃, and demolding a plurality of linear array Fe-PDMS micro plates adhered to the substrate from the template to obtain an intelligent window with magnetic response;

Wherein, the Fe-PDMS micro-plate can shield the substrate when being bent under the action of a magnetic field;

2. The method for preparing the femtosecond laser of the magnetic control waterproof intelligent window according to claim 1, wherein in the step (1), the processing power of the femtosecond laser is 500mw, the processing speed is 2mm/s, and the cycle number is 50.

3. The method for preparing the femtosecond laser of the magnetic control waterproof intelligent window according to claim 2, wherein the column spacing of the plurality of strip-shaped grooves etched by the femtosecond laser is 0.4-0.8mm.

4. The femtosecond laser preparation method of the magnetic control waterproof intelligent window according to claim 1, wherein in the 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 method for preparing the femtosecond laser of the magnetic control waterproof intelligent window according to claim 4, wherein the particle size of the Fe powder is 20 meshes.

6. The femtosecond laser preparation method of the magnetic control waterproof intelligent window of claim 1 is characterized in that the mass ratio of a PDMS solution for preparing Fe-PDMS liquid to a PDMS solution for preparing a substrate is 1:1, wherein in the step (3), the specific process of covering the template surface with the PDMS solution to form a layer of substrate is as follows:

7. The femtosecond laser preparation method of the magnetic control waterproof intelligent window according to claim 1, wherein in the step (4), the specific process of evaporating the hydrophobic layer on the end surface of the Fe-PDMS micro-plate of the intelligent window is as follows:

The intelligent window is arranged on the side with the Fe-PDMS downwards and above the heating plate, and magnetic field is introduced to regulate and control the bending of the microplates, so that each microplate can shield the substrate between the microplates on the adjacent side;

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 according to any one of claims 1 to 7.

9. The magnetically controlled water resistant smart window of claim 8, wherein the smart window comprises a substrate and a plurality of microplates attached to one side of the substrate in a linear array.

10. The magnetically controlled water resistant smart window of claim 9, wherein the microplates have a visible light transmittance less than that of the substrate, and each microplate is capable of assuming a curved state under the influence of the induced magnetic field and shielding the substrate from adjacent microplates.