Photochromic film as well as preparation method and application thereof

Abstract

The invention provides a preparation method of a photochromic film, which can be applied to the technical field of functional film materials, and the method comprises the following steps: preparing a mixed solution of titanium dioxide (TiO2) and poly (3, 4-ethylenedioxythiophene)-poly (styrene sulfonate) (PEDOT: PSS); preparing a substrate; placing the mixed solution on a substrate to obtain a sample to be treated; the sample to be treated is subjected to annealing treatment, and the titanium dioxide coated poly (3, 4-ethylenedioxythiophene)-poly (styrene sulfonate) (PEDOT: PSS coated TiO2) composite photochromic film is obtained. The photochromic film can realize a remarkable photochromic effect under the irradiation of ultraviolet light; the color changing and fading process of the photochromic film is influenced by environment humidity and atmosphere, and the photochromic film has adjustability and good stability; the photochromic film has wide application potential in the fields of intelligent windows, rewritable paper, solar ultraviolet detection and the like. The invention also provides a photochromic film and application thereof.

Description

Technical Field

[0001] The invention relates to the technical field of functional thin film materials, and in particular to a photochromic thin film and a preparation method and application thereof. Background Art

[0002] As a hot area in cutting-edge scientific research, electrochromic and photochromic materials have shown great potential in imaging technology, information storage and other aspects. In traditional research, these two color-changing phenomena are often classified as two independent disciplines, each developing along a different path. However, this segmented research method is limited in thinking and the solution is not satisfactory when faced with common problems such as slow response speed and dependence on short-wave excitation light. The integrated development of electrochromic and photochromic has brought a new perspective and ideas to break this dilemma.

[0003] So far, there has been no report showing that organic matter can have both electrochromic and photochromic functions. Therefore, it is particularly important to deeply explore the correlation and universality of the internal physical laws of electrochromism and photochromism. This requires us to finely control the transfer and transport mechanism of carriers and ions inside electrochromic / photochromic polymer materials to explore whether it can achieve a perfect fusion of the two color-changing functions.

[0004] Furthermore, we need to study the redox characteristics of electrochromism and the intrinsic mapping relationship of various mechanisms of action in photochromism in depth. By revealing these deep scientific laws, we are expected to achieve flexible switching of photo / electrochromic behavior and inject new vitality into the development of this cutting-edge field. Summary of the invention

[0005] 1. Technical issues to be resolved

[0006] In order to solve at least one of the above-mentioned technical problems existing in the prior art, the embodiments of the present invention provide a photochromic film and a preparation method and application thereof, aiming to realize the use of classic electrochromism for photochromism and solve the problems of insufficient performance stability, response speed and color change range of photochromic materials.

[0007] (II) Technical solution

[0008] In view of the above technical problems, embodiments of the present invention provide a photochromic film and a preparation method and application thereof.

[0009] According to a first aspect of the present invention, a method for preparing a photochromic film is provided, comprising: preparing a mixed solution of titanium dioxide and poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate); preparing a substrate; placing the mixed solution on the substrate to obtain a sample to be treated; and annealing the sample to be treated to obtain a titanium dioxide@poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) composite photochromic film.

[0010] In some exemplary embodiments, preparing a mixed solution of titanium dioxide and poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) includes: dissolving titanium dioxide nanoparticles in water and performing ultrasonic treatment to obtain a titanium dioxide dispersion; mixing the titanium dioxide dispersion with an aqueous solution of poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) to obtain a mixed solution of titanium dioxide and poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate).

[0011] In some exemplary embodiments, the substrate includes a quartz substrate, and preparing the substrate includes: preliminarily cleaning the quartz substrate, and then ultrasonically cleaning the quartz substrate with deionized water, acetone and isopropanol respectively; placing the quartz substrate after ultrasonic cleaning into an ethanol solution; when using, taking the quartz substrate out of the ethanol solution, blowing dry the ethanol on the surface of the substrate with dry nitrogen, and performing ultraviolet-ozone treatment.

[0012] In some exemplary embodiments, placing the mixed solution on the substrate includes spin coating the mixed solution on the substrate according to first process parameters, wherein the first process parameters include: a rotation speed of 1500 rpm±100 rpm; and a time of 60 s±10 s.

[0013] In some exemplary embodiments, the process parameters for annealing the sample to be processed include: an annealing temperature of 120° C.±10° C.; and an annealing time of 20 min±5 min.

[0014] In some exemplary embodiments, the substrate includes filter paper, and annealing the sample to be processed includes: annealing the sample to be processed to evaporate water in the sample to be processed.

[0015] In some exemplary embodiments, the mass fraction of titanium dioxide in the mixed solution is 18.18 wt.%-57.14 wt.%.

[0016] In some exemplary embodiments, the average particle size of titanium dioxide nanoparticles is 20 nm; the concentration of titanium dioxide in the titanium dioxide dispersion is 26 mg / ml±3 mg / ml; the mass fraction of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) in the aqueous solution of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) is 1.3±0.2 wt.%.

[0017] According to a second aspect of the present invention, a photochromic film is provided. The photochromic film is prepared by the above method.

[0018] According to a third aspect of the present invention, there is provided an application of a photochromic film prepared by the above method, which can be applied to the fields of smart windows, rewritable paper and solar ultraviolet detection.

[0019] (III) Beneficial effects

[0020] It can be seen from the above technical solutions that a photochromic film and a preparation method and application thereof provided by the embodiments of the present invention have at least the following beneficial effects:

[0021] (1) By optimizing the loading amount, crystal form and ambient atmosphere of titanium dioxide (TiO2), the photochromic film can achieve a significant photochromic effect under ultraviolet light.

[0022] (2) The discoloration and fading process of the photochromic film is affected by the ambient humidity and atmosphere, and is adjustable and has good stability.

[0023] (3) This photochromic film has broad application potential in smart windows, rewritable paper, solar ultraviolet light detection and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The above contents and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

[0025] Figure 1 A schematic diagram of a process for preparing a photochromic film according to an embodiment of the present invention is shown;

[0026] Figure 2 Schematically showing the change in transmittance of composite films with different TiO2 loadings before and after ultraviolet irradiation according to an embodiment of the present invention;

[0027] Figure 3 A schematic diagram showing the change in absorbance of composite films with different TiO2 loadings before and after ultraviolet irradiation according to an embodiment of the present invention; and

[0028] Figure 4The schematic diagram of the ACS encoding application process implemented by TiO2@PEDOT:PSS carbon paper according to an embodiment of the present invention is schematically shown. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings. Obviously, the described embodiments are 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 creative work are within the scope of protection of the present invention.

[0030] Figure 1 The flowchart of a method for preparing a photochromic film according to an embodiment of the present invention is schematically shown.

[0031] like Figure 1 As shown, a method for preparing a photochromic film according to an embodiment of the present invention includes steps S110 to S140.

[0032] In step S110 , a mixed solution of titanium dioxide and poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (TiO 2 @PEDOT:PSS mixed solution) is prepared.

[0033] In an embodiment of the present invention, step S110 may include: dissolving titanium dioxide nanoparticles in water and performing ultrasonic treatment to obtain a titanium dioxide dispersion; mixing the titanium dioxide dispersion with an aqueous solution of poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS) to obtain a mixed solution of titanium dioxide and poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate). Preferably, the average particle size of the titanium dioxide nanoparticles is 20 nm; the concentration of titanium dioxide in the titanium dioxide dispersion is 26 mg / ml±3 mg / ml; the mass fraction of poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) in the aqueous solution of poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) is 1.3±0.2wt.%; and the mass fraction of titanium dioxide in the mixed solution is: 18.18wt.%-57.14wt.%.

[0034] In step S120 , a substrate is prepared.

[0035] In the embodiment of the present invention, the substrate includes a quartz substrate or filter paper.

[0036] When the substrate is a quartz substrate, preparing the substrate includes: preliminarily cleaning the quartz substrate, and then ultrasonically cleaning the quartz substrate with deionized water, acetone and isopropanol respectively; placing the quartz substrate after ultrasonic cleaning in an ethanol solution; when using, taking the quartz substrate out of the ethanol solution, blowing dry the ethanol on the surface of the substrate with dry nitrogen, and performing ultraviolet-ozone treatment.

[0037] In step S130, the mixed solution is placed on a substrate to obtain a sample to be processed.

[0038] In the embodiment of the present invention, when the substrate is a quartz substrate, the power supply and air pump of the coating machine are turned on, the substrate is placed in the coating machine and the suction is turned on. The speed is set to 1500 rpm±100 rpm, the time is 60s±10s, the TiO2@PEDOT:PSS mixed solution is spin-coated on the quartz substrate, and the sample is spin-coated on the substrate according to the first process parameters.

[0039] In the embodiment of the present invention, when the substrate is filter paper, the TiO2@PEDOT:PSS mixed solution is dropped on the filter paper.

[0040] In step S140, the sample to be treated is annealed to obtain a titanium dioxide@poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) composite photochromic film.

[0041] In the embodiment of the present invention, when the substrate is a quartz substrate, the process parameters for annealing the sample to be processed include: an annealing temperature of 120° C.±10° C.; and an annealing time of 20 min±5 min.

[0042] In the embodiment of the present invention, when the substrate is filter paper, the sample to be processed is annealed to evaporate the water in the sample to be processed.

[0043] According to the photochromic film prepared by the embodiment of the present invention, the TiO2 nanoparticles can absorb ultraviolet light and generate electron-hole pairs, in which the electrons absorb energy from the valence band and are excited to transition to the conduction band. In view of the fact that the conduction band potential of the TiO2 nanoparticles is higher than the Fermi level of PEDOT:PSS, the electrons in the conduction band of TiO2 can be transferred to PEDOT:PSS, resulting in dedoping of PEDOT:PSS. This process will reduce the bipolaron state of PEDOT:PSS and turn it into a polaron state. At the same time, the holes left in the valence band will be captured by the H2O molecules on the surface, which accelerates and promotes the redox reaction, thereby enhancing the photochromic effect. This photochromic mechanism enables the film to exhibit a significant color change effect under ultraviolet light irradiation.

[0044] The discoloration and fading process of the film is affected by the ambient humidity and atmosphere, and has adjustability and good stability. It can be applied to smart windows, rewritable paper, and solar ultraviolet detection.

[0045] Example 1: Preparation of four TiO2@PEDOT:PSS composite photochromic films with different TiO2 loading amounts.

[0046] In operation step S1, four TiO2@PEDOT:PSS mixed solutions with different TiO2 contents were prepared.

[0047] Specifically, 0.26 g of commercial TiO2 nanoparticles with an average particle size of 20 nm were dissolved in a 10 ml glass bottle and ultrasonicated for 20 min to obtain a 26 mg / ml TiO2 dispersion; TiO2 nanoparticles with different loadings were uniformly dispersed in a 1.3 wt.% PEDOT:PSS aqueous solution to obtain a TiO2@PEDOT:PSS mixed solution. The mass fractions of TiO2 in the four groups of solutions with different TiO2 mass contents were 18.18 wt.%, 33.33 wt.%, 46.15 wt.% and 57.14 wt.%, respectively.

[0048] In operation step S2, the surface of the substrate is treated with ultraviolet-ozone.

[0049] Specifically, the substrate used in the embodiment of the present invention is a quartz (TiO2) substrate, the size of the quartz substrate is 15 mm×15 mm, and the thickness of the quartz is 1 mm. The quartz substrate is first cleaned with diluted detergent, and then ultrasonically cleaned with deionized water, acetone and isopropanol for 20 minutes respectively, and then placed in ethanol for standby use. After the quartz substrate is taken out of the ethanol, the ethanol on the surface of the substrate is blown dry with dry nitrogen, and ultraviolet-ozone treatment is performed at room temperature for 15 minutes.

[0050] In operation step S3, the solution is dripped onto the surface of the substrate, and the sample is prepared by spin coating using preset parameters.

[0051] Specifically, the process includes turning on the power supply and air pump of the coating machine, placing the substrate in operation step S2 in the coating machine, and starting the suction. The rotation speed is set to 1500 rpm, the time is 1 min, and the spin coating sample preparation is started to obtain 4 groups of samples.

[0052] In operation step S4, the substrate is placed on a hot stage for thermal annealing to obtain a TiO2@PEDOT:PSS composite photochromic film on the substrate.

[0053] Specifically, the sample spin-coated in step S3 is taken out and placed on a hot stage. The parameters are set to 120°C for 20 min, and thermal annealing is started to finally obtain TiO2@PEDOT:PSS composite photochromic films with different TiO2 contents.

[0054] Figure 2 A schematic diagram showing the change in transmittance of composite films with different TiO2 loadings before and after ultraviolet irradiation according to an embodiment of the present invention is shown; and Figure 3 The schematic diagram shows the change in absorbance of composite films with different TiO2 loadings before and after ultraviolet irradiation according to an embodiment of the present invention.

[0055] Depend on Figure 2 and Figure 3 It can be seen that the transmittance of the composite film with different TiO2 loadings before and after ultraviolet irradiation according to the embodiments of the present disclosure can be observed in the visible light range and the near-infrared range, and the transmittance decreases.

[0056] Figure 4 The schematic diagram of the ACS encoding application process implemented by TiO2@PEDOT:PSS carbon paper according to an embodiment of the present invention is schematically shown.

[0057] like Figure 4 As shown in the figure, two different PEDOT:PSS inks were diluted and dropped onto a circular filter paper. One was pure PEDOT:PSS ink, and the other was 33.33wt.% TiO2@PEDOT:PSS ink. Before UV irradiation, it was difficult to distinguish the colors of the two inks, and no useful information could be read. After UV irradiation, they could be clearly distinguished, and the three letters SUT edited using the ACS code could be effectively read.

[0058] Figure 4The main principle of the experiment shown is that PEDOT:PSS is a conductive polymer with good electrical conductivity and stability; TiO2 is a photocatalyst that can generate photogenerated electrons and holes under UV light irradiation. When TiO2 is composited with PEDOT:PSS, the photocatalytic properties of TiO2 will affect the optical or electrical properties of PEDOT:PSS. Pure PEDOT:PSS ink and PEDOT:PSS composite ink containing 33.33wt.% TiO2 were prepared and diluted. The two inks were dropped on a circular filter paper to form a testable sample. Before UV light irradiation, the colors of the two inks were difficult to distinguish because their initial optical properties were very similar. At this time, no useful information could be read from the filter paper. When the filter paper was irradiated with UV light, the TiO2 particles in the TiO2@PEDOT:PSS composite ink absorbed UV light and generated photogenerated electrons and holes. These photogenerated electrons and holes interacted with PEDOT:PSS, causing the optical properties of the composite ink to change and its color to become darker. Since pure PEDOT:PSS ink does not contain TiO2, its optical properties remain basically unchanged under UV light. The color change of TiO2@PEDOT:PSS composite ink under UV light can be used to encode information on filter paper. By controlling the droplet addition of ink and the irradiation of UV light, a specific binary pattern can be formed on the filter paper, thereby encoding the required information.

[0059] This experiment demonstrates the potential application of the photoresponse characteristics of PEDOT:PSS and TiO2 composite ink in information encoding and decoding. By controlling the composition of the ink and the irradiation conditions of ultraviolet light, information hiding and visibility can be achieved, which has broad application prospects in the fields of information security and anti-counterfeiting labels.

[0060] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a photochromic film, characterized in that: The method comprises: preparing a mixed solution of titanium dioxide and poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate); preparing a substrate; placing the mixed solution on the substrate to obtain a sample to be processed; The sample to be processed is annealed to obtain a titanium dioxide@poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) composite photochromic film.

2. The method according to claim 1, characterized in that: The method for preparing a mixed solution of titanium dioxide and poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) comprises: dissolving titanium dioxide nanoparticles in water and subjecting the water to ultrasonic treatment to obtain a titanium dioxide dispersion; The titanium dioxide dispersion is mixed with an aqueous solution of poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) to obtain a mixed solution of titanium dioxide and poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate).

3. The method according to claim 1 or 2, characterized in that: The substrate comprises a quartz substrate, and the prepared substrate comprises: Performing preliminary cleaning on the quartz substrate, and then performing ultrasonic cleaning on the quartz substrate with deionized water, acetone and isopropanol respectively; The ultrasonically cleaned quartz substrate is placed in an ethanol solution; When in use, the quartz substrate is taken out from the ethanol solution, the ethanol on the surface of the substrate is blown dry with dry nitrogen, and then subjected to ultraviolet-ozone treatment.

4. The method according to claim 3, characterized in that Placing the mixed solution on the substrate includes spin coating the mixed solution on the substrate according to a first process parameter, Wherein, the first process parameters include: The speed is 1500rpm±100rpm; The time is 60s±10s.

5. The method according to claim 3, characterized in that: The process parameters for annealing the sample to be processed include: The annealing temperature is 120°C ± 10°C; and The annealing time is 20min±5min.

6. The method according to claim 1 or 2, characterized in that: The substrate includes filter paper, and the annealing treatment of the sample to be processed includes: annealing the sample to be processed to evaporate water in the sample to be processed.

7. The method according to claim 1, characterized in that The mass fraction of titanium dioxide in the mixed solution is: 18.18wt.%-57.14wt.%.

8. The method according to claim 2, characterized in that: The average particle size of the titanium dioxide nanoparticles is 20 nm; The concentration of titanium dioxide in the titanium dioxide dispersion is 26 mg / ml±3 mg / ml; The mass fraction of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) in the aqueous solution of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) is 1.3±0.2 wt.%.

9. A photochromic film, characterized in that: The photochromic film is prepared by the method according to any one of claims 1 to 8.

10. An application of a photochromic film prepared by the method according to any one of claims 1 to 8, characterized in that: Applications include smart windows, rewritable paper, and solar UV detection.

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