CN112300309B

CN112300309B - Preparation method of stretchable flexible electrochromic film

Info

Publication number: CN112300309B
Application number: CN202011188939.7A
Authority: CN
Inventors: 付少海; 张丽平; 李加双; 田安丽
Original assignee: Jiangnan University
Current assignee: Jiangnan University
Priority date: 2020-10-30
Filing date: 2020-10-30
Publication date: 2021-07-27
Anticipated expiration: 2040-10-30
Also published as: CN112300309A

Abstract

The invention discloses a preparation method of a stretchable flexible electrochromic film, and belongs to the technical field of fine chemical engineering and material science. Mixing electrolyte, color-changing dye, organic monomer and solvent, adding initiator, stirring and forming film to obtain the stretchable flexible electrochromic film; the organic monomer comprises one or more of acrylamide, N-hydroxymethyl acrylamide, hydroxyethyl acrylate, hydroxypropyl acrylate, methyl acrylate ethyl acrylate, butyl acrylate, isooctyl acrylate, N-methylene bisacrylamide and polyethylene glycol diacrylate. The color-changing film prepared by the method has the characteristics of high electric response speed, high color contrast and the like, and also has good tensile recovery, the tensile strain can reach 500%, the tensile recovery rate is 98.0%, and the diversified requirements of people on wearable electronic products can be met.

Description

Preparation method of stretchable flexible electrochromic film

Technical Field

The invention relates to a preparation method of a stretchable flexible electrochromic film, belonging to the technical field of fine chemical engineering and material science.

Background

At present, an intelligent wearable electronic product is a new high-tech product with huge market potential, and has wide application prospects in the fields of anti-counterfeiting packaging, medical use, sensors, textiles and the like. Materials related to wearable electronic products are required to have better mechanical properties, namely, the materials can still keep the original properties without performance degradation after being subjected to external force; at the same time, the material is required to respond quickly to electrical signals and to be able to display microscopic response data optimally in macroscopically visible color changes. Therefore, the electrochromic flexible film material capable of fast response is a component of wearable electronic products.

Electrochromic film materials typically comprise two major portions: 1) a color-changing system mainly comprises an electrochromic body, an electrolyte, a cosolvent and the like; 2) the film material determines the properties of the electrochromic film material, such as finishing mechanics, machinery and the like.

The fluorane color-changing dye is an organic reversible color-changing material with electric response performance, the color-changing principle is that the dye is stimulated by an electric field to generate redox reaction, the structure of the dye is changed (shown as the opening and closing of a lactone ring), and therefore the reversible change of the color is realized. CN201810659646.9 discloses an alkali-responsive electrochromic film and a preparation method thereof, wherein fluorescein or phenolphthalein and the like are used as raw materials, a gel solution containing dye is coated on ITO conductive glass in a coating mode to obtain a sol film, and the sol film is dried to obtain the alkali-responsive electrochromic film. The film forming mode can ensure that the layers are tightly attached, and the film has excellent response sensitivity and color development uniformity. However, the steady-state time for discoloration of the film is short and is not described in terms of flexibility of the material.

At present, most of electrochromic films adopt methods such as spin coating, magnetron sputtering and the like to coat a color-changing material on a glass or plastic substrate, and then the color-changing material is dried, thermally treated and the like to form a hard film on the substrate. The color-changing film has single use and is difficult to meet the current requirements on wearable electronic products. In addition, the flexible electrochromic film in the current research is difficult to rapidly recover deformation after being deformed by stress, and has no tensile recovery. The problem also seriously affects the stability of the electrochromic product and the wearability of the wearable textile, and restricts the development of the electrochromic material in the field of wearable electronic products.

Disclosure of Invention

In order to solve the problems, the invention prepares the flexible electrochromic film with high response speed, high color contrast and good tensile recovery by searching suitable electrolyte, color-changing dye, monomer, polymer and solvent and mixing the electrolyte, the color-changing dye, the monomer, the polymer and the solvent according to a certain proportion to carry out solution polymerization. The film prepared by the invention shows good reversible color-changing performance under the stimulation of positive and negative voltages; under the condition of power failure and no negative voltage application, the film can keep the color not fading and shows good steady-state performance. In addition, the film prepared by the invention has excellent stretch recovery and meets the requirements of wearable electronic products.

The first purpose of the invention is to provide a preparation method of a stretchable flexible electrochromic film, wherein reaction raw materials comprise electrolyte, color-changing dye, monomer, solvent and initiator, and the method comprises the steps of mixing the electrolyte, the color-changing dye, the monomer and the solvent, adding the initiator, stirring and forming a film to obtain the stretchable flexible electrochromic film; the monomer comprises one or more of acrylamide, N-hydroxymethyl acrylamide, hydroxyethyl acrylate, hydroxypropyl acrylate, methyl acrylate ethyl acrylate, butyl acrylate, isooctyl acrylate, N-methylene bisacrylamide and polyethylene glycol diacrylate.

In one embodiment of the invention, a polymer can be further added in the method, wherein the addition amount of the polymer accounts for 0-20% of the total mass percent of the system, and the addition amount of the polymer is g/g; the polymer is selected from polymethyl methacrylate, polybutyl methacrylate, poly-2-hydroxyethyl methacrylate or polymethyl acrylate.

In one embodiment of the present invention, the amount of each raw material added is 1 to 10% by mass of the electrolyte based on the total mass of the system; the mass percentage of the color-changing dye is 0.01-0.5%; the mass percent of the solvent is 5-40%; the mass percentage of the organic monomer is 40-90%.

In one embodiment of the invention, the addition amount of the initiator accounts for 0.1-5% of the mass percent of the organic monomer, and the addition amount is g/g.

In one embodiment of the invention, 1-10% by mass of electrolyte, 0-20% by mass of polymer and 0.01-0.5% by mass of color-changing dye are added into an organic solvent to be ultrasonically stirred for 5-20 minutes to form a uniform solution, wherein the organic solvent accounts for 5-40% by mass of the system; adding monomers accounting for 40-90% of the mass percent of the system into the uniform solution, and stirring for 1-10 minutes to fully mix uniformly; adding an initiator with the monomer content of 0.1-5%, and continuously stirring for 1-10 minutes; transferring the obtained solution into a glass culture dish, carrying out defoaming treatment in a vacuum oven for 1-30 min, then heating to 30-80 ℃, and keeping the temperature for reaction for 0.5-12 hours; and taking out the film after the reaction is completed and cooling the film to room temperature to obtain the flexible electrochromic film.

In one embodiment of the present invention, the color-changing dye selected for use is selected from one or more of fluorane-based color-changing dyes, including one or more of 2 '-chloro-6' - (diethylamino) fluorane, 2 '-chloro-6' - (diethylamino) -3 '-methylfluorane, 6' - (diethylamino) -1 ', 3' -dimethylfluorane, triarylmethanes, and fluoresceins.

In one embodiment of the invention, the electrolyte selected is tetrabutylammonium perchlorate (TBAP), tetrabutylammonium hexafluorophosphate (TBAPF6), tetraethylammonium perchlorate, tetramethylammonium hexafluorophosphate, mercuric chloride, barium sulfate or lead acetate.

In one embodiment of the invention, the organic solvent selected is propylene carbonate.

In one embodiment of the invention, the initiator is selected from the group consisting of potassium persulfate, a mixed system of ammonium persulfate and tetramethylethylenediamine, azobisisobutyronitrile, azobisisoheptonitrile, and benzoyl peroxide.

The second purpose of the invention is to provide an electrochromic film prepared by the method.

The third purpose of the invention is to provide the application of the electrochromic film in the aspects of electronic skin and flexible displays.

The fourth purpose of the invention is to provide an intelligent textile, and the preparation method of the intelligent textile is to integrate the electrochromic film with clothes and an induction device through a packaging method to obtain the intelligent textile capable of inducting and displaying human body functions.

The invention has the beneficial effects that:

the color-changing film prepared by the method has the characteristics of high electric response speed, high color contrast and the like, and also has good tensile recovery, the tensile strain can reach 450%, the tensile recovery rate is 98.0%, and the diversified requirements of people on wearable electronic products can be met. In addition, the driving voltage of the color-changing film prepared by the method is lower than 3V (far lower than the human body safety voltage of 36V), and the film is powered on and changed in color and then powered off, so that the steady-state time of 1-6 days can be reached, and therefore, the material has wide application prospects in the fields of wearable electronic products, energy conservation, environmental protection and the like.

Detailed Description

The following description of the preferred embodiments of the present invention is provided for the purpose of better illustrating the invention and is not intended to limit the invention thereto.

1. And (3) measuring the tensile property:

and (3) adopting a universal tensile machine to represent the mechanical property of the film and verify the tensile recovery of the color-changing film.

2. And (3) measuring the color change performance:

and attaching the color-changing film to a flexible substrate with electrodes, then covering another layer of flexible substrate with electrodes, and obtaining the display device after assembling. Taking two pieces of ITO glass as reference, testing the transmissivity curves of the colorless film and the developed film by Morpho3.2 software and an FX2000 spectrometer, and determining the final transmissivity of the film by the transmissivity value of the film (dye) at the position of the maximum absorption wavelength of 501 nm; and driving the device by adopting a direct current steady-state power supply, and verifying the color change performance of the color change film according to the color change phenomenon.

Example 1:

5mg of 2 '-chloro-6' - (diethylamino) fluorane, 0.5g of tetrabutylammonium perchlorate (TBAP) and 3.5g of hydroxypropyl acrylate were added to 1g of propylene carbonate solution, and sonication was carried out for 10 minutes to obtain a clear mixed solution. Adding 80 mul of azodiisoheptanonitrile initiator, stirring for 5 minutes, pouring into a glass culture dish, vacuumizing for 10 minutes at normal temperature, heating to 60 ℃, vacuum polymerizing for 2 hours, taking out and cooling to room temperature to obtain a colorless transparent film. The transmittance of the color-changing film is 92%, the tensile strain can reach 300%, and the tensile recovery rate is 95%. The color can be developed under the drive of 3V voltage, and the stable state can be maintained for 5 days after the voltage is removed.

Example 2:

0.2g of polymethyl methacrylate was added to 1g of propylene carbonate, and the mixture was left to stand at 90 ℃ for 24 hours to dissolve, thereby obtaining a gel solution. Taking out and cooling to normal temperature, adding 5mg of 2 '-chloro-6' - (diethylamino) fluorane, 0.5g of tetrabutylammonium perchlorate (TBAP), 3mg of N, N-methylene bisacrylamide and 3.3g of hydroxypropyl acrylate, and carrying out ultrasonic treatment for 10 minutes to obtain a clear mixed solution. Adding 80 mul of azodiisobutyronitrile initiator, stirring for 5 minutes, pouring into a glass culture dish, vacuumizing for 10 minutes at normal temperature, heating to 70 ℃, carrying out vacuum polymerization for 2 hours, taking out, and cooling to room temperature to obtain a colorless transparent film. The transmittance of the color-changing film is 94%, the tensile strain can reach 300%, and the tensile recovery rate is 98%. The color can be developed under the drive of 3V voltage, and the stable state can be kept for 6 days after the voltage is removed.

Example 3:

0.2g of polymethyl methacrylate was added to 1g of propylene carbonate, and the mixture was left to stand at 90 ℃ for 24 hours to dissolve, thereby obtaining a gel solution. Taking out and cooling to normal temperature, adding 5mg of 2 '-chloro-6' - (diethylamino) fluorane, 0.5g of tetrabutylammonium perchlorate (TBAP) and 3.3g of hydroxypropyl acrylate, and carrying out ultrasonic treatment for 10 minutes to obtain a clear mixed solution. Adding 100 mu l of aqueous solution containing 15mg of ammonium persulfate, uniformly stirring, stirring 10 mu l of tetramethylethylenediamine, stirring for 5 minutes, pouring into a glass culture dish, vacuumizing at normal temperature for 10 minutes, then heating to 50 ℃, carrying out vacuum polymerization for 2 hours, taking out, and cooling to room temperature to obtain a substantially colorless transparent film. The transmittance of the color-changing film is 92%, the tensile strain can reach 450%, and the tensile recovery rate is 98%. The color can be developed under the drive of 4V voltage, and the stable state of 1 day can be maintained after the voltage is removed.

Example 4:

5mg of 2 '-chloro-6' - (diethylamino) fluorane, 0.5g of tetrabutylammonium perchlorate (TBAP), 3mg of N, N-methylenebisacrylamide, and 3.5g of hydroxypropyl acrylate were added to 1g of the propylene carbonate solution, and sonication was performed for 10 minutes to obtain a clear mixed solution. Adding 80 mul of azodiisoheptanonitrile initiator, stirring for 5 minutes, pouring into a glass culture dish, vacuumizing for 10 minutes at normal temperature, heating to 60 ℃, vacuum polymerizing for 2 hours, taking out and cooling to room temperature to obtain a colorless transparent film. The transmissivity of the color-changing film is 93%, the tensile strain can reach 300%, and the tensile recovery rate is 99%. The color can be developed under the drive of 3V voltage, and the stable state can be kept for 6 days after the voltage is removed.

Example 5: selection of organic monomers

An electrochromic film was manufactured according to the method of example 1 except that the kind of monomer was adjusted to replace hydroxypropyl acrylate with methyl methacrylate, methyl acrylate, isobutyl acrylate, n-butyl acrylate and isooctyl acrylate, and other conditions were the same as those of example 1, and the properties of the obtained electrochromic film were shown in table 1.

TABLE 1 Properties of electrochromic films

Note: "-" indicates that the membrane material is not shaped or discolored and has no mechanical or discoloring property characterization.

Example 6: selection of the amount of organic monomer added

An electrochromic film was produced by referring to the method of example 1 except that the addition amount of hydroxypropyl acrylate was adjusted to 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85% (mass fraction based on the total mass of the system), and the properties of the electrochromic film produced under the same conditions as in example 1 were shown in table 2.

TABLE 2 Properties of electrochromic films

Example 7: selection of addition amount of crosslinking monomer N, N-methylene-bisacryloyl

An electrochromic film was produced by referring to the method of example 1 except that the addition amounts of the crosslinking monomer N, N-methylenebisacryloyl were adjusted to 0.06%, 0.1%, 0.2%, 0.3% (mass% based on the total mass of the system), and the properties of the electrochromic film produced under the same conditions as in example 1 were shown in table 3.

TABLE 3 mechanical Properties of electrochromic films

Example 8: intelligent textile

An intelligent textile is prepared by the steps of obtaining a precursor solution of the electrochromic film through a high-temperature curing method on a transparent conductive flexible polyester substrate, and then packaging the precursor solution with another flexible polyester substrate; the patterns are designed at different positions before curing, the intelligent textile can provide targeted response color change for clothing, different colors and patterns are displayed through power supply control, the multi-color of the textile is realized to adapt to various occasions, and the pursuit of people for clothing individuality is met.

Although the present invention has been described with reference to the preferred embodiments, it should be understood that various changes and modifications can be made therein by those skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A preparation method of a stretchable flexible electrochromic film is characterized in that reaction raw materials comprise electrolyte, color-changing dye, monomer, solvent and initiator, the method comprises the steps of mixing the electrolyte, the color-changing dye, the monomer and the solvent, adding the initiator, stirring and forming a film to obtain the stretchable flexible electrochromic film; the monomer is hydroxyethyl acrylate, hydroxypropyl acrylate or methyl methacrylate and a crosslinking monomer N, N-methylene-bisacrylamide; the dosage of the N, N-methylene bisacrylamide is 0 to 0.2 percent; the addition amount of each raw material is 1-10% of the total mass of the system by mass of the electrolyte; the mass percentage of the color-changing dye is 0.01-0.5%; the mass percent of the solvent is 5-40%; the mass percentage of the monomer is 40-90%; the selected color-changing dye is selected from one or more of fluorane color-changing dyes.

2. The method according to claim 1, characterized in that a polymer can be further added in the method, wherein the addition amount of the polymer accounts for 0-20% of the total mass percent of the system; the polymer is selected from polymethyl methacrylate, polybutyl methacrylate, poly-2-hydroxyethyl methacrylate or polymethyl acrylate.

3. The method of claim 1, wherein the color-changing dye comprises one or more of 2 '-chloro-6' - (diethylamino) fluoran, 2 '-chloro-6' - (diethylamino) -3 '-methylfluoran, 6' - (diethylamino) -1 ', 3' -dimethylfluoran, triarylmethanes, and fluoresceins.

4. The method of claim 2, wherein the color-changing dye comprises one or more of 2 '-chloro-6' - (diethylamino) fluoran, 2 '-chloro-6' - (diethylamino) -3 '-methylfluoran, 6' - (diethylamino) -1 ', 3' -dimethylfluoran, triarylmethanes, and fluoresceins.

5. The method of any one of claims 1 to 4, wherein the electrolyte is selected from tetrabutylammonium perchlorate, tetrabutylammonium hexafluorophosphate, tetraethylammonium perchlorate, tetramethylammonium hexafluorophosphate, mercuric chloride, barium sulfate or lead acetate.

6. A process according to any one of claims 1 to 4, characterized in that the solvent used is propylene carbonate.

7. The method according to claim 5, characterized in that the solvent used is propylene carbonate.

8. The method of any one of claims 1-4, 7, wherein the initiator is selected from the group consisting of potassium persulfate, a mixed system of ammonium persulfate and tetramethylethylenediamine, azobisisobutyronitrile, azobisisoheptonitrile, and benzoyl peroxide.

9. The method of claim 5, wherein the initiator is selected from the group consisting of potassium persulfate, a mixed system of ammonium persulfate and tetramethylethylenediamine, azobisisobutyronitrile, azobisisoheptonitrile, and benzoyl peroxide.

10. The method of claim 6, wherein the initiator is selected from the group consisting of potassium persulfate, a mixed system of ammonium persulfate and tetramethylethylenediamine, azobisisobutyronitrile, azobisisoheptonitrile, and benzoyl peroxide.

11. An electrochromic film prepared by the process according to any one of claims 1 to 10.

12. Use of the electrochromic film according to claim 11 for electronic skin, flexible displays.

13. An intelligent textile, characterized in that the preparation method of the intelligent textile is to combine the electrochromic film of claim 11 with clothes and induction devices by a packaging method to obtain the intelligent textile capable of induction display to human body.