Visual monitoring interface pressure distribution piezochromic micro-nano fiber film large-scale preparation method

Abstract

The present application relates to the technical field of material science, and particularly relates to a visual monitoring interface pressure distribution piezochromic micro-nano fiber film large-scale preparation method, the present application utilizes the irreversible plastic deformation principle of plastic polymer under pressure, and a multilayer ultrathin piezochromic film of micro-nano fiber layer-by-layer construction is prepared by electrospinning method with polyacrylonitrile and polymethyl methacrylate as raw materials; irreversible plastic deformation occurs after pressure, which induces the disappearance of interlayer and intralayer pores, changes the light scattering path, causes irreversible transparency change, and provides long-term stable pressure information recording capability; and the piezochromic film can be combined with a color film or a bromine cesium lead fluorescent film as a substrate to obtain a new structure piezochromic film which can be separated and combined as needed, the pressure monitoring resolution is obviously improved, and the piezochromic film has the advantages of real-time, convenience, stability and applicability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of material science, and in particular to a large-scale preparation method of a pressure-induced transparent micro-nano fiber film for visual monitoring of interface pressure distribution. BACKGROUND

[0002] The electrical signal pressure monitoring has excellent response speed and sensitivity, but the complex preparation process (micro-nano processing), high cost (electronic devices and array), harsh and limited test conditions and the dependence on multi-device cooperation seriously hinder its practical application.

[0003] The pressure-induced color change material (PCM) is a new type of intelligent material that changes color obviously under the action of pressure, including pressure-induced fluorescent color change material, pressure-induced phosphorescent color change material and pressure-induced transparent material. In recent years, researchers use the color change rate to correlate the interface pressure size and distribution by using the different color characteristics of PCM under different pressures, that is, the two-dimensional real-time graph of micro-nano interface pressure size and distribution is obtained by color change rate. Most of the PCMs are prepared by taking high polymers as the main body, without the need for multi-device cooperation, which reduces the manufacturing cost. In addition, PCM does not need external driving or reading circuit, and is simple and convenient to use, with low test requirements. Generally, PCM does not contain electronic elements and electrodes, and high-pressure in-situ monitoring will not affect the stability of the pressure sensor, with excellent robustness. The unique advantages of PCM make it have important application value in the fields of pressure sensing, information storage, interface pressure monitoring, product anti-counterfeiting and optoelectronic devices, especially in high-end manufacturing industry, which seriously depends on the pressure feedback provided by PCM for assembly, security check and acceptance.

[0004] At present, PCM is mainly divided into four categories: organic fluorescent small molecules represented by spiropyrans, one-dimensional photonic crystals such as cellulose nanocrystals, conformational conversion covalent organic metal frameworks and color-changing microcapsule composite films. Microcapsule composite film is the only commercialized PCM film at present, such as the pressure-sensitive film developed by Japan's Foxconn Company, but the color transition after the capsule rupture has instantaneous and random diffusion, which is difficult to continuously and accurately record the pressure information, and the spatial resolution of the pressure-sensitive film can only reach 100 microns, which is far from meeting the requirements of accurately monitoring the micro-nano interface pressure information.

[0005] Therefore, according to the related technology in the above, it is urgent to develop a large-scale preparation method of a pressure-induced transparent micro-nano fiber film for visual monitoring of interface pressure distribution. SUMMARY

[0006] Therefore, the present application aims to provide a large-scale preparation method of a pressure-induced transparent micro-nano fiber film for visual monitoring of interface pressure distribution, so as to solve the problem of low resolution of PCM film in the pressure monitoring process in the prior art.

[0007] Based on the above purpose, the application provides a visual monitoring interfacial pressure distribution piezochromic micro-nano fiber film large-scale preparation method.

[0008] A visual monitoring interfacial pressure distribution piezochromic micro-nano fiber film large-scale preparation method, comprising the following steps:

[0009] Step S1. Add a plastic polymer to an organic solvent, heat and stir to make it uniformly mixed to obtain a polymer solution A;

[0010] Step S2. Test and record the viscosity and surface tension of the polymer solution A, and combine the electrospinning parameters to control the electrospinning fiber diameter, thereby adjusting the micro-nano fiber film pressure detection range;

[0011] Step S3. Add the polymer solution A to the electrospinning injector, push the injector piston until no bubbles escape from the solution, turn on the electrospinning device, set the spinning parameters, and obtain a layer-by-layer constructed micro-nano fiber film. The prepared film is white and opaque.

[0012] Step S4. Prepare a color film or fluorescent film substrate, and use the lamination method to prepare a separate piezochromic material. The preparation method of the cesium lead bromide fluorescent film substrate is as follows: dissolve cesium bromide and lead bromide in polymethyl methacrylate and N,N-dimethylformamide (25%) respectively, control the concentration of cesium bromide and lead bromide to be 1%-5%, mix them thoroughly to obtain a mixed solution; take a clean glass sheet and place it on the adsorption table of a high-speed spin coater, preheat the mixed solution to 70°C, and then drop a small amount of it on the glass sheet and spin at high speed to obtain a spin coating film; transfer the spin coating film to a hot stage at 80°C and anneal for 2 minutes. The volatilization of N,N-dimethylformamide induces the formation of cesium lead bromide nanocrystals, thereby obtaining a uniform green fluorescent cesium lead bromide film.

[0013] Step S4. Use the mask lithography method established in the laboratory to prepare a mold with microstructures. The microstructure is a strip pattern. Control the lithography mask and etching conditions to obtain a mold with different strip spacings for obtaining pressure monitoring resolution.

[0014] Step S5. Use software such as Solidworks to model and combine 3D printing to build a ring-shaped uniform light source (ultraviolet light and sunlight) for obtaining a two-dimensional pressure distribution map.

[0015] The polymer polymer in step S1 is any one of plastic polymers such as polyacrylonitrile, polymethyl methacrylate, or polyvinyl butyral. According to the modulus of the used polymer, the pressure detection range can be adjusted.

[0016] Preferably, the polymer is a plastic hydrophobic polymer with a molecular weight of 104 -10 5 g / ml, and a micro-nano fiber film with good fiber morphology can be obtained by using a suitable molecular weight.

[0017] Preferably, the organic solvent in step S1 is obtained by mixing N,N-dimethylformamide and acetone at a mass ratio of 6.5-7.5:2.5-3.5.

[0018] The mass ratio of the high molecular compound to the organic solvent is 1-3:7-20.

[0019] The temperature during the heating and stirring is 50-70 DEG C, and the stirring rate is 260-320 rpm.

[0020] Preferably, the diameter of the electrospinning injector in step S3 is 8-10 cm, and the injection speed is 0.8-1.2 mL / h.

[0021] In the spinning parameters, the positive voltage of the electrostatic field is 6-15 kv, the negative voltage is 2-3 kv, the rotating speed of the collection roller is 80-200 rpm, the distance between the spinning nozzle and the collection roller is 10-20 cm, and the spinning time is 1-5 h.

[0022] Preferably, the thickness of the micro-nano fiber film in step S3 is 20-60 mu m.

[0023] The present application has the following beneficial effects:

[0024] The present application provides a visual monitoring interface pressure distribution piezochromic micro-nano fiber film large-scale preparation method, which utilizes the irreversible plastic deformation of plastic polymer under pressure, and uses polyacrylonitrile or polymethyl methacrylate plastic polymer as raw material to prepare a multi-layer ultrathin piezochromic film with layer-by-layer construction of micro-nano fibers, and can be combined with color film or cesium bromide lead fluorescent film to obtain a new structure piezochromic film which can be separated and combined as needed, and the pressure monitoring resolution is obviously improved.

[0025] The polyacrylonitrile and polymethyl methacrylate plastic polymer has intrinsic plasticity and hydrophobicity, and has good stability in the film; and the multi-layer ultrathin piezochromic film with layer-by-layer construction of micro-nano fibers has a thickness of 20-60 mu m, the layer-by-layer assembly of the internal polymer fibers and the pore structure between the fibers make it have multiple scattering of light, and present an opaque state, but under the induction of pressure, the internal polymer fiber layers gradually disappear, the disappearance of the interlayer and intralayer pores makes the light uniformly pass through, reduces the multiple scattering of light, and makes it present different transparency under different pressure, and this irreversibility makes it can accurately record the pressure information.

[0026] And the separated pressure-induced color change film prepared by the pressure-induced transparent micro-nano fiber film and the cesium bromide lead film substrate can be color changed in air for a long time and stably, and has super high resolution. The real-time, convenient, stable and applicable advantages combined with the expandability, large-scale potential and high resolution make the application have more extensive application prospect compared with the prior art. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the application or prior art, the drawings needed to be used in the following examples or prior art description will be briefly introduced. Obviously, the drawings in the following description can also be used to obtain other drawings without creative labor for those skilled in the art.

[0028] Figure 1 The micro-nano fiber film prepared in example 1 and example 2 of the application;

[0029] Figure 2 The scanning electron microscope images of the internal pore structure of the micro-nano fiber film prepared in example 1 and example 2 of the application before and after applying pressure;

[0030] Figure 3 The transparency measured by ultraviolet transmission spectrum of the micro-nano fiber film prepared in example 1 and example 2 of the application after applying different pressures;

[0031] Figure 4 The transparency and fluorescence transmittance of the micro-nano fiber film prepared in example 1 of the application combined with the cesium bromide lead film under different applied pressures;

[0032] Figure 5 The resolution of the micro-nano fiber film prepared in example 2 of the application combined with the cesium bromide lead film. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the application more clear and obvious, the application will be further described in detail below combined with specific examples.

[0034] The sources and properties of some raw materials used in the application are as follows:

[0035] The polymethyl methacrylate is purchased from Dongguan Fulin Plastic Raw Material Co., Ltd., the polyacrylonitrile is purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., the N,N-dimethylformamide is purchased from Nantong Zhonghe New Material Chemical Co., Ltd., and the acetone is purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0036] Example 1: A large-scale preparation method of a pressure-induced transparent micro-nano fiber film for visual monitoring of interfacial pressure distribution, comprising the following steps:

[0037] S1. Add 1 g of polyacrylonitrile with a molecular weight of 60000 g / mol to 7 g of organic solvent, wherein the organic solvent is obtained by mixing 6.5 g of N,N-dimethylformamide and 3.5 g of acetone, heated to 50℃, mixed uniformly at a stirring rate of 320 rpm, to obtain a high polymer solution A;

[0038] S2. Add the high polymer solution A to a diameter of 10 cm electrospinning injector at an injection rate of 0.8 mL / h, push the injector piston until no bubbles escape from the solution, open the electrospinning device, set the positive voltage of the electrostatic field to 7kv, the negative voltage to 2kv, the collection roller speed to 80 rpm, the distance between the spinning nozzle and the collection roller to 18 cm, and the spinning time to 1h, to obtain a piezochromatic micro-nanofiber film;

[0039] Step S3. Prepare a color film or fluorescent film substrate, and use the piezochromatic material prepared in step S2 to prepare a separate piezochromatic material by lamination, wherein the preparation method of the cesium lead bromide fluorescent film substrate is as follows: dissolve cesium bromide and lead bromide in polymethyl methacrylate and N,N-dimethylformamide (25%) respectively, control the concentration of cesium bromide and lead bromide to be 1%-5%, and mix them thoroughly; take a clean glass sheet and place it on the adsorption table of a high-speed spin coater, preheat the mixed solution to 70℃, and then drop a small amount of the solution onto the glass sheet and spin at high speed to obtain a spin coating film; transfer the spin coating film to a hot stage at 80℃ and anneal for 2 min, and the volatilization of N,N-dimethylformamide induces the formation of cesium lead bromide nanocrystals, thereby obtaining a uniform green fluorescent cesium lead bromide film;

[0040] Step S4. Use the mask photolithography method established in the laboratory to prepare a mold with a surface microstructure, wherein the microstructure is a strip pattern, which is used to obtain a pressure monitoring resolution;

[0041] Step S5. Use software such as Solidworks to model and combine 3D printing to build a ring-shaped uniform light source (ultraviolet light and sunlight) for obtaining a two-dimensional pressure distribution map.

[0042] Example 2: A method for visualizing and monitoring the pressure distribution of a piezochromatic micro-nanofiber film, comprising the following steps:

[0043] S1. Add 1 g of polymethyl methacrylate with a molecular weight of 15000 g / mol to 7 g of organic solvent, wherein the organic solvent is obtained by mixing 7 g of N,N-dimethylformamide and 3 g of acetone, heated to 55℃, mixed uniformly at a stirring rate of 300 rpm, to obtain a high polymer solution A;

[0044] S2. The high molecular solution A is added to the electrospinning injector with a diameter of 10 cm at an injection rate of 0.9 mL / h, the injector piston is pushed until no bubbles escape from the solution, the electrospinning device is opened, the positive voltage of the electrostatic field is set to 7.5 kv, the negative voltage is set to 2.5 kv, the collection drum rotation speed is set to 90 rpm, the distance between the spinning nozzle and the collection drum is set to 18 cm, the spinning time is 4.5 h, and a piezochromatic micro-nanofiber film is obtained;

[0045] S3. A color film or fluorescent film substrate is prepared, and the micro-nanofiber film obtained in step S2 is prepared into a separate piezochromic material by lamination, wherein the preparation method of the cesium lead bromide fluorescent film substrate is as follows: cesium bromide and lead bromide are respectively dissolved in polymethyl methacrylate and N,N-dimethylformamide (25%), the concentration of cesium bromide and lead bromide is controlled to be 1%-5%, and they are fully mixed; a clean glass sheet is taken and placed on the adsorption table of a high-speed spin coater, the mixed solution is preheated to 70°C, a small amount of the solution is dropped on the glass sheet, and high-speed rotation is performed to obtain a spin coating film; the spin coating film is transferred to a hot stage at 80°C, and annealed for 2 min, the volatilization of N,N-dimethylformamide induces the formation of cesium lead bromide nanocrystals, thereby obtaining a uniform green fluorescent cesium lead bromide film;

[0046] S4. A mold with a surface microstructure is prepared by a mask lithography method established in the laboratory, wherein the microstructure is a strip pattern, which is used to obtain a pressure monitoring resolution;

[0047] S5. An annular uniform light source (ultraviolet light and sunlight) is built by modeling using software such as Solidworks combined with 3D printing, which is used to obtain a pressure distribution two-dimensional diagram.

[0048] Example 3: A visual monitoring interface pressure distribution piezochromatic micro-nanofiber film large-scale preparation method, comprising the following steps:

[0049] S1. 2 g of polyvinyl butyral with a molecular weight of 90000 g / mol is added to 15 g of organic solvent, wherein the organic solvent is obtained by mixing 7 g of ethanol and 3 g of water, heated to 60°C, and mixed uniformly at a stirring rate of 280 rpm to obtain a high molecular solution A;

[0050] S2. The high molecular solution A is added to the electrospinning injector with a diameter of 10 cm at an injection rate of 1 mL / h, the injector piston is pushed until no bubbles escape from the solution, the electrospinning device is opened, the positive voltage of the electrostatic field is set to 7.5 kv, the negative voltage is set to 2.5 kv, the collection drum rotation speed is set to 100 rpm, the distance between the spinning nozzle and the collection drum is set to 19 cm, the spinning time is 4 h, and a piezochromatic micro-nanofiber film is obtained;

[0051] S3. Prepare a color film or fluorescent film substrate, and prepare a separated pressure-induced chromic material by using the lamination method with the micro-nano fiber film obtained in step S2 and the substrate, wherein the preparation method of the cesium lead bromide fluorescent film substrate is as follows: dissolve cesium bromide and lead bromide in polymethyl methacrylate and N,N-dimethylformamide (25%) respectively, and control the concentration of cesium bromide and lead bromide to be 1%-5%, and mix them thoroughly; take a cleaned glass sheet and place it on the adsorption table of a high-speed spin coater, preheat the mixed solution to 70°C, take a small amount and drop it on the glass sheet, and then spin at high speed to obtain a spin coating film; transfer the spin coating film to a hot stage at 80°C, and anneal for 2 min, and the volatilization of N,N-dimethylformamide induces the formation of cesium lead bromide nanocrystals, thereby obtaining a uniform green fluorescent cesium lead bromide film;

[0052] S4. Use the mask photolithography method established in the laboratory to prepare a mold with a surface microstructure, wherein the microstructure is a strip pattern, which is used to obtain a pressure monitoring resolution;

[0053] S5. Use software such as Solidworks to model and combine 3D printing to build a ring-shaped uniform light source (ultraviolet light and sunlight) for obtaining a two-dimensional pressure distribution map.

[0054] Example 4: A visual monitoring interface pressure distribution pressure-induced transparent micro-nano fiber film large-scale preparation method, comprising the following steps:

[0055] S1. Add 2g of polystyrene with a molecular weight of 80000g / mol to 15g of organic solvent, wherein the organic solvent is 13g of N,N-dimethylformamide, heated to 65°C, mixed uniformly at a stirring speed of 260rpm, to obtain a high molecular weight solution A;

[0056] S2. Add the mixture B to a diameter of 10cm electrospinning injector at an injection rate of 1.1mL / h, push the injector piston until no bubbles escape from the solution, turn on the electrospinning device, set the positive voltage of the electrostatic field to 8kv, the negative voltage to 3kv, the collection roller speed to 110rpm, the distance between the spinning nozzle and the collection roller to 19cm, and the spinning time to 3h, to obtain a pressure-induced transparent micro-nano fiber film;

[0057] Step S3. Prepare a color film or fluorescent film substrate, and prepare a separate pressure-induced color-changing material by using the lamination method to combine the micro-nano fiber film obtained in step S2 with the substrate. The preparation method of the cesium lead bromide fluorescent film substrate is as follows: dissolve cesium bromide and lead bromide in polymethyl methacrylate and N,N-dimethylformamide (25%) respectively, and control the concentration of cesium bromide and lead bromide to be 1%-5%, and mix them thoroughly; take a cleaned glass sheet and place it on the adsorption table of a high-speed spin coater, preheat the mixed solution to 70°C, and then drop a small amount of the solution onto the glass sheet and spin it at high speed to obtain a spin-coated film; transfer the spin-coated film to a hot stage at 80°C, and anneal for 2 min. The volatilization of N,N-dimethylformamide induces the formation of cesium lead bromide nanocrystals, thereby obtaining a uniform green fluorescent cesium lead bromide film.

[0058] Step S4. Use the mask photolithography method established in the laboratory to prepare a mold with a surface microstructure, wherein the microstructure is a strip pattern, which is used to obtain a pressure monitoring resolution.

[0059] Step S5. Use software such as Solidworks to model and combine 3D printing to build a ring-shaped uniform light source (ultraviolet light and sunlight) for obtaining a two-dimensional pressure distribution map.

[0060] Example 5: A method for visualizing and monitoring the pressure distribution of a pressure-induced transparent micro-nano fiber film, comprising the following steps:

[0061] S1. Add 3g of polyvinylidene fluoride with a molecular weight of 15000g / mol to 20g of organic solvent, wherein the organic solvent is obtained by mixing 7.5g of N,N-dimethylformamide and 3.5g of acetone, and heating to 70°C. Mix uniformly at a stirring speed of 260rpm to obtain a polymer solution A;

[0062] S2. Add the polymer solution A to a diameter of 10cm electrospinning injector at a injection rate of 1.2mL / h, push the injector piston until no bubbles escape from the solution, turn on the electrospinning device, set the positive voltage of the electrostatic field to 8kv, the negative voltage to 3kv, the collection drum speed to 120rpm, the distance between the spinning nozzle and the collection drum to 20cm, and the spinning time to 2h, to obtain a pressure-induced transparent micro-nano fiber film;

[0063] S3. Prepare a color film or fluorescent film substrate, and prepare a separated pressure-induced chromic material by using the lamination method with the micro-nano fiber film obtained in step S2 and the substrate, wherein the preparation method of the cesium lead bromide fluorescent film substrate is as follows: dissolve cesium bromide and lead bromide in polymethyl methacrylate and N,N-dimethylformamide (25%) respectively, and control the concentration of cesium bromide and lead bromide to be 1%-5%, and mix them thoroughly; take a cleaned glass sheet and place it on the adsorption table of a high-speed spin coater, preheat the mixed solution to 70°C, take a small amount and drop it on the glass sheet, and then spin at high speed to obtain a spin coating film; transfer the spin coating film to a hot stage at 80°C, and anneal for 2 min, and the volatilization of N,N-dimethylformamide induces the formation of cesium lead bromide nanocrystals, thereby obtaining a uniform green fluorescent cesium lead bromide film;

[0064] S4. Use the mask photolithography method established in the laboratory to prepare a mold with a surface microstructure, wherein the microstructure is a strip pattern, which is used to obtain a pressure monitoring resolution;

[0065] S5. Use software such as Solidworks to model and combine 3D printing to build a ring-shaped uniform light source (ultraviolet light and sunlight) for obtaining a two-dimensional pressure distribution map.

[0066] Example 6: A large-scale preparation method of a pressure-induced transparent micro-nano fiber film for visual monitoring of interfacial pressure distribution, comprising the following steps:

[0067] S1. Add 3g of polycarbonate with a molecular weight of 15000g / mol to 20g of organic solvent, wherein the organic solvent is obtained by mixing 7.5g of dichloromethane and 3.5g of N,N-dimethylformamide, heated to 70°C, and mixed uniformly at a stirring speed of 260rpm to obtain a polymer solution A;

[0068] S2. Add the polymer solution A to a diameter of 10cm electrospinning injector at an injection rate of 1.2mL / h, push the injector piston until no bubbles escape from the solution, turn on the electrospinning device, set the positive voltage of the electrostatic field to 8kv and the negative voltage to 3kv, the rotating speed of the collection drum is 120rpm, the distance between the spinning nozzle and the collection drum is 20cm, and the spinning time is 2h, to obtain a pressure-induced transparent micro-nano fiber film;

[0069] S3. Prepare a color film or fluorescent film substrate, and prepare a separated pressure-induced chromic material by using the lamination method with the micro-nano fiber film obtained in step S2 and the substrate, wherein the preparation method of the cesium lead bromide fluorescent film substrate is as follows: dissolve cesium bromide and lead bromide in polymethyl methacrylate and N,N-dimethylformamide (25%) respectively, and control the concentration of cesium bromide and lead bromide to be 1%-5%, and mix them thoroughly; take a cleaned glass sheet and place it on the adsorption table of a high-speed spin coater, preheat the mixed solution to 70°C, take a small amount and drop it on the glass sheet, and then spin at high speed to obtain a spin coating film; transfer the spin coating film to a hot stage at 80°C, and anneal for 2 min, and the volatilization of N,N-dimethylformamide induces the formation of cesium lead bromide nanocrystals, thereby obtaining a uniform green fluorescent cesium lead bromide film;

[0070] S4. Use the mask photolithography method established in the laboratory to prepare a mold with a surface microstructure, wherein the microstructure is a strip pattern, which is used to obtain a pressure monitoring resolution;

[0071] S5. Use software such as Solidworks to model and combine 3D printing to build a ring-shaped uniform light source (ultraviolet light and sunlight) for obtaining a two-dimensional pressure distribution map.

[0072] Example 7: A visual monitoring interface pressure distribution pressure-induced transparent micro-nano fiber film large-scale preparation method, comprising the following steps:

[0073] S1. Add 3g of polyphenyl ether with a molecular weight of 15000g / mol to 20g of organic solvent, wherein the organic solvent is obtained from chloroform, heat to 70°C, mix uniformly at a stirring speed of 260rpm, and obtain a high molecular weight solution A;

[0074] S2. Add the high molecular weight solution A to a diameter of 10cm electrospinning injector at a injection rate of 1.2mL / h, push the injector piston until no bubbles escape from the solution, turn on the electrospinning device, set the positive voltage of the electrostatic field to 8kv and the negative voltage to 3kv, the collection drum rotating speed to 120rpm, the distance between the spinning nozzle and the collection drum to 20cm, and the spinning time to 2h, and obtain a pressure-induced transparent micro-nano fiber film;

[0075] S3. Prepare a color film or fluorescent film substrate, and prepare a separated pressure-induced chromic material by using the micro-nano fiber film obtained in step S2 and the substrate by using a lamination method, wherein the preparation method of the cesium lead bromide fluorescent film substrate is as follows: dissolve cesium bromide and lead bromide in polymethyl methacrylate and N,N-dimethylformamide (25%) respectively, and the concentration of cesium bromide and lead bromide is controlled to be 1%-5%, and then mix them thoroughly; take a cleaned glass sheet and place it on the adsorption table of a high-speed spin coater, preheat the mixed solution to 70°C, take a small amount of the solution and drop it on the glass sheet, and then spin it at high speed to obtain a spin coating film; transfer the spin coating film to a hot stage at 80°C, and anneal for 2 min, and the volatilization of N,N-dimethylformamide induces the formation of cesium lead bromide nanocrystals, so that a uniform green fluorescent cesium lead bromide film is obtained;

[0076] S4. Use the mask photolithography method established in the laboratory to prepare a mold with a surface microstructure, wherein the microstructure is a strip pattern, which is used to obtain a pressure monitoring resolution;

[0077] S5. Use software such as Solidworks to model and combine 3D printing to build a ring-shaped uniform light source (ultraviolet light and sunlight) for obtaining a two-dimensional pressure distribution map.

[0078] Comparative Example 1:

[0079] This comparative example is a commercialized Fujifilm pressure-sensitive paper, which is purchased from Taobao, the brand is FUJIFILM, the pressure detection range is 0-300 MPa, the resolution is greater than 100 μm, and the actual measured resolution is between 100-200 μm.

[0080] Comparative Example 2:

[0081] This comparative example is compared with Example 1 only by increasing the spinning time to 4 h to obtain a micro-nano fiber film, and the thickness thereof is measured to be 320 μm.

[0082] Comparative Example 3:

[0083] This comparative example is compared with Example 1 only by adjusting the concentration of the polymer solution A and the electrospinning parameters to obtain a layer-by-layer constructed film with larger micro-nano fiber diameter, and the scanning electron microscope result shows that the diameter thereof is about 4 μm, and the thickness of the obtained film is about 100 microns.

[0084] Comparative Example 4:

[0085] This comparative example is compared with Example 1 only by replacing the polymer used with elastic polyvinyl alcohol, and the solvent is water, the dissolution condition is 90°C stirring for 2 h, and then the micro-nano fiber film is prepared by electrospinning.

[0086] Performance test:

[0087] Performance test of pressure-induced transparent micro-nano fiber film:

[0088] The glass sheet with a striped micro-scale pattern was placed on the pressure-induced transparent micro-nano fiber film prepared in Examples 1-7 and Comparative Examples 1-4, and the film was placed on a mirror substrate, and pressure testing was performed using a universal testing machine, with a test pressure of 800 N (the pressure value varies according to the modulus of the polymer) and a holding time of 20 s, and the film was removed and observed using a scanning electron microscope;

[0089] Transparency performance test:

[0090] The pressure-induced transparent micro-nano fiber films prepared in Examples 1-7 and Comparative Examples 1-4 were placed in the middle of the mirror pressure head, and pressure testing was performed using a universal testing machine at a set pressure, and the change in transparency was observed under a microscope combined with a ring light source;

[0091] Transparency performance test after bonding with a substrate:

[0092] 2 g of PMMA and 5 g of N,N-dimethylformamide were mixed to obtain an organic solvent, and cesium bromide and lead bromide were dissolved in the organic solvent, respectively, with a concentration of cesium bromide of 2% and a concentration of lead bromide of 5%, and the two solutions were mixed uniformly and heated to 60-70°C, 1-2 mL of which was dropped onto a cleaned glass sheet and rotated at high speed to obtain a spin-coated film, and the spin-coated film was transferred to a hot stage at 70-80°C and annealed for 2-3 min to obtain a cesium lead bromide film;

[0093] The pressure-induced transparent micro-nano fiber films prepared in Examples 1-7 and Comparative Examples 1-4 were subjected to a set pressure using a universal testing machine, and the pressure-induced transparent ultra-thin film was then placed on the cesium lead bromide film and bonded, and microscope images were taken under daylight and ultraviolet light excitation to obtain the transparency difference rate;

[0094] Resolution performance test:

[0095] The pressure-induced transparent micro-nano fiber films prepared in Examples 1-7 and Comparative Examples 1-4 were combined with the cesium lead bromide film to obtain a split pressure-induced color-changing film, and a set pressure was applied on a universal testing machine, and the film was removed and processed by a computer to obtain a resolution image and resolution.

[0096] Pressure detection range test;

[0097] The pressure-induced transparent micro-nano fiber films prepared in Examples 1-7 and Comparative Examples 1-4 were subjected to a certain pressure using a mirror pressure head on a universal testing machine, with a pressure range of 0-2000 N, and the pressure detection range of different micro-nano fiber films was detected.

[0098] Table 1

[0099]

[0100]

[0101] Data analysis:

[0102] As can be seen from Table 1, the visual monitoring interface pressure distribution piezochromic micro-nano fiber film prepared by the present application has higher resolution and greater transparency difference rate. This may be because the high polymer solution A and electrospinning parameters are controlled, so that the obtained micro-nano fiber film has lower thickness (20-60 μm) and lower internal fiber diameter (0.5-2.0 μm), thereby obtaining smaller pore size and higher porosity, and the scattering of light and the change of porosity are linearly related. The film with higher porosity and smaller pore size can sensitively respond to changes in different pressures, thereby having higher resolution and transparency difference rate.

[0103] Comparative Example 1 is a commercialized Fuji pressure paper, and its piezochromic principle is to fill the inside with dye-containing microcapsules. The color changes after the capsule is broken under pressure. The diameter of the microcapsule is microns, which limits the resolution of this structure itself, and the actual measured resolution is greater than 100 μm, which poses a challenge to high-resolution pressure distribution imaging. Comparative Example 2, compared with Example 1, only increases the spinning time to 4 h. The long spinning time results in a higher thickness of the obtained spinning film. The advantage of the present application is that the film itself is thin (which can be as low as 20 μm), which makes the entire pressure direction of the film under pressure to be subjected to uniform pressure, so that the pore structure gradually disappears as a whole, inducing changes in the light scattering path, thereby obtaining higher resolution. However, when the thickness of the film is higher, the local change of the pore in the pressure direction is difficult to cause the light scattering path to change completely, resulting in lower resolution. Comparative Example 3, compared with Example 1, only adjusts the diameter of the micro-nano fiber film inside the fiber. The larger diameter makes the modulus higher, thereby increasing the pressure detection range, but the thickness increases slightly, which makes the resolution decrease. Comparative Example 4, compared with Example 1, only changes the high polymer used to elastic and hydrophilic polyvinyl alcohol, and the obtained micro-nano fiber film does not have obvious piezochromic phenomenon. This is mainly because the polyvinyl alcohol fiber inside the film has high elasticity, and the deformation caused by pressure is mainly elastic deformation. After the external force is removed, the deformation recovers, resulting in lower change rate of porosity, which is difficult to induce changes in the light scattering path. The internal pores make the light multiple scattering inside the film, which is difficult to pass through the film.

[0104] It should be understood by those skilled in the art that the above discussion of any of the embodiments is merely exemplary and is not intended to suggest that the scope of the present application is limited to these examples; under the idea of the present application, the above embodiments or technical features among different embodiments can also be combined, the steps can be implemented in any order, and there are many other changes of different aspects of the present application as described above. In order to be brief, they are not provided in detail.

[0105] The present application is intended to cover all such alternatives, modifications, and variations as fall within the broad scope of the appended claims. Accordingly, any and all such alternatives, modifications, equivalents, improvements and the like are intended to be encompassed by the present application.

Claims

1. A large-scale preparation method of pressure-induced transparent micro-nano fiber film for visual monitoring of interface pressure distribution, characterized in that: The following steps are involved: Step S1. Adding a plastic polymer to an organic solvent, heating and stirring to mix uniformly to obtain a polymer solution A; Step S2. Testing and recording the viscosity and surface tension of polymer solution A, and adjusting the diameter of the electrospun fibers in combination with the electrospinning parameters, thereby adjusting the pressure detection range of the micro-nano fiber film; Step S3. Add polymer solution A to the electrospinning syringe, push the syringe plunger until no bubbles escape from the solution, turn on the electrospinning apparatus, set the spinning parameters, and obtain a layered, opaque, white micro-nanofiber film. Step S4. Prepare a color film or fluorescent film substrate, and laminate the micro-nano fiber film and the substrate to prepare a separate piezochromic material. The preparation method of the cesium lead bromide fluorescent film substrate is as follows: dissolve cesium bromide and lead bromide in 25% polymethyl methacrylate in N,N-dimethylformamide, with the concentration of cesium bromide and lead bromide controlled to 1%-5%, and mix them thoroughly to obtain a mixed solution; take a clean glass slide, place it on the adsorption table of a high-speed spin coater, preheat the mixed solution to 70°C, take a small amount and drop it on the glass slide, and then spin it at high speed to obtain a spin-coated film; transfer the spin-coated film to an 80°C hot plate and anneal for 2 minutes; Step S5. Using a masked photolithography method established in the laboratory to prepare a mold with a surface microstructure, wherein the microstructure is a stripe pattern, the photolithography mask and etching conditions are controlled to obtain a mold with different stripe spacings to obtain pressure monitoring resolution; Step S6. Using Solidworks software modeling combined with 3D printing, a ring-shaped uniform light source of ultraviolet light and sunlight is constructed to obtain a two-dimensional pressure distribution map; The high molecular polymer in step S1 is any one of polyacrylonitrile, polymethyl methacrylate or polyvinyl butyral plastic polymer; The organic solvent in step S1 is obtained by mixing N,N-dimethylformamide and acetone in a mass ratio of 6.5-7.5:2.5-3.5; The mass ratio of the polymer compound to the organic solvent in step S1 is 1-3:7-20; The diameter of the electrospinning syringe in step S3 is 8-10 cm, and the injection speed is 0.8-1.2 mL / h; The spinning parameters in step S3 include a positive voltage of 6-15 kV, a negative voltage of 2-3 kV, a collection drum speed of 80-200 rpm / min, a spacing between the spinning nozzle and the collection drum of 10-20 cm, and a spinning time of 1-5 h. The thickness of the micro-nano fiber film in step S3 is 20-60 μm.

2. The method for large-scale preparation of pressure-induced transparent micro-nano fiber film for visual monitoring of interface pressure distribution according to claim 1 is characterized in that: The polymer in step S1 is a plastic hydrophobic polymer with a molecular weight of 10 4 -10 5 g / ml.

3. The method for large-scale preparation of pressure-induced transparent micro-nano fiber film for visual monitoring of interface pressure distribution according to claim 1, characterized in that: The temperature during the heating and stirring in step S1 is 50-70° C., and the stirring rate is 260-320 rpm.

Images