Preparation method of anisotropic stress luminescent elastomer film and anisotropic stress luminescent elastomer film

Abstract

The invention belongs to the technical field of stress luminescent materials, and provides a preparation method of an anisotropic stress luminescent elastomer film and the anisotropic stress luminescent elastomer film. The existing stress luminescent material generally has bottleneck problems of limited luminous intensity and the like, which seriously restricts the practical application of the stress luminescent material. According to the invention, the anisotropic stress luminescent elastomer film is prepared from the stress luminescent particles and polysiloxane through an electrorheological effect, so that the stress luminescent intensity is increased. The anisotropic stress luminescent elastomer film is constructed, a new thought is provided for development of high-performance stress luminescent materials, an established stress luminescent intensity enhancement mechanism provides an important theoretical basis for development of novel intelligent sensing materials, and the anisotropic stress luminescent elastomer film has wide application prospects in the fields of industrial nondestructive testing, flexible electronic devices and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of stress luminescent materials, and particularly relates to a preparation method of an anisotropic stress luminescent elastomer film and the anisotropic stress luminescent elastomer film. BACKGROUND

[0002] Mechanoluminescence (ML) materials are a class of intelligent materials that directly excite light radiation by mechanical energy. With its characteristics of passive self-driving, real-time response and high sensitivity, it shows important application prospects in intelligent sensing, structural health monitoring, energy conversion, dynamic stress sensing, wearable devices and other fields. The significant progress of luminescent materials has promoted the development of science and technology. Mechanical stress is the most common external stimulus, so mechanical light conversion materials have broad prospects in scientific and engineering applications. Most ML materials are micron to millimeter solid particles, which cannot be used alone and need to be prepared into composite materials with other carriers. The advantages of such composite materials include formability and processability. ML particles do not move significantly when subjected to mechanical action, and the composite material transmits the applied stress to the ML particles through the soft matrix, allowing brittle crystalline particles to withstand greater mechanical impact. Composite materials have excellent processing performance, and flexibility makes it easy for the composite material to adhere to complex surfaces for pressure sensing. However, the existing ML materials prepared into composite materials with soft matrices have the following problems: ML particles are randomly and uniformly distributed in the soft matrix, so when an external load is applied, the load on the ML particles is not concentrated, resulting in weak luminescence intensity.

[0003] Traditional stress luminescent materials (such as isotropic elastomer films) are prepared by directly mixing stress luminescent phosphor (such as CaZnOS:Mn 2+ ) with a polymer matrix (such as PDMS) and curing, forming a disordered composite film. The random distribution of particles leads to discontinuous stress transmission path, low spatial coupling efficiency of piezoelectric effect and luminescent center, and serious energy loss. The core defect is that the random distribution of particles leads to low stress transmission efficiency, the mechanical stress cannot be transmitted to the luminescent center through a continuous path, a large amount of energy is lost in the matrix deformation or particle friction, and the luminescence intensity is significantly limited; the mechanical energy-light energy conversion efficiency is low, the disordered structure leads to low spatial coupling efficiency of piezoelectric effect (from CaZnOS matrix) and Mn 2+ luminescent center, and only part of the mechanical energy is effectively converted into light energy.

[0004] Therefore, there is an urgent need to develop a preparation method of an anisotropic stress luminescent elastomer film to solve the problems of low efficiency and uncontrollability caused by the random distribution of particles in traditional stress luminescent films. SUMMARY

[0005] The application provides a preparation method of an anisotropic stress luminescent elastomer film and the anisotropic stress luminescent elastomer film to at least solve one of the problems in the related art.

[0006] The application aims to provide a preparation method of an anisotropic stress luminescent elastomer film, which applies an electric field in a polysiloxane curing process through an electric field induced particle directional arrangement technology, so that stress luminescent fluorescent particles form a chain or columnar ordered structure along the direction of the electric field, a continuous stress transmission path is constructed, the piezoelectric electric field direction is aligned with the luminescent center direction in the chain structure, and the ordered arrangement structure amplifies the local piezoelectric electric field intensity through the piezoelectric effect.

[0007] To achieve the above-mentioned purpose, the application provides the following technical scheme:

[0008] The application provides a preparation method of an anisotropic stress luminescent elastomer film, which includes the following steps:

[0009] (1) uniformly mixing polysiloxane and a curing agent to obtain a mixture;

[0010] (2) uniformly mixing stress luminescent particles into the mixture to obtain an elastomer precursor;

[0011] (3) pouring the elastomer precursor into a curing mold and placing it in a vacuum drying box to remove the bubbles generated in the mixing process;

[0012] (4) placing the curing mold after removing the bubbles on a heating plate for curing; and applying an electric field on the upper and lower metal plates of the curing mold;

[0013] (5) taking out the cured product to obtain an anisotropic stress luminescent elastomer film.

[0014] Preferably, the polysiloxane is at least one of polydimethylsiloxane, polydiethylsiloxane and polymethylphenylsiloxane.

[0015] Preferably, the polysiloxane is polydimethylsiloxane; and the polydimethylsiloxane is PDMS.

[0016] Preferably, the mass ratio of the polysiloxane to the curing agent is 10:0.2-2.

[0017] Preferably, the mass ratio of the polysiloxane to the curing agent is 10:1.

[0018] Preferably, the mass ratio of the stress luminescent particles to the polysiloxane is 1-10:10.

[0019] Preferably, the mass ratio of the stress luminescent particles to the polysiloxane is 2-8:10.

[0020] Preferably, the mass ratio of the stress luminescent particles to the polysiloxane is 0.2, 0.4, 0.6, or 0.8.

[0021] Preferably, the curing mold is composed of two metal plates and an insulating plastic ring in the middle. Figure 1

[0022] Preferably, the curing mold has a cylindrical space in the middle after being closed.

[0023] Preferably, the cylindrical space has a thickness of 0.5-5 mm and a diameter of 10-100 mm.

[0024] Preferably, the cylindrical space has a thickness of 1 mm and a diameter of 40 mm.

[0025] Preferably, the temperature of the heating plate is 50-70℃, and the curing time is 2-3 h.

[0026] Preferably, the temperature of the heating plate is 60℃.

[0027] Preferably, an electric field is applied for 10-20 min before heating and curing, and the heating and the application of the electric field are continued until the end of the curing after the formation of chains.

[0028] Preferably, an electric field is applied for 15 min before heating and curing.

[0029] Preferably, the electric field is a direct current electric field.

[0030] Preferably, the electric field is a direct current electric field, and a direct current high-voltage power supply is used to apply the direct current electric field to the upper and lower metal plates of the curing mold. Figure 2

[0031] Preferably, when the electric field is a direct current electric field, the intensity of the applied electric field ranges from 0 to 2000 V / mm.

[0032] Preferably, when the electric field is a direct current electric field, the intensity of the applied electric field ranges from 300 to 900 V / mm.

[0033] Preferably, when the electric field is a direct current electric field, the intensity of the applied electric field is 300 V / mm, 600 V / mm, or 900 V / mm.

[0034] Preferably, the anisotropic stress luminescent elastomer film has a thickness of 0.5-5 mm and a diameter of 10-100 mm.

[0035] ​​Preferably, the anisotropic stress luminescent elastomer film has a thickness of 1 mm and a diameter of 40 mm; the anisotropic stress luminescent elastomer film is as shown in Fig. Figure 3 (Left).

[0036] The stress luminescent particles of the present application are prepared by a conventional high-temperature solid-phase reaction method.

[0037] Preferably, the stress luminescent particles are CaZnOS:Mn 2+ .

[0038] Preferably, the stress luminescent particles are CaZnOS:1% Mn 2+ .

[0039] Preferably, the method for preparing the stress luminescent particles comprises the following steps:

[0040] CaCO3, ZnS, and MnCO3 powders are weighed in stoichiometric proportions, mixed and ground together with a sintering aid and a dispersant, heated and stirred, crushed, to obtain a precursor powder, sintered, ground, to obtain stress luminescent particles.

[0041] Preferably, the method for preparing the stress luminescent particles CaZnOS:1% Mn 2+ comprises the following steps:

[0042] (1) CaCO3, ZnS, and MnCO3 powders are weighed in stoichiometric proportions;

[0043] (2) LiNO3 is taken as a sintering aid at 0.05-0.2% of the total mass of the above raw materials;

[0044] (3) an appropriate amount of anhydrous ethanol is used as a dispersant, and all raw materials are placed in a mortar for sufficient grinding and mixing;

[0045] (4) all raw materials are transferred to a beaker and placed on a magnetic heating stirrer at 70-80°C for heating and stirring until all liquid anhydrous ethanol is discharged;

[0046] (5) the dried powder in the beaker is crushed with a sample spoon to obtain a precursor powder, and then the precursor powder is transferred to a corundum crucible;

[0047] (6) the crucible containing the precursor powder is transferred to a horizontal tube furnace, sintered at 1000-1200°C for 3-5h in an inert atmosphere, cooled to room temperature, and then ground thoroughly to obtain stress luminescent particles.

[0048] Preferably, the inert atmosphere is at least one of Ar, He, and N2.

[0049] Preferably, the stress luminescent particles have a chemical formula of CaZn 1～XMn X OS, where x = 0.01.

[0050] CaZnOS:Mn 2+ is a stable stress luminescence material, which has potential application value in the fields of anti-counterfeiting, stress distribution (imaging, visualization, sensing), etc. The ML performance of the quaternary piezoelectric material CaZnOS can be developed for mechanical-to-optical energy conversion and optical sensing. To monitor the distribution of applied force and visualization, a flexible composite film is prepared, which is composed of a mixture of CaZnOS:1% Mn 2+ and polydimethylsiloxane (184 PDMS), which is sealed by a polyethylene glycol diformate (PET) film. According to the distribution of particles in the matrix, the elastomer can be divided into anisotropic and isotropic elastomer films. In the isotropic elastomer, the particles are randomly distributed in the matrix; in the anisotropic stress luminescence elastomer film, the particles are arranged along the direction of the electric field, and the chain structure is still retained in the matrix after the matrix is well cured. In the present application, 184 PDMS and a curing agent are selected as the dispersant, and the stress luminescence fluorescent powder is selected as the dispersed particles, and isotropic and anisotropic stress luminescence elastomer films are prepared. The stress luminescence performance of the films is compared, and the internal mechanism is explored through the cross-sectional morphology of the films. Generally, a lower elastic modulus of the elastic matrix can obtain a higher electrorheological effect, and the mobility of the particles is better, which helps to improve the electrorheological effect.

[0051] When the stress luminescence fluorescent particles form a mixture with the polymer 184 PDMS, the particles are randomly distributed in the PDMS without an applied electric field; when an external electric field is applied, the solid particles are polarized and attracted to each other, and arranged into a chain structure along the direction of the electric field. When the external electric field is large enough, the chain structures will approach each other to form a columnar structure.

[0052] The currently generally accepted mechanism of stress luminescence material is the process of trap carrier de-trapping caused by piezoelectricity under the action of load, so in the stress luminescence material, the trap produced by doping luminescent ions in the matrix is often used to adjust the stress luminescence performance, such as improving the stress luminescence intensity by doping different luminescent ions. The method provided in the embodiments of the present application for enhancing the stress luminescence intensity by applying an electric field to the stress luminescence material and the PDMS during the curing process is completely different from the existing mechanism for adjusting the luminescence intensity of the stress luminescence material.

[0053] As Figure 4As shown, after the stress luminescent particles form chain or columnar structure under the action of electric field, under the action of external force, the particles are subjected to more force in the vertical direction, and the stress luminescent particles undergo space charge separation, and when released, they release in the form of light, and the increase in light intensity can be attributed to the compression between the particles, which enables more photons to be released, thereby enhancing the light emission intensity. The light emission process is as follows: through the bidirectional coupling effect between piezoelectricity and photoexcitation characteristics, the piezoelectric effect triggers the conversion from mechanical stress to visible light emission, and the elastic matrix (such as PDMS) can transmit stress or tension to the embedded stress luminescent particles and trigger flexible ML.

[0054] The application also provides an anisotropic stress luminescent elastomer film prepared by the above method.

[0055] Preferably, the stress luminescent particles are orderly arranged in a chain or columnar structure in the polysiloxane.

[0056] Basic mechanism of chain or columnar structure formation:

[0057] Interaction between particles under external electric field, where dielectric particles suspended in insulating polymer obtain induced dipole moment, resulting in dipole-dipole interaction force between two particles, and particles tend to form the lowest energy structure, i.e. when the electric field strength increases, chains will be formed first, and then columnar structures will be formed; the application of an external electric field changes the uniform system into a non-uniform system with alignment.

[0058] Schematic diagram of the mechanism of action of particles under electric field (as shown in Figure 5 Without electric field, particles are randomly distributed in the system, and when electric field is applied, particles arrange to form chain or columnar structure under the action of dipole interaction, and based on the electrorheological effect, an electrorheological elastomer (ERE) that responds to electric field can be designed.

[0059] Electric field-induced structure regulation: stress luminescent particles are directionally arranged by dielectric force to form a continuous stress transmission structure, solving the problem of energy loss in disordered structure.

[0060] Piezoelectric-light emission synergistic enhancement: ordered arrangement optimizes the spatial coupling between piezoelectric phase and light emission center, and utilizes the overall piezoelectric field to excite Mn 2+ Comparison of stress transmission paths between traditional disordered structure and the ordered structure of the application.

[0061] The application significantly improves the stress luminescent intensity of the stress luminescent elastomer film compared with the existing stress luminescent elastomer film through the electric field-assisted curing process.

[0062] Preferably, the anisotropic stress luminescent elastomer film adopts an electric field-assisted curing process to induce directional arrangement of particles during the curing process of the polysiloxane matrix.

[0063] Preferably, the microstructure of the anisotropic stress-luminescent elastomer film has a chain-like or columnar ordered arrangement; the microstructure is formed by applying an electric field; the microstructure can significantly improve stress transmission efficiency and luminescence intensity.

[0064] This invention achieves ordered particle arrangement and performance regulation through an electric field-assisted curing process.

[0065] Preferably, the present invention also provides a method for regulating the performance of the anisotropic stress-luminescent elastomer film, which is achieved by synergistically regulating the electric field strength and particle concentration.

[0066] Existing technology: Random particle dispersion → discontinuous stress transmission path → inefficient luminescence.

[0067] This invention: Electric field-induced chain arrangement → continuous path → high-efficiency stress-light energy conversion → high-efficiency light emission.

[0068] The present invention also provides the application of the anisotropic stress-luminescent elastomer film based on the low stress response of the ordered structure in the fields of micro-strain detection, flexible sensing, flexible electronic devices, bio-imaging, flexible display, and wearable devices.

[0069] Stress sensor: The chain-like structure formed may cause changes in stress luminescence performance, such as luminescence intensity. By monitoring this change, the anisotropic stress luminescence elastomer film can be used on the surface of building structures and mechanical parts. When subjected to load, the chain-like structure of stress luminescence particles formed will change accordingly. The magnitude and distribution of stress can be judged by the strength of the stress luminescence signal.

[0070] Display technology: By utilizing the chain-like structure changes of stress-emitting particles under an electric field, the light emission can be regulated. By controlling the intensity and direction of the electric field, the intensity of the stress-emitting particles in the chain-like structure can be changed. This technology has the characteristics of not requiring an excitation source and low power consumption, and has potential application prospects in the fields of flexible displays and wearable devices.

[0071] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:

[0072] 1. Traditional isotropic films have low luminescence intensity due to the random and uniform distribution of particles. This invention achieves controllable directional arrangement of stress-luminescent particles in an elastomer through an electric field-assisted curing process, breaking through the limitation of random particle distribution in traditional disordered composite films.

[0073] 2. This invention employs electric field-induced particle orientation alignment technology. By applying an external electric field, the stress-luminescent particles (CaZnOS:1%Mn) are oriented and aligned. 2+In the 184PDMS matrix, a chain-like or columnar ordered structure is formed along the electric field direction, which significantly improves stress transfer efficiency and luminescence intensity.

[0074] 3. Compared with stress-luminescent composite films without an applied electric field, the preparation method of the anisotropic stress-luminescent elastomer film of the present invention has the following advantages:

[0075] ① Enhance luminescence intensity, electric field induces ordered arrangement to enhance stress-luminescence conversion efficiency, apply electric field to induce stress luminescent particles to form chain or column structure, optimize transmission path.

[0076] ② Reduce costs by eliminating the need for complex pre-radiation or packaging processes and achieving high performance directly through electric field control.

[0077] ③ Improve efficiency, enhance the mechanical energy to light energy conversion efficiency, and reduce system energy consumption. Attached Figure Description

[0078] Figure 1 A curing mold for elastomer films;

[0079] Figure 2 This is a circuit connection diagram for the curing process of anisotropic stress-luminescent elastomer films.

[0080] A schematic diagram showing the connection of a DC voltage source, multimeter, heating plate, and mold during the curing process of anisotropic stress-luminescent elastomer film.

[0081] Figure 3 These are physical images of anisotropic stress-luminescent elastomer films (left) and isotropic elastomer films (right);

[0082] Figure 4 This is a schematic diagram of the ML mechanism in a stress-luminescent crystal, where M represents the space charge separation caused by mechanical stimulation of the material, and the release mode represents the energy ultimately released in the form of photon emission.

[0083] Figure 5 This is a diagram illustrating the mechanism of particle interaction under an electric field.

[0084] Figure 6 CaZnOS:1%Mn 2+ Comparison of XRD patterns with standard cards;

[0085] Figure 7 CaZnOS:1% Mn 2+ SEM image;

[0086] Figure 8 SEM images of the side cross section of an elastomer film cured without an electric field (left) and the side cross section of an elastomer film cured under an electric field (right) (observed at 250 μm);

[0087] Figure 9 Optical microscope images (left) of a cross-section of an elastomer film cured without an electric field and a cross-section of an elastomer film cured under an electric field (right) (250 μm);

[0088] Figure 10 Optical microscope images (left) of a cross-section of an elastomer film cured without an electric field and a cross-section of an elastomer film cured under an electric field (right) (250 μm);

[0089] Figure 11 The crystal structure diagram of CaZnOS;

[0090] Figure 12 CaZnOS:1% Mn 2+ EDS spectrum distribution of various elements (S, O, Zn, Ca, Mn) in China;

[0091] Figure 13 A device for testing stress luminescence;

[0092] Figure 14 For stress-luminescent particles: PDMS mass ratio = 0.2, applied electric fields are E = 0 V / mm, E = 300 V / mm, E = 600 V / mm, E = 900 V / mm. (a) Impact luminescence diagram of cured elastomer film. (b) Average brightness of impact stress luminescence intensity of the front (top) and (c) bottom (bottom) surfaces of the elastomer film as a function of electric field.

[0093] Figure 15 For stress-luminescent particles: PDMS mass ratio = 0.4, applied electric fields are E = 0 V / mm, E = 300 V / mm, E = 600 V / mm, E = 900 V / mm. (a) Impact luminescence diagram of cured elastomer film. (b) Average brightness of impact stress luminescence intensity of the front (top) and (c) bottom (bottom) surfaces of the elastomer film as a function of electric field.

[0094] Figure 16 For stress-luminescent particles: PDMS mass ratio = 0.6, applied electric fields are E = 0 V / mm, E = 300 V / mm, E = 600 V / mm, E = 900 V / mm. (a) Impact luminescence diagram of cured elastomer film. (b) Average brightness of impact stress luminescence intensity of the front (top) and (c) bottom (bottom) surfaces of the elastomer film as a function of electric field.

[0095] Figure 17For stress-luminescent particles: PDMS mass ratio = 0.8, applied electric fields are E = 0 V / mm, E = 300 V / mm, E = 600 V / mm, E = 900 V / mm. (a) Impact luminescence diagram of cured elastomeric film. (b) Average brightness of impact stress luminescence intensity of the elastomeric film as a function of electric field on the front (top) and (c) bottom (bottom) surfaces of the elastomeric film. Detailed Implementation

[0096] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0097] Preparation Example 1

[0098] Stress-luminescent particles CaZnOS:1%Mn 2+ The preparation method includes the following steps:

[0099] The stress-luminescent particles CaZnOS:1%Mn used in the following examples 2+ The preparation is carried out using a traditional high-temperature solid-state reaction method, as detailed below:

[0100] (1) Weigh CaCO3, ZnS, and MnCO3 powders according to their stoichiometric ratios;

[0101] (2) Take 0.1% of the total mass of the above raw materials as a sintering aid;

[0102] (3) Using an appropriate amount of anhydrous ethanol as a dispersant, all raw materials are placed in a mortar and thoroughly ground and mixed.

[0103] (4) Transfer all raw materials to a beaker and place it on a magnetic stirrer at 75°C for heating and stirring until all liquid (anhydrous ethanol) is discharged.

[0104] (5) Crush the dried powder in the beaker with a sample spoon to obtain precursor powder, and then transfer the precursor powder to the corundum crucible.

[0105] (6) The crucible containing the precursor powder was transferred to a horizontal tube furnace and sintered at 1100℃ for 4 hours in an Ar atmosphere. After cooling to room temperature, it was thoroughly ground to obtain stress-luminescent particles with the general chemical formula CaZn. 1～X Mn X OS, where x = 0.01.

[0106] During the sintering process, 0.1% of the total mass of raw materials LiNO3 is generally added to ensure that the doped luminescent ions can completely enter the matrix. However, the amount added should not be too much. Generally, when the amount added is 0.5%, the sintered stress-luminescent phosphor will all clump together and be difficult to grind into powder. When 0.1% of LiNO3 is added, it can be easily ground apart, and the powder is loose, has a low density, and emits light well.

[0107] Example 1

[0108] This embodiment provides a method for preparing anisotropic stress-luminescent elastomer thin films, including the following steps:

[0109] (1) Mix 184PDMS and curing agent (platinum-catalyzed hydrogen-containing siloxane crosslinking agent) at a mass ratio of 10:1 to obtain a mixture;

[0110] (2) Stress-luminescent particles CaZnOS:1%Mn 2+ The mixture was added to the mixture and mixed evenly to obtain the elastomer precursor; the mass ratios of the stress-luminescent particles to PDMS were 0.2, 0.4, 0.6, and 0.8, respectively.

[0111] (3) Pour the above-mentioned elastomer precursor into a curing mold and place it in a vacuum drying oven to remove air bubbles generated during the mixing process; the curing mold consists of two metal plates, an upper and a lower one, and an insulating plastic ring in the middle, as shown in the image. Figure 1 As shown; after the curing mold is closed, a 1mm thick cylindrical space is formed in the middle, which is the space for filling the precursor;

[0112] (4) Place the cured mold, after removing air bubbles, on a heating plate at 60°C and cure for 2.5 hours. Apply a DC electric field to the upper and lower metal plates of the cured mold using a DC high-voltage power supply (using an SL300 DC high-voltage power supply manufactured by SMEP AG, Inc., USA). Preferably, before heating and curing, apply the electric field for 15 minutes. After chain formation, heat the mold on the heating plate at 60°C and continue applying the electric field until curing is complete. The strengths of the applied electric fields are 300V / mm, 600V / mm, and 900V / mm, respectively. The circuit connection diagram during the curing process is shown below. Figure 2 As shown;

[0113] (5) After curing, remove the film with a punch to obtain an anisotropic stress-luminescent elastomer film. The elastomer film has a thickness of 1 mm and a diameter of 40 mm. The anisotropic stress-luminescent elastomer film is as follows: Figure 3 As shown on the left.

[0114] Comparative Example 1

[0115] This comparative example provides a method for preparing an isotropic elastomer film, comprising the following steps:

[0116] (1) Mix 184PDMS and curing agent at a mass ratio of 10:1 (platinum-catalyzed hydrogen-containing siloxane crosslinking agent) to obtain a mixture;

[0117] (2) Stress-luminescent particles CaZnOS:1%Mn 2+ The mixture was added to the mixture and mixed evenly to obtain the elastomer precursor; the mass ratios of the stress-luminescent particles to PDMS were 0.2, 0.4, 0.6, and 0.8, respectively.

[0118] (3) Place the above-mentioned uniformly mixed elastomer precursor into a circular mold (the mold will form a cylindrical space with a thickness of 1 mm in the middle), and place it in a vacuum drying oven to remove the air bubbles generated during the mixing process.

[0119] (4) Place the cured mold after removing air bubbles on a heating plate at 60°C and let it cure for 2-3 hours;

[0120] (5) After curing, remove the film with a punch to obtain an isotropic elastomer film. The thickness of the elastomer film is 1 mm and the diameter is 40 mm. A physical image of the isotropic elastomer film is shown below. Figure 3 As shown on the right.

[0121] This invention successfully prepared anisotropic stress-luminescent elastomer films and isotropic elastomer films. The main difference between the two lies in the distribution of stress-luminescent particles inside PDMS. In the isotropic elastomer film, the stress-luminescent particles are randomly and uniformly dispersed inside PDMS; in the anisotropic stress-luminescent elastomer film, the stress-luminescent particles are arranged in a chain-like or columnar structure along the electric field direction.

[0122] Performance testing

[0123] (1) Material structure characterization

[0124] CaZnOS:1%Mn was prepared by high-temperature solid-state reaction method. 2+ Through XRD (such as Figure 6 As shown, the crystal structure (the crystal structure of CaZnOS is as follows) can be confirmed. Figure 11 As shown), scanning electron microscope (e.g.) Figure 7 (As shown) Observe the microstructure, EDS (such as Figure 12 (As shown) Analyze the distribution of various elemental spectra.

[0125] (2) Verification of electric field-induced alignment

[0126] like Figure 3The image shows the appearance of the prepared anisotropic stress-luminescent elastomer film (left) and isotropic elastomer film (right). The prepared elastomer film is a circular sheet with a thickness of 1 mm and a diameter of 40 mm. From the appearance, it can be judged that the distribution of stress-luminescent particles inside changed after the electric field was applied. The surface of the elastomer film cured without an electric field showed no abnormalities, indicating that the stress-luminescent particles were randomly distributed in the cured elastomer film.

[0127] To clearly observe the particle distribution inside the elastomer film, this invention further uses an optical microscope and a scanning electron microscope to observe the particle distribution on the sides.

[0128] The particle distribution in anisotropic stress-luminescent elastomer films and isotropic elastomer films was observed using a Leica DMi8M upright microscope from the German Leica microsystem. The films were cut with a side section thickness of 1 mm using a dicing machine. The cut side section of the film was placed on a rectangular glass slide and then placed under the microscope. The eyepiece and objective lens of the microscope system were adjusted for focusing, the magnification was adjusted to 5x, and the aperture size was adjusted to control the amount of light entering. This allowed for clear observation of the particle distribution in the side sections of the prepared anisotropic stress-luminescent elastomer films and isotropic elastomer films, thus clarifying the overall particle distribution in PDMS.

[0129] The cross-sectional morphology of the elastomer film and the CaZnOS:1%MnO2 content were observed using a Hitachi SU8230 scanning electron microscope (SEM). 2+ Before observing the morphology of the particles, the elastomer film needs to be cut open with a blade. At this time, the cross-section of the 1mm thick film can be seen. The cut cross-section is attached to the sample stage with conductive tape and then sent into the SEM chamber. The voltage is adjusted for observation.

[0130] Microstructure observation: SEM (e.g.) Figure 8 (as shown) and optical microscopes (such as) Figure 9 , Figure 10 As shown, the side particle distribution structure of isotropic and anisotropic stress-luminescent elastomer films was observed, demonstrating the chain / column structure formed by the particles along the electric field direction.

[0131] (3) Stress luminescence performance test

[0132] This invention is tested through a free-fall impact experiment, and the device for testing stress luminescence is as follows: Figure 13 As shown.

[0133] According to the preparation method of the anisotropic stress-luminescent elastomer film described in Example 1, when the mass ratio of the stress-luminescent particles to PDMS is 0.2, the test results are as follows: Figure 14As shown; when the mass ratio of the stress-luminescent particles to PDMS is 0.4, the test results are as follows. Figure 15 As shown; when the mass ratio of the stress-luminescent particles to PDMS is 0.6, the test results are as follows. Figure 16 As shown; when the mass ratio of the stress-emitting particles to PDMS is 0.8, the test results are as follows. Figure 17 As shown.

[0134] It can be seen that, compared with isotropic elastomer films, the anisotropic stress-luminescent elastomer film prepared by this invention exhibits a significantly improved stress luminescence intensity. Through the above material structure characterization and performance testing, the feasibility of the technical solution adopted in this invention and its importance in achieving the technical effects are systematically demonstrated.

[0135] The above description represents the preferred embodiments of the present invention. It should be noted that, for those skilled in the art,

[0136] For those skilled in the art, without departing from the principles described in this invention, further work can be done.

[0137] Several improvements and refinements have been made, and these improvements and refinements should also be considered within the scope of protection of this invention.

Claims

1. A method for preparing an anisotropic stress-luminescent elastomer thin film, characterized in that, Includes the following steps: (1) Mix the polysiloxane and the curing agent evenly to obtain a mixture; (2) Add stress-luminescent particles to the mixture and mix evenly to obtain an elastomer precursor; (3) Pour the above-mentioned elastomer precursor into a curing mold; (4) Place the curing mold on a heating plate and heat it to cure; apply an electric field to the curing mold; (5) After curing, the film is removed to obtain an anisotropic stress-luminescent elastomer film.

2. The method for preparing anisotropic stress-luminescent elastomer thin film according to claim 1, characterized in that, During the curing process, an electric field is applied to induce the directional alignment of stress-emitting particles, which are then arranged in an orderly manner into chain-like or columnar structures within the polysiloxane.

3. The method for preparing anisotropic stress-luminescent elastomer thin film according to claim 1, characterized in that, Before heating and curing, an electric field is applied for 10 to 20 minutes. After the chains are formed, the product is heated on a heating plate and the electric field is applied until the curing is complete. The temperature of the heating plate is 50 to 70°C and the curing time is 2 to 3 hours.

4. The method for preparing anisotropic stress-luminescent elastomer thin film according to claim 1, characterized in that, The electric field is a direct current electric field.

5. The method for preparing anisotropic stress-luminescent elastomer thin film according to claim 4, characterized in that, The electric field is a DC electric field, and the intensity of the applied electric field ranges from 0 to 2000 V / mm; preferably, the intensity of the applied electric field ranges from 300 to 900 V / mm.

6. The method for preparing anisotropic stress-luminescent elastomer thin film according to claim 1, characterized in that, The mass ratio of the stress-emitting particles to the polysiloxane is 1 to 10:10; preferably, the mass ratio of the stress-emitting particles to the polysiloxane is 2 to 8:

10.

7. The method for preparing anisotropic stress-luminescent elastomer thin film according to claim 1, characterized in that, The mass ratio of the polysiloxane to the curing agent is 10:0.2-2; the stress-emitting particles are CaZnOS:Mn 2+ The method for preparing the stress-luminescent particles is as follows: weigh CaCO3, ZnS, and MnCO3 powders according to the stoichiometric ratio, grind and mix them together with sintering aids and dispersants, heat and stir, crush them to obtain precursor powder, and then sinter and grind them to obtain stress-luminescent particles.

8. The method for preparing anisotropic stress-luminescent elastomer thin film according to claim 1, characterized in that, The anisotropic stress-luminescent elastomer film has a thickness of 0.5–5 mm and a diameter of 10–100 mm.

9. The method for preparing anisotropic stress-luminescent elastomer thin film according to claim 1, characterized in that, The curing mold consists of two metal plates, an upper and a lower one, and an insulating plastic ring in the middle; an electric field is applied to the upper and lower metal plates of the curing mold.

10. An anisotropic stress-luminescent elastomer film, characterized in that, Prepared by the method according to any one of claims 1 to 9.

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