Crystalline photosensitive material and method for preparing wearable nanofiber fabric by using same

Abstract

The invention belongs to the technical field of photosensitive materials and nanofiber fabrics, and relates to a crystalline photosensitive material and a method for preparing a wearable nanofiber fabric by using the same, the method comprises the following steps: uniformly mixing ferrous sulfate heptahydrate, oxalic acid dihydrate, 2, 4, 6-tri (4-pyridine)-1, 3, 5-triazine and N, N-dimethylacetamide, adding phosphoric acid to adjust the pH value, carrying out solvothermal reaction, and carrying out vacuum drying to obtain the wearable nanofiber fabric. A crystalline photosensitive material is obtained; adding into a polyurethane / DMA (direct memory access) solution, and preparing the wearable nanofiber fabric by using an electrostatic spinning process. The fabric has the photochromic and photothermal conversion double photoresponse functions, the thermal state can be monitored in real time through color change, and the temperature visualization function is achieved; and the fabric also has good elasticity, moisture permeability, hydrophobicity and quick-drying property, and can meet the wearing experience of a user. The preparation method of the crystalline photosensitive material and the nanofiber fabric is simple, easy to operate, easy for large-scale production, wide in application scene and wide in market prospect.

Description

Technical Field

[0001] The present invention belongs to the technical fields of photosensitive materials and nanofiber fabrics, and relates to a crystalline photosensitive material and a method for preparing a wearable nanofiber fabric with temperature visualization function using the same. Background Art

[0002] In recent years, thermally managed fabrics have played an important role in improving energy utilization efficiency, maintaining human thermal comfort within the optimal temperature range, and adapting to dynamic environmental conditions, attracting extensive attention. Among numerous candidate fabrics, nanofiber fabrics stand out with their unique structural advantages, including high specific surface area, tunable porosity, and lightweight flexibility, better meeting the wearing experience needs of users. These materials have revolutionary application potential, from personal thermal regulation of wearable devices to large-scale energy-efficient buildings. Despite the breakthroughs made, achieving temperature visualization thermally managed in fabrics while maintaining a balance between photothermal performance and comfort remains a daunting challenge.

[0003] The latest progress in nanotechnology has made it possible to integrate photothermal agents into nanofibers. Traditional photothermal agents include noble metal nanoparticles (such as Au, Ag), polymeric materials (such as MXene, PDA, and PPy), and carbon-based nanostructures (such as graphene, carbon nanotubes). These materials exhibit excellent photothermal conversion performance by optimizing photon absorption and minimizing thermal radiation loss, making them the preferred materials for producing photothermal conversion fabrics. For example, in 2023, Yuan Jiayin et al. incorporated cesium tungsten bronze nanoparticles (Cs x(WO3) was embedded into nylon nanofibers as an additive to prepare an intelligent fabric for personal thermal management. Under different climate conditions, compared with a commercial sweatshirt that is six times thicker, the temperature resistance of this fabric increased by 2.5 - 10.5 °C, and the performance was further improved in a humid environment. (Jian Chang, Le Shi, Miao Zhang, Renyuan Li, YifengShi, Xiaowen Yu, Kanglei Pang, Liangti Qu, Peng Wang, and Jiayin Yuan. Tailor-Made White Photothermal Fabrics: A Bridge between Pragmatism andAesthetic. Advanced Materials 2023, 35, 2209215. DOI: 10.1002 / adma.202209215). Li Wenying et al. designed a new flexible wearable fabric that contains azobenzene-containing dendrimers, polydopamine, and cotton fabric. This fabric utilizes cis-trans isomerization and the photothermal effect under blue light irradiation to achieve the heating effect of the wearable fabric. (Xingtang Xu, Youmei Xing, Yunjian Yin, Weihua Fang, Bo Wu,Pengzhi Bei, Jie Feng, Haifeng Yu, Guojie Wang, Wen-Ying Li. Flexiblewearable fabrics for solar thermal energy storage and release in on-demandenvironments. Chemical Engineering Journal 2023, 466, 143175. DOI: 10.1016 / j.cej.2023.143175).

[0004] There are many fabrics currently used for personal thermal management. However, these fabrics still require external temperature sensors for thermal monitoring and lack a visual feedback mechanism in case of overheating, which greatly affects the comfort and safety of the wearer - this is a key bottleneck in the development of intelligent wearable systems. And in recent years, the developed thermal management fabrics with temperature visualization are constructed by simultaneously incorporating separate photothermal materials and color-changing materials into nanofibers. Therefore, developing an embedding agent with dual functions of photochromism and photothermal conversion is a necessary condition for promoting the development of the next generation of intelligent wearable nanofiber fabrics. Summary of the Invention

[0005] The object of the present invention is to overcome the deficiencies existing in the prior art and provide a crystalline photosensitive material and a method for preparing a wearable nanofiber fabric with temperature visualization function by using the same. First, a new crystalline photosensitive material was synthesized by self-assembly of 2,4,6-tris(4-pyridyl)-1,3,5-triazine (TPT) ligand and FeSO4·7H2O under solvothermal conditions. Then, the material was doped into a polyurethane (PU) fiber matrix by electrospinning to successfully construct a wearable nanofiber fabric. The fabric has excellent photothermal conversion performance and rapidly changes color under sunlight, and can indicate the temperature of the fabric by color change, so as to realize visual monitoring of temperature. And the wearable nanofiber fabric has good wearing comfort (elasticity, hydrophobicity, moisture permeability, quick drying). The present invention provides a method for synthesizing the target fabric by self-assembly technology and electrospinning means, which is easy to operate, simple and easy to scale up production.

[0006] In order to achieve the above object, the present invention provides a method for preparing a crystalline photosensitive material, and the specific steps are as follows:

[0007] (1) Mix 0.09 - 0.1 g of iron salt, 0.34 - 0.35 g of organic acid, 0.2 - 0.21 mL of N,N-dimethylacetamide (DMA) and 0.03 - 0.031 g of organic ligand evenly;

[0008] (2) Stir the mixture obtained in step (1) at room temperature for 10 - 30 minutes, then add phosphoric acid (H3PO4) to adjust the pH to about 3 - 4, put it into a high-pressure stainless steel reaction kettle for solvothermal reaction, keep the temperature at 120 °C for 6 - 7 days, take it out, cool it naturally to room temperature, wash the product with deionized water for many times, filter it with a suction filter and place the product in the dark to dry naturally to obtain yellow block crystals, that is, the crystalline photosensitive material.

[0009] The iron salt used in the present invention is ferrous sulfate heptahydrate; the organic acid is oxalic acid dihydrate; the organic ligand is 2,4,6-tris(4-pyridyl)-1,3,5-triazine (TPT); the volume of the stainless steel reaction kettle is 20 mL.

[0010] The present invention also provides the crystalline photosensitive material prepared by the above method. The molecular formula of this material is C 48 H 36 N 12 O 32 P2Fe2, which is yellow block crystals; and has dual functions of photochromism and photothermal conversion.

[0011] The crystalline photosensitive material described in the present invention was tested by single-crystal X-ray diffraction. The obtained data was analyzed by Olex2 software, and it was found that the material crystallizes in the P-1 space group of the triclinic system. The asymmetric unit contains a central Fe 3+ ion, two deprotonated oxalate groups, one HPO4 2- group, one free oxalic acid molecule, and one protonated H3-TPT. The molecular formula is C 48 H 36 N 12 O 32 P2Fe2.

[0012] The present invention also provides a method for preparing a wearable nanofiber fabric with temperature visualization function. The crystalline photosensitive material is added to the spinning solution, and a wearable nanofiber fabric with temperature visualization function is prepared by electrospinning process.

[0013] The spinning solution is an existing spinning solution that can be used to prepare wearable nanofiber fabrics. Preferably, the spinning solution is a polyurethane / N,N-dimethylacetamide (PU / DMA) solution with a PU concentration of 11-13 wt%. The polyurethane / N,N-dimethylacetamide solution is prepared by dissolving polyurethane in N,N-dimethylacetamide.

[0014] The mass ratio of the crystalline photosensitive material to the spinning solution in the present invention is (0.5-0.55):100.

[0015] The parameters of the electrospinning process described in the present invention are: the applied voltage is 16 kV, the spinning distance between the syringe needle tip and the collector is 14 cm, and the injection rate is 0.2 mL h -1 . The ambient temperature is 26 °C and the humidity is 40%.

[0016] The wearable nanofiber fabric described in the present invention has dual photo-responsive functions of photochromism and photothermal conversion. Under sunlight, it can produce a visible color change to the naked eye and generate a photothermal conversion effect.

[0017] The wearable nanofiber fabric described in the present invention can be used outdoors as a warming article, can effectively provide a warming effect under sunlight, and indicate the warming state through the color change of the fabric.

[0018] The innovation of the present invention lies in the development of a photosensitive material that simultaneously has photochromic and photothermal conversion functions. Using this crystalline photosensitive material as an embedding agent, it is incorporated into the nanofiber fabric through electrospinning. Without adding other photothermal components or color-changing components, the fabric can achieve photochromism and photothermal conversion. This crystalline photosensitive material undergoes a photodecomposition reaction under sunlight, showing a visible color change to produce stable free radical products, endowing the fabric with excellent photothermal conversion effects. Under sunlight irradiation, the temperature of the fabric rises from 22 °C to 42.5 °C within 600 seconds, and the color changes from light yellow to dark green. By judging the temperature based on the color depth, the thermal state can be visually monitored with the naked eye. Moreover, the present invention also evaluates the wearing comfort of the fabric and tests the heating effect of the fabric under outdoor conditions, achieving effective heat preservation under cold conditions, demonstrating the potential application of the fabric in wearable fabric devices.

[0019] Compared with the prior art fabrics that add both photothermal components and color-changing components, the present invention only needs to add one embedding agent (crystalline photosensitive material) to the fabric to achieve photochromism and photothermal conversion.

[0020] Compared with the prior art, the present invention provides a crystalline photosensitive material that simultaneously has dual functions of photochromism and photothermal conversion, and for the first time incorporates the crystalline photosensitive material into the photothermal fabric to achieve photochromism and photothermal conversion. The nanofiber fabric prepared by the present invention can exhibit photochromic phenomena and photothermal conversion effects under sunlight, and can monitor the thermal state in real time through color changes, realizing the function of temperature visualization. It can also show a significant heating effect under cold outdoor conditions. In addition, the nanofiber fabric has good elasticity, moisture permeability, hydrophobicity, and quick-drying properties, which can meet the wearing experience of users. The preparation method of the crystalline photosensitive material is simple and easy to operate, the preparation method of the nanofiber fabric is simple, efficient, and easy to scale up production. The fabric has good wearing comfort and a wide range of application scenarios, with broad market prospects. Description of the Drawings

[0021] Figure 1 Schematic diagram of the asymmetric unit structure principle of the crystalline photosensitive material involved in the present invention.

[0022] Figure 2 Picture of the color change of the crystalline photosensitive material involved in the present invention under xenon lamp (300 W) irradiation.

[0023] Figure 3 Flow chart of the crystalline photosensitive material involved in the present invention under 808 nm laser (0.7 W cm -2 ) irradiation.

[0024] Figure 4The heating curve of the crystalline photosensitive material before and after xenon lamp illumination involved in the present invention under the irradiation of an 808 nm laser (0.7 W cm -2 ).

[0025] Figure 5 The physical picture of the wearable nanofiber fabric involved in the present invention.

[0026] Figure 6 The powder X-ray diffraction patterns of the crystalline photosensitive material, pure PU fabric, and wearable nanofiber fabric involved in the present invention.

[0027] Figure 7 The scanning electron microscope picture of the wearable nanofiber fabric involved in the present invention.

[0028] Figure 8 The curve graph of the temperature change with time of the wearable nanofiber fabric involved in the present invention under irradiation with different sunlight intensities.

[0029] Figure 9 The thermal infrared pictures of the wearable nanofiber fabric and pure PU fabric involved in the present invention when pasted on the wrist and after removal, where A is the thermal infrared picture of the wearable nanofiber fabric and pure PU fabric pasted on the wrist, and B is the thermal infrared picture after removing the wearable nanofiber fabric.

[0030] Figure 10 The schematic diagram of the color change of the wearable nanofiber fabric and pure PU fabric involved in the present invention when pasted on the wrist under irradiation.

[0031] Figure 11 The optical physical pictures of the wearable nanofiber fabric and pure PU fabric involved in the present invention when reaching thermal stability on the human chest.

[0032] Figure 12 The thermal infrared pictures of the wearable nanofiber fabric and pure PU fabric involved in the present invention when reaching thermal stability on the human chest.

[0033] Figure 13 The schematic diagram of the temperature rise performance test device of the wearable nanofiber fabric, pure PU fabric, cotton fabric, and polyester involved in the present invention under outdoor conditions.

[0034] Figure 14 The curve graph of the temperature change with time of the wearable nanofiber fabric, pure PU fabric, cotton fabric, and polyester involved in the present invention under outdoor conditions.

[0035] Figure 15 The schematic diagram of the elastic performance test of the wearable nanofiber fabric involved in the present invention.

[0036] Figure 16Schematic diagram for testing the moisture permeability of the wearable nanofiber fabric involved in the present invention.

[0037] Figure 17 Schematic diagram for testing the hydrophobic angles of the wearable nanofiber fabric and the pure PU fabric involved in the present invention.

[0038] Figure 18 Temperature distribution and weight loss diagram of the pure PU fabric involved in the present invention after washing and irradiation with simulated sunlight.

[0039] Figure 19 Temperature distribution and weight loss diagram of the wearable nanofiber fabric involved in the present invention after washing and irradiation with simulated sunlight. Detailed implementation mode

[0040] The present invention will be further described below through examples in conjunction with the accompanying drawings.

[0041] Example 1:

[0042] This example relates to a preparation method of a crystalline photosensitive material, and the specific steps are as follows:

[0043] (1) Mix ferrous sulfate heptahydrate (0.09 g), oxalic acid dihydrate (0.35 g), N,N-dimethylacetamide (DMA) (0.2 mL) and 2,4,6-tris(4-pyridyl)-1,3,5-triazine (TPT) (0.03 g) evenly, and transfer them into a polytetrafluoroethylene inner liner;

[0044] (2) Stir the mixture obtained in step (1) at room temperature for 10 minutes, then add 0.1 mL of phosphoric acid (H3PO4) to adjust the pH to about 3-4, seal and place it in a 20 mL high-pressure stainless steel reaction kettle, keep the temperature at 120 °C for 6 days, take it out, naturally cool to room temperature, wash it with deionized water multiple times, filter it with a suction filter and place the product in the dark to dry naturally to obtain yellow block crystals, namely the crystalline photosensitive material (denoted as 1).

[0045] The structural formula of the 2,4,6-tris(4-pyridyl)-1,3,5-triazine is:

[0046]

[0047] This example conducts single crystal X-ray diffraction testing on the prepared crystalline photosensitive material, and imports the data into the Olex2 software for analysis. The data shows that the crystalline photosensitive material crystallizes in the P-1 space group of the triclinic system, and the asymmetric unit contains a central Fe 3+ ion, two deprotonated oxalate groups, and one HPO4 2-a group, a free oxalic acid molecule, and a protonated H3-TPT ( Figure 1 ). The molecular formula is C 48 H 36 N 12 O 32 P2Fe2. The molecular weight is 1466.53.

[0048] Example 2:

[0049] This example relates to a preparation method of a crystalline photosensitive material, and the specific steps are as follows:

[0050] (1) Mix 0.1 g of iron salt, 0.34 g of organic acid, 0.21 mL of N,N-dimethylacetamide (DMA), and 0.031 g of organic ligand evenly, and transfer them to a polytetrafluoroethylene inner liner;

[0051] (2) Stir the mixture obtained in step (1) at room temperature for 10 minutes, then add 0.1 mL of phosphoric acid (H3PO4) to adjust the pH to about 3-4, seal it and put it into a high-pressure stainless steel reaction kettle, keep it at a constant temperature of 120 °C for 7 days, take it out, naturally cool it to room temperature, wash it with deionized water multiple times, filter it with a suction filter, and place the product in the dark to dry naturally to obtain yellow block crystals, that is, the crystalline photosensitive material.

[0052] Example 3:

[0053] This example relates to the performance test of the crystalline photosensitive material prepared in Example 1, and the specific steps are as follows:

[0054] 1. Place the crystalline photosensitive material under the irradiation of a 300 W xenon lamp, observe the color change. The color change starts within 1 second. As the irradiation time is extended to 2 minutes, the color of the crystalline photosensitive material changes from yellow to dark green completely, as Figure 2 shown, which proves that the crystalline photosensitive material has photochromic behavior.

[0055] 2. Grind 0.2 g of the crystalline photosensitive material (named 1) into powder and place it on a quartz glass plate. Under the irradiation of an 808 nm near-infrared laser with a power of 0.7 W cm -2 , the temperature of the crystalline photosensitive material rises rapidly to 77 °C within 1 minute; place the crystalline photosensitive material (1A) after xenon lamp irradiation on a quartz glass plate. Under the irradiation of an 808 nm near-infrared laser with a power of 0.7 W cm -2 , the temperature rises rapidly to 147 °C ( Figure 4 ). After turning off the 808 nm laser, the temperatures of both drop to room temperature within 2 minutes, showing near-infrared photothermal conversion characteristics. In contrast, the temperature of the blank quartz plate does not change significantly.

[0056] Example 4:

[0057] This example relates to a preparation method of a wearable nanofiber fabric with temperature visualization function. The specific steps are as follows:

[0058] (1) Grind the crystalline photosensitive material (0.5 g) obtained in Example 1 into powder (particle size 20 - 100 nm) in an agate mortar, add it to 40 g of a PU / DMA solution with a PU concentration of 30 wt%, and add DMA for dilution. Continuously stir for 4 hours to ensure uniform dispersion of the crystals, obtaining a mixed electrospinning solution with a PU concentration of 12 wt%. Pour the mixed electrospinning solution into a syringe, then fix the syringe on an electrospinning machine, set the parameters (applied voltage 16 kV, distance between the syringe tip and the receiving device is 14 cm, injection flow rate is 0.2 mL h -1 ; environmental temperature is 26 °C, humidity is 40%), start spinning, and receive polyurethane fibers on the receiving device, thus obtaining a wearable nanofiber fabric with temperature visualization function (denoted as 1 / PU). The receiving device is a flat receiver.

[0059] The shape of the wearable nanofiber fabric prepared in this example is as Figure 5 shown, with a length of 30 cm and a width of 20 cm. X-ray diffraction test and scanning electron microscope test prove that the crystalline photosensitive material is successfully loaded on the fabric ( Figure 6 and Figure 7 ).

[0060] Example 5:

[0061] Under the condition of simulating sunlight with a xenon lamp (320 - 780 nm, 300 W), the photochromic and photothermal conversion properties of the wearable nanofiber fabric of Example 3 were tested. First, the heating curves of the wearable nanofiber fabric under different sunlight densities were tested ( Figure 8 ), within the intensity range of 20 - 80 mW cm -2 , the maximum temperatures that the wearable nanofiber fabric can rise from room temperature within 600 seconds are 27.6, 29.2, 31.7, 33.5, 35.3, 38.4 °C, 42.5 °C respectively, showing a linear growth trend. At the same time, the heating effects of the wearable nanofiber fabric and the pure PU fabric (without crystalline photosensitive material) on the wrist were tested respectively ( Figure 9 A). Within 600 seconds, 80 mW cm -2Under intense irradiation, the surface temperature of the wearable nanofiber fabric was recorded by an infrared imager to rise sharply from room temperature to 44.4 °C, while the surface temperature of the pure PU fabric did not change significantly, which confirmed the excellent photothermal conversion performance of the wearable nanofiber fabric. After removing the wearable nanofiber fabric, the residual temperature on the wrist slowly dissipated within 30 seconds ( Figure 9 B), showing superior thermal energy conversion efficiency. During the entire illumination process, the color of the wearable nanofiber fabric exhibited a temperature-dependent color change from light yellow to emerald green ( Figure 10 ). This inherent photochromic function enables real-time visual temperature monitoring through color intensity changes, effectively preventing the risk of skin overheating while maintaining a suitable thermal range.

[0062] Example 6:

[0063] This example involves a test of the photothermal conversion performance of the wearable nanofiber fabric prepared in Example 3 under cold outdoor conditions, and compares the heating performance of the wearable nanofiber fabric with that of pure PU fabric and traditional fabrics (cotton fabric and polyester). Under outdoor conditions, samples of the wearable nanofiber fabric and pure PU fabric were cut into appropriate sizes and attached to the chest position of the human body ( Figure 11 ). As the sunlight irradiation time increased, the infrared thermal imaging images showed that the surface temperature of the wearable nanofiber fabric after reaching thermal equilibrium was significantly higher than that of the pure PU fabric ( Figure 12 ), confirming its superior radiative heating ability.

[0064] Under cold outdoor conditions, the heating effects of the wearable nanofiber fabric, pure PU fabric, cotton fabric, and polyester were compared using Figure 13 a device. Specifically: Four sample fabrics were respectively adhered to the sample area, and thermocouples were respectively connected to the samples to display the surface temperature of the samples in real time. A densitometer was used to measure the change in sunlight intensity during the day, and the power supply was able to maintain the normal operation of the thermocouples, densitometer, and computer. The above device was placed in the outdoor environment to test the sunlight intensity, ambient air temperature, and the heating effects of the four fabrics during the period from 11:30 to 16:30. The densitometer recorded the ambient temperature range from 1.9 °C to 16 °C and the solar intensity from 32 - 48.6 mW cm -2 . At the same time, from Figure 14It can be seen that the surface temperature of the wearable nanofiber fabric is 7.7 - 36.6 °C, which is 5.2 - 11.9 °C higher than that of the pure PU fabric (surface temperature: 2.5 - 24.7 °C), 5.5 - 11.4 °C higher than that of the cotton fabric (surface temperature: 2.2 - 25.2 °C), and 5.2 - 12.1 °C higher than that of the polyester (surface temperature: 2.5 - 24.5 °C). This proves that the wearable nanofiber fabric exhibits excellent photothermal conversion performance under outdoor conditions, and this performance is significantly higher than that of traditional fabrics. This example demonstrates the potential of wearable nanofiber fabrics for practical outdoor applications in cold climate conditions.

[0065] Example 7:

[0066] This example relates to the wearing comfort test of the wearable nanofiber fabric prepared in Example 2.

[0067] Using Figure 15 the device shown in the figure, the elasticity of the wearable nanofiber fabric was tested. The fabric can withstand the stretching of a 200 - gram heavy object without breaking. And when holding both ends of the fabric with both hands, whether it is stretched horizontally or curled, the wearable nanofiber fabric can still restore its original shape, indicating excellent elasticity.

[0068] Using Figure 16 a simple device, the moisture permeability of the wearable nanofiber fabric was tested. Specifically, an appropriate amount of water was added to a beaker and placed on a heating platform. The wearable nanofiber fabric was fixed at the mouth of the beaker, and at the same time, some blue silica gel particles were placed on the wearable nanofiber fabric. By continuously heating the beaker, the silica gel particles on the wearable nanofiber fabric showed a rapid color change (blue → pink) within 10 minutes when exposed to hot water vapor, confirming the moisture permeability of the wearable nanofiber fabric. In addition, a hydrophobic angle tester was used to test the water contact angles of the pure PU fabric and the wearable nanofiber fabric to test the hydrophobic properties. Figure 17 It can be obtained that the water contact angle of the wearable nanofiber fabric (136.4°) is significantly larger than that of the pure PU fabric (119.9°). This is due to the roughening of the fiber surface caused by the embedding of the crystalline photosensitive material, confirming that the wearable nanofiber fabric has good hydrophobicity.

[0069] The quick - drying performance of the wearable nanofiber fabric and the pure PU fabric in the wet state under simulated sunlight was further evaluated. The same - sized wearable nanofiber fabric and pure PU fabric were immersed in water until completely wet, then taken out and placed under simulated sunlight (light density is 80 mW cm -2 )), an infrared imager was used to record the temperature change, and an electronic balance was used to record the weight loss every once in a while. The results are as Figure 18 - 19 shown. From Figure 18It can be seen that the pure PU fabric stops losing weight after 240 seconds of irradiation, and the moisture is completely evaporated. From Figure 19 It can be seen that the wearable nanofiber fabric stops losing weight after 100 seconds of irradiation and reaches the dry state. The water evaporation rate of the wearable nanofiber fabric is 4.1 times faster than that of the pure PU fabric, which confirms the excellent quick-drying performance of the wearable nanofiber fabric. This example proves that the wearable nanofiber fabric has excellent elasticity, moisture permeability, hydrophobicity and quick-drying property, and can be used as an excellent wearable fabric.

Claims

1. A method for preparing a crystalline photosensitive material, characterized in that, The specific steps are as follows: Mix ferric salt, organic acid, 2,4,6-tris(4-pyridyl)-1,3,5-triazine and N,N-dimethylacetamide, and stir evenly; adjust the pH to 3-4 with phosphoric acid; then put it into a high-pressure stainless steel autoclave for solvothermal reaction; wash and dry to obtain a crystalline photosensitive material.

2. The preparation method of a crystalline photosensitive material according to claim 1, characterized in that, The ferric salt is ferrous sulfate heptahydrate; the organic acid is oxalic acid dihydrate.

3. The preparation method of a crystalline photosensitive material according to claim 1, characterized in that, The solvothermal reaction temperature is 120 °C and the time is 6-7 days.

4. The preparation method of a crystalline photosensitive material according to claim 2, characterized in that, The dosage ratio of the ferrous sulfate heptahydrate, oxalic acid dihydrate, 2,4,6-tris(4-pyridyl)-1,3,5-triazine and N,N-dimethylacetamide is (0.09-0.1 g):(0.34-0.35 g):(0.03-0.031 g):(0.2-0.21 mL).

5. The crystalline photosensitive material prepared by the preparation method according to any one of claims 1-3, characterized in that, The molecular formula of this material is C 48 H 36 N 12 O 32 P2Fe2, which is a yellow massive crystal; it has dual functions of photochromism and photothermal conversion.

6. A preparation method of a wearable nanofiber fabric with a temperature visualization function, characterized in that, Add the crystalline photosensitive material described in Claim 5 to the spinning solution, and use the electrospinning process to prepare a wearable nanofiber fabric with temperature visualization function.

7. The preparation method of the wearable nanofiber fabric with temperature visualization function according to claim 6, characterized in that, The spinning solution is a polyurethane / DMA solution; the mass ratio of the crystalline photosensitive material to the spinning solution is (0.5-0.55):

100.

8. The preparation method of a wearable nanofiber fabric with temperature visualization function according to claim 1, characterized in that, The electrospinning process parameters are as follows: the applied voltage is 16 kV, the spinning distance between the syringe tip and the collector is 14 cm, and the injection rate is .

9. The wearable nanofiber fabric with temperature visualization function prepared by the preparation method according to any one of claims 6-8, characterized in that, It has dual photoresponse functions of photochromism and photothermal conversion, can produce a visible color change under sunlight, and produces a photothermal conversion effect.

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