Electrostatic spinning colorimetric humidity sensing film and construction method thereof

Abstract

The invention discloses an electrostatic spinning colorimetric humidity sensing film and a construction method thereof, and the colorimetric humidity sensing film is prepared by taking poly (4-styrenesulfonic acid) and polyvinyl acetate as matrixes, coumarin 6 as a luminescent dye and absolute ethyl alcohol as a solvent to obtain a spinning solution and then performing electrostatic spinning. The colorimetric humidity sensing film is used as a colorimetric humidity sensor material, and has the advantages of reversible reaction, portability, flexibility, wearable performance, high sensitivity, high reaction speed, good linear fitting degree and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of electrostatic spinning colorimetric humidity sensing film and its construction method, belong to colorimetric humidity sensor technical field. BACKGROUND

[0002] As a new humidity monitoring technology, colorimetric humidity sensors have a wide range of applications in environmental monitoring, smart homes, agriculture, medicine and food due to their low cost, ease of use and high sensitivity. The basic principle of colorimetric humidity sensors is usually based on the adsorption or release of water by the material. The color change caused by humidity change is used to detect the moisture content in the air. They usually use materials that can react to humidity changes, which change color under different humidity conditions.

[0003] In recent years, the research of colorimetric humidity sensors has continued to progress, focusing on improving the sensitivity, stability, response speed and practical application performance of the sensors. Existing colorimetric humidity sensors do not have obvious color change under low humidity conditions, cannot meet the needs of visual comparison, have poor sensitivity, and the color changes when reaching a certain humidity gradient value (usually 50%-60%) are not linear. This color change may be due to the material's own characteristics or insufficient and uneven humidity absorption, resulting in a large error when comparing colors by the human eye or artificial intelligence algorithms at this humidity gradient value. SUMMARY

[0004] The present application provides a high-performance electrospun colorimetric humidity sensing film and its construction method. The colorimetric humidity sensing film constructed by the present application still has high sensitivity in low humidity environments, and the color change is stable as humidity increases, without sudden color changes, and has good linearity.

[0005] To solve the above technical problems, the present application provides the following technical solutions: An electrospun colorimetric humidity sensing film is prepared by mixing poly(4-styrene sulfonic acid) and polyvinyl acetate as a matrix, coumarin 6 as a luminescent dye, and anhydrous ethanol as a solvent, and then electrospinning the obtained spinning solution.

[0006] A construction method of an electrospun colorimetric humidity sensing film, comprising the following steps: (1) Mix the poly(4-styrene sulfonic acid) aqueous solution with coumarin 6 to obtain a mixed solution; (2) Add a solvent to the mixed solution, mix uniformly, and then filter to obtain a filtered solution; (3) Mix the filtered solution with polyvinyl acetate to obtain a spinning solution; (4) electrospinning the spinning solution to obtain the colorimetric humidity sensing film.

[0007] Preferably, the mass ratio of the aqueous solution of poly(4-styrene sulfonic acid) to coumarin 6 in step (1) is (35-45):1.

[0008] Preferably, the solvent in step (2) is anhydrous ethanol.

[0009] Preferably, the volume ratio of the mixed solution to anhydrous ethanol in step (2) is 1:(4-6).

[0010] Preferably, after mixing the mixed solution with the solvent in step (2), the mixed solution is filtered through a filter with a pore size of 0.18-0.32 microns to obtain a filtered solution.

[0011] Preferably, the mass ratio of polyvinyl acetate to the filtered solution in step (3) is (1-3):20.

[0012] Preferably, the filtered solution and polyvinyl acetate are mixed in step (3) at 50 o C-60 o The mixture is stirred in a C-water bath for 1.5-3 hours.

[0013] Preferably, the negative voltage for electrospinning in step (4) is 2KV-3KV, the flow rate is 0.12mm / min, and the positive voltage is 15KV-17KV.

[0014] Preferably, the mixed solution and the solvent in step (2) are mixed at 45 o C-55 o C ultrasonic treatment for 1.5-2.5 hours.

[0015] Compared with the prior art, the present application has the following advantages: 1. The colorimetric humidity sensing film prepared by the electrospinning process of the present application uses two hydrophilic polymers, poly(4-styrene sulfonic acid) (PSSA) and polyvinyl acetate (PVAc), as the matrix, and coumarin 6 (C6) as the luminescent dye, and has the advantages of reversible reaction, portable and flexible wearable, high sensitivity, high reaction speed, good linear fitting degree, etc.

[0016] 2、The two polymers PSSA and PVAc in the application have high molecular weight, that is, the viscosity of the electrospinning solution is improved, the hydration performance is guaranteed, and the flexibility and ductility of the film are enhanced; PSSA and PVAc jointly play a role in absorbing water vapor, the hydrophilicity of the two makes the colorimetric humidity sensing film effectively absorb moisture, and the hygroscopicity is significantly improved; and the addition of PVAc not only enhances the sensitivity of the film to water vapor under low humidity, but also increases the viscosity of the spinning solution, so that the spinning solution can be made into a spinning film by the electrospinning method.

[0017] 3、The colorimetric humidity sensing film prepared by electrospinning in the application has a "net-like porous nanofiber" structure, so that the prepared sensing film is more sensitive and uniform to the response of water molecules in the atmosphere, and presents a more linear response to the change of water molecules in the atmosphere.

[0018] 4、The addition of PVAc and the porous structure inside the colorimetric humidity sensing film in the application can enhance the sensitivity to water molecules in the atmosphere, and the addition of PVAc can significantly improve the humidity response of the colorimetric humidity sensing film under low humidity or high humidity, and improve the detection upper and lower limits and the linearity.

[0019] 5、The color change is quantified by the color difference formula, which is related to the change of humidity in the atmosphere, has a more accurate corresponding relationship, and makes the test result more accurate and precise.

[0020] 6、The electrospinning can manufacture ultrafine fibers with a diameter of several nanometers to several microns, usually in nanometer scale, due to its ultrafine fibers, high specific surface area and porous structure, the response to water molecules in the atmosphere is extremely sensitive, and the color change reaction is more uniform, so that it has better linear fitting degree. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 a) is the SEM graph of the colorimetric humidity sensing film in Example 1; Figure 1 b) is the SEM graph of the colorimetric humidity sensing film in Comparative Example 4; Figure 2 a) is the RGB humidity change graph of the humidity color-changing spinning solution using glass sheet spin coating method in Example 1; Figure 2 b) is the RGB humidity change graph of the uniform solution using glass sheet spin coating method in Example 1; Figure 2 c) is the RGB humidity change graph of the colorimetric humidity sensing film in Example 1; Figure 2d) Color difference ΔE for glass slide spin coating of humidity color changing spinning solution in Example 1; Figure 2 e) Color difference ΔE for glass slide spin coating of uniform solution in Example 1; Figure 2 f) Color difference ΔE for colorimetric humidity sensing film in Example 1; Figure 3 a) RGB change graph for colorimetric humidity sensing film with positive voltage of 7KV in electrospinning; Figure 3 b) RGB change graph for colorimetric humidity sensing film with positive voltage of 11.5KV in electrospinning; Figure 3 c) RGB change graph for colorimetric humidity sensing film with positive voltage of 16KV in electrospinning; Figure 3 d) RGB change graph for colorimetric humidity sensing film with positive voltage of 20KV in electrospinning; Figure 4 CIE2000 color difference ΔE change curve for colorimetric humidity sensing film of Comparative Example 1, Comparative Example 2, Example 1; Figure 5 a) RGB change graph with humidity for PVAc and filtered uniform solution with mass ratio of 1:20; Figure 5 b) RGB change graph with humidity for PVAc and filtered uniform solution with mass ratio of 3:40; Figure 5 c) RGB change graph with humidity for PVAc and filtered uniform solution with mass ratio of 3:20; Figure 5 d) Color difference ΔE for PVAc and filtered uniform solution with mass ratio of 1:20; Figure 5 e) Color difference ΔE for PVAc and filtered uniform solution with mass ratio of 3:40; Figure 5 f) Color difference ΔE for PVAc and filtered uniform solution with mass ratio of 3:20; Figure 6 a) Film surface for PVAc and filtered uniform solution with mass ratio of 1:20; Figure 6 b) Film surface for PVAc and filtered uniform solution with mass ratio of 3:40; Figure 6 c) Film surface for PVAc and filtered uniform solution with mass ratio of 1:10; Figure 6 d) is the surface of the film when the mass ratio of PVAc to the filtered homogeneous solution is 3:20; Figure 7 a) is the comparison of the response time change of the spin coating method and the spinning film when the atmospheric humidity (20%) is transferred to 60% humidity; Figure 7 b) is the comparison of the response time when the same ΔE changes; Figure 8 Figure is the film surface change diagram of the colorimetric humidity sensing film prepared in Example 2 under the condition that the humidity environment changes from 15% to 60% and then to 15%; Figure 9 Figure is the color difference ΔE of the colorimetric humidity sensing film prepared in Example 2 after the humidity changes from 15% to 60% repeatedly. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the accompanying drawings.

[0023] The present application relates to a static spinning colorimetric humidity sensing film, which uses poly(4-styrene sulfonic acid) (PSSA) and polyvinyl acetate (PVAc) as the base of two hydrophilic polymer polyelectrolytes, adds coumarin 6 (C6) as a luminescent dye, and uses anhydrous ethanol as a solvent to prepare a spinning solution. The colorimetric humidity sensing film is obtained by electrospinning the spinning solution.

[0024] When constructing the colorimetric humidity sensing film, some aromatic hydrocarbons, ketones, alcohols, and esters can be used as solvents, but the dissolution effect and spinning effect are not as good as anhydrous ethanol. Anhydrous ethanol is used as a solvent to dissolve PSSA and C6, which can effectively dissolve PSSA and C6, obtain a stable and not easy to precipitate dye-polyelectrolyte complex, and dissolve polyvinyl acetate in alcohol solvents. Finally, ethanol has a low boiling point and is easy to evaporate, which can quickly evaporate from the solution during electrospinning, so that the polymer quickly forms fibers without causing excessive expansion or instability of the solution.

[0025] Example 1 The construction method of the colorimetric humidity sensing film includes the following steps: (1) A proper amount of poly(4-styrene sulfonic acid) (PSSA) aqueous solution is added to a glass beaker, and coumarin 6 (C6) is mixed at a mass ratio of 40:1 to obtain a mixed solution A; (2) Anhydrous ethanol is added to the mixed solution A to obtain a mixed solution B, and the volume ratio of the mixed solution A to anhydrous ethanol is 1:5; (3) The mixed solution B is ultrasonically treated for two hours under the condition of 50 o C to obtain a homogeneous solution. (4) Filter the homogeneous solution from step (3) using a PTFE syringe filter with a pore size of 0.22 μm; (5) Mix polyvinyl acetate (PVAc) with the filtered homogeneous solution at a mass ratio of 1:20, and heat at 55°C. o The solution for spinning with humidity-sensitive color was obtained by stirring in a water bath for two hours under condition C. (6) The humidity-changing spinning solution was electrospun. The electrospinning parameters were: negative voltage 2.5KV, flow rate 0.12mm / min, and positive voltage 16KV. A colorimetric humidity sensing film was obtained.

[0026] SEM analysis was performed on the colorimetric humidity sensing film prepared in Example 1, such as... Figure 1 a) and Figure 1 As shown in b), SEM characterization analysis reveals a filamentous porous structure that greatly increases the contact area with water vapor in the atmosphere and enhances the sensitivity to water molecules. Moreover, this structure has excellent flexibility and can be used in a variety of flexible application scenarios.

[0027] A color change comparison experiment was conducted using the glass slide spin-coating method. The homogeneous solution from step (3) of Example 1 and the humidity-sensitive color-changing spinning solution from step (5) were spin-coated onto glass slides respectively, and their various color change data were tested, such as... Figure 2 b) and Figure 2 As shown in e), the homogeneous solution without added PVAc showed no significant color change under both low and high humidity conditions, exhibiting a high lower detection limit and a low upper detection limit. Furthermore, the overall linearity of the color change data was poor; within the 60%-70% humidity range, the color change was drastic, easily leading to significant errors. Figure 2 a) and Figure 2 As shown in d), the humidity-sensitive spinning solution after adding PVAc exhibits a more significant color change compared to the homogeneous solution, and its humidity response under low humidity conditions is significantly improved. Figure 2 d) and Figure 2 e) When the humidity is between 30% and 50%, such as Figure 2 As shown in d), the humidity-sensitive spinning solution with added PVAc exhibits more pronounced color change and humidity response. However, within the 45%-65% humidity range, drastic color changes still occur, and no significant color change is observed under high humidity conditions (greater than 65%). The colorimetric humidity sensing film prepared by electrospinning in this embodiment was subjected to a color change test, as shown... Figure 2 c) and Figure 2f) The colorimetric humidity sensing film showed a much better linearity than the color change coating prepared by spin-coating on a glass slide. Therefore, it can be concluded that the addition of PVAc and the porous structure inside the colorimetric humidity sensing film can enhance its sensitivity to the water molecules in the atmosphere.

[0028] Example 2 The method for constructing the colorimetric humidity sensing film includes the following steps: (1) A proper amount of poly(4-styrene sulfonic acid) (PSSA) aqueous solution was added to a glass beaker, and then coumarin 6 (C6) was added with a mass ratio of 38:1 to obtain a mixed solution A; (2) Anhydrous ethanol was added to the mixed solution A to obtain a mixed solution B, and the volume ratio of the mixed solution A to the anhydrous ethanol was 1:4; (3) The mixed solution B was ultrasonically treated for 1.5 hours under the condition of 48 o C until the C6 was completely dissolved to obtain a uniform solution; (4) The uniform solution in step (3) was filtered by using a PTFE syringe filter with a pore size of 0.18 μm; (5) Polyvinyl acetate (PVAc) was mixed with the filtered uniform solution with a mass ratio of 3:40, and was stirred in a water bath kettle under the condition of 50 o C for 1.5 hours to obtain a humidity color change spinning solution; (6) The humidity color change spinning solution was electrospun, and the electrospinning parameters were as follows: a negative voltage of 2 KV, a flow rate of 0.12 mm / min, and a positive voltage of 17 KV. A colorimetric humidity sensing film was obtained.

[0029] Example 3 The method for constructing the colorimetric humidity sensing film includes the following steps: (1) A proper amount of poly(4-styrene sulfonic acid) (PSSA) aqueous solution was added to a glass beaker, and then coumarin 6 (C6) was added with a mass ratio of 38:1 to obtain a mixed solution A; (2) Anhydrous ethanol was added to the mixed solution A to obtain a mixed solution B, and the volume ratio of the mixed solution A to the anhydrous ethanol was 1:4; (3) The mixed solution B was ultrasonically treated for 1.5 hours under the condition of 48 o C until the C6 was completely dissolved to obtain a uniform solution; (4) The uniform solution in step (3) was filtered by using a PTFE syringe filter with a pore size of 0.18 μm; (5) Polyvinyl acetate (PVAc) was mixed with the filtered uniform solution with a mass ratio of 3:40, and was stirred in a water bath kettle under the condition of 50 oThe humidity discoloring spinning solution was obtained by stirring in a water bath for 2.5 hours under condition C; (6) The humidity discoloring spinning solution was electrospun, and the electrospinning parameters were as follows: negative voltage 3 KV, flow rate 0.12 mm / min, and positive voltage 15 KV. A colorimetric humidity sensing film was obtained.

[0030] Example 4 The method for constructing the colorimetric humidity sensing film comprises the following steps: (1) A proper amount of poly(4-styrene sulfonic acid) (PSSA) aqueous solution was added into a glass beaker, and coumarin 6 (C6) was added at a mass ratio of 42:1 to obtain a mixed solution A; (2) Anhydrous ethanol was added into the mixed solution A to obtain a mixed solution B, and the volume ratio of the mixed solution A to the anhydrous ethanol was 1:5.5; (3) The mixed solution B was ultrasonically treated for 2.5 hours under condition C until the C6 was completely dissolved to obtain a uniform solution; o C, and the humidity discoloring spinning solution was obtained by stirring in a water bath for 2.5 hours under condition C; (4) The uniform solution in step (3) was filtered by using a PTFE syringe filter with a pore size of 0.32 μm; (5) Polyvinyl acetate (PVAc) was mixed with the filtered uniform solution at a mass ratio of 5:40, and the mixture was heated to 60 o C, and the humidity discoloring spinning solution was obtained by stirring in a water bath for 2.5 hours under condition C; The humidity discoloring spinning solution was electrospun, and the electrospinning parameters were as follows: negative voltage 3 KV, flow rate 0.12 mm / min, and positive voltage 15 KV. A colorimetric humidity sensing film was obtained.

[0031] It was found through experiments that the negative voltage of electrospinning was preferably between 2 KV and 3 KV, too low negative voltage (less than 2 KV) would result in no uniform spinning film, and too high negative voltage (more than 3 KV) would result in the spun filament being broken; the flow rate of electrospinning was preferably about 0.12 mm / min, too low flow rate would result in uneven spinning, and too high flow rate would result in spinning phenomenon; through adjustment of the positive voltage, it was found that when the positive voltage was lower than 7 KV, the electrospinning was very slow, the spinning was uneven, the fiber was thicker, and the discoloring effect was poor; when the positive voltage was higher than 20 KV, it was almost impossible to form a fiber, and the nanofiber was broken; when the positive voltage was between 7 KV and 20 KV, a relatively uniform film could be formed, but if the positive voltage was out of this range, a film could not be formed, and subsequent test experiments could not be carried out. The experimental results showed that the preferable range of the positive voltage was 15 KV to 17 KV, and the spinning film effect was best when the positive voltage was 16 KV.

[0032] Comparative Example 1 Referring to Example 1, the difference is that the positive voltage of electrospinning is 7KV.

[0033] Comparative Example 2 Referring to Example 1, the difference is that the positive voltage of electrospinning is 11.5KV.

[0034] Comparative Example 3 Referring to Example 1, the difference is that the positive voltage of electrospinning is 20KV.

[0035] Comparative Example 4 Referring to Example 1, the difference is that the mass ratio of PVAc to the filtered uniform solution is 3:40.

[0036] Comparative Example 5 Referring to Example 1, the difference is that the mass ratio of PVAc to the filtered uniform solution is 1:10.

[0037] Comparative Example 6 Referring to Example 1, the difference is that the mass ratio of PVAc to the filtered uniform solution is 3:20.

[0038] Performance test of comparative color humidity sensing film Place the color humidity sensing film sample on the filter paper, then place it in the transparent acrylic constant temperature and humidity box with adjustable temperature and humidity, wrap a circle of LED light belt around the transparent acrylic constant temperature and humidity box to reduce the error caused by light and shadow when analyzing RGB color, place the camera or mobile phone directly above the color humidity sensing film sample, and aim at the color humidity sensing film sample for shooting, adjust the humidity in the box, take pictures and record the color change at each humidity gradient.

[0039] Data collection is performed on each sample of Example 1 and Comparative Examples 1-3. The color humidity sensor shows different RGB value changes under different positive voltage values of electrospinning. As shown in Figure 3 a)、 Figure 3 b), when the voltage is low (7KV, 11.5KV), the spinning is not uniform due to the low voltage, the fiber is thick, and the air moisture cannot be fully absorbed, the R value in RGB shows different degrees of nonlinear transformation, and the R value appears mutation in some humidity range. As shown in Figure 3 d), when the positive voltage is high (20KV), the receiving end of electrospinning is difficult to receive a flat fiber film, and serious breaking phenomenon occurs, and the finally measured data is also extremely unstable. As shown in Figure 3c) as shown, when the positive voltage is in the range of 15KV-17KV (16KV), the R value changes smoothly with the change of humidity, and shows a monotonous upward trend, which is conducive to accurate colorimetry. Color difference analysis was carried out using CIE2000 color difference formula, as shown in Figure 4 As shown in the figure, when the electrospinning positive voltage is 16KV, the peak value of color difference is the highest, which indicates that the degree of color change is greater, and the change of air humidity can be better reflected from the change of color.

[0040] Data collection was carried out on each sample of example 1 and comparative examples 4-6. Under the condition of unchanged electrospinning parameters, the mass ratio of PVAc was different, and the color change data of each sample was tested. Color difference analysis was carried out using CIE2000 color difference formula, as shown in Figure 5 a), Figure 5 b), Figure 5 d) and Figure 5 e) as shown, when the mass ratio of PVAc is low (the mass ratio of PVAc to the filtered uniform solution is 1:20 or 3:40), the color change curve is more stable, and there is no mutation phenomenon, and the error is relatively small. And under high humidity, the humidity value can still be reflected by color change, and the peak value of measurable humidity value is higher. As shown in Figure 5 c) and Figure 5 f) as shown, when the mass ratio of PVAc is high (the mass ratio of PVAc to the filtered uniform solution is 3:20), the color change curve fluctuates, and the color change is not accurate under high humidity.

[0041] As shown in Figure 6 a)- Figure 6 d) can be seen, the smaller the mass ratio of PVAc, the more uniform the surface of the colorimetric humidity sensing film, and the higher the mass ratio of PVAc, the more uneven the surface of the colorimetric humidity sensing film, showing a fluffy structure like cotton.

[0042] By adjusting the mass ratio of PVAc, it is found that when the mass ratio of PVAc to the filtered uniform solution is less than 1:20, the humidity color-changing spinning solution is not viscous enough to be electrospun, and jetting phenomenon occurs during the spinning process, which seriously affects the formation of the fiber film. When the mass ratio of PVAc to the filtered uniform solution is higher than 3:20, the humidity color-changing spinning solution is spun, and the spinneret is blocked during the spinning process, and the surface of the spun fiber film is very uneven, showing a cotton-like shape, which cannot form a film, seriously affecting the subsequent data test. The addition of PVAc not only enhances the water absorption of the colorimetric humidity sensing film, but also increases the viscosity of the spinning solution, facilitating electrospinning. It is found through experiments that when the mass ratio of PVAc to the filtered uniform solution is between (1-3):20, a relatively uniform film can be formed by electrospinning. When the mass ratio of PVAc to the filtered uniform solution is 1:20 and 3:40, the surface of the spun film is smoother and the film-forming property is better.

[0043] Through comparison of multiple examples, it is found that when the mass ratio of PVAc to the filtered uniform solution is 1:20 and 3:40, and the positive voltage of electrospinning is 16KV, the colorimetric humidity sensing film has the best color-changing effect.

[0044] The colorimetric humidity sensing film prepared by the glass sheet spin coating method of the uniform solution of step (3) in Example 1 and the electrospinning method of the humidity color-changing spinning solution of step (5) in Example 1 are compared, their color-changing data are tested, and the color difference is analyzed by using CIE2000 color difference formula, as shown in Figure 7 a), the change slope of ΔE of the two methods under the same humidity change is almost the same; as shown in Figure 7 b), in the same ΔE change interval (ΔΔE=6), the response speed of the spun film to humidity is faster, which is about 32.1% faster than that of the spin coating method. From Figure 7 a) and Figure 7 b), it can be seen that the combination of PSSA and C6 is very sensitive to the response of water molecules in the atmosphere, and has a fast response speed. With the addition of PVAc, the colorimetric humidity sensing film prepared by the electrospinning method not only further enhances the water absorption of the colorimetric humidity sensing film, but also has a more sensitive response to water molecules in the atmosphere, and further improves the response speed to humidity on the basis of retaining its fast response speed. Figure 1

[0045] ​Further, the reversible reaction test was performed using the colorimetric humidity sensing film prepared in Example 2 as a sample. The colorimetric humidity sensing film was first changed from a humidity environment of 15% to a humidity environment of 60%, and then changed again to a humidity environment of 15%. As shown in FIG. 6, the color of the colorimetric humidity sensing film was restored to the initial color after the humidity cycle. The change in ΔE after repeating the humidity change from 15% to 60% several times is shown in FIG. 7. Figure 8 As shown in FIG. 6, the color of the colorimetric humidity sensing film was restored to the initial color after the humidity cycle. The change in ΔE after repeating the humidity change from 15% to 60% several times is shown in FIG. 7. Figure 9 As shown in FIG. 7, the color response of the colorimetric humidity sensing film was good in repeatability, and the degree of color change of the colorimetric humidity sensing film was relatively stable. The base state after the color change at low humidity was also relatively consistent, and the colorimetric humidity sensing film had stability and reliability under the humidity cycle conditions.

Claims

1. A static electrospinning colorimetric humidity sensing film, characterized in that: The colorimetric humidity sensing film is prepared by electrospinning after mixing poly (4-styrene sulfonic acid) and polyvinyl acetate as a matrix, coumarin 6 as a luminescent dye, and anhydrous ethanol as a solvent to obtain a spinning solution. 2.A method for constructing a static electrospinning colorimetric humidity sensing film, characterized in that: It comprises the following steps: (1) Mix the poly (4-styrene sulfonic acid) aqueous solution with coumarin 6 to obtain a mixed solution; (2) Add a solvent to the mixed solution, mix uniformly, and then filter to obtain a filtered solution; (3) Mix the filtered solution with polyvinyl acetate to obtain a spinning solution; (4) Electrospinning the spinning solution to obtain a colorimetric humidity sensing film.

3. The method of claim 2, wherein the electrospun colorimetric humidity sensing thin film is constructed by: The mass ratio of poly (4-styrene sulfonic acid) aqueous solution to coumarin 6 in step (1) is (35-45):

1.

4. The method of claim 2, wherein the electrospun colorimetric humidity sensing thin film is constructed by: The solvent in step (2) is anhydrous ethanol.

5. The method of claim 4, wherein the electrospun colorimetric humidity sensing thin film is constructed by: The volume ratio of the mixed solution to anhydrous ethanol in step (2) is 1:(4-6).

6. The method of claim 2, wherein the electrospun colorimetric humidity sensing thin film is constructed by: After mixing the mixed solution with the solvent in step (2), the mixed solution is filtered through a filter with a pore size of 0.18-0.32 μm to obtain a filtered solution.

7. The method of claim 2, wherein the electrospun colorimetric humidity sensing thin film is constructed by: The mass ratio of polyvinyl acetate to the filtered solution in step (3) is (1-3):

20.

8. The method of claim 2 or 7, wherein the electrospun colorimetric humidity sensing thin film is constructed by: The solution filtered in step (3) is mixed with polyvinyl acetate at 50 o C-60 o The mixture is stirred in a C-water bath for 1.5-3 hours.

9. The method of constructing an electrospun colorimetric humidity sensing film according to any one of claims 2 to 7, wherein: The negative voltage for electrospinning in step (4) is 2KV-3KV, the flow rate is 0.12mm / min, and the positive voltage is 15KV-17KV.

10. The method of constructing an electrospun colorimetric humidity sensing film according to any one of claims 2 to 7, wherein: The mixing solution in step (2) is mixed with the solvent at 45 o C-55 o Cultrasonic mixing is performed for 1.5-2.5 hours.

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