Pressure-sensitive polymer film as well as preparation method and application thereof

Abstract

The invention discloses a preparation method of a pressure-sensitive polymer film, which comprises the following steps: adding cobalt hexacyanocobaltate and propylene oxide into a high-pressure kettle, sealing the high-pressure kettle, filling carbonyl sulfide, preheating, carrying out copolymerization at 80-85 DEG C, cooling after the reaction is finished, and releasing carbonyl sulfide to obtain a PPMNTC (Polypropylene Monomer Negative Temperature Coefficient) copolymer; the preparation method comprises the following steps: dissolving a PPMNTC copolymer in N, N-dimethylformamide to obtain a spin-coating liquid, spin-coating the spin-coating liquid on a substrate, annealing and curing, and carrying out deionized cleaning to obtain the pressure-sensitive polymer film.

Description

Technical Field

[0001] The present invention belongs to the technical field of flexible pressure sensors, and particularly relates to a pressure-sensitive polymer film, a preparation method thereof, and an application thereof. Background Art

[0002] With the rapid development of wearable technologies, biomedical applications, and smart materials, the integration of flexible sensors into electronic devices has become a research hotspot. Among them, pressure-sensitive materials have received extensive attention due to their key roles in health monitoring, tactile interfaces, industrial applications, and interactive electronic devices. However, traditional pressure-sensitive materials, such as polymer piezoresistive materials and capacitive pressure sensors, still have certain limitations in terms of flexibility, transparency, and response speed. For example, conductive polymer composites (CPCs) used in piezoresistive sensors are prone to mechanical property degradation and limited electrical stability during deformation. At the same time, although piezoelectric sensors have high sensitivity, their materials are usually brittle and difficult to integrate into flexible or transparent devices.

[0003] The patent application with the publication number CN115232478A discloses a Silk / Li+ conductive hydrogel pressure sensor, a construction method thereof, and an application thereof. The Silk / Li+ conductive hydrogel pressure sensor of the present invention is composed of a cross-linked silk fibroin network structure mainly composed of SilkI structure and Li+, and is prepared by a one-pot method or a post-adding method. Lithium bromide in the present invention maintains the stability of the secondary structure of silk fibroin in the silk fibroin hydrogel, mainly maintaining the helical and random coil structures, and does not change into a structure mainly composed of β-sheets with the change of environment and time, so as to maintain the mechanical (mainly elasticity) stability of the silk fibroin conductive hydrogel, that is, it will not become hard over time and lose its elasticity and piezoresistive sensing performance. However, the mechanical properties of the hydrogel pressure sensor disclosed in this patent application need to be improved, and it is prone to degradation.

[0004] The patent application with the publication number CN116144070A discloses a preparation method of a dielectric elastomer material and a pressure sensor. The preparation method of the dielectric elastomer material includes: adding CaCu3Ti4O12 powder and RGO powder into a PDMS prepolymer solution, stirring and mixing evenly to obtain a mixed solution; adding NaCl salt particles into the mixed solution and mixing evenly, then adding a PDMS cross-linking curing agent to obtain a preliminary cured slurry: adding the preliminary cured slurry into a mold of a hot press, pressing the preliminary cured slurry into a film through hot pressing treatment, washing away the NaCl salt particles with water, and then peeling the film from the mold to obtain a porous CaCu3Ti4O12 / RGO / PDMS dielectric elastomer material. However, the adhesion of the pressure sensor disclosed in this patent application needs to be further improved.

[0005] In recent years, materials such as dielectric elastomers and conductive hydrogels have made some progress in the field of flexible pressure sensors, but they still face challenges in adhesion, optical transparency, and long-term stability. For example, although conductive hydrogels have significant advantages in biocompatibility, their applications are often limited due to insufficient mechanical strength and degradation after long-term use. Therefore, there is an urgent need to develop polymer materials with flexibility, optical transparency, and high pressure sensitivity to overcome these technical bottlenecks. Summary of the Invention

[0006] The present invention provides a method for preparing a pressure-sensitive polymer film. The pressure-sensitive polymer material prepared by using this preparation method has flexibility, optical transparency, and high pressure sensitivity.

[0007] The present invention provides a method for preparing a pressure-sensitive polymer film, comprising:

[0008] S1. Add cobalt hexacyanocobaltate ((Co3[Co(CN)6]2(CoCo-PBA)) and propylene oxide to an autoclave, seal the autoclave, and fill it with carbonyl sulfide. After preheating, carry out a copolymerization reaction at 80 - 85 °C. After the reaction is completed, cool it and release carbonyl sulfide to obtain a PPMNTC copolymer;

[0009] S2. Dissolve the PPMNTC copolymer in N,N-dimethylformamide to obtain a spin-coating solution. Spin-coat the spin-coating solution onto a substrate, anneal and cure it, and perform deionized water cleaning to obtain a pressure-sensitive polymer film.

[0010] Through the catalytic action of cobalt hexacyanocobaltate, at a suitable reaction temperature, the present invention conducts a copolymerization reaction by the thiocarbonyl polymerization method. Due to the addition of carbonyl sulfide, the obtained PPMNTC copolymer has a unique sulfur-based chemical structure. The introduction of sulfur not only enhances the adhesion of the material, making it have better adhesion performance on different substrates (such as metals, polymers, and glasses), but also endows the material with excellent elasticity and transparency. Compared with traditional polymers, sulfur-containing polymers and copolymers exhibit stronger adhesion on various surfaces. In addition, materials with thiocarbonate functional groups have been proven to have good pressure sensing capabilities due to their unique dielectric properties, making them ideal candidate materials for flexible pressure sensors. PPMNTC is synthesized by the thiocarbonyl polymerization method, ensuring its highly controllable molecular structure, thereby optimizing the molecular weight distribution and structural uniformity, which are crucial for maintaining the optical transparency and mechanical flexibility of the material.

[0011] Preferably, the mass / volume ratio of cobalt hexacyanocobaltate and propylene oxide is 1:1 to 1:1.5.

[0012] Preferably, the charging amount of carbonyl sulfide is 3.0–5.0 MPa to ensure the smooth progress of the copolymerization reaction, control the molecular weight and structure of the polymer, and optimize its mechanical properties and pressure-sensitive characteristics.

[0013] Preferably, the preheating process is to preheat the autoclave in an oil bath for 10 - 20 min.

[0014] Preferably, the copolymerization reaction time is 2 h - 3 h.

[0015] Preferably, before dissolving the PPMNTC copolymer in N,N-dimethylformamide, dissolve the PPMNTC copolymer in dichloromethane (CH2Cl2). After complete dissolution, add methanol, and the product sinks to the bottom in methanol. After repeated purification, vacuum drying is carried out to obtain the purified PPMNTC copolymer.

[0016] Preferably, the concentration of the PPMNTC copolymer in the spin-coating solution is 10% - 15%, the spinning speed is 1000 - 2000 rpm, and the spinning time is 30 - 60 s.

[0017] Preferably, it is obtained by 1H NMR characterization that the chemical structure of the PPMNTC copolymer is: Among them, a corresponds to -CH (adjacent to the carbonyl C=O), and the chemical shift range is 4.8 - 5.2 ppm; b corresponds to -CH2- (the main-chain methylene, close to sulfur or oxygen), and the chemical shift range is 1.5 - 2.5 ppm; c corresponds to -OCH3 or -OCH2- (the hydrogen in the ether bond environment), and the chemical shift range is 3.0 - 3.1 ppm; d represents the methylene (-O-CH2-) connected to the oxygen bridge, and the signal usually appears at 3.1 - 3.6 ppm; e represents the methylene (-CH2-) adjacent to the sulfur atom (S), usually located between 3.1 - 3.6 ppm; f represents the methylene (-CH3 or -CH2-) far from the carbonyl or oxygen bridge, and the chemical shift is generally between 1.2 - 1.4 ppm. These 1H NMR data jointly verify the successful synthesis and characteristic structure of the PPMNTC copolymer.

[0018] Preferably, it is obtained by 13C NMR characterization that the chemical structure of the PPMNTC copolymer is: Among them, 1 corresponds to the carbonyl carbon (C=O, adjacent to the sulfur atom S), with a chemical shift range of 165 - 170 ppm; 2 corresponds to the methylene carbon (-CH2-, adjacent to the carbonyl in the main chain), with a chemical shift range of 70 - 80 ppm; 3 corresponds to the methylene (-CH2-) in the main chain, with a chemical shift range of 30 - 40 ppm; 4 represents the methylene (-CH2-) far from the carbonyl or oxygen bridge, usually appearing between 15 - 20 ppm; 5 represents the carbon connected to the ether bond (-O-CH2-), and the signal is usually at 73 - 76 ppm; 6 corresponds to the methylene carbon near the oxygen bridge, with a chemical shift between 35 - 37 ppm; 7 represents the carbon further away from the functional group, with a chemical shift usually at 16 - 20 ppm. These 13 13C NMR data jointly verify the successful synthesis of the PPMNTC copolymer and its characteristic structure

[0019] To ensure the best performance of PPMNTC in terms of optical transparency and flexibility, the present invention adopts a strictly controlled polymerization process to optimize the molecular weight distribution in order to obtain a highly uniform molecular structure. This structural uniformity is crucial for the transparency and mechanical flexibility of the material, enabling it to meet the requirements of various applications.

[0020] In addition, the synthesis method is further optimized so that the dielectric properties of PPMNTC can be adjusted, enabling it to be customized for different application scenarios. For example, by adjusting the molecular structure of the polymer, its pressure sensitivity can be optimized, making it perform more excellently in fields such as biomedical sensors or wearable electronic devices.

[0021] On the other hand, the present invention also provides a pressure-sensitive polymer film prepared by the preparation method of the pressure-sensitive polymer film, and the thickness of the pressure-sensitive polymer film is 40 - 80 μm.

[0022] On the other hand, the present invention also provides the application of the pressure-sensitive polymer film in wearable electronic devices, flexible touch panels, biomedical sensors, and industrial pressure sensors.

[0023] The pressure-sensitive polymer film prepared based on the PPMNTC material provided by the present invention has wide application value in multiple fields due to its excellent flexibility, optical transparency, pressure response characteristics, and excellent adhesion, including but not limited to the following aspects:

[0024] Wearable electronic devices: PPMNTC is very suitable for flexible sensors and can be used to monitor physiological parameters in real time, such as pulse, respiration, muscle movement, etc. Due to the high ductility of this polymer (it can be stretched by more than 1000%), it can fit seamlessly to the human body, ensuring stable signal output during exercise and providing efficient data feedback for the health monitoring system.

[0025] Flexible Touch Panel: Due to the excellent pressure response characteristics of PPMNTC, it can be an ideal material for touch display devices. For example, it can be used in touch devices such as smartphones, tablets, and interactive whiteboards to achieve precise pressure sensing input. At the same time, the high transparency of this material (visible light transmittance > 90%) ensures the visual clarity of the touch interface, making it a potential choice for future high-end electronic screens.

[0026] Biomedical Sensors: PPMNTC has excellent biocompatibility and strong adhesion to biological tissues, and is suitable for applications such as wound monitoring patches, prosthetic interfaces, and medical health monitoring systems. Its fast response characteristics and high sensitivity enable it to be used for real-time diagnosis, such as detecting skin pressure changes, evaluating the rehabilitation process, or monitoring the physiological state of patients.

[0027] Industrial Pressure Sensors: PPMNTC can be integrated into flexible electronic circuits to detect mechanical strain and pressure changes in industrial equipment, automotive systems, and robots. Its excellent resistance to dynamic mechanical stress enables it to work stably for a long time in harsh environments. Compared with traditional rigid sensors, PPMNTC has higher reliability in complex environments and can significantly improve the performance of industrial sensing systems.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] The present invention is synthesized by a precisely controlled thiocarbonyl polymerization process. This method introduces monothiocarbonate functional groups during the polymerization process, enabling the propylene monomer to undergo a polymerization reaction in the presence of sulfur (S) element, thereby introducing a sulfur structure into the polymer main chain. The presence of this sulfur element significantly enhances the adhesion and mechanical properties of the polymer, making it have excellent performance in pressure sensing and adhesion applications. Description of the Drawings

[0030] Figure 1 1H Nuclear Magnetic Resonance (1H NMR) spectrum of PPMNTC prepared in Example 1 of the present invention. 1 NMR

[0031] Figure 2 13C Nuclear Magnetic Resonance (13C NMR) spectrum of PPMNTC prepared in Example 1 of the present invention. 1 NMR

[0032] Figure 3 Stress-strain curve, ultraviolet-visible absorption spectrum curve, contact angle test diagram, and flexibility and adhesion diagrams under different finger bending states of the pressure-sensitive film prepared in Example 1 of the present invention.

[0033] Figure 4 Schematic diagram of the pressure sensor device provided in Embodiment 1 of the present invention, graph of the capacitance response of the pressure sensor device to small pressure changes (0.2 kPa to 1 kPa) over time, capacitance response of the pressure sensor device to larger pressure changes (10 kPa to 100 kPa) over time, detection limit (LOD) graph of the pressure sensor device, and sensitivity curve graph of the pressure sensor device. Detailed implementation manners

[0034] The PPMNTC provided in the specific embodiments of the present invention has excellent mechanical flexibility and high ductility. Its elongation at break exceeds 1000%, and it can withstand significant mechanical deformations, still maintaining stable performance even under repeated stretching and bending. This characteristic ensures the long-term reliability of the material in wearable sensors and flexible electronic devices, enabling it to meet the application requirements in dynamic environments.

[0035] The PPMNTC provided in the specific embodiments of the present invention has excellent optical transparency, with a light transmittance exceeding 90% in the visible spectrum range, making it an ideal choice for application fields with high requirements for optical clarity, such as touchscreens, smart displays, and health monitoring devices. The high transparency not only improves the display effect but also ensures real-time monitoring by the sensor without affecting the visual experience.

[0036] The PPMNTC provided in the specific embodiments of the present invention exhibits strong adhesion and can firmly adhere to the surfaces of various substrates such as glass, metal, and polymers without the need for additional adhesives. This characteristic greatly simplifies the manufacturing process, reduces production costs, and improves the overall stability of the device, making it more advantageous in flexible electronics manufacturing and integrated systems.

[0037] This material has excellent pressure sensitivity, with a sensitivity of up to 0.3 kPa-1, and can provide high-precision pressure sensing in a wide pressure range from 0.2 kPa to 100 kPa. This wide operating pressure range makes PPMNTC suitable for both ultra-sensitive touch sensors and high-pressure monitoring systems, capable of meeting various application requirements from light touch detection to high-load induction.

[0038] In addition, PPMNTC also has an ultra-fast response speed, with its response time in the millisecond level, ensuring real-time detection of pressure changes. This characteristic makes it particularly suitable for dynamic and interactive applications, such as smart interaction interfaces, tactile feedback systems, and high-precision health monitoring devices, showing significant advantages in application scenarios that require fast signal processing.

[0039] Embodiment 1

[0040] Transfer a 20 mL autoclave equipped with a magnetic stirrer into the glove box, and add 2 mL of the heterogeneous catalyst cobalt hexacyanocobaltate (Co3[Co(CN)6]2) (CoCo-PBA), followed by the addition of 2.0 mL of propylene oxide (PO).

[0041] After sealing the autoclave, remove it from the glove box and add 4.0 MPa of unreacted carbonyl sulfide (COS).

[0042] Then, immerse the reaction kettle in an oil bath preheated to 80 °C and carry out the copolymerization reaction at 85 °C for 12 hours. After the reaction is completed, the reaction kettle is cooled with an ice-water bath and the COS is released.

[0043] Take a portion of the crude product for 1H NMR analysis to verify the polymer structure, as Figure 1 shown, where a corresponds to -CH (adjacent to the carbonyl C=O), with a chemical shift range of 4.8 - 5.2 ppm; b corresponds to -CH2- (main chain methylene, close to sulfur or oxygen), with a chemical shift range of 1.5 - 2.5 ppm; c corresponds to -OCH3 or -OCH2- (hydrogen in the ether bond environment), with a chemical shift range of 3.0 - 3.1 ppm; d represents the methylene group (-O-CH2-) connected to the oxygen bridge, and the signal usually appears at 3.1 - 3.6 ppm; e represents the methylene group (-CH2-) adjacent to the sulfur atom (S), usually located between 3.1 - 3.6 ppm; f represents the methylene group (-CH3 or -CH2-) far from the carbonyl or oxygen bridge, and the chemical shift is generally between 1.2 - 1.4 ppm. These 1H NMR data jointly verify the successful synthesis of the PPMNTC copolymer and its characteristic structure.

[0044] Subsequently, dissolve the crude product in 10 mL of dichloromethane (CH2Cl2) and precipitate it in 200 mL of methanol. This process is repeated three times. The resulting white precipitate is collected and vacuum dried at 60 °C to a constant weight. The purified PPMNTC copolymer is further characterized by 13C NMR, as Figure 2 shown, where 1 corresponds to the carbonyl carbon (C=O, adjacent to the sulfur atom S), with a chemical shift range of 165 - 170 ppm; 2 corresponds to the methylene carbon (-CH2-, main chain adjacent to the carbonyl), with a chemical shift range of 70 - 80 ppm; 3 corresponds to the methylene group (-CH2-) in the main chain, with a chemical shift range of 30 - 40 ppm; 4 represents the methylene group (-CH2-) far from the carbonyl or oxygen bridge, usually appearing between 15 - 20 ppm; 5 represents the carbon connected to the ether bond (-O-CH2-), and the signal is usually at 73 - 76 ppm; 6 corresponds to the methylene carbon near the oxygen bridge, with a chemical shift between 35 - 37 ppm; 7 represents the carbon further away from the functional group, and the chemical shift is usually between 16 - 20 ppm. These 13The 13C NMR data jointly verified the successful synthesis and characteristic structure of the PPMNTC copolymer.

[0045] First, the PPMNTC copolymer was dissolved in N,N-dimethylformamide (DMF) at a concentration of 22.5%. Then, the resulting solution was spin-coated onto a glass substrate at a rotational speed of 1000 rpm for the same time to prepare a thinner and more uniformly distributed film. After spin-coating, all the films were annealed at 120 °C for 2 hours to stabilize the polymer structure, and then washed with deionized (DI) water to remove the residual DMF. Finally, the films were dried in an oven at 80 °C for 2 hours to remove the residual moisture, and a pressure-sensitive polymer film with a stable thickness of 80 μm was finally obtained.

[0046] As Figure 3 Figure a shows the stress-strain curve of the pressure-sensitive polymer film prepared in this example. It can be seen that the film still maintains a high mechanical strength at high strain (close to 1500%), showing good tensile properties and toughness, and can be used for flexible sensing applications in high-deformation environments.

[0047] As Figure 3 Figure b shows the ultraviolet-visible absorption spectrum of the pressure-sensitive polymer film prepared in this example. It can be seen that the film has obvious absorption peaks in the ultraviolet region (about 200 - 400 nm) and maintains a high transmittance in the visible region (400 - 800 nm), indicating its certain optical transparency and suitability for transparent electronic devices or wearable sensors.

[0048] As Figure 3 Figure c shows the contact angle test of the pressure-sensitive polymer film prepared in this example. It can be seen that its water contact angle is about 85°, indicating that the film surface has moderate hydrophilicity, which can not only ensure a certain surface wettability but also still have good stain resistance, and is suitable for applications in flexible sensors and wearable electronic devices.

[0049] As Figure 3 Figures d, e, and f show the flexibility and adhesion of the pressure-sensitive polymer film prepared in this example under different finger bending states. It can be seen that the film can maintain its integrity under large bending deformations and can adhere well to the skin or glove surface, demonstrating its smooth texture, durability, and potential for wearable sensing applications.

[0050] As Figure 4 Figure a shows a schematic diagram of a pressure sensor device composed of copper (Cu) and a pressure-sensitive polymer film, with a layer of pressure-sensitive polymer film sandwiched between two copper layers.

[0051] As Figure 4The capacitance response of the pressure sensor device shown in b to small pressure changes (0.2 kPa to 1 kPa) over time shows that the device has high sensitivity and good resolution in the low pressure range, can clearly distinguish small pressure changes, and is suitable for applications such as light touch or low force detection.

[0052] As Figure 4 The capacitance response of the pressure sensor device shown in c to larger pressure changes (10 kPa to 100 kPa) over time shows that the device has stability and a wide dynamic range in the large pressure range, can accurately sense large pressure loads, and is suitable for high stress environments or high force sensing scenarios.

[0053] As Figure 4 The detection limit (LOD) of the pressure sensor device shown in d demonstrates its strong sensitivity to small pressure changes.

[0054] As Figure 4 The sensitivity curve of the pressure sensor device shown in e shows the change in the capacitance change rate (ΔC / C0) with the applied pressure, which includes sensitivity coefficients S1, S2, and S3. The sensitivity coefficient in the small pressure range is 0.033 kPa -1 , while the sensitivity coefficient in the large pressure range is 0.306 kPa -1 . These results indicate that PPMNTC can be used for flexible, highly sensitive pressure sensor devices, enabling high response performance over a wide pressure range.

[0055] Example 2

[0056] Different from Example 1 are the contents of each component and the addition amount of carbonyl sulfide (COS).

[0057] Transfer a 20 mL autoclave equipped with a magnetic stirrer into the glove box, add 2.0 mL of the heterogeneous catalyst cobalt hexacyanocobaltate (Co3[Co(CN)6]2) (CoCo-PBA), and then add 2.5 mL of propylene oxide (PO).

[0058] After sealing the autoclave, remove it from the glove box and add 4.5 MPa of unreacted carbonyl sulfide (COS). Then, immerse the reaction kettle in an oil bath preheated to 80 °C and carry out the copolymerization reaction at 85 °C for 12 hours. After the reaction is completed, cool the reaction kettle with an ice-water bath and release COS.

[0059] A portion of the crude product was subjected to 1H NMR analysis to verify the polymer structure. Subsequently, the crude product was dissolved in 10 mL of dichloromethane (CH2Cl2) and precipitated in 200 mL of methanol, and this process was repeated three times. The resulting white precipitate was collected and dried under vacuum at 60 °C to a constant weight. The purified PPMNTC copolymer was further characterized by 13C NMR to confirm its chemical structure.

[0060] The PPMNTC copolymer was dissolved in N,N-dimethylformamide (DMF) to a concentration of 22.5%, and then the resulting solution was spin-coated onto a glass substrate at a spin-coating speed of 1000 rpm for 30 seconds to obtain a uniform thin film. After spin-coating, all the thin films were annealed at 120 °C for 2 hours to stabilize the polymer structure, and then washed with deionized (DI) water to remove the residual DMF. Finally, the thin films were dried in an oven at 80 °C for 2 hours to finally obtain the pressure-sensitive polymer thin films.

[0061] Example 3

[0062] Different from Example 1, the spin-coating speed was 2000 rpm and the spin-coating time was 60 s.

[0063] PPMNTC (polypropylene monothiocarbonate) provided by the specific embodiments of the present invention has become a very promising candidate material due to its unique sulfur-based chemical structure and mechanically stable main-chain structure. The introduction of sulfur not only enhances the adhesion of the material, making it have better adhesion performance on different substrates (such as metals, polymers, and glass), but also endows the material with excellent elasticity and transparency. A series of studies have shown that compared with traditional polymers, sulfur-containing polymers and copolymers exhibit stronger adhesion on various surfaces. In addition, materials with thiocarbonate functional groups have been proven to have good pressure-sensing ability due to their unique dielectric properties, making them ideal candidates for flexible pressure sensors. PPMNTC is synthesized by the thiocarbonyl polymerization method, ensuring its highly controllable molecular structure, thereby optimizing the molecular weight distribution and structural uniformity, which are crucial for maintaining the optical transparency and mechanical flexibility of the material.

[0064] In a specific embodiment of the present invention, a high-performance and multifunctional material, PPMNTC, is introduced. This material combines flexibility, optical transparency, excellent adhesion, and outstanding pressure sensitivity. These unique properties make it an ideal choice for multiple fields such as wearable electronic devices, biomedical sensors, and industrial monitoring systems. The development of PPMNTC represents a major breakthrough in flexible electronics and pressure sensing technology, effectively overcoming the limitations of traditional materials in terms of mechanical properties, pressure response, and adhesion characteristics. Its adjustable mechanical properties, electrical response, and attachment characteristics enable it to be applicable to various application scenarios such as smart materials, biomedical devices, and interactive electronic systems. The versatility of PPMNTC makes it a key material for next-generation pressure-sensitive devices and intelligent technologies, capable of meeting the growing demands of modern healthcare systems and electronic devices, providing a new solution for the development of intelligent sensing, real-time monitoring, and flexible electronics, and leading the development direction of a new generation of intelligent materials.

Claims

1. A method for preparing a pressure-sensitive polymer film, characterized in that, Comprising: S1. Add cobalt hexacyanocobaltate and propylene oxide into an autoclave, seal the autoclave, and fill it with carbonyl sulfide. After preheating, carry out copolymerization reaction at 80 - 85 °C. After the reaction is completed, cool it and release carbonyl sulfide to obtain a PPMNTC copolymer; S2. Dissolve the PPMNTC copolymer in N,N-dimethylformamide to obtain a spin coating solution. Spin coat the spin coating solution onto a substrate, anneal and cure it, and clean it with deionized water to obtain a pressure-sensitive polymer film.

2. The preparation method of the pressure-sensitive polymer film according to claim 1, characterized in that, The volume ratio of the cobalt hexacyanocobaltate to the propylene oxide is 1:1 - 1:1.

5.

3. The preparation method of the pressure-sensitive polymer film according to claim 1, characterized in that, The filling amount of the carbonyl sulfide is 3.0–5.0 MPa.

4. The preparation method of the pressure-sensitive polymer film according to claim 1, characterized in that The preheating process is to preheat the autoclave in an oil bath for 10 - 20 min.

5. The method for preparing a pressure-sensitive polymer film according to claim 1, characterized in that, The time of the copolymerization reaction is 2 h - 3 h.

6. The method for preparing the pressure-sensitive polymer film according to claim 1, wherein, The concentration of the PPMNTC copolymer in the spin coating solution is 10% - 15%, the spinning speed is 1000 - 2000 rpm, and the spinning time is 30 - 60 s.

7. The method for preparing the pressure-sensitive polymer film according to claim 1, wherein The chemical structure of the PPMNTC copolymer was characterized by ^1H NMR as follows: where a is -CH, b is -CH2-, c is -OCH3 or -OCH2-, d is -O-CH2-, e is -CH2-, and f is -CH3 or -CH2-.

8. A pressure-sensitive polymer film, characterized in that, Prepared by the preparation method of the pressure-sensitive polymer film according to any one of claims 1 - 7, and the thickness of the pressure-sensitive polymer film is 40 - 80 μm.

9. An application of the pressure-sensitive polymer film according to claim 8 in wearable electronic devices, flexible touch panels, biomedical sensors, and industrial pressure sensors.

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