A method for preparing nanoscroll films using a one-pot incubation method

Abstract

The application discloses a method for preparing nanosheet crystal bundle film by using a one-pot incubation method, which comprises the following steps: preparing a base solution, adding a spin-coatable polymer into a solvent, stirring and dissolving to prepare a polymer base solution; spin-coating the polymer base; preparing an incubation solution; adding the polymer base into the incubation solution; and cooling and inducing crystallization to obtain a polymer film containing polymer nanosheet crystals. According to the application, a simple incubation solution is prepared, and then solution incubation is carried out on a suitable base, so that the nanosheet crystal film can be prepared by using only a common oil bath device without modifying the device and by following a conventional solution incubation process. The preparation condition of the application is easy to meet, and a common homogenizer can meet the rotation speed requirement without using a high-speed motor. The preparation method of the application is extremely simple and easy to implement, and can be more suitable for large-scale nanosheet crystal production.

Description

Technical Field

[0001] This invention relates to the preparation of polymer nanosheet crystalline films, belonging to the field of nanomaterials technology, and specifically to a method for preparing nanosheet crystalline bundle films using a one-pot incubation method. Background Technology

[0002] The crystal structure and molecular chain orientation of semi-crystalline polymers have a significant impact on the final properties of polymer products. The crystallization process of polymers is similar to that of small molecules, including the formation of polymer nuclei and the growth of grains (J. Am. Chem. Soc. 2022, 144, 17576-17587. ACS Macro. Lett. 2022, 11, 284-288). Based on the presence or absence of heterogeneous interfaces during crystallization, polymer nucleation can be classified into homogeneous nucleation and heterogeneous nucleation (Progress in Polymer Science 2021, 115, 101376). Homogeneous nucleation refers to the formation of ordered chain bundles within the polymer bulk through thermal motion, which serve as crystal nuclei; heterogeneous nucleation refers to the formation of crystal nuclei by the ordered arrangement of polymer molecular chains or segments on the surface of a foreign substance. The foreign substance can be impurities, nucleating agents, or other fillers. Furthermore, when crystal nuclei remain in a polymer without complete melting or dissolution, polymer molecular chains or segments will nucleate and crystallize attached to these nuclei. This special nucleation and crystallization method is called self-nucleation. Generally, when polymers crystallize via homogeneous nucleation, a large degree of supercooling is required, the number of nuclei is small, the nucleation rate is slow, the spherulites are large, and the polymer crystallinity is low, resulting in poor performance of the finished product. When fillers or nucleating agents are added to the polymer matrix, polymer molecular chains or segments rapidly nucleate and crystallize on the surface of the nucleating agent, producing small, uniformly distributed crystals. This improves the crystallinity of the polymer and enhances the properties of the polymer matrix (Adv. Mater. Inter. 2021, 8, 2001894).

[0003] Currently reported semi-crystalline polymers such as polyethylene, isotactic polypropylene, polyamide, and polyetheretherketone can form transverse crystalline structures on the surface of reinforcing fibers (such as glass fibers, carbon fibers, polytetrafluoroethylene fibers, polyolefin fibers, and aramid fibers) through stress-induced or impurity-induced growth (Macromolecules 2021, 54, 9100-9112. Macromolecules 2018, 51, 4865-4873). Hybrid tandem structures can also be formed on electrospun nanofibers through vapor deposition, solvent evaporation, and thin-film induced crystallization (Nanoscale, 2019, 11, 16788). There are currently no reported studies on the growth of lamellar bundle structures on polymer film substrates. Summary of the Invention

[0004] The purpose of this invention is to provide a simple solution incubation method for preparing and collecting nanosheet crystals on a polymer film, thereby further expanding the application of polymer films containing polymer sheet crystals in fields such as self-powered sensing.

[0005] Specifically, the present invention is implemented using the following technical solution:

[0006] A method for preparing nanosheet crystal beam films using a one-pot incubation method includes the following steps:

[0007] (1) Preparation of base solution: Add the spin-coated polymer to the solvent, stir to dissolve, and prepare the polymer base solution;

[0008] (2) Spin-coating polymer substrate: The polymer substrate solution is dropped onto the substrate, spin-coated using a spin coater, and dried to obtain the polymer substrate;

[0009] (3) Preparation of incubation solution: Add the semi-crystalline polymer to the incubation solvent, heat to dissolve, and obtain the incubation solution;

[0010] (4) One-pot incubation: Add the polymer substrate from step (2) to the incubation solution, cool down to induce crystallization, and obtain a polymer film containing polymer flakes.

[0011] In the above-described method, preferably, the spin-coatable polymer in step (1) includes one of polyamide (PA), polyvinylidene fluoride (PVDF), and polyvinyl alcohol (PVA), and the solvent is one of formic acid, N,N-dimethylformamide, and water.

[0012] The concentration of the substrate solution in step (1) is 5-25 wt%.

[0013] In the above-described method, preferably, step (2) of spin coating using a spin coater involves using a disposable dropper to apply the substrate solution onto the collecting substrate, with a spin coating time of 10-100 s, a spin coating speed of 200 rpm-2000 rpm, and an acceleration of 100-1000 rpm / s. Simultaneously, the size of the acrylic sheet in step (2) can be manually controlled using a cutting machine.

[0014] In the above-described method, preferably, the semi-crystalline polymer in step (3) is selected from one of polyamide (PA), polyvinylidene fluoride (PVDF), polycaprolactone (PCL), and polylactic acid (PLA), and the incubation solvent is selected from one of glycerol, 1,4-butanediol, toluene, ethylene glycol, N,N-dimethylformamide (DMF), chlorobenzene, glacial acetic acid, water, and xylene. The concentration of the incubation solution in step (3) is preferably 0.005-0.5 wt%, more preferably 0.05-0.5 wt%. The heating and dissolving temperature in step (3) can be controlled by a conventional heating device. The cooling and crystallization temperature in step (4) can be controlled by an oil bath.

[0015] In the above-described method, as a preferred embodiment, it can be a method including the following steps:

[0016] (1) Preparation of base solution: Add PA66 to formic acid, stir to dissolve, and obtain a base solution with a concentration of 10-20 wt%;

[0017] (2) Spin-coating polymer substrate: The substrate solution is dropped onto an acrylic plate and spin-coated using a spin coater. The polymer substrate is then dried to obtain the substrate.

[0018] (3) Preparation of incubation solution: Add PA66 to ethylene glycol and heat to 160-220℃ to dissolve for 0.5-2h to obtain an incubation solution with a concentration of 0.01-0.3 wt%;

[0019] (4) One-pot incubation: Add the polymer substrate from step (2) to the incubation solution, cool to 130-150℃ to induce crystallization for 10-60 min, and obtain a PA66 spin-coated film containing PA66 flakes.

[0020] In the above-described method, the substrate solution concentration in step (1) is preferably 12-16 wt%. The inventors have found that if the substrate solution concentration is too low, a complete film cannot be formed during spin coating, while if the concentration is too high, it is difficult to dissolve and the viscosity is too high, resulting in an uneven spin-coated film. Preferably, in step (2), the spin coating speed is 500-1500 rpm, the acceleration is 300-800 rpm / s, and the spin coating time is 30-80s; more preferably, the spin coating speed is 1000 rpm, the acceleration is 500 rpm / s, and the spin coating time is 60s. The drying temperature in step (2) is not particularly required and can be 20-80℃. In step (3), the incubation solution concentration is preferably 0.12-0.26 wt%. In step (4), it is preferable to cool to 130-150℃ to induce crystallization for 20-40 minutes. The inventors discovered that the incubation solution must be a freshly prepared solution. If the PA66 in the incubation solution has already crystallized, lamellar bundles will not grow on the PA66 substrate.

[0021] The above technical solution involves placing a spin-coated substrate in an incubation solution for cooling and crystallization, thereby growing lamellar bundles on the polymer substrate. The crystallization process of the polymer is similar to that of small molecules, including the formation of polymer nuclei and the growth of grains.

[0022] Lamellar nucleation mechanism: After the polymer spin-coated film is cured by a drying process, spherulites form due to rotational shearing. The low interfacial potential energy of the spherulites provides a good chain template for polymer nucleation and crystallization. On the one hand, due to lattice matching effect and stirring induction, polymer molecular chains nucleate on the polymer spin-coated film substrate. On the other hand, the groups on the polymer molecular chains have a strong polar tendency, causing the macromolecular chains to crystallize along the directional direction through hydrogen bonding, which is conducive to the formation of lamellar crystals of different sizes and shapes.

[0023] Lamellar crystal growth mechanism: Polymer molecular chains crystallize radially from the nucleation point. At this stage, polymer lamellar crystals grow in one dimension. Under stirring induction, the growth of polymer lamellar crystals changes from one-dimensional to two-dimensional. The inventors discovered that, influenced by incubation conditions such as temperature and lattice matching, the method of this invention can achieve the formation of polymer lamellar crystals such as PA, PVDF, PCL, and PLA on the surface of PA, PVDF, and PVA. The formation of lamellar crystals is caused by incubation conditions such as the incubation solution; the polymer substrate merely serves as a collecting film for the lamellar crystals. In use, the polymer substrate can be peeled off from the substrate acrylic plate.

[0024] As described above, the technical solution of this invention uses readily available raw materials and is simple to implement. A polymer spin-coated film containing polymer flakes can be prepared using a one-pot incubation method. Furthermore, this invention broadens the scope of polymer crystal growth on polymers, thereby enabling the large-scale production of polyamide 66 spin-coated films containing polyamide 66 flakes. This makes it more suitable for self-powered sensors and for the fabrication of triboelectric nanogenerators. Triboelectric nanogenerators generally operate at high voltage and low current, making them suitable for sensor applications.

[0025] This invention involves preparing a simple incubation solution and then incubating it on a suitable substrate. The nanosheet crystalline film can be prepared and collected using only a standard oil bath apparatus without any modification to the existing equipment, following a conventional solution incubation process. The preparation conditions of this invention are easy to meet; a standard homogenizer can satisfy the required rotational speed, eliminating the need for a high-speed motor. The preparation method of this invention is extremely simple and easy to implement, making it highly suitable for large-scale production of nanosheet crystals. Attached Figure Description

[0026] Figure 1This is a schematic diagram of a polymer film containing lamellar crystals. In the diagram: 1—polyamide 66 lamellar bundles, 2—polyamide 66 spin-coated film. Lamellar crystals are a prerequisite for the formation of lamellar bundles, and nanolamellar bundles are the components of nanolamellar crystals. They grow on the polymer film without overlap.

[0027] Figure 2 This is a scanning electron microscope image of the polymer sheet crystal bundle film prepared in Example 1.

[0028] Figure 3 This is a scanning electron microscope image of the polymer sheet crystal bundle film prepared in Example 2.

[0029] Figure 4 This is a scanning electron microscope image of the polymer sheet crystal bundle film prepared in Example 3.

[0030] Figure 5 This is a scanning electron microscope image of the polymer sheet crystal bundle film prepared in Example 4.

[0031] Figure 6 This is a scanning electron microscope image of the polymer sheet crystal bundle film prepared in Example 5.

[0032] Figure 7 This is a scanning electron microscope image of the polymer sheet crystal bundle film prepared in Example 6.

[0033] Figure 8 This is a scanning electron microscope image of the polymer sheet crystal bundle film prepared in Example 7.

[0034] Figure 9 The diagram shows the triboelectric nanogenerator application test using the nanosheet crystal bundle film of Example 4 and the comparative nylon 66 film. Detailed Implementation

[0035] The following embodiments are further illustrations of the present invention and serve as explanations of the technical content of the present invention. However, the essence of the present invention is not limited to the embodiments described below. Those skilled in the art can and should know that any simple changes or substitutions based on the spirit of the present invention should fall within the protection scope claimed by the present invention.

[0036] Example 1:

[0037] The specific steps for preparing nanosheet beam films using the one-pot incubation method are as follows:

[0038] (1) Preparation of base solution: Weigh 14 g of polyamide 66 (PA66, nylon 66) and add it to 86 g of formic acid (mass fraction: 88%). Stir magnetically for 12 h at room temperature to obtain a uniformly dispersed 14 wt% PA66-formic acid spinning solution.

[0039] (2) Spin-coating polymer substrate: 2 ml of the polymer substrate was spin-coated onto a 4 cm*4 cm acrylic plate using a disposable dropper. The spin-coating speed was 1000 rpm, the acceleration was 500 rpm / s, and the spin-coating time was 60 s. PA66 spin-coated film was prepared as the substrate.

[0040] (3) Preparation of incubation solution: Add 0.01 g PA66 particles to 99.99 g ethylene glycol (EG), heat to 190℃ and dissolve for 1 h to obtain 0.01 wt% PA66-EG incubation solution;

[0041] (4) One-pot incubation: Add the PA66 spin-coated film to the incubation solution, cool to 140℃, and crystallize for 30 min to obtain a PA66 spin-coated film containing PA66 flakes.

[0042] Example 2:

[0043] The specific steps for preparing nanosheet beam films using the one-pot incubation method are as follows:

[0044] (1) Preparation of base solution: Weigh 14 g of polyamide 66 (PA66) and add it to 86 g of formic acid (mass fraction: 88%). Stir magnetically for 12 h at room temperature to obtain a uniformly dispersed 14 wt% PA66-formic acid spinning solution.

[0045] (2) Spin-coating polymer substrate: 2 ml of the polymer substrate was spin-coated onto a 4 cm*4 cm acrylic plate using a disposable dropper. The spin-coating speed was 1000 rpm, the acceleration was 500 rpm / s, and the spin-coating time was 60 s. PA66 spin-coated film was prepared as the substrate.

[0046] (3) Preparation of incubation solution: Add 0.05 g PA66 particles to 99.95 g ethylene glycol (EG), heat to 190℃ and dissolve for 1 h to obtain 0.05 wt% PA66-EG incubation solution;

[0047] (4) One-pot incubation: Add the PA66 spin-coated film to the incubation solution, cool to 140℃, and crystallize for 30 min to obtain a PA66 spin-coated film containing PA66 flakes.

[0048] Example 3:

[0049] The specific steps for preparing nanosheet beam films using the one-pot incubation method are as follows:

[0050] (1) Preparation of base solution: Weigh 14 g of polyamide 66 (PA66) and add it to 86 g of formic acid (mass fraction: 88%). Stir magnetically for 12 h at room temperature to obtain a uniformly dispersed 14 wt% PA66-formic acid spinning solution.

[0051] (2) Spin-coating polymer substrate: 2 ml of the polymer substrate was spin-coated onto a 4 cm*4 cm acrylic plate using a disposable dropper. The spin-coating speed was 1000 rpm, the acceleration was 500 rpm / s, and the spin-coating time was 60 s. PA66 spin-coated film was prepared as the substrate.

[0052] (3) Preparation of incubation solution: Add 0.1 g PA66 particles to 99.9 g ethylene glycol (EG), heat to 190℃ and dissolve for 1 h to obtain 0.1 wt% PA66-EG incubation solution;

[0053] (4) One-pot incubation: Add the PA66 spin-coated film to the incubation solution, cool to 140℃, and crystallize for 30 min to obtain a PA66 spin-coated film containing PA66 flakes.

[0054] Example 4:

[0055] The specific steps for preparing nanosheet beam films using the one-pot incubation method are as follows:

[0056] (1) Preparation of base solution: Weigh 14 g of polyamide 66 (PA66) and add it to 86 g of formic acid (mass fraction: 88%). Stir magnetically for 12 h at room temperature to obtain a uniformly dispersed 14 wt% PA66-formic acid spinning solution.

[0057] (2) Spin-coating polymer substrate: 2 ml of the polymer substrate was spin-coated onto a 4 cm*4 cm acrylic plate using a disposable dropper. The spin-coating speed was 1000 rpm, the acceleration was 500 rpm / s, and the spin-coating time was 60 s. PA66 spin-coated film was prepared as the substrate.

[0058] (3) Preparation of incubation solution: Add 0.2 g PA66 particles to 99.8 g ethylene glycol (EG), heat to 190℃ and dissolve for 1 h to obtain 0.2 wt% PA66-EG incubation solution;

[0059] (4) One-pot incubation: After cooling to 140℃, the PA66 spin-coated film is quickly added to the freshly prepared incubation solution and crystallized for 30 min to obtain a PA66 spin-coated film containing PA66 flakes.

[0060] Comparative Example

[0061] (1) Preparation of base solution: Weigh 14 g of polyamide 66 (PA66) and add it to 86 g of formic acid (mass fraction: 88%). Stir magnetically for 12 h at room temperature to obtain a uniformly dispersed 14 wt% PA66-formic acid spinning solution.

[0062] (2) Spin-coating polymer substrate: Take 2 ml with a disposable dropper and drop it onto a 4 cm*4 cm acrylic plate for spin coating. The spin coating speed is 1000 rpm, the acceleration is 500 rpm / s, and the spin coating time is 60 s to prepare a PA66 spin-coated film (without PA66 flakes).

[0063] Example 5:

[0064] The specific steps for preparing nanosheet beam films using the one-pot incubation method are as follows:

[0065] (1) Preparation of base solution: Weigh 14 g of polyamide 66 (PA66) and add it to 86 g of formic acid (mass fraction: 88%). Stir magnetically for 12 h at room temperature to obtain a uniformly dispersed 14 wt% PA66-formic acid spinning solution.

[0066] (2) Spin-coating polymer substrate: 2 ml of the polymer substrate was spin-coated onto a 4 cm*4 cm acrylic plate using a disposable dropper. The spin-coating speed was 1000 rpm, the acceleration was 500 rpm / s, and the spin-coating time was 60 s. PA66 spin-coated film was prepared as the substrate.

[0067] (3) Preparation of incubation solution: Add 0.3 g PA66 particles to 99.7 g ethylene glycol (EG), heat to 190℃ and dissolve for 1 h to obtain 0.3 wt% PA66-EG incubation solution;

[0068] (4) One-pot incubation: Add the PA66 spin-coated film to the incubation solution, cool to 140℃, and crystallize for 30 min to obtain a PA66 spin-coated film containing PA66 flakes.

[0069] Example 6:

[0070] The specific steps for preparing nanosheet beam films using the one-pot incubation method are as follows:

[0071] (1) Preparation of base solution: Weigh 14 g of polyamide 66 (PA66) and add it to 86 g of formic acid (mass fraction: 88%). Stir magnetically for 12 h at room temperature to obtain a uniformly dispersed 14 wt% PA66-formic acid spinning solution.

[0072] (2) Spin-coating polymer substrate: 2 ml of the polymer substrate was spin-coated onto a 4 cm*4 cm acrylic plate using a disposable dropper. The spin-coating speed was 1000 rpm, the acceleration was 500 rpm / s, and the spin-coating time was 60 s. PA66 spin-coated film was prepared as the substrate.

[0073] (3) Preparation of incubation solution: Add 0.2 g PA66 particles to 99.8 g ethylene glycol (EG), heat to 190℃ and dissolve for 1 h to obtain 0.2 wt% PA66-EG incubation solution;

[0074] (4) One-pot incubation: Add the PA66 spin-coated film to the incubation solution, cool to 130℃, and crystallize for 30 min to obtain a PA66 spin-coated film containing PA66 flakes.

[0075] Example 7:

[0076] The specific steps for preparing nanosheet beam films using the one-pot incubation method are as follows:

[0077] (1) Preparation of base solution: Weigh 14 g of polyamide 66 (PA66) and add it to 86 g of formic acid (mass fraction: 88%). Stir magnetically for 12 h at room temperature to obtain a uniformly dispersed 14 wt% PA66-formic acid spinning solution.

[0078] (2) Spin-coating polymer substrate: 2 ml of the polymer substrate was spin-coated onto a 4 cm*4 cm acrylic plate using a disposable dropper. The spin-coating speed was 1000 rpm, the acceleration was 500 rpm / s, and the spin-coating time was 60 s. PA66 spin-coated film was prepared as the substrate.

[0079] (3) Preparation of incubation solution: Add 0.2 g PA66 particles to 99.8 g ethylene glycol (EG), heat to 190℃ and dissolve for 1 h to obtain 0.2 wt% PA66-EG incubation solution;

[0080] (4) One-pot incubation: Add the PA66 spin-coated film to the incubation solution, cool to 150℃, and crystallize for 30 min to obtain a PA66 spin-coated film containing PA66 flakes.

[0081] The PA66 spin-coated films containing PA66 flakes prepared in Examples 1-7 were observed by scanning electron microscopy. Figure 2-7 The images shown are scanning electron microscope (SEM) images of the PA66 spin-coated films containing PA66 lamellae prepared in Examples 1-6, respectively. The PA66 spin-coated film containing PA66 lamellae prepared in Example 4 (…). Figure 5 The surface has a large number of PA66 nanosheets blooming. Example 1 ( Figure 2 Example 2 (1) is based on Example 4, but the incubation concentration is reduced to 0.01 wt%, and the PA66 crystal bundles grown on the surface of the spin-coated PA66 film are small and short; Example 2 (2) Figure 3Example 3 (1) was based on Example 4, but the incubation concentration was reduced to 0.05 wt%. The PA66 lamellar bundles grown on the surface of the spin-coated film changed from a fluffy shape to a ribbon shape. Although the shape changed, the number of lamellars grown was still not high. Figure 4 Example 5 (Based on Example 4) reduced the incubation concentration to 0.1 wt%. The PA66 crystal bundles grown on the PA66 spin-coated film surface changed from a ribbon-like shape to a sheet-like shape. However, most of the grown nanosheets grew laterally, with only a portion growing longitudinally. Figure 6 Example 6 (Based on Example 4, the incubation concentration was increased to 0.3 wt%, and the PA66 crystal bundles disappeared, showing a tendency to form spherulites.) Figure 7 Example 7 (Based on Example 4, the incubation temperature was lowered to 130°C. The PA66 spin-coated film had many burrs, which were small bundles of PA66 crystals. At this point, most of the PA66 in the incubation solution had crystallized.) Figure 8 Based on Example 4, the incubation temperature was increased to 150°C. The morphology of the grown PA66 flakes did not change significantly, but lateral growth was more pronounced. Combining Examples 1, 2, 3, 4, and 5, the method of this invention can prepare PA66 spin-coated films containing PA66 flakes within a relatively wide concentration range. Although the concentration of the incubation solution may alter the prepared PA66 flakes, it will not affect the PA66 spin-coated film itself. Combining Examples 4, 6, and 7, the method of this invention can prepare PA66 spin-coated films containing PA66 flakes within a relatively wide temperature range.

[0082] Application examples

[0083] like Figure 9 As shown, a membrane contact separation triboelectric power generation experiment was conducted using a comparative example nylon 66 (PA66) spin-coated film as the positive electrode and a polytetrafluoroethylene (PTFE) film as the negative electrode. The positive and negative electrode films were placed on the left and right palms respectively and rubbed together. A linear motor was used for rubbing at a frequency of 2Hz (10 rubs in 5 seconds). The voltage output after 10 rubs was demonstrated. Simultaneously, the nanosheet crystal bundle film from Example 4 was used as the positive electrode, and under the same conditions, the voltage output after 10 rubs was also demonstrated. Figure 9 Experiments have shown that although nylon 66 films can also generate electricity through triboelectricity, their output is relatively low. However, growing PA66 crystal bundles on PA66 spin-coated films can significantly improve the voltage output of triboelectric nanogenerators, making them more suitable for use in self-powered sensors.

[0084] It should be noted that the above-described technical content of this invention is merely an explanation and clarification to enable those skilled in the art to understand the technical essence of this invention, and therefore is not intended to limit the scope of protection of this invention. The scope of protection of this invention should be determined by the claims. Those skilled in the art should understand that any modifications, equivalent substitutions, and improvements made based on the essential spirit of this invention should be within the scope of protection of this invention.

Claims

1. A method for preparing nanosheet crystal beam films using a one-pot incubation method, comprising the following steps: (1) Preparation of the base solution: The spin-coatable polymer is added to a solvent and stirred to dissolve, thus preparing a polymer base solution; the spin-coatable polymer includes one of polyamide, polyvinylidene fluoride, and polyvinyl alcohol, and the solvent is one of formic acid, N,N-dimethylformamide, and water; the concentration of the base solution is 12-16 wt%. (2) Spin-coating polymer substrate: The polymer substrate solution is dropped onto the substrate and spin-coated using a spin coater. The substrate is then dried to obtain the polymer substrate. The spin-coating process using a spin coater involves using a disposable dropper to draw the substrate solution and drop it onto the substrate. The spin-coating time is 10-100 s, the spin-coating speed is 200 rpm-2000 rpm, and the acceleration is 100-1000 rpm / s. (3) Preparation of incubation solution: The semi-crystalline polymer is added to the incubation solvent and heated to dissolve, thereby obtaining the incubation solution; the semi-crystalline polymer is polyamide, and the incubation solvent is selected from one of glycerol, 1,4-butanediol, toluene, ethylene glycol, N,N-dimethylformamide, chlorobenzene, glacial acetic acid, water, and xylene; the concentration of the incubation solution is 0.05-0.5 wt%. (4) One-pot incubation: Add the polymer substrate from step (2) to the incubation solution and cool down to induce crystallization; the cooling-induced crystallization means cooling down to 130-150℃ to induce crystallization for 20-40 minutes.

2. The method as described in claim 1, characterized in that, Includes the following steps: (1) Preparation of base solution: Add PA66 to formic acid, stir to dissolve, and obtain a base solution with a concentration of 12-16wt%; (2) Spin-coating polymer substrate: The substrate solution is dropped onto an acrylic plate and spin-coated using a spin coater. The polymer substrate is then dried. (3) Preparation of incubation solution: Add PA66 to ethylene glycol and heat to 160-220℃ to dissolve for 0.5-2h to obtain an incubation solution with a concentration of 0.05-0.5 wt%; (4) One-pot incubation: Add the polymer substrate from step (2) to the incubation solution, cool to 130-150℃ to induce crystallization for 20-40 minutes, and obtain a PA66 spin-coated film containing PA66 flakes.

3. The method as described in claim 2, characterized in that, Step (2) The spin coating speed is 500-1500 rpm, the acceleration is 300-800 rpm / s, and the spin coating time is 30-80 s.

4. The method as described in claim 3, characterized in that, Step (2) The spin coating speed is 1000 rpm, the acceleration is 500 rpm / s, and the spin coating time is 60 s.

5. The method as described in claim 2, characterized in that, Step (3) Incubation solution concentration: 0.12-0.26 wt%.

6. The application of the nanosheet crystal bundle film obtained by the method of any one of claims 1-5 in a triboelectric nanogenerator.

7. The application of the nanosheet crystal bundle film obtained by the method of any one of claims 1-5 in the field of self-powered sensing technology.

Images