An irradiated modified ferroelectric polymer and preparation method thereof

Abstract

The present invention belongs to the technical field of flexible piezoelectric polymer materials, and discloses an irradiated modified ferroelectric polymer and a preparation method thereof. The preparation method includes: dissolving a poly(vinylidene fluoride-trifluoroethylene) polymer with a ferroelectric phase in an organic solvent, heating to form a film, and then annealing in a vacuum environment to form a poly(vinylidene fluoride-trifluoroethylene) polymer film; wherein, the molar content of trifluoroethylene in the poly(vinylidene fluoride-trifluoroethylene) polymer is 35% - 45%; performing particle beam irradiation on the poly(vinylidene fluoride-trifluoroethylene) polymer film, and inducing the formation of a ferroelectric polymer with a morphotropic phase boundary. The present invention utilizes particle beam irradiation to form a morphotropic phase boundary in the poly(vinylidene fluoride-trifluoroethylene) polymer, thereby significantly improving the piezoelectric coefficient of the material.

Description

Technical Field

[0001] The present invention belongs to the technical field related to flexible piezoelectric polymer materials, and more specifically, relates to a radiation-modified ferroelectric polymer and a preparation method thereof. Background Art

[0002] With the rapid development of flexible electronic devices, wearable devices and Internet of Things technologies, piezoelectric materials, as the core carriers for realizing energy conversion and intelligent sensing functions, play an irreplaceable role in modern electronic devices. Especially in the face of the urgent needs of the new generation of electronic devices for lightweight, flexibility and convenience, piezoelectric polymers show unique advantages in the competition with traditional piezoelectric ceramic materials due to their low density, high flexibility and good biocompatibility, and are widely used in fields such as sensors, actuators, energy harvesting devices and biomedical devices.

[0003] Among many piezoelectric polymers, polyvinylidene fluoride (PVDF)-based ferroelectric polymers are a major type of piezoelectric polymers, which have excellent chemical stability, mechanical strength and processability.

[0004] Piezoelectric coefficient d 33 is a coefficient that measures the ability of a piezoelectric material to convert mechanical energy into electrical energy and vice versa, and is also an important parameter that determines the performance of flexible sensor devices. Compared with traditional piezoelectric ceramic materials (such as lead zirconate titanate (PZT) ceramics, d 33 which can reach several hundred pC / N), the relatively low piezoelectric coefficient (about 30 pC / N) of PVDF-based ferroelectric polymers limits their application in some scenarios with high sensitivity requirements. The methods for improving the piezoelectric coefficient of PVDF-based ferroelectric polymers mainly include molecular copolymerization, chemical modification and inorganic nanofiller composite, etc., but these methods have limited improvement on the piezoelectric coefficient. The morphotropic phase boundary (MPB) is a physical concept derived from piezoelectric ceramics. Near the phase boundary, the energy barrier between different phases is lower, and polarization is more likely to rotate under external stimuli, which can effectively improve the piezoelectric performance. However, this method has too strict requirements for the component control in the chemical synthesis process of PVDF-based ferroelectric polymers. In actual industrial production, the ratio of raw materials and the components of the synthesized products cannot be exactly the same, and there is a problem that the components of the products cannot be precisely controlled, resulting in a significant reduction in piezoelectric performance. Summary of the Invention

[0005] Aiming at the above defects or improvement requirements of the prior art, the present invention provides a radiation-modified ferroelectric polymer and a preparation method thereof, aiming to construct a morphotropic phase boundary in the ferroelectric polymer by particle beam irradiation, thereby solving the technical problems such as low piezoelectric coefficient and difficult performance improvement of existing ferroelectric polymers.

[0006] To achieve the above object, according to the first aspect of the present invention, a method for preparing an irradiated modified ferroelectric polymer is provided, including the following steps:

[0007] (1) Dissolve a polyvinylidene fluoride-trifluoroethylene polymer with a ferroelectric phase in an organic solvent, heat to form a film, and then anneal in a vacuum environment to form a polyvinylidene fluoride-trifluoroethylene polymer film; wherein, the molar content of trifluoroethylene in the polyvinylidene fluoride-trifluoroethylene polymer is 35% - 45%;

[0008] (2) Perform particle beam irradiation on the polyvinylidene fluoride-trifluoroethylene polymer film and induce the formation of a ferroelectric polymer with a quasi-homogeneous phase boundary.

[0009] As a preference of the present invention, in step (2), the atmosphere of the particle beam irradiation is air or nitrogen, and the dose is 1 Mrad - 40 Mrad.

[0010] As a preference of the present invention, in step (2), the incident direction of the particle beam is perpendicular to the film surface, and the beam current energy is 1.2 MeV - 20 MeV.

[0011] As a preference of the present invention, in step (2), the particle beam for the particle beam irradiation is a proton beam or an electron beam.

[0012] As a preference of the present invention, in step (1), the organic solvent is selected from one of N,N-dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone.

[0013] As a preference of the present invention, in step (1), the concentration of the polymer solution is 10 mg / mL - 100 mg / mL.

[0014] As a preference of the present invention, in step (1), the thickness of the polyvinylidene fluoride-trifluoroethylene polymer film is 10 - 100 microns.

[0015] As a preference of the present invention, in step (1), the heating to form a film includes: after dissolving a polyvinylidene fluoride-trifluoroethylene polymer with a ferroelectric phase in an organic solvent to form a polymer solution, casting the polymer solution on the surface of a substrate and heating to form a film.

[0016] As a preference of the present invention, in step (1), the annealing conditions are under vacuum conditions, the temperature is 120°C - 130°C, and the time is 8 h - 24 h.

[0017] According to the second aspect of the present invention, an irradiated modified ferroelectric polymer is provided, and the irradiated modified ferroelectric polymer is prepared by using the method for preparing an irradiated modified ferroelectric polymer as described in the first aspect of the present invention.

[0018] Generally speaking, compared with the prior art, the above technical solution conceived by the present invention mainly has the following technical advantages:

[0019] 1. The present invention utilizes particle beam irradiation to construct a morphotropic phase boundary in a ferroelectric polymer film, and after irradiation modification, a polymer film material with a significantly improved piezoelectric coefficient is obtained. This modification method realizes the improvement of the piezoelectric coefficient and other properties of the ferroelectric polymer by selecting the type of polymer in the process and combining the control of the particle beam irradiation dose of the polymer on the basis of the ferroelectric polymer film, without the need for a complex chemical synthesis process, and a ferroelectric polymer film with a specific molecular chain conformation can be prepared.

[0020] 2. Preferably, the incident direction of the particle beam in the present invention is perpendicular to the film surface to ensure uniform incidence of high-energy particles on the film surface.

[0021] 3. The present invention selects a proton beam or an electron beam, which acts on the polymer molecular chain to cause a phase transition and generate a morphotropic phase boundary.

[0022] 4. Preferably, the poly(vinylidene fluoride-trifluoroethylene) polymer with a ferroelectric phase in the present invention is dissolved in an organic solvent. By adjusting the type of organic solvent and the concentration of the polymer solution, the film formation is made uniform; by controlling the film formation thickness, the uniformity of subsequent irradiation is ensured, which is convenient for the preparation of devices in the field of piezoelectric sensing.

[0023] 5. Preferably, the poly(vinylidene fluoride-trifluoroethylene) polymer with a ferroelectric phase in the present invention is annealed after film formation to further volatilize the residual organic solvent and avoid its influence on the piezoelectric properties.

[0024] 6. The irradiated and modified ferroelectric polymer prepared by the present invention has a higher piezoelectric coefficient (up to about 70 pC / N at maximum), and can be applied to high-sensitivity piezoelectric sensing electronic devices, such as intelligent sensors, acoustic devices, wearable devices, and medical health monitoring devices. d 33 It can be applied to high-sensitivity piezoelectric sensing electronic devices, such as intelligent sensors, acoustic devices, wearable devices, and medical health monitoring devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a flowchart of a preparation method of an irradiated and modified ferroelectric polymer according to an example of the present invention.

[0026] Figure 2 It is the X-ray diffraction and infrared spectrum of Examples 3-5 of the present invention and the original polymer (P(VDF-TrFE) 65 / 35 mol%); wherein Figure 2 a in trans is the X-ray diffraction, b is the infrared spectrum at the wave number corresponding to the all-

[0027] Figure 3 It is a comparison chart of the piezoelectric coefficients of Examples 1-5 of the present invention and the original polymer (P(VDF-TrFE) 65 / 35 mol%).

[0028] Figure 4 It is a comparison chart of the piezoelectric coefficients of Examples 6-7 of the present invention and the original polymer (P(VDF-TrFE) 55 / 45 mol%).

[0029] Figure 5 It is a comparison chart of the piezoelectric coefficients between Example 4 and Example 8, Example 6 and Example 9, and Comparative Example 1 and Comparative Example 3 of the present invention. Detailed implementation manners

[0030] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0031] The present invention provides a preparation method of an irradiated modified ferroelectric polymer, which constructs a morphotropic phase boundary in the ferroelectric polymer by means of particle beam irradiation, significantly improves the piezoelectric coefficient of the polymer, and provides a key material for realizing high-sensitivity flexible piezoelectric sensing and other fields.

[0032] Please combine Figure 1 with it, and the preparation process specifically includes the following steps:

[0033] Step 1, dissolve a poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) polymer with a ferroelectric phase in an organic solvent to obtain a poly(vinylidene fluoride-trifluoroethylene) solution; heat and volatilize the solvent of the polymer solution to form a film, and then anneal it by raising the temperature in a vacuum environment to obtain a polymer film.

[0034] Among them, the molar content of trifluoroethylene in the poly(vinylidene fluoride-trifluoroethylene) polymer is 35% to 45%.

[0035] Step 2, perform particle beam irradiation modification on the polymer film, induce the ferroelectric phase of the polymer to undergo an unstable transition to a transition phase between the ferroelectric phase and the relaxor ferroelectric phase, and construct a morphotropic phase boundary to obtain a ferroelectric polymer film material with a high piezoelectric coefficient.

[0036] Among them, the dose of particle beam irradiation is 1 Mrad to 40 Mrad. More preferably, the molar content of trifluoroethylene in the polyvinylidene fluoride-trifluoroethylene polymer is 35%, and the dose of particle beam irradiation is 10 Mrad to 40 Mrad; the molar content of trifluoroethylene in the polyvinylidene fluoride-trifluoroethylene polymer is 45%, and the dose of particle beam irradiation is 1 Mrad to 5 Mrad.

[0037] Preferably, in step two, the atmosphere for particle beam irradiation modification is air or nitrogen.

[0038] Preferably, in step two, the particle beam for irradiation modification is a proton beam or an electron beam, the incident direction of the particle beam is perpendicular to the film surface, and the beam current energy is 1.2 MeV to 20 MeV.

[0039] Preferably, in step one, the organic solvent is any one of N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and N-methylpyrrolidone (NMP); the concentration of the prepared polyvinylidene fluoride-trifluoroethylene solution is 10 mg / mL to 100 mg / mL. For example, the polyvinylidene fluoride-trifluoroethylene polymer is dissolved in an organic solvent and stirred and mixed until a uniform polymer solution is formed. The stirring time used is 8 h to 12 h, and the temperature is 25°C to 70°C.

[0040] Preferably, in step one, the polymer solution is cast on the surface of a smooth substrate and heated to form a film, and then annealed by heating in a vacuum environment until the solvent is completely volatilized to obtain a polymer film. The smooth substrate is any one of glass, quartz, and metal.

[0041] Preferably, in step one, the thickness range of the polymer film is 10 to 100 microns.

[0042] Preferably, in step one, the temperature for drying the solution is 60°C to 80°C.

[0043] Preferably, in step one, the temperature for annealing in a vacuum environment is 120°C to 130°C, and the time is 8 h to 24 h.

[0044] The present invention also provides an irradiated modified high piezoelectric coefficient ferroelectric polymer prepared by using the preparation method of the irradiated modified high piezoelectric coefficient ferroelectric polymer as described above.

[0045] Please refer to Figure 2 、 Figure 3 、 Figure 4 and Table 1, and the following will further elaborate on the present invention with specific examples.

[0046] Example 1: A preparation method of an irradiated modified ferroelectric polymer provided in Example 1 of the present invention mainly includes the following steps:

[0047] 1 g of P(VDF-TrFE) 65 / 35 mol% was added to 20 mL of DMF solution to prepare a polymer solution with a concentration of 50 mg / mL. The solution was stirred at a rate of 400 rpm / min at 40 °C for 12 h. Then, the obtained solution was cast onto a glass plate and volatilized at 80 °C to form a film with a thickness of 30 microns. Subsequently, it was annealed at 130 °C for 12 h in a vacuum environment. Finally, it was irradiated with a proton beam with a beam energy of 20 MeV perpendicular to the film surface. The atmosphere was nitrogen and the dose was 1 Mrad.

[0048] Example 2: A preparation method of an irradiated modified ferroelectric polymer provided in Example 2 of the present invention mainly includes the following steps:

[0049] 1 g of P(VDF-TrFE) 65 / 35 mol% was added to 20 mL of DMF solution to prepare a polymer solution with a concentration of 50 mg / mL. The solution was stirred at a rate of 400 rpm / min at 40 °C for 12 h. Then, the obtained solution was cast onto a glass plate and volatilized at 80 °C to form a film with a thickness of 30 microns. Subsequently, it was annealed at 130 °C for 12 h in a vacuum environment. Finally, it was irradiated with a proton beam with a beam energy of 20 MeV perpendicular to the film surface. The atmosphere was nitrogen and the dose was 10 Mrad.

[0050] Example 3: A preparation method of an irradiated modified ferroelectric polymer provided in Example 3 of the present invention mainly includes the following steps:

[0051] 1 g of P(VDF-TrFE) 65 / 35 mol% was added to 20 mL of DMF solution to prepare a polymer solution with a concentration of 50 mg / mL. The solution was stirred at a rate of 400 rpm / min at 40 °C for 12 h. Then, the obtained solution was cast onto a glass plate and volatilized at 80 °C to form a film with a thickness of 30 microns. Subsequently, it was annealed at 130 °C for 12 h in a vacuum environment. Finally, it was irradiated with a proton beam with a beam energy of 20 MeV perpendicular to the film surface. The atmosphere was nitrogen and the dose was 20 Mrad.

[0052] Example 4: A preparation method of an irradiated modified ferroelectric polymer provided in Example 4 of the present invention mainly includes the following steps:

[0053] 1 g of P(VDF-TrFE) 65 / 35 mol% was added to 20 mL of DMF solution to prepare a polymer solution with a concentration of 50 mg / mL. The solution was stirred at a rate of 400 rpm / min at 40 °C for 12 h. Then, the obtained solution was cast on a glass plate and volatilized at 80 °C to form a film with a thickness of 30 microns. Subsequently, it was annealed at 130 °C for 12 h in a vacuum environment. Finally, it was irradiated with a proton beam with a beam energy of 20 MeV perpendicular to the film surface. The atmosphere was nitrogen and the dose was 30 Mrad.

[0054] Example 5: A preparation method of an irradiated modified ferroelectric polymer provided in Example 5 of the present invention mainly includes the following steps:

[0055] 1 g of P(VDF-TrFE) 65 / 35 mol% was added to 20 mL of DMF solution to prepare a polymer solution with a concentration of 50 mg / mL. The solution was stirred at a rate of 400 rpm / min at 40 °C for 12 h. Then, the obtained solution was cast on a glass plate and volatilized at 80 °C to form a film with a thickness of 30 microns. Subsequently, it was annealed at 130 °C for 12 h in a vacuum environment. Finally, it was irradiated with a proton beam with a beam energy of 20 MeV perpendicular to the film surface. The atmosphere was nitrogen and the dose was 40 Mrad.

[0056] Example 6: A preparation method of an irradiated modified ferroelectric polymer provided in Example 6 of the present invention mainly includes the following steps:

[0057] 1 g of P(VDF-TrFE) 55 / 45 mol% was added to 20 mL of DMF solution to prepare a polymer solution with a concentration of 50 mg / mL. The solution was stirred at a rate of 400 rpm / min at 40 °C for 12 h. Then, the obtained solution was cast on a glass plate and volatilized at 80 °C to form a film with a thickness of 30 microns. Subsequently, it was annealed at 130 °C for 12 h in a vacuum environment. Finally, it was irradiated with a proton beam with a beam energy of 20 MeV perpendicular to the film surface. The atmosphere was nitrogen and the dose was 1 Mrad.

[0058] Example 7: A preparation method of an irradiated modified ferroelectric polymer provided in Example 7 of the present invention mainly includes the following steps:

[0059] 1 g of P(VDF-TrFE) 55 / 45 mol% was added to 20 mL of DMF solution to prepare a polymer solution with a concentration of 50 mg / mL. The solution was stirred at a rate of 400 rpm / min at 40 °C for 12 h. Then, the obtained solution was cast on a glass plate and volatilized at 80 °C to form a film with a thickness of 30 μm. Subsequently, it was annealed at 130 °C for 12 h in a vacuum environment. Finally, it was irradiated with a proton beam with a beam energy of 20 MeV perpendicular to the film surface. The atmosphere was nitrogen and the dose was 5 Mrad.

[0060] Example 8: A preparation method of an irradiated modified ferroelectric polymer provided in Example 8 of the present invention mainly includes the following steps:

[0061] 1 g of P(VDF-TrFE) 65 / 35 mol% was added to 20 mL of DMF solution to prepare a polymer solution with a concentration of 50 mg / mL. The solution was stirred at a rate of 400 rpm / min at 40 °C for 12 h. Then, the obtained solution was cast on a glass plate and volatilized at 80 °C to form a film with a thickness of 30 μm. Subsequently, it was annealed at 130 °C for 12 h in a vacuum environment. Finally, it was irradiated with an electron beam with a beam energy of 1.2 MeV perpendicular to the film surface. The atmosphere was nitrogen and the dose was 30 Mrad.

[0062] Example 9: A preparation method of an irradiated modified ferroelectric polymer provided in Example 9 of the present invention mainly includes the following steps:

[0063] 1 g of P(VDF-TrFE) 55 / 45 mol% was added to 20 mL of DMF solution to prepare a polymer solution with a concentration of 50 mg / mL. The solution was stirred at a rate of 400 rpm / min at 40 °C for 12 h. Then, the obtained solution was cast on a glass plate and volatilized at 80 °C to form a film with a thickness of 30 μm. Subsequently, it was annealed at 130 °C for 12 h in a vacuum environment. Finally, it was irradiated with an electron beam with a beam energy of 1.2 MeV perpendicular to the film surface. The atmosphere was nitrogen and the dose was 1 Mrad.

[0064] Example 10: A preparation method of an irradiated modified ferroelectric polymer provided in Example 10 of the present invention mainly includes the following steps:

[0065] 1 g of P(VDF-TrFE) 65 / 35 mol% was added to 50 mL of DMF solution to prepare a polymer solution with a concentration of 20 mg / mL. The solution was stirred at a rate of 400 rpm / min at 40 °C for 12 h. Then, the obtained solution was cast on a glass plate and volatilized at 80 °C to form a film with a thickness of 10 μm. Subsequently, it was annealed at 130 °C for 12 h in a vacuum environment. Finally, it was irradiated with a proton beam with a beam energy of 20 MeV perpendicular to the film surface. The atmosphere was nitrogen and the dose was 30 Mrad.

[0066] Example 11: A preparation method of an irradiated modified ferroelectric polymer provided in Example 11 of the present invention mainly includes the following steps:

[0067] 1.6 g of P(VDF-TrFE) 65 / 35 mol% was added to 20 mL of DMF solution to prepare a polymer solution with a concentration of 80 mg / mL. The solution was stirred at a rate of 400 rpm / min at 40 °C for 12 h. Then, the obtained solution was cast on a glass plate and volatilized at 80 °C to form a film with a thickness of 100 μm. Subsequently, it was annealed at 130 °C for 12 h in a vacuum environment. Finally, it was irradiated with a proton beam with a beam energy of 20 MeV perpendicular to the film surface. The atmosphere was nitrogen and the dose was 30 Mrad.

[0068] Comparative Example 1: A preparation method of an irradiated modified ferroelectric polymer provided in Comparative Example 1 of the present invention mainly includes the following steps:

[0069] 1 g of P(VDF-TrFE) 65 / 35 mol% was added to 20 mL of DMF solution to prepare a polymer solution with a concentration of 50 mg / mL. The solution was stirred at a rate of 400 rpm / min at 40 °C for 12 h. Then, the obtained solution was cast on a glass plate and volatilized at 80 °C to form a film with a thickness of 30 μm. Subsequently, it was annealed at 130 °C for 12 h in a vacuum environment. Finally, it was irradiated with a proton beam with a beam energy of 20 MeV perpendicular to the film surface. The atmosphere was nitrogen and the dose was 50 Mrad.

[0070] Comparative Example 2: A preparation method of an irradiated modified ferroelectric polymer provided in Comparative Example 2 of the present invention mainly includes the following steps:

[0071] 1 g of P(VDF-TrFE) 55 / 45 mol% was added to 20 mL of DMF solution to prepare a polymer solution with a concentration of 50 mg / mL. It was stirred at a rate of 400 rpm / min at 40 °C for 12 h. Then the obtained solution was cast on a glass plate and volatilized at 80 °C to form a film with a thickness of 30 microns. Subsequently, it was annealed at 130 °C for 12 h in a vacuum environment. Finally, it was irradiated perpendicularly to the film surface with a proton beam having a beam energy of 20 MeV. The atmosphere was nitrogen and the dose was 50 Mrad.

[0072] Comparative Example 3: A preparation method of an irradiated modified ferroelectric polymer provided in Comparative Example 3 of the present invention mainly includes the following steps:

[0073] 1 g of P(VDF-TrFE) 65 / 35 mol% was added to 20 mL of DMF solution to prepare a polymer solution with a concentration of 50 mg / mL. It was stirred at a rate of 400 rpm / min at 40 °C for 12 h. Then the obtained solution was cast on a glass plate and volatilized at 80 °C to form a film with a thickness of 30 microns. Subsequently, it was annealed at 130 °C for 12 h in a vacuum environment. Finally, it was irradiated perpendicularly to the film surface with an electron beam having a beam energy of 1.2 MeV. The atmosphere was nitrogen and the dose was 50 Mrad.

[0074] Comparative Example 4: A preparation method of an irradiated modified ferroelectric polymer provided in Comparative Example 4 of the present invention mainly includes the following steps:

[0075] 1 g of P(VDF-TrFE) 80 / 20 mol% was added to 20 mL of DMF solution to prepare a polymer solution with a concentration of 50 mg / mL. It was stirred at a rate of 400 rpm / min at 40 °C for 12 h. Then the obtained solution was cast on a glass plate and volatilized at 80 °C to form a film with a thickness of 30 microns. Subsequently, it was annealed at 130 °C for 12 h in a vacuum environment. Finally, it was irradiated perpendicularly to the film surface with a proton beam having a beam energy of 20 MeV. The atmosphere was nitrogen and the dose was 40 Mrad.

[0076] Comparative Example 5: A preparation method of an irradiated modified ferroelectric polymer provided in Comparative Example 5 of the present invention mainly includes the following steps:

[0077] 2 g of P(VDF-TrFE) 65 / 35 mol% was added to 20 mL of DMF solution to prepare a polymer solution with a concentration of 100 mg / mL. The solution was stirred at a rate of 400 rpm / min at 40 °C for 12 h. Then, the obtained solution was cast on a glass plate and volatilized at 80 °C to form a film with a thickness of 120 microns. The film was annealed at 130 °C for 12 h in a vacuum environment. Subsequently, the film was folded in half, heated above the melting point, and pressed flat under pressure to obtain a film with a thickness of 200 microns. Finally, the film was irradiated perpendicularly to the film surface with a proton beam having a beam energy of 20 MeV in a nitrogen atmosphere with a dose of 30 Mrad.

[0078] In the specific embodiments of the present invention, the commercial PVDF used as the film material was purchased from PolyK; P(VDF-TrFE) 80 / 20 mol%, P(VDF-TrFE) 65 / 35 mol%, and P(VDF-TrFE) 55 / 45 mol% were all powders and were purchased from Arkema. The following examples were used to modify the above different raw materials, and the raw materials and the polymer materials prepared by modification were subjected to performance characterization and piezoelectric performance testing.

[0079] The structural characterization tests of the present invention were X-ray diffraction and infrared spectroscopy, and the infrared spectroscopy tests were measured by a spectrometer in ATR mode. The piezoelectric performance tests of the present invention were carried out using a d 33 quasi-static tester. Specifically, each of the original and modified polymers was measured under the condition of applying a static force of 1 N with a dynamic force of 0.25 N at a frequency of 110 Hz.

[0080] Figure 2 Shown are the X-ray diffraction and infrared spectroscopy of Examples 2-4 and the original polymer (P(VDF-TrFE) 65 / 35 mol%). Figure 2 It shows that after irradiation, a quasi-homogeneous phase boundary was generated in the original P(VDF-TrFE) 65 / 35 mol% polymer. Specifically, as Figure 2 shown in a, the peak of the all- trans conformation near 19.6 ° gradually weakened after irradiation, and a peak of the 3 / 1 helix conformation appeared near 19 °; as Figure 2 shown in b and c, the peak of the all- -1 conformation at 1286 cm trans gradually weakened, and the peak of the 3 / 1 helix conformation at 506 cm -1 gradually increased. Therefore, during the transformation from the all- trans conformation to the 3 / 1 helix conformation, a mixed state of two-phase coexistence was generated, indicating the generation of a quasi-homogeneous phase boundary.

[0081] Figures 3 - 5 They are all the piezoelectric performance test data of the polymers corresponding to the above embodiments or raw materials.

[0082] Table 1 shows the comparison of raw material selection, irradiation parameters, and measured piezoelectric coefficients of the examples, comparative examples, raw polymers, and commercial piezoelectric polymers.

[0083] Table 1: Raw material selection, irradiation parameters, and measured piezoelectric coefficients of the examples, comparative examples, raw polymers, and commercial piezoelectric polymers;

[0084] ;

[0085] Figure 3 , Figure 4 It shows that the piezoelectric coefficients of Examples 1 - 7 are all improved. Combining Comparative Examples 1 - 2 and Comparative Example 4, the range of the irradiation dose is determined to be 1 Mrad - 40 Mrad, and the molar content of trifluoroethylene in the polyvinylidene fluoride - trifluoroethylene polymer is 35% - 45%.

[0086] Figure 5 It shows that by comparing Example 4 with Example 8, Example 6 with Example 9, and Comparative Example 1 with Comparative Example 3, it shows that the effects of the particle beam being a proton beam or an electron beam are similar, and both can be selected as the corresponding particles for use.

[0087] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the present invention and its equivalent technologies, the present invention also intends to include these changes and modifications. The above - described embodiments are only preferred embodiments given to fully illustrate the present invention, and the scope of protection is not limited thereto. Equivalent substitutions or transformations made by those skilled in the art on the basis of the present invention are all within the scope of protection of the present invention.

Claims

1. A method for preparing a ferroelectric polymer with a morphotropic phase boundary by irradiation modification, characterized in that, It includes the following steps: (1) Dissolve the poly(vinylidene fluoride-trifluoroethylene) polymer with a ferroelectric phase in an organic solvent, heat it to form a film, and then anneal it in a vacuum environment to form a poly(vinylidene fluoride-trifluoroethylene) polymer film; wherein, the molar content of trifluoroethylene in the poly(vinylidene fluoride-trifluoroethylene) polymer is 35% - 45%; the thickness of the poly(vinylidene fluoride-trifluoroethylene) polymer film is 10 - 100 microns; (2) Perform particle beam irradiation on the poly(vinylidene fluoride-trifluoroethylene) polymer film and induce the formation of a ferroelectric polymer with a quasi-homogeneous phase boundary; the incident direction of the particle beam is perpendicular to the film surface, and the beam energy is 1.2 MeV - 20 MeV; the dose of the particle beam irradiation is 1 Mrad - 40 Mrad.

2. The method for preparing a ferroelectric polymer with a morphotropic phase boundary by irradiation modification as claimed in claim 1, wherein In step (2), the atmosphere of the particle beam irradiation is air or nitrogen.

3. The method for preparing a ferroelectric polymer with a morphotropic phase boundary by irradiation modification according to claim 1, characterized in that, In step (2), the particle beam of the particle beam irradiation is a proton beam or an electron beam.

4. The method for preparing a ferroelectric polymer with a morphotropic phase boundary by irradiation modification as claimed in claim 1, wherein, In step (1), the organic solvent is selected from one of N,N-dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone.

5. The method for preparing a ferroelectric polymer with a morphotropic phase boundary by irradiation modification as claimed in claim 1, wherein In step (1), the concentration of the polymer solution is 10 mg / mL - 100 mg / mL.

6. The method for preparing a ferroelectric polymer with a morphotropic phase boundary by irradiation modification as claimed in claim 1, wherein In step (1), the heating to form a film includes: after dissolving the poly(vinylidene fluoride-trifluoroethylene) polymer with a ferroelectric phase in an organic solvent to form a polymer solution, casting the polymer solution on the surface of a substrate and heating it to form a film.

7. The method for preparing a ferroelectric polymer with a morphotropic phase boundary by irradiation modification according to claim 1, characterized in that In step (1), the conditions for annealing are under vacuum conditions, the temperature is 120°C - 130°C, and the time is 8 h - 24 h.

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