Irradiation modified ferroelectric polymer and preparation method thereof

Abstract

The invention belongs to the technical field of flexible piezoelectric polymer materials, and discloses an irradiation modified ferroelectric polymer and a preparation method thereof. The preparation method comprises the following steps: dissolving a polyvinylidene fluoride-trifluoroethylene polymer with a ferroelectric phase in an organic solvent, heating to form a film, and annealing 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 percent to 45 percent; and carrying out particle beam irradiation on the polyvinylidene fluoride-trifluoroethylene polymer film, and inducing to form a ferroelectric polymer with a morphotropic phase boundary. According to the preparation method, a morphotropic phase boundary is formed in the polyvinylidene fluoride-trifluoroethylene polymer by utilizing particle beam irradiation, so that the piezoelectric coefficient of the material is remarkably improved.

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 technology, piezoelectric materials, as the core carrier for realizing energy conversion and intelligent sensing functions, play an irreplaceable role in modern electronic devices. In particular, in the face of the urgent need for lightweight, flexible and convenient new generation electronic devices, piezoelectric polymers, with their low density, high flexibility and good biocompatibility, have shown unique advantages in the competition with traditional piezoelectric ceramic materials and are widely used in sensors, actuators, energy harvesting devices and biomedical equipment.

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

[0004] Piezoelectric coefficient d 33 It is a coefficient that measures the mutual conversion ability between mechanical energy and electrical energy of piezoelectric materials, 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 Compared with PVDF-based ferroelectric polymers (which can reach several hundred pC / N), the lower piezoelectric coefficient (about 30 pC / N) of PVDF-based ferroelectric polymers limits their application in some scenarios with high sensitivity requirements. The main methods to improve the piezoelectric coefficient of PVDF-based ferroelectric polymers include molecular copolymerization, chemical modification and inorganic nanofiller composites, but these methods have limited improvement on the piezoelectric coefficient. The quasi-modular phase boundary (MPB) is a physical concept derived from piezoelectric ceramics. Near the phase boundary, the energy barrier between different phases is lower, and the polarization is more likely to rotate under external stimulation, which can effectively improve the piezoelectric performance. However, this method places too strict requirements on the component control of PVDF-based ferroelectric polymers during the chemical synthesis process. In actual industrial production, the proportion of raw materials and the composition of the synthetic product cannot be completely consistent. There is a problem that the product composition cannot be accurately controlled, resulting in a significant reduction in piezoelectric performance. Summary of the invention

[0005] In view of the above defects or improvement needs of the prior art, the present invention provides a radiation-modified ferroelectric polymer and a preparation method, which aims to construct a quasi-modular phase boundary in the ferroelectric polymer by particle beam irradiation, thereby solving the technical problems of low piezoelectric coefficient and difficulty in improving performance of existing ferroelectric polymers.

[0006] To achieve the above object, according to a first aspect of the present invention, a method for preparing a radiation-modified ferroelectric polymer is provided, comprising the following steps: (1) dissolving a polyvinylidene fluoride-trifluoroethylene polymer having a ferroelectric phase in an organic solvent, heating to form a film, and then annealing 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% to 45%; (2) The polyvinylidene fluoride-trifluoroethylene polymer film is irradiated with a particle beam to induce the formation of a ferroelectric polymer with a quasi-morphic phase boundary.

[0007] As a preferred embodiment of the present invention, in step (2), the atmosphere of the particle beam irradiation is air or nitrogen, and the dosage is 1 Mrad to 40 Mrad.

[0008] As a preferred embodiment of the present invention, in step (2), the incident direction of the particle beam is perpendicular to the surface of the film, and the beam energy is 1.2 MeV~20 MeV.

[0009] As a preferred embodiment of the present invention, in step (2), in step (2), the particle beam of the particle beam irradiation is a proton beam or an electron beam.

[0010] As a preferred embodiment of the present invention, in step (1), the organic solvent is selected from one of N,N-dimethylformamide, dimethyl sulfoxide and N-methylpyrrolidone.

[0011] As a preferred embodiment of the present invention, in step (1), the concentration of the polymer solution is 10 mg / mL to 100 mg / mL.

[0012] As a preferred embodiment of the present invention, in step (1), the thickness of the polyvinylidene fluoride-trifluoroethylene polymer film is 10 to 100 microns.

[0013] As a preferred embodiment of the present invention, in step (1), the heating film forming comprises: dissolving the polyvinylidene fluoride-trifluoroethylene polymer having a ferroelectric phase in an organic solvent to form a polymer solution, casting the polymer solution on the surface of the substrate, and heating to form a film.

[0014] As a preferred embodiment of the present invention, in step (1), the annealing condition is under vacuum conditions, the temperature is 120°C to 130°C, and the time is 8 h to 24 h.

[0015] According to a second aspect of the present invention, a radiation-modified ferroelectric polymer is provided. The radiation-modified ferroelectric polymer is prepared by the method for preparing the radiation-modified ferroelectric polymer according to the first aspect of the present invention.

[0016] In general, the above technical solution conceived by the present invention has the following technical advantages compared with the prior art: 1. The present invention uses particle beam irradiation to construct a quasi-modular phase boundary in a ferroelectric polymer film, and obtains a polymer film material with a significantly improved piezoelectric coefficient after irradiation modification. The modification method selects the type of polymer in the process, combines the control of the particle beam irradiation dose of the polymer on the basis of the ferroelectric polymer film, and can produce a ferroelectric polymer film with a specific molecular chain conformation without a complex chemical synthesis process, thereby achieving the improvement of the piezoelectric coefficient and other properties of the ferroelectric polymer.

[0017] 2. Preferably, the incident direction of the particle beam in the present invention is perpendicular to the film surface to ensure that high-energy particles are uniformly incident on the film surface.

[0018] 3. The present invention selects a proton beam or an electron beam to act on the polymer molecular chain, causing it to undergo a phase transition and produce a quasi-isotropic phase boundary.

[0019] 4. Preferably, the present invention dissolves the polyvinylidene fluoride-trifluoroethylene polymer having a ferroelectric phase in an organic solvent, and adjusts the type of organic solvent and the concentration of the polymer solution to make the film uniform; by controlling the film thickness, the uniformity of subsequent irradiation is ensured, which facilitates the preparation of devices in the field of piezoelectric sensing.

[0020] 5. Preferably, the polyvinylidene fluoride-trifluoroethylene polymer with a ferroelectric phase in the present invention is annealed after film formation to further volatilize the residual organic solvent to avoid its influence on the piezoelectric properties.

[0021] 6. The irradiation-modified ferroelectric polymer prepared by the present invention has a higher piezoelectric coefficient (maximum d 33 Reaching about 70pC / N), it can be applied to high-sensitivity piezoelectric sensing electronic devices, such as smart sensors, acoustic devices, wearable devices and medical health monitoring equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The present invention is a flowchart of a method for preparing a radiation-modified ferroelectric polymer according to an example of the present invention.

[0023] Figure 2 The X-ray diffraction and infrared spectra of Examples 3-5 and the original polymer (P(VDF-TrFE) 65 / 35 mol%) of the present invention are shown in FIG. Figure 2 a stands for X-ray diffraction and b stands for all- trans The infrared spectrum at the wavenumber corresponding to the conformation, and the infrared spectrum at the wavenumber corresponding to the c 3 / 1 helix conformation.

[0024] Figure 34 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%).

[0025] 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%).

[0026] 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 DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with 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 intended 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.

[0028] The present invention provides a method for preparing an irradiation-modified ferroelectric polymer, which utilizes particle beam irradiation to construct a quasi-modular phase boundary in a ferroelectric polymer, significantly improving the piezoelectric coefficient of the polymer, and providing key materials for realizing fields such as high-sensitivity flexible piezoelectric sensing.

[0029] Please combine Figure 1 , the preparation process specifically includes the following steps: Step 1: dissolving a polyvinylidene fluoride-trifluoroethylene (P(VDF-TrFE)) polymer having a ferroelectric phase in an organic solvent to obtain a polyvinylidene fluoride-trifluoroethylene solution; heating the polymer solution to volatilize the solvent to form a film, and then heating and annealing in a vacuum environment to obtain a polymer film.

[0030] Among them, the molar content of trifluoroethylene in the polyvinylidene fluoride-trifluoroethylene polymer is 35%~45%.

[0031] Step 2: Modify the polymer film by particle beam irradiation to induce the instability of the ferroelectric phase of the polymer to transform into a transition phase between the ferroelectric phase and the relaxor ferroelectric phase, construct a quasi-isotropic phase boundary, and obtain a ferroelectric polymer film material with a high piezoelectric coefficient.

[0032] The particle beam irradiation dose is 1 Mrad to 40 Mrad. More preferably, the molar content of trifluoroethylene in the polyvinylidene fluoride-trifluoroethylene polymer is 35%, and the particle beam irradiation dose is 10 Mrad to 40 Mrad; the molar content of trifluoroethylene in the polyvinylidene fluoride-trifluoroethylene polymer is 45%, and the particle beam irradiation dose is 1 Mrad to 5 Mrad.

[0033] Preferably, in step 2, the atmosphere for particle beam irradiation modification is air or nitrogen.

[0034] Preferably, in step 2, 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 energy is 1.2 MeV to 20 MeV.

[0035] Preferably, in step 1, the organic solvent is any one of N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and N-methylpyrrolidone (NMP); the concentration of the obtained 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 to form a uniform polymer solution, the stirring time used is 8 h to 12 h, and the temperature is 25°C to 70°C.

[0036] Preferably, in step 1, the polymer solution is cast on the surface of a smooth substrate and heated to form a film, and then the polymer film is obtained by heating and annealing in a vacuum environment until the solvent is completely volatilized. The smooth substrate is any one of glass, quartz and metal.

[0037] Preferably, in step 1, the thickness of the polymer film ranges from 10 to 100 microns.

[0038] Preferably, in step 1, the temperature for drying the solution is 60°C to 80°C.

[0039] Preferably, in step 1, the annealing temperature in a vacuum environment is 120° C. to 130° C., and the annealing time is 8 h to 24 h.

[0040] The present invention also provides a radiation-modified high-voltage ferroelectric polymer prepared by the above-mentioned method for preparing the radiation-modified high-voltage ferroelectric polymer.

[0041] See also Figure 2 , Figure 3 , Figure 4 And Table 1, the present invention is further described in detail below with specific examples.

[0042] Embodiment 1: The preparation method of a radiation-modified ferroelectric polymer provided in Embodiment 1 of the present invention mainly comprises the following steps: 1 g P(VDF-TrFE) 65 / 35 mol% was added to 20 mL DMF solution to prepare a polymer solution with a concentration of 50 mg / mL. The solution was stirred at 400 rpm / min at 40°C for 12 h, and then cast on a glass plate. It was evaporated at 80°C to form a film with a thickness of 30 μm, and then annealed at 130°C for 12 h in a vacuum environment. Finally, a proton beam with a beam energy of 20 MeV was used to irradiate the film perpendicular to the surface. The atmosphere was nitrogen and the dose was 1 Mrad.

[0043] Embodiment 2: The preparation method of a radiation-modified ferroelectric polymer provided in Embodiment 2 of the present invention mainly comprises the following steps: 1 g P(VDF-TrFE) 65 / 35 mol% was added to 20 mL DMF solution to prepare a polymer solution with a concentration of 50 mg / mL. The solution was stirred at 400 rpm / min at 40°C for 12 h, and then cast on a glass plate and evaporated at 80°C to form a film with a thickness of 30 μm. It was then annealed at 130°C for 12 h in a vacuum environment, and finally irradiated perpendicularly to the membrane surface with a proton beam with a beam energy of 20 MeV. The atmosphere was nitrogen and the dose was 10 Mrad.

[0044] Embodiment 3: The preparation method of a radiation-modified ferroelectric polymer provided in Embodiment 3 of the present invention mainly comprises the following steps: 1 g P(VDF-TrFE) 65 / 35 mol% was added to 20 mL DMF solution to prepare a polymer solution with a concentration of 50 mg / mL. The solution was stirred at 400 rpm / min at 40°C for 12 h, and then cast on a glass plate and evaporated at 80°C to form a film with a thickness of 30 μm. It was then annealed at 130°C for 12 h in a vacuum environment, and finally irradiated perpendicularly to the membrane surface with a proton beam with a beam energy of 20 MeV. The atmosphere was nitrogen and the dose was 20 Mrad.

[0045] Embodiment 4: The preparation method of a radiation-modified ferroelectric polymer provided in Embodiment 4 of the present invention mainly comprises the following steps: 1 g P(VDF-TrFE) 65 / 35 mol% was added to 20 mL DMF solution to prepare a polymer solution with a concentration of 50 mg / mL. The solution was stirred at 400 rpm / min at 40°C for 12 h, and then cast on a glass plate and evaporated at 80°C to form a film with a thickness of 30 μm. It was then annealed at 130°C for 12 h in a vacuum environment, and finally irradiated perpendicularly to the membrane surface with a proton beam with a beam energy of 20 MeV. The atmosphere was nitrogen and the dose was 30 Mrad.

[0046] Embodiment 5: The preparation method of a radiation-modified ferroelectric polymer provided in Embodiment 5 of the present invention mainly comprises the following steps: 1 g P(VDF-TrFE) 65 / 35 mol% was added to 20 mL DMF solution to prepare a polymer solution with a concentration of 50 mg / mL. The solution was stirred at 400 rpm / min at 40°C for 12 h, and then cast on a glass plate and evaporated at 80°C to form a film with a thickness of 30 μm. It was then annealed at 130°C for 12 h in a vacuum environment, and finally irradiated perpendicularly to the membrane surface with a proton beam with a beam energy of 20 MeV. The atmosphere was nitrogen and the dose was 40 Mrad.

[0047] Embodiment 6: The preparation method of a radiation-modified ferroelectric polymer provided in Embodiment 6 of the present invention mainly comprises the following steps: 1 g P(VDF-TrFE) 55 / 45 mol% was added to 20 mL DMF solution to prepare a polymer solution with a concentration of 50 mg / mL. The solution was stirred at 400 rpm / min at 40°C for 12 h, and then cast on a glass plate. It was evaporated at 80°C to form a film with a thickness of 30 μm, and then annealed at 130°C for 12 h in a vacuum environment. Finally, a proton beam with a beam energy of 20 MeV was used to irradiate the film perpendicular to the surface. The atmosphere was nitrogen and the dose was 1 Mrad.

[0048] Embodiment 7: The preparation method of a radiation-modified ferroelectric polymer provided in Embodiment 7 of the present invention mainly comprises the following steps: 1 g P(VDF-TrFE) 55 / 45 mol% was added to 20 mL DMF solution to prepare a polymer solution with a concentration of 50 mg / mL. The solution was stirred at 400 rpm / min at 40°C for 12 h, and then cast on a glass plate. It was evaporated at 80°C to form a film with a thickness of 30 μm, and then annealed at 130°C for 12 h in a vacuum environment. Finally, a proton beam with a beam energy of 20 MeV was used to irradiate the film perpendicular to the surface. The atmosphere was nitrogen and the dose was 5 Mrad.

[0049] Embodiment 8: The preparation method of a radiation-modified ferroelectric polymer provided in Embodiment 8 of the present invention mainly comprises the following steps: 1 g P(VDF-TrFE) 65 / 35 mol% was added to 20 mL DMF solution to prepare a polymer solution with a concentration of 50 mg / mL. The solution was stirred at 400 rpm / min at 40°C for 12 h, and then cast on a glass plate and evaporated at 80°C to form a film with a thickness of 30 μm. It was then annealed at 130°C for 12 h in a vacuum environment, and finally irradiated perpendicularly to the film surface with an electron beam with a beam energy of 1.2 MeV in a nitrogen atmosphere with a dose of 30 Mrad.

[0050] Embodiment 9: The preparation method of a radiation-modified ferroelectric polymer provided in Embodiment 9 of the present invention mainly comprises the following steps: 1 g P(VDF-TrFE) 55 / 45 mol% was added to 20 mL DMF solution to prepare a polymer solution with a concentration of 50 mg / mL. The solution was stirred at 400 rpm / min at 40°C for 12 h, and then cast on a glass plate. It was evaporated at 80°C to form a film with a thickness of 30 μm, and then annealed at 130°C for 12 h in a vacuum environment. Finally, an electron beam with a beam energy of 1.2 MeV was used to irradiate the film perpendicular to the surface. The atmosphere was nitrogen and the dose was 1 Mrad.

[0051] Embodiment 10: The preparation method of a radiation-modified ferroelectric polymer provided in Embodiment 10 of the present invention mainly comprises the following steps: 1 g P(VDF-TrFE) 65 / 35 mol% was added to 50 mL DMF solution to prepare a polymer solution with a concentration of 20 mg / mL. The solution was stirred at 400 rpm / min at 40°C for 12 h. The obtained solution was then cast on a glass plate and evaporated at 80°C to form a film with a thickness of 10 μm. It was then annealed at 130°C for 12 h in a vacuum environment. Finally, a proton beam with a beam energy of 20 MeV was used to irradiate the film perpendicular to the surface. The atmosphere was nitrogen and the dose was 30 Mrad.

[0052] Embodiment 11: The preparation method of a radiation-modified ferroelectric polymer provided in Embodiment 11 of the present invention mainly comprises the following steps: 1.6 g P(VDF-TrFE) 65 / 35 mol% was added to 20 mL DMF solution to prepare a polymer solution with a concentration of 80 mg / mL. The solution was stirred at 400 rpm / min at 40°C for 12 h, and then cast on a glass plate and evaporated at 80°C to form a film with a thickness of 100 μm. It was then annealed at 130°C for 12 h in a vacuum environment, and finally irradiated perpendicularly to the membrane surface with a proton beam with a beam energy of 20 MeV. The atmosphere was nitrogen and the dose was 30 Mrad.

[0053] Comparative Example 1: The preparation method of a radiation-modified ferroelectric polymer provided in Comparative Example 1 of the present invention mainly comprises the following steps: 1 g P(VDF-TrFE) 65 / 35 mol% was added to 20 mL DMF solution to prepare a polymer solution with a concentration of 50 mg / mL. The solution was stirred at 400 rpm / min at 40°C for 12 h, and then cast on a glass plate and evaporated at 80°C to form a film with a thickness of 30 μm. It was then annealed at 130°C for 12 h in a vacuum environment, and finally irradiated perpendicularly to the membrane surface with a proton beam with a beam energy of 20 MeV. The atmosphere was nitrogen and the dose was 50 Mrad.

[0054] Comparative Example 2: The preparation method of a radiation-modified ferroelectric polymer provided in Comparative Example 2 of the present invention mainly comprises the following steps: 1 g P(VDF-TrFE) 55 / 45 mol% was added to 20 mL DMF solution to prepare a polymer solution with a concentration of 50 mg / mL. The solution was stirred at 400 rpm / min at 40°C for 12 h, and then cast on a glass plate and evaporated at 80°C to form a film with a thickness of 30 μm. It was then annealed at 130°C for 12 h in a vacuum environment, and finally irradiated perpendicularly to the membrane surface with a proton beam with a beam energy of 20 MeV. The atmosphere was nitrogen and the dose was 50 Mrad.

[0055] Comparative Example 3: The preparation method of a radiation-modified ferroelectric polymer provided in Comparative Example 3 of the present invention mainly comprises the following steps: 1 g P(VDF-TrFE) 65 / 35 mol% was added to 20 mL DMF solution to prepare a polymer solution with a concentration of 50 mg / mL. The solution was stirred at 400 rpm / min at 40°C for 12 h. The obtained solution was then cast on a glass plate and evaporated at 80°C to form a film with a thickness of 30 μm. It was then annealed at 130°C for 12 h in a vacuum environment. Finally, an electron beam with a beam energy of 1.2 MeV was used to irradiate the film perpendicular to the surface. The atmosphere was nitrogen and the dose was 50 Mrad.

[0056] Comparative Example 4: The preparation method of a radiation-modified ferroelectric polymer provided in Comparative Example 4 of the present invention mainly comprises the following steps: 1 g P(VDF-TrFE) 80 / 20 mol% was added to 20 mL DMF solution to prepare a polymer solution with a concentration of 50 mg / mL. The solution was stirred at 400 rpm / min at 40°C for 12 h, and then cast on a glass plate and evaporated at 80°C to form a film with a thickness of 30 μm. It was then annealed at 130°C for 12 h in a vacuum environment, and finally irradiated perpendicularly to the membrane surface with a proton beam with a beam energy of 20 MeV. The atmosphere was nitrogen and the dose was 40 Mrad.

[0057] Comparative Example 5: The preparation method of a radiation-modified ferroelectric polymer provided in Comparative Example 5 of the present invention mainly comprises the following steps: 2 g P(VDF-TrFE) 65 / 35 mol% was added to 20 mL DMF solution to prepare a polymer solution with a concentration of 100 mg / mL. The solution was stirred at 400 rpm / min at 40°C for 12 h, and then the obtained solution was cast on a glass plate and evaporated at 80°C to form a film with a thickness of 120 μm. The film was annealed at 130°C in a vacuum environment for 12 h, and then the film was folded in half, heated to above the melting point and pressed flat to obtain a film with a thickness of 200 μm. Finally, a proton beam with a beam energy of 20 MeV was used to irradiate the film perpendicular to the surface. The atmosphere was nitrogen and the dose was 30 Mrad.

[0058] The commercial PVDF used in the specific embodiments of the present invention is a membrane material purchased from PolyK; P(VDF-TrFE) 80 / 20 mol%, P(VDF-TrFE) 65 / 35 mol%, and P(VDF-TrFE) 55 / 45 mol% are all powders purchased from Arkema. The above-mentioned different raw materials are modified by the following examples, and the raw materials and the modified polymer materials are subjected to performance characterization and piezoelectric performance testing.

[0059] The structural characterization tests of the present invention are X-ray diffraction and infrared spectroscopy, wherein the infrared spectroscopy test is measured by a spectrometer in ATR mode. The piezoelectric performance test of the present invention adopts quasi-static d 33 The tester, specifically each original and modified polymer, was measured under the condition of applying a static force of 1 N and a dynamic force of 0.25 N at a frequency of 110 Hz.

[0060] Figure 2 Shown are X-ray diffraction and infrared spectra of Examples 2-4 and the original polymer (P(VDF-TrFE) 65 / 35 mol%). Figure 2 It is shown that after irradiation, a quasi-isotropic phase boundary is generated in the original P(VDF-TrFE) 65 / 35 mol% polymer. Specifically, Figure 2 Middle a shows that after irradiation, all- trans The peak of the conformation gradually weakened, and the peak of the 3 / 1 helix conformation appeared near 19°; Figure 2 b and c show 1286 cm -1 All- trans The peak of the conformation gradually weakened, 506 cm -1 The peak of the 3 / 1 helix conformation gradually increases. trans During the conformational transition to the 3 / 1 helix conformation, a mixed state of two phases coexisted was produced, indicating the generation of a quasi-isotropic phase boundary.

[0061] Figure 3-Figure 5 All of them are the piezoelectric performance test data of the polymers corresponding to the above embodiments or raw materials.

[0062] Table 1 is a comparison of the raw material selection, irradiation parameters and measured piezoelectric coefficients of the embodiments and comparative examples, original polymers and commercial piezoelectric polymers.

[0063] Table 1: Raw material selection, irradiation parameters and measured piezoelectric coefficients of examples and comparative examples, original polymers and commercial piezoelectric polymers; ; Figure 3 , Figure 4 It shows that the piezoelectric coefficients of Examples 1-7 are all improved. Combined with Comparative Examples 1-2 and Comparative Example 4, it is determined that the range of irradiation dose is 1 Mrad~40 Mrad, and the molar content of trifluoroethylene in the polyvinylidene fluoride-trifluoroethylene polymer is 35%~45%.

[0064] Figure 5 It is shown that the comparison between Example 4 and Example 8, Example 6 and Example 9, and Comparative Example 1 and Comparative Example 3 shows that the particle beam has similar effects when it is a proton beam or an electron beam, and both can be selected as corresponding particles for use.

[0065] 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 is also intended to include these changes and variations. The above-described embodiments are only preferred embodiments for fully illustrating the present invention, and their protection scope is not limited thereto. Equivalent substitutions or changes made by those skilled in the art based on the present invention are all within the protection scope of the present invention.

Claims

1. A method for preparing a ferroelectric polymer having a quasi-morphic phase boundary by irradiation modification, characterized in that: The following steps are involved: (1) dissolving a polyvinylidene fluoride-trifluoroethylene polymer having a ferroelectric phase in an organic solvent, heating to form a film, and then annealing 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% to 45%; (2) The polyvinylidene fluoride-trifluoroethylene polymer film is irradiated with a particle beam to induce the formation of a ferroelectric polymer with a quasi-morphic phase boundary.

2. The method for preparing a ferroelectric polymer having a morphotropic phase boundary by irradiation modification according to claim 1, characterized in that: In step (2), the atmosphere of the particle beam irradiation is air or nitrogen, and the dose is 1 Mrad to 40 Mrad.

3. The method for preparing a ferroelectric polymer having a morphotropic phase boundary by irradiation modification according to claim 1, characterized in that: In step (2), the particle beam is incident in a direction perpendicular to the film surface, and the beam energy is 1.2 MeV to 20 MeV.

4. The method for preparing a ferroelectric polymer having 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.

5. The method for preparing a ferroelectric polymer having a morphotropic phase boundary by irradiation modification according to claim 1, characterized in that: In step (1), the organic solvent is selected from one of N,N-dimethylformamide, dimethyl sulfoxide and N-methylpyrrolidone.

6. The method for preparing a ferroelectric polymer having a morphotropic phase boundary by irradiation modification according to claim 1, characterized in that: In step (1), the concentration of the polymer solution is 10 mg / mL to 100 mg / mL.

7. The method for preparing a ferroelectric polymer having a morphotropic phase boundary by irradiation modification according to claim 1, characterized in that: In step (1), the thickness of the polyvinylidene fluoride-trifluoroethylene polymer film is 10 to 100 microns.

8. The method for preparing a ferroelectric polymer having a morphotropic phase boundary by irradiation modification according to claim 1, characterized in that: In step (1), the heating film forming comprises: dissolving the polyvinylidene fluoride-trifluoroethylene polymer having a ferroelectric phase in an organic solvent to form a polymer solution, casting the polymer solution on the surface of the substrate, and heating to form a film.

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

10. A ferroelectric polymer having a morphotropic phase boundary, characterized in that: The ferroelectric polymer with a morphotropic phase boundary is prepared by the method for preparing a ferroelectric polymer with a morphotropic phase boundary by irradiation modification as described in any one of claims 1 to 9.

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