Polymer-based piezoelectric nano composite material with high piezoelectric coefficient and preparation method of polymer-based piezoelectric nano composite material
Barium titanate/polyvinylidene fluoride precursor composite films were prepared by solution casting and subjected to biaxial stretching and DC polarization treatment, which solved the problem of low piezoelectric coefficient of piezoelectric materials and realized piezoelectric nanocomposites with high piezoelectric performance and low cost.
Patent Information
- Application Number
- CN202511613019.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-06
- Publication Date
- 2026-02-03
AI Technical Summary
Existing piezoelectric materials have low piezoelectric coefficients, poor sensing performance, and high manufacturing costs, which limits their widespread application.
A barium titanate/polyvinylidene fluoride precursor composite film was prepared by solution casting. The piezoelectric properties were enhanced by biaxial stretching and DC polarization treatment to orient the dipoles inside the nanocomposite material.
The prepared polymer-based piezoelectric nanocomposite material has excellent piezoelectric properties, with a d33 piezoelectric coefficient of up to 53.2 pC/N and an electromechanical coupling coefficient k33 of up to 0.32. The cost is lower than that of chemically modified PVDF binary and ternary copolymers.
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Figure CN121449937A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of sensing materials technology, specifically to a polymer-based piezoelectric nanocomposite material with a high voltage coefficient and its preparation method. Background Technology
[0002] When piezoelectric materials are subjected to external stress, bound charges are generated on the corresponding surfaces, resulting in the piezoelectric effect. The electromechanical conversion capabilities of piezoelectric materials make them important in fields such as vibration sensors, transducers, and energy harvesting equipment.
[0003] Among the mainstream piezoelectric materials currently available, inorganic piezoelectric ceramics have high piezoelectric coefficients, but they suffer from high stiffness and poor environmental adaptability. Organic polymer piezoelectric materials, such as polyvinylidene fluoride (PVDF), while flexible and easily deformable, have piezoelectric coefficients of only 10–30 pC / N, and their electromechanical coupling coefficient, reflecting the efficiency of mechanical-to-electrical energy conversion, is only 0.1–0.2. Chemically modified PVDF copolymers, such as PVDF-TrFE and PVDF-TrFE-CFE, offer enhanced piezoelectric properties, but their production costs increase significantly, exceeding 100 yuan per gram. These drawbacks limit the widespread application of piezoelectric materials.
[0004] Currently, nanocomposite methods are commonly used to prepare novel piezoelectric materials. This method combines piezoelectric polymers with other inorganic or organic nanoreinforcements in some form, using the reinforcements to impart additional piezoelectricity to the material or enhance the original piezoelectricity of the polymer matrix. Currently, commonly used reinforcements are various inorganic piezoelectric ceramic nanoparticles, such as barium titanate and lead zirconate titanate. These inorganic nanomaterials have piezoelectric coefficients far exceeding those of PVDF, and their composite composition can directly improve the piezoelectric properties of the composite material. However, existing nanocomposite methods for preparing piezoelectric materials still suffer from drawbacks such as low piezoelectric coefficients and poor sensing performance. Summary of the Invention
[0005] This application provides a polymer-based piezoelectric nanocomposite material with a high piezoelectric coefficient and its preparation method, aiming to solve the technical problems of low piezoelectric coefficient and poor sensing performance of piezoelectric materials prepared by existing technologies.
[0006] To achieve the above objectives, the present application adopts the following technical solution.
[0007] A first aspect of this application provides a method for preparing a polymer-based piezoelectric nanocomposite material with a high piezoelectric coefficient, comprising:
[0008] S1, barium titanate nanoparticles are added to N,N-dimethylformamide and ultrasonically dispersed evenly; then polyvinylidene fluoride is added and heated and stirred until dissolved to obtain the precursor solution;
[0009] The precursor liquid is coated onto the substrate to form a film, which is then dried and quenched at high temperature to form a thin film.
[0010] The film is peeled off from the substrate to obtain the barium titanate / polyvinylidene fluoride precursor composite film.
[0011] S2, the precursor composite film is cut into thin sheets and subjected to biaxial stretching treatment by a stretching machine;
[0012] S3. Electrodes are deposited on both sides of the precursor composite film after biaxial stretching treatment, and then subjected to DC polarization treatment to obtain polymer-based piezoelectric nanocomposite material.
[0013] Preferably, the size of the barium titanate nanoparticles is 50~200nm; the polyvinylidene fluoride is a powder.
[0014] Preferably, the mass ratio of the barium titanate nanoparticles, polyvinylidene fluoride, and N,N-dimethylformamide is 0.02~0.08:6~8:30~42.
[0015] Preferably, in S1, the coating is performed by a scraper, and the scale of the scraper is set to 600~1200 μm.
[0016] Preferably, the high-temperature quenching temperature in S1 is 180~220℃, and the holding time is 2~3h;
[0017] The drying temperature is 60~70℃.
[0018] Preferably, in S2, the thin sheet is square, with a size of 7cm×7cm ~ 12cm×12cm.
[0019] Preferably, the process parameters for the biaxial stretching treatment in S2 are:
[0020] The stretching temperature is 155℃~175℃, the stretching rate is 5~100 mm / s, and the stretching ratio is 200~300%.
[0021] Preferably, the electrode in S3 is a copper electrode with a diameter of 1.2~2cm.
[0022] Preferably, an oil bath polarization device is used for DC polarization treatment in S3;
[0023] The electric field strength of the DC polarization treatment is 100~200 MV / m, and the time is 30~40 min.
[0024] A second aspect of this application provides a polymer-based piezoelectric nanocomposite material with a high piezoelectric coefficient prepared by the above-described preparation method.
[0025] Compared with the prior art, the beneficial effects of this application are as follows:
[0026] This application first prepares a composite film of polyvinylidene fluoride homopolymer and barium titanate precursor by solution casting, then rapidly orients the nanocomposite material above the melting point of the polymer using a biaxial stretching process, and finally orients the dipoles inside the nanocomposite material under an electric field by DC polarization to obtain a polymer-based piezoelectric nanocomposite material. The doping of trace amounts of barium titanate nanoparticles helps to construct an organic-inorganic interface in the composite material and increases the content of the polar phase in PVDF through interfacial interactions. Simultaneously, the extremely low addition amount avoids the reduction in durability and breakdown resistance of the composite material due to nanoparticle agglomeration. Biaxial stretching allows for full orientation of the polyvinylidene fluoride molecular chains during the stretching process, significantly increasing the β-phase content of the all-trans conformation, thereby improving the spontaneous polarization and piezoelectric coefficient of the material. DC polarization oriented the dipoles within the composite material, maximizing the piezoelectric properties of the piezoelectric nanocomposite material.
[0027] The preparation method of this application has the potential for large-scale manufacturing. Its raw materials are conventional PVDF homopolymer powder and a very small amount of inorganic nanoparticles. The production cost is much lower than that of existing chemically modified PVDF binary and ternary copolymer products.
[0028] The nanocomposite material prepared by biaxial stretching and DC polarization in this application exhibits excellent piezoelectric properties, and its d 33 The piezoelectric coefficient can reach 53.2 pC / N, and the electromechanical coupling coefficient k 33 It can reach 0.32. Attached Figure Description
[0029] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0030] Figure 1 Images of the precursor composite film prepared in Example 1 before and after biaxial stretching;
[0031] Figure 2 The polarization curves of the polymer-based piezoelectric nanocomposites of Examples 1 and Comparative Examples 1-3 are shown.
[0032] Figure 3 The electric field-strain relationship and piezoelectric coefficient test diagrams are for the polymer-based piezoelectric nanocomposites of Examples 1 and Comparative Examples 1-3. Detailed Implementation
[0033] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.
[0034] In the following description of this embodiment, the terms "including", "comprising", "having", and "containing" are all open-ended terms, meaning that they include but are not limited to.
[0035] In the following description of this embodiment, the term "and / or" is used to describe the association relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, B existing alone, and A and B existing simultaneously. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.
[0036] In the following description of this embodiment, the term "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.
[0037] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms "a" and "the" as used in the embodiments of this application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.
[0038] Those skilled in the art should understand that, in the following description of the embodiments of this application, the sequence of numbers does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.
[0039] Those skilled in the art will understand that the numerical ranges in the embodiments of this application should be understood as each intermediate value between the upper and lower limits of the specifically disclosed range. Each smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this application. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.
[0040] Unless otherwise stated, the technical / scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. While this application describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this application. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.
[0041] In a first aspect, this application provides a method for preparing a polymer-based piezoelectric nanocomposite material with a high piezoelectric coefficient. First, a composite film of polyvinylidene fluoride homopolymer and barium titanate precursor is prepared by solution casting. Then, the nanocomposite material is rapidly oriented above the melting point of the polymer using a biaxial stretching process. Finally, the dipoles inside the nanocomposite material are oriented under an electric field by DC polarization to obtain the polymer-based piezoelectric nanocomposite material. Specifically, it includes:
[0042] S1, barium titanate nanoparticles are added to N,N-dimethylformamide and ultrasonically dispersed evenly; then polyvinylidene fluoride is added and heated and stirred until dissolved to obtain the precursor solution;
[0043] In this application, the size of the barium titanate nanoparticles is preferably 50~200nm, and the polyvinylidene fluoride is preferably in powder form; the mass ratio of the barium titanate nanoparticles, polyvinylidene fluoride and N,N-dimethylformamide is preferably 0.02~0.08:6~8:30~42; and the heating and stirring time is preferably 2~4h.
[0044] The precursor liquid is coated onto the substrate to form a film, which is then dried and quenched at high temperature to form a thin film.
[0045] Specifically, the precursor liquid is applied to the substrate using a doctor blade, with the doctor blade set to a scale of 600-1200 μm. The substrate is preferably a glass plate.
[0046] The substrate after coating is dried at 60~70℃ to remove the solvent; then it is heated to 180~220℃ and held for 2~3 hours, and then quickly placed in ice water to quench the film.
[0047] The film is peeled off from the substrate to obtain the barium titanate / polyvinylidene fluoride precursor composite film.
[0048] In this application, the preparation of barium titanate / polyvinylidene fluoride precursor composite films has strict requirements regarding solution concentration, coating temperature, and quenching temperature. Only within the parameter range specified in this application can a smooth, pore-free precursor film meeting the required composite tensile quality be prepared.
[0049] S2, the precursor composite film is cut into thin sheets and subjected to biaxial stretching treatment by a stretching machine;
[0050] In this application, the precursor composite film is cut into square sheets with dimensions of 7cm×7cm to 12cm×12cm, and then subjected to biaxial stretching using a stretching machine. The process parameters for biaxial stretching are: stretching temperature of 155℃ to 175℃, stretching rate of 5 to 100 mm / s, and stretching ratio of 200 to 300%. The stretching temperature, stretching rate, and stretching ratio must be strictly controlled within these ranges; otherwise, problems such as film melting and film breakage may occur, leading to stretching failure.
[0051] S3. Electrodes are deposited on both sides of the precursor composite film after biaxial stretching treatment, and then subjected to DC polarization treatment to obtain polymer-based piezoelectric nanocomposite material.
[0052] In this application, electrodes are formed on both sides of the precursor composite film by vapor deposition. The electrodes are preferably copper electrodes with a diameter of 1.2 to 2 cm.
[0053] This application employs an oil bath polarization device for DC polarization treatment. DC polarization requires strict control of the polarization electric field. An excessively low polarization electric field cannot orient the material's dipoles, resulting in low piezoelectric properties. Conversely, an excessively high polarization electric field can easily cause electrical breakdown, leading to piezoelectric material failure. In this application, the electric field strength for DC polarization treatment is 100–200 MV / m, and the treatment time is 30–40 min.
[0054] In this application, the doping of trace amounts of barium titanate nanoparticles helps to construct an organic-inorganic interface in the composite material and increase the content of the polar phase in PVDF through interfacial interactions. At the same time, the extremely low addition amount avoids the reduction in the durability and breakdown resistance of the composite material due to nanoparticle agglomeration. Biaxial stretching can fully orient the molecular chains of polyvinylidene fluoride during the stretching process, which greatly increases the content of the β phase in the all-trans conformation, thereby improving the spontaneous polarization and piezoelectric coefficient of the material. DC polarization can oriented the dipoles in the composite material, thereby maximizing the piezoelectric properties of the piezoelectric nanocomposite material.
[0055] The preparation method of this application has the potential for large-scale manufacturing. Its raw materials are conventional PVDF homopolymer powder and a very small amount of inorganic nanoparticles. The production cost is much lower than that of existing chemically modified PVDF binary and ternary copolymer products.
[0056] Secondly, this application provides a polymer-based piezoelectric nanocomposite material prepared by the above-described method. The nanocomposite material prepared by biaxial stretching and DC polarization in this application exhibits excellent piezoelectric properties, with its d... 33The piezoelectric coefficient can reach 53.2 pC / N, and the electromechanical coupling coefficient k 33 It can reach 0.32.
[0057] The present application will be further illustrated by the following examples.
[0058] Example 1
[0059] This embodiment provides a method for preparing a polymer-based piezoelectric nanocomposite material, including:
[0060] S1, 0.04 g of barium titanate nanoparticles with an average diameter of 100 nm were added to 34 g of DMF and sonicated for 30 min to disperse the nanoparticles uniformly; then 7.96 g of PVDF powder was added and stirred at 60 °C for 4 h until the PVDF powder was completely dissolved to obtain the precursor solution.
[0061] The precursor solution was poured onto a flat glass plate measuring 24 cm × 36 cm. The coating scale of the scraper was set to 1000 μm, and the mixture was uniformly coated into a film. The glass plate was placed in a vacuum oven and left overnight at 60°C to remove the solvent. The glass plate was then kept in the oven at 200°C for 2 hours. The glass plate was then removed and placed in ice water to quench the film. The heat-treated composite film was peeled off the glass plate to obtain the precursor composite film.
[0062] S2, the precursor composite film is cut into 10 cm × 10 cm sheets, fixed on the fixture of the stretching machine, and then the stretching temperature is set to 165℃, the stretching rate is 70 mm / s, and the stretching ratio is 270% to perform biaxial stretching treatment on the film.
[0063] S3. Circular copper electrodes with a diameter of 1.2 cm are deposited on both sides of the stretched composite film by vapor deposition. The film is then placed in an oil bath polarization device and subjected to DC polarization treatment for 30 min under an electric field strength of 200 MV / m to obtain a polymer-based piezoelectric nanocomposite material.
[0064] Example 2
[0065] This embodiment provides a method for preparing a polymer-based piezoelectric nanocomposite material, including:
[0066] S1, 0.06 g of barium titanate nanoparticles with an average diameter of 100 nm were added to 32 g of DMF and sonicated for 30 min to disperse the nanoparticles uniformly; then 7.94 g of PVDF powder was added and stirred at 60 °C for 4 h until the PVDF powder was completely dissolved to obtain the precursor solution.
[0067] The remaining steps are the same as in Example 1;
[0068] S2 is the same as in Example 1;
[0069] S3 is the same as in Example 1.
[0070] Example 3
[0071] This embodiment provides a method for preparing a polymer-based piezoelectric nanocomposite material, including:
[0072] S1 is the same as in Example 1;
[0073] S2, the precursor composite film is cut into 10 cm × 10 cm sheets, fixed on the fixture of the stretching machine, and then the stretching temperature is set to 165℃, the stretching rate is 70 mm / s, and the stretching ratio is 200% to perform biaxial stretching treatment on the film.
[0074] S3. Circular copper electrodes with a diameter of 1.2 cm are deposited on both sides of the stretched composite film by vapor deposition. The film is then placed in an oil bath polarization device and subjected to DC polarization treatment for 30 min under an electric field strength of 150 MV / m to obtain a polymer-based piezoelectric nanocomposite material.
[0075] Example 4
[0076] This embodiment provides a method for preparing a polymer-based piezoelectric nanocomposite material, including:
[0077] S1, 0.02 g of barium titanate nanoparticles with an average diameter of 100 nm were added to 34 g of DMF and sonicated for 30 min to disperse the nanoparticles uniformly; then 7.98 g of PVDF powder was added and stirred at 60 °C for 4 h until the PVDF powder was completely dissolved to obtain the precursor solution.
[0078] The precursor solution was poured onto a flat glass plate measuring 24 cm × 36 cm. The coating scale of the scraper was set to 1000 μm, and the mixture was uniformly coated into a film. The glass plate was placed in a vacuum oven and left overnight at 60°C to remove the solvent. The glass plate was then kept in the oven at 200°C for 2 hours. The glass plate was then removed and placed in ice water to quench the film. The heat-treated composite film was peeled off the glass plate to obtain the precursor composite film.
[0079] S2, the precursor composite film is cut into 10 cm × 10 cm sheets, fixed on the fixture of the stretching machine, and then the stretching temperature is set to 165℃, the stretching rate is 70 mm / s, and the stretching ratio is 220% to perform biaxial stretching treatment on the film.
[0080] S3 is the same as in Example 1.
[0081] Comparative Example 1
[0082] The difference between Comparative Example 1 and Example 1 is that barium titanate nanoparticles were not added. Its preparation method includes:
[0083] S1, 8 g of PVDF powder was added to 34 g of DMF and stirred at 60°C for 4 h until the PVDF powder was completely dissolved to obtain the precursor solution;
[0084] The precursor solution was poured onto a flat glass plate measuring 24 cm × 36 cm. The coating scale of the scraper was set to 1000 μm, and the mixture was uniformly coated into a film. The glass plate was placed in a vacuum oven and left overnight at 60°C to remove the solvent. The glass plate was then kept in the oven at 200°C for 2 hours. The glass plate was then removed and placed in ice water to quench the film. The heat-treated composite film was peeled off the glass plate to obtain the precursor composite film.
[0085] S2 is the same as in Example 1;
[0086] S3 is the same as in Example 1.
[0087] Comparative Example 2
[0088] The difference between Comparative Example 2 and Example 1 is that no stretching treatment was performed, and its preparation method includes:
[0089] S1 is the same as in Example 1;
[0090] S2, the composite film prepared in S1 is double-sided vapor-deposited with a circular copper electrode with a diameter of 1.2 cm, and then the film is placed in an oil bath polarization device and subjected to DC polarization treatment for 30 min under an electric field strength of 200 MV / m to obtain a polymer-based piezoelectric nanocomposite material.
[0091] Comparative Example 3
[0092] The difference between Comparative Example 3 and Example 1 is that no DC polarization treatment was performed, and its preparation method includes:
[0093] This embodiment provides a method for preparing a polymer-based piezoelectric nanocomposite material, including:
[0094] S1 is the same as in Example 1;
[0095] S2, the precursor composite film is cut into 10 cm × 10 cm sheets, fixed on the fixture of the stretching machine, and then the stretching temperature is set to 165℃, the stretching rate is 70 mm / s, and the stretching ratio is 270%. The film is subjected to biaxial stretching treatment to obtain polymer-based piezoelectric nanocomposite material.
[0096] Images of the precursor composite film prepared in Example 1 before and after biaxial stretching are shown below. Figure 1 As shown. Figure 1 The left image shows the product before biaxial stretching, and the right image shows the product after biaxial stretching. From Figure 1 As can be seen, the film was successfully biaxially stretched with uniform stretching dimensions. No defects such as pores appeared in the film during the stretching process, and the thickness of the stretched film was approximately 10~12 μm.
[0097] The polarization curves of the polymer-based piezoelectric nanocomposites of Examples 1, 2, and 3 are shown in the figure. Figure 2 As shown. From Figure 2 It can be seen that the spontaneous polarization of the film in Comparative Example 2 without biaxial stretching treatment is extremely low. After biaxial stretching treatment, the spontaneous polarization value increases due to the increased proportion of polar phase in polyvinylidene fluoride. Further DC polarization treatment of the film based on biaxial stretching can significantly enhance the spontaneous polarization, as seen in Examples 1 and 3. This is because the DC polarization process orients the dipoles inside the film, further increasing the film's orientation and leading to an increase in spontaneous polarization. Furthermore, compared to the pure PVDF biaxially stretched film of Comparative Example 1 without barium titanate nanoparticles, the nanocomposite film of Example 1 with added barium titanate nanoparticles also has a higher polarization value. This is because the interaction force between the nanoparticles and polyvinylidene fluoride induces the formation of an additional polar phase, leading to an overall increase in the polarization value of the material.
[0098] The electric field-strain relationship and piezoelectric coefficient of the polymer-based piezoelectric nanocomposites of Examples 1, 2, and 3 are as follows: Figure 3 As shown. From Figure 3 It is clear that the unpolarized film of Comparative Example 3 has an extremely low piezoelectric coefficient of only 0.17 pC / N, indicating that its internal dipoles are completely unoriented and cancel each other out, thus exhibiting almost no piezoelectricity. The unbiaxially stretched film of Comparative Example 2, even after polarization treatment, has a piezoelectric coefficient of only 13.8 pC / N, indicating that the content of the piezoelectric polar phase inside is too low. However, after biaxial stretching treatment, the nanocomposite film of Example 1, due to the significant increase in the content of the polar phase, and after high-voltage polarization, has a piezoelectric coefficient of up to 53.2 pC / N.
[0099] The piezoelectric properties of the polymer-based piezoelectric nanocomposites of the embodiments and comparative examples of this application were tested, and the results are shown in Table 1.
[0100] Table 1. Piezoelectric property data of polymer-based piezoelectric nanocomposites in the examples and comparative examples.
[0101]
[0102] Table 1 shows that to achieve optimal piezoelectric properties in the thin film material, three steps are indispensable: adding barium titanate nanoparticles, biaxial stretching of the film, and subsequent high-voltage polarization of the film. Comparing Examples 1 with Examples 2-4 and the comparative examples, it is evident that, without damaging the film material, a higher stretching ratio and a higher polarization electric field result in better piezoelectric properties. Table 1 also shows that the relationship between the content of barium titanate nanoparticles and piezoelectric properties exhibits a trend of first increasing and then decreasing. Lower nanoparticle content can induce polar phases within the polymer matrix, enhancing piezoelectricity. However, excessively high barium titanate content can cause particle agglomeration and leakage current, reducing piezoelectricity. Under the conditions of 0.5 wt% barium titanate nanoparticle content, a biaxial stretching ratio of 270%, and a DC polarization electric field strength of 200 MV / m, the piezoelectric nanocomposite material with optimal piezoelectric properties can be obtained.
[0103] Although this application has been described in detail in this specification with general descriptions and specific embodiments, some modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, such modifications or improvements made without departing from the spirit of this application are all within the scope of protection claimed in this application.
Claims
1. A method for preparing a polymer-based piezoelectric nanocomposite material with a high piezoelectric coefficient, characterized in that, include: S1, Barium titanate nanoparticles are added to N,N-dimethylformamide and ultrasonically dispersed evenly; Add polyvinylidene fluoride and heat and stir until dissolved to obtain the precursor solution; The precursor liquid is coated onto the substrate to form a film, which is then dried and quenched at high temperature to form a thin film. The film is peeled off from the substrate to obtain the barium titanate / polyvinylidene fluoride precursor composite film. S2, the precursor composite film is cut into thin sheets and subjected to biaxial stretching treatment by a stretching machine; S3. Electrodes are deposited on both sides of the precursor composite film after biaxial stretching treatment, and then subjected to DC polarization treatment to obtain polymer-based piezoelectric nanocomposite material.
2. The preparation method according to claim 1, characterized in that, The size of the barium titanate nanoparticles is 50~200nm; the polyvinylidene fluoride is a powder.
3. The preparation method according to claim 1, characterized in that, The mass ratio of barium titanate nanoparticles, polyvinylidene fluoride, and N,N-dimethylformamide is 0.02~0.08:6~8:30~42.
4. The preparation method according to claim 1, characterized in that, In S1, coating is performed using a scraper with a scale set to 600~1200 μm.
5. The preparation method according to claim 1, characterized in that, The high-temperature quenching temperature of S1 is 180~220℃, and the holding time is 2~3h; The drying temperature is 60~70℃.
6. The preparation method according to claim 1, characterized in that, In S2, the thin sheet is square, with dimensions of 7cm×7cm ~ 12cm×12cm.
7. The preparation method according to claim 1, characterized in that, The process parameters for the biaxial stretching process described in S2 are: The stretching temperature is 155℃~175℃, the stretching rate is 5~100 mm / s, and the stretching ratio is 200~300%.
8. The preparation method according to claim 1, characterized in that, The electrode described in S3 is a copper electrode with a diameter of 1.2~2cm.
9. The preparation method according to claim 1, characterized in that, S3 uses an oil bath polarization device for DC polarization. The electric field strength of the DC polarization treatment is 100~200 MV / m, and the time is 30~40 min.
10. A polymer-based piezoelectric nanocomposite material with a high piezoelectric coefficient prepared by the preparation method according to any one of claims 1-9.