Crystal form induced PVDF piezoelectric film and preparation method thereof

Abstract

The invention provides a crystal form induced PVDF piezoelectric film and a preparation method thereof, and relates to the technical field of piezoelectric materials. The crystal form induced PVDF piezoelectric film is prepared from the following raw materials: polyvinylidene fluoride, polyvinylpyrrolidone, nano zinc oxide and an aprotic polar solvent, the preparation method of the crystal form induced PVDF piezoelectric film comprises the following steps: S1, mixing and dissolving polyvinylidene fluoride, polyvinylpyrrolidone and an aprotic polar solvent; s2, adding nano zinc oxide into the solution; and S3, preparing the piezoelectric film material by adopting a solvent heating and evaporating method. Zinc oxide which is low in price and has a piezoelectric effect is used as an inducer, and a thin-layer material with excellent piezoelectric property and degradation property is formed by utilizing the piezoelectric property of zinc oxide while zinc oxide induces formation of beta-phase PVDF.

Description

Technical Field

[0001] The invention relates to the technical field of piezoelectric materials, in particular to a crystal-form induced PVDF piezoelectric film and a preparation method thereof. Background Art

[0002] PVDF piezoelectric material is a new type of polymer piezoelectric material. Its unique dielectric effect, piezoelectric effect and thermoelectric effect make it widely used in many fields. PVDF piezoelectric material is a new type of polymer piezoelectric material. Its unique dielectric effect, piezoelectric effect and thermoelectric effect make it widely used in many fields. Wu et al. found that the optimal β content and piezoelectric coefficient (d33) of oriented electrospun PVDF reached 88% and 27.4pC / N respectively; and the addition of carbon nanotubes induced charge accumulation at the material boundary, promoted the arrangement of PVDF chains in the β phase conformation, and increased the β phase content to 89%. Magnesium chromite nanomaterials show properties similar to other types of ceramic compounds, and have not been used as fillers in PVDF to enhance the β phase. Ponnan synthesized magnesium chromite nanocrystalline powder (MNC) by template co-precipitation method. The addition of MNC as an active filler and the electrospinning effect induced an electroactive polar β crystal phase in PVDF electrospun nanofibers, enhancing the ferroelectric β crystal phase and piezoelectric properties of PVDF. Vijayakumar RP added silver nanoparticles to PVDF for electrospinning. The electron-rich Ag-NPs interacted with the fluorine atoms in PVDF to enhance polarization, effectively inducing the formation of the β phase and improving the piezoelectric performance. However, the existing piezoelectric materials are mainly inorganic materials. Although PVDF has been reported as a piezoelectric material, there are still technical difficulties in preparing the β crystal phase with excellent piezoelectric performance. Summary of the invention

[0003] In view of the shortcomings of the prior art, the present invention provides a crystal-induced PVDF piezoelectric film and a preparation method thereof, which realizes the configuration transformation of PVDF and the piezoelectric effect of the thin layer material. The low price and polarization effect of zinc oxide crystals are utilized to solve the formation problem of β-phase PVDF film, and prepare PVDF thin layer material with excellent piezoelectric properties.

[0004] To achieve the above objectives, the present invention is implemented through the following technical scheme: a crystal-induced PVDF piezoelectric film, comprising the following raw materials: polyvinylidene fluoride, polyvinyl pyrrolidone, nano zinc oxide and aprotic polar solvent; the mass ratio of nano zinc oxide, polyvinylidene fluoride and polyvinyl pyrrolidone is (0.03-0.1):1:(0.01-0.05), and the mass ratio of the polyvinylidene fluoride and polyvinyl pyrrolidone to the aprotic polar solvent is (1-3):10.

[0005] Preferably, a method for preparing a crystal-induced PVDF piezoelectric film is characterized by comprising the following steps:

[0006] S1. Preparation of PVDF solution

[0007] Add polyvinylidene fluoride and polyvinyl pyrrolidone into a beaker, and add a non-protonic polar solvent into the beaker, heat and stir to dissolve, stop heating and continue stirring for 12 hours after complete dissolution, then vacuum the solution in the beaker to remove bubbles, and obtain a PVDF solution;

[0008] S2. Further preparation of solution

[0009] Add nano zinc oxide to the prepared solution and continue stirring to obtain a uniform and stable solution;

[0010] S3. Film making

[0011] The obtained solution was allowed to stand for degassing using an ultrasonic degassing machine, the solution was evenly spread on a glass plate, and a piezoelectric thin film material was prepared by a heating and solvent evaporation method.

[0012] Preferably, the nano zinc oxide is a shuttle-shaped zinc oxide or a flaky zinc oxide having a crystalline structure.

[0013] Preferably, the aprotic polar solvent is any one of dimethylacetamide, dimethylformamide or N-methylpyrrolidone.

[0014] Preferably, in step S1, the temperature of heating and stirring is 30-100°C.

[0015] Preferably, in the step S3, the heating evaporation temperature is 60 to 120° C. and the time is 1 to 24 hours.

[0016] The present invention provides a crystal-induced PVDF piezoelectric film and a preparation method thereof, which has the following beneficial effects:

[0017] 1. The present invention uses zinc oxide, which is cheap and has a piezoelectric effect, as an inducing agent. While zinc oxide induces the formation of β-phase PVDF, zinc oxide itself has piezoelectric properties, thereby forming a thin layer material with excellent piezoelectric properties and degradation properties. The prepared β-phase PVDF piezoelectric thin layer material has a β-phase conversion rate of 80-90%, and a RhB degradation rate of more than 50% under ultrasonic conditions, which has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The XRD crystal image comparison diagram of the pure PVDF crystal image of the present invention (left) and the PVDF piezoelectric film prepared in Example 1 (right);

[0019] Figure 2 A comparison chart of the degradation rate of RhB by pure PVDF of the present invention (left) and the PVDF piezoelectric film prepared in Example 1 (right);

[0020] Figure 3 The XRD crystal image comparison diagram of the PVDF crystal image of the present invention (left) and the PVDF piezoelectric film prepared in Example 2 (right);

[0021] Figure 4 This is a comparison chart of the degradation rate of RhB of pure PVDF of the present invention (left) and the PVDF piezoelectric film prepared in Example 2 (right). DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] Embodiment 1:

[0024] The embodiment of the present invention provides a method for preparing a crystal-induced PVDF piezoelectric film, comprising the following steps:

[0025] S1. Preparation of PVDF solution

[0026] 4.8 g of polyvinylidene fluoride and 0.15 g of polyvinyl pyrrolidone were added to a beaker, and 50 mL of dimethylacetamide was added to the beaker, and the mixture was heated and stirred at 60°C to dissolve. After the mixture was completely dissolved, heating was stopped and stirring was continued for 12 h. The solution in the beaker was then vacuumed to remove bubbles to obtain a PVDF solution.

[0027] S2. Further preparation of solution

[0028] Add 1% of the amount of PVDF added to the prepared solution, and stir at 60°C for 5 hours to obtain a uniform and stable solution;

[0029] S3. Film making

[0030] The obtained solution was allowed to stand and then degassed using an ultrasonic defoamer. The solution was evenly spread on a glass plate and dried in an oven at 80° C. for 5 h using a heating evaporation solvent method to obtain a thin film material.

[0031] Embodiment 2:

[0032] The embodiment of the present invention provides a method for preparing a crystal-induced PVDF piezoelectric film, comprising the following steps:

[0033] S1. Preparation of PVDF solution

[0034] 4.8 g of polyvinylidene fluoride and 0.15 g of polyvinyl pyrrolidone were added to a beaker, and 50 mL of dimethylacetamide was added to the beaker, and the mixture was heated and stirred at 60°C to dissolve. After the mixture was completely dissolved, heating was stopped and stirring was continued for 12 h. The solution in the beaker was then vacuumed to remove bubbles to obtain a PVDF solution.

[0035] S2. Further preparation of solution

[0036] Add 1% of the polyvinylidene fluoride added amount of flaky zinc oxide to the above prepared solution, and stir at 60°C for 5 hours to obtain a uniform and stable solution;

[0037] S3. Film making

[0038] The obtained solution was allowed to stand and then degassed using an ultrasonic defoamer. The solution was evenly spread on a glass plate and dried in an oven at 70° C. for 5 h using a heating evaporation solvent method to obtain a thin film material.

[0039] Embodiment three:

[0040] The embodiment of the present invention provides a method for preparing a crystal-induced PVDF piezoelectric film, comprising the following steps:

[0041] S1. Preparation of PVDF solution

[0042] 4.8 g of polyvinylidene fluoride and 0.15 g of polyvinyl pyrrolidone were added to a beaker, and 50 mL of dimethylacetamide was added to the beaker, and the mixture was heated and stirred at 60°C to dissolve. After the mixture was completely dissolved, heating was stopped and stirring was continued for 12 h. The solution in the beaker was then vacuumed to remove bubbles to obtain a PVDF solution.

[0043] S2. Further preparation of solution

[0044] Add 1% of the polyvinylidene fluoride added amount of flaky zinc oxide to the above prepared solution, and stir at 60°C for 5 hours to obtain a uniform and stable solution;

[0045] S3. Film making

[0046] The obtained solution was allowed to stand and then degassed using an ultrasonic defoamer. The solution was evenly spread on a glass plate and dried in an oven at 80° C. for 5 h using a heating evaporation solvent method to obtain a thin film material.

[0047] Embodiment 4:

[0048] The embodiment of the present invention provides a method for preparing a crystal-induced PVDF piezoelectric film, comprising the following steps:

[0049] S1. Preparation of PVDF solution

[0050] 4.8 g of polyvinylidene fluoride and 0.15 g of polyvinyl pyrrolidone were added to a beaker, and 50 mL of dimethylacetamide was added to the beaker, and the mixture was heated and stirred at 60°C to dissolve. After the mixture was completely dissolved, heating was stopped and stirring was continued for 12 h. The solution in the beaker was then vacuumed to remove bubbles to obtain a PVDF solution.

[0051] S2. Further preparation of solution

[0052] Add 3% of the polyvinylidene fluoride added amount of flaky zinc oxide to the above prepared solution, and stir at 60°C for 5 hours to obtain a uniform and stable solution;

[0053] S3. Film making

[0054] The obtained solution was allowed to stand and then degassed using an ultrasonic defoamer. The solution was evenly spread on a glass plate and dried in an oven at 80° C. for 5 h using a heating evaporation solvent method to obtain a thin film material.

[0055] Comparative Example 1:

[0056] The comparative example of the present invention provides a method for preparing a crystal-induced PVDF piezoelectric film, comprising the following steps:

[0057] S1. Preparation of PVDF solution

[0058] 4.8 g of polyvinylidene fluoride and 0.15 g of polyvinyl pyrrolidone were added to a beaker, and 50 mL of dimethylacetamide was added to the beaker, and the mixture was heated and stirred at 60°C to dissolve. After the mixture was completely dissolved, heating was stopped and stirring was continued for 12 h. The solution in the beaker was then vacuumed to remove bubbles to obtain a PVDF solution.

[0059] S2. Further preparation of solution

[0060] Without adding zinc oxide, a uniform and stable solution was obtained by stirring at 60 °C for 5 h;

[0061] S3. Film making

[0062] The obtained solution was allowed to stand and then degassed using an ultrasonic defoamer. The solution was evenly spread on a glass plate and dried in an oven at 80° C. for 5 h using a heating evaporation solvent method to obtain a thin film material.

[0063] By comparing Example 1 with Comparative Example 1, it can be seen that the 1% shuttle-shaped nano zinc oxide induced PVDF thin layer material prepared at 60°C has a diffraction peak at 21° in its XRD, which is the same as the XRD diffraction peak of the β-configuration PVDF material. The crystal configuration of the 1% shuttle-shaped nano zinc oxide induced PVDF thin layer material changes from the a configuration to the β configuration.

[0064] By comparing Example 2 with Comparative Example 1, it can be seen that the 1% flaky nano zinc oxide induced PVDF thin layer material prepared at 70°C has a diffraction peak at 21° in its XRD, which is the same as the XRD diffraction peak of the β-configuration PVDF material. The crystal configuration of the 1% flaky nano zinc oxide induced PVDF thin layer material changes from the a configuration to the β configuration.

[0065] By comparing Example 3 with Comparative Example 1, it can be seen that the 1% flaky nano zinc oxide induced PVDF thin layer material prepared at 80°C has a diffraction peak at 21° in its XRD, which is the same as the XRD diffraction peak of the β-configuration PVDF thin layer material. The crystal configuration of the 1% flaky nano zinc oxide induced PVDF thin layer material changes from the a configuration to the β configuration.

[0066] By comparing Example 4 with Comparative Example 1, it can be seen that the 3% flaky nano zinc oxide induced PVDF thin layer material prepared at 80°C has a diffraction peak at 21° in its XRD, which is the same as the XRD diffraction peak of the β-configuration PVDF thin layer material. The crystal configuration of the 3% flaky nano zinc oxide induced PVDF thin layer material changes from the a configuration to the β configuration.

[0067] In summary, the present invention uses zinc oxide, which is inexpensive and has a piezoelectric effect, as an inducing agent. While zinc oxide induces the formation of β-phase PVDF, zinc oxide itself has piezoelectric properties, thereby forming a thin layer material with excellent piezoelectric properties and degradation properties. The prepared β-phase PVDF piezoelectric thin layer material has a β-phase conversion rate of 80-90%, and a RhB degradation rate of more than 50% under ultrasonic conditions, which has good application prospects.

[0068] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A crystal-induced PVDF piezoelectric film, characterized in that: Including the following ingredients: Polyvinylidene fluoride, polyvinyl pyrrolidone, nano zinc oxide and aprotic polar solvent; the mass ratio of nano zinc oxide, polyvinylidene fluoride and polyvinyl pyrrolidone is (0.03-0.1):1:(0.01-0.05), and the mass ratio of the polyvinylidene fluoride and polyvinyl pyrrolidone to the aprotic polar solvent is (1-3):

10.

2. The method for preparing a crystal-induced PVDF piezoelectric film according to claim 1, characterized in that: The following steps are involved: S1. Preparation of PVDF solution Add polyvinylidene fluoride and polyvinyl pyrrolidone into a beaker, and add a non-protonic polar solvent into the beaker, heat and stir to dissolve, stop heating and continue stirring for 12 hours after complete dissolution, then vacuum the solution in the beaker to remove bubbles, and obtain a PVDF solution; S2. Further preparation of solution Add nano zinc oxide to the prepared solution and continue stirring to obtain a uniform and stable solution; S3. Film making The obtained solution was allowed to stand for degassing using an ultrasonic degassing machine, the solution was evenly spread on a glass plate, and a piezoelectric thin film material was prepared by a heating and solvent evaporation method.

3. The crystal-induced PVDF piezoelectric film according to claim 1, characterized in that: The nano zinc oxide is shuttle-shaped zinc oxide or flaky zinc oxide with a crystalline structure.

4. The crystal-induced PVDF piezoelectric film according to claim 1, characterized in that: The aprotic polar solvent is any one of dimethylacetamide, dimethylformamide or N-methylpyrrolidone.

5. The method for preparing a crystal-induced PVDF piezoelectric film according to claim 1, characterized in that: In the step S1, the temperature for heating and stirring is 60°C.

6. The crystal-induced PVDF piezoelectric film and the preparation method thereof according to claim 1, characterized in that: In the step S3, the heating evaporation temperature is 60 to 120° C. and the time is 1 to 24 hours.

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