阅读说明：本技术 一种聚偏氟乙烯基柔性压电材料及其制备方法 (Polyvinylidene fluoride-based flexible piezoelectric material and preparation method thereof ) 是由 方豪杰 贺亦文 张晓云 张斗 袁晰 于 2021-09-10 设计创作，主要内容包括：本发明涉及电子陶瓷材料领域,具体为一种聚偏氟乙烯基柔性压电材料及其制备方法,由以下原料组成：聚偏氟乙烯、尼龙1111、稀土改性氧化石墨烯、聚酰胺酰亚胺接枝Bi-(0.5)Na-(0.5)TiO-(3)-BaTiO-(3)、聚丁二酸丁二醇酯；所述稀土改性氧化石墨烯经过硅烷偶联剂处理,所制备的压电材料具有良好的压电性能和柔韧性好,在维持了聚合物柔韧性的同时提高了材料的压电性能,在可穿戴设备上具有广阔的应用前景。(The invention relates to the field of electronic ceramic materials, in particular to a polyvinylidene fluoride-based flexible piezoelectric material and a preparation method thereof, wherein the polyvinylidene fluoride-based flexible piezoelectric material is prepared from the following raw materials: polyvinylidene fluoride, nylon 1111, rare earth modified graphene oxide and polyamide imide grafted Bi 0.5 Na 0.5 TiO 3 ‑BaTiO 3 Poly (butylene succinate); the prepared piezoelectric material has good piezoelectric property and flexibility, the polymer flexibility is maintained, meanwhile, the piezoelectric property of the material is improved, and the piezoelectric material has a wide application prospect in wearable equipment.)

1. The polyvinylidene fluoride-based flexible piezoelectric material is characterized by comprising the following raw materials:

polyvinylidene fluoride, nylon 1111, rare earth modified graphene oxide and polyamide imide grafted Bi_0.5Na_0.5TiO₃-BaTiO₃Poly (butylene succinate);

and treating the rare earth modified graphene oxide by using a silane coupling agent.

2. The polyvinylidene fluoride-based flexible piezoelectric material of claim 1, which is prepared from the following raw materials in parts by weight:

60-80 parts of polyvinylidene fluoride, 111130-50 parts of nylon, 1-5 parts of rare earth modified graphene oxide and polyamide-imide grafted Bi_0.5Na_0.5TiO₃-BaTiO₃10-20 parts of poly (butylene succinate) and 2-4 parts of poly (butylene succinate);

and treating the rare earth modified graphene oxide by using a coupling agent.

3. The polyvinylidene fluoride-based flexible piezoelectric material of claim 1, wherein the preparation method of the rare earth modified graphene oxide is as follows:

dissolving rare earth oxide with ethanol, adding ethylene diamine tetraacetic acid, urea and ammonium chloride, stirring and mixing uniformly, adjusting the pH of a system to 4-6 with citric acid to obtain a rare earth modified solution, heating to 40-60 ℃, soaking graphene oxide with concentrated nitric acid for 30-50s, taking out, washing with water to neutral, drying, adding into the rare earth modified solution, performing ultrasonic dispersion for 5-10h, taking out, washing and drying.

4. The polyvinylidene fluoride-based flexible piezoelectric material of claim 3, wherein the rare earth modified liquid is composed of the following raw materials in parts by weight:

1-2 parts of rare earth oxide, 0.1-0.5 part of ethylene diamine tetraacetic acid, 0.1-1 part of urea, 0.1-1 part of ammonium chloride, a proper amount of citric acid and 90-100 parts of ethanol.

5. The polyvinylidene fluoride-based flexible piezoelectric material of claim 3, wherein the rare earth oxide is lanthanum oxide.

6. The polyvinylidene fluoride-based flexible piezoelectric material of claim 1, wherein the silane coupling agent is treated by the following method:

adding acetic acid into 95% ethanol to adjust pH to 4.5-5.5, adding silane coupling agent, hydrolyzing for 5-10min, adding rare earth modified graphene oxide, heating to 30-50 deg.C, ultrasonic oscillating for 5-10min, taking out, and oven drying.

7. The polyvinylidene fluoride-based flexible piezoelectric material of claim 1, wherein the polyamideimide is grafted with Bi_0.5Na_0.5TiO₃-BaTiO₃The preparation method comprises the following steps:

dissolving water-based polyamide imide in water, and then adding Bi_0.5Na_0.5TiO₃-BaTiO₃Adding, ultrasonic oscillating for 30-50min, removing water at 60-70 deg.C under reduced pressure, and oven drying the obtained solid.

8. The polyvinylidene fluoride-based flexible piezoelectric material of claim 7, wherein the aqueous polyamideimide is reacted with Bi_0.5Na_0.5TiO₃-BaTiO₃The mass ratio of (1): 70-85.

9. The preparation method of the polyvinylidene fluoride-based flexible piezoelectric material according to any one of claims 1 to 8, which is characterized by comprising the following steps:

adding polyvinylidene fluoride, nylon 1111 and poly (butylene succinate) into a mixed solution consisting of DMF (dimethyl formamide) and acetone, uniformly stirring, and grafting rare earth modified graphene oxide and polyamide imide with Bi_0.5Na_0.5TiO₃-BaTiO₃Adding to obtain spinning solution, performing electrostatic spinning to obtain crude product, hot pressing the crude product at 150 deg.C and 2-4MPa for 30-60s, removing pressure, and maintaining at 80-100 deg.C for 10-50min and recovering to room temperature.

10. The method for preparing polyvinylidene fluoride-based flexible piezoelectric material of claim 9, wherein the electrostatic spinning parameters are as follows: the spinning speed is 2-4mL/h, the voltage is 10-16kV, and the spinning time is 2-4 h.

Technical Field

The invention relates to the field of electronic ceramic materials, in particular to a polyvinylidene fluoride-based flexible piezoelectric material and a preparation method thereof.

Background

The piezoelectric material is an electromechanical coupling functional material capable of rapidly converting stress/strain such as pressure intensity, vibration and the like into an electric signal or converting the electric signal into a signal such as deformation, vibration and the like. The piezoelectric material has the advantages of positive and negative piezoelectric effect, large bandwidth, quick electromechanical response frequency, high energy conversion rate, strong recovery capability and the like, can be used as a sensor and a driver, and is often used as a preferred smart material to be widely applied to an intelligent structure system.

The traditional piezoelectric materials mainly include piezoelectric crystals (including organic matter, oxide, salt and other crystals, especially nanocrystals with specific structure and orientation), piezoelectric ceramics and piezoelectric polymers 3. The piezoelectric polymer has good mechanical property, high chemical stability and natural flexibility, is easy to process, low in manufacturing cost and easy to match with light loads, can be used for manufacturing extremely thin assemblies, and has good prospects in the aspects of intelligent sensing, wearable self-powered devices and the like.

However, compared with inorganic piezoelectric materials, organic piezoelectric materials have lower piezoelectric performance, which limits their applications. Therefore, how to improve the piezoelectric performance of the organic piezoelectric material while maintaining the flexibility of the organic piezoelectric material is the focus of current research.

Disclosure of Invention

The purpose of the invention is as follows: aiming at the defects or improvement requirements of the prior art, the invention provides a polyvinylidene fluoride-based flexible piezoelectric material and a preparation method thereof.

The technical scheme adopted by the invention is as follows:

a polyvinylidene fluoride-based flexible piezoelectric material is composed of the following raw materials:

polyvinylidene fluoride, nylon 1111, rare earth modified graphene oxide and polyamide imide grafted Bi_0.5Na_0.5TiO₃-BaTiO₃Poly (butylene succinate);

and treating the rare earth modified graphene oxide by using a silane coupling agent.

Further, the feed additive comprises the following raw materials in parts by weight:

60-80 parts of polyvinylidene fluoride, 111130-50 parts of nylon, 1-5 parts of rare earth modified graphene oxide and polyamide-imide grafted Bi_0.5Na_0.5TiO₃-BaTiO₃10-20 parts of poly (butylene succinate) and 2-4 parts of poly (butylene succinate);

and treating the rare earth modified graphene oxide by using a coupling agent.

Further, the preparation method of the rare earth modified graphene oxide comprises the following steps:

dissolving rare earth oxide with ethanol, adding ethylene diamine tetraacetic acid, urea and ammonium chloride, stirring and mixing uniformly, adjusting the pH of a system to 4-6 with citric acid to obtain a rare earth modified solution, heating to 40-60 ℃, soaking graphene oxide with concentrated nitric acid for 30-50s, taking out, washing with water to neutral, drying, adding into the rare earth modified solution, performing ultrasonic dispersion for 5-10h, taking out, washing and drying.

Further, the rare earth modified liquid is composed of the following raw materials in parts by weight:

1-2 parts of rare earth oxide, 0.1-0.5 part of ethylene diamine tetraacetic acid, 0.1-1 part of urea, 0.1-1 part of ammonium chloride, a proper amount of citric acid and 90-100 parts of ethanol.

Further, the rare earth oxide is lanthanum oxide.

Further, the silane coupling agent treatment method is as follows:

adding acetic acid into 95% ethanol to adjust pH to 4.5-5.5, adding silane coupling agent, hydrolyzing for 5-10min, adding rare earth modified graphene oxide, heating to 30-50 deg.C, ultrasonic oscillating for 5-10min, taking out, and oven drying.

Further, the polyamideimide is grafted with Bi_0.5Na_0.5TiO₃-BaTiO₃The preparation method comprises the following steps:

dissolving water-based polyamide imide in water, and then adding Bi_0.5Na_0.5TiO₃-BaTiO₃Adding, ultrasonic oscillating for 30-50min, removing water at 60-70 deg.C under reduced pressure, and oven drying the obtained solid.

Further, aqueous polyamideimide and Bi_0.5Na_0.5TiO₃-BaTiO₃The mass ratio of (1): 70-85.

The preparation method of the polyvinylidene fluoride-based flexible piezoelectric material comprises the following steps:

polyvinylidene fluoride, nylon 1111 and poly butylene succinate are added into DMF and propyleneIn a mixed solution composed of ketone, uniformly stirring, and grafting the rare earth modified graphene oxide and the polyamide imide with Bi_0.5Na_0.5TiO₃-BaTiO₃Adding to obtain spinning solution, performing electrostatic spinning to obtain crude product, hot pressing the crude product at 150 deg.C and 2-4MPa for 30-60s, removing pressure, and maintaining at 80-100 deg.C for 10-50min and recovering to room temperature.

Further, the electrostatic spinning parameters: the spinning speed is 2-4mL/h, the voltage is 10-16kV, and the spinning time is 2-4 h.

The invention has the beneficial effects that:

the invention provides a polyvinylidene fluoride-based flexible piezoelectric material, which has the advantages of high flexibility, small density, easy processing, long-term stability under a high electric field and the like, is a piezoelectric polymer with development prospect, compared with an inorganic piezoelectric material, the polyvinylidene fluoride-based material has weaker piezoelectric capability, but the unique flexibility endows the polyvinylidene fluoride-based material with good processing performance, the nylon 1111 has interaction with a polyvinylidene fluoride dipole and better compatibility, the electric activity of the polyvinylidene fluoride can be improved after the polyvinylidene fluoride is added, the piezoelectric performance is improved, the poly (butylene succinate) is used as a semi-crystalline polymer and has excellent mechanical performance, the reduction of the mechanical performance of the material caused by the addition of inorganic substances can be improved after the poly (butylene succinate) is added, the piezoelectric performance is not influenced after the poly (butylene succinate) is added, and the graphene oxide can be used as a conductive material to form micro-capacitance in the material, the piezoelectric property of the material is improved, a large number of folds exist on the surface of the rare earth modified graphene oxide, the electrochemical current density of the graphene oxide can be improved by the large number of folds, and the electrochemical property is improved by a large number of BaTiO₃Report of using with polyvinylidene fluoride, inventor uses Bi after testing_0.5Na_0.5TiO₃-BaTiO₃Replacement of BaTiO₃And to Bi_0.5Na_0.5TiO₃-BaTiO₃The polyamide-imide grafting treatment not only reduces the dosage of electronic ceramic powder and further improves the piezoelectric performance of the material, but also has good compatibility with high polymer after the grafting treatment and good flexibility of the material, and tests show that the material has good compatibility with high polymerThe piezoelectric material prepared by the invention has good piezoelectric performance and good flexibility, the piezoelectric constant is more than or equal to 44.19pC/N, the planar electromechanical coupling coefficient is more than or equal to 0.31, the dielectric loss is less than or equal to 1.08%, the tensile strength is more than or equal to 6.45MPa, the breaking elongation is more than or equal to 220%, the piezoelectric performance of the material is improved while the flexibility of the polymer is maintained, and the piezoelectric material has wide application prospect in wearable equipment.

Drawings

Fig. 1 is an SEM image of a polyvinylidene fluoride-based flexible piezoelectric material prepared in example 1 of the present invention.

Detailed Description

The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

Example 1:

the polyvinylidene fluoride-based flexible piezoelectric material is prepared from the following raw materials in parts by weight:

70 parts of polyvinylidene fluoride, 140 parts of nylon 111140 parts, 3 parts of coupling agent treated rare earth modified graphene oxide and polyamide-imide grafted Bi_0.5Na_0.5TiO₃-BaTiO₃10 parts of polybutylene succinate and 2 parts of polybutylene succinate;

the method for treating the rare earth modified graphene oxide by the coupling agent comprises the following steps:

dissolving lanthanum oxide in ethanol, adding ethylene diamine tetraacetic acid, urea and ammonium chloride, stirring and mixing uniformly, and adjusting the pH of a system to 4 by using citric acid to obtain a rare earth modified solution, wherein the rare earth modified solution is prepared from the following raw materials in parts by weight: 1 part of rare earth oxide, 0.1 part of ethylenediamine tetraacetic acid, 0.2 part of urea, 0.1 part of ammonium chloride, a proper amount of citric acid and 90 parts of ethanol, heating a rare earth modified solution to 50 ℃, soaking graphene oxide in concentrated nitric acid for 30s, taking out, washing with water to be neutral, drying, adding the rare earth modified solution, performing ultrasonic dispersion for 10 hours, taking out, washing and drying for later use, adding acetic acid into 95% ethanol to adjust the pH to 4.5, adding a silane coupling agent A151, hydrolyzing for 10min, adding the rare earth modified graphene oxide, heating to 30 ℃, performing ultrasonic oscillation for 10min, taking out and drying.

Wherein the polyamide imide is grafted with Bi_0.5Na_0.5TiO₃-BaTiO₃The preparation method comprises the following steps:

dissolving water-based polyamide imide in water, and then adding Bi_0.5Na_0.5TiO₃-BaTiO₃Adding aqueous polyamide-imide and Bi_0.5Na_0.5TiO₃-BaTiO₃The mass ratio of (1): and 80, after ultrasonic oscillation for 30min, decompressing and dewatering at 60 ℃, and drying the obtained solid.

The preparation method of the polyvinylidene fluoride-based flexible piezoelectric material comprises the following steps:

adding polyvinylidene fluoride, nylon 1111 and poly (butylene succinate) into a mixed solution consisting of DMF (dimethyl formamide) and acetone, uniformly stirring, and grafting rare earth modified graphene oxide and polyamide imide with Bi_0.5Na_0.5TiO₃-BaTiO₃Adding to obtain spinning solution, and after electrostatic spinning, obtaining a crude product, wherein electrostatic spinning parameters are as follows: spinning at a speed of 2mL/h and a voltage of 10kV for 2h, hot pressing the crude product at 130 ℃ and 2MPa for 40s, removing the pressure, keeping the temperature at 80 ℃ for 20min, and then recovering the room temperature.

Example 2:

the polyvinylidene fluoride-based flexible piezoelectric material is prepared from the following raw materials in parts by weight:

60 parts of polyvinylidene fluoride, 111130 parts of nylon, 1 part of coupling agent treated rare earth modified graphene oxide and polyamide-imide grafted Bi_0.5Na_0.5TiO₃-BaTiO₃10 parts of polybutylene succinate and 2 parts of polybutylene succinate;

the method for treating the rare earth modified graphene oxide by the coupling agent comprises the following steps:

dissolving lanthanum oxide in ethanol, adding ethylene diamine tetraacetic acid, urea and ammonium chloride, stirring and mixing uniformly, and adjusting the pH of a system to 4 by using citric acid to obtain a rare earth modified solution, wherein the rare earth modified solution is prepared from the following raw materials in parts by weight: 1 part of rare earth oxide, 0.1 part of ethylenediamine tetraacetic acid, 0.1 part of urea, 0.1 part of ammonium chloride, a proper amount of citric acid and 90 parts of ethanol, heating a rare earth modified solution to 40 ℃, soaking graphene oxide in concentrated nitric acid for 30s, taking out, washing with water to be neutral, drying, adding the obtained product into the rare earth modified solution, carrying out ultrasonic dispersion for 5 hours, taking out, washing and drying for later use, adding acetic acid into 95% ethanol to enable the pH value to be 4.5, adding a silane coupling agent A151, hydrolyzing for 5min, adding the rare earth modified graphene oxide, heating to 30 ℃, carrying out ultrasonic oscillation for 5min, taking out and drying.

Wherein the polyamide imide is grafted with Bi_0.5Na_0.5TiO₃-BaTiO₃The preparation method comprises the following steps:

dissolving water-based polyamide imide in water, and then adding Bi_0.5Na_0.5TiO₃-BaTiO₃Adding aqueous polyamide-imide and Bi_0.5Na_0.5TiO₃-BaTiO₃The mass ratio of (1): and (70) after ultrasonic oscillation for 30min, carrying out reduced pressure dehydration at 60 ℃, and drying the obtained solid.

The preparation method of the polyvinylidene fluoride-based flexible piezoelectric material comprises the following steps:

adding polyvinylidene fluoride, nylon 1111 and poly (butylene succinate) into a mixed solution consisting of DMF (dimethyl formamide) and acetone, uniformly stirring, and grafting rare earth modified graphene oxide and polyamide imide with Bi_0.5Na_0.5TiO₃-BaTiO₃Adding to obtain spinning solution, and after electrostatic spinning, obtaining a crude product, wherein electrostatic spinning parameters are as follows: spinning at a speed of 2mL/h and a voltage of 10kV for 2h, hot pressing the crude product at 130 ℃ and 2MPa for 30s, removing the pressure, keeping the temperature at 80 ℃ for 10min, and then recovering the room temperature.

Example 3:

the polyvinylidene fluoride-based flexible piezoelectric material is prepared from the following raw materials in parts by weight:

80 parts of polyvinylidene fluoride, 111150 parts of nylon, 5 parts of coupling agent treated rare earth modified graphene oxide and polyamide-imide grafted Bi_0.5Na_0.5TiO₃-BaTiO₃20 parts of polybutylene succinate and 4 parts of polybutylene succinate;

the method for treating the rare earth modified graphene oxide by the coupling agent comprises the following steps:

dissolving lanthanum oxide in ethanol, adding ethylene diamine tetraacetic acid, urea and ammonium chloride, stirring and mixing uniformly, and adjusting the pH of a system to 6 by using citric acid to obtain a rare earth modified solution, wherein the rare earth modified solution is prepared from the following raw materials in parts by weight: 2 parts of rare earth oxide, 0.5 part of ethylenediamine tetraacetic acid, 1 part of urea, 1 part of ammonium chloride, a proper amount of citric acid and 100 parts of ethanol, heating the rare earth modified solution to 60 ℃, soaking graphene oxide in concentrated nitric acid for 50s, taking out, washing with water to be neutral, drying, adding the obtained product into the rare earth modified solution, performing ultrasonic dispersion for 10 hours, taking out, washing and drying for later use, adding acetic acid into 95% ethanol to adjust the pH value to 5.5, adding a silane coupling agent A151, hydrolyzing for 10 minutes, adding the rare earth modified graphene oxide, heating to 50 ℃, performing ultrasonic oscillation for 10 minutes, taking out and drying.

Wherein the polyamide imide is grafted with Bi_0.5Na_0.5TiO₃-BaTiO₃The preparation method comprises the following steps:

dissolving water-based polyamide imide in water, and then adding Bi_0.5Na_0.5TiO₃-BaTiO₃Adding aqueous polyamide-imide and Bi_0.5Na_0.5TiO₃-BaTiO₃The mass ratio of (1): 85, ultrasonically oscillating for 50min, decompressing and dewatering at 70 ℃, and drying the obtained solid.

The preparation method of the polyvinylidene fluoride-based flexible piezoelectric material comprises the following steps:

adding polyvinylidene fluoride, nylon 1111 and poly (butylene succinate) into a mixed solution consisting of DMF (dimethyl formamide) and acetone, uniformly stirring, and grafting rare earth modified graphene oxide and polyamide imide with Bi_0.5Na_0.5TiO₃-BaTiO₃Adding to obtain spinning solution, and after electrostatic spinning, obtaining a crude product, wherein electrostatic spinning parameters are as follows: spinning at a speed of 4mL/h and a voltage of 16kV for 4h, hot pressing the crude product at 150 ℃ and 4MPa for 60s, removing the pressure, keeping the temperature at 100 ℃ for 50min, and recovering the temperature to room temperature.

Example 4:

the polyvinylidene fluoride-based flexible piezoelectric material is prepared from the following raw materials in parts by weight:

60 parts of polyvinylidene fluoride, 111150 parts of nylon, 1 part of coupling agent treated rare earth modified graphene oxide and polyamide-imide grafted Bi_0.5Na_0.5TiO₃-BaTiO₃20 parts of polybutylene succinate and 2 parts of polybutylene succinate;

the method for treating the rare earth modified graphene oxide by the coupling agent comprises the following steps:

dissolving lanthanum oxide in ethanol, adding ethylene diamine tetraacetic acid, urea and ammonium chloride, stirring and mixing uniformly, and adjusting the pH of a system to 6 by using citric acid to obtain a rare earth modified solution, wherein the rare earth modified solution is prepared from the following raw materials in parts by weight: 1 part of rare earth oxide, 0.5 part of ethylenediamine tetraacetic acid, 0.1 part of urea, 1 part of ammonium chloride, a proper amount of citric acid and 90 parts of ethanol, heating the rare earth modified solution to 60 ℃, soaking graphene oxide in concentrated nitric acid for 30s, taking out, washing with water to be neutral, drying, adding the obtained product into the rare earth modified solution, performing ultrasonic dispersion for 10 hours, taking out, washing and drying for later use, adding acetic acid into 95% ethanol to enable the pH value to be 4.5, adding a silane coupling agent A151, hydrolyzing for 10min, adding the rare earth modified graphene oxide, heating to 30 ℃, performing ultrasonic oscillation for 10min, taking out and drying.

Wherein the polyamide imide is grafted with Bi_0.5Na_0.5TiO₃-BaTiO₃The preparation method comprises the following steps:

dissolving water-based polyamide imide in water, and then adding Bi_0.5Na_0.5TiO₃-BaTiO₃Adding aqueous polyamide-imide and Bi_0.5Na_0.5TiO₃-BaTiO₃The mass ratio of (1): and (70) after ultrasonic oscillation for 50min, carrying out reduced pressure dehydration at 60 ℃, and drying the obtained solid.

The preparation method of the polyvinylidene fluoride-based flexible piezoelectric material comprises the following steps:

adding polyvinylidene fluoride, nylon 1111 and poly (butylene succinate) into a mixed solution consisting of DMF (dimethyl formamide) and acetone, uniformly stirring, and grafting rare earth modified graphene oxide and polyamide imide with Bi_0.5Na_0.5TiO₃-BaTiO₃Adding the mixture to obtain a spinning solution, performing electrostatic spinning,obtaining a crude product, wherein electrostatic spinning parameters are as follows: spinning at 4mL/h under 10kV for 4h, hot pressing at 130 deg.C under 4MPa for 30s, removing pressure, keeping at 100 deg.C for 10min, and recovering to room temperature.

Example 5:

the polyvinylidene fluoride-based flexible piezoelectric material is prepared from the following raw materials in parts by weight:

80 parts of polyvinylidene fluoride, 111130 parts of nylon, 5 parts of coupling agent treated rare earth modified graphene oxide and polyamide-imide grafted Bi_0.5Na_0.5TiO₃-BaTiO₃10 parts of polybutylene succinate and 4 parts of polybutylene succinate;

the method for treating the rare earth modified graphene oxide by the coupling agent comprises the following steps:

dissolving lanthanum oxide in ethanol, adding ethylene diamine tetraacetic acid, urea and ammonium chloride, stirring and mixing uniformly, and adjusting the pH of a system to 4 by using citric acid to obtain a rare earth modified solution, wherein the rare earth modified solution is prepared from the following raw materials in parts by weight: 2 parts of rare earth oxide, 0.1 part of ethylenediamine tetraacetic acid, 1 part of urea, 0.1 part of ammonium chloride, a proper amount of citric acid and 100 parts of ethanol, heating the rare earth modified solution to 40 ℃, soaking graphene oxide in concentrated nitric acid for 50s, taking out, washing with water to be neutral, drying, adding the obtained product into the rare earth modified solution, performing ultrasonic dispersion for 5h, taking out, washing and drying for later use, adding acetic acid into 95% ethanol to adjust the pH to 5.5, adding a silane coupling agent A151, hydrolyzing for 5min, adding the rare earth modified graphene oxide, heating to 50 ℃, performing ultrasonic oscillation for 5min, taking out and drying.

Wherein the polyamide imide is grafted with Bi_0.5Na_0.5TiO₃-BaTiO₃The preparation method comprises the following steps:

dissolving water-based polyamide imide in water, and then adding Bi_0.5Na_0.5TiO₃-BaTiO₃Adding aqueous polyamide-imide and Bi_0.5Na_0.5TiO₃-BaTiO₃The mass ratio of (1): 85, ultrasonically oscillating for 30min, decompressing and dewatering at 70 ℃, and drying the obtained solid.

The preparation method of the polyvinylidene fluoride-based flexible piezoelectric material comprises the following steps:

adding polyvinylidene fluoride, nylon 1111 and poly (butylene succinate) into a mixed solution consisting of DMF (dimethyl formamide) and acetone, uniformly stirring, and grafting rare earth modified graphene oxide and polyamide imide with Bi_0.5Na_0.5TiO₃-BaTiO₃Adding to obtain spinning solution, and after electrostatic spinning, obtaining a crude product, wherein electrostatic spinning parameters are as follows: spinning at a speed of 2mL/h and a voltage of 16kV for 2h, hot pressing the crude product at 150 ℃ and 2MPa for 60s, removing the pressure, keeping the temperature at 80 ℃ for 50min, and recovering the room temperature.

Comparative example 1

Comparative example 1 is essentially the same as example 1 except that nylon 1111 is not added.

The polyvinylidene fluoride-based flexible piezoelectric material is prepared from the following raw materials in parts by weight:

70 parts of polyvinylidene fluoride, 3 parts of coupling agent treated rare earth modified graphene oxide and polyamide-imide grafted Bi_0.5Na_0.5TiO₃-BaTiO₃10 parts of polybutylene succinate and 2 parts of polybutylene succinate.

Comparative example 2

Comparative example 2 is essentially the same as example 1 except that no polybutylene succinate is added.

The polyvinylidene fluoride-based flexible piezoelectric material is prepared from the following raw materials in parts by weight:

70 parts of polyvinylidene fluoride, 140 parts of nylon 111140 parts, 3 parts of coupling agent treated rare earth modified graphene oxide and polyamide-imide grafted Bi_0.5Na_0.5TiO₃-BaTiO₃10 parts.

Comparative example 3

Comparative example 3 is substantially the same as example 1 except that graphene oxide is not treated with a coupling agent.

The polyvinylidene fluoride-based flexible piezoelectric material is prepared from the following raw materials in parts by weight:

70 parts of polyvinylidene fluoride, 140 parts of nylon 111140 parts, 3 parts of rare earth modified graphene oxide and polyamide-imide grafted Bi_0.5Na_0.5TiO₃-BaTiO₃10 parts of polybutylene succinate and 2 parts of polybutylene succinate.

Comparative example 4

Comparative example 4 is substantially the same as example 1 except that graphene oxide is not subjected to rare earth modification.

The polyvinylidene fluoride-based flexible piezoelectric material is prepared from the following raw materials in parts by weight:

70 parts of polyvinylidene fluoride, 140 parts of nylon 111140 parts, 3 parts of coupling agent treated graphene oxide and polyamide-imide grafted Bi_0.5Na_0.5TiO₃-BaTiO₃10 parts of polybutylene succinate and 2 parts of polybutylene succinate.

The method for treating the graphene oxide by the coupling agent comprises the following steps:

adding acetic acid into 95% ethanol to adjust pH to 4.5, adding silane coupling agent A151, hydrolyzing for 10min, adding graphene oxide, heating to 30 deg.C, ultrasonically oscillating for 10min, taking out, and oven drying.

Comparative example 5

Comparative example 5 is substantially the same as example 1 except that Bi_0.5Na_0.5TiO₃-BaTiO₃Not grafted with polyamideimide.

The polyvinylidene fluoride-based flexible piezoelectric material is prepared from the following raw materials in parts by weight:

70 parts of polyvinylidene fluoride, 140 parts of nylon 111140 parts, 3 parts of coupling agent treated rare earth modified graphene oxide and Bi_0.5Na_0.5TiO₃-BaTiO₃10 parts of polybutylene succinate and 2 parts of polybutylene succinate.

And (3) performance testing:

the piezoelectric materials prepared in examples 1 to 5 and comparative examples 1 to 5 of the present invention were cut into 2cm × 5cm sheets, copper conductive adhesives were applied to both sides of the sheet, polyimide single-sided adhesive was further applied to the surfaces of the copper conductive adhesives, and then the sheets were packaged to obtain test samples, which were subjected to performance tests.

Piezoelectric constant d₃₃The test is carried out on a ZJ-6A piezoelectric analyzer at room temperature, the sample is polarized according to a common method before the test, and the impedance analyzer is used for testingCalculating the parameters of resonance, anti-resonance frequency, equivalent resistance and equivalent capacitance at 1kHz and the like of the sample at room temperature, and calculating the planar electromechanical coupling coefficient K of the sample_pAnd a dielectric loss tan δ.

The tensile strength and the elongation at break of the material are tested by a strength tester, the material is set to be stretched in the radial direction, the gauge length is 30mm, the stretching speed is 100mm/min, and the initial tracking force is 2.0N.

The results of the performance tests are shown in table 1 below:

TABLE 1

As can be seen from the above table 1, the piezoelectric material prepared by the invention has good piezoelectric performance and good flexibility, the piezoelectric constant is not less than 44.19pC/N, the planar electromechanical coupling coefficient is not less than 0.31, the dielectric loss is not more than 1.08%, the tensile strength is not less than 6.45MPa, the breaking elongation is not less than 220%, the piezoelectric performance of the material is improved while the flexibility of the polymer is maintained, and the piezoelectric material has a wide application prospect in wearable equipment.

The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.