High-temperature-resistant piezoelectric composite fiber as well as preparation method and application thereof

Abstract

The invention discloses a high-temperature-resistant piezoelectric composite fiber and a preparation method and application thereof, and belongs to the technical field of functional composite materials. The preparation method comprises the following steps: mixing barium titanate and dopamine for stirring reaction to obtain polydopamine modified barium titanate; the nitrogen-doped graphene quantum dots are prepared by taking graphene oxide and urea as raw materials and carrying out hydrothermal reaction; the preparation method comprises the following steps: dispersing polydopamine modified barium titanate, nitrogen-doped graphene quantum dots and polyacrylonitrile in a solvent, stirring to prepare a spinning solution, and carrying out electrostatic spinning to obtain pretreated composite nanofibers; and carrying out segmented cyclization treatment on the pretreated composite nanofiber to obtain the high-temperature-resistant piezoelectric composite fiber. The invention further discloses the high-temperature-resistant piezoelectric composite fiber prepared through the method and application of the high-temperature-resistant piezoelectric composite fiber. The high-temperature-resistant piezoelectric composite fiber solves the problems that an existing polyacrylonitrile-based composite material is poor in inorganic particle dispersity, insufficient in thermal stability and limited in piezoelectric property improvement, and is wide in application prospect.

Description

Technical Field

[0001] The present invention belongs to the technical field of functional composite materials, and in particular relates to a high-temperature resistant piezoelectric composite fiber and a preparation method and application thereof. Background Art

[0002] With the development of flexible electronic devices and high-temperature sensing technology, the industry's demand for high-performance materials is showing an unprecedented growth trend; among them, piezoelectric materials that are resistant to high temperatures and have high sensitivity have become a current research hotspot and urgent need.

[0003] Flexible electronic devices, due to their unique bendable and stretchable properties, have shown tremendous potential for application in a variety of fields, including wearable devices, smart healthcare, and flexible displays. These electronic devices often need to operate under complex environmental conditions, such as high temperatures. This places even more stringent demands on the piezoelectric materials that form the core of these devices. While traditional piezoelectric materials exhibit good piezoelectric effects at room or relatively low temperatures, their piezoelectric properties often decline sharply or even disappear when the temperature rises, significantly limiting the application of flexible electronic devices in high-temperature environments.

[0004] At the same time, high-temperature sensing technology, as an indispensable part of industrial monitoring, aerospace, and energy development, also poses dual challenges to piezoelectric materials in terms of high temperature resistance and high sensitivity. In high-temperature environments, sensors need to be able to accurately and quickly respond to changes in external pressure or mechanical stress, and convert these changes into usable electrical signals for subsequent data processing and analysis. This requires that the piezoelectric materials used must not only maintain structural stability under high-temperature conditions, but also be able to maintain or enhance their piezoelectric properties at room temperature.

[0005] Therefore, the development of high-temperature resistant and highly sensitive piezoelectric materials is not only the key to promoting the development of flexible electronic devices and high-temperature sensing technologies, but also an important foundation for realizing the application of these technologies in wider and deeper fields.

[0006] Polyacrylonitrile (PAN)-based composites have become a research hotspot due to their light weight, flexibility and processability, but the following problems still exist: during the modification process, inorganic nanoparticles are easy to agglomerate in the PAN matrix, resulting in poor dispersion, which can easily lead to uneven piezoelectric performance; at the same time, PAN is prone to chain breakage and thermal degradation at high temperatures, and its insufficient thermal stability seriously limits its application in high-temperature environments; in addition, in the preparation process of piezoelectric materials, the existing technology has very limited improvement in piezoelectric performance through simple raw material blending or single modification methods. Such methods cannot optimize the molecular chain orientation and phase transition of PAN, and it is difficult to break through the bottleneck of piezoelectric output. Summary of the Invention

[0007] The problems to be solved by the present invention are: to provide a high-temperature resistant piezoelectric composite fiber, its preparation method and application, so as to solve the problems of poor dispersion of inorganic particles, insufficient thermal stability and limited improvement of piezoelectric properties in existing polyacrylonitrile-based composite materials.

[0008] The technical solution adopted to solve its technical problems is to provide a preparation method of a high-temperature resistant piezoelectric composite fiber, including the following steps:

[0009] (1) Mix barium titanate and dopamine and carry out a stirring reaction to obtain barium titanate modified with polydopamine;

[0010] (2) Use graphene oxide and urea as raw materials to carry out a hydrothermal reaction to prepare nitrogen-doped graphene quantum dots;

[0011] (3) Disperse barium titanate modified with polydopamine, nitrogen-doped graphene quantum dots and polyacrylonitrile in a solvent, prepare a spinning solution by stirring, and then carry out electrospinning to obtain pretreated composite nanofibers;

[0012] (4) Carry out segmented cyclization treatment on the pretreated composite nanofibers to obtain the high-temperature resistant piezoelectric composite fiber.

[0013] The beneficial effects of the present invention adopting the above technical solutions are: The present invention constructs a three-dimensional stable system through the synergistic effect of barium titanate modified with polydopamine (BTO@PDA), nitrogen-doped graphene quantum dots (N-GQDs) and polyacrylonitrile (PAN), realizing the enhancement of high-temperature stability and the optimization of piezoelectric properties. The abundant carboxylic acid groups (-COOH) on the surface of N-GQDs form a directional hydrogen bond network with the amino groups (-NH2) on the surface of the barium titanate core-shell structure modified with polydopamine, realizing the charge compensation effect; at the same time, the sp 2 hybrid carbon lattice of N-GQDs produces π-π conjugation with the cyano group (-C≡N) of the PAN main chain. This multi-level synergistic effect significantly increases the absolute value of the Zeta potential of the composite system, effectively overcoming the problem of particle aggregation caused by van der Waals forces. In addition, the pretreated composite nanofibers are subjected to segmented cyclization treatment (pre-oxidation, cyclization and carbonization), and a stepped carbonization process is used to construct a composite heat-resistant system. The six-membered ring carbon skeleton of N-GQDs and the graphene-like layer formed by the carbonization of PDA form an interlocking structure, jointly enhancing the heat resistance of the fiber (thermal decomposition temperature > 400 °C); at the same time, the segmented cyclization treatment induces PAN to form a highly thermally stable fiber, combining the piezoelectric effect of BTO@PDA and the conductive network of N-GQDs, and the piezoelectric output is increased by more than 200%.

[0014] Preferably, in step (1), barium titanate is dispersed with Tris-HCl buffer solution; the mass ratio of barium titanate to dopamine is 1:0.05 - 0.2; the stirring reaction is carried out under alkaline conditions for 22 - 26 h.

[0015] More preferably, the molar concentration of the Tris-HCl buffer solution is 0.8 to 1.2 M.

[0016] More preferably, the molar concentration of the Tris-HCl buffer solution is 1 M.

[0017] More preferably, the mass ratio of barium titanate to dopamine is 1:0.1; the stirring reaction is carried out at a pH of 8.5 for 24 h.

[0018] Preferably, step (2) includes the following steps: adding graphene oxide and urea into water, ultrasonically dispersing for 20 to 40 min, and then carrying out a hydrothermal reaction to obtain nitrogen-doped graphene quantum dots.

[0019] More preferably, the mass ratio of graphene oxide to urea is 1:3 to 7; the hydrothermal reaction temperature is 150 to 200 °C, and the time is 7 to 9 h.

[0020] More preferably, the mass ratio of graphene oxide to urea is 1:5; the hydrothermal reaction temperature is 180 °C, and the time is 8 h.

[0021] Preferably, in step (3), the mass ratio of polydopamine-modified barium titanate, nitrogen-doped graphene quantum dots, and polyacrylonitrile is 0.075 to 0.125:0.001 to 0.01:1; the solvent is N,N-dimethylformamide; the dispersion is ultrasonic dispersion for 0.5 to 1.5 h; the stirring temperature is 45 to 55 °C, and the time is 10 to 14 h; the voltage for electrospinning is 16 to 18 kV, the injection speed is 1 to 1.5 mL / h, and the collector rotation speed is 1000 to 1500 rpm.

[0022] Preferably, in step (4), the segmented cyclization treatment includes the following steps: heating the pretreated composite nanofibers to 50 to 200 °C at a heating rate of 4 to 6 °C / min, and holding for 0.8 to 1.2 h; then heating to 200 to 300 °C at a heating rate of 1 to 3 °C / min, and holding for 1.8 to 2.2 h; finally heating to 300 to 450 °C at a heating rate of 1 to 2 °C / min, and holding for 0.8 to 1.2 h.

[0023] The present invention also provides a high-temperature resistant piezoelectric composite fiber prepared by the above preparation method.

[0024] The present invention also provides the application of the above high-temperature resistant piezoelectric composite fiber in the preparation of a high-temperature extreme environment monitoring system, a self-powered flexible electronic device, or a high-temperature piezoelectric sensor.

[0025] The present invention has the following beneficial effects:

[0026] (1) The high-temperature resistant piezoelectric composite fiber of the present invention significantly improves the high-temperature resistance and piezoelectric properties of the composite fiber through the synergistic effect of polydopamine-modified barium titanate, nitrogen-doped graphene quantum dots and polyacrylonitrile, combined with a staged high-temperature cyclization process, and solves the problems of poor dispersion of inorganic particles, insufficient thermal stability and limited improvement of piezoelectric properties in existing polyacrylonitrile-based composite materials;

[0027] (2) The preparation method of the present invention is simple, the raw materials are easy to obtain, and it is suitable for large-scale production;

[0028] (3) The high-temperature resistant piezoelectric composite fiber of the present invention can be used to prepare extreme environment monitoring systems, self-powered flexible electronic devices or high-temperature piezoelectric sensors, providing an important basis for the application and development of high-performance materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is the preparation flow chart of the high-temperature resistant piezoelectric composite fiber of the present invention;

[0030] Figure 2 is the SEM characterization diagram of the high-temperature resistant piezoelectric composite fiber; among them, (a) is Comparative Example 1; (b) is Example 1;

[0031] Figure 3 is the comparison diagram of the piezoelectric output voltage of the high-temperature resistant piezoelectric composite fiber;

[0032] Figure 4 is the test result diagram of the high-temperature cycle stability of the high-temperature resistant piezoelectric composite fiber;

[0033] Figure 5 is the comparison diagram of the piezoelectric output voltage and piezoelectric output attenuation rate of the high-temperature resistant piezoelectric composite fiber. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments.

[0035] Therefore, the detailed description of the embodiments of the present invention provided below is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0036] The features and performance of the present invention will be further described in detail below with reference to the embodiments.

[0037] Example 1

[0038] A preparation method of high-temperature resistant piezoelectric composite fibers, comprising the following steps:

[0039] (1) Weigh 1 g of barium titanate nanoparticles and disperse them in 100 mL of 1 M Tris-HCl buffer solution with a pH of 9. Add 0.1 g of dopamine and mix. Then adjust the pH to 8.5 by adding HCl, and carry out a stirring reaction for 24 h under alkaline conditions. Dopamine spontaneously oxidizes and polymerizes on the surface of barium titanate. After centrifugation, washing, and drying, barium titanate modified with polydopamine is obtained.

[0040] (2) Add 0.1 g of graphene oxide and 0.5 g of urea to 50 mL of deionized water and ultrasonically disperse for 30 min to obtain a mixed solution. Then transfer the mixed solution to a high-pressure reaction kettle with a polytetrafluoroethylene inner lining, seal it, and place it in an oven. Carry out a hydrothermal reaction at 180 °C for 8 h. After the reaction is completed, naturally cool to room temperature, centrifuge at 8000 rpm for 15 min to collect the supernatant, and then dialyze through a dialysis bag with a molecular weight cut-off of 1000 Da for 24 h. After freeze-drying, nitrogen-doped graphene quantum dots are obtained.

[0041] (3) Mix 0.1 g of barium titanate modified with polydopamine, 0.005 g of nitrogen-doped graphene quantum dots, and 1 g of polyacrylonitrile. Then add 10 mL of N,N-dimethylformamide, ultrasonically disperse for 1 h, and then stir at 50 °C for 12 h to obtain a spinning solution. Inject the spinning solution into an electrospinning device, set the voltage to 16 kV, carry out electrospinning at an injection speed of 1.2 mL / h, the collector rotation speed is 1200 rpm, and the needle distance is 15 cm to obtain pretreated composite nanofibers.

[0042] (4) Heat the pretreated composite nanofibers to 200 °C at a heating rate of 5 °C / min and hold for 1 h. Then heat to 300 °C at a heating rate of 2 °C / min and hold for 2 h. Finally, heat to 450 °C at a heating rate of 1 °C / min and hold for 1 h to obtain high-temperature resistant piezoelectric composite fibers, denoted as BTO@PDA / N-GQDs / PAN.

[0043] The preparation process of the high-temperature resistant piezoelectric composite fibers is as Figure 1 shown.

[0044] Example 2

[0045] A preparation method of high-temperature resistant piezoelectric composite fibers, compared with the preparation method of the high-temperature resistant piezoelectric composite fibers in Example 1, is different in that: in step (3), the addition amount of barium titanate modified with polydopamine is 0.075 g, and the addition amount of nitrogen-doped graphene quantum dots is 0.01 g; the other steps and parameters are the same as those in Example 1.

[0046] Example 3

[0047] A preparation method of high-temperature resistant piezoelectric composite fibers, compared with the preparation method of the high-temperature resistant piezoelectric composite fibers in Example 1, is different in that: in step (3), the addition amount of polydopamine-modified barium titanate is 0.125 g, and the addition amount of nitrogen-doped graphene quantum dots is 0.001 g; the remaining steps and parameters are the same as those in Example 1.

[0048] Example 4

[0049] A preparation method of high-temperature resistant piezoelectric composite fibers includes the following steps:

[0050] (1) Weigh 1 g of barium titanate nanoparticles and disperse them in 100 mL of 1 M Tris-HCl buffer solution with a pH of 9. Add 0.05 g of dopamine and mix. Then add HCl to adjust the pH to 8, and carry out a stirring reaction for 26 h under alkaline conditions. Dopamine spontaneously oxidizes and polymerizes on the surface of barium titanate. After centrifugation, washing, and drying, polydopamine-modified barium titanate is obtained.

[0051] (2) Add 0.1 g of graphene oxide and 0.3 g of urea to 50 mL of deionized water and ultrasonically disperse for 20 min to obtain a mixed solution. Then transfer the mixed solution to a high-pressure reaction kettle with a polytetrafluoroethylene inner liner, seal it, and place it in an oven. Carry out a hydrothermal reaction at 150 °C for 7 h. After the reaction is completed, naturally cool to room temperature, centrifuge at 8000 rpm for 15 min to collect the supernatant, and then dialyze through a dialysis bag with a molecular weight cut-off of 1000 Da for 24 h. After freeze-drying, nitrogen-doped graphene quantum dots are obtained.

[0052] (3) Mix 0.1 g of polydopamine-modified barium titanate, 0.005 g of nitrogen-doped graphene quantum dots, and 1 g of polyacrylonitrile, and then add 10 mL of N,N-dimethylformamide. Ultrasonically disperse for 0.5 h and then stir at 45 °C for 10 h to obtain a spinning solution. Inject the spinning solution into an electrospinning device, set the voltage to 16 kV, carry out electrospinning at an injection speed of 1 mL / h, the collector rotation speed is 1000 rpm, and the needle distance is 15 cm to obtain pretreated composite nanofibers.

[0053] (4) Heat the pretreated composite nanofibers to 200 °C at a heating rate of 4 °C / min and hold for 0.8 h; then heat to 300 °C at a heating rate of 1 °C / min and hold for 1.8 h; finally, heat to 450 °C at a heating rate of 1 °C / min and hold for 0.8 h to obtain high-temperature resistant piezoelectric composite fibers.

[0054] Example 5

[0055] A preparation method of high-temperature resistant piezoelectric composite fibers includes the following steps:

[0056] (1) Weigh 1 g of barium titanate nanoparticles and disperse them in 100 mL of 1 M Tris-HCl buffer with a pH of 9. Add 0.2 g of dopamine and mix. Stir and react for 22 h under alkaline conditions. Dopamine spontaneously oxidizes and polymerizes on the surface of barium titanate. After centrifugation, washing, and drying, polydopamine-modified barium titanate is obtained.

[0057] (2) Add 0.1 g of graphene oxide and 0.7 g of urea to 50 mL of deionized water and ultrasonically disperse for 40 min to obtain a mixed solution. Then transfer the mixed solution to a polytetrafluoroethylene-lined autoclave, seal it, and place it in an oven. Carry out a hydrothermal reaction at 200 °C for 9 h. After the reaction is completed, naturally cool to room temperature. Centrifuge at 8000 rpm for 15 min to collect the supernatant, and then dialyze through a dialysis bag with a molecular weight cut-off of 1000 Da for 24 h. Freeze-dry to obtain nitrogen-doped graphene quantum dots.

[0058] (3) Mix 0.1 g of polydopamine-modified barium titanate, 0.005 g of nitrogen-doped graphene quantum dots, and 1 g of polyacrylonitrile. Then add 10 mL of N,N-dimethylformamide, ultrasonically disperse for 1.5 h, and then stir at 55 °C for 14 h to obtain a spinning solution. Inject the spinning solution into an electrospinning device, set the voltage to 18 kV, carry out electrospinning at an injection speed of 1.5 mL / h, with the collector rotation speed of 1500 rpm and the needle distance of 15 cm to obtain pretreated composite nanofibers.

[0059] (4) Heat the pretreated composite nanofibers to 200 °C at a heating rate of 6 °C / min and hold for 1.2 h. Then heat to 300 °C at a heating rate of 3 °C / min and hold for 2.2 h. Finally, heat to 450 °C at a heating rate of 2 °C / min and hold for 1.2 h to obtain high-temperature resistant piezoelectric composite fibers.

[0060] Comparative Example 1

[0061] A preparation method of high-temperature resistant piezoelectric composite fibers, comprising the following steps:

[0062] (1) Weigh 1 g of barium titanate nanoparticles and disperse them in 100 mL of 1 M Tris-HCl buffer with a pH of 9. Add 0.1 g of dopamine and mix. Then add HCl to adjust the pH to 8.5, and stir and react for 24 h under alkaline conditions. Dopamine spontaneously oxidizes and polymerizes on the surface of barium titanate. After centrifugation, washing, and drying, polydopamine-modified barium titanate is obtained.

[0063] (2) Mix 0.125 g of polydopamine-modified barium titanate and 1 g of polyacrylonitrile, then add 10 mL of N,N-dimethylformamide thereto, ultrasonically disperse for 1 h, and then stir at 50 °C for 12 h to obtain a spinning solution; Inject the spinning solution into an electrospinning device, set the voltage to 16 kV, perform electrospinning at an injection rate of 1.2 mL / h, the collector rotation speed is 1200 rpm, and the needle distance is 15 cm to obtain pretreated composite nanofibers;

[0064] (3) Heat the pretreated composite nanofibers to 200 °C at a heating rate of 5 °C / min and hold for 1 h; Then heat to 300 °C at a heating rate of 2 °C / min and hold for 2 h; Finally, heat to 450 °C at a heating rate of 1 °C / min and hold for 1 h to obtain high-temperature resistant piezoelectric composite fibers, denoted as BTO@PDA / PAN.

[0065] Comparative Example 2

[0066] A preparation method of high-temperature resistant piezoelectric composite fibers, comprising the following steps:

[0067] (1) Add 0.1 g of graphene oxide and 0.5 g of urea to 50 mL of deionized water and ultrasonically disperse for 30 min to obtain a mixed solution; Then transfer the mixed solution to a high-pressure reaction kettle with a polytetrafluoroethylene liner, seal it and place it in an oven, carry out a hydrothermal reaction at 180 °C for 8 h, naturally cool to room temperature after the reaction, centrifuge at 8000 rpm for 15 min to collect the supernatant, and then dialyze through a dialysis bag with a molecular weight cut-off of 1000 Da for 24 h, and freeze-dry to obtain nitrogen-doped graphene quantum dots;

[0068] (2) Mix 0.01 g of nitrogen-doped graphene quantum dots and 1 g of polyacrylonitrile, then add 10 mL of N,N-dimethylformamide thereto, ultrasonically disperse for 1 h, and then stir at 50 °C for 12 h to obtain a spinning solution; Inject the spinning solution into an electrospinning device, set the voltage to 16 kV, perform electrospinning at an injection rate of 1.2 mL / h, the collector rotation speed is 1200 rpm, and the needle distance is 15 cm to obtain pretreated composite nanofibers;

[0069] (3) Heat the pretreated composite nanofibers to 200 °C at a heating rate of 5 °C / min and hold for 1 h; Then heat to 300 °C at a heating rate of 2 °C / min and hold for 2 h; Finally, heat to 450 °C at a heating rate of 1 °C / min and hold for 1 h to obtain high-temperature resistant piezoelectric composite fibers, denoted as N-GQDs / PAN.

[0070] Comparative Example 3

[0071] A preparation method of high-temperature resistant piezoelectric composite fibers, comprising the following steps:

[0072] (1) Add 1 g of polyacrylonitrile to 10 mL of N,N-dimethylformamide and stir at 50 °C for 12 h to obtain a spinning solution. Inject the spinning solution into an electrospinning device, set the voltage to 16 kV, perform electrospinning at an injection rate of 1.2 mL / h, with the collector rotation speed of 1200 rpm and the needle distance of 15 cm to obtain pretreated composite nanofibers.

[0073] (2) Heat the pretreated composite nanofibers to 200 °C at a heating rate of 5 °C / min and hold for 1 h. Then heat to 300 °C at a heating rate of 2 °C / min and hold for 2 h. Finally, heat to 450 °C at a heating rate of 1 °C / min and hold for 1 h to obtain high-temperature resistant piezoelectric composite fibers, denoted as Pure PAN.

[0074] Experimental Example

[0075] 1. Morphology analysis

[0076] Perform SEM characterization on the morphology of the high-temperature resistant piezoelectric composite fibers BTO@PDA / N-GQDs / PAN prepared in Example 1 and the high-temperature resistant piezoelectric composite fibers BTO@PDA / PAN prepared in Comparative Example 1. The results are as Figure 2 shown. It can be seen from Figure 2 Figure (a) that there is a certain degree of agglomeration in the distribution of the internal fillers of the composite fibers (BTO@PDA / PAN) prepared in Comparative Example 1 (indicated by the white circles), while Figure (b) shows that the distribution of BTO particles inside the composite fibers (BTO@PDA / N-GQDs / PAN) prepared in Example 1 is more uniform and there is no obvious agglomeration phenomenon; indicating that the introduction of N-GQDs effectively improves the dispersion of BTO particles, thus contributing to improving the overall performance of the composite material.

[0077] 2. Performance test

[0078] The high-temperature resistant piezoelectric composite fibers prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were subjected to performance tests. The specific operation steps were as follows: The prepared high-temperature resistant piezoelectric composite fibers were assembled into sensors. Silver electrodes were deposited on the upper and lower surfaces of the nano-composite film by magnetron sputtering. After fixing the Cu wire with silver paste, the outer layer was encapsulated with a high-temperature resistant polyimide (PI) film. A linear motor (LinMot H01-23×86 / 160) equipped with a force probe (M7-50, Mark-10) was used to apply a periodic pressure, and the real-time pressure was monitored through a force sensor. A Keithley 6517 electrometer was used to measure the open-circuit voltage, and the response of the piezoelectric output with respect to the change in pressure was recorded. The assembled sensor was placed on a heating table, and the temperature was set to 400 °C to ensure uniform heating of the sample. In a high-temperature environment, a periodic pressure of 150 kPa was applied at a frequency of 2 Hz using a linear motor to simulate the long-term working state. After the test, the attenuation of the piezoelectric output was calculated. Among them, the calculation formula for the relative attenuation rate (R) is shown in the following formula (1); the results are as Figures 3 - 5 shown.

[0079] R = (Voc2 - Voc1) / Voc1 × 100% (1)

[0080] In the formula, Voc1 is the initial open-circuit voltage, and Voc2 is the open-circuit voltage after continuous operation for 2 h.

[0081] From Figure 3 it can be seen that the piezoelectric output voltages of Examples 1 to 3 and Comparative Examples 1 to 3 in the present invention are 6.1 V, 5.6 V, 5.7 V, 4.2 V, 3.8 V, and 2.1 V respectively. It can be seen that the high-temperature resistant piezoelectric composite fibers prepared in the present invention have good piezoelectric properties; from Figure 4 it can be known that the high-temperature resistant piezoelectric composite fibers prepared in the present invention can maintain good cyclic stability at a temperature of 400 °C; from Figure 5 it can be seen that the voltage output attenuation rates of the high-temperature resistant piezoelectric composite fibers BTO@PDA / PAN and the high-temperature resistant piezoelectric composite fibers N-GQDs / PAN prepared in the comparative examples are relatively large after working at 400 °C for 2 h, and the piezoelectric output attenuation rates are both > 30%. However, the attenuation performance of the high-temperature resistant piezoelectric composite fibers prepared in the examples of the present invention is significantly better than that of the high-temperature resistant piezoelectric composite fibers in the comparative examples, and the piezoelectric output attenuation rate < 5%.

[0082] ​

Claims

1. A preparation method of a high-temperature resistant piezoelectric composite fiber, characterized in that, It includes the following steps: (1) Mix barium titanate and dopamine and carry out a stirring reaction to obtain polydopamine-modified barium titanate; (2) Use graphene oxide and urea as raw materials to carry out a hydrothermal reaction to prepare nitrogen-doped graphene quantum dots; (3) Disperse polydopamine-modified barium titanate, nitrogen-doped graphene quantum dots and polyacrylonitrile in a solvent, prepare a spinning solution by stirring, and then carry out electrospinning to obtain pretreated composite nanofibers; (4) Carry out segmented cyclization treatment on the pretreated composite nanofibers to obtain high-temperature resistant piezoelectric composite fibers.

2. The preparation method of the high-temperature resistant piezoelectric composite fiber according to claim 1, characterized in that, In the step (1), barium titanate is dispersed using Tris-HCl buffer solution; the mass ratio of barium titanate to dopamine is 1:0.05 - 0.2; the stirring reaction is carried out under alkaline conditions for 22 - 26 h.

3. The preparation method of the high-temperature resistant piezoelectric composite fiber according to claim 2, wherein, The mass ratio of barium titanate to dopamine is 1:0.1; the stirring reaction is carried out under the condition of pH 8.5 for 24 h.

4. The preparation method of the high-temperature resistant piezoelectric composite fiber according to claim 1, wherein, The step (2) includes the following steps: Add graphene oxide and urea to water and ultrasonically disperse for 20 - 40 min, and then carry out a hydrothermal reaction to obtain nitrogen-doped graphene quantum dots.

5. The preparation method of the high-temperature resistant piezoelectric composite fiber according to claim 4, characterized in that, The mass ratio of graphene oxide to urea is 1:3 - 7; the hydrothermal reaction temperature is 150 - 200 °C and the time is 7 - 9 h.

6. The preparation method of the high-temperature resistant piezoelectric composite fiber according to claim 5, characterized in that, The mass ratio of graphene oxide to urea is 1:5; the hydrothermal reaction temperature is 180 °C and the time is 8 h.

7. The preparation method of the high-temperature resistant piezoelectric composite fiber according to claim 1, characterized in that, In the step (3), the mass ratio of polydopamine-modified barium titanate, nitrogen-doped graphene quantum dots and polyacrylonitrile is 0.075 - 0.125:0.001 - 0.01:1; the solvent is N,N-dimethylformamide; the dispersion is ultrasonic dispersion for 0.5 - 1.5 h; the stirring temperature is 45 - 55 °C and the time is 10 - 14 h; the voltage of the electrospinning is 16 - 18 kV, the injection speed is 1 - 1.5 mL / h, and the collector rotation speed is 1000 - 1500 rpm.

8. The preparation method of the high-temperature resistant piezoelectric composite fiber according to claim 1, wherein, In the step (4), the segmented cyclization treatment includes the following steps: Heat the pretreated composite nanofibers to 50 - 200 °C at a heating rate of 4 - 6 °C / min and keep warm for 0.8 - 1.2 h; then heat to 200 - 300 °C at a heating rate of 1 - 3 °C / min and keep warm for 1.8 - 2.2 h; finally heat to 300 - 450 °C at a heating rate of 1 - 2 °C / min and keep warm for 0.8 - 1.2 h.

9. A high-temperature resistant piezoelectric composite fiber prepared by the preparation method according to any one of claims 1 - 8.

10. Use of the high-temperature resistant piezoelectric composite fiber according to claim 9 in the preparation of a high-temperature extreme environment monitoring system, a self-powered flexible electronic device or a high-temperature piezoelectric sensor.

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