A preparation method of synergistically doped modified polyvinylidene fluoride piezoelectric nanogenerator

Abstract

The invention discloses a preparation method of a synergistically doped modified polyvinylidene fluoride piezoelectric nanogenerator, which comprises the following steps: dissolving polyvinylidene fluoride (PVDF) in a mixed solvent of dimethylacetamide (DMAc) and acetone, and adding a certain proportion of a β-nucleating agent, a chemical modifier and inorganic nanoparticles with piezoelectric properties to prepare a uniform and stable spinning solution of a certain concentration; electrospinning the spinning solution through an electrostatic spinning machine, wherein the receiving device is a high-speed roller, to prepare an oriented nanofiber membrane; encapsulating the oriented nanofiber membrane by adding a curing agent to PDMS; vertically cutting the cured nanofiber membrane along the longitudinal direction of the nanofiber, arranging the nanofiber membrane perpendicular to the horizontal position, and combining the nanofiber membrane into an elastic and vertically arranged nanofiber piezoelectric film; attaching conductive plates on the upper and lower sides of the prepared piezoelectric film, and encapsulating the entire film with PDMS to prepare a nanogenerator.

Description

Technical Field

[0001] The invention belongs to the technical field of electrostatic spinning and relates to a method for preparing a synergistically doped modified polyvinylidene fluoride piezoelectric nanogenerator. Background Art

[0002] As an emerging component material in modern electronics, nanomaterials have a series of unique morphologies and properties, providing a broad window for improving the performance of various energy devices. The use of nanomaterials and nanotechnology to obtain energy from the environment as a sustainable and self-sufficient energy source constitutes an emerging field of nanoenergy, which can be used to provide continuous energy for electronic devices.

[0003] Commonly used polymers with strong piezoelectric properties mainly include polyvinylidene fluoride (PVDF) and its copolymers. Among them, PVDF is the most widely used piezoelectric polymer because of its good processability, acid and alkali corrosion resistance, and high mechanical strength. Electrospinning is a common method for preparing polymer-based piezoelectric nanogenerators. The strong electric field during the spinning process has a certain uniaxial stretching effect on the polymer, which can enhance the piezoelectric properties of nanofibers and nanowires.

[0004] The output efficiency of existing nanogenerators needs to be improved. The output current of friction nanogenerators is relatively small and is more affected by the environment, while the output performance of piezoelectric nanogenerators mainly depends on the piezoelectric effect of the material itself. Therefore, improving the piezoelectric effect of the material is crucial for piezoelectric nanogenerators. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing a synergistically doped modified polyvinylidene fluoride piezoelectric nanogenerator, which solves the problem of low piezoelectric output performance of PVDF nanofiber membranes in the prior art.

[0006] The technical solution adopted by the present invention is a method for preparing a synergistically doped modified polyvinylidene fluoride piezoelectric nanogenerator, which is specifically implemented according to the following steps:

[0007] Step 1, adding PVDF to a mixed solvent formed by DMAc and acetone, and stirring until transparent to obtain a mixed solution 1, then adding a β-nucleating agent, a chemical modifier and inorganic nanoparticles with piezoelectric properties to the mixed solution 1, stirring for 60 to 300 minutes, and obtaining a spinning solution;

[0008] Step 2, electrospinning the spinning solution obtained in step 1 to obtain a PVDF oriented nanofiber membrane;

[0009] Step 3, drying the oriented nanofiber membrane obtained in step 2, and then encapsulating it in PDMS to obtain an oriented nanofiber encapsulation membrane;

[0010] Step 4, cutting the oriented nanofiber encapsulation film obtained in step 3 into strips with a width of 0.5 to 1 mm perpendicular to the arrangement direction of the nanofibers, and arranging them in parallel perpendicular to the horizontal position to obtain a nanofiber piezoelectric film;

[0011] Step 5: stick the upper conductive plate and the lower conductive plate to the two sides of the nanofiber piezoelectric film obtained in step 4 respectively, in direct contact with the nanofiber piezoelectric film, and then use PDMS to encapsulate the conductive plate and the nanofiber piezoelectric film, wherein the exposed upper and lower electrodes of the upper and lower conductive plates are not encapsulated, to obtain a PVDF-based piezoelectric nanogenerator.

[0012] The present invention is also characterized in that:

[0013] In step 1, the volume ratio of DMAc to acetone in the mixed solvent formed by DMAc and acetone is 1-4:1.

[0014] The mass concentration of PVDF in the mixed solution 1 in step 1 is 10wt% to 18wt%.

[0015] In step 1, the β-nucleating agent is one or more of vitamin B2, sodium niobate particles, and polyurethane.

[0016] When the β-nucleating agent is vitamin B2, the mass concentration of the β-nucleating agent is 1wt% to 10wt%; when the β-nucleating agent is sodium niobate particles, the mass concentration of the β-nucleating agent is 5wt% to 12wt%; when the β-nucleating agent is polyurethane, the mass concentration of the β-nucleating agent is 4wt% to 15wt%.

[0017] The process parameters of electrospinning in step 2 are: spinning temperature of 20-35° C., relative humidity of 40-50%, infusion speed of 0.5-1.0 mL / h, spinning distance of 10-20 cm, spinning voltage of 10-25 kV, and spinning time of 2-4 h.

[0018] In step 3, encapsulating the oriented nanofiber membrane in PDMS specifically involves adding PDMS and a curing agent into a container, and then placing the oriented nanofiber membrane in the container for encapsulation.

[0019] In step 5, the conductive plate is an ITO-PET conductive plate or an FPC conductive plate.

[0020] The beneficial effects of the present invention are:

[0021] 1. The piezoelectric properties of the nanofiber membrane are synergistically improved by adding β-nucleating agents to increase the β-phase content, modifying the chemical structure, and doping with inorganic nanoparticles with piezoelectric properties;

[0022] 2. The oriented nanofiber film is collected by high-speed rollers, and a structure in which the oriented nanofibers are arranged vertically and in parallel is designed and manufactured, which greatly improves the output performance of the piezoelectric nanogenerator. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a front cross-sectional view of a polyvinylidene fluoride piezoelectric nanogenerator prepared by the method of the present invention;

[0024] Figure 2 It is a side cross-sectional view of a polyvinylidene fluoride piezoelectric nanogenerator prepared by the method of the present invention.

[0025] Among them, 1. upper electrode, 2. upper conductive plate, 3. PDMS, 4. oriented nanofiber encapsulation membrane, 5. lower conductive plate, 6. lower electrode. DETAILED DESCRIPTION

[0026] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] The present invention provides a method for preparing a synergistically doped modified polyvinylidene fluoride piezoelectric nanogenerator, which is specifically implemented according to the following steps:

[0028] Step 1, adding PVDF to a mixed solvent formed by DMAc and acetone, wherein the volume ratio of DMAc to acetone is 1-4:1, and stirring until transparent to obtain a mixed solution 1, wherein the mass concentration of PVDF in the mixed solution 1 is 10wt% to 18wt%, and then adding a β-nucleating agent, a chemical modifier, and inorganic nanoparticles with piezoelectric properties to the mixed solution 1, stirring for 60 to 300 minutes, to obtain a spinning solution;

[0029] The β-nucleating agent is one or more of vitamin B2, sodium niobate particles, and polyurethane;

[0030] When the β-nucleating agent is vitamin B2, the mass concentration of the β-nucleating agent is 1wt% to 10wt%; when the β-nucleating agent is sodium niobate particles, the mass concentration of the β-nucleating agent is 5wt% to 12wt%; when the β-nucleating agent is polyurethane, the mass concentration of the β-nucleating agent is 4wt% to 15wt%.

[0031] The chemical modifier is dopamine, and the mass concentration is 6wt% to 25wt%;

[0032] The inorganic nanoparticles are one of nano ZnO, CNTs, and BaTiO3;

[0033] When the inorganic nanoparticles are ZnO, the mass concentration of the inorganic nanoparticles is 0.5wt% to 2.0wt%; when the inorganic nanoparticles are CNTs, the mass concentration of the inorganic nanoparticles is 1.0wt% to 2.5wt%; when the inorganic nanoparticles are BaTiO3, the mass concentration of the inorganic nanoparticles is 5wt% to 21wt%;

[0034] Step 2, electrospinning the spinning solution obtained in step 1 to obtain a PVDF oriented nanofiber membrane with a β phase, wherein the receiving device in the electrospinning is a high-speed roller;

[0035] The process parameters of electrospinning are: spinning temperature of 20-35°C, relative humidity of 40-50%, perfusion speed of 0.5-1.0 mL / h, spinning distance of 10-20 cm, spinning voltage of 10-25 kV, and spinning time of 2-4 h;

[0036] Step 3, drying the oriented nanofiber membrane obtained in step 2 for 30 to 50 minutes, and then encapsulating it in PDMS to obtain an oriented nanofiber encapsulation membrane. The encapsulation process is specifically as follows: adding PDMS and a curing agent in a container at a ratio of 10:1, and then placing the oriented nanofiber membrane in the container for encapsulation;

[0037] Step 4, cutting the oriented nanofiber encapsulation film obtained in step 3 into strips with a width of 0.5 to 1 mm perpendicular to the arrangement direction of the nanofibers, and arranging them in parallel perpendicular to the horizontal position to obtain a nanofiber piezoelectric film;

[0038] Step 5, respectively attach the upper conductive plate 2 and the lower conductive plate 5 to the two sides of the nanofiber piezoelectric film obtained in step 4, in direct contact with the nanofiber piezoelectric film, and then use PDMS to encapsulate the conductive plate and the nanofiber piezoelectric film, wherein the upper electrode 1 and the lower electrode 6 exposed by the upper conductive plate 2 and the lower conductive plate 3 are not encapsulated, to obtain a PVDF-based piezoelectric nanogenerator, and the conductive plate is an ITO-PET conductive plate or an FPC conductive plate.

[0039] In the preparation method of the synergistically doped modified polyvinylidene fluoride piezoelectric nanogenerator of the present invention, the function of step 1 is to prepare a composite spinning solution;

[0040] The use of β-nucleating agent has the advantage of increasing the content of β-phase in the nanofiber membrane, which helps to improve the piezoelectric properties of the PVDF nanofiber membrane;

[0041] The advantage of using dopamine is that hydrogen bonding is formed between dopamine and PVDF molecular chains, which will induce the α phase in PVDF to transform into β phase, thereby achieving the effect of increasing the β phase;

[0042] The advantage of using inorganic nanoparticles with piezoelectric properties is that the piezoelectric composite material composed of inorganic piezoelectric nanoparticles and PVDF has the properties of both inorganic and organic piezoelectric materials, and can produce characteristics that neither phase has, thereby further improving the piezoelectric performance.

[0043] The function of step 2 is to collect the oriented nanofibers using a high-speed rotating roller so that the fibers can be fully stretched during the collection process.

[0044] The purpose of step 3 is to use PDMS encapsulation to prepare PVDF oriented nanofiber film.

[0045] The purpose of step 4 is to obtain the designed nanofiber film by cutting and recombining the arrangement of the nanofibers.

[0046] The purpose of step 5 is to assemble the various parts into the final piezoelectric nanogenerator to form the designed piezoelectric nanogenerator structure.

[0047] Example 1

[0048] PVDF with a mass fraction of 12wt% is added to a solvent with a DMAc:acetone ratio of 70:30, and stirred until the solution is transparent. Then add 1wt% of vitamin B2, 6wt% of dopamine and 0.1wt% of ZnO, and continue stirring for 120min to fully dissolve vitamin B2 in the PVDF solution to obtain a spinning solution. The above spinning solution is electrospun, and the electrospinning process parameters are: spinning temperature of 20°C, relative humidity of 40%, perfusion speed of 0.5mL / h, spinning distance of 10cm, spinning voltage of 15kV, and spinning time of 2h. The prepared nanofiber membrane is dried for 50min to evaporate the solvent as much as possible. Then PDMS and curing agent are added to a culture dish of appropriate size, and the nanofiber membrane is encapsulated in PDMS. The above-prepared nanofiber encapsulation membrane is cut into strips with a width of 0.5mm perpendicular to the arrangement direction of the nanofibers, and arranged in parallel perpendicular to the horizontal position to obtain a nanofiber piezoelectric film. The conductive plates are attached to both sides of the membrane, directly contacting the nanofiber piezoelectric film, and then the whole is encapsulated with PDMS, and the exposed interface part of the conductive plate is not encapsulated. The output performance of the piezoelectric nanogenerator is tested, and the output voltage is 10.8V.

[0049] Example 2

[0050] 14wt% PVDF was added to a solution with a DMAc:acetone ratio of 60:40 and stirred until the solution was transparent. Then 5wt% vitamin B2, 6wt% dopamine and 1wt% CNTs were added and stirred for 120min to fully dissolve vitamin B2 in the PVDF solution to obtain a spinning solution. The spinning solution was subjected to electrostatic spinning, and the electrostatic spinning process parameters were spinning temperature of 25°C, relative humidity of 45%, perfusion speed of 1.0mL / h, spinning distance of 15cm, spinning voltage of 20kV and spinning time of 3h. The obtained nanofiber membrane was dried for 40min to evaporate the solvent as much as possible. Then PDMS and curing agent were added to a culture dish of appropriate size to encapsulate the nanofiber membrane in PDMS. The prepared nanofiber encapsulation membrane was cut into strips with a width of 0.6mm perpendicular to the arrangement direction of the nanofibers, and arranged in parallel perpendicular to the horizontal position to obtain a nanofiber piezoelectric film. The conductive plates are attached to both sides of the membrane, directly contacting the nanofiber piezoelectric film, and then the whole is encapsulated with PDMS, and the exposed interface part of the conductive plate is not encapsulated. The output performance of the piezoelectric nanogenerator is tested, and the output voltage is 52.5V.

[0051] Example 3

[0052] PVDF with a mass fraction of 16wt% is added to a solution with a DMAc:acetone ratio of 50:50, and stirred until the solution is transparent. Then, sodium niobate particles with a mass fraction of 9wt%, dopamine with a mass fraction of 6wt% and BaTiO3 with a mass fraction of 5wt% are added, and the stirring is continued for 300min to fully dissolve the sodium niobate particles in the PVDF solution to obtain a spinning solution. The spinning solution is subjected to electrostatic spinning, and the electrostatic spinning process parameters are spinning temperature of 30°C, relative humidity of 50%, perfusion speed of 1.5mL / h, spinning distance of 20cm, spinning voltage of 25kV, and spinning time of 4h. The obtained nanofiber membrane is dried for 30min to evaporate the solvent as much as possible. Then PDMS and curing agent are added to a culture dish of appropriate size, and the nanofiber membrane is encapsulated in PDMS. The prepared nanofiber encapsulation membrane is cut into strips with a width of 0.7mm perpendicular to the arrangement direction of the nanofibers, and arranged in parallel perpendicular to the horizontal position to obtain a nanofiber piezoelectric film. The conductive plates are attached to both sides of the membrane, directly contacting the nanofiber piezoelectric film, and then the whole is encapsulated with PDMS, and the exposed interface part of the conductive plate is not encapsulated. The output performance of the piezoelectric nanogenerator is tested, and the output voltage is 19.6V.

[0053] Example 4

[0054] 18wt% PVDF was added to a solution with a DMAc:acetone ratio of 60:40, and stirred until the solution was transparent. Then 9wt% sodium niobate particles, 6wt% dopamine and 2wt% CNTs were added, and the stirring was continued for 300min to fully dissolve the sodium niobate particles in the PVDF solution to obtain a spinning solution. The spinning solution was subjected to electrostatic spinning, and the electrostatic spinning process parameters were spinning temperature of 30°C, relative humidity of 50%, perfusion speed of 1.5mL / h, spinning distance of 20cm, spinning voltage of 25kV, and spinning time of 4h. The obtained nanofiber membrane was dried for 30min to evaporate the solvent as much as possible. Then PDMS and curing agent were added to a culture dish of appropriate size, and the nanofiber membrane was encapsulated in PDMS. The prepared nanofiber encapsulation membrane was cut into strips with a width of 0.8mm perpendicular to the arrangement direction of the nanofibers, and arranged in parallel perpendicular to the horizontal position to obtain a nanofiber piezoelectric film. The conductive plates are attached to both sides of the membrane, directly contacting the nanofiber piezoelectric film, and then the whole is encapsulated with PDMS, and the exposed interface part of the conductive plate is not encapsulated. The output performance of the piezoelectric nanogenerator is tested, and the output voltage is 31.2V.

[0055] Example 5

[0056] Add 18wt% PVDF to a solution with a DMAc:acetone ratio of 60:40 and stir until the solution is transparent. Then add 4wt% polyurethane, 6wt% dopamine and 15wt% BaTiO3, and continue stirring for 300min to fully dissolve the sodium niobate particles in the PVDF solution to obtain a spinning solution. The spinning solution is electrospun, and the electrospinning process parameters are: spinning temperature of 30°C, relative humidity of 50%, perfusion speed of 1.5mL / h, spinning distance of 20cm, spinning voltage of 25kV, and spinning time of 4h. Dry the obtained nanofiber membrane for 30min to evaporate the solvent as much as possible. Then add PDMS and curing agent to a culture dish of appropriate size, and encapsulate the nanofiber membrane in PDMS. Cut the above-prepared nanofiber encapsulation membrane into strips with a width of 1mm perpendicular to the arrangement direction of the nanofibers, and arrange them in parallel perpendicular to the horizontal position to obtain a nanofiber piezoelectric film. The conductive plates are attached to both sides of the membrane, directly contacting the nanofiber piezoelectric film, and then the whole is encapsulated with PDMS, and the exposed interface part of the conductive plate is not encapsulated. The output performance of the piezoelectric nanogenerator is tested, and the output voltage is 25.9V.

Claims

1. A method for preparing a synergistically doped modified polyvinylidene fluoride piezoelectric nanogenerator, characterized in that: Follow the steps below to implement it: Step 1: Add PVDF to a mixed solvent formed by DMAc and acetone, and stir until transparent to obtain a mixed solution 1, and then add β The nucleating agent, the chemical modifier and the inorganic nanoparticles with piezoelectric properties are stirred for 60 to 300 minutes to obtain a spinning solution; Step 2, electrospinning the spinning solution obtained in step 1 to obtain a PVDF oriented nanofiber membrane; Step 3, drying the oriented nanofiber membrane obtained in step 2, and then encapsulating it in PDMS to obtain an oriented nanofiber encapsulation membrane; Step 4, cutting the oriented nanofiber encapsulation film obtained in step 3 into strips with a width of 0.5 to 1 mm perpendicular to the arrangement direction of the nanofibers, and arranging them in parallel perpendicular to the horizontal position to obtain a nanofiber piezoelectric film; Step 5, attaching the upper conductive plate and the lower conductive plate to the two sides of the nanofiber piezoelectric film obtained in step 4 respectively, directly contacting the nanofiber piezoelectric film, and then encapsulating the conductive plate and the nanofiber piezoelectric film with PDMS, wherein the upper electrode and the lower electrode exposed by the upper conductive plate and the lower conductive plate are not encapsulated, to obtain a PVDF-based piezoelectric nanogenerator; In the step 1, the volume ratio of DMAc to acetone in the mixed solvent formed by DMAc and acetone is 1-4:1; The process parameters of the electrospinning in step 2 are: spinning temperature of 20-35° C., relative humidity of 40-50%, infusion speed of 0.5-1.0 mL / h, spinning distance of 10-20 cm, spinning voltage of 10-25 kV, and spinning time of 2-4 h.

2. The method for preparing a synergistically doped modified polyvinylidene fluoride piezoelectric nanogenerator according to claim 1, characterized in that: The mass concentration of PVDF in the mixed solution 1 in step 1 is 10wt% to 18wt%.

3. The method for preparing a synergistically doped modified polyvinylidene fluoride piezoelectric nanogenerator according to claim 1, characterized in that: In step 1 β The nucleating agent is one or more of vitamin B2, sodium niobate particles and polyurethane.

4. The method for preparing a synergistically doped modified polyvinylidene fluoride piezoelectric nanogenerator according to claim 3, characterized in that: When the β When the nucleating agent is vitamin B2, β The mass concentration of the nucleating agent is 1wt% to 10wt%; when β When the nucleating agent is sodium niobate particles, β The mass concentration of the nucleating agent is 5wt% to 12wt%; β When the nucleating agent is polyurethane, β The mass concentration of the nucleating agent is 4wt% to 15wt%.

5. The method for preparing a synergistically doped modified polyvinylidene fluoride piezoelectric nanogenerator according to claim 1, characterized in that: The step 3 of encapsulating the oriented nanofiber membrane in PDMS specifically includes adding PDMS and a curing agent into a container, and then placing the oriented nanofiber membrane in the container for encapsulation.

6. The method for preparing a synergistically doped modified polyvinylidene fluoride piezoelectric nanogenerator according to claim 1, characterized in that: In the step 5, the conductive plate is an ITO-PET conductive plate or an FPC conductive plate.

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