Polyvinylidene fluoride-based nanocomposite dielectric material and preparation method thereof

Abstract

This invention discloses a polyvinylidene fluoride (PVDF) nanocomposite dielectric material and its preparation method, relating to the field of nanocomposite material preparation. The method includes the following steps: surface modification of MXene powder with polysilazane to obtain PSZ@MXene; ceramicization treatment of the polysilazane on the PSZ@MXene surface to obtain ceramicized PSZ@MXene powder; treatment of the ceramicized PSZ@MXene powder with a surfactant to obtain surfactant-modified PSZ@MXene; and further treatment of the ceramicized PSZ@MXene powder with a surfactant to obtain surfactant-modified PSZ@MXene. The nanocomposite dielectric material obtained by this invention exhibits high dielectric constant, low loss, and stretchability, and is expected to be applied in flexible wearable electronics, energy, and environmental fields.

Description

Technical Field

[0001] This invention relates to the field of nanocomposite material preparation, and in particular to a polyvinylidene fluoride nanocomposite dielectric material and its preparation method. Background Technology

[0002] As electronic devices evolve towards smaller size and higher efficiency, the demand for polymer films with high dielectric constant (ε) and low dielectric loss (tanδ) is increasing. Compared to ceramic dielectrics, polymer dielectrics offer intrinsic advantages such as low cost, high breakdown field strength, and excellent reliability. Among them, polyvinylidene fluoride (PVDF)-based ferroelectric polymers, which generate high polarization based on carbon-fluorine bonds, are a promising class of high-energy-density dielectric materials. However, the dielectric constants of these ferroelectric polymer dielectrics are generally low (ε < 10), limiting energy storage density and making it difficult to meet the demands of modern electronic technology for rapid charge and discharge capabilities. To overcome this limitation, researchers have attempted to combine ferroelectric polymers with conductive inorganic nanofillers to improve the dielectric properties of the materials.

[0003] MXenes, or two-dimensional transition metal carbides, carbonitrides, or carbonitrides, are a general term for novel layered two-dimensional crystalline materials similar to graphene. Generally, MAX (where M = transition metal, A = aluminum or silicon, X = C, N, or CN) can be chemically etched into the A phase followed by liquid-phase exfoliation to obtain monolayer or few-layer MXenes. Due to the use of etching reagents (such as hydrofluoric acid or its fluorine-containing substitutes), the surface of MXenes often possesses abundant polar functional groups such as -OH, -F, and -O, resulting in good dispersibility in water. Therefore, MXenes not only exhibit extremely high metallic conductivity but also good hydrophilicity, showing broad application prospects in biomedicine, energy storage, catalysis, and flexible electronics. However, due to the metallic electronic structure and excessive polar groups on the surface of MXenes, they exhibit high dielectric constant and high loss in dielectric polymer composites. Therefore, MXenes require surface modification to reduce dielectric loss while maintaining a high dielectric constant.

[0004] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a dielectric material based on polyvinylidene fluoride nanocomposite and its preparation method, aiming to solve the problem of high dielectric loss of existing MXenes.

[0006] The technical solution of the present invention is as follows:

[0007] The first aspect of this invention provides a method for preparing a polyvinylidene fluoride (PVDF) nanocomposite dielectric material, comprising the following steps:

[0008] S1. MXene powder is surface-modified with polysilazane to obtain polysilazane-modified MXene, denoted as PSZ@MXene;

[0009] S2. The polysilazane on the surface of PSZ@MXene is ceramicized to obtain ceramicized PSZ@MXene powder;

[0010] S3. The ceramicized PSZ@MXene powder is treated with a surfactant to obtain surfactant-modified PSZ@MXene;

[0011] S4. Polyvinylidene fluoride and the surfactant-modified PSZ@MXene are melt-blended or solvent-blended to obtain the polyvinylidene fluoride-based nanocomposite dielectric material.

[0012] Optionally, the MXene powder is prepared by chemical exfoliation.

[0013] Optionally, the MXene powder is prepared using the following method:

[0014] MXene raw material (preferably Ti3AlC2 powder) is added to a mixed solution of lithium fluoride and concentrated hydrochloric acid, and then reacted at a temperature of 25-50°C for 16-48 hours. After centrifugation and washing, a solid precipitate is obtained.

[0015] The solid precipitate was added to ethanol and stirred for 24-48 hours (to perform ethanol intercalation), followed by centrifugation to remove the ethanol, and then sonicated in deionized water (for 60-120 minutes at a power of 500-1500W). Next, MXene colloidal solution was obtained by low-speed centrifugation (preferably 3000 rpm). Finally, MXene powder was obtained by high-speed centrifugation (preferably 10000 rpm) and drying.

[0016] Optionally, S1 includes the following steps:

[0017] MXene powder was vacuum dried at 100–110 °C for 24–48 h, and then added to a mixed solution of polysilazane and ethanol at room temperature. The mixture was stirred for 12–48 h, and then centrifuged, washed and dried to obtain PSZ@MXene.

[0018] The mass ratio of MXene to polysilazane is 1g:0.001-0.1, and the ratio of MXene to the mixed solution of polysilazane and ethanol is 1g:50ml; the centrifugation speed is 5000-10000rpm, the time is 10-30 minutes, and the centrifugation temperature is 5-10℃; the washing solvent used is one of ethanol, cyclohexane, toluene, or N,N-dimethylformamide; the drying temperature is 40-80℃, and the time is 120-600 minutes.

[0019] Optionally, S2 includes the following steps:

[0020] The PSZ@MXene was subjected to low-temperature curing to obtain low-temperature cured PSZ@MXene powder; the low-temperature cured PSZ@MXene powder was then subjected to high-temperature ceramization in an inert atmosphere to obtain ceramized PSZ@MXene powder.

[0021] Optionally, the low-temperature curing treatment is carried out at a temperature of 100–400°C for 60–180 minutes; the high-temperature ceramization treatment is carried out at a temperature of 600–1000°C for 60–180 minutes.

[0022] Preferably, the low-temperature curing treatment is carried out at a temperature of 200–300°C for 60–120 minutes; the high-temperature ceramization treatment is carried out at a temperature of 700–900°C for 60–120 minutes.

[0023] Preferably, the low-temperature curing treatment is performed at a temperature of 250°C for 90 minutes; the high-temperature ceramization treatment is performed at a temperature of 750°C for 90 minutes.

[0024] Optionally, the inert atmosphere is argon or nitrogen.

[0025] Optionally, the surfactant described in S3 is a nonionic or ionic surfactant. Preferred surfactants include polyoxyethylene-polyoxypropylene triblock copolymer (F-127), alkyl glycosides, sodium dodecylbenzenesulfonate, and disodium lauryl sulfosuccinate. Specifically, F-127 is preferred.

[0026] Optionally, S3 includes the following steps:

[0027] The ceramicized PSZ@MXene powder, surfactant, and water were sheared and mixed, and then vacuum filtered, washed, and dried.

[0028] Optionally, the mass ratio of the ceramicized PSZ@MXene powder, surfactant, and water is 1g:0.001-0.5g:500g; the shear rate is 1000-7000rpm; and the time is 60-180 minutes.

[0029] Preferably, the mass ratio of the ceramicized PSZ@MXene powder, surfactant, and water is 1g:0.02g:500g; the shear rate is 3000-6000rpm; and the time is 60-120 minutes.

[0030] Preferably, the shearing rate is 5000 rpm and the time is 90 minutes.

[0031] Optionally, the filter membrane used for vacuum filtration is a hydrophilic filter membrane with a pore size of 200 nm; the washing solvent is water; and the drying is done at room temperature.

[0032] The melting process in S4 includes the following steps:

[0033] Dry polyvinylidene fluoride and surfactant-modified PSZ@MXene were added to a mixer for melt blending, and then pressed into tablets at high temperature to obtain the polyvinylidene fluoride-based nanocomposite dielectric material.

[0034] The mass ratio of polyvinylidene fluoride to surfactant-modified PSZ@MXene is 1g:0.005-0.05g, the melt blending temperature is 180-210℃, and the time is 5-20 minutes; the tableting temperature is 180-210℃, the holding time is 5-10 minutes, and the cold pressing time is 5-10 minutes.

[0035] Preferably, the mass ratio of polyvinylidene fluoride to surfactant-modified PSZ@MXene is 1g:0.02g, the melt blending temperature is 190℃ and the time is 10 minutes; the tableting temperature is 200℃, the holding time is 8 minutes, and the cold pressing time is 8 minutes.

[0036] Solvent blending in S4 includes the following steps:

[0037] Dry polyvinylidene fluoride and surfactant-modified PSZ@MXene were added to an N,N dimethylformamide solution and stirred. The solution was then laid on a polytetrafluoroethylene mold. After the solvent evaporated and the solution was dried, the polyvinylidene fluoride-based nanocomposite dielectric material was obtained.

[0038] The mass ratio of polyvinylidene fluoride to surfactant-modified PSZ@MXene was 1g:0.005-0.05g, the stirring speed was 500-2000rpm, the temperature was 80-200℃, and the time was 6-12h; the solvent evaporation time for film laying was 6-12h, the drying time was 6-12h, and the temperature was 80-110℃.

[0039] Preferably, the mass ratio of polyvinylidene fluoride to surfactant-modified PSZ@MXene is 1g:0.02g, the stirring speed is 1000rpm, the temperature is 110℃, and the time is 10h; the solvent evaporation time for film laying is 10h, the drying time is 9h, and the temperature is 100℃.

[0040] It should be noted that the dried polyvinylidene fluoride is obtained by the following method: PVDF granules are vacuum dried at 80-110℃ for 24-48 hours.

[0041] A second aspect of the present invention provides a polyvinylidene fluoride nanocomposite dielectric material prepared by the above method.

[0042] Beneficial effects:

[0043] 1) After the PSZ@MXene is ceramicized, the polar groups on the surface of MXene disappear, and the PSZ is ceramicized into Si-NM bonds (M is the metal on MXene) and forms a dense protective film, which can improve the dielectric constant and reduce its dielectric loss.

[0044] 2) Due to the presence of the PSZ ceramic layer, MXene can maintain low macroscopic conductivity at high content, improve the penetration threshold, and reduce high dielectric loss due to the presence of conductive network.

[0045] 3) Surfactant-modified PSZ@MXene: Due to the presence of surfactant, PSZ@MXene has a strong interaction with the CF chemical bonds in polyvinylidene fluoride (fluorine-containing crystalline polymer), which can significantly induce the formation of polar crystals in polyvinylidene fluoride; in addition, this strong interaction can also improve the dispersibility of PSZ@MXene in the matrix.

[0046] In summary, the nanocomposite dielectric material obtained by this invention not only has a high dielectric constant, but also low loss and stretchability.

[0047] The polyvinylidene fluoride / PSZ@MXene nanocomposite material of the present invention, with its high dielectric constant, low loss and stretchability, is expected to be applied in the fields of flexible wearable electronics, energy and environment. Attached Figure Description

[0048] Figure 1 A flowchart illustrating the process of preparing polyvinylidene fluoride-based nanocomposite dielectric materials according to an embodiment of the present invention. Detailed Implementation

[0049] This invention provides a dielectric material based on polyvinylidene fluoride (PVDF) nanocomposite and its preparation method. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0050] This embodiment provides a method for preparing a polyvinylidene fluoride (PVDF) nanocomposite dielectric material, such as... Figure 1 As shown, it includes the following steps:

[0051] S1. MXene powder is surface-modified with polysilazane to obtain polysilazane-modified MXene, denoted as PSZ@MXene;

[0052] S2. The polysilazane on the surface of PSZ@MXene is ceramicized to obtain ceramicized PSZ@MXene powder;

[0053] S3. The ceramicized PSZ@MXene powder is treated with a surfactant to obtain surfactant-modified PSZ@MXene;

[0054] S4. Polyvinylidene fluoride and the surfactant-modified PSZ@MXene are melt-blended or solvent-blended to obtain the polyvinylidene fluoride-based nanocomposite dielectric material.

[0055] In this embodiment, PSZ@MXene is ceramicized to obtain ceramicized PSZ@MXene powder. This step eliminates the polar groups on the MXene surface and ceramicizes PSZ into Si-NM bonds (M being the metal on the MXene), forming a dense protective film. This improves the dielectric constant while reducing its dielectric loss. The surfactant-modified PSZ@MXene exhibits strong interactions with the CF chemical bonds in polyvinylidene fluoride (PVDF, which can also be a copolymer of PVDF) due to the presence of the surfactant, significantly inducing the formation of polar PVDF crystals. Furthermore, this strong interaction also improves the dispersibility of PSZ@MXene in the matrix. Therefore, the nanocomposite dielectric material obtained in this embodiment not only possesses a high dielectric constant but also exhibits low loss and stretchability.

[0056] In one embodiment, the MXene powder is prepared by chemical exfoliation.

[0057] In some embodiments, the MXene powder is specifically prepared using the following method:

[0058] MXene raw material (preferably Ti3AlC2 powder) was added to a mixed solution of 2g lithium fluoride and 40mL concentrated hydrochloric acid (9M), and then reacted at 25-50℃ for 16-48 hours. After centrifugation and washing, a solid precipitate was obtained.

[0059] The solid precipitate was added to ethanol and stirred for 24-48 hours (to perform ethanol intercalation), then centrifuged to remove the ethanol, and then sonicated in deionized water (for 60-120 minutes at a power of 500-1500W); then centrifuged at a low speed (preferably 3000 rpm) to obtain an MXene colloidal solution; finally, centrifuged at a high speed (preferably 10000 rpm) and dried to obtain MXene powder.

[0060] Polysilazane (PSZ) is a polymer with Si-N bonds as its main chain. Due to its unique structure, it is classified into inorganic and organic polysilazanes. Si-N bonds are more readily transformed into other types of bonds than Si-O and Si-Cl bonds because their bond energy is relatively low, around 355 kJ / mol. PSZ also contains Si-N, Si-H, and NH bonds, all of which readily react with other substances such as water, alcohols, silanols, phenols, and substances containing certain functional groups. These reactions mainly include hydrolysis / alcoholization, condensation coupling, and hydrosilylation. Therefore, PSZ exhibits high chemical reactivity, making it suitable as a surface modifier for modifying inorganic nanomaterials.

[0061] In some implementations, S1 includes the following steps:

[0062] MXene powder was vacuum dried at 100–110 °C for 24–48 h, and then added to a mixed solution of polysilazane and ethanol at room temperature. The mixture was stirred for 12–48 h, and then centrifuged, washed and dried to obtain PSZ@MXene.

[0063] The mass ratio of MXene to polysilazane is 1g:0.001-0.1g, and the ratio of MXene to the mixed solution of polysilazane and ethanol is 1g:50ml; the centrifugation speed is 5000-10000rpm, the time is 10-30 minutes, and the centrifugation temperature is 5-10℃; the washing solvent used is one or a mixture of ethanol, cyclohexane, toluene, or N,N-dimethylformamide; the drying temperature is 40-80℃, and the time is 120-600 minutes.

[0064] In some implementations, S2 includes the following steps:

[0065] The PSZ@MXene powder is subjected to low-temperature curing treatment at a temperature of 100-400℃ (preferably 200-300℃, more preferably 250℃) for 60-180 minutes (preferably 60-120 minutes, more preferably 90 minutes) to obtain low-temperature cured PSZ@MXene powder;

[0066] Then, the PSZ@MXene powder that has been cured at low temperature is subjected to high-temperature ceramicization under an inert atmosphere to obtain ceramicized PSZ@MXene powder; the high-temperature ceramicization temperature is 600-1000℃ (preferably 700-900℃, more preferably 750℃), and the time is 60-180 minutes (preferably 60-120 minutes, more preferably 90 minutes).

[0067] In some embodiments, the inert atmosphere is argon or nitrogen.

[0068] In some embodiments, the surfactant described in S3 is a nonionic or ionic surfactant. Preferably, it is a polyoxyethylene-polyoxypropylene triblock copolymer (F-127), alkyl glycoside, sodium dodecylbenzenesulfonate, disodium lauryl sulfosuccinate, etc.; specifically, F-127 is preferred.

[0069] In some implementations, S3 includes the following steps:

[0070] The ceramicized PSZ@MXene powder, surfactant, and water are shear-mixed in a mass ratio of 1g:0.001-0.5g:500g (preferably 1g:0.02g:500g) at a shear rate of 1000-7000rpm (preferably 3000-6000rpm, more preferably 5000rpm) for 60-180 minutes (preferably 60-120 minutes, more preferably 90 minutes).

[0071] Then, vacuum filtration, washing, and drying are performed.

[0072] In some embodiments, the filter membrane used for vacuum filtration is a hydrophilic filter membrane with a pore size of 200 nm; the washing solvent is water; and the drying is performed at room temperature.

[0073] In some embodiments, the melting in S4 includes the following steps:

[0074] Dry polyvinylidene fluoride and surfactant-modified PSZ@MXene are added to an internal mixer for melt blending, followed by high-temperature pressing to obtain the polyvinylidene fluoride-based nanocomposite dielectric material. The melt blending temperature is 180–210°C (preferably 190°C), and the time is 5–20 minutes (preferably 10 minutes). The pressing temperature is 180–210°C (preferably 200°C), the holding time is 5–10 minutes (preferably 8 minutes), and the cold pressing time is 5–10 minutes (preferably 8 minutes).

[0075] In some embodiments, solvent blending in S4 includes the following steps:

[0076] Dry polyvinylidene fluoride (PVDF) and surfactant-modified PSZ@MXene were added to an N,N-dimethylformamide solution and stirred. The solution was then deposited onto a polytetrafluoroethylene (PTFE) mold. After the solvent evaporated and the mixture was dried, the PVDF-based nanocomposite dielectric material was obtained. The stirring speed was 500–2000 rpm (preferably 1000 rpm), the temperature was 80–200°C (preferably 110°C), and the time was 6–12 h (preferably 10 h). The solvent evaporation time was 6–12 h (preferably 10 h), the drying time was 6–12 h (preferably 9 h), and the temperature was 80–110°C (preferably 100°C).

[0077] The mass ratio of polyvinylidene fluoride to surfactant-modified PSZ@MXene is 1g:0.005-0.05g, preferably 1g:0.02g.

[0078] It should be noted that the dried polyvinylidene fluoride is obtained by the following method: vacuum drying the PVDF granules at 80-110℃ for 24-48 hours.

[0079] This embodiment also provides a polyvinylidene fluoride nanocomposite dielectric material, which is prepared by the above method.

[0080] The present invention will be further analyzed below with reference to specific embodiments.

[0081] Example 1

[0082] A method for preparing a polyvinylidene fluoride (PVDF)-based vinyl nanocomposite dielectric material includes the following steps:

[0083] S1. MXene powder is surface modified with polysilazane to obtain polysilazane-modified MXene, denoted as PSZ@MXene.

[0084] The specific steps are as follows:

[0085] MXene powder was vacuum dried at 100°C for 24 hours, and then added to a mixed solution of polysilazane and ethanol at room temperature. The mixture was stirred and mixed for 20 hours, and then centrifuged, washed and dried to obtain PSZ@MXene.

[0086] The mass ratio of MXene to polysilazane was 1g:0.01g, and the ratio of MXene to the mixed solution of polysilazane and ethanol was 1g:50ml; the centrifugation speed was 7000rpm, the time was 25 minutes, and the centrifugation temperature was 5℃; the washing solvent used was ethanol; and the drying temperature was 60℃ and the time was 150 minutes.

[0087] The preparation method of the MXene powder is as follows:

[0088] 1g of Ti3AlC2 powder was slowly added to a pre-prepared mixed solution of lithium fluoride and concentrated hydrochloric acid. The reaction was carried out for 20 hours at 45℃. After the reaction was completed, the mixed solution was centrifuged and washed to obtain a solid precipitate until the centrifuged liquid was neutral or close to neutral.

[0089] The precipitate obtained previously was intercalated with ethanol, followed by ultrasonic exfoliation in deionized water; then, an MXene colloidal solution was obtained by low-speed centrifugation; and MXene solid powder was obtained by high-speed centrifugation and drying for later use.

[0090] S2. The polysilazane on the surface of PSZ@MXene is ceramicized to obtain ceramicized PSZ@MXene powder.

[0091] The PSZ@MXene was subjected to a low-temperature curing treatment at 250°C for 90 minutes to obtain low-temperature cured PSZ@MXene powder.

[0092] The low-temperature cured PSZ@MXene powder was then subjected to high-temperature ceramization in an inert atmosphere to obtain ceramized PSZ@MXene powder; the high-temperature ceramization temperature was 750°C and the time was 90 minutes. The inert atmosphere was argon, but nitrogen could also be used.

[0093] S3. The ceramicized PSZ@MXene powder is treated with a surfactant to obtain surfactant-modified PSZ@MXene.

[0094] The ceramicized PSZ@MXene powder, surfactant (F-127), and water in a mass ratio of 1g:0.02g:500g were shear-mixed at a shear rate of 5000rpm for 90 minutes.

[0095] Then, vacuum filtration, washing, and drying are performed.

[0096] The filter membrane used for vacuum filtration is a hydrophilic membrane with a pore size of 200 nm; the washing solvent is water; and the drying is carried out at room temperature.

[0097] S4. Polyvinylidene fluoride (PVDF) and the surfactant-modified PSZ@MXene are melt-blended or solvent-blended to obtain the polyvinylidene fluoride-based nanocomposite dielectric material.

[0098] First, PVDF is vacuum dried at 85℃ for 30 hours. Then, it is melted.

[0099] Melting includes the following steps:

[0100] Dry polyvinylidene fluoride and surfactant-modified PSZ@MXene were added to a mixer for melt blending, and then pressed at high temperature to obtain the polyvinylidene fluoride-based nanocomposite dielectric material. The melt blending temperature was 190°C and the time was 10 minutes. The pressing temperature was 200°C, the holding time was 8 minutes, and the cold pressing time was 8 minutes.

[0101] The mass ratio of polyvinylidene fluoride to surfactant-modified PSZ@MXene is 1g:0.02g.

[0102] Example 2

[0103] Other preparation methods are the same as in Example 1, except that the mass ratio of MXene to polysilazane in S1 is 1g:0.005g.

[0104] Example 3

[0105] The preparation method is the same as in Example 1, except that the mass ratio of MXene to polysilazane in S1 is 1g:0.03g.

[0106] Example 4

[0107] The preparation method is the same as in Example 1, except that the mass ratio of ceramicized PSZ@MXene powder, surfactant (F-127) and water in S3 is 1g:0.05g:500g.

[0108] Example 5

[0109] The preparation method is the same as in Example 1, except that the mass ratio of ceramicized PSZ@MXene powder, surfactant (F-127) and water in S3 is 1g:0.1:500g.

[0110] Example 6

[0111] The preparation method is the same as in Example 1, except that the mass ratio of PVDF to surfactant-modified PSZ@MXene in S4 is 1g:0.008g.

[0112] Example 7

[0113] The preparation method is the same as in Example 1, except that the mass ratio of PVDF to surfactant-modified PSZ@MXene in S4 is 1g:0.01g.

[0114] Example 8

[0115] The preparation method is the same as in Example 1, except that the mass ratio of PVDF to surfactant-modified PSZ@MXene in S4 is 1g:0.04g.

[0116] Example 9

[0117] The preparation method is the same as in Example 1, except that the low-temperature curing temperature in S2 is 200℃.

[0118] Example 10

[0119] The preparation method is the same as in Example 1, except that the low-temperature curing temperature in S2 is 300℃.

[0120] Example 11

[0121] The preparation method is the same as in Example 1, except that the high-temperature ceramization temperature in S2 is 700℃.

[0122] Example 12

[0123] The preparation method is the same as in Example 1, except that the high-temperature ceramization temperature in S2 is 800℃.

[0124] Example 13

[0125] Other preparation methods are the same as in Example 1, except that S4 uses solvent blending, including the following steps:

[0126] Dry polyvinylidene fluoride and surfactant-modified PSZ@MXene were added to an N,N-dimethylformamide solution and stirred. The solution was then laid on a polytetrafluoroethylene mold. After the solvent evaporated and the mixture was dried, the polyvinylidene fluoride-based nanocomposite dielectric material was obtained. The stirring speed was 1000 rpm, the temperature was 110°C, and the time was 10 h. The solvent evaporation time for the film laying was 10 h, the drying time was 9 h, and the temperature was 100°C.

[0127] Comparative Example 1

[0128] Polyvinylidene fluoride (PVDF), MXene, and surfactant (F-127) were added to a mixer for melt blending, and then pressed at high temperature to obtain the polyvinylidene fluoride-based nanocomposite dielectric material. The melt blending temperature was 190°C and the time was 10 minutes. The pressing temperature was 200°C, the holding time was 8 minutes, and the cold pressing time was 8 minutes.

[0129] The mass ratio of polyvinylidene fluoride to surfactant-modified PSZ@MXene is 1g:0.02g.

[0130] The difference between this comparative example and Example 1 is that the MXene in this comparative example has been modified by S1, S2, and S3.

[0131] Comparative Example 2

[0132] The difference between this comparative example and Example 1 is that polysilazane was not used to modify the MXene surface in S1, while the other steps remain the same, including the subsequent ceramicization treatment in S2, the surfactant treatment in S3, and the melting in S4.

[0133] Comparative Example 3

[0134] The difference between this comparative example and comparative example 1 is that the mass ratio of PVDF to surfactant-modified PSZ@MXene in S4 is 1 g: 0.008 g.

[0135] Comparative Example 4

[0136] The difference between this comparative example and comparative example 1 is that the mass ratio of PVDF to surfactant-modified PSZ@MXene in S4 is 1g:0.01g.

[0137] Comparative Example 5

[0138] The difference between this comparative example and comparative example 1 is that the mass ratio of PVDF to surfactant-modified PSZ@MXene in S4 is 1 g: 0.04 g.

[0139] The dielectric properties and mechanical tensile properties (elongation at break) of the polyvinylidene fluoride nanocomposite dielectric material (a blend film) prepared in the above embodiments and comparative examples were tested; wherein, the frequency range of the dielectric properties was 10. 0 Up to 10 6 Hz, working voltage is 1V; dumbbell-shaped spline is used to test tensile properties, and its thickness is 0.3mm.

[0140] The dielectric and mechanical tensile properties obtained are shown in Table 1.

[0141] As shown in Table 1, the dielectric constant of pure PVDF (Comparative Example 1) is 12 at 100 Hz, with a corresponding dielectric loss of 0.1. However, it exhibits good flexibility, with an elongation at break of approximately 250%. Due to its high conductivity, MXene significantly improves the dielectric properties of PVDF when introduced into the system. For example, with an MXene content of 2% (Comparative Example 2), the dielectric constant of the system is 400 at 100 Hz, but the corresponding dielectric loss increases to 1.1. While excessive MXene content can further increase the dielectric constant of PVDF, its dielectric loss also increases accordingly (Comparative Example 5). This demonstrates that unmodified MXene has certain limitations in modifying the dielectric properties of PVDF. When MXene is modified by polysilazane ceramicization, the dielectric constant of the PVDF system increases while maintaining a low dielectric loss. For example, compared to Comparative Example 2, with the same MXene content, in Example 1, the dielectric constant of the system increases to 600, while the dielectric loss is only 0.08. Furthermore, increasing the polysilazane content (Example 3) resulted in a further increase in the dielectric constant, with only a slight increase in dielectric loss. This indicates that the ceramization of polysilazane on the MXene surface can synergistically improve the dielectric properties of PVDF, possibly due to the formation of Si-N-Ti chemical bonds, which alters the electronic structure of MXene. Further research shows that the temperatures during low-temperature curing and high-temperature ceramization processes can also slightly change the dielectric properties of the system, possibly due to the degree of ceramization of the polysilazane.

[0142] Table 1. Parameters and performance measurement results of the preparation methods of each embodiment and comparative example.

[0143]

[0144]

[0145] In summary, the present invention yields a nanocomposite material with the following advantages:

[0146] 1) After the PSZ@MXene is ceramicized, the polar groups on the surface of MXene disappear, and the PSZ is ceramicized into Si-NM bonds (M is the metal on MXene) and forms a dense protective film, which can improve the dielectric constant and reduce its dielectric loss.

[0147] 2) Due to the presence of the PSZ ceramic layer, MXene can maintain low macroscopic conductivity at high content, improve the penetration threshold, and reduce high dielectric loss due to the presence of conductive network.

[0148] 3) Surfactant-modified PSZ@MXene: Due to the presence of surfactant, PSZ@MXene has a strong interaction with the CF chemical bonds in polyvinylidene fluoride (fluorine-containing crystalline polymer), which can significantly induce the formation of polar crystals in polyvinylidene fluoride; in addition, this strong interaction can also improve the dispersion of PSZ@MXene in the matrix.

[0149] The polyvinylidene fluoride nanocomposite dielectric material of the present invention has the advantages of high dielectric constant, low loss and stretchability, and is expected to be applied in flexible wearable electronics, energy and environmental fields.

[0150] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for preparing a polyvinylidene fluoride (PVDF)-based vinyl nanocomposite dielectric material, characterized in that, Includes the following steps: S1. MXene powder is vacuum dried at 100-110℃ for 24-48h, and then added to a mixed solution of polysilazane and ethanol at room temperature. The mixture is stirred and mixed for 12-48h, and then centrifuged, washed and dried to obtain PSZ@MXene. The mass ratio of MXene powder to polysilazane is 1:0.001-0.

1. S2. The PSZ@MXene is subjected to low-temperature curing treatment to obtain low-temperature cured PSZ@MXene powder; the low-temperature cured PSZ@MXene powder is subjected to high-temperature ceramicization under an inert atmosphere to obtain ceramicized PSZ@MXene powder; S3. The ceramicized PSZ@MXene powder, surfactant and water are sheared and mixed, and then vacuum filtered, washed and dried. The mass ratio of the ceramicized PSZ@MXene powder, surfactant and water is 1g:0.001~0.5g:500g. S4. Polyvinylidene fluoride and the surfactant-modified PSZ@MXene are melt-blended or solvent-blended to obtain the polyvinylidene fluoride-based nanocomposite dielectric material.

2. The method for preparing a polyvinylidene fluoride nanocomposite dielectric material according to claim 1, characterized in that, In step S1, the ratio of MXene powder to the mixed solution of polysilazane and ethanol is 1g:50ml; the centrifugation speed is 5000-10000rpm, the time is 10-30 minutes, and the centrifugation temperature is 5-10℃; the drying temperature is 40-80℃, and the time is 120-600 minutes.

3. The method for preparing a polyvinylidene fluoride nanocomposite dielectric material according to claim 1, characterized in that, In step S2, the low-temperature curing temperature is 100–400℃ and the time is 60–180 minutes; the high-temperature ceramization temperature is 600–1000℃ and the time is 60–180 minutes.

4. The method for preparing a polyvinylidene fluoride nanocomposite dielectric material according to claim 1, characterized in that, In step S2, the low-temperature curing temperature is 200–300℃ and the time is 60–120 minutes; the high-temperature ceramization temperature is 700–900℃ and the time is 60–120 minutes.

5. The method for preparing a polyvinylidene fluoride nanocomposite dielectric material according to claim 1, characterized in that, In step S2, the low-temperature curing temperature is 250℃ and the time is 90 minutes; the high-temperature ceramization temperature is 750℃ and the time is 90 minutes.

6. The method for preparing a polyvinylidene fluoride nanocomposite dielectric material according to claim 1, characterized in that, The surfactants described in S3 are nonionic or ionic surfactants.

7. The method for preparing a polyvinylidene fluoride nanocomposite dielectric material according to claim 1, characterized in that, In step S3, the shearing rate is 1000–7000 rpm and the time is 60–180 minutes.

8. The method for preparing a polyvinylidene fluoride nanocomposite dielectric material according to claim 1, characterized in that, In step S3, the mass ratio of the ceramicized PSZ@MXene powder, surfactant, and water is 1g:0.02g:500g; the shear rate is 3000-6000rpm; and the time is 60-120 minutes.

9. The method for preparing a polyvinylidene fluoride nanocomposite dielectric material according to claim 1, characterized in that, In step S3, the shearing rate is 5000 rpm and the time is 90 minutes.

10. The method for preparing a polyvinylidene fluoride nanocomposite dielectric material according to claim 1, characterized in that, In step S4, melting includes the following steps: Dry polyvinylidene fluoride and surfactant-modified PSZ@MXene were added to a mixer for melt blending, and then pressed into tablets at high temperature to obtain the polyvinylidene fluoride-based nanocomposite dielectric material. The mass ratio of polyvinylidene fluoride to surfactant-modified PSZ@MXene is 1g:0.005~0.05g, the melt blending temperature is 180~210℃, and the time is 5~20 minutes; the tableting temperature is 180~210℃, the holding time is 5~10 minutes, and the cold pressing time is 5~10 minutes.

11. The method for preparing a polyvinylidene fluoride nanocomposite dielectric material according to claim 10, characterized in that, The mass ratio of polyvinylidene fluoride and surfactant-modified PSZ@MXene was 1g:0.02g. The melt blending temperature was 190℃ and the time was 10 minutes. The tableting temperature was 200℃, the holding time was 8 minutes, and the cold pressing time was 8 minutes.

12. The method for preparing a polyvinylidene fluoride nanocomposite dielectric material according to claim 1, characterized in that, In step S4, solvent blending includes the following steps: Dry polyvinylidene fluoride and surfactant-modified PSZ@MXene were added to an N,N dimethylformamide solution and stirred. The solution was then laid on a polytetrafluoroethylene mold. After the solvent evaporated and the solution was dried, the polyvinylidene fluoride-based nanocomposite dielectric material was obtained. The mass ratio of polyvinylidene fluoride to surfactant-modified PSZ@MXene was 1g:0.005-0.05g, the stirring speed was 500-2000rpm, the temperature was 80-200℃, and the time was 6-12h; the solvent evaporation time for film laying was 6-12h, the drying time was 6-12h, and the temperature was 80-110℃.

13. The method for preparing a polyvinylidene fluoride nanocomposite dielectric material according to claim 12, characterized in that, In step S4, the mass ratio of polyvinylidene fluoride to surfactant-modified PSZ@MXene was 1g:0.02g, the stirring speed was 1000rpm, the temperature was 110℃, and the time was 10h; the solvent evaporation time for film laying was 10h, the drying time was 9h, and the temperature was 100℃.

14. A dielectric material based on polyvinylidene fluoride nanocomposite, characterized in that, Prepared by the preparation method according to any one of claims 1-13.

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