A lignin-reinforced self-healing conductive elastomer, its preparation method and application

Abstract

This invention discloses a lignin-reinforced self-healing conductive elastomer, its preparation method, and its applications. The preparation method includes the following steps: mixing lipoic acid, lignin, a metal acid salt ionic liquid, and an organic crosslinking agent, followed by heat treatment to obtain the lignin-reinforced self-healing conductive elastomer; the mass ratio of lipoic acid to lignin is 1:(0.025~0.055). The lignin-reinforced self-healing conductive elastomer of this invention not only possesses good tensile strength but also exhibits excellent strain, temperature, and light-induced multimodal sensing properties. Furthermore, its electrical and tensile properties after damage also demonstrate excellent self-healing capabilities. In addition, both the polylipoic acid and lignin used in this invention are bio-based materials, avoiding the use of petroleum-based materials, making it environmentally friendly.

Description

Technical Field

[0001] This invention belongs to the field of conductive elastomers, specifically relating to a lignin-reinforced self-healing conductive elastomer, its preparation method, and its application. Background Technology

[0002] With the rapid development of flexible electronics technology, flexible electronic devices, due to their unique advantages such as light weight, portability, bendability, high flexibility, and wide applicability, are widely used in many cutting-edge fields such as wearable devices and soft robots. Flexible electronic devices mainly rely on flexible sensors to obtain important biological information from the human body or to support the biomimetic behavior of robots. Conductive elastomers (CEs), due to their combination of the high elasticity of polymers and the conductivity of conductors, are the core functional materials for flexible sensors, thus showing broad application prospects in the aforementioned fields.

[0003] Today, the applications of flexible electronic devices are becoming increasingly diverse. The complex application environments place high demands on the conductivity, sensing performance, and mechanical strength of the conductive elastomers used in these devices. On the other hand, in practical applications, conductive elastomers inevitably suffer micro-cracks or even macro-damage due to long-term, repeated mechanical deformation or external forces. This damage not only degrades their mechanical properties but also disrupts conductive pathways, affecting electrical performance and significantly shortening the device's lifespan.

[0004] To address this, numerous researchers have attempted to develop conductive elastomers with self-healing properties while maintaining their conductivity, sensing performance, and mechanical strength, enabling them to automatically restore their structure and function after damage. For example, an existing Chinese patent describes a polythioctic acid@polyacrylic acid conductive elastomer and its preparation method and application. Using polythioctic acid as the main material, combined with polyacrylate to form an interpenetrating network that combines rigidity and flexibility, the resulting conductive elastomer exhibits good strain sensitivity, high tensile strength, and superior self-healing ability. However, the polyacrylic acid used in this prior art is a typical petroleum-based synthetic polymer. Such materials have inherent drawbacks, including significant environmental pollution, non-renewable raw materials, and difficulty in degradation in the natural environment, resulting in poor environmental friendliness. Furthermore, this prior art cannot achieve multimodal sensing performance, meaning it cannot respond to multiple physical signals (strain, temperature, light, etc.), limiting its application in complex and high-end scenarios. Summary of the Invention

[0005] To address the issue that existing self-healing conductive elastomers cannot simultaneously achieve excellent multimodal sensing performance, tensile strength, and environmentally friendly raw materials, this invention provides a method for preparing a lignin-reinforced self-healing conductive elastomer. The lignin-reinforced self-healing conductive elastomer prepared by this method exhibits good strain, temperature, and light-induced multimodal sensing performance, high tensile strength, and considerable self-healing ability. Furthermore, it uses bio-based materials instead of traditional petroleum-based synthetic polymer materials, making it environmentally friendly.

[0006] Another object of the present invention is to provide a lignin-reinforced self-healing conductive elastomer.

[0007] Another object of the present invention is to provide the application of the above-mentioned lignin-reinforced self-healing conductive elastomer in the preparation of flexible sensors.

[0008] Another object of the present invention is to provide a flexible sensor.

[0009] The above-mentioned objective of the present invention is achieved through the following technical solution:

[0010] A method for preparing a lignin-reinforced self-healing conductive elastomer includes the following steps: The lignin-reinforced self-healing conductive elastomer is obtained by mixing lipoic acid, lignin, metal acid salt ionic liquid and organic crosslinking agent and then heat-treating the mixture. The mass ratio of thioctic acid to lignin is 1:(0.025~0.055).

[0011] It should be noted that: This invention incorporates lignin into thioctic acid monomers, successfully introducing lignin into a polythioctic acid network in the presence of a metal salt ionic liquid. Lignin possesses abundant oxygen-containing groups and can form numerous hydrogen bonds with the polythioctic acid network, facilitating the transport of conductive ions and thus improving the conductivity and strain sensing sensitivity of the resulting conductive elastomer. The metal salt ionic liquid can form metal coordination bonds and hydrogen bonds with the oxygen-containing functional groups in the network, successfully introducing lignin to form a more compact network, which helps increase the mechanical strength and conductivity of the conductive elastomer. Furthermore, since the conductivity of the metal salt ionic liquid is significantly affected by temperature, the conductive elastomer of this invention also exhibits excellent temperature sensing performance.

[0012] The inventors of this invention have also discovered that the introduction of lignin can enable the prepared conductive elastomer to have good photothermal properties, that is, the temperature will rise to different degrees when exposed to light of different intensities, thereby enabling the conductive elastomer to have good light sensing properties.

[0013] Preferably, the mass ratio of lipoic acid to lignin is 1:(0.028~0.032). By controlling the lipoic acid and lignin within this range, the resulting lignin-reinforced self-healing conductive elastomer exhibits higher electrical conductivity and tensile strength.

[0014] Preferably, the mass ratio of thioctic acid to organic crosslinking agent is 1:(0.3~0.4).

[0015] Preferably, before mixing, the process further includes a pretreatment step of lignin: mixing lignin with an organic solvent at 30-40°C for 1.8-3 hours, filtering to obtain the filtrate, removing the organic solvent from the filtrate, and obtaining the pretreated lignin.

[0016] Pretreatment of lignin yields lignin with smaller molecular weights, which makes it easier to introduce lignin into lignin-reinforced self-healing conductive elastomers, thereby improving the various properties of lignin-reinforced self-healing conductive elastomers.

[0017] More preferably, the organic solvent is at least one of anhydrous ethanol and ethyl acetate.

[0018] More preferably, the ratio of lignin to organic solvent is 10g:(90~150)mL.

[0019] More preferably, the step of removing the organic solvent from the filtrate is: rotary evaporation and drying.

[0020] More preferably, the rotary evaporation temperature is 40~60℃ and the time is 0.5~1.0 h.

[0021] More preferably, the drying temperature is 50~70℃ and the time is 12~24 h.

[0022] More preferably, after removing the organic solvent from the filtrate, a grinding step is also included.

[0023] Preferably, the lignin is at least one of enzymatically hydrolyzed lignin, alkali lignin, or sulfonate lignin.

[0024] More preferably, the lignin is alkali lignin; by using alkali lignin, the lignin-reinforced self-healing conductive elastomer has higher electrical conductivity.

[0025] Preferably, the metal element in the metal salt ionic liquid is at least one of Zn, Al, and Fe.

[0026] More preferably, the anion in the metal salt ionic liquid is [ZnCl3]. - [AlCl4] - [FeCl4] -At least one of them.

[0027] Preferably, the cation in the metal acid salt ionic liquid is an imidazole ion; the imidazole ion is a monosubstituted imidazole ion; specifically, it is... , , , , At least one of them.

[0028] More preferably, the metal acid salt ionic liquid is at least one of 1-butyl-3-methylimidazolium chloride and 1-butyl-3-methylimidazolium aluminum chloride.

[0029] Preferably, the mass ratio of the thioctic acid to the metal salt ionic liquid is 1:(0.25~0.45); Preferably, the organic crosslinking agent is at least one selected from polyethylene glycol diacrylate, 1,3-diisopropenylbenzene, styrene, itaconic acid, butylene glycol diacrylate, hydroxyethyl methacrylate, and acrylic acid.

[0030] Preferably, when mixing the thioctic acid, lignin, ionic liquid and organic crosslinking agent, an organic solvent is also added for mixing.

[0031] More preferably, the organic solvent is at least one of anhydrous ethanol and ethyl acetate.

[0032] More preferably, the ratio of thioctic acid to organic solvent is 1 g: (5~10) mL.

[0033] Preferably, the heat treatment temperature is 55~65℃.

[0034] Preferably, the heat treatment time is 25-35 minutes.

[0035] Preferably, the heat treatment is carried out under stirring conditions.

[0036] Preferably, the heat treatment further includes the steps of loading into a mold, shaping, and drying.

[0037] More preferably, the shaping method involves letting the sample stand for 24 to 36 hours.

[0038] More preferably, the drying temperature is 50~70°C and the time is 10~18h.

[0039] This invention also protects a lignin-reinforced self-healing conductive elastomer, prepared by the above-described method.

[0040] This invention also protects the application of the above-mentioned lignin-reinforced self-healing conductive elastomer in the preparation of flexible sensors.

[0041] The present invention also protects a flexible sensor comprising the above-described lignin-reinforced self-healing conductive elastomer.

[0042] Preferably, the flexible sensor is a sensor used in wearable devices or soft robots.

[0043] Compared with the prior art, the beneficial effects of the present invention are: This invention introduces lignin and a specific ionic liquid into polythioctic acid (PPA), and uses a specific organic crosslinking agent to enhance the stability of PPA. The resulting lignin-reinforced self-healing conductive elastomer not only has good tensile strength but also excellent multimodal sensing properties related to strain, temperature, and light. Furthermore, its electrical and tensile properties after damage exhibit excellent self-healing capabilities. In addition, both PPA and lignin used in this invention are bio-based materials, avoiding the use of petroleum-based materials, making it environmentally friendly. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the preparation process and structure of the lignin-reinforced self-healing conductive elastomer in Example 1.

[0045] Figure 2 The stress-strain curves are for the lignin-reinforced self-healing conductive elastomers of Examples 1-2 and Comparative Examples 1-2.

[0046] Figure 3 The diagram shows the process and results of the self-healing test of the lignin-reinforced self-healing conductive elastomer in Example 1.

[0047] Figure 4 The cut-and-heal cycle resistance test curve of the lignin-reinforced self-healing conductive elastomer in Example 1 is shown.

[0048] Figure 5 The resistance response-strain curve of the lignin-reinforced self-healing conductive elastomer in Example 1 is shown.

[0049] Figure 6 The figure shows the fine strain cyclic loading-unloading tensile test curve of the lignin-reinforced self-healing conductive elastomer in Example 1.

[0050] Figure 7 The large strain cyclic loading-unloading tensile test curves are for the lignin-reinforced self-healing conductive elastomer of Example 1.

[0051] Figure 8 The resistance response-temperature curve of the lignin-reinforced self-healing conductive elastomer in Example 1 is shown.

[0052] Figure 9 The resistance response-light intensity curve of the lignin-reinforced self-healing conductive elastomer in Example 1 is shown. Detailed Implementation

[0053] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in this technical field.

[0054] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.

[0055] Example 1 This embodiment provides a method for preparing a lignin-reinforced self-healing conductive elastomer, comprising the following steps: (1) Preparation of ethanol-extracted lignin: 100 mL of anhydrous ethanol was added to 10 g of alkali lignin (Shandong Longli Biotechnology Co., Ltd.), and the mixture was stirred at 400 rpm for 2 h in a 35 °C water bath. After filtration, most of the solvent was removed by rotary evaporation of the filtrate, and the filtrate was dried in an oven at 60 °C. After grinding, ethanol-extracted lignin (AOH) was obtained.

[0056] (2) Preparation of 1-butyl-3-methylimidazolium chloride ([BMIM][ZnCl3]): 20.0 g of N-methylimidazolium and 27.66 g of 1-chlorobutane were reacted at room temperature under a nitrogen atmosphere for 24 h. The mixture was washed three times with a mixture of ethyl acetate and anhydrous diethyl ether (1:1). A large amount of solvent was removed by rotary evaporator. After vacuum drying, a colorless and transparent oily liquid was obtained. The above colorless and transparent oily liquid was stirred with anhydrous ZnCl2 at a molar ratio of 1:1 at room temperature for 4 h to obtain a transparent and uniform liquid [BMIM][ZnCl3].

[0057] (3) Preparation of elastomer: 1 g of thioctic acid (TA), 0.3 g of polyethylene glycol diacrylate (PEGDA) (Shanghai Maclean Reagent Co., Ltd., molecular weight: 575), 0.3 g of [BMIM][ZnCl3] and 0.03 g of AOH were mixed with 6 mL of anhydrous ethanol. The mixture was then magnetically stirred at 400 rpm for 30 min at 60 °C. The mixture was then poured into a mold and left at room temperature for 24 h. After that, it was placed in a 60 °C oven for 12 h to obtain the lignin-reinforced self-healing conductive elastomer. The self-healing conductive polythioctic acid elastomer in this embodiment was named TOH-3 according to the amount of lignin used.

[0058] The preparation process and structural schematic diagram of the lignin-reinforced self-healing conductive elastomer in this embodiment are shown below. Figure 1 As shown.

[0059] Example 2 This embodiment provides a method for preparing a lignin-reinforced self-healing conductive elastomer. The difference from Embodiment 1 is that the amount of AOH used in step (3) is 0.05g. The lignin-reinforced self-healing conductive elastomer in this embodiment is named TOH-5 according to the amount of lignin used.

[0060] Example 3 This embodiment provides a method for preparing a lignin-reinforced self-healing conductive elastomer. The difference from Embodiment 1 is that the amount of PEGDA used in step (3) is 0.4g. The lignin-reinforced self-healing conductive elastomer in this embodiment is named PEGDA-4 based on the amount of PEGDA used.

[0061] Example 4 This embodiment provides a method for preparing a lignin-reinforced self-healing conductive elastomer. The difference from Embodiment 1 is that the amount of [BMIM][ZnCl3] used in step (3) is 0.4g. The lignin-reinforced self-healing conductive elastomer in this embodiment is named BMIM-4 according to the amount of [BMIM][ZnCl3].

[0062] Example 5 This embodiment provides a method for preparing a lignin-enhanced self-healing conductive elastomer. The difference from Embodiment 1 is that the alkali lignin in step (1) is replaced with the same mass of enzymatically hydrolyzed lignin (Shandong Longli Biotechnology Co., Ltd.).

[0063] Example 6 This embodiment provides a method for preparing a lignin-reinforced self-healing conductive elastomer. The difference from Embodiment 1 is that in step (2), anhydrous ZnCl2 is replaced with an equal mass of anhydrous AlCl3, and the resulting ionic liquid is [BMIM][AlCl4]; in step (3), [BMIM][ZnCl3] is replaced with the same mass of [BMIM][AlCl4].

[0064] Comparative Example 1 This comparative example provides a method for preparing a lignin-reinforced self-healing conductive elastomer. The difference from Example 1 is that AOH is not added in step (3). The lignin-reinforced self-healing conductive elastomer of this comparative example is named TOH-0 according to the amount of lignin used.

[0065] Comparative Example 2 This comparative example provides a method for preparing a lignin-reinforced self-healing conductive elastomer. The difference from Example 1 is that the amount of AOH used in step (3) is 0.07g. The lignin-reinforced self-healing conductive elastomer of this comparative example is named TOH-7 according to the amount of lignin used.

[0066] Comparative Example 3 This comparative example provides a method for preparing a lignin-reinforced self-healing conductive elastomer. The difference from Example 1 is that in step (3), AOH is replaced with 0.03g of itaconic acid. The lignin-reinforced self-healing conductive elastomer of this comparative example is named IA-3.

[0067] Comparative Example 4 The preparation method of the lignin-reinforced self-healing conductive elastomer in this comparative example differs from that in Example 1 in that step (2) is omitted and in step (3) [BMIM][ZnCl3] is replaced with an equal mass of ZnCl2; the lignin-reinforced self-healing conductive elastomer in this comparative example is named ZNCL-3.

[0068] Sample characterization and performance testing (1) Tensile tests were performed on the conductive elastomer samples of each embodiment and each comparative example, and the steps are as follows: Tensile tests were performed on the samples (dumbbell-shaped samples, 4 mm wide, 20 mm long, and 2 mm deep) of each embodiment and comparative example using a tensile testing machine (UTM 6103, 100 N load sensor) at room temperature.

[0069] The tensile strength-strain curves of the conductive elastomer samples in Examples 1-2 and Comparative Examples 1-2 are shown below. Figure 2 As shown, the tensile strength of the conductive elastomer samples in Examples 1 and 2 is not less than 70 kPa, and the maximum strain is not less than 1000%, indicating that the lignin-reinforced self-healing conductive elastomer of the present invention has good tensile strength properties. In Comparative Example 1, without the addition of lignin, the tensile strength of the resulting conductive elastomer is significantly poor; in Comparative Example 2, the amount of lignin is too large, resulting in poor tensile strength and maximum strain of the resulting conductive elastomer.

[0070] The tensile test results of Examples 3-6 are similar to those of Example 1.

[0071] (2) Conductivity tests were performed on the conductive elastomer samples of each embodiment and each comparative example. The steps are as follows: Samples (strip samples, 2×10×50mm) from each embodiment and comparative example were connected to the positive and negative electrodes of the electrochemical workstation, and their conductivity was tested and calculated.

[0072] The conductivity test results of the conductive elastomer samples of each embodiment and comparative example are shown in Table 1.

[0073] Table 1. Conductivity of conductive elastomer samples from each embodiment and comparative example.

[0074] It can be seen that the conductivity of the conductive elastomers in each embodiment is not less than 0.0167 S / m, indicating that the lignin-reinforced self-healing conductive elastomer of the present invention has good conductivity. Comparative Example 1 did not add lignin, Comparative Example 2 used too much lignin, Comparative Example 3 used itaconic acid instead of lignin, and Comparative Example 4 used ZnCl2 instead of [BMIM][ZnCl3] ionic liquid. The conductivity of the resulting conductive elastomers was significantly lower than that of the embodiments, indicating weak conductivity.

[0075] (3) Self-healing tests were performed on the conductive elastomer samples of each embodiment and each comparative example, which were divided into self-healing tensile tests and cut-and-heal cycle resistance tests. The steps are as follows: Self-healing tensile test: The material self-heals internally. A cut-healing experiment was conducted. The sample was completely cut in half and spliced ​​together in an oven at room temperature (25 ℃) for 24 h to self-heal. The healed sample was then stretched and the tensile strain was recorded.

[0076] Cut-off-healing cycle resistance test: Electro-healing experiments were conducted on conductive elastomers. The resistance of the samples was measured using a Keithley 2450 digital source instrument, and the relative resistance change of the material was calculated.

[0077] A photograph of the self-healing process of the TOH-3 sample in Example 1 after it was cut is shown below. Figure 3 As shown in the figure, the self-healing TOH-3 sample clearly shows a connection in the middle of the elastomer, and it can reach a strain of 350% after stretching, indicating that the elastomer has good self-healing ability in terms of its shape and mechanical properties; the cut-and-heal cycle resistance test results of the TOH-3 sample are shown in the figure. Figure 4 As shown, when the sample was cut, the resistance in the circuit suddenly increased, indicating that there was no conductive path in the cut sample. After the broken sample was re-contacted, the resistance quickly returned to the level before cutting, and this was the case for all five cut-and-heal cycles. This indicates that the conductivity of the sample can stably recover to the level before cutting after each cut-and-heal cycle, confirming the excellent self-healing ability of the sample's electrical properties. The self-healing test results of Examples 2-6 are similar to those of Example 1.

[0078] (4) Strain sensing tests were performed on the conductive elastomer samples of each embodiment, and the steps are as follows: The relative resistance and current variations of the conductive elastomer as a function of strain were recorded using a Keithley 2450 digital source instrument. The elastomer had dimensions of 30 × 10 × 1 mm. 3 This is used to assemble wearable sensors. The relative resistance change is calculated using the following formula:

[0079] Where R is the real-time resistance of the tensile elastomer in a certain state, and R0 is the original resistance.

[0080] The strain sensitivity of the elastic body is evaluated by calculating the measurement factor GF according to the formula:

[0081] The resistance response-strain curve of the TOH-3 sample in Example 1 is shown below. Figure 5 As shown, the resistance change rate ΔR / R0 of the TOH-3 sample exhibits a clear relationship with strain within the strain range of 0~1200%, indicating that the sample resistance has a sensitive response to strain; in particular, the greater the strain of the elastomer, the higher the sensitivity of the resistance to strain response. The resistance response-strain curves of Examples 2~6 are similar to those of Example 1.

[0082] (5) Perform cyclic loading-unloading tensile tests on the conductive elastomer samples of each embodiment, as follows: The relative resistance of the conductive elastomer as a function of strain was recorded using a Keithley 2450 digital source instrument. Cyclic loading-unloading tension was performed at small strains (1%, 3%, 5%, 10%) and large strains (50%, 100%, 150%), and the changes in relative resistance were recorded.

[0083] The results of the TOH-3 sample in Example 1 under cyclic loading-unloading tensile tests in fine and large tensile conditions are as follows: Figure 6 and Figure 7 As shown, the TOH-3 sample exhibits sensitive signal response and stable signal repeatability under repeated tensile stress within a strain range of 1% to 150%, indicating that the sample has excellent and stable sensing performance with high reliability. In contrast, the TOH-0 sample of Comparative Example 1, without lignin, shows lower sensing sensitivity under repeated tensile stress at higher strains (≥100%) compared to Example 1.

[0084] The results of the cyclic loading-unloading tensile tests in Examples 2-6 are similar to those in Example 1.

[0085] (6) Temperature sensing tests were performed on the conductive elastomer samples of each embodiment, and the steps are as follows: The relative resistance of conductive elastomers as a function of temperature was recorded using a Keithley 2450 digital source instrument, showing the changes in the relative resistance of AOH-3 elastomers at different temperatures.

[0086] The resistivity change rate of the TOH-3 sample in Example 1 at different temperatures is as follows: Figure 8As shown, within the temperature range of 20~70℃, the rate of change of resistance decreases significantly with each increase in temperature, while the rate of change of resistance remains stable when the temperature remains constant. This indicates that the resistance of the TOH-3 sample has a sensitive response to temperature within the above temperature range. The temperature sensing test results of Examples 2~6 are similar to those of Example 1.

[0087] (7) The conductive elastomer samples of each embodiment were subjected to light-sensing tests, and the steps are as follows: The elastomer was irradiated with light sources of different power densities, and the relative resistance of the conductive elastomer was recorded using a Keithley 2450 digital source instrument. The relationship between the resistance change and the irradiation time was also recorded.

[0088] The resistivity change rate of the TOH-3 sample in Example 1 under different light power densities is as follows: Figure 8 As shown, the range is 0.15~0.63 W / cm. 2 When illumination was applied within the specified optical power density range, the rate of change of resistance decreased significantly with increasing optical power density. However, when the illumination was turned off, the rate of change of resistance returned to 0, indicating that the TOH-3 sample exhibits a sensitive response to illumination within the aforementioned optical power density range. The illumination sensing test results of Examples 2-6 are similar to those of Example 1.

[0089] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a lignin-reinforced self-healing conductive elastomer, characterized in that, Includes the following steps: The lignin-reinforced self-healing conductive elastomer is obtained by mixing lipoic acid, lignin, metal acid salt ionic liquid and organic crosslinking agent and then heat-treating the mixture. The mass ratio of thioctic acid to lignin is 1:(0.025~0.055).

2. The preparation method according to claim 1, characterized in that, The mass ratio of thioctic acid to lignin is 1:(0.028~0.032).

3. The preparation method according to claim 1, characterized in that, Before mixing, the process includes a pretreatment step for lignin: mixing lignin with an organic solvent at 30-40°C for 1.8-3 hours, filtering the mixture, removing the organic solvent from the filtrate, and obtaining pretreated lignin.

4. The preparation method according to claim 1, characterized in that, The lignin is at least one of enzymatically hydrolyzed lignin, alkali lignin, or sulfonate lignin.

5. The preparation method according to claim 1, characterized in that, The metal element in the metal salt ionic liquid is at least one of Zn, Al, and Fe.

6. The preparation method according to claim 1, characterized in that, The organic crosslinking agent is at least one of polyethylene glycol diacrylate, 1,3-diisopropylbenzene, styrene, itaconic acid, 1,4-butylene diacrylate, hydroxyethyl methacrylate, and acrylic acid.

7. The preparation method according to claim 1, characterized in that, The heat treatment temperature is 55~65℃ and the time is 25~35min.

8. A lignin-reinforced self-healing conductive elastomer, characterized in that, It is prepared by any one of the preparation methods described in claims 1 to 7.

9. The application of the lignin-reinforced self-healing conductive elastomer of claim 8 in the preparation of flexible sensors.

10. A flexible sensor, characterized in that, It includes the lignin-reinforced self-healing conductive elastomer as described in claim 8.

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