Preparation method of self-repairing bio-based glass-like polymer strain sensor material

Abstract

The invention provides a strain sensor material based on bio-based glass macromolecules and a preparation method thereof, and belongs to the technical field of polymer-based strain sensors. The strain sensor is an electronic device, can convert a strain signal into an electric signal, and is often applied to the field of flexible wearable equipment. However, traditional elastomer strain sensors are difficult to repair after being damaged, are mostly made of petroleum-based raw materials, and do not have environment-friendly performance. The bio-based recoverable strain sensor material is prepared by introducing amino-functionalized multi-walled carbon nanotubes into bio-based epoxy glass macromolecules based on sebacic acid, polyethylene glycol and glycyrrhizic acid. The material is composed of bio-based raw materials, is environment-friendly, and can realize stress relaxation through transesterification induced topological network rearrangement, so that the material has repairable and recoverable performance. In addition, as a strain sensor, the material can monitor human joint movement, and signals are stable and effective.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer-based strain sensors, and in particular relates to a method for preparing a self-repairing and recyclable bio-based glass-like polymer strain sensor material. Background Art

[0002] A strain sensor is a device used to detect the deformation of an object under the action of an external force. It can convert physical deformation into changes in electrical signals such as resistance, voltage, or frequency to achieve precise monitoring of deformation. In recent years, flexible strain sensors have attracted much attention due to their wide application in health monitoring, human-computer interaction, smart wearable devices, and other fields. Bio-based materials have been widely used in flexible strain sensors due to their environmental friendliness, renewability, and biocompatibility. Although traditional metal- or semiconductor-based strain sensors have excellent performance, they suffer from rigidity, brittleness, and poor biocompatibility, which limit their application in biomedical and wearable devices. In contrast, flexible strain sensors based on bio-based materials have gradually become a research hotspot due to their good biocompatibility, recyclability, and environmental friendliness.

[0003] In recent years, research on bio-based recyclable strain sensors has made significant progress, mainly focusing on dynamic cross-linking network design, gradient structure optimization, diversified applications of bio-based materials, and biodegradable and environmentally friendly properties.

[0004] Dynamic cross-linking networks are the core mechanism for achieving material recyclability. For example, Wu et al. reported that a supramolecular elastomer composite (SEC) was constructed by natural rubber (NR), polydopamine (PDA) and cellulose nanofibers (CNF), and the hydrogen bond network was used to achieve room temperature self-healing (80% strength recovery after 3 hours of repair). Based on the adhesion of PDA, carbon nanotubes (CNTs) were directly coated as a conductive layer, and the sensor sensitivity reached 2.71 (60-100% strain). Similarly, Xu et al. introduced photothermal responsive nanoparticles (such as Fe3O4@PDA) and triggered dynamic disulfide bond reconstruction through near-infrared light, achieving low-temperature (<80°C) recycling and reducing energy consumption by 40%. However, existing dynamic networks still face the challenges of high reconstruction temperature (such as some systems require above 120°C) and insufficient cycle stability (sensitivity attenuation >30% after multiple recycling).

[0005] The design of biological gradient structures significantly improves the sensitivity and mechanical adaptability of sensors. Xu et al. constructed a composite material with both strain and humidity sensing functions by gradient dispersion and orientation of a two-dimensional material (MXenes) in carboxyl styrene butadiene rubber (XSBR), and the stability of the conductive path was improved by 50% under small strain (<60%). The team further used gravity drive and hydrogen bonding to achieve a gradient distribution of MXenes, optimized the electron tunneling effect, and improved the sensor's ability to resist sweat interference in respiratory detection. In addition, Liu et al. used a double-layer cracked structure gelatin-based sensor, combined with a screen printing process, to achieve a gauge factor (GF value) of up to 1296, and successfully applied it to gesture recognition and robotic arm mapping.

[0006] Currently, bio-based materials such as polyvinyl alcohol (PVA), polylactic acid (PLA), chitosan (CS), and cellulose nanofibers (CFN) are widely used in the preparation of flexible sensors. For example, based on epoxy glass polymers (vitrimer), flexible polyethylene glycol (PEG) chains are introduced to form a covalent-noncovalent interpenetrating network, which makes the epoxy resin elastic and exhibits the advantages of processability, self-healing, and no small molecule release. Composite materials based on PVA and carbon nanotubes (CNT) have shown excellent mechanical and sensing properties. Bio-based sensors based on DNA-curcumin / graphene / polyethylene terephthalate (PET) have shown excellent strain regulation and electrochemical properties, suitable for real-time monitoring and feedback control. In addition, bio-based materials are gradually becoming a hot area of ​​research and application due to their unique advantages. Their types are becoming increasingly rich and their functions are continuously expanding, such as plant-based resins, polyurethane systems, and multifunctional composite materials.

[0007] Yang et al. improved the conductivity of pure bio-based films (such as chitosan and starch) to 1.2MPa tensile strength and GF value of 46.65 through surface graphitization strategy, and it is completely water-soluble, providing a new idea for solving the problem of electronic waste. Khalifa et al. combined flexible graphene with bio-based thermoplastic polyurethane (TPU) to prepare a piezoresistive sensor with a sensing coefficient of 11, and it still maintained high stability after more than 10,000 bending cycles. Zhang et al. used candle soot (CS), chitosan and Fe 3+ Using a coordination bond, a stretchable and biodegradable sensor has been developed. This sensor boasts a 200% elongation at break and a response time of just 0.22 seconds during swallowing testing, providing strong support for swallowing function testing in healthcare.

[0008] A strain sensor is an electronic device that can convert strain signals into electrical signals. Due to its excellent elasticity, stretchability, and biocompatibility, polymer matrices have become one of the most commonly used material matrices for strain sensors. Sensors constructed from polymer matrices provide a solid foundation for the application of flexible wearable devices. As one of the most commonly used polymer-based strain sensors, elastomers are favored by domestic and foreign scholars and the industrial community due to their advantages such as large deformation and high sensitivity. However, at present, traditional strain sensors rely on petroleum-based non-degradable materials, which have problems such as non-renewable resources, serious electronic waste pollution, and short device life. In addition, most elastomer strain sensors are difficult to repair after damage, cannot be recycled, and the raw materials are non-renewable. Therefore, self-healing strain sensor materials are one of the technical difficulties that need to be overcome in the field. Summary of the Invention

[0009] The purpose of the present invention is to prepare a strain sensor material based on bio-based glass-like polymers, and to utilize the topological network rearrangement reaction of glass-like polymers at high temperatures to achieve stress relaxation of the material, thereby enabling repair and recycling.

[0010] A method for preparing a strain sensor material based on a bio-based glass polymer, the method comprising the following steps:

[0011] ① Place amino-modified carbon nanotubes MWCNTs-NH2 in trifunctional epoxy resin TDE-85, stir and ultrasonicate to obtain a black glue solution;

[0012] ② Add the catalyst 1,5,7-triazabicyclo[4.4.0]dec-5-ene to the black latex, add sebacic acid in portions, stir and react to obtain a black latex;

[0013] ③ Add polyethylene glycol to the black latex and stir evenly, then add glycyrrhizic acid dropwise to the latex and continue stirring to obtain a black uniform emulsion;

[0014] ④Put the black uniform emulsion into the mold, preheat and then hot-press and solidify it to obtain a self-repairing bio-based glass polymer strain sensor material;

[0015] The amount of the amino carbon nanotubes MWCNTs-NH2 added is 3-5wt% of the trifunctional epoxy resin TDE-85;

[0016] The amount of sebacic acid added is calculated based on the carboxyl equivalent of sebacic acid, and the carboxyl group of sebacic acid accounts for 75-85% of the epoxy equivalent in the entire system;

[0017] The amount of polyethylene glycol added is 5-10% of the molar ratio of epoxy groups in the entire system;

[0018] The amount of glycyrrhizic acid added is 1-3% of the epoxy molar ratio in the entire system.

[0019] Wherein, the addition amount of the 1,5,7-triazabicyclo[4.4.0]dec-5-ene is 2-8% of the molar ratio of the carboxyl group in the entire reaction system.

[0020] Wherein, the relative molecular mass Mn of the polyethylene glycol is 2000.

[0021] The curing conditions of the hot pressing curing are curing at 120±10°C for 0.8 to 1.2 hours, curing at 150±10°C for 1.5 to 2.5 hours, and curing at 180±10°C for 1.5 to 2.5 hours.

[0022] Wherein, the pressure of the hot pressing curing is 5 to 20 MPa.

[0023] The ultrasonic treatment is specifically carried out at a power of 60 to 80 W for 10 to 20 minutes.

[0024] Wherein, in step ①, the stirring time is 10 to 30 minutes, in step ②, the stirring reaction time is 10 to 30 minutes, and in step ③, the stirring reaction time is 10 to 30 minutes.

[0025] Wherein, in the step ①, the temperature for stirring and ultrasonic treatment is 50-60°C.

[0026] Wherein, in step ② and step ③, the stirring reaction temperature is 70-80°C.

[0027] The construction of the above strain sensor materials includes raw materials and cross-linked network chemical structures such as the attached Figure 1 shown.

[0028] The above materials are used as the middle layer, and the materials are fixed with wires and medical tape to prepare strain sensors (such as Figure 1 As shown in the figure, the strain sensors attached to the knuckles, wrists and elbows can be tested for dynamic electrical signals through an electrochemical workstation to experiment with the effect of strain sensing.

[0029] Beneficial effects

[0030] This paper prepares a bio-based, recyclable strain sensor material by introducing amino-functionalized multi-walled carbon nanotubes into a bio-based epoxy glass polymer based on sebacic acid, polyethylene glycol, and glycyrrhizic acid. The material has a glass transition temperature below 0°C and maintains a highly elastic state at room temperature, allowing for cyclic stretching. The material also exhibits rapid stress relaxation at 150°C, making it repairable and recyclable. When applied to strain sensors, the material exhibits differentiated responses to human joint motion.

[0031] Since the polymer network of the present invention contains hydroxyl groups and ester bonds, an ester exchange reaction occurs at high temperature, causing the entire network to undergo topological rearrangement. According to the experimental results ( Figure 4 ), the strain sensor material prepared by the present invention has stress relaxation times τ* of 1862s, 1149s, and 1048s at 150°C for systems with 3wt%, 4wt%, and 5wt% carbon nanotube contents, respectively. The relaxation times measured by a rheometer show that as the MWCNTs-NH2 content increases from 3% to 5%, the system relaxation time gradually decreases from 1862s to 1048s, reflecting the significant regulatory effect of the filler on the relaxation behavior of the dynamic cross-linked network. This phenomenon is attributed to the synergistic effects of enhanced chemical cross-linking, physical entanglement, and dynamic bond activity initiated by amino groups on the MWCNTs-NH2 surface. Combined with the analysis of mechanical properties and swelling behavior, the shortening of the relaxation time is consistent with the improvement of material rigidity and the enhancement of network rearrangement ability.

[0032] Chemical degradation testing of the strain sensor material prepared according to the present invention revealed that, at 180°C, the relative mass of the 5% sample decreased significantly over time, reaching 73.94%, 33.49%, and 27.32% after 1, 2, and 3 hours, respectively, demonstrating a typical "rapid degradation followed by slow equilibrium" kinetic profile. The core driving force behind the degradation process is the alcoholysis of ester bonds. The ester bonds formed by the reaction of SA and TDE-85 in the material undergo nucleophilic substitution in the presence of high-temperature PEG, leading to the gradual disintegration of the cross-linked network. While the ether bonds of PEG do not directly participate in the degradation reaction, their hydrophilic segments facilitate penetration of the PEG solvent into the network, accelerating ester bond access and reaction efficiency.

[0033] According to the research on the sensing performance of the strain sensor material prepared by the present invention, taking the 5% system as an example, the stretching-recovery process of the sensor material in the knuckles, wrists and elbows is as follows: Figure 5 Experimental results show that the resistance change-time curves for strain sensing at different joints exhibit significantly different periodic characteristics. This behavior stems from the response characteristics of the material's conductive network to dynamic strain and the mechanical differences between different joint motion patterns. The sensor material exhibits differential responses to different human joint motions because its resistance change characteristics are closely related to the strain amplitude, motion frequency, and the reversible deformation capacity of the conductive network.

[0034] The present invention constructs a bio-based dynamic cross-linked network system: using sebacic acid (SA) as the matrix, combined with the topological reorganization characteristics of epoxy glass polymers to achieve material self-repair and degradable regeneration; constructing a three-dimensional conductive network through composite functionalized carbon nanotubes (MWCNTs-NH2), simultaneously improving conductivity and mechanical strength; introducing a rigid skeleton of glycyrrhizic acid to improve thermal stability, and its polyhydroxy structure cooperates with the PEG flexible chain segment to optimize the dynamic network reorganization efficiency, so that the material has both high ductility and damage self-repair ability.

[0035] The present invention solves the problem of non-renewable raw materials of traditional petroleum-based strain sensor materials. By designing an ester-exchanged glass-like polymer containing a polyhydroxy structure, the material is given rapid stress relaxation behavior at mild temperatures, thereby enabling the material to be repaired, recycled and reused. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 : Design diagram of bio-based strain sensor material.

[0037] Figure 2 : Schematic diagram of the assembly of strain sensor materials.

[0038] Figure 3 : The glass transition temperature of the material in Example 1.

[0039] Figure 4 : Stress relaxation behavior of the materials in Examples 1-3.

[0040] Figure 5 : Strain sensing behavior of the material in Example 1. DETAILED DESCRIPTION

[0041] The present invention is described in detail below with reference to examples. In the examples, the required reagents 4,5-epoxycyclohexane-1,2-dicarboxylic acid diglycidyl ester (TDE-85), 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), sebacic acid (SA), polyethylene glycol 2000 (PEG), the relative molecular mass of polyethylene glycol Mn=2000, and glycyrrhizic acid (GL) are manufactured by Anaiji Chemical; amino-modified carbon nanotubes (MWCNTs-NH2) are purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.

[0042] Differential Scanning Calorimetry

[0043] Use a differential scanning calorimeter to test the sensor material. Take a small amount of the sample to be tested (about 3 mg), spread the block sample on the bottom of the crucible, and select an inert material with a heat capacity close to that of the sample (such as an empty crucible) as a reference. Set the temperature range to -80°C to 200°C, and the heating rate to 20°C / min. Place the sample crucible and the reference crucible in the DSC furnace respectively to ensure good contact. Close the furnace lid and wait for the temperature to stabilize. Start the program, and the instrument automatically records the heat flow difference (ΔQ) between the sample and the reference as the temperature / time changes, and observes the heat flow curve in real time to ensure there are no abnormal fluctuations.

[0044] Determination of glue content

[0045] The dried sample (about 50 mg, m0) was immersed in 10 mL of solvent (ethyl acetate, acetone and dichloromethane, respectively) at room temperature. After 20 h, the sample was taken out and transferred to a 60 °C oven for drying. After 10 h, it was weighed (m1).

[0046] The calculation formula for glue content is: Determination of swelling rate in water

[0047] At room temperature, take about 40 mg of dry sample (m0) and put it into 10 ml of deionized water. Take out the sample at different times, then absorb the water with filter paper and weigh it (m1).

[0048] The swelling rate calculation formula is: Method for determining tensile properties

[0049] Test using a universal testing machine. Cut dumbbell-shaped specimens according to ASTM standards, measure the specimen's original dimensions (gauge length, width, thickness), and calculate the initial cross-sectional area. Select an appropriate fixture and clamp the specimen vertically between the upper and lower fixtures, ensuring that the specimen axis aligns with the direction of tension to avoid eccentric loading. Apply a small preload to eliminate gaps in the fixtures and prevent initial slippage. Start the testing machine, initiate automatic loading, and observe the stress-strain curve in real time.

[0050] Stress relaxation determination method

[0051] Test using a rheometer. Select the sample size based on the rheometer fixture to ensure uniformity and bubble-free sample. Load the disc-shaped sample onto the center of the lower plate. Slowly lower the upper plate to the desired gap, applying a small normal vector and returning to zero to ensure uniform contact. Heat the sample to 150°C and perform a dynamic strain sweep to monitor the material's stress and modulus over time and observe relaxation behavior.

[0052] Determination of chemical degradation

[0053] Place a rectangular sample with a mass of 20-30 mg (m0) in a 10 mL sample vial. Add 5 mL of ethylene glycol (EG) to the sample vial and perform chemical degradation at 180°C. Remove the sample after 1, 2, and 3 hours and dry it in an oven at 180°C. After drying, rinse the sample several times in anhydrous ethanol and continue drying in an oven at 180°C until the sample weighs a constant weight. The mass (m1) is then measured.

[0054] The calculation formula for the relative mass of the degradation process is: Method for measuring sensing performance

[0055] Dynamic electrical signal testing of flexible sensors attached to the knuckles, wrist, and elbow was performed using an electrochemical workstation. First, copper sheets were placed at both ends of the sensor's rectangular spline. The sensor spline was then adhered to the test joint using medical tape. The electrochemical workstation and computer were powered on and the instrument self-test was completed. The working electrode, reference electrode, and counter electrode were connected to the corresponding ports on the electrochemical workstation. The electrochemical workstation's control software was then launched on the computer. A resistance change-time curve was generated for the elbow joint. Multiple tests were performed on the same body part to observe the material's sensing performance.

[0056] Example 1

[0057] This embodiment provides a method for preparing a self-repairing, recyclable bio-based glass polymer strain sensor material, which specifically includes the following steps:

[0058] First, add 1.0g of MWCNTs-NH2 (5wt%) to 20.0g of TDE-85 and stir at 50°C for 20 minutes to thoroughly mix. The mixture is then ultrasonicated at 80W for 15 minutes to produce a black latex. Next, heat the black latex to 70°C and add 1.12g of TBD. Stir for 15 minutes to ensure that the TBD is evenly dispersed throughout the latex. Add 16.2g of SA to the latex in small portions over several times. Once all the SA has been added, continue stirring for 20 minutes to produce a black latex. Then, add 20.12g of PEG to the black latex and stir until evenly mixed. Then, slowly add 1.66g of GL. After the addition is complete, continue stirring at 70°C for 20 minutes to form a uniform black latex. Pour the uniform black latex into a mold, place it on a flat-plate vulcanizer, and preheat at 120°C for 30 minutes. After preheating, hot pressing and curing were carried out in the following process sequence: hot pressing pressure of 10 MPa, curing at 120°C for 1 hour, curing at 150°C for 2 hours, and curing at 180°C for 2 hours, and finally the strain sensor material was obtained.

[0059] The glass transition temperature of the material is -31.50℃( Figure 3 The relaxation time at 150°C is 1048s ( Figure 4 As shown in the figure, it shows that the material is repairable and recyclable at 150℃. Figure 2 The method shown here assembles strain sensor materials to detect human motion. Experimental results show that the resistance change-time curves for strain sensing performance at different joints exhibit significantly different periodic characteristics. This behavior stems from the response characteristics of the material's conductive network to dynamic strain and the mechanical differences in different joint motion patterns ( Figure 5 In summary, the material can achieve good strain sensing stability.

[0060] Table 1 Degradation data of Example 1 in EG

[0061]

[0062] Example 2

[0063] This embodiment provides a method for preparing a self-repairing, recyclable bio-based glass polymer strain sensor material, which specifically includes the following steps.

[0064] First, add 0.8g MWCNTs-NH2 (4wt%) to 20.0g TDE-85 and stir at 50°C for 20 minutes to thoroughly mix. The mixture is then ultrasonicated at 80W for 15 minutes to produce a black latex. Next, heat the black latex to 70°C and add 1.12g TBD. Stir for 15 minutes to ensure that the TBD is evenly dispersed throughout the latex. Add 16.2g SA to the latex in small portions over several times. Once all the SA has been added, continue stirring for 20 minutes to produce a black latex. Then, add 20.12g PEG to the black latex and stir until evenly mixed. Then, slowly add 1.66g GL. After the addition is complete, continue stirring at 70°C for 20 minutes to form a uniform black latex. Pour the uniform black latex into a mold, place it on a flat-plate vulcanizer, and preheat at 120°C for 30 minutes. After preheating, hot pressing and curing were carried out in the following order: hot pressing pressure 5 MPa, curing at 120°C for 1 hour, curing at 150°C for 2 hours, and curing at 180°C for 2 hours, and finally the strain sensor material was obtained. The relaxation time of the material at 150°C was 1149s ( Figure 4 This indicates that the material is repairable and recyclable at 150°C.

[0065] Example 3

[0066] This embodiment provides a method for preparing a self-repairing, recyclable bio-based glass polymer strain sensor material, which specifically includes the following steps.

[0067] First, add 0.6g MWCNTs-NH2 (3wt%) to 20.0g TDE-85 and stir at 50°C for 20 minutes to thoroughly mix. The mixture is then ultrasonicated at 80W for 15 minutes to produce a black latex. Next, heat the black latex to 70°C and add 1.12g TBD. Stir for 15 minutes to ensure that the TBD is evenly dispersed throughout the latex. Add 17.2g SA to the latex in small portions over several times. Once all the SA has been added, continue stirring for 20 minutes to produce a black latex. Then, add 20.12g PEG to the black latex and stir until evenly mixed. Then, slowly add 1.66g GL. After the addition is complete, continue stirring at 70°C for 20 minutes to form a uniform black latex. Pour the uniform black latex into a mold, place it on a flat-plate vulcanizer, and preheat at 120°C for 30 minutes. After preheating, hot pressing and curing were carried out in the following order: hot pressing pressure 20 MPa, curing at 120°C for 1 hour, curing at 150°C for 2 hours, and curing at 180°C for 2 hours, and finally the strain sensor material was obtained. The relaxation time of the material at 150°C was 1864s ( Figure 4 This indicates that the material is repairable and recyclable at 150°C.

[0068] Example 4

[0069] This embodiment provides a method for preparing a self-repairing, recyclable bio-based glass polymer strain sensor material, which specifically includes the following steps:

[0070] First, add 1.0g of MWCNTs-NH2 (5wt%) to 20.0g of TDE-85 and stir at 52°C for 10 minutes to thoroughly mix. The mixture is then ultrasonicated at 60W for 10 minutes to produce a black latex. Next, heat the black latex to 72°C, add 0.45g of TBD, and continue stirring for 10 minutes to ensure that the TBD is evenly dispersed throughout the latex. Add 15.2g of SA to the latex in small portions over several times. Once all the SA has been added, continue stirring for 10 minutes to produce a black latex. Add 10.06g of PEG to the black latex, stir thoroughly, and then slowly add 0.55g of GL. After the addition is complete, continue stirring at 72°C for 10 minutes to form a uniform black latex. Pour the uniform black latex into a mold, place it on a flat-plate vulcanizer, and preheat it at 110°C for 50 minutes. After preheating, hot pressing and curing were carried out in the following process sequence: hot pressing pressure 20 MPa, curing at 110°C for 1.2 h, curing at 140°C for 2.5 h, and curing at 170°C for 2.5 h, and finally the strain sensor material was obtained.

[0071] Example 5

[0072] This embodiment provides a method for preparing a self-repairing, recyclable bio-based glass polymer strain sensor material, which specifically includes the following steps:

[0073] First, add 0.6g MWCNTs-NH2 (3wt%) to 20.0g TDE-85 and stir at 60°C for 30 minutes to thoroughly mix. The mixture is then ultrasonicated at 70W for 20 minutes to produce a black latex. Next, heat the black latex to 80°C and add 1.79g TBD. Stir for 10 minutes to ensure that the TBD is evenly dispersed throughout the latex. Add 16.2g SA to the latex in small portions over several times. Once all the SA has been added, continue stirring for 30 minutes to produce a black latex. Add 15.00g PEG to the black latex and stir until evenly mixed. Then, slowly add 1.0g GL. After the addition is complete, continue stirring at 80°C for 30 minutes to form a uniform black latex. Pour the uniform black latex into a mold, place it on a flat-plate vulcanizer, and preheat it at 130°C for 10 minutes. After preheating, hot pressing and curing were carried out in the following process sequence: hot pressing pressure of 10 MPa, curing at 130°C for 0.8 h, curing at 160°C for 1.5 h, and curing at 170°C for 1.5 h, to finally obtain the strain sensor material.

Claims

1. A method for preparing a self-repairing bio-based glass polymer strain sensor material, characterized in that: The steps include: ① Place amino-modified carbon nanotubes MWCNTs-NH2 in trifunctional epoxy resin TDE-85, stir and ultrasonicate to obtain a black glue solution; ② Add the catalyst 1,5,7-triazabicyclo[4.4.0]dec-5-ene to the black latex, add sebacic acid in portions, stir and react to obtain a black latex; ③ Add polyethylene glycol to the black latex and stir evenly, then add glycyrrhizic acid dropwise to the latex and continue stirring to obtain a black uniform emulsion; ④Put the black uniform emulsion into the mold, preheat and then hot-press and solidify it to obtain a self-repairing bio-based glass polymer strain sensor material; The amount of the amino carbon nanotubes MWCNTs-NH2 added is 3-5 wt% of the trifunctional epoxy resin TDE-85; The amount of sebacic acid added is calculated based on the carboxyl equivalent of sebacic acid, and the carboxyl group of sebacic acid accounts for 75-85% of the epoxy equivalent in the entire system; The amount of polyethylene glycol added is 5-10% of the epoxy molar ratio in the entire system; The added amount of the glycyrrhizic acid is 1-3% of the molar ratio of the epoxy groups in the whole system.

2. The method for preparing the self-repairing bio-based glass polymer strain sensor material according to claim 1, characterized in that: The added amount of the 1,5,7-triazabicyclo[4.4.0]dec-5-ene is 2-8% of the molar ratio of the carboxyl group in the entire reaction system.

3. The method for preparing the self-repairing bio-based glass polymer strain sensor material according to claim 1, characterized in that: The relative molecular mass Mn of the polyethylene glycol is 2000.

4. The method for preparing the self-repairing bio-based glass polymer strain sensor material according to claim 1, characterized in that: The curing conditions of the hot pressing curing are curing at 120±10°C for 0.8~1.2h, curing at 150±10°C for 1.5~2.5h, and curing at 180±10°C for 1.5~2.5h.

5. The method for preparing the self-repairing bio-based glass polymer strain sensor material according to claim 1, characterized in that: The pressure of the hot pressing curing is 5-20 MPa.

6. The method for preparing the self-repairing bio-based glass polymer strain sensor material according to claim 1, characterized in that: The ultrasonic treatment is specifically carried out at a power of 60-80W for 10-20min.

7. The method for preparing the self-repairing bio-based glass polymer strain sensor material according to claim 1, characterized in that: In step ①, the stirring time is 10 to 30 minutes, in step ②, the stirring reaction time is 10 to 30 minutes, and in step ③, the stirring reaction time is 10 to 30 minutes.

8. The method for preparing the self-repairing bio-based glass polymer strain sensor material according to claim 1, characterized in that: In the step ①, the temperature for stirring and ultrasonic treatment is 50-60°C.

9. The method for preparing the self-repairing bio-based glass polymer strain sensor material according to claim 1, characterized in that: In step ② and step ③, the stirring reaction temperature is 70-80°C.

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