Self-repairing acrylic acid-choline chloride-phytic acid-MXene conductive elastomer and preparation method thereof

Abstract

The invention discloses a self-repairing acrylic acid-choline chloride-phytic acid-MXene conductive elastomer and a preparation method thereof, and belongs to the application field of flexible wearable strain sensors. The invention aims to solve the problem that in the use process of the existing conductive elastomer, mechanical damage is caused by microcracks or external stress inevitably generated due to long-term service, so that the sensing performance is attenuated and even fails. The method comprises the following steps: adding choline chloride into acrylic acid, and stirring uniformly and transparently; adding phytic acid, and uniformly stirring; adding MXene, and uniformly stirring; and adding a cross-linking agent and an initiator, uniformly stirring, pouring into a polytetrafluoroethylene mold, and irradiating by using an ultraviolet light source. Through molecular structure design, a conductive network is introduced, and the self-repairing acrylic acid-choline chloride-phytic acid-MXene (ACPM) conductive elastomer with a highly dense hydrogen bond polymer network is prepared. The material can be used for intelligent materials such as flexible wearable equipment and sensors.

Description

Technical Field

[0001] The present invention belongs to the application field of flexible wearable strain sensors. Specifically, it relates to a self-healing acrylic-choline chloride-phytic acid-MXene (ACPM) conductive elastomer and a preparation method thereof. Background Art

[0002] The performance of conductive elastomers has an important impact on flexible wearable electronic devices. The excellent mechanical properties, electrical conductivity, and optical properties of conductive elastomers are highly compatible with the application scenarios of flexible wearable electronic devices. However, during the use of such materials, it is inevitable that microcracks will occur due to long-term service or mechanical damage caused by external stress, resulting in the attenuation or even failure of the sensing performance. Therefore, endowing conductive elastomers with self-healing properties, accelerating the self-healing speed, and improving the self-healing efficiency can effectively enhance the safety and stability of the materials and extend the service life of the materials, which is crucial for the development of the next generation of flexible wearable electronic devices.

[0003] In recent years, materials with self-healing properties have received extensive attention and made remarkable progress. Self-healing materials have not only achieved results in the repair of appearance and mechanical properties, but also demonstrated their great potential in extending service life, reducing maintenance costs, etc. in practical applications. However, most of the current research on self-healing materials still mainly focuses on restoring appearance and basic mechanical properties, and there is little systematic research on the progress of functional repair of materials.

[0004] For this type of self-healing material of conductive elastomers, especially in the application fields of flexible electronic devices, wearable devices, etc., the restoration of their repair functions is particularly important. Although the current self-healing methods can achieve a certain degree of repair, their self-healing time cycle is relatively long, and the performance recovery of many materials after self-healing still cannot match the original state. For example, how to maintain the stability of its electrical conductivity, elasticity, and mechanical properties during the self-healing process of conductive elastomer materials is still a technical problem to be solved urgently.

[0005] Therefore, the self-healing research of conductive elastomers should focus on improving their self-healing speed, efficiency, and durability. This is not only crucial for the research of conductive elastomers themselves, but also will have a profound impact on the innovative development of flexible wearable electronic devices, the technological progress of related industries, and the industrialization process. Therefore, in-depth exploration and realization of breakthroughs in highly efficient self-healing conductive elastomers will lay a solid foundation for the revolutionary progress of future flexible electronic technologies. Summary of the Invention

[0006] During the use of existing conductive elastomers, it is inevitable that microcracks will occur due to long-term service or mechanical damage will be caused by external stress, resulting in attenuation or even failure of the sensing performance. Therefore, endowing conductive elastomers with self-healing properties, accelerating the self-healing speed, and improving the self-healing efficiency can effectively enhance the safety and stability of the materials, extend the service life of the materials, and are crucial for the development of the next generation of flexible wearable electronic devices.

[0007] In the present invention, through molecular structure design and introduction of a conductive network, a self-healing acrylic acid-choline chloride-phytic acid-MXene (ACPM) conductive elastomer with a highly dense hydrogen bond polymer network is prepared. It is used in flexible wearable devices, and its self-healing property with high speed and high efficiency extends the service life of the devices.

[0008] The present invention provides a self-healing acrylic acid-choline chloride-phytic acid-MXene (ACPM) conductive elastomer and a preparation method thereof. The basic idea is that the introduction of multiple hydrogen bonds endows the ACPM conductive elastomer with excellent self-healing properties, the introduction of MXene provides good conductivity for the ACPM conductive elastomer, and the ACPM conductive elastomer has excellent sensing ability. The present invention further explores its application potential in the field of flexible wearable strain sensors.

[0009] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0010] The purpose of the present invention is to provide a preparation method of a self-healing acrylic acid-choline chloride-phytic acid-MXene conductive elastomer, which is characterized by including the following steps:

[0011] Step 1: Vacuum-dry choline chloride and then add it to acrylic acid, and stir evenly and transparently at a certain temperature;

[0012] Step 2: Then add phytic acid and stir evenly to obtain Solution A;

[0013] Step 3: Then add MXene and stir evenly;

[0014] Step 4: Then add a cross-linking agent and an initiator, stir evenly, pour it into a mold, and irradiate it with an ultraviolet light source to obtain the conductive elastomer.

[0015] Further limited, in Step 1, vacuum-dry for 2 h to 4 h under the conditions of a temperature of 30 °C to 80 °C and a vacuum degree of 5 MPa.

[0016] Further limited, in Step 1, the molar ratio of choline chloride to acrylic acid is 1∶(1.5 - 3).

[0017] Further limitation: In step one, stir under the conditions of a temperature of 60°C to 100°C and a stirring speed of 3000 rpm.

[0018] Further limitation: In step two, the mass ratio of phytic acid to acrylic acid is (0.1 - 0.3):1; the stirring speed is 3000 rpm.

[0019] Further limitation: In step three, the mass ratio of MXene to solution A is (0.001 - 0.05):1; the stirring speed is 3000 rpm.

[0020] Further limitation: In step four, the crosslinking agent is one or a combination of polyethylene glycol diacrylate, butanediol dimethacrylate, and hexanediol dimethacrylate in any ratio, and the molar ratio of the crosslinking agent to acrylic acid is (0.01 - 0.03):1.

[0021] Further limitation: In step four, the initiator is one or a combination of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone, 1-hydroxycyclohexyl phenyl ketone, and 2-hydroxy-2-methyl-1-phenyl-1-propanone in any ratio, and the molar ratio of the initiator to acrylic acid is (0.01 - 0.03):1.

[0022] Further limitation: In step four, stir under the condition of a stirring speed of 3000 rpm.

[0023] Further limitation: Under ultraviolet irradiation at an intensity of 10 mW / cm 2 ~30 mW / cm 2 for 5 min to 20 min.

[0024] The present invention also provides a composite acrylic acid-choline chloride-phytic acid-MXene (ACPM) conductive elastomer prepared by any of the above methods.

[0025] The conductive elastomer of the present invention uses acrylic acid as the matrix, adds choline chloride and phytic acid to the matrix to increase the number of hydrogen bonds; introduces MXene into the matrix to form a conductive network, thereby achieving a self-healing acrylic acid-choline chloride-phytic acid-MXene (ACPM) conductive elastomer.

[0026] In the above technical solution of the present invention, the purity of the chemical reagents used is not less than analytical pure.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The self-healing ACPM conductive elastomer prepared by the present invention, when used in flexible wearable devices, can automatically repair its structure and function after being damaged by external forces, can extend the service life of the device, and enhance the reliability of the device; moreover, the ACPM conductive elastomer can adapt to various deformations during human movement, improving comfort and durability.

[0029] The self-healing ACPM conductive elastomer prepared by the present invention exhibits excellent strain response ability by virtue of the excellent electrical conductivity of MXene. At the same time, the dense hydrogen bond network endows it with autonomous self-healing characteristics at room temperature. The electrical properties of this material can be repaired in only 0.6 seconds at room temperature, and the mechanical properties can bear a 200-gram weight within 1 minute after repair, with a repair efficiency of 63%. After 24 hours, its repair efficiency can recover to 93.2%.

[0030] The self-healing ACPM conductive elastomer prepared by the present invention has a simple preparation process, no pollution, low energy consumption, low cost, and high safety factor, and is suitable for industrial production. It provides an important reference and basis for further improving the self-healing efficiency of conductive elastomers. To further understand the features and technical content of the present invention, please refer to the following detailed description of the present invention and the attached drawings. However, the attached drawings are only for reference and illustration, and are not used to limit the present invention. Description of the Drawings

[0031] Figure 1 Infrared spectrum and nuclear magnetic resonance hydrogen spectrum of the prepared self-healing acrylic acid-choline chloride-phytic acid-MXene (ACPM) conductive elastomer: a) Infrared spectrum of the ACPM conductive elastomer; b) Nuclear magnetic resonance hydrogen spectrum of the ACPM conductive elastomer;

[0032] Figure 2 Optical transmittance curve of the prepared self-healing ACPM conductive elastomer;

[0033] Figure 3 Conductive properties of the self-healing ACPM conductive elastomers prepared in Examples 1, 2, 3, and 4: a) Impedance curve of the ACPM conductive elastomer; b) Conductivity of the ACPM conductive elastomer;

[0034] Figure 4 Self-healing process display of the prepared self-healing ACPM conductive elastomer: a) Self-healing process of the ACPM conductive elastomer; b) Lifting a 200-gram weight after 1 minute of repair of the ACPM conductive elastomer;

[0035] Figure 5SEM images of the self-healing ACPM conductive elastomer after self-healing for different times: a) SEM image of the ACPM conductive elastomer after healing for 0.5 hours; b) SEM image of the ACPM conductive elastomer after healing for 24 hours. Detailed implementation manners

[0036] The present invention will be described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, and at the same time do not limit the present invention in any form. It should be noted that for those of ordinary skill in the art, without departing from the inventive concept of the present invention, several modifications and improvements can be made. These all fall within the protection scope of the present invention.

[0037] Example 1: The preparation method of a self-healing acrylic acid-choline chloride-phytic acid-MXene (ACPM) conductive elastomer in this example is achieved through the following steps:

[0038] Step 1: Under a vacuum condition with a vacuum degree of 5 MPa, choline chloride is dried at 60 °C for 4 hours, and then 21 g is taken and added to 21 g of acrylic acid. It is stirred evenly and transparently at a temperature of 80 °C and 3000 rpm to obtain an acrylic acid-choline chloride mixed solution.

[0039] Step 2: 4.2 g of phytic acid is added to the acrylic acid-choline chloride mixed solution in Step 1 and stirred evenly at 3000 rpm to obtain an acrylic acid-choline chloride-phytic acid mixed solution.

[0040] Step 3: 0.231 g of MXene (Merck 12363-89-2) is added to the acrylic acid-choline chloride-phytic acid mixed solution in Step 2 and stirred evenly at 3000 rpm to obtain an acrylic acid-choline chloride-phytic acid-MXene solution.

[0041] Step 4: 0.402 g of polyethylene glycol diacrylate and 0.672 g of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone are added to the acrylic acid-choline chloride-phytic acid-MXene solution in Step 3 and stirred evenly at 3000 rpm to obtain a prepolymer solution. Subsequently, the prepolymer solution is poured into a polytetrafluoroethylene mold and irradiated with ultraviolet light at 10 mW / cm 2 for 5 minutes to obtain an ACPM type self-healing conductive elastomer.

[0042] Example 2: The preparation method of a self-healing acrylic acid-choline chloride-phytic acid-MXene (ACPM) conductive elastomer in this example is achieved through the following steps:

[0043] Step 1: Under a vacuum condition with a vacuum degree of 5 MPa, choline chloride was dried at 60 °C for 4 hours, then 7 g was taken and added to 10.5 g of acrylic acid. It was stirred evenly and transparently at a temperature of 60 °C and 3000 rpm to obtain an acrylic acid-choline chloride mixed solution;

[0044] Step 2: 1.2 g of phytic acid was added to the acrylic acid-choline chloride mixed solution in Step 1 and stirred evenly at 3000 rpm to obtain an acrylic acid-choline chloride-phytic acid mixed solution;

[0045] Step 3: 0.187 g of MXene (Merck 12363-89-2) was added to the acrylic acid-choline chloride-phytic acid mixed solution in Step 2 and stirred evenly at 3000 rpm to obtain an acrylic acid-choline chloride-phytic acid-MXene solution;

[0046] Step 4: 0.402 g of polyethylene glycol diacrylate and 0.672 g of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone were added to the acrylic acid-choline chloride-phytic acid-MXene solution in Step 3 and stirred evenly at 3000 rpm to obtain a prepolymer solution. Subsequently, the prepolymer solution was poured into a polytetrafluoroethylene mold and irradiated with ultraviolet light of 30 mW / cm 2 for 10 minutes to obtain an ACPM type self-healing conductive elastomer.

[0047] Example 3: The preparation method of a self-healing acrylic acid-choline chloride-phytic acid-MXene (ACPM) conductive elastomer in this example is realized through the following steps:

[0048] Step 1: Under a vacuum condition with a vacuum degree of 5 MPa, choline chloride was dried at 60 °C for 4 hours, then 14 g was taken and added to 21 g of acrylic acid. It was stirred evenly and transparently at a temperature of 100 °C and 3000 rpm to obtain an acrylic acid-choline chloride mixed solution;

[0049] Step 2: 2.1 g of phytic acid was added to the acrylic acid-choline chloride mixed solution in Step 1 and stirred evenly at 3000 rpm to obtain an acrylic acid-choline chloride-phytic acid mixed solution;

[0050] Step 3: 0.557 g of MXene (Merck 12363-89-2) was added to the acrylic acid-choline chloride-phytic acid mixed solution in Step 2 and stirred evenly at 3000 rpm to obtain an acrylic acid-choline chloride-phytic acid-MXene solution;

[0051] Step 4: Add 0.603 g of polyethylene glycol diacrylate and 1.008 g of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone to the acrylic acid-choline chloride-phytic acid-MXene solution in Step 3, stir evenly at 3000 rpm to obtain a prepolymer solution, and then pour the prepolymer solution into a polytetrafluoroethylene mold and irradiate it with ultraviolet light of 25 mW / cm 2 for 20 minutes to obtain an ACPM type self-healing conductive elastomer.

[0052] Example 4: The preparation method of a self-healing acrylic acid-choline chloride-phytic acid-MXene (ACPM) conductive elastomer in this example is achieved through the following steps:

[0053] Step 1: Under a vacuum condition with a vacuum degree of 5 MPa, dry choline chloride at 60 °C for 4 hours, then take 14 g and add it to 14 g of acrylic acid, and stir evenly and transparently at a temperature of 80 °C and 3000 rpm to obtain an acrylic acid-choline chloride mixed solution;

[0054] Step 2: Add 2.8 g of phytic acid to the acrylic acid-choline chloride mixed solution in Step 1, stir evenly at 3000 rpm to obtain an acrylic acid-choline chloride-phytic acid mixed solution;

[0055] Step 3: Add 0.536 g of MXene (Merck 12363-89-2) to the acrylic acid-choline chloride-phytic acid mixed solution in Step 2, stir evenly at 3000 rpm to obtain an acrylic acid-choline chloride-phytic acid-MXene solution;

[0056] Step 4: Add 0.402 g of polyethylene glycol diacrylate and 0.672 g of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone to the acrylic acid-choline chloride-phytic acid-MXene solution in Step 3, stir evenly at 3000 rpm to obtain a prepolymer solution, and then pour the prepolymer solution into a polytetrafluoroethylene mold and irradiate it with ultraviolet light of 20 mW / cm 2 for 15 minutes to obtain an ACPM type self-healing conductive elastomer.

[0057] The acrylic acid monomer, phytic acid monomer, and ACPM conductive elastomer were tested by Fourier transform infrared spectroscopy, and the test results are as Figure 1 shown in Figure 1 a. It can be seen from -1 a that the -C=C- double bond peak of acrylic acid at 1625 cm -1The -OH peak at [location] shifted in the ACPM conductive elastomer, indicating that a large number of hydrogen bonds were generated inside the ACPM conductive elastomer. The ACPM conductive elastomer was tested using a nuclear magnetic resonance hydrogen spectrum, and Figure 1 b; From Figure 1 b, it can be seen that the characteristic peaks at 6.01, 6.52, and 6.17 ppm together prove the existence of a polyacrylic acid network inside the ACPM conductive elastomer. The proton peaks at 3.19 ppm, 3.42 ppm, and 3.89 ppm come from choline chloride attached to the polyacrylic acid network. The proton peak at 4.47 ppm comes from phytic acid. These results together prove the existence of hydrogen bonds inside the ACPM conductive elastomer;

[0058] The transmittance of the ACPM conductive elastomer with a thickness of 1 mm prepared in Examples 1, 2, 3, and 4 was tested using an ultraviolet spectrophotometer, and the test results are as Figure 2 shown; From Figure 2 it can be seen that the addition of MXene will affect the transmittance of the ACPM conductive elastomer. And with the addition of MXene, although the transmittance of the ACPM conductive elastomer decreased slightly, the overall light transmittance effect is still excellent;

[0059] The ACPM conductive elastomers with different MXene addition amounts prepared in Examples 1, 2, 3, and 4 were tested for their AC impedance ( 5 ) between 1 - 10 Figure 3 Hz using an impedance meter, and their conductivity ( Figure 3 ) under the condition of 50 Hz was calculated in detail. From Figure 3 b, it can be seen that as the content of MXene increased from 0.5 wt% to 2 wt%, the conductivity of the ACPM conductive elastomer increased significantly from 0.007 S / m to 0.028 S / m, showing an improvement in the order of magnitude. This indicates that the addition of MXene has a positive effect on the conductivity of the conductive elastomer and effectively improves the electrical properties;

[0060] The damage - repair experiment of the ACPM conductive elastomer is shown in the repair process as Figure 4 shown. Figure 4 (a) shows the whole process of the damage - repair experiment of the ACPM conductive elastomer. First, a complete ACPM conductive elastomer was taken, and then it was cut into two parts from the middle position with a sharp knife. Finally, the two divided parts were re - aligned and contacted, and the whole damage - repair experiment was completed. Figure 4 (b) shows that the ACPM conductive elastomer that has just undergone the damage - repair experiment can immediately suspend a 200 g weight and deform under the induction of gravity;

[0061] SEM images of the self-healing ACPM conductive elastomer at different times are as follows Figure 5 shown. As can be seen from Figure 5 , when the ACPM conductive elastomer has just healed for 0.5 h, the fracture surface begins to connect, but there are still a small number of seams that are not in contact. When the healing time reaches 24 h, the incision is basically healed and the scar almost disappears. This is because the dynamic hydrogen bond network forces the polymer to diffuse between the fracture interfaces, thereby generating new crosslinks.

[0062] The specific embodiments of the present invention have been described above. It should be noted that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various deformations or modifications within the scope of the claims, which does not affect the essence of the present invention.

Claims

1. A method for preparing a self-healing acrylic acid-choline chloride-phytic acid-MXene conductive elastomer, characterized in that: The following steps are involved: Step 1, vacuum-dry choline chloride and add it to acrylic acid, and stir at a certain temperature until it becomes uniform and transparent; Step 2: then add phytic acid and stir evenly to obtain solution A; Step 3: Then add MXene and stir evenly; Step 4: Then add a crosslinking agent and an initiator, stir evenly, pour into a mold, and irradiate with an ultraviolet light source to obtain the conductive elastomer.

2. The method according to claim 1, characterized in that: Vacuum dry at 30℃~80℃ for 2h~4h.

3. The method according to claim 1, characterized in that: The molar ratio of choline chloride to acrylic acid is 1:(1.5-3).

4. The method according to claim 1, characterized in that: Stir at 60℃~100℃.

5. The method according to claim 1, characterized in that: The mass ratio of phytic acid to acrylic acid is (0.1-0.3):

1.

6. The method according to claim 1, characterized in that: The mass ratio of MXene to solution A is (0.001-0.05):

1.

7. The method according to claim 1, characterized in that: The crosslinking agent is one or a combination of polyethylene glycol diacrylate, butanediol dimethacrylate and hexanediol dimethacrylate, and the molar ratio of the crosslinking agent to acrylic acid is (0.01-0.03):

1.

8. The method according to claim 1, characterized in that: The initiator is one or a combination of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, and the molar ratio of the initiator to acrylic acid is (0.01-0.03):

1.

9. The method according to claim 1, characterized in that: Intensity: 10mW / cm 2 ~30mW / cm 2 Expose to ultraviolet light for 5 to 20 minutes.

10. A conductive elastomer prepared by the method according to any one of claims 1 to 9.

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