Conductive polymer hydrogel with high tensile property and self-healing property as well as preparation method and application of conductive polymer hydrogel

Abstract

The invention discloses conductive polymer hydrogel with high tensile property and self-healing property as well as a preparation method and application thereof, and belongs to the technical field of conductive hydrogel. The conductive polymer hydrogel is prepared from the following raw materials: 1 to 6 mol / L of lithium salt, and the following components in percentage by mass: 10 to 12 percent of acrylamide, 0.5 to 0.6 percent of xanthan gum, 0.2 to 0.6 percent of initiator, 0.001 to 0.01 percent of N, N '-methylene bisacrylamide and the balance of water. The conductive polymer hydrogel disclosed by the invention has high conductivity, excellent mechanical property and good biocompatibility.

Description

Technical Field

[0001] The present invention relates to the technical field of conductive hydrogels, and particularly to a conductive polymer hydrogel with high stretchability and self-healing properties, and its preparation method and application. Background Art

[0002] Conductive hydrogels, as a composite material combining the characteristics of hydrogels and conductive materials, have received extensive attention in recent years in fields such as sensors, electronic skins, and energy storage devices. Conductive hydrogels are mainly divided into two categories: A. Natural polymer-based conductive hydrogels: These hydrogels are usually composed of natural polysaccharides (such as gelatin, xanthan gum, carboxymethyl cellulose, etc.) and conductive salts (such as lithium chloride, sodium chloride, etc.). Such materials have the advantages of natural origin, environmental friendliness, and biocompatibility, but their conductive properties may be relatively limited, and it is necessary to finely adjust the formula to improve the conductive properties. B. Synthetic polymer-based conductive hydrogels: These hydrogels often use polymers such as polyacrylamide (PAM), polyvinyl alcohol (PVA), etc., combined with conductive fillers (such as carbon nanotubes, graphene, etc.) to improve their conductive properties. Such hydrogels usually have good mechanical properties, but their biocompatibility and biodegradability need to be further optimized. The preparation methods of conductive hydrogels mainly include the following: A. Physical cross-linking method of hydrogels: The hydrogel is formed into a cross-linked network structure by physical methods (such as freeze-thaw method, hydrogen bond cross-linking, etc.). This method is simple and non-toxic, but the controllability of its structure and conductive properties is poor. B. Chemical cross-linking method: The hydrogel is cross-linked into a three-dimensional network structure by chemical cross-linking agents (such as glutaraldehyde, ammonium persulfate, etc.). This method can effectively improve the mechanical strength and stability of the hydrogel, but may introduce toxic components and affect biocompatibility. C. Solution impregnation method: This method increases the conductivity of the hydrogel by impregnating the hydrogel with a conductive salt solution. This method is easy to operate, but during the impregnation process with a high-concentration salt solution, the swelling property and mechanical strength of the hydrogel may be affected.

[0003] Although conductive hydrogels have shown good application prospects in many fields, they still face several challenges in practical applications. For example: A. Insufficient conductivity: The conductive properties of many hydrogels are limited by their structural design, especially natural polymer-based conductive hydrogels. The ion conduction paths are not sufficiently connected, resulting in low conductive efficiency. B. Poor mechanical properties: Although many conductive hydrogels have certain flexibility and stretchability, they are prone to fracture or failure under high strain, limiting their applications in fields such as wearable devices and artificial electronic skin. C. Biocompatibility and stability issues: Some synthetic polymer conductive hydrogels have good conductivity and mechanical properties, but they may lack biocompatibility or are easily degraded in a humid environment, resulting in unstable long-term performance. D. Complex preparation methods and high costs: Some existing conductive hydrogel preparation methods are complex, costly, and may involve toxic or difficult-to-degrade chemical cross-linking agents, which are not conducive to large-scale production and environmental friendliness. Summary of the Invention

[0004] The object of the present invention is to provide a conductive polymer hydrogel with high stretchability and self-healing properties, as well as its preparation method and application, to solve the problems existing in the above-mentioned prior art.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] One of the technical solutions of the present invention: A conductive polymer hydrogel with high stretchability and self-healing properties, the raw materials include a lithium salt with a concentration of 1-6 mol / L, and the following components by mass percentage: acrylamide 10-12%, xanthan gum 0.5-0.6%, initiator 0.2-0.6%, N,N'-methylenebisacrylamide 0.001-0.01%, and the balance is water.

[0007] The lithium salt with a concentration of 1-6 moL / L represents that the concentration of the lithium salt in the mixed system composed of acrylamide, xanthan gum, initiator, N,N'-methylenebisacrylamide, lithium salt and water is 1-6 mol / L.

[0008] The conductive polymer hydrogel with high stretchability and self-healing properties of the present invention is actually a polyacrylamide / xanthan gum / lithium salt conductive double network hydrogel (abbreviated as PAM / XG / Li + DN), which solves the above problems existing in the prior art. Compared with the prior art, it has the following effects:

[0009] (1) Improve conductivity: By introducing a lithium salt as a conductive salt, it can not only provide rich ion conduction paths, but also connect these ion channels through the water molecules in the hydrogel, thereby greatly improving the conductive performance of the hydrogel.

[0010] (2) Improve mechanical properties: By constructing a double-network structure, the two cross-linked networks formed by PAM and XG can effectively enhance the mechanical strength of the hydrogel, improve its stretchability and flexibility, and overcome the problem that traditional conductive hydrogels are prone to breakage under high strain.

[0011] (3) Enhance biocompatibility and environmental friendliness: As a natural polysaccharide, xanthan gum itself has good biocompatibility. When it is compounded with acrylamide to prepare a hydrogel, it can effectively improve the biocompatibility of the polyacrylamide hydrogel system; in addition, xanthan gum not only has good biocompatibility but also helps to enhance the environmental protection of the hydrogel, avoiding the biodegradation problems of some synthetic polymer materials.

[0012] (4) Simplify the preparation process and reduce costs: The hydrogel preparation method proposed in the present invention is relatively simple and has low costs. At the same time, its properties can be adjusted by controlling the monomer concentration, reaction temperature, initiator dosage, lithium salt concentration, and the design of the hydrogel network structure.

[0013] Further, the initiator is ammonium persulfate.

[0014] Further, the lithium salt is lithium chloride.

[0015] The second technical solution of the present invention: The preparation method of the above-mentioned conductive polymer hydrogel with high stretchability and self-healing properties includes the following steps:

[0016] Mix acrylamide, xanthan gum, initiator, N,N'-methylenebisacrylamide, lithium salt, and water, and carry out a reaction under heat preservation conditions to obtain the conductive polymer hydrogel with high stretchability and self-healing properties.

[0017] Under heat preservation conditions, the initiator releases free radicals when heated, initiating the polymerization of monomers to obtain a conductive polymer hydrogel.

[0018] Further, the temperature of the heat preservation is 55 - 75 °C; the reaction time is 1 - 5 h.

[0019] Further, the mixing of acrylamide, xanthan gum, initiator, N,N'-methylenebisacrylamide, lithium salt, and water includes: mixing acrylamide, xanthan gum, N,N'-methylenebisacrylamide, lithium salt, and water, stirring evenly, then introducing nitrogen for oxygen removal, and then adding the initiator and removing bubbles.

[0020] Further, the time for oxygen removal is 30 min.

[0021] Further, the removal of bubbles is achieved by low-speed centrifugation.

[0022] The third technical solution of the present invention: Application of the above-mentioned conductive polymer hydrogel with high tensile and self-healing properties in the preparation of intelligent sensors, electronic skin or energy storage devices.

[0023] The present invention discloses the following technical effects:

[0024] The conductive polymer hydrogel with high tensile and self-healing properties of the present invention, namely polyacrylamide / xanthan gum / lithium salt conductive double network hydrogel (PAM / XG / Li + DN), not only endows the hydrogel with high conductivity, but also improves the interaction between the cross-linked networks of the hydrogel, has excellent mechanical properties, and has biocompatibility, which can meet the application requirements of high-demand fields such as medical treatment, intelligent sensors, electronic skin, and energy storage devices. Description of the Drawings

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0026] Figure 1 Infrared spectrum of the PAM / XG / Li + DN hydrogel prepared in Example 19;

[0027] Figure 2 In the case of the PAM / XG / Li prepared in Example 19 + Thermogravimetric spectrum of the DN hydrogel;

[0028] Figure 3 In the case of the PAM / XG / Li prepared in Example 19 + SEM images of the PAM / XG / Li DN hydrogel after water absorption swelling and freeze-drying, where (a)-(d) are SEM images at different magnification ratios;

[0029] Figure 4 Cyclic tensile test results (cyclic hysteresis curve) of the PAM / XG / Li+DN hydrogel prepared in Example 19;

[0030] Figure 5 In the case of the PAM / XG / Li prepared in Example 19 + Conductivity test process and results of the PAM / XG / Li DN hydrogel. Among them, A is a photo of the circuit composed of a small light bulb and conductive tape, B is a photo after applying voltage with the PAM / XG / Li + DN hydrogel as a conductor connecting the conductive tape, and C is the PAM / XG / Li +Photo of the cut DN hydrogel, where D is PAM / XG / Li + Photo of the DN hydrogel after being reassembled together again. Detailed implementation mode

[0031] Now, various exemplary embodiments of the present invention will be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, characteristics, and implementation schemes of the present invention.

[0032] It should be understood that the terms described in the present invention are only for describing specific implementation modes and are not used to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0033] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the said documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0034] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific implementation modes of the present invention specification, which are obvious to those skilled in the art. Other implementation modes obtained from the present invention specification are obvious to those skilled in the art. The present invention specification and examples are only exemplary.

[0035] Regarding the use of "comprising", "including", "having", "containing", etc. in this article, they are all open-ended terms, meaning including but not limited to.

[0036] It should be noted that those aspects not described in detail in the present invention are all conventional operation means in the art and are not the focus of the present invention.

[0037] In the specific implementation mode of the present invention, if it involves room temperature or normal temperature, it specifically refers to 20 - 30 °C.

[0038] The "parts" involved in the following examples and comparative examples of the present invention are all "parts by mass".

[0039] All raw materials used in the following examples and comparative examples of the present invention are ordinary commercially available products.

[0040] Example 1

[0041] The preparation of the polymer hydrogel matrix is as follows:

[0042] (1) By mass percentage, weigh 11.6615% of acrylamide, 0.5831% of xanthan gum, 0.2915% of ammonium persulfate, 0.0029% of N,N'-methylenebisacrylamide, and the balance is distilled water;

[0043] (2) Mix acrylamide, xanthan gum, N,N'-methylenebisacrylamide and distilled water in a beaker, first stir evenly with a glass rod, then stir with a magnetic stirrer for 30 min, and pass nitrogen to remove oxygen for 30 min. Then add the initiator ammonium persulfate, and centrifuge at low speed in a low-speed centrifuge to remove air bubbles. Then place the mixed solution in a water bath and heat it to 60 °C and keep it warm for reaction for 3 h. After the reaction is completed, take out the sample to obtain the polymer hydrogel matrix.

[0044] Example 2

[0045] The preparation of the polymer hydrogel matrix is as follows:

[0046] (1) By mass percentage, weigh 11.6683% of acrylamide, 0.5834% of xanthan gum, 0.2334% of ammonium persulfate, 0.0029% of N,N'-methylenebisacrylamide, and the balance is distilled water;

[0047] Step (2) is the same as that in Example 1.

[0048] Example 3

[0049] The preparation of the polymer hydrogel matrix is as follows:

[0050] (1) By mass percentage, weigh 11.6445% of acrylamide, 0.5822% of xanthan gum, 0.4367% of ammonium persulfate, 0.0029% of N,N'-methylenebisacrylamide, and the balance is distilled water;

[0051] Step (2) is the same as that in Example 1.

[0052] Example 4

[0053] The preparation of the polymer hydrogel matrix is as follows:

[0054] (1) By mass percentage, weigh 11.6343% of acrylamide, 0.5817% of xanthan gum, 0.5235% of ammonium persulfate, 0.0029% of N,N'-methylenebisacrylamide, and the balance is distilled water;

[0055] Step (2) is the same as that in Example 1.

[0056] Example 5

[0057] Preparation of the polymer hydrogel matrix is carried out as follows:

[0058] (1) Weigh acrylamide 10.1649%, xanthan gum 0.5083%, ammonium persulfate 0.3812%, N,N'-methylenebisacrylamide 0.0025% and the balance being distilled water by mass percentage;

[0059] Step (2) is the same as that in Example 1.

[0060] Example 6

[0061] It is the same as Example 3, with the only difference being that the temperature of the heat preservation reaction is 55°C.

[0062] Example 7

[0063] It is the same as Example 3, with the only difference being that the temperature of the heat preservation reaction is 65°C.

[0064] Example 8

[0065] It is the same as Example 3, with the only difference being that the temperature of the heat preservation reaction is 70°C.

[0066] Example 9

[0067] It is the same as Example 3, with the only difference being that the temperature of the heat preservation reaction is 75°C.

[0068] Example 10

[0069] It is the same as Example 7, with the only difference being that the time of the heat preservation reaction is 1 h.

[0070] Example 11

[0071] It is the same as Example 7, with the only difference being that the time of the heat preservation reaction is 1.5 h.

[0072] Example 12

[0073] It is the same as Example 7, with the only difference being that the time of the heat preservation reaction is 2 h.

[0074] Example 13

[0075] It is the same as Example 7, with the only difference being that the time of the heat preservation reaction is 4 h.

[0076] Example 14

[0077] Preparation of the polymer hydrogel matrix is carried out as follows:

[0078] (1) Weigh acrylamide at 11.6447% by mass percentage, xanthan gum at 0.5822%, ammonium persulfate at 0.4367%, N,N'-methylenebisacrylamide at 0.0015%, and the balance is distilled water;

[0079] (2) Mix acrylamide, xanthan gum, N,N'-methylenebisacrylamide and distilled water in a beaker. First, stir evenly with a glass rod, then stir with a magnetic stirrer for 30 min, and pass nitrogen to remove oxygen for 30 min. Then add the initiator ammonium persulfate, and centrifuge at low speed in a low-speed centrifuge to remove air bubbles. Then place the mixed solution in a water bath and heat it to 65 °C and keep it reacting for 2 h. After the reaction is completed, take out the sample to obtain the polymer hydrogel matrix.

[0080] Example 15

[0081] The preparation of the polymer hydrogel matrix is as follows:

[0082] (1) Weigh acrylamide at 11.6443% by mass percentage, xanthan gum at 0.5822%, ammonium persulfate at 0.4367%, N,N'-methylenebisacrylamide at 0.0044%, and the balance is distilled water;

[0083] Step (2) is the same as that in Example 14.

[0084] Example 16

[0085] The preparation of the polymer hydrogel matrix is as follows:

[0086] (1) Weigh acrylamide at 11.6442% by mass percentage, xanthan gum at 0.5822%, ammonium persulfate at 0.4367%, N,N'-methylenebisacrylamide at 0.0058%, and the balance is distilled water;

[0087] Step (2) is the same as that in Example 14.

[0088] Example 17

[0089] The preparation of the polymer hydrogel matrix is as follows:

[0090] (1) Weigh acrylamide at 11.6438% by mass percentage, xanthan gum at 0.5822%, ammonium persulfate at 0.4366%, N,N'-methylenebisacrylamide at 0.0087%, and the balance is distilled water;

[0091] Step (2) is the same as that in Example 14.

[0092] Comparative Example 1

[0093] The preparation of the polymer hydrogel matrix is as follows:

[0094] (1) Weigh acrylamide 6.2110%, xanthan gum 0.3105%, ammonium persulfate 0.3105%, N,N'-methylenebisacrylamide 0.0031% and the balance of distilled water by mass percentage;

[0095] Step (2) is the same as that in Example 1.

[0096] Comparative Example 2

[0097] The preparation of the polymer hydrogel matrix is as follows:

[0098] (1) Weigh acrylamide 9.0359%, xanthan gum 0.3012%, ammonium persulfate 0.3012%, N,N'-methylenebisacrylamide 0.0030% and the balance of distilled water by mass percentage;

[0099] Step (2) is the same as that in Example 1.

[0100] Comparative Example 3

[0101] The preparation of the polymer hydrogel matrix is as follows:

[0102] (1) Weigh acrylamide 11.6956%, xanthan gum 0.2924%, ammonium persulfate 0.2924%, N,N'-methylenebisacrylamide 0.0029% and the balance of distilled water by mass percentage;

[0103] Step (2) is the same as that in Example 1.

[0104] Comparative Example 4

[0105] The preparation of the polymer hydrogel matrix is as follows:

[0106] (1) Weigh acrylamide 14.2041%, xanthan gum 0.2841%, ammonium persulfate 0.2841%, N,N'-methylenebisacrylamide 0.0028% and the balance of distilled water by mass percentage;

[0107] Step (2) is the same as that in Example 1.

[0108] Comparative Example 5

[0109] The preparation of the polymer hydrogel matrix is as follows:

[0110] (1) Weigh acrylamide 16.5741%, xanthan gum 0.2762%, ammonium persulfate 0.2762%, N,N'-methylenebisacrylamide 0.0028% and the balance of distilled water by mass percentage;

[0111] Step (2) is the same as that in Example 1.

[0112] Comparative Example 6

[0113] Preparation of the polymer hydrogel matrix is carried out as follows:

[0114] (1) Weigh acrylamide 11.7127%, xanthan gum 0.1464%, ammonium persulfate 0.2928%, N,N'-methylenebisacrylamide 0.0029% and the balance being distilled water by mass percentage;

[0115] Step (2) is the same as that in Example 1.

[0116] Comparative Example 7

[0117] Preparation of the polymer hydrogel matrix is carried out as follows:

[0118] (1) Weigh acrylamide 11.6276%, xanthan gum 0.8721%, ammonium persulfate 0.2907%, N,N'-methylenebisacrylamide 0.0029% and the balance being distilled water by mass percentage;

[0119] Step (2) is the same as that in Example 1.

[0120] Comparative Example 8

[0121] Preparation of the polymer hydrogel matrix is carried out as follows:

[0122] (1) Weigh acrylamide 11.5771%, xanthan gum 1.3024%, ammonium persulfate 0.2894%, N,N'-methylenebisacrylamide 0.0029% and the balance being distilled water by mass percentage;

[0123] Step (2) is the same as that in Example 1.

[0124] Comparative Example 9

[0125] Preparation of the polymer hydrogel matrix is carried out as follows:

[0126] (1) Weigh acrylamide 16.4264%, xanthan gum 0.8213%, ammonium persulfate 0.6160%, N,N'-methylenebisacrylamide 0.0041% and the balance being distilled water by mass percentage;

[0127] Step (2) is the same as that in Example 1.

[0128] Comparative Example 10

[0129] Preparation of the polymer hydrogel matrix is carried out as follows:

[0130] (1) Weigh acrylamide 9.0190%, xanthan gum 0.4509%, ammonium persulfate 0.3382%, N,N'-methylenebisacrylamide 0.0023% and the balance being distilled water by mass percentage;

[0131] Step (2) is the same as that in Example 1.

[0132] Test Example 1

[0133] The tensile properties of the polymer hydrogel matrices prepared in Examples 1-17 and Comparative Examples 1-10 were tested. The tensile property test was carried out on a rubber tensile testing machine (ZQ-990LA). The tensile specimens referred to Type 3 dumbbell-shaped specimens in GB / T 528-2009. The test parameters included: a 5 kg sensor, a gauge length of 20 mm, running at a speed of 40 mm / min, and using dumbbell-shaped double-headed clamp measurement (the measuring instrument was Zhiqu ZQ-990LB). The test results are shown in Table 1.

[0134] Table 1

[0135]

[0136]

[0137] As can be seen from Table 1, the mass ratio of acrylamide, xanthan gum, ammonium persulfate, N,N'-methylenebisacrylamide and distilled water affects the tensile properties of the polymer hydrogel matrix. The tensile properties of Examples 1-17 are better than those of Comparative Examples 1-10. And the tensile properties of the conductive polymer hydrogels formed after adding lithium salts are also affected by the tensile properties of the polymer hydrogel matrix. Among Examples 1-17, the polymer hydrogel matrix prepared in Example 15 has the best tensile properties. Therefore, based on the preparation conditions of Example 15, the preparation of conductive polymer hydrogels with high tensile and self-healing properties was further carried out.

[0138] Example 18

[0139] A conductive polymer hydrogel with high tensile and self-healing properties is prepared as follows:

[0140] (1) By mass percentage, weigh 11.6443% of acrylamide, 0.5822% of xanthan gum, 0.4367% of ammonium persulfate, 0.0044% of N,N'-methylenebisacrylamide and the balance of distilled water; and weigh lithium chloride according to the concentration of lithium chloride in the mixed system composed of acrylamide, xanthan gum, ammonium persulfate, N,N'-methylenebisacrylamide, lithium chloride and distilled water being 1 mol / L.

[0141] (2) Mix acrylamide, xanthan gum, N,N'-methylenebisacrylamide, lithium salt and distilled water in a beaker. First, stir evenly with a glass rod, then stir with a magnetic stirrer for 30 min, and pass nitrogen to remove oxygen for 30 min. Then add ammonium persulfate as the initiator, and centrifuge at low speed in a low-speed centrifuge to remove bubbles. Then place the mixed solution in a water bath and heat it to 65 °C and keep it warm for reaction for 2 h. After the reaction, take out the sample to obtain a conductive polymer hydrogel with high tensile and self-healing properties.

[0142] Example 19

[0143] Same as Example 18, except that the concentration of lithium chloride in the mixed system composed of acrylamide, xanthan gum, ammonium persulfate, N,N'-methylenebisacrylamide, lithium chloride and distilled water is 2 mol / L.

[0144] Example 20

[0145] Same as Example 18, except that the concentration of lithium chloride in the mixed system composed of acrylamide, xanthan gum, ammonium persulfate, N,N'-methylenebisacrylamide, lithium chloride and distilled water is 3 mol / L.

[0146] Example 21

[0147] Same as Example 18, except that the concentration of lithium chloride in the mixed system composed of acrylamide, xanthan gum, ammonium persulfate, N,N'-methylenebisacrylamide, lithium chloride and distilled water is 4 mol / L.

[0148] Example 22

[0149] Same as Example 18, except that the concentration of lithium chloride in the mixed system composed of acrylamide, xanthan gum, ammonium persulfate, N,N'-methylenebisacrylamide, lithium chloride and distilled water is 5 mol / L.

[0150] Example 23

[0151] Same as Example 18, except that the concentration of lithium chloride in the mixed system composed of acrylamide, xanthan gum, ammonium persulfate, N,N'-methylenebisacrylamide, lithium chloride and distilled water is 6 mol / L.

[0152] Test Example 2

[0153] Structure and performance characterization

[0154] (1) Infrared spectrum analysis

[0155] Figure 1 For the conductive polymer hydrogel with high tensile and self-healing properties prepared in Example 19 (i.e., PAM / XG / Li +Infrared spectrum of the DN hydrogel, no stretching vibration absorption peak of the C═C double bond appears at 1695 and 1630 cm -1 This indicates that the vinyl monomers such as acrylamide and N,N'-methylenebisacrylamide have fully polymerized; the strong absorption peak at 3378.76 cm -1 is the characteristic absorption peak of the N-H stretching vibration of the primary amide (-NH2) and the stretching vibration absorption peak of -OH in the polymer; the absorption peak at 3186 cm -1 is the characteristic absorption peak of the N-H stretching vibration of the secondary amide (-NH) in the polymer; the absorption peak at 2932.98 cm -1 is the characteristic absorption peak of the C-H stretching vibration of the methylene (-CH2-) in the polymer; the absorption peaks at 2363.70 and 2313.25 cm -1 are the characteristic absorption peaks of the C-H stretching vibration in xanthan gum; the absorption peak at 1430.72 cm -1 is the characteristic absorption peak of the C-H scissoring bending vibration of the methylene (-CH2-) and the stretching vibration characteristic absorption peak of the carboxyl group; the strong absorption peak at 1664.90 cm -1 is the characteristic absorption peak of the C═O stretching vibration of the amide group (-CONH2); the absorption peak at 1118.22 cm -1 is the characteristic absorption peak of the (C-O-C) stretching vibration in xanthan gum; the above infrared peak values include the characteristic absorption peaks of the functional groups of substances such as acrylamide, N,N'-methylenebisacrylamide, and xanthan gum, indicating that the reactants have undergone a polymerization reaction.

[0156] (2) Thermogravimetric (TGA) analysis

[0157] Thermogravimetric analysis was carried out on the conductive polymer hydrogel with high tensile and self-healing properties prepared in Example 19 (i.e., PAM / XG / Li + DN hydrogel). Specifically, the temperature was raised to 900 °C at a rate of 35 °C / min in an N2 atmosphere and then cooled to room temperature. The thermogravimetric spectrum is as Figure 2 shown. It can be seen that the decomposition temperature of the PAM / XG / Li + DN hydrogel is about 365 °C, the weight loss rate is about 65.75%, the initial decomposition temperature is about 255 °C, and the termination decomposition temperature is about 519 °C.

[0158] (3) Electron microscopy analysis

[0159] The PAM / XG / Li prepared in Example 19 + DN hydrogel was freeze-dried after being swollen by absorbing water. Specifically, the hydrogel sample was placed in distilled water, absorbed water until it was swollen to saturation, and then freeze-dried. The scanning electron microscope (SEM) image of the freeze-dried sample is as Figure 3As shown, where (a)-(d) are SEM images at different magnifications. It can be observed from Figure 3 that a uniform network structure can be seen, which contains a large number of pore structures, similar to a layered honeycomb structure. This structure has strong mechanical properties.

[0160] Test Example 3

[0161] Tensile Property Test

[0162] The conductive polymer hydrogels with high tensile and self-healing properties prepared in Examples 19-23 (i.e., PAM / XG / Li + DN hydrogel) and the polymer hydrogel matrix prepared in Example 15 were subjected to tensile property tests using the same test method as in Test Example 1. The results are shown in Table 2.

[0163] Table 2

[0164]

[0165]

[0166] As can be seen from Table 2, the PAM / XG / Li + DN hydrogels prepared in Examples 18-23 have excellent tensile properties.

[0167] Test Example 4

[0168] Cyclic Tensile Property Test

[0169] The PAM / XG / Li + DN hydrogel prepared in Example 19 was subjected to cyclic tensile tests. Specifically, 10 cyclic tensile tests were carried out under a tensile stress of 800%, and the cyclic hysteresis curve was obtained, as Figure 4 shown. It can be seen that there is no large delay between the first and the tenth cycles, indicating its good elasticity and recovery performance. Also, the stress and hysteresis energy of each cycle are weakening. From Figure 4 it can also be seen that the internal network structure of the PAM / XG / Li + DN hydrogel is gradually consumed and weakened, and the ten cycles are almost overlapping, showing the behavior of a typical polymer elastomer and good self-recovery.

[0170] Test Example 5

[0171] Conductive Property Test

[0172] The PAM / XG / Li + DN hydrogel prepared in Example 19 was subjected to conductive property tests. Specifically, using a small light bulb as an indicator light, a circuit was formed with conductive tape, as Figure 5As shown in A. Using the PAM / XG / Li + DN hydrogel as a conductor, connecting the conductive tape, and applying a voltage of 3V, it can be seen from Figure 5 B that the small light bulb is successfully lit, indicating that the PAM / XG / Li + DN hydrogel has good electrical conductivity. Then, the PAM / XG / Li + DN hydrogel is cut. After the hydrogel is cut, the indicator light no longer emits light, as shown in Figure 5 C. Then, pressure is applied to bond the cut PAM / XG / Li + DN hydrogel together. When the PAM / XG / Li + DN hydrogel is reassembled again, the indicator light is lit again, as shown in Figure 5 D, proving that the PAM / XG / Li + DN hydrogel has good self-healing performance and electrical conductivity.

[0173] The embodiments described above are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A conductive polymer hydrogel with high tensile and self-healing properties, characterized in that the raw materials include lithium salt at 1-6 mol / L, and the following components by mass percentage: acrylamide 10-12%, xanthan gum 0.5-0.6%, initiator 0.2-0.6%, N,N'-methylenebisacrylamide 0.001-0.01%, and the balance is water.

2. The conductive polymer hydrogel with high tensile and self-healing properties according to claim 1, wherein The initiator is ammonium persulfate.

3. The conductive polymer hydrogel with high tensile and self-healing properties according to claim 1, characterized in that, The lithium salt is lithium chloride.

4. The preparation method of the conductive polymer hydrogel with high tensile and self-healing properties according to any one of claims 1-3, characterized in that, It includes the following steps: Mix acrylamide, xanthan gum, initiator, N,N'-methylenebisacrylamide, lithium salt and water, and react under the condition of heat preservation to obtain the conductive polymer hydrogel with high tensile and self-healing properties.

5. The preparation method according to claim 4, characterized in that, The heat preservation temperature is 55-75 °C; the reaction time is 1-5 h.

6. The preparation method according to claim 4, characterized in that, The mixing of acrylamide, xanthan gum, initiator, N,N'-methylenebisacrylamide, lithium salt and water includes: mixing acrylamide, xanthan gum, N,N'-methylenebisacrylamide, lithium salt and water, stirring evenly, passing nitrogen to remove oxygen, then adding the initiator, and removing bubbles.

7. The application of the conductive polymer hydrogel with high tensile and self-healing properties according to any one of claims 1-3 in the preparation of intelligent sensors, electronic skins or energy storage devices.

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