A malleable and self-healing copper cluster-based composite material and its application in flexible sensing.

Abstract

This invention relates to a malleable and self-healing copper cluster-based composite material and its application in flexible sensing. The invention utilizes the dense hydrogen bonds formed between the amide groups on the polymer chains and the glutathione ligands on the surface of the copper clusters to construct a dynamic equilibrium network based on poly(acrylamide-co-N-vinylcarbazole) (PAMCz) and glutathione-stabilized copper nanoclusters (GSH-Cu NCs) through a supramolecular assembly strategy. The dense hydrogen bonds, combined with the π-π stacking effect between the polymer carbazole units, give the copper cluster-based composite material a macroscopically viscoelastic, dough-like characteristic. This unique physical state endows the material with excellent malleability and self-healing properties.

Description

Technical Field

[0001] This invention relates to a malleable and self-healing copper cluster-based composite material and its application in flexible sensing, belonging to the field of new materials. Background Technology

[0002] With the rapid development of flexible electronics, artificial intelligence, and remote medical monitoring, flexible sensors, as a key hub for human-computer interaction interfaces, are gradually becoming one of the cutting-edge directions in new materials research. An ideal flexible sensor should not only possess high-sensitivity signal response performance, but also achieve stable and comfortable conformal fit in complex physiological structures and dynamic motion environments.

[0003] However, the conductive hydrogels and elastomer-based flexible materials currently under extensive research still face significant technical bottlenecks in practical applications. First, traditional elastomer sensors are mostly pre-fabricated films or have fixed geometries, lacking the malleability of clay or dough. This makes it difficult to adapt their shape and perform secondary processing for irregular curved surfaces or personalized wear requirements, greatly limiting their adhesion to irregular surfaces. Second, during long-term use, flexible devices are highly susceptible to physical damage such as mechanical wear, excessive stretching, and even localized cutting. If the material lacks self-healing capabilities, even tiny cracks can interrupt the conductive path, thereby reducing device reliability, shortening service life, and significantly increasing maintenance burden. Furthermore, most self-healing materials at present still require external stimuli (such as heating, ultraviolet irradiation, or chemical initiators) to initiate the repair process, limiting their practical application.

[0004] Therefore, designing and preparing multifunctional composite materials with high plasticity, room temperature self-healing properties and stable electromechanical response has become one of the core issues that urgently need to be addressed in the field of flexible sensing. It has important scientific significance and application prospects for promoting the development of the next generation of wearable health monitoring systems.

[0005] Metal nanoclusters, especially copper nanoclusters (Cu NCs), have become a research hotspot in the field of functional composite materials due to their low cost, environmental friendliness, and excellent optoelectronic properties. However, there is still a lack of systematic design strategies and preparation routes for how to efficiently integrate these nanoclusters into supramolecular network structures with high mechanical dynamic response, thereby constructing intelligent composite material systems that combine deformation sensing capabilities with "dough-like" processability.

[0006] There is an urgent need to develop a copper cluster composite system based on supramolecular dynamic networks to overcome the technical bottlenecks of existing flexible sensing materials in terms of processability, service durability and multifunctional integration, and to provide new ideas for the development of high-performance flexible smart materials. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a malleable and self-healing copper cluster-based composite material and its application in flexible sensing.

[0008] This invention utilizes the dense hydrogen bonds formed between the amide groups on the polymer chain and the glutathione ligands on the surface of the copper clusters to construct a dynamic equilibrium network based on poly(acrylamide-co-N-vinylcarbazole) (PAMCz) and glutathione-stabilized copper nanoclusters (GSH-Cu NCs) through a supramolecular assembly strategy. The dense hydrogen bonds, combined with the π-π stacking interactions between the polymer carbazole units, give the copper cluster-based composite material a macroscopically viscoelastic "dough-like" characteristic. This unique physical state endows the material with excellent plasticity and self-healing properties.

[0009] Meanwhile, the copper nanoclusters distributed in the network structure construct a stable electron transport path, enabling the material to exhibit a sensitive resistive response to mechanical deformation. When the material is bent, stretched, or pressed, the internal conductive pathways deform, causing regular fluctuations in the resistance value, thereby achieving precise capture of human motion signals and providing an innovative material platform for multi-dimensional flexible sensing and monitoring.

[0010] Terminology Explanation:

[0011] GSH-Cu NCs: A copper nanocluster with glutathione as the ligand.

[0012] PAMCz: A polymer containing carbazole units, poly(acrylamide-co-N-vinylcarbazole), with a molecular weight of 26260 g·mol⁻¹. -1 It is easily soluble in water.

[0013] To achieve the above objectives, the present invention adopts the following technical solution:

[0014] In the first aspect, the present invention provides a plastic and self-healing copper cluster-based composite material, wherein the copper cluster-based composite material uses GSH-Cu NCs as acceptors and PAMCz as a solid matrix, and GSH-Cu NCs and PAMCz are obtained by supramolecular self-assembly through solvent induction.

[0015] Secondly, the present invention provides a method for preparing the above-mentioned malleable and self-healing copper cluster-based composite material, comprising the following steps:

[0016] PAMCz powder and GSH-Cu NCs powder were dissolved and mixed evenly in water. Then DMF was added and homogenized to obtain a mixture. The mixture was kept at a constant temperature and the solid was separated to obtain a plastic and self-healing copper cluster-based composite material.

[0017] According to a preferred embodiment of the present invention, the concentration of GSH-Cu NCs in the mixture is 5–40 mg·mL.-1 .

[0018] According to a preferred embodiment of the present invention, the concentration of PAMCz in the mixture is 50–150 mg·mL. -1 .

[0019] According to a preferred embodiment of the present invention, the volume ratio of water to DMF is (0.2-0.8):(1-2).

[0020] According to a preferred embodiment of the present invention, the homogenization time is 1 to 5 minutes.

[0021] According to a preferred embodiment of the present invention, the constant temperature settling is performed by settling in a constant temperature chamber at 20 °C for 8 hours.

[0022] According to a preferred embodiment of the present invention, the GSH-Cu NCs powder is prepared by the following method:

[0023] Glutathione (GSH) aqueous solution was added to copper sulfate (CuSO4) aqueous solution, and the solution changed from transparent to white suspension. Alkaline solution was added dropwise to adjust the pH of the system to 4-5, and the mixture was stirred vigorously to obtain GSH-CuNCs aqueous solution. GSH-CuNCs powder was obtained by freeze drying.

[0024] According to a preferred embodiment of the present invention, the concentration of the GSH aqueous solution is 20–100 mg·mL. -1 The concentration of CuSO4 aqueous solution is 5-20 mmol·L⁻¹ -1 .

[0025] Most preferably, the concentration of the GSH aqueous solution is 50 mg·mL. -1 The concentration of the CuSO4 aqueous solution is 10 mmol·L⁻¹. -1 .

[0026] According to a preferred embodiment of the present invention, the mixing volume ratio of GSH aqueous solution to CuSO4 aqueous solution is 1:1.

[0027] According to a preferred embodiment of the present invention, the alkaline solution has a concentration of 1 mol·L⁻¹. -1 NaOH aqueous solution or concentration 1 mol·L -1 Aqueous solution of KOH.

[0028] According to a preferred embodiment of the present invention, the pH value of the system is adjusted to 4.0 by adding an alkaline solution dropwise.

[0029] According to a preferred embodiment of the present invention, the stirring speed is 400-500 rpm and the stirring time is 1 hour.

[0030] According to a preferred embodiment of the present invention, the freeze-drying temperature is -60°C and the freeze-drying time is 24 hours.

[0031] According to a preferred embodiment of the present invention, the PAMCz powder is prepared by the following method:

[0032] Under argon protection, acrylamide, azobisisobutyronitrile, and vinylcarbazole were dissolved in tetrahydrofuran, heated, and stirred to obtain a white precipitate. The precipitate was washed successively with petroleum ether, dichloromethane, and acetone. After washing, it was dissolved in deionized water and dialyzed for 72 hours using a dialysis bag with a molecular weight cutoff of 1000 Da. The dialysate was then freeze-dried to obtain PAMCz powder.

[0033] According to a preferred embodiment of the present invention, the mass ratio of acrylamide, azobisisobutyronitrile, and vinylcarbazole is 3550:83:96.5.

[0034] According to a preferred embodiment of the present invention, the mass-volume ratio of acrylamide to tetrahydrofuran is 3.55 g: 25 mL.

[0035] According to a preferred embodiment of the present invention, the heating temperature is 55 °C.

[0036] According to a preferred embodiment of the present invention, the freeze-drying temperature is -60°C and the freeze-drying time is 24 hours.

[0037] The copper cluster-based composite material of the present invention has "dough-like" viscoelastic characteristics, which endows the material with excellent plasticity and self-healing properties.

[0038] Thirdly, the present invention provides the application of the above-mentioned malleable and self-healing copper cluster-based composite material in flexible sensing.

[0039] According to a preferred embodiment of the present invention, the copper cluster-based composite material is shaped into different shapes by kneading, stretching or molding, and then conductive copper wires are connected to both ends of the material to prepare a flexible strain sensor.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] 1. This invention avoids the high cost of precious metal nanomaterials such as gold and silver, and selects copper, which is abundant, inexpensive and environmentally friendly, as the building block.

[0042] 2. This invention employs a mixed solvent-induced assembly strategy, achieving uniform dispersion and assembly of nanoclusters in a polymer matrix through simple physical homogenization. This method avoids complex chemical grafting reactions, simplifies the preparation process, and requires no sophisticated equipment.

[0043] 3. The composite material prepared by this invention exhibits a unique "dough-like" physical characteristic on a macroscopic scale. This property allows the sensor to no longer be limited to a specific geometry, and it can be arbitrarily kneaded, stretched, or molded. This superior conformal processing capability greatly expands the application scenarios of flexible electronic devices, enabling seamless bonding of sensors with complex irregular surfaces.

[0044] 4. This invention utilizes the highly dynamic reversible non-covalent bonds in supramolecular networks to endow the material with significant self-healing properties. The repair process requires no heating, ultraviolet light irradiation, or the addition of additives, significantly reducing the maintenance cost of the device and ensuring the highly reliable operation of the flexible sensing system in complex environments.

[0045] 5. This invention constructs a highly stable piezoresistive sensing mechanism by optimizing the dispersion state of copper nanoclusters in a supramolecular network. Attached Figure Description

[0046] Figure 1 The Fourier transform infrared (FTIR) spectrum of GSH-Cu NCs obtained in Example 1.

[0047] Figure 2 Electrospray ionization mass spectrometry (ESI-MS) of GSH-Cu NCs obtained in Example 1.

[0048] Figure 3 The first image shows a photograph of the copper cluster-based composite material prepared in Example 1 under sunlight; a is a photograph before the solid was separated; b is a macroscopic photograph of the solid obtained after separation.

[0049] Figure 4 The image shows the FTIR spectrum of the copper cluster-based composite material prepared in Example 1.

[0050] Figure 5 The following are rheological property curves of the copper cluster-based composite material prepared in Example 1: a is the stress-strain curve (f = 1.0 Hz); b is the frequency scan curve (τ = 10 Pa); c is the curve of shear viscosity as a function of shear rate.

[0051] Figure 6 This is a photograph showing the plasticity of the copper cluster-based composite material obtained in Example 2.

[0052] Figure 7 This is a photograph showing the self-healing properties of the copper cluster-based composite material obtained in Example 3.

[0053] Figure 8 The first image shows a photograph of the copper cluster-based composite material obtained in Example 4 under sunlight; a is a photograph before the solid was separated; b is a macroscopic photograph of the solid obtained after separation.

[0054] Figure 9 The first image shows a photograph of the copper cluster-based composite material obtained in Example 5 under sunlight; a is a photograph before the solid was separated; b is a macroscopic photograph of the solid obtained after separation.

[0055] Figure 10 The first image shows a photograph of the copper cluster-based composite material obtained in Example 6 under sunlight; a is a photograph before the solid was separated; b is a macroscopic photograph of the solid obtained after separation.

[0056] Figure 11 The graph shows a comparison of the electrical conductivity of copper cluster-based composite materials prepared at different GSH-Cu NCs concentrations. The inset shows a photograph of the luminescence of the copper cluster-based composite material in a circuit.

[0057] Figure 12 The illustration shows the strain response performance test of the copper cluster-based composite material prepared in Example 1. The inset is a schematic diagram of finger bending at different bending angles of 0°, 45°, and 90°. Specific implementation methods

[0058] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0059] All raw materials used in the examples were conventional raw materials and commercially available products. CuSO4 was purchased from Tianjin Kemei Chemical Reagent Co., Ltd., L-GSH, acrylamide, azobisisobutyronitrile and vinylcarbazole were purchased from Sinopharm Chemical Reagent Co., Ltd., NaOH was purchased from Anhui Zesheng Technology Co., Ltd., and DMF was purchased from Shanghai Maclean Biochemical Technology Co., Ltd. No further purification was performed before use.

[0060] Example 1

[0061] The preparation method of copper cluster-based composite materials with malleable and self-healing properties includes the following steps:

[0062] (1) Synthesis of GSH-Cu NCs

[0063] Add 5.0 mL of glutathione (GSH) aqueous solution (50 mg / mL) -1 ) and 5.0 mL of copper sulfate (CuSO4) aqueous solution (10 mmol·L⁻¹) -1 The mixture was initially a white suspension, and then 1 mol·L⁻¹ was slowly added dropwise. -1The pH of the system was adjusted to 4.0 using a sodium hydroxide (NaOH) solution. During this process, the white suspension gradually turned into a transparent pale yellow. The reaction was stirred at 450 rpm for 1 hour to obtain an aqueous solution of the initial product. Finally, the solution was freeze-dried at -60 ℃ for 24 hours to obtain GSH-Cu NCs solid powder.

[0064] The FTIR spectra of the obtained GSH-Cu NCs are as follows Figure 1 As shown. By Figure 1 It is known that the ligand glutathione is linked to the copper nucleus via Cu-S.

[0065] The electrospray ionization mass spectra of the obtained GSH-Cu NCs are as follows: Figure 2 As shown. By Figure 2 It can be seen that the main component of GSH-Cu NCs is Cu5GSH3.

[0066] (2) Synthesis of PAMCz

[0067] Under a high-purity inert argon atmosphere, 3.55 g of acrylamide, 96.5 mg of vinylcarbazole, and 83 mg of azobisisobutyronitrile (AIB) were dissolved in 25 mL of tetrahydrofuran (THF). The reaction system was heated to 55 °C and stirred at this temperature for 16 hours. After the reaction was complete, a white polymer precipitate was observed to form. The precipitate was then washed alternately with petroleum ether, dichloromethane, and acetone to remove residual monomers. The washed solid was dissolved in deionized water and placed in a dialysis bag with a molecular weight cutoff of 1000 Da for continuous dialysis purification for 72 hours. The dialysis solution was freeze-dried at -60 °C for 24 hours to obtain highly purified PAMCz powder.

[0068] (3) Preparation of copper cluster-based composite materials

[0069] 200 mg of PAMCz solid and 80 mg of GSH-Cu NCs powder were dissolved together in 0.6 mL of deionized water and mixed thoroughly. Then, 1.4 mL of N,N-dimethylformamide (DMF) was rapidly injected into the aqueous system, and homogenization was immediately performed for 1 min. After homogenization, the mixture was transferred to a 20 °C incubator and allowed to stand for 8 hours to separate the solids. A photograph of the sample before solid separation is shown below. Figure 3 In section a, the separated solid is the copper cluster-based composite material; see the photograph for details. Figure 3 In section b, the conductivity of the solid was tested, and the conductivity was 33.3 mS·m. -1 The electrical conductivity of the composite material is higher than that of the pure PAMCz material (2.59 mS·m). -1 It increased by 12.9 times.

[0070] In this embodiment, the FTIR spectrum of the copper cluster-based composite material is as follows: Figure 4 As shown. By Figure 4 This indicates that there is a hydrogen bond between the glutathione (GSH) ligand on the surface of the copper cluster and the amide group of the PAMCz matrix, and the formation of the copper cluster-based composite material is hydrogen bond driven.

[0071] The rheological property curves of the copper cluster-based composite material obtained in this embodiment are shown in the figure below. Figure 5 As shown. By Figure 5 It can be seen that the storage modulus (G') of the copper cluster-based composite material is always significantly higher than its loss modulus (G"), which ensures that the material has sufficient self-support (does not flow or collapse after being kneaded) and retains a certain degree of viscoelasticity (easy to stretch and deform).

[0072] Example 2

[0073] The preparation method is the same as that described in Example 1, except that:

[0074] Step (1) Synthesis of GSH-Cu NCs

[0075] Add 5.0 mL of glutathione (GSH) aqueous solution (50 mg / mL) -1 ) and 5.0 mL of copper sulfate (CuSO4) aqueous solution (10 mmol·L⁻¹) -1 The mixture was initially a white suspension, and then 1 mol·L⁻¹ was slowly added dropwise. -1 A potassium hydroxide (KOH) solution was used to adjust the pH of the system to 4.0. During this process, the white suspension gradually turned into a transparent pale yellow. The mixture was stirred at 400-500 rpm for 1 hour to obtain an aqueous solution of the initial product. Finally, the solution was freeze-dried at -60 ℃ for 24 hours to obtain GSH-Cu NCs solid powder.

[0076] The rest is carried out according to Example 1.

[0077] The plasticity photographs of the copper cluster-based composite material obtained in this embodiment are as follows: Figure 6 As shown, through Figure 6 It can be seen that copper cluster-based composite materials can change into any shape, indicating that they have strong plasticity.

[0078] Example 3

[0079] The preparation method is the same as that described in Example 1, except that:

[0080] Step (3): Homogenization time is 3 min, and other steps are performed as in Example 1.

[0081] The self-healing properties of the copper cluster-based composite material obtained in this embodiment are shown in the following photographs. Figure 7 As shown, through Figure 7 It can be seen that the two pieces of copper cluster-based composite material, when cut apart and stacked together, can heal together after 2 hours, indicating that they have self-healing properties.

[0082] Example 4

[0083] The preparation method is the same as that described in Example 1, except that:

[0084] In step (3), 200 mg of PAMCz solid and 60 mg of GSH-Cu NCs powder were dissolved together in 0.6 mL of deionized water and mixed thoroughly. Then, 1.4 mL of DMF was rapidly injected into the aqueous system, and homogenization was immediately initiated using a homogenizer for 3 min. After homogenization, the mixture was transferred to a 20 ℃ incubator and allowed to stand for 8 hours to separate the solids.

[0085] See the actual photos of the object before solid separation. Figure 8 In section a, the separated solid is the copper cluster-based composite material; see the photograph for details. Figure 8 In section b, the conductivity of the solid was tested, and the conductivity was 35.6 mS·m. -1 The electrical conductivity of the composite material is higher than that of the pure PAMCz material (2.59 mS·m). -1 It increased by 13.7 times.

[0086] Example 5

[0087] The preparation method is the same as that described in Example 1, except that:

[0088] In step (3), 200 mg of PAMCz solid and 40 mg of GSH-Cu NCs powder were dissolved together in 0.6 mL of deionized water and mixed thoroughly. Then, 1.4 mL of DMF was rapidly injected into the aqueous system, and homogenization was immediately initiated using a homogenizer for 3 min. After homogenization, the mixture was transferred to a 20 ℃ incubator and allowed to stand for 8 hours to separate the solids.

[0089] See the actual photos of the object before solid separation. Figure 9 In section a, the separated solid is the copper cluster-based composite material; see the photograph for details. Figure 9 In section b, the conductivity of the solid was tested, and the conductivity was 20.1 mS·m. -1 The electrical conductivity of the composite material is higher than that of the pure PAMCz material (2.59 mS·m). -1 It increased by 7.8 times.

[0090] Example 6

[0091] The preparation method is the same as that described in Example 1, except that:

[0092] In step (3), 200 mg of PAMCz solid and 20 mg of GSH-Cu NCs powder were dissolved together in 0.6 mL of deionized water and mixed thoroughly. Then, 1.4 mL of DMF was rapidly injected into the aqueous system, and homogenization was immediately initiated using a homogenizer for 3 min. After homogenization, the mixture was transferred to a 20 °C incubator and allowed to stand for 8 hours to separate the solids.

[0093] See the actual photos of the object before solid separation. Figure 10 In section a, the separated solid is the copper cluster-based composite material; see the photograph for details. Figure 10 In section b, the conductivity of the solid was tested, and the conductivity was 12.3 mS·m. -1 The electrical conductivity of the composite material is higher than that of the pure PAMCz material (2.59 mS·m). -1 It increased by 4.7 times.

[0094] The electrical conductivity of copper cluster-based composite materials prepared at different GSH-Cu NCs concentrations is as follows: Figure 11 As shown, through Figure 11 It can be seen that the difference in material conductivity originates from the variation in the distribution density of GSH-CuNCs in the PAMCz dynamic network. With the increase of GSH-CuNCs concentration, the spacing between copper clusters in the system decreases to the tunneling transition range and eventually forms a continuous conductive pathway throughout the entire system through supramolecular assembly. This concentration-adjustable electromechanical response characteristic provides a physical basis for customizing the sensitivity of sensors for different deformation ranges.

[0095] Example 7

[0096] Applications of malleable and self-healing copper cluster-based composite materials in flexible sensing:

[0097] The copper cluster-based composite material obtained in Example 1 was used to shape it into a rectangular strip (approximately 20 mm × 10 mm × 2 mm) by taking advantage of its excellent plasticity. Conductive copper wires were connected to both ends of the material as electrodes to fabricate a flexible strain sensor.

[0098] The strain response performance of the sensor was tested as follows: Figure 12 As shown, the sensor was fixed to a finger and subjected to a cyclic bending experiment. The results showed that within the bending angle range of 0°-90°, the relative resistance change (ΔR / R0) of the sensor exhibited a good linear relationship with the bending angle, proving that the composite material has significant application value in the fields of human motion monitoring and flexible electronic skin.

[0099] In summary, this invention successfully prepared a copper cluster-based composite material integrating plasticity, room temperature self-healing, and sensitive sensing through a mixed solvent-induced self-assembly strategy. Utilizing the dense hydrogen bonds formed between the PAMCz polymer network and the surface ligands of GSH-Cu NCs, as well as the π-π stacking effect of carbazole groups, a highly dynamic and stable supramolecular network was constructed at the microscopic level. This material exhibits "dough-like" processing properties on a macroscopic scale, capable of conforming to various irregular surfaces, while also possessing stable electrical conductivity and a linear electrical response to mechanical deformation. This invention effectively solves the problems of difficult processing, inability to repair damage, and low functional integration in traditional flexible sensors, and has significant application value and broad market prospects in the fields of smart electronic skin, human health monitoring, and human-computer interaction.

Claims

1. A plastic and self-healing copper cluster-based composite material, wherein the copper cluster-based composite material is composed of GSH-Cu NCs as components and PAMCz as a solid matrix, and GSH-Cu NCs and PAMCz are obtained by supramolecular self-assembly through solvent induction.

2. The method for preparing the malleable and self-healing copper cluster-based composite material according to claim 1, comprising the following steps: PAMCz powder and GSH-Cu NCs powder were dissolved and mixed evenly in water. Then DMF was added and homogenized to obtain a mixture. The mixture was kept at a constant temperature and the solid was separated to obtain a plastic and self-healing copper cluster-based composite material.

3. The preparation method according to claim 2, characterized in that, The concentration of GSH-Cu NCs in the mixture was 5–40 mg·mL. -1 The concentration of PAMCz in the mixture was 50–150 mg / mL. -1 .

4. The preparation method according to claim 2, characterized in that, The volume ratio of water to DMF was (0.2-0.8):(1-2), the homogenization time was 1-5 min, and the constant temperature standing was 8 hours in a constant temperature chamber at 20 ℃.

5. The preparation method according to claim 2, characterized in that, GSH-Cu NCs powder is prepared by the following method: Glutathione (GSH) aqueous solution was added to copper sulfate (CuSO4) aqueous solution, and the solution changed from transparent to white suspension. Alkaline solution was added dropwise to adjust the pH of the system to 4-5, and the mixture was stirred vigorously to obtain GSH-Cu NCs aqueous solution. GSH-Cu NCs powder was obtained by freeze drying.

6. The preparation method according to claim 5, characterized in that, The concentration of GSH aqueous solution is 20–100 mg / mL. -1 The concentration of CuSO4 aqueous solution is 5-20 mmol·L⁻¹ -1 The volume ratio of GSH aqueous solution to CuSO4 aqueous solution is 1:1, and the alkaline solution has a concentration of 1 mol·L⁻¹. -1 NaOH aqueous solution or concentration 1 mol·L -1 The KOH aqueous solution was stirred vigorously at a speed of 400-500 rpm for 1 hour, and the freeze-drying temperature was -60℃ for 24 hours.

7. The preparation method according to claim 2, characterized in that, PAMCz powder was prepared by the following method: Under argon protection, acrylamide, azobisisobutyronitrile, and vinylcarbazole were dissolved in tetrahydrofuran, heated, and stirred to obtain a white precipitate. The precipitate was washed successively with petroleum ether, dichloromethane, and acetone. After washing, it was dissolved in deionized water and dialyzed for 72 hours using a dialysis bag with a molecular weight cutoff of 1000 Da. The dialysate was then freeze-dried to obtain PAMCz solid.

8. The preparation method according to claim 7, characterized in that, The mass ratio of acrylamide, azobisisobutyronitrile, and vinylcarbazole was 3550:83:96.5, the mass ratio of acrylamide to tetrahydrofuran was 3.55 g:25 mL, the heating temperature was 55 ℃, the freeze-drying temperature was -60 ℃, and the freeze-drying time was 24 hours.

9. Application of malleable and self-healing copper cluster-based composite materials in flexible sensing.

10. The application according to claim 9, characterized in that, The copper cluster-based composite material is shaped into different shapes by kneading, stretching, or molding, and then conductive copper wires are connected to both ends of the material to prepare a flexible strain sensor.

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