Elastic conductive fiber, elastic conductive fiber with self-enhanced electrical properties at high and low temperatures, and preparation method and application thereof

Abstract

The application relates to an elastic conductive fiber, an elastic conductive fiber with self-enhanced electrical properties at high and low temperatures, and a preparation method and application thereof. The elastic conductive fiber comprises an elastomer and a conductive filler; wherein the conductive filler is a solid conductive filler and a conductive liquid. The preparation process has low requirements on experimental equipment, materials and processing environment, is simple in process and low in cost, has high forming efficiency of the elastic conductive fiber, great potential for large-scale production, and is convenient for realizing performance regulation and large-scale production of the material.

Description

Technical Field

[0001] The present invention belongs to the field of conductive fibers, and in particular relates to an elastic conductive fiber, an elastic conductive fiber with autonomously enhanced electrical properties at high and low temperatures, and a preparation method and application thereof. Background Art

[0002] With the development of materials science and electronic technology, the trend of miniaturization of electronic devices has promoted the rapid development of wearable electronic products. Today, electronic textiles are one of the most promising wearable electronic products, relying on conductive fibers or yarns to achieve conductivity, signal transmission and information exchange. Fibers, as a basic unit of wearable devices, are lightweight, flexible, easy to integrate and highly adaptable, and have good prospects in the application of electronic fabrics / textiles and wearable electronic products. Compared with two-dimensional and three-dimensional materials, elastic conductive fibers still face great challenges in balancing conductivity and stretchability due to their thinner diameter, especially in extreme temperature conditions of low or high temperatures. Therefore, it is of great significance to develop an elastic conductive fiber that can withstand high and low temperature environments and has stable electrical properties.

[0003] Elastic conductive fibers with the ability to actively enhance electrical properties in extreme environments such as high and low temperatures refer to fiber materials that possess both mechanical deformation and electrical conductivity. Their conductivity can be autonomously enhanced under high and low temperature conditions, and their resistance stability is also improved under high and low temperature conditions. As electrode materials, they are an important component of flexible electronic devices and wearable devices. They are suitable for various electronic devices such as nanogenerators, batteries, supercapacitors, sensors, actuators, heaters, soft robots, etc., serving applications such as energy management, sensing detection, physiological monitoring, electronic skin, and intelligent biointerfaces. Especially in the continuous pursuit of seamless integration of electronic devices with clothing / human bodies and improved wearing comfort, high-performance fiber electrodes play an increasingly important role and show great application potential in the future of flexible and wearable electronics. However, traditional metal, inorganic / organic conductive fibers have difficulty balancing electrical and mechanical properties and stability in cold and hot environments, which limits their application in the fields of smart fibers / fabrics, flexible electronics, and wearable technologies.

[0004] Traditional technologies often use a single conductive material as a filler or surface decoration to achieve the conductive properties of fiber materials; polymers or adhesives are then used to enhance the mechanical stability of the conductive material. Regarding the aforementioned research, while these methods can achieve fiber materials with a certain degree of conductivity and deformability, they still face significant challenges in balancing electrical and mechanical properties. In particular, the fibers struggle to adapt to high and low temperature environments, significantly limiting their application in deformable wearable electronic devices and their suitability for extreme scenarios. Summary of the Invention

[0005] In view of the defects of the prior art, the technical problem to be solved by the present application is to provide an elastic conductive fiber and a preparation method and application thereof, in particular, to provide an elastic conductive fiber with self-enhanced electrical properties at high and low temperatures and a preparation method and application thereof.

[0006] The elastic conductive fiber of the present application comprises an elastomer and a conductive filler; wherein the conductive filler is a solid conductive filler and a conductive liquid, and the mass ratio of the conductive liquid to the solid conductive filler is 1:100 to 10:1.

[0007] Preferably, the elastic conductive fiber is obtained by wet spinning using the elastomer and the conductive filler as raw materials.

[0008] Preferably, in the conductive filler, the average size of the solid conductive filler is 1 to 15 microns, and the median particle size of the conductive liquid is 500 nm to 100 microns.

[0009] The average size of the solid conductive filler is specifically: if the solid conductive filler is a micro-nano sheet, the average size refers to the average length; if the solid conductive filler is a micro-nano particle, the average size refers to the average particle size; if the solid conductive filler is a nanowire, the average size refers to the average length; and if the solid conductive filler is a nanorod, the average size refers to the average length.

[0010] Further preferably, the mass ratio of the conductive liquid to the solid conductive filler is 1:5 to 5:1; the average size of the solid conductive filler is 1 to 10 microns; and the median particle size of the conductive liquid is 10 to 60 microns.

[0011] Preferably, the mass ratio of the conductive filler to the elastomer is 1:100 to 30:1.

[0012] Further preferably, the mass ratio of the conductive filler to the elastomer is 1:10 to 20:1.

[0013] Preferably, the solid conductive filler comprises one or more of a conductive polymer, MXene, a metal micro-nano material, and a carbon-based micro-nano material; wherein the metal micro-nano material comprises a metal micro-nano particle, a metal micro-nano sheet, a metal nanowire, and a metal nanorod.

[0014] The conductive liquid comprises one or more of a liquid metal, a liquid metal modifier, an ionic liquid, an ion conductor, and a conductive polymer; wherein the liquid metal is a metal alloy material with low melting point, high conductivity, and liquid state at room temperature.

[0015] Further preferably, the solid conductive filler includes one or more of MXene, silver micro-nanosheets, copper micro-nanosheets, silver nanowires, copper nanowires, silver nanoparticles, silver microspheres, copper microspheres, graphite, carbon black, carbon nanotubes, graphene, graphene oxide, and modifications thereof; the conductive liquid includes a gallium alloy; wherein the gallium alloy includes at least one of a gallium-indium alloy and a gallium-indium-tin alloy.

[0016] Further preferably, the solid conductive filler is a metal micro-nano material, including silver micro-nano sheets, copper micro-nano sheets, silver nanowires, copper nanowires, silver nanoparticles, silver microspheres, and copper microspheres.

[0017] When the fiber is heated, the microphase flow of the polymer molecular segments, the sintering of the metal micro-nanomaterials, and the dynamic compensation of the liquid conductive material create more and tighter conductive pathways within the fiber, thereby autonomously enhancing conductivity within a certain range of high-temperature environments. Simultaneously, at low temperatures, the fiber's elastomer matrix undergoes microscopic contraction, while the liquid metal micro-nanoparticles actively or passively expand at the microscopic level, promoting connectivity between the conductive fillers and enhancing the fiber's conductivity.

[0018] More preferably, the conductive filler comprises a composite of micro-nano silver flakes and gallium-indium liquid alloy.

[0019] Preferably, the elastomer comprises one or more of polyurethane, polydimethylsiloxane, styrene block copolymer (such as styrene ethyl butylene styrene), ethylene-vinyl acetate copolymer, and isoprene copolymer.

[0020] Further preferably, the elastomer is polyurethane, which has excellent elasticity and good fiber-forming properties. As an elastic matrix, it can well wrap and fix the conductive filler, providing a stable conductive path and deformation ability.

[0021] Preferably, the elastic conductive fiber further contains a reinforcing agent; the mass ratio of the reinforcing agent to the elastomer is 1:50 to 5:1.

[0022] Further preferably, the mass ratio of the reinforcing agent to the elastomer is 1:30 to 3:1.

[0023] Preferably, the enhancer is an enhancer containing active functional groups.

[0024] Preferably, the active functional group-containing enhancer includes one or more of polyacrylic acid, polymethyl methacrylate, polyethyleneimine, and polycaprolactam.

[0025] Furthermore, the conductive filler and reinforcing agent are embedded in the interior and surface of the elastomer.

[0026] The conductive fiber comprises at least one of a single fiber, a yarn, a fiber mat, a fiber film, and a fabric; and the conductive fiber has a diameter of 10 nm to 5 mm.

[0027] More preferably, the conductive fibers have an average diameter of 200 μm to 1 mm.

[0028] A method for preparing an elastic conductive fiber of the present invention comprises:

[0029] The elastomer and solvent are mixed and stirred, a solid conductive filler is added and stirred, a conductive liquid is added and stirred to obtain a spinning solution, the spinning solution is degassed and then spun, solidified and formed, and dried to obtain an elastic conductive fiber;

[0030] Alternatively, the elastomer, reinforcing agent, and solvent are mixed and stirred, a solid conductive filler is added and stirred, a conductive liquid is added and stirred to obtain a spinning solution, the solution is degassed and then spun, solidified and formed, and dried to obtain an elastic conductive fiber.

[0031] Preferably, the solvent includes one or more of water, ethanol, acetone, isopropanol, toluene, tetrahydrofuran, pyridine, N,N-dimethylformamide, and thionyl chloride;

[0032] Preferably, the mass concentration of the elastomer after the elastomer and the solvent are mixed is 5wt% to 70wt%.

[0033] Preferably, the mass concentration of the elastomer after the elastomer, reinforcing agent and solvent are mixed is 5wt% to 70wt%.

[0034] Preferably, the spinning is at least one of dry spinning, wet spinning, microfluidic spinning, and electrospinning;

[0035] More preferably, the spinning method is wet spinning, the needle gauge used in the wet spinning is 15 to 21G, and the spinning solution propulsion speed is 1 to 80 ml h -1 .

[0036] Preferably, the stirring temperature for mixing the elastomer and solvent or the elastomer, reinforcing agent and solvent is 20-150°C, the stirring time is 1-3 hours, the solid conductive filler is added, the stirring time is 5-30 hours, the conductive liquid is added, the stirring time is 5-30 hours, and the spinning solution is obtained.

[0037] Preferably, the conductive liquid is a conductive liquid that has been dispersed, wherein the dispersion treatment method includes one or more of mechanical stirring, high-speed shearing, and ultrasonic treatment.

[0038] More preferably, the rotation speed of the high-speed shearing is 1000 to 15000 rpm, the processing time is 1 to 10 minutes, and the ultrasonic processing time is 1 to 30 minutes.

[0039] The present invention provides an elastic conductive fiber with autonomously enhanced electrical properties at high and low temperatures. The elastic conductive fiber with autonomously enhanced electrical properties at high and low temperatures is obtained by subjecting the elastic conductive fiber to static high-temperature, dynamic cyclic stretching at high temperature, or dynamic cyclic stretching at low temperature.

[0040] Preferably, the high temperature is 20 to 300° C.; the low temperature is -200 to 0° C.; the treatment time is 1 to 100 minutes; and the dynamic cyclic stretching strain is 1% to 300%.

[0041] Further preferably, the static high temperature treatment temperature is 20-250°C and the time is 1-100 min;

[0042] More preferably, the dynamic cyclic stretching temperature at high temperature is 50-150° C., the time is 1-100 min, the dynamic cyclic stretching strain is 1%-300%, and the number of cycles is 1-50;

[0043] More preferably, the dynamic cyclic stretching temperature at low temperature is -20 to 0° C., the time is 1 to 100 min, the dynamic cyclic stretching strain is 1% to 300%, and the number of cycles is 1 to 50.

[0044] The elastic conductive fiber of the present invention is used in the fields of optoelectronics, information, energy, medical treatment or national defense.

[0045] The invention discloses an elastic conductive fiber with autonomously enhanced electrical properties at high and low temperatures, and its application in optoelectronics, information, energy, medical treatment or national defense fields.

[0046] Preferably, the applications in the optoelectronic field include lighting, display, touch control, or human-computer interaction applications.

[0047] Preferably, the applications in the information field include sensing, information encryption, information protection or information interaction equipment.

[0048] Preferably, the energy field application includes light-heat conversion, heating or thermal energy management equipment.

[0049] Preferably, the application in the medical field includes flexible or wearable medical devices.

[0050] Preferably, the applications in the field of national defense include simultaneous interpretation of data and energy, and applications in the field of aerospace.

[0051] This invention develops a composite elastic conductive material that utilizes a common spinning process to achieve a one-step formation of elastic conductive fibers. Specifically, the conductive filler is effectively drawn and aligned during the spinning process, embedded within the elastomer matrix or partially exposed on the fiber surface. The elastomer matrix effectively protects the conductive filler, maintaining the integrity of the conductive pathway to the greatest extent possible. The reinforcing agent provides sufficient active functional groups, strengthening the connection between the elastomer and the conductive material, as well as between different conductive materials. This allows the fiber to maintain relatively stable conductivity or electrical responsiveness even under large deformations.

[0052] The present invention can use a liquid conductive material of appropriate size to compound a solid conductive filler of appropriate size. The fluidity and large deformation characteristics of the liquid conductive material can effectively bridge the solid conductive filler and dynamically compensate for the breakpoints between the solid conductive fillers under large deformation conditions, so that the conductive fiber can adapt to large mechanical deformation and maintain relatively stable conductivity or stable electrical recovery.

[0053] At the same time, when the fiber is heated, the microphase flow of the polymer molecular segments, the dynamic compensation effect of the solid conductive material and the liquid conductive material, form more / tighter conductive paths inside the fiber, and can autonomously enhance the conductivity under a certain range of high temperature environments. At the same time, at low temperatures, the fiber elastomer matrix will shrink microscopically, and the liquid metal particles will actively or passively expand at the microscopic level, promoting the connection between the conductive fillers and enhancing the conductivity of the fiber. At the same time, with the reinforcing agent as a bridge, a more stable hydrogen bond interaction is formed between the solid conductive filler and the liquid conductive filler, as well as between the two and the polymer. In addition, after dynamic cyclic stretching treatment, the liquid conductive material can be better spread out and better connected to the solid conductive material.

[0054] The mechanical deformations involved in the present invention include compression deformation, tensile deformation, bending deformation, and shear deformation. Stable electrical resilience means that the resistance change rate of the fiber remains relatively stable at the same deformation amount. The autonomous maintenance, repair or enhancement of the conductive path means that when the fiber undergoes large mechanical deformation or heat treatment, the polymer molecular chain undergoes microphase movement, and at the same time the conductive liquid filler can flow / deform to adapt to the fiber deformation, or melt / release to adapt to the high temperature environment, to achieve effective bridging or even enhancement of other displacement or breakpoint conductive paths, maintain a relatively stable conductive path and electrical resilience, or autonomously enhance conductivity. At the same time, it also means that the fiber volume will microscopically shrink at low temperatures, and the liquid metal micro-nanoparticles will actively or passively expand, both of which provide more opportunities for better contact of the conductive filler, making the conductive path more stable, improving conductivity, and enhancing the fiber's autonomous adaptability to mechanical deformation.

[0055] Advantages

[0056] The present application realizes the adaptability and coordination between the composite conductive filler and the polymer substrate by regulating the ratio of the composite conductive filler and by introducing a reinforcing agent, and enhances the adaptability of the fiber to mechanical deformation. By regulating the high-temperature and low-temperature treatment mode of the elastic conductive fiber, the electrical, mechanical and electrical performance stability under cold and hot environments can be regulated; by introducing a dynamic compensation mechanism of the conductive path, the self-adaptation and repair of the composite fiber under mechanical deformation can be realized, and the effective balance of electrical and mechanical properties can be achieved, and meanwhile, the self-enhancement of the conductive path under high-temperature and low-temperature environments can be realized, so that the elastic fiber capable of self-maintaining, repairing or enhancing the conductive path under large mechanical deformation or high-temperature and low-temperature environments is obtained.

[0057] Compared with the existing conductive fiber materials, the application of the materials in the field of flexible mechanics, extreme deformation and extreme temperature environment adaptability wearable electronic devices is greatly expanded. The resistance range of the conductive fiber is 1 ohm-10000 ohm, the mechanical deformation amount is 1 %-1000 %, the resistance increase rate of the fiber deformation recoverable is 1 %-2000 %, the resistance reduction rate of the fiber heated is 0.1 %-100 %, and the resistance reduction rate of the fiber cooled is 0.1 %-100 %. The fiber can better balance the conductivity and deformation amount to adapt to the mechanical deformation needs in different application scenarios, and can be applied to the high deformation needs of the electronic devices such as deformation fiber electrode, sensor, heater, energy collector, driver and communication device in multiple temperature scenarios.

[0058] The conductive filler of the present application has a wide selection of materials, can be applied to various elastomer matrix materials, has low requirements for experimental equipment, materials and processing environment, simple process, low cost and easy operation, high forming efficiency of the composite elastic conductive fiber, great potential for large-scale production, and is convenient for realizing performance regulation and large-scale production of the material. BRIEF DESCRIPTION OF DRAWINGS

[0059] Figure 1 is a scanning electron microscope image of the elastic conductive fiber (Example 1) of the present application;

[0060] Figure 2 is a stress-strain curve of the elastic conductive fiber (Example 1) of the present application;

[0061] Figure 3 is a curve of the change of the resistance of the elastic conductive fiber (Example 1) of the present application with time when cyclically stretched at room temperature;

[0062] Figure 4 is a curve of the change of the resistance of the elastic conductive fiber (Example 1) of the present application with time when cyclically stretched at 80 DEG C;

[0063] Figure 5The following is a curve showing the change in resistance over time of the elastic conductive fiber (Example 1) with enhanced electrical properties at low temperatures according to the present invention when cyclically stretched at -15 to (-10)°C.

[0064] Figure 6 This is a curve showing the change in resistance over time of the elastic conductive fiber (Example 2) of the present invention when cyclically stretched at room temperature;

[0065] Figure 7 The following is a curve showing the change in resistance over time of the elastic conductive fiber with enhanced electrical properties at high temperatures (Example 2) of the present invention when cyclically stretched at 80°C.

[0066] Figure 8 The following is a curve showing the change in resistance over time of the elastic conductive fiber (Example 2) with enhanced electrical properties at low temperatures according to the present invention when cyclically stretched at -15 to (-10)°C.

[0067] Figure 9 This is a curve showing the change in resistance over time of the elastic conductive fiber (Example 3) of the present invention when cyclically stretched at room temperature;

[0068] Figure 10 The following is a curve showing the change in resistance over time of the elastic conductive fiber with enhanced electrical properties at high temperatures (Example 3) of the present invention when cyclically stretched at 80°C.

[0069] Figure 11 The following is a curve showing the change in resistance over time of the elastic conductive fiber (Example 3) with enhanced electrical properties at low temperatures according to the present invention when cyclically stretched at -15 to (-10)°C.

[0070] Figure 12 This is a curve showing the change in resistance over time of the elastic conductive fiber (Example 4) of the present invention when cyclically stretched at room temperature; Figure 13 The following is a curve showing the change in resistance over time of an elastic conductive fiber (Example 4) with enhanced electrical properties at high and low temperatures during heating from 25°C to 80°C / 110°C.

[0071] Figure 14 The following is a curve showing the change in resistance over time of the elastic conductive fiber with enhanced electrical properties at high and low temperatures (Example 4) of the present invention during cooling from room temperature to -20°C or below and then heating to 0°C;

[0072] Figure 15 The following is a curve showing the change in resistance over time of the elastic conductive fiber with enhanced electrical properties at high temperatures (Example 4) of the present invention when cyclically stretched at 80°C.

[0073] Figure 16The graph is a curve showing the change in resistance over time of the elastic conductive fiber (Example 4) with enhanced electrical properties at low temperatures according to the present invention when cyclically stretched at -15 to (-10)°C. DETAILED DESCRIPTION

[0074] Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiments are only used to illustrate the present invention and are not used in limiting the scope of the present invention.In addition, should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall equally within the scope limited by the appended claims of the application.

[0075] The test methods for the average diameter, mechanical properties, resistance change, and resistance change rate of the fibers in the examples are as follows:

[0076] (1) Test method for average fiber diameter and cross-sectional area: Fiber diameter was measured by using Image-pro Plus 5.0 image analysis software. Five fibers were selected from the electron microscope image and the average fiber diameter was calculated. Photoshop software was used to compare the scale of the fiber cross-sectional electron microscope image and calculate the cross-sectional area of ​​the fiber (mm). 2 ).

[0077] (2) Method for calculating the median particle size of liquid metal particles: Use Image-pro Plus 5.0 image analysis software and the scale of the electron microscope image to calculate the particle size of each particle in the electron microscope image, and use origin software to make a particle size distribution diagram to obtain the median particle size.

[0078] (3) Calculation method of the average size of silver flakes: Using Image-pro Plus 5.0 image analysis software and the ruler of the electron microscope image, the length of each silver flake in the electron microscope image was calculated to obtain the average size.

[0079] (4) Test method for fiber mechanical properties: First, 20 fibers were randomly selected from the composite fibers, fixed on a smooth plastic plate, and placed under standard atmospheric conditions for 24 h. Then, the tensile mechanical properties of each fiber were tested using a universal material testing machine. The test parameters were: the clamp distance l0 was 20 mm, the clamp tensile rate was 30 mm min-1, and the tensile strength was 100 nm. -1 , the pre-tension is 0.1 cN, and finally the stress-strain curve of each sample is obtained. The calculation formulas for the fiber's breaking strength Pf and breaking elongation ε are:

[0080]

[0081] Where: F i : breaking strength of the i-th fiber (unit: N);

[0082] Fiber linear density (unit: mm) 2 );

[0083] li: breaking elongation of the i-th fiber (unit: mm);

[0084] l0: Test length of the fiber (20 mm).

[0085] (5) Fiber resistance test method: A digital multimeter (Fluke 17B+, Fluke Corporation) was used to measure the fiber resistance. 20 mm was cut from different fibers for measurement, and the average value was calculated five times.

[0086] (6) Determination of resistance change rate during stretching at room temperature: Cut the fiber to a length of 3 cm, leaving 0.5 cm at each end, and stick them to a 1 cm × 0.5 cm single-sided conductive tape. Coat the joints between the fiber and the tape with conductive silver paste to ensure full contact between the fiber and the tape, and then wrap it with a layer of conductive tape of the same size. After the prepared sample is dried at room temperature, clamp the two ends to the workbench of the flexible electronic tester for cyclic stretching test. Use a source meter to record the resistance signal and calculate the resistance change rate. Set the parameters as follows: clamping distance 2 cm, stretching rate 30 mm min -1 , the tensile strains are set to 10%, 20%, 30%, 40%, 50%, and 60%, respectively.

[0087] Resistance change rate (%) = ΔR / R0×100% = (R-R0) / R0×100%

[0088] Where: R: real-time resistance of the fiber;

[0089] R0: initial resistance of the fiber;

[0090] ΔR: relative change in fiber resistance.

[0091] (7) Determination of resistance change rate during high temperature stretching: Cut the fiber to a length of 3 cm, leaving 0.5 cm at each end, and stick them to a 1 cm × 0.5 cm single-sided conductive tape. Coat the connection between the fiber and the tape with conductive silver paste to ensure full contact between the fiber and the tape, and then wrap it with a layer of conductive tape of the same size. After the prepared sample is dried at room temperature, one end is fixed on the heating table, and the other end is connected to the stretching platform with a long conductive tape for cyclic stretching test. The resistance signal is recorded using a source meter and the resistance change rate is calculated. The parameters are set as follows: clamping distance 2 cm, tensile strain is set to 60%, 80%, 100%, 120%, 140%, 160%, 180% respectively.

[0092] Resistance change rate (%) = ΔR / R0×100% = (R-R0) / R0×100%

[0093] Where: R: real-time resistance of the fiber;

[0094] R0: initial resistance of the fiber;

[0095] ΔR: relative change in fiber resistance.

[0096] (8) Determination of resistance change rate during low-temperature stretching: Cut the fiber to a length of 3 cm, leaving 0.5 cm at each end, and stick them to a 1 cm × 0.5 cm single-sided conductive tape. Coat the connection between the fiber and the tape with conductive silver paste to ensure full contact between the fiber and the tape, and then wrap it with a layer of conductive tape of the same size. After the prepared sample is dried at room temperature, one end is fixed to a low-temperature PTFE substrate (using a thermal imager to record the real-time temperature of the fiber), and the other end is connected to the stretching platform with a long conductive tape for cyclic stretching test. The resistance signal is recorded using a source meter and the resistance change rate is calculated. The parameters are set as follows: clamping distance 2 cm, tensile strain is set to 60%, 70%, and 80% respectively.

[0097] Resistance change rate (%) = ΔR / R0×100% = (R-R0) / R0×100%

[0098] Where: R: real-time resistance of the fiber;

[0099] R0: initial resistance of the fiber;

[0100] ΔR: relative change in fiber resistance.

[0101] (9) Resistance change during heating: Cut the fiber to a length of 3 cm, leaving 0.5 cm at each end, and secure it to a heating table with conductive tape. Heat the fiber sample and record the resistance signal using a Keithley 6510 source meter. The calculation formula is: Resistance change (%) = ΔR / R0 × 100% = (R-R0) / R0 × 100%

[0102] Where: R: real-time resistance of the fiber;

[0103] R0: initial resistance of the fiber;

[0104] ΔR: relative change in fiber resistance.

[0105] (10) Determination of resistance change during cooling process: Cut the fiber to a length of 3 cm, leaving 0.5 cm at each end, and fix it to a PTFE substrate frozen in liquid nitrogen using conductive tape. The fiber sample is cooled (the real-time temperature of the fiber is recorded using a thermal imager). During the cooling process of the fiber sample, the resistance signal is recorded using a Keithley 6510 source meter. The calculation formula is:

[0106] Resistance change rate (%) = ΔR / R0×100% = (R-R0) / R0×100%

[0107] Where: R: real-time resistance of the fiber;

[0108] R0: initial resistance of the fiber;

[0109] ΔR: relative change in fiber resistance.

[0110] The specific method for preparing the liquid metal particles in the embodiment is as follows: 2 grams of gallium-indium liquid metal alloy is placed in a large centrifuge tube, 10 ml of DMF solution is added, and high-speed shearing is performed at 12,000 rpm using a high-speed disperser for three minutes to obtain liquid metal particles with a median particle size of 40 μm; alternatively, high-speed shearing is performed for five minutes to obtain liquid metal particles with a median particle size of 20 μm. Repeat this process to obtain micro- / nano-gallium-indium liquid metal particles of the desired mass.

[0111] Example 1

[0112] In this embodiment, a composite elastic conductive fiber is provided. The preparation method of the conductive fiber is as follows: according to the polymer accounting for 20% of the total mass of the polymer and the solvent, 0.6 g of thermoplastic polyurethane (Shanghai Baijinrun Plastic Raw Materials Co., Ltd.) and 0.1 g of polyacrylic acid (Shanghai Aladdin Biochemical Technology Co., Ltd.) are weighed, added to a dimethylformamide solvent (Shanghai Aladdin Biochemical Technology Co., Ltd.), and magnetically stirred in an 80°C water bath for 2 hours to obtain a colorless and transparent spinning solution; 1.8 g of silver micro-sheets (average size of 5 μm) are added to the above spinning solution, and magnetically stirred for 12 hours in a room temperature water bath to obtain a uniform spinning solution; 3.6 g of micro / nano gallium indium liquid metal particles (median particle size of 40 μm) are then added to the above spinning solution, and magnetically stirred at room temperature for 24 hours and at high speed for 20 minutes to obtain a uniform spinning solution; the spinning solution is allowed to stand for 1 hour for degassing, and the spinning solution is advanced at a speed of 50 ml h -1 Wet spinning was performed under the conditions of a needle diameter of 16G. After solidification and drying, the average diameter was 925μm and the initial resistance was 9Ω·cm. -1 Elastic conductive fibers (such as Figure 1 As shown), the maximum stress and tensile strain of the fiber can reach 2.3MPa and 470% (as shown). Figure 2 At room temperature, when the tensile strain is 10%, 20%, 30%, 40%, and 50%, the fiber has a relatively stable resistance response (as shown in Figure 3 When the temperature of the elastic conductive fiber is raised from 25°C to 80°C or 100°C, the resistance change does not show a downward trend; when the temperature of the elastic conductive fiber is lowered from 25°C to -20°C, the resistance change does not show a downward trend.

[0113] The elastic conductive fiber was stretched 30 times at 50% strain at 80°C to obtain an elastic conductive fiber with self-enhanced electrical properties at high temperature. At 80°C, when the tensile strain was 60%, 80%, 100%, 120%, 140%, and 160%, the elastic conductive fiber had stable resistance responsiveness (such as Figure 4 shown).

[0114] The elastic conductive fiber was stretched 10 times at a strain of 20% at -15 to (-10) ° C to obtain an elastic conductive fiber with self-enhanced electrical properties at low temperatures. At -15 to (-10) ° C, when the tensile strain was 60% and 70%, the elastic conductive fiber had a stable resistance response (such as Figure 5 shown).

[0115] Example 2

[0116] In this embodiment, a composite elastic conductive fiber is provided. The preparation method of the conductive fiber is as follows: according to the polymer accounting for 20% of the total mass of the polymer and the solvent, 0.6 g of thermoplastic polyurethane (Shanghai Baijinrun Plastic Raw Materials Co., Ltd.) is weighed and added to a dimethylformamide solvent (Shanghai Aladdin Biochemical Technology Co., Ltd.), and magnetically stirred in an 80°C water bath for 2 hours to obtain a colorless and transparent spinning solution; 1.8 g of silver micro-sheets (average size of 5 μm) are added to the above spinning solution, and magnetically stirred for 12 hours in a room temperature water bath to obtain a uniform spinning solution; 3.6 g of micro / nano gallium indium liquid metal particles (median particle size of 40 μm) are then added to the above spinning solution, and magnetically stirred at room temperature for 24 hours and at high speed for 20 minutes to obtain a uniform spinning solution; the spinning solution is allowed to stand for 1 hour for degassing, and the spinning solution is advanced at a speed of 50 ml h -1 Wet spinning was performed under the conditions of a needle diameter of 16G. After solidification and drying, the average diameter was 915μm and the initial resistance was 12Ω·cm. -1 Elastic conductive fiber. Under room temperature, when the tensile strain is 10%, 20%, 30%, 40%, and 50%, the as-spun fiber has a relatively stable resistance response (such as Figure 6 When the temperature of the elastic conductive fiber is raised from 25°C to 80°C or 100°C, the resistance change does not show a downward trend; when the temperature of the elastic conductive fiber is lowered from 25°C to -20°C, the resistance change does not show a downward trend.

[0117] The elastic conductive fiber was stretched 30 times at 50% strain in an 80°C environment to obtain an elastic conductive fiber with self-enhanced electrical properties at high temperatures. At 80°C, when the tensile strain was 60%, 80%, 100%, 120%, and 140%, the elastic conductive fiber had a relatively stable resistance response under repeated deformation (such as Figure 7 shown).

[0118] By cyclically stretching the elastic conductive fiber 10 times at a strain of 20% in an environment of -15 to (-10) ° C, an elastic conductive fiber with self-enhanced electrical properties at low temperatures can be obtained. At -15 to (-10) ° C, when the tensile strain is 60% and 70%, the elastic conductive fiber has a relatively stable resistance response (such as Figure 8 shown).

[0119] Example 3

[0120] In this embodiment, a composite elastic conductive fiber is provided. The preparation method of the conductive fiber is as follows: according to the polymer accounting for 20% of the total mass of the polymer and the solvent, 0.6 g of thermoplastic polyurethane (Shanghai Baijinrun Plastic Raw Materials Co., Ltd.) and 0.1 g of polyacrylic acid (Shanghai Aladdin Biochemical Technology Co., Ltd.) are weighed and added to a dimethylformamide solvent (Shanghai Aladdin Biochemical Technology Co., Ltd.), and magnetically stirred in an 80°C water bath for 2 hours to obtain a colorless and transparent spinning solution; 1.8 g of silver micro-sheets (average size of 5 μm) are added to the above spinning solution, and magnetically stirred in a room temperature water bath for 12 hours to obtain a uniform spinning solution; the spinning solution is allowed to stand for 1 hour to deaerate, and the spinning solution is fed at a speed of 50 ml h -1 Wet spinning was performed under the conditions of a needle diameter of 16G. After solidification and drying, the average diameter was 950μm and the initial resistance was 14Ω·cm. -1 At room temperature, when the tensile strain is 10%, 20%, and 30%, the newly formed fiber has an unstable resistance response (such as Figure 9 When the temperature of the elastic conductive fiber is raised from 25°C to 80°C or 100°C, the resistance change does not show a downward trend; when the temperature of the elastic conductive fiber is lowered from 25°C to -20°C, the resistance change does not show a downward trend.

[0121] The elastic conductive fiber was stretched 30 times at 50% strain in an 80°C environment to obtain an elastic conductive fiber with self-enhanced electrical properties at high temperatures. At 80°C, when the tensile strain was 60%, 80%, and 100%, the elastic conductive fiber had a relatively stable resistance response under repeated deformation (such as Figure 10 shown).

[0122] By cyclically stretching the elastic conductive fiber 10 times at a strain of 20% in an environment of -15 to (-10) ° C, an elastic conductive fiber with self-enhanced electrical properties at low temperatures can be obtained. At -15 to (-10) ° C, when the tensile strain is 60%, the elastic conductive fiber has a relatively stable resistance response (such as Figure 11 shown).

[0123] Example 4

[0124] In this embodiment, a composite elastic conductive fiber is provided. The preparation method of the conductive fiber is as follows: according to the polymer accounting for 22% of the total mass of the polymer and the solvent, 0.7 g of styrene ethyl butylene styrene (SEBS) (Asahi Chemical Industry Co., Ltd., Japan) and 0.15 g of polymethyl methacrylate (Shanghai Aladdin Biochemical Technology Co., Ltd.) are weighed and added to an organic solvent of toluene (Shanghai Aladdin Biochemical Technology Co., Ltd.), and magnetically stirred for 2 hours at a water bath temperature of 110°C to obtain a colorless and transparent spinning solution; 2.5 g of silver micro-sheets (average size of 10 μm) are added to the above spinning solution, and magnetically stirred for 12 hours at room temperature in a water bath to obtain a uniform spinning solution; 4 g of micro / nano-gallium indium liquid metal particles (median particle size of 20 μm) are added to the above spinning solution, and magnetically stirred for 24 hours at room temperature and at high speed for 20 minutes to obtain a uniform spinning solution; the spinning solution is allowed to stand for 1 hour for degassing, and the spinning solution is advanced at a speed of 50 ml h -1 Wet spinning was performed under the conditions of a needle diameter of 16G. After solidification and drying, the average diameter was 930μm and the initial resistance was 11Ω·cm. -1 At room temperature, when the tensile strain is 10%, 20%, 30%, and 40%, the primary fiber has a relatively stable resistance response (such as Figure 12 When the temperature of the elastic conductive fiber is raised from 25°C to 80°C or 100°C, the resistance change does not show a downward trend; when the temperature of the elastic conductive fiber is lowered from 25°C to -20°C, the resistance change does not show a downward trend.

[0125] The fiber was heated on a 200°C heating table for 5 minutes and then returned to room temperature to obtain an elastic conductive fiber with self-enhanced electrical properties in high and low temperature environments. When the elastic conductive fiber was heated from 25°C to 80°C or 100°C, its resistance decreased, and the decrease at 100°C was greater than that at 80°C, indicating that the conductive path of the fiber can be self-enhanced in a thermal environment, improving conductivity (such as Figure 13 When the elastic conductive fiber is cooled from 25℃ to -20℃, its resistance decreases and its conductivity increases (as shown in Figure 2). Figure 14 shown).

[0126] The elastic conductive fiber was stretched 20 times at 40% strain in an 80°C environment to obtain an elastic conductive fiber with self-enhanced electrical properties at high temperatures. At 80°C, when the tensile strain was 60%, 80%, 100%, 120%, 140%, and 160%, the elastic conductive fiber had a relatively stable resistance response under repeated deformation (such as Figure 15 shown).

[0127] By cyclically stretching the elastic conductive fiber 20 times at a strain of 15% in an environment of -15 to (-10) ° C, an elastic conductive fiber with self-enhanced electrical properties at low temperatures can be obtained. At -15 to (-10) ° C, when the tensile strain is 60% and 70%, the elastic conductive fiber has a relatively stable resistance response (such as Figure 16 shown).

[0128] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Persons skilled in the art will readily appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. An elastic conductive fiber with autonomously enhanced electrical properties at high and low temperatures, characterized in that: The elastic conductive fiber with autonomously enhanced electrical properties at high and low temperatures is obtained by subjecting the elastic conductive fiber to static high-temperature, dynamic cyclic stretching at high temperature, or dynamic cyclic stretching at low temperature; wherein the static high-temperature treatment temperature is 20-250° C. and the time is 1-100 minutes; At high temperature, the dynamic cyclic stretching temperature is 50~150℃, the time is 1-100min, the dynamic cyclic stretching strain is 1%~300%, and the number of cycles is 1~50; at low temperature, the dynamic cyclic stretching temperature is -20~0℃, the time is 1-100min, the dynamic cyclic stretching strain is 1%~300%, and the number of cycles is 1~50; The elastic conductive fiber comprises: an elastomer and a conductive filler; the conductive filler is a solid conductive filler and a conductive liquid, and the mass ratio of the conductive liquid to the solid conductive filler is 1:100 to 10:1; the median particle size of the conductive liquid is 500 nm to 100 µm; the conductive liquid comprises a gallium alloy; and the gallium alloy comprises at least one of a gallium-indium alloy and a gallium-indium-tin alloy.

2. The elastic conductive fiber with autonomously enhanced electrical properties at high and low temperatures according to claim 1, characterized in that: The average size of the solid conductive filler is 1 to 15 μm; the mass ratio of the conductive filler to the elastomer is 1:100 to 30:1; the solid conductive filler includes one or more of a conductive polymer, MXene, a metal micro-nano material, and a carbon-based micro-nano material; wherein the metal micro-nano material includes metal micro-nano particles, metal micro-nano sheets, metal nanowires, and metal nanorods.

3. The elastic conductive fiber with autonomously enhanced electrical properties at high and low temperatures according to claim 2, characterized in that: The solid conductive filler includes one or more of MXene, silver micro-nanosheets, copper micro-nanosheets, silver nanowires, copper nanowires, silver nanoparticles, silver microspheres, copper microspheres, graphite, carbon black, carbon nanotubes, graphene, graphene oxide and their modifications.

4. The elastic conductive fiber with autonomously enhanced electrical properties at high and low temperatures according to claim 1, characterized in that: The elastomer includes one or more of polyurethane, polydimethylsiloxane, styrene block copolymer, ethylene-vinyl acetate copolymer, and isoprene copolymer; The elastic conductive fiber also contains a reinforcing agent; The mass ratio of the reinforcing agent to the elastomer is 1:50 to 5:1; The enhancer is an enhancer containing active functional groups; The active functional group-containing enhancer includes one or more of polyacrylic acid, polymethyl methacrylate, polyethyleneimine, and polycaprolactam; The conductive fiber morphology includes at least one of single fiber, yarn, fiber mat, fiber film, and fabric; the conductive fiber diameter is 200 μm~1 mm.

5. The elastic conductive fiber with autonomously enhanced electrical properties at high and low temperatures according to claim 1 or 4, characterized in that: The method for preparing the elastic conductive fiber comprises: The elastomer and solvent are mixed and stirred, a solid conductive filler is added and stirred, a conductive liquid is added and stirred to obtain a spinning solution, the spinning solution is degassed and then spun, solidified and formed, and dried to obtain an elastic conductive fiber; Alternatively, the elastomer, reinforcing agent, and solvent are mixed and stirred, a solid conductive filler is added and stirred, a conductive liquid is added and stirred to obtain a spinning solution, the solution is degassed and then spun, solidified and formed, and dried to obtain an elastic conductive fiber.

6. The elastic conductive fiber with autonomously enhanced electrical properties at high and low temperatures according to claim 5, characterized in that: The solvent includes one or more of water, ethanol, acetone, isopropanol, toluene, tetrahydrofuran, pyridine, N,N-dimethylformamide, and thionyl chloride; The mass concentration of the elastomer after the elastomer and the solvent are mixed is 5 wt% to 70 wt%; After the elastomer, reinforcing agent and solvent are mixed, the mass concentration of the elastomer is 5 wt% to 70 wt%.

7. The elastic conductive fiber with autonomously enhanced electrical properties at high and low temperatures according to claim 5, characterized in that: The spinning is wet spinning; the elastomer and the solvent are mixed or the elastomer, the reinforcing agent and the solvent are mixed and stirred at a temperature of 20 to 150° C. for 1 to 3 hours, a solid conductive filler is added and stirred for 5 to 30 hours, and a conductive liquid is added and stirred for 5 to 30 hours to obtain a spinning solution; The conductive liquid is a conductive liquid that has been dispersed, wherein the dispersion treatment method includes one or more of mechanical stirring, high-speed shearing, and ultrasonic treatment.

8. Use of the elastic conductive fiber with autonomously enhanced electrical properties at high and low temperatures as claimed in claim 1 in the fields of optoelectronics, information, energy, medical treatment or national defense.

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