Liquid metal-carbon nanotube-polyurethane-polypyrrole composite functional fiber material as well as preparation method and application thereof

Abstract

The invention provides a liquid metal-carbon nanotube-polyurethane-polypyrrole composite functional fiber material as well as a preparation method and application thereof, and belongs to the technical field of conductive fibers. Through core-shell structure design and a wet spinning technology, liquid metal LM and CNTs are used as core materials, thermoplastic polyurethane (TPU) is used as a shell material, and the composite functional fiber material with a novel core-shell structure is prepared through the wet spinning technology, so that stable packaging and functional directional regulation and control of the LM in the TPU are realized. In addition, the structure not only keeps the conductivity of the core material, but also endows the shell part with conductivity through in-situ polymerization of pyrrole on the surface of the fiber, so that the overall high conductivity of the fiber is realized. Besides, the composite functional fiber material has good sound absorption performance and low dielectric constant, sound absorption, sensing and self-powered mechanisms can be combined, and the integrated requirements of noise control and self-powered sensing monitoring in different occasions are met.

Description

Technical Field

[0001] The present invention relates to the technical field of conductive fibers, and particularly to a liquid metal-carbon nanotube-polyurethane-polypyrrole composite functional fiber material, a preparation method thereof, and an application thereof. Background Art

[0002] Liquid Metal (LM) is a metal or metal alloy that is liquid at room temperature and has excellent fluidity, deformability, and electrical conductivity. Therefore, it shows broad application prospects in the fields of flexible electronics, intelligent sensing, etc. However, the high fluidity of LM also brings problems such as easy leakage and oxidation, which limit its practical application in polymer composites. To improve the problem of easy shedding of LM during practical use, various solutions have been proposed in the prior art. For example, Patent CN 118241337A uses aramid as a fiber shell to improve its stability by coating LM. However, due to the high viscosity of the aramid solution, it may cause uneven dispersion of LM, which in turn leads to particle agglomeration and affects the electrical conductivity of the fiber.

[0003] In addition, carbon nanotubes (CNTs), as a high-performance nanomaterial, have excellent electrical conductivity and mechanical properties and are often used to enhance the properties of composite materials. However, the dispersion problem of CNTs in the polymer matrix is still a technical difficulty, and the agglomeration phenomenon will significantly reduce the performance of the composite material. Therefore, how to achieve uniform dispersion of LM and CNTs in the polymer matrix and at the same time maintain the electrical conductivity and functionality of the material is an important challenge in current research. Wet spinning is an important method for large-scale preparation of fiber materials, which can make nanomaterials such as CNTs and liquid metal nanoparticles (LMNPs) into continuous fibers, improving their processability and application range. TPU, as a commonly used wet spinning solution, has good wear resistance, flexibility, and biocompatibility and is widely used in the fields of textiles, medicine, and electronics. However, there is currently little research on composite fiber materials that integrate electrical conductivity, flexibility, and multifunctionality. Developing a new type of fiber material with multifunctional integration such as self-power supply, sensing, and efficient sound absorption has important practical significance. Summary of the Invention

[0004] The purpose of the present invention is to provide a liquid metal-carbon nanotube-polyurethane-polypyrrole composite functional fiber material, a preparation method thereof, and an application thereof, which can combine sound absorption, sensing, and self-power supply mechanisms to meet the integrated requirements of noise control and self-power supply sensing monitoring in different scenarios.

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

[0006] The present invention provides a method for preparing a liquid metal-carbon nanotube-polyurethane-polypyrrole composite functional fiber material, comprising the following steps:

[0007] Mix liquid metal, carbon nanotubes and an organic solvent, and disperse them to obtain a liquid metal-carbon nanotube dispersion;

[0008] Heat and mix the liquid metal-carbon nanotube dispersion with polyurethane to obtain a spinning solution;

[0009] Perform wet spinning of the spinning solution in a first coagulation bath and a second coagulation bath in sequence, and apply a direct current electric field in the second coagulation bath to obtain an LM / CNTs / TPU composite conductive fiber;

[0010] Mix pyrrole, p-toluenesulfonic acid and water to obtain a monomer solution;

[0011] Immerse the LM / CNTs / TPU composite conductive fiber in the monomer solution, add an oxidant, and carry out a polymerization reaction to obtain a liquid metal-carbon nanotube-polyurethane-polypyrrole composite functional fiber material.

[0012] Preferably, the liquid metal includes one or more of gallium indium alloy, gallium indium tin alloy and gallium tin alloy.

[0013] Preferably, the mass ratio of the liquid metal to the carbon nanotubes is 4-8:1-2; the mass ratio of the polyurethane to the liquid metal is 50-100:4-8.

[0014] Preferably, the dispersion is carried out under ultrasonic conditions, the power of the ultrasonic wave is 270-540 W, and the time is 20-50 min; the temperature of the heat mixing is 50-60 °C, and the time is 4-12 h.

[0015] Preferably, the first coagulation bath is water, and the temperature of the first coagulation bath is 5-15 °C; the second coagulation bath is an ethanol-water mixture, and the temperature of the second coagulation bath is 30-40 °C.

[0016] Preferably, the electric field strength of the direct current electric field is 1-5 V / cm -1 ; the advancing speed of the wet spinning is 5-8 mL / min -1 .

[0017] Preferably, the dosage ratio of pyrrole, p-toluenesulfonic acid and water is 0.3-0.5 mL:0.4-0.6 g:20-40 mL; the oxidant includes iron salt, ammonium persulfate or H2O2; the dosage ratio of the oxidant to pyrrole is 0.67-1.07 g:0.3-0.5 mL.

[0018] Preferably, the temperature of the polymerization reaction is 0-8 °C, and the polymerization time is 5-8 h.

[0019] The present invention provides a liquid metal-carbon nanotube-polyurethane-polypyrrole composite functional fiber material prepared by the preparation method described in the above technical solution.

[0020] The present invention provides the application of the liquid metal-carbon nanotube-polyurethane-polypyrrole composite functional fiber material described in the above technical solution in the fields of resistive strain sensors, triboelectric power generation or sound absorption.

[0021] The present invention provides a preparation method of a liquid metal-carbon nanotube-polyurethane-polypyrrole (LM / CNTs / TPU / PPy) composite functional fiber material. Through the core-shell structure design and wet spinning technology, the present invention uses liquid metal LM and carbon nanotubes CNTs as the core materials and thermoplastic polyurethane (TPU) as the shell material to prepare a novel core-shell structure composite functional fiber material by wet spinning technology, realizing the stable encapsulation and functional directional regulation of LM in TPU. In addition, this structure not only maintains the conductivity of the core material, but also endows the shell with conductivity by in-situ polymerization of pyrrole on the fiber surface, thereby realizing the high conductivity of the whole fiber.

[0022] In the LM / CNTs / TPU / PPy composite functional fiber material of the present invention, the introduction of CNTs can connect the dispersed liquid metal nanoparticles (LMNPs) to form a continuous conductive path. The high fluidity of LM endows it with excellent deformability, enabling it to withstand a large range of deformations and adapt to complex weaving processes without breaking or being damaged. After the polymerization of Py, the LM / CNTs / PU / PPy fiber has good conductivity, can light up an LED bulb in a stretched state, and at the same time its mechanical properties are also improved, and it can be interwoven with pure cotton yarn to form a plain fabric. In triboelectric power generation applications, the elasticity of TPU and the flow characteristics of LM can realize the collection of mechanical signals of multiple frequencies. PPy improves the surface roughness of the material, increases the frictional contact area, and the excellent conductivity can improve the capture and transmission ability of surface charges. The CNTs with a high aspect ratio have a large specific surface area, making the interaction between them more sufficient when stimulated by the outside world, thus generating a highly sensitive sensing signal response, and the stable resistance change can ensure the reliability of its long-term operation. During the solidification process of TPU, a microporous structure is formed by the rapid exchange of solvent and non-solvent. At the same time, the heat converted by sound energy can be quickly diffused through the high thermal conductivity network of LM / CNTs, and the two work together to improve the sound absorption effect.

[0023] The composite functional fiber material prepared by the present invention belongs to a new type of fiber material with excellent electrical conductivity, flexibility and multi-functional integration, which can meet the requirements of high-performance materials in the fields of flexible electronics, intelligent sensing, etc. The composite functional fiber material described in the present invention integrates self-powered (triboelectric nanogenerator), sensing, conductive and sound absorption applications in series, realizing multi-functional integration, improving the portability and practicality of the material, expanding the application scope of wearable electronic devices, and can be used in resistive strain sensors, triboelectric power generation and sound absorption fields.

[0024] In addition, the core-shell structure design enables TPU to wrap LM, making LM not easily leak, effectively solving the problems of easy leakage and oxidation of LM, and at the same time improving the dispersion of CNTs in the polymer matrix. Therefore, the present invention solves the problems that the application of LM is restricted by problems such as its easy leakage and oxidation, and the dispersion problem of CNTs in polymers.

[0025] The solution of the present invention can further precisely control the microscopic morphology of LM and its structural arrangement inside the fiber by combining the double coagulation bath and the applied electric field technology. At the same time, the prepared fiber can be recycled again through organic solvents, which is green and environmentally friendly. Brief Description of the Drawings

[0026] Figure 1 It is the preparation flow chart of the LM / CNTs / TPU / PPy composite functional fiber material in the present invention;

[0027] Figure 2 It is the SEM images of TPU (a - b) in Comparative Example 1 and LM / CNTs / TPU (c - d) in Comparative Example 2 at different magnifications;

[0028] Figure 3 It is the SEM image of the LM / CNTs / TPU / PPy - 2 composite functional fiber material in Example 2. Both (a) and (c) are SEM images at 800μm, (b) is a partial enlarged view of (a), and (d) is a partial enlarged view of (c);

[0029] Figure 4 It is the EDS spectrum of the LM / CNTs / TPU / PPy - 2 composite functional fiber material in Example 2. (a) is the total EDS spectrum of LM / CNTs / TPU / PPy - 2, and (b - f) represent the element distribution maps of Ga, In, Sn, N and C in sequence;

[0030] Figure 5 It is the XRD patterns of the TPU fiber in Comparative Example 1, the LM / CNTs / TPU fiber in Comparative Example 2 and the LM / CNTs / TPU / PPy - 2 fiber in Example 2;

[0031] Figure 6Mechanical property diagrams of the TPU fibers in Comparative Example 1, the LM / CNTs / TPU fibers in Comparative Example 2, the LM / CNTs / TPU / PPy-5 fibers in Comparative Example 3, and the LM / CNTs / TPU / PPy-2 fibers in Example 2;

[0032] Figure 7 Electrical property diagram of the LM / CNTs / TPU / PPy-2 composite functional fiber material in Example 2;

[0033] Figure 8 Conductive property diagrams of the TPU fibers (a) in Comparative Example 1 and the LM / CNTs / TPU fibers (b) in Comparative Example 2;

[0034] Figure 9 Weaving physical diagram of the LM / CNTs / TPU / PPy-2 composite functional fiber material in Example 2;

[0035] Figure 10 Sensing property diagrams of the LM / CNTs / TPU / PPy-2 composite functional fiber material in Example 2 at different human body parts, where (a) finger, (b) arm, (c) brow, (d) back of the neck, (e) throat, (f) ankle;

[0036] Figure 11 Sound absorption property diagram of the LM / CNTs / TPU / PPy-2 composite functional fiber material in Example 2;

[0037] Figure 12 Triboelectric generation principle diagram of the LM / CNTs / TPU / PPy-2 composite functional fiber material in Example 2;

[0038] Figure 13 Triboelectric generation property diagrams of the LM / CNTs / TPU / PPy-2 composite functional fiber material in Example 2; where (a - c) represent the open-circuit voltage (VOC) under the conditions of 1 Hz, 2 Hz, and 3 Hz in sequence, (d - f) represent the short-circuit current (ISC) under the conditions of 1 Hz, 2 Hz, and 3 Hz in sequence, and (g - i) represent the short-circuit charge transfer (QSC) under the conditions of 1 Hz, 2 Hz, and 3 Hz in sequence. Detailed implementation manners

[0039] In the present invention, unless otherwise specified, the raw materials or reagents required for preparation are all commercially available products well-known to those skilled in the art.

[0040] As Figure 1 shown, the present invention provides a preparation method of a liquid metal-carbon nanotube-polyurethane-polypyrrole composite functional fiber material, comprising the following steps:

[0041] Mix liquid metal, carbon nanotubes and organic solvent, and disperse them to obtain a liquid metal-carbon nanotube dispersion;

[0042] Heat and mix the liquid metal-carbon nanotube dispersion with polyurethane to obtain a spinning solution;

[0043] Carry out wet spinning of the spinning solution in a first coagulation bath and a second coagulation bath in sequence, and apply a direct current electric field in the second coagulation bath to obtain an LM / CNTs / TPU composite conductive fiber;

[0044] Mix pyrrole, p-toluenesulfonic acid and water to obtain a monomer solution;

[0045] Immerse the LM / CNTs / TPU composite conductive fiber in the monomer solution, add an oxidant, and carry out a polymerization reaction to obtain a liquid metal-carbon nanotube-polyurethane-polypyrrole composite functional fiber material.

[0046] In the present invention, liquid metal, carbon nanotubes and organic solvent are mixed and dispersed to obtain a liquid metal-carbon nanotube dispersion.

[0047] In the present invention, the liquid metal preferably includes one or more of gallium indium alloy, gallium indium tin alloy and gallium tin alloy, and more preferably gallium indium tin alloy. The present invention has no special limitation on the source of the liquid metal, and commercially available liquid metals well-known in the art can be used.

[0048] In the present invention, the mass ratio of the liquid metal to the carbon nanotubes is preferably 4-8:1-2, more preferably 4-6:1; the present invention has no special limitation on the specifications of the carbon nanotubes, and commercially available carbon nanotubes well-known in the art can be used.

[0049] In the present invention, the organic solvent is preferably DMF; the present invention has no special limitation on the dosage of the organic solvent, and it is only necessary to ensure uniform dispersion of the materials.

[0050] In the present invention, the dispersion is preferably carried out under ultrasonic conditions. The power of the ultrasonic wave is preferably 270-540W, more preferably 330-360W, further preferably 340-350W, and the time is preferably 20-50min, more preferably 30-40min; the ultrasonic wave is preferably carried out under an ice-water bath condition.

[0051] After obtaining the liquid metal-carbon nanotube dispersion, the present invention heats and mixes the liquid metal-carbon nanotube dispersion with polyurethane to obtain a spinning solution.

[0052] In the present invention, the mass ratio of the polyurethane to the liquid metal is preferably 50 to 100:4 to 8, more preferably 50 to 70:4 to 6; the polyurethane is preferably thermoplastic polyurethane; the present invention places no special limitation on the source of the polyurethane, and commercially available products well-known in the art can be used.

[0053] The present invention preferably adds the polyurethane to the liquid metal-carbon nanotube dispersion and performs heat mixing under stirring conditions.

[0054] In the present invention, the temperature of the heat mixing is preferably 50 to 60 °C, more preferably 55 °C; the time is preferably 4 to 12 h, more preferably 8 to 10 h; the heat mixing is preferably carried out under oil bath heating conditions.

[0055] After obtaining the spinning solution, the present invention performs wet spinning of the spinning solution in a first coagulation bath and a second coagulation bath in sequence, and applies a direct current electric field in the second coagulation bath to obtain the LM / CNTs / TPU composite conductive fiber.

[0056] The present invention preferably fills the spinning solution into a syringe and performs wet spinning in a layered coagulation bath.

[0057] The present invention preferably uses a self-built wet spinning device for spinning. The present invention places no special limitation on the wet spinning device, and any push pump spinning device well-known in the art can be used.

[0058] After the spinning solution is led out from the first coagulation bath in the present invention, it is directly introduced into the second coagulation bath for wet spinning. In the present invention, the first coagulation bath is preferably water, and the temperature of the first coagulation bath is preferably 5 to 15 °C, more preferably 10 °C; the second coagulation bath is preferably an ethanol-water mixture, and the volume ratio of ethanol to water is preferably 3:7 to 5:5, more preferably 4:6; the temperature of the second coagulation bath is preferably 30 to 40 °C, more preferably 35 °C. The present invention rapidly cures the TPU shell through the first coagulation bath and induces the directional migration of the liquid metal inner phase through the second coagulation bath to form a core-shell structure.

[0059] In the present invention, the electric field strength of the direct current electric field is preferably 1 to 5 V / cm -1 , more preferably 2 to 4 V, and further preferably 3 V / cm -1 ; the advancing speed of the wet spinning is preferably 5 to 8 mL / min, more preferably 6 to 8 mL / min, and the inner diameter of the needle is preferably 0.2 mm. The present invention controls the internal structure arrangement of the fiber by applying a direct current electric field in the coagulation bath and utilizing the conductivity of the liquid metal.

[0060] After completing the wet spinning, the present invention preferably dries the obtained composite fiber at room temperature to obtain the LM / CNTs / TPU composite conductive fiber.

[0061] In the present invention, pyrrole, p-toluenesulfonic acid and water are mixed to obtain a monomer solution; the LM / CNTs / TPU composite conductive fiber is immersed in the monomer solution, and an oxidant is added to carry out a polymerization reaction to obtain an LM / CNTs / TPU / PPy composite functional fiber material.

[0062] In the present invention, the dosage ratio of pyrrole, p-toluenesulfonic acid and water is preferably 0.3 - 0.5 mL: 0.4 - 0.6 g: 20 - 40 mL, more preferably 0.35 - 0.45 mL: 0.45 - 0.55 g: 25 - 35 mL, and further preferably 0.4 mL: 0.5 g: 30 mL. In the present invention, pyrrole and p-toluenesulfonic acid are preferably added to water and mixed, and stirred at a low temperature of 5 - 20 °C for 30 min to obtain a monomer solution.

[0063] In the present invention, the LM / CNTs / TPU composite conductive fiber is preferably cut into a length of 10 - 50 cm and then completely immersed in the monomer solution; the immersion time is preferably 10 - 15 min, more preferably 10 min. The present invention has no special limitation on the dosage ratio of the LM / CNTs / TPU composite conductive fiber to the monomer solution, as long as the composite conductive fiber is completely immersed in the monomer solution; the immersion amount is limited by the immersion time.

[0064] In the present invention, the oxidant preferably includes iron salt, ammonium persulfate or H2O2, and the iron salt is preferably FeCl3·6H2O. In the present invention, the oxidant is preferably dissolved in water to form an oxidant aqueous solution for use, and the dosage ratio of the oxidant to water in the oxidant aqueous solution is preferably 0.67 - 1.07 g: 10 - 30 mL, more preferably 0.7 - 1 g: 15 - 30 mL, and further preferably 0.87 g: 30 mL.

[0065] In the present invention, the dosage ratio of the oxidant to pyrrole is preferably 0.67 - 1.07 g: 0.3 - 0.5 mL, more preferably 0.7 - 1 g: 0.35 - 0.45 mL, and further preferably 0.87: 0.4 mL.

[0066] In the present invention, the oxidant aqueous solution is preferably added dropwise to the impregnated mixture to carry out a polymerization reaction.

[0067] In the present invention, the temperature of the polymerization reaction is preferably 0 - 8 °C, more preferably 0 - 5 °C, and the polymerization time is preferably 5 - 8 h, more preferably 5 - 6 h. During the polymerization reaction, FeCl3·6H2O serves as an oxidant to provide Fe 3+ , oxidizing pyrrole monomers to generate radical cations (Py ·+ ). Two Py ·+Coupling through the α-position (2 or 5-position) carbon atoms to form a dimer and release 2 H + , and the dimer continues to be oxidized by Fe 3+ , react with more monomers or oligomers, gradually extend the conjugated chain, and form polypyrrole (PPy). After completing the polymerization reaction, the present invention preferably takes out the obtained fiber, washes it clean with deionized water, and dries it at 60-70 °C under vacuum for 5-8 h.

[0068] The present invention provides a liquid metal-carbon nanotube-polyurethane-polypyrrole composite functional fiber material prepared by the preparation method described in the above technical solution.

[0069] The present invention provides the application of the liquid metal-carbon nanotube-polyurethane-polypyrrole composite functional fiber material described in the above technical solution in the fields of resistive strain sensors, triboelectric power generation or sound absorption. The present invention has no special limitation on the method of the application, and the liquid metal-carbon nanotube-polyurethane-polypyrrole composite functional fiber material can be used in the above fields according to the methods well known in the art.

[0070] The specific embodiments of the present invention will be described in detail below, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the protection scope of the present invention. The experimental methods described in the embodiments of the present invention are all conventional methods unless otherwise specified.

[0071] The following experimental methods and detection methods are all conventional methods unless otherwise specified; the following reagents and raw materials are all commercially available unless otherwise specified.

[0072] In the following examples and comparative examples, the polyurethane (TPU) used is from BASF Corporation, Germany (1185A); the carbon nanotubes are from Nanjing Pioneer Nanotechnology Co., Ltd. (purity 95%);

[0073] The gallium-indium-tin alloy LM, with the mass fractions of each element being 68% Ga, 22% In, and 10% Sn, is from Dongguan Dingguan Metal Technology Co., Ltd.

[0074] Example 1

[0075] 1) Add 0.4 g of gallium-indium-tin alloy LM and 0.1 g of CNTs to 20 mL of DMF, and use an ultrasonic cell disruptor to treat it at 330 W for 30 min in an ice-water bath to obtain an LM-CNT dispersion;

[0076] 2) Add 5 g of TPU to the LM-CNT dispersion obtained in step 1), heat and stir it in an oil bath at 55 °C for 4 h to obtain a spinning solution;

[0077] 3) Load the spinning solution obtained in step 2) into a syringe with a pushing speed of 8 mL / min and a needle inner diameter of 0.2 mm. After wet spinning in the first coagulation bath, draw it out and directly introduce it into the second coagulation bath for continuous spinning. The first coagulation bath is water at a temperature of 10 °C, and the second coagulation bath is an ethanol / water mixture at 35 °C with a volume ratio of ethanol to water of 3:7. Apply a DC electric field of 3 V / cm in the second coagulation bath -1 , and dry the spun fibers at room temperature to obtain LM / CNTs / TPU composite fibers;

[0078] 4) Add 0.4 mL of pyrrole and 0.5 g of p-toluenesulfonic acid to 30 mL of deionized water and mix. Stir at a low temperature of 5 °C for 30 min to obtain a monomer solution;

[0079] 5) After cutting the composite fibers obtained in step 3) to a length of 50 cm (fiber mass is 0.4 g), completely immerse them in the monomer solution for 10 min;

[0080] 6) Add 0.87 g of FeCl3·6H2O to 30 mL of deionized water and mix. Dropwise add the obtained iron salt solution into the mixture after soaking in step 5), polymerize at 0 °C for 5 h, take out the fibers, wash them clean with deionized water, and dry them in a vacuum at 60 °C for 5 h to obtain LM / CNTs / TPU / PPy-1 composite functional fiber material.

[0081] Example 2

[0082] 1) Add 0.6 g of gallium indium tin alloy LM and 0.1 g of CNTs to 20 mL of DMF, and use an ultrasonic cell disruptor to treat it at 360 W for 50 min in an ice-water bath to obtain an LM-CNT dispersion;

[0083] 2) Add 5 g of TPU to the LM-CNT dispersion obtained in step 1), heat and stir in an oil bath at 55 °C for 12 h to obtain a spinning solution;

[0084] 3) Load the spinning solution obtained in step 2) into a syringe with a pushing speed of 8 mL / min and a needle inner diameter of 0.2 mm. After wet spinning in the first coagulation bath, draw it out and directly introduce it into the second coagulation bath for continuous spinning. The first coagulation bath is water at a temperature of 10 °C, and the second coagulation bath is an ethanol / water mixture at 35 °C with a volume ratio of ethanol to water of 4:6. Apply a DC electric field of 3 V / cm in the second coagulation bath -1 , and dry the obtained fibers at room temperature to obtain LM / CNTs / TPU composite fibers;

[0085] The remaining steps are the same as those in Example 1 to obtain LM / CNTs / TPU / PPy-2 composite functional fiber material.

[0086] Example 3

[0087] 1) Add 0.8 g of gallium-indium-tin alloy LM and 0.1 g of CNTs into 20 mL of DMF. Under an ice-water bath, use an ultrasonic cell disruptor to process for 40 min at 340 W to obtain an LM-CNT dispersion;

[0088] 2) Add 5 g of TPU into the LM-CNT dispersion obtained in step 1), heat and stir in an oil bath at 55 °C for 8 h to obtain a spinning solution;

[0089] 3) Load the spinning solution obtained in step 2) into a syringe, with a pushing speed of 8 mL / min and a needle inner diameter of 0.2 mm. After wet spinning in the first coagulation bath, lead it out and directly introduce it into the second coagulation bath to continue spinning. The first coagulation bath is water with a temperature of 10 °C, and the second coagulation bath is an ethanol / water mixed solution at 35 °C with a volume ratio of ethanol to water of 5:5. Apply a DC electric field of 3 V / cm in the second coagulation bath -1 , and dry the obtained fibers at room temperature to obtain LM / CNTs / TPU composite fibers;

[0090] The remaining steps are the same as those in Example 1 to obtain an LM / CNTs / TPU / PPy-3 composite functional fiber material.

[0091] Example 4

[0092] 1) Add 0.8 g of gallium-indium-tin alloy LM and 0.1 g of CNTs into 30 mL of DMF. Under an ice-water bath, use an ultrasonic cell disruptor to process for 50 min at 350 W to obtain an LM-CNT dispersion;

[0093] 2) Add 7 g of TPU into the LM-CNT dispersion obtained in step 1), heat and stir in an oil bath at 55 °C for 10 h to obtain a spinning solution;

[0094] 3) Load the spinning solution obtained in step 2) into a syringe, with a pushing speed of 8 mL / min and a needle inner diameter of 0.2 mm. After wet spinning in the first coagulation bath, lead it out and directly introduce it into the second coagulation bath to continue spinning. The first coagulation bath is water with a temperature of 10 °C, and the second coagulation bath is an ethanol / water mixed solution at 35 °C with a volume ratio of ethanol to water of 5:5. Apply a DC electric field of 3 V / cm in the second coagulation bath -1 , and dry the obtained fibers at room temperature to obtain LM / CNTs / TPU composite fibers;

[0095] The remaining steps are the same as those in Example 1 to obtain an LM / CNTs / TPU / PPy-4 composite functional fiber material.

[0096] Comparative Example 1

[0097] Preparation method of TPU fiber, comprising the following steps:

[0098] 1) Add 7 g of TPU to 20 mL of DMF, heat and stir in an oil bath at 55 °C for 12 h to obtain a spinning solution;

[0099] 2) Load the spinning solution obtained in step 1) into a syringe for wet spinning, with a pushing speed of 8 mL / min and a needle inner diameter of 0.2 mm to obtain TPU fiber.

[0100] Comparative example 2

[0101] Preparation method of LM / CNTs / TPU fiber, comprising the following steps:

[0102] 1) Add 0.6 g of LM and 0.1 g of CNTs to 20 mL of DMF, and treat with a ultrasonic cell disruptor at 360 W for 50 min in an ice-water bath to obtain an LM-CNT dispersion;

[0103] 2) Add 5 g of TPU to the LM-CNT dispersion obtained in step 1), heat and stir in an oil bath at 55 °C for 12 h to obtain a spinning solution;

[0104] 3) Load the spinning solution obtained in step 2) into a syringe, with a pushing speed of 8 mL / min and a needle inner diameter of 0.2 mm. After wet spinning in a first coagulation bath, lead it out and directly introduce it into a second coagulation bath for continuous spinning. The first coagulation bath is water with a temperature of 10 °C, and the second coagulation bath is an ethanol / water mixture at 35 °C with a volume ratio of ethanol to water of 4:6. Apply a DC electric field of 3 V / cm -1 in the second coagulation bath, and dry the obtained fiber at room temperature to obtain LM / CNTs / TPU composite fiber.

[0105] Comparative example 3

[0106] 1) Add 0.6 g of LM (with a mass fraction of 68% Ga, 22% In, 10% Sn, Dongguan Dingguan Metal Technology Co., Ltd.) and 0.1 g of CNTs to 20 mL of DMF, and treat with a ultrasonic cell disruptor at 360 W for 50 min in an ice-water bath to obtain an LM-CNT dispersion;

[0107] 2) Add 5 g of TPU to the LM-CNT dispersion obtained in step 1), heat and stir in an oil bath at 55 °C for 12 h to obtain a spinning solution;

[0108] 3) Load the spinning solution obtained in step 2) into a syringe for wet spinning. The pushing speed is 8 mL / min, the inner diameter of the needle is 0.2 mm, the coagulation bath is water, and the temperature is 10 °C. Dry the obtained fibers at room temperature to obtain LM / CNTs / TPU composite fibers;

[0109] The remaining steps are the same as those in Example 1 to obtain the LM / CNTs / TPU / PPy-5 composite functional fiber material.

[0110] Characterization and performance testing

[0111] Figure 2 SEM images of TPU(a-b) in Comparative Example 1 and LM / CNTs / TPU(c-d) in Comparative Example 2 at different magnifications. As Figure 2 shown, the cylindrical TPU fibers encapsulate the LM and CNTs nanomaterials, preventing the leakage problem caused by the fluidity of LM, providing a reliable guarantee for the practical application of the material.

[0112] Figure 3 SEM images of the LM / CNTs / TPU / PPy-2 composite functional fiber material in Example 2, where (a) and (c) are SEM images at 800 μm, (b) is a partial enlarged view of (a), and (d) is a partial enlarged view of (c). From Figure 3 it can be seen that after the surface of TPU is treated by in-situ polymerization of Py, the fiber surface shows obvious roughening characteristics, with large-area nanoscale granular protrusions distributed. These characteristics fully prove that Py has been successfully loaded on the fiber surface. A tight bonding interface is formed between the Py particles and the fiber matrix, and no obvious phase separation phenomenon appears, indicating good compatibility between Py and the matrix material.

[0113] Figure 4 EDS energy spectrum diagrams of the LM / CNTs / TPU / PPy-2 composite functional fiber material in Example 2. Among them, (a) is the total EDS energy spectrum of LM / CNTs / TPU / PPy-2, and (b-f) represent the element distribution diagrams of Ga, In, Sn, N, and C in turn; Figure 4 It shows the element distribution on the fiber surface, mainly the characteristic peaks of five elements: Ga, In, Sn, O, N, and C. The distribution of these elements provides important experimental basis for the composition and structure of the composite fibers.

[0114] Figure 5XRD patterns of the TPU fiber in Comparative Example 1, the LM / CNTs / TPU fiber in Comparative Example 2, and the LM / CNTs / TPU / PPy-2 fiber in Example 2. It is further confirmed that LM and CNTs are coated inside TPU. As an amorphous polymer, the formation of PPy on the surface or inside of TPU covers some areas of PU, resulting in a decrease in the crystallinity of PU. The above results indicate that Py is effectively polymerized on the TPU matrix.

[0115] The mechanical properties of the fibers in Example 2 and Comparative Examples 1-3 were tested by the single-fiber tensile test method, and the results are shown in Figure 6 . From Figure 6 it can be seen that the stress and strain capabilities of the LM / CNTs / TPU / PPy-2 fiber reach the highest (1.7 MPa and 324%). TPU provides the deformation ability, LM and CNTs fill the pores, the fluidity of LM and the high aspect ratio of CNTs synergistically improve the mechanical properties of the fiber, and the intermolecular bond interaction between PPy and TPU improves the tensile strength of the fiber, and its strain can reach up to about 330% at most. When there is no filling of LM and CNTs, the tensile stress and elongation at break of the pure TPU fiber in Comparative Example 1 are reduced to 0.6 MPa and 122% respectively, because the interior of the pure TPU is a hollow structure, lacking LM to improve the ductility and toughness of the TPU fiber, and the high aspect ratio and excellent mechanical properties of CNTs contribute to stress transfer and improve the uniformity of stress distribution, enabling it to withstand greater deformation during stretching without easy fracture. After filling with LM and CNTs, the mechanical properties of the LM / CNTs / TPU fiber in Comparative Example 2 are improved compared with the TPU fiber, and the elongation at break reaches 322%. It shows that the synergistic effect of LM and CNTs is obvious in improving the stress-strain performance of TPU fibers, which can significantly improve the mechanical properties, improve the stress distribution, and enhance the strain ability. The tensile stress of the LM / CNTs / TPU / PPy-5 fiber in Comparative Example 3 is only 0.7 MPa, much lower than that of the LM / CNTs / TPU / PPy-2 fiber in Example 2. The reason is that ethanol can reduce the swelling degree of TPU, promote the migration of LM into the fiber interior, and form a uniform and continuous core-shell interface. With only a single water coagulation bath, the LM inside the fiber without the second coagulation bath is prone to agglomeration, uneven distribution along the fiber length, and thus leads to uneven stress.

[0116] The LM / CNTs / TPU / PPy-2 composite functional fiber material LM / CNTs / TPU / PPy prepared in Example 2 was connected to a 1.5 V battery in series to form an electrically conductive path, and an LED small light bulb could be lit, as shown in Figure 7 . From Figure 7It can be seen that LM and CNTs form a continuous conductive network, which can significantly improve the conductivity. The fluidity of LM enables the resistance change rate of the material to be less than 10% during stretching. The electricity generated by the fiber during stretching can light up an LED lamp. LM can also fill the cracks caused by deformation and restore the conductive path.

[0117] Figure 8 It is the conductivity graph of the TPU fiber (a) in Comparative Example 1 and the LM / CNTs / TPU fiber (b) in Comparative Example 2. From Figure 8 It can be seen that the TPU fiber does not have conductivity because it is not filled with the conductive substances LM and CNTs. Py is not polymerized on the surface of the LM / CNTs / TPU, and the overall conductivity of the fiber is poor. Therefore, neither of them can light up an LED bulb.

[0118] Figure 9 It is the woven physical diagram of the LM / CNTs / TPU / PPy-2 composite functional fiber material in Example 2, indicating that the prepared fiber has flexible weavability.

[0119] Figure 10 It is the sensing performance graph of the LM / CNTs / TPU / PPy-2 composite functional fiber material in different human body parts in Example 2. The LM / CNTs / TPU / PPy-2 fiber is fixed on the joints of various parts of the human body, and a series of motion tests are carried out, such as (a) fingers, (b) arms, (c) eyebrows, (d) back of the neck, (e) throat, (f) ankles. The real-time resistance of the fiber sensor is measured and recorded by a VC8256A digital multimeter (Shenzhen Victory High Electronic Technology Co., Ltd., China) to detect the relative resistance change of the LM / CNTs / PU / PPy-2 fiber during small and large-amplitude movements. The results are as Figure 10 shown. As the movement amplitudes of (a) fingers, (b) arms, and (c) eyebrows increase, the fiber resistance increases accordingly. When the tester repeatedly changes the movements of (d) neck, (e) throat, and (f) feet, the LM / CNTs / TPU / PPy-2 clearly monitors and measures each cycle of the movement. The above tests show that the LM / CNTs / TPU / PPy-2 has durability, high stability, and strain sensitivity, enabling it to quickly respond to external deformations and convert mechanical signals into electrical signals, thus realizing a highly sensitive sensing function.

[0120] Figure 11 It is the sound absorption performance graph of the LM / CNTs / TPU / PPy-2 composite functional fiber material in Example 2. The Figure 9 woven fabric physical object on the right side in is stacked layer by layer, two layers of the same formed fabrics are stacked up and down, and three layers of the same formed fabrics are stacked up and down to form a single-layer fabric, a double-layer composite fabric, and a three-layer composite fabric in turn, and the sound absorption performance is tested. As Figure 11As shown, as the number of layers of the composite fabric increases, the sound absorption efficiency approaches 1, and the sound absorption effect gradually improves.

[0121] Figure 12 Figure (a) is the triboelectric generation schematic diagram of the LM / CNTs / TPU / PPy-2 composite functional fiber material in Example 2. Initially, the complete contact between TPU and cotton yarn generates surface charges (i) at their interface due to contact electrification. According to the tested triboelectric series, electrons transfer from cotton fibers to the TPU surface because cotton is more triboelectrically positive than TPU. At this time, the opposite equivalent charges are completely balanced, and there is no electron flow in the external circuit. Since TPU is an insulating material, the generated negative charges can be stored on its surface for a long time. When the warp and weft yarns start to separate, the potential of the LM electrode increases due to electrostatic induction, and the potential difference between LM and the ground drives electrons to flow from LM to the ground through the external circuit. Therefore, LM gradually becomes positively charged (ii). The cotton yarn moves away from the TPU surface until the positive charges induced on LM balance the negative charges on the outer shell surface, reaching the electrostatic equilibrium state (iii). Then, when the warp and weft yarns approach again, electrons flow back from the ground to the LM electrode to compensate for the potential difference, generating a reverse current (iv), driving the AC output cycle until the system returns to state (i). Through the action of periodic external forces, continuous contact-separation occurs between the cotton yarn and TPU, resulting in repeated charge transfer and electrostatic induction, thus generating an alternating current in the external circuit and achieving the conversion of mechanical energy to electrical energy.

[0122] Figure 13 Figure (b) is the triboelectric generation performance diagram of the LM / CNTs / TPU / PPy-2 composite functional fiber material in Example 2, where (a-c) represent the open-circuit voltage (VOC) under the conditions of 1 Hz, 2 Hz, and 3 Hz in sequence, (d-f) represent the short-circuit current (ISC) under the conditions of 1 Hz, 2 Hz, and 3 Hz in sequence, and (g-i) represent the short-circuit charge transfer (QSC) under the conditions of 1 Hz, 2 Hz, and 3 Hz in sequence. By applying a contact force of 20 N at different frequencies to study the constructed fabric ( Figure 9 the right woven fabric in Figure 13 ), as the contact frequency increases from 1 Hz to 3 Hz, the short-circuit current (ISC) ( Figure 13 in (d-f)) also increases, reaching a maximum of 30 nA. However, the open-circuit voltage (VOC) ( Figure 13 in (a-c)) and the short-circuit charge transfer (QSC) (

[0123] in (g-i)) are independent of frequency, reaching a maximum of 9 V and 3 nC respectively. The triboelectric generation performance of the fabric remains stable, indicating that the device can continuously and stably collect biomechanical energy. Figures 10 - 13It can be seen that the composite functional fiber of the present invention can be used in the fields of flexible sensors, smart textiles, health detection systems, etc.

[0124] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A preparation method of a liquid metal-carbon nanotube-polyurethane-polypyrrole composite functional fiber material, characterized in that, It includes the following steps: Mix liquid metal, carbon nanotubes and organic solvent, and disperse them to obtain a liquid metal-carbon nanotube dispersion; Heat and mix the liquid metal-carbon nanotube dispersion with polyurethane to obtain a spinning solution; Perform wet spinning of the spinning solution in a first coagulation bath and a second coagulation bath in sequence, and apply a DC electric field in the second coagulation bath to obtain LM / CNTs / TPU composite conductive fibers; Mix pyrrole, p-toluenesulfonic acid and water to obtain a monomer solution; Immerse the LM / CNTs / TPU composite conductive fibers in the monomer solution, add an oxidant, and carry out a polymerization reaction to obtain a liquid metal-carbon nanotube-polyurethane-polypyrrole composite functional fiber material.

2. The preparation method according to claim 1, wherein, The liquid metal includes one or several of gallium indium alloy, gallium indium tin alloy and gallium tin alloy.

3. The preparation method according to claim 1 or 2, characterized in that, The mass ratio of the liquid metal to the carbon nanotubes is 4-8:1-2; the mass ratio of the polyurethane to the liquid metal is 50-100:4-8.

4. The preparation method according to claim 3, characterized in that, The dispersion is carried out under ultrasonic conditions, the power of the ultrasonic is 270-540W, and the time is 20-50min; the temperature of the heat mixing is 50-60°C, and the time is 4-12h.

5. The preparation method according to claim 1, wherein The first coagulation bath is water, and the temperature of the first coagulation bath is 5-15°C; the second coagulation bath is an ethanol-water mixture, and the temperature of the second coagulation bath is 30-40°C.

6. The preparation method according to claim 1 or 5, characterized in that The electric field strength of the DC electric field is 1 to 5 V / cm -1 ; The advancing speed of the wet spinning is 5 to 8 mL / min -1 .

7. The preparation method according to claim 1, characterized in that, The dosage ratio of pyrrole, p-toluenesulfonic acid and water is 0.3-0.5mL:0.4-0.6g:20-40mL; the oxidant includes iron salt, ammonium persulfate or H2O2; the dosage ratio of the oxidant to pyrrole is 0.67-1.07g:0.3-0.5mL.

8. The preparation method according to claim 1 or 7, characterized in that, The temperature of the polymerization reaction is 0-8°C, and the polymerization time is 5-8h.

9. A liquid metal-carbon nanotube-polyurethane-polypyrrole composite functional fiber material prepared by the preparation method according to any one of claims 1-8.

10. Application of the liquid metal-carbon nanotube-polyurethane-polypyrrole composite functional fiber material according to claim 9 in the fields of resistive strain sensors, triboelectric power generation or sound absorption.

Images