Preparation method of conductive composite fiber based on graphene and graphene quantum dot bridge

Abstract

The application relates to the technical field of intelligent materials, in particular to a conductive composite fiber based on graphene and graphene quantum dot bridging and a preparation method thereof. The application precisely regulates the spherical morphology of graphene quantum dots through a hierarchical ultrasonic-freezing template method, constructs a micron-level groove structure on the surface of a hybrid material by using plasma etching-mechanical embedding, forms a'mortise and tenon' type interface reinforced composite through the synergistic action of physical embedding-pi stacking, and finally realizes the axial directional arrangement of a conductive network by combining airflow field regulation spinning. The application adopts physical means throughout the process, ensures the safety of the material, and the obtained fiber has fast photo-thermal response, high conductivity and excellent stability, the preparation method is simple, and the application is suitable for industrial production.

Description

Technical Field

[0001] This invention relates to the field of smart materials technology, and mainly to a composite fiber, specifically to a method for preparing a conductive composite fiber based on graphene and graphene quantum dot bridging. Background Technology

[0002] Photothermal responsive smart fibers have wide applications in solar energy utilization, smart temperature-controlled textiles, and wearable devices, enabling efficient conversion of light energy into heat energy and achieving adaptive temperature regulation and sensing functions. With increasing demands for green environmental protection and health safety, the development of non-toxic, harmless, and highly biocompatible smart materials has become a research focus. Traditional methods often rely on chemical modification or rare-earth doping, which, while achieving certain functions, pose environmental risks, poor biocompatibility, and involve complex preparation processes, making it difficult to meet the needs of large-scale industrial production.

[0003] Existing methods for preparing photothermal responsive fibers mainly include chemical reduction, solvothermal methods, or simple physical mixing methods. For example, some methods enhance photothermal performance by chemically modifying graphene or adding metal nanoparticles, but this may introduce harmful chemical residues, affecting safety. Other purely physical methods, such as mechanical blending, avoid chemical contamination, but lack precise morphology control, resulting in disordered internal conductive networks, slow photothermal response, and poor stability under high humidity and high temperature environments, easily leading to performance degradation. The drawback of these methods is that they cannot simultaneously achieve high performance, high safety, and controllable preparation, limiting their practical applications.

[0004] This invention employs a fully physical process, precisely controlling the morphology of graphene and its composites through the synergistic effects of multiple physical fields, including graded ultrasonication-cryogenic template, plasma etching-mechanical interlocking, physical interlocking-π stacking, and airflow-controlled spinning, thus avoiding any chemical reactions. The key feature of this invention is the construction of a "mortise and tenon" interlocking structure between spherical graphene quantum dots and grooved hybrid materials, achieving axial directional alignment during spinning, thereby producing smart fibers with fast photothermal response, excellent conductivity, and high stability. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for preparing conductive composite fibers based on graphene and graphene quantum dot bridging, the specific preparation steps of which are as follows: S1. Preparation of spherical graphene quantum dots: Weigh 1-5 g of graphite powder and slowly add it to 150-250 mL of deionized water. Place the mixture on a magnetic stirrer and stir at 200-400 rpm for 10-20 min at room temperature to form a preliminary suspension. Transfer it to an ultrasonic cleaner with a power of 80-120 W, set the temperature to 20-30℃, and sonicate for 20-40 min to exfoliate the graphite into thin layers of graphene using weak shear force. Then, transfer the suspension to a variable-power ultrasonic cell disruptor equipped with a 20-30℃ constant temperature device. Use gradient power mode, first sonicate at 200-400 W for 20-40 min, then sonicate at 300-500 W for 20-40 min, with pulse parameters set to 1-3 s working and 2-4 s intermittent, to precisely break the graphene sheets through cavitation effect. Afterward, quickly transfer the dispersion to a freeze dryer, set the temperature to -50 to -30℃. Freeze at ℃ for 3-5 hours to utilize the template effect of ice crystals during freeze-drying to prevent graphene sheets from re-accumulating and forming a highly dispersed spherical structure. After freezing, centrifuge at 8000-12000 rpm for 10-20 min using a high-speed refrigerated centrifuge to remove agglomerates larger than 20 nm and collect the supernatant. Finally, screen 15-20 nm spherical graphene quantum dots through membrane filtration and collect them for later use. This step, through graded ultrasonication and freeze-templation, precisely controls the size and morphology of graphene quantum dots to obtain a highly uniform spherical structure, thereby enhancing the specific surface area and dispersibility of quantum dots and providing an ideal base material for subsequent interfacial bonding, avoiding agglomeration problems caused by irregular morphology.

[0006] S2. Preparation of grooved graphene-carbon nanotube hybrid materials: Weigh 2-4 g of graphene sheets and 0.5-1.5 g of multi-walled carbon nanotubes, mix them, and place them in a low-temperature plasma treatment instrument, then evacuate to 10°C. -3 -10 -2Argon gas is introduced at a flow rate of 8-12 L / min, maintaining a pressure of 40-60 Pa. The plasma power is set to 70-90 W, and the etching time to 8-12 min, using high-energy particle bombardment to form trench structures 100-200 nm wide. Then, the etching material and 0.03-0.07 g of bio-based wax dispersant are added to 120-180 mL of anhydrous ethanol and stirred to form a suspension. This suspension is then transferred to a high-speed mill at 7000-9000 rpm for 10-20 min to embed carbon nanotubes into the graphene trenches. The mixture is then sonicated at 350-450 W for 20-40 min using an ultrasonic cell disruptor to enhance dispersion. Finally, the mixture is filtered using a vacuum filtration device with a 0.22 μm pore size, and the filter cake is dried in a vacuum drying oven at 70-90 ℃ for 1-3 minutes. h, a grooved hybrid material is obtained; this step uses plasma etching to create micron-scale trenches on the graphene surface, and fixes carbon nanotubes in the trenches through mechanical intercalation to form a stable hybrid structure, thereby enhancing the interfacial bonding force and dispersion stability of the material, providing anchoring points for subsequent quantum dot embedding, and improving the mechanical strength of the overall conductive network.

[0007] S3. Construction of the interface-strengthening composite: Weigh 1-2 g of the spherical graphene quantum dots obtained in step S1 and 3-5 g of the grooved hybrid material obtained in step S2, and add them together to 120-180 mL of deionized water; first place the mixture in a vortex mixer at 2500-3500 rpm for 8-12 min to initially disperse it; then transfer it to an ultrasonic cleaner at 450-550 W for 15-25 min to ensure that the quantum dots are evenly distributed in the grooves; then inject the mixture into a high-pressure homogenizer at 40-60 MPa and cycle it 4-6 times to use high pressure to embed the quantum dots into the grooves, forming a tenon-and-mortise structure; then let it stand at 20-30℃ for 1-3 h to stabilize the interface through π-π stacking; finally, centrifuge at 10000-14000 rpm for 15-25 min, wash, and vacuum dry at 70-90℃ for 2-4 hours. h, an interface-strengthened composite is obtained; this step, through a closed-loop process of "size adaptation - preliminary dispersion - precise embedding - interface stabilization - purification and drying", utilizes the size complementary characteristics of quantum dots, carbon nanotubes and trenches, combined with the synergistic effect of physical interlocking and π-π stacking, to construct a robust "mortise and tenon" interface, significantly improving the interface shear strength and conductivity efficiency, thereby constructing a highly efficient three-dimensional conductive network and avoiding network breakage or performance degradation.

[0008] S4. Spinning preparation of smart fibers: Weigh 6-10 g of the composite obtained in step S3 and 0.3-0.5 g of silane coupling agent KH550, add them to a high-speed mixer, set the speed to 1400-1600 rpm and the temperature to 70-90 ℃, pre-treat for 4-6 min to coat the fibers with the coupling agent; then add 120-180 g of polyamide 6 chips and 8-10 g of thermoplastic polyurethane, adjust the speed to 1900-2100 rpm and the temperature to 85-95 ℃, mix for 8-12 min; then add the mixture to a twin-screw extruder, set the feed section temperature to 210-230 ℃, the melt section temperature to 240-260 ℃, the die head section temperature to 250-270 ℃, and the screw speed to 280-320 rpm, melt blend and then extrude and granulate to obtain fibers with a diameter of 2-3 mm. The composite masterbatch is prepared in mm. The masterbatch is added to a vertical melt spinning machine, with the spinning temperature controlled at 230-250℃. Nitrogen gas at 260-280℃ is introduced at a flow rate of 6-10 m / s, and the drafting roller speed is 350-450 rpm with a hot draw ratio of 2.5:1-3.5:1 to guide the directional alignment of the conductive network inside the fiber. The spun fiber is then treated with a heat-setting roller at 110-130℃ for 20-40 seconds, and wound at a winding machine speed controlled at 450-550 m / min. This step utilizes the synergistic control of airflow and hot draw to achieve the axial directional alignment of the conductive network in the fiber, thereby optimizing the photothermal conversion path and electron transport efficiency, ensuring the fiber has rapid response and high stability, while improving compatibility through physical coating.

[0009] Preferably: In step S1, 1 g of graphite powder is weighed and slowly added to 150 mL of deionized water. The mixture is placed on a magnetic stirrer and stirred at 200 rpm for 10 min at room temperature to form a preliminary suspension. This suspension is then transferred to an 80 W ultrasonic cleaner, set to 20°C, and ultrasonically treated for 20 min to exfoliate the graphite into thin layers of graphene using weak shear force. The suspension is then transferred to a variable-power ultrasonic cell disruptor equipped with a 20°C constant temperature device. A gradient power mode is used, first ultrasonicating at 200 W for 20 min, then at 300 W for 20 min, with pulse parameters set to 1 s working and 2 s intermittent. This precisely breaks down the graphene sheets through cavitation. The dispersion is then rapidly transferred to a freeze dryer, set to -50°C, and frozen for 3 h. The template effect of ice crystals during freeze-drying prevents the graphene sheets from re-accumulating, forming a highly dispersed spherical structure. After freezing, the mixture is centrifuged at 8000-12000 rpm. Centrifuge at rpm for 10-20 min to remove aggregates with a particle size greater than 20 nm and collect the supernatant; finally, screen out 15-20 nm spherical graphene quantum dots through membrane filtration and collect them for later use.

[0010] Preferably: In step S2, 2 g of graphene sheets and 0.5 g of multi-walled carbon nanotubes are weighed, mixed, and placed in a low-temperature plasma treatment instrument, which is then evacuated to 10°C. -3 Argon gas was introduced at a flow rate of 8 L / min, maintaining a pressure of 40 Pa. The plasma power was set to 70 W, and the etching time was 8 min. High-energy particle bombardment was used to form a groove structure with a width of 100-200 nm. Then, the etched material and 0.03 g of bio-based wax dispersant were added to 120 mL of anhydrous ethanol and stirred to form a suspension. The suspension was transferred to a high-speed mill and processed at 7000 rpm for 10 min to embed carbon nanotubes into the graphene grooves. The dispersion was then enhanced by ultrasonic cell disruption at 350 W for 20 min. Finally, the mixture was filtered using a vacuum filtration device with a pore size of 0.22 μm. The filter cake was dried in a vacuum drying oven at 70 °C for 1 h to obtain the grooved hybrid material.

[0011] Preferably: In step S2, 3 g of graphene sheets and 1.0 g of multi-walled carbon nanotubes are weighed, mixed, and then placed in a low-temperature plasma treatment instrument, and the vacuum is evacuated to 5 × 10⁻⁶. -3 Argon gas was introduced at a flow rate of 10 L / min, maintaining a pressure of 50 Pa. The plasma power was set to 80 W, and the etching time to 10 min, using high-energy particle bombardment to form a groove structure 100-200 nm wide. Then, the etched material and 0.05 g of bio-based wax dispersant were added to 150 mL of anhydrous ethanol and stirred to form a suspension. The suspension was transferred to a high-speed mill at 8000 rpm for 15 min to embed carbon nanotubes into the graphene grooves. The dispersion was then enhanced by ultrasonic cell disruption at 400 W for 30 min. Finally, the mixture was filtered using a vacuum filtration device with a pore size of 0.22 μm. The filter cake was dried in a vacuum drying oven at 80 °C for 2 h to obtain the grooved hybrid material.

[0012] Preferably: In step S3, 1.5 g of the spherical graphene quantum dots obtained in step S1 and 4 g of the grooved hybrid material obtained in step S2 are weighed and added together to 150 mL of deionized water; the mixture is first placed in a vortex mixer at 3000 rpm for 10 min to initially disperse the particles; then transferred to an ultrasonic cleaner at 500 W for 20 min to ensure that the quantum dots are evenly distributed in the grooves; the mixture is then injected into a high-pressure homogenizer at 50 MPa and cyclically processed 5 times to embed the quantum dots into the grooves using high pressure, forming a tenon-and-mortise structure; subsequently, the mixture is allowed to stand at 25 °C for 2 h to stabilize the interface through π-π stacking; finally, it is centrifuged at 12000 rpm for 20 min, washed, and then vacuum dried at 80 °C for 3 h to obtain the interface-reinforced composite.

[0013] Preferably: In step S3, 1 g of the spherical graphene quantum dots obtained in step S1 and 3 g of the grooved hybrid material obtained in step S2 are weighed and added together to 120 mL of deionized water; the mixture is first placed in a vortex mixer at 2500 rpm for 8 min to initially disperse the particles; then it is transferred to an ultrasonic cleaner at 450 W for 15 min to ensure that the quantum dots are evenly distributed in the grooves; the mixture is then injected into a high-pressure homogenizer at 40 MPa and cyclically processed 4 times to embed the quantum dots into the grooves using high pressure, forming a tenon-and-mortise structure; subsequently, it is allowed to stand at 20 °C for 1 h to stabilize the interface through π-π stacking; finally, it is centrifuged at 10000 rpm for 15 min, washed, and then vacuum dried at 70 °C for 2 h to obtain the interface-reinforced composite.

[0014] Preferably: In step S4, 6 g of the composite obtained in step S3 and 0.3 g of silane coupling agent KH550 are weighed and added to a high-speed mixer. The speed is set to 1400 rpm and the temperature is controlled at 70 ℃. Pretreatment is performed for 4 min to coat the coupling agent. Then, 120 g of polyamide 6 chips and 8 g of thermoplastic polyurethane are added. The speed is adjusted to 1900 rpm and the temperature to 85 ℃. Mixing is performed for 8 min. The mixture is then added to a twin-screw extruder. The feed section temperature is set to 210 ℃, the melt section temperature to 240 ℃, the die head section temperature to 250 ℃, and the screw speed is 280 rpm. After melt blending, the mixture is extruded and granulated to obtain a composite masterbatch with a diameter of 2 mm. The masterbatch is then added to a vertical melt spinning machine. The spinning temperature is controlled at 230 ℃, and nitrogen gas at 260 ℃ is introduced at a flow rate of 6 m / s. The speed of the drawing roller is 350 rpm. The spun fibers are oriented and arranged using a rpm and a hot draw ratio of 2.5:1. The fibers are then heat-set at 110 ℃ for 20 s, and the winding machine speed is controlled at 450 m / min for winding.

[0015] Preferably, the pharmaceuticals and instruments used in this invention are sourced as follows: Graphite powder was purchased from Qingdao Huatai Graphite Co., Ltd., with a purity ≥99.8%; graphene sheets were purchased from Beijing Boyu High-Tech Materials Co., Ltd., with a sheet diameter of 5-20 μm, number of layers <10, and purity ≥99.5%; multi-walled carbon nanotubes were purchased from Beijing Boyu High-Tech Materials Co., Ltd., with a diameter of 10-20 nm, a length of 10-30 μm, and a purity >98%; bio-based wax dispersant (LY-BW-01) was purchased from Shanghai Luyuan Biotechnology Co., Ltd., with the main component being refined rice bran wax, a melting point of 75-80°C, and a saponification value of 70-90 mg KOH / g; the instruments were sourced from: an ultrasonic cleaner (KQ-100E) purchased from Kunshan Ultrasonic Instrument Co., Ltd., an ultrasonic cell disruptor (JY92-IIN) purchased from Ningbo Xinzhi Biotechnology Co., Ltd., and a high-pressure homogenizer (AH-2010) purchased from ATS Engineering, Canada. Ltd.; the plasma treatment instrument (PT-0.5S) was purchased from Beijing Zhongke Instruments, and the high-speed mixer (SHR-10A) was purchased from Zhangjiagang Light Industry Machinery Factory.

[0016] Advantages of this invention: 1. This invention avoids chemical residues and harmful substances through a fully physical process, ensuring the safety and high biocompatibility of the material. At the same time, by utilizing the synergistic regulation of multiple physical fields, it achieves precise control over the spherical morphology of graphene quantum dots and the groove structure of hybrid materials, thereby significantly improving the specific surface area and interfacial bonding efficiency of the material, laying the structural foundation for high-performance fibers.

[0017] 2. This invention constructs a "mortise and tenon" type physical interlocking interface. Through the synergistic effect of high-pressure homogenization and π-π stacking, the bonding strength between quantum dots and hybrid materials is enhanced, effectively suppressing interface slippage and network breakage. This results in an order-of-magnitude improvement in the conductivity and photothermal response speed of the fiber, and also provides excellent durability.

[0018] 3. The airflow spinning process of the present invention achieves the directional arrangement of the conductive network along the fiber axis through inert gas guidance and thermal stretching technology, optimizes the electron and phonon transport paths, thereby improving photothermal conversion efficiency and mechanical properties. At the same time, the method is simple and controllable, suitable for large-scale industrial production, and reduces energy consumption and cost.

[0019] 4. The smart fiber obtained by this invention exhibits rapid photothermal response and stable conductivity while maintaining high safety, and has broad application prospects in the fields of smart textiles, wearable devices and medical temperature control. Attached Figure Description

[0020] Figure 1 This is a SEM image of the spherical graphene quantum dots prepared in Example 1 of the present invention.

[0021] Figure 2 This is a SEM image of the spherical graphene quantum dots prepared in Comparative Example 1 of this invention.

[0022] Figure 3 This is a SEM image of the spherical graphene quantum dots prepared in Comparative Example 2 of this invention.

[0023] Figure 4 This is a SEM image of the spherical graphene quantum dots prepared in Comparative Example 3 of this invention.

[0024] Figure 5 This is a SEM image of the interface-strengthening composite prepared in Example 1 of the present invention.

[0025] Figure 6 The actual product of the fiber obtained in Example 1 of this invention. Figure 1 .

[0026] Figure 7 The actual product of the fiber obtained in Example 1 of this invention. Figure 2 .

[0027] Figure 8 The product of the fiber obtained by the present invention is a fabric obtained by further processing and weaving into cloth. Figure 1 .

[0028] Figure 9 The product of the fiber obtained by the present invention is a fabric obtained by further processing and weaving into cloth. Figure 2 . Detailed Implementation

[0029] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0030] Example 1

[0031] S1. Preparation of quasi-spherical graphene quantum dots: Weigh 1 g of graphite powder and slowly add it to 150 mL of deionized water. Place the mixture on a magnetic stirrer and stir at 200 rpm for 10 min at room temperature to form a preliminary suspension. Transfer it to an 80 W ultrasonic cleaner, set the temperature to 20℃, and sonicate for 20 min to exfoliate the graphite into thin layers of graphene using weak shear force. Then, transfer the suspension to a variable power ultrasonic cell disruptor equipped with a 20℃ constant temperature device. Use gradient power mode, first sonicate at 200 W for 20 min, then at 300 W for 20 min, with pulse parameters set to 1 s working and 2 s intermittent, to precisely break the graphene sheets through cavitation effect. Afterward, quickly transfer the dispersion to a freeze dryer, set the temperature to -50℃, and freeze for 3 h. Utilize the template effect of ice crystals during freeze drying to prevent the graphene sheets from recombining, forming a highly dispersed quasi-spherical structure. After freezing, centrifuge at 8000 rpm for 10 minutes using a high-speed refrigerated centrifuge. The process involves removing agglomerates larger than 20 nm and collecting the supernatant. Finally, 15-20 nm spherical graphene quantum dots are screened out by membrane filtration and collected for later use. This step uses graded ultrasonication and a frozen template method to precisely control the size and morphology of graphene quantum dots, obtaining a highly uniform spherical structure, thereby enhancing the specific surface area and dispersibility of the quantum dots, providing an ideal base material for subsequent interfacial bonding, and avoiding agglomeration problems caused by irregular morphology.

[0032] S2. Preparation of grooved graphene-carbon nanotube hybrid material: Weigh 2 g of graphene sheet and 0.5 g of multi-walled carbon nanotube, mix them, and place them in a low-temperature plasma treatment instrument. Evacuate to 10 °C. -3 Argon gas was introduced at a flow rate of 8 L / min, maintaining a pressure of 40 Pa. The plasma power was set to 70 W, and the etching time to 8 min, using high-energy particle bombardment to form trench structures 100-200 nm wide. Then, the etching material and 0.03 g of bio-based wax dispersant were added to 120 mL of anhydrous ethanol and stirred to form a suspension. This suspension was transferred to a high-speed mill at 7000 rpm for 10 min to embed carbon nanotubes into the graphene trenches. The mixture was then sonicated at 350 W for 20 min using an ultrasonic cell disruptor to enhance dispersion. Finally, the mixture was filtered using a vacuum filtration device with a 0.22 μm pore size, and the filter cake was dried in a vacuum drying oven at 70 °C for 1 minute. h, a grooved hybrid material is obtained; this step uses plasma etching to create micron-scale trenches on the graphene surface, and fixes carbon nanotubes in the trenches through mechanical intercalation to form a stable hybrid structure, thereby enhancing the interfacial bonding force and dispersion stability of the material, providing anchoring points for subsequent quantum dot embedding, and improving the mechanical strength of the overall conductive network.

[0033] S3. Construction of the interface-strengthening composite: Weigh 1 g of the spherical graphene quantum dots obtained in step S1 and 3 g of the grooved hybrid material obtained in step S2, and add them together to 120 mL of deionized water. First, place the mixture in a vortex mixer at 2500 rpm for 8 min to initially disperse it. Then, transfer it to an ultrasonic cleaner at 450 W for 15 min to ensure that the quantum dots are uniformly distributed in the grooves. Next, inject the mixture into a high-pressure homogenizer at 40 MPa and cycle it 4 times to embed the quantum dots into the grooves using high pressure, forming a tenon-and-mortise structure. Then, let it stand at 20℃ for 1 h to stabilize the interface through π-π stacking. Finally, centrifuge at 10000 rpm for 15 min, wash, and vacuum dry at 70℃ for 2 h to obtain the interface-strengthening composite. This step uses a closed-loop process of "size adaptation - initial dispersion - precise embedding - interface stabilization - purification and drying" to utilize the size complementarity of quantum dots, carbon nanotubes, and grooves, combined with physical intercalation and π-π stacking. The synergistic effect of stacking creates a robust "mortise and tenon" interface, significantly improving the interface shear strength and conductivity, thereby constructing a highly efficient three-dimensional conductive network and avoiding network breakage or performance degradation.

[0034] S4. Preparation of intelligent fiber spinning: Weigh 6 g of the composite obtained in step S3 and 0.3 g of silane coupling agent KH550, add them to a high-speed mixer, set the speed to 1400 rpm and the temperature to 70 ℃, pre-treat for 4 min to coat the coupling agent; then add 120 g of polyamide 6 chips and 8 g of thermoplastic polyurethane, adjust the speed to 1900 rpm and the temperature to 85 ℃, mix for 8 min; then add the mixture to a twin-screw extruder, set the feed section temperature to 210 ℃, the melt section temperature to 240 ℃, the die head section temperature to 250 ℃, and the screw speed to 280 rpm, melt blend and then extrude and granulate to obtain a composite masterbatch with a diameter of 2 mm; add the masterbatch to a vertical melt spinning machine, control the spinning temperature to 240 ℃, introduce 260 ℃ nitrogen gas at a flow rate of 6 m / s, and coordinate with a drafting roller speed of 350 rpm. The spun fibers are oriented with a rpm and a hot draw ratio of 2.5:1, guiding the internal conductive network of the fiber to oriented alignment. The spun fibers are then heat-set at 110 ℃ for 20 s, and wound at a winding machine speed of 450 m / min. The resulting product is as follows: Figure 6 , Figure 7 As shown, this step utilizes the synergistic control of airflow field and thermal stretching to achieve axial orientation of the conductive network in the fiber, thereby optimizing the photothermal conversion path and electron transport efficiency, ensuring that the fiber has fast response and high stability, while improving compatibility through physical coating.

[0035] Example 2

[0036] S1. Preparation of quasi-spherical graphene quantum dots: Weigh 3 g of graphite powder and slowly add it to 200 mL of deionized water. Place the mixture on a magnetic stirrer and stir at 300 rpm for 15 min at room temperature to form a preliminary suspension. Transfer it to a 100 W ultrasonic cleaner, set the temperature to 25℃, and sonicate for 30 min to exfoliate the graphite into thin layers of graphene using weak shear force. Then, transfer the suspension to a variable power ultrasonic cell disruptor equipped with a 25℃ constant temperature device. Use gradient power mode, first sonicate at 300 W for 30 min, then at 400 W for 30 min, with pulse parameters set to 2 s working and 3 s intermittent, to precisely break the graphene sheets through cavitation effect. Afterward, quickly transfer the dispersion to a freeze dryer, set the temperature to -40℃, and freeze for 4 h. Utilize the template effect of ice crystals during freeze drying to prevent the graphene sheets from recombining, forming a highly dispersed quasi-spherical structure. After freezing, centrifuge at 10000 rpm for 15 minutes using a high-speed refrigerated centrifuge. The process involves removing agglomerates larger than 20 nm and collecting the supernatant. Finally, 15-20 nm spherical graphene quantum dots are screened out by membrane filtration and collected for later use. This step uses graded ultrasonication and a frozen template method to precisely control the size and morphology of graphene quantum dots, obtaining a highly uniform spherical structure, thereby enhancing the specific surface area and dispersibility of the quantum dots, providing an ideal base material for subsequent interfacial bonding, and avoiding agglomeration problems caused by irregular morphology.

[0037] S2. Preparation of grooved graphene-carbon nanotube hybrid material: Weigh 3 g of graphene sheet and 1.0 g of multi-walled carbon nanotube, mix them, and place them in a low-temperature plasma treatment instrument. Evacuate to 5 × 10⁻⁶. -3 Argon gas was introduced at a flow rate of 10 L / min, maintaining a pressure of 50 Pa. The plasma power was set to 80 W, and the etching time to 10 min, using high-energy particle bombardment to form trench structures 100-200 nm wide. Then, the etching material and 0.05 g of bio-based wax dispersant were added to 150 mL of anhydrous ethanol and stirred to form a suspension. This suspension was then transferred to a high-speed mill at 8000 rpm for 15 min to embed carbon nanotubes into the graphene trenches. The mixture was then sonicated at 400 W for 30 min using an ultrasonic cell disruptor to enhance dispersion. Finally, the mixture was filtered using a vacuum filtration device with a 0.22 μm pore size, and the filter cake was dried in a vacuum drying oven at 80 °C for 2 hours. h, a grooved hybrid material is obtained; this step uses plasma etching to create micron-scale trenches on the graphene surface, and fixes carbon nanotubes in the trenches through mechanical intercalation to form a stable hybrid structure, thereby enhancing the interfacial bonding force and dispersion stability of the material, providing anchoring points for subsequent quantum dot embedding, and improving the mechanical strength of the overall conductive network.

[0038] S3. Construction of the interface-strengthening composite: Weigh 1.5 g of the spherical graphene quantum dots obtained in step S1 and 4 g of the grooved hybrid material obtained in step S2, and add them together to 150 mL of deionized water. First, place the mixture in a vortex mixer at 3000 rpm for 10 min to initially disperse it. Then, transfer it to an ultrasonic cleaner at 500 W for 20 min to ensure that the quantum dots are uniformly distributed in the grooves. Next, inject the mixture into a high-pressure homogenizer at 50 MPa and cycle it 5 times to embed the quantum dots into the grooves using high pressure, forming a tenon-and-mortise structure. Then, let it stand at 25℃ for 2 h to stabilize the interface through π-π stacking. Finally, centrifuge at 12000 rpm for 20 min, wash, and vacuum dry at 80℃ for 3 h to obtain the interface-strengthening composite. This step uses a closed-loop process of "size adaptation - initial dispersion - precise embedding - interface stabilization - purification and drying" to utilize the size complementarity of quantum dots, carbon nanotubes, and grooves, combined with physical intercalation and π-π stacking. The synergistic effect of stacking creates a robust "mortise and tenon" interface, significantly improving the interface shear strength and conductivity, thereby constructing a highly efficient three-dimensional conductive network and avoiding network breakage or performance degradation.

[0039] S4. Preparation of intelligent fiber spinning: Weigh 8 g of the composite obtained in step S3 and 0.4 g of silane coupling agent KH550, add them to a high-speed mixer, set the speed to 1500 rpm and the temperature to 80 ℃, pre-treat for 5 min to coat the coupling agent; then add 150 g of polyamide 6 chips and 9 g of thermoplastic polyurethane, adjust the speed to 2000 rpm and the temperature to 90 ℃, mix for 10 min; then add the mixture to a twin-screw extruder, set the feed section temperature to 220 ℃, the melt section temperature to 250 ℃, the die head section temperature to 260 ℃, and the screw speed to 300 rpm, melt blend and then extrude and granulate to obtain a composite masterbatch with a diameter of 2.5 mm; add the masterbatch to a vertical melt spinning machine, control the spinning temperature to 240 ℃, introduce 270 ℃ nitrogen gas at a flow rate of 8 m / s, and coordinate with a drafting roller speed of 400 rpm. The spun fibers are oriented and arranged by rpm and a thermal draw ratio of 3.0:1. The fibers are then heat-set at 120 ℃ for 30 s and wound at a speed of 500 m / min. This step utilizes the synergistic control of airflow and thermal draw to achieve the axial orientation of the conductive network in the fiber, thereby optimizing the photothermal conversion path and electron transport efficiency, ensuring that the fiber has a fast response and high stability, and improving compatibility through physical coating.

[0040] Example 3

[0041] S1. Preparation of quasi-spherical graphene quantum dots: Weigh 4 g of graphite powder and slowly add it to 220 mL of deionized water. Place the mixture on a magnetic stirrer and stir at 350 rpm for 18 min at room temperature to form a preliminary suspension. Transfer it to an ultrasonic cleaner with a power of 110 W, set the temperature to 28℃, and sonicate for 35 min to exfoliate the graphite into thin layers of graphene using weak shear force. Then, transfer the suspension to a variable power ultrasonic cell disruptor equipped with a 28℃ constant temperature device. Use gradient power mode, first sonicate at 350 W for 35 min, then at 450 W for 35 min, with pulse parameters set to 2.5 s working time and 3.5 s interval to precisely break the graphene sheets through cavitation effect. Afterward, quickly transfer the dispersion to a freeze dryer, set the temperature to -35℃, and freeze for 4.5 h. Utilize the template effect of ice crystals during freeze drying to prevent the graphene sheets from recombining and form a highly dispersed quasi-spherical structure. After freezing, centrifuge at 11000 rpm using a high-speed refrigerated centrifuge. Centrifuge at rpm for 18 min to remove agglomerates with a particle size greater than 20 nm and collect the supernatant; finally, screen 15-20 nm spherical graphene quantum dots through membrane filtration and collect them for later use; this step uses graded sonication and cryotemplation to precisely control the size and morphology of graphene quantum dots, obtain a highly uniform spherical structure, thereby enhancing the specific surface area and dispersibility of quantum dots, providing an ideal basic material for subsequent interfacial bonding, and avoiding agglomeration problems caused by irregular morphology.

[0042] S2. Preparation of grooved graphene-carbon nanotube hybrid material: Weigh 3.5 g of graphene sheet and 1.2 g of multi-walled carbon nanotubes, mix them, and place them in a low-temperature plasma treatment instrument. Evacuate to 7 × 10⁻⁶. -3 Argon gas was introduced at a flow rate of 11 L / min, maintaining a pressure of 55 Pa. The plasma power was set to 85 W, and the etching time to 11 min, using high-energy particle bombardment to form trench structures 100-200 nm wide. Then, the etched material and 0.06 g of bio-based wax dispersant were added to 160 mL of anhydrous ethanol and stirred to form a suspension. This suspension was transferred to a high-speed mill at 8500 rpm for 18 min to embed carbon nanotubes into the graphene trenches. The mixture was then sonicated at 420 W for 35 min using an ultrasonic cell disruptor to enhance dispersion. Finally, the mixture was filtered using a vacuum filtration device with a 0.22 μm pore size, and the filter cake was dried in a vacuum drying oven at 85 °C for 2.5 seconds. h, a grooved hybrid material is obtained; this step uses plasma etching to create micron-scale trenches on the graphene surface, and fixes carbon nanotubes in the trenches through mechanical intercalation to form a stable hybrid structure, thereby enhancing the interfacial bonding force and dispersion stability of the material, providing anchoring points for subsequent quantum dot embedding, and improving the mechanical strength of the overall conductive network.

[0043] S3. Construction of the interface-strengthening composite: Weigh 1.8 g of the spherical graphene quantum dots obtained in step S1 and 4.5 g of the grooved hybrid material obtained in step S2, and add them together to 170 mL of deionized water. First, place the mixture in a vortex mixer at 3200 rpm for 11 min to initially disperse it. Then, transfer it to an ultrasonic cleaner at 520 W for 22 min to ensure that the quantum dots are uniformly distributed in the grooves. Next, inject the mixture into a high-pressure homogenizer at 55 MPa and cycle it 5 times to embed the quantum dots into the grooves using high pressure, forming a tenon-and-mortise structure. Then, let it stand at 28℃ for 2.5 h to stabilize the interface through π-π stacking. Finally, centrifuge at 13000 rpm for 22 min, wash, and vacuum dry at 85℃ for 3.5 h to obtain the interface-strengthening composite. This step uses a closed-loop process of "size adaptation - initial dispersion - precise embedding - interface stabilization - purification and drying" to utilize the size complementarity of quantum dots, carbon nanotubes, and grooves, combined with physical intercalation and π-π stacking. The synergistic effect of stacking creates a robust "mortise and tenon" interface, significantly improving the interface shear strength and conductivity, thereby constructing a highly efficient three-dimensional conductive network and avoiding network breakage or performance degradation.

[0044] S4. Preparation of intelligent fiber spinning: Weigh 9 g of the composite obtained in step S3 and 0.45 g of silane coupling agent KH550, add them to a high-speed mixer, set the speed to 1550 rpm and the temperature to 85 ℃, pre-treat for 5.5 min to coat the coupling agent; then add 170 g of polyamide 6 chips and 9.5 g of thermoplastic polyurethane, adjust the speed to 2050 rpm and the temperature to 92 ℃, mix for 11 min; then add the mixture to a twin-screw extruder, set the feed section temperature to 225 ℃, the melt section temperature to 255 ℃, the die head section temperature to 265 ℃, and the screw speed to 310 rpm, after melt blending, extrude and granulate to obtain a composite masterbatch with a diameter of 2.8 mm; add the masterbatch to a vertical melt spinning machine, control the spinning temperature to 245 ℃, introduce 275 ℃ nitrogen gas at a flow rate of 9 m / s, and coordinate with a drafting roller speed of 420 The spun fibers are oriented and arranged by rpm and a thermal draw ratio of 3.2:1. The fibers are then heat-set at 125 ℃ for 35 s and wound at a speed of 520 m / min. This step utilizes the synergistic control of airflow and thermal draw to achieve axial orientation of the conductive network in the fiber, thereby optimizing the photothermal conversion path and electron transport efficiency, ensuring that the fiber has a fast response and high stability, and improving compatibility through physical coating.

[0045] Example 4

[0046] S1. Preparation of spherical graphene quantum dots: Weigh 5 g of graphite powder and slowly add it to 250 mL of deionized water. Place the mixture on a magnetic stirrer and stir at 400 rpm for 20 min at room temperature to form a preliminary suspension. Transfer it to a 120 W ultrasonic cleaner, set the temperature to 30℃, and sonicate for 40 min to exfoliate the graphite into thin layers of graphene using weak shear force. Then, transfer the suspension to a variable power ultrasonic cell disruptor equipped with a 30℃ constant temperature device. Use gradient power mode, first sonicate at 400 W for 40 min, then at 500 W for 40 min, with pulse parameters set to 3 s working and 4 s intermittent to precisely break the graphene sheets through cavitation effect. Afterward, quickly transfer the dispersion to a freeze dryer, set the temperature to -30℃, and freeze for 5 h. Utilize the template effect of ice crystals during freeze drying to prevent the graphene sheets from recombining and form a highly dispersed spherical structure. After freezing, centrifuge at 12000 rpm for 20 minutes using a high-speed refrigerated centrifuge. The process involves removing agglomerates larger than 20 nm and collecting the supernatant. Finally, 15-20 nm spherical graphene quantum dots are screened out by membrane filtration and collected for later use. This step uses graded ultrasonication and a frozen template method to precisely control the size and morphology of graphene quantum dots, obtaining a highly uniform spherical structure, thereby enhancing the specific surface area and dispersibility of the quantum dots, providing an ideal base material for subsequent interfacial bonding, and avoiding agglomeration problems caused by irregular morphology.

[0047] S2. Preparation of grooved graphene-carbon nanotube hybrid material: Weigh 4 g of graphene sheet and 1.5 g of multi-walled carbon nanotube, mix them, and place them in a low-temperature plasma treatment instrument. Evacuate to 10 °C. -2 Argon gas was introduced at a flow rate of 12 L / min, maintaining a pressure of 60 Pa. The plasma power was set to 90 W, and the etching time to 12 min, using high-energy particle bombardment to form trench structures 100-200 nm wide. Then, the etching material and 0.07 g of bio-based wax dispersant were added to 180 mL of anhydrous ethanol and stirred to form a suspension. This suspension was then transferred to a high-speed mill at 9000 rpm for 20 min to embed carbon nanotubes into the graphene trenches. The mixture was then sonicated at 450 W for 40 min using an ultrasonic cell disruptor to enhance dispersion. Finally, a vacuum filtration device with a 0.22 μm pore size was used for filtration, and the filter cake was dried in a vacuum drying oven at 90 °C for 3 minutes. h, a grooved hybrid material is obtained; this step uses plasma etching to create micron-scale trenches on the graphene surface, and fixes carbon nanotubes in the trenches through mechanical intercalation to form a stable hybrid structure, thereby enhancing the interfacial bonding force and dispersion stability of the material, providing anchoring points for subsequent quantum dot embedding, and improving the mechanical strength of the overall conductive network.

[0048] S3. Construction of the interface-strengthening composite: Weigh 2 g of the spherical graphene quantum dots obtained in step S1 and 5 g of the grooved hybrid material obtained in step S2, and add them together to 180 mL of deionized water. First, place the mixture in a vortex mixer at 3500 rpm for 12 min to initially disperse it. Then, transfer it to an ultrasonic cleaner at 550 W for 25 min to ensure that the quantum dots are uniformly distributed in the grooves. Next, inject the mixture into a high-pressure homogenizer at 60 MPa and cycle it 6 times to embed the quantum dots into the grooves using high pressure, forming a tenon-and-mortise structure. Then, let it stand at 30℃ for 3 h to stabilize the interface through π-π stacking. Finally, centrifuge at 14000 rpm for 25 min, wash, and vacuum dry at 90℃ for 4 h to obtain the interface-strengthening composite. This step uses a closed-loop process of "size adaptation - initial dispersion - precise embedding - interface stabilization - purification and drying" to utilize the size complementarity of quantum dots, carbon nanotubes, and grooves, combined with physical intercalation and π-π stacking. The synergistic effect of stacking creates a robust "mortise and tenon" interface, significantly improving the interface shear strength and conductivity, thereby constructing a highly efficient three-dimensional conductive network and avoiding network breakage or performance degradation.

[0049] S4. Preparation of Smart Fiber Spinning: Weigh 10 g of the composite obtained in step S3 and 0.5 g of silane coupling agent KH550, add them to a high-speed mixer, set the speed to 1600 rpm and the temperature to 90 ℃, pre-treat for 6 min to coat the coupling agent; then add 180 g of polyamide 6 chips and 10 g of thermoplastic polyurethane, adjust the speed to 2100 rpm and the temperature to 95 ℃, mix for 12 min; then add the mixture to a twin-screw extruder, set the feed section temperature to 230 ℃, the melt section temperature to 260 ℃, the die head section temperature to 270 ℃, and the screw speed to 320 rpm, after melt blending, extrude and granulate to obtain a composite masterbatch with a diameter of 3 mm; add the masterbatch to a vertical melt spinning machine, control the spinning temperature to 250 ℃, introduce 280 ℃ nitrogen gas at a flow rate of 10 m / s, and coordinate with a drafting roller speed of 450 rpm. The spun fibers are oriented and arranged by rpm and a thermal draw ratio of 3.5:1. The fibers are then heat-set at 130 ℃ for 40 s and wound at a speed of 550 m / min. This step utilizes the synergistic control of airflow and thermal draw to achieve the axial orientation of the conductive network in the fiber, thereby optimizing the photothermal conversion path and electron transport efficiency, ensuring that the fiber has a fast response and high stability, and improving compatibility through physical coating.

[0050] Comparative Example 1: Except for step S1, in which an equal amount of graphite powder is weighed, added to a ball mill and ball-milled at 500 rpm for 2 hours, and the product is collected directly, all other steps are the same as in Example 1.

[0051] Comparative Example 2: Except for omitting the gradient sonication step in step S1, and directly using an ultrasonic cell disruptor to continuously sonicate the graphite powder suspension at 250 W power for 40 min, the other steps are the same as in Example 1.

[0052] Comparative Example 3: Except for step S1, after ultrasonic treatment, the freeze-drying was not performed, but the product was directly evaporated at room temperature and then centrifuged for separation. All other steps were the same as in Example 1.

[0053] Comparative Example 4: Except for step S2, which omits the plasma etching step and directly mixes the graphene sheet and carbon nanotubes before mechanical grinding and dispersion, all other steps are the same as in Example 1.

[0054] Comparative Example 5: Except for step S2, after etching is completed, no high-speed grinding is performed, and the subsequent dispersion step only uses ultrasonic dispersion for 30 minutes, the other steps are the same as in Example 1.

[0055] Comparative Example 6: Except for step S2, in addition to adding the bio-based wax dispersant, 0.05g of silane coupling agent KH550 was added for chemical modification (stirred at room temperature for 1h) to replace the interface strengthening effect of physical etching, the other steps were the same as in Example 1.

[0056] Comparative Example 7: Except for step S3, which omits the high-pressure homogenization step and mixes the quantum dots and hybrid materials only by magnetic stirring (500 rpm, 1 h), the other steps are the same as in Example 1.

[0057] Comparative Example 8: Except for step S3, which involves high-pressure homogenization followed by direct centrifugation and drying without allowing the mixture to stand, all other steps are the same as in Example 1.

[0058] Comparative Example 9: Except for step S3, which uses ordinary graphene sheets (particle size 50-100nm) and carbon nanotubes for simple mechanical mixing (high-speed grinding for 10 minutes) and the same raw material ratio as in Example 1 (graphene: carbon nanotubes = 4:1, w / w), without quantum dot and trench structure construction, all other steps are the same as in Example 1.

[0059] Comparative Example 10: Except for step S4, which omits the airflow guiding step and does not introduce nitrogen during spinning, relying solely on the stretching roller for tension, all other steps are the same as in Example 1.

[0060] Comparative Example 11: Except for step S4, where the spinning is not processed by heat setting rollers and the yarn is directly wound, all other steps are the same as in Example 1.

[0061] Comparative Example 12: Except for step S4, in which ordinary graphene (purchased from Beijing Boyu High-Tech Materials Co., Ltd., particle size 50-100 nm, purity ≥99%) is directly blended with the polymer and spun, without going through steps S1-S3 to construct the mortise and tenon structure, all other steps are the same as in Example 1.

[0062] The test samples in this section are the spherical graphene quantum dots obtained in step S1 of Examples 1-4 and Comparative Examples 1-3.

[0063] 1.1 Specific surface area test The analysis was performed using a Micromeritics ASAP2460 analyzer and the nitrogen adsorption method (BET method). After the sample was degassed under vacuum at 120℃ for 6 h, it was cooled to -196℃ to measure the adsorption-desorption isotherms and calculate the specific surface area.

[0064] 1.2 Hardness Test The sample was pressed into a thin film using a TI-950 nanoindenter (Berkovich indenter) (pressure 10 MPa), and loaded at a rate of 5 mN / s to an indentation depth of 100 nm. The hardness was calculated using the Oliver-Pharr method.

[0065]

[0066] Figure 1-4 SEM images of the spherical graphene quantum dots prepared in Example 1 and Comparative Examples 1-3 of this invention are shown below. Table 1 presents the performance comparison results of the spherical graphene quantum dots. The quantum dots prepared in Examples 1-4 by the graded ultrasonic-freeze template method have significantly higher specific surface area and hardness than those in the comparative examples. This indicates that gradient power ultrasonication effectively controls the fracture of graphene sheets, while the ice crystal template during freeze-drying guides the self-assembly of the spherical structure, thereby obtaining quantum dots with high specific surface area and excellent mechanical stability. In contrast, Comparative Example 1 has irregular morphology and is prone to agglomeration, resulting in the worst performance; Comparative Examples 2 and 3 also have significantly worse performance than the examples due to inaccurate size control and lack of morphology guidance, respectively. This result fully demonstrates the necessity and synergistic effect of the process combination in step S1 of this invention.

[0067] The test samples in this section are the grooved graphene-carbon nanotube hybrid materials obtained in step S2 of Example 1 and Comparative Examples 4-6.

[0068] 2.2 Interfacial Shear Strength The hybrid material was mixed with epoxy resin (1:1 by mass) and applied as an adhesive between two rigid metal specimens to form a 10 mm × 10 mm overlap area. The adhesive layer thickness was controlled at 0.1 mm, and the mixture was cured at room temperature for 24 h. The specimens were then stretched at a rate of 1 mm / min until fracture, and the maximum shear force F was recorded. max Calculate shear strength: Strength (MPa) = F max (N) / 100 mm 2(Note: 100 mm² is the overlap area, i.e. the shear stress surface).

[0069] 2.3 Conductivity The sample was pressed into a thin film with a diameter of 20 mm and a thickness of 1 mm (pressure 10 MPa). The conductivity (S / cm) was measured using a four-probe resistance meter (model: ST2258C).

[0070] Sample preparation steps: Accurately weigh 0.5 g of sample. Using a powder press, press the sample into a uniform, dense, circular film with a diameter of 20 mm and a thickness of 1.0 ± 0.1 mm for 2 minutes.

[0071] Measurement Procedure: Use a four-probe resistance meter (ST2258C). Make uniform and flat contact between the four probes and the sample film surface. Apply a constant, minute current to the two outer probes and measure the voltage drop between the two inner probes. Calculate the volume resistivity (ρ): ρ = (π × S × V) / I, where S is the distance between the four probes in centimeters (cm), V is the voltage drop measured between the two inner probes in volts (V), and I is the constant current injected into the two outer probes in amperes (A). Conductivity (σ) is the reciprocal of resistivity (σ = 1 / ρ), with units of S / cm.

[0072]

[0073] Table 2 shows the comparison results of the interfacial properties of the grooved hybrid materials. The test results indicate that the hybrid material of Example 1 possesses a regular groove structure, the highest interfacial shear strength, and the highest electrical conductivity. This is attributed to the effective anchoring points created by plasma etching and the strong mechanical interlocking of carbon nanotubes achieved by high-speed grinding, forming a continuous three-dimensional conductive pathway. Comparative Example 4, lacking a groove structure, exhibits poor interfacial bonding and the lowest performance. Comparative Example 5, although possessing some grooves, fails to effectively embed carbon nanotubes, resulting in a significant decrease in interfacial and conductive properties. Comparative Example 6, while having acceptable interfacial strength, may introduce an insulating layer, leading to lower electrical conductivity compared to Example 1. This demonstrates the advantages of the all-physical method in step S2 of this invention.

[0074] III. Construction of Mortise and Tenon Structure Composite and Verification of Conductive Network Performance The test samples in this section are the interface-strengthening composites obtained in step S3 of Example 1 and Comparative Examples 7-9.

[0075] 3.1 Electrical conductivity The sample was pressed into a thin film with a diameter of 20 mm and a thickness of 1 mm (pressure 10 MPa). The conductivity (S / cm) was measured using a four-probe resistance meter (model: ST2258C).

[0076] Sample preparation steps: Accurately weigh 0.5 g of sample. Using a powder press, press the sample into a uniform, dense, circular film with a diameter of 20 mm and a thickness of 1.0 ± 0.1 mm under a pressure of 10 MPa for 2 min.

[0077] Measurement Procedure: Use a four-probe resistance meter (ST2258C). Make uniform and flat contact between the four probes and the sample film surface. Apply a constant, minute current to the two outer probes and measure the voltage drop between the two inner probes. Calculate the volume resistivity (ρ): ρ = (π × S × V) / I, where S is the distance between the four probes in centimeters (cm), V is the voltage drop measured between the two inner probes in volts (V), and I is the constant current injected into the two outer probes in amperes (A). Conductivity (σ) is the reciprocal of resistivity (σ = 1 / ρ), with units of S / cm.

[0078] 3.2 Interface Mechanical Stability Test Load-displacement curves were recorded using a TI-950 nanoindenter (Berkovich indenter) at a depth of 100 nm with a loading rate of 5 mN / s. The contact area A was calculated using the Oliver-Pharr method. The interfacial mechanical stability index was calculated using the formula: S = W unloading / A, where W unloading A is the unloading work (mJ) during the indentation process, and A is the indentation contact area (m²). 2 (Unit: mJ / m) 2 .

[0079]

[0080] Figure 5 This is a SEM image of the interface-reinforced composite prepared in Example 1 of the present invention. Figure 5As can be seen from the table, graphene quantum dots were embedded in the trenches, successfully preparing a mortise and tenon structure composite. Table 3 shows the comparison results of the conductivity of the mortise and tenon structure composites. As can be seen from Table 3, the composite of Example 1 exhibits the best overall performance. Its highest electrical conductivity, thermal conductivity, and interfacial mechanical stability index are due to the stabilizing effect of the high-pressure homogeneous driven quantum dot "mortise and tenon" embedding and π-π stacking—quantum dots fill the gaps in the trenches, forming a continuous conductive network with carbon nanotubes, significantly reducing electron transport resistance. Comparative Example 7 only involved physical mixing, and the quantum dots were not effectively embedded in the trenches, resulting in weak interfacial bonding and broken conductive pathways. Therefore, it had the lowest electrical conductivity and stability index. Comparative Example 8 lacked the π-π stacking stabilization process, and the quantum dots easily slipped from the trenches. The interfacial mechanical stability index and electrical conductivity were significantly lower than those of Example 1. Comparative Example 9 did not construct the interlocking structure of quantum dots and trenches, relying only on the simple mixing of graphene and carbon nanotubes. The conductive network was discontinuous, and the performance was comprehensively degraded. This result highlights the crucial role of the synergistic effect of "high-pressure homogenization" and "π-π stacking" in step S3 in constructing a high-performance three-dimensional conductive network.

[0081] The test samples in this section are the conductive composite fibers obtained in step S4 of Examples 1 and Comparative Examples 10-12. The samples used for photothermal testing are woven 10.0 × 10.0 cm fibers. 2 Fabric; fiber samples used for tensile testing were 100.0 mm in length; samples used for animal experiments were cut into 1.0 × 1.0 cm pieces. 2 The fiber samples used for stability tests were directly obtained conductive composite fibers.

[0082] 4.1 Photothermal responsiveness The photothermal temperature rise performance of the fiber fabric was tested using an XR-3 photothermal performance tester (equipped with a 1000W xenon arc lamp light source, an infrared thermal imager, and an irradiance meter). The fiber samples were woven to a size of 10.0 × 10.0 cm. 2 The fabric was symmetrically fixed to the center of the sample stage using aluminum alloy clamps to ensure no wrinkles and uniform light exposure. The xenon lamp irradiance was calibrated to 400.0 ± 5.0 W / m² before testing. 2 Initial temperature T initial =23±1℃, and stability was monitored in real time using an irradiance meter. The infrared thermal imager was set to a resolution of 0.1℃ and continuously acquired the surface temperature distribution of the sample at a frequency of 1 Hz, covering the irradiated area and the edge area.

[0083] The test consisted of two phases: irradiation and cooling. The irradiation phase lasted 10 minutes, with the xenon lamp operating at a constant power, and dynamic temperature changes were recorded simultaneously to generate a temperature rise curve. The cooling phase involved monitoring for 10 minutes after the light source was turned off, analyzing the heat dissipation rate and residual heat characteristics. The formula for calculating the photothermal temperature rise ΔT is: ΔT = T max - Tinitial , among which, T max The highest temperature at the end of the irradiation period, T initial This is the initial temperature.

[0084] 4.2 Tensile strength test The fiber tensile strength was tested using an Instron 5967 universal testing machine. The equipment parameters were set as follows: clamp spacing 50.0 mm and tensile rate 10.0 mm / min. Fiber samples (the products obtained in step S4 of Examples 1 and Comparative Examples 10-12) were cut into 100.0 mm long segments and symmetrically clamped using the clamps to ensure no pre-tension interference. The force and displacement sensors of the testing machine were calibrated before testing.

[0085] After starting the testing machine, apply a constant load until the fiber breaks, and simultaneously record the load-displacement curve. The formula for calculating tensile strength is: σ (MPa) = F max (N) / S (mm 2 The cross-sectional area S is calculated by measuring the fiber diameter using a microscope (S = π × (d / 2)). 2 The diameter is the average of the maximum and minimum values ​​in the vertical direction of the fiber cross-section.

[0086] 4.3 Animal Experiments Healthy male Kunming mice (weighing 20.0 ± 0.5 g), six mice per group (sample numbers 1-6), were purchased from Nanjing Junke Biotechnology Co., Ltd. and housed in an SPF-grade environment (temperature 22.0℃, humidity 57%). Fiber samples were sterilized with ethylene oxide (54.0℃, humidity 65%, concentration 900 mg / L, for 6.0 h) and then cut into 1.0 × 1.0 cm pieces. 2 Prepared in sheet form. Mice were anesthetized by intraperitoneal injection of sodium pentobarbital (50.0 mg / kg), their backs were shaved and disinfected, and a 1.0 cm longitudinal incision was made along the midline. Subcutaneous tissue was bluntly dissected to a depth of 4 mm, and a fibrous sample was implanted. The incision was sutured layer by layer using 4-0 PDS absorbable sutures. Postoperatively, mice were housed individually to observe wound healing and their diet and activity levels. No antibiotics were used to prevent infection. Seven days later, mice were euthanized by cervical dislocation, and the implant and surrounding tissue (including a 0.5 cm margin of normal tissue) were harvested. The tissue was fixed in formalin for 24.0 h and then transferred to 70% ethanol for preservation.

[0087] Tissues were dehydrated in a gradient manner (1.0 h each in 70%, 80%, 90%, 95%, and 100% ethanol), cleared in xylene (2.0 h × 2 times), and infiltrated with paraffin (60.0℃, 2.0 h × 3 times), then embedded in paraffin blocks. Serial sections (5.0 μm thick) were mounted on APES-treated slides and baked at 60.0℃ for 2.0 h. H&E staining was performed (hematoxylin staining for 3.5 min → rinsing with running water → differentiation with 1% hydrochloric acid alcohol for 30 s → eosin staining for 1.5 min → gradient dehydration → clearing in xylene → mounting with neutral resin). Ten high-power fields (×200) were randomly selected from each slide. The inflammatory response was independently assessed using a modified Leica scoring system (0-5 points) in a double-blind manner. Scoring criteria: 0 points = no inflammatory cell infiltration; 1 point = scattered lymphocytes (≤5 / HPF); 2 points = inflammatory cell aggregation (6-20 / HPF) with mild edema; 3 points = dense inflammatory cells (>20 / HPF) with tissue necrosis; 4 points = suppurative inflammation; 5 points = extensive necrosis with fibrosis. The final score was the average of the two physicians' scores.

[0088] 4.4 Stability Test The fiber samples obtained in Example 1 and Comparative Examples 10-12 were placed in a constant temperature and humidity chamber and subjected to accelerated aging tests at 60°C and 90% relative humidity (RH). Samples were removed every 24 hours to test their photothermal temperature rise (ΔT) and volumetric conductivity, with continuous testing for 7 days (168 hours). The performance degradation rate was calculated using the formula: Degradation rate (%) = [(Initial value - Current value) / Initial value] × 100%.

[0089]

[0090]

[0091] Table 4 shows the comprehensive performance comparison results of the smart fibers. Table 5 shows the long-term stability test results of the smart fibers (168 hours, 60°C / 90% RH). Example 1 fiber showed the best performance in photothermal temperature rise, tensile strength, and biocompatibility, thanks to the axially oriented "mortise and tenon" conductive network that achieved efficient photothermal conversion and stress transfer. Comparative Example 10, by omitting airflow guidance, resulted in a disordered arrangement of the conductive network within the fiber, which not only reduced photothermal and conductive properties but also potentially increased physical irritation to surrounding tissues due to the uneven fiber surface morphology; therefore, its biocompatibility score was slightly higher than Example 1. Comparative Example 11 showed insufficient stability in its internal molecular chains and conductive network, resulting in performance inferior to Example 1. Comparative Example 12, due to the complete absence of a core conductive network structure, exhibited extremely low photothermal performance, which ironically demonstrates the necessity of the three-dimensional network constructed in this invention. Long-term stability tests (Table 5) further show that the performance degradation rate of Example 1 fiber is extremely low under harsh humid and hot conditions, demonstrating its excellent stability and meeting practical application requirements.

[0092] The fibers obtained by this invention are further processed and spun into fabric. The resulting fabric product image is shown below. Figure 8 and Figure 9 As shown.

[0093] The above-described embodiments are merely illustrative of specific implementations of the present invention, and while the descriptions are detailed, they should not be construed as limiting the scope of protection of the present invention. It should be noted that for those skilled in the art, any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention should be considered equivalent substitutions and are included within the scope of protection of the present invention.

Claims

1. A method for preparing conductive composite fibers based on graphene and graphene quantum dot bridging, characterized in that: Includes the following steps: S1. Spherical graphene quantum dots were prepared by a graded ultrasonic-cryogenic template method. S2. Grooved graphene-carbon nanotube hybrid materials were prepared by plasma etching-mechanical intercalation. S3. An interface-strengthened composite is constructed by physical intercalation-π stacking synergistic method, in which the spherical graphene quantum dots are embedded in the grooved hybrid material; S4. The interface-reinforcing composite is blended with the polymer matrix by airflow field-controlled spinning to prepare a smart fiber with an axially oriented conductive network.

2. The method for preparing a conductive composite fiber based on graphene and graphene quantum dot bridging according to claim 1, characterized in that: The specific preparation method of composite fibers is as follows: S1. Preparation of spherical graphene quantum dots: Weigh 1-5 g of graphite powder and slowly add it to 150-250 mL of deionized water. Place the mixture on a magnetic stirrer and stir at 200-400 rpm for 10-20 min at room temperature to form a preliminary suspension. Transfer the suspension to an ultrasonic cleaner with a power of 80-120 W, set the temperature to 20-30℃, and sonicate for 20-40 min. Then transfer the suspension to a variable power ultrasonic cell disruptor equipped with a 20-30℃ constant temperature device. Use gradient power mode, first sonicate at 200-400 W for 20-40 min, then sonicate at 300-500 W for 20-40 min, with pulse parameters set to 1-3 s for operation and 2-4 s for interval. Afterward, quickly transfer the dispersion to a freeze dryer, set the temperature to -50 to -30℃, and freeze for 3-5 h. After freezing, centrifuge at 8000-12000 rpm. Centrifuge at rpm for 10-20 min and collect the supernatant; finally, screen out 15-20 nm spherical graphene quantum dots through membrane filtration and collect them for later use. S2. Preparation of grooved graphene-carbon nanotube hybrid materials: Weigh 2-4 g of graphene sheets and 0.5-1.5 g of multi-walled carbon nanotubes, mix them, and place them in a low-temperature plasma treatment instrument, then evacuate to 10°C. -3 -10 -2 Argon gas was introduced at a flow rate of 8-12 L / min, maintaining a pressure of 40-60 Pa. The plasma power was set to 70-90 W, and the etching time to 8-12 min. High-energy particles were used to bombard the material to form a trench structure 100-200 nm wide. Then, the etched material and 0.03-0.07 g of bio-based wax dispersant were added to 120-180 mL of anhydrous ethanol and stirred to form a suspension. The suspension was then transferred to a high-speed mill at 7000-9000 rpm for 10-20 min to embed carbon nanotubes into the graphene trenches. The suspension was then sonicated at 350-450 W for 20-40 min using an ultrasonic cell disruptor. Finally, the suspension was filtered using a vacuum filtration device with a pore size of 0.22 μm. The filter cake was dried in a vacuum drying oven at 70-90 °C for 1-3 h to obtain the trench-shaped hybrid material. S3. Construction of the interface-strengthening composite: Weigh 1-2 g of the spherical graphene quantum dots obtained in step S1 and 3-5 g of the grooved hybrid material obtained in step S2, and add them together to 120-180 mL of deionized water; first place the mixture in a vortex mixer at a speed of 2500-3500 rpm for 8-12 min; then transfer it to an ultrasonic cleaner at a power of 450-550 W for 15-25 min; then inject the mixture into a high-pressure homogenizer at a pressure of 40-60 MPa and cycle it 4-6 times; then let it stand at 20-30℃ for 1-3 h; finally, centrifuge at 10000-14000 rpm for 15-25 min, wash, and vacuum dry at 70-90℃ for 2-4 h to obtain the interface-strengthening composite; S4. Spinning preparation of smart fibers: Weigh 6-10 g of the composite obtained in step S3 and 0.3-0.5 g of silane coupling agent KH550, add them to a high-speed mixer, set the speed to 1400-1600 rpm and the temperature to 70-90 ℃, and pre-treat for 4-6 min; then add 120-180 g of polyamide 6 chips and 8-10 g of thermoplastic polyurethane, adjust the speed to 1900-2100 rpm and the temperature to 85-95 ℃, and mix for 8-12 min; then add the mixture to a twin-screw extruder, set the feed section temperature to 210-230 ℃, the melt section temperature to 240-260 ℃, the die head section temperature to 250-270 ℃, and the screw speed to 280-320 rpm, melt blend and then extrude and granulate to obtain a diameter of 2-3 mm. The composite masterbatch is prepared in mm. The masterbatch is added to a vertical melt spinning machine, the spinning temperature is controlled at 230-250℃, nitrogen gas at 260-280℃ is introduced, the flow rate is 6-10 m / s, the speed of the drawing roller is 350-450 rpm, and the hot draw ratio is 2.5:1-3.5:

1. The spun fibers are treated by a heat setting roller at 110-130℃ for 20-40 s, and the winding machine speed is controlled at 450-550 m / min for winding and forming.

3. The method for preparing a conductive composite fiber based on graphene and graphene quantum dot bridging according to claim 2, characterized in that: In step S1, 1 g of graphite powder was weighed and slowly added to 150 mL of deionized water. The mixture was placed on a magnetic stirrer and stirred at 200 rpm for 10 min at room temperature to form a preliminary suspension. The suspension was then transferred to an 80 W ultrasonic cleaner, set to 20°C, and sonicated for 20 min. The suspension was then transferred to a variable power ultrasonic cell disruptor equipped with a 20°C constant temperature device. Gradient power mode was used, first sonicating at 200 W for 20 min, then at 300 W for 20 min, with pulse parameters set to 1 s on and 2 s off. The dispersion was then quickly transferred to a freeze dryer, set to -50°C, and frozen for 3 h. After freezing, the mixture was centrifuged at 8000 rpm for 10 min using a high-speed refrigerated centrifuge and the supernatant was collected. Finally, 15-20 nm spherical graphene quantum dots were screened through membrane filtration and collected for later use.

4. The method for preparing a conductive composite fiber based on graphene and graphene quantum dot bridging according to claim 2, characterized in that: In step S2, 2 g of graphene sheets and 0.5 g of multi-walled carbon nanotubes are weighed, mixed, and placed in a low-temperature plasma treatment instrument, which is then evacuated to 10 °C. -3 Argon gas was introduced at a flow rate of 8 L / min, maintaining a pressure of 40 Pa. The plasma power was set to 70 W, and the etching time was 8 min. High-energy particles bombarded the material to form a trench structure with a width of 100-200 nm. Then, the etching material and 0.03 g of bio-based wax dispersant were added to 120 mL of anhydrous ethanol and stirred to form a suspension. The suspension was transferred to a high-speed mill and processed at 7000 rpm for 10 min. The suspension was then sonicated at 350 W for 20 min using an ultrasonic cell disruptor. Finally, the suspension was filtered using a vacuum filtration device with a filter membrane pore size of 0.22 μm. The filter cake was dried in a vacuum drying oven at 70 °C for 1 h to obtain the trench-shaped hybrid material.

5. The method for preparing a conductive composite fiber based on graphene and graphene quantum dot bridging according to claim 2, characterized in that: In step S2, 3 g of graphene sheets and 1.0 g of multi-walled carbon nanotubes are weighed, mixed, and placed in a low-temperature plasma treatment instrument, which is then evacuated to a vacuum of 5 × 10⁻⁶. -3 Argon gas was introduced at a flow rate of 10 L / min, maintaining a pressure of 50 Pa. The plasma power was set to 80 W, and the etching time was 10 min. High-energy particles were used to bombard the material to form a trench structure with a width of 100-200 nm. Then, the etching material and 0.05 g of bio-based wax dispersant were added to 150 mL of anhydrous ethanol and stirred to form a suspension. The suspension was transferred to a high-speed mill and processed at 8000 rpm for 15 min. The suspension was then sonicated at 400 W for 30 min using an ultrasonic cell disruptor. Finally, the suspension was filtered using a vacuum filtration device with a filter membrane pore size of 0.22 μm. The filter cake was dried in a vacuum drying oven at 80 °C for 2 h to obtain the trench-shaped hybrid material.

6. The method for preparing a conductive composite fiber based on graphene and graphene quantum dot bridging according to claim 2, characterized in that: In step S3, 1.5 g of the spherical graphene quantum dots obtained in step S1 and 4 g of the grooved hybrid material obtained in step S2 were weighed and added together to 150 mL of deionized water. The mixture was first placed in a vortex mixer at 3000 rpm for 10 min. Then it was transferred to an ultrasonic cleaner at 500 W for 20 min. The mixture was then injected into a high-pressure homogenizer at 50 MPa and cyclically processed 5 times. The high pressure was used to embed the quantum dots into the grooves to form a tenon-and-mortise structure. The mixture was then allowed to stand at 25 °C for 2 h. Finally, it was centrifuged at 12000 rpm for 20 min, washed, and then vacuum dried at 80 °C for 3 h to obtain the interface-reinforced composite.

7. The method for preparing a conductive composite fiber based on graphene and graphene quantum dot bridging according to claim 2, characterized in that: In step S3, 1 g of the spherical graphene quantum dots obtained in step S1 and 3 g of the grooved hybrid material obtained in step S2 are weighed and added to 120 mL of deionized water. The mixture is first placed in a vortex mixer at 2500 rpm for 8 min. Then it is transferred to an ultrasonic cleaner at 450 W for 15 min. The mixture is then injected into a high-pressure homogenizer at 40 MPa and cyclically processed 4 times. The high pressure is used to embed the quantum dots into the grooves to form a tenon-and-mortise structure. The mixture is then allowed to stand at 20 °C for 1 h. Finally, it is centrifuged at 10000 rpm for 15 min, washed, and then vacuum dried at 70 °C for 2 h to obtain the interface-reinforced composite.

8. The method for preparing a conductive composite fiber based on graphene and graphene quantum dot bridging according to claim 2, characterized in that: In step S4, 6 g of the composite obtained in step S3 and 0.3 g of silane coupling agent KH550 are weighed and added to a high-speed mixer. The speed is set to 1400 rpm and the temperature is controlled at 70 ℃. Pretreatment is performed for 4 min. Then, 120 g of polyamide 6 chips and 8 g of thermoplastic polyurethane are added. The speed is adjusted to 1900 rpm and the temperature to 85 ℃. Mixing is performed for 8 min. The mixture is then added to a twin-screw extruder. The feed section temperature is set to 220 ℃, the melt section temperature to 250 ℃, and the die head section temperature to 260 ℃. The screw speed is 280 rpm. After melt blending, the mixture is extruded and granulated to obtain a composite masterbatch with a diameter of 2 mm. The masterbatch is added to a vertical melt spinning machine. The spinning temperature is controlled at 240 ℃, and nitrogen gas at 280 ℃ is introduced at a flow rate of 6 m / s. The drafting roller speed is 350 rpm and the hot draw ratio is 2.5:

1. The spun fibers are treated with a 110 ℃ heat setting roller for 20 minutes. The winding machine speed is controlled at 450 m / min for winding and forming.

9. The conductive composite fiber based on graphene and graphene quantum dot bridging prepared according to any one of claims 1-8.

Images