Preparation method of photo-thermal driven liquid metal microsphere-polymer shape memory fiber and infrared anti-counterfeiting application of photo-thermal driven liquid metal microsphere-polymer shape memory fiber

Abstract

The invention discloses a preparation method of photo-thermal driven liquid metal microsphere-polymer shape memory fibers, which comprises the following steps: compounding liquid metal microspheres LMP with waterborne polyurethane WPU to form coating slurry with photo-thermal response capability, uniformly coating the surface of thermoplastic polyurethane / polycaprolactone TPU / PCL shape memory fibers prepared by a wet spinning process with the coating slurry, and carrying out photo-thermal driving on the surface of the TPU / PCL shape memory fibers to obtain the photo-thermal driven liquid metal microsphere-polymer shape memory fibers. And the TPU-PCL / LMP-WPU composite fiber with the photo-thermal response capability is obtained. The method has the advantages that illumination or near-infrared laser is applied to serve as an activation source, non-contact heating is achieved, and fiber deformation can be driven within a short time to complete anti-fake recognition.

Description

Technical Field

[0001] The present invention relates to the field of fiber and fabric materials, and in particular to the preparation of a photothermal driven liquid metal microsphere-polymer shape memory fiber and its infrared anti-counterfeiting application. Background Art

[0002] Fiber and fabric materials are widely used in clothing, home furnishings, and medical applications. However, their lack of intelligence has led to frequent counterfeiting of high-end fabrics, severely damaging the rights and interests of consumers and businesses. The development of intelligent fabric anti-counterfeiting technology is urgently needed. Currently, fabric anti-counterfeiting relies on physical tags (such as RFID and QR codes), chemical dyes (fluorescent / invisible ink), or structural designs (woven patterns and microstructured textures). These methods suffer from easy duplication, poor environmental stability, complex processes, and high recognition barriers. Furthermore, anti-counterfeiting tags are often in the form of thin films, making them incompatible with the intelligent, reliable, and personalized anti-counterfeiting requirements of flexible and breathable textiles. Compared to thin films, fiber-based smart wearable devices offer advantages such as softness, breathability, good conformability, and comfort. They also have good weavability and are easily integrated into textile processes. Shape memory polymers (SMPs) can return to their original shape after deformation through appropriate stimulation. Forming SMPs into fibers or fabrics is a breakthrough in intelligent fabric anti-counterfeiting technology. Currently, the triggering mechanism for SMPs is primarily thermal. However, while research on shape memory polymers focuses on developing novel polymer materials to enhance their thermomechanical properties and resilience, these materials still rely on electrical or direct heating for triggering, which poses numerous safety risks and inconveniences when worn. Furthermore, shape memory polymers currently primarily consist of thin films, unable to be organically integrated with fibers or fabrics, significantly limiting their application.

[0003] Document CN113174755A reports an elastic fiber containing an ionic liquid and a phase-change material. Leveraging the high conductivity of the ionic liquid, an electric current drives the phase change of the fiber's internal material, causing it to expand or contract. However, this method relies on heating with a wired power supply and does not involve triggering the shape memory function.

[0004] Existing literature uses contactless light-triggered materials. Document CN110725024A loads traditional semiconductor photothermal materials onto the surface of fibers prepared by wet spinning to construct photothermal responsive fiber materials. Document CN113512881A treats yarn in a polymer solution containing zirconium carbide by ultrasonic impregnation to obtain photothermal properties. Documents CN109851899A and WO2010045890A1 respectively propose mixing carbon materials such as carbon nanotubes and graphene with shape memory composites to prepare infrared light-responsive shape memory polymer films. Document CN105153864A uses ultraviolet light to trigger the shape memory effect of the film. Document CN116590915B constructs a photoinduced thermal conductive and energy storage fiber composed of elastic polyurethane fibers, thermal conductive composite phase change materials and elastic coatings, and introduces a porous structure by freeze-drying to significantly improve thermal conductivity. However, none of these methods have been able to achieve efficient, wavelength-controlled photothermal conversion based on fiber materials to trigger the shape memory effect for infrared anti-counterfeiting purposes. Furthermore, the limited photothermal conversion efficiency of traditional semiconductor or carbon materials, as well as the morphology of their composite films, make it difficult to effectively integrate them with fabrics, limiting their application in wearable textiles.

[0005] In recent years, gallium-indium liquid metal has attracted widespread attention. This material has excellent conductivity and fluidity and can generate heat when electricity is applied. Document CN110244396A is aimed at military scenarios and realizes a flexible infrared shielding camouflage film based on liquid metal and a temperature control system, which can be used for military infrared protection camouflage. Document CN118422371A prepared a thermoplastic polyurethane elastomer-liquid metal composite ink by ultrasonic mixing, and then combined it with 3D printing technology to prepare composite fibers. It exhibits excellent Joule heating effect under electric field and can be used for clothing warmth. Document CN115652624A uses the "drip coating-compression-PU curing" process to prepare a liquid metal-polyurethane composite highly conductive fabric with excellent electromagnetic shielding performance, which can be used for high-voltage electrostatic protection. Document CN116831536A develops a highly sensitive sensor based on elastic fabric and conductive material. By constructing a slip interface and a self-healing layer, it achieves excellent strain response, mechanical durability and tensile properties. Document CN118087083A uses dual-channel microfluidic coaxial wet spinning to prepare a skin-core structure fiber, which has polyacrylonitrile as the skin layer, contains thermochromic pigments and luminescent materials, and gallium-indium liquid metal as the core layer. It achieves thermally triggered color change and ultraviolet luminescence through Joule heating.

[0006] As can be seen from the above, triggering the shape memory effect of fibers through the photothermal effect of liquid metal has not yet been achieved. However, the photothermal conversion coefficient of conventional liquid metal is extremely low, making it difficult to achieve infrared anti-counterfeiting of fibers through light-triggered shape memory to meet the anti-counterfeiting requirements of smart fabrics. Furthermore, fixing liquid metal to the surface of fibers for wearable applications also faces challenges. This is an area that needs to be improved in this application. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a preparation method of photothermally driven liquid metal microsphere-polymer shape memory fiber and its infrared anti-counterfeiting application, applying light or near-infrared laser as an activation source to achieve non-contact heating, which can drive the fiber deformation in a short time to complete anti-counterfeiting identification.

[0008] To solve the above technical problems, the present invention provides a method for preparing photothermally driven liquid metal microsphere-polymer shape memory fibers. Liquid metal microspheres LMP are compounded with waterborne polyurethane WPU to form a coating slurry with photothermal response capability. The coating is evenly applied to the surface of thermoplastic polyurethane / polycaprolactone (TPU / PCL) shape memory fibers prepared by a wet spinning process to obtain TPU-PCL / LMP-WPU composite fibers with photothermal response capability. Light or near-infrared laser is applied as an activation source to achieve non-contact heating, driving fiber deformation in a short time to complete anti-counterfeiting identification. The specific steps are as follows: S1: Preparation of LMP-WPU photosensitive materials; S11: 1 g of gallium-containing liquid metal was added to 250 mL of anhydrous ethanol and ultrasonically dispersed using a cell disruptor in an ice-water bath. The ultrasonic power was set to 50-70% and the ultrasonic time was set to 15-30 min to obtain a liquid metal microsphere LMP / ethanol mixture. S12: mixing liquid metal microspheres LMP and ethanol to prepare an LMP / ethanol mixture; centrifuging the mixture at a speed of 50–5000 rpm for 5 minutes; collecting the supernatant after centrifugation and drying it in a constant temperature drying oven at 60° C. to obtain liquid metal microsphere LMP powder; Among them: by adjusting the centrifugal speed, liquid metal microspheres with different particle size distributions were obtained, and the particle size distribution was 151.34±9.50 -323.14±22.20 nm; S13: Weigh 0.1 g of dried LMP powder, add it to 200 μL of 10-30 wt% aqueous polyurethane WPU solution, and stir thoroughly to prepare LMP-WPU photothermal responsive composite slurry; S2: Preparation of TPU-PCL memory fibers; S21: Weigh 1 g of thermoplastic polyurethane (TPU) and 1 g of polycaprolactone (PCL), add them to 10 mL of dimethylformamide (DMF), and heat and stir in a 60°C water bath until they are completely dissolved to prepare a spinning solution. S22: After the spinning solution is allowed to stand and degas, it is transferred to a 5 mL syringe and connected to a 19-22 G needle. Wet spinning is performed at a rate of 5-8 mL / h, and the coagulation bath is deionized water. During the spinning process, dimethylformamide (DMF) and deionized water are fully exchanged to form a fiber structure, and the resulting fiber is then naturally dried to remove surface moisture. S23: After the fiber is completely dry, the prefabricated LMP / WPU photothermal responsive composite slurry is evenly coated on the fiber surface by brushing, and then naturally dried again to finally obtain photothermally driven liquid metal microsphere-polymer shape memory TPU-PCL / LMP-WPU fiber.

[0009] In order to give the fiber the ability to selectively respond to infrared light of different wavelengths, liquid metal microspheres LMP of different particle sizes are selected to regulate and modify the fiber surface to achieve controllable spectral absorption characteristics, further expanding its application potential in scenarios such as infrared anti-counterfeiting.

[0010] The gallium-containing liquid metal is a gallium-indium alloy.

[0011] Liquid metal microspheres LMP, as a photothermal conversion material, have excellent light absorption capabilities. UV-Vis spectrum tests show that they have significant absorption characteristics in the 200-900 nm band.

[0012] On the other hand, the present invention provides a fabric comprising a photothermally driven liquid metal microsphere-polymer shape memory fiber prepared according to the preparation method of the photothermally driven liquid metal microsphere-polymer shape memory fiber.

[0013] In another aspect, the present invention provides a photothermally driven liquid metal microsphere-polymer shape memory fiber prepared according to the preparation method of the photothermally driven liquid metal microsphere-polymer shape memory fiber for use as an infrared anti-counterfeiting application.

[0014] The photothermally driven liquid metal microsphere-polymer shape memory fiber achieves anti-counterfeiting functionality for fabrics through photothermal actuation. The photothermally driven liquid metal microsphere-polymer shape memory fiber is embedded or sewn into fabric. Upon exposure to a light source with a specific wavelength (808 nm), the fiber deforms and is used for visual identification or authentication, demonstrating clear anti-counterfeiting application potential.

[0015] The LMP-WPU photosensitive material in step S1 is replaced with a material having photothermal conversion properties, wherein the material having photothermal conversion properties is a two-dimensional transition metal carbide / nitride MXenes or a carbon nanotube CNT. The specific steps are as follows: Q1: Preparation of photothermal conversion materials; Q11: Add 2 g of a material with photothermal conversion properties into 20 mL of 4.5-5 M HCl solution and dissolve it; Q12: Slowly add 2 g of Ti3AlC2 powder into the above mixed solution and o C and stir for 24-48 hours; Q 13: After the reaction is completed and cooled to room temperature, the resulting mixture is washed several times with deionized water and centrifuged at 5000 rpm for 5-10 min until the pH value of the supernatant is greater than 6; Q 14: The dispersion was ultrasonicated for 30 minutes, and the solution was centrifuged at 3500 rpm for 30 minutes to separate the supernatant, which is the desired photothermal conversion material; Q 2: Preparation of TPU-PCL memory fiber; Q21: Weigh 1 g of thermoplastic polyurethane (TPU) and 1 g of polycaprolactone (PCL), add them to 10 mL of dimethylformamide (DMF), heat and stir in a 60°C water bath until completely dissolved to prepare a spinning solution. Q22: After the spinning solution is allowed to stand and degas, it is transferred to a 5 mL syringe and connected to a 19-22G needle. Wet spinning is performed at a rate of 7 mL / h. The coagulation bath is deionized water. During the spinning process, dimethylformamide (DMF) and deionized water are fully exchanged to form a fiber structure, and the resulting fiber is then naturally dried to remove surface moisture. Q23: After the fiber is completely dry, the pre-made supernatant is evenly applied to the fiber surface by brushing, and then naturally dried again to finally obtain a composite fiber with photothermal response capability.

[0016] The beneficial effects of the present invention are: 1) By combining the LMP-WPU coating with wet-spun TPU / PCL fibers, the photothermal response is enhanced while maintaining the fiber's flexibility and weaving compatibility. This allows for direct sewing or embedding into fabrics, making it feasible for practical apparel applications. Using light or near-infrared lasers as activation sources enables contactless heating, avoiding damage to the fabric caused by traditional heat sources and improving the flexibility and safety of the system's response. 2) Liquid metal microspheres (LMPs) have excellent light absorption capabilities in the range of 200 to 900 nm, particularly at a wavelength of 808 nm, exhibiting excellent photothermal conversion efficiency and a significant temperature rise effect (12.1°C higher than at a wavelength of 635 nm). They can also drive fiber deformation within 5 seconds for anti-counterfeiting identification. 3) By pre-training the shape memory of TPU / PCL memory fibers, the fabric can achieve a dynamic / static dual anti-counterfeiting effect under the action of light and heat. It has the anti-counterfeiting ability of customizable information and trigger-activated display. The anti-counterfeiting form is unique and difficult to imitate. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings: Figure 1 This is a flow chart for preparing a memory fiber with photothermal effect according to a specific embodiment of the present invention; Figure 2 This is a schematic diagram of the principle of the photothermal memory fiber according to a specific embodiment of the present invention; Figure 3 Schematic diagram of the photothermal effect of the photothermal memory fiber under different powers according to an embodiment of the present invention; Figure 4 This is a static anti-counterfeiting effect diagram of the photothermal memory fiber according to an embodiment of the present invention; Figure 5 This is a dynamic anti-counterfeiting effect diagram of the photothermal memory fiber according to an embodiment of the present invention. DETAILED DESCRIPTION

[0018] The embodiments of the present invention are described in detail below with reference to the accompanying drawings. Specific embodiments

[0019] The present invention provides a method for preparing a photothermal driven liquid metal microsphere-polymer shape memory fiber, wherein a fiber matrix is ​​formed of TPU / PCL and a surface layer is coated with an LMP-WPU composite coating to obtain a photothermal driven liquid metal microsphere-polymer shape memory TPU-PCL / LMP-WPU fiber. The specific steps are as follows (eg Figure 1 shown): S1: Preparation of LMP-WPU photosensitive materials; S11: 1 g of gallium-indium alloy LM was added to 250 mL of anhydrous ethanol and ultrasonically dispersed using a cell disruptor in an ice-water bath. The ultrasonic power was set to 70% and the ultrasonic time was set to 30 min to obtain a liquid metal microsphere LMP / ethanol mixture. S12: Liquid metal microspheres (LMP) were mixed with ethanol to prepare an LMP / ethanol mixture. The mixture was then centrifuged at 50–5000 rpm for 5 minutes. By adjusting the centrifugal speed, liquid metal microspheres with different particle size distributions (151.34 ± 9.50 - 323.14 ± 22.20 nm) were obtained. After centrifugation, the supernatant was collected and dried in a 60°C constant temperature drying oven to obtain liquid metal microsphere LMP powder. S13: Weigh 0.1 g of dried LMP powder, add it to 200 μL of 10 wt% aqueous polyurethane (WPU) solution, and stir thoroughly to prepare an LMP-WPU photothermal responsive composite slurry; S2: Preparation of TPU-PCL memory fibers; S21: Weigh 1 g of thermoplastic polyurethane (TPU) and 1 g of polycaprolactone (PCL), add them to 10 mL of dimethylformamide (DMF), and heat and stir in a 60°C water bath until they are completely dissolved to prepare a spinning solution. S22: After the spinning solution was allowed to stand for degassing, it was transferred to a 5 mL syringe and connected to a 22 G needle. Wet spinning was performed at a rate of 7 mL / h, and the coagulation bath was deionized water. During the spinning process, dimethylformamide (DMF) and deionized water are fully exchanged to form a fiber structure, and the resulting fiber is then naturally dried to remove surface moisture. S23: After the fiber is completely dry, the prefabricated LMP / WPU photothermal responsive composite slurry is evenly coated on the fiber surface by brushing, and then naturally dried again to finally obtain photothermally driven liquid metal microsphere-polymer shape memory TPU-PCL / LMP-WPU fiber.

[0020] The liquid metal microsphere LMP powder as a photothermal conversion material has excellent light absorption capacity. UV-Vis spectrum test shows that it has significant absorption characteristics in the 200-900 nm band. In addition, the TPU-PCL fiber can remember the driving principle as follows Figure 2As shown, its shape memory properties are primarily derived from the differences in the thermodynamic properties of its two components, particularly the melting-point-driven behavior of PCL. In this system, PCL serves as the "temporary shape" fixing phase with a relatively low melting point (approximately 60°C), while TPU serves as the "permanent shape" supporting phase, providing an elastic network structure. When the fiber is heated above the PCL melting point, the PCL segments are in a soft or molten state, and the fiber is shaped. Subsequently, cooling to room temperature causes the PCL to crystallize and fix the temporary shape. Upon further heating to above the PCL melting point, the PCL crystals melt, and the elastic TPU segments drive the fiber back to its original shape, achieving shape recovery. Therefore, this composite fiber exhibits typical thermally triggered shape memory behavior.

[0021] In laser excitation tests, liquid metal microspheres (LMP) achieved effective temperature increase under two different wavelengths (635 nm and 808 nm) of laser irradiation. The temperature increase effect at 808 nm was significantly higher by 12.1°C than that at 635 nm. Further tests showed that the photothermal response intensity of LMP and its composite fiber was positively correlated with the irradiation light power density. Figure 3 shown.

[0022] Due to the excellent photothermal properties of the prepared fibers, they are woven into specific patterns and blended with ordinary fabrics. When the fabric is irradiated with near-infrared light, only the TPU-PCL / LMP-WPU fibers significantly heat up due to the photothermal effect, thus forming a clear contrast with other fibers under the infrared thermal imager, realizing static anti-counterfeiting identification under infrared thermal imaging, such as Figure 4 As shown. In addition, the fiber also has good shape memory properties, which can be used to construct dynamic anti-counterfeiting functions. For example, the prepared photothermal driven liquid metal microsphere-polymer shape memory TPU-PCL / LMP-WPU fiber is placed in a molding mold prepared in advance by 3D printing, and heated under irradiation conditions of 808 nm laser power density of 0.85 W / cm², so that the fiber obtains the target temporary shape under the action of external force; then, while maintaining the deformation state, it is cooled to below the PCL crystallization temperature, so that the PCL phase is re-crystallized and the temporary shape is fixed. Through the above-mentioned thermodynamic treatment process, the shape memory properties of TPU / PCL fibers are pre-trained, so that they have reversible shape recovery capabilities under external thermal stimulation in subsequent applications. When the same power laser is applied again, the fiber temperature rises rapidly to the deformation drive threshold. Laser irradiation triggers the fiber to quickly recover to the preset morphology within 5 seconds, showing the preset graphics, anti-counterfeiting marks or identification information (such as Figure 5 As shown in the figure), a visual and responsive dynamic anti-counterfeiting recognition effect is achieved.

[0023] The present invention also provides a fabric, comprising a photothermally driven liquid metal microsphere-polymer shape memory fiber prepared according to the preparation method of the photothermally driven liquid metal microsphere-polymer shape memory fiber.

[0024] The present invention further provides a photothermally driven liquid metal microsphere-polymer shape memory fiber, prepared according to a method for preparing photothermally driven liquid metal microsphere-polymer shape memory fiber, for infrared anti-counterfeiting applications. By applying a certain amount of light to the fiber, a significant temperature rise is achieved through the photothermal conversion material on the fiber surface, thereby thermally triggering the fiber's shape memory function to achieve deformation. This provides a high degree of comfort while addressing the difficulties of traditional heating methods, thereby achieving a dual-function anti-counterfeiting technology with both static and dynamic properties. The present invention's intelligent fiber, which combines photothermal effects with shape memory functions, provides insights into intelligent fabric anti-counterfeiting technology and holds significant promise.

[0025] Photothermally driven liquid metal microspheres-polymer shape memory TPU-PCL / LMP-WPU fibers are sewn into the fabric to form an anti-counterfeiting device with a preset initial configuration. Specific embodiments

[0026] The LMP-WPU photosensitive material is replaced with a material with photothermal conversion properties. Taking MXene as an example, the present invention combines the photothermal conversion material with shape memory polymer fibers to produce photothermally triggered smart fibers. The specific steps are as follows: Q1: Preparation of photothermal conversion materials; Q11: Add 2 g of LiF to 20 mL of 4.5 M HCl solution and dissolve; Q12: Slowly add 2 g of Ti3AlC2 powder into the above mixed solution and o C and stirred for 24 hours; Q13: After the reaction is completed and cooled to room temperature, wash the resulting mixture with deionized water 7-8 times and centrifuge at 5000 rpm for 5 min until the pH value of the supernatant is greater than 6; Q14: Ultrasonicate the dispersion for 30 minutes, and centrifuge the solution at 3500 rpm for 30 minutes to separate the supernatant, which is the desired photothermal conversion material; Q2: Preparation of TPU-PCL memory fiber; Q21: Weigh 1 g of thermoplastic polyurethane (TPU) and 1 g of polycaprolactone (PCL), add them to 10 mL of dimethylformamide (DMF), heat and stir in a 60°C water bath until completely dissolved to prepare a spinning solution. Q22: After the spinning solution is allowed to stand and degas, it is transferred to a 5 mL syringe and connected to a 22 G needle. Wet spinning is carried out at a rate of 7 mL / h. The coagulation bath is deionized water. During the spinning process, dimethylformamide (DMF) and deionized water are fully exchanged to form a fiber structure, and the resulting fiber is then naturally dried to remove surface moisture. Q23: After the fiber is completely dry, the pre-made supernatant is evenly applied to the fiber surface by brushing, and then naturally dried again to finally obtain a composite fiber with photothermal response capability.

[0027] This invention combines photothermal conversion materials with shape-memory polymer fibers to create photothermal-triggered smart fibers, offering a solution to the problem of intelligent fabric anti-counterfeiting. The photothermal conversion material achieves non-contact heating under illumination, offering advantages such as fast response, low energy consumption, and precise control.

[0028] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for preparing photothermally driven liquid metal microsphere-polymer shape memory fiber, comprising compounding liquid metal microspheres (LMP) with waterborne polyurethane (WPU) to form a coating slurry with photothermal responsiveness, which is then uniformly coated on the surface of thermoplastic polyurethane / polycaprolactone (TPU) / PCL shape memory fiber prepared by a wet spinning process to obtain a TPU-PCL / LMP-WPU composite fiber with photothermal responsiveness.

2. The method for preparing the photothermally driven liquid metal microsphere-polymer shape memory fiber according to claim 1, characterized in that: The preparation method comprises the following steps: S1: Preparation of LMP-WPU photosensitive materials; S11: 1 g of gallium-containing liquid metal was added to 250 mL of anhydrous ethanol and ultrasonically dispersed using a cell disruptor in an ice-water bath. The ultrasonic power was set to 50-70% and the ultrasonic time was set to 15-30 min to obtain a liquid metal microsphere LMP / ethanol mixture. S12: mixing liquid metal microspheres LMP and ethanol to prepare an LMP / ethanol mixture; centrifuging the mixture at a speed of 50–5000 rpm for 5 minutes; collecting the supernatant after centrifugation and drying it in a constant temperature drying oven at 60° C. to obtain liquid metal microsphere LMP powder; S13: Weigh 0.1 g of dried LMP powder, add it to 200 μL of 10-30 wt% aqueous polyurethane WPU solution, and stir thoroughly to prepare LMP-WPU photothermal responsive composite slurry; S2: Preparation of TPU-PCL memory fibers; S21: Weigh 1 g of thermoplastic polyurethane (TPU) and 1 g of polycaprolactone (PCL), add them to 10 mL of dimethylformamide (DMF), and heat and stir in a 60°C water bath until they are completely dissolved to prepare a spinning solution. S22: After the spinning solution is allowed to stand and degas, it is transferred to a 5 mL syringe and connected to a 19-22 G needle. Wet spinning is performed at a rate of 5-8 mL / h, and the coagulation bath is deionized water. During the spinning process, dimethylformamide (DMF) and deionized water are fully exchanged to form a fiber structure, and the resulting fiber is then naturally dried to remove surface moisture. S23: After the fiber is completely dry, the prefabricated LMP / WPU photothermal responsive composite slurry is evenly coated on the fiber surface by brushing, and then naturally dried again to finally obtain photothermally driven liquid metal microsphere-polymer shape memory TPU-PCL / LMP-WPU fiber.

3. The method for preparing the photothermally driven liquid metal microsphere-polymer shape memory fiber according to claim 2, characterized in that: The liquid alloy material containing gallium metal is gallium-indium alloy.

4. The method for preparing the photothermally driven liquid metal microsphere-polymer shape memory fiber according to claim 2, characterized in that: In step S12, the rotation speed of the centrifugal treatment is adjusted to obtain liquid metal microspheres with different particle size distributions, and the particle size distribution is 151.34±9.50-323.14±22.20 nm.

5. A method for preparing a photothermally driven liquid metal microsphere-polymer shape memory fiber, comprising a fiber matrix composed of TPU / PCL and a surface coating of a photothermal conversion material to produce a composite fiber with photothermal responsiveness. The specific steps are as follows: Q1: Preparation of photothermal conversion materials; Q11: Add 2 g of a material with photothermal conversion properties into 20 mL of 4.5-5 M HCl solution and dissolve it; Q12: Slowly add 2 g of Ti3AlC2 powder into the above mixed solution and o C and stir for 24-48 hours; Q13: After the reaction is completed and cooled to room temperature, the resulting mixture is washed several times with deionized water and centrifuged at 5000 rpm for 5-10 min until the pH value of the supernatant is greater than 6; Q14: Ultrasonicate the dispersion for 30-40 minutes, and centrifuge the solution at 3500-5000 rpm for 30 minutes to separate the supernatant, which is the desired photothermal conversion material; Q2: Preparation of TPU-PCL memory fiber; Q21: Weigh 1 g of thermoplastic polyurethane (TPU) and 1 g of polycaprolactone (PCL), add them to 10 mL of dimethylformamide (DMF), heat and stir in a 60°C water bath until completely dissolved to prepare a spinning solution. Q22: After the spinning solution is allowed to stand and degas, it is transferred to a 5 mL syringe and connected to a 19-22 G needle. Wet spinning is performed at a rate of 5-8 mL / h, and the coagulation bath is deionized water. During the spinning process, dimethylformamide (DMF) and deionized water are fully exchanged to form a fiber structure, and the resulting fiber is then naturally dried to remove surface moisture. Q23: After the fiber is completely dry, the pre-made supernatant is evenly applied to the fiber surface by brushing, and then naturally dried again to finally obtain a composite fiber with photothermal response capability.

6. The method for preparing the photothermally driven liquid metal microsphere-polymer shape memory fiber according to claim 5, characterized in that: The material having the light-to-heat conversion property is a two-dimensional transition metal carbide / nitride MXenes, or a carbon nanotube CNT.

7. A fabric comprising the photothermally driven liquid metal microsphere-polymer shape memory fiber prepared according to the preparation method according to any one of claims 2 to 6.

8. A photothermally driven liquid metal microsphere-polymer shape memory fiber prepared according to the preparation method according to any one of claims 2 to 6, used as an infrared anti-counterfeiting agent.

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