Intelligent temperature control light-colored fiber for comfortable heat management and preparation method of intelligent temperature control light-colored fiber

Abstract

The invention provides an intelligent temperature control light-colored fiber for comfortable heat management and a preparation method thereof, and belongs to the technical field of temperature response materials, the intelligent temperature control light-colored fiber provided by the invention is obtained through coaxial wet spinning, and comprises a core layer and a sheath layer wrapping the surface of the core layer; the core layer is composed of a high-molecular polymer and cesium tungsten bronze (CWO) nanoparticles; and the sheath layer is composed of a high-molecular polymer and vanadium dioxide (VO2) nanoparticles. The core layer can accommodate a large number of CWO nano-particles with excellent near-infrared absorption performance, the sheath layer containing VO2 nano-particles can serve as a photo-thermal control switch, the photo-thermal heating effect of the core layer is intelligently controlled by sensing the environment temperature change, in other words, in the cold environment, the photo-thermal effect of the fiber can be promoted, the heating effect is provided for the human body, and the near-infrared absorption performance of the fiber is improved. And in a hot environment, the photo-thermal heating effect of the fibers can be spontaneously reduced, accurate regulation and control of the temperature are realized, and the problem of overheating is avoided while the thermal comfort of a human body is improved by utilizing solar energy.

Description

Technical Field

[0001] The present invention belongs to the technical field of temperature-responsive materials, and particularly relates to an intelligent temperature-controlled light-colored fiber for comfortable thermal management. Background Art

[0002] Thermal comfort refers to the psychological state in which people feel satisfied in a specific thermal environment, that is, neither feeling too cold nor too hot. Maintaining thermal comfort is crucial for human health because abnormal fluctuations in the core body temperature may endanger life. When the core body temperature exceeds 38.3 °C or is lower than 35.0 °C, serious health problems may be triggered, even threatening life. In addition, the lack of thermal comfort will also affect labor productivity and lead to a reduction in industrial efficiency, thereby affecting economic development. Therefore, intelligent thermal comfort regulation is crucial for human energy management. At the same time, reasonably regulating the thermal comfort of the human body has a significant impact on the energy-saving effect of building heating, ventilation, and air-conditioning systems. Therefore, it is urgent to develop new strategies and solutions to effectively improve the level of human thermal comfort control.

[0003] Currently, personal thermal management heating fabrics are mainly divided into radiative heating fabrics and photothermal fabrics. For radiative heating fabrics, having a low transmittance in the mid-infrared will significantly inhibit the radiative heat dissipation of the human body. It can not only significantly save energy but also reduce heat loss to help the human body resist cold and avoid risks such as hypothermia. Radiative heating fabrics only reduce heat loss and are powerless to obtain external energy because they ignore that the solar spectrum concentrates most of the solar radiation energy. In recent years, with the continuous in-depth research on photothermal materials and the continuous breakthroughs in technologies such as photothermal evaporation and photothermal power generation, people have realized the cleanliness and effectiveness of solar energy. Many researchers have begun to combine photothermal materials with fabrics to develop photothermal fabrics that can directly utilize solar energy to increase the human body temperature outdoors in cold winters. However, the current development of photothermal fabrics mainly focuses on how to improve the photothermal conversion efficiency to increase the heating rate and the final saturation temperature, ignoring that the human body can only feel thermally comfortable within a suitable temperature range. Therefore, it is necessary to develop a self-heating fabric that can automatically regulate the temperature according to the ambient temperature.

[0004] Chinese Patent Publication No. CN118048711A discloses a photothermal fiber based on Mxene modification and its preparation method. In this invention, an aluminum niobium carbide dispersion liquid is mixed with a graphene oxide dispersion liquid through a hydrothermal self-assembly process to obtain an aluminum niobium carbide / graphene composite material, which is then mixed with polyethylene terephthalate and a photothermal fiber is obtained through electrospinning. The prepared photothermal fiber has a high photothermal conversion efficiency, good fiber morphology, and the aluminum niobium carbide / graphene composite material can be evenly dispersed in the photothermal fiber. Chinese Patent Publication No. CN118223185A provides a novel warm fabric and its preparation method. In this preparation method, a polyester material is used as the polymer main body, and Cs x WO3 nanoparticles are used as the photothermal conversion material, and a composite masterbatch is obtained through melt blending and extrusion. Then, composite polyester fibers are prepared through melt spinning technology. Subsequently, a novel warm fabric is woven by knitting technology in combination with a certain proportion of spandex filaments. This fabric not only has good light absorption and heat generation performance, but also solves the technical problems of easy shedding of the finishing textile coating structure and short service life by wrapping inorganic nanoparticles with organic polymers, ensuring the use stability and safety of the photothermal conversion nanoparticle material. Although the above-mentioned photothermal fiber has good photothermal performance, it cannot respond to changes in environmental temperature to achieve intelligent temperature control. For example, when the solar intensity fluctuates greatly, the above-mentioned photothermal fiber may generate overheating problems, restricting its application range and posing uncontrollable safety risks. For example, long-term contact of the skin with a low-temperature object at 41°C to 45°C is very likely to cause low-temperature burns. Low-temperature burns may cause damage to the skin surface and deep tissues, including skin cell death, nerve damage, and local blood circulation obstruction. In more serious cases, low-temperature burns can not only cause permanent scars, but also lead to hazards such as infection and loss of function. Therefore, for the promotion and application of photothermal materials, effective temperature intelligent control measures must be taken to ensure the safety of their use process.

[0005] Chinese Patent Publication No. CN118087280A discloses an intelligent bidirectional temperature - adaptive thermal management fabric, its preparation method and application. In this invention, a radiation cooling layer and a thermochromic phase - change microcapsule functional surface layer are successively coated on the surface of the fiber fabric. It can achieve adaptive intelligent switching according to the external temperature environment. That is, when the external environmental temperature is high, the fabric is in the cooling mode. The thermochromic phase - change microcapsules undergo a phase change to absorb the heat of the fabric and delay the rise of its temperature. At the same time, the thermochromic phase - change microcapsules are colorless in the polymer coating, making the thermal management fabric appear white. In the solar spectrum band, the solar radiation light can be strongly scattered by the bottom radiation cooling layer, so that the fabric surface has a high solar reflectivity, reducing the absorbed solar radiation heat. Combining with the high - heat - radiation - rate characteristic of the thermal management fabric itself, its surface temperature is thus reduced. On the contrary, when the external environmental temperature is low, the fabric enters the heat - preservation mode, and the phase - change microcapsules release heat through a phase change, thereby delaying the drop of the fabric temperature. At the same time, the thermochromic phase - change microcapsules appear black, making the fabric surface present a black appearance, so that it can absorb about 50% of the solar radiation energy in the visible light band. This not only weakens the influence of radiation cooling on the fabric temperature but also increases the solar radiation heat absorbed by the fabric surface. Although the above - mentioned intelligent temperature - adaptive thermal management fabric has a good temperature - regulation effect, there are still many defects. First of all, its temperature - regulation mechanism mainly realizes temperature regulation by controlling visible light. At high temperatures, the thermochromic phase - change microcapsules appear black to absorb heat, but the utilization of near - infrared light, which accounts for about 50% of the solar spectrum, is insufficient. Secondly, while regulating the temperature, the color of the clothing will continuously change between black and white with the environmental temperature, which is difficult to meet the personalized needs. Finally, commercially available thermochromic capsule materials usually have a relatively wide phase - change temperature range and a slow phase - change response time, and cannot achieve precise and rapid intelligent regulation. Especially during the process of environmental temperature change, the appearance color of the clothing often shows uneven color change. This uneven color change will lead to poor visual effects, giving people an impression of dirtiness. Moreover, due to the slow phase - change time, the temperature - regulation effect on human thermal comfort lags behind. Summary of the Invention

[0006] Aiming at the technical problems that personal thermal management fibers in the prior art rely on the photothermal effect and are difficult to cope with changing climate conditions, the temperature - control ability of thermochromic fibers is limited and it is difficult to achieve precise and rapid temperature control, and it is necessary to change the appearance color of the fibers for temperature regulation, etc. The present invention provides an intelligent temperature - control light - colored fiber for comfortable thermal management and its preparation method, which can adaptively regulate the photothermal heating effect according to the change of environmental temperature, and further realize zero - energy dynamic thermal management.

[0007] A preparation method of an intelligent temperature - control light - colored fiber for comfortable thermal management, comprising the following steps:

[0008] (1) Dissolve cesium tungsten bronze (CWO) nanoparticles and polymer Ⅰ in solvent Ⅰ to obtain a spinning solution containing cesium tungsten bronze nanoparticles;

[0009] (2) Dissolve vanadium dioxide (VO2) nanoparticles and polymer Ⅱ in solvent Ⅱ to obtain a spinning solution containing vanadium dioxide nanoparticles;

[0010] (3) Use the spinning solution containing cesium tungsten bronze nanoparticles as the core layer and the spinning solution containing vanadium dioxide nanoparticles as the sheath layer, and obtain fibers with a core-sheath structure through coaxial wet spinning. After drying, intelligent temperature-controlled light-colored fibers with a core-sheath structure are obtained.

[0011] The core layer can accommodate a large number of CWO nanoparticles with excellent near-infrared absorption performance, while the sheath layer containing VO2 nanoparticles can act as a photothermal regulation switch. By sensing the change of environmental temperature, it can intelligently regulate the photothermal heating effect of the core layer. That is, in a cold environment (below the phase transition temperature of VO2), it can promote the photothermal heating effect of the fiber, thus providing a comfortable heating effect for the human body. In a hot environment (above the phase transition temperature of VO2), it can spontaneously, accurately and quickly reduce the photothermal heating effect of the fiber, thus effectively utilizing solar energy to improve the thermal comfort of the human body and not causing overheating problems.

[0012] Preferably, to improve the dispersibility, in steps (1) and (2), CWO nanoparticles or VO2 nanoparticles can be first ultrasonically and stirred to disperse in the solvent. Preferably, the stirring time is 1 - 5 h, and the ultrasonic time is 0.5 - 2 h. Then add the polymer to disperse and dissolve it in the solvent, and the stirring and dissolving time is 2 - 24 h, and the dissolution temperature is room temperature (20 - 25 °C).

[0013] Both polymer Ⅰ and Ⅱ are polyurethane (TPU).

[0014] Both solvent Ⅰ and Ⅱ are N, N-dimethylformamide.

[0015] The average particle size of the cesium tungsten bronze nanoparticles is 50 - 500 nm. Cesium tungsten bronze nanoparticles are excellent photothermal materials mainly absorbing near-infrared light. Therefore, during the preparation of intelligent temperature-controlled light-colored fibers, adding cesium tungsten bronze nanoparticles can provide an excellent zero-energy heating effect for the human body in a cold environment.

[0016] The average particle size of the vanadium dioxide nanoparticles is 50 nm - 20 μm, and the phase transition temperature is -20 - 70 °C.

[0017] Preferably, the phase transition temperature of vanadium dioxide nanoparticles is one of 25, 35, 45, 55, and 68 °C. Vanadium dioxide nanoparticles are a metal-insulator phase change material, which has high transmittance to near-infrared before phase transition and high reflectivity to near-infrared after phase transition. By adjusting the doping concentrations of elements such as tungsten (W) and molybdenum (Mo), the phase transition temperature of vanadium dioxide can be adjusted in the range of about -20 °C to 70 °C. Therefore, according to different actual requirements, single vanadium dioxide nanoparticles with different phase transition temperatures or vanadium dioxide nanoparticles with multiple phase transition temperatures can be doped during the preparation of intelligent temperature-controlled light-colored fibers. Vanadium dioxide nanoparticles with different phase transition temperatures can exhibit different thermal management control effects according to different environmental temperatures.

[0018] In the spinning solution containing cesium tungsten bronze nanoparticles, the mass fraction of polymer I is 5-30%, and the addition amount of cesium tungsten bronze nanoparticles is 5-50 wt% of polymer I.

[0019] In the spinning solution containing vanadium dioxide nanoparticles, the mass fraction of polymer II is 5-30%, and the addition amount of vanadium dioxide nanoparticles is 5-50 wt% of polymer II.

[0020] The coaxial wet spinning is a conventional process in the art. Based on the basic principle of wet spinning, a coaxial nozzle is used to extrude two or more different spinning fluids from the inner and outer nozzles respectively to form a coaxial liquid flow structure. After entering the coagulation bath, due to the mass transfer between the solvent and the coagulant, the spinning fluid solidifies and forms a fiber with a coaxial structure. By controlling the diameters of the inner and outer nozzles, the thicknesses of the sheath layer and the core layer can be adjusted.

[0021] The coagulation bath for the coaxial wet spinning is water, and it is left standing at room temperature (20-25 °C) for 1-5 h to fully replace and remove the solvent; the drying is freeze-drying.

[0022] Preferably, the freeze-drying step is: first, freeze at -20 °C to -100 °C for 6-48 h, and then place it in a freeze-dryer for freeze-drying for 12-48 h.

[0023] In the spinning solution containing cesium tungsten bronze nanoparticles in step (1), a phase change energy storage material is also added.

[0024] The phase change energy storage material is selected from one of the commonly used personal thermal management phase change energy storage materials, such as lauric acid, stearic acid, paraffin, n-tetradecane, n-octadecane, polyethylene glycol, etc.

[0025] It should be noted here that the fibers with core-sheath structure design are not only conducive to the effective regulation of the photothermal effect of CWO nanoparticles in the core layer by VO2 nanoparticles in the sheath layer, thereby achieving precise and rapid intelligent temperature control, but also conducive to further adding phase change energy storage materials to the core layer to realize the integration of photothermal temperature control and phase change energy storage functions, thereby further optimizing the intelligent temperature control effect. Therefore, according to different actual requirements, different phase change temperature / different types of phase change energy storage materials can be added to the core layer during the preparation of intelligent temperature control light-colored fibers, and different thermal management regulation effects can be presented according to different environmental temperatures.

[0026] An intelligent temperature control light-colored fiber, the self-heating light-colored fiber has a coaxial structure, and includes a core layer containing cesium tungsten bronze nanoparticles and a sheath layer containing vanadium dioxide nanoparticles.

[0027] The average diameter of the self-heating light-colored fiber is 800-1200 um, the average radius of the core layer is 300-500 um, and the average thickness of the sheath layer is 50-150 um.

[0028] The beneficial effects of the present invention:

[0029] (1) The present invention provides an intelligent temperature control light-colored fiber, which can adaptively regulate the photothermal heating effect of CWO nanoparticles according to the environmental temperature through the high transmittance and high reflectance of near-infrared light before and after the phase change of vanadium dioxide, thereby realizing zero-energy dynamic thermal management. Specifically, in a cold environment, the fiber can spontaneously absorb sunlight to enhance its heating effect. Under the simulated solar illumination intensity of one sun (1 kw / m 2 )), after 2 minutes of illumination, the surface temperature of the intelligent temperature control fiber can quickly rise above 50 °C, and the average temperature is more than 20 °C higher than that of pure TPU fiber and commercial white cotton cloth. As the temperature of the fiber is higher than the VO2 phase change temperature, the fiber will slow down the heating rate, showing a temperature control effect about 2-6 °C lower than the surface temperature of the CWO photothermal composite fiber, avoiding the risk of overheating of most photothermal fabrics, and effectively maintaining the fiber temperature within the comfortable temperature range of the human body.

[0030] (2) Through the coaxial structure design, the present invention adds a photothermal material mainly absorbing near-infrared light to the core layer and adds VO2, a photothermal regulation material with different mass fractions and different phase change temperatures, to the sheath layer. It can not only ensure the rapid heating of the intelligent temperature control light-colored fiber at low temperature, but also achieve precise and rapid temperature control of the photothermal fiber, thereby optimizing the actual temperature control ability and providing more choices for a variety of low-temperature heating application scenarios, with broad application potential.

[0031] (3) The present invention utilizes a coaxial structure design, and can further add a phase change energy storage material to the core layer, combining intelligent temperature control with phase change energy storage, further expanding the application scenarios of intelligent temperature control light-colored fibers, providing effective guarantee for human thermal comfort, and not changing the color appearance of the clothing, effectively avoiding the problem of poor temperature control effect caused by uneven color change and slow response during the temperature regulation process of thermochromic fabrics, and at the same time overcoming its limitations in meeting the needs of personalized appearance and temperature regulation. The preparation method proposed by the present invention is simple and easy to be prepared by industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention, and those of ordinary skill in the art can obtain other drawings according to these drawings without creative efforts.

[0033] Figure 1 Optical photograph of the intelligent temperature control light-colored fiber prepared in Example 1;

[0034] Figure 2 Solar reflectance spectra of the intelligent temperature control light-colored fibers prepared in Examples 3 and 6 - 8, and the pure TPU fiber prepared in Comparative Example 1;

[0035] Figure 3 Thermal management effects (comparison chart of the photothermal saturation temperature and heating rate on the fabric surface under xenon lamp illumination with a light intensity of 1 kw / m 2 ) of the intelligent temperature control light-colored fibers prepared in Examples 2 - 5, the pure TPU fiber prepared in Comparative Example 1, and the CWO photothermal composite fiber prepared in Comparative Example 2.

[0036] Figure 4 Thermal management effects (comparison chart of the photothermal saturation temperature and heating rate on the fabric surface under xenon lamp illumination with a light intensity of 1 kw / m 2 ) of the intelligent temperature control light-colored fibers prepared in Examples 3 and 7 - 9, the pure TPU fiber prepared in Comparative Example 1, and the CWO photothermal composite fiber prepared in Comparative Example 2.

[0037] Figure 5 Outdoor thermal management performance curves of the intelligent temperature control light-colored fibers prepared in Examples 3 and 9, the pure TPU fiber prepared in Comparative Example 1, and the CWO photothermal composite fiber prepared in Comparative Example 2. Obtained by using a closed thermal insulation test chamber and continuously monitoring the temperature change in the chamber for 10 hours under natural sunlight irradiation conditions with a k-type thermocouple.

[0038] Figure 6Infrared thermal images of the intelligent temperature-controlled light-colored fibers prepared in Examples 3 and 9 under natural sunlight outdoors. (a) and (b) are the infrared thermal images at 0 min and 5 min of illumination, respectively. Detailed implementation manners

[0039] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0040] Example 1

[0041] An intelligent temperature-controlled light-colored fiber for comfortable thermal management, and the specific preparation method is as follows:

[0042] Step 1) First, dissolve the polyurethane resin in the N,N-dimethylformamide solvent to prepare two TPU solutions with a mass fraction of 15%.

[0043] Step 2) Uniformly disperse CWO nanoparticles with a weight fraction of 30% (relative to the weight of TPU) and an average particle size of 100 nm in one of the above TPU solutions to obtain a CWO / TPU solution, which is used as the core layer solution; uniformly disperse VO2 nanoparticles with a weight fraction of 30% (relative to the weight of TPU), a phase transition temperature of 68 °C, and an average particle size of 200 nm in the other TPU solution to obtain a TPU solution containing VO2 nanoparticles as the sheath layer solution; transfer the core layer solution and the sheath layer solution to two syringes respectively, and use an injection pump to squeeze the spinning solution into deionized water through a syringe equipped with a coaxial needle, immerse it in deionized water and let it stand for 2 h, and wait until the solvent is completely removed to obtain a fiber with a core-sheath structure.

[0044] Step 3) Transfer the fiber with the core-sheath structure obtained above to a refrigerator below -20 °C for freezing treatment for 8 h, and then transfer it to a freeze dryer for freeze drying for 24 h to obtain the intelligent temperature-controlled light-colored fiber.

[0045] Example 2

[0046] An intelligent temperature-controlled light-colored fiber for comfortable thermal management, and the specific preparation method is as follows:

[0047] Step 1) First, dissolve the polyurethane resin in the N,N-dimethylformamide solvent to prepare two TPU solutions with a mass fraction of 15%.

[0048] Step 2) Uniformly disperse CWO nanoparticles with a weight fraction of 30% (relative to the weight of TPU) and an average particle size of 100 nm in one portion of the above TPU solution to obtain a CWO / TPU solution, which is used as the core layer solution; uniformly disperse VO2 nanoparticles with a weight fraction of 30% (relative to the weight of TPU), a phase change temperature of 55 °C and an average particle size of 200 nm in the other portion of the above TPU solution to obtain a TPU solution containing VO2 nanoparticles as the sheath layer solution; transfer the core layer solution and the sheath layer solution to two syringes respectively, and use an injection pump to extrude the spinning solution into deionized water through a syringe equipped with a coaxial needle, immerse it in deionized water and let it stand for 2 h, and wait for the solvent to be completely removed to obtain fibers with a core-sheath structure.

[0049] Step 3) Transfer the above fibers with a core-sheath structure to a refrigerator below -20 °C first, freeze them for 8 h, and then transfer them to a freeze dryer for freeze drying for 24 h to obtain intelligent temperature-controlled light-colored fibers.

[0050] Example 3

[0051] An intelligent temperature-controlled light-colored fiber for comfortable thermal management, and the specific preparation method is as follows:

[0052] Step 1) First dissolve the polyurethane resin in an N,N-dimethylformamide solvent to prepare two TPU solutions with a mass fraction of 15%.

[0053] Step 2) Uniformly disperse CWO nanoparticles with a weight fraction of 30% (relative to the weight of TPU) and an average particle size of 100 nm in one portion of the above TPU solution to obtain a CWO / TPU solution, which is used as the core layer solution; uniformly disperse VO2 nanoparticles with a weight fraction of 30% (relative to the weight of TPU), a phase change temperature of 45 °C and an average particle size of 200 nm in the other portion of the above TPU solution to obtain a TPU solution containing VO2 nanoparticles as the sheath layer solution; transfer the core layer solution and the sheath layer solution to two syringes respectively, and use an injection pump to extrude the spinning solution into deionized water through a syringe equipped with a coaxial needle, immerse it in deionized water and let it stand for 2 h, and wait for the solvent to be completely removed to obtain fibers with a core-sheath structure.

[0054] Step 3) Transfer the above fibers with a core-sheath structure to a refrigerator below -20 °C first, freeze them for 8 h, and then transfer them to a freeze dryer for freeze drying for 24 h to obtain intelligent temperature-controlled light-colored fibers.

[0055] Example 4

[0056] An intelligent temperature-controlled light-colored fiber for comfortable thermal management, and the specific preparation method is as follows:

[0057] Step 1) First, dissolve the polyurethane resin in N,N-dimethylformamide solvent to prepare two TPU solutions with a mass fraction of 15%.

[0058] Step 2) Uniformly disperse CWO nanoparticles with a weight fraction of 30% (relative to the weight of TPU) and an average particle size of 100 nm in one of the above TPU solutions to obtain a CWO / TPU solution, which is used as the core layer solution; uniformly disperse VO2 nanoparticles with a weight fraction of 30% (relative to the weight of TPU), a phase change temperature of 35 °C and an average particle size of 200 nm in the other TPU solution to obtain a TPU solution containing VO2 nanoparticles as the sheath layer solution; transfer the core layer solution and the sheath layer solution into two syringes respectively, and use an injection pump to extrude the spinning solution into deionized water through a syringe equipped with a coaxial needle, immerse it in deionized water and let it stand for 2 h, and wait until the solvent is completely removed to obtain fibers with a core-sheath structure.

[0059] Step 3) Transfer the above fibers with a core-sheath structure to a refrigerator below -20 °C first, freeze them for 8 h, and then transfer them to a freeze dryer for freeze drying for 24 h to obtain intelligent temperature-controlled light-colored fibers.

[0060] Example 5

[0061] An intelligent temperature-controlled light-colored fiber for comfortable thermal management, and the specific preparation method is as follows:

[0062] Step 1) First, dissolve the polyurethane resin in N,N-dimethylformamide solvent to prepare two TPU solutions with a mass fraction of 15%.

[0063] Step 2) Uniformly disperse CWO nanoparticles with a weight fraction of 30% (relative to the weight of TPU) and an average particle size of 100 nm in one of the above TPU solutions to obtain a CWO / TPU solution, which is used as the core layer solution; uniformly disperse VO2 nanoparticles with a weight fraction of 30% (relative to the weight of TPU), a phase change temperature of 25 °C and an average particle size of 200 nm in the other TPU solution to obtain a TPU solution containing VO2 nanoparticles as the sheath layer solution; transfer the core layer solution and the sheath layer solution into two syringes respectively, and use an injection pump to extrude the spinning solution into deionized water through a syringe equipped with a coaxial needle, immerse it in deionized water and let it stand for 2 h, and wait until the solvent is completely removed to obtain fibers with a core-sheath structure.

[0064] Step 3) Transfer the above fibers with a core-sheath structure to a refrigerator below -20 °C first, freeze them for 8 h, and then transfer them to a freeze dryer for freeze drying for 24 h to obtain intelligent temperature-controlled light-colored fibers.

[0065] Example 6

[0066] An intelligent temperature - controlled light - colored fiber for comfortable thermal management, and the specific preparation method is as follows:

[0067] Step 1) First, dissolve polyurethane resin in N, N - dimethylformamide solvent to prepare two TPU solutions with a mass fraction of 15%.

[0068] Step 2) Uniformly disperse CWO nanoparticles with a weight fraction of 30% (relative to the weight of TPU) and an average particle size of 100 nm in one of the above - mentioned TPU solutions to obtain a CWO / TPU solution, which is used as the core - layer solution; uniformly disperse VO2 nanoparticles with a weight fraction of 20% (relative to the weight of TPU), a phase - change temperature of 45 °C and an average particle size of 200 nm in the other TPU solution to obtain a TPU solution containing VO2 nanoparticles as the sheath - layer solution; transfer the core - layer solution and the sheath - layer solution into two syringes respectively, and use an injection pump to extrude the spinning solution into deionized water through a syringe equipped with a coaxial needle, immerse it in deionized water and let it stand for 2 h, and wait until the solvent is completely removed to obtain fibers with a core - sheath structure.

[0069] Step 3) Transfer the fibers with the core - sheath structure obtained above to a refrigerator below - 20 °C for freeze - treatment for 8 h, and then transfer them to a freeze - dryer for freeze - drying for 24 h to obtain the intelligent temperature - controlled light - colored fiber.

[0070] Example 7

[0071] An intelligent temperature - controlled light - colored fiber for comfortable thermal management, and the specific preparation method is as follows:

[0072] Step 1) First, dissolve polyurethane resin in N, N - dimethylformamide solvent to prepare two TPU solutions with a mass fraction of 15%.

[0073] Step 2) Uniformly disperse CWO nanoparticles with a weight fraction of 30% (relative to the weight of TPU) and an average particle size of 100 nm in one of the above - mentioned TPU solutions to obtain a CWO / TPU solution, which is used as the core - layer solution; uniformly disperse VO2 nanoparticles with a weight fraction of 40% (relative to the weight of TPU), a phase - change temperature of 45 °C and an average particle size of 200 nm in the other TPU solution to obtain a TPU solution containing VO2 nanoparticles as the sheath - layer solution; transfer the core - layer solution and the sheath - layer solution into two syringes respectively, and use an injection pump to extrude the spinning solution into deionized water through a syringe equipped with a coaxial needle, immerse it in deionized water and let it stand for 2 h, and wait until the solvent is completely removed to obtain fibers with a core - sheath structure.

[0074] Step 3) Transfer the above fibers with a core-sheath structure to a refrigerator below -20°C and freeze them for 8 h, then transfer them to a freeze dryer and freeze-dry them for 24 h to obtain intelligent temperature-controlled light-colored fibers.

[0075] Example 8

[0076] An intelligent temperature-controlled light-colored fiber for comfortable thermal management, and the specific preparation method is as follows:

[0077] Step 1) First, dissolve the polyurethane resin in the N,N-dimethylformamide solvent to prepare two TPU solutions with a mass fraction of 15%.

[0078] Step 2) Uniformly disperse CWO nanoparticles with a weight fraction of 30% (relative to the weight of TPU) and an average particle size of 100 nm in one of the above TPU solutions to obtain a CWO / TPU solution, which is used as the core layer solution; uniformly disperse VO2 nanoparticles with a weight fraction of 50% (relative to the weight of TPU), a phase transition temperature of 45°C, and an average particle size of 200 nm in the other TPU solution to obtain a TPU solution containing VO2 nanoparticles as the sheath layer solution; transfer the core layer solution and the sheath layer solution to two syringes respectively, and use an injection pump to squeeze the spinning solution into deionized water through a syringe equipped with a coaxial needle, and immerse it in deionized water and let it stand for 2 h. Wait until the solvent is completely removed to obtain fibers with a core-sheath structure.

[0079] Step 3) Transfer the above fibers with a core-sheath structure to a refrigerator below -20°C and freeze them for 8 h, then transfer them to a freeze dryer and freeze-dry them for 24 h to obtain intelligent temperature-controlled light-colored fibers.

[0080] Example 9

[0081] An intelligent temperature-controlled light-colored fiber for comfortable thermal management, and the specific preparation method is as follows:

[0082] Step 1) First, dissolve the polyurethane resin in the N,N-dimethylformamide solvent to prepare two TPU solutions with a mass fraction of 15%.

[0083] Step 2) Uniformly disperse and dissolve CWO nanoparticles with a weight fraction of 30% (relative to the weight of TPU) and an average particle size of 100 nm and lauric acid (LA) powder with a weight fraction of 200% (relative to the weight of TPU) and a phase transition temperature of about 44 °C in the above TPU solution to obtain a CWO / LA / TPU solution, which is used as the core layer solution; uniformly disperse VO₂ nanoparticles with a weight fraction of 30% (relative to the weight of TPU), a phase transition temperature of 45 °C and an average particle size of 200 nm in the above TPU solution to obtain a TPU solution containing VO₂ nanoparticles as the sheath layer solution; transfer the core layer solution and the sheath layer solution to two syringes respectively, and use an injection pump to extrude the spinning solution into deionized water through a syringe equipped with a coaxial needle, immerse it in deionized water and let it stand for 2 h, and wait for the solvent to be completely removed to obtain fibers with a core-sheath structure.

[0084] Step 3) Transfer the above fibers with a core-sheath structure to a refrigerator below -20 °C first, freeze them for 8 h, and then transfer them to a freeze dryer for freeze drying for 24 h to obtain intelligent temperature-controlled light-colored fibers.

[0085] Comparative Example 1

[0086] This comparative example provides a preparation method of pure TPU fibers, and its specific preparation method is as follows:

[0087] Step 1) First dissolve the polyurethane resin in N,N-dimethylformamide solvent to obtain a 15% by mass TPU solution.

[0088] Step 2) Use the above TPU solution as the spinning solution, transfer the spinning solution to a syringe, and use an injection pump to extrude the spinning solution into deionized water through a syringe equipped with a single-axis needle with the same diameter as the coaxial needle in Example 1, immerse it in deionized water and let it stand for 2 h, and wait for the solvent to be completely removed to obtain fibers with a core-sheath structure.

[0089] Step 3) Transfer the above fibers with a core-sheath structure to a refrigerator below -20 °C first, freeze them for 8 h, and then transfer them to a freeze dryer for freeze drying for 24 h to obtain pure TPU fibers.

[0090] Comparative Example 2

[0091] This comparative example provides a preparation method of CWO photothermal composite fibers, and its specific preparation method is as follows:

[0092] Step 1) First dissolve the polyurethane resin in N,N-dimethylformamide solvent to obtain a 15% by mass TPU solution.

[0093] Step 2) CWO nanoparticles with a weight fraction of 30% (relative to the weight of TPU) and an average particle size of 100 nm were uniformly dispersed in the above TPU solution to obtain a CWO / TPU solution, which was used as a spinning solution. The spinning solution was transferred to a syringe, and the spinning solution was extruded into deionized water through a syringe equipped with a uniaxial needle with the same coaxial needle diameter as that in Example 1 by using an injection pump, and immersed in deionized water and left standing for 2 h. After thoroughly removing the solvent, fibers with a core-sheath structure were obtained.

[0094] Step 3) The above fibers with a core-sheath structure were first transferred to a refrigerator below -20 °C and freeze-treated for 8 h, and then transferred to a freeze dryer for freeze-drying for 24 h to obtain CWO photothermal composite fibers.

[0095] Performance Characterization

[0096] Figure 1 It is an optical photograph of the intelligent temperature-controlled light-colored fiber in Example 1; it can be observed from the figure that the intelligent temperature-controlled light-colored fiber has a light-colored appearance, which is mainly determined by the content of the sheath layer VO2. The higher the content, the darker the appearance color of the fiber. During the wet spinning process, phase separation results in a large number of pore structures inside the intelligent temperature-controlled light-colored fiber, and the coaxial spinning process makes the fiber have an obvious and complete core-sheath structure, which is beneficial for the CWO nanoparticles and VO2 nanoparticles in the fiber to be in different distribution positions, that is, the CWO nanoparticles are uniformly loaded in the core layer of the fiber, and the VO2 nanoparticles are uniformly loaded in the sheath layer of the fiber. Therefore, the VO2 nanoparticles in the sheath layer can regulate the light-heat effect of the CWO nanoparticles by adjusting the transmission and reflection of near-infrared light, and then regulate the temperature of the fabric. At the same time, since the concentration of TPU in the core layer and the sheath layer is the same, the compatibility of the two layers is very good, and the internal structure with the core layer and the sheath layer connected is beneficial to improving the mechanical properties.

[0097] Figure 2 It shows the solar reflectance spectra of the intelligent temperature-controlled light-colored fibers prepared in Example 3 and Examples 6-8 (30MF-45, 20MF-45, 40MF-45, 50MF-45 are shown in the figure in turn) and the pure TPU fiber prepared in Comparative Example 1 (TPU in the figure). By comparing and testing the intelligent temperature-controlled light-colored fibers in Example 3 and Examples 6-8 with the pure TPU fiber, it can be seen that at room temperature (20-25 °C), the order of solar reflectance from high to low is Example 6 > Example 3 > Example 7 > Example 8, indicating that for the intelligent temperature-controlled light-colored fibers with the same content of CWO nanoparticles in the core layer, their reflectance decreases with the increase of the VO2 content in the sheath layer, indicating that the VO2 in the sheath layer can improve the near-infrared absorption rate of the fiber, which is beneficial to improving its light-heat temperature-rising effect at low temperatures.

[0098] Figure 3Shows the intelligent temperature-controlled light-colored fibers prepared in Examples 2-5 (represented by MF-55, MF-45, MF-35, MF-25 in the figure), the pure TPU fiber prepared in Comparative Example 1 (TPU in the figure), and the CWO photothermal composite fiber prepared in Comparative Example 2 (CWO / TPU in the figure) under xenon lamp illumination with an illumination intensity of 1 kw / m 2 Comparison chart of the surface photothermal saturation temperature and heating rate of the fibers. The intelligent temperature-controlled light-colored fibers in Examples 2-5 were compared with the pure TPU fiber and the CWO photothermal composite fiber. When the temperature was below the VO2 phase transition temperature, the intelligent temperature-controlled light-colored fibers in Examples 2-5 all had a higher heating rate. When illuminated for 1 min, the surface temperature of the intelligent temperature-controlled light-colored fibers in Examples 2-3 could quickly rise to about 48 °C, indicating that in a cold outdoor environment, when the temperature was below the phase transition temperature of the vanadium dioxide added to the sheath layer, the cesium tungsten bronze nanoparticles had excellent photothermal effects, greatly improving the near-infrared absorption ability of the fabric. The intelligent temperature-controlled light-colored fibers could spontaneously absorb sunlight to increase the temperature and had excellent heating effects. When the temperature was higher than the VO2 phase transition temperature, the heating rate and saturation temperature of the intelligent temperature-controlled light-colored fibers in Examples 2-5 both decreased compared with the CWO photothermal composite fiber. Specifically, in the initial stage of heating under illumination, the heating rates of the intelligent temperature-controlled light-colored fibers in Examples 2-5 were all lower than that of the CWO photothermal composite fiber, and as the illumination time prolonged, the surface photothermal saturation temperatures of the intelligent temperature-controlled light-colored fibers in Examples 2-5 were 2 °C, 6 °C, 7 °C, and 8 °C lower than those of the CWO photothermal composite fiber respectively. This result shows that when the environmental temperature is higher than the vanadium dioxide phase transition temperature, the VO2 nanoparticles in the sheath layer can spontaneously reflect near-infrared light, greatly reducing the radiative absorption of the core-layer cesium tungsten bronze nanoparticles in the near-infrared band (0.8-2.5 μm) to reduce the photothermal effect, thereby preventing the fiber temperature from continuing to rise. The combination of the two avoids the risk of overheating of the photothermal fabric under intermittent and unstable sunlight illumination and effectively ensures the thermal comfort of the human body. In addition, the heating rate of the intelligent temperature-controlled light-colored fiber in Example 3 was lower than that of the intelligent temperature-controlled light-colored fiber in Example 2 in the early stage, higher than that of the intelligent temperature-controlled light-colored fibers in Examples 4 and 5, and the surface photothermal saturation temperature of the intelligent temperature-controlled light-colored fiber in Example 3 was lower than that of the intelligent temperature-controlled light-colored fiber in Example 2, higher than that of the intelligent temperature-controlled light-colored fibers in Examples 4 and 5, indicating that the heating rate and surface photothermal saturation temperature of the intelligent temperature-controlled light-colored fiber increase with the increase of the VO2 phase transition temperature. Therefore, according to the temperature regulation requirements, the temperature point can be artificially set to regulate the heating rate and surface temperature of the photothermal fabric to expand its application scenarios and optimize the intelligent temperature regulation effect.

[0099] Figure 4Shows the comparison chart of the surface photothermal saturation temperature and heating rate of the intelligent temperature-controlled light-colored fibers prepared in Example 3 and Examples 7-9 (successively represented by MF-45, 40MF-45, 50MF-45, and PCMF-45 in the figure), the pure TPU fiber prepared in Comparative Example 1 (TPU in the figure), and the CWO photothermal composite fiber in Comparative Example 2 (CWO / TPU in the figure) under xenon lamp illumination with an illumination intensity of 1 kw / m 2 The comparison chart of the surface photothermal saturation temperature and heating rate of the fabric under xenon lamp illumination with an illumination intensity of 1 kw / m². Comparative tests were carried out on the intelligent temperature-controlled light-colored fibers, pure TPU fibers, and CWO photothermal composite fibers in Example 3 and Examples 7-9. It can be seen that when the intelligent temperature-controlled light-colored fibers in Example 3 and Examples 8 and 9 are below the VO2 phase transition temperature, the heating rate of the intelligent temperature-controlled light-colored fiber in Example 3 is close to that of the CWO photothermal composite fiber in the early stage, lower than that of the intelligent temperature-controlled light-colored fiber in Example 8, and higher than that of the intelligent temperature-controlled light-colored fiber in Example 7. This indicates that in a cold outdoor environment, when the temperature is below the phase transition temperature of VO2, cesium tungsten bronze nanoparticles have excellent photothermal effects, greatly improving the near-infrared absorption ability of the fabric. The intelligent temperature-controlled light-colored fiber can spontaneously absorb sunlight to increase the temperature and has excellent heating effects. When the temperature is higher than the VO2 phase transition temperature, the heating rate and photothermal saturation temperature start to slow down compared with the CWO photothermal composite fabric. As the illumination time delays, the photothermal saturation temperature of the intelligent temperature-controlled light-colored fiber in Example 3 is the lowest compared with the intelligent temperature-controlled light-colored fibers in Examples 7 and 8, indicating the best temperature control effect. The results show that when the environmental temperature is higher than the VO2 phase transition temperature, the VO2 nanoparticles in the sheath layer can spontaneously reflect near-infrared light, greatly reducing the radiation absorption of the core layer CWO nanoparticles in the near-infrared band (0.8-2.5 μm) to reduce the photothermal effect and thus preventing the fabric temperature from continuing to rise. In addition, compared with Example 3, in Example 9, by adding lauric acid with a phase transition temperature of about 44 °C to the core layer, its heating rate is significantly reduced because lauric acid undergoes solid-liquid phase transition near 44 °C, absorbing and storing solar heat energy, thus delaying the temperature rise process.

[0100] Figure 5Shows the outdoor thermal management performance curves of the intelligent temperature-controlled light-colored fibers prepared in Examples 3 and 9, the pure TPU fibers prepared in Comparative Example 1, and the CWO photothermal composite fibers prepared in Comparative Example 2. The test was carried out using a closed heat insulation test chamber. Under the condition of natural sunlight irradiation, the temperature change in the chamber was continuously monitored for 10 hours, and the sampling interval was 1 second. By comparing and testing the intelligent temperature-controlled light-colored fibers, pure TPU fibers, and CWO photothermal composite fibers in Examples 3 and 9, it can be seen that the temperature rise rate in the chamber covered by the intelligent temperature-controlled light-colored fibers in Examples 3 and 9 is faster and the photothermal maximum temperature is higher (more than 10 °C higher) than that in the chamber covered by the pure TPU fibers, indicating that it has better low-temperature heating ability and can provide a warming effect for the human body in a cold environment. Compared with the CWO photothermal composite fibers, the temperature rise rate in the chamber covered by the intelligent temperature-controlled light-colored fibers in Examples 3 and 9 is reduced, and the photothermal maximum temperatures are reduced by 6.1 and 4.4 °C respectively, effectively avoiding the overheating problem.

[0101] Figure 6 Shows the infrared thermograms of the intelligent temperature-controlled light-colored fibers prepared in Examples 3 and 9 under natural sunlight. Testing the intelligent temperature-controlled light-colored fibers in Examples 3 and 9 found that even outdoors with a relatively high wind speed, after 5 minutes of illumination, the surface temperatures of the two increased by 5.8 and 6.4 °C respectively, indicating that both have good photothermal temperature rise effects.

[0102] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A preparation method of intelligent temperature-controlled warm light-colored fibers for comfortable thermal management, characterized in that, It includes the following steps: (1) Disperse and dissolve cesium tungsten bronze nanoparticles and polymer Ⅰ in solvent Ⅰ to obtain a spinning solution containing cesium tungsten bronze nanoparticles; (2) Disperse and dissolve vanadium dioxide nanoparticles and polymer Ⅱ in solvent Ⅱ to obtain a spinning solution containing vanadium dioxide nanoparticles; (3) Use the spinning solution containing cesium tungsten bronze nanoparticles as the core layer and the spinning solution containing vanadium dioxide nanoparticles as the sheath layer, and obtain fibers with a core-sheath structure through coaxial wet spinning, and then obtain self-heating light-colored fibers with a core-sheath structure after drying.

2. The preparation method of the intelligent temperature-controlled light-colored fiber for comfortable thermal management according to claim 1, wherein, Both polymer Ⅰ and polymer Ⅱ are polyurethane.

3. The preparation method of the intelligent temperature-controlled light-colored fiber for comfortable thermal management according to claim 2, characterized in that, Both solvent Ⅰ and solvent Ⅱ are N,N-dimethylformamide.

4. The preparation method of the intelligent temperature-controlled light-colored fiber for comfortable thermal management according to claim 1, characterized in that, The average particle size of the cesium tungsten bronze nanoparticles is 50 - 500 nm; the average particle size of the vanadium dioxide nanoparticles is 50 nm - 20 μm, and the phase change temperature is -20 - 70 °C.

5. The preparation method of the intelligent temperature-controlled light-colored fiber for comfortable thermal management according to claim 1, characterized in that, In the spinning solution containing cesium tungsten bronze nanoparticles, the mass fraction of polymer Ⅰ is 5 - 30%, and the addition amount of cesium tungsten bronze nanoparticles is 5 - 50 wt% of polymer Ⅰ.

6. The preparation method of the intelligent temperature-controlled light-colored fiber for comfortable thermal management according to claim 1, wherein, In the spinning solution containing vanadium dioxide nanoparticles, the mass fraction of polymer Ⅱ is 5 - 30%, and the addition amount of vanadium dioxide nanoparticles is 5 - 50 wt% of polymer Ⅱ.

7. The preparation method of the intelligent temperature-controlled light-colored fiber for comfortable thermal management according to claim 1, characterized in that, The coagulation bath for the coaxial wet spinning is water; the drying is freeze-drying.

8. The preparation method of the intelligent temperature-controlled light-colored fiber for comfortable thermal management according to any one of claims 1-7, characterized in that, In step (1), the spinning solution containing cesium tungsten bronze nanoparticles further contains a phase change energy storage material.

9. The intelligent temperature-controlled light-colored fiber for comfortable thermal management prepared by the method according to any one of claims 1-8, characterized in that, The self-heating light-colored fiber has a coaxial structure, including a core layer containing cesium tungsten bronze nanoparticles and a sheath layer containing vanadium dioxide nanoparticles.

10. The intelligent temperature-controlled light-colored fiber for comfortable thermal management according to claim 9, characterized in that, The average diameter of the intelligent temperature-controlled light-colored fiber is 800 - 1200 μm, the average radius of the core layer is 300 - 500 μm, and the average thickness of the sheath layer is 50 - 150 μm.

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