Wearable fiber membrane with all-weather passive cooling and heat preservation functions and preparation method of wearable fiber membrane

Abstract

The invention relates to an all-weather wearable fiber membrane with passive cooling and heat preservation functions and a preparation method thereof.The method comprises the steps that firstly, polyether amine is modified through gamma-glycidyl ether oxypropyl trimethoxy silane and then reacts with nanometer aluminum oxide to prepare aluminum oxide fluid, thermoplastic polyurethane is dissolved in a mixed organic solvent, and the mixed organic solvent is added into the modified polyether amine to prepare the all-weather wearable fiber membrane with the passive cooling and heat preservation functions. The preparation method comprises the following steps: preparing a thermoplastic polyurethane electrospinning solution, carrying out electrospinning on an upper fibrous membrane by using the thermoplastic polyurethane solution without aluminum oxide fluid through a coaxial electrospinning process, and carrying out electrospinning on a lower fibrous membrane by using the thermoplastic polyurethane solution containing the aluminum oxide fluid as a shell layer and a glycerol / aqueous solution as a core layer, and treating to remove a core layer and keep a hollow structure, thereby finally obtaining the Janus fiber membrane with high sunlight reflectivity and ultralow thermal conductivity. According to the invention, the technical bottleneck that the traditional material is difficult to collaboratively integrate between cooling and heat preservation functions is successfully solved, and multifunctional integration of efficient heat management in an outdoor all-weather environment is realized.

Description

Technical Field

[0001] This invention relates to the field of intelligent thermal management and wearable technology, specifically to a wearable fiber membrane with both passive cooling and heat preservation functions in all weather conditions and its preparation method. Background Technology

[0002] With the rapid popularization of wearable fabrics in outdoor sports, medical monitoring, and military protection, users are placing higher demands on the thermal management functions of smart textiles. Ideal wearable materials should possess environmental adaptability: under high daytime temperatures, passive cooling technologies (such as high solar reflectivity) should reduce solar heat gain to avoid overheating and discomfort; at night or in low-temperature environments, insulation technologies (such as low thermal conductivity structures) are needed to suppress body heat loss and maintain thermal comfort. Currently, some progress has been made in single-function materials (such as reflective layers with added inorganic particles or aerogel insulation layers), but integrating cooling and insulation functions synergistically into the same flexible substrate still faces significant challenges. Existing research often employs physical composite strategies (such as lamination, blending, or simple coatings), which, while achieving local functional optimization, often lead to performance degradation due to material interface incompatibility and poor structural stability, making it difficult to meet the long-term reliability and comfort requirements of dynamic wearable scenarios.

[0003] The main technical bottlenecks are reflected in three aspects: First, there are inherent conflicts in the material properties. Passive cooling relies on high-refractive-index inorganic nanoparticles (such as alumina and titanium dioxide) to enhance sunlight reflection, but excessive addition can easily lead to a decrease in fiber flexibility and stress concentration at the interface. On the other hand, the heat preservation function requires the construction of a high-porosity hollow structure to reduce thermal conductivity. Such structures are prone to collapse during processing due to solvent erosion, mechanical force, or drying shrinkage, affecting durability. Second, there is insufficient process compatibility. Although traditional methods such as coaxial electrospinning can construct hollow fibers, the core template (such as glycerol) is limited. If the removal process of inorganic particles (in aqueous solution) is not properly controlled, it is easy to leave impurities or disrupt the continuity of pores, causing the hollow structure to collapse. At the same time, it is difficult to ensure the uniformity of dispersion of inorganic particles in the polymer matrix, which can easily agglomerate and block the fiber pores, weakening the air permeability. Finally, the functions are mutually restrictive. Simple functional superposition may lead to an imbalance in overall performance. For example, although the high reflectivity layer improves the cooling efficiency, it may block the pores and affect the permeability of moisture. On the other hand, excessive hollowing enhances the heat preservation, but reduces the mechanical strength, and cannot meet the comprehensive requirements of lightweight, flexibility and multi-functional integration in practical applications.

[0004] To address the aforementioned bottlenecks, the development of an integrated fiber membrane capable of dynamically balancing cooling and insulation functions has become an urgent industry need. This invention aims to overcome the limitations of traditional materials through molecular design (such as polyetheramine modification to improve interfacial compatibility) and process innovation (such as coaxial spinning and post-processing synergistic structural control). On one hand, by modifying alumina nanoparticles with fluid, the alumina nanoparticles are uniformly dispersed within the matrix, constructing a stable reflective layer on the fiber surface to achieve highly efficient solar reflection (reflectivity ≥94%). Simultaneously, the addition of alumina fluid significantly improves the mechanical properties of the fiber membrane itself (elongation at break ≥820%). On the other hand, by controllably removing the core layer template and fixing the hollow structure, a continuous thermal insulation network is formed (thermal conductivity <0.015 W / (m·K)). This multi-scale structural design not only solves the functional synergy problem but also provides a smart solution for wearable fabrics that requires no external energy, is flexible and breathable, aligning with the development trends of green, low-carbon, and personalized customization. Summary of the Invention

[0005] In view of the technical problems existing in the background art, the present invention provides a wearable fiber membrane with both passive cooling and heat preservation functions and its preparation method, aiming to solve the core technical problem of the difficulty in synergistic integration of cooling and heat preservation functions through molecular modification and structural design.

[0006] The technical solution of the present invention is as follows: A method for preparing a wearable fiber membrane with both passive cooling and heat preservation functions in all weather conditions includes the following steps: S1. Dissolve polyetheramine in methanol to prepare a polyetheramine solution, then add γ-glycidoxypropyltrimethoxysilane to react and obtain a modified polyetheramine solution; S2. The alumina nanoparticles are mixed and reacted with the modified polyetheramine solution to obtain an alumina fluid; S3. Dissolve thermoplastic polyurethane in a mixed solvent of N,N-dimethylformamide and tetrahydrofuran to prepare a thermoplastic polyurethane electrospinning solution; S4. Using coaxial electrospinning technology, first spin the thermoplastic polyurethane electrospinning solution without added alumina fluid as the core layer base, and then spin the thermoplastic polyurethane electrospinning solution containing alumina fluid as the shell layer to form a double-layer fiber membrane. S5. The double-layer fiber membrane is soaked in deionized water to remove the core layer, then soaked in tert-butanol / water solution and freeze-dried to maintain the hollow structure, thus obtaining a wearable fiber membrane with all-weather passive cooling and heat preservation functions.

[0007] Furthermore, in step S1, the mass-to-volume ratio of the polyetheramine to methanol is 1:5 to 1:10 (g / mL), the reaction temperature is 40 to 60°C, and the reaction time is 20 to 28 hours.

[0008] Furthermore, the mass ratio of the γ-glycidoxypropyltrimethoxysilane to the polyetheramine is 1:5 to 1:10.

[0009] Furthermore, in step S2, the amount of alumina nanoparticles added is 5-15% of the total mass of the modified polyetheramine.

[0010] Furthermore, in step S3, the volume ratio of N,N-dimethylformamide to tetrahydrofuran is 1:1 to 1:2, and the concentration of the thermoplastic polyurethane electrospinning solution is 25 to 35 wt%.

[0011] Furthermore, in step S4, the core layer of the coaxial electrospinning is a mixed solution of glycerol and water, with a mass ratio of glycerol to water of 9:1 to 9.5:0.5, and the shell layer is a thermoplastic polyurethane electrospinning solution containing alumina fluid, wherein the alumina fluid accounts for 5 to 15% of the mass of the thermoplastic polyurethane.

[0012] Furthermore, the process parameters for the coaxial electrospinning are as follows: core layer advance speed 0.5~1.5 mL / h, shell layer advance speed 0.8~1.2 mL / h, spinning voltage 10~20 kV, and receiving distance 10~20 cm.

[0013] Furthermore, in step S5, the soaking time in deionized water is 20-28 hours, the volume concentration of tert-butanol / water solution is 20-30%, and the soaking time is 2-6 hours.

[0014] Furthermore, the thermal conductivity of the fiber membrane is less than 0.015 W / (m·K).

[0015] A wearable fiber membrane with both passive cooling and heat preservation functions in all weather conditions is prepared by the above method.

[0016] The beneficial effects of this invention are as follows: This invention provides a wearable fiber membrane with both passive cooling and heat preservation functions in all weather conditions, and its preparation method, belonging to the fields of intelligent thermal management and wearable technology. By dissolving polyetheramine in methanol, reacting it with γ-glycidyl etheroxypropyltrimethoxysilane, and then reacting it with alumina nanoparticles, an alumina fluid is obtained. A thermoplastic polyurethane electrospinning solution is prepared by dissolving thermoplastic polyurethane in a mixed organic solvent. The upper fiber membrane is electrospun using a coaxial electrospinning process with the thermoplastic polyurethane solution without alumina fluid. The lower fiber membrane is formed by using a thermoplastic polyurethane solution containing alumina fluid as the shell layer and a glycerol / water solution as the core layer. The core layer is then removed through post-treatment while maintaining the hollow structure, ultimately yielding a Janus fiber membrane with both high solar reflectivity (for passive cooling) and ultra-low thermal conductivity (for nighttime heat preservation). This invention successfully solves the technical bottleneck of traditional materials' difficulty in synergistically integrating cooling and heat preservation functions, achieving multifunctional integration for efficient thermal management in outdoor all-weather environments.

[0017] This invention aims to overcome the limitations of traditional materials through molecular design (such as polyetheramine modification to improve interfacial compatibility) and process innovation (such as coaxial spinning and post-processing synergistic control of structure). On the one hand, by modifying alumina nanoparticles into a fluid, the alumina nanoparticles are uniformly dispersed in the matrix, constructing a stable reflective layer on the fiber surface to achieve highly efficient solar reflection (reflectivity ≥94%). At the same time, the addition of alumina fluid significantly improves the mechanical properties of the fiber membrane itself (elongation at break ≥820%). On the other hand, by controllably removing the core layer template and fixing the hollow structure, a continuous thermal insulation network is formed (thermal conductivity <0.015 W / (m·K)). This multi-scale structural design not only solves the functional synergy problem but also provides a smart solution for wearable fabrics that requires no external energy, is flexible and breathable, and aligns with the development trends of green, low-carbon, and personalized customization.

[0018] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0019] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the present invention will be briefly described below. Obviously, the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0020] Figure 1A schematic diagram illustrating the preparation method of the wearable fiber membrane with both passive cooling and heat preservation functions provided in this embodiment of the invention; Figure 2 This is a bar chart showing the passive cooling of fiber membranes with different alumina fluid contents in embodiments of the present invention; Figure 3 The graph shows the solar reflectance variation curves of HPUA (upper layer solid thermoplastic polyurethane fiber, lower shell layer thermoplastic polyurethane / alumina fluid hollow fiber), HPU (upper layer solid thermoplastic polyurethane fiber, lower shell layer thermoplastic polyurethane hollow fiber) and PU (pure solid thermoplastic polyurethane fiber) fiber membranes in the solar radiation band in Embodiment 4 of the present invention. Figure 4 These are infrared thermal images of the HPUA fiber membrane and commercially available Cotton in an outdoor environment, as shown in Example 4 of this invention. Figure 5 These are SEM images of bilayer fiber membranes with different core layer pushing speeds obtained in Comparative Example 2 of this invention. Figure 6 The thermal conductivity variation curves of the bilayer fiber membranes with different core layer pushing speeds obtained in Comparative Example 2 of this invention are shown. Figure 7 The thermal insulation performance of HPUA fiber membrane and commercial Cotton obtained in Example 2 of this invention at night outdoors; Explanation of reference numerals in the attached figures: 1. Thermoplastic polyurethane fiber layer; 2. Thermoplastic polyurethane / alumina fluid hollow fiber layer. Detailed Implementation

[0021] The embodiments of the technical solution of the present invention will now be described in detail with reference to the accompanying drawings. These embodiments are merely illustrative of the technical solution of the present invention and are therefore intended to limit the scope of protection of the present invention.

[0022] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used in this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention; the terms “comprising” and “having”, and any variations thereof, in the specification, claims and foregoing description of the invention, are intended to cover non-exclusive inclusion.

[0023] In the description of the embodiments of this invention, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this invention, "multiple" means two or more, unless otherwise explicitly defined.

[0024] In this invention, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this invention can be combined with other embodiments.

[0025] The integration of passive cooling and insulation functions is of great significance to wearable thermal management technology, but it faces severe challenges. The core bottleneck lies in the mismatch of material properties and structural incompatibility between the cooling and insulation layers. This is mainly manifested in the tendency of inorganic functional particles to agglomerate, affecting reflection efficiency, while hollow structures are prone to collapse during processing, weakening insulation performance, and weak interlayer bonding leading to insufficient durability. Existing technologies, such as physical blending or simple composites, can achieve single functions, but they generally suffer from mutual performance constraints and poor long-term stability, failing to meet the comprehensive requirements of comfort, lightweight, and multifunctional integration in practical applications.

[0026] To address the technical problems of mutual performance inhibition, low structural stability, and poor environmental adaptability caused by material conflicts and process incompatibility between cooling and heat preservation functions, this invention provides a wearable fiber membrane with both passive cooling and heat preservation functions and its preparation method. Specifically, by modifying alumina nanoparticles into a fluid, the alumina nanoparticles are firmly dispersed in the fiber shell to construct a high-reflectivity structure. Simultaneously, a stable hollow network is formed through coaxial spinning and post-processing. This achieves synergistic high-efficiency solar reflection and ultra-low thermal conductivity within a single fiber membrane, ensuring the structural integrity and functional durability of the device under dynamic wear conditions.

[0027] In a first aspect, embodiments of the present invention provide a method for preparing a wearable fiber membrane that combines passive cooling and heat preservation functions, comprising the following steps: S1. Dissolve polyetheramine in methanol to prepare a polyetheramine solution, then add γ-glycidoxypropyltrimethoxysilane to react and obtain modified polyetheramine; S2. The alumina nanoparticles are mixed and reacted with the modified polyetheramine solution to obtain an alumina fluid; S3. Dissolve thermoplastic polyurethane in a mixed solvent of N,N-dimethylformamide and tetrahydrofuran to prepare a thermoplastic polyurethane electrospinning solution; S4. Using coaxial electrospinning technology, first spin the thermoplastic polyurethane electrospinning solution without added alumina fluid as the core layer base, and then spin the thermoplastic polyurethane electrospinning solution containing alumina fluid as the shell layer to form a double-layer fiber membrane. S5. The double-layer fiber membrane is soaked in deionized water to remove the core layer, and then soaked in tert-butanol / water solution to maintain the hollow structure, thereby obtaining a wearable fiber membrane with both passive cooling and heat preservation functions.

[0028] In the technical solution of this invention, a strategy combining coaxial electrospinning and post-processing is adopted. First, an alumina fluid is constructed through molecular modification, utilizing its amphiphilic properties to achieve stable dispersion of alumina nanoparticles in solution and matrix. Then, a bilayer fiber structure is formed through coaxial spinning, with a soluble glycerol / water solution as the core template and a thermoplastic polyurethane containing alumina fluid as the shell. Finally, a mild post-processing is performed to remove the core layer and lock the pores, successfully constructing a multifunctional fiber membrane with a biomimetic hollow network (hereinafter referred to as PTA fiber membrane for ease of expression). This structure not only endows the fiber membrane with a solar reflectivity of over 94%, effectively blocking the daytime solar radiation heat gain and achieving a passive cooling effect, but also, thanks to the ultra-low thermal conductivity of the hollow network (below 0.015 W / (m·K)), it suppresses heat loss at night or in low-temperature environments, achieving a long-term heat preservation function. In addition, the fiber membrane has excellent flexibility, breathability and mechanical durability, successfully overcoming the technical contradiction of traditional materials in that it is difficult to optimize cooling and heat preservation performance in a coordinated manner, and providing wearable devices with an environmentally adaptive intelligent thermal management solution.

[0029] Furthermore, in some embodiments, in step S1, the mass-to-volume ratio of the polyetheramine to methanol is 1:5 to 1:10 (g / mL), the reaction temperature is 40 to 60°C, and the reaction time is 20 to 28 hours.

[0030] In the technical solution of this invention, a suitable mass-to-volume ratio ensures the complete dissolution of polyetheramine in methanol, providing a homogeneous environment for subsequent modification reactions. The reaction temperature of 40–60°C and the reaction time of 20–28 hours ensure sufficient reaction between γ-glycidoxypropyltrimethoxysilane and the active sites on the polyetheramine molecular chain, forming stable linkages, thereby endowing alumina nanoparticles with excellent interfacial compatibility and dispersibility. Too low a temperature or too short a time may lead to incomplete reaction, affecting fluid properties; too high a temperature may easily cause solvent evaporation or side reactions.

[0031] Furthermore, in some embodiments, the mass ratio of the γ-glycidoxypropyltrimethoxysilane to the polyetheramine is 1:5 to 1:10.

[0032] In the technical solution of this invention embodiment, this mass ratio range ensures that the silane coupling agent can fully modify the polyetheramine molecular chain, introducing hydrophobic groups to enhance the interaction with alumina, while avoiding self-condensation or abnormal increase in fluid viscosity caused by excessive addition. By precisely controlling this ratio, the amphiphilic balance of the fluid can be optimized, improving its dispersion ability of inorganic particles in solution and matrix.

[0033] Furthermore, in some embodiments, in step S2, the amount of alumina nanoparticles added is 5-15% of the total mass of the modified polyetheramine.

[0034] In the technical solution of this invention embodiment, the addition amount of 5-15% ensures the uniform dispersion of alumina fluid in the substrate, forming high-density reflective sites, while preventing agglomeration, increased viscosity, or decreased fluid flowability caused by excessive particles. This range helps maintain a stable jet morphology during subsequent spinning, ensuring the optical uniformity and mechanical properties of the fiber shell.

[0035] Furthermore, in some embodiments, in step S3, the volume ratio of N,N-dimethylformamide to tetrahydrofuran is 1:1 to 1:2, and the concentration of the thermoplastic polyurethane electrospinning solution is 25 to 35 wt%.

[0036] In the technical solution of this invention, the mixed solvent of N,N-dimethylformamide and tetrahydrofuran synergistically regulates the volatility and solubility of the solution: N,N-dimethylformamide, as a high-boiling-point solvent, ensures the full dissolution of thermoplastic polyurethane and maintains the conductivity of the solution, while tetrahydrofuran, as a low-boiling-point solvent, promotes rapid solidification of the jet and avoids fiber adhesion. A thermoplastic polyurethane concentration of 25~35wt% provides a suitable degree of chain entanglement, which can form continuous fibers and prevent spinning difficulties or uneven fiber diameter caused by excessive concentration.

[0037] Furthermore, in some embodiments, in step S4, the core layer of the coaxial electrospinning is a mixed solution of glycerol and water, with a mass ratio of glycerol to water of 9:1 to 9.5:0.5, and the shell layer is a thermoplastic polyurethane electrospinning solution containing alumina fluid, wherein the alumina fluid accounts for 5 to 15% of the mass of the thermoplastic polyurethane.

[0038] In the technical solution of this invention embodiment, the specific ratio of glycerol to water ensures that the core template has moderate viscosity and solubility, facilitating subsequent removal; while the amount of alumina fluid added to the shell layer (5~15%) balances the reflective function and processing feasibility. Excessive fluid will increase the shell layer viscosity and affect spinning stability; too little fluid will prevent the formation of a continuous reflective network. Specifically, the process parameters for coaxial electrospinning can be controlled as follows: core layer advance speed 0.5~1.5 mL / h, shell layer advance speed 0.8~1.2 mL / h, spinning voltage 10~20 kV, and receiving distance 10~20 cm.

[0039] Furthermore, in some embodiments, in step S5, the deionized water soaking time is 20-28 hours, the volume concentration of tert-butanol / water solution is 20-30%, and the soaking time is 2-6 hours.

[0040] In the technical solution of this invention embodiment, soaking in deionized water for 20-28 hours ensures the complete dissolution and removal of the core layer glycerol / water template, forming a through-hole structure; while a 20-30% tert-butanol solution, under gentle treatment for 2-6 hours, effectively prevents the collapse of the hollow network during the drying process by displacing water and locking the pores. Too low a concentration or too short a time may lead to insufficient structural fixation; too high a concentration may easily cause fiber swelling or deformation.

[0041] Secondly, embodiments of the present invention provide a wearable fiber membrane that combines passive cooling and heat preservation functions, which is prepared by the preparation method described in the first aspect.

[0042] In the technical solution of this invention, a multifunctional fiber membrane with gradient and hollow structures was successfully developed through molecular design, fluid control and multi-scale process innovation. This achieved a deep coupling of cooling and heat preservation performance, while also taking into account lightweight, flexibility and wearing comfort. This has important value for promoting the application of textiles in all-weather outdoor protection and other fields.

[0043] The following are some specific embodiments. It should be noted that the embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0044] Example 1

[0045] This invention provides a method for preparing a wearable fiber membrane with both passive cooling and heat preservation functions in all weather conditions, comprising the following steps: S1. Dissolve 8.7 g of polyetheramine (Mn=2000) in 45 mL of methanol and stir at room temperature. Then, dissolve 1 g of γ-glycidoxypropyltrimethoxysilane in 48 mL (5 wt%) of methanol and add it dropwise to the polyetheramine / methanol solution with vigorous stirring. Stir the mixture at 50 °C for 24 h. S2. Add 0.2g of alumina nanoparticles to the solution after the above reaction and stir at 50℃ for 24 h. Centrifuge the solution after the reaction, take the supernatant, dialyze the solution with deionized water as the replacement solution for 4 days, and dry to obtain alumina fluid. S3. Prepare a 30% thermoplastic polyurethane electrospinning solution by mixing 6g of thermoplastic polyurethane (85A) with 14g of N,N-dimethylformamide:tetrahydrofuran in a 1:1 ratio of organic solvent. Prepare a thermoplastic polyurethane / alumina fluid electrospinning solution by mixing 0g of alumina fluid with 10g of the 30% thermoplastic polyurethane electrospinning solution. Prepare a glycerol / water solution by mixing 9.5g of glycerol and 0.5g of water.

[0046] S4. First, electrospinning a 30% thermoplastic polyurethane electrospinning solution for 2 hours using a 22G needle under conditions of positive voltage 9.5kV, negative voltage 0.5kV, feed rate 1mL / h, and receiving distance 10cm, yielding the upper fiber layer. Then, using a coaxial electrospinning process, electrospinning a thermoplastic polyurethane / alumina fluid electrospinning solution as the shell layer and a glycerol / aqueous solution as the core layer, using a side-shaft tube type 22 / 17G needle, under conditions of positive voltage 10kV, negative voltage 0.5kV, shell feed rate 1mL / h, core feed rate 0.3mL / h, and receiving distance 10cm, yielding the lower fiber layer.

[0047] S5. The double-layer fiber membrane is soaked in deionized water for 24 hours to remove the core layer, then soaked in a 25% tert-butanol / water solution for 24 hours, and then freeze-dried to maintain the hollow structure, thus obtaining a wearable fiber membrane with both passive cooling and heat preservation functions. Example 2

[0048] This embodiment provides a method for preparing a wearable fiber membrane with both passive cooling and heat preservation functions in all weather conditions. Compared with Example 1, the only difference is that in step S3, the alumina fluid is 0.1579g and the alumina fluid content is 5% of the thermoplastic polyurethane content. Other experimental parameters and conditions are basically the same as in Example 1, and will not be repeated here.

[0049] Example 3

[0050] This embodiment provides a method for preparing a wearable fiber membrane with both passive cooling and heat preservation functions in all weather conditions. Compared with Example 1, the only difference is that the alumina fluid is 0.2432g and the alumina fluid content is 7.5% of the thermoplastic polyurethane content. Other experimental parameters and conditions are basically the same as those in Example 1, and will not be repeated here.

[0051] Example 4

[0052] This embodiment provides a method for preparing a wearable fiber membrane with both passive cooling and heat preservation functions in all weather conditions. Compared with Example 1, the only difference is that in step S3, the alumina fluid is 0.3333g and the alumina fluid content is 10% of the thermoplastic polyurethane content. Other experimental parameters and conditions are basically the same as in Example 1, and will not be repeated here.

[0053] Example 5

[0054] This embodiment provides a method for preparing a wearable fiber membrane with both passive cooling and heat preservation functions in all weather conditions. Compared with Example 1, the only difference is that in step S3, the alumina fluid is 0.4286g and the alumina fluid content is 12.5% ​​of the thermoplastic polyurethane content. Other experimental parameters and conditions are basically the same as in Example 1, and will not be repeated here.

[0055] Example 6

[0056] This embodiment provides a method for preparing a wearable fiber membrane with both passive cooling and heat preservation functions in all weather conditions. Compared with Example 1, the only difference is that in step S3, the alumina fluid is 0.5294g and the alumina fluid content is 15% of the thermoplastic polyurethane content. Other experimental parameters and conditions are basically the same as in Example 1, and will not be repeated here.

[0057] Example 7

[0058] This embodiment provides a method for preparing a wearable fiber membrane with both passive cooling and heat preservation functions in all weather conditions. Compared with Example 1, the only difference is that in step S3, the alumina fluid is 0.75g and the alumina fluid content is 20% of the thermoplastic polyurethane content. Other experimental parameters and conditions are basically the same as in Example 1, and will not be repeated here.

[0059] Comparative Example 1 Comparative Example 1 provides a method for preparing a wearable fiber membrane with both passive cooling and heat preservation functions in all weather conditions. The only difference from Example 1 is that in step S4, no hollow structure design was performed, and the entire fiber membrane is a solid PU fiber. Other experimental parameters and conditions are basically the same as in Example 1, and will not be repeated here. The final fiber membrane is named PU fiber membrane.

[0060] Comparative Example 2 Comparative Example 2 provides a method for preparing a wearable fiber membrane with both passive cooling and heat preservation functions in all weather conditions. Compared to Example 1, the only difference is that in step S4, the core layer pushing speed is 0.1 mL / h, 0.2 mL / h, 0.4 mL / h, and 0.5 mL / h, respectively. Other experimental parameters and conditions are basically the same as in Example 1 and will not be repeated here. At different core layer pushing speeds, the pore size of the core layer varies. At pushing speeds of 0.1 mL / h and 0.2 mL / h, the pore size increases, allowing the fiber membrane to retain more static air. At pushing speeds of 0.4 mL / h and 0.5 mL / h, although the pore size also increases, adhesion occurs between fibers. This is because removing more glycerol / water requires more soaking time, which in turn affects the evaporation of the solvent in the fiber membrane itself, thus causing adhesion. A larger core layer pore size results in a thinner shell, thus offering weaker resistance to external cold air, macroscopically manifested as a lower heat preservation temperature.

[0061] Comparative Example 3 Comparative Example 3 provides a method for preparing a wearable fiber membrane with both passive cooling and heat preservation functions in all weather conditions. The only difference from Example 1 is that in step S3, the alumina fluid is replaced with alumina nanoparticles. Other experimental parameters and conditions are basically the same as in Example 1 and will not be repeated here. Because the alumina nanoparticles cannot be effectively dispersed, they agglomerate. This agglomeration prevents effective reflection and scattering of sunlight. Furthermore, the agglomerated alumina nanoparticles create more stress concentration points in the fiber membrane, leading to a decrease in the mechanical properties of the fiber membrane itself.

[0062] Comparative Example 4 Comparative Example 4 provides a method for preparing a wearable fiber membrane with both passive cooling and heat preservation functions in all weather conditions. The only difference from Example 1 is that the entire fiber membrane is a hollow fiber membrane constructed from thermoplastic polyurethane / alumina fluid, without a pure thermoplastic polyurethane solid fiber layer. Other experimental parameters and conditions are basically the same as in Example 1 and will not be repeated here. Because the alumina fluid chain has a large number of hydrophilic groups, the entire fiber membrane is hydrophilic. While this design can absorb moisture from the surface of human skin, it can also absorb water from the external air or rain, causing extreme discomfort to the human body.

[0063] Figure 1 A schematic diagram illustrating the preparation method of the wearable fiber membrane with both passive cooling and heat preservation functions provided in this embodiment of the invention; Figure 2The bar charts show the passive cooling of fiber membranes with different alumina fluid contents in the embodiments of the present invention. From left to right, they represent Embodiment 1, Embodiment 2, Embodiment 3, Embodiment 4, Embodiment 5, Embodiment 6, and Embodiment 7. It can be seen that when the alumina fluid content ranges from 0% to 10%, the fluidization of alumina nanoparticles effectively disperses them, increasing sunlight reflection and thus enhancing the radiative cooling effect. When the content exceeds 10%, even with fluidization, a large amount of alumina nanoparticles agglomerate, severely affecting the reflectivity of the fiber membrane. Although the overall radiative cooling performance improves, it still weakens the radiative cooling effect compared to 10%. Figure 3 The graph shows the solar reflectance variation curves of HPUA, HPU, and PU fiber membranes in the solar band in Embodiment 4 of the present invention. Compared with PU fiber membranes, it can be seen that the hollow structure design helps to increase the fiber diameter, and this increase promotes more reflection of sunlight. Furthermore, by adding an appropriate amount of alumina fluid to the shell of such hollow fibers, the overall reflectance of HPUA fiber membrane increases because alumina nanoparticles themselves have a reflective effect on sunlight. Figure 4 These are infrared thermal images of the HPUA fiber membrane and commercially available Cotton under outdoor conditions, as shown in Embodiment 4 of this invention. It can be seen that the structural design of the HPUA fiber membrane and the addition of alumina fluid contribute to temperature reduction during wear. Figure 5 The images shown are SEM images of the bilayer fiber membranes with different core layer pushing speeds obtained in Comparative Example 2 of this invention. It can be seen that as the pushing speed increases, the core layer pore size gradually increases and the shell layer thickness gradually decreases. Figure 6 The thermal conductivity variation curves of the bilayer fiber membranes with different core layer pushing speeds obtained in Comparative Example 2 of this invention show that the thermal conductivity first decreases and then increases with the increase of pushing speed. Before the pushing speed of 0.3 mL / h, the increase in the core layer pore size helps the fiber membrane to maintain static air and reduce thermal conductivity. After the pushing speed of 0.3 mL / h, the decrease in shell thickness affects the heat transfer of the fiber membrane against external environmental factors. At the same time, more glycerol / water in the core layer needs to be soaked for a longer time during the preparation process to remove the core layer. This affects the volatilization of organic solvents in the fiber membrane to a certain extent, resulting in more adhesion between fibers and the formation of thermal conduction channels. Therefore, the thermal conductivity will rebound after the pushing speed of 0.3 mL / h. Figure 7As shown in Example 2 of this invention, the HPUA fiber membrane and commercial Cotton exhibit excellent thermal insulation performance outdoors at night. It can be observed that in a winter nighttime outdoor environment, the HPUA fiber membrane effectively traps static air, resulting in a temperature approximately 2°C higher under the fiber membrane than the ambient temperature. ◦ C, demonstrating the excellent heat insulation effect of HPUA fiber membrane; It should be noted that the present invention is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments that have the same structure and perform the same effects as the technical concept within the scope of the present invention are included within the scope of the present invention. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of the present invention, are also included within the scope of the present invention.

Claims

1. A method for preparing a wearable fiber membrane with both passive cooling and heat preservation functions in all weather conditions, characterized in that, Includes the following steps: Step S1. Prepare a polyetheramine solution, then add γ-glycidyl etheroxypropyltrimethoxysilane to react and obtain a modified polyetheramine solution; Step S2. Alumina nanoparticles are mixed and reacted with a modified polyetheramine solution to obtain alumina fluid; Step S3. Dissolve thermoplastic polyurethane in a mixed solvent of N,N-dimethylformamide and tetrahydrofuran to prepare a thermoplastic polyurethane electrospinning solution; add alumina fluid to the thermoplastic polyurethane electrospinning solution to obtain a mixed electrospinning solution. Step S4. Using coaxial electrospinning technology, first spin a thermoplastic polyurethane electrospinning solution as the core layer, and then spin a mixed electrospinning solution as the shell layer to form a double-layer fiber membrane. Step S5. The double-layer fiber membrane is soaked in deionized water to remove the core layer, then soaked in tert-butanol / water solution and freeze-dried to maintain the hollow structure, thus obtaining a wearable fiber membrane with all-weather passive cooling and heat preservation functions.

2. The method for preparing the wearable fiber membrane with both passive cooling and heat preservation functions in all weather conditions according to claim 1, characterized in that, In step S1, the mass-to-volume ratio of the polyetheramine to methanol is 1:5 to 1:10 g / mL, the reaction temperature is 40 to 60°C, and the reaction time is 20 to 28 hours.

3. The method for preparing the wearable fiber membrane with all-weather passive cooling and heat preservation functions according to claim 2, characterized in that, The mass ratio of γ-glycidoxypropyltrimethoxysilane to polyetheramine is 1:5 to 1:

10.

4. The method for preparing the wearable fiber membrane with both passive cooling and heat preservation functions in all weather conditions according to claim 1, characterized in that, In step S2, the amount of alumina nanoparticles added is 5-15% of the total mass of the modified polyetheramine.

5. The method for preparing the wearable fiber membrane with all-weather passive cooling and heat preservation functions according to claim 1, characterized in that, In step S3, the volume ratio of N,N-dimethylformamide to tetrahydrofuran is 1:1 to 1:2, and the concentration of the thermoplastic polyurethane electrospinning solution is 25 to 35 wt%.

6. The method for preparing the wearable fiber membrane with both passive cooling and heat preservation functions in all weather conditions according to claim 5, characterized in that, In step S4, the core layer of the coaxial electrospinning is a mixed solution of glycerol and water, with a mass ratio of glycerol to water of 9:1 to 9.5:0.5, and the shell layer is a thermoplastic polyurethane electrospinning solution containing alumina fluid, wherein the alumina fluid accounts for 5 to 15% of the mass of the thermoplastic polyurethane.

7. The method for preparing the wearable fiber membrane with all-weather passive cooling and heat preservation functions according to claim 6, characterized in that, The process parameters for coaxial electrospinning are as follows: core layer advance speed 0.5~1.5 mL / h, shell layer advance speed 0.8~1.2 mL / h, spinning voltage 10~20 kV, and receiving distance 10~20 cm.

8. The method for preparing the wearable fiber membrane with all-weather passive cooling and heat preservation functions according to claim 1, characterized in that, In step S5, the deionized water soaking time is 20-28 hours, the volume concentration of tert-butanol / water solution is 20-30%, and the soaking time is 2-6 hours.

9. A wearable fiber membrane with both passive cooling and heat preservation functions in all weather conditions, characterized in that, Prepared by the method according to any one of claims 1-8.

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