Fiber membrane with bionic radiation refrigeration and health monitoring functions and preparation method thereof

Abstract

The invention provides a fiber membrane with bionic radiation refrigeration and health monitoring functions and a preparation method thereof, and belongs to the technical field of textile, PVDF-HFP is dissolved in an organic solvent, and a PVDF-HFP fiber layer is obtained through electrostatic spinning; cA is dissolved in an organic solvent, a CA fiber layer is formed on the PVDF-HFP fiber layer through electrostatic spinning, and a PVDF-HFP / CA composite fiber membrane is obtained; chitosan quaternary ammonium salt reacts with NPES-20 to obtain CSfs, the CSfs and Al2O3 are mixed and dispersed to obtain a CSfs-coated Al2O3 functional coating, the CSfs-coated Al2O3 functional coating is sprayed to the surface of a CA fiber layer of the composite fiber membrane, and the fiber membrane with bionic radiation refrigeration and health monitoring functions is obtained after drying. The technical bottleneck that it is difficult to collaboratively integrate radiation refrigeration and health monitoring functions is solved, and the multifunctional intelligent material integrating efficient cooling, precise monitoring, flexibility and breathability is successfully prepared.

Description

Technical Field

[0001] This invention relates to the fields of intelligent thermal management and wearable electronics, specifically to a fiber membrane that combines biomimetic radiation cooling and health monitoring functions, and its preparation method. Background Technology

[0002] Passive daytime radiative cooling (PDRC) technology provides an ideal solution for achieving zero-energy cooling by efficiently reflecting sunlight and radiating human body heat into space through an 8-14μm atmospheric window. Meanwhile, wearable health monitoring technology, as a core direction in the development of smart textiles, is continuously driving the deep integration of flexible electronics and fabric systems. Integrating radiative cooling functionality with physiological signal sensing capabilities into a single multifunctional fiber membrane can not only provide continuous thermal comfort for outdoor workers and other high-temperature exposed groups, but also achieve real-time safety monitoring, possessing significant application value and broad industrialization prospects.

[0003] However, achieving effective integration of these two functions still faces significant challenges. The core bottleneck lies in the material property mismatch and interface incompatibility between the high-performance radiative cooling layer and the highly sensitive sensing layer. On the one hand, to achieve excellent radiative cooling performance, high concentrations of inorganic functional particles (such as Al2O3 and TiO2) are typically introduced into the fiber structure to enhance solar reflectivity and mid-infrared emissivity. However, these particles are prone to agglomeration in the polymer matrix, leading to uneven dispersion, which in turn affects optical uniformity and may cause deterioration of fiber mechanical properties. Furthermore, traditional processing methods struggle to stably anchor particles on the hydrophobic fiber surface and in the three-dimensional porous network, making them prone to detachment during use and severely impacting the durability of the cooling effect. On the other hand, if the subsequently constructed sensing functional layer (such as a conductive polymer or ion-conductive coating) is directly applied to the surface of the cooling layer, it often causes blockage of the porous structure or obscures the active sites of the functional particles, significantly weakening solar reflectivity. Simultaneously, due to the weak interfacial bonding between the two functional layers, delamination or cracks are prone to occur under dynamic deformation conditions such as repeated stretching and bending, leading to unstable sensing signals or even failure. Therefore, existing technologies generally struggle to achieve synergistic optimization of cooling and sensing performance. Most research remains limited to simple lamination or physical blending strategies, lacking sufficient structural stability, functional integration, and long-term reliability, thus failing to meet the comprehensive requirements of comfort, durability, and multifunctional integration in actual wearable scenarios.

[0004] Chitosan and its derivatives have been widely used in textile finishing due to their excellent biocompatibility, film-forming properties, and abundant chemical modification sites. However, when traditional chitosan materials are used as functional coatings on synthetic fiber substrates, they often face problems such as insufficient mechanical strength, poor water resistance, and weak interfacial adhesion with hydrophobic polymers (such as PVDF-HFP and CA), which limit their in-depth application as multifunctional interlayers in high-performance smart fabrics. How to modify the molecular structure of chitosan to give it both excellent nanoparticle dispersion ability and strong interfacial adhesion properties, thereby firmly anchoring inorganic functional particles in the fiber network to maintain long-term radiative cooling performance, while also enabling it to self-assemble into continuous and stable conductive pathways to achieve highly sensitive and interference-resistant human motion signal detection, is a key scientific and technological challenge that urgently needs to be overcome in the field of multifunctional fiber materials.

[0005] In view of this, it is necessary to design a fiber membrane that combines biomimetic radiation cooling and health monitoring functions, as well as its preparation method, to solve the above problems. Summary of the Invention

[0006] In view of the technical problems existing in the background art, this application provides a fiber membrane with both biomimetic radiation cooling and health monitoring functions and its preparation method, aiming to solve the technical problem that it is difficult to stably integrate a high-performance radiation cooling layer and a high-sensitivity sensing layer, and that their performances are mutually restrictive.

[0007] In a first aspect, this application provides a method for preparing a fiber membrane that combines biomimetic radiation cooling and health monitoring functions, comprising the following steps: S1. Dissolve PVDF-HFP in an organic solvent to prepare a PVDF-HFP electrospinning solution, and obtain a PVDF-HFP fiber layer by electrospinning; S2. Dissolve CA in an organic solvent to prepare a CA electrospinning solution, and then electrospin the solution to form a CA fiber layer on the PVDF-HFP fiber layer to obtain a PVDF-HFP / CA composite fiber membrane. S3. Reaction of chitosan quaternary ammonium salt with NPES-20 to obtain CSfs, and mixing and dispersing the CSfs with Al2O3 in deionized water to obtain CSfs@Al2O3 functional coating; S4. The CSfs@Al2O3 functional coating is sprayed onto the surface of the CA fiber layer of the PVDF-HFP / CA composite fiber membrane. After drying, a fiber membrane with both biomimetic radiation cooling and health monitoring functions is obtained.

[0008] As a further improvement of this application, in step S1, the organic solvent is prepared by mixing acetone and N,N-dimethylformamide in a volume ratio of (2:8) to (3:7).

[0009] As a further improvement of this application, the concentration of the PVDF-HFP electrospinning solution is 10~14wt%.

[0010] As a further improvement of this application, in step S2, the organic solvent is prepared by mixing acetone and N,N-dimethylformamide in a volume ratio of (7:3) to (8:2).

[0011] As a further improvement of this application, the concentration of the CA electrospinning solution is 10~14wt%.

[0012] As a further improvement of this application, in step S3, the mass ratio of the chitosan quaternary ammonium salt to NPES-20 is 1:(1~3).

[0013] As a further improvement of this application, in step S3, the total solid content of the CSfs@Al2O3 functional coating is 10~15wt%.

[0014] As a further improvement of this application, the mass of Al2O3 accounts for 2.5 to 50% of the total solid content of the CSfs@Al2O3 functional coating.

[0015] As a further improvement to this application, in step S4, the spraying amount is controlled to be 0.5~1.5mL / 16cm. 2 The drying temperature is 30~60℃.

[0016] Secondly, this application provides a fiber membrane that combines biomimetic radiation cooling and health monitoring functions, which is prepared by the method described in the first aspect for preparing a fiber membrane that combines biomimetic radiation cooling and health monitoring functions.

[0017] The beneficial effects of this application are as follows: This application provides a fiber membrane with both biomimetic radiative cooling and health monitoring functions, and its preparation method. The method involves dissolving PVDF-HFP in an organic solvent to prepare a PVDF-HFP electrospinning solution, followed by electrospinning to obtain a PVDF-HFP fiber layer. Then, CA is dissolved in an organic solvent to prepare a CA electrospinning solution, which is then electrospinned onto the PVDF-HFP fiber layer to form a CA fiber layer, resulting in a PVDF-HFP / CA composite fiber membrane. Chitosan quaternary ammonium salt is reacted with NPES-20 to obtain CSfs, which are then mixed and dispersed with Al2O3 in deionized water to obtain a CSfs@Al2O3 functional coating. This CSfs@Al2O3 functional coating is sprayed onto the surface of the CA fiber layer of the PVDF-HFP / CA composite fiber membrane, and after drying, a fiber membrane with both biomimetic radiative cooling and health monitoring functions is obtained. This fiber membrane and its preparation method ingeniously solve the technical bottleneck of the difficulty in synergistically integrating radiative cooling and health monitoring functions, successfully preparing a multifunctional smart material that integrates efficient cooling, precise monitoring, and flexibility.

[0018] This application constructs a PVDF-HFP / CA composite fiber membrane with good mechanical support through sequential electrospinning. Furthermore, utilizing the hydrophilic / hydrophobic segment properties of chitosan flakes (CSfs), Al2O3 is stably dispersed in aqueous solution through charge interactions. After spraying and drying, chitosan molecular chains firmly "anchor" Al2O3 to the fiber surface and between fibers through hydrogen bonding and interfacial interactions, successfully constructing an optical structure mimicking the vesicular cells of ice plant. This structure endows the fiber membrane with a solar reflectivity of up to 92% and a high atmospheric window emissivity, achieving a significant radiative cooling effect. Simultaneously, CSfs increase the ionic conductivity of the fiber membrane and suppress charge dissipation, giving it superior triboelectric properties, enabling continuous and accurate monitoring of human movement.

[0019] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of this application, the accompanying drawings used in this application will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without any creative effort.

[0021] Figure 1A schematic diagram illustrating the preparation method of the fiber membrane with both biomimetic radiation cooling and health monitoring functions provided in the embodiments of this application; Figure 2 An optical photograph of Ice Plant and a schematic diagram of its vesicular cell structure; Figure 3 A schematic diagram of the structure of a fiber membrane that combines biomimetic radiation cooling and health monitoring functions, provided in an embodiment of this application. Figure 4 These are scanning electron microscope images of the PC fiber membrane, PCCA fiber membrane, and PCC fiber membrane obtained in Example 1 of this application and Comparative Example 1. Figure 5 The bar chart shows the radiation cooling effect of the fiber membranes obtained in Examples 1-8 and Comparative Example 1 of this application. Figure 6 Line graphs showing the solar reflectance and mid-infrared emissivity of the PC fiber membrane, PCCA fiber membrane, and PCC fiber membrane obtained in Example 1 of this application and Comparative Example 1; Figure 7 Line graphs showing the triboelectric output voltage and time relationship of the PC fiber membrane, PCCA fiber membrane obtained in Example 1 of this application, and the PCC fiber membrane obtained in Comparative Example 1. Figure 8 The signal diagrams of the fiber membrane with both biomimetic radiation cooling and health monitoring functions provided in Embodiment 1 of this application during walking, running and jumping. Figure 9 The fiber membrane with both biomimetic radiative cooling and health monitoring functions provided in Embodiment 1 of this application is shown in an outdoor environment, simultaneously performing radiative cooling and motion monitoring. Explanation of reference numerals in the attached figures: 1. PVDF-HFP fiber layer; 2. CA fiber layer; 3. CSfs@Al2O3 functional coating. Detailed Implementation

[0022] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0024] In the description of the embodiments of this application, 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 application, "multiple" means two or more, unless otherwise explicitly defined.

[0025] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout 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 herein can be combined with other embodiments.

[0026] The integration of passive daytime radiative cooling and health monitoring is of great significance to wearable technology, but it faces severe challenges. The core bottleneck lies in the material mismatch and interface incompatibility between the cooling layer and the sensing layer. This is mainly manifested in the tendency of inorganic functional particles to agglomerate and detach, while the sensing layer can clog pores and weaken cooling, and weak interlayer bonding leads to structural instability. Existing technologies, such as lamination or physical blending, can achieve single functions, but they generally suffer from poor durability and mutual performance constraints, failing to meet the comprehensive requirements of multifunctional integration in practical applications.

[0027] To address the technical problems of functional inhibition, poor structural stability, and low long-term reliability caused by material property mismatch and interface incompatibility between the radiative cooling layer and the sensing layer, this application provides a fiber membrane with both biomimetic radiative cooling and health monitoring functions, and its preparation method. Specifically, by utilizing modified chitosan CSfs with both hydrophilic and hydrophobic segments as a multifunctional interface layer, inorganic functional particles Al2O3 are firmly anchored to the fiber network to construct a biomimetic optical structure, while simultaneously forming a stable conductive path. This achieves efficient and durable passive radiative cooling and highly sensitive self-driven health monitoring synergistically within a single fiber membrane, ensuring structural stability and functional reliability of the device under dynamic deformation.

[0028] Please see Figure 1 In a first aspect, embodiments of this application provide a method for preparing a fiber membrane that combines biomimetic radiation cooling and health monitoring functions, comprising the following steps: S1. Dissolve PVDF-HFP in an organic solvent to prepare a PVDF-HFP electrospinning solution, and obtain PVDF-HFP fiber layer 1 by electrospinning; S2. Dissolve CA in an organic solvent to prepare a CA electrospinning solution, and then electrospin the solution onto the PVDF-HFP fiber layer 1 to form a CA fiber layer 2, thereby obtaining a PVDF-HFP / CA composite fiber membrane. S3. Chitosan quaternary ammonium salt was reacted with NPES-20 to obtain CSfs. CSfs and Al2O3 were mixed and dispersed in deionized water to obtain CSfs@Al2O3 functional coating 3. S4. Spray CSfs@Al2O3 functional coating 3 onto the surface of CA fiber layer 2 of PVDF-HFP / CA composite fiber membrane, and after drying, obtain a fiber membrane with both biomimetic radiation cooling and health monitoring functions.

[0029] In the technical solution of this application embodiment, a process combining electrospinning and spraying technology is adopted. First, a Janus structure base membrane composed of PVDF-HFP (polyvinylidene fluoride-hexafluoropropylene copolymer) and CA (cellulose acetate) is constructed by sequential electrospinning (i.e., PVDF-HFP / CA composite fiber membrane, hereinafter referred to as PC fiber membrane for ease of expression). Then, a chitosan quaternary ammonium salt solution grafted with NPES-20 (nonylphenol polyoxyethylene ether (20) sodium sulfate) (chitosan fluid (CSfs)) is mixed with alumina nanoparticles (Al2O3) to form a stable and dispersed functional coating by utilizing charge interaction, and it is uniformly sprayed onto the surface of the Janus base membrane. After drying, the chitosan fluid forms a film and solidifies Al2O3 in the fiber network to construct a multi-scale microstructure that mimics the vesicular cells of the ice plant epidermis, i.e., a fiber membrane with both biomimetic radiation cooling and health monitoring functions (hereinafter referred to as PCCA fiber membrane for ease of expression). This structure not only endows the fiber membrane with a solar reflectivity of up to 92% and efficient thermal radiation emission capability in the atmospheric window band, achieving a passive radiative cooling effect 9.86℃ lower than the ambient temperature, but also possesses excellent triboelectric power generation characteristics, enabling continuous and accurate monitoring of human movement and triggering distress signals under specific conditions. It successfully integrates radiative cooling and physiological state sensing functions, effectively overcoming the contradiction between functional coupling and structural stability in the practical application of multifunctional flexible electronic fabrics.

[0030] Furthermore, in some embodiments, in step S1, the organic solvent is prepared by mixing acetone and N,N-dimethylformamide in a volume ratio of (2:8) to (3:7).

[0031] In the technical solution of this application embodiment, a solvent system of acetone (AC) and N,N-dimethylformamide (DMF) is selected during the electrospinning process. The synergistic effect of the two solvents is used to regulate the physicochemical properties of the spinning solution and the fiber forming process. The highly volatile acetone ensures that the jet evaporates rapidly after leaving the nozzle, promoting rapid fiber solidification and forming. The low-volatility DMF effectively dissolves the polymer and maintains the conductivity of the solution, while delaying the complete drying of the jet, giving the polymer chain segments sufficient time for stretching and orientation. This avoids nozzle clogging caused by premature jet solidification and ultimately helps to form continuous fibers with uniform diameter, smooth surface, and excellent mechanical properties.

[0032] Furthermore, in some embodiments, the concentration of the PVDF-HFP electrospinning solution is 10~14wt%.

[0033] In the technical solution of this application embodiment, the concentration of the PVDF-HFP electrospinning solution is controlled within the range of 10~14wt%, which can precisely regulate the degree of polymer chain entanglement to achieve stable and continuous fiber formation. When the concentration is below this range, the polymer chain entanglement is insufficient, and droplets or beaded structures are easily formed under the electric field, making it impossible to form continuous fibers; while when the concentration is too high, the solution viscosity is too high, making it difficult for the electric field to effectively overcome surface tension and viscous resistance, resulting in spraying difficulties or even clogging of the nozzle. Specifically, the positive voltage of electrospinning is 8~10kV, the negative voltage is 2~6kV, and the feed rate is 1~1.5mL / h.

[0034] Furthermore, in some embodiments, in step S2, the organic solvent is prepared by mixing acetone and N,N-dimethylformamide in a volume ratio of (7:3) to (8:2).

[0035] In the technical solution of this application embodiment, CA has better solubility in acetone than PVDF-HFP, so increasing the proportion of acetone can ensure its full dissolution. At the same time, the high proportion of acetone, as a highly volatile solvent, allows the CA solution jet to solidify rapidly upon contact with the underlying PVDF-HFP fiber membrane, effectively preventing excessive erosion or dissolution of the formed fiber layer by the solvent and ensuring a clear interface of the double-layer structure. The retained DMF continues to maintain the appropriate viscosity and conductivity of the solution, ensuring the stability of the spinning process, and ultimately achieving uniform and controllable deposition of the CA fiber layer 2 on the PVDF-HFP layer.

[0036] Furthermore, in some embodiments, the concentration of the CA electrospinning solution is 10-14 wt%.

[0037] In the technical solution of this application embodiment, the concentration range provides the optimal entanglement density for the CA polymer chains, effectively avoiding the "beading" effect and fiber breakage caused by excessively low concentration, while preventing problems such as excessive solution viscosity, spraying difficulties, and uneven fiber diameter caused by excessively high concentration. By precisely controlling this concentration, a CA fiber layer with suitable pore structure and good mechanical properties can be prepared. This not only provides an ideal hydrophilic interface for the firm adhesion of subsequent functional coatings, but also ensures the flexibility and air permeability of the entire composite fiber membrane, which is the key structural basis for realizing multifunctional integrated design. Specifically, the positive voltage of electrospinning is 10~15kV, the negative voltage is 1~5kV, and the feed rate is 1~1.5mL / h.

[0038] Furthermore, in some embodiments, in step S3, the mass ratio of chitosan quaternary ammonium salt to NPES-20 is 1:(1~3).

[0039] In the technical solution of this application embodiment, a suitable mass ratio ensures that sufficient NPES-20 molecules can react with the active sites on the chitosan quaternary ammonium salt, simultaneously introducing a large number of hydrophobic segments and hydrophilic groups into the molecular structure. This high degree of modification significantly enhances the dispersion and stabilization ability of CSfs on Al2O3 nanoparticles, preventing their aggregation; it also improves the interfacial adhesion properties of CSfs, enabling them to firmly bind the hydrophilic CA fiber layer and the hydrophobic Al2O3 particles simultaneously, thereby improving the structural stability and functional durability of the final fiber membrane. Specifically, chitosan quaternary ammonium salt and NPES-20 are dissolved in deionized water, and the reaction is carried out at room temperature with stirring for no less than 24 hours. After dialyzing the mixed solution, it is dried to obtain CSfs.

[0040] Furthermore, in some embodiments, in step S3, the total solids content of the CSfs@Al2O3 functional coating 3 is 10-15%.

[0041] In the technical solution of this application embodiment, the appropriate total solids content ensures that the coating contains a sufficiently high concentration of CSfs and Al2O3 particles, which can quickly form a dense and continuous functional coating after spraying, thereby maximizing the radiative cooling efficiency and ensuring a stable sensing signal. At the same time, the coating at this solids content has moderate viscosity and rheological properties, which not only ensures good atomization effect and spray uniformity, but also effectively avoids problems such as nozzle clogging, poor coating leveling and fiber membrane pore blockage caused by excessive solids content.

[0042] Furthermore, in some embodiments, the mass of Al2O3 accounts for 2.5 to 50% of the total solid content of CSfs@Al2O3 functional coating 3.

[0043] In the technical solution of this application embodiment, a suitable Al2O3 content helps to ensure the continuity of the CSfs matrix and the ion conduction pathway, thereby ensuring the sensitivity of the health monitoring function and the flexibility of the fiber membrane; at the same time, it helps to maximize the solar reflectivity and infrared emissivity of the functional coating to achieve the ultimate radiative cooling effect. The Al2O3 content range allows for dynamic trade-offs and optimization between the two core functions of "efficient cooling" and "highly sensitive sensing" by precisely controlling the Al2O3 loading according to actual application needs, thereby preparing customized multifunctional fiber membranes that meet the needs of different scenarios.

[0044] Furthermore, in some embodiments, in step S4, the spraying amount is controlled to be 0.5~1.5mL / 16cm. 2 The drying temperature is 30~60℃.

[0045] In the technical solution of this application embodiment, an appropriate coating amount ensures that the CSfs@Al2O3 functional coating 3 can fully cover the CA fiber layer 2 to form a continuous cooling and sensing network, while avoiding pore blockage, fiber hardening, and functional redundancy caused by excessive coating. A mild drying temperature of 30~60°C is sufficient to effectively remove moisture and promote the rearrangement of CSfs molecular chains to form a strong interfacial bond, while preventing deformation of the CA fiber layer 2 or degradation of CSfs molecules due to excessive temperature. The synergistic effect of these two parameters ultimately ensures the uniform and firm deposition of the functional coating on the porous fiber substrate, which is a key process control for achieving a highly efficient, stable, and flexible multifunctional fiber membrane.

[0046] Please see Figure 3 Secondly, embodiments of this application provide a fiber membrane that combines biomimetic radiation cooling and health monitoring functions, which is prepared by the method described in the first aspect for preparing a fiber membrane that combines biomimetic radiation cooling and health monitoring functions.

[0047] In the technical solution of this application embodiment, a biomimetic multifunctional fiber membrane was successfully developed through material innovation and process synergistic design, realizing the deep coupling and synergistic enhancement of radiation cooling and health monitoring functions, while also possessing excellent air permeability, flexibility and mechanical durability, which is of great significance for promoting the development of the next generation of intelligent thermal management textiles.

[0048] The following are some specific embodiments. It should be noted that the embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. 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 whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0049] Example 1 This application provides a method for preparing a fiber membrane that combines biomimetic radiation cooling and health monitoring functions, including the following steps: S1. Dissolve 1.2g of PVDF-HFP in a mixed solvent of 8.8g of AC and DMF (volume ratio 3:7) to prepare a PVDF-HFP electrospinning solution with a concentration of 12wt%. Electrospinning was carried out for 6 hours using a 20G needle under the conditions of positive voltage 8kV, negative voltage 4kV, feed speed 1.5mL / h, and receiving distance 10cm to obtain PVDF-HFP fiber layer 1. S2. Dissolve 1.2g CA in a mixed solvent of 8.8g AC and DMF (volume ratio 7:3) to prepare a CA electrospinning solution with a concentration of 12wt%. Using a 20G needle, electrospinning is performed on PVDF-HFP fiber layer 1 under the conditions of positive voltage 13kV, negative voltage 3kV, feed speed 1mL / h, and receiving distance 15cm to form CA fiber layer 2 and obtain PC fiber membrane. S3. Dissolve 1g of chitosan quaternary ammonium salt (purchased from Zhejiang Jinke Pharmaceutical Co., Ltd.) and 3g of NPES-20 in 40ml of deionized water, stir magnetically at room temperature for 24 hours, dialyze the mixture for 5 days, and then dry it at 45℃ for 60 hours to obtain CSfs. Take 0.27g of CSfs and 0.03g of Al2O3, mix them with 1.7g of deionized water, stir evenly, and obtain CSfs@Al2O3 functional coating 3 with a total solid content of 15%, wherein the Al2O3 content is 10% of the total solid content of CSfs@Al2O3 functional coating 3. S4. Using a sprayer, evenly spray 1 ml of CSfs@Al2O3 functional coating 3 onto a 4×4 cm (16 cm) area. 2 The surface of the CA fiber layer 2 of the PC fiber membrane is dried at 45°C to obtain the PCCA fiber membrane.

[0050] Example 2 This embodiment provides a method for preparing a fiber membrane that combines biomimetic radiation cooling and health monitoring functions. Compared with Example 1, the only difference is that in step S3, CSfs is 0.2925g, Al2O3 is 0.0075g, and the Al2O3 content is 2.5% of the total solid content of CSfs@Al2O3 functional coating 3. Other experimental parameters and conditions are basically the same as in Example 1, and will not be repeated here.

[0051] Example 3 This embodiment provides a method for preparing a fiber membrane that combines biomimetic radiation cooling and health monitoring functions. Compared with Example 1, the only difference is that in step S3, CSfs is 0.285g, Al2O3 is 0.015g, and the Al2O3 content is 5% of the total solid content of CSfs@Al2O3 functional coating 3. Other experimental parameters and conditions are basically the same as in Example 1, and will not be repeated here.

[0052] Example 4 This embodiment provides a method for preparing a fiber membrane that combines biomimetic radiation cooling and health monitoring functions. Compared with Example 1, the only difference is that in step S3, CSfs is 0.2775g, Al2O3 is 0.0225g, and the Al2O3 content is 7.5% of the total solid content of CSfs@Al2O3 functional coating 3. Other experimental parameters and conditions are basically the same as in Example 1, and will not be repeated here.

[0053] Example 5 This embodiment provides a method for preparing a fiber membrane that combines biomimetic radiation cooling and health monitoring functions. Compared with Example 1, the only difference is that in step S3, CSfs is 0.24g, Al2O3 is 0.06g, and the Al2O3 content is 20% of the total solid content of CSfs@Al2O3 functional coating 3. Other experimental parameters and conditions are basically the same as in Example 1, and will not be repeated here.

[0054] Example 6 This embodiment provides a method for preparing a fiber membrane that combines biomimetic radiation cooling and health monitoring functions. Compared with Example 1, the only difference is that in step S3, CSfs is 0.21g, Al2O3 is 0.09g, and the Al2O3 content is 30% of the total solid content of CSfs@Al2O3 functional coating 3. Other experimental parameters and conditions are basically the same as in Example 1, and will not be repeated here.

[0055] Example 7 This embodiment provides a method for preparing a fiber membrane that combines biomimetic radiation cooling and health monitoring functions. Compared with Example 1, the only difference is that in step S3, CSfs is 0.18g, Al2O3 is 0.12g, and the Al2O3 content is 40% of the total solid content of CSfs@Al2O3 functional coating 3. Other experimental parameters and conditions are basically the same as in Example 1, and will not be repeated here.

[0056] Example 8 This embodiment provides a method for preparing a fiber membrane that combines biomimetic radiation cooling and health monitoring functions. Compared with Example 1, the only difference is that in step S3, CSfs is 0.15g, Al2O3 is 0.15g, and the Al2O3 content is 50% of the total solid content of CSfs@Al2O3 functional coating 3. Other experimental parameters and conditions are basically the same as in Example 1, and will not be repeated here.

[0057] Comparative Example 1 Comparative Example 1 provides a method for preparing a fiber membrane that combines biomimetic radiation cooling and health monitoring functions. The only difference from Example 1 is that in step S3, CSfs is 0.3g and Al2O3 is not added. Other experimental parameters and conditions are basically the same as in Example 1, and will not be repeated here. The fiber membrane obtained is named PCC fiber membrane.

[0058] Comparative Example 2 Comparative Example 2 provides a method for preparing a fiber membrane with both biomimetic radiative cooling and health monitoring functions. The only difference from Example 1 is that in step S3, CSfs is 0.12g, Al2O3 is 0.18g, and the Al2O3 content is 60% of the total solid content of the CSfs@Al2O3 functional coating 3. Other experimental parameters and conditions are basically the same as in Example 1 and will not be repeated here. When the Al2O3 content is 60% or more of the total solid content of the CSfs@Al2O3 functional coating 3, a large amount of Al2O3 agglomerates on the fiber membrane, which cannot effectively reflect and scatter sunlight, severely affecting the radiative cooling performance.

[0059] Comparative Example 3 Comparative Example 3 provides a method for preparing a fiber membrane that combines biomimetic radiation cooling and health monitoring functions. The only difference from Example 1 is that in step S3, chitosan quaternary ammonium salt is directly mixed and dispersed with Al2O3 in deionized water. Other experimental parameters and conditions are basically the same as in Example 1 and will not be repeated here. Because the chitosan quaternary ammonium salt was not modified, Al2O3 could not be evenly dispersed in the solution, resulting in a lower strength for the pure chitosan quaternary ammonium salt membrane, which reduces the strength of the fiber membrane. Furthermore, the presence of numerous hydrophilic groups, such as amino groups, on NPES-20 reduces the adsorption of water by the fiber membrane to some extent, affecting its wearability.

[0060] Comparative Example 4 Comparative Example 4 provides a method for preparing a fiber membrane that combines biomimetic radiative cooling and health monitoring functions. The only difference from Example 1 is that PVDF-HFP and CA are blended to prepare an electrospinning solution for electrospinning. Other experimental parameters and conditions are basically the same as in Example 1 and will not be repeated here. The fiber membrane electrospun by the PVDF-HFP and CA mixture cannot achieve effective unidirectional moisture conduction, hindering the outward conduction of moisture when the human body wears the fiber membrane. Furthermore, excessive absorption of moisture from the air affects the CSfs membrane structure and sensing accuracy.

[0061] Figure 2 The image shows an optical photograph of ice plant and a schematic diagram of its vesicular cell structure. It can be seen that the vesicular cells of ice plant are composed of cell membranes enclosing cell fluid. This structure can increase the reflection of sunlight and reduce the epidermal temperature, thereby protecting ice plant from heat damage caused by sun exposure.

[0062] Figure 4 The images shown are scanning electron microscope (SEM) images of the PC fiber membrane, PCCA fiber membrane, and PCC fiber membrane obtained in Example 1 of this application and Comparative Example 1, where (i) is the PC fiber membrane, (ii) is the PCC fiber membrane, and (iii) is the PCCA fiber membrane. It can be seen that the PCCA fiber membrane undergoes self-thermal cross-linking after dehydration by CSfs@Al2O3 aqueous solution, which makes Al2O3 uniformly dispersed and fixed on the fiber membrane, reduces the detachment of nanoparticles, and successfully constructs the optical structure of imitation ice plant vesicle cells.

[0063] Figure 5 The bar charts show the radiative cooling effects of the fiber membranes obtained in Examples 1-8 and Comparative Example 1 of this application. From left to right, they represent Comparative Example 1, Example 2, Example 3, Example 4, Example 1, Example 5, Example 6, Example 7, and Example 8, respectively. It can be seen that as the Al2O3 content increases from 0% to 10%, the uniform dispersion of Al2O3 on the fibers by CSfs increases the solar reflection of the fiber membrane, thus improving the radiative cooling effect. When the content exceeds 10%, Al2O3 undergoes significant aggregation. This aggregation severely affects the solar reflectivity of the fiber membrane. Although the overall radiative cooling performance improves, it still weakens the radiative cooling effect compared to 10%.

[0064] Figure 6Line graphs showing the solar reflectance and mid-infrared emissivity of the PC fiber membrane, PCCA fiber membrane, and PCC fiber membrane obtained in Example 1 and Comparative Example 1, respectively, show that the solar reflectance of the PCC fabric increased by approximately 5.1%, while that of the PCCA fabric increased by approximately 11%. According to Kirchhoff's law, the emissivity of the PCC fabric is approximately 20% higher than that of the PC fabric within the atmospheric window. This is due to the coordinated vibrations of the stretching vibrations of SO, CO, and COC bonds in the CSfs membrane and the CF bonds in the PVDF-HFP membrane, as well as the interactions of ion pairs. These vibrations occur in the wavelength range of 7–14 μm. Compared to the PCC fabric, the emissivity of the PCCA fabric is further increased by approximately 20%. This is because the stretching vibrations of the Al-O bonds in the Al2O3 nanoparticles generate a strong absorption peak in the wavelength range of 11.1–20 μm, thereby increasing the emissivity within the atmospheric window.

[0065] Figure 7 The graphs show the relationship between the output voltage and time of triboelectric generation for the PC fiber membrane, PCCA fiber membrane, and PCC fiber membrane obtained in Example 1 and Comparative Example 1, respectively. It can be seen that the CSfs membrane between the fibers effectively increases the conductive path inside the fiber membrane, enabling more charges generated by contact separation to be collected and conducted, thereby increasing the output voltage.

[0066] Figure 8 This is a signal diagram of the fiber membrane with biomimetic radiative cooling and health monitoring functions provided in Embodiment 1 of this application during movement, where walking, running, and jumping are shown from left to right. It can be seen that different actions can be effectively identified by varying the output voltage and waveform width of the different action signals.

[0067] Figure 9 The image shows the fiber membrane with biomimetic radiative cooling and health monitoring functions provided in Embodiment 1 of this application performing radiative cooling and motion monitoring simultaneously in an outdoor environment. It can be seen that in an outdoor environment, the fiber membrane can effectively perform radiative cooling. Although the output voltage will be slightly reduced, it can still achieve stable signal output and recognition of knee movements.

[0068] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. 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 this application, are also included in the scope of this application.

Claims

1. A method for preparing a fiber membrane that combines biomimetic radiation cooling and health monitoring functions, characterized in that, Includes the following steps: S1. Dissolve PVDF-HFP in an organic solvent to prepare a PVDF-HFP electrospinning solution, and obtain a PVDF-HFP fiber layer by electrospinning; S2. Dissolve CA in an organic solvent to prepare a CA electrospinning solution, and then electrospin the solution to form a CA fiber layer on the PVDF-HFP fiber layer to obtain a PVDF-HFP / CA composite fiber membrane. S3. Reaction of chitosan quaternary ammonium salt with NPES-20 to obtain CSfs, and mixing and dispersing the CSfs with Al2O3 in deionized water to obtain CSfs@Al2O3 functional coating; S4. The CSfs@Al2O3 functional coating is sprayed onto the surface of the CA fiber layer of the PVDF-HFP / CA composite fiber membrane. After drying, a fiber membrane with both biomimetic radiation cooling and health monitoring functions is obtained.

2. The method for preparing the fiber membrane with both biomimetic radiation cooling and health monitoring functions according to claim 1, characterized in that, In step S1, the organic solvent is prepared by mixing acetone and N,N-dimethylformamide in a volume ratio of (2:8) to (3:7).

3. The method for preparing a fiber membrane with both biomimetic radiation cooling and health monitoring functions according to claim 2, characterized in that, The concentration of the PVDF-HFP electrospinning solution is 10~14wt%.

4. The method for preparing a fiber membrane with both biomimetic radiation cooling and health monitoring functions according to claim 1, characterized in that, In step S2, the organic solvent is prepared by mixing acetone and N,N-dimethylformamide in a volume ratio of (7:3) to (8:2).

5. The method for preparing a fiber membrane with both biomimetic radiation cooling and health monitoring functions according to claim 4, characterized in that, The concentration of the CA electrospinning solution is 10~14wt%.

6. The method for preparing a fiber membrane with both biomimetic radiation cooling and health monitoring functions according to claim 1, characterized in that, In step S3, the mass ratio of the chitosan quaternary ammonium salt to NPES-20 is 1:(1~3).

7. The method for preparing a fiber membrane with both biomimetic radiation cooling and health monitoring functions according to claim 1, characterized in that, In step S3, the total solids content of the CSfs@Al2O3 functional coating is 10~15wt%.

8. The method for preparing a fiber membrane with both biomimetic radiation cooling and health monitoring functions according to claim 7, characterized in that, The mass of Al2O3 accounts for 2.5-50% of the total solid content of the CSfs@Al2O3 functional coating.

9. The method for preparing a fiber membrane with both biomimetic radiation cooling and health monitoring functions according to claim 1, characterized in that, In step S4, the spraying amount is controlled to be 0.5~1.5mL / 16cm. 2 The drying temperature is 30~60℃.

10. A fiber membrane that combines biomimetic radiative cooling and health monitoring functions, characterized in that, The fiber membrane with both biomimetic radiation cooling and health monitoring functions is prepared by the method described in any one of claims 1-9.

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