Radiation-reducing color nanofiber film with multi-layer structure and method for preparing the same
By combining electrospinning and electrospraying to prepare multi-layered radiation-cooling colored nanofiber membranes, the problems of heat release and monotonous application of existing radiation-cooling materials are solved, and the effects of multi-color and high-efficiency radiation cooling are achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ZHEJIANG SCI-TECH UNIV
- Filing Date
- 2023-09-11
- Publication Date
- 2026-06-12
AI Technical Summary
Existing radiative cooling materials release heat while achieving cooling, and most of them are white, limiting their application scenarios. Their manufacturing methods are cumbersome and costly, making them unsuitable for large-scale applications.
A multi-layered radiation-cooled colored nanofiber membrane was prepared by combining electrospinning and electrospraying. Inorganic infrared reflective pigments were used to replace ordinary dyes or pigments to form colorful nanofiber membranes.
It achieves multi-color radiative cooling effect, reduces the impact of sunlight reflectivity, has superior radiative cooling performance, and broadens application scenarios.
Smart Images
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Abstract
Description
Technical Field
[0001] This invention relates to the field of materials, and in particular to a radiation-cooled colored nanofiber membrane with a multilayer structure and its preparation method. Background Technology
[0002] Most cooling materials release a significant amount of heat while achieving their cooling function, creating a thermal cycle. As atmospheric temperatures continue to rise, the demand for cooling materials is increasing. In line with the principles of green development, there is an urgent need for a sustainable, green energy-based cooling material. The principle of radiative cooling lies in the material's near 100% reflectivity in the solar wavelength range (0.3-2.5μm) to reduce heat input. Secondly, the material needs high emissivity in the atmospheric window (8-13μm) to radiate its heat into outer space. When the energy radiated by the material exceeds the energy absorbed, a cooling effect is achieved. The advantage of radiative cooling is that it utilizes the material's inherent optical properties, eliminating the generation of heat during the cooling process.
[0003] Recently, many researchers have used photonic crystal structures or biomimetic structures to fabricate radiation-cooled devices. However, these methods are cumbersome and costly, making them unsuitable for large-scale applications. Furthermore, most existing radiation-cooled devices are predominantly white to maximize material reflectivity, resulting in a monotonous appearance and limiting their application scenarios. Therefore, this invention aims to prepare multi-colored radiation-cooled thin films using a simple method. Summary of the Invention
[0004] The purpose of this invention is to provide a radiation-cooled colored nanofiber membrane with a multi-layer structure. This nanofiber has a multi-layer structure, good cooling effect, can be used for outdoor work for a long time, and is easy to prepare.
[0005] The technical solution adopted by this invention to solve its technical problem is:
[0006] A method for preparing a radiation-cooled colored nanofiber membrane with a multilayer structure, wherein the fiber membrane comprises three layers: a bottom nanofiber membrane, a middle layer of nanoparticles, and a surface colored nanofiber membrane.
[0007] The method includes the following steps:
[0008] S1. The polymer is dispersed in an organic solvent and heated and stirred for several hours to obtain a TPU spinning solution; the spinning solution is electrospun to obtain the underlying nanofiber membrane.
[0009] S2. Disperse the polymer in an organic solvent, with a polymer content of 15-20% by mass. After heating and stirring for several hours, obtain a TPU spray solution. Electrostatically spray the TPU onto the nanofiber membrane obtained in S1 to obtain nanoparticles in the intermediate layer. S3. Add the polymer and inorganic infrared reflective pigment to the organic solvent and stir for several hours to obtain a colored spinning solution. Continue spinning on the intermediate layer obtained in S2 to form a colored nanofiber membrane on its surface, thus obtaining a radiation-cooled colored nanofiber membrane with a multilayer structure.
[0010] This invention combines electrospinning and electrospraying, and adds near-infrared reflective pigments to obtain radiation-cooling films of different colors. The preparation method of this invention is simple, and the multi-layered structure gives the film a better cooling effect. Moreover, the film presents multiple colors, which broadens the application scenarios.
[0011] Preferably, the polymer is one or both of polyurethane and polyvinylidene fluoride.
[0012] Preferably, the organic solvent is one or more of N,N-dimethylformamide, acetone, or tetrahydrofuran.
[0013] Preferably, the inorganic infrared reflective pigment is one or more of titanium chromium yellow, titanium chromium brown, cobalt green, and titanium nickel yellow.
[0014] Preferably, the electrospinning voltage in S1, S2, and S3 is 6-20 kV.
[0015] Preferably, the total weight of the polymer and organic solvent is 100%, and the amount of inorganic infrared reflective pigment added is 1-10%. In order to ensure that the addition of the preparation equipment has color while minimizing the impact of the amount of inorganic pigment added on the radiation cooling performance, it is preferred to add 1% inorganic infrared reflective pigment.
[0016] Preferably, in S1 and S3, the total weight of polymer and organic solvent is 100%, and the polymer content is 2.1-3.1% by mass. To ensure the feasibility of spinning and to prevent the formation of a large number of spindle fibers during the spinning process, the optimal polymer content is 3% by mass.
[0017] A radiation-cooled colored nanofiber membrane with a multilayer structure prepared by the preparation method described in this invention.
[0018] The beneficial effects of this invention are:
[0019] This invention employs a combination of continuous electrospinning and electrospraying to fabricate multilayer nanofiber membranes, which exhibit superior radiative cooling performance compared to single-layer nanofiber membranes. Currently, most devices manufactured for daytime radiative cooling are white to ensure a certain level of solar reflectivity. Fabricating colored nanofiber membranes requires the addition of pigments or dyes to the spinning solution, both of which have a certain absorption rate in the solar radiation band. Inorganic infrared reflective pigments are pigments that can exhibit certain colors in the visible light region but possess infrared reflective properties in the near-infrared region. Therefore, by using inorganic near-infrared reflective pigments instead of ordinary dyes or pigments, and employing a multilayer fabrication process, the nanofiber membranes achieve multi-colored properties while minimizing the impact on their solar reflectivity.
[0020] While inorganic infrared reflective pigments can replace ordinary dyes or pigments, they still have a certain absorption rate in the solar radiation band, which affects the solar reflectivity of the radiative cooling nanofiber membrane, thus impacting its radiative cooling performance. To minimize the impact of inorganic pigments on cooling, the content of inorganic pigments in the nanofiber membrane needs to be reduced. Therefore, a multilayer structure is adopted, which ensures both the thickness of the film and imparts color to the film surface. Furthermore, the multilayer structure creates a more three-dimensional and porous structure, which has a certain effect on the solar reflectivity of the nanofiber membrane. Attached Figure Description
[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0022] Figure 1 The images show cross-sectional SEM (a) and surface SEM (b) of the radiation-cooled colored nanofiber membrane with a multilayer structure prepared in Example 1.
[0023] Figure 2 The figures show the reflectivity (a) of the solar band and the emissivity of the mid- and far-infrared band of the radiation-cooled colored nanofiber membrane with a multilayer structure prepared in Example 1.
[0024] Figure 3 The figure shown is a comparison of outdoor cooling test results of Example 1 (cmnm), Comparative Example 1 (mnm), and cotton fabric (a) and temperature difference graph (b).
[0025] Figure 4The figures shown are (a) and (b) of the outdoor cooling test results of Comparative Example 1 (nm), Comparative Example 2 (nm), and cotton fabric. Detailed Implementation
[0026] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, 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.
[0027] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.
[0028] The present invention will now be further illustrated with specific examples. The following embodiments are only for explaining the present invention and do not constitute a limitation thereof. The test samples and test procedures used in the following embodiments include the following (if the specific experimental conditions are not specified in the embodiments, they are usually performed according to conventional conditions or the conditions recommended by the reagent company; the reagents, consumables, etc. used in the following embodiments can be obtained commercially unless otherwise specified).
[0029] Example 1
[0030] A method for preparing a radiation-cooled colored nanofiber membrane with a multilayer structure, the specific steps of which are as follows:
[0031] Substrate preparation:
[0032] 3g of TPU particles were dissolved in 7g of N,N-dimethylformamide and stirred at 70℃ for 4h. After stirring until homogeneous, a TPU spinning solution was obtained. The spinning solution was then spun, with the spinning parameters set as follows: voltage: 11kV, receiving distance: 15cm, spinning speed: 1.5mL / h.
[0033] Intermediate layer preparation:
[0034] 2g of TPU particles were dissolved in 8g of N,N-dimethylformamide and stirred at 70℃ for 2h. After stirring until homogeneous, a TPU spray solution was obtained. Spinning was then carried out on the underlying nanofiber membrane. The spinning parameters were set as follows: voltage: 12kV, receiving distance: 15cm, spinning speed: 1.5mL / h.
[0035] Surface layer preparation:
[0036] 3g of TPU particles and 0.1g of titanium nickel yellow inorganic pigment were weighed and dissolved in 7g of N,N-dimethylformamide. The mixture was stirred at 70℃ for 6 hours until homogeneous, resulting in a colored TPU spinning solution. Spinning was then carried out on the intermediate nanoparticle layer. The spinning parameters were set as follows: voltage: 10kV, receiving distance: 15cm, spinning speed: 1.5mL / h.
[0037] Example 2
[0038] Substrate preparation:
[0039] 3g of TPU particles were dissolved in 7g of N,N-dimethylformamide and stirred at 70℃ for 4h. After stirring until homogeneous, a TPU spinning solution was obtained. The spinning solution was then spun, with the spinning parameters set as follows: voltage: 11kV, receiving distance: 15cm, spinning speed: 1.5mL / h.
[0040] Intermediate layer preparation:
[0041] 2g of TPU particles were dissolved in 8g of N,N-dimethylformamide and stirred at 70℃ for 2h. After stirring until homogeneous, a TPU spray solution was obtained. Spinning was then carried out on the underlying nanofiber membrane. The spinning parameters were set as follows: voltage: 12kV, receiving distance: 15cm, spinning speed: 1.5mL / h.
[0042] Surface layer preparation:
[0043] 3g of TPU particles and 0.2g of titanium nickel yellow inorganic pigment were weighed and dissolved in 7g of N,N-dimethylformamide. The mixture was stirred at 70℃ for 6 hours until homogeneous, resulting in a colored TPU spinning solution. Spinning was then carried out on the intermediate nanoparticle layer. The spinning parameters were set as follows: voltage: 10kV, receiving distance: 15cm, spinning speed: 1.5mL / h.
[0044] Example 3
[0045] Substrate preparation:
[0046] 3g of TPU particles were dissolved in 7g of N,N-dimethylformamide and stirred at 70℃ for 4h. After stirring until homogeneous, a TPU spinning solution was obtained. The spinning solution was then spun, with the spinning parameters set as follows: voltage: 11kV, receiving distance: 15cm, spinning speed: 1.5mL / h.
[0047] Intermediate layer preparation:
[0048] 2g of TPU particles were dissolved in 8g of N,N-dimethylformamide and stirred at 70℃ for 2h. After stirring until homogeneous, a TPU spray solution was obtained. Spinning was then carried out on the underlying nanofiber membrane. The spinning parameters were set as follows: voltage: 12kV, receiving distance: 15cm, spinning speed: 1.5mL / h.
[0049] Surface layer preparation:
[0050] 3g of TPU particles and 0.3g of titanium nickel yellow inorganic pigment were dissolved in 7g of N,N-dimethylformamide and stirred at 70℃ for 6 hours. After stirring until homogeneous, a colored TPU spinning solution was obtained. Spinning was then carried out on the intermediate nanoparticle layer. The spinning parameters were set as follows: voltage: 10kV, receiving distance: 15cm, spinning speed: 1.5mL / h.
[0051] Example 4
[0052] Substrate preparation:
[0053] 3g of TPU particles were dissolved in 7g of N,N-dimethylformamide and stirred at 70℃ for 4h. After stirring until homogeneous, a TPU spinning solution was obtained. The spinning solution was then spun, with the spinning parameters set as follows: voltage: 11kV, receiving distance: 15cm, spinning speed: 1.5mL / h.
[0054] Intermediate layer preparation:
[0055] 2g of TPU particles were dissolved in 8g of N,N-dimethylformamide and stirred at 70℃ for 2h. After stirring until homogeneous, a TPU spray solution was obtained. Spinning was then carried out on the underlying nanofiber membrane. The spinning parameters were set as follows: voltage: 12kV, receiving distance: 15cm, spinning speed: 1.5mL / h.
[0056] Surface layer preparation:
[0057] 3g of TPU particles and 0.4g of titanium nickel yellow inorganic pigment were weighed and dissolved in 7g of N,N-dimethylformamide. The mixture was stirred at 70℃ for 6 hours until homogeneous, resulting in a colored TPU spinning solution. Spinning was then carried out on the intermediate nanoparticle layer. The spinning parameters were set as follows: voltage: 10kV, receiving distance: 15cm, spinning speed: 1.5mL / h.
[0058] Example 5
[0059] Substrate preparation:
[0060] 3g of TPU particles were dissolved in 7g of N,N-dimethylformamide and stirred at 70℃ for 4h. After stirring until homogeneous, a TPU spinning solution was obtained. The spinning solution was then spun, with the spinning parameters set as follows: voltage: 11kV, receiving distance: 15cm, spinning speed: 1.5mL / h.
[0061] Intermediate layer preparation:
[0062] 2g of TPU particles were dissolved in 8g of N,N-dimethylformamide and stirred at 70℃ for 2h. After stirring until homogeneous, a TPU spray solution was obtained. Spinning was then carried out on the underlying nanofiber membrane. The spinning parameters were set as follows: voltage: 12kV, receiving distance: 15cm, spinning speed: 1.5mL / h.
[0063] Surface layer preparation:
[0064] 3g of TPU particles and 0.1g of titanium chromium brown inorganic pigment were dissolved in 7g of N,N-dimethylformamide and stirred at 70℃ for 6h. After stirring until homogeneous, a colored TPU spinning solution was obtained. Spinning was then carried out on the intermediate nanoparticle layer. The spinning parameters were set as follows: voltage: 10kV, receiving distance: 15cm, spinning speed: 1.5mL / h.
[0065] Example 6
[0066] Substrate preparation:
[0067] 3g of TPU particles were dissolved in 7g of N,N-dimethylformamide and stirred at 70℃ for 4h. After stirring until homogeneous, a TPU spinning solution was obtained. The spinning solution was then spun, with the spinning parameters set as follows: voltage: 11kV, receiving distance: 15cm, spinning speed: 1.5mL / h.
[0068] Intermediate layer preparation:
[0069] 2g of TPU particles were dissolved in 8g of N,N-dimethylformamide and stirred at 70℃ for 2h. After stirring until homogeneous, a TPU spray solution was obtained. Spinning was then carried out on the underlying nanofiber membrane. The spinning parameters were set as follows: voltage: 12kV, receiving distance: 15cm, spinning speed: 1.5mL / h.
[0070] Surface layer preparation:
[0071] 3g of TPU particles and 0.2g of titanium chromium brown inorganic pigment were weighed and dissolved in 7g of N,N-dimethylformamide. The mixture was stirred at 70℃ for 6 hours until homogeneous, resulting in a colored TPU spinning solution. Spinning was then carried out on the intermediate nanoparticle layer. The spinning parameters were set as follows: voltage: 10kV, receiving distance: 15cm, spinning speed: 1.5mL / h.
[0072] Example 7
[0073] Substrate preparation:
[0074] 3g of TPU particles were dissolved in 7g of N,N-dimethylformamide and stirred at 70℃ for 4h. After stirring until homogeneous, a TPU spinning solution was obtained. The spinning solution was then spun, with the spinning parameters set as follows: voltage: 11kV, receiving distance: 15cm, spinning speed: 1.5mL / h.
[0075] Intermediate layer preparation:
[0076] 2g of TPU particles were dissolved in 8g of N,N-dimethylformamide and stirred at 70℃ for 2h. After stirring until homogeneous, a TPU spray solution was obtained. Spinning was then carried out on the underlying nanofiber membrane. The spinning parameters were set as follows: voltage: 12kV, receiving distance: 15cm, spinning speed: 1.5mL / h.
[0077] Surface layer preparation:
[0078] 3g of TPU particles and 0.3g of titanium chromium brown inorganic pigment were weighed and dissolved in 7g of N,N-dimethylformamide. The mixture was stirred at 70℃ for 6 hours until homogeneous, resulting in a colored TPU spinning solution. Spinning was then carried out on the intermediate nanoparticle layer. The spinning parameters were set as follows: voltage: 10kV, receiving distance: 15cm, spinning speed: 1.5mL / h.
[0079] Example 8
[0080] Substrate preparation:
[0081] 3g of TPU particles were dissolved in 7g of N,N-dimethylformamide and stirred at 70℃ for 4h. After stirring until homogeneous, a TPU spinning solution was obtained. The spinning solution was then spun, with the spinning parameters set as follows: voltage: 11kV, receiving distance: 15cm, spinning speed: 1.5mL / h.
[0082] Intermediate layer preparation:
[0083] 2g of TPU particles were dissolved in 8g of N,N-dimethylformamide and stirred at 70℃ for 2h. After stirring until homogeneous, a TPU spray solution was obtained. Spinning was then carried out on the underlying nanofiber membrane. The spinning parameters were set as follows: voltage: 12kV, receiving distance: 15cm, spinning speed: 1.5mL / h.
[0084] Surface layer preparation:
[0085] 3g of TPU particles and 0.4g of titanium chromium brown inorganic pigment were weighed and dissolved in 7g of N,N-dimethylformamide. The mixture was stirred at 70℃ for 6 hours until homogeneous, resulting in a colored TPU spinning solution. Spinning was then carried out on the intermediate nanoparticle layer. The spinning parameters were set as follows: voltage: 10kV, receiving distance: 15cm, spinning speed: 1.5mL / h.
[0086] Comparative Example 1: Preparation of White Nanofiber Membranes
[0087] 3g of TPU particles were dissolved in 7g of N,N-dimethylformamide and stirred at 70℃ for 4h. After stirring until homogeneous, a TPU spinning solution was obtained. The spinning solution was then spun, with the spinning parameters set as follows: voltage: 11kV, receiving distance: 15cm, spinning speed: 1.5mL / h.
[0088] Intermediate layer preparation:
[0089] 2g of TPU particles were dissolved in 8g of N,N-dimethylformamide and stirred at 70℃ for 2h. After stirring until homogeneous, a TPU spray solution was obtained. Spinning was then carried out on the underlying nanofiber membrane. The spinning parameters were set as follows: voltage: 12kV, receiving distance: 15cm, spinning speed: 1.5mL / h.
[0090] Surface layer preparation:
[0091] 3g of TPU particles were dissolved in 7g of N,N-dimethylformamide and stirred at 70℃ for 4h. After stirring until homogeneous, a TPU spinning solution was obtained. The spinning solution was then spun, with the spinning parameters set as follows: voltage: 11kV, receiving distance: 15cm, spinning speed: 1.5mL / h.
[0092] Comparative Example 2: Preparation of Monolayer Nanofiber Membranes
[0093] 3g of TPU particles were dissolved in 7g of N,N-dimethylformamide and stirred at 70℃ for 4h. After stirring until homogeneous, a TPU spinning solution was obtained. The spinning solution was then spun, with the spinning parameters set as follows: voltage: 11kV, receiving distance: 15cm, spinning speed: 1.5mL / h.
[0094] Cross-sectional SEM (a) and surface SEM (b) of the radiation-cooled colored nanofiber membrane with a multilayer structure prepared in Example 1 are shown below. Figure 1 As shown; the reflectivity (a) and emissivity (middle and far-infrared) of the radiation-cooled colored nanofiber membrane with a multilayer structure in the solar band are as follows: Figure 2 As shown. Figure 2As shown, the solar reflectivity of the nanofiber membrane is about 98%, which reduces the absorption of solar energy and isolates its own heat source. The mid-infrared emissivity of the nanofiber membrane is close to 100%, which can dissipate its own heat, thereby realizing the cooling performance of the nanofiber membrane.
[0095] The outdoor cooling test comparison diagram (a) and temperature difference diagram (b) of the fiber membrane material (cmnm) prepared in Example 1 and Comparative Example 1 (mnm) with cotton fabric are shown below. Figure 3 As shown in the figure. Real-time temperature measurements were simultaneously performed on cotton fabric, multilayer nanofiber membrane, and colored multilayer nanofiber membrane. The cotton fabric had the highest real-time temperature, with a temperature difference of approximately 8°C compared to the multilayer nanofiber membrane, and approximately 4°C compared to the colored multilayer nanofiber membrane, indicating that both the multilayer and colored multilayer nanofiber membranes have a certain cooling effect.
[0096] The outdoor cooling test comparison diagram (a) and temperature difference diagram (b) of the fiber membrane materials prepared by Comparative Example 1 (nm) and Comparative Example 2 (nm) with cotton fabric are shown in Figure 2. Figure 4 As shown in the figure. Real-time temperature measurements were performed on cotton fabric, multilayer nanofiber membrane, and nanofiber membrane. The cotton fabric had the highest real-time temperature, while the multilayer nanofiber membrane had the lowest, indicating that both nanofiber membranes and multilayer nanofiber membranes possess certain cooling properties. Furthermore, due to its multilayer structure, the multilayer nanofiber membrane exhibits superior cooling performance compared to the nanofiber membrane.
[0097] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to in the method section.
[0098] The multilayered radiation-cooled colored nanofiber membrane and its preparation method provided by this invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. It should be noted that those skilled in the art can make several improvements and modifications to this invention without departing from the principles of this invention, and these improvements and modifications also fall within the protection scope of the claims of this invention.
Claims
1. A method for preparing a radiation-cooled colored nanofiber membrane with a multilayer structure, characterized in that: The fiber membrane comprises three layers: a bottom layer of nanofiber membrane, a middle layer of nanoparticles, and a surface layer of colored nanofiber membrane. The method includes the following steps: S1. Disperse polyurethane in an organic solvent, heat and stir for several hours to obtain TPU spinning solution; perform electrospinning on the spinning solution to obtain the bottom nanofiber membrane. S2. Disperse polyurethane in an organic solvent, with a polyurethane content of 15-20% by mass. After heating and stirring for several hours, obtain a TPU spray liquid. Electrostatically spray the TPU onto the nanofiber membrane obtained in S1 to obtain nanoparticles for the intermediate layer. S3. Add polyurethane and inorganic infrared reflective pigment to an organic solvent and stir for several hours to obtain a colored spinning solution; the total weight of polyurethane and organic solvent is 100%, and the amount of inorganic infrared reflective pigment added is 1%. Spinning continues on the intermediate layer obtained in S2 to form a colored nanofiber membrane on its surface, resulting in a radiation-cooled colored nanofiber membrane with a multilayer structure.
2. The method of claim 1, wherein: The organic solvent is one or more of N,N-dimethylformamide, acetone, or tetrahydrofuran.
3. The preparation method according to claim 1, characterized in that: The inorganic infrared reflective pigment is one or more of titanium chromium yellow, titanium chromium brown, cobalt green, and titanium nickel yellow.
4. The preparation method according to claim 1, characterized in that: The electrospinning voltage in S1, S2, and S3 is 6-20 kV.
5. The preparation method according to claim 1, characterized in that: In S1 and S3, the total weight of polyurethane and organic solvent is 100%, and the mass content of polyurethane is 2.1-3.1%.
6. A radiation-cooled colored nanofiber membrane with a multilayer structure prepared by the preparation method of claim 1.