Radiation refrigeration and passive heating difunctional nanofiber fabric and preparation method thereof

Abstract

The invention belongs to the technical field of functional materials, and particularly relates to a radiation refrigeration and passive heating difunctional nanofiber fabric and a preparation method thereof. According to the preparation method, PA6 is selected as a matrix, an electrostatic spinning process is adopted for processing, and meanwhile, polyaniline (PANI) grows on the surface of the PA6 fabric by adopting an in-situ polymerization method, so that a heating side with an excellent light absorption characteristic is obtained; then, a radiation refrigeration side is continuously prepared on the surface of the PA6 fabric by adopting an electrostatic spinning method, the refrigeration side is an unmodified PA6 fabric, and the fabric has a unique micro-nano fiber structure, can realize efficient Mie scattering in a sunlight wave band and has a high solar reflection characteristic. The radiation refrigeration fabric solves the problems that traditional commercial fabric lacks human body heat management regulation and control capability and the all-weather temperature regulation and control range of the radiation refrigeration fabric is limited, and is suitable for market popularization and application.

Description

Technical Field

[0001] The invention belongs to the technical field of functional materials, and in particular relates to a nanofiber fabric with dual functions of radiation cooling and passive heating and a preparation method thereof. Background Art

[0002] In recent years, the trend of global warming has become more and more significant, and people are facing the test of extremely hot environments in summer. In order to ensure human health and the normal operation of production activities, people urgently need to lower the temperature of the surrounding living environment to reduce the negative impact of the hot environment. Usually, people use refrigeration equipment such as air conditioners, air conditioning fans, fans and other equipment to assist in cooling. However, these devices require electricity to drive and operate. Refrigeration equipment is limited by spatial conditions, and people cannot use cooling equipment anytime and anywhere to keep the environment cool.

[0003] Radiative cooling is a new type of zero-power passive cooling technology. Its working principle is to reduce the input of solar radiation energy by regulating the solar reflectivity of the material itself, and at the same time radiate part of its own heat to the outer space at absolute zero in the form of infrared rays, thereby realizing the transfer of the material's own heat and achieving the effect of passive cooling. Among them, since fabrics play an important role in regulating human thermal management, the application of radiative cooling technology to fabrics can achieve effective cooling in outdoor scenes. In recent years, research on passive cooling fabrics has mainly focused on two aspects. On the one hand, it is the reprocessing and modification of traditional fabrics, mainly including the use of impregnation or scraping to compound inorganic / organic scatterers with traditional fabrics, thereby enhancing the solar reflectivity and infrared emissivity of the fabric and improving the radiative cooling efficiency of the fabric. However, this type of processing method has certain limitations. Since the modified material is added to the traditional fabric by post-processing, the adhesion and wear resistance of the modified material may weaken with the increase of service time, eventually leading to material failure. On the other hand, starting from the structural design of the fabric, fabrics with unique microstructures are prepared through processes such as electrospinning and wet stretching. These structures can effectively regulate the reflectivity of the fabric, and thus effectively reflect solar radiation under exposure to the sun.

[0004] However, a single radiant cooling fabric cannot meet the requirements of all-weather human thermal management. When the ambient temperature is too low, people need to adjust to a suitable temperature through other heating methods. Passive heating is a zero-energy heating method that does not require electric drive and is green and environmentally friendly. It converts solar radiation into thermal energy by regulating the absorption of sunlight, thereby achieving the heating effect. Combining radiant cooling with passive heating can achieve all-weather human thermal management on a zero-energy basis and broaden the temperature control range of human thermal management. Summary of the invention

[0005] In view of this, the present invention discloses a dual-functional nanofiber fabric of radiant cooling and passive heating and a preparation method thereof, which solves the problem that traditional commercial fabrics lack the ability to regulate human body thermal management and the all-weather temperature regulation range of radiant cooling fabrics is limited.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] The first technical purpose of the present invention is to provide a nanofiber fabric with dual functions of radiation cooling and passive heating, wherein the fabric has a double-sided asymmetric structure, with a radiation cooling side and a passive heating side; wherein,

[0008] The radiative cooling side is an unmodified PA6 fabric with a micrometer-scale fiber structure, which can achieve efficient Mie scattering in the solar band and show high solar reflectance;

[0009] The passive heating side is PA6 fabric modified with PANI, which has photothermal properties and exhibits high absorption of sunlight.

[0010] It should be noted that the present invention proposes a PA6 / PANI@PA6 radiative cooling and passive heating dual-function fabric prepared by electrospinning technology. The fabric has a double-sided asymmetric structure, wherein the radiative cooling side is an unmodified PA6 fabric with a micrometer-scale fiber structure, which enables it to achieve efficient Mie scattering in the solar band and exhibits high solar reflection; while the passive heating side is a PANI-modified PA6 fabric with excellent photothermal properties and exhibits high solar absorption. The present invention solves the problem that traditional commercial fabrics lack the ability to regulate human thermal management and the all-weather temperature regulation range of radiative cooling fabrics is limited, and is suitable for market promotion and application.

[0011] The second object of the present invention is to provide a method for preparing the dual-functional nanofiber fabric of radiative cooling and passive heating as described above.

[0012] In order to achieve the above object, the present invention adopts the following technical solution:

[0013] A method for preparing a nanofiber fabric with dual functions of radiation cooling and passive heating, the method specifically comprising the following steps:

[0014] (1) Dissolve the dried PA6 powder in formic acid FA solution to obtain a PA6 / FA mixed solution for later use;

[0015] (2) electrospinning the PA6 / FA mixed solution obtained in step (1) to obtain a PA6 fabric;

[0016] (3) growing polyaniline (PANI) on the surface of the PA6 fabric by an in-situ polymerization method to prepare a passive heating side, thereby obtaining PANI@PA6 fabric;

[0017] (4) The PA6 / FA mixed solution obtained in step (1) is further used to electrospin the surface of the PANI@PA6 fabric prepared in step (3) to prepare a radiant cooling side, thereby obtaining a PA6 / PANI@PA6 fabric.

[0018] Optionally, in step (1), the drying temperature of the PA6 powder is 50-60° C., and the drying time is 12-24 h; the mass fraction of PA6 in the PA6 / FA mixed solution is 15%-25%, and preferably the mass fraction of PA6 is 20%.

[0019] Optionally, the electrospinning process parameters are as follows:

[0020] The spinning voltage is 20-25 kV, the pushing speed is 0.003-0.006 mm / s, the distance from the needle to the receiver is 10-12 cm, the speed of the receiver is 100-120 rpm, and the spinning time is 24-48 h; preferably, the spinning voltage is 23 kV, the pushing speed is 0.005 mm / s, the distance from the needle to the receiver is 12 cm, the speed of the receiver is 100 rpm, and the spinning time is 24 h.

[0021] Optionally, in step (3), the in-situ polymerization method is as follows:

[0022] The PA6 fabric spun in step (2) is placed in a precursor solution to undergo a polymerization reaction;

[0023] The precursor solution is a mixed solution of hydrochloric acid, aniline and ammonium persulfate, and the molar ratio of hydrochloric acid, aniline and ammonium persulfate is (0.025-0.075):(0.01-0.05):(0.001-0.005), and the preferred molar ratio is 0.05:0.025:0.0025; specifically, the amount of hydrochloric acid used is 25-75mL, the concentration is 1mol / L, the amount of aniline added is 0.01-0.05mol, and the amount of ammonium persulfate used is 0.001-0.005mol, preferably the amount of hydrochloric acid used is 50mL, the concentration is 1mol / L, the amount of aniline added is 0.025mol, and the amount of ammonium persulfate used is 0.0025mol; and the polymerization reaction temperature is 0°C, and the reaction time is 24h.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The present invention provides a method for preparing a nanofiber fabric having dual functions of radiative cooling and passive heating. Since the method is based on an electrospinning process, it has certain scalability and can realize large-area, large-scale batch preparation of products;

[0026] (2) High solar reflection on the cooling side of the present invention: By adjusting the spinning solution formula on the cooling side, the fabric obtained has a specific fiber diameter distribution, so that it can achieve efficient Mie scattering in the solar band, thereby achieving excellent solar reflection;

[0027] (3) High solar absorption on the heating side of the present invention: The polyaniline material is firmly grown on the PA6 fabric by an in-situ polymerization method, and the modified fabric has excellent solar absorption rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0029] Figure 1 This is the SEM image of the target product of Example 1.

[0030] Figure 2 This is the SEM image of the target product of Example 2.

[0031] Figure 3 This is the SEM image of the target product of Example 3.

[0032] Figure 4 This is a solar absorptivity curve of the target product of Example 4.

[0033] Figure 5 This is the infrared spectrum of Experimental Example (1).

[0034] Figure 6 This is the solar absorption rate curve of Experimental Example (2). DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] The word "embodiment" used here as an "exemplary" does not necessarily mean that any embodiment described is superior to or better than other embodiments. Unless otherwise specified, the performance index tests in the embodiments of this application are performed using conventional test methods in the art. It should be understood that the terms described in this application are only used to describe specific implementation methods and are not used to limit the content disclosed in this application.

[0037] Unless otherwise specified, the technical and scientific terms used in this document have the same meanings as commonly understood by ordinary technicians in the technical field to which this application belongs; other experimental methods and technical means not specifically specified in this application refer to experimental methods and technical means commonly used by ordinary technicians in this field.

[0038] In order to better illustrate the content of the present application, numerous specific details are provided in the specific examples below. It should be understood by those skilled in the art that the present application can also be implemented without certain specific details. In the embodiments, some methods, means, instruments, equipment, etc. well known to those skilled in the art are not described in detail in order to highlight the main purpose of the present application.

[0039] Under the premise of no conflict, the technical features disclosed in the embodiments of the present application can be combined arbitrarily, and the resulting technical solutions belong to the contents disclosed in the embodiments of the present application.

[0040] The invention discloses a nanofiber fabric with dual functions of radiation cooling and passive heating and a preparation method thereof.

[0041] In order to better understand the present invention, the present invention is further specifically described below through the following examples, but it should not be understood as a limitation of the present invention. Some non-essential improvements and adjustments made by technicians in this field based on the above invention content are also considered to fall within the protection scope of the present invention.

[0042] Example 1

[0043] Weigh 2.5g of PA6 powder after drying on a balance, and select FA as the spinning solvent to dissolve PA6, in which the mass fraction of PA6 accounts for 20%. Then use a magnetic stirrer to stir at room temperature for 24 hours to obtain a PA6 electrospinning mixed solution. Move the prepared spinning solution to the operating table for electrospinning. The spinning voltage is set to 23kV, the withdrawal speed is controlled to 0.005mm / s, the distance from the needle to the receiver is 12cm, the speed of the receiver is 100rpm, the spinning time is 24h, and the PA6 fabric before modification is obtained after the spinning is completed. Figure 1 This is the SEM image of the fabric.

[0044] Example 2

[0045] PA6 fabrics with different size distribution ranges were prepared by changing the proportion of PA6 in the electrospinning solution. 2.5g of PA6 powder after drying was weighed on a balance, and FA was selected as the spinning solvent to dissolve PA6, in which the mass fraction of PA6 accounted for 25%. Subsequently, a magnetic stirrer was used to stir at room temperature for 24 hours to obtain a PA6 electrospinning mixed solution. The prepared spinning solution was moved to the operating table for electrospinning. The spinning voltage was set to 24kV, the withdrawal speed was controlled to 0.003mm / s, the distance from the needle to the receiver was 12cm, the speed of the receiver was 100rpm, the spinning time was 24h, and PA6 fabric was obtained after the spinning was completed. Figure 2 is the SEM picture of the fabric, and its fiber structure uniformity is lower than that of the fabric prepared in Example 1.

[0046] Example 3

[0047] Since the fabric with 20% PA6 in the spinning solution has a relatively uniform size distribution, the PA6 fabric prepared in Example 1 was used, and the PA6 fabric was placed in the precursor solution for in-situ polymerization growth of PANI. The solution composition was a mixture of aniline, ammonium persulfate, and hydrochloric acid, wherein the amount of hydrochloric acid was 50mL, the concentration was 1mol / L, the amount of aniline added was 0.025mol, and the amount of ammonium persulfate was 0.0025mol. The reaction was carried out under ice bath conditions at 0°C for 24h, and finally the heated side PANI@PA6 fabric was obtained.

[0048] from Figure 3 It can be seen that the obtained PANI@PA6 fabric on the heating side has a nanofiber skeleton structure, and polyaniline is evenly distributed in the fabric and tightly combined with the fiber skeleton.

[0049] Example 4

[0050] The absorbance of the fabric on the heating side can be controlled by changing the amount of potassium persulfate in the polymerization precursor solution. The fabric in which PA6 accounts for 20% in the spinning solution has a relatively uniform size distribution. The PA6 fabric prepared in Example 1 is used, and the PA6 fabric is placed in the precursor solution for in-situ polymerization growth of PANI. The solution composition is a mixture of aniline, ammonium persulfate, and hydrochloric acid, wherein the amount of hydrochloric acid is 50mL, the concentration is 1mol / L, the amount of aniline added is 0.025mol, and the amount of ammonium persulfate is 0.005mol. The reaction is carried out in an ice bath at 0°C for 24h to obtain the PANI@PA6 fabric on the heating side. Figure 4 It can be seen that its absorbance is slightly lower than that of the fabric prepared in Example 3.

[0051] Example 5

[0052] A cooling layer PA6 fabric was spun on the surface of the heating side PANI@PA6 fabric obtained in Example 3, also by the electrospinning method. The spinning solution was a PA6 / FA mixed solution, in which the mass fraction of PA6 was 20%. The spinning voltage was set to 23 kV, the withdrawal speed was controlled to 0.005 mm / s, the distance from the needle to the receiver was 12 cm, the rotation speed of the receiver was 100 rpm, and the spinning time was 24 h. After the spinning, the final target product PA6 / PANI@PA6 fabric was obtained.

[0053] Figure 1 This is the SEM image of the PA6 fabric on the cooling side. It can be seen that the fibers of the PA6 fabric obtained are densely interlaced, the fiber diameters are evenly distributed, and the fiber stacking forms an irregular pore structure. There are a small amount of beaded structures on the fibers, which helps to achieve efficient solar reflection.

[0054] In order to further demonstrate the beneficial effects of the present invention and to better understand the present invention, the following comparative examples and test examples are used to further illustrate the technical features disclosed in the present invention, but they should not be understood as limiting the present invention. Other improvements made by those skilled in the art based on the above invention content without creative work are also considered to fall within the scope of protection of the present invention.

[0055] Comparative Example 1

[0056] Weigh 2.5g of PA6 powder after drying on a balance, and select FA as the spinning solvent to dissolve PA6, in which the mass fraction of PA6 accounts for 10%. Then use a magnetic stirrer to stir at room temperature for 24 hours to obtain a PA6 electrospinning mixed solution. Move the prepared spinning solution to the operating table for electrospinning. The spinning voltage is set to 24kV, the withdrawal speed is controlled to 0.003mm / s, the distance from the needle to the receiver is 12cm, the speed of the receiver is 100rpm, the spinning time is 24h, and the PA6 fabric is obtained after the spinning is completed. The fiber diameter distribution of the fabric obtained at this concentration is uneven, and beaded spray occurs.

[0057] Comparative Example 2

[0058] The PA6 fabric prepared by the method of Example 1 was selected, and the fabric was placed in a precursor solution to in-situ polymerize and grow PANI. The solution composition was a mixture of aniline, ammonium persulfate, and hydrochloric acid, wherein the amount of hydrochloric acid was 10 mL, the concentration was 1 mol / L, the amount of aniline added was 0.025 mol, and the amount of ammonium persulfate was 0.0025 mol. The reaction was carried out under ice bath conditions at 0°C for 24 hours to obtain PANI@PA6 fabric. The amount of hydrochloric acid used was too little, the acidity of the reaction system was insufficient, the polymerization reaction was not sufficient, and the absorbance of the prepared fabric was not high.

[0059] Comparative Example 3

[0060] The PA6 fabric prepared by the method of Example 1 was selected, and the fabric was placed in a precursor solution to in-situ polymerize and grow PANI. The solution composition was a mixture of aniline, ammonium persulfate, and hydrochloric acid, wherein the amount of hydrochloric acid was 50 mL, the concentration was 1 mol / L, the amount of aniline added was 0.025 mol, and the amount of ammonium persulfate was 0.01 mol. The reaction was carried out under ice bath conditions at 0°C for 24 hours to obtain PANI@PA6 fabric. The amount of ammonium persulfate was too much, the polymerization reaction was rapid and violent, and the polymerization product PANI was unevenly distributed.

[0061] Comparative Example 4

[0062] The PA6 fabric prepared by the method of Example 1 was selected, and the fabric was placed in a precursor solution to in-situ polymerize and grow PANI. The solution composition was a mixture of aniline, ammonium persulfate, and hydrochloric acid, wherein the amount of hydrochloric acid was 50 mL, the concentration was 1 mol / L, the amount of aniline added was 0.1 mol, and the amount of ammonium persulfate was 0.0025 mol. The reaction was carried out under ice bath conditions at 0°C for 24 hours to obtain PANI@PA6 fabric. The amount of aniline was too much, the polymerization reaction was slow and insufficient, and the absorbance of the prepared fabric was low.

[0063] Test example:

[0064] (1) Perform Fourier transform infrared spectroscopy test on the target product. Figure 5 Figure 1 is the infrared test result of the target product, which tests pure PA6, pure PANI and the PANI@PA6 sample prepared in Example 3. The characteristic absorption peaks of PA6 and PANI appear in the PANI@PA6 sample at the same time, indicating that PANI is successfully grown on the PA6 fabric by in-situ polymerization.

[0065] (2) The target product obtained in Example 5 was subjected to a solar light absorption test. Figure 6 The solar absorptivity curves of the cooling and heating sides of PA6 / PANI@PA6 fabrics are shown in Figure 2. The PA6 fabric on the cooling side has a lower solar absorptivity, with an average absorptivity of less than 20%, which can effectively resist the heat brought by solar radiation absorption, thereby realizing the radiative cooling function. The PANI@PA6 fabric on the heating side has a high solar absorptivity, absorbing more than 90% on average, and can achieve passive heating under solar radiation. Figure 4 It can be seen that the light absorption effect is better than that of black cotton cloth.

[0066] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A nanofiber fabric with dual functions of radiative cooling and passive heating, It is characterized in that The fabric has a double-sided asymmetric structure, with a radiant cooling side and a passive heating side; wherein, The radiative cooling side is an unmodified PA6 fabric with a micrometer-scale fiber structure, which can achieve efficient Mie scattering in the solar band and show high solar reflectance; The passive heating side is PA6 fabric modified by PANI, which has photothermal properties and exhibits high absorption of sunlight.

2. A method for preparing the dual-functional nanofiber fabric for radiative cooling and passive heating as claimed in claim 1, It is characterized in that The method specifically comprises the following steps: (1) Dissolve the dried PA6 powder in formic acid FA solution to obtain a PA6 / FA mixed solution for later use; (2) electrospinning the PA6 / FA mixed solution obtained in step (1) to obtain a PA6 fabric; (3) growing polyaniline (PANI) on the surface of the PA6 fabric by an in-situ polymerization method to prepare a passive heating side, thereby obtaining PANI@PA6 fabric; (4) The PA6 / FA mixed solution obtained in step (1) is further used to electrospin the surface of the PANI@PA6 fabric prepared in step (3) to prepare a radiant cooling side, thereby obtaining a PA6 / PANI@PA6 fabric.

3. The method for preparing the dual-functional nanofiber fabric of radiative cooling and passive heating according to claim 2, It is characterized in that In step (1), the drying temperature of the PA6 powder is 50-60° C., and the drying time is 12-24 hours; the mass fraction of PA6 in the PA6 / FA mixed solution is 15%-25%.

4. The method for preparing the dual-functional nanofiber fabric of radiative cooling and passive heating according to claim 2, It is characterized in that The electrospinning process parameters are as follows: The spinning voltage is 20-25 kV, the pushing speed is 0.003-0.006 mm / s, the distance from the needle to the receiver is 10-12 cm, the rotation speed of the receiver is 100-120 rpm, and the spinning time is 24-48 h.

5. The method for preparing the dual-functional nanofiber fabric of radiative cooling and passive heating according to claim 2, It is characterized in that In step (3), the in-situ polymerization method is as follows: The PA6 fabric spun in step (2) is placed in a precursor solution to undergo a polymerization reaction; The precursor solution is a mixed solution of hydrochloric acid, aniline and ammonium persulfate, and the molar ratio of hydrochloric acid, aniline and ammonium persulfate is (0.025-0.075):(0.01-0.05):(0.001-0.005); The reaction temperature is 0°C and the reaction time is 24-30h.

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