Multifunctional flexible composite aerogel with electric-thermal deicing, anti-icing and microwave absorption functions and preparation method of multifunctional flexible composite aerogel

Abstract

The invention discloses multifunctional flexible composite aerogel with electric-thermal deicing, anti-icing and microwave absorption functions and a preparation method of the multifunctional flexible composite aerogel. According to the preparation method, deionized water is used as a solvent of a silicon source precursor, and nickel-copper polyurethane conductive sponge is used as a reinforcing phase. The silicon dioxide aerogel is uniformly and tightly combined to a framework of the nickel-copper polyurethane conductive sponge through vacuum impregnation, and the composite aerogel has excellent super-hydrophobicity on the whole due to the fact that the surface of a silicon source precursor contains a large number of methyl groups. Meanwhile, the silicon dioxide aerogel and the nickel-copper polyurethane conductive sponge have excellent flexibility, so that the flexible composite aerogel still has excellent flexibility and structural stability. In addition, the composite material aerogel also has multiple key attributes such as electric-thermal deicing, icing prevention and microwave absorptivity. The problems that an existing anti-icing material is high in energy consumption in the anti-icing process and short in icing delay time are solved.

Description

Technical Field

[0001] The invention belongs to the technical field of electric-thermal deicing, anti-icing and microwave absorption, and specifically relates to a multifunctional flexible composite aerogel with electric-thermal deicing, anti-icing and microwave absorption and a preparation method thereof. Background Art

[0002] With the rapid development of microwave technology, stealth plays an increasingly important role in protecting equipment safety, and the development of multifunctional microwave absorbing materials is becoming increasingly important. In some cases, equipment needs to operate in extremely cold and humid environments, which requires absorbing materials to have excellent absorbing performance while also having excellent deicing and anti-icing properties.

[0003] At present, there are related studies. For example, China Invention Patent Publication No. CN117587625A discloses a method for preparing a lightweight, super-hydrophobic and self-cleaning rGO / LDH / PPy composite absorbing fabric, which is mainly formed by constructing a multi-dimensional heterogeneous structure of rGO / LDH / PPy layers on aramid non-woven fabric by hydrothermal method and in-situ growth, and then modifying the super-hydrophobic absorbing fabric with a low surface energy material modification layer. The super-hydrophobic absorbing fabric has excellent electromagnetic wave absorption performance and super-hydrophobicity, and has good flexibility, heat insulation and flame retardant properties. The composite absorbing fabric obtained by this method has a complex preparation process, high cost and low mechanical strength.

[0004] Chinese invention patent publication number CN109627905A discloses a multifunctional coating with self-cleaning, anti-icing and microwave absorption and a preparation method thereof. The coating mainly comprises the following steps: firstly synthesizing a low surface energy nanoparticle oily dispersion and a Fe3O4 / rGO / PANI / resin composite coating respectively, and then spraying the Fe3O4 / rGO / PANI / resin composite coating and the low surface energy nanoparticle oily dispersion on a substrate in turn to obtain a self-cleaning and anti-icing microwave absorption coating. The coating has excellent absorption performance, self-cleaning and anti-icing performance, and can be prepared on a large surface in a controllable manner. The multifunctional coating obtained by the method loses outer nanoparticles under strong mechanical stress, resulting in the disappearance of hydrophobicity and a decrease in anti-icing ability.

[0005] In order to achieve reliable application of materials in extreme environments, it is urgent to develop multifunctional integrated microwave absorbing materials. Summary of the invention

[0006] In view of the problems of complex process, high cost and poor mechanical stability of multifunctional integrated microwave absorbing materials in the prior art, the present invention provides a multifunctional flexible composite aerogel with electric-thermal deicing, anti-icing and microwave absorption and a preparation method thereof. The present invention makes full use of the key properties of aerogel, broadens the application of aerogel in anti-icing and microwave absorption, and solves the problems of high energy consumption in the anti-icing process and short delayed icing time of existing anti-icing materials.

[0007] The technical solution of the present invention is as follows:

[0008] The present invention proposes a method for preparing a multifunctional flexible composite aerogel with electric-thermal deicing, anti-icing and microwave absorption under normal pressure. The basic steps are: first, silica sol is completely filled into a conductive sponge by a vacuum impregnation method, the gel structure is stabilized by gelation, aging and replacement, and the multifunctional flexible composite aerogel is obtained by normal pressure drying.

[0009] The present invention discloses a method for preparing a multifunctional flexible composite aerogel with electric-thermal deicing, anti-icing and microwave absorption. The preparation method uses deionized water as the solvent of the silicon source precursor and the nickel-copper polyurethane conductive sponge as the reinforcing phase. The silica aerogel is uniformly and tightly bonded to the skeleton of the nickel-copper polyurethane conductive sponge by vacuum impregnation. Since the surface of the silicon source precursor contains a large amount of methyl groups, the composite aerogel has excellent super-hydrophobicity as a whole. At the same time, since the silica aerogel and the nickel-copper polyurethane conductive sponge themselves have excellent flexibility, the flexible composite aerogel still has excellent flexibility and structural stability. In addition, due to the special properties of the material itself, this composite aerogel also has multiple key properties such as electric-thermal deicing, anti-icing and microwave absorption.

[0010] The purpose of the present invention is achieved through the following technical solutions:

[0011] A method for preparing a multifunctional flexible composite aerogel with electric-thermal deicing, anti-icing and microwave absorption, comprising the following steps:

[0012] (1) mixing a surfactant and deionized water in proportion, adding a silicon source precursor after sufficient reaction to completely hydrolyze the mixture to obtain a silica sol, and the reaction was carried out at a constant temperature of 35° C.;

[0013] The molar ratio of the surfactant, deionized water and silicon source precursor is (0.0002-0.0008):(2-2.8):(0.12-0.21);

[0014] The surfactant is cetyltrimethylammonium bromide (CTAB) or cetyltrimethylammonium chloride (MSDS);

[0015] The silicon source precursor is methyltrimethoxysilane (MTMS) or methyltriethoxysilane (MTES);

[0016] (2) adding ammonia water to the silica sol obtained in step (1) to make the pH of the sol greater than 7, and then completely immersing the sol into a conductive sponge in a vacuum environment, and gelling and aging in an environment of 35° C. for 12 h to 24 h to obtain a conductive sponge-reinforced silica composite wet gel;

[0017] The conductive sponge is one of nickel-copper polyurethane conductive sponge, porous magnetic metal foam or carbon nanotube conductive polyurethane sponge;

[0018] (3) subjecting the conductive sponge-enhanced silica composite wet gel obtained in step (2) to solvent replacement, wherein the replacement solvent is n-hexane or anhydrous ethanol, the replacement time is 1 d to 2 d, and the replacement temperature is 60° C. to 80° C.;

[0019] (4) drying the conductive sponge-reinforced silica composite wet gel obtained by substitution in step (3) under normal pressure at a drying temperature of 80° C. to 90° C. for a drying time of 1 to 2 days to obtain a multifunctional flexible composite aerogel having electric-thermal deicing, anti-icing and microwave absorption. The typical properties of the prepared multifunctional flexible composite aerogel having electric-thermal deicing, anti-icing and microwave absorption are as follows:

[0020] ① The multifunctional flexible composite aerogel has excellent mechanical properties, good block properties after drying, no cracking, and a density of 0.11g / cm 3 -0.28g / cm 3 , after 1000 times of compression and bending deformation, it can recover to its original shape;

[0021] ② The multifunctional flexible composite aerogel has super hydrophobic properties as a whole, and the contact angle is maintained at 150°-155°;

[0022] ③ The multifunctional flexible composite aerogel has electric-thermal deicing and anti-icing properties in cold and humid environments, has excellent electric-thermal conversion effect and excellent thermal insulation performance, can quickly melt frozen water droplets, and delays freezing time by 1500s in an environment of -20°C;

[0023] ④ The multifunctional flexible composite aerogel has excellent electromagnetic wave absorption properties, wherein the three-dimensional structure constructs a double interface polarization, so that the minimum reflection loss of the flexible composite aerogel at a thickness of 2.2 mm reaches -19.07 dB, and the absorption bandwidth reaches 8.24 GHz.

[0024] Furthermore, the surfactant described in step (1) is preferably cetyltrimethylammonium bromide (CTAB).

[0025] Furthermore, the silicon source precursor in step (1) is preferably methyltrimethoxysilane (MTMS).

[0026] Furthermore, the gelation and aging in step (2) is preferably performed for 12 hours.

[0027] Furthermore, the conductive sponge described in step (2) is preferably a nickel-copper polyurethane conductive sponge.

[0028] Furthermore, in the solvent replacement described in step (3), the preferred replacement solvent is n-hexane, the replacement time is 1 day, and the replacement temperature is 60°C.

[0029] The present invention also relates to a multifunctional flexible composite aerogel with electric-thermal deicing, anti-icing and microwave absorption, which is obtained by using the above-mentioned preparation method of a multifunctional flexible composite aerogel with electric-thermal deicing, anti-icing and microwave absorption. The typical properties of the prepared multifunctional flexible composite aerogel with electric-thermal deicing, anti-icing and microwave absorption are:

[0030] ① The multifunctional flexible composite aerogel has excellent mechanical properties, good block properties after drying, no cracking, and a density of 0.11g / cm 3 -0.28g / cm 3 , after 1000 times of compression and bending deformation, it can recover to its original shape;

[0031] ② The multifunctional flexible composite aerogel has super hydrophobic properties as a whole, and the contact angle is maintained at 150°-155°;

[0032] ③ The multifunctional flexible composite aerogel has electric-thermal deicing and anti-icing properties in cold and humid environments, has excellent electric-thermal conversion effect and excellent thermal insulation performance, can quickly melt frozen water droplets, and delays freezing time by 1500s in an environment of -20°C;

[0033] ④ The multifunctional flexible composite aerogel has excellent electromagnetic wave absorption properties, wherein the three-dimensional structure constructs a double interface polarization, so that the minimum reflection loss of the flexible composite aerogel at a thickness of 2.2 mm reaches -19.07 dB, and the absorption bandwidth reaches 8.24 GHz.

[0034] Compared with the prior art, the present invention has the following advantages:

[0035] 1. The preparation method of a multifunctional flexible composite aerogel with electric-thermal deicing, anti-icing and microwave absorption described in the present invention provides a method for improving its mechanical properties by utilizing the three-dimensional network structure of nickel-copper polyurethane conductive sponge and the synergistic protective effect of silica flexible aerogel, and the method includes the steps of vacuum impregnation, aging, replacement and drying. The selection of appropriate aging and replacement time and temperature, as well as the type of replacement solvent can reduce the damage to the silica aerogel structure and pores when the gel is dried, so that the silica aerogel and the nickel-copper polyurethane conductive sponge are tightly combined into a whole, so that the structure is enhanced and has good flexibility and mechanical properties. In addition, the multifunctional flexible composite aerogel also has the characteristics of electric-thermal deicing, anti-icing and microwave absorption.

[0036] 2. The multifunctional flexible composite aerogel with electric-thermal deicing, anti-icing and microwave absorption described in the present invention can be used as a material integrating deicing, anti-icing and microwave absorption in extremely cold and humid environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention.

[0038] Figure 1 is a field emission scanning electron microscope image of the nickel-copper polyurethane conductive sponge, silica aerogel and flexible composite aerogel prepared in Example 3 of the present invention;

[0039] Figure 2 is a macroscopic photograph of the bending state and super-hydrophobic properties of the flexible composite aerogel prepared in Example 3 of the present invention;

[0040] Figure 3 This is a photograph of the flexible composite aerogel prepared in Example 3 of the present invention at a large bending angle of 72°;

[0041] Figure 4 is a compression-rebound macroscopic photograph of the flexible composite aerogel prepared in Example 3 of the present invention;

[0042] Figure 5 This is a macroscopic photograph of the deicing and electro-thermal effects of the flexible composite aerogel prepared in Example 3 of the present invention;

[0043] Figure 6 This is a macroscopic photograph of the delayed freezing of the flexible composite aerogel prepared in Example 3 of the present invention;

[0044] Figure 7 is a graph showing the wave absorption performance of the flexible composite aerogel prepared in Example 3 of the present invention at different thicknesses;

[0045] Figure 8 This is a graph showing the shrinkage rate of the pure aerogel of Comparative Example 1 of the present invention at different aging temperatures;

[0046] Fig. 9 This is a graph of the shrinkage of the aerogel prepared in Comparative Example 2 of the present invention after drying at a replacement temperature of 50°C to 90°C. DETAILED DESCRIPTION

[0047] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. 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.

[0048] Embodiment 1:

[0049] A method for preparing a multifunctional flexible composite aerogel with electric-thermal deicing, anti-icing and microwave absorption, comprising the following steps:

[0050] (1) mixing a surfactant and deionized water uniformly by mechanical stirring, adding a silicon source precursor to hydrolyze to obtain a silica sol after sufficient reaction, and the reaction is carried out at a constant temperature of 35° C.; the surfactant is hexadecyltrimethylammonium bromide, and the silicon source precursor is methyltrimethoxysilane; in terms of molar ratio, the molar ratio of surfactant: deionized water: silicon source precursor is 0.0002:2.2:0.15;

[0051] (2) adding diluted ammonia water to the sol obtained in step (1) to make the pH of the sol greater than 7, and then completely impregnating the sol into a nickel-copper polyurethane conductive sponge in a vacuum environment, and allowing the sol to stand after the impregnation to obtain a silicon dioxide composite wet gel; the amount of ammonia water added is ensured to be calculated in a molar ratio of ammonia water:silicon source precursor=0.002:0.12;

[0052] (3) aging the silica composite wet gel obtained in step (2) in a constant temperature environment of 35° C. for 12 h;

[0053] (4) performing solvent replacement of the silicon dioxide composite wet gel obtained in step (3) with n-hexane at 60° C. for 1 day;

[0054] (5) The replaced silica composite wet gel obtained in step (4) is dried at 80° C. under normal pressure to obtain a multifunctional flexible composite aerogel.

[0055] The obtained multifunctional flexible composite aerogel with electric-thermal deicing, anti-icing and microwave absorption has good block properties after drying, no cracking, and a density of 0.15g / cm 3-0.20g / cm 3 , and can return to its original shape after 1,000 times of compression and bending deformation; the flexible composite aerogel with electro-thermal deicing, anti-icing and microwave absorption has super-hydrophobic properties as a whole, and the contact angle is maintained above 155°; it has electro-thermal deicing and anti-icing properties in cold and humid environments, as well as excellent wave absorption properties.

[0056] Embodiment 2:

[0057] A method for preparing a multifunctional flexible composite aerogel with electric-thermal deicing, anti-icing and microwave absorption, comprising the following steps:

[0058] (1) mixing a surfactant and deionized water uniformly by mechanical stirring, adding a silicon source precursor to hydrolyze to obtain a silica sol after sufficient reaction, and the reaction is carried out at a constant temperature of 35° C.; the surfactant is hexadecyltrimethylammonium bromide, and the silicon source precursor is methyltrimethoxysilane; in terms of molar ratio, the molar ratio of surfactant: deionized water: silicon source precursor is 0.0005:2.2:0.15;

[0059] (2) adding diluted ammonia water to the sol obtained in step (1) to make the pH of the sol greater than 7, and then completely impregnating the sol into a nickel-copper polyurethane conductive sponge in a vacuum environment, and allowing the sol to stand after the impregnation to obtain a silicon dioxide composite wet gel; the amount of ammonia water added is ensured to be calculated in a molar ratio of ammonia water:silicon source precursor=0.002:0.12;

[0060] (3) aging the silica composite wet gel obtained in step (2) in a constant temperature environment of 35° C. for 12 h;

[0061] (4) performing solvent replacement of the silicon dioxide composite wet gel obtained in step (3) with n-hexane at 60° C. for 1 day;

[0062] (5) The replaced silica composite wet gel obtained in step (4) is dried at 80° C. under normal pressure to obtain a multifunctional flexible composite aerogel.

[0063] The obtained multifunctional flexible composite aerogel with electric-thermal deicing, anti-icing and microwave absorption has good block properties after drying, no cracking, and a density of 0.14g / cm 3 -0.22g / cm 3 , and can return to its original shape after 1,000 times of compression and bending deformation; the flexible composite aerogel with electro-thermal deicing, anti-icing and microwave absorption has super-hydrophobic properties as a whole, and the contact angle is maintained above 155°; it has electro-thermal deicing and anti-icing properties in cold and humid environments, as well as excellent wave absorption properties.

[0064] Embodiment 3:

[0065] A method for preparing a multifunctional flexible composite aerogel with electric-thermal deicing, anti-icing and microwave absorption, comprising the following steps:

[0066] (1) mixing a surfactant and deionized water uniformly by mechanical stirring, adding a silicon source precursor to hydrolyze to obtain a silica sol after sufficient reaction, and the reaction is carried out at a constant temperature of 35° C.; the surfactant is hexadecyltrimethylammonium bromide, and the silicon source precursor is methyltrimethoxysilane; in terms of molar ratio, the molar ratio of surfactant: deionized water: silicon source precursor is 0.0008:2.2:0.15;

[0067] (2) adding diluted ammonia water to the sol obtained in step (1) to make the pH of the sol greater than 7, and then completely impregnating the sol into a nickel-copper polyurethane conductive sponge in a vacuum environment, and allowing the sol to stand after the impregnation to obtain a silicon dioxide composite wet gel; the amount of ammonia water added is ensured to be calculated in a molar ratio of ammonia water:silicon source precursor=0.002:0.12;

[0068] (3) aging the silica composite wet gel obtained in step (2) in a constant temperature environment of 35° C. for 12 h;

[0069] (4) performing solvent replacement of the silicon dioxide composite wet gel obtained in step (3) with n-hexane at 60° C. for 1 day;

[0070] (5) The replaced silica composite wet gel obtained in step (4) is dried at 80° C. under normal pressure to obtain a multifunctional flexible composite aerogel.

[0071] The obtained multifunctional flexible composite aerogel with electric-thermal deicing, anti-icing and microwave absorption has good block properties after drying, no cracking, and a density of 0.13g / cm 3 -0.27g / cm 3 , and can return to its original shape after 1,000 compression and bending deformations; the flexible composite aerogel as a whole has super-hydrophobic properties, and the contact angle is maintained above 153°; it has electric-thermal deicing and anti-icing properties in cold and humid environments, as well as excellent wave absorption properties.

[0072] pass Figure 1 It can be seen that the prepared nickel-copper polyurethane conductive sponge, silica aerogel and flexible composite aerogel provide structural guarantees for the stable application of nickel-copper polyurethane conductive sponge, silica aerogel and flexible composite aerogel due to the tight filling of silica aerogel;

[0073] pass Figure 2 , Figure 3 and Figure 4It can be seen that the flexible composite aerogel has excellent mechanical properties and superhydrophobicity, and also has excellent tailorability;

[0074] pass Figure 5 It can be seen that the flexible composite aerogel has an excellent electrical-thermal conversion effect and can quickly melt frozen water droplets;

[0075] pass Figure 6 It can be seen that the flexible composite aerogel has excellent anti-icing properties. Due to the excellent thermal insulation performance of silica aerogel, the delayed freezing time can reach 1500s in an environment of -20℃;

[0076] pass Figure 7 It can be seen that the flexible composite aerogel has excellent electromagnetic wave absorption properties, so the three-dimensional structure constructs a double interface polarization, so that the minimum reflection loss of the flexible composite aerogel at a thickness of 2.2 mm reaches -19.07 dB, and the absorption bandwidth reaches 8.24 GHz;

[0077] pass Figures 1 to 7 It can be seen that this flexible composite aerogel provides an effective idea for designing functional materials that can melt ice, prevent icing and absorb waves in extreme environments. It will have broad development prospects in the future in many fields such as aerospace, base navigation and radar stealth.

[0078] Embodiment 4:

[0079] A method for preparing a multifunctional flexible composite aerogel with electric-thermal deicing, anti-icing and microwave absorption, comprising the following steps:

[0080] (1) mixing a surfactant and deionized water uniformly by mechanical stirring, adding a silicon source precursor to hydrolyze to obtain a silica sol after sufficient reaction, and the reaction is carried out at a constant temperature of 35° C.; the surfactant is hexadecyltrimethylammonium bromide, and the silicon source precursor is methyltrimethoxysilane; in terms of molar ratio, the molar ratio of surfactant: deionized water: silicon source precursor is 0.0002:2.2:0.15;

[0081] (2) adding diluted ammonia water to the sol obtained in step (1) to make the pH of the sol greater than 7, and then completely impregnating the sol into a nickel-copper polyurethane conductive sponge in a vacuum environment, and allowing the sol to stand after the impregnation to obtain a silicon dioxide composite wet gel; the amount of ammonia water added is ensured to be calculated in a molar ratio of ammonia water:silicon source precursor=0.002:0.12;

[0082] (3) aging the silica composite wet gel obtained in step (2) in a constant temperature environment of 35° C. for 12 h;

[0083] (4) performing solvent replacement of the silicon dioxide composite wet gel obtained in step (3) with anhydrous ethanol at 60° C. for 1 day;

[0084] (5) The replaced silica composite wet gel obtained in step (4) is dried at 80° C. under normal pressure to obtain a multifunctional flexible composite aerogel.

[0085] The obtained multifunctional flexible composite aerogel with electric-thermal deicing, anti-icing and microwave absorption has good block properties after drying, no cracking, and a density of 0.11g / cm 3 -0.24g / cm 3 , and can return to its original shape after 1,000 times of compression and bending deformation; the flexible composite aerogel with electric-thermal deicing, anti-icing and microwave absorption has super-hydrophobic properties as a whole, and the contact angle is maintained above 153°; it has electric-thermal deicing and anti-icing properties in cold and humid environments, as well as excellent wave absorption properties.

[0086] Embodiment 5:

[0087] A method for preparing a multifunctional flexible composite aerogel with electric-thermal deicing, anti-icing and microwave absorption, comprising the following steps:

[0088] (1) mixing a surfactant and deionized water uniformly by mechanical stirring, adding a silicon source precursor to hydrolyze to obtain a silica sol after sufficient reaction, and the reaction is carried out at a constant temperature of 35° C.; the surfactant is hexadecyltrimethylammonium bromide, and the silicon source precursor is methyltrimethoxysilane; in terms of molar ratio, the molar ratio of surfactant: deionized water: silicon source precursor is 0.0005:2.2:0.15;

[0089] (2) adding diluted ammonia water to the sol obtained in step (1) to make the pH of the sol greater than 7, and then completely impregnating the sol into a nickel-copper polyurethane conductive sponge in a vacuum environment, and allowing the sol to stand after the impregnation to obtain a silicon dioxide composite wet gel; the amount of ammonia water added is ensured to be calculated in a molar ratio of ammonia water:silicon source precursor=0.002:0.12;

[0090] (3) aging the silica composite wet gel obtained in step (2) in a constant temperature environment of 35° C. for 12 h;

[0091] (4) performing solvent replacement of the silicon dioxide composite wet gel obtained in step (3) with anhydrous ethanol at 60° C. for 1 day;

[0092] (5) The replaced silica composite wet gel obtained in step (4) is dried at 80° C. under normal pressure to obtain a multifunctional flexible composite aerogel.

[0093] The obtained multifunctional flexible composite aerogel with electric-thermal deicing, anti-icing and microwave absorption has good block properties after drying, no cracking, and a density of 0.15g / cm 3 -0.27g / cm 3 , and can return to its original shape after 1,000 times of compression and bending deformation; the flexible composite aerogel with electro-thermal deicing, anti-icing and microwave absorption has super-hydrophobic properties as a whole, and the contact angle is maintained above 155°; it has electro-thermal deicing and anti-icing properties in cold and humid environments, as well as excellent wave absorption properties.

[0094] Embodiment 6:

[0095] A method for preparing a multifunctional flexible composite aerogel with electric-thermal deicing, anti-icing and microwave absorption, comprising the following steps:

[0096] (1) mixing a surfactant and deionized water uniformly by mechanical stirring, adding a silicon source precursor to hydrolyze to obtain a silica sol after sufficient reaction, and the reaction is carried out at a constant temperature of 35° C.; the surfactant is hexadecyltrimethylammonium bromide, and the silicon source precursor is methyltrimethoxysilane; in terms of molar ratio, the molar ratio of surfactant: deionized water: silicon source precursor is 0.0008:2.2:0.15;

[0097] (2) adding diluted ammonia water to the sol obtained in step (1) to make the pH of the sol greater than 7, and then completely impregnating the sol into a nickel-copper polyurethane conductive sponge in a vacuum environment, and allowing the sol to stand after the impregnation to obtain a silicon dioxide composite wet gel; the amount of ammonia water added is ensured to be calculated in a molar ratio of ammonia water:silicon source precursor=0.002:0.12;

[0098] (3) aging the silica composite wet gel obtained in step (2) in a constant temperature environment of 35° C. for 12 h;

[0099] (4) performing solvent replacement of the silicon dioxide composite wet gel obtained in step (3) with anhydrous ethanol at 60° C. for 1 day;

[0100] (5) The replaced silica composite wet gel obtained in step (4) is dried at 80° C. under normal pressure to obtain a multifunctional flexible composite aerogel.

[0101] The obtained multifunctional flexible composite aerogel with electric-thermal deicing, anti-icing and microwave absorption has good block properties after drying, no cracking, and a density of 0.13g / cm 3 -0.25g / cm 3, and can return to its original shape after 1,000 times of compression and bending deformation; the flexible composite aerogel with electric-thermal deicing, anti-icing and microwave absorption has super-hydrophobic properties as a whole, and the contact angle is maintained above 153°; it has electric-thermal deicing and anti-icing properties in cold and humid environments, as well as excellent wave absorption properties.

[0102] Embodiment 7:

[0103] A method for preparing a multifunctional flexible composite aerogel with electric-thermal deicing, anti-icing and microwave absorption, comprising the following steps:

[0104] (1) mixing a surfactant and deionized water uniformly by mechanical stirring, adding a silicon source precursor to hydrolyze to obtain a silica sol after sufficient reaction, and the reaction is carried out at a constant temperature of 35° C.; the surfactant is hexadecyltrimethylammonium bromide, and the silicon source precursor is methyltrimethoxysilane; in terms of molar ratio, the molar ratio of surfactant: deionized water: silicon source precursor is 0.0002:2.2:0.15;

[0105] (2) adding diluted ammonia water to the sol obtained in step (1) to make the pH of the sol greater than 7, and then completely impregnating the sol into a nickel-copper polyurethane conductive sponge in a vacuum environment, and allowing the sol to stand after the impregnation to obtain a silicon dioxide composite wet gel; the amount of ammonia water added is ensured to be calculated in a molar ratio of ammonia water:silicon source precursor=0.002:0.12;

[0106] (3) aging the silica composite wet gel obtained in step (2) in a constant temperature environment of 35° C. for 12 h;

[0107] (4) performing solvent replacement of the silicon dioxide composite wet gel obtained in step (3) with anhydrous ethanol at 60° C. for 1 day;

[0108] (5) Drying the replaced silica composite wet gel obtained in step (4) at 90° C. under normal pressure to obtain a multifunctional flexible composite aerogel.

[0109] The obtained multifunctional flexible composite aerogel with electric-thermal deicing, anti-icing and microwave absorption has good block properties after drying, no cracking, and a density of 0.14g / cm 3 -0.27g / cm 3 , and can return to its original shape after 1,000 times of compression and bending deformation; the flexible composite aerogel with electro-thermal deicing, anti-icing and microwave absorption has super-hydrophobic properties as a whole, and the contact angle is maintained above 152°; it has electro-thermal deicing and anti-icing properties in cold and humid environments, as well as excellent wave absorption properties.

[0110] Embodiment 8:

[0111] A method for preparing a multifunctional flexible composite aerogel with electric-thermal deicing, anti-icing and microwave absorption, comprising the following steps:

[0112] (1) mixing a surfactant and deionized water uniformly by mechanical stirring, adding a silicon source precursor to hydrolyze to obtain a silica sol after sufficient reaction, and the reaction is carried out at a constant temperature of 35° C.; the surfactant is hexadecyltrimethylammonium bromide, and the silicon source precursor is methyltrimethoxysilane; in terms of molar ratio, the molar ratio of surfactant: deionized water: silicon source precursor is 0.0005:2.2:0.15;

[0113] (2) adding diluted ammonia water to the sol obtained in step (1) to make the pH of the sol greater than 7, and then completely impregnating the sol into a nickel-copper polyurethane conductive sponge in a vacuum environment, and allowing the sol to stand after the impregnation to obtain a silicon dioxide composite wet gel; the amount of ammonia water added is ensured to be calculated in a molar ratio of ammonia water:silicon source precursor=0.002:0.12;

[0114] (3) aging the silica composite wet gel obtained in step (2) in a constant temperature environment of 35° C. for 12 h;

[0115] (4) performing solvent replacement of the silicon dioxide composite wet gel obtained in step (3) with anhydrous ethanol at 60° C. for 1 day;

[0116] (5) Drying the replaced silica composite wet gel obtained in step (4) at 90° C. under normal pressure to obtain a multifunctional flexible composite aerogel.

[0117] The obtained multifunctional flexible composite aerogel with electric-thermal deicing, anti-icing and microwave absorption has good block properties after drying, no cracking, and a density of 0.13g / cm 3 -0.21g / cm 3 , and can return to its original shape after 1,000 times of compression and bending deformation; the flexible composite aerogel with electro-thermal deicing, anti-icing and microwave absorption has super-hydrophobic properties as a whole, and the contact angle is maintained above 150°; it has electro-thermal deicing and anti-icing properties in cold and humid environments, as well as excellent wave absorption properties.

[0118] Embodiment 9:

[0119] A method for preparing a multifunctional flexible composite aerogel with electric-thermal deicing, anti-icing and microwave absorption, comprising the following steps:

[0120] (1) mixing a surfactant and deionized water uniformly by mechanical stirring, adding a silicon source precursor to hydrolyze to obtain a silica sol after sufficient reaction, and the reaction is carried out at a constant temperature of 35° C.; the surfactant is hexadecyltrimethylammonium bromide, and the silicon source precursor is methyltrimethoxysilane; in terms of molar ratio, the molar ratio of surfactant: deionized water: silicon source precursor is 0.0008:2.4:0.12;

[0121] (2) adding diluted ammonia water to the sol obtained in step (1) to make the pH of the sol greater than 7, and then completely impregnating the sol into a nickel-copper polyurethane conductive sponge in a vacuum environment, and allowing the sol to stand after the impregnation to obtain a silicon dioxide composite wet gel; the amount of ammonia water added is ensured to be calculated in a molar ratio of ammonia water:silicon source precursor=0.002:0.12;

[0122] (3) aging the silica composite wet gel obtained in step (2) in a constant temperature environment of 35° C. for 12 h;

[0123] (4) performing solvent replacement of the silicon dioxide composite wet gel obtained in step (3) with anhydrous ethanol at 60° C. for 1 day;

[0124] (5) Drying the replaced silica composite wet gel obtained in step (4) at 90° C. under normal pressure to obtain a multifunctional flexible composite aerogel.

[0125] The obtained multifunctional flexible composite aerogel with electric-thermal deicing, anti-icing and microwave absorption has good block properties after drying, no cracking, and a density of 0.12g / cm 3 -0.28g / cm 3 , and can return to its original shape after 1,000 times of compression and bending deformation; the flexible composite aerogel with electro-thermal deicing, anti-icing and microwave absorption has super-hydrophobic properties as a whole, and the contact angle is maintained above 155°; it has electro-thermal deicing and anti-icing properties in cold and humid environments, as well as excellent wave absorption properties.

[0126] Embodiment 10:

[0127] A method for preparing a multifunctional flexible composite aerogel with electric-thermal deicing, anti-icing and microwave absorption, comprising the following steps:

[0128] (1) mixing a surfactant and deionized water uniformly by mechanical stirring, adding a silicon source precursor to hydrolyze to obtain a silica sol after sufficient reaction, and the reaction is carried out at a constant temperature of 35° C.; the surfactant is hexadecyltrimethylammonium bromide, and the silicon source precursor is methyltrimethoxysilane; in terms of molar ratio, the molar ratio of surfactant: deionized water: silicon source precursor is 0.0002:2.8:0.15;

[0129] (2) adding diluted ammonia water to the sol obtained in step (1) to make the pH of the sol greater than 7, and then completely impregnating the sol into a nickel-copper polyurethane conductive sponge in a vacuum environment, and allowing the sol to stand after the impregnation to obtain a silicon dioxide composite wet gel; the amount of ammonia water added is ensured to be calculated in a molar ratio of ammonia water:silicon source precursor=0.002:0.12;

[0130] (3) aging the silica composite wet gel obtained in step (2) in a constant temperature environment of 35° C. for 12 h;

[0131] (4) performing solvent replacement on the silicon dioxide composite wet gel obtained in step (3) with anhydrous ethanol at 60° C. for 1 day; and then performing solvent replacement at 80° C. for 1 day;

[0132] (5) Drying the replaced silica composite wet gel obtained in step (4) at 90° C. under normal pressure to obtain a multifunctional flexible composite aerogel.

[0133] The obtained multifunctional flexible composite aerogel with electric-thermal deicing, anti-icing and microwave absorption has good block properties after drying, no cracking, and a density of 0.14g / cm 3 -0.24g / cm 3 , and can return to its original shape after 1,000 compression and bending deformations; the flexible composite aerogel with electro-thermal deicing, anti-icing and microwave absorption has super-hydrophobic properties as a whole, and the contact angle is maintained above 154°; it has electro-thermal deicing and anti-icing properties in cold and humid environments, as well as excellent wave absorption properties.

[0134] Embodiment 11:

[0135] A method for preparing a multifunctional flexible composite aerogel with electric-thermal deicing, anti-icing and microwave absorption, comprising the following steps:

[0136] (1) mixing a surfactant and deionized water uniformly by mechanical stirring, adding a silicon source precursor to hydrolyze to obtain a silica sol after sufficient reaction, and the reaction is carried out at a constant temperature of 35° C.; the surfactant is hexadecyltrimethylammonium bromide, and the silicon source precursor is methyltrimethoxysilane; in terms of molar ratio, the molar ratio of surfactant: deionized water: silicon source precursor is 0.0005:2.5:0.18;

[0137] (2) adding diluted ammonia water to the sol obtained in step (1) to make the pH of the sol greater than 7, and then completely impregnating the sol into the carbon nanotube conductive polyurethane sponge in a vacuum environment, and letting it stand after the impregnation to obtain a silicon dioxide composite wet gel; the amount of ammonia water added is ensured to be calculated in a molar ratio of ammonia water: silicon source precursor = 0.002:0.12;

[0138] (3) aging the silica composite wet gel obtained in step (2) in a constant temperature environment of 35° C. for 16 h;

[0139] (4) performing solvent replacement on the silicon dioxide composite wet gel obtained in step (3) with anhydrous ethanol at 60° C. for 1 day; and then performing solvent replacement at 80° C. for 1 day;

[0140] (5) Drying the replaced silica composite wet gel obtained in step (4) at 90° C. under normal pressure to obtain a multifunctional flexible composite aerogel.

[0141] The obtained multifunctional flexible composite aerogel with electric-thermal deicing, anti-icing and microwave absorption has good block properties after drying, no cracking, and a density of 0.13g / cm 3 -0.28g / cm 3 , and can return to its original shape after 1,000 times of compression and bending deformation; the flexible composite aerogel with electro-thermal deicing, anti-icing and microwave absorption has super-hydrophobic properties as a whole, and the contact angle is maintained above 151°; it has electro-thermal deicing and anti-icing properties in cold and humid environments, as well as excellent wave absorption properties.

[0142] Embodiment 12:

[0143] A method for preparing a multifunctional flexible composite aerogel with electric-thermal deicing, anti-icing and microwave absorption, comprising the following steps:

[0144] (1) mixing a surfactant and deionized water uniformly by mechanical stirring, adding a silicon source precursor to hydrolyze to obtain a silica sol after sufficient reaction, and the reaction is carried out at a constant temperature of 35° C.; the surfactant is hexadecyltrimethylammonium chloride, and the silicon source precursor is methyltriethoxysilane; in terms of molar ratio, the molar ratio of surfactant: deionized water: silicon source precursor is 0.0008:2.0:0.21;

[0145] (2) adding diluted ammonia water to the sol obtained in step (1) to make the pH of the sol greater than 7, and then completely impregnating the sol into the porous magnetic metal foam in a vacuum environment, and allowing the sol to stand after the impregnation to obtain a silicon dioxide composite wet gel; the amount of ammonia water added is ensured to be calculated in a molar ratio of ammonia water: silicon source precursor = 0.002:0.12;

[0146] (3) aging the silica composite wet gel obtained in step (2) in a constant temperature environment of 35° C. for 24 h;

[0147] (4) performing solvent replacement on the silicon dioxide composite wet gel obtained in step (3) with anhydrous ethanol at 80° C. for 2 days; and then performing solvent replacement at 90° C. for 2 days;

[0148] (5) Drying the replaced silica composite wet gel obtained in step (4) at 90° C. under normal pressure to obtain a multifunctional flexible composite aerogel.

[0149] The obtained multifunctional flexible composite aerogel with electric-thermal deicing, anti-icing and microwave absorption has good block properties after drying, no cracking, and a density of 0.13g / cm 3 -0.22g / cm 3 , and can return to its original shape after 1,000 times of compression and bending deformation; the flexible composite aerogel with electro-thermal deicing, anti-icing and microwave absorption has super-hydrophobic properties as a whole, and the contact angle is maintained above 152°; it has electro-thermal deicing and anti-icing properties in cold and humid environments, as well as excellent wave absorption properties.

[0150] Comparative Example 1:

[0151] Comparative Example 1 is to explore the effect of aging temperature on the morphology change of aerogel after drying. The difference from Example 3 is that a replacement process is added to step (3). Comparative Example 1 is directly dried in an environment of 90°C after aging at room temperature and 35°C for 12h. The rest is the same as Example 3.

[0152] like Figure 8 As shown, the shrinkage rate of pure aerogel at different aging temperatures is shown. The shrinkage rate of pure aerogel will affect the structural stability and electro-thermal deicing, anti-icing and wave absorption properties of composite aerogel. Therefore, the shrinkage rate of the prepared pure aerogel must be zero to make the composite aerogel have a more reliable structure and performance. It can be seen that the aerogels prepared without replacement process all show a great shrinkage rate. The shrinkage rate after drying at room temperature is 9.4%, while the shrinkage rate after drying at 35°C is 8.0%.

[0153] The results show that by applying a constant temperature during the aging process, the shrinkage rate of pure aerogel can be promoted. This is mainly because the constant temperature facilitates the reinforcement of the skeleton during the aging process, thereby preventing the evaporation of water during the drying process from generating a large surface tension that affects the skeleton network. Aging at ambient temperature results in inconsistent temperature changes, and the reinforcement effect on the skeleton is limited. Therefore, the shrinkage rate after drying is greater than that of pure aerogel after aging at 35°C.

[0154] Comparative Example 2:

[0155] The difference between Comparative Example 2 and Example 3 is that the replacement temperature in step (4) is 50°C and 90°C, and the rest is the same as Example 3, except that the replacement temperature in Example 3 is changed to 70°C, which confirms that the replacement temperature is feasible at 60°C-80°C.

[0156] like Fig. 9 As shown, the shrinkage of the prepared aerogel after drying at replacement temperatures of 50°C and 90°C is 6.5% and 7.2%, respectively, while the shrinkage of the aerogel after drying at 70°C is 0%.

[0157] The results show that the replacement temperature is crucial to the shrinkage rate of pure aerogel. Shrinkage will still occur when replaced at 50°C, and there is still an improvement compared to no replacement, but the shrinkage rate cannot be completely solved. This is mainly because it is difficult to completely replace the water in the pores of pure aerogel at a temperature of 50°C, resulting in a large surface tension during the drying process, which leads to the shrinkage of pure aerogel. Shrinkage will still occur when replaced at 90°C, mainly because the solvent replaced at 90°C has reached a mild boiling phenomenon, which accelerates the replacement of water with the pores of pure aerogel. However, this process will cause structural damage to the skeleton of the pure aerogel, and the aerogel will shrink after drying. Maintaining the replacement temperature in the range of 60°C-80°C will not affect the skeleton of the pure aerogel while ensuring sufficient replacement, thereby achieving near-zero shrinkage of the aerogel and successfully preparing flexible composite aerogel.

[0158] Results and Discussion:

[0159] By comparing Example 3 with Comparative Examples 1 and 2, it is shown that the aging temperature and replacement temperature in step (3) and step (4) are very important, which greatly affects the shrinkage rate of the pure aerogel, and further affects the stability of the structure and performance of the composite aerogel. This unique aging and replacement method solves the shrinkage problem of the aerogel, which is also quite different from other inventions, so that the flexible composite aerogel has excellent electro-thermal deicing, anti-icing and microwave absorption properties while maintaining its structural stability.

[0160] The method for preparing a multifunctional flexible composite aerogel with electric-thermal deicing, anti-icing and microwave absorption described in the present invention is to use a strategy of synergistic enhancement of flexible conductive sponge and flexible silica aerogel to develop a multifunctional flexible composite aerogel with excellent structural stability, flexibility, tailorability and mechanical properties. Since the surface of silica aerogel is rich in a large number of methyl groups, the flexible composite aerogel has excellent superhydrophobic properties. In addition, the electrothermal effect of the conductive sponge and the thermal insulation performance of the aerogel make the flexible composite aerogel have deicing and anti-icing properties. In addition, the interface polarization between the aerogel and the conductive sponge skeleton makes the flexible composite aerogel have excellent microwave absorption characteristics. The technical solution proposed by the present invention fully integrates the advantages of the two materials, so that it has excellent mechanical properties while being easy to process and low-cost, and ensures the stable progress of ice melting, anti-icing and microwave absorption.

[0161] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present technical invention.

Claims

1. A method for preparing a multifunctional flexible composite aerogel with electric-thermal deicing, anti-icing and microwave absorption, characterized in that: The following steps are involved: (1) mixing a surfactant and deionized water in proportion, adding a silicon source precursor after sufficient reaction to completely hydrolyze the mixture to obtain a silica sol, and the reaction was carried out at a constant temperature of 35° C.; The molar ratio of the surfactant, deionized water and silicon source precursor is (0.0002-0.0008):(2-2.8):(0.12-0.21); The surfactant is hexadecyltrimethylammonium bromide or hexadecyltrimethylammonium chloride; The silicon source precursor is methyltrimethoxysilane or methyltriethoxysilane; (2) adding ammonia water to the silica sol obtained in step (1) to make the pH of the sol greater than 7, and then completely immersing the sol into a conductive sponge in a vacuum environment, and gelling and aging in an environment of 35° C. for 12 h to 24 h to obtain a conductive sponge-reinforced silica composite wet gel; The conductive sponge is one of nickel-copper polyurethane conductive sponge, porous magnetic metal foam or carbon nanotube conductive polyurethane sponge; (3) subjecting the conductive sponge-enhanced silica composite wet gel obtained in step (2) to solvent replacement, wherein the replacement solvent is n-hexane or anhydrous ethanol, the replacement time is 1 d to 2 d, and the replacement temperature is 60° C. to 80° C.; (4) drying the conductive sponge-reinforced silica composite wet gel obtained by substitution in step (3) under normal pressure at a drying temperature of 80° C. to 90° C. for a drying time of 1 to 2 days to obtain a multifunctional flexible composite aerogel having electric-thermal deicing, anti-icing and microwave absorption. The typical properties of the prepared multifunctional flexible composite aerogel having electric-thermal deicing, anti-icing and microwave absorption are as follows: ① The multifunctional flexible composite aerogel has excellent mechanical properties, good block properties after drying, no cracking, and a density of 0.11g / cm 3 -0.28g / cm 3 , after 1000 times of compression and bending deformation, it can recover to its original shape; ② The multifunctional flexible composite aerogel has super hydrophobic properties as a whole, and the contact angle is maintained at 150°-155°; ③ The multifunctional flexible composite aerogel has electric-thermal deicing and anti-icing properties in cold and humid environments, has excellent electric-thermal conversion effect and excellent thermal insulation performance, can quickly melt frozen water droplets, and delays freezing time by 1500s in an environment of -20°C; ④ The multifunctional flexible composite aerogel has excellent electromagnetic wave absorption properties, wherein the three-dimensional structure constructs a double interface polarization, so that the minimum reflection loss of the flexible composite aerogel at a thickness of 2.2 mm reaches -19.07 dB, and the absorption bandwidth reaches 8.24 GHz.

2. The method for preparing a multifunctional flexible composite aerogel with electric-thermal deicing, anti-icing and microwave absorption according to claim 1, characterized in that: The surfactant described in step (1) is hexadecyltrimethylammonium bromide.

3. The method for preparing a multifunctional flexible composite aerogel with electric-thermal deicing, anti-icing and microwave absorption according to claim 1, characterized in that: The silicon source precursor described in step (1) is methyltrimethoxysilane.

4. The method for preparing a multifunctional flexible composite aerogel with electric-thermal deicing, anti-icing and microwave absorption according to claim 1, characterized in that: The gelation and aging process in step (2) is performed for 12 hours.

5. The method for preparing a multifunctional flexible composite aerogel with electric-thermal deicing, anti-icing and microwave absorption according to claim 1, characterized in that: The conductive sponge described in step (2) is a nickel-copper polyurethane conductive sponge.

6. The method for preparing a multifunctional flexible composite aerogel with electric-thermal deicing, anti-icing and microwave absorption according to claim 1, characterized in that: In the solvent replacement described in step (3), the replacement solvent is n-hexane, the replacement time is 1 day, and the replacement temperature is 60°C.

7. A multifunctional flexible composite aerogel with electro-thermal deicing, anti-icing and microwave absorption, characterized in that: The multifunctional flexible composite aerogel having electric-thermal deicing, anti-icing and microwave absorption is prepared by the method for preparing the multifunctional flexible composite aerogel having electric-thermal deicing, anti-icing and microwave absorption according to any one of claims 1 to 6. The typical properties of the prepared multifunctional flexible composite aerogel having electric-thermal deicing, anti-icing and microwave absorption are: ① The multifunctional flexible composite aerogel has excellent mechanical properties, good block properties after drying, no cracking, and a density of 0.11g / cm 3 -0.28g / cm 3 , after 1000 times of compression and bending deformation, it can recover to its original shape; ② The multifunctional flexible composite aerogel has super hydrophobic properties as a whole, and the contact angle is maintained at 150°-155°; ③ The multifunctional flexible composite aerogel has electric-thermal deicing and anti-icing properties in cold and humid environments, has excellent electric-thermal conversion effect and excellent thermal insulation performance, can quickly melt frozen water droplets, and delays freezing time by 1500s in an environment of -20°C; ④ The multifunctional flexible composite aerogel has excellent electromagnetic wave absorption properties, wherein the three-dimensional structure constructs a double interface polarization, so that the minimum reflection loss of the flexible composite aerogel at a thickness of 2.2 mm reaches -19.07 dB, and the absorption bandwidth reaches 8.24 GHz.

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