Impact-resistant flame-retardant gel material and preparation method thereof

Abstract

The invention belongs to the field of materials, and particularly relates to an impact-resistant flame-retardant gas gel material and a preparation method thereof. The invention aims to solve the problems that the protective material is light in weight, and impact resistance and flame retardance are difficult to consider at the same time. The preparation method comprises the following steps: (1) preparing a chitosan-organic acid solution; (2) adding sodium tripolyphosphate, and preparing bi-crosslinked chitosan aerogel by using an ice crystal template method; (3) mixing high-viscosity polydimethylsiloxane and low-viscosity polydimethylsiloxane; (4) adding boric acid to prepare shear hardening gel; and (5) performing ultrasonic impregnation and drying to obtain the product. And the obtained product is light in weight, excellent in impact resistance (the impact peak force of a falling ball of 80cm is less than or equal to 580N), capable of self-extinguishing, and suitable for the high-end engineering fields such as aerospace, national defense and military, electronic and electrical appliances, new energy and the like.

Description

Technical Field

[0001] This invention belongs to the field of materials, specifically relating to an impact-resistant and flame-retardant gel material and its preparation method. Background Technology

[0002] In high-end engineering fields such as aerospace, national defense, electronics and new energy, protective materials need to cope with multiple extreme working conditions at the same time, and their performance requirements present a dual challenge of "multi-functional synergy" and "ultimate lightweight".

[0003] In the aerospace field, spacecraft must withstand not only the instantaneous mechanical impact during launch and the continuous heat flux during orbital operation, but also strictly control structural weight to reduce propulsion energy consumption—for example, every 1g increase in the weight of protective materials for satellite components can lead to an increase in launch costs. While traditional metal protective materials have excellent impact resistance, their high density makes it difficult to meet weight reduction requirements; pure SiO2 aerogel, although lightweight and with good thermal insulation, is brittle and lacks compressive strength, making it prone to breakage and failure under impact.

[0004] In the field of electronics and electrical appliances, there is a contradiction between "miniaturization" and "safety": as the integration of components such as chips and power batteries increases, the local high temperatures generated during their operation require protective materials that are both flame-retardant and heat dissipation compatible, while also needing to withstand accidental drops during transportation or use (such as preventing laptop batteries from shattering and catching fire when dropped). Traditional flame-retardant materials, such as halogenated flame retardants, are highly efficient, but they release toxic gases when burning and reduce the mechanical properties of the substrate; while single shear-hardening materials (such as pure polysiloxane alkyl gels) can respond to impacts through dynamic bonds, their poor formability and high density make them difficult to adapt to the lightweight and precision packaging requirements of electronic components.

[0005] In the defense and military field, individual protective equipment (such as helmet liners) and armored vehicle buffer layers need to maintain stable performance under extreme temperature and humidity conditions. They must withstand the instantaneous impact of shrapnel or blast shock waves, and also possess a certain degree of flame retardancy to cope with open flame environments on the battlefield. Existing composite protective materials mostly adopt a "metal skeleton + organic filler" structure, which is complex in process and difficult to control in terms of weight. While pure biomass aerogels (such as unmodified chitosan aerogels) are environmentally friendly and lightweight, their low degree of cross-linking and disordered pore structure result in impact resistance and flame retardancy that cannot meet the requirements of harsh scenarios.

[0006] In addition, the existing preparation processes for multifunctional protective materials generally have bottlenecks: some processes rely on high-temperature sintering (>500℃) or toxic solvents (such as toluene and formaldehyde), which not only consumes a lot of energy and pollutes the environment, but also easily damages the microporous structure of the material, leading to performance imbalance; while the traditional impregnation method requires long-term soaking (>12h), which is inefficient and prone to uneven impregnation, making it difficult to achieve large-scale production.

[0007] In summary, there is an urgent need to develop a multifunctional protective material that is ultra-lightweight, highly impact-resistant, and has excellent flame retardancy, and whose manufacturing process is environmentally friendly and efficient, in order to resolve the contradiction between the protection needs in multiple fields and the shortcomings of existing materials. Summary of the Invention

[0008] To address the problems existing in the prior art, the present invention provides a method for preparing an impact-resistant and flame-retardant gel material, the method comprising the following steps:

[0009] (1) Add chitosan to the organic acid solution and stir until homogeneous to obtain a chitosan-organic acid solution;

[0010] (2) Add sodium tripolyphosphate solution to the chitosan-organic acid solution, stir evenly and react, and then prepare a flame-retardant double crosslinked chitosan composite aerogel by the ice crystal template method;

[0011] (3) Mix and stir high-viscosity polydimethylsiloxane and low-viscosity polydimethylsiloxane to obtain mixed polydimethylsiloxane;

[0012] (4) Add boric acid materials to the mixed polydimethylsiloxane and stir to react, then cool under vacuum to obtain shear-hardened gel;

[0013] (5) The double cross-linked chitosan composite aerogel is placed in the solvent dispersion of shear hardening gel, ultrasonically impregnated and then dried to obtain the impact-resistant and flame-retardant gel material.

[0014] Preferably, in step (1), the organic acid is one or a combination of two or more of monocarboxylic acids, dicarboxylic acids, and tricarboxylic acids; wherein:

[0015] The monocarboxylic acid is acetic acid, the dicarboxylic acid is itaconic acid, and the tricarboxylic acid is citric acid.

[0016] Preferably, in step (1), the concentration of the organic acid solution is 0.02-0.05 g / mL;

[0017] And / or, in the chitosan-organic acid solution, the concentration of chitosan is 0.01-0.06 g / mL.

[0018] Preferably, in step (2), the concentration of the sodium tripolyphosphate solution is 0.05-0.15 mol / L.

[0019] Preferably, in step (2), the ice crystal template method is: rapid freezing for 20-40 minutes under conditions of -60 to -40°C followed by vacuum freeze drying.

[0020] Preferably, in step (3), the high-viscosity polydimethylsiloxane is a hydroxyl-terminated polydimethylsiloxane with a viscosity of 15,000-28,000 cSt; the low-viscosity polydimethylsiloxane is a hydroxyl-terminated polydimethylsiloxane with a viscosity of 30-100 cSt.

[0021] And / or, the mass ratio of the mixture is 1:1.

[0022] Preferably, in step (4), the boric acid material is one or a combination of two or more of tetrahydroxydiboron, phenylboronic acid, and boric acid;

[0023] And / or, the temperature of the stirring reaction is 80-95℃, and the time is 2-3h;

[0024] And / or, the vacuum cooling time is 20-24 hours.

[0025] Preferably, in step (5), the concentration of the solvent dispersion for shear hardening gel is 60-150 g / L;

[0026] And / or, the solvent is acetone or anhydrous ethanol;

[0027] And / or, the ultrasonic-assisted impregnation time is 2-6 hours;

[0028] And / or, the drying temperature is 80~95℃, and the drying time is 8-24h.

[0029] Based on the same technical concept, another aspect of the present invention is to provide an impact-resistant and flame-retardant gel material obtained by the above preparation method.

[0030] The beneficial effects of this invention are as follows:

[0031] The impact-resistant and flame-retardant aerogel material and its preparation method provided by this invention, through the innovative process of "double cross-linked chitosan aerogel matrix construction - shear-hardening gel ultrasonic impregnation composite", effectively solves the core problems of existing protective materials such as "difficulty in balancing lightweight and impact resistance, easy imbalance between flame retardancy and mechanical properties, and complex and environmentally unfriendly processes" from the two dimensions of material structure design and preparation process optimization. Finally, a multifunctional composite aerogel with ultra-lightweight, high compressive strength, excellent impact resistance and efficient flame retardancy is obtained. Moreover, the preparation process is green and low-consumption, easy to scale up, and can be widely adapted to the protection needs of aerospace, electronics, defense and military and other fields.

[0032] 1. Achieve synergistic improvement in "mechanical properties and flame retardant properties," solving the problem of performance imbalance in traditional materials:

[0033] This invention constructs a chitosan composite aerogel using a dual crosslinking strategy: organic acids (such as itaconic acid) form primary crosslinks with chitosan, while phosphate groups in sodium tripolyphosphate form secondary crosslinks with chitosan amino groups. This optimizes the regularity of the pore structure and imparts intrinsic flame retardancy to the matrix through phosphate groups. Combined with a shear-hardening gel introduced by ultrasonic-assisted impregnation, its unique boron-oxygen dynamic bonds rapidly increase the modulus with increasing external strain rate, significantly enhancing impact resistance. Verification data shows that the product of this invention exhibits a peak force of only 546.66~578.78 N under an 80cm falling ball impact (compared to 3556.59 N for the blank sample), with a force decay rate exceeding 84%. Furthermore, it is self-extinguishing under alcohol torch burning (flame burning time is 0), perfectly solving the pain points of traditional aerogels being "brittle" and flame-retardant modifications reducing mechanical strength.

[0034] 2. Maintaining ultra-lightweight characteristics, precisely matching the weight reduction needs of high-end fields:

[0035] This invention uses the ice crystal template method to prepare chitosan aerogel. The composite process only introduces low-density shear-hardening gel through ultrasonic impregnation, without adding heavy components (such as metal particles or inorganic fillers). The final product has a low density, which meets the weight reduction requirements of aerospace. At the same time, the regular porous structure can also help dissipate heat, which is suitable for the thermal management needs of electronic and electrical components, and solves the limitations of traditional metal protective materials being "heavy" and pure shear-hardening materials being "high-density".

[0036] 3. The preparation process is environmentally friendly and efficient, lowering the threshold for industrialization:

[0037] This invention utilizes inexpensive and non-toxic reagents such as chitosan (a bio-based, biodegradable raw material), organic acids, and sodium tripolyphosphate, avoiding the use of toxic solvents and high-temperature, high-energy-consumption processes. Rapid cooling (-60~-40℃, 20-40min) replaces high-temperature sintering, and ultrasonic-assisted impregnation (2-6h) shortens the traditional impregnation time by more than 60%. The drying temperature is only 80~95℃ (energy consumption reduced by 40%). The entire process produces no pollutants, is simple in steps, has low equipment dependence, and can achieve continuous production, solving the industrialization bottleneck of existing processes characterized by "high consumption, pollution, and low efficiency."

[0038] 4. Highly adjustable performance, adaptable to diverse needs across multiple fields.

[0039] This invention allows for flexible adjustment of product performance by regulating key process parameters: for example, changing the sodium tripolyphosphate concentration (0.05~0.15mol / L) can optimize the aerogel crosslinking degree to adapt to the mechanical requirements of different scenarios; selecting different borate materials (such as tetrahydroxydiboron, boric acid) can adjust the dynamic bond response speed of the shear-hardening gel to meet the differentiated impact resistance requirements of aerospace (high strain rate impact) and electronics (low strain rate drop). This adjustability allows the product to be adapted to multiple fields without significant process adjustments, significantly improving the versatility of the technology. Attached Figure Description

[0040] 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 of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 This is an optical photograph of the CIT and host-guest chitosan composite aerogel.

[0042] Figure 2 The curves showing the force versus time relationship and the corresponding peak impact force diagrams of the CIT and host-guest chitosan composite aerogel during the impact resistance process at different ball drop heights are shown.

[0043] Figure 3 It is a diagram of a compression mechanics test.

[0044] Figure 4 This is a comparison test diagram of pre-combustion. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0046] Example 1

[0047] This embodiment provides a method for preparing an impact-resistant, flame-retardant gel material, the method comprising the following steps:

[0048] (1) At room temperature, add 2g of chitosan (CS) to a 0.04g / mL itaconic acid (IA) aqueous solution and stir at a constant speed for 4 hours until the chitosan is completely dissolved to form a uniform light yellow solution.

[0049] (2) Add 4 mL of 0.15 mol / L sodium tripolyphosphate solution (TPP) to the above-mentioned acidic chitosan solution, stir evenly at room temperature for 3 hours, pour the resulting mixed solution into a mold, let it stand, and then quickly freeze it (freeze rapidly at -60℃ for 20 min). After that, freeze-dry the sample under vacuum for 72 hours to obtain chitosan composite aerogel (CIT).

[0050] (3) The hydroxyl-terminated polydimethylsiloxane with mixed viscosity was prepared by mechanical stirring of high viscosity (15000-28000 cSt) and low viscosity (30-100 cSt) in a mass ratio of 1:1;

[0051] (4) Add 40 mL of 25 g / L B2H4O4 methanol solution to 100 g of hydroxyl-terminated polydimethylsiloxane of mixed viscosity, heat to 80 °C and mechanically stir for 4 hours, then vacuum cool to obtain a shear hardening gel containing a diboron structure.

[0052] (5) The prepared CIT aerogel is placed in 100 g / L diboron structure shear hardening gel / ethanol dispersion, and after ultrasonic-assisted impregnation for 3 hours, it is placed in an 80℃ oven for drying for 12 hours to obtain the impact-resistant and flame-retardant gel material.

[0053] Example 2

[0054] This embodiment provides a method for preparing an impact-resistant, flame-retardant gel material, the method comprising the following steps:

[0055] (1) At room temperature, add 2g of chitosan (CS) to a 0.04g / mL itaconic acid (IA) aqueous solution and stir at a constant speed for 4 hours until the chitosan is completely dissolved to form a uniform light yellow solution.

[0056] (2) Add 4 mL of 0.15 mol / L sodium tripolyphosphate solution (TPP) to the above-mentioned acidic chitosan solution, stir evenly at room temperature for 3 hours, pour the resulting mixed solution into a mold, let it stand, and then quickly freeze it. After that, freeze-dry the sample under vacuum for 72 hours to obtain chitosan composite aerogel (CIT).

[0057] (3) The hydroxyl-terminated polydimethylsiloxane with mixed viscosity was prepared by mechanical stirring of high viscosity (15000-28000 cSt) and low viscosity (30-100 cSt) in a mass ratio of 1:1;

[0058] (4) Add 40 mL of 25 g / L H3BO3 methanol solution to 100 g of hydroxyl-terminated polydimethylsiloxane with mixed viscosity, heat to 80 °C and mechanically stir for 4 hours, then vacuum cool to obtain shear hardening gel containing a single boron structure.

[0059] (5) The prepared CIT aerogel is placed in 100 g / L single boron structure shear hardening gel / ethanol dispersion, and after ultrasonic-assisted impregnation for 3 hours, it is placed in an 80℃ oven to dry for 12 hours to obtain the impact-resistant and flame-retardant gel material.

[0060] Example 3

[0061] This embodiment provides a method for preparing an impact-resistant, flame-retardant gel material, the method comprising the following steps:

[0062] (1) At room temperature, add 2g of chitosan (CS) to a 0.04g / mL itaconic acid (IA) aqueous solution and stir at a constant speed for 4 hours until the chitosan is completely dissolved to form a uniform light yellow solution.

[0063] (2) Add 4 mL of 0.05 mol / L sodium tripolyphosphate solution (TPP) to the above-mentioned acidic chitosan solution, stir evenly at room temperature for 3 hours, pour the resulting mixed solution into a mold, let it stand and then quickly freeze it. After that, freeze-dry the sample under vacuum for 72 hours to obtain chitosan composite aerogel (CIT).

[0064] (3) The hydroxyl-terminated polydimethylsiloxane with mixed viscosity was prepared by mechanical stirring of high viscosity (15000-28000 cSt) and low viscosity (30-100 cSt) in a mass ratio of 1:1;

[0065] (4) Add 40 mL of 25 g / L B2H4O4 methanol solution to 100 g of hydroxyl-terminated polydimethylsiloxane of mixed viscosity, heat to 80 °C and mechanically stir for 4 hours, then vacuum cool to obtain a shear hardening gel containing a diboron structure.

[0066] (5) The prepared CIT aerogel is placed in 100 g / L diboron structure shear hardening gel / ethanol dispersion, and after ultrasonic-assisted impregnation for 3 hours, it is placed in an 80℃ oven for drying for 12 hours to obtain the impact-resistant and flame-retardant gel material.

[0067] Example 4

[0068] This embodiment provides a method for preparing an impact-resistant, flame-retardant gel material, the method comprising the following steps:

[0069] (1) At room temperature, add 2g of chitosan (CS) to a 0.04g / mL itaconic acid (IA) aqueous solution and stir at a constant speed for 4 hours until the chitosan is completely dissolved to form a uniform light yellow solution.

[0070] (2) Add 4 mL of 0.05 mol / L sodium tripolyphosphate solution (TPP) to the above-mentioned acidic chitosan solution, stir evenly at room temperature for 3 hours, pour the resulting mixed solution into a mold, let it stand and then quickly freeze it. After that, freeze-dry the sample under vacuum for 72 hours to obtain chitosan composite aerogel (CIT).

[0071] (3) The hydroxyl-terminated polydimethylsiloxane with mixed viscosity was prepared by mechanical stirring of high viscosity (15000-28000 cSt) and low viscosity (30-100 cSt) in a mass ratio of 1:1;

[0072] (4) Add 40 mL of 25 g / L H3BO3 methanol solution to 100 g of hydroxyl-terminated polydimethylsiloxane with mixed viscosity, heat to 80 °C and mechanically stir for 4 hours, then vacuum cool to obtain shear hardening gel containing a single boron structure.

[0073] (5) The prepared CIT aerogel is placed in 100 g / L single boron structure shear hardening gel / ethanol dispersion, and after ultrasonic-assisted impregnation for 3 hours, it is placed in an 80℃ oven to dry for 12 hours to obtain the impact-resistant and flame-retardant gel material.

[0074] Comparative Example 1

[0075] (1) At room temperature, add 2g of chitosan (CS) to a 0.04g / mL itaconic acid (IA) aqueous solution and stir at a constant speed for 4 hours until the chitosan is completely dissolved to form a uniform light yellow solution.

[0076] (2) After adding 4 mL of 0.15 mol / L sodium tripolyphosphate solution (TPP) to the above-mentioned acidic chitosan solution, stir evenly at room temperature for 3 hours, pour the resulting mixed solution into a mold, let it stand, and then quickly freeze it. After vacuum freeze-drying the sample for 72 hours, chitosan composite aerogel material (CIT) can be obtained.

[0077] Comparative Example 2

[0078] (1) At room temperature, add 2g of chitosan (CS) to a 0.04g / mL itaconic acid (IA) aqueous solution and stir at a constant speed for 4 hours until the chitosan is completely dissolved to form a uniform light yellow solution.

[0079] (2) After adding 4 mL of 0.05 mol / L sodium tripolyphosphate solution (TPP) to the above-mentioned acidic chitosan solution, stir evenly at room temperature for 3 hours, pour the resulting mixed solution into a mold, let it stand, and then quickly freeze it. After vacuum freeze-drying the sample for 72 hours, chitosan composite aerogel material (CIT) can be obtained.

[0080] Verification Example

[0081] Materials from Examples 1-4 and Comparative Examples 1-2 were used, with a sample size of Ф30×3 mm, and were tested. The test results are shown in Table 1.

[0082] Table 1

[0083]

[0084] To investigate the impact resistance of this protective material, a 12g falling ball impact test was conducted at heights of 80, 70, 60, and 50 cm using a falling ball impact testing device equipped with a force sensor. In this test, the blank sample was used where the falling ball directly contacted the force sensor, while the other test samples (Ф30×3 mm) served as buffer material placed on the force sensor. Table 1 shows that when there is no buffer material on the force sensor (i.e., the blank sample), the detected force increases instantaneously upon impact with the steel ball. In contrast, with the buffer material, the maximum force transmitted after the steel ball impacts the surface decreases significantly. At a height of 80 cm, the peak impact forces of Comparative Example 1 (954.93 N) and Comparative Example 2 (925.32 N) are similar, but Comparative Example 2, using the buffer material, exhibits a higher force attenuation rate. This indicates that when the concentration of sodium tripolyphosphate and itaconic acid crosslinking agent is appropriate, the aerogel structure exhibits greater strength. At the same concentration ratio of sodium tripolyphosphate to itaconic acid crosslinking agent, Examples 1 and 3, which underwent ultrasonic-assisted impregnation of the diboron-oxygen bond structure, exhibited superior impact resistance compared to Examples 2 and 4, which underwent monoboron-oxygen bond structure. This indicates that the shear hardening behavior of the supramolecular network of the diboron-oxygen bond structure is closer to that of a solid state, based on the stronger electron deficiency of boron atoms in the diboron structure and the presence of more coordination states and higher bond energies in the diboron-oxygen coordination bonds. Compared to the blank sample, the peak impact force of Example 3 at heights of 80, 70, 60, and 50 cm decreased by 84.6%, 85.4%, 86.0%, and 89.1%, respectively. Pre-flame retardant tests using an alcohol lamp revealed that, compared to the unimpregnated Comparative Examples 1 and 2, the host-guest chitosan composite aerogels (Examples 1-4) after ultrasonic-assisted impregnation all exhibited self-extinguishing properties after 10 seconds of combustion, demonstrating good flame retardant performance.

[0085] Furthermore, Figure 1 a is an optical photograph of CIT aerogel. Figure 1 b is an optical photograph of the host-guest chitosan composite aerogel after ultrasonic-assisted impregnation, shear hardening, and drying of the CIT aerogel dispersion.

[0086] Figure 2 CIT aerogels prepared with a suitable concentration ratio of itaconic acid / sodium tripolyphosphate dual crosslinking agent, and the force-time relationship curves of the host-guest chitosan composite aerogels after ultrasonic-assisted impregnation and shear hardening aerogels ( Figure 2 ae) and related peak impact force diagrams ( Figure 2 f). Using a falling ball impact test device equipped with a mechanical sensor, a 12g iron ball was dropped freely from a specified height (80, 70, 60 and 50 cm) to study the impact resistance of the host and guest chitosan composite aerogel. Figure 2'a' indicates that during the impact process, the sample achieves impact resistance by attenuating the peak force and extending the buffer time. Therefore, we evaluate the material's impact resistance by measuring the attenuation of the first peak force transmitted through the sensor and the change in the buffer time. Figure 2 be and Figure 2 As shown in f, as the height increases from 50cm to 80cm, the peak impact force of the blank sample increases significantly from 2947.65N to 3556.59N, indicating severe damage. Taking an 80cm drop height as an example, compared to the blank sample (3556.59N / 0.042ms), the peak impact force of CIT is 925.32N, with a decay rate of 73.98% and a buffer time extended to 0.134ms. This is because CIT has limited mechanical strength, and the aerogel structure deforms and collapses under impact load, dissipating some impact energy and thus reducing the peak force to some extent. With the introduction of diboron-containing shear-hardening gel, its unique diboron-oxygen dynamic bonds exhibit effective buffering characteristics. Compared to the blank sample, the host-guest chitosan composite aerogel shows an 84.6% decay rate in peak impact force at an 80cm drop height, and a buffer time extended to 0.184ms. Compared with CIT, the host-guest chitosan composite aerogel exhibits significantly improved impact resistance. This is attributed to the fact that the diboron-containing shear-hardening gel enhances the strength of the aerogel matrix structure, making the skeleton less prone to deformation. At the same time, it releases more energy during buckling to delay the densification process and reduce the degree of skeleton damage.

[0087] Figure 3 CIT aerogel prepared with a suitable concentration ratio of itaconic acid / sodium tripolyphosphate dual crosslinking agent, and compression test diagrams of the host-guest chitosan composite aerogel after ultrasonic-assisted impregnation and shear hardening. The load / strain curves ( Figure 3 a) and maximum compressive force ( Figure 3 (b) It can be seen that the compression performance of the host-guest chitosan composite aerogel is effectively improved compared to CIT.

[0088] Figure 4 A preliminary alcohol lamp combustion experiment was conducted on CIT aerogels prepared with a suitable concentration ratio of itaconic acid / sodium tripolyphosphate dual crosslinking agent, and on the host-guest chitosan composite aerogels after ultrasonic-assisted impregnation and shear hardening. CIT aerogels self-extinguished after burning for 3 seconds following a 10-second combustion period. Figure 4 a), while the host-guest chitosan composite aerogel exhibited immediate self-extinguishing after 10 seconds of combustion ( Figure 4 b). This indicates that the abundant Si-O-Si structure in the impregnated shear-hardening aerogel can effectively improve the flame retardancy of the composite material.

[0089] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing an impact-resistant and flame-retardant gel material, characterized in that, The preparation method includes the following steps: (1) Add chitosan to the organic acid solution and stir until homogeneous to obtain a chitosan-organic acid solution; (2) Add sodium tripolyphosphate solution to the chitosan-organic acid solution, stir evenly and react, and then prepare a flame-retardant double crosslinked chitosan composite aerogel by the ice crystal template method; (3) Mix and stir high-viscosity polydimethylsiloxane and low-viscosity polydimethylsiloxane to obtain mixed polydimethylsiloxane; (4) Add boric acid materials to the mixed polydimethylsiloxane and stir to react, then cool under vacuum to obtain shear-hardened gel; (5) The double cross-linked chitosan composite aerogel is placed in the solvent dispersion of shear hardening gel, ultrasonically impregnated and then dried to obtain the impact-resistant and flame-retardant gel material.

2. The method for preparing the impact-resistant and flame-retardant gel material according to claim 1, characterized in that, In step (1), the organic acid is one or a combination of two or more of monocarboxylic acids, dicarboxylic acids, and tricarboxylic acids; wherein: The monocarboxylic acid is acetic acid, the dicarboxylic acid is itaconic acid, and the tricarboxylic acid is citric acid.

3. The method for preparing the impact-resistant and flame-retardant gel material according to claim 1, characterized in that, In step (1), the concentration of the organic acid solution is 0.02-0.05 g / mL; And / or, in the chitosan-organic acid solution, the concentration of chitosan is 0.01-0.06 g / mL.

4. The method for preparing the impact-resistant and flame-retardant gel material according to claim 1, characterized in that, In step (2), the concentration of the sodium tripolyphosphate solution is 0.05-0.15 mol / L.

5. The method for preparing the impact-resistant and flame-retardant gel material according to claim 1, characterized in that, In step (2), the ice crystal template method is: rapid freezing for 20-40 minutes under conditions of -60 to -40℃ followed by vacuum freeze drying.

6. The method for preparing the impact-resistant and flame-retardant gel material according to claim 1, characterized in that, In step (3), the high-viscosity polydimethylsiloxane is: hydroxyl-terminated polydimethylsiloxane with a viscosity of 15000-28000 cSt; the low-viscosity polydimethylsiloxane is: hydroxyl-terminated polydimethylsiloxane with a viscosity of 30-100 cSt. And / or, the mass ratio of the mixture is 1:

1.

7. The method for preparing the impact-resistant and flame-retardant gel material according to claim 1, characterized in that, In step (4), the boric acid material is one or a combination of two or more of tetrahydroxydiboron, phenylboronic acid, and boric acid; And / or, the temperature of the stirring reaction is 80-95℃, and the time is 2-3h; And / or, the vacuum cooling time is 20-24 hours.

8. The method for preparing the impact-resistant and flame-retardant gel material according to claim 1, characterized in that, In step (5), the concentration of the solvent dispersion for shear hardening gel is 60-150 g / L; And / or, the solvent is acetone or anhydrous ethanol; And / or, the ultrasonic-assisted impregnation time is 2-6 hours; And / or, the drying temperature is 80~95℃, and the drying time is 8-24h.

9. The impact-resistant and flame-retardant gel material obtained by the preparation method according to any one of claims 1-8.

Images