Triple-period minimal curved surface structure-modified nanocellulose aerogel composite thermal insulation material and preparation method thereof

Abstract

The invention relates to the field of high-performance composite thermal insulation materials, in particular to a three-period minimal curved surface-MTMS modified nano cellulose aerogel composite thermal insulation material. The composite thermal insulation material is composed of a main body framework and a filling phase, and the main body framework is a surface-hydroxylated three-period minimal curved surface framework; and the filling phase is a silane modified carboxylated nano cellulose aerogel. The composite thermal insulation material disclosed by the invention is excellent in comprehensive performance and has excellent thermal insulation performance, mechanical performance and water resistance; the heat conductivity coefficient is 0.020-0.03 W / (m.K), the compression strength reaches 1.0-1.5 MPa, the water contact angle is larger than 90 degrees, and multi-scene application is met. The material is simple in preparation method and convenient in structure regulation and control; the material has wide application prospects in spaceflight, military protection equipment, precise instrument heat insulation and other scenes.

Description

Technical Field

[0001] This invention relates to the field of high-performance composite thermal insulation materials, specifically to a three-period minimal curved surface-MTMS modified nanocellulose aerogel composite thermal insulation material. Background Technology

[0002] With the development of fields such as building energy conservation, cold chain logistics, and spacecraft thermal protection, the performance requirements for lightweight and high-efficiency thermal insulation materials are becoming increasingly stringent. Traditional thermal insulation materials, such as polyurethane foam and fiberglass mat, are finding it increasingly difficult to simultaneously achieve "low thermal conductivity (λ < 0.030 W / m⁻)". 1 K -1 "Low density (ρ < 50 mg / cm³)" -3 The three requirements are "environmentally friendly" and "environmentally friendly".

[0003] Nanocellulose, as an important natural polymer and novel nanomaterial, possesses high mechanical properties, low density, good biocompatibility, biodegradability, and nanostructure effects, making it widely used in composite reinforcement materials, biomedicine, chemical industry, and food. Nanocellulose aerogel exhibits excellent thermal insulation properties (thermal conductivity as low as 0.02-0.04 W / (mK)) and high porosity (80%-95%), but its mechanical properties are poor, it is brittle, and easily breaks under load or repeated impact. Furthermore, it has strong hydrophilicity, absorbing large amounts of moisture in humid environments, leading to a decline or failure of its thermal insulation performance, thus limiting its application in structural load-bearing scenarios. In existing technologies, when using nanocellulose aerogel as a thermal insulation material, porous support materials such as polyurethane foam or metal honeycomb are usually introduced to compensate for the mechanical shortcomings of aerogel. However, although porous support materials can provide certain mechanical support, they have high thermal conductivity (such as polyurethane foam with a thermal conductivity of about 0.025-0.04 W / (mK)) and disordered pore structure, which cannot form a synergistic thermal insulation effect with aerogel.

[0004] Triple-periodic minimal surfaces (TPMS) are a class of three-dimensional surface structures with mathematical periodicity. Common TPMS structures include Gyroid (G-surface), Diamond (D-surface), Primitive (P-surface), and I-WP surfaces, which have uniformly interconnected pores, high specific strength, and designability. However, the thermal insulation performance of pure TPMS structures depends on the air layer, resulting in convective heat transfer problems and making it difficult to further reduce the thermal conductivity (typically >0.05 W / (mK)). TPMS structures primarily optimize the material's "geometry," but their final thermal insulation performance still strongly depends on the thermophysical properties of the matrix material itself. Furthermore, printed polymer TPMS structures have poor temperature resistance; while ceramic TPMS structures are prone to shrinkage and cracking during sintering, leading to deviations between the actual structure and the design model, affecting performance. This also limits the application of TPMS in thermal insulation materials.

[0005] Therefore, it is necessary to develop a new high-performance thermal insulation material. Summary of the Invention

[0006] To address the aforementioned problems in the existing technology, this invention provides a hydrophobic composite thermal insulation material that achieves ultra-low thermal conductivity and provides reliable structural support, as well as a method for its preparation.

[0007] The first objective of this invention is to provide a composite thermal insulation material, which consists of a main skeleton and a filling phase, wherein the main skeleton is a three-period minimal curved surface and the filling phase is nanocellulose aerogel.

[0008] Furthermore, the filling phase is a silane-modified carboxylated nanocellulose aerogel; Furthermore, the unit cell period size of the three-period minimal surface is 1~5 mm, the skeleton porosity is 50%~80%, and the channel connectivity is ≥95%. Preferably, the skeleton porosity is 60%~80%.

[0009] In some embodiments of the present invention, the three-period minimal surface is selected from a Gyroid-type surface, a Diamond-type surface, a Primitive-type surface, or an I-WP-type surface; In some embodiments of the present invention, the ratio of the unit cell period size of the three-period minimal surface to the diameter of the nanocellulose aerogel is 1:(20~100); ensuring that the filling phase can perfectly fill all the pores of the main skeleton and retain the thermal insulation capability.

[0010] In some embodiments of the present invention, the main skeleton is made of a polymer material; preferably, the main skeleton is made of ABS resin.

[0011] In one embodiment of the present invention, the filling phase is carboxylated cellulose nanofibers modified with methyltrimethoxysilane (MTMS).

[0012] Furthermore, the carboxylated cellulose has a diameter of 10-50 nm and a carboxyl content of 0.8-1.2 mmol / g.

[0013] Furthermore, the porosity of the filling phase is 85%~90%, the thermal conductivity is 0.023~0.03W / (mK), and the compressive strength is 0.5~0.8MPa.

[0014] Furthermore, the main skeleton and the filling phase are bonded together through silicon-oxygen bonds and hydrogen bonds, with an interfacial shear strength ≥0.6 MPa.

[0015] In some preferred embodiments, the composite thermal insulation material has a gradient structure along the heat flow direction.

[0016] Preferably, in the composite thermal insulation material, the porosity of the main skeleton decreases continuously from 80% in the surface layer to 50% in the core layer. Based on this scheme, the filling amount of the thermal insulation material varies from the surface layer to the core layer, and the density of the filling phase varies from 50 mg / cm³. 3 Continuous gradient increase to 150 mg / cm 3 .

[0017] The second objective of this invention is to provide a method for preparing the composite thermal insulation material, the method comprising adding an MTMS solution of a certain pH value dropwise to a CNF-C solution, mixing it, filling it into a TPMS framework that has been surface-hydroxylated, and then freeze-drying it after the reaction to obtain the composite thermal insulation material.

[0018] Furthermore, the preparation method includes steps S1, S2, and S3; S1. Preparation of carboxylated cellulose nanofiber dispersion: Take a carboxylated cellulose nanofiber solution (CNF-C), and ultrasonically treat it to form a uniform dispersion; S2. Silane modification: Prepare a methyltrimethoxysilane hydrolysate, adjust the pH to 4±0.5, add the carboxylated cellulose nanofiber dispersion obtained in step S1 dropwise, and stir the reaction to obtain a hybrid sol; S3. Filling and curing: Provide a surface-hydroxylated TPMS skeleton, immerse it in the hybrid sol obtained in step S2, and freeze-dry it to obtain the composite thermal insulation material.

[0019] In some embodiments, in step S1, the mass fraction of carboxylated cellulose nanofibers in the dispersion is 1-10 wt%; in step S1, the treatment conditions are ultrasonic treatment at 300-500 W for 30-90 min. Ultrasonic treatment exposes more CNF-C surface active sites and reduces solution viscosity, providing a uniform matrix for subsequent MTMS modification.

[0020] In some embodiments, the MTMS solution is prepared by mixing MTMS and water in equal proportions, adjusting the pH with hydrochloric acid, and stirring at 400-600 r / min for 5-15 min.

[0021] In some implementations, the TPMS skeleton in step S3 is selected from Gyroid-type surfaces, Diamond-type surfaces, Primitive-type surfaces, or I-WP-type surfaces.

[0022] In some embodiments, in step S1 and step S2, hydrochloric acid is used to adjust the pH to 4 ± 0.5; preferably, pH = 4 ± 0.2. In some implementations, in step S2, the mass ratio of MTMS to CNF-C is controlled to be 1:(10~20). In some embodiments, the stirring conditions in step S2 are: stirring at 400~600 r / min for 30~90 min.

[0023] In some embodiments, in step S3, the TPMS framework is made of a polymer material that has undergone surface hydroxylation treatment. In one embodiment of the present invention, the surface hydroxylation treatment method is to treat with 5% NaOH solution at 60°C for 20 min.

[0024] A third objective of this invention is to provide applications of the composite thermal insulation material in at least one of the following fields: spacecraft thermal protection systems, vacuum insulation panels, building insulation materials, power battery module insulation, military protective equipment, precision instrument insulation, greenhouse insulation, and vaccine insulation.

[0025] Beneficial effects (1) The present invention provides a composite thermal insulation material and its preparation method. The material has excellent comprehensive performance, and also has excellent thermal insulation performance, mechanical properties and water resistance. (2) The present invention also provides a method for preparing the composite thermal insulation material. The method is simple and environmentally friendly, and the structure can be easily controlled. By adjusting the key parameters such as the number of cycles, porosity and aerogel filling amount of TPMS, the thermal conductivity and compressive strength of the composite thermal insulation material can be precisely designed to meet the specific needs of different application scenarios. (3) The thermal conductivity of the composite thermal insulation material of the present invention is as low as 0.020 W / (mK), reaching the ultra-low thermal conductivity level; the thermal insulation performance is significantly lower than that of pure CNF aerogel, simple TPMS skeleton, and commercial thermal insulation material - polystyrene foam, mainly due to the effective suppression of gas convection heat transfer in nanopores by MTMS modification. (4) The composite thermal insulation material of the present invention has good mechanical properties, with a compressive strength of 1.0~1.5MPa, which is 100%~200% higher than that of pure aerogel; at the same time, the material has good elasticity, which can effectively withstand the load in practical applications and provide reliable structural support. (5) The composite thermal insulation material of the present invention has enhanced water resistance: the water contact angle can reach more than 100°, exhibiting good hydrophobicity. The overall water resistance performance is better than EPS and significantly higher than that of simple aerogel (60°), which solves the problem of easy water absorption inherent in nanocellulose aerogel and ensures its stable thermal insulation performance in humid or outdoor environments. Attached Figure Description

[0026] Figure 1 The Gyroid-type TPMS skeleton structure used in the embodiments (a) and the composite thermal insulation material prepared in Example 1 (b). Figure 2 Electron micrograph of the aerogel obtained in Example 1; Figure 3 Electron micrograph of the aerogel obtained in Example 2; Figure 4 Electron micrograph of the aerogel obtained in Example 3. Detailed Implementation

[0027] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention are described in detail below with reference to the examples. The examples are implemented based on the technical solution of the present invention, and detailed implementation methods and processes are given. However, the scope of protection of the present invention is not limited to the following examples. Experimental methods in the following examples that do not specify specific conditions are generally performed under conventional conditions or according to the conditions recommended by the manufacturer.

[0028] In an embodiment of the present invention, the TPMS skeleton used is made of ABS-like resin.

[0029] In the embodiments of the present invention, the TPMS skeleton is 3D printed and is of type Gyroid; Diamond type curved surface, Primitive type curved surface or I-WP type curved surface skeleton can achieve similar technical effects.

[0030] The detection methods involved in the embodiments are all common testing methods in the field, including thermal conductivity, compressive strength, water contact angle, deformation recovery rate, etc.

[0031] Example 1: Preparation of Composite Thermal Insulation Material S1. TPMS skeleton preparation: TPMS skeleton (Gyroid type, 2mm single cell period, 20mm×20mm×20mm size, 70% porosity) was printed using a DLP 3D printer, treated with 5% NaOH solution at 60℃ for 20min, washed with deionized water until neutral, and dried at 60℃ for later use.

[0032] S2. Preparation of CNF-C dispersion: Take 50 mL of 1 wt% carboxylated cellulose nanofiber solution and sonicate at 300 W for 30 min to form a uniform dispersion.

[0033] S3. Preparation of MTMS hydrolysate: Mix 1 mL of MTMS with 1 mL of deionized water, add 0.1 mol / L hydrochloric acid to adjust the pH to 4, and stir at 500 r / min for 10 min.

[0034] S4. Preparation of hybrid sol: 1 mL of MTMS hydrolysate from S3 was added dropwise to CNF-C dispersion from S2, and the mass ratio of MTMS to CNF-C was controlled at 1:1. The mixture was stirred at 300 r / min for 1 h to form a homogeneous sol.

[0035] S5. Filling and curing: The TPMS skeleton prepared in step S1 is fixed in a polytetrafluoroethylene mold, and the hybrid sol of S4 is injected under vacuum (-0.09MPa). It is then frozen at -40℃ for 12h, followed by freeze drying (-55℃, ≤10Pa) for 24h to obtain the composite thermal insulation material.

[0036] Example 2 Preparation of composite thermal insulation material S1. TPMS skeleton preparation: TPMS skeleton (Gyroid type, 2mm single cell period, 20mm×20mm×20mm size, 70% porosity) was printed using a DLP 3D printer, treated with 5% NaOH solution at 60℃ for 20min, washed with deionized water until neutral, and dried at 60℃ for later use.

[0037] S2. Preparation of CNF-C dispersion: Take 50 mL of 1 wt% carboxylated cellulose nanofiber solution and sonicate at 300 W for 30 min to form a uniform dispersion.

[0038] S3. Preparation of MTMS hydrolysate: Measure 1 mL of MTMS and mix with 1 mL of deionized water, add 0.1 mol / L hydrochloric acid to adjust the pH to 4, and stir at 500 r / min for 10 min.

[0039] S4. Preparation of hybrid sol: 1 mL of MTMS hydrolysate from S3 was added dropwise to CNF-C dispersion from S2, and the mass ratio of MTMS to CNF-C was controlled at 1:2. The mixture was stirred at 300 r / min for 1 h to form a homogeneous sol.

[0040] S5. Filling and curing: The TPMS skeleton of S1 is fixed in a polytetrafluoroethylene mold, and the hybrid sol of S4 is injected under vacuum (-0.09MPa). It is then frozen at -40℃ for 12h, followed by freeze drying (-55℃, ≤10Pa) for 24h to obtain the composite thermal insulation material.

[0041] Example 3 Preparation of composite thermal insulation material S1. TPMS skeleton preparation: TPMS skeleton (Gyroid type, 2mm single cell period, 20mm×20mm×20mm size, 70% porosity) was printed using a DLP 3D printer, treated with 5% NaOH solution at 60℃ for 20min, washed with deionized water until neutral, and dried at 60℃ for later use.

[0042] S2. Preparation of CNF-C dispersion: Take 50 mL of 1 wt% carboxylated cellulose nanofiber solution and sonicate at 300 W for 30 min to form a uniform dispersion.

[0043] S3. Preparation of MTMS hydrolysate: Measure 1 mL of MTMS and mix with 1 mL of deionized water, add 0.1 mol / L hydrochloric acid to adjust the pH to 4, and stir at 500 r / min for 10 min.

[0044] S4. Preparation of hybrid sol: 1 mL of MTMS hydrolysate from S3 was added dropwise to CNF-C dispersion from S2, and the mass ratio of MTMS to CNF-C was controlled at 1:3. The mixture was stirred at 300 r / min for 1 h to form a homogeneous sol.

[0045] S5. Filling and curing: The TPMS skeleton of S1 is fixed in a polytetrafluoroethylene mold, and the hybrid sol of S4 is injected under vacuum (-0.09MPa). It is then frozen at -40℃ for 12h, followed by freeze drying (-55℃, ≤10Pa) for 24h to obtain the composite thermal insulation material.

[0046] Example 4 Composite thermal insulation material S1. TPMS skeleton preparation: TPMS skeleton (Gyroid type, 2mm single cell period, 20mm×20mm×20mm size, 60% porosity) was printed using a DLP 3D printer, treated with 5% NaOH solution at 60℃ for 20min, washed with deionized water until neutral, and dried at 60℃ for later use.

[0047] S2. Preparation of CNF-C dispersion: Take 50 mL of 1 wt% carboxylated cellulose nanofiber solution and sonicate at 300 W for 30 min to form a uniform dispersion.

[0048] S3. Preparation of MTMS hydrolysate: Measure 1 mL of MTMS and mix with 1 mL of deionized water, add 0.1 mol / L hydrochloric acid to adjust the pH to 4, and stir at 500 r / min for 10 min.

[0049] S4. Preparation of hybrid sol: 1 mL of MTMS hydrolysate from S3 was added dropwise to CNF-C dispersion from S2, and the mass ratio of MTMS to CNF-C was controlled at 1:2. The mixture was stirred at 300 r / min for 1 h to form a homogeneous sol.

[0050] S5. Filling and curing: The TPMS skeleton of S1 is fixed in a polytetrafluoroethylene mold, and the hybrid sol of S4 is injected under vacuum (-0.09MPa). It is then frozen at -40℃ for 12h, followed by freeze drying (-55℃, ≤10Pa) for 24h to obtain the composite thermal insulation material.

[0051] Example 5 Composite Thermal Insulation Material S1. TPMS skeleton preparation: TPMS skeleton (Gyroid type, 3mm single cell period, 20mm×20mm×20mm size, 80% porosity) was printed using a DLP 3D printer, treated with 5% NaOH solution at 60℃ for 20min, washed with deionized water until neutral, and dried at 60℃ for later use.

[0052] S2. Preparation of CNF-C dispersion: Take 50 mL of 1 wt% carboxylated cellulose nanofiber solution and sonicate at 300 W for 30 min to form a uniform dispersion.

[0053] S3. Preparation of MTMS hydrolysate: Measure 1 mL of MTMS and mix with 1 mL of deionized water, add 0.1 mol / L hydrochloric acid to adjust the pH to 4, and stir at 500 r / min for 10 min.

[0054] S4. Preparation of hybrid sol: 1 mL of MTMS hydrolysate from S3 was added dropwise to CNF-C dispersion from S2, and the mass ratio of MTMS to CNF-C was controlled at 1:2. The mixture was stirred at 300 r / min for 1 h to form a homogeneous sol.

[0055] S5. Filling and curing: The TPMS skeleton of S1 is fixed in a polytetrafluoroethylene mold, and the hybrid sol of S4 is injected under vacuum (-0.09MPa). It is then frozen at -40℃ for 12h, followed by freeze drying (-55℃, ≤10Pa) for 24h to obtain the composite thermal insulation material.

[0056] The composite thermal insulation materials prepared in Examples 1-5 of this invention can all achieve a deformation recovery of 80% or more.

[0057] Comparative Example 1: TPMS framework preparation A Gyroid-type TPMS skeleton (2mm cell period, 20mm×20mm×20mm size, 70% porosity) was prepared using the same 3D printing parameters as in Example 1. The surface treatment steps were the same as in Example 1, except that no filling treatment was performed, and it was directly used for performance testing.

[0058] Comparative Example 2: Preparation of Simple Nanocellulose Aerogel 1. Dispersion preparation: Take the purified nanocellulose (CNF-C) dispersion (1wt%), add 0.5% crosslinking agent (glutaraldehyde) and catalyst (0.1 mol / L hydrochloric acid, adjust pH to 4), and ultrasonically disperse at 300W for 30 min until uniform.

[0059] 2. Molding and gelation: The TPMS skeleton was placed in the mold, and the nanocellulose dispersion was injected into the skeleton pores under vacuum (-0.08 MPa) (using capillary effect to achieve uniform filling). The mixture was left to stand at room temperature for 12 hours to form a wet gel.

[0060] 3. Freeze-drying molding: The TPMS skeleton containing moist gel is placed in a freeze dryer, pre-frozen at -50℃, with a vacuum degree of <10 Pa, and dried for 24 hours to remove moisture and form a nanocellulose aerogel-TPMS composite.

[0061] Comparative Example 3: Commercially available EPS foam materials Commercially available EPS foam material was selected and cut into 20mm×20mm×20mm samples for comparative testing.

[0062] Comparative Example 4 The pH of the MTMS hydrolysate preparation step was controlled at 2 and 6, respectively, while other steps were the same as in Example 1. Under these conditions, effective aerogel materials could not be obtained.

[0063] like Figure 1 (a) shows the Gyroid-type TPMS skeleton used in the embodiments of the present invention; the composite thermal insulation material prepared in Example 1 is as follows: Figure 1 As shown in (b).

[0064] like Figure 2-4 The images shown are electron microscope images of the aerogels prepared in Examples 1-3 of the present invention: they exhibit a highly interconnected three-dimensional porous network with a multi-level pore structure, which can effectively suppress air convection and heat conduction; and the skeleton is continuous and has a uniform thickness.

[0065] Table 1 Performance Test Results As shown in Table 1, the composite thermal insulation material of this invention exhibits significant advantages in thermal insulation performance, mechanical properties, and water contact angle. Regarding thermal insulation performance, the thermal conductivity of the composite thermal insulation materials in Examples 1-5 is in the range of 0.02-0.03 W / (mK), reaching an ultra-low thermal conductivity level. This is mainly due to the effective suppression of gas convection heat transfer within the nanopores by MTMS modification, fully demonstrating the significant thermal insulation performance of the composite thermal insulation material of this invention. It is lower than that of simple aerogel (0.033 W / (mK)), and far lower than that of simple TPMS (0.08 W / (mK)) and EPS (0.042 W / (mK)), showing a clear advantage in thermal insulation performance. In terms of mechanical properties, the compressive strength of the examples is between 1.2 and 1.49 MPa, which is tens of times that of simple aerogel (0.08 MPa) and far higher than that of EPS (0.3 MPa), meeting the structural support requirements in practical applications. Examples 2-4, in particular, show significant advantages in mechanical properties, with superior resistance to deformation and structural stability. In terms of water resistance, the water contact angle of the composite material of the present invention is greater than 90°, which is comparable to or better than EPS, and significantly higher than that of simple aerogel (60°), thus solving the problem of easy water absorption of nanocellulose aerogel.

[0066] In summary, the technical solution of this invention achieves a synergistic improvement in thermal insulation performance, mechanical properties, and water resistance through technical optimization, solving the problem that traditional thermal insulation materials cannot simultaneously achieve all the desired properties. It is more technically competitive in various scenarios such as aerospace equipment, building insulation materials, precision instrument insulation, and vaccine insulation.

[0067] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the present invention.

Claims

1. A composite thermal insulation material, characterized in that, The composite thermal insulation material is composed of a main framework and a filling phase, wherein the main framework is a tri-periodic minimal surface; and the filling phase is a silane-modified carboxylated nanocellulose aerogel. The cell period size of the tri-periodic minimal surface is 1-5 mm, and the skeleton porosity is 50%-80%, preferably 60%-80%.

2. The composite thermal insulation material according to claim 1, wherein the tri-periodic minimal surface is selected from a Gyroid-type surface, a Diamond-type surface, a Primitive-type surface or an I-WP-type surface; and / or, the ratio of the cell period size of the tri-periodic minimal surface to the diameter of the nanocellulose aerogel is 1: (20-100).

3. The composite thermal insulation material according to claim 1, wherein the filling phase is a carboxylated cellulose nanofiber modified by methyltrimethoxysilane; and / or, the channel connectivity of the tri-periodic minimal surface is greater than or equal to 95%. The diameter of the carboxylated cellulose is 10-50 nm, and the carboxyl content is 0.8-1.2 mmol / g. The porosity of the filling phase is 85%-90%, the thermal conductivity coefficient is 0.023-0.03 W / (m.K), and the compressive strength is 0.5-0.8 MPa. The preparation method comprises the following steps: S1. Preparation of a carboxylated cellulose nanofiber dispersion liquid: taking a carboxylated cellulose nanofiber solution, and forming a uniform dispersion liquid after ultrasonic treatment; 4. The composite thermal insulation material of claim 1, wherein S2. Silane modification: preparing a methyltrimethoxysilane hydrolysis solution, adjusting the pH to 4±0.5, adding the carboxylated cellulose nanofiber dispersion liquid prepared in step S1 dropwise, and preparing a hybrid sol after stirring and reaction; 5. The composite thermal insulation material of claim 1, wherein S3. Filling and solidification: providing a TPMS framework, immersing the hybrid sol prepared in step S2 into the framework, and filling the hybrid sol into the framework under a certain vacuum degree, and then freeze-drying to obtain the composite thermal insulation material.

6. Process for the production of the composite thermal insulation material according to any one of claims 1 to 5, characterized in that, 7. The preparation method of the composite thermal insulation material according to claim 6, wherein in step S1, the mass fraction of the carboxylated cellulose nanofiber in the dispersion liquid is 1-10 wt%; and / or, the treatment condition is 300-500 W ultrasonic treatment for 30-90 min.

8. The preparation method of the composite thermal insulation material according to claim 6, wherein in step S2, hydrochloric acid is used to adjust the pH; and / or, in step S2, the mass ratio of MTMS to CNF-C is controlled to be 1: (10-20); and / or, the stirring condition in step S2 is 400-600 r / min stirring for 30-90 min.

9. The preparation method of the composite thermal insulation material according to claim 6, wherein in step S3, the material of the TPMS framework is a high polymer material, which is subjected to surface hydroxylation treatment. The composite thermal insulation material is applied in at least one of the following fields: a spacecraft thermal protection system, a vacuum thermal insulation panel, a building thermal insulation material, a power battery module thermal insulation, a military protective equipment, a precision instrument thermal insulation, a greenhouse thermal insulation, and a vaccine thermal insulation. ​ ​ ​ ​ ​ ​ ​ ​ ​ 10. Use of the composite thermal insulation material according to any one of claims 1 to 5, or of the composite thermal insulation material produced according to any one of claims 6 to 9, characterized in that ​

Images