Green leaf-imitated porous hydrogel as well as preparation method and application thereof

Abstract

The invention discloses green leaf-imitated porous hydrogel as well as a preparation method and application thereof, and belongs to the technical field of hydrogel materials. The preparation method of the green leaf-imitated porous hydrogel comprises the following steps: mixing polyvinyl alcohol, tannic acid and a composite pigment in a solid state, and grinding to form uniformly dispersed mixed powder; then spraying a glutaraldehyde solution to the mixed powder, carrying out a cross-linking reaction at room temperature, and washing after the reaction to obtain hydrogel; soaking the hydrogel in a lithium chloride solution, and taking out the hydrogel after soaking to obtain the green leaf-imitated hydrogel with the automatic moisture absorption function; the hydrogel has a porous structure, can automatically absorb moisture and simulate a vegetation spectrum in a 400-2500nm wave band at high precision, is suitable for covering the surface of fabric or equipment so as to simulate the spectrum and thermal characteristics of vegetation, and can be widely applied to the field of infrared camouflage.

Description

Technical Field

[0001] This invention relates to a porous hydrogel that mimics green leaves, its preparation method, and its application, belonging to the field of hydrogel materials technology. Background Technology

[0002] As reconnaissance technology enters the multi-spectral and intelligent era, traditional camouflage materials face severe challenges in countering advanced detection methods such as hyperspectral and infrared sensors. Existing materials mostly focus on static color simulation, exhibiting significant shortcomings in multi-spectral compatibility and dynamic environmental adaptability. Therefore, developing a new generation of camouflage materials capable of accurately simulating vegetation characteristics across a wide spectral range and possessing autonomous thermal management capabilities has become an urgent need to enhance battlefield survivability.

[0003] Ideal camouflage materials need to accurately simulate the spectral reflectance characteristics and thermal management properties of natural vegetation in the visible to near-infrared (400-2500nm) band to effectively evade electro-optical reconnaissance. Existing camouflage materials, such as camouflage paint and synthetic fiber camouflage nets, have the following shortcomings: First, they are difficult to achieve a spectral reflectance curve that is highly consistent with real green leaves, making them easy to expose targets in the near-infrared band; second, they lack the autonomous humidity regulation ability to simulate the hygroscopic-transpiration cycle of plant leaves, resulting in insufficient thermal stability and environmental adaptability. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a biomimetic porous hydrogel, its preparation method, and its applications. This hydrogel integrates a biomimetic porous structure, autonomous moisture absorption and transpiration functions, the ability to accurately simulate vegetation spectra in the 400-2500nm wavelength range, and excellent mechanical properties, significantly improving the camouflage reliability and durability of the material in complex environments.

[0005] To achieve the above objectives, the following technical solution is provided: The first objective of this invention is to provide a method for preparing a porous hydrogel that mimics green leaves, the method comprising the following steps: (1) Raw material mixing: Polyvinyl alcohol, tannic acid and composite pigment are mixed in a solid state and ground to form a uniformly dispersed mixed powder; (2) Crosslinking treatment: Spray glutaraldehyde solution onto the mixed powder obtained in step (1), perform crosslinking reaction at room temperature, wash after reaction to obtain hydrogel; (3) Moisture-absorbing functionalization: The hydrogel obtained in step (2) is immersed in lithium chloride solution. After immersion, it is taken out to obtain a green leaf-like hydrogel with autonomous moisture-absorbing function.

[0006] In one embodiment, the degree of polymerization of the polyvinyl alcohol in step (1) is 2100~2500.

[0007] In one embodiment, in step (1), the mass ratio of polyvinyl alcohol to tannic acid is 10:9, and the amount of composite pigment accounts for 1 to 3% of the total mass of the mixed powder.

[0008] In one embodiment, the composite pigment in step (1) is an organo-modified montmorillonite with reactive dye intercalation, wherein the reactive dyes are CI Reactive Yellow 145 and CI Reactive Blue 21, and the organo-modified montmorillonite is sodium-based montmorillonite modified by the organomodifier hexadecyltrimethylammonium bromide.

[0009] In one embodiment, the organo-modified montmorillonite is a silicate material with a layered structure. After modification with a cationic surfactant, its interlayer domains change from hydrophilic to hydrophobic, enabling it to effectively load and fix reactive dye molecules through hydrophobic interactions and van der Waals forces. This structure not only improves the thermal and light stability of the dye, but also enables it to exhibit optical properties similar to natural chlorophyll in the 400-2500 nm wavelength range, thereby achieving high-precision spectral simulation.

[0010] In one embodiment, the total mass ratio of organo-modified montmorillonite to reactive dye in the composite pigment is 1:1, and the mass ratio of Reactive Yellow 145 to Reactive Blue 21 is 2:1.

[0011] In one embodiment, the specific preparation process of the composite dye is as follows: Step 1: Organic modification of montmorillonite 1) Suspension preparation: Sodium-based montmorillonite is added to water and a stable montmorillonite suspension is formed under constant temperature magnetic stirring; 2) Preparation of modifier solution: Weigh CTAB and dissolve it in water to form a CTAB aqueous solution; 3) Ion exchange reaction: Under continuous stirring, CTAB aqueous solution is added dropwise to montmorillonite suspension to carry out ion exchange reaction; 4) Washing and drying: After the reaction is complete, centrifuge the mixed suspension, discard the supernatant, wash, and dry; 5) Grinding: Grind the dried product and pass it through a 200-mesh sieve to obtain organo-modified montmorillonite (OMMT) powder; Step 2: Intercalation of reactive dyes with organomontmorillonite 1) Preparation of dye mother liquor: Accurately weigh CI Reactive Yellow 145 and CI Reactive Blue 21, maintaining a mass ratio of 2:1; dissolve them in water to prepare a mixed dye aqueous solution with a total concentration of 5 g / L; 2) Intercalation and composite reaction: The organo-modified montmorillonite (OMMT) obtained in step 1 is added to the mixed dye solution, and the pH value of the system is adjusted to 6-7; it is placed in a water bath at 50~60℃ and stirred under light-protected conditions. After the reaction is completed, it is centrifuged, the precipitate is collected, washed, and dried to obtain the reactive dye intercalated organo-modified montmorillonite, i.e., composite dye.

[0012] In one embodiment, in step 1, 1) the constant temperature magnetic stirring speed is 500~800 rpm, and the time is 5~10h.

[0013] In one embodiment, in step 1, 1) the concentration of the montmorillonite suspension is 1~5g / 100mL.

[0014] In one embodiment, in step 1, 2) the concentration of the CTAB aqueous solution is 3~4g / 100mL.

[0015] In one embodiment, in step 1, 3) the ion exchange reaction temperature is 50~60℃ and the time is 8~16h.

[0016] In one embodiment, in step 2, 2) the total mass ratio of organo-modified montmorillonite to reactive dye is 1:1.

[0017] In one embodiment, in step 2, 3) the stirring reaction temperature is 50~60℃, the speed is 300~600rpm, and the time is 24~36h.

[0018] In one embodiment, the concentration of the glutaraldehyde solution in step (2) is 2-4 wt%, and the spraying amount is such that the composite powder is uniformly wetted.

[0019] In one embodiment, the room temperature crosslinking reaction time in step (2) is 15 to 30 hours, preferably 18 hours.

[0020] In one embodiment, the washing in step (2) specifically involves rinsing with deionized water until the residual glutaraldehyde is completely removed.

[0021] In one embodiment, the concentration of the lithium chloride solution in step (3) is 10-20 wt%, and the soaking time is 5-20 hours; more preferably, the concentration of the lithium chloride solution in step (3) is 10 wt%, and the soaking time is 14 hours.

[0022] The second objective of this invention is to provide a green leaf-like hydrogel with autonomous moisture absorption function prepared by the method described above.

[0023] In one embodiment, the hydrogel has a porous network structure and good self-hygroscopic ability, and its reflectance spectrum in the 400-2500 nm band is ≥94% similar to that of natural leaves.

[0024] A third objective of this invention is to provide the application of the aforementioned self-moisturizing biomimetic hydrogel in the field of infrared camouflage, suitable for covering fabric or equipment surfaces to simulate the spectral and thermal properties of vegetation.

[0025] Beneficial effects: This invention is the first to combine biomimetic structural design, autonomous moisture absorption function and high-precision spectral simulation, overcoming the shortcomings of traditional camouflage materials in terms of environmental adaptability and spectral stability. (1) Compared with the traditional solution method, the powder solid-liquid reaction method of the present invention has significant advantages: powder mixing effectively avoids component agglomeration and sedimentation, and the interparticle gaps are fixed in situ into a continuous three-dimensional macroporous network, providing channels for rapid water adsorption and transport, which is the key to achieving high water absorption rate and rapid moisture absorption; ball milling process further refines the particles, making the network more uniform and stable, and has the effects of improving mechanical strength, simplifying post-processing, and being environmentally friendly. (2) This invention constructs a polyvinyl alcohol-tannic acid porous cross-linked network and combines it with lithium chloride hygroscopic functional treatment to achieve continuous autonomous hygroscopic capacity and high-precision spectral simulation function. Through the synergistic effect of porous structure and lithium chloride functional treatment, it simulates the hygroscopic-transpiration cycle behavior of plant leaves and achieves autonomous humidity regulation and thermal management. (3) The green leaf-like hydrogel prepared by the present invention is highly consistent with the spectrum of real leaves in the visible light-near infrared band, with a similarity of ≥94%. Attached Figure Description

[0026] Figure 1 A comparison of the spectral reflectance curves of the leaf-inspired hydrogel prepared in Example 1 and real leaves; Figure 2 The pore size distribution curve of the green leaf-inspired hydrogel prepared in Example 1 is shown. Figure 3 A scanning electron microscope (SEM) cross-sectional image of the green leaf-inspired hydrogel prepared in Example 1; Figure 4 A scanning electron microscope (SEM) cross-sectional image of the green leaf-like hydrogel prepared for Comparative Example 1 (pure water spraying); Figure 5 SEM cross-sectional image of the green leaf-inspired hydrogel prepared for Comparative Example 2 (common reactive dye); Figure 6 The image shows the cyclic moisture absorption of the green leaf-like hydrogel prepared in Example 1. Detailed Implementation

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. The specific embodiments described below further illustrate the present invention.

[0028] The testing method involved in this invention: 1. Tensile strength: Clamping length 20mm, speed 500mm / min, tensile testing machine is used to perform the breakage test, and the tensile strength on the ordinate is read.

[0029] 2. Tensile strength: Clamping length 20mm, speed 500mm / min, tensile testing machine is used to perform tensile test, and the tensile strength on the horizontal axis is read.

[0030] 3. Maximum water absorption rate: After the hydrogel is completely dried, weigh it (m1), immerse it in water until it no longer absorbs water, and weigh it (m2). Maximum water absorption rate = .

[0031] 4. Spectral similarity: The visible-near-infrared spectra of the hydrogel were measured using a UV-Vis-NIR spectrophotometer (Lambda950), and the correlation coefficient was calculated in Origin with the mean of the standard plant spectral curves.

[0032] The raw materials involved in this invention are: The preparation of composite pigments includes the following: 1. Raw materials and reagents Montmorillonite (MMT): Sodium-based montmorillonite, purity ≥98%, cation exchange capacity (CEC) of 0.8-1.2 mmol / g; Reactive dyes: CI Reactive Yellow 145, CI Reactive Blue 21; Modifier: hexadecyltrimethylammonium bromide (CTAB), analytical grade; Solvent: Deionized water; pH adjusters: hydrochloric acid (HCl) solution (1 mol / L), sodium hydroxide (NaOH) solution (1 mol / L).

[0033] 2. Preparation steps Step 1: Organic modification of montmorillonite (1) Preparation of suspension: Weigh 5.0 g of sodium montmorillonite and slowly add it to 500 mL of deionized water at 60℃. Stir at 500 rpm for 6 hours under constant temperature magnetic stirring to form a stable suspension. (2) Preparation of modifier solution: Weigh 3.28g of CTAB and dissolve it in 100 mL of deionized water at 60℃ to obtain CTAB aqueous solution; (3) Ion exchange reaction: Under continuous stirring, CTAB aqueous solution was added dropwise to montmorillonite suspension. After the addition was completed, the reaction system was kept at 60 °C and stirred continuously for 12 hours to ensure that the cation exchange reaction was fully carried out. (4) Washing and drying: After the reaction is completed, the mixed suspension is centrifuged (8000 rpm, 10 min), the supernatant is discarded, and the precipitate is repeatedly washed with hot deionized water at 60 °C until no silver bromide white precipitate is formed in the supernatant when tested with 0.1 mol / L AgNO3 solution. The obtained precipitate is placed in a vacuum drying oven at 80 °C and dried for 12 hours. (5) Grinding: Grind the dried product and pass it through a 200-mesh sieve to obtain organo-modified montmorillonite (OMMT) powder, and store it in a sealed container for later use; Step 2: Intercalation of reactive dyes with organomontmorillonite (1) Preparation of dye mother liquor: Accurately weigh CI Reactive Yellow 145 and CI Reactive Blue 21, keeping their mass ratio at 2:1; dissolve both in deionized water to prepare a mixed dye aqueous solution with a total concentration of 5 g / L, and sonicate for 10 minutes to ensure complete dissolution; (2) Intercalation and composite reaction: Weigh 1g of organo-modified montmorillonite (OMMT) and add it to 200 mL of the above mixed dye solution (the total mass ratio of organo-modified montmorillonite to reactive dye is 1:1). Adjust the pH of the system to 6-7 with dilute HCl and NaOH solutions. (3) Constant temperature stirring: Place the reaction system in a 60℃ water bath and stir magnetically at 400 rpm for 24 hours under light-protected conditions to ensure that the dye molecules diffuse fully and intercalate into the interlayer domain of montmorillonite. After the reaction is completed, centrifuge the suspension (8000 rpm, 10 min), collect the precipitate, and wash the precipitate 2-3 times with anhydrous ethanol. (4) Drying and finished product: The final green solid is placed in a vacuum drying oven at 60℃ and dried for 12 hours. After being taken out, it is ground to obtain the active dye intercalated montmorillonite green pigment, i.e., composite dye.

[0034] Example 1 A method for preparing a porous hydrogel that mimics green leaves includes the following: (1) Raw material mixing: Weigh 1g of polyvinyl alcohol, 0.9g of tannic acid and 0.0285g of composite pigment and mix them. Then, form a uniform dispersion system by ball milling to obtain a mixed powder. (2) Crosslinking treatment: Spray the mixed powder with 10 mL of 3 wt% glutaraldehyde solution, and crosslink at room temperature for 18 hours to form a preliminary hydrogel. Then rinse with deionized water until the residual glutaraldehyde is completely removed. (3) Moisture-absorbing functionalization: The hydrogel treated in step (2) is immersed in a 10wt% lithium chloride solution for 14 hours. After taking it out, a green leaf-like hydrogel with self-moisture-absorbing function is obtained.

[0035] Example 2 A method for preparing a porous hydrogel that mimics green leaves includes the following: (1) Raw material mixing: Weigh 1g of polyvinyl alcohol, 0.9g of tannic acid and 0.038g of composite pigment and mix them. Then, ball mill them to form a uniform powder dispersion system to obtain mixed powder. (2) Crosslinking treatment: Spray the mixed powder with 10 mL of 3 wt% glutaraldehyde solution, and crosslink at room temperature for 18 hours to form a preliminary hydrogel. Then rinse with deionized water until the residual glutaraldehyde is completely removed. (3) Moisture-absorbing functionalization: The hydrogel treated in step (2) is immersed in a 10wt% lithium chloride solution for 14 hours. After taking it out, a green leaf-like hydrogel with self-moisture-absorbing function is obtained.

[0036] Example 3 A method for preparing a porous hydrogel that mimics green leaves includes the following: (1) Raw material mixing: Weigh 1g of polyvinyl alcohol, 0.9g of tannic acid and 0.0285g of composite pigment and mix them. Then, ball mill them to form a uniform powder dispersion system to obtain mixed powder. (2) Crosslinking treatment: Spray the mixed powder with 10 mL of 2 wt% glutaraldehyde solution, and crosslink at room temperature for 18 hours to form a preliminary hydrogel. Then rinse with deionized water until the residual glutaraldehyde is completely removed. (3) Moisture-absorbing functionalization: The hydrogel treated in step (2) is immersed in a 10wt% lithium chloride solution for 14 hours. After taking it out, a green leaf-like hydrogel with self-moisture-absorbing function is obtained.

[0037] Example 4 A method for preparing a porous hydrogel that mimics green leaves includes the following: (1) Raw material mixing: Weigh 1g of polyvinyl alcohol, 0.9g of tannic acid and 0.0285g of composite pigment and mix them. Then, ball mill them to form a uniform powder dispersion system to obtain mixed powder. (2) Crosslinking treatment: Spray the mixed powder with 10 mL of 3 wt% glutaraldehyde solution, and crosslink at room temperature for 18 hours to form a preliminary hydrogel. Then rinse with deionized water until the residual glutaraldehyde is completely removed. (3) Moisture-absorbing functionalization: The hydrogel treated in step (2) is immersed in a 15wt% lithium chloride solution for 14 hours. After taking it out, a green leaf-like hydrogel with self-moisture-absorbing function is obtained.

[0038] Example 5 A method for preparing a porous hydrogel that mimics green leaves includes the following: (1) Raw material mixing: Weigh 1g of polyvinyl alcohol, 0.9g of tannic acid and 0.0285g of composite pigment and mix them. Then, ball mill them to form a uniform powder dispersion system to obtain mixed powder. (2) Crosslinking treatment: Spray the mixed powder with 10 mL of 3 wt% glutaraldehyde solution, and crosslink at room temperature for 18 hours to form a preliminary hydrogel. Then rinse with deionized water until the residual glutaraldehyde is completely removed. (3) Moisture-absorbing functionalization: The hydrogel treated in step (2) is immersed in a 10wt% lithium chloride solution for 7 hours. After taking it out, a green leaf-like hydrogel with self-moisture-absorbing function is obtained.

[0039] Results Analysis 1 The performance of the green leaf-like hydrogels with self-absorbing moisture function prepared in Examples 1-5 was tested, and the results are shown in Table 1: Table 1 Performance Tests of the Green Leaf-Inspired Hydrogel

[0040] The results show that the leaf-like hydrogel of the present invention, while maintaining high mechanical properties, possesses excellent water absorption and spectral simulation properties; Figure 1 It can be seen that the reflectance of the leaf-inspired hydrogel of the present invention is comparable to that of a real leaf, with a spectral similarity of over 94%; the pore size distribution curve is as follows. Figure 2 As shown.

[0041] Comparative Example 1 Pure water spraying process: This comparative example uses pure water to spray the mixed powder. The specific steps are as follows: (1) Raw material mixing: Weigh 1g of polyvinyl alcohol, 0.9g of tannic acid and 0.0285g of composite pigment and mix them. Then, ball mill them to form a uniform powder dispersion system to obtain mixed powder. (2) Crosslinking treatment: Spray the mixed powder obtained in step (1) with 10 mL of pure water and crosslink at room temperature for 18 hours to form a preliminary hydrogel; (3) Moisture-absorbing functionalization: The hydrogel obtained by crosslinking in step (2) is immersed in a 10wt% lithium chloride solution for 14 hours. After being taken out, a green leaf-like hydrogel with autonomous moisture-absorbing function is obtained.

[0042] Comparative Example 2 Common reactive dye process: In this comparative example, CI Reactive Yellow 145 and CI Reactive Blue 21 were mixed in a mass ratio of 2:1 as color-modifying dyes to prepare hydrogels. The specific steps are as follows: (1) Raw material mixing: Weigh 1g of polyvinyl alcohol 2488 type, 0.9g of tannic acid, 0.019g of CI active yellow and 0.0095g of CI active blue and mix them to form a uniform powder dispersion system to obtain the mixture powder; (2) Crosslinking treatment: Spray the mixed powder obtained in step (1) with 10 mL of 3 wt% glutaraldehyde solution and crosslink at room temperature for 18 hours to form a preliminary hydrogel; (3) Moisture-absorbing functionalization: The hydrogel treated in step (2) is immersed in a 10wt% lithium chloride solution for 14 hours. After taking it out, a green leaf-like hydrogel with self-moisture-absorbing function is obtained.

[0043] Comparative Example 3 Calcium chloride moisture absorption process: This comparative example uses calcium chloride as a moisture absorption regulator. The specific steps are as follows: (1) Raw material mixing: Weigh 1g of polyvinyl alcohol, 0.9g of tannic acid and 0.0285g of composite pigment and mix them. Then, ball mill them to form a uniform powder dispersion system to obtain the mixture powder. (2) Crosslinking treatment: Spray the mixed powder with 3wt% glutaraldehyde solution until moist, and crosslink at room temperature for 18 hours to form a preliminary hydrogel. Then rinse with deionized water until the residual glutaraldehyde is completely removed. (3) Moisture-absorbing functionalization: The treated hydrogel was soaked in a 10wt% calcium chloride solution for 14 hours. After taking it out, a green leaf-like hydrogel with autonomous moisture-absorbing function was obtained.

[0044] Results Analysis 2 The performance of the green leaf-like hydrogels prepared in Example 1 and Comparative Examples 1-3 was tested, and the results are shown in Table 2: Table 2 Performance Tests of the Green Leaf-Inspired Hydrogel

[0045] As shown in the table, Comparative Example 1 indicates that without glutaraldehyde crosslinking, a stable three-dimensional network structure cannot be formed, resulting in extremely poor mechanical properties (tensile strength 85 kPa, elongation 150%). Comparative Example 2 shows that while achieving color control, the composite pigment does not destroy the original three-dimensional cross-linked structure. Using ordinary dyes to replace composite pigments will severely damage the network structure, resulting in a sharp deterioration in its mechanical properties (tensile strength 65 kPa, elongation 50%) and water absorption (63%), highlighting the indispensability of composite pigments in maintaining structural stability and spectral accuracy.

[0046] The hydrogels of Example 1 and Comparative Examples 1-2 were directly observed using a scanning electron microscope (SEM), such as... Figure 3 (Example 1) Figure 4 (Comparative Example 1) and Figure 5 (Comparative Example 2) shows that Example 1 exhibits a uniform porous structure with interconnected surfaces, which is the structural basis for its high water absorption rate. In contrast, Comparative Examples 1 and 2 show structural collapse or inhomogeneity, resulting in a significant decrease in mechanical strength and other properties.

[0047] The green-like hydrogel prepared in Example 1 also exhibits good self-hygroscopic ability, as shown in its hygroscopic transpiration cycle curve during drying-100% hygroscopic absorption as follows: Figure 6 As shown.

[0048] Comparative Example 3 verified the irreplaceable role of lithium chloride in achieving efficient moisture absorption. Although its mechanical properties were similar to those of Example 1, its moisture absorption rate (40%) was much lower than that of Example 1 (110%).

[0049] This invention successfully prepared a green leaf-like self-hygroscopic hydrogel with excellent comprehensive performance by combining four aspects: "constructing a macroporous structure with powder precursors", "ensuring mechanical strength through chemical cross-linking of glutaraldehyde", "achieving stable spectral simulation with composite pigments", and "functionalizing lithium chloride to impart high-efficiency hygroscopicity". This invention solves the shortcomings of traditional camouflage materials in terms of environmental adaptability and spectral stability.

[0050] The embodiments provided above are not intended to limit the scope of the invention, nor are the described steps intended to limit the order of execution. Any obvious modifications made to the invention by those skilled in the art based on existing common knowledge also fall within the scope of protection defined by the claims.

Claims

1. A method for preparing a porous hydrogel mimicking green leaves, characterized in that, The method includes the following steps: (1) Raw material mixing: Polyvinyl alcohol, tannic acid and composite pigment are mixed in a solid state and ground to form a uniformly dispersed mixed powder; (2) Crosslinking treatment: Spray glutaraldehyde solution onto the mixed powder obtained in step (1), perform crosslinking reaction at room temperature, wash after reaction to obtain hydrogel; (3) Moisture-absorbing functionalization: The hydrogel obtained in step (2) is immersed in lithium chloride solution. After immersion, it is taken out to obtain a green leaf-like hydrogel with autonomous moisture-absorbing function.

2. The method according to claim 1, characterized in that, In step (1), the mass ratio of polyvinyl alcohol to tannic acid is 10:9, and the amount of composite pigment accounts for 1 to 3% of the total mass of the mixed powder.

3. The method according to claim 1, characterized in that, The composite pigment in step (1) is an organo-modified montmorillonite with reactive dye intercalation, wherein the reactive dyes are CI Reactive Yellow 145 and CI Reactive Blue 21, and the organo-modified montmorillonite is sodium-based montmorillonite modified by the organomodifier hexadecyltrimethylammonium bromide.

4. The method according to claim 3, characterized in that, The mass ratio of CI Reactive Yellow 145 to CI Reactive Blue 21 in the composite pigment is 2:1, and the total mass ratio of the organo-modified montmorillonite to the reactive dye is 1:

1.

5. The method according to claim 1, characterized in that, The concentration of the glutaraldehyde solution in step (2) is 2~4wt%, and the spraying amount is to uniformly wet the composite powder.

6. The method according to claim 1, characterized in that, The time for the room temperature crosslinking reaction in step (2) is 15~30h.

7. The method according to claim 1, characterized in that, The lithium chloride solution in step (3) has a concentration of 10-20 wt% and a soaking time of 5-20 hours.

8. The green leaf-like hydrogel with autonomous moisture absorption function prepared by the method according to any one of claims 1 to 7.

9. The leaf-like hydrogel with self-absorbing moisture function as described in claim 8, characterized in that, The leaf-inspired hydrogel has a porous network structure and good self-hygroscopic ability. Its reflectance spectrum in the 400-2500 nm band is ≥94% similar to that of natural leaves.

10. The application of the green leaf-like hydrogel with self-absorbing moisture function as described in claim 8 or 9 in the field of infrared camouflage.

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