Bionic hydrogel evaporator with salt-resistant antifouling function and preparation method thereof

Abstract

The present application belongs to the field of seawater desalination, and particularly relates to a biomimetic hydrogel evaporator with salt-resistant and antifouling functions and a preparation method thereof. In view of the fact that salt crystallization and marine biofouling occur on the surface of the existing hydrogel evaporator during seawater evaporation, the present application homogenizes and compiles high-entropy alloy nanoparticles with hydrogel, the molecular weight of the hydrogel ranges from 10000 to 100000, the mass ratio of the hydrogel matrix to the high-entropy alloy nanoparticles is 100:(5-20), and the hydrogel is in-situ cross-linked and solidified in a biomimetic mold with a Nepenthes peristome micro-nano structure. The cross-linking density and pore size of the hydrogel are changed by regulating the number of freeze-thaw cycles and operation time, so as to obtain mechanical strength capable of resisting external force and rapid water transmission capacity, and finally obtain the biomimetic hydrogel evaporator with salt-resistant and antifouling functions.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of seawater desalination, and particularly relates to a biomimetic hydrogel evaporator with salt-resistant and antifouling functions and a preparation method thereof. BACKGROUND

[0002] About 97.3% of the water resources on earth is seawater. Traditional seawater desalination technologies such as reverse osmosis and distillation have problems such as high energy consumption and complex equipment, and cannot be used on a large scale. Moreover, these solutions have a high degree of centralization and cannot achieve seawater desalination in dispersed areas. Under this background, the photo-thermal interface evaporation technology has been widely concerned due to its zero carbon emission, low centralization requirement and efficient utilization of renewable energy. The photo-thermal interface evaporation technology realizes low-heat-loss rapid evaporation by constructing a photo-thermal conversion layer on the water-air interface through photo-thermal materials, and is regarded as a revolutionary solution for seawater desalination. Among them, the porous hydrogel-based photo-thermal interface evaporator with strong water activation ability and fast water transmission speed has become a research hotspot.

[0003] When the hydrogel evaporator is applied to seawater desalination, salt crystallization and marine biofouling on its surface during the seawater evaporation process become two key factors limiting its large-scale service. During the photo-thermal conversion process, the accumulation of salt on the evaporation interface will form salt crystals, covering the surface of the photo-thermal material and blocking light absorption and water vapor transmission. Moreover, with the appearance of salt crystals, the evaporator is difficult to balance efficient heat transfer and salt migration. At the same time, the fouling biological community (such as bacteria, seaweed, etc.) in seawater begins to adsorb and parasitize when the material contacts seawater. These fouling organisms form a biofilm through metabolic activity, causing pore blockage and material corrosion of the evaporator. Therefore, whether it is salt crystallization on the surface during seawater desalination or biofouling formed by marine organisms, it will eventually adhere to the evaporator, block the water transmission holes, reduce the evaporation rate, and cause the failure of the evaporator. In addition, the mechanical strength that can resist environmental external forces while maintaining its own structure from being damaged is also one of the key properties that the hydrogel evaporator needs to meet. Therefore, developing a high-strength hydrogel evaporator with high photo-thermal conversion efficiency, high seawater desalination rate, and anti-salt and antifouling functions is an effective method to overcome the limitations of large-scale application of water evaporators.

[0004] Photo-thermal conversion materials play a core role in the design and optimization of solar interface evaporators. They convert solar energy into local heat energy through photo-thermal conversion effect, realizing efficient solar-thermal energy conversion. The light absorption efficiency, thermal conductivity and chemical stability of such materials directly determine the energy conversion efficiency and long-term operation stability of the evaporator. From the perspective of marine antifouling engineering, compared with the traditional strategy of adding antibacterial agents to the system, giving the photo-thermal conversion layer inherent antibacterial function through material design is a more sustainable solution. However, traditional photo-thermal conversion materials (such as carbon-based and noble metal nanomaterials) lack inherent antibacterial properties, making it difficult to meet the demand for long-term stable operation in marine environments. SUMMARY

[0005] In view of the main technical problems existing at present, the present application provides a high-strength biomimetic hydrogel evaporator with salt-resistant and antifouling functions and a preparation method thereof, aiming to solve the core defects of the prior art. The technical scheme realizes rapid forming manufacturing by designing a biomimetic structure and optimizing a preparation process, and obtains a biomimetic structure hydrogel evaporator with wide-spectrum photothermal response characteristics, high-efficiency desalination efficiency and persistent antifouling performance, thereby effectively guaranteeing long-term stable operation of the evaporation device under harsh working conditions and breaking through the technical obstacles of industrialization and popularization of traditional photothermal evaporation devices.

[0006] The structure of the mouth of the pitcher plant is composed of a large number of inclined micro-pits with sharp cantilever structures arranged in an overlapping manner, which can realize one-way rapid transportation of liquid on the solid surface without energy input and form a layer of limited water film. Due to the water film generated by the micro-pits and the rapid water transportation capacity generated by the Laplace pressure difference, the two jointly act on the pitcher plant biomimetic surface to present super-hydrophilic effect and Marangoni effect, which provides a new idea for preventing microbial attachment and ion exchange. The flowing water film effectively interferes with the interaction between marine organisms and the surface, reducing microbial attachment. At the same time, thanks to the combined action of the hydrophilic hydrogel substrate and the biomimetic structure, the flowing water film can be dynamically updated during the evaporation process, which can supplement water to the local area with rising salt concentration in the evaporation process and balance the salt concentration to prevent local supersaturation of salt ions and crystallization. In addition, the water film has weak interaction with salt ions, and the dynamic water film barrier reduces the affinity of salt ions with the surface, so that the salt ions tend to dissolve in the water body, reducing the nucleation probability of salt crystal nucleus and reducing the salt deposition on the evaporation interface, which makes the realization of the antifouling and salt-resistant functions of the hydrogel evaporator possible.

[0007] Based on the synergistic effect of multiple metals and the designability of components, a new high-entropy alloy system provides the possibility for this idea through a multi-main-element equal-atomic-ratio solid solution construction strategy. A face-centered cubic solid solution formed by five or more transition metal elements can realize an average light absorption rate of more than 92% in a wide spectrum range of 300nm-2500nm by means of d-d band transition and local surface plasmon resonance effect. The introduction of antibacterial element Cu can realize the coupling of photothermal effect and antibacterial effect, which constructs a dynamic antibacterial interface through metal ion slow release and synergistic photothermal effect. If the pitcher plant biomimetic structure is combined with this, multiple resistance and prevention of marine fouling organisms can be realized, which breaks through the limitations of traditional single antifouling mechanism in complex marine environment, and may show unique advantages in the fields of seawater desalination, medical instrument surface sterilization and other fields requiring high dynamic response, high efficiency energy conversion and low microbial pollution.

[0008] To achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0009] The application provides a high-strength biomimetic hydrogel evaporator with salt-resistant and anti-fouling functions, a real Nepenthes peristome structure is observed and designed to construct a Nepenthes biomimetic mold; the hydrogel evaporator has a mechanical strength capable of completing the replication of the biomimetic structure by regulating the molecular weight of a hydrogel component; the evaporator is a hydrogel composite material constructed by a high-entropy alloy nanodispersion system, the high-entropy alloy nanoparticles and the hydrogel are homogenized and compounded, and a structure with a three-dimensional network distribution characteristic of a nanometer reinforcing phase is formed by in-situ cross-linking and solidification; the cross-linking density and the pore size of the hydrogel are changed by regulating the number of freeze-thaw cycles and the operation time, so that the mechanical strength capable of resisting external force and the rapid water transport capacity are obtained.

[0010] The high-strength biomimetic hydrogel evaporator with salt-resistant and anti-fouling functions has a Nepenthes peristome biomimetic structure on the surface of the evaporator, and is composed of a hydrogel matrix and high-entropy alloy nanoparticles.

[0011] The high-entropy alloy nanoparticles have a solid solution structure, are uniformly dispersed in the hydrogel matrix, are composed of Fe, Ni, Ti, Cr, Mn and Cu metal elements in a six-element equal-atomic-ratio configuration (the atomic percentage of each metal element in the high-entropy alloy is equal), and realize component synergistic effect through a multi-principal-element solid solution structure.

[0012] The hydrogel matrix has a continuous phase structure, and is composed of a high-molecular network skeleton formed by physical cross-linking and solidification of polyvinyl alcohol (PVA).

[0013] In the application of seawater desalination, the hydrogel evaporator has the ability to resist salt crystallization and biological pollution (including proteins, bacteria and seaweed).

[0014] The mass ratio of the hydrogel matrix to the high-entropy alloy nanoparticles is 100:(5-20).

[0015] The hydrogel matrix includes a low-molecular-weight hydrogel component and a high-molecular-weight hydrogel component, and the mass ratio of the two is 100:(20-100), and the molecular weight of both ranges from 10,000 to 100,000, and the molecular weight of the high-molecular-weight hydrogel component is greater than that of the low-molecular-weight hydrogel component.

[0016] The preparation method of the high-strength biomimetic hydrogel evaporator with salt-resistant and anti-fouling functions includes the following steps:

[0017] Step 1: preparing high-entropy alloy nanoparticles and a biomimetic mold with the topological characteristics of a Nepenthes peristome;

[0018] Step 2: Functional component compounding and regulation: Dissolve the hydrogel matrix material in a binary co-solvent medium of water and organic solvent, and perform a heat activation treatment (50-80°C) to achieve complete dissolution. Then, under magnetic stirring, introduce the high-entropy alloy nanoparticles prepared in Step 1. Through the synergistic effect of mechanical shear dispersion and gradient temperature activation (90-120°C), achieve the dispersion of nano-phase. After uniform dispersion, finally form a composite hydrogel precursor solution with uniform dispersion characteristics of multiple scales;

[0019] Step 3: Flow control molding and low-temperature phase change crosslinking: When the composite hydrogel precursor solution obtained in Step 2 is in a molten flow state, it is precisely injected into a molding biomimetic mold cavity with a pitcher-shaped topological feature through injection technology, realizing the optimization of solution rheological properties and the replication of biomimetic structure. The mold is quickly transferred to a low-temperature phase change induced environment to trigger the molecular chain ordered assembly and crosslinking curing process. After physical crosslinking and curing, the high-entropy alloy-hydrogel composite evaporator with biomimetic microstructure is obtained after demolding after phase separation.

[0020] Step 4: Multi-level pore construction: The high-entropy alloy-hydrogel composite evaporator with biomimetic microstructure is subjected to freeze-thaw cycle and thermodynamic phase change strengthening treatment. After being immersed in deionized water for thawing after being frozen in liquid nitrogen, one freeze-thaw cycle is completed. After multiple freeze-thaw cycles, multi-level pore reconstruction is induced by ice crystal template effect, forming a mechanically enhanced biomimetic hydrogel evaporator. Thus, a high-strength biomimetic hydrogel evaporator with salt-resistant and antifouling functions is obtained.

[0021] In Step 1, the high-entropy alloy nanoparticle preparation method includes the following steps:

[0022] Step 1-1: Multiphase mechanical alloying pretreatment

[0023] High-purity (≥99.9%) transition group metal elements Fe, Ni, Ti, Cr, Mn, Cu, etc. with particle size ≤50μm are used as raw materials. High-energy mechanical alloying process is carried out in a three-dimensional planetary grinding system to achieve nanoscale compounding and obtain composite powder. The composite powder is prepared into a columnar precursor by cold isostatic pressing process.

[0024] The specific parameters for ball milling are: ball-to-material ratio 20:1, rotation speed 400-800rpm, ball milling time 12-36h, and ethanol as the organic dispersion medium to construct a layered composite powder with balanced atomic ratio. The pressure for cold isostatic pressing is 300MPa.

[0025] Step 1-2: Plasma-assisted non-equilibrium synthesis

[0026] The precursor is placed in a non-consumable electrode arc melting system, and a non-oxygen environment is established by three-stage vacuum degassing with a limit vacuum degree ≤5×10-3 Pa; a H2 / Ar mixed gas with a volume ratio of 1:9 is introduced as an ionization medium, and high-entropy alloy nanoparticles are obtained by pulse arc discharge treatment under the action of an electric current of 500 A and a voltage of 30 V for 5-30 min, so that in-situ nanocrystallization reconstruction is realized;

[0027] The key control points include: during the arc discharge treatment process, a liquid nitrogen auxiliary cooling system is used to maintain the substrate temperature in the phase transition critical interval of 7-10 DEG C, and the grain coarsening is inhibited by non-equilibrium phase transition; the product after the arc discharge treatment is exposed to air for 6-12 h, so that a passivation film is formed on the surface, and the high-entropy alloy nanoparticles with stable surface energy are obtained.

[0028] In step 1, the preparation method of the biomimetic mold with the topological characteristics of the Nepenthes peristome includes the following main contents:

[0029] Based on the biomimetic preparation principle, the three-dimensional morphological characteristics of the Nepenthes peristome region are obtained by low-temperature freeze drying combined with scanning electron microscopy technology, and a biomimetic topological structure with overlapping micro-pits is reconstructed by using three-dimensional modeling software; resin is used as raw material, and the biomimetic structure is printed by using light curing additive manufacturing technology; the post-processing procedure includes gradient solvent ultrasonic cleaning (isopropyl alcohol / ethanol) to remove unhardened resin residues, rapid drying with high-purity nitrogen, and then ultraviolet secondary curing to enhance the material cross-linking stability, so that the biomimetic mold with the topological characteristics of the Nepenthes peristome is obtained, that is, the biomimetic Nepenthes micro-nano structure with precise geometric characteristics. By combining reverse engineering of biological prototypes with precision manufacturing technology, the directional transport function of the Nepenthes peristome region liquid film is successfully reproduced.

[0030] In step 2, the hydrogel base is polyvinyl alcohol, which includes a low molecular weight hydrogel component and a high molecular weight hydrogel component, and the mass ratio of the two is 100:(20-100), and the molecular weight of both is 10000-100000; the molecular weight of the high molecular weight hydrogel component is greater than that of the low molecular weight hydrogel component;

[0031] The composite hydrogel precursor solution is a double-continuous phase solvent system, in which the mass ratio of the hydrogel base (a mixed system of polyvinyl alcohol with different molecular weights) to the high-entropy alloy nanoparticles (Fe-Ni-Ti-Cr-Mn-Cu system) is 100:(5-20);

[0032] The binary cosolvent medium is a cosolvent medium of water and dimethyl sulfoxide (DMSO), and dimethyl sulfoxide helps to reduce the freezing point of water and form a porous structure; the mass ratio of the organic solvent (dimethyl sulfoxide) to deionized water is 100:(2-8);

[0033] The mass ratio of the binary cosolvent medium to the hydrogel base is 100:(1-20);

[0034] A gradient temperature program is implemented in a high-temperature constant-temperature circulating oil bath device to prepare a composite hydrogel precursor solution:

[0035] The first stage: under magnetic stirring, the temperature is raised to 50-80℃ for 1-5h, so that the hydrogel matrix is completely dissolved in the binary cosolvent medium, and the hydroxyl bonding of the polyvinyl alcohol molecular chain of different molecular weights is activated; the second stage: after introducing high-entropy alloy nanoparticles, continue to raise the temperature to 90-120℃ for 1-5h, induce high-entropy alloy nanoparticles to disperse and coordinate with polyvinyl alcohol, and the chain segments of polyvinyl alcohol of different molecular weights are entangled; the whole process is carried out under magnetic stirring to ensure uniform dispersion of different phases;

[0036] Step 2: A biomimetic demolding system is constructed by a multi-stage molecular weight ratio regulation strategy. Two hydrogel precursors with different molecular weights are segmented and compounded in proportion, and the biomimetic topological structure fidelity control technology is used to optimize the demolding mechanical strength, ensuring the structural integrity and biomimetic microstructure replication accuracy;

[0037] In step 3, the physical crosslinking solidification is carried out at a low temperature of -20-4℃ to physically crosslink polyvinyl alcohol. The three-dimensional network pore size distribution is regulated by ice crystal template effect, and the crosslinking time is 8-18h to balance the crosslinking density and mechanical strength;

[0038] In step 4, the freeze-thaw cycle is carried out in a segmented manner to obtain a porous high-strength hydrogel evaporator. The substep temperature control is carried out in the liquid nitrogen rapid cooling stage: first, the precooling stage is handled at -80℃ for 1-100s, then the deep cooling stage is handled at -196℃ for 120-240s, and then the temperature is controlled to be thawed. The thawing process adopts a gradient heating method to heat to 25℃ at a rate of 1-40℃ / min to complete one freeze-thaw cycle. Through 2-5 freeze-thaw cycles, multi-stage pore reconstruction is completed to form a pore size gradient structure.

[0039] In step 4, first, deionized water is used to replace the organic solvent in the biomimetic microstructure high-entropy alloy-hydrogel composite evaporator to realize solvent replacement purification, and then the multi-stage pore construction is carried out.

[0040] The substrate is treated by dynamic permeation equilibrium method. Under constant pressure, the biomimetic microstructure high-entropy alloy-hydrogel composite evaporator obtained in step 3 is immersed in deionized water at room temperature of 20-30℃ for 5-24h to completely replace the organic solvent. The organic solvent elution replacement is completed at the same time to stabilize the three-dimensional network structure;

[0041] In step 4, after the construction of the multi-level channel is completed, surface activation encapsulation is carried out; the specific operation is that the biomimetic hydrogel evaporator after the construction of the multi-level channel is completed is placed in a constant temperature ion balance environment of a 26 DEG C deionized water system for activation, a stable protective interface is formed through self-assembly of a biomimetic surface hydration layer, and a high-strength biomimetic hydrogel evaporator with salt-resistant and antifouling functions is obtained.

[0042] The present application utilizes novel high-entropy alloy nanoparticles integrating efficient light-heat conversion of full-spectrum sunlight response and synergistic antibacterial ability, is inspired by the biomimetic structure at the peristome of Nepenthes, and regulates the mechanical strength of the hydrogel to construct a high-strength biomimetic hydrogel evaporator with salt-resistant and antifouling functions. Under the synergistic action of the high-entropy alloy and the biomimetic structure, the high-strength biomimetic hydrogel evaporator has a sunlight absorption rate of up to 98.5%, and the killing rate of gram-positive bacteria and gram-negative bacteria is more than 99% under irradiation. Due to the existence of the biomimetic structure, the evaporator has excellent resistance to marine fouling at different stages, and the surface does not appear salt crystallization during long-term service in seawater. The technical system deeply integrates biomimetic structure design, realizes the balance regulation of high strength and high-speed water transmission, and utilizes multifunctional and stable integrated high-entropy alloy nanoparticles, thereby breaking through the technical bottleneck of traditional evaporators in terms of light-heat efficiency and salt-resistant stability, and providing a theoretical model and engineering practice dual innovation for the development of an intelligent water treatment system facing industrial-level application.

[0043] Compared with the prior art, the present application has the following beneficial effects:

[0044] 1. The biomimetic structure of the peristome of Nepenthes is copied on the surface of the hydrogel evaporator, so that the surface has the ability of fast water transmission and water film formation. The existence of the flowing water film not only endows the evaporator with superhydrophilic characteristics, accelerates the water evaporation rate, endows the material surface with dynamic updating ability, but also plays a physical barrier role to reduce microbial adhesion and prevent the formation of marine biofouling. Meanwhile, salt ions are subjected to convection, diffusion and other ion exchange behaviors through the Mie scattering effect, so that salt crystallization is avoided.

[0045] 2. The present application utilizes high-entropy alloy nanoparticles that have realized the synergistic stable integration of light-heat response characteristics and broad-spectrum antibacterial performance as a light-heat material, so that they are used as one of the means for killing bacteria and other microorganisms. And synergistically with the multiple light reflection, refraction and micro-nano effects of the biomimetic structure, the light absorption is further enhanced. The coupling of the biomimetic structure and the multifunctional high-entropy alloy achieves the synergistic antifouling effect of chemical-physical-micro-nano structure, breaks through the efficiency bottleneck of the traditional single antifouling mode, and provides an innovative solution for microorganism killing with synergistic effect.

[0046] 3. The high-strength biomimetic hydrogel evaporator with anti-salt and anti-fouling functions provided by the present application has excellent mechanical properties, can not only accurately reproduce the biomimetic structure, but also can resist external forces to maintain the structure unchanged, has good stability to meet the application requirements under complex conditions, and through the synergistic regulation of molecular weight control and freeze-thaw cycle on the mechanical strength, the evaporator can ensure the above mechanical properties without affecting the water transmission effect, and the evaporation rate is further improved. BRIEF DESCRIPTION OF DRAWINGS

[0047] Figure 1 is an image of the high-entropy alloy nanoparticles in Example 3 of the present application displayed under the assistance of scanning transmission electron microscopy (HAADF-STEM) and energy dispersive X-ray spectroscopy (EDS);

[0048] Figure 2 is an X-ray photoelectron spectroscopy (XPS) graph of the sample; wherein, HEA-PVA(S) is the high-strength biomimetic hydrogel evaporator with anti-salt and anti-fouling functions in Example 3 of the present application, and PVA is the high-strength hydrogel evaporator in Comparative Example 1;

[0049] Figure 3 is an image of the high-strength biomimetic hydrogel evaporator with anti-salt and anti-fouling functions in Example 3 of the present application; wherein, (a) is a physical image of the biomimetic hydrogel evaporator, and (b) is a scanning electron microscope (SEM) image of the biomimetic hydrogel evaporator;

[0050] Figure 4 is an absorption spectrum curve graph of the sample; wherein, HEA is the high-entropy alloy nanoparticles in Example 3 of the present application, HEA-PVA(S) is the high-strength biomimetic hydrogel evaporator with anti-salt and anti-fouling functions in Example 3, PVA is the high-strength hydrogel evaporator in Comparative Example 1, and HEA-PVA is the high-strength photothermal hydrogel evaporator in Comparative Example 2;

[0051] Figure 5 is a water evaporation weight loss curve graph of the sample; wherein, HEA-PVA(S) is the high-strength biomimetic hydrogel evaporator with anti-salt and anti-fouling functions in Example 3 of the present application, PVA is the high-strength hydrogel evaporator in Comparative Example 1, and HEA-PVA is the high-strength photothermal hydrogel evaporator in Comparative Example 2;

[0052] Figure 6 is an anti-fluorescein-labeled bovine serum albumin (BSA-FITC) effect graph of the sample; wherein, (a) is the high-strength hydrogel evaporator in Comparative Example 1, (b) is the high-strength photothermal hydrogel evaporator in Comparative Example 2, and (c) is the high-strength biomimetic hydrogel evaporator with anti-salt and anti-fouling functions in Example 3, and the data marked in the graph is the fluorescence intensity of the adsorbed fluorescein-labeled bovine serum albumin (BSA-FITC);

[0053] Figure 7 : These are the anti-Pseudomonas aeruginosa effect diagrams of the samples; among them, (a) is the high-strength hydrogel evaporator in Comparative Example 1, (b) is the high-strength photothermal hydrogel evaporator in Comparative Example 2, (c) is the high-strength bionic hydrogel evaporator with salt resistance and anti-fouling function in Example 3, and (d) is the high-strength bionic hydrogel evaporator with salt resistance and anti-fouling function in Example 3 after 30 minutes of simulated sunlight irradiation treatment;

[0054] Figure 8 The anti-chlorella effect diagram of the samples; among them, (a) is the high-strength hydrogel evaporator in comparative example 1, (b) is the high-strength photothermal water gel evaporator in comparative example 2, and (c) is the high-strength bionic hydrogel evaporator with salt resistance and anti-fouling function in Example 3;

[0055] Figure 9 This is a diagram showing the water evaporation rate and salt resistance effect of a high-strength bionic hydrogel evaporator with salt resistance and anti-fouling functions in Example 3 of the present invention after 20 evaporation cycles in a simulated salt water environment;

[0056] Figure 10 : are stress-strain curves of the samples; wherein, (a) is a tensile stress-strain curve, HEA-PVA(S) is a high-strength bionic hydrogel evaporator with salt resistance and anti-fouling function in Example 3 of the present invention, and PVA is a high-strength hydrogel evaporator in Comparative Example 1; (b) is a compressive stress-strain curve of the high-strength bionic hydrogel evaporator with salt resistance and anti-fouling function in Example 3 of the present invention. DETAILED DESCRIPTION

[0057] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation methods, structures, features and effects of the present invention are described in detail below with reference to the accompanying drawings and preferred embodiments.

[0058] Experimental methods without specifying specific conditions are generally performed under conventional conditions, such as those described in textbooks and experimental manuals, or according to the conditions recommended by the manufacturer, which are well known or easily known to those skilled in the art. The following examples are only preferred embodiments of the present invention and do not limit the present invention. For those skilled in the art, the present invention may be subjected to various changes and modifications. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

[0059] Based on the cross-disciplinary technology integration strategy, the functional integration of high-performance photothermal evaporator is realized in the embodiment of the present application through the following innovative path: a three-dimensional interconnected porous composite hydrogel matrix (polyvinyl alcohol / high-entropy alloy composite system) is used to construct a gradient pore structure, and the pore size distribution and mechanical strength are controlled through a multi-stage freeze-thaw crosslinking process; the micro-nano structure at the peristome of Nepenthes and the gradient surface energy control technology are innovatively combined to form a certain thickness of directional flow water film at the evaporation interface, and the anti-salt crystallization property is realized through the Malan-goni effect; the specially designed surface engineering treatment makes the material have self-cleaning function, and no biological fouling occurs in continuous operation; Fe-Ni-Ti-Cr-Mn-Cu high-entropy alloy nanoparticles (HEA-NPs) are introduced into the photothermal conversion layer, and the full-spectrum absorption rate is further improved by means of d-d orbital transition effect and the synergistic effect of biomimetic structure. The synergistic use of micro-nano structure and high-entropy alloy breaks through the single means of traditional marine antifouling, realizes multi-level antifouling properties, and greatly improves the antifouling ability. The integrated scheme optimizes the biomimetic structure and cooperatively controls multiple physical fields, and finally prepares a high-strength biomimetic hydrogel evaporator with salt-resistant and antifouling functions.

[0060] The high-strength biomimetic hydrogel evaporator with salt-resistant and antifouling functions prepared in the embodiment has a Nepenthes peristome biomimetic structure, which is composed of a hydrogel matrix and high-entropy alloy nanoparticles; the high-entropy alloy nanoparticles have a solid solution structure and are uniformly dispersed in the hydrogel matrix, which is composed of Fe, Ni, Ti, Cr, Mn and Cu metal elements in a six-membered equiatomic configuration; the hydrogel matrix has a continuous phase structure and is composed of a high-molecular network skeleton formed by physical crosslinking and solidification of polyvinyl alcohol. The size of the biomimetic mold is about 2cm*2cm*0.5cm, and the mold cavity surface has a Nepenthes peristome micro-nano structure.

[0061] The present application will be further described below in conjunction with specific embodiments and drawings as follows:

[0062] Embodiment 1

[0063] In the high-strength biomimetic hydrogel evaporator with salt-resistant and antifouling functions prepared in this embodiment, the mass ratio of the hydrogel matrix and the high-entropy alloy nanoparticles is 100:10, the molecular weight of the low-molecular-weight hydrogel component in the hydrogel matrix is 10000, the molecular weight of the high-molecular-weight hydrogel component is 80000, and the mass ratio of the two is 100:20.

[0064] The specific preparation method includes the following steps:

[0065] Step 1: Preparation of high-entropy alloy nanoparticles and biomimetic mold with Nepenthes peristome topological characteristics.

[0066] The preparation method of high-entropy alloy nanoparticles is as follows:

[0067] Step 1-1: Pre-treatment by multi-phase mechanical alloying.

[0068] High purity (≥99.9%) transition group metal elements (Fe / Ni / Ti / Cr / Mn / Cu, particle size ≤50 μm) were used as raw materials to achieve nanoscale compounding by high-energy mechanical alloying process in a three-dimensional planetary grinding system. The composite powder was prepared into a cylindrical precursor by cold isostatic pressing preforming process.

[0069] The specific parameters for ball milling were as follows: ball-to-material ratio of 20:1, rotation speed of 600 rpm, and ball milling time of 12 h. Ethanol was used as an organic dispersion medium to construct a layered composite powder with balanced atomic ratio. Subsequently, a cold isostatic pressing preforming process (pressure of 300 MPa) was used to prepare a cylindrical precursor.

[0070] Step 1-2: Plasma-assisted non-equilibrium synthesis.

[0071] The precursor was placed in a non-consumable electrode arc melting system, and a three-stage vacuum degassing process (limiting vacuum degree ≤5×10 -3 Pa) was performed to establish an oxygen-free environment. Then, H2 / Ar mixed gas (volume ratio of 1:9) was introduced as the ionization medium, and a 10 min arc discharge treatment was carried out under the action of a pulse arc (current of 500 A, voltage of 30 V) to obtain high-entropy alloy nanoparticles, achieving in-situ nanocrystallization reconstruction.

[0072] The key control points included: during the arc discharge treatment process, a liquid nitrogen assisted cooling system was used to maintain the substrate temperature in the phase transition critical interval (ΔT = 7℃), and non-equilibrium phase transition was used to inhibit grain coarsening; after the arc discharge treatment, the product was exposed to air for 6 h to form a passivation film on the surface, and the high-entropy alloy nanoparticles with stable surface energy were obtained through oxidation layer passivation.

[0073] The preparation method of the biomimetic mold with the Nepenthes peristome topological characteristics is as follows:

[0074] Based on the principle of biomimetic preparation, the three-dimensional morphological characteristics of the Nepenthes peristome region were obtained by low-temperature freeze-drying combined with scanning electron microscopy technology, and a three-dimensional modeling software was used to reconstruct the biomimetic topological structure with overlapping micro-pits. The light-cured additive manufacturing technology was used to complete the printing of the biomimetic structure, and the post-processing procedures included gradient solvent ultrasonic cleaning (isopropyl alcohol / ethanol) to remove uncured resin residues, rapid drying with high-purity nitrogen, and then ultraviolet secondary curing to enhance the stability of material cross-linking. Finally, the biomimetic mold with the Nepenthes peristome topological characteristics was obtained, i.e., the biomimetic Nepenthes micro-nano structure with precise geometric characteristics. Through the combination of biological prototype reverse engineering and precision manufacturing technology, the directional transport function of the liquid film in the Nepenthes peristome region was successfully reproduced.

[0075] Step 2: Functional component compounding and regulation.

[0076] Two different molecular weight polyvinyl alcohol hydrogels are selected, the molecular weight of the low molecular weight polyvinyl alcohol hydrogel component is 10000, and the molecular weight of the high molecular weight polyvinyl alcohol hydrogel component is 80000; the mass ratio of the low molecular weight hydrogel component to the high molecular weight hydrogel component is 100:20, and the mixed polyvinyl alcohol hydrogel component is obtained to meet the demolding requirement.

[0077] 0.3g of the mixed polyvinyl alcohol hydrogel component is dissolved in a mixed solution of 0.2g of water and 5g of dimethyl sulfoxide (DMSO) binary cosolvent medium, and 0.03g of high-entropy alloy nanoparticles is added. After uniform dispersion, a composite hydrogel precursor solution is formed. The dispersion method is as follows: due to the requirement of mechanical properties, the method of gradient heating is adopted, the first stage: heating to 60℃ for 1h, so that the polyvinyl alcohol is completely dissolved; the second stage: after introducing the high-entropy alloy nanoparticles, continue to heat to 90℃ for 3h, the whole process is carried out in a magnetic stirring system to ensure uniform dispersion of different phases. After the polyvinyl alcohol and high-entropy alloy form a uniform phase, a composite hydrogel precursor solution is obtained.

[0078] Step 3: flow molding and low-temperature phase transition crosslinking.

[0079] When the composite hydrogel precursor solution obtained in step 2 is in a molten flow state, it is precisely injected into a forming biomimetic mold cavity with a pitcher-shaped mouth edge topological feature by injection technology;

[0080] The carrier liquid mold is quickly transferred to a low-temperature phase transition induction environment at-20℃, triggering the ordered assembly and crosslinking curing process of the molecular chain, so that the polyvinyl alcohol hydrogel component is physically crosslinked to form a solid gel. The low-temperature polymerization time is 10h, and after the physical crosslinking curing is completed, the high-entropy alloy-hydrogel composite evaporator with a biomimetic microstructure is demolded.

[0081] Step 4: Multi-stage pore construction.

[0082] First, solvent replacement purification is carried out, the specific method is as follows: the substrate is treated by dynamic osmotic balance method, and the high-entropy alloy-hydrogel composite evaporator with a biomimetic microstructure obtained in step 3 is immersed in deionized water at room temperature of 22℃ for 8h to completely replace the organic solvent, and the purified high-entropy alloy-hydrogel composite evaporator is obtained.

[0083] After purification, multi-level pore construction is carried out, and the specific method is as follows: the purified high-entropy alloy-hydrogel composite evaporator is subjected to freeze-thaw cycle, and stepwise temperature control is carried out in the liquid nitrogen rapid cooling stage: first, pre-cooling stage treatment: frozen at-80℃ for 10s, then deep cooling stage treatment: frozen at-196℃ for 150s, after deep cooling stage treatment, immersed in deionized water for temperature control thawing, gradient heating method is adopted, and the temperature is raised to 25℃ at a rate of 5℃ / min, and one freeze-thaw cycle is completed; freeze-thaw cycle 2 times, complete multi-level pore reconstruction, obtain mechanical enhanced high-entropy alloy-hydrogel composite evaporator.

[0084] After the construction of multi-level pores, surface activation packaging is carried out, and the specific method is as follows: the mechanical enhanced composite hydrogel evaporator is placed in a constant temperature ion balance environment (26℃ deionized water system) for activation, and a stable protective interface is formed by self-assembly of the biomimetic surface hydration layer to obtain a high-strength biomimetic hydrogel evaporator with salt-resistant and antifouling functions.

[0085] Example 2

[0086] In the high-strength biomimetic hydrogel evaporator with salt-resistant and antifouling functions prepared in this embodiment, the mass ratio of the hydrogel matrix and the high-entropy alloy nanoparticles is 100:8, the molecular weight of the low molecular weight hydrogel component in the hydrogel matrix is 15000, the molecular weight of the high molecular weight hydrogel component is 60000, and the mass ratio of the two is 100:40.

[0087] The specific preparation method comprises the following steps:

[0088] Step 1: Preparation of high-entropy alloy nanoparticles and biomimetic mold with Nepenthes peristome topological characteristics.

[0089] The preparation method of high-entropy alloy nanoparticles is as follows:

[0090] Step 1-1: Multiphase mechanical alloying pretreatment.

[0091] High-purity (≥99.9%) transition group metal elements (Fe / Ni / Ti / Cr / Mn / Cu, particle size ≤50μm) are used as raw materials, high-energy mechanical alloying process is carried out in a three-dimensional planetary grinding system, nanoscale composite is realized, and composite powder is obtained; the composite powder is prepared into a columnar precursor by cold isostatic pressing preforming process.

[0092] The specific parameters of ball milling are as follows: ball-to-material ratio 20:1, rotation speed 800rpm, ball milling time 15h, and ethanol as organic dispersion medium to construct layered composite powder with balanced atomic ratio. Then, a columnar precursor is prepared by cold isostatic pressing preforming process (pressure 300MPa).

[0093] Step 1-2: Plasma-assisted non-equilibrium synthesis.

[0094] The precursor is placed in a non-consumable electrode arc melting system, and an oxygen-free environment is established by three-stage vacuum degassing (limit vacuum degree ≤5×10 -3 Pa). H2 / Ar mixed gas (volume ratio 1:9) is introduced as ionization medium, and high-entropy alloy nanoparticles are obtained by 20 min arc discharge treatment under the action of pulse arc (current 500 A, voltage 30 V) to realize in-situ nanocrystallization reconstruction.

[0095] The key control points include: during the arc discharge treatment process, a liquid nitrogen assisted cooling system is used to maintain the substrate temperature in the phase transition critical interval (ΔT=8℃), and non-equilibrium phase transition is used to inhibit grain coarsening; after the arc discharge treatment, the product is exposed to air for 8h to form a passivation film on the surface, and the high-entropy alloy nanoparticles with stable surface energy are obtained by oxidation layer passivation.

[0096] The preparation method of the biomimetic mold with the topological characteristics of the Nepenthes peristome is as follows:

[0097] Based on the biomimetic preparation principle, the three-dimensional morphological characteristics of the peristome region of the Nepenthes are obtained by low-temperature freeze drying combined with scanning electron microscopy technology, and a biomimetic topological structure with overlapping micro-pits is reconstructed using three-dimensional modeling software. The biomimetic structure is printed using light-cured additive manufacturing technology, and the post-processing procedures include gradient solvent ultrasonic cleaning (isopropyl alcohol / ethanol) to remove uncured resin residues, rapid drying with high-purity nitrogen, and ultraviolet secondary curing to enhance the stability of material cross-linking. Finally, the biomimetic mold with the topological characteristics of the Nepenthes peristome is obtained, that is, the biomimetic Nepenthes micro-nano structure with precise geometric characteristics. Through the combination of biological prototype reverse engineering and precision manufacturing technology, the directional transport function of the liquid film in the peristome region of the Nepenthes is successfully reproduced.

[0098] Step 2: Functional component compounding and regulation.

[0099] Two polyvinyl alcohol hydrogels with different molecular weights are selected, the molecular weight of the low molecular weight polyvinyl alcohol hydrogel component is 15000, and the molecular weight of the high molecular weight polyvinyl alcohol hydrogel component is 60000; the mass ratio of the low molecular weight hydrogel component to the high molecular weight hydrogel component is 100:40, and the mixed polyvinyl alcohol hydrogel component is obtained to meet the demolding requirements.

[0100] 0.5 g of mixed polyvinyl alcohol hydrogel component is dissolved in a mixed solution of 0.5 g of water and 10 g of dimethyl sulfoxide (DMSO) binary co-solvent medium, and 0.04 g of high-entropy alloy nanoparticles is added. After uniform dispersion, a composite hydrogel precursor solution is formed. The dispersion method is as follows: due to the requirement of mechanical properties, a gradient heating method is adopted. The first stage: heat to 50°C for 2h to completely dissolve polyvinyl alcohol; the second stage: after introducing high-entropy alloy nanoparticles, continue to heat to 95°C for 1h, the whole process is carried out in a magnetic stirring system to ensure uniform dispersion of different phases. After polyvinyl alcohol and high-entropy alloy form a uniform phase, a composite hydrogel precursor solution is obtained.

[0101] Step 3: flow molding and low-temperature phase transition crosslinking.

[0102] When the composite hydrogel precursor solution obtained in step 2 is in a molten flow state, it is precisely injected into a molding mold cavity with a pitcher-shaped topological feature by injection technology;

[0103] The liquid carrier mold is quickly transferred to a low-temperature phase transition induction environment at -10°C, triggering the ordered assembly and crosslinking solidification process of the molecular chain, causing the polyvinyl alcohol hydrogel component to undergo physical crosslinking to form a solid gel. The low-temperature polymerization time is 10h, and after the physical crosslinking solidification is completed, the high-entropy alloy-hydrogel composite evaporator with a biomimetic microstructure is obtained by demolding.

[0104] Step 4: multi-level pore construction.

[0105] First, solvent replacement purification is performed. The specific method is as follows: the substrate is treated by dynamic osmotic balance method. Under constant pressure conditions, the high-entropy alloy-hydrogel composite evaporator with a biomimetic microstructure obtained in step 3 is immersed in deionized water at room temperature of 25°C for 24h to completely replace the organic solvent, and a purified high-entropy alloy-hydrogel composite evaporator is obtained.

[0106] After purification, multi-level pore construction is performed. The specific method is as follows: the purified high-entropy alloy-hydrogel composite evaporator is subjected to freeze-thaw cycles. The liquid nitrogen rapid cooling stage is implemented by stepwise temperature control: first, the pre-cooling stage is handled: frozen at -80°C for 50s, then the deep cooling stage is handled: frozen at -196°C for 210s, after the deep cooling stage treatment, immersed in deionized water for temperature control thawing, gradient heating method is adopted, heating to 25°C at a rate of 10°C / min, completing one freeze-thaw cycle; freeze-thaw cycle 4 times, complete multi-level pore reconstruction, obtain mechanical enhanced high-entropy alloy-hydrogel composite evaporator.

[0107] After constructing the multi-level channel, surface activation encapsulation is carried out, and the specific method is as follows: the mechanical enhancement type composite hydrogel evaporator is placed in a constant temperature ion balance environment (26℃ deionized water system) for activation, and a stable protective interface is formed by self-assembly of the biomimetic surface hydration layer to obtain a high-strength biomimetic hydrogel evaporator with salt-resistant and antifouling functions.

[0108] Example 3

[0109] In the high-strength biomimetic hydrogel evaporator with salt-resistant and antifouling functions prepared in this example, the mass ratio of the hydrogel matrix and the high-entropy alloy nanoparticles is 100:5, the molecular weight of the low-molecular-weight hydrogel component in the hydrogel matrix is 25000, the molecular weight of the high-molecular-weight hydrogel component is 50000, and the mass ratio of the two is 100:50.

[0110] The specific preparation method comprises the following steps:

[0111] Step 1: Preparation of high-entropy alloy nanoparticles and biomimetic mold with Nepenthes peristome topological characteristics.

[0112] The preparation method of the high-entropy alloy nanoparticles is as follows:

[0113] Step 1-1: Multiphase mechanical alloying pretreatment.

[0114] High-purity (≥99.9%) transition group metal elements (Fe / Ni / Ti / Cr / Mn / Cu, particle size ≤50 μm) are used as raw materials, and high-energy mechanical alloying process is carried out in a three-dimensional planetary grinding system to realize nanoscale compounding and obtain composite powder; the composite powder is prepared into a columnar precursor by cold isostatic pressing preforming process.

[0115] The specific parameters of ball milling are as follows: ball-to-material ratio 20:1, rotation speed 750 rpm, ball milling time 24 h, and ethanol as organic dispersion medium to construct layered composite powder with balanced atomic ratio. Then, a columnar precursor is prepared by cold isostatic pressing preforming process (pressure 300 MPa).

[0116] Step 1-2: Plasma-assisted non-equilibrium synthesis.

[0117] The precursor is placed in a non-consumable electrode arc melting system, and an oxygen-free environment is established by three-stage vacuum degassing (limiting vacuum degree ≤5×10 -3 Pa). Then, H2 / Ar mixed gas (volume ratio 1:9) is introduced as ionization medium, and 25 min arc discharge treatment is carried out under the action of pulse arc (current 500 A, voltage 30 V) to obtain high-entropy alloy nanoparticles and realize in-situ nanocrystallization reconstruction.

[0118] The key control points include: maintaining the substrate temperature in the phase transition critical interval (ΔT = 9℃) during the arc discharge treatment process by using a liquid nitrogen assisted cooling system to inhibit grain coarsening through non-equilibrium phase transition; exposing the product after the arc discharge treatment to air for 10h to form a passivation film on the surface, and obtaining high-entropy alloy nanoparticles with stable surface energy through oxidation layer passivation.

[0119] The preparation method of the biomimetic mold with the topological characteristics of the Nepenthes peristome is as follows:

[0120] Based on the principle of biomimetic preparation, the three-dimensional morphological characteristics of the peristome region of Nepenthes are obtained by low-temperature freeze-drying combined with scanning electron microscopy technology, and a biomimetic topological structure with overlapping micro-pits is reconstructed using three-dimensional modeling software. The biomimetic structure is printed using light-cured additive manufacturing technology, and the post-processing procedures include gradient solvent ultrasonic cleaning (isopropyl alcohol / ethanol) to remove uncured resin residues, rapid drying with high-purity nitrogen, and then secondary ultraviolet curing to enhance the stability of material cross-linking. Finally, a biomimetic mold with the topological characteristics of the Nepenthes peristome is obtained, i.e., a biomimetic Nepenthes micro-nano structure with precise geometric characteristics. Through the combination of biological prototype reverse engineering and precision manufacturing technology, the directional transport function of the liquid film in the peristome region of Nepenthes is successfully reproduced.

[0121] Step 2: Functional component compounding and regulation.

[0122] Two polyvinyl alcohol hydrogels with different molecular weights are selected, with the molecular weight of the low molecular weight polyvinyl alcohol hydrogel component being 25000 and the molecular weight of the high molecular weight polyvinyl alcohol hydrogel component being 50000. The mass ratio of the low molecular weight hydrogel component to the high molecular weight hydrogel component is 100:50, and a mixed polyvinyl alcohol hydrogel component is obtained to meet the demolding requirements.

[0123] 2g of the mixed polyvinyl alcohol hydrogel component is dissolved in a mixed solution of 0.25g of water and 10g of dimethyl sulfoxide (DMSO) binary cosolvent medium, and 0.1g of high-entropy alloy nanoparticles is added. After uniform dispersion, a composite hydrogel precursor solution is formed. The dispersion method is as follows: due to the requirement of mechanical properties, a gradient heating method is adopted. In the first stage, the temperature is raised to 80℃ for 1h to ensure complete dissolution of polyvinyl alcohol; in the second stage, after the introduction of high-entropy alloy nanoparticles, the temperature is continuously raised to 100℃ for 5h, and the whole process is carried out in a magnetic stirring system to ensure uniform dispersion of different phases. After the polyvinyl alcohol and high-entropy alloy form a uniform phase, a composite hydrogel precursor solution is obtained.

[0124] Step 3: Flow control molding and low-temperature phase transition cross-linking.

[0125] When the composite hydrogel precursor solution obtained in step 2 is in a molten flow state, it is precisely injected into the cavity of the molding mold with the topological characteristics of the Nepenthes peristome through injection technology;

[0126] The carrier liquid mold is quickly transferred to a low-temperature phase transition induction environment at-5℃, triggering the ordered assembly and cross-linking curing process of the molecular chain, causing the polyvinyl alcohol hydrogel composition to be physically cross-linked to form a solid gel, and the low-temperature polymerization time is 15h. After the physical cross-linking curing is completed, the high-entropy alloy-hydrogel composite evaporator with a biomimetic microstructure is obtained by demolding.

[0127] Step 4: Multi-level pore construction.

[0128] First, solvent replacement purification is performed, and the specific method is as follows: The substrate is treated by dynamic osmotic balance method, and the high-entropy alloy-hydrogel composite evaporator with a biomimetic microstructure obtained in step 3 is immersed in deionized water at room temperature of 24℃ for 15h to completely replace the organic solvent, thereby obtaining the purified high-entropy alloy-hydrogel composite evaporator.

[0129] After purification, multi-level pore construction is performed, and the specific method is as follows: The purified high-entropy alloy-hydrogel composite evaporator is subjected to freeze-thaw cycle, and stepwise temperature control is performed during liquid nitrogen rapid cooling stage: first, pre-cooling stage treatment is performed: freezing at-80℃ for 90s, then deep cooling stage treatment is performed: freezing at-196℃ for 140s, after deep cooling stage treatment, immerse in deionized water for temperature control thawing, gradient heating method is adopted, and the temperature is raised to 25℃ at a rate of 15℃ / min, and one freeze-thaw cycle is completed; freeze-thaw cycle is performed for 3 times, and multi-level pore reconstruction is completed, thereby obtaining the mechanical enhanced high-entropy alloy-hydrogel composite evaporator.

[0130] After constructing the multi-level pores, surface activation and encapsulation are performed, and the specific method is as follows: The mechanical enhanced composite hydrogel evaporator is placed in a constant temperature ion balance environment (deionized water system at 26℃) for activation, and a stable protective interface is formed by self-assembly of the biomimetic surface hydration layer, thereby obtaining the high-strength biomimetic hydrogel evaporator with salt-resistant and antifouling functions.

[0131] Comparative Example 1

[0132] The high-strength hydrogel evaporator prepared in this comparative example does not contain high-entropy alloy nanoparticles and does not have a pitcher plant biomimetic structure on the surface. The molecular weight of the low molecular weight hydrogel component in the hydrogel matrix is 25000, the molecular weight of the high molecular weight hydrogel component is 50000, and the mass ratio of the two is 100:50.

[0133] The specific preparation method includes the following steps:

[0134] Step 1: No high-entropy alloy nanoparticles and biomimetic mold are prepared.

[0135] Step 2: Functional component compounding and regulation.

[0136] Two different molecular weight polyvinyl alcohol hydrogels are selected, the molecular weight of the low molecular weight polyvinyl alcohol hydrogel component is 25000, and the molecular weight of the high molecular weight polyvinyl alcohol hydrogel component is 50000; the mass ratio of the low molecular weight hydrogel component to the high molecular weight hydrogel component is 100:50, and a mixed polyvinyl alcohol hydrogel component is obtained to meet the demolding requirements.

[0137] 2g of the mixed polyvinyl alcohol hydrogel component is dissolved in a mixed solution of 0.25g of water and 10g of dimethyl sulfoxide (DMSO) binary co-solvent medium, and after uniform dispersion, a composite hydrogel precursor solution is formed. The dispersion method is as follows: due to the requirement of mechanical properties, the method of gradient heating is adopted, the first stage: heating to 80℃ for 1h, so that the polyvinyl alcohol is completely dissolved; the second stage: continue to heat to 100℃ for 5h, the whole process is carried out in a magnetic stirring system to ensure uniform dispersion of different phases. After the different molecular weight polyvinyl alcohol forms a uniform phase, the composite hydrogel precursor solution is obtained.

[0138] Step 3: flow molding and low-temperature phase transition crosslinking.

[0139] When the composite hydrogel precursor solution is in a molten flow state, it is injected into a molding mold cavity made of ordinary polytetrafluoroethylene material by injection technology, and the mold shape is a cuboid with a size of 2cm×2cm×0.5cm;

[0140] The liquid mold is quickly transferred to a low-temperature phase transition induction environment of-5℃, triggering the ordered assembly and crosslinking solidification process of the molecular chain, so that the polyvinyl alcohol hydrogel component is physically crosslinked to form a solid gel, and the low-temperature polymerization time is 15h. After the physical crosslinking solidification is completed, the hydrogel evaporator is demolded.

[0141] Step 4: Multi-stage pore construction.

[0142] First, solvent replacement purification is carried out, the specific method is as follows: the substrate is treated by dynamic osmotic balance method, and the hydrogel evaporator obtained in step 3 is immersed in deionized water at 24℃ under constant pressure conditions for 15h to replace the organic solvent completely, and a purified hydrogel composite evaporator is obtained.

[0143] After purification, multi-stage pore construction is carried out, the specific method is as follows: the purified hydrogel composite evaporator is subjected to freeze-thaw cycle, and the liquid nitrogen rapid cooling stage is implemented by stepwise temperature control: first, the precooling stage is handled: frozen at-80℃ for 90s, then the deep cooling stage is handled: frozen at-196℃ for 140s, after the deep cooling stage treatment, immerse in deionized water for thawing, and adopt gradient heating method, heating to 25℃ at a rate of 15℃ / min, complete one freeze-thaw cycle; freeze-thaw cycle 3 times, obtain high-strength hydrogel evaporator.

[0144] Comparative Example 2

[0145] The high-strength photothermal hydrogel evaporator prepared in this comparative example does not have a Nepenthes biomimetic structure, and the mass ratio of the hydrogel matrix and the high-entropy alloy nanoparticles is 100:5. The molecular weight of the low-molecular-weight hydrogel component in the hydrogel matrix is 25000, and the molecular weight of the high-molecular-weight hydrogel component is 50000. The mass ratio of the two is 100:50.

[0146] The specific preparation method includes the following steps:

[0147] Step 1: Preparation of high-entropy alloy nanoparticles.

[0148] Step 1-1: Multiphase mechanical alloying pretreatment.

[0149] High-purity (≥99.9%) transition group metal elements (Fe / Ni / Ti / Cr / Mn / Cu, particle size ≤50 μm) are used as raw materials, and high-energy mechanical alloying process is carried out in a three-dimensional planetary grinding system to realize nanoscale compounding and obtain composite powder. The composite powder is prepared into a columnar precursor by cold isostatic pressing preforming process.

[0150] The specific parameters of ball milling are as follows: ball-to-material ratio 20:1, rotation speed 750 rpm, ball milling time 24 h, and ethanol as organic dispersion medium to construct a layered composite powder with balanced atomic ratio. Then, a columnar precursor is prepared by cold isostatic pressing preforming process (pressure 300 MPa).

[0151] Step 1-2: Plasma-assisted non-equilibrium synthesis.

[0152] The precursor is placed in a non-consumable electrode arc melting system, and a non-oxygen environment is established by three-stage vacuum degassing (limiting vacuum degree ≤5×10 -3 Pa). Then, H2 / Ar mixed gas (volume ratio 1:9) is introduced as ionization medium, and 25 min arc discharge treatment is carried out under the action of pulse arc (current 500 A, voltage 30 V) to obtain high-entropy alloy nanoparticles, realizing in-situ nanocrystallization reconstruction.

[0153] The key control points include: during the arc discharge treatment process, a liquid nitrogen assisted cooling system is used to maintain the substrate temperature in the phase transition critical region (ΔT=9℃), and non-equilibrium phase transition is used to inhibit grain coarsening; the product after arc discharge treatment is exposed to air for 10 h to form a passivation film on the surface, and the high-entropy alloy nanoparticles with stable surface energy are obtained by oxidation layer passivation.

[0154] Step 2: Functional component compounding and regulation.

[0155] Two different molecular weight polyvinyl alcohol hydrogels were selected, the molecular weight of the low molecular weight polyvinyl alcohol hydrogel component was 25000, and the molecular weight of the high molecular weight polyvinyl alcohol hydrogel component was 50000; the mass ratio of the low molecular weight hydrogel component to the high molecular weight hydrogel component was 100:50, and a mixed polyvinyl alcohol hydrogel component was obtained to meet the demolding requirements.

[0156] 2g of the mixed polyvinyl alcohol hydrogel component was dissolved in a mixed solution of 0.25g of water and 10g of dimethyl sulfoxide (DMSO) binary cosolvent medium, and 0.1g of high-entropy alloy nanoparticles was added. After uniform dispersion, a composite hydrogel precursor solution was formed. The dispersion method is as follows: due to the requirement of mechanical properties, the method of gradient heating is adopted, the first stage: heating to 80℃ for 1h, the second stage: continue to heat to 100℃ for 5h, the whole process is carried out in a magnetic stirring system to ensure uniform dispersion of different phases. After the polyvinyl alcohol and high-entropy alloy form a uniform phase, the composite hydrogel precursor solution is obtained.

[0157] Step 3: flow molding and low-temperature phase change crosslinking. When the composite hydrogel precursor solution obtained in step 2 is in a molten flow state, it is injected into a common polytetrafluoroethylene material forming mold cavity through injection technology. The mold shape is a cuboid with dimensions of 2cm×2cm×0.5cm.

[0158] The liquid mold is quickly transferred to a low-temperature phase transition induction environment at -5℃, triggering the ordered assembly and crosslinking solidification process of the molecular chain, causing the polyvinyl alcohol hydrogel component to undergo physical crosslinking to form a solid gel. The low-temperature polymerization time is 15h, and after the physical crosslinking solidification is completed, the high-entropy alloy-hydrogel composite evaporator is demolded.

[0159] Step 4: multi-level pore construction.

[0160] First, solvent replacement purification is carried out. The specific method is as follows: the substrate is treated by dynamic osmotic balance method, and the high-entropy alloy-hydrogel composite evaporator obtained in step 3 is immersed in deionized water at 24℃ for 15h to completely replace the organic solvent, and the purified high-entropy alloy-hydrogel composite evaporator is obtained.

[0161] After purification, multi-level pore construction is carried out. The specific method is as follows: the purified high-entropy alloy-hydrogel composite evaporator is subjected to freeze-thaw cycle, and the liquid nitrogen rapid cooling stage is implemented by stepwise temperature control: first, the precooling stage treatment is carried out: freezing at -80℃ for 90s, then the deep cooling stage treatment is carried out: freezing at -196℃ for 140s, after the deep cooling stage treatment, immerse in deionized water for thawing, adopt gradient heating method, heating to 25℃ at a rate of 15℃ / min, complete one freeze-thaw cycle; freeze-thaw cycle 3 times, obtain high-strength photothermal hydrogel evaporator.

[0162] Performance analysis:

[0163] 1. Morphology analysis of high-entropy alloy nanoparticles: According to the results of scanning transmission electron microscopy analysis (HAADF-STEM) and energy dispersive spectroscopy element distribution characterization (EDS), the multi-component high-entropy alloy nanoparticles synthesized by the arc melting method in the present application exhibit a geometrically regular near-spherical morphology, with uniform particle size distribution and smooth surface, as shown in Figure 1 Atomic scale element distribution analysis shows that the component metals in the nanoparticles exhibit a disordered solid solution state in three-dimensional space, and no element segregation or phase separation phenomenon is observed.

[0164] 2. XPS survey analysis: As can be seen from Figure 2 The high-strength biomimetic hydrogel evaporator with salt-resistant and antifouling functions in Example 3 successfully combines high-entropy alloy nanoparticles.

[0165] 3. SEM image analysis: As can be seen from the physical map of Figure 3 (a) and the morphology of the SEM image of Figure 3 (b), the surface of the high-strength biomimetic hydrogel evaporator with salt-resistant and antifouling functions in Example 3 exhibits a structure of multiple rows of overlapping pits, which is consistent with the biological array arrangement characteristics of the Nepenthes peristome, indicating that the high-strength biomimetic hydrogel evaporator with salt-resistant and antifouling functions in Example 3 of the present application successfully replicates the Nepenthes biomimetic structure.

[0166] 4. Solar absorption spectrum analysis: The absorbance of the sample in the 300nm-2500nm wavelength range was tested using a UV-Vis-NIR spectrophotometer (UV-3600i) equipped with an integrating sphere accessory. After the instrument was preheated and stabilized, first, barium sulfate tablets were used as a reference for baseline correction. After the sample was uniformly filled and pressed into a tablet, it was placed in the sample cell. Set the scanning parameters: wavelength range 300nm-2500nm, slit width 20nm, data point interval 1nm, measurement mode reflectance (R). Start scanning, the instrument automatically uses deuterium lamp in the ultraviolet region and halogen tungsten lamp in the visible-near infrared region as light source. The detector collects the sample reflection light signal in real time and converts it into absorbance data output.

[0167] According to Figure 4The high-strength biomimetic hydrogel evaporator with salt-resistant antifouling function in Example 3 of the present application successfully combines high-entropy alloy nanoparticles, combines high-entropy alloy nanoparticles and biomimetic Nepenthes marginal structure, and exhibits significant optimization of optical performance: high-entropy alloy realizes synergistic light absorption enhancement in a wide spectral range of 300 nm-2500 nm through the d-d band transition mechanism of 3d transition metals; at the same time, the micro-nano structure designed on the surface of the biomimetic Nepenthes reduces the solar reflectivity through multiple light scattering effects, and forms a coupling effect with the light absorption characteristics of high-entropy alloy nanoparticles, and finally achieves an ultra-high solar absorption rate of 98.5%.

[0168] 5. Water evaporation mass loss curve analysis: A xenon lamp light source (simulating AM 1.5G single solar irradiance) and a precision analytical balance with an accuracy of 0.0001 g were used to test the evaporation rate of distilled water. After the sample was stabilized in a constant temperature environment, the initial mass was recorded. Turn on the light source to ensure uniform heating of the sample surface, and place it on the precision balance. The balance automatically outputs real-time mass data every minute. Through the continuously recorded time-mass change curve, the mass loss of deionized water per unit time is calculated, and combined with the surface area of the sample, the water evaporation rate is obtained.

[0169] Figure 5 The absolute value of the slope of each curve represents the water evaporation rate, and the evaporation rate of Example 3 is 2.85 kg·m -2 ·h -1 The high-strength biomimetic hydrogel evaporator with salt-resistant antifouling function in Example 3 exhibits excellent water evaporation performance: high-entropy alloy nanoparticles realize light-to-heat conversion efficiency improvement in a wide spectral range through the synergistic inter-band transition effect of 3d transition metals, which makes the evaporation rate increase by 42.5% compared with the high-strength hydrogel evaporator in Comparative Example 1 (2.0 kg·m -2 ·h -1 ); and the micro-nano structure designed on the surface of the biomimetic Nepenthes suppresses reflection and forms a continuous directional water film through multiple light scattering, which further increases the evaporation rate by 18.8% compared with the high-strength photothermal hydrogel evaporator in Comparative Example 2 (2.4 kg·m -2 ·h -1 ). This performance improvement is due to the dual synergistic mechanism of material-structure: the enhanced localized surface plasmon resonance effect of high-entropy alloy and the rapid water replenishment-evaporation dynamic balance induced by biomimetic microstructure, which together break through the light absorption and mass transfer limitations of traditional evaporators.

[0170] 6. Anti-fouling effect analysis: Material surface anti-biofouling performance evaluation: all samples were pre-sterilized by UV for 30 minutes. Anti-protein adsorption experiment: after the sample was co-cultured with 1 mg / mL BSA / FITC solution for 24 hours, it was washed with PBS buffer and vortexed with water, and CLSM was used for observation (Ex / Em = 493 / 550 nm). Anti-bacterial experiment: under the condition of no light, the sample was immersed in Pseudomonas aeruginosa or Bacillus vietnamensis diluted bacteria solution (37℃, 7 days), then washed with PBS buffer, and the anti-bacterial activity was quantified by plate counting method. Anti-algae experiment: after the sample was immersed in Chlorella vulgaris or Triangular algae diluted algae solution (22℃, 3000Lux, 7 days), it was washed with PBS buffer, and CLSM was used to observe the adhesion of the fouling organisms on the material surface (Ex / Em = 493 / 550 nm).

[0171] From Figure 6 (a), Figure 6 (b) and Figure 6 (c), it can be known that the high-strength biomimetic hydrogel evaporator prepared by the present application can resist bovine serum albumin to a certain extent; from Figure 7 (a), Figure 7 (b), Figure 7 (c) and Figure 7 (d), it can be known that the high-strength biomimetic hydrogel evaporator can resist Pseudomonas aeruginosa and has a certain bactericidal effect, and the effect is particularly obvious under light conditions; from Figure 8 (a), Figure 8 (b) and Figure 8 (c), it can be known that the high-strength biomimetic hydrogel evaporator can resist the adhesion of microorganisms such as Chlorella vulgaris; it can be seen that the high-strength biomimetic hydrogel evaporator has the anti-salt and anti-fouling functions after having the Nepenthes biomimetic surface, and due to the construction of the super-hydrophilic surface and the existence of the flowing water film, the anti-fouling ability is further enhanced. After the high-strength biomimetic hydrogel evaporator with anti-salt and anti-fouling functions in Example 3 is irradiated under one sunlight intensity (other conditions are the same as those in the sample anti-bacterial experiment), the anti-bacterial rate is further improved to more than 99% due to the synergistic bactericidal effect of the high-entropy alloy.

[0172] 7. Anti-salt effect analysis: A xenon lamp light source (simulating AM 1.5G single solar irradiance) and a precision analytical balance with a precision of 0.0001g are used to test the salt water evaporation rate. After the sample is stabilized in a constant temperature environment, the initial mass is recorded. Turn on the light source to ensure uniform heating of the sample surface, and place it on the precision balance. The balance automatically outputs real-time mass data every minute. By continuously recording the time-mass change curve, the mass loss of the simulated salt water (3.5wt.% NaCl solution) per unit time is calculated, and then combined with the surface area of the sample, the water evaporation rate is obtained. At the same time, optical photographs of the sample surface are taken at the time of 1, 5, 10, 15 and 20 cycles of evaporation, representing the salt crystallization condition.

[0173] By Figure 9 Analysis shows that as the number of salt evaporation cycles increases, no salt crystals appear on the surface of the sample, the Nepenthes biomimetic structure remains intact, and the water evaporation rate of the high-strength biomimetic hydrogel evaporator with salt-resistant and anti-fouling functions of Example 3 is basically constant at 2.45 kg·m -2 ·h -1 , with good durability and salt resistance.

[0174] 8. Mechanical property analysis: dumbbell-shaped samples (national standard type II) were prepared according to the ratio of hydrogel matrix and high-entropy alloy in Example 3 and the ratio of hydrogel in Comparative Example 1, and uniaxial tension was carried out at a rate of 10 mm / min until fracture, and the instrument recorded the stress-strain curve, fracture strength and elongation rate simultaneously; cylindrical samples (Φ20x20mm) were prepared according to the ratio of hydrogel matrix and high-entropy alloy in Example 3, and compression was carried out at a rate of 10 mm / min to 80% strain, and the compression stress-strain curve was obtained. The test was carried out in the same environment, the clamp was treated with anti-skid, the compression interface was coated with silicone oil to reduce friction, each group of parallel tests was ≥5 samples and abnormal values were removed.

[0175] By Figure 10 (a) Tensile stress-strain curve analysis shows that compared with the hydrogel evaporator of Comparative Example 1, the tensile strength of the hydrogel evaporator of Example 3 with high-entropy alloy nanoparticles is increased by about 60%, and the mechanical strength is greatly improved; by Figure 10 (b) Compression stress-strain curve analysis shows that the high-strength biomimetic hydrogel evaporator with salt-resistant and anti-fouling functions of Example 3 has a maximum compressive strength of more than 1 MPa, which belongs to high-strength hydrogel in the field of hydrogel evaporators, and reaches the strength to resist external forces and maintain its stability.

Claims

1. A bionic hydrogel evaporator with salt resistance and anti-fouling function, characterized in that: The surface of the bionic hydrogel evaporator has a bionic structure of the rim of a pitcher plant, and is composed of a hydrogel matrix and high entropy alloy nanoparticles; The high entropy alloy nanoparticles are composed of Fe, Ni, Ti, Cr, Mn, and Cu metal elements in equal atomic percentages; the mass ratio of the hydrogel matrix to the high entropy alloy nanoparticles is 100:(5-20); the high entropy alloy nanoparticles are uniformly dispersed in the hydrogel matrix; the hydrogel matrix has a continuous phase structure and is formed by physical crosslinking and curing of polyvinyl alcohol; the hydrogel matrix includes a low molecular weight hydrogel component and a high molecular weight hydrogel component, the mass ratio of the low molecular weight hydrogel component and the high molecular weight hydrogel component is 100:(20-100), and the molecular weights of the two components are both in the range of 10,000-100,000; When the bionic hydrogel evaporator is used for seawater desalination, it can resist salt crystals formed during the seawater desalination process and biological pollution in the seawater, wherein the biological pollution includes protein, bacteria and algae.

2. The method for preparing the bionic hydrogel evaporator with salt resistance and antifouling function according to claim 1, characterized in that: Includes the following: Step 1: Prepare high entropy alloy nanoparticles and a bionic mold with the rim structure of the pitcher plant; Step 2: Functional component compounding and regulation: dissolving the hydrogel matrix in a binary co-solvent of water and an organic solvent, introducing high entropy alloy nanoparticles, and obtaining a composite hydrogel precursor solution; Step 3: Fluid control molding and low-temperature phase change crosslinking: The composite hydrogel precursor solution is injected into a bionic mold with a pitcher plant rim structure while in a molten flow state. After physical crosslinking and curing, a high-entropy alloy-hydrogel composite evaporator with a bionic microstructure is obtained; Step 4: Multi-level pore construction: The high-entropy alloy-hydrogel composite evaporator with a bionic microstructure is subjected to a freeze-thaw cycle. After the composite evaporator is quickly frozen with liquid nitrogen, it is immersed in deionized water for temperature-controlled thawing to complete a freeze-thaw cycle. After several freeze-thaw cycles, multi-level pore reconstruction is formed to obtain a bionic hydrogel evaporator with salt resistance and anti-fouling functions.

3. The method for preparing a bionic hydrogel evaporator with salt resistance and antifouling function according to claim 2, characterized in that: In step 1: The method for preparing the high entropy alloy nanoparticles comprises the following steps: Step 1-1: Multiphase mechanical alloying pretreatment: Fe, Ni, Ti, Cr, Mn, and Cu metal powders are used as raw materials and ball milled to achieve nano-scale composite to obtain composite powders; the composite powders are prepared into precursors by cold isostatic pressing preforming process; Step 1-2: Plasma-assisted non-equilibrium synthesis: The precursor is placed in a non-consumable electrode arc melting system to establish an oxygen-free environment. A H2 / Ar mixed gas is introduced as an ionizing medium. Arc discharge treatment is performed for 5 minutes to 30 minutes under the action of a pulsed arc with a current of 500A and a voltage of 30V to obtain high-entropy alloy nanoparticles. The method for preparing the bionic mold having the rim structure of a pitcher plant comprises the following main contents: Based on the three-dimensional morphological characteristics of the rim of the pitcher plant, a bionic topological structure with overlapping micro-pits was designed; using resin as raw material, the bionic structure was printed using photocuring additive manufacturing technology, and the uncured resin residue was removed. After secondary curing, a bionic mold with the micro-nano structure of the pitcher plant rim was obtained.

4. The method for preparing a bionic hydrogel evaporator with salt resistance and antifouling function according to claim 3, characterized in that: In step 1-1, the main parameters of ball milling are: ball-to-material ratio 20:1, rotation speed 400 rpm-800 rpm, and ball milling time 12 h-36 h; In step 1-2, the substrate temperature is maintained at 7°C-10°C during the arc discharge treatment. The product after the arc discharge treatment is exposed to air for 6h-12h to form a passivation film on its surface, thereby obtaining high-entropy alloy nanoparticles with stable surface energy.

5. The method for preparing a bionic hydrogel evaporator with salt resistance and antifouling function according to claim 2, characterized in that: In step 2: the hydrogel matrix is ​​polyvinyl alcohol, including a low molecular weight hydrogel component and a high molecular weight hydrogel component, the mass ratio of the two is 100:(20-100), and the molecular weight range of both is 10,000-100,000; the mass ratio of the hydrogel matrix to the high entropy alloy nanoparticles is 100:(5-20); the mass ratio of the binary eutectic medium to the hydrogel matrix is ​​100:(1-20).

6. The method for preparing a bionic hydrogel evaporator with salt resistance and antifouling function according to claim 2, characterized in that: In step 2, the composite hydrogel precursor solution is prepared using a gradient temperature program; The first stage: heating to 50-80℃ and keeping it for 1-5 hours to completely dissolve the hydrogel matrix in the binary co-solvent medium; The second stage: after the high entropy alloy nanoparticles are introduced, the temperature is continued to be raised to 90° C.-120° C. and kept for 1 h-5 h, and the composite hydrogel precursor solution is obtained after being evenly dispersed.

7. The method for preparing a bionic hydrogel evaporator with salt resistance and antifouling function according to claim 2, characterized in that: In step 3, the physical crosslinking curing is to perform physical crosslinking of polyvinyl alcohol in a low temperature environment of -20°C to 4°C, and the crosslinking time is 8h to 18h.

8. The method for preparing a bionic hydrogel evaporator with salt resistance and antifouling function according to claim 2, characterized in that: In step 4, the freeze-thaw cycle refers to pre-cooling treatment by first quick freezing at -80°C for 1s-100s using liquid nitrogen, then freezing at -196°C for 120s-240s for cryogenic treatment, and thawing under controlled temperature after cryogenic treatment. The thawing process adopts a gradient temperature rise method at a rate of 1°C / min-40°C / min to 25°C to complete a freeze-thaw cycle; the multi-level pore reconstruction is completed through 3-5 freeze-thaw cycles to form a pore gradient structure.

9. The method for preparing a bionic hydrogel evaporator with salt resistance and antifouling function according to claim 2, characterized in that: In step 4, the organic solvent in the high entropy alloy-hydrogel composite evaporator of the biomimetic microstructure is first replaced with deionized water to achieve solvent replacement purification, thereby obtaining a purified high entropy alloy-hydrogel composite evaporator, and then multi-stage pore construction is performed. After the multi-stage pore construction is completed, surface activation packaging is performed; Specifically, the high entropy alloy-hydrogel composite evaporator with a biomimetic microstructure is immersed in deionized water at 20° C. to 30° C. for 5 h to 24 h until the organic solvent is completely replaced, thereby obtaining a purified high entropy alloy-hydrogel composite evaporator; The bionic hydrogel evaporator after the multi-level channel construction is placed in a room temperature deionized water system for surface activation and encapsulation, and a stable protective interface is formed through the self-assembly of the bionic surface hydration layer to obtain the bionic hydrogel evaporator with salt resistance and anti-fouling functions.

Images