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

Abstract

The invention belongs to the field of seawater desalination, and particularly relates to a bionic hydrogel evaporator with salt-resistant and antifouling functions and a preparation method of the bionic hydrogel evaporator. In order to solve the problem that salt crystals and marine biofouling can be generated on the surface of an existing hydrogel evaporator in the seawater evaporation process, high-entropy alloy nano-particles and hydrogel are homogenized and compounded, the molecular weight range of the hydrogel is 10000-100000, the mass ratio of a hydrogel matrix to the high-entropy alloy nano-particles is 100: (5-20), and the high-entropy alloy nano-particles and the hydrogel are uniformly mixed. In-situ cross-linking curing is carried out in a bionic mold with a common nepenthes mouth edge micro-nano structure, the cross-linking density and the pore size of hydrogel are changed by regulating and controlling the freezing and thawing cycle times and the operation time, so that the mechanical strength capable of resisting external force and the rapid water transmission capacity are obtained, and finally the bionic hydrogel evaporator with the salt-resistant and antifouling functions is obtained.

Description

Technical Field

[0001] The present invention belongs to the field of seawater desalination, and in particular relates to a bionic hydrogel evaporator with salt resistance and anti-fouling functions and a preparation method thereof. Background Art

[0002] Approximately 97.3% of Earth's water resources are seawater. Traditional desalination technologies, such as reverse osmosis and distillation, are hindered by high energy consumption and complex equipment, hindering their widespread adoption. Furthermore, these solutions are highly centralized, making desalination in dispersed areas impossible. Against this backdrop, photothermal interfacial evaporation technology has garnered widespread attention due to its advantages, including zero carbon emissions, minimal centralized requirements, and efficient use of renewable energy. By constructing a photothermal conversion layer at the water-air interface using photothermal materials, this technology achieves rapid evaporation with low heat loss and is considered a revolutionary solution for desalination. Porous hydrogel-based photothermal interfacial evaporators, known for their strong water activation and rapid water transport, have become a research hotspot.

[0003] When hydrogel evaporators are used for seawater desalination, salt crystallization on their surfaces during the evaporation process and biofouling by marine organisms are two key factors limiting their widespread service. During the photothermal conversion process, salt accumulation at the evaporation interface forms salt crystals, which coat the surface of the photothermal material, blocking light absorption and water vapor transmission. The presence of salt crystals makes it difficult for the evaporator to achieve both efficient heat transfer and salt migration. Furthermore, fouling organisms (such as bacteria and algae) in seawater begin to attach and parasitize the material upon contact with seawater. These fouling organisms, through metabolic activity, form biofilms, leading to pore blockage and corrosion. Therefore, both salt crystals formed during the desalination process and biofouling caused by the attachment of marine organisms will eventually adhere to the evaporator, blocking water transfer pores, reducing evaporation rates, and causing evaporator failure. Furthermore, mechanical strength to withstand environmental forces and maintain structural integrity is a key performance requirement for hydrogel evaporators. Therefore, developing a high-strength hydrogel evaporator with high photothermal conversion efficiency, high seawater desalination rate, and salt resistance and anti-fouling functions is an effective way to overcome the limitations of large-scale application of water evaporators.

[0004] Photothermal conversion materials play a central role in the design and optimization of solar interfacial evaporators. They convert solar energy into localized heat energy through the photothermal conversion effect, achieving efficient solar-thermal energy conversion. The light absorption efficiency, thermal conductivity, and chemical stability of these materials directly determine the energy conversion efficiency and long-term operational stability of the evaporator. Based on the needs of marine antifouling engineering, compared with the traditional strategy of adding antimicrobial agents to the system, giving the photothermal conversion layer inherent antibacterial function through material design is a more sustainable solution. However, traditional photothermal conversion materials (such as carbon-based and precious metal nanomaterials) lack inherent antibacterial properties and are difficult to meet the needs of long-term stable operation in marine environments. Summary of the Invention

[0005] To address the key technical challenges currently faced, this paper proposes a high-strength biomimetic hydrogel evaporator with salt and antifouling properties and its preparation method, aiming to overcome the core shortcomings of existing technologies. By designing a biomimetic structure and optimizing the preparation process, this technical solution enables rapid prototyping and manufacturing. The result is a biomimetic hydrogel evaporator with a broad-spectrum photothermal response, high desalination efficiency, and durable antifouling properties. This effectively ensures the long-term stable operation of the evaporation device under harsh operating conditions, overcoming the technical barriers to the industrialization and promotion of traditional photothermal evaporation devices.

[0006] The rim structure of the pitcher plant is composed of a large number of overlapping, inclined micro-pits with sharp cantilever structures. This allows for rapid, energy-free, unidirectional transport of liquids across the solid surface, forming a confined water film. The combined effects of the water film generated by the micro-pits and the rapid water transport generated by the Laplace pressure gradient give the pitcher plant biomimetic surface a super-hydrophilic effect and the Marangoni effect, offering new approaches for preventing microbial attachment and ion exchange. The flowing water film effectively disrupts the interaction between marine organisms and the surface, reducing microbial attachment. Furthermore, thanks to the combined effects of the hydrophilic hydrogel substrate and the biomimetic structure, the flowing water film dynamically renews itself during evaporation, replenishing water in localized areas of elevated salt concentration during evaporation, balancing salt concentrations and preventing localized oversaturation and crystallization of salt ions. Furthermore, the water film interacts weakly with salt ions. The dynamic water film barrier reduces the affinity of salt ions for the surface, making them more likely to dissolve in the water, thereby reducing the probability of salt crystal nucleation and mitigating salt deposition at the evaporation interface. This concept opens the possibility of realizing anti-fouling and salt-resistant hydrogel evaporators.

[0007] Based on the synergistic effect of multiple metals and the designability of components, the new high-entropy alloy system provides the possibility of realizing this concept through the strategy of constructing a multi-principal element equiatomic ratio solid solution. The face-centered cubic solid solution formed by five or more transition metal elements can achieve an average light absorption rate of over 92% in the wide spectral range of 300nm-2500nm by virtue of dd interband transitions and localized surface plasmon resonance effects. The introduction of the antibacterial element Cu can achieve the coupling of photothermal and antibacterial effects, and it constructs a dynamic antibacterial interface through the slow release of metal ions and the synergistic photothermal effect. If the bionic structure of the pitcher plant is combined with this, multiple resistance and prevention measures against marine fouling organisms can be achieved, breaking through the limitations of traditional single antifouling mechanisms in the face of complex marine environments. It may show unique advantages in fields such as seawater desalination and medical device surface sterilization that require high dynamic responsiveness, efficient energy conversion and low microbial contamination.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is as follows: The present invention provides a high-strength bionic hydrogel evaporator with salt resistance and anti-fouling functions. A bionic pitcher plant mold is constructed by observing and designing the structure of the rim of a real pitcher plant. The hydrogel evaporator achieves mechanical strength capable of replicating the bionic structure by regulating the molecular weight of the hydrogel components. The evaporator is a hydrogel composite material constructed from a high-entropy alloy nano-dispersion system. High-entropy alloy nanoparticles are homogenized and composited with hydrogel, and then in-situ cross-linked and cured to form a structure with a three-dimensional network distribution characteristic of a nano-reinforced phase. The cross-linking density and pore size of the hydrogel are changed by regulating the number of freeze-thaw cycles and the operation time, so as to obtain mechanical strength capable of resisting external forces and rapid water transmission capability.

[0009] The high-strength bionic hydrogel evaporator with salt resistance and anti-fouling functions of the present invention has a pitcher plant rim bionic structure on its surface and is composed of a hydrogel matrix and high-entropy alloy nanoparticles; High-entropy alloy nanoparticles have a solid solution structure and are uniformly dispersed in the hydrogel matrix. They are composed of Fe, Ni, Ti, Cr, Mn, and Cu metal elements in a six-element equiatomic ratio configuration (each metal element has an equal atomic percentage in the high-entropy alloy), achieving a synergistic effect of the components through a multi-principal element solid solution structure. The hydrogel matrix has a continuous phase structure, consisting of a polymer network skeleton formed by physical cross-linking and curing of polyvinyl alcohol (PVA); The hydrogel evaporator has the ability to resist salt crystallization and biological pollution (including protein, bacteria and algae) in seawater desalination applications.

[0010] The mass ratio of hydrogel matrix to high entropy alloy nanoparticles is 100:(5-20); The hydrogel matrix includes a low molecular weight hydrogel component and a high molecular weight hydrogel component, the mass ratio of the two is 100:(20-100), the molecular weight range of the two is 10000-100000, and the molecular weight of the high molecular weight hydrogel component is greater than that of the low molecular weight hydrogel component.

[0011] The method for preparing the high-strength bionic hydrogel evaporator with salt resistance and anti-fouling functions of the present invention comprises the following steps: Step 1: Prepare high-entropy alloy nanoparticles and a biomimetic mold with the topological features of the pitcher plant rim; Step 2: Functional component compounding and regulation: The hydrogel matrix material is dissolved in a binary co-solvent of water and an organic solvent. After complete dissolution through thermal activation treatment at a high temperature (50°C-80°C), the high-entropy alloy nanoparticles prepared in step 1 are introduced under magnetic stirring conditions. The nanophase is dispersed through the synergistic effect of mechanical shear dispersion and gradient temperature increase (90°C-120°C) activation. After uniform dispersion, a composite hydrogel precursor solution with multi-scale uniform dispersion characteristics is finally formed. Step 3: Flow control molding and low-temperature phase change crosslinking: The composite hydrogel precursor solution obtained in step 2 is precisely injected into the molding biomimetic mold cavity with the topological characteristics of the pitcher plant rim during the molten flow state through injection technology to achieve solution rheological property optimization and biomimetic structure replication; the liquid-carrying mold is quickly transferred to a low-temperature phase change induction environment to trigger the orderly assembly of molecular chains and crosslinking and curing process. After physical crosslinking and curing, phase separation is completed and demolding is performed to obtain a high-entropy alloy-hydrogel composite evaporator with a biomimetic microstructure; Step 4: Multi-level pore construction: The high-entropy alloy-hydrogel composite evaporator with a bionic microstructure is subjected to freeze-thaw cycles and thermodynamic phase change strengthening treatment. The composite evaporator is quickly frozen with liquid nitrogen and then immersed in deionized water to thaw at controlled temperature, completing a freeze-thaw cycle. The freeze-thaw cycles are repeated multiple times to induce the ice crystal template effect to produce multi-level pore reconstruction, forming a mechanically enhanced bionic hydrogel evaporator; thus, a high-strength bionic hydrogel evaporator with salt resistance and anti-fouling functions is obtained.

[0012] In step 1, the method for preparing high entropy alloy nanoparticles includes the following steps: Step 1-1: Multiphase mechanical alloying pretreatment; High-purity (≥99.9%) transition metal powders of Fe, Ni, Ti, Cr, Mn, Cu, etc. with a particle size of ≤50μm are used as raw materials. Through a high-energy mechanical alloying process, ball milling is carried out in a three-dimensional planetary grinding system to achieve nano-scale compounding and obtain composite powders. The composite powders are prepared into columnar precursors using a cold isostatic pressing preforming process. The specific parameters of ball milling are: ball-to-material ratio of 20:1, rotation speed of 400rpm-800rpm, ball milling time of 12h-36h, ethanol is used as the organic dispersion medium to construct a layered composite powder with a balanced atomic ratio; the cold isostatic pressing pressure is 300MPa.

[0013] Step 1-2: Plasma-assisted non-equilibrium synthesis; The precursor is placed in a non-consumable electrode arc melting system and an oxygen-free environment is established through three-stage vacuum degassing with an ultimate vacuum degree of ≤5×10 -3Pa; an H2 / Ar mixed gas with a volume ratio of 1:9 was introduced as an ionizing medium, and arc discharge treatment was performed for 5 min-30 min under the action of a pulse arc with a current of 500 A and a voltage of 30 V to obtain high-entropy alloy nanoparticles and achieve in-situ nano-reconstruction; Key control points include: using a liquid nitrogen-assisted cooling system to maintain the substrate temperature in the critical phase transition range of 7°C-10°C during arc discharge treatment, inhibiting grain coarsening through non-equilibrium phase transition; the product after 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.

[0014] In step 1, the method for preparing a bionic mold having the topological characteristics of the pitcher plant rim includes the following main contents: Based on the principles of biomimetic fabrication, the three-dimensional morphological features of the Nepenthes rim region were captured through freeze-drying combined with scanning electron microscopy. Three-dimensional modeling software was then used to reconstruct a biomimetic topological structure with overlapping micro-pits. Using resin as the raw material, the biomimetic structure was printed using photopolymerization additive manufacturing (SLM). Post-processing included ultrasonic cleaning with gradient solvents (isopropyl alcohol / ethanol) to remove any uncured resin residue, rapid drying with high-purity nitrogen, and secondary UV curing to enhance cross-linking stability. The resulting biomimetic mold exhibited the topological characteristics of the Nepenthes rim, resulting in a biomimetic Nepenthes micro-nanostructure with precise geometric features. By combining reverse engineering of biological prototypes with precision manufacturing techniques, the directional liquid film transport function of the Nepenthes rim region was successfully replicated.

[0015] 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 low molecular weight hydrogel component and the high molecular weight hydrogel component is 100:(20-100), and the molecular weight of the high molecular weight hydrogel component is in the range of 10,000-100,000; the molecular weight of the high molecular weight hydrogel component is greater than that of the low molecular weight hydrogel component; The composite hydrogel precursor solution is a bicontinuous phase solvent system, in which the mass ratio of the hydrogel matrix (a mixed system of polyvinyl alcohol with different molecular weights) and the high entropy alloy nanoparticles (Fe-Ni-Ti-Cr-Mn-Cu system) is 100:(5-20); The binary co-solvent is a co-solvent of water and dimethyl sulfoxide (DMSO). DMSO helps lower the freezing point of water and form a porous structure. The mass ratio of the organic solvent (DMSO) to deionized water is 100:(2-8). The mass ratio of the binary co-solvent medium to the hydrogel matrix is ​​100:(1-20); A gradient temperature ramp was implemented in a high-temperature constant-temperature circulating oil bath to prepare a composite hydrogel precursor solution: The first stage: under magnetic stirring, the temperature is raised to 50℃-80℃ and kept warm for 1h-5h to completely dissolve the hydrogel matrix in the binary co-solvent medium and activate the hydroxyl association of polyvinyl alcohol molecular chains with different molecular weights; the second stage: after introducing high-entropy alloy nanoparticles, the temperature is further raised to 90℃-120℃ and kept warm for 1h-5h to induce the high-entropy alloy nanoparticles to disperse and coordinate with polyvinyl alcohol, and the polyvinyl alcohol chains with different molecular weights to entangle with each other; the whole process is carried out under magnetic stirring to ensure the uniform dispersion of different phases; Step 2: A biomimetic demoulding system is constructed through a multi-stage molecular weight ratio control strategy. A gradient cross-linking network construction process is used to compound two hydrogel precursors of different molecular weights in sections according to proportion. Combined with the biomimetic topological structure fidelity control technology, the demoulding mechanical strength is optimized to ensure structural integrity and biomimetic microstructure replication accuracy. In step 3, physical crosslinking and curing is to perform physical crosslinking of polyvinyl alcohol in a low temperature environment of -20°C to 4°C, and to regulate the pore size distribution of the three-dimensional network through the ice crystal template effect. The crosslinking time is 8h-18h, and the crosslinking density and mechanical strength are balanced. In step 4, the freeze-thaw cycle is carried out in a segmented manner to obtain a porous and high-strength hydrogel evaporator, and step-by-step temperature control is implemented in the liquid nitrogen rapid cooling stage: first, a pre-cooling stage is carried out, freezing at -80°C for 1s-100s, and then a deep freezing stage is carried out, freezing at -196°C for 120s-240s, and after the deep freezing stage, temperature-controlled thawing is performed. The thawing process adopts a gradient heating 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 2-5 freeze-thaw cycles to form a pore gradient structure.

[0016] In step 4, the organic solvent in the biomimetic microstructured high entropy alloy-hydrogel composite evaporator is first replaced with deionized water to achieve solvent replacement purification, thereby obtaining a purified high entropy alloy-hydrogel composite evaporator, and then performing multi-stage pore construction; The substrate is treated by a dynamic osmotic equilibrium 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 20°C-30°C for 5 hours to 24 hours until the organic solvent is completely replaced by solvent phase migration under constant pressure, thereby completing the elution and replacement of the organic solvent and stabilizing the three-dimensional network structure. In step 4, surface activation and packaging are performed after the multi-level channel construction is completed; the specific operation is to place the bionic hydrogel evaporator after the multi-level channel construction is completed in a constant temperature ion balance environment of a 26°C deionized water system for activation, and form a stable protective interface through self-assembly of the bionic surface hydration layer, thereby obtaining a high-strength bionic hydrogel evaporator with salt resistance and anti-fouling functions.

[0017] This invention utilizes novel high-entropy alloy nanoparticles that combine efficient photothermal conversion with synergistic antibacterial properties, inspired by the biomimetic structure of the pitcher plant rim. By manipulating the mechanical strength of the hydrogel, a high-strength biomimetic hydrogel evaporator with salt and antifouling properties is constructed. The synergistic effect of the high-entropy alloy and the biomimetic structure enables the evaporator to absorb up to 98.5% of sunlight and kill over 99% of both Gram-positive and Gram-negative bacteria under illumination. Furthermore, the biomimetic structure provides excellent resistance to marine fouling at various stages and allows the evaporator to withstand extended periods of seawater without salt crystallization. This technological system, which deeply integrates biomimetic structural design, achieves a balanced control of high-strength and high-speed water transport, and utilizes multifunctional and stable high-entropy alloy nanoparticles, overcomes the technical bottlenecks of traditional evaporators in terms of photothermal efficiency and salt resistance, providing both theoretical and practical innovations for the development of intelligent water treatment systems for industrial applications.

[0018] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention replicates the bionic structure of the pitcher plant rim on the surface of a hydrogel evaporator, enabling the surface to rapidly transport water and form a water film. The presence of the flowing water film not only imparts super-hydrophilic properties to the evaporator, accelerating the water evaporation rate and giving the material surface a dynamic renewal capability, but also acts as a physical barrier, reducing microbial attachment and preventing the formation of marine biofouling. Simultaneously, the Marangoni effect is utilized to cause salt ions to undergo ion exchange behaviors such as convection and diffusion, thus preventing the formation of salt crystals.

[0019] 2. This invention utilizes high-entropy alloy nanoparticles, which have achieved a synergistic and stable integration of photothermal response characteristics and broad-spectrum antimicrobial properties, as a photothermal material, enabling them to be used as a means of killing bacteria and other microorganisms. The biomimetic structure's multiple light reflection and refraction micro-nano effects further enhance light absorption. The coupling of the biomimetic structure with the multifunctional high-entropy alloy achieves a synergistic antifouling effect across chemical, physical, and micro-nanostructural aspects, breaking through the efficiency bottleneck of traditional single-mode antifouling methods and providing an innovative, synergistic solution for microbial killing.

[0020] 3. The high-strength biomimetic hydrogel evaporator with salt and antifouling functions provided by the present invention has excellent mechanical properties. It can not only accurately replicate the biomimetic structure, but also resist external environmental forces to maintain its own structural changes. It has good stability to meet the application requirements under complex conditions. Through the coordinated regulation of its mechanical strength by molecular weight control and freeze-thaw cycles, the evaporator maintains the above-mentioned mechanical properties without affecting the water transmission effect, and the evaporation rate is further improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1The image of the high entropy alloy nanoparticles in Example 3 of the present invention is displayed with the assistance of scanning transmission electron microscopy (HAADF-STEM) and energy-dispersive X-ray spectroscopy (EDS); Figure 2 is an X-ray photoelectron spectroscopy (XPS) graph of the sample; HEA-PVA(S) is the high-strength bionic hydrogel evaporator with salt resistance and antifouling function in Example 3 of the present invention, and PVA is the high-strength hydrogel evaporator in Comparative Example 1; Figure 3 3 are images of a high-strength bionic hydrogel evaporator with salt resistance and anti-fouling functions in Example 3 of the present invention; (a) is a physical image of the bionic hydrogel evaporator, and (b) is a scanning electron microscope (SEM) image of the bionic hydrogel evaporator; Figure 4 is an absorption spectrum curve of the sample; HEA is the high entropy alloy nanoparticles in Example 3 of the present invention, HEA-PVA(S) is the high-strength bionic hydrogel evaporator with salt resistance and antifouling function 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; Figure 5 : is a water evaporation weight loss curve of the sample; HEA-PVA(S) is the high-strength bionic hydrogel evaporator with salt resistance and antifouling function in Example 3 of the present invention, 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; Figure 6 The figures are the anti-fluorescein-labeled bovine serum albumin (BSA-FITC) effect diagrams of the samples; (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 salt resistance and anti-fouling function in Example 3. The data marked in the figure are the fluorescence intensity of adsorbed fluorescein-labeled bovine serum albumin (BSA-FITC); 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; 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; Figure 9This 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; 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

[0022] 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.

[0023] 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.

[0024] Based on a cross-disciplinary technology integration strategy, the present invention achieves functional integration of a high-performance photothermal evaporator through the following innovative approaches: A three-dimensional interconnected porous composite hydrogel matrix (polyvinyl alcohol / high entropy alloy composite system) is used to construct a gradient pore structure, and a multi-stage freeze-thaw crosslinking process is used to control the pore size distribution and mechanical strength. The micro-nanostructure at the rim of the pitcher plant is innovatively combined with gradient surface energy control technology to form a directional flowing water film of a certain thickness at the evaporation interface, achieving salt crystallization resistance through the Marangoni effect. A specially designed surface engineering treatment imparts self-cleaning properties to the material, preventing biofouling during continuous operation. Finally, Fe-Ni-Ti-Cr-Mn-Cu high entropy alloy nanoparticles (HEA-NPs) are introduced into the photothermal conversion layer, leveraging the synergistic effects of dd orbital transitions and biomimetic structures to further enhance full-spectrum absorption. The synergistic use of micro-nanostructures and high-entropy alloys transcends the single-step approach of traditional marine antifouling methods, achieving multi-stage antifouling properties and significantly improving antifouling capabilities. This integrated solution uses bionic structure optimization and coordinated regulation of multiple physical fields to ultimately produce a high-strength bionic hydrogel evaporator with salt resistance and anti-fouling functions.

[0025] The high-strength biomimetic hydrogel evaporator, fabricated in this example and featuring salt-resistant and antifouling properties, features a pitcher plant rim biomimetic structure on its surface. The evaporator 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 within the hydrogel matrix. They consist of Fe, Ni, Ti, Cr, Mn, and Cu metal elements in a hexavalent equiatomic configuration. The hydrogel matrix has a continuous phase structure, composed of a polymer network backbone formed by physical crosslinking and curing of polyvinyl alcohol. The biomimetic mold measures approximately 2 cm × 2 cm × 0.5 cm, and the surface of the mold cavity features the pitcher plant rim micro-nanostructure.

[0026] The present invention is further described below in conjunction with specific embodiments and accompanying drawings:

[0027] Example 1

[0028] In the high-strength bionic hydrogel evaporator with salt resistance and anti-fouling 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 ​​10,000, and the molecular weight of the high molecular weight hydrogel component is 80,000, and the mass ratio of the two is 100:20.

[0029] The specific preparation method comprises the following steps: Step 1: Prepare high-entropy alloy nanoparticles and a bionic mold with the topological features of the pitcher plant rim.

[0030] The preparation method of high entropy alloy nanoparticles is as follows: Step 1-1: Multiphase mechanical alloying pretreatment.

[0031] High-purity (≥99.9%) transition metal elements (Fe / Ni / Ti / Cr / Mn / Cu, particle size ≤50μm) are used as raw materials. Through a high-energy mechanical alloying process, ball milling is carried out in a three-dimensional planetary grinding system to achieve nano-scale composite and obtain composite powder; the composite powder is prepared into a columnar precursor using a cold isostatic pressing preforming process.

[0032] The specific ball milling parameters were: a ball-to-powder ratio of 20:1, a rotation speed of 600 rpm, and a milling time of 12 hours. Ethanol was used as the organic dispersion medium to construct a layered composite powder with a well-balanced atomic ratio. Subsequently, a cold isostatic pressing process (pressure of 300 MPa) was used to prepare a columnar precursor.

[0033] Step 1-2: Plasma-assisted non-equilibrium synthesis.

[0034] The precursor is placed in a non-consumable electrode arc melting system and degassed by three-stage vacuum (limit vacuum ≤ 5×10 -3An oxygen-free environment was established at 100 Pa. An H2 / Ar gas mixture (volume ratio 1:9) was then introduced as an ionizing medium. A pulsed arc (current 500A, voltage 30V) was then applied for 10 minutes to produce high-entropy alloy nanoparticles, achieving in-situ nanostructural reconstruction.

[0035] Key control points include: using a liquid nitrogen-assisted cooling system to maintain the substrate temperature in the critical phase transition range (ΔT=7°C) during arc discharge treatment, inhibiting grain coarsening through non-equilibrium phase transition; the product after arc discharge treatment is exposed to air for 6 hours to form a passivation film on its surface, and high-entropy alloy nanoparticles with stable surface energy are obtained through oxide layer passivation.

[0036] The preparation method of the bionic mold with the topological characteristics of the pitcher plant rim is as follows: Based on biomimetic fabrication principles, the three-dimensional morphological features of the Nepenthes rim region were captured through freeze-drying combined with scanning electron microscopy. Three-dimensional modeling software was then used to reconstruct a biomimetic topological structure with overlapping micro-pits. Photocuring additive manufacturing (SLA) was used to print the biomimetic structure. Post-processing included ultrasonic cleaning with gradient solvents (isopropyl alcohol / ethanol) to remove any uncured resin residues, rapid drying with high-purity nitrogen, and secondary UV curing to enhance cross-linking stability. The resulting biomimetic mold exhibited the topological characteristics of the Nepenthes rim, resulting in a biomimetic Nepenthes micro-nanostructure with precise geometric features. By combining reverse engineering of biological prototypes with precision manufacturing techniques, the directional liquid film transport function of the Nepenthes rim region was successfully replicated.

[0037] Step 2: Functional component combination and regulation.

[0038] Two polyvinyl alcohol hydrogels with different molecular weights were selected, the low molecular weight polyvinyl alcohol hydrogel component had a molecular weight of 10,000, and the high molecular weight polyvinyl alcohol hydrogel component had a molecular weight of 80,000; the mass ratio of the low molecular weight hydrogel component to the high molecular weight hydrogel component was 100:20, and a mixed polyvinyl alcohol hydrogel component was obtained to meet the demolding requirements.

[0039] 0.3g of the mixed polyvinyl alcohol (PVA) hydrogel component was dissolved in a mixture of 0.2g of water and 5g of dimethyl sulfoxide (DMSO), a binary co-solvent. 0.03g of high-entropy alloy (HEA) nanoparticles were then added and dispersed evenly to form a composite hydrogel precursor solution. Due to mechanical performance requirements, a gradient temperature ramp was employed. In the first stage, the temperature was raised to 60°C and maintained for 1 hour to completely dissolve the PVA. In the second stage, after the HEA nanoparticles were introduced, the temperature was further raised to 90°C and maintained for 3 hours. This entire process was performed using a magnetic stirring system to ensure uniform dispersion of the different phases. The composite hydrogel precursor solution was obtained after the PVA and HEA formed a homogeneous phase.

[0040] Step 3: flow control molding and low-temperature phase change crosslinking.

[0041] The composite hydrogel precursor solution obtained in step 2 is precisely poured into a biomimetic mold cavity having the topological characteristics of the pitcher plant rim by injection technology when the composite hydrogel precursor solution is in a molten flow state; The liquid-carrying mold was quickly transferred to a low-temperature phase change induction environment of -20°C to trigger the orderly assembly and cross-linking curing process of the molecular chains, causing the polyvinyl alcohol hydrogel components to undergo physical cross-linking to form a solid gel. The low-temperature polymerization time was 10 hours. After the physical cross-linking curing was completed, the mold was removed to obtain a high-entropy alloy-hydrogel composite evaporator with a bionic microstructure.

[0042] Step 4: Multi-level channel construction.

[0043] First, solvent replacement purification is performed. The specific method is as follows: the substrate is treated by dynamic osmotic equilibrium method, and the high entropy alloy-hydrogel composite evaporator with a biomimetic microstructure obtained in step 3 is replaced by solvent phase migration under constant pressure conditions. It is immersed in deionized water at room temperature of 22°C for 8 hours until the organic solvent is completely replaced to obtain a purified high entropy alloy-hydrogel composite evaporator.

[0044] After purification, multi-stage pore construction was performed. The specific method was as follows: the purified high-entropy alloy-hydrogel composite evaporator was subjected to a freeze-thaw cycle, and step-by-step temperature control was implemented in the liquid nitrogen rapid cooling stage: first, a pre-cooling stage was performed: freezing at -80°C for 10 seconds, and then a deep freezing stage was performed: freezing at -196°C for 150 seconds. After the deep freezing stage, it was immersed in deionized water for temperature control and thawing. The gradient heating method was used to heat the temperature to 25°C at a rate of 5°C / min to complete a freeze-thaw cycle; the freeze-thaw cycle was repeated twice to complete the multi-stage pore reconstruction and obtain a mechanically enhanced high-entropy alloy-hydrogel composite evaporator.

[0045] After constructing the multi-level channels, surface activation and encapsulation are carried out. The specific method is as follows: the mechanically enhanced composite hydrogel evaporator is placed in a constant temperature ion balance environment (26°C deionized water system) for activation, and a stable protective interface is formed through the self-assembly of the bionic surface hydration layer to obtain a high-strength bionic hydrogel evaporator with salt resistance and anti-fouling functions.

[0046] Example 2 In the high-strength bionic hydrogel evaporator with salt resistance and anti-fouling 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 ​​15,000, and the molecular weight of the high molecular weight hydrogel component is 60,000, and the mass ratio of the two is 100:40.

[0047] The specific preparation method comprises the following steps: Step 1: Prepare high-entropy alloy nanoparticles and a bionic mold with the topological features of the pitcher plant rim.

[0048] The preparation method of high entropy alloy nanoparticles is as follows: Step 1-1: Multiphase mechanical alloying pretreatment.

[0049] High-purity (≥99.9%) transition metal elements (Fe / Ni / Ti / Cr / Mn / Cu, particle size ≤50μm) are used as raw materials. Through a high-energy mechanical alloying process, ball milling is carried out in a three-dimensional planetary grinding system to achieve nano-scale composite and obtain composite powder; the composite powder is prepared into a columnar precursor using a cold isostatic pressing preforming process.

[0050] The specific ball milling parameters were: a ball-to-powder ratio of 20:1, a rotation speed of 800 rpm, and a milling time of 15 hours. Ethanol was used as the organic dispersion medium to construct a layered composite powder with a well-balanced atomic ratio. A columnar precursor was then prepared using a cold isostatic pressing process (pressure of 300 MPa).

[0051] Step 1-2: Plasma-assisted non-equilibrium synthesis.

[0052] The precursor is placed in a non-consumable electrode arc melting system and degassed by three-stage vacuum (limit vacuum ≤ 5×10 -3 An oxygen-free environment was established at 150 Pa. An H2 / Ar gas mixture (volume ratio 1:9) was introduced as an ionizing medium. Arc discharge treatment was performed for 20 minutes under a pulsed arc (current 500 A, voltage 30 V) to obtain high-entropy alloy nanoparticles, achieving in-situ nanostructuring.

[0053] Key control points include: using a liquid nitrogen-assisted cooling system to maintain the substrate temperature in the critical phase transition range (ΔT=8°C) during arc discharge treatment, inhibiting grain coarsening through non-equilibrium phase transition; the product after arc discharge treatment is exposed to air for 8 hours to form a passivation film on its surface, and high-entropy alloy nanoparticles with stable surface energy are obtained through oxide layer passivation.

[0054] The preparation method of the bionic mold with the topological characteristics of the pitcher plant rim is as follows: Based on biomimetic fabrication principles, the three-dimensional morphological features of the Nepenthes rim region were captured through freeze-drying combined with scanning electron microscopy. Three-dimensional modeling software was then used to reconstruct a biomimetic topological structure with overlapping micro-pits. Photocuring additive manufacturing (SLA) was used to print the biomimetic structure. Post-processing included ultrasonic cleaning with gradient solvents (isopropyl alcohol / ethanol) to remove any uncured resin residues, rapid drying with high-purity nitrogen, and secondary UV curing to enhance cross-linking stability. The resulting biomimetic mold exhibited the topological characteristics of the Nepenthes rim, resulting in a biomimetic Nepenthes micro-nanostructure with precise geometric features. By combining reverse engineering of biological prototypes with precision manufacturing techniques, the directional liquid film transport function of the Nepenthes rim region was successfully replicated.

[0055] Step 2: Functional component combination and regulation.

[0056] Two polyvinyl alcohol hydrogels with different molecular weights were selected, the low molecular weight polyvinyl alcohol hydrogel component had a molecular weight of 15,000, and the high molecular weight polyvinyl alcohol hydrogel component had a molecular weight of 60,000; the mass ratio of the low molecular weight hydrogel component to the high molecular weight hydrogel component was 100:40, and a mixed polyvinyl alcohol hydrogel component was obtained to meet the demolding requirements.

[0057] 0.5g of the mixed polyvinyl alcohol (PVA) hydrogel component was dissolved in a mixture of 0.5g of water and 10g of dimethyl sulfoxide (DMSO), a binary co-solvent. 0.04g of high-entropy alloy (HEA) nanoparticles were then added and dispersed evenly to form a composite hydrogel precursor solution. Due to mechanical performance requirements, a gradient temperature ramp was employed. In the first stage, the temperature was raised to 50°C and maintained for 2 hours to completely dissolve the PVA. In the second stage, after the HEA nanoparticles were introduced, the temperature was further raised to 95°C and maintained for 1 hour. This entire process was performed using a magnetic stirring system to ensure uniform dispersion of the different phases. The composite hydrogel precursor solution was obtained after the PVA and HEA formed a homogeneous phase.

[0058] Step 3: flow control molding and low-temperature phase change crosslinking.

[0059] The composite hydrogel precursor solution obtained in step 2 is precisely poured into a molding mold cavity having the topological characteristics of the pitcher plant rim by injection technology when the composite hydrogel precursor solution is in a molten flow state; The liquid-carrying mold was quickly transferred to a low-temperature phase change induction environment of -10°C to trigger the orderly assembly and cross-linking curing process of the molecular chains, causing the polyvinyl alcohol hydrogel components to undergo physical cross-linking to form a solid gel. The low-temperature polymerization time was 10 hours. After the physical cross-linking curing was completed, the mold was demolded to obtain a high-entropy alloy-hydrogel composite evaporator with a bionic microstructure.

[0060] Step 4: Multi-level channel construction.

[0061] First, solvent replacement purification is performed. The specific method is as follows: the substrate is treated by dynamic osmotic equilibrium method, and the high entropy alloy-hydrogel composite evaporator with a biomimetic microstructure obtained in step 3 is replaced by solvent phase migration under constant pressure conditions. It is immersed in deionized water at room temperature of 25°C for 24 hours until the organic solvent is completely replaced to obtain a purified high entropy alloy-hydrogel composite evaporator.

[0062] After purification, multi-stage pore construction was performed. The specific method was as follows: the purified high-entropy alloy-hydrogel composite evaporator was subjected to a freeze-thaw cycle, and step-by-step temperature control was implemented in the liquid nitrogen rapid cooling stage: first, a pre-cooling stage was performed: freezing at -80°C for 50 seconds, and then a deep freezing stage was performed: freezing at -196°C for 210 seconds. After the deep freezing stage, it was immersed in deionized water for temperature control and thawing. The gradient heating method was used to heat the temperature to 25°C at a rate of 10°C / min to complete a freeze-thaw cycle; the freeze-thaw cycle was repeated 4 times to complete the multi-stage pore reconstruction and obtain a mechanically enhanced high-entropy alloy-hydrogel composite evaporator.

[0063] After constructing the multi-level channels, surface activation and encapsulation are carried out. The specific method is as follows: the mechanically enhanced composite hydrogel evaporator is placed in a constant temperature ion balance environment (26°C deionized water system) for activation, and a stable protective interface is formed through the self-assembly of the bionic surface hydration layer to obtain a high-strength bionic hydrogel evaporator with salt resistance and anti-fouling functions.

[0064] Example 3 In the high-strength bionic hydrogel evaporator with salt resistance and anti-fouling functions prepared in this embodiment, 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 ​​25,000, and the molecular weight of the high molecular weight hydrogel component is 50,000, and the mass ratio of the two is 100:50.

[0065] The specific preparation method comprises the following steps: Step 1: Prepare high-entropy alloy nanoparticles and a bionic mold with the topological features of the pitcher plant rim.

[0066] The preparation method of high entropy alloy nanoparticles is as follows: Step 1-1: Multiphase mechanical alloying pretreatment.

[0067] High-purity (≥99.9%) transition metal elements (Fe / Ni / Ti / Cr / Mn / Cu, particle size ≤50μm) are used as raw materials. Through a high-energy mechanical alloying process, ball milling is carried out in a three-dimensional planetary grinding system to achieve nano-scale composite and obtain composite powder; the composite powder is prepared into a columnar precursor using a cold isostatic pressing preforming process.

[0068] The specific ball milling parameters were: a ball-to-powder ratio of 20:1, a rotation speed of 750 rpm, and a milling time of 24 hours. Ethanol was used as the organic dispersion medium to construct a layered composite powder with a well-balanced atomic ratio. A columnar precursor was then prepared using a cold isostatic pressing process (pressure of 300 MPa).

[0069] Step 1-2: Plasma-assisted non-equilibrium synthesis.

[0070] The precursor is placed in a non-consumable electrode arc melting system and degassed by three-stage vacuum (limit vacuum ≤ 5×10 -3 An oxygen-free environment was established at 100 Pa. An H2 / Ar gas mixture (volume ratio 1:9) was then introduced as an ionizing medium. Arc discharge treatment was performed for 25 minutes under a pulsed arc (current 500 A, voltage 30 V) to obtain high-entropy alloy nanoparticles, achieving in-situ nanostructuring.

[0071] Key control points include: using a liquid nitrogen-assisted cooling system to maintain the substrate temperature in the critical phase transition range (ΔT=9°C) during arc discharge treatment, inhibiting grain coarsening through non-equilibrium phase transition; the product after arc discharge treatment is exposed to air for 10 hours to form a passivation film on its surface, and high-entropy alloy nanoparticles with stable surface energy are obtained through oxide layer passivation.

[0072] The preparation method of the bionic mold with the topological characteristics of the pitcher plant rim is as follows: Based on biomimetic fabrication principles, the three-dimensional morphological features of the Nepenthes rim region were captured through freeze-drying combined with scanning electron microscopy. Three-dimensional modeling software was then used to reconstruct a biomimetic topological structure with overlapping micro-pits. Photocuring additive manufacturing (SLA) was used to print the biomimetic structure. Post-processing included ultrasonic cleaning with gradient solvents (isopropyl alcohol / ethanol) to remove any uncured resin residues, rapid drying with high-purity nitrogen, and secondary UV curing to enhance cross-linking stability. The resulting biomimetic mold exhibited the topological characteristics of the Nepenthes rim, resulting in a biomimetic Nepenthes micro-nanostructure with precise geometric features. By combining reverse engineering of biological prototypes with precision manufacturing techniques, the directional liquid film transport function of the Nepenthes rim region was successfully replicated.

[0073] Step 2: Functional component combination and regulation.

[0074] Two polyvinyl alcohol hydrogels with different molecular weights were selected, the molecular weight of the low molecular weight polyvinyl alcohol hydrogel component was 25,000, and the molecular weight of the high molecular weight polyvinyl alcohol hydrogel component was 50,000; 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.

[0075] 2g of the mixed polyvinyl alcohol (PVA) hydrogel component was dissolved in a mixture of 0.25g of water and 10g of dimethyl sulfoxide (DMSO), a binary co-solvent. 0.1g of high-entropy alloy (HEA) nanoparticles was then added and dispersed evenly to form a composite hydrogel precursor solution. Due to mechanical performance requirements, a gradient temperature ramp was employed. In the first stage, the temperature was raised to 80°C and held for 1 hour to completely dissolve the PVA. In the second stage, after the HEA nanoparticles were introduced, the temperature was further raised to 100°C and held for 5 hours. This entire process was performed using a magnetic stirring system to ensure uniform dispersion of the different phases. The composite hydrogel precursor solution was obtained after the PVA and HEA formed a homogeneous phase.

[0076] Step 3: flow control molding and low-temperature phase change crosslinking.

[0077] The composite hydrogel precursor solution obtained in step 2 is precisely poured into a molding mold cavity having the topological characteristics of the pitcher plant rim by injection technology when the composite hydrogel precursor solution is in a molten flow state; The liquid-carrying mold was quickly transferred to a low-temperature phase change induction environment of -5°C to trigger the orderly assembly and cross-linking curing process of the molecular chains, causing the polyvinyl alcohol hydrogel components to undergo physical cross-linking to form a solid gel. The low-temperature polymerization time was 15 hours. After the physical cross-linking curing was completed, the mold was demolded to obtain a high-entropy alloy-hydrogel composite evaporator with a bionic microstructure.

[0078] Step 4: Multi-level channel construction.

[0079] First, solvent replacement purification is performed. The specific method is as follows: the substrate is treated by dynamic osmotic equilibrium method, and the high entropy alloy-hydrogel composite evaporator with a biomimetic microstructure obtained in step 3 is replaced by solvent phase migration under constant pressure conditions. It is immersed in deionized water at room temperature of 24°C for 15 hours until the organic solvent is completely replaced to obtain a purified high entropy alloy-hydrogel composite evaporator.

[0080] After purification, multi-stage pore construction was performed. The specific method was as follows: the purified high-entropy alloy-hydrogel composite evaporator was subjected to a freeze-thaw cycle, and step-by-step temperature control was implemented in the liquid nitrogen rapid cooling stage: first, a pre-cooling stage was performed: freezing at -80°C for 90 seconds, and then a deep freezing stage was performed: freezing at -196°C for 140 seconds. After the deep freezing stage, it was immersed in deionized water for temperature control and thawing. The gradient heating method was used to heat the temperature to 25°C at a rate of 15°C / min to complete a freeze-thaw cycle; the freeze-thaw cycle was repeated three times to complete the multi-stage pore reconstruction and obtain a mechanically enhanced high-entropy alloy-hydrogel composite evaporator.

[0081] After constructing the multi-level channels, surface activation and encapsulation are carried out. The specific method is as follows: the mechanically enhanced composite hydrogel evaporator is placed in a constant temperature ion balance environment (26°C deionized water system) for activation, and a stable protective interface is formed through the self-assembly of the bionic surface hydration layer to obtain a high-strength bionic hydrogel evaporator with salt resistance and anti-fouling functions.

[0082] Comparative Example 1 The high-strength hydrogel evaporator prepared in this comparative example does not contain high-entropy alloy nanoparticles and does not have a pitcher plant bionic structure on the surface. The molecular weight of the low molecular weight hydrogel component in the hydrogel matrix is ​​25,000, and the molecular weight of the high molecular weight hydrogel component is 50,000, and the mass ratio of the two is 100:50.

[0083] The specific preparation method comprises the following steps: Step 1: No high entropy alloy nanoparticles and bionic molds are prepared.

[0084] Step 2: Functional component combination and regulation.

[0085] Two polyvinyl alcohol hydrogels with different molecular weights were selected, the low molecular weight polyvinyl alcohol hydrogel component had a molecular weight of 25,000, and the high molecular weight polyvinyl alcohol hydrogel component had a molecular weight of 50,000; 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.

[0086] 2g of the mixed polyvinyl alcohol (PVA) hydrogel components were dissolved in a mixture of 0.25g of water and 10g of dimethyl sulfoxide (DMSO), a binary co-solvent. After uniform dispersion, a composite hydrogel precursor solution was formed. Due to mechanical performance requirements, a gradient temperature ramp was employed. In the first stage, the temperature was raised to 80°C and held for 1 hour to completely dissolve the PVA. In the second stage, the temperature was further raised to 100°C and held for 5 hours. This process was performed using a magnetic stirring system to ensure uniform dispersion of the different phases. The composite hydrogel precursor solution was obtained after the PVA components of different molecular weights formed a homogeneous phase.

[0087] Step 3: flow control molding and low-temperature phase change crosslinking.

[0088] The composite hydrogel precursor solution was injected into a common polytetrafluoroethylene mold cavity by injection technology when it was in a molten flow state. The mold was in the shape of a cuboid with a size of 2 cm × 2 cm × 0.5 cm. The liquid-carrying mold was quickly transferred to a low-temperature phase change induction environment of -5°C to trigger the orderly assembly and cross-linking curing process of the molecular chains, causing the polyvinyl alcohol hydrogel components to undergo physical cross-linking to form a solid gel. The low-temperature polymerization time was 15 hours. After the physical cross-linking curing was completed, the mold was demolded to obtain a hydrogel evaporator.

[0089] Step 4: Multi-level channel construction.

[0090] First, solvent replacement purification is performed. The specific method is as follows: the substrate is treated by dynamic osmotic equilibrium method, and the solvent phase migration replacement is performed under constant pressure conditions. The hydrogel evaporator obtained in step 3 is immersed in deionized water at room temperature of 24°C for 15 hours until the organic solvent is completely replaced, thereby obtaining a purified hydrogel composite evaporator.

[0091] After purification, multi-stage pore construction was performed. The specific method was as follows: the purified hydrogel composite evaporator was subjected to a freeze-thaw cycle, and step-by-step temperature control was implemented in the liquid nitrogen rapid cooling stage: first, a pre-cooling stage was performed: freezing at -80°C for 90 seconds, and then a deep freezing stage was performed: freezing at -196°C for 140 seconds. After the deep freezing stage, it was immersed in deionized water for temperature control and thawing. The gradient heating method was used to heat the temperature to 25°C at a rate of 15°C / min to complete a freeze-thaw cycle; the freeze-thaw cycle was repeated three times to obtain a high-strength hydrogel evaporator.

[0092] Comparative Example 2 The surface of the high-intensity light-heated hydrogel evaporator prepared in this comparative example does not have a pitcher plant bionic structure. 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 ​​25,000, and the molecular weight of the high molecular weight hydrogel component is 50,000. The mass ratio of the two is 100:50.

[0093] The specific preparation method comprises the following steps: Step 1: Preparation of high entropy alloy nanoparticles.

[0094] Step 1-1: Multiphase mechanical alloying pretreatment.

[0095] High-purity (≥99.9%) transition metal elements (Fe / Ni / Ti / Cr / Mn / Cu, particle size ≤50μm) are used as raw materials. Through a high-energy mechanical alloying process, ball milling is carried out in a three-dimensional planetary grinding system to achieve nano-scale composite and obtain composite powder; the composite powder is prepared into a columnar precursor using a cold isostatic pressing preforming process.

[0096] The specific ball milling parameters were: a ball-to-powder ratio of 20:1, a rotation speed of 750 rpm, and a milling time of 24 hours. Ethanol was used as the organic dispersion medium to construct a layered composite powder with a well-balanced atomic ratio. A columnar precursor was then prepared using a cold isostatic pressing process (pressure of 300 MPa).

[0097] Step 1-2: Plasma-assisted non-equilibrium synthesis.

[0098] The precursor is placed in a non-consumable electrode arc melting system and degassed by three-stage vacuum (limit vacuum ≤ 5×10 -3An oxygen-free environment was established at 100 Pa. An H2 / Ar gas mixture (volume ratio 1:9) was then introduced as an ionizing medium. Arc discharge treatment was performed for 25 minutes under a pulsed arc (current 500 A, voltage 30 V) to obtain high-entropy alloy nanoparticles, achieving in-situ nanostructuring.

[0099] Key control points include: using a liquid nitrogen-assisted cooling system to maintain the substrate temperature in the critical phase transition range (ΔT=9°C) during arc discharge treatment, inhibiting grain coarsening through non-equilibrium phase transition; the product after arc discharge treatment is exposed to air for 10 hours to form a passivation film on its surface, and high-entropy alloy nanoparticles with stable surface energy are obtained through oxide layer passivation.

[0100] Step 2: Functional component combination and regulation.

[0101] Two polyvinyl alcohol hydrogels with different molecular weights were selected, the low molecular weight polyvinyl alcohol hydrogel component had a molecular weight of 25,000, and the high molecular weight polyvinyl alcohol hydrogel component had a molecular weight of 50,000; 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.

[0102] 2g of the mixed polyvinyl alcohol (PVA) hydrogel component was dissolved in a mixture of 0.25g of water and 10g of dimethyl sulfoxide (DMSO), a binary co-solvent. 0.1g of high-entropy alloy nanoparticles was then added and dispersed evenly to form a composite hydrogel precursor solution. Due to mechanical performance requirements, a gradient temperature ramp was employed: the first stage was to raise the temperature to 80°C and hold for 1 hour, followed by a second stage of further heating to 100°C and holding for 5 hours. This entire process was performed using a magnetic stirring system to ensure uniform dispersion of the different phases. The composite hydrogel precursor solution was obtained after the PVA and high-entropy alloy formed a homogeneous phase.

[0103] Step 3: Flow control molding and low-temperature phase change crosslinking: The composite hydrogel precursor solution obtained in step 2 is injected into a conventional polytetrafluoroethylene mold cavity in a 2cm×2cm×0.5cm rectangular shape while in a molten flow state. The liquid-carrying mold was quickly transferred to a low-temperature phase change induction environment of -5°C to trigger the orderly assembly and cross-linking curing process of the molecular chains, causing the polyvinyl alcohol hydrogel components to undergo physical cross-linking to form a solid gel. The low-temperature polymerization time was 15 hours. After the physical cross-linking curing was completed, the mold was demolded to obtain a high-entropy alloy-hydrogel composite evaporator.

[0104] Step 4: Multi-level channel construction.

[0105] First, solvent replacement purification is performed. The specific method is as follows: the substrate is treated by dynamic osmotic equilibrium method, and the high entropy alloy-hydrogel composite evaporator obtained in step 3 is immersed in deionized water at room temperature of 24°C for 15 hours until the organic solvent is completely replaced by solvent phase migration under constant pressure conditions to obtain a purified high entropy alloy-hydrogel composite evaporator.

[0106] After purification, multi-stage channel construction was carried out. The specific method is as follows: the purified high-entropy alloy-hydrogel composite evaporator was subjected to a freeze-thaw cycle, and step-by-step temperature control was implemented in the liquid nitrogen rapid cooling stage: first, a pre-cooling stage treatment was performed: freezing at -80°C for 90 seconds, and then a deep freezing stage treatment was performed: freezing at -196°C for 140 seconds. After the deep freezing stage treatment, it was immersed in deionized water for temperature control and thawing. The gradient heating method was used to heat the temperature to 25°C at a rate of 15°C / min to complete a freeze-thaw cycle; the freeze-thaw cycle was repeated 3 times to obtain a high-intensity photothermal water gel evaporator.

[0107] Performance Analysis: 1. Morphology analysis of high entropy alloy nanoparticles: According to the results of scanning transmission electron microscopy (HAADF-STEM) and energy spectrum element distribution characterization (EDS), the multi-component high entropy alloy nanoparticles synthesized by the arc melting method in the present invention have a geometrically regular near-spherical morphology, a uniform particle size distribution and a smooth surface. Figure 1 Atomic-scale element distribution analysis shows that the metal components in the nanoparticles are in a disordered solid solution state in three-dimensional space, and no element segregation or phase separation is observed.

[0108] 2. XPS spectrum analysis: Figure 2 It can be seen that the high-strength bionic hydrogel evaporator with salt resistance and anti-fouling functions in Example 3 successfully composites high-entropy alloy nanoparticles.

[0109] 3. SEM image analysis: Figure 3 (a) Physical picture and Figure 3 From the morphology of the SEM image (b), it can be seen that the surface of the high-strength bionic hydrogel evaporator with salt resistance and anti-fouling functions in Example 3 presents a structure with multiple rows of overlapping micro-pits, which is consistent with the biological array arrangement characteristics at the edge of the pitcher plant, indicating that the high-strength bionic hydrogel evaporator with salt resistance and anti-fouling functions in Example 3 of the present invention successfully replicates the bionic structure of the pitcher plant.

[0110] 4. Solar Absorption Spectrum Analysis: A UV-Visible-Near-Infrared spectrophotometer (UV-3600i) equipped with an integrating sphere accessory was used to measure the sample's absorbance in the 300nm-2500nm band. After the instrument was preheated and stabilized, a baseline correction was performed using a barium sulfate pellet as a reference. The sample to be tested was evenly loaded and pelletized, then placed in the sample cell. Scan parameters were set: wavelength range 300nm-2500nm, slit width 20nm, data point interval 1nm, and reflectance (R) measurement mode. Upon initiating the scan, the instrument automatically activated the deuterium lamp in the UV region and the halogen tungsten lamp in the visible-near-infrared region as the light source. The detector collected the sample's reflected light signal in real time and converted it into absorbance data for output.

[0111] according to Figure 4 Solar absorption spectrum analysis shows that the high-strength bionic hydrogel evaporator with salt resistance and anti-fouling functions in Example 3 of the present invention successfully composites high-entropy alloy nanoparticles, combining high-entropy alloy nanoparticles with the bionic pitcher plant rim structure, and exhibits significant optical performance optimization: the high-entropy alloy synergistically achieves enhanced light absorption in a wide spectral range of 300nm-2500nm through the dd interband transition mechanism of 3d transition metals; at the same time, the micro-nanostructure designed on the surface of the bionic pitcher plant reduces the solar reflectivity through multiple light scattering effects, forming a coupling effect with the light absorption characteristics of the high-entropy alloy nanoparticles, ultimately achieving an ultra-high solar light absorption rate of 98.5%.

[0112] 5. Water Evaporation Mass Loss Curve Analysis: Distilled water evaporation rate testing was performed using a xenon lamp light source (simulating single-sun irradiance of AM 1.5G) and a precision analytical balance with an accuracy of 0.0001g. After the sample stabilized in a constant temperature environment, the initial mass was recorded. The light source was turned on to ensure uniform heating of the sample surface, and the sample was placed on a precision balance. The balance automatically outputs real-time mass data every minute. The continuously recorded time-mass curve was used to calculate the mass loss of deionized water per unit time. This, combined with the sample surface area, yielded the water evaporation rate.

[0113] Figure 5 The absolute value of the slope of each curve represents the water evaporation rate. The evaporation rate of Example 3 is 2.85 kg·m -2 ·h -1 The high-strength bionic hydrogel evaporator with salt resistance and anti-fouling function in Example 3 shows excellent water evaporation performance: high-entropy alloy nanoparticles achieve improved photothermal conversion efficiency in a wide spectral range through the synergistic interband transition effect of 3d transition metals, making the evaporation rate higher than that of the high-strength hydrogel evaporator in Comparative Example 1 (2.0 kg·m -2 ·h -1) increased by 42.5%; and the micro-nano structure designed by bionic pitcher plants on the surface suppressed reflection through multiple light scattering and formed a continuous directional water film, further increasing the evaporation rate compared with the high-intensity light-heated water gel evaporator in comparative example 2 (2.4 kg·m -2 ·h -1 ) increased by 18.8%. This performance improvement is due to a dual material-structure synergy: the high-entropy alloy-enhanced localized surface plasmon resonance effect and the biomimetic microstructure-induced rapid water supply-evaporation dynamic balance, which together overcome the light absorption and mass transfer limitations of traditional evaporators.

[0114] 6. Antifouling Performance Analysis: Evaluation of the material's surface biofouling resistance: All samples were pre-sterilized with UV light for 30 minutes. Antiprotein Adsorption Assay: Samples were incubated with a 1 mg / mL BSA / FITC solution for 24 hours, then rinsed with PBS and vortexed, and observed using a CLSM (Ex / Em = 493 / 550 nm). Antibacterial Assay: In the absence of light, samples were immersed in a diluted bacterial solution of Pseudomonas aeruginosa or Bacillus vietnamese (37°C, 7 days), then rinsed with PBS, and antibacterial activity was quantified by plate count. Antialgae Assay: Samples were immersed in a diluted algae solution of Chlorella vulgaris or Trigonella triangularis (22°C, 3000 Lux, 7 days), then rinsed with PBS, and the adhesion of fouling organisms to the material surface was observed using a CLSM (Ex / Em = 493 / 550 nm).

[0115] Depend on Figure 6 (a) Figure 6 (b) and Figure 6 (c) It can be seen that the high-strength bionic hydrogel evaporator prepared by the present invention can resist bovine serum albumin to a certain extent; Figure 7 (a) Figure 7 (b) Figure 7 (c) and Figure 7 (d) It can be seen that the high-strength bionic hydrogel evaporator can resist Pseudomonas aeruginosa and has a certain bactericidal effect, especially under light conditions; Figure 8 (a) Figure 8 (b) and Figure 8 (c) It can be seen that this high-strength biomimetic hydrogel evaporator is able to resist the adhesion of microorganisms such as Chlorella vulgaris. This indicates that the high-strength biomimetic hydrogel evaporator, with its Nepenthes biomimetic surface, further enhances its antifouling capabilities due to the construction of a super-hydrophilic surface and the presence of a flowing water film. When the high-strength biomimetic hydrogel evaporator with salt resistance and antifouling capabilities from Example 3 was exposed to sunlight at one solar intensity (other conditions were the same as those for the sample antibacterial test), the antibacterial rate was further increased to over 99% due to the synergistic bactericidal effect of the high-entropy alloy.

[0116] 7. Salt Resistance Analysis: The evaporation rate of brine was tested using a xenon lamp light source (simulating single-sun irradiance of AM 1.5G) and a precision analytical balance with an accuracy of 0.0001g. After the sample stabilized in a constant temperature environment, the initial mass was recorded. The light source was turned on to ensure uniform heating of the sample surface, and the sample was placed on a precision balance. The balance automatically outputs real-time mass data every minute. The mass loss of the simulated brine (3.5 wt.% NaCl solution) per unit time was calculated from the continuously recorded time-mass curve. The evaporation rate was then calculated based on the sample surface area. Optical photographs of the sample surface were taken after 1, 5, 10, 15, and 20 evaporation cycles to represent the salt crystallization process.

[0117] Depend on Figure 9 The analysis showed that as the number of salt water evaporation cycles increased, no salt crystals appeared on the sample surface, the pitcher plant biomimetic structure remained intact, and the water evaporation rate of the high-strength biomimetic hydrogel evaporator with salt resistance and anti-fouling function in Example 3 was basically constant at 2.45 kg·m -2 ·h -1 , with good durability and salt resistance.

[0118] 8. Mechanical Properties Analysis: Dumbbell-shaped specimens (National Standard Type II) were prepared using the hydrogel matrix and high-entropy alloy ratios described in Example 3 and the hydrogel ratio described in Comparative Example 1. Uniaxial tension was applied at a rate of 10 mm / min until fracture, with stress-strain curves simultaneously recording fracture strength and elongation. Cylindrical specimens (Φ20 × 20 mm) were also prepared using the hydrogel matrix and high-entropy alloy ratios described in Example 3. Compressive stress-strain curves were obtained using the same testing environment. The fixtures were treated with anti-slip treatment, and silicone oil was applied to the compression interface to reduce friction. ≥5 specimens were tested in parallel per group, and outliers were removed.

[0119] Depend on Figure 10 (a) The tensile stress-strain curve shows that compared with the hydrogel evaporator in comparative example 1, the tensile strength of the hydrogel evaporator in Example 3 with the introduction of high entropy alloy nanoparticles is increased by about 60%, and the mechanical strength is greatly improved; Figure 10 (b) Analysis of the compressive stress-strain curve shows that the highest compressive strength of the high-strength bionic hydrogel evaporator with salt resistance and anti-fouling functions in Example 3 of the present invention reaches over 1 MPa, which is a high-strength hydrogel in the field of hydrogel evaporators and can withstand external environmental forces while maintaining its own 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; 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 bionic hydrogel evaporator with salt resistance and anti-fouling function according to claim 1, characterized in that: 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 weight range of the high molecular weight hydrogel component and the low molecular weight hydrogel component are both 10,000-100,000.

3. The method for preparing the bionic hydrogel evaporator with salt resistance and antifouling function according to claim 1 or 2, 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.

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: 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.

5. The method for preparing a bionic hydrogel evaporator with salt resistance and antifouling function according to claim 4, 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.

6. The method for preparing a bionic hydrogel evaporator with salt resistance and antifouling function according to claim 3, 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).

7. The method for preparing a bionic hydrogel evaporator with salt resistance and antifouling function according to claim 3, 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 uniform dispersion.

8. The method for preparing a bionic hydrogel evaporator with salt resistance and antifouling function according to claim 3, 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.

9. The method for preparing a bionic hydrogel evaporator with salt resistance and antifouling function according to claim 3, 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.

10. The method for preparing a bionic hydrogel evaporator with salt resistance and antifouling function according to claim 3, 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