A rapid water transport superspreading hydrogel material and its preparation method

Abstract

This invention discloses a rapid water transport superspreading hydrogel material and its preparation method. The method includes loading a surfactant onto porous or hollow micro / nanoparticles using negative pressure rotary evaporation technology; in-situ growing and modifying a hydrophobic silica nanoparticle shell on the surface of the porous or hollow particles to form photothermal conversion superhydrophilic core-shell particles; subsequently, mixing the photothermal conversion superhydrophilic core-shell particles, hydrogel monomers, initiators, crosslinking agents, and co-crosslinking agents in a certain proportion under low-temperature conditions; and obtaining a rapid water transport superspreading hydrogel precursor after uniform dispersion; finally, obtaining the rapid water transport superspreading hydrogel material through directional freezing or chemical crosslinking. This invention, by doping the hydrogel with photothermal conversion superhydrophilic core-shell particles, on the one hand, endows the hydrogel with superspreading properties, significantly improving the water contact angle and spreading speed, enabling rapid seawater transport in solar-driven interfacial evaporation; on the other hand, the combination of porous or hollow micro / nanoparticle loading and the encapsulation effect of the hydrophobic silica shell significantly slows down surfactant loss, thereby extending the service life of the superspreading hydrogel.

Description

Technical Field

[0001] This invention relates to the field of new energy power electronic conversion technology, and in particular to a fast water transport superspreading hydrogel material and its preparation method. Background Technology

[0002] With the increasing scarcity of global freshwater resources, solar-driven interfacial evaporation technology has become a research hotspot in the fields of seawater desalination and wastewater treatment due to its advantages such as being green, sustainable, and energy-free. The core of this technology lies in the interfacial evaporator, which achieves rapid localized heating and seawater evaporation by placing photothermal materials at the water-air interface. However, current research on interfacial evaporators generally focuses on photothermal conversion efficiency and thermal management performance, neglecting the limitation of the evaporation rate on the rate of seawater transport to the evaporator interface.

[0003] To address this issue, advanced technologies commonly employ hydrophilic modification to enhance the wettability of seawater in interfacial evaporators. This includes grafting hydrophilic groups, applying hydrophilic coatings, and encapsulating hydrogels. Hydrogels, with their three-dimensional network structure, unique enthalpy regulation capabilities, and excellent hydrophilicity, are widely considered ideal materials for hydrophilic modification of interfacial evaporators. However, conventional hydrogels have a water contact angle greater than 10°, exhibiting only hydrophilicity, and their water spreading speed is relatively slow, thus limiting their ability to improve seawater transport speed. This insufficient surface hydrophilicity and water spreading speed leads to a reduction in the actual evaporation area and inadequate seawater supply, decreasing evaporation rate and efficiency. Furthermore, it can cause localized dry spots, resulting in heat accumulation and localized overheating in the photothermal material. This not only increases heat loss but, in severe cases, can even cause irreversible damage to the polymer network, shortening the evaporator's lifespan.

[0004] In recent years, superspreadable surfaces have shown promise for rapid water transport due to their extreme affinity for water, allowing water to spread completely into a thin film in a very short time. They possess properties such as anti-fogging, self-cleaning, and liquid regulation. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a rapid water transport superspreading hydrogel material and its preparation method. By doping the hydrogel with photothermal conversion superhydrophilic core-shell particles, the hydrogel is endowed with superspreading properties, namely, a significantly improved water contact angle and spreading speed, enabling rapid seawater transport in solar-driven interfacial evaporation. On the other hand, the combination of porous or hollow micro / nano particle loading and hydrophobic silica shell encapsulation significantly slows down surfactant loss, thereby extending the service life of the superspreading hydrogel.

[0006] The objective of this invention is achieved in part by providing a method for preparing a rapid water transport superspreading hydrogel material, comprising the following steps:

[0007] Step 1) Disperse 0.1 to 5 parts by weight of porous or hollow micro / nano particles and 4 to 6 parts by weight of surfactant in 50 to 150 parts by weight of deionized water, and perform rotary evaporation to obtain a superhydrophilic particle concentrate.

[0008] Step 2) Add 0.5 to 5 parts by weight of hydrophobic silica precursor and 0.1 to 3 parts by weight of ammonia water to 50 to 100 parts by weight of superhydrophilic particle concentrate and stir to grow hydrophobic silica nanoparticles in situ on the surface of superhydrophilic particles to obtain superhydrophilic core-shell particle suspension.

[0009] Step 3) Add 0.1 to 5 parts by weight of dopamine hydrochloride and 0.1 to 5 parts by weight of tricarboxymethylaminomethane to 100 to 200 parts by weight of the superhydrophilic core-shell particle suspension and stir to obtain a photothermal conversion superhydrophilic core-shell particle suspension.

[0010] Step 4) Disperse 0.5 to 30 parts by weight of hydrogel monomer, 0.01 to 0.3 parts by weight of initiator, 0.01 to 0.3 parts by weight of crosslinking agent, and 0.01 to 0.5 parts by weight of co-crosslinking agent in 30 to 200 parts by weight of photothermal conversion superhydrophilic core-shell particle suspension at -10°C to 100°C, and mechanically stir to obtain a rapid water transport superspreading hydrogel precursor;

[0011] Step 5) Place the rapid water transport superspreading hydrogel precursor in an environment of -196 to 0 ℃ for directional freezing and then thaw at room temperature, or crosslink it in an environment of 0 to 100 ℃ for 0.5 to 12 h to obtain the rapid water transport superspreading hydrogel.

[0012] Furthermore, the porous or hollow micro / nanoparticles mentioned in step 1) are one of diatomaceous earth, carbon nanotubes, halogenated nanotubes, and hollow silica particles with a particle size of 50 nm to 75 μm.

[0013] Furthermore, the surfactant mentioned in step 1 is one of sodium alkenyl sulfonate, sodium fatty alcohol polyoxyethylene ether sulfate, sodium dodecyl sulfate, and sodium secondary alkyl sulfonate.

[0014] Furthermore, the conditions for rotary evaporation in step 1) are: rotary evaporation for 0.5 to 6 h at a vacuum of 0.01 to 0.1 MPa and a temperature of 30°C to 100°C.

[0015] Furthermore, the hydrophobic silica precursor mentioned in step 2) is one of methyltrimethoxysilane, methyltrichlorosilane, and propyltrichlorosilane.

[0016] Furthermore, the stirring described in step 2) is carried out at a temperature of 30°C to 100°C for 0.1 h to 8 h.

[0017] Furthermore, in step 3), the ratio of dopamine hydrochloride to tricarboxymethylaminomethane is 5:3.

[0018] Furthermore, the stirring described in step 3) is carried out continuously at 30°C to 60°C for 4 to 12 hours.

[0019] Furthermore, in step 4), the hydrogel monomer is one of acrylamide, polyvinylpyrrolidone, and polyvinyl alcohol; the crosslinking agent is one of NN-methylenebisacrylamide, polyethylene glycol diacrylate, and NN-(1,2-dihydroxyethylene)bisacrylamide; the co-crosslinking agent is one of NNNN-tetramethylethylenediamine, sodium alginate, and gelatin; and the initiator is one of ammonium persulfate, potassium persulfate, and azobisisobutyrate.

[0020] Another aspect of the object of the present invention is achieved as follows: a fast water transport superspreading hydrogel material, prepared by the above method, wherein, by total weight, the hydrogel material comprises: a hydrogel polymer network matrix, 0.05 wt.% to 15 wt.% modified micro / nanoparticles, 0.1 wt.% to 15 wt.% surfactant, and water;

[0021] The modified micro / nanoparticles include: a porous or hollow micro / nanoparticle core; a hydrophobic silica nanoparticle intermediate layer grown in situ on the surface of the core; and a polydopamine outer layer coating the surface of the hydrophobic silica nanoparticle intermediate layer.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) By modifying the hydrogel with superhydrophilic core-shell particles, combined with the micro-nano rough structure and hydrophilic substances introduced by the former, the hydrogel is endowed with superspreadability, reducing the water contact angle on the surface of the hydrogel from 13° to 0° and the spreading time from 15s to 0.1s, significantly improving the water transport speed. (2) By using porous or hollow micro-nano particles to load surfactants, and cooperating with the hydrophobic silica nanoparticle shell encapsulation, the loss of surfactants is significantly slowed down, and the service life of the superspreadable hydrogel is extended. (3) The doping of hard inorganic particles can significantly enhance the mechanical properties of the hydrogel and avoid damage to the hydrogel due to mechanical external force in actual application. (4) Applying the fast water transport superspreadable hydrogel to a solar-driven interface evaporator can ensure sufficient replenishment of seawater under high solar intensity and significantly improve the evaporation rate. (5) By controlling the particle size, distribution and content of micro-nano particles, the hydrogel can obtain high transparency, which can be extended to anti-fogging and self-cleaning applications on optical instruments and photovoltaic glass. (6) The preparation method of this application is simple and the raw materials are easy to obtain, making it suitable for industrial production and application. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0024] Figure 1 An image of a rapidly water-transfer superspreadable hydrogel material.

[0025] Figure 2 Images of the superspreading properties of rapid water transport superspreading hydrogel materials and pure hydrogel materials.

[0026] Figure 3 Infrared spectral images of superspreadable hydrogel materials for rapid water transport.

[0027] Figure 4 Microscopic morphology (SEM) and EDS spectra of the superspreadable hydrogel material for rapid water transport.

[0028] Figure 5 Photographs of superspreadable hydrogel materials subjected to external forces such as pressing, twisting, or stretching for rapid water transport.

[0029] Figure 6 Evaporation rate diagram for rapidly water-transfer superspreadable hydrogel materials.

[0030] Figure 7 Photographs showing the salt resistance of a rapidly water-transfer superspreadable hydrogel material.

[0031] Figure 8 Transparency and self-cleaning properties of rapidly water-transfer superspreadable hydrogel materials.

[0032] Figure 9 The image shows the photothermal conversion performance of a rapidly water-transfer superspreadable hydrogel material. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] Example 1

[0035] A method for preparing a rapid water-transporting superspreading hydrogel is disclosed in this embodiment. The hollow or porous micro / nanoparticles used are 50 nm carbon nanotubes; the surfactant is sodium fatty alcohol polyoxyethylene ether sulfate; the hydrophobic silica precursor is methyltrichlorosilane; the hydrogel monomer is acrylamide; the initiator is ammonium persulfate; the crosslinking agent is NN-methylenebisacrylamide; and the co-crosslinking agent is NNNN-tetramethylethylenediamine. The preparation steps are as follows:

[0036] Step 1: Disperse 0.1 parts by weight of 50 nm carbon nanotubes and 4 parts by weight of sodium fatty alcohol polyoxyethylene ether sulfate in 50 parts by weight of deionized water, and rotary evaporate at 0.01 MPa vacuum and 30 °C for 0.5 h to obtain a superhydrophilic particle concentrate.

[0037] Step 2: Add 0.5 parts by weight of methyltrichlorosilane and 0.1 parts by weight of ammonia water to 50 parts by weight of superhydrophilic particle concentrate, and stir continuously at 30 °C for 0.1 h to grow hydrophobic silica nanoparticles in situ on the surface of superhydrophilic particles, thus obtaining a superhydrophilic core-shell particle suspension.

[0038] Step 3: Add 0.1 parts by weight of dopamine hydrochloride and 0.1 parts by weight of tricarboxymethylaminomethane to 100 parts by weight of superhydrophilic core-shell particle suspension, and stir continuously at 30 °C for 4 h to obtain photothermal conversion superhydrophilic core-shell particle suspension.

[0039] Step 4: 0.5 parts by weight of acrylamide, 0.01 parts by weight of ammonium persulfate, 0.01 parts by weight of NN-methylenebisacrylamide, and 0.01 parts by weight of NNNN-tetramethylethylenediamine are dispersed in 30 parts by weight of a photothermal conversion superhydrophilic core-shell particle suspension at -10 °C and mechanically stirred for 0.1 h to obtain a rapid water transport superspreading hydrogel precursor.

[0040] Step 5: Crosslink the rapid water transport superspreading hydrogel precursor at 30 °C for 0.5 h to obtain the rapid water transport superspreading hydrogel.

[0041] like Figure 1 As shown, the material consists of black powder (photothermal conversion superhydrophilic core-shell particles) and a hydrogel continuous phase. The photothermal conversion superhydrophilic core-shell particles play a role in photothermal conversion and superspreadability, while the hydrogel acts as a binder for the particles, stores seawater, and reduces the enthalpy of evaporation. This forms a uniform, intact, and elastic black columnar material free from defects such as cracking and pulverization, and it can adsorb a large amount of seawater both internally and on its surface. The water contact angle on the material surface is approximately 3.7°, the water spreading time is 4 seconds, and the evaporation rate under one solar intensity is 1.32 kg·m³. -2 ·h -1 .

[0042] Example 2

[0043] A method for preparing a rapid water-transporting superspreading hydrogel is disclosed in this embodiment. The hollow or porous micro / nano particles are diatomaceous earth with a particle size of 20 μm. The surfactant is sodium alkenyl sulfonate. The hydrophobic silica precursor is methyltrimethoxysilane. The hydrogel monomer is polyvinyl alcohol. The initiator is potassium persulfate. The crosslinking agent is polyethylene glycol diacrylate. The co-crosslinking agent is sodium alginate. The preparation steps are as follows:

[0044] Step 1: Disperse 2 parts by mass of diatomaceous earth with a particle size of 20 μm and 5 parts by mass of sodium alkenyl sulfonate in 100 parts by mass of deionized water, and rotary evaporate for 3 h under vacuum of 0.01 MPa and heating at 50 °C to obtain a superhydrophilic particle concentrate.

[0045] Step 2: Add 2 parts by mass of methyltrimethoxysilane and 2 parts by mass of ammonia water to 100 parts by mass of superhydrophilic particle concentrate, and stir continuously for 4 h under heating at 50 ℃ to grow hydrophobic silica nanoparticles in situ on the surface of superhydrophilic particles, thus obtaining a superhydrophilic core-shell particle suspension.

[0046] Step 3: Add 2.5 parts by mass of dopamine hydrochloride and 4 parts by mass of tricarboxymethylaminomethane to 200 parts by mass of superhydrophilic core-shell particle suspension, and stir continuously at 45 °C for 7 h to obtain photothermal conversion superhydrophilic core-shell particle suspension.

[0047] Step 4: Disperse 10 parts by mass of polyvinyl alcohol, 0.2 parts by mass of potassium persulfate, 0.2 parts by mass of polyethylene glycol diacrylate and 0.2 parts by mass of sodium alginate into 100 parts by mass of photothermal conversion superhydrophilic core-shell particle suspension at 90 °C, and mechanically stir for 0.5 h to obtain a rapid water transport superspreading hydrogel precursor.

[0048] Step 5: Place the rapid water transport superspreading hydrogel precursor at -196 ℃ for 0.5 h and thaw at room temperature to obtain the rapid water transport superspreading hydrogel.

[0049] like Figure 2As shown, the material incorporates numerous strongly hydrophilic groups such as sulfonic acid groups, phenolic hydroxyl groups, and silanol groups during its preparation. These groups form strong hydrogen bonds and ionic dipole interactions with water molecules, significantly increasing the material's surface energy. Furthermore, the doping of micro / nano particles creates a multi-scale rough structure on and within the material's surface. According to Young's equation and Wenzel state theory, this further enhances the material's hydrophilicity. Therefore, the rapid water transport superspreading hydrogel exhibits superspreading properties, with a water contact angle approaching 0° and a spreading time of 0.1 s. Combining this with a directional freezing process to impart vertically interconnected channels within the material enables rapid water transport, achieving an evaporation rate of 1.67 kg·m³ under one sun. -2 ·h -1 The pure polyvinyl alcohol hydrogel without the addition of photothermal conversion superhydrophilic core-shell particles showed a significant decrease in hydrophilicity, with the water contact angle increasing to 13° and the water spreading time extending to 15 s.

[0050] Example 3

[0051] A method for preparing a rapid water-transporting superspreading hydrogel is disclosed. In this embodiment, hollow or porous micro / nano particles with a particle size of 75 μm are selected, sodium dodecyl sulfate is selected as the surfactant, propyltrichlorosilane is selected as the hydrophobic silica precursor, polyvinylpyrrolidone is selected as the hydrogel monomer, azobisisobutyrate is selected as the initiator, N / N-(1,2-dihydroxyethylene)bisacrylamide is selected as the crosslinking agent, and gelatin is selected as the co-crosslinking agent. The preparation steps are as follows:

[0052] Step 1: Disperse 5 parts by mass of hollow silica particles with a particle size of 75 μm and 6 parts by mass of sodium dodecyl sulfate in 150 parts by mass of deionized water, and rotary evaporate under 0.1 MPa vacuum and 100 °C heating conditions for 6 h to obtain a superhydrophilic particle concentrate.

[0053] Step 2: Add 5 parts by mass of propyltrichlorosilane and 3 parts by mass of ammonia water to 100 parts by mass of superhydrophilic particle suspension, and stir continuously at 100 °C for 8 h to grow hydrophobic silica nanoparticles in situ on the surface of superhydrophilic particles, thus obtaining superhydrophilic core-shell particle suspension.

[0054] Step 3: Add 5 parts by mass of dopamine hydrochloride and 5 parts by mass of tricarboxymethylaminomethane to 200 parts by mass of superhydrophilic core-shell particle suspension, and stir continuously at 60 °C for 12 h to obtain photothermal conversion superhydrophilic core-shell particle suspension.

[0055] Step 4: 30 parts by weight of polyvinylpyrrolidone, 0.3 parts by weight of azobisisobutyrate, 0.3 parts by weight of NN-(1,2-dihydroxyethylene)bisacrylamide, and 0.5 parts by weight of gelatin were dispersed in 200 parts by weight of photothermal conversion superhydrophilic core-shell particle suspension at 100 °C and mechanically stirred for 0.5 h to obtain a rapid water transport superspreading hydrogel precursor.

[0056] Step 5: Crosslink the rapid water transport superspreading hydrogel precursor at 100 °C for 12 h to obtain the rapid water transport superspreading hydrogel.

[0057] like Figure 3 As shown, infrared spectroscopy was used to analyze the photothermal conversion superhydrophilic core-shell particles (blue) and the rapid water transport superspreading hydrogel (red), respectively. The 1199 cm⁻¹ hydrogel was analyzed. -1 The stretching vibrations of the S=O group in the sulfonic acid group are at 2850 and 2922 cm⁻¹. -1 The stretching vibration of CH in the corresponding alkyl chain indicates that the hydrophilic surfactant was successfully introduced into the particles and hydrogel, thereby endowing the hydrogel material with superspreadability.

[0058] Example 4

[0059] A method for preparing a rapid water-transporting superspreading hydrogel is disclosed. In this embodiment, hollow or porous micro / nano particles with a particle size of 200 nm are selected as halogenated nanotubes, the surfactant is sodium secondary alkyl sulfonate, the hydrophobic silica precursor is propyltrimethoxysilane, the hydrogel monomer is acrylamide, the initiator is ammonium persulfate, the crosslinking agent is NN-methylenebisacrylamide, and the co-crosslinking agent is NNNN-tetramethylethylenediamine. The preparation steps are as follows:

[0060] Step 1: Disperse 0.1 parts by mass of 200 nm diameter halogenated nanotubes and 4 parts by mass of sodium secondary alkyl sulfonate in 50 parts by mass of deionized water, and rotary evaporate at 0.01 MPa vacuum and 30 °C for 0.5 h to obtain a superhydrophilic particle concentrate.

[0061] Step 2: 0.5 parts by mass of propyltrimethoxysilane and 0.1 parts by mass of ammonia water are added to 100 parts by mass of superhydrophilic particle concentrate. The mixture is stirred continuously for 0.1 h under heating conditions of 30 °C to grow hydrophobic silica nanoparticles in situ on the surface of superhydrophilic particles, thus obtaining a superhydrophilic core-shell particle suspension.

[0062] Step 3: Add 0.8 parts by weight of dopamine hydrochloride and 0.48 parts by weight of tricarboxymethylaminomethane to 200 parts by weight of superhydrophilic core-shell particle suspension, and stir continuously at 45 °C for 7 h to obtain photothermal conversion superhydrophilic core-shell particle suspension.

[0063] Step 4: 0.5 parts by weight of acrylamide, 0.01 parts by weight of ammonium persulfate, 0.01 parts by weight of NN-methylenebisacrylamide, and 0.01 parts by weight of NNNN-tetramethylethylenediamine are dispersed in 30 parts by weight of a photothermal conversion superhydrophilic core-shell particle suspension at -10 ℃ and mechanically stirred for 0.5 h to obtain a rapid water transport superspreading hydrogel precursor.

[0064] Step 5: Crosslink the rapid water transport superspreading hydrogel precursor at 60 °C for 6 h to obtain the rapid water transport superspreading hydrogel.

[0065] like Figure 4 As shown, EDS spectroscopy reveals that the sulfur element representing the secondary alkyl sulfonate surfactant is distributed in the same manner as that of the halogenated nanotubes, indicating successful loading within the halogenated nanotubes. After incorporating photothermal-converting superhydrophilic core-shell particles into the hydrogel, the particles form chemical bonds with the hydrogel's active groups (sulfonic acid groups, phenolic hydroxyl groups, silanol groups, etc.) on their surfaces, strengthening interfacial bonding. Therefore, they are tightly embedded within the hydrogel, serving as crosslinking points and reinforcing phases, thus enhancing the hydrogel's mechanical properties and superspreadability. Furthermore, they form a porous structure, providing channels for water transport. This material exhibits a contact angle of 2.5°, a spreading time of 0.3 s, and an evaporation rate of 1.37 kg·m³ under one sun. -2 ·h -1 .

[0066] Comparative Example 1

[0067] Compared with Example 2, this comparative example did not include photothermal conversion superhydrophilic core-shell particles. It was used to illustrate the role of the photothermal conversion superhydrophilic core-shell particles. The preparation steps are as follows:

[0068] Step 1: Disperse 10 parts by weight of polyvinyl alcohol, 0.2 parts by weight of potassium persulfate, 0.2 parts by weight of polyethylene glycol diacrylate and 0.2 parts by weight of sodium alginate in 100 parts by weight of deionized water at 90 °C and mechanically stir for 0.5 h to obtain a hydrogel precursor.

[0069] Step 2: Place the hydrogel precursor at -196 ℃ for directional freezing for 0.5 h, and thaw at room temperature to obtain polyvinyl alcohol hydrogel.

[0070] Comparative Example 2

[0071] Compared with Example 2, this comparative example replaces the polyvinyl alcohol hydrogel with a hydrophilic acrylic resin to illustrate the role of the hydrogel. The preparation steps are as follows:

[0072] Step 1: Disperse 2 parts by mass of diatomaceous earth with a particle size of 20 μm and 5 parts by mass of sodium alkenyl sulfonate in 100 parts by mass of deionized water, and rotary evaporate for 3 h under vacuum of 0.01 MPa and heating at 50 °C to obtain a superhydrophilic particle concentrate.

[0073] Step 2: Add 2 parts by mass of methyltrimethoxysilane and 2 parts by mass of ammonia water to 100 parts by mass of superhydrophilic particle concentrate, and stir continuously for 4 h under heating at 50 ℃ to grow hydrophobic silica nanoparticles in situ on the surface of superhydrophilic particles, thus obtaining a superhydrophilic core-shell particle suspension.

[0074] Step 3: Add 2.5 parts by mass of dopamine hydrochloride and 4 parts by mass of tricarboxymethylaminomethane to 200 parts by mass of superhydrophilic core-shell particle suspension, and stir continuously at 45 °C for 7 h to obtain photothermal conversion superhydrophilic core-shell particle suspension.

[0075] Step 4: Disperse 10 parts by weight of hydrophilic acrylic resin and 0.2 parts by weight of curing agent in 100 parts by weight of photothermal conversion superhydrophilic core-shell particle suspension at 90 °C, and mechanically stir for 0.5 h to obtain superhydrophilic acrylic resin precursor.

[0076] Step 5: Cur the superhydrophilic acrylic resin precursor at 60 °C for 6 h to obtain the superhydrophilic acrylic resin.

[0077] Comparative Example 3

[0078] In this comparative example, a commercial carbon film was used as a reference, which was applied directly to solar-driven interface evaporation without any other treatment.

[0079] Table 1. Comparison of the technical effects of the above embodiments and comparative examples

[0080]

[0081] As shown in Table 1, Examples 1 to 4 prepared photothermal conversion superhydrophilic core-shell particles by loading and encapsulating hydrophilic surfactants onto hollow or porous micro / nanoparticles. These particles were used to modify hydrogels, achieving excellent superspreadability (water contact angle <5°, spreading time <1s), significantly improving the water transport rate of the hydrogel and overcoming the limitation of water transport rate on evaporation rate. Simultaneously, the doping of rigid inorganic particles significantly enhanced the mechanical properties of the hydrogel, allowing it to be repeatedly bent / pressed. The properties are briefly described in Examples 1 to 4, with Example 2 showing the best performance. This example serves as a standard for comparison to illustrate the effects of various factors in this invention.

[0082] (1) Compared with the pure polyvinyl alcohol hydrogel in Comparative Example 1, it can be found that the doping of photothermal conversion superhydrophilic core-shell particles provides the hydrogel with a large number of hydrophilic groups and micro-nano rough structures, giving the hydrogel superspreadability. Therefore, the water contact angle of the fast water transport superspreading hydrogel material is reduced by more than 10°, and the spreading time is reduced by 99.3%. This fast water transport performance increases the solar-driven interface evaporation rate by 227.5% (one solar intensity) and 491.8% (three solar intensities), respectively. The most significant increase is that when the solar intensity is increased from one solar intensity to three solar intensities, the evaporation rate of the fast water transport superspreading hydrogel material is increased by 158.7%, while that of the pure polyvinyl alcohol hydrogel material is 43.1%, breaking through the limitation of water transport speed on evaporation rate. In addition, the doping of rigid inorganic particles significantly enhances the mechanical properties of the hydrogel, allowing it to withstand repeated bending / pressing >50 times and still recover to its original shape. Figure 5 Pure polyvinyl alcohol hydrogel materials can only withstand <20 cycles.

[0083] (2) Compared with the superhydrophilic acrylic resin in Comparative Example 2, it can be found that although the synergistic effect of photothermal conversion superhydrophilic core-shell particles and hydrophilic acrylic resin can achieve excellent superhydrophilic properties, with water contact angle and spreading time as low as 3.9° and 2.1 s respectively, the waterborne acrylic resin does not have water storage space / water transport channels between the molecular chains of the three-dimensional cross-linked hydrogel network. Therefore, the water transport performance is significantly reduced or even lost, resulting in the evaporation rate dropping to 0.14 kg·m -2 ·h -1 (One sun) and 0.39 kg·m -2 ·h -1 (Three suns), far lower than fast water transport superspreading hydrogel materials, which also proves the influence and limitation of water transport performance on the performance of solar-driven interface evaporation.

[0084] (3) Compared with the commercial carbon film in Comparative Example 3, it can be found that although the commercial carbon film has certain natural hydrophilicity and rich porous structure, it does not have superspreadability. The water contact angle is only 5.5° and the water spreading time is as long as 10.3s. Therefore, the evaporation rate of the superspreadable hydrogel material with faster water transport is reduced by 44.9% (one sun) and 63.7% (three suns), respectively.

[0085] In summary, considering the improvements in superspreadability, water transport channels, and mechanical properties, the rapid water transport superspreading hydrogel in Example 2 exhibits a water contact angle close to 0°, a spreading time as low as 0.1 s, and an evaporation rate as high as 1.67 kg·m³. -2 ·h -1 (One sun) and 4.32 kg·m -2 ·h -1 (Three suns) is far superior to the comparison.

[0086] Example 5

[0087] Compared with Example 2, this embodiment only changed the amount of photothermal conversion superhydrophilic core-shell particle suspension added in step 4; the results are shown in Table 2:

[0088]

[0089] Table 2 and Figure 6 Superspreadability (water contact angle and spreading time), evaporation rate, and mechanical properties of rapidly water-transporting superspreadable hydrogel materials were prepared by adding different amounts of photothermal conversion superhydrophilic core-shell particle suspensions. Compared to Example 2, when the amount of suspension added was small (e.g., 10 parts by mass), the superspreadability of the hydrogel material was significantly reduced due to the fewer hydrophilic groups provided and the decrease in the micro-nano rough structure constructed by the particles, resulting in a corresponding decrease in water transport rate and a 68.9% reduction in evaporation rate. In addition, the mechanical properties of the hydrogel material also decreased significantly due to the lower proportion of hard particles. With the increase of suspension addition, the superspreadability, evaporation rate, and mechanical properties of the hydrogel material were continuously optimized, reaching the optimal values ​​at an addition amount of 100 parts by mass. As the amount of suspension added increases, particles aggregate, clogging the internal pores of the hydrogel. This leads to an increased water contact angle and impaired water transport, resulting in a decreased evaporation rate. Simultaneously, the continuous phase of the hydrogel is disrupted, and its mechanical properties deteriorate. When the amount of suspension added exceeds 200 parts by mass (e.g., 300 parts by mass), the hydrogel material loses its superspreadability, and the evaporation rate drops to <1 kg·m⁻¹. -2 ·h -1 Furthermore, mechanical external forces can easily cause them to break apart rapidly. Therefore, the appropriate addition amount of photothermal conversion superhydrophilic core-shell particle suspension is 30-200 parts by mass.

[0090] Example 6

[0091] Compared with Example 2, this embodiment only changed the amount of surfactant added in step 1. The results are shown in Table 3:

[0092] Table 3 Comparison of technical effects between Example 6 and Example 2

[0093]

[0094] Table 3 and Figure 7The superspreading performance, evaporation rate, and salt resistance of fast water transport superspreading hydrogel materials were obtained by adding different amounts of surfactant. Compared with Example 2, too little surfactant (e.g., 2 parts by mass) could not provide sufficient hydrophilic groups, resulting in a decrease in the superspreading performance and water transport rate of the hydrogel material, thereby reducing the evaporation rate. Excessive surfactant (e.g., 8 parts by mass) would self-assemble into micelles in water, filling the hydrogel network and blocking water transport channels, leading to a decrease in superspreading performance and water transport rate, similarly reducing the evaporation rate. Only a moderate amount of surfactant (4-6 parts by mass) could improve superspreading and water transport performance without clogging the pores, thus improving evaporation performance. Especially at an addition amount of 5 parts by mass, the superspreading performance, water transport rate, and evaporation rate were optimal. Figure 7 It can be observed that, due to the excellent water transport rate and porosity, the added salt crystals not only do not increase after a period of interfacial evaporation, but are even completely dissolved through water transport, exhibiting excellent salt resistance. This is crucial for maintaining the long-term excellent evaporation performance of the interfacial evaporator. Therefore, the appropriate amount of surfactant added is 4-6 parts by weight.

[0095] Example 7

[0096] Compared with Example 2, this embodiment only changes the type and particle size of hollow or porous micro / nanoparticles in step 1. The results are shown in Table 4.

[0097] Table 4 Comparison of technical effects between Example 7 and Example 2

[0098]

[0099] Table 4 shows the superspreading properties, evaporation rates, and transparency of fast water transport superspreading hydrogel materials prepared using different types and sizes of hollow or porous micro / nanoparticles. Compared to Example 2, because solid carbon black particles were used in Example 7-1, it was impossible to load surfactants, resulting in a loss of superspreading properties in the prepared hydrogel material. The water contact angle was as high as 25.8°, the spreading time was as long as 24 s, and the evaporation rate was also as low as <1 kg·m³. -2 ·h -1Other hydrogel materials prepared using porous or hollow particles loaded with surfactants all exhibit excellent superspreading and interfacial evaporation properties. Furthermore, it was found that when the particle size reaches the micrometer scale, the hydrogel materials are all opaque. Specifically, according to Examples 2 and 7-4 to 7-6, as the diatomaceous earth particle size increases, the surface roughness of the hydrogel significantly increases. These rough structures hinder water spreading; therefore, although the water contact angle only slightly increases, the spreading time continuously lengthens, especially after the particle size exceeds 75 μm, where the spreading time becomes drastically longer, the water transport rate slows down, and the evaporation rate decreases. In stark contrast, transparent superspreading hydrogel materials can be prepared using 200 nm auroralite nanotubes, and when applied to photovoltaic glass surfaces, they exhibit excellent self-cleaning properties. Figure 8 This broadened its application scope.

[0100] Example 8

[0101] Compared with Example 2, this embodiment only changed the amount of dopamine hydrochloride and tricarboxymethylaminomethane added in step 3. The results are shown in Table 5.

[0102] Table 5 Comparison of technical effects between Example 8 and Example 2

[0103]

[0104] Table 5 and Figure 9 The evaporation rate, photothermal conversion performance, and color of fast water transport superspreading hydrogel materials were prepared with different amounts of dopamine hydrochloride / tricarboxymethylaminomethane. Compared with Example 2, the absence or addition of dopamine hydrochloride and a very small amount of tricarboxymethylaminomethane resulted in insufficient polymerization of dopamine hydrochloride on the particle surface, resulting in a white or light brown color. This reduced the photothermal conversion efficiency of the hydrogel material, thus lowering the maximum surface temperature by 10 °C. The decrease in surface temperature is obviously detrimental to seawater evaporation, and therefore the evaporation rate also decreased to 0.78 kg·m³. -2 ·h -1 With increasing amounts of dopamine hydrochloride / tricarboxymethylaminomethane (0.1 / 0.06-5 / 3 parts by mass), the color of the particles and hydrogel materials gradually deepens, eventually turning black. At this point, the photothermal conversion performance significantly improves, the surface temperature rises above 30 °C, and the corresponding evaporation rate also increases to 1.37-1.67 kg·m³. -2 ·h -1 However, when the amount of dopamine hydrochloride / tricarboxymethylaminomethane added is too high (e.g., 8 / 4.8 parts by mass), the hydrophilic groups on the particle surface will be excessively masked, reducing the superspreading performance of the hydrogel material and resulting in a decrease in water transport rate and evaporation rate.

[0105] Example 9

[0106] Compared with Example 2, this embodiment only changed the amount of hydrogel monomer added in step 4. The results are shown in Table 6:

[0107] Table 6 Comparison of technical effects between Example 9 and Example 2

[0108]

[0109] Table 6 shows the superspreading properties, evaporation rate, and mechanical properties of the rapid water transport superspreading hydrogel materials prepared with different amounts of hydrogel monomers. Compared with Example 2, when the amount of hydrogel monomer added is extremely small (e.g., 0.1 parts by mass), the material is basically composed of photothermal conversion superhydrophilic core-shell particles. Although it has excellent superspreading properties (water contact angle close to 0°, spreading time as low as 0.1 s), there is no adhesion between the particles, so it cannot be formed as an evaporator. As the amount of hydrogel monomer added increases, the adhesion between the particles strengthens, and the formed evaporator not only maintains excellent superspreading properties but also achieves an evaporation rate of... It can withstand more than 50 bends / presses. However, when the addition amount exceeds 10 parts by weight, the hydrogel monomer begins to excessively photothermally convert into superhydrophilic core-shell particles, weakening the latter's superspreading properties, thus reducing the evaporation rate. Simultaneously, the reinforcing effect of the hard particles weakens, and mechanical properties also begin to decline, especially when the addition amount exceeds 30 parts by weight, where the weakening effect increases sharply. Therefore, the reasonable addition amount of hydrogel monomer is 0.5-30 parts by weight.

[0110] Example 10

[0111] Compared with Example 2, this embodiment only changes the amount of hydrophobic silica precursor added in step 2. The results are shown in Table 7.

[0112] Table 7 Comparison of technical effects between Example 10 and Example 2

[0113]

[0114] Table 7 shows the superspreading performance, evaporation rate, surfactant loss rate, and durability of the rapid water transport superspreading hydrogel materials prepared with different amounts of hydrophobic silica precursor. Compared with Example 2, when the amount of hydrophobic silica precursor added is extremely small (e.g., 0.1 parts by mass), very few hydrophobic silica particles are generated in the reaction, which cannot form an encapsulation effect. The surfactant loaded in the photothermal conversion superhydrophilic core-shell particles easily migrates out. At this time, the hydrogel material has excellent superspreading and evaporation rates, but the surfactant loss rate is too fast, resulting in insufficient durability of the hydrogel material as an evaporator, which can only continue to evaporate for 26 hours. With the increase of the amount of hydrophobic silica precursor added, its encapsulation effect is enhanced, the surfactant loss rate is reduced by 95.9%-98.2%, and the durability is improved by more than 10 times; and when the amount added is 0.5-2 parts by mass, it still maintains excellent superspreading and evaporation rates, achieving a synergistic improvement in performance and durability. When the addition amount exceeds 2 parts by mass, the surfactant gradually becomes difficult to migrate out due to the excessive encapsulation of the hydrophobic silica nanoparticles. Although the surfactant loss rate and durability can still be further optimized, the superspreading and evaporation rates begin to decrease. Especially when the addition amount exceeds 5 parts by mass, the hydrogel material loses its superspreading properties, and the evaporation rate decreases by 50.3%. Therefore, the reasonable addition amount of hydrophobic silica precursor is 0.5-5 parts by mass.

[0115] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing a rapid water transport superspreadable hydrogel material, characterized in that, Includes the following steps: Step 1) Disperse 0.1 to 5 parts by weight of porous or hollow micro / nano particles and 4 to 6 parts by weight of surfactant in 50 to 150 parts by weight of deionized water, and perform rotary evaporation to obtain a superhydrophilic particle concentrate. Step 2) Add 0.5 to 5 parts by weight of hydrophobic silica precursor and 0.1 to 3 parts by weight of ammonia water to 50 to 100 parts by weight of superhydrophilic particle concentrate and stir to grow hydrophobic silica nanoparticles in situ on the surface of superhydrophilic particles to obtain superhydrophilic core-shell particle suspension. Step 3) Add 0.1 to 5 parts by weight of dopamine hydrochloride and 0.1 to 5 parts by weight of tricarboxymethylaminomethane to 100 to 200 parts by weight of the superhydrophilic core-shell particle suspension and stir to obtain a photothermal conversion superhydrophilic core-shell particle suspension. Step 4) Disperse 0.5 to 30 parts by weight of hydrogel monomer, 0.01 to 0.3 parts by weight of initiator, 0.01 to 0.3 parts by weight of crosslinking agent, and 0.01 to 0.5 parts by weight of co-crosslinking agent in 30 to 200 parts by weight of photothermal conversion superhydrophilic core-shell particle suspension at -10°C to 100°C, and mechanically stir to obtain a rapid water transport superspreading hydrogel precursor; Step 5) Place the rapid water transport superspreading hydrogel precursor in an environment of -196 to 0 ℃ for directional freezing and then thaw at room temperature, or crosslink it in an environment of 0 to 100 ℃ for 0.5 to 12 h to obtain the rapid water transport superspreading hydrogel.

2. The method for preparing a rapid water transport superspreadable hydrogel material according to claim 1, characterized in that, The porous or hollow micro / nanoparticles mentioned in step 1) are one of the following: diatomaceous earth, carbon nanotubes, halogenated nanotubes, and hollow silica particles with a particle size of 50 nm to 75 μm.

3. The method for preparing a rapid water transport superspreadable hydrogel material according to claim 1, characterized in that, The surfactant mentioned in step 1 is one of sodium alkenyl sulfonate, sodium fatty alcohol polyoxyethylene ether sulfate, sodium dodecyl sulfate, and sodium secondary alkyl sulfonate.

4. The method for preparing a rapid water transport superspreadable hydrogel material according to claim 1, characterized in that, The conditions for rotary evaporation described in step 1) are: rotary evaporation for 0.5 to 6 h at a vacuum of 0.01 to 0.1 MPa and a temperature of 30°C to 100°C.

5. The method for preparing a rapid water transport superspreadable hydrogel material according to claim 1, characterized in that, The hydrophobic silica precursor mentioned in step 2) is one of methyltrimethoxysilane, methyltrichlorosilane, and propyltrichlorosilane.

6. The method for preparing a rapid water transport superspreading hydrogel material according to claim 1, characterized in that, The stirring described in step 2) is carried out at a temperature of 30°C to 100°C for 0.1 h to 8 h.

7. The method for preparing a rapid water transport superspreadable hydrogel material according to claim 1, characterized in that, The mass ratio of dopamine hydrochloride and tricarboxymethylaminomethane in step 3) is 5:

3.

8. The method for preparing a rapid water transport superspreadable hydrogel material according to claim 1, characterized in that, The stirring described in step 3) is carried out continuously at 30°C to 60°C for 4 to 12 hours.

9. The method for preparing a rapid water transport superspreading hydrogel material according to claim 1, characterized in that, The hydrogel monomer mentioned in step 4) is one of acrylamide, polyvinylpyrrolidone, and polyvinyl alcohol; the crosslinking agent is one of NN-methylenebisacrylamide, polyethylene glycol diacrylate, and NN-(1,2-dihydroxyethylene)bisacrylamide; the co-crosslinking agent is one of NNNN-tetramethylethylenediamine, sodium alginate, and gelatin; and the initiator is one of ammonium persulfate, potassium persulfate, and azobisisobutyrate.

10. A rapidly water-transporting, superspreadable hydrogel material, characterized in that, By total weight, it comprises: a hydrogel polymer network matrix, 0.05 wt.% to 15 wt.% of modified micro / nanoparticles, 0.1 wt.% to 15 wt.% of surfactant, and water; The modified micro / nanoparticles include: a porous or hollow micro / nanoparticle core; a hydrophobic silica nanoparticle intermediate layer grown in situ on the surface of the core; and a polydopamine outer layer coating the surface of the hydrophobic silica nanoparticle intermediate layer.

Images