A macroporous hydrogel with photothermal conversion function

Abstract

This invention relates to a macroporous hydrogel with photothermal conversion function, belonging to the field of functional materials technology. The preparation method of this invention utilizes the characteristic that silicon-nitrogen bond-containing organosilicon compounds can generate gas during gelation. A one-pot method is used to prepare the foamed hydrogel, which is simple to operate, and the density of the pores in the hydrogel can be adjusted by changing the amount of the silicon-nitrogen bond-containing organosilicon compound. The photothermal conversion material is dispersed in the pore walls. When sunlight shines on it, heat is conducted along the photothermal conversion material and reflected within the pores. Therefore, the macroporous hydrogel prepared by this invention has a high photothermal conversion efficiency, with absorbance reaching 100%. The pore structure endows the macroporous hydrogel with high hygroscopicity, thus the macroporous hydrogel prepared by this invention can be used in fields such as atmospheric water collection and seawater purification.

Description

Technical Field

[0001] This invention relates to a macroporous hydrogel with photothermal conversion function, belonging to the field of functional materials technology. Background Technology

[0002] Hydrogels are hydrophilic but water-insoluble polymers. They can rapidly swell to an equilibrium volume in water while maintaining their shape and three-dimensional network structure, and deswell under certain conditions. They are a rapidly developing class of functional polymer materials that combine water absorption, water retention, and sustained release. Due to their porous structure, macroporous hydrogels can reduce water permeation resistance through capillary action, allowing water to quickly enter the gel interior. In addition, macroporous hydrogels have a larger specific surface area, allowing the internal hydrophilic groups to quickly contact water, thereby promoting an increased water absorption rate.

[0003] Water resources are a vital natural resource for human societal development. Although the Earth's water volume is vast, only a small fraction (approximately 0.26%) is directly usable for production and daily life. The sustainable utilization of water resources is one of the most crucial aspects of the sustainable development and utilization of all natural resources. Water-collecting materials are materials that can absorb moisture and allow it to quickly dissipate for easy collection. For example, macroporous hydrogels with photothermal conversion capabilities, after absorbing moisture from seawater, wastewater, or air, convert the absorbed light energy into heat under sunlight or other light sources. The water inside the macroporous hydrogel is released as a gas upon heating. This released gas then comes into contact with a condensation and collection device, becoming liquid water, thus achieving water conversion and collection. Therefore, macroporous hydrogels can be used as water-collecting materials in fields such as seawater desalination, wastewater purification, and atmospheric water collection.

[0004] Currently, there are several main methods for preparing macroporous hydrogels with photothermal conversion functions. One method is the foaming method, which mainly uses surfactants or whey proteins to generate foam under stirring, thereby initiating monomer polymerization and generating foamed hydrogels. Another method is the template method, which first prepares a hydrogel with dispersed soluble particles, and then soaks it in a solvent to remove the particles, generating macroporous hydrogels. There are also methods for preparing macroporous hydrogels through freezing and fermentation. However, these methods have disadvantages such as complex processes and easy generation of waste solvents. Summary of the Invention

[0005] The purpose of this invention is to provide a macroporous hydrogel with photothermal conversion function, which can solve the problems of complex process and easy generation of waste solvent in the current preparation of macroporous hydrogels with photothermal conversion function.

[0006] To achieve the above objectives, the technical solution adopted by the macroporous hydrogel with photothermal conversion function of the present invention is as follows:

[0007] A macroporous hydrogel with photothermal conversion function is prepared by a method comprising the following steps: mixing an organosilicon compound, a water-soluble polymeric monomer, a photothermal conversion material, an initiator, and water; the water-soluble polymeric monomer polymerizes and crosslinks while releasing gas to form a foaming system, thereby obtaining a macroporous hydrogel with photothermal conversion function; the organosilicon compound has the structure shown in Formula I:

[0008]

[0009] In Equation I, R1, R2, R3, R 10 R 11 and R 12 Each of the following is independently selected from C1-C5 alkyl groups; R4 and R5 are each independently selected from C3-C6 alkylene groups; R6, R7, R8 and R9 are each independently selected from methyl, ethyl or propyl groups.

[0010] The macroporous hydrogel with photothermal conversion function of the present invention utilizes the characteristic that silicon-nitrogen bond-containing organosilicon compounds can generate gas during gelation. It is prepared using a one-pot method, which is simple to operate, and the density of the pores in the hydrogel can be adjusted by changing the amount of the silicon-nitrogen bond-containing organosilicon compound. Because organosilicon compounds have surface-active properties, they can act as surfactants, helping to disperse the photothermal conversion material uniformly in the system, avoiding agglomeration, and better exerting the photothermal conversion function. In addition, the siloxanes in the organosilicon compounds can undergo hydrolysis and condensation, further improving the strength and toughness of the hydrogel. Due to the adsorption, hydrogen bonding, and other physicochemical interactions between the photothermal conversion material and the organosilicon compound, the photothermal conversion material is dispersed in the pore walls. When sunlight shines, heat is conducted along the photothermal conversion material and reflected within the pores. Therefore, the macroporous hydrogel prepared by the present invention has a high photothermal conversion efficiency, with an absorbance reaching 100%. The pore structure endows the macroporous hydrogel with high hygroscopicity and high water absorption rate. Therefore, the macroporous hydrogel prepared by the present invention can be used in fields such as atmospheric water collection and seawater purification. When the macroporous hydrogel prepared by this invention is used in water collection fields such as atmospheric water harvesting and seawater purification, it can adsorb a large amount of water and has a high photothermal conversion efficiency. Under sunlight, the macroporous hydrogel can convert light energy into heat, causing the water adsorbed inside the macroporous hydrogel to escape as gas, thereby realizing the conversion and collection of water. In addition, because the organosilicon portion of the macroporous hydrogel has a certain degree of hydrophobicity, water can more easily evaporate from the gel under heating, thus realizing the conversion and collection of water.

[0011] Preferably, in formula I, R1, R2, R3, R 10 R 11 and R 12 All are methyl; R4 and R5 are both propylene; R6, R7, R8 and R9 are all methyl.

[0012] It is understood that all water-soluble polymeric monomers used in the prior art to prepare hydrogels are applicable to this invention. Examples include acrylic acid, N-isopropylacrylamide, and N,N-dimethylacrylamide.

[0013] Preferably, the water-soluble polymeric monomer comprises a first water-soluble polymeric monomer and a second water-soluble polymeric monomer, wherein the first water-soluble polymeric monomer has one and only one olefinic unsaturated double bond, and the second water-soluble polymeric monomer has at least one or more olefinic unsaturated double bonds. The first water-soluble polymeric monomer is used to form the network framework of the prepared hydrogel, and the second water-soluble polymeric monomer acts as a crosslinking agent.

[0014] Preferably, the first water-soluble polymeric monomer is selected from one or any combination of acrylamide, methacrylamide, acrylic acid, N-isopropylacrylamide, and N,N-dimethylacrylamide; the second water-soluble polymeric monomer is N,N'-methylenebisacrylamide. For example, the first water-soluble polymeric monomer is acrylamide and / or methacrylamide.

[0015] Preferably, the mass ratio of water, the first water-soluble polymeric monomer, and the second water-soluble polymeric monomer is 20:5:(0.01 to 0.001). For example, the mass ratio of water, the first water-soluble polymeric monomer, and the second water-soluble polymeric monomer is 20:5:0.001.

[0016] Preferably, the initiator is a persulfate initiator. For example, the persulfate initiator is ammonium persulfate. Persulfate can undergo a redox reaction with the silicon-nitrogen bonds in organosilicon compounds at a lower temperature to generate free radicals, which in turn initiate the polymerization reaction of water-soluble polymerizable monomers. While initiating the polymerization reaction, the organosilicon compounds can be chemically bonded to the polymerization system, further improving the strength and toughness of the hydrogel.

[0017] Preferably, the mass ratio of the water-soluble polymeric monomer to the persulfate initiator is 5:(0.005-0.015). For example, the mass ratio of the water-soluble polymeric monomer to the persulfate initiator is 5:0.015.

[0018] Preferably, the mass ratio of the water-soluble polymeric monomer to the organosilicon compound is 5:(1-4). Insufficient use of the organosilicon compound will make it difficult to initiate the polymerization reaction at room temperature, while excessive use will cause a decrease in the hydrogel strength.

[0019] Preferably, the photothermal conversion material is selected from one or any combination of carbon nanotubes, graphene oxide, MXene, and molybdenum disulfide. For example, the photothermal conversion material is carbon nanotubes, graphene oxide, or molybdenum disulfide. MXene materials are a class of metal carbide and metal nitride materials with a two-dimensional layered structure, and have the chemical formula M. n+1 AX n In the series (n = 1-3), M represents an early transition metal, such as Sc, Ti, Zr, V, Nb, Cr, or Mo; A usually represents a Group III or Group IV chemical element; and X represents a C or N element.

[0020] To reduce costs, the photothermal conversion material is preferably a multi-walled carbon nanotube. More preferably, the multi-walled carbon nanotube is a hydroxylated multi-walled carbon nanotube. The hydroxyl groups can undergo a condensation reaction with the hydrolyzed siloxane, thereby improving the dispersion uniformity of the photothermal conversion material (multi-walled carbon nanotubes) and its binding force in the hydrogel, thus enhancing the photothermal conversion efficiency of the macroporous hydrogel.

[0021] Preferably, the hydroxylated multi-walled carbon nanotubes have a diameter of 10–30 nm, a length of 10–30 μm, and a hydroxyl content of 2–4 wt%.

[0022] Preferably, the mass ratio of the water-soluble polymeric monomer to the photothermal conversion material is 25:(0.03-0.1). Excessive use of the photothermal conversion material can lead to a decrease in the material's mechanical properties due to agglomeration.

[0023] Preferably, a catalyst is also added during the mixing process, the catalyst being selected from lithium chloride, sodium chloride, and calcium chloride, or any combination thereof. Preferably, the mass ratio of the water-soluble polymeric monomer to the catalyst is 5:(4-12). Because the metal ions in lithium chloride, sodium chloride, and calcium chloride can coordinate with silicon-nitrogen bond-containing organosilicon compounds, the activation energy of free radical generation from persulfate and organosilicon compounds is reduced, the initiation rate is increased, the foaming time is shortened, and the pore structure of the prepared macroporous hydrogel can be improved. Lithium chloride, sodium chloride, and calcium chloride have strong hygroscopic properties, especially lithium chloride, which is often used alone as a hygroscopic agent. Therefore, the presence of these salts in the gel can further enhance the hygroscopicity and water adsorption capacity of the gel. Excessive catalyst dosage will reduce the tensile strength of the gel.

[0024] Preferably, after mixing, the mixture is allowed to stand to obtain the macroporous hydrogel with photothermal conversion function. Preferably, the mixing method includes the following steps: under stirring conditions, an organosilicon compound is added dropwise to a mixture containing a water-soluble polymeric monomer, a photothermal conversion material, an initiator, and water. Preferably, the standing time is not less than 30 minutes. When a foaming accelerator is also added during the mixing process, the mixture also includes a catalyst.

[0025] Preferably, the organosilicon compound is prepared by an addition reaction of the amino group in the compound of formula II and the silane group in the compound of formula III;

[0026]

[0027] In Equation II, R 14 R 15 and R 16 Each is independently selected from hydrogen and C1-C5 alkyl groups; R 13 It is a C3-C6 alkylene group;

[0028] In formula III, R 17 R 18 R 19 and R 20 Each is independently selected from methyl, ethyl, or propyl. Attached Figure Description

[0029] Figure 1 The images and SEM images show the appearance of the macroporous hydrogel with photothermal conversion function in Example 1 of Experiment 1; wherein, Figure 1 a is a side view of the macroporous hydrogel with photothermal conversion function in Example 1. Figure 1 b is a top view of the macroporous hydrogel with photothermal conversion function in Example 1. Figure 1 c is a SEM image of the macroporous hydrogel with photothermal conversion function in Example 1;

[0030] Figure 2 This is a schematic diagram showing the changes in the tensile properties of the macroporous hydrogels in Examples 1-4 of Experiment 2;

[0031] Figure 3 This is a schematic diagram showing the change in moisture absorption rate over time for the macroporous hydrogels with photothermal conversion function in Examples 1-6 of Experiment 3; wherein, Figure 3 a is a schematic diagram of the moisture absorption rate of the macroporous hydrogels with photothermal conversion function in Examples 1-4 as a function of time. Figure 3 b is a schematic diagram of the moisture absorption rate of macroporous hydrogels with photothermal conversion function in Examples 1 and 5-6 as a function of time.

[0032] Figure 4 The absorption spectrum of the macroporous hydrogel with photothermal conversion function in Example 1 of Experiment 4 is shown in the wavelength range of 300-2500 nm.

[0033] Figure 5 The curves show the temperature changes of the macroporous hydrogels in Experimental Example 5, Example 1, Examples 7-8, and the comparative example as a function of xenon lamp (50W) irradiation time.

[0034] Figure 6 This is a schematic diagram of the photothermal water collection system used in the water collection test of Experiment Example 6 during operation; the reference numerals are as follows: 1-surface dish, 2-macroporous hydrogel, 3-outer wall, 4-sunlight, 5-liquid water;

[0035] Figure 7 This is a schematic diagram of the water collection efficiency changing over time in Experiment Example 6. Detailed Implementation

[0036] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0037] The organosilicon compounds used in the preparation of the macroporous hydrogels of Examples 1-8 and the comparative examples of this invention are shown in Formula IV;

[0038]

[0039] The preparation method of organosilicon compounds is as follows: 1,1,3,3-tetramethyldisiloxane and 3-aminopropyltrimethoxysilane in a molar ratio of 1:2 are placed in a round-bottom flask. Then, a Karst platinum catalyst (the mass of the platinum catalyst is 3‰ of the mass of 1,1,3,3-tetramethyldisiloxane and 3-aminopropyltrimethoxysilane) is added. The mixture is stirred at room temperature for 3 hours. When no bubbles are observed to form, it indicates that the reaction of 1,1,3,3-tetramethyldisiloxane and 3-aminopropyltrimethoxysilane is complete, yielding the organosilicon compound. The synthetic route for preparing organosilicon compounds is as follows:

[0040]

[0041] The macroporous hydrogels in Examples 1-6 of this invention use hydroxylated multi-walled carbon nanotubes with a diameter of 10-30 nm, a length of 10-30 μm, and a hydroxyl content of 2-4 wt% during preparation.

[0042] Example 1

[0043] The macroporous hydrogel with photothermal conversion function in this embodiment is prepared by a method including the following steps:

[0044] (1) Dissolve N,N'-methylenebisacrylamide in water to obtain an N,N'-methylenebisacrylamide solution, wherein the mass ratio of N,N'-methylenebisacrylamide to water is 0.001:20;

[0045] (2) The photothermal conversion material, lithium chloride, ammonium persulfate initiator and acrylamide were added to N,N'-methylenebisacrylamide solution and stirred evenly to obtain a mixture. Then, under stirring conditions, the organosilicon compound was added dropwise to the mixture and stirred evenly to obtain a mixture. The mixture was then poured into a mold and allowed to stand at room temperature for 30 minutes to obtain a macroporous hydrogel. Based on 100 parts by mass of N,N'-methylenebisacrylamide solution, the amount of lithium chloride was 40 parts by mass, the amount of ammonium persulfate initiator was 0.075 parts by mass, the amount of acrylamide was 25 parts by mass, the amount of organosilicon compound was 20 parts by mass, and the amount of photothermal conversion material was 0.1 parts by mass. The photothermal conversion material was hydroxylated multi-walled carbon nanotubes.

[0046] The macroporous hydrogel with photothermal conversion function in this embodiment is represented as CNT-SiPH-20-LiCl-40.

[0047] Example 2

[0048] The difference between the macroporous hydrogel with photothermal conversion function in this embodiment and the macroporous hydrogel with photothermal conversion function in Example 1 is that, in the preparation of the macroporous hydrogel with photothermal conversion function in this embodiment, the amount of lithium chloride is 40 parts by mass, the amount of ammonium persulfate initiator is 0.075 parts by mass, the amount of acrylamide is 25 parts by mass, the amount of organosilicon compound is 5 parts by mass, and the amount of photothermal conversion material is 0.1 parts by mass.

[0049] The macroporous hydrogel with photothermal conversion function in this embodiment is represented by CNT-SiPH-5-LiCl-40.

[0050] Example 3

[0051] The difference between the macroporous hydrogel with photothermal conversion function in this embodiment and the macroporous hydrogel with photothermal conversion function in Example 1 is only that, in the preparation of the macroporous hydrogel with photothermal conversion function in this embodiment, the amount of lithium chloride is 40 parts by mass, the amount of ammonium persulfate initiator is 0.075 parts by mass, the amount of acrylamide is 25 parts by mass, the amount of organosilicon compound is 10 parts by mass, and the amount of photothermal conversion material is 0.1 parts by mass.

[0052] The macroporous hydrogel with photothermal conversion function in this embodiment is represented as CNT-SiPH-10-LiCl-40.

[0053] Example 4

[0054] The difference between the macroporous hydrogel with photothermal conversion function in this embodiment and the macroporous hydrogel with photothermal conversion function in Example 1 is only that, in the preparation of the macroporous hydrogel with photothermal conversion function in this embodiment, the amount of lithium chloride is 40 parts by mass, the amount of ammonium persulfate initiator is 0.075 parts by mass, the amount of acrylamide is 25 parts by mass, the amount of organosilicon compound is 15 parts by mass, and the amount of photothermal conversion material is 0.1 parts by mass.

[0055] The macroporous hydrogel with photothermal conversion function in this embodiment is represented by CNT-SiPH-15-LiCl-40.

[0056] Example 5

[0057] The difference between the macroporous hydrogel with photothermal conversion function in this embodiment and the macroporous hydrogel with photothermal conversion function in Example 1 is only that, in the preparation of the macroporous hydrogel with photothermal conversion function in this embodiment, the amount of lithium chloride is 20 parts by mass, the amount of ammonium persulfate initiator is 0.075 parts by mass, the amount of acrylamide is 25 parts by mass, the amount of organosilicon compound is 20 parts by mass, and the amount of photothermal conversion material is 0.1 parts by mass.

[0058] The macroporous hydrogel with photothermal conversion function in this embodiment is represented as CNT-SiPH-20-LiCl-20.

[0059] Example 6

[0060] The difference between the macroporous hydrogel with photothermal conversion function in this embodiment and the macroporous hydrogel with photothermal conversion function in Example 1 is that, in the preparation of the macroporous hydrogel in this embodiment, based on 100 parts by mass of N,N'-methylenebisacrylamide solution, the amount of lithium chloride is 60 parts by mass, the amount of ammonium persulfate initiator is 0.075 parts by mass, the amount of acrylamide is 25 parts by mass, the amount of organosilicon compound is 10 parts by mass, and the amount of photothermal conversion material is 0.1 parts by mass.

[0061] The macroporous hydrogel with photothermal conversion function in this embodiment is represented as CNT-SiPH-20-LiCl-60.

[0062] Example 7

[0063] The macroporous hydrogel with photothermal conversion function in this embodiment is prepared by a method including the following steps:

[0064] (1) Dissolve N,N'-methylenebisacrylamide in water to obtain an N,N'-methylenebisacrylamide solution, wherein the mass ratio of N,N'-methylenebisacrylamide to water is 0.001:20;

[0065] (2) The photothermal conversion material, lithium chloride, ammonium persulfate initiator and acrylamide were added to the N,N'-methylenebisacrylamide solution and stirred evenly to obtain a mixture. Then, under stirring conditions, the organosilicon compound was added dropwise to the mixture and stirred evenly to obtain a mixture. The mixture was then poured into a mold and allowed to stand at room temperature for 30 minutes to obtain a macroporous hydrogel. Based on 100 parts by mass of N,N'-methylenebisacrylamide solution, the amount of lithium chloride was 40 parts by mass, the amount of ammonium persulfate initiator was 0.075 parts by mass, the amount of acrylamide was 25 parts by mass, the amount of organosilicon compound was 20 parts by mass, and the amount of photothermal conversion material was 0.1 parts by mass. The photothermal conversion material was molybdenum disulfide.

[0066] The macroporous hydrogel with photothermal conversion function in this embodiment is represented by MoS2-SiPH-20-LiCl-40.

[0067] Example 8

[0068] The only difference between the macroporous hydrogel with photothermal conversion function in this embodiment and the macroporous hydrogel with photothermal conversion function in Example 7 is that the photothermal conversion material of the macroporous hydrogel in this embodiment is graphene oxide.

[0069] The macroporous hydrogel with photothermal conversion function in this embodiment is represented as rGO-SiPH-20-LiCl-40.

[0070] Comparative Example

[0071] The only difference between the macroporous hydrogel of this comparative example and the macroporous hydrogel with photothermal conversion function in Example 1 is that the amount of photothermal conversion material used in the preparation of the macroporous hydrogel of this comparative example is 0 parts.

[0072] The macroporous hydrogel with photothermal conversion function in this comparative example is represented by SiPH-20-LiCl-40.

[0073] Experimental Example 1

[0074] The macroporous hydrogel with photothermal conversion function in Example 1 was observed by the naked eye and by scanning electron microscopy, and the results are as follows: Figure 1 As shown. The results indicate that the CNT-SiPH-20-LiCl-40 hydrogel exhibits good foaming properties, with prominent pore structures and visible macroporous structures. The macroporous hydrogels with photothermal conversion function in Examples 2-8 have similar pore structures to the macroporous hydrogel with photothermal conversion function in Example 1.

[0075] Experiment Example 2

[0076] To evaluate the effect of the amount of organosilicon compound on the mechanical properties of the prepared macroporous hydrogels with photothermal conversion function, the tensile property variation curves of the macroporous hydrogels with photothermal conversion function in Examples 1-4 were tested according to the method specified in standard ISO 37:2011 "Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber". The results are as follows: Figure 2 As shown. The results indicate that the macroporous hydrogels with photothermal conversion function in Examples 1-4 have good mechanical properties.

[0077] When testing the tensile property change curves of the macroporous hydrogels with photothermal conversion function in Examples 5-8 according to the above method, the test results are similar to the test results of the tensile property change curves of the macroporous hydrogels with photothermal conversion function in Examples 1-4.

[0078] Experimental Example 3

[0079] To evaluate the effects of the amounts of organosilicon compounds and lithium chloride on the moisture absorption rate of the prepared macroporous hydrogels with photothermal conversion function, the macroporous hydrogels with photothermal conversion function from Examples 1-6 were first weighed, and the original mass of each macroporous hydrogel was recorded. Then, the macroporous hydrogels were placed in an environment with 90% relative humidity, and the mass change of each macroporous hydrogel at different times was recorded. The ratio of the increase in mass of the macroporous hydrogel at a certain time to its original mass is the moisture absorption rate, expressed in g / g. The moisture absorption rate of the macroporous hydrogels with photothermal conversion function from Examples 1-6 as a function of time is shown in the figure below. Figure 3 As shown in the figure. The results indicate that at 90% relative humidity, the moisture absorption rate of CNT-SiPH-20-LiCl-40 hydrogel reached 5 g / g, while that of CNT-SiPH-20-LiCl-60 hydrogel was 8 g / g, far exceeding the maximum critical moisture absorption rate of 2.0 g / g for general hydrogels. With the increase of organosilicon content, the internal small network structure of the hydrogel increased, resulting in a higher moisture absorption rate.

[0080] When testing the moisture absorption rate of the macroporous hydrogels with photothermal conversion function in Examples 7-8 according to the above method, the test results are similar to the moisture absorption rate test results of the macroporous hydrogels with photothermal conversion function in Examples 1-6.

[0081] Experiment Example 4

[0082] To evaluate the absorption effect of the macroporous hydrogel with photothermal conversion function in Example 1 at wavelengths of 500–2500 nm, the absorption spectrum of the macroporous hydrogel with photothermal conversion function in Example 1 at wavelengths of 300–2500 nm was tested using a UV-Vis-NIR analyzer (Lambda 750s, Perkin Elmer). The results are as follows: Figure 4 As shown. The results show that the macroporous hydrogel of Example 1 has an absorption rate of nearly 100% for visible light, and its light transmittance is extremely low within this range. Therefore, the macroporous hydrogel has an excellent ability to absorb sunlight.

[0083] When the absorption spectra of the macroporous hydrogels with photothermal conversion function in Examples 2-8 were tested in the wavelength range of 300-2500 nm according to the above method, the test results were consistent with the test results of the absorption spectra of the macroporous hydrogels with photothermal conversion function in Example 1 in the wavelength range of 300-2500 nm.

[0084] Experimental Example 5

[0085] To evaluate the temperature changes of water, macroporous hydrogels with photothermal conversion function in Examples 1-8, and the comparative example under light irradiation, the temperature change curves of water, macroporous hydrogels with photothermal conversion function in Examples 1-8, and the comparative example as a function of xenon lamp (50W power) irradiation time were tested. The test results of the temperature change curves of macroporous hydrogels with photothermal conversion function in Examples 1, 7-8, and the comparative example as a function of xenon lamp (50W power) irradiation time are shown below. Figure 5 As shown in the figure, the CNT-SiPH-20-LiCl-40 hydrogel increased from an initial temperature of 23.1℃ to 36.8℃ after irradiation under a xenon lamp for 22 minutes, indicating that the hydrogel heats up quickly after absorbing sunlight and has good efficiency in converting light energy into heat energy. The temperature change curves of CNT-SiPH-20-LiCl-40 hydrogel, SiPH-20-LiCl-40 hydrogel, and water over xenon lamp irradiation time show that the temperature rise rate of CNT-SiPH-20-LiCl-40 hydrogel is faster, while the temperature rise rates of SiPH-20-LiCl-40 hydrogel and water are extremely slow. This indicates that the addition of CNTs significantly accelerates the heating rate of the hydrogel, thus exhibiting excellent photothermal conversion function. In addition, the temperature change curves of the macroporous hydrogels with photothermal conversion function in Examples 2-6 as a function of xenon lamp (power of 50W) irradiation time are similar to those of the macroporous hydrogels with photothermal conversion function in Example 1 as a function of xenon lamp (power of 50W) irradiation time.

[0086] After being irradiated under a xenon lamp for 60 minutes, the temperatures of MoS2-SiPH-20-LiCl-40 and rGO-SiPH-20-LiCl-40 hydrogels increased from the initial 23.1℃ and 33℃ to 43.2℃ and 45℃, respectively. This indicates that these two hydrogels heat up quickly after absorbing sunlight, have good efficiency in converting light energy into heat energy, and possess excellent photothermal conversion capabilities.

[0087] Experimental Example 6

[0088] To evaluate the water collection performance of the macroporous hydrogel with photothermal conversion function in Example 1 as a water collection material, a water collection test was conducted on the macroporous hydrogel with photothermal conversion function in Example 1. A schematic diagram of the photothermal water collection system used in the water collection test during operation is shown below. Figure 6 As shown, the macroporous hydrogel 2 is first placed in the petri dish 1 and then placed in humid air to allow the macroporous hydrogel 2 to adsorb water vapor from the air. Then, the macroporous hydrogel 2 after adsorbing water vapor and the petri dish 1 containing the macroporous hydrogel 2 are placed together in the photothermal water collection device. Under the irradiation of sunlight 4, the macroporous hydrogel 2 inside the photothermal water collection device converts the absorbed light energy into heat. The water adsorbed inside the macroporous hydrogel 2 turns into gas after being heated and escapes from the inside of the macroporous hydrogel. The escaped water vapor comes into contact with the outer wall 3 of the photothermal water collection device and condenses to form liquid water 5. The liquid water 5 collects in the water collection groove, completing the conversion and collection of water.

[0089] The curve showing the change in water collection efficiency over time after placing the macroporous hydrogel 2 (after adsorbing water vapor) in a photothermal water collection device at room temperature (30℃) is shown below. Figure 7 As shown, the water collection efficiency is equal to the ratio of the mass of water collected at a certain time to the mass of macroporous hydrogel 2. The results show that, under high outdoor temperatures, the macroporous hydrogel of Example 1, when exposed to sunlight for 9 hours, achieves a maximum water collection efficiency of 1.81 g / g.

[0090] When testing the water collection efficiency of the macroporous hydrogels with photothermal conversion function in Examples 2-8 according to the above method, the test results are similar to the test results of the water collection efficiency of the macroporous hydrogel with photothermal conversion function in Example 1.

Claims

1. A macroporous hydrogel with photothermal conversion function, characterized in that, The method comprises the following steps: mixing an organosilicon compound, a water-soluble polymeric monomer, a photothermal conversion material, an initiator, and water; simultaneously, the water-soluble polymeric monomer polymerizes and crosslinks, releasing gas to form a foaming system, thereby obtaining a macroporous hydrogel with photothermal conversion function; the organosilicon compound has the structure shown in Formula I: In Equation I, R1, R2, R3, R 10 R 11 and R 12 Each of the components is independently selected from C1-C5 alkyl groups; R4 and R5 are independently selected from C3-C6 alkylene groups; R6, R7, R8 and R9 are independently selected from methyl, ethyl or propyl groups; the mass ratio of the water-soluble polymeric monomer to the organosilicon compound is 5:(1-4); a catalyst is also added during the mixing process, the catalyst is selected from one or any combination of lithium chloride, sodium chloride, and calcium chloride, the mass ratio of the water-soluble polymeric monomer to the catalyst is 5:(4-12); the mass ratio of the water-soluble polymeric monomer to the photothermal conversion material is 25:(0.03-0.1).

2. The macroporous hydrogel with photothermal conversion function as described in claim 1, characterized in that, In Equation I, R1, R2, R3, R 10 R 11 and R 12 All are methyl; R4 and R5 are both propylene; R6, R7, R8 and R9 are all methyl.

3. The macroporous hydrogel with photothermal conversion function as described in claim 1, characterized in that, The photothermal conversion material is selected from one or any combination of carbon nanotubes, graphene oxide, MXene, and molybdenum disulfide.

4. The macroporous hydrogel with photothermal conversion function as described in claim 1, characterized in that, The initiator is a persulfate initiator.

5. The macroporous hydrogel with photothermal conversion function as described in claim 4, characterized in that, The persulfate initiator is ammonium persulfate; the mass ratio of the water-soluble polymerizable monomer to the persulfate initiator is 5:(0.005~0.015).

6. The macroporous hydrogel with photothermal conversion function as described in any one of claims 1-5, characterized in that, The water-soluble polymeric monomer includes a first water-soluble polymeric monomer and a second water-soluble polymeric monomer. The first water-soluble polymeric monomer has one and only one olefinic unsaturated double bond, and the second water-soluble polymeric monomer has at least one or more olefinic unsaturated double bonds.

7. The macroporous hydrogel with photothermal conversion function as described in claim 6, characterized in that, The first water-soluble polymeric monomer is selected from one or any combination of acrylamide, methacrylamide, acrylic acid, N-isopropylacrylamide, and N,N-dimethylacrylamide; the second water-soluble polymeric monomer is N,N'-methylenebisacrylamide.

8. The macroporous hydrogel with photothermal conversion function as described in claim 6, characterized in that, The mass ratio of water, the first water-soluble polymeric monomer, and the second water-soluble polymeric monomer is 20:5:(0.01 to 0.001).

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