A structure-controllable and response performance-adjustable hydrogel and a preparation method thereof

Abstract

This invention discloses a hydrogel with controllable structure and tunable response performance, and its preparation method. The method includes: adding hydrogel material monomers and an initiator to an aqueous dispersion of lithium diatomite to synthesize a basic hydrogel system; soaking the basic hydrogel system in water, and after removing unreacted monomers, crosslinking agents, and initiators, drying and grinding to obtain microgel powder; adding a swelling agent to the microgel powder and then sealing and solidifying to obtain the hydrogel material. This invention can rapidly synthesize hydrogel materials with controllable structure and effective response to multiple stimuli. Its process is simple, safe, and low-cost, making it suitable for mass production.

Description

Technical Field

[0001] This invention relates to the technical field of hydrogel materials. Background Technology

[0002] Hydrogels are three-dimensional networks composed of hydrophilic polymers and containing a large amount of water. They can swell in water but do not dissolve, exhibiting some properties of both solids and liquids. Research on hydrogels has expanded from basic scientific research to fields such as tissue engineering, drug delivery, biological research, wearable electronic devices, and soft robotics. Today, hydrogels have become one of the most widely studied materials in interdisciplinary fields. The ever-expanding application areas also place higher demands on the diversification of hydrogel structures, the controllability of responsive stimuli, the simplification of preparation processes, and safety.

[0003] Hydrogels synthesized by crosslinking hydrophilic polymers or polymerizing water-soluble monomers containing crosslinking agents typically possess amorphous and isotropic structures, which limits their applications to some extent. In recent years, with the development of microfluidic technology, 3D printing technology, and other technologies, some breakthroughs have been made in the designability of hydrogel structures and the controllability of their responsive behavior. However, the large-scale production of hydrogels that meet application requirements using simple and safe synthesis methods remains a significant technical challenge. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a method for rapidly synthesizing hydrogels with controllable structures that can effectively respond to multiple stimuli, as well as the resulting hydrogel material. The method is simple, safe, low-cost, and suitable for mass production.

[0005] The technical solution of the present invention is as follows:

[0006] A method for preparing hydrogel materials with controllable structure and tunable response properties, comprising:

[0007] Aqueous dispersion of lithium diatomite was obtained;

[0008] A basic hydrogel system is synthesized by adding hydrogel material monomers and initiators to the aqueous dispersion.

[0009] The basic hydrogel system is soaked in water, and then the unreacted monomers, crosslinking agents and initiators are removed. The system is then dried and ground to screen out the micron-sized gel powder, i.e. microgel powder.

[0010] After adding a swelling agent to the microgel powder, the mixture is sealed and cured to obtain the hydrogel material with controllable structure and adjustable response performance.

[0011] According to some preferred embodiments of the present invention, the swelling agent is selected from ethanol and / or water.

[0012] According to some preferred embodiments of the present invention, the initiator is selected from a mixed solution of 1-hydroxycyclohexylphenyl ketone and benzophenone.

[0013] According to some preferred embodiments of the present invention, the mass fraction of lithium diatomite in the lithium diatomite aqueous dispersion is 15-115 mg / ml.

[0014] According to some preferred embodiments of the present invention, in the mixed solution of 1-hydroxycyclohexylphenyl ketone and benzophenone, the mass ratio of 1-hydroxycyclohexylphenyl ketone to benzophenone is 1:1.

[0015] According to some preferred embodiments of the present invention, the solvent of the mixed solution of 1-hydroxycyclohexylphenyl ketone and benzophenone is selected from ethanol.

[0016] According to some preferred embodiments of the present invention, the mass of the 1-hydroxycyclohexylphenyl ketone and benzophenone added is 0.2-2% of the mass of the monomer.

[0017] According to some preferred embodiments of the present invention, the preparation method specifically includes:

[0018] N-isopropylacrylamide and / or acrylamide were added to the aqueous dispersion of lithium diatomite until it dissolved. Then, a mixed solution of 1-hydroxycyclohexylphenyl ketone and benzophenone was added. The resulting mixture was sealed and synthesized under ultraviolet light irradiation to obtain the first basic hydrogel system.

[0019] More preferably, the concentration of acrylamide and / or N-isopropylacrylamide in the aqueous dispersion of lithium diatomite is 0.9 to 1.1 mol / L; and / or the molar ratio of acrylamide to N-isopropylacrylamide is 0:1 to 3:7.

[0020] According to some preferred embodiments of the present invention, the preparation method specifically includes:

[0021] An aqueous dispersion of sheet-like graphene oxide was obtained;

[0022] The lithium diatomite was added to the aqueous dispersion of the graphene oxide to obtain an aqueous dispersion of the lithium diatomite containing graphene oxide.

[0023] N-Isopropylacrylamide was added to the aqueous dispersion of lithium diatomite until it dissolved, and then a mixed solution of 1-hydroxycyclohexylphenyl ketone and benzophenone was added. The resulting mixture was then sealed and synthesized under ultraviolet light to obtain the second basic hydrogel system.

[0024] More preferably, the concentration of N-isopropylacrylamide in the lithium diatomaceous earth aqueous dispersion containing graphene oxide is 0.9–1.1 mol / L, and / or the concentration of graphene oxide in the graphene oxide aqueous dispersion is 0–1 mg / mL.

[0025] According to some preferred embodiments of the present invention, the preparation method specifically includes:

[0026] Aqueous dispersion of Fe3O4 nanoparticles was obtained;

[0027] N-isopropylacrylamide was added to the aqueous dispersion of lithium diatomite until it dissolved, and then the aqueous dispersion of Fe3O4 nanoparticles was added until it was mixed evenly. Then the mixed solution of 1-hydroxycyclohexylphenyl ketone and benzophenone was added. The resulting mixed system was sealed and synthesized under ultraviolet light irradiation to obtain the third basic hydrogel system.

[0028] More preferably, the concentration of N-isopropylacrylamide in the aqueous dispersion of lithium diatomite is 0.9–1.1 mol / L; and / or the concentration of Fe3O4 nanoparticles in the aqueous dispersion of Fe3O4 nanoparticles is 0–10 mg / mL.

[0029] According to some preferred embodiments of the present invention, the base hydrogel system includes one or more of the first base hydrogel system, the second base hydrogel system, and the third base hydrogel system.

[0030] The present invention further provides a hydrogel material with controllable structure and tunable response performance prepared according to any of the above preparation methods. The material has a dense layered stacked structure and a porous structure after adding deionized water to form a hydrogel. The pore structure can be controlled according to the size of the added microgel powder.

[0031] The preparation method of this invention allows the obtained basic hydrogel system to fully swell in deionized water, causing the polymer chains in the gel network to be in an elongated and extended state. When the gel breaks into small pieces, the long polymer chains inside break into short polymer chains, causing the large gel to decompose into multiple gel units with a uniform internal network structure and multiple short polymer chains on the surface. After the gel is removed from the deionized water and dried, as the water inside the gel unit vaporizes and is carried away by the surrounding unsaturated humid air, the wet gel loses water and becomes a dry gel, with a significant reduction in volume. The internal porous structure also collapses and curls together due to the loss of water in the polymer chains, forming a dense layered stacked structure, causing the polymer chains to be in a contracted state. Finally, the dry gel is placed in a sealed container, and an appropriate volume of liquid is added. Due to the limited swelling volume, after the dry gel absorbs the liquid and swells, the short polymer chains on the surface easily extend into the interior of the adjacent swollen gel. The -CONH(R) groups carried by the dry gel easily form hydrogen bonds with the Si-OH and Si-O-Si groups on the surface of the adjacent lithium diatomite sheet, forming a stable and new cross-linked structure.

[0032] The present invention has the following beneficial effects:

[0033] (1) This invention provides a method for rapidly synthesizing multi-stimulus responsive hydrogels, which can be gelled within minutes after the prepared microgel is mixed with an appropriate amount of liquid.

[0034] (2) The method provided by the present invention is applicable to the formation of gels by mixing the same or different types of microgels with an appropriate amount of liquid.

[0035] (3) The structure and response properties of the multi-stimulus responsive hydrogel prepared by the present invention can be adjusted as needed.

[0036] (4) The preparation process provided by the present invention is simple, safe, low-cost and suitable for mass production. Attached Figure Description

[0037] Figure 1 The image shown is a scanning electron microscope image of the microgel powder in Example 2, where the right image is a partial magnification of the left image.

[0038] Figure 2 This is a scanning electron microscope image of the gel product formed by mixing microgel powder and deionized water in Example 2.

[0039] Figure 3 This is a characterization diagram of the temperature response characteristics of the gel product obtained in Example 2.

[0040] Figure 4 The image shown is a scanning electron microscope image of the microgel powder obtained in Example 3, where the right image is a partial magnification of the left image.

[0041] Figure 5This is a scanning electron microscope image of the gel product formed by mixing microgel powder and deionized water in Example 3.

[0042] Figure 6 This is a characterization diagram of the temperature response characteristics of the gel product obtained in Example 3.

[0043] Figure 7 This is a scanning electron microscope image of the gel product obtained from the second gel in Example 4.

[0044] Figure 8 This is a characterization diagram of the temperature response characteristics of the gel product obtained in Example 4.

[0045] Figure 9 This is a characterization diagram of the near-infrared light response properties of the gel product obtained in Example 4.

[0046] Figure 10 This is a scanning electron microscope image of the gel product obtained from the third gel in Example 5.

[0047] Figure 11 This is a characterization diagram of the temperature response characteristics of the gel product obtained in Example 5.

[0048] Figure 12 This is a characterization diagram of the near-infrared light response properties of the gel product obtained in Example 5.

[0049] Figure 13 This is a characterization diagram of the magnetic field response characteristics of the gel product obtained in Example 5.

[0050] Figure 14 The image shows scanning electron microscope (SEM) images of the gel products obtained from the first to third gels in Example 6. Detailed Implementation

[0051] The present invention will now be described in detail with reference to embodiments and accompanying drawings. However, it should be understood that the embodiments and drawings are for illustrative purposes only and do not constitute any limitation on the scope of protection of the present invention. All reasonable modifications and combinations included within the inventive spirit of the present invention fall within the scope of protection of the present invention.

[0052] According to the technical solution of the present invention, some specific methods for preparing hydrogels with controllable structure and tunable response properties include:

[0053] (1) Synthesize a nanocomposite hydrogel with temperature-responsive properties;

[0054] (2) Synthesize nanocomposite hydrogels with dual stimulation responses of temperature and near-infrared light;

[0055] (3) Synthesize nanocomposite hydrogels with triple stimulation responses of temperature, near-infrared light and magnetic field;

[0056] (4) The nanocomposite hydrogels obtained in steps (1), (2) and (3) are replaced with water and allowed to stand. After removing the unreacted monomers, crosslinking agents and initiators, they are crushed and then placed in the environment to dry. After they are completely dry, they are ground into powder and the microgel powder with a size in the micrometer range is selected.

[0057] (5) Add swelling agent to the obtained microgel powder, seal and let stand for a period of time. After solidification, the hydrogel with controllable structure and adjustable response performance is formed.

[0058] Step (1) may further include:

[0059] A certain amount of lithium diatomite was added to deionized water and dispersed to obtain a clear and transparent dispersion.

[0060] Monomers N-isopropylacrylamide (NIPAM) and acrylamide (AM) were added to the dispersion until the monomers were completely dissolved. Finally, a mixed solution prepared by dissolving equal amounts of photoinitiators 1-hydroxycyclohexylphenyl ketone and benzophenone in ethanol was added until the resulting mixture was evenly dispersed. The mixture was then injected into a transparent mold and sealed. The temperature-responsive nanocomposite hydrogel was synthesized by irradiation under ultraviolet light (wavelength such as 365 nm).

[0061] Step (2) may further include:

[0062] To obtain dry, sheet-like graphene oxide;

[0063] The obtained graphene oxide was added to deionized water and dispersed by ultrasonic oscillation. Then, lithium diatomaceous earth was added and stirred vigorously until a clear and transparent mixed dispersion was formed.

[0064] The monomer NIPAM is added to the mixed dispersion until it is completely dissolved. Finally, a mixed solution prepared by dissolving equal amounts of photoinitiators 1-hydroxycyclohexylphenyl ketone and benzophenone in ethanol is added until the resulting mixed system is evenly dispersed. The mixture is then injected into a transparent mold and sealed. The nanocomposite hydrogel with dual stimulation response of temperature and near-infrared light can be synthesized by irradiation under ultraviolet light (wavelength such as 365nm).

[0065] The dried sheet-like graphene oxide can be further obtained by referring to existing technologies, such as preparing a dispersion of graphene oxide according to the Hummers method (Journal of the American Chemical Society, 1958, 80, 1339-1339), and drying the dispersion to obtain sheet-like graphene oxide.

[0066] Step (3) may further include:

[0067] Aqueous dispersion of Fe3O4 nanoparticles was obtained;

[0068] Lithium diatomite was dispersed in deionized water to obtain a clear and transparent dispersion.

[0069] Monomer NIPAM is added to the dispersion and stirred until it is completely dissolved. Then, a certain amount of the obtained Fe3O4 nanoparticle aqueous dispersion is added under continuous shaking and stirring. After it is mixed evenly, a mixed solution prepared by dissolving equal amounts of photoinitiator 1-hydroxycyclohexylphenyl ketone and benzophenone in ethanol is added. After the resulting mixed system is evenly dispersed, it is injected into a transparent mold and sealed. The nanocomposite hydrogel with triple stimulation response of temperature, near-infrared light and magnetic field can be synthesized by irradiation under ultraviolet light (wavelength such as 365nm).

[0070] The aqueous dispersion of Fe3O4 nanoparticles can be further obtained by referring to existing technologies, such as the method in Soft Matter, 2012, 8, 3295-3299.

[0071] The swelling agent mentioned in step (5) can be selected from deionized water and / or ethanol.

[0072] Example 1

[0073] (1) Add 10 mL of deionized water to a 25 mL beaker, add 0.15–1.15 g of lithium diatomite Laponite XLS, stir vigorously until a clear and transparent dispersion is obtained, then add 0.01 mol of monomer N-isopropylacrylamide (NIPAM) and acrylamide (AM), wherein the molar ratio of N-isopropylacrylamide (NIPAM) to acrylamide (AM) is 1:0–7:3, to the extent that the monomers are completely dissolved, and finally add 100 μL of Irg.500 solution prepared by dissolving equal amounts of photoinitiator 184 (1-hydroxycyclohexylphenyl ketone) and benzophenone in ethanol, stir to disperse evenly, inject the resulting solution into a transparent mold and seal it, and irradiate with ultraviolet light of wavelength 365 nm for 5 min to synthesize the first gel.

[0074] (2) First, a dispersion of graphene oxide was prepared according to the Hummers method. After drying, sheet-like graphene oxide was obtained. Then, 10 mL of deionized water and 5-15 mg of graphene oxide sheets were added to a 25 mL beaker. The dispersion was ultrasonically dispersed for 0.5 h. 0.15-1.15 g of lithium diatomite Laponite XLS was added and stirred vigorously until the graphene oxide and lithium diatomite were evenly dispersed in water and formed a clear and transparent dispersion. Then, 0.01 mol of monomer NIPAM was added, until the monomer was completely dissolved. Finally, 100 μL of Irg.500 solution prepared by dissolving equal amounts of photoinitiator 184 (1-hydroxycyclohexylphenyl ketone) and benzophenone in ethanol was added. After stirring to disperse the solution evenly, the resulting solution was injected into a transparent mold and sealed. The solution was irradiated with ultraviolet light at a wavelength of 365 nm for 5 min to synthesize the second gel.

[0075] (3) Add 9 mL of deionized water and 0.15–1.15 g of lithium diatomaceous earth to a 25 mL beaker, stir vigorously to disperse the lithium diatomaceous earth evenly and form a clear and transparent dispersion; then add 0.01 mol of monomer NIPAM and continue stirring until the monomer is completely dissolved; add 1 mL of aqueous dispersion of Fe3O4 nanoparticles under continuous shaking and stirring, wherein the concentration of Fe3O4 nanoparticles in the aqueous dispersion of Fe3O4 nanoparticles is 5–15 mg / mL, and after it is mixed evenly, add 100 μL of Irg.500 solution prepared by dissolving equal amounts of photoinitiator 184 (1-hydroxycyclohexylphenyl ketone) and benzophenone in ethanol, stir to disperse evenly, and then inject the resulting solution into a transparent mold and seal it. Irradiate with ultraviolet light of wavelength 365 nm for 5 min to synthesize the third gel.

[0076] (4) Change the water in the gel synthesized in steps (1), (2) and (3) for one week to remove unreacted monomers, crosslinking agents and initiators. After crushing, place it in an environment of about 25°C and relative humidity of 50-75% to dry. After it is completely dry, grind it into powder and sieve it with a stainless steel sieve to separate the microgel powder of the required size.

[0077] (5) Weigh the microgel powder prepared in step (4) and place it in a container. Add an appropriate amount of liquid deionized water or ethanol, seal it, and let it stand for a period of time until it solidifies to form the product gel.

[0078] Example 2

[0079] (1) Add 10 mL of deionized water to a 25 mL beaker. Add 0.0020 g of dye for easy observation. After the dye is completely dissolved, add 0.3808 g of lithium diatomite XLS. Stir vigorously for 4 h to disperse the lithium diatomite evenly. After obtaining a clear and transparent dispersion, place the beaker in an ice bath and add 0.01 mol of monomer NIPAM. Continue stirring for 2 h and then add 100 μL of Irg.500 solution, the same as in Example 1. Stir quickly and evenly, then transfer to a transparent polytetrafluoroethylene tube and seal it. Irradiate with ultraviolet light in an ice bath for 5 min and then take it out to obtain the first gel.

[0080] (2) Change the water in the gel synthesized in step (1) for one week to remove unreacted monomers, crosslinking agents and initiators. Then, chop it with a blade and dry it in an environment with a suitable temperature (around 25°C) and relative humidity of 50-75%. After the gel is completely dry, transfer it to a mortar and grind it into powder. Use a stainless steel sieve to separate the microgel powder of the required size. The size of the obtained microgel powder is not uniform, but all are below 100μm. The first gel product is obtained.

[0081] The microstructure of the first gel product was characterized, and its scanning electron microscope results are shown in the attached figure. Figure 1 As shown, the resulting product has a dense, layered stacked structure.

[0082] (3) Weigh an appropriate amount of the microgel powder prepared in step (2) and place it in a container. Then add deionized water. The mass ratio of microgel powder to deionized water should be controlled at 0.1 to 0.2. After sealing, let it stand for several minutes to form a gel. Characterize the microstructure of the obtained gel. Its scanning electron microscope is shown in the attached figure. Figure 2 As shown, the formed gel has a stable porous structure.

[0083] The thermosensitive response behavior of the gel obtained in step (3) was tested. The characterization method was as follows: the quartz cell containing the layered first gel was sealed with a coverslip and placed on a hot stage. The temperature of the quartz cell was controlled by the hot stage temperature. The temperature was measured in real time by a thermal imager. The volume change of the sample was recorded in real time by a camera on the upper part of the sample cell. The volume-temperature-time curve of the first gel during the heating process was obtained. The results are shown in the attached figure. Figure 3 As shown, it can be seen that during the heating process from 26℃ to 55℃, the gel undergoes significant volume shrinkage, shrinking to 29% of its initial size, and the internal structure remains stable with no breakage observed.

[0084] Example 3

[0085] (1) Add 10 mL of deionized water to a 25 mL beaker. Add 0.0020 g of dye for easy observation. After the dye is completely dissolved, add 1.1424 g of lithium diatomite XLS. Stir vigorously for 4 h to disperse the lithium diatomite evenly. After obtaining a clear and transparent dispersion, place the beaker in an ice bath and add 0.01 mol of monomer NIPAM. Continue stirring for 2 h and then add 100 μL of Irg.500 solution, the same as in Example 1. Stir quickly and evenly, then transfer to a transparent polytetrafluoroethylene tube and seal it. Irradiate with ultraviolet light in an ice bath for 5 min and then remove it to obtain the first gel.

[0086] (2) Change the water in the gel synthesized in step (1) for one week to remove unreacted monomers, crosslinking agents and initiators. Then, chop it with a blade and dry it in an environment with a suitable temperature (around 25°C) and relative humidity of 50-75%. After the gel is completely dry, transfer it to a mortar and grind it into powder. Use a stainless steel sieve to separate the microgel powder of the required size. The size of the obtained microgel powder is not uniform, but all are below 100μm. The first gel product is obtained.

[0087] The microstructure of the first gel product was characterized, and its scanning electron microscope results are shown in the attached figure. Figure 4 As shown, the resulting product has a dense, layered stacked structure.

[0088] (3) Weigh an appropriate amount of the microgel powder prepared in step (2) and place it in a container. Then add deionized water. The mass ratio of microgel powder to deionized water should be controlled at 0.1 to 0.2. After sealing, let it stand for several minutes to form a gel. Characterize the microstructure of the obtained gel. Its scanning electron microscope is shown in the attached figure. Figure 5 As shown, the formed gel has a stable porous structure.

[0089] The temperature-sensitive response behavior of the gel obtained in step (3) was tested. The characterization method was as follows: the quartz tank containing the layered first gel was sealed with a coverslip and placed on a hot stage. The temperature of the quartz tank was controlled by the temperature of the hot stage. The temperature was measured in real time by a thermal imager. The volume change of the sample was recorded in real time by a camera on the upper part of the sample tank. The volume-temperature-time change curve of the first gel during the heating process was obtained. The results are shown in the attached figure. Figure 6 As shown, it can be seen that during the heating process from 26℃ to 55℃, the gel undergoes significant volume shrinkage, shrinking to 50% of its initial size, and the internal structure remains stable with no breakage observed.

[0090] Example 4

[0091] (1) Add 10 mL of deionized water and 10 mg of graphene oxide sheets to a 25 mL beaker, and disperse under sonication for 0.5 h. After it is completely dissolved, add 0.3808 g of lithium diatomite XLS and stir vigorously for 4 h to disperse the lithium diatomite evenly. After obtaining a clear and transparent dispersion, place the beaker in an ice bath, add 0.01 mol of monomer NIPAM, continue stirring for 2 h, and then add 100 μL of Irg.500 solution, which is the same as in Example 1. Stir quickly and evenly, transfer to a transparent polytetrafluoroethylene tube and seal it. After irradiating with ultraviolet light in an ice bath for 5 min, take it out to obtain the second gel.

[0092] (2) Change the water in the gel synthesized in step (1) for one week to remove the unreacted monomers, crosslinking agents and initiators. Then, chop it with a blade and dry it in an environment with a suitable temperature (around 25°C) and relative humidity of 50-75%. After the gel is completely dry, transfer it to a mortar and grind it into powder. Use a stainless steel sieve to separate the microgel powder of the required size. The size of the obtained microgel powder is not uniform, but all are below 100μm. The second gel product is obtained.

[0093] (3) Weigh an appropriate amount of the microgel powder prepared in step (2) and place it in a container. Then add deionized water. The mass ratio of microgel powder to deionized water should be controlled at 0.1 to 0.2. After sealing, let it stand for several minutes to form a gel. Characterize the microstructure of the obtained gel. Its scanning electron microscope is shown in the attached figure. Figure 7 As shown, the formed gel has a stable porous structure.

[0094] The temperature response characteristics of the obtained second gel product were characterized as follows: a quartz tank containing the layered second gel was sealed with a coverslip and placed on a hot stage. The temperature of the quartz tank was controlled by the hot stage temperature, and the temperature was measured in real time using a thermal imager. The volume change of the sample was recorded in real time using a camera above the sample tank. The volume-temperature-time curve of the second gel during the heating process was obtained, and the results are shown in the attached figure. Figure 8 As shown, it can be seen that during the heating process from 21℃ to 62℃, the gel undergoes significant volume shrinkage, shrinking to 36% of its initial size, and the internal structure remains stable with no breakage observed.

[0095] The near-infrared light response characteristics of the obtained second gel product were characterized as follows: The prepared layered second gel was placed in a quartz tank filled with deionized water and sealed with a coverslip. A laser system capable of emitting near-infrared light with a wavelength of 808 nm and a power of 2–5 W was installed 10–20 cm directly above the quartz tank. The light source was turned on, and the second gel was ensured to be within the near-infrared light irradiation range. The temperature was measured in real time using a thermal imager, and the sample volume change was recorded in real time using a camera above the sample tank. The temperature-volume-time curve of the second gel during the light irradiation process was obtained, and the results are shown in the attached figure. Figure 9 As shown, within 10 minutes of light exposure, the temperature of the second gel increased from 25°C to 57°C, the volume shrank to 39% of its initial size, and the structure remained stable with no breakage observed.

[0096] Example 5

[0097] (1) Add 9 mL of deionized water and 0.3808 g of lithium diatomite XLS to a 25 mL beaker. Stir vigorously for 4 h to disperse the lithium diatomite evenly and obtain a clear and transparent dispersion. Then place the beaker in an ice bath, add 0.01 mol of monomer NIPAM, and continue stirring for 2 h. Then add 1 mL of aqueous dispersion of Fe3O4 nanoparticles under continuous shaking and stirring. After mixing evenly, add 100 μL of Irg.500 solution, the same as in Example 1. Stir quickly and evenly, then transfer to a transparent polytetrafluoroethylene tube and seal it. After irradiating with ultraviolet light in an ice bath for 5 min, take it out to obtain the third gel.

[0098] (2) Change the water in the gel synthesized in step (1) for one week to remove unreacted monomers, crosslinking agents and initiators. Then, chop it with a blade and dry it in an environment with a suitable temperature (around 25°C) and relative humidity of 50-75%. After the gel is completely dry, transfer it to a mortar and grind it into powder. Use a stainless steel sieve to separate the microgel powder of the required size. The size of the obtained microgel powder is not uniform, but all are below 100μm. The third gel product is obtained.

[0099] (3) Weigh an appropriate amount of the microgel powder prepared in step (2) and place it in a container. Then add deionized water. The mass ratio of microgel powder to deionized water should be controlled at 0.1 to 0.2. After sealing, let it stand for several minutes to form a gel. Characterize the microstructure of the obtained gel. Its scanning electron microscope is shown in the attached figure. Figure 10 As shown in the figure, the formed gel has a porous structure.

[0100] The temperature response characteristics of the obtained third gel product were characterized as follows: a quartz tank containing the layered third gel was sealed with a coverslip and placed on a hot stage. The temperature of the quartz tank was controlled by the hot stage temperature, and the temperature was measured in real time using a thermal imager. The volume change of the sample was recorded in real time using a camera above the sample tank. The volume-temperature-time curve of the third gel during the heating process was obtained, and the results are attached. Figure 11 As shown, it can be seen that during the heating process from 21℃ to 61℃, the gel undergoes significant volume shrinkage, shrinking to 17% of its initial size, and the internal structure remains stable with no breakage observed.

[0101] The obtained third gel product was characterized by its near-infrared light response properties. The method was as follows: the prepared layered third gel was placed in a quartz tank filled with deionized water and sealed with a coverslip. A laser system capable of emitting near-infrared light with a wavelength of 808 nm and a power of 2–5 W was installed 10–20 cm directly above the quartz tank. The light source was turned on, and the third gel was ensured to be within the irradiation range of the near-infrared light. The temperature was measured in real time using a thermal imager, and the sample volume change was recorded in real time using a camera above the sample tank. The temperature-volume-time curve of the third gel during the light irradiation process was obtained, and the results are attached. Figure 12 As shown, within 10 minutes of light exposure, the temperature of the second gel increased from 24°C to 44°C, the volume shrank to 13% of its initial size, and the structure remained stable with no breakage observed.

[0102] The magnetic field response characteristics of the obtained third gel product were characterized by placing the third gel in a quartz tank containing deionized water and slowly contacting the gel with a magnet. The results are shown in the attached figure. Figure 13 As shown, it can be seen that the gel is indeed magnetic, and can be attracted to a magnet and follow its movement.

[0103] Example 6

[0104] Weigh appropriate amounts of the microgel powder prepared in Examples 2, 3, and 5 and place them in a container. Then add deionized water, controlling the mass ratio of microgel powder to deionized water to be 0.1–0.2. After sealing, let it stand for several minutes to form a composite gel. Characterize the microstructure of the obtained gel using scanning electron microscopy, as shown in the attached figure. Figure 14 As shown, the formed gel has a porous structure. This indicates that the present invention allows the microgel powder to be directly mixed with a liquid and then stabilized into a gel in a short time, and the process is safe and environmentally friendly.

[0105] The above embodiments are merely preferred embodiments of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing hydrogel materials with controllable structure and tunable response properties, characterized in that, It includes: Aqueous dispersion of lithium diatomite was obtained; A basic hydrogel system is synthesized by adding hydrogel material monomers and initiators to the aqueous dispersion. The basic hydrogel system is soaked in water to remove unreacted monomers, lithium diatomaceous earth, and initiators. The system is then dried and ground to screen out micron-sized gel powder, i.e., microgel powder. The drying process involves drying in an environment of 25°C and 50-75% relative humidity. After adding a swelling agent to the microgel powder, the mixture is sealed and cured to obtain the hydrogel material with controllable structure and adjustable response performance. The initiator is selected from a mixed solution of 1-hydroxycyclohexylphenyl ketone and benzophenone; the swelling agent is selected from water; and the hydrogel material monomer is selected from N-isopropylacrylamide and / or acrylamide.

2. The preparation method according to claim 1, characterized in that, in, The lithium diatomite aqueous dispersion has a lithium diatomite mass fraction of 15-115 mg / ml; and / or, in the mixed solution of 1-hydroxycyclohexylphenyl ketone and benzophenone, the mass ratio of 1-hydroxycyclohexylphenyl ketone to benzophenone is 1:1; and / or, the solvent of the mixed solution of 1-hydroxycyclohexylphenyl ketone and benzophenone is selected from ethanol; and / or, the added mass of 1-hydroxycyclohexylphenyl ketone and benzophenone is 0.2-2% of the mass of the monomer.

3. The preparation method according to claim 2, characterized in that, The synthesis of the basic hydrogel system includes: N-isopropylacrylamide and / or acrylamide were added to the aqueous dispersion of lithium diatomite until it dissolved. Then, a mixed solution of 1-hydroxycyclohexylphenyl ketone and benzophenone was added. The resulting mixture was sealed and synthesized under ultraviolet light to obtain the first basic hydrogel system.

4. The preparation method according to claim 3, characterized in that, in, The concentration of the acrylamide and / or the N-isopropylacrylamide in the aqueous dispersion of the lithium diatomite is 0.9 to 1.1 mol / L; and / or the molar ratio of the acrylamide to the N-isopropylacrylamide is 0:1 to 3:

7.

5. The preparation method according to claim 2, characterized in that, The synthesis of the basic hydrogel system includes: An aqueous dispersion of sheet-like graphene oxide was obtained; The lithium diatomite was added to the aqueous dispersion of the graphene oxide to obtain an aqueous dispersion of the lithium diatomite containing graphene oxide. N-Isopropylacrylamide was added to the aqueous dispersion of lithium diatomite until it dissolved. Then, a mixed solution of 1-hydroxycyclohexylphenyl ketone and benzophenone was added. The resulting mixture was sealed and synthesized under ultraviolet light to obtain the second basic hydrogel system.

6. The preparation method according to claim 5, characterized in that, in, The concentration of N-isopropylacrylamide in the lithium diatomaceous earth aqueous dispersion containing graphene oxide is 0.9–1.1 mol / L, and / or the concentration of graphene oxide in the graphene oxide aqueous dispersion is 0–1 mg / mL.

7. The preparation method according to claim 2, characterized in that, The synthesis of the basic hydrogel system includes: Aqueous dispersion of Fe3O4 nanoparticles was obtained; N-isopropylacrylamide was added to the aqueous dispersion of lithium diatomite until it dissolved, and then the aqueous dispersion of Fe3O4 nanoparticles was added until it was mixed evenly. Then the mixed solution of 1-hydroxycyclohexylphenyl ketone and benzophenone was added. The resulting mixed system was sealed and synthesized under ultraviolet light irradiation to obtain the third basic hydrogel system.

8. The preparation method according to claim 7, characterized in that, in, The concentration of N-isopropylacrylamide in the aqueous dispersion of lithium diatomite is 0.9–1.1 mol / L; and / or the concentration of Fe3O4 nanoparticles in the aqueous dispersion of Fe3O4 nanoparticles is 0–10 mg / mL.

9. The preparation method according to claim 1, characterized in that, The basic hydrogel system includes one or more of the first basic hydrogel system of claim 3, the second basic hydrogel system of claim 5, and the third basic hydrogel system of claim 7.

10. A hydrogel material with controllable structure and tunable response properties prepared by the preparation method according to any one of claims 1 to 9.

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