Liquid metal / mxene / sodium alginate / polyacrylamide composite hydrogel material and preparation method and application thereof

Abstract

The present application relates to a kind of liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel material and its preparation method and application, the hydrogel material includes liquid metal microsphere, sodium alginate and polyacrylamide form hierarchical porous network and flaky MXene.Preparation step includes: S1.add liquid metal to aqueous solution, ultrasonic dispersion obtains dispersion liquid;S2.dispersion liquid is added to sodium alginate solution, and ultrasonic sodium alginate is obtained to liquid metal water solution;S3.acrylamide is dissolved in deionized water, then sodium alginate is added to liquid metal water solution, then crosslinking agent, initiator and MXene are added, and stirring is uniform;S4.pour into mould heating and form hydrogel.The composite hydrogel material prepared by the present application has the advantages of high tensile rate, strong electromagnetic shielding performance, etc., and can be used as electronic skin for electromagnetic shielding, human health monitoring, man-machine communication, soft robot.

Description

Technical Field

[0001] This invention belongs to the field of flexible electronic devices, and in particular relates to a liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel material, its preparation method and application. Background Technology

[0002] In the digital age, the widespread electromagnetic radiation from electronic devices has raised serious concerns about its various adverse effects on human health, including neurodegenerative diseases, cancer, and other worrying conditions. Therefore, there is an urgent need for EMI shielding materials that possess high EMI shielding effectiveness (SE), good mechanical strength and flexibility, ease of processing, and integrated multifunctionality.

[0003] As a typical flexible material, conductive hydrogels have become a candidate material for flexible electronic devices due to their flexibility, scalability, conductivity, and biocompatibility. However, traditional conductive hydrogels have low mechanical properties and limited functionality, which restricts their application range.

[0004] To address these challenges, dual-network hydrogels with excellent mechanical properties have attracted considerable attention. Porous dual-network hydrogels, through the interaction of a rigid polyelectrolyte network with high cross-linking density as the first network and a low-crosslinked or uncrosslinked neutral network with good deformability and tensile strength as the second network, achieve excellent high tensile strength to meet applications under extreme conditions, providing a platform for multifunctional integrated flexible electronic shielding materials. However, hydrogels with only simple networks suffer from insufficient mechanical properties and limited functionality. Furthermore, hydrogels used in sensors and wearable devices face increasing harmful electromagnetic interference (EMI) or radiation, which can affect the normal operation of hydrogels and pose risks to human health.

[0005] Therefore, there is an urgent need to design multifunctional hydrogels with excellent mechanical properties, high EMI shielding effectiveness (SE), good biocompatibility, and for next-generation smart wearable and even implantable devices. Summary of the Invention

[0006] In view of the deficiencies in the existing technology, the purpose of this application is to provide a liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel material, its preparation method, and its application. The liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel material provided by this invention possesses high toughness, good tensile strength and electrical conductivity, and is biocompatible.

[0007] The technical solutions adopted by the present invention to achieve the above-mentioned objectives are described in detail below; the objectives of the present invention can be achieved through the following technical solutions:

[0008] One of the technical solutions of the present invention provides a liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel material, which includes a hierarchical porous structure and an "island bridge" structure; the hierarchical porous structure is composed of a network reinforced by liquid metal microspheres and a hydrogel dual network, and the "island bridge" structure is composed of liquid metal microspheres and MXene nanosheets.

[0009] Furthermore, the pore size of the hierarchical porous structure is 5–20 μm.

[0010] Furthermore, the MXene nanosheets are uniformly distributed in the hydrogel network, forming an "island bridge" structure with the liquid metal microspheres.

[0011] Island-bridge structures are a special type of nanostructure in chemical materials, generally referring to the morphology of nanoislands distributed on a two-dimensional surface interconnected by connecting structures (bridges). This structure can influence the electrical, optical, and magnetic properties of materials, and is of great significance in nanomaterials research. Specifically: nanoislands are localized protrusions at the nanoscale, which can be single molecular clusters or larger particles; they can be formed from various materials, such as metals, semiconductors, or insulators, and are usually formed naturally during thin film deposition or self-assembly. The bridge structures between islands are connecting parts formed by the continuous distribution of matter. These connections can be linear, branched, or network-like, providing continuous pathways for matter at the nanoscale and potentially affecting electron transport and energy transfer.

[0012] The second technical solution of the present invention provides a method for preparing a liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel material, comprising the following steps:

[0013] S1. Add liquid metal to deionized water, shake well, and then sonicate using a cell disruptor to obtain a uniformly dispersed liquid metal microsphere dispersion.

[0014] S2. Mix the above liquid metal microsphere dispersion with sodium alginate solution, and then perform ultrasonic treatment to obtain an aqueous solution of sodium alginate encapsulating liquid metal;

[0015] S3. Disperse the acrylamide monomer, crosslinking agent, initiator and MXene solution into the above-mentioned aqueous solution of sodium alginate-encapsulated liquid metal and stir until completely dissolved to obtain a mixed solution;

[0016] S4. Quickly pour the mixed solution into the mold and heat it to obtain a hydrogel, which is a liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel material.

[0017] Further, the liquid metal mentioned in step S1 is a 16°C gallium-indium alloy (GaIn). GaIn alloys are solid at room temperature (approximately 16°C or 61°F) but transform into a liquid state upon slightly increasing the temperature. GaIn alloys exhibit super-stretching properties, capable of exhibiting tensile strength exceeding their inherent strength under specific conditions, primarily due to their surface tension-driven deformation mechanism. When subjected to tensile force, elongated droplets spontaneously form on the surface of the GaIn alloy; this phenomenon is known as "droplet stretching" or "capillary-driven deformation of liquid metals," allowing the alloy to be stretched to a certain extent without fracturing. This property of GaIn alloys is fully utilized in applications such as soft electronics, biomedical devices, and wearable technologies.

[0018] Further, the ratio of liquid metal to deionized water in step S1 is (0.5-2) g: 5 mL;

[0019] Furthermore, the sonication time of the cell disruptor in step S1 is 5 to 10 minutes.

[0020] Further, the concentration of the sodium alginate solution in step S2 is 3-5 wt%;

[0021] Furthermore, in step S2, the volume of the liquid metal microsphere dispersion and the sodium alginate solution are equal.

[0022] Furthermore, the ultrasound time in step S2 is 5 to 10 minutes.

[0023] Further, the crosslinking agent in step S3 is any one of N,N-methylenebisacrylamide or dimethyl sulfoxide; the initiator is any one of ammonium persulfate or sodium perbromate; the concentration of the MXene solution is 0-14 mg / mL, and can be 0, the solvent is deionized water, and the solute is MXene material; the MXene material is obtained by chemical etching of the MAX phase material.

[0024] Furthermore, the MAX phase material is a complex metal carbonitride, whose chemical formula can generally be represented as MnAX, where M represents a transition metal, A represents a main group element such as aluminum, titanium, scandium, vanadium, and chromium, and X represents nitrogen or carbon. The characteristics of MAX phase materials include high hardness, high melting point, excellent chemical stability, good thermal conductivity, and unique electrical and optical properties.

[0025] Furthermore, the MAX phase materials specifically include, but are not limited to, the following: TiAlN (titanium aluminum nitride), CrCN (chromium carbon nitride), Ti3AlC2 (titanium trialuminum dicarbide), Ti2AlN (titanium dialuminum nitride), V2AlC (vanadium dialuminum carbide), Mo2FeB2 (molybdenum diiron boronide), and Nb2AlC (niobium dialuminum carbide).

[0026] Further, in step S3, the ratio of acrylamide monomer, crosslinking agent, initiator, MXene solution, and aqueous solution of sodium alginate encapsulating liquid metal is (0.5-3)g:(0.0055-0.0075)g:(0.010-0.0020)g:(2-3)mL:10mL.

[0027] Furthermore, the mold described in step S4 is preferably a rectangular silicone mold;

[0028] Furthermore, the heating temperature in step S4 is 60-80°C, and the heating time is 30-60 minutes.

[0029] The third technical solution of this application provides the application of the above-mentioned liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel material. As a multifunctional integrated flexible electronic device, the liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel material has extremely high electromagnetic shielding performance, reaching 86.6dB; and has strain sensing performance and temperature sensing performance, which can monitor the movement of joints in various parts of the human body and the ambient temperature.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] (1) This invention prepares an ultra-stretchable liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel material by a method of coating liquid metal microspheres with sodium alginate for bidirectional reinforcement. An overall hierarchical porous network reinforcement structure is formed, which greatly improves the elongation and electromagnetic shielding performance of the hydrogel.

[0032] (2) This invention prepares a hierarchical porous hydrogel material with high electrical conductivity. First, the hierarchical porous structure, through the interaction of pores of different sizes, can effectively absorb electromagnetic waves of different wavelengths. Such a structure can achieve high-performance electromagnetic wave shielding, which is particularly important for applications requiring electromagnetic interference suppression. Second, the porous material has a large number of surfaces and interfaces, and electromagnetic waves undergo multiple reflections and scatterings when passing through it, increasing the dissipation path of electromagnetic energy and thus enhancing the shielding efficiency. In addition, due to the enhancing properties of the liquid metal on the network, not only is the stretchability of the hydrogel significantly improved, but the overall electrical conductivity of the hydrogel is also increased, increasing conductive loss and further improving the shielding performance. Finally, this composite hydrogel material is biocompatible, which is crucial for flexible electronic devices applied to the human body.

[0033] (3) The “island-bridge” structure of this invention enables the polarization effect caused by the interlayer interaction of different materials to effectively enhance the loss of electromagnetic waves. When electromagnetic waves pass through these interfaces, multiple interface polarizations occur, which are converted into heat energy, thereby increasing the electromagnetic shielding performance. In addition, the charge transfer and interaction between different materials can lead to changes in electron mobility, which helps to regulate the conductivity of the materials and thus optimize the shielding performance.

[0034] (4) The preparation method of the present invention is simple, stable and controllable, and the final liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel material has the characteristics of high tensile strength, good shielding performance, rich functions and good biocompatibility, providing a new idea for the application of multifunctional integrated wearable devices. Attached Figure Description

[0035] Figure 1 The images show the SEM characterization of the sodium alginate-encapsulated liquid metal dispersion and the liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel finally prepared in Example 16 of this invention.

[0036] Figure 1 The middle mark indicates:

[0037] (a)(b) are SEM images of the liquid metal dispersion encapsulated in sodium alginate; (c)(d) are SEM images of the liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel.

[0038] Figure 2 The stress-strain curve of the sodium alginate / polyacrylamide hydrogel finally prepared in Comparative Example 1 is shown.

[0039] Figure 3 The stress-strain curves of the liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogels finally prepared in Examples 1-4 are shown.

[0040] Figure 4 The electromagnetic shielding performance diagrams are shown for the liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogels finally prepared in Examples 13-16 and the sodium alginate / polyacrylamide hydrogels finally prepared in Comparative Example 1.

[0041] Figure 5 The image shows the monitoring signals of various parts of the human body by a flexible strain sensor made of liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel.

[0042] Figure 5 The middle mark indicates:

[0043] (a) is a schematic diagram of the island bridge structure; (b) is a schematic diagram of the sensing under different stretching rates; (c) is the GF factor of the liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel; (d)(e)(f)(g)(h)(i) are the monitoring signal diagrams of various parts of the human body by the flexible strain sensor of the liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel in Example 16, where (d) is finger bending at different angles, (e) is knee joint movement, (f) is knee joint squatting movement, (g) is elbow joint movement, (h) is rapid finger bending, and (i) is heartbeat detection;

[0044] Figure 6 A temperature sensor based on a liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel transmits signals for ambient temperature and human body monitoring.

[0045] Figure 6 The middle mark indicates:

[0046] (a) Schematic diagram of the temperature sensor for the liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel; (b) Resistance change of the temperature sensor for the liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel at different temperatures; (c) Resistance change of the temperature sensor for the liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel under cycling from 20°C to 60°C; (d) Resistance change of the temperature sensor for the liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel when ice and hot water are close to it; (e) Resistance change of ice at a distance from the liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel. (f) Resistance change of the liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel temperature sensor at different distances; (g) Resistance change of hot water at different distances from the liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel temperature sensor under 0-20 degree cycling; (h) Different temperature detection ranges of the liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel temperature sensor; (i) Different human body temperatures detected by the liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel temperature sensor. Detailed Implementation

[0047] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be described in detail below with reference to specific embodiments. It should be noted that the following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any way. It should be pointed out that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0048] All raw materials used in this invention are not particularly limited in their source; they can be purchased from the market or prepared using conventional methods known to those skilled in the art.

[0049] Example 1:

[0050] First, 0.5g of metal (gallium-indium alloy) was added to 5mL of deionized water, shaken well, and then sonicated for 5min using a cell disruptor to obtain a uniformly dispersed liquid metal microsphere dispersion. Next, the above dispersion was mixed with 5mL of 4wt% sodium alginate solution, and then sonicated for 5min to obtain an aqueous solution of sodium alginate encapsulating liquid metal. Subsequently, 2g of acrylamide monomer, 0.0065g of crosslinking agent N,N-methylenebisacrylamide, 0.015g of initiator ammonium persulfate, and 2.5mL of aqueous solution were dispersed into the above mixture and stirred until completely dissolved. Finally, the mixed solution was quickly poured into a rectangular silicone mold and heated at 60℃ for 30min to obtain a liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel.

[0051] Example 2:

[0052] First, 0.5g of metal (gallium-indium alloy) was added to 5mL of deionized water, shaken well, and then sonicated for 5min using a cell disruptor to obtain a uniformly dispersed liquid metal microsphere dispersion. Next, the above dispersion was mixed with 5mL of 4wt% sodium alginate solution, and then sonicated for 5min to obtain an aqueous solution of sodium alginate encapsulating liquid metal. Subsequently, 2g of acrylamide monomer, 0.0065g of crosslinking agent N,N-methylenebisacrylamide, 0.015g of initiator ammonium persulfate, and 2.5mL of MXene (2mg / mL) solution were dispersed into the above mixture and stirred until completely dissolved. Finally, the mixed solution was quickly poured into a rectangular silicone mold and heated at 60℃ for 30min to obtain a liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel.

[0053] Example 3:

[0054] First, 0.5g of metal (gallium-indium alloy) was added to 5mL of deionized water, shaken well, and then sonicated for 5min using a cell disruptor to obtain a uniformly dispersed liquid metal microsphere dispersion. Next, the above dispersion was mixed with 5mL of 4wt% sodium alginate solution, and then sonicated for 5min to obtain an aqueous solution of sodium alginate encapsulating liquid metal. Subsequently, 2g of acrylamide monomer, 0.0065g of crosslinking agent N,N-methylenebisacrylamide, 0.015g of initiator ammonium persulfate, and 2.5mL of MXene (7mg / mL) solution were dispersed into the above mixture and stirred until completely dissolved. Finally, the mixed solution was quickly poured into a rectangular silicone mold and heated at 60℃ for 30min to obtain a liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel.

[0055] Example 4:

[0056] First, 0.5g of metal (gallium-indium alloy) was added to 5mL of deionized water, shaken well, and then sonicated for 5min using a cell disruptor to obtain a uniformly dispersed liquid metal microsphere dispersion. Next, the above dispersion was mixed with 5mL of 4wt% sodium alginate solution, and then sonicated for 5min to obtain an aqueous solution of sodium alginate encapsulating liquid metal. Subsequently, 2g of acrylamide monomer, 0.0065g of crosslinking agent N,N-methylenebisacrylamide, 0.015g of initiator ammonium persulfate, and 2.5mL of MXene (14mg / mL) solution were dispersed into the above mixture and stirred until completely dissolved. Finally, the mixed solution was quickly poured into a rectangular silicone mold and heated at 60℃ for 30min to obtain a liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel.

[0057] Example 5:

[0058] First, 1g of metal (gallium-indium alloy) was added to 5mL of deionized water, shaken well, and then sonicated for 5min using a cell disruptor to obtain a uniformly dispersed liquid metal microsphere dispersion. Next, the above dispersion was mixed with 5mL of 4wt% sodium alginate solution, and then sonicated for 5min to obtain an aqueous solution of sodium alginate encapsulating liquid metal. Subsequently, 2g of acrylamide monomer, 0.0065g of crosslinking agent N,N-methylenebisacrylamide, 0.015g of initiator ammonium persulfate, and 2.5mL of aqueous solution were dispersed into the above mixture and stirred until completely dissolved. Finally, the mixed solution was quickly poured into a rectangular silicone mold and heated at 60℃ for 30min to obtain a liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel.

[0059] Example 6:

[0060] First, 1g of metal (gallium-indium alloy) was added to 5mL of deionized water, shaken well, and then sonicated for 5min using a cell disruptor to obtain a uniformly dispersed liquid metal microsphere dispersion. Next, the above dispersion was mixed with 5mL of 4wt% sodium alginate solution, and then sonicated for 5min to obtain an aqueous solution of sodium alginate encapsulating liquid metal. Subsequently, 2g of acrylamide monomer, 0.0065g of crosslinking agent N,N-methylenebisacrylamide, 0.015g of initiator ammonium persulfate, and 2.5mL of MXene (2mg / mL) solution were dispersed into the above mixture and stirred until completely dissolved. Finally, the mixed solution was quickly poured into a rectangular silicone mold and heated at 60℃ for 30min to obtain a liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel.

[0061] Example 7:

[0062] First, 1g of metal (gallium-indium alloy) was added to 5mL of deionized water, shaken well, and then sonicated for 5min using a cell disruptor to obtain a uniformly dispersed liquid metal microsphere dispersion. Next, the above dispersion was mixed with 5mL of 4wt% sodium alginate solution, and then sonicated for 5min to obtain an aqueous solution of sodium alginate encapsulating liquid metal. Subsequently, 2g of acrylamide monomer, 0.0065g of crosslinking agent N,N-methylenebisacrylamide, 0.015g of initiator ammonium persulfate, and 2.5mL of MXene (7mg / mL) solution were dispersed into the above mixture and stirred until completely dissolved. Finally, the mixed solution was quickly poured into a rectangular silicone mold and heated at 60℃ for 30min to obtain a liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel.

[0063] Example 8:

[0064] First, 1g of metal (gallium-indium alloy) was added to 5mL of deionized water, shaken well, and then sonicated for 5min using a cell disruptor to obtain a uniformly dispersed liquid metal microsphere dispersion. Next, the above dispersion was mixed with 5mL of 4wt% sodium alginate solution, and then sonicated for 5min to obtain an aqueous solution of sodium alginate encapsulating liquid metal. Subsequently, 2g of acrylamide monomer, 0.0065g of crosslinking agent N,N-methylenebisacrylamide, 0.015g of initiator ammonium persulfate, and 2.5mL of MXene (14mg / mL) solution were dispersed into the above mixture and stirred until completely dissolved. Finally, the mixed solution was quickly poured into a rectangular silicone mold and heated at 60℃ for 30min to obtain a liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel.

[0065] Example 9:

[0066] First, 1.5g of metal (gallium-indium alloy) was added to 5mL of deionized water, shaken well, and then sonicated for 5min using a cell disruptor to obtain a uniformly dispersed liquid metal microsphere dispersion. Next, the above dispersion was mixed with 5mL of 4wt% sodium alginate solution, and then sonicated for 5min to obtain an aqueous solution of sodium alginate encapsulating liquid metal. Subsequently, 2g of acrylamide monomer, 0.0065g of crosslinking agent N,N-methylenebisacrylamide, 0.015g of initiator ammonium persulfate, and 2.5mL of aqueous solution were dispersed into the above mixture and stirred until completely dissolved. Finally, the mixed solution was quickly poured into a rectangular silicone mold and heated at 60℃ for 30min to obtain a liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel.

[0067] Example 10:

[0068] First, 1.5g of metal (gallium-indium alloy) was added to 5mL of deionized water, shaken well, and then sonicated for 5min using a cell disruptor to obtain a uniformly dispersed liquid metal microsphere dispersion. Next, the above dispersion was mixed with 5mL of 4wt% sodium alginate solution, and then sonicated for 5min to obtain an aqueous solution of sodium alginate encapsulating liquid metal. Subsequently, 2g of acrylamide monomer, 0.0065g of crosslinking agent N,N-methylenebisacrylamide, 0.015g of initiator ammonium persulfate, and 2.5mL of MXene (2mg / mL) solution were dispersed into the above mixture and stirred until completely dissolved. Finally, the mixed solution was quickly poured into a rectangular silicone mold and heated at 60℃ for 30min to obtain a liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel.

[0069] Example 11:

[0070] First, 1.5g of metal (gallium-indium alloy) was added to 5mL of deionized water, shaken well, and then sonicated for 5min using a cell disruptor to obtain a uniformly dispersed liquid metal microsphere dispersion. Next, the above dispersion was mixed with 5mL of 4wt% sodium alginate solution, and then sonicated for 5min to obtain an aqueous solution of sodium alginate encapsulating liquid metal. Subsequently, 2g of acrylamide monomer, 0.0065g of crosslinking agent N,N-methylenebisacrylamide, 0.015g of initiator ammonium persulfate, and 2.5mL of MXene (7mg / mL) solution were dispersed into the above mixture and stirred until completely dissolved. Finally, the mixed solution was quickly poured into a rectangular silicone mold and heated at 60℃ for 30min to obtain a liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel.

[0071] Example 12:

[0072] First, 1.5g of metal (gallium-indium alloy) was added to 5mL of deionized water, shaken well, and then sonicated for 5min using a cell disruptor to obtain a uniformly dispersed liquid metal microsphere dispersion. Next, the above dispersion was mixed with 5mL of 4wt% sodium alginate solution, and then sonicated for 5min to obtain an aqueous solution of sodium alginate encapsulating liquid metal. Subsequently, 2g of acrylamide monomer, 0.0065g of crosslinking agent N,N-methylenebisacrylamide, 0.015g of initiator ammonium persulfate, and 2.5mL of MXene (14mg / mL) solution were dispersed into the above mixture and stirred until completely dissolved. Finally, the mixed solution was quickly poured into a rectangular silicone mold and heated at 60℃ for 30min to obtain a liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel.

[0073] Example 13:

[0074] First, 2g of metal (gallium-indium alloy) was added to 5mL of deionized water, shaken well, and then sonicated for 5min using a cell disruptor to obtain a uniformly dispersed liquid metal microsphere dispersion. Next, the above dispersion was mixed with 5mL of 4wt% sodium alginate solution, and then sonicated for 5min to obtain an aqueous solution of sodium alginate encapsulating liquid metal. Subsequently, 2g of acrylamide monomer, 0.0065g of crosslinking agent N,N-methylenebisacrylamide, 0.015g of initiator ammonium persulfate, and 2.5mL of aqueous solution were dispersed into the above mixture and stirred until completely dissolved. Finally, the mixed solution was quickly poured into a rectangular silicone mold and heated at 60℃ for 30min to obtain a liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel.

[0075] Example 14:

[0076] First, 2g of metal (gallium-indium alloy) was added to 5mL of deionized water, shaken well, and then sonicated for 5min using a cell disruptor to obtain a uniformly dispersed liquid metal microsphere dispersion. Next, the above dispersion was mixed with 5mL of 4wt% sodium alginate solution, and then sonicated for 5min to obtain an aqueous solution of sodium alginate encapsulating liquid metal. Subsequently, 2g of acrylamide monomer, 0.0065g of crosslinking agent N,N-methylenebisacrylamide, 0.015g of initiator ammonium persulfate, and 2.5mL of MXene (2mg / mL) solution were dispersed into the above mixture and stirred until completely dissolved. Finally, the mixed solution was quickly poured into a rectangular silicone mold and heated at 60℃ for 30min to obtain a liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel.

[0077] Example 15:

[0078] First, 2g of metal (gallium-indium alloy) was added to 5mL of deionized water, shaken well, and then sonicated for 5min using a cell disruptor to obtain a uniformly dispersed liquid metal microsphere dispersion. Next, the above dispersion was mixed with 5mL of 4wt% sodium alginate solution, and then sonicated for 5min to obtain an aqueous solution of sodium alginate encapsulating liquid metal. Subsequently, 2g of acrylamide monomer, 0.0065g of crosslinking agent N,N-methylenebisacrylamide, 0.015g of initiator ammonium persulfate, and 2.5mL of MXene (7mg / mL) solution were dispersed into the above mixture and stirred until completely dissolved. Finally, the mixed solution was quickly poured into a rectangular silicone mold and heated at 60℃ for 30min to obtain a liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel.

[0079] Example 16:

[0080] First, 2g of metal (gallium-indium alloy) was added to 5mL of deionized water, shaken well, and then sonicated for 5min using a cell disruptor to obtain a uniformly dispersed liquid metal microsphere dispersion. Next, the above dispersion was mixed with 5mL of 4wt% sodium alginate solution, and then sonicated for 5min to obtain an aqueous solution of sodium alginate encapsulating liquid metal. Subsequently, 2g of acrylamide monomer, 0.0065g of crosslinking agent N,N-methylenebisacrylamide, 0.015g of initiator ammonium persulfate, and 2.5mL of MXene (14mg / mL) solution were dispersed into the above mixture and stirred until completely dissolved. Finally, the mixed solution was quickly poured into a rectangular silicone mold and heated at 60℃ for 30min to obtain a liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel.

[0081] For ease of understanding, the raw material variables of the above embodiments are summarized in Table 1, as follows:

[0082] Table 1 Summary of Raw Material Variables in Examples 1-16

[0083] variable Gallium-indium alloy dosage (g) MXene solution concentration (mg / mL) Example 1 0.5 0 Example 2 0.5 2 Example 3 0.5 7 Example 4 0.5 14 Example 5 1.0 0 Example 6 1.0 2 Example 7 1.0 7 Example 8 1.0 14 Example 9 1.5 0 Example 10 1.5 2 Example 11 1.5 7 Example 12 1.5 14 Example 13 2.0 0 Example 14 2.0 2 Example 15 2.0 7 Example 16 2.0 14

[0084] Comparative Example 1:

[0085] The comparative example does not contain liquid metal or MXene, and the preparation steps are as follows:

[0086] 5 mL of 4 wt% sodium alginate solution was dispersed in a mixture of 2 g acrylamide monomer, 0.0065 g crosslinking agent N,N-methylenebisacrylamide, 0.015 g initiator ammonium persulfate, and 2.5 mL of aqueous solution, and stirred until completely dissolved. The mixture was then quickly poured into a rectangular silicone mold and heated at 60 °C for 30 minutes to obtain a sodium alginate / polyacrylamide composite hydrogel.

[0087] The present invention conducted the following tests on Examples 1-16 and Comparative Example 1:

[0088] (1) The morphology of the sample was observed using a scanning electron microscope (SEM).

[0089] Figure 1 The images shown are SEM images of the sodium alginate-encapsulated liquid metal dispersion and the liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel finally obtained in Example 16 of this invention; (a) and (b) are SEM images of the sodium alginate-encapsulated liquid metal dispersion; (c) and (d) are SEM images of the liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel.

[0090] Figure 1(a) and (b) show SA@LM particles (sodium alginate-encapsulated liquid metal particles) with spherical morphology and a diameter of less than 10 μm at different magnifications, as well as a hydrogel network with a hierarchical porous structure, with macropores of approximately 10-30 μm in diameter and micropores of approximately 1-10 μm in diameter.

[0091] (2) EMI SE values ​​and electromagnetic parameters in the 8.2–12.4 GHz frequency range were measured using a rectangular waveguide (32117) and a two-port network analyzer (3672B-S, Ceyear, China). The hydrogel samples were cut to dimensions of 22.86 mm × 10.16 mm (length × width) within the 8.2–12.4 GHz (X-band) test frequency range. S-parameters (S...) were recorded. 11 and S 22 The power coefficients of reflection (R), transmission (T), and absorption (A) are calculated according to the following formulas.

[0092] R = |S 11 | 2 =|S 22 | 2 (1)

[0093] Among them, S 11 The input reflection parameter is the input return loss; S 22 This refers to the output reflection parameter, which is the output return loss.

[0094] T = |S 11 | 2 =|S 22 | 2 (2)

[0095] Among them, S 11 The input reflection parameter is the input return loss; S 22 This refers to the output reflection parameter, which is the output return loss.

[0096] A = 1 - RT (3)

[0097] Figure 2 This indicates that the stress and strain of the comparative model are around 60 kPa and 600%, which is insufficient for applications in complex scenarios.

[0098] Figure 3 This indicates that the embodiments of this application can be adjusted within the strain range of 2000%-5000% and the stress can be adjusted to around 50-300 kPa, which can meet the application requirements in complex scenarios.

[0099] Figure 4The results show that the hydrogel achieved a maximum EMI SE value of 86.6 dB with 2 g of liquid metal and 14 mg / ml MXene as conductive fillers. It can be observed that the improved conductive network and the addition of MXene significantly enhanced the shielding performance of the hydrogel itself. The introduction of more diverse interfaces and the appropriate increase in liquid metal can effectively improve the EMI shielding performance of the hydrogel. While the shielding mechanism is primarily reflection-based, the absorption coefficient A increases with increasing liquid metal and MXene content, indicating a higher absorption ratio, which meets the needs of future electromagnetic shielding material development.

[0100] (3) Hydrogel was used as a sensor and directly attached to the volunteer's fingers, wrists, elbows, knees and chest. The electrical signals generated by the sensor during movement of each part were recorded by a multimeter.

[0101] Figure 5 Figures show the monitoring signals of various parts of the human body by a flexible strain sensor based on a liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel. Figure (a) is a schematic diagram of the island bridge structure. Figure (b) shows the sensing signal under different stretching rates. Figure (c) shows the GF factor of the liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel. Figures (d)(e)(f)(g)(h)(i) show the monitoring signals of various parts of the human body by the flexible strain sensor based on the liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel of Example 16, where (d) shows finger bending at different angles, (e) shows knee joint movement, (f) shows knee squatting movement, (g) shows elbow joint movement, (h) shows rapid finger bending, and (i) shows heart rate detection.

[0102] This application obtains the sensing performance of PSLM hydrogel by testing the rate of change of resistivity of PSLM composite hydrogel at different strains (150%, 400%, 600%, 1000%, and 1200%). Figure 5 (b) Due to the superstretchability and flexibility of the PSLM composite hydrogel, it exhibits excellent sensing performance across a wide range of tensile strains, from low to high. The R / R0 value increases significantly with increasing strain, and after strain recovery, it quickly returns to its initial state, demonstrating excellent stability and reversibility. Figure 5The high sensitivity of the PSLM composite hydrogel sensor was revealed by the strain coefficient (GF). GF gradually increases from 1.65 at low strain rates (0–150%) with increasing strain. When the applied strain is 150–800%, GF increases by 2.68. When the strain is 800–1000%, GF is 4.42, showing an increasing trend with increasing strain. This application also uses PSLM hydrogel as a conductor for LED lights, achieving a breathing light effect. These phenomena can be attributed to the uniformly dispersed LM droplets changing from spherical to needle-like after stretching, increasing the conductive sites connecting the MXene nanosheets and forming a longer conductive path, demonstrating the high sensitivity of the PSLM composite hydrogel. The PSLM composite hydrogel is attached to human body parts to detect real-time human activity and health status. When the PSLM composite hydrogel sensor is attached to a finger, the signals generated when the finger joint is bent at 0°, 30°, 60°, and 90° can be detected immediately. When the finger remains at the corresponding angle, the hydrogel can maintain the current signal. The knuckles are then straightened in two steps from a 90° bend: the first step restores the angle to 45°, and the second step fully restores it to 0°. Figure 5 d). The signal response of the PSLM composite hydrogel perfectly validated the finger recovery process, demonstrating the hydrogel's excellent reversibility and stability. For example... Figure 5 As shown in h, when the finger is bent rapidly at different angles, the PSLM composite hydrogel can perform surprising signal detection. Figure 5 e demonstrated the hydrogel's detection of knee flexion at 90°, compared to Figure 5 The difference in signal strength observed in the squatting motion of f was mainly due to the squatting angle being greater than 90°. Hydrogel was applied to the elbow to detect the arm flexion motion signal. Figure 5 g). Figure 5 The image shows the heartbeat signal detected by the PSLM composite hydrogel attached to the left chest. The signal fluctuates around 0.6%, demonstrating the hydrogel's ability to detect minute strains and vibrations. These results indicate that strain sensors based on PSLM composite hydrogels have great potential for applications in flexible wearable electronics.

[0103] (4) Use hydrogel as a temperature sensor to record electrical signals generated by changes in ambient temperature and human body temperature.

[0104] Figure 6This figure shows the monitoring signals of an ambient temperature and a human body from a temperature sensor made of liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel. Figure (a) shows a schematic diagram of the temperature sensor; (b) shows the resistance change of the temperature sensor at different temperatures; (c) shows the resistance change of the temperature sensor under a 20°C-60°C cycling cycle; (d) shows the resistance change when ice and hot water are near the temperature sensor; and (e) shows the resistance change when ice is at a distance from the liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel. The resistance changes of the acrylamide composite hydrogel temperature sensor at different distances: (f) shows the resistance change of hot water at different distances from the liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel temperature sensor; (g) shows the resistance change of the liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel temperature sensor under 0-20 degree cycling; (h) shows different temperature detection ranges of the liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel temperature sensor; and (i) shows different human body temperatures detected by the liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel temperature sensor.

[0105] like Figure 6 As shown in b, this application heated the PSLM composite hydrogel from 20℃ to 60℃ and calculated the TCR value of the PSLM composite hydrogel by measuring the change in the hydrogel conductivity to be -1.1%℃-1 (R2=0.996), indicating that the hydrogel has a negative temperature coefficient of resistance and a highly linear thermal response. Figure 6 c shows that the hydrogel sensor maintained a repeatable resistance signal for 5 cycles within a wide temperature sensing range (20℃-60℃) without significant signal drift, demonstrating the stability, repeatability, and practicality of the PSLM composite hydrogel temperature sensor. This application can utilize this characteristic of the PSLM composite hydrogel temperature sensor for ambient temperature detection and cold / heat source location. First, ice cubes and beakers containing 40℃ water were momentarily brought into contact with the PSLM composite hydrogel temperature sensor, respectively. The sensor instantaneously exhibited a change in resistance signal (…). Figure 6 d). Maintain contact between the ice and the beaker for approximately 22 seconds and 26 seconds respectively, ensuring stability. Then remove the ice and beaker. Due to the extended contact time, the PSLM composite hydrogel temperature sensor recovers in approximately 1 minute. Figure 6As shown in Figure e, when ice is used alone for cold source positioning, the resistance gradually increases with distance as the ice approaches the PSLM composite hydrogel temperature sensor, exhibiting different resistance signals at different distances. This response is instantaneous and accurately reflects the location of the cold source. When a beaker containing 40°C water is used alone for cold source positioning, the resistance gradually decreases with distance as the beaker approaches the PSLM composite hydrogel temperature sensor, exhibiting different resistance signals at different distances. This response is instantaneous and accurately reflects the location of the heat source. Figure 6 f).

[0106] The practical application of PSLM composite hydrogel temperature sensors also requires meeting requirements for wide-range detection capability and repeatability. Specifically, cyclic simulations were conducted for three experimental cycles between 0℃ and 40℃. Figure 6 g) A nearly constant response was obtained over three cycles, indicating good durability. Heating the PSLM composite hydrogel temperature sensor from 0°C to 100°C still exhibited a highly linear thermal response. To further explore the detection range of the hydrogel, this application found that the lowest detection range could reach 0.1°C by controlling the heating temperature, which meets the requirements for human body temperature monitoring. Figure 6 Therefore, this application tested the response of the PSLM composite hydrogel temperature sensor within the human body temperature range (36.5℃-41℃). Due to its excellent thermal sensitivity, signal changes could be observed within a narrow range of human body temperature. Figure 6 i).

[0107] The above experiments demonstrate that the PSLM composite hydrogel temperature sensor excels in temperature detection range, sensitivity, resolution, cold / heat source detection response speed, and stability, showcasing its promising application potential.

[0108] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for preparing a liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel material, characterized in that, The composite hydrogel material includes a hierarchical porous structure and an "island-bridge" structure; the hierarchical porous structure consists of a network reinforced by liquid metal microspheres and a hydrogel dual network, and the pore size of the hierarchical porous structure is 5~20μm; the "island-bridge" structure consists of liquid metal microspheres and MXene nanosheets, and the MXene nanosheets are uniformly distributed in the hydrogel network, forming an "island-bridge" structure with the liquid metal microspheres; The preparation method of this composite hydrogel material includes the following steps: S1. Add liquid metal to deionized water, shake well, and then sonicate using a cell disruptor to obtain a uniformly dispersed liquid metal microsphere dispersion. S2. Mix the above liquid metal microsphere dispersion with sodium alginate solution, and then perform ultrasonic treatment to obtain an aqueous solution of sodium alginate encapsulating liquid metal; S3. Disperse the acrylamide monomer, crosslinking agent, initiator and MXene solution into the above-mentioned aqueous solution of sodium alginate-encapsulated liquid metal and stir until completely dissolved to obtain a mixed solution; S4. Quickly pour the mixed solution into the mold and heat it to obtain a hydrogel, which is a liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel material. The liquid metal mentioned in step S1 is a gallium-indium alloy; The concentration of the sodium alginate solution in step S2 is 3-5 wt%; The concentration of the MXene solution in step S3 is 0~14 mg / mL, and is not 0; The ratio of the amounts of acrylamide monomer, crosslinking agent, initiator, MXene solution and sodium alginate-encapsulated liquid metal in step S3 is (0.5-3) g : (0.0055-0.0075) g : (0.010-0.0020) g : (2-3) mL : 10 mL.

2. The method for preparing a liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel material according to claim 1, characterized in that, In step S1, the ratio of liquid metal to deionized water is (0.5~2) g: 5 mL; the sonication time of the cell disruptor is 5~10 min.

3. The method for preparing a liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel material according to claim 1, characterized in that, The ultrasound session lasted 5 to 10 minutes.

4. The method for preparing a liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel material according to claim 1, characterized in that, The crosslinking agent in step S3 is N,N-methylenebisacrylamide; the initiator is ammonium persulfate.

5. The method for preparing a liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel material according to claim 1, characterized in that, In step S3, the solvent in the MXene solution is deionized water, and the solute is MXene material.

6. The method for preparing a liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel material according to claim 5, characterized in that, The MXene material is obtained by chemical etching of a MAX phase material, wherein the MAX phase material is any one of titanium aluminum nitride, chromium carbon nitride, titanium trialuminum dicarbide, vanadium dialuminum carbide, molybdenum diiron boronide, or niobium dialuminum carbide.

7. The method for preparing a liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel material according to claim 1, characterized in that, The heating temperature in step S4 is 60~80℃, and the heating time is 30~60 minutes.

8. The application of a liquid metal / MXene / sodium alginate / polyacrylamide composite hydrogel material obtained by the preparation method according to any one of claims 1-7, characterized in that, The composite hydrogel material serves as a multifunctional integrated flexible electronic device for strain sensing and / or temperature sensing.

Images