Temperature-responsive smart adhesive gelatin-based conductive hydrogel and preparation method and application thereof

Abstract

The application discloses a temperature response adhesion intelligent gelatin-based conductive hydrogel and a preparation method and application thereof. The hydrogel takes methacrylated gelatin as a main skeleton component, takes polymeric gallic acid as a temperature response functional component, and takes PEDOT:SCS-SH as a conductive unit. In an aqueous system, in-situ radical polymerization is conducted under the initiation of ammonium persulfate / tetramethylethylenediamine to construct a multiple cross-linking network structure. The methacrylated gelatin forms a continuous chemical covalent cross-linking network as a main skeleton. The polymeric gallic acid interacts with the skeleton network through dynamic hydrogen bonds to endow the material with temperature-dependent adhesion regulation characteristics. The PEDOT:SCS-SH is embedded in the system to form an electron-ion synergistic conductive path. The hydrogel obtained in this way has good flexibility, mechanical stability, electrical conductivity and temperature response adhesion performance, and is suitable for fields of flexible sensors, wearable electronic devices and biological interface attachment materials.

Description

Technical Field

[0002] This invention belongs to the field of hydrogel materials technology, specifically relating to a temperature-responsive smart adhesive gelatin-based conductive hydrogel, its preparation method, and its application. Background Technology

[0004] Gelatin-based conductive hydrogels, derived from the hydrolysis products of natural collagen, possess excellent biocompatibility, biodegradability, and a microenvironment similar to the extracellular matrix, exhibiting unique advantages in wearable electronic devices, flexible sensing, and biointerface adhesion.

[0005] Current research has systematically explored the performance and applications of gelatin-based conductive hydrogels. For example, patent document CN202511751773.8 discloses a high compressive strength ion-conductive gelatin hydrogel and its preparation method. By introducing sodium lactate and montmorillonite into the gelatin system, an ion-conductive composite gelatin hydrogel was developed, which combines high compressive strength with excellent ion conductivity, effectively improving the shortcomings of poor mechanical properties and poor ion conductivity of traditional gelatin hydrogels. Patent document CN202111600582.3 discloses a high-strength, high-value-added gelatin-based conductive hydrogel and its preparation method and applications. By introducing dialdehyde nanocellulose and metal solution into the gelatin system, a high-strength, high-value-added gelatin-based conductive hydrogel was developed, which combines excellent tensile properties, compressive strength, conductivity, self-healing, and reusability, overcoming the shortcomings of poor application performance of existing natural polymer hydrogels. Patent document CN202310234946.3 discloses a gelatin / microfibrillated cellulose / graphene conductive hydrogel, its preparation method, and its applications. By introducing microfibrillated cellulose and graphene into a gelatin system, a gelatin / microfibrillated cellulose / graphene conductive hydrogel was developed, exhibiting excellent mechanical properties, conductivity, and overall performance, demonstrating its application potential in flexible sensors, especially wearable flexible sensors. However, most existing gelatin-based conductive hydrogel systems still face problems such as a single network structure hierarchy, insufficient interfacial interactions, and limited multifunctional synergistic capabilities, making it difficult to achieve an effective balance between high strength, high toughness, and high functionality. Patent document CN202410859978.7 discloses a photocurable biomass-based dual-network conductive hydrogel and its preparation method. This method uses methacrylamide gelatin as the network framework and introduces MXene@TA@PEDOT:PSS conductive components to construct a dual-network structure, providing a reference for the structural design of gelatin-based conductive hydrogels. Patent document CN202211581728.9 discloses a conductive hydrogel bio-interface material, its preparation method, and its application. This hydrogel composition, through the combination of modified hydrogel and functional groups, significantly improves interfacial stability and biocompatibility, providing a technical foundation for the application of conductive hydrogels in bio-interfaces and medical monitoring. The aforementioned patent documents all propose gelatin-based conductive hydrogel systems and their modification strategies, achieving certain results in improving conductivity, mechanical properties, and interfacial adhesion. However, there is no record of a gelatin-based conductive hydrogel with methacrylamide as the main skeleton component, polymerized gallic acid as the temperature-responsive functional component, and PEDOT:SCS-SH as the conductive unit, constructed through in-situ free radical polymerization in an aqueous system initiated by ammonium persulfate / tetramethylethylenediamine to build a multi-crosslinked network structure, ultimately obtaining a gelatin-based conductive hydrogel with good flexibility, mechanical stability, electrical conductivity, and temperature-responsive adhesion properties.

[0006] In addition, the prior art patent document CN202411176808.5 discloses an antibacterial and antioxidant composite hydrogel, its preparation method and application. The composite hydrogel is a hydrogel formed by interpenetrating crosslinking of zinc-loaded lithium saponite, gallic acid-grafted methacrylamide gelatin and arginine-grafted methacrylamide chitosan. Using biocompatible gelatin and chitosan as base materials, they are modified by grafting to form gallic acid-methacrylamide gelatin and arginine-methacrylamide chitosan, which are then mixed with zinc-lithium saponite to prepare a stock solution. Photocrosslinking is then performed to form a hydrogel. This hydrogel has good antibacterial, antioxidant, biocompatibility and blood compatibility. Patent document CN202311592931.0 discloses a hydrogel / gauze composite dressing capable of scavenging reactive oxygen species and its preparation method. The method involves mixing and stirring a methacrylamide-modified natural polymer solution, an aldehyde-modified natural polymer solution, and a photoinitiator to obtain a precursor solution. Gauze is then soaked in the precursor solution, followed by in-situ molding under ultraviolet light to obtain the hydrogel / gauze composite dressing. An antioxidant hydrogel / gauze composite dressing is obtained by crosslinking gallic acid. The carboxyl groups of gallic acid undergo an amide reaction with the amino groups of the natural polymer, and the phenolic hydroxyl groups of gallic acid form hydrogen bonds with the polymer to improve mechanical properties. The phenolic hydroxyl groups of gallic acid synergistically enhance adhesion properties with the aldehyde-modified natural polymer. Simultaneously, the slow release of gallic acid endows the hydrogel / gauze composite dressing with a long-lasting ability to scavenge reactive oxygen species, regulating the tissue microenvironment at the skin wound site and promoting wound healing. However, the aforementioned patent documents do not contain any record of using methacrylamide gelatin as the main skeleton component, polymerized gallic acid as the temperature-responsive functional component, and PEDOT:SCS-SH as the conductive unit, to construct a multi-crosslinked network structure through in-situ free radical polymerization in an aqueous system initiated by ammonium persulfate / tetramethylethylenediamine, ultimately producing a gelatin-based conductive hydrogel with good flexibility, mechanical stability, electrical conductivity, and temperature-responsive adhesion properties.

[0007] Currently, existing gelatin-based conductive hydrogels still face several limitations, including poor mechanical properties of pure gelatin networks, and the introduction of conductive polymers or nanofillers often leads to filler agglomeration due to insufficient interfacial compatibility, making it difficult to simultaneously achieve high conductivity and high tensile / toughness. Insufficient utilization of the active groups in gelatin molecules results in insufficient interfacial adhesion in dynamic deformation environments, easily leading to signal distortion or detachment. Furthermore, current research strategies for hydrogel systems are limited, making it difficult to simultaneously achieve a high degree of integration of high conductivity, excellent soft and hard mechanical properties, broad surface adhesion capabilities, and temperature-responsive adhesion regulation performance in gelatin-based material systems. This invention addresses these technical problems by proposing a multi-crosslinked temperature-responsive adhesive conductive hydrogel system based on the synergistic combination of methacryloyl gelatin, polymeric gallic acid, and PEDOT:SCS-SH. Through the rational design of chemical covalent crosslinking and dynamic physical crosslinking network structures, the overall performance of the hydrogel material is effectively improved, overcoming the shortcomings of existing technologies. Therefore, developing a multifunctional hydrogel material that organically integrates the bio-based properties of gelatin with high conductivity, excellent mechanical properties, and stable interfacial adhesion is a core technical problem that urgently needs to be solved in this field. Summary of the Invention

[0009] The technical problem solved by this invention is to provide a temperature-responsive smart adhesive gelatin-based conductive hydrogel and its preparation method. This method uses methacrylamide gelatin as the three-dimensional network framework of the hydrogel and endows it with temperature-responsive adhesive function. Polymeric gallic acid is introduced to enhance interfacial adhesion. At the same time, PEDOT:SCS-SH is used as the conductive unit. Through the construction of a dynamic hydrogen bond network and an electron-ion synergistic conductive network, a multifunctional smart gelatin-based conductive hydrogel with temperature-controllable adhesion, stable conductivity and excellent mechanical flexibility is finally prepared, so as to break through the application bottleneck of traditional gelatin-based conductive hydrogels. The prepared gelatin-based conductive hydrogel is suitable for adhesive materials in wearable electronic devices, flexible sensors or bio-interfaces.

[0010] To solve the above-mentioned technical problems, this invention adopts the following technical solution: a method for preparing a temperature-responsive smart adhesive gelatin-based conductive hydrogel. The method uses methacrylamide gelatin as the backbone, polymerized gallic acid as the structure regulating component, and PEDOT:SCS-SH as the conductive unit. The temperature-responsive smart adhesive gelatin-based conductive hydrogel is prepared through an ammonium persulfate / tetramethylethylenediamine crosslinking system. The specific preparation steps are as follows:

[0011] Step S1: Dissolve gelatin in PBS buffer, add methacrylic anhydride and react at 40-70°C to obtain methacrylamide gelatin. Then, dilute with PBS buffer to terminate the reaction, dialyze and freeze dry to obtain solid methacrylamide gelatin.

[0012] Step S2: Dissolve gallic acid in deionized water, then add alkaline solution to adjust the pH of the mixture to 7-9, and then react in air to obtain polymerized gallic acid solution;

[0013] Step S3: Chitosan is dissolved in acetic acid solution, and 1,3-propanesulfonyl lactone is added under nitrogen protection and stirred to react. The reaction solution is precipitated in cold acetone, washed with methanol, and then vacuum dried to obtain SCS. SCS is dispersed in deionized water, and HOBt, N-acetyl-L-cysteine, and EDC·HCl are added and stirred to react at room temperature. The reaction solution is dialyzed and then freeze-dried to obtain SCS-SH. SCS-SH and EDOT monomer are dissolved in a water / ethanol mixed solvent, and ammonium persulfate solution is added and stirred to react. The reaction product is washed with water and ethanol by centrifugation, and then vacuum dried to obtain solid powder PEDOT:SCS-SH. The obtained solid powder is dissolved in deionized water to obtain PEDOT:SCS-SH dispersion.

[0014] Step S4: At 40~80℃, dissolve methacrylamide gelatin in deionized water, cool to room temperature, add polymeric gallic acid aqueous solution and stir to mix evenly to obtain a mixed solution, then add PEDOT:SCS-SH dispersion to the mixed solution and continue stirring until uniformly dispersed, then add initiator ammonium persulfate and catalyst tetramethylethylenediamine in sequence and stir thoroughly to remove bubbles until the solution presents a uniform and stable reaction system;

[0015] Step S5: Pour the mixed solution obtained in step S4 into a mold and gelatinize it at 30~50℃, then demold to obtain a temperature-responsive smart adhesive gelatin-based conductive hydrogel.

[0016] Further preferably, the mass ratio of gelatin to methacrylic anhydride in step S1 is 5:(3.5~4.5).

[0017] Further preferred, the mass fraction of the polymerized gallic acid solution in step S2 is 0.5%~1.5%.

[0018] Further preferably, the mass fraction of the PEDOT:SCS-SH dispersion in step S3 is 4%~6%.

[0019] Further optimization involves adding the following components in step S4: an aqueous solution of polymeric gallic acid accounting for 10%–20% of the total mass of the hydrogel; a PEDOT:SCS-SH dispersion accounting for 1%–5% of the total mass of the hydrogel; an initiator of ammonium persulfate accounting for 1%–2% of the total mass of the hydrogel; a catalyst of tetramethylethylenediamine accounting for 0.02%–0.2% of the total mass of the hydrogel; deionized water accounting for 40%–80% of the total mass of the hydrogel; and methacryloyl gelatin accounting for 5%–15% of the total mass of the hydrogel.

[0020] The temperature-responsive smart adhesive gelatin-based conductive hydrogel of this invention is prepared by the above method. The hydrogel uses methacrylamide gelatin as the main skeleton component, polymeric gallic acid as the temperature-responsive functional component, and PEDOT:SCS-SH as the conductive unit. In an aqueous system, it undergoes in-situ free radical polymerization under the initiation of ammonium persulfate / tetramethylethylenediamine to construct a multi-linked network structure. Methacrylamide gelatin forms a continuous chemical covalent cross-linked network as the main skeleton, and polymeric gallic acid interacts with the skeleton network through dynamic hydrogen bonds, giving the material temperature-dependent adhesion regulation characteristics. PEDOT:SCS-SH is embedded in the system to form an electron-ion synergistic conductive pathway, so that the hydrogel has excellent fracture resistance, temperature-responsive adhesion, precisely controllable swelling performance, excellent conductivity, and cycle stability, and also has the sensing performance of rapid mechanical deformation detection.

[0021] The temperature-responsive smart adhesive gelatin-based conductive hydrogel described in this invention is used as an adhesive material for wearable electronic devices, flexible sensors, or biointerfaces.

[0022] Compared with the prior art, the present invention has at least the following advantages or beneficial effects:

[0023] (1) The present invention provides temperature-responsive intelligent adhesion function through methacrylamide gelatin, and polymerizes gallic acid to enhance interfacial adhesion, so that the hydrogel forms a strong interfacial bond with the skin surface under body temperature environment and the adhesion force is significantly reduced under low temperature conditions, thereby endowing the hydrogel with temperature-responsive adhesion function and realizing intelligent switching between adhesion and peeling.

[0024] (2) This invention utilizes the synergistic effect of the electron transport channels of the PEDOT conjugated main chain and the ion migration channels of the SCS-SH side chain ionic groups to construct a stable electron-ion dual-pathway conductive network in the methacrylamide gelatin backbone, which effectively improves the conductivity of the hydrogel while maintaining the flexibility and structural integrity of the network.

[0025] (3) The present invention uses methacrylated gelatin, a natural gelatin derivative, as the main skeleton and polymerized gallic acid as a plant polyphenol derivative. The raw materials are abundant, biocompatible and degradable. The preparation process is carried out in an aqueous system, with mild conditions, simple operation and environmental friendliness.

[0026] (4) By synergistically controlling the content of methacrylamide gelatin and the amount of polymeric gallic acid added, the present invention can achieve systematic optimization of the mechanical properties, electrical conductivity, swelling properties and temperature-responsive adhesion properties of hydrogel, providing flexible adjustment space for the customized design of material properties under different application scenarios. Attached Figure Description

[0028] Figure 1 The swelling ratios of hydrogels with different GelMA contents (Examples 1-5) are given.

[0029] Figure 2 The swelling ratios of hydrogels with different PGA contents (Examples 1, 6-8 and Comparative Example 1) are given.

[0030] Figure 3 Stress-strain curves of hydrogels with different GelMA contents (Examples 1-5).

[0031] Figure 4 Stress-strain curves of hydrogels with different PGA contents (Examples 1, 6-8 and Comparative Example 1).

[0032] Figure 5 Adhesion curves of hydrogels with different PGA contents (Examples 1, 6-8 and Comparative Example 1).

[0033] Figure 6 The temperature responsiveness and vertical multi-substrate adhesion ability of the temperature-responsive adhesive smart gelatin-based conductive hydrogel prepared in Example 1 are demonstrated.

[0034] Figure 7 The adhesion curves of the temperature-responsive adhesive smart gelatin-based conductive hydrogel prepared in Example 1 are shown at body temperature and after ice application.

[0035] Figure 8 Impedance curves of conductive hydrogel (Example 1) and hydrogel without conductive agent (Comparative Example 2).

[0036] Figure 9 The results show the real-time resistance response of the temperature-responsive adhesive smart gelatin-based conductive hydrogel prepared in Example 1 under three reciprocating bending-straightening movements of a finger. Detailed Implementation

[0038] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments, but this should not be construed as limiting the invention. Unless otherwise specified, the technical means used in the following embodiments are conventional means well known to those skilled in the art, and the materials, reagents, etc. used in the following embodiments are commercially available unless otherwise specified.

[0039] In the various embodiments of the present invention, the various abbreviations respectively represent:

[0040] GelMA: Methacrylated gelatin

[0041] PGA: Polygallic Acid

[0042] APS: Ammonium persulfate

[0043] TEMED: Tetramethylethylenediamine

[0044] Example 1

[0045] This embodiment is the optimal embodiment. The total mass of the hydrogel raw material is 12.1155 g, and the mass fraction of each component is as follows: GelMA 12.38 wt%, PGA aqueous solution 16.51 wt%, PEDOT:SCS-SH dispersion 3.30 wt%, APS 1.65 wt%, TEMED 0.13 wt%, and deionized water 66.03 wt%.

[0046] Step S1: In a 60℃ water bath, take 8.0g of deionized water and place it in a beaker. Add 1.5g of GelMA and stir until completely dissolved. After cooling to room temperature, add 2.0g of 1% PGA aqueous solution and stir to mix evenly.

[0047] Step S2: Add 0.4g of 5% PEDOT:SCS-SH dispersion to the solution obtained in step S1, stir to disperse it fully, then add 0.2g of APS and 0.0155g of TEMED in sequence, stir to mix evenly, remove air bubbles by ultrasonication, and pour into a mold.

[0048] Step S3: Place the above pregel mixed solution into a 40℃ electric heating drying oven and let it stand for 4 hours to make the solution gel. Demold to obtain temperature-responsive smart adhesive gelatin-based conductive hydrogel.

[0049] Tests showed that the hydrogel prepared in Example 1 had a fracture strain of approximately 820%, a fracture stress of approximately 0.25 MPa, a fracture energy of 42 J / m², an adhesion strength of 9.2 kPa, an electrical conductivity of 13.2 S / m, and an equilibrium swelling ratio of approximately 210%.

[0050] Example 2

[0051] In this embodiment, the total mass of the hydrogel raw material is 11.5655 g, and the mass fraction of each component is as follows: GelMA 8.65 wt%, PGA aqueous solution 17.29 wt%, PEDOT:SCS-SH dispersion 3.46 wt%, APS 1.73 wt%, TEMED 0.13 wt%, and deionized water 68.74 wt%.

[0052] Step S1: In a 60℃ water bath, take 8.0g of deionized water and place it in a beaker. Add 1.0g of GelMA and stir until completely dissolved. After cooling to room temperature, add 2.0g of 1% PGA aqueous solution and stir to mix evenly.

[0053] Step S2: Add 0.4g of 5% PEDOT:SCS-SH dispersion to the solution obtained in step S1, stir to disperse it fully, then add 0.2g of APS and 0.0155g of TEMED in sequence, stir to mix evenly, remove air bubbles by ultrasonication, and pour into a mold.

[0054] Step S3: Place the above pregel mixed solution into a 40℃ electric heating drying oven and let it stand for 4 hours to make the solution gel. Demold to obtain temperature-responsive smart adhesive gelatin-based conductive hydrogel.

[0055] Tests showed that the hydrogel prepared in Example 2 had a low crosslinking density, a fracture strain of about 600%, a fracture stress of about 0.15 MPa, and an equilibrium swelling rate of about 400%.

[0056] Example 3

[0057] In this embodiment, the total mass of the hydrogel raw material is 11.8155 g, and the mass fraction of each component is as follows: GelMA 10.58 wt%, PGA aqueous solution 16.93 wt%, PEDOT:SCS-SH dispersion 3.39 wt%, APS 1.69 wt%, TEMED 0.13 wt%, and deionized water 67.28 wt%.

[0058] Step S1: In a 60℃ water bath, take 8.0g of deionized water and place it in a beaker. Add 1.25g of GelMA and stir until completely dissolved. After cooling to room temperature, add 2.0g of 1% PGA aqueous solution and stir to mix evenly.

[0059] Step S2: Add 0.4g of 5% PEDOT:SCS-SH dispersion to the solution obtained in step S1, stir to disperse it fully, then add 0.2g of APS and 0.0155g of TEMED in sequence, stir to mix evenly, remove air bubbles by ultrasonication, and pour into a mold.

[0060] Step S3: Place the above pregel mixed solution into a 40℃ electric heating drying oven and let it stand for 4 hours to make the solution gel. Demold to obtain temperature-responsive smart adhesive gelatin-based conductive hydrogel.

[0061] Tests showed that the hydrogel prepared in Example 3 had a fracture strain of approximately 700%, a fracture stress of approximately 0.18 MPa, and an equilibrium swelling ratio of approximately 320%.

[0062] Example 4

[0063] In this embodiment, the total mass of the hydrogel raw material is 12.4155g, and the mass fraction of each component is as follows: GelMA 14.10wt%, PGA aqueous solution 16.11wt%, PEDOT:SCS-SH dispersion 3.22wt%, APS 1.61wt%, TEMED 0.12wt%, and deionized water 64.84wt%.

[0064] Step S1: In a 60℃ water bath, take 8.0g of deionized water and place it in a beaker. Add 1.75g ​​of GelMA and stir until completely dissolved. After cooling to room temperature, add 2.0g of 1% PGA aqueous solution and stir to mix evenly.

[0065] Step S2: Add 0.4g of 5% PEDOT:SCS-SH dispersion to the solution obtained in step S1, stir to disperse it fully, then add 0.2g of APS and 0.0155g of TEMED in sequence, stir to mix evenly, remove air bubbles by ultrasonication, and pour into a mold.

[0066] Step S3: Place the above pregel mixed solution into a 40℃ electric heating drying oven and let it stand for 4 hours to make the solution gel. Demold to obtain temperature-responsive smart adhesive gelatin-based conductive hydrogel.

[0067] Tests showed that the hydrogel prepared in Example 4 had a high crosslinking density, a fracture strain of approximately 650%, a fracture stress of approximately 0.28 MPa, and an equilibrium swelling rate of approximately 230%.

[0068] Example 5

[0069] In this embodiment, the total mass of the hydrogel raw material is 12.7155 g, and the mass fraction of each component is as follows: GelMA 15.73 wt%, PGA aqueous solution 15.73 wt%, PEDOT:SCS-SH dispersion 3.15 wt%, APS 1.57 wt%, TEMED 0.12 wt%, and deionized water 63.70 wt%.

[0070] Step S1: In a 60℃ water bath, take 8.0g of deionized water and place it in a beaker. Add 2.0g of GelMA and stir until completely dissolved. After cooling to room temperature, add 2.0g of 1% PGA aqueous solution and stir to mix evenly.

[0071] Step S2: Add 0.4g of 5% PEDOT:SCS-SH dispersion to the solution obtained in step S1, stir to disperse it fully, then add 0.2g of APS and 0.0155g of TEMED in sequence, stir to mix evenly, remove air bubbles by ultrasonication, and pour into a mold.

[0072] Step S3: Place the above pregel mixed solution into a 40℃ electric heating drying oven and let it stand for 4 hours to make the solution gel. Demold to obtain temperature-responsive smart adhesive gelatin-based conductive hydrogel.

[0073] Testing revealed that the hydrogel prepared in Example 5 had an excessively high crosslinking density and an overly dense network, with a fracture strain of approximately 550%, resulting in decreased material toughness and brittle fracture. The equilibrium swelling rate was approximately 200%.

[0074] Example 6

[0075] In this embodiment, the total mass of the hydrogel raw material is 11.6155 g, and the mass fraction of each component is as follows: GelMA 12.91 wt%, PGA aqueous solution 12.91 wt%, PEDOT:SCS-SH dispersion 3.44 wt%, APS 1.72 wt%, TEMED 0.13 wt%, and deionized water 68.88 wt%.

[0076] Step S1: In a 60℃ water bath, take 8.0g of deionized water and place it in a beaker. Add 1.5g of GelMA and stir until completely dissolved. After cooling to room temperature, add 1.5g of 1% PGA aqueous solution and stir to mix evenly.

[0077] Step S2: Add 0.4g of 5% PEDOT:SCS-SH dispersion to the solution obtained in step S1, stir to disperse it fully, then add 0.2g of APS and 0.0155g of TEMED in sequence, stir to mix evenly, remove air bubbles by ultrasonication, and pour into a mold.

[0078] Step S3: Place the above pregel mixed solution into a 40℃ electric heating drying oven and let it stand for 4 hours to make the solution gel. Demold to obtain temperature-responsive smart adhesive gelatin-based conductive hydrogel.

[0079] The hydrogel prepared in Example 6 was tested and found to have an adhesion strength of about 5.3 kPa, a fracture energy of about 36 J / m², and a fracture strain of about 600%.

[0080] Example 7

[0081] In this embodiment, the total mass of the hydrogel raw material is 12.6155 g, and the mass fraction of each component is as follows: GelMA 11.89 wt%, PGA aqueous solution 19.82 wt%, PEDOT:SCS-SH dispersion 3.17 wt%, APS 1.59 wt%, TEMED 0.12 wt%, and deionized water 63.41 wt%.

[0082] Step S1: In a 60℃ water bath, take 8.0g of deionized water and place it in a beaker. Add 1.5g of GelMA and stir until completely dissolved. After cooling to room temperature, add 2.5g of 1% PGA aqueous solution and stir to mix evenly.

[0083] Step S2: Add 0.4g of 5% PEDOT:SCS-SH dispersion to the solution obtained in step S1, stir to disperse it fully, then add 0.2g of APS and 0.0155g of TEMED in sequence, stir to mix evenly, remove air bubbles by ultrasonication, and pour into a mold.

[0084] Step S3: Place the above pregel mixed solution into a 40℃ electric heating drying oven and let it stand for 4 hours to make the solution gel. Demold to obtain temperature-responsive adhesive smart gelatin-based conductive hydrogel.

[0085] The hydrogel prepared in Example 7 was tested and found to have an adhesion strength of about 8.1 kPa, a fracture energy of about 39 J / m², and a fracture strain of about 750%.

[0086] Example 8

[0087] In this embodiment, the total mass of the hydrogel raw material is 13.1155 g, and the mass fraction of each component is as follows: GelMA 11.44 wt%, PGA aqueous solution 22.88 wt%, PEDOT:SCS-SH dispersion 3.05 wt%, APS 1.53 wt%, TEMED 0.12 wt%, and deionized water 60.99 wt%.

[0088] Step S1: In a 60℃ water bath, take 8.0g of deionized water and place it in a beaker. Add 1.5g of GelMA and stir until completely dissolved. After cooling to room temperature, add 3.0g of 1% PGA aqueous solution and stir to mix evenly.

[0089] Step S2: Add 0.4g of 5% PEDOT:SCS-SH dispersion to the solution obtained in step S1, stir to disperse it fully, then add 0.2g of APS and 0.0155g of TEMED in sequence, stir to mix evenly, remove air bubbles by ultrasonication, and pour into a mold.

[0090] Step S3: Place the above pregel mixed solution into a 40℃ electric heating drying oven and let it stand for 4 hours to make the solution gel. Demold to obtain temperature-responsive smart adhesive gelatin-based conductive hydrogel.

[0091] Tests showed that the hydrogel prepared in Example 8 had an adhesion strength of about 7.9 kPa and a fracture energy of about 37 J / m². Excessive PGA resulted in a loose network and decreased crosslinking uniformity, leading to a reduction in performance compared to Example 1.

[0092] Comparative Example 1

[0093] In this embodiment, the total mass of the hydrogel raw material is 10.2155g, and the mass fraction of each component is as follows: GelMA 14.68wt%, PEDOT:SCS-SH dispersion 3.95wt%, APS 1.96wt%, TEMED 0.15wt%, and deionized water 79.09wt%.

[0094] Step S1: In a 60℃ water bath, take 8.0g of deionized water and place it in a beaker. Add 1.5g of GelMA, stir until completely dissolved, and cool to room temperature.

[0095] Step S2: Add 0.4g of 5% PEDOT:SCS-SH dispersion to the solution obtained in step S1, stir to disperse it fully, then add 0.2g of APS and 0.0155g of TEMED in sequence, stir to mix evenly, remove air bubbles by ultrasonication, and pour into a mold.

[0096] Step S3: Place the above pregel mixed solution into a 40℃ electric heating drying oven and let it stand for 4 hours to allow the solution to gel. Demold to obtain gelatin-based conductive hydrogel.

[0097] Tests showed that the hydrogel prepared in Comparative Example 1 had an adhesion strength of only 2.1 kPa, a fracture energy of 31 J / m², and a fracture strain of approximately 500%, indicating that it did not possess practical adhesion capabilities.

[0098] Comparative Example 2

[0099] The total mass of the hydrogel raw material in this comparative example is 11.7155 g, and the mass fraction of each component is as follows: GelMA 12.80 wt%, PGA aqueous solution 17.07 wt%, APS 1.71 wt%, TEMED 0.13 wt%, and deionized water 68.29 wt%.

[0100] Step S1: In a 60℃ water bath, take 8.0g of deionized water and place it in a beaker. Add 1.5g of GelMA and stir until completely dissolved. After cooling to room temperature, add 2.0g of 1% PGA aqueous solution and stir to mix evenly.

[0101] Step S2: Add 0.2g of APS and 0.0155g of TEMED to the solution obtained in step S1, stir and mix evenly, remove air bubbles by sonication, and then pour into a mold;

[0102] Step S3: Place the above pregel mixed solution in a 40℃ electric heating drying oven and let it stand for 4 hours to allow the solution to gel. Demold to obtain gelatin-based hydrogel without conductive components.

[0103] Tests showed that the hydrogel prepared in Comparative Example 2 had a conductivity of only 0.025 S / m, which does not possess practical electrical conductivity.

[0104] The foregoing has shown and described the basic principles, main features and advantages of the present invention. Various changes and modifications can be made to the present invention without departing from the spirit and scope thereof, and all such changes and modifications fall within the scope of the present invention as claimed.

Claims

1. A method for preparing a temperature-responsive smart adhesive gelatin-based conductive hydrogel, characterized in that: A temperature-responsive smart adhesive gelatin-based conductive hydrogel was prepared using methacrylamide gelatin as the backbone, polymerized gallic acid as the structure-regulating component, and PEDOT:SCS-SH as the conductive unit via an ammonium persulfate / tetramethylethylenediamine crosslinking system. The specific preparation steps are as follows: Step S1: Dissolve gelatin in PBS buffer, add methacrylic anhydride and react at 40-70°C to obtain methacrylamide gelatin. Then, dilute with PBS buffer to terminate the reaction, dialyze and freeze dry to obtain solid methacrylamide gelatin. Step S2: Dissolve gallic acid in deionized water, then add alkaline solution to adjust the pH of the mixture to 7-9, and then react in air to obtain polymerized gallic acid solution; Step S3: Chitosan is dissolved in acetic acid solution, and 1,3-propanesulfonyl lactone is added under nitrogen protection and stirred to react. The reaction solution is precipitated in cold acetone, washed with methanol, and then vacuum dried to obtain SCS. SCS is dispersed in deionized water, and HOBt, N-acetyl-L-cysteine, and EDC·HCl are added and stirred to react at room temperature. The reaction solution is dialyzed and then freeze-dried to obtain SCS-SH. SCS-SH and EDOT monomer are dissolved in a water / ethanol mixed solvent, and ammonium persulfate solution is added and stirred to react. The reaction product is washed with water and ethanol by centrifugation, and then vacuum dried to obtain solid powder PEDOT:SCS-SH. The obtained solid powder is dissolved in deionized water to obtain PEDOT:SCS-SH dispersion. Step S4: At 40~80℃, dissolve methacrylamide gelatin in deionized water, cool to room temperature, add polymeric gallic acid aqueous solution and stir to mix evenly to obtain a mixed solution, then add PEDOT:SCS-SH dispersion to the mixed solution and continue stirring until uniformly dispersed, then add initiator ammonium persulfate and catalyst tetramethylethylenediamine in sequence and stir thoroughly to remove bubbles until the solution presents a uniform and stable reaction system; Step S5: Pour the mixed solution obtained in step S4 into a mold and gelatinize it at 30~50℃, then demold to obtain a temperature-responsive smart adhesive gelatin-based conductive hydrogel.

2. The method for preparing the temperature-responsive smart adhesive gelatin-based conductive hydrogel according to claim 1, characterized in that: The mass ratio of gelatin to methacrylic anhydride in step S1 is 5:(3.5~4.5).

3. The method for preparing the temperature-responsive smart adhesive gelatin-based conductive hydrogel according to claim 1, characterized in that: The mass fraction of the polymerized gallic acid solution in step S2 is 0.5%~1.5%.

4. The method for preparing the temperature-responsive smart adhesive gelatin-based conductive hydrogel according to claim 1, characterized in that: The mass fraction of the PEDOT:SCS-SH dispersion in step S3 is 4%~6%.

5. The method for preparing the temperature-responsive smart adhesive gelatin-based conductive hydrogel according to claim 1, characterized in that: In step S4, the polymeric gallic acid aqueous solution accounts for 10% to 20% of the total mass of the hydrogel, the PEDOT:SCS-SH dispersion accounts for 1% to 5% of the total mass of the hydrogel, the initiator ammonium persulfate accounts for 1% to 2% of the total mass of the hydrogel, the catalyst tetramethylethylenediamine accounts for 0.02% to 0.2% of the total mass of the hydrogel, the amount of deionized water accounts for 40% to 80% of the total mass of the hydrogel, and the amount of methacrylated gelatin accounts for 5% to 15% of the total mass of the hydrogel.

6. A temperature-responsive smart adhesive gelatin-based conductive hydrogel, characterized in that... The hydrogel is prepared by the method described in any one of claims 1 to 5. The hydrogel uses methacrylamide gelatin as the main skeleton component, polymeric gallic acid as the temperature-responsive functional component, and PEDOT:SCS-SH as the conductive unit. In an aqueous system, it is constructed by in-situ free radical polymerization under the initiation of ammonium persulfate / tetramethylethylenediamine to form a multi-linked network structure. The methacrylamide gelatin forms a continuous chemical covalent cross-linked network as the main skeleton. The polymeric gallic acid interacts with the skeleton network through dynamic hydrogen bonds, which endows the material with temperature-dependent adhesion regulation characteristics. PEDOT:SCS-SH is embedded in the system to form an electron-ion synergistic conductive pathway. This makes the hydrogel have excellent fracture resistance, temperature-responsive adhesion, precisely controllable swelling performance, excellent conductivity and cycle stability, and has the sensing performance of rapid mechanical deformation.

7. The application of the temperature-responsive smart adhesive gelatin-based conductive hydrogel of claim 6 as an adhesive material for wearable electronic devices, flexible sensors, or biointerfaces.

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