An amino-modified MXene-enhanced gelatin / chitosan composite hydrogel and its preparation method

Abstract

The present invention discloses an amino-modified MXene-enhanced gelatin / chitosan composite hydrogel and a preparation method thereof. The main preparation process comprises: using amino-modified MXene as a conductive filler and reinforcing agent for the hydrogel and citrate as a crosslinker, the amino-modified MXene-enhanced gelatin / chitosan composite hydrogel is prepared through a one-pot method and a salting-out process. The amino-modified MXene-enhanced gelatin / chitosan composite hydrogel prepared by this method has excellent mechanical and conductive properties. The citrate-enhanced crosslinker tightly binds the amino-modified MXene to the gelatin and chitosan molecular chains through ionic crosslinking with the amino groups, and is evenly and stably distributed in the hydrogel matrix. This allows the inorganic interface to transfer loads under the action of external forces, and further, combined with the salting-out effect of the polymer molecular chains, produces a physically enhanced amino-modified MXene-enhanced gelatin / chitosan composite hydrogel. Furthermore, the presence of the amino-modified MXene and a large number of free ions imparts excellent conductive and sensing properties to the hydrogel.

Description

Technical Field

[0001] The present invention belongs to the field of intelligent hydrogel products and flexible electronic technologies, and specifically relates to an amino-modified MXene-enhanced gelatin / chitosan composite hydrogel and a preparation method thereof. Background Art

[0002] Conductive hydrogels possess three-dimensional cross-linked networks, excellent biocompatibility, and unique mechanical properties. Their unique network structure and high hydrophilicity provide space for a large number of water molecules (bound water fixed to the polymer chains and free water filling the gaps between the polymer chains), making both the network structure and mechanical properties of conductive hydrogels tunable. In recent years, significant progress has been made in human-machine interfaces, soft robotics, wearable sensors, and other areas. Currently, conductive hydrogels are often synthesized using petroleum products such as polyacrylic acid and polyacrylamide as raw materials. Although these hydrogels have good performance, they are difficult to degrade and can cause irreversible pollution and damage to the ecological environment. Considering that flexible electronic products may become essential products that change human lifestyles in the future, when constructing high-performance flexible electronic products, attention must be paid to the green environmental protection and sustainability of raw materials to achieve the sustainable development of flexible electronic technology.

[0003] In recent years, biomass resources have been favored by more and more researchers as a highly promising renewable resource. At present, biomass resources account for 14% of the world's energy consumption and are another major energy source after fossil energy, but their utilization rate is low and resource waste is serious. Therefore, the development and utilization of biomass resources are of great significance to achieving sustainable and healthy development. Biomass renewable resources (such as gelatin, chitosan, lignin, sodium alginate, starch, etc.) have a wide range of sources and good biocompatibility and biodegradability. Using them to replace petroleum processed products to prepare biomass-based conductive hydrogels is expected to obtain high-performance hydrogel products with excellent physical and chemical properties and biological properties, high water permeability, biocompatibility and biodegradability, and promote the development and application of biomass resources in the field of multifunctional hydrogel-based flexible electronics. However, due to the poor mechanical properties of biomass materials, the prepared hydrogels also have poor mechanical properties, which limits their application. Summary of the Invention

[0004] In order to overcome the shortcomings of the above-mentioned prior art, the object of the present invention is to provide an amino-modified MXene reinforced gelatin / chitosan composite hydrogel and a preparation method thereof, so as to solve the problem that the mechanical properties of biomass materials are poor, resulting in poor mechanical properties of biomass-based hydrogels.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] The present invention discloses a method for preparing an amino-modified MXene-enhanced gelatin / chitosan composite hydrogel, comprising the following steps:

[0007] 1) Add MXene to deionized water, disperse it evenly with ultrasound, add the modifier and catalyst, stir until completely dissolved, then heat and keep the reaction; after the reaction, centrifuge, wash, and freeze-dry the product to obtain amino-modified MXene;

[0008] 2) adding chitosan to deionized water, and adding acetic acid dropwise until the chitosan is completely dissolved to obtain a chitosan solution;

[0009] 3) Add the amino-modified MXene to deionized water and disperse it evenly by ultrasonication; add gelatin and stir until it is completely dissolved; add the chitosan solution dropwise, stir evenly, and ultrasonicate to obtain an amino-modified MXene-enhanced gelatin / chitosan composite hydrogel solution;

[0010] 4) The above solution is transferred into a mold and allowed to stand to obtain an amino-modified MXene-enhanced gelatin / chitosan composite pregel, and the composite pregel is then placed in a mixed solution containing citrate, a small molecule polyol, and deionized water for immersion to obtain an amino-modified MXene-enhanced gelatin / chitosan composite hydrogel.

[0011] Preferably, in step 1), the mass ratio of MXene, deionized water, modifier and catalyst is (0.5-1.5):25:(2.5-4.0):0.02;

[0012] The modifier is serine, lysine or arginine;

[0013] The catalyst is a mixture of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 4-dimethylaminopyridine, with a mass ratio of 1:1.

[0014] Preferably, in step 1), the temperature is raised to 100-120° C. and kept for reaction for 3-6 hours.

[0015] Preferably, in step 2), the mass ratio of chitosan to deionized water is 3:97.

[0016] Preferably, in step 3), the mass ratio of amino-modified MXene to deionized water is (0.097-0.538):35; the mass ratio of gelatin to chitosan solution is (3.521-9.086):(1.157-8.012).

[0017] Preferably, in step 4), the mass concentration of citrate is 15-50 wt%; and the cation of citrate is any one of sodium ion, iron ion and potassium ion.

[0018] Preferably, in step 4), the mass ratio of the small molecule polyol to deionized water is (20-250):(50-300).

[0019] Preferably, in step 4), the type of the small molecule polyol is any one of ethylene glycol, propylene glycol, dipropylene glycol, glycerol, dipropylene glycol, butanediol, pentanediol, and pentaerythritol.

[0020] Preferably, in step 4), the mixture is allowed to stand at 4° C. for 30 to 60 minutes; and the soaking time is 2 to 6 hours.

[0021] The present invention also discloses an amino-modified MXene-enhanced gelatin / chitosan composite hydrogel prepared by the above preparation method. The amino-modified MXene-enhanced gelatin / chitosan composite hydrogel has a tensile strength of 2.017 to 2.865 MPa, an elongation at break of 425.159 to 496.751%, and an electrical conductivity of 0.429 to 0.527 S / m.

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

[0023] This invention discloses a method for preparing an amino-modified MXene-reinforced gelatin / chitosan composite hydrogel. Using amino-modified MXene as the hydrogel's conductive filler and reinforcing agent, and citrate as a crosslinker, the amino-modified MXene-reinforced gelatin / chitosan composite hydrogel with excellent mechanical and conductive properties is prepared using a one-pot method and salting-out process. First, given gelatin's temperature-sensitive properties, the composite hydrogel forms a single gelatin crosslinked network at low temperatures. Subsequently, the hydrogel is immersed in a citrate solution, where ionic crosslinking produces the amino-modified MXene-reinforced gelatin / chitosan composite hydrogel. The performance enhancement mechanism is as follows: (1) During the immersion process, a large amount of citrate ions and metal ions diffuse into the hydrogel driven by the concentration difference. Citrate acts as a crosslinker and tightly binds the amino-modified MXene to the gelatin and chitosan molecular chains through ionic crosslinking with the amino groups, thereby enhancing the mechanical properties of gelatin and chitosan. It is evenly and stably distributed in the hydrogel matrix, thereby utilizing the inorganic interface to transfer load under the action of external force, and producing a physically enhanced amino-modified MXene-enhanced gelatin / chitosan composite hydrogel. That is, the amino-modified MXene can change the stress field and stress concentration in the hydrogel matrix, thereby enhancing the composite hydrogel's ability to absorb impact and resist crack propagation. When the composite hydrogel is stretched by external force, the two ends of the amino-modified MXene are subjected to tensile stress from the hydrogel matrix, while the middle is subjected to compressive stress. Due to the interaction of forces, yielding is favored, which manifests as enhanced toughness. In addition, because the amino-modified MXene has a large specific surface area and is tightly bound to the polymer chains in the hydrogel matrix, it has a large contact area with the matrix. When the composite hydrogel is impacted, more microcracks will be generated, absorbing more impact energy, thereby achieving a simultaneous strengthening and toughening effect, thereby improving the mechanical properties of the composite hydrogel. (2) The gelatin and chitosan molecular chains aggregate due to the salting-out effect, forming a hydrophobic interchain interaction region, which increases the cross-linking density of the hydrogel network and enhances its mechanical properties. (3) The presence of amino-modified MXene and a large number of free ions gives the composite hydrogel good electrical conductivity and sensing properties.

[0024] The reaction is then maintained at 100-120°C for 3-6 hours. The hydroxyl groups on the MXene surface react with the carboxyl groups in the modifier to form an esterification reaction, yielding amino-modified MXene. Appropriate reaction conditions are crucial for a successful esterification reaction. Too low a temperature can hinder the esterification reaction by failing to generate the necessary heat. Excessively high temperatures can lead to side reactions, producing impurities such as ethers.

[0025] Furthermore, the mixture was allowed to stand at 4°C for 30 to 60 minutes. During this process, the unique thermosensitive properties of gelatin caused hydrogen bonds between its molecular chains to form a triple helix structure as a connecting region, forming a single gelatin cross-linked network, thereby obtaining an amino-modified MXene-enhanced gelatin / chitosan composite hydrogel pregel.

[0026] Furthermore, the mass concentration of citrate is 15-50wt%. Sodium citrate serves as an inorganic salt and crosslinking agent, and its dosage determines the mechanical and conductive properties of the amino-modified MXene-enhanced gelatin / chitosan composite hydrogel. Appropriate concentration is key to ensuring that the amino-modified MXene-enhanced gelatin / chitosan composite hydrogel possesses both high mechanical and high conductive properties. When the mass concentration of sodium citrate is low, the number of citrate ions and sodium ions that can enter the hydrogel during immersion is limited, resulting in weak crosslinking and salting-out, which in turn limits the performance improvement of the hydrogel. Excessive sodium citrate, on the other hand, can increase the crosslinking density of the polymer molecular chains in the hydrogel through crosslinking and salting-out, thereby affecting the conductive and mechanical properties of the hydrogel.

[0027] The amino-modified MXene-enhanced gelatin / chitosan composite hydrogel prepared by the present invention has excellent mechanical properties, conductive properties and sensing properties. Its tensile strength and elongation at break can reach 2.865 MPa and 496.751% respectively, and its conductivity can reach 0.527 S / m. It can produce significant current changes under the action of external force. In addition, the amino-modified MXene-enhanced gelatin / chitosan composite hydrogel has excellent biocompatibility and biodegradability, which is of great significance for promoting the green development of flexible electronics. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 FT-IR spectrum of the amino-modified MXene prepared in Example 1 of the present invention;

[0029] Figure 2 This is a graph showing the mechanical properties of the amino-modified MXene-enhanced gelatin / chitosan composite hydrogel prepared in Example 1 of the present invention;

[0030] Figure 3 This is a test diagram of the sensing performance of the amino-modified MXene-enhanced gelatin / chitosan composite hydrogel prepared in Example 1 of the present invention under pressure. DETAILED DESCRIPTION

[0031] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0032] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0033] A method for preparing an amino-modified MXene-enhanced gelatin / chitosan composite hydrogel, comprising the following specific steps:

[0034] (1) 1.6 g of lithium fluoride was added to 20 mL of 9 mol / L hydrochloric acid and stirred until the lithium fluoride was completely dissolved. Subsequently, 1 g of titanium aluminum carbide was slowly added thereto and stirred at 35°C for 48 h. After the reaction was completed, the mixture was centrifuged and washed with deionized water until the pH value of the supernatant reached 6. The product at the bottom of the centrifuge tube was collected and freeze-dried to obtain MXene (Ti3C2Tx);

[0035] (2) 0.5-1.5 g of MXene was added to 25 g of deionized water and ultrasonically dispersed uniformly; 2.5-4.0 g of a modifier (the type of modifier is any one of serine, lysine, and arginine), 0.01 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, and 0.01 g of 4-dimethylaminopyridine were added to the above dispersion, and stirred under a nitrogen atmosphere until completely dissolved, and then heated to 100-120 ° C and kept warm for 3-6 h; after the reaction, the product was centrifuged and washed with deionized water 3-5 times, and freeze-dried to obtain amino-modified MXene;

[0036] (3) 3 g of chitosan was added to 97 g of deionized water, and acetic acid was then added dropwise with stirring until the chitosan was completely dissolved to obtain a 3 wt% chitosan solution;

[0037] (4) 0.097-0.538 g of amino-modified MXene was added to 35 g of deionized water and dispersed uniformly by ultrasonication; 3.521-9.086 g of gelatin was added thereto and stirred at 60 °C until completely dissolved; 1.157-8.012 g of chitosan solution was then added dropwise and stirred uniformly, and bubbles were removed by ultrasonication to obtain an amino-modified MXene-enhanced gelatin / chitosan composite hydrogel solution;

[0038] (5) The above solution was transferred to a mold and allowed to stand at 4°C for 30 to 60 minutes to obtain an amino-modified MXene-enhanced gelatin / chitosan composite pregel, which was then placed in a mixed solution containing 15 to 50 wt% citrate (the cation type of citrate is any one of sodium ion, iron ion, and potassium ion), 20 to 250 g of a small molecule polyol (the type of the small molecule polyol is any one of ethylene glycol, propylene glycol, dipropylene glycol, glycerol, dipropylene glycol, butanediol, pentanediol, and pentaerythritol) and 50 to 300 g of deionized water, and soaked for 2 to 6 hours to obtain an amino-modified MXene-enhanced gelatin / chitosan composite hydrogel.

[0039] Example 1:

[0040] (1) 1.5 g of MXene was added to 25 g of deionized water and ultrasonically dispersed uniformly; 2.5 g of serine, 0.01 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 0.01 g of 4-dimethylaminopyridine were added to the above dispersion and stirred under a nitrogen atmosphere until completely dissolved, then heated to 105 ° C and kept warm for 6 h; after the reaction, the product was centrifuged and washed with deionized water 5 times, and freeze-dried to obtain amino-modified MXene;

[0041] (2) 3 g of chitosan was added to 97 g of deionized water, and acetic acid was then added dropwise with stirring until the chitosan was completely dissolved to obtain a 3 wt% chitosan solution;

[0042] (3) 0.097 g of amino-modified MXene was added to 35 g of deionized water and dispersed uniformly by ultrasonication; 3.521 g of gelatin was added thereto and stirred at 60 °C until completely dissolved; 5.264 g of chitosan solution was then added dropwise and stirred uniformly, and bubbles were removed by ultrasonication to obtain an amino-modified MXene-enhanced gelatin / chitosan composite hydrogel solution;

[0043] (4) The above solution was transferred to a mold and allowed to stand at 4°C for 35 min to obtain an amino-modified MXene-enhanced gelatin / chitosan composite pregel, which was then placed in a mixed solution containing 50 wt% sodium citrate, 100 g dipropylene glycol, and 100 g deionized water and soaked for 4 h to obtain an amino-modified MXene-enhanced gelatin / chitosan composite hydrogel.

[0044] Example 2:

[0045] (1) 0.7 g of MXene was added to 25 g of deionized water and ultrasonically dispersed uniformly; 3.7 g of lysine, 0.01 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 0.01 g of 4-dimethylaminopyridine were added to the above dispersion and stirred under a nitrogen atmosphere until completely dissolved, then heated to 120 °C and kept warm for 5 h; after the reaction, the product was centrifuged and washed with deionized water three times, and freeze-dried to obtain amino-modified MXene;

[0046] (2) 3 g of chitosan was added to 97 g of deionized water, and acetic acid was then added dropwise with stirring until the chitosan was completely dissolved to obtain a 3 wt% chitosan solution;

[0047] (3) 0.152 g of amino-modified MXene was added to 35 g of deionized water and dispersed uniformly by ultrasonication; 8.569 g of gelatin was added thereto and stirred at 60 °C until completely dissolved; 2.395 g of chitosan solution was then added dropwise and stirred uniformly, and bubbles were removed by ultrasonication to obtain an amino-modified MXene-enhanced gelatin / chitosan composite hydrogel solution;

[0048] (4) The above solution was transferred to a mold and allowed to stand at 4°C for 30 min to obtain an amino-modified MXene-enhanced gelatin / chitosan composite pregel, which was then placed in a mixed solution containing 25 wt% ferric citrate, 20 g pentanediol, and 50 g deionized water and soaked for 5 h to obtain an amino-modified MXene-enhanced gelatin / chitosan composite hydrogel.

[0049] Example 3:

[0050] (1) 1.2 g of MXene was added to 25 g of deionized water and ultrasonically dispersed uniformly; 3.2 g of lysine, 0.01 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 0.01 g of 4-dimethylaminopyridine were added to the above dispersion and stirred under a nitrogen atmosphere until completely dissolved, then the temperature was raised to 112 ° C and kept warm for 6 h; after the reaction, the product was centrifuged and washed with deionized water 4 times, and freeze-dried to obtain amino-modified MXene;

[0051] (2) 3 g of chitosan was added to 97 g of deionized water, and acetic acid was then added dropwise with stirring until the chitosan was completely dissolved to obtain a 3 wt% chitosan solution;

[0052] (3) 0.099 g of amino-modified MXene was added to 35 g of deionized water and dispersed uniformly by ultrasonication; 4.621 g of gelatin was added thereto and stirred at 60 °C until completely dissolved; 8.012 g of chitosan solution was then added dropwise and stirred uniformly, and bubbles were removed by ultrasonication to obtain an amino-modified MXene-enhanced gelatin / chitosan composite hydrogel solution;

[0053] (4) The above solution was transferred to a mold and allowed to stand at 4°C for 50 min to obtain an amino-modified MXene-enhanced gelatin / chitosan composite pregel, which was then placed in a mixed solution containing 30 wt% sodium citrate, 250 g propylene glycol, and 300 g deionized water and soaked for 2 h to obtain an amino-modified MXene-enhanced gelatin / chitosan composite hydrogel.

[0054] Example 4:

[0055] (1) 0.5 g of MXene was added to 25 g of deionized water and ultrasonically dispersed uniformly; 2.7 g of arginine, 0.01 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 0.01 g of 4-dimethylaminopyridine were added to the above dispersion and stirred under a nitrogen atmosphere until completely dissolved, then the temperature was raised to 103 ° C and kept warm for 4 h; after the reaction, the product was centrifuged and washed with deionized water three times, and freeze-dried to obtain amino-modified MXene;

[0056] (2) 3 g of chitosan was added to 97 g of deionized water, and acetic acid was then added dropwise with stirring until the chitosan was completely dissolved to obtain a 3 wt% chitosan solution;

[0057] (3) 0.538 g of amino-modified MXene was added to 35 g of deionized water and dispersed uniformly by ultrasonication; 9.086 g of gelatin was added thereto and stirred at 60 °C until completely dissolved; 3.942 g of chitosan solution was then added dropwise and stirred uniformly, and bubbles were removed by ultrasonication to obtain an amino-modified MXene-enhanced gelatin / chitosan composite hydrogel solution;

[0058] (4) The above solution was transferred to a mold and allowed to stand at 4°C for 60 min to obtain an amino-modified MXene-enhanced gelatin / chitosan composite pregel, which was then placed in a mixed solution containing 15 wt% potassium citrate, 150 g ethylene glycol, and 100 g deionized water and soaked for 3 h to obtain an amino-modified MXene-enhanced gelatin / chitosan composite hydrogel.

[0059] Example 5:

[0060] (1) 0.9 g of MXene was added to 25 g of deionized water and ultrasonically dispersed uniformly; 3.5 g of serine, 0.01 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, and 0.01 g of 4-dimethylaminopyridine were added to the above dispersion and stirred under a nitrogen atmosphere until completely dissolved. The mixture was then heated to 100 °C and kept warm for 5 h. After the reaction, the product was centrifuged and washed with deionized water three times, and freeze-dried to obtain amino-modified MXene.

[0061] (2) 3 g of chitosan was added to 97 g of deionized water, and acetic acid was then added dropwise with stirring until the chitosan was completely dissolved to obtain a 3 wt% chitosan solution;

[0062] (3) 0.481 g of amino-modified MXene was added to 35 g of deionized water and dispersed uniformly by ultrasonication; 7.485 g of gelatin was added thereto and stirred at 60 °C until completely dissolved; 1.157 g of chitosan solution was then added dropwise and stirred uniformly, and bubbles were removed by ultrasonication to obtain an amino-modified MXene-enhanced gelatin / chitosan composite hydrogel solution;

[0063] (4) The above solution was transferred to a mold and allowed to stand at 4°C for 45 min to obtain an amino-modified MXene-enhanced gelatin / chitosan composite pregel, which was then placed in a mixed solution containing 20 wt% potassium citrate, 100 g pentaerythritol, and 200 g deionized water and soaked for 6 h to obtain an amino-modified MXene-enhanced gelatin / chitosan composite hydrogel.

[0064] Example 6:

[0065] (1) 1.4 g of MXene was added to 25 g of deionized water and ultrasonically dispersed uniformly; 4.0 g of arginine, 0.01 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 0.01 g of 4-dimethylaminopyridine were added to the above dispersion and stirred under a nitrogen atmosphere until completely dissolved, then heated to 117 ° C and kept warm for 3 h; after the reaction, the product was centrifuged and washed with deionized water 5 times, and freeze-dried to obtain amino-modified MXene;

[0066] (2) 3 g of chitosan was added to 97 g of deionized water, and acetic acid was then added dropwise with stirring until the chitosan was completely dissolved to obtain a 3 wt% chitosan solution;

[0067] (3) 0.237 g of amino-modified MXene was added to 35 g of deionized water and dispersed uniformly by ultrasonication; 8.294 g of gelatin was added thereto and stirred at 60 °C until completely dissolved; 2.268 g of chitosan solution was then added dropwise and stirred uniformly, and bubbles were removed by ultrasonication to obtain an amino-modified MXene-enhanced gelatin / chitosan composite hydrogel solution;

[0068] (4) The above solution was transferred to a mold and allowed to stand at 4°C for 30 min to obtain an amino-modified MXene-enhanced gelatin / chitosan composite pregel, which was then placed in a mixed solution containing 45 wt% ferric citrate, 180 g propylene glycol, and 200 g deionized water and soaked for 5 h to obtain an amino-modified MXene-enhanced gelatin / chitosan composite hydrogel.

[0069] Table 1 shows the properties of the amino-modified MXene-enhanced gelatin / chitosan composite hydrogel prepared in the above examples. From Table 1, it can be seen that the amino-modified MXene-enhanced gelatin / chitosan composite hydrogel prepared in the present invention has excellent mechanical properties, with a maximum tensile strength of 2.865 MPa and a maximum elongation at break of 496.751%. It also has good electrical conductivity and can light up a small light bulb. Taking Example 1 as an example, the infrared spectrum of the amino-modified MXene prepared therein shows Figure 1 As shown, it can be seen that the original MXene -1 There is an obvious characteristic peak at 1778cm, corresponding to the Ti-O bond; while the amino-modified MXene prepared in Example 1 of the present invention has a peak at 1778cm -1 C=O stretching vibration at 1332cm -1 and 941cm -1 The COC stretching vibration at 1622 cm indicates that the esterification reaction between the carboxyl group of serine and the hydroxyl group of MXene is successful. -1 NH bending vibration at 1243 cm -1 The CN stretching vibrations at show that the surface of the modified MXene contains amino groups. Figure 2 The mechanical properties of the amino-modified MXene-enhanced gelatin / chitosan composite hydrogel prepared in Example 1 are significantly improved compared with the gelatin / chitosan composite hydrogel and the MXene-enhanced gelatin / chitosan composite hydrogel, both the tensile strength and the elongation at break are significantly improved, indicating that the method of the present invention can significantly improve the mechanical properties of the hydrogel. Figure 3 The sensing performance of the amino-modified MXene-enhanced gelatin / chitosan composite hydrogel prepared in Example 1 under pressure shows that the amino-modified MXene-enhanced gelatin / chitosan composite hydrogel can produce obvious current changes under pressure, thereby realizing the sensing ability to external force.

[0070] Table 1 Properties of amino-modified MXene-enhanced gelatin / chitosan composite hydrogels

[0071]

[0072] The above content is only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing an amino-modified MXene-enhanced gelatin / chitosan composite hydrogel, characterized in that: The following steps are involved: 1) Add MXene to deionized water, disperse it evenly with ultrasound, add the modifier and catalyst, stir until completely dissolved, then heat and keep the reaction; after the reaction, centrifuge, wash, and freeze-dry the product to obtain amino-modified MXene; 2) Add chitosan to deionized water and add acetic acid dropwise until the chitosan is completely dissolved to obtain a chitosan solution; 3) Add amino-modified MXene to deionized water and disperse it evenly by ultrasonication; add gelatin and stir until it is completely dissolved; add chitosan solution dropwise, stir evenly, and ultrasonicate to obtain amino-modified MXene-enhanced gelatin / chitosan composite hydrogel solution; 4) The above solution is transferred into a mold and allowed to stand to obtain an amino-modified MXene-enhanced gelatin / chitosan composite pregel. The composite pregel is then placed in a mixed solution containing citrate, a small molecule polyol, and deionized water for immersion to obtain an amino-modified MXene-enhanced gelatin / chitosan composite hydrogel. In step 1), the mass ratio of MXene, deionized water, modifier, and catalyst is (0.5-1.5):25:(2.5-4.0):0.02; the temperature is raised to 100-120°C and kept for 3-6 hours; the modifier is serine, lysine, or arginine; In step 2), the mass ratio of chitosan to deionized water is 3:97; In step 3), the mass ratio of amino-modified MXene to deionized water is (0.097-0.538):35; the mass ratio of gelatin to chitosan solution is (3.521-9.086):(1.157-8.012); In step 4), the mass concentration of citrate is 15-50 wt %; the mass ratio of small molecule polyol to deionized water is (20-250):(50-300); The amino-modified MXene-reinforced gelatin / chitosan composite hydrogel is used to prepare flexible electronics.

2. The amino-modified MXene-enhanced gelatin / chitosan composite hydrogel and its preparation method according to claim 1, characterized in that: In step 1), the catalyst is a mixture of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 4-dimethylaminopyridine, with a mass ratio of 1:

1.

3. The amino-modified MXene-enhanced gelatin / chitosan composite hydrogel and the preparation method thereof according to claim 1, characterized in that: In step 4), the type of the small molecule polyol is any one of ethylene glycol, propylene glycol, dipropylene glycol, glycerol, dipropylene glycol, butanediol, pentanediol, and pentaerythritol.

4. The amino-modified MXene-enhanced gelatin / chitosan composite hydrogel and the preparation method thereof according to claim 1, characterized in that: In step 4), let it stand at 4°C for 30 to 60 minutes; the soaking time is 2 to 6 hours.

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