A gelatin-based hydrogel and its preparation method and application

Abstract

The present invention discloses a gelatin-based hydrogel, its preparation method, and its application. This invention relates to the field of hydrogel technology and addresses the complex preparation process and suboptimal mechanical properties of gelatin-based hydrogels in the prior art. The method comprises the following steps: adding an acrylic monomer, an olefin imidazolium cation, an organic electrolyte lithium salt, and an initiator to an aqueous gelatin solution to obtain a mixed solution; and subjecting the mixed solution to a polymerization reaction under ultraviolet light to obtain a gelatin-based hydrogel. The raw materials used in the preparation method provided herein are environmentally and human-friendly biomass macromolecular materials, and the various components exhibit synergistic effects in improving the performance of the gelatin-based hydrogel. The preparation method is simple and can be applied to large-scale production.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogels, and more particularly to a gelatin-based hydrogel and a preparation method and application thereof. Background Art

[0002] Hydrogel materials are widely used in biomedical engineering, flexible sensing, and environmental remediation due to their unique physical and chemical properties. Gelatin is extracted from collagen and is a natural polymer with good biocompatibility, degradability, and water solubility. In addition, gelatin has the advantages of low cost, high content, and non-toxicity, so it is widely used in the biomedical field. However, traditional gelatin-based hydrogels have poor mechanical properties and are extremely easy to swell, which is not conducive to their operation as flexible sensors in various environments. At present, people are in urgent need of flexible hydrogel sensors that still have good multifunctional applications under various environmental conditions.

[0003] At present, there are many methods in the existing technology to improve the mechanical properties of gelatin-based hydrogels, such as: the introduction of a double network structure, gelatin and polymer compounds (polyacrylic acid, polyacrylamide, etc.) are physically cross-linked to form a double network hydrogel, but its mechanical properties are relatively poor; a multifunctional network structure, by combining gelatin with other functional polymers (chitosan, hyaluronic acid, sodium alginate, etc.) to form a multifunctional composite hydrogel, its multifunctional network can improve the mechanical properties and biofunctionality of the hydrogel, but the degree of improvement is still not ideal; filling nanocomposite materials, introducing nanomaterials (nanoclay, carbon nanotubes, graphene, silica nanoparticles, etc.) into gelatin-based hydrogels to form nanocomposite hydrogels, its physical cross-linking points increase the strength and toughness of the material, but the filling distribution of the nanomaterials is uneven, resulting in poor mechanical properties of the hydrogel.

[0004] Therefore, existing hydrogels often have complex preparation processes and the resulting hydrogels have poor mechanical properties. Summary of the Invention

[0005] The present invention provides a gelatin-based hydrogel and a preparation method and application thereof, which are used to solve the problems of complex preparation process and unsatisfactory mechanical properties of gelatin-based hydrogels in the prior art.

[0006] In a first aspect, the present invention provides a method for preparing a gelatin-based hydrogel, comprising the following steps: adding an acrylic monomer, an olefin imidazole cation, an organic electrolyte lithium salt and an initiator to a gelatin aqueous solution to obtain a mixed solution; and subjecting the mixed solution to a polymerization reaction under ultraviolet light to obtain the gelatin-based hydrogel.

[0007] As a possible implementation, the acrylic monomer is one or more of acrylic acid, methacrylic acid, and dimethacrylic acid; and / or the olefin imidazolium cation is one or more of 1-vinyl-3-hexyl imidazolium ion, 1-vinyl-3-octyl imidazolium ion, 1-propenyl-3-ethyl imidazolium ion, 1-propenyl-3-propyl imidazolium ion and 1-vinyl-3-butyl imidazolium ion; and / or the organic electrolyte lithium salt is one or more of lithium bis(trifluoromethanesulfonyl imide), lithium bis(fluorosulfonyl imide), lithium tetrafluoroborate, lithium hexafluorophosphate, and lithium bis(oxalato)borate; and / or the initiator is one or more of α-ketoglutaric acid, 2,2-azobis(2-methylpropylimidazole) dihydrochloride, and 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone.

[0008] As a possible implementation method, the mass percentage concentration of the gelatin aqueous solution is 1% to 30%; and / or the mass ratio of the gelatin aqueous solution, the acrylic monomer, the olefin imidazole cation, the organic electrolyte lithium salt and the initiator is 4:0.2 to 2:0.1 to 2:0.1 to 2:0.0003 to 0.01.

[0009] As a possible implementation method, the reaction conditions of the polymerization reaction are: temperature 10-50° C., and duration 2-12 h.

[0010] In a second aspect, the present invention provides a gelatin-based hydrogel prepared by any possible implementation method of the first aspect.

[0011] In a third aspect, the present invention provides a gelatin-based hydrogel prepared by the preparation method described in any possible implementation of the first aspect or the use of the gelatin-based hydrogel described in the second aspect in an aqueous environment.

[0012] As a possible implementation method, the gelatin-based hydrogel is applied to human motion monitoring.

[0013] As a possible implementation, the gelatin-based hydrogel is applied to wearable devices.

[0014] The present invention provides a method for preparing a gelatin-based hydrogel, wherein the raw materials used in its preparation exhibit synergistic effects in improving the performance of the gelatin-based hydrogel. Gelatin acts as a first-layer network to dissipate energy, while acrylic monomers copolymerize with olefinic imidazolium cations to form a chain backbone that supports the hydrogel, thereby imparting excellent flexibility to the hydrogel. The alkyl hydrophobic chains of the olefinic imidazolium cations aggregate within the hydrogel to form hydrophobic interactions, acting as a barrier between the hydrogel and the aqueous phase, inhibiting the diffusion of most substances. Furthermore, they partially aggregate in aqueous solution to form a phase-separated structure, providing multi-scale energy dissipation and ion channels, significantly enhancing the hydrogel's toughness and conductivity. Furthermore, the increased hydrophobicity promotes localized folding of the polymer chains, leading to chain extension during stretching and supporting the hydrogel's ultrahigh tensile state. Simultaneously, the anions of the introduced organic electrolyte lithium salt combine with the imidazolium cations to form stronger electrostatic attraction, allowing the lithium ions to form new strong lithium bonds with the carbonyl groups on the acrylic monomers. In addition, gelatin, acrylic monomers, olefin imidazolium cations and organic electrolyte lithium salts can form multiple hydrogen bonds to improve the mechanical properties of the hydrogel.

[0015] The gelatin-based hydrogel provided by the present invention is a multi-crosslinked hydrogel with multiple hydrogen bonds, ionic bonds, hydrophobic associations and strong lithium bonds. It does not contain chemical crosslinking, has a simple preparation method, and is friendly to the environment and the human body. The gelatin-based hydrogel provided by the present invention has good stretchability and anti-swelling properties, good frost resistance, electrical conductivity and antibacterial properties; its fracture strain can reach about 4000%, and its fracture energy can reach 2152kJ / m 3 , the swelling rate after 15 days was only 15.48%. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 This is a stress-strain test diagram of the gelatin-based hydrogel provided in an embodiment of the present invention.

[0018] Figure 2 A comparison of the 15-day swelling conditions of the gelatin-based hydrogels provided in the embodiments of the present invention, wherein, from left to right: the original size diagram, the swelling conditions of Product A, Product G, Product H, and Product I after 15 days.

[0019] Figure 3 This is a DSC graph of the gelatin-based hydrogel provided in an embodiment of the present invention.

[0020] Figure 4 Schematic diagram of the conductive performance test of the gelatin-based hydrogel provided in an embodiment of the present invention.

[0021] Figure 5 This is a time-current curve diagram of the gelatin-based hydrogel provided by an embodiment of the present invention when the finger is bent at different angles. DETAILED DESCRIPTION

[0022] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments 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 are within the scope of protection of the present invention.

[0023] In order to solve the problems of complex preparation process, unsatisfactory mechanical properties and unsatisfactory application effects of gelatin-based hydrogels in the prior art, an embodiment of the present invention provides a preparation experiment of a gelatin-based hydrogel. The gelatin-based hydrogel prepared by the present invention is a multi-crosslinked hydrogel with multiple hydrogen bonds, ionic bonds, hydrophobic associations and strong lithium bonds, and does not contain chemical crosslinks. The various components have a synergistic effect in improving the performance of the gelatin-based hydrogel.

[0024] Furthermore, the embodiments of the present invention provide a mechanical property test experiment of a gelatin-based hydrogel and a hydrogel in the prior art, which verifies that the gelatin-based hydrogel provided by the present invention has more excellent mechanical properties.

[0025] Furthermore, an embodiment of the present invention provides an application performance test experiment of a gelatin-based hydrogel, which verifies that the gelatin-based hydrogel provided by the present invention has more excellent application performance.

[0026] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0027] Example 1

[0028] This example provides an experiment for preparing a gelatin-based hydrogel.

[0029] A gelatin aqueous solution, acrylic acid, 1-vinyl-3-hexyl imidazole bromide, lithium bis(trifluoromethanesulfonyl)imide and α-ketoglutaric acid in a mass ratio of 4:1.1:1:1.1:0.005 were mixed to obtain a mixed solution A, wherein the mass percentage concentration of the gelatin aqueous solution was 10%; the mixed solution A was subjected to a polymerization reaction under ultraviolet light initiation conditions at a reaction temperature of 25° C. and a reaction time of 9 hours to obtain a product A.

[0030] A gelatin aqueous solution, methacrylic acid, 1-vinyl-3-octylimidazole chloride, lithium bis(fluorosulfonyl)imide and 2,2-azobis(2-methylpropylimidazole) dihydrochloride in a mass ratio of 4:1.5:1:1.1:0.0003 were mixed to obtain a mixed solution B, wherein the mass percentage concentration of the gelatin aqueous solution was 15%; the mixed solution B was subjected to a polymerization reaction under ultraviolet light initiation conditions at a reaction temperature of 20°C and a reaction time of 4 hours to obtain a product B.

[0031] A gelatin aqueous solution, dimethylacrylic acid, 1-propenyl-3-ethylimidazole bromide, lithium tetrafluoroborate and 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone in a mass ratio of 4:0.8:1:1.2:0.005 are mixed to obtain a mixed solution C, wherein the mass percentage concentration of the gelatin aqueous solution is 20%; the mixed solution C is polymerized under ultraviolet light initiation conditions at a reaction temperature of 30°C and a reaction time of 10 hours to obtain a product C.

[0032] A gelatin aqueous solution, acrylic acid, 1-propenyl-3-propyl imidazole bromide, lithium hexafluorophosphate and α-ketoglutaric acid in a mass ratio of 4:0.5:0.8:1:0.001 were mixed to obtain a mixed solution D, wherein the mass percentage concentration of the gelatin aqueous solution was 25%; the mixed solution D was subjected to a polymerization reaction under ultraviolet light initiation conditions at a reaction temperature of 15°C and a reaction time of 12 hours to obtain a product D.

[0033] A gelatin aqueous solution, methacrylic acid, 1-vinyl-3-butyl imidazole chloride, lithium bis(oxalato)borate and 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone in a mass ratio of 4:2:1.8:2:0.01 were mixed to obtain a mixed solution E, wherein the mass percentage concentration of the gelatin aqueous solution was 10%; the mixed solution E was subjected to a polymerization reaction under ultraviolet light initiation conditions, the reaction temperature was 25°C, and the reaction time was 8 hours to obtain product E.

[0034] A gelatin aqueous solution, 1-vinyl-3-hexyl imidazole bromide, lithium bis(trifluoromethanesulfonyl)imide, and α-ketoglutaric acid in a mass ratio of 4:1:1.1:0.005 were mixed to obtain a mixed solution F, wherein the mass percentage concentration of the gelatin aqueous solution was 10%; the mixed solution F was subjected to a polymerization reaction under ultraviolet light initiation conditions at a reaction temperature of 25° C. and a reaction time of 9 hours to obtain a product F.

[0035] A gelatin aqueous solution, acrylic acid, lithium bis(trifluoromethanesulfonyl)imide and α-ketoglutaric acid in a mass ratio of 4:1.1:1.1:0.005 were mixed to obtain a mixed solution G, wherein the mass percentage concentration of the gelatin aqueous solution was 10%; the mixed solution G was subjected to a polymerization reaction under ultraviolet light initiation conditions at a reaction temperature of 25°C and a reaction time of 9 hours to obtain a product G.

[0036] A gelatin aqueous solution, acrylic acid, 1-vinyl-3-hexyl imidazole bromide, and α-ketoglutaric acid were mixed in a mass ratio of 4:1.1:1:0.005 to obtain a mixed solution H, wherein the mass percentage concentration of the gelatin aqueous solution was 10%. The mixed solution H was polymerized under ultraviolet light initiation conditions at a reaction temperature of 25° C. and a reaction time of 9 hours to obtain a product H.

[0037] A gelatin aqueous solution, acrylic acid, and α-ketoglutaric acid in a mass ratio of 4:1.1:0.005 were mixed to obtain a mixed solution I, wherein the mass percentage concentration of the gelatin aqueous solution was 10%. The mixed solution I was polymerized under ultraviolet light initiation conditions at a reaction temperature of 25° C. and a reaction time of 9 hours to obtain a product I.

[0038] Example 2

[0039] This embodiment provides a mechanical property testing experiment of a gelatin-based hydrogel.

[0040] In this example, the products A to I, multifunctional composite hydrogel and nanocomposite hydrogel prepared in Example 1 were subjected to tensile strain, fracture energy and 15-day swelling rate test experiments, wherein product I is a double network hydrogel, and the obtained results are shown in Table 1 and Figures 1-2 The results shown.

[0041] Tensile strain experiments: A UTM-2102 universal testing machine (Jinan Kesheng Co., Ltd., China) was used to evaluate the tensile mechanical properties of the hydrogels at room temperature. The hydrogels were cut into dumbbell shapes (JIS-K6215-7) with a length of 12 mm, a width of 2 mm, and a thickness of 1 mm. Tensile tests were performed using a 50 N force transducer at a strain rate of 100 mm / min. The area under the stress-strain curve was used to calculate the fracture energy.

[0042] Swelling rate test experiment: The hydrogel was soaked in water for 15 days and its weight before and after was recorded. The swelling rate was determined by the formula (m-m0) / m0, where m0 is the initial weight of the hydrogel and m is the weight after swelling.

[0043] Table 1 Mechanical properties test results

[0044]

[0045]

[0046] As shown in Table 1, Products A to E all exhibit good tensile strain, fracture energy, and swelling ratio, and possess excellent mechanical properties. Product F, compared to Product A, fails to form a gel, indicating that the acrylic monomers polymerize to form a hydrogel chain backbone that supports the hydrogel morphology, and that the hydrogen bonds formed with gelatin play an important role in the hydrogel's mechanical properties. Product G, compared to Product A, exhibits an excessively high swelling ratio, which limits its application in aquatic environments (rainy days, swimming). This indicates that the alkyl hydrophobic chains of the olefin imidazolium cations can aggregate within the hydrogel to form hydrophobic interactions, acting as a barrier between the hydrogel and the aqueous phase and inhibiting the diffusion of most substances. Product H, compared to Product A, exhibits poor mechanical properties, indicating that the hydrogen and ionic bonds formed between the organic electrolyte lithium salt and other components play an important role in improving the mechanical properties of the product. Product I, compared to Product A, exhibits poor mechanical properties, indicating that the combined action of the olefin imidazolium cation and the organic electrolyte lithium salt can significantly enhance the mechanical properties of the hydrogel.

[0047] Example 3

[0048] This embodiment provides an application performance testing experiment of a gelatin-based hydrogel.

[0049] In this example, the products A to I prepared in Example 1 were used to perform DSC (differential scanning calorimetry) and conductivity test experiments. Among them, product I is a double network hydrogel for performance comparison, and the results are shown in Table 2 and Table 3. Figures 3-4 The results shown.

[0050] DSC test: The antifreeze properties of the gel were evaluated using a differential scanning calorimeter (DSC 250; TA Instruments, USA) by cooling from 20 °C to -60 °C at a rate of 5 °C / min.

[0051] Conductivity: The conductivity of the hydrogels was measured using an electrochemical workstation (CHI660E, Shanghai Chenhua Instrument Co., Ltd.). The R (Ω) of the hydrogel was calculated using the formula R = U / I, where U represents voltage and I represents current, which can be directly obtained from the source meter. The electrical conductivity (δ, S / m) was calculated using the formula δ = L / (R × S), where L is the length of the hydrogel, R is the resistance, and S is the cross-sectional area.

[0052] Table 2 Application performance test results

[0053] Temperature (℃) Conductivity (s / m) Product A -30.8 1.7 Product B -29.5 1.65 Product C -28.1 1.58 Product D -30.2 1.74 Product E -27.3 1.66 Product F - - Product G -20.4 1.0 Product H -13.6 0.68 Product I -11.5 0.32

[0054] As shown in Table 2, products A to E all exhibit good antifreeze and electrical conductivity. Product G exhibits lower antifreeze and electrical conductivity compared to product A, indicating that the olefinic imidazolium cation disrupts the hydrogen bond network of water molecules, lowering the freezing point of the hydrogel and thus enhancing its antifreeze properties. It also provides freely mobile cations within the hydrogel, improving electrical conductivity. Product H exhibits poorer antifreeze and electrical conductivity compared to product A, indicating that the organic electrolyte lithium salt lowers the freezing point of water, preventing the hydrogel from freezing at low temperatures and improving antifreeze properties. Furthermore, the lithium salt provides highly mobile lithium ions within the hydrogel, enhancing overall electrical conductivity. Product I exhibits lower antifreeze and electrical conductivity compared to product A, indicating that the combined action of the olefinic imidazolium cation and the organic electrolyte lithium salt significantly enhances the antifreeze and electrical conductivity of the hydrogel.

[0055] This example conducts a finger bending sensor signal experiment on product A and obtains Figure 5 The results shown by Figure 5 It can be seen that product A has good sensitivity.

[0056] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0057] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A method for preparing a gelatin-based hydrogel, characterized in that: The following steps are involved: adding acrylic monomer, olefin imidazole cation, organic electrolyte lithium salt and initiator into a gelatin aqueous solution to obtain a mixed solution; The mixed solution is subjected to polymerization reaction under ultraviolet light to obtain the gelatin-based hydrogel.

2. The preparation method according to claim 1, characterized in that The acrylic monomer is one or a combination of acrylic acid, methacrylic acid, and dimethacrylic acid; And / or, the olefin imidazolium cation is one or a combination of 1-vinyl-3-hexyl imidazolium ion, 1-vinyl-3-octyl imidazolium ion, 1-propenyl-3-ethyl imidazolium ion, 1-propenyl-3-propyl imidazolium ion and 1-vinyl-3-butyl imidazolium ion; And / or, the organic electrolyte lithium salt is one or a combination of bis(trifluoromethanesulfonyl)imide lithium, bis(fluorosulfonyl)imide lithium salt, lithium tetrafluoroborate, lithium hexafluorophosphate, and lithium bis(oxalato)borate; And / or, the initiator is one or a combination of α-ketoglutaric acid, 2,2-azobis(2-methylpropylimidazole) dihydrochloride, and 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone.

3. The preparation method according to claim 1, characterized in that The mass percentage concentration of the gelatin aqueous solution is 1% to 30%; And / or, the mass ratio of the gelatin aqueous solution, the acrylic monomer, the olefin imidazolium cation, the organic electrolyte lithium salt and the initiator is 4:0.2-2:0.1-2:0.1-2:0.0003-0.

01.

4. The preparation method according to claim 1, characterized in that The polymerization reaction conditions are: temperature 10-50° C., and duration 2-12 h.

5. A gelatin-based hydrogel prepared by the preparation method according to any one of claims 1 to 4.

6. Use of the gelatin-based hydrogel prepared by the preparation method according to any one of claims 1 to 4 or the gelatin-based hydrogel according to claim 5 in an aqueous environment.

7. The use according to claim 6, characterized in that The gelatin-based hydrogel is used for human motion monitoring.

8. The use according to claim 6, characterized in that The gelatin-based hydrogel is applied to wearable devices.

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