Hydrogel, preparation method and application thereof

Abstract

The preparation method of the hydrogel provided in the present application comprises the following steps: synthesizing an aqueous solution of a hydrogel precursor mixture, stirring and dissolving the aqueous solution of the hydrogel precursor mixture uniformly, and then condensing the mixture at low temperature to form a solid hydrogel with viscosity; irradiating the solid hydrogel with ultraviolet light to form a hydrogel with non-stick properties. The preparation method of the hydrogel provided in the present application adopts different chemical cross-linking methods to achieve the coexistence of sticky and non-sticky properties, thereby preparing a flexible and elastic hydrogel that can be sticky or non-sticky in specific areas, which can be used in the field of flexible chemical batteries and sensors.

Description

Technical Field

[0001] The present application relates to the technical field of gel materials, and in particular to a hydrogel, a preparation method and applications thereof. Background Art

[0002] With the rapid development of various flexible and wearable electronic products, electrochemical energy storage technology has become increasingly important in today's society. Maintaining electrochemical performance under various mechanical strains, especially bending and shear strains, is one of the fundamental properties of flexible energy storage devices. However, electrolytes play a vital role in the fabrication of flexible energy storage devices because they are directly related to the system's electrochemical stability potential window and the ion transport efficiency during electrochemical reactions. On the other hand, the inevitable evaporation of solvent water in flexible devices, accompanied by the precipitation of electrolytic salts, may cause irreversible performance degradation and lead to increased internal resistance. In fact, inappropriate separator materials can cause serious problems in energy storage devices, such as limited ionic conductivity due to insufficient electrolyte wettability and short circuits between electrodes due to poor mechanical strength. Therefore, the use of polymer hydrogels as electrolytes and separators in flexible energy storage devices is a growing trend.

[0003] Hydrogels are typically composed of elastically cross-linked hydrated polymer chains, the voids of which are filled with a high content of water, giving the gel its wet and soft properties. The charged functional groups on the polymer chains can effectively attract and position electrolytic ions within the network, while a large amount of solvent water can be absorbed and trapped within the framework. This results in their liquid ionic conductivity, while the dimensional stability of the solid can be retained, which is ideal for flexible energy storage devices. More importantly, the rich polymer chemistry and polymer engineering technologies have given hydrogel materials great designability and adjustability, making it possible to synthesize hydrogels with unique properties.

[0004] To impart specific functionalities to polymer hydrogels, such as rubber stretchability, self-healing, and mechanochromism, typical synthesis methods such as cross-linker-assisted synthesis and interpenetrating polymer network synthesis, as well as other related methods, can be employed to target specific functionalities. For example, it is widely believed that weak polymer hydrogels, originally made of randomly interlocked polymer chains filled with water, can be given a certain degree of rubber mechanical elasticity by cross-linking with specific cross-linkers.

[0005] A common characteristic of polymer host materials that can be converted into hydrogels is the presence of abundant hydrophilic functional groups, such as hydroxyl, carboxyl, sulfonic, acid, and amino groups. These functional groups are capable of forming abundant intermolecular and intramolecular hydrogen bonds, which are essential for hydrogel formation, resulting in weak physical crosslinking of the polymer. This unique property makes it possible to achieve exceptional water absorption. The abundance of functional groups also enables further polymer modification, such as grafting, copolymerization, and the preparation of interpenetrating polymer networks. Furthermore, since functional groups typically carry surface charges in aqueous environments, such as negatively charged carboxyl and positively charged sulfonic acid groups, this leads to favorable ionic interactions. Covalent bonds formed by various crosslinking agents are strong interactions, while ionic and hydrogen bonds can be classified as weak interactions. This combination of strong and weak interactions gives the material rubber-like properties such as stretchability, good toughness, and self-healing ability.

[0006] Although hydrogels synthesized by cross-linking have mechanical properties similar to those of non-cross-linked hydrogels, they exhibit relatively weak mechanical properties due to insufficient cross-linking. When the cross-linking is too high, the hydrogels become relatively rigid and brittle. However, by creating a double network cross-linking structure, it is possible to synthesize hydrogels that are both tough and soft, meaning they possess both elasticity and toughness.

[0007] Hydrogel materials are not only commonly used in energy storage devices but also as flexible sensing materials. For example, ionization sensing technology is a new generation of pressure sensing technology based on the electric double layer (EDL) capacitance mechanism. It uses materials rich in freely mobile ions. Under the influence of an electric field, the positive and negative ions in the material move toward the two electrodes, forming a compact ionic charge layer, known as the double layer, on the surfaces of the two electrodes. The double layer capacitance is primarily related to the contact area between the electrode and the ionic material. From an electrochemical perspective, this interface is essentially the same as that of a traditional electrochemical cell. Furthermore, although these two types of devices have completely different uses, they share very similar structures. Both consist of a pair of electrodes sandwiched between ionic materials, providing mobile charge carriers at the double layer interface. Mechanistically, both are based on the double layer at the electrode / ionic electrolyte interface. Batteries rely on the potential difference between the double layers at the interface to generate an output voltage, while ionization sensors directly measure the double layer capacitance to reflect applied pressure. In terms of materials, soft solid ionic materials (such as hydrogels, ion gels, and polymer electrolytes) can be used in both devices. The primary difference between solid-state chemical batteries and ion sensors lies in the properties of their materials. Solid-state batteries require smooth, tightly bonded solid ion materials to achieve higher power output and greater stability during bending. Ion pressure sensors, on the other hand, require a rough, stretchable interface between the electrode and the ion to achieve high sensitivity and repeatability. Typically, these materials require surface microstructure and non-stick properties to prevent adhesion between the electrode and the ion material under pressure.

[0008] The hydrogel materials currently developed and prepared only exist in one state: sticky or non-sticky. They cannot be controlled and fail to achieve the coexistence of sticky and non-sticky properties in the same hydrogel material. As a result, their applications are limited by their singleness and cannot meet the needs of flexible chemical batteries and flexible sensors at the same time. Summary of the Invention

[0009] In view of this, it is necessary to provide a hydrogel, preparation method and application thereof that can achieve coexistence of sticky and non-sticky properties in the same hydrogel material and can be prepared in a controllable manner to address the defects in the existing technology.

[0010] To solve the above problems, this application adopts the following technical solutions:

[0011] One of the purposes of this application is to provide a method for preparing a hydrogel, comprising the following steps:

[0012] Synthesizing a hydrogel precursor mixture aqueous solution, wherein the hydrogel precursor mixture aqueous solution includes gelatin, polyethylene glycol diacrylate, a viscous long-chain polymer, a glutaraldehyde aqueous solution, and a photoinitiator;

[0013] The hydrogel precursor mixture aqueous solution is stirred and dissolved uniformly, and then condensed at low temperature to form a viscous solid hydrogel;

[0014] The solid hydrogel is irradiated with ultraviolet light to form a hydrogel with non-sticky properties.

[0015] In some embodiments, in the step of synthesizing the hydrogel precursor mixture aqueous solution, the hydrogel precursor mixture aqueous solution includes the following components: 5-20 parts of gelatin, 5-20 parts of polyethylene glycol diacrylate, 1-5 parts of viscous long-chain polymer, 5-20 parts of 1% glutaraldehyde aqueous solution, 0.2-2 parts of photoinitiator and 100 parts of water.

[0016] In some embodiments, the viscous long-chain polymer includes at least one of polyethylene oxide, polyvinyl alcohol, and cellulose.

[0017] In some embodiments, the photoinitiator includes at least one of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide and 2-hydroxy-2-methyl-1-phenyl-1-propanone.

[0018] In some embodiments, after the aqueous solution of the hydrogel precursor mixture is stirred and dissolved uniformly, and then condensed at low temperature to form a viscous solid hydrogel, the stirring temperature is 35-50°C.

[0019] In some embodiments, after the hydrogel precursor mixture aqueous solution is stirred and dissolved uniformly, in the step of forming a viscous solid hydrogel by low-temperature condensation, the low-temperature condensation temperature is 1-20°C.

[0020] In some embodiments, after stirring and dissolving the aqueous solution of the hydrogel precursor mixture uniformly, the step of forming a viscous solid hydrogel by low-temperature condensation further includes the following step: stirring and dissolving the aqueous solution of the hydrogel precursor mixture uniformly, and then pouring the aqueous solution of the hydrogel precursor mixture into a mold for molding.

[0021] In some embodiments, the surface of the mold has a microstructure, so that the surface of the solid hydrogel after low-temperature condensation has different microstructures.

[0022] The second object of the present application is to provide a hydrogel prepared by any of the methods for preparing a hydrogel.

[0023] The third purpose of this application is to provide an application of the hydrogel in flexible chemical batteries and sensors.

[0024] This application adopts the above technical solution, and its beneficial effects are as follows:

[0025] The preparation method of the hydrogel provided in the present application comprises the following steps: synthesizing an aqueous solution of a hydrogel precursor mixture, stirring and dissolving the aqueous solution of the hydrogel precursor mixture uniformly, and then condensing the mixture at low temperature to form a solid hydrogel with viscosity; irradiating the solid hydrogel with ultraviolet light to form a hydrogel with non-stick properties. The preparation method of the hydrogel provided in the present application adopts different chemical cross-linking methods to achieve the coexistence of sticky and non-sticky properties, thereby preparing a flexible and elastic hydrogel that can be sticky or non-sticky in specific areas, which can be used in the field of flexible chemical batteries and sensors. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments of the present application or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0027] Figure 1 This is a flow chart of the steps of the method for preparing the hydrogel provided in Example 1 of the present application.

[0028] Figure 2 Actual photos of the hydrogel flexibility provided for application of this Example 1.

[0029] Figure 3Schematic diagram of the hydrogel compression strength provided in this embodiment 1.

[0030] Figure 4 This is a schematic diagram of the hydrogel adhesion provided in Example 1 of the present application. DETAILED DESCRIPTION

[0031] The following describes in detail embodiments of the present application, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0032] In the description of this application, it should be understood that the terms "upper", "lower", "horizontal", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on this application.

[0033] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. Throughout the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0034] In order to make the purpose, technical solutions and advantages of this application more clear, this application is further described in detail below with reference to the accompanying drawings and embodiments.

[0035] See also Figure 1 , a flow chart of a method for preparing a hydrogel provided in one embodiment of the present application includes the following steps S110 to S130, and the implementation method of each step is described in detail below.

[0036] Step S110: synthesizing a hydrogel precursor mixture aqueous solution, wherein the hydrogel precursor mixture aqueous solution includes gelatin, polyethylene glycol diacrylate, a viscous long-chain polymer, and a photoinitiator.

[0037] In this embodiment, gelatin can form a gel at low temperature through chemical cross-linking with glutaraldehyde; polyethylene glycol diacrylate can form a gel under ultraviolet light through a photoinitiator; and the viscous long-chain polymer can improve the overall flexibility and viscosity of the hydrogel through the form of an interpenetrating network.

[0038] In some embodiments, in the step of synthesizing the hydrogel precursor mixture aqueous solution, the hydrogel precursor mixture aqueous solution includes the following components: 5-20 parts of gelatin, 5-20 parts of polyethylene glycol diacrylate, 1-5 parts of viscous long-chain polymer, 5-20 parts of 1% glutaraldehyde aqueous solution, 0.2-2 parts of photoinitiator and 100 parts of water.

[0039] In some embodiments, the viscous long-chain polymer includes at least one of polyethylene oxide, polyvinyl alcohol, and cellulose.

[0040] In some embodiments, the photoinitiator includes at least one of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide and 2-hydroxy-2-methyl-1-phenyl-1-propanone.

[0041] In some embodiments, after the aqueous solution of the hydrogel precursor mixture is stirred and dissolved uniformly, and then condensed at low temperature to form a viscous solid hydrogel, the stirring temperature is 35-50°C.

[0042] In some embodiments, after the hydrogel precursor mixture aqueous solution is stirred and dissolved uniformly, in the step of forming a viscous solid hydrogel by low-temperature condensation, the low-temperature condensation temperature is 1-20°C.

[0043] Step S120: stirring and dissolving the hydrogel precursor mixture aqueous solution uniformly, and then condensing it at low temperature to form a viscous solid hydrogel.

[0044] Step S130: irradiating the solid hydrogel with ultraviolet light to form a non-sticky hydrogel.

[0045] In some embodiments, after stirring and dissolving the aqueous solution of the hydrogel precursor mixture uniformly, the step of forming a viscous solid hydrogel by low-temperature condensation further includes the following step: stirring and dissolving the aqueous solution of the hydrogel precursor mixture uniformly, and then pouring the aqueous solution of the hydrogel precursor mixture into a mold for molding.

[0046] In some embodiments, the surface of the mold has a microstructure, so that the surface of the solid hydrogel after low-temperature condensation has different microstructures.

[0047] It can be understood that the hydrogel preparation methods provided in the above embodiments of this application involve stirring and dissolving the aqueous solution of the hydrogel precursor mixture uniformly, then pouring it into a mold. This allows for low-temperature condensation to form a viscous solid hydrogel. UV light irradiation then eliminates the stickiness, resulting in a non-viscous hydrogel. Both states exhibit flexible and elastic properties, and the hydrogel surface can be given different microstructure designs by casting in different molds.

[0048] The preparation method of the hydrogel provided in this application adopts different chemical cross-linking methods to achieve the coexistence of sticky and non-sticky properties, and prepares flexible and elastic hydrogels that can be sticky or non-sticky in specific areas, which can be used in the field of flexible chemical batteries and sensors.

[0049] The above technical solutions of the present application are described in detail below with reference to specific embodiments.

[0050] Example 1:

[0051] The invention discloses a hydrogel precursor mixture aqueous solution, comprising the following components in parts by mass: 10 parts of gelatin, 15 parts of polyethylene glycol diacrylate, and 1.5 parts of polyethylene oxide, which are respectively added into 100 parts of distilled water and dissolved with stirring at 40° C., and then 1 part of 2-hydroxy-2-methyl-1-phenyl-1-propanone (1173) photoinitiator and 10 parts of 1% glutaraldehyde aqueous solution crosslinking agent are added to obtain a hydrogel precursor mixture aqueous solution.

[0052] Continue stirring for 2 minutes. Finally, pour the mixture into a mold and cool it at 10°C for about 1 hour to form a soft, elastic, and viscous hydrogel. Irradiate the viscous hydrogel with a UV lamp for 1 minute, and the stickiness disappears, turning the hydrogel into a non-viscous one.

[0053] See also Figure 2 , which is a real photo of the flexibility of the hydrogel provided in this embodiment.

[0054] See also Figure 3 , which is a schematic diagram of the compressive strength of the hydrogel provided in this embodiment.

[0055] The compression test of the hydrogel showed that the hydrogel has strong compression resistance. The maximum compression resistance of the viscous hydrogel is about 316kPa, and the maximum compression resistance of the non-viscous hydrogel is about 1112kPa.

[0056] See also Figure 4 , which is a schematic diagram of the hydrogel adhesion provided in this embodiment.

[0057] Adhesion peeling experiments on hydrogels showed that the adhesion force of sticky hydrogels was about 55 N / m; the adhesion force of non-sticky hydrogels was about 0 N / m, which can achieve a completely non-sticky state.

[0058] Example 2:

[0059] A hydrogel precursor mixture aqueous solution is synthesized, comprising the following components in parts by mass: 5 parts of gelatin, 20 parts of polyethylene glycol diacrylate, and 1 part of polyvinyl alcohol, which are respectively added into 100 parts of distilled water and dissolved with stirring at 35° C., followed by the addition of 2 parts of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide photoinitiator and 5 parts of a 1% glutaraldehyde aqueous solution crosslinking agent to obtain a hydrogel precursor mixture aqueous solution.

[0060] Continue stirring for 2 minutes. Finally, pour the mixture into a mold and cool it at 3°C ​​for about 1 hour to form a soft, elastic, and viscous hydrogel. Irradiate the viscous hydrogel with a UV lamp for 1 minute, and the stickiness disappears, turning the hydrogel into a non-viscous one.

[0061] Example 3:

[0062] The invention discloses a hydrogel precursor mixture aqueous solution, comprising the following components in parts by mass: 8 parts of gelatin, 5 parts of polyethylene glycol diacrylate, and 5 parts of cellulose, which are respectively added into 100 parts of distilled water and dissolved with stirring at 50° C., and then 0.2 parts of 2-hydroxy-2-methyl-1-phenyl-1-propanone (1173) photoinitiator and 20 parts of 1% glutaraldehyde aqueous solution crosslinking agent are added to obtain a hydrogel precursor mixture aqueous solution.

[0063] Continue stirring for 2 minutes. Finally, pour the mixture into a mold and cool it at 20°C for about an hour to form a soft, elastic, and viscous hydrogel. Irradiate the viscous hydrogel with a UV lamp for 1 minute, and the stickiness disappears, turning the hydrogel into a non-viscous one.

[0064] It can be understood that the various technical features of the above-described embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the various technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0065] The above are merely preferred embodiments of the present application and only specifically describe the technical principles of the present application. These descriptions are intended only to explain the principles of the present application and should not be construed in any way as limiting the scope of protection of the present application. Based on the explanations herein, any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present application, as well as other specific implementations of the present application that can be conceived by those skilled in the art without inventive effort, shall be included within the scope of protection of the present application.

Claims

1. A method for preparing a hydrogel, characterized in that: The steps include: A hydrogel precursor mixture aqueous solution is synthesized. The preparation method of the hydrogel precursor mixture aqueous solution comprises: adding 10 parts of gelatin, 15 parts of polyethylene glycol diacrylate, and 1.5 parts of polyethylene oxide to 100 parts of distilled water, stirring and dissolving them at 40° C., and then adding 1 part of 2-hydroxy-2-methyl-1-phenyl-1-propanone photoinitiator and 10 parts of 1% glutaraldehyde aqueous solution crosslinking agent to obtain a hydrogel precursor mixture aqueous solution; The hydrogel precursor mixture aqueous solution was stirred for 2 minutes, and finally poured into a mold and cooled at 10°C for 1 hour to form a soft and elastic viscous hydrogel. The viscous hydrogel was irradiated with UV light for 1 minute, and the viscosity disappeared and the hydrogel became non-viscous.

2. The method for preparing the hydrogel according to claim 1, wherein: The surface of the mold has a microstructure, so that the surface of the solid hydrogel after low-temperature condensation has different microstructures.

3. A hydrogel, characterized in that The hydrogel is prepared by the method for preparing the hydrogel according to any one of claims 1 to 2.

4. Use of the hydrogel according to claim 3 in flexible chemical batteries and sensors.

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