A ferulic acid-mediated highly adhesive hydrogel composition, the hydrogel, its preparation method and application

Abstract

This invention relates to the field of hydrogel materials technology, specifically to a ferulic acid-mediated highly adhesive hydrogel composition, the hydrogel itself, its preparation method, and its applications. The ferulic acid-mediated highly adhesive hydrogel provided by this invention not only possesses good mechanical properties but also excellent adhesion and sensing properties. Specifically, the ferulic acid-mediated highly adhesive hydrogel has a maximum tensile strength of 149.7 kPa, at which point the tensile strain is 460%. It exhibits good adhesion to various material surfaces, with adhesion strengths of 153.9 kPa, 233.4 kPa, and 313.2 kPa to pigskin, glass, and wood chips, respectively. As a strain sensor, the gel maintains a stable electrical signal after 150 tensile cycles under 50% strain conditions, indicating that its sensing performance is stable and repeatable. Therefore, the ferulic acid-mediated highly adhesive hydrogel provided by this invention has applications in the field of wearable electronic devices.

Description

Technical Field

[0001] This invention relates to the field of hydrogel materials technology, specifically to a ferulic acid-mediated highly adhesive hydrogel composition, the hydrogel, its preparation method, and its applications. Background Technology

[0002] Hydrogel materials are a class of materials composed of three-dimensional network polymers and liquids. Their unique structure endows them with excellent biodegradability, biocompatibility, flexibility, and mechanical properties similar to human tissue, making them highly promising for health monitoring, drug delivery, and biomedical engineering. In health monitoring, certain types of hydrogels can mimic the stretchability and elastic modulus of human skin, allowing them to adhere closely to complex surfaces such as skin and joint surfaces, thus effectively reducing the discomfort associated with traditional rigid sensors.

[0003] However, poor adhesion of hydrogels is one of the main bottlenecks in their practical applications, especially in fields such as flexible electronics, wound dressings, and tissue engineering. For example, when hydrogels are used as flexible electronics or bioelectrodes, poor adhesion can lead to problems such as increased interfacial contact resistance, increased signal noise, and unstable signal transmission. Furthermore, hydrogels with poor adhesion are prone to detaching from the target area during dynamic movement, posing a risk of functional failure.

[0004] Existing solutions primarily involve adding natural or synthetic adhesives to impart adhesive properties to hydrogels. Despite significant progress, the brittle nature of hydrogels and the risk of uncontrolled mechanical damage in practical applications pose a serious challenge to maintaining good stability in these adhesive hydrogels. Summary of the Invention

[0005] To overcome the above problems, the present invention provides a ferulic acid-mediated highly adhesive hydrogel composition, the hydrogel, its preparation method and application.

[0006] To achieve the above technical objectives, the present invention adopts the following technical solution:

[0007] A first aspect of the present invention provides a ferulic acid-mediated highly adhesive hydrogel composition comprising:

[0008] ferulic acid;

[0009] Ferrous salts;

[0010] acrylic acid;

[0011] Hydrogen peroxide;

[0012] water;

[0013] The volume ratio of acrylic acid, hydrogen peroxide and water is (2.6~2.8):(0.08~0.1):(7.0~7.4).

[0014] Fe in ferric salts 3+ As an oxidizing agent, it can undergo a redox reaction with ferulic acid; in this process, ferulic acid is oxidized, while Fe... 3+ Reduced to Fe 2+ Meanwhile, the Fe produced by the above reaction 2+ It can act as a catalyst to promote the decomposition of hydrogen peroxide under acidic conditions to generate hydroxyl radicals; the generated hydroxyl radicals have extremely strong oxidizing properties, which can promote the polymerization of acrylic acid monomers to form polyacrylic acid, and can also promote the self-polymerization of ferulic acid to form polyferulic acid or copolymerize with acrylic acid monomers to form ferulic acid-acrylic acid copolymer.

[0015] In one or more embodiments, the volume ratio of acrylic acid, hydrogen peroxide, and water is 2.7:0.09:7.21.

[0016] In one or more embodiments, the mass ratio of ferulic acid to the total volume of acrylic acid, hydrogen peroxide, and water is (0.1~0.6) g / L.

[0017] In one or more embodiments, the trivalent iron salt includes either ferric chloride or ferric sulfate, preferably FeCl3·6H2O.

[0018] More preferably, the mass ratio of FeCl3·6H2O to the total volume of acrylic acid, hydrogen peroxide and water is (6.0~8.0) g / L.

[0019] In a second aspect of the present invention, a ferulic acid-mediated highly adhesive hydrogel is polymerized by mixing the ferulic acid-mediated highly adhesive hydrogel composition described in the first aspect; the polymerization temperature is 35~50°C.

[0020] In one or more embodiments, the polymerization temperature is 40°C.

[0021] In one or more embodiments, the ferulic acid-mediated highly adhesive hydrogel has a tensile strength of 90-150 kPa and a tensile strain of 460-570%.

[0022] In one or more embodiments, the ferulic acid-mediated highly adhesive hydrogel has an adhesion strength of 50~160 kPa to pigskin.

[0023] In one or more embodiments, the ferulic acid-mediated highly adhesive hydrogel has an adhesion strength of 60~240 kPa to glass.

[0024] In one or more embodiments, the ferulic acid-mediated highly adhesive hydrogel has an adhesion strength of 130~320 kPa to wood chips.

[0025] A third aspect of the present invention provides a method for preparing the ferulic acid-mediated highly adhesive hydrogel described in the second aspect, comprising the following steps:

[0026] Ferulic acid, ferric salt, acrylic acid and hydrogen peroxide aqueous solution are dispersed in water and polymerized to form a ferulic acid-mediated highly adhesive hydrogel.

[0027] In one or more embodiments, the polymerization temperature is 35~50°C, preferably 40°C.

[0028] A fourth aspect of the present invention provides the application of the ferulic acid-mediated highly adhesive hydrogel described in the second aspect or the ferulic acid-mediated highly adhesive hydrogel prepared by the preparation method described in the third aspect in the field of wearable electronic devices.

[0029] The beneficial effects of this invention are as follows:

[0030] (1) The ferulic acid-mediated highly adhesive hydrogel provided by this invention not only possesses good mechanical properties, but also excellent adhesion and sensing properties. Specifically, the ferulic acid-mediated highly adhesive hydrogel has a maximum tensile strength of 149.7 kPa, at which point the tensile strain is 460%. It exhibits good adhesion to various material surfaces, with adhesion strengths of 153.9 kPa, 233.4 kPa, and 313.2 kPa to pigskin, glass, and wood chips, respectively. Furthermore, it maintains a stable electrical signal after 150 stretch-release cycles under 50% strain conditions, indicating that its sensing performance is stable and repeatable. Therefore, the ferulic acid-mediated highly adhesive hydrogel provided by this invention has applications in the field of wearable electronic devices.

[0031] (2) The ferulic acid-mediated highly adhesive hydrogel provided by the present invention has a low gelation temperature, short gelation time, simple preparation method, low raw material cost, and has the potential for large-scale production. Attached Figure Description

[0032] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0033] Figure 1 For ferulic acid and Fe 3+ A schematic diagram of a redox reaction;

[0034] Figure 2X-ray photoelectron spectroscopy (XPS) spectra of ferulic acid, the ferulic acid-mediated highly adhesive hydrogel prepared in Example 1, and the polyacrylic acid hydrogel prepared in Comparative Example 1; wherein, (a) is the C 1s spectrum of ferulic acid, (b) is the C 1s spectrum of the ferulic acid-mediated highly adhesive hydrogel prepared in Example 1, (c) is the C 1s spectrum of the polyacrylic acid hydrogel prepared in Comparative Example 1, and (d) is the Fe 2p spectrum of the ferulic acid-mediated highly adhesive hydrogel prepared in Example 1.

[0035] Figure 3 The mechanical properties of the ferulic acid-mediated highly adhesive hydrogels obtained in Examples 1-6 and the polypropylene hydrogel prepared in Comparative Example 1 are shown.

[0036] Figure 4 The results show the adhesion properties of the ferulic acid-mediated highly adhesive hydrogels obtained in Examples 1-6 and the polypropylene hydrogel prepared in Comparative Example 1 without the addition of ferulic acid.

[0037] Figure 5 This is a graph showing the signal results of recording a human body during movement using a Source Measure Unit (SMU) testing device.

[0038] Figure 6 This is a diagram showing the self-healing result of the ferulic acid-mediated highly adhesive hydrogel prepared in Example 1 after 60 minutes of close contact with the cut cross-section. Detailed Implementation

[0039] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0040] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0041] Poor adhesion of hydrogels is one of the main bottlenecks in their practical applications, especially in fields such as flexible electronics, wound dressings, and tissue engineering. For example, when hydrogels are used as flexible electronics or bioelectrodes, poor adhesion can lead to increased interfacial contact resistance, increased signal noise, and unstable signal transmission. Furthermore, hydrogels with poor adhesion are prone to detaching from their target area during dynamic movement, posing a risk of functional failure.

[0042] Existing solutions primarily involve adding natural or synthetic adhesives to impart adhesive properties to hydrogels. Despite significant progress, the brittle nature of hydrogels and the risk of uncontrolled mechanical damage in practical applications pose a serious challenge to maintaining good stability in these adhesive hydrogels.

[0043] To overcome the above problems, this invention provides a ferulic acid-mediated highly adhesive hydrogel. The ferulic acid-mediated highly adhesive hydrogel provided by this invention not only possesses good mechanical properties, but also excellent adhesion and sensing properties.

[0044] Regarding improved adhesion: Ferulic acid contains phenolic hydroxyl, methoxy, and carboxyl groups, which can enhance the adhesion of the hydrogel by interacting with the matrix through electrostatic interactions or forming a dense hydrogen bond network. The Fe in ferric salts... 3+ As an oxidizing agent, it can undergo redox reactions with ferulic acid. The phenolic hydroxyl and methoxy groups in ferulic acid can be oxidized to o-benzoquinone, which can undergo Michael addition or Schiff base reactions with amino (-NH2) and mercapto (-SH) groups on the material surface, further improving the adhesion strength and durability of the hydrogel. Furthermore, the catechol structure of ferulic acid is similar to that of Fe... 3+ Strong coordination occurs, forming a dynamically reversible metal-phenol coordination bond, in which the coordinated Fe... 3+ It can also coordinate with the substrate to which it is adhered, further enhancing the adhesion.

[0045] Regarding the improvement of mechanical properties: the mechanical properties of ferulic acid-mediated highly adhesive hydrogels mainly depend on the polyacrylic acid network, in addition, Fe... 3+ It interacts strongly with ferulic acid or polyacrylic acid to form dynamic and reversible metal-phenol coordination bonds. These dynamic bonds can dissociate and recombine within the hydrogel, dissipating energy and greatly improving the hydrogel's toughness, tensile strength, and self-healing ability.

[0046] The ferulic acid-mediated highly adhesive hydrogel provided by this invention has good sensing performance. After 150 stretching cycles under 50% strain conditions, it still maintains a stable electrical signal, indicating that its sensing performance is stable and repeatable, and proving its reliability as a sensor for monitoring motion.

[0047] The ferulic acid-mediated highly adhesive hydrogel provided by this invention exhibits excellent self-healing properties. This is due to the presence of numerous hydrogen bonds in the gel network, along with Fe... 3+ It interacts strongly with the catechol structure of polyacrylic acid chain or ferulic acid to form dynamic and reversible metal-phenol coordination bonds, ensuring the self-healing ability of the gel sample.

[0048] The ferulic acid-mediated highly adhesive hydrogel provided by this invention has a low gelation temperature, short gelation time, simple preparation method, low raw material cost, and has the potential for large-scale production.

[0049] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0050] Example 1

[0051] 3 mg ferulic acid, 60 mg FeCl3·6H2O, 2.7 mL acrylic acid and 90 μL hydrogen peroxide aqueous solution were dispersed in 7.21 mL deionized water. After being fully dissolved and mixed, the mixture was placed in an oven at 40℃ and polymerized for 5 min to obtain a ferulic acid-mediated highly adhesive hydrogel.

[0052] Example 2

[0053] 4 mg ferulic acid, 70 mg FeCl3·6H2O, 2.7 mL acrylic acid and 90 μL hydrogen peroxide aqueous solution were dispersed in 7.21 mL deionized water. After being fully dissolved and mixed, the mixture was placed in an oven at 40℃ and polymerized for 5 min to obtain a ferulic acid-mediated highly adhesive hydrogel.

[0054] Example 3

[0055] 6 mg ferulic acid, 60 mg FeCl3·6H2O, 2.7 mL acrylic acid and 90 μL hydrogen peroxide aqueous solution were dispersed in 7.21 mL deionized water. After being fully dissolved and mixed, the mixture was placed in an oven at 40℃ and polymerized for 5 min to obtain a ferulic acid-mediated highly adhesive hydrogel.

[0056] Example 4

[0057] 4 mg ferulic acid, 80 mg FeCl3·6H2O, 2.7 mL acrylic acid and 90 μL hydrogen peroxide aqueous solution were dispersed in 7.21 mL deionized water. After being fully dissolved and mixed, the mixture was placed in an oven at 40℃ and polymerized for 5 min to obtain a ferulic acid-mediated highly adhesive hydrogel.

[0058] Example 5

[0059] 1 mg ferulic acid, 60 mg FeCl3·6H2O, 2.7 mL acrylic acid and 90 μL hydrogen peroxide aqueous solution were dispersed in 7.21 mL deionized water. After being fully dissolved and mixed, the mixture was placed in an oven at 40℃ and polymerized for 5 min to obtain a ferulic acid-mediated highly adhesive hydrogel.

[0060] Example 6

[0061] 2 mg ferulic acid, 60 mg FeCl3·6H2O, 2.7 mL acrylic acid and 90 μL hydrogen peroxide aqueous solution were dispersed in 7.21 mL deionized water. After being fully dissolved and mixed, the mixture was placed in an oven at 40℃ and polymerized for 5 min to obtain a ferulic acid-mediated highly adhesive hydrogel.

[0062] Figure 1 For ferulic acid and Fe 3+ A schematic diagram of a redox reaction. From Figure 1 It can be seen from this that Fe in ferric salts 3+ As an oxidizing agent, it can undergo a redox reaction with ferulic acid; in this process, ferulic acid is oxidized, while Fe... 3+ Reduced to Fe 2+ Meanwhile, the Fe produced by the above reaction 2+ It can act as a catalyst to promote the decomposition of hydrogen peroxide under acidic conditions, generating hydroxyl radicals. These hydroxyl radicals possess extremely strong oxidizing properties, promoting the polymerization of ferulic acid / acrylic acid monomers to form polymers. This polymerization process avoids the toxic initiators and crosslinking agents relied upon in the traditional preparation of polyacrylic acid gels. Furthermore, from... Figure 1 It can also be seen that during the oxidation of ferulic acid, phenolic radicals can be formed, which are eventually oxidized to o-benzoquinone.

[0063] Comparative Example 1

[0064] Polyacrylic acid hydrogels were obtained using conventional methods without the addition of ferulic acid.

[0065] The specific steps are as follows: 2 mg ammonium persulfate (APS), 6 mg N,N'-methylenebisacrylamide (MBA) and 2.7 mL acrylic acid are dispersed in 7.3 mL deionized water. After being fully dissolved and mixed evenly, the mixture is placed in an oven at 40℃ and polymerized for 2 h to obtain polyacrylic acid hydrogel.

[0066] Figure 2 X-ray photoelectron spectroscopy (XPS) spectra of ferulic acid, the ferulic acid-mediated highly adhesive hydrogel prepared in Example 1, and the polyacrylic acid hydrogel prepared in Comparative Example 1, from... Figure 2 As can be seen from the data, the ferulic acid-mediated highly adhesive hydrogel prepared in Example 1 exhibits obvious characteristic peaks of the ferulic acid molecule's benzene ring (π-π* vibrational peaks), thus proving the presence of ferulic acid in the ferulic acid-mediated highly adhesive hydrogel. Furthermore, the Fe 2p spectrum of the ferulic acid-mediated highly adhesive hydrogel shows the presence of Fe in the material. 2+ and Fe 3+ This indicates that it is composed of ferulic acid and Fe 3+ The redox reaction has already occurred.

[0067] Figure 3 The mechanical properties of the ferulic acid-mediated highly adhesive hydrogels obtained in Examples 1-6 and the polypropylene hydrogels prepared in the comparative examples are shown below. Figure 3 As can be seen from the data, the maximum tensile strength of the ferulic acid-mediated highly adhesive hydrogel in Example 4 is 149.7 kPa, at which point the tensile strain is 460%. In Comparative Example 1, without the addition of ferulic acid, the covalent cross-linked network of the polyacrylic acid hydrogel is sparse, the hydrogel structure is fragile, the tensile strength is low, and it is easy to break.

[0068] Figure 4 The results show the adhesion properties of the ferulic acid-mediated highly adhesive hydrogels obtained in Examples 1-6 and the polypropylene hydrogel prepared in Comparative Example 1. Figure 4 It can be seen that the ferulic acid-mediated highly adhesive hydrogel prepared in this invention exhibits significantly higher adhesion properties than the polypropylene hydrogel in Comparative Example 1. Specifically, the adhesion strengths of the hydrogel in Example 1 to pigskin, glass, and wood chips are 153.9 kPa, 233.4 kPa, and 224.7 kPa, respectively. This is because ferulic acid contains phenolic hydroxyl, methoxy, and carboxyl groups, which can enhance the adhesion of the hydrogel by electrostatic interaction or forming a dense hydrogen bond network with the matrix. In addition, the Fe in the ferric salt... 3+ As an oxidizing agent, it can undergo redox reactions with ferulic acid. The phenolic hydroxyl and methoxy groups in ferulic acid can be oxidized to o-benzoquinone, which can undergo Michael addition or Schiff base reactions with amino (-NH2) and mercapto (-SH) groups on the material surface, further improving the adhesion strength and durability of the hydrogel. Furthermore, the catechol structure of ferulic acid is similar to that of Fe... 3+ Strong coordination occurs, forming a dynamically reversible metal-phenol coordination bond, in which the coordinated Fe... 3+ It can also coordinate with the substrate to which it is adhered, further enhancing the adhesion.

[0069] Figure 5 To record signal results of human movement using a source surface microscopy (SMU) testing device, a ferulic acid-mediated highly adhesive hydrogel sample (30 mm long × 10 mm wide × 3 mm thick) prepared in Example 1 was directly applied to the skin and then connected to a source surface microscopy (SMU) to monitor the resistance changes of the sample during human movement. Human movement can be effectively distinguished by analyzing the frequency and amplitude of resistance changes in the strain sensor. The excellent stability and repeatability of the hydrogel can be demonstrated by measuring whether the strain sensor reproduces the changes in electrical signal. Results are as follows... Figure 5 As shown, the ferulic acid-mediated highly adhesive hydrogel, as a flexible strain sensor, still maintains a stable electrical signal after 150 stretching cycles under 50% strain conditions, indicating that its sensing performance is stable and repeatable, and proving its reliability as a sensor for monitoring motion.

[0070] Figure 6 The results show that, without external force, the ferulic acid-mediated highly adhesive hydrogel prepared in Example 1 self-heals after 60 minutes of close contact with the cut cross-section. This is due to the catechol structure of ferulic acid and the Fe... 3+ Strong coordination occurs, forming dynamic and reversible metal-phenol coordination bonds, which can enhance self-healing properties.

[0071] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A ferulic acid-mediated highly adhesive hydrogel composition, characterized in that, include: ferulic acid; Ferrous salts; acrylic acid; Hydrogen peroxide aqueous solution; Deionized water; The volume ratio of acrylic acid, hydrogen peroxide aqueous solution, and deionized water is (2.6~2.8):(0.08~0.1):(7.0~7.4). The mass ratio of ferulic acid to the total volume of acrylic acid, hydrogen peroxide aqueous solution, and deionized water is (0.1~0.6) g / L; The trivalent iron salt is FeCl3·6H2O, and the mass ratio of FeCl3·6H2O to the total volume of acrylic acid, hydrogen peroxide aqueous solution and deionized water is (6.0~8.0) g / L.

2. A ferulic acid-mediated highly adhesive hydrogel, characterized in that, It is formed by mixing and polymerizing the ferulic acid-mediated highly adhesive hydrogel composition according to claim 1; The polymerization temperature is 35~50℃.

3. The ferulic acid-mediated highly adhesive hydrogel as described in claim 2, characterized in that, The ferulic acid-mediated highly adhesive hydrogel exhibits an adhesion strength of 50–160 kPa to pigskin.

4. The ferulic acid-mediated highly adhesive hydrogel as described in claim 2, characterized in that, The ferulic acid-mediated highly adhesive hydrogel has an adhesion strength of 60~240 kPa to glass. The ferulic acid-mediated highly adhesive hydrogel exhibits an adhesion strength of 130~320 kPa to wood chips.

5. The method for preparing the ferulic acid-mediated highly adhesive hydrogel according to any one of claims 2 to 4, characterized in that, Includes the following steps: Ferulic acid, ferric salt, acrylic acid and hydrogen peroxide aqueous solution were dispersed in deionized water and polymerized to form a ferulic acid-mediated highly adhesive hydrogel.

6. The preparation method according to claim 5, characterized in that, The polymerization temperature is 35~50℃.

7. The application of the ferulic acid-mediated highly adhesive hydrogel according to any one of claims 2 to 4, or the ferulic acid-mediated highly adhesive hydrogel prepared by the preparation method according to claim 5 or 6, in the field of wearable electronic devices.

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