Macromolecular microsphere cross-linking agent, hydrogel and preparation method

Abstract

The invention relates to the technical field of hydrogel, and particularly discloses a macromolecular microsphere cross-linking agent, hydrogel and a preparation method. The macromolecular microsphere cross-linking agent is prepared from the following raw materials in parts by weight: 80 to 90 parts of ethyl acrylate, 30 to 50 parts of methacrylic acid, 1 to 5 parts of 1, 4-butanediol diacrylate, 0.1 to 2 parts of lauryl sodium sulfate, 1 to 5 parts of dipotassium phosphate and 2 to 8 parts of ammonium persulfate. The nano-composite hydrogel prepared through crosslinking of the macromolecular microsphere crosslinking agent has obvious advantages in the aspects of elongation at break, tensile stress and mechanical strength, and the mechanical property of the nano-composite hydrogel can be flexibly regulated and controlled according to the pH value of a system.

Description

Technical Field

[0001] The invention relates to the technical field of hydrogels, and in particular to a macromolecular microsphere crosslinking agent, a hydrogel and a preparation method. Background Art

[0002] Hydrogels have been widely used in many fields such as biomedical engineering, soft robotics, biosensors and bioelectronics due to their softness, biocompatibility and water content. These applications require hydrogels to have excellent mechanical properties, including high fracture toughness, appropriate modulus and superior stretchability. The low mechanical strength of traditional single-network hydrogels limits their stability and reliability in practical applications. Recently developed strategies to improve the mechanical properties of hydrogels include designing topological structures (e.g., sliding ring gels, uniform four-arm gels and highly entangled gels) to disperse stress within a single polymer network, introducing sacrificial bonds to dissipate energy (e.g., double network hydrogels and double cross-linked hydrogels), and introducing higher-order structures (e.g., microphase separation, microcrystals, fibers or fabrics). However, these strategies are limited to specific types of hydrogels and require the construction of heterogeneous structures or complex preparation processes.

[0003] Microgels are cross-linked polymer particles with sizes ranging from a few nanometers to a few micrometers. Their chemical and physical functions are easily programmable. Due to their unique microstructure and material properties, the mechanical properties of hydrogels can be enhanced. Microgel-based macromolecular microsphere crosslinkers are incorporated into hydrogels through physical or chemical crosslinking to ensure uniform distribution within the gel matrix to form nanocomposite hydrogels. The mechanical enhancement of physically cross-linked nanocomposite hydrogels depends on the size and stiffness of the macromolecular microspheres. Soft microspheres with small size and low modulus are more conducive to dispersing stress and crack propagation. The size of the macromolecular microspheres reported so far for preparing composite hydrogels by physical crosslinking is larger than 5μm, resulting in the inability to further optimize the mechanical properties of the nanocomposite hydrogels, and their mechanical properties cannot be adjusted according to the functionality of the macromolecular microsphere crosslinkers and lack flexible programming.

[0004] Therefore, it is necessary to provide a macromolecular microsphere crosslinking agent, a hydrogel and a preparation method to enhance the mechanical properties of the hydrogel and make its mechanical properties flexibly controllable. Summary of the invention

[0005] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention proposes a macromolecular microsphere crosslinking agent, a hydrogel and a preparation method to enhance the mechanical properties of the hydrogel and make its mechanical properties flexibly controllable.

[0006] The first aspect of the present invention provides a macromolecular microsphere cross-linking agent.

[0007] Specifically, in parts by weight, the raw materials of the macromolecular microsphere crosslinking agent include: 80-90 parts of ethyl acrylate, 30-50 parts of methacrylic acid, 1-5 parts of 1,4-butanediol diacrylate, 0.1-2 parts of sodium dodecyl sulfate, 1-5 parts of dipotassium hydrogen phosphate, and 2-8 parts of ammonium persulfate.

[0008] Preferably, the raw materials of the macromolecular microsphere crosslinking agent include, by weight: 80-85 parts of ethyl acrylate, 35-45 parts of methacrylic acid, 1-3 parts of 1,4-butanediol diacrylate, 0.5-1.5 parts of sodium dodecyl sulfate, 1-2 parts of dipotassium hydrogen phosphate, and 2-5 parts of ammonium persulfate.

[0009] Further preferably, the raw materials of the macromolecular microsphere crosslinking agent include, by weight: 82-85 parts of ethyl acrylate, 40-42 parts of methacrylic acid, 1-2 parts of 1,4-butanediol diacrylate, 0.5-1 part of sodium dodecyl sulfate, 1-2 parts of dipotassium hydrogen phosphate, and 2-5 parts of ammonium persulfate.

[0010] Preferably, the particle size of the macromolecular microsphere crosslinking agent is 50 to 100 nm.

[0011] More preferably, the particle size of the macromolecular microsphere crosslinking agent is 50 to 80 nm.

[0012] More preferably, the particle size of the macromolecular microsphere crosslinking agent is 70 to 80 nm.

[0013] The second aspect of the present invention provides a method for preparing a macromolecular microsphere cross-linking agent.

[0014] Specifically, the following steps are included:

[0015] (1) mixing ethyl acrylate, methacrylic acid and 1,4-butanediol diacrylate to prepare a comonomer solution;

[0016] (2) First, 10-20% of the comonomer solution is added to water containing sodium dodecyl sulfate, dipotassium hydrogen phosphate and ammonium persulfate, and the temperature is raised and stirred under a protective gas atmosphere to form seeds; then the remaining comonomer solution is added until the feeding is completed to obtain a macromolecular microsphere crosslinking agent.

[0017] Preferably, in step (2), the protective gas includes at least one of nitrogen and argon.

[0018] Preferably, in step (2), the heating temperature is 65-100°C.

[0019] Further preferably, in step (2), the heating temperature is 70-90°C.

[0020] More preferably, in step (2), the heating temperature is 80°C.

[0021] Preferably, in step (2), the stirring time is 10 to 60 minutes.

[0022] More preferably, in step (2), the stirring time is 20 to 40 minutes.

[0023] More preferably, in step (2), the stirring time is 30 min.

[0024] A third aspect of the present invention provides a hydrogel.

[0025] Specifically, the raw materials of the hydrogel include, by weight: 1-10 parts of macromolecular microsphere crosslinking agent, 35-45 parts of acrylamide, 0.03-0.10 parts of N,N,N',N'-tetramethylethylenediamine, and 0.03-0.15 parts of ammonium persulfate.

[0026] Preferably, the raw materials of the hydrogel include, by weight: 1 to 8 parts of a macromolecular microsphere crosslinking agent, 40 to 45 parts of acrylamide, 0.03 to 0.10 parts of N,N,N',N'-tetramethylethylenediamine, and 0.03 to 0.15 parts of ammonium persulfate.

[0027] Further preferably, the raw materials of the hydrogel include, by weight: 1 to 8 parts of a macromolecular microsphere crosslinking agent, 40 to 41 parts of acrylamide, 0.03 to 0.05 parts of N,N,N',N'-tetramethylethylenediamine, and 0.03 to 0.05 parts of ammonium persulfate.

[0028] Preferably, the raw material of the hydrogel further comprises 50 to 60 parts by weight of a solvent.

[0029] Further preferably, the raw material of the hydrogel further comprises 50 to 59 parts by weight of a solvent.

[0030] More preferably, the raw material of the hydrogel further comprises 51 to 59 parts of solvent by weight.

[0031] Preferably, the solvent comprises deionized water.

[0032] A fourth aspect of the present invention provides a method for preparing a hydrogel.

[0033] Specifically, the following steps are included:

[0034] The acrylamide and the macromolecular microsphere cross-linking agent are dissolved and dispersed in deionized water, and then N,N,N',N'-tetramethylethylenediamine and ammonium persulfate are added, the pH value is adjusted, and the mixture is polymerized at room temperature to prepare a hydrogel.

[0035] Preferably, the pH value is 5-8.

[0036] More preferably, the pH value is 5.5 to 7.5.

[0037] More preferably, the pH value is 5.7-7.4.

[0038] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0039] The nanocomposite hydrogel prepared by cross-linking a macromolecular microsphere cross-linking agent of the present invention has obvious advantages in elongation at break, tensile stress and mechanical strength, and its mechanical properties can be flexibly adjusted according to the pH value of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a graph showing the particle size and pH responsiveness test results of the macromolecular microsphere crosslinker of Example 1. DETAILED DESCRIPTION

[0041] In order to make the technical scheme of the present invention more clearly understood by those skilled in the art, the following embodiments are listed for illustration. It should be pointed out that the following embodiments do not limit the protection scope of the present invention.

[0042] Unless otherwise specified, the raw materials, reagents or devices used in the following examples can be obtained from conventional commercial sources or by existing known methods.

[0043] Example 1

[0044] A macromolecular microsphere cross-linking agent and a preparation method thereof.

[0045] The raw materials of the macromolecular microsphere crosslinking agent are calculated by weight as follows: 82 parts of ethyl acrylate, 41 parts of methacrylic acid, 1.7 parts of 1,4-butanediol diacrylate, 0.9 parts of sodium dodecyl sulfate, 1.55 parts of dipotassium hydrogen phosphate, 5.0 parts of ammonium persulfate, and 250 parts of deionized water. The pH value of the prepared macromolecular microsphere crosslinking agent is measured to be 6.2, and the particle size is 76nm.

[0046] The preparation method is as follows:

[0047] (1) mixing ethyl acrylate, methacrylic acid and 1,4-butanediol diacrylate to prepare a comonomer solution;

[0048] (2) First, 12.5% ​​of the comonomer solution is added to water containing sodium dodecyl sulfate, dipotassium hydrogen phosphate and ammonium persulfate, and the temperature is raised to 80° C. under an argon atmosphere, and mechanically stirred for 30 minutes to form seeds; then the remaining 87.5% of the comonomer solution is added until the feeding is completed, thereby obtaining a macromolecular microsphere crosslinking agent.

[0049] Example 2

[0050] A hydrogel and a preparation method thereof.

[0051] The raw materials of the hydrogel are calculated by weight as follows: 1 part of a macromolecular microsphere crosslinking agent, 40 parts of acrylamide, 0.04 parts of N,N,N',N'-tetramethylethylenediamine, 0.04 parts of ammonium persulfate, and 58.7 parts of deionized water.

[0052] The preparation method is as follows:

[0053] Acrylamide and macromolecular microsphere cross-linking agent were dissolved and dispersed in deionized water, and then N,N,N',N'-tetramethylethylenediamine and ammonium persulfate were added. The pH value was adjusted to 6.2 using 2M NaOH, and the mixture was polymerized at room temperature to prepare a hydrogel.

[0054] Example 3

[0055] A hydrogel and a preparation method thereof.

[0056] The difference from Example 2 is that 2 parts of macromolecular microsphere crosslinking agent and 57.7 parts of deionized water are used. The addition of other raw materials and the preparation method of hydrogel are the same as those in Example 2.

[0057] Example 4

[0058] A hydrogel and a preparation method thereof.

[0059] The difference from Example 2 is that 4 parts of macromolecular microsphere crosslinking agent and 55.7 parts of deionized water are used. The addition of other raw materials and the preparation method of hydrogel are the same as those in Example 2.

[0060] Example 5

[0061] A hydrogel and a preparation method thereof.

[0062] The difference from Example 2 is that 8 parts of macromolecular microsphere crosslinking agent and 51.7 parts of deionized water are used. The addition of other raw materials and the preparation method of hydrogel are the same as those in Example 2.

[0063] Example 6

[0064] A hydrogel and a preparation method thereof.

[0065] The difference from Example 2 is that in the method for preparing the hydrogel, 2M NaOH is used to adjust the pH value to 5.7.

[0066] Example 7

[0067] A hydrogel and a preparation method thereof.

[0068] The difference from Example 2 is that in the method for preparing the hydrogel, 2M NaOH is used to adjust the pH value to 6.0.

[0069] Example 8

[0070] A hydrogel and a preparation method thereof.

[0071] The difference from Example 2 is that in the preparation method of the hydrogel, 2M NaOH is used to adjust the pH value to 6.4.

[0072] Example 9

[0073] A hydrogel and a preparation method thereof.

[0074] The difference from Example 2 is that in the preparation method of the hydrogel, 2M NaOH is used to adjust the pH value to 7.4.

[0075] Comparative Example 1

[0076] A single network hydrogel and a preparation method thereof.

[0077] The raw materials of the single network hydrogel are calculated by weight as follows: 40 parts of acrylamide, 0.05 parts of N,N'-methylenebisacrylamide, 0.04 parts of N,N,N',N'-tetramethylethylenediamine, 0.04 parts of ammonium persulfate, and 59.8 parts of deionized water.

[0078] The preparation method is as follows:

[0079] Acrylamide was dissolved and dispersed in deionized water, and then N,N'-methylenebisacrylamide, N,N,N',N'-tetramethylethylenediamine and ammonium persulfate were added and polymerized at room temperature to obtain a single network hydrogel.

[0080] Performance testing:

[0081] The mechanical properties of all dumbbell-shaped hydrogel samples (length 50 mm, gauge length 20 mm, thickness 2 mm, width 4 mm) were tested using a universal testing machine (Instron, 68TM-30), which was equipped with a 100N sensor and a 250N pneumatic clamp. The tensile speed was 50 mm / min, and the test yielded a stress-strain curve. The tensile modulus was calculated from the slope of the linear fit between 0 and 10 strains in the stress-strain curve; the elongation at break was the strain value of the stress sudden drop (i.e., sample fracture) in the stress-strain curve; the maximum tensile stress was the maximum stress in the stress-strain curve; and the tensile strength was the area of ​​the stress-strain curve.

[0082] like Figure 1It can be seen that the small-sized (76 nm) macromolecular microsphere cross-linking agent prepared by the present invention has pH responsiveness, and its size increases with the increase of pH.

[0083] Table 1 Test results of tensile properties of hydrogels prepared in various embodiments and comparative examples

[0084]

[0085] As can be seen from Table 1, the nanocomposite hydrogel prepared by crosslinking the macromolecular microsphere crosslinker prepared by the present invention has obvious advantages in elongation at break, tensile stress and mechanical strength compared with the traditional hydrogel crosslinked by the commercial small molecule crosslinker in Comparative Example 1. In addition, the tensile properties of the nanocomposite hydrogel prepared by the present invention can be regulated by the pH value of the system, which has obvious adjustability and flexibility.

[0086] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution obtained by any modification, equivalent replacement, improvement, etc. made by a person skilled in the art based on the concept of the present invention through logical analysis, reasoning or limited experiments on the basis of the prior art shall be within the scope of protection determined by the claims.

Claims

1. A macromolecular microsphere crosslinking agent, characterized in that: The raw materials of the macromolecular microsphere crosslinking agent include, by weight: 80-90 parts of ethyl acrylate, 30-50 parts of methacrylic acid, 1-5 parts of 1,4-butanediol diacrylate, 0.1-2 parts of sodium dodecyl sulfate, 1-5 parts of dipotassium hydrogen phosphate, and 2-8 parts of ammonium persulfate.

2. The macromolecular microsphere crosslinking agent according to claim 1, characterized in that: The particle size of the macromolecular microsphere cross-linking agent is 50-100 nm.

3. The method for preparing the macromolecular microsphere crosslinking agent according to any one of claims 1 to 2, characterized in that: The following steps are involved: (1) mixing ethyl acrylate, methacrylic acid and 1,4-butanediol diacrylate to prepare a comonomer solution; (2) First, 10-20% of the comonomer solution is added to water containing sodium dodecyl sulfate, dipotassium hydrogen phosphate and ammonium persulfate, and the temperature is raised and stirred under a protective gas atmosphere to form seeds; then the remaining comonomer solution is added until the feeding is completed to obtain a macromolecular microsphere crosslinking agent.

4. The method for preparing the macromolecular microsphere crosslinking agent according to claim 3, characterized in that: In step (2), the protective gas includes at least one of nitrogen and argon.

5. The method for preparing the macromolecular microsphere crosslinking agent according to claim 3, characterized in that: In step (2), the heating temperature is 65-100°C.

6. The method for preparing the macromolecular microsphere crosslinking agent according to claim 3, characterized in that: In step (2), the stirring time is 10 to 60 minutes.

7. A hydrogel, characterized in that: The raw materials of the hydrogel include, by weight: 1-10 parts of a macromolecular microsphere crosslinking agent, 35-45 parts of acrylamide, 0.03-0.10 parts of N,N,N',N'-tetramethylethylenediamine, and 0.03-0.15 parts of ammonium persulfate.

8. The hydrogel according to claim 7, characterized in that The raw materials of the hydrogel also include 50 to 60 parts of solvent by weight.

9. The method for preparing the hydrogel according to any one of claims 7 to 8, characterized in that: The following steps are involved: The acrylamide and the macromolecular microsphere cross-linking agent are dissolved and dispersed in deionized water, and then N,N,N',N'-tetramethylethylenediamine and ammonium persulfate are added, the pH value is adjusted, and the mixture is polymerized at room temperature to prepare a hydrogel.

10. The method for preparing the hydrogel according to claim 9, characterized in that: The pH value is 5-8.

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