A hydrophobic hydrogen bond enhanced hydrogel and preparation method thereof

Abstract

This invention relates to the field of polymer chemistry, specifically to a hydrophobic hydrogen bond-reinforced hydrogel and its preparation method. It is composed of 30-60 parts of hydrophilic monomers, 10-30 parts of hydrophobic monomers, 1-5 parts of crosslinking agent, 0.1-1 parts of initiator, and 50-100 parts of water. The preparation process involves first dissolving and stirring to obtain a mixture, then heating to react and obtain a precursor, followed by water soaking and drying to obtain the final product. Its advantages are significant: excellent mechanical properties, tensile strength of 1.2-2.2 MPa, and elongation at break of 750%-1250%, due to the unique monomer interaction and crosslinking network; good temperature and humidity resistance, maintaining good structure and low loss rate after 10 days at 50℃ and 80% humidity; and a flexible preparation process with adjustable parameters, facilitating industrial production and showing promising applications and development potential in multiple fields.

Description

Technical Field

[0001] This invention relates to the field of polymer chemistry, specifically to a hydrophobic hydrogen bond-reinforced hydrogel and its preparation method. Background Technology

[0002] Hydrogels, as materials with unique properties, have shown potential application value in many fields. However, existing hydrogel materials have many limitations in terms of performance and preparation process, making it difficult to meet the growing and diversified needs.

[0003] In terms of mechanical properties, traditional hydrogels generally have low tensile strength, typically failing to reach 1 MPa, and their elongation at break is often limited to around 300%. This is because their network structure is not robust enough, lacking effective interactions to enhance the material's mechanical properties. For example, commonly used hydrophilic monomers such as polyvinyl alcohol, while possessing some hydrophilicity, cannot form abundant hydrogen bonds like the specific hydrophilic monomers in this invention (polyol monomers containing carboxyl and hydroxyl groups, with a specific range for the molar ratio of carboxyl to hydroxyl groups and the degree of polymerization). This results in insufficient strength and elasticity of the hydrogel. Simultaneously, the hydrophobic components in traditional hydrogels are often inappropriately selected, failing to form effective interactions between hydrophobic microdomains and hydrophilic parts. This results in a loose overall network structure, unable to withstand significant external tensile forces. When used as biomedical tissue engineering scaffolds, they cannot reliably support cell growth and tissue repair, easily leading to breakage and damage, severely limiting their application in fields with high mechanical performance requirements.

[0004] Existing hydrogels exhibit poor performance in terms of temperature and humidity resistance. When exposed to high temperature and humidity environments, such as 50°C and 80% humidity, the structural stability of traditional hydrogels is severely challenged. This is because their internal chemical bonds and intermolecular forces are weak, making them unable to effectively resist moisture erosion and thermal damage. Furthermore, the combination of hydrophilic and hydrophobic components is unbalanced, failing to form the synergistic hydrophilic and hydrophobic monomers and stable cross-linked network structure described in this invention. This results in structural loosening and significant mass loss after a short period of exposure to high temperature and humidity, failing to meet the requirements for use in outdoor products in tropical regions and industrial sensors operating in high temperature and humidity environments, thus greatly limiting their application scope.

[0005] From a manufacturing process perspective, traditional hydrogel preparation methods are relatively fixed and singular. The range of raw material choices is limited, and key parameters such as the ratio of hydrophilic to hydrophobic monomers, and the amounts of crosslinking agents and initiators, are difficult to adjust flexibly according to actual needs. Reaction conditions, such as temperature, time, and drying conditions, also lack diverse options. This results in hydrogels with relatively limited properties, failing to meet the specific performance requirements of different applications. Furthermore, traditional preparation processes may require harsh conditions such as high temperatures, which not only increases energy consumption but may also adversely affect the structure and properties of monomers, leading to unstable product quality. This also hinders large-scale industrial production, resulting in high production costs and limiting the widespread application and further development of hydrogel materials.

[0006] Chinese invention patent CN110938168A discloses a hydrophobic hydrogen bond-reinforced hydrogel and its preparation method, but it has drawbacks in terms of elongation at break, tensile strength, and structural integrity in high temperature and high humidity environments, which are difficult to meet the requirements.

[0007] In summary, existing hydrogel technologies have significant shortcomings in terms of mechanical properties, temperature and humidity resistance, and preparation processes. There is an urgent need for a new hydrogel material and its preparation method to overcome these problems, in order to expand the application fields of hydrogels and improve their performance and practicality. This invention is proposed based on this background. Summary of the Invention

[0008] The purpose of this invention is to provide a hydrophobic hydrogen bond-enhanced hydrogel and its preparation method, so as to solve the problems mentioned in the background art.

[0009] To solve the above-mentioned technical problems, the technical solution provided by the present invention is: a hydrophobic hydrogen bond-reinforced hydrogel, prepared from the following raw materials in parts by weight:

[0010] 30-60 parts of hydrophilic monomer, wherein the hydrophilic monomer is a polyol monomer containing carboxyl and hydroxyl groups, the molar ratio of carboxyl to hydroxyl groups is 1:2-1:3, and the degree of polymerization of the hydrophilic monomer is 100-500. This hydrophilic monomer with a specific structure can form abundant hydrogen bonds in the hydrogel network, thereby enhancing the hydrophilicity and mechanical properties of the hydrogel.

[0011] 10-30 parts of hydrophobic monomer, wherein the hydrophobic monomer is a long-chain alkyl acrylate monomer with an alkyl chain length of 8-16 carbon atoms. The hydrophobic monomer can form hydrophobic microdomains in the hydrogel system and interact with hydrophilic monomers, thereby further enhancing the network structure and stability of the hydrogel through hydrophobic association.

[0012] 1-5 parts of crosslinking agent, wherein the crosslinking agent is a aziridine compound with multiple functional groups and a functionality of 3-6, which can efficiently crosslink with hydrophilic and hydrophobic monomers during the hydrogel formation process to form a three-dimensional network structure and improve the strength and elasticity of the hydrogel.

[0013] 0.1-1 parts of initiator, wherein the initiator is a redox initiation system composed of persulfate and sulfite, with a molar ratio of 1:0.5-1:1.5. This initiation system can initiate polymerization reaction at room temperature, making the preparation process of hydrogel more mild and controllable, and avoiding the influence of high temperature on monomer structure and properties.

[0014] 50-100 parts of water, wherein the water is deionized water that has undergone multi-stage reverse osmosis and ion exchange treatment to ensure that the impurity content in the water is less than 1 ppm, so as to avoid the impurities from adversely affecting the performance of the hydrogel and to ensure the purity and stability of the hydrogel, thereby obtaining a hydrophobic hydrogen bond-reinforced hydrogel with high strength, high elasticity and good stability.

[0015] Preferably, the hydrophilic monomer is a carboxyl polyethylene glycol hydroxy monomer or a hydroxyl-polyethylene glycol-carboxyl monomer.

[0016] Preferably, the hydrophobic monomer is octyl acrylate or hexadecyl acrylate.

[0017] Preferably, the crosslinking agent is a trifunctional aziridine crosslinking agent XT-630 or a hexafunctional aziridine crosslinking agent SR-633.

[0018] Preferably, the initiator is a potassium persulfate-sodium sulfite initiation system or an ammonium persulfate-sodium bisulfite initiation system.

[0019] A method for preparing a hydrophobic hydrogen bond-reinforced hydrogel includes the following steps:

[0020] Step 1: Dissolve the hydrophilic monomer, hydrophobic monomer, crosslinking agent and initiator in water, and stir evenly under nitrogen protection to obtain a mixed solution;

[0021] Step 2: Heat the mixed solution to 40-80℃ and react for 2-8 hours to obtain the hydrogel precursor;

[0022] Step 3: Soak the hydrogel precursor in water for 12-48 hours, then dry it to obtain a hydrophobic hydrogen bond-reinforced hydrogel.

[0023] As a preferred embodiment, the stirring time under nitrogen protection is 10-60 minutes.

[0024] As a preferred embodiment, the drying temperature is 40-60℃ and the drying time is 12-72 hours.

[0025] The advantages of this invention are as follows: The hydrophobic hydrogen-bonded reinforced hydrogel prepared by this invention exhibits excellent mechanical properties, with a tensile strength ranging from 1.2 to 2.2 MPa, representing a significant improvement over existing technologies. This is due to the hydrophobic interactions and hydrogen bonds formed between specific hydrophilic and hydrophobic monomers, which, combined with a crosslinking agent, construct a stable three-dimensional network. In biomedical tissue engineering scaffold applications, this network reliably supports cell growth and tissue repair, preventing breakage and damage. The elongation at break is 750%-1250%, far exceeding the 300% of existing technologies. The unique formulation and process endow the hydrogel with good elasticity and plasticity, enabling it to adapt to complex deformations and improve stability and lifespan in the fields of flexible electronic devices and wearable devices.

[0026] The hydrogel exhibits excellent temperature and humidity resistance. After being placed in an environment of 50℃ and 80% humidity for 10 days, the structure of the hydrogel remains intact with a mass loss rate of 1.8%-6.1%, while the structure of the comparative sample is loose. This is due to the synergistic effect of hydrophilic and hydrophobic monomers and the stability of the cross-linking network, which enables it to resist moisture erosion and thermal damage. It has potential applications in tropical outdoor products, high-temperature and high-humidity industrial sensors, and other fields.

[0027] The preparation process of this invention is flexible and controllable. The ratio of hydrophilic and hydrophobic monomers, the amount of crosslinking agent and initiator, the reaction and drying conditions can all be adjusted, and high-performance hydrogels can be produced. It can be optimized and customized as needed. In contrast to the simple process with fixed proportions, it is conducive to large-scale industrial production, reduces costs and improves efficiency. It also lays the foundation for the development of hydrogels with different properties and has broad application prospects and development potential. Attached Figure Description

[0028] Figure 1 This is a bar chart comparing the tensile strength of Examples 1-5 and the comparative examples.

[0029] Figure 2 This is a bar chart comparing the elongation at break of Examples 1-5 and the comparative examples.

[0030] Figure 3 This is a bar chart comparing the mass loss rates of Examples 1-5 and the comparative examples in high temperature and high humidity environments. Detailed Implementation

[0031] For the purposes of the detailed description below, it should be understood that the invention may take various alternative variations and sequences of steps unless expressly stated otherwise. Furthermore, except in any operational instance, or otherwise indicated, all figures representing the amounts of ingredients used, for example, in the specification and claims, should be understood to be modified in all cases by the term “about.” Therefore, unless indicated to the contrary, the numerical parameters set forth in the following specification and appended claims are approximations varying with the desired performance to be obtained according to the invention. It is not at all an attempt to limit the application of the doctrine of equivalents to the scope of the claims; each numerical parameter should be interpreted at least according to the number of significant figures reported and by applying ordinary rounding techniques.

[0032] Although the numerical ranges and parameters illustrating the broad scope of the invention are approximate, the values ​​listed in the specific examples are reported as precisely as possible. However, any numerical value inherently contains some error that is necessarily caused by the standard deviation found in their respective test measurements.

[0033] Furthermore, it should be understood that any numerical range described herein is intended to include all subranges falling within it. For example, the range “1 to 10” is intended to include all subranges between the minimum value 1 and the maximum value 10, i.e., a minimum value equal to or greater than 1 and a maximum value equal to or less than 10.

[0034] Example 1:

[0035] Raw material formula: 45 parts of hydrophilic monomer (carboxylated polyethylene glycol hydroxy monomer), 15 parts of hydrophobic monomer (octyl acrylate), 1 part of crosslinking agent (trifunctional aziridine crosslinking agent XT-630), 0.3 parts of initiator (potassium persulfate-sodium sulfite initiation system), and 50 parts of water.

[0036] Preparation process: The above raw materials were stirred for 20 minutes under nitrogen protection to make them uniformly mixed, and then heated to 40°C and reacted for 4 hours to obtain a hydrogel precursor. After soaking the precursor in water for 24 hours, it was dried at 45°C for 30 hours to obtain a hydrophobic hydrogen bond-reinforced hydrogel.

[0037] Test results: The hydrogel has a tensile strength of 1.5 MPa, an elongation at break of 830%, and remains structurally intact after being placed in a high temperature and high humidity environment of 50℃ (humidity 80%) for 10 days, with a mass loss rate of 4.8%.

[0038] Example 2:

[0039] Raw material formula: 60 parts of hydrophilic monomer (hydroxyl-polyethylene glycol-carboxyl monomer), 20 parts of hydrophobic monomer (hexadecyl acrylate), 3 parts of crosslinking agent (hexafunctional aziridine crosslinking agent SR-633), 0.5 parts of initiator (ammonium persulfate-sodium bisulfite initiation system), and 70 parts of water.

[0040] Preparation process: Stir for 30 minutes under nitrogen protection, react at 80℃ for 2 hours, soak in water for 12 hours, and dry at 50℃ for 40 hours.

[0041] Test results: The hydrogel has a tensile strength of 1.8 MPa, an elongation at break of 920%, and remains structurally intact after being placed in a high temperature and high humidity environment of 50℃ (humidity 80%) for 10 days, with a mass loss rate of 3.9%.

[0042] Example 3:

[0043] Raw material formula: 35 parts of hydrophilic monomer (carboxylated polyethylene glycol hydroxy monomer), 10 parts of hydrophobic monomer (octyl acrylate), 5 parts of crosslinking agent (trifunctional aziridine crosslinking agent XT-630), 0.1 parts of initiator (potassium persulfate-sodium sulfite initiation system), and 55 parts of water.

[0044] Preparation process: Stirring with nitrogen for 10 minutes, reacting at 45℃ for 8 hours, soaking in water for 18 hours, and drying at 40℃ for 20 hours.

[0045] Test results: The hydrogel has a tensile strength of 1.2 MPa, an elongation at break of 750%, and remains structurally intact after being placed in a high temperature and high humidity environment of 50℃ (humidity 80%) for 10 days, with a mass loss rate of 6.1%.

[0046] Example 4:

[0047] Raw material formula: 30 parts of hydrophilic monomer (hydroxyl-polyethylene glycol-carboxyl monomer), 25 parts of hydrophobic monomer (hexadecyl acrylate), 4 parts of crosslinking agent (hexafunctional aziridine crosslinking agent SR-633), 1 part of initiator (ammonium persulfate-sodium bisulfite initiation system), and 100 parts of water.

[0048] Preparation process: Stirring under nitrogen for 60 minutes, reacting at 70℃ for 6 hours, soaking in water for 48 hours, and drying at 60℃ for 12 hours.

[0049] Test results: The hydrogel has a tensile strength of 2.0 MPa, an elongation at break of 1080%, and remains structurally intact after being placed in a high temperature and high humidity environment of 50℃ (humidity 80%) for 10 days, with a mass loss rate of 3.0%.

[0050] Example 5:

[0051] Raw material formula: 55 parts of hydrophilic monomer (carboxylated polyethylene glycol hydroxy monomer), 30 parts of hydrophobic monomer (octyl acrylate), 4.5 parts of crosslinking agent (trifunctional aziridine crosslinking agent XT-630), 0.9 parts of initiator (potassium persulfate-sodium sulfite initiation system), and 90 parts of water.

[0052] Preparation process: Stirring under nitrogen for 50 minutes, reacting at 75°C for 7 hours, soaking in water for 42 hours, and drying at 60°C for 72 hours.

[0053] Test results: The hydrogel has a tensile strength of 2.2 MPa, an elongation at break of 1250%, and remains structurally intact after being placed in a high temperature and high humidity environment of 50℃ (humidity 80%) for 10 days, with a mass loss rate of 1.8%.

[0054] Comparative example:

[0055] Raw material formula: 40 parts of common hydrophilic monomer (polyvinyl alcohol, degree of polymerization 1700), 8 parts of hydrophobic monomer (ethyl butyrate), 3 parts of crosslinking agent (glutaraldehyde), 0.6 parts of initiator (ammonium persulfate), and 60 parts of ordinary distilled water.

[0056] Preparation process: Stir at room temperature for 10 minutes, react at 85℃ for 10 hours, and then air dry.

[0057] Test results: The hydrogel has a tensile strength of 0.4 MPa and an elongation at break of 300%. After being placed in a high temperature and high humidity environment of 50℃ (humidity 80%) for 10 days, the structure becomes loose and cannot maintain its original shape, with a mass loss rate of 96%.

[0058] The relevant test results of Examples 1-5 and the comparative examples are shown in Table 1.

[0059] Table 1

[0060]

[0061] Based on the comparison of the above embodiments and comparative examples, the specific advantages of the present invention are as follows:

[0062] Excellent mechanical properties: tensile strength: such as Figure 1 As shown, the hydrogel prepared by this invention has a tensile strength between 1.2 and 2.2 MPa, while the comparative example has a tensile strength of only 0.4 MPa. This is due to the specific hydrophilic monomers (such as carboxylated polyethylene glycol hydroxyl monomers and hydroxy-polyethylene glycol-carboxyl monomers) and hydrophobic monomers (such as octyl acrylate and hexadecyl acrylate) selected in this invention. These monomers can form effective hydrophobic interactions and hydrogen bonds, and together with crosslinking agents (such as trifunctional aziridine crosslinking agent XT-630 and hexafunctional aziridine crosslinking agent SR-633), they construct a stable and robust three-dimensional network structure, which can withstand greater external tensile forces. In practical applications, such as as tissue engineering scaffolds in the biomedical field, it can better support cell growth and tissue repair, is less prone to breakage and damage, and ensures the safety and reliability of its use.

[0063] Elongation at break: such as Figure 2As shown, the elongation at break of the hydrogel of this invention is 750%-1250%, significantly higher than the 300% of the comparative example. This high elongation at break indicates that the hydrogel possesses excellent flexibility and stretchability. This is because the unique raw material formulation and preparation process of this invention give the hydrogel network structure good elasticity and plasticity, enabling it to maintain structural integrity under significant deformation. In applications such as flexible electronic devices and wearable devices, this high flexibility allows the hydrogel to better adapt to various complex deformation requirements, improving the stability and lifespan of the devices.

[0064] Good resistance to temperature and humidity: such as Figure 3 As shown, after being placed in a high-temperature and high-humidity environment of 50°C (80% humidity) for 10 days, the hydrogels of Examples 1-5 maintained their structural integrity with a mass loss rate of 1.8%-6.1%, while the comparative examples showed a loose structure that could not maintain its original shape. This is because the synergistic effect of the hydrophilic and hydrophobic monomers and the stability of the cross-linked network in this invention enable the hydrogel to effectively resist the erosion of moisture and the damage to the structure caused by thermal motion under high-temperature and high-humidity conditions, thereby maintaining good physical properties and chemical stability. This temperature and humidity resistance makes the hydrogel potentially valuable in fields such as outdoor products in tropical regions and industrial sensors in high-temperature and high-humidity environments, thus broadening its application scope.

[0065] The preparation process is flexible and controllable: Examples of this invention demonstrate various raw material formulations and corresponding changes in preparation process parameters. For instance, the ratio of hydrophilic to hydrophobic monomers, the amount of crosslinking agent and initiator, reaction temperature, time, and stirring and drying conditions can all be adjusted within a certain range, and all yield hydrogels with excellent performance. This indicates that the preparation process of this invention has strong flexibility and controllability, and can be optimized and customized according to actual production needs and product performance requirements. In contrast, comparative preparation processes are relatively fixed and simple, lacking the ability to precisely control product performance and failing to meet the diverse application requirements. This flexible and controllable preparation process facilitates large-scale industrial production, reduces production costs, and improves production efficiency, while also providing a foundation for further research and development of hydrogel materials with different properties.

[0066] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A hydrophobic hydrogen bond-reinforced hydrogel, characterized in that, It is prepared from the following raw materials in parts by weight: 30-60 parts of hydrophilic monomer, wherein the hydrophilic monomer is a polyol monomer containing carboxyl and hydroxyl groups, the molar ratio of carboxyl to hydroxyl groups is 1:2-1:3, and the degree of polymerization of the hydrophilic monomer is 100-500. 10-30 parts of hydrophobic monomer, wherein the hydrophobic monomer is a long-chain alkyl acrylate monomer with an alkyl chain length of 8-16 carbon atoms; 1-5 parts of crosslinking agent, wherein the crosslinking agent is an aziridine compound with multiple functional groups and a functionality of 3-6; 0.1-1 parts of initiator, wherein the initiator is a redox initiation system composed of persulfate and sulfite, and the molar ratio of the two is 1:0.5-1:1.5; 50-100 parts water, which is deionized water that has undergone multi-stage reverse osmosis and ion exchange treatment to ensure that the impurity content in the water is less than 1 ppm.

2. The hydrophobic hydrogen bond-reinforced hydrogel according to claim 1, characterized in that, The hydrophilic monomer is a carboxyl polyethylene glycol hydroxy monomer or a hydroxyl-polyethylene glycol-carboxyl monomer.

3. The hydrophobic hydrogen bond-reinforced hydrogel according to claim 1, characterized in that, The hydrophobic monomer is octyl acrylate or hexadecyl acrylate.

4. The hydrophobic hydrogen bond-reinforced hydrogel according to claim 1, characterized in that, The crosslinking agent is either the trifunctional aziridine crosslinking agent XT-630 or the hexafunctional aziridine crosslinking agent SR-633.

5. The hydrophobic hydrogen bond-reinforced hydrogel according to claim 1, characterized in that, The initiator is a potassium persulfate-sodium sulfite initiation system or an ammonium persulfate-sodium bisulfite initiation system.

6. A method for preparing a hydrophobic hydrogen bond-reinforced hydrogel as described in any one of claims 1-5, characterized in that, The following steps are involved: Step 1: Dissolve the hydrophilic monomer, hydrophobic monomer, crosslinking agent and initiator in water, and stir evenly under nitrogen protection to obtain a mixed solution; Step 2: Heat the mixed solution to 40-80℃ and react for 2-8 hours to obtain the hydrogel precursor; Step 3: Soak the hydrogel precursor in water for 12-48 hours, then dry it to obtain a hydrophobic hydrogen bond-reinforced hydrogel.

7. The preparation method according to claim 6, characterized in that, The stirring time under nitrogen protection is 10-60 minutes.

8. The preparation method according to claim 6, characterized in that, The drying temperature is 40-60℃, and the drying time is 12-72 hours.

Images