Water-retaining hydrogel based on super-hydrophilic polymer as well as preparation method and application of water-retaining hydrogel
The water-retaining hydrogel formed by superhydrophilic polymers and cross-linkers solves the problem of water evaporation in hydrogel sensors during long-term use, maintains conductivity and flexibility, adapts to complex environments, and expands the scope of application.
Patent Information
- Application Number
- CN202510888729.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-30
- Publication Date
- 2025-09-23
AI Technical Summary
Existing hydrogel sensors are easily affected by the rapid evaporation of water during long-term use, which affects their sensitivity and mechanical properties. Existing water retention methods may also impair conductivity or flexibility.
Superhydrophilic polymers are used as the main network and combined with cross-linker units to form a water-retaining hydrogel with superhydrophilic properties, enhance the interaction between the hydrogel and water molecules, and maintain good conductivity, flexibility and biocompatibility.
It has achieved the extension of stable sensing capabilities in complex environments, expanded the application scope of hydrogel sensors in the field of flexible electronics, and has excellent water retention, conductivity and flexibility while maintaining good biocompatibility.
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Figure CN120682406A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of polymer materials, and particularly relates to a water-retaining hydrogel based on a super-hydrophilic polymer, and a preparation method and application thereof. Background Art
[0002] In recent years, with the rapid development of wearable technology, flexible sensors, as an important technical means, have shown great application prospects in the fields of medicine, bionics and flexible electronics. Flexible wearable sensors are able to detect a wide range of physical and chemical signals and show remarkable adaptability to various forms. Generally speaking, flexible sensors can be divided into two categories: one is electronic sensors based on elastomers, such as polydimethylsiloxane (PDMS), polyurethane (PU) or polyester (PET); the other is ion sensors developed from hydrogels. Compared with traditional electronic sensors, the ionic conductivity of hydrogels is particularly suitable for advanced mechanical, chemical and electrical sensing of physiologically relevant signals. In addition, hydrogel-based ion sensors do not require complex electrodes or other external circuit components, which simplifies the manufacturing process and exhibits excellent biocompatibility and adjustable mechanical adaptability.
[0003] Despite their many advantages, hydrogel sensors are often affected by rapid evaporation of water, which may affect their sensitivity and mechanical properties. To address the problem of long-term water loss, two main strategies have been adopted: preventing solvent evaporation and integrating protective layers. For example, replacing water with organic solvents can create organic hydrogels with excellent antifreeze and non-drying properties; while protective layers, such as elastomers or composite coatings, exhibit significant stretchability and water retention. However, these methods still have some problems, such as organic solvents may have a negative impact on the conductivity of hydrogels, and internal cross-linked protective layers may affect the flexibility and integrity of hydrogels under large deformations.
[0004] Therefore, developing a hydrogel with good water retention, good conductivity, flexibility and biocompatibility is an urgent problem to be solved in this field. Summary of the Invention
[0005] To address the shortcomings of the prior art, the present invention aims to provide a water-retaining hydrogel based on a superhydrophilic polymer, as well as its preparation method and application. This hydrogel addresses the existing problem of hydrogel sensors lacking high water retention, good conductivity, and flexibility. It offers excellent sensing performance and biocompatibility, and can be used in wearable devices or human body monitoring.
[0006] To achieve this object, the present invention adopts the following technical solutions:
[0007] In a first aspect, the present invention provides a water-retaining hydrogel based on a superhydrophilic polymer, the water-retaining hydrogel comprising a superhydrophilic polymer unit and a unit derived from a cross-linking agent.
[0008] In the present invention, the superhydrophilic polymer main unit is the main network of the water-retaining hydrogel, and the unit derived from the cross-linking agent is used to maintain the network structure; wherein, its water-retaining performance mainly comes from the superhydrophilic polymer constituting the main body of the network. Through the superhydrophilic property of the superhydrophilic polymer, the interaction between water in the hydrogel and the gel network is increased, on the one hand, it makes it difficult for water to escape from the gel network, and on the other hand, it can capture free water molecules in the environment, thereby giving it excellent water-retaining ability; in addition, the water-retaining hydrogel also maintains the inherent flexibility, conductivity and biocompatibility of the hydrogel, has good universality, and can adapt to various complex conditions. It not only helps to extend the service life of the sensor, but also can maintain its stable sensing ability under various complex environmental conditions, further expanding the application scope of hydrogel sensors in the field of flexible electronics.
[0009] Preferably, the molecular structure of the polymerized monomer of the super-hydrophilic polymer unit contains a carbon-carbon double bond and a hydrophilic group.
[0010] Preferably, the hydrophilic group includes at least one of a hydroxyl group, a carboxyl group, an amino group, a carboxylate ion, a sulfonate ion or an ammonium ion.
[0011] Preferably, the polymerized monomer of the super-hydrophilic polymer unit includes at least one of an acrylate compound, a sulfonate compound or a quaternary ammonium salt compound.
[0012] Preferably, the acrylate compound includes at least one of sodium acrylate, aluminum acrylate, lithium acrylate or sodium methacrylate.
[0013] Preferably, the sulfonate compound includes 2-acrylamido-2-methylpropanesulfonic acid sodium salt and / or 3-[N,N-dimethyl-[2-(2-methylprop-2-enoyloxy)ethyl]ammonium]propane-1-sulfonic acid inner salt.
[0014] Preferably, the quaternary ammonium salt compound includes at least one of acryloyloxyethyltrimethylammonium chloride, (3-acrylamidopropyl)trimethylammonium chloride or methacryloyloxyethyltrimethylammonium chloride.
[0015] Preferably, the number of carbon-carbon double bonds in the molecular structure of the cross-linking agent is ≥2, for example, it can be 2, 3, 4, 5, 6, 7, 8, 9, etc.
[0016] Preferably, the crosslinking agent includes at least one of N,N′-methylenebisacrylamide, ethylene glycol dimethacrylate, N,N′,N″-triacryloyldiethylenetriamine or triallyl isocyanurate.
[0017] Preferably, the molar content of the cross-linking agent is 0.05-0.3% of the total molar content of the polymerized monomers of the super hydrophilic polymer unit, for example, it can be 0.05%, 0.06%, 0.08%, 0.1%, 0.12%, 0.14%, 0.16%, 0.18%, 0.2%, 0.22%, 0.24%, 0.26%, 0.28%, 0.3%, etc.
[0018] In a second aspect, the present invention provides a method for preparing the water-retaining hydrogel based on a super-hydrophilic polymer according to the first aspect, the preparation method comprising the following steps:
[0019] The polymerizable monomers and the cross-linking agent are mixed and reacted to obtain the water-retaining hydrogel based on the super-hydrophilic polymer.
[0020] Preferably, the mixed raw materials further include an initiator.
[0021] Preferably, the molar content of the initiator is 0.05-0.3% of the total molar content of the polymerized monomers of the superhydrophilic polymer unit, for example, it can be 0.05%, 0.06%, 0.08%, 0.1%, 0.12%, 0.14%, 0.16%, 0.18%, 0.2%, 0.22%, 0.24%, 0.26%, 0.28%, 0.3%, etc.
[0022] Preferably, the initiator includes at least one of ammonium persulfate, lithium phenyl (2,4,6-trimethylbenzoyl) phosphate, azobisisobutylcyanide, benzophenone, 4,4'-azobis (4-cyanovaleric acid), and azobisisobutylamidine hydrochloride.
[0023] Preferably, the mixing is performed in a solvent, and the solvent comprises water.
[0024] Preferably, the content of the solvent is such that the concentration of the polymerizable monomer is 1 to 5 mol / L, for example, 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L, 5 mol / L, etc.
[0025] Preferably, the reaction is carried out under heating or light conditions, and the reaction time is 4 to 10 hours, for example, 4 hours, 5 hours, 6 hours, 8 hours, 10 hours, etc.
[0026] In the present invention, as a preferred technical solution, the preparation method includes: mixing a polymerizable monomer and a cross-linking agent with water to obtain a mixed solution; removing oxygen from the obtained mixed solution with argon gas, and then adding an initiator thereto to obtain a gel precursor solution; then transferring the obtained gel precursor solution to a mold, and gelling it under light or heating conditions for 1 to 10 hours to obtain the water-retaining hydrogel based on the superhydrophilic polymer.
[0027] In a third aspect, the present invention provides an application of the water-retaining hydrogel based on superhydrophilic polymer described in the first aspect in the fields of flexible electronic devices, wearable devices, electronic skin, and long-term human body monitoring.
[0028] In the present invention, the water-retaining hydrogel based on the superhydrophilic polymer contains conductive ions, and therefore can be used in flexible electronic devices, wearable devices, electronic skin, long-term human body monitoring, etc.
[0029] The numerical range described in the present invention includes not only the point values listed above, but also any point values between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values included in the range.
[0030] Compared with the prior art, the present invention has the following beneficial effects:
[0031] The water-retaining hydrogel of the superhydrophilic polymer provided by the present invention is composed of a main network of superhydrophilic polymer units and units derived from a cross-linking agent that maintain the network structure. It has excellent water-retaining capacity while maintaining the inherent flexibility, conductivity and biocompatibility of the hydrogel. It has good universality and can adapt to various complex conditions. It not only helps to extend the service life of the sensor, but also can maintain its stable sensing ability under various complex environmental conditions, further expanding the application scope of hydrogel sensors in the field of flexible electronics. BRIEF DESCRIPTION OF THE DRAWINGS
[0032] Figure 1 The hydrogels provided in Example 1 and Comparative Example 1 of the present invention were placed at room temperature (25° C.) and 50% humidity for 24 hours, and the appearance of the hydrogels at different time periods were shown.
[0033] Figure 2 The hydrogel provided in Example 1 of the present invention and Comparative Example 1 is placed at room temperature (25°C) and a humidity of 50% for 48 hours and shows a hydrogel weight percentage data graph.
[0034] Figure 3 This is a tensile stress-strain curve diagram of the hydrogel provided in Example 1 of the present invention and Comparative Example 1.
[0035] Figure 4 This is a compressive stress-strain curve diagram of the hydrogel provided in Example 1 of the present invention and Comparative Example 1.
[0036] Figure 5 This is a graph of the tensile and compressive breaking strain data of the hydrogels provided in Example 1 of the present invention and Comparative Example 1.
[0037] Figure 6Graph showing the tensile and compressive modulus data of the hydrogels provided in Example 1 of the present invention and Comparative Example 1.
[0038] Figure 7 Schematic diagram of the design of the hydrogel sensor;
[0039] in, Figure 7 A is a schematic diagram of a basic resistance sensor for temperature and strain sensing; Figure 7 B is a schematic diagram of finger and elbow flexion movements.
[0040] Figure 8 Graph showing relative resistance changes of the hydrogel sensors provided in Example 1 and Comparative Example 1 of the present invention under variable temperature cycles of 25-30°C, 25-35°C, and 25-40°C;
[0041] in, Figure 8 A is a graph showing the relative resistance change of the hydrogel sensor provided in Example 1 of the present invention at different cycle temperatures; Figure 8 B is a graph showing the relative resistance change of the hydrogel sensor provided in Comparative Example 1 at different cycle temperatures.
[0042] Figure 9 Graph showing changes in relative resistance of the hydrogel sensors provided in Example 1 and Comparative Example 1 of the present invention during long-term monitoring of circulating human motion in air;
[0043] in, Figure 9 A is the relative resistance change diagram during long-term monitoring of finger bending movement; Figure 9 B is the graph of relative resistance changes during long-term monitoring of elbow flexion movement.
[0044] Figure 10 This is a diagram showing the cell compatibility test results of the hydrogels provided in Example 1 and Comparative Example 1 of the present invention.
[0045] Figure A shows a live / dead staining of hMSC cells after 24 hours of culture in PAAm and PNaAAc hydrogels. Figure B shows a bar graph of cell viability after 24 hours of co-culture with PAAm and PNaAAc, respectively. Figure C shows a live / dead staining of huh-7 cells after 24 hours of culture in PAAm and PNaAAc hydrogels. Figure D shows a bar graph of cell viability after 24 hours of co-culture with PAAm and PNaAAc, respectively. DETAILED DESCRIPTION
[0046] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.
[0047] Example 1
[0048] This embodiment provides a water-retaining hydrogel based on a superhydrophilic polymer, comprising a superhydrophilic polymer unit and a unit derived from a cross-linking agent; the polymerization monomer of the superhydrophilic polymer unit is sodium acrylate (NaAAc); the cross-linking agent is N,N′-methylenebisacrylamide; the molar content of the cross-linking agent is 0.1% of the total molar content of the polymerization monomers; and the initiator in the raw materials for preparing the water-retaining hydrogel is lithium phenyl (2,4,6-trimethylbenzoyl) phosphate, and the molar content of the initiator is 0.1% of the total molar content of the polymerization monomers.
[0049] This embodiment provides a method for preparing a water-retaining hydrogel based on a super-hydrophilic polymer, which specifically comprises the following steps:
[0050] The polymerization monomer and the cross-linking agent are mixed with water to obtain a mixed solution, wherein the concentration of the polymerization monomer in the mixed solution is 3M and the concentration of the cross-linking agent is 3mM; after removing oxygen from the obtained mixed solution with argon gas, the initiator phenyl (2,4,6-trimethylbenzoyl) lithium phosphate is added thereto to obtain a gel precursor solution (the concentration of the initiator in the gel precursor solution is 3mM); then the obtained gel precursor solution is transferred to a mold and gelled under light conditions for 6 hours to obtain the water-retaining hydrogel based on the super hydrophilic polymer.
[0051] Comparative Example 1
[0052] This comparative example provides a hydrogel, which differs from Example 1 only in that sodium acrylate is replaced by an equimolar amount of acrylamide (AAm), and the other raw materials, amounts used, and preparation methods are the same as those in Example 1.
[0053] Performance Testing
[0054] Taking the superhydrophilic polymer-based water-retaining hydrogel (PNaAAc) provided in Example 1 and the hydrogel (PAAm) provided in Comparative Example 1 as examples, the water retention, mechanical properties, sensing properties and biocompatibility of the hydrogels were tested, as follows.
[0055] (1) Water retention performance test.
[0056] PNaAAc and PAAm were placed at room temperature (25°C) and humidity of 50% for a period of time, and the dehydration of the hydrogel was observed and the mass of the hydrogel at different times was recorded; among them, after PNaAAc and PAAm were placed at room temperature (25°C) and humidity of 50% for 6 hours and 24 hours respectively, the appearance of the hydrogel was as follows: Figure 1 As shown; the weight of the hydrogels of PNaAAc and PAAm placed at room temperature (25°C) and humidity of 50% within 48 hours was normalized, and the remaining mass percentage of the hydrogel at different times was as shown Figure 2 shown.
[0057] Depend on Figure 1 It can be seen that the hydrogel provided in Comparative Example 1 has been significantly dehydrated after being placed for 6 hours, and the dehydration is further aggravated after being placed for 24 hours. However, the water-retaining hydrogel provided by the present invention has only been dehydrated to a lesser extent after being placed for 24 hours; and Figure 2 It can be seen that within 6 hours, the weight ratio (normalized residual mass) of the water-retaining hydrogel provided by the present invention is about 71.3%, while the weight ratio of the hydrogel provided in Comparative Example 1 is about 23.7%; in summary, it is shown that the water-retaining hydrogel based on the super hydrophilic polymer provided by the present invention has better water retention performance under the same conditions.
[0058] (2) Mechanical properties test
[0059] The tensile properties of PNaAAc and PAAm were tested using a tensile testing machine (tensile stress-strain curves are shown in Figure 2). Figure 3 shown) and compression properties (compression stress-strain curves as shown Figure 4 The tensile and compressive fracture strains of PNaAAc and PAAm were calculated (the results are shown in Figure 5 ) and Young's modulus (results as shown Figure 6 shown).
[0060] Depend on Figure 3 、 Figure 4 and Figure 5 It can be seen that the water-retaining hydrogel provided by the present invention exhibits a fracture strain of 714.5% and a fracture stress of 103.2 kPa under tension, and a fracture strain and fracture stress of 77.1% and 0.784 MPa under compression; it has higher tensile and compressive fracture strains and fracture stresses than PAAm; and Figure 6 It can be seen that the water-retaining hydrogel provided by the present invention has higher tensile and compression moduli; this shows that the water-retaining hydrogel provided by the present invention has better mechanical properties and can better ensure ductility and integrity during dynamic deformation; this is because there are anions and cations in the PNaAAc hydrogel, and there is electrostatic interaction between the hydrogel network, so the PNaAAc hydrogel has a relatively higher Young's modulus and fracture strain.
[0061] (3) Sensing performance test
[0062] The present invention has carried out the temperature and stress cycle sensing performance test on PAAm and PNaAAc; Figure 7 Schematic diagram of the design of the hydrogel sensor. Figure 7 A is a schematic diagram of a basic resistance sensor for temperature and strain sensing; Figure 7B is a schematic diagram of finger and elbow bending movements. To enable sensing, salt ions (1M) were added to the PAAm sample to make it conductive. Since the PNaAAc hydrogel already has ions, no additional treatment was performed.
[0063] Since the resistance of the hydrogel is affected by temperature, the relative resistance change (ΔR / R0) of the PAAm and PNaAAc hydrogel sensors under variable temperature cycles of 25-30°C, 25-35°C, and 25-40°C was first tested to verify their tolerance to body temperature. Each temperature cycle was repeated 10 times. The results are shown in Figure 2. Figure 8 shown; among them, Figure 8 A is the relative resistance change diagram of PNaAAc hydrogel sensor at different cycle temperatures; Figure 8 B is the relative resistance change diagram of PAAm hydrogel sensor at different cycle temperatures; Figure 8 A and Figure 8 As shown in Figure B, after 10 cycles, the resistance change of the PNaAAc hydrogel sensor remained stable with a baseline deviation of less than 8%, while the baseline deviation of the PAAm hydrogel sensor was significant (approximately 69.7%).
[0064] PAAm and PNaAAc hydrogel sensors were used to monitor human motion in air for a long time. Figure 9 As shown in the figure, PNaAAc and PAAm hydrogel sensors are used to monitor finger bending movements for a long time, and the relative resistance change is shown in the figure. Figure 9 As shown in A; PNaAAc and PAAm hydrogel sensors are used to monitor elbow flexion for a long time. The relative resistance change is shown in Figure 9 As shown in B; Figure 9 As shown in Figures A and 9B, the water-retaining hydrogel sensor provided by the present invention exhibited stable and distinguishable sensing signals for finger and elbow flexion over a 2-hour period, with the baseline remaining virtually unchanged. In stark contrast, the PAAm hydrogel sensor's sensing signal decreased by 83.7% over the same period.
[0065] (4) Cytocompatibility test
[0066] Mesenchymal stem cells (hMSCs) and human hepatoma cells (huh-7) were co-cultured with PAAm and PNaAAc to evaluate their cytocompatibility. 4 ) and co-cultured at 37°C and 5% CO2. After 24 h of culture, cell viability was assessed using a live / dead cell viability / cytotoxicity kit (Calcein-AM / PI double staining kit). Figure 10Figure 1 shows live (upper) and dead (lower) staining of hMSC cells after 24 hours of culture in PAAm and PNaAAc hydrogels. Figure 1 shows live (upper) and dead (lower) staining of hMSC cells after 24 hours of co-culture with PAAm and PNaAAc hydrogels. Figure 1 shows live (upper) and dead (lower) staining of huh-7 cells after 24 hours of culture in PAAm and PNaAAc hydrogels. Figure 1 shows live (upper) and dead (lower) staining of huh-7 cells after 24 hours of co-culture with PAAm and PNaAAc hydrogels. Figure 1 shows live (upper) and dead (lower) staining of huh-7 cells after 24 hours of co-culture with PAAm and PNaAAc hydrogels. Figure 1 shows live (upper) and dead (lower) staining of huh-7 cells after 24 hours of co-culture with PAAm and PNaAAc hydrogels. Control represents a blank control group in which hMSC and huh-7 cells were cultured in cell culture medium for 24 hours.
[0067] Depend on Figure 10 It can be seen that after 24 h of co-culture with all hydrogel samples, the normalized cell viability of both hMSC and huh-7 was similar to that of the blank control and close to 100%, indicating that the water-retaining hydrogel based on superhydrophilic polymer in the present invention has good cell compatibility and no cytotoxicity.
[0068] The applicant declares that the above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the scope of protection and disclosure of the present invention.
Claims
1. A water-retaining hydrogel based on a super-hydrophilic polymer, characterized in that: The water-retaining hydrogel includes superhydrophilic polymer units and units derived from a cross-linking agent.
2. The water-retaining hydrogel according to claim 1, characterized in that The molecular structure of the polymerized monomer of the super-hydrophilic polymer unit contains a carbon-carbon double bond and a hydrophilic group; Preferably, the hydrophilic group includes at least one of a hydroxyl group, a carboxyl group, an amino group, a carboxylate ion, a sulfonate ion or an ammonium ion.
3. The water-retaining hydrogel according to claim 1 or 2, characterized in that The polymerized monomer of the super-hydrophilic polymer unit includes at least one of an acrylate compound, a sulfonate compound or a quaternary ammonium salt compound.
4. The water-retaining hydrogel according to claim 3, characterized in that The acrylate compound includes at least one of sodium acrylate, aluminum acrylate, lithium acrylate or sodium methacrylate; Preferably, the sulfonate compound includes 2-acrylamido-2-methylpropanesulfonic acid sodium salt and / or 3-[N,N-dimethyl-[2-(2-methylprop-2-enoyloxy)ethyl]ammonium]propane-1-sulfonic acid inner salt; Preferably, the quaternary ammonium salt compound includes at least one of acryloyloxyethyltrimethylammonium chloride, (3-acrylamidopropyl)trimethylammonium chloride or methacryloyloxyethyltrimethylammonium chloride.
5. The water-retaining hydrogel according to any one of claims 1 to 4, characterized in that The number of carbon-carbon double bonds in the molecular structure of the cross-linking agent is ≥2; Preferably, the crosslinking agent includes at least one of N,N′-methylenebisacrylamide, ethylene glycol dimethacrylate, N,N′,N″-triacryloyldiethylenetriamine or triallyl isocyanurate.
6. The water-retaining hydrogel according to any one of claims 1 to 5, characterized in that The molar content of the cross-linking agent is 0.05-0.3% of the total molar content of the polymerized monomers of the super-hydrophilic polymer unit.
7. A method for preparing a water-retaining hydrogel based on a super-hydrophilic polymer according to any one of claims 1 to 6, characterized in that: The preparation method comprises the following steps: The polymerizable monomers and the cross-linking agent are mixed and reacted to obtain the water-retaining hydrogel based on the super-hydrophilic polymer.
8. The preparation method according to claim 7, characterized in that The mixed raw materials also include an initiator; Preferably, the molar content of the initiator is 0.05 to 0.3% of the total molar content of the polymerized monomers of the super-hydrophilic polymer unit; Preferably, the initiator includes at least one of ammonium persulfate, lithium phenyl (2,4,6-trimethylbenzoyl) phosphate, azobisisobutylcyanide, benzophenone, 4,4'-azobis (4-cyanovaleric acid), and azobisisobutylamidine hydrochloride.
9. The preparation method according to claim 7 or 8, characterized in that The mixing is carried out in a solvent, and the solvent includes water; Preferably, the content of the solvent is such that the concentration of the polymerizable monomer is 1 to 5 mol / L; Preferably, the reaction is carried out under heating or light conditions, and the reaction time is 4 to 10 hours.
10. Use of the water-retaining hydrogel based on a superhydrophilic polymer according to any one of claims 1 to 6 in the fields of flexible electronic devices, wearable devices, electronic skin, and long-term human body monitoring.