A hydrogel based on single-chain nanoparticle topological entanglement and a preparation method thereof

Abstract

The application discloses a kind of hydrogel based on single-chain nanoparticle topological entanglement and preparation method thereof, belong to the technical field of polymer hydrogel material mechanics enhancement, precursor chain monomer is copolymerized with 4-acryloyloxy benzophenone, acrylamide to prepare precursor chain, then the precursor chain is made into single-chain nanoparticle, and then acrylamide, crosslinking agent, photoinitiator and single-chain nanoparticle are in-situ polymerized to prepare the hydrogel based on single-chain nanoparticle topological entanglement.The hydrogel prepared by the application introduces single-chain nanoparticle as permanent nanoscale topological entanglement unit, forms stable topological interlocking structure in network, thereby significantly improves the strength, toughness, elasticity and fatigue resistance of hydrogel, and realizes low hysteresis (~800%, <5%) and temperature self-adaptive mechanical behavior under large strain.The material prepared by the application is suitable for reversible deformation, energy efficient dissipation and higher environmental adaptability requirement of soft material application scene.

Description

Technical Field

[0001] This invention relates to the field of mechanical enhancement technology for polymer hydrogel materials, specifically to a hydrogel based on the topological entanglement of single-chain nanoparticles and its preparation method. Background Technology

[0002] Hydrogels are soft, wet materials with high water content. Due to their cross-linked three-dimensional network structure, hydrogels can swell in water, efficiently absorbing and retaining large amounts of moisture. Based on these properties, hydrogels play a crucial role in various fields, such as smart sensors, tissue engineering, drug loading, and wound healing. To meet the needs of more applications, hydrogel materials must satisfy a series of interrelated mechanical property requirements: high strength to resist permanent deformation and structural failure, high toughness to inhibit crack initiation and propagation, and low hysteresis to achieve efficient energy cycling and reduce fatigue damage under repeated loading.

[0003] However, in traditional hydrogel systems, there are often profound inherent contradictions among these performance indicators. For example, increasing the density of chemical crosslinking can improve strength, but usually results in a loss of toughness, leading to brittle fracture; introducing energy dissipation units can significantly improve toughness, but often comes with significant hysteresis, affecting the material's durability. The root of this trade-off lies in the fact that the macroscopic mechanical behavior of materials is often controlled by the microstructure within the system, including the multi-scale topology of polymer networks, the dynamic behavior of polymer chains, and the interaction between solvent and polymer. Therefore, starting from the molecular level, the precise design and construction of novel hydrogel networks that can simultaneously meet the above-mentioned high-performance indicators is one of the crucial challenges in the field of soft materials.

[0004] Unlike traditional nanoparticle fillers, single-chain nanoparticles are nanomaterials formed by intramolecular cross-linking of polymer single chains containing cross-linking agents, exhibiting an intramolecular folded structure similar to natural proteins. The main experimental method for synthesizing single-chain nanoparticles is the cross-linking reaction of precursor chains in extremely dilute, good solvents, resulting in a simple preparation process. Due to the vast polymer library and tunable topology of single-chain nanoparticles, they hold promise for mimicking the fibrous structures of biological tissues to prepare composite hydrogel materials with excellent mechanical properties and good biocompatibility. The precursor chains of single-chain nanoparticles are polymer chains; any polymer chain capable of intramolecular cross-linking can be used to prepare single-chain nanoparticles. This gives single-chain nanoparticles a degree of designability and allows for tunable topologies. In summary, based on the characteristics of single-chain nanoparticles, the structures of single-chain nanoparticle composites exhibit good interpretability, making their application in composite materials a promising prospect.

[0005] Traditional methods of reinforcing hydrogels by introducing sacrificial bonds or rigid fillers can improve strength or toughness to some extent, but they usually induce significant irreversible deformation and high hysteresis effects, resulting in low energy dissipation efficiency and limited fatigue life under cyclic loading. The fundamental reason is that traditional chain entanglements in the aquatic environment are mostly transient and cannot form persistent and stable topological constraints in the swollen state for reversible energy dissipation.

[0006] Therefore, how to overcome the inherent contradiction that the mechanical properties of hydrogels are difficult to improve in a synergistic way in the existing technology, and provide a hydrogel based on heterogeneous single-molecule knotted topology engineering, so as to improve the fracture strength, fracture strain, toughness and fatigue resistance of hydrogels in a relaxed and simultaneous manner, is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0007] In view of this, the present invention provides a hydrogel based on the topological entanglement of single-chain nanoparticles. By constructing permanent nanoscale topological entanglements formed by single-chain nanoparticles within the hydrogel network, it simultaneously and significantly improves the fracture strength, fracture strain, toughness, and fatigue resistance of the hydrogel without introducing high hysteresis, and also makes its mechanical properties temperature-adaptive, thereby solving the performance trade-off problem caused by traditional reinforcement strategies. The prepared hydrogel possesses high strength, high toughness, low hysteresis, and temperature-adaptive mechanical properties, making it suitable for flexible sensors, soft robots, tissue engineering scaffolds, and other smart soft materials with high requirements for reversible deformation and energy efficiency.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A method for preparing a hydrogel based on the topological entanglement of single-chain nanoparticles includes the following steps:

[0010] (1) The precursor chain of random copolymer was synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization: the precursor chain monomer, 4-acryloyloxybenzophenone (ABP) and acrylamide (AAM) were mixed, heated and stirred to react, and the product was purified and dried to obtain the precursor chain;

[0011] (2) Synthesis of single-chain nanoparticles: The precursor chain was dispersed in deionized water to obtain a dispersion, and then irradiated with ultraviolet light to induce intramolecular crosslinking. After purification and drying, single-chain nanoparticles were obtained, denoted as SCNPs.

[0012] (3) Preparation of hydrogel: Acrylamide, crosslinking agent, photoinitiator and SCNPs are mixed and added to deionized water and stirred to form a homogeneous solution. Then the solution is injected into a mold and cured by UV irradiation.

[0013] (4) Swelling equilibrium: The solidified hydrogel is immersed in a water bath until swelling equilibrium is reached to obtain a hydrogel based on the topological entanglement of single-chain nanoparticles.

[0014] In this invention, the hydrogel network structure is as follows: SCNPs serve as dynamic cross-linking points and topological "nanojunctions", forming a hybrid network with the polyacrylamide (PAAM) network through physical entanglement.

[0015] The enhancement mechanism is as follows: SCNPs provide additional energy dissipation pathways by absorbing stress through segment slippage and remodeling. In SNAA-gels, precursor chain monomers (such as NIPAM) make SCNPs hydrophilic at low temperatures and hydrophobic at high temperatures, causing network contraction / expansion, regulating mechanical properties, and improving strength and toughness.

[0016] Furthermore, the precursor chain monomer mentioned in step (1) is N-isopropylacrylamide (NIPAM) or N,N-dimethylacrylamide (DMAA).

[0017] Furthermore, the molar ratio of the precursor chain monomer, 4-acryloyloxybenzophenone and acrylamide in step (1) is 15:1:4;

[0018] The heating and stirring reaction temperature is 333-338 K, and the reaction time is 20-24 h.

[0019] Furthermore, the concentration of the precursor chain in the dispersion in step (2) is 1-3 mg / mL;

[0020] The ultraviolet light irradiation wavelength is 365nm, and the irradiation time is 10-12h.

[0021] Furthermore, the crosslinking agent mentioned in step (3) is N,N'-methylenebisacrylamide (MBAA).

[0022] The photoinitiator is 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylacetophenone.

[0023] Furthermore, the amount of crosslinking agent used in step (3) is 0.01-1 wt% of the amount of acrylamide used;

[0024] The amount of photoinitiator used is 0.008-0.012 wt% of the amount of acrylamide used;

[0025] The amount of SCNPs used is 1-5 wt% of the amount of acrylamide used.

[0026] Furthermore, the ultraviolet lamp irradiation wavelength in step (3) is 365nm, and the irradiation time is 3-6h.

[0027] Furthermore, the water bath temperature in step (4) is 278K-318K, and the water bath time is 24-30h.

[0028] The beneficial effects of this invention are as follows:

[0029] (1) Achieved synergistic improvement in mechanical properties, breaking the traditional trade-off relationship: This invention introduces permanent and dynamic topological entanglement (heterogeneous monomolecule knotting) at the molecular scale through single-chain nanoparticles (SCNPs), enabling the hydrogel to simultaneously obtain high fracture strength (>1.2 MPa), extremely high fracture strain (>1200%), and excellent toughness (>4.5 MJ / m²) even at a water content of over 85 wt%. -3 With its ultra-low hysteresis (<5%), it successfully solves the inherent contradiction in traditional hydrogels that it is difficult to achieve both strength, toughness and recoverability.

[0030] (2) Excellent structural durability and fatigue resistance: Thanks to the permanent and reversible sliding properties of topological entanglement, the hydrogel maintains stable mechanical properties and has a very low hysteresis rate after 500 consecutive cycles of loading and unloading at 200% strain, which is significantly better than traditional reinforced hydrogels that rely on irreversible sacrificial bonds, and exhibits excellent structural recoverability and fatigue resistance.

[0031] (3) Intelligent temperature-adaptive mechanical behavior: When thermally responsive (such as NIPAM-based) SCNPs are used, the mechanical properties of the hydrogel, such as modulus and toughness, can be dynamically and reversibly adjusted with the ambient temperature. For example, the material is flexible at low temperatures to efficiently dissipate energy, while it becomes locally stiff at high temperatures to resist deformation, thus realizing the "intelligent" properties of the material and greatly expanding its application potential in fields such as intelligent sensing and actuation.

[0032] (4) Extremely high enhancement efficiency and universality: The enhancement strategy of the present invention has high efficiency and universality. Only a trace amount (e.g., 1 wt%) of SCNPs is needed to achieve a doubling of mechanical properties. In addition, this enhancement mechanism is applicable to SCNPs with different chemical compositions (e.g., thermosensitive NIPAM group and non-thermosensitive DMAA group), indicating that the method has good universality and scalability.

[0033] In summary, the hydrogel of this invention significantly improves the strength, toughness, elasticity, and fatigue resistance of the hydrogel by introducing single-chain nanoparticles with thermally responsive behavior as heterogeneous, permanent nanoscale topological entanglement units, forming a stable monomolecular knotted structure within the network. It also achieves low hysteresis (<5%) and temperature-adaptive mechanical behavior. This material is suitable for soft material applications requiring reversible deformation, efficient energy dissipation, and environmental adaptability, such as flexible sensors, soft robots, tissue engineering scaffolds, and intelligent medical devices. Attached Figure Description

[0034] Figure 1 SNAA single-chain nanoparticles prepared in Example 1 of this invention 1 H NMR spectrum;

[0035] Figure 2 SDAA single-chain nanoparticles prepared in Example 2 of this invention 1 H NMR spectrum;

[0036] Figure 3 The image shows the dynamic light scattering results of the single-chain nanoparticles SNAA prepared according to Example 1, which characterizes the size change with swelling temperature.

[0037] Figure 4 This is a comparison of the mechanical properties of composite hydrogels with different contents of SNAA single-chain nanoparticles prepared according to Example 1;

[0038] Figure 5 The image shows the performance of the 1 wt% SNAA hydrogel swollen at 298K prepared according to Example 1 at room temperature.

[0039] Figure 6 Temperature adaptability diagram of SNAA hydrogel prepared according to Example 1;

[0040] Figure 7 The graph shows the water content of the SNAA hydrogel prepared according to Example 1.

[0041] Figure 8 The image shows the results of 500 cycles of tensile testing on a 1 wt% SNAA hydrogel prepared in Example 1 with a strain of 200%.

[0042] Figure 9 The image shows the results of 10 cycles of tensile testing on a 1 wt% SNAA hydrogel prepared in Example 1 with a strain of 800%.

[0043] Figure 10 The results of single-cycle tensile stress and hysteresis of 1 wt% SNAA hydrogel prepared in Example 1 with strain from 200% to 800% are shown in the figure.

[0044] Figure 11 The image shows the dynamic light scattering results of the SDAA single-chain nanoparticles prepared in Example 2.

[0045] Figure 12 The graph shows a comparison of the mechanical properties of the SDAA single-chain nanoparticle composite hydrogel prepared in Example 2 at different temperatures. Detailed Implementation

[0046] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] Example 1

[0048] A hydrogel based on the topological entanglement of single-chain nanoparticles:

[0049] (1) Synthesis of precursor chain (PNAA): N-isopropylacrylamide, 4-acryloyloxybenzophenone and acrylamide were mixed and heated and stirred at 333-338K for 20-24h. After the product was purified and dried, the precursor chain PNAA was obtained.

[0050] (2) Synthesis of single-chain nanoparticles: The precursor chain was dispersed in deionized water to obtain a dispersion with a concentration of 1-3 mg / mL. Then, it was irradiated with 365 nm ultraviolet light for 10-12 h to induce intramolecular crosslinking. After purification, it was dried to obtain single-chain nanoparticles (SCNPs), which were labeled as SNAA.

[0051] The synthetic route for single-chain nanoparticles is as follows:

[0052]

[0053] Among them, x+y+z=1, x=62.9%, y=8.8%, z=28.3%;

[0054] (3) Preparation of hydrogel: Acrylamide, crosslinking agent N,N'-methylenebisacrylamide, photoinitiator 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylacetophenone and SNAA are mixed and added to deionized water and stirred to form a homogeneous solution. Then, the solution is injected into a mold and cured by irradiation with a 365nm ultraviolet lamp for 3-6 hours to obtain a hydrogel based on the topological entanglement of single-chain nanoparticles (denoted as SNAA hydrogel).

[0055] The crosslinking agent is used at 0.01 wt% of the acrylamide content; the photoinitiator is used at 0.01 wt% of the acrylamide content.

[0056] (4) Swelling equilibrium: Immerse in water baths at different temperatures (278K, 298K, 318K) until swelling equilibrium is reached.

[0057] Example 2

[0058] A hydrogel based on the topological entanglement of single-chain nanoparticles:

[0059] (1) Synthesis of precursor chain (PDAA): N,N-dimethylacrylamide, 4-acryloyloxybenzophenone and acrylamide were mixed and heated and stirred at 333-338 K for 20-24 h. After the product was purified and dried, the precursor chain PDAA was obtained.

[0060] (2) Synthesis of single-chain nanoparticles: The precursor chain was dispersed in deionized water to obtain a dispersion with a concentration of 1-3 mg / mL. Then, it was irradiated with 365 nm ultraviolet light for 10-12 h to induce intramolecular crosslinking. After purification and drying, single-chain nanoparticles (SCNPs) were obtained and labeled as SDAA.

[0061] The synthetic route for single-chain nanoparticles is as follows:

[0062]

[0063] Among them, x+y+z=1, x=80.9%, y=6.2%, z=12.9%;

[0064] (3) Preparation of hydrogel: Acrylamide, crosslinking agent N,N'-methylenebisacrylamide, photoinitiator 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylacetophenone and SDAA are mixed and added to deionized water and stirred to form a homogeneous solution. Then, the solution is injected into a mold and cured by irradiation with a 365nm ultraviolet lamp for 3-6 hours to obtain a hydrogel based on the topological entanglement of single-chain nanoparticles (denoted as SDAA hydrogel).

[0065] The amount of crosslinking agent is 0.01 wt% of the amount of acrylamide; the amount of photoinitiator is 0.01 wt% of the amount of acrylamide; and the amount of SDAA is 1 wt% of the amount of acrylamide.

[0066] (4) Swelling equilibrium: Immerse in water baths at different temperatures (278K, 298K, 318K) until swelling equilibrium is reached.

[0067] Experimental Example 1

[0068] According to the scheme of Example 1, the amount of SNAA in step (3) was set to 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, and its mechanical properties were tested with polyacrylamide hydrogel as a reference. The results are shown in Table 1.

[0069] Table 1

[0070]

[0071] The results in Table 1 show that the SNAA synthesized according to the scheme in Example 1 is a NIPAM-based single-chain nanoparticle that exhibits topological change behavior of high-temperature collapse and low-temperature expansion in an aqueous environment. Figure 3 The temperature-dependent dynamic light scattering results of the single-chain nanoparticles SNAA prepared according to Example 1 are shown in the figure. The results indicate that the hydrodynamic radius of SNAA decreases as the temperature increases.

[0072] Compared to traditional copolymerization strategies that typically require a high proportion of functional components to achieve mechanical enhancement, hydrogel systems based on the topological entanglement of single-chain nanoparticles can produce significant enhancement effects with only trace amounts added. Figure 4 Stress-strain curves of hydrogels and polyacrylamide hydrogels with different contents of single-chain nanoparticles at room temperature are presented. When the content of single-chain nanoparticles (SNAA) is only 1 wt%, the tensile strength of the hydrogel reaches 777.8 kPa and the fracture strain reaches 950%, which is significantly better than that of pure polyacrylamide (PAAM) gel (408.3 kPa, 681%). Its toughness is more than twice that of PAAM gel, reaching 2477.2 kJ / m³ at room temperature. When the SNAA content increases to 3 wt%, the tensile strength and fracture strain increase to 1215.7 kPa and 1205%, respectively, which are equivalent to 2.95 times and 1.78 times that of the unmodified system, and the toughness increases sharply to 4451.4 kJ / m³, which is about 3.8 times that of the control group. These results indicate that this hydrogel synthesis strategy of topological entanglement of single-chain nanoparticles can achieve efficient network enhancement at low concentrations through the topological confinement effect, and the improvement is relatively balanced with the amount of 1-3 wt% SCNPs.

[0073] Figure 5 The image shows the performance of the 1 wt% SNAA hydrogel prepared in Example 1 at room temperature, indicating that the SNAA hydrogel has good optical transmittance and mechanical properties.

[0074] Figure 6 The temperature adaptability diagram of the SNAA hydrogel prepared according to Example 1 shows that the mechanical properties of the PAAM gel are temperature-sensitive, with a toughness of 1310.7 kJ / m³ at a low temperature of 278 K. In contrast, the 1 wt% SNAA gel still maintains a high toughness of 4488.0 kJ / m³, which is 3.4 times that of the PAAM gel under the same conditions. At a high temperature of 318 K, its tensile strength (>800 kPa) and fracture strain (>1050%) are still superior to the control group. Furthermore, the SNAA gel exhibits tunable progressive mechanical enhancement over a wide temperature range.

[0075] Figure 7The graph shows the water content of the SNAA hydrogels prepared according to Example 1, with water contents ranging from 85% to 90%. The sustained strengthening effect of the SNAA hydrogels under high water content conditions across a wide temperature range demonstrates the unique ability of topological entanglement of single-chain nanoparticles to impart mechanical strength and environmental tolerance to soft matter networks—a property that is difficult to achieve simultaneously in traditional hydrogel systems.

[0076] Figures 8-10 The images show the cyclic tensile and hysteresis diagrams of the 1 wt% SNAA hydrogel prepared in Example 1. Cyclic tensile testing demonstrates that the SCNP gel exhibits excellent mechanical resilience. Within a strain range of 200% to 800%, its hysteresis remains below 5%, exhibiting low energy dissipation and efficient elastic recovery. Even at a high strain of 800%, the gel maintains extremely low hysteresis. After 500 consecutive load-unload cycles, the material's mechanical behavior remains stable, with no significant performance degradation, confirming the excellent fatigue resistance of the SCNP gel. This low and stable hysteresis characteristic contrasts sharply with the limitations of traditional hydrogels, which suffer from severe energy dissipation restricting their cyclic deformation capabilities.

[0077] Furthermore, after multiple cycles at 800% strain (a value exceeding the fracture strain of PAAM gel), SCNP gel still exhibits excellent recovery ability and structural integrity. These results highlight the role of SCNPs as dynamically recoverable topological crosslinking points: they can dissipate energy through reversible conformational deformation while maintaining network continuity. This mechanism effectively resolves the common contradiction between material toughness and hysteresis, ultimately forming a hydrogel system that combines high strength, high fracture strain, and long-term mechanical reliability.

[0078] Experimental Example 2

[0079] According to the scheme of Example 2, the amount of SDAA in step (3) was set to 1 wt%, and the mechanical properties of polyacrylamide hydrogel were tested as a reference. The results are shown in Table 2. For easy comparison, the mechanical property data of polyacrylamide hydrogel are given repeatedly.

[0080] Table 2

[0081]

[0082] Figure 11 The image shows the size diagram of the SDAA single-chain nanoparticles prepared in Example 2. The comonomer is not thermosensitive and there are no significant size changes except for thermal fluctuations.

[0083] Based on the results of Experiment Example 2, 1 wt% was selected as the dosage of SDAA. Figure 12As shown in Table 2, at a low temperature of 278 K, the SDAA gel exhibits a tensile strength of 902.6 kPa, an elongation at break of 1178%, and a toughness of 3420.0 kJ / m³, which are approximately 2.22 times, 1.61 times, and 2.61 times that of the PAAM gel under the same conditions, respectively, demonstrating its significant reinforcing effect even at low temperatures. Notably, the modulus of the SDAA gel at low temperature (47.7 kPa) is significantly lower than that of the PAAM gel (88.4 kPa), indicating that its network achieves a simultaneous improvement in toughness and ductility while reducing rigidity.

[0084] As temperature increases, the mechanical properties of SDAA gel exhibit a certain temperature dependence. At 298 K, its strength, elongation at break, and toughness are 697.0 kPa, 1030%, and 2343.9 kJ / m³, respectively, still significantly better than PAAM gel. However, at 318 K, the difference in strength and toughness between SDAA gel and PAAM gel narrows, reflecting a slight decrease in the reinforcing ability of its non-thermosensitive structure at high temperatures, but it still maintains good overall mechanical properties.

[0085] The above results demonstrate that even without temperature sensitivity, SDAA, acting as a topological crosslinking point, can effectively enhance the mechanical properties of hydrogels, especially at low temperatures. Combining these experimental results with the performance of SNAA in Example 1 further confirms that the enhancement effect achieved by single-chain nanoparticles through topological entanglement is universal, and its specific response behavior can be flexibly controlled according to its chemical structure (e.g., whether or not a temperature-sensitive unit is introduced), thereby adapting to the environmental adaptability requirements of materials in different application scenarios.

[0086] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for preparing a hydrogel based on topological entanglement of single-stranded nanoparticles, characterized by, Includes the following steps: (1) Synthesis of random copolymer precursor chains by reversible addition-fragmentation chain transfer polymerization: The precursor chain monomer, 4-acryloyloxybenzophenone and acrylamide are mixed and heated, stirred and reacted, and the product is reprecipitated with n-pentane, separated and dried under vacuum to obtain the precursor chain; the precursor chain monomer is N-isopropylacrylamide or N,N-dimethylacrylamide; the molar ratio of the precursor chain monomer, 4-acryloyloxybenzophenone and acrylamide is 15:1:4; the heating and stirring reaction temperature is 333-338K, the reaction time is 20-24h, and the vacuum drying temperature is 313-323K; (2) Synthesis of single-chain nanoparticles: The precursor chain was dispersed in deionized water to obtain a dispersion, and then irradiated with ultraviolet light to induce intramolecular crosslinking. After purification and drying, single-chain nanoparticles were obtained, denoted as SCNPs. The ultraviolet light irradiation wavelength was 365 nm and the irradiation time was 10-12 h. (3) Preparation of hydrogel: Acrylamide, crosslinking agent, photoinitiator and SCNPs are mixed and added to deionized water and stirred to form a homogeneous solution, which is then poured into a mold and cured by UV irradiation; (4) Swelling equilibrium: The solidified hydrogel is immersed in a water bath until swelling equilibrium is reached to obtain a hydrogel based on the topological entanglement of single-chain nanoparticles.

2. The method for preparing a hydrogel based on the topological entanglement of single-chain nanoparticles according to claim 1, characterized in that, The concentration of the precursor chain in the dispersion in step (2) is 1-3 mg / mL.

3. The method for preparing a hydrogel based on the topological entanglement of single-chain nanoparticles according to claim 1, characterized in that, The crosslinking agent in step (3) is N,N'-methylenebisacrylamide; the photoinitiator is 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylacetophenone.

4. The method for preparing a hydrogel based on the topological entanglement of single-chain nanoparticles according to claim 1 or 3, characterized in that, The amount of crosslinking agent used in step (3) is 0.01-1 wt% of the amount of acrylamide; the amount of photoinitiator used is 0.008-0.012 wt% of the amount of acrylamide; and the amount of SCNPs used is 1-5 wt% of the amount of acrylamide.

5. The method for preparing a hydrogel based on the topological entanglement of single-chain nanoparticles according to claim 1, characterized in that, The ultraviolet lamp irradiation wavelength in step (3) is 365nm, and the irradiation time is 3-6h.

6. The method for preparing a hydrogel based on the topological entanglement of single-chain nanoparticles according to claim 1, characterized in that, The water bath temperature in step (4) is 278K-318K and the water bath time is 24-30h.

7. A hydrogel based on the topological entanglement of single-chain nanoparticles, characterized in that, It is prepared by the method described in any one of claims 1-6.

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