Polyrotaxane sliding ring double-network hydrogel based on photopolymerization end capping as well as preparation method and application of polyrotaxane sliding ring double-network hydrogel
Polyrotaxane sliding ring dual-network hydrogels were prepared by photopolymerization end-capping, which solved the problem of insufficient dynamic response performance of existing hydrogels, and achieved rapid response to environmental stimuli and rich mechanical properties, with self-healing and antibacterial capabilities.
Patent Information
- Application Number
- CN202511225492.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-29
- Publication Date
- 2025-11-14
AI Technical Summary
Existing sliding ring hydrogels are insufficient in terms of dynamic response performance, making it difficult to meet the needs of the smart materials field for rapid response to environmental stimuli such as temperature, pH value, and light.
Polyrotaxane sliding ring double network hydrogels were prepared by photopolymerization end-capping. A macromolecular crosslinking agent was formed by modifying the end positions of the triblock copolymer poly(ethylene glycol)-poly(propylene glycol)-poly(ethylene glycol), and then mixed with aldehyde-β-cyclodextrin and monomers. After adding gelatin, a photoreaction was carried out to form dynamic covalent bonds and a double network structure.
It improves the dynamic responsiveness of hydrogels, and possesses excellent mechanical properties, self-healing ability and antibacterial properties, enabling them to respond quickly to environmental stimuli in flexible smart materials.
Smart Images
Figure CN120944139A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of hydrogel preparation technology, specifically to a photopolymer-terminated polyrotaxane sliding ring dual-network hydrogel, its preparation method, and its application. Background Technology
[0002] Hydrogels are a class of flexible polymer materials formed by cross-linking of polymers containing hydrophilic groups. Due to their excellent and unique hydrophilic properties, such as swelling without dissolving, these materials have been widely used in various fields including biomedical materials, sensors, batteries, and flexible smart materials.
[0003] Traditional hydrogels are mainly prepared by chemically crosslinking hydrophilic polymers, and they possess excellent mechanical properties, making them suitable for fields with high mechanical performance requirements. However, with the development of science and technology, hydrogels with only excellent mechanical properties but limited functionality are no longer sufficient to meet the needs of more complex applications; especially with the advent of the smart era, the demand for flexible smart materials is increasing significantly.
[0004] Currently, a novel type of hydrogel based on supramolecular polymer networks, known as sliding ring hydrogel or polyrotaxane hydrogel due to its sliding ring or polyrotaxane structure, has attracted widespread attention in recent years. In the network structure of this hydrogel, topological cross-linking is achieved through ring structures, thereby forming cross-linked polymer chains. The core difference between traditional hydrogels and sliding ring hydrogels lies in the cross-linking mechanism: traditional hydrogels use chemical cross-linking, and their cross-linking points are fixed structures. Under external forces, uneven stress distribution easily occurs within the hydrogel network, which may lead to network structure failure. In contrast, the characteristic of sliding ring hydrogels is that their ring structures act as movable cross-linking points. When subjected to external forces, these ring structures can slide along the polymer chains, similar to the movement of a pulley. This pulley effect enables the stress to be evenly distributed throughout the chain segments and the entire network, thus endowing sliding ring hydrogels with excellent mechanical properties, including extreme softness, low initial modulus, and enhanced ductility.
[0005] However, existing sliding ring hydrogels still have certain shortcomings. Their dynamic response performance needs to be improved, making it difficult to meet the needs of the field of smart materials for rapid response to environmental stimuli such as temperature, pH value, and light. Summary of the Invention
[0006] To address the shortcomings of existing technologies, this invention provides a photopolymer-terminated polyrotaxane sliding ring dual-network hydrogel, its preparation method, and its application. The photopolymer-terminated polyrotaxane sliding ring dual-network hydrogel prepared by this invention improves dynamic responsiveness and can meet the needs of rapid response to environmental stimuli in the field of smart materials.
[0007] The technical solution adopted by this invention to solve the above-mentioned technical problems is as follows: a method for preparing a polyrotaxane sliding ring dual-network hydrogel based on photopolymerization end-capping, comprising the following steps:
[0008] S1. Modify the end positions of the triblock copolymer poly(ethylene glycol)-poly(propylene glycol)-poly(ethylene glycol) to obtain a macromolecular crosslinking agent;
[0009] S2. Dissolve the macromolecular crosslinking agent, aldehyde-β-cyclodextrin and monomer in deionized water, then add the photoinitiator to obtain a mixture;
[0010] S3. After mixing the mixture and the gelatin aqueous solution, let it stand to defoam, and then carry out the photo-irradiation reaction to obtain the polyrotaxane sliding ring dual network hydrogel based on photopolymerization end capping.
[0011] As a further optimization of the method for preparing a photopolymer-terminated polyrotaxane sliding ring dual-network hydrogel: S1 specifically includes:
[0012] Methacrylic anhydride and the terminal hydroxyl groups of the triblock copolymer poly(ethylene glycol)-poly(propylene glycol)-poly(ethylene glycol) are reacted to generate a macromolecular crosslinking agent, methacrylate.
[0013] As a further optimization of the preparation method of a photopolymer-terminated polyrotaxane sliding ring dual-network hydrogel, the photoreaction conditions are: irradiation under a 405nm ultraviolet lamp for 20 minutes.
[0014] As a further optimization of the preparation method of a photopolymer-terminated polyrotaxane sliding ring dual-network hydrogel, the photoinitiator is lithium phenyl (2,4,6-trimethylbenzoyl) phosphate.
[0015] As a further optimization of the preparation method of a photopolymer-terminated polyrotaxane sliding ring dual-network hydrogel: the aldehyde-β-cyclodextrin is obtained by oxidizing the β-cyclodextrin hydroxyl group with sodium periodate.
[0016] As a further optimization of the preparation method of a photopolymer-terminated polyrotaxane sliding ring dual-network hydrogel, the monomer is N-vinylpyrrolidone, 4-acryloylmorpholine, or methacryloyloxyethyltrimethylammonium chloride.
[0017] As a further optimization of the preparation method of a photopolymer-terminated polyrotaxane sliding ring dual-network hydrogel, the monomer is methacryloyloxyethyltrimethylammonium chloride.
[0018] As a further optimization of the preparation method of a photopolymer-terminated polyrotaxane sliding ring dual-network hydrogel, the molar ratio of the methacryloyloxyethyltrimethylammonium chloride and the macromolecular crosslinking agent is 75:1.
[0019] The technical solution adopted by the present invention to solve the above-mentioned technical problems is: a polyrotaxane sliding ring dual-network hydrogel based on photopolymerization end capping, which is prepared by the above method.
[0020] The technical solution adopted by the present invention to solve the above-mentioned technical problems is: the application of a photopolymer-terminated polyrotaxane sliding ring dual-network hydrogel in the preparation of flexible smart materials.
[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0022] 1) In this invention, methacrylic anhydride and the terminal hydroxyl groups of the triblock copolymer poly(ethylene glycol)-poly(propylene glycol)-poly(ethylene glycol) react to generate methacrylate. The methacrylate reacts with cyclodextrin host and guest to form quasi-rotaxane. In addition, thanks to the modification of the terminal positions of the triblock copolymer poly(ethylene glycol)-poly(propylene glycol)-poly(ethylene glycol), it can be further polymerized with monomer molecules on free radicals. During polymerization, the quasi-rotaxane mechanism is end-capped to form a rotaxane structure, forming a polyrotaxane sliding ring structure, which greatly enriches the potential mechanical properties.
[0023] 2) This invention uses aldehyde-β-cyclodextrin instead of conventional β-cyclodextrin. In addition to forming a rotaxane structure, the aldehyde group on the aldehyde-β-cyclodextrin provides more reaction sites. After adding gelatin, the gelatin amino group reacts with the aldehyde group to form a Schiff base reaction to form a dynamic covalent bond, forming a double network hydrogel, which also enriches the responsiveness.
[0024] 3) This invention uses quaternary ammonium salt monomers, which can potentially improve the antibacterial properties of the hydrogel itself; at the same time, the raw materials of this hydrogel are simple and low in cost, and the novel combination of polyrotaxane sliding ring structure and dynamic covalent bond double network provides a good idea for the preparation of double network hydrogels, which also have broad application prospects. Attached Figure Description
[0025] Figure 1 These are SEM images of the OCD / DN-Gel prepared in Example 1 of the present invention, the DMC / SN-Gel prepared in Comparative Example 1, and the OCD / SN-Gel prepared in Comparative Example 2 at different magnifications.
[0026] Figure 2 Fourier transform infrared spectra of the reagents used in Example 1 of this invention, the reagents prepared, the hydrogels prepared, and the hydrogels prepared in Comparative Examples 1 and 2.
[0027] Figure 3 The stress-strain diagram (a) and compressive modulus (b) of the hydrogels prepared in Example 1, Comparative Example 1 and Comparative Example 2 of the present invention are shown.
[0028] Figure 4 The swelling degree, equilibrium swelling degree, and swelling cycle curves of the OCD / DN-Gel prepared in Example 1 were measured at different pH values.
[0029] Figure 5 The swelling degree, equilibrium swelling degree, and swelling cycle curves of the OCD / DN-Gel prepared in Example 1 were measured at different temperatures.
[0030] Figure 6 This describes the self-healing process of the OCD / DN-Gel prepared in Example 1;
[0031] Figure 7 The antibacterial properties of the OCD / DN-Gel prepared in Example 1 are shown.
[0032] Figure 8 NMR characterization of the quasi-rotaxane structure. Detailed Implementation
[0033] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. Parts not described or disclosed in detail in the following embodiments should be understood as prior art known or should be known by those skilled in the art. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in this technical field; unless otherwise specified, the reagents and materials used in the present invention are all commercially available.
[0034] A method for preparing a photopolymer-terminated polyrotaxane sliding ring dual-network hydrogel includes the following steps:
[0035] S1. Modifying the ends of the triblock copolymer poly(ethylene glycol)-poly(propylene glycol)-poly(ethylene glycol) to obtain a macromolecular crosslinking agent; S1 specifically involves:
[0036] Methacrylic anhydride and the terminal hydroxyl groups of the triblock copolymer poly(ethylene glycol)-poly(propylene glycol)-poly(ethylene glycol) are reacted to generate a macromolecular crosslinking agent, methacrylate, which is then given free radical polymerization sites.
[0037] In this study, the triblock copolymer poly(ethylene glycol)-poly(propylene glycol)-poly(ethylene glycol) is represented by PEO-PPO-PEO, and the methacrylate is represented by MPEO-PPO-MPEO. The modification route for obtaining MPEO-PPO-MPEO by end-position modification of PEO-PPO-PEO is as follows:
[0038]
[0039] Where n represents a PEO repeating unit and m represents a PPO repeating unit.
[0040] S2. Dissolve the macromolecular crosslinking agent, aldehyde-β-cyclodextrin, and monomer in deionized water, then add the photoinitiator to obtain a mixture; aldehyde-β-cyclodextrin is represented by OX-β-CD. The monomer is N-vinylpyrrolidone, 4-acryloylmorpholine, or methacryloyloxyethyltrimethylammonium chloride, preferably methacryloyloxyethyltrimethylammonium chloride, represented by DMC. The photoinitiator is lithium phenyl (2,4,6-trimethylbenzoyl) phosphate, represented by LAP.
[0041] This invention utilizes aldehyde-β-cyclodextrin, which, in addition to forming a rotaxane structure, provides a wider range of reaction sites due to the aldehyde group. The addition of gelatin results in a Schiff base reaction between the gelatin amino groups and the aldehyde group, forming dynamic covalent bonds and creating a double-network hydrogel, further enhancing its responsiveness. The use of quaternary ammonium salt monomers potentially improves the antibacterial properties of the hydrogel itself. Furthermore, the hydrogel uses simple and low-cost raw materials, and the novel combination of the polyrotaxane sliding ring structure and the dynamic covalent double network provides a promising approach for the preparation of double-network hydrogels.
[0042] The preparation method of aldehyde-β-cyclodextrin is as follows:
[0043] Aldehyde-β-cyclodextrin is obtained by oxidizing the hydroxyl group of β-cyclodextrin with sodium periodate, and aldehyde-β-cyclodextrin provides Schiff base reaction sites.
[0044] Methacrylate and aldehyde-β-cyclodextrin form a quasi-polyrotaxane crosslinking agent through host-guest interactions. This invention benefits from the modification of the end positions of the triblock copolymer poly(ethylene glycol)-poly(propylene glycol)-poly(ethylene glycol), which allows for further radical polymerization with monomer molecules. During polymerization, the quasi-rotaxane mechanism is simultaneously capped to form a rotaxane structure, resulting in a polyrotaxane sliding ring structure, significantly enriching its potential mechanical properties. The quasi-rotaxane structure is as follows: Figure 8 As shown.
[0045] S3. After mixing the mixture and gelatin aqueous solution, allow it to stand to defoam, and then conduct a photo-irradiation reaction to obtain the photopolymer-terminated polyrotaxane sliding ring dual-network hydrogel. Specifically, S3 involves: thoroughly mixing the mixture and gelatin aqueous solution using ultrasonic vibration, allowing it to stand to eliminate bubbles; pouring the mixed mixture and gelatin aqueous solution into a mold and allowing it to stand for a certain time; then irradiating it under a 405nm ultraviolet lamp for 20 minutes to initiate cross-linking and gel formation, thus obtaining the photopolymer-terminated polyrotaxane sliding ring dual-network hydrogel. The photopolymer-terminated polyrotaxane sliding ring dual-network hydrogel is denoted as OCD / DN-Gel. The method for preparing the photopolymer-terminated polyrotaxane sliding ring dual-network hydrogel uses simple and inexpensive raw materials, operates under mild reaction conditions, and exhibits good biocompatibility.
[0046] The molar ratio of methacryloyloxyethyltrimethylammonium chloride to the macromolecular crosslinking agent is 75:1; preferably, the molar ratio of repeating unit to cyclodextrin is PO:CD = 6:1. Based on this, the mass concentration of gelatin can be adjusted as needed.
[0047] Example 1
[0048] A method for preparing a photopolymer-terminated polyrotaxane sliding ring dual-network hydrogel includes the following steps:
[0049] 1) Synthesis of macromolecular crosslinking agents:
[0050] 20 g (1.667 mmol) of the triblock copolymer PEO-PPO-PEO was completely dissolved in a 250 mL round-bottom flask containing 150 mL of 1,4-dioxane. Then, 2.57 g (16.67 mmol) of methacrylic anhydride was added, and the mixture was thoroughly mixed to obtain a clear solution. The solution was then reacted at 85 °C under an argon atmosphere for 10 h. After the reaction, most of the solvent was removed by rotary evaporation to increase the polymer concentration, and then the polymer was precipitated with 200 mL of petroleum ether. This process was repeated three times. The polymer was then filtered and dried under vacuum at 25 °C to obtain 18.7406 g of a white solid, with a yield of approximately 83.2%. The product was named MPEO-PPO-MPEO.
[0051] 2) Synthesis of aldehyde-β-cyclodextrin:
[0052] According to the literature method, sodium periodate was used as an oxidant to prepare cyclodextrin with an aldehyde group: 8.1 g and 7.137 mmol of β-CD were dissolved in 100 mL of deionized water, and then 10.9 g and 50.96 mmol of sodium periodate were added. After mixing, a clear solution was obtained. The reaction flask was completely wrapped with aluminum foil and placed in a dark environment at 40 °C with magnetic stirring for 4 h. After the reaction was completed, the aluminum foil was removed, 3.1 g of ethylene glycol was added, and the reaction was continued for 0.5 h. Then, excess anhydrous calcium chloride was added, with a molar ratio of calcium ions to sodium periodate ≥ 1:2. The precipitate was removed by filtration. The obtained filtrate was freeze-dried to obtain 7.3712 g of white powder, with a yield of 91%. The product was named OX-β-CD.
[0053] 3) Preparation of polyrotaxane sliding ring dual-network hydrogels based on photopolymerization-terminated end caps:
[0054] 0.4 g of MPEO-PPO-MPEO, 0.3875 g of OX-β-CD, and 1.0281 g of DMC were dissolved in 5.016 mL of deionized water to prepare a mixed solution. Separately, 1.7070 g of gelatin was dissolved in 1.5 mL of deionized water to prepare a gelatin aqueous solution. The two solutions were thoroughly mixed by ultrasonic vibration. Then, 420 μL of LAP was added to the system, stirred until homogeneous, and allowed to stand to eliminate air bubbles. The mixed solution was then poured into a mold, allowed to stand for a specific time, and then subjected to photo-initiated crosslinking under a 405 nm UV lamp. This resulted in a photopolymer-terminated polyrotaxane sliding ring dual-network hydrogel, denoted as OCD / DN-Gel.
[0055] This invention first involves an end-position modification reaction of a triblock copolymer, poly(ethylene glycol)-poly(propylene glycol)-poly(ethylene glycol), with methacrylic anhydride, followed by host-guest interaction between the copolymer and aldehyde-β-cyclodextrin to form a quasi-polyrotaxane. Subsequently, methacryloyloxyethyltrimethylammonium chloride, gelatin, and a photoinitiator are added, and photo-induced free radical polymerization of the quasi-polyrotaxane is used for end-capping, forming a polyrotaxane slip-ring monolayer hydrogel. Finally, further crosslinking is achieved through the Schiff base reaction between the amino groups in the gelatin and the aldehyde groups in the cyclodextrin, yielding OCD / DN-Gel. This hydrogel exhibits uniform pore size, intelligently controllable mechanical properties, and excellent sensitivity to pH and temperature changes. It also possesses superior self-healing ability and antibacterial activity, demonstrating promising application potential in the field of flexible smart materials.
[0056] Comparative Example 1
[0057] The only difference between Comparative Example 1 and Example 1 is that no gelatin aqueous solution was added in Comparative Example 1. Otherwise, they are the same as in Example 1, and a single-network hydrogel I was prepared, which is represented by DMC / SN-Gel.
[0058] Comparative Example 2
[0059] The only difference between Comparative Example 2 and Example 1 is that Comparative Example 2 did not include the monomer molecule DMC and the photoinitiator LAP, and therefore did not require light illumination. Otherwise, it was the same as Example 1, and a single-network hydrogel II was prepared, denoted as OCD / SN-Gel.
[0060] A photopolymer-terminated polyrotaxane sliding ring dual-network hydrogel was prepared by a method for preparing photopolymer-terminated polyrotaxane sliding ring dual-network hydrogels. The unique sliding ring structure and dynamic covalent bonds of the photopolymer-terminated polyrotaxane sliding ring dual-network hydrogel endow it with rich mechanical properties and responsiveness; furthermore, the photopolymer-terminated polyrotaxane sliding ring dual-network hydrogel exhibits good self-healing ability and antibacterial properties.
[0061] Performance testing
[0062] 1) SEM characterization
[0063] SEM images of the OCD / DN-Gel prepared in Example 1, the DMC / SN-Gel prepared in Comparative Example 1, and the OCD / SN-Gel prepared in Comparative Example 2 after lyophilization are shown below. Figure 1 As shown; Figure 1 Parts (a) and (d) are DMC / SN-Gel prepared in Comparative Example 1, (b) and (e) are OCD / SN-Gel prepared in Comparative Example 2, and (c) and (f) are OCD / SN-Gel prepared in Example 1.
[0064] Depend on Figure 1 It can be seen that the porous structures of DMC / SN-Gel and OCD / SN-Gel have their own characteristics. The pores of DMC / SN-Gel are nearly circular, similar in size, and uniformly distributed, but some pores are surface structures, which are not conducive to water molecule storage. OCD / SN-Gel, formed by Schiff base bonds, has a porous structure resembling stacked paper sheets, with thicker outer walls and thinner inner walls, and deeper pores, which is beneficial for drug and water molecule storage. In contrast, OCD / SN-Gel exhibits a porous structure with deeper pores and uniform wall thickness. This is due to the formation of a dual network, which combines the pore size characteristics of both single-network hydrogels I and II, namely DMC / SN-Gel and OCD / SN-Gel.
[0065] 2) Fourier transform infrared spectroscopy test
[0066] The reagents used in Example 1, the prepared reagents, the prepared hydrogel, and the Fourier transform infrared spectra of the hydrogels prepared in Comparative Examples 1 and 2 are as follows: Figure 2 As shown. Among them Figure 2 In the middle (a), there is a comparison diagram of (Ⅰ) PEO-PPO-PEO, (Ⅱ) MPEO-PPO-MPEO and (Ⅲ) DMC / SN-Gel. Figure 2 In the middle (b), there is a comparison diagram of (Ⅰ)β-CD and (Ⅱ)OX-β-CD. Figure 2 In the middle (c), there is a comparison diagram of (Ⅰ) gelatin, (Ⅱ) OX-β-CD and (Ⅲ) OCD / SN-Gel. Figure 2 The middle (d) is a comparison diagram of (Ⅰ) DMC / SN-Gel, (Ⅱ) OCD / SN-Gel and (Ⅲ) OCD / DN-Gel.
[0067] Figure 2 In (a), 1455cm -1 The absorption peak at 1406 cm⁻¹ corresponds to the CH bending vibration (methyl and methylene); -1 The absorption peak at 1238 cm⁻¹ is attributed to the CN stretching vibration of DMC. -1 1053cm -1and 1101cm -1 The absorption peak at 910-830 cm⁻¹ corresponds to the CC framework vibration and the characteristic vibration of COC; -1 The absorption peak in the region originates from the CH plane stretching vibration. (1715 cm⁻¹) -1 The peak at 1635 cm⁻¹ represents the characteristic C=O vibration of methacrylic anhydride (MAC). -1 The characteristic absorption peak at this location corresponds to the C=C stretching vibration, which is characteristic of the MPEO-PPO-MPEO structure. When MPEO-PPO-MPEO and DMC are photocrosslinked to form DMC / SN-Gel, the double bond characteristic peak basically disappears, indicating that the photocrosslinking reaction has occurred and a hydrogel has been formed.
[0068] Figure 2 In (b), β-CD is at 3302 cm⁻¹. -1 The peak at 2925 cm⁻¹ exhibits the characteristic peak of OH stretching vibration. -1 The peak at 1636 cm⁻¹ represents the CH stretching vibration. -1 The peak at 1151 cm⁻¹ represents the HOH bending vibration peak. -1 and 1037cm -1 The absorption peaks at 1731 cm⁻¹ are attributed to the COC stretching vibration and CO stretching vibration in the glycoside structure, respectively. In the OX-β-CD spectrum, the peak at 1731 cm⁻¹ is... -1 A new vibrational band appears at a certain point, corresponding to the stretching vibration of its aldehyde group (-CHO); however, the signal of this aldehyde group peak is weak, possibly because most aldehyde groups exist in the form of hemiacetals, or due to limitations in FTIR detection sensitivity, which fails to identify the masked aldehyde functional group. β-CD has a cyclic structure, with its glucose units linked by 1-4 glycosidic COC bonds. This structure can be formed by a 1151 cm⁻¹ -1 The COC peak at 1037 cm⁻¹ and 1037 cm⁻¹ -1 The CO peak at the location confirms this. Furthermore, the intensity of the COC vibrational peak in OX-β-CD is significantly reduced but not completely disappears, indicating that the cavity structure of oxidized β-CD is not completely destroyed.
[0069] Figure 2 (c) , 3345cm -1 The absorption peak at 3302 cm⁻¹ is related to the NH stretching vibration of gelatin; -1 The peak at 3212 cm⁻¹ is attributed to the characteristic peak of the OH stretching vibration of β-CD. Gelatin at 3212 cm⁻¹... -1 The disappearance of the characteristic amino peak at 2925 cm⁻¹ confirms that the amino group undergoes a Schiff base reaction with the aldehyde group to form an OCD / SN-Gel
[198] . -1 The infrared absorption peak at 1406 cm⁻¹ is related to the CH stretching vibration; -1 1250cm -1 and 1071cm -1The peaks at the specified locations are attributed to the symmetric stretching vibration of the carboxyl group in the gelatin side chain, the characteristic vibration of the amide band, and the CN stretching vibration of the primary amine, respectively.
[0070] Figure 2 (d) Comparing the spectra of OCD / DN-Gel, DMC / SN-Gel and OCD / SN-Gel, it can be seen that OCD / DN-Gel contains all the characteristic absorption peaks of DMC / SN-Gel and OCD / SN-Gel, and the absorption peak of OCD / DN-Gel is significantly enhanced, thus proving that a double network hydrogel is formed.
[0071] 3) Mechanical property difference test
[0072] To compare the differences in mechanical properties between single-network and dual-network hydrogels, the compressive properties of DMC / SN-Gel (Comparative Example 1), OCD / SN-Gel (Comparative Example 2), and OCD / DN-Gel (Example 1) were investigated. The results are as follows: Figure 3 As shown.
[0073] like Figure 3 As shown, the compressive modulus of the dual-network hydrogel is significantly better than that of the single-network hydrogel. Furthermore, DMC / SN-Gel, formed solely by photocrosslinking, exhibited fragmentation during compression. The addition of the highly plastic OCD / SN-Gel compensated for the fragility of the DMC / SN-Gel gel network.
[0074] 4) pH sensitivity test
[0075] The swelling degree and equilibrium swelling degree of Example 1 were tested at different pH values, and the results are as follows: Figure 4 As shown, Figure 4 (a) Swelling degree of OCD / DN-Gel prepared in Example 1 at different pH values Figure 4 (b) represents the equilibrium swelling degree of the OCD / DN-Gel prepared in Example 1 at different pH values. Figure 4 (c) shows the swelling cycle curves of the OCD / DN-Gel prepared in Example 1 at pH=6 and pH=10.
[0076] from Figure 4It is evident that the swelling degree of OCD / DN-Gel exhibits a trend of first slowly increasing and then gradually decreasing with rising pH, reaching a peak of approximately 1593% at pH=6. This phenomenon can be explained by a molecular mechanism: as pH increases, the -COOH groups in gelatin molecules gradually dissociate into -COO-, leading to a weakening of hydrogen bonding forces between molecular chains. Consequently, the hydrogel network expands, increasing the internal pore structure and thus increasing the swelling degree. Furthermore, as a dynamic covalent bond, the Schiff base bond's reaction equilibrium is regulated by pH. When the environment changes from weakly acidic to alkaline, Schiff base crosslinking points are rebuilt, increasing the crosslinking density and consequently decreasing the swelling degree.
[0077] During repeated immersion in buffer solutions at pH 6 and pH 10, the swelling degree of OCD / DN-Gel showed a slight decrease in the alkaline environment, which is consistent with the above analysis. After 5 cycles, OCD / DN-Gel maintained good pH sensitivity, indicating its good cycling performance and stability.
[0078] 5) Temperature sensitivity test
[0079] The swelling degree and equilibrium swelling degree of Example 1 were tested at different temperatures, and the results are as follows: Figure 5 As shown, Figure 5 (a) The swelling degree of the OCD / DN-Gel prepared in Example 1 at different temperatures. Figure 5 (b) represents the equilibrium swelling degree of the OCD / DN-Gel prepared in Example 1 at different temperatures. Figure 5 (c) shows the swelling cycle curves of the hydrogel prepared in Example 1 at 20°C and 60°C.
[0080] like Figure 5 As shown, the swelling degree of OCD / DN-Gel increases with increasing temperature. Specifically, as the temperature increases, the thermal motion of the polymer molecular chains intensifies, causing the internal network structure of the hydrogel to become looser, providing more space for water molecules to penetrate, thus increasing the swelling degree. Conversely, as the temperature decreases, the movement rate of the gel network chain segments slows down, hindering the diffusion of water molecules into the gel interior, resulting in a decrease in the swelling degree.
[0081] The OCD / DN-Gel molecular structure contains a large number of hydrophobic and hydrophilic groups. Temperature changes significantly affect the hydrophobic and hydrophilic interactions of these groups and the interactions between macromolecular chains, thereby altering the swelling behavior of the OCD / DN-Gel. To further verify its performance stability, the hydrogel was subjected to five cycles in buffer solutions at 20℃ and 60℃. The results showed that it maintained good temperature sensitivity, indicating that the OCD / DN-Gel has excellent cycling stability.
[0082] 6) Self-healing performance test
[0083] The self-healing properties of Example 1 were investigated. For ease of observation, the gel was stained during preparation, such as... Figure 6 As shown.
[0084] Example 1 describes the preparation of OCD / DN-Gel via photocrosslinking and Schiff base reaction. In this structure, the OX-β-CD and the long chains of the crosslinking agent MPEO-PPO-MPEO can assemble into a "pulley" structure through host-guest interactions. This unique sliding structure endows the hydrogel with a flexible network framework and excellent compressibility.
[0085] The self-healing OCD / DN-Gel can complete the repair after 12 hours of undisturbed self-healing. Horizontal and vertical tensile and folding tests were performed on the repaired OCD / DN-Gel, and the results showed that its cut cross-section had recovered to its original state, confirming that the OCD / DN-Gel possesses excellent self-healing properties.
[0086] 7) Antibacterial performance test
[0087] The antibacterial properties of the OCD / DN-Gel from Example 1 were investigated. The results are as follows: Figure 7 As shown.
[0088] Optical microscope images of the double-network hydrogel OCD / DN-Gel samples prepared in Example 1 after culturing in Staphylococcus aureus and Escherichia coli cultures for 24 hours. The results showed that the average diameter of the inhibition zone on the agar plate cultured with Staphylococcus aureus was 13.5 ± 0.5 mm; and the average diameter of the inhibition zone on the agar plate cultured with Escherichia coli was 7 ± 1 mm. This indicates that the prepared hydrogel has certain antibacterial activity, and its inhibitory effect on Staphylococcus aureus is superior.
[0089] An application of a photopolymer-terminated polyrotaxane sliding ring dual-network hydrogel, such as the application of the above-mentioned hydrogel in the preparation of flexible smart materials.
[0090] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A method for preparing a polyrotaxane sliding ring dual-network hydrogel based on photopolymerization-terminated hydrogel, characterized in that, Includes the following steps: S1. Modify the end positions of the triblock copolymer poly(ethylene glycol)-poly(propylene glycol)-poly(ethylene glycol) to obtain a macromolecular crosslinking agent; S2. Dissolve the macromolecular crosslinking agent, aldehyde-β-cyclodextrin and monomer in deionized water, then add the photoinitiator to obtain a mixture; S3. After mixing the mixture and the gelatin aqueous solution, let it stand to defoam, and then carry out the photo-irradiation reaction to obtain the polyrotaxane sliding ring dual network hydrogel based on photopolymerization end capping.
2. The method for preparing a photopolymer-terminated polyrotaxane sliding ring dual-network hydrogel as described in claim 1, characterized in that, S1 specifically refers to: Methacrylic anhydride and the terminal hydroxyl groups of the triblock copolymer poly(ethylene glycol)-poly(propylene glycol)-poly(ethylene glycol) are reacted to generate a macromolecular crosslinking agent, methacrylate.
3. The method for preparing a photopolymer-terminated polyrotaxane sliding ring dual-network hydrogel as described in claim 1, characterized in that, The photoreaction conditions were 20 minutes of illumination under a 405nm ultraviolet lamp.
4. The method for preparing a photopolymer-terminated polyrotaxane sliding ring dual-network hydrogel as described in claim 1, characterized in that, The photoinitiator is lithium phenyl (2,4,6-trimethylbenzoyl) phosphate.
5. The method for preparing a photopolymer-terminated polyrotaxane sliding ring dual-network hydrogel as described in claim 1, characterized in that, The aldehyde-β-cyclodextrin is obtained by oxidizing the β-cyclodextrin hydroxyl group with sodium periodate.
6. The method for preparing a photopolymer-terminated polyrotaxane sliding ring dual-network hydrogel as described in claim 1, characterized in that, The monomer is N-vinylpyrrolidone, 4-acryloylmorpholine, or methacryloyloxyethyltrimethylammonium chloride.
7. The method for preparing a photopolymer-terminated polyrotaxane sliding ring dual-network hydrogel as described in claim 6, characterized in that, The monomer is methacryloyloxyethyltrimethylammonium chloride.
8. The method for preparing a photopolymer-terminated polyrotaxane sliding ring dual-network hydrogel as described in claim 7, characterized in that, The molar ratio of the methacryloyloxyethyltrimethylammonium chloride to the macromolecular crosslinking agent is 75:
1.
9. A polyrotaxane sliding ring dual-network hydrogel based on photopolymerization-terminated end-capping, characterized in that, Prepared by the method described in any one of claims 1-8.
10. The application of the photopolymer-terminated polyrotaxane sliding ring dual-network hydrogel as described in claim 9 in the preparation of flexible smart materials.