Temperature control hydrogel and preparation method thereof
By preparing polyglutamic acid-methacrylate copolymer and chitosan-modified fullerene, a high-density network structure was formed, which solved the problems of insufficient mechanical strength and poor biocompatibility of temperature-controlled hydrogels, and achieved high swelling ratio and excellent mechanical properties.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANDONG YINGLAIWANG AGRI TECH CO LTD
- Filing Date
- 2026-01-27
- Publication Date
- 2026-05-12
AI Technical Summary
Existing temperature-controlled hydrogels suffer from insufficient mechanical strength, low loading capacity, and poor biocompatibility. In particular, the weak aggregation and binding force of carbon nanotubes lead to a decrease in the mechanical strength of the hydrogel.
A high-density network structure was formed by preparing polyglutamic acid-methacrylate copolymer, composite chitosan, and chitosan-modified fullerene. The binding force was enhanced by amide bonds and hydrogen bonds, which improved dispersibility and mechanical strength. The stability and hydrophilicity of the material were ensured by controlling the reaction conditions through ultrasonic oscillation and dropwise addition.
It improves the mechanical strength and biocompatibility of temperature-controlled hydrogels, enhances the dispersibility of fullerenes, improves the stability of the load and the swelling rate of the hydrogel, and exhibits excellent mechanical and temperature-controlled properties.
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Abstract
Description
Technical Field
[0001] This invention provides a temperature-controlled hydrogel and its preparation method, belonging to the technical field of polymer compound compositions. Background Technology
[0002] Hydrogels are soft materials with a three-dimensional network structure built by covalent bonds, ionic cross-linking, coordination complexation and molecular aggregation. They are solid in appearance, flexible in texture, and have high water absorption and water insolubility. The water content can exceed 90%. As a functionalized branch, thermosensitive hydrogels are composed of hydrophilic polymer chains that cross-link to form a network framework and encapsulate a large number of water molecules. Their characteristic is that when the ambient temperature reaches a certain threshold, a reversible sol-gel phase transition can occur.
[0003] Poly(N,N-diethylacrylamide) hydrogel (PDEA), as a temperature-sensitive water-soluble polymer, has a critical dissolution temperature (LCST) of approximately 31°C, which closely matches human body temperature. This polymer possesses both hydrophilic and hydrophobic groups, and near the LCST, it can trigger a volume phase transition to achieve controlled release of the load, making it an ideal carrier for temperature-sensitive delivery systems. However, PDEA-based hydrogels still suffer from inherent defects such as insufficient mechanical strength and low load capacity. PDEA chains are highly flexible and prone to reorganization or breakage under external forces, resulting in poor overall compression and tensile strength. The strong hydrophilic groups of the hydrophilic monomers weaken the interaction of polymer chains, thereby reducing cross-linking density and ultimately lowering the mechanical strength of the hydrogel. Furthermore, the low density of binding sites on the PDEA molecular chains makes it difficult to form multi-point synergistic bonds. As the hydrogel swells and the molecular chains stretch, the originally limited binding sites are occupied and blocked by a large number of water molecules, significantly reducing the probability of effective contact with the load and thus lowering the load capacity.
[0004] To address the aforementioned limitations, existing technologies have optimized PDEA hydrogel systems by introducing nanomaterials. Carbon nanotubes, due to their high specific surface area and nanoscale size, can significantly improve the load-bearing capacity. Furthermore, the extremely light nature of carbon nanotubes not only enhances bioavailability but also, to some extent, strengthens the stability of the load and the mechanical strength of the hydrogel.
[0005] However, hydrogels containing carbon nanotubes often suffer from poor biocompatibility: firstly, carbon nanotubes are tubular nanostructures with sharp edges that can easily cause mechanical damage to biological components they come into contact with; secondly, carbon nanotubes are highly hydrophobic and tend to aggregate into large particles in aqueous solutions, making it difficult to achieve good dispersion and compatibility with biological systems; to solve this problem, it is usually necessary to add other biocompatible materials. Tongyao Lin disclosed a method for preparing temperature-sensitive hydrogels. This method improves the dispersibility of carbon nanotubes by modifying them with chitosan, thereby enhancing the efficiency and biocompatibility of the hydrogel in delivering the load (Lin T, Zhang J, Long H, et al. Temperature-Sensitive Hydrogels Containing Carboxylated Chitosan-Modified Carbon Nanotubes for Controlled Drug Release[J].[2025-12-15].). However, analysis revealed the following shortcomings in the above-mentioned method: Firstly, the carboxylated chitosan is adsorbed onto the carbon nanotubes through electrostatic interactions, resulting in weak binding force and easy separation of chitosan from the carbon nanotubes, thus limiting the improvement in biocompatibility. Furthermore, long-term static placement can lead to the aggregation of carbon nanotubes, forming interfacial defects with the polymer matrix and reducing the mechanical strength of the hydrogel. Summary of the Invention
[0006] To address the shortcomings of existing technologies, this invention provides a temperature-controlled hydrogel and its preparation method. The hydrogel exhibits good biocompatibility and high mechanical strength.
[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A method for preparing a temperature-controlled hydrogel includes the following steps: preparing a polyglutamic acid-methacrylate copolymer, preparing a composite chitosan, modifying fullerene with chitosan, and mixing the materials; The method for preparing polyglutamic acid-methacrylate copolymer is as follows: polyglutamic acid is added to a reaction vessel containing anhydrous dimethyl sulfoxide and stirred at 30-50 r / min for 3-4 h. After stirring, the catalyst 4-dimethylaminopyridine and the condensing agent N,N-dicyclohexylcarbodiimide are added and stirred at 30-50 r / min for 1-2 h under nitrogen protection. After stirring, activated polyglutamic acid is obtained. The temperature of the vessel is raised to 35-45℃, and glycidyl methacrylate is added dropwise. After the addition is completed, the reaction temperature is controlled at 35-45℃ and the reaction time is 8-10 h. After the reaction is completed, the polyglutamic acid-methacrylate copolymer is obtained by filtration, dialysis, washing and drying. The dropping rate of the glycidyl methacrylate is 1-2 mL / min; The polyglutamic acid, anhydrous dimethyl sulfoxide, 4-dimethylaminopyridine, and N,N-dicyclohexylcarbodiimide The mass ratio is 1.5-2.5: 85-90: 0.07-0.12: 0.8-1.3; The mass ratio of the activated polyglutamic acid to glycidyl methacrylate is 50-60:40-45.
[0008] The method for preparing composite chitosan is as follows: chitosan powder is added to a reaction vessel containing acetic acid solution and stirred evenly to form a chitosan solution. Phthalic anhydride and pyridine catalyst are added to the chitosan solution in sequence. The reaction temperature of the vessel is controlled at 55-65℃ and the reaction is carried out for 5-6 hours under light-protected conditions. After the reaction is completed, the mixture is filtered, washed and freeze-dried to obtain phthalic anhydride-modified chitosan, i.e., composite chitosan. The acetic acid solution has a mass concentration of 2-3%, and the mass ratio of chitosan powder to acetic acid solution is 2-6:85.5-88; The mass ratio of the chitosan solution, pyridine, and phthalic anhydride is 87.5-94:2-5:0.5-1.5.
[0009] The method for modifying fullerene with chitosan is as follows: Fullerene is added to a container, followed by the sequential addition of concentrated nitric acid solution and concentrated sulfuric acid solution. The mixture is refluxed and stirred at 65-75°C for 10-12 hours. After stirring, the mixture is washed, dialyzed, and lyophilized to obtain purified fullerene. The composite chitosan and the purified fullerene are then added to containers containing deionized water to obtain purified fullerene solution and composite chitosan solution, respectively. The two solutions are then ultrasonically oscillated separately in a 35-45kHz ultrasonic field for 3-4 hours at an ultrasonic power of 170-180W. After ultrasonication, the purified fullerene solution is added dropwise to the composite chitosan solution. The temperature of the reaction container is controlled at 23-27°C, and the mixture is stirred at a rate of 50-70 r / min for 8-10 hours. After the reaction, the mixture is filtered, washed, and lyophilized to obtain chitosan-modified fullerene. The mass ratio of the fullerene, concentrated nitric acid solution, and concentrated sulfuric acid solution is 1:7-9:23-27; The mass ratio of the composite chitosan to deionized water is 3-5:90-95; The mass ratio of the purified fullerene to deionized water is 1-3:95-97; The purified fullerene solution was added at a rate of 1 mL / min. The mass ratio of the composite chitosan solution to the purified fullerene solution is 4-6:1; The concentrated nitric acid solution has a mass concentration of 96-98%, and the concentrated sulfuric acid solution has a mass concentration of 96-98%.
[0010] The mixing method is as follows: Diethylacrylamide, polyglutamic acid-methacrylate copolymer and chitosan-modified fullerene are added to a container containing deionized water and stirred evenly to obtain a mixed solution. Crosslinking agent MBA and initiator KPS are added to the mixed solution and ultrasonically treated at 0-4℃ for 3-4 hours. The ultrasonic power is 170-180W and the frequency is 35-45kHz. After ultrasonic treatment, accelerator TEMED is added and the polymerization time is controlled at 6-8 hours and the polymerization temperature is 0-4℃. After polymerization, the polymer solution is poured into a mold and gelled at room temperature for 23-25 hours. After gelation, the demolded gel is immersed in pure water for 3-4 days. After immersion, a temperature-controlled hydrogel is obtained. The mass ratio of diethylacrylamide, polyglutamic acid-methacrylate copolymer, chitosan-modified fullerene, and deionized water is 8-12:3-5:0.5-2:81-88. The mass ratio of the crosslinking agent MBA, the initiator KPS, the mixed solution, and the accelerator TEMED is 0.5-0.7:0.1-0.3:90-95:0.05-0.25; The mass ratio of the demolded gel to pure water is 6.5-9.5:90-95.
[0011] Compared with the prior art, the present invention has achieved the following beneficial effects: 1. The composite chitosan prepared in this invention undergoes an acylation reaction between the amino group of chitosan and the acyl group of phthalic anhydride to form an amide bond. The modified chitosan has an additional carboxyl group, increasing the density of hydrophilic groups and improving hydrophilicity. By modifying fullerene with the hydrophilic composite chitosan, the volume effect between the grafted benzene ring structure and chitosan forms a steric barrier, preventing the aggregation of fullerene particles and improving the dispersibility of fullerene. The carboxyl group of purified fullerene combines with the hydroxyl group of composite chitosan to form a hydrogen bond, forming a hydrophilic complex with strong binding force and low dissociation, resulting in strong dispersion stability. The carboxyl group of polyglutamic acid undergoes a ring-opening reaction with the epoxy group of glycidyl methacrylate, transforming polyglutamic acid into a multi-crosslinking site active monomer. In the polymerization reaction for preparing hydrogel, a high-density network is constructed, thereby improving the mechanical strength of the hydrogel.
[0012] 2. The temperature-controlled hydrogel prepared by this invention has a swelling ratio of 19.97-21.72 g / g, exhibiting high swelling ratio, strong hydrophilicity of the hydrogel network, good fullerene dispersibility, and enhanced biocompatibility. The temperature-controlled hydrogel also has a compressive strength of 149.7-152.3 kPa, a compressive modulus of 25.9-28.6 kPa, and a fracture deformation of 70.5-73.1%, demonstrating excellent mechanical properties. Furthermore, the critical dissolution temperature of the prepared hydrogel is 31.12-31.35℃. Detailed Implementation
[0013] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention are now described.
[0014] Example 1 A method for preparing a temperature-controlled hydrogel includes the following steps: preparing a polyglutamic acid-methacrylate copolymer, preparing a composite chitosan, modifying fullerene with chitosan, and mixing the materials; (1) Preparation of polyglutamic acid-methacrylate copolymer Polyglutamic acid was added to a reaction vessel containing anhydrous dimethyl sulfoxide and stirred at 40 r / min for 3.5 h. After stirring, the catalyst 4-dimethylaminopyridine and the condensing agent N,N-dicyclohexylcarbodiimide were added and stirred at 40 r / min for 1.5 h under nitrogen protection. After stirring, activated polyglutamic acid was obtained. The temperature of the vessel was raised to 40 °C and glycidyl methacrylate was added dropwise. After the addition was completed, the reaction temperature was controlled at 40 °C and the reaction time was 9 h. After the reaction was completed, the product was filtered, dialyzed, washed and dried to obtain polyglutamic acid-methacrylate copolymer. The glycidyl methacrylate was added at a rate of 1.5 mL / min. The polyglutamic acid, anhydrous dimethyl sulfoxide, 4-dimethylaminopyridine, and N,N-dicyclohexylcarbodiimide The mass ratio is 2:87:0.10:1.1; The mass ratio of the activated polyglutamic acid to glycidyl methacrylate is 55:43.
[0015] (2) Preparation of composite chitosan Chitosan powder was added to a reaction vessel containing acetic acid solution and stirred until homogeneous to form a chitosan solution. Phthalic anhydride and pyridine catalyst were added to the chitosan solution in sequence. The reaction temperature of the vessel was controlled at 60°C and the reaction was carried out for 5.5 hours in the dark. After the reaction was completed, the chitosan was filtered, washed and freeze-dried to obtain phthalic anhydride modified chitosan, i.e., composite chitosan. The acetic acid solution has a mass concentration of 2.3%, and the mass ratio of chitosan powder to acetic acid solution is 5:87. The mass ratio of the chitosan solution, pyridine, and phthalic anhydride is 90:4:1.
[0016] (3) Chitosan-modified fullerenes Fullerene was added to a container, followed by concentrated nitric acid solution and concentrated sulfuric acid solution. The mixture was refluxed and stirred at 70°C for 11 hours. After stirring, the mixture was washed, dialyzed, and lyophilized to obtain purified fullerene. The composite chitosan and purified fullerene were added to containers containing deionized water to obtain purified fullerene solution and composite chitosan solution, respectively. The two solutions were ultrasonically vibrated separately in a 40kHz ultrasonic field for 3.5 hours with an ultrasonic power of 175W. After ultrasonication, the purified fullerene solution was added dropwise to the composite chitosan solution. The temperature of the reaction container was controlled at 25°C, and the mixture was stirred at a rate of 60r / min for 9 hours. After the reaction, the mixture was filtered, washed, and lyophilized to obtain chitosan-modified fullerene. The mass ratio of the fullerene, concentrated nitric acid solution, and concentrated sulfuric acid solution is 1:8:25. The mass ratio of the composite chitosan to deionized water is 4:93; The mass ratio of the purified fullerene to deionized water is 2:96; The purified fullerene solution was added at a rate of 1 mL / min. The mass ratio of the composite chitosan solution to the purified fullerene solution is 5:1; The concentrated nitric acid solution has a mass concentration of 97%, and the concentrated sulfuric acid solution has a mass concentration of 97%.
[0017] (4) Mixing Diethylacrylamide, polyglutamic acid-methacrylate copolymer, and chitosan-modified fullerene were added to a container containing deionized water and stirred until homogeneous to obtain a mixed solution. Crosslinking agent MBA and initiator KPS were added to the mixed solution, and the mixture was ultrasonically treated at 1°C for 3.5 h with an ultrasonic power of 175 W and a frequency of 40 kHz. After ultrasonication, accelerator TEMED was added, and the polymerization time was controlled at 7 h and the polymerization temperature at 1°C. After polymerization, the polymer solution was poured into a mold and gelled at room temperature for 24 h. After gelation, the demolded gel was immersed in pure water for 3.5 days. After immersion, a temperature-controlled hydrogel was obtained. The mass ratio of diethylacrylamide, polyglutamic acid-methacrylate copolymer, chitosan-modified fullerene, and deionized water is 11:4:1.2:86. The mass ratio of the crosslinking agent MBA, the initiator KPS, the mixed solution, and the accelerator TEMED is 0.6:0.2:93:0.15. The mass ratio of the demolded gel to pure water is 8.1:92.
[0018] Example 2 A method for preparing a temperature-controlled hydrogel includes the following steps: preparing a polyglutamic acid-methacrylate copolymer, preparing a composite chitosan, modifying fullerene with chitosan, and mixing the materials; (1) Preparation of polyglutamic acid-methacrylate copolymer Polyglutamic acid was added to a reaction vessel containing anhydrous dimethyl sulfoxide and stirred at 30 r / min for 3 h. After stirring, the catalyst 4-dimethylaminopyridine and the condensing agent N,N-dicyclohexylcarbodiimide were added and stirred at 30 r / min for 1 h under nitrogen protection. After stirring, activated polyglutamic acid was obtained. The temperature of the vessel was raised to 35 °C and glycidyl methacrylate was added dropwise. After the addition was completed, the reaction temperature was controlled at 35 °C and the reaction time was 8 h. After the reaction was completed, the polyglutamic acid-methacrylate copolymer was obtained by filtration, dialysis, washing and drying. The dropping rate of the glycidyl methacrylate is 1 mL / min; The polyglutamic acid, anhydrous dimethyl sulfoxide, 4-dimethylaminopyridine, and N,N-dicyclohexylcarbodiimide The mass ratio is 1.5:85:0.07:0.8; The activated polyglutamic acid and glycidyl methacrylate have a mass ratio of 50:40.
[0019] (2) Preparation of composite chitosan Chitosan powder was added to a reaction vessel containing acetic acid solution and stirred until homogeneous to form a chitosan solution. Phthalic anhydride and pyridine catalyst were added to the chitosan solution in sequence. The reaction temperature of the vessel was controlled at 55°C and the reaction was carried out for 5 hours in the dark. After the reaction was completed, the chitosan was filtered, washed and freeze-dried to obtain phthalic anhydride modified chitosan, i.e., composite chitosan. The acetic acid solution has a mass concentration of 2%, and the mass ratio of chitosan powder to acetic acid solution is 2:85.5. The mass ratio of the chitosan solution, pyridine, and phthalic anhydride is 87.5:2:0.5.
[0020] (3) Chitosan-modified fullerenes Fullerene was added to a container, followed by concentrated nitric acid solution and concentrated sulfuric acid solution. The mixture was refluxed and stirred at 65°C for 10 hours. After stirring, the mixture was washed, dialyzed, and lyophilized to obtain purified fullerene. The composite chitosan and purified fullerene were added to containers containing deionized water to obtain purified fullerene solution and composite chitosan solution, respectively. The two solutions were ultrasonically vibrated separately in a 35kHz ultrasonic field for 3 hours with an ultrasonic power of 170W. After ultrasonication, the purified fullerene solution was added dropwise to the composite chitosan solution. The temperature of the reaction container was controlled at 23°C, and the mixture was stirred at a rate of 50r / min for 8 hours. After the reaction, the mixture was filtered, washed, and lyophilized to obtain chitosan-modified fullerene. The mass ratio of the fullerene, concentrated nitric acid solution, and concentrated sulfuric acid solution is 1:7:23. The mass ratio of the composite chitosan to deionized water is 3:90; The mass ratio of the purified fullerene to deionized water is 1:95; The purified fullerene solution was added at a rate of 1 mL / min. The mass ratio of the composite chitosan solution to the purified fullerene solution is 4:1; The concentrated nitric acid solution has a mass concentration of 96%, and the concentrated sulfuric acid solution has a mass concentration of 96%.
[0021] (4) Mixing Diethylacrylamide, polyglutamic acid-methacrylate copolymer, and chitosan-modified fullerene were added to a container containing deionized water and stirred until homogeneous to obtain a mixed solution. Crosslinking agent MBA and initiator KPS were added to the mixed solution, and the mixture was ultrasonically treated at 0°C for 3 hours with an ultrasonic power of 170W and a frequency of 35kHz. After ultrasonic treatment, accelerator TEMED was added, and the polymerization time was controlled at 6 hours and the polymerization temperature was 0°C. After polymerization, the polymer solution was poured into a mold and gelled at room temperature for 23 hours. After gelation, the demolded gel was immersed in pure water for 3 days. After immersion, a temperature-controlled hydrogel was obtained. The mass ratio of diethylacrylamide, polyglutamic acid-methacrylate copolymer, chitosan-modified fullerene, and deionized water is 8:3:0.5:81. The mass ratio of the crosslinking agent MBA, the initiator KPS, the mixed solution, and the accelerator TEMED is 0.5:0.1:90:0.05; The mass ratio of the demolded gel to pure water is 6.5:90.
[0022] Example 3 A method for preparing a temperature-controlled hydrogel includes the following steps: preparing a polyglutamic acid-methacrylate copolymer, preparing a composite chitosan, modifying fullerene with chitosan, and mixing the materials; (1) Preparation of polyglutamic acid-methacrylate copolymer Polyglutamic acid was added to a reaction vessel containing anhydrous dimethyl sulfoxide and stirred at 50 rpm for 4 h. After stirring, the catalyst 4-dimethylaminopyridine and the condensing agent N,N-dicyclohexylcarbodiimide were added and stirred at 50 rpm for 2 h under nitrogen protection. After stirring, activated polyglutamic acid was obtained. The temperature of the vessel was raised to 45 °C and glycidyl methacrylate was added dropwise. After the addition was completed, the reaction temperature was controlled at 45 °C and the reaction time was 10 h. After the reaction was completed, the polyglutamic acid-methacrylate copolymer was obtained by filtration, dialysis, washing and drying. The dropping rate of the glycidyl methacrylate was 2 mL / min; The polyglutamic acid, anhydrous dimethyl sulfoxide, 4-dimethylaminopyridine, and N,N-dicyclohexylcarbodiimide The mass ratio is 2.5:90:0.12:1.3; The activated polyglutamic acid and glycidyl methacrylate have a mass ratio of 60:45.
[0023] (2) Preparation of composite chitosan Chitosan powder was added to a reaction vessel containing acetic acid solution and stirred until homogeneous to form a chitosan solution. Phthalic anhydride and pyridine catalyst were added to the chitosan solution in sequence. The reaction temperature of the vessel was controlled at 65°C and the reaction was carried out for 6 hours in the dark. After the reaction was completed, the chitosan was filtered, washed and freeze-dried to obtain phthalic anhydride-modified chitosan, i.e., composite chitosan. The acetic acid solution has a mass concentration of 3%, and the mass ratio of chitosan powder to acetic acid solution is 6:88. The mass ratio of the chitosan solution, pyridine, and phthalic anhydride is 94:5:1.5.
[0024] (3) Chitosan-modified fullerenes Fullerene was added to a container, followed by concentrated nitric acid solution and concentrated sulfuric acid solution. The mixture was refluxed and stirred at 75°C for 12 hours. After stirring, the mixture was washed, dialyzed, and lyophilized to obtain purified fullerene. The composite chitosan and the purified fullerene were added to containers containing deionized water to obtain purified fullerene solution and composite chitosan solution, respectively. The two solutions were ultrasonically vibrated separately in a 45kHz ultrasonic field for 4 hours with an ultrasonic power of 180W. After ultrasonication, the purified fullerene solution was added dropwise to the composite chitosan solution. The temperature of the reaction container was controlled at 27°C, and the mixture was stirred at a rate of 70r / min for 10 hours. After the reaction, the mixture was filtered, washed, and lyophilized to obtain chitosan-modified fullerene. The mass ratio of the fullerene, concentrated nitric acid solution, and concentrated sulfuric acid solution is 1:9:27. The mass ratio of the composite chitosan to deionized water is 5:95; The mass ratio of the purified fullerene to deionized water is 3:97; The purified fullerene solution was added at a rate of 1 mL / min. The mass ratio of the composite chitosan solution to the purified fullerene solution is 6:1; The concentrated nitric acid solution has a mass concentration of 98%, and the concentrated sulfuric acid solution has a mass concentration of 98%.
[0025] (4) Mixing Diethylacrylamide, polyglutamic acid-methacrylate copolymer, and chitosan-modified fullerene were added to a container containing deionized water and stirred until homogeneous to obtain a mixed solution. Crosslinking agent MBA and initiator KPS were added to the mixed solution, and the mixture was ultrasonically treated at 4°C for 4 hours with an ultrasonic power of 180W and a frequency of 45kHz. After ultrasonication, accelerator TEMED was added, and the polymerization time was controlled at 8 hours and the polymerization temperature at 4°C. After polymerization, the polymer solution was poured into a mold and gelled at room temperature for 25 hours. After gelation, the demolded gel was immersed in pure water for 4 days. After immersion, a temperature-controlled hydrogel was obtained. The mass ratio of diethylacrylamide, polyglutamic acid-methacrylate copolymer, chitosan-modified fullerene, and deionized water is 12:5:2:88. The mass ratio of the crosslinking agent MBA, the initiator KPS, the mixed solution, and the accelerator TEMED is 0.7:0.3:95:0.25. The mass ratio of the demolded gel to pure water is 9.5:95.
[0026] Comparative Example 1 In a method for preparing a temperature-controlled hydrogel, in the mixing step, ordinary polyglutamic acid is used to replace the polyglutamic acid-methacrylate copolymer, and the remaining operations are the same.
[0027] Comparative Example 2 In a method for preparing a temperature-controlled hydrogel, the step of preparing composite chitosan is omitted. In the step of modifying fullerene with chitosan, ordinary carboxylated chitosan is used to replace composite chitosan, and the rest of the operations are the same. The preparation method of the common carboxylated chitosan is as follows: chitosan powder is added to a solvent containing isopropanol and stirred evenly to form a chitosan dispersion. Sodium hydroxide solution and chloroacetic acid solution are added to the chitosan dispersion in sequence. The reaction temperature of the container is controlled at 60°C and the reaction is carried out for 4 hours under stirring. After the reaction is completed, the pH is adjusted to neutral, centrifuged, precipitated, filtered and washed, and vacuum dried to obtain carboxylated chitosan.
[0028] The sodium hydroxide solution has a mass concentration of 50%, and the chloroacetic acid solution has a mass concentration of 10%.
[0029] Experimental Example 1: Test of Swelling Rate of Temperature-Controlled Hydrogel The swelling ratio of the temperature-controlled hydrogels prepared in Examples 1-3 and Comparative Examples 1-2 was tested. The freeze-dried hydrogel samples were weighed and recorded as W. d The sample was immersed in deionized water at 22°C for 200 minutes. After 200 minutes, it was removed, excess water was quickly wiped off, and the sample was weighed again and recorded as W. e The formula for calculating the swelling ratio (SR) is: SR = (W e -W d ) / W d Each sample was tested three times, and the results are as follows: Table 1. Test results of swelling ratio of temperature-controlled hydrogel
[0030] Experimental Example 2: Mechanical Property Testing of Temperature-Controlled Hydrogels Mechanical properties of the temperature-controlled hydrogels prepared in Examples 1-3 and Comparative Examples 1-2 were tested. Cylindrical gels with a diameter of 10±0.1 mm and a height of 5±0.1 mm were placed in a universal testing machine for compressive strength testing. The temperature was controlled at 25℃ and the compression rate was 5 mm / min. The test results are shown in Table 2. Table 2 Test results of mechanical properties of temperature-controlled hydrogels
[0031] Experimental Example 3: Temperature-Sensitive Performance Test of Temperature-Controlled Hydrogel The temperature-sensitive properties of the temperature-controlled hydrogels prepared in Examples 1-3 and Comparative Examples 1-2 were tested using differential scanning calorimetry (DSC). The test conditions were: nitrogen atmosphere, heating rate 3℃ / min, temperature range 25-40℃. The test results are shown in Table 3. Table 3. Test results of the temperature-sensitive properties of the temperature-controlled hydrogel.
[0032] As shown in Table 1, the swelling ratio of the temperature-controlled hydrogels prepared in Examples 1-3 was 19.97-21.72 g / g. The hydrogels had high swelling ratios, strong hydrophilicity of the hydrogel network, and good dispersibility of chitosan-modified fullerenes in the hydrogels.
[0033] As shown in Table 2, the temperature-controlled hydrogels prepared in Examples 1-3 have a compressive strength of 149.7-152.3 kPa, a compressive modulus of 25.9-28.6 kPa, and a fracture deformation of 70.5-73.1%, indicating excellent mechanical properties. In Comparative Example 1, ordinary polyglutamic acid was used in an equal amount to replace polyglutamic acid-methacrylate copolymer in the mixing step. Since polyglutamic acid is a monomer with non-multi-crosslinking sites, it is impossible to build a high-density network in the polymerization reaction to prepare the hydrogel, resulting in weak mechanical strength of the hydrogel.
[0034] As shown in Table 3, the critical dissolution temperature of the prepared hydrogel is 31.12-31.35℃.
[0035] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for preparing a temperature-controlled hydrogel, characterized in that, The preparation method includes the following steps: preparing polyglutamic acid-methacrylate copolymer, preparing composite chitosan, modifying fullerene with chitosan, and mixing. The method for modifying fullerene with chitosan is as follows: Fullerene is added to a container, followed by the sequential addition of concentrated nitric acid solution and concentrated sulfuric acid solution. The mixture is refluxed and stirred at 65-75°C for 10-12 hours. After stirring, the mixture is washed, dialyzed, and lyophilized to obtain purified fullerene. The composite chitosan and the purified fullerene are then added to containers containing deionized water to obtain purified fullerene solution and composite chitosan solution, respectively. After ultrasonic oscillation of the two solutions, the purified fullerene solution is added dropwise to the composite chitosan solution. The mixture is stirred and reacted for 8-10 hours. After the reaction is completed, the mixture is filtered, washed, and lyophilized to obtain chitosan-modified fullerene.
2. The method for preparing a temperature-controlled hydrogel according to claim 1, characterized in that, The mass ratio of the fullerene, concentrated nitric acid solution, and concentrated sulfuric acid solution is 1:7-9:23-27; The mass ratio of the composite chitosan to deionized water is 3-5:90-95; The mass ratio of the purified fullerene to deionized water is 1-3:95-97; The purified fullerene solution was added at a rate of 1 mL / min. The mass ratio of the composite chitosan solution to the purified fullerene solution is 4-6:1; The concentrated nitric acid solution has a mass concentration of 96-98%, and the concentrated sulfuric acid solution has a mass concentration of 96-98%.
3. The method for preparing a temperature-controlled hydrogel according to claim 1, characterized in that, The method for preparing polyglutamic acid-methacrylate copolymer is as follows: polyglutamic acid is added to a reaction vessel containing anhydrous dimethyl sulfoxide and stirred for 3-4 hours. After stirring, the catalyst 4-dimethylaminopyridine and the condensing agent N,N-dicyclohexylcarbodiimide are added. The mixture is stirred at a speed of 30-50 r / min for 1-2 hours under nitrogen protection. After stirring, activated polyglutamic acid is obtained. The temperature of the vessel is raised to 35-45℃, and glycidyl methacrylate is added dropwise. After the addition is completed, the reaction temperature is controlled at 35-45℃ and the reaction time is 8-10 hours. After the reaction is completed, the polyglutamic acid-methacrylate copolymer is obtained by filtration, dialysis, washing and drying.
4. The method for preparing a temperature-controlled hydrogel according to claim 3, characterized in that, The dropping rate of the glycidyl methacrylate is 1-2 mL / min; The polyglutamic acid, anhydrous dimethyl sulfoxide, 4-dimethylaminopyridine, and N,N-dicyclohexylcarbodiimide The mass ratio is 1.5-2.5: 85-90: 0.07-0.12: 0.8-1.3; The mass ratio of the activated polyglutamic acid to glycidyl methacrylate is 50-60:40-45.
5. The method for preparing a temperature-controlled hydrogel according to claim 1, characterized in that, The method for preparing composite chitosan is as follows: chitosan powder is added to a reaction vessel containing acetic acid solution and stirred evenly to form a chitosan solution. Phthalic anhydride and pyridine catalyst are added to the chitosan solution in sequence. The reaction temperature of the vessel is controlled at 55-65℃ and the reaction is carried out for 5-6 hours under light-protected conditions. After the reaction is completed, the mixture is filtered, washed and freeze-dried to obtain phthalic anhydride-modified chitosan, i.e., composite chitosan.
6. The method for preparing a temperature-controlled hydrogel according to claim 5, characterized in that, The acetic acid solution has a mass concentration of 2-3%, and the mass ratio of chitosan powder to acetic acid solution is [missing value]. 2-6：85.5-88； The mass ratio of the chitosan solution, pyridine, and phthalic anhydride is 87.5-94:2-5:0.5-1.
5.
7. The method for preparing a temperature-controlled hydrogel according to claim 1, characterized in that, The mixing method is as follows: diethylacrylamide, polyglutamic acid-methacrylate copolymer and chitosan-modified fullerene are added to a container containing deionized water and stirred evenly to obtain a mixed solution. Crosslinking agent MBA and initiator KPS are added to the mixed solution and ultrasonically treated at 0-4℃. After ultrasonic treatment, accelerator TEMED is added and the polymerization time is controlled at 6-8h and the polymerization temperature is 0-4℃. After polymerization, the polymer solution is poured into a mold and gelled at room temperature for 23-25h. After gelation, the demolded gel is immersed in pure water for 3-4 days. After immersion, a temperature-controlled hydrogel is obtained.
8. The method for preparing a temperature-controlled hydrogel according to claim 7, characterized in that, The mass ratio of diethylacrylamide, polyglutamic acid-methacrylate copolymer, chitosan-modified fullerene, and deionized water is 8-12:3-5:0.5-2:81-88. The mass ratio of the crosslinking agent MBA, the initiator KPS, the mixed solution, and the accelerator TEMED is 0.5-0.7:0.1-0.3:90-95:0.05-0.25; The mass ratio of the demolded gel to pure water is 6.5-9.5:90-95.
9. The temperature-controlled hydrogel prepared by the method according to any one of claims 1-8.