A self-gel powder with a dehydration-induced highly entangled dual-network structure and its preparation method
The carboxymethyl chitosan/polyacrylamide self-gelling powder prepared by the dehydration-induced chain entanglement strategy solves the problems of insufficient mechanical properties and inconvenient storage of traditional hydrogels, and achieves rapid self-gelling and high stability, making it suitable for wound care and biomedical fields.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-04-16
- Publication Date
- 2026-06-02
AI Technical Summary
Traditional dual-network hydrogels have insufficient mechanical properties and poor shape retention after being made into powder. They are prone to flow or deformation, and their moisture evaporates easily during long-term storage, affecting their performance and biocompatibility.
A dehydration-induced chain entanglement strategy was employed to prepare a carboxymethyl chitosan/polyacrylamide dual-network self-gel powder, including photo-initiated polymerization, thermal dehydration treatment, and freeze-drying, to form a self-gel powder with high entanglement density. The dehydration process was used to induce dense physical entanglement of polymer chains during gelation.
It enables the self-gelling powder to rapidly rebuild a stable three-dimensional network after absorbing water, exhibiting excellent shape retention and self-healing capabilities. This enhances the material's storage stability and mechanical properties, making it suitable for irregularly shaped wounds or cavitary wounds, and extending its shelf life.
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Figure CN122127662A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of gel preparation technology, specifically relating to a self-gel powder with a dehydration-induced highly entangled dual-network structure and its preparation method. Background Technology
[0002] Hydrogel dressings are three-dimensional network high-water-content materials formed by physical or chemical cross-linking with hydrophilic polymers as the backbone. The water content is usually 50%–99%. They have advantages such as high moisture retention, high breathability, strong liquid absorption, biocompatibility and flexible fit. They are the mainstream technology direction for clinical wound care and a key direction for current research and development of biomedical materials.
[0003] Traditional dual-network hydrogels generally suffer from insufficient mechanical properties, especially after being made into powder. Their water absorption and self-gelling process mainly relies on simple physical cross-linking, resulting in a gel network structure with low strength and poor stability. Such gels often have poor shape retention, easily flowing or deforming after absorbing water, making it difficult to maintain an effective shape in specific areas (such as wounds), thus affecting the therapeutic effect. In addition, traditional hydrogel dressings are prone to moisture evaporation during long-term storage, causing the material to dry out and harden, which not only makes them inconvenient to use but also reduces their biocompatibility and therapeutic efficacy. Summary of the Invention
[0004] The purpose of this invention is to provide a self-gelling powder with a dehydration-induced highly entangled dual-network structure and its preparation method.
[0005] The implementation process of this invention is as follows: A method for preparing a self-gel powder with a dehydration-induced highly entangled dual-network structure includes the following steps: (1) A precursor solution containing carboxymethyl chitosan, acrylamide, genipin, N,N'-methylenebisacrylamide and photoinitiator 2,4,6-trimethylbenzoyldiphenylphosphine oxide was photoinitiated and polymerized under ultraviolet light to form a polyacrylamide mono-network hydrogel. (2) The polyacrylamide single-network hydrogel obtained in step (1) is subjected to thermal dehydration treatment to realize the secondary cross-linking reaction of carboxymethyl chitosan and genipin, forming a highly entangled carboxymethyl chitosan / polyacrylamide double-network gel. (3) The highly entangled carboxymethyl chitosan / polyacrylamide dual network gel obtained in step (2) is pre-cooled by liquid nitrogen and then freeze-dried in a freeze dryer. After freeze-drying, the gel powder with a dehydration-induced highly entangled dual network structure is obtained by mechanical crushing.
[0006] Further, in step (1), the preparation process of the precursor solution involves dissolving carboxymethyl chitosan, acrylamide, genipin and N,N'-methylenebisacrylamide in water, adding 2,4,6-trimethylbenzoyldiphenylphosphine oxide to the mixture under stirring conditions, and removing bubbles by centrifugation.
[0007] Furthermore, the mass-to-volume ratio of the carboxymethyl chitosan, acrylamide, genipin, N,N'-methylenebisacrylamide and water is (2~4) g : (8~16) g : (0.0006~0.0012) g : (0.0017~0.0034) g : (20~40) mL.
[0008] Furthermore, the mass ratio of the carboxymethyl chitosan to 2,4,6-trimethylbenzoyl diphenylphosphine oxide is (2~4):(0.005~0.008).
[0009] Furthermore, in step (1), the wavelength of the ultraviolet light is 365 nm.
[0010] Furthermore, in step (1), the photoinitiated polymerization time is at least 5 minutes.
[0011] Further, in step (2), the thermal dehydration treatment involves placing the polyacrylamide mono-network hydrogel obtained in step (1) in an oven at 45~55℃ for dehydration treatment, and monitoring the dehydration process by weighing in real time to increase the total polymer content to 58~66 wt%.
[0012] Furthermore, in step (3), liquid nitrogen is pre-cooled for at least 10 minutes.
[0013] Furthermore, in step (3), the freeze-drying process lasts for at least 48 hours.
[0014] The self-gel powder with a dehydration-induced highly entangled dual-network structure prepared by the above method.
[0015] The design concept of this invention: This invention relates to a self-gelling powder with a dehydration-induced highly entangled dual-network structure and its preparation method. Specifically, a carboxymethyl chitosan / polyacrylamide (CMCS / PAm) rapidly absorbs water and self-gels through a dehydration-induced chain entanglement (DICE) strategy. This powder can quickly self-gel in situ after absorbing interfacial water, thus forming a tight adhesion to moist tissue surfaces. This invention aims to overcome the problems of complex methods, insufficient polymer chain entanglement density, and inconvenient product storage faced by existing technologies in preparing high-concentration dual-network hydrogels. Unlike traditional methods that rely on increasing the concentration of the precursor solution, this invention introduces a controllable dehydration step during gelation to induce dense physical entanglement of polymer chains, thereby significantly improving the mechanical properties and self-gelling ability of the final product.
[0016] The positive effects of this invention: (1) The breakthrough of this invention lies in the fundamental optimization of the preparation method. The core is the introduction of a dehydration-induced chain entanglement step, which is synergistically integrated with the secondary crosslinking process into the gel preparation process. Dehydration not only increases the polymer concentration, but more importantly, it actively induces the physical entanglement of polymer chains and promotes the chemical crosslinking reaction of CMCS, thereby achieving a fundamental optimization of the polymer network structure and obtaining a high entanglement density dual network structure that is difficult to achieve by traditional methods. Based on the above-mentioned high entanglement density dual network structure, its freeze-dried powder can quickly rebuild a stable three-dimensional network after absorbing water, exhibiting rapid self-gelling ability. More importantly, the formed gel has excellent shape retention, can adhere to the application surface and maintain a predetermined shape, and is not easy to flow or collapse.
[0017] (2) The present invention prepares the final product as a freeze-dried powder, which greatly improves the storage stability of the material, extends the shelf life, and solves the storage problem of liquid or semi-solid gel products. The powder form is convenient for transportation and storage. When used, it can be directly applied to the wound. After absorbing tissue exudate, it quickly forms a hydrogel with good shape adaptability, which is especially suitable for irregular wounds or cavitary wounds. This design ensures that the product can maintain consistent performance and reliability after long-term storage, which provides convenience for clinical use. Attached Figure Description
[0018] Figure 1 This is a schematic diagram of the preparation method of the self-gelling powder described in this invention and its water-absorbing self-gelling process; Figure 2 The graph shows a comparison of the gel structure stability of the self-gelling powder HEDN from Example 1 and the self-gelling powder DN from Comparative Example 1 after water absorption; where a) HEDN, b) DN; Figure 3The infrared spectra of HEDN gel in Example 1 and DN gel in Comparative Example 1 are shown. Figure 4 Rheological diagrams of HEDN gel in Example 1 and DN gel in Comparative Example 1; Figure 5 A comparison diagram of the mechanical properties of Comparative Example 1 DN gel and Example 1 HEDN gel; where a) DN, b) HEDN; Figure 6 This is a comparison chart of stress changes between self-gelling HEDN powder and HEDN gel after water absorption stored for 7 days in Example 1. Figure 7 Here is a SEM image of HEDN self-gel powder from Example 1; Figure 8 The graph shows the self-gelling ability of HEDN self-gelling powder in deionized water, physiological saline and pig blood in Example 1. Figure 9 The graph shows a comparison of the uniaxial tensile stress between Comparative Example 1DN gel and Example 1HEDN gel; where a) is a line graph and b) is a bar graph. Figure 10 The graphs show a comparison of the adhesion of Comparative Example 1 DN gel and Example 1 HEDN gel to pigskin; where a) is a line graph and b) is a bar graph. Detailed Implementation
[0019] The present invention will be further described below with reference to the embodiments.
[0020] This invention relates to a dehydration-induced highly entangled dual-network structure self-gelling powder and its preparation method. Specifically, it is a carboxymethyl chitosan (CMCS) / polyacrylamide (PAm) rapid water-absorbing self-gelling powder prepared through a dehydration-induced chain entanglement strategy. This provides a high-chain entanglement self-gelling powder that is easy to handle, storage-stable, and exhibits excellent mechanical properties. It can rapidly self-gel in situ after absorbing interfacial moisture and form a tight adhesion to moist tissue surfaces, creating a highly elastic, self-healing hydrogel suitable for intraoperative hemostasis, wound closure, and other applications.
[0021] First, a low-concentration mono-network gel was formed by UV-initiated polymerization of Am. Then, thermal dehydration induced dense physical entanglement of the CMCS polymer chains, simultaneously promoting the formation of a second network through genipin (GP) crosslinking of CMCS, thus constructing a CMCS / PAm dual-network hydrogel with high entanglement density. The resulting hydrogel was freeze-dried and then mechanically pulverized to finally obtain a self-gelling powder that can rapidly recover its three-dimensional network structure after water absorption and exhibits excellent mechanical properties. Figure 1 When CMCS / PAm powder comes into contact with water, water molecules penetrate into the interchain spaces, and the hydrophilic groups (-COO) of CMCS... -Upon ionization, the electrostatic repulsion between chains increases, causing the network to expand. Simultaneously, CMCS and PAm form a reversible physical cross-linked network through hydrogen bonds and ionic dipole interactions. The carboxyl groups (-COOH) and amino groups (-NH2) on the CMCS chains can form strong hydrogen bonds and electrostatic adsorption with polar groups (such as -OH, -NH2) on the surface of wet tissue, providing initial adhesion. After absorbing water, CMCS rapidly hydrates and swells, and the chain segments expand into physical cross-linking points; the PAm molecular chains form a high-strength entanglement with the CMCS chains through hydrophobic association, forming a three-dimensional interpenetrating network. This entangled structure is rapidly reconstructed through chain segment movement after water absorption, endowing the gel with high elasticity and creep resistance. This is why the powder rapidly gels and self-heals after absorbing water. Therefore, this powder can also be used as a companion to wound dressings, possessing inherent antibacterial and antioxidant capabilities, and can promote the healing of various types of wounds, including ordinary wounds, chronic wounds, and infected wounds. In addition to its excellent hemostatic and wound-healing properties, this powder is simple to prepare, significantly improves the mechanical properties, storage stability, and ease of handling of materials, making it suitable for fields such as biomedicine and flexible electronics. It is a promising candidate material for tissue regeneration.
[0022] In a first aspect, the present invention provides a method for preparing a self-gelling powder with a dehydration-induced highly entangled dual-network structure, comprising the following steps: (1) A precursor solution containing carboxymethyl chitosan, acrylamide, genipin, N,N'-methylenebisacrylamide and photoinitiator 2,4,6-trimethylbenzoyldiphenylphosphine oxide was photoinitiated and polymerized under ultraviolet light (wavelength 365 nm) for at least 5 minutes to form a polyacrylamide mono-network hydrogel. (2) The polyacrylamide single-network hydrogel obtained in step (1) is subjected to thermal dehydration treatment to realize the secondary cross-linking reaction of carboxymethyl chitosan and genipin, forming a highly entangled carboxymethyl chitosan / polyacrylamide double-network gel. (3) After precooling the highly entangled carboxymethyl chitosan / polyacrylamide dual network gel obtained in step (2) with liquid nitrogen for at least 10 minutes, it is placed in a freeze dryer for freeze drying for at least 48 hours. After freeze drying, the self-gel powder with dehydration-induced highly entangled dual network structure is obtained by mechanical crushing.
[0023] In step (1), the precursor solution is prepared by dissolving carboxymethyl chitosan, acrylamide, genipin, and N,N'-methylenebisacrylamide in water, adding 2,4,6-trimethylbenzoyldiphenylphosphine oxide to the mixture under stirring, and removing air bubbles by centrifugation. The mass-to-volume ratio of carboxymethyl chitosan, acrylamide, genipin, N,N'-methylenebisacrylamide, and water is (2~4) g: (8~16) g: (0.0006~0.0012) g: (0.0017~0.0034) g: (20~40) mL; the mass ratio of carboxymethyl chitosan to 2,4,6-trimethylbenzoyldiphenylphosphine oxide is (2~4): (0.005~0.008).
[0024] In step (2), the thermal dehydration treatment involves placing the polyacrylamide mono-network hydrogel obtained in step (1) in an oven at 45~55℃ for dehydration treatment, and monitoring the dehydration process by real-time weighing to increase the total polymer content to 58~66wt%.
[0025] Secondly, the present invention provides a novel self-gelling powder with a dehydration-induced highly entangled dual-network structure.
[0026] The reaction mechanism of this invention is as follows: A precursor solution containing carboxymethyl chitosan (CMCS), acrylamide (AAm), genipin (GP), N,N'-methylenebisacrylamide (MBAA), and the photoinitiator 2,4,6-trimethylbenzoyldiphenylphosphine oxide (TPO) is exposed to ultraviolet light, resulting in rapid photoinitiated polymerization to form a polyacrylamide mono-network hydrogel. During this stage, the crosslinking reaction between CMCS and GP proceeds slowly, meaning the polyacrylamide network forms first. Subsequently, the resulting polyacrylamide mono-network hydrogel is placed in an oven for controlled thermal dehydration at 45–55°C. This process promotes water evaporation, leading to crowding of the polymer chains and significantly enhancing the physical entanglement between them. Simultaneously, the dehydration environment accelerates the secondary crosslinking reaction between CMCS and GP, ultimately forming a highly entangled carboxymethyl chitosan / polyacrylamide bi-network gel (CMCS / PAm), increasing the total polymer content to 58–66 wt%. The obtained highly entangled carboxymethyl chitosan / polyacrylamide dual-network gel was pre-cooled with liquid nitrogen for at least 10 minutes and then freeze-dried in a freeze dryer for at least 48 hours. After freeze-drying, the gel powder with a dehydration-induced highly entangled dual-network structure was obtained by mechanical pulverization. Example 1
[0027] A method for preparing a self-gel powder with a dehydration-induced highly entangled dual-network structure includes the following steps: (1) Dissolve 2g of carboxymethyl chitosan, 8g of acrylamide, 0.0006g of genipin and 0.0017g of N,N'-methylenebisacrylamide in 20 mL of water. Add 0.005g of 2,4,6-trimethylbenzoyl diphenylphosphine oxide to the mixture under stirring, and remove bubbles by centrifugation to obtain a precursor solution. Then place the precursor solution under ultraviolet light at a wavelength of 365 nm for photoinitiated polymerization for 5 minutes to form a polyacrylamide mono-network hydrogel. (2) The polyacrylamide single-network hydrogel obtained in step (1) was placed in an oven at 50°C for dehydration treatment to achieve a secondary crosslinking reaction between carboxymethyl chitosan and genipin. The total polymer content was increased to 60 wt% by real-time weighing monitoring to form a highly entangled carboxymethyl chitosan / polyacrylamide double-network gel. (3) The highly entangled carboxymethyl chitosan / polyacrylamide dual network gel obtained in step (2) is pre-cooled by liquid nitrogen for 10 minutes and then freeze-dried in a freeze dryer for 48 hours. After freeze-drying, it is pulverized by a pulverizer to obtain a self-gel powder with a dehydration-induced highly entangled dual network structure, abbreviated as HEDN.
[0028] Comparative Example 1: The raw material ratio was changed, and no dehydration treatment was performed. The method for preparing self-gelling powder includes the following steps: (1) Dissolve 2g carboxymethyl chitosan, 8g acrylamide, 0.006g genipin, 0.017g N,N'-methylenebisacrylamide and 0.01g 2,4,6-trimethylbenzoyldiphenylphosphine oxide in 40 mL of water and remove bubbles by centrifugation to obtain a precursor solution; then place the precursor solution under ultraviolet light at a wavelength of 365 nm for photoinitiated polymerization for 5 minutes to form a polyacrylamide mono-network hydrogel; (2) The polyacrylamide mono-network hydrogel obtained in step (1) was placed at room temperature and allowed to stand for 48 hours to form a self-gel. (3) After pre-cooling the self-gel obtained in step (2) with liquid nitrogen for 10 minutes, put it into a freeze dryer for freeze drying for 48 hours. After freeze drying, it is crushed by a pulverizer to obtain self-gel powder, abbreviated as DN. Example 2
[0029] A method for preparing a self-gel powder with a dehydration-induced highly entangled dual-network structure includes the following steps: (1) Dissolve 3g carboxymethyl chitosan, 12g acrylamide, 0.001g genipin and 0.0025g N,N'-methylenebisacrylamide in 30mL of water. Add 0.007g 2,4,6-trimethylbenzoyl diphenylphosphine oxide to the mixture under stirring. Remove bubbles by centrifugation to obtain a precursor solution. Then place the precursor solution under ultraviolet light at a wavelength of 365 nm for photoinitiated polymerization for 8 minutes to form a polyacrylamide mono-network hydrogel. (2) The polyacrylamide single-network hydrogel obtained in step (1) was placed in an oven at 45°C for dehydration treatment to achieve a secondary crosslinking reaction between carboxymethyl chitosan and genipin. The total polymer content was increased to 58 wt% by real-time weighing monitoring, forming a highly entangled carboxymethyl chitosan / polyacrylamide double-network gel. (3) The highly entangled carboxymethyl chitosan / polyacrylamide dual network gel obtained in step (2) was pre-cooled by liquid nitrogen for 15 minutes and then placed in a freeze dryer for freeze drying for 50 hours. After freeze drying, it was pulverized by a pulverizer to obtain a self-gel powder with a dehydration-induced highly entangled dual network structure. Example 3
[0030] A method for preparing a self-gel powder with a dehydration-induced highly entangled dual-network structure includes the following steps: (1) Dissolve 4g carboxymethyl chitosan, 16g acrylamide, 0.0012g genipin and 0.0034g N,N'-methylenebisacrylamide in 40mL of water. Add 0.008g 2,4,6-trimethylbenzoyl diphenylphosphine oxide to the mixture under stirring. Remove bubbles by centrifugation to obtain a precursor solution. Then place the precursor solution under ultraviolet light with a wavelength of 365nm for photoinitiated polymerization for 10 minutes to form a polyacrylamide mono-network hydrogel. (2) The polyacrylamide single-network hydrogel obtained in step (1) was placed in an oven at 55°C for dehydration treatment to achieve a secondary crosslinking reaction between carboxymethyl chitosan and genipin. The total polymer content was increased to 66 wt% by real-time weighing monitoring, forming a highly entangled carboxymethyl chitosan / polyacrylamide double-network gel. (3) The highly entangled carboxymethyl chitosan / polyacrylamide dual network gel obtained in step (2) was pre-cooled by liquid nitrogen for 18 minutes and then placed in a freeze dryer for freeze drying for 52 hours. After freeze drying, it was pulverized by a pulverizer to obtain a self-gel powder with a dehydration-induced highly entangled dual network structure.
[0031] Performance testing: (1) The stability of the gel structure of the self-gelling powder HEDN in Example 1 and the self-gelling powder DN in Comparative Example 1 after water absorption is shown in the figure. Figure 2 Adding 4g of water to 1g of DN self-gel powder using a dropper takes approximately 20 seconds to form a gel, which is highly fluid and exhibits poor structural stability after gelation. Figure 2 b). In contrast, 1g of HEDN self-gelling powder gels rapidly within 5 seconds after absorbing 4g of water, forming a strong, non-flowing gel structure with excellent shape retention. Figure 2 a).
[0032] (2) Infrared spectrum Experimental procedure: The water absorption of the gel was measured using a Fourier transform infrared spectrometer (ATR-FTIR, Thermo Fisher Scientific Nicolet iS20, USA) at a depth of 400-4000 cm⁻¹. -1 Transmission characteristics within the wavenumber range.
[0033] Experimental results: The chemical structures of the self-gelling powder HEDN of Example 1 and the self-gelling powder DN of Comparative Example 1 were characterized and compared using Fourier transform infrared spectroscopy (FTIR). Figure 3 ). At 3188 cm -1 The absorption peak at 1604 cm⁻¹ is attributed to the N–H stretching vibration. -1 The absorption peak at 1658 cm⁻¹ corresponds to the C=O stretching vibration, which together confirms the existence of CMCS. -1 The C=N bond absorption peak at 1420 cm⁻¹ indicates that an effective cross-linking reaction has occurred between CMCS and GP. Furthermore, the absorption peak at 1420 cm⁻¹... -1 The C–N bond absorption peak at 1420 cm⁻¹ indicates that MBAA successfully participated in the crosslinking of the PAm network. Furthermore, the absorption peak at 1420 cm⁻¹... -1 The C–N bond absorption peaks observed indicate that MBAA successfully participated in the crosslinking of the PAm network.
[0034] (3) Further analysis of the mechanical behavior of the two gels was conducted through rheological testing. Experimental procedure: The viscoelastic behavior of the hydrogel was investigated using a rotational rheometer (Haake Mars40, Germany), with the frequency scan range set to 0.1–100 Hz. The water-absorbed gel was prepared into disc-shaped samples with a diameter of 30 mm, and the scan range was set to 0.1–100 Hz.
[0035] Experimental results: such as Figure 4 The study found that the storage modulus (G′) of both gels was higher than that of the loss modulus (G″), indicating that both exhibited gel characteristics dominated by elasticity. However, the G′ value of HEDN gel was significantly higher than that of DN gel, showing more prominent elastic solid properties.
[0036] (4) Macroscopic comparison of mechanical properties The mechanical properties of Comparative Example 1DN gel and Example 1 HEDN gel of the same length were visually compared through macroscopic tensile testing. Figure 5 .
[0037] DN gels exhibit significant brittle fracture behavior under tensile loads, and their deformation capacity is limited. Figure 5 a) indicates that its network structure is prone to catastrophic failure under stress. In contrast, HEDN gel did not fracture under the same or even greater tensile strain, exhibiting excellent ductility ( Figure 5 b).
[0038] (5) Stress changes during long-term storage The self-gelling powder HEDN from Example 1 and the HEDN gel after water absorption were stored in a bottle and left for 7 days. The stress changes were compared. Figure 6 .
[0039] from Figure 6 It can be seen that the stress of the gel gradually decreases during storage, but the stress change of the powder is negligible, indicating that the self-gel powder has good storage stability, extends the shelf life, and solves the storage problem of liquid or semi-solid gel products.
[0040] (6) SEM image Experimental procedure: After freezing, the gel sample was thoroughly dried in a freeze dryer. The dried sample surface was then subjected to platinum sputtering coating, and its microstructure was observed using scanning electron microscopy (SEM). Figure 7 ).
[0041] (7) Evaluation of self-gelling ability The self-gelling properties of HEDN self-gel powder from Example 1 were evaluated in deionized water, physiological saline, and pig blood. Figure 8 ).
[0042] Experimental procedure: Spread 1g of gel evenly in a mold, and use a dropper to add 4-8g of deionized water, physiological saline and pig blood to the powder respectively, and wait for it to form a gel.
[0043] Experimental results: HEDN gel showed good self-gelling ability in all three solutions, indicating that it has excellent hemostatic effect.
[0044] (8) Uniaxial tensile test Experimental Procedure: Uniaxial tensile tests were performed on HEDN gel and DN gel using a universal tensile testing machine (UTM 2102, equipped with a 100 N force sensor). All dimensions were measured precisely using vernier calipers. All tensile tests were conducted at room temperature at 50 mm / min. -1 The experiment was conducted at a certain rate. Each experiment was repeated at least three times.
[0045] Experimental results: such as Figure 9 a. The stress of DN gel is below 50 kPa, while the stress of HEDN gel is close to 150 kPa, approximately three times higher than that of DN gel. This difference can be visually illustrated by a bar chart. Figure 9 b).
[0046] (9) Adhesion test on pigskin Experimental procedure: Pigskin adhesion test: Two pieces of pigskin were glued together with gel and placed on a stretching machine to test their adhesion.
[0047] Experimental results: such as Figure 10 The adhesive force of HEDN gel is significantly higher than that of DN gel. The significant improvement in mechanical properties and adhesive force of HEDN gel is mainly attributed to the chain entanglement structure introduced into its network, which effectively enhances the strength and stability of the gel. The preparation method of HEDN gel described in this invention provides a practical technical solution for the development of high-performance in-situ water-absorbing self-gelling powders.
[0048] Advantages of this invention: (1) Dehydration-induced dense entanglement strategy: Compared with the traditional method of improving gel performance by preparing high-concentration polymer solutions, the dehydration-induced dense entanglement strategy of the present invention is significantly simplified. It does not require the treatment of high-viscosity solutions, but uses the physical process of dehydration to directly induce an increase in chain entanglement density and polymer concentration in the already formed gel network, thus simplifying the process.
[0049] (2) High entanglement dual network design: Through the high chain entanglement structure generated by dehydration, the HEDN self-gel powder obtained by the present invention exhibits excellent mechanical properties after absorbing water, such as higher strength, toughness and faster self-gel speed, which is due to the dense physical entanglement.
[0050] (3) Powdered storage and instant gelation: The final product is in powder form, which is easy to store and transport, and has a long shelf life, overcoming the inconvenience of hydrogels that usually require wet storage or cold chain transportation. When in use, the self-gelling powder of this invention can quickly absorb interfacial moisture and form a highly adhesive gel in situ on the target surface, which is particularly suitable for adhesion in wet environments in the biomedical field.
[0051] Other embodiments of this application will readily conceive of by those skilled in the art upon consideration of the specification and practice of the disclosure herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and embodiments are to be considered exemplary only, and this application is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope.
Claims
1. A method for preparing a self-gelling powder with a dehydration-induced highly entangled dual-network structure, characterized in that, Includes the following steps: (1) A precursor solution containing carboxymethyl chitosan, acrylamide, genipin, N,N'-methylenebisacrylamide and photoinitiator 2,4,6-trimethylbenzoyldiphenylphosphine oxide was photoinitiated and polymerized under ultraviolet light to form a polyacrylamide mono-network hydrogel. (2) The polyacrylamide single-network hydrogel obtained in step (1) is subjected to thermal dehydration treatment to realize the secondary cross-linking reaction of carboxymethyl chitosan and genipin, forming a highly entangled carboxymethyl chitosan / polyacrylamide double-network gel. (3) The highly entangled carboxymethyl chitosan / polyacrylamide dual network gel obtained in step (2) is pre-cooled by liquid nitrogen and then freeze-dried in a freeze dryer. After freeze-drying, the gel powder with a dehydration-induced highly entangled dual network structure is obtained by mechanical crushing.
2. The method for preparing the self-gelling powder with a dehydration-induced highly entangled dual-network structure according to claim 1, characterized in that: In step (1), the precursor solution is prepared by dissolving carboxymethyl chitosan, acrylamide, genipin and N,N'-methylenebisacrylamide in water, adding 2,4,6-trimethylbenzoyldiphenylphosphine oxide to the mixture under stirring, and removing bubbles by centrifugation.
3. The method for preparing the self-gelling powder with a dehydration-induced highly entangled dual-network structure according to claim 2, characterized in that: The mass-to-volume ratio of the carboxymethyl chitosan, acrylamide, genipin, N,N'-methylenebisacrylamide and water is (2~4) g : (8~16) g : (0.0006~0.0012) g : (0.0017~0.0034) g : (20~40) mL.
4. The method for preparing the self-gelling powder with a dehydration-induced highly entangled dual-network structure according to claim 2, characterized in that: The mass ratio of the carboxymethyl chitosan to 2,4,6-trimethylbenzoyl diphenylphosphine oxide is (2~4):(0.005~0.008).
5. The method for preparing the self-gelling powder with a dehydration-induced highly entangled dual-network structure according to claim 1, characterized in that: In step (1), the wavelength of the ultraviolet light is 365 nm.
6. The method for preparing the self-gelling powder with a dehydration-induced highly entangled dual-network structure according to claim 1, characterized in that: In step (1), the photoinitiated polymerization time is at least 5 minutes.
7. The method for preparing the self-gelling powder with a dehydration-induced highly entangled dual-network structure according to claim 1, characterized in that: In step (2), the thermal dehydration treatment involves placing the polyacrylamide mono-network hydrogel obtained in step (1) in an oven at 45~55℃ for dehydration treatment, and monitoring the dehydration process by real-time weighing to increase the total polymer content to 58~66wt%.
8. The method for preparing the self-gelling powder with a dehydration-induced highly entangled dual-network structure according to claim 1, characterized in that: In step (3), liquid nitrogen is pre-cooled for at least 10 minutes.
9. The method for preparing the self-gelling powder with a dehydration-induced highly entangled dual-network structure according to claim 1, characterized in that: In step (3), freeze-drying is performed for at least 48 hours.
10. The self-gel powder with a dehydration-induced highly entangled dual-network structure prepared by the method according to any one of claims 1-9.