Carboxylated hyperbranched polyether and preparation method thereof as well as bi-crosslinked hydrogel and preparation method thereof
By introducing the coordination bonds of carboxylated hyperbranched polyether and Fe3+ into the hydrogel, the high strength, stretchability and toughness of the hydrogel are achieved, solving the problem that existing hydrogels cannot have these properties.
Patent Information
- Application Number
- CN202510178160.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-18
- Publication Date
- 2025-05-23
AI Technical Summary
Existing hydrogels have shortcomings in both high strength and high tensile properties, and cannot meet these performance requirements at the same time.
Carboxylated hyperbranched polyethers were used as macromolecular crosslinking agents, and carboxylated hyperbranched polyethers with topological non-entangled geometry were prepared by self-condensation ring-opening polymerization, atom transfer radical polymerization and hydrolysis reactions, and carboxylate hyperbranched polyethers with topological non-entangled geometry were introduced into the hydrogel, and dynamic non-covalent crosslinking was carried out by binding the coordination bonds of Fe3+ and carboxyl groups.
It improves the mechanical properties of the hydrogel, gives it high strength, good stretchability and high toughness, and solves the problem that traditional hydrogels cannot have both high strength and high tensile properties.
Smart Images
Figure CN120025499A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a carboxylated hyperbranched polyether and a preparation method thereof, a double cross-linked hydrogel and a preparation method thereof, and belongs to the technical field of gel materials. Background Art
[0002] Hydrogel is a material with a three-dimensional network structure and a certain degree of flexibility. The composition of the hydrogel determines its mechanical properties and affects its performance under different pressures and its potential for application in biomedicine, soft robotics and tissue engineering. However, hydrogels generally have poor toughness and mechanical strength, which limits their application in some fields.
[0003] To address the above issues, improvements can be taken to enhance the properties of hydrogels, including chemical or / and physical crosslinking during the preparation of hydrogels. Chemical crosslinking can enhance the stability of hydrogels, and chemical crosslinkers are required during the modification process. Common chemical crosslinkers are N,N'-methylenebisacrylamide (MBA) and epichlorohydrin (ECH). Chemically crosslinked hydrogels are hydrogels that can undergo covalent bonding and transform from liquid to solid. The chemical production of hydrogels involves a variety of reactions, including small molecule crosslinking, polymer-polymer crosslinking, and photocrosslinking. Due to their high mechanical strength, chemically crosslinked hydrogels have been widely studied and applied in different fields such as pharmaceuticals, agriculture, food processing, and optical fiber. On the other hand, physical crosslinking is a reversible mechanism for preparing hydrogels. However, physically crosslinked hydrogels lack certain properties such as elasticity, stability, tensile strength, and toughness. Physically crosslinked hydrogels occur through physical interactions, so any physical changes can easily disturb the hydrogel structure. To address this issue, a dual crosslinking mechanism can be used to prepare hydrogels, in which a combination of rigid and flexible networks are integrated into the hydrogel structure. In 2015, Lin et al. (P.Lin, S.Ma, X.Wang, F.Zhou, Molecularly engineered dual-crosslinked hydrogel with ultrahigh mechanical strength, toughness, and good self-recovery, Adv.Mater.27(2015)2054-2059) prepared a dual-crosslinked hydrogel by immersing it in FeCl 3 Solution to form COO-Fe 3+ Inspired by the above research results, people have used P(AM-co-AA) and Fe 3+Introduced into various nanocomposite hydrogels, double network hydrogels or multi-crosslinked hydrogels, many hydrogels with tensile strength exceeding 1MPa were successfully prepared. Although the document improves the strength of the hydrogel by the coordination crosslinking method, the toughness of the prepared hydrogel is poor, and conventional methods are not effective in improving the toughness of the hydrogel. Summary of the invention
[0004] The purpose of the present invention is to provide a method for preparing a carboxylated hyperbranched polyether, which can solve the problem that the hydrogel currently prepared by using a macromolecular cross-linking agent cannot have both high strength and high stretchability.
[0005] Another object of the present invention is to provide a carboxylated hyperbranched polyether, which can solve the problem that the hydrogel currently prepared by using a macromolecular cross-linking agent cannot have both high strength and high stretchability.
[0006] The third object of the present invention is to provide a method for preparing a double-crosslinked hydrogel, which can solve the problem that the currently prepared hydrogel cannot have both high strength and high stretchability.
[0007] The fourth object of the present invention is to provide a double cross-linked hydrogel, which can solve the problem that current hydrogels cannot have both high strength and high stretchability.
[0008] In order to achieve the above purpose, the technical scheme adopted by the preparation method of the carboxylated hyperbranched polyether of the present invention is:
[0009] A method for preparing a carboxylated hyperbranched polyether comprises the following steps: subjecting 3-ethyl-3-epoxypropylene methanol to a self-condensation ring-opening polymerization reaction to obtain a hyperbranched polyether, subjecting the hyperbranched polyether and 2-bromoisobutyryl bromide at a mass ratio of 1:(3-4) to a reaction to obtain a macromolecular initiator, subjecting the macromolecular initiator and a polymerization monomer at a mass ratio of 10.5:(3780-4000) to an atom transfer free radical polymerization reaction to obtain a star-shaped block polymer, and finally subjecting the star-shaped block polymer to a hydrolysis reaction to obtain a carboxylated hyperbranched polyether; the polymerization monomer is tert-butyl acrylate or tert-butyl methacrylate.
[0010] The preparation method of the carboxylated hyperbranched polyether of the present invention uses the hyperbranched polyether as a mother core and a polymer chain segment containing a carboxyl group as a mother core chain arm, which can greatly increase the carboxyl content. The prepared carboxylated hyperbranched polyether has a topological non-entangled geometric shape, which can enhance the segment movement of the flexible polymer chain, and the abundant terminal carboxyl groups can effectively provide sufficient cross-linking sites, thereby improving the mechanical properties of the hydrogel. The hydrophobic association of the carboxylated hyperbranched polyether is introduced into the hydrogel network as a dynamic non-covalent cross-linking effect, which can enhance the energy dissipation capacity of the hydrogel, thereby giving the hydrogel high strength, good stretchability and high toughness.
[0011] Preferably, the preparation method of the hyperbranched polyether is as follows: 3-ethyl-3-propylene oxide methanol is mixed and reacted in a solvent under the action of a catalyst to obtain a hyperbranched polyether; the solvent is 1,2-dichloroethane or dichloromethane, the catalyst is boron trifluoride etherate, the temperature of the mixed reaction is 0 to 35° C., and the time is 48 to 50 hours.
[0012] Preferably, the method for reacting the hyperbranched polyether and 2-bromoisobutyryl bromide is as follows: first, 2-bromoisobutyryl bromide is added dropwise to a solution of the hyperbranched polyether at -5 to 5°C, mixed and reacted for 2 to 3 hours, and then continued to mix and react at room temperature for 24 to 36 hours.
[0013] Preferably, the method for subjecting a macromolecular initiator and a polymerizable monomer to an atom transfer radical polymerization reaction is as follows: subjecting a macromolecular initiator, a polymerizable monomer, copper bromide and tri[2-(dimethylamino)ethyl]amine to a polymerization reaction in a solvent under blue light; the mass ratio of the macromolecular initiator, the polymerizable monomer, copper bromide and tri[2-(dimethylamino)ethyl]amine is 10.5:(3780-4000):(0.475-0.5):(2.9-3).
[0014] Preferably, the method for hydrolyzing the star-shaped block polymer is as follows: the star-shaped block polymer and trifluoroacetic acid are mixed in a solvent for reaction for 24 to 36 hours; the volume of trifluoroacetic acid used for every 0.5 g of the star-shaped block polymer is 10 to 12 mL.
[0015] The technical solution adopted by the carboxylated hyperbranched polyether of the present invention is:
[0016] A carboxylated hyperbranched polyether prepared by the method for preparing the carboxylated hyperbranched polyether as described above.
[0017] The carboxylated hyperbranched polyether of the present invention has a topological non-entangled geometry, which can enhance the segmental motion of the flexible polymer chain, and the abundant terminal carboxyl groups can effectively provide sufficient cross-linking sites, thereby improving the mechanical properties of the hydrogel. The hydrophobic association of the carboxylated hyperbranched polyether is introduced into the hydrogel network as a dynamic non-covalent cross-linking effect, which can enhance the energy dissipation capacity of the hydrogel, thereby giving the hydrogel high strength, good stretchability and high toughness.
[0018] The technical solution adopted by the preparation method of the double cross-linked hydrogel of the present invention is:
[0019] A method for preparing a double cross-linked hydrogel comprises the following steps: polymerizing a macromolecular cross-linking agent, acrylamide, acrylic acid and N,N'-methylenebisacrylamide in a mass ratio of (0.03-0.09):2.13:0.216:0.016 in water under the action of an initiator to obtain a hydrogel, and then performing a coordination cross-linking reaction between the hydrogel and iron ions in water to obtain a double cross-linked hydrogel; the macromolecular cross-linking agent is the carboxylated hyperbranched polyether described above.
[0020] The preparation method of the double cross-linked hydrogel of the present invention uses carboxylated hyperbranched polyether as a macromolecular physical cross-linking agent, introduces it into the hydrogel structure using N,N'-methylenebisacrylamide as a chemical cross-linking agent, and utilizes Fe 3+ The coordination bonds between the carboxyl groups and the carboxyl groups are dynamically non-covalently cross-linked, which enhances the energy dissipation capacity of the hydrogel. The topological non-entangled geometry of the carboxylated hyperbranched polyether enhances the segmental motion of the flexible polymer chain, and the abundant terminal carboxyl groups can effectively provide sufficient cross-linking sites, thereby improving the mechanical properties of the hydrogel. The hydrophobic association of the hyperbranched macromolecular cross-linker and the Fe 3+ The coordination bonds between the carboxyl groups are introduced into the hydrogel network as dynamic non-covalent cross-linking effects, and double cross-linked hydrogels with chemical and physical cross-linking can be obtained, which enhances the energy dissipation capacity of the hydrogel, thereby giving the hydrogel high strength, good stretchability and high toughness.
[0021] Preferably, the initiator used to prepare the hydrogel is a photoinitiator; the photoinitiator is 2-hydroxy-methylphenylpropane-1-one; the polymerization reaction for preparing the hydrogel is carried out under ultraviolet light, the wavelength of the ultraviolet light is 365-460nm, and the time is 1-2h.
[0022] Preferably, the method for conducting a coordination crosslinking reaction between the hydrogel and iron ions in water is as follows: the hydrogel is immersed in an iron ion solution, the concentration of iron ions in the iron ion solution is 60 to 80 mmol / L, and the immersion time in the iron ion solution is 20 to 30 hours; the mass ratio of the macromolecular crosslinking agent, acrylamide, acrylic acid and N,N'-methylenebisacrylamide is (0.05 to 0.06):2.13:0.216:0.016.
[0023] The technical solution adopted by the double cross-linked hydrogel of the present invention is:
[0024] A double-crosslinked hydrogel prepared by the method for preparing the double-crosslinked hydrogel as described above.
[0025] The double cross-linked hydrogel of the present invention contains both the hydrophobic association of the hyperbranched macromolecular cross-linking agent and the Fe 3+ The coordination effect between the carboxyl group and the carboxyl group gives it high strength, good stretchability and high toughness. Brief Description of the Drawings
[0026] Figure 1 1H NMR spectrum of hyperbranched polyether HPEHO in Example 1 of the present invention 1 ;
[0027] Figure 2 13C NMR spectrum of hyperbranched polyether HPEHO in Example 1 of the present invention 13 ;
[0028] Figure 3 1H NMR spectrum of carboxylated hyperbranched polyether HPEHO-star-PAA in Example 1 of the present invention 1 ;
[0029] Figure 4 Schematic diagram of the chemical reaction equation occurring in the preparation method of the carboxylated hyperbranched polyether in Example 1 of the present invention
[0030] Figure 5 Appearance morphology diagrams of the double-crosslinked hydrogel prepared in Example 2 of the present invention and the hydrogel prepared in the comparative example Figure 5 a in is the appearance morphology diagram of the hydrogel prepared in the comparative example Figure 5 b in is the appearance morphology diagram of the double-crosslinked hydrogel prepared in Example 2
[0031] Figure 6 Schematic diagram of the tensile stress-strain curves of the double-crosslinked hydrogel prepared in Example 2 of the present invention and the hydrogel prepared in the comparative example Detailed Description of the Invention
[0032] The preparation method of the carboxylated hyperbranched polyether of the present invention is a pioneering invention. The preparation method of the carboxylated hyperbranched polyether of the present invention uses hyperbranched polyether as the parent nucleus and polymer segments containing carboxyl groups as the parent nucleus chain arms, which can greatly increase the carboxyl content. The prepared carboxylated hyperbranched polyether has a topological non-entangled geometry, which can enhance the segmental motion of flexible polymer chains. The abundant terminal carboxyl groups can effectively provide sufficient crosslinking sites, thereby improving the mechanical properties of the hydrogel.
[0033] Various nanocomposite hydrogels and multi-network hydrogels usually involve complex and multi-step modification or synthesis routes. Compared with multi-network hydrogels, introducing dynamic interactions or new cross-linkers into hydrogels is a simpler and more effective way to improve their mechanical properties. For example, compared with small molecule cross-linkers, macromolecular cross-linkers can introduce more free-moving segments into the network, thereby enhancing stretchability. However, the above method still cannot produce hydrogels with both high strength and high stretchability (high elongation at break), because high stretchability requires dynamic interactions and flexible segment movement, while high strength is usually obtained through abundant cross-linking sites and rigid polymer segments.
[0034] 1. The specific embodiments of the carboxylated hyperbranched polyether and the preparation method thereof of the present invention are as follows:
[0035] Example 1
[0036] The preparation method of the carboxylated hyperbranched polyether of the present embodiment specifically comprises the following steps:
[0037] (1) Preparation of macromolecular initiator
[0038] First, a four-necked round-bottom flask equipped with a mechanical stirrer, a constant pressure dropping funnel, and a thermometer was heated with N 2 Degas for at least 30 minutes, then add 80 mL of 1,2-dichloroethane and 7.097 g of boron trifluoride etherate to the flask via a syringe. Subsequently, dilute 3-ethyl-3-epoxypropylene methanol (the molar ratio of 3-ethyl-3-epoxypropylene methanol to boron trifluoride etherate is 2:1) with 80 mL of 1,2-dichloroethane, and slowly add the diluted solution to the flask through a dropping funnel. The entire dropping process is completed at room temperature. Finally, the material in the flask is stirred for reaction (self-condensation ring-opening polymerization reaction) at 25°C for 48 hours. After the reaction, the reacted system is repeatedly precipitated in deionized water several times, and then dried overnight at 80°C under vacuum conditions to obtain a white powdery polymer, which is a hyperbranched polyether, labeled as HPEHO. Hyperbranched polyether HPEHO 1 H NMR spectrum Figure 1 As shown, 13 C NMR spectrum Figure 2 shown.
[0039] 0.5 g of hyperbranched polyether HPEHO was dissolved in 15 mL of anhydrous N-methylpyrrolidone at room temperature, and the HPEHO polymer solution was placed in an ice-water bath for 30 min. Then, 1.48 g of 2-bromoisobutyryl bromide was dissolved in 5 mL of anhydrous N-methylpyrrolidone under constant stirring, and then added dropwise to the HPEHO polymer solution in the ice-water bath, kept in an ice-water bath at 0°C for 2 h, and then reacted at room temperature for 24 h. The system after the reaction was concentrated by vacuum distillation, diluted with dichloromethane, and then washed three times with a saturated sodium bicarbonate aqueous solution and deionized water respectively. After the organic layer was concentrated, it was dissolved with a small amount of THF, precipitated three times in an excess of methanol / water mixed solution (volume ratio of 1:1), and vacuum dried at 50°C to obtain a light yellow product, which was a macromolecular initiator, marked as HPEHO-Br.
[0040] (2) Preparation of carboxylated hyperbranched polyether
[0041] 10.5 mg of macroinitiator HPEHO-Br, 3.78 g of tert-butyl acrylate, 0.475 mg of copper bromide, 2.9 mg of tris[2-(dimethylamino)ethyl]amine and 18 mL of N,N-dimethylformamide were added to an ampoule, nitrogen was bubbled for 1 h to remove oxygen in the system and then sealed. At room temperature and under stirring conditions, the ampoule was irradiated with 460 nm blue light (300 r, 5 W) for 2 h to allow the monomer to polymerize, and a fan was used to cool the reaction system during this period. After the polymerization reaction is completed, the crude product obtained by the polymerization reaction is diluted with tetrahydrofuran and passed through a neutral alumina column to remove the catalyst in the reaction system. The liquid obtained by column chromatography separation is then concentrated by rotary evaporation, and the concentrated liquid is then added dropwise into a cold mixed solution of methanol and water (methanol: water = 1:1, v / v) for precipitation. The precipitation operation is repeated twice, and the precipitate is dried in a vacuum oven at 40°C for 12 hours to obtain a white solid product, namely the star block polymer (HPEHO-star-PtBA).
[0042] 0.5 g of star-shaped block polymer HPEHO-star-PtBA was dissolved in 30 mL of dichloromethane to obtain a star-shaped block polymer solution. 10 mL of trifluoroacetic acid was slowly added dropwise to the star-shaped block polymer solution, and then stirred at room temperature for 24 h to ensure that the hydrolysis reaction was complete. After the hydrolysis reaction was completed, the mixed solution was poured out, and the hydrolysis product precipitated at the bottom of the bottle was dissolved with methanol. Then, dichloromethane was used as a precipitant and purified by precipitation method 3 times. The final product was collected and vacuum dried at room temperature to obtain a carboxylated hyperbranched polyether, which was recorded as HPEHO-star-PAA. 1 H NMR spectrum Figure 3 As shown, Figure 1-3The chemical shift in stands for chemical shift.
[0043] The chemical reaction equation occurring in the preparation method of the carboxylated hyperbranched polyether of this embodiment is as follows: Figure 4 As shown, among which, BF 3 ·Et 2 O represents boron trifluoride etherate, DCM represents dichloromethane, BiBB represents 2-bromoisobutyryl bromide, NMP represents N-methylpyrrolidone, tBA represents tert-butyl acrylate, Me6TREN represents tris[2-(dimethylamino)ethyl]amine, TFA represents trifluoroacetic acid, and rt represents room temperature.
[0044] 2. Specific examples of the double cross-linked hydrogel and its preparation method of the present invention are as follows:
[0045] Example 2
[0046] The preparation method of the double cross-linked hydrogel of this embodiment specifically comprises the following steps:
[0047] First, 0.030 g of the carboxylated hyperbranched polyether HPEHO-star-PAA prepared in Example 1 was dissolved in 15 g of deionized water to obtain a carboxylated polyether solution, and then 2.130 g of acrylamide, 0.216 g of acrylic acid, 0.016 g of N,N'-methylenebisacrylamide and 0.009 g of Irgacure 1173 (the chemical name of Irgacure 1173 is 2-hydroxy-methylphenylpropane-1-one) were added to the carboxylated polyether solution, and stirred evenly to obtain a mixed solution. The mixed solution was then ultrasonically treated for 5 min and degassed with nitrogen for 10 min. After that, the mixed solution was transferred to a glass culture dish and then placed under ultraviolet light (365 nm, 8 W) for 1 h to obtain a hydrogel. The hydrogel was then immersed in a ferric chloride solution with a concentration of 80 mmol / L at room temperature for 24 h, and then the copolymer after soaking in the ferric chloride solution was immersed in 2 L of deionized water to remove excess Fe 3+ The water was changed every 3 h and the double cross-linked hydrogel was obtained after immersion for 48 h, which was labeled as P(AAm-co-AA) / HPEHO-star-PAA / Fe 3+ Hydrogel.
[0048] Example 3
[0049] The preparation method of the double cross-linked hydrogel of this embodiment specifically comprises the following steps:
[0050] First, 0.060 g of the carboxylated hyperbranched polyether HPEHO-star-PAA prepared in Example 1 was dissolved in 15 g of deionized water to obtain a carboxylated polyether solution, and then 2.130 g of acrylamide, 0.216 g of acrylic acid, 0.016 g of N,N'-methylenebisacrylamide and 0.009 g of Irgacure 1173 (the chemical name of Irgacure 1173 is 2-hydroxy-methylphenylpropane-1-one) were added to the carboxylated polyether solution, and stirred evenly to obtain a mixed solution. The mixed solution was then ultrasonically treated for 5 min and degassed with nitrogen for 10 min. After that, the mixed solution was transferred to a glass culture dish and then placed under ultraviolet light (365 nm, 8 W) for 1 h to obtain a hydrogel. The hydrogel was then immersed in a ferric chloride solution with a concentration of 80 mmol / L at room temperature for 24 h, and then the copolymer after soaking in the ferric chloride solution was immersed in 2 L of deionized water to remove excess Fe 3+ The water was changed every 3 h and the double cross-linked hydrogel was obtained after immersion for 48 h, which was labeled as P(AAm-co-AA) / HPEHO-star-PAA / Fe 3+ Hydrogel.
[0051] Example 4
[0052] The preparation method of the double cross-linked hydrogel of this embodiment specifically comprises the following steps:
[0053] First, 0.090 g of the carboxylated hyperbranched polyether HPEHO-star-PAA prepared in Example 1 was dissolved in 15 g of deionized water to obtain a carboxylated polyether solution, and then 2.130 g of acrylamide, 0.216 g of acrylic acid, 0.016 g of N,N'-methylenebisacrylamide and 0.009 g of Irgacure 1173 (the chemical name of Irgacure 1173 is 2-hydroxy-methylphenylpropane-1-one) were added to the carboxylated polyether solution, and stirred evenly to obtain a mixed solution. The mixed solution was then ultrasonically treated for 5 min and degassed with nitrogen for 10 min. After that, the mixed solution was transferred to a glass culture dish and then placed under ultraviolet light (365 nm, 8 W) for 1 h to obtain a hydrogel. The hydrogel was then immersed in a ferric chloride solution with a concentration of 80 mmol / L at room temperature for 24 h, and then the copolymer after soaking in the ferric chloride solution was immersed in 2 L of deionized water to remove excess Fe 3+ The water was changed every 3 h and the double cross-linked hydrogel was obtained after immersion for 48 h, which was labeled as P(AAm-co-AA) / HPEHO-star-PAA / Fe 3+ Hydrogel.
[0054] 3. Comparison
[0055] The only difference between the preparation method of the hydrogel in this comparative example and the preparation method of the hydrogel in Example 2 is that the mass of the carboxylated hyperbranched polyether HPEHO-star-PAA in the preparation method of the hydrogel in this comparative example is 0, that is, no carboxylated hyperbranched polyether HPEHO-star-PAA is used.
[0056] Experimental Example 1
[0057] In this experimental example, the appearance morphology of the double cross-linked hydrogel prepared in the example and the hydrogel prepared in the comparative example was characterized by SEM. The appearance morphology of the double cross-linked hydrogel prepared in Example 2 and the hydrogel prepared in Comparative Example 1 is as follows: Figure 5 As shown. Figure 5 It can be seen that the cross section of the hydrogel prepared in the comparative example presents a homogeneous porous network structure ( Figure 5 a), while the double cross-linked hydrogel prepared in Example 2 shrinks due to the shrinkage of the voids during the freeze-drying process ( Figure 5 In b), no obvious porous microstructure appears, indicating that the introduction of HPEHO-star-PAA increases the cross-linking density of the hydrogel.
[0058] Experimental Example 2
[0059] In this experimental example, the physical and mechanical properties of the double cross-linked hydrogel prepared in the example and the hydrogel prepared in the comparative example were tested. The tensile stress-strain curves of the double cross-linked hydrogel prepared in Example 2 and the hydrogel prepared in the comparative example are shown in FIG. Figure 6 As shown ( Figure 6 The abscissa strain represents strain, the ordinate stress represents stress, the red curve represents the double cross-linked hydrogel prepared in Example 2, and the black curve represents the hydrogel prepared in the comparative example). The tensile strength, toughness and elongation at break of the double cross-linked hydrogels prepared in Examples 2-4 and the comparative example and the hydrogel prepared in the comparative example are shown in Table 1.
[0060] Table 1 Tensile strength, toughness and elongation at break of hydrogels prepared in Examples 2-4 and Comparative Examples
[0061] Hydrogel Tensile strength(MPa) Elongation at break (%) <![CDATA[Toughness (MJ / m 3 )]]> Example 2 2.67 322.92 499.94 Example 3 3.68 573.62 1409.05 Example 4 2.29 321.86 416.53 Comparative Example 2.18 258.41 303.23
[0062] As shown in Table 1, the content of HPEHO-star-PAA has a significant effect on the mechanical properties of the hydrogel. Increasing the content of HPEHO-star-PAA can significantly improve the mechanical properties of the hydrogel. With the increase of the content of HPEHO-star-PAA, the tensile strength, elongation and elastic modulus of the hydrogel increase. The maximum tensile strength of the hydrogel is 3.68MPa, the maximum elongation at break is 573.62%, and the corresponding toughness is relatively high, which is 1409.05MJ / m 3This is because when the HPEHO-star-PAA content increases, more carboxyl groups will bind to Fe 3+ The coordination effect is formed, which increases the cross-linking density of the network. At the same time, the hyperbranched structure of the cross-linker HPEHO-star-PAA plays a key role in the strengthening and toughening of the hydrogel.
Claims
1. A method for preparing a carboxylated hyperbranched polyether, characterized in that: The following steps are involved: 3-ethyl-3-propylene oxide methanol is subjected to a self-condensation ring-opening polymerization reaction to obtain a hyperbranched polyether, and then the hyperbranched polyether and 2-bromoisobutyryl bromide in a mass ratio of 1:(3-4) are reacted to obtain a macromolecular initiator, and then the macromolecular initiator and a polymerization monomer in a mass ratio of 10.5:(3780-4000) are subjected to an atom transfer free radical polymerization reaction to obtain a star-shaped block polymer, and finally the star-shaped block polymer is subjected to a hydrolysis reaction to obtain a carboxylated hyperbranched polyether; the polymerization monomer is tert-butyl acrylate or tert-butyl methacrylate.
2. The method for preparing a carboxylated hyperbranched polyether according to claim 1, wherein The preparation method of the hyperbranched polyether is as follows: 3-ethyl-3-propylene oxide methanol is mixed and reacted in a solvent under the action of a catalyst to obtain a hyperbranched polyether; the solvent is 1,2-dichloroethane or dichloromethane, the catalyst is boron trifluoride etherate, the temperature of the mixed reaction is 0-35°C, and the time is 48-50h.
3. The method for preparing a carboxylated hyperbranched polyether as claimed in claim 1 or 2, wherein: The method for reacting the hyperbranched polyether and 2-bromoisobutyryl bromide is as follows: first, 2-bromoisobutyryl bromide is added dropwise to a solution of the hyperbranched polyether at -5 to 5°C, mixed and reacted for 2 to 3 hours, and then continued to mix and react at room temperature for 24 to 36 hours.
4. The method for preparing a carboxylated hyperbranched polyether according to claim 1, wherein The method for conducting an atom transfer radical polymerization reaction of a macromolecular initiator and a polymerization monomer is as follows: a macromolecular initiator, a polymerization monomer, copper bromide and tri[2-(dimethylamino)ethyl]amine are subjected to a polymerization reaction in a solvent under blue light; the mass ratio of the macromolecular initiator, the polymerization monomer, copper bromide and tri[2-(dimethylamino)ethyl]amine is 10.5:(3780-4000):(0.475-0.5):(2.9-3).
5. The method for preparing the carboxylated hyperbranched polyether according to claim 1 or 4, wherein: The method for hydrolyzing the star-shaped block polymer is as follows: the star-shaped block polymer and trifluoroacetic acid are mixed in a solvent for reaction, and the mixing reaction time is 24 to 36 hours; the volume of trifluoroacetic acid used for every 0.5 g of the star-shaped block polymer is 10 to 12 mL.
6. A carboxylated hyperbranched polyether prepared by the method for preparing a carboxylated hyperbranched polyether as claimed in any one of claims 1 to 5.
7. A method for preparing a double cross-linked hydrogel, characterized in that: The following steps are involved: A macromolecular crosslinking agent, acrylamide, acrylic acid and N,N'-methylenebisacrylamide in a mass ratio of (0.03-0.09):2.13:0.216:0.016 are polymerized in water under the action of an initiator to obtain a hydrogel, and then the hydrogel and iron ions are coordinated and crosslinked in water to obtain a double crosslinked hydrogel; the macromolecular crosslinking agent is the carboxylated hyperbranched polyether as described in claim 6.
8. The method for preparing the double cross-linked hydrogel according to claim 7, characterized in that: The initiator used to prepare the hydrogel is a photoinitiator; the photoinitiator is 2-hydroxy-methylphenylpropane-1-one; the polymerization reaction for preparing the hydrogel is carried out under ultraviolet light, the wavelength of the ultraviolet light is 365-460nm, and the time is 1-2h.
9. The method for preparing the double cross-linked hydrogel according to claim 7, characterized in that: The method for carrying out coordination crosslinking reaction between hydrogel and iron ions in water is as follows: immersing the hydrogel in an iron ion solution, the concentration of iron ions in the iron ion solution is 60-80 mmol / L, and the immersion time in the iron ion solution is 20-30 hours; the mass ratio of the macromolecular crosslinking agent, acrylamide, acrylic acid and N,N'-methylenebisacrylamide is (0.05-0.06):2.13:0.216:0.
016.
10. A double cross-linked hydrogel prepared by the method for preparing a double cross-linked hydrogel according to any one of claims 7 to 9.