A pH-responsive hydrogel with shape memory function, its preparation method and application
By synthesizing hydrogels through physical crosslinking of amide and carboxylic acid groups, the problems of high cost and poor mechanical properties in the hydrogel synthesis process have been solved, realizing low-cost, high-performance pH-responsive hydrogels and expanding their application range.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SOUTHWEST PETROLEUM UNIV
- Filing Date
- 2023-02-02
- Publication Date
- 2026-07-17
AI Technical Summary
Existing hydrogels suffer from problems such as high energy consumption, high cost, complex processes, poor mechanical properties, lack of responsiveness to external stimuli, and lack of shape memory function during synthesis, making it difficult to widely promote them in biomedical and industrial applications.
A monomer is formed by substitution reaction of NH2RxCOOH and acryloyl chloride, which forms a physically cross-linked hydrogel of amide and carboxylic acid groups. The shape memory function is achieved by utilizing the strong hydrogen bonds between amide groups and the weak hydrogen bonds between amide and carboxylic acid groups, which simplifies the synthesis steps and reduces costs.
This research has resulted in high-mechanical-performance hydrogels with low cost and simple processing, which possess pH responsiveness and shape memory properties, adapt to complex environmental changes, and expand the application fields of hydrogels.
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Figure CN116444818B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of polymer materials technology, specifically to a pH-responsive hydrogel with shape memory function, its preparation method, and its application. Background Technology
[0002] Hydrogels are three-dimensional polymeric composite systems formed by physical or chemical cross-linking of monomers. They possess excellent water permeability and biocompatibility, and have promising research and application prospects in medical fields such as drug release control, tissue engineering, and biosensing.
[0003] Existing technologies, such as patent document 1 (CN110885391A), disclose a method for synthesizing a hydrogel and its monomer. In this method, the monomer is mixed with water to form a solution of a certain concentration, and polymerization is initiated by ultraviolet light to form a hydrogel. This hydrogel monomer can form a hydrogel without adding any cross-linking agent, and the prepared hydrogel is more stable than acrylamide hydrogels. However, the monomer synthesis process requires frequent pH adjustment and repeated washing of the product with organic solvents. The preparation process also involves freeze-drying and rotary evaporation, resulting in high energy consumption, which is inconsistent with the concept of green development.
[0004] Patent document 2, CN112625271A, discloses a method for synthesizing a hydrogel. This hydrogel monomer contains three amide groups. Compared to traditional chemically cross-linked hydrogels, it can form a hydrogel by forming strong hydrogen bonds within the molecule without the need for a cross-linking agent. The multiple hydrogen bonds significantly enhance the strength of the hydrogel. However, the synthesis of this hydrogel monomer requires the use of toxic solvents for dissolution, necessitates a large amount of raw materials, and involves a complex preparation process with a long synthesis time, resulting in high costs and making industrial application difficult.
[0005] Patent document 3: CN111592664A discloses a method for preparing a physically cross-linked hydrogel. The hydrogel is prepared by mixing polyvinyl alcohol and ultrapure water, heating, dissolving, freezing, and thawing three times without adding any other chemical reagents. However, it has high requirements for polyvinyl alcohol as a raw material, requiring high solubility in water. Otherwise, it will affect the strength of the hydrogel. In addition, the low freezing temperature (-20°C) and long freezing time (40 min) / thawing time (natural thawing at room temperature) also increase the cost and hinder its industrial development and application.
[0006] Patent document 4: CN110193007A discloses a method for preparing a pH-responsive hydrogel. This hydrogel exhibits good pH responsiveness because the raw materials used contain γ-polyglutamic acid and sodium alginate, both natural substances containing a large number of carboxyl groups as polyanionic compounds. However, the intermolecular forces in this type of hydrogel are generated through electrostatic assembly between the added chitosan polycationic compound and the polyanionic compound. This results in a non-uniform network structure and a lack of energy dissipation mechanisms, leading to poor mechanical properties and limiting its application in practical production and daily life.
[0007] Patent document 5, CN108164636A, discloses a method for synthesizing pH-responsive copolymer nanohydrogels. This hydrogel is prepared by dispersing two monomers—one with a carboxyl group and the other with an amide group—in an aqueous solution of a surfactant and a hydrophobic initiator, reacting them in an anaerobic environment at a temperature of 40–80°C. This hydrogel can be generated in an aqueous phase without the need for large amounts of organic solvents, thus broadening the range of pH-responsive nanohydrogels. However, the synthesis method strictly requires an anaerobic environment and precise control of the ratio of the two monomers. Furthermore, since no organic solvent is used, a large amount of surfactant is needed to stably and uniformly disperse the monomers in the aqueous solution. The surfactant must be added again during the reaction, making the process cumbersome and hindering its industrial production.
[0008] Wang et al. synthesized a shape memory hydrogel using PVA and tannic acid (TA). The PVA and tannic acid form strong multiple hydrogen bonds through hydroxyl groups as "permanent" cross-linking bonds, while the "weaker" hydrogen bonds between PVA molecular chains serve as "temporary" cross-linking bonds. Therefore, the PVA-TA hydrogel has excellent temperature-responsive shape memory properties. When a hydrogel sample that has been deformed or elongated is immersed in water at 60°C for a few seconds, the hydrogel can return to its original state.
[0009] After decades of development in the field of hydrogels both domestically and internationally, hydrogels initially consisted of chemically bonded structures. Research revealed that hydrogels possess swelling properties similar to biological tissues. However, their inherent chemical toxicity inevitably limits their development in biomedical applications. Furthermore, with increasing emphasis on environmental protection, the degradation of waste hydrogels may cause harm to the surrounding environment. Therefore, researchers have gradually shifted their focus to forming hydrogels through physical cross-linking. Compared to chemical cross-linking, physical cross-linking achieves hydrogels through hydrogen bonding without coupling agents, reducing the biotoxicity of the hydrogel. However, due to the absence of chemical bonds, physically cross-linked hydrogels generally have weaker mechanical properties. Moreover, with the advancement of science and technology, people expect materials to possess more functionalities to adapt to the application requirements of complex environmental changes. Traditional hydrogels lack responsiveness to environmental stimuli, which limits their application in many fields, such as chemical sensors, artificial muscles, and drug release control.
[0010] Therefore, providing a supramolecular physical crosslinked hydrogel with relatively low monomer raw material cost, simple synthesis steps, good mechanical properties, pH responsiveness, and shape memory characteristics, and its preparation method is a technical problem that urgently needs to be solved in this field. Summary of the Invention
[0011] The purpose of this invention is to propose a pH-responsive hydrogel with shape memory function and its preparation method. This hydrogel is a purely physically cross-linked hydrogel prepared from monomers that simultaneously possess amide groups and carboxylic acid groups. This invention solves the problems of traditional physically cross-linked hydrogels, such as weak mechanical strength, lack of responsiveness to external stimuli, and lack of memory response function, which makes them difficult to apply in practice. This invention improves the possibilities for designing physically cross-linked shape memory hydrogels.
[0012] To achieve the above objectives, the present invention adopts the following technical solution:
[0013] A pH-responsive hydrogel with shape memory function, the hydrogel being composed of NH2R x COOH and acryloyl chloride are obtained by polymerization of monomers formed through a substitution reaction;
[0014] Among them, the NH2R x In COOH, R is an amide group, and x is 0, 1, or 2.
[0015] This invention provides a universal and simple method to easily insert carboxylic acid groups into monomers carrying amide groups. The synthesized monomers do not require cross-linking agents; they form hydrogels solely through physical cross-linking of their own functional groups. In the hydrogel network, the amide groups on the monomer chains form strong hydrogen bonds, which significantly improves the strength of the hydrogel. The introduced carboxylic acid groups and amide groups form weak hydrogen bonds, which promotes the entry of more water molecules into the gel network, improving the biocompatibility of the hydrogel and giving it pH-responsive functionality.
[0016] Strong hydrogen bonds between amide groups can serve as permanent crosslinking bonds, while weak hydrogen bonds between amide and carboxylic acid groups can serve as "temporary" crosslinking bonds. The former is responsible for the permanent shape, and the latter is responsible for the temporary shape. The shape memory effect can be achieved through reversible changes in the weakly switchable phase (such as temperature and pH).
[0017] Preferably, the hydrogel can be a pH-responsive hydrogel with different mechanical properties by taking the value of x.
[0018] The hydrogel monomers in this invention are designed and synthesized using inexpensive and readily available raw materials. The synthesis process is a one-step process with simple control of synthesis conditions, resulting in high product purity and high yield. Therefore, it is green, economical, and low-cost. The hydrogels formed by free radical polymerization of monomers exhibit good mechanical properties and pH-responsive characteristics, as hydrogen bonds can form between amide groups and between amide and carboxylic acid groups. By controlling the number of amide groups (x) in the raw material, hydrogels with different numbers of hydrogen bonds can be obtained, thus producing pH-responsive physical hydrogels with varying mechanical properties to meet different needs and expand the application fields of hydrogel materials.
[0019] The preparation method of the pH-responsive hydrogel with shape memory function described above includes the following specific steps:
[0020] (1) NH2R x COOH and acryloyl chloride react in an alkaline solution to yield a monomer;
[0021] (2) After dissolving the monomer, an initiator is added to carry out a polymerization reaction to obtain a pH-responsive hydrogel with shape memory function.
[0022] Preferably, the acryloyl chloride and the NH2R in step (1) x The volumetric mass percentage (in ml / mg) of COOH is as follows: 0.0928-0.1% when x=1; 0.063-0.008% when x=0; and 0.15-0.2% when x=2.
[0023] The concentration of the alkaline solution is 0.177-0.2 g / ml;
[0024] The NH2R x The mass-volume percentages of COOH and the alkaline solution are as follows: 12-14% when x = 1; 8-10% when x = 0; and 20-23% when x = 2.
[0025] Preferably, the alkaline solution in step (1) is any one of sodium hydroxide solution, potassium hydroxide solution and potassium carbonate solution.
[0026] Preferably, the reaction time in step (1) is 1 hour and the temperature is 0-3℃.
[0027] Preferably, after the reaction described in step (1) is completed, the pH of the reaction solution is adjusted to 2 with hydrochloric acid, the solid is filtered out, and the solid is recrystallized in ethanol to remove impurities and obtain the synthesized monomer.
[0028] Preferably, the dissolution in step (2) is performed using dimethyl sulfoxide solvent;
[0029] The mass ratio of dimethyl sulfoxide to water in the dimethyl sulfoxide solvent is 2:8;
[0030] The mass ratio of the monomer to the dimethyl sulfoxide solvent is 1:8.
[0031] Preferably, the initiator in step (2) is any one of ammonium persulfate, potassium persulfate, and azobisisobutyronitrile;
[0032] The mass percentage of the initiator and the monomer is 0.1-0.3%.
[0033] Preferably, the polymerization reaction conditions in step (2) are: reaction at 60-80℃ for 4-8 hours.
[0034] Applications of a pH-responsive hydrogel with shape memory function as described above, or a pH-responsive hydrogel with shape memory function prepared by the above-described method, in the preparation of chemical sensors, actuators, soft robots, bioproducts, and pharmaceuticals.
[0035] Compared with the prior art, the present invention has the following beneficial effects:
[0036] This invention prepares monomers with adjustable amide numbers in one step through a simple substitution reaction. The monomer synthesis operation is simple, the reaction conditions are easy to control, the reaction time is short, the raw material cost is low, and it is convenient for industrial production. Moreover, the monomer can form hydrogen bonds through physical cross-linking without the need for a cross-linking agent. Furthermore, by adjusting the number of amides in the monomer, the number of hydrogen bonds formed in the polymer can be controlled, and pH-responsive hydrogels with different mechanical strengths can be prepared. Attached Figure Description
[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings in this description are merely embodiments of the present invention.
[0038] Figure 1 The structure of the acryloylglycine monomer obtained in Example 1 of this invention is shown in the 1H NMR spectrum.
[0039] Figure 2 This is a schematic diagram showing the inverted effect of the hydrogel obtained in Example 1 of the present invention in a mold and the effect of its physical cross-linking to form hydrogen bonds;
[0040] Figure 3 This is a graph showing the volume change of the hydrogel obtained in Example 1 of the present invention with the pH value of the solution;
[0041] Figure 4 This is a graph showing the pH response of the hydrogel obtained in Example 1 of the present invention;
[0042] Figure 5 This is a tensile stress-displacement curve of the hydrogel obtained in Example 1 of the present invention;
[0043] Figure 6 This is a tensile stress-strain curve of the hydrogel obtained in Example 1 of the present invention;
[0044] Figure 7 This is a diagram showing the actual mechanical properties of a columnar sample prepared when the hydrogel obtained in Example 1 of this invention reaches swelling equilibrium under acidic conditions of pH=1.
[0045] Figure 8 This is a diagram illustrating the shape memory effect of the hydrogel obtained in Example 1 of the present invention. Detailed Implementation
[0046] Embodiments of the present invention are described below, examples of which are shown in the accompanying drawings. The embodiments described with reference to the drawings are exemplary and intended to explain the present invention, but are not to be construed as limiting the present invention.
[0047] Example 1
[0048] A method for preparing a pH-responsive hydrogel with shape memory function includes the following specific steps:
[0049] (1) Mix 2.2 ml of acryloyl chloride with 10 ml of 3.05 mol / L sodium hydroxide solution in a constant pressure funnel, slowly add the mixture dropwise to a round-bottom flask containing 60 ml of water and 4.0 g of NH2R1COOH, and add 10 ml of 3.05 mol / L sodium hydroxide solution. Stir for 1 h. The reaction mixture is kept at 0 °C in an ice-water bath. After completion, acidify the solution to pH = 2 with 6 mol / L hydrochloric acid, filter out the obtained solid, and crystallize it from ethanol (95%). Then filter. The filtered solid is the target product acryloylglycylglycine monomer with a yield of 63%. Because acryloyl chloride is relatively active during monomer synthesis and is easily decomposed by water, it is necessary to keep the temperature low to reduce its active properties.
[0050] The monomer reaction process is as follows:
[0051]
[0052] The obtained acryloylglycine monomer was characterized by nuclear magnetic resonance, such as... Figure 1 As shown, the structure of the synthesized acryloylglycine monomer was characterized by 1H NMR spectroscopy: 1H-NMR (400MHz, DMSO): δ 12.5 (Hh), 8.3 (Hf), 8.19 (Hd), 6.28 (Hc), 6.13 (Hb), 5.59 (Ha), 3.9 (Hg), 3.73 (He); the peak area ratio of peaks a, b, c, d, e, f and g is 1:1:1:1:2:1:2:1, which is consistent with the ratio of the number of hydrogen atoms at each position in the structural formula. Therefore, this substance can be considered to be the acryloylglycine monomer.
[0053] (2) 0.5g of acryloylglycylglycine monomer was heated and dissolved in 4.51g of dimethyl sulfoxide (DMSO) / water (DMSO / water = 5.5 / 4.5, wt / wt) mixed solvent to obtain a solution. 0.0102g of thermal initiator ammonium persulfate was added to the solution. The mixed solution was transferred into a mold and polymerized at 80℃ for 8h. The gel was then removed to obtain a pH-responsive hydrogel with shape memory function.
[0054] A schematic diagram of a physically cross-linked hydrogel synthesized from monomers is shown below. Figure 2 As shown in the figure, amide groups and carboxylic acid groups form hydrogen bonds with water molecules without crosslinking agents, thus forming hydrogels. The amide groups and carboxylic acid groups form hydrogen bonds with water molecules without any crosslinking agents, forming physically crosslinked hydrogels with a wider range of applications.
[0055] The prepared gel exhibits pH responsiveness due to the presence of amide and carboxylic acid groups, as specifically shown in the figure below. Figure 3As shown, the process of the hydrogel changing with pH value can be divided into three processes: (1) When the solution pH increases and is less than the pKa of the carboxyl group (4.28), the carboxyl group does not ionize. At this time, the gel is in a contracted state and the original volume remains basically unchanged; (2) When the solution pH is ≥ pKa and the carboxylic acid group begins to ionize, the hydrogen bonds gradually break, and the swelling ratio of the gel increases rapidly, with the highest swelling ratio reaching 6.5, showing excellent applicable environment; (3) The hydrogel reaches dissociation equilibrium. Further increasing the solution pH will lead to a further increase in the salt ion strength in the solution. Its electrostatic shielding effect causes the hydrogel to gradually tend to shrink. With the change of pH, the swelling rate of the hydrogel is changed, which is expected to have biological applications, such as drug controlled release.
[0056] To maintain good mechanical properties, the prepared polyacrylglycolglycine hydrogel was immersed in solutions with pH = 1.0 and pH = 7.0, representing acidic and neutral environments, respectively, until swelling equilibrium was reached. Figure 4 As shown, in pure water, the hydrogel exhibits irregular swelling because the pH value of the solution is higher than the pKa of glycine. However, in a solution with pH=1, the volume expansion rate is significantly reduced because the pH value of the solution is lower than the pKa of glycine, resulting in stronger mechanical properties.
[0057] The gel, having reached swelling equilibrium in a pH=1 solution, was prepared into a standard dumbbell shape and immersed in pure water for 3 days for mechanical property testing. The results are shown in the figure. Figure 5 and 6 As shown, tensile strength, tensile fracture stress and tensile elastic modulus can be obtained through stress-strain curves. The hydrogel prepared by this invention has good mechanical properties and exhibits obvious hysteresis, indicating that the hydrogel contains a large number of hydrogen bonds. Their interaction ensures that it can break after stretching, thereby consuming energy to protect the basic mechanical properties of the gel.
[0058] Figure 7 The graph shows that the columnar sample prepared after the gel swells to equilibrium in an acidic environment of pH=1 maintains high mechanical strength. The tensile test shows that the hydrogel can be stretched up to 7 times its original length, demonstrating strong toughness. The winding and knotting experiments prove that the hydrogel can easily change its state according to different production needs, and it is expected to be applied to shape memory gels.
[0059] like Figure 8As shown, when a originally curved hydrogel strip is immersed in a saturated CO2 aqueous solution and N2 is introduced to displace the CO2, the pH value of the solution gradually increases. At this time, the gel can be stretched into a relatively straight wide strip due to swelling. This shape can be temporarily fixed. When CO2 is bubbled again and the solution is tightly sealed initially, the wide strip gradually disappears and the gel gradually shrinks. With continued CO2 introduction, the gel gradually returns to its curved hydrogel strip shape. This process depends on the breaking and recombination of hydrogen bonds. After displacing CO2, acetic acid molecules are deprotonated, and the hydrogen bonds between acetic acid molecules and amide groups break. The gel absorbs water and swells, while the hydrogen bonds between amide groups are used to stabilize the basic mechanical structure of the gel. Therefore, it can be stretched and fixed into a wide strip shape. When CO2 is bubbled again, acetic acid molecules are reprotonated and re-crosslinked with the surrounding amide groups. The gel gradually shrinks and thus returns to its curved spiral shape. This provides a new approach and idea for preparing CO2-triggered shape memory hydrogels.
[0060] Example 2
[0061] A method for preparing a pH-responsive hydrogel with shape memory function includes the following specific steps:
[0062] (1) Mix 4.4 ml of acryloyl chloride with 20 ml of 3.05 mol / L sodium hydroxide solution in a constant pressure funnel, slowly add it dropwise to a round bottom flask containing 60 ml of water and 8.0 g of NH2R1COOH dissolved in it, and add 20 ml of 3.05 mol / L sodium hydroxide solution. Stir for 1 h. The reaction mixture is kept at 0 °C in an ice-water bath. After completion, acidify the solution to pH = 2 with 6 mol / L hydrochloric acid, filter out the obtained solid, and crystallize it from ethanol (95%). Then filter it. The filtered solid is the target product acryloylglycylglycine monomer with a yield of 64%.
[0063] (2) 1.02g of acryloylglycylglycine monomer was heated and dissolved in 4.0g of dimethyl sulfoxide (DMSO) / water (DMSO / water = 8 / 2, wt / wt) mixed solvent to obtain a solution. 0.0205g of thermal initiator ammonium persulfate was added to the solution. The mixed solution was transferred into a mold and polymerized at 80℃. After reacting for 8h, the gel was removed to obtain a pH-responsive hydrogel with shape memory function.
[0064] Example 3
[0065] A method for preparing a pH-responsive hydrogel with shape memory function includes the following specific steps:
[0066] (1) Mix 1.1 ml of acryloyl chloride with 10 ml of 2.0 mol / L sodium hydroxide solution in a constant pressure funnel, slowly add it dropwise to a round bottom flask containing 60 ml of water and 2.0 g of NH2R1COOH dissolved in it, and add 10 ml of 2.0 mol / L sodium hydroxide solution. Then stir for 1 h. The reaction mixture is kept at 0 °C in an ice-water bath. After completion, acidify the solution to pH=2 with 6 mol / L hydrochloric acid, filter out the obtained solid, and crystallize it from ethanol (95%). Then filter it. The filtered solid is the target product acryloylglycylglycine, with a monomer yield of 64%.
[0067] (2) 0.25g of acryloylglycine monomer was dissolved in 2.5g of dimethyl sulfoxide (DMSO) / water (DMSO / water = 6 / 4, wt / wt) mixed solvent under heating to obtain a solution. 0.005g of thermal initiator ammonium persulfate was added to the solution, the mixed solution was transferred into a mold and polymerized at 80℃ for 8h. The gel was then removed to obtain a pH-responsive hydrogel with shape memory function.
[0068] Example 4
[0069] A method for preparing a pH-responsive hydrogel with shape memory function includes the following specific steps:
[0070] (1) Mix 3.0 ml of acryloyl chloride with 15 ml of 2.0 mol / L sodium hydroxide solution in a constant pressure funnel, slowly add the mixture dropwise to a round-bottom flask containing 60 ml of water and 5.96 g of NH2R2COOH dissolved in it, and then add 15 ml of 2.0 mol / L sodium hydroxide solution. Stir for 1 h and maintain the reaction mixture at 0 °C in an ice-water bath. After the reaction is complete, acidify the solution to pH 2 with 6 mol / L hydrochloric acid, filter out the obtained solid, and crystallize it from ethanol (95%). Then filter it. The filtered solid is the target product, acryloyl glycine monomer, with a yield of 63%.
[0071] (2) 0.5 g of propylene diacylglycyl glycine monomer was dissolved in 2.0 g of dimethyl sulfoxide (DMSO) / water (DMSO / water = 8 / 2, wt / wt) mixed solvent under heating to obtain a solution. 0.01 g of thermal initiator ammonium persulfate was added to the solution, the mixed solution was transferred into a mold and polymerized at 80 °C for 8 h. The gel was then removed to obtain a pH-responsive hydrogel with shape memory function.
[0072] Example 5
[0073] A method for preparing a pH-responsive hydrogel with shape memory function includes the following specific steps:
[0074] (1) Mix 3.0 ml of acryloyl chloride with 15 ml of 2.0 mol / L sodium hydroxide solution in a constant pressure funnel, slowly add the mixture dropwise to a round bottom flask containing 60 ml of water and 2.44 g of NH2R0COOH dissolved in it, and add 15 ml of 2.0 mol / L sodium hydroxide solution. Stir for 1 h. The reaction mixture is kept at 0 °C in an ice-water bath. After the reaction is complete, acidify the solution to pH 2 with 6 mol / L hydrochloric acid, filter out the obtained solid, and crystallize it from ethanol (95%). Then filter it. The filtered solid is the target product, acryloylglycine monomer, with a yield of 63%.
[0075] (2) 0.5 g of acryloylglycine monomer was dissolved in 2.0 g of dimethyl sulfoxide (DMSO) / water (DMSO / water = 8 / 2, wt / wt) mixed solvent under heating to obtain a solution. 0.01 g of thermal initiator ammonium persulfate was added to the solution. The mixed solution was transferred to a mold and polymerized at 80 °C for 8 h. The gel was then removed to obtain a pH-responsive hydrogel with shape memory function.
[0076] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims
1. A pH-responsive hydrogel with CO2-triggered shape memory function, characterized in that, The hydrogel was obtained by polymerization of NH2CH2CONHCH2COOH and acryloyl chloride into a monomer formed by a substitution reaction. The preparation method of the hydrogel includes the following specific steps: (1) The monomer is obtained by reacting NH2CH2CONHCH2COOH and acryloyl chloride in an alkaline solution; (2) After dissolving the monomer, an initiator is added to carry out a polymerization reaction to obtain a pH-responsive hydrogel with CO2-triggered shape memory function; The volume mass percentage of acryloyl chloride and NH2CH2CONHCH2COOH in step (1) is 0.0928-0.1%; The concentration of the alkaline solution is 0.177-0.2 g / ml; The mass-volume percentage of NH₂CH₂CONHCH₂COOH and the alkaline solution is 12-14%. The reaction time in step (1) is 1 hour, and the temperature is 0-3℃; The dissolution described in step (2) uses dimethyl sulfoxide as a solvent; The mass ratio of dimethyl sulfoxide to water in the dimethyl sulfoxide solvent is 2:8; The mass ratio of the monomer to the dimethyl sulfoxide solvent is 1:
8.
2. The pH-responsive hydrogel with CO2-triggered shape memory function according to claim 1, characterized in that, The alkaline solution mentioned in step (1) is any one of sodium hydroxide solution, potassium hydroxide solution and potassium carbonate solution.
3. The pH-responsive hydrogel with CO2-triggered shape memory function according to claim 1, characterized in that, The initiator mentioned in step (2) is any one of ammonium persulfate, potassium persulfate, and azobisisobutyronitrile; The mass percentage of the initiator and the monomer is 0.1-0.3%.
4. The pH-responsive hydrogel with CO2-triggered shape memory function according to claim 1, characterized in that, The polymerization reaction conditions described in step (2) are: reaction at 60-80℃ for 4-8 hours.
5. The application of a pH-responsive hydrogel with CO2-triggered shape memory function as described in any one of claims 1-4 in the preparation of chemical sensors, actuators, soft robots, bioproducts and pharmaceuticals.