A co2-responsive gel particle and a method for preparing the same

Abstract

The present application relates to the technical field of polymer gel, and particularly relates to a CO2-responsive gel particle and a preparation method thereof. The CO2-responsive gel particle is prepared by the following steps: impregnating an initial cross-linked hydrogel prepared from raw materials including a certain proportion of biological macromolecules, a first CO2-responsive monomer, a second CO2-responsive monomer, an organic cross-linking agent, a nano-enhancing agent, an initiator and deionized water into a cationic solution for re-cross-linking, drying, and crushing to obtain the CO2-responsive gel particle; the first CO2-responsive monomer is a self-cross-linking CO2-responsive monomer; and the second CO2-responsive monomer is a non-self-cross-linking CO2-responsive monomer. The present application endows the PPG with CO2 resistance while effectively maintaining the temperature resistance and mechanical strength of the PPG, thereby effectively solving the gas channeling problem in the CO2 displacement process.

Description

Technical Field

[0001] This invention relates to the field of polymer gel technology, and in particular to a CO2-responsive gel particle and its preparation method. Background Technology

[0002] In the later stages of oilfield development, formation energy is rapidly depleted. To continue crude oil extraction, it is often necessary to replenish formation energy through water or gas injection. CO2, as a greenhouse gas, can dissolve in crude oil, reducing its viscosity and interfacial tension, and improving its expansibility and mobility ratio. Furthermore, CO2 can dissolve organic plugging materials and improve wettability, thereby increasing oil production. CO2 flooding, as one of the most effective methods for enhancing oil recovery, has been widely used worldwide. It not only improves oil recovery but also sequesters carbon dioxide in the reservoir, reducing the greenhouse gas effect.

[0003] However, the presence of large pores and fractures in the reservoir exacerbates its heterogeneity, leading to gas channeling during CO2 displacement. To address this issue, various profile control agents have been developed.

[0004] Pre-crosslinked particulate gel (PPG), as a type of polymer gel, has gained widespread application due to its excellent comprehensive properties. PPG is a highly absorbent polymer material with a three-dimensional network structure. Due to the large number of hydrophilic groups in its chemical structure, it can absorb several to hundreds of times its own weight in water. Furthermore, because the crosslinking reaction of PPG is completed in ground-based equipment, it has advantages such as adjustable particle size, stable chemical structure, and resistance to temperature and salt. However, in the presence of CO2, traditional PPG often undergoes dehydration or a sharp decrease in strength due to the acidic conditions caused by CO2. The lower strength severely limits its use, making its CO2 blocking ability insufficient and thus unable to effectively suppress gas channeling during CO2 displacement, thereby affecting its effect on improving reservoir heterogeneity. Currently, the solution to this problem is to prepare CO2-responsive PPG, which can undergo additional volume swelling upon encountering CO2. However, while PPG obtained through this method has certain CO2 resistance, its temperature resistance and strength are still insufficient, thus limiting its widespread application. Summary of the Invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide a CO2-responsive gel particle and its preparation method, which endows PPG with CO2 resistance while effectively maintaining its temperature resistance and mechanical strength, thereby effectively solving the gas channeling problem in the CO2 displacement process.

[0006] This invention provides CO2-responsive gel particles, obtained by impregnating an initially cross-linked hydrogel in a cationic solution for further cross-linking, followed by drying and pulverization. The initially cross-linked hydrogel is prepared from raw materials including biomacromolecules, a first CO2-responsive monomer, a second CO2-responsive monomer, an organic cross-linking agent, a nano-reinforcing agent, an initiator, and deionized water. The mass ratio of the biomacromolecules, the first CO2-responsive monomer, the second CO2-responsive monomer, the organic cross-linking agent, the initiator, and deionized water is 0.1–5:0.2–2:0.5–5:0.01–0.1:0.01–0.5:5–40. The ratio of the biomacromolecules to the nano-reinforcing agent is 0.1–5 g:0.1–1 mL. The first CO2-responsive monomer is a self-cross-linking CO2-responsive monomer, and the second CO2-responsive monomer is a non-self-cross-linking CO2-responsive monomer. This invention introduces nano-reinforcing agents and multi-crosslinked structures while constructing CO2-responsive PPG, endowing PPG with CO2 resistance while effectively maintaining its temperature resistance and mechanical strength, thereby effectively solving the gas channeling problem in the CO2 displacement process. Attached Figure Description

[0007] Figure 1 This is a SEM image of the high-strength CO2-responsive gel particles in Example 1 of the present invention;

[0008] Figure 2 This is a graph showing the swelling rate of the high-strength CO2-responsive gel particles in water and saturated H2CO3 solution in Example 1 of the present invention.

[0009] Figure 3 This is a strength test diagram of conventional polyacrylamide gel particles;

[0010] Figure 4 This is a strength test diagram of the high-strength CO2-responsive gel particles in Example 1 of the present invention. Detailed Implementation

[0011] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0012] CO2 responsiveness: PPG absorbs water and swells upon contact with water. However, when CO2 is continuously introduced into the water, PPG will swell further on top of its original swelling. This is known as the CO2 responsiveness of PPG. The normal behavior of PPG is the opposite; the swelling rate decreases or even dehydrates after CO2 is introduced.

[0013] This invention provides a CO2-responsive gel particle, which is obtained by impregnating an initially cross-linked hydrogel into a cationic solution for further cross-linking, followed by drying and pulverization.

[0014] The initially cross-linked hydrogel is prepared from raw materials including biomacromolecules, a first CO2-responsive monomer, a second CO2-responsive monomer, an organic cross-linking agent, a nano-reinforcing agent, an initiator, and deionized water;

[0015] The mass ratio of the biomacromolecule, the first CO2-responsive monomer, the second CO2-responsive monomer, the organic crosslinking agent, the initiator, and the deionized water is 0.1–5: 0.2–2: 0.5–5: 0.01–0.1: 0.01–0.5: 5–40; the dosage ratio of the biomacromolecule to the nano-reinforcing agent is 0.1–5 g: 0.1–1 mL.

[0016] The first CO2-responsive monomer is a self-crosslinking CO2-responsive monomer; the second CO2-responsive monomer is a non-self-crosslinking CO2-responsive monomer.

[0017] In some embodiments of the present invention, the biomacromolecule is at least one selected from guar gum, chitosan, gelatin, starch, sodium alginate, and hydroxymethyl cellulose. The present invention introduces biomacromolecules, which have the advantages of being environmentally friendly, inexpensive, and widely available. Among them, sodium alginate macromolecules contain a large number of carboxylic acid groups, which can form coordination crosslinks with high-valence metal ions.

[0018] In some embodiments of the present invention, the first CO2-responsive monomer is at least one of N,N-dimethylacrylamide, N-hydroxymethylacrylamide, dicyclopentadiene acrylate, diacetone acrylamide, and hydroquinone acrylate.

[0019] In some embodiments of the present invention, the second CO2-responsive monomer is two of acrylamide, acrylic acid, 2-acrylamido-2-methylpropanesulfonic acid, N-acryloylmorpholine, 1-vinylimidazolium, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, N-vinylpyrrolidone, and N,N-diethylacrylamide.

[0020] This invention employs a combination of a specific first CO2-responsive monomer and a second CO2-responsive monomer to impart CO2-responsive properties to the polymer. The CO2-responsive monomer also includes a self-crosslinking CO2-responsive monomer, which can interact well with other components.

[0021] The present invention further selects three specific CO2-responsive monomers for copolymerization, which not only have CO2-responsive groups, but also have large side chain groups, which can simultaneously endow the polymer with CO2-responsive properties and good temperature and salt resistance.

[0022] In some embodiments of the present invention, the organic crosslinking agent is at least one selected from polyethyleneimine, branched polyethyleneimine, N,N-methylenebisacrylamide, ethoxylated trimethylolpropane triacrylate, and hexamethylenebisacrylamide. The present invention introduces an organic crosslinking agent (such as N,N-methylenebisacrylamide) as an organic crosslinking point, enabling monomers to crosslink into a network structure, thereby constructing a chemical crosslinking point.

[0023] In some embodiments of the present invention, the surface of the nano-reinforcing agent has vinyl groups capable of cross-linking reactions, thus it can act as a nano-crosslinking agent and reinforcing agent, thereby endowing the polymer network with superior performance. The nano-reinforcing agent is a microsphere with a size of 50–100 nm. The nano-reinforcing agent is synthesized using a sol-gel method. Specifically, the nano-reinforcing agent is vinyl silica nanoparticles (VSNPs), and its preparation method includes the following steps:

[0024] a) An aqueous solution of sodium dodecylbenzenesulfonate (SDBS) was stirred and mixed with vinyltriethoxysilane (VTES) to obtain a mixture;

[0025] b) Add ammonia water dropwise into the stirred mixture and stir to react, thereby obtaining vinyl silica nanoparticles (VSNPs), which are nano-reinforcing agents.

[0026] In step a):

[0027] The concentration of the aqueous solution of sodium dodecylbenzenesulfonate (SDBS) is 0.5–1.5 mmol / L, for example, 1.2 mmol / L.

[0028] The mass ratio of sodium dodecylbenzenesulfonate to vinyltriethoxysilane is 1:200 to 400, for example, 1:301.

[0029] The mixing method is magnetic stirring. The mixing time is 1 to 3 hours, for example, 2 hours.

[0030] In step b):

[0031] The mass concentration of the ammonia water is 25% to 28%.

[0032] The ratio of the total mass of sodium dodecylbenzenesulfonate and vinyltriethoxysilane to the amount of ammonia is 7-8 g:1 mL, for example, 7.6252 g:1 mL.

[0033] The temperature of the stirring reaction is 30–70°C, for example, 50°C; the time is 24–48 hours, for example, 24 hours. The stirring speed is 200–600 rpm, specifically 400 rpm.

[0034] In some embodiments of the present invention, the initiator is one of ammonium persulfate, potassium persulfate, azobisisobutyronitrile, and azobisisobutyramidine hydrochloride.

[0035] In some embodiments of the present invention, the mass ratio of the biomacromolecule, the first CO2-responsive monomer, the second CO2-responsive monomer, the organic crosslinking agent, the initiator, and the deionized water is 0.2:0.99:1.498:0.019:0.0285:7.2, 5:0.49:1.03:0.1:0.5:40, 1:0.5:2:0.05:0.2:10, and 0.5:0.99:1.56:0.02:0.1:8; the amount ratio of the biomacromolecule to the nano-reinforcing agent is 0.2g:0.1mL, 5g:3mL, 1g:2mL, and 0.5g:1.5mL.

[0036] In some embodiments of the present invention, the initially cross-linked hydrogel is obtained from the raw materials of the components described above through a polymerization reaction. Specifically, the preparation method of the initially cross-linked hydrogel includes the following steps:

[0037] After mixing biomacromolecules, first CO2-responsive monomers, second CO2-responsive monomers, deionized water, organic crosslinking agents, and nano-reinforcing agents, an initiator was added under a protective atmosphere, and polymerization was carried out at 40–70 °C to obtain an initially crosslinked hydrogel.

[0038] The mixing process involves stirring and mixing. The protective gas is nitrogen.

[0039] The polymerization reaction is carried out at a temperature of 50°C for 3 to 5 hours, for example, 5 hours or 4 hours.

[0040] In some embodiments of the present invention, the cation solution is one of calcium chloride solution, magnesium chloride solution, ferric chloride solution, ferric nitrate solution, zinc chloride solution, and zirconium acetate solution. The concentration of the cation solution is 0.05–5 mol / L, for example, 1 mol / L.

[0041] This invention also provides a method for preparing the CO2-responsive gel particles described above, comprising the following steps:

[0042] The initially cross-linked hydrogel was impregnated in a cationic solution for further cross-linking, and then dried and pulverized to obtain CO2-responsive gel particles.

[0043] The initially cross-linked hydrogel is prepared from raw materials including biomacromolecules, a first CO2-responsive monomer, a second CO2-responsive monomer, an organic cross-linking agent, a nano-reinforcing agent, an initiator, and deionized water;

[0044] The mass ratio of the biomacromolecule, the first CO2-responsive monomer, the second CO2-responsive monomer, the organic crosslinking agent, the initiator, and the deionized water is 0.1–5: 0.2–2: 0.5–5: 0.01–0.1: 0.01–0.5: 5–40; the dosage ratio of the biomacromolecule to the nano-reinforcing agent is 0.1–5 g: 0.1–1 mL.

[0045] The first CO2-responsive monomer is a self-crosslinking CO2-responsive monomer; the second CO2-responsive monomer is a non-self-crosslinking CO2-responsive monomer.

[0046] The preparation method of the initially cross-linked hydrogel is the same as above, and will not be repeated here.

[0047] In some embodiments of the present invention, the re-crosslinking temperature is room temperature and the time is 24 to 72 hours, for example, 24 hours.

[0048] In some embodiments of the present invention, the pulverization process further includes sieving.

[0049] The present invention does not impose any special restrictions on the source of the raw materials used above, and they can be commercially available.

[0050] PPG that remains stable in an acidic CO2 environment is rare, and PPG that maintains high strength in such an environment is even rarer. To ensure PPG stability in CO2, this invention introduces three CO2-responsive monomers for polymerization, imparting good temperature and salt resistance to the PPG. To enhance the strength of the PPG, this invention constructs a quadruple crosslinking network structure, including self-crosslinking of self-crosslinking CO2-responsive monomers, organic chemical crosslinking of organic crosslinking agents, nano-crosslinking of nano-reinforcing agents, and physical crosslinking of biomolecules and cationic compounds. Through monomer selection and crosslinking structure design, a high-strength PPG that remains stable in an acidic CO2 environment is finally obtained.

[0051] To further illustrate the present invention, the following detailed description of a CO2-responsive gel particle and its preparation method provided by the present invention is provided in conjunction with embodiments, but it should not be construed as limiting the scope of protection of the present invention.

[0052] In the examples, the nano-reinforcing agent was prepared according to the following method:

[0053] N-1) Under magnetic stirring, 0.0252 g of sodium dodecylbenzenesulfonate was dissolved in deionized water to obtain a 1.2 mmol / L sodium dodecylbenzenesulfonate aqueous solution; then 7.60 g of vinyltriethoxysilane was added, and after magnetic stirring for 2 h, a mixture was obtained.

[0054] N-2) Add 1 mL of ammonia water (mass concentration of ammonia water is 25% to 28%) to the mixture, stir at 50°C (400 rpm) for 24 h to obtain vinyl silica nanoparticles (VSNPs), which are nano-reinforcing agents.

[0055] The strength of PPG in this invention is mainly reflected by its elastic modulus. The larger the elastic modulus, the stronger its strength. The elastic modulus is obtained by testing the P20 / Ti rotor in a rheometer (HAAKE MARS 60).

[0056] Example 1

[0057] 1) Add 0.2g of bio-alginate sodium, 0.942g of 1-vinylimidazolium, 0.556g of N-vinylpyrrolidone, and 0.99g of N,N-dimethylacrylamide to 7.2g of deionized water, then add 0.019g of organic crosslinking agent N,N-methylenebisacrylamide and 0.1mL of nano-reinforcing agent, stir and mix well, add 0.0285g of initiator ammonium persulfate under nitrogen atmosphere, and then place in an oven at 50℃ for polymerization reaction for 4h to obtain the initially crosslinked hydrogel;

[0058] 2) The initially cross-linked hydrogel was immersed in a 0.1 mol / L room temperature calcium chloride solution for 24 h to obtain a re-cross-linked hydrogel;

[0059] 3) The re-crosslinked hydrogel is dried, pulverized, and sieved to obtain high-strength CO2-responsive gel particles.

[0060] Figure 1 This is a SEM image of the high-strength CO2-responsive gel particles in Example 1 of the present invention. Figure 1 It can be observed that the obtained CO2-responsive gel particles have a honeycomb network structure, which endows them with good water absorption and retention capabilities.

[0061] Figure 2 This is a graph showing the swelling rate of the high-strength CO2-responsive gel particles in water and saturated H2CO3 solution in Example 1 of this invention. Figure 2 It can be seen that the product's swelling rate in water is about 750%, while the swelling rate in a saturated carbonic acid solution is about 3200%, which is 4.27 times the swelling rate in water, demonstrating its excellent CO2 response characteristics.

[0062] Figure 3 This is a strength test diagram for conventional polyacrylamide gel particles. From... Figure 3 It is known that the elastic modulus of conventional polyacrylamide gel particles is approximately 10,000 Pa.

[0063] Figure 4This is a strength test diagram of the high-strength CO2-responsive gel particles in Example 1 of the present invention. From... Figure 4 It can be seen that the elastic modulus of the high-strength CO2-responsive gel particles is 78690 Pa, which is much higher than that of conventional polyacrylamide gel particles.

[0064] Testing showed that the high-strength CO2-responsive gel particles obtained in Example 1 remained stable for more than 2 months at 100°C, demonstrating excellent temperature resistance.

[0065] Example 2

[0066] 1) Add 5g of biomolecule chitosan, 0.47g of 1-vinylimidazolium, 0.56g of N-vinylpyrrolidone, and 0.49g of N-hydroxymethylacrylamide to 40g of deionized water, then add 0.1g of organic crosslinking agent hexamethylenebisacrylamide and 3mL of nano-reinforcing agent, stir and mix well, add 0.5g of initiator azobisisobutyronitrile under nitrogen atmosphere, and then place in an oven at 65℃ for polymerization reaction for 5h to obtain the initially crosslinked hydrogel;

[0067] 2) The initially cross-linked hydrogel was immersed in a 2 mol / L zinc chloride solution at room temperature for 48 h to obtain a re-cross-linked hydrogel;

[0068] 3) The re-crosslinked hydrogel is dried, pulverized, and sieved to obtain high-strength CO2-responsive gel particles.

[0069] Testing revealed that the high-strength CO2-responsive gel particles obtained in Example 2 exhibited a swelling rate of approximately 720% in water and approximately 3080% in a saturated carbonic acid solution, which is 4.28 times the swelling rate in water, demonstrating their excellent CO2-responsive characteristics. The high-strength CO2-responsive gel particles also possessed an elastic modulus of 75300 Pa, significantly higher than that of conventional polyacrylamide gel particles; they remained stable at 100°C for over two months, exhibiting excellent temperature resistance.

[0070] Example 3

[0071] 1) Add 1g of bio-macromolecule modified starch, 1g of dimethylaminoethyl methacrylate, 1g of 2-acrylamido-2-methylpropanesulfonic acid, and 0.5g of dicyclopentadienyl acrylate to 10g of deionized water, then add 0.05g of branched polyethyleneimine organic crosslinking agent and 2mL of nano-reinforcing agent, stir and mix well, add 0.2g of azobisisobutyramidine hydrochloride initiator under nitrogen atmosphere, and then place in an oven at 50℃ for polymerization reaction for 4h to obtain the initially crosslinked hydrogel;

[0072] 2) The initially cross-linked hydrogel was immersed in a 1 mol / L zinc chloride solution at room temperature for 72 h to obtain a re-cross-linked hydrogel;

[0073] 3) The re-crosslinked hydrogel is dried, pulverized, and sieved to obtain high-strength CO2-responsive gel particles.

[0074] Testing revealed that the high-strength CO2-responsive gel particles obtained in Example 3 exhibited a swelling rate of approximately 680% in water and approximately 3122% in a saturated carbonic acid solution, which is 4.59 times the swelling rate in water, demonstrating their excellent CO2-responsive characteristics. The high-strength CO2-responsive gel particles also possessed an elastic modulus of 78800 Pa, significantly higher than that of conventional polyacrylamide gel particles; they remained stable at 120°C for over one month, exhibiting excellent temperature resistance.

[0075] Example 4

[0076] 1) Add 0.5g of the biomacromolecule sodium alginate, 1g of diethylaminoethyl methacrylate, 0.56g of N,N-diethylacrylamide, and 0.99g of hydroquinone acrylate to 8g of deionized water, then add 0.02g of the organic crosslinking agent polyethyleneimine and 1.5mL of nano-reinforcing agent, stir and mix well, add 0.1g of the initiator potassium persulfate under a nitrogen atmosphere, and then place it in an oven at 60℃ for 3h to polymerize and obtain the initially crosslinked hydrogel;

[0077] 2) The initially cross-linked hydrogel was immersed in a 0.5 mol / L calcium chloride solution at room temperature for 72 h to obtain a re-cross-linked hydrogel;

[0078] 3) The re-crosslinked hydrogel is dried, pulverized, and sieved to obtain high-strength CO2-responsive gel particles.

[0079] Testing revealed that the high-strength CO2-responsive gel particles obtained in Example 4 exhibited a swelling rate of approximately 709% in water and approximately 3310% in a saturated carbonic acid solution, which is 4.67 times the swelling rate in water, demonstrating their excellent CO2-responsive characteristics. The high-strength CO2-responsive gel particles also possessed an elastic modulus of 77760 Pa, significantly higher than that of conventional polyacrylamide gel particles; they remained stable at 90°C for over 3 months, exhibiting excellent temperature resistance.

[0080] Comparative Example 1 (Comparative Example 1 does not contain a self-crosslinking CO2-responsive monomer)

[0081] The difference from Example 1 is as follows:

[0082] In step 1), all N,N-dimethylacrylamide is replaced with 1-vinylimidazole;

[0083] The remaining steps and parameters are the same as in Example 1, resulting in CO2-responsive gel particles.

[0084] Testing revealed that the high-strength CO2-responsive gel particles obtained in Comparative Example 1 exhibited a swelling rate of approximately 833% in water, and approximately 3544% in a saturated carbonic acid solution, which is 4.23 times the swelling rate in water. The high-strength CO2-responsive gel particles had an elastic modulus of 45500 Pa and remained stable at 100°C for 1.5 months.

[0085] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A CO2-responsive gel particle, which is obtained by impregnating an initially cross-linked hydrogel into a cationic solution for re-cross-linking, drying, and crushing. The initially cross-linked hydrogel is prepared from raw materials including a biological macromolecule, a first CO2-responsive monomer, a second CO2-responsive monomer, an organic cross-linking agent, a nano-enhancing agent, an initiator, and deionized water. The mass ratio of the biological macromolecule, the first CO2-responsive monomer, the second CO2-responsive monomer, the organic cross-linking agent, the initiator, and the deionized water is 0.1-5:0.2-2:0.5-5:0.01-0.1:0.01-0.5:5-40; and the usage ratio of the biological macromolecule and the nano-enhancing agent is 0.1-5 g:0.1-1 mL. The first CO2-responsive monomer is a self-cross-linking CO2-responsive monomer; and the second CO2-responsive monomer is a non-self-cross-linking CO2-responsive monomer. The first CO2-responsive monomer is at least one of N,N-dimethyl acrylamide, N-hydroxymethyl acrylamide, dicyclopentadienyl acrylate, diacetone acrylamide, and hydroquinone acrylate. The second CO2-responsive monomer is two of 2-acrylamido-2-methylpropanesulfonic acid, N-acryloyl morpholine, 1-vinylimidazole, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, N-vinyl pyrrolidone, and N,N-diethyl acrylamide. The nano-enhancing agent has a vinyl group on the surface thereof, which can undergo a cross-linking reaction. The biological macromolecule is at least one of guar gum, chitosan, gelatin, starch, sodium alginate, and hydroxymethyl cellulose.

2. The CO2-responsive gel particles according to claim 1, characterized in that, The organic cross-linking agent includes at least one of polyethyleneimine, branched polyethyleneimine, N,N-methylene bisacrylamide, ethoxylated trimethylolpropane triacrylate, and hexamethylene bisacrylamide.

3. The CO2-responsive gel particles according to claim 1, wherein The preparation method of the nano-enhancing agent includes the following steps: a) stirring and mixing a water solution of sodium dodecyl benzene sulfonate and vinyl triethoxysilane to obtain a mixed solution; b) dropping ammonia water into the stirring mixed solution, stirring and reacting to obtain vinyl silica nanoparticles, i.e., the nano-enhancing agent.

4. The CO2-responsive gel particles according to claim 1, wherein The initiator is one of ammonium persulfate, potassium persulfate, azobisisobutyronitrile, and azobisdimethylamino hexyl hydrochloride.

5. The CO2-responsive gel particle of claim 1, wherein The cationic solution is one of a calcium chloride solution, a magnesium chloride solution, a ferric chloride solution, a ferric nitrate solution, a zinc chloride solution, and a zirconium acetate solution. The concentration of the cationic solution is 0.05-5 mol / L. 6.A preparation method of the CO2-responsive gel particle according to any one of claims 1-5, which includes the following steps: impregnating an initially cross-linked hydrogel into a cationic solution for re-cross-linking, drying, and crushing to obtain a CO2-responsive gel particle; The initially cross-linked hydrogel is prepared from raw materials including a biological macromolecule, a first CO2-responsive monomer, a second CO2-responsive monomer, an organic cross-linking agent, a nano-enhancing agent, an initiator, and deionized water. The mass ratio of the biological macromolecule, the first CO2-responsive monomer, the second CO2-responsive monomer, the organic crosslinking agent, the initiator and deionized water is 0.1-5:0.2-2:0.5-5:0.01-0.1:0.01-0.5:5-40; the usage ratio of the biological macromolecule to the nano-enhancing agent is 0.1-5 g:0.1-1 mL; The first CO2-responsive monomer is a self-crosslinking type CO2-responsive monomer; and the second CO2-responsive monomer is a non-self-crosslinking type CO2-responsive monomer.

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