A quaternary thermosensitive polymer and its preparation method

Abstract

The present invention provides a quaternary thermosensitive polymer having a structural formula as shown in formula (I): wherein x, y, z, and w are the molar ratios of the polymerized units of acrylamide, N-isopropylmethacrylamide, hydroxybutyl acrylate, and β-cyclodextrin acrylate, respectively, and the ratio of x:y:z:w is 4-6:1-2:0.4-0.6:0.06-0.08. The present invention also provides a method for preparing the quaternary thermosensitive polymer.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical engineering, and particularly relates to a quaternary temperature-sensitive polymer and a preparation method thereof. Background Art

[0002] Polymer-based oil displacement agents are a new type of oil displacement agent developed in recent years, which has good use effects. However, the oil displacement performance of traditional polymer oil displacement agents is still limited. To this end, researchers have proposed the concept of intelligent chemical oil displacement, by designing and synthesizing functionalized polymer oil displacement agents that respond to the pH, temperature or external magnetic field of a specific oil field, in order to achieve the purpose of intelligently regulating fluid properties or interface properties and improving crude oil recovery. Among them, thermosensitive polymer oil displacement agents are of great significance for the development of high-temperature oil fields. The thermosensitive polymer oil displacement agents reported so far have shown great potential, but there are still many problems. For example, the ability to adjust the temperature response range is insufficient. The temperature response is mainly manifested in changing the viscosity of the displacement fluid, and the effect on reducing the oil-water interfacial tension is poor, making it difficult to reuse. Summary of the Invention

[0003] In view of this, the present invention aims to provide a quaternary thermosensitive polymer and a preparation method thereof, which can be used in oil production.

[0004] In one aspect, the present invention provides a quaternary thermosensitive polymer, the structural formula of the quaternary thermosensitive polymer is shown in formula (I):

[0005]

[0006] Wherein x, y, z and w are respectively the molar ratios of polymerized units of acrylamide, N-isopropyl methacrylamide, hydroxybutyl acrylate and β-cyclodextrin acrylate, and the x:y:z:w is 4-6:1-2:0.4-0.6:0.06-0.08.

[0007] The second aspect of the present invention provides a method for preparing a quaternary thermosensitive polymer, comprising reacting ethylene glycol monoacrylate with carbonyldiimidazole, replacing one imidazole group in the carbonyldiimidazole with a hydroxyl group in the ethylene glycol monoacrylate, and then replacing the other imidazole group with a hydroxyl group in β-cyclodextrin to obtain β-cyclodextrin acrylate. Acrylamide, N-isopropyl methacrylamide, hydroxybutyl acrylate, and β-cyclodextrin acrylate are used as polymerization monomers, and potassium persulfate and ammonium persulfate are used as initiators. A free radical polymerization reaction is initiated by heating under a nitrogen atmosphere to prepare a quaternary thermosensitive polymer.

[0008] Furthermore, the specific steps are as follows:

[0009] (1) Ethylene glycol monoacrylate and carbonyl diimidazole are stirred and reacted in tetrahydrofuran. After the reaction is completed, the mixture is dried by rotary drying. Ethyl acetate is then added to dissolve the mixture. Ultrapure water is added to wash the mixture, and the layers are separated. The organic phase is dried overnight with a desiccant and then dried by rotary drying to obtain carbonyl imidazole ethylene glycol acrylate.

[0010] (2) β-cyclodextrin and N,N-dimethylaminopyridine are dissolved in dimethyl sulfoxide to obtain solution A, carbonyl imidazole glycol acrylate prepared in step (1) is dissolved in dimethyl sulfoxide, and then added dropwise to the above solution A. After the addition is completed, the mixture is heated for reaction, and then added to an ethanol / ether mixed solvent for precipitation, filtered, washed with an ethanol / ether mixed solvent, and vacuum dried to obtain β-cyclodextrin acrylate.

[0011] (3) adding acrylamide, N-isopropylmethacrylamide, hydroxybutyl acrylate, and β-cyclodextrin acrylate prepared in step (2) into ultrapure water, stirring and dissolving at room temperature, adding potassium persulfate and ammonium persulfate to obtain a reaction solution, and after the reaction is completed, cooling the reaction solution to room temperature, then ultrafiltration and centrifugation, and freeze-drying to obtain a quaternary thermosensitive polymer.

[0012] Furthermore, in step (1), the molar ratio of ethylene glycol monoacrylate to carbonyl diimidazole is 1:1.

[0013] Furthermore, in step (1), the molar ratio of β-cyclodextrin, N,N-dimethylaminopyridine, and carbonyl imidazole glycol acrylate is 1:0.5:1, and the volume ratio of ethanol and diethyl ether in the mixed solvent is 1:1.

[0014] Furthermore, the reaction conditions in step (1) are: reaction temperature 20-30 degrees, reaction time 12-20 hours.

[0015] Furthermore, the desiccant in step (1) is any one of anhydrous magnesium sulfate, anhydrous sodium sulfate and molecular sieve.

[0016] Furthermore, the reaction conditions in step (2) are: reaction temperature 55-65° C., reaction time 12-24 hours.

[0017] Furthermore, the reaction conditions in step (3) are as follows: first, the reaction solution is bubbled with nitrogen for 1-2 hours, and then the reaction solution is heated to 70-80° C. under stirring conditions for reaction.

[0018] Furthermore, in step (3), the molar ratio of acrylamide, N-isopropylmethacrylamide, hydroxybutyl acrylate, and β-cyclodextrin acrylate is 3-4:1-2:1:0.2.

[0019] Furthermore, the total amount of the potassium persulfate and ammonium persulfate is 0.05% to 0.15% of the total mass of the polymerized monomers, and the mass ratio of the potassium persulfate to the ammonium persulfate is 1:1.

[0020] Beneficial effects:

[0021] The present invention provides a quaternary thermosensitive polymer. Self-made β-cyclodextrin acrylate is added as one of the polymerization units, and the hydrophilicity and lipophilicity are more balanced. The quaternary thermosensitive polymer generates host-guest interaction with N-isopropyl and hydroxybutyl groups that undergo phase change through a cavity to form a network structure, thereby significantly increasing the viscosity of the solution. By adjusting the composition ratio with the other three polymerization units (acrylamide, N-isopropylmethacrylamide, and hydroxybutyl acrylate), a quaternary thermosensitive polymer with different temperature responses can be obtained. When the temperature rises to above the lower critical solution temperature, the polymer solution has a significant thickening effect, and the interfacial tension between the polymer solution and the oil phase is reduced. When the temperature drops below the lower critical solution temperature, the polymer solution and the oil phase can be effectively separated. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The structures, proportions, sizes, etc. illustrated in this specification are intended only to complement the contents disclosed herein and to facilitate understanding and reading by persons familiar with the art. They are not intended to limit the conditions under which the present invention may be implemented and therefore have no substantive technical significance. Any structural modifications, changes in proportions, or adjustments in sizes, without affecting the efficacy and objectives of the present invention, shall still fall within the scope of the technical contents disclosed herein.

[0023] Figure 1 This is a hydrogen nuclear magnetic resonance spectrum of poly(acrylamide-N-isopropylmethacrylamide-hydroxybutyl acrylate-β-cyclodextrin acrylate) prepared in Example 2 of the present invention in deuterated water. DETAILED DESCRIPTION

[0024] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the examples in the specification. Unless otherwise specified, the methods described are all conventional methods, and the raw materials described can be obtained from public commercial channels unless otherwise specified.

[0025] As used herein, "one embodiment" or "embodiment" refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, nor does it necessarily refer to a separate or selective embodiment that is mutually exclusive of other embodiments.

[0026] The present invention provides an embodiment of a quaternary thermosensitive polymer, the structural formula of the quaternary thermosensitive polymer is shown in formula (I):

[0027]

[0028] Wherein x, y, z and w are respectively the molar ratios of polymerized units of acrylamide, N-isopropyl methacrylamide, hydroxybutyl acrylate and β-cyclodextrin acrylate, and the x:y:z:w is 4-6:1-2:0.4-0.6:0.06-0.08.

[0029] The above polymer is prepared by the following method:

[0030] (1) Ethylene glycol monoacrylate and carbonyl diimidazole are stirred and reacted in tetrahydrofuran. After the reaction is completed, the mixture is dried by rotary drying. Ethyl acetate is then added to dissolve the mixture. Ultrapure water is added to wash the mixture, and the layers are separated. The organic phase is dried overnight with a desiccant and then dried by rotary drying to obtain carbonyl imidazole ethylene glycol acrylate.

[0031] (2) β-cyclodextrin and N,N-dimethylaminopyridine are dissolved in dimethyl sulfoxide to obtain solution A, carbonyl imidazole glycol acrylate prepared in step (1) is dissolved in dimethyl sulfoxide, and then added dropwise to the above solution A. After the addition is completed, the mixture is heated for reaction, and then added to an ethanol / ether mixed solvent for precipitation, filtered, washed with an ethanol / ether mixed solvent, and vacuum dried to obtain β-cyclodextrin acrylate.

[0032] (3) adding acrylamide, N-isopropylmethacrylamide, hydroxybutyl acrylate, and β-cyclodextrin acrylate prepared in step (2) into ultrapure water, stirring and dissolving at room temperature, adding potassium persulfate and ammonium persulfate to obtain a reaction solution, and after the reaction is completed, cooling the reaction solution to room temperature, then ultrafiltration and centrifugation, and freeze-drying to obtain a quaternary thermosensitive polymer.

[0033] Preferably, in the step (1), the molar ratio of β-cyclodextrin, N,N-dimethylaminopyridine, and carbonyl imidazole glycol acrylate is 1:0.5:1, the volume ratio of ethanol and ether in the mixed solvent is 1:1, the reaction temperature is 20-30 degrees, the reaction time is 12-20 hours, and the desiccant is any one of anhydrous magnesium sulfate, anhydrous sodium sulfate, and molecular sieves; the reaction conditions in the step (2) are: reaction temperature 55-65°C, reaction time 12-24 hours; The reaction conditions in step (3) are as follows: first, the reaction solution is bubbled with nitrogen for 1-2 hours, and then the reaction solution is heated to 70-80°C under stirring for reaction, the molar ratio of acrylamide, N-isopropylmethacrylamide, hydroxybutyl acrylate, and β-cyclodextrin acrylate is 3-4:1-2:1:0.2; the total amount of potassium persulfate and ammonium persulfate is 0.05%-0.15% of the total mass of the polymerized monomers, and the mass ratio of potassium persulfate to ammonium persulfate is 1:1.

[0034] Example 1

[0035] Preparation of β-cyclodextrin acrylate

[0036] (1) Ethylene glycol monoacrylate (1.16 g) and carbonyl diimidazole (1.62 g) were stirred in 50 mL of tetrahydrofuran at room temperature for 24 hours, and then dried by rotary evaporation. 40 mL of ethyl acetate was then added for dissolution, and the mixture was extracted three times with 20 mL of ultrapure water. The organic phase was dried over magnesium sulfate overnight and dried by rotary evaporation to obtain carbonyl imidazole ethylene glycol acrylate (molar yield 78%).

[0037] (2) β-cyclodextrin (1.13 g) and N,N-dimethylaminopyridine (0.06 g) were dissolved in 10 mL of dimethyl sulfoxide, and carbonyl imidazole glycol acrylate (0.21 g) was dissolved in 5 mL of dimethyl sulfoxide, and then added dropwise to the above solution. After the addition was completed, it was heated to 60 ° C and reacted for 12 hours. Then, it was added to 100 mL of ethanol / ether mixed solvent (1:1) for precipitation, filtered, washed with ethanol / ether mixed solvent, and vacuum dried to obtain β-cyclodextrin acrylate (molar yield 72%).

[0038] Example 2

[0039] Preparation of Quaternary Thermosensitive Polymers

[0040] (3) 1.42 g of acrylamide, 0.635 g of N-isopropylmethacrylamide, 0.72 g of hydroxybutyl acrylate, and 1.277 g of β-cyclodextrin acrylate prepared in Example 1 were added to a three-necked flask, 50 mL of ultrapure water was added, and the mixture was stirred at room temperature for dissolution. 2 mg of potassium persulfate and 2 mg of ammonium persulfate were added, and nitrogen was bubbled through for 1 hour. The reaction solution was heated to 80° C. under a nitrogen atmosphere and stirred for 12 hours. The reaction solution was then cooled to room temperature, ultrafiltered and centrifuged (10,000 rpm, 10 minutes, molecular weight cut-off 14,000), and freeze-dried to obtain a white solid. The weight-average molecular weight of the polymer was 238,724, and the polydispersity index was 1.2 as measured by gel permeation chromatography.

[0041] The prepared copolymers were characterized by H NMR spectroscopy. Figure 1 .according to Figure 1 The integral ratios of the characteristic methylene signal (4 ppm) in the polymer unit hydroxybutyl acrylate, the characteristic methyl signal (1 ppm) in N-isopropylmethylacrylamide, the characteristic β-cyclodextrin signal (3.5 ppm) in β-cyclodextrin acrylate, and the backbone hydrogen signals (1.8-2.5 ppm) of each polymer unit were used to calculate the molar ratio of acrylamide, N-isopropylmethacrylamide, hydroxybutyl acrylate, and β-cyclodextrin acrylate in the polymer to be 5.7:1:0.5:0.07.

[0042] Example 3

[0043] Preparation of Quaternary Thermosensitive Polymers

[0044] 1.065 g of acrylamide, 0.635 g of N-isopropylmethacrylamide, 0.72 g of hydroxybutyl acrylate, and 1.277 g of β-cyclodextrin acrylate prepared in Example 1 were added to a three-necked flask, 50 mL of ultrapure water was added and stirred at room temperature for dissolution, 2 mg of potassium persulfate and 2 mg of ammonium persulfate were added, and nitrogen was bubbled into the flask for 1 hour. The reaction solution was heated to 75° C. under a nitrogen atmosphere and stirred for 8 hours. The reaction solution was then cooled to room temperature, ultrafiltered and centrifuged (10,000 rpm, 10 minutes, molecular weight cutoff 14,000), and freeze-dried to obtain a white solid.

[0045] The weight-average molecular weight of the polymer was measured by gel permeation chromatography to be 183615, and the polynomial index was 1.4. The molar ratio of acrylamide, N-isopropylmethacrylamide, hydroxybutyl acrylate, and β-cyclodextrin acrylate in the polymer was calculated by nuclear magnetic resonance to be 4.4:1:0.47:0.06.

[0046] Example 4

[0047] Preparation of Quaternary Thermosensitive Polymers

[0048] 1.42g acrylamide, 1.27g N-isopropylmethacrylamide, 0.72g hydroxybutyl acrylate, 1.277g embodiment 1 acrylic acid beta-cyclodextrin ester are added in there-necked flask, 50mL ultrapure water stirring at room temperature is added to dissolve, 2mg potassium persulfate and 2mg ammonium persulfate are added, bubbling method is passed into nitrogen 1 hour, under nitrogen atmosphere, reaction solution is heated to 75 DEG C, stirring reaction 8 hours, then reaction solution is cooled to room temperature, ultrafiltration centrifugation (10000 rev / min, 10 minutes, molecular weight cut-off 14000), lyophilization obtains white solid.It is 214483 that recording polymer weight-average molecular weight by gel permeation chromatography, and multi-fraction index is 1.3, and the mol ratio of acrylamide, N-isopropylmethacrylamide, hydroxybutyl acrylate, acrylic acid beta-cyclodextrin ester obtained by nuclear magnetic resonance calculation in polymer is 5.1:2:0.52:0.08.

[0049] Comparative Example 1

[0050] Preparation of poly (acrylamide-N-isopropylmethacrylamide-hydroxybutyl acrylate)

[0051] 1.42 g acrylamide, 0.635 g N-isopropylmethacrylamide, and 0.72 g hydroxybutyl acrylate were added to a three-necked flask, 50 mL of ultrapure water was added and stirred at room temperature for dissolution, 2 mg of potassium persulfate and 2 mg of ammonium persulfate were added, nitrogen was bubbled through for 1 hour, the reaction solution was heated to 75 ° C under a nitrogen atmosphere, and the stirring reaction was performed for 8 hours. The reaction solution was then cooled to room temperature and ultrafiltration centrifuged (10,000 rpm, 10 minutes, molecular weight cut-off 14,000), and freeze-dried to obtain a white solid. The polymer weight-average molecular weight measured by gel permeation chromatography was 245,817, the multiplicity index was 1.2, and the molar ratio of acrylamide, N-isopropylmethacrylamide, and hydroxybutyl acrylate in the polymer was calculated by nuclear magnetic resonance to be 5.8:1:0.56.

[0052] Experimental Example 1

[0053] Viscosity test of 2% polymer aqueous solution

[0054] Preparation of 2% polymer solution: The quaternary thermosensitive polymer prepared in Examples 2 to 4 and the poly (acrylamide-N-isopropylmethacrylamide-hydroxybutyl acrylate) prepared in Comparative Example 1 were added to a beaker respectively, and ultrapure water was added. The mixture was stirred at room temperature to dissolve to prepare a polymer solution with a mass concentration of 2%.

[0055] Viscosity test: The viscosity of the 2% polymer solution prepared above was measured using a fully automatic rotational viscometer at different temperatures and a shear rate of 100s. -1 .

[0056] As shown in Table 1, the quaternary thermosensitive polymers prepared in Examples 2 to 4 have different temperature responsiveness. The viscosity of the polymer prepared in Example 2 increases significantly when the temperature reaches 70°C, the viscosity of the polymer prepared in Example 3 increases significantly when the temperature reaches 60°C, and the viscosity of the polymer prepared in Example 4 increases significantly when the temperature reaches 50°C. This indicates that by adjusting the ratio of the polymer units in the quaternary thermosensitive polymers, polymers with different temperature responsiveness can be prepared. Among them, the quaternary thermosensitive polymer prepared in Example 2 has the highest viscosity and the highest response temperature, the quaternary thermosensitive polymer prepared in Example 3 has the second highest viscosity and a lower response temperature than that of Example 2, and the quaternary thermosensitive polymer prepared in Example 4 has the lowest viscosity and the lowest response temperature. The poly(acrylamide-N-isopropylmethacrylamide-hydroxybutyl acrylate) prepared in Comparative Example 1 has a viscosity that decreases with increasing temperature within the test temperature range and is not temperature-responsive, indicating that the polymerized unit β-cyclodextrin acrylate introduced in Examples 2 to 4 plays an important role in temperature responsiveness. It is speculated that this is because it produces a host-guest interaction with the N-isopropyl and hydroxybutyl groups that undergo phase change through the cavity, forming a network structure, thereby significantly increasing the viscosity of the solution.

[0057] Table 1. Viscosity of 2% polymer solution (mPa·s) as a function of temperature

[0058]

[0059] Experimental Example 2

[0060] Oil-water interfacial tension measurement

[0061] 0# diesel was mixed with the 2% polymer solution prepared in Experimental Example 1 at a volume ratio of 1:1 to prepare an oil-water mixed solution. The interfacial tension between the polymer aqueous solution and ultrapure water at 20°C and 70°C was measured using a fully automatic interfacial tension meter.

[0062] As shown in Table 2, the polymers prepared in Examples 2 to 4 and Comparative Example 1 all have certain surface activity, and the surface activity of Comparative Example 1 is the highest. At a high temperature of 70°C, the surface activity of the polymers prepared in Examples 2 to 4 and Comparative Example 1 is significantly enhanced, mainly because the N-isopropyl and hydroxybutyl groups in the side chains of the quaternary thermosensitive polymer undergo a phase change at high temperature, changing from hydrophilic to hydrophobic, thereby increasing the surface activity. Among them, the surface activity of the polymers prepared in Examples 2 to 4 is stronger than that of the polymer prepared in Comparative Example 1, because the introduction of the polymerization unit acrylic acid β-cyclodextrin makes the hydrophilic and lipophilic properties of the polymer more balanced.

[0063] Table 2. Changes in oil-water interfacial tension (mN / m) with temperature

[0064]

[0065] Experimental Example 3

[0066] Oil-water separation experiment

[0067] A mixed solution was prepared by mixing 0# diesel and the 2% polymer solution prepared in Experimental Example 1 in a volume ratio of 1:1. The mixed solution was placed in a graduated cylinder with a stopper and kept at a constant temperature of 70°C for 30 minutes. The mixture was taken out and shaken 150 times, and then naturally cooled to room temperature. The volume of the aqueous phase was read and the proportion of the aqueous phase volume to the total volume was calculated.

[0068] As shown in Table 3, in the experiments conducted using the quaternary thermosensitive polymers prepared in Examples 2 to 4, the polymer prepared in Example 2 had the highest degree of oil-water separation after high-temperature emulsification and cooling to room temperature, followed by Example 3, and the lowest degree of oil-water separation in Example 4. However, the oil-water separation degree of the quaternary thermosensitive polymers prepared in Examples 2 to 4 was higher than that of the poly(acrylamide-N-isopropylmethacrylamide-hydroxybutyl acrylate) prepared in Comparative Example 1. This is because the quaternary thermosensitive polymers prepared in Examples 2 to 4 introduced the polymerized unit of acrylic acid β-cyclodextrin, which makes them more hydrophilic at low temperatures and less surface active, which is conducive to oil-water separation at low temperatures. This also makes the polymers prepared in Examples 1 to 3 have better recyclability.

[0069] Table 3. Water phase volume ratio

[0070]

[0071] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A quaternary thermosensitive polymer, characterized in that: The structural formula of the quaternary thermosensitive polymer is shown in formula (I): Wherein x, y, z and w are respectively the molar ratios of polymerized units of acrylamide, N-isopropyl methacrylamide, hydroxybutyl acrylate and β-cyclodextrin acrylate, and the x:y:z:w is 4-6:1-2:0.4-0.6:0.06-0.

08.

2. A method for preparing a quaternary thermosensitive polymer according to claim 1, characterized in that: The specific steps are as follows: (1) Ethylene glycol monoacrylate and carbonyl diimidazole are stirred and reacted in tetrahydrofuran. After the reaction is completed, the mixture is dried by spin drying. Ethyl acetate is then added to dissolve the mixture. Ultrapure water is added to wash the mixture, and the layers are separated. The organic phase is dried overnight with a desiccant and then dried by spin drying to obtain carbonyl imidazole ethylene glycol acrylate. (2) dissolving β-cyclodextrin and N,N-dimethylaminopyridine in dimethyl sulfoxide to obtain solution A, dissolving the carbonyl imidazole glycol acrylate prepared in step (1) in dimethyl sulfoxide, and then adding dropwise to the above solution A, heating to react after the dropwise addition is completed, and then adding to an ethanol / ether mixed solvent, filtering, washing with the ethanol / ether mixed solvent, and vacuum drying to obtain β-cyclodextrin acrylate; (3) adding acrylamide, N-isopropylmethacrylamide, hydroxybutyl acrylate and β-cyclodextrin acrylate prepared in step (2) into ultrapure water, stirring and dissolving at room temperature, adding potassium persulfate and ammonium persulfate to obtain a reaction solution, and after the reaction is completed, cooling the reaction solution to room temperature, then ultrafiltration and centrifugation, and freeze-drying to obtain a quaternary thermosensitive polymer.

3. The method for preparing a quaternary thermosensitive polymer according to claim 2, wherein: The molar ratio of ethylene glycol monoacrylate to carbonyl diimidazole in step (1) is 1:

1.

4. The method for preparing a quaternary thermosensitive polymer according to claim 2, wherein: In the step (2), the molar ratio of β-cyclodextrin, N,N-dimethylaminopyridine, and carbonyl imidazole glycol acrylate is 1:0.5:1, and the volume ratio of ethanol and ether in the mixed solvent is 1:

1.

5. The method for preparing a quaternary thermosensitive polymer according to claim 2, wherein: The reaction conditions in step (1) are: reaction temperature 20-30 degrees, reaction time 12-20 hours.

6. The method for preparing a quaternary thermosensitive polymer according to claim 2, wherein: The desiccant in step (1) is any one of anhydrous magnesium sulfate, anhydrous sodium sulfate and molecular sieve.

7. The method for preparing a quaternary thermosensitive polymer according to claim 2, wherein: The reaction conditions in step (2) are: reaction temperature 55-65° C., reaction time 12-24 hours.

8. The method for preparing a quaternary thermosensitive polymer according to claim 2, wherein: The reaction conditions in step (3) are as follows: first, the reaction solution is bubbled with nitrogen for 1-2 hours, and then the reaction solution is heated to 70-80° C. under stirring conditions for reaction.

9. The method for preparing a quaternary thermosensitive polymer according to claim 2, wherein: In the step (3), the molar ratio of acrylamide, N-isopropylmethacrylamide, hydroxybutyl acrylate, and β-cyclodextrin acrylate is 3-4:1-2:1:0.

2.

10. The method for preparing a quaternary thermosensitive polymer according to claim 2, wherein: The total amount of the potassium persulfate and ammonium persulfate is 0.05% to 0.15% of the total mass of the polymerized monomers, and the mass ratio of the potassium persulfate to the ammonium persulfate is 1:1.

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