A modified aminopolysiloxane polymer, preparation method and application thereof

Abstract

The invention relates to the technical field of petroleum materials, and discloses a modified aminopolysiloxane polymer, a preparation method and an application thereof. The modified aminopolysiloxane polymer comprises the following steps: step 1: adding methoxy polyethylene glycol acrylate to a maleic anhydride solution under an inert gas atmosphere, adding an initiator, fully reacting, and purifying to obtain a maleic anhydride and methoxy polyethylene glycol acrylate copolymer; step 2: adding a catalyst to the copolymer solution obtained in step 1 under an inert gas atmosphere, dripping an aminopolysiloxane solution, fully reacting, and purifying to obtain a desired modified aminopolysiloxane polymer; the modified aminopolysiloxane polymer obtained by the invention can also form a spatial network structure under the cooperation of an auxiliary agent, so as to achieve the purpose of increasing the viscosity of supercritical carbon dioxide, and does not contain fluorine compounds in the preparation process, and avoids conventional precious metal catalysts and hazardous chemicals.

Description

Technical Field

[0001] The invention relates to the technical field of petroleum extraction, and in particular to a modified aminopolysiloxane polymer, a preparation method and application thereof. Background Art

[0002] At present, supercritical carbon dioxide thickeners most commonly use fluorine-containing compounds or polymers. Such substances have high biological toxicity and cause great damage to the formation, especially contaminating groundwater resources, which leads to serious environmental damage. In addition, fluorine-containing substances are expensive and economically unfeasible. The existing patent publication number is CN114920899 A, which reports "a highly efficient tackifying liquid carbon dioxide thickener and its preparation method". Although the thickening effect is good, it involves the presence of fluorine elements, which to a certain extent hinders its practical application in fracturing and oil recovery in oil fields. In addition, hydrocarbon polymers are also used as carbon dioxide thickeners, but the thickening effect is not ideal, and the long duration of subsequent degradation is also always in urgent need of facing.

[0003] At present, there are also research reports on fluorine-free supercritical carbon dioxide thickeners, such as patent application number CN201711162131X and publication number CN 114920899 A, which disclose the preparation method of supercritical carbon dioxide thickener containing siloxane polymer. Although the raw materials of the reported supercritical carbon dioxide thickener do not contain fluorine compounds, the preparation process uses precious metal chloroplatinic acid as a catalyst, resulting in a high cost of product preparation, which limits its application in oil and gas field fracturing and oil recovery. Summary of the invention

[0004] The present invention aims to solve the problems existing in the prior art and provides a modified aminopolysiloxane polymer, a preparation method and an application thereof.

[0005] The technical solution adopted by the present invention is: a method for preparing a modified aminopolysiloxane polymer, comprising the following steps:

[0006] Step 1: under an inert gas atmosphere, methoxy polyethylene glycol acrylate is added to a maleic anhydride solution, and then an initiator is added dropwise, reacted sufficiently, and purified to obtain a copolymer of maleic anhydride and methoxy polyethylene glycol acrylate; the molar ratio of maleic anhydride to methoxy polyethylene glycol acrylate is 1:2-10;

[0007] Step 2: Under an inert gas atmosphere, a catalyst is added to the copolymer solution obtained in step 1, and aminopolysiloxane is added dropwise. After sufficient reaction, the desired modified aminopolysiloxane polymer can be obtained after purification; the mass ratio of the copolymer to the aminopolysiloxane is 1:1 to 3.5.

[0008] Furthermore, in step 1, the initiator is one or a mixture of two or more of benzoyl peroxide, azobisisobutyronitrile, and azobisisoheptylnitrile in any proportion; wherein the added amount of the initiator is 0.5 wt.% to 1.5 wt.% of the total mass of maleic anhydride and methoxy polyethylene glycol acrylate.

[0009] Furthermore, the reaction temperature in step 1 is 70-85° C., and the reaction time is 3-8 hours.

[0010] Furthermore, in step 2, the aminopolysiloxane is a side chain aminopolysiloxane, and the side chain amino group is one of aminopropyl, N-(β-aminoethyliminoethyl)-γ-aminopropyl, and N-β-aminoethyl-γ-aminopropyl, preferably N-β-aminoethyl-γ-aminopropyl.

[0011] Furthermore, the catalyst is one or two of hydrochloric acid, phosphoric acid, formic acid, acetic acid, and oxalic acid mixed in any proportion, and the added amount of the catalyst accounts for 0.1 wt.% to 1.2 wt.% of the mass of the copolymer.

[0012] Furthermore, the reaction temperature in step 2 is 75-90° C., and the reaction time is 3-8 hours.

[0013] Furthermore, the reaction solvent in step 1 and step 2 is toluene; after the reaction in step 1 and step 2 is completed, impurities are removed by reduced pressure distillation.

[0014] A modified aminopolysiloxane polymer having the following structure:

[0015]

[0016] An application of a modified aminopolysiloxane polymer, wherein the modified aminopolysiloxane is used as a supercritical carbon dioxide thickener.

[0017] Furthermore, the modified aminopolysiloxane is added with an auxiliary agent to obtain a supercritical carbon dioxide thickener with a mass concentration of 1 wt.% to 2.5 wt.%.

[0018] The beneficial effects of the present invention are:

[0019] (1) The present invention uses maleic anhydride monomer as a bridge for synthesizing modified aminopolysiloxane. On the one hand, specific functional groups can be flexibly introduced; on the other hand, maleic anhydride and aminopolysiloxane undergo amidation reaction, the molecular weight and ammonia content of aminopolysiloxane are adjustable, the performance parameters of the synthesized material are controllable, the reaction principle is simple, the time is short, and the efficiency is high;

[0020] (2) The modified aminopolysiloxane polymer obtained by the present invention is directly used as a supercritical carbon dioxide thickener, and can also form a spatial network structure with the help of an auxiliary agent to achieve the purpose of increasing the viscosity of supercritical carbon dioxide;

[0021] (3) The raw materials of the present invention do not contain fluorine polymers, avoid the use of conventional precious metal catalysts and other hazardous chemicals, and have a good thickening effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is the infrared spectrum of the modified aminopolysiloxane polymer intermediate obtained in Example 1 of the present invention.

[0023] Figure 2 This is the infrared spectrum of the synthetic product of the modified aminopolysiloxane polymer obtained in Example 1 of the present invention.

[0024] Figure 3 This is the shear test result of the modified aminopolysiloxane polymer obtained in Example 1 of the present invention as a thickener. DETAILED DESCRIPTION

[0025] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0026] A method for preparing a modified aminopolysiloxane polymer comprises the following steps:

[0027] Step 1: Under an inert gas atmosphere, maleic anhydride monomer is added toluene, and stirred at 50-60°C for 0.5-1.5 hours to fully dissolve; methoxy polyethylene glycol acrylate is added to the maleic anhydride solution, and an initiator is added dropwise; reflux polymerization is carried out; and then toluene and other low-boiling point substances are removed by vacuum distillation to obtain a copolymer of maleic anhydride and methoxy polyethylene glycol acrylate; the molar ratio of maleic anhydride to methoxy polyethylene glycol acrylate is 1:2-10.

[0028] Maleic anhydride can also be a homologue substituted with different alkyl groups. The initiator is a mixture of one or more of benzoyl peroxide and azobisisoheptanenitrile in any proportion; the amount of the initiator added is 0.5 wt.% to 1.5 wt.% of the total mass of maleic anhydride and methoxy polyethylene glycol acrylate, and the initiator is added dropwise within 0.5 to 1 hour.

[0029] After adding methoxy polyethylene glycol acrylate to the maleic anhydride solution, the solvent in the solution accounts for 60wt.% to 75wt.% of the total mass. The polymerization reaction is carried out at a reaction temperature of 75 to 90°C and a reaction time of 3 to 8 hours. The reaction is heated for 1.5 to 3 hours at a vacuum degree of 0.01 to 0.05 MPa and a temperature of 90 to 120°C.

[0030] Step 2: Under an inert gas atmosphere, the copolymer obtained in step 1 is dissolved in toluene, heated and dissolved, and then an acidic catalyst is added dropwise; subsequently, a toluene solution containing aminopolysiloxane is added dropwise to cause an amidation reaction, and after low-boiling substances are distilled from the reactants, a modified aminopolysiloxane polymer is obtained; the mass ratio of the copolymer to the aminopolysiloxane is 1:1 to 3.5; the amidation reaction temperature is 75 to 90°C, and the reaction time is 3 to 8 hours.

[0031] The aminopolysiloxane is a side chain aminopolysiloxane, and the side chain group is one of aminopropyl, N-(β-aminoethyliminoethyl)-γ-aminopropyl, and N-β-aminoethyl-γ-aminopropyl. The catalyst is one of hydrochloric acid, phosphoric acid, formic acid, acetic acid, and oxalic acid, or two of them mixed in any proportion to form the catalyst, and the added amount accounts for 0.1 wt.% to 1.2 wt.% of the mass of the copolymer, and the catalyst is added dropwise within 0.5 to 1 hour.

[0032] In the copolymer solution, toluene accounts for 50 wt.% to 75 wt.% of the mass of the reaction system; the copolymer is stirred at 50 to 70 °C for 0.5 to 1 h, and then the catalyst is added. The mass ratio of the solute aminopolysiloxane to the solvent toluene is 1:1 to 2.5. The conditions for distilling off low boiling substances are: vacuum degree 0.02 to 0.06 MPa, heating at 90 to 115 °C for 1.5 to 3 h.

[0033] In the above reactions, the inert gas is nitrogen.

[0034] The modified aminosiloxane polymer obtained in step 2 is added with an auxiliary agent to prepare a solution with a mass concentration of 1 wt.% to 2.5 wt.% as a supercritical carbon dioxide thickener; the fracturing performance of dense oil and gas layers can be enhanced, and the sand carrying performance can be directly enhanced.

[0035] Example 1

[0036] A method for preparing a modified aminopolysiloxane polymer comprises the following steps:

[0037] Step 1: Under nitrogen protection, add 2.5 g of maleic anhydride and 147.5 g of toluene solvent to a 500 mL dry three-necked flask, heat to 50 °C, stir for 1 hour after the maleic anhydride is dissolved, then add 50 g of methoxy polyethylene glycol acrylate; heat to 80 °C, drop 10 g of toluene solvent containing 0.525 g of azobisisoheptanenitrile, dropwise add, complete the dropwise addition in 1 hour, stir and react for 8 hours, and cool to room temperature. Vacuum 0.05 MPa, temperature 90 °C for 2 hours, remove low boiling points, and obtain a copolymer of maleic anhydride and methoxy polyethylene glycol acrylate.

[0038] The infrared spectrum of maleic anhydride and methoxy polyethylene glycol acrylate copolymer is shown in Figure 1 Shown: 2874cm -1 The stretching vibration characteristic peak of polyoxyethylene CH is 1731 cm -1 The peak at 1107cm is the characteristic peak of the ester C=O stretching vibration. -1 The peak is the characteristic peak of ether bond CO stretching vibration.

[0039] Step 2: Under nitrogen protection, add 10 g of maleic anhydride and methoxy polyethylene glycol acrylate copolymer and 80 g of toluene to a 250 mL dry three-necked flask, heat to 60°C until all are dissolved, and stir for 1 hour. Then add 0.1 g of glacial acetic acid, heat to 85°C, and drop 50 g of toluene solution containing 25 g of N-β-aminoethyl-γ-aminopropyl polydimethylsiloxane within 1 hour. After reacting for 8 hours, heat to 100°C and continue heating for 2 hours to remove low-boiling substances to obtain a viscous substance, which is the modified aminosiloxane polymer.

[0040] Infrared spectrum Figure 2 As shown in the figure, it can be seen that 3465-3468cm -1 The characteristic peak of carboxylic acid OH stretching vibration is 2877cm -1 The stretching vibration characteristic peak of polyoxyethylene CH is 1731 cm -1 The peak at 1107cm is the characteristic peak of the ester C=O stretching vibration. -1 It is the characteristic peak of ether bond CO stretching vibration.

[0041] Example 2

[0042] A method for preparing a modified aminopolysiloxane polymer comprises the following steps:

[0043] Step 1: Under nitrogen protection, add 2.5 g maleic anhydride MA and 57.5 g toluene solvent to a 250 mL dry three-necked flask, heat to 60 ° C, stir for 0.5 hours after the maleic anhydride is dissolved, and then add 20 g methoxy polyethylene glycol acrylate; heat to 85 ° C, add 10 g toluene solvent containing 0.225 g benzoyl peroxide, and add it dropwise for 0.5 hours. Then stir and react at 85 ° C for 6 hours and cool to room temperature. Heat at 120 ° C for 1.5 hours under vacuum degree of 0.01 MPa to remove low boiling points to obtain a copolymer of maleic anhydride and methoxy polyethylene glycol acrylate.

[0044] Step 2: Under nitrogen protection, add 10 g of maleic anhydride and methoxy polyethylene glycol acrylate copolymer and 80 g of toluene to a 250 mL dry three-necked flask, heat to 50 °C until all dissolved, and stir for 0.5 h. Then add 0.1 g of hydrochloric acid, heat to 90 °C, and drop 70 g of toluene solution containing 35 g of N-β-aminoethyl-γ-aminopropyl polydimethylsiloxane. The addition is completed within 0.5 h and the reaction is carried out for 6 h. Stop the reaction and cool to room temperature. Heat for 1.5 h under vacuum of 0.02 MPa and temperature of 110 °C to remove low-boiling substances to obtain a viscous substance, which is a modified aminosiloxane polymer.

[0045] Example 3

[0046] A method for preparing a modified aminopolysiloxane polymer comprises the following steps:

[0047] Step 1: Under nitrogen protection, add 2.5 g maleic anhydride MA and 72.5 g toluene solvent to a 250 mL dry three-necked flask, heat to 70 °C, stir for 1.5 hours after the maleic anhydride is dissolved, and then add 25 g methoxy polyethylene glycol acrylate; heat to 70 °C, add 10 g toluene solvent containing 0.275 g benzoyl peroxide dropwise, and the addition is completed in 0.8 h. Then stir the reaction at 70 °C for 3 h and cool to room temperature. Heat at 90 °C for 3 h under vacuum degree of 0.03 MPa to remove low boiling substances to obtain a copolymer of maleic anhydride and methoxy polyethylene glycol acrylate.

[0048] Step 2: Under nitrogen protection, add 10 g of maleic anhydride and methoxy polyethylene glycol acrylate copolymer and 80 g of toluene to a 250 mL dry three-necked flask, heat to 70 °C until all are dissolved, and stir for 1 h. Then add 0.1 g of phosphoric acid, heat to 75 °C, and drop 20 g of toluene solution containing 10 g of N-β-aminoethyl-γ-aminopropyl polydimethylsiloxane. The addition is completed within 0.8 h and the reaction is continued for 3 h. Stop the reaction and cool to room temperature, heat for 3 h under vacuum of 0.06 MPa and 90 °C, remove low-boiling substances under reduced pressure, and obtain a viscous substance, which is the modified aminosiloxane polymer.

[0049] Example 4

[0050] A method for preparing a modified aminopolysiloxane polymer comprises the following steps:

[0051] Step 1: Under nitrogen protection, add 2.5 g of maleic anhydride and 126.5 g of toluene solvent to a 250 mL dry three-necked flask, heat to 50 °C, stir for 1 hour after the maleic anhydride is dissolved, and then add 40 g of methoxy polyethylene glycol acrylate; heat to 80 °C, add 10 g of toluene solvent containing 0.425 g of azobisisoheptanenitrile dropwise, and the addition is completed within 1 hour. Then stir the reaction at 80 °C for 8 hours and cool to room temperature. Heat at 110 °C for 2 hours under vacuum degree of 0.05 MPa to remove low boiling substances to obtain a copolymer of maleic anhydride and methoxy polyethylene glycol acrylate.

[0052] Step 2: Under nitrogen protection, add 10 g of maleic anhydride and methoxy polyethylene glycol acrylate copolymer and 80 g of toluene to a 250 mL dry three-necked flask, heat to 60°C until it is completely dissolved, and stir for 1 h. Then add 0.1 g of glacial acetic acid and heat to 75°C, and drop 50 g of toluene solution containing 15 g of N-β-aminoethyl-γ-aminopropyl polydimethylsiloxane. The addition is completed within 1 h and the reaction is continued for 6.5 h. Stop the reaction and cool to room temperature, heat for 2 h under vacuum of 0.04 MPa and temperature of 100°C, remove low-boiling substances, and obtain a viscous substance, which is the modified aminosiloxane polymer.

[0053] Example 5

[0054] Step 1: Under nitrogen protection, add 2.5 g of maleic anhydride and 290 g of toluene solvent to a 1000 mL dry three-necked flask, heat to 50 ° C, stir for 1 hour after the maleic anhydride is dissolved, and then add 100 g of methoxy polyethylene glycol acrylate; heat to 80 ° C, add 20 g of toluene solvent containing 2.025 g of azobisisoheptanenitrile dropwise, and the addition is completed in 2 hours. Then stir the reaction at 80 ° C for 8 hours and cool to room temperature. Heat at a vacuum degree of 0.05 MPa and a temperature of 110 ° C for 2 hours to remove low boiling points to obtain a copolymer of maleic anhydride and methoxy polyethylene glycol acrylate.

[0055] Step 2: Under nitrogen protection, add 10 g of maleic anhydride and methoxy polyethylene glycol acrylate copolymer and 80 g of toluene to a 250 mL dry three-necked flask, heat to 75°C until it is completely dissolved, and stir for 1 h. Then add 0.1 g of glacial acetic acid, heat to 85°C, and drop 50 g of toluene solution containing 20 g of N-β-aminoethyl-γ-aminopropyl polydimethylsiloxane. The addition is completed within 1 h and the reaction is continued for 5 h. Stop the reaction and cool to room temperature. Heat for 2 h at a vacuum degree of 0.04 MPa and a temperature of 100°C to remove low-boiling substances to obtain a viscous substance, which is a modified aminosiloxane polymer.

[0056] Example 6

[0057] A method for preparing a modified aminopolysiloxane polymer comprises the following steps:

[0058] Step 1: Under nitrogen protection, add 2.5g of maleic anhydride and 237.5g of toluene solvent to a 1000mL dry three-necked flask, heat to 50°C, stir for 1 hour after the maleic anhydride is dissolved, and then add 80g of methoxy polyethylene glycol acrylate; heat to 80°C, drop 10g of toluene solvent containing 0.825g of azobisisoheptanenitrile, and add dropwise for 1.5h. Then stir the reaction at 80°C for 6h and cool to room temperature. Heat at a vacuum degree of 0.05 MPa and a temperature of 110°C for 2h to remove low-boiling substances to obtain a copolymer of maleic anhydride and methoxy polyethylene glycol acrylate.

[0059] Step 2: Under nitrogen protection, add 10g of maleic anhydride and methoxy polyethylene glycol acrylate copolymer and 80g of toluene to a 250mL dry three-necked flask, heat to 75℃ until it is completely dissolved, and stir for 1h. Then add 0.1g of glacial acetic acid, heat to 85℃, and drop 50g of toluene solution containing 30g of N-(β-aminoethyliminoethyl)-γ-aminopropylaminopolydimethylsiloxane. The addition is completed within 1h and the reaction is carried out for 6h. Stop the reaction and cool to room temperature. Heat for 2h under vacuum degree of 0.04MPa and temperature of 100℃ to remove low boiling points to obtain a viscous substance, which is a modified aminosiloxane polymer.

[0060] Example 7

[0061] A method for preparing a modified aminopolysiloxane polymer comprises the following steps:

[0062] Step 1: Under nitrogen protection, add 2.5g of maleic anhydride and 267.5g of toluene solvent to a 1000mL dry three-necked flask, heat to 50°C, stir for 1 hour after the maleic anhydride is dissolved, and then add 70g of methoxy polyethylene glycol acrylate; heat to 80°C, drop 10g of toluene solvent containing 0.925g of azobisisoheptanenitrile, and add dropwise for 1.5h. Then stir the reaction at 80°C for 5h and cool to room temperature. Heat at 110°C for 3h under vacuum degree of 0.05MPa to remove low boiling substances to obtain a copolymer of maleic anhydride and methoxy polyethylene glycol acrylate.

[0063] Step 2: Under nitrogen protection, add 10g of maleic anhydride and methoxy polyethylene glycol acrylate copolymer and 80g of toluene to a 250mL dry three-necked flask, heat to 75℃ until all dissolved, and stir for 1h. Then add 0.1g of glacial acetic acid, heat to 85℃, and drop 50g of toluene solution containing 40g of N-(β-aminoethyliminoethyl)-γ-aminopropylaminopolydimethylsiloxane. The addition is completed within 1h and the reaction is carried out for 5h. Stop the reaction and cool to room temperature, heat for 2h under vacuum degree of 0.04 MPa and temperature of 100℃, remove low boiling points, and obtain a viscous substance, which is a modified aminosiloxane polymer.

[0064] Example 8

[0065] A method for preparing a modified aminopolysiloxane polymer comprises the following steps:

[0066] Step 1: Under nitrogen protection, add 2.5g of maleic anhydride and 187.5g of toluene solvent to a 500 mL dry three-necked flask, heat to 50°C, stir for 1h after the maleic anhydride is dissolved, then add 60g of methoxy polyethylene glycol acrylate; heat to 80°C, drop 10g of toluene solvent containing 0.625g of azobisisoheptanenitrile, and add dropwise for 1.5h. Then stir the reaction at 80°C for 5h and cool to room temperature. Heat at 110°C for 3h under vacuum degree of 0.05 MPa to remove low-boiling substances to obtain a copolymer of maleic anhydride and methoxy polyethylene glycol acrylate.

[0067] Step 2: Under nitrogen protection, add 10g of maleic anhydride and methoxy polyethylene glycol acrylate copolymer and 80g of toluene to a 250 mL dry three-necked flask, heat to 75°C until it is completely dissolved, and stir for 1h. Then add 0.1g of glacial acetic acid, heat to 85°C, and drop 50g of toluene solution containing 40g of N-(β-aminoethyliminoethyl)-γ-aminopropylaminopolydimethylsiloxane. The addition is completed within 1h and the reaction is carried out for 6h. Stop the reaction and cool to room temperature, heat for 2h under vacuum degree of 0.03MPa and temperature of 120°C, remove low boiling points, and obtain a viscous substance, which is a modified aminosiloxane polymer.

[0068] The modified aminosiloxane polymer obtained by the present invention has the following reaction equation and structure:

[0069]

[0070] As can be seen from the above formula, the modified aminopolysiloxane introduces ether groups, ester groups, amide groups and methylsiloxane respectively. The ether groups, ester groups and carboxylic acid groups in the polymer can "bond" with carbon dioxide through the Lewis acid-base model, increasing the solubility of the polymer in supercritical carbon dioxide; at the same time, the aminopolysiloxane hydrophobic groups introduced provide flexibility to the polymer due to the presence of silicon atoms, increase the free volume of the polymer, weaken the polymer-polymer interaction, and achieve the effect of polymerization thickening. At the same time, the modified aminopolysiloxane can form a network structure with the additive, further enhancing the viscosity of supercritical carbon dioxide.

[0071] The viscosity of the thickener prepared by the present invention was tested, and the evaluation results are shown in Table 1.

[0072] Table 1: Thickener viscosity evaluation results

[0073]

[0074] Comparative 1 in Table 1 is commercially available Dow Corning polydimethylsiloxane.

[0075] Comparative 2 is commercially available polydimethylsiloxane.

[0076] As can be seen from Table 1, the viscosity test result of experimental sample 1 is the best. At the same time, the shear resistance of the thickener prepared by the present invention in liquid or supercritical carbon dioxide is characterized, such as Figure 3 The test data show that the modified aminopolydimethylsiloxane prepared by the present invention has strong shear resistance.

[0077] In the present invention, maleic anhydride is used as a "bridge" for modified aminopolysiloxane, and the monomer has both double bonds and carboxylic anhydride functional groups, which can link specific groups with different functions: on the one hand, specific functional groups can be flexibly introduced, such as monomers containing polyethylene glycol groups that are pro-carbon dioxide, to increase the solubility of the target product in supercritical carbon dioxide, and siloxane is introduced at the same time to increase the free volume of the polymer to achieve the purpose of thickening carbon dioxide; on the other hand, maleic anhydride and aminopolysiloxane undergo an amidation reaction, the molecular weight of the aminopolysiloxane is adjustable, the reaction principle is simple, the product performance parameters are controllable, the time is short and the efficiency is high.

Claims

1. A method for preparing a modified aminopolysiloxane polymer, characterized in that: The following steps are involved: Step 1: under an inert gas atmosphere, methoxy polyethylene glycol acrylate is added to a maleic anhydride solution, an initiator is added dropwise for sufficient reaction, and a copolymer of maleic anhydride and methoxy polyethylene glycol acrylate is obtained after purification; the molar ratio of maleic anhydride to methoxy polyethylene glycol acrylate is 1:2-10; Step 2: Under an inert gas atmosphere, a catalyst is added to the copolymer solution obtained in step 1, and aminopolysiloxane is added dropwise for sufficient reaction, and then purified to obtain the desired modified aminopolysiloxane polymer; the mass ratio of the copolymer to the aminopolysiloxane is 1:1 to 3.5; the aminopolysiloxane is a side chain aminopolysiloxane, which is N-(β-aminoethyliminoethyl)-γ-aminopropylpolysiloxane.

2. The method for preparing a modified aminopolysiloxane polymer according to claim 1, characterized in that: In step 1, the initiator is one or a mixture of two or more of benzoyl peroxide, azobisisobutyronitrile and azobisisoheptylnitrile in any proportion; wherein the added amount of the initiator is 0.5 wt.% to 1.5 wt.% of the total mass of maleic anhydride and methoxy polyethylene glycol acrylate.

3. The method for preparing a modified aminopolysiloxane polymer according to claim 1, characterized in that: The reaction temperature in step 1 is 70-85° C., and the reaction time is 3-8 hours.

4. The method for preparing a modified aminopolysiloxane polymer according to claim 1, characterized in that: The catalyst is one or two of hydrochloric acid, phosphoric acid, formic acid, acetic acid and oxalic acid mixed in any proportion, and the added amount of the catalyst accounts for 0.1 wt.% to 1.2 wt.% of the mass of the copolymer.

5. The method for preparing a modified aminopolysiloxane polymer according to claim 1, characterized in that: The reaction temperature in step 2 is 75-90° C., and the reaction time is 3-8 hours.

6. The method for preparing a modified aminopolysiloxane polymer according to claim 1, characterized in that: The reaction solvent in step 1 and step 2 is toluene; after the reaction in step 1 and step 2 is completed, impurities are removed by reduced pressure distillation.

7. Use of the modified aminopolysiloxane polymer obtained by any one of the preparation methods of claims 1 to 6, characterized in that: The modified aminopolysiloxane is used as a supercritical carbon dioxide thickener.

8. The use of a modified aminopolysiloxane polymer according to claim 7, characterized in that: The modified aminopolysiloxane is added with an auxiliary agent to obtain a supercritical carbon dioxide thickener with a mass concentration of 1 wt.% to 2.5 wt.%.

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