Surface active polymer as well as preparation method and application thereof

Abstract

The invention provides a surface active polymer as well as a preparation method and application thereof, and belongs to the technical field of functional high-molecular compounds. The surface active functional monomer, N-isopropylacrylamide, acrylamide, [2-(methylacryloyloxy) ethyl] dimethyl-(3-sulfopropyl) ammonium hydroxide, an initiator and water are subjected to a polymerization reaction in a catalyst system, and the surface active polymer is obtained. The surface active polymer prepared by the invention has excellent temperature resistance and salt tolerance, and can realize rapid and reversible conversion of'high-temperature emulsification and low-temperature demulsification 'under temperature stimulation.

Description

Technical Field

[0001] The present invention relates to the technical field of functional polymer compounds, and particularly relates to a surface-active polymer, a preparation method thereof, and an application thereof. Background Art

[0002] The polymer flooding technology for tertiary oil recovery has become the most realistic and reliable method for increasing recoverable reserves and stabilizing the existing crude oil production in oil fields in China. However, with the gradual reduction of high-quality resources, medium-low permeability high-temperature and high-salt reservoirs will be the main replacement resources for increasing reserves and production in the future. However, in the existing polymer flooding technologies for medium-low permeability high-temperature and high-salt reservoirs, most polymers have problems such as poor salt resistance, poor solubility, and poor viscosity-increasing performance.

[0003] Therefore, there is an urgent need to provide a surface-active polymer with excellent temperature and salt resistance. Summary of the Invention

[0004] In view of one or more technical problems existing in the prior art, the present invention provides a surface-active polymer, a preparation method thereof, and an application thereof. By using the SET-LRP method to synthesize a temperature-responsive quaternary copolymer, it has excellent temperature and salt resistance, and can achieve rapid and reversible "high-temperature emulsification and low-temperature demulsification" under temperature stimulation.

[0005] In a first aspect, the present invention provides a preparation method of a surface-active polymer, which is characterized by comprising:

[0006] Performing a polymerization reaction on a surface-active functional monomer, N-isopropylacrylamide, acrylamide, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide, an initiator, and water under a catalyst system to obtain the surface-active polymer.

[0007] Preferably, the surface-active functional monomer is a first functional monomer or a second functional monomer; wherein, the preparation raw materials of the first functional monomer include cardanol polyoxyethylene ether and allyl glycidyl ether; the preparation raw materials of the second functional monomer include fatty alcohol polyoxypropylene polyoxyethylene ether and allyl glycidyl ether.

[0008] Preferably, the first functional monomer is prepared by the following method: Mix cardanol polyoxyethylene ether and potassium hydroxide, adjust the temperature to 60-120°C, add allyl glycidyl ether, and carry out a ring-opening reaction to obtain a first surface-active functional monomer.

[0009] Preferably, the second functional monomer is prepared by the following method: Mix fatty alcohol polyoxypropylene polyoxyethylene ether and potassium hydroxide, adjust the temperature to 90-110°C, add allyl glycidyl ether, and carry out a ring-opening reaction to obtain a surface-active functional monomer.

[0010] Preferably, after the ring-opening reaction, the reaction solution after the ring-opening reaction is subjected to rotary evaporation.

[0011] Preferably, the catalytic system is prepared by the following method: In a nitrogen atmosphere, CuBr, tris-(2-dimethylaminoethyl)amine, and water are mixed evenly, and then through a disproportionation reaction, the catalytic system is obtained.

[0012] Preferably, the molar ratio of the initiator, CuBr, and tris-(2-dimethylaminoethyl)amine is 2:(2-4):10.

[0013] Preferably, in a nitrogen atmosphere, it includes:

[0014] (1) The initiator and N-isopropylacrylamide are added to water and mixed evenly to obtain a mixed solution;

[0015] (2) The mixed solution is added to the catalytic system for reaction to obtain a prepolymer system;

[0016] (3) The surface-active functional monomer, acrylamide, and [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide are added to water and mixed evenly to obtain a second mixed solution; and the second mixed solution is added to the prepolymer system for polymerization reaction to obtain the surface-active polymer.

[0017] Preferably, the molar ratio of acrylamide, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide, and the surface-active functional monomer is 0.8:(0.04-0.16):(0.04-0.16); the molar amount of N-isopropylacrylamide accounts for 20%-80% of the sum of the molar amounts of the surface-active functional monomer, N-isopropylacrylamide, acrylamide, and [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide.

[0018] Preferably, the molar ratio of acrylamide, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide, and the first functional monomer is 0.8:0.08:0.12; the molar amount of N-isopropylacrylamide accounts for 80% of the sum of the molar amounts of the first functional monomer, N-isopropylacrylamide, acrylamide, and [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide.

[0019] Preferably, the molar ratio of acrylamide, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide, and the second functional monomer is 0.8:0.16:0.04; the molar amount of N-isopropylacrylamide accounts for 66.6% of the sum of the molar amounts of the second functional monomer, N-isopropylacrylamide, acrylamide, and [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide.

[0020] Preferably, the initiator is an organic halo initiator containing a halogen end group.

[0021] Preferably, the initiator is at least one of methyl 2-bromopropionate, ethyl 2-bromopropionate, ethyl 2-bromophenylacetate, 2-bromoisobutyric acid, p-toluenesulfonyl chloride, 2-chloropropionamide, and α-bromoisobutyric acid.

[0022] Preferably, the molar amount of the initiator accounts for 0.4 - 1.6% of the sum of the molar amounts of the surface active functional monomer, N-isopropylacrylamide, acrylamide, and [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide.

[0023] In a second aspect, the present invention provides a surface active polymer prepared by the method described in the first aspect above.

[0024] In a third aspect, the present invention provides an application of a surface active polymer as a flooding agent in an oilfield.

[0025] Preferably, the surface active polymer is applied in offshore oilfields and deep high-temperature reservoirs.

[0026] Compared with the prior art, the present invention has at least the following beneficial effects:

[0027] The present invention uses a self-made surface active functional monomer, N-isopropylacrylamide (NIPAM), acrylamide, and [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide (DMMPPS), and synthesizes a surface active polymer through the SET-LRP method. In this way, the surface active polymer has both hydrophilic groups and hydrophobic groups, and simultaneously undergoes significant phase separation (demulsification phenomenon) at low temperatures and maintains a stable emulsified state through the hydrophobic-hydrophilic dynamic balance at high temperatures, thereby achieving a rapid and reversible "high-temperature emulsification, low-temperature demulsification" conversion under temperature stimulation; moreover, it can reduce the surface tension to 40 mN / m in simulated brine and has excellent temperature and salt resistance.

[0028] The surface-active polymer prepared by the present invention is particularly suitable for steam flooding reservoirs or heavy oil thermal recovery processes: it can assist in emulsifying and reducing viscosity during the high-temperature steam injection stage, improving oil displacement efficiency; during the low-temperature production stage, rapid oil-water separation can be achieved without the need for additional demulsifiers, significantly reducing the cost of using chemical agents, meeting the requirements of the green transformation of oilfield development. Description of the Drawings

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0030] Figure 1 is the infrared spectrum of the surface-active polymer in Example 1 of the present invention;

[0031] Figure 2 is the nuclear magnetic resonance hydrogen spectrum of the surface-active polymer in Example 1 of the present invention;

[0032] Figure 3 is the infrared spectrum of the surface-active polymer in Example 2 of the present invention;

[0033] Figure 4 is the nuclear magnetic resonance hydrogen spectrum of the surface-active polymer in Example 2 of the present invention;

[0034] Figure 5 is the curve graph of the transmittance of the P(NIPAM-AM-DMMPPS-CP12FM) surface-active polymer solution provided in the embodiment of the present invention varying with temperature at a wavelength of 500 nm;

[0035] Figure 6 is the curve graph of the transmittance of the P(NIPAM-AM-DMMPPS-AEOFM) surface-active polymer solution provided in the embodiment of the present invention varying with temperature at a wavelength of 500 nm;

[0036] Figure 7 is the surface tension-lgc curve graph of the P(NIPAM-AM-DMMPPS-CP12FM) surface-active polymer solution provided in the embodiment of the present invention;

[0037] Figure 8 is the surface tension-lgc curve graph of the P(NIPAM-AM-DMMPPS-AEOFM) surface-active polymer solution provided in the embodiment of the present invention;

[0038] Figure 9It is the curve graph of the change in the oil-water interfacial tension of the P(NIPAM-AM-DMMPPS-CP12FM) surfactant polymer solution provided by the embodiments of the present invention;

[0039] Figure 10 It is the curve graph of the change in the oil-water interfacial tension of the P(NIPAM-AM-DMMPPS-AEOFM) surfactant polymer solution provided by the embodiments of the present invention;

[0040] Figure 11 It is the result graph of the oil-water system composed of the P(NIPAM-AM-DMMPPS-CP12FM) surfactant polymer solution and paraffin in the polymer oil-water system provided by Embodiment 1 of the present invention;

[0041] Figure 12 It is the result graph of the oil-water system composed of the P(NIPAM-AM-DMMPPS-AEOFM) surfactant polymer solution and paraffin in the polymer oil-water system provided by Embodiment 2 of the present invention. Detailed implementation manners

[0042] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0043] The present invention provides a preparation method of a surfactant polymer in the first aspect, which is characterized by including:

[0044] Performing a polymerization reaction on a surfactant functional monomer, N-isopropylacrylamide, acrylamide, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide, an initiator and water under a catalyst system to obtain a surfactant polymer.

[0045] In a preferred embodiment, the surfactant functional monomer is a first functional monomer or a second functional monomer; wherein, the raw materials for preparing the first functional monomer include cardanol polyoxyethylene ether and allyl glycidyl ether; the raw materials for preparing the second functional monomer include fatty alcohol polyoxypropylene polyoxyethylene ether and allyl glycidyl ether.

[0046] For the first functional monomer, its preparation method includes: mixing cardanol polyoxyethylene ether and potassium hydroxide, adjusting the temperature to 60 - 120 °C (for example, 60 °C, 70 °C, 80 °C, 90 °C, 100 °C, 110 °C or 120 °C), adding allyl glycidyl ether, and through ring-opening reaction, obtaining the first surface-active functional monomer. Among them, the dosage of potassium hydroxide is 0.5 wt% - 2 wt% of cardanol polyoxyethylene ether (for example, 0.5 wt%, 1 wt%, 1.5 wt% or 2 wt%); the molar ratio of cardanol polyoxyethylene ether to allyl glycidyl ether is (1.1 - 1.3):1 (for example, 1.15:1, 1.2:1 or 1.25:1); the reaction time is 1 - 24 h (for example, 1 h, 2 h, 4 h, 6 h, 8 h, 10 h, 15 h, 20 h or 24 h).

[0047] The reaction formula of the first functional monomer (CP12FM) is:

[0048]

[0049] Specifically, add cardanol polyoxyethylene ether and potassium hydroxide (the dosage of potassium hydroxide is 1 wt% of cardanol polyoxyethylene ether) into a four-necked flask equipped with a stirrer, a condenser and a thermometer. Under the condition of 90 °C, slowly dropwise add allyl glycidyl ether (the molar ratio of cardanol polyoxyethylene ether to allyl glycidyl ether is 1.2:1), and then carry out ring-opening reaction for 2 h to obtain the first functional monomer.

[0050] For the second functional monomer, its preparation method includes: mixing fatty alcohol polyoxypropylene polyoxyethylene ether and potassium hydroxide, adjusting the temperature to 90 - 110 °C (for example, 90 °C, 95 °C, 100 °C, 105 °C or 110 °C), adding allyl glycidyl ether, and through ring-opening reaction, obtaining the surface-active functional monomer. Among them, the volume ratio of fatty alcohol polyoxypropylene polyoxyethylene ether to allyl glycidyl ether is preferably (100 - 106):(13 - 14); the dosage ratio of potassium hydroxide to fatty alcohol polyoxypropylene polyoxyethylene ether is preferably (1 - 1.2) g:(100 - 106) mL.

[0051] The reaction formula of the second functional monomer (AEOFM) is:

[0052]

[0053] According to some preferred embodiments, after the ring-opening reaction, it further includes the steps of dialyzing the reaction filtrate in distilled water and freeze-drying. In the present invention, the reaction filtrate after polymerization is placed in distilled water (MWCO = 5000 g / mol) for two days to remove residual monomers and small molecules, and then high-purity surface-active functional monomers are obtained through freeze-drying.

[0054] According to some preferred embodiments, after the ring-opening reaction, the reaction solution after the ring-opening reaction is subjected to rotary evaporation.

[0055] In the preparation process of the surface-active functional monomer of the present invention, potassium hydroxide plays a catalytic role.

[0056] Specifically, fatty alcohol polyoxypropylene polyoxyethylene ether and potassium hydroxide are added to a four-necked flask, and zeolite is added to prevent bumping. After reflux condensation and heating to 100 °C, allyl glycidyl ether is slowly added dropwise. After the addition is complete, the reaction continues for 2 h. Then, through rotary evaporation, the second functional monomer is obtained and purified.

[0057] The raw materials for preparing the first functional monomer of the present invention include cardanol polyoxyethylene ether and allyl glycidyl ether; this monomer has a block structure, and its molecular structure simultaneously has a hydrophilic EO chain segment, a hydrophobic long alkyl chain, and polymerizable carbon-carbon double bonds. The raw materials for preparing the second functional monomer of the present invention include fatty alcohol polyoxypropylene polyoxyethylene ether and allyl glycidyl ether; this monomer has a block structure, and its molecular structure simultaneously has a hydrophilic EO chain segment, a hydrophobic long alkyl chain, a PPO chain segment, and polymerizable carbon-carbon double bonds. When the above surface-active functional monomer is added to an aqueous solution, the hydrophilic chain segments therein extend in the aqueous phase, and the hydrophobic chain segments leave the gas-liquid interface, which can make the surface-active polymer molecules containing the surface-active functional monomer align neatly at the gas-liquid interface, presenting the morphology of a molecular brush, which is beneficial to rapidly reducing the surface tension of the aqueous solution. In addition, the long-chain hydrophobic groups / segments in the surface-active functional monomer can undergo hydrophobic association effects in salt water, having a better thickening effect.

[0058] It should be noted that in the present invention, cardanol polyoxyethylene ether is purchased from Macklin Reagent Company in Shanghai, China, fatty alcohol polyoxypropylene polyoxyethylene ether is purchased from Shandong Yousuo Chemical Technology Co., Ltd. (C24E9, purity 99%), and allyl glycidyl ether is purchased from Shanghai Bangcheng Chemical Co., Ltd. (AR, 99%).

[0059] In a preferred embodiment, the preparation method of the catalyst system includes: in a nitrogen atmosphere, CuBr, tris-(2-dimethylaminoethyl)amine, and deionized water are mixed, and through a disproportionation reaction, the catalyst system is obtained.

[0060] In a more preferred embodiment, the molar ratio of the initiator, CuBr, and tris-(2-dimethylaminoethyl)amine is 2:(2-4):10 (for example, it can be 2:2:10, 2:2.5:10, 2:3:10, 2:3.5:10, or 2:4:10).

[0061] The present invention uses zero-valent copper (Cu 0 ) and a complex of divalent copper and a ligand (Cu II Br2 / Me6TREN) obtained by in-situ disproportionation of cuprous bromide (CuBr) and tris-(2-dimethylaminoethyl)amine (Me6TREN) as a catalytic system. Using this catalytic system, aqueous living radical polymerization of a surface-active functional monomer, N-isopropylacrylamide, acrylamide, and [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide can be achieved at room temperature to obtain a surface-active polymer.

[0062] Specifically, CuBr and deionized water are added to a vacuum reaction tube, and tris-(2-dimethylaminoethyl)amine (Me6TREN) is added. After deoxygenation by nitrogen bubbling for 10 min, a Cu(II) disproportionation reaction is carried out in an ice-water bath for 20 min to promote the formation of active Cu(0), obtaining a catalytic system.

[0063] In a preferred embodiment, the initiator is an organic halide initiator containing a halogen end group; preferably, the initiator is at least one of methyl 2-bromopropionate, ethyl 2-bromopropionate, ethyl 2-bromophenylacetate, 2-bromoisobutyric acid, p-toluenesulfonyl chloride, 2-chloropropionamide, and α-bromoisobutyric acid.

[0064] In a preferred embodiment, the molar amount of the initiator accounts for 0.4 - 1.6% of the sum of the molar amounts of the surface-active functional monomer, N-isopropylacrylamide, acrylamide, and [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide.

[0065] In a preferred embodiment, the preparation method of the surface-active polymer is carried out under a nitrogen atmosphere and includes:

[0066] (1) Mixing the initiator and N-isopropylacrylamide in water to obtain a mixed solution;

[0067] (2) Adding the mixed solution to the catalytic system for reaction to obtain a prepolymer system;

[0068] (3) Mixing the surface-active functional monomer, acrylamide, and [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide in water to obtain a second mixed solution; and adding the second mixed solution to the prepolymer system for polymerization reaction to obtain a surface-active polymer.

[0069] It should be noted that the water in the above steps is preferably deionized water, and the amount of water used only needs to enable all raw materials to be fully dissolved.

[0070] In a preferred embodiment, the molar ratio of acrylamide, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide, and the surface-active functional monomer is 0.8:(0.04 - 0.16):(0.04 - 0.16) (for example, it can be 0.8:0.04:0.04, 0.8:0.06:0.04, 0.8:0.08:0.04, 0.8:0.10:0.04, 0.8:0.12:0.04, 0.8:0.14:0.04, or 0.8:0.16:0.04); the molar amount of N-isopropylacrylamide accounts for 20% - 80% of the sum of the molar amounts of the surface-active functional monomer, N-isopropylacrylamide, acrylamide, and [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide (for example, it can be 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, or 80%).

[0071] In a more preferred embodiment, the molar ratio of acrylamide, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide, and the first functional monomer is 0.8:0.08:0.12; the molar amount of N-isopropylacrylamide accounts for 80% of the sum of the molar amounts of the first functional monomer, N-isopropylacrylamide, acrylamide, and [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide.

[0072] In a more preferred embodiment, the molar ratio of acrylamide, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide, and the second functional monomer is 0.8:0.16:0.04; the molar amount of N-isopropylacrylamide accounts for 66.6% of the sum of the molar amounts of the second functional monomer, N-isopropylacrylamide, acrylamide, and [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide.

[0073] Under the conditions of an initiator and a catalytic system, the present invention successfully achieved aqueous-phase living radical polymerization of acrylamide (AM), N-isopropylacrylamide (NIPAM), [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide (DMMPPS), and the surface-active functional monomer (CP12FM or AEOFM) in a solvent water system at room temperature through single-electron transfer living radical polymerization, obtaining the surface-active polymer P(NIPAM-AM-DMMPPS-CP12FM) or the surface-active polymer P(NIPAM-AM-DMMPPS-AEOFM).

[0074] The present invention also provides a surface-active polymer, which is prepared by using any one of the above-mentioned preparation methods.

[0075] The present invention also provides an application of the surface-active polymer, which is used as an oil displacement agent in oil fields, preferably in offshore oil fields and deep high-temperature reservoirs.

[0076] In order to more clearly illustrate the technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with embodiments.

[0077] It should be noted that the test methods for the performance data of the surface-active polymer prepared in the embodiments of the present invention are as follows:

[0078] (a) Infrared spectrum: It is measured by a Bruker-Vector 22 type FT-IR spectrometer (Bruker Company, Germany), and KBr is used for pressing tablets.

[0079] (b) Proton nuclear magnetic resonance spectrum: Using deuterated chloroform as the solvent, it is measured by a Bruker-500 MHz nuclear magnetic resonance spectrometer (Bruker Company, Germany), and tetramethylsilane (TMS) is used as the internal standard.

[0080] (c) Measurement of light transmittance: An aqueous solution of the surface-active polymer with a mass fraction of 0.01 wt% is prepared respectively, and the light transmittance is tested by a QBZY ultraviolet spectrophotometer of Shanghai Yidian Analytical Instrument Co., Ltd. Before the test, the instrument is normalized and corrected with the light transmittance of pure water at 100%, and the test wavelength is selected as visible light at 500 nm.

[0081] (d) Measurement of surface tension: The surface tension of the surface-active polymer solution is measured by a 722N surface tension meter of Shanghai Fangrui Instrument Co., Ltd. Aqueous solutions of the surface-active polymer with concentrations of 10 -5 、10 -4.5 、10 -4 、10 -3.5 、10 -3 、10 -2.5 、10 -2 、10 -1.5 、10 -1 、10 -0.5 、1 g / L are prepared respectively, and the surface tension value of the sample liquid is measured by the platinum plate method. A relationship curve is plotted with the surface tension (γ) as the ordinate and the logarithm of the concentration (lgc) as the abscissa. The concentration corresponding to the inflection point of the curve is the critical micelle concentration (CMC) of the surface-active polymer at this temperature.

[0082] (e) Measurement of interfacial tension: The interfacial tension was measured according to the internal rotating drop method of the petroleum and natural gas industry standard SY / T 5370-2018. Surfactant polymer solutions with different concentrations were prepared with 20000 mg / L mineralized water. The measuring tube was cleaned with acetone, then rinsed with distilled water, and finally rinsed twice with the surfactant polymer solution to be measured and set aside. Kerosene was used as the simulated oil, and an American Keno Industrial model 500C interfacial tension meter was used to measure the change in the diameter of the oil droplets to calculate the interfacial tension. Among them, 20000 mg / L mineralized water was obtained by dissolving 1.73 g of calcium chloride, 1.17 g of magnesium chloride, 5.27 g of sodium sulfate, and 11.83 g of sodium chloride in distilled water and diluting to a total volume of 1 L.

[0083] (f) Measurement of demulsification / emulsification performance: Surfactant polymer solutions with mass concentrations of 0.1 wt%, 0.01 wt%, and 0.001 wt% were respectively prepared. Paraffin oil was used as the simulated oil, Sudan IV was used as the oil-phase dye, and an oil-water system was formed by taking paraffin oil and surfactant polymer solutions with different concentrations at an oil-water volume ratio of 1:1. Then, the emulsification-demulsification behavior was investigated at different temperatures.

[0084] In the following examples: The first functional monomer was prepared by the following method: 83.2 g of cardanol polyoxyethylene ether and potassium hydroxide (the amount of potassium hydroxide was 1 wt% of cardanol polyoxyethylene ether) were added to a 250 mL four-necked flask equipped with a stirrer, a condenser, and a thermometer. At 90 °C, allyl glycidyl ether (the molar ratio of cardanol polyoxyethylene ether to allyl glycidyl ether was 1.2:1) was slowly added dropwise, and after the ring-opening reaction for 2 h, the first functional monomer (CP12FM) was obtained.

[0085] The second functional monomer was prepared by the following method: After washing and drying the four-necked flask, 105.58 mL of fatty alcohol polyoxypropylene polyoxyethylene ether was accurately measured and 1.09 g of catalyst KOH was added; zeolite was added to prevent bumping, reflux condensation was carried out, and after heating to 100 °C, 13.5 mL of allyl glycidyl ether was slowly added dropwise. After the addition was completed, the reaction continued for 2 h. After rotary evaporation, the second functional monomer (AEOFM) was obtained and then purified.

[0086] Example 1

[0087] (1) In vacuum reaction tube I, initiator 2-bromo-2-methylpropionic acid (0.02 mmol) and N-isopropylacrylamide (1 mmol) were added to 1.5 mL of deionized water and ultrasonically dispersed until completely dissolved. The oxygen in the system was removed, and a protective gas nitrogen was filled to maintain an inert atmosphere to obtain a mixed solution;

[0088] (2) Add the catalyst CuBr (0.04 mmol) and 1 mL of deionized water into the vacuum reaction tube II, add tris-(2-dimethylaminoethyl)amine (0.1 mmol), after 10 min of nitrogen bubbling for deoxidation, conduct the Cu(II) disproportionation reaction in an ice-water bath for 20 min to obtain the catalyst system; after standing for a period of time until the temperature in the vacuum reaction tube is consistent with the room temperature, quickly transfer the mixture in step (1) to the catalyst system (vacuum reaction tube II) by Schlenk technique, seal it, and conduct the chain initiation and growth reaction at 25 °C for 30 min to obtain the prepolymer system;

[0089] (3) In the vacuum reaction tube III, configure the mixed monomer system of the first functional monomer (CP12FM), acrylamide, and [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide according to the molar ratio of N-isopropylacrylamide, acrylamide, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide, and the first functional monomer of 1:0.8:0.08:0.12, then add 1.5 mL of deionized water and ultrasonically dissolve it for 30 min. After deoxidation treatment, quantitatively transfer this mixed monomer system to the vacuum reaction tube II under nitrogen protection by double syringe technique, and continue the polymerization reaction for 2 h. After the reaction is completed, obtain the surface-active polymer. After the reaction is completed, load the reaction solution into a dialysis bag with a molecular weight cut-off of 3500, dialyze it with pure water for 48 h, and change the water every 8 h to remove the impurities during the reaction. The liquid obtained after dialysis is freeze-dried in a vacuum freeze dryer until all the water is removed to obtain a white solid product P(NIPAM-AM-DMMPPS-CP12FM). At this time, the yield of the surface-active polymer is 78.41%.

[0090] The reaction formula of the surface-active polymer P(NIPAM-AM-DMMPPS-CP12FM) is:

[0091]

[0092] From Figure 1 it can be seen that in the infrared spectrum of the surface-active polymer prepared in Example 1, 3294 cm -1 is the stretching vibration absorption peak of secondary amine N-H in the amide group of the PNIPAM chain segment, 2927 cm -1 is the stretching vibration absorption peak of saturated C-H, 1458 cm -1 is the bending vibration peak of the main chain -CH2-, 1652 cm -1 is the stretching vibration peak of -O-C=O, 1256 cm -1 is the stretching vibration of tertiary amine C-N, 1111 cm -1 is the absorption peak of -CH2-O-CH2- in the main chain, 698 cm-1 is the vibration peak of aromatic ring = C-H, which confirms the successful synthesis of P(NIPAM-AM-DMMPPS-CP12FM).

[0093] From Figure 2 it can be seen that in the 1H NMR spectrum of the surfactant polymer prepared in Example 1, the chemical shift δ: 0.8 - 2.3 ppm represents the proton peaks of -CH3 and -CH2- groups; the chemical shift at 2.8 - 3.2 ppm corresponds to the proton peak of the methylene group connected to the amide group. The peak at the chemical shift of 3.2 - 3.8 ppm is the proton peak of the hydrogen on groups such as a, g, c, d, f, e, etc. The chemical shift of 3.5 - 3.6 ppm represents the proton peak of the -O-CH2-CH2-O- group in the first functional monomer (CP12FM). The chemical shift of 6.5 - 6.7 ppm is the proton peak of the benzene ring skeleton. The chemical shift of 6.5 - 7.0 ppm corresponds to the proton peak of the -NH2 group and the para position b of the alkyl group on the benzene ring. The analysis of the NMR spectrum results further confirms the synthesis of the target product P(NIPAM-AM-DMMPPS-CP12FM). Gel permeation chromatography was used to test the molecular weight and molecular weight distribution of the target product, and the molecular weight distribution index was obtained as PDI = 1.46. The molecular weight distribution of the sample is relatively narrow, indicating that the polymerization system has controllability.

[0094] Example 2

[0095] (1) Add initiator α-bromoisobutyric acid (0.02 mmol) and N-isopropylacrylamide (1 mmol) to 1.5 mL of deionized water in vacuum reaction tube Ⅰ, and ultrasonically disperse until completely dissolved. Evacuate the oxygen in the system and fill with nitrogen to maintain an inert atmosphere to obtain a mixed solution;

[0096] (2) Add catalyst CuBr (0.02 mmol) and 1 mL of deionized water to vacuum reaction tube Ⅱ, add tris-(2-dimethylaminoethyl)amine (0.1 mmol), after deoxygenation by nitrogen bubbling for 10 min, carry out the Cu(II) disproportionation reaction in an ice-water bath for 15 min to obtain a catalyst system; After standing for a period of time until the temperature in this vacuum reaction tube is consistent with room temperature, quickly transfer the mixed solution in step (1) to the catalyst system (vacuum reaction tube Ⅱ) by Schlenk technique, seal it, and carry out the chain initiation and growth reaction at 25 °C for 30 min to obtain a prepolymer system;

[0097] (3) In the vacuum reaction tube Ⅲ, a mixed monomer system of the second functional monomer (AEOFM), acrylamide, and [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide is prepared according to the molar ratio of N-isopropylacrylamide, acrylamide, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide, and the second functional monomer of 1:0.8:0.16:0.04. Then, 1.5 mL of deionized water is added, and the mixture is ultrasonically dissolved for 30 min. After deoxygenation treatment, the mixed monomer system is quantitatively transferred to the vacuum reaction tube Ⅱ under nitrogen protection by the double-row needle technique, and the polymerization reaction continues for 2 h. After the reaction ends, a surface-active polymer is obtained. After the reaction ends, the reaction solution is filled into a dialysis bag with a cut-off molecular weight of 3500 and dialyzed with pure water for 48 h, changing the water every 8 h to remove impurities during the reaction. The liquid obtained after dialysis is freeze-dried in a vacuum freeze dryer until all the water is removed, and a white solid product P(NIPAM-AM-DMMPPS-AEOFM) is obtained. At this time, the yield of the surface-active polymer is 55.82%.

[0098] The reaction formula of the surface-active polymer P(NIPAM-AM-DMMPPS-AEOFM) is:

[0099]

[0100] From Figure 3 it can be seen that in the infrared spectrum of the surface-active polymer prepared in Example 2, the stretching vibration peak of -NH2 in AM is at 3303 cm -1 , the stretching vibration peaks of S-H in DMMPPS and N-H in NIPAM are at 3200 cm -1 , the stretching vibration peak of -C=O in AM is at 1655 cm -1 , and the stretching vibration peak of C-O-C in AEOFM is at 1175 cm -1 . The stretching vibration peaks of NIPAM, AM, DMMPPS, and AEOFM all appear in P(NIPAM-AM-DMMPPS-AEOFM). Thus, it is preliminarily determined that the target product P(NIPAM-AM-DMMPPS-AEOFM) is synthesized.

[0101] From Figure 4It can be seen that in the proton nuclear magnetic resonance spectrum of the surface active polymer prepared in Example 2, the hydrogen proton peak of -NH2 is at the chemical shift δ = 7.56 ppm; the hydrogen proton absorption peak of the methylene group -(CONH2)CH- directly connected to the amide group in the acrylamide monomer unit of the copolymer is at the chemical shift δ = 2.24 ppm, and the hydrogen proton absorption peak of the -CH2 group connected to S in DMMPPS is at the chemical shift δ = 2.24 ppm, further confirming the synthesis of the target product P(NIPAM-AM-DMMPPS-AEOFM). The molecular weight and molecular weight distribution of the target product were tested by gel permeation chromatography, and the weight average molecular weight was 2w, PDI = 1.41, indicating that the molecular weight distribution of the sample was narrow and the system had high controllability.

[0102] Example 3

[0103] Example 3 is basically the same as Example 1, except that: the molar ratio of N-isopropylacrylamide, acrylamide, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide and the first functional monomer is 1:0.8:0.04:0.16. At this time, the yield of the surface active polymer is 73.33%.

[0104] Example 4

[0105] Example 4 is basically the same as Example 1, except that: the molar ratio of N-isopropylacrylamide, acrylamide, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide and the first functional monomer is 1:0.8:0.16:0.04. At this time, the yield of the surface active polymer is 71.40%.

[0106] Example 5

[0107] Example 5 is basically the same as Example 1, except that: in step 1, the amount of N-isopropylacrylamide used is 0.25 mmol, and the sum of the molar amounts of acrylamide, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide and the first functional monomer is 1 mmol. At this time, the yield of the surface active polymer is 67.91%.

[0108] Example 6

[0109] Example 6 is basically the same as Example 1, except that: in step 1, the amount of N-isopropylacrylamide used is 0.66 mmol, and the sum of the molar amounts of acrylamide, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide and the first functional monomer is 1 mmol. At this time, the yield of the surface active polymer is 73.73%.

[0110] Example 7

[0111] Example 7 is basically the same as Example 1, except that: in Step 1, the dosage of N-isopropylacrylamide is 1.5 mmol, and the sum of the molar dosages of acrylamide, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide and the first functional monomer is 1 mmol. At this time, the yield of the surface-active polymer is 81.85%.

[0112] Example 8

[0113] Example 8 is basically the same as Example 1, except that: in Step 1, the dosage of N-isopropylacrylamide is 4 mmol, and the sum of the molar dosages of acrylamide, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide and the first functional monomer is 1 mmol. At this time, the yield of the surface-active polymer is 84.05%.

[0114] Example 9

[0115] Example 9 is basically the same as Example 2, except that: in Step 1, the dosage of N-isopropylacrylamide is 0.5 mmol, and the sum of the molar dosages of acrylamide, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide and the first functional monomer is 1 mmol. At this time, the yield of the surface-active polymer is 52.35%.

[0116] Example 10

[0117] Example 10 is basically the same as Example 2, except that: in Step 1, the dosage of N-isopropylacrylamide is 1.5 mmol, and the sum of the molar dosages of acrylamide, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide and the first functional monomer is 1 mmol. At this time, the yield of the surface-active polymer is 62.13%.

[0118] Example 11

[0119] Example 11 is basically the same as Example 2, except that: in Step 1, the dosage of N-isopropylacrylamide is 2 mmol, and the sum of the molar dosages of acrylamide, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide and the first functional monomer is 1 mmol. At this time, the yield of the surface-active polymer is 81.83%.

[0120] Comparative Example 1

[0121] Comparative Example 1 is basically the same as Example 2, except that: N-isopropylacrylamide is not added in Step 1.

[0122] Figure 5 The transmittance-temperature curves of the aqueous solution of P(NIPAM-AM-DMMPPS-CP12FM), a surfactant polymer in Examples 1, 5 to 8, at a wavelength of 500 nm are shown. Among them, the LCST of Example 5 is 64 °C, the LCST of Example 6 is 46 °C, the LCST of Example 1 is 41 °C, the LCST of Example 7 is 35 °C, and the LCST of Example 8 is 33 °C. It can be seen from this that as the NIPAM chain length increases, the lower critical solution temperature (LCST) gradually decreases. This is because of the amphiphilic characteristics of the NIPAM chain segment: its amide group maintains a hydrated state through a hydrogen bond network, while the isopropyl group imparts hydrophobic properties to the molecule. As the proportion of the NIPAM component increases, the density of hydrophobic microdomains in the copolymer significantly increases. When the temperature reaches the critical point, the dissociation of the hydrogen bond network triggers a conformational transition dominated by hydrophobic association - the cooperative effect of hydrophobic segments enhances the intermolecular association energy, resulting in a decrease in the phase transition temperature with the increase in the concentration of the hydrophobic component. This structure-property relationship verifies the feasibility of precisely regulating the thermal response characteristics of intelligent materials through molecular structure design.

[0123] Figure 6 The transmittance-temperature curves of the aqueous solution of P(NIPAM-AM-DMMPPS-AEOFM), a surfactant polymer in Examples 2, 9 to 11, at a wavelength of 500 nm are shown as Figure 6 shown. Among them, the LCST of Example 2 is 45 °C, the LCST of Example 9 is 52.5 °C, the LCST of Example 10 is 40 °C, and the LCST of Example 11 is 45 °C. It can be seen from this that in Example 9 containing a small amount of thermosensitive unit NIPAM, due to the insufficient concentration of thermal response motifs, although its phase transition temperature reaches 52.5 °C, there is a response hysteresis phenomenon; in contrast, Example 10 exhibits the optimal thermal response characteristics, with its LCST dropping to 40 °C and accompanied by an obvious change in the transmittance of the solution; particularly, although the phase transition threshold of Example 11 is similar to that of Example 2, the attenuation amplitude of the absorbance in the high-temperature region is smaller, indicating that this component still maintains high dissolution stability under thermal stimulation. This gradient change rule stems from the structural characteristics of the PNIPAM chain segment, which simultaneously has amide group hydrogen bond interactions and isopropyl hydrophobic association interactions within the molecule. As the proportion of the thermosensitive chain segment increases, the cooperative effect of hydrophobic groups enhances, resulting in a decrease in the intermolecular association energy barrier during the phase transition, thus manifested as a decrease in LCST.

[0124] Figure 7 The surface tension-lgc curves of the aqueous solution of P(NIPAM-AM-DMMPPS-CP12FM), a surfactant polymer in Examples 1, 5 to 8, at 25 °C are shown. Through analysis, it is found that at a concentration lower than 10 -3When the concentration is [X] g / L, Example 1 exhibits more excellent interfacial activity, and its surface tension value is significantly lower than that of similar materials. This may be because the polar-nonpolar groups of NIPAM and CP12FM act synergistically, prompting the molecules to preferentially orient at the air-liquid interface under low-concentration conditions. At the same mass concentration gradient, as the proportion of the thermosensitive block increases, the surface tension of the quaternary copolymer shows an increasing trend. This is because the increase in the content of NIPAM dilutes the relative concentration of the surface-active motif CP12FM, thus weakening the interfacial adsorption efficiency. The interfacial behavior of this surface-active polymer solution exhibits typical two-stage characteristics: at a concentration range of 10 -4 ~10 -2 g / L, the surface tension decreases rapidly with the increase in concentration. When it reaches 10 -2 g / L, it stabilizes at 40 mN / m. This is due to the amphiphilic molecular self-assembly characteristics of the material: in the initial stage, the hydrophilic AM / DMMPPS segments in the copolymer form a strong solvation layer with water molecules, while the hydrophobic CP12FM groups significantly reduce the free energy of the system through interfacial orientation. As the concentration increases to the critical value of 10 - 2 g / L, the interfacial adsorption reaches the saturation state of monolayer coverage. At this time, the excess molecules in the solution begin to form micelle structures, resulting in a gradual flattening of the change in surface tension.

[0125] Since the P(NIPAM-AM-DMMPPS-CP12FM) surface-active polymer has both hydrophilic and hydrophobic groups, it has special surface activity in aqueous solution. When this surface-active polymer is added to the aqueous solution, the hydrophilic block tends to interact with the aqueous phase, while the hydrophobic block tends to leave the water-air interface, thus effectively reducing the surface tension. At low concentrations, the interaction force between the surface-active polymer molecules is weak, so they can freely arrange at the water-air interface. As the concentration increases, a relatively fast downward trend of the surface tension is shown. As the concentration continues to increase, the interaction between molecules enhances, resulting in an increase in the collision between various groups and a decrease in the activity space, making the downward trend of the surface tension become slow. When the concentration further increases, the surface-active polymer molecules adsorbed on the air-liquid interface have reached saturation, and the surface tension drops to about 40 mN / m, and the surface tension basically no longer changes.

[0126] Figure 8 shows the surface tension-lgc curves of the P(NIPAM-AM-DMMPPS-AEOFM) aqueous solutions of the surface-active polymers in Example 2, Examples 9 to 11, and Comparative Example 1 at 25 °C. Through analysis, it is found that as the solution concentration of the surface-active polymer increases, the surface tension decreases. The ternary copolymer without the thermosensitive component (NIPAM) in Comparative Example 1 has a concentration of 10 -2.5When the concentration is 10 g / L, the surface tension can still be reduced to 43 mN / m, which is attributed to the synergistic effect of the extended surfactant unit (AEOFM) and the amphiphilic segment in its molecular structure: the hydrophobic PDMMPPS segment and the hydrophilic PAM group form a dynamic equilibrium, effectively reducing the gas-liquid interfacial energy. In contrast, Example 2 containing a thermosensitive component exhibits more excellent interfacial activity, and a significant decrease in surface tension can be achieved when the concentration is lower than 10 -3 g / L, which benefits from the precise spatial matching of the polar group (amide group) and the non-polar group (isopropyl / AEOFM alkyl) in its molecule, prompting the molecules to be oriented and arranged at the interface. When the concentration of the surface-active polymer increases to 10 -2 g / L, the surface tension can be reduced to 45 mN / m. Continuing to increase the concentration of the surface-active polymer, the interfacial tension does not change significantly. This is because below the critical concentration, the amphiphilic molecules are preferentially adsorbed on the gas-liquid interface through hydrophobic association; when the monolayer saturation adsorption is reached, the excess molecules form micelle structures in the bulk phase, resulting in the interfacial coverage entering a dynamic equilibrium state. When the polymer P(NIPAM-AM-DMMPPS-AEOFM) is added to the aqueous solution, the synergistic effect of its long-chain alkyl group (AEOFM) and the thermosensitive group (NIPAM) enhances the compactness of the interfacial adsorption layer, but at the same time intensifies the steric hindrance effect between molecules, ultimately leading to a narrowing of the concentration response range of the surface tension change.

[0127] As Figure 9 can be seen, the oil-water interfacial energy regulation performance of the quaternary copolymer P(NIPAM-AM-DMMPPS-CP12FM) shows a significant correlation with its composition parameters. Experiments show that with the increase in the molar fraction of the thermosensitive component (NIPAM), the interfacial tension of this system first rises rapidly and then falls: when the proportion of NIPAM increases to 80%, the interfacial energy reaches the lowest value of 1.06 mN / m. When the proportion of NIPAM exceeds the critical value, the excessive aggregation of hydrophobic groups leads to an enhanced intermolecular association. At this time, the interfacial region has achieved monolayer saturation coverage, and the system enters the adsorption-desorption dynamic equilibrium state, showing a plateau phenomenon in the change of interfacial energy.

[0128] As Figure 10 can be seen, Comparative Example 1 still shows a certain ability to reduce the interfacial tension without adding NIPAM, while Example 10 shows ultra-low interfacial activity characteristics, and its oil-water interfacial tension can be reduced to 0.0024 mN / m, reducing the interfacial tension to 10 -3The order of magnitude significantly improves the oil displacement performance. The interfacial tension of Example 11 is 0.0076 mN / m. The component sensitivity stems from the structure-activity relationship of the thermosensitive chain segment: when the temperature rises to 45 °C, the hydrogen bond network of the amide group in the PNIPAM chain segment dissociates, leading to the formation of isopropyl hydrophobic microdomains. At the same time, the solvation degree of the hydrophilic chain segment of AM / DMMPPS increases. Meanwhile, this dynamic amphiphilic balance enables Example 10 to form a molecular brush-like ordered structure at the oil-water interface: the hydrophobic end anchors to the oil phase, and the hydrophilic end constructs a hydration layer, achieving an ultra-low interfacial energy state by reducing the interfacial Marangoni effect. In contrast, the hydrophobic association effect caused by excessive NIPAM in Example 11 results in rigid molecular conformations, weakening the interfacial self-adaptive arrangement ability.

[0129] Through the measurement of demulsification / emulsification performance, it is found that the surfactant polymers in the above examples all exhibit significant temperature-responsive emulsion regulation behaviors, such as Figure 11 and Figure 12 shown, at 25 °C, phase separation (demulsification phenomenon) occurred, and when the temperature rose to 65 °C, a stable emulsion (emulsified state) was formed. For the surfactant polymer P(NIPAM-AM-DMMPPS-CP12FM), when the temperature decreased to 25 °C, demulsification occurred in each emulsion. At 65 °C, the PNIPAM chain segment forms a core layer structure through hydrophobic association, and the PDMMPPS chain segment is in a solvated extended state, self-assembling into micron-sized micelle particles. At this time, when the surfactant solution is mixed with the oil phase, the colloidal particles can adsorb on the oil-water interface to form a stable emulsion. When the temperature drops to 25 °C, both the PNIPAM chain segment and the PDMMPPS chain segment are in a hydrophilic extended state, resulting in demulsification. At 65 °C, surfactant polymer solutions with concentrations of 0.1 wt% and 0.01 wt% can both form stable emulsions, while the solution with a concentration of 0.001 wt% did not form a stable emulsion due to the too low polymer concentration.

[0130] For the surface-active polymer P(NIPAM-AM-DMMPPS-AEOFM), at high temperatures, the temperature-responsive polymer PNIPAM chain ends dehydrate and contract, enhancing hydrophobicity and making it easier to adsorb onto the oil-water interface to form a tight interfacial film, enhancing kinetic stability and maintaining the emulsified state. At low temperatures, the polymer dissolves hydrophilically and detaches from the interface, causing the interfacial film to be damaged and thermodynamic instability to dominate, leading to phase separation. In the 0.1 wt% system, comparing the emulsification effects of Example 2 with a low NIPAM addition amount and Example 11 with a high NIPAM addition amount, it is found that the latter performs better in terms of the uniformity of oil-water dispersion and interfacial stability. A high NIPAM content has more hydrophobic groups (NIPAM), providing stronger interfacial adsorption ability at high temperatures, forming a denser interfacial film, and improving the uniformity of oil-water dispersion. The interfacial coverage density of a low NIPAM content is insufficient, making it difficult to form an effective barrier, resulting in poor emulsification stability. In the low-concentration system of 0.01 wt%, although Example 11 is still better than Example 2, the oil and water phases do not separate completely after demulsification, indicating that the demulsification efficiency of NIPAM is limited by its effective coverage density at the interface. When the solution mass fraction decreases from 0.1 wt% to 0.01 wt%, the system can still maintain partial emulsification function, but an unemulsified aqueous phase appears at the bottom. As the solution mass fraction further decreases to 0.001 wt%, the emulsification efficiency drops sharply, confirming that the concentration of the surface-active polymer is significantly positively correlated with the emulsification performance. At a concentration of 0.1 wt%, the oil phase separates completely after the system is demulsified; while in the 0.01 wt% system, residual oil droplets remain after demulsification, and the interfacial response sensitivity needs to be improved by optimizing the molecular design. The thermosensitive property of NIPAM dynamically regulates the interfacial tension through the conformational changes of the molecular chain segments (shrinking at high temperatures and stretching at low temperatures). The synergistic effect of the two enables the high-concentration system (0.1 wt%) to achieve rapid and reversible emulsification-demulsification conversion under temperature stimulation.

[0131] It should be noted that in Figure 5 and Figure 7 , P4 represents the surface-active polymer obtained in Example 1, P8 represents the surface-active polymer obtained in Example 5, P9 represents the surface-active polymer obtained in Example 6, P10 represents the surface-active polymer obtained in Example 7, and P11 represents the surface-active polymer obtained in Example 8; in Figure 6 and Figure 8 , P-9 represents the surface-active polymer obtained in Example 2, P-11 represents the surface-active polymer obtained in Example 9, P-12 represents the surface-active polymer obtained in Example 10, and P-13 represents the surface-active polymer obtained in Example 11.

[0132] It should be noted that in Figure 11 and 12Among them, the upper part shows the test results at 65°C, and the lower part shows the test results at 25°C; from left to right are the oil-water systems composed of surfactant polymers with mass concentrations of 0.1 wt%, 0.01 wt%, and 0.001 wt% and paraffin.

[0133] In the present invention, when the molar ratio of N-isopropylacrylamide, acrylamide, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide, and the second functional monomer (AEOFM) is 1.5:0.8:0.16:0.04, the surface tension of the surfactant polymer P(NIPAM-AM-DMMPPS-AEOFM) is reduced to 40 mN / m, and the interfacial tension is further reduced to 10 -3 mN / m, breaking through the bottleneck of ultra-low interfacial tension and maintaining an ultra-low interfacial tension (<10 -3 mN / m) under simulated high-temperature (45°C) and high-salt (salinity > 20000 mg / L) conditions, solving the problem that traditional surfactants are prone to inactivation in high-salinity oil reservoirs, and being applicable to offshore oilfields or deep high-temperature reservoirs.

[0134] The surfactant polymer prepared in the present invention has temperature-responsive characteristics and can achieve the integrated functions of intelligent oil displacement and demulsification. At 65°C, it can form a stable emulsion through the dynamic balance of hydrophobic-hydrophilic, and quickly demulsify at 25°C. This characteristic makes it particularly suitable for steam flooding reservoirs or heavy oil thermal recovery processes: during the high-temperature steam injection stage, it can assist in emulsifying and reducing viscosity to improve oil displacement efficiency; during the low-temperature production stage, rapid oil-water separation can be achieved without additional demulsifiers, significantly reducing the use cost of chemical agents, meeting the requirements of the green transformation of oilfield development.

[0135] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a surface active polymer, characterized in that: include: The surface active functional monomer, N-isopropyl acrylamide, acrylamide, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl) ammonium hydroxide, an initiator and water are polymerized in the presence of a catalyst system to obtain the surface active polymer.

2. The preparation method according to claim 1, characterized in that: The surface active functional monomer is a first functional monomer or a second functional monomer; wherein the raw materials for preparing the first functional monomer include cardanol polyoxyethylene ether and allyl glycidyl ether; and the raw materials for preparing the second functional monomer include fatty alcohol polyoxypropylene polyoxyethylene ether and allyl glycidyl ether.

3. The preparation method according to claim 2, characterized in that: The first functional monomer is prepared by the following method: after mixing cardanol polyoxyethylene ether and potassium hydroxide, adjusting the temperature to 60-120° C., adding allyl glycidyl ether, and performing a ring-opening reaction to obtain a first surface active functional monomer; and / or, The second functional monomer is prepared by the following method: after mixing fatty alcohol polyoxypropylene polyoxyethylene ether and potassium hydroxide, adjusting the temperature to 90-110° C., adding allyl glycidyl ether, and subjecting to a ring-opening reaction, a surface active functional monomer is obtained; preferably, after the ring-opening reaction, the step of rotary evaporating the reaction liquid after the ring-opening reaction is also included.

4. The preparation method according to claim 1, characterized in that: The catalytic system is prepared by the following method: in a nitrogen atmosphere, CuBr, tris-(2-dimethylaminoethyl)amine and water are mixed and subjected to a disproportionation reaction to obtain a catalytic system; preferably, the molar ratio of the initiator, CuBr and tris-(2-dimethylaminoethyl)amine is 2:(2-4):

10.

5. The preparation method according to claim 1, characterized in that: In nitrogen atmosphere, including: (1) adding an initiator and N-isopropylacrylamide to water and mixing to obtain a mixed solution; (2) adding the mixed solution into the catalytic system to react and obtain a prepolymer system; (3) adding a surfactant functional monomer, acrylamide and [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl) ammonium hydroxide into water and mixing well to obtain a second mixed solution; and adding the second mixed solution into the prepolymer system to carry out a polymerization reaction to obtain the surfactant polymer.

6. The preparation method according to claim 1, characterized in that: The molar ratio of acrylamide, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl)ammonium hydroxide and the surface active functional monomer is 0.8:(0.04-0.16):(0.04-0.16); the molar amount of N-isopropylacrylamide accounts for 20%-80% of the sum of the molar amounts of the surface active functional monomer, N-isopropylacrylamide, acrylamide and [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl)ammonium hydroxide.

7. The preparation method according to claim 2, characterized in that: The molar ratio of acrylamide, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl) ammonium hydroxide and the first functional monomer is 0.8:0.08:0.12; the molar amount of N-isopropylacrylamide accounts for 80% of the sum of the molar amounts of the first functional monomer, N-isopropylacrylamide, acrylamide and [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl) ammonium hydroxide; or, The molar ratio of acrylamide, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl)ammonium hydroxide and the second functional monomer is 0.8:0.16:0.04; the molar amount of N-isopropylacrylamide accounts for 66.6% of the sum of the molar amounts of the second functional monomer, N-isopropylacrylamide, acrylamide and [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl)ammonium hydroxide.

8. The preparation method according to any one of claims 1 to 7, characterized in that: The initiator is an organic halide initiator containing a halogen terminal group; preferably, the initiator is at least one of methyl 2-bromopropionate, ethyl 2-bromopropionate, ethyl 2-bromophenylacetate, 2-bromoisobutyric acid, p-toluenesulfonyl chloride, 2-chloropropionamide, and α-bromoisobutyric acid; and / or, The molar amount of the initiator accounts for 0.4-1.6% of the total molar amount of the surface active functional monomer, N-isopropylacrylamide, acrylamide, and [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl)ammonium hydroxide.

9. A surface active polymer, characterized in that The method is prepared by any one of claims 1 to 8.

10. A use of the surface active polymer according to claim 9, characterized in that: It is used as an oil displacement agent in oil fields, preferably in offshore oil fields and deep high-temperature oil reservoirs.

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