A pH-responsive viscosifying polymer solution system and a method for preparing the same

Abstract

The application discloses a pH response tackifying polymer solution system, which comprises the following components in mass fraction: 1-10 parts of monomers; 114-198 parts of water; 0.001-0.01 parts of an initiator; and 0.01-0.36 parts of a cationic polymer, and discloses a preparation method of the pH response tackifying polymer solution system, which comprises the following steps: S1, preparation of a strong alkali response polymer; and S2, construction of the pH response tackifying polymer solution system. The application is suitable for the technical field of colloid chemistry, and based on the fact that the polymer with an ester group or an amide group forms an anionic polymer under strong alkali, and then the anionic polymer and the cationic polymer are electrostatically adsorbed to form a stable crosslinking system, the viscosity of the polymer solution is increased, the solution viscosity change is realized under strong alkali pH control, the alkali response mechanism is a powerful supplement and improvement to the construction idea of the current pH response system, the components are simple, the process is simple, and the cost is low.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of colloid chemistry, and particularly relates to a pH response thickening polymer solution system and a preparation method thereof. BACKGROUND

[0002] Intelligent polymer solution can realize the transition from low-viscosity solution state to high-viscosity gel state under specific environmental conditions, and is widely used in the fields of drug delivery, oil exploitation, biosensors and the like. The pH stimulus response type water-soluble polymer refers to a polymer containing acid or alkali groups (such as carboxylic acid or amine group) which are easy to hydrolyze or protonate on a side chain. When the external pH changes, the degree of dissociation of these groups changes accordingly, thereby causing the change of the charge of the polymer chain, resulting in the change of the conformation of the polymer chain. For example, the pH stimulus response type water-soluble polymer changes from the collapse state to the extension state, which is the result of the ionization of the side chain group leading to the increase of the electrostatic repulsion, thereby destroying the hydrogen bond interaction between the polymer chains and causing the change of the osmotic pressure of the counterions. According to the difference of the pH response group, it can be divided into two types of anion and cation. The ionizable group of the anion type pH stimulus response intelligent water-soluble polymer is generally -COOH. The most widely studied is polyacrylic acid (PAA) or polymethacrylic acid (PMAA) and their derivatives. For example, Tsitsilianis et al. (Macromol. Rapid Commun. 2008, 29, 130) prepared a polymer solution with pH response based on the copolymerization of acrylic acid and methyl methacrylate, and the pH control range was 1.5-4.5. When the pH of the system was 1.5, the polyacrylic acid was not ionized, and the solution state was less than 10 mPa·s. When the pH of the system was controlled to 4.5, the side chain of the polyacrylic acid was ionized into negatively charged carboxylate, the water absorption was enhanced, the hydrophilic layer was thickened, and the system became a gel state with a viscosity as high as 4000 mPa·s. The ionizable group of the cation type pH stimulus response intelligent water-soluble polymer is generally basic primary amine, secondary amine, tertiary amine and the like, and the pH response mainly comes from the protonation of the amine group. Feng et al. (Chem. Commun., 2010, 46, 9028) introduced a tertiary amine group to synthesize erucyl amide propyl dimethylamine, and compounded it with sodium maleate to prepare an assembled water-soluble solution with pH response. The pH control range of the system was 2-8. When the pH was 8, the system was in a low-viscosity solution state, and when the pH was 2, the tertiary amine was protonated to become a quaternary ammonium salt, which was electrostatically adsorbed with the maleate anion and further assembled into a high-viscosity state, with a viscosity as high as 100000 mPa·s.

[0003] The pH response groups mainly focus on carboxylic acid or amino, and the types are relatively single; and the mechanism of realizing pH-induced responsiveness is limited to the change of hydrophilicity and hydrophobicity of functional groups, and new pH response mechanisms are urgently needed. In addition, researchers focus on pH response polymer solutions in the pH range from strong acid to neutral acid response polymer solutions, and weak acid to weak alkaline response polymer solutions, and there is no report on the study of polymer solution thickening induced by strong alkaline environment. It is an important supplement to develop strong alkali response polymer solution with pH greater than 10 for pH response solution. For some special operations, such as the demand for intelligent profile control agent in the local strong alkaline formation formed by alkali flooding, it is of great significance to develop polymer aqueous solution with strong alkali-induced viscosity change. SUMMARY

[0004] The purpose of the present application is to overcome the defects of the prior art, and provide a pH response thickening polymer solution system and a preparation method thereof.

[0005] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0006] A pH response thickening polymer solution system and a preparation method thereof, comprising the following components in mass fraction:

[0007] 1-10 parts of monomer;

[0008] 114-198 parts of water;

[0009] 0.001-0.01 parts of initiator;

[0010] 0.01-0.36 parts of cationic polymer.

[0011] Preferably, the monomer is poly(ethylene glycol) 6～16 methacrylate, poly(ethylene glycol) 6～16 hydroxyl-terminated acrylate, acryloyloxyethyl trimethyl ammonium chloride, acrylamide, dimethylaminopropyl methacrylamide.

[0012] Preferably, the cationic polymer is one of polyacryloyl ethyl trimethyl ammonium chloride and polydiethyl diallyl ammonium chloride.

[0013] A preparation method of a pH response thickening polymer solution system is also disclosed, comprising the following steps:

[0014] S1. Preparation of strong alkali response polymer;

[0015] S2. Construction of pH response thickening polymer solution system.

[0016] Preferably, in the step S1, the preparation method of the strong alkali response polymer comprises:

[0017] The formula amount of monomer is placed in a heating container, 20-100 parts by mass of water is added, heated and stirred, 0.001-0.01 parts by mass of initiator is added, the product is settled with an organic solvent after reaction for 6-12 hours, and dried to obtain a strong base responsive polymer.

[0018] Preferably, the preparation process of the strong base responsive polymer is as follows:

[0019]

[0020] Wherein, A is a monomer, B is an initiator, and C is a strong base responsive polymer.

[0021] Preferably, the heating temperature is 50-90℃, and the stirring speed is 200-500rpm.

[0022] Preferably, in the step S2, the construction of the pH responsive thickening polymer solution system comprises:

[0023] 0.1-5 parts by mass of strong base responsive polymer, 94-98 parts by mass of water and 0.01-0.36 parts by mass of cationic polymer are placed in a reaction container, stirred until the solid is completely dissolved, to obtain a strong base responsive polymer dilute solution, a strong base is added to the system to adjust the pH to 10-14, to obtain a pH responsive thickening polymer solution system.

[0024] Preferably, the stirring speed is 300-1500rpm.

[0025] Preferably, the response process is as follows:

[0026]

[0027] Wherein, C is a strong base responsive polymer, and D is a cationic polymer.

[0028] In summary, due to the adoption of the above technical solutions, the application has the following advantages:

[0029] In the application, based on the ester group or amide group polymer forming an anionic polymer under strong base, and then the anion and cation polymer occurring electrostatic adsorption, a stable crosslinking system is formed, the polymer solution viscosity is increased, the strong alkaline pH controlled solution viscosity change is realized, that is, the pH responsive polymer aqueous solution;

[0030] In the application, the alkaline response mechanism is a powerful supplement and improvement to the current pH response system construction idea, the components of the pH responsive thickening polymer solution system are simple, only the prepared polymer is added to prepare a solution to obtain a strong base responsive polymer aqueous solution, the process is simple and the cost is low. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 is a flow chart of a preparation method of a pH-responsive thickening polymer solution system according to the present application;

[0032] Figure 2 is a GPC spectrum of the polymer involved in Example 7;

[0033] Figure 3 is a macroscopic photo of the pH-responsive polymer aqueous solution system involved in Example 7 at different pH values;

[0034] Figure 4 is the viscosity of the pH-responsive polymer aqueous solution system involved in Example 7 at different pH values;

[0035] Figure 5 is an infrared spectrum of the polymer involved in Example 7;

[0036] Figure 6 is a macroscopic photo of the polymer aqueous solution system involved in Examples 8, 9, 10, and 11 at pH = 13;

[0037] Figure 7 is the viscosity of the polymer aqueous solution system involved in Examples 8, 9, 10, and 11 at pH = 13;

[0038] Figure 8 is a SEM photo of the polymer aqueous solution involved in Example 11 at pH = 8 and pH = 13;

[0039] Figure 9 is the viscosity change of the polymer solution involved in Example 12 at different pH values;

[0040] Figure 10 is a macroscopic photo of the pH-responsive polymer aqueous solution system involved in Example 13 at different pH values;

[0041] Figure 11 is the rheological test data of the system after pH-induced thickening involved in Example 13. DETAILED DESCRIPTION

[0042] The specific embodiments of a pH-responsive thickening polymer solution system and a preparation method thereof according to the present application are further described below in conjunction with the accompanying drawings. Figures 1-11 The specific embodiments of a pH-responsive thickening polymer solution system and a preparation method thereof according to the present application are further described below in conjunction with the accompanying drawings.

[0043] Example 1:

[0044] This embodiment gives a specific embodiment of a pH-responsive thickening polymer solution system, which comprises the following components by mass fraction:

[0045] 1 part of monomer;

[0046] 114 parts of water;

[0047] 0.001 part of initiator;

[0048] 0.01 part of cationic polymer.

[0049] Further, the monomer is an ester group or amide group bearing polymer.

[0050] Further, the monomer is one of polyethylene glycol 6 methacrylate, polyethylene glycol 6 hydroxyl-terminated acrylate, acryloyloxyethyl trimethyl ammonium chloride, acrylamide, dimethylamino propyl methacrylamide.

[0051] Further, the cationic polymer is one of polyacryloyl oxyethyl trimethyl ammonium chloride, polydiethyl diallyl ammonium chloride.

[0052] Example 2:

[0053] This example gives a specific embodiment of a pH responsive tackifying polymer solution system, which includes the following components by mass fraction:

[0054] 5 parts of monomer;

[0055] 150 parts of water;

[0056] 0.005 parts of initiator;

[0057] 0.18 parts of cationic polymer.

[0058] Further, the monomer is an ester group or amide group bearing polymer.

[0059] Further, the monomer is polyethylene glycol 11 methacrylate.

[0060] Further, the cationic polymer is polyacryloyl oxyethyl trimethyl ammonium chloride.

[0061] Example 3:

[0062] This example gives a specific embodiment of a pH responsive tackifying polymer solution system, which includes the following components by mass fraction:

[0063] 10 parts of monomer;

[0064] 198 parts of water;

[0065] 0.01 parts of initiator;

[0066] 0.36 parts of cationic polymer.

[0067] Further, the monomer is an ester group or amide group polymer.

[0068] Further, the monomer is polyethylene glycol 16 Hydroxyl-terminated acrylate.

[0069] Further, the cationic polymer is polydimethyl diallyl ammonium chloride.

[0070] Example 4:

[0071] This embodiment gives a specific embodiment of a preparation method of a pH-responsive thickening polymer solution system, as shown in Figure 1 The preparation method comprises the following steps:

[0072] S1. Preparation of a strong base-responsive polymer;

[0073] S2. Construction of a pH-responsive thickening polymer solution system.

[0074] Further, in the step S1, the preparation method of the strong base-responsive polymer comprises:

[0075] The formula amount of monomer is placed in a heating container, 20 parts by mass of water is added, heated and stirred, 0.001 parts by mass of initiator is added, and after 6 hours of reaction, the product is settled with an organic solvent, dried, and a strong base-responsive polymer is obtained.

[0076] Further, the preparation process of the strong base-responsive polymer is:

[0077]

[0078] Wherein, A is a monomer, B is an initiator, and C is a strong base-responsive polymer.

[0079] Further, the heating temperature is 50°C, and the stirring speed is 200 rpm.

[0080] Further, in the step S2, the construction of the pH-responsive thickening polymer solution system comprises:

[0081] 0.1 parts by mass of strong base-responsive polymer, 94 parts by mass of water, and 0.01 parts by mass of cationic polymer are placed in a reaction container, stirred until the solid is completely dissolved, a strong base-responsive polymer dilute solution is obtained, strong base is added to the system to adjust the pH to 10, and a pH-responsive thickening polymer solution system is obtained.

[0082] Further, the stirring speed is 300 rpm.

[0083] Further, the response process is as follows:

[0084]

[0085] wherein C is a strong base responsive polymer, and D is a cationic polymer.

[0086] Example 5:

[0087] This embodiment gives a specific implementation of a preparation method of a pH responsive tackifying polymer solution system, as shown in Figure 1 , including the following steps:

[0088] S1. Preparation of a strong base responsive polymer;

[0089] S2. Construction of a pH responsive tackifying polymer solution system.

[0090] Further, in the step S1, the preparation method of the strong base responsive polymer includes:

[0091] The formula amount of monomer is placed in a heating container, 60 parts by mass of water is added, heated and stirred, 0.005 parts by mass of initiator is added, and after 9h of reaction, the product is settled with an organic solvent, dried, and the strong base responsive polymer is obtained.

[0092] Further, the preparation process of the strong base responsive polymer is:

[0093]

[0094] wherein A is a monomer, B is an initiator, and C is a strong base responsive polymer.

[0095] Further, the heating temperature is 70°C, and the stirring speed is 350 rpm.

[0096] Further, in the step S2, the construction of the pH responsive tackifying polymer solution system includes:

[0097] 2.5 parts by mass of the strong base responsive polymer, 96 parts by mass of water, and 0.18 parts by mass of the cationic polymer are placed in a reaction container, stirred until the solid is completely dissolved, a strong base responsive polymer dilute solution is obtained, a strong base is added to the system to adjust the pH to 12, and a pH responsive tackifying polymer solution system is obtained.

[0098] Further, the stirring speed is 900 rpm.

[0099] Further, the response process is as follows:

[0100]

[0101] wherein C is a strong base responsive polymer, and D is a cationic polymer.

[0102] Example 6:

[0103] The embodiment provides a preparation method of a pH-responsive thickening polymer solution system, and specifically comprises the following steps: Figure 1

[0104] S1, preparing a strong-alkali-responsive polymer;

[0105] S2, constructing the pH-responsive thickening polymer solution system.

[0106] Further, in the step S1, the preparation method of the strong-alkali-responsive polymer comprises the following steps:

[0107] The formula amount of monomers is placed in a heating container, 100 parts by mass of water is added, heating and stirring are conducted, 0.01 parts by mass of an initiator is added, and after 12 hours of reaction, the product is settled by using an organic solvent and dried to obtain the strong-alkali-responsive polymer.

[0108] Further, the preparation process of the strong-alkali-responsive polymer is as follows:

[0109]

[0110] A is a monomer, B is an initiator, and C is a strong-alkali-responsive polymer.

[0111] Further, the heating temperature is 90 DEG C, and the stirring speed is 500 rpm.

[0112] Further, in the step S2, the construction of the pH-responsive thickening polymer solution system comprises the following steps:

[0113] 5 parts by mass of the strong-alkali-responsive polymer, 98 parts by mass of water and 0.36 parts by mass of a cationic polymer are placed in a reaction container, stirring is conducted until the solid is completely dissolved, a strong-alkali-responsive polymer dilute solution is obtained, a strong alkali is added to the system to adjust the pH to 14, and a pH-responsive thickening polymer solution system is obtained.

[0114] Further, the stirring speed is 1500 rpm.

[0115] Further, the response process is as follows:

[0116]

[0117] C is a strong-alkali-responsive polymer, and D is a cationic polymer.

[0118] Embodiment 7

[0119] The embodiment discloses a preparation method of a pH-responsive thickening polymer solution system, and comprises the following steps:

[0120] ​(1) Take 10 g of acrylamide in a 100 mL three-necked flask, add 40 g of water, and drop 0.3 wt% AIBI aqueous solution at 60°C and 250 rpm. After 8 h of reaction, the polymer solution is precipitated with ethanol, dried, and the polyacrylamide solid is obtained. Figure 2 The results of gel permeation chromatography test show that the molecular weight of the synthesized polyacrylamide is 3.29 million.

[0121] (2) 2 parts by mass of the above polyacrylamide, 97.64 parts by mass of water, and 0.36 parts by mass of polydimethyl diallyl ammonium chloride with a molecular weight of 150,000 are placed in a sample bottle, and stirred at 1000 rpm until the solids are completely dissolved. A polymer solution is prepared. The pH of the system is measured to be 8. Then the pH of the system is adjusted to 13 with sodium hydroxide solution to obtain the thickened polymer aqueous solution. The macroscopic change is as shown in Figure 3 The initial state is a clear and transparent low-viscosity solution, and the system becomes a white slurry after being adjusted to strong alkaline. The viscosity of the system is tested by rheological viscosity test, and the results are as shown in Figure 4 When the pH is 8, the viscosity of the system is 39.9 mPa·s, and after adjusting the pH of the system to 13, the viscosity of the system increases significantly to 629 mPa·s. Next, the strong base-induced thickening process is characterized by infrared and the mechanism is explained, and the results are as shown in Figure 5 The infrared peak at 3423 cm-1 is the N-H stretching vibration peak of amide, confirming the presence of PAM component; the infrared peak at 1050 cm-1 is the C-N stretching vibration peak, confirming the presence of PDMDAAC component; and 1650 cm-1 is the characteristic peak of carboxylate, confirming that after adding strong base to the system, the amide bond is hydrolyzed to produce carboxylate anion, and associates with the quaternary ammonium salt cation component of PDMDAAC.

[0122] Example 8

[0123] The present embodiment discloses a method for preparing a pH-responsive thickening polymer solution system, comprising the following steps:

[0124] (1) Consistent with Example 7, take 10 g of acrylamide in a 100 mL three-necked flask, add 40 g of water, and drop 0.3 wt% AIBI aqueous solution at 60°C and 250 rpm. After 8 h of reaction, the polymer solution is precipitated with ethanol, dried, and the polyacrylamide solid is obtained.

[0125] (2) 2 parts by mass of the above polyacrylamide, 97.68 parts by mass of water, and 0.32 parts by mass of polydimethyl diallyl ammonium chloride with a molecular weight of 150,000 are placed in a sample bottle, and stirred at 1000 rpm until the solids are completely dissolved. A clear and transparent polymer solution is prepared, and the pH of the system is measured to be 8.1. The pH of the system is adjusted to 13 with sodium hydroxide solution to obtain the thickened white polymer sol, and the macroscopic change is asFigure 6 The rheological test results are shown in Table 1. Figure 7 As shown in Table 1, the viscosity of the system is 40 mPa-s when the pH is 8, and the viscosity of the system increases to 540 mPa-s after the pH of the system is adjusted to 13.

[0126] Example 9

[0127] The present example discloses a method for preparing a pH-responsive thickened polymer solution system, comprising the following steps:

[0128] (1) 10 g of acrylamide was weighed into a 100 mL three-necked flask, 40 g of water was added, and 0.3 wt% of an AIBI aqueous solution was added dropwise at a rotation speed of 250 rpm and 60°C. After 8 h of reaction, the polymer solution was precipitated with ethanol and dried to obtain a polyacrylamide solid.

[0129] (2) 2 parts by mass of the above polyacrylamide, 97.72 parts by mass of water, and 0.28 parts by mass of polydimethyl diallyl ammonium chloride with a molecular weight of 150,000 were placed in a sample bottle and stirred at a speed of 1000 rpm until the solids were completely dissolved. A polymer solution was prepared. The pH of the system was measured to be 8. The pH of the system was adjusted to 13 with a sodium hydroxide solution to obtain a thickened polymer aqueous solution. The rheological test results are shown in Table 1. Figure 7 As shown in Table 1, the viscosity of the system is 40 mPa-s when the pH is 8, and the viscosity of the system increases to 450 mPa-s after the pH of the system is adjusted to 13.

[0130] Example 10

[0131] The present example discloses a method for preparing a pH-responsive thickened polymer solution system, comprising the following steps:

[0132] (1) 10 g of acrylamide was weighed into a 100 mL three-necked flask, 40 g of water was added, and 0.3 wt% of an AIBI aqueous solution was added dropwise at a rotation speed of 250 rpm and 60°C. After 8 h of reaction, the polymer solution was precipitated with ethanol and dried to obtain a polyacrylamide solid.

[0133] (2) 2 parts by mass of the above polyacrylamide, 97.76 parts by mass of water, and 0.24 parts by mass of polydimethyl diallyl ammonium chloride with a molecular weight of 150,000 were placed in a sample bottle and stirred at a speed of 1000 rpm until the solids were completely dissolved. A polymer solution was prepared. The pH of the system was measured to be 8.04. Then the pH of the system was adjusted to 13 with a sodium hydroxide solution to obtain a thickened polymer aqueous solution. The rheological test results are shown in Table 1. Figure 7 As shown in Table 1, the viscosity of the system is 40 mPa-s when the pH is 8, and the viscosity of the system increases to 416 mPa-s after the pH of the system is adjusted to 13.

[0134] Example 11

[0135] The present embodiment discloses a method for preparing a pH-responsive thickening polymer solution system, comprising the following steps:

[0136] (1) In accordance with Example 7, 10 g of acrylamide was weighed into a 100 mL three-necked flask, 40 g of water was added, and 0.3 wt% of an AIBI aqueous solution was added dropwise at a rotation speed of 60°C and 250 rpm. After 8 h of reaction, the polymer solution was precipitated with ethanol and dried to obtain a polyacrylamide solid.

[0137] (2) 2 parts by mass of the above polyacrylamide, 97.80 parts by mass of water, and 0.20 parts by mass of polydimethyl diallyl ammonium chloride with a molecular weight of 150,000 were placed in a sample bottle and stirred at a speed of 1000 rpm until the solids were completely dissolved. A polymer solution was prepared. The pH of the system at this time was measured to be 8.07. Then the pH of the system was adjusted to 13 with a sodium hydroxide solution to obtain a thickening polymer aqueous solution. The rheological test results are shown in Figure 7 As shown, the viscosity of the system was 40 mPa·s when the pH was 8, and after adjusting the pH of the system to 13, the viscosity increased to 400 mPa·s. The response process was characterized by scanning electron microscopy, as shown in Figure 8 As shown, the polymer solution at a pH of 8 exhibited a typical liquid film state. After adjusting the pH to 13, the associated gel system exhibited a clear crosslinked network, revealing the internal mechanism of the viscosity change of the pH-regulated system.

[0138] Example 12

[0139] The present embodiment tests the effect of salinity on the response performance of a strong alkali-responsive polymer aqueous solution. The polyacrylamide used is prepared in Example 7, and the cationic polymer used is consistent with the polydimethyl diallyl ammonium chloride of Example 7. The steps are as follows:

[0140] Five bottles of mixed solutions containing 2 parts by mass of polyacrylamide and 97.64-97.80 parts by mass of water were prepared and placed in sample bottles, and then 0.20 parts by mass, 0.24 parts by mass, 0.28 parts by mass, 0.32 parts by mass, and 0.36 parts by mass of polydimethyl diallyl ammonium chloride were added to the sample bottles, respectively, and stirred at a speed of 1000 rpm until the solids were completely dissolved. 0.25 parts by mass of sodium chloride solid was additionally added to each bottle and stirred at a speed of 1000 rpm until the solids were completely dissolved. The pH of the system at this time was measured to be about 8. Then the pH of the system was adjusted to 13 with a sodium hydroxide solution, and the corresponding performance was observed. The rheological test results are shown in Figure 9As shown in the figure, when the pH is 8, the system viscosity of the 5 groups of solutions is about 28 mPa·s, and after adjusting the system pH to 13, the system viscosity increases to 310 mPa·s, 344 mPa·s, 398 mPa·s, 414 mPa·s and 504 mPa·s respectively with the increase of polydimethyl diallyl ammonium chloride. That is to say, in the environment of 2500 mineralization, the strong alkali stimulus response described in the application can still construct an associated crosslinked network. However, compared with Figure 7 , the viscosity after response decreases, which shows that the addition of NaCl can affect the thickness of the hydration layer of the polymer solution, partially inhibit the association of carboxylate and quaternary ammonium salt cations, and cause a slight decrease in the physical crosslinking density.

[0141] Example 13

[0142] The present embodiment discloses a preparation method of a pH response thickening polymer solution system, comprising the following steps:

[0143] (1) 10 g of poly(ethylene glycol) 8 methacrylate is weighed in a 100 mL three-necked flask, 40 g of water is added, and 0.4 wt% of APS aqueous solution is added dropwise at 60°C and 250 rpm. After 8 h of reaction, the polymer solution is precipitated with ethanol and dried to obtain a polyacrylamide solid.

[0144] (2) 2 parts by mass of the above poly(ethylene glycol) 8 methacrylate homopolymer, 97.80 parts by mass of water and 0.36 parts by mass of polyacryloyloxyethyltrimethylammonium chloride with a molecular weight of 250,000 are placed in a sample bottle, and stirred at a speed of 800 rpm until the solid is completely dissolved to prepare a polymer solution. The pH of the system at this time is measured to be 7.6. Then the pH of the system is adjusted to 13 with sodium hydroxide solution to obtain a thickened polymer aqueous solution.

[0145] The macroscopic photo of the response process is shown in Figure 9 , the initial state is a low-viscosity transparent solution, and after adjusting the pH to 13, the system becomes a white gelatinous state that can be dragged. The rheological test of the thickened product is shown in Figure 11 . When the shear amplitude is within 90%, the storage modulus is greater than the loss modulus, showing a typical gel state, and the modulus can be as high as 52000 mPa.

[0146] Working principle: as shown in Figures 1-11 , strong alkali induces the hydrolysis of ester or amide groups to produce anions, which physically crosslink with the cations in the system based on electrostatic adsorption. The formation of the crosslinked network brings about the increase of the system viscosity. The alkali response mechanism described in the present patent is a powerful supplement and improvement to the current construction idea of pH response system. The components of the pH response polymer aqueous solution are simple, only the polymer prepared in steps S1 and S2 is added to prepare a solution to obtain a strong alkali response polymer aqueous solution, which is simple in process and low in cost.

[0147] The above description is further detailed in connection with specific preferred embodiments of the application, and it is not to be construed that the specific implementation of the application is limited to these descriptions. For those skilled in the art of the present application, without departing from the concept of the present application, a number of simple deductions or substitutions can be made, and all of them should be considered as falling within the protection scope of the present application.

Claims

1. A pH-responsive viscosifying polymer solution system, characterized in that, By mass fraction, comprising the following components: 1-10 parts of monomer; 114-198 parts of water; 0.001-0.01 parts of initiator; 0.01-0.36 parts of cationic polymer; said monomer is poly(ethylene glycol) 6～16 methacrylate, poly(ethylene glycol) 6～16 one of hydroxyl-terminated acrylate, acrylamide, dimethylaminopropyl methacrylamide; The cationic polymer is one of polyacryloxyethyl trimethyl ammonium chloride and polydiethyl diallyl ammonium chloride; The preparation method of the pH-responsive thickening polymer solution system comprises the following steps: S1. Preparation of strong base-responsive polymer; S2. Construction of pH-responsive thickening polymer solution system; In the step S1, the preparation method of the strong base-responsive polymer comprises: Placing the formula amount of monomer in a heating container, adding 20-100 parts by mass of water, heating and stirring, adding 0.001-0.01 parts by mass of initiator, and after 6-12 hours of reaction, the product is settled with an organic solvent, dried, and the strong base-responsive polymer is obtained; The preparation process of the strong base-responsive polymer is as follows: Wherein, A is monomer, B is initiator, and C is strong base-responsive polymer; In the step S1, the heating temperature is 50-90℃, and the stirring speed is 200-500 rpm; In the step S2, the construction of the pH-responsive thickening polymer solution system comprises: Placing 0.1-5 parts by mass of strong base-responsive polymer, 94-98 parts by mass of water and 0.01-0.36 parts by mass of cationic polymer in a reaction container, stirring until the solid is completely dissolved, obtaining a strong base-responsive polymer dilute solution, adding strong base to the system to adjust the pH to 10-14, and obtaining a pH-responsive thickening polymer solution system.

2. The pH-responsive, viscosity-increasing polymer solution system according to claim 1, characterized in that In the step S2, the stirring speed is 300-1500 rpm.

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