Preparation method of pH-responsive surfactant molecule with cyclic tertiary amine and wormlike micelle thereof

Abstract

The invention discloses a pH-responsive surfactant molecule with cyclic tertiary amine and a preparation method of wormlike micelles of the pH-responsive surfactant molecule, erucic acid and primary amine with cyclic tertiary amine substituent are used as raw materials to carry out amidation reaction to prepare a pH-responsive surfactant with cyclic tertiary amine, and the wormlike micelles of the pH-responsive surfactant molecule with cyclic tertiary amine are used for preparing the wormlike micelles of the wormlike micelles of the wormlike micelles of the wormlike micelles. Meanwhile, water is removed by adopting a high-temperature oil-water separation device in the amidation reaction process, so that the purpose of efficiently preparing the high-purity pH response surfactant is achieved; the obtained pH-responsive surfactant with the cyclic tertiary amine is blended with distilled water, and then acid is added to reduce the pH of the system, so that surfactant molecules are protonized, and wormlike micelles can be prepared; in addition, worm-like micelles formed under the acidic condition can be destroyed by adding alkali to adjust the pH of the system, so that the pH-responsive surfactant aqueous emulsion with the cyclic tertiary amine is obtained. The pH-responsive surfactant with the cyclic tertiary amine prepared by the invention has a wide application prospect in the fields of environmental protection, oilfield exploitation, chemicals and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of colloidal interface material synthesis, and particularly relates to a preparation method of a pH-responsive surfactant molecule having a cyclic tertiary amine and a worm-like micelle thereof. Background Art

[0002] Surfactants are a class of amphiphilic small molecules with both a hydrophilic head group and a hydrophobic tail chain. Under certain conditions, they can spontaneously organize into a variety of ordered structures, such as spheres, short rods, worms, and vesicles. Among them, worm-like micelles, as a model of a specific conformation, form linear supramolecular aggregates through the precise self-assembly process of surfactant molecules along a single dimension. When the concentration of surfactants in the system reaches a certain critical value, these worm-like micelles will intertwine with each other to build a three-dimensional spatial network, showing significant high viscoelasticity on a macro scale, and showing unique structural order and functional potential.

[0003] In recent years, research hotspots have gradually focused on intelligent worm-like micelle systems that are responsive to external stimuli (such as temperature, light and pH). Such systems can dynamically adjust their structure and performance, and show high adaptability and sensitivity to environmental changes. They are widely used in the fields of care products, oilfield fracturing fluids, cosmetics, drag reducers, drug release agents, template agents, drug dissolving agents, etc. In particular, high-temperature resistant worm-like micelle systems can be used as petroleum fracturing fluids in oil extraction, further highlighting the importance and practicality of scientific research in this field.

[0004] At present, there are relevant reports on the research of pH-responsive surfactants. For example, Chu Zonglin et al. (Chem. Commun., 2010, 46, 9028-9030.) used erucic acid and 3-dimethylaminopropylamine to synthesize a pH-responsive surfactant, which successfully achieved rapid and reversible conversion between worm-like micelles and spherical micelles, and showed a lower critical micelle concentration. Chinese patent CN 105566144 A discloses the synthesis of erucic acid amide propyl diethylamine surfactant molecules by changing the amine structure. Chinese patent CN108467721A discloses N, N-diethyl erucic acid ethyl amine, and adjusts the pH by acetic acid to obtain N, N-diethyl erucic acid ethyl amine acetate aqueous solution, and prepares a class of medium and high temperature clean fracturing fluids. Chinese patent CN 113583651A discloses an erucic acid amide propyl dihydroxyethyl tertiary amine, and the fracturing fluid prepared by it has good temperature resistance and sand carrying capacity. In summary, pH-responsive surfactant molecules synthesized from erucic acid and chain amines can prepare high-performance, highly viscoelastic fluids, which are particularly suitable for oil and gas production, showing great application potential. However, most of the above technologies are based on the transformation of 3-dimethylaminopropylamine (chain amine) and share similar structural features. There are no reports on pH-responsive surfactants synthesized from erucic acid and cyclic amines. Summary of the invention

[0005] In view of the technical problems existing in the background technology, the object of the present invention is to provide a method for preparing a pH-responsive surfactant molecule having a cyclic tertiary amine and a worm-like micelle thereof.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] The first aspect of the present invention is to provide a pH-responsive surfactant having a cyclic tertiary amine, the molecular structure of which is shown below:

[0008]

[0009] Wherein, R is a group having the following general formula:

[0010]

[0011] In the formula: X represents a straight-chain alkyl group having 1 to 5 carbon atoms; Y represents a cyclic tertiary amine substituent.

[0012] The second aspect of the present invention is to provide a method for preparing the above-mentioned pH-responsive surfactant having a cyclic tertiary amine, comprising the steps of: subjecting erucic acid and a primary amine having a cyclic tertiary amine substituent to an amidation reaction to obtain the pH-responsive surfactant having a cyclic tertiary amine.

[0013] Preferably, the amidation reaction temperature is 125-170° C., and the reaction time is 6-15 h.

[0014] Preferably, the molar ratio of erucic acid to the primary amine having a cyclic tertiary amine substituent is 1:1.

[0015] Preferably, during the amidation reaction, water removal treatment is also performed to further promote the reaction in the direction of a forward reaction.

[0016] Preferably, the equipment used for the water removal treatment is an oil-water separation device disclosed in Chinese patent CN 219209069 U.

[0017] Preferably, the primary amine having a cyclic tertiary amine substituent is selected from any one of the following substances:

[0018]

[0019] The third aspect of the present invention provides the use of the above pH-responsive surfactant having a cyclic tertiary amine in the preparation of worm-like micelles.

[0020] Preferably, the method for preparing worm-like micelles using a pH-responsive surfactant having a cyclic tertiary amine comprises the following steps:

[0021] S1. Add the above-mentioned pH-responsive surfactant having a cyclic tertiary amine into deionized water to prepare a pH-responsive surfactant aqueous solution with a mass concentration of 0.1% to 10%;

[0022] S2. Adding acid into the pH-responsive surfactant aqueous solution to adjust the pH of the solution system so that the surfactant molecules are protonated to form worm-like micelles.

[0023] Preferably, the acid can be an organic acid or an inorganic acid, for example, one or a combination of two or more of HCl, HNO3, H3BO3, H2SO4, H2CO3, H3PO4, HBr, formic acid, acetic acid, propionic acid, butyric acid, malonic acid, succinic acid and maleic acid, but is not limited to the above acids.

[0024] Preferably, the method further comprises: adding a base to the worm-like micelles obtained under acidic conditions to adjust the pH of the system, deprotonating the worm-like micelles to destroy the worm-like micelles, and then obtaining an aqueous emulsion of a pH-responsive surfactant having a cyclic tertiary amine.

[0025] Preferably, the base is a base commonly used in the art, such as one or a combination of two or more of NaOH, KOH, Ca(OH)2, Ba(OH)2, NaHCO3 and Na2CO3, but is not limited to the above bases.

[0026] The present invention has the following beneficial effects:

[0027] (1) The present invention uses erucic acid and a primary amine having a cyclic tertiary amine substituent as raw materials and performs an amidation reaction at a certain temperature to innovatively prepare a pH-responsive surfactant having a cyclic tertiary amine. By introducing a unique five-membered or six-membered heterocyclic spatial structure, the size of the hydrophilic head group in the surfactant molecule can be better controlled, thereby regulating the stacking parameters and realizing the directional design of the self-assembly morphology. At the same time, the strong nucleophilicity of the intracyclic heteroatoms (such as oxygen and nitrogen) in the molecular structure of the pH-responsive surfactant having a cyclic tertiary amine can enhance the reactivity of the molecule, create conditions for the introduction of functional groups, and enable the molecular structure to be flexibly adjusted and optimized according to specific application requirements, greatly enriching the possibility of functional customization.

[0028] (2) The cyclic tertiary amine pH-responsive surfactant prepared by the present invention is used to successfully prepare highly viscoelastic worm-like micelles. Since the hydrophobic tail chain in the molecular structure of the cyclic tertiary amine pH-responsive surfactant contains an unsaturated double bond, it is beneficial to improve the flexibility and water solubility of the surfactant. The experimental results show that the highly viscoelastic worm-like micelles exhibit fast response and low critical micelle concentration (critical micelles of the formed worm-like micelles), and a good viscosity-enhancing effect can be achieved with a minimum concentration of only 0.1%. Therefore, it has a high economic benefit, and thus significantly promotes the diversified development of cyclic tertiary amine pH-responsive surfactants.

[0029] (3) The pH-responsive surfactant with cyclic tertiary amine prepared by the present invention is sensitive and quick to respond. After adding acid or alkali and stirring evenly, the morphology can be quickly transformed. Moreover, surfactants with different pH response ranges can be designed by changing the structure of the cyclic tertiary amine substituent in the primary amine, so adaptive design can be carried out in practical applications.

[0030] (4) The present invention provides a complete process from the synthesis of surfactant molecules in the early stage to the preparation of pH-responsive micelles in the later stage, and has broad application prospects in the fields of environmental protection, oil field exploitation, and preparation of chemicals. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 This is the NMR spectrum of the pH-responsive surfactant having a cyclic tertiary amine synthesized in Example 1;

[0033] Figure 2 This is the NMR spectrum of the pH-responsive surfactant having a cyclic tertiary amine synthesized in Example 2;

[0034] Figure 3 This is the NMR spectrum of the pH-responsive surfactant having a cyclic tertiary amine synthesized in Example 3;

[0035] Figure 4 This is the NMR spectrum of the pH-responsive surfactant having a cyclic tertiary amine synthesized in Example 4;

[0036] Figure 5 This is a picture of worm-like micelles prepared using 1-(2-erucamidoethyl)piperidine in Experimental Example 1;

[0037] Figure 6The flow curve of the aqueous solution of 1-(2-erucic acid amidoethyl) piperidine with a mass fraction of 5% at different pH values ​​in Experimental Example 1;

[0038] Figure 7 The flow curve of the aqueous solution of 1-(2-erucic acid amide ethyl) pyrrolidine with a mass fraction of 5% at different pH values ​​in Experimental Example 2;

[0039] Figure 8 The flow curve of the aqueous solution of 4-(2-erucic acid amide ethyl)-morpholine with a mass fraction of 5% at different pH values ​​in Experimental Example 3;

[0040] Fig. 9 It is a general structural formula of a pH-responsive surfactant having a cyclic tertiary amine. DETAILED DESCRIPTION

[0041] In the following description, for the purpose of illustration rather than limitation, specific details such as specific system structures and technologies are provided to provide a thorough understanding of the embodiments of the present invention. However, it should be clear to those skilled in the art that the present invention may also be implemented in other embodiments without these specific details.

[0042] Example 1

[0043] Reference Fig. 9 , is a general structural formula of a cyclic tertiary amine pH-responsive surfactant, and the specific synthetic structural formula is 1-(2-erucic acid amide ethyl) piperidine as shown in the following formula (1):

[0044]

[0045] Take 0.1mol 1-(2-aminoethyl)piperidine, 0.1mol erucic acid (cis-n-docosahexaenoic acid) and 20mL toluene and place them in a reaction bottle, connect to a high-temperature oil-water separation device, set the oil bath temperature to 155°C, condense and reflux for 9h, stop the reaction, evaporate the toluene in the system, and obtain a brown product, namely 1-(2-erucic acid amidoethyl)piperidine. Its NMR spectrum is shown in Figure 1 .

[0046] Example 2

[0047] The synthetic structure is shown in the following formula (2) of a pH-responsive surfactant having a cyclic tertiary amine: 1-(2-erucic acid amide ethyl) pyrrolidine

[0048]

[0049] Take 0.1mol 1-(2-aminoethyl)pyrrolidine, 0.1mol erucic acid (cis-n-docosahexaenoic acid) and 20mL toluene and place them in a reaction bottle, connect to a high-temperature oil-water separation device, set the oil bath temperature to 155°C, reflux for 9h, stop the reaction, evaporate the toluene in the system, and the brown product obtained is 1-(2-erucic acid amide ethyl)pyrrolidine. Its NMR spectrum is shown in Figure 2 .

[0050] Example 3

[0051] The synthetic structure is shown in the following formula (3) of the pH-responsive surfactant having a cyclic tertiary amine: 1-(2-erucic acid amide propyl) pyrrolidine

[0052]

[0053] Take 0.1mol 1-(3-aminopropyl)pyrrolidine, 0.1mol erucic acid (cis-n-docosahexaenoic acid) and 20mL toluene and place them in a reaction bottle, connect to a high-temperature oil-water separation device, set the oil bath temperature to 155°C, condense and reflux for 10h, stop the reaction, evaporate the toluene in the system, and the brown product obtained is: 1-(2-erucic acid amide propyl) pyrrolidine. Its NMR spectrum is shown in Figure 3 .

[0054] Example 4

[0055] The synthetic structure of the pH-responsive surfactant is shown in the following formula (4): 4-(2-erucic acid amide ethyl)-morpholine

[0056]

[0057] Take 0.1mol 2-aminoethylmorpholine, 0.1mol erucic acid (cis-n-docosahexaenoic acid) and 20mL toluene and place them in a reaction bottle, connect to a high-temperature oil-water separation device, set the oil bath temperature to 155°C, reflux for 12h, stop the reaction, evaporate the toluene in the system, and the brown product obtained is 4-(2-erucic acid amide ethyl)-morpholine. Its NMR spectrum is shown in Figure 4 .

[0058] Test Example 1

[0059] 5 g of the pH-responsive surfactant prepared in Example 1, specifically 1-(2-erucic acid amide ethyl) piperidine, was added to 95 g of distilled water and stirred by a stirrer to prepare a pH-responsive surfactant aqueous solution with a mass concentration of 5%; concentrated hydrochloric acid was added to the solution system to adjust the pH of the system. It was observed that when the pH = 5.15, only 5 seconds later, the system was in a clear gel state. Figure 5The system was shear scanned at 25°C in steady-state mode to obtain the flow curves of a 5% aqueous solution of 1-(2-erucic acid amidoethyl)piperidine at different pH values ​​(see Figure 6 ),Depend on Figure 6 It can be seen that within a certain shear rate range, the viscosity of the system is maintained at ~10000 mPa·s and does not change with the increase of shear rate. When the shear rate exceeds the critical value, it exhibits shear thinning characteristics, proving that the surfactant forms worm-like micelles. Further, the pH of the solution system was adjusted with 4 mol / L NaOH solution, and it was observed that when pH = 6.52, the aqueous emulsion was milky white emulsion. Scanning in steady-state mode at 25°C showed that the system was a Newtonian fluid with a zero shear viscosity of ~1 mPa·s.

[0060] Test Example 2

[0061] 5 g of the pH-responsive surfactant prepared in Example 2, specifically 1-(2-erucic acid amide ethyl) pyrrolidine, was added to 95 g of distilled water and stirred by a stirrer to prepare a pH-responsive surfactant aqueous solution with a mass concentration of 5%; malonic acid was added to the system to adjust the pH of the solution system, and it was observed that when pH = 4.69, the system was in a clear gel state. The system was scanned in a steady-state mode at 25° C. to obtain the flow curve of an aqueous solution of 1-(2-erucic acid amide ethyl) pyrrolidine with a mass fraction of 5% at different pH values ​​(see Figure 7 ),Depend on Figure 7 It can be seen that within a certain shear rate range, the system viscosity is maintained at ~1400mPa·s and does not change with the increase of shear rate. When the shear rate exceeds the critical value, it exhibits shear thinning characteristics, proving that the surfactant forms worm-like micelles. Further, the pH of the solution system was adjusted with a 4mol / L NaOH solution, and it was observed that when pH = 7.85, the aqueous emulsion was milky white. Scanning in steady-state mode at 25°C measured that the system was a Newtonian fluid with a zero shear viscosity of ~1mPa·s.

[0062] Test Example 3

[0063] 5 g of the pH-responsive surfactant prepared in Example 4, specifically 4-(2-erucic acid amide ethyl)-morpholine, was added to 95 g of distilled water and stirred by a stirrer to prepare a pH-responsive surfactant aqueous solution with a mass concentration of 5%; concentrated hydrochloric acid was added to the system to adjust the pH of the system, and it was observed that when pH = 3.15, the system was in a clear gel state. The system was scanned in a steady-state mode at 25° C. to obtain the flow curve of a 5% mass fraction of 4-(2-erucic acid amide ethyl)-morpholine aqueous solution at different pH values ​​(see Figure 8 ),Depend on Figure 8It can be seen that within a certain shear rate range, the viscosity of the system is maintained at ~128000 mPa·s and does not change with the increase of shear rate. When the shear rate exceeds the critical value, it exhibits shear thinning characteristics, which proves that the surfactant forms worm-like micelles. Furthermore, the pH of the system is adjusted with 4 mol / L NaOH solution. When the pH is 4.60, the aqueous emulsion is milky white. Scanning in steady-state mode at 25°C shows that the system is a Newtonian fluid with a zero shear viscosity of ~1 mPa·s.

[0064] The present invention is not limited to the above-mentioned specific implementation modes. Various changes made by ordinary technicians in this field based on the above-mentioned concepts without creative work are all within the protection scope of the present invention.

Claims

1. A pH-responsive surfactant having a cyclic tertiary amine, characterized in that: Its molecular structure is shown in the following formula (I): Wherein, R is a group having the following general formula: In the formula: X represents a straight-chain alkyl group having 1 to 5 carbon atoms; Y represents a cyclic tertiary amine substituent.

2. A method for preparing a pH-responsive surfactant having a cyclic tertiary amine as claimed in claim 1, characterized in that: include: The pH-responsive surfactant having a cyclic tertiary amine is obtained by subjecting erucic acid to an amidation reaction with a primary amine having a cyclic tertiary amine substituent.

3. The method for preparing a pH-responsive surfactant having a cyclic tertiary amine according to claim 2, characterized in that: The temperature of the amidation reaction is 125-170° C., and the reaction time is 6-15 hours.

4. The method for preparing a pH-responsive surfactant having a cyclic tertiary amine according to claim 2, characterized in that: During the amidation reaction, water removal treatment is also performed.

5. The method for preparing a pH-responsive surfactant having a cyclic tertiary amine according to claim 2, characterized in that: The primary amine having a cyclic tertiary amine substituent is selected from any one of the following substances:

6. Use of the pH-responsive surfactant having a cyclic tertiary amine as claimed in claim 1 in the preparation of worm-like micelles.

7. The use according to claim 6, characterized in that: The method for preparing worm-like micelles by using a pH-responsive surfactant having a cyclic tertiary amine comprises the following steps: S1. Adding a pH-responsive surfactant having a cyclic tertiary amine into deionized water to prepare a pH-responsive surfactant aqueous solution having a mass concentration of 0.1% to 10%; S2. Adding acid into the pH-responsive surfactant aqueous solution to adjust the pH of the solution system so that the surfactant molecules are protonated to form worm-like micelles.

8. The use according to claim 7, characterized in that: The acid is one or a combination of two or more of HCl, HNO3, H3BO3, H2SO4, H2CO3, H3PO4, HBr, formic acid, acetic acid, propionic acid, butyric acid, malonic acid, succinic acid and maleic acid.

9. The use according to claim 7, characterized in that: Also includes: A base is added to the worm-like micelles obtained under acidic conditions to adjust the pH of the system and deprotonate the worm-like micelles to destroy the worm-like micelles, thereby obtaining an aqueous emulsion of a pH-responsive surfactant having a cyclic tertiary amine.

10. The use according to claim 9, characterized in that: The alkali is one or a combination of two or more of NaOH, KOH, Ca(OH)2, Ba(OH)2, NaHCO3 and Na2CO3.

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