阅读说明：本技术 基于动态共价键的响应性表面活性剂及其制备方法 (Dynamic covalent bond-based responsive surfactant and preparation method thereof ) 是由 苏鑫 黄小凌 冯玉军 于 2021-06-23 设计创作，主要内容包括：本发明公开了一种基于动态共价键的响应性表面活性剂及其制备方法。所述表面活性剂通过将3-氨基-1-丙磺酸钠与4-正癸氧基苯甲醛按照(0.5：1)～(1：0.5)的摩尔比混合溶于溶剂中,搅拌反应5～15min,然后去除溶剂,干燥后制备得到。所述表面活性剂在pH刺激下具有表面活性的可逆开关性,在碱性条件下,所述表面活性剂具有表面活性,在酸性条件下不具有表面活性,通过改变环境和体系的pH值能够实现表面活性的开关控制。本发明方法制备简单、成本低廉、绿色环保,解决传统响应性表面活性剂结构复杂、制备繁琐、成本高等问题。(The invention discloses a dynamic covalent bond-based responsive surfactant and a preparation method thereof. The surfactant is prepared by mixing 3-amino-1-propanesulfonic acid sodium salt and 4-n-decyloxy benzaldehyde according to a molar ratio of (0.5: 1) - (1: 0.5), dissolving in a solvent, stirring for reaction for 5-15 min, removing the solvent, and drying. The surfactant has reversible switching performance of surface activity under the stimulation of pH, has surface activity under alkaline conditions, does not have surface activity under acidic conditions, and can realize switching control of the surface activity by changing the pH value of the environment and the system. The method disclosed by the invention is simple to prepare, low in cost, green and environment-friendly, and solves the problems of complex structure, complex preparation, high cost and the like of the traditional responsive surfactant.)

1. A dynamic covalent bond-based responsive surfactant characterized by the following structural formula:

the surfactant has reversible switchability of surface activity under pH stimulation.

2. The method for preparing a dynamic covalent bond-based responsive surfactant according to claim 1, comprising:

mixing 3-amino-1-propanesulfonic acid sodium and 4-n-decyloxybenzaldehyde according to the molar ratio of (0.5: 1) to (1: 0.5), dissolving in a solvent, stirring for 5-15 min, removing the solvent, and drying to obtain the responsive surfactant.

3. The method of claim 2, wherein the solvent is at least one of methanol and ethanol.

4. The method according to claim 2, wherein the drying is carried out in a vacuum oven at 50 ℃ for 24 h.

5. The method of claim 2, wherein the reaction is stirred with magnetic stirring at 500 rpm.

6. Use of the surfactant of claim 1 in fields related to emulsion formation and breaking.

7. The use of claim 6, wherein the reversible process of emulsion preparation and breaking is achieved by changing the pH of the system, the emulsion is prepared by alkaline conditions, and the breaking is achieved by acidic conditions.

8. A composition, which is characterized by comprising sodium 3-amino-1-propanesulfonate and 4-n-decyloxybenzaldehyde, wherein the molar ratio of the sodium 3-amino-1-propanesulfonate to the 4-n-decyloxybenzaldehyde is (0.5: 1) to (1: 0.5).

9. Use of a composition according to claim 8 in the preparation of a pH-responsive surfactant.

The combined application of sodium 3-amino-1-propanesulfonate and 4-n-decyloxybenzaldehyde in the preparation of pH responsive surfactants.

Technical Field

The invention belongs to a novel surfactant, and particularly relates to a pH responsive surfactant based on a dynamic covalent bond.

Background

Emulsions are widely used in a variety of commercial products and industrial processes. For some applications, such as food storage and bitumen emulsification, where long term emulsification is required, it is important to maintain emulsion stability. However, in applications such as oil recovery, heavy oil transportation and emulsion polymerization, long-term emulsification is not required, only temporary emulsion stability is required, and the system is then demulsified. Typically, the system is broken by chemical means, such as the addition of demulsifiers, etc., or by physical means, such as mechanical demulsification, etc. However, such methods are often energy intensive or result in significant environmental pollution. Therefore, in order to avoid a large energy consumption and pollution, a kind of emulsion having responsiveness (opening and closing performance under an external stimulus) is required, and accordingly, a surfactant having responsiveness is in the spotlight.

The responsive surfactant can reversibly interconvert between active and inactive under external stimulus, such as pH change, CO₂The introduction of light, light stimulation, etc. However, the traditional responsive surfactant has more defects, such as complex structure of the surfactant, complicated synthesis process, long time, high cost and the like.

Disclosure of Invention

The invention aims to provide a responsive surfactant based on a dynamic covalent bond and a preparation method thereof aiming at the defects of the prior art, so that the surfactant which is simple to prepare, low in cost, green and environment-friendly and has pH responsiveness is obtained, and the problems of complex structure, complex preparation, high cost and the like of the traditional responsive surfactant are solved.

The invention provides a dynamic covalent bond-based responsive surfactant, which has the following structural formula:

the surfactant has reversible switchability (pH responsiveness) of surface activity under pH stimulation.

The reversible switchability means that the surfactant has surface activity under an alkaline condition and does not have surface activity under an acidic condition, and the on/off control of the surface activity can be realized by changing the environment or the pH value of the surfactant system.

The preparation method of the dynamic covalent bond-based responsive surfactant provided by the invention comprises the following steps:

mixing 3-amino-1-propanesulfonic acid sodium and 4-n-decyloxybenzaldehyde according to the molar ratio of (0.5: 1) to (1: 0.5), dissolving in a solvent, stirring for reaction for 5-15 min, removing the solvent, and drying to obtain the responsive surfactant.

In the above method, the solvent is at least one of methanol and ethanol.

In the above method, further, the drying is drying in a vacuum drying oven at 50 ℃ for 24 h.

In the above method, further, the reaction was stirred at 500rpm with magnetic stirring.

The preparation and pH response processes of the responsive surfactant are as follows:

the raw material is alkalescent after being dissolved in water and can generate Schiff base reaction, and the amino (NH) on the 3-amino-1-propanesulfonic acid sodium salt₂) Generates dynamic imine bond by condensation reaction with aldehyde group (CHO) on 4-n-decyloxybenzaldehyde. The obtained responsive surfactant is connected with 3-amino-1-propanesulfonic acid sodium and 4-n-decyloxy benzaldehyde through imine bond as a dynamic covalent bond, the 3-amino-1-propanesulfonic acid sodium is a hydrophilic end, and the 4-n-decyloxy benzaldehyde is a hydrophobic end, so that the surfactant has amphipathy, and the surfactant has activity; under acidic conditions, imine bonds are unstably decomposed into primary amines and aldehyde groups, dynamic covalent bonds are broken, and the surfactant loses emulsifying capacity. The imine bond of the dynamic covalent bond can be controlled to be broken or formed by utilizing the change of the pH value (the pH value is adjusted by utilizing sodium hydroxide and hydrochloric acid to control the generation and the breakage of the dynamic covalent bond), thereby achieving the purpose of closing or beatingThe purpose of surfactant activity is opened.

The invention provides the application of the surfactant in the fields related to emulsion formation and emulsion breaking, such as the application in the fields of petroleum exploitation, emulsion polymerization, thick oil gathering and transportation and the like, and the situation that the emulsion needs to be broken rapidly after the emulsion plays a role. Particularly in the field of oil exploitation, the addition of the emulsifier can reduce the viscosity of the thick oil, namely emulsification and viscosity reduction, so that the thick oil can be conveniently exploited and collected and transported, and the emulsified thick oil needs to be demulsified after collection and transportation, so that preparation is made for next refining. The pH responsive surfactant disclosed by the invention has the advantages that the emulsification demulsification process is reversible and simple, the emulsification demulsification process can be realized only by depending on the change of the pH value, the energy consumption is low, and the product is not easy to pollute. Therefore, the method has a wide application prospect in related fields such as oil exploitation and the like. When the emulsion breaking agent is applied, the reversible processes of emulsion preparation and emulsion breaking are realized by changing the pH value of a system, the emulsion is prepared under an alkaline condition, and the emulsion breaking is realized under an acidic condition.

The invention provides a composition, which comprises 3-amino-1-sodium propane sulfonate and 4-n-decyloxybenzaldehyde, wherein the molar ratio of the 3-amino-1-sodium propane sulfonate to the 4-n-decyloxybenzaldehyde is (0.5: 1) - (1: 0.5).

The invention provides application of the composition in preparing a pH-responsive surfactant.

The invention also provides the combined application of the sodium 3-amino-1-propanesulfonate and the 4-n-decyloxybenzaldehyde in the preparation of the pH responsive surfactant.

Compared with the prior art, the invention has the following beneficial effects:

1. the dynamic covalent bond-based responsive surfactant can complete the opening and closing of the surface activity through the change of the pH value of a system, has reversibility, and has great application potential in the field of reversible or one-time control of the formation and demulsification of emulsion.

2. The responsive surfactant has the following characteristics that when the surfactant is applied to an emulsion, compared with the traditional surfactant, the demulsification process is greatly simplified, the traditional physical or chemical demulsification is not needed, the demulsification cost is saved, the energy consumption is reduced, and meanwhile, the pollution caused by the demulsification process or follow-up process is reduced.

3. Compared with the traditional responsive polymer in preparation, the responsive surfactant disclosed by the invention has the advantages that two compounds forming the surfactant are both small molecules, can be directly purchased, are low in cost and simple to prepare, and can greatly reduce the production cost.

Drawings

FIG. 1 is a nuclear magnetic hydrogen spectrum (600MHz) of the surfactant prepared in example 1;

FIG. 2 is a local nuclear magnetic hydrogen spectrum for several cases: (a) 4-n-decyloxybenzaldehyde; (b) 4-n-decyloxybenzaldehyde + 3-amino-1-propanesulfonic acid sodium salt; (c) 4-n-decyloxybenzaldehyde, 3-amino-1-sodium propane sulfonate and hydrochloric acid.

Detailed Description

The invention is further illustrated by the following examples. It should be noted that the following examples are only for illustrating the present invention and should not be construed as limiting the scope of the present invention, and those skilled in the art can make certain insubstantial modifications and adaptations of the present invention based on the above disclosure and still fall within the scope of the present invention.

In the following examples, sodium 3-amino-1-propanesulfonate and 4-n-decyloxybenzaldehyde are both commercially available.

Example 1

Mixing 3-amino-1-propanesulfonic acid sodium salt and 4-n-decyloxybenzaldehyde according to the proportion of 1: 1, stirring and reacting for 10min at the rotating speed of 500rpm, then evaporating the methanol by using a rotary evaporator, and placing a product obtained after rotary evaporation in a vacuum drying oven at 50 ℃ for drying for 24h to obtain the dynamic covalent bond-based responsive surfactant.

FIG. 1 shows the nuclear magnetic hydrogen spectrum (600MHz) of the prepared surfactant.

FIG. 2 is a local nuclear magnetic hydrogen spectrum (showing absorption peak positions) in different cases. As can be seen from fig. 2(a), the absorption peak of aldehyde group of 4-n-decyloxybenzaldehyde was 9.84 ppm; as shown in fig. 2(b), the aldehyde absorption peak substantially disappeared after the addition of sodium 3-amino-1-propanesulfonate, and an absorption peak of imine bond appeared at δ ═ 8.21ppm, demonstrating that 4-n-decyloxybenzaldehyde reacts with sodium 3-amino-1-propanesulfonate to form a surfactant; as shown in fig. 2(c), after the addition of hydrochloric acid, the absorption peak of the imine bond disappeared, and the absorption peak of the methoxy group was newly formed at δ of 9.81ppm, which confirmed that the surfactant was decomposed again into 4-n-decyloxybenzaldehyde and sodium 3-amino-1-propanesulfonate in an acidic environment.

An emulsion was prepared using the surfactant described in example 1:

mixing paraffin oil and a surfactant aqueous solution (0.012mol/L) in a volume ratio of 1: 1, mixing, placing in a cell crusher, and performing ultrasonic treatment for 20 times (power 400W, working for 5s each time and intermittent operation for 5s) by using a 6mm probe to obtain the emulsion.

Verification of pH responsiveness of the emulsion: dynamic interfacial tension (IFT) of surfactants

The dynamic interfacial tension (IFT) between aqueous surfactant solutions and paraffin oil at different pH was determined using an interfacial rheometer. Aqueous surfactant solutions at different pH were placed in a syringe while paraffin oil was loaded into the cuvette. Adjusting and controlling the rotating speed to form a 3 mu L water drop in the paraffin oil, observing the change of the shape of the water drop in the paraffin oil through a CCD camera, measuring the dynamic IFT between the surfactant aqueous solution and the paraffin oil under different pH values, and adjusting the pH value by adopting a sodium hydroxide solution and hydrochloric acid in the test process.

And (3) testing results: when the pH is 7.82, the surfactant can reduce the IFT between oil (paraffin oil) and water to about 11.5mN/m within 10-15 min, which shows that the surfactant has higher interfacial activity; when the pH of the aqueous surfactant solution was lowered from 7.82 to 3.61, the IFT between oil and water was increased and maintained at about 31.9mN/m, which is similar to the IFT between the aqueous solution of sodium paraffin oil-3-amino-1-propanesulfonate and the aqueous solution of paraffin oil-4-n-decyloxybenzaldehyde. And after the pH value of the surfactant aqueous solution is increased from 3.61 to 7.82 again, the IFT value is reduced to about 11.5mN/m within 10-15 min, which shows that under the pH value, the Schiff base reaction is carried out on the 3-amino-1-propanesulfonic acid sodium and the 4-n-decyloxybenzaldehyde again to generate the surfactant with interfacial activity and dynamic imine bonds. The IFT test results demonstrate that by changing the pH, the surfactant can be made to interconvert between having interfacial activity and not having interfacial activity, i.e., it is pH-responsive, and that such switching is reversible. Meanwhile, when the emulsion containing the surfactant is at the pH of 3.61, the system separates oil from water and loses emulsification; and when the pH value is 7.82, the emulsion is reformed, stable and uniform.

Example 2

Mixing 3-amino-1-propanesulfonic acid sodium salt and 4-n-decyloxybenzaldehyde according to the weight ratio of 0.8: 1, stirring and reacting for 10min at the rotating speed of 500rpm, then evaporating the methanol by using a rotary evaporator, and placing a product obtained after rotary evaporation in a vacuum drying oven at 50 ℃ for drying for 24h to obtain the dynamic covalent bond-based responsive surfactant.

An emulsion was prepared using the surfactant described in example 2:

mixing paraffin oil and a surfactant aqueous solution (0.012mol/L) in a volume ratio of 1: 1, mixing, then placing in a probe (6mm) of a cell crusher, and carrying out ultrasonic treatment for 20 times (power 400W, working for 5s each time and intermittent operation for 5s) to obtain the emulsion.

Verification of pH responsiveness of the emulsion: dynamic interfacial tension (IFT) of surfactants

The dynamic interfacial tension (IFT) between aqueous surfactant solutions and paraffin oil at different pH was determined using an interfacial rheometer. Aqueous surfactant solutions at different pH were placed in a syringe while paraffin oil was loaded into the cuvette. Adjusting and controlling the rotating speed to form a 3 mu L water drop in the paraffin oil, observing the change of the shape of the water drop in the paraffin oil through a CCD camera, measuring the dynamic IFT between the surfactant aqueous solution and the paraffin oil under different pH values, and adjusting the pH value by adopting a sodium hydroxide solution and hydrochloric acid in the test process.

And (3) testing results: when the pH is 7.78, the surfactant can reduce the IFT between oil (paraffin oil) and water to about 13.7mN/m within 10-15 min, which shows that the surfactant has higher interfacial activity; when the pH of the aqueous surfactant solution was lowered from 7.78 to 3.63, the IFT between oil and water was increased and maintained at about 32.6mN/m, which is similar to the IFT between the aqueous solution of sodium paraffin oil-3-amino-1-propanesulfonate and the aqueous solution of paraffin oil-4-n-decyloxybenzaldehyde. And after the pH value of the surfactant aqueous solution is increased from 3.63 to 7.78 again, the IFT value is reduced to about 13.7mN/m within 10-15 min, which shows that under the pH value, the Schiff base reaction is carried out on the 3-amino-1-propanesulfonic acid sodium and the 4-n-decyloxybenzaldehyde again to generate the surfactant with the interfacial activity and the dynamic imine bond. The IFT test results demonstrate that by changing the pH, the surfactant can be made to interconvert between having interfacial activity and not having interfacial activity, i.e., it is pH-responsive, and that such switching is reversible. Meanwhile, when the emulsion containing the surfactant is at the pH of 3.63, the system separates oil from water and loses emulsification; and when the pH value is 7.78, the emulsion is reformed, stable and uniform.

Example 3

Mixing 3-amino-1-propanesulfonic acid sodium salt and 4-n-decyloxybenzaldehyde according to the proportion of 1: 1, stirring and reacting for 6min at the rotating speed of 500rpm, evaporating the methanol by using a rotary evaporator, and placing a product obtained after rotary evaporation in a vacuum drying oven at 50 ℃ for drying for 24h to obtain the dynamic covalent bond-based responsive surfactant.

An emulsion was prepared using the surfactant described in example 3:

mixing paraffin oil and a surfactant aqueous solution (0.012mol/L) in a volume ratio of 1: 1, mixing, then placing in a probe (6mm) of a cell crusher, and carrying out ultrasonic treatment for 20 times (power 400W, working for 5s each time and intermittent operation for 5s) to obtain the emulsion.

Verification of pH responsiveness of the emulsion: dynamic interfacial tension (IFT) of surfactants

The dynamic interfacial tension (IFT) between aqueous surfactant solutions and paraffin oil at different pH was determined using an interfacial rheometer. Aqueous surfactant solutions at different pH were placed in a syringe while paraffin oil was loaded into the cuvette. Adjusting and controlling the rotating speed to form a 3 mu L water drop in the paraffin oil, observing the change of the shape of the water drop in the paraffin oil through a CCD camera, measuring the dynamic IFT between the surfactant aqueous solution and the paraffin oil under the pH value, and adjusting the pH value by adopting a sodium hydroxide solution and hydrochloric acid in the test process.

And (3) testing results: when the pH value is 7.81, the surfactant can reduce the IFT between oil (paraffin oil) and water to about 12.5mN/m within 10-15 min, which shows that the surfactant has higher interfacial activity; when the pH of the aqueous surfactant solution was lowered from 7.81 to 3.59, the IFT between oil and water was increased and maintained at about 32.1mN/m, which is similar to the IFT between the aqueous solution of sodium paraffin oil-3-amino-1-propanesulfonate and the aqueous solution of paraffin oil-4-n-decyloxybenzaldehyde. And after the pH value of the surfactant aqueous solution is increased from 3.59 to 7.81 again, the IFT value is reduced to about 12.5mN/m within 10-15 min, which shows that under the pH value, the Schiff base reaction is carried out on the 3-amino-1-propanesulfonic acid sodium and the 4-n-decyloxybenzaldehyde again to generate the surfactant with interfacial activity and dynamic imine bonds. The IFT test results demonstrate that by changing the pH, the surfactant can be made to interconvert between having interfacial activity and not having interfacial activity, i.e., it is pH-responsive, and that such switching is reversible. Meanwhile, when the emulsion containing the surfactant is at the pH of 3.59, the system can separate oil from water and lose emulsification; when the pH value is 7.81, the emulsion is formed again, and is stable and uniform.