CN114539536A

CN114539536A - Preparation method and application of perfluoropolyether surfactant containing amide bonds

Info

Publication number: CN114539536A
Application number: CN202210150337.5A
Authority: CN
Inventors: 水玲玲; 姚纪源; 金名亮
Original assignee: South China Normal University
Current assignee: South China Normal University
Priority date: 2022-02-18
Filing date: 2022-02-18
Publication date: 2022-05-27
Anticipated expiration: 2042-02-18
Also published as: CN114539536B

Abstract

Discloses a preparation method of perfluoropolyether surfactant containing amide bonds, which comprises the following steps: dissolving perfluorocarboxylic acid polyether in a solvent, and mixing the perfluorocarboxylic acid polyether with an organic base acid-binding agent which is 1.0-1.5 times of molar equivalent of the perfluorocarboxylic acid polyether and a transamidation reagent which is 1.0-1.5 times of molar equivalent at the temperature of-5-5 ℃ to obtain a solution A; dissolving a hydrophilic group modified by a terminal amino group in a solvent, and mixing the solution with an organic base acid-binding agent which is equivalent to 2.5-3.5 molar equivalents of the hydrophilic group at the temperature of-5-5 ℃ to obtain a solution B; mixing the solution A and the solution B according to the molar ratio of the perfluorocarboxylic acid polyether to the hydrophilic group modified by the terminal amino group of 1 (0.5-1.5), reacting at-5-5 ℃, and then heating the reaction system to 15-65 ℃ for continuous reaction to obtain the surfactant. The method is simple, rapid, environment-friendly and high in yield, and is favorable for rapid batch industrial production. The use of said surfactants is also disclosed.

Description

Preparation method and application of perfluoropolyether surfactant containing amide bonds

Technical Field

The invention belongs to the field of surfactants, and particularly relates to a method for preparing an amido bond-containing perfluoropolyether surfactant and application of the surfactant.

Background

The micro-droplets have micro-volume, independent chamber and rapid mass and heat transfer effect, so that the micro-droplets are widely applied to preparation of micro-reactors and complex multi-core-shell structures and biomedical application research, such as drug encapsulation, targeted drug delivery systems and single cell analysis. The liquid drop has the characteristics of good monodispersity and high controllability, so that the liquid drop provides an excellent place for accommodating micro-nano scale biochemical reaction. The stability of the liquid drop is the key to the application of the liquid drop microfluidic technology, and the stable liquid drop system has great application potential in the aspects of biochemical analysis and high-throughput screening of biological activity.

The fluorinated oil has the advantages of good air permeability, chemical and biological inertness, low viscosity, easy volatilization and the like, and is widely used for continuous corresponding liquid drop microfluidics. The use of fluorinated oils in droplet microreactors is limited due to their low solubility with conventional hydrocarbons. One effective method is to use a fluorinated surfactant. The fluorinated surfactant is prepared by replacing H atoms in a hydrophobic tail chain of a conventional surfactant with F atoms, and can greatly increase the solubility of the surfactant in fluorinated oil. In addition, the 'polar' head group of the surfactant can be a hydrophilic head group or a long-chain fatty head group of a lipophilic phase, so that the fluorinated surfactant is adsorbed on the interface between the fluorinated oil and the immiscible phase, and the fluorinated oil-water interface is stabilized. Thus, fluorinated surfactants are key factors for fluorinated oils as good carriers in droplet microfluidics.

The methods for synthesizing fluorosurfactants reported at present mainly include the acid chloride method and the "click" chemistry method, but these methods all have some disadvantages, such as high reaction temperature, complicated process, and low yield. In addition, because some reactions involve toxic reagents such as thionyl chloride, phosphorus trichloride and the like which cause corrosive environmental pollution, a large amount of fluorine solvent is needed for subsequent reactions, and the defects of high price and great environmental hazard exist. Therefore, a method for exploring the fluorinated surfactant with short synthesis time and simple reaction process according to different application scenes is needed.

Researchers in this field have attempted to improve fluorosurfactants and their preparation or synthesis at various angles, for example, CN 108285537 a provides a thermally stable and biocompatible amide bond-containing fluorosurfactant; CN 106823986 a provides a three-stage fluorinated surfactant, which is obtained by mixing and reacting fluoropolyether and polyethylene glycol diamine; CN 107754723 a provides a fluorocarbon surfactant for high-throughput digital microdroplet PCR, which has high purity, and good biocompatibility and stability, and is obtained by electrostatic interaction of cation part and anion part at water-oil two-phase interface.

Disclosure of Invention

The inventor of the application aims at the problems and provides a method for preparing an amido bond-containing perfluoropolyether surfactant, and the method has the characteristics of simple preparation, rapidness, environmental protection and high yield.

According to the present invention, there is provided a method for producing an amide bond-containing perfluoropolyether surfactant, the method comprising the steps of:

preparation of solution a: dissolving perfluorocarboxylic acid polyether shown in a formula (I) in a solvent, and mixing the perfluorocarboxylic acid polyether with an organic base acid-binding agent which is 1.0-1.5 times of molar equivalent of the perfluorocarboxylic acid polyether and a transamidation reagent which is 1.0-1.5 times of molar equivalent at the temperature of-5 ℃ to obtain a solution A containing an intermediate product shown in a formula (II);

wherein, m is 20-90, R is C1-C6 alkyl;

preparation of solution B: dissolving a hydrophilic group modified by a terminal amino group in a solvent, and mixing the hydrophilic group with an organic base acid-binding agent with the molar equivalent of 2.5-3.5 of the hydrophilic group at the temperature of-5 ℃, for example, for 10-60min to obtain a solution B;

solution a and solution B were mixed to carry out a reaction: mixing the solution A and the solution B according to the molar ratio of 1 (0.5-1.5) of the perfluorocarboxylic acid polyether to the hydrophilic group modified by the terminal amino group, and reacting at-5 ℃ for 30-90min for example; then heating the reaction system to 15-65 ℃ to continue the reaction for 0.5-24h, and obtaining the perfluoropolyether surfactant containing amide bonds as shown in the following formula (III-1) or (III-2).

According to an embodiment of the present invention, wherein solution a may be prepared by a method comprising the steps of:

a-1, putting perfluorocarboxylic acid polyether shown in a formula (I) into a container, adding a solvent to dissolve the perfluorocarboxylic acid polyether, and then placing the mixture at a temperature of-5 ℃;

a-2, at the temperature of-5 ℃, adding organic base which is 1.0-1.5 times of molar equivalent of perfluorocarboxylic acid polyether into the solution obtained in the step A-1 to serve as an acid-binding agent, and stirring;

a-3 continuously adding 1.0-1.5 times of molar equivalent of a transamidating agent to the mixture obtained in the step A-2, and continuously reacting at-5 ℃ to 5 ℃, for example, reacting for 20-60min to obtain a solution A containing the intermediate product shown in the formula (II).

According to an embodiment of the present invention, wherein solution B may be prepared by a method comprising the steps of:

b-1, dissolving the hydrophilic group modified by the terminal amino group in a solvent, and stirring at-5 ℃, for example, for 10-30 min;

b-2, adding organic base which is 2.5-3.5 molar equivalents of the hydrophilic group into the solution obtained in the step B-1 as an acid-binding agent, and stirring at-5 ℃, for example, for 10-30min to obtain a solution B.

According to the invention, the molecular weight of the amide bond-containing perfluoropolyether surfactant can be 2700-17000, and the structure of the amide bond-containing perfluoropolyether surfactant can be two-stage or three-stage.

According to the invention, in the preparation of solution A, the amount of solvent used may be between 5 and 20mL mmol relative to the perfluorocarboxylic acid polyether^-1。

According to the invention, in the preparation of solution a, the solvent may be a fluorine-containing solvent, preferably a perfluorinated solvent.

According to the invention, in the preparation of the solution A, the solvent is one or more mixed solvents selected from HFE-7100, HFE-7500, FC-40, FC-43 and FC-770.

According to the invention, in the preparation of the solution a, the acid scavenger may be one or more of tertiary amine organic bases.

According to the invention, in the preparation of the solution A, the acid-binding agent can be one or more selected from N-methylmorpholine, triethylamine and 4-dimethylaminopyridine.

According to the invention, in the preparation of the solution A, the acid-binding agent is used in an amount of 1.0 to 1.3 times equivalent to that of the perfluorocarboxylic acid polyether.

According to the present invention, in the preparation of the solution A, the standing time of the solution in the step A-1 may be 5 to 30 min.

According to the present invention, in the preparation of the solution A, the stirring time in the step A-2 may be 5 to 30 min.

According to the invention, in the preparation of solution A, the transamidating agent may be chosen from ethyl chloroformate, isobutyl chloroformate, 2-ethoxy-1-ethoxycarbonyl-1, 2-dihydroquinoline, which may preferably be added in an amount of 1.0 to 1.3 times the molar equivalent of the perfluoropolyether.

The addition of the transamidation reagent according to the invention allows for milder reaction conditions, water resistance, and lower reaction temperatures.

According to the invention, in the preparation of solution A, the reaction time may be continued for 0.5 to 1.5h after addition of the transamidating agent.

According to the invention, in the preparation of solution B, the hydrophilic group modified with a terminal amino group may be selected from Tris; monoaminated polyethylene glycols, e.g. NH₂-PEGx-OH，NH₂-PEGx-COOH，NH₂-PEGx-SH，NH₂-PEGx-N₃X represents a repeating unit and is 10 to 90; amino-terminated poly (N-isopropylacrylamide) (NH)₂PNIPAm), the molecular weight may be 2000-8000; amino-terminated poly (2-ethyl-2-oxazoline) (PEtOx), which may have a molecular weight of 200-10000; bis-aminated polyethylene glycol NH₂-PEGx-NH₂X represents a repeating unit and is 10 to 90; polyetheramine (ED), molecular weight can be 300-3000; and (3) amination of chitosan.

According to the invention, in the preparation of the solution B, the acid-binding agent can be one or more of tertiary amine organic bases.

According to the invention, in the preparation of the solution B, the acid-binding agent can be one or more tertiary amine organic bases selected from N-methylmorpholine, triethylamine and 4-dimethylaminopyridine.

According to the invention, in the preparation of the solution B, the stirring time after the acid-binding agent is added can be 10-30 min.

According to the present invention, in the mixing reaction of solution A and solution B, if the terminal amino group-modified hydrophilic group is a single terminal amino group-modified hydrophilic group, the amount thereof is 1.0 to 1.2 times equivalent to that of the perfluorocarboxylic acid polyether; if the hydrophilic group modified by the terminal amino group is a hydrophilic group modified by the double terminal amino groups, the equivalent is 0.5 to 0.52 times of that of the perfluorocarboxylic acid polyether.

According to the invention, after the mixed reaction of the solution A and the solution B, post-treatment can be carried out, wherein the post-treatment can be carried out by filtering unreacted substances or substances which are insoluble in the system, washing by using one or more of absolute ethyl alcohol, absolute methyl alcohol, water, tetrahydrofuran and dimethylformamide, and then removing the reaction solvent by reduced pressure evaporation, thus obtaining the perfluoropolyether surfactant containing amido bonds.

According to another aspect of the present invention there is provided a fluorinated oil comprising from 2% to 5% by weight of an amide bond-containing perfluoropolyether surfactant prepared according to the process described above.

According to the invention, the fluorinated oil can be a fluorinated oil known in the art, and comprises one or more mixed solvents of HFE-7500 fluorine oil, HFE-7100 fluorine oil, FC-40, FC-43 and FC-770.

According to another aspect of the present invention, there is provided a use of the amide bond-containing perfluoropolyether surfactant prepared according to the method described above in single cell encapsulation, high throughput digital PCR, in vitro diagnostics (IVC), and droplet sensors.

Compared with the prior art, the invention has the following advantages and positive effects:

(1) the method has the characteristics of no temperature dependence, short time consumption, high yield and the like.

(2) In the method, substances with strong corrosivity such as thionyl chloride, phosphorus oxychloride and the like are not used, so that the method is more environment-friendly.

(3) The acid anhydride used in the method is used as an intermediate state for transamidation, and no additional protection is needed to be carried out on hydrophilic groups containing hydroxyl groups, so that the method is simpler.

(4) The hydrophilic groups in the method of the invention are selected from various types, and are not limited to polyetheramine and aminopolyethylene glycol, but other hydrophilic substances containing amino groups, such as amino-terminated poly (N-isopropylacrylamide), chitosan, Tris (hydroxymethyl) aminomethane (Tris), amino-terminated poly (2-ethyl-2-oxazoline) (PEtOx) and the like, can be used.

(5) In the method, special anhydrous treatment and inert gas protection are not needed in the whole process, and the method is favorable for rapid batch industrial production.

Drawings

FIG. 1 is a schematic representation of a reaction process according to some embodiments of the present invention.

FIG. 2 is a graph showing the infrared absorption spectra of the starting material (formula (I)), the intermediate product (formula (II)), and the reaction product (formula (V)) in the reaction process for producing the amide bond-containing perfluoropolyether surfactant in example 1 according to the present invention.

FIG. 3 is an infrared absorption spectrum characterization of the products prepared according to example 2 of the present invention at different reaction times.

FIG. 4 is an infrared absorption light characterization of perfluoropolyether surfactants containing amide linkages prepared at room temperature in accordance with example 3 of the present invention.

FIG. 5 is a schematic diagram of the generation of uniform water-in-oil droplets by the microfluidic chip in example 5 according to the present invention.

Fig. 6 is a statistical and microscopic view of the droplet size of the surfactant provided in example 6 of the present invention at various stages.

FIG. 7 is an infrared absorption spectrum characterization of an amide bond-containing perfluoropolyether surfactant (formula (VII)) prepared in example 7 according to the present invention.

Detailed Description

Hereinafter, the present invention will be described in detail. Before the description is made, it should be understood that the terms used in the present specification and the appended claims should not be construed as limited to general and dictionary meanings, but interpreted based on the meanings and concepts corresponding to technical aspects of the present invention on the basis of the principle that the inventor is allowed to define terms appropriately for the best explanation. Accordingly, the description proposed herein is just a preferable example for the purpose of illustrations only, not intended to limit the scope of the invention, so it should be understood that other equivalents and modifications could be made thereto without departing from the spirit and scope of the invention.

The starting materials, equipment, and methods employed in the present application are those conventional in the art, unless otherwise specified.

Example 1

Preparation of solution a: 1mmol of the starting perfluorocarboxylic acid polyether (available from Krytox, model 157FSH, average molecular weight 7500, m-20-90) was first weighed 7.5g into a single neck flask as shown in formula (I):

dissolving the mixture by using 10mL solvent HFE 7100 through magnetic stirring, then placing the mixture at the temperature of 0 ℃ for 20min, then adding 1.2mmol of N-methylmorpholine, continuing to stir the mixture for 10min at the temperature of 0 ℃, and then slowly dropwise adding 1.2mmol of ethyl chloroformate, and continuing to react for 30min at the temperature of 0 ℃.

Preparation of solution B: in a separate one-neck flask, 0.51mmol of polyetheramine (ED) was weighed₉₀₀Purchased from Sigma, having an average molecular weight of 900, wherein x + y is from 6 to 125 and z is from 12 to 70, and having the structure shown in formula (IV):

adding 5mL of trifluoromethyl benzene, stirring at the low temperature of 0 ℃ for 20min, adding 1.5mmol of triethylamine, and stirring at the temperature of 0 ℃ for 10 min;

and pouring the solution A into the solution B, continuously stirring at the low temperature of 0 ℃ for 30min, recovering to the normal temperature, slowly heating to 60 ℃, and continuously reacting for 24 h.

(2) Purification of

After the reaction is finished, filtering the reaction solution, and removing insoluble substances to obtain a product solution; then adding a large amount of absolute ethyl alcohol, standing to remove the upper layer solution, washing with absolute ethyl alcohol for multiple times, taking the lower layer viscous substance, and drying in vacuum to obtain the product perfluoropolyether surfactant containing amide bonds, wherein the weight of the perfluoropolyether surfactant is 7.35g (the yield is 92.6%), wherein m is 20-90, x + y is 6-125, z is 12-70, and the structure is shown as the following formula (V):

(3) authentication

The result of infrared spectrum detection and verification of the amide bond-containing perfluoropolyether surfactant is shown in fig. 2.

As can be seen from the IR spectrum of FIG. 2, the IR spectrum of the starting material PFPE-COOH (formula (I)) showed a carbonyl peak at 1770cm^-1(stretching vibration of carbonyl peak in carboxylic acid) to form an intermediate state (formula (II)) during the reaction to give a product of terminal acid anhydride activated carboxyl group, the carbonyl peak of which shifted to 1780cm^-1(stretching vibration of carbonyl peak in acid anhydride), and the carbonyl peak of the final product perfluoro polyether surfactant containing amido bond (formula (V)) is shifted to 1680cm^-1(stretching vibration of carbonyl peak in amide bond). According to the infrared spectrogram, all the carboxyl groups in all the raw materials are converted into amide products, the theoretical yield is 100%, but the actual yield cannot reach 100% because the loss is inevitable in the purification process.

And verifying that the obtained product is the obtained perfluoropolyether surfactant containing amide bonds.

Example 2

The method is verified to be a fast and efficient preparation process.

As described in the reaction process of example 1, the solution a is poured into the solution B, the mixture is continuously stirred at a low temperature of 0 ℃ for 30min, after the normal temperature is recovered, the mixture is slowly heated to 60 ℃, and then partial products are taken out at 0.5h, 1.0h, 3.0h and 24.0h respectively, after the post-treatment, the infrared spectrum detection is carried out, and the result is shown in fig. 3, as can be seen from the infrared spectrum in fig. 3, the reaction is completely reacted at 0.5 h. The method is shown to be a fast and efficient preparation process.

Example 3

The method is verified to have no dependence on the reaction temperature.

The solution A was poured into the solution B as described in the reaction procedure of example 1, and the mixture was further stirred at 0 ℃ for 30min, and after returning to normal temperature, the mixture was reacted at room temperature for 24h, and after post-treatment, the amide bond-containing perfluoropolyether surfactant weighed 7.29g (yield: 91.84). The infrared spectrum detection is carried out, and the result is shown in figure 4, and the infrared spectrum shows that the reaction still has high efficiency at room temperature.

Example 4

Preparing a droplet forming oil: the perfluoropolyether surfactant containing an amide bond prepared in example 1 was dissolved in HFE-7500 (obtained from 3M company, model number HFE-7500) in an amount of 3% by mass.

Example 5

Verifying the droplet generation oil droplet generation experiments were performed.

Droplets were generated using the PDMS chip using the droplet generation oil prepared in example 4. The PDMS chip is manufactured independently, specifically, the polydimethylsiloxane prepolymer and the curing agent are mixed according to the proportion of 10: 1 (both prepolymer and curing agent were obtained from Dow Corning Corporation, midland, michigan, usa), the mixture was poured into the male mold of the flow focusing chip, after curing, the film was removed and bonded to glass, and the flow focusing chip was obtained with a cut size of 15 × 75 μm (width × length); the inner phase was made up of 20 wt% glycerol in 10mM PBS (pH 7.4) and the outer phase was made up of 3 wt% surfactant in HFE-7500 fluoro oil (example 4) at an inner to outer flow rate ratio of 1: 1.5 generating droplets.

Figure 5 shows a schematic of PDMS chips generating uniform water-in-oil droplets.

Example 6

The stability of the droplets generated in example 5 was verified.

The test verifies the thermal stability of the droplets obtained by microfluidics by programming the temperature to a certain temperature.

The temperature programming process is a standard method (ddPCR nucleic acid amplification method) which is currently used as a temperature-variable nucleic acid amplification process, and can be directly raising the temperature from room temperature to 95 ℃, or raising the temperature from room temperature to 65 ℃, maintaining the temperature at 65 ℃ for 30s, then raising the temperature from 65 ℃ to 95 ℃, and maintaining the temperature at 95 ℃ for 60s, wherein the whole process is repeated for 34 times. The thermal stability was judged by observing the droplets collected immediately, the droplets left at 37 ℃ for 5 days, and the droplets after programmed temperature rise with a microscope and counting the size distribution. The relevant dimensional statistics and microscopy results are shown in figure 6. It can be known that the droplets after being placed for 5 days and subjected to the thermal cycle treatment are basically not different from the initial droplets, i.e., the surfactant provided by the invention has better thermal stability.

Example 7

This embodiment is substantially the same as embodiment 1 except that: in the embodiment, the molecules serving as hydrophilic groups are bis-aminated polyethylene glycol (the average relative molecular mass is 600), the structure is shown as a formula (VI), and the structure of the obtained perfluoropolyether surfactant containing amide bonds is shown as a formula (VII); the infrared spectrum characterization is shown in FIG. 7; the carboxyl carbonyl peak of the raw material is completely from 1770cm^-1Move to the amido-carbonyl peak 1680cm^-1The conversion rate is high, and the yield is 95.0%.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is specific and detailed, but not to be understood as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. A method for preparing a perfluoropolyether surfactant containing amide bonds, the method comprising the steps of:

preparation of solution A: dissolving perfluorocarboxylic acid polyether shown in the following formula (I) in a solvent, and mixing the solution with an organic base acid-binding agent which is 1.0-1.5 times of molar equivalent of the perfluorocarboxylic acid polyether and a transamidation reagent which is 1.0-1.5 times of molar equivalent at-5 ℃ to obtain a solution A containing an intermediate product shown in the following formula (II);

wherein, m is 20-90, R is C1-C6 alkyl;

preparation of solution B: dissolving a terminal amino-modified hydrophilic group in a solvent, and mixing the solvent with an organic base acid-binding agent which is 2.5-3.5 molar equivalents of the hydrophilic group at-5 ℃ to obtain a solution B;

solution a and solution B were mixed to carry out a reaction: mixing the solution A and the solution B according to the molar ratio of 1 (0.5-1.5) between the perfluorocarboxylic acid polyether and the hydrophilic group modified by the terminal amino group, and reacting at-5 ℃; then heating the reaction system to 15-65 ℃ for continuous reaction to obtain the amide bond-containing perfluoropolyether surfactant shown in the following formula (III-1) or (III-2),

2. the method of claim 1, wherein solution a is prepared by a method comprising:

a-3, continuously adding a transamidation reagent which is 1.0-1.5 times of the molar equivalent of the perfluorocarboxylic acid polyether into the mixture obtained in the step A-2, and continuously reacting at-5 ℃ to obtain a solution A containing the intermediate product shown in the formula (II).

3. The method of claim 1, wherein solution B is prepared by a method comprising:

b-1, dissolving the hydrophilic group modified by the terminal amino group in a solvent, and stirring at the temperature of-5 ℃;

b-2, adding organic base which is equivalent to 2.5-3.5 molar equivalents of the hydrophilic group into the solution obtained in the step B-1 to be used as an acid-binding agent, and stirring at the temperature of-5 ℃ to obtain a solution B.

4. The method of any one of claims 1 to 3,

in the preparation of the solution A, the solvent is a fluorine-containing solvent, and preferably, the solvent is one or more mixed solvents selected from HFE-7100, HFE-7500, FC-40, FC-43 and FC-770; and/or

In the preparation of the solution A, the acid-binding agent is one or more of tertiary amine organic bases, preferably, the acid-binding agent is one or more of N-methylmorpholine, triethylamine and 4-dimethylaminopyridine; and/or

In the preparation of the solution A, the dosage of the acid-binding agent is 1.0-1.3 times of equivalent of the perfluorocarboxylic acid polyether; and/or

In the preparation of solution A, the transamidating agent is selected from the group consisting of ethyl chloroformate, isobutyl chloroformate, 2-ethoxy-1-ethoxycarbonyl-1, 2-dihydroquinoline, and is preferably added in an amount of 1.0 to 1.3 times molar equivalent to the perfluorocarboxylic acid polyether.

5. The method of any one of claims 1 to 3,

in the preparation of solution B, the terminal amino-modified hydrophilic group is selected from tris; monoaminated polyEthylene glycols, e.g. NH₂-PEGx-OH，NH₂-PEGx-COOH，NH₂-PEGx-SH，NH₂-PEGx-N₃X represents a repeating unit and is 10 to 90; amino-terminated poly (N-isopropylacrylamide), molecular weight 2000-8000; amino-terminated poly (2-ethyl-2-oxazoline) having a molecular weight of 200-10000; bis-aminated polyethylene glycol NH₂-PEGx-NH₂X represents a repeating unit and is 10 to 90; polyetheramine with molecular weight of 300-3000; amination of chitosan; and/or

In the preparation of the solution B, the acid-binding agent is one or more of tertiary amine organic bases, for example, the acid-binding agent is one or more of tertiary amine organic bases selected from N-methylmorpholine, triethylamine and 4-dimethylaminopyridine.

6. The method as claimed in any one of claims 1 to 3, wherein the amide bond-containing perfluoropolyether surfactant has a molecular weight of 2700-.

7. The method according to claim 1, wherein, in the mixing reaction of the solution A and the solution B, if the terminal amino-modified hydrophilic group is a single terminal amino-modified hydrophilic group, the amount thereof is 1.0 to 1.2 times equivalent to that of the perfluorocarboxylic acid polyether; if the hydrophilic group modified by the terminal amino group is a hydrophilic group modified by the double terminal amino groups, the equivalent is 0.5 to 0.52 times of that of the perfluorocarboxylic acid polyether.

8. The method according to any one of claims 1 to 3, wherein after the mixed reaction of the solution A and the solution B, a post-treatment is performed, the post-treatment comprising filtering an unreacted substance or a substance insoluble in the system, washing with one or more selected from the group consisting of anhydrous ethanol, anhydrous methanol, water, tetrahydrofuran, and dimethylformamide, and thereafter removing the reaction solvent by evaporation under reduced pressure.

9. A fluorinated oil comprising 2-5 wt% of an amide bond-containing perfluoropolyether surfactant prepared according to the process of any one of claims 1 to 8.

10. Use of the perfluoropolyether surfactants containing amide linkages prepared according to the method of any one of claims 1 to 8 in single cell encapsulation, high throughput digital PCR, in vitro diagnostics (IVC), and droplet sensors.