Preparation method and application of polyether composite surfactant

Abstract

The application relates to a preparation method and application of a polyether composite surfactant, and belongs to the technical field of surfactants. The fluorocarbon hydrophobic block and the polyether hydrophilic chain segment in the molecular structure of the perfluoropolyether surfactant can significantly reduce the surface tension of a system, endow the polyether composite surfactant with high efficient wetting and spreading capacity, and the potassium salt of a phosphate ester is prepared by taking bisphenol A polyoxyethylene ether as raw material, and by performing esterification, directional hydrolysis and salting reaction, the polyether chain segment and the potassium salt of a phosphate ester group are contained in the molecule, the interfacial affinity and the adhesion stability can be greatly improved, the low-temperature molecular compounding process is adopted to form a molecular-level uniform dispersion system, the fluorosilicon chain segment dominates the reduction of the surface tension and the realization of rapid spreading, the potassium salt of a phosphate ester strengthens the interfacial affinity and the adhesion stability, and the two can solve the problems of insufficient interfacial adhesion of a single fluorosilicon surfactant and limited wetting capacity of a single phosphate ester surfactant.

Description

Technical Field

[0001] This invention belongs to the field of surfactant technology, and relates to a method for preparing a polyether-based composite surfactant and its application. Background Technology

[0002] Polyether nonionic surfactants, with their adjustable HLB values, low foaming properties, resistance to acids, alkalis, and salts, and excellent compatibility, are key additives for industrial interface control and are widely used in daily chemicals, textiles, pesticides, polyurethanes, oil fields, industrial cleaning, and water-based coatings. Traditional single polyethers are mostly synthesized by block polymerization of ethylene oxide and propylene oxide with fatty alcohols and polyols as initiators under alkaline or bimetallic cyanide catalysis. While they possess basic emulsifying and dispersing properties, they generally suffer from insufficient wetting properties, poor stability, difficulty in simultaneously achieving defoaming and foam stabilization, and decreased interfacial activity under complex conditions such as high temperature, high salt, and strong shear, failing to meet the demands of high-end applications.

[0003] Chinese invention patent application CN114106854A discloses a modified organosilicon surfactant and its application. The preparation method includes: Step 1: Propylene alcohol and an epoxide react at 70-90℃ for 5-10 hours under a catalyst and a reaction pressure ≤0.3 MPa to obtain propynyl alcohol polyether; Step 2: The propynyl alcohol polyether reacts with an alkali at 30-60℃ for 1-4 hours, then an alkyl end-capping agent is added, and the reaction is carried out at 30-80℃ for 4-10 hours to obtain propynyl alcohol-terminated polyether; Step 3: The propynyl alcohol-terminated polyether undergoes a hydrosilylation reaction with a hydrosilicone oil under the catalysis of chloroplatinic acid to obtain the modified organosilicon surfactant. The prepared pesticide emulsion solves the problem of excessive foaming in existing technologies and also exhibits hydrolysis resistance over a wide pH range.

[0004] The above technical solutions do not address how to reduce the surface tension of the pesticide solution to the ultra-low range required by the leaves of waxy crops, nor do they overcome the core problems of stable binding between surfactants and leaf epidermis and easy roll-off and loss of pesticide solution. Traditional polyether surfactants are mostly prepared by block polymerization of ethylene oxide / propylene oxide using fatty alcohols, alkylphenols or ordinary bisphenol A as initiators. The molecules contain only conventional polyether hydrophilic chains and aliphatic / aromatic hydrophobic chains. The surface energy of the hydrophobic chain segments is relatively high, which makes it impossible to reduce the surface tension of pesticide suspension solutions to the ultra-low range required by the leaves of waxy crops. It is also impossible to form stable intermolecular forces with the leaf epidermis, making the pesticide solution easy to roll off and lose, ultimately resulting in poor wetting and spreading performance. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing polyether-based composite surfactants and their applications. By combining perfluoropolyether siloxane block amidation and bisphenol A polyoxyethylene ether phosphorylation, a composite surfactant is obtained, which solves the problems of poor wetting, low suspension rate, and insufficient hard water resistance and thermal storage stability of traditional products.

[0006] The objective of this invention can be achieved through the following technical solutions: A method for preparing a polyether-based composite surfactant includes the following steps: Step 1: Under the catalysis of triethylamine, perfluoropolyether-siloxane block carboxylic acid and alkyl chloroformate undergo a mixed anhydride activation reaction to obtain a mixed anhydride intermediate solution. Then, through an amidation coupling reaction, the amino groups in the diamino polyethylene glycol and the anhydride groups in the mixed anhydride intermediate solution are grafted together to obtain a perfluoropolyether surfactant.

[0007] Step 2: Bisphenol A polyoxyethylene ether and pyrophosphate are grafted together through esterification, followed by hydrolysis and neutralization to obtain potassium phosphate salt.

[0008] Step 3: Combine potassium phosphate salt, deionized water, perfluoropolyether surfactant and silicone defoamer to obtain polyether composite surfactant.

[0009] Furthermore, the specific preparation process of the mixed anhydride intermediate solution is as follows: Perfluoropolyether-siloxane block carboxylic acid and environmentally friendly hydrofluoroether HFE-7500 are added to a reactor and stirred for 10-15 min at 0-2℃ and 300-500 r / min under a nitrogen atmosphere. Triethylamine and alkyl chloroformate are added sequentially, and stirring is continued for 30-40 min to obtain a mixed anhydride intermediate solution.

[0010] Triethylamine, as an organic base, can both catalyze the activation of carboxylic acids and neutralize the byproduct hydrogen chloride, thus shifting the reaction equilibrium to the forward direction. By adding triethylamine first and then alkyl chloroformate, the side reactions caused by local excess of alkyl chloroformate can be avoided, ensuring that the carboxylic acid group is precisely activated. Stirring ensures that the carboxylic acid and alkyl chloroformate react completely, generating a high-purity and highly stable mixed anhydride intermediate solution in situ, providing a reliable active intermediate for subsequent amidation coupling reactions.

[0011] Furthermore, the ratio of perfluoropolyether-siloxane block carboxylic acid, environmentally friendly hydrofluoroether HFE-7500, triethylamine and alkyl chloroformate is 100-150g: 80-100mL: 1.54-1.82mL: 2.6-3.1mL.

[0012] The formulation has been optimized through reaction thermodynamics and kinetics. The solvent ratio ensures that the system viscosity is moderate and the stirring is uniform. The amount of catalyst and activator are precisely matched to the stoichiometric ratio of carboxylic acid activation. This can achieve complete activation of carboxylic acid while avoiding excessive reagent residue, thus ensuring the efficiency of intermediate formation and the purity of the product.

[0013] Furthermore, the alkyl chloroformate is any one of ethyl chloroformate, butyl chloroformate, and propyl chloroformate.

[0014] All three are short-chain alkyl chloroformates. The short-chain alkyl groups have low steric hindrance, which does not affect the rate of nucleophilic substitution reaction. They are fully compatible with existing processes. The resulting mixed anhydride intermediates have similar structures and stability. The subsequent amidation coupling reaction with diamino polyethylene glycol is no different, which can ensure the regularity of the molecular structure of the perfluoropolyether surfactant and the consistency of product performance.

[0015] Furthermore, the specific preparation process of the perfluoropolyether surfactant is as follows: Diamino polyethylene glycol, trifluorotoluene, and triethylamine were added to a reaction vessel and stirred for 10-12 min at 0-2℃ and 300-500 r / min under a nitrogen atmosphere. Then, a mixed anhydride intermediate solution was slowly added dropwise to the reaction vessel. After the addition was complete, the mixture was kept warm and stirred for 5-10 min. The reaction was continued for 30-40 min at 20-25℃ and 300-500 r / min. After the reaction was completed, anhydrous ethanol was added to terminate the reaction. The mixture was washed, purified, and dried to obtain a perfluoropolyether surfactant.

[0016] The amidation process employs low-temperature drop-addition followed by room-temperature aging. Triethylamine acts as an acid-binding agent to neutralize the accessory acid in a timely manner, promoting the directional reaction. Low-temperature control can avoid cross-linking side reactions caused by local overheating. Purification can efficiently remove solvents and unreacted raw materials. The resulting product has a regular molecular structure, excellent amphiphilicity, and no impurity residues.

[0017] Furthermore, the ratio of the amount of diamino polyethylene glycol, trifluorotoluene, triethylamine and mixed anhydride intermediate solution is 6.0-10.0 g : 50-70 mL : 3-5 mL : 103-143 mL.

[0018] This ratio ensures that the amino and anhydride groups react completely in stoichiometric proportions, the amount of solvent is adapted to the dispersion requirements of the system, and the acid-binding agent can completely neutralize the byproducts, which not only improves the reaction yield but also avoids the influence of excessive reagents on product purity and subsequent compounding stability.

[0019] Furthermore, the specific preparation process of potassium phosphate salt is as follows: Bisphenol A polyoxyethylene ether was added to a reactor, and pyrophosphate was added at 40-50℃ and 300-500 r / min. The temperature was raised to 60-65℃ and the reaction was carried out for 2-3 hours. Deionized water was added and the reaction was carried out at 60-70℃ for 2-3 hours. The mixture was then neutralized with potassium hydroxide aqueous solution and the pH was adjusted to 8-9 to obtain potassium phosphate salt.

[0020] Based on the principle of selective esterification-directional hydrolysis, pyrophosphate reacts precisely with hydroxyl groups. The hydrolysis step converts polyphosphate esters into high-purity phosphate monoesters, significantly improving water solubility and hard water resistance, while enhancing molecular thermal stability. The neutralized product is highly hydrophilic, electrolyte resistant, and has excellent compatibility.

[0021] Furthermore, the mass ratio of bisphenol A polyoxyethylene ether, pyrophosphate, and deionized water is 100-150: 11.2-15.4: 2.2-3.2.

[0022] This mass ratio is the optimal ratio for esterification-hydrolysis, which can ensure complete esterification of hydroxyl groups and thorough hydrolysis reaction, effectively improve the content and esterification rate of phosphate monoesters, avoid raw material residues or by-products, and ensure the surface activity and application stability of potassium phosphate salts.

[0023] Furthermore, the ratio of potassium phosphate salt, deionized water, perfluoropolyether surfactant, and silicone defoamer is 50-60g: 50-60mL: 10-20g: 0.2-0.4g.

[0024] The compound formulation has been optimized through functional synergy. Potassium phosphate salt serves as the hydrophilic and hard water resistant core, perfluoropolyether surfactant serves as the wetting and enhancing core, and organosilicon defoamer controls the foam of the system. The matching ratio of each component can achieve uniform dispersion at the molecular level, without stratification or flocculation, and fully exert the synergistic effect.

[0025] Application of a polyether-based composite surfactant in pesticide synergistic adjuvants.

[0026] The beneficial effects of this invention are: 1. The perfluoropolyether surfactant of the present invention contains fluorocarbon hydrophobic blocks and polyether hydrophilic segments in its molecular structure, which can significantly reduce the surface tension of the system and endow polyether composite surfactants with efficient wetting and spreading ability. The potassium phosphate salt is prepared by esterification, directional hydrolysis and salt formation reaction of bisphenol A polyoxyethylene ether as raw material. The molecule contains polyether segments and potassium phosphate salt groups, which can greatly improve interfacial affinity and adhesion stability. The two are used to form a molecularly uniform dispersion system under low temperature molecular compounding process. The fluorosilicone segments mainly reduce the surface tension and achieve rapid spreading, while the potassium phosphate salt strengthens the interfacial affinity and adhesion stability. The two work together to solve the problems of insufficient interfacial adhesion of single fluorosilicone surfactants and limited wetting ability of single phosphate surfactants, and greatly improve the wetting, spreading and stable adhesion ability of polyether composite surfactants on leaf surfaces.

[0027] 2. The perfluoropolyether surfactant of this invention introduces a hydrophilic structure through the diamino polyethylene glycol segment, improving the poor water solubility of traditional fluorosilicone surfactants. After neutralization, the potassium phosphate salt exhibits outstanding water solubility and emulsifying ability. Furthermore, the stepwise process of first dissolving the potassium phosphate salt in water and then compounding it with the perfluoropolyether surfactant allows for complementary hydrogen bonds between the polyether segments. The spatial structures of the fluorosilicone chain and the polyether chain are compatible, synergistically solving the problems of difficult dispersion of single fluorosilicone components in aqueous phase and insufficient emulsification of non-polar components by single phosphate components. This results in uniform dispersion of the composite system in the aqueous phase, strong emulsification stability, and no stratification or flocculation.

[0028] 3. The fluorosilicone block of the perfluoropolyether surfactant of the present invention has strong chemical inertness, excellent acid and alkali resistance and weather resistance, and the phosphate group of potassium phosphate can resist electrolyte interference. In the compound system, the fluorosilicone block provides chemical protection in extreme environments, and the potassium phosphate chelates hard water ions and maintains the stability of the system. Combined with the low temperature and mild preparation process throughout, the stable structure of each component is preserved to the greatest extent. The two work together to greatly improve the product's resistance to hard water, acid and alkali and aging resistance, and extend the shelf life of storage and application. Detailed Implementation

[0029] To further illustrate the technical means and effects of the present invention in achieving the intended purpose, the following detailed description of the specific implementation methods, features and effects of the present invention, in conjunction with preferred embodiments, is provided below.

[0030] Example 1: This example provides a method for preparing a polyether-based composite surfactant, comprising the following steps: S1: Add 100g of perfluoropolyether-siloxane block carboxylic acid and 80mL of environmentally friendly hydrofluoroether HFE-7500 to the reactor. Stir for 10min at 0℃ and 300r / min under a nitrogen atmosphere. Then add 1.54mL of triethylamine and 2.6mL of ethyl chloroformate in sequence. Continue stirring for 30min at 0℃ and 300r / min to obtain a mixed anhydride intermediate solution.

[0031] Under low-temperature stirring conditions, triethylamine acts as an organic base catalyst, and perfluoropolyether-siloxane block carboxylic acid and ethyl chloroformate undergo a mixed anhydride activation reaction, converting the carboxylic acid end in situ into highly reactive mixed anhydride groups, ultimately yielding a stable mixed anhydride intermediate solution.

[0032] S2: 6.0 g of diamino polyethylene glycol (NH2-PEG600-NH2), 50 mL of trifluorotoluene and 3 mL of triethylamine were added to the reactor. The mixture was stirred for 10 min at 0 °C and 300 r / min under a nitrogen atmosphere. Then, 103 mL of mixed acid anhydride intermediate solution was slowly added dropwise to the reactor. After the addition was complete, the mixture was kept at 0 °C and stirred for 5 min. The ice bath was removed, and the reaction was continued for 30 min at 20 °C and 300 r / min. After the reaction was completed, anhydrous ethanol was added to terminate the reaction. The product was washed three times with anhydrous ethanol, and the upper waste liquid was removed by gravity sedimentation. The operation was repeated three times. The product was then vacuum dried at 60 °C for 24 h to obtain the perfluoropolyether surfactant.

[0033] Under low-temperature stirring conditions, trifluorotoluene was used as the reaction solvent and triethylamine as the acid-binding agent. The diamino polyethylene glycol was thoroughly mixed, and then a mixed acid anhydride intermediate solution was slowly added dropwise. After being kept at low temperature, the mixture was raised to room temperature to continue the reaction. This allowed the highly active mixed acid anhydride groups to undergo an amidation coupling reaction with the terminal primary amino groups of the molecules. The hydrophobic chain of the perfluoropolyether was covalently bonded to the hydrophilic chain of the polyether to form the target product. After the reaction was completed, the reaction was terminated with anhydrous ethanol, purified by repeated washing and reprecipitation, and vacuum dried to obtain a high-purity perfluoropolyether surfactant.

[0034] S3: Add 100g of bisphenol A polyoxyethylene ether to the reactor, add 11.2g of pyrophosphate at 40℃ and 300r / min, raise the temperature to 60℃ and react for 2h, add 2.2g of deionized water at once, and hydrolyze at 60℃ for 2h. After the hydrolysis reaction is completed, neutralize with a 30wt% potassium hydroxide aqueous solution and adjust the pH of the product to 8 to obtain potassium phosphate salt.

[0035] The terminal hydroxyl groups in the bisphenol A polyoxyethylene ether molecule undergo nucleophilic substitution esterification with pyrophosphate to generate a mixed intermediate of phosphate monoester, phosphate diester, pyrophosphate ester, and polyphosphate ester. Subsequently, deionized water is added to carry out a hydrolysis reaction, which directionally converts the unstable polyphosphate ester and pyrophosphate ester into high-purity phosphate monoester. Finally, the solution is neutralized to pH 8 with potassium hydroxide aqueous solution to complete the salt formation reaction, and finally, a potassium phosphate salt with excellent water solubility is obtained.

[0036] S4: Add 50g of potassium phosphate salt and 50mL of deionized water to the reactor, stir for 15min at 40℃ and 300r / min, then slowly add 10g of perfluoropolyether surfactant, keep warm and stir for 30min to perform molecular compounding. After the heat preservation is completed, cool down to 25℃, add 0.2g of organosilicon defoamer, stir for 10min to obtain polyether composite surfactant.

[0037] Example 2: This example provides a method for preparing a polyether-based composite surfactant, comprising the following steps: S1: Add 125g of perfluoropolyether-siloxane block carboxylic acid and 90mL of environmentally friendly hydrofluoroether HFE-7500 to the reactor. Stir for 12min at 1℃ and 400r / min under a nitrogen atmosphere. Then add 1.68mL of triethylamine and 2.8mL of ethyl chloroformate in sequence. Continue stirring for 35min at 1℃ and 400r / min to obtain a mixed anhydride intermediate solution.

[0038] S2: Add 8.0 g of diamino polyethylene glycol (NH2-PEG600-NH2), 60 mL of trifluorotoluene, and 4 mL of triethylamine to a reactor. Stir for 11 min at 1 °C and 400 r / min under a nitrogen atmosphere. Then, slowly add 123 mL of mixed acid anhydride intermediate solution dropwise to the reactor. After the addition is complete, keep the reactor at 1 °C and stir for 7 min. Remove the ice bath and continue the reaction at 22 °C and 400 r / min for 35 min. After the reaction is complete, add anhydrous ethanol to terminate the reaction. Wash the product with anhydrous ethanol 4 times. Remove the upper waste liquid by gravity sedimentation. Repeat the operation 4 times. Place the product in a vacuum dryer at 70 °C for 25 h to obtain a perfluoropolyether surfactant.

[0039] S3: Add 125g of bisphenol A polyoxyethylene ether to the reactor, add 13.3g of pyrophosphate at 45℃ and 400r / min, raise the temperature to 62℃ and react for 2h, add 2.7g of deionized water at once, and hydrolyze at 65℃ for 2h. After the hydrolysis reaction is completed, neutralize with a 30wt% potassium hydroxide aqueous solution and adjust the pH of the product to 8.5 to obtain potassium phosphate salt.

[0040] S4: Add 55g of potassium phosphate salt and 55mL of deionized water to the reactor, stir for 17min at 45℃ and 400r / min, then slowly add 15g of perfluoropolyether surfactant, keep warm and stir for 35min to perform molecular compounding. After the heat preservation is completed, cool down to 27℃, add 0.3g of organosilicon defoamer, stir for 12min to obtain polyether composite surfactant.

[0041] Example 3: This example provides a method for preparing a polyether-based composite surfactant, comprising the following steps: S1: Add 150g of perfluoropolyether-siloxane block carboxylic acid and 100mL of environmentally friendly hydrofluoroether HFE-7500 to the reactor. Stir for 15min at 2℃ and 500r / min under a nitrogen atmosphere. Then add 1.82mL of triethylamine and 3.1mL of ethyl chloroformate in sequence. Continue stirring for 40min at 2℃ and 500r / min to obtain a mixed anhydride intermediate solution.

[0042] S2: 10.0 g of diamino polyethylene glycol (NH2-PEG600-NH2), 70 mL of trifluorotoluene and 5 mL of triethylamine were added to the reactor. The mixture was stirred for 12 min at 2 °C and 500 r / min under a nitrogen atmosphere. Then, 143 mL of mixed anhydride intermediate solution was slowly added dropwise to the reactor. After the addition was complete, the mixture was kept at 2 °C and stirred for 10 min. The ice bath was removed, and the reaction was continued at 25 °C and 500 r / min for 40 min. After the reaction was completed, anhydrous ethanol was added to terminate the reaction. The product was washed 5 times with anhydrous ethanol, and the upper waste liquid was removed by gravity sedimentation. The operation was repeated 5 times. The product was placed at 80 °C and vacuum dried for 26 h to obtain the perfluoropolyether surfactant.

[0043] S3: Add 150g of bisphenol A polyoxyethylene ether to the reactor, add 15.4g of pyrophosphate at 50℃ and 500r / min, raise the temperature to 65℃ and react for 3h, add 3.2g of deionized water at once, and hydrolyze at 70℃ for 3h. After the hydrolysis reaction is completed, neutralize with a 30wt% potassium hydroxide aqueous solution and adjust the pH of the product to 9 to obtain potassium phosphate salt.

[0044] S4: Add 60g of potassium phosphate salt and 60mL of deionized water to the reactor, stir for 20min at 50℃ and 500r / min, then slowly add 20g of perfluoropolyether surfactant, keep warm and stir for 40min to perform molecular compounding. After the heat preservation is completed, cool down to 30℃, add 0.4g of organosilicon defoamer, stir for 15min to obtain polyether composite surfactant.

[0045] Example 4: This example provides a method for preparing a polyether-based composite surfactant. The difference from Example 1 is that butyl chloroformate is used instead of ethyl chloroformate in step S1.

[0046] Example 5: This example provides a method for preparing a polyether-based composite surfactant. The difference from Example 1 is that propyl chloroformate is used instead of ethyl chloroformate in step S1.

[0047] In the above examples, ethyl chloroformate, butyl chloroformate, and propyl chloroformate are all alkyl chloroformate esters.

[0048] Comparative Example 1: This comparative example provides a method for preparing a polyether-based composite surfactant. The difference from Example 1 is that potassium phosphate salt is removed in step S4.

[0049] Comparative Example 2: This comparative example provides a method for preparing a polyether-based composite surfactant. The difference from Example 1 is that the perfluoropolyether surfactant is removed in step S4.

[0050] Comparative Example 3: This comparative example provides a method for preparing a polyether-based composite surfactant. The difference from Example 1 is that perfluoropolyether carboxylic acid is used instead of perfluoropolyether-siloxane block carboxylic acid in step S1.

[0051] The sources of raw materials involved in the examples and comparative examples are shown below: Perfluoropolyether-siloxane block carboxylic acid: custom-made, molecular weight 4000-5000 g / mol, purchased from Hunan Weisbangya Trading Co., Ltd.; Environmentally friendly hydrofluoroether HFE-7500: purity 99.99%, purchased from Shanghai Junzi Adhesive New Material Technology Co., Ltd.; Triethylamine: purity ≥99%, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; Ethyl chloroformate: purity 99%, purchased from Huangshan Bashui Chemical Additives Co., Ltd.; Butyl chloroformate: purity ≥98%, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; Propyl chloroformate: purity ≥99%, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; Diamine Polyethylene glycol (PEG): molecular weight 600, purchased from Hubei Jiahuixingcheng Biotechnology Co., Ltd.; Trifluorotoluene: purity ≥99%, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; Triethylamine: purity ≥99%, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; Bisphenol A polyoxyethylene ether: purity ≥99%, purchased from Shandong Yousuo Chemical Technology Co., Ltd.; Pyrophosphate: purity ≥94%, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; Potassium hydroxide: purity ≥84%, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; Perfluoropolyether carboxylic acid: molecular weight 3000, purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0052] The performance of the polyether composite surfactants prepared in Examples 1-5 and Comparative Examples 1-3 was tested: Surface tension testing: Referring to GB / T 22237-2008 "Determination of surface tension of surfactants", a fully automatic static surface tension meter (JK99 M, Shanghai Zhongchen Digital Technology Equipment Co., Ltd.) was used with the platinum ring method (outer diameter 20.30 mm, platinum wire 0.30 mm, circumference 61.89 mm, density 0.998 g / cm³). 3 The test temperature was measured to be 25±2℃. First, aqueous solutions of surfactant with specific concentration gradients were prepared and left at room temperature overnight to allow for complete dissolution. The instrument was calibrated with high-purity water before each test. During the test, the pre-prepared solutions were poured into the measuring cell sequentially, and the static surface tension values ​​were recorded. Three tests were conducted, and the average value was taken.

[0053] 15.0 g of polyether composite surfactant, 0.28 g of preservative, 7 g of antifreeze, 90 mL of deionized water and 35 g of 95% etoxazole technical material prepared in Examples 1-5 and Comparative Examples 1-3 were added to a beaker in sequence and stirred evenly. After stirring evenly, the mixture was added to a sand mill, and finally 160 g of zirconium silicate beads (0.8 mm in diameter) were added. The mixture was ground at 1440 r / min for 2 h at room temperature. After filtering out the zirconium beads, a pesticide suspension was obtained.

[0054] Crop leaf contact angle: Refer to GB / T 30447-2013 "Method for Determination of Film Contact Angle" to test the contact angle of the pesticide solution on wheat leaves.

[0055] Pesticide suspension rate: Referring to GB / T 14825-2006 "Determination of Pesticide Suspension Rate", weigh 1.0000g of pesticide suspension sample and place it in a 250mL stoppered graduated cylinder. First, add 100mL of standard hard water to the stoppered graduated cylinder and shake well by hand to disperse the reagent evenly. Then, continue to add standard hard water and make up to 250mL. Stopper the cylinder and invert it 180° with the center of the cylinder as the axis. Return it to its original position as one cycle. Invert the cylinder 30 times within 1 minute. Open the stopper and place it in a constant temperature water bath at 25±0.1℃ for 30 minutes. Quickly remove 225mL of diluted SC from 5-10mm below the liquid surface using a vacuum pump, being careful not to disturb the precipitate at the bottom. Make up to 100mL.

[0056] Hard water resistance stability: Refer to GB / T 19136-2003 "Determination of hard water resistance of pesticide adjuvants" standard.

[0057] Thermal storage stability: In accordance with GB / T 19136-2003 "Determination of thermal storage stability of pesticides", the pesticides were stored at a constant temperature of 54℃ for 14 days, and the changes in appearance and performance were observed.

[0058] The test results are shown in the table below: Table 1 Performance Test Overview As shown in Table 1, the static surface tension and crop leaf contact angle of Examples 1-5 are all lower than those of Comparative Examples 1-3. This may be because Examples 1-5 use a synergistic compound of perfluoropolyether-siloxane block surfactant and potassium phosphate. The fluorosilicone block can significantly reduce the surface tension of the system, and the potassium phosphate can enhance interfacial affinity and spreading adhesion. The two work together to achieve excellent wetting and spreading effects. However, Comparative Example 1 lacks potassium phosphate, Comparative Example 2 lacks perfluoropolyether surfactant, and Comparative Example 3 does not introduce siloxane block, so it cannot form a functional synergy, resulting in higher surface tension and poor leaf wetting adhesion.

[0059] As shown in Table 1, the pesticide suspension rates of Examples 1-5 are greater than those of Comparative Examples 1-3. This may be because the polyether hydrophilic segments of the perfluoropolyether surfactant in Examples 1-5 work synergistically with the emulsifying and dispersing groups of potassium phosphate salt to form a stable dispersion film in the aqueous system, which can efficiently disperse pesticide particles and prevent agglomeration and sedimentation. In contrast, the comparative examples lack the core compound components, resulting in a significant decrease in emulsifying and dispersing ability, making the pesticide particles prone to sedimentation and leading to a lower suspension rate.

[0060] As shown in Table 1, the hard water resistance of Examples 1-5 is greater than that of Comparative Examples 1-2. This may be because the potassium phosphate salt in Examples 1-5 contains phosphate anionic groups, which can efficiently chelate calcium and magnesium ions in hard water, block the damage of the electrolyte to the surfactant system, and, combined with the chemical inertness of the fluorosilicone block, significantly improve the hard water resistance. Comparative Example 1 lacks potassium phosphate salt and Comparative Example 2 lacks perfluoropolyether surfactant, so they cannot form a synergistic protection against hard water, and the system is prone to stratification and precipitation.

[0061] As shown in Table 1, the thermal storage stability of Examples 1-5 is greater than that of Comparative Examples 1-3. This may be because Examples 1-5 adopt the amphiphilic structure of fluorosilicone block-siloxane, which can significantly improve the viscoelasticity and stability of the interfacial adsorption layer, making the compound system less prone to stratification and precipitation under thermal storage conditions, thereby improving thermal storage stability. Comparative Examples 1 and 2 lack key stabilizing components, and Comparative Example 3 did not introduce siloxane blocks, resulting in weaker viscoelasticity of the interfacial adsorption layer, making it prone to slight stratification during thermal storage.

[0062] It should be noted that, in this document, terms such as “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0063] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention.

Claims

1. A method for preparing a polyether-based composite surfactant, characterized in that, Includes the following steps: Step 1: Under the catalysis of triethylamine, perfluoropolyether-siloxane block carboxylic acid and alkyl chloroformate undergo a mixed anhydride activation reaction to obtain a mixed anhydride intermediate solution. Then, through an amidation coupling reaction, the amino groups in the diamino polyethylene glycol and the anhydride groups in the mixed anhydride intermediate solution are grafted together to obtain a perfluoropolyether surfactant. Step 2: Bisphenol A polyoxyethylene ether and pyrophosphate are grafted together through esterification, followed by hydrolysis and neutralization to obtain potassium phosphate salt. Step 3: Combine potassium phosphate salt, deionized water, perfluoropolyether surfactant and silicone defoamer to obtain polyether composite surfactant.

2. The method for preparing a polyether-based composite surfactant according to claim 1, characterized in that, The specific preparation process of the mixed anhydride intermediate solution in step one is as follows: Perfluoropolyether-siloxane block carboxylic acid and environmentally friendly hydrofluoroether HFE-7500 are added to a reactor and stirred for 10-15 min at 0-2℃ and 300-500 r / min under a nitrogen atmosphere. Triethylamine and alkyl chloroformate are added sequentially, and stirring is continued for 30-40 min to obtain a mixed anhydride intermediate solution.

3. The method for preparing a polyether-based composite surfactant according to claim 2, characterized in that, The ratio of the amount of the perfluoropolyether-siloxane block carboxylic acid, the environmentally friendly hydrofluoroether HFE-7500, the triethylamine and the alkyl chloroformate is 100-150g: 80-100mL: 1.54-1.82mL: 2.6-3.1mL.

4. The method for preparing a polyether-based composite surfactant according to claim 3, characterized in that, The alkyl chloroformate is any one of ethyl chloroformate, butyl chloroformate, and propyl chloroformate.

5. The method for preparing a polyether-based composite surfactant according to claim 1, characterized in that, The specific preparation process of the perfluoropolyether surfactant mentioned in step one is as follows: Diamino polyethylene glycol, trifluorotoluene, and triethylamine were added to a reaction vessel and stirred for 10-12 min at 0-2℃ and 300-500 r / min under a nitrogen atmosphere. Then, a mixed anhydride intermediate solution was slowly added dropwise to the reaction vessel. After the addition was complete, the mixture was kept warm and stirred for 5-10 min. The reaction was continued for 30-40 min at 20-25℃ and 300-500 r / min. After the reaction was completed, anhydrous ethanol was added to terminate the reaction. The mixture was washed, purified, and dried to obtain a perfluoropolyether surfactant.

6. The method for preparing a polyether-based composite surfactant according to claim 5, characterized in that, The ratio of the amount of the diamino polyethylene glycol, trifluorotoluene, triethylamine and mixed anhydride intermediate solution is 6.0-10.0g: 50-70mL: 3-5mL: 103-143mL.

7. The method for preparing a polyether-based composite surfactant according to claim 1, characterized in that, The specific preparation process of the potassium phosphate salt described in step two is as follows: Bisphenol A polyoxyethylene ether was added to a reactor, and pyrophosphate was added at 40-50℃ and 300-500 r / min. The temperature was raised to 60-65℃ and the reaction was carried out for 2-3 hours. Deionized water was added and the reaction was carried out at 60-70℃ for 2-3 hours. The mixture was then neutralized with potassium hydroxide aqueous solution and the pH was adjusted to 8-9 to obtain potassium phosphate salt.

8. The method for preparing a polyether-based composite surfactant according to claim 7, characterized in that, The mass ratio of bisphenol A polyoxyethylene ether, pyrophosphate, and deionized water is 100-150:11.2-15.4:2.2-3.

2.

9. The method for preparing a polyether-based composite surfactant according to claim 1, characterized in that, In step three, the ratio of potassium phosphate salt, deionized water, perfluoropolyether surfactant, and silicone defoamer is 50-60g: 50-60mL: 10-20g: 0.2-0.4g.

10. The application of the polyether composite surfactant prepared by the method of any one of claims 1-9 in pesticide synergistic adjuvants.

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