A PPO / PEO block carboxylate Gemini surfactant, a preparation method and application thereof

Abstract

This application belongs to the field of surfactant preparation technology, specifically relating to a Gemini surfactant containing PPO / PEO block carboxylates, its preparation method, and its applications. Using a fatty alcohol as an initiator, a PPO-PEO block fatty alcohol polyether intermediate is prepared. The block intermediate is coupled with diglycidyl ether to obtain a Gemini-type polyether intermediate with hydroxyl groups at both ends. A carboxymethylating agent is added for carboxymethylation, and after purification, the target surfactant is obtained. The surfactant of this application exhibits excellent surface activity, and the preparation method has significant advantages in terms of raw material cost and process scale-up. By adjusting the PPO / PEO block ratio, the salt resistance and environmental adaptability of the product are significantly improved, effectively broadening its application potential and reliability in fields requiring tolerance to high salinity or hard water. It also shows clear application prospects in high-ionic-strength environments with salinity fluctuations, such as in semiconductor wet processes.

Description

Technical Field

[0001] This application belongs to the field of surfactant preparation technology, specifically relating to a Gemini surfactant containing PPO / PEO block carboxylate, its preparation method, and its application. Background Technology

[0002] In the electroplating and subsequent wet processing of semiconductor copper interconnects, the plating solution often contains high concentrations of copper sulfate, sulfuric acid, and various organic additives, resulting in an extremely high ionic strength. This high ionic strength environment easily deactivates surfactants due to electrostatic shielding and salting-out, leading to a decrease in their wetting and shape control capabilities during cleaning, development, and wet etching, thus exacerbating the risk of wafer pattern collapse and defect residue. Therefore, maintaining the interfacial activity of surfactants in high-salt systems is a key challenge in the semiconductor industry.

[0003] Alcohol ether carboxylates (AECs) surfactants combine the advantages of both anionic and nonionic surfactants, possessing mild, safe, and easily degradable properties. Along with glycosyl APGs, they are considered green active ingredients of the 21st century, aligning with sustainable development principles and widely recognized as functional new products. Their molecules incorporate PPO and PEO chains, endowing them with excellent resistance to hard water, acids and alkalis, electrolytes, and high temperatures, maintaining stability under extreme conditions. However, fundamental research on alcohol ether carboxylates (AECs) remains weak; systematic data on their structure-activity relationships, interfacial adsorption behavior, and synergistic mechanisms in complex systems are lacking. Furthermore, traditional single-chain carboxylate surfactants generally exhibit high Kraff characteristics, poor water solubility, and susceptibility to Ca2+. 2+ / Mg 2+ Defects such as the easy formation of calcium and magnesium soap precipitates necessitate the addition of co-solvents or anti-precipitants on-site, increasing both cost and compatibility difficulties. CN103965854A improves the salt resistance of the system to a certain extent through the synergistic compounding of anionic and cationic surfactants. Specifically, when the total surfactant dosage is 0.3%, this compounding system can only achieve ultra-low interfacial tension under conditions of a mineralization of 10000 mg / L. This result reflects that the effect of a simple physical compounding strategy on improving the salt resistance of surfactants is relatively limited, and its effective mineralization range is insufficient to meet the requirements of more demanding high-salt environments.

[0004] Therefore, it is urgent to develop novel surfactants with intrinsic salt tolerance starting from the source of molecular structure design, in order to achieve ultra-low interfacial tension at higher mineralization levels, thereby overcoming the problem of surfactant deactivation caused by high salt. Summary of the Invention

[0005] This application designs a Gemini surfactant containing PPO / PEO block carboxylates at the molecular structure level and provides a feasible preparation method to solve the above-mentioned technical problems.

[0006] The specific technical solution is as follows: A method for preparing a Gemini surfactant containing PPO / PEO block carboxylate, comprising the following steps: S1. Preparation of block intermediate: Using fatty alcohol as an initiator, propylene oxide and ethylene oxide are added sequentially in the presence of a catalyst and a complexing agent to carry out propoxylation and ethoxylation reactions. After the reaction is completed, the mixture is aged for 10-70 min to obtain PPO-PEO block fatty alcohol polyether intermediate. The degree of polymerization of PPO is 4-10 and that of PEO is 2-15. This intermediate is referred to as block intermediate. S2. Preparation of Gemini Intermediate: After heating and alkalizing the block intermediate, it is coupled with diglycidyl ether to obtain a Gemini-type polyether intermediate with hydroxyl groups at both ends, which is referred to as Gemini intermediate. S3. Preparation of the target surfactant: After heating and alkalizing the gemini intermediate, a carboxymethylating agent is added in batches to carry out the carboxymethylation reaction. After purification, the target surfactant is obtained.

[0007] Preferably, in step S1, the propoxylation and ethoxylation reaction pressure is 0.02-0.40 MPa, the propoxylation reaction temperature is 120℃-150℃, and the ethoxylation reaction temperature is 110℃-135℃. Step S2: Heat to 40-60℃, add alkaline catalyst under nitrogen atmosphere for 0.5-3h alkalization, then add diglycidyl ether using constant pressure dropping funnel, heat to 80-120℃, and reflux for 8-14h. Step S3: Heat to 40-60℃, add alkaline catalyst for alkalization for 0.5-3h, add carboxymethylation reagent, continue heating to 70-130℃, reflux reaction for 6-16h to obtain crude product.

[0008] Preferably, the alkaline catalyst is one or more selected from NaH, metallic Na, NaOH, and KOH.

[0009] Preferably, the fatty alcohol is one or more of n-octanol, n-decanol, dodecanol, tetradecyl alcohol, hexadecyl alcohol, and octadecyl alcohol; the diglycidyl ether is one or more of ethylene glycol diglycidyl ether, butanediol diglycidyl ether, resorcinol diglycidyl ether, glycerol diglycidyl ether, and neopentyl alcohol diglycidyl ether; and the carboxymethylating agent is one or more of chloroacetic acid, bromoacetic acid, sodium chloroacetate, sodium bromoacetate, ethyl chloroacetate, and ethyl bromoacetate.

[0010] Preferably, in step S1, potassium hydroxide is used as a catalyst and 18-crown ether-6 is used as a complexing agent.

[0011] Preferably, the molar ratio of propylene oxide, ethylene oxide and fatty alcohol is (3.50-12.00):(2.00-16.00):1.00; the molar ratio of block intermediate to diglycidyl ether is (1.00-3.00):1.00; and the molar ratio of carboxymethylating agent to gemini intermediate is (2.00-5.00):1.00.

[0012] The above preparation method yields a Gemini surfactant containing PPO / PEO block carboxylate.

[0013] The PPO / PEO block carboxylate Gemini surfactant prepared in this application has a PPO degree of polymerization ratio of 0.6 to 1.25 to PPO degree of polymerization.

[0014] The PPO / PEO block carboxylate Gemini surfactant prepared in this application is used as a surfactant in high-salt environments.

[0015] The surfactants prepared in this application can be used as wetting agents for electroplating solutions or as aids in semiconductor wet processes.

[0016] Compared with the prior art, the beneficial effects of this application are as follows: (1) This application designs and synthesizes a Gemini surfactant containing PPO / PEO block carboxylates, which has excellent surface activity and can reduce the oil-water interfacial tension to 10. -2 -10 -4 The mN / m level.

[0017] (2) This application optimizes the hydrophilic-lipophilic balance by adjusting the PPO / PEO block ratio in the surfactant molecule structure. Experimental results show that the developed Gemini-type alcohol ether carboxylate surfactant E-(APO10EO8-C)2 can achieve ultra-low interfacial tension (10 mg / L) in the mineralization range of 30,000-90,000 mg / L without the addition of cosolvents or anti-precipitants, solely based on its molecular structure. -3 (on the order of mN / m). Compared with the traditional single-chain carboxylate and CN103965854A compound system, this product shows significant advantages in a wider range of mineralization, higher hard water tolerance, and a simpler formulation system, fully verifying the feasibility of the technical path of achieving intrinsic salt tolerance through molecular structure design.

[0018] (3) The surfactant prepared in this application can maintain a low interfacial tension (<0.01 mN / m) over a wide salinity range of 3%-9% NaCl. When the NaCl concentration gradually increases from 2% to 7%, the minimum IFT continues to decrease, reaching its lowest value at 7% NaCl. After that, as the salinity continues to increase to 10%, the minimum IFT slightly recovers, but still remains at 10. -2 It exhibits excellent salinity adaptability and efficient interfacial activity, and has clear application prospects in high ionic strength environments with salinity fluctuations, such as in semiconductor wet processes.

[0019] (4) This application synthesizes a Gemini surfactant with a carboxylate as the hydrophilic head group by constructing a Gemini structure and introducing a PPO / PEO block to generate a block intermediate, then reacting it with diglycidyl ether to generate a gemini intermediate, and then through a carboxymethylation route. The preparation method described in this application has significant advantages in terms of raw material cost and process scale-up. Specifically, the selected initiators, fatty alcohol, propylene oxide, ethylene oxide, and diglycidyl ether, are all bulk industrial products with stable sources and low prices. Secondly, the conditions and equipment for propoxylation, ethoxylation, and carboxymethylation are relatively mature in China, and no special equipment is required for post-processing, thus reducing the cost of waste treatment.

[0020] In summary, the surfactant of this application exhibits excellent surface activity, and the preparation method has significant advantages in terms of raw material cost and process scale-up. By adjusting the PPO / PEO block ratio, the salt resistance and environmental adaptability of the product are significantly improved, effectively broadening its application potential and reliability in fields requiring tolerance to high salinity or hard water. It also shows clear application prospects in high ionic strength environments with salinity fluctuations, such as in semiconductor wet processes. Attached Figure Description

[0021] Figure 1 This is a flow chart of the reaction of carboxylate Gemini surfactants using dodecanol as the initiator and chloroacetic acid as the carboxylation reagent.

[0022] Figure 2 The Fourier transform infrared spectra of E-(APO10EOn)2 with different PEO ratios when m=10 are shown.

[0023] Figure 3 The image shows the hydrogen nuclear magnetic resonance spectrum of E-(APO10EO2)2 prepared in Example 1.

[0024] Figure 4 Fourier transform infrared spectra of APO10EO8, E-(APO10EO8)2, and E-(APO10EO8-C)2 prepared in Example 3.

[0025] Figure 5The graph shows the dynamic interfacial tension test results of the target products in Examples 1-4 under 5% NaCl concentration. Detailed Implementation

[0026] To facilitate understanding of this application, a more detailed description is provided below with reference to the accompanying drawings and specific embodiments. However, this application can be implemented in many different forms and is not limited to the embodiments described in this specification. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0027] A Gemini surfactant containing PPO / PEO block carboxylates has the following general formula: , Wherein, POm represents propylene oxide block, EOn represents ethylene oxide block, m and n are the degree of polymerization, with m ranging from 4 to 10 and n ranging from 2 to 15; A is a fatty alcohol group, and the fatty alcohol is any one of n-octanol, n-decanol, dodecanol, tetradecyl alcohol, hexadecyl alcohol, and octadecyl alcohol; C represents a carboxymethylation introducing group, and the carboxymethylating agent is any one of chloroacetic acid, bromoacetic acid, sodium chloroacetate, sodium bromoacetate, ethyl chloroacetate, and ethyl bromoacetate; the intermediate linking group is a diglycidyl ether functional group.

[0028] Regarding molecular structure design: (1) Gemini twin skeleton Two identical PPO / PEO block fatty alcohol polyether molecules are covalently linked near their hydrophilic ends using diglycidyl ether linking groups, forming a symmetrical twin configuration with two hydrophobic chains and two hydrophilic groups. Compared to traditional single-chain surfactants, this structure shields the electrostatic repulsion between the hydrophilic head groups at the molecular level, while enhancing the synergistic hydrophobic association effect between the two hydrophobic chains, resulting in a more compact molecular arrangement at the interface and improved surface activity.

[0029] (2) PPO / PEO block hydrophobic chain Each hydrophobic chain is copolymerized from polypropylene oxide (PPO) and polyethylene oxide (PEO) blocks, with the PPO blocks being the hydrophobic portion and the PEO blocks being the hydrophilic portion. The hydrophilic PEO segments form a hydration layer in aqueous solution, preventing the charge shielding of the carboxyl groups by salt ions through steric hindrance, thus maintaining the molecule's water solubility even under high salinity conditions. When the PEO hydration layer is compressed in a high-salt environment, the hydrophobicity of the PPO blocks increases accordingly, compensating for the driving force of interfacial adsorption and allowing the molecule to still effectively adsorb at the interface. Therefore, by controlling the degree of polymerization ratio of PO / EO, the hydrophilic-lipophilic balance of the molecule can be precisely adjusted, while simultaneously endowing the molecule with salinity adaptability: in a high-salt environment, the hydration layer of the PEO chain is compressed, the overall hydrophobicity of the molecule increases, and it is more easily adsorbed at the oil-water interface.

[0030] (3) Hydrophilic end groups of carboxylate The hydroxyl groups at the ends of the block polyether are converted into sodium carboxylate groups (-COO) via chloroacetic acid carboxylation. - Na + (), as an anionic hydrophilic group. This group not only provides strong hydrophilicity, but also has pH-responsive characteristics: it is completely ionized under alkaline conditions, and the molecule exhibits a geminal anionic configuration, resulting in the highest interfacial activity; under acidic conditions, it is partially protonated to carboxylic acid, and the molecule's hydrophilicity decreases, enabling reversible switching between emulsification and demulsification.

[0031] Combination Figure 1 The preparation method is as follows: S1. Preparation of Block Intermediates: Using fatty alcohols as initiators, propylene oxide and ethylene oxide are added sequentially in the presence of a catalyst and a complexing agent to carry out propoxylation and ethoxylation reactions, respectively, to obtain PPO-PEO block fatty alcohol polyether intermediates. The degree of polymerization of PPO is 4-10, and that of PEO is 2-15. This intermediate is simply referred to as a block intermediate. Figure 1 Understanding the products of step (a) of the reaction.

[0032] Specifically, a fatty alcohol is added as an initiator and potassium hydroxide as a catalyst to a polymerization reactor, with 18-crown ether-6 as a complexing agent. Propanylation and ethoxylation reactions are carried out under a certain pressure. After the reaction is completed, the mixture is aged for a period of time to prepare APOmEOn, where m is 4-10, n is 2-15, and A represents the fatty alcohol group. Fatty alcohols are one of the following: n-octanol, n-decanol, dodecanol, tetradecyl alcohol, hexadecyl alcohol, and octadecyl alcohol; The pressure is 0.02-0.40 MPa, the propoxylation reaction temperature is 120℃-150℃, and the ethoxylation reaction temperature is 110℃-135℃. Aging for a period of time refers to 10-70 minutes, which can eliminate active centers and make the product more stable; The added potassium hydroxide is 2‰ - 6‰ of the total mass of fatty alcohol and propylene oxide; the molar ratio of added 18-crown ether-6 to added potassium hydroxide is (1.00-1.50):1.00; the molar ratio of added propylene oxide to fatty alcohol is (3.50-12.00):1.00; and the molar ratio of added ethylene oxide to fatty alcohol is (2.00-16.00):1.00.

[0033] S2. Preparation of Gemini Intermediates: After alkalizing the block intermediate by heating, it undergoes a coupling reaction with diglycidyl ether to obtain a Gemini-type polyether intermediate with hydroxyl-terminated ends. This intermediate is simply referred to as the Gemini intermediate. Figure 1 Understanding the products of step (b) of the reaction.

[0034] Specifically, a certain mass of APOmEOn is added to a four-necked flask, heated to a certain temperature, and then a certain mass of alkaline catalyst is added under a nitrogen atmosphere for a period of time for alkalization. Subsequently, a certain mass of diglycidyl ether is added using a constant-pressure dropping funnel, and the mixture is heated to the reaction temperature and refluxed for a certain time to obtain E-APOmEOn, where E represents the dihydroxy polyether backbone. Wherein: Diglycidyl ether is one of ethylene glycol diglycidyl ether, butylene glycol diglycidyl ether, resorcinol diglycidyl ether, glycerol diglycidyl ether, or neopentyl alcohol diglycidyl ether; The temperature is raised to a certain level, which is 40-60℃. The alkaline catalyst is one or more of NaH, metallic Na, NaOH, and KOH. The alkalization period is 0.5-3 hours. The reaction temperature is 80-120℃, and the reflux reaction time is 8-14 hours. The molar ratio of APOmEOn to alkaline catalyst is (1.00-6.00):1.00, and the molar ratio of APOmEOn to diglycidyl ether is (1.00-3.00):1.00.

[0035] S3. Preparation of the target surfactant: After alkalizing the gemini intermediate by heating, a carboxymethylating agent is added to carry out a carboxymethylation reaction. After purification, the target surfactant is obtained. Figure 1 Understanding the products of step (c) of the reaction.

[0036] Specifically, a certain mass of E-APOmEOn was added to a three-necked flask, and after heating to a certain temperature, a certain mass of alkaline catalyst was added for alkalization for a period of time. Then, a certain mass of carboxymethylating agent was added in batches, and the temperature was further raised to the reaction temperature and refluxed for a period of time to obtain the crude product. The product was neutralized to pH 10 with sodium hydroxide and then hot-filtered multiple times with anhydrous ethanol to obtain the E-(APOmEOn-C)2 surfactant, where C represents an oxygen-containing carboxymethylating group. Wherein: The carboxymethylating agent is one or more of chloroacetic acid, bromoacetic acid, sodium chloroacetate, sodium bromoacetate, ethyl chloroacetate, and ethyl bromoacetate, preferably chloroacetic acid; The temperature is raised to a certain level, which is 40-60℃. The alkaline catalyst is one or more of NaH, metallic Na, NaOH, and KOH. The alkalization period is 0.5-3 hours. The reaction temperature refers to 70-130℃, and the reflux reaction time refers to 6-16 hours. The molar ratio of the added alkaline catalyst to E-APOmEOn is (2.00-4.00):1.00, and the molar ratio of the added carboxymethylating agent to E-APOmEOn is (2.00-5.00):1.00; In some embodiments, the carboxymethylating agent is added in small, multiple doses, such as in two separate additions: the first half is added, and the remaining half is added 30 minutes later. This ensures more thorough contact, controls the reaction rate, and avoids localized overconcentration. Adding a large amount of reactant at once can easily lead to excessively high local concentrations, triggering violent side reactions or generating byproducts. Using a small, multiple-dose approach allows each added material to disperse rapidly and be completely consumed, keeping the reaction in a pseudo-steady state and significantly improving the selectivity of the main product.

[0037] The following are specific examples: Example 1: A method for preparing a Gemini surfactant containing PPO / PEO block carboxylates, the method comprising: S1. Set the reactor temperature to 80℃ and begin preheating. Then, add 140.6g of dodecanol as an initiator, along with 1.5633g of potassium hydroxide as a catalyst and 6.8643g of 18-crown ether-6 as a complexing agent. Add 482.26g of propylene oxide at 130℃ to carry out a propoxylation reaction, and add 66.52g of ethylene oxide at 125℃ to carry out an ethoxylation reaction. After the addition is complete, raise the temperature to 140℃ and age for 30 minutes to obtain APO10EO2. S2. Add 30.22 g of APO10EO2 to a four-necked flask, and after the temperature reaches 60 °C, add 0.3083 g of NaH under a nitrogen atmosphere to alkalize for 2 h. After alkalization, add 3.0487 g of ethylene glycol diglycidyl ether using a constant pressure dropping funnel. After heating to 90 °C and reacting for 12 h, add 10 ml of HCl to quench the reaction, yielding E-(APO10EO2)2; S3. Add 20.43 g of E-APO10EO2 to a four-necked flask. After the temperature reaches 70 °C, add 0.9385 g of NaOH in portions under a nitrogen atmosphere and alkalize for 2 h. After alkalization, add 3.3249 g of chloroacetic acid as a carboxymethylating agent, in two portions (half is added first, and the remaining half is added after 30 min). After refluxing at 85 °C for 8 h, a crude product is obtained. Add hot anhydrous ethanol to dissolve the product, filter to remove impurities, and obtain the E-(APO10EO2-C)2 surfactant.

[0038] Example 2: A Gemini surfactant containing PPO / PEO block carboxylates and its preparation method, the method comprising: S1. Set the reactor temperature to 80℃ and begin preheating. Then, add 143.7g of tetradecyl alcohol as an initiator, along with 1.7762g of potassium hydroxide as a catalyst and 8.3708g of 18-crown ether-6 as a complexing agent. Add 157.98g of propylene oxide at 130℃ to initiate a propoxylation reaction, and add 511.94g of ethylene oxide at 125℃ to initiate an ethoxylation reaction. After the addition is complete, raise the temperature to 140℃ and age for 30 minutes to obtain APO4EO15. S2. Add 60.17 g of tetradecyl alcohol polyether block APO4EO15 to a four-necked flask. After reaching 60 °C, add 0.4038 g of NaH under a nitrogen atmosphere and alkalize for 2 h. After alkalization, add 3.8264 g of resorcinol diglycidyl ether using a constant pressure dropping funnel. After reacting at 90 °C for 12 h, add 10 ml of HCl to quench the reaction, yielding E-(APO4EO15)2; S3. Add 9.9503 g of E-APO4EO15 to a four-necked flask. After the temperature reaches 65°C, add 0.3355 g of NaOH in batches under a nitrogen atmosphere and alkalize for 2 h. After alkalization, add 1.8783 g of chloroacetic acid as a carboxymethylation reagent in small amounts multiple times. After the temperature reaches 90°C, reflux for 9 h to obtain a crude product. Add hot anhydrous ethanol to dissolve the product, filter to remove impurities, and obtain the surfactant E-(APO4EO15-C)2.

[0039] Example 3: A Gemini surfactant containing PPO / PEO block carboxylates and its preparation method, the method comprising: S1. Set the reactor temperature to 80℃ and begin preheating. Then, add 121.4g of dodecanol as an initiator, along with 1.5008g of potassium hydroxide as a catalyst and 7.0980g of 18-crown ether-6 as a complexing agent. Add 416.48g of propylene oxide at 130℃ to carry out a propoxylation reaction, and add 229.75g of ethylene oxide at 125℃ to carry out an ethoxylation reaction. After the addition is complete, raise the temperature to 140℃ and age for 30 minutes to obtain fatty alcohol polyether block APO10EO8. S2. 59.78 g of APO10EO8 was added to a four-necked flask. After the temperature reached 60 °C, 0.4427 g of NaH was added under a nitrogen atmosphere for alkalization for 2 h. After alkalization, 3.3832 g of ethylene glycol diglycidyl ether was added using a constant pressure dropping funnel. After reacting at 90 °C for 12 h, 10 ml of HCl was added to quench the reaction, yielding E-(APO10EO8)2; S3. Add 17.80 g of E-APO10EO8 to a four-necked flask. After the temperature reaches 70 °C, add 0.6731 g of NaOH in batches under a nitrogen atmosphere to alkalize for 2 h. After alkalization, add 2.2054 g of chloroacetic acid as a carboxymethylation reagent in two batches (add half first, and add the remaining half after 30 min). After the temperature reaches 85 °C, reflux for 8 h to obtain a crude product. Add hot anhydrous ethanol to dissolve the product, filter to remove impurities, and obtain the surfactant E-(APO10EO8-C)2.

[0040] Example 4: A Gemini surfactant containing PPO / PEO block carboxylates and its preparation method, the method comprising: S1. Set the reactor temperature to 80℃ and begin preheating. Then, add 133.6g of dodecanol as an initiator, along with 1.4993g of potassium hydroxide as a catalyst and 7.8812g of 18-crown ether-6 as a complexing agent. Add 249.96g of propylene oxide at 130℃ to initiate a propoxylation reaction, and add 316.04g of ethylene oxide at 125℃ to initiate an ethoxylation reaction. After the addition is complete, raise the temperature to 140℃ and age for 30 minutes to obtain fatty alcohol polyether block APO6EO10. S2. Add 58.12 g of APO6EO10 to a four-necked flask, and after the temperature reaches 60 °C, add 0.5512 g of NaH under a nitrogen atmosphere to alkalize for 2 h. After alkalization, add 4.3062 g of neopentyl glycol diglycidyl ether using a constant pressure dropping funnel. After heating to 90 °C and reacting for 12 h, add 10 ml of HCl to quench the reaction, yielding E-(APO6EO10)2; S3. Add 17.80 g of E-APO6EO10 to a four-necked flask. After the temperature reaches 75 °C, add 0.5633 g of NaOH in batches under a nitrogen atmosphere and alkalize for 2 h. After alkalization, add 2.8759 g of chloroacetic acid as a carboxymethylation reagent in two parts: first add half, and then add the remaining half after 30 min. After the temperature reaches 85 °C, reflux for 8 h to obtain a crude product. Add hot anhydrous ethanol to dissolve the product, filter to remove impurities, and obtain the surfactant E-(APO6EO10-C)2.

[0041] like Figure 2 As shown, in the range of 4000~400 cm -1 The FT-IR of E-APO10EOn was measured using a Thermo Fisher Scientific Nicolet IS10 infrared spectrometer. Specifically, at 3470.64 cm⁻¹ -1 -3506.83cm -1The absorption peak is attributed to the -OH stretching vibration, at 2968.75 cm⁻¹. -1 -2970.58cm -1 The absorption peak attributable to the antisymmetric stretching vibration of CH in -CH3 is 2925.71 cm⁻¹. -1 -2926.95cm -1 The antisymmetric absorption peak attributable to CH in -CH2 is located at 2859.24 cm⁻¹. -1 -2865.63cm -1 The absorption peak is attributed to the symmetric stretching vibration of CH in -CH3, at 1457.09 cm⁻¹. -1 -1457.96cm -1 The antisymmetric bending absorption peak attributable to CH in -CH3 or -CH2, 1373.12 cm⁻¹. -1 -1373.80cm -1 The symmetrically bent absorption peak, attributed to CH in -CH3, is located at 1107.94 cm⁻¹. -1 -1109.82cm -1 The absorption peak is attributed to COC, at 1009.55 cm⁻¹. -1 -1014.16cm -1 The absorption peak is attributed to the rocking vibration of CH in -CH3. By analyzing the FT-IR test results of the intermediate E-(APO10EOn)2, it can be preliminarily determined that the synthesized intermediate is consistent with the expected structure.

[0042] like Figure 3 As shown, the 1H NMR of E-(APO10EO2)2 was determined using CDCl3 as solvent and a Bruker Avance 400 MHz NMR spectrometer. The chemical shift δ=5.29 represents the proton peak of -OH; δ=3.2–3.8 represents the proton peak of -C2H4O- in the polyether chain; δ=2.3 represents the proton peak of -CH- linked to the hydroxyl group; δ=1.20–1.64 represents the proton peak of -CH2- in the long aliphatic chain; and δ=0.89 represents the proton peak of -CH3 at the end of the long aliphatic chain. Analysis of the 1H-NMR results of the intermediate E-(APO10EO2)2 preliminarily indicates that the synthesized intermediate matches the expected structure.

[0043] like Figure 4 As shown, Fourier transform infrared spectroscopy analysis of the target product in Example 3 confirmed that the synthesized product was the target product. Compared with the intermediate products APO10EO8 and E-(APO10EO8)2, E-(APO10EO8-C)2 showed better performance at a wavenumber of 1610 cm⁻¹. -1 The characteristic absorption peak of carboxylate appeared at 3500 cm⁻¹. -1The hydroxyl peak at the point was significantly weakened or even disappeared. By analyzing the FT-IR test results of intermediates APO10EO8 and E-(APO10EO8)2, it can be determined that the synthesized product is consistent with the expected structure, thus proving that the synthesized product is the target product.

[0044] like Figure 5 As shown, the block ratio of polyoxypropylene (PO) and polyoxyethylene (EO) is a key parameter determining its interfacial properties. By comparing the interfacial tension test results of different examples at a 5% salt concentration, this structure-property relationship can be clearly revealed: only Examples 3 and 4, with their optimal PO / EO ratio, can reduce the interfacial tension to 10. -3 The interfacial tension values ​​in Examples 1 and 2 are on the order of mN / m, while due to the ratio deviation, the interfacial tension values ​​can only be reduced to 10. -2 The PO / EO block surfactant developed in this study can still reduce the interfacial tension to 10 N / m under 5% high-salt conditions. -3 This property, on the order of mN / m, gives it the potential to be used as a wetting agent in electroplating solutions, effectively reducing the interfacial energy between the plating solution and the substrate and improving the uniformity of the filling of aspect ratio structures.

[0045] Interfacial tension testing: The interfacial properties of the E-(APO10EO8-C)2 surfactant synthesized in Example 3 were investigated using a TX-600 rotating drop interfacial tensiometer (45℃, 5000rpm). The results showed that this surfactant maintained a low interfacial tension (<0.01 mN / m) over a wide salinity range of 3%-9% NaCl, exhibiting excellent salinity adaptability and high interfacial activity. Specifically, as the NaCl concentration gradually increased from 2% to 7%, the minimum interfacial tension (IFT) continuously decreased, reaching a minimum value of 9.93 × 10⁻⁶ at 7% NaCl. -4 mN / m; thereafter, as salinity continued to rise to 10%, the lowest IFT, although slightly rebounding, remained at 10. -2 The mN / m range indicates its promising application prospects in high-ionic-strength environments with fluctuating salinity, such as in semiconductor wet processes. Mechanism Explanation: This gemini surfactant uses diglycidyl ether as a linking group, covalently connecting two long-chain hydrophobic alkyl tails to a hydrophilic carboxylate head group, forming a symmetrical gemini configuration. The embedded PPO / PEO blocks further regulate the hydrophilic-lipophilic balance. At the oil-water interface, the molecules spontaneously align with the hydrophobic tails facing the oil phase and the hydrophilic carboxylate group facing the water phase. Because the linking group fixes the two hydrophilic head groups in adjacent positions within the molecule, it effectively suppresses electrostatic repulsion between the head groups, resulting in a densely packed adsorbed layer and significantly increased packing density. This allows the oil-water interfacial tension to be reduced to 10 even at relatively low concentrations. -3The concentration is on the order of mN / m. Secondly, the introduction of the PPO / PEO block endows the molecule with unique salt resistance advantages: the flexibility of the PEO chain maintains the spatial stability of the head group region in high-salt environments, while the PPO chain moderately regulates the hydrophilicity-hydrophobicity balance of the molecule, avoiding phase separation or precipitation caused by salt ions compressing the electric double layer; simultaneously, the twin configuration brings the two carboxylate groups closer together within the molecule, reducing the local charge density around each individual head group and weakening the resistance to Na+. + The synergistic effect of the above structural features enables this surfactant to maintain stable ultra-low interfacial tension even in high-salt environments of 3%–9%.

[0046] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

Claims

1. A method for preparing a Gemini surfactant containing PPO / PEO block carboxylates, characterized in that, Includes the following steps: S1. Preparation of block intermediate: Using fatty alcohol as an initiator, propylene oxide and ethylene oxide are added sequentially in the presence of a catalyst and a complexing agent to carry out propoxylation and ethoxylation reactions. After the reaction is completed, the mixture is aged for 10-70 min to obtain PPO-PEO block fatty alcohol polyether intermediate. The degree of polymerization of PPO is 4-10 and that of PEO is 2-15. This intermediate is referred to as block intermediate. S2. Preparation of Gemini Intermediate: After heating and alkalizing the block intermediate, it is coupled with diglycidyl ether to obtain a Gemini-type polyether intermediate with hydroxyl groups at both ends, which is referred to as Gemini intermediate. S3. Preparation of the target surfactant: After heating and alkalizing the gemini intermediate, a carboxymethylating agent is added in batches to carry out the carboxymethylation reaction. After purification, the target surfactant is obtained.

2. The preparation method according to claim 1, characterized in that, Step S1: The propoxylation and ethoxylation reaction pressure is 0.02-0.40 MPa, the propoxylation reaction temperature is 120℃-150℃, and the ethoxylation reaction temperature is 110℃-135℃; Step S2: Heat to 40-60℃, add alkaline catalyst under nitrogen atmosphere for 0.5-3h alkalization, then add diglycidyl ether using constant pressure dropping funnel, heat to 80-120℃, and reflux for 8-14h. Step S3: Heat to 40-60℃, add alkaline catalyst for alkalization for 0.5-3h, add carboxymethylation reagent, continue heating to 70-130℃, reflux reaction for 6-16h to obtain crude product.

3. The preparation method according to claim 2, characterized in that, The alkaline catalyst is one or more of NaH, metallic Na, NaOH, and KOH.

4. The preparation method according to claim 1, characterized in that, The fatty alcohol is one or more of n-octanol, n-decanol, dodecanol, tetradecyl alcohol, hexadecyl alcohol, and octadecyl alcohol; the diglycidyl ether is one or more of ethylene glycol diglycidyl ether, butanediol diglycidyl ether, resorcinol diglycidyl ether, glycerol diglycidyl ether, and neopentyl alcohol diglycidyl ether; the carboxymethylating agent is one or more of chloroacetic acid, bromoacetic acid, sodium chloroacetate, sodium bromoacetate, ethyl chloroacetate, and ethyl bromoacetate.

5. The preparation method according to claim 1, characterized in that, In step S1, potassium hydroxide is used as a catalyst; 18-crown ether-6 is used as a complexing agent.

6. The preparation method according to claim 1, characterized in that, The molar ratio of propylene oxide, ethylene oxide and fatty alcohol is (3.50-12.00): (2.00-16.00): 1.00; the molar ratio of block intermediate to diglycidyl ether is (1.00-3.00): 1.00; and the molar ratio of carboxymethylating agent to gemini intermediate is (2.00-5.00): 1.

00.

7. A Gemini surfactant containing PPO / PEO block carboxylate, prepared by any one of the preparation methods described in claims 1-6.

8. The preparation method according to claim 7, characterized in that, In Gemini surfactants containing PPO / PEO block carboxylates, the ratio of the degree of polymerization of PPO to that of PEO is 0.6 to 1.

25.

9. The application of the PPO / PEO block carboxylate Gemini surfactant according to claim 7, characterized in that, Used as a surfactant in high-salt environments.

10. The application according to claim 9, characterized in that, The surfactant is used as a wetting agent for electroplating solutions or as an aid in semiconductor wet processes.

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