A surfactant and its preparation method and application

Abstract

The application discloses a surfactant and a preparation method and application thereof, and the surfactant comprises at least one cationic single-head double-tail surfactant shown in the following formula A and at least one diacid compound shown in the following formula B. The application realizes differential deposition of the surfactant when impacting different plant hydrophobic surfaces by precisely regulating aggregate phase behavior of the cationic single-head double-tail surfactant shown in the formula A and the diacid compound shown in the formula B and utilizing the subtle difference of hydrophobicity of crop and weed leaves at different growth stages. Formula A HOOC-(CH2) n -COOH Formula B

Description

Technical Field

[0001] This invention belongs to the field of surfactant and its preparation technology, specifically relating to a surfactant, its preparation method and application. Background Technology

[0002] Surfactants possess a unique molecular structure with a hydrophilic head group and a hydrophobic tail chain, resulting in high surface / interfacial activity. This significantly reduces surface / interfacial tension and provides a range of physicochemical properties, including wetting, emulsification, foaming, solubilization, dispersion, detergency, and antistatic effects. They are widely used in daily chemicals, food, pharmaceuticals, petroleum, wastewater treatment, and biotechnology. More importantly, surfactants can interact with various other types of molecules (such as polymers and organic salt compounds) to form mixed aggregates. By controlling the molecular structure of surfactants and auxiliaries, as well as the ratio of the compound system, different aggregate forms can be formed in aqueous solutions, including globular micelles, worm-like micelles, bilayer vesicles, multilayer membrane structures, and liquid-liquid condensates.

[0003] Droplet impaction on solid surfaces is a ubiquitous and important phenomenon in nature and human society. In daily life and industrial production, droplet impaction is widely used in pesticide spraying, biomedical analysis, inkjet printing, spray cooling, anti-icing, and anti-frost applications. Droplet impaction behavior is complexly influenced by various factors, including the interaction between different forms of surfactant aggregates within the droplet and the microstructure of the solid surface. Therefore, accurately understanding and controlling the self-assembly behavior of surfactant systems is a necessary step to integrate droplet impaction into multifunctional applications and further improve efficiency, especially in pesticide spraying.

[0004] Corn is a vital economic and food crop worldwide, occupying a central position in global agricultural production and food security systems. However, goosegrass, a common weed in cornfields, competes with corn for sunlight, water, and nutrients during its seedling stage, impacting corn yield. Therefore, ensuring a bountiful corn harvest relies on the precise and efficient application of herbicides, nutrient-rich pesticides, and other pesticide formulations. However, in actual production, only a small portion of pesticides remains on the leaf surface to exert their effective effect because the leaves of both corn and goosegrass seedlings are generally hydrophobic. Currently, the main method to promote droplet deposition on the leaf surface is to add polymers or surfactants, but this method lacks selectivity. Existing adjuvants cannot guarantee that pesticides will deposit more extensively on specific leaf surfaces during application. For example, some endogenous plant hormones that aid plant growth and pesticides that combat pests and diseases need to be deposited more on corn leaves, while herbicides should be retained as much as possible on goosegrass leaves. Summary of the Invention

[0005] It is worth noting that the relative hydrophobicity of corn and goosegrass leaves reverses during the leaf growth process. To address this characteristic, this invention proposes a surfactant design approach that leverages the dynamic changes in leaf hydrophobicity to regulate the phase behavior of surfactant aggregates, thereby achieving precise deposition of active pharmaceutical ingredients on target leaves. Specifically, this invention provides a surfactant, its preparation method, and its application. The surfactant is assembled from a cationic single-headed, double-tailed surfactant (as shown in Formula A) and a diacid compound (as shown in Formula B) to obtain two aggregate morphologies: vesicles and liquid-liquid condensates. By precisely regulating the aggregate phase behavior, differential deposition of active pharmaceutical ingredients on the leaves of crops and weeds is achieved.

[0006] Based on this, the technical solution of the present invention is as follows: A surfactant comprising at least one cationic single-headed double-tailed surfactant as shown in Formula A, and at least one diacid compound as shown in Formula B.

[0007] Formula A HOOC-(CH2) n -COOH formula B Among them, R1 and R2 are the same, both being methyl; R3 and R4 may be the same or different, and are independent of each other, so choose C. 10-16 alkyl; n is an integer between 2 and 10.

[0008] According to an embodiment of the present invention, the surfactant includes two aggregate forms: vesicles and liquid-liquid condensates.

[0009] According to an embodiment of the present invention, by weight percentage (100%), it comprises at least 0.05%-0.3% of at least one cationic single-headed double-tailed surfactant of formula A and at least 0.0032%-0.62% of at least one diacid compound of formula B.

[0010] According to an embodiment of the present invention, the remainder is water or an aqueous solution containing pesticide components, with a mass percentage of 100%.

[0011] According to embodiments of the present invention, R3 and R4 may be the same or different, and are independently selected from decyl, dodecyl, tetradecyl or hexadecyl.

[0012] According to an embodiment of the present invention, n is 2, 4, 6, 8 or 10.

[0013] According to an embodiment of the present invention, the cationic single-headed double-tailed surfactant represented by Formula A is, for example, bis(dodecyl)dimethylammonium bromide (DDAB), which has a molecular structure as shown in Formula I.

[0014]

[0015] Formula I According to embodiments of the present invention, the diacid compound represented by formula B is, for example, succinic acid (DS), glutaric acid (DG), or adipic acid (DA), and its structural formulas are shown in the molecular structures of formulas II-1, II-2, and II-3, respectively.

[0016]

[0017] Formula II-1 Formula II-2 Formula II-3 According to an embodiment of the present invention, the surfactant has a pH value of 7.0-7.5.

[0018] According to an embodiment of the present invention, the content of the cationic single-headed double-tailed surfactant shown in Formula A is 0.05%-0.3%, more preferably 0.093%-0.28%, for example 0.093%, 0.1%, 0.15%, 0.19%, 0.25%, or 0.28%.

[0019] According to an embodiment of the present invention, the content of the diacid compound represented by formula B is 0.0032%-0.62%, and more preferably 0.015%-0.2%, for example 0.015%, 0.05%, 0.08%, 0.1%, 0.15% or 0.2%.

[0020] According to an embodiment of the present invention, the pesticide component is at least one selected from nitrosulfuron, corn enlargement agent, nicosulfuron, deltamethrin, and indoleacetic acid, preferably nitrosulfuron and / or corn enlargement agent.

[0021] According to an embodiment of the present invention, the concentration of the aqueous solution containing pesticide components is 0.01-0.4 wt%, preferably 0.05-0.3 wt%, for example 0.05%, 0.067%, 0.1%, 0.15%, 0.2%, 0.25% or 0.3%.

[0022] The present invention also provides a method for preparing the above-mentioned surfactant, the method comprising: The surfactant is prepared by mixing the cationic single-headed double-tailed surfactant of Formula A and the diacid compound of Formula B with water or an aqueous solution containing pesticide components, and adjusting the pH of the system to 7.0-7.5.

[0023] This invention does not impose special restrictions on the mixing temperature and time, as long as the mixing is uniform.

[0024] The present invention also provides the application of the above-mentioned surfactant in herbicides, preferably, the grass being goosegrass. Preferably, the surfactant is used to remove goosegrass from corn crops.

[0025] The beneficial effects of this invention are: This invention achieves differential deposition of surfactants when they impact the hydrophobic surfaces of different plants by precisely controlling the aggregate phase behavior of the cationic single-headed double-tailed surfactant represented by Formula A and the diacid compound represented by Formula B, and by utilizing the subtle differences in the hydrophobicity of crop and weed (e.g., goosegrass) leaves at different growth stages. Attached Figure Description

[0026] Figure 1 This is the turbidity curve of DDAB titrated with DS solution, DG solution and DA solution in Test Example 1.

[0027] Figure 2 This is a laser confocal microscope image of DDAB assembled with DS, DG, and DA to form vesicles and liquid-liquid condensed phases in Test Example 2.

[0028] Figure 3 The contact angle and adhesion force of water droplets on the leaf surfaces of corn and goosegrass at different growth stages are shown in Test Example 3.

[0029] Figure 4 for Figure 3 Scanning electron microscope images of the leaves of corn and goosegrass at different leaf stages were obtained.

[0030] Figure 5 This is a diagram showing the impact behavior of surfactant droplets impacting the leaves of corn and goosegrass at the two-leaf stage in Example 8.

[0031] Figure 6 This is a diagram showing the impact behavior of surfactant droplets impacting the leaves of corn and goosegrass at the four-leaf stage in Example 11. Detailed Implementation

[0032] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention, and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0033] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0034] Example 1 DDAB, DS, and deionized water were mixed and dissolved in the following mass percentage ratios, and the pH was adjusted to 7.0-7.5 to prepare the compound surfactant: DDAB 0.093wt% (2mM) DS 0.03wt% 99.88 wt% deionized water 2 mL of the above surfactant was sprayed onto the leaves of corn and goosegrass at the two-leaf stage. The surfactant droplets bounced off the corn leaves at the two-leaf stage and deposited on the goosegrass leaves at the two-leaf stage.

[0035] Example 2 DDAB, DG, and deionized water were mixed and dissolved in the following mass percentage ratios, and the pH was adjusted to 7.0-7.5 to prepare the compound surfactant: DDAB 0.093wt% (2mM) DG 0.03wt% 99.88 wt% deionized water 2 mL of the above surfactant was sprayed onto the leaves of corn and goosegrass at the two-leaf stage. The surfactant droplets bounced off the corn leaves at the two-leaf stage and deposited on the goosegrass leaves at the two-leaf stage.

[0036] Example 3 DDAB, DA, and deionized water were mixed and dissolved in the following mass percentage ratios, and the pH was adjusted to 7.0-7.5 to prepare the compound surfactant: DDAB 0.093wt% (2mM) DA 0.03wt% 99.88 wt% deionized water 2 mL of the above surfactant was sprayed onto the leaves of corn and goosegrass at the two-leaf stage. The surfactant droplets bounced off the corn leaves at the two-leaf stage and deposited on the goosegrass leaves at the two-leaf stage.

[0037] Example 4 DDAB, DS, and deionized water were mixed and dissolved in the following mass percentage ratios, and the pH was adjusted to 7.0-7.5 to prepare the compound surfactant: DDAB 0.19wt% (4mM) DS 0.04wt% 99.77 wt% deionized water 2 mL of the above surfactant was sprayed onto the leaves of corn and goosegrass at the two-leaf stage. The surfactant droplets could be deposited on the corn leaves at the four-leaf stage and bounce off the goosegrass leaves at the four-leaf stage.

[0038] Example 5 DDAB, DG, and deionized water were mixed and dissolved in the following mass percentage ratios, and the pH was adjusted to 7.0-7.5 to prepare the compound surfactant: DDAB 0.19wt% (4mM) DG 0.04wt% 99.77 wt% deionized water 2 mL of the above surfactant was sprayed onto the leaves of corn and goosegrass at the two-leaf stage. The surfactant droplets could be deposited on the corn leaves at the four-leaf stage and bounce off the goosegrass leaves at the four-leaf stage.

[0039] Example 6 DDAB, DA, and deionized water were mixed and dissolved in the following mass percentage ratios, and the pH was adjusted to 7.0-7.5 to prepare the compound surfactant: DDAB 0.19wt% (4mM) DA 0.04wt% 99.77 wt% deionized water 2 mL of the above surfactant was sprayed onto the leaves of corn and goosegrass at the two-leaf stage. The surfactant droplets could be deposited on the corn leaves at the four-leaf stage and bounce off the goosegrass leaves at the four-leaf stage.

[0040] Examples 7-9 The water components in Examples 1-3 were all replaced with an aqueous solution of 0.25 wt% nitrazine. The droplet impact experiment was repeated, and the droplets were still able to bounce off the corn leaf surface at the two-leaf stage and deposit on the goosegrass leaf surface at the two-leaf stage.

[0041] Examples 10-12 When the water component in Examples 4-6 was replaced with an aqueous solution of corn growth promoter at a concentration of 0.067 wt%, and the droplet impact experiment was repeated, the droplets could still be deposited on the corn leaf surface at the four-leaf stage and bounce off the goosegrass leaf surface at the four-leaf stage.

[0042] Test Example 1 Add DS solution (200 mM) dropwise to 5 mL of 2 mM DDAB solution to convert the vesicles into liquid-liquid condensates. The final volume of DS solution added is 1.2 mL. Similarly, replace the DS solution with DG solution and DA solution respectively, and repeat the above titration experiment.

[0043] By calculating the slope of the curve, the concentrations of the DS solution, DG solution, and DA solution when the vesicles transform into liquid-liquid condensed phase are 12.3 mM (the solute content in the DS solution is 0.2 wt%), 8.8 mM (the solute content in the DG solution is 0.15 wt%), and 6.7 mM (the solute content in the DA solution is 0.13 wt%), respectively.

[0044] Add 1.2 mL of DS solution (200 mM) to 5 mL of 4 mM DDAB solution to convert the vesicles into a liquid-liquid condensate. Similarly, replace the DS solution with DG and DA solutions respectively, and repeat the titration experiment.

[0045] By calculating the slope of the curve, the concentrations of the DS solution, DG solution, and DA solution when the vesicles transform into liquid-liquid condensed phase are 29.6 mM (the solute content in the DS solution is 0.48 wt%), 16.7 mM (the solute content in the DG solution is 0.29 wt%), and 15.3 mM (the solute content in the DA solution is 0.29 wt%), respectively.

[0046] Figure 1 The left figure shows the turbidity curves obtained by adding DS solution, DG solution, and DA solution dropwise to a 2 mM DDAB solution, respectively. Figure 1 The right figure shows the turbidity curves obtained by adding DS solution, DG solution, and DA solution dropwise to a 4 mM DDAB solution, respectively. Figure 1 In the figure, the vertical axis represents turbidity. In this invention, the slope of the turbidity curve becomes gentler, and observation using a laser confocal microscope reveals no vesicle morphology within the field of view.

[0047] In this invention, DDAB can form ordered aggregates such as micelles and vesicles above the critical micelle concentration (CMC), with a concentration range of 0.093 wt% to 0.28 wt%. DDAB can self-assemble into vesicles with a diameter of several hundred nanometers. Adding the diacid compound of formula B to DDAB increases the turbidity of the system. Turbidity titration was used to quantitatively study the critical concentration at which DDAB and the diacid compound of formula B assemble. Figure 1 As shown, with the addition of a diacid compound to DDAB, the turbidity of the system initially increases slightly and then decreases slowly. At this point, liquid-liquid phase separation occurs, with vesicles transforming into liquid-liquid condensates, and a vesicle-liquid condensate coexistence region exists within a certain concentration range. After the diacid compound concentration accumulates to a certain value, further addition of the diacid compound causes the turbidity to rise rapidly to near 1. At this point, the aggregates such as vesicles completely transform into liquid-liquid condensates; this concentration of the diacid compound is called the critical concentration. As the DDAB concentration increases, the critical concentration of the diacid compound increases. At the same DDAB concentration, increasing the chain length of the diacid compound decreases the critical concentration. This is because the elongation of the alkyl chain portion of the diacid compound increases the hydrophobicity of the molecule, improving its assembly ability; therefore, fewer diacid compound molecules can completely assemble with DDAB to form a liquid-liquid condensate.

[0048] Test Example 2 The system was stained with Rhodamine B, and the vesicles and liquid-liquid condensate phases were observed using a laser confocal microscope. Figure 2 These are laser confocal microscopy images of DDAB assembling with DS, DG, and DA to form vesicles and liquid-liquid condensates. Numbers 1-6 represent solutions of 1.6 mM DS (0.026 wt% solute), 1.4 mM DG (0.025 wt% solute), 0.8 mM DA (0.015 wt% solute), 32.4 mM DS (0.53 wt% solute), 24.2 mM DG (0.43 wt% solute), and 13.8 mM DA (0.26 wt% solute). In numbers 1, 2, and 6, the concentration of DDAB is 2 mM, while in numbers 3, 4, and 5, the concentration of DDAB is 4 mM. Taking No. 1 as an example, prepare 5 mL of aqueous solution containing 2 mM DDAB and 1.6 mM DS, stain the system with Rhodamine B, and observe the vesicles and liquid-liquid condensate phases using a laser confocal microscope.

[0049] Figure 2 It can be seen that the diameters of vesicles and liquid-liquid condensed phases in the coexistence region are both in the micrometer range. As the concentration of diacid compounds increases, the condensed phase increases while the number of vesicles decreases. At the same time, the size of the liquid-liquid condensed phase also increases. In the range of diacid compound content of 0.015wt%-0.03wt% (as shown in serial numbers 1-3), the diameter of the liquid-liquid condensed phase is about 3 μm. When the diacid concentration is higher than 0.2wt% (as shown in serial numbers 4-6), the size of the liquid-liquid condensed phase increases to about 10 μm.

[0050] Test Example 3 Figure 3 The contact angle of water droplets on the leaf surfaces of corn and goosegrass at different growth stages (corn two-leaf stage, corn three-leaf stage, corn four-leaf stage, goosegrass two-leaf stage, goosegrass three-leaf stage, and goosegrass four-leaf stage, respectively) is given. Figure 3 (left) and adhesion ( Figure 3 (Right) From the two-leaf stage to the four-leaf stage, the hydrophobicity of water droplets on the corn surface decreases, while the hydrophobicity on the goosegrass surface increases. Conversely, from the two-leaf stage to the four-leaf stage, the adhesion of water droplets on the corn surface gradually increases, while the hydrophobicity on the goosegrass surface weakens.

[0051] right Figure 3 Scanning electron microscopy (SEM) images of the obtained corn and goosegrass surfaces were tested, and the results are as follows: Figure 4 As shown, from the two-leaf stage to the four-leaf stage, the scale structure on the surface of corn leaves becomes sparse, while the scale structure on the surface of goosegrass leaves becomes dense.

[0052] Figure 5The image shows the impact behavior of surfactant droplets impacting the leaves of corn and goosegrass at the two-leaf stage in Example 8. The speeds of the surfactant droplets are 0ms, 2ms, 6ms, 12ms and 20ms, respectively. The surfactant droplets bounce off the leaves of corn at the two-leaf stage and are deposited on the leaves of goosegrass at the two-leaf stage.

[0053] Figure 6 The image shows the impact behavior of surfactant droplets impacting the leaves of corn and goosegrass at the four-leaf stage in Example 11. The speeds of the surfactant droplets are 0ms, 2ms, 6ms, 12ms and 20ms, respectively. The surfactant droplets are deposited on the leaves of corn at the four-leaf stage and bounce off the leaves of goosegrass at the four-leaf stage.

[0054] The embodiments of the present invention have been described above by way of example. However, the scope of protection of the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made by those skilled in the art within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A surfactant, characterized in that, It includes at least one cationic single-headed double-tailed surfactant as shown in Formula A below, and at least one diacid compound as shown in Formula B below; Formula A HOOC-(CH2) n -COOH formula B Among them, R1 and R2 are the same, both being methyl; R3 and R4 may be the same or different, and are independent of each other, so choose C. 10-16 alkyl; n is an integer between 2 and 10.

2. The surfactant according to claim 1, characterized in that, Based on a mass percentage of 100%, it comprises 0.05%-0.3% of at least one cationic single-headed double-tailed surfactant of Formula A and 0.0032%-0.62% of at least one diacid compound of Formula B.

3. The surfactant according to claim 2, characterized in that, The composition is 100% by mass, with the remainder being water or an aqueous solution containing pesticide components.

4. The surfactant according to claim 1, characterized in that, The cationic single-headed, double-tailed surfactant shown in Formula A is bis(dodecyl dimethyl)ammonium bromide, which has a molecular structure as shown in Formula I. ； Formula I The dicarboxylic acid compound shown in Formula B is succinic acid, glutaric acid, or adipic acid, and its structural formulas are shown in the following II-1, II-2, and II-3 molecular structures, respectively.

5. The surfactant according to claim 1, characterized in that, The surfactant has a pH value of 7.0-7.

5.

6. The surfactant according to claim 3, characterized in that, The pesticide ingredient is at least one of the following: nitrosulfuron-methyl, corn growth regulator, nicosulfuron, deltamethrin, and indoleacetic acid.

7. The method for preparing the surfactant according to any one of claims 1-6, characterized in that, The method includes: The surfactant is prepared by mixing the cationic single-headed double-tailed surfactant of Formula A and the diacid compound of Formula B with water or an aqueous solution containing pesticide components, and adjusting the pH of the system to 7.0-7.

5.

8. The use of the surfactant according to any one of claims 1-6 in herbicides.

9. The application according to claim 8, characterized in that, The grass in question is goosegrass.

10. The application according to claim 9, characterized in that, The surfactant is used to remove goosegrass from corn crops.

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