Oligomeric surfactant, preparation method thereof and application thereof as adjuvant for targeted deposition herbicide

Abstract

The invention discloses an oligomeric surfactant, a preparation method thereof and an application thereof as a targeted deposition herbicide adjuvant. The non-covalently constructed oligomeric surfactant is prepared from the following raw materials: dialkyl dimethyl ammonium bromide and tetradecanedioic acid, a dynamic oligomeric surfactant formed by dialkyl dimethyl ammonium bromide and tetradecanedioic acid; the alkyl group is selected from an alkyl chain with a carbon number of not less than 6. The oligomeric surfactant can be used as a targeted deposition herbicide adjuvant. When used for weed control, the herbicide droplets containing the oligomeric surfactant have low surface tension and form an aggregate structure that is easily entangled on the surface of leaves. Experiments have shown that the droplets are more likely to be deposited on super-hydrophobic barnyard grass leaves, and are almost not deposited on rice leaves with stronger super-hydrophobicity, thereby achieving targeted deposition on barnyard grass leaves.

Description

Technical Field

[0001] The invention belongs to the field of pesticide adjuvants, and in particular relates to a non-covalently constructed oligomeric surfactant, a preparation method thereof, and an application thereof as a targeted deposition herbicide adjuvant. Background Art

[0002] Pesticides are an important guarantee for the stable and high yield of grain, and can reduce the global grain loss by about 30% every year. As an important means of human intervention in crop growth, herbicides eliminate weeds that compete with crops, thereby ensuring the living space of crops and increasing crop yields. However, due to the influence of convergent evolution, crops and weeds in the same area usually have very similar leaf surface microstructures, resulting in very small differences in their leaf surface contact angles with water (with similar hydrophobic or superhydrophobic properties). Therefore, herbicides will have adverse effects on crops while removing weeds, resulting in crop yield reduction. Even for crops that have been genetically engineered, the use of large amounts of pesticides will cause pesticide molecules to accumulate on the surface of these crops' leaves and inside their rhizomes, which will not only lead to high costs for the use of pesticides, but will also cause serious food safety issues and threaten human health.

[0003] Rice is one of the three major food crops in the world and the most important food crop in my country, with its output accounting for more than 50% of the country's total output. As a typical mimic weed of rice, barnyard grass has always been the most widespread and most harmful malignant weed in rice fields. As a typical C4 weed, barnyard grass has stronger photosynthesis and a faster growth rate, making it difficult for rice to compete with it. The characteristics of barnyard grass are highly similar to those of rice, making it difficult to remove them through manual identification. The extremely similar leaf morphology and complex surface microstructure also make the leaves of both plants superhydrophobic, with very little difference in contact angles. Spraying herbicides to remove barnyard grass will also cause damage to rice crops. Therefore, the development of a herbicide adjuvant that can be targeted and selectively deposited on barnyard grass leaves has become a hot and difficult issue that urgently needs to be solved. Summary of the invention

[0004] The present invention provides a non-covalently constructed oligomeric surfactant, which is prepared from the following raw materials: dialkyl dimethyl ammonium bromide and tetradecanedioic acid;

[0005] The dialkyldimethylammonium bromide and tetradecanedioic acid form a dynamic oligomeric surfactant;

[0006] The alkyl group is selected from an alkyl chain having no less than 6 carbon atoms, such as an alkyl chain having 7 to 20 carbon atoms. Exemplarily, the alkyl group is selected from an alkyl chain having 8, 10, 12, 14 or 16 carbon atoms.

[0007] According to an embodiment of the present invention, the molar ratio of the dialkyldimethylammonium bromide to tetradecanedioic acid is in the range of 1:1 to 4:1, such as 2:1 or 3:1.

[0008] According to an embodiment of the present invention, the dialkyl dimethyl ammonium bromide is selected from dioctadecyl dimethyl ammonium bromide, didecyl dimethyl ammonium bromide, didodecyl dimethyl ammonium bromide, ditetradecyl dimethyl ammonium bromide, and dihexadecyl dimethyl ammonium bromide, and has a cationic structure as shown in Formula I from left to right:

[0009]

[0010] According to an embodiment of the present invention, the tetradecanedioic acid has a structure as shown in Formula II:

[0011]

[0012] According to an embodiment of the present invention, the non-covalently constructed oligomeric surfactant further comprises a solvent, and preferably the solvent is water.

[0013] According to an embodiment of the present invention, the pH of the non-covalently constructed oligomeric surfactant is 7-13, such as 8, 9, 10, 11, or 12.

[0014] According to an exemplary embodiment of the present invention, in the non-covalently constructed oligomeric surfactant, the concentration of the dialkyl dimethyl ammonium bromide is 50-200 mM, and the concentration of the tetradecanedioic acid is 25-100 mM; for example, the concentration of the dialkyl dimethyl ammonium bromide is 100 mM, and the concentration of the tetradecanedioic acid is 50 mM.

[0015] The present invention further provides a method for preparing the above-mentioned non-covalently constructed oligomeric surfactant, comprising the following steps: mixing a dialkyl dimethyl ammonium bromide aqueous solution and a tetradecanedioic acid aqueous solution to obtain the non-covalently constructed oligomeric surfactant.

[0016] According to an embodiment of the present invention, the dialkyldimethylammonium bromide and tetradecanedioic acid have the selection and ratio as shown above.

[0017] According to an embodiment of the present invention, the dialkyldimethylammonium bromide aqueous solution is a colorless transparent solution.

[0018] According to an embodiment of the present invention, the tetradecanedioic acid aqueous solution is a colorless and transparent solution.

[0019] According to an embodiment of the present invention, the dialkyldimethylammonium bromide aqueous solution and the tetradecanedioic acid aqueous solution are combined in a volume ratio of 1:1.

[0020] According to an embodiment of the present invention, the concentration of the dialkyldimethylammonium bromide aqueous solution is 50-200 mM, for example, 100 mM.

[0021] According to an embodiment of the present invention, the concentration of the tetradecanedioic acid aqueous solution is 25-100 mM, for example, 50 mM.

[0022] According to an embodiment of the present invention, the concentration of the dialkyldimethylammonium bromide aqueous solution can be obtained by diluting a high concentration (eg, 0.5 to 5 M, such as 1 M, 2 M, 3 M) aqueous solution.

[0023] According to an embodiment of the present invention, the concentration of the tetradecanedioic acid aqueous solution can be obtained by diluting a high concentration (eg, 0.25 to 2.5 M, such as 0.5 M, 1 M, 1.5 M) aqueous solution.

[0024] According to an embodiment of the present invention, the temperature of the mixed solution may be 15 to 40° C., for example, 25° C.; the mixing time may be 3 to 10 minutes, for example, 5 minutes.

[0025] The present invention also provides the use of the non-covalently constructed oligomeric surfactant as a targeted deposition herbicide adjuvant; preferably, the use of the non-covalently constructed oligomeric surfactant as a targeted deposition herbicide adjuvant on weed leaves.

[0026] According to an embodiment of the present invention, the weeds are barnyard grass.

[0027] The present invention also provides a herbicide or a herbicide adjuvant containing the non-covalently constructed oligomeric surfactant.

[0028] According to an embodiment of the present invention, the herbicide includes the original drug and the above-mentioned non-covalently constructed oligomeric surfactant, for example, the original drug is cyhalofop-butyl.

[0029] According to an embodiment of the present invention, the molar ratio of the prodrug to the non-covalently constructed oligomeric surfactant is in the range of 1:2 to 2:1.

[0030] According to an embodiment of the present invention, the concentration of the technical drug in the herbicide is 25-100 mM, for example, 50 mM.

[0031] The present invention also provides an aggregate formed by self-assembly of the above non-covalently constructed oligomeric surfactant.

[0032] Beneficial Effects

[0033] The non-covalently constructed oligomeric surfactant provided by the present invention can be used as a targeted deposited herbicide adjuvant. When used for weed control, the herbicide droplets containing the oligomeric surfactant have low surface tension and form an aggregate structure that is easily entangled on the surface of leaves. Experiments have shown that the droplets are more likely to be deposited on super-hydrophobic barnyard grass leaves, but almost not on rice leaves with stronger super-hydrophobicity. That is, it can greatly reduce the deposition of herbicides on rice crop leaves and reduce the accumulation of herbicide residues in rice crops; increase the deposition efficiency of herbicide solutions on barnyard grass weeds, greatly reduce the number of spraying herbicides, and significantly reduce the damage of lost pesticides to the ecological environment.

[0034] The non-covalently constructed oligomeric surfactant of the present invention has an application temperature of 15-40° C., which is suitable for field operations. The preparation process is simple, the time required is short, and the use method is simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The appearance of water and each solution prepared; Ⅰ. Water; Ⅱ. 100mM tetradecanedioic acid aqueous solution; Ⅲ. 50mM ditetradecyl dimethyl ammonium bromide aqueous solution; Ⅳ. Aqueous solution of 100mM tetradecanedioic acid and 50mM ditetradecyl dimethyl ammonium bromide mixed in a volume ratio of 1:1;

[0036] Figure 2 This is a microscopic image of the mixed ditetradecyl dimethyl ammonium bromide solution and tetradecanedioic acid aqueous solution under a cryo-scanning electron microscope;

[0037] Figure 3 This is a real picture of the impact of 200 micron droplets on rice and barnyard grass leaves;

[0038] Figure 4 The bar graph shows the comparison of deposition efficiency when sprayed on rice and barnyard grass leaves. DETAILED DESCRIPTION

[0039] The technical scheme of the present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only exemplary descriptions and explanations 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 included in the scope that the present invention is intended to protect.

[0040] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0041] In the following examples and comparative examples, the deposition efficiency is obtained by the following method:

[0042] A heat flux sensor is used to monitor and record the changes in the evaporation heat flux of the retained liquid deposited on the blade surface, and the time integral of the evaporation process is multiplied by the evaporation enthalpy coefficient of unit mass of water. The mass of the retained liquid is calculated, and the ratio of the mass of the retained liquid to the total mass of the spray droplets is the deposition efficiency of the spray droplets.

[0043] In the following examples and comparative examples, the temperature of the mixture of the non-covalently constructed oligomeric surfactant targeted deposition aid solution and the cyhalofop-butyl herbicide original drug during spraying is 15-40°C.

[0044] Example 1

[0045] Prepare 100mM ditetradecyl dimethyl ammonium bromide aqueous solution (such as Figure 1 II) and 50 mM tetradecanedioic acid aqueous solution (as Figure 1 III), the above two aqueous solutions were mixed at room temperature in a volume ratio of 1:1, the pH was adjusted to 8, the ultrasonic power was adjusted to 10W, and the ultrasonic was performed for 5 minutes to obtain a non-covalently constructed oligomeric surfactant targeted deposition aid solution (such as Figure 1 The morphology of oligomeric surfactant aggregates is shown in Figure 2 As shown in the figure, it presents an obvious three-dimensional network structure, which is conducive to its entanglement on the microstructure of the leaf surface and promotes the deposition and spreading of droplets. 50mM cyhalofop-butyl herbicide original drug (99%) was added to the oligomeric surfactant targeted deposition aid solution obtained by non-covalent construction and sprayed on rice and barnyard grass leaves. The droplets bounced and splashed on the surface of rice leaves, while they were deposited on the surface of barnyard grass leaves (as shown in the figure). Figure 3 As shown in FIG. 1 ), the oligomeric surfactant solution is deposited on the barnyard grass leaves in a targeted manner. The deposition efficiency of the droplets was tested, and the deposition efficiency of the droplets on the rice and barnyard grass leaves was 4.5% and 96.4%, respectively.

[0046] Example 2

[0047] 100mM dioctaalkyl dimethyl ammonium bromide aqueous solution and 50mM tetradecanedioic acid aqueous solution were prepared respectively, and the above two aqueous solutions were mixed at a volume ratio of 1:1 at room temperature, and the pH was adjusted to 8. The ultrasonic power was adjusted to 10W, and the ultrasonic was performed for 5 minutes to obtain a non-covalently constructed oligomeric surfactant targeted deposition aid solution. 50mM cyhalofop-butyl herbicide original drug (99%) was added to the obtained non-covalently constructed oligomeric surfactant targeted deposition aid solution, and sprayed on rice and barnyard grass leaves. The droplets can rebound on the surface of the rice leaves and deposit on the surface of the barnyard grass leaves. Targeted deposition of the oligomeric surfactant solution on the barnyard grass leaves was achieved. The deposition efficiency of the droplets was tested, and the deposition efficiency of the droplets on the rice and barnyard grass leaves was 1.2% and 18.0%, respectively.

[0048] Example 3

[0049] 100mM didecyldimethylammonium bromide aqueous solution and 50mM tetradecanedioic acid aqueous solution were prepared respectively, and the above two aqueous solutions were mixed in a volume ratio of 1:1 at room temperature, and the pH was adjusted to 8. The ultrasonic power was adjusted to 10W, and the ultrasonic was performed for 5 minutes to obtain a non-covalently constructed oligomeric surfactant targeted deposition aid solution. 50mM cyhalofop-butyl herbicide original drug (99%) was added to the obtained non-covalently constructed oligomeric surfactant targeted deposition aid solution, and sprayed on rice and barnyard grass leaves. The droplets can rebound on the surface of the rice leaves and deposit on the surface of the barnyard grass leaves. Targeted deposition of the oligomeric surfactant solution on the barnyard grass leaves was achieved. The deposition efficiency of the droplets was tested, and the deposition efficiency of the droplets on the rice and barnyard grass leaves was 1.4% and 20.3%, respectively.

[0050] Example 4

[0051] 100mM didodecyl dimethyl ammonium bromide aqueous solution and 50mM tetradecanedioic acid aqueous solution were prepared respectively, and the above two aqueous solutions were mixed at a volume ratio of 1:1 at room temperature, and the pH was adjusted to 8. The ultrasonic power was adjusted to 10W, and the ultrasonic was performed for 5 minutes to obtain a non-covalently constructed oligomeric surfactant targeted deposition aid solution. 50mM cyhalofop-butyl herbicide original drug (99%) was added to the obtained non-covalently constructed oligomeric surfactant targeted deposition aid solution, and sprayed on rice and barnyard grass leaves. The droplets can rebound on the surface of the rice leaves and deposit on the surface of the barnyard grass leaves. Targeted deposition of the oligomeric surfactant solution on the barnyard grass leaves was achieved. The deposition efficiency of the droplets was tested, and the deposition efficiency of the droplets on the rice and barnyard grass leaves was 2.1% and 58.4%, respectively.

[0052] Example 5

[0053] 100mM aqueous solution of dihexadecyl dimethyl ammonium bromide and 50mM aqueous solution of tetradecanedioic acid were prepared respectively, and the above two aqueous solutions were mixed in a volume ratio of 1:1 at room temperature, and the pH was adjusted to 8. The ultrasonic power was adjusted to 10W, and the ultrasonic was performed for 5 minutes to obtain a non-covalently constructed oligomeric surfactant targeted deposition aid solution. 50mM cyhalofop-butyl herbicide original drug (99%) was added to the obtained non-covalently constructed oligomeric surfactant targeted deposition aid solution, and sprayed on rice and barnyard grass leaves. The droplets can rebound on the surface of the rice leaves and deposit on the surface of the barnyard grass leaves. Targeted deposition of the oligomeric surfactant solution on the barnyard grass leaves was achieved. The deposition efficiency of the droplets was tested, and the deposition efficiency of the droplets on the rice and barnyard grass leaves was 1.8% and 26.3%, respectively.

[0054] In the above embodiments, when the pH is adjusted to 9, 10, 11 or 12, after the mixture of the obtained oligomeric surfactant solution and the cyhalofop-butyl herbicide is sprayed, the droplets can still achieve targeted deposition on the leaves of barnyard grass.

[0055] Comparative Example 1

[0056] Prepare three times water with pH 8, add 50mM cyhalofop-butyl herbicide (99%), spray on rice and barnyard grass leaves, the droplets show obvious rebound on both rice and barnyard grass leaves. Test the deposition efficiency of the droplets, the deposition efficiency of the droplets on rice and barnyard grass leaves is 1.1% and 1.8% respectively.

[0057] Comparative Example 2

[0058] A 100 mM aqueous solution of ditetradecyl dimethyl ammonium bromide with a pH of 8 was prepared, 50 mM cyhalofop-butyl herbicide (99%) was added, and sprayed on rice and barnyard grass leaves. The droplets showed obvious rebound on both rice and barnyard grass leaves. The deposition efficiency of the droplets was tested, and the deposition efficiency of the droplets on rice and barnyard grass leaves was 1.6% and 2.8%, respectively.

[0059] Comparative Example 3

[0060] A 50 mM aqueous solution of tetradecanedioic acid with a pH of 8 was prepared, 50 mM cyhalofop-butyl herbicide (99%) was added, and sprayed on rice and barnyard grass leaves. The droplets showed obvious rebound on both rice and barnyard grass leaves. The deposition efficiency of the droplets was tested, and the deposition efficiency of the droplets on rice and barnyard grass leaves was 1.3% and 1.7%, respectively.

[0061] The above is an explanation of the embodiments of the present invention. However, the present invention is not limited to the above embodiments. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A non-covalently constructed oligomeric surfactant, characterized in that: The non-covalently constructed oligomeric surfactant is prepared from raw materials comprising: dialkyl dimethyl ammonium bromide and tetradecanedioic acid; The dialkyldimethylammonium bromide and tetradecanedioic acid form a dynamic oligomeric surfactant; The alkyl group is selected from an alkyl chain having 7 to 20 carbon atoms; The molar ratio of the dialkyl dimethyl ammonium bromide to tetradecanedioic acid is in the range of 1:1 to 4:1, the concentration of the dialkyl dimethyl ammonium bromide is in the range of 50 to 200 mM, and the concentration of the tetradecanedioic acid is in the range of 25 to 100 mM; The pH of the non-covalently constructed oligomeric surfactant is 7-13.

2. The non-covalently constructed oligomeric surfactant according to claim 1, characterized in that The dialkyldimethylammonium bromide is selected from one or more of dioctadecyldimethylammonium bromide, didecyldimethylammonium bromide, didodecyldimethylammonium bromide, ditetradecyldimethylammonium bromide and dihexadecyldimethylammonium bromide.

3. The non-covalently constructed oligomeric surfactant according to claim 1, characterized in that The non-covalently constructed oligomeric surfactant also includes solvent water.

4. The non-covalently constructed oligomeric surfactant according to claim 1, characterized in that The dialkyl dimethyl ammonium bromide is ditetradecyl dimethyl ammonium bromide; the molar ratio of the ditetradecyl dimethyl ammonium bromide to tetradecanedioic acid is 2:

1.

5. The non-covalently constructed oligomeric surfactant according to claim 1, characterized in that The concentration of the dialkyldimethylammonium bromide is 100 mM, and the concentration of the tetradecanedioic acid is 50 mM.

6. The method for preparing the non-covalently constructed oligomeric surfactant according to any one of claims 1 to 5, characterized in that: The preparation method comprises the following steps: mixing a dialkyl dimethyl ammonium bromide aqueous solution and a tetradecanedioic acid aqueous solution to obtain the non-covalently constructed oligomeric surfactant.

7. The method for preparing the non-covalently constructed oligomeric surfactant according to claim 6, characterized in that: The temperature of the mixed solution is 15 to 40° C., and / or the mixing time is 3 to 10 minutes.

8. Use of the non-covalently constructed oligomeric surfactant according to any one of claims 1 to 5 as a targeted deposition herbicide adjuvant.

9. The use according to claim 8, characterized in that: The targeted deposition herbicide adjuvant is a weed leaf targeted deposition herbicide adjuvant.

10. The use according to claim 8, characterized in that: The weeds are barnyard grass.

11. A herbicide, characterized in that: The herbicide contains the non-covalently constructed oligomeric surfactant according to any one of claims 1 to 5.

12. The herbicide according to claim 11, characterized in that The herbicide comprises the original drug and the non-covalently constructed oligomeric surfactant.

13. A herbicide adjuvant, characterized in that: The herbicide adjuvant contains the non-covalently constructed oligomeric surfactant according to any one of claims 1 to 5.

14. An aggregate, characterized in that The aggregate is formed by self-assembly of the non-covalently constructed oligomeric surfactant according to any one of claims 1 to 5.

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