Preparation Method and Application of Pesticide Nanocapsule Controlled Release Agent

Abstract

The present invention belongs to the field of pesticide formulations, and particularly relates to a preparation method and application of a pesticide nano-capsule controlled release agent, which comprises the following steps: adding a n-butanol solution containing a pesticide active ingredient into an aqueous solution containing a surfactant, stirring evenly to form an oil-in-water pesticide microemulsion; adding an aqueous tannic acid solution and an aqueous FeCl3 solution into the obtained product, so that Fe 3+ and the coordination polymer formed by the coordination of tannic acid are wrapped on the surface of the droplets of the oil-in-water pesticide microemulsion, and then through centrifugation, separation, washing and drying, the target product, the pesticide nano-capsule controlled release agent, is obtained. The present invention also discloses a method for controlling the release of pesticides in response to 8 stimuli, including acidity, alkalinity, glutathione, vitamin C, hydrogen peroxide, phosphate, phytic acid, sunlight (temperature). The present invention has the characteristics of simple preparation method, less use of raw materials, low cost, high pesticide loading rate, and easy degradation of nano-capsules.

Description

Technical Field

[0001] The present invention belongs to the field of pesticide formulations, and particularly relates to a preparation method and application of a pesticide nano-capsule controlled release agent. Background Art

[0002] Under the current arable land area, to feed the current global population of more than eight billion, food and agricultural products must increase in production and yield. The application of pesticides in agricultural production plays an irreplaceable role in increasing the yield of food and agricultural products, and the use of pesticides has made indelible contributions. Pesticides used for pest control can recover 30% of the total global agricultural product losses. However, under field application conditions, 90% of the pesticides are lost to the surrounding environment. After spray droplet drift, liquid medicine rolling off the crop leaves, rainwater scouring, and ultraviolet light degradation, the actual pesticide utilization rate by the target organisms is less than 0.1%. Due to the low actual pesticide utilization rate, pesticides are applied multiple times and in large quantities, causing ecological environmental pollution of air, soil, and water, and pesticide residues in agricultural products, ultimately posing a serious threat to human public health. The large amount of pesticide use, serious loss, and low effective utilization rate in China are a major problem faced by the agricultural field in China.

[0003] Compared with traditional pesticide formulations, pesticide micro-capsules have received increasing attention, and many preparation methods of pesticide micro-capsules have been developed. Pesticide micro-capsules use natural or synthetic polymer materials as wall materials to encapsulate pesticide active ingredients (i.e., core materials), forming micro-capsules with a particle size in the micron scale. Pesticide micro-capsules can control the slow release of pesticides, reduce the toxicity to non-target organisms, and reduce the degradation of pesticides caused by sunlight. Therefore, to a certain extent, pesticide micro-capsules improve the effective utilization rate of pesticides and reduce the ecological environmental pollution caused by pesticides. However, since the particle size of pesticide micro-capsules is in the micron scale, pesticide nano-capsules with smaller size and larger specific surface area can significantly increase the apparent dispersion degree of pesticides in water, improve the deposition and retention of pesticides on crop leaves, achieve targeted controlled release of pesticides, improve the bioavailability of pesticides, reduce the amount of pesticide use, and can achieve the purpose of reducing pesticide application and increasing efficiency. In 2019, the International Union of Pure and Applied Chemistry (IUPAC) first released the top ten emerging chemical technologies that will change the future world of the year, and nano-pesticides ranked first. Nano-pesticide formulations are expected to replace traditional pesticide formulations and solve the main challenges faced by traditional pesticide formulations, such as environmental pollution, bioaccumulation, and pest resistance. In recent years, the research and development of nano-pesticide formulations have received extensive attention globally.

[0004] Tannic acid (which has been approved by the US Food and Drug Administration) is a natural polyphenol widely present in the leaves, fruits, and barks of plants. It is composed of 5 peripheral gallic acid groups covalently linked to the central glucose through 5 esterified gallic acids. Under environmental conditions, tannic acid can rapidly form metal polyphenol polymers with many metal ions in water, and these coordination polymers are prone to adhering and depositing on various planar and particle surfaces. The reference titled "Using Coordination Assembly as the Microencapsulation Strategy to Promote the Efficacy and Environmental Safety of Pyraclostrobin" (Advanced Functional Materials 2017, 27, 1701841) reported an oil-in-water emulsion (with tetramethylbenzene as the oil phase) stabilized by the anionic surfactant calcium lignosulfonate (a multi-component polymer). First, Fe 3+ was added, and then tannic acid was added. After such 8 deposition cycles, pyraclostrobin microcapsules were prepared by the coordination assembly of Fe 3+ and tannic acid, with an average particle size of 9 micrometers and a wall thickness of 80 - 120 nm. The pesticide microcapsules prepared by the single deposition cycle of Fe 3+ and tannic acid ruptured after water evaporation, and pyraclostrobin crystals could be observed after 3 minutes; common emulsifiers and protective colloids did not obtain satisfactory emulsification effects, and non-ionic surfactants were not compatible with organic ligands; in addition, no pesticide release method and related data of the pyraclostrobin microcapsules were provided. Summary of the Invention

[0005] The present invention aims to overcome the deficiencies of the prior art and provides a preparation method and application of a pesticide nano-capsule controlled release agent with less raw material use, low cost, high pesticide loading, easy degradation of nano-capsules, and capable of promoting the reduction and efficiency increase of pesticides.

[0006] To solve the above technical problems, the present invention is realized as follows: A preparation method of a pesticide nano-capsule controlled release agent includes the following steps:

[0007] Step 1: Add a n-butanol solution containing a pesticide active ingredient to an aqueous solution containing a surfactant, and stir evenly to form an oil-in-water pesticide microemulsion;

[0008] Step 2: Add an aqueous tannic acid solution and an aqueous FeCl3 solution to the product obtained in Step 1 to make Fe 3+The coordination polymer formed by coordination assembly with tannic acid is wrapped on the surface of the droplets of the oil-in-water pesticide microemulsion, and then through centrifugation, separation, washing and drying, the target product, the pesticide nano-capsule controlled release agent, is obtained.

[0009] Preferably, in step 1, the surfactant is one or a mixture of two or more of the cationic surfactant cetyltrimethylammonium chloride (CTAC), the anionic surfactant sodium dodecyl sulfate (SDS), and the nonionic surfactant Tween-20.

[0010] Preferably, in step 1, the pesticide active ingredient is one or a mixture of two or more of tebuconazole, abamectin, emamectin benzoate, pyraclostrobin, difenoconazole, chlorpyrifos, and isoprothiolane.

[0011] Preferably, by mass percentage, the concentration of cetyltrimethylammonium chloride is 0.0004% - 1.5%; the concentration of sodium dodecyl sulfate is 0.093% - 0.28%; the concentration of Tween-20 is 0.32% - 0.96%.

[0012] Preferably, in step 1, the concentration of the pesticide active ingredient in n-butanol is 2 - 200 mg / mL.

[0013] Preferably, in step 1, the volume ratio of the aqueous phase to the oil phase of the n-butanol solution is 10 - 500:1.

[0014] Preferably, in step 2, the final concentration of the tannic acid aqueous solution is 0.05 - 0.5 mM; the final concentration of the FeCl3 aqueous solution is 0.05 - 1.5 mM.

[0015] Preferably, in step 2, the tannic acid aqueous solution and the FeCl3 aqueous solution are each added once or multiple times.

[0016] The application of the product obtained by the above method for preparing the pesticide nano-capsule controlled release agent in pesticide controlled release is to control pesticide release through environmental factors; the environmental factors are one or a combination of two or more of pH value (acidic, alkaline), glutathione (GSH), ascorbic acid (AA, vitamin C), hydrogen peroxide (H2O2), phosphate, phytic acid (PA, inositol hexaphosphate), and sunlight (temperature).

[0017] The present invention discloses a method for in-situ preparing a controlled-release pesticide nano-capsule using an oil-in-water (O / W) microemulsion (i.e., nanoemulsion) as a soft template. The water-insoluble pesticide active ingredient is dissolved in the oil phase (n-butyl alcohol). Conventional cationic surfactants, anionic surfactants, and non-ionic surfactants are used as emulsifiers to prepare the oil-in-water pesticide microemulsion. Iron 3+ and tannic acid are successively added to the oil-in-water pesticide microemulsion, and the two are "in-situ" coordinated and assembled at the interface of the microemulsion droplets to prepare the controlled-release pesticide nano-capsule. Iron 3+ and tannic acid can be added once each (i.e., the single deposition cycle mentioned above), or they can be added multiple times, regardless of the order of addition. In addition, the iron 3+ -tannic acid coordination polymer can absorb ultraviolet-visible-near-infrared light, which can not only prevent the pesticide in the microcapsule from degrading under ultraviolet light of sunlight, but also has good near-infrared light-to-heat conversion performance, and can realize the controlled release of pesticides through the photothermal effect of near-infrared light of sunlight. According to the characteristics of pests and diseases, the properties of the iron 3+ -tannic acid coordination polymer, the physiology of crops and the natural environment, the present invention also discloses 8 methods for stimulus-responsive controlled release of pesticides.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] 1. Generally, a microemulsion is a transparent or semi-transparent stable system spontaneously formed by four components of water, oil, emulsifier, and co-agent in an appropriate proportion, and its size is generally 50-200 nm. In the present invention, n-butyl alcohol not only serves as the oil phase for dissolving the pesticide active ingredient, but also functions as a co-agent. Without adding a co-agent other than the emulsifier, a stable oil-in-water microemulsion can be formed. The microemulsion is small in size and stable, and the pesticide nano-capsules prepared using it as a soft template are small in size and stable. The preparation of the controlled-release pesticide nano-capsule is simple, with less raw material usage and low cost.

[0020] 2. Conventional small molecule surfactants, including the cationic surfactant cetyltrimethylammonium chloride, the anionic surfactant sodium dodecylsulfonate, and the non-ionic surfactant Tween-20, are respectively used as emulsifiers to prepare the oil-in-water pesticide microemulsion. The types of applicable emulsifiers are more extensive.

[0021] 3. Iron 3+ and tannic acid are successively added to the oil-in-water pesticide microemulsion, and the two are "in-situ" coordinated and assembled at the interface of the microemulsion droplets to obtain the pesticide nano-capsules. Iron 3+ and tannic acid can form complete nano-capsules by adding once each. Of course, they can also be added multiple times to increase the wall thickness, regardless of the order of addition. Iron 3+It does not require multiple deposition cycles for tannic acid, has simple operation, uses less raw materials, and has low costs.

[0022] 4. The pesticide loading (mass percentage) in the pesticide nanocapsules is high, so that a low-concentration pesticide nanocapsule formulation can achieve the effect of preventing and controlling pests and diseases, reducing the production costs of users and also reducing the difficulties in aspects such as formulation and spraying of the formulation.

[0023] 5. Fe 3+ -tannic acid coordination polymer capsule wall can absorb ultraviolet-visible-near infrared light, which can not only prevent the ultraviolet light degradation of the core pesticide active ingredient of the nanocapsules by sunlight, but also has good near-infrared photothermal conversion performance, and can realize the controlled release of pesticides through the photothermal effect of the near-infrared light of sunlight.

[0024] 6. According to the characteristics of pests and diseases, the properties of Fe 3+ -tannic acid coordination polymer, the physiology of crops and the natural environment, the present invention discloses 8 kinds of stimulus-responsive pesticide controlled release methods including pH value (acidic, alkaline), glutathione (GSH), ascorbic acid (AA, vitamin C), hydrogen peroxide (H2O2), phosphate, phytic acid (PA, inositol hexaphosphate) and sunlight (temperature). It realizes the use of the pesticide controlled release of the pesticide nanocapsule controlled release agent, improves the prevention and control effect on target organisms, and reduces the toxicity to non-target organisms.

[0025] 7. Fe 3+ -tannic acid coordination polymer capsule wall has the advantages of non-toxicity, good biocompatibility, easy degradation, etc. Even if the nanocapsule controlled release agent enters the crop, it will eventually degrade, which not only prevents biological accumulation in the crop, but also finally prevents the potential biological accumulation risk in the human body. Description of the Drawings

[0026] Figure 1 It is the particle size distribution diagram of the dynamic light scattering (DLS) of the oil-in-water tebuconazole microemulsion of Example 1 and the prepared fungicide tebuconazole nanocapsule controlled release agent.

[0027] Figure 2 It is the (a) scanning electron microscope (SEM) and (b) transmission electron microscope (TEM) photos of the fungicide tebuconazole nanocapsule controlled release agent prepared in Example 1.

[0028] Figure 3 It is the electrophoretic potential (zeta) diagram of the oil-in-water tebuconazole microemulsion of Example 1 and the prepared fungicide tebuconazole nanocapsule controlled release agent.

[0029] Figure 4Thermogravimetric analysis (GTA) curves of the nano-capsule controlled release agent of the fungicide tebuconazole and the original tebuconazole drug prepared in Example 1.

[0030] Figure 5 a-i are SEM photos of the nano-capsule controlled release agents of the fungicide tebuconazole prepared in Examples 2-10 in sequence (Fe 3+ and tannic acid are added in the reverse order of Example 1), the nano-capsule controlled release agent of the fungicide tebuconazole (based on the microemulsion stabilized by sodium dodecyl sulfate), the nano-capsule controlled release agent of the fungicide tebuconazole (based on the microemulsion stabilized by Tween-20), the nano-capsule controlled release agent of the insecticide abamectin, the nano-capsule controlled release agent of the fungicide pyraclostrobin, the nano-capsule controlled release agent of the fungicide difenoconazole, the nano-capsule controlled release agent of the insecticide chlorpyrifos, the nano-capsule controlled release agent of the fungicide isoprothiolane, and the empty nano-capsules (without any pesticide active ingredients).

[0031] Figure 6 Ultraviolet-visible-near-infrared absorption spectrum, near-infrared photothermal effect, near-infrared photothermal conversion efficiency, and near-infrared photothermal stability of the nano-capsule controlled release agent of the fungicide tebuconazole prepared in Example 1.

[0032] Figure 7 a-i are the early release of pesticides of the nano-capsule controlled release agent of the fungicide tebuconazole prepared in Example 1 under non-stimulating conditions, and the pesticide controlled release curves of 8 kinds of stimuli responses including acidic, alkaline, glutathione (GSH), ascorbic acid (AA, vitamin C), hydrogen peroxide (H2O2), phosphate (PO4 3− ), phytic acid (PA), and temperature.

[0033] Figure 8 Abamectin anti-ultraviolet light degradation curve of the nano-capsule controlled release agent of the insecticide abamectin prepared in Example 1. Detailed implementation manners

[0034] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described below in conjunction with specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. These embodiments should be understood as only for explaining the present invention and not for limiting the protection scope of the present invention. After reading the content recorded in the present invention, all other embodiments obtained by making various changes or modifications to the present invention based on the technical solutions and embodiments of the present invention also fall within the protection scope of the claims of the present invention.

[0035] Example 1: Preparation of the nano-capsule controlled release agent of the fungicide tebuconazole

[0036] Quickly add 0.2 mL of a n-butanol solution (6 mg / mL) containing the active ingredient tebuconazole to 100 mL of an aqueous solution (0.030%, 0.936 mM) containing the cationic surfactant cetyltrimethylammonium chloride (CTAC), and stir vigorously for 30 min to obtain a clear and transparent oil-in-water (O / W) pesticide microemulsion. Then, add 0.6 mL of an aqueous tannic acid solution (20 mM) to the oil-in-water pesticide microemulsion, stir for 5 min, and then add 0.6 mL of an aqueous FeCl3 solution (20 mM) and stir for 5 min. Then, centrifuge (18,000 rpm) for separation, wash several times with water, and freeze-dry to obtain a tebuconazole nano-capsule controlled release agent.

[0037] Example 2: Preparation of a nano-capsule controlled release agent of the fungicide tebuconazole

[0038] Except that the addition order of FeCl3 and tannic acid is opposite to that in Example 1, that is, FeCl3 is added first and then tannic acid, and the rest of the preparation method is the same as that in Example 1.

[0039] Example 3: Preparation of a nano-capsule controlled release agent of the fungicide tebuconazole

[0040] Quickly add 1.88 - 3.59 mL of a n-butanol solution (10 mg / mL) containing the active ingredient tebuconazole to 97 mL of an aqueous solution (0.093% - 0.28%) containing the anionic surfactant sodium dodecyl sulfate (SDS), and stir vigorously for 30 min to obtain a clear and transparent oil-in-water (O / W) pesticide microemulsion. Then, add 0.3 mL of an aqueous FeCl3 solution (40 mM) and 0.3 mL of an aqueous tannic acid solution (40 mM) to the oil-in-water pesticide microemulsion, and the addition order of FeCl3 and tannic acid is not limited. Stir for 5 min each. Then, centrifuge (18,000 rpm) for separation, wash several times with water, and freeze-dry to obtain a tebuconazole nano-capsule controlled release agent.

[0041] Example 4: Preparation of a nano-capsule controlled release agent of the fungicide tebuconazole

[0042] Except that an aqueous solution (0.32% - 0.96%) of the non-ionic surfactant Tween-20 is used instead of the aqueous solution of sodium dodecyl sulfate in Example 3, the rest of the preparation method is the same as that in Example 3.

[0043] Example 5: Preparation of a nano-capsule controlled release agent of the insecticide abamectin

[0044] Except that the pesticide active ingredient abamectin is used instead of tebuconazole in Example 3, the preparation method of the abamectin nano-capsule controlled release agent is the same as that in Example 3.

[0045] Example 6: Preparation of Nano - capsule Controlled - Release Agent of Pyraclostrobin

[0046] Except for the pesticide active ingredient pyraclostrobin, replacing tebuconazole in Example 3, the preparation method of the pyraclostrobin controlled - release agent is the same as that in Example 3.

[0047] Example 7: Preparation of Nano - capsule Controlled - Release Agent of Difenoconazole

[0048] Except for the pesticide active ingredient difenoconazole, replacing tebuconazole in Example 3, the preparation method of the difenoconazole nano - capsule controlled - release agent is the same as that in Example 3.

[0049] Example 8: Preparation of Nano - capsule Controlled - Release Agent of Chlorpyrifos

[0050] Except for the pesticide active ingredient chlorpyrifos, replacing tebuconazole in Example 3, the preparation method of the chlorpyrifos nano - capsule controlled - release agent is the same as that in Example 3.

[0051] Example 9: Preparation of Nano - capsule Controlled - Release Agent of Isoprothiolane

[0052] Except for the pesticide active ingredient isoprothiolane, replacing tebuconazole in Example 3, the preparation method of the isoprothiolane nano - capsule controlled - release agent is the same as that in Example 3.

[0053] Example 10: Preparation of Empty Nano - capsules

[0054] Except for not adding any pesticide active ingredient, the preparation method of the empty nano - capsules is the same as that in Example 3.

[0055] Example 11: Pesticide Controlled Release of Pesticide Nano - capsule Controlled - Release Agent

[0056] Weigh multiple portions of 4 mg of the tebuconazole nano - capsule controlled - release agent prepared in Example 1, and disperse them separately in 1 mL of an aqueous solution containing ethanol (ethanol / water, 1:4, v / v) and 0.1% Tween - 80, encapsulate them in different dialysis bags (MWCO, 8000), and then place them separately in 9 mL of aqueous solutions containing ethanol (ethanol / water, 1:4, v / v) and 0.1% Tween - 80 with no stimulation, pH 5.0, pH 9.0, different concentrations of glutathione, different concentrations of vitamin C, different concentrations of H2O2, different concentrations of phosphate, different concentrations of phytic acid, and at different temperatures. Take 0.2 mL of the release sample solution at different intervals and add an equal volume of the corresponding fresh solution. Use high - performance liquid chromatography to determine the released pesticide active ingredient, and finally express the released pesticide by the cumulative release rate of the pesticide.

[0057] Figure 1Particle size distribution of the oil-in-water tebuconazole microemulsion of Example 1 and the prepared tebuconazole nanocapsule controlled release agent by dynamic light scattering. It can be seen that the hydrodynamic diameter of the droplets of the oil-in-water pesticide microemulsion (~96 nm), the hydrodynamic diameter of the pesticide nanocapsules prepared using the pesticide microemulsion as a soft template (~126 nm), and the (hydrodynamic) wall thickness of the nanocapsules (~15 nm). From the size of the hydrodynamic diameter of the droplets of the oil-in-water microemulsion, it is confirmed that the microemulsion prepared with n-butanol as the oil phase does not require the use of additives, indicating that the preparation method of the present invention is simple in operation, uses less raw materials, and has low costs.

[0058] Figure 2 Scanning electron microscope (a) and transmission electron microscope (b) photos of the tebuconazole nanocapsule controlled release agent prepared in Example 1. It can be seen that through tannic acid and Fe 3+ By a single deposition cycle with each addition once, the nearly spherical shape, size (~115 nm), and wall thickness (~9 nm) of the tebuconazole nanocapsules are prepared. The shape and size of the pesticide nanocapsules are relatively uniform, and the wall of the pesticide nanocapsules is complete (after solvent evaporation), indicating that the preparation method of the present invention is simple in operation, uses less raw materials, and has low costs.

[0059] Figure 3 Zeta potential of the oil-in-water tebuconazole microemulsion of Example 1 and the prepared tebuconazole nanocapsule controlled release agent. It can be seen that the surface of the droplets of the oil-in-water pesticide microemulsion stabilized by cetyltrimethylammonium chloride (CTAC) carries a positive charge (31.6 mV), and the surface of the prepared tebuconazole nanocapsules carries a negative charge (–33.5 mV), indicating that the Fe 3+ -tannic acid coordination polymer is encapsulated on the surface of the droplets of the microemulsion.

[0060] Figure 4 Thermogravimetric analysis curves of the tebuconazole nanocapsule controlled release agent prepared in Example 1 and the tebuconazole technical. Compared with the pesticide technical, the thermal stability of the pesticide encapsulated in the nanocapsules is improved. By high performance liquid chromatography determination, the drug loading of the pesticide in the pesticide nanocapsules reaches 87.6% (mass percentage), indicating that a low concentration of the pesticide nanocapsule formulation can achieve the effect of controlling pests and diseases, reducing the production costs of users, and also reducing the difficulty in aspects such as formulation and spraying of the formulation.

[0061] Figure 5 a to i are successively the tebuconazole nanocapsule controlled release agents (Fe 3+The addition order of tannic acid is opposite to that in Example 1), tebuconazole nano-capsule controlled release agent (based on microemulsion stabilized by sodium dodecyl sulfate), tebuconazole nano-capsule controlled release agent (based on microemulsion stabilized by Tween-20), abamectin nano-capsule controlled release agent, pyraclostrobin nano-capsule controlled release agent, difenoconazole nano-capsule controlled release agent, chlorpyrifos nano-capsule controlled release agent, isoprothiolane nano-capsule controlled release agent, empty nano-capsules (without any pesticidal active ingredient) scanning electron microscope photos. Obviously, it has nothing to do with the addition sequence of Fe 3+ and tannic acid, and stable pesticidal nano-capsule controlled release agents can be easily prepared. Besides the cationic surfactant cetyltrimethylammonium chloride as emulsifier, oil-in-water microemulsions respectively using the anionic surfactant sodium dodecyl sulfate and the non-ionic surfactant Tween-20 as emulsifiers can also prepare stable pesticidal nano-capsule controlled release agents. Besides the pesticidal active ingredient tebuconazole, water-insoluble pesticidal active ingredients such as abamectin, emamectin benzoate, pyraclostrobin, difenoconazole, chlorpyrifos, isoprothiolane, etc. can also be dissolved in the n-butanol oil phase to prepare stable pesticidal nano-capsule controlled release agents. When there is no any pesticidal active ingredient in the oil-in-water microemulsion, after the solvent evaporation of the prepared empty nano-capsules, the empty nano-capsules curl, but the capsule wall does not break, indicating that through tannic acid and Fe 3+ The stability of nano-capsules prepared by the single deposition cycle of adding each once, and the capsule wall remains intact without breaking.

[0062] Figure 6 For the UV-Vis-NIR absorption spectrum, near-infrared photothermal effect, near-infrared photothermal conversion efficiency, near-infrared photothermal stability of the tebuconazole nano-capsule controlled release agent prepared in Example 1. The Fe 3+ -tannic acid coordination polymer capsule wall of the tebuconazole nano-capsule controlled release agent has strong absorption in the UV-Vis-NIR region ( Figure 6 a). From the temperature increase ( 2 b) of the aqueous dispersion systems of tebuconazole nano-capsule controlled release agents with different concentrations under near-infrared light (808 nm, power density 1.00 W / cm Figure 6 ), and the temperature increase ( Figure 6 c) of the aqueous dispersion system of 1 mg / mL tebuconazole nano-capsule controlled release agent under 808 nm near-infrared light with different power densities, it is confirmed the near-infrared photothermal effect of the Fe 3+ -tannic acid coordination polymer capsule wall. From the temperature change curve ( 2 ) of the aqueous dispersion system of 1 mg / mL tebuconazole nano-capsule controlled release agent irradiated by 808 nm near-infrared light with a power density of 1.00 W / cm Figure 6d, e), the calculated near-infrared photothermal conversion efficiency of the pesticide nanocapsule controlled release agent is 27.4%. The temperature change curves of the 4 intermittent near-infrared irradiations of the water dispersion system of the tebuconazole nanocapsule controlled release agent illustrate the near-infrared photothermal stability of the pesticide nanocapsule controlled release agent ( Figure 6 f).

[0063] Figure 7 a - i are, in sequence, the early release of the pesticide from the tebuconazole nanocapsule controlled release agent prepared in Example 1 under no stimulation conditions, and the controlled release curves of the pesticide in response to 8 stimuli: acidic, alkaline, glutathione (GSH), ascorbic acid (AA, vitamin C), hydrogen peroxide (H2O2), phosphate (PO4 3− ), phytic acid (PA), and temperature (Example 11). In an aqueous solution containing ethanol (ethanol / water, 1:4, v / v) and 0.1% Tween-80, under no stimulation conditions, the pesticide nanocapsules show low early release of the pesticide. The cumulative release rate of the pesticide is about 12% at 24 h, 15% at 48 h, 20% at 96 h, and even less than 28% at 240 h cumulative release rate ( Figure 7 a). Under acidic (pH 5.0) conditions, the cumulative release rate of the pesticide at 240 h is 83% ( Figure 7 b), and under alkaline (pH 9.0) conditions, the cumulative release rate of the pesticide at 240 h is 86% ( Figure 7 c). In the presence of glutathione, the cumulative release rates of the pesticide at 240 h for 2 and 5 mM glutathione are 80% and 89% respectively ( Figure 7 d). In the presence of vitamin C, the cumulative release rates of the pesticide at 240 h for 0.1 and 0.2 mM vitamin C are 63% and 75% respectively ( Figure 7 e). In the presence of H2O2, the cumulative release rates of the pesticide at 240 h for 0.1 and 0.3 mM H2O2 are 56% and 70% respectively ( Figure 7 f). In the presence of phosphate, the cumulative release rates of the pesticide at 240 h for 2 and 5 mM phosphate are 71% and 79% respectively ( Figure 7 g). In the presence of phytic acid, the cumulative release rates of the pesticide at 240 h for 2 and 5 mM phytic acid are 81% and 92% respectively ( Figure 7 h). Under different temperature conditions (simulating the near-infrared photothermal effect of sunlight), the cumulative release rates of the pesticide at 240 h for 37, 43, and 51 °C are 54%, 70%, and 80% respectively ( Figure 7 i).

[0064] Figure 8 is the ultraviolet light degradation curve of abamectin of the abamectin nanocapsule controlled release agent prepared in Example 1. Fe 3+- The tannic acid coordination polymer capsule wall has strong absorption in the ultraviolet region, protecting the pesticidal active ingredient in the core from ultraviolet degradation by sunlight. When irradiated with 254 nm ultraviolet light for 48 h, 66% of the abamectin technical material undergoes photodegradation, while only 24% of the abamectin in the core of the abamectin nanocapsule controlled release agent undergoes ultraviolet degradation.

[0065] The above-described embodiments are only preferred embodiments of the present invention and are not intended to limit the present invention. It should be noted that various modifications and changes can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., including various microemulsions and other pesticidal active ingredients, made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A preparation method of a pesticide nano-capsule controlled release agent, characterized in that, It includes the following steps: Step 1: Add a n-butanol solution containing a pesticide active ingredient to an aqueous solution containing a surfactant, and stir evenly to form an oil-in-water pesticide microemulsion; the surfactant is one or a mixture of two or more of the cationic surfactant cetyltrimethylammonium chloride, the anionic surfactant sodium dodecylsulfonate, and the nonionic surfactant Tween-20; Step 2: Add an aqueous solution of tannic acid and an aqueous solution of FeCl3 to the product obtained in Step 1, so that Fe 3+ is coordinated and assembled with tannic acid to form a coordination polymer that coats the surface of the droplets of the oil-in-water pesticide microemulsion, and then through centrifugation, separation, washing and drying, the target product, the pesticide nano-capsule controlled release agent, is obtained.

2. The preparation method of the pesticide nano-capsule controlled release agent according to claim 1, characterized in that: In Step 1, the pesticide active ingredient is one or a mixture of two or more of tebuconazole, abamectin, emamectin benzoate, pyraclostrobin, difenoconazole, chlorpyrifos, and isoprothiolane.

3. The preparation method of the pesticide nano-capsule controlled release agent according to claim 2, characterized in that: In terms of mass percentage, the concentration of cetyltrimethylammonium chloride is 0.0004% to 1.5%; the concentration of sodium dodecylsulfonate is 0.093% to 0.28%; the concentration of Tween-20 is 0.32% to 0.96%.

4. The preparation method of the pesticide nano-capsule controlled release agent according to any one of claims 1 to 3, characterized in that: In Step 1, the concentration of the pesticide active ingredient in n-butanol is 2 to 200 mg / mL.

5. The preparation method of the pesticide nano-capsule controlled release agent according to claim 4, characterized in that: In Step 1, the volume ratio of the aqueous phase to the oil phase of the n-butanol solution is 10 to 500:

1.

6. The preparation method of the pesticide nano-capsule controlled release agent according to claim 5, characterized in that: In Step 2, the final concentration of the tannic acid aqueous solution is 0.05 to 0.5 mM; the final concentration of the FeCl3 aqueous solution is 0.05 to 1.5 mM.

7. The preparation method of the pesticide nano-capsule controlled release agent according to claim 6, characterized in that: In Step 2, the tannic acid aqueous solution and the FeCl3 aqueous solution are each added once or multiple times.

8. Use of the product obtained by the preparation method of the pesticide nano-capsule controlled release agent according to any one of claims 1 to 3 in pesticide controlled release, characterized in that: Control the pesticide release through environmental factors; the environmental factors are one or a combination of two or more of pH value, glutathione, vitamin C, hydrogen peroxide, phosphate, phytic acid, and sunlight.

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