Vegetable fat-methyl jasmonate nano composite material, preparation method thereof and application of nano composite material in improving freezing resistance of young pear fruits

Abstract

The invention discloses a grease-jasmonic acid methyl ester nano composite material, a preparation method thereof and an application of the grease-jasmonic acid methyl ester nano composite material in improving the freezing resistance of young pear fruits, and relates to the technical field of nano pesticides and young pear fruit freezing resistance. Comprising the following steps: 1, preparing an epoxy tea oil monomer from camellia oil; 2, dissolving an epoxy tea oil monomer and hydroxyethyl acrylate into ethanol, adding an initiator, and uniformly mixing to obtain a mixed solution; 3, carrying out freeze-thaw cycle, and carrying out polymerization reaction and purification in a nitrogen environment; and 4, adding jasmonic acid methyl ester, and then inducing self-assembly of the plant oil-based polymer to obtain the plant oil-based polymer. The method has the beneficial effects that the grease has good adhesion, and hydroxyl of hydroxyethyl ester and functional groups such as carboxyl on the surfaces of the young pears are bonded through hydrogen bonds, so that the adhesion of the nano-pesticide on the surfaces of the pears is improved, the rain wash resistance of methyl jasmonate on the surfaces of the young pears is improved, and the methyl jasmonate can be kept on the surfaces of the young pears for a long time; a large amount of hydroxyl also has an anti-freezing function, so that the anti-freezing capability of the young pears is greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of nano pesticides and antifreeze properties of young pear fruits, and in particular to an oil-methyl jasmonate nano composite material and a preparation method thereof and application thereof in improving the antifreeze properties of young pear fruits. Background Art

[0002] Pear is a temperate deciduous tree species. During dormancy, it can withstand low temperatures of -20℃ to -40℃. After dormancy is lifted, the tolerance of pear trees to low temperatures decreases rapidly. Young pear fruits are particularly sensitive to low temperature and frost weather. Pear trees often experience "late spring cold" during their young fruit period. The drastic drop in temperature causes irreversible damage to young fruits. In mild cases, it leads to a decrease in fruit setting rate and a decrease in the appearance and quality of the fruit. In severe cases, it can lead to a total loss of production and harvest, which has a serious impact on the yield of pears that year.

[0003] At present, most of the protective measures taken for pears are to strengthen external protection, such as building greenhouses, wrapping young fruits with film, building pear orchard shelterbelts, spraying chemical pesticides, growth regulators, or genetically regulating young fruits. However, external protection and measures to improve the resistance genes of pears themselves are difficult and costly; chemical pesticides are easy to remain, posing huge risks to the consumer environment and human health. Therefore, the development of green plant-based pesticides to protect young pear fruits from low temperature frost has both economic and ecological value.

[0004] Methyl jasmonate is a green plant-derived pesticide commonly used to protect young pear fruits from low-temperature frost. It can improve the frost resistance of young pear fruits while being environmentally friendly and harmless to human health. However, the poor dispersibility of methyl jasmonate in water, low adhesion to the surface of young pears, and easy degradation by ultraviolet light have greatly reduced the control efficiency of methyl jasmonate.

[0005] The use of nanotechnology to construct nanopesticides has received widespread attention in recent years. Nano-sizing pesticides can not only improve the dispersibility of pesticides in aqueous solutions, but also effectively improve the adhesion and UV resistance on plant surfaces, greatly improving the efficacy of pesticides. In addition, the special size effect of nanostructures and the easily controllable surface physical and chemical properties can be customized according to the properties of plant fruits and leaves.

[0006] The Chinese patent application document with publication number CN113854289A discloses a preparation method of a dual-loaded nanopesticide capsule containing dinotefuran and abamectin and a dual-loaded nanopesticide capsule prepared by the method, the preparation method comprising: step a: using dinotefuran and abamectin to prepare an inner water phase and an oil phase respectively, using an emulsifier to prepare an outer water phase, then dropping the inner water phase into the oil phase to obtain a W / O type emulsion, and then dropping the W / O type emulsion into the outer water phase to obtain a W / O / W type primary emulsion; step b: finely emulsifying the primary emulsion obtained in step a by high-pressure homogenization to obtain a fine emulsion; step c: stirring the fine emulsion obtained in step b to volatilize the organic solvent to obtain a dual-loaded nanopesticide capsule. The dual-loaded nanopesticide capsule prepared by the method has a nanometer-scale particle size, good particle dispersibility and leaf surface wetting performance, high effective utilization rate, and has a good control effect on pear borer. However, the nanopesticide in this patent has poor adhesion on the pear surface and weak resistance to UV degradation, so it needs further improvement. Summary of the invention

[0007] The technical problem to be solved by the present invention is how to solve the problems of poor adhesion of pesticides on the surface of young pears and weak resistance to ultraviolet degradation.

[0008] The present invention solves the above technical problems through the following technical means:

[0009] The first aspect of the present invention provides an amphiphilic oil macromolecular polymer having the structural formula The value range of m is 42 to 63, and the value range of n is 21 to 42. (“co” in the formula means copolymerization)

[0010] The second aspect of the present invention provides a method for preparing the above-mentioned amphiphilic lipid macromolecular polymer, comprising the following steps:

[0011] (1) Dissolve epoxy tea oil monomer (ECO) and hydroxyethyl acrylate in ethanol, add an initiator and mix well to obtain a mixed solution; the chemical formula of the epoxy tea oil monomer is as follows:

[0012]

[0013] (2) subjecting the mixed solution to freeze-thaw cycles, performing a polymerization reaction under a nitrogen environment, and purifying the reaction product by dialyzing to obtain a purified amphiphilic lipid polymer.

[0014] Preferably, in the step (1), the molar ratio of epoxy tea oil monomer (ECO), hydroxyethyl acrylate and initiator is 1:(1-3):0.011, and more preferably 1:1:0.011, 1:2:0.011, 1:3:0.011.

[0015] Preferably, the initiator in step (1) is one or more of azobisisobutyronitrile and azobisisoheptanenitrile.

[0016] Preferably, before using the hydroxyethyl acrylate in step (1), basic alumina is used to filter it to remove the polymerization inhibitor.

[0017] Preferably, the molecular weight cutoff of the dialysis bag used for dialysis in step (2) is 3500-4000, the dialysis time is 6-12 hours, and the water is replaced at least three times during the dialysis process.

[0018] The third aspect of the present invention proposes the use of the above-mentioned amphiphilic oil macromolecular polymer in increasing the adhesion of nanopesticides.

[0019] The fourth aspect of the present invention provides a method for preparing a plant oil-methyl jasmonate nanocomposite material, comprising the following steps: adding methyl jasmonate to the above-mentioned amphiphilic oil macromolecular polymer, and then adding deionized water to induce the amphiphilic plant oil-based macromolecule to self-assemble to form a nanoassembly.

[0020] (The hydrophilic part, hydroxyethyl acrylate, stabilizes the assembly on the outside, and the hydrophobic oil in the core of the nanoassembly can wrap methyl jasmonate through hydrophobic interaction to form a nanopesticide structure.)

[0021] The fifth aspect of the present invention provides a plant oil-methyl jasmonate nanocomposite material prepared by the above preparation method.

[0022] The sixth aspect of the present invention proposes the use of the above-mentioned plant oil-methyl jasmonate nanocomposite material in improving the frost resistance of young pear fruits.

[0023] Preferably, the method comprises the following steps: spraying the plant oil-methyl jasmonate nanocomposite material on the young fruits after the pear blossoms for three times, with an interval of 12 hours between each spraying.

[0024] The beneficial effects of the present invention are:

[0025] 1. The present invention utilizes the method of addition-fragmentation chain transfer polymerization to polymerize epoxy tea oil monomer and hydroxyethyl acrylate to prepare amphipathic grease polymer. With green and edible vegetable oil as raw material, the vegetable oil monomer containing double bonds is synthesized, and the polymerizability of double bonds is copolymerized with nontoxic and biocompatible hydroxyethyl acrylate, and the one-pot method is used to construct the amphipathic grease polymer in ethanol solution. Subsequently, a specific amount of methyl jasmonate is directly added to the solution after polymerization, and then deionized water is added to the solution to induce the amphipathic vegetable oil-based polymer to self-assemble to form a nano assembly, and the hydrophilic part hydroxyethyl ester stabilizes the assembly outside the assembly, and the hydrophobic grease can encapsulate methyl jasmonate through hydrophobic interaction in the nano assembly core to form a nano pesticide structure.

[0026] 2. The use of plant oils ensures the biodegradability and biocompatibility of the system. Moreover, because the oil has good adhesion, it can form hydrogen bonds with the hydroxyl groups of hydroxyethyl ester and the carboxyl groups on the surface of young pears, thereby increasing the adhesion of nanopesticides on the surface of pears, increasing the resistance of methyl jasmonate on the surface of young pears to rainwater erosion, and ensuring that methyl jasmonate can stay on the surface of young pears for a long time. At the same time, the large number of hydroxyl groups in the plant oil-based polymer also have an antifreeze function, which can greatly improve the antifreeze ability of young pears.

[0027] 3. In the practical application of improving the frost resistance of young pear fruits, a specific amount of methyl jasmonate is added to the amphiphilic grease macromolecule of the present invention, and deionized water is added to the solution to induce the amphiphilic plant oil-based macromolecule self-assembly to form a nano assembly. The hydrophilic functional group of the assembly allows it to adhere to the surface of young pear fruits, and the hydrophobic group can wrap up methyl jasmonate by hydrophobic interaction in the nano assembly core to form a nano pesticide structure. Under the influence of climate, site conditions, phenological period, etc., the use of vegetable oil increases the adhesion of nano pesticides on the surface of pears, increases the anti-rainwater scouring of methyl jasmonate on the surface of young pears, ensures that methyl jasmonate can stay on the surface of young pears for a long time, and a large amount of hydroxyls in the plant oil-based polymer also have the function of antifreeze, which can greatly improve the frost resistance of young pears. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of the synthesis route of the amphiphilic lipid polymer in Example 1 of the present invention.

[0029] Figure 2 This is the H NMR spectrum of the oil monomer in Example 1 of the present invention.

[0030] Figure 3 This is the H-NMR spectrum of the amphiphilic lipid polymer in Example 1 of the present invention.

[0031] Figure 4 This is the gel permeation chromatogram of the amphiphilic lipid polymer P (ECO-co-1HEA) in Example 1 of the present invention.

[0032] Figure 5 This is the gel permeation chromatogram of the amphiphilic lipid polymer P (ECO-co-2HEA) in Example 2 of the present invention.

[0033] Figure 6 This is the gel permeation chromatogram of the amphiphilic lipid polymer P (ECO-co-3HEA) in Example 3 of the present invention.

[0034] Figure 7 This is a Fourier infrared transform spectrum of the amphiphilic lipid polymer in Example 1 of the present invention.

[0035] Figure 8 This is the film-forming mechanism of the polymer vegetable oil-methyl jasmonate nanocomposite in Example 4 of the present invention.

[0036] Fig. 9 The scanning electron microscope images and fluorescence images of the amphiphilic lipid nanomaterials in Example 6 and Experiment 1 of the present invention are shown.

[0037] Fig.10 It is the fluorescence image of the amphiphilic lipid nanomaterial in Example 6 and Experiment 2 of the present invention.

[0038] Fig.11 The plant oil-methyl jasmonate nanocomposite in Test Example 1 of the present invention significantly improves the frost resistance of young pear fruits.

[0039] Fig.12 The plant oil-methyl jasmonate nanocomposite in Experimental Example 2 of the present invention significantly reduces the damage of young pear fruit cells caused by freezing. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] Unless otherwise specified, the test materials and reagents used in the following examples can be obtained from commercial sources.

[0042] If no specific techniques or conditions are specified in the examples, they can be carried out according to the techniques or conditions described in the literature in the art or according to the product instructions.

[0043] Example 1

[0044] This embodiment provides a method for synthesizing an amphiphilic lipid polymer, comprising the following steps:

[0045] References [Yan YY, Wu J, Wang Y, et al. Strong and UV-Responsive Plant Oil-Based Ethanol Aqueous Adhesives Fabricated Via Surfactant-free RAFT-Mediated Emulsion Polymerization [J]. Acs Sustainable Chemistry & Engineering, 2021, 9 (40): 13695-13702.] Epoxy tea oil monomer was obtained by multi-step synthesis using camellia oil as raw material. The chemical formula of the epoxy tea oil monomer is as follows:

[0046]

[0047] (2) Filter hydroxyethyl acrylate with alkaline alumina to remove the inhibitor. Then add 0.007 mol of epoxy tea oil monomer (ECO, 3 g) and 0.007 mol of hydroxyethyl acrylate (hydroxyethyl acrylate, 0.85 g) into an ampoule and dissolve in 18.0 mL of ethanol.

[0048] Then, azobisisobutyronitrile (AIBN, 0.079 mmol, 13 mg) was dissolved in ethanol and added to the ampoule bottle and mixed well, and the ampoule bottle was sealed;

[0049] (3) The mixed solution sealed in the ampoule was subjected to three freeze-thaw cycles, and then polymerized under nitrogen at 70°C for 8 h. The polymerization product was then dialyzed for 6 h using a dialysis bag with a molecular weight cutoff of 3500, and the water was replaced three times during the dialysis process to obtain a purified polymerization product, i.e., an amphiphilic lipid polymer. Figure 1 shown.

[0050] The preparation route of the amphiphilic lipid polymer in this embodiment is as follows Figure 1 As shown, during the synthesis process, the epoxy tea oil monomer of step (1) was subjected to nuclear magnetic characterization analysis to obtain a nuclear magnetic hydrogen spectrum as shown in Figure 2 As shown, it shows that the product (ECO) is successfully synthesized. The hydrogel polymer in step (2) is characterized by NMR and the NMR hydrogen spectrum is as follows: Figure 3 As shown, it shows that the polymer is successfully synthesized. The hydrogel polymer in step (2) is characterized by nuclear magnetic resonance and the nuclear magnetic hydrogen spectrum is as follows: Figure 3 As shown, it shows that the polymer was successfully synthesized. The prepared polymer P(ECO-co-1HEA) was subjected to gel permeation chromatography analysis, and the gel permeation chromatography was obtained as shown in FIG. Figure 4As shown, it can be seen that the peak molecular weight Mp of P(ECO-co-1HEA) is 9.7 kDa, the polydispersity index PDI is 1.71, and the molecular weight distribution is narrow. The product is then subjected to infrared analysis, and its Fourier transform infrared spectrum is as follows Figure 5 As shown, it can be seen that 1175cm -1 The characteristic peak of epoxy bond appears at 2920cm -1 The characteristic peak of the carbon-oxygen double bond in the ester bond appears at 3424 cm -1 The appearance of characteristic peaks of hydroxyl groups further proves the synthesis of the target polymer.

[0051] Example 2

[0052] This embodiment provides a method for synthesizing an amphiphilic lipid polymer, comprising the following steps:

[0053] (1) Hydroxyethyl acrylate was filtered with basic alumina to remove the inhibitor therein, and then 0.007 mol of epoxy tea oil monomer (ECO, 3 g) and 0.015 mol of hydroxyethyl acrylate (hydroxyethyl acrylate, 1.7 g) were added to an ampoule and dissolved in 32 mL of ethanol.

[0054] Azobisisobutyronitrile (AIBN, 0.079 mmol, 13 mg) was added into the ampoule and mixed well, and the ampoule was sealed.

[0055] (2) The mixed solution sealed in the ampoule was subjected to three freeze-thaw cycles, and then polymerized under a nitrogen environment at 75°C for 3 h. The polymerization product was then dialyzed with a dialysis bag with a molecular weight cutoff of 3500 for 6 to 12 h, and the water was replaced at least three times during the dialysis process, thereby obtaining a purified polymerization product, i.e., an amphiphilic lipid polymer material.

[0056] The prepared polymer amphiphilic oil polymer P (ECO-co-2HEA) was subjected to gel permeation chromatography analysis, and the gel permeation chromatogram was obtained as shown in the figure. It can be seen that the peak molecular weight Mp of the amphiphilic oil polymer material is 13kDa, the polydispersity index PDI is 1.71, and the molecular weight distribution is narrow.

[0057] Example 3

[0058] This embodiment provides a method for synthesizing an amphiphilic lipid polymer, which is different from Example 2 in that: ECO is 3 g (0.007 mol) and hydroxyethyl acrylate is 2.56 g (0.22 mol).

[0059] The prepared polymer amphiphilic oil polymer P (ECO-co-3HEA) was subjected to gel permeation chromatography analysis, and the gel permeation chromatogram was obtained as shown in the figure. It can be seen that the peak molecular weight Mp of the amphiphilic oil polymer material is 16kDa, the polydispersity index PDI is 1.96, and the molecular weight distribution is narrow.

[0060] Example 4

[0061] This embodiment provides a method for synthesizing a vegetable oil-methyl jasmonate nanocomposite material, comprising the following steps:

[0062] (1) The amphiphilic lipid polymers synthesized in Examples 1, 2, and 3 were dissolved in ethanol together with methyl jasmonate.

[0063] (2) Slowly add water to obtain the plant oil-methyl jasmonate nanocomposite material through self-assembly.

[0064] Example 5

[0065] This embodiment provides a method for synthesizing an amphiphilic lipid polymer, which differs from Embodiment 1 in that 0.0012 mmol of rhodamine colorant (rhodamine, 0.063 g) is added.

[0066] Example 6

[0067] This embodiment provides a method for synthesizing a fluorescent plant oil-methyl jasmonate nanocomposite material, comprising the following steps:

[0068] (1) The amphiphilic lipid polymer synthesized in Example 5 was dissolved in ethanol together with methyl jasmonate.

[0069] (2) Slowly add water to self-assemble to obtain fluorescent plant oil-methyl jasmonate nanocomposite materials.

[0070] Example 7

[0071] This embodiment provides an application of a plant oil-methyl jasmonate nanocomposite material in improving the frost resistance of young pear fruits and the adhesion of pesticides, comprising the following steps:

[0072] (1) The young fruits of 'Cui Guan' pear 15 days after full flowering were used as materials, and the reagents were sprayed with methyl jasmonate, three different proportions of plant oils and methyl jasmonate composite materials, and water spraying was used as a control. The young pear fruits were sprayed three times, with an interval of 12 hours between each treatment.

[0073] (2) Take branches with young fruits to the laboratory and subject the young fruits with different treatments to low temperature treatment (-3℃).

[0074] Test Example 1

[0075] According to the method of Example 5, the young fruit of the 'Cui Guan' pear 15 days after full bloom was used as the material, and the spraying agent was a fluorescent amphiphilic oil polymer material to spray the young pear fruit. Then, the branches with young fruit were taken to the laboratory for low temperature treatment (-3°C) of the young fruit with different treatments. The young pear fruit treated in Example 6 was observed under a fluorescence microscope and a scanning electron microscope. The results are as follows Fig. 9 Preliminary results show that the plant oil-methyl jasmonate nanocomposite has strong adhesion.

[0076] Test Example 2

[0077] According to the method of Example 5, the young fruit of the 'Cui Guan' pear 15 days after full bloom was used as the material, and the spraying reagents were water and the fluorescent amphiphilic oil polymer material. The pear young fruit was sprayed three times, and the interval between each treatment was 12 hours. Then, the branches with young fruit were taken to the laboratory for low temperature treatment (-3°C) of the young fruit with different treatments. The adhesion of the pear young fruit treated in Example 6 was observed after 12h, 24h, and 36h of growth. The results are as follows Fig.10 shown.

[0078] It can be seen that compared with the control group, the results show that the plant oil-methyl jasmonate nanocomposite still has strong adhesion after 36 hours.

[0079] Test Example 3

[0080] According to the method of Example 7, the young fruits of the 'Cui Guan' pear 15 days after full flowering were used as materials, and the control group was not treated at room temperature. The spraying reagents were water, methyl jasmonate, and a composite material of three kinds of plant oils with different hydrophilic and hydrophobic block ratios and methyl jasmonate. The pear young fruits were sprayed three times, and the interval between each treatment was 12 hours. Then, the branches with young fruits were taken to the laboratory for low temperature treatment (-3°C) of the young fruits with different treatments. The frost resistance of the pear young fruits treated in the control groups of Examples 4 and 7 was observed after 12h, 24h, and 36h of growth. The results are as follows Fig.11 As shown in A.

[0081] It can be seen that compared with the control group, preliminary results show that spraying of plant oil-methyl jasmonate nanocomplex significantly improves the frost resistance of young pear fruits.

[0082] Test Example 4

[0083] According to the method of Example 7, the young fruits of 'Cui Guan' pear 15 days after full flowering were used as materials, and the control group (RT) was not treated at room temperature. The spraying reagents were water, methyl jasmonate, and a composite material of three kinds of plant oils with different hydrophilic and hydrophobic block ratios and methyl jasmonate. The pear young fruits were sprayed three times, and the interval between each treatment was 12 hours. Then, the branches with young fruits were taken to the laboratory for low temperature treatment (-3°C) of the young fruits with different treatments. The frost resistance of the pear young fruits treated in the control groups of Examples 4 and 7 was observed after 12h, 24h, and 36h of growth. The results are as follows: Fig.11 As shown in B.

[0084] Under normal circumstances, the content of reactive oxygen in plants is in dynamic balance and will not harm plants. Under low temperature stress, the cell membrane system is damaged, the balance of reactive oxygen production and removal is disrupted, and excessive free radical content will affect the normal life activities of cell components, including superoxide anions (O2-) and hydrogen peroxide (H2O2). In order to maintain the redox homeostasis of plants, plants will activate the activity of protective enzymes to cope with low temperature stress. The protective enzyme system actively removes excessive reactive oxygen, but as the stress worsens, it exceeds the removal capacity of the protective enzyme system, and the plant will be injured and die. The protective enzyme system plays an important role in removing reactive oxygen free radicals and protecting the integrity of the membrane. For example, peroxidase (POD), superoxide dismutase (SOD) and catalase (CAT) are important protective enzymes in plants, which can remove the accumulation of reactive oxygen, reduce the harmful effects of low temperature stress on plants, stabilize the plant membrane system, and reduce the content of malondialdehyde (MDA) produced by membrane lipid peroxidation.

[0085] It can be seen that compared with the control group, the CAT, POD, and SOD contents of the plants treated with the plant oil-methyl jasmonate nanocomposite increased significantly, and the MDA, H2O2, and O2- contents decreased significantly. These results further prove that the spraying of the plant oil-methyl jasmonate nanocomposite significantly improves the frost resistance of young pear fruits.

[0086] Test Example 5

[0087] According to the method of Example 7, the young fruits of 'Cui Guan' pear 15 days after full flowering were used as materials, and the control group (RT) was not treated at room temperature. The spraying reagents were water, methyl jasmonate, and a composite material of three kinds of plant oils with different hydrophilic and hydrophobic block ratios and methyl jasmonate. The pear young fruits were sprayed three times, and the interval between each treatment was 12 hours. Then, the branches with young fruits were taken to the laboratory for low temperature treatment (-3°C) of the young fruits with different treatments. The pear young fruits treated in the control groups of Examples 4 and 7 were observed for cell damage after 12h, 24h, and 36h of growth. The results are as follows Fig.12 shown.

[0088] It can be seen that compared with the control group, preliminary results show that the degree of damage to pear young fruit cells was significantly reduced after spraying the plant oil-methyl jasmonate nanocomposite.

[0089] The implementation principle of the present invention is as follows: the present invention uses green and edible vegetable oil as a raw material to synthesize a vegetable oil monomer containing a double bond, utilizes the polymerizability of the double bond to copolymerize with hydroxyethyl acrylate which is non-toxic and has good biocompatibility, and constructs an amphiphilic oil polymer in an ethanol solution by a one-pot method. Subsequently, a specific amount of methyl jasmonate is directly added to the polymerized solution, and then deionized water is added to the solution to induce the amphiphilic vegetable oil-based polymer to self-assemble to form a nano-assembly, the hydrophilic part hydroxyethyl ester stabilizes the assembly outside the assembly, and the hydrophobic oil can encapsulate the methyl jasmonate in the core of the nano-assembly through hydrophobic interaction to form a nano-pesticide structure.

[0090] In the practical application of improving the frost resistance of young pear fruits, the amphiphilic oil polymer material of the present invention is wrapped on the surface of young pear fruits. Under the influence of climate and phenological conditions, the use of plant oils and fats ensures the biodegradability and biocompatibility of the system. Moreover, since the oils and fats have good adhesion, they can form hydrogen bonds with the hydroxyl groups of hydroxyethyl ester and the functional groups such as carboxyl groups on the surface of young pears, thereby increasing the adhesion of nanopesticides on the surface of pears and increasing the resistance of methyl jasmonate on the surface of young pears to rainwater scouring. While ensuring that methyl jasmonate can stay on the surface of young pears for a long time, a large number of hydroxyl groups in the plant oil-based polymer also have an antifreeze function, thereby greatly improving the frost resistance of young pears.

[0091] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An amphiphilic oil macromolecular polymer, characterized in that: Its structural formula is The value range of m is 42 to 63, and the value range of n is 21 to 42.

2. The method for preparing the amphiphilic oil macromolecular polymer according to claim 1, characterized in that: The following steps are involved: (1) Dissolve epoxy tea oil monomer and hydroxyethyl acrylate in ethanol, add initiator and mix well to obtain a mixed solution; the chemical formula of the epoxy tea oil monomer is as follows: (2) subjecting the mixed solution to freeze-thaw cycles, performing a polymerization reaction under a nitrogen environment, and purifying the reaction product by dialyzing to obtain a purified amphiphilic lipid polymer.

3. The preparation method according to claim 2, characterized in that: In the step (1), the molar ratio of the epoxy tea oil monomer, hydroxyethyl acrylate and initiator is 1:(1-3):0.

011.

4. The preparation method according to claim 2, characterized in that: In the step (2), the initiator is one or more of azobisisobutyronitrile and azobisisoheptanenitrile.

5. The preparation method according to claim 2, characterized in that: The molecular weight cutoff of the dialysis bag used for dialysis in step (2) is 3500-4000, the dialysis time is 6-12 hours, and the water is replaced at least three times during the dialysis process.

6. Use of the amphiphilic oil macromolecular polymer according to claim 1 in increasing the adhesion of nanopesticides.

7. A method for preparing a vegetable oil-methyl jasmonate nanocomposite material, characterized in that: The following steps are involved: The amphiphilic oil macromolecular polymer according to claim 1 is added with methyl jasmonate, and then deionized water is added to induce the amphiphilic plant oil-based macromolecular self-assembly to form a nano-assembly.

8. The vegetable oil-methyl jasmonate nanocomposite material obtained by the preparation method according to claim 7.

9. Use of the vegetable oil-methyl jasmonate nanocomposite material according to claim 8 in antifreeze of young pear fruits.

10. The use according to claim 9, characterized in that: The young fruits of pear were sprayed with plant oil-methyl jasmonate nanocomposite material three times after full flowering, with an interval of 12 hours between each spraying.

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