Preparation of modified polylactic acid drug-loaded material and application of modified polylactic acid drug-loaded material in pesticide preparation

Abstract

The invention relates to the technical field of pesticide preparations, and discloses preparation of a modified polylactic acid drug-loaded material and application of the modified polylactic acid drug-loaded material in the pesticide preparations, chlorpyrifos is used as a core material, the modified polylactic acid drug-loaded material is used as a wall material, and the chlorpyrifos-modified polylactic acid material is prepared. Mesoporous silicon and graphene oxide are utilized to improve the mechanical property of the material and the adsorption effect on a pesticide preparation, polylactic acid is grafted on the surface of lignin to improve the crosslinking degree, the mechanical property and the encapsulation effect of the drug-loaded material are further improved, the two components act together to achieve a good synergistic effect, all the raw materials are biodegradable materials, and the environment-friendly pesticide-loaded material is environmentally friendly. After use, secondary pollution to the environment is avoided, and great significance on development of efficient, environment-friendly and green agriculture is achieved. The modified polylactic acid drug-loaded material prepared by the invention has the advantages of being relatively good in environmental protection, and has relatively good encapsulation efficiency and comprehensive slow-release effect on a pesticide preparation.

Description

Technical Field

[0001] The invention relates to the technical field of pesticide preparations, and in particular to the preparation of a modified polylactic acid drug-carrying material and the application thereof in pesticide preparations. Background Art

[0002] my country is not only a country with a large population, but also a large agricultural country. The development of agricultural production is inseparable from the use of pesticides. Pesticides play a role that cannot be underestimated in preventing and controlling biological disasters, increasing crop yields, and promoting the sustained and stable growth of agricultural production. However, traditional pesticides have disadvantages such as solvent pollution, rapid loss of effective ingredients, and poor efficacy during use. Studies have shown that the use of drug carriers can significantly prolong the action time of pesticides, improve utilization efficiency, and thus reduce their impact on the ecological environment. Therefore, the research and development of drug-carrying materials is a hot topic for researchers.

[0003] Biodegradable materials can be divided into natural polymer materials and fully synthetic biodegradable polymer materials according to their sources. Natural polymer materials are widely used in the medical field due to their low toxicity, low pollution, and easy film formation. However, their mechanical strength is low, so their application is limited. Therefore, the development of low-cost drug-carrying materials with good mechanical properties has become a hot topic in the current research field of carrier materials.

[0004] Polylactic acid is non-toxic, non-irritating, has good plasticity, and good biocompatibility. It is widely used in the field of carrier materials and has become a highly-regarded drug controlled release carrier. However, the presence of a large number of hydrophobic group ester bonds in the molecular structure of polylactic acid leads to its poor hydrophilicity, which reduces its biocompatibility, and its strength often cannot meet the requirements. Therefore, it is necessary to modify it to prepare a modified polylactic acid drug-carrying material to meet the needs of modern pesticide formulations. Summary of the invention

[0005] 1. Technical issues to be resolved

[0006] In view of the shortcomings of the prior art, the present invention provides a preparation method of a modified polylactic acid drug-carrying material and its application in pesticide preparations. The prepared modified polylactic acid drug-carrying material has the advantages of good green environmental protection, and has a good encapsulation rate and comprehensive sustained-release effect for pesticide preparations.

[0007] (II) Technical solution

[0008] One of the purposes of the present invention is to provide a method for preparing a modified polylactic acid drug-carrying material, the preparation method comprising:

[0009] Add graphene oxide diol, mesoporous silicon modified lignin and L-lactide into a flask, stir and disperse, add 0.1-0.2 mol / L stannous octoate toluene solution therein, stir and mix evenly, heat to 65-75°C, remove toluene by vacuum distillation, fill the flask with nitrogen and evacuate the flask repeatedly three times, seal the flask, place it in a vacuum oven at 150-175°C for melt ring-opening polymerization for 3-6 hours, add dichloromethane for filtration after the reaction, wash with ethanol, and dry to obtain a modified polylactic acid drug-carrying material.

[0010] Preferably, the mass ratio of the graphene oxide-containing diol, the mesoporous silicon-modified lignin, and L-lactide is 0.1-0.5:0.1-0.5:1.

[0011] Preferably, the preparation method of the mesoporous silicon-modified lignin is as follows: add lignin to deionized water, adjust the pH to 10-11 with a 10% sodium hydroxide aqueous solution, heat to 85-95°C, add amino mesoporous silicon and a 37% formaldehyde aqueous solution, stir and react for 2-5 hours, and after the reaction is completed, wash with dilute hydrochloric acid and deionized water in turn, and dry to obtain mesoporous silicon-modified lignin.

[0012] Preferably, the mass ratio of the lignin to the amino-modified mesoporous silicon is 1:0.5-1.

[0013] Preferably, the preparation method of the graphene oxide-containing diol is:

[0014] (1) adding graphene oxide to deionized water, ultrasonically dispersing, adding sodium hydroxide and vinyl chloride thereto, stirring and dispersing, ultrasonically reacting for 2-4 hours, centrifugally washing with dilute hydrochloric acid, and drying to obtain olefinic graphene oxide;

[0015] (2) Under a nitrogen atmosphere, diethanolamine is added to an ethanol solvent, stirred and dispersed, and then olefinated graphene oxide is added thereto, the temperature is raised to 50-70° C., and the reaction is stirred for 12-24 hours. After the reaction is completed, the reaction is distilled under reduced pressure, washed with deionized water, and dried to obtain a graphene oxide-containing diol.

[0016] Preferably, in (1), the mass ratio of graphene oxide, sodium hydroxide and vinyl chloride is 1:40-55:25-50.

[0017] Preferably, in (2), the mass ratio of diethanolamine to olefinic graphene oxide is 0.5-1.5:1.

[0018] The second object of the present invention is to use the modified polylactic acid drug-carrying material in pesticide preparations, specifically, chlorpyrifos and polylactic acid are added to a dichloromethane solvent, wherein the mass ratio of chlorpyrifos to polylactic acid is 1:2-5, stirred and dissolved, and then a polyvinyl alcohol-gelatin aqueous solution with a mass fraction of 1.5% is added thereto, and a high-speed internal cut disperser is used for dispersion and emulsification for 2-4 minutes, and stirring is continued for 3-5 hours at a constant speed of 400r / min, and then filtered, washed with deionized water, and dried to obtain a chlorpyrifos-modified polylactic acid material.

[0019] (III) Beneficial technical effects

[0020] The invention uses lignin and amino mesoporous silicon and formaldehyde to react with Manniene to obtain mesoporous silicon modified lignin, uses graphene oxide and vinyl chloride to carry out substitution reaction to obtain olefinic graphene oxide, and then reacts with diethanolamine through Michael addition to obtain graphene oxide-containing diol, uses stannous octoate as a catalyst, uses graphene oxide-containing diol, mesoporous silicon modified lignin and L-lactide to carry out melt ring-opening polymerization to obtain modified polylactic acid drug-carrying material. Polyvinyl alcohol-gelatin aqueous solution is used as a continuous phase, chlorpyrifos and a dichloromethane solution of the modified polylactic acid drug-carrying material are used as an organic phase, and the mixture is evenly mixed, dispersed and emulsified, and dried to obtain chlorpyrifos-modified polylactic acid material.

[0021] The graphene and mesoporous silicon used in the present invention are inorganic materials, which show strong hydrophilic and oleophobic properties, which are not conducive to the dispersion of graphene and mesoporous silicon in a matrix material. Organic substances are introduced into the graphene and mesoporous silicon through reaction, so that the affinity of the graphene and mesoporous silicon with the organic phase is greatly enhanced. Introducing them into a modified polylactic acid material can enhance the mechanical properties and hydrophilic effect of the polylactic acid, and can not only increase the drug loading amount of the drug-carrying material, but also because the graphene and mesoporous silicon surfaces contain polar groups, they can generate van der Waals forces, hydrogen bonds and other forces with pesticide preparations such as chlorpyrifos, thereby increasing the encapsulation effect, delaying the release of the pesticide preparation, making it less likely to be lost, and improving the utilization rate.

[0022] In addition, the present invention utilizes the hydroxyl groups contained in lignin to undergo a melt ring-opening polymerization reaction with L-lactide, and grafts a polylactic acid structure on the surface of lignin, which can produce a huge cross-linked network structure and has a good encapsulation effect on pesticide preparations. When the concentration of the external pesticide preparation is low, the pesticide preparation can be slowly released into the environment, thereby improving the utilization rate of the pesticide preparation.

[0023] The present invention conducts melt ring-opening polymerization reaction of graphene oxide-containing diol, mesoporous silicon-modified lignin and L-lactide to obtain modified polylactic acid drug-carrying material, and polylactic acid is modified by graphene oxide-containing diol and mesoporous silicon-modified lignin to improve the molding stability and compatibility of the drug-carrying material, and the sustained release effect of graphene oxide, mesoporous silicon and lignin on pesticide preparation has good synergistic effect, and all raw materials are biodegradable materials, and no secondary pollution will be generated to the environment after use. It is of great significance to the development of efficient, environmentally friendly and green agriculture. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a scanning electron microscope picture of Example 3. It can be seen from the picture that the ball-forming effect is good, the spheres are regular and the surface is smooth, the protection effect on the core material is better, and the mechanical strength is also good. DETAILED DESCRIPTION

[0025] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only 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.

[0026] Preparation of amino mesoporous silica: Add 1 g of hexadecyltrimethylammonium bromide and 70 mL of ammonia water into deionized water, stir to dissolve, then add 5 g of ethyl orthosilicate and aminopropyltriethoxysilane, stir to react for 8 hours, after the reaction is completed, crystallize, filter, wash and dry to obtain amino mesoporous silica.

[0027] Preparation of graphene oxide: Add 3g of natural graphite powder to 140mL of concentrated sulfuric acid, stir for 1h in an ice-water bath, add 1.5g of sodium nitrate, stir and react for 10min, add 9g of potassium permanganate, continue stirring for 20min, heat to 90°C, react for 20min, add 500mL of deionized water, stir and react for 10min, add 30% hydrogen peroxide by mass, continue stirring and react for 2h, after the reaction is completed, wash with dilute hydrochloric acid and deionized water in turn, centrifuge, and dry to obtain graphene oxide.

[0028] Example 1

[0029] (1) 10 g of lignin was added to deionized water, and the pH was adjusted to 10 using a 10% sodium hydroxide aqueous solution. The temperature was raised to 95°C, and 6 g of amino-modified mesoporous silica and a 37% formaldehyde aqueous solution were added thereto. The mixture was stirred for 4 h. After the reaction was completed, the mixture was washed with dilute hydrochloric acid and deionized water in turn, and dried to obtain mesoporous silica-modified lignin.

[0030] (2) 1 g of graphene oxide was added to deionized water and ultrasonically dispersed. Then, 40 g of sodium hydroxide and 30 g of vinyl chloride were added thereto, stirred and dispersed, ultrasonically reacted for 3 h, washed by centrifugation with dilute hydrochloric acid, and dried to obtain olefinic graphene oxide.

[0031] (3) Under a nitrogen atmosphere, 5 g of diethanolamine was added to an ethanol solvent, and the mixture was stirred and dispersed. Then, 4 g of olefinic graphene oxide was added thereto, and the temperature was raised to 60° C., and the mixture was stirred and reacted for 24 h. After the reaction was completed, the mixture was distilled under reduced pressure, washed with deionized water, and dried to obtain a graphene oxide-containing diol.

[0032] (4) Add 1 g of graphene oxide-containing diol, 1 g of mesoporous silicon-modified lignin, and 10 g of L-lactide into a flask, stir and disperse, then add a 0.15 mol / L stannous octoate toluene solution thereto, stir and mix evenly, heat to 70°C, and vacuum distill to remove toluene. Fill the flask with nitrogen and evacuate the flask three times, seal the flask, and place it in a vacuum oven at 160°C for melt ring-opening polymerization for 5 hours. After the reaction is completed, add dichloromethane to filter, wash with ethanol, and dry to obtain a modified polylactic acid drug-carrying material.

[0033] (5) 2 g of chlorpyrifos and 4 g of modified polylactic acid drug-carrying material were added to a dichloromethane solvent and stirred to dissolve. Then, a polyvinyl alcohol-gelatin aqueous solution with a mass fraction of 1.5% was added thereto, and dispersed and emulsified for 3 min using a high-speed internal cut disperser. Stirring was continued for 3 h at a constant speed of 400 r / min, filtered, washed with deionized water, and dried to obtain a chlorpyrifos-modified polylactic acid material.

[0034] Example 2

[0035] (1) 10 g of lignin was added to deionized water, and the pH was adjusted to 11 using a 10% sodium hydroxide aqueous solution. The temperature was raised to 85°C, and 10 g of amino-modified mesoporous silica and a 37% formaldehyde aqueous solution were added thereto. The mixture was stirred for 5 h. After the reaction was completed, the mixture was washed with dilute hydrochloric acid and deionized water in turn, and dried to obtain mesoporous silica-modified lignin.

[0036] (2) 1 g of graphene oxide was added to deionized water and ultrasonically dispersed. Then, 55 g of sodium hydroxide and 30 g of vinyl chloride were added thereto, stirred and dispersed, ultrasonically reacted for 4 h, centrifuged and washed with dilute hydrochloric acid, and dried to obtain olefinic graphene oxide.

[0037] (3) Under a nitrogen atmosphere, 5 g of diethanolamine was added to an ethanol solvent, and the mixture was stirred and dispersed. Then, 4 g of olefinic graphene oxide was added thereto, and the temperature was raised to 70° C., and the mixture was stirred and reacted for 15 h. After the reaction was completed, the mixture was distilled under reduced pressure, washed with deionized water, and dried to obtain a graphene oxide-containing diol.

[0038] (4) Add 2 g of graphene oxide-containing diol, 2 g of mesoporous silicon-modified lignin, and 10 g of L-lactide into a flask, stir and disperse, then add a 0.2 mol / L stannous octoate toluene solution thereto, stir and mix evenly, raise the temperature to 65°C, and remove toluene by vacuum distillation. Fill the flask with nitrogen and evacuate the flask three times, seal the flask, and place it in a vacuum oven at 170°C for melt ring-opening polymerization for 5 hours. After the reaction is completed, add dichloromethane to filter, wash with ethanol, and dry to obtain a modified polylactic acid drug-carrying material.

[0039] (5) 2 g of chlorpyrifos and 6 g of modified polylactic acid drug-carrying material were added to a dichloromethane solvent and stirred to dissolve. Then, a polyvinyl alcohol-gelatin aqueous solution with a mass fraction of 1.5% was added thereto, and dispersed and emulsified for 4 min using a high-speed internal cut disperser. Stirring was continued for 4 h at a constant speed of 400 r / min, filtered, washed with deionized water, and dried to obtain a chlorpyrifos-modified polylactic acid material.

[0040] Example 3

[0041] (1) 10 g of lignin was added to deionized water, and the pH was adjusted to 10 using a 10% sodium hydroxide aqueous solution. The temperature was raised to 90°C, and 5 g of amino-modified mesoporous silica and a 37% formaldehyde aqueous solution were added thereto. The mixture was stirred for 2 h. After the reaction was completed, the mixture was washed with dilute hydrochloric acid and deionized water in turn, and dried to obtain mesoporous silica-modified lignin.

[0042] (2) 1 g of graphene oxide was added to deionized water and ultrasonically dispersed. Then, 40 g of sodium hydroxide and 50 g of vinyl chloride were added thereto, stirred and dispersed, ultrasonically reacted for 2 h, washed by centrifugation with dilute hydrochloric acid, and dried to obtain olefinic graphene oxide.

[0043] (3) Under a nitrogen atmosphere, 4 g of diethanolamine was added to an ethanol solvent, and the mixture was stirred and dispersed. Then, 4 g of olefinic graphene oxide was added thereto, and the temperature was raised to 70° C., and the mixture was stirred and reacted for 12 h. After the reaction was completed, the mixture was distilled under reduced pressure, washed with deionized water, and dried to obtain a graphene oxide-containing diol.

[0044] (4) Add 3 g of graphene oxide-containing diol, 3 g of mesoporous silicon-modified lignin, and 10 g of L-lactide into a flask, stir and disperse, then add a 0.1 mol / L stannous octoate toluene solution thereto, stir and mix evenly, heat to 70°C, and vacuum distill to remove toluene. Fill the flask with nitrogen and evacuate the flask three times, seal the flask, and place it in a vacuum oven at 175°C for melt ring-opening polymerization for 5 hours. After the reaction is completed, add dichloromethane to filter, wash with ethanol, and dry to obtain a modified polylactic acid drug-carrying material.

[0045] (5) 2 g of chlorpyrifos and 8 g of modified polylactic acid drug-carrying material were added to a dichloromethane solvent and stirred to dissolve. A polyvinyl alcohol-gelatin aqueous solution with a mass fraction of 1.5% was then added thereto. The mixture was dispersed and emulsified for 2 min using a high-speed internal cut disperser. The mixture was stirred for 5 h at a constant speed of 400 r / min, filtered, washed with deionized water, and dried to obtain a chlorpyrifos-modified polylactic acid material.

[0046] Example 4

[0047] (1) 10 g of lignin was added to deionized water, and the pH was adjusted to 11 using a 10% sodium hydroxide aqueous solution. The temperature was raised to 90°C, and 8 g of amino-modified mesoporous silica and a 37% formaldehyde aqueous solution were added thereto. The mixture was stirred for 4 h. After the reaction was completed, the mixture was washed with dilute hydrochloric acid and deionized water in turn, and dried to obtain mesoporous silica-modified lignin.

[0048] (2) 1 g of graphene oxide was added to deionized water and ultrasonically dispersed. Then, 45 g of sodium hydroxide and 25 g of vinyl chloride were added thereto, stirred and dispersed, ultrasonically reacted for 4 h, centrifuged and washed with dilute hydrochloric acid, and dried to obtain olefinic graphene oxide.

[0049] (3) Under a nitrogen atmosphere, 6 g of diethanolamine was added to an ethanol solvent, and the mixture was stirred and dispersed. Then, 4 g of olefinic graphene oxide was added thereto, and the temperature was raised to 50° C., and the mixture was stirred and reacted for 20 h. After the reaction was completed, the mixture was distilled under reduced pressure, washed with deionized water, and dried to obtain a graphene oxide-containing diol.

[0050] (4) 4 g of graphene oxide-containing diol, 4 g of mesoporous silicon-modified lignin, and 10 g of L-lactide were added to a flask and stirred to disperse. Then, a 0.2 mol / L stannous octoate toluene solution was added thereto and stirred to mix evenly. The temperature was raised to 65°C and toluene was removed by vacuum distillation. The flask was filled with nitrogen and vacuumed three times. The flask was sealed and placed in a vacuum oven at 175°C for melt ring-opening polymerization for 5 hours. After the reaction was completed, dichloromethane was added thereto for suction filtration, the mixture was washed with ethanol, and dried to obtain a modified polylactic acid drug-carrying material.

[0051] (5) 2 g of chlorpyrifos and 9 g of modified polylactic acid drug-carrying material were added to a dichloromethane solvent and stirred to dissolve. Then, a polyvinyl alcohol-gelatin aqueous solution with a mass fraction of 1.5% was added thereto, and dispersed and emulsified for 4 min using a high-speed internal cut disperser. Stirring was continued for 3 h at a constant speed of 400 r / min, filtered, washed with deionized water, and dried to obtain a chlorpyrifos-modified polylactic acid material.

[0052] Example 5

[0053] (1) 10 g of lignin was added to deionized water, and the pH was adjusted to 11 using a 10% sodium hydroxide aqueous solution. The temperature was raised to 95°C, and 6 g of amino-modified mesoporous silica and a 37% formaldehyde aqueous solution were added thereto. The mixture was stirred for 5 h. After the reaction was completed, the mixture was washed with dilute hydrochloric acid and deionized water in turn, and dried to obtain mesoporous silica-modified lignin.

[0054] (2) 1 g of graphene oxide was added to deionized water and ultrasonically dispersed. Then, 55 g of sodium hydroxide and 40 g of vinyl chloride were added thereto, stirred and dispersed, ultrasonically reacted for 3 h, centrifuged and washed with dilute hydrochloric acid, and dried to obtain olefinic graphene oxide.

[0055] (3) Under a nitrogen atmosphere, 2 g of diethanolamine was added to an ethanol solvent, and the mixture was stirred and dispersed. Then, 4 g of olefinic graphene oxide was added thereto, and the temperature was raised to 60° C., and the mixture was stirred and reacted for 24 h. After the reaction was completed, the mixture was distilled under reduced pressure, washed with deionized water, and dried to obtain a graphene oxide-containing diol.

[0056] (4) Add 5 g of graphene oxide-containing diol, 5 g of mesoporous silicon-modified lignin, and 10 g of L-lactide into a flask, stir and disperse, then add 0.15 mol / L stannous octoate toluene solution thereto, stir and mix evenly, heat to 70°C, and remove toluene by vacuum distillation. Fill the flask with nitrogen and evacuate the flask three times, seal the flask, and place it in a vacuum oven at 175°C for melt ring-opening polymerization for 5 hours. After the reaction is completed, add dichloromethane to filter, wash with ethanol, and dry to obtain a modified polylactic acid drug-carrying material.

[0057] (5) 2 g of chlorpyrifos and 10 g of modified polylactic acid drug-carrying material were added to a dichloromethane solvent and stirred to dissolve. Then, a polyvinyl alcohol-gelatin aqueous solution with a mass fraction of 1.5% was added thereto, and dispersed and emulsified for 3 min using a high-speed internal cut disperser. Stirring was continued for 4 h at a constant speed of 400 r / min, filtered, washed with deionized water, and dried to obtain a chlorpyrifos-modified polylactic acid material.

[0058] Comparative Example 1

[0059] The difference between this comparative example and Example 1 is that in step (5), polylactic acid is used instead of modified polylactic acid drug-carrying material.

[0060] HPLC was used to determine the drug loading and encapsulation efficiency of the microspheres. The detection conditions were: Amethyst C18-H column (4.6 mm × 250 mm), UV detector, column temperature of 25°C, flow rate of 1 mL / min, detection wavelength of 289 nm, injection volume of 20 μL, and mobile phase of 90% methanol-water solution.

[0061] Actual drug loading (%) = (mass of chlorpyrifos in microspheres / total mass of microspheres) × 100%;

[0062] Theoretical drug loading (%) = (actual mass of chlorpyrifos / actual mass of chlorpyrifos + actual mass of modified polylactic acid material) × 100%;

[0063] Encapsulation efficiency (%) = (actual drug loading / theoretical drug loading) × 100%.

[0064] Table 1:

[0065] Encapsulation rate (%) Example 1 86.7 Example 2 92.4 Example 3 95.5 Example 4 94.3 Example 5 92.0 Comparative Example 1 73.8

[0066] It can be seen from the table that the material prepared by the present invention has a good encapsulation rate for chlorpyrifos.

[0067] 1 g of chlorpyrifos-modified polylactic acid material was placed in a dialysis bag, immersed in 100 mL of deionized water, and shaken in a constant temperature water bath oscillator at 25°C. 2 mL of samples were taken at intervals of t days, and the concentration of chlorpyrifos was determined by HPLC. Then 2 mL of fresh distilled water was added to completely replace the soaking solution, and the cumulative release amount (%) was tested = (concentration of chlorpyrifos in the sustained-release medium at t days / concentration of chlorpyrifos after complete release) × 100%.

[0068] Table 2:

[0069]

[0070] It can be seen from the table that the modified polylactic acid drug-carrying material prepared by the present invention has a good sustained-release effect.

[0071] The technical solutions of the above embodiments are preferred implementation modes of the present invention. Several improvements and changes may be made without departing from the principles of the present invention. These improvements and changes should also be regarded as within the protection scope of the present invention.

Claims

1. A preparation method of a modified polylactic acid drug-carrying material, characterized in that: The preparation method is: Add graphene oxide diol, mesoporous silicon modified lignin and L-lactide into a flask, stir and disperse, add 0.1-0.2 mol / L stannous octoate toluene solution therein, stir and mix evenly, heat to 65-75°C, remove toluene by vacuum distillation, fill the flask with nitrogen and evacuate the flask repeatedly three times, seal the flask, place it in a vacuum oven at 150-175°C for melt ring-opening polymerization for 3-6 hours, add dichloromethane for filtration after the reaction, wash with ethanol, and dry to obtain a modified polylactic acid drug-carrying material.

2. The preparation of the modified polylactic acid drug-carrying material according to claim 1, characterized in that: The mass ratio of the graphene oxide-containing diol, the mesoporous silicon-modified lignin, and L-lactide is 0.1-0.5:0.1-0.5:

1.

3. The preparation of the modified polylactic acid drug-carrying material according to claim 1, characterized in that: The preparation method of the mesoporous silicon modified lignin is as follows: adding lignin to deionized water, adjusting the pH to 10-11 with a 10% sodium hydroxide aqueous solution, heating to 85-95° C., adding amino mesoporous silicon and a 37% by mass formaldehyde aqueous solution, stirring and reacting for 2-5 hours, and after the reaction is completed, washing with dilute hydrochloric acid and deionized water in turn, and drying to obtain the mesoporous silicon modified lignin.

4. The preparation of the modified polylactic acid drug-carrying material according to claim 3, characterized in that: The mass ratio of the lignin to the amino-modified mesoporous silicon is 1:0.5-1.

5. The preparation of the modified polylactic acid drug-carrying material according to claim 1, characterized in that: The preparation method of the graphene oxide-containing diol is: (1) adding graphene oxide to deionized water, ultrasonically dispersing, adding sodium hydroxide and vinyl chloride thereto, stirring and dispersing, ultrasonically reacting for 2-4 hours, centrifugally washing with dilute hydrochloric acid, and drying to obtain olefinic graphene oxide; (2) Under a nitrogen atmosphere, diethanolamine is added to an ethanol solvent, stirred and dispersed, and then olefinated graphene oxide is added thereto, the temperature is raised to 50-70° C., and the reaction is stirred for 12-24 hours. After the reaction is completed, the reaction is distilled under reduced pressure, washed with deionized water, and dried to obtain a graphene oxide-containing diol.

6. The preparation of the modified polylactic acid drug-carrying material according to claim 5, characterized in that: In the above (1), the mass ratio of graphene oxide, sodium hydroxide and vinyl chloride is 1:40-55:25-50.

7. The preparation of the modified polylactic acid drug-carrying material according to claim 5, characterized in that: In the above (2), the mass ratio of diethanolamine to olefinic graphene oxide is 0.5-1.5:

1.

8. An application of the modified polylactic acid drug-carrying material prepared by the preparation method according to claims 1 to 7 in pesticide preparations, characterized in that: Chlorpyrifos and polylactic acid are added to a dichloromethane solvent, wherein the mass ratio of chlorpyrifos to polylactic acid is 1:2-5, and the mixture is stirred and dissolved. Then, a polyvinyl alcohol-gelatin aqueous solution with a mass fraction of 1.5% is added thereto, and dispersion and emulsification are performed for 2-4 minutes using a high-speed internal cut disperser. Stirring is continued for 3-5 hours at a constant speed of 400 r / min, and the mixture is filtered, washed with deionized water, and dried to obtain a chlorpyrifos-modified polylactic acid material.

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