阅读说明：本技术 基于香草醇衍生物的聚酯、制备及用作农药缓释剂 (Polyester based on vanillyl alcohol derivatives, preparation and use as pesticide slow-release agents ) 是由 程正载 袁贝贝 孙欣 贾如艳 王欢 王林枫 蔡拴普 程俊鹏 杨迎澳 马里奥·高迪尔 于 2021-07-28 设计创作，主要内容包括：本发明公开了一种基于香草醇衍生物的聚酯、制备方法及用途,属于聚酯合成领域。以生物基香草醇和生物质来源的二元酸为起始原料,先对香草醇进行取代反应制得新型生物质二元醇,然后通过催化熔融酯化反应及催化熔融缩聚两步反应,制得了一种可生物降解的高分子量聚酯。本发明方法得到的聚酯的数均分子量M-(n)值为54500～75400 g/mol,其分子量分布M-(w)/M-(n)值为1.62～1.70。本发明具有聚酯收率高、分子量高和降解性能好等特点,主要用途是在农药微胶囊制备中起到载体作用,包裹农药活性分子,用于农药缓释剂的制备。(The invention discloses a polyester based on vanillyl alcohol derivatives, a preparation method and application thereof, belonging to the field of polyester synthesis. The method comprises the steps of taking bio-based vanillyl alcohol and binary acid derived from biomass as initial raw materials, firstly carrying out substitution reaction on the vanillyl alcohol to prepare novel biomass dihydric alcohol, and then carrying out two-step reaction of catalytic melt esterification reaction and catalytic melt polycondensation to prepare the biodegradable high-molecular-weight polyester. The number average molecular weight M of the polyesters obtained by the process of the invention n A molecular weight distribution M of 54500-75400 g/mol w /M n The value is 1.62 to 1.70. The invention has the characteristics of high polyester yield, high molecular weight, good degradation performance and the like, and is mainly used for playing a role of a carrier in the preparation of pesticide microcapsules, wrapping pesticide active molecules and preparing a pesticide slow-release agent.)

1. A polyester based on vanillyl alcohol derivatives, characterized by the structure as shown in formula I:

formula (II)

In the structural formula, n is 50-140.

2. A process for the preparation of a polyester based on vanillyl alcohol derivatives, according to claim 1, characterized in that: the method comprises the following three steps:

1) synthesis of diol monomer M: adding potassium carbonate with the amount of vanillyl alcohol and 0.10-0.20 time of the substance of vanillyl alcohol into a reaction container, adding N, N-dimethylformamide to dissolve the N, N-dimethylformamide, then dropwise adding 2-chloroethanol with the amount of 2 times of the substance of vanillyl alcohol, heating the reaction mixture to 85-90 ℃, continuously stirring and reacting for 2-4 hours, cooling to room temperature, then adding 0.10mol/L sodium hydroxide solution into the reaction mixture while stirring until the precipitate is not separated out any more, filtering, washing the filter cake with distilled water for 2-3 times, and drying in a 50 ℃ oven for 1-2 hours to obtain a dihydric alcohol monomer M with the structure as shown in the formula：

Formula (II)

2) And (3) synthesis of a crude polyester: the synthesized diol monomer M and the ethylene glycol bis (4-carboxyphenyl) ether with the CAS number of a diacid monomer from biomass being 3753-05-7 are used as reaction raw materials, nitrogen is introduced for protection, and the mixture is stirred at the temperature of 155-185 ℃ for esterification reaction for 2-4 hours under the action of a catalyst; and then stirring the mixture at a high vacuum pressure of less than 5-15 KPa and at a temperature of 210-240 ℃ to perform polycondensation reaction for 2-3 hours to obtain a polyester crude product.

3) And (3) purifying a crude polyester product: after cooling the polyester crude product under the protection of nitrogen, adding a proper amount of chloroform, soaking for 2-5 hours, and filtering; and dropwise adding the clear liquid into sufficient methanol to obtain a turbid system, centrifuging to obtain a precipitate, washing the precipitate for 3 times by using methanol, and filtering again to obtain a solid, and performing vacuum drying for 2-3 hours at the temperature of 60-70 ℃ to obtain the purified target polyester P.

3. A process for the preparation of a polyester based on vanillyl alcohol derivatives, according to claim 2, characterized in that: the ratio of the amount of the dihydric alcohol monomer M to the amount of the dibasic acid monomer ethylene glycol bis (4-carboxyphenyl) ether in the step 2) is 1 (1.0-1.5).

4. A process for the preparation of a polyester based on vanillyl alcohol derivatives, according to claim 2, characterized in that: the catalyst in the step 2) is one of tetra-n-butyl germanium, dicarboxyethyl germanium sesquioxide, monobutyl tin oxide and di-n-butyl tin dilaurate; the dosage of the catalyst is 0.10-0.50% of the mass of the dihydric alcohol monomer M.

5. The method for preparing polyester based on vanillyl alcohol derivatives according to claims 2 to 4, wherein the target polyester P is obtained by the following steps: the polyester is used as a capsule wall material, and the pesticide pyraclostrobin is used as a capsule core material to prepare a microcapsule wrapping the pesticide pyraclostrobin; the preparation method is characterized by comprising the following steps: fully mixing polyester P based on vanillyl alcohol derivatives and pyraclostrobin according to the mass ratio of 10 (1-3), and adding chloroform until the polyester P and the pyraclostrobin are completely dissolved; dripping the obtained mixed solution into a 2-8 wt% sodium dodecyl sulfate solution; and ultrasonically oscillating the obtained mixed system for 30 minutes, stirring for 2-4 hours at room temperature until the precipitate is not increased any more, filtering, washing the obtained precipitate with cold water, and freeze-drying to obtain the microcapsule wrapping the pesticide pyraclostrobin.

Technical Field

The invention belongs to the field of polymer chemistry, and relates to preparation and application of novel polyester. In particular to a bio-based diol monomer prepared by taking bio-based vanillyl alcohol as a raw material and carrying out substitution on hydroxyl on the bio-based vanillyl alcohol. The biomass-based degradable polyester with high molecular weight is prepared by taking bio-based dihydric alcohol and binary acid derived from biomass as reaction monomers and carrying out two-step reactions of catalytic esterification and catalytic polycondensation. The polyester is used as a capsule wall material, and the pesticide pyraclostrobin is used as a capsule core material to prepare the microcapsule wrapping the pesticide pyraclostrobin.

Background

Plastics are closely related to the development of human society, and polyester materials have been widely used in the fields of food packaging, plastic toys, engineering plastics, agriculture, and the like as one of important plastics. With the increasing concern about environmental pollution caused by fossil fuel-based polymers and the growing shortage of fossil resources, the development of chemicals, polymers and materials from biomass resources as raw materials has attracted great interest in both academic and industrial fields.

Due to the rapid growth of the world population, the demand for agricultural products is increasing. The pesticide can effectively prevent and control plant diseases and insect pests, can improve the yield of crops, and is widely applied in the agricultural field. However, conventional pesticide formulations have certain drawbacks such as high content of organic solvents, poor dispersibility, dust drift, high toxicity, and low targeting efficiency^[1]（[1] Huang B, Chen F, Shen Y, Qian K, Wang Y, Sun C. Advances in targeted pesticides with environmentally responsive controlled releaseby nanotechnology, Nanomaterials, 2018, 8: 1-18). On the basis, the slow release preparation can slowly release active ingredients, the release behavior is controlled by environmental factors and chemical condition factors, and the slow release preparation has the advantages of reducing the application times of pesticides, reducing the risk of non-target organisms, improving the lasting period of the pesticides and the like. The pesticide pyraclostrobin is a protective bactericide, has prevention and treatment effects, can be used for almost any crop, and has a good effect on a plurality of fungal diseases. However, the use of pyraclostrobin currently on the market has some problems. For example, the pesticide injury caused by the excess of the pyraclostrobin is the burning pesticide spot caused by the uneven distribution and the high local concentration of the pesticide after the pesticide is applied, most of the pesticide injuries are not necessarily caused by the use of the excess of the pesticide by farmers. Therefore, the development of the pesticide slow-release agent applicable to the pyraclostrobin is of great significance.

Various methods have been developed so far for the preparation of sustained-release pesticide formulations, and various sustained-release formulations such as suspension of pesticide microcapsules, sustained-release granules, hydrogel sustained-release formulations and the like have been registered and applied in the market at present. Dispersing the polymer in an organic phase by adopting a complex phase emulsion/volatilization technology, and dispersing the solution in a water phase by utilizing ultrasonic or mechanical stirring to prepare the microcapsule wrapping the active ingredient; wherein the polymer is used as a capsule wall material to coat the active ingredient, so as to improve the stability, solubility or permeability of the active ingredient, thereby realizing the controlled release of the active ingredient. The polymer material is generally concerned with good mechanical property and slow release rate, and the polymer material made of bio-based renewable chemicals also has the characteristics of environmental friendliness and degradability, does not generate degradation byproducts, is renewable in raw materials and relatively low in cost, and is proved to be a suitable packaging material. Estenoz topic group^[2]（[2]Busatto CA, Taverna ME, Lescano MR, Zaalzar C, Estenoze DA. Preparation and characterization of lignin microparticles in alkaline beads for atrazine controlled release. J Polymer Environ, 2019, 27: 2831-And adverse effects on the environment, however, the coating rate and drug loading are not ideal. At present, the actual application of the bio-based polymer material as the capsule wall material of the microcapsule is few, the capsule wall material in the market mainly depends on petroleum-based polymers, the biocompatibility and the biodegradability of the petroleum-based polymers are poor, and the non-biodegradable micro-plastic causes the pollution of oceans, water bodies and soil and brings threat to the environment and the life health of human beings.

Disclosure of Invention

Aiming at the problems, the technical problem to be solved by the invention is to provide a preparation method and application of a degradable polyester material based on vanillyl alcohol derivatives. The invention takes bio-based renewable chemical vanillyl alcohol as an initial raw material, further reacts to synthesize a dihydric alcohol monomer, and then reacts with a binary acid monomer derived from biomass through two steps of catalytic esterification and catalytic polycondensation to prepare the bio-based degradable polyester material. The polyester is used as a capsule wall material, and the pesticide pyraclostrobin is used as a capsule core material to prepare microcapsules wrapping the pesticide pyraclostrobin, and the microcapsules are used for preparing a pesticide slow release agent. The polyester has high molecular weight and excellent degradability; compared with the existing capsule wall material, the polyester has good coating rate and drug loading capacity, provides a new raw material with excellent performance for the production of a pesticide slow release agent, and has good development prospect in the field of pesticides.

In order to realize the purpose of the invention, the invention adopts the following technical scheme:

a polyester based on vanillyl alcohol derivatives, characterized by the structure as shown in formula I:

formula (II)

In the structural formula, n is 50-140.

The preparation method of the polyester based on the vanillyl alcohol derivative comprises the following three steps:

1) synthesis of novel diol monomer M: putting potassium carbonate with the amount of vanillyl alcohol and 0.10-0.20 time of the substance of vanillyl alcohol into a reaction container, adding N, N-Dimethylformamide (DMF) to dissolve the N, N-Dimethylformamide (DMF), then dropwise adding 2-chloroethanol with the amount of 2 times of the substance of vanillyl alcohol, heating the reaction mixture to 85-90 ℃, continuously stirring and reacting for 2-4 hours, cooling to room temperature, then adding 0.10mol/L sodium hydroxide solution into the reaction mixture while stirring until the precipitate is not separated out any more, filtering, washing the filter residue with distilled water for 2-3 times, and drying in an oven at 50 ℃ for 1-2 hours to obtain a dihydric alcohol monomer M with the structure as formula II:

formula II

2) And (3) synthesis of a crude polyester: the synthesized diol monomer M and the ethylene glycol bis (4-carboxyphenyl) ether with the CAS number of a diacid monomer from biomass being 3753-05-7 are used as reaction raw materials, nitrogen is introduced for protection, and the mixture is stirred at the temperature of 155-185 ℃ for esterification reaction for 2-4 hours under the action of a catalyst; and then stirring the mixture at a high vacuum pressure of less than 5-15 KPa and at a temperature of 210-240 ℃ to perform polycondensation reaction for 2-3 hours to obtain a polyester crude product.

3) And (3) purifying a crude polyester product: after cooling the polyester crude product under the protection of nitrogen, adding a proper amount of chloroform, soaking for 2-5 hours, and filtering; and dropwise adding the clear liquid into sufficient methanol to obtain a turbid system, centrifuging to obtain a precipitate, washing the precipitate for 3 times by using methanol, and filtering again to obtain a solid, and performing vacuum drying for 2-3 hours at the temperature of 60-70 ℃ to obtain the purified target polyester P.

More preferably, the ratio of the amounts of the glycol monomer M and the glycol bis (4-carboxyphenyl) ether in the step 2) is 1 (1.0-1.5).

More preferably, in the step 2), the catalyst is one of tetra-n-butyl germanium, dicarboxyethyl germanium trioxide, monobutyl tin oxide and di-n-butyl tin dilaurate; the dosage of the catalyst is 0.10-0.50% of the mass of the dihydric alcohol monomer M.

The main uses of a polyester P based on vanillyl alcohol derivatives described in the present invention are: the polyester is used as a capsule wall material, and the pesticide pyraclostrobin is used as a capsule core material to prepare a microcapsule wrapping the pesticide pyraclostrobin; the preparation method is characterized by comprising the following steps: fully mixing polyester P based on vanillyl alcohol derivatives and pyraclostrobin according to the mass ratio of 10 (1-3), and adding chloroform until the polyester P and the pyraclostrobin are completely dissolved; dripping the obtained mixed solution into a 2-8 wt% sodium dodecyl sulfate solution; and ultrasonically oscillating the obtained mixed system for 30 minutes, stirring for 2-4 hours at room temperature until the precipitate is not increased any more, filtering, washing the obtained precipitate with cold water, and freeze-drying to obtain the microcapsule wrapping the pesticide pyraclostrobin.

Advantageous effects

1. The polymer is prepared by using bio-based renewable chemicals such as vanillyl alcohol and dibasic acid derived from biomass as starting raw materials, petroleum-based polymers are replaced, the problem of shortage of petroleum resources in the future can be partially relieved, the implementation of national carbon emission reduction and carbon neutralization national policy is facilitated, and the biomass is used as a renewable resource in the nature and has the advantages of richness, diversity, low cost and the like.

2. The synthesized bio-based polymer material is characterized in that: the macromolecular polyester structure contains abundant carbon-oxygen bonds, and the chemical structure is difficult to economically prepare from fossil fuels and endows the polymer with functionality, controllability and biodegradability. The bio-based polyester is applied to the field of pesticides, can be degraded into small molecules such as water and carbon dioxide under the action of microorganisms in natural environments such as field farms and the like, and participates in the circulation of an ecological system.

3. The synthesized bio-based polymer material is used for preparing pesticide microcapsules while keeping non-toxicity, low cost and biodegradability, and can remarkably reduce the dosage of pesticides and reduce the damage to the environment. The prepared pesticide microcapsule can be buried in soil together with seeds buried underground, can sterilize and kill pests for a long time, protects the roots of crops from being damaged by plant diseases and insect pests during the seed development process of the crops and after the crops grow, and realizes the long-term utilization of pesticides.

Detailed description of the preferred embodiments

The present invention will be further illustrated by the following examples, but the present invention is not limited to these examples. The raw materials in the invention are all conventional and commercially available. In order to clearly understand the objects, technical solutions and advantages of the present invention, the present invention will be further described in detail with reference to the following embodiments. The specific examples described herein refer to specific data only to illustrate the invention and are not meant to limit the invention.

The structure of the monomers and polyesters prepared in the examples was determined: the determination is carried out by adopting a Bruker Avance DMX600 nuclear magnetic resonance instrument of Germany Bruker spectral instruments and a VERTEX70 Fourier transform infrared spectrometer of Germany Bruker spectral instruments;

testing of microcapsules in the examples: the coating rate and the drug loading capacity are tested by an ultraviolet-visible spectrophotometer produced by Shimadzu experimental equipment company Limited; the particle size distribution and the polydispersity index were measured using a malvern laser particle sizer manufactured by malvern instruments ltd, united kingdom;

determination of the molecular weights and their distribution of the polyesters in the examples: measuring with Waters 2412 type gel permeation chromatograph with tetrahydrofuran as mobile phase;

the results were averaged over 3 test specimens each.

Yield =100% x actual amount of target product/theoretical amount of target product produced.

Example 1

Synthesis of diol monomer M: 7.708g (0.05 mol) of vanillyl alcohol and 1.382g (0.01 mol) of potassium carbonate were put in a reaction vessel, 100mL of N, N-Dimethylformamide (DMF) was added and dissolved, 8.052g (0.10 mol) of 2-chloroethanol was added dropwise thereto, and the reaction was stirred at 85 ℃ for 4 hours, and after completion of the reaction, the reaction was cooled to room temperature. Then adding 50mL (0.10 mol/L) of sodium hydroxide solution while stirring to separate out white insoluble substances, filtering, washing the filter cake twice with 200mL of distilled water, and drying the filter cake in an oven at 50 ℃ for 1-2 hours to obtain a diol monomer M, namelyThe yield thereof was found to be 78.54%.

Example 2

2.421g (0.01 mol) of dihydric alcohol monomer M, 3.023g (0.010 mol) of dibasic acid monomer ethylene glycol bis (4-carboxyphenyl) ether and 0.006g of tetra-n-butyl germanium are sequentially added into the dried single-neck flask, nitrogen is introduced for protection, and the mixture is stirred at 170 ℃ for esterification reaction for 4 hours; and then stirring the mixture at a high vacuum pressure of less than 5-15 KPa at 240 ℃ to perform polycondensation reaction for 3 hours to obtain a polyester crude product. After the polyester crude product is cooled under the protection of nitrogen, adding 50mL of chloroform, soaking for 3 hours, and filtering; adding the clear solution dropwise into sufficient methanol to obtain turbid system, centrifuging to obtain precipitate, washing the precipitate with methanol for 3 times, filtering again to obtain solid, and vacuum drying at 70 deg.C for 2 hr to obtain 4.841g of polyester P₁The number-average molecular weight was 54500g/mol, and the yield was 86.73%.

Polyester P₁The method for preparing the microcapsule wrapping the pesticide pyraclostrobin comprises the following steps: 3 parts by mass of a polyester P₁And 0.5 part by mass of pyraclostrobin are fully mixed, and chloroform is added until the mixture is completely dissolved; dropping the obtained mixed solution into 50 parts by mass of a 8wt% sodium dodecyl sulfate solution; ultrasonically oscillating the obtained mixed system for 30 minutes, stirring for 2 hours at room temperature until the precipitate is not increased any more, filtering, washing the obtained precipitate with cold water for 3 times, and freeze-drying to obtain the microcapsule NP wrapping the pesticide pyraclostrobin₁。

Example 3

2.421g (0.01 mol) of dihydric alcohol monomer M, 3.325g (0.011 mol) of dibasic acid monomer ethylene glycol bis (4-carboxyphenyl) ether and 0.006g of dicarboxyethyl germanium sesquioxide are sequentially added into the dried single-neck flask, nitrogen is introduced for protection, and the mixture is stirred at 150 ℃ for esterification reaction for 3 hours; and then stirring the mixture at a high vacuum pressure of less than 5-15 KPa at 220 ℃ for carrying out polycondensation reaction for 3 hours to obtain a polyester crude product. After the polyester crude product is cooled under the protection of nitrogen, adding 50mL of chloroform, soaking for 2 hours and then filtering; adding the clear solution dropwise into sufficient methanol to obtain turbid system, centrifuging to obtain precipitate, washing with methanolThe precipitate was washed 3 times and the solid obtained after filtration was dried in vacuo at 65 ℃ for 3 hours to give 4.651g of polyester P₂The number-average molecular weight was 56800g/mol, and the yield was 88.52%.

Polyester P₂The method for preparing the microcapsule wrapping the pesticide pyraclostrobin comprises the following steps: 3 parts by mass of a polyester P₂And 0.5 part by mass of pyraclostrobin are fully mixed, and chloroform is added until the mixture is completely dissolved; dropping the obtained mixed solution into 50 parts by mass of a 4wt% sodium dodecyl sulfate solution; ultrasonically oscillating the obtained mixed system for 30 minutes, stirring for 3 hours at room temperature until the precipitate is not increased any more, filtering, washing the obtained precipitate for 3 times by using cold water, and freeze-drying to prepare the microcapsule NP wrapping the pesticide pyraclostrobin₂。

Example 4

2.421g (0.01 mol) of dihydric alcohol monomer M, 3.627g (0.012 mol) of dibasic acid monomer ethylene glycol bis (4-carboxyphenyl) ether and 0.010g of monobutyl tin oxide are sequentially added into the dried single-neck flask, nitrogen is introduced for protection, and the mixture is stirred at 160 ℃ for esterification reaction for 4 hours; and then stirring the mixture at a high vacuum pressure of less than 5-15 KPa at 230 ℃ for carrying out polycondensation reaction for 3 hours to obtain a polyester crude product. After the polyester crude product is cooled under the protection of nitrogen, adding 50mL of chloroform, soaking for 3 hours, and filtering; adding the clear solution dropwise into sufficient methanol to obtain turbid system, centrifuging to obtain precipitate, washing the precipitate with methanol for 3 times, filtering again to obtain solid, and vacuum drying at 65 deg.C for 2 hr to obtain 4.852g of polyester P₃The number-average molecular weight was 62100g/mol, and the yield was 87.16%.

Polyester P₃The method for preparing the microcapsule wrapping the pesticide pyraclostrobin comprises the following steps: 3 parts by mass of a polyester P₃Fully mixing with 0.6 part by mass of pyraclostrobin, and adding chloroform until the mixture is completely dissolved; dropping the obtained mixed solution into 50 parts by mass of a 2wt% sodium dodecyl sulfate solution; ultrasonically oscillating the obtained mixed system for 30 minutes, stirring for 4 hours at room temperature until the precipitate is not increased any more, filtering, washing the obtained precipitate with cold water for 3 times, and freeze-drying to obtain the microcapsule NP wrapping the pesticide pyraclostrobin₃。

Example 5

2.421g (0.01 mol) of dihydric alcohol monomer M, 3.023g (0.010 mol) of dibasic acid monomer ethylene glycol bis (4-carboxyphenyl) ether and 0.012g of di-n-butyltin dilaurate are sequentially added into a dried single-neck flask, nitrogen is introduced for protection, and the mixture is stirred at 180 ℃ for esterification reaction for 2 hours; and then stirring the mixture at a high vacuum pressure of less than 5-15 KPa at 230 ℃ for carrying out polycondensation reaction for 3 hours to obtain a polyester crude product. After the polyester crude product is cooled under the protection of nitrogen, adding 50mL of chloroform, soaking for 4 hours, and filtering; adding the clear solution dropwise into sufficient methanol to obtain turbid system, centrifuging to obtain precipitate, washing the precipitate with methanol for 3 times, filtering again to obtain solid, and vacuum drying at 70 deg.C for 2 hr to obtain 4.732g of polyester P₄The number-average molecular weight was 65400g/mol, and the yield was 89.74%.

Polyester P₄The method for preparing the microcapsule wrapping the pesticide pyraclostrobin comprises the following steps: 3 parts by mass of a polyester P₄Fully mixing with 0.6 part by mass of pyraclostrobin, and adding chloroform until the mixture is completely dissolved; dropping the obtained mixed solution into 50 parts by mass of a 4wt% sodium dodecyl sulfate solution; ultrasonically oscillating the obtained mixed system for 30 minutes, stirring for 4 hours at room temperature until the precipitate is not increased any more, filtering, washing the obtained precipitate with cold water for 3 times, and freeze-drying to obtain the microcapsule NP wrapping the pesticide pyraclostrobin₄。

Example 6

2.421g (0.01 mol) of dihydric alcohol monomer M, 3.325g (0.011 mol) of dibasic acid monomer ethylene glycol bis (4-carboxyphenyl) ether and 0.012g of monobutyl tin oxide are sequentially added into the dried single-neck flask, nitrogen is introduced for protection, and the mixture is stirred at 170 ℃ for esterification reaction for 3 hours; and then stirring the mixture at a high vacuum pressure of less than 5-15 KPa at 240 ℃ to perform polycondensation reaction for 3 hours to obtain a polyester crude product. After the polyester crude product is cooled under the protection of nitrogen, adding 50mL of chloroform, soaking for 3 hours, and filtering; adding the clear solution dropwise into sufficient methanol to obtain turbid system, centrifuging to obtain precipitate, washing the precipitate with methanol for 3 times, filtering again to obtain solid, and vacuum drying at 65 deg.C for 2 hr to obtain 5.221g of polyester P₅The number average molecular weight is 68100g/mol,the yield thereof was found to be 88.65%.

Polyester P₅The method for preparing the microcapsule wrapping the pesticide pyraclostrobin comprises the following steps: 3 parts by mass of a polyester P₅Fully mixing with 0.8 part by mass of pyraclostrobin, and adding chloroform until the mixture is completely dissolved; dropping the obtained mixed solution into 50 parts by mass of a 8wt% sodium dodecyl sulfate solution; ultrasonically oscillating the obtained mixed system for 30 minutes, stirring for 2 hours at room temperature until the precipitate is not increased any more, filtering, washing the obtained precipitate with cold water for 3 times, and freeze-drying to obtain the microcapsule NP wrapping the pesticide pyraclostrobin₅。

Example 7

2.421g (0.01 mol) of dihydric alcohol monomer M, 3.627g (0.012 mol) of dibasic acid monomer ethylene glycol bis (4-carboxyphenyl) ether and 0.008g of tetra-n-butyl germanium are sequentially added into a dried single-neck flask, nitrogen is introduced for protection, and the mixture is stirred at 160 ℃ for esterification reaction for 4 hours; and then stirring the mixture at a high vacuum pressure of less than 5-15 KPa at 210 ℃ for carrying out polycondensation reaction for 3 hours to obtain a polyester crude product. After the polyester crude product is cooled under the protection of nitrogen, adding 50mL of chloroform, soaking for 3 hours, and filtering; adding the clear solution dropwise into sufficient methanol to obtain turbid system, centrifuging to obtain precipitate, washing the precipitate with methanol for 3 times, filtering again to obtain solid, and vacuum drying at 70 deg.C for 2 hr to obtain 5.368g of polyester P₆The number-average molecular weight was 75400g/mol, and the yield was 89.49%.

Polyester P₆The method for preparing the microcapsule wrapping the pesticide pyraclostrobin comprises the following steps: 3 parts by mass of a polyester P₆Fully mixing with 0.8 part by mass of pyraclostrobin, and adding chloroform until the mixture is completely dissolved; dropping the obtained mixed solution into 50 parts by mass of a 2wt% sodium dodecyl sulfate solution; ultrasonically oscillating the obtained mixed system for 30 minutes, stirring for 4 hours at room temperature until the precipitate is not increased any more, filtering, washing the obtained precipitate with cold water for 3 times, and freeze-drying to obtain the microcapsule NP wrapping the pesticide pyraclostrobin₆。

TABLE 1 polyester P in the examples₁～P₆Test results of samples and PBS (polybutylene succinate)

Comparison of literature data

Sample (I)	Mn/(104g/mol)	MW/(104g/mol)	PDI	Mn 1/(104g/mol)	MW 1/(104g/mol)
						P1	5.45	9.23	1.69	1.86	3.34
P2	5.68	9.67	1.70	1.94	3.65
						P3	6.21	10.12	1.62	2.21	3.89
P4	6.54	10.65	1.63	2.45	4.36
						P5	6.81	11.56	1.69	2.32	4.67
P6	7.54	12.66	1.68	2.57	4.94
						PBS	2.54[3]	6.44	2.54	1.78[4]	2.13

[3] Synthesis and characterization of polybutadine with different relative molecular mass [ J ] engineering plastic application, 2017,45(08):11-14+24.

[4] Schick, degradation performance regulation of poly butylene succinate [ D ]. zhengzhou university, 2017.

M in Table 1_nIs the number average molecular weight, M, of the polyester_wIs the weight average molecular weight of the polyester, PDI is the molecular weight distribution, Mn, of the polyester¹And M_W ¹Number average molecular weight and weight average molecular weight, respectively, after one year of degradation in phosphate buffer solution at pH = 6.86.

TABLE 2 NP in the example₁～NP₆Properties of pyraclostrobin-loaded microcapsule particles

Sample (I)	Coating ratio (%)	Drug loading (%)	Average particle diameter (nm)	Polydispersity index	Cumulative release rate over 18 days
						NP1	75.5	37.2	91.3	0.203	60.6
NP2	79.6	40.5	96.5	0.167	62.1
						NP3	85.6	42.3	101.1	0.278	70.4
NP4	87.9	45.7	103.5	0.302	73.8
						NP5	88.8	50.4	106.0	0.307	75.2
NP6	89.2	53.8	114.7	0.348	78.5

As can be seen from the comparison of the data in table 1, the bio-based renewable chemical vanillyl alcohol and the dibasic acid derived from biomass are used as the starting materials, the molecular weight of the synthesized polyester is obviously increased compared with the polybutylene succinate PBS, and the degradation performance in a phosphate buffer solution with pH =6.86 is also obviously improved compared with the degradation performance of the polybutylene succinate. As can be seen from the comparison of the data in Table 2, the coating rate and the drug loading capacity of the pyraclostrobin microcapsule particles are increased along with the increase of the molecular weight of the polymer, because the high molecular weight polymer can more tightly coat the pyraclostrobin. Meanwhile, the average particle size of the obtained microcapsule is gradually increased, the drug release rate is correspondingly increased, and the cumulative release rate in 18 days reaches 78.5%. The microcapsule prepared by taking the polyester as a capsule wall material can solve the technical problems of the application of the existing pesticide to a certain extent, and provides a new way for the application of the pesticide.

In conclusion, the polyesters reported in the prior documents have the defects of being mostly derived from non-renewable fossil energy, difficult to naturally degrade, poor in biocompatibility and the like, and are difficult to meet the requirements of practical application on various aspects of material performance; and the existing capsule wall materials in the market also have the defects of low coating rate and drug loading rate to active molecules, poor slow release effect and the like. In view of the above problems in the prior art, the main object of the present invention is to provide a high molecular weight polyester starting from bio-based renewable chemical vanillyl alcohol, a preparation method and use as a slow release agent for pesticides. Compared with the existing polyester material, the high molecular weight polyester has the advantages of large molecular weight, good biocompatibility, easy degradation in natural environment and good service performance. Therefore, the invention relates to a 'polyester based on vanillyl alcohol derivatives, a preparation method and a use as a pesticide slow-release agent' invention patent, and the biomass vanillyl alcohol based high molecular weight polyester is used as a capsule wall material and a pesticide pyraclostrobin is used as a capsule core material to prepare the microcapsule wrapping the pesticide pyraclostrobin while maintaining non-toxicity, high stability and biodegradability. The prepared pesticide microcapsule has good coating rate, drug loading rate and slow release performance, can be buried and sowed in soil together with seeds buried underground, can sterilize and kill pests for a long time, protects the roots of crops from being damaged by diseases and insect pests in the seed development process of the crops and after the crops grow, realizes long-term utilization of the pesticide, reduces the damage to the environment, and has good market prospect.

While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention. It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.