Long-acting insect-repelling fiber membrane with core-shell structure as well as preparation method and application of long-acting insect-repelling fiber membrane

Abstract

The invention discloses a long-acting insect-repelling fiber membrane with a core-shell structure as well as a preparation method and application of the long-acting insect-repelling fiber membrane, and aims to solve the key technical problems of sudden release, short lasting period and poor stress resistance of repellents in field application, slow degradation of existing carriers and the like. The long-acting insect-repelling fiber membrane is prepared through a coaxial electrospinning technology, and a shell layer of the long-acting insect-repelling fiber membrane takes environment-friendly degradable materials including polylactic acid (PLA) and polycaprolactone (PCL) as main carriers and is added with a proper amount of functional auxiliaries; the core layer takes polyethylene oxide (PEO) as a carrier, and the high-concentration repellent is encapsulated in the core layer. The obtained fiber membrane with the core-shell structure has the advantages of long-acting slow release, stress resistance and biodegradability, and can be combined with a mulching film for use to form a physical and chemical barrier, so that efficient prevention and control of pests are realized.

Description

Technical Field

[0001] This invention relates to the field of agricultural chemical technology, and more specifically to a long-lasting insect-repellent fiber membrane with a core-shell structure, its preparation method, and its application. Background Technology

[0002] North China Black-breasted Golden Beetle ( Holotrichia oblita Agricultural pests (APPs) are a major group of underground pests. Their larvae often damage the underground root systems of important crops such as peanuts, soybeans, and corn, frequently causing plant wilting, yield reduction, or even crop failure. Repellents, as an eco-friendly and green control method, have been gradually applied to prevent agricultural pests from feeding on crops and play a key role in the "push-pull" control strategy of integrated pest management. However, traditional repellents have significant shortcomings: their active ingredients are generally volatile; they have poor stability in complex field environments (high temperature, humidity, ultraviolet radiation); their repellent effect has a short duration, and frequent application is costly; their carriers are difficult to degrade, posing a risk of environmental pollution.

[0003] Some studies have already attempted to extend the release period of repellents by using microencapsulation, hydrogel sustained-release materials, or ordinary fiber membrane carriers. For example: Microencapsulation technology: Encapsulating repellents in microcapsules formed from natural macromolecules such as polysaccharides or proteins can achieve a certain controlled release effect. However, these materials generally have low mechanical strength and poor stress resistance, making them difficult to adapt to complex field environments. Furthermore, the controlled release period is limited, and the release rate is difficult to control.

[0004] Hydrogel sustained-release system: It utilizes the three-dimensional network structure of polymer gel to adsorb and release active substances. However, it is prone to dehydration and cracking under dry conditions, and the gel structure is unstable, which limits its field application.

[0005] Conventional electrospun fiber membrane carriers: Existing literature reports the use of uniaxial electrospinning technology to encapsulate repellents within fibers, achieving slow release through the fiber skeleton. While this method slows the release rate to some extent, it cannot achieve spatial separation between the repellent and the protective shell, and still faces problems such as rapid evaporation of active ingredients, poor thermal stability, and slow carrier degradation. Furthermore, the long-term residue of polymer materials in the soil affects the farmland ecological environment, contradicting the direction of green agriculture development.

[0006] In summary, there is currently a lack of repellent delivery systems that can achieve both efficient slow release and good stress resistance and biodegradability to meet the practical needs of long-term control of underground pests. Therefore, there is an urgent need to develop a novel functional material that combines controlled-release repellency, protective active substances, and biodegradability. Summary of the Invention

[0007] In view of this, the present invention develops a long-lasting insect repellent fiber membrane with slow-release function, good stress resistance and biodegradability based on coaxial electrospinning technology, so as to improve the stable release of repellent ingredients and efficient control.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: First, this invention provides a method for preparing a long-lasting insect-repellent fiber membrane with a core-shell structure, comprising the following steps: Step 1: Preparation of shell spinning solution The shell carrier was dissolved in a mixed solvent of dichloromethane and N,N-dimethylformamide, and then functional auxiliaries were added and stirred to dissolve, thus obtaining the shell spinning solution. Step 2: Preparation of core spinning solution The core layer carrier is dissolved in dichloromethane, stirred evenly, and then a repellent is added. Stirring is continued to dissolve the repellent to obtain the core layer spinning solution. Step 3: Coaxial spinning Using a coaxial electrospinning system, shell spinning solution and core spinning solution are added respectively to obtain an electrospinned fiber membrane by electrospinning. Step 4: Drying and shaping of the fiber membrane The electrospun fiber membrane is dried at room temperature to evaporate the residual solvent, resulting in a stable micro / nano fiber membrane, which is a long-lasting insect-repellent fiber membrane with a core-shell structure.

[0009] Preferably, the mass ratio of dichloromethane to N,N-dimethylformamide in the mixed solvent in step one is 7:3.

[0010] Preferably, the shell carrier in step one is polylactic acid and polycaprolactone in a mass ratio of 1:1, and the mass concentration of the shell carrier in the mixed solvent is 15%.

[0011] Preferably, the functional additive in step one is an antioxidant (such as UV-327, benzotriazole, hydroxybenzophenone), and the mass concentration of the functional additive in the mixed solvent is 1%.

[0012] Preferably, in step two, the core carrier is polyethylene oxide, and the mass concentration of the core carrier in dichloromethane is 0.5%.

[0013] Preferably, the repellent in step two is a mixture of eucalyptol and 2-ethylhexanol, the mass concentration of the repellent in dichloromethane is 200 mg / mL, and the volume ratio of eucalyptol to 2-ethylhexanol is 1:1.

[0014] Preferably, in step one, the shell carrier uses polylactic acid and polycaprolactone in a mass ratio of 1:1, and the functional additive is UV-327. In step two, the core carrier uses polyethylene oxide. In step three, the outer needle tube of the coaxial electrospinning system has an inner and outer diameter of 1.8 / 1.3 mm, and the inner needle tube has an inner and outer diameter of 0.9 / 0.6 mm. The shell solution injection rate is set to 0.60 mL / h, and the core solution injection rate is 0.15 mL / h. A positive voltage of 17.5 kV and a negative voltage of 3.5 kV are applied. The distance from the nozzle to the collector is 22 cm. The ambient temperature is 25±3 ℃, and the relative humidity is 35±2%.

[0015] Preferably, the stirring speed in steps one and two is 800 rpm, and the stirring and dissolving time is ≥8 h.

[0016] The present invention also provides a long-lasting insect-repellent fiber membrane with a core-shell structure prepared by the method described above.

[0017] The present invention also provides an application of a long-lasting insect-repellent fiber membrane with a core-shell structure prepared by the method described above in the control of underground pests. In the application process, the long-lasting insect-repellent fiber membrane with a core-shell structure is pasted onto a mulch film.

[0018] As can be seen from the above technical solution, compared with the prior art, the present invention discloses a long-lasting insect-repellent fiber membrane with a core-shell structure, its preparation method and application, which has the following beneficial effects: The technical solution of this invention utilizes coaxial electrospinning technology to construct a micro-nano-scale composite fiber structure with a core layer (repellent agent) and a shell layer (slow-release and protective material), thereby achieving effective drug loading and slow-release repellent functions.

[0019] The selection of shell material and solvent system ensures that the product has the best synergistic effect in terms of mechanical strength, biodegradability and spinning film-forming properties, providing structural support for the sustained release of repellents; the addition of functional adjuvants to the shell enhances environmental adaptability, overcomes the problem of poor stress resistance of conventional repellents, ensures the continuity of long-term sustained-release function, and improves the prospects for field application.

[0020] The core layer repellent formulation uses eucalyptol and 2-ethylhexanol in a 1:1 volume ratio, which significantly enhances the repellency against underground pests and achieves high-concentration (200 mg / mL) encapsulation, improving the release efficiency per unit area.

[0021] All components in the overall material system of this invention have good environmental friendliness and biodegradability, which meets the requirements of green agricultural development. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0023] Figure 1 The effect of different mass concentration ratios of PLA and PCL on fiber spinnability; Figure 2 The change in absorbance of the fiber membrane after adding different doses of UV-327; Figure 3 The effect of adding different doses of UV-327 on fiber film formation; Figure 4 This represents the cumulative release of the two repellent components over different time periods; Figure 5 To improve the efficiency of pest control in the field. Detailed Implementation

[0024] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] Experimental Example Optimization of preparation conditions: An experimental design was conducted with the mass concentrations of polylactic acid and polycaprolactone as variables to verify the optimal ratio. The specific design is shown in Table 1. Table 1. Composition of the shell carrier and shell solution

[0026] The results are attached. Figure 1 As shown, except for group 8, the other formulations have defects such as uneven particle size, spraying, or inability to form a film. Therefore, group 8 is the best.

[0027] The absorbance of the fiber was measured after adding different proportions (w / v, 0.5%, 1%, 2%) of UV-327 to the shell. The results showed that the UV absorbance gradually increased with the increase of UV-327 dose. Figure 2 However, the spinning effect of adding 2% UV-327 is not as good as that of 1% (); Figure 3 Therefore, it is preferable to add 1% (w / v) UV-327.

[0028] Example 1 The preparation method of a long-lasting insect-repellent fiber membrane with a core-shell structure includes the following steps: Step S1: Preparation of shell spinning solution 7.5% (w / v) of polylactic acid (PLA) and 7.5% (w / v) of polycaprolactone (PCL) were dissolved in a mixed solvent of dichloromethane (DCM) and N,N-dimethylformamide (DMF) in a mass ratio of 7:3. The mixture was stirred (800 rpm) for at least 8 hours to achieve uniformity. To enhance its UV resistance, 1% (w / v) of UV-327 was added to the solution.

[0029] Step S2: Preparation of core spinning solution Dissolve 0.5% (w / v) of polyethylene oxide (PEO) in DCM, stir well, and then add 200 mg / mL of a mixture of eucalyptol and 2-ethylhexanol (volume ratio 1:1) as a core layer repellent solution. This mixture is an effective repellent component for the target underground pest, the North China black-gill beetle.

[0030] Step S3: Setting up the electrospinning device and coaxial spinning The ET-2535X coaxial electrospinning system was selected, its core consisting of a high-voltage power supply, dual injection pumps, and a rotating collector. A coaxial nozzle structure was adopted: the outer needle tube had an inner / outer diameter of 1.8 / 1.3 mm, and the inner needle tube had an inner / outer diameter of 0.9 / 0.6 mm. The shell solution injection rate was set at 0.60 mL / h, and the core solution injection rate at 0.15 mL / h. A positive voltage of 17.5 kV and a negative voltage of 3.5 kV were applied, the distance from the nozzle to the collector was 22 cm, the ambient temperature was maintained at 25±3℃, and the relative humidity was controlled at 35±2%.

[0031] Step S4: Drying and shaping of the fiber membrane When the core-shell structured fiber membrane obtained by electrospinning is placed at room temperature (25±2℃) for 24 h, the residual solvent evaporates naturally, and a stable micro-nano fiber membrane is obtained. Step S5: Application Verification The prepared long-lasting insect-repellent fiber membrane (fiber membrane loaded with repellent) and the control (rubber stopper loaded with repellent) were combined with mulch film, and their repellent effect on the underground pest, the North China black-breasted beetle, was measured. Experimental results showed that ( Figure 4 and Figure 5 This fiber membrane can stably release repellents, effectively absorb ultraviolet light, and exhibit excellent repellent activity against the North China black-gill beetle in the field.

[0032] The various embodiments described in this specification are presented in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a long-lasting insect-repellent fiber membrane with a core-shell structure, characterized in that, Includes the following steps: Step 1: Preparation of shell spinning solution The shell carrier was dissolved in a mixed solvent of dichloromethane and N,N-dimethylformamide, and then functional auxiliaries were added and stirred to dissolve, thus obtaining the shell spinning solution. Step 2: Preparation of core spinning solution The core layer carrier is dissolved in dichloromethane, stirred evenly, and then a repellent is added. Stirring is continued to dissolve the repellent to obtain the core layer spinning solution. Step 3: Coaxial spinning Using a coaxial electrospinning system, shell spinning solution and core spinning solution are added respectively to obtain an electrospinned fiber membrane by electrospinning. Step 4: Drying and shaping of the fiber membrane The electrospun fiber membrane is dried at room temperature to evaporate the residual solvent, resulting in a stable micro / nano fiber membrane, which is a long-lasting insect-repellent fiber membrane with a core-shell structure.

2. The method for preparing a long-lasting insect-repellent fiber membrane with a core-shell structure according to claim 1, characterized in that, In step one, the mass ratio of dichloromethane to N,N-dimethylformamide in the mixed solvent is 7:

3.

3. The method for preparing a long-lasting insect-repellent fiber membrane with a core-shell structure according to claim 1, characterized in that, The shell carrier mentioned in step one is polylactic acid and polycaprolactone in a mass ratio of 1:1, and the mass concentration of the shell carrier in the mixed solvent is 15%.

4. The method for preparing a long-lasting insect-repellent fiber membrane with a core-shell structure according to claim 1, characterized in that, The functional additive mentioned in step one is an antioxidant, and the mass concentration of the functional additive in the mixed solvent is 1%.

5. The method for preparing a long-lasting insect-repellent fiber membrane with a core-shell structure according to claim 1, characterized in that, In step two, the core carrier is polyethylene oxide, and the mass concentration of the core carrier in dichloromethane is 0.5%.

6. The method for preparing a long-lasting insect-repellent fiber membrane with a core-shell structure according to claim 1, characterized in that, The repellent mentioned in step two is a mixture of eucalyptol and 2-ethylhexanol. The mass concentration of the repellent in dichloromethane is 200 mg / mL, and the volume ratio of eucalyptol to 2-ethylhexanol is 1:

1.

7. The method for preparing a long-lasting insect-repellent fiber membrane with a core-shell structure according to claim 1, characterized in that, In step four, the room temperature drying temperature is 25 ± 2 ℃, and the drying time is 24 h.

8. The method for preparing a long-lasting insect-repellent fiber membrane with a core-shell structure according to claim 1, characterized in that, In steps one and two, the stirring speed is 800 rpm and the stirring and dissolving time is ≥8 h.

9. A long-lasting insect-repellent fiber membrane with a core-shell structure prepared by the method according to any one of claims 1-8.

10. The application of the long-lasting insect-repellent fiber membrane with a core-shell structure as described in claim 9 in the control of underground pests, characterized in that, During application, the long-lasting insect-repellent fiber membrane with a core-shell structure is adhered to the mulch film.

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