Aromatic anti-mosquito microcapsule as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of functional microcapsules, and discloses an aromatic anti-mosquito microcapsule as well as a preparation method and application thereof. The preparation method comprises the following steps: emulsifying a core material in a weakly alkaline aqueous solution containing an emulsifier to obtain a core material emulsion; diisocyanate and dopamine are added into the core material emulsion for a reaction, dopamine is subjected to in-situ self-polymerization to generate polydopamine, polydopamine and diisocyanate are subjected to an interface reaction, a polyurea shell material is generated, the core material is wrapped in the polyurea shell material, and the aromatic anti-mosquito microcapsule is obtained. The core material is composed of two components including mosquito-repelling plant essential oil and deet.

Description

Technical Field

[0001] The invention belongs to the technical field of functional microcapsules, and particularly relates to a fragrant mosquito-proof microcapsule and a preparation method and application thereof. Background Art

[0002] In the hot summer, mosquito bites affect people's normal life and work, and even cause many diseases, such as skin inflammation, itching, redness and swelling, etc., and there are also infectious diseases that are more harmful to humans, including dengue fever, malaria, yellow fever, filariasis, epidemic encephalitis B, etc. Commonly used mosquito repellent measures can be summarized into three categories: physical method, chemical method and biological method. The physical method mainly relies on hanging mosquito nets and is only effective in a small range to prevent mosquito bites; the chemical method mainly uses mosquito coils and mosquito repellent aerosols, etc., which have the advantages of easy use, strong effect, fast onset and long-lasting effect, and the disadvantage is that they are toxic and harmful to human health; the biological method is to indirectly or directly use natural enemies or metabolites of natural enemies.

[0003] Microcapsule technology has been used in the development and utilization of a variety of active ingredients. It has the advantages of improving the bioavailability, solubility, stability and applicability of certain bioactive compounds. Therefore, it can be used to solve the above-mentioned problems existing in existing mosquito repellents. However, existing microcapsule technology may have problems such as poor heat resistance, non-persistence and instability. Natural polymer shell materials (such as gelatin, gum arabic, alginate, etc.) are usually biocompatible, but durability and heat resistance may be insufficient. They may be easily dissolved or degraded in a humid or high temperature environment, making the microcapsules easily ruptured during washing or friction, reducing the effective time of the mosquito repellent. Microcapsules with protein bases (such as whey protein and soy protein) as shell materials have the problem of easy denaturation in high temperature environments, which affects the stability of the microcapsules. Mosquito repellent microcapsules prepared with urea-formaldehyde resin and β-cyclodextrin as wall materials have unsatisfactory capsule effects under optical microscopes, capsule particle aggregation or unstable capsule morphology. Therefore, it is necessary to develop a mosquito repellent microcapsule with good heat resistance, durability and stability. Summary of the invention

[0004] In order to overcome the shortcomings and deficiencies in the prior art, the primary purpose of the present invention is to provide a method for preparing aromatic mosquito-repellent microcapsules.

[0005] Another object of the present invention is to provide a fragrant mosquito-repellent microcapsule prepared by the above preparation method.

[0006] Another object of the present invention is to provide an application of the above-mentioned aromatic mosquito-repellent microcapsule.

[0007] Another object of the present invention is to provide a fabric finishing agent prepared from the above aromatic mosquito repellent microcapsules.

[0008] The purpose of the present invention is achieved through the following technical solutions:

[0009] A method for preparing aromatic mosquito-repellent microcapsules, comprising the following steps:

[0010] The core material is emulsified in a weak alkaline aqueous solution containing an emulsifier to obtain a core material emulsion; diisocyanate and dopamine are added to the core material emulsion for reaction, dopamine undergoes in-situ self-polymerization to generate polydopamine, and undergoes an interfacial reaction with diisocyanate to generate a polydopamine polyurea shell material to wrap the core material, thereby obtaining an aromatic mosquito-repellent microcapsule; the core material is a two-component mosquito-repellent plant essential oil and DEET.

[0011] Preferably, the diisocyanate is IPDI, MDI, TDI, HDI or a prepolymer thereof.

[0012] Preferably, the core material comprises mosquito repellent plant essential oil and DEET in a mass ratio of 1:10 to 10:1.

[0013] Preferably, the mosquito repellent plant essential oil includes eucalyptus oil, lavender oil, peppermint oil, lemongrass oil, cinnamon oil, citronella oil, camphor oil or clove oil.

[0014] Preferably, the mass ratio of the diisocyanate, the core material and dopamine is 1:1:1 to 1:20:2.

[0015] Preferably, the weakly alkaline aqueous solution containing an emulsifier includes an emulsifier gas-phase SiO2, sodium lignin sulfonate, Tween series, or Span series aqueous solution.

[0016] Preferably, the pH range of the weakly alkaline aqueous solution containing the emulsifier is pH=6 to 10.

[0017] Preferably, the temperature for reacting the diisocyanate and dopamine in the core material emulsion is 20-60° C., and the reaction time is 3-24 hours.

[0018] A kind of aromatic mosquito-proof microcapsule prepared by the above preparation method.

[0019] An application of the aromatic anti-mosquito microcapsule in mosquito repellent ointment.

[0020] A fabric finishing agent prepared from the aromatic mosquito-proof microcapsules.

[0021] Compared with the prior art, the present invention has the following advantages and effects:

[0022] (1) Compared with common polyamine cross-linking agents, the present invention uses dopamine as the reaction raw material of the polyurea shell material, and the prepared microcapsules have a higher decomposition temperature, better heat resistance and stability. In addition, polydopamine is a mussel biomimetic material that can adhere to the surfaces of various materials. The microcapsules prepared by the reaction of polydopamine and diisocyanate have a stronger adhesion ability to fabrics, which helps to improve the durability of the aromatic mosquito repellent.

[0023] (2) The mosquito repellent plant essential oil used in the present invention has aromatic properties, but its mosquito repellent effect is average. Adding the DEET component can effectively enhance the mosquito repellent ability of the core material. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is an optical microscope photograph of the microcapsules obtained in Example 1.

[0025] Figure 2 This is a scanning electron microscope photograph of the microcapsules obtained in Example 1.

[0026] Figure 3 This is a statistical distribution diagram of the particle size of the microcapsules obtained in Example 1.

[0027] Figure 4 The thermogravimetric analysis results of the microcapsules obtained in Example 1 and Comparative Example 1 are shown.

[0028] Figure 5 The microcapsules obtained in Example 1 are applied to fabric printing and dyeing. DETAILED DESCRIPTION

[0029] The present invention is further described below with reference to specific embodiments, but they should not be construed as limiting the present invention.

[0030] Embodiment 1:

[0031] A method for preparing aromatic mosquito-repellent microcapsules comprises the following steps:

[0032] (1) 0.5 g of sodium lignin sulfonate was weighed as an emulsifier and added into 100 mL of aqueous solution. The mixture was fully mixed in an ultrasonic machine to obtain an emulsifier solution. The emulsifier concentration was 0.5 wt %.

[0033] (2) 2 g of citronella essential oil and 2 g of DEET are added as core materials to the emulsifier solution obtained in step (1) to obtain a mixed solution, which is emulsified in a homogenizer: the homogenization speed is 5000 rpm, and the homogenization time is 2 min; then the pH of the solution is adjusted to 8.5 to obtain a core material emulsion containing essential oil and DEET, wherein the core material is a two-component mosquito repellent plant essential oil and DEET.

[0034] (3) Add 0.2 g of IPDI diisocyanate and 0.1 g of dopamine to the core material emulsion obtained in step (2), and continue to react at 25° C. with mechanical stirring at 200 rpm for 24 hours. During the reaction, dopamine undergoes self-polymerization in situ to generate polydopamine, and undergoes an interfacial reaction with IPDI to generate a polydopamine polyurea shell material that wraps the core material, thereby finally obtaining microcapsules; the obtained microcapsules are washed with deionized water for multiple times, and dried in air overnight to obtain aromatic mosquito repellent microcapsules.

[0035] The structure of the aromatic mosquito repellent microcapsules obtained in this example is characterized as follows: Figure 1 and Figure 2 As shown in Figure 2, the obtained microcapsules are spherical with a slightly rough outer surface, good morphological uniformity and obvious core-shell structure. Figure 3 As shown, the average diameter of the microcapsules was 1.1 ± 0.2 μm.

[0036] The physical and chemical properties of the aromatic mosquito repellent microcapsules obtained in Example 1 were tested, and the results were as follows: Thermogravimetric analysis results showed that the microencapsulated mosquito repellent essential oil showed enhanced thermal stability compared with the unencapsulated sample (e.g. Figure 4 ).

[0037] Embodiment 2:

[0038] A method for preparing aromatic mosquito-repellent microcapsules comprises the following steps:

[0039] (1) 0.5 g of sodium lignin sulfonate was weighed as an emulsifier and added into 100 mL of aqueous solution. The mixture was fully mixed in an ultrasonic machine to obtain an emulsifier solution. The emulsifier concentration was 0.5 wt %.

[0040] (2) 2 g of citronella essential oil and 2 g of DEET are added as core materials to the emulsifier solution obtained in step (1) to obtain a mixed solution, which is emulsified in a homogenizer: the homogenization speed is 5000 rpm, and the homogenization time is 2 min; then the pH of the solution is adjusted to 8.5 to obtain a core material emulsion containing essential oil and DEET, wherein the core material is a two-component mosquito repellent plant essential oil and DEET.

[0041] (3) 0.2 g IPDI and 0.2 g dopamine are added as wall materials to the core material emulsion obtained in step (2), and the reaction is continued for 24 h at 25° C. with mechanical stirring at 200 rpm. During the reaction, dopamine undergoes self-polymerization in situ to generate polydopamine, and undergoes an interfacial reaction with IPDI to generate a polydopamine polyurea shell material that wraps the core material, thereby finally obtaining microcapsules; the obtained microcapsules are washed with deionized water for multiple times, and dried in air overnight to obtain aromatic mosquito repellent microcapsules.

[0042] The structure of the aromatic mosquito repellent microcapsules obtained in Example 2 was characterized: the obtained microcapsules were spherical, with a slightly rough outer surface, and a slightly different wall material thickness compared to the microcapsule product in Example 1, with good morphological uniformity and an obvious core-shell structure.

[0043] The physical and chemical properties of the aromatic mosquito repellent microcapsules obtained in Example 2 were tested, and the results were as follows: Thermogravimetric analysis results showed that the microencapsulated mosquito repellent essential oil showed enhanced thermal stability compared with the unencapsulated sample.

[0044] Embodiment 3:

[0045] A method for preparing aromatic mosquito-repellent microcapsules comprises the following steps:

[0046] (1) 0.5 g of sodium lignin sulfonate was weighed as an emulsifier and added into 100 mL of aqueous solution. The mixture was fully mixed in an ultrasonic machine to obtain an emulsifier solution. The emulsifier concentration was 0.5 wt %.

[0047] (2) 3 g of citronella essential oil and 3 g of DEET are added as core materials to the emulsifier solution obtained in step (1) to obtain a mixed solution, which is emulsified in a homogenizer: the homogenization speed is 5000 rpm, and the homogenization time is 2 min; then the pH of the solution is adjusted to 8.5 to obtain a core material emulsion containing essential oil and DEET, wherein the core material is a two-component mosquito repellent plant essential oil and DEET.

[0048] (3) 0.2 g IPDI and 0.2 g dopamine are added as wall materials to the core material emulsion obtained in step (2), and the reaction is continued for 24 h at 25° C. with mechanical stirring at 200 rpm. During the reaction, dopamine undergoes self-polymerization in situ to generate polydopamine, and undergoes an interfacial reaction with IPDI to generate a polydopamine polyurea shell material that wraps the core material, thereby finally obtaining microcapsules; the obtained microcapsules are washed with deionized water for multiple times, and dried in air overnight to obtain aromatic mosquito repellent microcapsules.

[0049] The structure of the aromatic mosquito repellent microcapsules obtained in Example 3 was characterized: the obtained microcapsules were spherical, with a slightly rough outer surface, good morphological uniformity and an obvious core-shell structure.

[0050] The aromatic mosquito repellent microcapsules obtained in Example 3 were tested for various physical and chemical properties, and the results were as follows: Thermogravimetric analysis results showed that the core material content of the microcapsule product was slightly increased compared with that of Example 1, and the microencapsulated mosquito repellent essential oil showed enhanced thermal stability compared with the unencapsulated sample.

[0051] Comparative Example 1:

[0052] A method for preparing aromatic mosquito-repellent microcapsules, using TEPA (tetraethylenepentamine) instead of dopamine as a cross-linking agent, comprises the following steps:

[0053] (1) 0.5 g of sodium lignin sulfonate was weighed as an emulsifier and added into 100 mL of aqueous solution. The mixture was fully mixed in an ultrasonic machine to obtain an emulsifier solution. The emulsifier concentration was 0.5 wt %.

[0054] (2) 2 g of citronella essential oil and 2 g of DEET are added as core materials to the emulsifier solution obtained in step (1) to obtain a mixed solution, which is emulsified in a homogenizer: the homogenization speed is 5000 rpm, and the homogenization time is 2 min; then the pH of the solution is adjusted to 8.5 to obtain a core material emulsion containing essential oil and DEET, wherein the core material is a two-component mosquito repellent plant essential oil and DEET.

[0055] (3) Adding 0.2 g IPDI and 0.07 g TEPA as wall materials to the core material emulsion obtained in step (2), reacting at 25° C. and 200 rpm for 24 h to obtain polyurea microcapsules; washing the obtained microcapsules with deionized water for multiple times, and drying them in air overnight to obtain aromatic mosquito repellent microcapsules.

[0056] The product obtained in Comparative Example 1 was subjected to thermogravimetric analysis and compared with the product in Example 1. Figure 4 As shown, the microcapsules prepared using polydopamine polyurea in Example 1 have better thermal stability than the polyurea microcapsules in Comparative Example 1.

[0057] Effect embodiment 1:

[0058] The application research of the fabric finishing agent prepared by the aromatic mosquito repellent microcapsules obtained in Example 1 is carried out in the following steps:

[0059] (1) 2 g of the aromatic mosquito repellent microcapsules obtained in Example 1 were added to 80 ml of deionized water, and mechanical stirring was performed at 200 rpm to ensure that the microcapsules were uniformly dispersed in the water without obvious aggregation, to obtain a 20 wt % aqueous suspension of aromatic mosquito repellent microcapsules.

[0060] (2) 10 wt % polyvinyl alcohol (PVA) was used as a binder, and the microcapsule aqueous suspension was mixed with the binder solution in a ratio of 1:1 to obtain a working solution with a final microcapsule and binder concentration of 5% each.

[0061] (3) The fabric was first treated with an aqueous solution containing sodium bicarbonate (8 g / mL), and then impregnated with an essential oil component containing microcapsules after 30 minutes, and dried in air to obtain a fabric doped with microcapsules.

[0062] The structure of the fabric finishing agent prepared from the aromatic mosquito repellent microcapsules obtained above was characterized: Figure 5The microcapsules are evenly distributed on the surface of the fabric fibers, and the adhesion between these microcapsules and the fiber matrix is ​​strong. The microcapsules are spherical and dispersed on the fiber surface. The particle size distribution of the microcapsules is uniform, the surface is smooth, and there is no obvious damage or deformation, indicating that the microcapsules maintain good integrity during the preparation and processing process.

[0063] The aromatic mosquito-proof microcapsules used in the above-mentioned fabric finishing agent were replaced with the aromatic mosquito-proof microcapsules obtained in Comparative Example 1 to prepare a fabric finishing agent for comparative application research. Through comparative experiments, we found that the fabric treated with the aromatic mosquito-proof microcapsule fabric finishing agent of polydopamine polyurea in Example 1 showed a significant mosquito-repellent effect, while the mosquito-repellent performance of the fabric made of the aromatic mosquito-proof microcapsules in Comparative Example 1 was significantly insufficient under the same conditions. The difference in mosquito-repellent effect may be attributed to the protective effect of the microcapsule wall material and the slow-release characteristics of the mosquito repellent. The microcapsule structure of the fabric finishing agent of the present invention provides a more stable package for the mosquito-repellent core material, thereby maintaining its core material activity during long-term use.

[0064] Effect embodiment 2:

[0065] The mosquito repellent ointment prepared from the aromatic mosquito repellent microcapsules obtained in Example 1 was studied for application, and the results are as follows:

[0066] 50 g of beeswax and 100 mL of liquid paraffin are placed in a water bath, heated until completely melted, and the temperature is maintained at 70-75°C. Under stirring conditions, 5 mg of vitamin E oil is slowly added to ensure sufficient mixing to form a uniform liquid matrix as a carrier of mosquito repellent microcapsules; the liquid matrix is ​​taken out of the water bath, naturally cooled to 60°C, 50 mL of a 10 wt% mosquito repellent microcapsule suspension is added, and continuous stirring is performed until uniformly dispersed to obtain a liquid matrix mixture containing microcapsules; the mixture is poured into a sterile ointment tube, naturally cooled to room temperature, and sealed with a cover to obtain an aromatic mosquito repellent microcapsule mosquito repellent ointment with good stability and ductility.

[0067] The above aromatic mosquito-proof microcapsules for preparing the mosquito-proof ointment were replaced with the aromatic mosquito-proof microcapsules obtained in Comparative Example 1 to prepare mosquito-proof ointment for comparative application research. Through comparative experiments, we found that the mosquito-proof ointment prepared with the aromatic mosquito-proof microcapsules of polydopamine polyurea in Example 1 exhibited a significant mosquito-proof effect, while the mosquito-proof ointment prepared with the aromatic mosquito-proof microcapsules of Comparative Example 1 had significantly insufficient mosquito-proof performance under the same conditions. The difference in mosquito-proof effect may be attributed to the protective effect of the microcapsule wall material. The microcapsule structure of the mosquito-proof ointment of the present invention provides a more stable package for the mosquito-proof core material, thereby maintaining the activity of its core material during long-term use.

[0068] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for preparing aromatic mosquito-repellent microcapsules, characterized in that Follow these steps: The core material is emulsified in a weak alkaline aqueous solution containing an emulsifier to obtain a core material emulsion; diisocyanate and dopamine are added to the core material emulsion for reaction, dopamine undergoes in-situ self-polymerization to generate polydopamine, and undergoes an interfacial reaction with diisocyanate to generate a polyurea shell material to wrap the core material, thereby obtaining an aromatic mosquito-proof microcapsule; the core material is a two-component mosquito-repellent plant essential oil and DEET.

2. The preparation method according to claim 1, characterized in that: The diisocyanate is IPDI, MDI, TDI, HDI or a prepolymer thereof.

3. The preparation method according to claim 1, characterized in that: The core material comprises mosquito repellent plant essential oil and DEET in a mass ratio of 1:10 to 10:

1.

4. The preparation method according to claim 1, characterized in that: The mosquito repellent plant essential oils include eucalyptus oil, lavender oil, peppermint oil, lemongrass oil, cinnamon oil, citronella oil, camphor oil and clove oil.

5. The preparation method according to claim 1, characterized in that: The mass ratio of the diisocyanate, the core material and dopamine is 1:1:1 to 1:20:

2.

6. The preparation method according to claim 1, characterized in that: The pH range of the weak alkaline aqueous solution containing the emulsifier is pH=6-10, including emulsifier gas-phase SiO2, sodium lignin sulfonate, Tween series, and Span series aqueous solutions.

7. The preparation method according to claim 1, characterized in that: The temperature for reacting the diisocyanate and dopamine in the core material emulsion is 20-60° C., and the reaction time is 3-24 hours.

8. Aromatic mosquito-repellent microcapsule prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the aromatic anti-mosquito microcapsule according to claim 8 in mosquito repellent ointment.

10. A fabric finishing agent prepared from the aromatic mosquito-repellent microcapsules according to claim 8.

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