A kind of aromatic anti-mosquito microcapsule and its preparation method and application

Abstract

The present invention belongs to the technical field of functional microcapsules and discloses an aromatic mosquito-repellent microcapsule, its preparation method, and application. 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; adding diisocyanate and dopamine to the core material emulsion for reaction, whereby the dopamine undergoes in-situ self-polymerization to form polydopamine, which then undergoes an interfacial reaction with the diisocyanate to form a polyurea shell material that encapsulates the core material, thereby obtaining the aromatic mosquito-repellent microcapsule; the core material comprises a two-component mosquito-repellent plant essential oil and DEET.

Description

Technical Field

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

[0002] In the sweltering summer heat, mosquito bites disrupt people's daily lives and work, and can even cause a host of illnesses. Common examples include skin inflammation, itching, and swelling, as well as more serious infectious diseases such as dengue fever, malaria, yellow fever, filariasis, and Japanese encephalitis. Common mosquito repellent measures can be categorized into three categories: physical, chemical, and biological. Physical methods primarily rely on hanging mosquito nets, which are effective only within a small area. Chemical methods primarily utilize mosquito coils and aerosols, which offer advantages such as ease of use, strong, rapid, and long-lasting effects. However, they can be toxic and harmful to human health. Biological methods involve either direct or indirect use of natural enemies or their metabolites.

[0003] Microencapsulation technology has been used in the development and utilization of a variety of active ingredients, offering advantages in improving the bioavailability, solubility, stability, and applicability of certain bioactive compounds. Therefore, it can be used to address the aforementioned issues with existing mosquito repellents. However, existing microencapsulation technology may suffer from poor heat resistance, poor durability, and instability. Natural polymer shell materials (such as gelatin, gum arabic, and alginate) generally have good biocompatibility, but may lack durability and heat resistance. They can easily dissolve or degrade in humid or high-temperature environments, causing the microcapsules to break during washing or friction, reducing the effective duration of the mosquito repellent. Microcapsules using protein-based shell materials (such as whey protein and soy protein) are prone to denaturation in high-temperature environments, affecting the stability of the microcapsules. Mosquito repellent microcapsules prepared with urea-formaldehyde resin and β-cyclodextrin as wall materials exhibit unsatisfactory encapsulation effects, with problems such as aggregation of capsule particles and unstable capsule morphology when observed under an optical microscope. Therefore, it is necessary to develop mosquito repellent microcapsules with excellent 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 microcapsules.

[0007] Another object of the present invention is to provide a fabric finishing agent prepared from the above-mentioned 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 weakly alkaline aqueous solution containing an emulsifier to obtain a core material emulsion; diisocyanate and dopamine are added to the core material emulsion for reaction, and dopamine undergoes in-situ self-polymerization to generate polydopamine, which undergoes an interfacial reaction with the diisocyanate to generate a polydopamine polyurea shell material that wraps the core material, thereby obtaining aromatic mosquito-repellent microcapsules; 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 the dopamine is 1:1:1 to 1:20:2.

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

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

[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] The invention discloses an application of the aromatic anti-mosquito microcapsule in mosquito repellent ointment.

[0020] A fabric finishing agent prepared from the above-mentioned aromatic mosquito-repellent microcapsules.

[0021] The present invention has the following advantages and effects compared to the prior art:

[0022] (1) Compared with common polyamine cross-linking agents, the present invention utilizes 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 stronger adhesion 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 Statistical distribution diagram of particle size of 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 were used for fabric printing and dyeing. DETAILED DESCRIPTION

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

[0030] Example 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 to 100 mL of aqueous solution. The mixture was thoroughly mixed in an ultrasonic machine to obtain an emulsifier solution with an emulsifier concentration of 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 at a homogenization speed of 5000 rpm and a homogenization time of 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) 0.2 g of IPDI diisocyanate and 0.1 g of dopamine were added to the core material emulsion obtained in step (2), and the reaction was continued at 25° C. with mechanical stirring at 200 rpm for 24 h. During the reaction, dopamine self-polymerized in situ to form polydopamine, and reacted with IPDI at the interface to form a polydopamine polyurea shell material that wrapped the core material, thereby finally obtaining microcapsules; the obtained microcapsules were washed with deionized water several 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 was characterized as follows: Figure 1 and Figure 2 As shown in Figure 3, the obtained microcapsules are spherical with 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 non-encapsulated sample (such as Figure 4 ).

[0037] Example 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 to 100 mL of aqueous solution. The mixture was thoroughly mixed in an ultrasonic machine to obtain an emulsifier solution with an emulsifier concentration of 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 at a homogenization speed of 5000 rpm and a homogenization time of 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 were added as wall materials to the core material emulsion obtained in step (2), and the reaction was continued at 25° C. with mechanical stirring at 200 rpm for 24 h. During the reaction, dopamine self-polymerized in situ to form polydopamine, and reacted with IPDI at the interface to form a polydopamine polyurea shell material that wrapped the core material, thereby finally obtaining microcapsules; the obtained microcapsules were washed with deionized water several 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. The wall material thickness was slightly different compared with the microcapsule product in Example 1, and they had good morphological uniformity and a distinct 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 non-encapsulated sample.

[0044] Example 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 to 100 mL of aqueous solution. The mixture was thoroughly mixed in an ultrasonic machine to obtain an emulsifier solution with an emulsifier concentration of 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 at a homogenization speed of 5000 rpm and a homogenization time of 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 were added as wall materials to the core material emulsion obtained in step (2), and the reaction was continued at 25° C. with mechanical stirring at 200 rpm for 24 h. During the reaction, dopamine self-polymerized in situ to form polydopamine, and reacted with IPDI at the interface to form a polydopamine polyurea shell material that wrapped the core material, thereby finally obtaining microcapsules; the obtained microcapsules were washed with deionized water several 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 a distinct core-shell structure.

[0050] The aromatic mosquito repellent microcapsules obtained in Example 3 were subjected to various physicochemical property tests, 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 non-encapsulated 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 to 100 mL of aqueous solution. The mixture was thoroughly mixed in an ultrasonic machine to obtain an emulsifier solution with an emulsifier concentration of 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 at a homogenization speed of 5000 rpm and a homogenization time of 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) 0.2 g IPDI and 0.07 g TEPA were added as wall materials to the core material emulsion obtained in step (2), and the reaction was carried out at 25° C. and 200 rpm for 24 h to obtain polyurea microcapsules; the obtained microcapsules were washed with deionized water several times and dried 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 from the aromatic mosquito repellent microcapsules obtained in Example 1 was carried out as follows:

[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 at 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 air-dried to obtain a fabric doped with microcapsules.

[0062] The fabric finishing agent prepared from the aromatic mosquito repellent microcapsules obtained above was structurally characterized: Figure 5The microcapsules were evenly distributed on the fabric fiber surface, with strong adhesion between the microcapsules and the fiber matrix. The microcapsules were spherical and dispersed across the fiber surface. The microcapsules had a uniform particle size distribution and a smooth surface with no visible damage or deformation, demonstrating that the microcapsules maintained good integrity during preparation and processing.

[0063] The aromatic mosquito-repellent microcapsules used in the fabric finishing agent described above were replaced with the aromatic mosquito-repellent microcapsules obtained in Comparative Example 1 to prepare a fabric finishing agent for comparative application studies. This comparative experiment revealed that fabrics treated with the aromatic mosquito-repellent microcapsule fabric finishing agent containing polydopamine polyurea from Example 1 exhibited significant mosquito repellency, while fabrics prepared with the aromatic mosquito-repellent microcapsules from Comparative Example 1 exhibited significantly poor mosquito repellency under the same conditions. This difference in repellency may be attributed to the protective effect of the microcapsule wall material and the sustained-release properties of the mosquito repellent. The microcapsule structure of the fabric finishing agent of the present invention provides a more stable coating for the mosquito-repellent core material, thereby maintaining its core 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 subjected to application research, and the results are as follows:

[0066] 50 g of beeswax and 100 mL of liquid paraffin are placed in a water bath and heated until completely melted, maintaining the temperature at 70-75°C. 5 mg of vitamin E oil is slowly added while stirring to ensure thorough mixing to form a uniform liquid matrix, which serves as a carrier for mosquito repellent microcapsules. The liquid matrix is ​​removed from the water bath, naturally cooled to 60°C, and 50 mL of a 10 wt% mosquito repellent microcapsule suspension is added. The mixture is continuously stirred 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 cap to obtain an aromatic mosquito repellent microcapsule ointment with good stability and ductility.

[0067] The aromatic mosquito-repellent microcapsules used to prepare the mosquito repellent ointment were replaced with the aromatic mosquito-repellent microcapsules obtained in Comparative Example 1 to prepare a mosquito repellent ointment for comparative application studies. Through comparative experiments, we found that the mosquito repellent ointment prepared with the aromatic mosquito-repellent microcapsules containing polydopamine polyurea in Example 1 exhibited significant mosquito repellency, while the mosquito repellent ointment prepared with the aromatic mosquito-repellent microcapsules in Comparative Example 1 exhibited significantly insufficient mosquito repellency under the same conditions. This difference in mosquito repellency may be attributed to the protective effect of the microcapsule wall material. The microcapsule structure of the mosquito repellent ointment of the present invention provides a more stable coating for the mosquito repellent core material, thereby maintaining its core activity 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 considered as equivalent replacement methods and are included in the scope of protection 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 weakly alkaline aqueous solution containing an emulsifier to obtain a core material emulsion; diisocyanate and dopamine are added to the core material emulsion for reaction, whereby dopamine undergoes in-situ self-polymerization to form polydopamine, which undergoes an interfacial reaction with the diisocyanate to form a polyurea shell material that wraps the core material, thereby obtaining aromatic mosquito-repellent microcapsules; the core material is a two-component mosquito-repellent plant essential oil and DEET; The core material comprises mosquito repellent plant essential oil and DEET in a mass ratio of 1:10 to 10:1; the mosquito repellent plant essential oil comprises eucalyptus oil, lavender oil, peppermint oil, lemongrass oil, cinnamon oil, citronella oil, camphor oil or clove oil; 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 or Span series aqueous solution; The diisocyanate is IPDI, MDI, TDI, HDI or a prepolymer thereof; The mass ratio of the diisocyanate, the core material and the dopamine is 1:1:1 to 1:20:

2.

2. The preparation method according to claim 1, wherein: 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.

3. A fragrant mosquito-repellent microcapsule prepared by the preparation method according to claim 1 or 2.

4. Use of the aromatic anti-mosquito microcapsule according to claim 3 in mosquito repellent ointment.

5. A fabric finishing agent prepared from the aromatic mosquito repellent microcapsules according to claim 3.

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