Micro- and nanocapsules and methods for their preparation

Abstract

The application belongs to the technical field of microcapsules, and discloses a kind of micro-nano capsules and a preparation method thereof.The method comprises mixing a surfactant, sulfonated benzoxazine and water, heating to polymerize and solidify the sulfonated benzoxazine, and obtaining micro-nano capsules.The preparation method provided in the application is simple to operate, has high yield, and can control the size and morphology of the micro-nano capsules, which is conducive to obtaining micro-nano capsules with good comprehensive performance.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of microcapsules, and in particular, relates to a micro-nano capsule and a preparation method thereof. BACKGROUND

[0002] Micro-nano capsule technology is a technology that encapsulates solid, liquid or gaseous substances in tiny capsules, allowing these substances to be released or protected in a controlled manner. This technology can be traced back to the 1950s, and was initially applied in the fields of perfumes, essences and medicines. With the progress of science and technology, micro-nano capsule technology has gradually developed and been widely applied in food, cosmetics, agriculture, medicine and material science, etc. Although micro-nano capsule technology has made significant progress and been widely applied, there are still some problems and difficulties in practical application, which affect the further development and popularization of micro-nano capsule technology. The preparation process of conventional micro-nano capsules usually includes emulsification, solidification, drying and other steps, each step needs to strictly control the conditions, which increases the complexity of the process. The equipment for preparing micro-nano capsules usually requires high requirements, especially in large-scale production, which requires expensive and precise equipment. During the preparation of micro-nano capsules, a part of the raw materials cannot be completely coated or lost, resulting in low yield. The micro-nano capsule product may contain incompletely reacted raw materials or by-products, affecting the purity and performance of the product. The size of conventional micro-nano capsules is usually difficult to control accurately, resulting in uneven size distribution of the final product, affecting its application effect.

[0003] Therefore, it is still a key research topic to find a method for preparing micro-nano capsules that is simple to operate, has high yield, and can accurately control the size and morphology of the capsules. SUMMARY

[0004] The present application aims to at least solve one of the technical problems in the related art. To this end, one object of the present application is to provide a micro-nano capsule and a preparation method thereof. The preparation method provided in the present application is simple to operate, and can control the size and morphology of the micro-nano capsules, which is beneficial to obtain micro-nano capsules with good comprehensive performance.

[0005] In a first aspect of the present application, a preparation method of a micro-nano capsule is provided. According to an embodiment of the present application, the method comprises: mixing a surfactant, a sulfonated benzoxazine and water, and heating to make the sulfonated benzoxazine polymerize and solidify, to obtain a micro-nano capsule.

[0006] According to the preparation method of the above-mentioned embodiments of the present application, by dissolving the surfactant and the sulfonated benzoxazine together in water, in the process of heating, the sulfonated benzoxazine molecules first undergo ring-opening reaction to generate active intermediates of hydroxymethyl phenol, and these intermediates further polymerize to form a three-dimensional cross-linked network with high mechanical strength and thermal stability. Among them, the sulfonic acid groups in the sulfonated benzoxazine molecules do not participate in the reaction in the polymerization process, but remain in the polymer network, increasing the hydrophilicity and solubility of the polymer. And the surfactant is an amphiphilic molecule with a hydrophilic head and a hydrophobic tail. In water, surfactant molecules tend to spontaneously form micelles with hydrophilic heads facing outwards and hydrophobic tails facing inwards. This spontaneous formation feature enables the surfactant to be stably wrapped in the polymer network to form a microsphere structure, reducing additional operation steps and improving the simplicity and yield of the operation. The sulfonic acid groups in the sulfonated benzoxazine molecules can interact with the hydrophilic heads of the surfactant molecules through van der Waals forces and intermolecular hydrogen bonds to form stable physical connections, limiting the diffusion and flow of surfactant molecules, so that the microsphere structure is not easily broken or deformed in the polymerization process, which is conducive to maintaining the morphology and size of the microspheres, reducing the unevenness in the polymerization process, improving the structural stability of the micro-nano capsules, and also helping to control the size and morphology of the micro-nano capsules. In addition, since the surfactant molecules are stably wrapped in the polymer network, the loss of surfactant molecules and the introduction of impurities are reduced, thereby improving the purity of the micro-nano capsules. Thus, the preparation method provided by the present application has the advantages of simple operation, high yield, and the ability to control the size and morphology of the micro-nano capsules, which is conducive to obtaining micro-nano capsules with good performance.

[0007] In addition, the preparation method according to the above-mentioned embodiments of the present application can also have the following additional technical features:

[0008] In some embodiments of the present application, the molar mass of the sulfonated benzoxazine is not more than 1 mol. Thus, the rate of polymerization reaction can be controlled to avoid uneven or uncontrollable reactions caused by too fast polymerization, thereby forming uniform micro-nano capsules.

[0009] In some embodiments of the present application, the sulfonated benzoxazine includes at least one of chemical structure I, chemical structure II and chemical structure III:

[0010]

[0011] Thus, it is conducive to obtaining micro-nano capsules with excellent comprehensive performance.

[0012] In some embodiments of the present application, the molar mass of the surfactant is no more than 1 mol. Thereby, the formation of micelles with uniform size is promoted, and the micelles serve as templates for the polymerization reaction. The uniformity of the size of the micelles leads to a more uniform polymerization reaction on the surface of each micelle, which is conducive to the formation of micro-nano capsules with uniform size.

[0013] In some embodiments of the present application, the surfactant comprises at least one of sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, and sodium lauroyl glutamate. Thereby, the formation of micelles with uniform size is promoted, and the micelles serve as templates for the polymerization reaction. The uniformity of the size of the micelles leads to a more uniform polymerization reaction on the surface of each micelle, which is conducive to the formation of micro-nano capsules with uniform size.

[0014] In some embodiments of the present application, the volume of the water is 10 mL to 1000 mL. Thereby, the local concentration of the reactants is increased, which is conducive to a faster polymerization reaction and the formation of uniform micro-nano capsules.

[0015] In some embodiments of the present application, the temperature of the heating is 80°C to 200°C. Thereby, the ring-opening reaction of the sulfonated benzoxazine molecules is promoted, and the active intermediate of hydroxymethyl phenol is generated, which is further polymerized to form a three-dimensional cross-linked network with high mechanical strength and thermal stability, which is conducive to obtaining micro-nano capsules with good performance.

[0016] In some embodiments of the present application, the time of the heating is 1 h to 24 h. Thereby, the degree of the polymerization reaction is controlled, and over-polymerization is avoided, which is conducive to obtaining micro-nano capsules with uniform size and good performance.

[0017] In a second aspect of the present application, a micro-nano capsule is provided. According to embodiments of the present application, the micro-nano capsule is prepared by the method described above. Thereby, the micro-nano capsule has good comprehensive performance, which provides a solid foundation for its wide application in the fields of medicine, food, agriculture, cosmetics, and material science.

[0018] In some embodiments of the present application, the micro-nano capsule comprises:

[0019] a core, the material of the core comprising the surfactant;

[0020] a wall, the wall being coated on at least part of the surface of the core, the material of the wall being polymerized from sulfonated benzoxazine monomers, and the material of the wall comprising at least one of chemical structural formulas (1)-(3):

[0021] Therefore, the micro-nano capsules provided in this application exhibit excellent chemical and mechanical stability, while also ensuring the structural integrity and functional diversity of the micro-nano capsules.

[0022] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0023] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0024] Figure 1 The image shows a SEM image of the micro / nano capsule of Example 1 of this application. Detailed Implementation

[0025] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0026] In a first aspect, the present invention provides a method for preparing micro / nano capsules. According to an embodiment of the present invention, the method includes: mixing a surfactant, sulfonated benzoxazine and water, and heating to polymerize and solidify the sulfonated benzoxazine to obtain micro / nano capsules.

[0027] According to the preparation method of the above-mentioned embodiments of the present application, by dissolving the surfactant and the sulfonated benzoxazine together in water, in the process of heating, the sulfonated benzoxazine molecules first undergo ring-opening reaction to generate active intermediates of hydroxymethyl phenol, and the intermediates further polymerize to form a three-dimensional cross-linked network with high mechanical strength and thermal stability. Among them, the sulfonic acid groups in the sulfonated benzoxazine molecules do not participate in the reaction in the polymerization process, but remain in the polymer network, increasing the hydrophilicity and solubility of the polymer. And the surfactant is an amphiphilic molecule with a hydrophilic head and a hydrophobic tail. In water, the surfactant molecules tend to spontaneously form micelles with the hydrophilic head facing outward and the hydrophobic tail facing inward. This spontaneous formation characteristic enables the surfactant to be stably wrapped in the polymer network to form a microsphere structure, reducing the additional operation steps. The sulfonic acid groups in the sulfonated benzoxazine molecules can interact with the hydrophilic head of the surfactant molecules through van der Waals force and intermolecular hydrogen bond to form stable physical connection, limiting the diffusion and flow of the surfactant molecules, so that the microsphere structure is not easy to break or deform in the polymerization process, which is conducive to maintaining the morphology and size of the microsphere, reducing the unevenness in the polymerization process, improving the structural stability of the micro-nano capsule, and also helping to control the size and morphology of the micro-nano capsule. Therefore, the preparation method provided by the present application has the advantages of simple operation, high yield and high purity, and can control the size and morphology of the micro-nano capsule, which is conducive to obtaining a micro-nano capsule with good comprehensive performance.

[0028] It should be noted that sulfonated benzoxazine is a compound with a specific chemical structure, which belongs to benzoxazine derivatives. The sulfonic acid group (-SO3H) is introduced through sulfonation reaction. Sulfonated benzoxazine can be prepared by various chemical synthesis methods, such as synthesizing benzoxazine monomers by Mannich reaction, and then introducing sulfonic acid groups by sulfonation reaction to increase the hydrophilicity and solubility of the molecule.

[0029] According to some specific embodiments of the present application, the molar amount of the sulfonated benzoxazine is not more than 1 mol. For example, it can be 0.1 mol, 0.3 mol, 0.5 mol, 0.7 mol, 1 mol, etc. By limiting the molar amount of sulfonated benzoxazine within the above range, the rate of polymerization reaction can be controlled to avoid uneven reaction or uncontrollable reaction caused by too fast polymerization, so that uniform micro-nano capsules can be formed. It can also affect the density and cross-linking degree of the polymer network formed in the polymerization process, and then affect the size of the micro-nano capsule, so as to improve the comprehensive performance of the micro-nano capsule.

[0030] According to some specific embodiments of the present application, the sulfonated benzoxazine comprises at least one of chemical structure I, chemical structure II and chemical structure III:

[0031]

[0032] By selecting the sulfonated benzoxazine with the above chemical structure, the sulfonated benzoxazine can undergo ring-opening polymerization reaction under high temperature conditions to form a cross-linked polymer network, similar to the formation process of phenolic resin. Specifically, the sulfonated benzoxazine molecules will undergo ring-opening reaction under high temperature conditions to generate active intermediates of methylol phenol. These intermediates further undergo polymerization reaction to form a three-dimensional cross-linked network with high mechanical strength and thermal stability, similar to the cross-linked structure of phenolic resin, so that the micro-nano capsules have better deformation resistance and stability, and are suitable for various application scenarios. Moreover, the sulfonic acid groups in the above sulfonated benzoxazine molecules significantly improve the hydrophilicity of the polymer, so that it has better solubility and dispersibility in water, and can form uniform microspheres, overcoming the problem that traditional benzoxazine is difficult to form a ball. Therefore, it is beneficial to obtain micro-nano capsules with excellent comprehensive performance.

[0033] According to some embodiments of the present application, the molar amount of the surfactant is not more than 1 mol. For example, it can be 0.1 mol, 0.3 mol, 0.5 mol, 0.7 mol, 1 mol, etc. In aqueous solution, surfactant molecules will spontaneously assemble into micelles due to their amphiphilic nature (both hydrophilic head and hydrophobic tail). The hydrophobic tail points inward and the hydrophilic head points outward. By limiting the molar amount of the surfactant within the above range, it is beneficial to form micelles with uniform size, and the uniformity of the size of the micelles as templates for the polymerization reaction will lead to more uniform polymerization reaction on the surface of each micelle, thereby facilitating the formation of micro-nano capsules with uniform size.

[0034] As an example, the surfactant includes at least one of sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, and sodium lauroyl glutamate.

[0035] According to some embodiments of the present application, the volume of water is 10 mL to 1000 mL. For example, it can be 10 mL, 50 mL, 100 mL, 300 mL, 500 mL, 800 mL, 1000 mL, etc. As a solvent, the volume of water directly affects the concentration and viscosity of the reaction system. By limiting the volume of water within the above range, it is beneficial to increase the local concentration of reactants, thereby promoting faster polymerization reaction and facilitating the formation of uniform micro-nano capsules.

[0036] According to some embodiments of the present application, the heating temperature is 80-200℃. For example, it can be 80℃, 90℃, 100℃, 150℃, 200℃, etc. By limiting the heating temperature within the above range, the ring-opening reaction of the sulfonated benzoxazine molecule is facilitated to generate the active intermediate of hydroxymethyl phenol, which is further polymerized to form a three-dimensional cross-linked network with high mechanical strength and thermal stability, thus being conducive to obtaining micro-nano capsules with good performance.

[0037] According to some embodiments of the present application, the heating time is 1-24h. For example, it can be 1h, 5h, 10h, 15h, 20h, 24h, etc. By limiting the heating time within the above range, the degree of polymerization reaction is controlled to avoid excessive polymerization, which is conducive to obtaining micro-nano capsules with uniform size, and thus is conducive to obtaining micro-nano capsules with good performance.

[0038] In the second aspect of the present application, the present application provides a micro-nano capsule. According to embodiments of the present application, the micro-nano capsule is prepared by the above method. The micro-nano capsule has good comprehensive performance, which provides a solid foundation for its wide application in multiple fields such as medicine, food, agriculture, cosmetics and material science.

[0039] According to some embodiments of the present application, the micro-nano capsule comprises a capsule core and a capsule wall, the material of the capsule core comprises the surfactant, the capsule wall is coated on at least part of the surface of the capsule core, the material of the capsule wall is polymerized from the sulfonated benzoxazine monomer, and the material of the capsule wall comprises at least one of chemical structural formulas (1)-(3):

[0040]

[0041] According to the embodiments of the present application, by adopting sulfonated benzoxazine to form the capsule wall material, the capsule wall formed by polymerization not only provides physical protection, but also ensures the structural integrity of the micro-nano capsules under various application conditions. During the preparation of the micro-nano capsules, the cross-linked network structure of the sulfonated benzoxazine formed by ring-opening polymerization reaction is similar to that of phenolic resin, which provides good chemical stability and can resist the erosion of various chemicals. The cross-linked network structure endows the micro-nano capsules with high mechanical strength, so that they can still maintain structural integrity under physical extrusion or impact. The sulfonic acid groups introduced into the sulfonated benzoxazine molecules increase the hydrophilicity of the micro-nano capsules, which have potential applications in drug delivery, catalyst carriers, adsorption materials, etc. The sulfonated benzoxazine may form a porous structure during polymerization, and these pores can increase the specific surface area of the micro-nano capsules and improve their efficiency in the fields of catalysis, adsorption, etc. The sulfonated benzoxazine polymer provides a framework to support the entire structure of the micro-nano capsules, ensuring their stability during loading and release. Thus, the micro-nano capsules provided by the present application provide good chemical and mechanical stability, and also ensure the structural integrity and functional diversity of the micro-nano capsules.

[0042] The schemes of the present disclosure will be explained below in conjunction with the examples. Those skilled in the art will understand that the following examples are only for illustration of the present disclosure and should not be regarded as limiting the scope of the present disclosure. If the specific techniques or conditions are not specified in the examples, they are carried out according to the techniques or conditions described in the literature in the art or according to the product instructions. If the reagents or instruments are not specified by the manufacturer, they are all conventional products that can be obtained by purchase on the market.

[0043] Example 1

[0044] 0.5 mol of surfactant sodium dodecyl sulfate and 0.5 mol of sulfonated benzoxazine were weighed and dissolved in 500 mL of water. After forming a stable dispersed emulsion, the emulsion was heated at a gradient temperature to 80℃ for 12 h, and then the temperature was increased to 100℃ for 12 h to obtain a light brown solid polymer. Then, the polymer was cooled to room temperature and dried at a high temperature of 150℃ to remove residual organic matter to obtain micro-nano capsules.

[0045] In the preparation process of the micro-nano capsules of Examples 2-9 and Comparative Example 1, the remaining part is the same as Example 1 except that some experimental parameters are different.

[0046] Some experimental parameters of Examples 1-9 and Comparative Example 1 are shown in Table 1.

[0047] Table 1

[0048]

[0049] “-” means no

[0050] Testing and analysis

[0051] The micro-nano capsules obtained in Examples 1-9 and Comparative Example 1 were subjected to size determination under the same conditions. The specific test method is as follows:

[0052] Size determination: The particles were imaged using interference contrast optical microscopy. Image analysis using Image J software made it possible to obtain the size.

[0053] Figure 1 The SEM image of the micro-nano capsules of Example 1 of the present application is shown, from which the morphology of the micro-nano capsules can be observed, and by comparing the sizes of multiple particles, it is concluded that the micro-nano capsules have uniform sizes. This indicates that the preparation process can stably produce uniform particle sizes.

[0054] The test results are shown in Table 2.

[0055] Table 2

[0056]

[0057]

[0058] In combination with Table 1 and Table 2, the yield and size distribution of the micro-nano capsules obtained in Examples 1-9 compared with Comparative Example 1 can clearly show that under the combined action of the sulfonated benzoxazine molecules and the surfactant molecules, the formation quality of the micro-nano capsules is significantly improved. The sulfonic acid groups in the sulfonated benzoxazine molecules enhance the hydrophilicity of the polymer, improve its solubility and dispersibility in water, and solve the problem of difficulty in forming spheres for traditional benzoxazines. The surfactant molecules spontaneously form micelles with uniform sizes in aqueous solution due to their amphiphilic nature, which act as templates for polymerization and promote the formation of micro-nano capsules with uniform sizes. The synergistic effect of the two makes the obtained micro-nano capsules uniform, stable, and with high yield.

[0059] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "example", "specific example", "some implementation", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, the skilled person in the art can combine and combine the different embodiments or examples described in the present specification and the features of the different embodiments or examples without contradiction.

[0060] Although the embodiments of the present application have been shown and described above, it is understood that the above-described embodiments are exemplary and are not to be construed as limiting the present application, and that changes, modifications, substitutions and variations can be made by those skilled in the art without departing from the scope of the present application.

Claims

1. A method for preparing micro- or nano-capsules, characterized in that, The application relates to a method for preparing micro-nano capsules. The method comprises the following steps: mixing a surfactant, a sulfonated benzoxazine and water, and heating to make the sulfonated benzoxazine polymerize and solidify, so as to obtain the micro-nano capsules. The sulfonated benzoxazine comprises at least one of chemical structural formula I, chemical structural formula II and chemical structural formula III. ； I II III The surfactant comprises at least one of sodium dodecyl sulfate, sodium dodecyl benzene sulfonate and sodium lauroyl glutamate.

2. The production method according to claim 1, characterized by, The molar mass of the sulfonated benzoxazine is not more than 1 mol.

3. The preparation method according to claim 1, characterized in that, The molar mass of the surfactant is not more than 1 mol.

4. The production method according to claim 1, characterized by, The volume of the water is 10 mL-1000 mL.

5. The method of claim 1, wherein, The heating temperature is 80 DEG C-200 DEG C.

6. The method of claim 1, wherein, The heating time is 1 h-24 h.

7. A micro- or nanocapsule, characterized in that, The micro-nano capsules are prepared by the method in any one of claims 1-6.

8. The micro- or nano-capsule according to claim 7, characterized in that, The application also relates to a micro-nano capsule. The material of the capsule core comprises the surfactant. The capsule wall is coated on at least part of the surface of the capsule core, and the material of the capsule wall is made of sulfonated benzoxazine monomers and polymerized, and the material of the capsule wall comprises at least one of chemical structural formula (1)-(3). 。

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