Magnetic Janus hollow microsphere and manufacturing method and application thereof

Abstract

The invention relates to a magnetic Janus hollow microsphere and a manufacturing method and application thereof. The magnetic Janus hollow microsphere sequentially comprises a hollow part, a first shell layer and a second shell layer from inside to outside in the radial direction, the first shell layer comprises a lipophilic polymer and magnetic nanoparticles dispersed in the lipophilic polymer, the lipophilic polymer comprises a styrene monomer-based unit and a cross-linking agent-based unit, and the second shell layer comprises a styrene monomer-based unit and a cross-linking agent-based unit. The second shell layer comprises a hydrophilic polymer. The Janus hollow microsphere shows Janus characteristics and magnetism, is provided with a hollow part, is particularly suitable for substances needing to carry guests, and can be particularly used in the fields needing the microsphere to show magnetic responsiveness, for example, the Janus hollow microsphere can be widely used in various fields such as biological medicines and catalytic carriers.

Description

Technical Field

[0001] This invention relates to a magnetic Janus hollow microsphere, its manufacturing method, and its uses. Background Technology

[0002] Hollow microspheres play an important role in energy, water treatment, reaction catalysis, and drug delivery due to their unique morphology and structure. However, the hollow microspheres studied so far have been isotropic in the radial direction, which has greatly limited their functional applications.

[0003] Janus materials, combining two different components or structures and exhibiting strict partitioning, have become a research hotspot in the field of composite materials. Since Nobel laureate de Gennes proposed the concept of "Janus" in 1991, scholars both domestically and internationally have synthesized and prepared various Janus particles. Janus materials are materials with asymmetric structures, typically possessing diverse morphologies, including rod-like, sheet-like, and spherical shapes. With the development of nanotechnology, hollow microspheres with Janus properties have become a research hotspot and are in high demand in the market. The large-scale preparation and fine-scale structural control of this advanced material have become the core of technological development.

[0004] However, there are few reports on Janus microspheres with different properties on their inner and outer surfaces, i.e., exhibiting radial anisotropy.

[0005] Furthermore, for hollow microspheres, especially when the shell is relatively thin, the shell often cannot support other inorganic particles to broaden their application range. This situation is particularly prominent in the preparation of magnetic hollow microspheres. Summary of the Invention

[0006] <Problem to be solved by the invention>

[0007] In view of the above, the object of the present invention is to provide a magnetic Janus hollow microsphere that exhibits anisotropy in the radial direction and whose radial portions are precisely partitioned, is readily available, and can be easily further modified to enrich the application range of the microsphere.

[0008] The present invention also aims to provide a method for manufacturing magnetic Janus hollow microspheres. This method is simple, easy to operate, uses readily available and low-cost raw materials, and can achieve large-scale batch production. Furthermore, even with further modification, it will not significantly increase the complexity of the process.

[0009] <Solutions for solving the problem>

[0010] In view of the above situation, the inventors have discovered through in-depth research that the following solution can achieve the above-mentioned objectives of the present invention.

[0011] [1]. A magnetic Janus hollow microsphere, which has a hollow portion, a first shell and a second shell in a radial direction from the inside to the outside.

[0012] The first shell layer comprises a lipophilic polymer and magnetic nanoparticles dispersed in the lipophilic polymer, wherein the lipophilic polymer comprises units based on styrene monomers and units based on crosslinking agents.

[0013] The second shell layer contains a hydrophilic polymer.

[0014] [2]. According to [1], the magnetic Janus hollow microspheres have an average particle size of 1 to 100 μm; and / or

[0015] The total thickness of the first shell and the second shell is 20–100 nm; and / or

[0016] The thickness of the first shell layer is 15–90 nm; and / or

[0017] The thickness of the second shell is 5–10 nm; and / or

[0018] The saturation magnetization of the magnetic Janus hollow microspheres is preferably 0.5–40 emu / g.

[0019] [3]. Magnetic Janus hollow microspheres according to [1] or [2], wherein the first shell and the second shell are chemically bonded together.

[0020] [4]. Magnetic Janus hollow microspheres according to any one of [1] to [3], wherein the crosslinking agent is at least one selected from difunctional or higher vinyl aromatic hydrocarbons and difunctional or higher (meth)acrylates.

[0021] [5]. Magnetic Janus hollow microspheres according to any one of [1] to [4], wherein the particle size of the magnetic nanoparticles is 8 to 15 nm; and / or

[0022] The magnetic nanoparticles are iron oxide nanoparticles.

[0023] [6]. Magnetic Janus hollow microspheres according to any one of [1] to [5], wherein the first shell layer further comprises silicon oxide.

[0024] [7]. Magnetic Janus hollow microspheres according to [6], wherein the silicon oxide is derived from the hydrolytic condensation of siloxane groups in a silicon oxide precursor containing siloxane groups; and / or

[0025] The silica is chemically bonded to the lipophilic polymer.

[0026] [8]. Magnetic Janus hollow microspheres according to any one of [1] to [7], wherein the hydrophilic polymer comprises units based on polyoxyalkylene (meth)acrylate.

[0027] [9]. A method for manufacturing magnetic Janus hollow microspheres according to any one of [1] to [8], comprising the following steps:

[0028] (1) Prepare an aqueous phase comprising water, a surfactant and monomer A containing at least a hydrophilic monomer;

[0029] (2) Prepare an oil phase comprising an alkane solvent, a crosslinking agent, a monomer B containing at least a styrene monomer, magnetic nanoparticles and an oxidant, wherein the mass ratio of the alkane solvent to the monomer B is less than 20 / 1;

[0030] (3) The aqueous phase and the oil phase are mixed to obtain an emulsion, an aqueous solution containing a reducing agent is added to the emulsion and polymerization is carried out.

[0031]

[10] . According to the method for manufacturing magnetic Janus hollow microspheres described in [9], in step (1), the mass ratio of water to monomer A is 300 / 1 to 5 / 1; and / or

[0032] In step (1), the mass ratio of water to surfactant is 120 / 1 to 10 / 1; and / or

[0033] In step (1), the surfactant is at least one selected from styrene-maleic anhydride copolymer hydrolysate, sodium alkyl sulfate, sodium alkylphenol polyoxyethylene ether carboxylate, sodium fatty alcohol polyoxyethylene ether sulfate, and fatty alcohol polyoxyethylene ether carboxylate; and / or

[0034] In step (1), the hydrophilic monomer comprises polyoxyalkylene (meth)acrylate.

[0035]

[11] . The method for manufacturing magnetic Janus hollow microspheres according to [9] or

[10] , wherein, in step (2), the mass ratio of the alkane solvent to the monomer B is 2 / 1 or more; and / or

[0036] In step (2), the mass ratio of monomer B to crosslinking agent is 20 / 1 to 5 / 1; and / or

[0037] In step (2), the mass ratio of the alkane solvent to the magnetic nanoparticles is 200 / 1 to 20 / 1; and / or

[0038] In step (2), the mass ratio of monomer B to oxidant is 25 / 1 to 5 / 1.

[0039]

[12] . A method for manufacturing magnetic Janus hollow microspheres according to any one of [9] to

[11] , wherein, in step (2), the monomer B further comprises a silane coupling agent containing double bonds.

[0040]

[13] . According to the method for manufacturing magnetic Janus hollow microspheres as described in

[12] , the mass ratio of the alkane solvent to the silane coupling agent containing double bonds is 200 / 1 to 10 / 1; and / or

[0041] The mass ratio of the styrene monomer to the silane coupling agent containing double bonds is 50 / 1 to 1 / 1.

[0042]

[14] . A method for manufacturing magnetic Janus hollow microspheres according to any one of [9] to

[13] , wherein, in step (3), the volume ratio of the aqueous phase to the oil phase is 3 / 1 to 1 / 1; and / or

[0043] In step (3), the mass ratio of the oxidant to the reducing agent is 4 / 5 to 1 / 1; and / or

[0044] In step (3), the polymerization reaction temperature is 10-50℃ and the polymerization reaction time is 10-120 min.

[0045]

[15] . Use of magnetic Janus hollow microspheres according to any one of [1] to [8] for loading guest substances.

[0046] <The Effects of the Invention>

[0047] This invention provides a magnetic Janus hollow microsphere having two shells with different properties, thereby exhibiting radial anisotropy and precise partitioning of the radial portions. Furthermore, this magnetic Janus hollow microsphere can be easily further modified to possess both polymer and silica properties, thus expanding the range of applications using this microsphere.

[0048] Therefore, the magnetic Janus hollow microspheres of the present invention can be used to load guest substances, especially in scenarios where microspheres need to exhibit magnetic responsiveness, and thus can be widely used in many fields such as biomedicine or catalytic carriers.

[0049] In particular, the structure of the magnetic Janus hollow microspheres of the present invention (e.g., the ratio of two shells with different properties, the size of the formed hollow portion, etc.) is highly adjustable and can be customized to suit the environment and the object being processed. Therefore, even with thin shells (e.g., nanoscale), the magnetic nanoparticles can be uniformly dispersed in the shells to achieve stable magnetic responsiveness.

[0050] Furthermore, in the structure of the magnetic Janus hollow microspheres of the present invention, there may be chemical bonds between the first shell and the second shell, and / or between silicon oxide and the first shell, which further improves the structural stability of the hollow microspheres.

[0051] In addition, the present invention can also provide a method for manufacturing the above-mentioned magnetic Janus hollow microspheres. The method is simple, easy to operate, uses readily available and low-cost raw materials, and can achieve large-scale batch preparation. Even with further modification, it will not significantly increase the complexity of the process. Attached Figure Description

[0052] Figure 1 An exemplary structural diagram of the hollow microspheres of the present invention is shown.

[0053] Figure 2 SEM images of the dried magnetic hollow microspheres obtained in Example 1 are shown.

[0054] Figure 3 A photograph shows the magnetic hollow microspheres obtained in Example 1 being attracted by a magnet. Detailed Implementation

[0055] Various exemplary embodiments, features, and aspects of the present invention will be described in detail below. The term "exemplary" as used herein means "serving as an example, embodiment, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as superior to or better than other embodiments.

[0056] Furthermore, to better illustrate the present invention, numerous specific details are set forth in the following detailed embodiments. Those skilled in the art should understand that the present invention can be practiced without certain specific details. In other instances, methods, means, apparatus, and steps well known to those skilled in the art have not been described in detail in order to highlight the spirit of the present invention.

[0057] Unless otherwise stated, all units used in this specification are international standard units, and all numerical values ​​and ranges appearing in this invention should be understood to include systematic errors that are unavoidable in industrial production.

[0058] In this specification, the word "may" has two meanings: to perform a certain process and not to perform a certain process.

[0059] In this specification, references to "some specific / preferred embodiments," "other specific / preferred embodiments," "implementation," etc., refer to specific elements (e.g., features, structures, properties, and / or characteristics) related to that embodiment, which are included in at least one of the embodiments described herein and may or may not be present in other embodiments. Furthermore, it should be understood that these elements may be combined in any suitable manner in various embodiments.

[0060] In this specification, the range of values ​​referred to as "value A to value B" refers to the range including the endpoint values ​​A and B.

[0061] In this specification, the numerical ranges indicated by "above" and "below" refer to the ranges including the endpoint values. The numerical ranges indicated by "greater than" and "less than" refer to the ranges excluding the endpoint values.

[0062] In this specification, "optional" or "optionally" means that the event or situation described below may or may not occur, and the description includes both the scenario in which the event occurs and the scenario in which the event does not occur.

[0063] In this manual, the term "particle size" unless otherwise specified refers to "average particle size," which can be measured using a laser particle size analyzer to determine the average particle size and its distribution.

[0064] All unit names used in this manual are international standard unit names, and unless otherwise specified, "%" indicates mass percentage content.

[0065] In this specification, repeating units formed directly by monomer polymerization, as well as units formed by chemically converting part or all of the substituents of repeating units formed by monomer polymerization into other substituents, are collectively referred to as "units".

[0066] In this specification, the term "(meth)acrylate" as used includes both "methacrylate" and "acrylate"; and the term "(meth)acrylic acid" as used includes both "methacrylic acid" and "acrylic acid".

[0067] <Magnetic Janus Hollow Microspheres>

[0068] The magnetic Janus hollow microspheres of the present invention have, in a radial direction from the inside out, a hollow portion, a first shell and a second shell, wherein the first shell comprises an oleophilic polymer, the oleophilic polymer comprising units based on styrene monomers and units based on crosslinking agents, and the second shell comprises a hydrophilic polymer.

[0069] The following will describe each part in detail.

[0070] (Structure of magnetic Janus hollow microspheres)

[0071] In this invention, the term "microsphere" refers to an object that is generally spherical or quasi-spherical in shape. The first shell of the magnetic Janus hollow microsphere contains an oleophilic polymer, thus exhibiting oleophilicity. The second shell of the magnetic Janus hollow microsphere contains a hydrophilic polymer, thus exhibiting hydrophilicity. Therefore, anisotropy is exhibited in the radial direction of the hollow microsphere.

[0072] Figure 1 An exemplary structural diagram of the hollow microspheres of the present invention is shown, specifically, Figure 1 The image exemplarily shows the positions of the hollow portion, the first shell, and the second shell (magnetic particles and other substances that may be contained in the shells, such as silicon oxide, are not shown).

[0073] There are no particular restrictions on the specific structure of the magnetic Janus hollow microspheres; they can be adjusted appropriately according to application requirements.

[0074] In some preferred embodiments, the average particle size of the magnetic Janus hollow microspheres is preferably 1 to 100 μm, more preferably 10 to 50 μm.

[0075] In some preferred embodiments, from the viewpoint of maximizing the hollow portion, the total thickness of the first shell and the second shell is preferably 20-100 nm, more preferably 25-60 nm, and even more preferably 30-50 nm.

[0076] There are no particular limitations on the thickness of the first and second shells. In some specific embodiments, the thickness of the first shell is preferably 15–90 nm, more preferably 20–50 nm. In other specific embodiments, the thickness of the second shell is preferably 5–10 nm, more preferably 5–8 nm.

[0077] In this invention, in addition to the first shell and the second shell, the hollow microspheres of this invention may also have at least one other shell, such as other shells located between the first shell and the hollow portion or between the first shell and the second shell, other hydrophilic shells or oleophilic shells located on the side of the second shell opposite to the first shell, etc.

[0078] In addition, in some preferred embodiments, there is a chemical bond between the first shell and the second shell.

[0079] Furthermore, in some preferred embodiments, the saturation magnetization of the magnetic Janus hollow microspheres of the present invention is preferably 0.5–40 emu / g. In the present invention, the saturation magnetization is measured by a vibrating sample magnetometer.

[0080] (First shell)

[0081] In this invention, the first shell layer comprises a lipophilic polymer, which includes styrene-based monomer-based units and crosslinking agent-based units.

[0082] Examples of styrene monomers include, but are not limited to, styrene, p-methylstyrene, o-methylstyrene, chloromethylstyrene, benzylchlorostyrene, etc. These monomers can be used alone or in combination of two or more. In some preferred embodiments, styrene is preferably used.

[0083] Examples of crosslinking agents include, but are not limited to, difunctional or higher vinyl aromatic hydrocarbons, difunctional or higher vinyl ethers, and difunctional or higher (meth)acrylates. These crosslinking agents can be used alone or in combination of two or more. In some preferred embodiments, from the viewpoint of more easily obtaining hollow microspheres and reducing costs, the crosslinking agent is preferably at least one selected from difunctional or higher vinyl aromatic hydrocarbons and difunctional or higher (meth)acrylates, more preferably including vinyl aromatic hydrocarbons.

[0084] Examples of vinyl aromatic hydrocarbons with more than two functionalities include divinylbenzene, trivinylbenzene, and divinylnaphthalene.

[0085] There are no particular limitations on examples of (meth)acrylates with more than two functionalities, but difunctional to hexafunctional (meth)acrylates are preferred, such as difunctional (meth)acrylates, like ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, 1 4-Butanediol di(meth)acrylate, pentanediol di(meth)acrylate, etc.; trifunctional (meth)acrylates, such as pentaerythritol tri(meth)acrylate, trihydroxymethane tri(meth)acrylate, and glycerol tri(meth)acrylate, etc.; tetrafunctional (meth)acrylates, such as pentaerythritol tetra(meth)acrylate; pentafunctional (meth)acrylates, such as dipentaerythritol penta(meth)acrylate; hexafunctional (meth)acrylates, such as dipentaerythritol hexa(meth)acrylate, etc.

[0086] In this invention, the first shell layer comprises magnetic nanoparticles dispersed in a lipophilic polymer. The magnetic nanoparticles are true spherical or nearly spherical, and the particle size of the magnetic nanoparticles is preferably 10–30 nm. There are no particular limitations on the type of magnetic nanoparticles, but they are preferably iron(III) oxide (Fe3O4) nanoparticles.

[0087] Furthermore, in order to improve the affinity between inorganic nanoparticles and lipophilic polymers, magnetic nanoparticles can also be modified to be lipophilic using methods known in the art.

[0088] In some preferred embodiments, the content of magnetic nanoparticles is preferably 1 to 50% by mass, more preferably 5 to 30% by mass, relative to 100% by mass of the total mass of the lipophilic polymer.

[0089] Additionally, the first shell layer may optionally contain silicon oxide. There are no particular limitations on the specific structure of the silicon oxide. In some preferred embodiments, from the viewpoint of readily obtaining the hollow microspheres of the present invention, the silicon oxide is derived from the hydrolytic condensation of siloxane groups in a silicon oxide precursor containing siloxane groups.

[0090] In some preferred embodiments, the silica precursor containing siloxane groups is formed by polymerization of a monomer comprising a silane coupling agent containing double bonds. In other preferred embodiments, the silica is chemically bonded to the lipophilic polymer.

[0091] There are no particular limitations on silane coupling agents containing double bonds. Specific examples of silane coupling agents containing double bonds include, but are not limited to, 3-((meth)acryloyloxy)propyltrimethoxysilane, 3-((meth)acryloyloxy)propyltriethoxysilane, 3-((meth)acryloyloxy)propyltripropoxysilane, 3-((meth)acryloyloxy)propyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltrichlorosilane, allyltrimethoxysilane, allyltriethoxysilane, allyltrichlorosilane, 3-allyltrimethoxysilane, 3-allyltriethoxysilane, 3-allyltrichlorosilane, etc. These silane coupling agents can be used alone or in combination of two or more.

[0092] In some specific embodiments, the lipophilic polymer can be a lipophilic polymer comprising units chemically bonded to silica. In this case, the silica precursor containing siloxane groups is a lipophilic polymer precursor comprising units based on styrene monomers, units based on crosslinking agents, units based on silane coupling agents containing double bonds, and optionally units based on other monomers described below. The aforementioned chemically bonded silica units are formed by the hydrolytic condensation of the siloxane groups in the lipophilic polymer precursor, thus forming a chemically bonded silica lipophilic polymer.

[0093] When the first shell contains silicon oxide, the silicon oxide can be dispersedly distributed in the first shell.

[0094] In addition, the lipophilic polymer optionally includes units based on monomers other than styrene monomers and silane coupling agents containing double bonds.

[0095] In some specific embodiments, other monomers may be other lipophilic monomers, such as monofunctional (meth)acrylate monomers. In other specific embodiments, without impairing the effects of the invention, the lipophilic polymer may further include units based on hydrophilic monomers. Generally, the content of units based on hydrophilic monomers is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 0% by mass, relative to the total amount of all units in the lipophilic polymer.

[0096] In addition, in some particularly preferred embodiments, the first shell does not contain any other inorganic or metallic, particulate or fibrous fillers other than magnetic particles.

[0097] (Second shell)

[0098] In this invention, the second shell layer comprises a hydrophilic polymer. There are no particular limitations on the type of hydrophilic polymer, as long as it includes units based on hydrophilic monomers.

[0099] In this invention, as long as the hydrophilic monomer has a hydrophilic group, there is no particular limitation on the specific type of hydrophilic monomer, and it can be selected according to actual needs. Here, the hydrophilic group is preferably at least one of hydroxyl, amino, ether, carboxyl, or their anhydrides or salts.

[0100] Specific examples of hydrophilic monomers typically include, but are not limited to: acrylamides, such as acrylamide; (meth)acrylic acids, such as acrylic acid, methacrylic acid, their anhydrides or salts; (meth)acrylates, such as polyoxyalkylene (meth)acrylates like polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, polybutylene glycol (meth)acrylate, etc.; and thiol monomers having a hydrophilic group, wherein the hydrophilic group can be at least one of hydroxyl, amino, ether, carboxyl, or their anhydrides or salts, for example, thiol carboxylic acids such as mercaptoacetic acid, mercaptopropionic acid, mercaptohexanoic acid, mercaptodecanoic acid, mercaptododecanoic acid, etc.; thiol amines such as mercaptoethylamine, mercaptopropylamine, mercaptobutylamine, etc.; and thiol ethers such as thiol polyethylene oxides of different molecular weights (e.g., molecular weight Mw: 200–20000), etc. These hydrophilic monomers can be used alone or in combination of two or more.

[0101] In some preferred embodiments, the hydrophilic monomer is preferably at least one selected from acrylamides, (meth)acrylic acids, mercaptocarboxylic acids, mercaptoamines, and mercaptoethers. In some more preferred embodiments, the hydrophilic monomer preferably comprises (meth)acrylic acids, and more preferably comprises polyoxyalkylene (meth)acrylates.

[0102] As needed, the hydrophilic polymer may also include units based on other monomers. In some specific embodiments, the other monomers may be lipophilic monomers without impairing the effects of the invention. Generally, the content of lipophilic monomer-based units is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 0% by mass, relative to the total amount of all units in the hydrophilic polymer.

[0103] In addition, depending on the manufacturing method used, the second shell may optionally contain surfactants, such as macromolecular emulsifiers, macromolecular stabilizers, and other macromolecular surfactants.

[0104] Furthermore, in some preferred embodiments, the second shell is non-crosslinked; in other words, the hydrophilic polymer does not include crosslinking agent-based units.

[0105] Furthermore, when there is a chemical connection between the first shell and the second shell, each of the first shell and the second shell has a connected polymer near the interface between the two shells, comprising units based on the monomers forming the first shell (e.g., the aforementioned styrene monomers, crosslinking agents, silane coupling agents, other monomers, etc.) and units based on the monomers forming the second shell (e.g., the aforementioned hydrophilic monomers and lipophilic monomers, etc.).

[0106] In this invention, there are no particular limitations on the method for manufacturing the magnetic Janus hollow microspheres, and various methods commonly used in the art can be employed. However, from the viewpoint of more easily obtaining the magnetic Janus hollow microspheres of this invention, the magnetic Janus hollow microspheres of this invention are preferably obtained by interfacial emulsion polymerization.

[0107] In some preferred embodiments, from the viewpoint of more easily obtaining the magnetic Janus hollow microspheres of the present invention, the magnetic Janus hollow microspheres of the present invention are obtained by the method described in the <Method for Manufacturing Magnetic Janus Hollow Microspheres> described later.

[0108] (Other parts)

[0109] The magnetic Janus hollow microspheres of the present invention can be further modified within the hollow portion. For example, a functional polymer is preferably grafted onto the inner wall of the hollow portion.

[0110] Depending on the specific type of functional polymer grafted, the hollow portion of the magnetic Janus hollow microspheres of the present invention can possess different functionalities. For example, when grafted with an oleophilic functional polymer, the magnetic Janus hollow microspheres can exhibit excellent adsorption properties for oleophilic substances; when grafted with a hydrophilic functional polymer, the magnetic Janus hollow microspheres can exhibit excellent adsorption properties for hydrophilic substances. Of course, it is understood that the properties imparted by the functional polymer are not limited to these.

[0111] <Manufacturing Method of Magnetic Janus Hollow Microspheres>

[0112] The method for manufacturing magnetic Janus hollow microspheres of the present invention includes the following steps: (1) preparing an aqueous phase comprising water, a surfactant and monomer A containing at least a hydrophilic monomer; (2) preparing an oil phase comprising an alkane solvent, a crosslinking agent, monomer B containing at least a styrene monomer, magnetic nanoparticles and an oxidant, wherein the mass ratio of the alkane solvent to the monomer B is 20 / 1 or less; (3) mixing the aqueous phase and the oil phase to obtain an emulsion, adding an aqueous solution containing a reducing agent to the emulsion and performing polymerization.

[0113] As can be seen, the method for manufacturing magnetic Janus hollow microspheres of the present invention is based on interfacial emulsion polymerization, which initiates free radical polymerization through redox reaction, and forms hollow microspheres by polymerization at the oil-water interface.

[0114] The steps will be explained in detail below.

[0115] (Step (1))

[0116] In step (1), an aqueous phase comprising water, a surfactant, and monomer A is prepared, wherein monomer A contains at least a hydrophilic monomer. In some preferred embodiments, the surfactant and monomer A are dissolved in water.

[0117] In this invention, unless otherwise stated, the term "monomer" refers to a compound that is capable of polymerization and has only one polymerizable structure in its structure.

[0118] Furthermore, without compromising the technical effects of the present invention, monomer A may optionally contain other monomers.

[0119] Details of the hydrophilic monomers and optional other monomers are as described above in <Magnetic Janus Hollow Microspheres>.

[0120] In this invention, there is no particular limitation on the mass ratio of water to monomer A, because the polymerization is mainly driven by the polymerization of monomer B in the oil phase. In some preferred embodiments, from the viewpoint of more easily obtaining hollow microspheres, the mass ratio of water to monomer A is preferably 300 / 1 to 5 / 1, more preferably 250 / 1 to 8 / 1, and even more preferably 200 / 1 to 20 / 1, for example, 100 / 1.

[0121] There are no particular restrictions on the type of surfactant. In some preferred embodiments, the surfactant is at least one selected from styrene-maleic anhydride copolymer hydrolysate, sodium alkyl sulfate, sodium alkylphenol polyoxyethylene ether carboxylate, sodium fatty alcohol polyoxyethylene ether sulfate, and fatty alcohol polyoxyethylene ether carboxylate.

[0122] In some preferred embodiments, from the viewpoint of being more conducive to the formation of a spherical shell, a polymeric surfactant is preferably used, and more preferably at least one selected from styrene-maleic anhydride copolymer hydrolysate and sodium fatty alcohol polyoxyethylene ether sulfate.

[0123] Styrene-maleic anhydride copolymer hydrolysates are typically used in the form of styrene-maleic anhydride copolymer hydrolysates. A styrene-maleic anhydride copolymer hydrolysate is a hydrolysate obtained by treating styrene-maleic anhydride copolymer in water with sodium hydroxide or potassium hydroxide. The concentration of the styrene-maleic anhydride copolymer hydrolysate in this hydrolysate is typically 5% to 15% by mass. Furthermore, when using a styrene-maleic anhydride copolymer hydrolysate, the amount of water it contains is calculated as part of the water-to-substance ratio.

[0124] In some preferred embodiments, from the viewpoint of more easily obtaining hollow microspheres, the mass ratio of water to surfactant is preferably 120 / 1 to 10 / 1, more preferably 110 / 1 to 15 / 1, and even more preferably 50 / 1 to 15 / 1, for example, 20 / 1.

[0125] Furthermore, without compromising the effects of the present invention, the aqueous phase may, as needed, contain water-soluble solvents such as methanol, ethanol, isopropanol, n-propanol, butanol, ethylene glycol, propylene glycol, diethylene glycol, pyrrolidone, etc.; inorganic stabilizers; defoamers; pH adjusters; thickeners; diluents; etc.

[0126] (Step (2))

[0127] In step (2), an oil phase is prepared comprising an alkane solvent, a crosslinking agent, monomer B, magnetic nanoparticles and an oxidant, wherein the mass ratio of the alkane solvent to the monomer B is less than 20 / 1, and the monomer B contains at least a styrene monomer.

[0128] There is no particular limitation on the type of alkane solvent, as long as it can dissolve monomer B and the crosslinking agent. Specific examples of alkane solvents include, but are not limited to, butane, pentane, n-hexane, cyclohexane, n-heptane, cycloheptane, n-octane, gasoline, kerosene, paraffin, diesel, etc. These solvents can be used alone or in combination of two or more.

[0129] Although the mechanism is not yet clear, by making the mass ratio of the alkane solvent to monomer B satisfy the above range, the interfacial polymerization described below can be promoted, thereby obtaining the hollow microspheres of the present invention. However, there is no particular limitation on the lower limit of the mass ratio of the alkane solvent to monomer B. In some preferred embodiments, the mass ratio of the alkane solvent to monomer B is preferably 20 / 1 to 2 / 1, more preferably 15 / 1 to 5 / 1, such as 10 / 1.

[0130] Details of the crosslinking agent are as described in the above <Janus hollow microspheres>, and will not be elaborated here.

[0131] In some preferred embodiments, the mass ratio of monomer B to the crosslinking agent is 20 / 1 to 5 / 1, more preferably 15 / 1 to 5 / 1, such as 10 / 1.

[0132] There is no particular limitation on monomer B, as long as it contains styrenic monomers.

[0133] In some specific embodiments, the magnetic Janus hollow microspheres can be subjected to inorganic modification. In this case, monomer B also preferably contains a silane coupling agent containing a double bond.

[0134] In this case, in some preferred embodiments, the mass ratio of the alkane solvent to the silane coupling agent containing a double bond is preferably 200 / 1 to 10 / 1, more preferably 150 / 1 to 50 / 1, such as 100 / 1. In some other preferred embodiments, the mass ratio of the styrenic monomer to the silane coupling agent containing a double bond is preferably 50 / 1 to 1 / 1, more preferably 20 / 1 to 5 / 1.

[0135] In addition, without impairing the technical effects of the present invention, in addition to the styrenic monomer and the silane coupling agent containing a double bond, monomer B optionally contains other monomers.

[0136] Details of the styrenic monomer, the silane coupling agent containing a double bond, and other monomers are as described in the above <Magnetic Janus hollow microspheres>.

[0137] Details of the magnetic nanoparticles are also as described in the above <Magnetic Janus hollow microspheres>. Although there is no particular limitation, in some preferred embodiments, the mass ratio of the alkane solvent to the magnetic nanoparticles is preferably 200 / 1 to 20 / 1, more preferably 150 / 1 to 50 / 1, such as 100 / 1.

[0138] There are no particular restrictions on the type of oxidant, as long as it can function as an oxidant in a redox initiator. Examples of oxidants include, but are not limited to, organic peroxides, such as benzoyl peroxide and cumene hydroperoxide.

[0139] In some preferred embodiments, the mass ratio of monomer B to oxidant is preferably 25 / 1 to 5 / 1, more preferably 20 / 1 to 5 / 1, for example 15 / 1 or 10 / 1.

[0140] (Step (3))

[0141] In step (3), the aqueous phase and the oil phase are mixed to obtain an emulsion, and an aqueous solution containing a reducing agent is added to the emulsion and polymerization is carried out. In this emulsion, under the action of the surfactant contained in the aqueous phase, the oil phase forms oil droplets and disperses in the aqueous phase.

[0142] There are no particular restrictions on the volume ratio of the aqueous phase to the oil phase, which can be appropriately selected according to the actual application. In some preferred embodiments, the volume ratio of the aqueous phase to the oil phase is preferably 3 / 1 to 1 / 1, more preferably 2.5 / 1 to 1.5 / 1, for example 2 / 1.

[0143] There are no particular restrictions on the method of adding the oil phase; it can be added to the aqueous phase either all at once or in batches. In some preferred embodiments, the oil phase is dispersed in the aqueous phase under dynamic action (i.e., emulsification). There are no particular restrictions on the method of applying the dynamic action; for example, mechanical stirring, oscillation, vortexing, ultrasound, electric field, or magnetic field can be applied. In some preferred embodiments, the dynamic action is preferably applied by mechanical stirring. In other preferred embodiments, the emulsification time is preferably 20–180 s, more preferably 60–120 s.

[0144] There are no particular restrictions on the type of reducing agent, as long as it can function as a reducing agent in a redox initiator. Examples of reducing agents include, but are not limited to, ascorbic acid and sodium sulfite.

[0145] There are no particular restrictions on the concentration of the reducing agent in the aqueous solution; for example, it can be 0.002–0.05 g / ml, preferably 0.005–0.03 g / ml.

[0146] There are no particular restrictions on the method of adding the aqueous solution containing the reducing agent; the aqueous solution containing the reducing agent can be added to the polymerization system in one go or in batches.

[0147] In some preferred embodiments, the mass ratio of oxidant to reducing agent in the polymerization system is preferably 4 / 5 to 1 / 1, for example 9 / 10.

[0148] During polymerization, monomer B and crosslinking agent in the oil phase polymerize at the interface between the oil and aqueous phases, while monomer A and other polymers in the aqueous phase also polymerize at the interface between the oil and aqueous phases. The lipophilic polymer is induced to grow towards the oil droplets, while the hydrophilic polymer is induced to grow towards the aqueous phase, thus forming a double shell with different properties.

[0149] In addition, when the oil phase also contains a silane coupling agent with double bonds, the siloxane groups of the polymerized silane coupling agent undergo simultaneous hydrolysis and condensation to form silicon oxide.

[0150] There are no particular restrictions on the polymerization conditions; as long as polymerization can proceed, they can be adjusted as needed.

[0151] In some specific implementations, the polymerization temperature can be 10–50°C, for example, preferably 15–40°C, such as room temperature (25°C ± 2°C).

[0152] In some specific implementations, the polymerization time can be 10 to 120 minutes, for example, preferably 15 to 60 minutes, such as 20 minutes.

[0153] In addition, dynamic effects such as mechanical stirring, oscillation, vortexing, ultrasound, electric fields, or magnetic fields can be applied simultaneously with polymerization. In some preferred embodiments, the dynamic effect is preferably applied by mechanical stirring. For example, the stirring speed can be 50–200 rpm, preferably 150 rpm.

[0154] In addition, the atmosphere can be any of an inert gas atmosphere, a conventional air atmosphere, or an air atmosphere with adjusted oxygen partial pressure, but from the viewpoint that an inert gas atmosphere such as nitrogen or helium is preferred, as it is more conducive to the polymerization reaction.

[0155] (Other steps)

[0156] The method for manufacturing the magnetic Janus hollow microspheres of the present invention may further include other steps as needed. These other steps include, but are not limited to, a separation step of the magnetic Janus hollow microspheres, a washing step of the magnetic Janus hollow microspheres, and a drying step of the magnetic Janus hollow microspheres. These steps may be used individually or in combination of two or more. Depending on the need, these other steps may each be performed only once or multiple times.

[0157] The separation step of the magnetic Janus hollow microspheres can be carried out using methods known in the art, including but not limited to centrifugation to separate the hollow microspheres from the above emulsion system, and filtration of the hollow microspheres from the above emulsion systems.

[0158] The washing process for magnetic Janus hollow microspheres can be achieved using washing solvents such as ethanol and water, which do not damage the structure of the particles but can remove residual solvents, monomers, initiators, silane coupling agents, surfactants and other reaction raw materials.

[0159] The separation step of magnetic Janus hollow microspheres can be achieved using methods known in the art, including but not limited to spray drying, oven drying, freeze drying, and air drying.

[0160] <Applications of Magnetic Janus Hollow Microspheres>

[0161] The Janus hollow microspheres of the present invention exhibit Janus properties and magnetism and have a hollow portion, making them particularly suitable for applications requiring the support of guest substances, especially in fields where microspheres need to exhibit magnetic responsiveness, such as biomedicine, catalyst supports, and many other fields.

[0162] Example

[0163] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0164] <Example 1>

[0165] (Preparation of the aqueous phase)

[0166] Take 20g of water, add 5g of styrene-maleic anhydride copolymer hydrolysate with a mass concentration of 10% and 0.1g of poly(ethylene glycol) methacrylate, and wait for it to dissolve evenly to obtain the aqueous phase.

[0167] (Preparation of the oil phase)

[0168] Take 50 mg of benzoyl peroxide and add it to 10 g of n-heptane. Then add 1 g of styrene, 0.1 g of divinylbenzene, and 50 mg of n-heptane dispersion of Fe3O4 magnetic particles. Dissolve evenly to obtain the oil phase.

[0169] (polymerization)

[0170] The oil phase and the water phase are mixed and emulsified under the action of a high-speed shear homogenizer to obtain an oil-water emulsion.

[0171] Add 60 mg of ascorbic acid to 5 g of water, dissolve it evenly, and then add it dropwise to the above-mentioned emulsified emulsion. Under the conditions of room temperature and stirring at 150 rpm, carry out a redox-initiated free radical polymerization reaction. After 20 min, stop the reaction, centrifuge to obtain the solid, and wash it repeatedly with water and ethanol to obtain pure polymer Janus hollow microspheres.

[0172] The hollow microspheres have an average particle size of 30 μm, a hydrophilic shell layer of 5 nm thickness, an oleophilic shell layer of 25 nm thickness, a total thickness of 30 nm, and a saturation magnetization of 5 emu / g.

[0173] <Example 2>

[0174] (Preparation of the aqueous phase)

[0175] Take 20g of water, add 1g of sodium fatty alcohol polyoxyethylene ether sulfate and 0.1g of poly(ethylene glycol) methacrylate, and let them dissolve evenly to obtain the aqueous phase.

[0176] (Preparation of the oil phase)

[0177] Take 50 mg of benzoyl peroxide and add it to 10 g of n-heptane, along with 50 mg of n-heptane dispersion of Fe3O4 magnetic particles. Then add 1 g of styrene and 0.1 g of divinylbenzene and dissolve them evenly to obtain the oil phase.

[0178] (polymerization)

[0179] The oil phase and the water phase are mixed and emulsified under the action of a high-speed shear homogenizer to obtain an oil-water emulsion.

[0180] Add 60 mg of ascorbic acid to 5 g of water, dissolve it evenly, and then add it dropwise to the above-mentioned emulsified emulsion. Under the conditions of room temperature and stirring at 150 rpm, carry out a redox-initiated free radical polymerization reaction. After 20 min, stop the reaction, centrifuge to obtain the solid, and wash it repeatedly with water and ethanol to obtain pure polymer Janus hollow microspheres.

[0181] The hollow microspheres have an average particle size of 40 μm, a hydrophilic shell layer of 5 nm as the second shell layer, an oleophilic shell layer of 25 nm as the first shell layer, a total thickness of 30 nm, and a saturation magnetization of 5 emu / g.

[0182] <Example 3>

[0183] (Preparation of the aqueous phase)

[0184] Take 20g of water, add 5g of styrene-maleic anhydride copolymer hydrolysate with a mass concentration of 10% and 0.1g of poly(ethylene glycol) methacrylate, and wait for it to dissolve evenly to obtain the aqueous phase.

[0185] (Preparation of the oil phase)

[0186] Take 50 mg of cumene hydroperoxide and add it to 10 g of n-heptane. Then add 1 g of styrene, 0.1 g of divinylbenzene, and 50 mg of n-heptane dispersion of Fe3O4 magnetic particles. Dissolve evenly to obtain the oil phase.

[0187] (polymerization)

[0188] The oil phase and the water phase are mixed and emulsified under the action of a high-speed shear homogenizer to obtain an oil-water emulsion.

[0189] Add 60 mg of ascorbic acid to 5 g of water, dissolve it evenly, and then add it dropwise to the above-mentioned emulsified emulsion. Under the conditions of room temperature and stirring at 150 rpm, carry out a redox-initiated free radical polymerization reaction. After 20 min, stop the reaction, centrifuge to obtain the solid, and wash it repeatedly with water and ethanol to obtain pure polymer Janus hollow microspheres.

[0190] The hollow microspheres have an average particle size of 30 μm, a hydrophilic shell layer of 5 nm as the second shell layer, an oleophilic shell layer of 25 nm as the first shell layer, a total thickness of 30 nm, and a saturation magnetization of 5 emu / g.

[0191] <Example 4>

[0192] (Preparation of the aqueous phase)

[0193] Take 20g of water, add 5g of styrene-maleic anhydride copolymer hydrolysate with a mass concentration of 10% and 1g of poly(ethylene glycol) methacrylate, and wait for it to dissolve evenly to obtain the aqueous phase.

[0194] (Preparation of the oil phase)

[0195] Take 250 mg of benzoyl peroxide and add it to 10 g of n-heptane. Then add 5 g of styrene, 0.5 g of divinylbenzene, and 50 mg of n-heptane dispersion of Fe3O4 magnetic particles. Dissolve evenly to obtain the oil phase.

[0196] (polymerization)

[0197] The oil phase and the water phase are mixed and emulsified under the action of a high-speed shear homogenizer to obtain an oil-water emulsion.

[0198] Add 300 mg of ascorbic acid to 5 g of water, dissolve it evenly, and then add it dropwise to the above-mentioned emulsified emulsion. Under the conditions of room temperature and stirring at 150 rpm, carry out a redox-initiated free radical polymerization reaction. After 20 min, stop the reaction, centrifuge to obtain the solid, and wash it repeatedly with water and ethanol to obtain pure polymer Janus hollow microspheres.

[0199] The hollow microspheres have an average particle size of 30 μm, a hydrophilic shell layer of 10 nm as the second shell layer, an oleophilic shell layer of 80 nm as the first shell layer, a total thickness of 90 nm, and a saturation magnetization of 1 emu / g.

[0200] <Example 5>

[0201] (Preparation of the aqueous phase)

[0202] Take 20g of water, add 5g of styrene-maleic anhydride copolymer hydrolysate with a mass concentration of 10% and 0.1g of poly(ethylene glycol) methacrylate, and let it dissolve evenly to obtain the aqueous phase.

[0203] (Preparation of the oil phase)

[0204] Add 50 mg of benzoyl peroxide to 10 g of n-hexane, then add 1 g of styrene, 0.1 g of divinylbenzene, and a n-heptane dispersion of 50 mg of Fe3O4 magnetic particles. Dissolve evenly to obtain the oil phase.

[0205] (polymerization)

[0206] The oil phase and the water phase are mixed and emulsified under the action of a high-speed shear homogenizer to obtain an oil-water emulsion.

[0207] Add 60 mg of ascorbic acid to 5 g of water, dissolve it evenly, and then add it dropwise to the above-mentioned emulsified emulsion. Under the conditions of room temperature and stirring at 150 rpm, carry out a redox-initiated free radical polymerization reaction. After 20 min, stop the reaction, centrifuge to obtain the solid, and wash it repeatedly with water and ethanol to obtain pure polymer Janus hollow microspheres.

[0208] The hollow microspheres have an average particle size of 30 μm, a hydrophilic shell layer of 5 nm as the second shell layer, an oleophilic shell layer of 25 nm as the first shell layer, a total thickness of 30 nm, and a saturation magnetization of 5 emu / g.

[0209] <Example 6>

[0210] (Preparation of the aqueous phase)

[0211] Take 20g of water, add 5g of styrene-maleic anhydride copolymer hydrolysate with a mass concentration of 10% and 0.1g of poly(ethylene glycol) methacrylate, and wait for it to dissolve evenly to obtain the aqueous phase.

[0212] (Preparation of the oil phase)

[0213] Add 50 mg of benzoyl peroxide to 10 g of n-heptane, then add 1 g of styrene, 0.1 g of divinylbenzene, and a n-heptane dispersion of 100 mg of Fe3O4 magnetic particles. Dissolve evenly to obtain the oil phase.

[0214] (polymerization)

[0215] The oil phase and the water phase are mixed and emulsified under the action of a high-speed shear homogenizer to obtain an oil-water emulsion.

[0216] Add 60 mg of ascorbic acid to 5 g of water, dissolve it evenly, and then add it dropwise to the above-mentioned emulsified emulsion. Under the conditions of room temperature and stirring at 150 rpm, carry out a redox-initiated free radical polymerization reaction. After 20 min, stop the reaction, centrifuge to obtain the solid, and wash it repeatedly with water and ethanol to obtain pure polymer Janus hollow microspheres.

[0217] The hollow microspheres have an average particle size of 30 μm, a hydrophilic shell layer of 5 nm as the second shell layer, an oleophilic shell layer of 25 nm as the first shell layer, a total thickness of 30 nm, and a saturation magnetization of 10 emu / g.

[0218] <Example 7>

[0219] (Preparation of the aqueous phase)

[0220] Take 20g of water, add 5g of styrene-maleic anhydride copolymer hydrolysate with a mass concentration of 10% and 0.1g of poly(ethylene glycol) methacrylate, and let it dissolve evenly to obtain the aqueous phase.

[0221] (Preparation of the oil phase)

[0222] Take 50 mg of benzoyl peroxide and add it to 10 g of n-heptane. Then add 1 g of styrene and 0.1 g of divinylbenzene, as well as 50 mg of n-heptane dispersion of Fe3O4 magnetic particles and 100 mg of 3-methacryloyloxypropyltrimethoxysilane (MPS). Dissolve evenly to obtain the oil phase.

[0223] (polymerization)

[0224] The oil phase and the water phase are mixed and emulsified under the action of a high-speed shear homogenizer to obtain an oil-water emulsion.

[0225] Add 60 mg of ascorbic acid to 5 g of water, dissolve it evenly, and then add it dropwise to the above-mentioned emulsified emulsion. Under the conditions of room temperature and stirring at 150 rpm, carry out a redox-initiated free radical polymerization reaction. After 20 min, stop the reaction, centrifuge to obtain the solid, and wash it repeatedly with water and ethanol to obtain pure polymer Janus hollow microspheres.

[0226] The hollow microspheres have an average particle size of 30 μm, a hydrophilic shell layer of 5 nm as the second shell layer, an oleophilic shell layer of 30 nm as the first shell layer, a total thickness of 35 nm, and a saturation magnetization of 5 emu / g.

[0227] <Example 8>

[0228] (Preparation of the aqueous phase)

[0229] Take 20g of water, add 10g of styrene-maleic anhydride copolymer hydrolysate with a mass concentration of 10% and 0.1g of poly(ethylene glycol) methacrylate, and let it dissolve evenly to obtain the aqueous phase.

[0230] (Preparation of the oil phase)

[0231] Take 50 mg of benzoyl peroxide and add it to 10 g of n-heptane. Then add 1 g of styrene, 0.1 g of divinylbenzene, and 50 mg of n-heptane dispersion of Fe3O4 magnetic particles. Dissolve evenly to obtain the oil phase.

[0232] (polymerization)

[0233] The oil phase and the water phase are mixed and emulsified under the action of a high-speed shear homogenizer to obtain an oil-water emulsion.

[0234] Add 60 mg of ascorbic acid to 5 g of water, dissolve it evenly, and then add it dropwise to the above-mentioned emulsified emulsion. Under the conditions of room temperature and stirring at 150 rpm, carry out a redox-initiated free radical polymerization reaction. After 20 min, stop the reaction, centrifuge to obtain the solid, and wash it repeatedly with water and ethanol to obtain pure polymer Janus hollow microspheres.

[0235] The hollow microspheres have an average particle size of 5 μm, a hydrophilic shell thickness of 5 nm as the second shell, an oleophilic shell thickness of 25 nm, a total thickness of 30 nm, and a saturation magnetization of 5 emu / g.

[0236] <Example 9>

[0237] (Preparation of the aqueous phase)

[0238] Take 20g of water, add 2g of styrene-maleic anhydride copolymer hydrolysate with a mass concentration of 10% and 0.1g of poly(ethylene glycol) methacrylate, and wait for it to dissolve evenly to obtain the aqueous phase.

[0239] (Preparation of the oil phase)

[0240] Take 50 mg of benzoyl peroxide and add it to 10 g of n-heptane. Then add 1 g of styrene, 0.1 g of divinylbenzene, and 50 mg of n-heptane dispersion of Fe3O4 magnetic particles. Dissolve evenly to obtain the oil phase.

[0241] (polymerization)

[0242] The oil phase and the water phase are mixed and emulsified under the action of a high-speed shear homogenizer to obtain an oil-water emulsion.

[0243] Add 60 mg of ascorbic acid to 5 g of water, dissolve it evenly, and then add it dropwise to the above-mentioned emulsified emulsion. Under the conditions of room temperature and stirring at 150 rpm, carry out a redox-initiated free radical polymerization reaction. After 20 min, stop the reaction, centrifuge to obtain the solid, and wash it repeatedly with water and ethanol to obtain pure polymer Janus hollow microspheres.

[0244] The hollow microspheres have an average particle size of 90 μm, a hydrophilic shell layer with a thickness of 5 nm as the second shell layer, an oleophilic shell layer with a thickness of 25 nm, a total thickness of 30 nm, and a saturation magnetization of 5 emu / g.

[0245] <Comparative Example 1>

[0246] (Preparation of the aqueous phase)

[0247] Take 20g of water, add 5g of styrene-maleic anhydride copolymer hydrolysate with a mass concentration of 10% and 0.1g of poly(ethylene glycol) methacrylate, and let it dissolve evenly to obtain the aqueous phase.

[0248] (Preparation of the oil phase)

[0249] Take 50 mg of benzoyl peroxide and add it to 10 g of n-heptane. Then add 0.3 g of styrene, 0.03 g of divinylbenzene, and 50 mg of n-heptane dispersion of Fe3O4 magnetic particles. Dissolve evenly to obtain the oil phase.

[0250] (polymerization)

[0251] The oil phase and the water phase are mixed and emulsified under the action of a high-speed shear homogenizer to obtain an oil-water emulsion.

[0252] Add 60 mg of ascorbic acid to 5 g of water, dissolve it evenly, and then dropwise add it to the above-mentioned emulsified emulsion. Under the conditions of room temperature and stirring at 150 rpm, carry out a redox-initiated free radical polymerization reaction. The reaction was stopped after 20 min. Due to the insufficient amount of styrene and divinylbenzene in the oil phase, Janus hollow microspheres could not be obtained.

[0253] It should be noted that although the technical solution of the present invention has been described with specific examples, those skilled in the art will understand that the present invention should not be limited thereto.

[0254] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A magnetic Janus hollow microsphere, characterized in that, It has a hollow part, a first shell and a second shell in a radial direction from the inside to the outside. The first shell layer comprises a lipophilic polymer and magnetic nanoparticles dispersed in the lipophilic polymer, wherein the lipophilic polymer comprises units based on styrene monomers and units based on crosslinking agents. The second shell layer contains a hydrophilic polymer.

2. The magnetic Janus hollow microspheres according to claim 1, characterized in that, The magnetic Janus hollow microspheres have an average particle size of 1–100 μm; and / or The total thickness of the first shell and the second shell is 20–100 nm; and / or The thickness of the first shell layer is 15–90 nm; and / or The thickness of the second shell is 5–10 nm; and / or The saturation magnetization of the magnetic Janus hollow microspheres is preferably 0.5–40 emu / g.

3. The magnetic Janus hollow microspheres according to claim 1 or 2, characterized in that, The first shell and the second shell are connected by chemical bonds.

4. The magnetic Janus hollow microspheres according to any one of claims 1 to 3, characterized in that, The crosslinking agent is at least one selected from difunctional or higher vinyl aromatic hydrocarbons and difunctional or higher (meth)acrylates.

5. The magnetic Janus hollow microspheres according to any one of claims 1 to 4, characterized in that, The magnetic nanoparticles have a particle size of 8–15 nm; and / or The magnetic nanoparticles are iron oxide nanoparticles.

6. The magnetic Janus hollow microspheres according to any one of claims 1 to 5, characterized in that, The first shell also contains silicon oxide.

7. The magnetic Janus hollow microspheres according to claim 6, characterized in that, The silicon oxide is derived from the hydrolytic condensation of siloxane groups in a silicon oxide precursor containing siloxane groups; and / or The silica is chemically bonded to the lipophilic polymer.

8. The magnetic Janus hollow microspheres according to any one of claims 1 to 7, characterized in that, The hydrophilic polymer comprises units based on polyoxyalkylene (meth)acrylates.

9. A method for manufacturing magnetic Janus hollow microspheres according to any one of claims 1 to 8, characterized in that, It includes the following steps: (1) Prepare an aqueous phase comprising water, a surfactant and monomer A containing at least a hydrophilic monomer; (2) Prepare an oil phase comprising an alkane solvent, a crosslinking agent, a monomer B containing at least a styrene monomer, magnetic nanoparticles and an oxidant, wherein the mass ratio of the alkane solvent to the monomer B is less than 20 / 1; (3) The aqueous phase and the oil phase are mixed to obtain an emulsion, an aqueous solution containing a reducing agent is added to the emulsion and polymerization is carried out.

10. The method for manufacturing magnetic Janus hollow microspheres according to claim 9, characterized in that, In step (1), the mass ratio of water to monomer A is 300 / 1 to 5 / 1; and / or In step (1), the mass ratio of water to surfactant is 120 / 1 to 10 / 1; and / or In step (1), the surfactant is at least one selected from styrene-maleic anhydride copolymer hydrolysate, sodium alkyl sulfate, sodium alkylphenol polyoxyethylene ether carboxylate, sodium fatty alcohol polyoxyethylene ether sulfate, and fatty alcohol polyoxyethylene ether carboxylate; and / or In step (1), the hydrophilic monomer comprises polyoxyalkylene (meth)acrylate.

11. The method for manufacturing magnetic Janus hollow microspheres according to claim 9 or 10, characterized in that, In step (2), the mass ratio of the alkane solvent to the monomer B is 2 / 1 or more; and / or In step (2), the mass ratio of monomer B to crosslinking agent is 20 / 1 to 5 / 1; and / or In step (2), the mass ratio of the alkane solvent to the magnetic nanoparticles is 200 / 1 to 20 / 1; and / or In step (2), the mass ratio of monomer B to oxidant is 25 / 1 to 5 / 1.

12. The method for manufacturing magnetic Janus hollow microspheres according to any one of claims 9 to 11, characterized in that, In step (2), monomer B also contains a silane coupling agent containing a double bond.

13. The method for manufacturing magnetic Janus hollow microspheres according to claim 12, characterized in that, The mass ratio of the alkane solvent to the silane coupling agent containing the double bond is 200 / 1 to 10 / 1; and / or The mass ratio of the styrene monomer to the silane coupling agent containing double bonds is 50 / 1 to 1 / 1.

14. The method for manufacturing magnetic Janus hollow microspheres according to any one of claims 9 to 13, characterized in that, In step (3), the volume ratio of the aqueous phase to the oil phase is 3 / 1 to 1 / 1; and / or In step (3), the mass ratio of the oxidant to the reducing agent is 4 / 5 to 1 / 1; and / or In step (3), the polymerization reaction temperature is 10-50℃ and the polymerization reaction time is 10-120 min.

15. Use of the magnetic Janus hollow microspheres according to any one of claims 1 to 8 for loading guest substances.

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