A method for preparing single-layer polymer hollow spheres in one step and the prepared single-layer polymer hollow spheres

Abstract

The invention discloses a method for preparing a single-layer polymer hollow sphere in one step and the prepared hollow sphere. The method comprises: mixing an amphiphilic monomer A, a diene amphiphilic crosslinking agent B, water and a base, dissolving to form micelles, removing oxygen and filling with nitrogen, adding an organic solvent and stirring to form swollen micelles, adding an initiator to carry out microemulsion polymerization, and purifying after the reaction to obtain a single-layer polymer hollow sphere; the general structural formula of the amphiphilic monomer A is #imgabs0# and the general structural formula of the diene amphiphilic crosslinking agent B is #imgabs1# R1=‑(CH2) n ‑CH3, n=9 or 11 or 13; #imgabs2##imgabs3#The preparation method of the present invention is simple, economical, efficient and environmentally friendly, and does not require complicated post-processing steps. The obtained hollow spheres have uniform particle size, complete structure, and a single molecular layer, and the surface of the spheres has functional groups such as carboxyl groups.

Description

Technical Field

[0001] The invention relates to the technical field of polymer chemistry, and in particular to a method for preparing single-layer polymer hollow spheres in one step and the prepared single-layer polymer hollow spheres. Background Art

[0002] Polymer hollow spheres are a type of polymer spheres with a hollow structure. The particle size is usually nanometer or micrometer. They can encapsulate small molecules such as water, hydrocarbons and other volatile solvents or other compounds with special functions. Compared with other bulk materials, they have a larger specific surface area, smaller density, and special mechanical, optical, electrical and other physical properties and application value, such as nanocarriers, nanoreactors, optical materials, energy storage, biomedicine, sensors and other fields. Therefore, they have aroused great interest among scientific researchers and become a striking direction in the field of materials research.

[0003] At present, the preparation methods of polymer hollow microspheres can be roughly divided into three categories: template method, self-assembly method and microemulsion polymerization method. The use of template method to prepare polymer hollow microspheres is easy to implement and has strong versatility. The size of the hollow microspheres can be adjusted by controlling the size of the template, but this requires the removal of the template, and the process is relatively complicated. There are many factors affecting the self-assembly process, so the requirements of the block polymer self-assembly method for experimental conditions are often more stringent. The microemulsion polymerization method has simple reaction conditions, does not require a template, and is easy to synthesize in large quantities, but a large amount of surfactants need to be removed after the reaction, which pollutes the environment. The above hollow microsphere preparation methods have many advantages, but most of them have many reaction steps and the preparation process is relatively complicated.

[0004] Since Freedman et al. first reported the synthesis and application of polymerizable surfactants in 1958, polymerizable surfactants have not been widely studied until the past 20 years. The molecules of polymerizable surfactants contain polymerizable structural units, which make them not only have the function of surfactants, but also have polymerization reaction activity. In recent years, the preparation of micro-nano materials with hollow structures by self-assembly and polymerization of amphiphilic molecules has been reported. For example, Ji J, Wei Z, Jian L, et al (Guanidinium-Based Polymerizable Surfactant as a Multifunctional Molecule for Controlled Synthesis of Nanostructured Materials with Tunable Morphologies [J]. Acs Applied Materials & Interfaces. 2017, 9 (22)) designed and synthesized a guanidine-based polymerizable surfactant as a multifunctional molecule. The tunable self-assembly behavior of the guanidine head group can adjust the filling parameters of the surfactant, and the surfactant can be used as a structure-directing agent to synthesize a series of nano-silica materials with various morphologies (spherical, disc-shaped, fibrous and cocoon-shaped). However, these materials need to be calcined to obtain a hollow structure; Yang L, Huimin G, Huan Y, et al (Two-dimensional polymers with versatile functionalities via gemini monomers. [J]. Science advances. 2019, 5 (11)) synthesized an amphiphilic The gemini monomer MA-11-2-11-MA (N,N′-bis(11-(methacrylo-yloxy)undecyl)-N,N,N′,N′-tetramethylethane-diaminiumbromide) generates a highly cross-linked bilayer of independent two-dimensional network poly(MA-112-11-MA) by in situ free radical polymerization in the bilayer at the solid-liquid interface. The monomer uses microscale particles as templates to prepare two-dimensional network poly(MA-11-2-11-MA) with different microstructures, such as microspheres, microrods and microplates, but the hollow polymer structure can only be obtained by etching with highly corrosive hydrofluoric acid to remove the silica particle template. At present, there are very few reports on the preparation of single-layer polymer hollow spheres using a simple, efficient, economical and environmentally friendly polymerization method without complex post-processing.

[0005] A Chinese patent application document with publication number CN114591457A discloses a method for preparing a two-dimensional polymer using hydrogen bonding, wherein an amphiphilic monomer containing a hydrogen bond donor / acceptor is self-assembled in an aqueous solution to form a two-dimensional supramolecule, and a free radical polymerization reaction is performed in the confined space of the two-dimensional supramolecule to obtain a two-dimensional polymer; the structure of the amphiphilic monomer is shown below:

[0006]

[0007] It combines the self-assembly of amphiphilic molecules in solution with the principle of free radical polymerization, introduces hydrogen-bonding groups into amphiphilic monomers, and prepares two-dimensional polymers with a thickness of several nanometers and uniform arrangement of hydrophilic groups on the surface. However, it does not involve using it as a monomer to polymerize and prepare single-layer polymer hollow spheres. Summary of the invention

[0008] The technical problem to be solved by the present invention is to provide a one-step method for preparing single-layer polymer hollow spheres, which is simple, economical, efficient, and environmentally friendly, does not require complicated post-processing steps, and the obtained hollow spheres have uniform particle size, complete structure, and are single-molecular layers, and the surface of the spheres has functional groups such as carboxyl groups.

[0009] The present invention solves the above technical problems through the following technical means:

[0010] A method for preparing a single-layer polymer hollow sphere in one step, comprising the following steps: mixing an amphiphilic monomer A, a diene amphiphilic crosslinking agent B, water and a base, dissolving to form micelles, adding an organic solvent after deoxygenation and nitrogen filling to form swollen micelles, adding an initiator to perform microemulsion polymerization, and purifying after the reaction to obtain the single-layer polymer hollow sphere;

[0011] The general structural formulas of the amphiphilic monomer A and the diene amphiphilic crosslinking agent B are shown in Formula 1 and Formula 2, respectively:

[0012]

[0013] Where R1=-(CH2) n -CH3 n=9 or 11 or 13;

[0014]

[0015] Preferably, the structural formula of the amphiphilic monomer A is One of the following; the structural formula of the diene amphiphilic crosslinking agent B is

[0016] Preferably, in the micelles formed after dissolution, the concentration of the amphiphilic monomer A is 20 mg / mL to 35 mg / mL, the diene amphiphilic crosslinking agent B is 1 to 5% of the molar amount of the amphiphilic monomer A; and the amount of the organic solvent is the maximum capacity increase of the micelles at this concentration.

[0017] Preferably, in the micelles formed after dissolution, the concentration of the amphiphilic monomer A is 31.25 mg / mL, and the diolefin amphiphilic crosslinking agent B is 1% of the molar amount of the amphiphilic monomer A.

[0018] Preferably, the base is one of 1,1,3,3-tetramethylguanidine, triethylamine, sodium hydroxide and potassium hydroxide.

[0019] Preferably, the organic solvent is one or a mixture of more of toluene, n-hexane, n-heptane, n-octane, dodecane and hexadecane.

[0020] Preferably, the initiator comprises one of a photoinitiator, a thermal initiator, and a redox initiation system.

[0021] Preferably, the initiator is a mixture of one or more of the photoinitiators phenyl (2, 4, 6-trimethylbenzoyl) phosphate sodium salt, potassium persulfate, and sodium thiosulfate pentahydrate.

[0022] Preferably, the pH of the dissolved micelles is 8.

[0023] Preferably, the preparation method of the amphiphilic monomer A comprises the following steps:

[0024] S1, dissolving 4-aminobenzoic acid in ethanol, adding sodium triacetoxyborohydride, dodecanal or 1-decanal to react at 0°C, and then continuing the reaction at room temperature. After the reaction is completed, post-treatment is performed to obtain a solid product;

[0025] S2, mixing and dissolving the solid product in S1 with N-methylpyrrolidone, placing at 0°C, adding a mixture of acryloyl chloride or methacryloyl chloride and N-methylpyrrolidone to react, then continuing the reaction at room temperature, adding ice water and post-treating to obtain the amphiphilic monomer A.

[0026] Preferably, the purification comprises purification by dialysis.

[0027] Preferably, the dialysis purification solvent is a mixture of ethanol and water or a mixture of tetrahydrofuran and water.

[0028] Preferably, the molecular weight cutoff of the dialysis bag used for the dialysis purification is 8000-14000, the dialysis time is one week, and the solvent is changed 5 times a day.

[0029] The present invention also provides a single-layer polymer hollow sphere, which is prepared by the one-step method for preparing the single-layer polymer hollow sphere.

[0030] The method of the present invention combines the self-assembly of amphiphilic molecules with microemulsion polymerization, assembles with organic solvents to form swollen micelles in the solution through hydrophilic-hydrophobic interactions, and directly obtains polymer hollow spheres after purification after polymerization. Since the designed amphiphilic molecules contain double bonds, they can be used as emulsifiers to stabilize the emulsion, and have reactive activity to become polymer components. At the same time, diene crosslinking agents can stabilize the hollow structure, and the surface of the prepared polymer spheres contains carboxyl functional groups, which is a simple, economical, efficient, and environmentally friendly method for preparing polymer hollow spheres; the hollow spheres prepared by the one-step method have uniform particle size, complete structure, and are the characteristics of a monolayer, and the surface of the spheres has functional groups such as carboxyl, and the regulation of spherical shell thickness and mechanical properties can be achieved by replacing organic solvents with polymerizable monomers in the follow-up, which has strong application expansibility. The raw materials used in the method are cheap, the yield is high, the preparation process is simple, the repeatability is high, the polymerization uses water as the reaction medium, and it is easy to prepare a large number of polymer hollow spheres, which has the advantages of being simple, economical, efficient, and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The hydrogen nuclear magnetic resonance spectrum of the intermediate 4-dodecylaminobenzoic acid prepared in Example 1 of the present invention;

[0032] Figure 2 This is the hydrogen nuclear magnetic resonance spectrum of the amphiphilic monomer A1 prepared in Example 1 of the present invention;

[0033] Figure 3 This is the hydrogen nuclear magnetic resonance spectrum of the diene amphiphilic crosslinking agent B1 prepared in Example 1 of the present invention;

[0034] Figure 4 This is a graph showing the surface tension of the aqueous solution of the amphiphilic monomer A1 prepared in Example 1 of the present invention as a function of concentration;

[0035] Figure 5 This is a hydrogen nuclear magnetic resonance spectrum of the reaction solution before and after polymerization of the monomer prepared in Example 1 of the present invention;

[0036] Figure 6 The infrared spectra of the amphiphilic monomer A1 prepared in Example 1 of the present invention before and after polymerization;

[0037] Figure 7 This is a scanning electron microscope image of the polymer solution after dialysis of microemulsion polymerization in Example 1 of the present invention;

[0038] Figure 8 This is a transmission electron microscope image of the polymer solution after dialysis of microemulsion polymerization in Example 1 of the present invention;

[0039] Fig. 9 The atomic force microscope image a of the polymer solution after dialysis of microemulsion polymerization in Example 1 of the present invention and the Origin-treated cross-sectional analysis images b and c;

[0040] Fig.10 This is a simulation diagram of the amphiphilic monomer A1 in Example 1 of the present invention in the lowest energy state by Chem3D;

[0041] Fig.11 This is a scanning electron microscope image of the polymer solution after dialysis of emulsion polymerization in Comparative Example 1 of the present invention;

[0042] Fig.12 This is a transmission electron microscope image of the polymer solution after dialysis of emulsion polymerization in Comparative Example 1 of the present invention;

[0043] Fig.13 This is a transmission electron microscopy image of the polymer solution after dialysis of microemulsion polymerization in Example 2 of the present invention;

[0044] Fig.14 This is the hydrogen nuclear magnetic resonance spectrum of the diene amphiphilic crosslinking agent B2 prepared in Example 3 of the present invention;

[0045] Fig.15 This is a transmission electron micrograph of the polymer solution after dialysis of microemulsion polymerization in Example 3 of the present invention. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] Unless otherwise specified, the test materials and reagents used in the following examples can be obtained from commercial sources.

[0048] If no specific techniques or conditions are specified in the examples, they can be carried out according to the techniques or conditions described in the literature in the art or according to the product instructions.

[0049] Example 1

[0050] A method for preparing single-layer polymer hollow spheres in one step, specifically comprising the following steps:

[0051] 1. The preparation method of the amphiphilic monomer A1 specifically comprises the following two steps:

[0052] (1) Synthesis of intermediate: 4-aminobenzoic acid (3.0 g, 21.9 mmol) was dissolved in ethanol (70 mL), placed in an ice bath at 0°C, sodium triacetoxyborohydride (6.95 g, 32.8 mmol) and dodecanal (4.9 mL, 21.9 mmol) were added to the solution, the ice bath was removed after 1 hour, and the reaction was continued at room temperature for 12 hours. After the reaction was completed, dilute hydrochloric acid solution was added for acidification, the precipitated solid was collected by filtration, washed with water, recrystallized with ethanol, filtered, and dried to obtain a white solid. Yield: 88%. Figure 1 As shown, the intermediate 4-dodecylaminobenzoic acid was characterized by hydrogen nuclear magnetic resonance spectroscopy.

[0053] The synthetic reaction formula of the intermediate is as follows:

[0054]

[0055] (2) Synthesis of A1: Weigh 4-dodecylaminobenzoic acid (1.5262 g, 5.0 mmol), add N-methylpyrrolidone (10 mL) to dissolve to obtain a reaction solution, place in an ice bath at 0°C, drop a mixture of acryloyl chloride (610 μL, 7.5 mmol) and N-methylpyrrolidone (5 mL) into the reaction solution, remove the ice bath after 1 hour, and react at room temperature for 12 hours. Add ice water, a precipitate will be precipitated, filter it, and obtain a light yellow crude product. Dissolve the crude product in ethanol, drop 2 times the volume of ethanol in water, precipitate a white precipitate, repeat 3 times, filter and dry to obtain a white product. Yield: 70%. Figure 2 As shown, the amphiphilic monomer A1 was characterized by hydrogen nuclear magnetic resonance spectroscopy.

[0056] The synthetic reaction formula is as follows:

[0057]

[0058] 2. The preparation method of the diene amphiphilic crosslinking agent B1 specifically comprises the following steps:

[0059] Add 3,5-diaminobenzoic acid (0.4425g, 2.9mmol) and ethyl acetate (35mL) to a 250mL pear-shaped bottle, then add potassium carbonate (8.0162g, 58.0mmol) aqueous solution (35mL), stir at 0℃ for 20 minutes, then add acryloyl chloride (0.95mL, 11.6mmol), and after the addition is complete, warm to room temperature to react for 2 hours. After the reaction is completed, remove the organic layer, adjust the pH of the mixed system to 4 with dilute hydrochloric acid, and precipitate. Extract the solid product with ethyl acetate, dry the organic phase with magnesium sulfate, filter and spin dry the obtained solid, rinse with deionized water, and then dry in an oven to obtain a gray-purple solid with a yield of 92%. Figure 3As shown, B1 was characterized by H NMR spectroscopy.

[0060] The synthetic reaction formula of diene amphiphilic crosslinking agent B1 is as follows:

[0061]

[0062] 3. Critical micelle concentration determination: The surface tension of surfactant monomer A1 was measured by the built-in pendant drop method using a KRUSS DSA25 standard contact angle meter. Figure 4 As shown in the figure, the surface tension of the liquid decreases significantly with the increase of surfactant monomer concentration. A turning point occurs at a concentration of 0.41239 g / L, which is the critical micelle concentration (CMC) of A1. When the CMC is reached, the surfactant molecules will associate to form micelles in the solvent, which provides a basis for the selection of the subsequent polymerization concentration.

[0063] 4. Microemulsion polymerization: Weigh the amphiphilic monomer A1 (0.5 g, 1.3918 mmol) and the diene amphiphilic crosslinker B1 (0.0036 g, 0.01398 mmol) and add them to water (16 g), add tetramethylguanidine (176 μL, 1.4058 mmol), stir and heat to 65°C to completely dissolve. Frozen vacuum and nitrogen gas were filled, and then weighed toluene (0.3 g, 3.2559 mmol) was added drop by drop to form a translucent microemulsion, and the photoinitiator phenyl (2,4,6-trimethylbenzoyl) phosphate sodium salt was added. (0.0021g, 0.0069mmol) to obtain a reaction solution, which was irradiated for 10 minutes under stirring conditions at a speed of 500r / min. After polymerization, the polymer solution was transferred to a dialysis bag with a molecular weight cutoff of 8000 and dialyzed for one week. The dialysis solvent was a mixed solution of ethanol: water = 1:5 (volume ratio). The solvent was changed 5 times a day to remove the unreacted monomers and toluene in the polymer solution.

[0064] When the surfactant concentration is greater than CMC=0.41239mg / mL, micelles will be assembled in the solution. In conventional microemulsion polymerization systems, surfactants play a role in reducing surface tension and stabilizing emulsion droplets. Therefore, the formation of microemulsions often requires a large amount of surfactants. However, in this system, in addition to the above two functions, surfactants can also act as monomers because they have olefin double bonds and can become carbon sources through free radical polymerization reactions. However, a large amount of surfactants may produce chemical gels during the polymerization process. The optimal concentration of monomer A1 is 31.25mg / mL, which is much greater than CMC because a large amount of surfactants can stabilize droplets and load more organic solvents. However, when it is greater than 35mg / mL, gels will be produced during the polymerization process. The amount of crosslinker B1 used is 1% mole fraction of A1 for polymerization. After polymerization, the polymerization solution in the reaction bottle is directly taken in D2O for nuclear magnetic hydrogen spectrum characterization, such as Figure 5 , a is the NMR hydrogen spectrum of the reaction solution before polymerization, b is the NMR hydrogen spectrum of the reaction solution after polymerization. Comparing the double bond peaks at 5.5ppm, 5.9ppm and 6.1ppm before and after polymerization, they have completely disappeared, indicating that the monomers are completely polymerized. In addition, Figure 6 3066cm in infrared spectrum -1 =CH stretching vibration peaks and 959, 973 cm -1 The disappearance of the C=C stretching vibration peak also proves the success of the polymerization. The morphology of the polymer solution after dialysis was characterized by scanning electron microscopy (SEM). Figure 7 It can be seen that the polymer obtained by microemulsion polymerization has a spherical outline, is about 300nm in size, and is evenly spread on the silicon wafer. Transmission electron microscopy (TEM) Figure 8 , and the hollow particles of uniform size were also observed to be arranged continuously. Fig. 9 a Flat round nanoparticles can also be observed, and AFM further confirms the hollow structure of the sphere and the single-layer polymer structure. The cross-sectional analysis processed by Origin shows that Fig. 9 b and 9c, the height of the sphere is about 3.6 nm, and the thickness of the amphiphilic monomer A1 molecule simulated by Chem3D in the lowest energy state is about 1.8 nm. Fig.10 , so the AFM data is about the thickness of two monolayers, which illustrates the flexibility of the monolayer polymer and the collapse of the hollow spheres after the organic solvent molecules are removed, which strongly proves the success of the one-step synthesis of monolayer polymer hollow spheres.

[0065] Comparative Example 1

[0066] Emulsion polymerization: The amphiphilic monomer A1 (0.5 g, 1.3918 mmol) and the diene amphiphilic crosslinking agent B1 (0.0036 g, 0.01398 mmol) in Example 1 were weighed and added to water (16 g), and tetramethylguanidine (176 μL, 1.4058 mmol) was added, and stirred and heated to 65°C for complete dissolution. The mixture was refrigerated and vacuumed, and nitrogen was filled. Then, the weighed toluene (4 g, 43.4122 mmol) was added dropwise to form an emulsion, and a photoinitiator, phenyl (2,4,6-trimethylbenzoyl) phosphate sodium salt (0.0021 g, 0.0069 mmol), was added to obtain a reaction solution, which was irradiated for 10 minutes under stirring conditions at a speed of 500 r / min. After polymerization, the polymer solution was transferred to a dialysis bag with a molecular weight cutoff of 8000 and dialyzed for one week. The dialysis solvent was a mixture of ethanol and water = 1:5 (volume ratio). The solvent was changed 5 times a day to remove unreacted monomers and toluene in the polymer solution.

[0067] Compared with Example 1, the increase in the amount of organic solvent in the comparative example formed an opaque emulsion. SEM Fig.11 It can be observed that the nanoparticles have uneven size distribution and a three-dimensional appearance, which is in sharp contrast to the nanoparticles in Example 1 that are flat and evenly arranged on the silicon wafer. TEM Fig.12 It can be observed that there is a clear contrast between the inside and outside of the sphere, indicating that the nanoparticles formed by emulsion polymerization are hollow structures, but unlike microemulsion polymerization, single-layer hollow spheres are not obtained. This is because the amount of organic solvent is too much, and some surfactant molecules are dissolved in the organic phase, forming multi-layer hollow spheres after polymerization, which also makes the sphere wall stronger. Even if the organic phase is completely removed, it will not collapse into a flat structure, but will be full of three-dimensional sense. This also shows that microemulsion polymerization is an effective method to obtain hollow spheres with uniform particle size and single-layer structure.

[0068] Example 2

[0069] A method for preparing single-layer polymer hollow spheres in one step, specifically comprising the following steps:

[0070] Microemulsion polymerization: The amphiphilic monomer A1 (0.3 g, 0.8351 mmol) and the diene amphiphilic crosslinking agent B1 (0.0022 g, 0.0084 mmol) in Example 1 were weighed and added to water (10 g), and tetramethylguanidine (106 μL, 0.8435 mmol) was added, and stirred and heated to 65°C for complete dissolution. The mixture was refrigerated and vacuumed, and nitrogen was filled. Then, the weighed toluene (0.2 g, 2.1706 mmol) was added dropwise to form a translucent microemulsion. Initiators potassium persulfate (0.0113 g, 0.0418 mmol) and sodium thiosulfate pentahydrate (0.0086 g, 0.0348 mmol) were added, and the mixture was polymerized at 40°C and a speed of 500 r / min for 12 hours. After polymerization, the polymer solution was transferred to a dialysis bag with a molecular weight cutoff of 8000 and dialyzed for one week. The dialysis solvent was a mixture of ethanol and water = 1:5 (volume ratio). The solvent was changed 5 times a day to remove the unreacted monomers and toluene in the polymer solution. The dialyzed polymer solution was characterized by TEM, as shown in Fig.13 As shown, hollow spheres with a particle size of about 200 nm can be observed.

[0071] Example 3

[0072] A method for preparing single-layer polymer hollow spheres in one step, specifically comprising the following steps:

[0073] The preparation method of the diene amphiphilic crosslinking agent B2 specifically comprises the following steps:

[0074] Weigh 3,5-dihydroxybenzoic acid (3.08g, 20.0mmol) and add it to a 250mL pear-shaped bottle, then add an aqueous solution (100mL) containing 2.35g of sodium hydroxide, and deoxygenate for 30 minutes under dry nitrogen bubbling. After stirring at 5°C for 20 minutes, add acryloyl chloride (6.5mL, 80.0mmol) dropwise, and after the addition is complete, warm to room temperature and react for 6 hours. After the reaction is completed, acidify with dilute hydrochloric acid to pH = 4, produce a precipitate, filter and rinse with deionized water. Dry in an oven to obtain a white solid. Yield: 92%. Fig.14 As shown, B2 was characterized by H NMR spectroscopy.

[0075] The synthetic reaction formula of diene amphiphilic crosslinking agent B2 is as follows:

[0076]

[0077] Microemulsion polymerization: The amphiphilic monomer A1 (0.25 g, 0.6958 mmol) and diene amphiphilic crosslinker B2 (0.0072 g, 0.02747 mmol) in Example 1 were weighed and added to water (8 g), and tetramethylguanidine (91 μL, 0.7233 mmol) was added, and stirred and heated to 65°C for complete dissolution. The mixture was refrigerated and vacuumed and filled with nitrogen, and then weighed toluene (0.15 g, 1.6279 mmol) was added dropwise to form a translucent microemulsion, and an initiator potassium persulfate (0.0019 g, 0.0072 mmol) was added, and the temperature was raised to 70°C, and the mixture was polymerized for 12 hours under stirring conditions at a speed of 500 r / min. After polymerization, the polymer solution was placed in an ice water bath to quench, and then the solution was poured into a dialysis bag with a molecular weight cutoff of 8000 and dialyzed for one week. The dialysis solvent was a mixture of ethanol and water = 1:5 (volume ratio). The solvent was changed 5 times a day to remove the unreacted monomers and toluene in the polymer solution. The dialyzed polymer solution was characterized by TEM, as shown in Fig.15 shown.

[0078] Example 4

[0079] A method for preparing single-layer polymer hollow spheres in one step, specifically comprising the following steps:

[0080] Preparation method of amphiphilic monomer A2:

[0081] First, 4-dodecylaminobenzoic acid was synthesized according to the method in Example 1, and 1.5262 g (5.0 mmol) was added to N-methylpyrrolidone (10 mL) to dissolve the obtained reaction solution, which was placed in an ice bath at 0°C. A mixture of methacryloyl chloride (775 μL, 8.0 mmol) and N-methylpyrrolidone (5 mL) was dripped into the reaction solution. After 1 hour, the ice bath was removed and the mixture was reacted at room temperature for 12 hours. Ice water was added, and a precipitate was precipitated. The mixture was filtered to obtain a pale yellow crude product. The crude product was dissolved in ethanol, and water with a volume of 2 times that of ethanol was dripped in to precipitate a white precipitate. The mixture was repeated 3 times, and the white product was collected by filtration and drying. Yield: 79%. The synthetic reaction formula is shown below:

[0082]

[0083] Miniemulsion polymerization: Replace A1 in Example 1 with an equal molar amount of A2, and keep the rest unchanged.

[0084] Example 5

[0085] A method for preparing single-layer polymer hollow spheres in one step, specifically comprising the following steps:

[0086] The preparation method of the amphiphilic monomer A3 specifically comprises the following two steps:

[0087] (1) Synthesis of intermediate: 4-aminobenzoic acid (3.0 g, 21.9 mmol) was dissolved in ethanol (70 mL), placed in an ice bath at 0°C, sodium triacetoxyborohydride (6.95 g, 32.8 mmol) and 1-decanal (4.12 mL, 21.9 mmol) were added to the solution, the ice bath was removed after 1 hour, and the reaction was continued at room temperature for 12 hours. After the reaction was completed, dilute hydrochloric acid solution was added for acidification, the precipitated solid was collected by filtration, washed with water, recrystallized with ethanol, filtered, and dried to obtain a white solid. Yield: 82%. The synthesis reaction formula of the intermediate is shown below:

[0088]

[0089] (2) Synthesis of A3: Weigh the above product (2.7720 g, 10.0 mmol) and add N-methylpyrrolidone (20 mL) to dissolve to obtain a reaction solution, place it in an ice bath at 0°C, drop a mixture of acryloyl chloride (1.22 mL, 15.0 mmol) and N-methylpyrrolidone (8 mL) into the reaction solution, remove the ice bath after 1 hour, and react at room temperature for 12 hours. Add ice water, a precipitate is precipitated, and it is filtered to obtain a pale yellow crude product. The crude product is dissolved in ethanol, and water with a volume of 2 times the volume of ethanol is added to precipitate a white precipitate. Repeat 3 times, filter and dry to collect a white product. Yield: 69%. The reaction formula is as follows:

[0090]

[0091] Miniemulsion polymerization: Replace A1 in Example 1 with an equal molar amount of A3, and keep the rest unchanged.

[0092] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing single-layer polymer hollow spheres in one step, characterized in that: The following steps are involved: The amphiphilic monomer A, the diene amphiphilic crosslinking agent B, water and alkali are mixed and dissolved to form micelles, after deoxygenation and nitrogen filling, an organic solvent is added and stirred to form swollen micelles, an initiator is added to carry out microemulsion polymerization, and after the reaction is completed, purification is carried out to obtain the single-layer polymer hollow spheres; The general structural formulas of the amphiphilic monomer A and the diene amphiphilic crosslinking agent B are shown in Formula 1 and Formula 2, respectively: Where R1=-(CH2) n -CH3 n=9 or 11 or 13; The diene amphiphilic crosslinking agent B is 1-5% of the molar amount of the amphiphilic monomer A; and the amount of the organic solvent is the maximum capacity increase of the micelle at this concentration.

2. The method for preparing single-layer polymer hollow spheres in one step according to claim 1, characterized in that: The structural formula of the amphiphilic monomer A is One of the following; the structural formula of the diene amphiphilic crosslinking agent B is 3. The method for preparing single-layer polymer hollow spheres in one step according to claim 1, characterized in that: In the micelles formed after dissolution, the concentration of the amphiphilic monomer A is 20 mg / mL to 35 mg / mL.

4. The method for preparing single-layer polymer hollow spheres in one step according to claim 1, characterized in that: In the micelle formed after dissolution, the concentration of the amphiphilic monomer A is 31.25 mg / mL, and the diolefin amphiphilic crosslinking agent B is 1% of the molar amount of the amphiphilic monomer A.

5. The method for preparing single-layer polymer hollow spheres in one step according to claim 1, characterized in that: The base is one of 1,1,3,3-tetramethylguanidine, triethylamine, sodium hydroxide and potassium hydroxide.

6. The method for preparing single-layer polymer hollow spheres in one step according to claim 1, characterized in that: The organic solvent is one of toluene, n-hexane, n-heptane, n-octane, dodecane and hexadecane, or a mixture of more than one of the above.

7. The method for preparing single-layer polymer hollow spheres in one step according to claim 1, characterized in that: The initiator includes one of a photoinitiator, a thermal initiator, and a redox initiation system.

8. The method for preparing single-layer polymer hollow spheres in one step according to claim 1, characterized in that: The pH of the dissolved micelles was 8.

9. The method for preparing single-layer polymer hollow spheres in one step according to claim 2, characterized in that: The preparation method of the amphiphilic monomer A comprises the following steps: S1, dissolving 4-aminobenzoic acid in ethanol, adding sodium triacetoxyborohydride, dodecanal or 1-decanal to react at 0°C, and then continuing the reaction at room temperature. After the reaction is completed, post-treatment is performed to obtain a solid product; S2, mixing and dissolving the solid product in S1 with N-methylpyrrolidone, placing at 0°C, adding a mixture of acryloyl chloride or methacryloyl chloride and N-methylpyrrolidone to react, then continuing the reaction at room temperature, adding ice water and post-treating to obtain the amphiphilic monomer A.

10. A single-layer polymer hollow sphere, characterized in that: The hollow single-layer polymer spheres are prepared by the one-step method for preparing the hollow single-layer polymer spheres as described in any one of claims 1 to 9.

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