Monodisperse submicron polyurethane microsphere as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of high polymer materials, and discloses monodisperse submicron polyurethane microspheres as well as a preparation method and application thereof. According to the method, a mixed solvent of an organic solvent and water is used as a good solvent, polyurethane prepared from raw materials including polyisocyanate and dihydric alcohol or polyhydric alcohol containing carboxylic acid, sulfonic acid and the like is dissolved in the good solvent, then water is used as a poor solvent, the flow speed of the water is controlled, the water is added into the polyurethane, and through the interaction of the polyurethane and the good solvent / poor solvent, the polyurethane is prepared. The preparation method comprises the following steps: carrying out nano precipitation at room temperature and under stirring conditions in a short time to obtain a product, namely, submicron monodisperse polyurethane spheres, and then carrying out multiple times of centrifugal separation, washing and drying on the product to obtain the monodisperse submicron polyurethane microspheres. Moreover, the polyurethane photonic crystal with bright structural color can be assembled by methods such as centrifugation and vertical deposition.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and particularly relates to monodisperse submicron polyurethane microspheres and a preparation method and application thereof. Background Art

[0002] Polyurethane has a wide range of applications in the fields of biomedicine, daily furniture, etc. due to its good biocompatibility, physical and mechanical properties, etc., but these applications are relatively macroscopic. In the microscopic field, the application of polyurethane microspheres is relatively small, mainly because the complexity of the polyurethane structure makes it difficult to balance between the size and monodispersity of the particle size. Therefore, polyurethane microspheres with submicron particle size and good monodispersity have high application value in the fields of chromatographic analysis, standard measurement, photonic crystals, liquid crystal displays, dyes, and controlled drug release. Traditional methods for preparing polyurethane microspheres include emulsion polymerization, interfacial polymerization, precipitation polymerization, etc. The first two methods are to first prepare polyurethane by reacting isocyanate and alcohol hydroxyl groups, and then prepare polyurethane microspheres by self-emulsification using high speed or ultrasound, while the latter two methods are to prepare polyurethane microspheres by using the change in solubility of the reactant or product in the solvent. CN179192A discloses a method for preparing cross-linked polyurethane microspheres, that is, first synthesizing an isocyanate-terminated prepolymer, then pouring the prepolymer into an aqueous dispersion containing a surfactant, and cross-linking and curing to obtain the product. CN105418872A uses a dispersion polymerization method to prepare cross-linked polyurethane microspheres containing functional groups in one step. CN102643402 discloses a method of directly dispersing isocyanate monomers into a mixed solution of water and acetone to finally obtain polyurea microspheres with good monodispersity. CN108219110A uses a mixed solvent of two mutually soluble organic solvents as a reaction medium, diisocyanate or polyisocyanate and diol or polyol as reaction monomers, and performs precipitation polymerization at room temperature and static conditions to prepare monodisperse micron-sized polyurethane microspheres. Chemical Engineering Journal, 2012, 213 (12): 214-217. A method for generating monodisperse polyurea microspheres by reacting IPDI with water is introduced. Polymer, 2016, 83: 214-222. A solvent thermal method is used to obtain highly cross-linked monodisperse poly (ethylene glycol-dimethacrylate) microspheres. However, the polyurethane microspheres prepared in the above patents and articles have the problem that the particle size and monodispersity cannot be satisfied at the same time. The polyurethane microspheres prepared by emulsion polymerization and microemulsion polymerization can reach hundreds or even tens of nanometers, but the monodispersity is often very poor. The polyurethane microspheres prepared by interfacial polymerization and precipitation polymerization can achieve good monodispersity, but the particle size is generally a few microns or even more than ten microns. Summary of the invention

[0003] In order to overcome the shortcomings and deficiencies in the above-mentioned prior art, the primary purpose of the present invention is to provide a method for preparing monodisperse submicron polyurethane microspheres; the method adopts a one-step reaction to prepare polyurethane, utilizes the high reaction activity of isocyanate and hydroxyl, does not require the use of a catalyst, and avoids the side reaction of isocyanate monomer and water, and then utilizes a solvent / anti-solvent method to prepare submicron monodisperse polyurethane microspheres, the microspheres have good stability, small product particle size and good monodispersity, and are easy to industrialize and mass produce.

[0004] Another object of the present invention is to provide a polyurethane having a narrow molecular weight distribution which can be prepared by the above preparation method in a relatively short time.

[0005] Another object of the present invention is to provide an application of the above-mentioned monodisperse submicron polyurethane microspheres.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] A method for preparing monodisperse submicron polyurethane microspheres comprises the following steps:

[0008] (1) preparing a diisocyanate and a diol with a carboxylic acid or sulfonic acid group into solutions respectively with a solvent, wherein the molar ratio of the diisocyanate to the diol with a carboxylic acid or sulfonic acid group is (1.0-1.5):1; dropping the diisocyanate solution into the diol solution with a carboxylic acid or sulfonic acid group under an oil bath and magnetic stirring, and reacting at 30-60° C. for 4-6 hours after the diisocyanate solution is added, and after the reaction is completed, pouring the product into a polytetrafluoroethylene mold or a glass culture dish, and drying in an oven at 80° C. for 48 hours to remove the solvent, thereby obtaining a polyurethane powder;

[0009] (2) adding the polyurethane powder obtained in step (1) to a mixed solvent of acetone and water, and completely dissolving the polyurethane powder under magnetic stirring to obtain a polyurethane solution; injecting deionized water dropwise into the polyurethane solution using a syringe pump while controlling the flow rate, and after the deionized water is added dropwise, continuing to stir for 10 minutes to obtain a polyurethane microsphere emulsion;

[0010] (3) The polyurethane microsphere emulsion obtained in step (2) is first evaporated by a rotary evaporator to remove acetone, and then the remaining emulsion is centrifuged to remove the supernatant, and the centrifuged product is washed with deionized water, and the above centrifugation and washing operations are repeated 2 to 3 times, and then the centrifuged product is dispersed in water again, freeze-dried or spray-dried to remove water, to obtain monodisperse submicron polyurethane microspheres.

[0011] The diisocyanate described in step (1) is toluene-2,4-diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate or meta-xylylene diisocyanate.

[0012] The diol with a carboxylic acid or sulfonic acid group in step (1) is 2,2-dihydroxymethylpropionic acid, 2,2-dihydroxymethylbutyric acid, dihydroxybenzoic acid, N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid or N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid sodium salt.

[0013] The solvent in step (1) is acetone, tetrahydrofuran, N,N-dimethylformamide, dimethyl sulfoxide, ethyl acetate, toluene or dioxane.

[0014] The time required for the polyurethane powder to be completely dissolved under the magnetic stirring in step (2) is 10 minutes; the volume ratio of acetone to water in the acetone and water mixed solvent is 8:2; the solid-liquid ratio of the polyurethane powder to the mixed solvent is 2 mg:1 ml to 4 mg:1 ml; and the dropping speed is 1.25-11 ml / min.

[0015] The centrifugation in step (3) is carried out at a speed of 5000-13000 r / min for 10-30 minutes.

[0016] The invention discloses monodisperse submicron polyurethane microspheres prepared by the above preparation method, wherein the particle size of the monodisperse submicron polyurethane microspheres is 100nm-1μm, and the PDI reaches 0.005.

[0017] The above-mentioned monodisperse submicron polyurethane microspheres are used in the fields of chromatography analysis, drug controlled release, or photonic crystals.

[0018] Compared with the prior art, the present invention has the following advantages and effects:

[0019] (1) The present invention is a two-step method for preparing submicron monodisperse polyurethane microspheres, which overcomes the existing problem of difficult balance between particle size and monodispersity. Compared with the existing polyurethane microspheres with small particle size but poor monodispersity and good monodispersity but large particle size, the polyurethane microspheres prepared by the method of the present invention can have good monodispersity while maintaining a small particle size, and can be carried out at room temperature. The experiment is simple, economical and practical, and is conducive to the large-scale production of submicron monodisperse polyurethane microspheres.

[0020] (2) In the reaction system prepared by the present invention, no catalyst, emulsifier, stabilizer or other auxiliary agents are required, and only the reaction monomers need to be dissolved in the solution. Therefore, the post-processing steps are simple, the operation is convenient, and the product cost is saved.

[0021] (3) In the preparation method of the present invention, the preparation of microspheres is carried out in two steps, and the preparation of polyurethane and the synthesis of microspheres are carried out separately, thereby avoiding many side reactions and improving the utilization rate of monomers.

[0022] (4) The present invention can prepare monodisperse polyurethane microspheres in a relatively short time, greatly saving time, and can maintain good monodispersity while preparing quickly;

[0023] (5) When the method of the present invention is used to prepare monodisperse microspheres, the monomer conversion rate is high and the microsphere yield can reach nearly 100%. Compared with the traditional preparation method, the yield is greatly improved. At the same time, this method will not or rarely produce side reactions or incomplete reactions.

[0024] (6) The microspheres prepared by the method of the present invention have a clean surface and uniform particle size. Through testing and characterization, the PDI of the microspheres can reach 0.005. Therefore, the polyurethane microspheres prepared by this method can be used in the fields of preparing photonic crystals and drug release. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is the infrared spectrum of the polyurethane microspheres prepared by the method of the present invention in Example 1.

[0026] Figure 2 This is a low-temperature differential scanning calorimetry diagram of the polyurethane microspheres prepared by the method of the present invention in Example 1.

[0027] Figure 3 This is a scanning electron microscope image of the polyurethane microspheres in Example 1.

[0028] Figure 4 This is a scanning electron microscope image of the polyurethane microspheres in Example 2.

[0029] Figure 5 This is a scanning electron microscope image of the polyurethane microspheres in Example 3.

[0030] Figure 6 This is a scanning electron microscope image of the polyurethane microspheres in Example 4.

[0031] Figure 7 This is an optical photograph of the photonic crystal assembled from the polyurethane microspheres in Example 4.

[0032] Figure 8 This is a scanning electron microscope image of the polyurethane microspheres in Example 5.

[0033] Fig. 9 This is a scanning electron microscope image of the polyurethane microspheres in Example 6.

[0034] Fig.10 This is a scanning electron microscope image of the polyurethane microspheres in Example 7.

[0035] Fig.11 This is a scanning electron microscope image of the polyurethane microspheres in Example 8.

[0036] Fig.12 This is a scanning electron microscope image of the polyurethane microspheres in Example 9.

[0037] Fig.13 This is a scanning electron microscope image of the polyurethane microspheres in Example 10. DETAILED DESCRIPTION

[0038] The present invention is further described below with reference to specific embodiments, but they should not be construed as limiting the present invention.

[0039] The method for preparing monodisperse micron-sized polyurethane microspheres provided by the present invention comprises the following steps:

[0040] (1) preparing a diisocyanate and a diol with a carboxylic acid or sulfonic acid group into solutions respectively with a solvent, wherein the molar ratio of the diisocyanate to the diol with a carboxylic acid or sulfonic acid group is (1.0-1.5):1; dropping the diisocyanate solution into the diol solution with a carboxylic acid or sulfonic acid group under an oil bath and magnetic stirring, and reacting at 30-60° C. for 4-6 hours after the diisocyanate solution is added, and after the reaction is completed, pouring the product into a polytetrafluoroethylene mold or a glass culture dish, and drying in an oven at 80° C. for 48 hours to remove the solvent, thereby obtaining a polyurethane powder;

[0041] (2) adding the polyurethane powder obtained in step (1) to a mixed solvent of acetone and water (the volume ratio of acetone to water is 8:2), and completely dissolving the polyurethane powder under magnetic stirring to obtain a polyurethane solution; injecting deionized water into the polyurethane solution by a syringe pump while controlling the flow rate, and continuing to stir for 10 minutes after the deionized water is added, to obtain a polyurethane microsphere emulsion. The whole process can be quickly completed within 20 minutes;

[0042] (3) The polyurethane microsphere emulsion obtained in step (2) is first evaporated by a rotary evaporator to remove acetone, and then the remaining emulsion is centrifuged to remove the supernatant, and the centrifuged product is washed with deionized water, and the above centrifugation and washing operations are repeated 2 to 3 times. Thereafter, the centrifuged product is dispersed in water again, and freeze-dried or spray-dried to remove water to obtain monodisperse submicron polyurethane microspheres. The obtained polyurethane microspheres can be dispersed in water again, and polyurethane photonic crystals with bright structural colors can be prepared by gravity, centrifugal force, etc.

[0043] In the above preparation method, the diisocyanate is toluene-2,4-diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate or meta-xylylene diisocyanate.

[0044] In the above preparation method, the diol with a carboxylic acid or sulfonic acid group is 2,2-dihydroxymethylpropionic acid, 2,2-dihydroxymethylbutyric acid, dihydroxybenzoic acid, N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid or N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid sodium salt.

[0045] In the above preparation method, the solvent is acetone, tetrahydrofuran, N,N-dimethylformamide, dimethyl sulfoxide, ethyl acetate, toluene or dioxane.

[0046] In the above preparation method, the centrifugation in step (3) is performed at a speed of 5000-13000 r / min for 10-30 minutes;

[0047] In the above preparation method, the freeze-drying in step (3) is specifically to redisperse the polyurethane microspheres in water, freeze them at 0°C, and then remove the moisture using a freeze dryer to obtain polyurethane microsphere powder, or to directly remove the moisture from the microsphere suspension redispersed in water using a spray drying device.

[0048] The polyurethane microspheres prepared by the method have a particle size between 100 nm and 1 μm, have good monodispersity, and the PDI of the microspheres can reach 0.005. The particle size can be controlled according to reaction conditions such as polymer concentration, solvent ratio, and deionized water droplet acceleration rate.

[0049] The method has a yield of 80%-100% for preparing polyurethane microspheres, a high polyurethane utilization rate, and the microspheres can maintain good monodispersity while having a small particle size, and the entire process takes a short time.

[0050] The following is an example of the preparation method of the present invention:

[0051] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0052] Example 1

[0053] At 40°C, 0.015 mol (about 2.67 g) of toluene-2,4-diisocyanate (TDI) is dissolved in 20 ml of N,N-dimethylformamide to obtain the first reactant, and 0.01 mol (about 1.37 g) of 2,2-dihydroxymethyl propionic acid is dissolved in 20 ml of N,N-dimethylformamide to obtain the second reactant. The second reactant is added to a three-necked flask with a magnetic stirrer, the magnetic stirring of the oil bath is turned on, and the first reactant is slowly added to the first reactant with a Pasteur pipette. After the second reactant is added, a nitrogen balloon is installed in the three-necked flask to ensure a nitrogen atmosphere in the flask. After reacting for 4 to 6 hours, the liquid in the three-necked flask is poured into a polytetrafluoroethylene mold or a glass culture dish, and then placed in a vacuum oven at 80°C to remove N,N-dimethylformamide, and then the obtained solid polyurethane is ground into powder with a mortar, that is, polyurethane powder, for standby use.

[0054] The polyurethane powder obtained above was weighed with an analytical balance and dissolved in acetone and water (v 丙酮 :v 水 =8:2) in a mixed solvent (polyurethane powder: mixed solvent liquid ratio 4.0 mg / ml), and a magnetic stirrer is added to the beaker, the magnetic stirring is turned on, and the polyurethane powder is stirred for 10 minutes. After the polyurethane powder is completely dissolved, 20-40 ml of deionized water is injected into the beaker at a dropping speed of 1.25 ml / min using a syringe pump. During the injection process, it can be found that when a certain amount is reached, the liquid in the beaker begins to become turbid. After the deionized water is added, stirring is continued for 10 minutes to stabilize the polyurethane microspheres.

[0055] Subsequently, the acetone was removed by a rotary evaporator, and then a high-speed centrifuge was used to centrifuge at 8000 rpm for 30 minutes to remove the supernatant. The centrifuged product was then washed with deionized water. The above centrifugation and washing operations were repeated 3 times. After that, the centrifuged product was redispersed in water, and a freeze dryer was used to remove water to reduce the water content therein, thereby obtaining a monodisperse submicron polyurethane microsphere solid powder.

[0056] The yield of polyurethane microspheres obtained in this example is 91%, the average particle size is 495.4nm, the PDI of the particle size is 0.005, and the scanning electron microscope image is as follows Figure 3 Its infrared spectrum is as follows Figure 1 From the infrared spectrum, we can see that at 3344.5cm -1 The stretching vibration peak of -NH bond was found at 1700cm -1 The stretching vibration peaks of -C=O were found on the left and right sides. These two characteristic peaks indicate the successful synthesis of polyurethane. -1 The characteristic peak of -CNO at 1600cm -1The characteristic peaks of C=O stretching vibration in urea are found on the left and right, indicating that the purpose of -NCO end-capping has been achieved. Figure 2 In the DSC, it can be seen that the glass transition temperature of the polyurethane synthesized by this method can reach about 16°C, which is higher than that of conventional polyurethane.

[0057] Example 2

[0058] A certain amount of the polyurethane powder obtained in Example 1 was weighed with an analytical balance and dissolved in acetone and water (v 丙酮 :v 水 =8:2) in a mixed solvent (polyurethane: mixed solvent ratio 4.0 mg / ml), and a magnetic stirrer is added to the beaker, the magnetic stirring is turned on, and the polyurethane is stirred for 10 minutes. After the polyurethane is completely dissolved, 20 to 40 ml of deionized water is injected into the beaker with a syringe pump at a dropping speed of 4.25 ml / min. During the injection process, it can be found that when a certain amount is reached, the liquid in the beaker begins to become turbid. Wait until the deionized water is added and continue stirring for 10 minutes to stabilize the polyurethane microspheres.

[0059] Subsequently, the acetone was removed by a rotary evaporator, and then a high-speed centrifuge was used to centrifuge at 6000 rpm for 20 minutes to remove the supernatant. The centrifuged product was then washed with deionized water. The above centrifugation and washing operations were repeated 3 times. After that, the centrifuged product was dispersed in water again, and a freeze dryer was used to remove water to reduce the water content therein, thereby obtaining a monodisperse submicron polyurethane microsphere solid powder.

[0060] The yield of polyurethane microspheres obtained in this example is 91%, the average particle size is 342.8nm, the PDI of the particle size is 0.016, and the scanning electron microscope image is as follows Figure 4 .

[0061] Example 3

[0062] A certain amount of the polyurethane powder obtained in Example 1 was weighed with an analytical balance and dissolved in acetone and water (v 丙酮 :v 水 =8:2) in a mixed solvent (polyurethane: mixed solvent ratio 4.0 mg / ml), and a magnetic stirrer is added to the beaker, the magnetic stirring is turned on, and the polyurethane is stirred for 10 minutes. After the polyurethane is completely dissolved, 20 to 40 ml of deionized water is injected into the beaker with a syringe pump at a dropping speed of 6.50 ml / min. During the injection process, it can be found that when a certain amount is reached, the liquid in the beaker begins to become turbid. Wait until the deionized water is added and continue stirring for 10 minutes to stabilize the polyurethane microspheres.

[0063] Subsequently, the acetone was removed by a rotary evaporator, and then a high-speed centrifuge was used to centrifuge at 8000 rpm for 30 minutes to remove the upper clear liquid. The centrifuged product was then washed three times with deionized water, and then the lower solid material was dispersed in deionized water, and a freeze dryer was used to remove water to reduce the water content therein, thereby obtaining a monodisperse submicron polyurethane microsphere solid powder.

[0064] The yield of polyurethane microspheres obtained in this example is 91.6%, the average particle size is 315.6nm, the PDI of the particle size is 0.013, and the scanning electron microscope image is as follows Figure 5 .

[0065] Example 4

[0066] The polyurethane powder obtained in Example 1 was weighed with an analytical balance and dissolved in acetone and water (v 丙酮 :v 水 =8:2) in a mixed solvent (polyurethane: mixed solvent = 4.0 mg / ml), and a magnetic stirrer is added to the beaker, the magnetic stirring is turned on, and the polyurethane is stirred for 10 minutes. After the polyurethane is completely dissolved, 20 to 40 ml of deionized water is injected into the beaker with a syringe pump at a dropping speed of 8.75 ml / min. During the injection process, it can be found that when a certain amount is reached, the liquid in the beaker begins to become turbid. Wait until the deionized water is added and continue stirring for 10 minutes to stabilize the polyurethane microspheres.

[0067] Subsequently, the acetone was removed by a rotary evaporator, and then a high-speed centrifuge was used to centrifuge at 8000 rpm for 30 minutes to remove the supernatant. The centrifuged product was then washed with deionized water. The above centrifugation and washing operations were repeated 3 times. After that, the centrifuged product was redispersed in water, and a freeze dryer was used to remove water to reduce the water content therein, thereby obtaining a monodisperse submicron polyurethane microsphere solid powder.

[0068] The yield of polyurethane microspheres obtained in this example is 90%, the average particle size is 267.3, the PDI of the particle size is 0.008, and the scanning electron microscope image is as follows Figure 6 At the same time, the obtained submicron monodisperse polyurethane spheres can be assembled by centrifugal force to prepare polyurethane photonic crystals, and have brighter structural colors. The structural color optical photos are shown in Figure 7 .

[0069] Example 5

[0070] The polyurethane powder obtained in Example 1 was weighed with an analytical balance and dissolved in acetone and water (v 丙酮 :v 水=8:2) in a mixed solvent (polyurethane: mixed solvent = 4.0 mg / ml), and a magnetic stirrer is added to the beaker, the magnetic stirring is turned on, and the polyurethane is stirred for 10 minutes. After the polyurethane is completely dissolved, 20 to 40 ml of deionized water is injected into the beaker with a syringe pump at a dropping speed of 11.00 ml / min. During the injection process, it can be found that when a certain amount is reached, the liquid in the beaker begins to become turbid. Wait until the deionized water is added and continue stirring for 10 minutes to stabilize the polyurethane microspheres.

[0071] Subsequently, the acetone was removed by a rotary evaporator, and then a high-speed centrifuge was used for centrifugation at 10,000 rpm for 30 minutes to remove the supernatant. The centrifuged product was then washed with deionized water. The above centrifugation and washing operations were repeated 3 times. After that, the centrifuged product was redispersed in water, and a freeze dryer was used to remove water to reduce the water content therein, thereby obtaining a monodisperse submicron polyurethane microsphere solid powder.

[0072] The yield of polyurethane microspheres obtained in this example is 90%, the average particle size is 205.7nm, the PDI of the particle size is 0.005, and the scanning electron microscope image is as follows Figure 8 .

[0073] Example 6

[0074] A certain amount of the polyurethane powder obtained in Example 1 was weighed with an analytical balance and dissolved in acetone and water (v 丙酮 :v 水 =8:2) in a mixed solvent (polyurethane: mixed solvent = 2.45 mg / ml), and a magnetic stirrer is added to the beaker, the magnetic stirring is turned on, and the polyurethane is stirred for 10 minutes. After the polyurethane is completely dissolved, 20 to 40 ml of deionized water is injected into the beaker with a syringe pump at a dropping speed of 1.25 ml / min. During the injection process, it can be found that when a certain amount is reached, the liquid in the beaker begins to become turbid. Wait until the deionized water is added and continue stirring for 10 minutes to stabilize the polyurethane microspheres.

[0075] Subsequently, the acetone was removed by a rotary evaporator, and then a high-speed centrifuge was used to centrifuge at 7000 rpm for 30 minutes to remove the supernatant. The centrifuged product was then washed with deionized water. The above centrifugation and washing operations were repeated 3 times. After that, the centrifuged product was redispersed in water, and a freeze dryer was used to remove water to reduce the water content therein, thereby obtaining a monodisperse submicron polyurethane microsphere solid powder.

[0076] The yield of polyurethane microspheres obtained in this example is 91%, the average particle size is 324.5, the PDI of the particle size is 0.015, and the scanning electron microscope image is as follows Fig. 9 .

[0077] Example 7

[0078] A certain amount of the polyurethane powder obtained in Example 1 was weighed with an analytical balance and dissolved in acetone and water (v 丙酮 :v 水 =8:2) in a mixed solvent (polyurethane: mixed solvent = 2.45 mg / ml), and a magnetic stirrer is added to the beaker, the magnetic stirring is turned on, and the polyurethane is stirred for 10 minutes. After the polyurethane is completely dissolved, 20 to 40 ml of deionized water is injected into the beaker with a syringe pump at a dropping speed of 4.25 ml / min. During the injection process, it can be found that when a certain amount is reached, the liquid in the beaker begins to become turbid. Wait until the deionized water is added and continue stirring for 10 minutes to stabilize the polyurethane microspheres.

[0079] Subsequently, the acetone was removed by a rotary evaporator, and then a high-speed centrifuge was used to centrifuge at 8000 rpm for 30 minutes to remove the supernatant. The centrifuged product was then washed with deionized water. The above centrifugation and washing operations were repeated 3 times. After that, the centrifuged product was redispersed in water, and a freeze dryer was used to remove water to reduce the water content therein, thereby obtaining a monodisperse submicron polyurethane microsphere solid powder.

[0080] The yield of polyurethane microspheres obtained in this example is 93.2%, the average particle size is 254.9 nm, the PDI of the particle size is 0.005, and the scanning electron microscope image is as follows Fig.10 .

[0081] Example 8

[0082] A certain amount of the polyurethane powder obtained in Example 1 was weighed with an analytical balance and dissolved in acetone and water (v 丙酮 :v 水 =8:2) in a mixed solvent (polyurethane: mixed solvent = 2.45 mg / ml), and a magnetic stirrer is added to the beaker, the magnetic stirring is turned on, and the polyurethane is stirred for 10 minutes. After the polyurethane is completely dissolved, 20 to 40 ml of deionized water is injected into the beaker with a syringe pump at a dropping speed of 6.5 ml / min. During the injection process, it can be found that when a certain amount is reached, the liquid in the beaker begins to become turbid. Wait until the deionized water is added and continue stirring for 10 minutes to stabilize the polyurethane microspheres.

[0083] Subsequently, the acetone was removed by a rotary evaporator, and then a high-speed centrifuge was used for centrifugation at 10,000 rpm for 30 minutes to remove the supernatant. The centrifuged product was then washed with deionized water. The above centrifugation and washing operations were repeated 3 times. After that, the centrifuged product was redispersed in water, and a freeze dryer was used to remove water to reduce the water content therein, thereby obtaining a monodisperse submicron polyurethane microsphere solid powder.

[0084] The yield of polyurethane microspheres obtained in this example is 93.2%, the average particle size is 215.7 nm, the PDI of the particle size is 0.005, and the scanning electron microscope image is as follows Fig.11.

[0085] Example 9

[0086] A certain amount of the polyurethane powder obtained in Example 1 was weighed with an analytical balance and dissolved in acetone and water (v 丙酮 :v 水 =8:2) in a mixed solvent (polyurethane: mixed solvent = 2.45 mg / ml), and a magnetic stirrer is added to the beaker, the magnetic stirring is turned on, and the polyurethane is stirred for 10 minutes. After the polyurethane is completely dissolved, 20 to 40 ml of deionized water is injected into the beaker with a syringe pump at a dropping speed of 8.75 ml / min. During the injection process, it can be found that when a certain amount is reached, the liquid in the beaker begins to become turbid. Wait until the deionized water is added and continue stirring for 10 minutes to stabilize the polyurethane microspheres.

[0087] Subsequently, the acetone was removed by a rotary evaporator, and then a high-speed centrifuge was used to centrifuge for 30 minutes at 11,000 rpm to remove the supernatant. The centrifuged product was then washed with deionized water. The above centrifugation and washing operations were repeated 3 times. After that, the centrifuged product was redispersed in water, and a freeze dryer was used to remove water to reduce the water content therein, thereby obtaining a monodisperse submicron polyurethane microsphere solid powder.

[0088] The yield of polyurethane microspheres obtained in this example is 93.2%, the average particle size is 176.4 nm, the PDI of the particle size is 0.005, and the scanning electron microscope image is as follows Fig.12 .

[0089] Example 10

[0090] A certain amount of the polyurethane powder obtained in Example 1 was weighed with an analytical balance and dissolved in acetone and water (v 丙酮 :v 水 =8:2) in a mixed solvent (polyurethane: mixed solvent = 2.45 mg / ml), and a magnetic stirrer is added to the beaker, the magnetic stirring is turned on, and the polyurethane is stirred for 10 minutes. After the polyurethane is completely dissolved, 20 to 40 ml of deionized water is injected into the beaker at a dropping speed of 11 ml / min using a syringe pump. During the injection process, it can be found that when a certain amount is reached, the liquid in the beaker begins to become turbid. Wait until the deionized water is added and continue stirring for 10 minutes to stabilize the polyurethane microspheres.

[0091] Subsequently, the acetone was removed by a rotary evaporator, and then a high-speed centrifuge was used to centrifuge at 13,000 rpm for 30 minutes to remove the supernatant. The centrifuged product was then washed with deionized water. The above centrifugation and washing operations were repeated 3 times. After that, the centrifuged product was dispersed in water again, and a freeze dryer was used to remove water to reduce the water content therein, thereby obtaining a monodisperse submicron polyurethane microsphere solid powder.

[0092] The yield of polyurethane microspheres obtained in this example is 92.7%, the average particle size is 132.8 nm, the PDI of the particle size is 0.011, and the scanning electron microscope image is as follows Fig.13 .

[0093] Embodiment 11

[0094] At 50°C, 0.015 mol (about 3.4 g) of isophorone diisocyanate (IPDI) is dissolved in 20 ml of N,N-dimethylformamide to obtain the first reactant, and 0.01 mol (about 1.27 g) of 2,2-dihydroxymethyl propionic acid is dissolved in 20 ml of N,N-dimethylformamide to obtain the second reactant. The second reactant is added to a three-necked flask with a magnetic stirrer, the magnetic stirring of the oil bath is turned on, and the first reactant is slowly added to the first reactant with a Pasteur pipette. After the second reactant is added, a nitrogen balloon is installed in the three-necked flask to ensure a nitrogen atmosphere in the flask. After reacting for 4 to 6 hours, the liquid in the three-necked flask is poured into a polytetrafluoroethylene mold or a glass culture dish, and then placed in a vacuum oven at 80°C to remove N,N-dimethylformamide, and then the obtained solid polyurethane is ground into powder with a mortar for standby use.

[0095] The polyurethane powder obtained above was weighed with an analytical balance and dissolved in acetone and water (v 丙酮 :v 水 =7:3) in a mixed solvent (polyurethane: mixed solvent = 4.0 mg / ml), and a magnetic stirrer is added to the beaker, the magnetic stirring is turned on, and the polyurethane is stirred for 10 minutes. After the polyurethane is completely dissolved, 20 to 40 ml of deionized water is injected into the beaker at a dropping speed of 6.5 ml / min using a syringe pump. During the injection process, it can be found that when a certain amount is reached, the liquid in the beaker begins to become turbid. Wait until the deionized water is added and continue stirring for 10 minutes to stabilize the polyurethane microspheres.

[0096] Subsequently, the acetone was removed by a rotary evaporator, and then the supernatant was removed by a high-speed centrifuge at 8000 rpm for 30 minutes, and the centrifuged product was washed with deionized water. The above centrifugation and washing operations were repeated 3 times, and then the centrifuged product was dispersed in water again, and the water was removed by a freeze dryer to obtain a monodisperse submicron polyurethane microsphere solid powder.

[0097] Example 12

[0098] At 60°C, 0.015 mol (about 4.01 g) of dicyclohexylmethane-4,4'-diisocyanate (HMDI) is dissolved in 20 ml of N,N-dimethylformamide to obtain the first reactant, and 0.01 mol (about 1.27 g) of 2,2-dihydroxymethylpropionic acid is dissolved in 20 ml of N,N-dimethylformamide to obtain the second reactant. The second reactant is added to a three-necked flask with a magnetic stirrer, the magnetic stirring of the oil bath is turned on, and the first reactant is slowly added to the first reactant with a Pasteur pipette. After the second reactant is added, a nitrogen balloon is installed in the three-necked flask to ensure a nitrogen atmosphere in the flask. After reacting for 4 to 6 hours, the liquid in the three-necked flask is poured into a polytetrafluoroethylene mold or a glass culture dish, and then placed in a vacuum oven at 80°C to remove N,N-dimethylformamide, and then the obtained solid polyurethane is ground into powder with a mortar for standby use.

[0099] The polyurethane powder obtained above was weighed with an analytical balance and dissolved in acetone and water (v 丙酮 :v 水 =8:2) in a mixed solvent (polyurethane: mixed solvent = 2.0 mg / ml), and a magnetic stirrer is added to the beaker, the magnetic stirring is turned on, and the polyurethane is stirred for 10 minutes. After the polyurethane is completely dissolved, 20 to 40 ml of deionized water is injected into the beaker with a syringe pump at a dropping speed of 8.75 ml / min. During the injection process, it can be found that when a certain amount is reached, the liquid in the beaker begins to become turbid. Wait until the deionized water is added and continue stirring for 10 minutes to stabilize the polyurethane microspheres.

[0100] Subsequently, the acetone was removed by a rotary evaporator, and then the supernatant was removed by a high-speed centrifuge at 8000 rpm for 30 minutes, and the centrifuged product was washed with deionized water. The above centrifugation and washing operations were repeated 3 times, and then the centrifuged product was dispersed in water again, and the water was removed by a freeze dryer to obtain a monodisperse submicron polyurethane microsphere solid powder.

[0101] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for preparing monodisperse submicron polyurethane microspheres, characterized in that The steps include: (1) preparing a diisocyanate and a diol with a carboxylic acid or sulfonic acid group into solutions respectively with a solvent, wherein the molar ratio of the diisocyanate to the diol with a carboxylic acid or sulfonic acid group is (1.0-1.5):1; dripping the diisocyanate solution into the diol solution with a carboxylic acid or sulfonic acid group under an oil bath and magnetic stirring, and reacting at 30-60° C. for 4-6 hours after the diisocyanate solution is dripped, and after the reaction is completed, pouring the product into a polytetrafluoroethylene mold or a glass culture dish, and drying in an oven at 80° C. for 48 hours to remove the solvent, thereby obtaining a polyurethane powder; (2) adding the polyurethane powder obtained in step (1) to a mixed solvent of acetone and water, and completely dissolving the polyurethane powder under magnetic stirring to obtain a polyurethane solution; injecting deionized water dropwise into the polyurethane solution using a syringe pump while controlling the flow rate, and after the deionized water is added dropwise, continuing to stir for 10 minutes to obtain a polyurethane microsphere emulsion; (3) The polyurethane microsphere emulsion obtained in step (2) is first evaporated by a rotary evaporator to remove acetone, and then the remaining emulsion is centrifuged to remove the supernatant, and the centrifuged product is washed with deionized water, and the above centrifugation and washing operations are repeated 2 to 3 times, and then the centrifuged product is dispersed in water again, freeze-dried or spray-dried to remove water, to obtain monodisperse submicron polyurethane microspheres.

2. The method for preparing monodisperse submicron polyurethane microspheres according to claim 1, characterized in that: The diisocyanate described in step (1) is toluene-2,4-diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate or meta-xylylene diisocyanate.

3. The method for preparing monodisperse submicron polyurethane microspheres according to claim 1, characterized in that: The diol with a carboxylic acid or sulfonic acid group in step (1) is 2,2-dihydroxymethylpropionic acid, 2,2-dihydroxymethylbutyric acid, dihydroxybenzoic acid, N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid or N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid sodium salt.

4. The method for preparing monodisperse submicron polyurethane microspheres according to claim 1, characterized in that: The solvent in step (1) is acetone, tetrahydrofuran, N,N-dimethylformamide, dimethyl sulfoxide, ethyl acetate, toluene or dioxane.

5. The method for preparing monodisperse submicron polyurethane microspheres according to claim 1, characterized in that: The time required for the polyurethane powder to be completely dissolved under the magnetic stirring in step (2) is 10 minutes; the volume ratio of acetone to water in the acetone and water mixed solvent is 8:2; the solid-liquid ratio of the polyurethane powder to the mixed solvent is 2 mg:1 ml to 4 mg:1 ml; and the dropping speed is 1.25-11 ml / min.

6. The method for preparing monodisperse submicron polyurethane microspheres according to claim 1, characterized in that: The centrifugation in step (3) is carried out at a speed of 5000-13000 r / min for 10-30 minutes.

7. A monodisperse submicron polyurethane microsphere prepared by the preparation method according to any one of claims 1 to 6, characterized in that: The particle size of the monodisperse submicron polyurethane microspheres is 100nm-1μm, and the PDI reaches 0.

005.

8. Use of the monodisperse submicron polyurethane microspheres according to claim 7 in the field of photonic crystals or drug release.

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