Surface functionalized microspheres and modification method thereof

Abstract

The invention relates to the technical field of microsphere modification, in particular to a surface-functionalized microsphere and a modification method thereof.The modification method of the surface-functionalized microsphere comprises the steps that a microsphere solution obtained by mixing a microsphere with double-bond olefin on the surface and an organic solvent is mixed with molecules containing alkenyl functional groups and an azo initiator; and carrying out addition reaction to obtain the surface functionalized microspheres. Functional groups on the surfaces of the microspheres are modified by adopting an atom transfer radical polymerization method, double-bond olefin externally hung on the surfaces of the microspheres and molecules containing alkenyl functional groups are utilized, the molecules containing the alkenyl functional groups and the double-bond olefin on the surfaces of the microspheres can be subjected to an addition reaction under the action of an azo initiator, and the functional group molecules are grafted to the surfaces of the microspheres, so that the microspheres are prepared. The surfaces of the microspheres are modified into functional groups with different contents and different lengths. According to the method, the surface groups of the microspheres can be uniformly modified, and the surfaces of the microspheres can be modified into different numbers of functional groups and functional molecules with different chain lengths.

Description

Technical Field

[0001] This invention relates to the field of microsphere modification technology, and more particularly to a surface-functionalized microsphere and its modification method. Background Technology

[0002] Depending on the properties of the material, the methods for modifying the functional groups on the surface of microspheres also vary. The uniformity of the functional group modification directly affects the performance of the microspheres. Common materials for functional microsphere surfaces include silica, polystyrene, and polymethyl methacrylate, and the commonly used modification methods are copolymerization and swelling.

[0003] However, copolymerization is currently the most common method for modifying polystyrene microspheres and polymethyl methacrylate microspheres. The disadvantage of this method is that the content and number of functional groups on the surface cannot be controlled, and it is difficult to synthesize functional groups of different lengths on the surface. On the other hand, the swelling method for modifying functional groups is complicated and the experimental process is uncontrollable.

[0004] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a surface-functionalized microsphere and its modification method, which aims to solve the problems of uncontrollable group content and difficulty in synthesizing functional groups of different lengths in existing microsphere modification methods.

[0006] The technical solution of the present invention is as follows:

[0007] A method for modifying surface-functionalized microspheres, comprising the steps of:

[0008] Microspheres with double-bonded olefins on their surface are mixed with an organic solvent to obtain a microsphere solution;

[0009] The microsphere solution was mixed with an alkenyl functional group molecule and an azo initiator, and an addition reaction was carried out at 65℃-80℃ for 18h-30h to obtain surface-functionalized microspheres.

[0010] The surface-functionalized microsphere modification method, wherein the microspheres with double-bonded olefins on their surface include one or more of polystyrene microspheres, polymethyl methacrylate microspheres, and silica microspheres with double-bonded olefins on their surface.

[0011] The method for modifying microspheres with double-bonded olefins on their surface includes, wherein the method for synthesizing the polystyrene microspheres includes one of emulsion polymerization, dispersion polymerization, suspension polymerization, and soap-free emulsion polymerization.

[0012] The surface-functionalized microsphere modification method wherein the alkenyl functional group-containing molecule includes one or more of acrylic acid, methacrylic acid, glycidyl methacrylate, 2-hydroxyethyl methacrylate, methyl methacrylate, acrylamide, and sodium styrenesulfonate.

[0013] The surface-functionalized microsphere modification method, wherein the azo initiator includes one or more of benzoyl peroxide, azobisisobutyronitrile, and azodicyanovalerate.

[0014] The surface-functionalized microsphere modification method, wherein the organic solvent includes one or more of ethanol, methanol, and isopropanol.

[0015] The surface-functionalized microsphere modification method wherein the mass ratio of the microsphere with double-bonded olefins on its surface to the molecule containing alkenyl functional groups is 1:(1-3).

[0016] The surface-functionalized microsphere modification method wherein the mass ratio of the microsphere with double-bonded olefins on its surface to the azo initiator is (8-12):1.

[0017] A surface-functionalized microsphere is prepared by a modification method for the surface-functionalized microsphere.

[0018] Beneficial Effects: This invention provides surface-functionalized microspheres and a modification method thereof. The modification method for surface-functionalized microspheres includes the following steps: mixing microspheres with double-bonded olefins on their surface with an organic solvent to obtain a microsphere solution; mixing the microsphere solution with alkenyl functional group molecules and an azo initiator, and then performing an addition reaction to obtain surface-functionalized microspheres. This invention employs atom transfer radical polymerization to modify the functional groups on the surface of microspheres. Utilizing the double-bonded olefins attached to the microsphere surface and the alkenyl functional group molecules, under the action of an azo initiator, the alkenyl functional group molecules can react with the double-bonded olefins on the microsphere surface through an addition reaction, grafting functional group molecules onto the microsphere surface. This modifies the microsphere surface with functional groups of different contents and lengths, such as carboxyl, amino, and sulfonic acid groups. This modification method allows for uniform modification of the microsphere surface groups, enabling the microsphere surface to be modified with different numbers of functional groups and functional molecules of different chain lengths. Furthermore, the modification method is simple and easy to operate, allowing for large-scale preparation. Attached Figure Description

[0019] Figure 1 This is a flowchart illustrating a method for surface-functionalized microsphere modification.

[0020] Figure 2 The graph shows the change in conductivity of the acrylic acid-modified polystyrene microspheres prepared in Example 1.

[0021] Figure 3 The graph shows the change in conductivity of the acrylamide-modified polystyrene microspheres prepared in Example 2.

[0022] Figure 4 The graph shows the change in conductivity of the acrylic acid-modified silica microspheres prepared in Example 3. Detailed Implementation

[0023] This invention provides surface-functionalized microspheres and a method for modifying them. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0024] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0025] Common methods for microsphere modification include copolymerization, which involves adding functional group molecules during microsphere synthesis, copolymerizing with styrene, or swelling, where the modifying groups are attached to the microspheres after synthesis by a swelling agent. However, microsphere modification methods based on copolymerization and swelling suffer from uncontrollable group content and difficulty in synthesizing functional groups of different lengths.

[0026] Based on this, such as Figure 1 As shown, the present invention provides a method for modifying surface-functionalized microspheres, comprising the following steps:

[0027] Step S10: Mix the microspheres with double-bonded olefins on their surface with an organic solvent to obtain a microsphere solution;

[0028] Step S20: The microsphere solution is mixed with an alkenyl functional group molecule and an azo initiator, and an addition reaction is carried out at 65℃-80℃ for 18h-30h to obtain surface-functionalized microspheres.

[0029] In this embodiment, atom transfer radical polymerization is used to modify the functional groups on the surface of microspheres. Utilizing double-bonded olefins attached to the microsphere surface and alkenyl-containing functional group molecules, under the action of an azo initiator, the alkenyl-containing functional group molecules can undergo addition reactions with the double-bonded olefins on the microsphere surface, grafting functional group molecules onto the microsphere surface. This modifies the microsphere surface with functional groups of different contents and lengths, such as carboxyl, amino, and sulfonic acid groups. This modification method allows for uniform modification of the microsphere surface, enabling the creation of different numbers of functional groups and functional molecules of different chain lengths. Furthermore, the modification method is simple and easy to operate, allowing for large-scale preparation.

[0030] Specifically, this invention employs atom transfer radical polymerization to modify the functional groups on the surface of microspheres. Utilizing the large number of carbon-carbon double bond functional groups on the tail surface, under the action of an azo initiator, the functional group molecules containing carbon-carbon double bonds can undergo addition reactions with the carbon-carbon double bonds on the microsphere surface to generate carbon-carbon single bonds, thus giving the microsphere surface functional groups such as carboxyl, amino, and sulfonic acid groups. The advantage of this modification method is that it can uniformly modify the functional groups on the microsphere surface, allowing the microsphere surface to be modified with different numbers of functional groups and functional molecules of different chain lengths.

[0031] In some embodiments, the microspheres with double-bonded olefins on their surface include, but are not limited to, one or more of polystyrene microspheres, polymethyl methacrylate microspheres, and silica microspheres with double-bonded olefins on their surface. Polystyrene and polymethyl methacrylate microspheres, due to the presence of numerous double-bonded olefins on their surfaces, can undergo addition reactions with alkenyl-containing functional group molecules under the action of azo initiators, thus grafting the functional group molecules onto the microsphere surface. Silica microspheres, on the other hand, require treatment with vinyltrimethoxysilane to form silica microspheres with double-bonded olefins.

[0032] In some embodiments, the synthesis methods of the microspheres with double-bonded olefins on their surface include emulsion polymerization, dispersion polymerization, suspension polymerization, soap-free emulsion polymerization, etc.

[0033] This embodiment takes the preparation of polystyrene microspheres by emulsion polymerization as an example. The raw materials for the synthesis of polystyrene microspheres by emulsion polymerization include surfactants, initiators, styrene monomers, divinylbenzene as a crosslinking agent, and ultrapure water.

[0034] In some embodiments, the surfactant includes, but is not limited to, one or more of sodium dodecyl sulfonate, polyvinylpyrrolidone 29000, polyvinylpyrrolidone 40000, polyvinylpyrrolidone 10000, and polyvinyl alcohol 1788; the initiator includes, but is not limited to, one or more of potassium persulfate and ammonium persulfate.

[0035] In some embodiments, the polystyrene microsphere synthesis conditions include an initiator comprising 0.01%-0.05% of the monomer by mass, a crosslinking agent comprising 1%-10% of the monomer, and a surfactant comprising 0.01%-0.05% of the monomer. The polymerization temperature is 65°C-70°C, and the polymerization time is 5-24 hours.

[0036] Specifically, 200 nm polystyrene microspheres were prepared by emulsion polymerization. The reaction system consisted of 10 ml of reaction mixture, 9 ml of ultrapure water, 1 ml of styrene, 0.1 ml of divinylbenzene, 5 mg of potassium persulfate, and SDS with a final concentration of 0.005%. The reaction was carried out at 70 °C for 24 h under nitrogen protection.

[0037] In some embodiments, the alkenyl-containing functional group molecule includes, but is not limited to, one or more of acrylic acid, methacrylic acid, glycidyl methacrylate, 2-hydroxyethyl methacrylate, methyl methacrylate, acrylamide, and sodium styrenesulfonate. All of the above functional group molecules contain an alkenyl group, which, under the action of an azo initiator, can undergo an addition reaction with the double-bonded olefins on the microsphere surface to form carbon-carbon single bonds, thereby grafting the functional group molecule onto the microsphere surface. Simultaneously, the alkenyl-containing functional group molecule can be selected according to actual needs, allowing the microsphere surface to be modified with functional groups of different contents and lengths.

[0038] In some embodiments, the azo initiator includes, but is not limited to, one or more of benzoyl peroxide, azobisisobutyronitrile, and azodicyanovalerate. These azo initiators enable an addition reaction between the double-bonded olefins on the microsphere surface and the alkenyl groups on the functional group molecules, thereby achieving the grafting of the functional group molecules onto the microspheres.

[0039] In some embodiments, the organic solvent includes, but is not limited to, one or more of ethanol, methanol, and isopropanol. This provides a liquid environment for the addition reaction of microspheres containing double-bonded olefins with alkenyl functional groups, accelerating the reaction. Furthermore, the aforementioned organic solvents are non-toxic, harmless, and volatile.

[0040] In some embodiments, the addition reaction is carried out at a temperature of 65°C-80°C for 18-30 hours. At this temperature and time, the microspheres of the double-bonded olefin and the molecule containing the alkenyl functional group can undergo an addition reaction under the action of an azo initiator.

[0041] In a preferred embodiment, the addition reaction is carried out at a temperature of 70°C for 24 hours.

[0042] Specifically, taking polystyrene microspheres and methacrylic acid as examples, the polystyrene microspheres prepared by emulsion polymerization were repeatedly washed with ethanol / water three to five times and dried; 100 mg of polystyrene microspheres were weighed, dispersed in 20 ml of ethanol, 100 μl of methacrylic acid was added, and 10 mg of azobisisobutyronitrile was added. Under nitrogen protection, the mixture was reacted at 70 °C for 24 h. After the reaction was completed, the mixture was repeatedly washed with ethanol / water five times, dried, and weighed.

[0043] Taking polystyrene microspheres and glycidyl methacrylate as an example, 100 mg of polystyrene microspheres were weighed and dispersed in 20 ml of ethanol. 100 μl of glycidyl methacrylate and 10 mg of azobisisobutyronitrile were added. The mixture was reacted at 70 °C for 24 h under nitrogen protection. After the reaction, the mixture was washed repeatedly with ethanol / water 5 times. 0.1 g of glycine was weighed and dissolved in 10 ml of ultrapure water. The pH was adjusted to 10. The microspheres modified with glycidyl methacrylate were mixed evenly with the glycine solution and reacted for 24 h. After the reaction, the mixture was washed three times with ultrapure water, dried, and weighed.

[0044] In this embodiment, taking the content of modified carboxyl molecules as an example, the carboxyl content of the modified microspheres is determined by back titration. Back titration is a commonly used method for testing carboxyl, amino, and hydroxyl groups. The principle of back titration for determining carboxyl content is to react excess alkali with the carboxyl groups, and then back titrate the remaining alkali with acid, thereby accurately determining the carboxyl content. This method is suitable for situations where the carboxyl content is low or the reaction rate is slow, and can provide relatively accurate analytical results.

[0045] Specifically, the test for the number of carboxyl groups in the microspheres includes the following steps: Weigh 100 mg of microspheres, disperse them in ultrapure water, add 1 M sodium hydroxide, adjust the conductivity to around 500 μS / cm, and react for 30 minutes; then titrate the above solution with 0.1 M hydrochloric acid until the conductivity changes to a constant value, and record the amount of hydrochloric acid used within the constant value range; finally, calculate the content of carboxyl groups. The calculation formula is: Concentration = (0.1 M hydrochloric acid × volume) / (mass of microspheres).

[0046] The amino group content test of the microspheres includes the following steps: Weigh 100 mg of microspheres, disperse them in ultrapure water, add 1 M hydrochloric acid, adjust the conductivity to around 500 μS / cm, and react for 30 minutes; then titrate the above solution with 0.1 M sodium hydroxide until the conductivity changes to a constant value, record the amount of sodium hydroxide used within the constant value range, and finally calculate the amino group content. The calculation formula is: Concentration = (0.1 M sodium hydroxide × volume) / (mass of microspheres).

[0047] In some embodiments, the mass ratio of the microspheres with double-bonded olefins to the alkenyl-containing functional group molecules is 1:(1-3). By controlling the mass ratio of the microspheres with double-bonded olefins to the alkenyl-containing functional group molecules within this range, the surface groups of the microspheres can be uniformly modified, and the surface of the microspheres can be modified with different numbers of functional groups and functional molecules with different chain lengths.

[0048] In a preferred embodiment, the mass ratio of the microspheres with double-bonded olefins on their surface to the molecules containing alkenyl functional groups is 1:1.

[0049] In some embodiments, the mass ratio of the microspheres with double-bonded olefins to the azo initiator is (8-12):1. This mass ratio can increase the rate of the addition reaction and shorten the preparation time.

[0050] In a preferred embodiment, the mass ratio of the microspheres with double-bonded olefins on their surface to the azo initiator is 10:1.

[0051] In addition, the present invention also provides a surface-functionalized microsphere, which is prepared by a modification method of the surface-functionalized microsphere.

[0052] In this embodiment, the modification method can uniformly modify the surface groups of microspheres, and the surface of microspheres can be modified with different numbers of functional groups and functional molecules with different chain lengths. Moreover, the modification method is simple and easy to operate, and can achieve large-scale preparation.

[0053] The following examples further illustrate the present invention in detail. It should also be understood that the following examples are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention are within the scope of protection of the present invention.

[0054] Example 1

[0055] This embodiment prepares acrylic acid-modified polystyrene microspheres, including the following steps:

[0056] Weigh 100 mg of polystyrene microspheres and disperse them in 20 ml of ethanol. Add 100 μl of acrylic acid and 10 mg of azobisisobutyronitrile. Under nitrogen protection, react at 70 °C for 24 h. After the reaction is complete, wash the microspheres five times with ethanol / water, dry them, and weigh them.

[0057] To test the carboxyl content of the acrylic acid-modified polystyrene microspheres: 100 mg of the acrylic acid-modified polystyrene microspheres prepared in this example was weighed, dispersed in ultrapure water, and 1 M sodium hydroxide was added to adjust the conductivity to around 500 μS / cm. The reaction was allowed to proceed for 30 minutes. Then, the solution was titrated with 0.1 M hydrochloric acid until the conductivity reached a constant value. The amount of hydrochloric acid used within the constant value range was recorded. Finally, the carboxyl content was calculated, as shown in Table 1. The conductivity change curve of the acrylic acid-modified polystyrene microspheres is shown in the figure. Figure 2 As shown. Calculation formula: Concentration = (0.1M hydrochloric acid × volume) / (microsphere mass), and the measured carboxyl content is 1000 μmol / g.

[0058] Table 1

[0059]

[0060]

[0061] Example 2

[0062] This embodiment prepares acrylamide-modified polystyrene microspheres, including the following steps:

[0063] Weigh 100 mg of polystyrene microspheres and disperse them in 20 ml of ethanol. Add 0.1 g of acrylamide and 10 mg of azobisisobutyronitrile. Under nitrogen protection, react at 70 °C for 24 h. After the reaction is complete, wash repeatedly with ethanol / water 5 times, dry, and weigh.

[0064] The amino content of the acrylamide-modified polystyrene microspheres prepared in this embodiment was tested as follows: 100 mg of the acrylamide-modified polystyrene microspheres prepared in this embodiment was weighed, dispersed in ultrapure water, and 1 M hydrochloric acid was added to adjust the conductivity to around 500 μS / cm. The reaction was allowed to proceed for 30 minutes. Then, the solution was titrated with 0.1 M sodium hydroxide until the conductivity reached a constant value. The amount of sodium hydroxide used within the constant value range was recorded, and the amino content was calculated. The details are shown in Table 2. The conductivity change curve of the acrylamide-modified polystyrene microspheres is shown in the figure below. Figure 3 As shown. Calculation formula: Concentration = (0.1M sodium hydroxide × volume) / (microsphere mass). The tested amino content was 800 μmol / g.

[0065] Table 2

[0066]

[0067]

[0068] Example 3

[0069] This embodiment prepares acrylic acid-modified silica microspheres, including the following steps:

[0070] 0.1 g of silica microspheres were dispersed in 30 ml of toluene solution, and 60 μl of vinyltrimethoxysilane was added. The reaction was carried out at 100 °C for 6 hours. After the reaction was completed, the toluene was removed by centrifugation, and the surface-treated silica microspheres were collected and washed three times with ethanol / water.

[0071] After washing and drying, the surface-treated silica microspheres were dispersed in 20 ml of ethanol, 100 μl of acrylic acid and 10 mg of azobisisobutyronitrile were added, and the mixture was reacted at 70 °C for 24 h under nitrogen protection. After the reaction was completed, the microspheres were washed repeatedly with ethanol / water 5 times, dried, and weighed.

[0072] To test the carboxyl content of the acrylic acid-modified silica microspheres: 100 mg of the acrylic acid-modified silica microspheres prepared in this example was weighed, dispersed in ultrapure water, and 1 M sodium hydroxide was added to adjust the conductivity to around 500 μS / cm. The reaction was allowed to proceed for 30 minutes. Then, the solution was titrated with 0.1 M hydrochloric acid until the conductivity reached a constant value. The amount of hydrochloric acid used within the constant value range was recorded. Finally, the carboxyl content was calculated, as shown in Table 3. The conductivity change curve of the acrylic acid-modified silica microspheres is shown in the figure below. Figure 4 As shown. Calculation formula: Concentration = (0.1M hydrochloric acid × volume) / (microsphere mass), the tested amino content: 1200 μmol / g.

[0073] Table 3

[0074]

[0075]

[0076] In summary, this invention provides a surface-functionalized microsphere and its modification method. The modification method for the surface-functionalized microsphere includes the following steps: mixing microspheres with double-bonded olefins on their surface with an organic solvent to obtain a microsphere solution; mixing the microsphere solution with alkenyl functional group molecules and an azo initiator, and then performing an addition reaction to obtain surface-functionalized microspheres. This invention employs atom transfer radical polymerization to modify the functional groups on the surface of the microspheres. Utilizing the double-bonded olefins attached to the microsphere surface and the alkenyl functional group molecules, under the action of an azo initiator, the alkenyl functional group molecules can react with the double-bonded olefins on the microsphere surface through an addition reaction, grafting functional group molecules onto the microsphere surface. This modifies the microsphere surface with functional groups of different contents and lengths, such as carboxyl, amino, and sulfonic acid groups. This modification method allows for uniform modification of the microsphere surface groups, enabling the microsphere surface to be modified with different numbers of functional groups and functional molecules of different chain lengths. Furthermore, the modification method is simple and easy to operate, allowing for large-scale preparation.

[0077] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for modifying surface-functionalized microspheres, characterized in that, Including the following steps: Microspheres with double-bonded olefins on their surface are mixed with an organic solvent to obtain a microsphere solution; The microsphere solution was mixed with an alkenyl functional group molecule and an azo initiator, and an addition reaction was carried out at 65℃-80℃ for 18h-30h to obtain surface-functionalized microspheres.

2. The method for modifying surface-functionalized microspheres according to claim 1, characterized in that, The microspheres with double-bonded olefins on their surface include one or more of polystyrene microspheres, polymethyl methacrylate microspheres, and silica microspheres with double-bonded olefins on their surface.

3. The method for modifying surface-functionalized microspheres according to claim 2, characterized in that, The method for synthesizing the microspheres with double-bonded olefins on the surface includes one of emulsion polymerization, dispersion polymerization, suspension polymerization, and soap-free emulsion polymerization.

4. The method for modifying surface-functionalized microspheres according to claim 1, characterized in that, The alkenyl functional group-containing molecule includes one or more of acrylic acid, methacrylic acid, glycidyl methacrylate, 2-hydroxyethyl methacrylate, methyl methacrylate, acrylamide, and sodium styrene sulfonate.

5. The method for modifying surface-functionalized microspheres according to claim 1, characterized in that, The azo initiators include one or more of benzoyl peroxide, azobisisobutyronitrile, and azobiscyanopentanoic acid.

6. The method for modifying surface-functionalized microspheres according to claim 1, characterized in that, The organic solvent includes one or more of ethanol, methanol, and isopropanol.

7. The method for modifying surface-functionalized microspheres according to claim 1, characterized in that, The mass ratio of the microspheres with double-bonded olefins on their surface to the molecules containing alkenyl functional groups is 1:(1-3).

8. The method for modifying surface-functionalized microspheres according to claim 1, characterized in that, The mass ratio of the microspheres with double-bonded olefins on their surface to the azo initiator is (8-12):

1.

9. A surface-functionalized microsphere, characterized in that, The microspheres were prepared using the surface-functionalized microsphere modification method as described in any one of claims 1-8.

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