A method for preparing porous functional microspheres

Abstract

The present invention provides a method for preparing porous functional microspheres, comprising the following steps: A) mixing a polymerization monomer, an initiator, a dispersant, a cross-linking agent and a functional monomer in a dispersion medium, reacting to obtain monodispersed functional microspheres; B) dispersing the monodispersed functional microspheres in a good solvent and stirring to obtain monodispersed porous functional microspheres; the good solvent is a solvent with a solubility of 8.0 to 10.0 (Cal / em 3 ) 1 / 2 The present invention adopts the technical scheme of dispersion polymerization + good solvent dissolution, and can obtain monodisperse and functional porous polymer microspheres with only one step of polymerization and one step of post-treatment, which simplifies the preparation steps, and the prepared porous polymer microspheres have stable quality and good controllability.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer material synthesis, and in particular relates to a method for preparing porous functional microspheres. Background Art

[0002] As a new type of functional material, porous polymer microspheres are a major research hotspot in the field of polymer materials. They have many advantages such as good sphericity, large specific surface area, low skeleton density, strong adsorption, high mechanical strength, and easy surface modification. They have broad application prospects in the fields of biomedicine, analytical chemistry, environmental protection, catalyst carriers, and electronic products.

[0003] At present, the main methods for preparing porous microspheres are suspension polymerization and seed swelling method.

[0004] The suspension polymerization method is that the organic phase (including monomers and porogens) containing an initiator is dispersed in the form of droplets in an aqueous phase containing a stabilizer under mechanical stirring. After a cross-linking polymerization reaction occurs in the droplets, the porogen is removed to obtain porous polymer microspheres. The conventional suspension polymerization method is simple to operate and can prepare polymer microspheres of 2-2000μm, but the particle size of the microspheres prepared by this method is polydisperse, which limits its scope of application. For example, Chinese invention patent CN 113045705 B prepares porous microspheres by a one-pot suspension polymerization method, and the porous microspheres can be further hydrophilically modified, but the prepared microspheres are polydisperse.

[0005] The seed swelling method is generally considered to be a better method for preparing monodisperse porous polymer microspheres. First, small-size monodisperse seed microspheres are prepared by soap-free emulsion or dispersion polymerization, and then the seed microspheres are swollen with monomers, initiators and porogens. After the reaction, the porogens are removed to generate porous microspheres. This method has obvious advantages in preparing surface functionalized, monodisperse large-size polymer microspheres. However, this method has complicated steps and a long cycle. For example, Chinese invention patent CN 112608404B first prepares polystyrene microspheres, then sulfonates them, and then swells and polymerizes them to obtain amino-functionalized porous microspheres. The whole process includes two polymerizations, one surface treatment, and one swelling.

[0006] In addition, there are some preparation methods, such as the invention patent CN 112535759 A, which uses the Picking emulsion method to prepare micro / nano graded porous microspheres, but the microspheres are polydisperse. Summary of the invention

[0007] The object of the present invention is to provide a method for preparing porous functional microspheres. The preparation method of the present invention has simple steps, and the prepared porous microspheres have monodispersity and functionality.

[0008] The present invention provides a method for preparing porous functional microspheres, comprising the following steps:

[0009] A) mixing a polymerization monomer, an initiator, a dispersant, a cross-linking agent and a functional monomer in a dispersion medium, reacting to obtain monodispersed functional microspheres;

[0010] B) dispersing the monodisperse functional microspheres in a good solvent and stirring to obtain monodisperse porous functional microspheres;

[0011] The good solvent has a solubility of 8.0 to 10.0 (Cal / em 3 ) 1 / 2 of solvent.

[0012] Preferably, the polymerizable monomer is a monomer containing a vinyl group.

[0013] Preferably, the initiator is azobisisobutyronitrile and / or azobisisovaleronitrile; the mass of the initiator is 1% to 4% of the mass of the polymerization monomer.

[0014] Preferably, the dispersant is one or more of polyvinyl pyrrolidone, sodium styrene sulfonate, Triton X-100, Triton X-114, Triton X-305, Triton X-405 and Triton X-705;

[0015] The mass of the dispersant is 2-20 wt % of the mass of the polymerized monomer.

[0016] Preferably, the cross-linking agent has a structure shown in Formula 1:

[0017]

[0018] In formula 1, n is 0 or 1, R 1 , R 3 and R 4 Independently selected from -H or CH 3 ; R 2 for

[0019]

[0020] The mass of the cross-linking agent is 0.5% to 5% of the mass of the polymerized monomer.

[0021] Preferably, the reaction temperature in step A) is 65-80° C., and the reaction time in step A) is 8-12 hours.

[0022] Preferably, the crosslinking agent is added within 0 to 2 hours from the start of the reaction.

[0023] Preferably, the dispersion medium is alcohol or an alcohol-water mixture; in the alcohol-water mixture, the volume ratio of alcohol to water is 9:1 to 6:4.

[0024] Preferably, the good solvent is toluene and / or tetrahydrofuran.

[0025] Preferably, the stirring time in step B) is 0.5 to 6 hours.

[0026] Preferably, the porous functional microspheres have a hollow structure, a gradient pore structure or a uniform pore structure.

[0027] The present invention provides a method for preparing porous functional microspheres, comprising the following steps: A) mixing a polymerization monomer, an initiator, a dispersant, a cross-linking agent and a functional monomer in a dispersion medium, reacting to obtain monodispersed functional microspheres; B) dispersing the monodispersed functional microspheres in a good solvent and stirring to obtain monodispersed porous functional microspheres; the good solvent is a solvent with a solubility of 8.0 to 10.0 (Cal / em 3 ) 1 / 2 The present invention adopts the technical scheme of dispersion polymerization + good solvent dissolution, and can obtain monodisperse and functional porous polymer microspheres with only one step of polymerization and one step of post-treatment, which simplifies the preparation steps, and the prepared porous polymer microspheres have stable quality and good controllability. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0029] Figure 1 is a SEM image of the porous functional microspheres in Example 1 of the present invention;

[0030] Figure 2 is a SEM image of the porous functional microspheres in Example 2 of the present invention;

[0031] Figure 3 is a SEM image of the porous functional microspheres in Example 3 of the present invention;

[0032] Figure 4 is a SEM image of the porous functional microspheres in Example 4 of the present invention;

[0033] Figure 5 is a SEM image of the porous functional microspheres in Example 5 of the present invention;

[0034] Figure 6is a SEM image of the porous functional microspheres in Example 6 of the present invention;

[0035] Figure 7 is a SEM image of the porous functional microspheres in Example 7 of the present invention;

[0036] Figure 8 is a SEM image of the porous functional microspheres in Example 8 of the present invention;

[0037] Fig. 9 is a SEM image of the porous functional microspheres in Example 9 of the present invention;

[0038] Fig.10 is a SEM image of the porous functional microspheres in Example 10 of the present invention;

[0039] Fig.11 is a SEM image of the porous functional microspheres in Example 11 of the present invention;

[0040] Fig.12 This is a SEM image of the porous functional microspheres in Example 12 of the present invention. DETAILED DESCRIPTION

[0041] The present invention provides a method for preparing porous functional microspheres, comprising the following steps:

[0042] A) mixing a polymerization monomer, an initiator, a dispersant, a cross-linking agent and a functional monomer in a dispersion medium, reacting to obtain monodispersed functional microspheres;

[0043] B) dispersing the monodisperse functional microspheres in a good solvent and stirring to obtain monodisperse porous functional microspheres;

[0044] The good solvent has a solubility of 8.0 to 10.0 (Cal / em 3 ) 1 / 2 of solvent.

[0045] In the present invention, preferably, the polymerization monomer, initiator, dispersant, crosslinking agent and functional monomer are mixed in a dispersion medium to carry out a dispersion polymerization reaction to obtain monodisperse functional microspheres.

[0046] In the present invention, the polymerizable monomer is preferably a monomer containing a vinyl group, such as a styrene monomer, and the mass of the polymerizable monomer is preferably 8% to 25% of the mass of the entire system, more preferably 10% to 20%.

[0047] In the present invention, the initiator is preferably azobisisobutyronitrile and / or azobisisovaleronitrile; the mass of the initiator is preferably 1% to 4% of the mass of the polymerizable monomer, more preferably 2% to 3%.

[0048] In the present invention, the dispersant is preferably one or more of polyvinyl pyrrolidone, sodium styrene sulfonate, Triton X-100, Triton X-114, Triton X-305, Triton X-405 and Triton X-705, and at least one ionic dispersant; the mass of the dispersant is preferably 2 to 20 wt % of the mass of the polymerized monomer, more preferably 5 to 15 wt %, such as 2 wt %, 5 wt %, 8 wt %, 10 wt %, 12 wt %, 15 wt %, 18 wt %, 20 wt %, preferably a range value with any of the above values ​​as the upper or lower limit.

[0049] In the present invention, the cross-linking agent preferably has a structure shown in Formula 1:

[0050]

[0051] In formula 1, n is 0 or 1, R 1 , R 3 and R 4 Independently selected from -H or CH 3 ; R 2 for

[0052]

[0053] Specifically, in an embodiment of the present invention, the cross-linking agent can be one or more of polyethylene glycol diacrylate (PEGDA), ethylene glycol dimethacrylate (EGDMA), trimethylolpropane triacrylate (TMPTA) and divinylbenzene (DVB); the mass of the cross-linking agent is preferably 0.5% to 5% of the mass of the polymerized monomer, more preferably 1% to 4%, such as 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, preferably a range value with any of the above values ​​as the upper or lower limit.

[0054] According to the research of the present invention, the addition time, type and amount of the crosslinking agent all affect the pore structure of the porous microspheres. The earlier the crosslinking agent is added, the easier it is to form a uniform pore structure inside the microspheres; the shorter the crosslinking agent chain, the easier it is to form a uniform crosslinking structure; the more double bonds the crosslinking agent has, the easier it is to form a uniform structure; the larger the amount of crosslinking agent used, the easier it is to form a uniform crosslinking structure.

[0055] In the present invention, functional monomers may also be added, such as functional monomers containing one or more of a carboxyl group, an amino group, an amine group or an epoxy group. Specifically, in an embodiment of the present invention, the functional monomer may be one or more of methacrylic acid (MAA), acrylamide (AM) and polyethyleneimine (PEI); the mass of the functional monomer is preferably 0 to 5% of the mass of the polymerized monomer, more preferably 0.5 to 4.5%, such as 0%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, preferably a range value with any of the above values ​​as the upper or lower limit.

[0056] In the present invention, the dispersion medium is preferably alcohol or an alcohol-water mixture; according to the present invention, the smaller the polarity of the dispersion medium, the easier it is to form a uniform pore structure inside the microsphere. In the alcohol-water mixture, the volume ratio of alcohol to water is preferably 9:1 to 6:4, more preferably 8:2 to 7:3, such as 9:1, 8:2, 7:3, 6:4 or 5:5.

[0057] In the present invention, the reaction temperature of the dispersion polymerization is preferably 65 to 80° C., more preferably 70 to 75° C., the reaction time of the dispersion polymerization is preferably 8 to 12 hours, more preferably 9 to 11 hours, and most preferably 10 to 11 hours. The dispersion polymerization is preferably carried out under stirring conditions, and the stirring speed is preferably 150 to 300 r / min, more preferably 200 to 250 r / min.

[0058] After solid-liquid separation such as centrifugal washing, a monodisperse functional microsphere solid is obtained. The particle size of the monodisperse functional microsphere obtained in the present invention is preferably 0.2-3 μm, and the particle size distribution CV is less than 5%.

[0059] After obtaining the monodisperse functional microspheres, the present invention disperses them in a good solvent and stirs them, washes them after solid-liquid separation, and dries them to obtain monodisperse porous functional microspheres.

[0060] In the present invention, the good solvent can dissolve linear polystyrene, and the good solvent can have a solubility parameter range of 8.0 to 10.0 (Cal / em 3 ) 1 / 2 The solvent in the range of 8.5 to 9.5 (Cal / em 3 ) 1 / 2 , specifically, it may be toluene and / or tetrahydrofuran.

[0061] In the present invention, the stirring time is preferably 0.5 to 6 hours, more preferably 0.5 to 2 hours, and most preferably 1 to 2 hours.

[0062] In the present invention, porous functional microspheres with different pore structures can be prepared by adjusting the preparation parameters, such as hollow structure, gradient pore structure or uniform pore structure. The gradient pore structure refers to the difference between the pore structures inside and outside the microsphere, with the inner pore size being large and the pore structure being loose, and the outer pore size being small and the pore structure being tight; the hollow structure refers to the microsphere having a cavity inside and a relatively tight pore structure on the outer layer; the uniform pore structure refers to the pore structure (pore size, porosity) inside and outside the microsphere being not much different, and being uniform inside and outside.

[0063] The present invention provides a method for preparing porous functional microspheres, comprising the following steps: A) mixing a polymerization monomer, an initiator, a dispersant, a cross-linking agent and a functional monomer in a dispersion medium, reacting to obtain monodispersed functional microspheres; B) dispersing the monodispersed functional microspheres in a good solvent and stirring to obtain monodispersed porous functional microspheres; the good solvent is a solvent with a solubility of 8.0 to 10.0 (Cal / em 3 ) 1 / 2 The present invention adopts the technical scheme of dispersion polymerization + good solvent dissolution, and can obtain monodisperse and functional porous polymer microspheres with only one step of polymerization and one step of post-treatment, which simplifies the preparation steps, and the prepared porous polymer microspheres have stable quality and good controllability.

[0064] In order to further illustrate the present invention, a method for preparing porous functional microspheres provided by the present invention is described in detail below in conjunction with examples, but it should not be construed as limiting the scope of protection of the present invention.

[0065] Example 1

[0066] Figure 1 , particle size ~ 1 μm: St 25ml, initiator AIMN 0.5g, dispersant PVP 1g, auxiliary dispersant TX-4050.5g, PEGDA-700 1ml, MeOH 225ml, H 2 O 25ml was added into a three-necked flask, the reaction temperature was 75℃, the stirring speed was 200r / min, and after the reaction for 2h, MAA 1.25ml was added. After the reaction was continued for 10h, centrifugal washing was performed, 100ml toluene was added to the obtained PS-PEGDA 700-carboxyl microsphere solid, stirred for 2h, centrifuged, washed with methanol twice, and dried in a vacuum oven to obtain hollow microspheres containing carboxyl groups.

[0067] Example 2

[0068] Figure 2 , particle size ~ 1 μm: St 25 ml, initiator AIMN 0.5 g, dispersant PVP 1 g, auxiliary dispersant TX-4050.5 g, PEGDA-700 1.5 ml, MeOH 225 ml, H 2O 25ml was added into a three-necked flask, the reaction temperature was 75℃, the stirring speed was 200r / min, and after the reaction for 2h, MAA 1.25ml was added. After the reaction was continued for 10h, centrifugal washing was performed, 100ml toluene was added to the obtained PS-PEGDA 700-carboxyl microsphere solid, stirred for 2h, centrifuged, washed twice with methanol, and dried in a vacuum oven to obtain carboxyl-containing gradient porous microspheres.

[0069] Example 3

[0070] Figure 3 , particle size ~ 1 μm: St 25ml, initiator AIMN 0.5g, dispersant PVP 1g, auxiliary dispersant TX-4050.5g, PEGDA-700 2ml, MeOH 225ml, H 2 O 25ml was added into a three-necked flask, the reaction temperature was 75℃, the stirring speed was 200r / min, and after the reaction for 2h, MAA 1.25ml was added. After the reaction was continued for 10h, centrifugal washing was performed, 100ml toluene was added to the obtained PS-PEGDA 700-carboxyl microsphere solid, stirred for 2h, centrifuged, washed twice with methanol, and dried in a vacuum oven to obtain uniform porous microspheres containing carboxyl groups.

[0071] Example 4

[0072] Figure 4 , particle size ~ 600nm: St 25ml, initiator AIBN 0.5g, dispersant NASS 0.5g, auxiliary dispersant TX-100 0.5g, MeOH 150ml, H 2 O 100ml, PEGDA-500 0.5ml, AM 1.26g, reaction temperature 75℃, stirring speed 200r / min, react for 8h and then centrifuge and wash, add 100ml toluene to the obtained PS-PEGDA500-amino microsphere solid, stir for 2h, centrifuge and separate, wash twice with methanol, and dry in a vacuum oven to obtain gradient porous microspheres containing amino groups.

[0073] Example 5

[0074] Figure 5 , particle size ~ 600nm: St 25ml, initiator AIBN 0.5g, dispersant NASS 0.5g, auxiliary dispersant TX-100 0.5g, MeOH 150ml, H 2O 100ml, EGDMA 0.5ml, AM 1.26g, reaction temperature 75℃, stirring speed 200r / min, react for 8h and then centrifuge and wash, add 100ml toluene to the obtained PS-EGDMA-amino microsphere solid, stir for 2h, centrifuge and separate, wash twice with methanol, and dry in a vacuum oven to obtain gradient porous microspheres containing amino groups.

[0075] Example 6

[0076] Figure 6 , particle size ~ 600nm: St 25ml, initiator AIBN 0.5g, dispersant NASS 0.5g, auxiliary dispersant TX-100 0.5g, MeOH 150ml, H 2 O 100ml, TMPTA 0.5ml, AM 1.26g, reaction temperature 75℃, stirring speed 200r / min, react for 8h and then centrifuge and wash, add 100ml toluene to the obtained PS-TMPTA-amino microsphere solid, stir for 2h, centrifuge and separate, wash twice with methanol, and dry in a vacuum oven to obtain uniform porous microspheres containing amino groups.

[0077] Example 7

[0078] Figure 7 , particle size 300nm: St 25ml, initiator AIBN 2.5g, dispersant PVP 10g, TX-7053.5g, EG200ml, H 2 O 50ml, reaction temperature 75℃, stirring speed 200r / min, after reacting for 2h, add DVB 0.5ml, PEI 6.5g, continue to react for 8h and then centrifuge and wash, add 100ml tetrahydrofuran to the obtained PS-DVB-amino microsphere solid, stir for 2h, centrifuge and separate, wash twice with methanol, and dry in a vacuum oven to obtain gradient porous microspheres containing amino groups.

[0079] Example 8

[0080] Figure 8 , particle size 300nm: St 25ml, initiator AIBN 2.5g, dispersant PVP 10g, TX-7053.5g, EG200ml, H 2 O 50ml, reaction temperature 75℃, stirring speed 200r / min, after reacting for 1h, add DVB 0.5ml, PEI 6.5g, continue to react for 8h and then centrifuge and wash, add 100ml tetrahydrofuran to the obtained PS-DVB-amino microsphere solid, stir for 2h, centrifuge and separate, wash twice with methanol, and dry in a vacuum oven to obtain gradient porous microspheres containing amino groups.

[0081] Example 9

[0082] Fig. 9 , particle size 2.8μm: St 25ml, initiator AIBN 2.5g, dispersant PVP 10g, TX-7053.5g, DVB0.5ml, EG 200ml, H 2 O 50ml, reaction temperature 75℃, stirring speed 200r / min, after reacting for 1h, add PEI 6.5g, continue to react for 8h and then centrifuge and wash, add 100ml tetrahydrofuran to the obtained PS-DVB-amino microsphere solid, stir for 2h, centrifuge and separate, wash twice with methanol, and dry in a vacuum oven to obtain gradient porous microspheres containing amino groups.

[0083] Example 10

[0084] Fig.10 , particle size 200nm: St 25ml, initiator AIBN 0.5g, dispersant NaSS 0.5g, EG 150ml, H 2 O150ml reaction temperature 75 ℃, stirring speed 200r / min, after reaction 1h, add EGDMA 0.5ml, PEI 1.26g, continue reaction for 8h and then centrifuge and wash, add 100ml toluene to the obtained PS-EGDMA-amino microsphere solid, stir for 2h, centrifuge and separate, wash twice with methanol, and dry in a vacuum oven to obtain gradient porous microspheres containing amino groups.

[0085] Embodiment 11

[0086] Fig.11 , particle size 250nm: St 25ml, initiator AIBN 0.5g, dispersant NaSS 0.5g, EG 150ml, H 2 O150ml reaction temperature 75 ℃, stirring speed 200r / min, after reaction 1h, add EGDMA 0.5ml, PEI 1.26g, continue reaction for 8h and then centrifuge and wash, add 100ml toluene to the obtained PS-EGDMA-amino microsphere solid, stir for 2h, centrifuge and separate, wash twice with methanol, and dry in a vacuum oven to obtain gradient porous microspheres containing amino groups.

[0087] Example 12

[0088] Fig.12, particle size 2.8μm: St 70ml, initiator AIBN 2.5g, dispersant PVP 10g, TX-705 3.5g, EtOH 480ml, reaction temperature 70℃, stirring speed 200r / min, after reacting for 1h, add EGDMA 0.5ml, PEI 6.5g, continue to react for 8h and then centrifuge and wash, add 100ml toluene to the obtained PS-EGDMA-amino microsphere solid, stir for 2h, centrifuge, wash twice with methanol, and dry in a vacuum oven to obtain uniform porous microspheres containing amino groups.

[0089] Table 1 Preparation parameters and product parameters of Examples 1 to 12

[0090]

[0091]

[0092] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing porous functional microspheres, comprising the following steps: A) mixing a polymerization monomer, an initiator, a dispersant, a cross-linking agent and a functional monomer in a dispersion medium, reacting to obtain monodispersed functional microspheres; The polymerizable monomer is styrene; The cross-linking agent is one or more of polyethylene glycol diacrylate, ethylene glycol dimethacrylate and trimethylolpropane triacrylate, and the mass of the cross-linking agent is 0.5% to 5% of the mass of the polymerized monomer; The dispersion medium is an alcohol-water mixture; in the alcohol-water mixture, the volume ratio of alcohol to water is 9:1-6:4; The functional monomer is methacrylic acid and / or acrylamide; B) dispersing the monodisperse functional microspheres in a good solvent and stirring to obtain monodisperse porous functional microspheres; The good solvent is toluene and / or tetrahydrofuran; The porous functional microspheres have a hollow structure, a gradient pore structure or a uniform pore structure.

2. The preparation method according to claim 1, characterized in that: The initiator is azobisisobutyronitrile and / or azobisisovaleronitrile; the mass of the initiator is 1% to 4% of the mass of the polymerization monomer.

3. The preparation method according to claim 2, characterized in that: The dispersant is one or more of polyvinyl pyrrolidone, sodium styrene sulfonate, Triton X-100, Triton X-114, Triton X-305, Triton X-405 and Triton X-705; The mass of the dispersant is 2-20 wt % of the mass of the polymerized monomer.

4. The preparation method according to claim 1, characterized in that: The reaction temperature in step A) is 65-80° C., and the reaction time in step A) is 8-12 hours.

5. The preparation method according to claim 1, characterized in that: The stirring time in step B) is 0.5 to 6 hours.

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