A variable aperture colloidal body and method of making the same

Abstract

The application discloses a kind of colloidal bodies with variable pore size and its preparation method, including nanoparticle modification, amphiphilic nanoparticle preparation and variable pore size colloidal body preparation and other steps, by specific setting to each step, so that the colloidal body prepared finally is stable and the pore size is variable, the hydrophobic polymer chain in the cavity inside colloidal body will produce corresponding collapse and stretch form under water / oil different medium environment, close or expose hole, meet the application requirement in selective medium transmission.

Description

Technical Field

[0001] This invention relates to the field of colloidal materials technology, specifically to a colloidal body with variable pore size and its preparation method. Background Technology

[0002] Colloids are microcapsules constructed from colloidal particles as structural units. As a special type of hollow material, colloids have a porous outer shell and functionalized structural units, and they have broad application prospects in biomedicine, cell transplantation, functional foods, and the petroleum industry.

[0003] The soft template method is currently a common method for preparing colloids. It mainly involves the self-assembly and cross-linking of colloidal particles on the surface of emulsion droplets, and the preparation process is simple. However, the soft template method has drawbacks such as difficulty in controlling the morphology, size, and uniformity of the prepared colloids, and even greater difficulty in introducing functional materials into the cavities of the colloids to form multifunctional composite materials.

[0004] Chinese invention patent publication CN104477990A discloses a method for preparing nano-zirconia colloids. The method uses a soft template method to prepare nano-zirconia colloids with high purity, high specific surface area and good dispersibility. However, due to the simplicity of its preparation process, it cannot form a colloidal body, and its performance cannot be compared with that of a colloidal body. Summary of the Invention

[0005] This invention proposes a colloidal body with variable pore size and its preparation method.

[0006] Specifically, this is achieved through the following technical means:

[0007] A method for preparing a colloidal body with variable pore size, wherein the colloidal body is prepared by template method through two-phase emulsification of amphiphilic composite nanoparticles in water and oil, assembly into micelles at the interface, and cross-linking, and the diameter of the colloidal body is 1-15 μm.

[0008] The pore size of the colloid is generated by the stacking of adjacent composite nanoparticles, and the pore size can be controlled by changing the concentration and / or number of nanoparticles; the minimum pore size of the colloid is generated by the nanoparticles in a hexagonal close-packed form, and the area at the minimum pore size is (0.03~0.05)×d. 2 nm 2 , where d is the diameter of the nanoparticle.

[0009] As a preferred option, the following steps are included:

[0010] (1) Nanoparticle modification: Inorganic nanoparticles with a diameter or equivalent diameter of 10-150 nm are modified by silane ligand exchange method to modify the surface of the inorganic nanoparticles with amino and / or carboxyl groups to form modified nanoparticles.

[0011] (2) Polymer chain synthesis: Active polymer chain solution was prepared by cationic polymerization of boron trifluoride-diethyl ether complex as initiator in ultra-dry dichloromethane solvent.

[0012] (3) Preparation of amphiphilic single-chain nanoparticles: The modified nanoparticles prepared in step (1) are dispersed in ultra-dry dichloromethane to obtain a modified nanoparticle dispersion. Under ultrasonic conditions, the active polymer chain solution prepared in step (2) is slowly added to the modified nanoparticle dispersion. The volume ratio of the added active polymer chain solution to the mass ratio of the modified nanoparticles is (0.9-1) mL: (0.9-1) mg. The ultrasonic treatment is continued and the reaction is carried out for 0.8-1.5 h. Then, solid-liquid separation is performed using a magnet, and the solid is washed to obtain single-chain nanoparticles.

[0013] (4) Preparation of variable pore size colloid: 990-1010 parts by weight of aqueous phase, 98-102 parts by weight of oil phase and 0.8-1.2 parts by weight of single-chain nanoparticles prepared in step (3) are placed together in a container and emulsified to obtain a uniform oil-in-water emulsion; then glacial acetic acid is added to adjust the pH of the aqueous phase to 4.8-5.2, and crosslinking is performed with glutaraldehyde aqueous solution. The amount of glutaraldehyde aqueous solution added is 1.2-1.5:1 of the amount of single-chain nanoparticles. After the dynamic Schiff base bond is formed at room temperature for 4-6 hours, sodium borohydride is used for reduction. The amount of sodium borohydride added is 0.5-1:1 times that of glutaraldehyde aqueous solution to obtain a variable pore size colloid.

[0014] Preferably, in step (1), the inorganic nanoparticles are SiO2 nanoparticles, and the modified nanoparticles obtained in step (1) are specifically SiO2@NH2 nanoparticles. Step (1) specifically involves: in a non-polar solvent, using glacial acetic acid as a catalyst, treating SiO2 nanoparticles with aminosilane to perform silane ligand exchange, wherein the ratio of inorganic nanoparticles: aminosilane: catalyst is 0.02% (m / v): 0.5% (v / v): 0.01% (v / v) of the non-polar solvent volume.

[0015] Preferably, the nonpolar solvent is toluene or n-hexane; the aminosilane is 3-aminopropyltrimethoxysilane and / or 3-aminopropyltriethoxysilane.

[0016] Preferably, in step (2), the active polymer chain solution is an active hydrophobic polymer, specifically one or more of polystyrene and polyolefin; the hydrodynamic diameter of the active hydrophobic polymer is greater than or equal to 80% of the diameter of the inorganic nanoparticles, and the weight-average molecular weight of the active hydrophobic polymer is 3.5 × 10⁻⁶. 1 ~3×10 3 kDa; The ultrasonic conditions described in step (3) are an ultrasonic frequency of 55-62KH (preferably 59KHz) and an ultrasonic temperature of 23-28℃ (preferably 25℃).

[0017] Preferably, the polystyrene or polyolefin is poly(p-methylstyrene) or polyisobutylene.

[0018] Preferably, in step (4), the aqueous phase is water, and the oil phase is dichloromethane, toluene, or sliced ​​paraffin with a melting point of 52-54°C.

[0019] Preferably, in step (4), sliced ​​paraffin wax is used as the oil phase to obtain a uniform oil-in-water emulsion. The emulsification step includes placing the entire container in hot water at 60-70°C for ultrasonic treatment. After the paraffin wax is completely melted, the ultrasonic treatment is stopped, and the heating temperature is maintained at 60-70°C. Then, the obtained mixture is subjected to high-speed shearing using a high-speed shearing machine at a shearing rate of 10000-15000 rpm / min. This high-speed shearing is maintained for 2-4 minutes to prepare an oil-in-water emulsion floating on the water phase.

[0020] Preferably, after obtaining the variable pore size colloidal body in step (4), the obtained variable pore size colloidal body is immersed in n-hexane. The amount of n-hexane added is to ensure that all the colloidal body is submerged. After immersion for 30 to 60 minutes, it is taken out to obtain a variable pore size colloidal body with hollow spheres in which the paraffin has been dissolved.

[0021] A variable-pore size colloidal body is prepared by the above-described preparation method; the hydrophobic polymer chains inside the cavity of the variable-pore size colloidal body can undergo collapse and extension morphology in different media environments such as water and / or oil, closing or exposing the pores, and can be used in selective medium transport.

[0022] The technical effects of this invention are as follows:

[0023] This invention, through the specific steps of nanoparticle modification, active polymer chain synthesis, amphiphilic nanoparticle preparation, and variable-pore-size colloid preparation, achieves the process of preparing colloids with variable pore sizes based on inorganic nanoparticles as the core raw material. The process is rationally designed, and the minimum cross-sectional area of ​​the variable pore size of the prepared colloid is 0.04*d. 2 nm 2The microcapsule structure is reasonable, and the pore size and structure of the microcapsule meet the application requirements in media transmission.

[0024] This invention achieves amphiphilic properties by rationally setting the added materials and parameters during the preparation of amphiphilic nanoparticles (e.g., rationally setting the ultrasonic frequency and the addition conditions of each material), so that the prepared composite nanoparticles are grafted with only a single polymer chain.

[0025] This invention, through the rational setting of parameters such as the additive materials, the conditions for material addition, and the addition ratio during the preparation of variable pore size colloids, allows the pore size of the prepared colloid to change with the concentration of amphiphilic nanoparticles, and to be rationally controlled within the pore size range required by this invention, thus meeting the requirements for media transport.

[0026] This invention, through specific settings of the preparation steps and parameters of variable-pore-size colloids based on single-chain nanoparticles (step 4 of the technical solution of this invention), enables the hydrophobic polymer chains inside the cavity of the prepared colloid to undergo corresponding collapse and extension morphologies under different media environments such as water and oil, thereby closing or exposing the pore size, and enabling its application in selective media transport. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the preparation process of the colloid with variable pore size described in this invention.

[0028] Figure 2 The image is a scanning electron microscope (SEM) image of a colloidal body with variable pore size prepared in Example 1 of this invention.

[0029] Figure 3 Scanning electron microscope (SEM) image of a colloidal body with variable pore size prepared in Example 2 of this invention.

[0030] Figure 4 Transmission electron microscopy (TEM) image of a colloidal body with variable pore size prepared in Example 2 of this invention. Detailed Implementation

[0031] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0032] Example 1

[0033] This embodiment provides a silica gel body with variable pore size according to the present invention, wherein sliced ​​paraffin is used as a template, and the gel body size is approximately 10 μm. A schematic diagram of the preparation process is shown below. Figure 1 As shown, the specific steps include:

[0034] (1) SiO2@NH2 nanoparticles

[0035] The aqueous solution of 12 nm SiO2 nanoparticles was lyophilized for later use. 150 μL of 3-aminopropyltriethoxysilane and 3 μL of acetic acid were added to a 6 mg SiO2 nanoparticle toluene dispersion (30 mL), and the mixture was stirred at room temperature for 24 h. After washing with toluene and centrifugation at high speed, the mixture was lyophilized for later use.

[0036] (2) Synthesis of poly(p-methylstyrene) PMS chain

[0037] 20 μL of boron trifluoride-ethyl ether complex was added to 10 mL of ultra-dry dichloromethane, and 3 mL of p-methylstyrene monomer was added under magnetic stirring. The reaction was carried out at room temperature for 30 min to synthesize PMS polymer chains with a molecular weight of 40.9 kDa. The chain size (hydrodynamic diameter) was comparable to the diameter of SiO2@NH2 particles.

[0038] (3) Preparation of PMS-SiO2@NH2 amphiphilic nanoparticles

[0039] 10 mg SiO2@NH2 was dispersed in 10 mL of ultra-dry dichloromethane. Under ultrasonic conditions, the active PMS chain solution described in step (3) was slowly added, and the mixture was ultrasonically reacted for 1 h. After washing with dichloromethane and centrifugation, the particles were labeled as PMS-SiO2@NH2 particles.

[0040] (4) Preparation of colloids with variable pore size

[0041] 2 mg of the PMS-SiO2@NH2 particles described in step (3) were dispersed in 2 mL of water. 0.2 g of sliced ​​paraffin (melting point 52°C) was added, and the glass bottle was placed in 70°C hot water and sonicated until the paraffin was completely melted. Then, the solution was emulsified using a high-shear emulsifier at a shear rate of 10000 rpm / min, and floated on the upper layer of the aqueous phase. 0.2 mL of glutaraldehyde aqueous solution was added to the emulsion, and the pH of the aqueous phase was adjusted to 5. After dynamic Schiff base bonds were formed, sodium borohydride was used for reduction. Finally, the emulsion was immersed in 5 mL of n-hexane for 30 min, and then removed to obtain a colloidal body with variable pore size. The structure of the prepared colloidal body was characterized using scanning electron microscopy, showing a spherical shape with a size of approximately 10 μm. Figure 2 As shown.

[0042] Example 2

[0043] This embodiment provides a silica gel body with variable pore size according to the present invention, wherein an emulsion droplet is used as a template, and the gel body size is approximately 1 μm. Specifically, it includes the following steps:

[0044] (1) SiO2@NH2 nanoparticles (nanoparticle modification)

[0045] The aqueous solution of 12 nm SiO2 nanoparticles was lyophilized for later use. 150 μL of 3-aminopropyltriethoxysilane and 3 μL of acetic acid were added to a 6 mg SiO2 nanoparticle toluene dispersion (30 mL), and the mixture was stirred at room temperature for 24 h. After washing with toluene and centrifugation at high speed, the mixture was lyophilized for later use.

[0046] (2) Synthesis of poly(p-methylstyrene) PMS chain (polymer chain synthesis)

[0047] 20 μL of boron trifluoride-ethyl ether complex was added to 10 mL of ultra-dry dichloromethane, and 3 mL of p-methylstyrene monomer was added under magnetic stirring. The reaction was carried out at room temperature for 30 min to synthesize PMS polymer chains with a molecular weight of 40.9 kDa. The chain size (hydrodynamic diameter) was comparable to the diameter of SiO2@NH2 particles.

[0048] (3) Preparation of PMS-SiO2@NH2 amphiphilic nanoparticles (preparation of amphiphilic single-chain nanoparticles)

[0049] 10 mg SiO2@NH2 was dispersed in 10 mL of ultra-dry dichloromethane. Under ultrasonic conditions, the active PMS chain solution described in step (3) was slowly added, and the mixture was ultrasonically reacted for 1 h. After washing with dichloromethane and centrifugation, the particles were labeled as PMS-SiO2@NH2 particles.

[0050] (4) Preparation of colloids with variable pore size

[0051] 2 mg of the PMS-SiO2@NH2 particles described in step (3) were dispersed in 2 mL of water, and 0.2 mL of toluene was added. The solution was then ultrasonically emulsified. 0.2 mL of glutaraldehyde aqueous solution was added to the emulsion, and the pH of the aqueous phase was adjusted to 5. After dynamic Schiff base bonds were formed, the emulsion was reduced with sodium borohydride to obtain a colloidal body with variable pore size. The structure of the prepared colloidal body was characterized using scanning electron microscopy and transmission electron microscopy. It exhibited a spherical structure with a size of approximately 1 μm. Figure 3 , 4 As shown.

[0052] Example 3

[0053] This embodiment provides a magnetically responsive colloid with variable aperture as described in this invention, wherein an emulsion droplet soft template is used, and the colloid size is approximately 2 μm. Specifically, it includes the following steps:

[0054] (1) Synthesis of Fe3O4 nanoparticles

[0055] 100 mL of sodium oleate aqueous solution (0.2 M) was mixed with 100 mL of anhydrous ferric chloride aqueous solution (0.2 M), and stirred thoroughly to produce a reddish-brown precipitate. The precipitate was filtered, rinsed with deionized water, and then dried in a vacuum oven. The dried waxy substance was dissolved in 60 mL of ethanol, and 6 mL of oleic acid was added and mixed thoroughly. The mixture was then transferred to a polytetrafluoroethylene high-pressure reactor and reacted at 180 °C for 5 h. After washing with anhydrous ethanol and separation by magnetic magnet, the precipitate was dispersed in toluene for later use; the size was approximately 10 nm.

[0056] (2) Synthesis of Fe3O4@NH2 nanoparticles (nanoparticle modification)

[0057] 0.5% (v / v) 3-aminopropyltriethoxysilane and 0.01% (v / v) acetic acid were added to a 30 mL toluene dispersion of 6 mg Fe3O4 nanoparticles, and the mixture was stirred at room temperature for 24 h. After washing with toluene and magnetic separation, the mixture was freeze-dried for later use.

[0058] (3) Synthesis of polyisobutylene (PIB) chains (polymer chain synthesis)

[0059] 20 μL of boron trifluoride-ethyl ether complex was added to 5 mL of ultra-dry dichloromethane, and 2 mL of isobutylene monomer was added under magnetic stirring. The reaction was carried out at room temperature for 30 min to synthesize polyisobutylene polymer chains with a molecular weight of 34.3 kDa. The chain size (hydrodynamic diameter) was comparable to the diameter of Fe3O4@NH2 particles.

[0060] (4) Preparation of PIB-Fe3O4@NH2 amphiphilic nanoparticles (preparation of amphiphilic single-chain nanoparticles)

[0061] 10 mg Fe3O4@NH2 was dispersed in 10 mL of ultra-dry dichloromethane. Under ultrasonic conditions, the active PVBC chain solution described in step (3) was slowly added, and the reaction was carried out under ultrasonication for 1 h. After washing with dichloromethane and collecting with a magnet, the particles were labeled as PIB-Fe3O4@NH2 particles.

[0062] (5) Preparation of magnetically responsive colloids with variable aperture

[0063] 2 mg of the PIB-Fe3O4@NH2 particles described in step (4) were dispersed in 2 mL of water. 0.2 mL of toluene was added, and the mixture was sonicated for 1 min to obtain a homogeneous emulsion. Under a laser confocal microscope, the emulsion showed a size of approximately 2 μm. 0.2 mL of glutaraldehyde aqueous solution was added to the aqueous phase of the emulsion, and the pH was adjusted to 5. After dynamic Schiff base bonds were formed, the emulsion was reduced with sodium borohydride to obtain a magnetically responsive colloid with variable pore size. The structure of the prepared colloid was characterized using scanning and transmission electron microscopy, revealing hollow spheroids with a size of approximately 2 μm.

[0064] The techniques known in the art involved in this invention have not been described in detail. The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a colloidal body with variable pore size, characterized in that, The colloid is prepared by using a template method to emulsify amphiphilic composite nanoparticles in a water-oil two-phase system, assemble them into micelles at the interface, and then crosslink them. The diameter of the colloid is 1-15 μm. The pore size of a colloid is generated by the stacking of adjacent composite nanoparticles, and the pore size can be controlled by changing the concentration and / or number of nanoparticles. The minimum pore size of the colloid is generated by the hexagonal close-packed nanoparticles, and the area at the minimum pore size is (0.03~0.05)×d. 2 nm 2 , where d is the diameter of the nanoparticle; Specifically, the following steps are included: (1) Nanoparticle modification: Inorganic nanoparticles with a diameter or equivalent diameter of 10~150nm are modified by silane ligand exchange method to modify the surface of inorganic nanoparticles with amino and / or carboxyl groups to form modified nanoparticles. (2) Polymer chain synthesis: Active polymer chain solution was prepared by cationic polymerization of boron trifluoride-diethyl ether complex as initiator in ultra-dry dichloromethane solvent; (3) Preparation of amphiphilic single-chain nanoparticles: The modified nanoparticles prepared in step (1) are dispersed in ultra-dry dichloromethane to obtain a modified nanoparticle dispersion. Under ultrasonic conditions, the active polymer chain solution prepared in step (2) is slowly added to the modified nanoparticle dispersion. The volume ratio of the added active polymer chain solution to the mass ratio of the modified nanoparticles is (0.9~1) mL: (0.9~1) mg. The ultrasonic treatment is continued and the reaction is carried out for 0.8~1.5 h. Then, solid-liquid separation is performed using a magnet, and the solid is washed to obtain single-chain nanoparticles. (4) Preparation of variable pore size colloid: 990-1010 parts by weight of aqueous phase, 98-102 parts by weight of oil phase and 0.8-1.2 parts by weight of single-chain nanoparticles prepared in step (3) are placed together in a container and emulsified to obtain a uniform oil-in-water emulsion; then glacial acetic acid is added to adjust the pH of the aqueous phase to 4.8-5.2, and crosslinking is performed with glutaraldehyde aqueous solution. The amount of glutaraldehyde aqueous solution added is 1.2-1.5 times the amount of single-chain nanoparticles. After the dynamic Schiff base bond is formed after reacting at room temperature for 4-6 hours, sodium borohydride is used for reduction. The amount of sodium borohydride added is 0.5-1 times the amount of glutaraldehyde aqueous solution to obtain a variable pore size colloid.

2. The method for preparing a variable pore size colloid according to claim 1, characterized in that, In step (1), the inorganic nanoparticles are SiO2 nanoparticles, and the modified nanoparticles obtained in step (1) are specifically SiO2@NH2 nanoparticles. Step (1) specifically involves: in a non-polar solvent, using glacial acetic acid as a catalyst, treating SiO2 nanoparticles with aminosilane to perform silane ligand exchange, wherein the inorganic nanoparticles, aminosilane, and catalyst are 0.02% (g / mL), 0.5% (mL / mL), and 0.01% (mL / mL) of the non-polar solvent volume, respectively.

3. The method for preparing a variable pore size colloid according to claim 2, characterized in that, The nonpolar solvent is toluene or n-hexane; the aminosilane is 3-aminopropyltrimethoxysilane and / or 3-aminopropyltriethoxysilane.

4. The method for preparing a variable pore size colloid according to claim 1, characterized in that, In step (2), the active polymer chain solution is an active hydrophobic polymer, specifically one or more of polystyrene and polyolefin; the hydrodynamic diameter of the active hydrophobic polymer is greater than or equal to 80% of the diameter of the inorganic nanoparticles, and the weight-average molecular weight of the active hydrophobic polymer is 3.5 × 10⁻⁶. 1 ~3×10 3 kDa; The ultrasonic conditions described in step (3) are an ultrasonic frequency of 55~62KHz and an ultrasonic temperature of 23~28℃.

5. The method for preparing a variable pore size colloid according to claim 4, characterized in that, The polystyrene and polyolefins mentioned are poly(p-methylstyrene) or polyisobutylene.

6. The method for preparing a variable pore size colloid according to claim 1, characterized in that, In step (4), the aqueous phase is water, and the oil phase is dichloromethane, toluene, or sliced ​​paraffin with a melting point of 52-54°C.

7. The method for preparing a variable pore size colloid according to claim 1, characterized in that, In step (4), a uniform oil-in-water emulsion is obtained by using sliced ​​paraffin as the oil phase. The emulsification step includes placing the entire container in hot water at 60~70℃ for ultrasonic treatment. After the paraffin is completely melted, the ultrasonic treatment is stopped, and the heating temperature is maintained at 60~70℃. Then, the mixture is subjected to high-speed shearing using a high-speed shearing machine at a shearing rate of 10000~15000r / min. The high-speed shearing is maintained for 2~4min to prepare an oil-in-water emulsion floating on the water phase.

8. The method for preparing a variable pore size colloid according to claim 7, characterized in that, After obtaining the variable pore size colloidal body in step (4), the obtained variable pore size colloidal body is immersed in n-hexane. The amount of n-hexane added is to ensure that all the colloidal body is submerged. After immersion for 30~60 minutes, it is taken out to obtain the variable pore size colloidal body of hollow spheres with dissolved paraffin.

9. A colloidal body with variable pore size, characterized in that, The variable-pore colloidal cavity is prepared by any one of the preparation methods described in claims 1 to 8. The hydrophobic polymer chains inside the cavity can collapse and extend in different media environments such as water and / or oil, closing or exposing the pores, and can be used in selective media transport.

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