CN111849111A - A kind of two-dimensional Janus nanomaterial and preparation method thereof - Google Patents

Abstract

The invention discloses a two-dimensional Janus nanomaterial and a preparation method thereof. The two-dimensional Janus nanomaterial of the present invention is prepared by self-assembling block copolymers by cross-linking on a two-dimensional structure model. Its preparation method includes the following steps: 1) growing metal particles on the surface of silica spheres, then modifying the above-mentioned silica spheres with alkylsilane; then removing the metal particles on the above-mentioned modified silica spheres and load imidazole groups to obtain template A; 2) Mix the block copolymer with the template A, carry out self-assembly in a polar organic solvent, and then add a cross-linking agent for cross-linking reaction to obtain the two-dimensional Janus Nanomaterials. The two-dimensional Janus nanomaterial of the invention has adjustable chemical composition, adjustable thickness and adjustable outer diameter; the preparation method has the advantages of simplicity, low cost, convenient adjustment of microstructure and the like. The invention can realize rapid and batch preparation of Janus materials with multiple potential functionalities whose composition and structure are precisely regulated.

Description

A kind of two-dimensional Janus nanomaterial and preparation method thereof

technical field

The invention relates to a two-dimensional Janus nanomaterial and a preparation method thereof, belonging to the field of macromolecules.

Background technique

Janus originally means the double-faced god of ancient Roman mythology. In 1991, de Gennes first proposed the concept of Janus in the field of polymers to describe particles composed of two materials with different chemical and physical properties (de Gennes, P.G.Soft Matter.Science.1992,256(5056),495 -497). Janus materials with multifunctional characteristics are new materials and have important application prospects in many fields. There are still many problems in the existing methods for preparing 2D Janus nanomaterials. Commonly used pulverization methods for the preparation of 2D flakes (Walther, A.; Andre, X.; Drechsler, M.; Abetz, V.; Mueller, A.H.E. Janus Discs. "Janus Discs", J.Am.Chem.Soc. 2007, 129, 6187-6198.) Although the Janus structure can be realized, the shape and size are difficult to control. Self-assembly method (Deng, R.H.; Liang, F.X.; Zhou, P.; Zhang C.L.; Qu, X.Z., Wang, Q.; Li, J.L.; Zhu, J.T. and Yang, Z.Z. Janus Nanodisc of Diblock Copolymers. 26, 4469-4472.) Although circular Janus nanosheets were obtained, the sizes were not uniform. Common printing methods for preparing two-dimensional ring materials (McLellan, J.M.; Geissler, M.; Xia, Y.N. "EdgeSpreading Lithography and its Application to the Fabrication of Mesoscopic Gold and Silver Rings", J.Am.Chem.Soc.2004,126 , 10830-10831.) High cost. The etching method (Xu, H.; Goedel, W.A. "Mesoscopic Rings by Controlled Wetting of Particle Imprinted Templates", Angew. Chem., Int. Ed. 2003, 42, 4696-4700.) cannot prepare nanoscale rings. Moreover, none of these methods can prepare nanorings with Janus structure, nor can they prepare sheet-like materials.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a two-dimensional Janus nanomaterial and a preparation method thereof. The two-dimensional Janus nanomaterial of the present invention has adjustable chemical composition, adjustable thickness and adjustable outer diameter; The structure is easy to adjust.

The invention provides a two-dimensional Janus nanomaterial, which is prepared by self-assembling a block copolymer on a two-dimensional structure model by cross-linking.

In the above-mentioned two-dimensional Janus nanomaterials, the two-dimensional structure model is disc-shaped or annular;

The particle size of the two-dimensional Janus nanomaterial may be 10-50 nm, preferably 20-30 nm.

In the above two-dimensional Janus nanomaterial, the block copolymer includes polyacrylic acid-polystyrene block copolymer or sodium polystyrene sulfonate-polystyrene block copolymer;

The block ratio of the polyacrylic acid-polystyrene block copolymer may be 1:0.2-12, specifically 1:12, 9:2.3, 9.8:2.3, 1:1 or 1:0.23-12; The block ratio of the sodium polystyrene sulfonate-polystyrene block copolymer may be 1:0.2-12, specifically 9:2, 1:12.

The present invention also provides a method for preparing the above-mentioned two-dimensional Janus nanomaterial, comprising the following steps:

1) growing metal particles on the surface of silica spheres, then modifying the above-mentioned silica spheres with alkylsilane; then removing the metal particles on the above-mentioned modified silica spheres and loading imidazole groups to obtain template A ;

2) Mix the block copolymer with the template A, carry out self-assembly in a polar organic solvent, and then add a cross-linking agent to carry out a cross-linking reaction to obtain the two-dimensional Janus nanomaterial.

In the above preparation method, step 2) further includes the step of removing the template A by fractional centrifugation after the cross-linking reaction. The specific conditions can be heating the reaction to 65°C, stirring the reaction for 120 min, and then fractionating and centrifuging.

In the above preparation method, the cross-linking reaction is carried out using the polar organic solvent to obtain the two-dimensional Janus nanomaterial in a disc shape;

The cross-linking reaction is carried out using a non-polar organic solvent to obtain the circular two-dimensional Janus nanomaterial.

In the above preparation method, the metal particles include at least one of gold particles, silver particles, nickel particles, iron particles and their oxide particles, specifically the oxide particles such as silver nitrate, nickel nitrate, Fe ₃ O ₄ , FeOOH particles;

The mass ratio of the silica spheres to the metal particles may be 1:0.3-1.5, specifically 1:0.9;

The alkylsilane is at least one of n-octyltrimethoxysilane, octadecyltrimethoxysilane, octadecyltriethoxysilane and n-octyltrimethoxysilane, and the alkylsilane is all 1 to 50% of the total mass after the metal particles are grown on the surface of the silica sphere;

removing the metal particles using hydrochloric acid and/or nitric acid;

The loading amount of the imidazole group on the modified silica sphere may be 1-3%.

In the present invention, the alkylsilane-modified silica ball adopts a method known to those skilled in the art.

In the above preparation method, the mass ratio of the template A to the block copolymer may be 1:0.01-0.1, specifically 1:0.05, 1:0.01-0.05, 1:0.05-0.1 or 1:0.05. 0.02～0.08;

The block ratio of the polyacrylic acid-polystyrene block copolymer may be 1:0.2-12, specifically may be 1:12, 9:2.3, 9.8:2.3, 1:1 or 1:0.2-12; The block ratio of the sodium polystyrene sulfonate-polystyrene block copolymer may be 1:0.2-12, specifically 9:2, 1:12.

In the above-mentioned preparation method, the polar organic solvent is selected from at least one of tetrahydrofuran, N,N-dimethylformamide and dimethyl sulfoxide;

The non-polar organic solvent is selected from at least one of n-hexane, n-heptane, n-octane and n-decane;

The crosslinking agent is at least one of 1,6-hexamethylene diisocyanate, 1,8-octane diisocyanate and 1,10-decane diisocyanate.

In the above preparation method, the mass ratio of the template A, the block copolymer and the crosslinking agent is 1:0.01-0.1:0.001-0.1, specifically 1:0.05:0.005, 1:0.05- 0.1: 0.005～0.1, 1: 0.01～0.05: 0.001～0.005 or 1: 0.02～0.08: 0.002～0.075;

In terms of mass percentage, the total solid content of the block copolymer, the template A and the cross-linking agent in the reaction system of the cross-linking reaction may be 0.1-10%, preferably 1-5%;

The conditions of the self-assembly are as follows: the temperature can be 0°C to 50°C, preferably 20°C to 40°C, specifically normal temperature; the time can be 30 to 300 minutes, specifically 120 minutes, 240 minutes, 60 to 120 minutes, or 120 to 240 minutes. ;

The conditions of the crosslinking reaction are as follows: the temperature can be 0°C to 50°C, preferably 20°C to 40°C, specifically normal temperature; the time is 10 to 120 minutes, specifically 60 minutes, 120 minutes or 60 to 120 minutes.

In the present invention, the normal temperature is common knowledge in the art, and is 0°C to 30°C, specifically 25°C.

The present invention also provides the two-dimensional Janus nanomaterial prepared by the above preparation method.

The structure of the two-dimensional Janus nanomaterial is disc-shaped or annular.

The particle size of the two-dimensional Janus nanomaterial is 10-50 nm, preferably 20-30 nm.

The two-dimensional Janus nanomaterial of the invention is used in the fields of catalysis, oil-water separation, water purification and cell identification.

The present invention has the following advantages:

The two-dimensional Janus nanomaterial of the invention has adjustable chemical composition, adjustable thickness and adjustable outer diameter; the preparation method has the advantages of simplicity, low cost, convenient adjustment of microstructure and the like, and the preparation method is uniform in preparation structure and adjustable in microstructure. Methods of Nanomaterials. The invention can realize the rapid and batch preparation of Janus materials with multiple potential functionalities whose composition and structure are precisely regulated. Significance.

Description of drawings

FIG. 1 is the transmission and atomic force microscope images of the two-dimensional Janus nanodisks prepared in Example 4 of the present invention.

FIG. 2 is the transmission and atomic force microscope images of the two-dimensional Janus nanoring prepared in Example 8 of the present invention.

Detailed ways

The experimental methods used in the following examples are conventional methods unless otherwise specified.

The materials, reagents, etc. used in the following examples can be obtained from commercial sources unless otherwise specified.

Embodiment 1, the preparation of template A

Ethanol (40 mL) was added to silica microspheres (0.1 g), ethanol (25 mL) was added to silver nitrate (0.09 g), and the two were mixed at 50°C and stirred for 15 min, then n-butylamine (0.05 mL) was added, and the reaction was performed for 10 min. , washed, and the samples were lyophilized. The above product (0.1 g) was added with dichloromethane (50 mL) and n-octylethoxysilane (0.5 mL), stirred and reacted at room temperature for 6 h, and washed. The above product was added to nitric acid (20 mL) containing 32 wt % water and reacted for 10 min, and then washed with ethanol. The surface of the above product is treated with an imidazolyl silane coupling agent and then washed. The loading amount of imidazole groups on the modified silica spheres is 2.3%, and the sample is freeze-dried. Get template A.

Embodiment 2, the preparation of template A

Ethanol (40 mL) was added to silica microspheres (0.1 g), ethanol (25 mL) was added to nickel nitrate (0.09 g), the two were mixed at 50°C and stirred for 15 min, then n-butylamine (0.05 mL) was added, and the reaction was carried out for 60 min. , washed, and the samples were lyophilized. The above product (0.1 g) was added with chloroform (50 mL) and n-octylmethoxysilane (0.5 mL), stirred and reacted at room temperature for 12 h, and washed. The above product was added to nitric acid (20 mL) containing 32 wt % water and reacted for 10 min, and then washed with ethanol. The surface of the above product is treated with an imidazolyl silane coupling agent and then washed. The loading amount of imidazole groups on the modified silica spheres is 2.4%, and the sample is freeze-dried. Get template A.

Embodiment 3, the preparation of template A

Ethanol (40 mL) was added to silica microspheres (0.1 g), ethanol (25 mL) was added to nickel nitrate (0.09 g), and the two were mixed at 50°C and stirred for 15 min, then n-butylamine (0.05 mL) was added, and the reaction was carried out for 40 min. , washed, and the samples were lyophilized. The above product (0.1 g) was added with chloroform (50 mL) and n-octylmethoxysilane (0.5 mL), stirred and reacted at room temperature for 12 h, and washed. The above product was added to nitric acid (20 mL) containing 32 wt % water and reacted for 10 min, and then washed with ethanol. The surface of the above product was treated with an imidazolyl silane coupling agent and then washed. The loading amount of imidazole groups on the modified silica spheres was 2.9%, and the samples were freeze-dried. Get template A.

Example 4. Preparation of nanodisc Janus material

Tetrahydrofuran (20 mL) was added to the template A (20 mg) prepared in Example 1 of the present invention, polyacrylic acid _1.1k -styrene _12k block copolymer (1 mg) was added, stirred at room temperature (25° C.) for 120 min, and washed by centrifugation. . The reaction product was dispersed in tetrahydrofuran (20 mL), 1,6-hexanediisocyanate (0.1 mL) was added, and the reaction was stirred at room temperature (25° C.) for 120 min, and then washed by centrifugation. The product was dispersed in tetrahydrofuran (20 mL), hydrochloric acid (25 μL) was added, the reaction was heated to 65°C, and the reaction was stirred for 120 min, followed by fractional centrifugation. Dry. As shown in Figure 1, the diameter of the nanodisc Janus material was found to be about 10 nm by transmission electron microscopy, and its height was 1 nm characterized by AFM.

Example 5. Preparation of nanodisc Janus material

Tetrahydrofuran (20 mL) was added to the template A (20 mg) prepared in Example 2 of the present invention, polyacrylic acid _9k -polystyrene _2.3k block copolymer (referred to as PAA _9k -b-PS _2.3k , 1 mg) was added, After stirring at room temperature (25° C.) for 120 min, centrifugal washing was performed. The reaction product was dispersed in tetrahydrofuran (20 mL), 1,6-hexanediisocyanate (0.1 mL) was added, and the reaction was stirred at room temperature (25° C.) for 120 min, and then washed by centrifugation. The product was dispersed in tetrahydrofuran (20 mL), hydrochloric acid (25 μL) was added, the reaction was heated to 65°C, and the reaction was stirred for 120 min, followed by fractional centrifugation. Dry. The diameter of the nanodisc Janus material was found to be about 30 nm by transmission electron microscopy.

Example 6. Preparation of nanodisc Janus material

N,N-dimethylformamide (20 mL) was added to the template A (20 mg) prepared in Example 3 of the present invention, and sodium polystyrene sulfonate _9k -polystyrene _2k block copolymer (PSS for short) was added. _9k -b-PS _2k , 1 mg), stirred at room temperature (25° C.) for 120 min for 240 min, and washed by centrifugation. The reaction product was dispersed in N,N-dimethylformamide (20 mL), 1,8-octane diisocyanate (0.1 mL) was added, and the reaction was stirred at room temperature (25° C.) for 60 min, and then washed by centrifugation. Disperse the product in N,N-dimethylformamide (20mL), add hydrochloric acid (25μL), heat the reaction to 65°C, stir the reaction for 120min, and then fractionate and centrifuge. After low-speed centrifugation, the supernatant contains nanodisc Janus The material was then centrifuged at high speed, and the samples were lyophilized. The diameter of the nanodisc Janus material was found to be about 20 nm by transmission electron microscopy.

Example 7. Preparation of nanodisc Janus material

Tetrahydrofuran (20 mL) was added to the template A (20 mg) prepared in Example 1 of the present invention, polyacrylic acid _9.8k -polystyrene _2.3k block copolymer (1 mg) was added, and after stirring at room temperature (25° C.) for 120 min, Wash by centrifugation. The reaction product was dispersed in tetrahydrofuran (20 mL), 1,6-hexanediisocyanate (0.1 mL) was added, and the reaction was stirred at room temperature (25° C.) for 120 min, and then washed by centrifugation. The product was dispersed in tetrahydrofuran (20 mL), hydrochloric acid (25 μL) was added, the reaction was heated to 65°C, and the reaction was stirred for 120 min, followed by fractional centrifugation. Dry. The diameter of the nanodisc Janus material was found to be about 10 nm by transmission electron microscopy. AFM characterizes its height as 3 nm.

Example 8. Preparation of nano-ring Janus material

Tetrahydrofuran (20 mL) was added to the template A (20 mg) prepared in Example 1 of the present invention, polyacrylic acid _1k -polystyrene _1k block copolymer (referred to as PAA _1k -b-PS _1k , 1 mg) was added, and the room temperature ( 25°C), after stirring for 120 min, centrifugal washing. The reaction product was dispersed in n-hexane (20 mL), 1,6-hexanediisocyanate (0.1 mL) was added, and the reaction was stirred at room temperature (25° C.) for 120 min, and then washed by centrifugation. The product was dispersed in tetrahydrofuran (20 mL), hydrochloric acid (25 μL) was added, the reaction was heated to 65°C, and the reaction was stirred for 120 min, followed by fractionation centrifugation. Dry. As shown in Figure 2, the outer diameter of the nanoring-shaped Janus material was found to be about 10 nm by transmission electron microscopy.

Example 9. Preparation of nano-ring Janus material

N,N-dimethylformamide (20 mL) was added to the template A (20 mg) prepared in Example 2 of the present invention, and sodium polystyrene sulfonate _9k -polystyrene _2k block copolymer (PSS for short) was added. _9k -b-PS _2k , 1 mg), stirred at room temperature for 240 min, and washed by centrifugation. The reaction product was dispersed in n-decane (20 mL), 1,8-octane diisocyanate (0.1 mL) was added, and the reaction was stirred at room temperature for 60 min, and then washed by centrifugation. Disperse the product in N,N-dimethylformamide (20mL), add hydrochloric acid (25μL), heat the reaction to 65°C, stir the reaction for 120min, then fractionate and centrifuge, after low-speed centrifugation, the supernatant contains nano-ring Janus The material was then centrifuged at high speed, and the samples were lyophilized. The outer diameter of the nanoring-shaped Janus material was found to be about 30 nm by transmission electron microscopy.

Example 10. Preparation of nano-ring Janus material

N,N-dimethylformamide (20 mL) was added to the template A (20 mg) prepared in Example 3 of the present invention, and a polystyrene sulfonate sodium _1k -polystyrene _12k block copolymer (PSS for short) was added. _1k -b-PS _12k , 1 mg), stirred at room temperature for 240 min, and washed by centrifugation. The reaction product was dispersed in n-decane (20 mL), 1,8-octane diisocyanate (0.1 mL) was added, and the reaction was stirred at room temperature for 60 min, and then washed by centrifugation. Disperse the product in N,N-dimethylformamide (20mL), add hydrochloric acid (25μL), heat the reaction to 65°C, stir the reaction for 120min, then fractionate and centrifuge, after low-speed centrifugation, the supernatant contains nano-ring Janus The material was then centrifuged at high speed, and the samples were lyophilized. The outer diameter of the nanoring-shaped Janus material was found to be about 20 nm by transmission electron microscopy.

According to the above examples, two-dimensional Janus nanomaterials are prepared by cross-linking the block copolymer in the patch region after confinement self-assembly of the present invention. Adjustable thickness, adjustable outer diameter.

The above are only the preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, without departing from the principles of the present invention, several improvements and modifications can be made. It should be regarded as the protection scope of the present invention.

Claims (10)

1. A two-dimensional Janus nanomaterial, which is characterized in that: the two-dimensional Janus nano material is prepared by self-assembling a block copolymer on a two-dimensional structure model through crosslinking.

2. The two-dimensional Janus nanomaterial as recited in claim 1, wherein: the two-dimensional structure model is disc-shaped or circular;

the particle size of the two-dimensional Janus nano material is 10-50 nm.

3. The two-dimensional Janus nanomaterial as recited in claim 1 or 2, wherein: the block copolymer comprises polyacrylic acid-polystyrene block copolymer or sodium polystyrene sulfonate-polystyrene block copolymer;

The block ratio of the polyacrylic acid-polystyrene block copolymer is 1: 0.2-12; the block ratio of the sodium polystyrene sulfonate-polystyrene block copolymer is 1: 0.2-12.

4. A method of preparing the two-dimensional Janus nanomaterial of any of claims 1-3, comprising the steps of:

1) growing metal particles on the surface of the silicon dioxide ball, and then modifying the silicon dioxide ball by using alkyl silane; removing the metal particles on the modified silicon dioxide spheres and loading imidazole groups to obtain a template A;

2) and mixing the block copolymer with the template A, carrying out self-assembly in a polar organic solvent, and then adding a cross-linking agent for cross-linking reaction to obtain the two-dimensional Janus nano material.

5. The method of claim 4, wherein: the step 2) also comprises a step of removing the template A by fractional centrifugation after the crosslinking reaction.

6. The production method according to claim 4 or 5, characterized in that: when the cross-linking reaction is carried out by adopting the polar organic solvent, the disc-shaped two-dimensional Janus nano material is obtained;

and when the crosslinking reaction is carried out by adopting a nonpolar organic solvent, the annular two-dimensional Janus nano material is obtained.

7. The production method according to any one of claims 4 to 6, characterized in that: the metal particles include at least one of gold particles, silver particles, nickel particles, iron particles, and oxide particles thereof;

the mass ratio of the silicon dioxide balls to the metal particles is 1: 0.3-1.5;

the alkyl silane is at least one of n-octyl trimethoxy silane, octadecyl triethoxy silane and n-octyl trimethoxy silane, and the alkyl silane accounts for 1-50% of the total mass of the silicon dioxide spheres after metal particles grow on the surfaces of the silicon dioxide spheres;

hydrochloric acid and/or nitric acid are adopted for removing the metal particles;

the loading amount of the imidazole groups loaded on the modified silicon dioxide spheres is 1-3%.

8. The production method according to any one of claims 4 to 7: the mass ratio of the template A to the block copolymer is 1: 0.01 to 0.1;

the block ratio of the polyacrylic acid-polystyrene block copolymer is 1: 0.20-12; the block ratio of the sodium polystyrene sulfonate-polystyrene block copolymer is 1: 0.2-12.

9. The production method according to any one of claims 6 to 8: the polar organic solvent is at least one selected from tetrahydrofuran, N-dimethylformamide and dimethyl sulfoxide;

The nonpolar organic solvent is selected from at least one of n-hexane, n-heptane, n-octane and n-decane;

the cross-linking agent is at least one of 1, 6-hexamethylene diisocyanate, 1, 8-octanedionate and 1, 10-decanedionate.

10. The production method according to any one of claims 4 to 6: the mass ratio of the template A, the block copolymer and the cross-linking agent is 1: 0.01-0.1: 0.001 to 0.1;

the total solid content of the block copolymer, the template A and the cross-linking agent in a reaction system of the cross-linking reaction is 0.1-10% by mass percent;

the conditions for the self-assembly are as follows: the temperature is 0-50 ℃; the time is 30-300 min;

the conditions of the crosslinking reaction are as follows: the temperature is 0-50 ℃; the time is 10-120 min.

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