Polymer nanosheet material and preparation method thereof

Abstract

The invention provides a polymer nanosheet material and a preparation method thereof, and belongs to the technical field of nanosheet material preparation. The preparation method of the polymer nanosheet material comprises the following steps: dispersing block copolymer nanoparticles and MSNRs-NH2 nanoparticles in a solvent, and carrying out a stirring reaction, so as to obtain a block copolymer film coated MSNRs-NH2 nanocomposite material; and etching the composite material to obtain the polymer nanosheet material. The method disclosed by the invention successfully overcomes the technical bottlenecks of difficulty in size control, non-uniform morphology, poor process adaptability and the like caused by the fact that a traditional method depends on a crystal growth mode to prepare the polymer nanosheets, and provides a nanosheet preparation path which is adjustable in size, uniform in size and suitable for various polymer systems.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of nanosheet material preparation, in particular to a kind of polymer nanosheet material and preparation method thereof. BACKGROUND

[0002] As an advanced functional material with ultra-thin two-dimensional structure, polymer nanosheet has shown broad application prospects in the fields of energy, catalysis, biomedical and flexible electronics in recent years. Compared with traditional nanomaterials, polymer nanosheet has high specific surface area, adjustable surface chemical properties and excellent mechanical flexibility, and thus has become a hot spot for interdisciplinary research. At present, its preparation methods mainly include top-down exfoliation method (such as liquid phase exfoliation and chemical exfoliation) and bottom-up synthesis strategy (such as interfacial self-assembly, crystallization-driven self-assembly and polymerization-induced self-assembly, etc.). However, the existing methods still face many challenges: for example, the nanosheets prepared by top-down method are usually of uneven size and limited yield; while the bottom-up method can realize the size and morphology control, but the process is usually complex and the conditions are harsh, making it difficult to realize macro-preparation. In addition, how to realize the precise control of nanosheet size and surface function is still a difficulty in current research. SUMMARY

[0003] Therefore, the present application aims to provide a kind of polymer nanosheet material and preparation method thereof. The present application first prepares a core-shell structure with MSNRs-NH2 nanoparticles as the core and block copolymer nanoparticles as the shell. During the mixing process of the block copolymer nanoparticles and the MSNRs-NH2 nanoparticles, the block copolymer nanoparticles fuse and reassemble on the surface to form a block copolymer film. After removing the MSNRs-NH2, the polymer nanosheet material is obtained.

[0004] In order to achieve the above-mentioned purpose, the present application provides the following technical solutions: One of the technical solutions of the present application is a preparation method of a polymer nanosheet material, comprising the following steps: Disperse the block copolymer nanoparticles and rod-like mesoporous silica (MSNRs-NH2) nanoparticles in a solvent and stir to react, to obtain a block copolymer film coated MSNRs-NH2 nanocomposite; Etch the block copolymer film coated MSNRs-NH2 nanocomposite to obtain the polymer nanosheet material.

[0005] The second technical solution of the present application is a polymer nanosheet material prepared by the above-mentioned preparation method.

[0006] The present application discloses the following technical effects: The present application takes MSNRs-NH2 nanoparticles as a core, and block copolymer nanoparticles as a shell, and the surface of the block nanoparticles is electronegative, which can have electrostatic interaction with the positively charged MSNRs-NH2 nanoparticles, so that the block nanoparticles (block copolymer nanoparticles) can be adsorbed on the surface of the MSNRs-NH2 nanoparticles and fused to reassemble a layer of polymer film, to obtain a composite material with a core-shell structure, and after etching to remove the template MSNRs-NH2, a polymer nanosheet material is prepared, which successfully overcomes the technical bottlenecks of size control difficulty, morphology non-uniformity and poor process adaptability faced by the traditional method of preparing polymer nanosheets by crystallization growth, and provides a nanosheet preparation path which is adjustable in size, uniform in size and suitable for various polymer systems. BRIEF DESCRIPTION OF DRAWINGS

[0007] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0008] Figure 1 The transmission electron microscope picture of the block copolymer nanoparticles (M 92 -B 300 microspheres) prepared for Example 1; Figure 2 The transmission electron microscope picture of the MSNRs-NH2 nanoparticles (1.5:1) prepared for Example 2; Figure 3 The transmission electron microscope picture of the composite material prepared by the MSNRs-NH2 with a length-diameter ratio of 1.5:1 and the M 92 -B 300 nanoparticles in Example 3; Figure 4 The transmission electron microscope picture of the polymer nanosheet material (1.5:1) prepared for Example 4; Figure 5 The transmission electron microscope picture of the polymer nanosheet material (3:1) prepared for Example 4; Figure 6 The transmission electron microscope picture of the polymer nanosheet material (5.5:1) prepared for Example 4. DETAILED DESCRIPTION

[0009] The various exemplary embodiments of the present application will be described in detail below, which should not be considered as a limitation of the present application, but should be understood as a more detailed description of certain aspects, characteristics and embodiments of the present application.

[0010] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. Additionally, for a range of values of, for example, concentrations, solvent amounts, and the like, there are intended to be included in the present application each and every intermediate value of the ranges so stated. For example, a range of from 1 to 10 is intended to include each and every intermediate value between the two values (i.e., 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10). The same applies to other designated ranges of values.

[0011] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application. All documents mentioned in this specification are incorporated herein by reference to disclose and describe the methods and / or materials in connection with which the documents are cited. In case of conflict between the present specification and any document incorporated herein by reference, the present specification will control.

[0012] Various modifications and changes can be made to the specific embodiments of the present application described herein without departing from the scope or spirit of the application. Other embodiments of the application will be apparent to those of ordinary skill in the art from the description and examples presented herein. The description and examples are illustrative of the application and are not intended to limit the scope of the application.

[0013] As used herein, the terms "comprises", "comprising", "includes", "including", "has", "having", "contains", "containing", or variations thereof, are intended to be open-ended terms that mean including, but not limited to.

[0014] The first aspect of the present application provides a preparation method of a high-molecular nanosheet material. First, amphiphilic block copolymer nanoparticles with uniform particle size distribution and good colloidal stability are prepared by a reversible addition-fragmentation chain transfer (RAFT) polymerization method. Then, the block copolymer nanoparticles are fused and assembled on the surface of MSNRs-NH2 nanoparticles to form a high-molecular film with uniform thickness and adjustable hydrophobic segment length by a one-step method, in which the MSNRs-NH2 nanoparticles act as a template and the block copolymer nanoparticles act as a shell. The film forms a uniform polymer film on the plane of the MSNRs-NH2 nanoparticles, but the film is thinner or even absent at the edges. Finally, the template MSNRs-NH2 nanoparticles are removed by etching to obtain the high-molecular nanosheet material.

[0015] In the present application, the particle size of the MSNRs-NH2 nanoparticles is 50-1000 nm, and by adjusting the particle size, high-molecular nanosheet materials with different aspect ratios can be prepared. The thickness of the block copolymer nanoparticles wrapped on the surface of the MSNRs-NH2 nanoparticles is 5-20 nm.

[0016] The preparation method of the high-molecular nanosheet material specifically comprises the following steps: The block copolymer nanoparticles and the MSNRs-NH2 nanoparticles are dispersed in a solvent for stirring reaction to obtain a block copolymer film-coated MSNRs-NH2 nanocomposite. The block copolymer film-coated MSNRs-NH2 nanocomposite is etched to obtain the high-molecular nanosheet material.

[0017] In the preferred embodiment of the present application, the preparation method of the block copolymer nanoparticles is as follows: the monomer, chain transfer agent and initiator are mixed and then subjected to polymerization reaction to obtain the block copolymer nanoparticles.

[0018] In the preferred embodiment of the present application, the monomer includes (methyl) acrylic acid, (methyl) acrylate or benzyl methacrylate (BzMA), and other polymerizable monomers are also applicable to the present application; the chain transfer agent contains a disulfide or trisulfide group; the initiator is an azo initiator; the molar ratio of the chain transfer agent to the initiator is 1-10:1; the molar ratio of the chain transfer agent to the polymerizable monomer is 1:50-500 (further preferably, 1:200-300); the temperature of the polymerization reaction is 20-150 ℃ (further preferably, 60-100 ℃), and the time is 2-48 h (further preferably, 12-24 h).

[0019] Further preferably, the chain transfer agent is macro-CTA; and the azo initiator is azobis (4-cyanopentanoic acid) (i.e., 4,4'-azobis (4-cyanopentanoic acid)), azobis (2-methylimidazole hydrochloride) or azobis (2-methylimidazole).

[0020] In the preferred embodiment of the present application, the solvent used for the polymerization reaction is a mixture of ethanol and methanol in a mass ratio of 2:1; the solid content in the reaction system during the polymerization reaction is 10%; and the polymerization reaction is carried out in an oxygen-free environment.

[0021] In the preferred embodiment of the present application, the preparation method of the MSNRs-NH2 nanoparticles comprises the following steps: The silicon source is added to the co-template solution, and a hydrolysis condensation reaction is carried out under the action of an alkali catalyst to obtain MSNRs nanoparticles; The MSNRs nanoparticles are subjected to surface modification with a silane coupling agent containing an amino group to obtain the MSNRs-NH2 nanoparticles.

[0022] In the preferred embodiment of the present application, the solute in the co-templating agent solution is CTAB (hexadecyltrimethylammonium bromide) and F127 (polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer; Pluronic F127), and the solvent is water; the mass ratio of CTAB and F127 is 0.1-5:1 (further preferably, 1.5-2.5:1).

[0023] In the preferred embodiment of the present application, the silicon source is TEOS (tetraethyl orthosilicate); the base catalyst is ammonia; the molar ratio of CTAB and TEOS is 1:2-8; the mass ratio of the base catalyst and water is 1:0.5-20 (further preferably, 1:10-20); the temperature of the hydrolysis and condensation reaction is 0-80 ℃ (further preferably, 25-35 ℃), and the time is 1-24 h (further preferably, 3-10 h).

[0024] In the preferred embodiment of the present application, after the hydrolysis and condensation reaction, the product is washed. The present application uses ethanol solvent to centrifuge and wash the product multiple times to remove the template agent CTAB, F127 and by-products.

[0025] In the preferred embodiment of the present application, the amino-containing silane coupling agent is APTES (3-aminopropyltriethoxysilane); the mass ratio of the amino-containing silane coupling agent and the MSNRs nanoparticles is 0.5-2:1.

[0026] In the preferred embodiment of the present application, the solvent is ethanol, and the mass ratio of the block copolymer nanoparticles, MSNRs-NH2 nanoparticles and ethanol is 0.5-2:1:5-20; the temperature of the stirring reaction is 40-120 ℃, the time is 6-48 h (further preferably, 12-24 h), and the stirring speed is 60-650 rpm.

[0027] In the present application, when the block copolymer nanoparticles and the MSNRs-NH2 nanoparticles are dispersed in the solvent for stirring reaction, the block copolymer nanoparticles and the MSNRs-NH2 nanoparticles are first dispersed in ethanol solution, respectively, and then the ethanol solution of the block copolymer nanoparticles and the ethanol solution of the MSNRs-NH2 nanoparticles are mixed and stirred.

[0028] In a preferred embodiment of the present invention, the etching agent used to etch the block copolymer film-coated MSNRs-NH2 nanocomposite material is an HF (hydrofluoric acid) solution, a weak acid solution, or a weak alkali solution; the concentration of the hydrofluoric acid solution, the weak acid solution, and the weak alkali solution is 0.5-5 wt%; the mass ratio of the block copolymer film-coated MSNRs-NH2 nanocomposite material to HF in the hydrofluoric acid solution is 5-50:3; and the mass ratio of the block copolymer film-coated MSNRs-NH2 nanocomposite material to the solute in the weak acid or weak alkali solution is 5-50:3.

[0029] A second aspect of the present invention provides a polymer nanosheet material prepared by the above-described preparation method.

[0030] The polymer nanosheets provided by this invention have a length of 50–1000 nm, a width of 20–500 nm, and a thickness of 5–20 nm.

[0031] Unless otherwise specified, the technical solutions described in this invention are all conventional solutions in the field, and the reagents or raw materials used are all purchased from commercial channels or are publicly available unless otherwise specified.

[0032] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0033] Example 1 The preparation process of block copolymer nanoparticles is as follows: With M 92 -B 300 For example, 163.9 mg of poly(methacrylic acid) 92 Macromolecular chain transfer agent (PMAA) 92 1057.2 mg of macro-CTA, benzyl methacrylate (BzMA), and 1.12 mg of 4,4'-azobis(4-cyanopentanoic acid) were added to a round-bottom flask containing 10.66 g of a mixed solvent of ethanol and methanol (ethanol to methanol mass ratio of 2:1). The mixture was purged with nitrogen for 20 min in an ice-water bath to remove oxygen, and then reacted in a 70°C oil bath for 24 h to obtain amphiphilic block copolymer nanoparticles of poly(methacrylic acid). 92 - Poly(benzyl methacrylate) 300 denoted as M 92 -B 300 Microspheres, M 92 -B 300 Transmission microscope image as shown Figure 1 As shown.

[0034] Example 2 The preparation process of MSNRs-NH2 nanoparticles is as follows: As an example of MSNRs-NH2nanoparticles with aspect ratio of 1.5:1, CTAB (728 mg) was first dissolved in water (50 g), then F127 (336 mg) was dissolved in water (14 g), followed by the addition of ammonia solution (60 mL), and then TEOS (2.2 g) was added dropwise. The reaction was carried out at 25°C and a rotation speed of 350 rpm for 3 h. After the reaction, the unreacted raw materials and solvents were removed by washing and centrifuging with ethanol solvent, and the MSNRs nanoparticles were collected. Then 2.5 g of MSNRs nanoparticles were uniformly dispersed in 20 g of ethanol and added to a 100 mL round-bottom flask. Under stirring, 4.5 g of APTES and 1.0 mL of ammonia water were added to the above mixture. The reaction system was sealed and placed in a preheated oil bath at 80°C and stirred for 12 h. After the reaction was completed, the amino-functionalized MSNRs nanoparticles were collected by centrifugation with ethanol and washed with water three times. Then, the MSNRs-NH2was collected by centrifugation with DMF three times, and the final product was soaked in 10 mL of DMF for use. The transmission microscope image of the MSNRs-NH2nanoparticles is shown in FIG. 1. Figure 2

[0035] By adjusting the raw material formula and reaction parameters, MSNRs-NH2nanoparticles with different aspect ratios can be prepared. The synthesis scheme of MSNRs-NH2with different aspect ratios is shown in Table 1 below.

[0036] Table 1 Synthesis formula and basic characterization of MSNRs-NH2with different aspect ratios

[0037] Example 3 The preparation process of the block copolymer film-coated MSNRs-NH2composite material (1.5:1) is as follows: Take 15 mg of MSNRs-NH2(L / D = 1.5:1) and disperse it in 4 g of ethanol, then take 15 mg of M 92 -B 300 The nanoparticles are dispersed in 4 g of ethanol, and then the two dispersions are mixed uniformly. The reaction is carried out in an oil bath at 70°C with a stirring speed of 150 rpm for 24 h to obtain the block copolymer film-coated MSNRs-NH2nanocomposite material (1.5:1).

[0038] The preparation of the block copolymer film-coated MSNRs-NH2composite material (3:1) is the same as that of the block copolymer film-coated MSNRs-NH2composite material (1.5:1), except that the MSNRs-NH2with L / D = 1.5:1 is replaced by MSNRs-NH2with L / D = 3:1.

[0039] ​The preparation of the block copolymer film-coated MSNRs-NH2 composite material (5.5:1) was the same as that of the block copolymer film-coated MSNRs-NH2 composite material (1.5:1), except that the MSNRs-NH2 with L / D = 1.5:1 was replaced by the MSNRs-NH2 with L / D = 5.5:1.

[0040] The preparation of the block copolymer film-coated MSNRs-NH2 composite material (8:1) was the same as that of the block copolymer film-coated MSNRs-NH2 composite material (1.5:1), except that the MSNRs-NH2 with L / D = 1.5:1 was replaced by the MSNRs-NH2 with L / D = 8:1.

[0041] Figure 3 To prepare the block copolymer film-coated MSNRs-NH2 composite material (8:1) from the MSNRs-NH2 with L / D = 1.5:1 and the block copolymer film-coated MSNRs-NH2 composite material (1.5:1) obtained in Example 3, the following steps were taken: 92 -B 300 Transmission electron microscope image of the composite material prepared from the nanoparticles.

[0042] Example 4 The preparation of the block copolymer film-coated MSNRs-NH2 composite material (8:1) was the same as that of the block copolymer film-coated MSNRs-NH2 composite material (1.5:1), except that the MSNRs-NH2 with L / D = 1.5:1 was replaced by the MSNRs-NH2 with L / D = 8:1. The block copolymer film-coated MSNRs-NH2 composite material (1.5:1) obtained in Example 3 was dispersed in 5 mL of water, and then 0.3 mL (5 wt%) of an HF solution was added thereto. After standing for 12 h, centrifugation was performed to obtain the M 92 -B 300 The block copolymer film-coated MSNRs-NH2 composite material (1.5:1).

[0043] The preparation of the block copolymer film-coated MSNRs-NH2 composite material (8:1) was the same as that of the block copolymer film-coated MSNRs-NH2 composite material (1.5:1), except that the MSNRs-NH2 with L / D = 1.5:1 was replaced by the MSNRs-NH2 with L / D = 8:1.

[0044] The preparation of the block copolymer film-coated MSNRs-NH2 composite material (8:1) was the same as that of the block copolymer film-coated MSNRs-NH2 composite material (1.5:1), except that the MSNRs-NH2 with L / D = 1.5:1 was replaced by the MSNRs-NH2 with L / D = 8:1.

[0045] The preparation of the block copolymer film-coated MSNRs-NH2 composite material (8:1) was the same as that of the block copolymer film-coated MSNRs-NH2 composite material (1.5:1), except that the MSNRs-NH2 with L / D = 1.5:1 was replaced by the MSNRs-NH2 with L / D = 8:1.

[0046] Figure 4 A transmission electron microscope picture of a high polymer nanosheet material (1.5:1), Figure 5 A transmission electron microscope picture of a high polymer nanosheet material (3:1), Figure 6 A transmission electron microscope picture of a high polymer nanosheet material (5.5:1). As can be seen from the above pictures, the high polymer nanosheet prepared by the present application has uniform morphology and adjustable size.

[0047] The above only describes the preferred embodiments of the present application, and it should be noted that, for those skilled in the art, several improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A method for preparing a high molecular nanosheet material, characterized by, The method comprises the following steps: The block copolymer nanoparticles and the rod-like mesoporous silica nanoparticles are dispersed in a solvent for stirring reaction to obtain a block copolymer film-coated MSNRs-NH2 nanocomposite material; The block copolymer film-coated MSNRs-NH2 nanocomposite material is etched to obtain the polymer nanosheet material.

2. The production method according to claim 1, characterized by, The block copolymer nanoparticles are prepared by mixing monomers, chain transfer agents and initiators for polymerization reaction.

3. The production method according to claim 2, characterized by, The monomers include (methyl) acrylic acid, (methyl) acrylate or benzyl methacrylate; the chain transfer agent contains a disulfide or trisulfide lipid group; the initiator is an azo initiator; the molar ratio of the chain transfer agent to the initiator is 1-10:1; the molar ratio of the chain transfer agent to the polymerized monomers is 1:50-500; the polymerization reaction is carried out at a temperature of 20-150 ℃ for 2-48 h.

4. The production method according to claim 1, characterized by, The method for preparing the MSNRs-NH2 nanoparticles comprises the following steps: A silicon source is added to a co-template solution, and a hydrolysis condensation reaction is carried out under the action of an alkali catalyst to obtain MSNRs nanoparticles; The MSNRs nanoparticles are surface-modified by using an amino-containing silane coupling agent to obtain the MSNRs-NH2 nanoparticles.

5. The preparation method according to claim 4, characterized in that, The solute in the co-template solution is CTAB and F127, and the solvent is water; the mass ratio of the CTAB to the F127 is 0.1-5:

1.

6. The production method according to claim 5, wherein The silicon source is TEOS; the alkali catalyst is ammonia water; the molar ratio of the CTAB to the TEOS is 1:2-8; the mass ratio of the alkali catalyst to water is 1:0.5-20; the hydrolysis condensation reaction is carried out at a temperature of 0-80 ℃ for 1-24 h.

7. The preparation method according to claim 4, characterized in that, The amino-containing silane coupling agent is APTES; the mass ratio of the amino-containing silane coupling agent to the MSNRs nanoparticles is 0.5-2:

1.

8. The method of claim 1, wherein, The solvent is ethanol, and the mass ratio of the block copolymer nanoparticles, the MSNRs-NH2 nanoparticles and the ethanol is 0.5-2:1:5-20; the stirring reaction is carried out at a temperature of 40-120 ℃ for 6-48 h, and the stirring speed is 60-650 rpm.

9. The method of claim 1, wherein, The etchant used for etching the block copolymer film-coated MSNRs-NH2 nanocomposite material is a hydrofluoric acid solution, a weak acid solution or a weak alkali solution.

10. A polymer nanosheet material prepared by the preparation method of any one of claims 1-9.

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