WO2023236352A1

WO2023236352A1 - Amine-compound-modified graphene film and preparation method therefor

Info

Publication number: WO2023236352A1
Application number: PCT/CN2022/113973
Authority: WO
Inventors: 耿凤霞; 张家文
Original assignee: 苏州大学
Priority date: 2022-06-07
Filing date: 2022-08-22
Publication date: 2023-12-14
Also published as: CN115072714B; CN115072714A

Abstract

An amine-compound-modified graphene film and a preparation method therefor. A graphene oxide solution is subjected to film formation to obtain a graphene oxide film, and the graphene oxide film is then sequentially subjected to an amine compound solution treatment and a reduction treatment to obtain an amine-compound-modified graphene film, wherein the amine compound is an aromatic amine compound containing two or more amino groups. A graphene film prepared in the prior art has relatively low mechanical strength; the present method improves the axial stress transfer between connected graphene sheets and the mechanical performance of an assembly, and in particular, the large-area conjugation of graphene sheets can form an expanded π-electron cloud, such that high electron mobility on the graphene sheets is achieved; and a resulting graphene assembly product shows very high mechanical performance, and the film has a tensile strength of 1.70 ± 0.05 GPa, a Young's modulus of 131 ± 12 GPa, and an electric conductivity of 1.0 * 10⁵ S·m^-1.

Description

An amine compound modified graphene film and its preparation method

Technical field

The invention belongs to graphene assembly technology, and specifically relates to an amine compound modified graphene film and a preparation method thereof.

Background technique

Graphene films are widely used, including thermal conductive materials, electrically conductive materials, flexible materials, etc. Its preparation methods include high-temperature graphitization of organic substances such as polyimide, self-assembly of graphene oxide aqueous solution, etc. For self-assembled graphene films, a graphene oxide aqueous solution is generally scraped into a film and then reduced to a graphene film. The prior art provides a graphene composite film, which is formed by stacking multiple graphene sheets; there are pores between the graphene sheets; the surface of the graphene sheets is modified with conductive Polymer; highly conductive graphene is directly assembled into a thin film material with a three-dimensional network structure. The existing technology provides the application of graphene film in the negative electrode of lithium metal battery. The graphene film is introduced as an interlayer to achieve the purpose of regulating the interface between Li metal and organic electrolyte and inhibiting the growth of dendrites, simply and effectively creating a safe and stable battery. Cycled lithium metal anode. The prior art discloses a method for preparing a graphene oxide aqueous solution and a method for preparing a graphene oxide film and a graphene film. The method mainly uses the Hummers method to prepare a graphene oxide hydrosol, and then calculates the mass of the hydrosol, and then adds Water and acid or alkali are prepared into a graphene oxide aqueous solution with controllable concentration and pH value. The graphene oxide aqueous solution is made into a graphene oxide film using a gas-liquid interface self-assembly method, and then HI is used to reduce the graphene oxide film. , thereby producing a graphene film. The mechanical strength of graphene films prepared by existing technology is relatively low.

technical problem

The graphene film provided by the present invention has flexibility and tensile properties. The graphene film of the present invention is used alone or in combination with aromatic amines to construct a three-dimensional structure, to construct a highly conductive, certain flexible graphene three-dimensional network, and to realize the feasibility of the three-dimensional structure of the graphene film. Control and adjustment can improve the dense stacking and slow ion transmission of existing graphene film electrodes, especially solving problems such as poor mechanical properties.

Technical solutions

The present invention adopts the following technical solution: an amine compound modified graphene film, forming a graphene oxide solution into a film to obtain a graphene oxide film, and then sequentially subjecting the graphene oxide film to amine compound solution treatment and reduction treatment to obtain an amine compound Modified graphene film; the amine compound is an aromatic amine compound containing two or more amine groups.

In the present invention, a graphene oxide aqueous solution is used to prepare a graphene oxide film. The specific film forming method is conventional technology, such as blade coating film forming technology; then the graphene oxide film is sequentially soaked in an amine compound aqueous solution for 1 to 300 minutes, and Soak in the reducing agent aqueous solution for 1 to 50 hours and perform routine cleaning to obtain a black amine compound modified graphene film with metallic luster; preferably, soak in the amine compound aqueous solution for 10 to 100 minutes and soak in the reducing agent aqueous solution for 5 to 30 minutes. Hour. The concentration of the graphene oxide aqueous solution is 1-100mg/mL; the concentration of the amine compound aqueous solution is 1-10mM.

In the present invention, the amine compound is phenylamine, substituted phenylamine, diphenylamine, substituted diphenylamine, condensed ring aromatic hydrocarbyl amine or substituted condensed ring aromatic hydrocarbyl amine. The molecular weight of the amine compound is less than 1000 and is a small molecule. Compounds; substituents are halogen, alkyl, heteroatoms, etc. Aromatic amine compounds contain two or more amine groups, such as 2 to 10, preferably 3 to 8 amine groups, and most preferably 4 to 6 amine groups.

In the present invention, the reducing agent is hydroiodic acid, hydrobromic acid, vitamin C, hydrazine hydrate, sodium hydroxide, sodium borohydride, etc. A reducing agent solution is used for chemical reduction, and the temperature of chemical reduction is room temperature.

The invention discloses the application of amine compounds in the preparation of the above-mentioned amine compound modified graphene film, which improves the axial stress transfer between connected graphene sheets and the mechanical properties of the assembly, especially the conjugation of large-area graphene sheets. Extended π electron clouds can be formed, enabling high electron mobility on graphene sheets; and no foreign guest materials are included between the stacked flakes, leading to close stacking of well-aligned graphene flakes that favor π-π interactions. function to further improve mechanical and electrical conductive properties. The invention discloses the application of the above-mentioned amine compound modified graphene film in the preparation of graphene functional materials. The so-called graphene functional materials refer to materials containing graphene films or materials processed by conventional methods based on graphene films. Conventional methods include lamination, bonding, mechanical bonding, etc.; the so-called functions include electrical conductivity, thermal conductivity, antibacterial, flexibility, etc. For example, electrodes, conductive/thermal conductive films, flexible sensing devices, conductive graphene components, thermally conductive graphene components, electromagnetic shielding materials, etc. are prepared based on the amine compound modified graphene film of the present invention.

beneficial effects

In the present invention, the axial stress transmission between connected graphene sheets and the mechanical properties of the components are improved. The conjugation of large-area graphene sheets can form an extended electron cloud covering the entire connection plane, thereby achieving high electron density on the graphene sheets. mobility, and avoids the entrapment of foreign guest molecules between stacked flakes and forms a compact stack of well-aligned graphene flakes, further improving mechanical and electrical properties. The method of the invention is simple and effective. It can be applied to high-performance fibers and films. The obtained graphene assembly products show very high mechanical properties. The tensile strength of the film is 1.70±0.05 GPa and the Young's modulus is 131±12 GPa, the conductivity is 1.0×10 ⁵ S m ^-1 , which is several times that of graphene paper, and there are almost no interconnections between the sheets. Its strength and conductivity are even better than films interconnected by complex connectors. Therefore, the method of assembling graphene of the present invention is expected to be used to produce macroscopic graphene assemblies with mechanical and electrical properties close to those of single graphene.

Description of the drawings

Figure 1 shows GO characterization.

Figure 2 shows the characterization of the graphene assembly film, where g is the actual graphene assembly film of Example 1, h is the microphotograph of the film of Example 1, i is the mechanical properties of the film of Example 1 and the comparative example film, j is the comparative example film microscopic photo.

Figure 3 shows the conductivity test of the graphene assembly film of Example 1 and the graphene assembly film of the comparative example.

Figure 4 shows the dependence of the Raman frequency downward shift on the applied strain, in which (a) Example 1 graphene assembly film, (b) Comparative example film, (c) Comparative example film; the inset (lower left) shows more than 100% Spatial plot of Raman frequency under different strains (μm ² ).

Embodiments of the invention

Hall measurements were performed on thin film samples at room temperature using a Janis superconducting magnet probe system under vacuum (~3×10 ^-8 mbar) conditions. A magnetic field of 0.5 Tesla was applied perpendicular to the sample surface. Electrical data were collected by Keysight B1500A semiconductor parameter analyzer. The tensile strength test uses a commercial mechanical tensile testing system (HY-0350, Shanghai Hengyi Precision Instrument Co., Ltd.) equipped with a precision force detector program with an accuracy of 0.00001 N (Ref. Adv. Mater. 2016, 28, 6449-6456 ). For testing the mechanical properties of the films, the specimens were placed on a rectangular frame and cut into strips 1 mm wide and 10 mm long. Mechanical strength is calculated by dividing the fracture force by the fracture cross-sectional area, and Young's modulus is determined from stress and strain (%). Use software on the tester to read the elongation. There are at least 10 samples in each set of experimental conditions.

Because graphene's single-atom thickness and large area give it a large aspect ratio, graphene sheets can be assembled into macroscopic structures, such as graphene films. The starting point for the synthesis of macroscopic graphene is usually graphite oxide dispersed in a solvent. ene (GO), the film is made from dispersed GO through blade coating technology, and then a graphene-based film is obtained through chemical or thermal reduction. The prior art emphasizes the importance of reducing structural defects and improving the regular arrangement of graphene sheets to enhance the mechanical and electrical properties of graphene fibers. High-temperature annealing can eliminate atomic defects on graphene sheets and promote the formation of graphite crystallites. However, from an economic and ecological perspective, the use of high annealing temperatures is usually undesirable, and the performance of the resulting macrographene is still far below Expected for a single graphene layer. Therefore, it is particularly important to develop new strategies to prepare macroscopic graphene films at near room temperature and further prepare thermally conductive graphene materials with high mechanical properties.

For the first time, this invention uses an amine compound as a modifier to obtain a graphene oxide film at room temperature under a conventional scraping process, which is then modified and chemically reduced to a graphene film, thereby avoiding the problems introduced when assembling a 2D single graphene sheet. Fracture occurs due to internal structural defects, and high tensile strength is achieved under the interaction between the edge of the sheet and the in-plane sheet, overcoming the problem of the upper limit bottleneck of the mechanical properties of existing graphene assembly films, especially avoiding the existing technology to improve mechanics. There is a problem of reducing conductivity due to poor performance, as covalent bonding between prior art graphene sheets often reduces conductivity due to disruption of electron transport by the linker, and requires functional modification to restore it. The method of the present invention is simple and effective, and can be applied to high-performance films. The tensile strength of the graphene film obtained by the method of the present invention is 1.70±0.05 GPa, the Young's modulus is 131±12 GPa, and the electrical conductivity is 1.0×10 ⁵ S m ^-1 , several times that of graphene paper, and there is almost no interconnection between the individual sheets. Its strength and conductivity are even better than those of films interconnected using complex connectors. Therefore, the graphene assembly strategy of the present invention is expected to produce macroscopic graphene assemblies with mechanical and electrical properties approaching those of single graphene.

The raw materials used in the present invention are all commercially available products, and the specific preparation operations and testing methods are conventional techniques. As common sense, amine compounds can be prepared in the form of amine compound salts. The solution concentration is based on the amine compound; amine compound hydrochloride or amine compound sulfate can be selected, such as 3,3'-diaminobenzidine hydrochloride. (1,1'-Biphenyl)-3,3'4,4'-tetraaminetetrahydrochloride (CAS No.:868272-85-9), 1,2,4,5-tetraaminobenzene hydrochloride salt, ethylenediamine hydrochloride, p-phenylenediamine hydrochloride, naphthalenediamine hydrochloride, benzidine hydrochloride, etc.

Expandable graphite (approximately 300 μm) was purchased from Nanjing Pioneer Nanomaterial Technology Co., Ltd.; hydrochloric acid (HCl, 12 mol L ^-1 ), potassium permanganate (KMnO ₄ , ≥99.5%) and sulfuric acid (H ₂ SO ₄ , 98% ) was purchased from Jiangsu Johnson & Johnson Functional Chemical Co., Ltd.; hydrogen peroxide (H ₂ O ₂ , 30%) was purchased from Shanghai Lingfeng Chemical Reagent Co., Ltd.; hydroiodic acid (HI, 57 wt%) was purchased from Adamas Beta; 1,2 ,4,5-tetraaminobenzene hydrochloride was obtained from Shanghai Bidepharmatech Co., Ltd., with the following structural formula: .

Synthesis example: GO nanosheets are prepared according to the existing modified Hummers method. 1g of expandable graphite is maintained at 1000°C for 30 seconds, then added to 60ml of sulfuric acid, heated to 80°C, and then 0.84g of potassium persulfate and 1.24g of pentoxide are added. diphosphorus, then add 40ml sulfuric acid and 3g potassium permanganate for oxidation, and then add 2ml hydrogen peroxide. After the reaction, the product is separated, and then washed with hydrochloric acid and water to obtain graphene oxide (GO) dispersed in water. The base and edges of GO sheets are rich in polar oxygen-containing functional groups, which lead to negative surface charges and form stable aqueous dispersions. The oxygen-containing functional groups are usually hydroxyl groups (C–OH), epoxy groups (C– O–C) and carboxyl (–C(=O)OH). Figure 1 shows the characterization diagram of GO sheets. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) show that the lateral size of GO sheets is mainly between 10-70 μm, and the average thickness is about 1 nm; using X-ray photoelectron spectroscopy (XPS) ) and Fourier transform infrared spectroscopy (FTIR) verified the presence of oxygen-containing groups, and elemental analysis showed that the C:O atomic ratio was 1.15.

Example 1: Preparation of graphene assembly film. For film assembly, GO aqueous solution (10 mg/mL) was prepared using conventional blade-coating film-forming technology at room temperature, and then the GO film was dissolved in 1,2,4,5-tetraaminobenzene hydrochloride aqueous solution (5mM). Soak for 30 minutes, wash with water, soak in HI solution (HI, 25wt%) for 12 hours, and then clean with ethanol to obtain a black graphene assembly film with metallic luster, 4 μm thick, see Figure 2, in the cross-sectional image No voids or holes were observed, whereas micropores were present in the control film.

Comparative example: At room temperature, a GO aqueous solution (10 mg/mL) was prepared using conventional blade-coating film-forming technology. The GO film was then soaked in HI solution for 12 hours, and then cleaned with ethanol to obtain a comparative graphene film.

Control example: At room temperature, a GO aqueous solution (10 mg/mL) was used to prepare a GO film using conventional blade-coating film-forming technology, and then the GO film was dissolved in a calcium chloride ethanol/water (1:3 v/v) solution (5wt%). Soak in HI solution for 30 minutes, wash with water, soak in HI solution for 12 hours, and then wash with ethanol to obtain a control graphene film.

Performance test: The present invention obtains a high-performance film. After preparing a GO film by scraping GO dispersion, the film is simply immersed in an aromatic amine solution to improve the stacking direction and packing density, while significantly improving the mechanical and electrical properties. Referring to i in Figure 2, the mechanical strength of the film of the present invention increased by 4 times, the tensile strength increased from 430 MPa to 1.70 GPa, and the corresponding Young's modulus increased sharply from 26.9 GPa to 131.0 GPa. Although synthesized at room temperature, the excellent modulus is close to that of graphite structure. The measured in-plane conductivity was 1.0×10 ⁵ S m ^-1 (Fig. 3), while the control film had a conductivity of 0.2×10 ⁵ S m ^-1 . After replacing 1,2,4,5-tetraaminobenzene hydrochloride in Example 1 with ethylenediamine hydrochloride as an aliphatic amine in equal molar amounts, the tensile strength of the graphene film obtained is less than 500 MPa. Compared with previously reported films, the film of the present invention has significantly improved mechanical and electrical properties (Table 1).

Table 1 Mechanical properties of the film of the present invention and existing films.

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Table 2 Electrical properties of the film of the present invention and existing films.

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In the in-situ Raman test, the film of the present invention shows complete stress transfer. As the strain increases, it shows a continuous frequency downward shift. When the strain is canceled, it is completely reversed without hysteresis. On the contrary, for Ratios or controls show a clear hysteresis curve, see Figure 4.

Example 2: Preparation of graphene assembly film. For film assembly, GO aqueous solution (20 mg/mL) was prepared using conventional blade coating film forming technology at room temperature, and then the GO film was prepared in 1,2,4,5-tetraaminobenzene hydrochloride aqueous solution (7.5mM). Soak in HI solution (HI, 25wt%) for 30 minutes, wash with water, soak in HI solution (HI, 25wt%) for 10 hours, and then clean with ethanol to obtain a black graphene assembly film with metallic luster. No voids or holes are observed in the cross-sectional image. .

Example 3: Preparation of graphene assembled film. For film assembly, GO aqueous solution (7.5 mg/mL) was prepared using conventional blade coating film-forming technology at room temperature, and then the GO film was prepared in 1,2,4,5-tetraaminobenzene hydrochloride aqueous solution (4mM). Soak in HI solution (HI, 25wt%) for 40 minutes, wash with water, soak in HI solution (HI, 25wt%) for 15 hours, and then clean with ethanol to obtain a black graphene assembly film with metallic luster. No voids or holes are observed in the cross-sectional image. .

Example 4: Preparation of graphene assembled film. For film assembly, GO aqueous solution (10 mg/mL) was prepared using conventional blade-coating film-forming technology at room temperature, and then the GO film was dissolved in 1,2,4,5-tetraaminobenzene hydrochloride aqueous solution (10 mM). Soak for 20 minutes, wash with water, soak in HI solution (HI, 25wt%) for 10 hours, and then clean with ethanol to obtain a black graphene assembly film with metallic luster. No voids or holes are observed in the cross-sectional image.

The tensile strengths of the graphene films obtained in Examples 2 to 4 are all above 1.5 GPa.

Example 5: Preparation of graphene assembled film. For film assembly, a GO aqueous solution (10 mg/mL) was prepared using a conventional blade-coating film-forming technique at room temperature, and then the GO film was dissolved in a 3,3',4,4'-biphenyltetramine solution (5mM). Soak for 30 minutes, wash with water, soak in HI solution (HI, 25wt%) for 10 hours, and then clean with ethanol to obtain a black graphene assembly film with metallic luster. No voids or holes are observed in the cross-sectional image.

Example 6: Preparation of graphene assembly film. For film assembly, GO aqueous solution (10 mg/mL) was prepared using conventional blade-coating film-forming technology at room temperature, and then the GO film was soaked in 3,3'-diaminobenzidine hydrochloride aqueous solution (5 mM) for 30 minutes, washed with water, soaked in HI solution (HI, 25wt%) for 12 hours, and then washed with ethanol to obtain a black graphene assembly film with metallic luster. No voids or holes were observed in the cross-sectional image.

Assembling graphene sheets into high-performance macroscopic films is of great fundamental and technological significance, but the overall performance of reported assemblies to date has been severely limited by structural defects. Innovative assembly chemistries and post-processing have been developed to eliminate stacking disorder and defects such as wrinkling within the sheets, but assembly performance is still limited by poor connections between graphene planes, resulting in much lower performance than those based on individual graphene Expectations of ene properties. The mechanical properties and electronic conductivity of the graphene-based macro-assembled film disclosed in the present invention are significantly improved. In particular, it provides high performance under conditions close to room temperature, overcoming the shortcomings of the existing technology that require high-temperature annealing to achieve good performance. Therefore, The method of the present invention provides a new and effective method for preparing high-performance macroscopic graphene components under optimal technical, economic and ecological conditions.

In summary, the present invention has developed a new method to obtain macroscopic graphene structures with high strength and modulus and excellent electronic conductivity at room temperature. Due to the simplicity and effectiveness of this method, it can be applied For thin film fabrication, this may be of interest for further research into other 2D material assemblies and commercial industrial applications related to high-performance structural materials.

Claims

An amine compound-modified graphene film is formed by forming a graphene oxide solution into a film to obtain a graphene oxide film. It is characterized in that the graphene oxide film is sequentially treated with an amine compound solution and reduced to obtain the amine compound-modified graphite. ene film; the amine compound is an aromatic amine compound containing two or more amine groups.
The amine compound modified graphene film according to claim 1, characterized in that the amine compound is phenylamine, substituted phenylamine, diphenylamine, substituted diphenylamine, condensed ring aromatic hydrocarbyl amine or substituted condensed ring Aromatic amines.
The amine compound modified graphene film according to claim 1, wherein the molecular weight of the amine compound is less than 1,000.
The amine compound modified graphene film according to claim 1, characterized in that the reduction treatment is a chemical reduction treatment.
The preparation method of the amine compound modified graphene film according to claim 1, characterized in that the graphene oxide aqueous solution is used to prepare the graphene oxide film; and then the graphene oxide film is soaked in the amine compound aqueous solution for 1 to 300 minutes, and Soak in the reducing agent aqueous solution for 1 to 50 hours to obtain an amine compound modified graphene film.
The method for preparing an amine compound modified graphene film according to claim 5, characterized by soaking in an amine compound aqueous solution for 10 to 100 minutes and soaking in a reducing agent aqueous solution for 5 to 30 hours.
The method for preparing an amine compound modified graphene film according to claim 5, wherein the concentration of the graphene oxide aqueous solution is 1 to 100 mg/mL; and the concentration of the amine compound aqueous solution is 1 to 10 mM.
The method for preparing an amine compound modified graphene film according to claim 5, wherein the reducing agent includes hydriodic acid, hydrobromic acid, vitamin C, hydrazine hydrate, sodium hydroxide or sodium borohydride.
The use of amine compounds in preparing the amine compound-modified graphene film of claim 1, wherein the amine compound is an aromatic amine compound containing two or more amine groups.
The application of the amine compound modified graphene film according to claim 1 in the preparation of graphene functional materials.