Anisotropic Conductive Nanocomposite Material, Preparation Method Thereof and Application Thereof

Abstract

The present invention provides an anisotropic conductive nanocomposite material, a preparation method and an application thereof, belonging to the technical field of conductive materials. The preparation method of the anisotropic conductive nanocomposite material includes: applying a first mixed solution containing metal ions and an oxidant on a substrate with a lyophilic surface to form a liquid film on the lyophilic surface; pouring a second mixed solution formed by uniformly mixing a conductive polymer monomer and a two-dimensional nanosheet dispersion liquid on the surface of the liquid film and standing for a period of time. Among them, the two-dimensional nanosheets are super-spread on the surface of the liquid film and form nano-confined spaces between adjacent two-dimensional nanosheets. In the nano-confined spaces, the conductive polymer monomer and the oxidant undergo an oxidation polymerization reaction to obtain a composite film; drying the composite film to obtain the anisotropic conductive nanocomposite material.

Description

Technical Field

[0001] The present invention belongs to the technical field of conductive materials, and particularly relates to an anisotropic conductive nanocomposite material, a preparation method thereof, and an application thereof. Background Art

[0002] Conducting Polymers refer to polymers with good conductivity. Common conducting polymers include polyaniline (PANI), polypyrrole (PPy), poly(3,4-ethylenedioxythiophene) (PEDOT), etc. Compared with traditional metal conductors, conducting polymers not only have a lighter weight and good flexibility, but are also easy to process and form, and are suitable for various electronic and optoelectronic application fields. With the development of flexible electronics, wearable devices, and intelligent materials, the importance of anisotropic conducting polymers has become increasingly prominent because they can meet the stringent requirements for material functionality and performance in these frontier fields. In some applications, such as sensors and flexible circuits, the conductivity of the conducting polymer material in different directions must meet different standards to meet specific working conditions, but how to achieve different conductivities in different directions for the conducting polymer material remains to be studied. Summary of the Invention

[0003] In view of the above technical problems, the present invention provides an anisotropic conductive nanocomposite material, a preparation method thereof, and an application thereof, in order to at least partially solve the above technical problems. Thus, the specific technical solutions provided by the present invention are as follows.

[0004] As a first aspect of the present invention, a preparation method of an anisotropic conductive nanocomposite material is provided, including: applying a first mixed solution containing metal ions and an oxidant onto a substrate with a lyophilic surface to form a liquid film on the lyophilic surface; pouring a second mixed solution formed by uniformly mixing a conducting polymer monomer and a two-dimensional nanosheet dispersion onto the surface of the liquid film and standing for a period of time. Among them, the two-dimensional nanosheets super-spread on the liquid film surface and form nano-confined spaces between adjacent two-dimensional nanosheets. Inside the nano-confined spaces, the conducting polymer monomer and the oxidant undergo an oxidative polymerization reaction to obtain a composite film; drying the composite film to obtain the anisotropic conductive nanocomposite material.

[0005] As a second aspect of the present invention, an anisotropic conductive nanocomposite material prepared by using the above method is provided.

[0006] As a third aspect of the present invention, an application of the anisotropic conductive nanocomposite material in electronic devices is provided.

[0007] In the embodiments of the present invention, a nano-confined space is formed by the super-spreading of two-dimensional nanosheets on the surface of a liquid film, enabling the oxidative polymerization reaction of conductive polymer monomers therein. This special structure is conducive to the formation of anisotropic conductive channels. Meanwhile, the reaction environment within the nano-confined space is relatively stable and uniform, facilitating the uniform polymerization of conductive polymer monomers between the two-dimensional nanosheets, thereby enabling the finally obtained anisotropic conductive nanocomposite material (hereinafter referred to as the composite material) to have good uniformity at the nanoscale. The introduction of two-dimensional nanosheets not only contributes to the conductive performance but also enhances the mechanical properties of the composite material. The composite structure formed by the two-dimensional nanosheets and the conductive polymer monomers can improve the overall strength and toughness of the composite material, enabling the composite material to better withstand external forces and environmental changes during practical applications, being less prone to cracking or damage, and improving the stability and reliability of the composite material. The preparation method of the anisotropic conductive nanocomposite material provided by the present invention mainly includes operations such as mixing solutions, pouring, and standing throughout the preparation process. It does not require complex equipment and advanced technologies, is easy to implement and control, reduces the preparation cost and technical threshold, and is conducive to large-scale production and application. The composite material is directly formed by reaction on the liquid film surface of the substrate without additional complex assembly or transfer processes, reducing problems such as impurity introduction and structural damage that may be brought about by intermediate links, and being conducive to maintaining the integrity and performance of the composite material. At the same time, the in-situ generation method also improves the preparation efficiency and shortens the preparation cycle. Description of the Drawings

[0008] Figure 1 It is a flow chart of the preparation method of the anisotropic conductive nanocomposite material in the embodiments of the present invention;

[0009] Figure 2 It is a preparation flow chart of the anisotropic conductive nanocomposite material in Embodiment 1 of the present invention;

[0010] Figure 3 It is a scanning electron microscope image of the anisotropic conductive nanocomposite material in Embodiment 1 of the present invention at a magnification of 5000×;

[0011] Figure 4 It is a scanning electron microscope image of the anisotropic conductive nanocomposite material in Embodiment 1 of the present invention at a magnification of 10000×;

[0012] Figure 5 It is a transmission electron microscope image of the anisotropic conductive nanocomposite material in Embodiment 1 of the present invention;

[0013] Figure 6 It is an X-ray diffraction pattern of the anisotropic conductive nanocomposite material in Embodiment 1 of the present invention;

[0014] Figure 7X-ray diffraction pattern of the anisotropic conductive nanocomposite material in Embodiment 5 of the present invention;

[0015] Figure 8 Schematic diagram of the conductivity test in the horizontal direction in the embodiment of the present invention;

[0016] Figure 9 Schematic diagram of the conductivity test in the vertical direction in the embodiment of the present invention.

[0017] Explanation of reference numerals:

[0018] 1 - liquid film; 2 - oxidant; 3 - metal ion; 4 - conductive polymer monomer; 5 - two-dimensional nanosheet. Detailed implementation manners

[0019] To make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to specific embodiments and the accompanying drawings.

[0020] The anisotropic conductive properties of conductive polymers can be achieved through the arrangement, orientation or doping of materials, so that composite materials with specific conductive properties can be designed. This functionality provides new opportunities for the development of adaptive and multifunctional materials. However, the conductive mechanism of anisotropic conductive materials still needs to be further studied, especially how to optimize the structure and composition of materials to enhance their anisotropy.

[0021] Based on this, the present invention provides an anisotropic conductive nanocomposite material, its preparation method and application. Using a super-spreading strategy, a conductive polymer monomer is mixed with a two-dimensional nanosheet dispersion liquid and super-spread on a substrate with a lyophilic surface soaked in a metal ion and oxidant solution, and a nano-confined space is formed between adjacent two-dimensional nanosheets. The conductive polymer monomer undergoes chemical oxidative polymerization with the oxidant in the nano-confined space, thereby obtaining an anisotropic conductive nanocomposite material.

[0022] Figure 1 Flowchart of the preparation method of the anisotropic conductive nanocomposite material in the embodiment of the present invention.

[0023] As a first aspect of the present invention, a preparation method of an anisotropic conductive nanocomposite material is provided, as Figure 1 shown, including steps S1 - S3.

[0024] S1: Apply a first mixed solution containing metal ions and an oxidant on a substrate with a lyophilic surface to form a liquid film on the lyophilic surface.

[0025] S2: Pour the second mixed solution formed by uniformly mixing the conductive polymer monomer and the two-dimensional nanosheet dispersion onto the surface of the liquid film and let it stand for a period of time. Among them, the two-dimensional nanosheets are super-spread on the surface of the liquid film and form nano-confined spaces between adjacent two-dimensional nanosheets. Inside the nano-confined spaces, the conductive polymer monomer undergoes an oxidative polymerization reaction with the oxidant to obtain a composite film.

[0026] S3: Dry the composite film to obtain an anisotropic conductive nanocomposite.

[0027] In the embodiments of the present invention, the nano-confined spaces are formed by the super-spreading of the two-dimensional nanosheets on the surface of the liquid film, enabling the conductive polymer monomer to undergo an oxidative polymerization reaction therein. This special structure is conducive to the formation of anisotropic conductive channels. At the same time, the reaction environment inside the nano-confined spaces is relatively stable and uniform, which is conducive to the uniform polymerization of the conductive polymer monomer between the two-dimensional nanosheets, so that the finally obtained composite material has good uniformity at the nanoscale. The introduction of the two-dimensional nanosheets not only contributes to the electrical conductivity but also can enhance the mechanical properties of the composite material. The composite structure formed by the two-dimensional nanosheets and the conductive polymer monomer can improve the overall strength and toughness of the composite material, enabling the composite material to better withstand external forces and environmental changes during practical applications, not easily break or be damaged, and improving the stability and reliability of the composite material. The preparation method of the anisotropic conductive nanocomposite provided by the present invention mainly includes operations such as mixing solutions, pouring, and standing throughout the preparation process. It does not require complex equipment and advanced technologies, is easy to implement and control, reduces the preparation cost and technical threshold, and is conducive to large-scale production and application. Reacting directly on the surface of the liquid film on the substrate to generate the composite material without an additional complex assembly or transfer process reduces problems such as impurity introduction and structural damage that may be brought by intermediate links, and is conducive to maintaining the integrity and performance of the composite material. At the same time, the in-situ generation method also improves the preparation efficiency and shortens the preparation cycle.

[0028] According to the embodiments of the present invention, the super-spreading of the two-dimensional nanosheets on the surface of the liquid film and the formation of nano-confined spaces between adjacent two-dimensional nanosheets include: the two-dimensional nanosheets are super-spread on the surface of the liquid film and are oriented and arranged in a first direction, and then metal ions crosslink and cure with the two-dimensional nanosheets to form nano-confined spaces between adjacent two-dimensional nanosheets in a second direction; wherein, the first direction is parallel to the substrate, and the second direction is perpendicular to the substrate. The two-dimensional nanosheets quickly spread out on the surface of the liquid film at an extremely fast speed (the required time is less than or equal to 2 s) and with an extremely low contact angle (approaching 0), quickly covering the surface of the liquid film and forming a state with uniform distribution and orderly arrangement. The crosslinking and curing effect of the metal ions and the two-dimensional nanosheets enhances the binding force between the two-dimensional nanosheets and makes the structure of the composite material more stable.

[0029] According to an embodiment of the present invention, the metal ion is selected from at least one of iron ions, calcium ions, and aluminum ions. Iron ions, calcium ions, and aluminum ions all have multiple coordination sites, which can cross-link with the functional groups on the surface of the two-dimensional nanosheets, so that the two-dimensional nanosheets form a stable nanoconfined space in the second direction. Different metal ions can give different properties to the composite material. Iron ions have certain magnetism, and the introduction of iron ions can make the composite material have certain magnetic response performance, which can be applied to the field of magnetic control; calcium ions have biocompatibility, and the introduction of calcium ions in composite materials used in the biomedical field helps to improve the compatibility of materials with biological tissues; aluminum ions can improve the mechanical strength of materials, making composite materials more durable.

[0030] According to an embodiment of the present invention, the oxidant is selected from at least one of hydrogen peroxide, dichromate, persulfate, and ferric chloride. The oxidant can provide an oxidizing environment to initiate an oxidative polymerization reaction of the conductive polymer monomer. Different oxidants have different oxidizing abilities and reactivity, and the degree of polymerization of the conductive polymer monomer can be accurately controlled by selecting a suitable oxidant and controlling its dosage.

[0031] According to an embodiment of the present invention, the concentration of metal ions in the first mixed solution is 0.2-3 mol / L. Within this concentration range, it is possible to ensure that there are enough metal ions to crosslink with the two-dimensional nanosheets. When the metal ion concentration is too low, there are insufficient crosslinking sites and insufficient connection between the two-dimensional nanosheets, which will lead to instability of the nanoconfined space structure and affect the performance of the composite material; and when the metal ion concentration is too high, metal ion aggregation will occur, which will destroy the orderly arrangement of the two-dimensional nanosheets and the uniformity of the nanoconfined space.

[0032] According to an embodiment of the present invention, the conductive polymer monomer is selected from at least one of aniline (An), pyrrole (Py), and 3,4-ethylenedioxythiophene (EDOT). Different conductive polymer monomers give different functional properties to the composite material. Polyaniline has good acid sensitivity and redox properties and can be used to prepare functional devices such as sensors; polypyrrole shows good biocompatibility in the biomedical field and can be applied to bioelectronic devices; poly (3,4-ethylenedioxythiophene) has a low electrochemical impedance and has advantages in the fields of electrochemical energy storage.

[0033] According to an embodiment of the present invention, the two-dimensional nanosheets are selected from at least one of montmorillonite (MMT) nanosheets, graphene oxide (GO) nanosheets, and MXene nanosheets. Montmorillonite nanosheets have high mechanical strength and modulus, which can effectively enhance the mechanical properties of the composite material, improve the tensile and bending resistance of the composite material, and make the composite material more durable. Graphene oxide nanosheets have excellent mechanical properties, and their two-dimensional sheet-like structure can play a role in enhancing the skeleton in the composite material, improving the overall strength and toughness of the composite material, and at the same time improving the wear resistance of the composite material. MXene nanosheets have good mechanical properties and flexibility, which can make the composite material have better flexibility and processability while maintaining a certain strength, and are suitable for fields such as flexible electronic devices.

[0034] According to an embodiment of the present invention, the concentration of the two-dimensional nanosheets in the second mixed solution is 1-40 mg / mL to ensure the formation of a uniform and appropriately dense two-dimensional nanosheet layer on the liquid film surface, and a stable and appropriately sized nano-confined space can be formed between adjacent two-dimensional nanosheets. This nano-confined space is conducive to the orderly polymerization of conductive polymer monomers therein to form a regular structure, thereby improving the anisotropy of the composite material. When the concentration of the two-dimensional nanosheets is too low, the interaction between the two-dimensional nanosheets is weak, and an effective nano-confined space and a stable network structure cannot be formed, resulting in insufficient improvement of the mechanical properties, electrical conductivity, etc. of the composite material; while when the concentration is too high, the two-dimensional nanosheets will agglomerate, destroying the uniformity and regularity of the nano-confined space and also affecting the performance of the composite material. When the two-dimensional nanosheets are montmorillonite nanosheets, the mass fraction of the montmorillonite nanosheets is preferably 1-4 wt%; when the two-dimensional nanosheets are graphene oxide nanosheets, the concentration of the graphene oxide nanosheets is preferably 1-3 mg / mL; when the two-dimensional nanosheets are MXene nanosheets, the concentration of the MXene nanosheets is preferably 2-6 mg / mL.

[0035] According to an embodiment of the present invention, the mass ratio of the conductive polymer monomer to the two-dimensional nanosheets is 1-100:1. A suitable mass ratio helps to exert the synergistic effect of the conductive polymer monomer and the two-dimensional nanosheets. The two-dimensional nanosheets provide a high specific surface area support platform for the conductive polymer monomer, which is conducive to the growth and orientation arrangement of the conductive polymer monomer, thereby improving the electrical conductivity and stability of the composite material; at the same time, the conductive polymer monomer can also enhance the binding force between the two-dimensional nanosheets and improve the mechanical properties of the composite material. By adjusting the mass ratio, the functional characteristics of the composite material can be regulated. When it is necessary to enhance the electrical conductivity of the composite material, the proportion of the conductive polymer monomer can be appropriately increased; when higher requirements are placed on the mechanical properties or barrier properties of the composite material, the proportion of the two-dimensional nanosheets can be relatively increased. This controllability enables the composite material to be customized according to different application scenarios and requirements.

[0036] According to an embodiment of the present invention, the ratio of the concentration of the oxidant in the first mixed solution to the concentration of the conductive polymer monomer in the second mixed solution is 1 to 1.2:1. A suitable ratio helps to reduce the residue of unreacted monomers or oxidants. If the concentration of the oxidant is too high, excessive oxidant will remain in the composite material, which will have a negative impact on the stability of the composite material, such as causing aging or degradation of the material; while if the concentration of the oxidant is too low, a large amount of unreacted conductive polymer monomers will remain, and these residual monomers will migrate or react during subsequent use, affecting the performance and stability of the composite material.

[0037] According to an embodiment of the present invention, the solvents used in the first mixed solution and the second mixed solution are each independently selected from N,N-dimethylformamide, dimethyl sulfoxide amide, alcohol solvents, or any one of the mixtures of N,N-dimethylformamide, dimethyl sulfoxide amide, alcohol solvents and water. Among them, the alcohol solvents include ethanol, isopropanol, etc. Good solubility and dispersibility enable metal ions, conductive polymer monomers and two-dimensional nanosheets to be fully mixed and evenly distributed in the solution. During subsequent reaction and curing processes, a more uniform composite material structure can be formed, reducing defects and non-uniformities inside the composite material, and improving the overall performance and stability of the composite material.

[0038] According to an embodiment of the present invention, the temperature of the oxidative polymerization reaction is -5 to 5 °C, and the time of the oxidative polymerization reaction is 0.5 to 1 h. A lower reaction temperature can effectively reduce the reaction rate, making the oxidative polymerization reaction more stable and controllable. The drying temperature is 30 to 40 °C, and the drying time is 2 to 4 h. The relatively low drying temperature can avoid the destruction of the composite material structure caused by high temperature (greater than 40 °C).

[0039] According to an embodiment of the present invention, the substrate is selected from any one of non-woven fabric, filter membrane, filter paper, hydrogel, glass plate, silicon wafer, mica sheet. When the substrate is selected from a glass plate, a silicon wafer, or a mica sheet, the substrate is subjected to a hydrophilic liquefaction treatment to obtain a hydrophilic surface. The hydrophilic liquefaction treatment is to change the material surface by physical or chemical methods to make it more easily contact with liquids, including: plasma treatment: introducing hydrophilic groups on the material surface using plasma; chemical coating: coating hydrophilic chemical substances such as polyvinyl alcohol (PVA); surface grafting: grafting hydrophilic groups on the surface through chemical reactions; ultraviolet light treatment: introducing hydrophilic groups on the surface using ultraviolet light; acid treatment: generating hydrophilic groups on the surface through acid etching.

[0040] As a second aspect of the present invention, an anisotropic conductive nanocomposite material is provided, which is prepared by using the above method.

[0041] In the embodiments of the present invention, anisotropic conductive nanocomposites with different conductive properties in different directions are prepared by using the above method. Through the oxidative polymerization reaction of conductive polymer monomers and oxidants in a nano-confined space, the growth and distribution of conductive polymer monomers can be precisely controlled, so that the conductive properties of the composite material can be regulated according to the design in different directions, realizing more precise anisotropic conductive properties and meeting the strict requirements of high-end electronic devices for conductive properties in specific directions and specific intensities. The nano-confined space is conducive to the formation of regular conductive channels by conductive polymer monomers, reducing electron scattering, thereby reducing the resistance of the composite material and improving its conductivity in a specific direction.

[0042] In the embodiments of the present invention, the thickness of the anisotropic conductive nanocomposite is 1-40 μm to meet diverse application requirements and broaden the application scope of the anisotropic conductive nanocomposite.

[0043] As the third aspect of the present invention, an application of the anisotropic conductive nanocomposite in an electronic device is provided.

[0044] In the embodiments of the present invention, the anisotropic conductive nanocomposite provided by the present invention has excellent conductivity in the horizontal direction and is much greater than the conductivity in the vertical direction, and has broad application prospects in the fields of electrical connection, wearable electronic devices, sensors, etc.

[0045] The present invention will be further described below through examples and related test experiments. In the following detailed description, for the sake of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present invention. However, obviously, one or more embodiments can also be implemented without these specific details. Moreover, without conflict, the details in the following embodiments can be arbitrarily combined into other feasible embodiments. All instruments, consumables, reagents, etc. in the following examples can be obtained from commercial channels without special instructions.

[0046] Examples 1-3

[0047] In Examples 1-3 of the present embodiment, anisotropic conductive nanocomposites were prepared according to the raw material ratios shown in Table 1. The raw materials used in Examples 1-3 of the present embodiment include pyrrole, montmorillonite (MMT) nanosheets, and FeCl 3 . Among them, FeCl 3 provides both Fe ions and acts as an oxidant. The pyrrole monomer was purchased from Aladdin, CAS number: 109-97-7; the MMT nanosheets were purchased from nanocor, model PGW; FeCl 3 was purchased from Macklin, CAS number: 7705-08-0.

[0048] Figure 2This is the preparation flow chart of the anisotropic conductive nanocomposite material in Embodiment 1 of the present invention, as shown in Figure 2 shown, and the specific preparation method is as follows.

[0049] (1) Prepare a 0.2M FeCl 2 solution using a dimethylformamide (DMF) / H 3 O mixed solvent with a volume ratio of 1:1. Provide a nylon filter membrane with a lyophilic surface (the amide groups on the surface of the nylon filter membrane make it hydrophilic, and the hydrophilicity of the nylon filter membrane can be enhanced by plasma treatment), and drop the above-mentioned 0.2M FeCl 3 solution to form a liquid film 1 on the surface of the nylon filter membrane. Disperse MMT nanosheets with a mass fraction of 2wt% using a DMF / H 2 O solvent with a volume ratio of 1:1. Mix pyrrole with 10 ml of a 2wt% MMT nanosheet dispersion evenly by shaking and ultrasonic treatment (5 - 10 min). Pour the above-mentioned pyrrole and MMT nanosheet mixture onto the liquid film 1 on the nylon filter membrane substrate in an environment of 0°C.

[0050] (2) The MMT nanosheets (two-dimensional nanosheets 5) undergo super-spreading and are cross-linked and cured by Fe ions (metal ions 3), forming a nano-confined space between two adjacent MMT nanosheets parallel to the substrate. Inside the nano-confined space, pyrrole (conductive polymer monomer 4) undergoes an oxidation polymerization reaction with FeCl 3 (oxidant 4). After reacting for 0.5 h, a composite film is obtained.

[0051] (3) Dry the composite film at 40°C for 2 h to obtain the anisotropic conductive nanocomposite material.

[0052] Table 1 Raw material ratios of Examples 1 - 3

[0053]

[0054] Example 4

[0055] In this Example 4, an anisotropic conductive nanocomposite material was prepared, and the raw materials used included pyrrole, MMT nanosheets, CaCl 2 , and ammonium persulfate. Among them, pyrrole monomer (CAS No.: 109 - 97 - 7), CaCl 2 (CAS No.: 10043 - 52 - 4), and ammonium persulfate (CAS No.: 7727 - 54 - 0) were all purchased from Aladdin; the MMT nanosheets were purchased from nanocor, model PGW. The specific preparation method is as follows.

[0056] (1) Prepare a 0.2M CaCl 2 solution using a DMF / H2 and a 0.2 M ammonium persulfate mixed solution. Provide a nylon filter membrane with a lyophilic surface, and drop the above mixed solution to form a liquid film on the surface of the nylon filter membrane. Use a DMF / H 2 O solvent with a volume ratio of 1:1 to disperse MMT nanosheets with a mass fraction of 2 wt%. Mix 1.2 g of pyrrole with 10 ml of a 2 wt% MMT nanosheet dispersion by shaking and ultrasonic treatment. Pour the above mixed solution of pyrrole and MMT nanosheets onto the liquid film surface of the nylon filter membrane substrate at 0 °C.

[0057] (2) The MMT nanosheets undergo super-spreading and are crosslinked and cured by Ca ions to form a nano-confined space between two adjacent upper and lower MMT nanosheets parallel to the substrate. In the nano-confined space, pyrrole and ammonium persulfate undergo an oxidative polymerization reaction, and a composite membrane is obtained after reacting for 0.5 h.

[0058] (3) Dry the composite membrane at 40 °C for 2 h to obtain an anisotropic conductive nanocomposite.

[0059] Example 5

[0060] In this Example 5, an anisotropic conductive nanocomposite was prepared, and the raw materials used included pyrrole, graphene oxide (GO) nanosheets, and FeCl 3 . Among them, the pyrrole monomer was purchased from Aladdin, CAS No.: 109-97-7; the GO nanosheets were purchased from Gaoxi Co., Ltd., model GO-1; FeCl 3 was purchased from Macklin, CAS No.: 7705-08-0. The specific preparation method is as follows.

[0061] (1) Prepare a 0.2 M FeCl 2 solution using a DMF / H 3 O mixed solvent with a volume ratio of 1:1. Provide a nylon filter membrane with a lyophilic surface, and drop the above 0.2 M FeCl 3 solution to form a liquid film on the surface of the nylon filter membrane. Use a DMF / H 2 O solvent with a volume ratio of 1:1 to disperse GO nanosheets with a concentration of 2 mg / ml. Mix 1.2 g of pyrrole with 10 ml of a 2 mg / ml GO nanosheet dispersion by shaking and ultrasonic treatment. Pour the above mixed solution of pyrrole and GO nanosheets onto the liquid film surface of the nylon filter membrane substrate at 0 °C.

[0062] (2) The GO nanosheets undergo super-spreading and are crosslinked and cured by Fe ions to form a nano-confined space between two adjacent upper and lower GO nanosheets parallel to the substrate. In the nano-confined space, pyrrole and FeCl 3 undergo an oxidative polymerization reaction, and a composite membrane is obtained after reacting for 0.5 h.

[0063] (3) The composite film was dried at 40 °C for 2 h to obtain an anisotropic conductive nanocomposite material.

[0064] Example 6

[0065] In this Example 6, an anisotropic conductive nanocomposite material was prepared, and the raw materials used included aniline, MMT nanosheets and FeCl 3 . Among them, aniline monomer was purchased from Aladdin, CAS No.: 62-53-3; GO nanosheets were purchased from Gaoxi Co., Ltd., model GO-1; FeCl 3 was purchased from Macklin, CAS No.: 7705-08-0. The specific preparation method is as follows.

[0066] (1) A 0.2 M FeCl 2 solution was prepared using a DMF / H 3 O mixed solvent with a volume ratio of 1:1. A nylon filter membrane with a lyophilic surface was provided, and the above 0.2 M FeCl 3 solution was dropped to form a liquid film on the surface of the nylon filter membrane. A 2 wt% MMT nanosheet was dispersed using a DMF / H 2 O solvent with a volume ratio of 1:1. 1.2 g of aniline was mixed evenly with 10 ml of a 2 wt% MMT nanosheet dispersion by shaking and ultrasonic treatment. The above mixture of aniline and MMT nanosheets was poured onto the liquid film surface of the nylon filter membrane substrate in a 0 °C environment.

[0067] (2) The MMT nanosheets underwent super-spreading and were crosslinked and cured by Fe ions, forming a nano-confined space between two adjacent upper and lower MMT nanosheets parallel to the substrate. In the nano-confined space, aniline and FeCl 3 underwent an oxidative polymerization reaction, and a composite film was obtained after 0.5 h of reaction.

[0068] (3) The composite film was dried at 40 °C for 2 h to obtain an anisotropic conductive nanocomposite material.

[0069] Comparative Example 1

[0070] In this Comparative Example 1, a conductive nanocomposite material was prepared, and the raw materials used included pyrrole, MMT nanosheets and ammonium persulfate. Among them, pyrrole monomer (CAS No.: 109-97-7) and ammonium persulfate (CAS No.: 7727-54-0) were both purchased from Aladdin; MMT nanosheets were purchased from nanocor, model PGW. The specific preparation method is as follows.

[0071] (1) A 2 wt% MMT nanosheet was dispersed using a DMF / H 2 O solvent with a volume ratio of 1:1.

[0072] (2) 1.2 g of pyrrole and 0.2 M of ammonium persulfate were mixed uniformly with 10 ml of a 2 wt% MMT nanosheet dispersion by shaking and ultrasonication.

[0073] (3) The above mixture of pyrrole, ammonium persulfate, and MMT nanosheets was cast into a mold and reacted in an environment of 0 °C for 0.5 h to obtain a composite film.

[0074] (4) The composite film was dried at 40 °C for 2 h to obtain a conductive nanocomposite.

[0075] The difference between Comparative Example 1 and Example 4 is that a traditional casting method (casting) was used, that is, the reaction solution was directly poured into a mold of 10 cm × 10 cm, and finally dried at 40 °C to prepare the MMT / PPy conductive nanocomposite.

[0076] Further, the composites obtained in the above examples and comparative examples were subjected to structural characterization and performance testing.

[0077] The structure of the anisotropic conductive nanocomposite in Example 1 was characterized by scanning electron microscopy (SEM). Specifically, the anisotropic conductive composite was cooled with liquid nitrogen for 0.5 - 1 h, the cross-section obtained by impact fracture was used, and the cross-sectional morphology was observed by scanning electron microscopy at an accelerating voltage of 20 KV. Figure 3 This is the scanning electron micrograph of the anisotropic conductive nanocomposite in Example 1 of the present invention at a magnification of 5000×; Figure 4 This is the scanning electron micrograph of the anisotropic conductive nanocomposite in Example 1 of the present invention at a magnification of 10000×.

[0078] From Figure 3 and Figure 4 It can be seen that the composite material exhibits an obvious layered structure, and there are certain gaps and boundaries between the layers. This verifies the super-spreading of two-dimensional nanosheets during the preparation process and the polymerization of conductive polymer monomers in the nano-confined space. That is, through super-spreading, the MMT nanosheets are oriented and arranged to form an ordered multi-layer structure, and polypyrrole polymerizes and grows between the MMT layers.

[0079] In order to further prove that pyrrole polymerizes in the nano-confined space formed by MMT nanosheets, transmission electron microscopy (TEM) and X-ray diffraction (XRD) were used to test the change in the layer spacing of MMT nanosheets. Figure 5 This is the transmission electron micrograph of the anisotropic conductive nanocomposite in Example 1 of the present invention; Figure 6 This is the X-ray diffraction pattern of the anisotropic conductive nanocomposite in Example 1 of the present invention.

[0080] As Figure 5As shown, an ordered arrangement of MMT nanosheets can be seen, and a layered PPy crystallization region is formed between the neatly arranged nanosheets. As Figure 6 shown, due to the incorporation of PPy, the diffraction peak of the anisotropic conductive nanocomposite in Example 1 shifted from 6.1° to 4.6°, indicating that PPy was successfully synthesized between the MMT nanosheet layers. Consistent with Figure 5 the TEM results of

[0081] Figure 7 This is the X-ray diffraction pattern of the anisotropic conductive nanocomposite in Example 5 of the present invention.

[0082] As Figure 7 shown, it can be found that the diffraction peak of the anisotropic conductive nanocomposite in Example 5 shifted from 10.8° to 9.3°, and the layer spacing increased, indicating that PPy was successfully synthesized between the GO nanosheet layers.

[0083] Figure 8 This is a schematic diagram of the conductivity test in the horizontal direction in the embodiments of the present invention. The specific test method is: the four-electrode (four-probe) method. Electrodes are made at both ends of the sample through silver paste. The conductivity in the horizontal direction is calculated by formulas (1)-(3).

[0084] (1);

[0085] (2);

[0086] (3).

[0087] Among them, S is the cross-sectional area of the test sample, H is the width of the test sample, D is the thickness of the test sample, R is the test resistance, L is the distance between the positive and negative electrodes, ρ is the resistivity of the test sample, and σ is the conductivity of the test sample.

[0088] Figure 9 This is a schematic diagram of the conductivity test in the vertical direction in the embodiments of the present invention. The specific test method is: the four-electrode (four-probe) method. The electrode material is copper foil. The conductivity in the vertical direction is calculated by formulas (4)-(6).

[0089] (4);

[0090] (5);

[0091] (6).

[0092] Among them, S is the area of the test sample, Pi is π, r is the radius of the test sample, R is the test resistance, L is the distance between the positive and negative electrodes, ρ is the resistivity of the test sample, and σ is the conductivity of the test sample.

[0093] Through Figure 8 and Figure 9 The conductivity of the anisotropic conductive nanocomposite in different directions in the above-mentioned examples and comparative examples was tested by the method shown, and the test results are shown in Table 2.

[0094] Table 2 Conductivity of anisotropic conductive nanocomposites in different directions in Examples 1-6 and Comparative Example 1

[0095]

[0096] It can be found from Table 2 that the overall horizontal conductivity and vertical conductivity of the examples are much higher than those of Comparative Example 1. Taking the horizontal conductivity as an example, the horizontal conductivity of Examples 1-3 ranges from 2.37 to 3.93 S / cm. Although the horizontal conductivity of Examples 4-6 decreases, it is still in the order of 10 -6 -10 -7 S / cm, while the horizontal conductivity of Comparative Example 1 is only 1.8499×10 -9S / cm, which indicates that the composite materials in the examples are significantly superior to those in Comparative Example 1 in terms of electrical conductivity. For Examples 1-3, the horizontal electrical conductivity is much higher than the vertical electrical conductivity, with a difference of 3-5 orders of magnitude between the two, showing obvious anisotropic electrical conductivity characteristics of the materials. Examples 4-6 also exhibit this anisotropy. Although the absolute values of their horizontal and vertical electrical conductivities are relatively low, the horizontal electrical conductivity is still higher than the vertical electrical conductivity. This is because, under the action of the shear fluid flow, the two-dimensional nanosheets are oriented and arranged in the direction parallel to the liquid film, and at the same time are crosslinked and cured by metal ions. In the direction perpendicular to the liquid film, a nano-confined space is formed between adjacent two-dimensional nanosheets, and the conductive polymer monomer and the oxidant undergo an oxidative polymerization reaction in the nano-confined space, thus obtaining an anisotropic conductive nanocomposite material. Specifically, in the direction parallel to the liquid film, the oxidative polymerization reaction of the conductive polymer material occurs between the upper and lower two-dimensional nanosheets, making the conductive nanocomposite material have good electrical conductivity in the direction parallel to the liquid film; at the same time, due to the poor electrical conductivity of the two-dimensional nanosheets used, the upper and lower two-dimensional nanosheets cause hindrance, resulting in poor electrical conductivity of the conductive nanocomposite material in the direction perpendicular to the liquid film. In the comparative example, the MMT nanosheet layers are randomly stacked to form a disordered structure. The PPy molecules are randomly distributed between or on the surface of the MMT nanosheet layers, resulting in discontinuous conductive paths in both the horizontal and vertical directions. The electron transport needs to cross more interfaces or insulating MMT nanosheet layers, resulting in lower electrical conductivity, especially in the vertical direction. Moreover, the structure of ordinary casting is relatively loose, with more interface defects and pores, which hinders the continuity of the conductive path. However, due to the super-spreading on the liquid film surface, the interlayer distance of the two-dimensional nanosheets is more uniform, so that the conductive path of the conductive nanocomposite material in the vertical direction in the examples is better than that in Comparative Example 1.

[0097] The specific embodiments described above further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing an anisotropic conductive nanocomposite material, characterized in that: include: applying a first mixed solution containing metal ions and an oxidant on a substrate having a lyophilic surface to form a liquid film on the lyophilic surface; Pour a second mixed liquid formed by uniformly mixing a conductive polymer monomer and a two-dimensional nanosheet dispersion liquid onto the surface of the liquid film and allow to stand for a period of time, wherein the two-dimensional nanosheets are super-spread on the surface of the liquid film and oriented in a first direction, then the metal ions are cross-linked and cured with the two-dimensional nanosheets, and a nano-confined space is formed between adjacent two-dimensional nanosheets in a second direction, wherein the first direction is parallel to the substrate, and the second direction is perpendicular to the substrate, and within the nano-confined space, the conductive polymer monomer and the oxidant undergo an oxidative polymerization reaction to obtain a composite film; The composite film is dried to obtain an anisotropic conductive nanocomposite material.

2. The method according to claim 1, characterized in that The metal ion is selected from at least one of iron ion, calcium ion and aluminum ion; The oxidant is selected from at least one of hydrogen peroxide, dichromate, persulfate, and ferric chloride; The concentration of metal ions in the first mixed solution is 0.2-3 mol / L.

3. The method according to claim 1, characterized in that The conductive polymer monomer is selected from at least one of aniline, pyrrole, and 3,4-ethylenedioxythiophene; The two-dimensional nanosheet is selected from at least one of montmorillonite nanosheet, graphene oxide nanosheet, and MXene nanosheet; The concentration of the two-dimensional nanosheets in the second mixed solution is 1-40 mg / mL.

4. The method according to claim 3, characterized in that The mass ratio of the conductive polymer monomer to the two-dimensional nanosheet is 1-100:1; The ratio of the concentration of the oxidant in the first mixed solution to the concentration of the conductive polymer monomer in the second mixed solution is 1-1.2:

1.

5. The method according to claim 1, characterized in that The solvents used in the first mixed solution and the second mixed solution are independently selected from any one of N,N-dimethylformamide, dimethylsulfinamide, alcohol solvents, a mixture of N,N-dimethylformamide and water, a mixture of dimethylsulfinamide and water, and a mixture of alcohol solvents and water.

6. The method according to claim 1, characterized in that The temperature of the oxidative polymerization reaction is -5 to 5°C, and the time of the oxidative polymerization reaction is 0.5 to 1 hour.

7. The method according to claim 1, characterized in that The substrate is selected from any one of non-woven fabrics, filter membranes, filter paper, hydrogels, glass plates, silicon wafers, and mica sheets; When the substrate is selected from a glass plate, a silicon wafer, or a mica sheet, the substrate is subjected to a lyophilic treatment to obtain a lyophilic surface.

8. An anisotropic conductive nanocomposite material, characterized in that: The method is prepared according to any one of claims 1 to 7.

9. Use of the anisotropic conductive nanocomposite material as claimed in claim 8 in electronic devices.

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