CN108203543B - Graphene-reinforced polyimide nanocomposite material and preparation method and application thereof - Google Patents

Abstract

The invention discloses a graphene-reinforced polyimide nanocomposite material and a preparation method and application thereof. The graphene-enhanced polyimide nanocomposite material is mainly composed of two-dimensional graphene nanosheets, polyimide, and polyaniline nanofibers and/or polyaniline nanoparticles. The graphene-reinforced polyimide nanocomposite material of the present invention has excellent mechanical properties, high temperature resistance and wear resistance, especially low friction coefficient and wear rate, and can be used in aerospace, construction, chemical industry, petroleum, In the fields of long-term erosion resistance, wear resistance and anti-corrosion of particles, coal powder, dust, flue gas and liquid in electric power, metallurgy, shipbuilding, light textile, storage, transportation, aerospace and other industries, the preparation process is simple and the source of raw materials is wide, which is conducive to the scale implementation.

Description

Graphene-reinforced polyimide nanocomposite material and its preparation method and application

technical field

The invention specifically relates to a graphene-reinforced polyimide nanocomposite material, a preparation method and application thereof, and belongs to the field of polymer nanocomposite materials.

Background technique

Polyimide (PI) has excellent mechanical properties, excellent thermal stability and low dielectric constant, and has been widely used in microelectronics, aerospace engineering, adhesives, fuel cells and other fields. However, polyimide itself also has some shortcomings, which limits its application. For example, in the aerospace field, the radiation of high-energy particles will cause the polyimide to accumulate charges, form a current tree, and the atomic oxygen energy is high, which will cause "erosion" to the PI body, reduce the mechanical properties of the material, and cause the material to fail. At the same time, the environment in the aerospace field is harsh, and the temperature resistance of materials is also very high, but the temperature resistance of polyimide cannot meet such requirements; in addition, polyimide has a high friction coefficient, which limits its use in Applications in the field of insulation and heat conduction.

At present, there are many researches on polyimide composites, but there are few researches on friction and wear properties. Nowadays, the research on tribological modification of polyimide is gradually increasing. It is no longer the same as in the past with single means and limited improvement effect. The mainstream research mainly starts from structural modification and composite modification. For example, from the perspective of segment design , Prepolymers with different molecular weights were prepared by introducing phenylacetylene end-capping agent in the precursor polycondensation reaction, and then the end-capping modified polyimide matrix material was prepared through addition reaction; secondly, from the perspective of interface design, different molecular weights were prepared The fillers (such as graphene, boron nitride, etc.) or fillers with different surface modifications, or chemical composites such as graphene oxide/nano-polytetrafluoroethylene composite fillers, are prepared by in-situ polymerization or direct blending. Imide composites. The former has a complex reaction, high cost and poor effect; the latter mainly focuses on the surface covalent bond modification of graphene, but this technology will destroy the structure of graphene and affect the improvement of the performance of composite materials to a certain extent.

SUMMARY OF THE INVENTION

The main purpose of the present invention is to provide a graphene-reinforced polyimide nanocomposite material and its preparation method and application to overcome the deficiencies in the prior art.

In order to realize the foregoing invention purpose, the technical scheme adopted in the present invention includes:

The present invention provides a graphene-reinforced polyimide nanocomposite material, which comprises graphene two-dimensional nanosheets, polyimide, and polyaniline nanofibers and/or polyaniline nanoparticles.

Further, the graphene-reinforced polyimide nanocomposite material is formed by a composite of graphene two-dimensional nanosheets, polyimide and polyaniline nanofibers or nanoparticles.

The present invention also provides a method for preparing a graphene-reinforced polyimide nanocomposite material, comprising:

Mixing two-dimensional graphene nanosheets with polyaniline nanofibers and/or polyaniline nanoparticles in a solvent to obtain a dispersion of two-dimensional graphene nanosheets;

Mixing the dispersion of the graphene two-dimensional nanosheet with aromatic diamine and aromatic dianhydride, and in situ polymerization of the aromatic diamine and aromatic dianhydride to form a polyamide prepolymer/graphene composite, Then, the polyamide prepolymer is subjected to an imidization reaction to obtain the graphene-reinforced polyimide nanocomposite.

In some embodiments, the graphene-enhanced polyimide nanocomposite can be obtained by imidizing the polyamide prepolymer in the polyamide prepolymer/graphene composite by gradient heating.

In some embodiments, the preparation method includes: mixing graphene powder and/or two-dimensional graphene nanosheets with polyaniline nanofibers and/or polyaniline nanoparticles in a solvent to obtain two-dimensional graphene nanosheets tablet dispersion. .

Further, the aforementioned polyimide includes a polycondensation-type aromatic polyimide, which can be preferably formed by in-situ polymerization of an aromatic diamine and an aromatic dianhydride, for example.

The present invention also provides the application of the graphene-reinforced polyimide nanocomposite material, for example, the use of the graphene-reinforced polyimide nanocomposite material in preparing a protective structure with at least anti-corrosion and wear-resistant properties.

Compared with the prior art, the graphene-reinforced polyimide nanocomposite material of the present invention has excellent mechanical properties, high temperature resistance and wear resistance, especially low friction coefficient and wear rate, and can be applied in aerospace, construction, etc. , chemical, petroleum, electric power, metallurgy, shipbuilding, textile, storage, transportation, aerospace and other industries in the field of long-term erosion resistance, wear resistance and corrosion resistance of particles, coal powder, dust, flue gas and liquid, and its preparation process is simple, raw materials Wide range of sources, conducive to large-scale implementation.

Description of drawings

Fig. 1 is the mechanical property test chart of the graphene-reinforced polyimide nanocomposite obtained in Example 1-4 and the polyimide material obtained in Comparative Example 1;

Fig. 2 is the thermal stability test chart of the graphene-reinforced polyimide nanocomposite material obtained in Example 1-4 and the polyimide material obtained in Comparative Example 1;

Fig. 3 is the Vickers hardness test pattern of the graphene-reinforced polyimide nanocomposite material obtained in Example 1-4 and the polyimide material obtained in Comparative Example 1;

4 is an analysis diagram of the wear resistance of the graphene-reinforced polyimide nanocomposite material obtained in Examples 1-4 and the polyimide material graphene-reinforced polyimide nanocomposite material obtained in Comparative Example 1;

5 is an SEM analysis diagram of the wear scars of the graphene-reinforced polyimide nanocomposite materials obtained in Examples 1-4 and the polyimide material obtained in Comparative Example 1.

Detailed ways

In order to make the technical solutions of the present invention clearer and easier to understand, the present invention will be specifically described below with reference to the accompanying drawings and examples. However, it should be understood that the examples described herein are only used to illustrate and explain the present invention, and not to limit the present invention.

An aspect of the embodiments of the present invention provides a graphene-reinforced polyimide nanocomposite material including graphene two-dimensional nanosheets, polyimide, and polyaniline nanofibers and/or polyaniline nanoparticles.

In some embodiments, the graphene-reinforced polyimide nanocomposite is formed by a composite of graphene two-dimensional nanosheets, polyimide, and polyaniline nanofibers and/or polyaniline nanoparticles.

Further, in the graphene-reinforced polyimide nanocomposite material, at least part of polyaniline nanofibers and/or polyaniline nanoparticles and graphene two-dimensional nanosheets are physically combined to form a composite.

In some embodiments, the content of graphene two-dimensional nanosheets in the graphene-reinforced polyimide nanocomposite is 0.1wt% to 50wt%, preferably 0.25wt% to 10wt%, particularly preferably 0.25wt% ~1 wt%.

In some embodiments, the graphene-reinforced polyimide nanocomposite includes 0.1wt%-50wt% graphene two-dimensional nanosheets, 19.23wt%-76.81wt% polyimide, 0.05wt%-25wt% Polyaniline nanofibers and/or polyaniline nanoparticles.

In some preferred embodiments, the graphene-reinforced polyimide nanocomposite comprises 0.25wt%-1wt% graphene two-dimensional nanosheets, 65.38wt%-76.35wt% polyimide and 0.25wt%- 1 wt% polyaniline nanofibers and/or polyaniline nanoparticles.

In some preferred embodiments, the mass ratio of the graphene two-dimensional nanosheets, polyaniline nanofibers and/or polyaniline nanoparticles to polyimide is 0.15:76.81 to 15:65.38, particularly preferably 0.25: 76.35-1:71.15.

Further, the diameter of the polyaniline nanofibers is preferably 10-300 nm, particularly preferably 10-100 nm.

Further, the length of the polyaniline nanofibers is preferably 0.5-5 μm, particularly preferably 0.5-2 μm.

Further, the particle size of the polyaniline nanoparticles is 50-500 nm, preferably 100-200 nm.

Further, the material of the aforementioned polyaniline nanofibers or polyaniline nanoparticles can be selected from polyaniline or alkyl-substituted polyaniline, etc., such as poly-o-methylaniline, poly-o-ethylaniline, poly-o-propylaniline, poly-o- Phenylenediamine, polybutylaniline, etc., are not limited thereto. These polyanilines or alkyl-substituted polyanilines may all be eigenstates.

Further, the aforementioned polyimide includes polycondensation type aromatic polyimide. Preferably, the polyimide is formed by in-situ polymerization of an aromatic diamine and an aromatic dianhydride. The aforementioned aromatic diamine includes diamines having an aromatic structure such as 4,4 diaminodiphenyl ether, 4,4 diaminobiphenyl, and 3,4 diaminodiphenyl ether, and is not limited thereto. The aforementioned aromatic dianhydride includes pyromellitic anhydride, benzophenone dianhydride, biphthalic anhydride, trimellitic anhydride and other acid anhydrides containing an aromatic structure, and is not limited thereto.

Another aspect of the embodiments of the present invention provides a method for preparing a graphene-reinforced polyimide nanocomposite material, comprising:

Mixing two-dimensional graphene nanosheets with polyaniline nanofibers and/or polyaniline nanoparticles in a solvent to obtain a dispersion of two-dimensional graphene nanosheets;

Mixing the dispersion of the graphene two-dimensional nanosheet with aromatic diamine and aromatic dianhydride, and in situ polymerization of the aromatic diamine and aromatic dianhydride to form a polyamide prepolymer/graphene composite, Then, the polyamide prepolymer is subjected to an imidization reaction to obtain the graphene-reinforced polyimide nanocomposite.

In some embodiments, the preparation method includes: mixing graphene powder and/or two-dimensional graphene nanosheets with polyaniline nanofibers and/or polyaniline nanoparticles in a solvent to obtain two-dimensional graphene nanosheets tablet dispersion.

Further, in some specific embodiments, the preparation method may also include: mixing two-dimensional graphene nanosheets with polyaniline nanofibers and/or polyaniline nanoparticles in a solvent, and performing ultrasonic treatment, A dispersion of graphene two-dimensional nanosheets was obtained.

Further, in some specific embodiments, the preparation method may also include: stirring, ultrasonic, vibration and other physical means (for example, mechanical stirring, ultrasonic (of course in some embodiments, other suitable non- physical method) simply physically mixing graphene powder with polyaniline nanofibers and/or polyaniline nanoparticles in a solvent to obtain a dispersion of two-dimensional graphene nanosheets. Of course, in these embodiments, if graphene If the powder is excessive, the graphene particles in the form of sediments and the like need to be removed by liquid separation, centrifugation, etc., so as to obtain a uniform graphene two-dimensional nanosheet dispersion.

For example, in one embodiment, butyl polyaniline nanofibers can be dissolved in DMAC, graphene powder can be added, and the two-dimensional graphene nanosheets can be exfoliated by ultrasonication for about 1 h, which are uniformly dispersed in DMAC to form Homogeneous dispersion of two-dimensional graphene nanosheets.

In some embodiments, the graphene-enhanced polyimide nanocomposite can be obtained by imidizing the polyamide prepolymer in the polyamide prepolymer/graphene composite by gradient heating.

Further, in some specific embodiments, the preparation method includes: heating the polyamide prepolymer/graphene composite at 100°C～150°C for 1h～4h, and then heating at 200°C～300°C Heating for 1 h to 4 h to obtain the graphene-reinforced polyimide nanocomposite material.

Further, in some more specific embodiments, the preparation method may include: heating the polyamide prepolymer/graphene composite at a constant temperature of 100°C to 120°C and 150°C to 170°C, respectively. 1h to 3h, and then successively heated at 200°C to 220°C, 250°C to 270°C, and 300°C to 320°C for 1h to 2h, respectively, to obtain the graphene-reinforced polyimide nanocomposite material.

Further, in the aforementioned embodiment, the mass ratio of the graphene powder to the polyaniline nanofibers and/or polyaniline nanoparticles is preferably 1:10-1:0.1, particularly preferably 1:1-3:1 .

Further, in the aforementioned embodiments, the mass ratio of the graphene two-dimensional nanosheets to the polyaniline nanofibers and/or polyaniline nanoparticles is preferably 1:5 to 2:1, particularly preferably 1:1 to 2 :1.

Further, the polyaniline nanofibers or nanoparticles, aromatic diamines, aromatic dianhydrides, etc. can be as described above, and will not be repeated here.

Further, the aforementioned solvent may be selected from organic solvents, particularly preferably high-boiling polar organic solvents, for example, may be preferably selected from any one or more of DMAC, DMF, NMP, etc., and is not limited thereto.

In the aforementioned embodiments of the present invention, by virtue of the weak physical interaction between polyaniline nanofibers or/or polyaniline rice particles and graphene two-dimensional nanosheets, graphene two-dimensional nanosheets can be transformed from graphene powders The obtained graphene two-dimensional nanosheets have good physical/chemical structure and morphology, and the graphene two-dimensional nanosheets are well dispersed in organic solvents and other dispersion media to obtain uniform and stable graphite. Two-dimensional nanosheet dispersions. Further, the graphene reinforced polyimide nanocomposite can be prepared by using the graphene two-dimensional nanosheet dispersion liquid to cooperate with polyimide precursors (aromatic diamines, aromatic dianhydrides, etc.), etc. material, and in the graphene-reinforced polyimide nanocomposite material, the graphene two-dimensional nanosheets are in a uniformly dispersed state, which can not only effectively prevent charge accumulation in the polyimide composite material, but also greatly improve the The mechanical properties and anti-radiation properties of imide composite materials can also significantly improve the thermal properties (especially high temperature resistance) and friction resistance of polyimide composite materials, so that they can also be used in wear-resistant and self-lubricating materials. The field has a wide range of application prospects.

The embodiment of the present invention also provides a graphene-reinforced polyimide nanocomposite material prepared by any of the foregoing methods.

The present invention also provides the use of the graphene-reinforced polyimide nanocomposite material, for example, the use in the preparation of a protective structure with at least anti-corrosion and wear-resistant properties.

For example, the uncured polyamide prepolymer graphene nanocomposite can be applied to the surface of the substrate by casting, spraying, spin coating, printing, blade coating, etc., followed by thermal curing or photocuring, Forms a protective coating.

For example, the graphene-reinforced polyimide nanocomposite in the form of sheet, block, etc. can also be used as a protective material.

The technical solutions of the present invention will be further described in detail below with reference to several embodiments. The polyaniline, poly-o-methylaniline, poly-o-propylaniline, poly-o-phenylenediamine, polybutylaniline, etc. used in the following examples can be prepared by methods known in the industry or purchased from commercial sources.

Embodiment 1 This embodiment relates to a graphene-reinforced polyimide nanocomposite material (the graphene content in the composite material is 0.25wt%, referred to as 0.25%G/PI), and its preparation method includes the following steps:

Synthesis of polybutylaniline nanofibers: the butylaniline monomer was dissolved in 1M hydrochloric acid, then an equimolar amount of ammonium persulfate was added to the above solution and left standing at room temperature for 24 hours, and the diameter was obtained after filtration and washing. Polyaniline nanofibers with a length of 50 nm and a length of 5 μm were added to dedope with hydrazine hydrate, washed three times with distilled water, and dried to obtain intrinsic polybutylaniline nanofibers (referred to as polyaniline nanofibers).

The aforementioned polyaniline nanofibers (0.01 g), two-dimensional graphene nanosheets (0.01 g) and solvent N,N dimethylacetamide (28 mL) were weighed and sonicated for one hour, and then 4, 4 Diaminodiphenyl ether (2.00g) and pyromellitic anhydride (2.18g) were mechanically stirred in a nitrogen atmosphere for 24h at room temperature to obtain a polyamide prepolymer graphene nanocomposite, and the polyamide prepolymer graphite The alkene nanocomposite was placed on a constant temperature heating table and heated at 100 °C and 150 °C for 1 h each to remove a large amount of solvent DMAC, and then placed in a muffle furnace for 1 h at 200 °C, 250 °C, and 300 °C, respectively. Complete imidization is achieved to obtain graphene-reinforced polyimide nanocomposite.

Embodiment 2 This embodiment relates to a graphene-reinforced polyimide nanocomposite material (the graphene content in the composite material is 0.5wt%, referred to as 0.5%G/PI), and its preparation process includes:

Weigh poly-o-toluidine nanofibers (0.02g, 50nm in diameter, 5μm in length), graphene two-dimensional nanosheets (0.02g) and solvent N,N dimethylformamide (28mL), mix and sonicate for one hour, 4,4 diaminodiphenyl ether (2.00g) and biphenyl dianhydride (2.18g) were added to the obtained mixed solution, and mechanically stirred in a nitrogen atmosphere for 24h at room temperature to obtain a polyamide prepolymer graphene nanocomposite , the polyamide prepolymer graphene nanocomposite was placed on a constant temperature heating table at 100 °C and 150 °C for 1 h at a constant temperature to remove a large amount of solvent DMAC, and then placed in a muffle furnace at 200 °C, 250 °C, 300 °C Heating at a constant temperature for 1 h at ℃ to achieve complete imidization and obtain graphene-reinforced polyimide nanocomposite.

Embodiment 3 This embodiment relates to a graphene-reinforced polyimide nanocomposite material (the graphene content in the composite material is 1wt%, referred to as 1%G/PI for short), and its preparation process includes:

Weighed poly-o-phenylenediamine nanofibers (0.04g, 80nm in diameter, 5μm in length), graphene two-dimensional nanosheets (0.04g) and solvent N,N dimethylacetamide (28mL) were mixed and sonicated for one hour, 4,4 diaminodiphenyl ether (2.00g) and trimellitic anhydride (2.18g) were added to the obtained mixed solution, and mechanically stirred in a nitrogen atmosphere for 24h at room temperature to obtain a polyamide prepolymer graphene nanocomposite. The amide prepolymer graphene nanocomposite was placed on a constant temperature heating table and heated at 100 °C and 150 °C for 1 h each to remove a large amount of solvent DMAC, and then placed in a muffle furnace at 200 °C, 250 °C, and 300 °C. Heating at a constant temperature for 1 h to achieve complete imidization to obtain a graphene-reinforced polyimide nanocomposite material.

Embodiment 4 This embodiment relates to a graphene-reinforced polyimide nanocomposite material (the graphene content in the composite material is 2wt%, referred to as 2%G/PI), and its preparation process includes:

Weigh poly-o-propylaniline nanofibers (0.08g, with a diameter of 60nm and a length of 2μm), graphene two-dimensional nanosheets (0.08g) and solvent methylpyrrolidone (28mL) and mixed with ultrasonic for one hour. 4,4 diaminodiphenyl ether (2.00g) and benzophenone dianhydride (2.18g) were added to the mixture, and mechanically stirred for 24h in a nitrogen atmosphere at room temperature to obtain a polyamide prepolymer graphene nanocomposite. The prepolymer graphene nanocomposite was placed on a constant temperature heating table and heated at 100 °C and 150 °C for 1 h each to remove a large amount of solvent DMAC, and then placed in a muffle furnace at 200 °C, 250 °C, and 300 °C for each constant temperature. After heating for 1 h, complete imidization was achieved, and a graphene-reinforced polyimide nanocomposite was obtained.

Embodiment 5 This embodiment relates to a graphene-reinforced polyimide nanocomposite material (the graphene content in the composite material is 1wt%, referred to as 1%G/PI), and its preparation process includes:

Weighing poly-o-phenylenediamine nanoparticles (0.08g, particle size of 200nm), graphene two-dimensional nanosheets (0.08g) and solvent N,N dimethylacetamide (28mL) were mixed and ultrasonicated for one hour. 4,4 diaminodiphenyl ether (2.00g) and benzophenone dianhydride (2.18g) were added to the mixed solution, and mechanically stirred in a nitrogen atmosphere for 24h at room temperature to obtain a polyamide prepolymer graphene nanocomposite. The polyamide prepolymer graphene nanocomposite was placed on a constant temperature heating table at 100 °C and 150 °C for 1 h each to remove a large amount of solvent DMAC, and then placed in a muffle furnace at 200 °C, 250 °C, and 300 °C. Heating at a constant temperature for 1 h, thereby achieving complete imidization, and obtaining a graphene-reinforced polyimide nanocomposite material.

Comparative Example 1 The preparation process of a pure polyimide material involved in this comparative example includes:

4,4 diaminodiphenyl ether (2.00g) and pyromellitic anhydride (2.18g) were placed in a solvent N,N dimethylacetamide (28mL) to obtain a mixed solution, and the mixture was prepared in a nitrogen atmosphere at room temperature. Stir for 24 hours to obtain a polyamide prepolymer, place the polyamide prepolymer on a constant temperature heating table for 1 hour at 100°C and 150°C for each constant temperature to remove a large amount of solvent DMAC, and then place it in a muffle furnace at 200°C , 250°C, and 300°C for 1 h at a constant temperature, so as to achieve complete imidization and obtain a polyimide material (pure PI).

Further, FIGS. 1 a to 1 c are graphs of mechanical property data of the graphene-reinforced polyimide nanocomposite materials obtained in Examples 1-4 and the polyimide material obtained in Comparative Example 1. It can be seen that the storage modulus of pure polyimide is about 1480MPa, while the graphene/polyimide composite films are all over 2100MPa, and the performance is improved by more than 42%; the change of loss modulus and storage modulus is similar, The enhanced performance may be attributed to the well-dispersed graphene/polyaniline nanofiber composites in the PI matrix, and the graphene sheets with high modulus and large aspect ratio can effectively prevent or inhibit the migration of polymer segments. , and transfer part of the external stress; the relationship between mechanical loss and temperature shows that the Tg is reduced after the addition of graphene/polyaniline nanofiber composites, the reason may be that the added AT affects the structure of PI, which makes the local existence of the composite film relatively weak. low interaction force.

2a-2b are data graphs of the thermal stability properties of the graphene-reinforced polyimide nanocomposites obtained in Examples 1-4 and the polyimide material obtained in Comparative Example 1. It can be seen that when the mass fraction is degraded to T _D10 and T _D50 , the thermal decomposition temperature of the graphene/polyimide composite film is higher than that of pure polyimide, indicating that the addition of graphene with good thermal stability After /polyaniline nanofiber composites, the thermal stability of the composites was improved.

Fig. 3 is the hardness value test result of the graphene-reinforced polyimide nanocomposite obtained in Examples 1-4 and the polyimide material obtained in Comparative Example 1. It can be seen that adding graphene/polyaniline nanofibers After compounding, the hardness of the material has been significantly improved.

4a-4b respectively show the analysis results of the wear resistance of the graphene-reinforced polyimide nanocomposites obtained in Examples 1-4 and the polyimide material obtained in Comparative Example 1. It can be seen that the incorporation of a certain amount of graphene/polyaniline nanofiber composite into the PI matrix can significantly reduce the average friction coefficient, among which the graphene/polyimide composite coating with a content of 1 wt% has the most obvious improvement, and the average friction The coefficient is reduced by 37%. And with the increase of graphene content, the wear rate of the composite coating is basically the same as the average friction coefficient. When the content is 0.25wt%, the wear rate is reduced by 76%; It improves the thermal conductivity of the coating, effectively relieves the heat generated during the friction process, and maintains its own excellent mechanical properties.

5a-5e show the SEM analysis diagrams of the wear scars of the graphene-reinforced polyimide nanocomposites obtained in Examples 1-4 and the polyimide material obtained in Comparative Example 1, respectively. It can be seen that the rigidity of pure polyimide is relatively small and the wear scar width is large; the incorporation of a certain amount of graphene/polyaniline nanofiber composites effectively reduces the wear scar width, and the wear scar morphology reflects the The reason for the extrusion deformation is that a transfer film is formed after the addition of graphene, and plastic deformation occurs, which is beneficial to improve the wear resistance; the significant improvement of DMA and thermal properties can also be the basis for the increase of wear resistance.

For the graphene-reinforced polyimide nanocomposite obtained in Example 5, the test shows that its mechanical properties, thermal stability, hardness, wear resistance, etc. are close to those of Examples 1-4, and far better than the comparison The polyimide material of Example 1 and the polyimide graphene oxide composite material of Comparative Examples 2-3.

Comparative example 2 The preparation technology of a kind of fluorinated treatment graphene reinforced polyimide composite material that this comparative example relates to comprises:

Fluorinated graphene (0.04g), 4,4 diaminodiphenyl ether (2.00g) and pyromellitic anhydride (2.18g) were placed in solvent N,N dimethylacetamide (30mL) to obtain a mixture liquid, mechanically stirred in a nitrogen atmosphere for 4 h under ice bath conditions to obtain polyamide prepolymer graphene nanocomposites, which were coated on steel sheets and heated in a vacuum drying oven for 80 The temperature was kept constant for 6 h to remove a large amount of solvent, and then heated at 80 °C, 135 °C, and 300 °C for 2 h at each constant temperature, and finally a fluorinated graphene-reinforced polyimide composite coating was obtained.

Comparative Example 3 The preparation process of a polyimide graphene oxide composite material involved in this comparative example includes:

4,4 diaminodiphenyl ether (2.00g) and pyromellitic anhydride (2.16g) were added to solvent N,N dimethylacetamide (40mL) to obtain a mixed solution, which was mechanically stirred under nitrogen atmosphere at room temperature 24h, polyamide prepolymer (PAA) was obtained, PAA (1g) and graphene oxide dispersion (5mg/mL) were added to solvent DMAC (5mL), sonicated for 6h, followed by mechanical stirring for 12h, and then at 80°C Uniformly dispersed graphene oxide reinforced polyimide composites were obtained by heating at constant temperature for 4 h, 120 °C and 300 °C for 2 h each.

The tests on mechanical properties, thermal stability, hardness, wear resistance and other aspects show that the properties of the material obtained in Comparative Example 2 are quite different from those of the materials obtained in Examples 1-5, which may be due to the fact that in the Comparative Example The surface of graphene is chemically modified and modified, which destroys the structure of graphene, so that it is inferior to Examples 1-5 in many properties, especially the improvement of mechanical properties and friction properties. In addition, the performance improvement of the materials obtained in Examples 1-5 is also more obvious than that of the materials obtained in Comparative Example 3. The reason may be that Comparative Example 3 directly uses unmodified graphene oxide as the filler. Moreover, the direct blending method is used, and graphene oxide cannot be uniformly dispersed in the composite material.

The above-mentioned embodiments are only used to help understand the core idea of the method of the present invention, and the descriptions thereof are specific and detailed, but should not be construed as a limitation on the scope of the patent of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can also be made, which all fall within the protection scope of the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Accordingly, the scope of protection of the present patent should be determined by the appended claims, not limited to the examples shown herein, but to be consistent with the principles and features disclosed herein.

Claims (21)

1. A graphene reinforced polyimide nano composite material is characterized by comprising 0.1-50 wt% of graphene two-dimensional nanosheets, 19.23-76.81 wt% of polyimide, and 0.05-25 wt% of polyaniline nanofibers and/or polyaniline nanoparticles; the polyaniline nano-fibers are 10-300 nm in diameter and 0.5-5 mu m in length, the polyaniline nano-particles are 50-500 nm in particle size, and at least part of the polyaniline nano-fibers and/or the polyaniline nano-particles are physically combined with the graphene two-dimensional nanosheets to form a compound.

2. The graphene reinforced polyimide nanocomposite according to claim 1, wherein: the graphene reinforced polyimide nano composite material is formed by compounding a graphene two-dimensional nano sheet, polyimide, polyaniline nano fiber and/or polyaniline nano particle.

3. The graphene reinforced polyimide nanocomposite according to claim 1, wherein: the content of the graphene two-dimensional nanosheet in the graphene reinforced polyimide nanocomposite is 0.25wt% -10 wt%.

4. The graphene reinforced polyimide nanocomposite according to claim 3, wherein: the content of the graphene two-dimensional nanosheet in the graphene reinforced polyimide nanocomposite is 0.25wt% -1 wt%.

5. The graphene reinforced polyimide nanocomposite according to claim 1, wherein: the graphene reinforced polyimide nano composite material comprises 0.25-1 wt% of graphene two-dimensional nano sheet, 65.38-76.35 wt% of polyimide and 0.25-1 wt% of polyaniline nano fiber and/or polyaniline nano particle.

6. The graphene reinforced polyimide nanocomposite according to claim 1, wherein: the mass ratio of the graphene two-dimensional nanosheets, the polyaniline nanofibers and/or the polyaniline nanoparticles to the polyimide is 0.15: 76.81-15: 65.38.

7. the graphene reinforced polyimide nanocomposite according to claim 6, wherein: the mass ratio of the graphene two-dimensional nanosheets, the polyaniline nanofibers and/or the polyaniline nanoparticles to the polyimide is 0.25: 76.35-1: 71.15.

8. the graphene reinforced polyimide nanocomposite according to claim 1, wherein: the polyaniline nanofiber is 10-100 nm in diameter and 0.5-2 mu m in length.

9. The graphene reinforced polyimide nanocomposite according to claim 1, wherein: the particle size of the polyaniline nanoparticles is 100-200 nm.

10. The graphene reinforced polyimide nanocomposite according to claim 1, wherein: the polyimide includes a condensation type aromatic polyimide.

11. The graphene reinforced polyimide nanocomposite according to claim 10, wherein: the polyimide is formed by in-situ polymerization of aromatic diamine and aromatic dianhydride.

12. The graphene reinforced polyimide nanocomposite according to claim 11, wherein: the aromatic diamine includes 4,4 diaminodiphenyl ether, 4 diaminobiphenyl or 3,4 diaminodiphenyl ether, and the aromatic dianhydride includes pyromellitic dianhydride, benzophenone dianhydride, biphenyl dianhydride or trimellitic anhydride.

13. The method of preparing the graphene-reinforced polyimide nanocomposite material according to any one of claims 1 to 12, comprising:

mixing graphene powder and/or graphene two-dimensional nanosheets and polyaniline nanofibers and/or polyaniline nanoparticles in a solvent to obtain a dispersion liquid of the graphene two-dimensional nanosheets;

mixing the dispersion liquid of the graphene two-dimensional nanosheet with aromatic diamine and aromatic dianhydride, carrying out in-situ polymerization on the aromatic diamine and the aromatic dianhydride to form a polyamide prepolymer/graphene composite, heating the polyamide prepolymer/graphene composite at 100-150 ℃ for 1-4 h, and heating at 200-300 ℃ for 1-4 h to carry out imidization reaction on the polyamide prepolymer, thereby obtaining the graphene-reinforced polyimide nanocomposite.

14. The method according to claim 13, characterized by comprising: mixing graphene powder and/or graphene two-dimensional nanosheets and polyaniline nanofibers and/or polyaniline nanoparticles in a solvent, and performing ultrasonic treatment to obtain a dispersion liquid of the graphene two-dimensional nanosheets.

15. The method of manufacturing according to claim 13, wherein: the mass ratio of the graphene powder to the polyaniline nanofiber and/or polyaniline nanoparticle is 1: 10-1: 0.1.

16. the method of claim 15, wherein: the mass ratio of the graphene powder to the polyaniline nanofiber and/or polyaniline nanoparticle is 1: 1-3: 1.

17. the method of manufacturing according to claim 16, wherein: the mass ratio of the graphene two-dimensional nanosheets to the polyaniline nanofibers and/or polyaniline nanoparticles is 1: 5-2: 1.

18. the method of claim 17, wherein: the mass ratio of the graphene two-dimensional nanosheets to the polyaniline nanofibers and/or polyaniline nanoparticles is 1: 1-2: 1.

19. the method according to claim 13, characterized by comprising: and sequentially heating the polyamide prepolymer/graphene composite at 100-120 ℃ and 150-170 ℃ for 1-3 h at constant temperature respectively, and then sequentially heating at 200-220 ℃, 250-270 ℃ and 300-320 ℃ for 1-2 h at constant temperature respectively to obtain the graphene reinforced polyimide nanocomposite.

20. The method of manufacturing according to claim 13, wherein: the solvent includes a high boiling polar organic solvent.

21. The method of claim 20, wherein: the solvent comprises dimethylformamide, N-methylpyrrolidone or dimethylacetamide.

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