Preparation method of graphene-based water-oxygen barrier film and graphene-based water-oxygen barrier film

Abstract

The application relates to the fields of material technology and instrument science, and discloses a preparation method of a graphene-based water-oxygen barrier film and the graphene-based water-oxygen barrier film. The graphene-based water-oxygen barrier film is prepared by combining an initiated chemical vapor deposition (iCVD) technology with a layer-by-layer self-assembly (LBL) technology, realizing high-quality transfer of graphene and in-situ construction of inorganic nanosheets, and having high barrier property, high light transmittance and good flexibility. By using the application, the problems of interface pollution and damage caused by traditional wet transfer in the preparation of the graphene-based barrier film, weak interlayer coupling and short penetration path in the subsequent multilayer stacking can be solved.

Description

Technical Field

[0001] This invention relates to the fields of materials technology and instrument science, and more specifically, to a method for preparing a graphene water-oxygen barrier membrane based on initiation chemical vapor deposition (iCVD) technology and the graphene-based water-oxygen barrier membrane. Background Technology

[0002] Graphene, as a novel two-dimensional nanomaterial, possesses theoretically excellent water and oxygen barrier properties, high optical transparency, and good flexibility, demonstrating enormous application potential in various fields such as flexible electronics, optoelectronic packaging, and food and pharmaceutical packaging. Theoretically, graphene, with its perfect crystal structure, can effectively block all gas molecules, including helium, making it an ideal ultrathin flexible barrier material, particularly suitable for flexible OLED packaging applications where stringent requirements exist for material thickness, transparency, and flexibility.

[0003] However, in actual industrial applications, the barrier properties of graphene films prepared by chemical vapor deposition (CVD) technology have not yet reached the theoretical expected values. The core limiting factor is the various defects generated during the preparation and transfer process: on the one hand, the graphene films prepared by CVD have intrinsic defects and surface wrinkles; on the other hand, during the graphene transfer process, problems such as polymer residue, film cracks and damage are easily introduced, which seriously damage the integrity of graphene and thus affect its barrier properties.

[0004] The graphene transfer process is a key factor affecting its final barrier performance. Traditional transfer processes often employ wet transfer methods, which typically require spin-coated polymers as a support layer for the graphene. However, due to insufficient wettability between the polymer solution and the graphene surface, non-conformal gaps easily form at the interface. These gaps can cause significant mechanical damage to the graphene during the transfer process, and the resulting cracks and defects become rapid channels for water vapor and oxygen permeation, drastically reducing the water and oxygen barrier effect of the graphene film.

[0005] To address the aforementioned issues, current research in this field primarily employs techniques such as multilayer graphene stacking, graphene surface functionalization, or the insertion of molecular layers at the graphene interface to attempt to improve the water and oxygen barrier properties of graphene films. While these methods can increase the water vapor transmission rate (WVTR) of graphene films by 10... - ³ to 10 -5 While the g / (m²·d) level is sufficient, there are generally significant technical shortcomings: it often requires sacrificing the thickness and optical transparency of the film, while significantly increasing the complexity of the process, resulting in a substantial increase in manufacturing costs, making it difficult to meet the actual needs of flexible OLED packaging for thin, light, highly transparent, low-cost, and simple processes.

[0006] Therefore, how to maximize the intrinsic water and oxygen barrier properties of single-layer graphene without relying on multi-layer graphene stacking structures, while taking into account the high transparency, thinness, and ease and economy of the film preparation process, has become a key scientific problem and technical challenge that urgently needs to be solved in the field of barrier materials for flexible OLED packaging. Summary of the Invention

[0007] In view of the above problems, the purpose of this invention is to provide a method for preparing a graphene-based water-oxygen barrier membrane and the graphene-based water-oxygen barrier membrane itself, so as to solve the problems of interface contamination and damage caused by traditional wet transfer in the preparation of existing graphene-based barrier membranes, as well as the weak interlayer coupling and short permeation paths in subsequent multilayer stacking. This invention aims to combine initiated chemical vapor deposition (iCVD) technology with layer-by-layer self-assembly (LBL) technology to achieve high-quality transfer of graphene and in-situ construction of inorganic nanosheets, so as to prepare a water-oxygen barrier membrane with high barrier properties, high light transmittance and good flexibility.

[0008] To achieve the above objectives, the present invention provides the following technical solutions.

[0009] In a first aspect, the present invention provides a method for preparing a graphene-based water-oxygen barrier membrane, comprising:

[0010] Graphene films were prepared on metal substrates.

[0011] The surface of the graphene film is pretreated;

[0012] A first polymer film was deposited on the surface of a pretreated graphene film using an initiation-based chemical vapor deposition technique.

[0013] The first polymer film is bonded to a flexible substrate by roll forming to obtain a composite structure; wherein the composite structure comprises, in sequence, the metal substrate, the graphene film, the first polymer film, and the flexible substrate;

[0014] The metal substrate of the composite structure is removed, and the surface of the graphene film is sequentially immersed in MMT colloidal solution, deionized water, LDH colloidal solution and deionized water to form an MMT / LDH nanocomposite layer on the surface of the graphene film. The above-mentioned immersion is repeated to obtain a composite nanosheet structure.

[0015] A graphene-based water and oxygen barrier film is obtained by depositing a second polymer film on the surface of the composite nanosheet structure using initiation chemical vapor deposition technology; wherein the graphene-based water and oxygen barrier film comprises, in sequence, the second polymer film, an MMT / LDH nanocomposite layer, a graphene film, a first polymer film, and a flexible substrate.

[0016] Alternatively, the metal substrate may be a copper substrate or a copper-nickel alloy substrate, wherein the copper-nickel alloy substrate is prepared by mixing copper and nickel in any proportion.

[0017] Alternatively, graphene films can be prepared on metal substrates using chemical vapor deposition.

[0018] Alternatively, the surface pretreatment of the graphene film may include: oxygen plasma modification of the surface of the graphene film, wherein the power used for modification is 20~80W and the time is 1~10s.

[0019] Alternatively, the thickness of both the first polymer film and the second polymer film can be 50~200nm.

[0020] Alternatively, both the first polymer film and the second polymer film are prepared by mixing any one or at least two of the monomers selected from 1,3,5-trivinyl-1,3,5-trimethylcyclotrisiloxane, 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane, ethylene glycol dimethacrylate, divinylbenzene, 1H,1H,2H,2H-perfluorodecyl acrylate, 1H,1H,2H,2H-perfluorooctyl acrylate, and hexafluorobutyl acrylate with the initiator di-tert-butyl peroxide in any proportion.

[0021] Alternatively, the flexible substrate can be a composite substrate formed by bonding a polymer substrate with an adhesive; wherein,

[0022] The polymer substrate is made of any one of the following polymers: polyethylene naphthalate, polyethylene terephthalate, polyimide, cyclic olefin copolymer, cyclic olefin polymer, and polyolefin elastomer; or it is made by mixing at least two polymers in any proportion; or it is made by stacking at least two polymers in any order.

[0023] The thickness of the polymer substrate is 5μm~100μm;

[0024] The adhesive is a polyacrylic acid material with a thickness of 1μm to 50μm and a peel strength of 0 to 20 N / 25mm.

[0025] Alternatively, an alternative approach is to remove the metal substrate of the composite structure using etching or electrochemical bubbling methods; wherein,

[0026] When the metal substrate of the composite structure is removed by etching, the etching solution is any one of sodium persulfate solution, potassium sulfate solution, ammonium persulfate solution, ferric chloride solution, hydrochloric acid solution or nitric acid solution, or at least two of them mixed in any proportion, and the concentration of the etching solution is 0.1 mol / L to 2.0 mol / L.

[0027] When removing the metal substrate of the composite structure using an electrochemical bubbling method, an electrochemical reaction is carried out with platinum or graphite as the anode and the metal substrate as the cathode; wherein...

[0028] The electrolyte is one of sodium hydroxide solution, potassium hydroxide solution, sodium nitrate solution, potassium nitrate solution, and ammonium nitrate solution, or at least two of them mixed in any proportion, and the concentration of the electrolyte is 0.5 mol / L to 5.0 mol / L.

[0029] Alternatively, an alternative approach is to sequentially immerse the surface of the graphene film in MMT colloidal solution, deionized water, LDH colloidal solution, and deionized water to form an MMT / LDH nanocomposite layer on the surface of the graphene film. This process is repeated in the above sequence to obtain the composite nanosheet structure.

[0030] The soaking time in both the MMT and the LDH colloidal solution was 1~24 h.

[0031] The soaking time in the deionized water is 5-30 minutes;

[0032] The number of cycles is 1 to 20.

[0033] The mass fraction of both the MMT colloidal solution and the LDH colloidal solution is 0.1~2.0%; wherein, the LDH powder is at least one of magnesium-aluminum layered double hydroxide, zinc-aluminum layered double hydroxide, calcium-aluminum layered double hydroxide, and lithium-aluminum layered double hydroxide, or a ternary layered double hydroxide composed of any two of the four divalent metal elements magnesium, zinc, calcium, and lithium and aluminum.

[0034] Secondly, the present invention provides a graphene-based water and oxygen barrier membrane, which is prepared by the above-mentioned method for preparing a graphene-based water and oxygen barrier membrane.

[0035] As can be seen from the above technical solution, the preparation method and the graphene-based water-oxygen barrier membrane provided by the present invention have the following advantages compared with the prior art:

[0036] (1) This invention modifies the surface of a graphene film on a metal substrate with oxygen plasma, and then deposits a first polymer film on the surface of the graphene film using iCVD technology. Compared with the traditional spin-coating method, the use of organic solvents can be avoided, and the thickness and functional groups of the polymer film deposited by iCVD technology can be precisely controlled. The modified graphene film and the reaction precursors (monomers, initiators) of the first polymer film are more easily combined, so that the polymer grown on its surface can be more closely attached to the graphene and form a good conformal structure.

[0037] (2) In this invention, during the process of bonding the first polymer film to the flexible substrate and removing the metal substrate of the composite structure, a continuous, gapless support is provided for the graphene film, ultimately achieving large-area, lossless transfer of graphene. To further improve the water and oxygen barrier performance of the monolayer graphene barrier film, this invention constructs multiple nanocomposite layers on the surface of the monolayer graphene film. Utilizing the abundant active groups on the surface of the nanosheets, strong interactions are formed with the polymer interface and adjacent nanosheets through hydrogen bonding, electrostatic attraction, etc., resulting in layer-by-layer self-assembly on the graphene film surface, forming a tortuous path. This effectively extends the diffusion path of water molecules and oxygen, significantly reducing the permeation rate of water vapor and oxygen, thereby further improving the barrier performance of the water and oxygen barrier film.

[0038] To achieve the foregoing and related objectives, one or more aspects of the invention include the features that will be described in detail below. The following description and accompanying drawings illustrate certain exemplary aspects of the invention. However, these aspects indicate only a few of the various ways in which the principles of the invention can be used. Furthermore, the invention is intended to encompass all such aspects and their equivalents. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 This is a flowchart illustrating the preparation method of the graphene-based water and oxygen barrier membrane according to Example 1 of the present invention.

[0041] Figure 2 This is a schematic diagram of the structure of the graphene-based water and oxygen barrier membrane prepared according to Example 1 of the present invention;

[0042] Figure 3 An optical image of a monolayer graphene barrier film transferred to a flexible substrate, prepared according to Example 1 of the present invention;

[0043] Figure 4 An optical image of a monolayer graphene barrier film transferred to a flexible substrate, prepared according to Comparative Example 1 of the present invention.

[0044] Figure 5 The results of water vapor transmission rate tests of the graphene-based water-oxygen barrier membranes prepared according to Example 1 and Comparative Examples 1 and 2 of the present invention are as follows:

[0045] Figure 6 The results of oxygen permeability tests of the graphene-based water-oxygen barrier membranes prepared according to Example 1 and Comparative Examples 1 and 2 of the present invention are compared. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0047] All patent and non-patent literature publications cited in this invention are incorporated herein by reference.

[0048] As used herein, the terms “comprising,” “including,” “containing,” “covering,” “having,” “with,” or any other variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, article of manufacture, or apparatus that includes a list of elements is not necessarily limited to those elements, but may include other elements not expressly listed or inherent to the process, method, article of manufacture, or apparatus. Furthermore, unless expressly stated otherwise, “or” means inclusive “or” rather than exclusive “or.” For example, condition A or B satisfies any of the following: A is real (or exists) and B is false (or does not exist); A is false (or does not exist) and B is real (or exists); and both A and B are real (or exist). The phrase “one or more” is intended to cover non-exclusive inclusion. For example, one or more A, B, and C means any of the following: A alone, B alone, C alone, a combination of A and B, a combination of B and C, a combination of A and C, or a combination of A, B, and C.

[0049] Additionally, the terms "an" or "a" are used to describe the elements and components described herein. This is done solely for convenience and to provide a general meaning regarding the scope of the invention. This description should be understood to include one or at least one, one or at least one, and the singular includes the plural unless explicitly stated otherwise.

[0050] To address the problems of interface contamination and damage caused by traditional wet transfer in the preparation of existing graphene-based barrier membranes, as well as the weak interlayer coupling and short permeation paths in subsequent multilayer stacking, this invention proposes a method for preparing a graphene-based water-oxygen barrier membrane and the graphene-based water-oxygen barrier membrane itself.

[0051] Initiated Chemical Vapor Deposition (iCVD), a low-temperature, dry vapor-phase polymerization process, can grow highly cross-linked polymer films with precisely controllable thickness and functional groups on the surface of graphene in situ. This in-situ grown polymer layer can form a tight conformal contact with graphene, providing support for the graphene during bonding to flexible substrates and subsequent etching of metal substrates, thereby achieving non-destructive transfer of graphene.

[0052] To further enhance barrier properties and meet the encapsulation requirements of flexible OLEDs (Organic Light-Emitting Diodes), this solution introduces inorganic nanosheets with high aspect ratio and extremely low gas permeability, such as montmorillonite (MMT) or layered double hydroxide (LDH). Using layer-by-layer assembly (LBL) technology, charged inorganic nanosheets are alternately deposited on the graphene / polymer surface. The abundant active groups (such as hydroxyl groups) on the nanosheet surface can form strong interactions with the polymer interface and adjacent nanosheets through hydrogen bonding, electrostatic attraction, and other mechanisms. This constructs a highly ordered, tightly stacked nanocomposite layer, forming a tortuous path that effectively extends the diffusion path of water molecules and oxygen, significantly reducing the permeation rate. This invention aims to combine initiation chemical vapor deposition (iCVD) technology with layer-by-layer self-assembly (LBL) technology to achieve high-quality transfer of graphene and in-situ construction of inorganic nanosheets, so as to prepare a water and oxygen barrier film with high barrier properties, high light transmittance and good flexibility for flexible OLED packaging.

[0053] like Figure 1 and Figure 2 As shown in the figure, the method for preparing the graphene-based water and oxygen barrier film provided by the present invention includes: S1: preparing a graphene film on a metal substrate;

[0054] S2: Pre-treat the surface of the graphene film;

[0055] S3: A first polymer film is deposited on the surface of a pretreated graphene film using an initiation-based chemical vapor deposition technique;

[0056] S4: The first polymer film is bonded to the flexible substrate by roll bonding to obtain a composite structure; wherein, the composite structure sequentially includes the metal substrate, the graphene film, the first polymer film and the flexible substrate;

[0057] S5: Remove the metal substrate of the composite structure, and immerse the surface of the graphene film in MMT colloidal solution, deionized water, LDH colloidal solution and deionized water in sequence, so that an MMT / LDH nanocomposite layer is formed on the surface of the graphene film. The single layer is used as a cycle unit and the above sequence is repeated to obtain a composite nanosheet structure.

[0058] S6: A second polymer film is deposited on the surface of the composite nanosheet structure by initiation chemical vapor deposition technology to obtain a graphene-based water and oxygen barrier film; wherein, the graphene-based water and oxygen barrier film comprises, in sequence, the second polymer film, an MMT / LDH nanocomposite layer, a graphene film, a first polymer film and a flexible substrate.

[0059] In S1, the metal substrate is a copper substrate or a copper-nickel alloy substrate, wherein the copper-nickel alloy substrate is prepared by mixing copper and nickel in any proportion. When growing graphene on a metal substrate by chemical vapor deposition, the metal substrate is preferably, but not limited to, a Cu, Ni, or alloy thereof metal foil that catalyzes graphene growth, or a Cu, Ni, or alloy thereof metal layer sputtered onto a sapphire substrate.

[0060] In step S2, the pretreatment of the graphene film surface includes: oxygen plasma modification of the graphene film surface, wherein the gas used is oxygen, the power used for modification is 20~80W, and the time is 1~10s. Specifically, when using oxygen to perform plasma modification on the graphene film surface, the power used is preferably, but not limited to, 20~80W, such as 20W, 40W, 60W, etc., and the modification time is preferably, but not limited to, 1~10s, such as 1s, 3s, 5s, etc.

[0061] In S3, the first polymer film deposited using iCVD technology is prepared by reacting any one of the monomers selected from 1,3,5-trivinyl-1,3,5-trimethylcyclotrisiloxane, 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane, ethylene glycol dimethacrylate, divinylbenzene, 1H,1H,2H,2H-perfluorodecyl acrylate, 1H,1H,2H,2H-perfluorooctyl acrylate, and hexafluorobutyl acrylate, or by mixing at least two of the above monomers in any proportion with the initiator di-tert-butyl peroxide.

[0062] Specifically, one or at least two of the aforementioned monomers are placed in separate heatable glass containers, and the initiator is placed in another separate glass container. The monomers are heated to volatilize in gaseous form, and the gas flow rate is controlled by a needle valve. Subsequently, the volatilized initiator gas is collected in the reaction chamber through its respective pipes. After passing through a heating filament, the initiator is converted into free radicals, which finally converge with the monomers on the surface of the modified graphene film and undergo a free radical polymer reaction to generate the first polymer film. The synthesis conditions of the polymer, such as monomer heating temperature, monomer flow rate, and hot filament temperature, are not particularly limited in this invention.

[0063] As a preferred embodiment of the present invention, a polymer film (first polymer film) with a thickness of 50~200nm is grown on the surface of the plasma-modified graphene film using iCVD. The thickness of the first polymer film is adjustable; in specific applications, the thickness of the first polymer film is preferably, but not limited to, 50~200nm, such as 50nm, 100nm, or 150nm.

[0064] In S4, the modified graphene film / metal substrate is placed in the iCVD reaction chamber, a first polymer film is grown on the surface of the graphene film, and then rolled and bonded to a flexible substrate to obtain a composite structure; wherein, the composite structure includes, from bottom to top, a metal substrate, a graphene film, a first polymer film and a flexible substrate.

[0065] The flexible substrate is a composite substrate formed by bonding a polymer substrate with an adhesive. The polymer substrate is made of any one of the following polymers: polyethylene naphthalate, polyethylene terephthalate, polyimide, cyclic olefin copolymer, cyclic olefin polymer, and polyolefin elastomer; or it can be made by mixing at least two polymers in any proportion; or it can be made by stacking at least two polymers in any order. The thickness of the polymer substrate is 5 μm to 100 μm. The adhesive is a polyacrylic acid material with a thickness of 1 μm to 50 μm and a peel strength of 0 to 20 N / 25 mm.

[0066] Specifically, the graphene / metal substrate with the first polymer film grown is roll-pressed onto a flexible substrate with adhesive, with the first polymer film in contact with the adhesive on the flexible substrate. The polymer substrate in the flexible substrate provides mechanical support for the barrier film, facilitating practical operation; the adhesive increases the adhesion between the first polymer film and the polymer substrate, helping to reduce the gap between them. The polymer substrate, adhesive, and first polymer film of the flexible substrate are all part of the barrier film.

[0067] The flexible substrate contains a polymer substrate composed of one or more of PEN, PET, PI, COC, COP, and POE. The thickness of the polymer substrate is 5μm to 100μm. Those skilled in the art can select a suitable polymer film thickness according to actual needs, such as 5μm, 25μm, or 50μm. The adhesive in the flexible substrate is a polyacrylic acid material. The thickness of the polyacrylic acid layer is preferably, but not limited to, 1μm to 50μm, and the peel strength is preferably, but not limited to, 0 to 20 N / 25mm. Those skilled in the art can select a suitable polyacrylic acid layer thickness and peel strength according to actual needs. For example, the thickness of the acrylic layer can be 5μm, 25μm, or 50μm, and the peel strength can be 0.8 N / 25mm, 2 N / 25mm, or 10 N / 25mm.

[0068] In S5, the metal substrate of the composite structure is removed to obtain a single-layer graphene barrier film; wherein the single-layer graphene barrier film comprises a graphene film, a first polymer film and a flexible substrate in sequence.

[0069] In embodiments of the present invention, the metal substrate of the composite structure is removed by etching or electrochemical bubbling; wherein, when etching is used to remove the metal substrate of the composite structure, the etching solution is any one of sodium persulfate solution, potassium sulfate solution, ammonium persulfate solution, ferric chloride solution, hydrochloric acid solution or nitric acid solution or at least two of them mixed in any proportion, and the concentration of the etching solution is 0.1 mol / L to 2.0 mol / L.

[0070] When the metal substrate of the composite structure is removed by electrochemical bubbling, an electrochemical reaction is carried out with platinum or graphite as the anode and the metal substrate as the cathode; wherein the electrolyte is one of sodium hydroxide solution, potassium hydroxide solution, sodium nitrate solution, potassium nitrate solution, and ammonium nitrate solution or at least two of them mixed in any proportion, and the concentration of the electrolyte is 0.5 mol / L to 5.0 mol / L.

[0071] Specifically, when removing the metal substrate using etching, the etching solution used is one or more of the following: sodium sulfate solution, potassium sulfate solution, ammonium persulfate solution, ferric chloride solution, hydrochloric acid solution, or nitric acid solution. The concentration of the etching solution is preferably, but not limited to, 0.1 mol / L to 2.0 mol / L. When removing the metal substrate using bubbling, platinum or graphite can be used as the anode, and the metal substrate as the cathode. The concentration of the electrolyte is preferably, but not limited to, 0.5 mol / L to 5.0 mol / L. After the metal substrate is completely etched or separated by bubbling, the resulting film is washed in deionized water to remove residual etching solution or electrolyte, and finally dried to obtain a single-layer graphene barrier film.

[0072] In an embodiment of the present invention, montmorillonite (MMT) powder and layered double metal hydroxide (LDH) powder are added to deionized water and stirred thoroughly. After ultrasonic exfoliation, stirring, and centrifugation, the supernatant is taken to obtain montmorillonite colloidal solution and layered double metal hydroxide colloidal solution.

[0073] As a preferred embodiment of the present invention, the mass fraction of MMT colloidal solution and LDH colloidal solution is 0.1~2.0%.

[0074] The LDH powder is selected from at least one of magnesium-aluminum layered double hydroxide, zinc-aluminum layered double hydroxide, calcium-aluminum layered double hydroxide, and lithium-aluminum layered double hydroxide, or is a ternary layered double hydroxide composed of any two of the four divalent metal elements (magnesium, zinc, calcium, and lithium) and aluminum. The MMT powder is a commonly used sodium-based montmorillonite powder, and this invention does not impose any particular limitation.

[0075] Specifically, firstly, different masses of MMT powder or LDH powder are weighed, and an equal amount of deionized water is added. The mixture is then thoroughly stirred to ensure uniform dispersion. Ultrasonic exfoliation is performed using an ultrasonic disperser, and the resulting solutions are further stirred until homogeneous. Finally, centrifugation is used to obtain supernatants with different mass fractions, which are respectively MMT colloidal solutions and LDH colloidal solutions. Specific parameters are not particularly limited in this invention. The preferred, but not limited, mass fraction of the MMT and LDH colloidal solutions is 0.1% to 2.0%. The LDH powder used is composed of colorless metal ions, resulting in a white powder. After exfoliation, the nanosheets exhibit good light transmittance, thus achieving a balance between good barrier properties and light transmittance.

[0076] In S5, the surface of a single-layer graphene barrier film was sequentially immersed in MMT colloidal solution, deionized water, LDH colloidal solution, and then in deionized water. This process facilitated the adsorption of two nanosheets (MMT / LDH nanosheets) on the graphene film surface. The immersion was repeated multiple times in this sequence to construct the multilayer nanosheets. The immersion time in MMT and LDH colloidal solutions was 1–24 h; the immersion time in deionized water was 5–30 min; and the number of cycles was 1–20.

[0077] Specifically, the obtained monolayer graphene barrier film is immersed in a prepared MMT colloidal solution to form a layer of MMT nanosheets. The immersion time is preferably, but not limited to, 1-24 hours. Then, the barrier film with the MMT nanosheets adsorbed is immersed in deionized water for a certain period of time, preferably, but not limited to, 5-30 minutes, to wash away the MMT colloidal solution that is not completely adsorbed on the surface and prevent residual MMT colloidal solution from contaminating the LDH colloidal solution. Subsequently, the washed barrier film is placed in an LDH colloidal solution to form a layer of LDH nanosheets, preferably, but not limited to, 1-24 hours. Then, it is immersed in deionized water again to wash away the residual LDH solution, preferably, but not limited to, 5-30 minutes. In this way, the alternating adsorption process of one layer of MMT and one layer of LDH nanosheets is completed, and this is considered one cycle. The above-mentioned immersion process is repeated multiple times to complete the construction of multiple nanosheet layers on the graphene surface. The number of cycles is preferably, but not limited to, 1-20 times.

[0078] In step S6, after the barrier film (composite nanosheet structure) with adsorbed multilayer nanosheets is dried, it is placed in the iCVD reaction chamber. A polymer film (second polymer film) is grown on the surface of the MMT / LDH nanocomposite layer using iCVD technology as a protective layer to obtain a graphene-based water and oxygen barrier film. The thickness, deposition method, and composition of the second polymer film are the same as those of the first polymer film.

[0079] Specifically, after the obtained monolayer graphene barrier film alternately adsorbs multiple layers of MMT and LDH nanosheets, it is dried and then placed back into the iCVD reaction chamber. Because the hydrophilicity and hydrophobicity of the barrier film surface change after the adsorption of inorganic nanosheets, a hydrophobic polymer film is grown on the nanosheet surface, which makes the barrier film surface highly hydrophobic, and at the same time can protect the internal nanosheet structure and enhance the barrier film's resistance to bending.

[0080] In an embodiment of the present invention, a graphene-based water and oxygen barrier film is prepared by the above preparation method and applied to flexible OLED packaging.

[0081] The technical solution of the present invention will be further described in detail below with reference to several preferred embodiments and accompanying drawings. This embodiment is implemented on the premise of the technical solution of the invention, and provides detailed implementation methods and specific operation processes. However, the protection scope of the present invention is not limited to the following embodiments.

[0082] Unless otherwise specified, the experimental materials used in the examples below can be purchased from conventional biochemical reagent companies.

[0083] Prepare three 10cm×10cm graphene sheets grown on a copper-nickel substrate, labeled as copper-nickel graphene No. 1, copper-nickel graphene No. 2, and copper-nickel graphene No. 3.

[0084] Example 1

[0085] The graphene film No. 1 grown on a copper-nickel substrate was treated as follows:

[0086] Step S1: The surface of the graphene film grown on the copper-nickel substrate is modified with oxygen plasma at a power of 40W for a time of 5s.

[0087] Step S2: The modified copper-nickel substrate-graphene film was placed in the iCVD reaction chamber. 1,3,5-trivinyl-1,3,5-trimethylcyclotrisiloxane monomer and di-tert-butyl peroxide initiator were selected as the polymer film reaction raw materials. The monomer and initiator were placed in separate glass jars. The monomer jar was heated to 70°C, and the initiator jar was kept at room temperature. The flow rates of the monomer and initiator volatile gases were controlled by needle valves, resulting in an initiator flow rate of 0.5 sccm (standard mL / min) and a monomer flow rate of 1.25 sccm. The hot filament temperature was set to 210°C, and the sample stage temperature in the reaction chamber was set to 40°C. The pressure in the reaction chamber was controlled at 400 mTorr by controlling the butterfly valve. The thickness of the polymer film deposited on the graphene surface was adjusted by controlling the growth time. Under these conditions, after 1 hour of growth, the thickness of the first polymer film was 150 nm. The copper-nickel substrate-graphene film, after the first polymer film has been grown, is roll-pressed onto a flexible polyethylene terephthalate (PET) substrate. The first polymer film is in contact with the polyacrylic acid layer in the PET flexible substrate to obtain a composite structure. The composite structure consists of a copper-nickel substrate, a graphene film, a first polymer film, and a flexible substrate (polyacrylic acid layer and PET).

[0088] Step S3: Place the composite structure in a sodium persulfate etching solution of mol / L. After the metal foil (copper-nickel substrate) is completely etched, rinse it several times in deionized water to remove the residual etching solution and obtain a single-layer graphene barrier film. The single-layer graphene barrier film includes a graphene film, a first polymer film and a flexible substrate from bottom to top. Place the cleaned barrier film in a vacuum drying oven at 60°C and dry for 8 hours to obtain the No. 1 single-layer graphene barrier film.

[0089] Step S4: Add montmorillonite powder and magnesium aluminum layered bimetallic hydroxide powder to deionized water and stir thoroughly. After ultrasonic exfoliation, stirring and centrifugation, take the supernatant to obtain a 1% montmorillonite colloidal solution and a 0.5% magnesium aluminum layered bimetallic hydroxide colloidal solution.

[0090] Step S5: The surface of the monolayer graphene barrier film obtained in step S3 is sequentially immersed in the montmorillonite colloidal solution obtained in step S4, deionized water, the magnesium-aluminum layered bimetallic hydroxide colloidal solution obtained in step S4, and deionized water for 2 hours, 15 minutes, 2 hours, and 15 minutes, respectively. This constitutes one cycle, and the above process is repeated for a total of five cycles of adsorption.

[0091] Step S6: After drying the barrier film after adsorbing the multilayer nanosheets, place it in the iCVD reaction chamber and use iCVD to grow a polymer film (second polymer film) on the surface of the nanosheet layer as a protective layer. The reaction raw materials used are 1,3,5-trivinyl-1,3,5-trimethylcyclotrisiloxane and di-tert-butyl peroxide. The reaction conditions are the same as in step 2, and the growth thickness is controlled at 150 nm. Finally, a graphene-based water and oxygen barrier film is obtained.

[0092] Comparative Example 1

[0093] The graphene grown on a copper-nickel substrate No. 2 was treated as follows:

[0094] Step S1: No treatment is performed on the surface of the graphene grown on the copper-nickel substrate;

[0095] Step S2: The modified copper-nickel substrate-graphene film was placed in the iCVD reaction chamber. 1,3,5-trivinyl-1,3,5-trimethylcyclotrisiloxane monomer and di-tert-butyl peroxide initiator were selected as the polymer film reaction raw materials. The monomer and initiator were placed in separate glass jars. The monomer jar was heated to 70°C, and the initiator jar was kept at room temperature. The flow rates of the monomer and initiator volatile gases were controlled by needle valves, resulting in an initiator flow rate of 0.5 sccm and a monomer flow rate of 1.25 sccm. The hot filament temperature was set to 210°C, and the sample stage temperature in the reaction chamber was set to 40°C. The pressure in the reaction chamber was controlled at 400 mTorr by a butterfly valve. The thickness of the polymer film deposited on the graphene surface was adjusted by controlling the growth time. Under these conditions, after 1 hour of growth, the thickness of the first polymer film was 150 nm. The copper-nickel substrate-graphene film, after the first polymer film has been grown, is roll-pressed onto a flexible polyethylene terephthalate (PET) substrate. The first polymer film is in contact with the polyacrylic acid layer in the PET flexible substrate to obtain a composite structure. The composite structure, from bottom to top, includes a copper-nickel substrate, a graphene film, a first polymer film, and a flexible substrate (polyacrylic acid layer and PET).

[0096] Step S3: Place the composite structure in a 1 mol / L sodium persulfate etching solution. After the metal foil is completely etched, rinse it several times in deionized water to remove the residual etching solution and obtain a single-layer graphene barrier film. The single-layer graphene barrier film includes a graphene film, a first polymer film and a flexible substrate from bottom to top. Place the cleaned barrier film in a vacuum drying oven at 60°C and dry it for 8 hours to obtain the No. 2 single-layer graphene barrier film.

[0097] Step S4: Add montmorillonite powder and magnesium aluminum layered bimetallic hydroxide powder to deionized water and stir thoroughly. After ultrasonic exfoliation, stirring and centrifugation, take the supernatant to obtain a 1% montmorillonite colloidal solution and a 0.5% magnesium aluminum layered bimetallic hydroxide colloidal solution.

[0098] Step S5: The surface of the monolayer graphene barrier film obtained in step S3 is sequentially immersed in the montmorillonite colloidal solution obtained in step S4, deionized water, the magnesium-aluminum layered bimetallic hydroxide colloidal solution obtained in step S4, and deionized water for 2 hours, 15 minutes, 2 hours, and 15 minutes, respectively. This constitutes one cycle, and the above process is repeated for a total of five cycles of adsorption.

[0099] Step S6: After drying the barrier film after adsorbing the multilayer nanosheets, place it in the iCVD reaction chamber and use iCVD to grow a polymer film (second polymer film) on the surface of the nanosheet layer as a protective layer. The reaction raw materials used are 1,3,5-trivinyl-1,3,5-trimethylcyclotrisiloxane and di-tert-butyl peroxide. The reaction conditions are the same as in step 2, and the growth thickness is controlled at 150 nm. Finally, a graphene-based water and oxygen barrier film is obtained.

[0100] The monolayer graphene barrier films obtained in step 3 of Example 1 and Comparative 1 were subjected to optical microscopy tests, such as... Figure 3 and Figure 4 As shown, the single-layer graphene transferred in Example 1 of the present invention showed no obvious damage, while the single-layer graphene transferred in Comparative Example 1 showed large-area damage.

[0101] Comparative Example 2

[0102] The graphene film No. 3 grown on a copper-nickel substrate was treated as follows:

[0103] Step S1: The surface of the graphene film grown on the copper-nickel substrate is modified with oxygen plasma at a power of 40W for a time of 5s.

[0104] Step S2: The modified copper-nickel substrate-graphene film was placed in the iCVD reaction chamber. 1,3,5-trivinyl-1,3,5-trimethylcyclotrisiloxane monomer and di-tert-butyl peroxide initiator were selected as the polymer film reaction raw materials. The monomer and initiator were placed in separate glass jars. The monomer jar was heated to 70°C, and the initiator jar was kept at room temperature. The flow rates of the monomer and initiator volatiles were controlled by needle valves, resulting in an initiator flow rate of 0.5 sccm (standard mL / min) and a monomer flow rate of 1.25 sccm. The hot filament temperature was set to 210°C, and the sample stage temperature in the reaction chamber was set to 40°C. The pressure in the reaction chamber was controlled at 400 mTorr by controlling the butterfly valve. The thickness of the polymer film deposited on the graphene surface was adjusted by controlling the growth time. Under these conditions, after 1 hour of growth, the thickness of the first polymer film was 150 nm. The copper-nickel substrate-graphene film, after the first polymer film has been grown, is roll-pressed onto a flexible polyethylene terephthalate (PET) substrate. The first polymer film is in contact with the polyacrylic acid layer in the PET flexible substrate to obtain a composite structure. The composite structure consists of a copper-nickel substrate, a graphene film, a first polymer film, and a flexible substrate (polyacrylic acid layer and PET).

[0105] Step S3: Place the composite structure in a 1 mol / L sodium persulfate etching solution. After the metal foil (copper-nickel substrate) is completely etched, rinse it several times in deionized water to remove the residual etching solution and obtain a single-layer graphene barrier film. The single-layer graphene barrier film includes a graphene film, a first polymer film and a flexible substrate from bottom to top. Place the cleaned barrier film in a vacuum drying oven at 60°C and dry for 8 hours to obtain the No. 3 single-layer graphene barrier film.

[0106] Step S4: After drying the No. 3 monolayer graphene barrier film, place it in the iCVD reaction chamber and use iCVD to grow a polymer film (second polymer film) on the surface of the nanosheet as a protective layer. The reaction raw materials used are 1,3,5-trivinyl-1,3,5-trimethylcyclotrisiloxane and di-tert-butyl peroxide. The reaction conditions are the same as in step 2, and the growth thickness is controlled at 150 nm. Finally, a graphene-based water and oxygen barrier film is obtained.

[0107] like Figure 5 and Figure 6As shown, Example 1 of this invention combines initiated chemical vapor deposition (iCVD) with layer-by-layer self-assembly (LBL) technology, and the graphene-based water-oxygen barrier film prepared by oxygen plasma modification on the surface of a graphene film on a metal substrate exhibits significantly better water vapor and oxygen barrier performance than the graphene-based water-oxygen barrier films prepared in Comparative Examples 1 and 2. This is mainly because the oxygen plasma-modified graphene used in this application allows for a denser and more uniform iCVD polymer film grown on its surface, enabling gapless contact between the grown polymer film and the graphene, effectively improving the integrity of graphene transfer, thereby reducing water vapor and oxygen permeation sites. Simultaneously, the self-assembled inorganic nanosheets construct a tortuous path, further enhancing the barrier film's barrier performance.

[0108] The above are merely preferred embodiments of the present invention and do not limit the scope of protection of the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any changes, modifications, substitutions, integrations, and parameter alterations to these embodiments within the spirit and principles of the present invention, achieved through conventional substitutions or by achieving the same function without departing from the principles and spirit of the present invention, fall within the scope of protection of the present invention.

Claims

1. A method for preparing a graphene-based water-oxygen barrier membrane, characterized in that, include: Graphene films were prepared on metal substrates. The surface of the graphene film is pretreated; wherein the surface of the graphene film is modified with oxygen plasma, the power of which is 20~80W and the time is 1~10s. A first polymer film was deposited on the surface of a pretreated graphene film using an initiation-based chemical vapor deposition technique. The first polymer film is bonded to a flexible substrate by roll forming to obtain a composite structure; wherein the composite structure comprises, in sequence, the metal substrate, the graphene film, the first polymer film, and the flexible substrate; The metal substrate of the composite structure is removed, and the surface of the graphene film is sequentially immersed in MMT colloidal solution, deionized water, LDH colloidal solution and deionized water to form an MMT / LDH nanocomposite layer on the surface of the graphene film. The above-mentioned immersion is repeated to obtain a composite nanosheet structure. A graphene-based water and oxygen barrier film is obtained by depositing a second polymer film on the surface of the composite nanosheet structure using initiation chemical vapor deposition technology; wherein, the graphene-based water and oxygen barrier film includes the second polymer film, an MMT / LDH nanocomposite layer, a graphene film, a first polymer film, and a flexible substrate.

2. The method for preparing the graphene-based water-oxygen barrier membrane according to claim 1, characterized in that, The metal substrate is a copper substrate or a copper-nickel alloy substrate, wherein the copper-nickel alloy substrate is prepared by mixing copper and nickel in any proportion.

3. The method for preparing the graphene-based water-oxygen barrier membrane according to claim 1, characterized in that, Graphene films were prepared on metal substrates using chemical vapor deposition.

4. The method for preparing the graphene-based water-oxygen barrier membrane according to claim 1, characterized in that, The thickness of both the first polymer film and the second polymer film is 50~200nm.

5. The method for preparing the graphene-based water-oxygen barrier membrane according to claim 1, characterized in that, Both the first polymer film and the second polymer film are prepared by mixing any one or at least two of the monomers selected from 1,3,5-trivinyl-1,3,5-trimethylcyclotrisiloxane, 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane, ethylene glycol dimethacrylate, divinylbenzene, 1H,1H,2H,2H-perfluorodecyl acrylate, 1H,1H,2H,2H-perfluorooctyl acrylate, and hexafluorobutyl acrylate with the initiator di-tert-butyl peroxide in any proportion.

6. The method for preparing the graphene-based water-oxygen barrier membrane according to claim 1, characterized in that, The flexible substrate is a composite substrate formed by bonding a polymer substrate with an adhesive; wherein... The polymer substrate is made of any one of the following polymers: polyethylene naphthalate, polyethylene terephthalate, polyimide, cyclic olefin copolymer, cyclic olefin polymer, and polyolefin elastomer; or it is made by mixing at least two polymers in any proportion; or it is made by stacking at least two polymers in any order. The thickness of the polymer substrate is 5μm~100μm; The adhesive is a polyacrylic acid material with a thickness of 1μm to 50μm and a peel strength of 0 to 20 N / 25mm.

7. The method for preparing the graphene-based water-oxygen barrier membrane according to claim 1, characterized in that, The metal substrate of the composite structure is removed using etching or electrochemical bubbling methods; wherein, When the metal substrate of the composite structure is removed by etching, the etching solution used is any one of sodium persulfate solution, potassium sulfate solution, ammonium persulfate solution, ferric chloride solution, hydrochloric acid solution or nitric acid solution, or at least two of them mixed in any proportion, and the concentration of the etching solution is 0.1 mol / L to 2.0 mol / L. When removing the metal substrate of the composite structure using an electrochemical bubbling method, an electrochemical reaction is carried out with platinum or graphite as the anode and the metal substrate as the cathode; wherein... The electrolyte used is one of sodium hydroxide solution, potassium hydroxide solution, sodium nitrate solution, potassium nitrate solution, and ammonium nitrate solution, or at least two of them mixed in any proportion, and the concentration of the electrolyte is 0.5 mol / L to 5.0 mol / L.

8. The method for preparing the graphene-based water-oxygen barrier membrane according to claim 1, characterized in that, The graphene film surface is sequentially immersed in MMT colloidal solution, deionized water, LDH colloidal solution, and deionized water to form an MMT / LDH nanocomposite layer on the surface of the graphene film. This process is repeated in the same order to obtain the composite nanosheet structure. The soaking time in both the MMT and the LDH colloidal solution was 1~24 h. The soaking time in the deionized water is 5-30 minutes; The number of cycles is 1 to 20. The mass fraction of both the MMT colloidal solution and the LDH colloidal solution is 0.1~2.0%; wherein, the LDH powder is at least one of magnesium-aluminum layered double hydroxide, zinc-aluminum layered double hydroxide, calcium-aluminum layered double hydroxide, and lithium-aluminum layered double hydroxide, or a ternary layered double hydroxide composed of any two of the four divalent metal elements magnesium, zinc, calcium, and lithium and aluminum.

9. A graphene-based water-oxygen barrier membrane, characterized in that, The graphene-based water and oxygen barrier membrane was prepared using the preparation method described in any one of claims 1-8.

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