A self-repairing hydrogen barrier composite coating for hydrogen storage or transport devices and its preparation method and application

Abstract

The present application relates to a kind of self-repairing hydrogen barrier composite coating for hydrogen storage or transport device and its preparation method and application, belong to hydrogen energy storage and transport material technical field.The coating adopts double-layer structure, is composed of primer and humidity response microcapsule self-repairing barrier layer.Humidity response microcapsule is formed by the capsule core containing polyurethane prepolymer and the hybrid capsule shell formed by polyurethane and siloxane, with good hydrogen barrier property and environmental response characteristics.Under certain humidity environment, microcapsule is excited to release capsule core material, and in-situ self-repairing is realized.The present application breaks through the problem that traditional hydrogen barrier coating lacks repair ability, and has wide application prospect in improving the safety of hydrogen transport and storage system.

Description

Technical Field

[0001] This invention relates to a self-healing hydrogen barrier composite coating for hydrogen storage or transportation devices, its preparation method and application, belonging to the field of hydrogen energy storage and transportation materials technology. Background Technology

[0002] With the development of the hydrogen energy industry, the safe and controllable storage and transportation of hydrogen has become a crucial factor affecting its development. This places higher demands on the safety, durability, and intelligence of hydrogen storage and transportation systems. Self-healing hydrogen barrier materials, through the introduction of environmentally responsive microcapsule technologies, provide key support for the large-scale and safe application of hydrogen energy and represent an important development direction for future hydrogen energy equipment materials.

[0003] Currently, there is considerable research on high hydrogen barrier coatings. For example, patent CN202111481773.2 uses ultrasonic atomization equipment to avoid contact and cross-contamination between polyethyleneimine and graphene oxide dispersions, and the prepared graphene oxide / polyethyleneimine self-assembled film has high hydrogen barrier performance. Patent CN202110914621.0 proposes a composite hydrogen barrier coating, in which the outer micron-sized TiN coating is a "hydrogen barrier layer" to block the penetration of hydrogen atoms; and the inner nano-sized TiC coating is a "hydrogen storage layer" to capture hydrogen atoms, thus realizing the hydrogen barrier function of the composite coating. This invention uses chemical vapor deposition to prepare a composite coating with high density and few defects, significantly improving the hydrogen barrier performance of stainless steel materials.

[0004] However, current research mainly focuses on improving the hydrogen barrier capacity of materials, neglecting the issue of microcracks caused by long-term hydrogen erosion leading to decreased hydrogen barrier performance and even the risk of hydrogen leakage. Therefore, research on intelligent responsive self-healing hydrogen barrier materials is of great significance. In existing technologies, polyurethane membranes, commonly used in repair materials, can be used to separate H2 and CO2. Furthermore, the literature (Azizi Morteza, Mousavi Seyyed Abbas. CO2 / H2 separation using a highly permeable polyurethane membrane: Molecular dynamics simulation[J]. Journal of Molecular Structure, 2015, 1100) shows that polyurethane membranes have the highest hydrogen diffusion and permeation coefficients. Therefore, polyurethane materials actually achieve hydrogen permeation (which is the opposite of the requirement for hydrogen barrier). Thus, the combined use of polyurethane self-healing materials and hydrogen barrier materials presents technical challenges.

[0005] Therefore, the development of intelligent response self-healing hydrogen barrier materials faces technical challenges such as improving barrier capacity and stability, achieving controllable repair, and increasing the number of repair cycles. Summary of the Invention

[0006] The purpose of this invention is to provide a self-healing hydrogen barrier composite coating for hydrogen storage or transportation devices, its preparation method, and its application. This coating has strong hydrogen barrier capability, and its humidity-responsive self-healing function can promptly close leakage channels. It has the advantages of extending the service life of the hydrogen barrier coating and improving the safety of hydrogen use, and has good application prospects in hydrogen storage and transportation.

[0007] This invention provides a method for preparing a self-healing hydrogen barrier composite coating for hydrogen storage or transportation devices. The coating has a high hydrogen barrier capability in a dry environment and can both block hydrogen and achieve intelligent response self-healing function in a certain humidity environment (40-70%).

[0008] The present invention also discloses the application of a self-healing hydrogen barrier composite coating for hydrogen storage or transportation devices in hydrogen energy storage and transportation.

[0009] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0010] A self-healing hydrogen barrier composite coating for hydrogen storage or transportation devices includes a two-layer structure consisting of a humidity-responsive microcapsule self-healing barrier layer and a base layer, wherein the humidity-responsive microcapsules have a polyurethane prepolymer as the core and the polyurethane and siloxane form a hybrid shell.

[0011] The base coating enhances the bonding strength between the humidity-responsive microcapsule self-healing barrier layer and the hydrogen storage or transport device, thereby improving mechanical properties. Without the base coating, the bonding between the humidity-responsive microcapsule self-healing barrier layer and the hydrogen storage or transport device is not strong enough, making it more prone to detachment. Furthermore, the base coating also acts as a hydrogen barrier.

[0012] The humidity-responsive microcapsule self-healing barrier layer is prepared by the following steps:

[0013] S01, mix polyimide emulsion with a solid content of 25~40wt%, polyvinyl alcohol, coupling agent and deionized water evenly in a mass ratio of 1 : (0.04~0.07) : (0.02~0.03) : 4, dip and coat it on the inner wall of the substrate, dry it and cure it at 160~180℃ to form a base coating on the substrate;

[0014] In a solvent at 60-80℃, 8-12 wt% ethylene-vinyl alcohol copolymer is added and stirred thoroughly to form a transparent ethylene-vinyl alcohol copolymer solution. Polyether ether ketone powder, humidity-responsive self-healing microcapsules, and a compound dispersant are ultrasonically dispersed into the ethylene-vinyl alcohol copolymer solution. The mass ratio of ethylene-vinyl alcohol copolymer, polyether ether ketone powder, humidity-responsive self-healing microcapsules, and compound dispersant is 1 : (0.4-0.6) : (0.22-0.3) : (0.03-0.05). 0.3-1.5 wt% silane coupling agent is added dropwise under continuous stirring to obtain a mixed coating liquid. The mixed coating liquid is applied to the base coat of the substrate. After drying, it is heat-treated at 130-160℃ for 10-30 minutes to finally form a humidity-responsive microcapsule self-healing barrier layer.

[0015] Before step S01, the substrate is subjected to sandblasting and pickling to remove oxide scale and impurities; the substrate is a stainless steel pipe substrate or a steel hydrogen storage tank.

[0016] The coupling agent described in S01 is one or more of γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-epoxypropyltriethoxysilane, and isopropyltris(dioctylpyrophosphate)titanate.

[0017] The preparation of the humidity-responsive self-healing microcapsules described in S02 includes the following steps:

[0018] Step a) In a nitrogen atmosphere at 20-40°C, 15-25 wt% of polyol and isocyanate are added to dichloromethane, followed by 0.05-0.5 wt% of triethylenediamine. The mixture is stirred continuously for 0.5-4 h to obtain a polyurethane prepolymer. The polyurethane prepolymer is dissolved in ethyl acetate, and 0.3-1.5 wt% of silane coupling agent is added and mixed evenly to obtain an oil phase. The molar ratio of the hydroxyl groups of the polyol to the -NCO groups of the isocyanate in step a is 1:(1.8-2.8).

[0019] Step b) Dissolve 0.5-2.5 wt% polyvinyl alcohol in water, add 5-10 wt% polyol and 5-20 wt% tetraethyl orthosilicate, and adjust the pH of the aqueous phase to 4-5 using 9-10 g / ml dilute hydrochloric acid; under strong shear stirring, slowly add the oil phase obtained in step a) dropwise to the aqueous phase, stirring until a uniform emulsion is formed, ensuring that the molar ratio of the residual -NCO groups of isocyanate in the oil phase to the hydroxyl groups of the polyol in the aqueous phase of step b is 1:(0.2-0.4); after stirring at 40-60℃ for 4-8 h, cool the system to room temperature, wash 5-6 times alternately with deionized water and ethanol, centrifuge, and vacuum dry to obtain stable microcapsules; wherein the microcapsules contain free NCO.

[0020] The residual -NCO groups of isocyanate in the oil phase obtained in step a refer to the theoretical residual -NCO groups. For example, when the molar ratio of the hydroxyl group of the polyol to the -NCO group of the isocyanate in step a is 1:1.8, the number of moles of the hydroxyl group of the polyol in step a is assumed to be 1 part, the number of moles of the -NCO group of the isocyanate is 1.8 parts, and the number of moles of the theoretical residual -NCO group is 0.8 parts.

[0021] The mass ratio of ethylene-vinyl alcohol copolymer, polyetheretherketone powder, and humidity-responsive self-healing microcapsules is 1 : (0.4~0.6) : (0.22~0.3). This ratio, combined with the specific preparation process, enables the final coating to have high hydrogen barrier capability and barrier stability, achieving controllable repair.

[0022] The ratio of ethylene-vinyl alcohol copolymer to humidity-responsive self-healing microcapsules is crucial for controlling the repair reaction rate and reducing the formation of pores or hydrogen permeation channels during self-healing. During self-healing, the release of the core repair agent alters the internal structure of the coating, easily leading to the formation of pores and even hydrogen permeation channels. However, the covalent bonding between the hydroxyl groups of EVOH and the -NCO end groups of polyurethane under the action of triethylenediamine inhibits the formation of weak interfaces, thereby suppressing the formation of pores and hydrogen permeation channels and improving hydrogen barrier performance and mechanical properties. Simultaneously, the reaction between the hydroxyl groups of EVOH and the -NCO end groups of polyurethane competes with the repair reaction of free -NCO and water in the repair agent, making the repair rate more controllable and the repair integrity higher. A higher proportion of microcapsules can lead to the formation of more pores and even hydrogen permeation channels in the coating in the initial state, especially during repair release, causing the coating to lose its hydrogen barrier function. The humidity-responsive self-healing microcapsules of this invention have good interfacial compatibility and can form a dense, continuous repair layer after triggering repair.

[0023] The mass ratio of polyetheretherketone (PEEK) powder to ethylene-vinyl alcohol (EVA) copolymer and humidity-responsive self-healing microcapsules is crucial for the hydrogen barrier capacity and self-healing performance of the coating. When the amount of PEEK powder added is too low, the barrier performance of the EVA copolymer decreases under certain humidity conditions, and the insufficient PEEK leads to discontinuous shielding performance in the coating. When the amount of PEEK powder added is too high, the microcapsules are encapsulated by PEEK, restricting the release of the repair agent. Pores also form between the PEEK powder and the EVA copolymer, reducing the hydrogen barrier capacity of the coating.

[0024] In step a, the molar ratio of the hydroxyl groups of the polyol to the -NCO groups of the isocyanate is 1:(1.8~2.8). During mixing, the molar ratio of the residual -NCO groups of the isocyanate in the oil phase to the hydroxyl groups of the polyol in the aqueous phase in step b is 1:(0.2~0.4). The microcapsule core of this invention has a significantly higher degree of cross-linking than the shell, which is beneficial for interfacial bonding with EVOH and improves the interfacial bonding ability with EVOH and polyetheretherketone. The polyurethane and siloxane hybrid shell allows water to pass through EVOH to the shell, and the water stays in the shell for a longer time, thus making the reaction rate of water and the repair agent more controllable and the repair more complete.

[0025] The microcapsules of this invention contain a certain amount of free -NCO groups. When the content of free -NCO groups in the microcapsules decreases to a certain extent, it has little impact on the repair reaction between free -NCO groups and water in the repair agent, because the repair reaction between free -NCO and water is more likely to occur. However, it reduces the covalent bonding between the hydroxyl groups of EVOH and the -NCO end groups of polyurethane during repair, especially after multiple repairs, which significantly reduces the covalent bonding between the hydroxyl groups of EVOH and the -NCO end groups of polyurethane, thereby increasing defects at the repair sites and significantly affecting the hydrogen barrier performance after multiple repairs. When the content of free -NCO groups in the microcapsules exceeds the range specified in this invention, on the one hand, it causes excessive cross-linking of the shell, making it difficult for water molecules to contact the free -NCO in the core through the shell, thus making it difficult to trigger the release of the repair agent from the microcapsule; on the other hand, the residual -NCO in the polyurethane at the repair sites continues to react with moisture in the air to generate carbon dioxide gas, which will lead to a decrease in the airtightness of the repair sites.

[0026] In this invention, the polyether ether ketone powder in S02 has a particle size of 10-30 μm; the compound dispersant is prepared by polyvinylpyrrolidone and Pluronic F127 (polyoxyethylene polyoxypropylene ether) at a mass ratio of 1: (0.6~0.8).

[0027] In this invention, the microcapsule particle size is 5-10 μm. If the particle size is too small, the coating cannot respond to repair, especially in micron-level cracks where it is difficult to effectively release the repair agent. If the particle size is too large, it will easily damage the film-forming continuity and structural integrity of the composite coating of microcapsules, polyether ether ketone and EVOH, which is not conducive to the formation of a dense coating.

[0028] In this invention, the SO2 heat treatment temperature and time are as follows: after drying, heat treatment is performed at 130~160℃ for 10~30 minutes. If the temperature is too low, the coating will be difficult to cure completely; at 160~170℃, the impact is relatively small, the surface will yellow, and the coating may crack; above 180℃, the barrier properties and mechanical properties will decrease; above 200℃, the coating will degrade significantly and crack. Controlling the heat treatment time prevents the polyurethane prepolymer repair agent from curing under heat.

[0029] Free NCO in the oil phase polymerizes with polyols in the aqueous phase to form a polyurethane shell, while tetraethyl orthosilicate hydrolyzes and polymerizes to form a polyurethane / siloxane hybrid shell. The technical challenge lies in preventing all isocyanate groups in the oil phase from reacting with water prematurely. The relative amounts of tetraethyl orthosilicate and isocyanate are also important, as the appropriate degree of cross-linking of the shell is crucial for the normal passage of water molecules when tetraethyl orthosilicate polymerizes under the action of free NCO to form the hybrid shell. This invention designs a polyurethane / siloxane hybrid shell, where the siloxane segments provide sufficient flexibility to prevent premature breakage during transportation and coating, while moisture can contact the core through the polyurethane segments to trigger self-healing.

[0030] This invention designs highly cross-linked polyurethane as a repair agent. After humidity-triggered repair, the urethane groups of the polyurethane in the repair area form hydrogen bonds with the hydroxyl groups of EVOH, promoting the rapid closure of microcracks. The highly cross-linked structure improves the mechanical stability and gas barrier capacity of the repair area, while inhibiting the continuous reaction of residual -NCO in the polyurethane at the repair site with moisture in the air to generate carbon dioxide gas, which would reduce the airtightness (because the ability of highly cross-linked polyurethane to receive water transferred by EVOH decreases).

[0031] The polyol is a mixture of linear diol and branched triol in a molar ratio of 1:(3~5). The polyol is one or more linear diols such as polypropylene glycol, polycaprolactone diol, and polycarbonate diol, combined with one or more branched triols such as glycerol, trimethylolpropane, and trimethylolethane.

[0032] The isocyanate includes one or more of hexamethylene diisocyanate, isophorone diisocyanate, toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, and isophthalic diisocyanate; the silane coupling agent is one of APTES (3-aminopropyltriethoxysilane), GPTMS ((3-glycidyloxypropyl)trimethoxysilane), MPTMS ((3-mercaptopropyl)trimethoxysilane), KH560 (γ-glycidyl etheroxypropyltrimethoxysilane), and KH792 (γ-aminoethylaminopropyltrimethoxysilane).

[0033] Preferably, the strong shear stirring rate is 6000~10000 rpm.

[0034] Compared with the prior art, the beneficial effects of this invention are:

[0035] 1. This invention provides a self-healing hydrogen barrier composite coating for hydrogen storage or transportation devices, achieving active sealing and long-term barrier against hydrogen permeation pathways in complex environments. A multifunctional hydrogen barrier network is constructed through the synergistic interaction of a highly polar matrix material, a mechanically reinforced polymer, and a microstructure intelligent repair system. By controlling the material ratio and interface structure, efficient response and in-situ curing repair under humidity triggering are achieved.

[0036] 2. This invention provides a self-healing hydrogen barrier composite coating based on humidity-responsive microcapsules. The coating primarily uses ethylene-vinyl alcohol copolymer (EVOH) and polyether ether ketone (PEEK) as structural materials. EVOH possesses good hydrophilicity and undergoes controllable swelling upon moisture absorption, providing a crucial physical pathway for triggering the self-healing process. However, considering the defect of EVOH leading to increased inter-segment gaps and deteriorated barrier performance due to moisture absorption under certain humidity conditions, PEEK is used as a reinforcing phase to provide dimensional stability. This effectively avoids the decrease in hydrogen barrier capacity and deformation caused by the moisture absorption and expansion of EVOH, maintaining the coating's hydrogen barrier shape retention capability under humidity conditions.

[0037] 3. This invention introduces a humidity-responsive self-healing microcapsule system. The microcapsule consists of a polyurethane / siloxane hybrid layer encapsulating a core containing an active repair agent, exhibiting a shell structure highly sensitive to humidity. When ambient humidity increases, water molecules first accumulate at microcracks and defect locations. Based on capillary action and polar attraction, water vapor preferentially diffuses to the defect tip region, and stress propagation at the crack triggers the rupture of the microcapsules embedded in the coating. The ruptured microcapsules release the core repair agent (such as isocyanate, polyol, or silane coupling agent) which undergoes a moisture-curing reaction, filling and sealing the crack channels in situ, thereby achieving targeted defect repair and rapid restoration of the hydrogen barrier function.

[0038] 4. The self-healing system has the following outstanding technical advantages and implementation difficulties: (1) It is necessary to accurately control the compatibility and micro-distribution of EVOH / PEEK to ensure that the micro-phase interface forms a gas diffusion barrier zone; (2) It is necessary to achieve the coupling and matching of humidity response regulation of microcapsule wall and water vapor enrichment in cracks; (3) The cross-linking activity, fluidity and curing path of the repair agent in the microcrack channel must be precisely matched with the internal stress distribution of the material, otherwise the airtightness of the repair area cannot be guaranteed.

[0039] 5. The humidity-responsive self-healing intelligent barrier system constructed from a humidity-responsive microcapsule-based self-healing hydrogen barrier composite coating of the present invention has significant advantages in various scenarios, specifically including:

[0040] (1) Long-term service environment of hydrogen pipelines: Under high-velocity gas erosion conditions, microcracks are easily generated on the coating surface. This invention can actively repair micro-damage by inducing microcapsule rupture and rapid solidification through humidity, thereby closing the cracks and ensuring the long-term stable operation of the pipeline.

[0041] (2) Static aging issues of stationary hydrogen storage equipment: Under long-term storage conditions, changes in temperature and humidity may cause aging of material interfaces or damage to microstructures. Self-healing mechanisms can effectively delay aging, maintain material density, and reduce maintenance frequency and operational risks.

[0042] (3) Dynamic high-speed equipment such as hydrogen fuel cell vehicles: During frequent start-stop and high-speed operation, impact loads may cause damage to the microstructure of the sealing layer. The self-healing coating can automatically seal the microcracks formed in response to humidity changes, improve the system's sealing performance and impact resistance, and enhance equipment safety.

[0043] 6. The humidity response mechanism of this invention has intelligent adjustment characteristics, meaning that repair is only triggered when the coating is damaged and accompanied by humidity intrusion, avoiding excessive release of repair agent or structural disturbance. This intelligent self-healing process can promptly block hydrogen leakage paths, and the reinforcing effect of polyetheretherketone powder can also delay the coating aging process, thereby effectively improving the system's service life and operational safety. Attached Figure Description

[0044] Figure 1 This is a diagram showing the repair efficiency of the self-healing hydrogen barrier composite coating for hydrogen storage or transportation devices in Example 1 after repeated damage-repair cycles.

[0045] Figure 2 These are the infrared spectra of the hydrogen barrier composite coatings for hydrogen storage or transportation devices of Example 1 and Comparative Example 1.

[0046] Figure 3 This is a humidity-responsive microcapsule SEM image of the self-healing hydrogen barrier composite coating for hydrogen storage or transportation devices in Example 1.

[0047] Figure 4 This is a surface SEM image of the self-healing hydrogen barrier composite coating for hydrogen storage or transportation devices in Example 1.

[0048] Figure 5 The surface SEM image of the self-healing hydrogen barrier composite coating used in hydrogen storage or transportation devices in Comparative Example 4 is shown.

[0049] Figure 6 The image shows a surface SEM image of the self-healing hydrogen barrier composite coating used in hydrogen storage or transportation devices, as shown in Comparative Example 5. Detailed Implementation

[0050] To make the objectives and technical advantages of the present invention clearer, the above-mentioned contents of the present invention are further described in detail below by way of embodiments. However, these should not be regarded as all embodiments of the above-mentioned contents of the present invention. All other embodiments obtained by those skilled in the art before creative labor are still within the protection scope of the present invention.

[0051] Unless otherwise specified, wt% refers to the mass fraction of a substance relative to the solvent when it is added.

[0052] Example 1

[0053] 1) The surface of the stainless steel pipe substrate is sandblasted and pickled to remove oxide scale and impurities;

[0054] 2) Mix polyimide emulsion with a solid content of 30wt%, polyvinyl alcohol (Mw=30000), γ-glycidyl etheroxypropyltrimethoxysilane and deionized water in a mass ratio of 1:0.05:0.02:4, and apply the mixture to the inner wall of the steel pipe substrate. After drying, cure at 160℃ to obtain a steel pipe substrate with a base coating.

[0055] 3) At 70℃, 9wt% ethylene-vinyl alcohol copolymer particles (source: Aladdin P485585) were added to a mixed solvent of ethanol and water (volume ratio 3:7) and stirred thoroughly to form a transparent solution. Polyetheretherketone powder, humidity-responsive self-healing microcapsules, and a compound dispersant were ultrasonically dispersed into the ethylene-vinyl alcohol copolymer solution. The mass ratio of ethylene-vinyl alcohol copolymer, polyetheretherketone powder, humidity-responsive self-healing microcapsules, and compound dispersant was 1:0.4:0.24:0.05. 0.5wt% silane coupling agent APTES was added dropwise while stirring at 50 rpm. The mixed coating solution was then applied to the inner wall of a steel pipe substrate with a base coating. After drying, it was heat-treated at 150℃ for 20 min to finally form a humidity-responsive self-healing hydrogen barrier coating. The compound dispersant was prepared by mixing polyvinylpyrrolidone and Pluronic F127 at a mass ratio of 1:0.6.

[0056] The preparation process of the humidity-responsive self-healing microcapsules is as follows:

[0057] Step a) In a nitrogen atmosphere at 30°C, 25 wt% of polyol (composed of polypropylene glycol and glycerol in a molar ratio of 1:4), isophorone diisocyanate in proportion to the polyol, and then 0.25 wt% triethylenediamine are added. The mixture is stirred at 50 rpm for 3 h to obtain a polyurethane prepolymer. The polyurethane prepolymer is dissolved in 4 times its mass of ethyl acetate, and 0.8 wt% of silane coupling agent APTES is added. The mixture is then thoroughly mixed to obtain an oil phase. The isophorone diisocyanate to polyol ratio refers to the molar ratio of the hydroxyl groups of the polyol to the -NCO groups of the isocyanate in step a being 1:2.3.

[0058] Step b) Dissolve 1.8 wt% polyvinyl alcohol in deionized water, and simultaneously add 8 wt% polyol (composed of polypropylene glycol and glycerol in a molar ratio of 1:1) and 10 wt% tetraethyl orthosilicate. Adjust the pH of the aqueous phase to 5 using 9.5 g / ml dilute hydrochloric acid. Under strong shear stirring at 9000 rpm, slowly add the oil phase obtained in step a) dropwise to the aqueous phase and stir until a uniform emulsion is formed. During mixing, the molar ratio of the residual -NCO groups of isocyanate in the oil phase to the hydroxyl groups of the polyol in the aqueous phase in step b is 1:0.3. After stirring at 60 °C for 6 h, the system is cooled to room temperature, washed 6 times alternately with deionized water and ethanol, centrifuged, and vacuum dried to obtain stable microcapsules.

[0059] As a verification experiment of coating performance, the coating was applied to a stainless steel substrate. After curing, a 5N normal pressure was applied to the substrate to create microcracks. After removing the load, a static self-healing process was carried out for 8 hours in an environment of 25℃, 1 atm, and 70% relative humidity. This process was repeated six times. After each repair, the hydrogen permeability was measured, and the repair efficiency was calculated. Repair efficiency (%) = (Hydrogen permeability after coating damage in the example - Hydrogen permeability after self-healing of the coating in the example) / (Hydrogen permeability after coating damage in the example - Initial hydrogen permeability of the coating in the example) × 100%. The repair efficiency of the comparative example was calculated using the same formula.

[0060] Figure 1 The diagram shows the repair efficiency of Example 1 after repeated damage-repair cycles, illustrating that the coating still maintains a high self-healing ability (>90%) after 6 damage-repair cycles.

[0061] Figure 2 The infrared spectrum of the coating prepared in Example 1 is shown. FTIR analysis was used to determine the functional groups and molecular structures of each component in the self-healing hydrogen barrier composite coating before and after the addition of microcapsules. Comparing the two spectra, it can be observed that the two coatings are at 3413.52 cm⁻¹. -1 The presence of broad OH stretching vibration peaks at both locations indicates that the hydroxyl groups on the ethylene-vinyl alcohol copolymer backbone of the coating exhibit intermolecular hydrogen bonds with other components. Both coatings show a peak at 1594.97 cm⁻¹. -1 The nearby benzene ring skeletal vibration peak is at 833.71 cm⁻¹. -1 The absorption peak at the para-substituted benzene ring indicates the presence of a para-substituted benzene ring structure in both coatings, and the asymmetric stretching vibration of the COC bond (141.50 cm⁻¹) is also observed. -1 The peak at 1653.70 cm⁻¹ is a characteristic absorption peak for polyetheretherketone (PEEK). The amide I band of polyurethane exhibits C=O stretching vibration (1653.70 cm⁻¹). -1 The wavenumber shifts to lower wavenumbers due to hydrogen bonding. The coating with added microcapsules showed a wavenumber shift at 3413.52 cm⁻¹. -1The broadening of the OH absorption peak is likely due to the superposition of the NH stretching vibration and the OH stretching vibration of polyurethane. The symmetric stretching vibration of the Si-O-Si bond (1094.51 cm⁻¹) -1 ) and bending vibration (673.94 cm) -1 This confirmed the formation of a polyurethane / siloxane hybrid structure in the microcapsule shell. The coating containing the microcapsules was observed at 2024.93 cm⁻¹. -1 The N=C=O asymmetric stretching vibration peak at the point indicates that the polyurethane prepolymer in the microcapsule contains free N=C=O.

[0062] Figure 3 The image shows a SEM image of the microcapsules prepared in Example 1, illustrating that the humidity-responsive microcapsules prepared by this method have a rough surface and a particle size of approximately 10 μm. The rough surface is due to the attachment of small-sized (0.5~1 μm) microcapsules to the surface of larger-sized microcapsules. This structure increases the contact area with the ethylene-vinyl alcohol copolymer matrix and improves the interfacial bonding ability.

[0063] Figure 4 The surface SEM image of the coating prepared in Example 1 shows that the coating prepared by this method has a dense surface and hydrogen barrier capability.

[0064] Example 2

[0065] 1) The surface of the stainless steel pipe substrate is sandblasted and pickled to remove oxide scale and impurities;

[0066] 2) Mix polyimide emulsion with a solid content of 40wt%, polyvinyl alcohol (Mw=30000), γ-glycidyl etheroxypropyltrimethoxysilane and deionized water in a mass ratio of 1:0.04:0.03:4, and apply the mixture to the inner wall of the steel pipe substrate. After drying, cure at 160℃ to obtain a steel pipe substrate with a base coating.

[0067] 3) At 70℃, 12wt% ethylene-vinyl alcohol copolymer was added to a mixed solvent of ethanol and water (volume ratio 3:7) and stirred thoroughly to form a transparent solution. Polyetheretherketone powder, humidity-responsive self-healing microcapsules, and a compound dispersant were ultrasonically dispersed into the ethylene-vinyl alcohol copolymer solution. The mass ratio of ethylene-vinyl alcohol copolymer, polyetheretherketone powder, humidity-responsive self-healing microcapsules, and compound dispersant was 1:0.6:0.28:0.03. 0.5wt% silane coupling agent APTES was added dropwise while stirring at 50 rpm. The mixed coating solution was then applied to the inner wall of a steel pipe substrate with a base coating. After drying, it was heat-treated at 140℃ for 25 min to finally form a humidity-responsive self-healing hydrogen barrier coating. The compound dispersant was prepared by mixing polyvinylpyrrolidone and Pluronic F127 at a mass ratio of 1:0.7.

[0068] The preparation process of the humidity-responsive self-healing microcapsules is as follows:

[0069] Step a) In a nitrogen atmosphere at 28°C, 18 wt% of a polyol (composed of polycarbonate diol and trimethylolpropane in a molar ratio of 1:3), hexamethylene diisocyanate in proportion to the polyol, and then 0.25 wt% of triethylenediamine were added. The mixture was stirred at 50 rpm for 3 h to obtain a polyurethane prepolymer. The polyurethane prepolymer was dissolved in 4 times its mass of ethyl acetate, and 0.8 wt% of silane coupling agent APTES was added. The mixture was stirred evenly to obtain an oil phase. In step a), the molar ratio of the hydroxyl groups of the polyol to the -NCO groups of the isocyanate was 1:2.3.

[0070] Step b) Dissolve 2 wt% polyvinyl alcohol in deionized water, and simultaneously add 6 wt% polyol (composed of polycarbonate diol and trimethylolpropane in a molar ratio of 1:1) and 12 wt% tetraethyl orthosilicate. Adjust the pH of the aqueous phase to 4.5 using 9.5 g / ml dilute hydrochloric acid. Under strong shear stirring at 8000 rpm, slowly add the oil phase obtained in step a) dropwise to the aqueous phase and stir until a uniform emulsion is formed. During mixing, the molar ratio of the residual -NCO groups of isocyanate in the oil phase to the hydroxyl groups of the polyol in the aqueous phase in step b is 1:0.3. After stirring at 40°C for 5 h, the system is cooled to room temperature, washed 6 times alternately with deionized water and ethanol, centrifuged, and vacuum dried to obtain stable microcapsules.

[0071] Example 3

[0072] 1) The surface of the stainless steel pipe substrate is sandblasted and pickled to remove oxide scale and impurities;

[0073] 2) Mix polyimide emulsion with a solid content of 30wt%, polyvinyl alcohol (Mw=30000), γ-aminoethylaminopropyltrimethoxysilane and deionized water evenly at a mass ratio of 1:0.07:0.02:4, and then dip-coat the inner wall of the steel pipe substrate; after drying, cure at 160℃ to obtain a steel pipe substrate with a base coating.

[0074] 3) At 70℃, 10.5wt% ethylene-vinyl alcohol copolymer was added to a mixed solvent of ethanol and water (volume ratio 3:7) and stirred thoroughly to form a transparent solution. Polyetheretherketone powder, humidity-responsive self-healing microcapsules, and a compound dispersant were ultrasonically dispersed into the ethylene-vinyl alcohol copolymer solution. The mass ratio of ethylene-vinyl alcohol copolymer, polyetheretherketone powder, humidity-responsive self-healing microcapsules, and compound dispersant was 1:0.45:0.26:0.04. 0.8wt% silane coupling agent GPTMS was added dropwise while stirring at 50 rpm. The mixed coating solution was then applied to the inner wall of a steel pipe substrate with a base coating. After drying, it was heat-treated at 150℃ for 20 min to finally form a humidity-responsive self-healing hydrogen barrier coating. The compound dispersant was prepared by mixing polyvinylpyrrolidone and Pluronic F127 at a mass ratio of 1:0.8.

[0075] The preparation process of the humidity-responsive self-healing microcapsules is as follows:

[0076] Step a) In a nitrogen atmosphere at 35°C, 20 wt% of a polyol (composed of polyethylene glycol and trimethylolethane in a molar ratio of 1:5) and an isocyanate in proportion to the polyol (composed of hexamethylene diisocyanate and isophorone diisocyanate in a mass ratio of 1:1) were added to dichloromethane, followed by the addition of 0.3 wt% triethylenediamine. The mixture was stirred at 50 rpm for 3 h to obtain a polyurethane prepolymer. The polyurethane prepolymer was dissolved in 4 times its mass of ethyl acetate, and 1.0 wt% of the silane coupling agent GPTMS was added. The mixture was stirred until homogeneous to obtain an oil phase. In step a), the molar ratio of the hydroxyl groups of the polyol to the -NCO groups of the isocyanate was 1:1.8.

[0077] Step b) Dissolve 1.5 wt% polyvinyl alcohol in deionized water, and simultaneously add 10 wt% polyol (composed of polyethylene glycol and trimethylolethane in a molar ratio of 1:1) and 15 wt% tetraethyl orthosilicate. Adjust the pH of the aqueous phase to 4 using 9.5 g / ml dilute hydrochloric acid. Under strong shear stirring at 8000 rpm, slowly add the oil phase obtained in step a) dropwise to the aqueous phase and stir until a uniform emulsion is formed. During mixing, the molar ratio of the residual -NCO groups of isocyanate in the oil phase to the hydroxyl groups of the polyol in the aqueous phase in step b is 1:0.3. After stirring at 50 °C for 5 h, the system is cooled to room temperature, washed 6 times alternately with deionized water and ethanol, centrifuged, and vacuum dried to obtain stable microcapsules.

[0078] Example 4

[0079] 1) The surface of the stainless steel pipe substrate is sandblasted and pickled to remove oxide scale and impurities;

[0080] 2) Mix polyimide emulsion with a solid content of 40wt%, polyvinyl alcohol (Mw=30000), 3-aminopropyltriethoxysilane and deionized water evenly at a mass ratio of 1:0.06:0.025:4, and then dip the mixture into the inner wall of the steel pipe substrate; after drying, cure at 160℃ to obtain a steel pipe substrate with a base coating.

[0081] 3) At 70℃, 9.8wt% ethylene-vinyl alcohol copolymer was added to a mixed solvent of ethanol and water (volume ratio 3:7) and stirred thoroughly to form a transparent solution. Polyetheretherketone powder, humidity-responsive self-healing microcapsules, and a compound dispersant were ultrasonically dispersed into the ethylene-vinyl alcohol copolymer solution. The mass ratio of ethylene-vinyl alcohol copolymer, polyetheretherketone powder, humidity-responsive self-healing microcapsules, and compound dispersant was 1:0.42:0.25:0.03. 0.7wt% silane coupling agent GPTMS was added dropwise while stirring at 50 rpm. The mixed coating solution was then applied to the inner wall of a steel pipe substrate with a base coating. After drying, it was heat-treated at 150℃ for 25 min to finally form a humidity-responsive self-healing hydrogen barrier coating. The compound dispersant was prepared by mixing polyvinylpyrrolidone and Pluronic F127 at a mass ratio of 1:0.6.

[0082] The preparation process of the humidity-responsive self-healing microcapsules is as follows:

[0083] Step a) In a nitrogen atmosphere at 32°C, 15 wt% of a polyol (composed of polycaprolactone diol and glycerol in a molar ratio of 1:3) and an isocyanate in proportion to the polyol (composed of hexamethylene diisocyanate and isophorone diisocyanate in a mass ratio of 1:1) were added to dichloromethane, followed by the addition of 0.25 wt% triethylenediamine. The mixture was stirred at 50 rpm for 3 h to obtain a polyurethane prepolymer. The polyurethane prepolymer was dissolved in 4 times its mass of ethyl acetate, and 0.8 wt% of a silane coupling agent GPTMS was added. The mixture was stirred until homogeneous to obtain an oil phase. In step a), the molar ratio of the hydroxyl groups of the polyol to the -NCO groups of the isocyanate was 1:2.

[0084] Step b) Dissolve 1.8 wt% polyvinyl alcohol in deionized water, and simultaneously add 8% polyol (composed of polycaprolactone diol and glycerol in a molar ratio of 1:1) and 10 wt% tetraethyl orthosilicate. Adjust the pH of the aqueous phase to 5 using 9.5 g / ml dilute hydrochloric acid. Under strong shear stirring at 9000 rpm, slowly add the oil phase obtained in step a) dropwise to the aqueous phase and stir until a uniform emulsion is formed. During mixing, the molar ratio of the residual -NCO groups of isocyanate in the oil phase to the hydroxyl groups of the polyol in the aqueous phase in step b is 1:0.4. After stirring at 60 °C for 5 h, the system is cooled to room temperature, washed 6 times alternately with deionized water and ethanol, centrifuged, and vacuum dried to obtain stable microcapsules.

[0085] Example 5

[0086] 1) The surface of the stainless steel pipe substrate is sandblasted and pickled to remove oxide scale and impurities;

[0087] 2) Mix polyimide emulsion with a solid content of 40wt%, polyvinyl alcohol (Mw=30000), γ-glycidyl etheroxypropyltrimethoxysilane and deionized water evenly at a mass ratio of 1:0.07:0.02:4, and dip-coat the inner wall of the steel pipe substrate; after drying, cure at 160℃ to obtain a steel pipe substrate with a base coating.

[0088] 3) At 70℃, 11.4wt% of ethylene-vinyl alcohol copolymer was added to a mixed solvent of ethanol and water (volume ratio 3:7) and stirred thoroughly to form a transparent solution. Polyetheretherketone powder, humidity-responsive self-healing microcapsules, and a compound dispersant were ultrasonically dispersed into the ethylene-vinyl alcohol copolymer solution. The mass ratio of ethylene-vinyl alcohol copolymer, polyetheretherketone powder, humidity-responsive self-healing microcapsules, and compound dispersant was 1:0.54:0.25:0.047. 1.2wt% of silane coupling agent GPTMS was added dropwise while stirring at 50 rpm. The mixed coating solution was then applied to the inner wall of a steel pipe substrate with a base coating. After drying, it was heat-treated at 160℃ for 20 min to finally form a humidity-responsive self-healing hydrogen barrier coating. The compound dispersant was prepared by mixing polyvinylpyrrolidone and Pluronic F127 at a mass ratio of 1:0.6.

[0089] The preparation process of the humidity-responsive self-healing microcapsules is as follows:

[0090] Step a) In a nitrogen atmosphere at 29°C, 20 wt% of a polyol (composed of polycaprolactone diol and trimethylolpropane in a molar ratio of 1:4) and an isocyanate in proportion to the polyol (composed of hexamethylene diisocyanate and isophorone diisocyanate in a mass ratio of 1:1) were added to dichloromethane, followed by the addition of 0.25 wt% triethylenediamine. The mixture was stirred at 50 rpm for 3 h to obtain a polyurethane prepolymer. The polyurethane prepolymer was dissolved in 4 times its mass of ethyl acetate, and 0.8 wt% of the silane coupling agent GPTMS was added. The mixture was stirred until homogeneous to obtain an oil phase. In step a), the molar ratio of the hydroxyl groups of the polyol to the -NCO groups of the isocyanate was 1:2.3.

[0091] Step b) Dissolve 1.7 wt% polyvinyl alcohol in deionized water, and simultaneously add 6 wt% polyol (composed of polycaprolactone diol and trimethylolpropane in a molar ratio of 1:1) and 10 wt% tetraethyl orthosilicate. Adjust the pH of the aqueous phase to 4.5 using 9.5 g / ml dilute hydrochloric acid. Under strong shear stirring at 8000 rpm, slowly add the oil phase obtained in step a) dropwise to the aqueous phase and stir until a uniform emulsion is formed. During mixing, the molar ratio of the residual -NCO groups of isocyanate in the oil phase to the hydroxyl groups of the polyol in the aqueous phase in step b is 1:0.2. After stirring at 50 °C for 8 h, the system is cooled to room temperature, washed 6 times alternately with deionized water and ethanol, centrifuged, and vacuum dried to obtain stable microcapsules.

[0092] Comparative Example 1 (without humidity-responsive microcapsules)

[0093] The only difference between this comparative example and Example 1 is that humidity-responsive microcapsules were not added.

[0094] Comparative Example 2 (without added compound dispersant)

[0095] The only difference between this comparative example and Example 1 is that no compound dispersant was added when preparing the hydrogen barrier functional layer.

[0096] Comparative Example 3 (Controlling the composition of the microcapsule core)

[0097] The difference between this comparative example and Example 1 is that the core is controlled to be free of free NCO (specifically, the molar ratio of the hydroxyl group of the polyol to the -NCO group of the isocyanate in step a is 1.65: 2.3; the molar ratio of the hydroxyl group of the polyol in step a to the hydroxyl group of the polyol in step b is kept consistent with Example 1).

[0098] Comparative Example 4 (Changing the dosage of microcapsules)

[0099] The only difference between this comparative example and Example 1 is that the amount of microcapsules used is 0.4 times the mass of the ethylene-vinyl alcohol copolymer.

[0100] Comparative Example 5 (changing the amount of polyetheretherketone)

[0101] The only difference between this comparative example and Example 1 is that the amount of polyetheretherketone used is 0.7 times the mass of the ethylene-vinyl alcohol copolymer.

[0102] Comparative Example 6 (changing the degree of crosslinking in step a)

[0103] The only difference between this comparative example and Example 1 is that in step a, the polyol is composed of polypropylene glycol and glycerol in a molar ratio of 3:2.

[0104] Comparative Example 7 (microcapsule particle size controlled >10μm)

[0105] The only difference between this comparative example and Example 1 is that the high-shear stirring speed was adjusted to 3000 rpm to control the microcapsule particle size to >10 μm.

[0106] Comparative Example 8 (changing the amount of triethylenediamine added)

[0107] The only difference between this comparative example and Example 1 is that the amount of triethylenediamine added is 1.3 wt%.

[0108] Comparative Example 9 (using polyimide)

[0109] The only difference between this comparative example and Example 1 is that in step 3), EVOH is replaced with polyimide (PI), and the mixed solvent of ethanol and water (volume ratio 3:7) is replaced with chloroform.

[0110] The initial hydrogen permeability, the hydrogen permeability after the first self-healing, and the repair efficiency were measured under the conditions of 25℃, 1 atm, and 70% relative humidity. The specific measurement process was the same as in Example 1.

[0111] Table 1 Performance Data Sheet (25℃, 1 atm, 70% relative humidity)

[0112]

[0113] Compared to Example 1, which did not include humidity-responsive microcapsules, Comparative Example 1 showed that its initial hydrogen permeability was essentially the same as that of Example 1, indicating that the humidity-responsive microcapsules did not affect the initial hydrogen barrier function. Without the addition of humidity-responsive microcapsules, it had no self-repairing effect.

[0114] Compared to Example 1, Comparative Example 2 did not include a compound dispersant, which affected the uniform dispersion of microcapsules, ethylene-vinyl alcohol copolymer and polyether ether ketone, resulting in reduced repair efficiency and increased hydrogen permeability after self-repair.

[0115] Compared to Example 1, Comparative Example 3 showed that the core of the control bag did not contain free NCO, resulting in reduced repair efficiency and a significant increase in hydrogen permeability after self-repair.

[0116] Comparative Example 4, by changing the relative amount of microcapsules compared to Example 1, resulted in the microcapsules forming pores in the coating, creating hydrogen permeation channels. This significantly reduced the coating's hydrogen barrier function and led to poor repair results. Figure 5 As shown, the microcapsules form more pores in the coating in the initial state, especially during repair release.

[0117] Compared to Example 1, Comparative Example 5, with its increased relative amount of polyetheretherketone (PEEK), showed significantly inferior hydrogen barrier function and repair effect compared to Example 1. This demonstrates that the relative amounts of microcapsules and PEEK have a crucial impact on material properties. Figure 6As shown, the microcapsules are encapsulated in polyetheretherketone (PEEK), which restricts the release of the repair agent. Pores are formed between the PEEK powder and the ethylene-vinyl alcohol copolymer, thus reducing the hydrogen barrier and repair capabilities of the coating.

[0118] Compared to Example 1, Comparative Example 6 reduced the crosslinking degree of the microcapsule polyurethane prepolymer repair agent. The repair agent had a lower crosslinking degree, resulting in excessively high free volume of the polyurethane chains at the repair sites, and the coating lost its barrier effect against hydrogen.

[0119] Compared to Example 1, Comparative Example 7 controlled the microcapsule particle size to be >10 μm. The larger microcapsule particle size made it difficult to form a continuous and dense coating, thus affecting the initial hydrogen barrier function of the coating.

[0120] Compared with Example 1, Comparative Example 8 changed the amount of triethylenediamine, resulting in low repair integrity and poor coating density.

[0121] Compared to Example 1, Comparative Example 9 used polyimide instead of ethylene-vinyl alcohol copolymer. The coating had normal hydrogen barrier function, but the bonding between the repair agent and the polyimide matrix was not strong after curing, and the hydrogen barrier ability after repair was significantly lower than that of Example 1.

[0122] The materials used in embodiments of the present invention are suitable not only for self-healing under high humidity conditions but also for coating self-healing under moderate humidity conditions (e.g., 50% relative humidity), thus reducing the humidity threshold requirement for repair. For example, in Example 1, under 50% relative humidity (other test conditions as described above), the hydrogen permeability after self-healing was 372.31 cm⁻¹. 3 / m 2 • 24h • 0.1MPa, the repair efficiency is 95.40%.

[0123] Although the invention has been described with reference to a limited number of embodiments, those skilled in the art will understand from the foregoing description that other embodiments are conceivable within the scope of the invention described herein. Furthermore, it should be noted that the language used in this specification has been chosen primarily for readability and edibility purposes, and not for the purpose of interpreting or limiting the subject matter of the invention. Therefore, many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the appended claims. The disclosure of the invention is illustrative and not restrictive, and the scope of the invention is defined by the appended claims.

Claims

1. A self-healing hydrogen barrier composite coating for hydrogen storage or transportation devices, characterized in that, It includes a two-layer structure consisting of a self-healing barrier layer and a base layer of humidity-responsive microcapsules, wherein the humidity-responsive microcapsules have a polyurethane prepolymer as the core and polyurethane and siloxane as the hybrid shell. The self-healing hydrogen barrier composite coating is prepared by the following steps: S01, mix polyimide emulsion with a solid content of 25~40wt%, polyvinyl alcohol, coupling agent and deionized water evenly in a mass ratio of 1 : (0.04~0.07) : (0.02~0.03) : 4, dip and coat it on the inner wall of the substrate, dry it and cure it at 160~180℃ to form a base coating on the substrate; In a solvent at 60-80℃, 8-12 wt% ethylene-vinyl alcohol copolymer is added and stirred thoroughly to form a transparent ethylene-vinyl alcohol copolymer solution. Polyetheretherketone powder, humidity-responsive self-healing microcapsules, and a compound dispersant are ultrasonically dispersed into the ethylene-vinyl alcohol copolymer solution. The mass ratio of ethylene-vinyl alcohol copolymer, polyetheretherketone powder, humidity-responsive self-healing microcapsules, and the compound dispersant is 1:(0.4-0.6):(0.22-0.3):(0.03-0.05). The compound dispersant is prepared by mixing polyvinylpyrrolidone and Pluronic F127 at a mass ratio of 1:(0.6-0.8). 0.3-1.5 wt% silane coupling agent is added dropwise under continuous stirring to obtain a mixed coating liquid. The mixed coating liquid is applied to the base coat of the substrate. After drying, it is heat-treated at 130-160℃ for 10-30 minutes to finally form a humidity-responsive microcapsule self-healing barrier layer. The preparation of the humidity-responsive self-healing microcapsules described in S02 includes the following steps: Step a) In a nitrogen atmosphere at 20-40°C, polyol and isocyanate are added to dichloromethane, followed by the addition of 0.05-0.5 wt% triethylenediamine. The mixture is stirred continuously for 0.5-4 h to obtain a polyurethane prepolymer. The polyurethane prepolymer is dissolved in ethyl acetate, and 0.3-1.5 wt% silane coupling agent is added and mixed thoroughly to obtain an oil phase. The molar ratio of the hydroxyl groups of the polyol to the -NCO groups of the isocyanate in step a is 1:(1.8-2.8). Step b) Dissolve 0.5-2.5 wt% polyvinyl alcohol in water, add polyol and 5-20 wt% tetraethyl orthosilicate, and adjust the pH of the aqueous phase to 4-5 using 9-10 g / ml dilute hydrochloric acid; under strong shear stirring, slowly add the oil phase obtained in step a) dropwise to the aqueous phase, stirring until a homogeneous emulsion is formed, ensuring that the molar ratio of the residual -NCO groups of isocyanate in the oil phase to the hydroxyl groups of the polyol in the aqueous phase of step b is 1:(0.2-0.4); after stirring at 40-60℃ for 4-8 h, cool the system to room temperature, wash 5-6 times alternately with deionized water and ethanol, centrifuge, and vacuum dry to obtain stable microcapsules; wherein the microcapsules contain free NCO; The polyol mentioned in step a) is a mixture of linear diol and branched triol in a molar ratio of 1:(3~5); Step b) The strong shear stirring rate is 6000~10000 rpm, and the microcapsule particle size is controlled to be 5~10 μm.

2. The self-healing hydrogen barrier composite coating for hydrogen storage or transportation devices according to claim 1, characterized in that, Before step S01, the substrate is subjected to sandblasting and pickling to remove oxide scale and impurities; the substrate is a stainless steel pipe substrate or a steel hydrogen storage tank.

3. The self-healing hydrogen barrier composite coating for hydrogen storage or transportation devices according to claim 1, characterized in that, The coupling agent described in S01 is one or more of γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-epoxypropyltriethoxysilane, and isopropyltris(dioctylpyrophosphate)titanate.

4. The self-healing hydrogen barrier composite coating for hydrogen storage or transportation devices according to claim 1, characterized in that, The polyether ether ketone powder described in S02 has a particle size of 10-30 μm.

5. The self-healing hydrogen barrier composite coating for hydrogen storage or transportation devices according to claim 1, characterized in that, The linear diol is one or more of polypropylene glycol, polycaprolactone diol, and polycarbonate diol, and the branched triol is one or more of glycerol, trimethylolpropane, and trimethylolethane.

6. The self-healing hydrogen barrier composite coating for hydrogen storage or transportation devices according to claim 1, characterized in that, In step a), the isocyanate includes one or more of hexamethylene diisocyanate, isophorone diisocyanate, toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, and isophthalic diisocyanate; the silane coupling agent is one of APTES, GPTMS, MPTMS, KH560, and KH792.

7. A method for preparing a self-healing hydrogen barrier composite coating for a hydrogen storage or transportation device as described in any one of claims 1 to 6.

8. The application of the self-healing hydrogen barrier composite coating for hydrogen storage or transportation devices as described in any one of claims 1 to 6 in hydrogen energy storage and transportation.

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