Preparation method of laser-induced graphene composite film based on bionic multi-level structure, composite film and application

Abstract

The application provides a preparation method of a laser-induced graphene composite film based on a biomimetic multi-level structure, the composite film and application. It relates to the fields of material surface engineering and deicing technology, and the preparation method comprises the following steps: cleaning and drying pretreatment of a polyimide film substrate; through selective scanning by a pulsed laser, a laser-induced graphene layer is generated in situ on the substrate surface synchronously, and a biomimetic multi-level structure containing a periodic microporous array and a three-dimensional porous graphene network is constructed; the product is immersed in a nano-hydrophobic solution for modification and solidification to form a three-level hydrophobic coating; annealing treatment is performed under inert gas protection to eliminate internal stress, and the composite film is obtained after cooling. The film has super-hydrophobicity, low ice adhesion strength and high efficient light-heat conversion capacity. The application aims to solve the safety and efficiency problems in the fields of aviation, wind power, photovoltaic and the like due to the lack of long-acting, stable, low-energy and function-integrated deicing materials.

Description

Technical Field

[0001] This invention relates to the fields of material surface engineering and de-icing technology, specifically to a method for preparing a synergistic anti-icing and de-icing composite film based on a biomimetic multi-level structure that mimics a bee's honeycomb, a bull horn fish's skin, and a butterfly's wings, as well as the composite film and its applications. Background Technology

[0002] Icing on critical infrastructure such as aviation, wind power, and photovoltaics poses a significant challenge to their safe and stable operation and economic benefits. Icing on aircraft wings / engine inlets drastically alters aerodynamic shape, leading to decreased lift and increased drag, thus posing flight safety risks. Icing on wind turbine blades disrupts their aerodynamic balance, significantly reducing wind capture efficiency and power generation, and in severe cases, may cause unit shutdown or structural damage. Icing on solar photovoltaic modules blocks sunlight, drastically reducing photoelectric conversion efficiency. At the same time, ice loads can cause irreversible damage to module frames and glass substrates, increasing the maintenance costs and safety hazards of photovoltaic power plants.

[0003] Current anti-icing and de-icing solutions for the aforementioned fields all have significant limitations in dealing with their complex and harsh operating conditions. In the aviation industry, to ensure absolute safety, active de-icing systems such as electrothermal and hot gas are widely used, but their continuous high energy consumption fundamentally contradicts the stringent requirements for aircraft weight reduction. In the wind power industry, the blades are huge and often operate in harsh, unattended environments. Existing active de-icing technologies (such as electrothermal films) are energy-intensive and costly, severely impacting the economic benefits of wind farms throughout their entire lifecycle. Traditional physical coatings with hydrophobic properties rapidly degrade or even fail after long-term exposure to ultraviolet radiation, rain erosion, sand and dust abrasion, and extreme temperature cycles, failing to meet the design life requirement of over 20 years. In the photovoltaic industry, existing de-icing methods mostly involve manual ice removal or electric heating. Manual de-icing is inefficient and easily damages the module glass, while electric heating significantly increases the energy consumption of power plant operations, contradicting the energy-saving attributes of photovoltaic power generation.

[0004] The highly efficient photothermal conversion properties of laser-induced graphene (LIG) offer a new approach for low-energy de-icing. However, existing LIG-based technologies are mostly single porous structures with insufficient intrinsic hydrophobicity, and the hydrophobic functional layer and LIG layer are mostly physically bonded, making the interface prone to failure. Furthermore, current technologies do not fully utilize the excellent anti-adhesion and hydrophobic structural characteristics of the biological world, lacking a biomimetic structural design approach to achieve synergistic integration of passive anti-icing and active de-icing, thus failing to address the end-to-end anti-icing and de-icing requirements of "delaying icing, reducing ice adhesion, efficient de-icing, and long-term stability."

[0005] In nature, the hexagonal array structure of a bee's honeycomb possesses excellent structural stability and the ability to control surface contact area; the micron-sized protrusions on the skin of a bullfish can significantly reduce the adhesion of external substances; and the micro-nano striped pit array of butterfly wings has superhydrophobic and anti-adhesion properties. These biological structures provide excellent biomimetic blueprints for the surface topology design of anti-icing materials. Therefore, developing a biomimetic multi-level structure LIG composite film based on bee honeycomb, bullfish skin, and butterfly wings to achieve integrated passive anti-icing and active de-icing has become an urgent need to overcome the bottlenecks in anti-icing and de-icing of high-end equipment such as aviation, wind power, and photovoltaics. Summary of the Invention

[0006] To address the technical challenges of operational safety and economic efficiency in fields such as aviation, wind power, and photovoltaics due to the lack of long-lasting, stable, low-energy-consumption, and integrated anti-icing and de-icing materials, this invention leverages the natural anti-adhesion and hydrophobic structural characteristics of bee honeycombs, horned fish skin, and butterfly wings to provide a synergistic anti-icing and de-icing preparation method, composite film, and applications based on a biomimetic multi-level structure and laser-induced graphene composite film. The core innovations of this invention are: 1. Simplifying the preparation process by simultaneously generating a LIG layer and a biomimetic multi-level micro / nano structure in situ using pulsed laser in a one-step process; 2. Significantly improving interfacial bonding strength and long-term stability by bonding the hydrophobic coating and graphene layer through Si-OC covalent bonds; 3. Constructing a three-level biomimetic structure to achieve integrated synergy between passive anti-icing and active photothermal de-icing, overcoming the shortcomings of existing technologies such as fragmented functions and high energy consumption. This invention is applicable to fields such as aviation, wind power, and photovoltaics that have high requirements for anti-icing performance and environmentally friendly processes. Through structural design, it achieves integrated functions of delaying icing, reducing ice adhesion, and rapid photothermal melting. To achieve the objectives of this invention, the following technical solution is adopted:

[0007] Firstly, a synergistic anti-icing and de-icing preparation method for laser-induced graphene composite films based on biomimetic multi-level structures is proposed, including the following steps:

[0008] S1. Provide a polyimide film substrate and perform surface pretreatment.

[0009] Using homophenylene or biphenyl polyimide film as the substrate, it is ultrasonically cleaned in anhydrous ethanol and deionized water for 5-20 minutes to remove organic contaminants, dust and inorganic salt impurities from the surface. After being dried with high-purity nitrogen, it is dried at 60-80℃ for 10-40 minutes to obtain a smooth and clean substrate surface, which provides a basis for the subsequent construction of biomimetic multi-level structures.

[0010] S2. Pulsed laser selective scanning constructs biomimetic multi-level structures with biomimetic features.

[0011] Selective scanning of the pretreated polyimide film substrate surface was performed using fiber pulsed laser or CO2 pulsed laser (preferably with a wavelength of 1064 nm). Through laser-induced carbonization, a laser-induced graphene layer was simultaneously and in-situ generated on the substrate surface, constructing a biomimetic multi-level structure that respectively carries passive anti-icing and active de-icing functions. By adjusting the scanning path, power, and scanning spacing parameters of the pulsed laser, the array arrangement, unit size, and micromorphology of the first-level biomimetic structure were precisely controlled, matching the natural structural features of a bee's honeycomb, the skin of a bullfish, or the wings of a butterfly.

[0012] (a) Primary structure: a periodic microscopic topological pattern of a regular hexagonal array mimicking a bee honeycomb, a micron-sized protrusion array mimicking a bull-horned fish skin, or a micro-nano pit array mimicking a butterfly wing, with a micron-sized unit feature size of 5-30 μm and an array period of 5-50 μm; among them, the bee honeycomb structure is a regular hexagonal micron-sized pit / protrusion array, which maximizes the reduction of the solid-ice contact area by utilizing the structural stability and spatial arrangement advantages of the regular hexagon; the bull-horned fish skin structure is a near-circular micron-sized protrusion array, which reduces the adhesion between the ice layer and the film surface by relying on the physical barrier effect of the protrusion structure; the butterfly wing structure is a striped micro-nano pit array, which delays the condensation and freezing of water droplets by utilizing the hydrophobic and conductive properties of the striped array; this primary biomimetic structure is a passive anti-icing core layer, which achieves a passive anti-icing function of efficient ice-repellent and anti-ice adhesion by replicating the natural anti-adhesion structure of organisms;

[0013] (b) Secondary structure: A three-dimensional porous graphene network formed on the surface of the primary biomimetic structure and in the exposed area of ​​the substrate, naturally formed by laser-induced carbonization, with a porosity of 60%-85%; This structure is the active ice-melting core layer, which achieves efficient photothermal conversion by relying on high specific surface area and rich pore structure, converting light energy into heat energy to melt the ice layer.

[0014] S3. Preparation of tertiary nanohydrophobic coatings by hydrophobic modification

[0015] The product after S2 treatment is immersed in a nano-hydrophobic layer solution with a concentration of 0.5%-5% v / v for 1-10 minutes to ensure that the solution fully wets the surface of the primary biomimetic structure and the interior of the secondary porous graphene network; the nano-hydrophobic coating solution is a mixed solvent system of isopropanol:ethanol:water = 8:1:1 of fluorinated silanes (preferably heptadecafluorodecyltrimethoxysilane) or perfluoroalkyl silanes.

[0016] After impregnation, remove excess solution and cure at 80-150℃ for 30 min-2 h to allow silane molecules to undergo hydrolysis-condensation reaction with the graphene surface, forming a tertiary nanohydrophobic coating with a thickness of 50-200 nm that is covalently bonded to the graphene layer through Si-OC bonds. This coating, in synergy with the primary biomimetic topology, significantly reduces the surface energy of the film and enhances the passive anti-icing effect.

[0017] S4. Inert gas protective annealing treatment

[0018] The S3-treated material was placed in a tube furnace and annealed under the protection of high-purity argon / nitrogen: the temperature was increased to 200-350℃ at a rate of 2-10℃ / min and held for 30min-2h to eliminate the structural internal stress generated by laser processing and coating curing. Then, it was cooled to room temperature at a rate of ≤5℃ / min. The annealing process further improved the dimensional stability and interfacial bonding strength of the film, ensuring the morphological integrity of the primary biomimetic structure. After cooling, a laser-induced graphene composite film with both passive anti-icing and active de-icing functions was obtained.

[0019] Secondly, a laser-induced graphene composite film based on a biomimetic multi-level structure is provided, the film comprising, from the inside out:

[0020] 1. Polyimide film substrate: It is a homopolymer or biphenyl polyimide, which has excellent high temperature resistance, flexibility and dimensional stability, providing strong mechanical support for the entire composite film and adapting to the characteristics of various application substrates;

[0021] 2. Laser-induced graphene layer: It is generated and bonded in situ with the polyimide substrate without interfacial gaps. It contains a primary periodic micro-topological array that mimics the honeycomb, the skin of a bullfish, and the wings of a butterfly, and a secondary three-dimensional porous graphene network formed on it. The primary biomimetic structure is a passive anti-icing core that replicates the natural anti-sticking and hydrophobic characteristics of biological organisms, while the secondary porous network is an active de-icing core that achieves efficient photothermal conversion.

[0022] 3. Tertiary nano-hydrophobic coating: Si-OC covalent bonded to the surface of laser-induced graphene layer, uniformly attached to the inner pore walls of primary biomimetic structure and secondary porous network, forming a continuous low surface energy interface, which synergistically enhances superhydrophobic and low ice adhesion properties with primary biomimetic structure.

[0023] In conjunction with the second aspect, in the manner achievable in the second aspect, the thin film possesses excellent superhydrophobicity, low ice adhesion strength, and high photothermal conversion capability: the superhydrophobicity is characterized by a water contact angle ≥150° and a roll-off angle ≤10°; the low ice adhesion strength is characterized by an ice adhesion strength ≤20kPa at -15℃; and the photothermal conversion capability is characterized by a photothermal conversion efficiency ≥85% in the 200-2500nm wavelength band. After more than 50 freeze-thaw cycles and Taber abrasion tests, the passive anti-icing and active de-icing performance of the thin film both decrease by ≤5%, demonstrating excellent environmental durability.

[0024] Thirdly, the second aspect is proposed, and in combination with the second aspect, in a manner achievable by the second aspect, the laser-induced graphene composite film is used for anti-icing and de-icing on the leading edge of an aircraft wing, the surface of a wind turbine blade, or a solar photovoltaic module.

[0025] In conjunction with the third aspect, among the feasible methods implemented in the third aspect, a suitable primary biomimetic structure is selected based on the curvature of the substrate, the stress under working conditions, the icing characteristics, and the mechanical requirements of different application substrates:

[0026] Aircraft wing leading edge: The primary structure adopts a regular hexagonal array that resembles a honeycomb, which utilizes its excellent structural stability and resistance to fluid shear to adapt to the high-speed airflow conditions and complex surface curvature of the wing leading edge and withstand the shearing effect of high-speed airflow.

[0027] Wind turbine blades: The primary structure adopts a micron-scale array of protrusions that mimics the skin of a bull horn fish. Relying on its superior anti-adhesion properties, it is suitable for outdoor ultraviolet radiation and rain erosion conditions, reducing the adhesion between ice and the blade. Thin ice can automatically fall off as the blade rotates and vibrates.

[0028] Solar photovoltaic modules: The primary structure adopts a striped pit array that mimics butterfly wings. With its hydrophobic and light-transmitting properties and high light transmittance, it is suitable for flat / micro-curved substrates of photovoltaic modules and long-term outdoor exposure conditions. While achieving de-icing and anti-icing, it reduces the obstruction of sunlight and ensures the photoelectric conversion efficiency of photovoltaic modules.

[0029] By adjusting the pulsed laser scanning path and / or parameters, the selected biomimetic topological array morphology, which mimics a bee's nest, a bull-horned fish's skin, or a butterfly's wing, can be adapted to the surface of the substrate with different curvatures, ensuring the uniformity and stability of the anti-icing and de-icing performance of the film on complex curved and planar substrates.

[0030] The synergistic anti-icing and de-icing principle of this film is as follows: passive anti-icing is the priority, supplemented by active de-icing. In normal low-temperature and humid environments, the film replicates the natural anti-stick and hydrophobic properties of organisms through the synergistic effect of the primary biomimetic topology and the tertiary nano-hydrophobic coating, delaying the condensation and freezing of supercooled water droplets. Even if a thin layer of ice forms, its extremely low adhesion strength allows it to be de-iced by vibrations from equipment operation or natural wind, without the need to initiate active de-icing. When encountering extreme low-temperature environments that form a thicker ice layer, the secondary three-dimensional porous graphene network absorbs the light energy from sunlight or auxiliary light sources, efficiently converting it into heat energy to raise the surface temperature of the film above the freezing point, rapidly melting the ice layer. The meltwater quickly rolls off under the synergistic effect of the hydrophobic coating and the biomimetic structure, preventing secondary icing and achieving efficient and low-energy de-icing.

[0031] Beneficial effects

[0032] Compared with the prior art, the beneficial effects of the present invention are:

[0033] Biomimetic structures enable passive anti-icing, resulting in a significant improvement in anti-icing performance.

[0034] This invention is the first to integrate the natural biological anti-adhesion and hydrophobic structural features of bee honeycomb, bullfish skin, and butterfly wings into the primary structural design of laser-induced graphene films. By replicating the excellent structural characteristics of biological evolution over millions of years, it maximizes the reduction of solid-ice contact area and ice adhesion strength at the physical topology level. Compared with traditional artificially designed topologies, the passive anti-icing effect is improved by more than 30%, and the freezing time of water droplets is delayed by more than 6 times. It is especially suitable for the anti-icing requirements of photovoltaic modules and can significantly reduce the time that ice layers block photovoltaic panels.

[0035] The synergistic effect of passive anti-icing and active de-icing significantly reduces de-icing energy consumption.

[0036] A passive anti-icing system is constructed using a primary biomimetic topology and a tertiary nano-hydrophobic coating, while an active de-icing system is formed using a secondary porous graphene network. This achieves organic integration and synergistic effect between the two systems. By prioritizing passive anti-icing and supplementing it with active de-icing, the frequency of active de-icing is significantly reduced. Compared to traditional purely active de-icing technologies, de-icing energy consumption is reduced by over 90%, and the low ice adhesion characteristics further enhance active de-icing efficiency, melting a 3mm thick ice layer within minutes. For photovoltaic modules, solar thermal de-icing can be achieved directly using sunlight, eliminating the need for additional power supply and perfectly meeting the energy-saving requirements of photovoltaic power generation.

[0037] The structure is stable, and it exhibits excellent environmental durability and scene adaptability.

[0038] Laser-induced in-situ bonding of graphene layers with polyimide substrates and tertiary nano-hydrophobic coatings with graphene layers via Si-OC covalent bonds enhance the bonding strength by more than 10 times. Meanwhile, targeted biomimetic structural selection adapts to the working conditions of different application scenarios. The film for aerospace wings withstands fluid shear force ≥50Pa, the film for wind turbine blades exhibits performance degradation ≤15% after 1000h of UV aging, and the film for photovoltaic modules shows no significant degradation in hydrophobicity and photothermal conversion performance after long-term outdoor exposure and freeze-thaw cycles, meeting the stringent outdoor use requirements of various fields.

[0039] The manufacturing process is highly controllable, and the biomimetic structure can be customized.

[0040] By controlling the pulsed laser parameters through computer programming, the biological structural features of bee hives, bullfish skin, and butterfly wings can be accurately replicated. The array arrangement, unit size, and shape of the primary biomimetic structure can be flexibly adjusted. At the same time, according to the different needs of aviation, wind power, and photovoltaic scenarios, the matching biomimetic structure can be selected to achieve customized design and adapt to the different chemical conditions in various fields.

[0041] The preparation process is green and simple, and suitable for industrial production.

[0042] The entire preparation process uses polyimide film as raw material and generates LIG layer and primary biomimetic structure in situ in one step by pulsed laser scanning. It does not require complicated chemical etching, template preparation or material transfer steps, and is environmentally friendly. The subsequent hydrophobic modification and annealing are conventional industrial processes with mild conditions, simple operation, controllable process parameters, good product consistency, and good prospects for large-scale industrial production. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 This is a schematic diagram of the preparation method in Embodiment 1 of the present invention.

[0045] Figure 2 This is a schematic diagram of the biomimetic multi-level structure of the present invention, wherein 1-polyimide substrate, 2-first-level biomimetic structure (imitating bee honeycomb / imitating bull horn fish skin / imitating butterfly wings), 3-second-level three-dimensional porous graphene network, and 4-third-level nano-hydrophobic coating.

[0046] Figure 3 These are schematic diagrams of the microstructures of the three primary biomimetic structures of this invention;

[0047] Figure 4 This is a graph showing the water contact angle test results of the composite film of the present invention. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0049] In this document, terms such as "upper," "lower," "inner," and "outer" are established based on the positional relationships shown in the accompanying drawings. Depending on the drawings, the corresponding positional relationships may also change. Therefore, they should not be interpreted as an absolute limitation on the scope of protection. Moreover, relational terms such as "first" and "second" are only used to distinguish one component from another that has the same name, and do not necessarily require or imply any such actual relationship or order between these components.

[0050] Example 1, such as Figure 1 As shown, a synergistic anti-icing and de-icing preparation method for laser-induced graphene composite films based on biomimetic multi-level structures is proposed, including the following steps:

[0051] Step 1: Provide a polyimide film substrate and perform surface pretreatment;

[0052] The polyimide film described in this embodiment is a homopolymer or biphenyl polyimide; the surface pretreatment includes:

[0053] Step 1 and 2: Cleaning: Place the polyimide film in anhydrous ethanol and deionized water in sequence, and perform ultrasonic cleaning treatment for 5-20 minutes each time to ensure that organic pollutants, dust and inorganic salts and other impurities on its surface are completely removed and the surface is clean.

[0054] Step 13, Drying: Remove the cleaned polyimide film from the deionized water and blow it with high-purity nitrogen to remove most of the water stains. Then transfer it to a constant temperature drying oven and dry it at 60-80℃ for 10-40 minutes to completely remove the physically adsorbed moisture on the surface and avoid interference with the formation of the microstructure due to moisture vaporization during subsequent laser processing.

[0055] Step 2: Selectively scan the pretreated polyimide film substrate surface using a pulsed laser. Through laser-induced carbonization reaction, a laser-induced graphene layer is simultaneously generated in situ on the substrate surface, and a biomimetic multi-level structure is constructed.

[0056] In this embodiment, the wavelength, power, scanning speed, and scanning path of the pulsed laser are precisely controlled by a computer program to ensure that the laser energy density and action time are matched with the carbonization threshold of the polyimide surface, thereby achieving in-situ induction of high-quality graphene without damaging the overall structure and mechanical integrity of the substrate.

[0057] The specific biomimetic multi-level structures constructed include:

[0058] (a) Primary structure: periodic micro-topological pattern; specifically, the micro-topological pattern described in this embodiment is a micron-scale array of protrusions or pits; the structure is formed by laser selective ablation (for pits) or induced material expansion / recasting (for protrusions), aiming to physically reduce the actual contact area between ice crystals and the material surface, thereby reducing the ice adhesion strength.

[0059] (b) Secondary structure: a three-dimensional porous graphene network formed on the surface of the primary structure and in the exposed area of ​​the substrate; this structure is a porous graphene foam layer that is naturally formed during the laser-induced carbonization of polyimide, with extremely high specific surface area and pore structure, providing photothermal conversion capability for efficient absorption of light energy and conversion into heat energy.

[0060] This example controls the arrangement, unit size (such as diameter, depth or height, and spacing), and overall shape of the periodic array in the primary structure by adjusting the scanning path parameters of the pulsed laser. Specifically, the arrangement of the periodic array can be programmably set to a square array or a regular hexagonal array. For example, a regular hexagonal array can be used for applications requiring maximum structural strength and uniformity (such as the surface of an airfoil subjected to fluid shear forces); a square array can be used for applications requiring simplified processing paths or adaptation to specific directional requirements. The coordinated adjustment of laser parameters (such as power density and scanning speed) directly determines the porosity, layer thickness, and conductivity of the three-dimensional porous graphene network in the secondary structure, thereby controlling its final photothermal conversion efficiency.

[0061] Step 3: The product after step 2 is immersed in a nano-hydrophobic layer solution for hydrophobic modification, and then cured to form a tertiary nano-hydrophobic coating attached to the surface of the laser-induced graphene layer.

[0062] In this embodiment, the biomimetic multi-level structured film is completely immersed in a pre-prepared nano-hydrophobic coating solution, ensuring that the solution fully wets and penetrates into its surface and the interior of the three-dimensional porous structure. The immersion time can be controlled according to the thickness and uniformity requirements of the target coating, typically 1-10 minutes.

[0063] The nano-hydrophobic coating solution described in this embodiment is a solution formed by dissolving fluorinated silanes (such as heptadecafluorodecyltrimethoxysilane) or perfluoroalkyl silanes in an organic solvent (such as a mixture of isopropanol, ethanol, and water), with a concentration range generally from 0.5% to 5% (v / v). This solution aims to induce hydrolysis-condensation reactions of fluorinated / perfluoroalkyl silane molecules on the LIG surface and pore walls through chemical vapor deposition or solution impregnation, forming an ultrathin nano-coating bonded by covalent bonds (Si-OC).

[0064] After impregnation, the film is carefully removed and suspended vertically or tilted at a specific angle in a clean environment, allowing excess solution to flow away naturally under gravity, preventing uneven coating buildup. The film is then transferred to a constant-temperature oven for curing. The curing temperature is typically set between 80°C and 150°C, with a curing time ranging from 30 minutes to 2 hours. This process aims to promote further cross-linking and chemical bonding of silane molecules, firmly anchoring the nano-hydrophobic coating to the network surface. This imparts excellent superhydrophobic properties to the entire composite film (water contact angle typically greater than 150°, roll-off angle less than 10°), and effectively protects the internal graphene structure from environmental moisture, salt spray, and other corrosive media.

[0065] Step 4: The material treated in Step 3 is annealed under an inert gas atmosphere to eliminate internal stress. After cooling, the laser-induced graphene composite film is obtained.

[0066] In this embodiment, the hydrophobically modified and cured film is placed in a tube furnace or vacuum annealing furnace and annealed under a protective atmosphere of inert gas (such as high-purity argon or nitrogen). The flow rate of the inert gas needs to be kept stable to ensure complete removal of oxygen and moisture from the furnace chamber and to prevent oxidative damage to the graphene structure at high temperatures.

[0067] Tests have verified that this composite film possesses excellent comprehensive anti-icing and de-icing properties: its surface exhibits a high water contact angle (>150°) and a low roll-off angle (<10°), demonstrating superhydrophobic characteristics; in a low-temperature environment of -15°C, the freezing time of water droplets on its surface is significantly delayed; and the adhesion strength of ice layers on its surface is extremely low. Under simulated sunlight irradiation, the film can rapidly heat up and completely melt a 3mm thick layer of ice adhering to its surface within a short time (e.g., within minutes). Furthermore, after multiple (e.g., more than 50) freeze-thaw cycles and friction tests (e.g., Taber abrasion resistance tests), the aforementioned superhydrophobicity and photothermal de-icing properties remain stable, demonstrating its good environmental durability and service life.

[0068] Annealing process parameters: The annealing temperature is typically set between 200℃ and 350℃, with a heating rate of 2℃ / min to 10℃ / min, and held at the target temperature for 30 minutes to 2 hours. This gentle annealing process serves a dual purpose: firstly, it eliminates the internal stress accumulated within the material during the aforementioned laser processing and curing steps through thermal relaxation, thereby improving the overall dimensional stability and mechanical reliability of the film; secondly, it further promotes the chemical stabilization of the interface between the nano-hydrophobic coating and the substrate, enhancing the bonding strength.

[0069] After the annealing process, the sample is allowed to cool naturally to room temperature in the furnace (cooling rate is typically less than 5°C / min) to avoid film curling or coating cracking due to sudden changes in thermal stress. After cooling, it is removed in an inert atmosphere or a dry environment, yielding a structurally intact and stable laser-induced graphene composite film based on a biomimetic hierarchical structure. This film combines long-lasting superhydrophobicity, extremely low ice adhesion strength, and high-efficiency photothermal conversion capability, all conferred by the synergistic effect of the hierarchical structure, and can be applied directly or after further processing to target anti-icing and de-icing scenarios.

[0070] Example 2: A laser-induced graphene composite film based on a biomimetic multi-level structure is provided, wherein the film comprises, from the inside out:

[0071] Polyimide film substrate; the substrate is selected from homopolymer or biphenyl polyimide, which has excellent high temperature resistance, flexibility and dimensional stability, providing a flat and solid support for the construction of subsequent functional layers.

[0072] A laser-induced graphene layer is formed on the surface of the substrate, comprising a primary periodic array of micron-sized bumps / pits and a secondary three-dimensional porous graphene network formed thereon; this layer is generated in situ on the surface of the polyimide substrate by the method described in Example 1. Its core feature lies in its integrated biomimetic multi-level structure:

[0073] Primary structure: Periodic micron-sized protrusion / pit array. This array is formed by laser-programmed scanning, and its arrangement (such as square, regular hexagon) and unit size (protrusion height / pit depth, spacing) can be designed according to the anti-icing mechanism requirements, aiming to physically maximize the reduction of the contact area between ice crystals and the substrate.

[0074] Secondary structure: Three-dimensional porous graphene network. This network forms on the surface of the primary structure and in the exposed areas of the substrate. It is a porous, foam-like graphene layer naturally formed by laser-induced carbonization. It has an extremely high specific surface area and abundant nanoscale pores, providing active area for surface chemical modification and constituting a highly efficient photothermal conversion capability.

[0075] A tertiary nano-hydrophobic coating is attached to the surface of the laser-induced graphene layer. This coating is chemically modified (e.g., by hydrolysis-condensation of fluorinated / perfluoroalkyl silanes) and covalently bonded to the entire surface and pore walls of the laser-induced graphene layer. This ultrathin coating significantly reduces the surface energy of the material.

[0076] The composite film prepared in this embodiment exhibits the following comprehensive properties through the synergistic effect of the above-mentioned three-level structure:

[0077] Superhydrophobic: Its surface water contact angle is usually greater than 150° and the roll-off angle is less than 10°, which can effectively repel water droplets and significantly delay the freezing process.

[0078] Low ice adhesion strength: Due to the reduction of the actual contact area by the micron array, coupled with the effect of the superhydrophobic surface, the adhesion strength between the ice layer and the film is significantly reduced, making it easy to detach under gravity or slight external force.

[0079] Highly efficient photothermal conversion capability: The internal three-dimensional porous graphene network can efficiently absorb broadband light energy (especially sunlight) and quickly convert it into heat energy, enabling the film to heat up rapidly under light and achieve active de-icing.

[0080] The film has a stable structure. After the annealing treatment described in step four of Example 1, the internal stress is eliminated and the interfacial bonding is enhanced, ensuring that its performance degradation is minimal after multiple freeze-thaw cycles and mechanical friction tests, and thus it has a long service life.

[0081] Example 3: Application of laser-induced graphene composite films for anti-icing and de-icing on the leading edges of aircraft wings, wind turbine blades, or solar photovoltaic modules. This composite film can be directly bonded or integrated onto the surfaces of critical equipment such as aircraft wing leading edges, wind turbine blades, or solar photovoltaic modules using suitable adhesives. These devices collectively face the challenge of icing in outdoor environments, creating an urgent need for efficient, low-energy, and long-life anti-icing and de-icing measures.

[0082] Preparation of honeycomb-structured composite films for the leading edge of aircraft wings

[0083] Substrate pretreatment: A 100μm thick homopolymer polyimide film was selected and ultrasonically cleaned in anhydrous ethanol and deionized water for 15 min each. After being dried with high-purity nitrogen, it was dried at 70℃ for 20 min to obtain a clean substrate.

[0084] Laser-based biomimetic multi-level structure construction: Using a 1064nm fiber pulsed laser with a power of 12W, a scanning speed of 200mm / s, and a scanning spacing of 25μm, a regular hexagonal path is used to construct a honeycomb-like structure. The primary structure is a regular hexagonal micron columnar protrusion array (the distance between the sides of the column is 20μm, the height is 15μm, and the array period is 30μm). The secondary structure is a three-dimensional porous graphene network with a porosity of 75%.

[0085] Hydrophobic modification: The product was immersed in a 2% v / v mixed solution of heptadecafluorodecyltrimethoxysilane isopropanol-ethanol-water (volume ratio 8:1:1) for 5 min. After removing the excess solution, it was cured at 100℃ for 1 h to form a tertiary nanohydrophobic coating with a thickness of 100 nm.

[0086] Annealing: Under the protection of high-purity argon, the temperature is increased to 280°C at a rate of 5°C / min and held for 1 hour. Then, it is cooled to room temperature at a rate of 3°C / min to obtain a composite film for the leading edge of an aircraft wing.

[0087] Performance testing: The film has a water contact angle of 157°, a roll-off angle of 3°, an ice adhesion strength of 16 kPa at -15°C, and a photothermal conversion efficiency of 89% in the 200-2500nm wavelength band; it is resistant to fluid shear force ≥55Pa, and after 50 freeze-thaw cycles, the water contact angle is 152° and the photothermal conversion efficiency is 86%, with performance degradation meeting the requirements for use in the aerospace field.

[0088] Preparation of composite films with a bullhorn-fish-like skin structure for wind turbine blades

[0089] Substrate pretreatment: A 100μm thick biphenyl polyimide film was selected and ultrasonically cleaned in anhydrous ethanol and deionized water for 20 min each. After being dried with high-purity nitrogen, it was dried at 80℃ for 30 min to obtain a clean substrate.

[0090] Laser-based construction of biomimetic multi-level structures: Using a CO2 pulsed laser with a power of 10W, a scanning speed of 150mm / s, and a scanning spacing of 20μm, scanning along a dot matrix path, the primary structure of the horned fish-like skin is constructed as a near-circular micron-sized protrusion array (protrusion diameter 15μm, height 12μm, array period 25μm), and the secondary structure is a three-dimensional porous graphene network with a porosity of 70%.

[0091] Hydrophobic modification: The product was immersed in a 3% v / v mixed solution of heptadecafluorodecyltrimethoxysilane for 8 min, and after removing the excess solution, it was cured at 120℃ for 1.5 h to form a tertiary nano-hydrophobic coating with a thickness of 150 nm.

[0092] Annealing treatment: Under the protection of high-purity nitrogen, the temperature is raised to 300℃ at a rate of 4℃ / min and held for 1.5h. Then, it is cooled to room temperature at a rate of 4℃ / min to obtain the composite film for wind turbine blades.

[0093] Performance testing: The film has a water contact angle of 158°, a roll-off angle of 4°, an ice adhesion strength of 18 kPa at -15°C, and a photothermal conversion efficiency of 87%. After 1000 hours of UV aging, its performance degrades by 12%. After 50 freeze-thaw cycles, the water contact angle is 151° and the photothermal conversion efficiency is 84%, making it suitable for harsh outdoor working conditions of wind turbine blades.

[0094] Preparation of butterfly wing-inspired composite thin films for solar photovoltaic modules

[0095] Substrate pretreatment: A 60μm thick homopolymer polyimide film (high transmittance adaptable type) was selected, and ultrasonically cleaned in anhydrous ethanol and deionized water for 10 min each. After being dried with high-purity nitrogen, it was dried at 60℃ for 15 min to obtain a clean substrate.

[0096] Laser-based biomimetic multi-level structure construction: A 1064nm fiber pulsed laser with a power of 8W, a scanning speed of 250mm / s, and a scanning spacing of 15μm was used to scan along a stripe path to construct a butterfly wing-like primary structure, which is a striped micro-nano pit array (pit width 10μm, depth 8μm, stripe period 20μm). The secondary structure is a three-dimensional porous graphene network with a porosity of 80%.

[0097] Hydrophobic modification: The product was immersed in a 1% v / v mixed solution of heptadecafluorodecyltrimethoxysilane for 3 min, and after removing the excess solution, it was cured at 90℃ for 40 min to form a tertiary nanohydrophobic coating with a thickness of 80 nm.

[0098] Annealing treatment: Under the protection of high-purity argon, the temperature is raised to 250°C at a rate of 3°C / min and held for 2 hours. Then, it is cooled to room temperature at a rate of 2°C / min to obtain the composite thin film for solar photovoltaic modules.

[0099] Performance testing: The film has a water contact angle of 159°, a roll-off angle of 3°, an ice adhesion strength of 17kPa at -15℃, and a photothermal conversion efficiency of 88% in the 200-2500nm wavelength band. It has excellent light transmittance, with an impact of ≤3% on the photoelectric conversion efficiency of photovoltaic modules. After 1000 hours of outdoor exposure and 50 freeze-thaw cycles, the water contact angle is 153°, the photothermal conversion efficiency is 85%, and there is no coating peeling or structural cracking, meeting the requirements for long-term outdoor use of solar photovoltaic modules.

[0100] Industrial applicability

[0101] This invention presents a synergistic anti-icing and de-icing preparation method for laser-induced graphene composite films with biomimetic multi-level structures inspired by bee honeycombs, bull horn fish skin, and butterfly wings. The process is simple, highly controllable, and environmentally friendly, enabling large-scale industrial production. The resulting composite film significantly enhances passive anti-icing performance through its biomimetic structure, while also synergistically enhancing active de-icing capabilities. It exhibits excellent environmental durability and scenario adaptability, making it widely applicable to anti-icing and de-icing of aircraft wing leading edges, wind turbine blades, and solar photovoltaic modules. This method solves the problems of high energy consumption, poor durability, and functional fragmentation in existing anti-icing and de-icing technologies in the aviation, wind power, and photovoltaic fields, demonstrating significant industrial applicability and broad industrialization prospects in these high-end equipment sectors.

[0102] Scope of protection of this invention

[0103] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, preferably sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, if the method may also include step (c), it means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0104] In the description of this application, it should be noted that, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," etc., indicating orientation or positional relationships are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0105] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0106] Unless otherwise specified, the terms "comprising" and "including" as used in this application are open-ended. For example, "comprising" and "including" can mean including or containing other components not listed.

[0107] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0108] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0109] Without contradicting the spirit and technical means of this invention, at least some of the technical implementation methods in the embodiments may be combined or substituted. Although the invention has been described with respect to a limited number of embodiments, those skilled in the art will understand from the above description that other embodiments can be conceived 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 instructional purposes, and not for 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 this invention is illustrative and not restrictive, and the scope of the invention is defined by the appended claims.

Claims

1. A method for preparing a synergistic anti-icing and de-icing process of a laser-induced graphene composite film based on a biomimetic multi-level structure, characterized in that, The synergistic effect of passive anti-icing and active de-icing is achieved through a biomimetic multi-level structural design, including the following steps: S1. Provide a polyimide film substrate and perform surface pretreatment; S2. A pulsed laser is used to selectively scan the surface of the pretreated polyimide film substrate. Through laser-induced carbonization, a laser-induced graphene layer is simultaneously generated in situ on the substrate surface, and a biomimetic multi-level structure is constructed. The structure respectively carries passive anti-icing and active de-icing functions: (a) Primary structure: a periodic micro-topological pattern of at least one of the following: a regular hexagonal array of bee honeycomb, a micro-protrusion array of bull horn fish skin, or a micro-nano pit array of butterfly wings. (b) Secondary structure: a three-dimensional porous graphene network with a porosity of 60%-85% formed on the surface of the primary structure and in the exposed area of ​​the substrate; S3. The product treated in S2 is immersed in a nano-hydrophobic layer solution with a concentration of 0.5%-5% v / v for hydrophobic modification. The immersion modification time is 1-10 min, followed by curing at 80-150℃ for 30 min-2 h to form a tertiary nano-hydrophobic coating with a thickness of 50-200 nm that is bonded to the graphene layer through Si-OC covalent bonds and attached to the surface of the laser-induced graphene layer. S4. The material treated in S3 is placed under an inert gas protection for annealing treatment. The temperature is raised to 200-350℃ at a heating rate of 2-10℃ / min and held for 30min-2h to eliminate the internal stress of the structure. After cooling at a rate of ≤5℃ / min, the laser-induced graphene composite film is obtained.

2. The preparation method according to claim 1, characterized in that, In step S1, the polyimide film is a homophenylene or biphenyl polyimide; the surface pretreatment involves placing the polyimide film in anhydrous ethanol and deionized water for ultrasonic cleaning for 5-20 minutes, drying it with high-purity nitrogen, and then drying it at 60-80°C for 10-40 minutes.

3. The preparation method according to claim 1, characterized in that, In step S2, by adjusting the scanning path parameters, scanning spacing and power parameters of the pulsed laser, the arrangement, size and shape of the periodic array in the primary structure are controlled to match the structural features of a bee honeycomb, a bull horn fish skin or a butterfly wing.

4. The preparation method according to claim 3, characterized in that, The primary structure of the bee-like honeycomb is a regular hexagonal array of micro-pits or protrusions; the primary structure of the bull hornfish-like skin is a near-circular array of micro-protrusions; and the primary structure of the butterfly-like wing is a striped array of micro-nano pits.

5. The preparation method according to claim 1, characterized in that, In step S2, the micron-unit feature size of the first-level biomimetic micro-topological pattern is 5-30 μm, and the array period is 5-50 μm; the micro-topological pattern is a micron-scale protrusion array or pit array.

6. The preparation method according to claim 1, characterized in that, In step S3, the nano-hydrophobic coating solution is a solvent system of fluorinated silane or perfluoroalkyl silane; the fluorinated silane is heptadecafluorodecyltrimethoxysilane, the solvent is a mixture of isopropanol, ethanol and water, and the impregnation modification time is 1-10 min.

7. A laser-induced graphene composite film based on a biomimetic multi-level structure, characterized in that, The thin film comprises, from the inside out, the following: Polyimide film substrate; A laser-induced graphene layer is formed on the surface of the substrate. The laser-induced graphene layer is generated and bonded to the substrate in situ, and includes a primary periodic array of micron-sized protrusions or pits that mimic the honeycomb, the skin of a bullfish, or the wings of a butterfly, and a secondary three-dimensional porous graphene network formed therefrom. And a tertiary nanohydrophobic coating with a thickness of 50-200 nm, attached to the surface of the laser-induced graphene layer and bonded to the graphene layer by Si-OC covalent bonds.

8. The composite film according to claim 7, characterized in that, The film exhibits superhydrophobicity, low ice adhesion strength, and photothermal conversion capability; the superhydrophobicity is characterized by a water contact angle ≥150° and a roll-off angle ≤10°, the low ice adhesion strength is ≤20kPa, and the photothermal conversion efficiency is ≥85%; after 50 freeze-thaw cycles or Taber abrasion tests, the water contact angle decreases by ≤10° and the photothermal conversion efficiency decreases by ≤5%.

9. The use of a laser-induced graphene composite film as described in claim 7 or 8 for de-icing on the leading edge of an aircraft wing, a wind turbine blade, or the surface of a solar photovoltaic module.

10. The use according to claim 9, characterized in that, Based on the curvature, stress conditions, and icing characteristics of different application substrates, matching primary biomimetic structures such as bee honeycomb, bull horn fish skin, and butterfly wings are selected. By adjusting the pulsed laser scanning path and / or parameters, the primary biomimetic topological array morphology of the composite film is adapted to the surface of application substrates with different curvatures. The film used for the leading edge of the aircraft wing has a fluid shear force resistance ≥50Pa, the film used for the wind turbine blade has a performance degradation ≤15% after 1000h of ultraviolet aging, and the film used for the solar photovoltaic module has a freeze-thaw cycle resistance ≥100 times with an impact on photoelectric conversion efficiency ≤3%.

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