Photo-thermal printing ink as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of photo-thermal ink coatings, and particularly relates to a preparation method of a photo-thermal ink coating. The photo-thermal printing ink is obtained by mixing and reacting 40-100 parts of photo-thermal suspension liquid, 5-10 parts of Arabic gum and 8-16 parts of glycerinum. Wherein the photo-thermal suspension is obtained by mixing cellulose nanofibers, ferroferric oxide / multi-walled carbon nanotubes, methyltrimethoxysilane and ammonia water, and reacting to form a siloxane bonding network. The ferroferric oxide / multi-walled carbon nanotube is obtained by reacting an aminated multi-walled carbon nanotube and nano ferroferric oxide according to a mass ratio of 1: (0.5-1). According to the photo-thermal ink, through surface amination modification and multi-component synergy, the wide spectrum absorptivity reaches 88.9%, and the photo-thermal ink has excellent photo-thermal conversion efficiency and substrate adhesion and is suitable for photo-thermal conversion and functional surface construction.

Description

Technical Field

[0001] This invention belongs to the field of photothermal ink coating technology, specifically relating to a photothermal ink, its preparation method, and its application. Background Technology

[0002] In recent years, with the advancement of solar-driven water harvesting, thermal regulation, and thermal energy conversion applications, higher demands have been placed on photothermal coatings that combine high-efficiency absorption, stable dispersion, and easy processing into films. Carbon-based nanomaterials, especially multi-walled carbon nanotubes (MWCNTs), have attracted attention due to their broad-spectrum absorption and excellent thermal transport. Magnesium oxide (Fe3O4), as a typical magnetic metal oxide, possesses chemical stability and tunable structure, showing potential applications in near-infrared light and thermal conversion.

[0003] In existing technologies, multi-walled carbon nanotubes and iron oxide (Fe3O4) are typically introduced into aqueous or organic systems in an unmodified or simply physically mixed form. These aqueous or organic systems often exhibit low solvent evaporation rates and long film-forming times. In such systems, due to the high surface energy, significant van der Waals interactions, and magnetic attraction of the nanomaterials, the nanomaterials are more prone to aggregation and sedimentation during dispersion and film formation without effective interface control. This results in uneven distribution of photothermal components, localized sedimentation, or film defects in the coating, affecting its uniformity.

[0004] Therefore, existing photothermal coating materials cannot simultaneously achieve uniform dispersion of nano-components and anchor them to the interface in aqueous or organic systems. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a photothermal ink, its preparation method, and its application.

[0006] To facilitate understanding of the present invention, the substances used in the present invention and their abbreviations are listed below: Multi-walled carbon nanotubes (MWCNTs). 3-Aminopropyltriethoxysilane (APTES). Cellulose nanofibers (CNF). Methyltrimethoxysilane (MTMS). Aminated carbon nanotubes (NCNTs). Aminated carbon nanotube / nano-iron oxide composite material (NCNT / F). Iron oxide / multi-walled carbon nanotubes (NCNT / Fe3O4).

[0007] The first objective of this invention is to provide a photothermal ink obtained by mixing and reacting 40 to 100 parts of a photothermal suspension, 5 to 10 parts of gum arabic, and 8 to 16 parts of glycerol.

[0008] The photothermal suspension is obtained by mixing cellulose nanofibers, iron oxide / multi-walled carbon nanotubes, methyltrimethoxysilane and ammonia, reacting them to form a siloxane bonding network.

[0009] The iron oxide / multi-walled carbon nanotubes are obtained by reacting aminated multi-walled carbon nanotubes and nano-iron oxide at a mass ratio of 1:0.5~1.

[0010] A second objective of this invention is to provide a method for preparing photothermal ink, comprising the following steps: Multi-walled carbon nanotubes and 3-aminopropyltriethoxysilane were dissolved in an organic solvent at a mass ratio of 100:1~5, and after stirring, aminated multi-walled carbon nanotubes were obtained.

[0011] Aminated multi-walled carbon nanotubes and nano-ferric oxide were dissolved in an organic solvent at a mass ratio of 1:0.5~1, and after stirring and reaction, ferric oxide / multi-walled carbon nanotubes were obtained.

[0012] By weight, 25-50 parts of a cellulose nanofiber suspension with a concentration of 5 mg / mL-10 mg / mL, 25-50 parts of a ferric oxide / multi-walled carbon nanotube solution with a concentration of 5 mg / mL-10 mg / mL, 0.5-1.0 parts of methyltrimethoxysilane, and 0.01-0.05 parts of ammonia water are mixed and stirred for reaction three times to obtain a photothermal suspension.

[0013] By weight, 40 to 100 parts of photothermal suspension, 5 to 10 parts of gum arabic, and 8 to 16 parts of glycerin are mixed and stirred to obtain photothermal ink material.

[0014] Preferably, the mass ratio of the multi-walled carbon nanotubes to 3-aminopropyltriethoxysilane is 100:3.

[0015] Preferably, the organic solvent is anhydrous ethanol.

[0016] Preferably, the mass ratio of the aminated multi-walled carbon nanotubes to iron oxide is 1:0.5~1.

[0017] Preferably, the concentration of the cellulose nanofiber suspension is 8 mg / mL, the concentration of the iron oxide / multi-walled carbon nanotube dispersion is 8 mg / mL, and the weight ratio of cellulose nanofiber suspension: iron oxide / multi-walled carbon nanotube dispersion: methyltrimethoxysilane: ammonia is 40:40:0.8:0.03.

[0018] Preferably, the conditions for the first stirring reaction are a temperature of 30℃~50℃, a stirring speed of 400rpm~800rpm, and a reaction time of 4h~10h; The conditions for the second stirring reaction are a temperature of 30℃~50℃, a speed of 400rpm~800rpm, and a reaction time of 4h~10h. The conditions for the stirring reaction 3 are a temperature of 30℃~50℃, a speed of 400rpm~800rpm, and a reaction time of 4h~10h; The conditions for the stirring reaction four are a temperature of 30℃~50℃, a speed of 400rpm~800rpm, and a reaction time of 4h~10h.

[0019] Preferably, the conditions for the first stirring reaction are a temperature of 45°C, a stirring speed of 800 rpm, and a reaction time of 10 h. The conditions for the second stirring reaction are: temperature 40°C, stirring speed 800 rpm, and reaction time 6 h. The conditions for the third stirring reaction are: temperature 40°C, stirring speed 600 rpm, and reaction time 6 h. The conditions for the fourth stirring reaction are a temperature of 40°C, a stirring speed of 600 rpm, and a reaction time of 8 hours.

[0020] Preferably, the weight ratio of the photothermal suspension, gum arabic, and glycerol is 50:8:12.

[0021] The third objective of this invention is to provide an application of photothermal ink in the preparation of solar-driven atmospheric water collection and interfacial water evaporation products.

[0022] Compared with the prior art, the present invention has the following beneficial effects: 1. The photothermal ink of the present invention is obtained by mixing and reacting 40-100 parts of photothermal suspension, 5-10 parts of gum arabic, and 8-16 parts of glycerol. The photothermal suspension is obtained by mixing cellulose nanofibers, iron(III) oxide / multi-walled carbon nanotubes, methyltrimethoxysilane, and ammonia to form a siloxane bonding network. The iron(III) oxide / multi-walled carbon nanotubes are obtained by reacting aminated multi-walled carbon nanotubes and nano-iron(III) oxide at a mass ratio of 1:0.5-1. In the photothermal ink of the present invention, gum arabic and glycerol provide macroscopic adhesion and flexibility, PMSQ provides water resistance and durability, and NCNT / Fe3O4 / CNF provides light absorption, thermal conductivity, and skeletal support. These three components synergistically produce a photothermal coating with high absorption, low reflection, crack resistance, and durability. Furthermore, the nano-components are uniformly dispersed and anchored to an effective interface in aqueous or organic systems to form a film.

[0023] In Application Example 1 of this invention, the balsa wood substrate is wood loaded with LiCl hygroscopic salts, simulating the actual atmospheric water capture and evaporation working environment. The temperature is stabilized at 57°C due to the heat absorption limitation caused by water evaporation. In Application Example 2, the balsa wood substrate does not have water evaporation carrying away heat, and the temperature can reach 87°C. This demonstrates that the photothermal ink of this invention has universality, capable of generating high temperatures not only under dry conditions but also operating stably in humid and high-salt environments.

[0024] 2. The preparation method of the photothermal ink of the present invention involves dissolving multi-walled carbon nanotubes (MWCNTs) and 3-aminopropyltriethoxysilane in an organic solvent at a mass ratio of 100:1-5, followed by stirring and reaction one step to obtain aminated MWCNTs. The introduction of –NH2 / Si–O– anchoring on the MWCNT surface by 3-aminopropyltriethoxysilane enhances the dispersibility of MWCNTs in polar media and improves the interfacial bonding ability of the substrate. 3-aminopropyltriethoxysilane hydrolyzes to silanol in an alcohol or microaqueous environment, subsequently condensing with oxygen-containing functional groups on the CNT surface to generate a Si–O–C / Si–O–Si anchoring layer. Exposed amino groups facilitate hydrogen bonding or further condensation with PMSQ or polysaccharides. However, excessively low mass fractions of 3-aminopropyltriethoxysilane lead to insufficient functionalization and easy aggregation, while excessively high mass fractions result in self-condensation and deterioration of dispersion. Mild reaction conditions promote hydrolysis and condensation, avoiding excessively rapid self-polymerization. Surface anchoring enables more uniform dispersion of MWCNTs in subsequent aqueous and alcoholic systems, and creates thermally conductive channels with low interfacial thermal resistance and stable chemical and physical adhesion during film formation. APTES gently couples the MWCNT surface, while introducing a CNF aqueous suspension system provides green dispersion and rheological support. This combination of coupling, sol, gel, and nanofiber support ensures both stable dispersion of nanocomponents and strong interfacial bonding between the coating and the substrate.

[0025] Aminated multi-walled carbon nanotubes (MWCNTs) and nano-Fe3O4 were dissolved in an organic solvent at a mass ratio of 1:0.5-1. After stirring and reacting, a composite material of iron(III) oxide (Fe3O4) and NCNTs was obtained. The reaction of aminated MWCNTs and nano-Fe3O4 constructs a nanocomposite of a linear thermally conductive framework of MWCNTs and point-like absorption centers of nano-Fe3O4, enhancing the broad-spectrum absorption and thermal diffusion of the ink. Nano-Fe3O4 and NCNTs form heterogeneous contacts through weak interactions such as van der Waals, hydrogen bonding, and coordination. Well-dispersed particles can generate effective non-radiative relaxation under illumination and couple heat to the CNT framework. Too low a ratio of nano-Fe3O4 to NCNTs leads to insufficient absorption centers, while too high a ratio results in enhanced particle scattering, film embrittlement, and increased risk of agglomeration. The introduction of Fe3O4 broadens near-infrared absorption and acts as a hotspot, while MWCNTs ensure continuous thermal diffusion. The synergy between the two results in a faster temperature rise and more uniform photothermal response. The photothermal ink of this invention forms a multi-scale coupled network of linear thermally conductive framework and point-like absorption centers by compositing aminated multi-walled carbon nanotubes with nano-ferric oxide. This achieves stable and continuous energy capture and non-radiative relaxation in the ultraviolet, visible, and near-infrared bands, thereby improving photothermal conversion efficiency and temperature rise rate.

[0026] A photothermal suspension was obtained by mixing 25-50 mL of a cellulose nanofiber suspension (5 mg / mL-10 mg / mL), a ferric oxide / multi-walled carbon nanotube solution (5 mg / mL-10 mg / mL), 0.5-1.0 mL of methyltrimethoxysilane, and 0.01-0.05 g of ammonia water and stirring for three reactions. CNF was used to provide green dispersion and rheological support. MTMS was introduced to form PMSQ adhesive bridges in situ under alkaline catalysis, "spot-welding" the nanocomponents into a continuous network, resulting in a coatable and stable suspension system. CNF has a high specific surface area and abundant hydroxyl groups, which can provide more hydrogen bonds, increase ink viscosity and thixotropy, and inhibit sedimentation. MTMS and ammonia water catalyzed the hydrolysis of silanols, further condensing PMSQ. PMSQ formed a Si–O–Si / Si–O–C / hydrogen bond composite adhesive network between NCNT / Fe3O4 / CNF / substrate. The PMSQ network fixes and uniformly embeds nano-components into the binder phase, improving water resistance, durability, and adhesion. CNF provides "nano-ribs" and suitable application rheological properties to ensure a uniform and dense coating.

[0027] A photothermal suspension, gum arabic, and glycerol are mixed at a mass ratio of 40-100:5-10:8-16 and reacted at 25-40°C and 400-800 rpm for 4-10 hours to obtain the photothermal ink material. The composite of the photothermal suspension, gum arabic, and glycerol gives the ink properties of strong adhesion, flexibility, crack resistance, and workability. Gum arabic is a polysaccharide and polypeptide composite colloid that provides good wetting and film-forming adhesion, forming multi-point hydrogen bonds with CNF / NCNT surfaces. Glycerol lowers the glass transition temperature, alleviates drying shrinkage stress, and improves flexibility and crack resistance. Too low a glycerol ratio leads to brittleness, while too high a ratio results in sticky surfaces and reduced water resistance. The gum arabic and glycerol composite system provides film-forming adhesion and flexible plasticizing, and combined with the water-resistant adhesive properties of PMSQ, makes the coating less prone to cracking and powdering on porous or rough substrates, thus helping to maintain long-term photothermal performance and stable appearance.

[0028] 3. The photothermal ink of this invention features a mild process, simplified steps, and ease of large-scale application. The entire process is primarily solution-based, with key reactions completed at ambient pressure and mild temperatures. The raw materials are compatible with a water / alcohol system and contain environmentally friendly components such as CNF, gum arabic, and glycerol, exhibiting good engineering scale-up and environmental friendliness. Furthermore, the photothermal ink of this invention can be stably stored at room temperature for ≥30 days. Before use, a short period of heating and stirring restores its fluidity, making it suitable for common processes such as brush coating and scraping coating. It can be used for solar-driven atmospheric water harvesting, thermal management, and the preparation of related functional surfaces. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 The images show the surface heat absorption of the wood-based moisture-absorbing composite material before and after coating with the photothermal ink prepared in Example 1 of this invention. In the images, a is the temperature rise curve, and b is an infrared thermal image.

[0031] Figure 2 Temperature rise curves of the wood-based moisture-absorbing composite material surface under simulated sunlight before and after coating with the photothermal ink prepared in Example 1 of the present invention.

[0032] Figure 3 The images show the morphology of the photothermal ink prepared in Example 1 of this invention coated on the surface of a balsa wood substrate. Image a is a scanning electron microscope (SEM) image, and image b is a partial SEM image.

[0033] Figure 4Microscopic morphology of a wood cross-section after being coated with photothermal ink prepared in Example 1 of the present invention.

[0034] Figure 5 The graphs show the reflectance, transmittance, and absorptance of the photothermal ink coating prepared in Example 1 of this invention. Wherein, a represents reflectance, b represents transmittance, and c represents absorptance. Detailed Implementation

[0035] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise specified, the experimental methods described in the embodiments of the present invention are conventional methods, and the materials and reagents used in the following embodiments are commercially available unless otherwise specified.

[0036] The materials used in this invention are mainly multi-walled carbon nanotubes, 3-aminopropyltriethoxysilane, nano-iron oxide, cellulose nanofibers, methyltrimethoxysilane, ammonia, gum arabic, and glycerol.

[0037] Among them, multi-walled carbon nanotubes have a purity of ≥95%, an inner diameter of 5nm~12nm, an outer diameter of 30nm~50nm, a length of 20μm, and a specific surface area greater than 300m². 2 / g purchased from Shanghai Maclean Biochemical Technology Co., Ltd. 3-Aminopropyltriethoxysilane, purity 98%, purchased from Shanghai Maclean Biochemical Technology Co., Ltd., trade name / model is unknown. Nano-iron oxide, purity 99%, spherical with a diameter of 20nm, purchased from Shanghai Maclean Biochemical Technology Co., Ltd. Cellulose nanofibers, width 50nm, length up to several micrometers, purchased from Zhongshan Nanofiber New Material Co., Ltd. Methyltrimethoxysilane, purity 98%, purchased from Shanghai Maclean Biochemical Technology Co., Ltd. Ammonia water, concentration 25%~28%, purchased from Shanghai Maclean Biochemical Technology Co., Ltd. Gum arabic, purchased from Shanghai Maclean Biochemical Technology Co., Ltd. Glycerol, purity 99.7%, purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0038] Example 1 A method for preparing a photothermal ink includes the following steps: Preparation of aminated carbon nanotubes: 1.00 g of multi-walled carbon nanotubes were added to 50 mL of 0.6 mg / mL APTES ethanol solution, and the mixture was magnetically stirred at 40 °C and 800 rpm for 4 h. The mixture was washed 5 times with anhydrous ethanol and dried at 60 °C for 12 h to obtain NCNT powder.

[0039] Preparation of NCNT / Fe3O4: 1.00 g of NCNT and 0.80 g of nano Fe3O4 were added to 80 mL of anhydrous ethanol. The mixture was sonicated at 200 W for 30 min with intermittent sonication for 5 s and continuous sonication for 5 s. The mixture was stirred at 30 °C and 800 rpm for 2 h. The mixture was then centrifuged at 8000 rpm for 10 min. The mixture was washed three times with anhydrous ethanol and dried at 60 °C for 8 h to obtain NCNT / Fe3O4 composite powder.

[0040] Preparation of photothermal suspension: 40 mL of CNF suspension with 8 mg / mL and 40 mL of NCNT / Fe3O4 suspension with 8 mg / mL were mixed and sonicated at 200 W for 45 min. 0.80 mL of MTMS was added at 40 °C and stirred at 600 rpm for 6 h. 0.030 g of 25 wt% ammonia solution was added and reacted at 30 °C for 8 h to obtain the photothermal suspension.

[0041] Preparation of photothermal ink: 50 mL of photothermal suspension was mixed with 8.0 g of gum arabic and 12.0 g of glycerol in an oil bath at 70 °C, heated to 80 °C and stirred continuously for 4 h, and then cooled to room temperature to obtain photothermal ink.

[0042] Example 2 A method for preparing a photothermal ink includes the following steps: Preparation of aminated carbon nanotubes: 1.00 g of multi-walled carbon nanotubes were added to 50 mL of ethanol solution of 1 mg / mL APTES, and the mixture was magnetically stirred at 30 °C and 600 rpm for 4 h. The mixture was washed 5 times with anhydrous ethanol and dried at 60 °C for 12 h to obtain NCNT powder.

[0043] Preparation of NCNT / Fe3O4: 1.00 g of NCNT and 0.50 g of Fe3O4 were added to 80 mL of anhydrous ethanol. The mixture was sonicated at 200 W for 30 min with intermittent sonication for 5 s and continuous sonication for 5 s. The mixture was stirred at 30 °C and 600 rpm for 2 h. The mixture was then centrifuged at 8000 rpm for 10 min. The mixture was washed three times with anhydrous ethanol and dried at 60 °C for 8 h to obtain NCNT / Fe3O4 composite powder.

[0044] Preparation of photothermal suspension: 25 mL of CNF suspension with 5 mg / mL and 25 mL of NCNT / Fe3O4 suspension with 5 mg / mL were mixed and sonicated at 200 W for 45 min. 0.50 mL of MTMS was added at 25 °C and stirred at 600 rpm for 5 h. 0.010 g of 25 wt% ammonia solution was added and reacted at 30 °C for 4 h to obtain the photothermal suspension.

[0045] Preparation of photothermal ink: 40 mL of photothermal suspension was mixed with 5.0 g of gum arabic and 8.0 g of glycerol in an oil bath at 70 °C, heated to 80 °C and stirred continuously for 1 h, and then cooled to room temperature to obtain photothermal ink.

[0046] Example 3 A method for preparing a photothermal ink includes the following steps: Preparation of aminated carbon nanotubes: 1.00 g of multi-walled carbon nanotubes were added to 50 mL of 0.2 mg / mL APTES ethanol solution, and the mixture was magnetically stirred at 40 °C and 600 rpm for 4 h. The mixture was washed 5 times with anhydrous ethanol and dried at 60 °C for 12 h to obtain NCNT powder.

[0047] Preparation of NCNT / Fe3O4: 1.00 g of NCNT and 1.00 g of nano Fe3O4 were added to 80 mL of anhydrous ethanol. The mixture was sonicated at 200 W with 5 s intervals and 5 s continuous sonication for 30 min. The mixture was stirred at 30 °C and 600 rpm for 2 h. The mixture was then centrifuged at 8000 rpm for 10 min. The mixture was washed three times with anhydrous ethanol and dried at 60 °C for 8 h to obtain NCNT / Fe3O4 composite powder.

[0048] Preparation of photothermal suspension: 50 mL of CNF suspension with 10 mg / mL and 50 mL of NCNT / Fe3O4 suspension with 10 mg / mL were mixed and sonicated at 200 W for 45 min. 1.00 mL of MTMS was added at 25 °C and stirred at 600 rpm for 6 h. 0.050 g of 25 wt% ammonia solution was added and reacted at 30 °C for 10 h to obtain the photothermal suspension.

[0049] Preparation of photothermal ink: 100 mL of photothermal suspension was mixed with 10 g of gum arabic and 16.0 g of glycerol in an oil bath at 70 °C. The mixture was heated to 80 °C and stirred continuously for 5 h. After cooling to room temperature, the photothermal ink coating was obtained.

[0050] The photothermal ink prepared by this invention can be stably stored at room temperature for more than 30 days, exhibiting excellent photothermal conversion performance and good substrate adhesion, and showing a high viscosity at room temperature. Therefore, before using the ink, it should be placed in an 80°C water bath for 20 minutes and stirred at 500 rpm to restore dispersion and fluidity.

[0051] The photothermal inks prepared in Examples 1 to 3 of the present invention have similar properties. To further illustrate the beneficial effects of the present invention, the photothermal ink prepared in Example 1 of the present invention was used in the following application practice.

[0052] Application Example 1 Photothermal ink is coated onto the surface of a moisture-absorbing material to construct an evaporation layer structure with high photothermal conversion capability, which can be used for atmospheric moisture capture or water evaporation driven by solar energy.

[0053] (1) Preparation of the moisture-absorbing substrate A piece of delignified balsa wood with dimensions of 50mm×50mm×50mm was soaked in a 15wt% lithium chloride hygroscopic salt solution for 5 hours and then freeze-dried at 5pa pressure for 48 hours to obtain a wood-based hygroscopic composite material.

[0054] (2) Preparation and application of photothermal coating The photothermal ink prepared in Example 1 was dried at 80°C for 24 hours, and then uniformly coated onto one side of the wood-based moisture-absorbing composite material, with the coating thickness controlled at 124 μm. After coating, it was dried at 80°C for 6 hours to form a photothermal ink coating with complete structure and good adhesion.

[0055] (3) Performance characterization and results Wood-based moisture-absorbing composites coated with photothermal ink were used as the experimental group, and uncoated wood-based moisture-absorbing composites were used as the control group. The mixture was subjected to a 100mW / cm² temperature range. 2 Under standard AM1.5 illumination, photothermal conversion performance was tested, and the results are as follows: Figure 1 As shown in the figure. The results show that the wood-based moisture-absorbing composite material exhibits good interfacial bonding performance. The coating did not peel off or crack significantly during water evaporation. Infrared thermal imaging shows that the surface temperature of the wood-based moisture-absorbing composite material rises significantly. After 1 hour of light exposure, the surface temperature of the ink-coated sample rapidly increased from room temperature to 57°C, while the uncoated wood only increased to 38°C.

[0056] Application Example 2 (1) Substrate treatment Use balsa wood blocks measuring 50mm×50mm×50mm as the base material. Sand the wood surface with 400-grit sandpaper to remove rough fibers and dust, clean the surface with anhydrous ethanol, and dry it in a 60℃ constant temperature oven for 12 hours to remove moisture.

[0057] (2) Photothermal ink coating The photothermal ink prepared in Example 1 was uniformly coated onto one side of the balsa wood block, and the coating thickness was controlled to be 124 μm. After coating, the block was placed in a 60°C oven to dry for 6 hours.

[0058] Balsa wood blocks coated with photothermal ink were used as the experimental group, and balsa wood blocks without photothermal ink were used as the control group. The ink was applied at a temperature of 100 mW / cm². 2 The photothermal performance was tested after 10 minutes of irradiation under an AM1.5 solar simulator, and the results are as follows: Figure 2As shown in the figure. The results show that infrared thermal imaging revealed that the surface temperature of the balsa wood block coated with photothermal ink increased from room temperature to 87°C, while the surface temperature of the balsa wood block without photothermal ink coating only increased to 45°C, indicating that the photothermal ink coating of the present invention has significant photothermal conversion capability.

[0059] The coating morphology of photothermal ink on balsa wood blocks is as follows: Figure 3 As shown in the figure, the photothermal ink of the present invention can uniformly cover the surface of balsa wood blocks and partially penetrate into the inner wall of the ducts and the pore structure of the balsa wood blocks. Without completely blocking the pores, it achieves a tight bond between the coating and the surface of the balsa wood blocks, forming a stable interfacial transition layer. The resulting NCNT / Fe3O4 / CNF composite material is densely packed on the surface of the balsa wood blocks, constructing a continuous and complete film structure. No obvious cracks or peeling were observed in the overall coating, demonstrating excellent film-forming performance and structural stability. This structure not only helps to improve the durability and photothermal conversion efficiency of the coating, but also endows the balsa wood block base material with long-term stable photothermal response performance.

[0060] Microscopic morphology of balsa wood block cross-section after coating with photothermal ink, as shown Figure 4 As shown in the figure, microscopic observation results indicate that the photothermal ink can form a continuous and uniform coating on the surface of the balsa wood block, achieving good interfacial bonding with the balsa wood block substrate. Some ink penetrates into the ducts and fiber cavities of the balsa wood block surface, enhancing the mechanical interlocking between the coating and the balsa wood block, effectively improving the adhesion and structural stability of the photothermal layer. No obvious cracks, voids, or peeling were observed in the interfacial bonding area, indicating that the ink system has excellent film-forming properties and interfacial bonding quality, providing a structural basis for endowing the balsa wood block with long-term stable photothermal conversion capabilities.

[0061] The reflectance, transmittance, and absorptivity of the photothermal ink coating prepared in Example 1 are as follows: Figure 5 As shown in the figure. The results show that the multi-walled carbon nanotubes introduced into the photothermal ink have excellent thermal conductivity and broad-spectrum light absorption performance, which can significantly enhance the absorption and heat energy conversion capabilities of the composite photothermal layer for sunlight. When the photothermal ink is coated on the wood surface, it exhibits good spectral absorption performance in the wavelength range of 200nm~2500nm. The light absorption rate of the uncoated balsa wood block in the 280nm~2500nm range is only 32%, while after ink coating treatment, the average light absorption rate of the balsa wood block surface increases to 88.9%, the light reflectance decreases to below 15%, and the transmittance is almost zero, indicating that the photothermal coating achieves efficient light energy capture and transmission isolation throughout the entire solar spectrum. This performance significantly improves the solar thermal response capability of the balsa wood block surface, which helps to further enhance the photothermal conversion efficiency of its surface evaporation interface, providing key technical support for solar-driven water evaporation, energy harvesting, and functionalization applications of balsa wood blocks.

[0062] This invention enhances the dispersibility of multi-walled carbon nanotubes (MWCs) in polar systems and improves their interfacial bonding with siloxane networks and substrates by coupling MWCs with 3-aminopropyltriethoxysilane. Aminated MWCs are then composited with nano-Fe3O4 to form a line-point coupled broadband absorption and thermal conductivity network. MTMS and alkaline catalysis are introduced into a CNF aqueous suspension system to construct PMSQ adhesive bridges in situ, achieving uniform fixation of nano-components. A composite of gum arabic and glycerol is used as a film-forming plasticizer to obtain a coating that combines adhesion, flexibility, and density. This method is mild, simplified, and suitable for large-scale preparation. The resulting photothermal ink coating exhibits good light absorption in the UV-Vis-NIR band and maintains good adhesion and film uniformity on common porous substrates, making it suitable for applications such as solar-driven water harvesting, thermal management, and the construction of related functional surfaces.

[0063] This invention aims to improve the dispersibility and interfacial affinity of multi-walled carbon nanotubes by enhancing their ability to combine with other functional components through surface amylation modification. Simultaneously, the introduction of nano-Fe3O4 can enhance the photothermal synergistic effect, further improving the overall performance of the photothermal ink.

[0064] Although preferred embodiments of the present invention have been described, those skilled in the art, upon learning the inventive concept of the present invention, can make other changes and modifications to these embodiments, all of which fall within the scope of the present invention.

[0065] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. If such modifications and variations fall within the scope of equivalents of this invention, then this invention is also intended to include such modifications and variations.

Claims

1. A photothermal ink, characterized in that, The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 parts of gum arabic and 8-16 parts of glycerol; The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 parts of gum arabic and 8-16 parts of glycerol; The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 parts of gum arabic and 8-16 parts of glycerol; 2. The method for preparing a photothermal ink according to claim 1, characterized in that, The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 parts of gum arabic and 8-16 parts of glycerol; The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 parts of gum arabic and 8-16 parts of glycerol; The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 parts of gum arabic and 8-16 parts of glycerol; The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 parts of gum arabic and 8-16 parts of glycerol; The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 parts of gum arabic and 8-16 parts of glycerol; 3. The method of claim 2, wherein the photothermal ink is prepared by the steps of: The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 parts of gum arabic and 8-16 parts of glycerol; 4. The method for preparing a photothermal ink according to claim 2, characterized in that, The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 parts of gum arabic and 8-16 parts of glycerol; 5. The method for preparing a photothermal ink according to claim 2, characterized in that, The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 parts of gum arabic and 8-16 parts of glycerol; 6. The method of claim 2, wherein the photothermal ink is prepared by the steps of: The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 parts of gum arabic and 8-16 parts of glycerol; 7. The method for preparing a photothermal ink according to claim 2, characterized in that, The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 parts of gum arabic and 8-16 parts of glycerol; The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 parts of gum arabic and 8-16 parts of glycerol; The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 parts of gum arabic and 8-16 parts of glycerol; The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 parts of gum arabic and 8-16 parts of glycerol; 8. The method for preparing a photothermal ink according to claim 2, characterized in that, The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 parts of gum arabic and 8-16 parts of glycerol; The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 parts of gum arabic and 8-16 parts of glycerol; The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 parts of gum arabic and 8-16 parts of glycerol; The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 parts of gum arabic and 8-16 parts of glycerol; The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 parts of gum arabic and 8-16 parts of glycerol; The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 parts of gum arabic and 8-16 parts of glycerol; The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 parts of gum arabic and 8-16 parts of glycerol; The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 parts of gum arabic and 8-16 parts of glycerol; The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 parts of gum arabic and 8-16 parts of glycerol; The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 parts of gum arabic and 8-16 parts of glycerol; The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 parts of gum arabic and 8-16 parts of glycerol; The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 parts of gum arabic and 8-16 parts of glycerol; The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 parts of gum arabic and 8-16 parts of glycerol; The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 parts of gum arabic and 8-16 parts of glycerol; The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 parts of gum arabic and 8-16 parts of glycerol; The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 parts of gum arabic and 8-16 parts of glycerol; The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 parts of gum arabic and 8-16 parts of glycerol; The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 parts of gum arabic and 8-16 parts of glycerol; The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 parts of gum arabic and 8-16 parts of glycerol; The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 parts of gum arabic and 8-16 parts of glycerol; The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 parts of gum arabic and 8-16 parts of glycerol; The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 parts of gum arabic and 8-16 parts of glycerol; The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 parts of gum arabic and 8-16 parts of glycerol; The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 parts of gum arabic and 8-16 parts of glycerol; The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 parts of gum arabic and 8-16 parts of glycerol; The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 parts of gum arabic and 8-16 parts of glycerol; The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 parts of gum arabic and 8-16 parts of glycerol; The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 parts of gum arabic and 8-16 parts of glycerol; The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 parts of gum arabic and 8-16 parts of glycerol; The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 parts of gum arabic and 8-16 parts of glycerol; The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 parts of gum arabic and 8-16 parts of glycerol; The light-heat suspension is obtained by mixing and reacting 40-100 parts of the light-heat suspension, 5-10 The stirring reaction three conditions are that the temperature is 40℃, the stirring speed is 600rpm, and the reaction time is 6h. The stirring reaction four conditions are that the temperature is 40℃, the stirring speed is 600rpm, and the reaction time is 8h.

9. The method for preparing a photothermal ink according to claim 2, characterized in that, The weight ratio of the photothermal suspension, gum arabic and glycerol is 50:8:

12.

10. The use of the photothermal ink according to claim 1 in the preparation of a solar-driven atmospheric water harvesting and interfacial water evaporation product.

Images