A preparation method of a double-layer carbon-based photothermal material based on bisphenol a epoxy acrylate

Abstract

The application discloses a preparation method of a double-layer carbon-based photothermal material based on bisphenol A epoxy acrylate, and belongs to the technical field of photothermal distillation.The application aims at solving the problems of weak spectral absorption, poor hydrophilic performance, poor heat insulation effect, unstable forming, low pore forming precision and the like of the existing photocuring photosensitive resin, and the problems that the photocuring photosensitive resin cannot meet the preparation requirements of novel photothermal distillation materials.The preparation method comprises the following steps: one, carbon nanotube modification;two, preparation of a precursor solution;three, 3D printing preparation.The application is used for the preparation of the double-layer carbon-based photothermal material based on bisphenol A epoxy acrylate.

Description

Technical Field

[0001] This invention belongs to the field of photothermal distillation technology. Background Technology

[0002] Human-usable freshwater resources account for only 0.26% of the Earth's total water volume, and the lack of freshwater makes it impossible to guarantee people's basic living standards. Seawater desalination, as a technology for increasing water resource utilization, can increase the total amount of freshwater and is one of the effective ways to alleviate freshwater shortages. Traditional seawater desalination methods, such as electrodialysis and multi-stage flash distillation, have disadvantages such as high energy consumption, expensive equipment and materials, large greenhouse gas emissions, and significant environmental pollution. Compared with the former, which consumes a large amount of energy, solar thermal distillation technology has attracted widespread attention due to its advantages of not consuming conventional energy, being pollution-free, and producing high-purity freshwater. Therefore, using renewable, green, and clean solar energy for solar thermal distillation for seawater desalination has significant practical implications.

[0003] In photothermal distillation technology, interfacial evaporation materials, located above the water body, directly absorb solar heat without being weakened by the water, exhibiting a high evaporation rate and broad application prospects. Ideal photothermal materials should possess good light absorption capacity, hydrophilicity, thermal insulation performance, and salt suppression properties. Light absorption capacity allows the material to fully capture solar energy and convert it into heat to heat the water; hydrophilicity enhances capillary effects, enabling rapid water replenishment and ensuring a continuous water supply. Thermal insulation performance is crucial for better heat preservation, preventing heat loss from the material to the water body, which could lead to poor distillation results. During seawater desalination, salt deposits can cause pore blockage and reduce the effective light absorption area, affecting the evaporation rate of the material; therefore, the material also needs good salt suppression properties. Furthermore, the material's internal structure must be highly efficient and stable, acting as a bridge for water vapor transport, facilitating sufficient heating of the water and water vapor diffusion.

[0004] Hydrophilic-hydrophobic bilayer photothermal materials can form a relatively dense layer of water molecules at the interface, thereby preventing the interaction between salt and water molecules and achieving a good salt suppression effect. However, existing research still has shortcomings in the preparation of monolithic materials. In recent years, photopolymerization 3D printing technology has developed rapidly, and can now achieve micron-level precision. It also has advantages such as fast printing speed, good effect, high stability, and monolithic molding, and can be used to prepare monolithic bilayer photothermal evaporators with rich water vapor transport pore structures. However, existing photopolymerization photosensitive resins have weak spectral absorption, poor hydrophilicity, poor thermal insulation, unstable molding, and low pore formation precision, which cannot meet the preparation requirements of new photothermal distillation materials. Summary of the Invention

[0005] This invention aims to address the problems of existing photocurable photosensitive resins, such as weak spectral absorption, poor hydrophilicity, poor thermal insulation, unstable molding, and low pore formation precision, which fail to meet the requirements for preparing novel photothermal distillation materials. Therefore, it provides a method for preparing a bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate.

[0006] A method for preparing a bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate, characterized by the following steps:

[0007] I. Carbon nanotube modification:

[0008] ① Dissolve silane coupling agent KH-550 in an aqueous ethanol solution and hydrolyze to produce hydrophilic groups, resulting in a mixed solution;

[0009] ② Add carbon nanotubes to the mixed solution and sonicate, then react at a constant temperature of 70℃~80℃ for 2h~3h to obtain the reaction mixture;

[0010] ③ The mixture after reaction is subjected to solid-liquid separation, and then the solid is washed, dried and ground and sieved to obtain modified carbon nanotubes;

[0011] II. Preparation of precursor solution:

[0012] ① The modified carbon nanotubes were added to the bisphenol A epoxy acrylate photosensitive resin, and then the diluent and photoinitiator 819 were added and stirred evenly to obtain precursor solution 1;

[0013] The mass ratio of the modified carbon nanotubes to the bisphenol A epoxy acrylate photosensitive resin is 1:(61-72); the mass ratio of the modified carbon nanotubes to the diluent is 1:(261-272); and the mass ratio of the modified carbon nanotubes to the photoinitiator 819 is 1:(6-10).

[0014] ② Add unmodified carbon nanotubes to bisphenol A epoxy acrylate photosensitive resin, add diluent and photoinitiator 819 and stir evenly to obtain precursor solution 2;

[0015] The mass ratio of the unmodified carbon nanotubes to the bisphenol A epoxy acrylate photosensitive resin is 1:(61-72); the mass ratio of the unmodified carbon nanotubes to the diluent is 1:(261-272); and the mass ratio of the unmodified carbon nanotubes to the photoinitiator 819 is 1:(6-10).

[0016] III. 3D Printing Preparation:

[0017] ① Use simulation software to design the pore structure in photothermal materials, and then build the model;

[0018] ② Process the model using slicing software and add support structures, then import it into a photopolymerization 3D printing device;

[0019] ③ First, add precursor solution 1 for layer-by-layer 3D printing, then replace with precursor solution 2 and continue layer-by-layer 3D printing. After printing is completed, remove the support structure to obtain the photothermal material.

[0020] ④ The photothermal material is cleaned and cured with ultraviolet light in sequence to obtain a bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate.

[0021] The beneficial effects of this invention are:

[0022] (1) Based on the existing disordered microporous photothermal materials, this invention uses photopolymerization 3D printing technology to prepare the internal micropores of the photothermal material, and proposes a photothermal material preparation method based on photosensitive resin raw material - bisphenol A epoxy acrylate. This method not only realizes the water vapor transport channel required by the photothermal evaporator, but also realizes the good light absorption capacity, hydrophilicity, heat insulation capacity and salt suppression effect of the evaporation material.

[0023] (2) The present invention proposes a bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate, which exhibits good light absorption performance across the entire wavelength range, with an absorption rate better than 94%, of which the absorption rate in the visible light band can reach 95% to 96%.

[0024] (3) The present invention proposes a bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate. The hydrophilic layer prepared by the modified carbon nanotubes has a static water contact angle of 63°, while the non-hydrophilic photothermal material prepared by the unmodified carbon nanotubes has a static water contact angle of 78°. Compared with the latter, the water contact angle is significantly reduced, that is, the modification method improves the hydrophilicity.

[0025] (4) The present invention proposes a bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate, which achieves a performance of 1000 W / m 2 Under conditions of solar intensity, temperature of 26.8℃, and wind speed of 0.01m / s, the evaporation rate of pure water without the addition of photothermal materials is 0.204kg / m³. 2 The evaporation rate after adding the photothermal material prepared in Example 1 was 0.610 kg / m³. 2 •h, which is about 201% higher than that of pure water.

[0026] (5) The present invention proposes a bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate, which has a thermal conductivity coefficient of 0.191 W / (m·K), while the thermal insulation material has a thermal conductivity coefficient of 0.03 to 0.17 W / (m·K). Therefore, the carbon-based photothermal material based on bisphenol A epoxy acrylate can be regarded as a thermal insulation material. The thermal conductivity of the added carbon nanotube material is as high as 1000 W / (m·K) or more. It can be seen that although carbon nanotubes with high thermal conductivity are added, the material itself still maintains good thermal insulation performance, and plays the role of thermal insulation and heat preservation and avoids heat loss.

[0027] (6) The present invention proposes a bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate, which has high mechanical strength and stable properties.

[0028] (7) The present invention has good stability, good printing effect and high hole diameter accuracy during the printing process.

[0029] (8) The present invention proposes a bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate, which is low in cost, simple to operate, has high preparation quality, and is easy to mass-produce.

[0030] (9) The present invention proposes a bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate, wherein the upper layer is non-hydrophilic and the lower layer is hydrophilic. The lower layer has good hydrophilic properties and high surface energy, which can enable rapid replenishment of water vapor during evaporation. The non-hydrophilic material used in the upper layer can form a hydrophilic-hydrophobic structure with it, preventing the interaction between salt and water molecules, reducing the dissolution of salt, and thus achieving a good salt inhibition effect.

[0031] (10) The present invention proposes a double-layer carbon-based photothermal material based on bisphenol A epoxy acrylate, which has good joint at the double layer connection and no discontinuity or warping.

[0032] Instruction manual illustrations

[0033] Figure 1 This is a static water contact angle diagram of the non-hydrophilic layer after 3D printing using precursor solution 2 in step 3③ of Example 1.

[0034] Figure 2 This is a static water contact angle diagram of the hydrophilic layer after 3D printing using precursor solution 1 in step 3③ of Example 1.

[0035] Figure 3 The image shows the pore size of the bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate prepared in Example 1.

[0036] Figure 4 The image shows a scanning electron microscope (SEM) image of the surface morphology of the bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate prepared in Example 1.

[0037] Figure 5 The full-spectral absorption spectrum of the bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate prepared in Example 1 is shown.

[0038] Figure 6 The graphs are for evaporation performance testing. 1 shows the evaporation performance of the bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate prepared in Example 1, and 2 shows the evaporation performance of pure water without photothermal material.

[0039] Figure 7 The mechanical strength test diagrams of the bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate prepared in Example 1 are shown in the following diagrams: a) the material is suspended on two iron blocks; b) two 200g weights are applied to the surface of the material; c) the surface of the material after the weights are removed.

[0040] Figure 8 The images show infrared thermal images of the evaporation experiment of the bisphenol A epoxy acrylate-based bilayer carbon-based photothermal material prepared in Example 1, with and without being placed in water. a is with the material in water, and b is without being placed in water.

[0041] Figure 9 The image shows a cross-sectional view of the connection point of the bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate prepared in Example 1. a is a physical image, and b is a scanning electron microscope image. Detailed Implementation

[0042] Specific Implementation Method 1: This implementation method describes a method for preparing a bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate, which is carried out according to the following steps:

[0043] I. Carbon nanotube modification:

[0044] ① Dissolve silane coupling agent KH-550 in an aqueous ethanol solution and hydrolyze to produce hydrophilic groups, resulting in a mixed solution;

[0045] ② Add carbon nanotubes to the mixed solution and sonicate, then react at a constant temperature of 70℃~80℃ for 2h~3h to obtain the reaction mixture;

[0046] ③ The mixture after reaction is subjected to solid-liquid separation, and then the solid is washed, dried and ground and sieved to obtain modified carbon nanotubes;

[0047] II. Preparation of precursor solution:

[0048] ① The modified carbon nanotubes were added to the bisphenol A epoxy acrylate photosensitive resin, and then the diluent and photoinitiator 819 were added and stirred evenly to obtain precursor solution 1;

[0049] The mass ratio of the modified carbon nanotubes to the bisphenol A epoxy acrylate photosensitive resin is 1:(61-72); the mass ratio of the modified carbon nanotubes to the diluent is 1:(261-272); and the mass ratio of the modified carbon nanotubes to the photoinitiator 819 is 1:(6-10).

[0050] ② Add unmodified carbon nanotubes to bisphenol A epoxy acrylate photosensitive resin, add diluent and photoinitiator 819 and stir evenly to obtain precursor solution 2;

[0051] The mass ratio of the unmodified carbon nanotubes to the bisphenol A epoxy acrylate photosensitive resin is 1:(61-72); the mass ratio of the unmodified carbon nanotubes to the diluent is 1:(261-272); and the mass ratio of the unmodified carbon nanotubes to the photoinitiator 819 is 1:(6-10).

[0052] III. 3D Printing Preparation:

[0053] ① Use simulation software to design the pore structure in photothermal materials, and then build the model;

[0054] ② Process the model using slicing software and add support structures, then import it into a photopolymerization 3D printing device;

[0055] ③ First, add precursor solution 1 for layer-by-layer 3D printing, then replace with precursor solution 2 and continue layer-by-layer 3D printing. After printing is completed, remove the support structure to obtain the photothermal material.

[0056] ④ The photothermal material is cleaned and cured with ultraviolet light in sequence to obtain a bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate.

[0057] The hydrophilic groups mentioned in step 1① of this embodiment are amino and hydroxyl groups, etc.

[0058] The unmodified carbon nanotubes mentioned in step 2② of this embodiment are the same carbon nanotube raw materials mentioned in step 1②.

[0059] The beneficial effects of this embodiment are:

[0060] (1) Based on the existing disordered microporous photothermal materials, this embodiment uses photopolymerization 3D printing technology to prepare the internal micropores of the photothermal material, and proposes a photothermal material preparation method based on photosensitive resin raw material - bisphenol A epoxy acrylate. This method not only realizes the water vapor transport channel required by the photothermal evaporator, but also realizes the good light absorption capacity, hydrophilicity, heat insulation capacity and salt suppression effect of the evaporation material.

[0061] (2) The bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate proposed in this embodiment exhibits good light absorption performance across the entire wavelength range, with an absorption rate better than 94%, of which the absorption rate in the visible light band can reach 95% to 96%.

[0062] (3) The bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate proposed in this embodiment has a static water contact angle of 63° for the hydrophilic layer made by modified carbon nanotubes and a static water contact angle of 78° for the non-hydrophilic photothermal material made by unmodified carbon nanotubes. The water contact angle is significantly reduced compared to the latter, that is, the modification method improves the hydrophilicity.

[0063] (4) The bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate proposed in this embodiment achieves a performance of 1000 W / m 2 Under conditions of solar intensity, temperature of 26.8℃, and wind speed of 0.01m / s, the evaporation rate of pure water without the addition of photothermal materials is 0.204kg / m³. 2 The evaporation rate after adding the photothermal material prepared in Example 1 was 0.610 kg / m³. 2 •h, which is about 201% higher than that of pure water.

[0064] (5) The bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate proposed in this embodiment has a thermal conductivity coefficient of 0.191 W / (m·K), while that of the insulation material is 0.03 to 0.17 W / (m·K). Therefore, the carbon-based photothermal material based on bisphenol A epoxy acrylate can be regarded as an insulation material. The thermal conductivity of the added carbon nanotube material is as high as 1000 W / (m·K). It can be seen that although carbon nanotubes with high thermal conductivity are added, the material itself still maintains good thermal insulation performance, and plays the role of heat insulation and heat preservation and avoids heat loss.

[0065] (6) The bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate proposed in this embodiment has high mechanical strength and stable properties.

[0066] (7) This embodiment has good stability, good printing effect and high hole accuracy during the printing process.

[0067] (8) The bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate proposed in this embodiment is low in cost, simple to operate, has high preparation quality, and is easy to mass-produce.

[0068] (9) The bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate proposed in this embodiment has an upper non-hydrophilic layer and a lower hydrophilic layer. The lower layer has good hydrophilic properties and high surface energy, which can realize the rapid replenishment of water vapor during evaporation. The non-hydrophilic material used in the upper layer can form a hydrophilic-hydrophobic structure with it, prevent the interaction between salt and water molecules, reduce the dissolution of salt, and thus play a good salt inhibition effect.

[0069] (10) The double-layer carbon-based photothermal material based on bisphenol A epoxy acrylate proposed in this embodiment has good joint at the double-layer connection, with no discontinuity or warping.

[0070] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that: in step one ①, under conditions of 40℃~60℃, the silane coupling agent KH-550 is dissolved in an ethanol-water solution and hydrolyzed for 3h~5h to generate hydrophilic groups; the volume ratio of ethanol to water in the ethanol-water solution is 1:(0.06~0.3); the mass ratio of the silane coupling agent KH-550 to the volume ratio of the ethanol-water solution is 1g:(6~8)mL. Everything else is the same as in Specific Implementation Method One.

[0071] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that: the carbon nanotubes mentioned in step one ② and the unmodified carbon nanotubes mentioned in step two ② are both multi-walled carbon nanotubes with an inner diameter of 3nm to 5nm, an outer diameter of 8nm to 15nm, and a particle size of less than 7μm; the ultrasonic treatment mentioned in step one ② is specifically performed at a power of 200W to 300W for 2h to 3h. Everything else is the same as in Specific Implementation Method One or Two.

[0072] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that: in step one ③, anhydrous ethanol is used to wash the solid, followed by drying at 100℃~150℃ for 3h~5h, and finally grinding and sieving through a 2000-5000 mesh sieve. Everything else is the same as in Specific Implementation Methods One to Three.

[0073] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that the diluent mentioned in steps 2① and ② is tripropylene glycol diacrylate. Everything else is the same as in Specific Implementation Methods One to Four.

[0074] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that: in step three①, the pore structure of the photothermal material is designed as vertically connected channels, and the channels are arranged in a quadrilateral array, with a center-to-center distance of 1.3mm to 1.6mm between adjacent channels. Everything else is the same as in Specific Implementation Methods One to Five.

[0075] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that the cross-section of the pore structure in the photothermal material designed in step three① is circular. Everything else is the same as in Specific Implementation Methods One to Six.

[0076] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in that the diameter of the pores in the photothermal material designed in step three① is 500μm to 750μm. Everything else is the same as in Specific Implementation Methods One to Seven.

[0077] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that: the 3D printing described in step three ③ is specifically performed layer-by-layer 3D printing under the following conditions: lifting speed of 55mm / min to 65mm / min, return speed of 145mm / min to 155mm / min, ultraviolet power of 180W to 220W, and ultraviolet wavelength of 355nm to 405nm. During the printing process, the exposure time for the bottom layer is 28s to 30s, and the exposure time for a single layer is 4.5s to 5.5s. The thickness of each layer printed in step three ③ is 0.02mm to 0.05mm. The ratio of the number of layers printed using precursor solution 1 to the number of layers printed using precursor solution 2 in step three ③ is (3 to 4):1. Everything else is the same as in Specific Implementation Methods One to Eight.

[0078] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods One to Nine in that the ultraviolet curing described in step three, fourth, is specifically performed under ultraviolet light conditions with a power of 80W to 120W and a wavelength of 355nm to 405nm, with multiple curing operations at different angles, and a total curing time of 20min to 30min. Everything else is the same as in Specific Implementation Methods One to Nine.

[0079] The beneficial effects of the present invention are verified using the following embodiments:

[0080] Example 1:

[0081] A method for preparing a bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate, comprising the following steps:

[0082] I. Carbon nanotube modification:

[0083] ① At a temperature of 60℃, 30g of silane coupling agent KH-550 was dissolved in 180mL of ethanol aqueous solution and hydrolyzed for 3h to produce hydrophilic groups, resulting in a mixed solution;

[0084] The volume ratio of ethanol to water in the ethanol-water solution is 1:0.06;

[0085] ② Add carbon nanotubes to the mixed solution, sonicate for 3 hours at a power of 240W, and then react at a constant temperature of 70℃ for 2 hours to obtain the reaction mixture.

[0086] ③ The reaction mixture was separated into solid and liquid by filtration. The solid was then washed with anhydrous ethanol to remove residual silane coupling agent. The mixture was then dried at 100°C for 3 hours. Finally, it was ground and sieved through a 2000-mesh sieve to obtain modified carbon nanotubes.

[0087] II. Preparation of precursor solution:

[0088] ① The modified carbon nanotubes were added to the bisphenol A epoxy acrylate photosensitive resin, and then a diluent and photoinitiator 819 were added. The mixture was magnetically stirred for 20 minutes at a speed of 1800 r / min to obtain precursor solution 1.

[0089] The mass ratio of the modified carbon nanotubes, bisphenol A epoxy acrylate photosensitive resin, diluent, and photoinitiator 819 is 3:200:800:20.

[0090] ② Add unmodified carbon nanotubes to bisphenol A epoxy acrylate photosensitive resin, then add diluent and photoinitiator 819, and stir magnetically for 20 minutes at a speed of 1800 r / min to obtain precursor solution 2.

[0091] The mass ratio of the unmodified carbon nanotubes, bisphenol A epoxy acrylate photosensitive resin, diluent, and photoinitiator 819 is 3:200:800:20.

[0092] III. 3D Printing Preparation:

[0093] ① Use the simulation software COMSOL to design the pore structure in the photothermal material, and then use the modeling software SOLIDWORKS to build the model;

[0094] ② The model is processed using the slicing software CHITUBOX and a support structure is added, and then imported into the photopolymer 3D printing equipment;

[0095] ③ First, add precursor solution 1 for layer-by-layer 3D printing, then replace with precursor solution 2 and continue layer-by-layer 3D printing. After printing is completed, remove the support structure to obtain the photothermal material.

[0096] ④ The photothermal material is cleaned and cured with ultraviolet light in sequence to obtain a bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate.

[0097] The carbon nanotubes mentioned in step 1② and the unmodified carbon nanotubes mentioned in step 2② are both multi-walled carbon nanotubes with a purity of 95%, an inner diameter of 3nm to 5nm, an outer diameter of 8nm to 15nm, and a particle size of less than 7μm.

[0098] The diluent mentioned in steps ① and ② is tripropylene glycol diacrylate.

[0099] In step 3①, the photothermal material is designed as a circular plate with a thickness of 3mm and a diameter of 41mm.

[0100] In step 3①, the pore structure of the photothermal material is designed as a vertical channel that is connected from top to bottom, and the pores are arranged in a quadrilateral array with a center-to-center distance of 1.3mm between adjacent pores.

[0101] In step 3①, the cross-section of the pore structure in the photothermal material is circular with a diameter of 500μm.

[0102] Step 3 ② Set a straight column support structure on the bottom surface of the photothermal material, and the angle between the straight column support structure and the plate surface of the photothermal material is 90°;

[0103] The 3D printing described in step 3③ is specifically carried out layer by layer under the conditions of a lifting speed of 60mm / min, a return speed of 150mm / min, an ultraviolet power of 200W, and an ultraviolet wavelength of 405nm. During the printing process, the exposure time of the bottom layer is 28s, and the exposure time of each layer is 5 seconds. The thickness of each layer printed in step 3③ is 0.05mm. The ratio of the number of layers printed using precursor solution 1 to the number of layers printed using precursor solution 2 in step 3③ is 3:1.

[0104] The ultraviolet curing described in step 3③ specifically involves curing both sides under ultraviolet light conditions with a power of 100W and a wavelength of 405nm, and a total curing time of 30min.

[0105] The structural formula of the bisphenol A epoxy acrylate photosensitive resin described in steps ① and ② is shown in formula (Ⅰ):

[0106]

[0107] The diluent mentioned in steps ① and ② is tripropylene glycol diacrylate (TPGDA), with the structural formula shown in formula (II):

[0108]

[0109] The photoinitiator 819 mentioned in steps ① and ② is phenylphosphine dioxide (2,4,6-trimethylbenzoylphosphine dioxide), with the structural formula shown in formula (Ⅲ):

[0110]

[0111] Step 3 ③ After 3D printing using precursor solution 2, a non-hydrophilic layer is obtained; after 3D printing using precursor solution 1, a hydrophilic layer is obtained.

[0112] Example 2: This example differs from Example 1 in that the diameter of the channel in step 3① is 550μm. Everything else is the same as in Example 1.

[0113] Example 3: This example differs from Example 1 in that the diameter of the channel in step 3① is 600μm. Everything else is the same as in Example 1.

[0114] Example 4: This example differs from Example 1 in that the diameter of the channel in step 3① is 750μm. Everything else is the same as in Example 1.

[0115] Comparative Experiment 1: This comparative experiment differs from Example 1 in that the mixture after solid-liquid separation in step 1③ was not washed and dried, and silane coupling agent residue remained. Everything else is the same as in Example 1.

[0116] Comparative Experiment 2: This embodiment differs from Embodiment 1 in that the angle between the straight column support structure and the surface of the photothermal material in step 3② is 20°. Everything else is the same as in Embodiment 1.

[0117] Comparative Experiment 3: The difference between this embodiment and Embodiment 1 is that the single-layer exposure time in step 3② is 2 seconds. Everything else is the same as in Embodiment 1.

[0118] Comparative Experiment 4: The difference between this example and Example 1 is that the single-layer exposure time in step 3② is 4s. Everything else is the same as in Example 1.

[0119] Comparative Experiment 5: This embodiment differs from Embodiment 1 in that: the mass ratio of modified carbon nanotubes:bisphenol A epoxy acrylate photosensitive resin:diluent:photoinitiator 819 in step 2① is 3:200:1000:20; the mass ratio of unmodified carbon nanotubes:bisphenol A epoxy acrylate photosensitive resin:diluent:photoinitiator 819 in step 2② is 3:200:1000:20. Everything else is the same as in Embodiment 1.

[0120] Comparative Experiment Six: This example differs from Example One in that the mass ratio of modified carbon nanotubes:bisphenol A epoxy acrylate photosensitive resin:diluent:photoinitiator 819 in step two ① is 7:200:800:20; while the mass ratio of unmodified carbon nanotubes:bisphenol A epoxy acrylate photosensitive resin:diluent:photoinitiator 819 in step two ② is 7:200:800:20. Everything else is the same as in Example One.

[0121] Figure 1The static water contact angle diagram of the non-hydrophilic layer after 3D printing using precursor solution 2 in step 3③ of Example 1 is shown. As can be seen from the figure, the added carbon nanotube particles were not modified by silane coupling agent KH-550, and the static water contact angle was 78°.

[0122] Figure 2 The figure shows the static water contact angle of the hydrophilic layer after 3D printing using precursor solution 1 in step 3③ of Example 1. As can be seen from the figure, the static water contact angle of the hydrophilic layer in the prepared bilayer photothermal material is 63°, which is significantly smaller than the water contact angle of the non-hydrophilic layer prepared using unmodified carbon nanotubes. That is, the hydrophilicity of the material is significantly improved after modification.

[0123] Figure 3 The image shows a scanning electron microscope (SEM) image of the pore size of the bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate prepared in Example 1. As can be seen from the image, the pore diameter measured by the SEM scale is 499.79 μm, which is 0.04% different from the designed size of 500 μm. Therefore, it can be seen that the prepared photothermal material has good pore size formation effect and high forming accuracy.

[0124] Figure 4 The image shows a scanning electron microscope (SEM) image of the surface morphology of the bisphenol A epoxy acrylate-based bilayer carbon-based photothermal material prepared in Example 1. As can be seen from the image, the surface of the prepared photothermal material exhibits rough protrusions of varying sizes at an extremely fine scale, which enhances diffuse light reflection and improves light utilization. Furthermore, the pore spacing measured by the SEM scale is 1.30 mm, which meets the design requirements, indicating good forming effect and high precision.

[0125] Figure 5 The image shows the full-spectrum absorption spectrum of the bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate prepared in Example 1. As can be seen from the image, the prepared photothermal material exhibits good light absorption performance in both the visible and infrared bands. The absorption rate for visible light with wavelengths of 380 nm to 780 nm is 95% to 96%, and the absorption rate for infrared light with wavelengths of 2 to 4 μm is 94% to 95%.

[0126] The bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate prepared in Example 1 has a non-hydrophilic upper layer and a hydrophilic lower layer. The lower layer has good hydrophilic properties and high surface energy, which can enable rapid replenishment of water vapor during evaporation. The non-hydrophilic material used in the upper layer can form a hydrophilic-hydrophobic structure with it, preventing the interaction between salt and water molecules, reducing salt dissolution, and thus achieving a good salt inhibition effect.

[0127] Figure 6 The graph shows the evaporation performance test curves. 1 represents the evaporation performance of the bisphenol A epoxy acrylate-based bilayer carbon-based photothermal material prepared in Example 1, and 2 represents the evaporation performance of pure water without the photothermal material. (The graph is at 1000 W / m².)2 Under conditions of solar intensity, temperature of 26.8℃, and wind speed of 0.01m / s, the evaporation rate of pure water without the addition of photothermal materials is 0.204kg / m³. 2 The evaporation rate after adding photothermal material is 0.610 kg / m³. 2 •h, which is about 201% higher than that of pure water.

[0128] Figure 7 The mechanical strength test diagrams for the bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate prepared in Example 1 are shown in Figure a. The material is suspended above two iron blocks. Figure b shows the material surface after two 200g weights are applied. Figure c shows the material surface after the weights are removed. As can be seen from the figures, when the material is suspended above two iron blocks and two 200g weights are applied, no breakage, damage, or fracture is observed. No cracking or deformation is observed when the material is removed, proving that it has good mechanical strength and good compressive strength.

[0129] Figure 8 Infrared thermal images of the evaporation experiment of the bisphenol A epoxy acrylate-based bilayer carbon-based photothermal material prepared in Example 1, placed in water or not. a) shows the material placed in water, and b) shows the material not placed in water. As can be seen from the images, at 1000 W / m... 2 Under conditions of solar intensity, temperature of 26.8℃, and wind speed of 0.01m / s, the highest surface temperature of the material when placed in water is approximately 58.4℃, while the water temperature is 23.4℃. In contrast, the highest surface temperature of the material not placed in water reaches 75.2℃. This means that even with water present and heat conduction occurring, the difference in the highest surface temperatures of the two materials is only 16.8℃, and the material maintains a relatively large temperature difference of 35℃ with the water. This indirectly verifies that the material itself has a low thermal conductivity, i.e., strong heat insulation capability.

[0130] Figure 9 The figures show cross-sectional views of the joint of the bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate prepared in Example 1. Figure a is a physical image, and figure b is a scanning electron microscope (SEM) image. As can be seen from the figures, the prepared material shows no visible discontinuity or warping at the joint, indicating a good connection. Furthermore, measurements of the slit formed by the bonding of the two layers under high-magnification SEM imaging show that the slit width is approximately 80 μm, which is within the micrometer scale and has negligible impact on the material itself and the experiment. The connection quality is high, and the forming effect is excellent. In summary, the bilayer material prepared in Example 1 exhibits good connection quality, high bonding quality, and good forming at the joint.

[0131] The bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate prepared in Example 1 was tested using a Hotdisk TPS2500 thermal constant analyzer at a temperature of 28°C and a reference standard of ISO 22007. The thermal conductivity coefficient was measured to be 0.191 W / (m·K). Compared with the thermal insulation materials, which have a thermal conductivity of 0.03 to 0.17 W / (m·K), this material can be considered almost as a thermal insulation material. The thermal conductivity of the added carbon nanotube material is as high as 1000 W / (m·K) or more. It can be seen that despite the addition of carbon nanotubes with high thermal conductivity, the material itself still maintains good thermal insulation performance.

[0132] Example 2 shows a bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate, which is used at 1000 W / m. 2 Under conditions of solar intensity, temperature of 26.8℃, and wind speed of 0.01m / s, the evaporation rate after adding photothermal material is 0.605kg / m³. 2 •h, which is about 197% higher than that of pure water.

[0133] Example 3 describes a bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate, prepared at 1000 W / m. 2 Under conditions of solar intensity, temperature of 26.8℃, and wind speed of 0.01m / s, the evaporation rate after adding photothermal material is 0.595kg / m³. 2 •h, which is about 192% higher than that of pure water.

[0134] Example 4 describes a bilayer carbon-based photothermal material prepared using bisphenol A epoxy acrylate at 1000 W / m. 2 Under conditions of solar intensity, temperature of 26.8℃, and wind speed of 0.01m / s, the evaporation rate after adding photothermal material is 0.578kg / m³. 2 •h, which is about 183% higher than that of pure water.

[0135] Compared with the bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate prepared in Experiment 1, the modified carbon nanotubes were not washed and dried. The residual silane coupling agent reacted with the bisphenol A epoxy acrylate, which enhanced the adhesion of the precursor solution and made it into a viscous gel. This resulted in poor photopolymerization 3D printing effect and the overall material did not form.

[0136] Compared with the bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate prepared in Experiment 2, the support addition angle was changed to 20°. Due to insufficient support force, the support broke, the photothermal material did not form, and the release film consumables were damaged during the photopolymerization 3D printing process, resulting in material preparation failure. Moreover, this support angle is not conducive to the formation of bilayer structure.

[0137] Compared with the bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate prepared in Experiment 3, the single-layer exposure time was 2s. Due to the insufficient exposure time, the pore size formation effect was poor, and phenomena such as poor layer-by-layer connection of photothermal material, material collapse and non-formation, and photothermal material falling off the printing platform were observed.

[0138] Compared with the bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate prepared in Experiment 4, the single-layer exposure time was 4s. Due to the excessive exposure time, the pore formation effect was poor, the pore size was too small, and pore blockage, failure to form pores, large errors, and difficulty in removing the support were all observed.

[0139] Compared with the bilayer carbon-based photothermal material prepared by bisphenol A epoxy acrylate in Experiment 5, the material did not form well because the amount of diluent added was too large, resulting in too little resin monomer content in the precursor solution.

[0140] Compared with the bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate prepared in Experiment 6, the excessive addition of carbon nanotubes resulted in insufficient absorption of ultraviolet light by the resin monomers in the precursor solution, incomplete curing, material failure to form, and excessive brittleness with insufficient mechanical strength.

Claims

1. A method for preparing a bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate, characterized in that... It is done in the following steps: I. Carbon nanotube modification: ① Dissolve silane coupling agent KH-550 in an aqueous ethanol solution and hydrolyze to produce hydrophilic groups, resulting in a mixed solution; ② Add carbon nanotubes to the mixed solution and sonicate, then react at a constant temperature of 70℃~80℃ for 2h~3h to obtain the reaction mixture; ③ The mixture after reaction is subjected to solid-liquid separation, and then the solid is washed, dried and ground and sieved to obtain modified carbon nanotubes; II. Preparation of precursor solution: ① The modified carbon nanotubes were added to the bisphenol A epoxy acrylate photosensitive resin, and then the diluent and photoinitiator 819 were added and stirred evenly to obtain precursor solution 1; The mass ratio of the modified carbon nanotubes to the bisphenol A epoxy acrylate photosensitive resin is 1:(61-72); the mass ratio of the modified carbon nanotubes to the diluent is 1:(261-272); and the mass ratio of the modified carbon nanotubes to the photoinitiator 819 is 1:(6-10). ② Add unmodified carbon nanotubes to bisphenol A epoxy acrylate photosensitive resin, add diluent and photoinitiator 819 and stir evenly to obtain precursor solution 2; The mass ratio of the unmodified carbon nanotubes to the bisphenol A epoxy acrylate photosensitive resin is 1:(61-72); the mass ratio of the unmodified carbon nanotubes to the diluent is 1:(261-272); and the mass ratio of the unmodified carbon nanotubes to the photoinitiator 819 is 1:(6-10). III. 3D Printing Preparation: ① Use simulation software to design the pore structure in photothermal materials, and then build the model; ② Process the model using slicing software and add support structures, then import it into a photopolymer 3D printing device; ③ First, add precursor solution 1 for layer-by-layer 3D printing, then replace with precursor solution 2 and continue layer-by-layer 3D printing. After printing is completed, remove the support structure to obtain the photothermal material. ④ The photothermal material is cleaned and cured with ultraviolet light in sequence to obtain a bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate.

2. The method for preparing a bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate according to claim 1, characterized in that... In step 1①, under the condition of 40℃~60℃, the silane coupling agent KH-550 is dissolved in an ethanol aqueous solution and hydrolyzed for 3h~5h to generate hydrophilic groups; the volume ratio of ethanol to water in the ethanol aqueous solution is 1:(0.06~0.3); the mass ratio of the silane coupling agent KH-550 to the volume ratio of the ethanol aqueous solution is 1g:(6~8)mL.

3. The method for preparing a bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate according to claim 1, characterized in that... The carbon nanotubes mentioned in step 1② and the unmodified carbon nanotubes mentioned in step 2② are both multi-walled carbon nanotubes with an inner diameter of 3nm to 5nm, an outer diameter of 8nm to 15nm, and a particle size of less than 7μm. The ultrasonic treatment mentioned in step 1② is specifically performed under the condition of 200W to 300W power for 2h to 3h.

4. The method for preparing a bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate according to claim 1, characterized in that... In step 1③, the solid is washed with anhydrous ethanol, then dried at 100℃~150℃ for 3h~5h, and finally ground and sieved through a 2000-5000 mesh sieve.

5. The method for preparing a bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate according to claim 1, characterized in that... The diluent mentioned in steps ① and ② is tripropylene glycol diacrylate.

6. The method for preparing a bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate according to claim 1, characterized in that... In step 3①, the pore structure of the photothermal material is designed as a vertical channel that is connected from top to bottom, and the pores are arranged in a quadrilateral array with a center-to-center distance of 1.3mm to 1.6mm between adjacent pores.

7. The method for preparing a bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate according to claim 6, characterized in that... In step 3①, the cross-section of the pore structure in the photothermal material is designed to be circular.

8. The method for preparing a bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate according to claim 7, characterized in that... In step 3①, the diameter of the pores in the photothermal material is designed to be 500μm~750μm.

9. The method for preparing a bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate according to claim 1, characterized in that... The 3D printing described in step 3③ is specifically carried out layer by layer under the following conditions: lifting speed of 55mm / min~65mm / min, return speed of 145mm / min~155mm / min, ultraviolet power of 180W~220W, and ultraviolet wavelength of 355nm~405nm. During the printing process, the exposure time of the bottom layer is 28s~30s, and the exposure time of a single layer is 4.5s~5.5s. The thickness of each layer printed in step 3③ is 0.02mm~0.05mm. The ratio of the number of layers printed using precursor solution 1 to the number of layers printed using precursor solution 2 in step 3③ is (3~4):

1.

10. The method for preparing a bilayer carbon-based photothermal material based on bisphenol A epoxy acrylate according to claim 1, characterized in that... The ultraviolet curing described in step three and four specifically involves curing at different angles multiple times under ultraviolet light conditions with a power of 80W to 120W and a wavelength of 355nm to 405nm, with a total curing time of 20min to 30min.

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