3D-printed temperature-responsive hydrogel evaporator and method of making the same

Abstract

The embodiment of the application provides a 3D printing hydrogel evaporator with temperature response and a preparation method thereof, and belongs to the technical field of seawater desalination.The 3D printing hydrogel evaporator comprises: an upper layer of the evaporator, which is a photothermal response layer, and the photothermal response layer comprises N-isopropyl acrylamide as a temperature-sensitive polymer; a lower layer of the evaporator, which is a hydrophilic layer configured to provide moisture for the upper layer of the evaporator, wherein the upper layer of the evaporator and the lower layer of the evaporator are adjusted in spatial structure through a 3D printing technology and integrally cured and formed.The 3D printing hydrogel evaporator prepared by the application has excellent photothermal conversion performance and water evaporation efficiency, the electrolyte property of sodium alginate and the Marangoni effect caused by the spatial structure of the internal design of the device, so that the device has super-high salt rejection performance, and is suitable for seawater desalination, sewage treatment and other applications.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of seawater evaporation devices, and relates to a 3D-printed gel evaporator with temperature response and a preparation method thereof. BACKGROUND

[0002] Distillation to obtain fresh water is an energy-intensive process, and sunlight under natural conditions is difficult to meet the energy demand of water evaporation. The water gel evaporator reduces the evaporation enthalpy of water by changing the interaction between the polymer and water molecules, thereby avoiding insufficient supply of solar energy.

[0003] However, the traditional water gel evaporator has a simple structure, and the water transportation in the device is limited by the microporous structure inside the gel itself. Long-term use is prone to pollution, especially salt accumulation, which seriously hinders the flow of liquid, causing low evaporation efficiency or serious problems of evaporation rate reduction.

[0004] In order to fully utilize light energy, improve light-heat conversion rate, and enhance water evaporation efficiency and salt resistance, it is of great significance to develop a gel device with high salt resistance and high water evaporation efficiency. SUMMARY

[0005] The present application aims to at least partially solve the above technical problems, and aims to provide a 3D-printed gel evaporator with temperature response and a preparation method thereof. The 3D-printed water gel evaporator prepared by the present application has excellent light-heat conversion performance and water evaporation efficiency. The electrolyte properties of sodium alginate and the Marangoni effect caused by the spatial structure designed in the device make the device have ultra-high salt removal performance, and the device is suitable for seawater desalination, sewage treatment and other applications.

[0006] In one aspect of the present application, a 3D-printed water gel evaporator with temperature response is provided, which comprises:

[0007] an upper layer of the evaporator, which is a photothermal response layer, the photothermal response layer comprising N-isopropyl acrylamide as a temperature-sensitive polymer;

[0008] a lower layer of the evaporator, which is a hydrophilic layer configured to provide moisture to the upper layer of the evaporator,

[0009] wherein the upper layer of the evaporator and the lower layer of the evaporator are adjusted in spatial structure by 3D printing technology and integrally cured and formed.

[0010] In some embodiments, the integrally cured and formed is performed by a calcium chloride solution.

[0011] In some embodiments, the N-isopropyl acrylamide has a molecular conformation transition above the lower critical solution temperature, from hydrophilic to hydrophobic, and the molecular chain of the N-isopropyl acrylamide changes from extended to collapsed to expel water.

[0012] In some embodiments, the upper layer of the evaporator and the lower layer of the evaporator are arranged as a porous staggered cross structure.

[0013] In some embodiments, the upper layer of the evaporator comprises a plurality of super-hydrophilic functional sub-layers prepared by 3D printing technology, each super-hydrophilic functional sub-layer comprising a plurality of first elongated gel cylinders arranged at intervals.

[0014] The lower layer of the evaporator comprises a plurality of super-hydrophilic functional sub-layers prepared by 3D printing technology, each super-hydrophilic functional sub-layer comprising a plurality of second elongated gel cylinders arranged at intervals.

[0015] The arrangement direction of the first gel cylinders and the second gel cylinders is an angle greater than 0 degrees and less than or equal to 90 degrees.

[0016] In some embodiments, the first gel cylinders, the second gel cylinders, and the junctions of the first gel cylinders and the second gel cylinders transport water due to capillary action.

[0017] In another aspect of the present application, a preparation method of the above-mentioned 3D-printed temperature-responsive water gel evaporator is provided, the preparation method comprising the following steps:

[0018] (1) 1g of sodium alginate is added to 5-10ml of water, and 50-100mg of pyrrole is stirred to obtain a first solution, 0.1-1g of polyvinyl alcohol and 0.1-0.5g of potassium persulfate are added to 3ml of deionized water and stirred to obtain a second solution, and the first solution and the second solution are mixed to obtain a first slurry;

[0019] (2) 1g of sodium alginate is added to 5-10ml of water, and 50-100mg of pyrrole is stirred to obtain a third solution, 0.1-1g of N-isopropyl acrylamide and 10-30mg of potassium persulfate are added to 3ml of deionized water, stirred, heated at 60-80℃, and then 0.1-0.5g of potassium persulfate is added and stirred to obtain a fourth solution, and the third solution and the fourth solution are mixed, reacted at room temperature, and then a second slurry is obtained;

[0020] (3) a three-dimensional model is designed in SolidWorks software, the three-dimensional model is a staggered line printing, the first slurry and the second slurry are loaded into the barrels of a 3D printer, the three-dimensional model is imported into the 3D printer, and printing is started;

[0021] (4) Print the first slurry and the second slurry into devices, and place them in a 0.5-2 mol / L CaCl2 solution to cure for 6-36 h to obtain the temperature-responsive 3D printed hydrogel evaporator.

[0022] In some embodiments, in step (2), the heating time is 30-50 minutes, and the resting is performed by placing the food in a refrigerator at a low temperature for 10-14 hours.

[0023] The reaction time at room temperature is 4-8 hours.

[0024] In some embodiments, in step (3), when printing interlaced lines, the spacing of the upper layer lines is set to 0.1 to 0.5 mm, and the spacing of the lower layer lines is set to 0.1 to 0.5 mm.

[0025] In some embodiments, in step (4), the first slurry and the second slurry are printed into a device with a height ratio of 1:0.2.

[0026] In some embodiments, sodium alginate, polyvinyl alcohol, and pyrrole in the first slurry are printed to form the lower layer of the evaporator with a hydrophilic layer.

[0027] The sodium alginate, N-isopropylacrylamide, and pyrrole in the second slurry were printed as the upper layer of the evaporator as a photothermal responsive layer.

[0028] The temperature-responsive 3D-printed gel evaporator and its preparation method according to embodiments of the present invention have at least one of the following advantages:

[0029] In this invention, a first slurry A is prepared by mixing sodium alginate, polyvinyl alcohol, and pyrrole, and a second slurry B is prepared by mixing sodium alginate, N-isopropylacrylamide, and pyrrole. The spatial structure is adjusted using 3D printing technology, and the mixture is integrally cured using a calcium chloride solution. The first slurry A possesses (super)hydrophilic properties and serves as the lower layer of the evaporator, providing timely moisture to the upper layer. The second slurry B serves as a photothermal responsive layer. The poly(N-isopropylacrylamide) is a thermosensitive polymer; above its low critical phase transition temperature (approximately 32°C), it undergoes a conformational change, transforming from hydrophilic to hydrophobic, and its molecular chains change from extended to coiled, squeezing out water, increasing the thickness of the evaporated water layer, reducing the interaction between water and the interface, and thus promoting evaporation.

[0030] In addition, under light irradiation, poly-N-isopropylacrylamide randomly divided the evaporation layer hydrogel into numerous small regions. These small regions consist of two parts with different temperatures. The hydrophobic structure has a higher temperature than the adjacent hydrophilic structure (evaporation endothermic). The temperature difference can effectively change the air convection above the interface, accelerate gas escape, and promote water evaporation.

[0031] Furthermore, the gel evaporator is 3D printed, and its internal space is adjustable, establishing multiple water transport channels (the hydrogel itself can transport water, and the water between the hydrogel lines also transports water due to capillary action). This breaks the limitation of water transport in traditional hydrogels, which is restricted by the internal pores of the hydrogel itself, and induces the Marangoni effect, giving the device excellent salt removal performance and avoiding pore blockage and reduced evaporation efficiency. Attached Figure Description

[0032] These and / or other aspects and advantages of the present invention will become apparent and readily understood from the following description of preferred embodiments taken in conjunction with the accompanying drawings, in which:

[0033] Figure 1 This is a structural model diagram of a temperature-responsive 3D-printed hydrogel evaporator according to an embodiment of the present invention;

[0034] Figure 2 yes Figure 1 The Marangoni effect diagram showing the temperature response of the 3D-printed hydrogel evaporator;

[0035] Figure 3 For the various embodiments of the present invention, the process was carried out using 100mw / cm 2 A photograph of the actual product after testing the salt removal capacity of the 3D-printed hydrogel evaporator under 8 hours of light exposure. Detailed Implementation

[0036] The technical solution of the present invention will be further described in detail below through embodiments and in conjunction with the accompanying drawings. In this specification, the same or similar reference numerals indicate the same or similar components. The following description of the embodiments of the present invention with reference to the accompanying drawings is intended to explain the overall inventive concept of the present invention and should not be construed as a limitation thereof.

[0037] See Figure 1 As addressed in the background section, embodiments of the present invention provide a temperature-responsive 3D-printed hydrogel evaporator, the 3D-printed hydrogel evaporator comprising:

[0038] The upper layer of the evaporator is a photothermal response layer, which includes N-isopropylacrylamide as a thermosensitive polymer.

[0039] The lower layer of the evaporator is a hydrophilic layer configured to supply moisture to the upper layer of the evaporator.

[0040] The upper and lower layers of the evaporator are integrated and solidified using 3D printing technology to adjust their spatial structure.

[0041] The integrated curing process is performed using a calcium chloride solution. The concentration of the calcium chloride solution is 0.5–2 mol / L. Of course, those skilled in the art can also use other suitable solutions for the curing process.

[0042] Specifically, the N-isopropylacrylamide undergoes a molecular conformational change above the low critical phase transition temperature, changing from hydrophilic to hydrophobic, and the molecular chain of the N-isopropylacrylamide changes from an extended type to a contracted type to squeeze out moisture.

[0043] In this invention, the upper and lower layers of the evaporator are configured with a porous, interlaced structure.

[0044] In addition, under light irradiation, poly-N-isopropylacrylamide randomly divided the evaporation layer hydrogel into numerous small regions. These small regions consist of two parts with different temperatures. The hydrophobic structure has a higher temperature than the adjacent hydrophilic structure (evaporation endothermic). The temperature difference can effectively change the air convection above the interface, accelerate gas escape, and promote water evaporation.

[0045] The multi-layered, interwoven structure can be formed as follows:

[0046] The upper layer of the evaporator includes multiple superhydrophilic functional sublayers prepared by 3D printing technology, and each superhydrophilic functional sublayer includes multiple slender first gel cylinders arranged at intervals between each other;

[0047] The lower layer of the evaporator includes multiple superhydrophilic functional sublayers prepared by 3D printing technology, and each superhydrophilic functional sublayer includes multiple slender second gel cylinders arranged at intervals between each other;

[0048] The first and second gel cylinders are arranged at an angle greater than 0 degrees and less than or equal to 90 degrees. Water is transported between the first and second gel cylinders, between the second and third gel cylinders, and at the junction of the first and second gel cylinders due to capillary action.

[0049] Furthermore, the gel evaporator is 3D printed, and its internal space is adjustable, establishing multiple water transport channels (the hydrogel itself can transport water, and the water between the hydrogel lines also transports water due to capillary action). This breaks the limitation of water transport in traditional hydrogels, which is restricted by the internal pores of the hydrogel itself, and induces the Marangoni effect, giving the device excellent salt removal performance and avoiding pore blockage and reduced evaporation efficiency.

[0050] See Figure 2 The image shows the Marangoni effect inside a temperature-responsive 3D-printed hydrogel evaporator.

[0051] The Marangoni effect describes the flow of fluid from a region of low surface tension to a region of high surface tension. The main causes of the Marangoni effect are concentration gradients or temperature gradients. Figure 2 From the center, the temperature rises from evaporator A to evaporator B, creating a temperature gradient, causing water vapor to rise. The salt concentration also increases from A to B, creating a concentration gradient, causing water vapor to flow back, thus forming an upward and downward water circulation. Laterally, a concentration gradient also exists in the water flowing up from the gel cylinder due to evaporation and capillary action, thus forming a horizontal water circulation.

[0052] Embodiments of the present invention also provide a method for preparing a temperature-responsive 3D-printed hydrogel evaporator, the method comprising the following steps:

[0053] (1) Add 1g of sodium alginate to 5-10ml of water and add 50-100mg of pyrrole and stir to obtain a first solution. Add 0.1-1g of polyvinyl alcohol and 0.1-0.5g of potassium persulfate to 3ml of deionized water and stir to obtain a second solution. Mix the first solution and the second solution to obtain a first slurry.

[0054] (2) Add 1g of sodium alginate to 5-10ml of water and add 50-100mg of pyrrole and stir to obtain a third solution. Add 0.1-1g of N-isopropylacrylamide and 10-30mg of potassium persulfate to 3ml of deionized water and stir. Heat at 60-80℃ and let stand. Then add 0.1-0.5g of potassium persulfate and stir to obtain a fourth solution. Mix the third solution and the fourth solution and react at room temperature to obtain a second slurry.

[0055] (3) Design a three-dimensional model in SolidWorks software. The three-dimensional model is printed with interlaced lines. Load the first slurry and the second slurry into the barrel of the 3D printer respectively. Import the three-dimensional model into the 3D printer and start printing.

[0056] (4) Print the first slurry and the second slurry into devices, and place them in a 0.5-2 mol / L CaCl2 solution to cure for 6-36 h to obtain the temperature-responsive 3D printed hydrogel evaporator.

[0057] In step (2), the heating time is 30-50 minutes, and the resting time is 10-14 hours in a refrigerator at a low temperature.

[0058] The reaction time at room temperature is 4-8 hours.

[0059] In step (3), when printing interlaced lines, the spacing of the upper layer lines is set to 0.1 to 0.5 mm, and the spacing of the lower layer lines is set to 0.1 to 0.5 mm.

[0060] In step (4), the first slurry and the second slurry are printed into a device with a height ratio of 1:0.2.

[0061] The sodium alginate, polyvinyl alcohol, and pyrrole in the first slurry are used to print the hydrophilic layer of the lower layer of the evaporator.

[0062] The sodium alginate, N-isopropylacrylamide, and pyrrole in the second slurry were printed as the upper layer of the evaporator as a photothermal responsive layer.

[0063] As described above, in the embodiments of the present invention, two different 3D printing slurries, a first slurry A and a second slurry B, are prepared, and the first slurry A and the second slurry B are 3D printed as an integral upper and lower layer solidified. To further understand the present invention, a volume of 1*1*1cm is used. 3 For example, the following description, in conjunction with preferred embodiments, uses a device printed with a single first slurry A and a second slurry B as an example for comparison. However, it should be understood that these descriptions are merely for further illustrating the features and advantages of the invention, and not for limiting the scope of the claims. The described embodiments are only some, not all, of the embodiments of the invention.

[0064] Example 1 (only first slurry A)

[0065] (1) Add 1g of sodium alginate to 10ml of water and add 100mg of pyrrole, stirring until homogeneous. Add 0.5g of polyvinyl alcohol and 0.1g of potassium persulfate to 3ml of deionized water and stir until homogeneous. Mix the two solutions thoroughly to form a slurry.

[0066] (2) Design a 3D model in SolidWorks software. Set the top layer line spacing to 0.3mm, the bottom layer line spacing to 0.1mm, and the top layer thickness to bottom layer thickness ratio to 1:0.2. Import the 3D model into the 3D printer and start printing. The printed size is 1*1*1cm. 3 The device was then placed in a 1 mol / L CaCl2 solution and cured for 24 hours. The curing was performed at 100 mW / cm². 2 The evaporation efficiency of the evaporator was tested under simulated sunlight, and the test results are shown in Table 1.

[0067] Example 2 (Second slurry B only)

[0068] (1) Add 1g of sodium alginate to 10ml of water and add 100mg of pyrrole, stirring until homogeneous. This is labeled as solution a. Add 0.3g of N-isopropylacrylamide and 20mg of potassium persulfate to 3ml of deionized water, stir until homogeneous, heat at 70℃ for 40mins, and then place in a refrigerator for 12 hours. After that, add 0.1g of potassium persulfate, labeled as solution b. Mix solutions a and b and react at room temperature for 6 hours to obtain the second slurry B.

[0069] (2) Design a 3D model in SolidWorks software. Set the line spacing of the upper layer of the slurry to 0.3mm and the line spacing of the lower layer to 0.1mm. The ratio of the upper layer to the lower layer is 1:0.2. Import the 3D model into the 3D printer and start printing.

[0070] (3) Print the paste into a 1*1*1cm size. 3 The device was then placed in a 1 mol / L CaCl2 solution and cured for 24 hours. The curing was performed at 100 mW / cm². 2 The evaporation efficiency of the evaporator was tested under simulated sunlight, and the test results are shown in Table 1.

[0071] Example 3

[0072] (1) Add 1g of sodium alginate to 10ml of water and add 100mg of pyrrole, stirring until homogeneous. Add 0.5g of polyvinyl alcohol and 0.1g of potassium persulfate to 3ml of deionized water and stir until homogeneous. Mix the two solutions thoroughly to obtain the first slurry A.

[0073] (2) Add 1g of sodium alginate to 10ml of water and 100mg of pyrrole, denoted as solution a. Add 0.3g of N-isopropylacrylamide and 20mg of potassium persulfate to 3ml of deionized water, stir well, heat in a water bath at 70℃ for 40mins, and then place in a refrigerator for 12 hours. Then add 0.1g of potassium persulfate, denoted as solution b. Mix solutions a and b and react at room temperature for 6 hours to obtain the second slurry B.

[0074] (3) Design the 3D model in SolidWorks software. Set the line spacing of A slurry printing to 0.1mm and the line spacing of B slurry printing to 0.2mm. Import the 3D model into the 3D printer and start printing.

[0075] (4) Print 1*1*1cm of A and B slurries at a height ratio of 1:0.2. 3 The device was then placed in a 1 mol / L CaCl2 solution and cured for 24 hours. The curing was achieved using a 1 mw / cm² solution. 2 The evaporation efficiency of the evaporator was tested under simulated sunlight, and the test results are shown in Table 1.

[0076] Example 4

[0077] (1) Add 1g of sodium alginate to 7ml of water and add 100mg of pyrrole, stirring until homogeneous. Add 0.5g of polyvinyl alcohol and 0.1g of potassium persulfate to 3ml of deionized water and stir until homogeneous. Mix the two solutions thoroughly to obtain the first slurry A.

[0078] (2) Add 1g of sodium alginate to 10ml of water and 100mg of pyrrole, denoted as solution a. Add 0.3g of N-isopropylacrylamide and 20mg of potassium persulfate to 3ml of deionized water, stir well, heat in a water bath at 70℃ for 40mins, and then place in a refrigerator for 12 hours. Then add 0.1g of potassium persulfate, denoted as solution b. Mix solutions a and b and react at room temperature for 6 hours to obtain the second slurry B.

[0079] (3) Design the 3D model in SolidWorks software. Set the line spacing of A slurry printing to 0.1mm and the line spacing of B slurry printing to 0.1mm. Import the 3D model into the 3D printer and start printing.

[0080] (4) Print the first slurry A and the second slurry B at a height ratio of 1:0.2 to a size of 1*1*1cm. 3 The device was then placed in a 1 mol / L CaCl2 solution and cured for 24 hours. The curing was achieved using a 1 mw / cm² solution. 2 The evaporation efficiency of the evaporator was tested under simulated sunlight, and the test results are shown in Table 1.

[0081] Example 5

[0082] (1) Add 1g of sodium alginate to 10ml of water and add 100mg of pyrrole, stirring until homogeneous. Add 0.5g of polyvinyl alcohol and 0.1g of potassium persulfate to 3ml of deionized water and stir until homogeneous. Mix the two solutions thoroughly to obtain the first slurry A.

[0083] (2) Add 1g of sodium alginate to 10ml of water and 100mg of pyrrole, denoted as solution a. Add 0.3g of N-isopropylacrylamide and 20mg of potassium persulfate to 3ml of deionized water, stir well, heat in a water bath at 70℃ for 40mins, and then place in a refrigerator for 12 hours. Then add 0.1g of potassium persulfate, denoted as solution b. Mix solutions a and b and react at room temperature for 6 hours to obtain the second slurry B.

[0084] (3) Design the 3D model in SolidWorks software. Set the line spacing of the first slurry A to 0.1mm and the line spacing of the second slurry B to 0.1mm. Import the 3D model into the 3D printer and start printing.

[0085] (4) Print the first slurry A and the second slurry B at a height ratio of 1:0.2 to a size of 1*1*1cm. 3 The device was then placed in a 1 mol / L CaCl2 solution and cured for 24 hours. The curing was achieved using a 1 mw / cm² solution. 2 The evaporation efficiency of the evaporator was tested under simulated sunlight, and the test results are shown in Table 1.

[0086] Example 6

[0087] (1) Add 1g of sodium alginate to 10ml of water and add 100mg of pyrrole, stirring until homogeneous. Add 0.5g of polyvinyl alcohol and 0.1g of potassium persulfate to 3ml of deionized water and stir until homogeneous. Mix the two solutions thoroughly to obtain the first slurry A.

[0088] (2) Add 1g of sodium alginate to 10ml of water and 100mg of pyrrole, denoted as solution a. Add 0.4g of N-isopropylacrylamide and 20mg of potassium persulfate to 3ml of deionized water, stir well, heat in a water bath at 70℃ for 40mins, and then place in a refrigerator for 12 hours. Then add 0.1g of potassium persulfate, denoted as solution b. Mix solutions a and b and react at room temperature for 6 hours to obtain the second slurry B.

[0089] (3) Design the 3D model in SolidWorks software. Set the line spacing of the first slurry A to 0.1mm and the line spacing of the second slurry B to 0.1mm. Import the 3D model into the 3D printer and start printing.

[0090] (4) Print the first slurry A and the second slurry B at a height ratio of 1:0.2 to a size of 1*1*1cm. 3 The device was then placed in a 1 mol / L CaCl2 solution and cured for 24 hours.

[0091] Through 1mw / cm 2 The evaporation efficiency of the evaporator was tested under simulated sunlight, and the test results are shown in Table 1.

[0092] Table 1. Evaporation efficiency of seawater (3.5% brine) in Examples 1-6

[0093]

[0094] Table 2 shows the evaporation efficiency of concentrated brine (20% brine) in Examples 1-6.

[0095]

[0096] The temperature-responsive 3D-printed gel evaporator and its preparation method according to embodiments of the present invention have at least one of the following advantages:

[0097] In this invention, a first slurry A is prepared by mixing sodium alginate, polyvinyl alcohol, and pyrrole, and a second slurry B is prepared by mixing sodium alginate, N-isopropylacrylamide, and pyrrole. The spatial structure is adjusted using 3D printing technology, and the mixture is integrally cured using a calcium chloride solution. The first slurry A possesses (super)hydrophilic properties and serves as the lower layer of the evaporator, providing timely moisture to the upper layer. The second slurry B serves as a photothermal responsive layer. The poly(N-isopropylacrylamide) is a thermosensitive polymer; above its low critical phase transition temperature (approximately 32°C), it undergoes a conformational change, transforming from hydrophilic to hydrophobic, and its molecular chains change from extended to coiled, squeezing out water, increasing the thickness of the evaporated water layer, reducing the interaction between water and the interface, and thus promoting evaporation.

[0098] In addition, under light irradiation, poly-N-isopropylacrylamide randomly divided the evaporation layer hydrogel into numerous small regions. These small regions consist of two parts with different temperatures. The hydrophobic structure has a higher temperature than the adjacent hydrophilic structure (evaporation endothermic). The temperature difference can effectively change the air convection above the interface, accelerate gas escape, and promote water evaporation.

[0099] Furthermore, the gel evaporator is 3D printed, and its internal space is adjustable, establishing multiple water transport channels (the hydrogel itself can transport water, and the water between the hydrogel lines also transports water due to capillary action). This breaks the limitation of water transport in traditional hydrogels, which is restricted by the internal pores of the hydrogel itself, and induces the Marangoni effect, giving the device excellent salt removal performance and avoiding pore blockage and reduced evaporation efficiency.

[0100] While some embodiments of the present general inventive concept have been shown and described, those skilled in the art will understand that changes may be made to these embodiments without departing from the principles and spirit of the present general inventive concept, the scope of which is defined by the claims and their equivalents.

Claims

1. A method for preparing a temperature-responsive 3D-printed hydrogel evaporator, characterized in that, The 3D-printed hydrogel evaporator includes: The upper layer of the evaporator is a photothermal response layer, which includes N-isopropylacrylamide as a thermosensitive polymer. The lower layer of the evaporator is a hydrophilic layer configured to supply moisture to the upper layer of the evaporator. The upper and lower layers of the evaporator are integrated and solidified using 3D printing technology to adjust their spatial structure. The preparation method includes the following steps: (1) Add 1g of sodium alginate to 5-10ml of water and add 50-100mg of pyrrole and stir to obtain a first solution. Add 0.1-1g of polyvinyl alcohol and 0.1-0.5g of potassium persulfate to 3ml of deionized water and stir to obtain a second solution. Mix the first solution and the second solution to obtain a first slurry. (2) Add 1g of sodium alginate to 5-10ml of water, and add 50-100mg of pyrrole and stir to obtain a third solution. Add 0.1-1g of N-isopropylacrylamide and 10-30mg of potassium persulfate to 3ml of deionized water, stir, and then heat at 60-80°C. o C. Heat and let stand, then add 0.1-0.5g of potassium persulfate and stir to obtain a fourth solution. Mix the third and fourth solutions and react at room temperature to obtain a second slurry. The heating time is 30-50 minutes, the standing time is 10-14 hours in a refrigerator, and the reaction time at room temperature is 4-8 hours. (3) Design a three-dimensional model in SolidWorks software. The three-dimensional model is printed with staggered lines. Load the first slurry and the second slurry into the barrel of the 3D printer respectively. Import the three-dimensional model into the 3D printer and start printing. When printing staggered lines, the spacing of the upper layer lines is set to 0.1-0.5mm and the spacing of the lower layer lines is set to 0.1-0.5mm. (4) Print the first slurry and the second slurry into a device with a height ratio of 1:0.

2. Print the first slurry as the lower layer of the evaporator with a hydrophilic layer and print the second slurry as the upper layer of the evaporator with a photothermal response layer. Place the device in a 0.5-2 mol / L CaCl2 solution to cure for 6-36 hours to obtain the temperature-responsive 3D printed hydrogel evaporator.

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