Self-repairing hydrophilic porous photo-thermal film and preparation method and application thereof
1. A preparation method of a self-repairing hydrophilic porous photo-thermal film is characterized by comprising the following steps:
mixing polyethylene glycol, polytetrahydrofuran and dicyclohexylmethane-4, 4' -diisocyanate for polymerization reaction to obtain a PU hydrophilic polymer;
mixing the PU hydrophilic polymer with an organic solvent to obtain a PU hydrophilic polymer solution;
mixing a carbon-based photo-thermal material and a salt template reagent to obtain a mixture;
and mixing the PU hydrophilic polymer solution and the mixture, and then sequentially carrying out curing, organic solvent removal, water washing and drying to obtain the self-repairing hydrophilic porous photo-thermal film.
2. The method according to claim 1, wherein the molar amount of the polyethylene glycol is 0 to 50% of the total molar amount of the polyethylene glycol and the polytetrahydrofuran, and the molar amount of the polyethylene glycol is not 0.
3. The method of claim 1, wherein the carbon-based photothermal material comprises one or more of carbon black, carbon nanotubes, graphene, and porous carbon.
4. The preparation method of claim 1 or 3, wherein the mass ratio of the carbon-based photothermal material to the PU hydrophilic polymer is 0.3-0.7: 1.
5. The method of claim 1, wherein the salt template reagent comprises NaCl, KCl, and MgCl2One or more of (a).
6. The preparation method of claim 1 or 5, wherein the mass ratio of the salt template agent to the PU hydrophilic polymer is 3-7: 1.
7. The method as claimed in claim 1, wherein the water washing is soaking in water bath, the water is replaced every 6h, and the time of the water washing is 48 h.
8. The method according to claim 1, wherein the polymerization reaction is carried out at a temperature of 60 to 80 ℃ for 48 to 72 hours.
9. The self-repairing hydrophilic porous photo-thermal film prepared by the preparation method of any one of claims 1 to 8.
10. The use of the self-healing hydrophilic porous photothermal film of claim 9 in the field of photothermal water evaporation.
Background
The fresh water occupies only 3 percent of the total water resource of the ball, and is vital to human survival and social development. However, with the growing population and environmental pollution, the shortage of fresh water has become a critical global problem. Therefore, the development of effective seawater or sewage desalination technology is imperative. Among all water treatment technologies, solar-driven water evaporation technology has attracted extensive research attention due to the green and renewable nature of solar energy. In recent years, in order to effectively improve the evaporation efficiency of water, researchers have devised a technique of solar-driven interfacial water evaporation by fixing the collected heat at the water-air interface, using most of the heat for liquid-gas phase transition, and reducing heat loss. In general, most of the reported solar driven interfacial evaporators consist of three parts: 1) a photothermal layer with broad band light absorption and high light-to-heat conversion capability, 2) a floating support layer with low thermal conductivity, 3) continuous hydrophilic channels outside or in the middle of the support layer for providing the water required for the evaporation process. In recent years, although many efficient solar-driven interfacial evaporators have been developed, in practical applications, the photothermal layer or the water channel may be scratched or corroded, thereby decreasing the water evaporation efficiency. Therefore, the development of a solar-driven interface evaporator having stable evaporation efficiency is a key to meet the demand of practical applications, and particularly, the development of a solar-driven interface evaporator capable of achieving the restoration of its photothermal water evaporation performance after damage.
With the development of supermolecule chemistry and synthetic chemistry, various self-repairing polymers have been successfully synthesized, which can repair damages by themselves and restore mechanical and chemical properties, but the current self-repairing photo-thermal film for solar-driven water evaporation can only repair chemical damages, and the water evaporation rate is not ideal (1)<1.31kg·m-2·h-1)。
Disclosure of Invention
In view of the above, the present invention aims to provide a self-repairing hydrophilic porous photo-thermal film, a preparation method thereof and applications thereof. The self-repairing hydrophilic porous photo-thermal film prepared by the invention has high water evaporation rate.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides a preparation method of a self-repairing hydrophilic porous photo-thermal film, which comprises the following steps:
mixing polyethylene glycol, polytetrahydrofuran and dicyclohexylmethane-4, 4' -diisocyanate for polymerization reaction to obtain a PU hydrophilic polymer;
mixing the PU hydrophilic polymer with an organic solvent to obtain a PU hydrophilic polymer solution;
mixing a carbon-based photo-thermal material and a salt template reagent to obtain a mixture;
and mixing the PU hydrophilic polymer solution and the mixture, and then sequentially carrying out curing, organic solvent removal, water washing and drying to obtain the self-repairing hydrophilic porous photo-thermal film.
Preferably, the molar weight of the polyethylene glycol accounts for 0-50% of the total molar weight of the polyethylene glycol and the polytetrahydrofuran, and the molar weight of the polyethylene glycol is not 0.
Preferably, the carbon-based photothermal material comprises one or more of carbon black, carbon nanotubes, graphene and porous carbon.
Preferably, the mass ratio of the carbon-based photo-thermal material to the PU hydrophilic polymer is 0.3-0.7: 1.
Preferably, the salt template reagent comprises NaCl, KCl and MgCl2One or more of (a).
Preferably, the mass ratio of the salt template agent to the PU hydrophilic polymer is 3-7: 1.
Preferably, the water washing is soaking in a water bath, the water is replaced every 6 hours, and the time of the water washing is 48 hours.
Preferably, the temperature of the polymerization reaction is 60-80 ℃, and the time is 48-72 hours.
The invention also provides the self-repairing hydrophilic porous photo-thermal film prepared by the preparation method of the technical scheme.
The invention also provides application of the self-repairing hydrophilic porous photo-thermal film in the field of photo-thermal water evaporation.
The invention provides a preparation method of a self-repairing hydrophilic porous photo-thermal film, which comprises the following steps: mixing polyethylene glycol, polytetrahydrofuran and dicyclohexylmethane-4, 4' -diisocyanate for polymerization reaction to obtain a PU hydrophilic polymer; mixing the PU hydrophilic polymer with an organic solvent to obtain a PU hydrophilic polymer solution; mixing a carbon-based photo-thermal material and a salt template reagent to obtain a mixture; and mixing the PU hydrophilic polymer solution and the mixture, and then sequentially carrying out curing, organic solvent removal, water washing and drying to obtain the self-repairing hydrophilic porous photo-thermal film.
The invention obtains the hydrophilic room temperature self-repairing PU Polymer (PU) through the gradual polymerization reaction of the polyurethanex) Mixing and curing the self-repairing hydrophilic polymer, the carbon-based photo-thermal material and a salt template reagent, and preparing the hydrophilic self-repairing porous photo-thermal film (SHPP film, PU film) by utilizing a template pore-forming methodxCarbon-based photothermal materialmSalt template reagentn) The water content and the water transmission capacity of the SHPP film can be controlled by adjusting the hydrophilicity of the self-repairing PU polymer and the mass ratio of the raw materials, so that the water evaporation performance is obviously influenced. And the self-healing PU polymer rejoins the fractured SHPP films together through recombination of hydrogen bonds between the fractured surfaces, resulting in restoration of structural integrity. The SHPP film can be used as a photothermal layer and a water transmission channel at the same time, and the SHPP film and Polyethylene (PE) foam are assembled together to easily manufacture a high-efficiency solar-driven interface evaporator, so that the evaporator is suspended on the water surface, and the evaporation rates of lake water and seawater respectively reach 1.67 kg.m-2·h-1And 1.61kg m-2·h-1. When the SHPP film is cut off, the photo-thermal water evaporation capacity of the evaporator is lost due to the fact that the evaporator loses water transmission capacity, and when the SHPP film can be repaired at room temperature, the water evaporation performance of the evaporator can be completely recovered. In addition, the SHPP film can repair the cut damage many times at the same position without losing its photothermal water evaporation performance. The SHPP film has the characteristics of low price, simple structure, excellent performance, long service life and the like, so that the distillation device formed by the SHPP film evaporator has wide application prospect in sewage purification and seawater desalination.
The preparation method provided by the invention is simple and reliable, the PU self-repairing hydrophilic polymer is obtained through polymerization step by step in one pot, post-treatment such as impurity removal is not needed, and finally the self-repairing porous photo-thermal film can be obtained through blending and salt template reagent removal.
The preparation method provided by the invention has low cost: polyethylene glycol (PEG) has very wide application in the industries of cosmetics, pharmacy, chemical fiber, rubber, plastics, paper making, paint, electroplating, pesticides, metal processing, food processing and the like; polytetrahydrofuran (PTMG) is useful as tires, power transmission belts, gaskets, and the like; it can also be used for paint, artificial leather, film, etc., and PEG and PTMG are common industrial raw materials. Secondly, the carbon-based photo-thermal material has wide raw material sources and simple preparation process. In addition, the preparation process and the characterization thereof do not need precise, complex and expensive instruments and equipment.
Further, the preparation method of the invention has high efficiency: firstly, PU with different hydrophilicities is prepared by adjusting the molar ratio of PEGxTo prepare PU with different water contents and different water transmission ratesxCarbon-based photothermal materialmSalt template reagentnSelf-repairing a porous photo-thermal film at room temperature; secondly, PU is realized by changing the content of the carbon-based photo-thermal materialxCarbon-based photothermal materialmSalt template reagentnThe porous photothermal membrane has stable pore structure, high light absorption capacity and high photothermal conversion capacity, and PU can be further regulated by changing the content of the salt template reagentxCarbon-based photothermal materialmSalt template reagentnThe water content and water transport speed of the porous photothermal film, as well as the reduction of light reflection by the porous structure further increases the light absorption capacity. By optimizing PUxCarbon-based photothermal materialmSalt template reagentnThe water content and the water transmission speed of the porous photothermal film and the heat-insulating polyethylene/polystyrene foam are used as a floating support layer, so that the photothermal utilization capacity can be maximized, and the heat loss can be effectively reduced, so that the water transmission rate and the evaporation rate are similar, the evaporation performance of solar-driven interface water can reach an optimal evaporation rate, and efficient photothermal interface water evaporation is realized.
Further, the method comprisesThe self-repairing hydrophilic porous photothermal film prepared by the invention has good stability: because of the PUxThe polymer contains hydrophobic PTMG, forms hydrophobic phase region in the polymer and a plurality of hydrogen bonds in the polymer, so that PU is obtainedxCarbon-based photothermal materialmSalt template reagentnThe room temperature self-repairing porous photo-thermal film still can keep stable structure underwater, and secondly, the application of the carbon-based photo-thermal material further improves the PUxCarbon-based photothermal materialmSalt template reagentnMechanical stability of room temperature self-repairing porous photothermal films, PUxCarbon-based photothermal materialmSalt template reagentnPorous photo-thermal film self-repairing at room temperature in acidity (1 wt% CH)3COOH), basic (1 wt% Na)2CO3) The structural integrity of the salt solution (3.5% NaCl) can be kept after the salt solution is continuously placed in the environment for 10 days, and the integrity of the porous structure can be still kept even after the salt solution is continuously placed in the working environment (hot water at 50 ℃) for 10 days.
Further, the self-repairing hydrophilic porous photothermal film prepared by the invention has a self-repairing function: since PEG and PTMG molecular chains have low glass transition temperatures, and synthesized PUxThe polymer has a large amount of hydrogen bond interaction force inside, so that the PU is preparedxThe polymer has excellent room temperature self-repairing performance; room temperature self-repairing PUxPolymer impartation to PU preparedxCarbon-based photothermal materialmSalt template reagentnThe porous photo-thermal film has excellent room temperature self-repairing capability, so when PU is usedxCarbon-based photothermal materialmSalt template reagentnWhen the porous photothermal film breaks in the actual use process, the damaged structure and the water channel of the porous photothermal film can be repaired spontaneously, so that the complete structure and the photothermal water evaporation performance of the porous photothermal film are recovered, the efficient photothermal water evaporation performance of the porous photothermal film can be recovered even after the physical damage is repaired for many times, the service life of the porous photothermal film is prolonged effectively, and the use stability of the porous photothermal film is improved.
Drawings
FIG. 1 shows PU in example 120/CB0.5/NaCl5A structural characterization spectrogram of the hole photothermal film and an application real object diagram,wherein (a) is PU20/CB0.5/NaCl5SEM section photograph of porous photothermal film, and (b) is PU20/CB0.5/NaCl5Optical photograph of porous photothermal film interface water evaporation device, and (c) is PU20/CB0.5/NaCl5An optical photo of the porous photothermal film interface water collecting device, wherein (d) is PU20/CB0.5/NaCl5A schematic cross-sectional view of the porous photothermal film interface water collection device;
FIG. 2 is a graph showing the change in water content and evaporation rate of the self-repairing hydrophilic porous photo-thermal film prepared in example 1, wherein (a) is PUx/CB0.5/NaCl5The water content and evaporation rate of the porous photothermal film vary with the mole percent of PEG, and (b) is PU20/CB0.5/NaClnThe water content and the evaporation rate of the porous photothermal film change with the NaCl mass ratio, and (c) is PU20/CBm/NaCl5The water content and the evaporation rate of the porous photothermal film are changed along with the mass ratio of the CB;
FIG. 3 shows PU20/CB0.7/NaCl5A cross-sectional SEM image of the porous photothermal film;
FIG. 4 shows PU20/CB0.5/NaCl7A cross-sectional SEM image of the porous photothermal film;
FIG. 5 shows PU20/CB0.5/NaCl5The photothermal water evaporation performance test curve of the porous photothermal film, wherein (a) is the presence or absence of PU20/CB0.5/NaCl5When the porous photo-thermal film is used, the water quality changes with the illumination time under the illumination of one sun, and (b) PU is utilized20/CB0.5/NaCl5When the porous photothermal film is used for simulating the evaporation of seawater and lake water, the water quality changes along with the illumination time, and (c) is PU20/CB0.5/NaCl5The original sample of the porous photothermal film, the sample after the cut mark damage and the sample after the repair are changed by the water quality along with the illumination time under the illumination of the sun, and (d) is PU20/CB0.5/NaCl5And the porous photo-thermal film is subjected to photo-thermal water evaporation rate and tensile stress restoration efficiency curve after multiple times of shear mark restoration at the same position.
Detailed Description
The invention provides a preparation method of a self-repairing hydrophilic porous photothermal film, which comprises the following steps;
mixing polyethylene glycol, polytetrahydrofuran and dicyclohexylmethane-4, 4' -diisocyanate for polymerization reaction to obtain a PU hydrophilic polymer;
mixing the PU hydrophilic polymer with an organic solvent to obtain a PU hydrophilic polymer solution;
mixing a carbon-based photo-thermal material and a salt template reagent to obtain a mixture;
and mixing the PU hydrophilic polymer solution and the mixture, and then sequentially carrying out curing, organic solvent removal, water washing and drying to obtain the self-repairing hydrophilic porous photo-thermal film.
In the present invention, unless otherwise specified, all the raw materials used are commercially available in the art.
The invention mixes polyethylene glycol, polytetrahydrofuran and dicyclohexylmethane-4, 4' -diisocyanate for polymerization reaction to obtain the PU hydrophilic polymer.
In the present invention, the molar amount of the polyethylene glycol is preferably 0 to 50%, more preferably 10%, 20%, 30%, 40% and 50% of the total molar amount of the polyethylene glycol and the polytetrahydrofuran.
In the invention, the molar ratio of the polyethylene glycol to dicyclohexylmethane-4, 4' -diisocyanate (DMDI) is preferably 0-5: 12, and more preferably 5/12, 4/12, 3/12, 2/12 or 1/12.
In the present invention, M of the polyethylene glycolwPreferably 500 to 2000, and more preferably 1000.
In the present invention, M of said polytetrahydrofuranwPreferably 500 to 2000, and more preferably 1000.
In the present invention, the polymerization reaction is preferably carried out under the condition of a catalyst, and the catalyst is preferably dibutyltin dilaurate (DBTDL). The amount of the catalyst used in the present invention is not particularly limited, and may be determined by a method known to those skilled in the art.
In the present invention, the polymerization reaction is preferably carried out in an organic solvent, preferably Tetrahydrofuran (THF), and the amount of the organic solvent used in the present invention is not particularly limited, and it is sufficient to ensure uniform mixing of the raw materials.
In the invention, the polymerization reaction temperature is preferably 60-80 ℃, and the time is preferably 48-72 h.
In a specific embodiment of the invention, the PEG and PTMG are preferably added separately to a three-neck round bottom flask with mechanical stirring, nitrogen inlet, condensed reflux. After stirring under vacuum at 100 ℃ for 2 hours, the system was cooled to 60 ℃ and filled with nitrogen, followed by addition of THF, DMDI, and DBTDL in a three-necked round-bottomed flask, with nitrogen blanket and stirring for the polymerization.
After the polymerization reaction is finished, the invention preferably uses an absolute ethyl alcohol dialysis membrane to dialyze and purify the obtained polymerization reaction product, and then dries the product to obtain the PU hydrophilic Polymer (PU)xX is the percentage of the molar ratio of PEG to the total molar amount of PEG and PTMG monomers, respectively calculated as PU0，PU10，PU20，PU30，PU40，PU50。
In the invention, the molecular weight cut-off of the absolute ethyl alcohol dialysis membrane is preferably 8000-14000 Da.
In the present invention, the drying is preferably natural evaporation.
After obtaining the PU hydrophilic polymer, the PU hydrophilic polymer is mixed with an organic solvent to obtain a PU hydrophilic polymer solution.
In the present invention, the organic solvent is preferably Tetrahydrofuran (THF), N-Dimethylformamide (DMF), or N, N-Dimethylacetamide (DMAC). The invention has no special limitation on the dosage of the organic solvent, and the PU hydrophilic polymer can be completely mixed.
According to the invention, a carbon-based photo-thermal material and a salt template reagent are mixed to obtain a mixture.
In the present invention, the carbon-based photothermal material preferably includes one or more of Carbon Black (CB), carbon nanotube, graphene, and porous carbon.
In the invention, the mass ratio of the carbon-based photothermal material to the PU hydrophilic polymer is preferably 0.3-0.7: 1, and more preferably 0.5-0.6: 1.
In the present invention, the salt template reagent preferably comprises NaCl, KCl and MgCl2One or more of (a).
In the present invention, the mixing is preferably ball milling, and the time of the ball milling is preferably 30 min.
After the PU hydrophilic polymer solution and the mixture are obtained, the PU hydrophilic polymer solution and the mixture are mixed and then are sequentially cured, the organic solvent is removed, washed and dried to obtain the self-repairing hydrophilic porous photo-thermal film.
The invention preferably adds the mixture to the PU hydrophilic polymer solution.
In the invention, the mass ratio of the salt template agent to the PU hydrophilic polymer is preferably 3-7: 1, and more preferably 5-6: 1.
In the present invention, the curing is preferably carried out in a tetrafluoro mold.
In the present invention, the water washing is preferably immersed in a water bath, preferably with water replaced every 6 hours, and the time of the water washing is preferably 48 hours. In the invention, the three-dimensional interconnected porous structure of the mixture of the carbon-based photothermal material and the salt template reagent is obtained after water washing, and the prepared porous film does not contain the salt template reagent.
In the present invention, the drying is preferably performed by removing water with filter paper in sequence and then naturally drying at room temperature.
The invention also provides the self-repairing hydrophilic porous photo-thermal film prepared by the preparation method of the technical scheme.
The invention also provides application of the self-repairing hydrophilic porous photo-thermal film in the field of photo-thermal water evaporation.
In the invention, the self-repairing hydrophilic porous photothermal membrane is preferably carried on a support layer to construct a high-efficiency photothermal water evaporation device.
In the present invention, the material of the support layer is preferably polyethylene or polystyrene foam.
In the invention, the application is preferably to prepare a photothermal water collecting device by using the self-repairing hydrophilic porous photothermal film.
In the invention, the photothermal water collection device preferably comprises a transparent pyramid-shaped polymethyl methacrylate (PMMA) box, a culture dish with the diameter of 140mm and filled with 200mL of water, and the self-repairing hydrophilic porous photothermal film, wherein under the irradiation of sunlight, water is evaporated and condensed on the PMMA protective layer, and under the action of gravity, condensed water reaches the bottom of the container and is collected.
To further illustrate the present invention, the self-healing hydrophilic porous photothermal films provided by the present invention, and the preparation method and application thereof, are described in detail below with reference to examples, which should not be construed as limiting the scope of the present invention.
Example 1
Types and sources of raw materials
Polyethylene glycol (PEG, M)w1000) was purchased from Sigma-Aldrich. Polytetrahydrofuran diol (PTMG, M)w1000) was purchased from alatin. Dicyclohexylmethane 4, 4-diisocyanate (DMDI, purity)>90%) was purchased from TCI. Catalyst dibutyltin dilaurate (DBTDL, purity)>97.5%) purchased from J&Company K. Ultra dry Tetrahydrofuran (THF) was purchased from Inokay. Carbon Black (CB) was purchased from alpha company.
PUxSynthesis of polymers
A series of PU with different PEG and PTMG molar ratios are prepared by a step-by-step polymerization method by using polyethylene glycol, polytetrahydrofuran diol and dicyclohexylmethane 4, 4-diisocyanate as raw materialsx. With PU50For example, PEG (5.00g,5mmol) and PTMG (5.00g,5mmol) were added to a 250mL three necked round bottom flask with mechanical stirring, nitrogen inlet, condensed reflux, respectively. After stirring under vacuum at 100 ℃ for 2 hours, the system was cooled to 60 ℃ and filled with nitrogen. THF (100mL), DMDI (3.15g,12mmol) and DBTDL (0.05g,0.08mmol) were then added to a three-necked round-bottomed flask. The reaction was stirred at 60 ℃ for 48h under nitrogen. Subsequently, the reaction solution was purified by dialysis using an absolute ethanol dialysis membrane (MWCO, 8000-. Finally, evaporating the ethanol to obtain PU50. According toThe above-mentioned method respectively synthesizes PU0、PU10、PU20、PU30、PU40。
PUx/CBm/NaClnPreparation of porous photothermal films
Mixing carbon black and sodium chloride with different mass ratios by adopting a ball mill. The CB and NaCl blend was added to 15mL PUxIn THF solution of the Polymer (PU)xIs dependent on PUx/CBm/NaClnM, n denote CB and NaCl relative to PU, respectivelyxMass ratio of polymer) and mechanically stirring them to mix them uniformly. The mixed solution was then poured into a tetrafluoroethylene mold and cured at room temperature. After THF is completely removed, the surface of the cured composite block is rubbed with abrasive paper, then soaked in a water bath, replaced once every 6h, and continuously washed with water for 2 days to completely remove NaCl, thus preparing PUx/CBm/NaClnPorous membrane, followed by sucking out PU with filter paperx/CBm/NaClnWater in the porous film and drying at room temperature to prepare PU0/CB0.5/NaCl5，PU10/CB0.5/NaCl5，PU20/CB0.5/NaCl5，PU30/CB0.5/NaCl5，PU40/CB0.5/NaCl5，PU50/CB0.5/NaCl5，PU20/CB0.3/NaCl5，PU20/CB0.5/NaCl3，PU20/CB0.5/NaCl7，PU20/CB0.7/NaCl5A porous photothermal film.
By PUxThe molar percentage of PEG in the polymer is used for preparing PU0/CB0.5/NaCl5，PU10/CB0.5/NaCl5，PU20/CB0.5/NaCl5，PU30/CB0.5/NaCl5，PU40/CB0.5/NaCl5，PU50/CB0.5/NaCl5The porous photothermal film researches the influence of the change of the mole percentage content of PEG on the evaporation rate of hydrothermal water; second, it is used forPreparing PU by adjusting the mass ratio of CB20/CB0.3/NaCl5，PU20/CB0.5/NaCl5，PU20/CB0.7/NaCl5A porous photothermal film is used for researching the change of photothermal water evaporation performance; finally, PU is prepared by adjusting the mass ratio of NaCl20/CB0.5/NaCl3，PU20/CB0.5/NaCl5，PU20/CB0.5/NaCl7The porous photothermal film is researched to change the photothermal water evaporation performance.
PUx/CBm/NaClnPreparation of porous photothermal film water evaporation device and water collection device
By using PUx/CBm/NaClnPorous light and heat membrane and polystyrene foam are as showy supporting layer, build high-efficient light and heat water evaporation plant and water collection device. The light hot water evaporator is composed of a PU20/CB0.5/NaCl5Porous photothermal film (11 cm × 11 cm) and a block of polystyrene foam (Φ 135 mm); the photo-thermal water collecting device comprises a transparent pyramid-shaped polymethyl methacrylate (PMMA) box, a culture dish with the diameter of 140mm and filled with 200mL of water, and PU20/CB0.5/NaCl5The porous photothermal film substrate water evaporation and evaporation device forms distillation equipment. Under the irradiation of sunlight, water is evaporated and condensed on the PMMA protective layer. The condensed water reaches the bottom of the container under the action of gravity and is then collected.
FIG. 1 shows PU20/CB0.5/NaCl5A structural characterization spectrogram of the pore photothermal film and an application object diagram, wherein (a) is PU20/CB0.5/NaCl5SEM section photograph of porous photothermal film, and (b) is PU20/CB0.5/NaCl5Optical photograph of porous photothermal film interface water evaporation device, and (c) is PU20/CB0.5/NaCl5An optical photo of the porous photothermal film interface water collecting device, wherein (d) is PU20/CB0.5/NaCl5The section of the porous photo-thermal film interface water collecting device is schematic.
FIG. 2 is a graph showing the change in water content and evaporation rate of the self-repairing hydrophilic porous photo-thermal film prepared in example 1, wherein (a) is PUx/CB0.5/NaCl5The water content and evaporation rate of the porous photothermal film vary with the mole percent of PEG, and (b) is PU20/CB0.5/NaClnThe water content and the evaporation rate of the porous photothermal film change with the NaCl mass ratio, and (c) is PU20/CBm/NaCl5The water content and evaporation rate of the porous photothermal film varied with the mass ratio of CB, and it was found that PU varied with the PEG contentx/CBm/NaClnThe porous photo-thermal film has a water content of 1.8-2.5 g/g-1PU according to NaCl contentx/CBm/NaClnThe porous photo-thermal film has a water content of 1.2-2.8 g-g-1Varying with the content of CB, PUx/CBm/NaClnThe porous photo-thermal film has a water content of 0.95-2.05 g-g-1Varying with the PEG content, PUx/CBm/NaClnThe water transmission rate of the porous photo-thermal film is in the range of 85.2-541 kg-m-2·h-1PU according to NaCl contentx/CBm/NaClnThe porous photothermal film has a water transfer rate in the range of 16.2 to 426kg · m-2·h-1Varying with the content of CB, PUx/CBm/NaClnThe water transmission rate of the porous photo-thermal film is 48-378 kg-m-2·h-1；PU20/CB0.5/NaCl5The self-repairing porous photothermal film has the highest water evaporation rate and efficiency.
The porosity and pore diameter of the self-repairing hydrophilic porous photo-thermal film prepared in example 1 were tested, and the results are as follows: depending on the PEG content, PUx/CBm/NaClnThe porosity of the porous photothermal film is substantially unchanged; PU according to NaCl contentx/CBm/NaClnThe porosity range of the porous photo-thermal film is 54-68 percent; PU as a function of the CB contentx/CBm/NaClnThe porosity range of the porous photothermal film is 38-59.8%; depending on the PEG content, PUx/CBm/NaClnPorous photothermal filmThe pore diameter of (A) is basically unchanged and is changed with the NaCl content, PUx/CBm/NaClnThe aperture of the porous photothermal film is increased from 7.2-59.9 μm to 4.8-270.7 μm, and PU is changed with the content of CBx/CBm/NaClnThe aperture of the porous photo-thermal film is increased from 6.5-32.4 μm to 9.7-109.8 μm.
Concrete PUx/CBm/NaClnThe porous photo-thermal film is synthesized by the following steps:
1)PU0synthesis of Polymer:
PEG (0.00g,0mmol) and PTMG (10.00g,10mmol) were added to a 250mL three necked round bottom flask with mechanical stirring, nitrogen inlet, condensed reflux, respectively. After stirring under vacuum at 100 ℃ for 2 hours, the system was cooled to 60 ℃ and filled with nitrogen. THF (100mL), DMDI (3.15g,12mmol) and DBTDL (0.05g,0.08mmol) were then added to a three-necked round-bottomed flask. The reaction was stirred at 60 ℃ for 48h under nitrogen. Subsequently, the reaction solution was purified by dialysis using an absolute ethanol dialysis membrane (MWCO,8000-14000 Da). Finally, evaporating the ethanol to obtain PU0。
PU0/CB0.5/NaCl5Preparing a porous photo-thermal film:
2.50g of CB and 25.00g of NaCl are mixed and ball-milled for 30min by a ball mill. Then, the above CB and NaCl blend was added to a solution of 5.00g of PU0The polymer was dissolved in 15mL of THF and mixed well by mechanical stirring. The mixed solution was then poured into a tetrafluoroethylene mold and cured at room temperature. After THF is completely removed, the surface of the cured composite block is rubbed with abrasive paper, then soaked in a water bath, replaced once every 6h, and continuously washed with water for 2 days to completely remove NaCl, thus preparing PU0/CB0.5/NaCl5Porous membrane, followed by sucking out PU with filter paper0/CB0.5/NaCl5Water in the porous membrane and dried at room temperature.
PU0/CB0.5/NaCl5Preparation of porous photothermal membrane water evaporation device
By using PU0/CB0.5/NaCl5Porous photothermal film and heat-insulating polyethylene as bleaching agentThe floating support layer builds a high-efficiency photo-thermal water evaporation device and a water collection device and floats in a square cup with 200mL of water. Under the irradiation of sunlight, the change of the quality of the cup system along with the illumination time is continuously measured.
PU0/CB0.5/NaCl5Photothermal water evaporation performance of porous photothermal film
PU0/CB0.5/NaCl5No PEG in the porous photothermal film, resulting in PU0/CB0.5/NaCl5The water content and water transport ability of the porous photothermal film become poor, and therefore, PU0/CB0.5/NaCl5The evaporation rate of the photo-thermal water is obviously limited, and the evaporation rate under the sun illumination is only 1.45 kg-m-2·h-1. In addition, as the content of PEG is reduced and the content of PTMG is increased, the Young modulus of the polymer is increased, the repairing performance is reduced, and the polymer PU0After being placed at room temperature for 48 hours, the repair efficiency is only 10.2 percent, and the PU is severely limited0/CB0.5/NaCl5The porous photo-thermal film repairs and reduces its service life.
2)PU50Synthesis of Polymer:
PEG (5.00g,5mmol) and PTMG (5.00g,5mmol) were added separately to a 250mL three necked round bottom flask equipped with mechanical stirring, nitrogen inlet, condensed reflux. After stirring under vacuum at 100 ℃ for 2 hours, the system was cooled to 60 ℃ and filled with nitrogen. THF (100mL), DMDI (3.15g,12mmol) and DBTDL (0.05g,0.08mmol) were then added to a three-necked round-bottomed flask. The reaction was stirred at 60 ℃ for 48h under nitrogen. Subsequently, the reaction solution was purified by dialysis using an absolute ethanol dialysis membrane (MWCO,8000-14000 Da). Finally, evaporating the ethanol to obtain PU50。
PU50/CB0.5/NaCl5Preparing a porous photo-thermal film:
2.50g of CB and 25.00g of NaCl are mixed and ball-milled for 30min by a ball mill. Then, the above CB and NaCl blend was added to a solution of 5.00g of PU50The polymer was dissolved in 15mL of THF and mixed well by mechanical stirring. Then pouring the mixed solution into the tetrafluoroIn an ethylene mold, curing was carried out at room temperature. After THF is completely removed, the surface of the cured composite block is rubbed with abrasive paper, then soaked in a water bath, replaced once every 6h, and continuously washed with water for 2 days to completely remove NaCl, thus preparing PU50/CB0.5/NaCl5Porous membrane, followed by sucking out PU with filter paper50/CB0.5/NaCl5Water in the porous membrane and dried at room temperature.
PU50/CB0.5/NaCl5Preparation of porous photothermal membrane water evaporation device
By using PU50/CB0.5/NaCl5The porous photothermal film and the heat-insulating polyethylene foam are used as floating support layers, and the efficient photothermal water evaporation device and the water collection device are built and float in a square cup with 200mL of water. Under the irradiation of sunlight, the change of the quality of the cup system along with the illumination time is continuously measured.
PU50/CB0.5/NaCl5Photothermal water evaporation performance of porous photothermal film
On the one hand, PU50/CB0.5/NaCl5The content of PEG in the porous photothermal film is high, so that PU is obtained50/CB0.5/NaCl5The porous photothermal film has an increased water content, resulting in an increased heat loss, while the porous photothermal film has a high PEG content, resulting in PU50/CB0.5/NaCl5The degree of swelling of the porous photothermal film is increased, so that the water transport ability of the pore structure is limited, and thus, PU50/CB0.5/NaCl5The evaporation rate of the photo-thermal water is obviously limited, and the evaporation rate under the sun illumination is only 1.58 kg-m-2·h-1。
3)PU20Synthesis of Polymer:
PEG (2.00g,2mmol) and PTMG (8.00g,8mmol) were added separately to a 250mL three necked round bottom flask equipped with mechanical stirring, nitrogen inlet, condensed reflux. After stirring under vacuum at 100 ℃ for 2 hours, the system was cooled to 60 ℃ and filled with nitrogen. THF (100mL), DMDI (3.15g,12mmol) and DBTDL (0.05g,0.08mmol) were then added to a three-necked round-bottomed flask. The reaction was stirred at 60 ℃ for 48h under nitrogen. Subsequently, the process of the present invention,and (3) dialyzing and purifying the reaction solution by using an absolute ethyl alcohol dialysis membrane (MWCO,8000-14000 Da). Finally, evaporating the ethanol to obtain PU20。
PU20/CB0.7/NaCl5Preparing a porous photo-thermal film:
3.50g of CB and 25.00g of NaCl are mixed and ball-milled for 30min by a ball mill. Then, the above CB and NaCl blend was added to a solution of 5.00g of PU20The polymer was dissolved in 15mL of THF and mixed well by mechanical stirring. The mixed solution was then poured into a tetrafluoroethylene mold and cured at room temperature. After THF is completely removed, the surface of the cured composite block is rubbed with abrasive paper, then soaked in a water bath, replaced once every 6h, and continuously washed with water for 2 days to completely remove NaCl, thus preparing PU20/CB0.7/NaCl5Porous membrane, followed by sucking out PU with filter paper20/CB0.7/NaCl5Water in the porous membrane and dried at room temperature.
PU20/CB0.7/NaCl5Preparation of porous photothermal membrane water evaporation device
By using PU20/CB0.7/NaCl5The porous photothermal film and the heat-insulating polyethylene foam are used as floating support layers, and the efficient photothermal water evaporation device and the water collection device are built and float in a square cup with 200mL of water. Under the irradiation of sunlight, the change of the quality of the cup system along with the illumination time is continuously measured.
PU20/CB0.7/NaCl5Photothermal water evaporation performance of porous photothermal film
PU20/CB0.7/NaCl5The content of CB in the porous photothermal film is high, so that PU is obtained20/CB0.7/NaCl5PU of porous photothermal film20The content is relatively reduced, resulting in a reduction in the water content in the porous film thereof, and therefore, PU20/CB0.7/NaCl5The evaporation rate of the photothermal water is influenced, and the evaporation rate under one sun illumination is reduced to 1.67 kg-m-2·h-1。
FIG. 3 shows PU20/CB0.7/NaCl5Cross-sectional SEM images of porous photothermal films.
4)PU20Synthesis of Polymer:
PEG (2.00g,2mmol) and PTMG (8.00g,8mmol) were added separately to a 250mL three necked round bottom flask equipped with mechanical stirring, nitrogen inlet, condensed reflux. After stirring under vacuum at 100 ℃ for 2 hours, the system was cooled to 60 ℃ and filled with nitrogen. THF (100mL), DMDI (3.15g,12mmol) and DBTDL (0.05g,0.08mmol) were then added to a three-necked round-bottomed flask. The reaction was stirred at 60 ℃ for 48h under nitrogen. Subsequently, the reaction solution was purified by dialysis using an absolute ethanol dialysis membrane (MWCO, 8000-. Finally, evaporating the ethanol to obtain PU20。
PU20/CB0.5/NaCl7Preparing a porous photo-thermal film:
2.50g of CB and 35.00g of NaCl are mixed and ball-milled for 30min by a ball mill. Then, the above CB and NaCl blend was added to a solution of 5.00g of PU20The polymer was dissolved in 15mL of THF and mixed well by mechanical stirring. The mixed solution was then poured into a tetrafluoroethylene mold and cured at room temperature. After THF is completely removed, the surface of the cured composite block is rubbed with abrasive paper, then soaked in a water bath, replaced once every 6h, and continuously washed with water for 2 days to completely remove NaCl, thus preparing PU20/CB0.5/NaCl7Porous membrane, followed by sucking out PU with filter paper20/CB0.5/NaCl7Water in the porous membrane and dried at room temperature.
PU20/CB0.5/NaCl7Preparation of porous photothermal membrane water evaporation device
By using PU20/CB0.5/NaCl7Porous photothermal films and heat-insulating polyethylene/polystyrene foam are used as floating support layers, a high-efficiency photothermal water evaporation device and a water collection device are built, and the device floats in a square cup with 200mL of water. Under the irradiation of sunlight, the change of the quality of the cup system along with the illumination time is continuously measured.
PU20/CB0.5/NaCl7Photothermal water evaporation performance of porous photothermal film
PU20/CB0.5/NaCl7In the preparation process of the porous photothermal film, a large amount of NaCl is added, so that the internal porous structure of the porous photothermal film is increased, the water content of the porous photothermal film is increased, the heat loss is increased, on the other hand, the water transmission capacity of the porous photothermal film is increased, the heat is transferred to bulk water, and therefore, PU (polyurethane)20/CB0.5/NaCl7The evaporation rate of the photo-thermal water is obviously limited, and the evaporation rate under the sun illumination is only 1.58 kg-m-2·h-1。
FIG. 4 shows PU20/CB0.5/NaCl7Cross-sectional SEM images of porous photothermal films.
5)PU20Synthesis of Polymer:
PEG (2.00g,2mmol) and PTMG (8.00g,8mmol) were added separately to a 250mL three necked round bottom flask equipped with mechanical stirring, nitrogen inlet, condensed reflux. After stirring under vacuum at 100 ℃ for 2 hours, the system was cooled to 60 ℃ and filled with nitrogen. THF (100mL), DMDI (3.15g,12mmol) and DBTDL (0.05g,0.08mmol) were then added to a three-necked round-bottomed flask. The reaction was stirred at 60 ℃ for 48h under nitrogen. Subsequently, the reaction solution was purified by dialysis using an absolute ethanol dialysis membrane (MWCO, 8000-. Finally, evaporating the ethanol to obtain PU20。
PU20/CB0.5/NaCl5Preparing a porous photo-thermal film:
2.50g of CB and 25.00g of NaCl are mixed and ball-milled for 30min by a ball mill. Then, the above CB and NaCl blend was added to a solution of 5.00g of PU20The polymer was dissolved in 15mL of THF and mixed well by mechanical stirring. The mixed solution was then poured into a tetrafluoroethylene mold and cured at room temperature. After THF is completely removed, the surface of the cured composite block is rubbed with abrasive paper, then soaked in a water bath, replaced once every 6h, and continuously washed with water for 2 days to completely remove NaCl, thus preparing PU20/CB0.5/NaCl5Porous membrane, followed by sucking out PU with filter paper20/CB0.5/NaCl5Water in the porous membrane and dried at room temperature.
PU20/CB0.5/NaCl5Preparation of porous photothermal membrane water evaporation device
By using PU20/CB0.5/NaCl5The porous photothermal film and the heat-insulating polyethylene foam are used as floating support layers, and the efficient photothermal water evaporation device and the water collection device are built and float in a square cup with 200mL of water. Under the irradiation of sunlight, the change of the quality of the cup system along with the illumination time is continuously measured.
PU20/CB0.5/NaCl5Photothermal water evaporation performance of porous photothermal film
FIG. 5 shows PU20/CB0.5/NaCl5The photothermal water evaporation performance test curve of the porous photothermal film, wherein (a) is the presence or absence of PU20/CB0.5/NaCl5When the porous photo-thermal film is used, the water quality changes with the illumination time under the illumination of one sun, and (b) PU is utilized20/CB0.5/NaCl5When the porous photothermal film is used for simulating the evaporation of seawater and lake water, the water quality changes along with the illumination time, and (c) is PU20/CB0.5/NaCl5The original sample of the porous photothermal film, the sample after the cut mark damage and the sample after the repair are changed by the water quality along with the illumination time under the illumination of the sun, and (d) is PU20/CB0.5/NaCl5And the porous photo-thermal film is subjected to photo-thermal water evaporation rate and tensile stress restoration efficiency curve after multiple times of shear mark restoration at the same position. As can be seen from FIG. 5, PU20/CB0.5/NaCl5The porous photothermal film has the best water evaporation performance, and the evaporation rate under the sun illumination is only 1.68 kg-m-2·h-1Furthermore, when PU20/CB0.5/NaCl5When the porous photothermal film is used for simulating the water evaporation of seawater and lake water, the porous photothermal film still has excellent water evaporation performance, and the evaporation rates of the porous photothermal film are respectively kept at 1.61 kg-m-2·h-1And 1.67kg m-2·h-1. Importantly, after the shear mark damage, the PU20/CB0.5/NaCl5The water evaporation performance of the porous photo-thermal film is obviously damaged, but after the repair, the porous photo-thermal film can be completely restored to the initial stateWater evaporation performance of (3); and after a plurality of times of kerf repair, although the repair efficiency corresponding to the tensile stress is reduced to 95%, the evaporation rate is still unchanged, which effectively prolongs the service life of the device.
The foregoing is merely a preferred embodiment of the invention and is not intended to limit the invention in any manner. It should be noted that, for those skilled in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be construed as the protection scope of the present invention.
