WO2022267258A1 - 一种具有Janus特性的复合气凝胶及其制备方法与应用 - Google Patents

一种具有Janus特性的复合气凝胶及其制备方法与应用 Download PDF

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WO2022267258A1
WO2022267258A1 PCT/CN2021/122036 CN2021122036W WO2022267258A1 WO 2022267258 A1 WO2022267258 A1 WO 2022267258A1 CN 2021122036 W CN2021122036 W CN 2021122036W WO 2022267258 A1 WO2022267258 A1 WO 2022267258A1
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janus
airgel
composite airgel
mxene
composite
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PCT/CN2021/122036
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English (en)
French (fr)
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王树荣
韩昕宏
丁少秋
邢博
周雍皓
朱玲君
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浙江大学
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
    • C08J9/28—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof by elimination of a liquid phase from a macromolecular composition or article, e.g. drying of coagulum
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/02—Treatment of water, waste water, or sewage by heating
    • C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
    • C02F1/14—Treatment of water, waste water, or sewage by heating by distillation or evaporation using solar energy
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
    • C08J9/0066—Use of inorganic compounding ingredients
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
    • C02F2103/08—Seawater, e.g. for desalination
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2201/00—Foams characterised by the foaming process
    • C08J2201/04—Foams characterised by the foaming process characterised by the elimination of a liquid or solid component, e.g. precipitation, leaching out, evaporation
    • C08J2201/048—Elimination of a frozen liquid phase
    • C08J2201/0484—Elimination of a frozen liquid phase the liquid phase being aqueous
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2301/00—Characterised by the use of cellulose, modified cellulose or cellulose derivatives
    • C08J2301/02—Cellulose; Modified cellulose
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/10—Metal compounds
    • C08K3/14—Carbides
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A20/00—Water conservation; Efficient water supply; Efficient water use
    • Y02A20/20—Controlling water pollution; Waste water treatment
    • Y02A20/208—Off-grid powered water treatment
    • Y02A20/212—Solar-powered wastewater sewage treatment, e.g. spray evaporation

Definitions

  • the invention relates to the technical field of airgel materials, in particular to the technical field of a composite airgel with Janus characteristics.
  • the photothermal material In the interface evaporation system, the photothermal material is located on the surface of the water body, and the heat generated by solar energy conversion can be confined to the air-water interface and directly used for the evaporation of surface water, thereby limiting the transfer of heat to the water body and significantly improving the evaporation efficiency.
  • photothermal materials only have a single wettability.
  • hydrophobic materials need to be supplemented with water transmission components, while hydrophilic materials will have their upper surface below the water surface over time, thus reducing the light absorption capacity. , water evaporation gradually becomes unstable.
  • the interface evaporation system is composed of several components, including photothermal conversion components, supporting heat insulation components and water transfer components, etc. .
  • Zhan et al. (ACS Appl. Nano Mater. 2020, 3, 5, 4690–4698) designed a double-layer interfacial photothermal evaporation system, in which carbon nanotube airgel is located in the lower layer as a thermal insulation layer, C/SiO 2 /Au airgel is located on the upper layer as a light-absorbing layer, and there is wool felt between the two layers for water transfer.
  • the water evaporation rate of the system under a standard solar light (1000W/m 2 ) is 1.32kg m -2 h - 1 , the evaporation efficiency is 79.6%.
  • Patent CN110183572A discloses an airgel, its preparation method and its application as a solar evaporator.
  • the airgel is composed of polyacrylamide airgel as the water supply layer and polyacrylamide-carbon nanotube airgel as the The light-absorbing layer, the double-layer structure of this airgel is composed of two independent airgels, and in the application as a solar evaporator, additional plastic foam is required to fix the support.
  • the purpose of the present invention is to solve the problems in the prior art, and propose a composite airgel with Janus characteristics and its preparation method and application, which can make the composite airgel independently and stably float on the water surface, and use it as an independent Solar interface evaporator.
  • the present invention proposes a composite airgel with Janus characteristics, including a composite airgel body, the composite airgel body includes a hydrophobic upper layer and a hydrophilic lower layer, and the upper layer is Hydrophobically modified cellulose nanofibrils/Ti 3 C 2 T x MXene airgel, the lower layer is cellulose nanofibril airgel, the junction of the upper layer and the lower layer is connected as a whole by chemical cross-linking, the composite A plurality of through holes are opened in the airgel body, and the through holes integrally penetrate the upper layer and the lower layer of the composite airgel body.
  • Janus means that the upper and lower parts of the composite airgel have opposite wettability.
  • Ti 3 C 2 T x MXene has a semi-metal-like energy band structure, which can induce the localized surface plasmon resonance effect, so it has outstanding photothermal conversion characteristics.
  • the internal photothermal conversion efficiency measured by the droplet photoheating system can be up to 100%.
  • the cellulose nanofibril in the present invention is a filamentous cellulose material that is separated from natural biomass, has a diameter of nanometers, a length of micrometers, and has both crystalline and non-crystalline regions.
  • the airgel obtained by winding and cross-linking cellulose nanofibrils not only has the unique hydrophilicity and biocompatibility of natural cellulose, but also has high mechanical stability.
  • the junction of the upper layer and the lower layer is cross-linked as a whole through hydrogen bonds and covalent bonds.
  • the diameter of the through hole is micron level.
  • the cross-section of the through hole is spindle-like.
  • the through holes are evenly distributed and vertically penetrate through the composite airgel body.
  • the cross-section of the through hole is similar to a spindle shape, the major axis of the cross-section has a dimension between tens and two hundred microns, and the minor axis has a dimension of about tens of microns.
  • the uniformly distributed and low tortuosity micron-scale through-holes inside the composite airgel are beneficial to the light trapping of the upper layer (multiple reflection, scattering, and absorption in the hole), the escape of water vapor, and the capillary action of the lower layer. Water absorption, and salt can diffuse back into the water body in the shortest path during seawater desalination applications, which makes the composite airgel have excellent salt tolerance.
  • the porosity of the composite airgel body is above 90%.
  • Porosity refers to the percentage of the volume of the pores in the airgel (including any form of pores existing inside the airgel) to the total volume of the airgel.
  • the composite airgel body is also provided with a pore structure with a pore size at the nanometer level.
  • Pores with a diameter of several hundred nanometers can also be observed at the crosslinks of the sheet-like network structure inside the composite airgel, which are formed by the interconnection between cellulose nanofibrils and Ti 3 C 2 T x MXene. form.
  • the cellulose nanofibrils/Ti 3 C 2 T x MXene airgel is an airgel structure with cellulose nanofibrils as the basic skeleton and Ti 3 C 2 T x MXene as the photothermal functional filler,
  • the cellulose nanofibril/Ti 3 C 2 T x MXene airgel is hydrophobically modified by a hydrophobic modifier.
  • cellulose nanofibrils as a matrix, cross-linked with Ti 3 C 2 T x MXene to form a double network, which effectively prevents the accumulation between Ti 3 C 2 T x MXene nanosheets, and then forms a rich pore structure, which is beneficial to improve the optical efficiency. Absorb and reduce thermal conductivity.
  • the mass ratio of cellulose nanofibrils to Ti 3 C 2 T x MXene is 1:1-4:1.
  • the mass ratio of the cellulose nanofibrils to Ti 3 C 2 T x MXene is 4:1 or 11: 4 or 2:1 or 3:2 or 1:1.
  • the present invention also protects a preparation method of a composite airgel with Janus characteristics, comprising the following steps:
  • Cross-linking and hydrophobic modification add a cross-linking agent to the mixed dispersion, after the first stirring, add a hydrophobic modifier to the mixed dispersion, and perform the second stirring to obtain hydrophobically modified cellulose Nanofibril/Ti 3 C 2 T x MXene dispersion;
  • c, double-layer combination first pour the cellulose nanofibril dispersion into the mold and freeze to obtain the lower layer of ice gel, then pour the cellulose nanofibril/ Ti 3 C 2 T x MXene dispersion, forming a gel overall;
  • step c has an auxiliary axial freezing function, and the whole gel obtained in step c is axially frozen, and freeze-dried after solidification;
  • the solvent in the gel grows directionally from bottom to top into ice crystals, which can be regarded as templates.
  • the ice crystals gradually sublimate, and finally leave through-holes inside the airgel. .
  • Heating heating the airgel obtained in step d to obtain a composite airgel with Janus characteristics.
  • the step c is: first pour the cellulose nanofibril/Ti 3 C 2 T x MXene dispersion prepared in the step b into a mold and freeze to obtain the ice gel of the lower layer, and then in the lower layer Pour the cellulose nanofibril dispersion on the ice gel to form the whole gel;
  • the same ice gel can be obtained by changing the pouring order of the upper dispersion liquid and the lower dispersion liquid;
  • the Ti 3 C 2 T x MXene dispersion is adjusted to be alkaline, the concentration of Ti 3 C 2 T x MXene in the mixed dispersion is 3-7.5g/L, and the cellulose nanofibril The concentration is 7.5-12g/L.
  • the stirring time for the first stirring is 3-5 hours, and the stirring time for the second stirring is 1-3 hours.
  • the crosslinking agent is selected from one of epichlorohydrin, ethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether and glutaraldehyde or Various.
  • the hydrophobic modifier is a silane coupling agent.
  • the silane coupling agent is selected from methyltrimethoxysilane, methyltriethoxysilane, perfluorooctyltriethoxysilane, 3-(methacryloyloxy)propane One or more of 3-(2,3-glycidoxy)propyltrimethoxysilane and 3-(2,3-glycidoxy)propyltrimethoxysilane.
  • the concentration of the crosslinking agent is 6-9 g/L
  • the concentration of the hydrophobic modifier is 6-9 g/L.
  • the freezing method is liquid nitrogen freezing, and the freezing time is 5-15 minutes.
  • the ultra-low temperature (-196°C) condition formed by liquid nitrogen can promote the nucleation of ice crystals and limit the growth of ice crystals (preventing the formation of large spherical ice crystals), thereby forming abundant pores in the gel network.
  • the entire gel formed is further subjected to solvent replacement treatment, tert-butanol aqueous solution is added to the mold, and the entire gel formed in step c is subjected to solvent replacement at room temperature, and the solvent replacement is completed Finally, the tert-butanol solution in the upper layer was sucked out to obtain a gel block.
  • the surface tension of tert-butanol is small, and replacing the filling solvent in the pores of the gel with it can avoid shrinkage and deformation of the gel structure during the drying process.
  • the solvent replacement treatment time is 10-18 hours, and the concentration of the tert-butanol aqueous solution is 20wt%-40wt%.
  • the bottom of the mold is made of a metal material with good thermal conductivity, and the surrounding area is made of a plastic material with poor thermal conductivity.
  • the freeze-drying temperature is -70° C. to -55° C.
  • the vacuum degree is 1-3 Pa
  • the time is 36-72 hours.
  • the heating temperature is 80-100° C.
  • the heating time is 0.5-3 hours.
  • Heat treatment can strengthen the covalent crosslinks within the composite airgel.
  • the present invention further protects an interface evaporator.
  • the interface evaporator adopts a composite airgel with Janus characteristics.
  • the composite airgel has a hydrophilic lower layer to absorb water and provides water for the hydrophobic upper layer.
  • the upper layer with light-to-heat conversion characteristics absorbs solar energy and converts it into heat energy for evaporating water.
  • the upper and lower parts of the composite airgel have opposite wettability. This structure allows the composite airgel to float independently and stably on the water surface. The upper part is exposed to the air and keeps dry; the lower part is immersed in water and fully absorbs water; the composite airgel The upper layer of the gel has light-to-heat conversion properties, which can absorb sunlight and convert it into heat, and the upper layer of the composite airgel also has thermal insulation, which can confine the heat inside the airgel.
  • the upper and lower layers of the composite airgel are combined into one structure without gaps, so when used as an interface evaporator, not only can other auxiliary parts be omitted, but also heat dissipation during the transfer and conversion process can be avoided to achieve efficient Heat utilization, the energy absorbed by the upper layer from the sun can be transferred to the maximum extent to the water in the lower gel network for rapid water evaporation.
  • the present invention also protects the use of the interface evaporator, which is used in seawater desalination, sewage treatment or water evaporation purification.
  • Composite airgel has excellent salt resistance, salt is not easy to precipitate on the surface, and its durability is good, it can be used for a long time, and it is suitable for seawater desalination and sewage treatment.
  • the evaporation of water at the interface of the composite airgel is more efficient than the direct evaporation of the water body, and its evaporation rate is at least 7.5 times faster than that of the water body alone under 1 sun light, which is suitable for the evaporation and purification of water.
  • the Janus characteristic of the upper part of the composite airgel is hydrophobic and the lower part is hydrophilic, so that it can independently and stably float at the air-water interface.
  • the lower part of the composite airgel is fully absorbed and immersed in water, and the upper part is kept dry and exposed to the air.
  • the upper and lower layers of the composite airgel are chemically linked together, there is no gap between them, which avoids heat dissipation to the outside through the gap, and the heat of the upper layer can be efficiently used for water evaporation.
  • the composite airgel has achieved excellent water evaporation performance. Under a standard sun irradiation, the water evaporation rate can reach 2.3kg m -2 h -1 , and the evaporation efficiency can reach more than 88%.
  • the upper part of the composite airgel has light-to-heat conversion characteristics, which can absorb sunlight and convert it into heat energy, and because of its low thermal conductivity (axial thermal conductivity 0.04-0.06W m -1 K -1 , diameter
  • the thermal conductivity coefficient is 0.02-0.04W m -1 K -1 ), which has excellent thermal insulation performance, which can reduce the dissipation of heat to the surrounding environment, so that the composite airgel does not need additional thermal insulation parts during the water evaporation process.
  • the lower part of the composite airgel has hydrophilic properties, and can continuously and stably transfer water upwards to the interface between the upper and lower layers through capillary action during the water evaporation process.
  • the rich pores of the composite airgel are beneficial to reduce the outward reflection of sunlight, and realize the efficient absorption of sunlight through multiple reflections and scattering in the pores (absorption rate can reach about 95.8%) .
  • the aligned through-hole structure with low tortuosity throughout the composite airgel is conducive to the escape of water vapor, and the water in the water body is transferred upward through the capillary action of the hydrophilic gel through-hole. Near the interface, the water in the through hole absorbs heat and escapes directly from the airgel along the through hole. And in the evaporation application process of seawater desalination, the salt deposited in the lower part can re-diffuse back to the seawater by the shortest path, avoiding the deposition of a large number of salt particles.
  • the Janus structure of the composite airgel is also beneficial to prevent the precipitation of salt particles. Due to the hydrophobicity of the upper layer, the seawater can only be confined to the lower layer, so the salt will not be transferred to the upper layer and will not cause With the blockage of the upper through-hole, water vapor can escape unhindered, while the excellent hydrophilicity of the lower layer can continuously absorb water upwards, and the salt can be dissolved in water, and the salt concentration gradient between the inside of the gel and the water body can promote the formation of salt. Re-diffusion back into the water body, so that a large number of salt particles do not form in the lower part of the gel to block the through-holes.
  • a mold with auxiliary axial freezing function is used.
  • the composite gel forms a temperature gradient in the axial direction, and the solvent inside the gel will grow into ice crystals from bottom to top and run through the gel. Overall, through-holes are formed inside the airgel after solvent sublimation.
  • the composite airgel is prepared by freezing the lower layer first, then pouring the upper layer of gel, and finally freeze-drying the whole.
  • the composite airgel is prepared by freezing the lower layer first, then pouring the upper layer of gel, and finally freeze-drying the whole.
  • Fig. 1 is the structural representation of a kind of composite airgel with Janus characteristic of the present invention
  • Fig. 2 is a schematic diagram of the chemical cross-linking mechanism of a composite airgel with Janus characteristics of the present invention
  • Fig. 3 is a schematic diagram of axial freezing in the preparation process of a composite airgel with Janus characteristics of the present invention
  • Fig. 4 is the scanning electron microscope image of embodiment 2 of the present invention.
  • Fig. 5 is the absorption spectrogram in the range of 200-2500nm wave band of embodiment 2 of the present invention.
  • Fig. 6 is the lower floor water contact angle test figure of embodiment 2 of the present invention.
  • Fig. 7 is the upper layer water contact angle test figure of embodiment 1-5 of the present invention.
  • Fig. 8 is the time-varying curve of water evaporation in Example 1-5 of the present invention.
  • Fig. 9 is the water evaporation rate versus time curve for different concentrations of brine in Example 2 of the present invention.
  • Fig. 10 is the water evaporation rate curve with time for evaporating 3.5wt% NaCl brine in continuous ten days in Example 2 of the present invention
  • Fig. 11 is three schematic cross-sectional views of spindle-like through-holes.
  • a kind of composite airgel with Janus characteristic comprises composite airgel body, is characterized in that: described composite airgel body comprises the upper layer 1 with hydrophobicity and the lower layer with hydrophilicity 2.
  • the upper layer 1 is hydrophobically modified cellulose nanofibrils/Ti 3 C 2 T x MXene airgel
  • the lower layer 2 is cellulose nanofibrils airgel
  • the junction of upper layer 1 and lower layer 2 is chemically cross-linked Functionally connected as a whole
  • there are several through holes 3 in the composite airgel body and the through holes 3 integrally run through the upper layer 1 and the lower layer 2 of the composite airgel body, and the junction of the upper layer 1 and the lower layer 2 cross-linked by hydrogen bonds and covalent bonds as a whole
  • the pore diameter of the through hole 3 is on the micron scale
  • the porosity of the composite airgel body is above 90%
  • the cross section of the through hole 3 is similar to Spindle-shaped
  • the through holes are formed by axial freezing.
  • the solvent in the gel grows into ice crystals from bottom to top.
  • the ice crystals can be regarded as templates.
  • the ice crystals sublimate gradually, and finally leave through-holes inside the airgel, and the cross-section of the obtained through-holes is spindle-like.
  • the preparation method of the composite airgel with Janus characteristics is as follows:
  • Step 1 Weigh 1.5 g of cellulose nanofibril powder, add it to 100 mL of NaOH aqueous solution with a pH of 10, stir magnetically for 30 minutes, add 0.75 g of epichlorohydrin, and continue stirring for 6 hours to obtain cellulose nanofibrils. Fibril dispersion;
  • Step 2 Add 2g Ti 3 AlC 2 to the mixed solution containing 2g LiF and 40mL 9M HCl, stir at 35°C for 24 hours, wash the product by centrifugation with deionized water until the pH of the supernatant is 6, and then use deionized Ionized water was used to redisperse the precipitate, and it was ultrasonically treated in an ice - water bath for 1 hour, and then centrifuged. Many Ti 3 C 2 T x MXene dispersions;
  • Step 3 Adjust the pH of the 4g/L Ti 3 C 2 T x MXene dispersion to 10 by adding dropwise 1M NaOH aqueous solution, and add 1.1 g of cellulose to 100 mL of the Ti 3 C 2 T x MXene dispersion at a pH of 10 Nanofibril powder, add 0.75g epichlorohydrin after magnetic stirring for 30 minutes, continue magnetic stirring for 4 hours, then add 0.75g methyltrimethoxysilane, continue magnetic stirring for 2 hours to obtain cellulose nanofibrils/Ti3 C 2 T x MXene dispersion;
  • Step 4 Take 20 mL of the dispersion obtained in Step 1 and pour it into a copper-based mold surrounded by polytetrafluoroethylene, and immerse the bottom of the mold in liquid nitrogen, freeze for 10 minutes and take it out;
  • Step 5 pour 20 mL of the dispersion obtained in Step 3 on the ice gel obtained in Step 4;
  • Step 6 At room temperature, add 40 mL of 30 wt % tert-butanol aqueous solution to the mold along the wall for 12 hours of solvent replacement, and suck out the upper layer of tert-butanol solution with a dropper after completion;
  • Step 7 Immerse the bottom of the mold in liquid nitrogen and freeze for 30 minutes, then freeze-dry for 48 hours at a temperature of -65°C and a vacuum of 1Pa;
  • Step 8 The obtained airgel was heated at 90° C. for 1 hour to obtain a finished product, labeled JC11M4.
  • Embodiment 2 is substantially the same as Embodiment 1, and the difference is that the preparation method of Embodiment 2 is as follows:
  • Step 1 same as step 1 of embodiment 1;
  • Step 2 same as step 1 of embodiment 1;
  • Step 3 Adjust the pH of the 5g/L Ti 3 C 2 T x MXene dispersion to 10 by adding 1M NaOH aqueous solution dropwise, and add 1g of cellulose nano Fibril powder, add 0.75g epichlorohydrin after magnetic stirring for 30 minutes, continue magnetic stirring for 4 hours, then add 0.75g methyltrimethoxysilane, continue magnetic stirring for 2 hours to obtain cellulose nanofibrils/Ti 3 C 2 T x MXene dispersion;
  • Step 4 Take 20 mL of the dispersion obtained in Step 1 and pour it into a copper-based mold surrounded by polytetrafluoroethylene, and immerse the bottom of the mold in liquid nitrogen, freeze for 10 minutes and take it out;
  • Step 5 pour 20 mL of the dispersion obtained in Step 3 on the ice gel obtained in Step 4;
  • Step 6 At room temperature, add 40 mL of 30 wt % tert-butanol aqueous solution to the mold along the wall for 12 hours of solvent replacement, and suck out the upper layer of tert-butanol solution with a dropper after completion;
  • Step 7 Immerse the bottom of the mold in liquid nitrogen and freeze for 30 minutes, then freeze-dry for 48 hours at a temperature of -65°C and a vacuum of 1Pa;
  • Step 8 The obtained airgel was heated at 90° C. for 1 hour to obtain a finished product, labeled JC10M5.
  • Embodiment 3 is substantially the same as Embodiment 1, and the difference is that the preparation method of Embodiment 3 is as follows:
  • Step 1 same as step 1 of embodiment 1;
  • Step 2 same as step 1 of embodiment 1;
  • Step 3 Adjust the pH of the 6 g/L Ti 3 C 2 T x MXene dispersion to 10 by adding dropwise 1M NaOH aqueous solution, and add 0.9 g of cellulose to 100 mL of the Ti 3 C 2 T x MXene dispersion at a pH of 10 Nanofibril powder, add 0.75g epichlorohydrin after magnetic stirring for 30 minutes, continue magnetic stirring for 4 hours, then add 0.75g methyltrimethoxysilane, continue magnetic stirring for 2 hours to obtain cellulose nanofibrils/Ti3 C 2 T x MXene dispersion;
  • Step 4 Take 20 mL of the dispersion obtained in Step 1 and pour it into a copper-based mold surrounded by polytetrafluoroethylene, and immerse the bottom of the mold in liquid nitrogen, freeze for 10 minutes and take it out;
  • Step 5 pour 20 mL of the dispersion obtained in Step 3 on the ice gel obtained in Step 4;
  • Step 6 At room temperature, add 40 mL of 30 wt % tert-butanol aqueous solution to the mold along the wall for 12 hours of solvent replacement, and suck out the upper layer of tert-butanol solution with a dropper after completion;
  • Step 7 Immerse the bottom of the mold in liquid nitrogen and freeze for 30 minutes, then freeze-dry for 48 hours at a temperature of -65°C and a vacuum of 1Pa;
  • Step 8 The obtained airgel was heated at 90° C. for 1 hour to obtain a finished product, labeled JC9M6.
  • Embodiment 4 is substantially the same as Embodiment 1, and the difference is that the preparation method of Embodiment 4 is as follows:
  • Step 1 same as step 1 of embodiment 1;
  • Step 2 same as step 1 of embodiment 1;
  • Step 3 Adjust the pH of the 4g/L Ti 3 C 2 T x MXene dispersion to 10 by adding 1M NaOH aqueous solution dropwise, and add 0.8 g of cellulose to 100 mL of the Ti 3 C 2 T x MXene dispersion with a pH of 10 Nanofibril powder, after magnetic stirring for 30 minutes, add 0.6g glutaraldehyde, continue magnetic stirring for 4 hours, then add 0.6g 3-(methacryloyloxy)propyltrimethoxysilane, continue magnetic stirring for 2 hours, get Cellulose nanofibrils/Ti 3 C 2 T x MXene dispersion;
  • Step 4 Take 20mL of the dispersion obtained in Step 1 and pour it into a copper-based mold surrounded by polytetrafluoroethylene, and immerse the bottom of the mold in liquid nitrogen, and take it out after freezing for 15 minutes;
  • Step 5 pour 20 mL of the dispersion obtained in Step 3 on the ice gel obtained in Step 4;
  • Step 6 At room temperature, add 40 mL of 30 wt % tert-butanol aqueous solution to the mold along the wall for 12 hours of solvent replacement, and suck out the upper layer of tert-butanol solution with a dropper after completion;
  • Step 7 Immerse the bottom of the mold in liquid nitrogen and freeze for 40 minutes, then freeze-dry for 72 hours at a temperature of -70°C and a vacuum of 2Pa;
  • Step 8 The obtained airgel was heated at 80° C. for 3 hours to obtain a finished product, labeled JC8M4.
  • Embodiment 5 is substantially the same as embodiment 1, and the difference is that the preparation method of embodiment 5 is as follows:
  • Step 1 same as step 1 of embodiment 1;
  • Step 2 same as step 1 of embodiment 1;
  • Step 3 Adjust the pH of the 6g/L Ti 3 C 2 T x MXene dispersion to 10 by adding 1M NaOH aqueous solution dropwise, and add 1.2 g of cellulose to 100 mL of the Ti 3 C 2 T x MXene dispersion at a pH of 10 Nanofibril powder, after magnetic stirring for 30 minutes, add 0.9g ethylene glycol diglycidyl ether, continue magnetic stirring for 3 hours, then add 0.9g perfluorooctyltriethoxysilane, continue magnetic stirring for 1 hour, to obtain cellulose Nanofibril/Ti 3 C 2 T x MXene dispersion;
  • Step 4 Take 20 mL of the dispersion obtained in Step 1 and pour it into a copper-based mold surrounded by polytetrafluoroethylene, and immerse the bottom of the mold in liquid nitrogen, freeze for 5 minutes and take it out;
  • Step 5 pour 20 mL of the dispersion obtained in Step 3 on the ice gel obtained in Step 4;
  • Step 6 At room temperature, add 40 mL of 30 wt % tert-butanol aqueous solution to the mold along the wall for 12 hours of solvent replacement, and suck out the upper layer of tert-butanol solution with a dropper after completion;
  • Step 7 Immerse the bottom of the mold in liquid nitrogen to freeze for 20 minutes, and then freeze-dry for 36 hours at a temperature of -55°C and a vacuum of 3Pa;
  • Step 8 The obtained airgel was heated at 100° C. for 0.5 hour to obtain a finished product, labeled JC12M6.
  • Embodiment 6 is a diagrammatic representation of Embodiment 6
  • Embodiment 6 is substantially the same as embodiment 1, and the difference is that the preparation method of embodiment 6 is as follows:
  • Step 1 same as step 1 of embodiment 1;
  • Step 2 same as step 1 of embodiment 1;
  • Step 3 Adjust the pH of the 3g/L Ti 3 C 2 T x MXene dispersion to 10.5 by adding 1M NaOH aqueous solution dropwise, and add 1.2 g of cellulose to 100 mL of the Ti 3 C 2 T x MXene dispersion with a pH of 10.5 Nanofibril powder, after magnetic stirring for 30 minutes, add 0.75g 1,4-butanediol diglycidyl ether, continue magnetic stirring for 5 hours, then add 0.75g methyltriethoxysilane, continue magnetic stirring for 1 hour, and get Cellulose nanofibrils/Ti 3 C 2 T x MXene dispersion;
  • Step 4 Take 15 mL of the dispersion obtained in Step 3 and pour it into a copper-based mold surrounded by polytetrafluoroethylene, and immerse the bottom of the mold in liquid nitrogen, freeze for 5 minutes and take it out;
  • Step 5 pour 15 mL of the dispersion obtained in Step 1 on the ice gel obtained in Step 4;
  • Step 6 At room temperature, add 30 mL of 20 wt % tert-butanol aqueous solution to the mold along the wall for 18 hours of solvent replacement, and suck out the upper layer of tert-butanol solution with a dropper after completion;
  • Step 7 Immerse the bottom of the mold in liquid nitrogen and freeze for 20 minutes, then freeze-dry for 36 hours at a temperature of -60°C and a vacuum of 2Pa;
  • Step 8 The obtained airgel is heated at 80° C. for 0.5 hour to obtain a finished product.
  • Embodiment 7 is a diagrammatic representation of Embodiment 7:
  • Embodiment 7 is substantially the same as Embodiment 1, and the difference is that the preparation method of Embodiment 7 is as follows:
  • Step 1 same as step 1 of embodiment 1;
  • Step 2 same as step 1 of embodiment 1;
  • Step 3 Adjust the pH of the 7.5g/L Ti 3 C 2 T x MXene dispersion to 9.5 by adding dropwise 1M NaOH aqueous solution, and add 0.75g of fiber to 100mL of the Ti 3 C 2 T x MXene dispersion with a pH of 9.5 Su nanofibril powder, add 0.75g glutaraldehyde after magnetic stirring for 30 minutes, continue magnetic stirring for 3 hours, then add 0.75g 3-(2,3-glycidyloxy)propyltrimethoxysilane, continue magnetic stirring After 3 hours, a cellulose nanofibril/Ti 3 C 2 T x MXene dispersion was obtained;
  • Step 4 Take 15 mL of the dispersion obtained in Step 3 and pour it into a copper-based mold surrounded by polytetrafluoroethylene, and immerse the bottom of the mold in liquid nitrogen, freeze for 15 minutes and take it out;
  • Step 5 pour 15 mL of the dispersion obtained in Step 1 on the ice gel obtained in Step 4;
  • Step 6 At room temperature, add 30mL of 40wt% tert-butanol aqueous solution to the mold along the wall for 10 hours of solvent replacement, and suck out the upper layer of tert-butanol solution with a dropper after completion;
  • Step 7 Immerse the bottom of the mold in liquid nitrogen to freeze for 30 minutes, and then freeze-dry for 48 hours at a temperature of -70°C and a vacuum of 2Pa;
  • Step 8 The obtained airgel is heated at 100° C. for 2 hours to obtain a finished product.
  • Example 2 is characterized by a scanning electron microscope, and the characterization results are shown in Figure 4.
  • a-c is the cross-section of the upper part of Example 2
  • c can observe a nanoscale pore structure
  • d is the implementation
  • e is the cross section of the lower part of Example 2.
  • the through hole in Example 2 has low tortuosity, and the cross section of the through hole is like a spindle.
  • This open through-hole structure is conducive to the escape of water vapor.
  • the water in the water body is transferred upward through the capillary action of the through-hole of the hydrophilic gel. When it is transferred to the vicinity of the interface between the upper and lower layers, the water in the through-hole absorbs heat and directly The airgel escapes along the through holes.
  • Example 2 The absorption spectrum of Example 2 was characterized by an ultraviolet-visible-near-infrared spectrophotometer, and the characterization results are shown in Figure 5.
  • the abscissa represents the test wavelength range, and the unit is nm.
  • the dotted line is the solar radiation spectrum, corresponding to the right ordinate, and the right ordinate is the irradiance of a specific wavelength, and the unit is W m -2 nm -1 .
  • the light absorptivity of Example 2 is shown by the solid line, which corresponds to the left ordinate, and the left ordinate is the light absorptivity in %.
  • the light absorption rate of Example 2 is about 95.8% within the test range.
  • the abscissa represents the time, the unit is s, and the ordinate represents the evaporation amount, the unit is kg m -2 .
  • Embodiment 2 is carried out the simulation test of interface evaporator application:
  • Example 2 was directly placed in a glass container filled with deionized water, and after the lower half of the container was fully absorbed, the glass container was placed under the irradiation of a solar simulator. Under the irradiation of two standard solar light intensities (2000W/m 2 ), when the steady water evaporation is achieved, the water evaporation rate is 3.199kg m -2 h -1 .
  • Example 2 was directly placed in a glass container filled with deionized water, and after the lower half of the container was fully absorbed, the glass container was placed under the irradiation of a solar simulator. Under the irradiation of three standard solar light intensities (3000W/m 2 ), when stable water evaporation is achieved, the water evaporation rate is 3.928kg m -2 h -1 .
  • Example 2 was directly placed in glass containers filled with 3.5wt%, 7wt% and 10.5wt% NaCl aqueous solutions. After the lower half of the glass container was fully absorbed, the glass container was placed under the irradiation of a solar simulator. After a standard sunlight for 6 hours, the water evaporation rate can reach 2.13, 2.03, 1.80kg m -2 h -1 respectively.
  • the experimental results are shown in Figure 9.
  • the abscissa is time and the unit is h
  • the ordinate is the evaporation rate
  • the unit is kg m -2 h -1
  • no salt particle deposition was observed on the upper surface of the composite airgel.
  • the aligned micron-sized through-holes with low tortuosity enable the salt to diffuse back into the water body in the shortest path, thus making Example 2 exhibit excellent salt tolerance.
  • Example 2 was directly placed in a glass container filled with 3.5wt% NaCl aqueous solution, and after the lower half of the container had fully absorbed water, the glass container was placed under the irradiation of a solar simulator. After a standard sunlight of 6 hours per day for 10 consecutive days, the water evaporation rate can still reach 1.95kg m -2 h -1 .
  • the experimental results are shown in Figure 10.
  • the X coordinate is time in h
  • the Y coordinate is time in day
  • the Z coordinate is evaporation rate in kg m -2 h -1 . Experiments prove that Example 2 has good durability.
  • Embodiment 2 is directly placed in a glass container filled with simulated seawater (Na + : 11505mg/L, Mg2+ : 1375mg/L, Ca2 + : 299mg/L), and placed under the irradiation of a solar simulator .
  • the concentration of Na + , Mg 2+ and Ca 2+ in the desalinated seawater recovered by condensation was significantly reduced to 1.486, 0.025, 0.584 mg/L.
  • Example 2 shows excellent desalination performance.

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Abstract

本发明公开了一种具有Janus特性的复合气凝胶，包括复合气凝胶本体，所述复合气凝胶本体包括具有疏水性的上层和具有亲水性的下层，上层为硅烷改性的纤维素纳米纤丝/Ti 3C 2T x MXene气凝胶，下层为纤维素纳米纤丝气凝胶，上层和下层的交界处通过化学交联作用联结为整体，所述复合气凝胶本体内开设有若干通孔，所述通孔一体贯穿所述复合气凝胶本体的上层和下层。复合气凝胶上部疏水下部亲水的Janus特性，使其可以独立地、稳定地漂浮于空气-水界面处，其下半部分充分吸水并浸于水中，上半部分保持干燥暴露于空气中，而且由于复合气凝胶的上下层通过化学作用联结在一起，其间没有缝隙，避免了热量通过缝隙向外界耗散，进而上层的热量可以高效地用于水蒸发。

Description

一种具有Janus特性的复合气凝胶及其制备方法与应用 【技术领域】
本发明涉及气凝胶材料的技术领域，特别是一种具有Janus特性的复合气凝胶的技术领域。
【背景技术】
从缓解能源危机和环境问题的角度来看，利用太阳能的光热转换驱动水快速蒸发是一种很有前景的淡水供应技术。而太阳能直接作用于水体的蒸发效率一般仅有30-45％。为实现更高的太阳能利用率，科研人员不断创新太阳能光热转换技术，目前新型的界面蒸发系统由于其较高的蒸发效率而备受关注。
界面蒸发系统中光热材料位于水体表面，太阳能转换生成的热量可以被局限于空气-水界面处直接用于表面水的蒸发，进而限制了热量向水体的传递，使蒸发效率显著提高。一般光热材料只具有单一润湿性，在界面蒸发应用中，疏水性的材料需辅以水传输部件，而亲水性的材料随使用时间推移其上表面会位于水面以下进而减弱光吸收能力，水蒸发逐渐不稳定。为了使光热材料稳定地处于空气-水界面处，并实现良好的热管理与水传递，界面蒸发系统多由几个部件共同构成，包括光热转换部件，支撑隔热部件和水传递部件等。
Zhan等(ACS Appl.Nano Mater.2020,3,5,4690–4698)设计了一种双层结构的界面光热蒸发系统，其中碳纳米管气凝胶位于下层作为隔热层，C/SiO 2/Au气凝胶位于上层作为光吸收层，两层间有羊毛毡用于水传递，该系统在一个标准太阳光照(1000W/m 2)下的水蒸发速率为1.32kg m -2h -1，蒸发效率为79.6％。专利CN110183572A公开了一种气凝胶、制备方法及其用作太阳能蒸发器的应用，所述气凝胶由聚丙烯酰胺气凝胶作为水供给层和聚丙烯酰胺-碳纳米管气凝胶作为光吸收层，该气凝胶的双层结构由两个独立的气凝胶组合而成，并且在用作太阳能蒸发器的应用中，需要额外的塑料泡沫来固定支撑。
为了实现光热材料的自漂浮，拥有Janus特性(即相反润湿性)的光热材料的研发逐渐 被关注。Yu等(Research 2020,2020,3241758)通过取向冷却结晶模板法、化学气相沉积以及单侧亲水化修饰方法获得了Janus聚偏氟乙烯薄膜，其在一个标准太阳照射下，水蒸发速率为1.08kg m -2h -1。该Janus薄膜并没有实现较高的水蒸发性能可归因于膜材料本身较差的热管理性能。该研究团队进一步将此薄膜与聚氨酯泡沫、吸水纸进行组装后，其水蒸发速率可提升至1.58kg m -2h -1。可见，开发集自漂浮、光吸收与转换、热管理以及水传输功能于一体的光热材料用于高效界面水蒸发具有重要意义。
【发明内容】
本发明的目的就是解决现有技术中的问题，提出具有Janus特性的复合气凝胶及其制备方法与应用，能够使复合气凝胶可以独立地稳定漂浮于水面，并将其用作独立的太阳能界面蒸发器。
为实现上述目的，本发明提出了一种具有Janus特性的复合气凝胶，包括复合气凝胶本体，所述复合气凝胶本体包括具有疏水性的上层和具有亲水性的下层，上层为疏水改性的纤维素纳米纤丝/Ti 3C 2T x MXene气凝胶，下层为纤维素纳米纤丝气凝胶，上层和下层的交界处通过化学交联作用联结为整体，所述复合气凝胶本体内开设有若干通孔，所述通孔一体贯穿所述复合气凝胶本体的上层和下层。
作为优选，所述Ti 3C 2T x MXene表面包含-OH、＝O、-F基团，所述纤维素纳米纤丝表面包含-OH基团。Janus是指所述复合气凝胶的上下两部分具有相反的润湿性。
本发明中的Ti 3C 2T x MXene是一种二维纳米材料，其中T x代表表面基团，包括-OH、＝O、-F等。Ti 3C 2T x MXene具有类半金属的能带结构，可以诱导局域表面等离子体共振效应，因而具有突出的光热转换特性，通过液滴光加热系统测得其内部光热转换效率可达100％。本发明中的Ti 3C 2T x MXene是利用LiF/HCl混合溶液选择性刻蚀Ti 3AlC 2的Al原子层得到，并结合超声处理获得纳米片结构。由于刻蚀体系为含氟水溶液体系，所以Ti 3C 2T x MXene表面含有-OH、＝O、-F等基团。
本发明中的纤维素纳米纤丝是一种从天然生物质分离得到的，直径在纳米级，长度在微 米级，并同时具有结晶和非结晶区的丝状纤维素材料。由纤维素纳米纤丝缠绕、交联得到的气凝胶不仅具有天然纤维素独特的亲水性和生物相容性，而且具有较高的机械稳定性。
作为优选，所述上层和下层的交界处通过氢键和共价键交联联结为整体。
纤维素纳米纤丝表面丰富的-OH基团以及Ti 3C 2T x MXene表面的-OH、＝O、-F基团之间形成氢键相互作用，并且交联剂的存在也使上下层的纤维素纳米纤丝和Ti 3C 2T x MXene通过形成共价键进行交联。由于复合气凝胶上下层为整体结构，没有缝隙，保温性能好，所以避免了热量传递过程中的耗散，实现高效的热量利用。
作为优选，所述通孔的孔径为微米级别。
作为优选，所述通孔的横截面为类纺锤形。
作为优选，所述通孔分布均匀，竖直贯穿于所述复合气凝胶本体。
通孔的横截面类似于纺锤形，横截面长轴的尺寸在几十到两百微米之间，短轴的尺寸约为几十微米。在界面蒸发应用中，所述复合气凝胶内部均匀分布的、低迂曲度的微米级通孔有利于上层的光捕获(孔内多重反射、散射和吸收)、水蒸气逃逸以及下层的毛细管作用水吸收，并且在海水淡化应用过程中盐能够以最短的路径扩散回到水体中，从而使得复合气凝胶具备出色的耐盐性。
作为优选，所述复合气凝胶本体的孔隙率在90％以上。
孔隙率是指气凝胶中的孔隙(包括气凝胶内部存在的任何形式的孔)体积与气凝胶总体积的百分比。
作为优选，所述复合气凝胶本体还开设有孔径在纳米级别的孔隙结构。
在复合气凝胶内部的片状网络结构的交联处也可观察到了直径为几百纳米级的孔隙，这些孔由纤维素纳米纤丝和Ti 3C 2T x MXene之间的相互联结而形成。
作为优选，所述纤维素纳米纤丝/Ti 3C 2T x MXene气凝胶是以纤维素纳米纤丝作为基本骨架，Ti 3C 2T x MXene作为光热功能填料的气凝胶结构，所述纤维素纳米纤丝/Ti 3C 2T x MXene气凝胶通过疏水改性剂进行疏水改性。
将纤维素纳米纤丝作为基体，与Ti 3C 2T x MXene交联形成双网络，有效防止了Ti 3C 2T x MXene纳米片之间的堆积，进而形成丰富的孔隙结构，利于提高光吸收与降低导热率。
作为优选，所述的纤维素纳米纤丝/Ti 3C 2T x MXene气凝胶中，纤维素纳米纤丝与Ti 3C 2T x MXene的质量比为1:1-4:1。
作为优选，所述的纤维素纳米纤丝/Ti 3C 2T x MXene气凝胶中,所述的纤维素纳米纤丝与Ti 3C 2T x MXene的质量比例为4:1或11:4或2:1或3:2或1:1。
本发明还保护一种具有Janus特性的复合气凝胶的制备方法，包括以下步骤：
a、纤维素纳米纤丝/Ti 3C 2T x MXene的混合分散液的制备：向Ti 3C 2T x MXene分散液中加入纤维素纳米纤丝粉末，搅拌均匀，得到纤维素纳米纤丝/Ti 3C 2T x MXene的混合分散液；
b、交联及疏水改性：向混合分散液中加入交联剂，进行第一次搅拌后，向混合分散液中加入疏水改性剂，进行第二次搅拌，得到疏水改性的纤维素纳米纤丝/Ti 3C 2T x MXene分散液；
c、双层结合:先将纤维素纳米纤丝分散液倒入模具中并进行冷冻，得到下层的冰凝胶，接着在下层的冰凝胶上倾倒步骤b制得的纤维素纳米纤丝/Ti 3C 2T x MXene分散液，形成凝胶整体；
因为下层为冰凝胶状态，所以两层之间会形成明显界面，不会发生混溶现象。由于纤维素纳米纤丝分散液和纤维素纳米纤丝/Ti 3C 2T x MXene的混合水分散液均具有较大粘度，所以恢复至室温两层之间也不会发生混溶。在上下层界面处的纤维素纳米纤丝和Ti 3C 2T x MXene之间存在氢键相互作用，并且界面处的交联剂会与纤维素纳米纤丝、Ti 3C 2T x MXene发生共价交联，所以上层和下层之间存在化学结合，可以无缝联结为整体；
d、成型：步骤c中的模具具有辅助轴向冷冻功能，对步骤c到的凝胶整体，进行轴向冷冻，凝固后进行冷冻干燥；
在轴向冷冻过程中，凝胶中的溶剂自下向上定向生长成冰晶，冰晶可以看作模板剂，在后续的冷冻干燥过程中冰晶逐渐升华，最终在气凝胶内部留下贯穿的通孔。
e、加热：将步骤d得到的气凝胶进行加热，得到具有Janus特性的复合气凝胶。
作为优选，所述步骤c为：先将步骤b制得的纤维素纳米纤丝/Ti 3C 2T x MXene分散液倒入模具中并进行冷冻，得到下层的冰凝胶，接着在下层的冰凝胶上倾倒纤维素纳米纤丝分散液，形成凝胶整体；
更换上层分散液和下层分散液倾倒的顺序，可以制得相同的冰凝胶；
作为优选，所述步骤a中，Ti 3C 2T x MXene分散液被调节至碱性，混合分散液中Ti 3C 2T x MXene浓度为3-7.5g/L，纤维素纳米纤丝的浓度为7.5-12g/L。
作为优选，所述步骤b中，所述的第一次搅拌，搅拌时间为3-5小时，所述的第二次搅拌，搅拌时间为1-3小时。
作为优选，所述步骤b中，所述的交联剂选自环氧氯丙烷、乙二醇二缩水甘油醚、1,4-丁二醇二缩水甘油醚和戊二醛的其中一种或多种。
作为优选，所述步骤b中，所述的疏水改性剂为硅烷偶联剂。
作为优选，所述步骤b中，硅烷偶联剂选自甲基三甲氧基硅烷、甲基三乙氧基硅烷，全氟辛基三乙氧基硅烷，3-(甲基丙烯酰氧)丙基三甲氧基硅烷，3-(2,3-环氧丙氧)丙基三甲氧基硅烷的其中一种或多种。
作为优选，所述步骤b中，交联剂的浓度为6-9g/L，疏水改性剂的浓度为6-9g/L。
作为优选，所述步骤c中，冷冻的方式为液氮冷冻，冷冻时间为5-15分钟。
由液氮形成的超低温(-196℃)条件可以促进冰晶成核并限制冰晶的生长(防止形成大球形冰晶)，进而在凝胶网络中形成丰富孔隙。
作为优选，在所述步骤c后，进一步地对形成的凝胶整体进行溶剂置换处理，将叔丁醇水溶液加入模具中，对步骤c形成的凝胶整体在室温下进行溶剂置换，溶剂置换结束后将上层的叔丁醇溶液吸出，得到凝胶块。
叔丁醇表面张力小，用其替换凝胶孔隙内的填充溶剂，可以避免干燥过程中凝胶结构发生收缩变形。
作为优选，所述的溶剂置换处理时间为10-18小时，所述叔丁醇水溶液的浓度为 20wt％-40wt％。
研究表明使用浓度在30wt％左右的叔丁醇溶液进行溶剂置换后得到的凝胶在冷冻时其内部可形成尺寸最小的叔丁醇-水共晶结构，有利于提高最终获得的气凝胶的孔隙率。
作为优选，所述d步骤中，所述模具底部为导热性好的金属材质，四周为导热性差的塑料材质，通过将模具的底部浸入液氮，使内部凝胶沿轴向进行定向冷冻，冷冻时间为20-40分钟。
由于只有导热性良好的模具底部浸入液氮，并且模具四周的导热性又较差，凝胶上下部分可形成温度梯度，进而促使了凝胶内部的溶剂冰晶沿轴向的单向生长，贯穿整体。
作为优选，所述步骤d中，冷冻干燥的温度为-70℃～-55℃，真空度为1-3Pa，时间为36-72小时。
作为优选，所述步骤e中，所述加热的温度为80-100℃，时间为0.5-3小时。
加热处理可以强化复合气凝胶内的共价交联。
本发明进一步保护一种界面蒸发器，所述的界面蒸发器采用具有Janus特性的复合气凝胶，所述复合气凝胶具有亲水性的下层吸收水分，为具有疏水性的上层提供水，具有光热转换特性的上层吸收太阳能转化为热能用于蒸发水分。
复合气凝胶的上下部分具有相反的润湿性，该结构使得复合气凝胶可以独立地稳定漂浮于水面，上半部分暴露于空气，保持干燥；下半部分浸入水中，充分吸水；复合气凝胶的上层具有光热转换特性，可吸收太阳光并转换生成热量，并且复合气凝胶的上层还具有保温性，可将热量局限在气凝胶内部。所述复合气凝胶上下层结合为一体结构，没有缝隙，因此在用作界面蒸发器时，不仅可省去其他辅助部件，还可避免热量在传递与转换过程中的耗散，实现高效的热量利用，上层从太阳吸收的能量可最大程度传递给下层凝胶网络中的水用于快速的水蒸发。
本发明还保护界面蒸发器的用途，所述的界面蒸发器应用于海水淡化、污水处理或水的蒸发提纯中。
复合气凝胶具有优秀的耐盐性，盐分不易在表面析出，而且其耐久性好，可以长时间使用，适用于海水淡化和污水处理。复合气凝胶界面水蒸发比水体直接蒸发更高效，在1个太阳光照下，其蒸发速率至少比单独水体快7.5倍，适用于水的蒸发提纯。
本发明的有益效果：
1、复合气凝胶上部疏水下部亲水的Janus特性，使其可以独立地、稳定地漂浮于空气-水界面处，其下半部分充分吸水并浸于水中，上半部分保持干燥暴露于空气中，而且由于复合气凝胶的上下层通过化学作用联结在一起，其间没有缝隙，避免了热量通过缝隙向外界耗散，进而上层的热量可以高效地用于水蒸发。复合气凝胶实现了卓越的水蒸发性能，其在一个标准太阳照射下，水蒸发速率可以达到2.3kg m -2h -1，蒸发效率可达88％以上。
2、复合气凝胶的上半部分具有光热转换特性，可以吸收太阳光并将其转换为热能，并且由于其导热系数低(轴向导热系数0.04-0.06W m -1K -1，径向导热系数0.02-0.04W m -1K -1)，其具有优异的保温性能，可以减小热量向周围环境的耗散，使得复合气凝胶在水蒸发过程无需额外的保温部件。
3、复合气凝胶的下半部分具有亲水特性，可以在水蒸发过程中持续稳定地通过毛细管作用向上传递水分至上下层界面处。
4、复合气凝胶丰富的孔隙(孔隙率＞90％)有利于减少太阳光向外的反射，并通过孔隙内的多重反射与散射实现太阳光的高效吸收(吸收率可达约95.8％)。而且贯穿于复合气凝胶整体的低迂曲度的对齐排列的通孔结构有利于水蒸气的逸出，水体的水通过亲水性凝胶通孔的毛细管作用被向上传递，当传递至上下层界面附近处时通孔内的水吸收热量后直接沿通孔逸出气凝胶。并且在海水淡化的蒸发应用过程中，下部分沉积的盐可以以最短路径重新扩散回海水，避免了大量盐颗粒的沉积。
5、在海水淡化应用中，复合气凝胶的Janus结构也有利于防止盐颗粒的析出，由于上层的疏水性，海水只能被局限在下层，因此盐分不会被传递至上层，不会导致上层通孔的堵塞，水蒸气可以无阻碍地逸出，而下层出色的亲水性，可以持续地向上吸水，盐分可以溶解 于水中，并且凝胶内部和水体之间的盐浓度梯度可促进盐分重新扩散回水体，因此凝胶下部不会形成大量的盐颗粒阻塞通孔。
6、制备过程中采用了具有辅助轴向冷冻功能的模具，冷冻时复合凝胶在轴向形成了温度梯度，凝胶内部的溶剂会自下而上地单向生长为冰晶，贯穿于凝胶整体，溶剂升华后气凝胶内部形成通孔。
7、采用先冷冻下层，再倾倒上层凝胶，最后冻干整体的方式制备复合气凝胶，倾倒上层凝胶时，因为下层为冰凝胶状态，所以两层之间会形成明显界面，不会发生混溶现象，恢复室温后，由于上下层粘度均较大，也不会发生混溶，使上下两层除了交界面以外都互相分离。
本发明的特征及优点将通过实施例结合附图进行详细说明。
【附图说明】
图1是本发明一种具有Janus特性的复合气凝胶的结构示意图；
图2是本发明一种具有Janus特性的复合气凝胶的化学交联机理示意图；
图3是本发明一种具有Janus特性的复合气凝胶的制备过程中轴向冷冻示意图；
图4是本发明实施例2的扫描电子显微镜图像；
图5是本发明实施例2在200-2500nm波段范围的吸收光谱图；
图6是本发明实施例2的下层水接触角测试图；
图7是本发明实施例1-5的上层水接触角测试图；
图8是本发明实施例1-5的水蒸发量随时间变化曲线；
图9是本发明实施例2对不同浓度盐水的水蒸发速率随时间变化曲线；
图10是本发明实施例2连续十天内蒸发3.5wt％NaCl盐水的水蒸发速率随时间变化曲线；
图11是类纺锤形通孔的三种横截面示意图。
图中：1-上层、2-下层、3-通孔。
【具体实施方式】
实施例1：
参阅图1和图2，一种具有Janus特性的复合气凝胶，包括复合气凝胶本体，其特征在于：所述复合气凝胶本体包括具有疏水性的上层1和具有亲水性的下层2，上层1为疏水改性的纤维素纳米纤丝/Ti 3C 2T x MXene气凝胶，下层2为纤维素纳米纤丝气凝胶，上层1和下层2的交界处通过化学交联作用联结为整体，所述复合气凝胶本体内开设有若干通孔3，所述通孔3一体贯穿所述复合气凝胶本体的上层1和下层2，所述上层1和下层2的交界处通过氢键和共价键交联联结为整体，所述通孔3的孔径为微米级别，所述复合气凝胶本体的孔隙率在90％以上，所述通孔3的横截面为类纺锤形，所述通孔3分布均匀，所述通孔3竖直贯穿于所述复合气凝胶本体，所述复合气凝胶本体还开设有孔径在纳米级别的孔隙结构，所述纤维素纳米纤丝/Ti 3C 2T x MXene气凝胶是以纤维素纳米纤丝作为基本骨架，Ti 3C 2T x MXene作为填料的气凝胶结构，所述纤维素纳米纤丝/Ti 3C 2T x MXene气凝胶通过硅烷偶联剂进行疏水改性。
参阅图3和图11，所述的通孔通过轴向冷冻形成，在轴向冷冻过程中，凝胶中的溶剂自下向上定向生长成冰晶，冰晶可以看作模板剂，在后续的冷冻干燥过程中冰晶逐渐升华，最终在气凝胶内部留下贯穿的通孔，得到的通孔的横截面为类纺锤形。所述具有Janus特性的复合气凝胶的制备方法如下：
步骤一：称取1.5g的纤维素纳米纤丝粉末，加入到100mL的PH为10的NaOH水溶液中，磁力搅拌30分钟后，加入0.75g环氧氯丙烷，继续搅拌6小时，得到纤维素纳米纤丝分散液；
步骤二：向含有2g LiF和40mL 9M HCl的混合溶液中添加2g Ti 3AlC 2,并在35℃搅拌24小时，使用去离子水离心洗涤产物，直到上清液的PH为6，然后使用去离子水对沉淀进行再分散，并于冰水浴中超声处理1h，再经过离心处理，上清液即Ti 3C 2T x MXene分散液；通过反复的再分散、超声和离心处理沉淀可以获得更多的Ti 3C 2T x MXene分散液；
步骤三：通过滴加1M NaOH水溶液调节4g/L的Ti 3C 2T x MXene分散液的PH为10，向100mL的PH为10的Ti 3C 2T x MXene分散液中加入1.1g纤维素纳米纤丝粉末，磁力搅拌30分钟后加入0.75g环氧氯丙烷，继续磁力搅拌4小时，再加入0.75g甲基三甲氧基硅烷，继续磁力搅拌2小时，得到纤维素纳米纤丝/Ti 3C 2T x MXene分散液；
步骤四：取20mL步骤一得到的分散液倒入以铜为基底、四周为聚四氟乙烯的模具中，并将模具底部浸入液氮中，冷冻10分钟后取出；
步骤五：在步骤四得到的冰凝胶上倾倒20mL步骤三得到的分散液；
步骤六：室温下，沿壁面向模具中加入40mL的30wt％叔丁醇水溶液，进行12小时的溶剂置换，结束后将上层叔丁醇溶液用滴管吸出；
步骤七：将模具底部浸入液氮中冷冻30分钟，然后进行48小时的冷冻干燥，温度为-65℃，真空度为1Pa；
步骤八：得到的气凝胶于90℃加热1小时，得到成品，标号JC11M4。
实施例2：
实施例2与实施例1基本相同，不同之处在于，实施例2的制备方法如下：
步骤一：与实施例1步骤一相同；
步骤二：与实施例1步骤一相同；
步骤三：通过滴加1M NaOH水溶液调节5g/L的Ti 3C 2T x MXene分散液的PH为10，向 100mL的PH为10的Ti 3C 2T x MXene分散液中加入1g纤维素纳米纤丝粉末，磁力搅拌30分钟后加入0.75g环氧氯丙烷，继续磁力搅拌4小时，再加入0.75g甲基三甲氧基硅烷，继续磁力搅拌2小时，得到纤维素纳米纤丝/Ti 3C 2T x MXene分散液；
步骤四：取20mL步骤一得到的分散液倒入以铜为基底、四周为聚四氟乙烯的模具中，并将模具底部浸入液氮中，冷冻10分钟后取出；
步骤五：在步骤四得到的冰凝胶上倾倒20mL步骤三得到的分散液；
步骤六：室温下，沿壁面向模具中加入40mL的30wt％叔丁醇水溶液，进行12小时的溶剂置换，结束后将上层叔丁醇溶液用滴管吸出；
步骤七：将模具底部浸入液氮中冷冻30分钟，然后进行48小时的冷冻干燥，温度为-65℃，真空度为1Pa；
步骤八：得到的气凝胶于90℃加热1小时，得到成品，标号JC10M5。
实施例3：
实施例3与实施例1基本相同，不同之处在于，实施例3的制备方法如下：
步骤一：与实施例1步骤一相同；
步骤二：与实施例1步骤一相同；
步骤三：通过滴加1M NaOH水溶液调节6g/L的Ti 3C 2T x MXene分散液的PH为10，向100mL的PH为10的Ti 3C 2T x MXene分散液中加入0.9g纤维素纳米纤丝粉末，磁力搅拌30分钟后加入0.75g环氧氯丙烷，继续磁力搅拌4小时，再加入0.75g甲基三甲氧基硅烷，继续磁力搅拌2小时，得到纤维素纳米纤丝/Ti 3C 2T x MXene分散液；
步骤四：取20mL步骤一得到的分散液倒入以铜为基底、四周为聚四氟乙烯的模具中，并将模具底部浸入液氮中，冷冻10分钟后取出；
步骤五：在步骤四得到的冰凝胶上倾倒20mL步骤三得到的分散液；
步骤六：室温下，沿壁面向模具中加入40mL的30wt％叔丁醇水溶液，进行12小时的溶剂置换，结束后将上层叔丁醇溶液用滴管吸出；
步骤七：将模具底部浸入液氮中冷冻30分钟，然后进行48小时的冷冻干燥，温度为-65℃，真空度为1Pa；
步骤八：得到的气凝胶于90℃加热1小时，得到成品，标号JC9M6。
实施例4：
实施例4与实施例1基本相同，不同之处在于，实施例4的制备方法如下：
步骤一：与实施例1步骤一相同；
步骤二：与实施例1步骤一相同；
步骤三：通过滴加1M NaOH水溶液调节4g/L的Ti 3C 2T x MXene分散液的PH为10，向100mL的PH为10的Ti 3C 2T x MXene分散液中加入0.8g纤维素纳米纤丝粉末，磁力搅拌30分钟后加入0.6g戊二醛，继续磁力搅拌4小时，再加入0.6g 3-(甲基丙烯酰氧)丙基三甲氧基硅烷，继续磁力搅拌2小时，得到纤维素纳米纤丝/Ti 3C 2T x MXene分散液；
步骤四：取20mL步骤一得到的分散液倒入以铜为基底、四周为聚四氟乙烯的模具中，并将模具底部浸入液氮中，冷冻15分钟后取出；
步骤五：在步骤四得到的冰凝胶上倾倒20mL步骤三得到的分散液；
步骤六：室温下，沿壁面向模具中加入40mL的30wt％叔丁醇水溶液，进行12小时的溶剂置换，结束后将上层叔丁醇溶液用滴管吸出；
步骤七：将模具底部浸入液氮中冷冻40分钟，然后进行72小时的冷冻干燥，温度为-70℃，真空度为2Pa；
步骤八：得到的气凝胶于80℃加热3小时，得到成品，标号JC8M4。
实施例5：
实施例5与实施例1基本相同，不同之处在于，实施例5的制备方法如下：
步骤一：与实施例1步骤一相同；
步骤二：与实施例1步骤一相同；
步骤三：通过滴加1M NaOH水溶液调节6g/L的Ti 3C 2T x MXene分散液的PH为10，向100mL的PH为10的Ti 3C 2T x MXene分散液中加入1.2g纤维素纳米纤丝粉末，磁力搅拌30分钟后加入0.9g乙二醇二缩水甘油醚，继续磁力搅拌3小时，再加入0.9g全氟辛基三乙氧基硅烷，继续磁力搅拌1小时，得到纤维素纳米纤丝/Ti 3C 2T x MXene分散液；
步骤四：取20mL步骤一得到的分散液倒入以铜为基底、四周为聚四氟乙烯的模具中，并将模具底部浸入液氮中，冷冻5分钟后取出；
步骤五：在步骤四得到的冰凝胶上倾倒20mL步骤三得到的分散液；
步骤六：室温下，沿壁面向模具中加入40mL的30wt％叔丁醇水溶液，进行12小时的溶剂置换，结束后将上层叔丁醇溶液用滴管吸出；
步骤七：将模具底部浸入液氮中冷冻20分钟，然后进行36小时的冷冻干燥，温度为-55℃，真空度为3Pa；
步骤八：得到的气凝胶于100℃加热0.5小时，得到成品，标号JC12M6。
实施例6：
实施例6与实施例1基本相同，不同之处在于，实施例6的制备方法如下：
步骤一：与实施例1步骤一相同；
步骤二：与实施例1步骤一相同；
步骤三：通过滴加1M NaOH水溶液调节3g/L的Ti 3C 2T x MXene分散液的PH为10.5，向100mL的PH为10.5的Ti 3C 2T x MXene分散液中加入1.2g纤维素纳米纤丝粉末，磁力搅拌30分钟后加入0.75g 1,4-丁二醇二缩水甘油醚，继续磁力搅拌5小时，再加入0.75g甲基三乙氧基硅烷，继续磁力搅拌1小时，得到纤维素纳米纤丝/Ti 3C 2T x MXene分散液；
步骤四：取15mL步骤三得到的分散液倒入以铜为基底、四周为聚四氟乙烯的模具中，并将模具底部浸入液氮中，冷冻5分钟后取出；
步骤五：在步骤四得到的冰凝胶上倾倒15mL步骤一得到的分散液；
步骤六：室温下，沿壁面向模具中加入30mL的20wt％叔丁醇水溶液，进行18小时的溶剂置换，结束后将上层叔丁醇溶液用滴管吸出；
步骤七：将模具底部浸入液氮中冷冻20分钟，然后进行36小时的冷冻干燥，温度为-60℃，真空度为2Pa；
步骤八：得到的气凝胶于80℃加热0.5小时，得到成品。
实施例7：
实施例7与实施例1基本相同，不同之处在于，实施例7的制备方法如下：
步骤一：与实施例1步骤一相同；
步骤二：与实施例1步骤一相同；
步骤三：通过滴加1M NaOH水溶液调节7.5g/L的Ti 3C 2T x MXene分散液的PH为9.5，向100mL的PH为9.5的Ti 3C 2T x MXene分散液中加入0.75g纤维素纳米纤丝粉末，磁力搅拌30分钟后加入0.75g戊二醛，继续磁力搅拌3小时，再加入0.75g 3-(2,3-环氧丙氧)丙基三甲氧基硅烷，继续磁力搅拌3小时，得到纤维素纳米纤丝/Ti 3C 2T x MXene分散液；
步骤四：取15mL步骤三得到的分散液倒入以铜为基底、四周为聚四氟乙烯的模具中，并将模具底部浸入液氮中，冷冻15分钟后取出；
步骤五：在步骤四得到的冰凝胶上倾倒15mL步骤一得到的分散液；
步骤六：室温下，沿壁面向模具中加入30mL的40wt％叔丁醇水溶液，进行10小时的溶剂置换，结束后将上层叔丁醇溶液用滴管吸出；
步骤七：将模具底部浸入液氮中冷冻30分钟，然后进行48小时的冷冻干燥，温度为-70℃，真空度为2Pa；
步骤八：得到的气凝胶于100℃加热2小时，得到成品。
通过扫描电子显微镜对实施例2进行表征，表征结果如图4所示，图中，a-c处为实施 例2的上层部分的横截面，c处可观察到纳米级的孔隙结构，d处为实施例2的上层部分纵截面,e处为实施例2的下层部分的横截面，图中可以观察到实施例2中的通孔具有低迂曲度，且通孔的横截面为类纺锤状。
这种开放通孔结构有利于水蒸气的逸出，水体的水通过亲水性凝胶通孔的毛细管作用被向上传递，当传递至上下层界面附近处时通孔内的水吸收热量后直接沿通孔逸出气凝胶。
通过紫外-可见-近红外分光光度计对实施例2的吸收光谱进行表征，表征结果如图5所示，图中，横坐标表示测试波长范围，单位为nm。虚线为太阳辐射光谱，对应于右侧纵坐标，右侧纵坐标为特定波长的辐照度，单位为W m -2nm -1。实施例2的光吸收率如实线所示，对应于左侧纵坐标，左侧纵坐标为光吸收率，单位为％。在测试范围内实施例2的光吸收率约为95.8％。
对实施例1-5的下层部分进行水接触角测试，其中实施例2测试结果如图6所示，结果表明，实施例1-5的下层部分具有很强的亲水性。
对实施例1-5的上层部分进行水接触角测试，测试结果如图7所示，图中，a表示实施例1，b表示实施例2，c表示实施例3，d表示实施例4，e表示实施例5。结果表明，实施例1-5的上层部分具有很强的疏水性。
将实施例1-5直接置于盛有去离子水的玻璃容器内，复合气凝胶可以独立漂浮，待其下半部分充分吸水后，将玻璃容器置于太阳光模拟器的照射下，在一个标准太阳光照下，达到稳定水蒸发时，水蒸发量随时间变化曲线速率如图8所示，水蒸发速率如表1所示：
表1
Figure PCTCN2021122036-appb-000001
图8中，横坐标表示时间，单位为s，纵坐标表示蒸发量，单位为kg m -2。
实验证明，本发明的复合气凝胶界面水蒸发明显比水体直接蒸发更高效，在1个太阳光照下，其蒸发速率至少比纯水快7.5倍。
对实施例2进行界面蒸发器应用的模拟试验：
将实施例2直接置于盛有去离子水的玻璃容器内，待其下半部分充分吸水后，将玻璃容器置于太阳光模拟器的照射下。在两个标准太阳光强(2000W/m 2)照射下，达到稳定水蒸发时，水蒸发速率为3.199kg m -2h -1。
将实施例2直接置于盛有去离子水的玻璃容器内，待其下半部分充分吸水后，将玻璃容器置于太阳光模拟器的照射下。在三个标准太阳光强(3000W/m 2)照射下，达到稳定水蒸发时，水蒸发速率为3.928kg m -2h -1。
将实施例2直接置于盛有3.5wt％，7wt％和10.5wt％NaCl水溶液的玻璃容器内，待其下半部分充分吸水后，将玻璃容器置于太阳光模拟器的照射下。在连续6小时的一个标准太阳光照后，水蒸发速率分别可达2.13，2.03，1.80kg m -2h -1，实验结果如图9所示，图中，横坐标为时间，单位为h，纵坐标为蒸发速率，单位为kg m -2h -1，并且复合气凝胶上表面未观察到有盐颗粒沉积。相较于错综复杂的网络结构，对齐排列的，低迂曲度的微米级通孔使得盐能够以最短的路径扩散回到水体中，从而使得实施例2体现出出色的耐盐性。
将实施例2直接置于盛有3.5wt％NaCl水溶液的玻璃容器内，待其下半部分充分吸水后，将玻璃容器置于太阳光模拟器的照射下。在连续10天每天6小时的一个标准太阳光照后，水蒸发速率仍可达1.95kg m -2h -1。实验结果如图10所示，图中，X坐标为时间，单位为h，Y坐标为时间，单位为天，Z坐标为蒸发速率，单位为kg m -2h -1。实验证明实施例2具有良好的耐久性。
将实施例2直接置于盛有模拟海水(Na +：11505mg/L，Mg 2+：1375mg/L，Ca 2+：299mg/L)的玻璃容器内，并置于太阳光模拟器的照射下。通过冷凝回收得到的淡化海水，其中Na +，Mg 2+和Ca 2+的浓度显著降低至1.486，0.025，0.584mg/L。实施例2体现出了优异的脱盐性能。
以上模拟应用实验证明，本发明的复合气凝胶可作为界面蒸发器应用于海水淡化、污水处理、水蒸发提纯中，具有很好的稳定性和高效性。
上述实施例是对本发明的说明，不是对本发明的限定，任何对本发明简单变换后的方案均属于本发明的保护范围。

Claims (27)

  1. 一种具有Janus特性的复合气凝胶，包括复合气凝胶本体，其特征在于：所述复合气凝胶本体包括具有疏水性的上层(1)和具有亲水性的下层(2)，上层(1)为疏水改性的纤维素纳米纤丝/Ti 3C 2T x MXene气凝胶，下层(2)为纤维素纳米纤丝气凝胶，上层(1)和下层(2)的交界处通过化学交联作用联结为整体，所述复合气凝胶本体内开设有若干通孔(3)，所述通孔(3)一体贯穿所述复合气凝胶本体的上层(1)和下层(2)。
  2. 如权利要求1所述的具有Janus特性的复合气凝胶，其特征在于：所述Ti 3C 2T x MXene表面包含-OH、＝O、-F基团，所述纤维素纳米纤丝表面包含-OH基团。
  3. 如权利要求1所述的具有Janus特性的复合气凝胶，其特征在于：所述上层(1)和下层(2)的交界处通过氢键和共价键交联联结为整体。
  4. 如权利要求1所述的具有Janus特性的复合气凝胶，其特征在于：所述通孔(3)的孔径为微米级别。
  5. 如权利要求1所述的具有Janus特性的复合气凝胶，其特征在于：所述通孔(3)的横截面为类纺锤形。
  6. 如权利要求1所述的具有Janus特性的复合气凝胶，其特征在于：所述通孔(3)分布均匀，竖直贯穿于所述复合气凝胶本体。
  7. 如权利要求1所述的具有Janus特性的复合气凝胶，其特征在于：所述复合气凝胶本体中的孔隙率在90％以上。
  8. 如权利要求1所述的具有Janus特性的复合气凝胶，其特征在于：所述复合气凝胶本体还开设有孔径在纳米级别的孔隙结构。
  9. 如权利要求1所述的具有Janus特性的复合气凝胶，其特征在于：所述纤维素纳米纤丝/Ti 3C 2T x MXene气凝胶是以纤维素纳米纤丝作为基本骨架，Ti 3C 2T x MXene作为光热功能填料的气凝胶结构，所述纤维素纳米纤丝/Ti 3C 2T x MXene气凝胶通过疏水改性剂进行疏水改性。
  10. 如权利要求9所述的具有Janus特性的复合气凝胶，其特征在于：所述的纤维素纳米纤丝/Ti 3C 2T x MXene气凝胶中，纤维素纳米纤丝与Ti 3C 2T x MXene的质量比为1:1-4:1。
  11. 如权利要求10所述的具有Janus特性的复合气凝胶，其特征在于：所述的纤维素纳米纤丝/Ti 3C 2T x MXene气凝胶中,纤维素纳米纤丝与Ti 3C 2T x MXene的质量比为4:1或11:4或2:1或3:2或1:1。
  12. 如权利要求1至11中任一项所述的具有Janus特性的复合气凝胶的制备方法，包括以下步骤：
    a、纤维素纳米纤丝/Ti 3C 2T x MXene的混合分散液的制备：向Ti 3C 2T x MXene分散液中加入纤维素纳米纤丝粉末，搅拌均匀，得到纤维素纳米纤丝/Ti 3C 2T x MXene的混合分散液；
    b、交联及疏水改性：向混合分散液中加入交联剂，进行第一次搅拌后，向混合分散液中加入疏水改性剂，进行第二次搅拌，得到疏水改性的纤维素纳米纤丝/Ti 3C 2T x MXene分散液；
    c、双层结合：先将纤维素纳米纤丝分散液倒入模具中并进行冷冻，得到下层的冰凝胶，接着在下层的冰凝胶上倾倒步骤b制得的纤维素纳米纤丝/Ti 3C 2T x MXene分散液，形成凝胶整体；
    d、成型：步骤c中的模具具有辅助轴向冷冻功能，对步骤c到的凝胶整体进行轴向冷冻，凝固后进行冷冻干燥；
    e、加热：将步骤d得到的气凝胶进行加热，得到具有Janus特性的复合气凝胶。
  13. 如权利要求12所述的具有Janus特性的复合气凝胶的制备方法，其特征在于：所述步骤a中，Ti 3C 2T x MXene分散液被调节至碱性，混合分散液中Ti 3C 2T x MXene浓度为3-7.5g/L，纤维素纳米纤丝的浓度为7.5-12g/L。
  14. 如权利要求12所述的具有Janus特性的复合气凝胶的制备方法，其特征在于：所述步骤b中，所述的第一次搅拌，搅拌时间为3-5小时，所述的第二次搅拌，搅拌时间为1-3小时。
  15. 如权利要求12所述的具有Janus特性的复合气凝胶的制备方法，其特征在于：所述步骤b中，所述的交联剂选自环氧氯丙烷、乙二醇二缩水甘油醚、1,4-丁二醇二缩水甘油醚和戊二醛的其中一种或多种。
  16. 如权利要求12所述的具有Janus特性的复合气凝胶的制备方法，其特征在于：所述步骤b中，所述的疏水改性剂为硅烷偶联剂。
  17. 如权利要求16所述的具有Janus特性的复合气凝胶的制备方法，其特征在于：所述步骤b中，硅烷偶联剂选自甲基三甲氧基硅烷、甲基三乙氧基硅烷，全氟辛基三乙氧基硅烷，3-(甲基丙烯酰氧)丙基三甲氧基硅烷，3-(2,3-环氧丙氧)丙基三甲氧基硅烷的其中一种或多种。
  18. 如权利要求12所述的具有Janus特性的复合气凝胶的制备方法，其特征在于：所述步骤b中，交联剂的浓度为6-9g/L，疏水改性剂的浓度为6-9g/L。
  19. 如权利要求12所述的具有Janus特性的复合气凝胶的制备方法，其特征在于：所述步骤c中，冷冻的方式为液氮冷冻，冷冻时间为5-15分钟。
  20. 如权利要求12所述的具有Janus特性的复合气凝胶的制备方法，其特征在于，所述步骤c为：先将步骤b制得的纤维素纳米纤丝/Ti 3C 2T x MXene分散液倒入模具中并进行冷冻，得到下层的冰凝胶，接着在下层的冰凝胶上倾倒纤维素纳米纤丝分散液，形成凝胶整体。
  21. 如权利要求12所述的具有Janus特性的复合气凝胶的制备方法，其特征在于：在所述步骤c后，进一步地对形成的凝胶整体进行溶剂置换处理，将叔丁醇水溶液加入模具中，对步骤c形成的凝胶整体在室温下进行溶剂置换，溶剂置换结束后将上层的叔丁醇溶液吸出，得到凝胶块。
  22. 如权利要求21所述的具有Janus特性的复合气凝胶的制备方法，其特征在于：所述的溶剂置换处理时间为10-18小时，所述叔丁醇水溶液的浓度为20wt％-40wt％。
  23. 如权利要求12所述的具有Janus特性的复合气凝胶的制备方法，其特征在于：所述步骤d中，所述模具的底部为导热性好的金属材质，四周为导热性差的塑料材质，通过将模具的底部浸入液氮，使内部凝胶沿轴向进行定向冷冻，冷冻时间为20-40分钟。
  24. 如权利要求12所述的具有Janus特性的复合气凝胶的制备方法，其特征在于：所述步骤d中，冷冻干燥的温度为-70℃～-55℃，真空度为1-3Pa，时间为36-72小时。
  25. 如权利要求12所述的具有Janus特性的复合气凝胶的制备方法，其特征在于：所述步骤e中，所述加热的温度为80-100℃，时间为0.5-3小时。
  26. 一种界面蒸发器，包括权利要求1至25中任一项所述的具有Janus特性的复合气凝胶，其特征在于：所述复合气凝胶具有亲水性的下层(2)吸收水分，为具有疏水性的上层(1)提供水，具有光热转换特性的上层(1)吸收太阳能转化为热能用于蒸发水分。
  27. 如权利要求26所述的界面蒸发器，其特征在于：所述界面蒸发器应用于海水淡化、污水处理或水的蒸发提纯中。
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CN116019141A (zh) * 2023-03-30 2023-04-28 聊城巾帼包装有限公司 纳米纤维素气凝胶抗菌精油缓释体系及其制备方法和应用
CN116425561A (zh) * 2023-03-22 2023-07-14 东华大学 一种3d打印纳米纤维/纳米片陶瓷气凝胶的制备方法

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* Cited by examiner, † Cited by third party
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CN115490285B (zh) * 2022-09-16 2024-04-05 郑州大学 一种巧克力棒状复合太阳能蒸发器及其制备方法与应用
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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103756006A (zh) * 2014-01-20 2014-04-30 东北林业大学 一种超轻、疏水、高吸油率的纳米纤丝化纤维素气凝胶的制备方法
CN109679146A (zh) * 2018-08-31 2019-04-26 中国科学院金属研究所 一种MXene／纤维素复合气凝胶的制备方法
CN110128694A (zh) * 2019-05-13 2019-08-16 浙江工业大学 一种疏水吸油型纤维素基气凝胶的制备方法
CN112321887A (zh) * 2020-09-29 2021-02-05 浙江理工大学 一种润湿性梯度变化机械柔韧纤维素气凝胶的制备方法

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10522732B2 (en) * 2016-05-18 2019-12-31 The Regents Of The University Of California Thermoelectric polymer aerogels and methods of fabrication thereof
CN108862444A (zh) * 2018-06-01 2018-11-23 斌源材料科技（上海）有限公司 光热蒸发复合材料及其制备方法和用途
CN110437496B (zh) * 2019-07-19 2020-10-27 淮阴工学院 一种用于高效水蒸发的聚硅氧烷气凝胶复合材料及其制备方法和应用
CN111116976B (zh) * 2019-12-30 2022-03-04 东华大学 一种纳米纤维气凝胶基太阳能水蒸发器及其制备方法

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103756006A (zh) * 2014-01-20 2014-04-30 东北林业大学 一种超轻、疏水、高吸油率的纳米纤丝化纤维素气凝胶的制备方法
CN109679146A (zh) * 2018-08-31 2019-04-26 中国科学院金属研究所 一种MXene／纤维素复合气凝胶的制备方法
CN110128694A (zh) * 2019-05-13 2019-08-16 浙江工业大学 一种疏水吸油型纤维素基气凝胶的制备方法
CN112321887A (zh) * 2020-09-29 2021-02-05 浙江理工大学 一种润湿性梯度变化机械柔韧纤维素气凝胶的制备方法

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
ZHANG QI, YI GANG, FU ZE, YU HONGTAO, CHEN SHUO, QUAN XIE: "Vertically Aligned Janus MXene-Based Aerogels for Solar Desalination with High Efficiency and Salt Resistance", ACS NANO, AMERICAN CHEMICAL SOCIETY, US, vol. 13, no. 11, 26 November 2019 (2019-11-26), US , pages 13196 - 13207, XP093016609, ISSN: 1936-0851, DOI: 10.1021/acsnano.9b06180 *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116425561A (zh) * 2023-03-22 2023-07-14 东华大学 一种3d打印纳米纤维/纳米片陶瓷气凝胶的制备方法
CN116425561B (zh) * 2023-03-22 2024-02-27 东华大学 一种3d打印纳米纤维/纳米片陶瓷气凝胶的制备方法
CN116019141A (zh) * 2023-03-30 2023-04-28 聊城巾帼包装有限公司 纳米纤维素气凝胶抗菌精油缓释体系及其制备方法和应用

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