A method for preparing biomimetic polyarylene ether aerogel material for solar water evaporation

Abstract

This invention belongs to the field of aerogel technology and discloses a method for preparing a biomimetic polyarylene ether aerogel material for solar water evaporation. The method involves dissolving carboxylated chitosan in deionized water, and preparing a biomimetic three-dimensional network porous wet gel through hydrogen bonding and electrostatic interactions between the chitosan and sulfonated polyarylene ether material and MXene. The resulting wet gel is then directionally frozen and freeze-dried to obtain the aerogel material. The aerogel material prepared by this invention exhibits excellent photothermal, thermal insulation, and water evaporation properties. Furthermore, the aerogel possesses a certain degree of flexibility and compressive strength, showing great promise for applications in seawater desalination and wastewater purification.

Description

Technical Field

[0001] This invention belongs to the field of aerogel technology and relates to a method for preparing a biomimetic biogel material, specifically a method for preparing a biomimetic polyarylene ether aerogel material for solar water evaporation. Background Technology

[0002] Rapid population growth is driving demand for freshwater, creating an urgent need to develop viable clean water production methods. Global climate change is an urgent issue, and replacing traditional energy sources with renewable energy has become an irreversible trend. Interface solar vapor generation (SVG) is gradually emerging as a compelling innovative strategy for sustainable water resource management, using inexhaustible solar energy as its sole power source, thus avoiding the fierce competition associated with exploiting non-renewable resources.

[0003] To fully utilize solar energy and improve water vapor generation efficiency, according to Arunkumar T, Lee SJ. A review on carbonized natural green flora for solar desalination [J]. Renewable & Sustainable Energy Reviews, 2022, 158, 112121., many excellent solar energy absorbing materials have been developed, including plasma-heated metallic materials, non-radiative relaxation semiconductor materials, molecularly thermally vibrating carbon materials, and organic polymers. MXene, as a new class of transition metal compounds, has excellent visible light absorption characteristics and a photothermal conversion efficiency close to 100%. However, its weak light absorption in the ultraviolet and near-infrared regions limits its application. Therefore, combining the active groups on the MXene surface with other photothermal materials is key to achieving broadband and efficient solar energy absorption. Furthermore, the structural design of the solar interfacial evaporator and the appropriate selection of the substrate material are crucial. According to Zhang HM, Kim JK. Integrated Water and Thermal Managements in Bioinspired Hierarchical MXene Aerogels for Highly Efficient Solar-Powered Water Evaporation[J]. Advanced Functional Materials, 2022, 32(19), 2111794., water evaporation efficiency can be improved by introducing functional groups to reduce the enthalpy of evaporation, designing vertical through-hole structures to promote rapid water transport, and adding additional insulating foam to the periphery to minimize heat loss. However, the structures constructed under water and thermal management strategies are independent, and so far, existing technologies cannot simultaneously meet the requirements of rapid water transport and reduced heat loss. Therefore, the design of a reasonable evaporator structure remains very challenging.

[0004] The strategy of this invention is to sulfonate a polyarylene material composed of rigid phenyl groups and flexible oxygen or thioether bonds, and construct a unique biomimetic eagle feather structure with carboxylated chitosan through hydrogen bonding and electrostatic interactions, thereby achieving rapid water transport and reducing heat loss. Due to the excellent light absorption capacity brought by the highly conjugated π bonds and π-π stacked aromatic units of the polyarylene material, the absorption rate of sunlight across the entire wavelength can be improved through synergistic effects with MXene, ultimately achieving efficient solar-driven seawater evaporation and wastewater purification. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing a biomimetic polyarylene ether aerogel material for solar water evaporation. This invention provides a method for preparing a biomimetic aerogel material by crosslinking carboxylated chitosan as the aerogel framework, sulfonated polyarylene ether material as the crosslinking hard segment, and MXene as the photothermal material through hydrogen bonding and electrostatic interactions.

[0006] To achieve the above-mentioned objectives, the technical solution of this invention is as follows:

[0007] A method for preparing a biomimetic polyarylene ether aerogel material for solar water evaporation, comprising the following steps:

[0008] (1) Carboxylated chitosan and sulfonated polyarylene ether material (sulfonation degree DS of 1.20-1.65) were dissolved in deionized water to obtain a mixed solution of carboxylated chitosan / sulfonated polyarylene ether; the mixture was added at a mass ratio of carboxylated chitosan: sulfonated polyarylene ether: deionized water of 1:0.1-0.3:50-100; then, Ti3C2T obtained by ultrasonic treatment was added. x A single-layer nanosheet dispersion was added to a mixed solution of carboxylated chitosan / sulfonated polyarylene ether and continuously stirred magnetically at 25°C for 1 hour; then the mixed solution was poured into a mold to obtain a composite wet gel.

[0009] (2) The composite wet gel in step (1) is subjected to liquid nitrogen directional freezing and freeze-drying to obtain aerogel material: the composite wet gel is frozen by liquid nitrogen for 10 to 40 minutes; the freeze-drying conditions are -50℃, 10Pa, and 72h.

[0010] The feed ratio in step (1) is: carboxylated chitosan: sulfonated polyarylene ether: Ti3C2T x Single-layer nanosheets: deionized water ratio is 1:0.1~0.3:0.005~0.02:50~100, and the optimal degree of sulfonation of the polyarylene ether used is DS 1.65.

[0011] The sulfonated polyarylether materials in step (1) include polyarylether sulfone, polyarylether ketone, naphthalenebiphenyl polyarylether sulfone, naphthalenebiphenyl polyarylether ketone, naphthalenebiphenyl polyarylether sulfone ketone, and naphthalenebiphenyl polyarylether nitrile ketone, with the following specific structures:

[0012]

[0013] Ar1 and Ar3 are the main structures of the dihalogenated monomers. Ar1 and Ar3 may be the same or different, and can be any one or more of the following structures:

[0014]

[0015] Ar2 is the main structure of the bisphenol monomer, and it is any one or more of the following structures:

[0016]

[0017] R1, R2, R3, and R4 are hydrogen, halogen substituents, phenyl, phenoxy, straight-chain alkyl containing at least one carbon atom, branched alkyl containing at least one carbon atom, or branched alkoxy containing at least one carbon atom. The structures of R1, R2, R3, and R4 may be the same or different.

[0018] The aerogel prepared by this invention has a density of 32.8 mg / cm³. 3 The water evaporation rate at 1 solar irradiance is 2.34 kg / m³. 2 h, with an energy efficiency of 91.7%.

[0019] The beneficial effects of this invention are as follows: Compared with existing technologies, this invention provides a novel approach to preparing biomimetic aerogels for efficient solar water evaporation. Specifically, it achieves cross-linking through hydrogen bonds and electrostatic interactions between amino, hydroxyl, and sulfonic acid groups, and uses directional freezing technology to prepare a three-dimensional porous network aerogel. The preparation process is relatively simple, and the resulting aerogel material has low density and thermal conductivity. The synergistic effect between polyarylene ether and MXene improves the absorption rate of solar energy across the entire wavelength range, and the biomimetic feather structure endows the aerogel with excellent thermal insulation and water evaporation properties, showing broad application prospects in seawater desalination and wastewater purification. Attached Figure Description

[0020] Figure 1 This is a scanning electron microscope image of the aerogel prepared in Example 1.

[0021] Figure 2 This is a scanning electron microscope image of the aerogel prepared in Comparative Example 1.

[0022] Figure 3 This is a scanning electron microscope image of the aerogel prepared in Comparative Example 2. Detailed Implementation

[0023] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and technical solutions.

[0024] Example 1

[0025] This embodiment provides a biomimetic gel material, the preparation method of which includes the following steps:

[0026] (1) Weigh 2g of carboxylated chitosan and dissolve it in 100mL of deionized water. Stir at room temperature for 20min to obtain a precursor solution. Then add 0.2-0.6g of sulfonated polyarylene ether to the precursor solution. Then add 0.01-0.04g of ultrasonically treated MXene dispersion to the mixed solution. Stir magnetically at 25℃ for 1 hour and pour the mixed solution into a polytetrafluoroethylene square mold to obtain a wet gel.

[0027] (2) Cover the mold in step (1) with a metal container filled with liquid nitrogen, freeze it with liquid nitrogen for 10 to 40 minutes, and then freeze-dry it at -50°C, pressure of 10 Pa, and drying time of 72 hours to make a composite aerogel.

[0028] To explore the optimal preparation process of the aerogel of this invention, 2g of carboxylated chitosan was used as raw material, and other conditions were kept constant. The amount of sulfonated polyarylene ether and MXene and the directional freezing time were changed respectively.

[0029]

[0030]

[0031]

[0032] Based on the actual gel solution dispersion and aerogel forming effect, the optimal dosage of sulfonated polyarylene ether material is carboxylated chitosan: sulfonated polyarylene ether = 1:0.2; the optimal MXene addition is carboxylated chitosan: MXene = 1:0.01; and the optimal directional freezing time is 30 min.

[0033] See Figure 1 The image shows a scanning electron microscope image of the aerogel prepared in Example 1. It was found that the aerogel made by adding sulfonated polyarylether material through directional freezing technology has a radial structure that mimics eagle down feathers, which is also the reason for the low thermal conductivity and good mechanical properties of the aerogel.

[0034] Comparative Example 1

[0035] This comparative example provides an aerogel material, the preparation method of which includes the following steps:

[0036] (1) Weigh 2g of carboxylated chitosan and dissolve it in 100mL of deionized water. Stir at room temperature for 20min to obtain a precursor solution. Then add 0.4g of sulfonated polyarylene ether to the precursor solution. Add 0.02g of ultrasonically treated MXene dispersion to the mixed solution. Stir magnetically at 25℃ for 1 hour and pour the mixed solution into a polytetrafluoroethylene square mold to obtain a wet gel.

[0037] (2) After freezing the mold in step (1) in a freezer, freeze-dry it at a pressure of 10 Pa for 72 hours to make a composite aerogel.

[0038] See Figure 2 The scanning electron microscope image of the aerogel prepared in Comparative Example 1 shows that the aerogel prepared by direct freeze-drying in a freezer has a disordered three-dimensional network structure, which is the reason for the poor heat insulation and water evaporation performance of the aerogel.

[0039] Comparative Example 2

[0040] This comparative example provides an aerogel material, the preparation method of which includes the following steps:

[0041] (1) Weigh 2g of carboxylated chitosan and dissolve it in 100mL of deionized water. Stir at room temperature for 20min. Then add 0.02g of MXene dispersion after ultrasonic treatment to the mixed solution. Stir magnetically at 25℃ for 1 hour and pour the mixed solution into a polytetrafluoroethylene square mold to obtain wet gel.

[0042] (2) Cover the mold in step (1) with a metal container filled with liquid nitrogen, freeze it with liquid nitrogen for 30 minutes and then freeze-dry it at a pressure of 10 Pa for 72 hours to make a composite aerogel.

[0043] See Figure 3 The scanning electron microscope image of the aerogel prepared in Comparative Example 2 shows that the carboxylated chitosan / MXene aerogel prepared by directional freezing technology without the addition of sulfonated polyarylether material has a smooth and flat radial surface structure, which is also the reason for the relatively poor thermal insulation and mechanical properties of this aerogel.

[0044] Application Example 1

[0045] Taking sulfonated naphthalene biphenyl polyarylene ether sulfone ketone (SPPESK) as an example, the selection process for the optimal dosage of SPPESK is as follows:

[0046] 2g of carboxylated chitosan was dissolved in deionized water, and different proportions (10%, 20%, and 30%) of SPPESK (based on the mass of carboxylated chitosan) were added. Then, 0.02g of MXene dispersion was added. Aerogel materials were prepared according to the above method, and the mechanical properties and water evaporation properties of the aerogel were tested.

[0047]

[0048] As shown in the table, when the amount of SPPESK added exceeds 20%, the mixed solution will rapidly gel, resulting in uneven stirring. Furthermore, it was found that the compressibility and water evaporation properties of the aerogel significantly improve with increasing SPPESK dosage. Therefore, this invention selects an optimal SPPESK addition of 20%, achieving a water evaporation rate as high as 2.34 kg / m³ under a given solar irradiance. 2 h.

[0049] Application Example 2

[0050] The aerogel properties of Example 1 and Comparative Examples 1 and 2 under the three preparation processes were compared, and the results are as follows:

[0051]

[0052] As shown in the table, the preparation process in Example 1, which involves adding sulfonated polyarylene ether material and using directional freezing technology to prepare biomimetic gel, exhibits the best mechanical properties, thermal insulation properties, and water evaporation properties.

Claims

1. A method for preparing a biomimetic polyarylene ether aerogel material for solar water evaporation, characterized in that, The steps are as follows: (1) Carboxylated chitosan and sulfonated polyarylene ether material were dissolved in deionized water to obtain a mixed solution of carboxylated chitosan / sulfonated polyarylene ether; then, Ti3C2T obtained by ultrasonic treatment was... x A single-layer nanosheet dispersion was added to a mixed solution of carboxylated chitosan / sulfonated polyarylene ether and continuously stirred magnetically at 25°C for 1 hour; then the mixed solution was poured into a mold to obtain a composite wet gel. (2) The composite wet gel in step (1) is subjected to liquid nitrogen directional freezing and freeze-drying to obtain aerogel material: the composite wet gel is frozen by liquid nitrogen for 10 to 40 minutes; the freeze-drying conditions are -50℃, 10Pa, and 72h.

2. The preparation method according to claim 1, characterized in that, The weight ratio of the reactants in step (1) is carboxylated chitosan: sulfonated polyarylene ether: Ti3C2T x Single-layer nanosheets: deionized water ratio is 1:0.1~0.3:0.005~0.02:50~100.

3. The preparation method according to claim 1, characterized in that, The polyarylene ether materials in step (1) include polyarylene ether sulfone, polyarylene ether ketone, naphthalene-biphenyl polyarylene ether sulfone, naphthalene-biphenyl polyarylene ether ketone, naphthalene-biphenyl polyarylene ether sulfone ketone, and naphthalene-biphenyl polyarylene ether nitrile ketone, with the following specific structures: Ar1 and Ar3 are the main structures of the dihalogenated monomers. Ar1 and Ar3 may be the same or different, and may be any one or more of the following structures: Ar2 is the main structure of the bisphenol monomer, which is any one or a combination of two or more of the following structures: R1, R2, R3, and R4 are hydrogen, halogen substituents, phenyl, phenoxy, straight-chain alkyl containing at least one carbon atom, branched alkyl containing at least one carbon atom, or branched alkoxy containing at least one carbon atom. The structures of R1, R2, R3, and R4 may be the same or different.

4. The preparation method according to claim 1, characterized in that, The degree of sulfonation (DS) of sulfonated polyarylether materials is 1.20–1.65.

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