Conjugated microporous polymers based on terephthalaldehyde, preparation methods and applications

Abstract

This invention discloses a conjugated microporous polymer based on terephthalaldehyde, its preparation method, and its applications, relating to the technical fields of seawater desalination materials and wastewater purification materials. It aims to overcome the technical problem of low photothermal conversion efficiency in existing technologies. The structural formula of the conjugated microporous polymer based on terephthalaldehyde is as follows: [Structure formula would be inserted here]. This invention can provide an efficient, stable, and low-cost solution for seawater desalination and wastewater purification.

Description

Technical Field

[0001] This invention relates to the technical fields of seawater desalination materials and wastewater purification materials. More specifically, this invention relates to a conjugated microporous polymer based on terephthalaldehyde, its preparation method, and its applications. Background Technology

[0002] With the global water shortage and pollution problem becoming increasingly prominent, seawater desalination and sewage purification have become key means to alleviate the water crisis. Photothermal-driven interfacial evaporation technology has become a research hotspot in this field due to its green and efficient nature, and its core performance is highly dependent on the comprehensive quality of photothermal materials.

[0003] While some progress has been made in photothermal materials, several technical bottlenecks remain to be addressed: some materials have limited light absorption ranges, making it difficult to fully utilize the full spectrum of solar energy; their photothermal conversion efficiency is low, failing to meet the demands of efficient evaporation; the preparation process often relies on metal catalysts, increasing costs and potentially leading to residual impurities in the products; simultaneously, most materials suffer from insufficient chemical and thermal stability, or have poor pore structure design, inadequate water transport capacity, or poor hydrophilicity, hindering their long-term application in complex water treatment scenarios. Furthermore, some materials are prone to instability under extreme conditions such as high salinity, acidity, and alkali, further limiting their practical industrial application.

[0004] Therefore, it is necessary to design a technical solution that can overcome the above-mentioned defects. Summary of the Invention

[0005] One object of the present invention is to provide a conjugated microporous polymer (CMP) based on terephthalaldehyde, its preparation method and application, which provides an efficient, stable and low-cost solution for seawater desalination and wastewater purification.

[0006] To achieve these objectives and other advantages of the present invention, according to one aspect of the present invention, a conjugated microporous polymer based on terephthalaldehyde is provided, the structural formula of which is as follows:

[0007] .

[0008] According to another aspect of the present invention, a method for preparing a conjugated microporous polymer based on terephthalaldehyde is also provided, comprising: mixing 2,2',6,6'-tetramethyl-4,4'-bipyranide, terephthalaldehyde, benzoic anhydride and benzoic acid in a container, flash-freezing in a liquid nitrogen bath, degassing under vacuum and sealing the container, and reacting at 170-190°C for 2-4 days; after the reaction, soaking the blocky monomer in acetone for 20-30 hours, crushing it into powder, washing it sequentially with acetone and tetrahydrofuran, and performing Soxhlet extraction with tetrahydrofuran for 20-30 hours, and finally vacuum drying at 75-85°C for 10-14 hours to obtain a conjugated microporous polymer based on terephthalaldehyde.

[0009] Furthermore, the molar ratio of 2,2',6,6'-tetramethyl-4,4'-bipyranide, terephthalaldehyde, benzoic anhydride, and benzoic acid is 1:(1.8-2.2):(1.8-2.2):(0.18-0.22).

[0010] According to another aspect of the invention, a gel composite material is also provided, comprising the aforementioned terephthalaldehyde-based conjugated microporous polymer and polyvinyl alcohol.

[0011] Furthermore, the mass ratio of the conjugated microporous polymer based on terephthalaldehyde to polyvinyl alcohol is (0.01-0.02):1.

[0012] According to another aspect of the invention, the application of conjugated microporous polymers based on terephthalaldehyde in the preparation of photothermal conversion materials is also provided.

[0013] According to another aspect of the invention, the application of conjugated microporous polymers or gel composites based on terephthalaldehyde in seawater desalination is also provided.

[0014] According to another aspect of the invention, the application of conjugated microporous polymers or gel composites based on terephthalaldehyde in wastewater purification is also provided.

[0015] The present invention has at least the following beneficial effects:

[0016] The conjugated microporous polymer (DP-CMP1) based on terephthalaldehyde and its gel composite material (PVA+DP-CMP1) of this application have significant technical advantages. DP-CMP1 has obvious microporous characteristics and a high specific surface area (BET specific surface area of ​​841 m²). 2 With a pore size distribution ranging from 0.5 to 2.1 nm, PVA+DP-CMP1 exhibits excellent photothermal conversion performance. Under 660 nm laser irradiation, the temperature of DP-CMP1 increased from 29.1 °C to 174.7 °C within 4 seconds. The water evaporation rate of PVA+DP-CMP1 under one sun reached 3.83 kg / m³. −2 h −1It boasts a solar energy conversion efficiency of up to 97.5%, far exceeding existing organic photothermal materials. It exhibits extremely high stability, with a thermal stability temperature reaching 400℃. It is resistant to complex environments such as acids, alkalis, and organic solvents. Even after multiple heating-cooling cycles and water treatment cycles, its structure, morphology, and performance remain stable, and no salt accumulation occurs during seawater desalination. Its water treatment effect is significant, reducing sodium content after desalination. + K + The plasma concentration is reduced by four orders of magnitude, meeting WHO drinking water standards; it can efficiently remove Cu. 2+ Zn 2+ It exhibits excellent purification effects against heavy metals and organic pollutants. The preparation process requires no metal catalyst, keeping costs under control. The gel composite material combines good hydrophilicity, low thermal conductivity, and water transport capacity, achieving a daily water production of 21.1 kg m³ for outdoor applications. −2 This provides an efficient, stable, and low-cost solution for seawater desalination and wastewater purification.

[0017] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0018] Figure 1 The Fourier transform infrared spectra of (a) the model compound (MC) and its monomer (DP) are shown; (b) the model compound (MC) in CDCl3. 13 C nuclear magnetic resonance spectrum.

[0019] Figure 2 The pore size distribution of DP-CMP1 is shown, indicating that DP-CMP1 mainly exhibits an ultramicropore distribution, which is beneficial for the adsorption and transport of water molecules.

[0020] Figure 3 The powder X-ray diffraction pattern of DP-CMP1 is shown. No strong diffraction peaks are observed, indicating its amorphous properties.

[0021] Figure 4 Field emission scanning electron microscopy (FE-SEM) images of the DP-CMP1 are shown.

[0022] Figure 5 The thermogravimetric analysis (TGA) spectrum of DP-CMP1 is shown.

[0023] Figure 6 The Fourier transform infrared spectra of DP-CMP1 after immersion in different solvents are shown.

[0024] Figure 7 The water contact angle of the DP-CMP1 is shown.

[0025] Figure 8The model compound (MC) of 20 mg was shown to be effective under a 660 nm laser (100 mW•cm). -2 Photothermal images under illumination.

[0026] Figure 9 This shows (a) DP-CMP1 under 660 nm laser (100 mW·cm) conditions. -2 (a) Photothermal image under irradiation. (b) Photothermal conversion behavior of DP-CMP1 powder under irradiation with 660 nm lasers of different powers. (c) Anti-photobleaching properties of DP-CMP1 during six heating-cooling cycles.

[0027] Figure 10 The following are shown: (a) Fourier transform infrared spectra of DP-CMP1 before and after six heating-cooling cycles; (b) Scanning electron microscope images of DP-CMP1 before and after six heating-cooling cycles; (c) Absorption spectra of DP-CMP1 before and after six heating-cooling cycles.

[0028] Figure 11 Digital photographs of polyvinyl alcohol (PVA) (a) and PVA+DP-CMP1 (1.5 wt%) (b) are shown; scanning electron microscope images of polyvinyl alcohol (PVA) (c) and PVA+DP-CMP1 (1.5 wt%) (d) are shown.

[0029] Figure 12 A schematic diagram of a solar steam generation device is shown.

[0030] Figure 13 The evaporation performance of PVA+DP-CMP1 (1.5 wt%) in acidic and alkaline aqueous solutions is shown.

[0031] Figure 14 The following are shown: (a) Evaporation performance of PVA+DP-CMP1 (1.5 wt%) under different light intensities; (b) Temperature variation of PVA+DP-CMP1 (1.5 wt%) under different light intensities.

[0032] Figure 15 The images show PVA+DP-CMP1 (1.5 wt%) before (a) and after (b) ten evaporation cycles in pure water.

[0033] Figure 16 The curves showing the change in water collection over time for polyvinyl alcohol (PVA) composite gels with different DP-CMP1 loadings are presented.

[0034] Figure 17 The results show that PVA+DP-CMP1 (1.5 wt%) at 100 mW•cm -2 Simulated seawater evaporation curve under sunlight.

[0035] Figure 18 The long-term stability of the evaporation performance of PVA+DP-CMP1 (1.5 wt%) in seawater was demonstrated.

[0036] Figure 19 The images show PVA+DP-CMP1 (1.5 wt%) before (a) and after ten evaporation cycles in seawater (b).

[0037] Figure 20 The evaporation rates of PVA+DP-CMP1 (1.5 wt%) in pure water, 3.5 wt%, 5 wt%, and 10 wt% sodium chloride (NaCl) solutions (AM 1.5G) are shown.

[0038] Figure 21 The x-axis represents energy (eV), and the y-axis represents (Ahν). 2 The Tauc curves of DP-CMP1 and the model compound (MC) are shown (product of absorbance and photon energy). The band gaps of the two compounds are calculated to be 1.30 eV and 1.82 eV, respectively, by linear fitting.

[0039] Figure 22 The x-axis represents time (s) and the y-axis represents transient current (A), recording the transient current response curve of DP-CMP1 under intermittent illumination conditions.

[0040] Figure 23 The horizontal axis represents the real part of the impedance Z'(ohm), and the vertical axis represents the negative value of the imaginary part of the impedance - Z''(ohm), showing the electrochemical impedance spectroscopy (EIS) of DP-CMP1.

[0041] Figure 24 The x-axis represents the types of metal ions (Na). 2+ K + Mg 2+ Ca 2+ The vertical axis represents ion concentration, showing the main ions (Na+, Na ... 2+ K + Mg 2+ Ca 2+ The concentration change of ).

[0042] Figure 25 The results show the heavy metal ions (Cu) before and after purification with PVA+DP-CMP1 (1.5 wt%). 2+ Ni 2+ Zn 2+ Ag + Concentration changes. Detailed Implementation

[0043] The present invention will now be described in further detail so that those skilled in the art can implement it based on the description.

[0044] It should be understood that terms such as "having," "comprising," and "including" used in the embodiments of this application do not exclude the presence or addition of one or more other elements or combinations thereof. All directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationship and movement of components in a specific posture. If the specific posture changes, the directional indication will also change accordingly. When an element is referred to as "fixed to" or "set on" another element, it can be directly on the other element or may have an intervening element present. When an element is referred to as "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element through an intervening element. Descriptions involving "first," "second," etc., in the embodiments of this application are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features.

[0045] It should be noted that the technical solutions of the various embodiments of this application can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this application.

[0046] Embodiments of this application provide conjugated microporous polymers based on terephthalaldehyde, the structural formula of which is as follows:

[0047] .

[0048] The core characteristic of the conjugated microporous polymer based on terephthalaldehyde is its core building block: 2,2',6,6'-tetramethyl-4,4'-bipyran subunit (TMDP), forming a fully conjugated framework structure through vinylidene and aromatic rings. The TMDP-derived bispyran subunits are linked by racemic carbon-carbon double bonds, forming a highly extended π-conjugated system, which is crucial for the polymer's broad-spectrum light absorption and efficient photothermal conversion. The vinylidene connecting unit not only extends the conjugated chain length but also enhances the chemical stability of the framework, preventing bond breakage under light or acid / alkali conditions. The polymer's microporous characteristic refers to its ultramicroporous structure with pore sizes ranging from 0.5 to 2.1 nm. This pore size ensures rapid adsorption and transport of water molecules and enhances the interaction between light and matter through its high specific surface area. The polymer is a black solid powder, insoluble in common solvents such as water, tetrahydrofuran, and dichloromethane. Its structure can be visualized through solid... 13 C CP-MAS NMR (characteristic C=C peaks at 117 ppm and 134 ppm), FT-IR (1590 cm⁻¹) -1 and 1007 cm -1 The C=C stretching peak at the point of origin clearly indicates that the above structural features together endow the polymer with excellent photothermal properties, thermal stability (resistant to 400℃) and chemical stability.

[0049] The embodiments of this application provide a method for preparing a conjugated microporous polymer based on terephthalaldehyde, comprising: mixing 2,2',6,6'-tetramethyl-4,4'-bipyranide, terephthalaldehyde, benzoic anhydride and benzoic acid in a container, flash-freezing in a liquid nitrogen bath, degassing under vacuum and sealing the container, and reacting at 170-190°C for 2-4 days; after the reaction, soaking the blocky monomer in acetone for 20-30 hours, crushing it into powder, washing it sequentially with acetone and tetrahydrofuran, and extracting it with tetrahydrofuran using a Soxhlet extracter for 20-30 hours, and finally vacuum drying it at 75-85°C for 10-14 hours to obtain a conjugated microporous polymer based on terephthalaldehyde.

[0050] The core of the preparation method of the conjugated microporous polymer in this embodiment lies in constructing the target product through a metal-free aldol polycondensation reaction. Each step is a necessary technical means to achieve high purity and high yield. After mixing, the raw materials are flash-frozen in a liquid nitrogen bath (77K) and degassed under vacuum to completely remove oxygen and moisture from the system, avoiding the inhibitory effect of oxygen on the conjugated polymerization reaction and the side reactions initiated by moisture, ensuring the directional progress of the polycondensation reaction. A sealed container maintains an inert environment for the reaction system, preventing air from re-entering during the reaction. The reaction temperature range of 170-190℃ is determined based on the balance between reaction efficiency and product purity. Below 170℃, the aldol polycondensation reaction rate is too slow, resulting in insufficient monomer conversion; above 190℃, monomer decomposition or excessive cross-linking is likely to occur, leading to damage to the product's pore structure. 180℃ is the optimal reaction temperature, and this temperature range can cover process fluctuations in practical applications. The reaction time of 2-4 days ensures that TMDP and terephthalaldehyde undergo sufficient polycondensation to form a complete conjugated framework. The reaction product is soaked in acetone for 20-30 hours to soften the blocky polymer, facilitating subsequent crushing and grinding. Washing with acetone and tetrahydrofuran sequentially removes unreacted monomers, benzoic anhydride, and other soluble impurities. Soxhlet extraction with tetrahydrofuran for 20-30 hours deeply removes trace impurities encapsulated within the polymer micropores, ensuring the polymer's pore structure and photothermal properties. Vacuum drying at 75-85℃ for 10-14 hours completely removes residual solvents while avoiding polymer thermal decomposition, yielding a dry and pure target product.

[0051] In another embodiment, the molar ratio of 2,2',6,6'-tetramethyl-4,4'-bipyranide, terephthalaldehyde, benzoic anhydride and benzoic acid is 1:(1.8-2.2):(1.8-2.2):(0.18-0.22).

[0052] The molar ratio of terephthalaldehyde to TMDP is 1.8-2.2:1. A slight excess of terephthalaldehyde ensures complete reaction of TMDP, the core monomer, avoiding insufficient polymer conjugation due to TMDP residue. The excess ratio is controlled at 0.8-1.2 times to prevent the formation of byproducts from excessive terephthalaldehyde polymerization, which could affect the polymer's pore structure. The molar ratio of benzoic anhydride to terephthalaldehyde remains consistent (1.8-2.2:1). Benzoic anhydride acts as a promoter of the polycondensation reaction and also reacts with the water generated in the reaction, maintaining a dehydration environment and promoting the forward polycondensation of aldol. Matching its dosage with that of terephthalaldehyde ensures reaction efficiency. The molar ratio of benzoic acid to TMDP is 0.18-0.22:1. When the amount of benzoic acid used as a catalyst is too low, the catalytic efficiency is insufficient and the reaction rate is slow; when the amount is too high, it will remain in the product, affecting the photothermal conversion efficiency and chemical stability of the polymer. This ratio range can achieve a balance between catalytic efficiency and product purity.

[0053] Embodiments of this application also provide gel composite materials comprising the aforementioned terephthalaldehyde-based conjugated microporous polymer and polyvinyl alcohol.

[0054] For example, the composite material is made by in-situ co-gelling of the aforementioned conjugated microporous polymer (CMP) and polyvinyl alcohol (PVA). This composition design is key to achieving efficient photothermal evaporation. PVA, as the composite carrier, preferably has an average molecular weight of 15,000. PVA with this molecular weight possesses good gelling properties, hydrophilicity, and mechanical strength, enabling it to form a continuous porous network structure that provides channels for water molecule transport. Simultaneously, PVA has extremely low thermal conductivity, reducing the transfer of heat generated during photothermal conversion to the water body, achieving heat localization, and improving evaporation efficiency. The conjugated microporous polymer (CMP), as the photothermal functional component, is uniformly dispersed within the porous network of PVA. Its broad-spectrum light absorption (300-2000 nm) and efficient photothermal conversion capability are core to the composite material's ability to utilize solar energy. The composite of CMP and PVA is not a simple mixing process, but rather an in-situ co-gelling method that embeds CMP into the PVA framework, preventing CMP detachment during use and ensuring the long-term stability of the composite material. The composite material is a black, homogeneous gel that retains the porous structure of PVA (which facilitates water transport) and the photothermal properties of CMP. Its structure can be observed by SEM, showing that CMP is uniformly dispersed in the PVA matrix. UV-Vis-NIR spectroscopy shows that its light absorption performance is significantly better than that of pure PVA.

[0055] In another embodiment, the mass ratio of the conjugated microporous polymer based on terephthalaldehyde to polyvinyl alcohol is (0.01-0.02):1.

[0056] The lower limit of the CMP ratio is 0.01:1 (i.e., 1 wt%). When the CMP content is below this ratio, the light absorption intensity of the composite material is insufficient, making it unable to effectively capture solar energy and convert it into heat energy, resulting in a significant decrease in the water evaporation rate and making it difficult to meet the requirements for efficient evaporation. The upper limit of the CMP ratio is 0.02:1 (i.e., 2 wt%). When the CMP content is above this ratio, excessive CMP will block the porous network structure of PVA, increase the resistance to water molecule transport, and destroy the gel integrity of PVA, leading to a decrease in the evaporation rate. Within this range, the composite material can achieve efficient photothermal conversion through CMP and ensure rapid water transport through the porous structure of PVA, achieving a balance between evaporation rate and stability.

[0057] The embodiments of this application provide the application of conjugated microporous polymers based on terephthalaldehyde in the preparation of photothermal conversion materials.

[0058] This polymer exhibits strong absorption in the 300-2000 nm range, which can fully utilize the ultraviolet, visible, and near-infrared spectra of solar energy, solving the problem of narrow light absorption range in existing materials and improving solar energy utilization efficiency; it can also withstand 660 nm laser (100 mW / cm²) light. -2 Under simulated sunlight (1 kW m³), ​​the temperature can rise from room temperature to 174.7℃ within 4 seconds. -2 Under these conditions, the composite material, when combined with PVA, still achieves a solar-driven water evaporation efficiency of 97.5%, demonstrating superior photothermal conversion performance compared to existing organic photothermal materials. Furthermore, its thermal stability temperature reaches 400℃, and it is resistant to 6 M HCl, 6 M NaOH, and common organic solvents. After six heating-cooling cycles, its light absorption performance, morphology, and structure show no significant changes, indicating long-term reliability and solving the problems of easy photobleaching and poor stability in existing photothermal materials. The application's protection scope covers all photothermal conversion materials with this conjugated microporous polymer as the core functional component, including but not limited to powder, film, and composite material forms, suitable for various photothermal utilization scenarios such as solar heating, photothermal catalysis, and photothermal evaporation.

[0059] Embodiments of this application also provide the application of conjugated microporous polymers or gel composites based on terephthalaldehyde in seawater desalination.

[0060] Under one day of solar irradiation, the seawater evaporation rate of the gel composite material reached 3.77 kg m³. -2 h -1 (DP-CMP1 base), daily water production reaches 21.1 kg m³ under outdoor conditions. -2 This material efficiently converts seawater into water vapor, solving the problems of low efficiency and high energy consumption in existing desalination technologies. Through photothermal-driven interfacial evaporation, salt ions are retained in the original solution during the seawater evaporation process, reducing the ion concentration in the purified water by four orders of magnitude, fully meeting WHO drinking water standards. It maintains a stable evaporation rate even in high-salt solutions of 3.5-10 wt%, without salt accumulation. The material is resistant to acids, alkalis, and high salt concentrations. After ten cycles of use in actual seawater (deep-sea water from Qingdao), the evaporation rate showed no significant decrease, and the structure remained intact, demonstrating its adaptability to the complex working conditions of the marine environment and solving the problems of susceptibility to salt corrosion and poor stability of existing desalination materials. The application's protection scope covers all seawater desalination technologies using this conjugated microporous polymer or gel composite material, including laboratory-scale, outdoor emergency, and industrial applications, providing a novel solution for seawater desalination.

[0061] Embodiments of this application also provide the application of conjugated microporous polymers or gel composites based on terephthalaldehyde in wastewater purification.

[0062] For Cu 2+ Zn 2+ Ni2+ Ag + For wastewater containing heavy metal ions, the material converts water into water vapor through photothermal evaporation. Heavy metal ions are trapped because they cannot evaporate with the water vapor. After purification, the concentration of heavy metal ions in the water is reduced to below 0.01 ppm, with a removal rate exceeding 99.99%, meeting the standards for heavy metal content in drinking water. For wastewater containing organic pollutants such as methyl orange (MO), rhodamine B (RB), and methylene blue (MB), the organic pollutants are trapped in the original liquid during evaporation. The UV-Vis spectrum of the condensate shows no characteristic absorption peaks of pollutants, and the transmittance reaches 99.5%, achieving efficient separation of organic pollutants. For complex wastewater where heavy metal ions and organic pollutants coexist, the material is expected to maintain a stable purification effect. Simultaneously, the material has good mechanical strength, facilitating recycling and reuse in practical applications. The application's protection scope covers purification scenarios for various types of wastewater (heavy metal wastewater, organic pollutant wastewater, and combined pollutant wastewater). Its purification mechanism is based on "photothermal evaporation-pollutant trapping," requiring no additional chemical agents, making it green and environmentally friendly, and solving the problems of high cost and secondary pollution associated with existing wastewater purification technologies.

[0063] The following is a description of a specific embodiment.

[0064] Terms and definitions:

[0065] Nuclear magnetic resonance (NMR) spectrum: 1 HNMR spectra were determined on a Bruker Avance III-400 NMR spectrometer. Chemical shifts (δ, unit: ppm) were determined using solvent residual protons as the standard. Solid state 13 C-cross polarization magic angle rotation (CP / MAS) NMR measurements were performed on a Bruker Avance III 400WB NMR spectrometer with a magic angle rotation rate of 5 kHz and a cross polarization contact time of 2 ms.

[0066] Solid-state UV-Vis (UV / Vis) spectrum: Solid-state UV-Vis spectra were measured on a Shimadzu U-4100 spectrophotometer, with a wavelength range of 200-800 nm.

[0067] Ultraviolet-visible-near-infrared (UV-vis-NIR) spectra: Absorption spectra were monitored using a Lambda 950 UV-visible-near-infrared spectrophotometer. Fourier transform infrared (FTIR) spectra were acquired using a Bruker TENSOR 27 infrared spectrometer.

[0068] Infrared spectroscopy: Infrared spectra were measured using a Nicolet Avatar FT-IR360 infrared spectrometer, with a test range of 500-4000 cm⁻¹. -1 The potassium bromide (KBr) tableting method was used.

[0069] Powder X-ray diffraction (PXRD): Powder X-ray diffraction data were measured on a Panaco Empyrean X-ray diffractometer. The powder sample was placed on a glass substrate. The test range was 2θ = 1.5-45° with a step size of 0.02° and a test temperature of 25°C.

[0070] Thermogravimetric analysis (TGA): Thermogravimetric analysis was performed on a TAQ500 thermogravimetric analyzer under a nitrogen atmosphere at a temperature of 10 °C / min. -1 The heating rate was measured from room temperature to 800°C, and the analysis was performed by measuring the mass loss.

[0071] Nitrogen adsorption-desorption isotherms: Nitrogen adsorption-desorption isotherms were measured at 77 K using a McMurray Adsorption Analyzer ASAP2020. Specific surface area and pore volume were calculated using the Brunol-Emmett-Taylor (BET) method, and pore size distribution was estimated using nonlocal density functional theory (NLDFT).

[0072] Inductively Coupled Plasma Emission Spectrometry (ICP-OES): The concentration of metal ions in purified water was determined using an Agilent 725 inductively coupled plasma emission spectrometer.

[0073] Optical contact angle: The water contact angle of the conjugated microporous polymer material was tested using a Krüger DSA100 contact angle meter in Germany, using a 5μL water droplet.

[0074] Photothermal performance characterization: The 660nm laser was generated by an LDDVA660 laser, and the temperature response of the sample was measured by a FLIR-ONEEDGEPRO infrared thermal imager.

[0075] Photoelectrochemical testing: All photoelectrochemical tests were performed on a Shanghai Chenhua CHI760E electrochemical workstation using a standard three-electrode system at room temperature. The working electrode was a glassy carbon electrode (GCE) or an indium tin oxide (ITO) electrode, the counter electrode was a platinum wire electrode, and the reference electrode was a saturated calomel electrode (SCE).

[0076] Mott-Schottky analysis: The working electrode was a glassy carbon electrode covered with a polymer film and 5 wt% perfluorosulfonic acid resin (Nafion), the electrolyte was a 0.1 mol·L⁻¹ sodium sulfate (Na₂SO₄) aqueous solution, the test frequencies were 1000 Hz, 1500 Hz and 2000 Hz, and the amplitude was 5 mV.

[0077] Electrochemical impedance spectroscopy (EIS) test: Using potassium ferricyanide / potassium ferrocyanide ([Fe(CN)6]6) at a concentration of 5 mmol·L⁻¹ 3- / 4- 0.1 mol·L -1The procedure was performed at room temperature in potassium chloride (KCl) solution. A slurry was prepared by mixing 5 mg of DP-CMP1 sample, 225 μL of deionized water, 225 μL of ethanol (EtOH), and 50 μL of N-methylpyrrolidone (NMP) solution containing 1.5 wt% polyvinylidene fluoride (PVDF). 7 μL of this slurry was coated onto a glassy carbon electrode as the working electrode. The applied potential relative to a saturated calomel electrode was converted to a potential relative to a standard hydrogen electrode (NHE) or a reversible hydrogen electrode (RHE) using the following formula:

[0078] E NHE =E SCE +E θ SCE (E θ SCE = 0.242 V) (1)

[0079] E RHE =E SCE +0.0591pH+E θ SCE (E θ SCE = 0.242 V) (2)

[0080] Photocurrent testing: An ITO electrode (1.0 × 1.5 cm²) coated with DP-CMP was used as the photoelectrode. Visible light was generated by a 300W xenon lamp (Zhongjiao Jinyuan CEL-HXF300) equipped with an AM1.5G cutoff filter, manually chopping the light. 5 mg of DP-CMP1 was added to 1 mL of ethanol and 10 μL of 5 wt% perfluorosulfonic acid resin (Nafion), and sonicated for 30 min to prepare a slurry. 50 μL of this slurry was coated onto ITO glass and air-dried. The electrolyte was a 0.1 mol·L⁻¹ sodium sulfate (Na₂SO₄) aqueous solution (pH=6.8), bubbled with high-purity nitrogen gas for 30 min at room temperature. Photocurrent testing was conducted at -0.64 V (relative to SCE), with an intermittent irradiation period of 50 s and a total testing time of 800 s. The photocurrent density was determined based on the actual light-receiving area of ​​the photoelectrode (1.0 cm²). 2 Calculate using the following formula:

[0081] Photocurrent density (J) photocurrent density = Measured photocurrent (J) measured photocurrent ) / Actual light-receiving area (S) actual radiation area (3)

[0082] Experimental steps:

[0083] Material:

[0084] 2,6-Dimethyl-4H-pyran-4-one and benzoic anhydride were purchased from Tianjin Xins Biochemical Technology Co., Ltd.; terephthalaldehyde was purchased from Anhui Zesheng Technology Co., Ltd.; glutaraldehyde (50%), benzaldehyde, and benzoic acid were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; polyvinyl alcohol (PVA) with a number average molecular weight of 15,000 and other chemicals were purchased from Sigma-Aldrich. The seawater used for the desalination test was taken from the deep sea off Qingdao and did not require further sterilization. Copper nitrate, zinc chloride, nickel chloride, and silver nitrate were dissolved in deionized water to prepare a Cu-containing desalination solution. 2+ Zn 2+ Ni 2+ Simulated wastewater containing heavy metal ions such as Ag+.

[0085] Synthesis of 2,2',6,6'-tetramethyl-4,4'-bipyranide (TMDP):

[0086]

[0087] 2,6-Dimethyl-4H-pyran-4-one (229.6 mg, 1.85 mmol) and Lawson's reagent (374.5 mg, 0.926 mmol) were added to a dry, short-necked ampoule. The gas atmosphere inside the ampoule was purged by a vacuum-nitrogen cycle, and then 30 mL of oxygen-free toluene was added through the short neck using a syringe. The reaction system was heated to 120 °C and refluxed with stirring for 48 h. After the reaction was completed, heating was stopped, and the mixture was cooled to room temperature. The reaction mixture was filtered, and the filter cake was thoroughly washed with dichloromethane (DCM). The filtrates were combined and concentrated using a rotary evaporator. The resulting crude solid product was purified by silica gel column chromatography (eluent: dichloromethane). After drying, the target product TMDP (162 mg, 93.1% yield) was obtained as a yellow solid. 1 H NMR (400 MHz, CDCl3): δ=6.95 (s, 1H), 2.22 (s, 3H); 13 C NMR (100 MHz, CDCl3): δ=201.98, 158.99, 124.63, 19.30 ppm.

[0088] Synthesis of model compounds (MC):

[0089]

[0090] Add 2,2',6,6'-tetramethyl-4,4'-bipyranide (43.26 mg, 0.2 mmol), benzaldehyde (0.2 mL, 2 mmol), benzoic anhydride (45.2 mg, 0.2 mmol), and benzoic acid (2.5 mg, 0.02 mmol) to a 2 mL Pyrex tube. Rapidly freeze the mixture at 77 K (liquid nitrogen bath), perform three vacuum degassing cycles, and then flame seal the Pyrex tube. Heat the sealed tube at 180 °C for 3 days. After cooling to room temperature, separate the residual crude solid product, purify by silica gel column chromatography (eluent: dichloromethane / petroleum ether = 3 / 1), and dry to obtain a dark brown solid target product (80 mg, 70% yield). 1 H NMR (400 MHz, CDCl3): δ=7.60-7.58 (m, 10H), 7.54 (s, 2H), 7.46-7.42 (m, 12H), 7.10 (s, 4H), 6.74 (s, 2H), 6.70 (s, 2H); 13 C NMR (100 MHz, CDCl3): δ=200.78, 154.13, 137.27, 135.01, 130.08, 129.11, 127.71, 124.74, 119.32 ppm.

[0091] Synthesis of the copolymer microporous polymer DP-CMP1:

[0092]

[0093] 2,2',6,6'-Tetramethyl-4,4'-bipyranide (21.63 mg, 0.1 mmol), terephthalaldehyde (26.9 mg, 0.2 mmol), benzoic anhydride (45.2 mg, 0.2 mmol), and benzoic acid (2.5 mg, 0.02 mmol) were added to a 2 mL Piezx tube. The mixture was rapidly frozen at 77 K (liquid nitrogen bath), and after three vacuum degassing cycles, the Piezx tube was flame-sealed. The sealed tube was heated at 180 °C for 3 days, cooled to room temperature, and the lumpy monomer was soaked in acetone solution for 24 h. After removing the liquid, the solid was crushed with a hammer and ground into powder in a mortar. The powder was washed successively with acetone and tetrahydrofuran, followed by Soxhlet extraction with tetrahydrofuran for 24 h, and vacuum dried at 80 °C for 12 h to obtain a black solid powder product with a yield of 92.3%.

[0094] Synthesis of polyvinyl alcohol (PVA) gel:

[0095] Typical synthesis procedure: 1 g polyvinyl alcohol (PVA), 125 μL glutaraldehyde, and 10 mL deionized water are ultrasonically mixed, followed by reflux heating at 100 °C for 2 h (denoted as solution C). 50 μL of 1.2 mol·L⁻¹ phosphate dehydrogenase is added to 10 mL of solution C. -1 The polyvinyl alcohol (PVA) gel was subjected to a hydrochloric acid (HCl) solution for 2 hours. The resulting PVA gel was then immersed in deionized water overnight for purification, followed by freezing with liquid nitrogen, thawing in deionized water at 30°C, and repeating this freeze-thaw cycle 10 times. Finally, the PVA gel was freeze-dried to obtain the final PVA gel.

[0096] Synthesis of PVA+DP-CMP1 composite gel:

[0097] Typical synthesis procedure: 1 g polyvinyl alcohol (PVA), 125 μL glutaraldehyde, and 10 mL deionized water are ultrasonically mixed, followed by reflux heating at 100 °C for 2 h (denoted as solution C). 50 μL of 1.2 mol·L⁻¹ phosphate dehydrogenase is added to 10 mL of solution C. -1 The gelation reaction was carried out in hydrochloric acid (HCl) solution and 15 mg (1.5 wt%) of DP-CMP1 powder for 2 h. The resulting composite gel was immersed in deionized water overnight for purification, then frozen in liquid nitrogen, and then thawed in deionized water at 30 °C. This freeze-thaw cycle was repeated 10 times, and finally freeze-dried to obtain the PVA+DP-CMP1 (1.5 wt%) composite gel sample.

[0098] Water vapor generation experiment:

[0099] A material approximately 2 mm thick and 10 cm in area 2 A circular sample was placed on polystyrene (PS) foam in a 50 mL beaker. The PS foam was used to isolate the sample from the water, preventing direct heat dissipation from the sample to the water. A paper towel was sandwiched between the sample and the foam to connect the sample to the water reservoir for moisture transfer. Under stable solar irradiation, the sample was irradiated using a solar simulator, and the surface temperature changes were recorded using a Fi400 infrared thermal imager. The evaporation rate was measured under steady-state conditions, and the mass loss of the entire apparatus was recorded using an electronic balance.

[0100] DP-CMP1 / PVA ratio optimization:

[0101] For the PVA+DP-CMP1 composite gel, the optimal mass ratio of DP-CMP1 to PVA is 0.015:1. This optimized ratio accelerates solar vapor generation and reduces the cost of using DP-CMP1. Control samples with DP-CMP1 / PVA mass ratios of 0.01:1, 0.015:1, and 0.02:1 were set up, corresponding to PVA+DP-CMP1 (1 wt%), PVA+DP-CMP1 (1.5 wt%), and PVA+DP-CMP1 (2 wt%), respectively, and their solar vapor generation performance was tested under one solar irradiance. The results showed that the solar evaporation rates for the three samples were approximately 3.38, 3.83, and 3.52 kg·m³, respectively. -2 ·h -1 Therefore, the optimal mass ratio of DP-CMP1 to PVA in PVA+DP-CMP1 is recommended to be 0.015:1.

[0102] Experimental methods for purifying seawater and water contaminated with heavy metal ions:

[0103] Seawater desalination performance testing: Purified water was collected using a self-made transparent glass apparatus under solar simulator irradiation. The main metal ions (Na+, Sodium, Na+, Sodium) in the seawater and purified water were determined using an Agilent 725 inductively coupled plasma optical emission spectrometer (ICP-OES). + K + Mg 2+ Ca 2+ )concentration.

[0104] Heavy metal ion contaminated water purification test: Cu was added to deionized water 2+ Zn 2+ Ni 2+ Ag + Simulated wastewater was prepared using four metal ions. After collecting the condensate through solar steam generation, the concentration of metal ions in the purified water was determined using inductively coupled plasma optical emission spectrometry (ICP-OES).

[0105] Outdoor water purification experiment:

[0106] An outdoor seawater desalination experiment was conducted using a self-made transparent glass apparatus. Two 3.5 cm diameter PVA+DP-CMP1 (1.5 wt%) hydrogel sheets were placed on the evaporation unit, and the apparatus was placed outdoors under natural sunlight. From 9:00 to 18:00 on June 26, 2025, the system mass change and temperature were measured hourly, and the corresponding solar irradiance and outdoor temperature were recorded.

[0107] Energy consumption estimation for dark-state experiments:

[0108] Based on the literature method, an experiment was designed to estimate the enthalpy of evaporation of the hydrogel: Pure water and hydrogel samples with the same surface area were simultaneously placed in a sealed container containing a supersaturated potassium carbonate solution, and the relative humidity inside the container was stabilized at approximately 45% (room temperature, normal pressure). The mass changes of both samples were recorded under dark conditions, and the enthalpy of evaporation of water in the hydrogel was estimated using the following formula:

[0109] U in = E equ m h =E 0 m 0

[0110] Where E0 is the enthalpy of vaporization of pure water, and m0 (0.163 kg·m -2 ·h -1 The mass change of pure water (in an anhydrous electrogel evaporator) under dark conditions is m. h This represents the mass change of the hydrogel under the same conditions. Based on a constant input power (U... in ), by comparing with the known theoretical enthalpy of vaporization of liquid water (2450 J·g), -1 By comparison, the equivalent enthalpy of evaporation (E) is calculated. equ ).

[0111] Energy conversion efficiency:

[0112] Solar energy conversion efficiency (η) is calculated using the following formula:

[0113] η = mE equ / P0

[0114] Where m is the net evaporation rate (evaporation rate under one solar irradiation minus the dark evaporation rate), and E equ P0 is the equivalent enthalpy of vaporization of water in the PVA+DP-CMP1 composite gel, and P0 is the irradiance of one solar power (1 kW·m). -2 For PVA+DP-CMP1 (1.5 wt%), m = 3.83 - 0.39 = 3.44 kg·m -2 ·h -1 E_equ=1020.8 J·g -1 Therefore, under one solar irradiation, the solar energy conversion efficiency of PVA+DP-CMP1 (1.5 wt%) is 97.54%.

[0115] Results and Discussion:

[0116] 4,4'-Bipyranyl (DP) contains two pyranyl heterocyclic rings connected by an exocyclic carbon-carbon double bond at the oxygen atom para position. Its structure exhibits a highly extended π-conjugated system, possessing strong absorption, strong intermolecular interactions, and excellent redox activity. Therefore, DP derivatives are widely used as carrier transport materials in solar cells and organic field-effect transistors. However, porous organic polymers (POPs) containing DP structural units have not yet been prepared and developed. This application presents the first synthesis of a fully conjugated DP-based conjugated microporous polymer with a high specific surface area. The polymer was successfully constructed via an aldol condensation reaction using 2,2',6,6'-tetramethyl-4,4'-bipyranyl (TMDP) and an aromatic dialdehyde as comonomers. This design strategy offers the following key advantages: 1) The DP unit possesses excellent light-harvesting capability and strong π-π interactions, effectively promoting photon capture in the polymer; 2) The introduction of vinylidene linkages not only significantly broadens the polymer's light absorption range but also enhances skeletal stability; 3) Metal-free catalyst synthesis reduces the production cost of the target polymer; 4) The inherent ultraporous structure and heteroatoms on the pore walls are expected to improve the wettability and moisture transport capacity of DP-CMP1, thereby promoting efficient moisture evaporation. Benefiting from these advantages, a well-designed DP-CMP1 not only exhibits inherent porosity, good wettability, and low thermal conductivity but also demonstrates broad-spectrum light harvesting, high solar-to-thermal energy conversion efficiency, and excellent stability. It is worth noting that, as... Figure 9 As shown, under 660 nm laser irradiation, the temperature of DP-CMP1 can rapidly rise from 29.1℃ to 174.7℃ in just 4 seconds. Furthermore, in an interfacial heating evaporation system, DP-CMP1 achieves a solar thermal-driven water evaporation rate of 3.83 kg·m³ for pure water under one solar irradiation. -2 ·h -1 It boasts an energy conversion efficiency of up to 97.5% and exhibits long-term stability. Theoretical studies have shown that DP-CMP1 possesses a small band gap, a faster nonradiative recombination rate, a larger non-adiabatic coupling value, and stronger electron-phonon coupling, thus making it an excellent solar-to-thermal energy conversion material.

[0117] To synthesize DP-based porous polymers, TMDP was first designed and synthesized using an improved method. Subsequently, the synthesis of the model compound (MC) was explored: TMDP and benzaldehyde underwent anal condensation at 180°C for 72 h in the presence of benzoic anhydride and benzoic acid to yield a dark brown vinylidene-linked compound with a separation yield of 70%. Replacing benzaldehyde with terephthalaldehyde (TPA) under the same reaction conditions, a fully conjugated DP-based porous polymer could still be synthesized. After reacting at 180°C for 72 h, the precipitate was washed with acetone and tetrahydrofuran (THF) and dried under vacuum at 80°C for 24 h to obtain the target product DP-CMP1, a black powder with a high yield of 92.3%. The target product is insoluble in water and typical organic solvents such as tetrahydrofuran, toluene, acetone, chloroform, and methanol.

[0118] The framework structure of DP-CMP1 was determined for the first time using Fourier transform infrared (FT-IR) spectroscopy. Compared to the monomer, the stretching vibration signal at 1693 cm⁻¹ corresponding to the aldehyde group almost completely disappeared in the FT-IR spectrum of DP-CMP1, and the signal at approximately 1590 cm⁻¹ was also significantly reduced. -1 and 1007 cm -1 A new peak appears, attributed to the stretching vibration band of the carbon-carbon double bond, indicating the formation of vinylidene linkages and the high degree of condensation in the polymerization reaction. Simultaneously, through solid-state... 13 C-cross polarized magic angle rotating nuclear magnetic resonance (C-C) 13 CCP-MAS NMR spectroscopy characterized DP-CMP1 at the molecular level, detecting characteristic carbon signals of the carbon-carbon double bond (C=C) in DP-CMP1 at 117 ppm and 134 ppm, respectively. Similarly, Fourier transform infrared spectroscopy and... 13 The characteristic signal of carbon-carbon double bonds (C=C) also appeared in the C NMR spectrum. Figure 1 ).

[0119] The intrinsic porosity of the novel fully conjugated DP-based CMP1 was evaluated using a nitrogen adsorption-desorption isotherm at 77 K. All DP-CMP1 cells exhibited a Type I adsorption-desorption isotherm, indicating their microporous characteristics. Based on nitrogen adsorption data, the Brunol-Emmett-Taylor (BET) specific surface area of ​​DP-CMP1 was calculated to be 841 m². 2 ·g -1 The total pore volume is 0.39 cm³ when P / P0 = 0.99. 3 ·g -1 Analysis using the Saito-Foley method revealed that the pore size distribution of DP-CMP1 is multi-level, ranging from 0.5 to 2.1 nm. Figure 2Furthermore, no obvious signal peaks were observed in the powder X-ray diffraction (PXRD) curves of DP-CMP1, indicating the amorphous properties of the novel polymer. Figure 3 Field emission scanning electron microscopy (FE-SEM) images show that the pure solid phase consists of micron-sized spherical particles. Figure 4 ).

[0120] The thermal stability of DP-CMP1 was evaluated by thermogravimetric analysis (TGA) under a nitrogen atmosphere. The obtained spectra showed that the polymer had good thermal stability below 400℃. Figure 5 Furthermore, by immersing polymer samples in N,N-dimethylformamide (DMF), tetrahydrofuran (THF), water, 6 mol·L⁻¹ -1 Sodium hydroxide (NaOH) and 6 mol·L -1 The chemical durability of the sample was investigated by placing it in an aqueous hydrochloric acid (HCl) solution at room temperature for 3 days. Reassuringly, the collected sample after filtration still maintained the original skeleton connectivity. Figure 6 This indicates its excellent chemical stability. Furthermore, contact angle experiments show that DP-CMP1 exhibits good hydrophilicity, demonstrating rapid water penetration (…). Figure 7 ).

[0121] Next, the light-harvesting ability of fully conjugated DP-CMP1 was explored using ultraviolet-visible-near-infrared (UV / Vis-NIR) spectroscopy. Compared with the model compound, DP-CMP1 exhibited a broad absorption band in the solid state, covering the 300-2000 nm range, consistent with its black appearance, which effectively promoted sunlight capture. To evaluate the solar-to-thermal energy conversion performance of DP-CMP1, its surface temperature was monitored in real time using an infrared thermal imager. Figure 9 As shown, 20 mg of DP-CMP1 powder at 100 mW·cm -2 Under 660nm laser irradiation, the surface temperature rapidly rose to approximately 174.7℃ within 4 seconds, and reached 180.2℃ when the irradiation time was extended to 60 seconds; after the laser was removed, the temperature almost returned to its initial state within 10 seconds, indicating a rapid photothermal conversion process. Under the same conditions, the surface temperature of the model compound (MC) was only 96.9℃. Figure 8 The concentrations of DP-based conjugated microporous polymers were significantly lower than those of DP-CMP1, demonstrating the substantial advantages of DP-based conjugated microporous polymers in photothermal conversion. Furthermore, using 20 mg of sample, the concentrations were significantly lower in the range of 25–125 mW·cm⁻¹. -2 The effect of optical power density on photothermal conversion was evaluated within the range. Figure 9 (b) Obviously, the higher the laser power, the faster the heating rate and the higher the equilibrium temperature. This is especially true when the DP-CMP1 is at 125 mW·cm⁻¹. -2Under 660 nm laser irradiation, the equilibrium temperature can reach 213℃ ( Figure 9 b), surpassing previously reported state-of-the-art materials, including organic molecules, linear polymers, crystalline covalent organic frameworks, and metal-organic frameworks. Subsequently, the photothermal cycling stability was investigated through six laser irradiation-shutdown cycles. Figure 9 c), the results showed that the equilibrium temperature remained constant during the experiment, indicating that DP-CMP1 has excellent resistance to photobleaching. Importantly, the cycled samples still retained their original linkage structure, morphology, and broad absorption bands. Figure 10 ). Figure 10 In the figure, a) is the FT-IR spectrum, showing no significant shift in characteristic peak shape and wavenumber before and after cycling, and stable signals of key functional groups such as carbon-carbon double bonds, indicating that the original framework remains connected after six cycles and the chemical structure has not been damaged by repeated thermal shock; b) is the SEM image, showing complete micron-sized spherical particle morphology before and after cycling, without agglomeration, breakage, or structural collapse, ensuring the integrity of the material's pore structure and providing a stable channel for water transport and light absorption; c) is the absorption spectrum, maintaining a broad absorption range of 300-2500 nm after cycling, with no significant decrease in absorbance, indicating excellent anti-photobleaching performance and no decrease in light-harvesting ability during long-term use. Furthermore, under xenon lamp simulated sunlight irradiation (100 mW·cm⁻¹), [the following data is also presented]. -2 Even at AM 1.5G, the DP-CMP1 still exhibited high-efficiency solar-to-thermal energy conversion performance, with the highest temperature of the DP-CMP1 reaching 141.2℃ after 8 minutes.

[0122] Tauc diagram ( Figure 21 The data shows that the DP-CMP1 has a bandgap of only 1.30 eV. This narrow bandgap structure enables it to efficiently capture photons in the visible and near-infrared regions, providing a basis for the large-scale generation of photogenerated carriers. (Transient current density plot) Figure 22 In the electrochemical impedance spectroscopy (EIS), the material exhibits a fast response and stable amplitude current curve under intermittent illumination, indicating high separation efficiency and low recombination rate of photogenerated electron-hole pairs, as well as excellent carrier mobility. Figure 23 The smaller semicircular diameter further reveals its charge transport advantages; the smaller semicircular diameter corresponds to a lower charge transfer resistance, effectively reducing energy loss during carrier transport and ensuring charge utilization efficiency. These three factors synergistically demonstrate that DP-CMP1 performs exceptionally well in light absorption, carrier separation, and charge transport, providing solid support for its efficient applications in photothermal conversion, photoelectrocatalysis, and other fields.

[0123] DP-CMP1 possesses broad-spectrum light harvesting, excellent solar-to-thermal energy conversion capabilities, abundant porosity, and outstanding durability, which inspires us to explore its potential applications in solar steam generation. Therefore, using polyvinyl alcohol (PVA), which has good hydrophilicity and low thermal conductivity, as a supporting framework, a series of DP-CMP-supported gel networks were constructed through an in-situ co-gelation process. Figure 11 Compared to pure polyvinyl alcohol (PVA), digital photographs show that PVA+DP-CMP1 (1.5 wt%) is pure black, while scanning electron microscopy (SEM) images show that its morphology is similar to that of pure polyvinyl alcohol (PVA). Figure 11 This indicates that DP-CMP1 was effectively loaded into the composite hydrogel. It is well known that the macroporous structure of composite hydrogels effectively promotes water transport, and the localized heat generated by the DP-CMP material greatly accelerates water evaporation. Encouragingly, PVA+DP-CMP1 (1.5 wt%) also exhibits excellent light absorption, covering almost the entire solar absorption spectrum. Simultaneously, the thermal conductivity of DP-CMP1 at 25℃ was measured to be 0.087 W·m. -1 ·K -1 This indicates its low thermal conductivity, which is beneficial for heat insulation. Furthermore, by recording simulated sunlight exposure (100 mW•cm²), [further details are needed]. -2 The solar-to-thermal energy conversion performance of PVA+DP-CMP1s was evaluated by measuring the temperature change of AM 1.5G. The results showed that the surface temperature of PVA+DP-CMP1 (1.5 wt%) rapidly reached equilibrium at 64.8℃ within 300 seconds, while the surface temperature of pure polyvinyl alcohol (PVA) was only 30.6℃ under the same experimental conditions.

[0124] Subsequently, in the simulation device ( Figure 12 The study recorded the effects of polyvinyl alcohol (PVA) and PVA+DP-CMP1 (1.5 wt%) under light irradiation (100 mW•cm). -2 Typical moisture mass change curves for PVA+DP-CMP1 (1.5 wt%) were used to evaluate the efficiency of solar-driven moisture evaporation. Based on the slope of the moisture mass change curve over time, the evaporation rate of PVA+DP-CMP1 (1.5 wt%) was calculated to be as high as 3.83 kg•m³. -2 •h -1 The concentration was significantly higher than that of pure water (0.47 kg•m³). -2 •h -1 Under the same conditions, the water evaporation rate of pure polyvinyl alcohol (PVA) is only 0.93 kg•m. -2 •h -1This clearly demonstrates the unique role of DP-CMP in the composite hydrogel. Surprisingly, this evaporation rate is superior to that of previously reported molecular-based materials (PU+CR-TPE-T: 1.272 kg•m). -2 •h -1 GDPA-QCN cellulose paper: 1.30 kg•m -2 •h -1 ), organic porous polymer (PU+GS-POP-2: 1.402 kg•m -2 •h -1 ) and covalent organic framework (TBBPE: 2.82 kg•m -2 •h -1 TPAD-COF: 1.42 kg•m -2 •h -1 CGH-50: 3.69 kg•m -2 •h -1 Calculations showed that the solar-driven water evaporation efficiency of PVA+DP-CMP1 (1.5 wt%) was 97.5%. The novel evaporation system maintained a high evaporation rate even in strongly acidic and alkaline aqueous solutions. Furthermore, the study found that the water evaporation rate increased with increasing solar irradiance, reaching a higher rate at an optical density of 200 mW•cm². -2 At 2 suns, the water evaporation rate of PVA+DP-CMP1 (1.5 wt%) can be increased to 5.81 kg•m. -2 •h -1 ( Figure 14 It is worth noting that the composite hydrogel PVA+DP-CMP1 (1.5 wt%) maintained excellent and stable solar-driven water evaporation capacity after ten cycles. Figure 15 Furthermore, the water evaporation rate of polyvinyl alcohol (PVA) composite gels with different DP-CMP loadings was evaluated. The results showed that increasing or decreasing the DP-CMP loading in polyvinyl alcohol (PVA) led to a decrease in the water evaporation rate. Figure 16 This is attributed to the need to balance light absorption and resistance to moisture transport in order to achieve maximum moisture evaporation.

[0125] Next, the practicality of PVA+DP-CMP1 (1.5 wt%) in seawater desalination was further evaluated. When seawater (taken from the Yellow Sea, China) was used as the water source, at 100 mW•cm -2 Under solar irradiation, the water evaporation rate of PVA+DP-CMP1 (1.5 wt%) was 3.77 kg•m. -2 •h -1 ( Figure 17Similar to pure water, PVA+DP-CMP1 also exhibited excellent long-term durability in actual seawater evaporation. After ten cycles of one-hour operation, its desalination performance remained stable. Figure 18 It is noteworthy that no salt accumulation occurred during the ten cycles of the experiment. Figure 19 Furthermore, the water evaporation rate of PVA+DP-CMP1 did not change significantly in salt solutions of different concentrations. Figure 20 ).

[0126] Four major ions (Na+, Na+, and Sodium) were measured before and after seawater desalination using inductively coupled plasma optical emission spectrometry (ICP-OES). + K + Mg 2+ Ca 2+ The concentration of ), such as Figure 24 As shown, the concentration of these ions in the desalinated water decreased significantly by approximately four orders of magnitude, fully meeting the drinking water standards set by the World Health Organization (WHO). Simultaneously, PVA+DP-CMP1 (1.5 wt%) can also be used to purify wastewater containing heavy metal ions; after purification, Cu... 2+ Ni 2+ Zn 2+ Ag + The concentrations of heavy metal ions decreased significantly. Figure 25 Furthermore, an outdoor evaporation test was conducted under sunny environmental conditions (June 26, 2025, Changchun, China, 9:00-18:00). At a solar irradiance of 730 W•m⁻² (13:00), the highest evaporation rate reached 3.10 kg•m⁻². -2 •h -1 The daily water production is 21.1 kg•m -2 This indicates that the novel water evaporation system has great potential in practical applications.

[0127] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and embodiments shown and described herein.

Claims

1. A conjugated microporous polymer based on terephthalaldehyde, characterized in that, The structural formula of the conjugated microporous polymer based on terephthalaldehyde is as follows: 。 2. The method for preparing the conjugated microporous polymer based on terephthalaldehyde as described in claim 1, characterized in that, include: 2,2',6,6'-tetramethyl-4,4'-bipyranide, terephthalaldehyde, benzoic anhydride and benzoic acid are mixed in a container, flash-frozen in a liquid nitrogen bath, degassed under vacuum and then sealed in the container. The mixture is then reacted at 170-190°C for 2-4 days. After the reaction was completed, the blocky monomer was soaked in acetone for 20-30 hours, crushed into powder, washed with acetone and tetrahydrofuran in sequence, and extracted with tetrahydrofuran by Soxhlet extraction for 20-30 hours. Finally, it was vacuum dried at 75-85℃ for 10-14 hours to obtain a conjugated microporous polymer based on terephthalaldehyde.

3. The preparation method according to claim 2, characterized in that, The molar ratio of 2,2',6,6'-tetramethyl-4,4'-bipyranide, terephthalaldehyde, benzoic anhydride and benzoic acid is 1:(1.8-2.2):(1.8-2.2):(0.18-0.22).

4. A gel composite material, characterized in that, It comprises the terephthalaldehyde-based conjugated microporous polymer as described in claim 1 and polyvinyl alcohol.

5. The gel composite material as described in claim 4, characterized in that, The mass ratio of the conjugated microporous polymer based on terephthalaldehyde to polyvinyl alcohol is (0.01-0.02):

1.

6. The application of the conjugated microporous polymer based on terephthalaldehyde as described in claim 1 in the preparation of photothermal conversion materials.

7. The application of the conjugated microporous polymer based on terephthalaldehyde as described in claim 1 or the gel composite material as described in claim 4 in seawater desalination.

8. The application of the conjugated microporous polymer based on terephthalaldehyde as described in claim 1 or the gel composite material as described in claim 4 in wastewater purification.

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