Preparation method and application of water and organic solvent stable two-dimensional polymer fullerene film

Abstract

The application belongs to the technical field of high polymer materials, and particularly relates to a preparation method and application of a two-dimensional polymer fullerene membrane stable to water and organic solvents. The preparation method comprises the following steps: uniformly mixing N-methyl pyrrolidone (NMP) solvent and a two-dimensional polymer fullerene dispersion solution to obtain a C60 diluent; placing a substrate filter membrane containing a supporting membrane at the bottom of a filter head of a suction filter bottle, wetting the substrate filter membrane with an appropriate amount of NMP solvent, starting a suction filter pump, closing the pump after 1-3 minutes of suction filtration, and then fixing the filter cup at the upper end of the filter head; and starting the suction filter pump again and pouring the C60 diluent into the filter cup. The two-dimensional polymer fullerene dispersion solution is mixed with NMP and subjected to suction filtration, and a two-dimensional polymer fullerene membrane is prepared through annealing treatment. The two-dimensional polymer fullerene membrane allows water molecules to pass through while retaining ions, enhances interlayer bonding, improves the anti-swelling property and stability of the membrane, and realizes efficient liquid phase separation.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of high polymer materials, and particularly relates to a preparation method and application of a two-dimensional polymer fullerene membrane stable in water and organic solvents. BACKGROUND

[0002] In recent years, two-dimensional materials such as graphene, transition metal sulfides and MXene have shown great potential in the field of membrane separation due to their atomic thickness, high mechanical strength and adjustable interlayer channel characteristics. The nanochannels of these materials can achieve high-efficiency selective separation of small molecules, ions and even water through chemical modification or physical stacking. In 2022, two-dimensional polymer fullerene was first synthesized by a research team of Professor Zheng Jian of the Chinese Academy of Sciences, as a new all-carbon two-dimensional semiconductor, it is a new allotrope of carbon material family, which is formed by specific covalent bonding of C60 molecules in the plane, with a thickness of only one fullerene molecule and a band gap of about 1.6 eV. In particular, the quasi-hexagonal two-dimensional fullerene has a native angstrom pore structure, with an equivalent pore size between water molecules and hydrated inorganic salt ions, making it an ideal water / salt separation material.

[0003] However, the research on two-dimensional polymer fullerene is still in its infancy, and the existing technology has significant defects. In the existing technology, the prepared two-dimensional fullerene multilayer membrane can only allow gaseous organic molecules to pass through, and has insufficient stability in liquid solvents, which will disperse within 10 seconds, and cannot be used for liquid separation. Other related two-dimensional membranes such as graphene oxide membranes and COF membranes have attempted to improve stability, but have problems such as structural collapse caused by residual cross-linking agent, poor intercalation stability, and dependence on high-toxicity cross-linking agents to block channels, which cannot achieve dual stability in water and organic phases, and seriously limit their application in the field of liquid membrane separation.

[0004] Therefore, it is urgent to develop a mild and pollution-free preparation method of two-dimensional polymer fullerene membrane to solve the problem of rapid delamination and dispersion in water and organic phases, achieve high permeability and high selectivity while maintaining the integrity of the intrinsic nanochannel, and promote its practical application in the fields of seawater desalination and organic solvent nanofiltration. SUMMARY

[0005] The purpose of the present application is to provide a preparation method and application of a two-dimensional polymer fullerene membrane stable in water and organic solvents. The two-dimensional polymer fullerene dispersion liquid is mixed with NMP and subjected to suction filtration, forming a two-dimensional polymer fullerene membrane wet material with AA-type ordered layered structure on the PTFE filter membrane. After annealing treatment, the AA-type ordered layered structure is stabilized, thereby preparing a two-dimensional polymer fullerene membrane. The two-dimensional polymer fullerene membrane has a pore size of about 4.8 angstroms, allowing water molecules to pass through while retaining ions, and enhancing the interlayer bonding, improving the anti-swelling property and stability of the membrane, and achieving high-efficiency liquid phase separation.

[0006] The technical scheme adopted by the present application is as follows:

[0007] A preparation method of a water and organic solvent stable two-dimensional polymer fullerene film, comprising the following steps:

[0008] St1: uniformly mixing N-methyl pyrrolidone (NMP) solvent and two-dimensional polymer fullerene dispersion liquid to obtain C60 diluent;

[0009] St2: placing a substrate filter membrane containing a supporting film at the bottom on the filter head of a suction filter bottle, taking an appropriate amount of N-methyl pyrrolidone solvent to completely wet the substrate filter membrane, starting a suction filter pump to discharge the N-methyl pyrrolidone solvent in the suction filter bottle, and then closing the suction filter pump after 1-3 min, and fixing the filter cup on the upper end of the filter head;

[0010] St3: starting the suction filter pump again, slowly pouring the C60 diluent along the wall of the filter cup into the filter cup, and obtaining a substrate filter membrane containing two-dimensional polymer fullerene film wet material after the C60 diluent in the filter cup completely passes through the substrate filter membrane, wherein the two-dimensional polymer fullerene film wet material is an AA type ordered layered structure, and the substrate filter membrane is taken out and placed in a culture dish;

[0011] St4: preheating the air blowing drying equipment to 150-180℃, placing the substrate filter membrane into the drying box for annealing treatment and drying at 150-180℃, stabilizing the AA type ordered layered structure through the annealing treatment, taking out after 0.5-2h of drying, obtaining a substrate filter membrane covered with two-dimensional polymer fullerene film, and peeling off the supporting film at the bottom of the substrate filter membrane to obtain a two-dimensional polymer fullerene film containing the substrate filter membrane.

[0012] In a preferred scheme, in the St1, the volume ratio of the two-dimensional polymer fullerene dispersion liquid to the N-methyl pyrrolidone solvent is 1:99.

[0013] In a preferred scheme, the substrate filter membrane is a hydrophilic polytetrafluoroethylene (PTFE) filter membrane.

[0014] In a preferred scheme, the pore size of the hydrophilic polytetrafluoroethylene filter membrane is 0.1-0.3μm, and preferably, the pore size of the hydrophilic polytetrafluoroethylene filter membrane is 0.22μm.

[0015] In a preferred scheme, the concentration of the two-dimensional polymer fullerene dispersion liquid is 10mg / ml.

[0016] In a preferred scheme, in the St5, the air blowing rate inside the air blowing drying equipment is 10-15m 3 / h.

[0017] A two-dimensional polymer fullerene membrane prepared by the method for preparing a two-dimensional polymer fullerene membrane stable in water and organic solvents according to any one of the above, wherein the two-dimensional polymer fullerene membrane has a native Eikon structure, an equivalent pore size of about 4.8 Å, and is stable in both water and organic solvents.

[0018] In a preferred embodiment, the two-dimensional polymer fullerene membrane according to the application is used for separating organic small molecules, inorganic salt ions or water molecules in liquid phase membrane separation.

[0019] In a preferred embodiment, the organic small molecules include methylene blue, rhodamine B, methyl orange, methylene blue, and methyl red.

[0020] In a preferred embodiment, the inorganic salt ions include hydrated ions in copper chloride and sodium chloride.

[0021] The technical effects achieved by the application are as follows.

[0022] The two-dimensional polymer fullerene dispersion liquid is mixed with NMP, and then filtered by suction, and a two-dimensional polymer fullerene membrane is prepared after mild annealing treatment. The annealing treatment promotes the two-dimensional fullerene to form an AA type ordered layered structure through π-π stacking, and the native Eikon pore size is about 4.8 Å, which is between water molecules and hydrated inorganic salt ions. Efficient water molecule permeation and ion interception are achieved through size screening. At the same time, the heat treatment strengthens the interlayer covalent bond and van der Waals force, improves the anti-swelling ability of the membrane in solvents, and enhances the interlayer interaction to improve the stability of the membrane in solvents, so that efficient liquid phase separation can be achieved. The bottleneck of the traditional two-dimensional membrane in liquid phase is solved, and a high-efficiency and stable separation material is provided for seawater desalination and organic solvent nanofiltration. At the same time, no additional chemical pollution is introduced in the preparation process, the operation is simple, and it is easy to scale up, which provides convenience for the practical application of the two-dimensional polymer fullerene membrane. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a schematic diagram of the stability test results of the two-dimensional polymer fullerene membrane in water and organic solvents in Test Example One of the application;

[0024] Figure 2 is a schematic diagram of the contact angle change of the two-dimensional polymer fullerene membrane with time in Examples and Comparative Examples in Test Example Two of the application;

[0025] Figure 3 is a schematic diagram of the scanning electron microscope of the two-dimensional polymer fullerene membrane in Test Example Three of the application;

[0026] Figure 4 is a schematic diagram of the XRD characteristic peak of the two-dimensional polymer fullerene membrane in Test Example Three of the application;

[0027] Figure 5 This is a simulated XRD diagram of the two-dimensional polymer fullerene film in different stacking arrangements in Test Example 3 of the present invention;

[0028] Figure 6 This is a schematic diagram of the filtration test results of the two-dimensional polymer fullerene membrane in Test Example 4 of the present invention;

[0029] Figure 7 This is a schematic diagram of the methylene blue molecular filtration spectrum of the two-dimensional polymer fullerene membrane in Test Example 4 of the present invention;

[0030] Figure 8 This is a schematic diagram of the hydrated copper ion filtration spectrum of the two-dimensional polymer fullerene membrane in Test Example 4 of the present invention;

[0031] Figure 9 This is a schematic diagram of the methylene blue molecule and hydrated copper ion rejection rate of the two-dimensional polymer fullerene membrane in Test Example 4 of the present invention.

[0032] Figure 10 This is a schematic diagram of the proton blocking test of the two-dimensional polymer fullerene membrane in Test Example 5 of the present invention;

[0033] Figure 11 This is a schematic diagram of the hydroxide ion blocking test of the two-dimensional polymer fullerene membrane in Test Example 6 of the present invention.

[0034] Figure 12 This is a schematic diagram of the water permeability test results of the two-dimensional polymer fullerene membrane in Test Example 7 of the present invention;

[0035] Figure 13 This is a schematic diagram of the water flux test of the two-dimensional polymer fullerene membrane in Test Example 8 of the present invention;

[0036] Figure 14 This is a schematic diagram of the filtration performance test of the PTFE filter membrane in Test Example 9 of the present invention. Detailed Implementation

[0037] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0038] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0039] Second, the "one embodiment" or "an embodiment" referred to herein can include, and does not necessarily exclude, a specific feature, structure or characteristic that can be included in at least one implementation of the application. "In one preferred embodiment" appearing in various places in the specification are not all directed to the same embodiment, nor are they necessarily mutually exclusive of other embodiments.

[0040] Embodiment

[0041] Take 198 ml of N-methyl pyrrolidone (NMP) solvent and 2 ml of 10 mg / ml concentration of two-dimensional polymer fullerene dispersion liquid, stir on a magnetic stirrer at 300 rpm for 30 minutes to obtain a 100-fold diluted C60 diluent. A hydrophilic polytetrafluoroethylene (PTFE) filter membrane with a diameter of 50 mm, a pore size of 0.22 μm and a support film at the bottom is placed on the filter head of the suction filter bottle, 2 ml of NMP solvent is evenly dropped on the PTFE filter membrane to make it completely wet, the suction filter pump is opened for 1 minute and then closed, and the NMP solvent in the suction filter bottle is completely discharged. The filter cup is fixed above the filter head with a clamp, the suction filter pump is opened again, 35 ml of C60 diluent is slowly poured into the filter cup along the wall of the filter cup, and the suction process is observed until the C60 diluent in the filter cup completely passes through the PTFE filter membrane and no liquid drops. Continue to suction for 30 seconds to ensure that the C60 diluent on the PTFE filter membrane is completely suctioned. After the suction is completed, a PTFE filter membrane containing a two-dimensional polymer fullerene film wet material is obtained. The PTFE filter membrane is taken out and placed in a culture dish, the air drying oven is preheated to 160℃, the air blowing rate is set to 12 m 3 / h, and the PTFE filter membrane is placed in the drying oven for annealing treatment. After drying at 160℃ for 1 hour, it is naturally cooled to room temperature, the support film at the bottom of the PTFE filter membrane is peeled off, and a two-dimensional polymer fullerene film covered with a PTFE filter membrane at the bottom is obtained.

[0042] Further, the hydrophilic polytetrafluoroethylene (PTFE) obtained by purchase has a support film at the bottom and is not additionally added. The PTFE and the support film form an integral whole with a double-layer film structure in a way that the edges of them are connected to each other. After the preparation of the two-dimensional polymer fullerene film is completed, the support film will be peeled off, and the PTFE filter membrane at the bottom will not be peeled off. At the same time, only the support film is peeled off in the actual application process and in each test example below. The two-dimensional polymer fullerene film prepared in the above embodiment has a PTFE filter membrane at the bottom dried mainly for supporting, and the PTFE filter membrane itself does not have a liquid phase separation function (for the test of the PTFE filter membrane itself not having a liquid phase separation function, please refer to Test Example Nine).

[0043] It should be noted that in this embodiment, the specific components and preparation steps of the two-dimensional polymer fullerene dispersion liquid are described in the patent publication CN114956053A, Example 1 (paragraphs 91-93 of the specification). The components of the two-dimensional polymer fullerene dispersion liquid in this embodiment are identical to those of the polymer C60 dispersion liquid prepared in the above-mentioned reference Example 1. In this embodiment, the concentration of the two-dimensional polymer fullerene dispersion liquid is 10 mg / ml.

[0044] Here, in order to better describe the relevant performance of the product, the bottom of the two-dimensional polymer fullerene film in each test example below and the two-dimensional polymer fullerene film not specially described contains a PTFE filter film.

[0045] It should be noted that in this embodiment, the two-dimensional polymer fullerene film prepared is formed by physically stacking a single layer of fullerene network (i.e., a single layer of nanosheet) and is not obtained by chemical reaction.

[0046] Comparative Example

[0047] This comparative example is based on the example, and the annealing treatment is adjusted to air drying treatment. Specifically:

[0048] Take 198 ml of N-methyl pyrrolidone (NMP) solvent and 2 ml of two-dimensional polymer fullerene dispersion liquid with a concentration of 10 mg / ml, stir on a magnetic stirrer at 300 rpm for 30 minutes to obtain a 100-fold diluted C60 diluent. Place a hydrophilic polytetrafluoroethylene (PTFE) filter film with a diameter of 50 mm, a pore size of 0.22 μm, and a support film at the bottom of the filter head of the suction filter bottle. Drop 2 ml of NMP solvent evenly on the PTFE filter film to completely wet it. Open the suction filter pump and filter for 1 minute, then close it. Completely drain the NMP solvent in the suction filter bottle. Use a clamp to fix the filter cup above the filter head. Open the suction filter pump again, and slowly pour 35 ml of C60 diluent along the wall of the filter cup. Observe the filtration process until the C60 diluent in the filter cup completely passes through the PTFE filter film and no liquid drops. Continue to filter for 30 seconds to ensure that the C60 diluent on the PTFE filter film is completely filtered. After the filtration is completed, a PTFE filter film containing a two-dimensional polymer fullerene film wet material is obtained. Take out the PTFE filter film and place it in an air drying device. After air drying for 2 h, carefully peel off the support film at the bottom with tweezers to obtain a two-dimensional polymer fullerene film covered with a PTFE filter film at the bottom.

[0049] Test Example One

[0050] Water, NMP (N-methyl pyrrolidone), DMF (N,N-dimethylformamide), DMSO (dimethyl sulfoxide), ethanol, methanol, acetonitrile, acetone were respectively placed in different containers, and the two-dimensional polymer fullerene films prepared in the examples were immersed in the above containers. The dissolution state of the two-dimensional polymer fullerene films was observed every 24 hours and recorded. The dissolution state is shown in Table 1:

[0051] ;

[0052] Note: Table 1 is a record of the dissolution state of the two-dimensional polymer fullerene film in different solvents for 72 hours.

[0053] By comparing Table 1 and Figure 1 , it can be seen that the two-dimensional polymer fullerene films prepared in the examples do not show signs of dissolution or dispersion in water or organic solvents. The test results further confirm that the two-dimensional polymer fullerene films prepared in the examples are suitable for aqueous and organic phase solutions and exhibit excellent stability.

[0054] It should be noted that Figure 1 is a dissolution state diagram of the two-dimensional polymer fullerene film in different solvents for different dissolution times. The data in Table 1 only shows part of the test data.

[0055] Test Example Two

[0056] The two-dimensional polymer fullerene films prepared in the examples and comparative examples were respectively cut into 1 cm x 1 cm squares and fixed on the sample stage of a contact angle measuring instrument. The instrument was adjusted so that the lens was aligned with the center of the sample. The environmental temperature was set to 25°C and the humidity was set to 50%. 5 μL of ultrapure water was drawn into a microsyringe and slowly dropped onto the surface of the film at a rate of 0.5 μL / s. The measurement program was immediately started, and the initial contact angle of the droplet was recorded. The contact angle was continuously monitored for 20 seconds. Each sample was measured 3 times and the average value was taken. The contact angle differences of the films under different drying conditions were compared, and the results were recorded. The test results showed that the contact angle of the two-dimensional polymer fullerene film dried by air in the comparative example started from about 60° initially, and as time increased, the water penetrated down, the contact angle gradually decreased, and finally stabilized at about 0°. However, the contact angle of the two-dimensional polymer fullerene film annealed at 160°C in the example started from about 90° initially, and after a slight decrease, it stabilized at about 80° (see Figure 2 ).

[0057] In combination with Figure 2As can be seen from the comparative example, the two-dimensional polymer fullerene membrane treated by air drying has weak interlayer forces (relying solely on van der Waals forces), a loose structure, and polar sites (such as edge defects) that easily form hydrogen bonds with water, resulting in a sharp decrease in the contact angle. This indicates that its surface is highly hydrophilic, which is also the reason why traditional fullerene membranes dissolve rapidly in water. In contrast, the two-dimensional polymer fullerene membrane treated by annealing in the example promotes π-π stacking or covalent bond strengthening between the two-dimensional fullerene layers through thermal annealing, reduces the exposure of surface polar groups, and lowers the membrane's affinity for water molecules. Its surface exhibits strong hydrophobicity, but still allows water molecules to pass through (contact angle not reaching 180°). The hydrophobic surface prevents solvent molecules from damaging the membrane structure, while the native pores (4.8 Å) ensure efficient water molecule permeation, achieving the dual goals of "anti-swelling" and "high permeability".

[0058] Test Example 3

[0059] The two-dimensional polymer fullerene films prepared in the examples were analyzed using scanning electron microscopy, X-ray diffraction, and molecular simulation software. The results can be found in [link to relevant documentation]. Figures 3 to 5 As shown.

[0060] Figure 3 In the image, 'a' represents the SEM image at 100 μm, 'b' represents the SEM image at 50 μm, and 'c' represents the SEM image at 10 μm. (This is combined with...) Figure 3 , Figure 4 and Figure 5 It can be seen that the two-dimensional polymer fullerene membrane has good macroscopic continuity and uniformity. The multilayer physical stacked two-dimensional fullerene nanosheets have a sheet-like overlapping structure, with the layers closely arranged to form a regular layered network. The sheet thickness is uniform, and a regular pore structure (pore size of about 4.8 Å) is formed between the layers. This shows that the two-dimensional polymer fullerene membrane prepared in the example can efficiently retain ions while allowing water molecules to pass through, and has good separation performance.

[0061] Test Example 4

[0062] The two-dimensional polymer fullerene film prepared in the example is clamped in an H-shaped transparent test tank (pool body diameter 40 mm, height 50 mm; middle channel inner diameter 15 mm, outer diameter 30 mm), and a plurality of dye molecules and colored inorganic salts are selected as research objects, which are methylene blue (2.36 nm), rhodamine B (1.59 nm), methyl orange (1.54 nm), methyl blue (1.40 nm), methyl red (0.80 nm), and hydrated copper ions in CuCl2 solution (0.65 nm), etc. 50 mL of a 50 μg / ml dye aqueous solution is placed on the left side of the two-dimensional polymer fullerene film, and 50 mL of ultrapure water is placed on the right side. Whether the dye molecules can penetrate the film is observed and recorded, and the filtering ability of the film to small organic molecules is evaluated. Among them, the methyl red dye molecule is not easy to dissolve in water, 50 mL of a 50 μg / ml dye NMP solution is placed on the left side of the two-dimensional polymer fullerene film, and 50 mL of NMP solvent is placed on the right side. Whether the dye molecules can penetrate the film is observed and recorded, and the filtering ability of the film to small organic molecules is evaluated. Similarly, 50 mL of a 0.1M CuCl2 aqueous solution is placed on the left side of the two-dimensional polymer fullerene film, and 50 mL of ultrapure water is placed on the right side. Then, using a UV-visible spectrophotometer, the absorbance of the liquid in the right test tank is recorded in the wavelength range of 350-950 nm, and a spectrum is drawn. Similarly, when the methylene blue is used for the filtering performance test, because the content of the dye molecules in the methylene blue is high, in this test example, only the concentration of the methylene blue is 12.5 ug / mL.

[0063] Please refer to Figures 6 to 9 As shown in the above figures, within 5 days, the two-dimensional polymer fullerene film can effectively prevent the penetration of methylene blue molecules; within 12 days, the two-dimensional polymer fullerene film can effectively prevent the penetration of rhodamine B molecules; within 12 days, the two-dimensional polymer fullerene film can effectively prevent the penetration of methyl orange molecules; within 12 days, the two-dimensional polymer fullerene film can effectively prevent the penetration of methyl blue molecules; within 3 days, the two-dimensional polymer fullerene film can effectively prevent the penetration of methyl red molecules in NMP solvent; within 5 days, the two-dimensional polymer fullerene film can effectively prevent the penetration of hydrated copper ions. Through the above tests, the two-dimensional polymer fullerene film prepared in the example can efficiently intercept ions while allowing water molecules to penetrate, and has the ability to filter small molecule dyes and inorganic salt ions.

[0064] It should be noted that in the present test example, the way of obtaining the rejection rate is obtained by the automatic calculation of the ultraviolet / visible spectrophotometer, specifically, in the present test example, the ultraviolet / visible spectrophotometer is selected as UV-5500PC produced by Shanghai Precision Instruments Co., Ltd. Of course, the rejection rate can also be calculated manually by using the calculation formula, and the specific manual calculation method can refer to the calculation method disclosed in Hirunpinyopas W, Prestat E, Worrall SD, et al. Desalination and nanofiltration through functionalized laminar MoS2 membranes. ACS Nano, 2017, 11: 11082-11090, and in the present test example, the preferred way of obtaining the rejection rate is by automatic calculation of the equipment.

[0065] Further, in combination with Figure 9 It can be seen that the rejection rate of the two-dimensional polymer fullerene film reaches more than 99.7%, so, Figure 7 In the present test example, the characteristic peak appeared on the permeate side of the methylene blue solution at 24h, and for the same reason, Figure 8 In the present test example, the characteristic peak appeared on the permeate side of the copper chloride solution at 24h.

[0066] Test Example Five

[0067] Select HCl solution (0.50 nm) as the research object, methyl orange as the indicator, weigh 0.1 g of methyl orange powder, add 50 mL of deionized water, stir until completely dissolved and transfer to a 100 mL volumetric flask, dilute to volume and shake well to obtain a 0.1% methyl orange stock solution. 50mL of 0.1M HCl (pH≈1) aqueous solution is placed on the left side of the two-dimensional polymer fullerene film, and 5 drops of 0.1% methyl orange solution is added to 50mL of ultrapure water (initial pH≈6.5) on the right side. Observe and record the color change of the indicator, and evaluate whether the two-dimensional polymer fullerene film can block protons.

[0068] Please refer to Figure 10 As shown in the figure, within 5 days, the right side changes from orange to orange-red, indicating that H + ions from the left side of the filter membrane to the right side, resulting in a decrease in the pH value of the right side, and the methyl orange indicator changes from orange to orange-red, wherein, since the diameter of H + ions and the original eikon equivalent pore size (4.8 Å, i.e. 0.48 nm) of the two-dimensional polymer fullerene film are basically equal, H +Ions can slowly penetrate through the nanochannel, although the two-dimensional polymer fullerene film has nearly 100% retention rate for small organic molecules (such as methylene blue, 2.36 nm) and inorganic salt ions (such as hydrated copper ions, 0.65 nm). However, H + The ion permeability indicates that there is a size threshold for the separation selectivity, that is, when the ion diameter is close to or slightly larger than the pore diameter (H + The theoretical size is slightly larger than 0.48 nm), and it is still possible to penetrate through the "sieve effect + ion migration" mechanism, which provides the possibility for the application of the film in the fields of proton conduction and pH regulation, and also suggests that the precise matching of ion size and pore diameter needs to be considered in the strict ion retention scenario.

[0069] Test example six

[0070] NaOH solution (0.35 nm) was selected as the research object, and phenolphthalein was used as the indicator. 0.1 g of phenolphthalein was dissolved in 100 mL of 95% ethanol to obtain a 0.1% phenolphthalein ethanol solution. 50 mL of 0.1M NaOH aqueous solution (pH≈13) was placed on the left side of the two-dimensional polymer fullerene film, and 5 drops of 0.1% phenolphthalein ethanol solution was added to 50 mL of ultrapure water (initial pH≈6.5) on the right side. The change in color of the indicator was observed and recorded to evaluate whether the two-dimensional polymer fullerene film could block hydroxyl ions.

[0071] Please refer to Figure 11 In 24 hours, the right side changed from colorless to pink. It indicates that OH - Ions from the left side penetrated the filter membrane to the right side, causing the pH value on the right side to rise, and the phenolphthalein indicator changed from colorless to pink. The two-dimensional polymer fullerene film cannot completely block hydroxyl ions under strong alkaline conditions. Among them, OH - The diameter of OH

[0072] Test example seven

[0073] Through the forward osmosis experiment, the permeability of the two-dimensional polymer fullerene film to water molecules (0.28 nm) was studied, and the height difference between the two sides of the solution was observed to evaluate the water permeability of the film. A stable two-dimensional polymer fullerene film was clamped in an H-shaped transparent test tank, and Cu 2+ CuCl2 was selected as the research object because it appears blue, making it easier to observe. 45 mL of 0.1M CuCl2 aqueous solution was placed on the left side of the two-dimensional polymer fullerene film, and 45 mL of 1M sucrose aqueous solution was placed on the right side. The height difference between the two sides was observed and recorded. If a height difference appears, the height difference with time is recorded to obtain the water flux of the two-dimensional polymer fullerene film under this condition, realizing the quantification of the desalination process. At the same time, since Na + Ions have no color, and if Na+ Cu2+ ions as the research object appeared similar experimental phenomena with Cu 2+ Cu2+ ions, we can also draw the same conclusion.

[0074] As shown in Figures 12 to 13 The experimental results show that within 12 days, a height difference of 15.18 mm appears between CuCl2 aqueous solution and sucrose aqueous solution on both sides; within 12 days, a height difference of 14.31 mm appears between NaCl aqueous solution and sucrose aqueous solution on both sides; it is shown that the two-dimensional polymer fullerene film blocks Cu 2+ ions and Na + ions, but allows water molecules to pass through.

[0075] Test Example Eight

[0076] Due to the size selection of the two-dimensional fullerene film, it can block dye molecules and inorganic salt ions, but needs the passage of water molecules. The following will test the water flux. 35 ml of C60 diluent with different dilution multiples (two-dimensional polymer fullerene dispersion liquid is diluted 300-1000 times, two-dimensional polymer fullerene dispersion liquid diluted 300 times corresponds to the thickest two-dimensional fullerene film, and two-dimensional polymer fullerene dispersion liquid diluted 1000 times corresponds to the thinnest two-dimensional fullerene film) are taken to control the thickness of the two-dimensional fullerene film. The two-dimensional fullerene film with uniform surface and no obvious defects is placed on the filter (the effective area of the two-dimensional fullerene film is π), 30 ml of ultrapure water is added to the glass funnel, the vacuum filtration pump is opened, the display pressure is 0.08-0.09 MPa (because the filtration pressure will fluctuate due to the thickness of the film, the filtration pressure under different film thicknesses is recorded during the experiment), and the calculator is turned on. When the water in the glass funnel decreases to 20 ml (i.e. the volume of the permeated water is 10 ml), the vacuum filtration pump is turned off, and the filtration time is recorded. The water flux of each thickness film is calculated according to the water flux calculation formula; each thickness film is tested repeatedly for 3 times, and the average value is taken after removing the abnormal value, and finally the water flux data corresponding to different thicknesses are obtained for subsequent analysis and drawing.

[0077] The calculation formula of water flux is:

[0078] Water flux (L / (m²·h / bar)) = permeated water volume (L) ÷ (membrane effective area (m²) × operating pressure (bar) × time (h)).

[0079] As shown in Figure 13As shown, the experimental results indicate that in the different film thickness ranges corresponding to dilutions of the two-dimensional polymer fullerene dispersion by 300-1000 times, the water flux generally increases slowly with the increase of the dilution factor (decrease in film thickness), and then rises sharply when the dilution factor reaches 1000 times. Among them, the water flux corresponding to the two-dimensional fullerene film with a dilution of 400 times deviates to a certain extent because the relationship between film thickness and dilution factor is not linear. It is just that the larger the dilution factor, the thinner the film is. Secondly, the two-dimensional fullerene film is formed by stacking single-layer fullerene nanosheets, and the interlayer spacing is closely related to the dilution factor. This indicates that the interlayer spacing at this dilution factor is more conducive to the passage of water molecules. Therefore, compared with other adjacent dilution factors, the water flux deviates to a certain extent. The water flux of the two-dimensional fullerene film with a dilution of 1000 times increases sharply, indicating that when the two-dimensional fullerene film is thin enough, it will have a large water flux.

[0080] Test Example 9

[0081] This test example primarily aims to demonstrate that, as discussed in the examples, "the PTFE filter membrane itself does not possess liquid-phase separation functionality." The specific operational steps of its membrane treatment process are completely consistent with those in the examples, the main difference being that 35 ml of C60-free NMP solvent is used. The specific operational steps of its filtration process are completely consistent with those in Test Example 4, the main difference being that the membrane sandwiched in the middle is a blank PTFE membrane (i.e., the PTFE filter membrane surface does not contain a two-dimensional fullerene membrane). For the results, please refer to [link to relevant documentation]. Figure 14 ,pass Figure 14 As can be seen, after 1 hour, the methylene blue molecules in the left test cell permeated through the PTFE filter into the right test cell, thus confirming that the PTFE filter membrane itself does not have a liquid phase separation function. Combined with the experimental results in Test Example 4, it can be clearly seen that the various dye molecules and colored inorganic salts in Test Example 4 could not permeate from the left test cell to the right test cell, mainly due to the blocking effect of the two-dimensional fullerene membrane.

[0082] In summary, in the present application, the two-dimensional polymer fullerene dispersion liquid is mixed with NMP, then filtered by suction, and a two-dimensional polymer fullerene film is prepared after mild annealing treatment. The annealing treatment promotes the two-dimensional fullerene to form an AA type ordered layered structure through π-π stacking, and the original eikon pore size is about 4.8 Å, which is between water molecules and hydrated inorganic salt ions. Efficient water molecule permeation and ion interception are achieved through size screening. At the same time, the heat treatment strengthens the interlayer covalent bond and van der Waals force, improves the anti-swelling ability of the film in the solvent, and enhances the interlayer interaction to improve the stability of the film in the solvent, which can realize efficient liquid phase separation, solve the bottleneck of the easy dispersion of traditional two-dimensional membranes in liquid phase, and provide efficient and stable separation materials for seawater desalination, organic solvent nanofiltration, etc. At the same time, in the preparation process, no additional chemical pollution is introduced, the operation is simple, and it is easy to scale up, which provides convenience for the practical application of the two-dimensional polymer fullerene film.

[0083] The above only describes the preferred embodiments of the present application, and it should be pointed out that for ordinary skilled persons in the art, several improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application. The structures, devices and operation methods not specifically described and explained in the present application are implemented according to the conventional means in the art, unless otherwise specified and limited.

Claims

1. A method for preparing a water and organic solvent stable two-dimensional polymer- fullerene film, characterized by: The method comprises the following steps: St1: uniformly mixing N-methyl pyrrolidone solvent and two-dimensional polymer fullerene dispersion liquid to obtain a C60 diluent; St2: placing a substrate filter membrane containing a supporting film at the bottom on the filter head of a suction filter bottle, wetting the substrate filter membrane with an appropriate amount of N-methyl pyrrolidone solvent, starting a suction filter pump, closing the pump after 1-3 min of suction filtration, and then fixing the filter cup on the upper end of the filter head; St3: starting the suction filter pump again, pouring the C60 diluent into the filter cup, and taking out the substrate filter membrane after the C60 diluent in the filter cup completely passes through the substrate filter membrane; St4: preheating a forced air drying device to 150-180℃, placing the substrate filter membrane in the drying box for annealing treatment, taking out the substrate filter membrane after drying at 150-180℃ for 0.5-2 h, obtaining a substrate filter membrane covered with a two-dimensional polymer fullerene film, and peeling off the supporting film at the bottom of the substrate filter membrane to obtain a two-dimensional polymer fullerene film containing the substrate filter membrane.

2. The method for preparing a water and organic solvent stable two-dimensional polymer fullerene film according to claim 1, characterized in that: In the St1, the volume ratio of the two-dimensional polymer fullerene dispersion liquid to the N-methyl pyrrolidone solvent is 1:

99.

3. The method according to claim 1, wherein the method is characterized by: The substrate filter membrane is a hydrophilic polytetrafluoroethylene filter membrane.

4. The method according to claim 3, wherein the method is characterized by: The pore size of the hydrophilic polytetrafluoroethylene filter membrane is 0.1-0.3 μm.

5. A two-dimensional polymer fullerene film produced by the method for producing a two-dimensional polymer fullerene film which is dual-stable in water and an organic solvent according to any one of claims 1 to 4, characterized by: The two-dimensional polymer fullerene film has a pristine Eckon structure, and the equivalent pore size is 4.8 Å.

6. Use of a two-dimensional polymerfullerene film as claimed in claim 5 in liquid phase membrane separations, characterized by: The two-dimensional polymer fullerene film is used for separating small organic molecules, inorganic salt ions, or water molecules. The two-dimensional polymer fullerene film is used for separating small organic molecules, inorganic salt ions, or water molecules.

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