A method for constructing an ultrathin polyarylethersulfone membrane containing arranged cyclodextrins within an interface confinement

Abstract

This invention provides a method for constructing an ultrathin polyarylene ether sulfone (PAES-COOH) membrane containing aligned cyclodextrins within an interface confinement, belonging to the field of polyarylene ether sulfone membrane preparation technology. The method involves subjecting PAES-COOH containing carboxyphenyl side groups to an acylation reaction to obtain an acylated PAES-COOH solution. β-cyclodextrin is then added dropwise to the aforementioned acylated PAES-COOH solution to react and obtain PAES-CD powder. The PAES-CD powder is dissolved in a good solvent and then diluted with a low surface tension solvent to prepare a membrane-forming solution. The membrane-forming solution is then dropped onto a water surface, where the droplets spontaneously spread, inducing the β-CD molecules on the PAES-CD side chains to align parallel along the liquid-liquid interface, forming an ultrathin polymer membrane with controllable thickness. This method can obtain ultrathin polymer membranes with uniform angstrom-level pores and excellent ion selectivity.

Description

Technical Field

[0001] This invention belongs to the field of polyarylene ether sulfone membrane preparation technology, specifically relating to a method for constructing an ultrathin polyarylene ether sulfone membrane containing arranged cyclodextrins within an interface confinement. Background Technology

[0002] Existing methods for preparing ion-selective polymer membranes mainly include: 1. Interfacial polymerization: Two reactive monomers are dissolved separately in immiscible solvents, and polymerization occurs at the interface between the two phases to form an ultrathin layer. This method can prepare cross-linked polymer networks, but the reaction process is rapid and random, making it difficult to precisely control the pore structure. The resulting membrane has an uneven pore size distribution and cannot achieve ion sieving with angstrom-level precision.

[0003] 2. Spin coating: A polymer solution is dropped onto a substrate, and the solution is spread by high-speed rotation. After the solvent evaporates, a film is formed. This method is simple and easy to implement, but it relies solely on passive shear force and cannot induce ordered molecular arrangement. The macrocyclic molecules (such as cyclodextrins) in the resulting film are randomly oriented, making it difficult to form long-range ordered transport channels, resulting in poor ion selectivity.

[0004] 3. Solution casting method: The polymer solution is cast onto a plate, and the solvent evaporates to form a film. The film obtained by this method is relatively thick (usually >100 nm) and has a disordered internal structure, which is not conducive to efficient ion transport.

[0005] The above methods generally have the following drawbacks: It is impossible to achieve the controllable construction of ordered structures within the membrane at the ultrathin scale; it is difficult to obtain uniform angstrom-level pores; the process is complex or has poor scalability, which is not conducive to industrial applications.

[0006] Therefore, there is an urgent need to develop a simple and scalable membrane fabrication method that can induce the ordered arrangement of macrocyclic molecules and form uniform angstrom-level pores in ultrathin polymer films. Summary of the Invention

[0007] The purpose of this invention is to solve the problem that existing methods cannot achieve the controllable construction of ordered structures within membranes at the ultrathin scale, thereby providing a method for constructing ultrathin polyarylene ether sulfone membranes containing arranged cyclodextrins within an interface confinement. This method can obtain ultrathin polymer membranes with uniform angstrom-level pores and excellent ion selectivity.

[0008] The present invention achieves the above objective through the following steps: This invention provides a method for constructing an ultrathin polyarylethersulfone membrane containing arranged cyclodextrins within an interface confinement, comprising: Step 1: Dissolve the polyarylene ether sulfone PAES-COOH containing a carboxylphenyl side group in an organic solvent, add thionyl chloride to carry out an acyl chloride reaction, and obtain an acyl chloride PAES-COOH solution. Dissolve β-cyclodextrin in the solvent, add an acid-binding agent, and add it dropwise to the above acyl chloride PAES-COOH solution under ice bath conditions. React to obtain PAES-CD powder. The structure of the polyarylene ether sulfone PAES-COOH containing a carboxylphenyl side group is shown in Formula 1. Formula 1, In Equation 1, n = 0.4 - 0.8; Step 2: Dissolve the PAES-CD powder obtained in Step 1 in a good solvent, and then dilute it with a low surface tension solvent to prepare a film-forming solution; Step 3: Add the film-forming droplet prepared in Step 2 to the water surface. The droplet spreads spontaneously on the water surface. During the spreading process, shear flow force is generated inside the droplet, which induces the β-CD molecules on the PAES-CD side chain to align parallel along the liquid-liquid interface. After the solvent has completely evaporated, an ultrathin polymer film with controllable thickness is formed on the water surface.

[0009] Preferably, the temperature of the acyl chloride reaction in step one is 40-60℃ and the time is 3-6 h.

[0010] Preferably, the acid-binding agent in step one is triethylamine.

[0011] Preferably, the reaction temperature in step one is 0°C and the reaction time is 2-4 h.

[0012] Preferably, the molar ratio of polyarylene sulfone containing carboxyphenyl side groups, thionyl chloride, and β-cyclodextrin in step one is 10:12:15.

[0013] Preferably, the good solvent in step two is DMSO, and the low surface tension solvent is dichloromethane.

[0014] Preferably, the volume ratio of the good solvent and the low surface tension solvent in step two is 1:(5-10).

[0015] Preferably, the concentration of the film-forming solution in step two is 5-15 mg / mL.

[0016] Preferably, the droplets in step three are placed on the water surface at a height of 3-10 mm.

[0017] Preferably, the thickness of the ultrathin polymer film described in step three is 6-24 nm.

[0018] Compared with existing technologies, it has the following beneficial effects: 1. Simple and efficient process: The polymer solution is simply dropped onto the water surface and spreads spontaneously by utilizing the surface tension difference. No complicated equipment is required and the film formation speed is fast (it can be completed within a few minutes).

[0019] 2. Ordered and controllable structure: By utilizing the shear flow force generated during the spreading process, β-CD molecules were successfully induced to align parallel to the interface, forming a long-range ordered structure within the film. XRD and TEM confirmed that the lattice fringe spacing was 2.7 Å, corresponding to angstrom-level pores.

[0020] 3. Ultra-thin and uniform film thickness: The resulting film thickness can be as low as 6 nm, and the surface roughness is <3 nm, which is far superior to traditional methods such as spin coating.

[0021] 4. Excellent ion selectivity: Due to the formation of ordered channels, this membrane exhibits excellent ion selectivity for K+. + / Na + It exhibits voltage-gated selectivity with a selectivity ratio as high as 108.15, which is about 50 times higher than that of existing polymer films.

[0022] 5. High scalability: This method can be scaled up to continuous film fabrication to prepare large-area uniform films, and has the potential for industrial application. Attached Figure Description

[0023] Figure 1 This is a synthetic route diagram for PAES-CD of the present invention.

[0024] Figure 2 This is a schematic diagram of the PAES-CD ultrathin film prepared by the interfacial superspreading of the present invention.

[0025] Figure 3 This is a schematic diagram illustrating the mechanism by which shear flow forces induce β-CD alignment during droplet spreading in this invention.

[0026] Figure 4 This is a schematic diagram of the large-area continuous film-forming device of the present invention.

[0027] Figure 5 This is an AFM height diagram of the PAES-CD ultrathin film of the present invention.

[0028] Figure 6 This is a surface roughness diagram of the PAES-CD ultrathin film of the present invention.

[0029] Figure 7 The images shown are TEM images and magnified views of the PAES-CD ultrathin films prepared in Example 3 of this invention.

[0030] Figure 8 This is an XRD diffraction peak image of the PAES-CD ultrathin film of the present invention.

[0031] Figure 9(a) Top and side views of the ordered molecular packing of cyclodextrin; (b) Dye rejection of PAES-CD and PAES-COOH ultrafilms, where gray shading indicates the rejection rate of dye molecules (≥90%).

[0032] Figure 10 This invention relates to the polymerization of a polymer film in a single salt solution (10 mV) under an applied voltage (200 mV). -4 The ion concentration and ion selectivity diagram on the pure water side after ion separation in M) for 2 hours.

[0033] Figure 11 This is a schematic diagram showing the thickness and roughness of different regions of the large-area PAES-CD ultrathin film of the present invention. Detailed Implementation

[0034] This invention provides a method for constructing an ultrathin polyarylethersulfone membrane containing arranged cyclodextrins within an interface confinement, comprising: Step 1: Dissolve polyarylene ether sulfone (PAES-COOH) containing carboxylphenyl side groups in an organic solvent, preferably dimethyl sulfoxide (DMSO). Add thionyl chloride (SOCl2) to carry out an acyl chloride reaction. The reaction temperature is preferably 40-60℃, and the reaction time is preferably 3-6 h, to obtain an acyl chloride PAES-COOH solution. Dissolve β-cyclodextrin (β-CD) in a solvent, preferably DMSO, and add an acid-binding agent, preferably triethylamine. Add the solution dropwise to the above acyl chloride PAES-COOH solution under ice bath conditions. React for 2-4 h to obtain a PAES-CD reaction solution. Pour the reaction solution into anhydrous ethanol to precipitate a solid, wash and dry to obtain PAES-CD powder. The molar ratio of polyarylene ether sulfone containing carboxylphenyl side groups, thionyl chloride, and β-cyclodextrin is preferably 10:12:15, and the amount of acid-binding agent added is preferably 10% of the mass of β-cyclodextrin. The synthetic route is shown below. Figure 1 As shown in Formula 1, the polyarylene ether sulfone (PAES-COOH) containing a carboxylphenyl side group has the following structure: Formula 1, In Equation 1, n = 0.4 - 0.8; Step 2: Dissolve the PAES-CD powder obtained in Step 1 in a good solvent, preferably DMSO, and then dilute it with a low surface tension solvent, preferably dichloromethane, to prepare a film-forming solution; the volume ratio of the good solvent to the low surface tension solvent is preferably 1:(5-10); the concentration of the film-forming solution is preferably 5-15 mg / mL.

[0035] Step 3: Add the film-forming solution prepared in Step 2 to the water surface, preferably at a height of 3-10 mm. The droplets spontaneously spread on the water surface due to the surface tension difference (surface tension of the film-forming solution < surface tension of water). During spreading, shear flow forces are generated inside the droplets, inducing β-CD molecules on the PAES-CD side chains to align parallel to each other along the liquid-liquid interface. After the solvent has completely evaporated, preferably by evaporation at room temperature for 5-15 minutes, an ultrathin polymer film with controllable thickness is formed on the water surface. The thickness of the ultrathin polymer film is preferably 6-24 nm. A schematic diagram of the mechanism by which shear flow forces induce β-CD alignment during droplet spreading is shown below. Figure 3 As shown.

[0036] The ultrathin films prepared above are transferred to desired substrates (such as silicon wafers, PVDF films, copper meshes, etc.) for subsequent characterization or application. The thickness and order of the film can be controlled by adjusting parameters such as the concentration of the film-forming solution, the drop height, and the solvent ratio, as needed. A schematic diagram of the interfacial superspreading preparation of PAES-CD ultrathin films according to this invention is shown below. Figure 2 As shown.

[0037] The method of this invention can achieve large-area continuous film formation. Specifically, it preferably employs a multi-injector system, where multiple syringes are arranged side-by-side (approximately 1 cm apart) to simultaneously extrude the film-forming liquid. During extrusion, the water-based substrate is slowly moved perpendicular to the syringe arrangement direction to achieve large-area continuous film formation (e.g., 3 cm × 5 cm). A schematic diagram of the large-area continuous film formation device is shown below. Figure 4 As shown.

[0038] The present invention will be further described in detail below with reference to specific embodiments. All raw materials involved in the embodiments are commercially available.

[0039] Example 1: Synthesis of PAES-CD Polyacrylamide (PPL, 2.56 g, 0.008 mmol), DBP (5.95 g, 0.032 mmol), anhydrous K₂CO₃ (7.18 g, 0.052 mmol), NMP (78 mL), and toluene (26 mL) were dissolved in a three-necked flask under nitrogen protection. The mixture was refluxed at 145 °C for 1.5 h to promote dehydration, during which toluene removed water from the system, and potassium carbonate phosphated the hydroxyl groups. Finally, DPS (10 g, 0.04 mmol) was added, and the mixture was stirred at 145 °C for 1.5 h to promote dehydration. The mixture was then gradually heated to 200 °C to evaporate excess toluene. After the toluene had completely evaporated, the reaction was continued for 3 hours until the solution thickened. The viscous solution was injected into acidic deionized water while hot to obtain green polymer strips. After the strips were allowed to stand overnight, they were pulverized into polymer particles using a high-speed grinder. The obtained polymer was washed three times with boiling deionized water and ethanol to finally obtain the carboxyl-containing polymer PAES-COOH.

[0040] PAES-COOH (40% carboxyl content, 200 mg) was dissolved in 10 mL DMSO, and SOCl2 (13 mg) was added. The reaction was carried out at 50 °C for 5 h to obtain an acyl chloride PAES-COOH solution. β-CD (1 g) was dissolved in 10 mL DMSO, and triethylamine (28 mg) was added. The above acyl chloride PAES-COOH solution was slowly added dropwise under ice bath conditions, and the reaction was stirred for 3 h. The reaction solution was poured into anhydrous ethanol to precipitate a solid, which was washed three times with anhydrous ethanol and dried under vacuum at 30 °C for 12 h to obtain PAES-CD powder.

[0041] Example 2: Preparation of film-forming solutions of different concentrations The PAES-CD powder prepared in Example 1 was dissolved in DMSO to prepare a 100 mg / mL concentrate. The concentrate was diluted with CH2Cl2 to prepare film-forming solutions with concentrations of 5 mg / mL, 10 mg / mL, and 15 mg / mL, respectively (DMSO: CH2Cl2 = 1:10, volume ratio).

[0042] Example 3: Construction of ultrathin films by interface confinement Using a dropper, 1 drop (approximately 50 μL) of the film-forming solution prepared in Example 2 at a height of 5 mm above the water surface was added. The droplet spread rapidly, and after standing for 10 min to allow the solvent to evaporate, an ultrathin film was formed on the water surface. The film was then transferred to a silicon wafer for testing and characterization.

[0043] Figure 5 This is an AFM height map of the PAES-CD ultrathin film prepared in Example 3 of this invention. Figure 6 This is a surface roughness diagram of the PAES-CD ultrathin film prepared in Example 3 of the present invention. It can be seen that the thickness measured by AFM is 6.24 nm, and the roughness is 2.4 nm.

[0044] Figure 7 These are TEM images and magnified views of the PAES-CD ultrathin film prepared in Example 3 of this invention, wherein... Figure 7 a is a TEM image of the PAES-CD ultrathin film; Figure 7 b is a magnified view of the crystalline region in the TEM image of the PAES-CD ultrathin film, and the inset in the upper left corner is the selected area electron diffraction pattern of the ultrathin film. It can be seen that the PAES-CD ultrathin film prepared by this method has an ordered structure.

[0045] Figure 9 For Example 3 of the present invention, (a) a top view and a side view of the ordered molecular stacking of cyclodextrin; (b) the dye rejection rate of PAES-CD and PAES-COOH ultrafilms, wherein the gray shading represents the rejection rate of dye molecules (≥90%).

[0046] Comparative Example 1: Preparation of PAES-CD spin-coated thick film PAES-CD was dissolved in dimethyl sulfoxide to prepare a 100 mg / mL solution. The spin coater was set to slow speed: 300 r / min, 15 seconds; fast speed: 3000 r / min, 30 seconds. The spin-coated glass plates were placed in an oven at 60°C overnight to dry the solvent, forming a PAES-CD thick film (83 nm thick).

[0047] Comparative Example 2: Preparation of PAES-COOH Interface Confined Ultrathin Films PAES-COOH powder was dissolved in DMSO to prepare a 100 mg / mL concentrate. The concentrate was diluted with CH2Cl2 to prepare film-forming solutions with concentrations of 5 mg / mL, 10 mg / mL, and 15 mg / mL (DMSO: CH2Cl2 = 1:10, volume ratio). Using a dropper, one drop (approximately 50 μL) of the 5 mg / mL film-forming solution was added to the water at a height of 5 mm above the surface. The droplet spread rapidly, and after standing for 10 min to allow the solvent to evaporate, an ultrathin film formed on the water surface.

[0048] Comparative Example 3: Preparation of PAES-COOH spin-coated thick film PAES-COOH was dissolved in dimethyl sulfoxide to prepare a 100 mg / mL solution. The spin coater was set to slow speed: 300 r / min, 15 seconds; fast speed: 3000 r / min, 30 seconds. The spin-coated glass plate was placed in an oven and dried overnight at 60°C to form a PAES-COOH thick film (85 nm thick).

[0049] Figure 8 The XRD diffraction peak patterns of the PAES-CD ultrathin film prepared in Example 3 of the present invention and the films prepared in Comparative Examples 1-3 are shown. It can be seen that neither the ultrathin film prepared by spin coating nor the one without grafted macroring has X-ray diffraction peaks, that is, it does not have an ordered structure.

[0050] Example 4: Preparation of films of different thicknesses Example 3 was repeated using film-forming solutions of 5 mg / mL, 10 mg / mL, and 15 mg / mL, respectively, to obtain ultrathin films with thicknesses of 6.24 nm, 13.48 nm, and 21.64 nm (measured by AFM), with roughness increasing slightly with thickness.

[0051] Example 5: Large-area continuous film formation Three syringes were fixed side-by-side, 1 cm apart, each filled with 5 mg / mL of film-forming solution. A water substrate was placed beneath the syringes and moved uniformly at 0.5 cm / s. Simultaneously, the film-forming solution was extruded, forming a continuous film on the water surface, ultimately yielding a large-area film of 3 cm × 5 cm. Nine points were uniformly selected on the film for AFM testing; the thickness deviation was <±1 nm, and the roughness was <3 nm. Figure 11 As shown.

[0052] Example 6: Ion Selectivity Test The PAES-CD ultrathin film obtained in Example 3 was transferred to a porous substrate and sandwiched in an electrolytic cell. (10 on one side) -4 M KCl solution, add deionized water to the other side, and insert an Ag / AgCl electrode. Apply a step voltage (10⁻⁵ V to 3 V), record the IV curve, and measure K. + Threshold voltage 160 mV, Na + Threshold voltage 350 mV.

[0053] like Figure 10 As shown, Figure 10 This invention relates to the polymerization of a polymer film in a single salt solution (10 mV) under an applied voltage (200 mV). -4 After separating ions in M) for 2 hours, ICP-MS analysis of the ion concentration and ion selectivity on the pure water side showed that the ion selectivity of the PAES-CD ultrafilm was 10⁸, significantly higher than that of the membranes prepared in Comparative Examples 1, 2, and 3. This demonstrates that the PAES-CD ultrafilm with its ordered structure exhibits significant ion selectivity.

Claims

1. A method for constructing an ultrathin polyarylethersulfone membrane containing arranged cyclodextrins within an interface confinement, characterized in that, include: Step 1: Dissolve the polyarylene ether sulfone PAES-COOH containing a carboxylphenyl side group in an organic solvent, add thionyl chloride to carry out an acyl chloride reaction, and obtain an acyl chloride PAES-COOH solution. Dissolve β-cyclodextrin in the solvent, add an acid-binding agent, and add it dropwise to the above acyl chloride PAES-COOH solution under ice bath conditions. React to obtain PAES-CD powder. The structure of the polyarylene ether sulfone PAES-COOH containing a carboxylphenyl side group is shown in Formula 1. Formula 1, In Equation 1, n = 0.4 - 0.8; Step 2: Dissolve the PAES-CD powder obtained in Step 1 in a good solvent, and then dilute it with a low surface tension solvent to prepare a film-forming solution; Step 3: Add the film-forming droplet prepared in Step 2 to the water surface. The droplet spreads spontaneously on the water surface. During the spreading process, shear flow force is generated inside the droplet, which induces the β-CD molecules on the PAES-CD side chain to align parallel along the liquid-liquid interface. After the solvent has completely evaporated, an ultrathin polymer film with controllable thickness is formed on the water surface.

2. The method for constructing an ultrathin polyarylene ether sulfone membrane containing arranged cyclodextrins within an interface confinement according to claim 1, characterized in that, The temperature of the acyl chloride reaction described in step one is 40-60℃, and the time is 3-6 h.

3. The method for constructing an ultrathin polyarylene ether sulfone membrane containing arranged cyclodextrins within an interface confinement according to claim 1, characterized in that, The acid-binding agent mentioned in step one is triethylamine.

4. The method for constructing an ultrathin polyarylene ether sulfone membrane containing arranged cyclodextrins within an interface confinement according to claim 1, characterized in that, The reaction temperature in step one is 0℃, and the reaction time is 2-4 h.

5. The method for constructing an ultrathin polyarylene ether sulfone membrane containing arranged cyclodextrins within an interface confinement according to claim 1, characterized in that, The molar ratio of polyarylene ether sulfone containing carboxyphenyl side groups, thionyl chloride, and β-cyclodextrin in step one is 10:12:

15.

6. The method for constructing an ultrathin polyarylene ether sulfone membrane containing arranged cyclodextrins within an interface confinement according to claim 1, characterized in that, The good solvent mentioned in step two is DMSO, and the low surface tension solvent is dichloromethane.

7. The method for constructing an ultrathin polyarylethersulfone membrane containing arranged cyclodextrins within an interface confinement according to claim 1, characterized in that, The volume ratio of the good solvent and the low surface tension solvent mentioned in step two is 1:(5-10).

8. The method for constructing an ultrathin polyarylethersulfone membrane containing arranged cyclodextrins within an interface confinement according to claim 1, characterized in that, The concentration of the film-forming solution described in step two is 5-15 mg / mL.

9. The method for constructing an ultrathin polyarylene ether sulfone membrane containing arranged cyclodextrins within an interface confinement according to claim 1, characterized in that, The droplets mentioned in step three are placed on the water surface at a height of 3-10 mm.

10. The method for constructing an ultrathin polyarylethersulfone membrane containing arranged cyclodextrins within an interface confinement according to claim 1, characterized in that, The thickness of the ultrathin polymer film described in step three is 6-24 nm.

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