A hydrophilic fiber membrane, a hydrophilic-hydrophobic Janus membrane and a preparation method thereof
By introducing copper nanoparticles into the TPU spinning solution and chemically modifying them, a hydrophilic Janus membrane with strong interfacial adhesion was prepared, solving the problems of high material composite difficulty and weak interfacial adhesion in the existing technology, and achieving high water absorption and stable air permeability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ZHENGZHOU UNIV
- Filing Date
- 2023-06-30
- Publication Date
- 2026-07-24
AI Technical Summary
Existing Janus membranes face challenges in material composite preparation and interfacial adhesion, and traditional methods fail to fully utilize the hydrophilic properties of copper mesh.
Copper nanoparticles were introduced into the TPU spinning solution, and conical micro-nano structures were grown in situ on the TPU fiber membrane through electrospinning and chemical modification to form a hydrophilic fiber membrane. The membrane was then composited with a hydrophobic TPU fiber membrane using the same matrix material through an asymmetric preparation method to enhance interfacial adhesion.
The Janus membrane exhibits strong interfacial adhesion, with the hydrophilic side having a higher liquid osmotic pressure than the hydrophobic side, a water absorption rate as high as 2340%, and stable air permeability under a 20cm water column pressure. The preparation process is simple.
Smart Images
Figure CN117482762B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of Janus membrane preparation, and in particular to a hydrophilic fiber membrane, a hydrophilic-hydrophobic Janus membrane, and a method for preparing the same. Background Technology
[0002] With the advancement of science, water treatment membranes have found wide applications in daily life. In recent years, Janus membranes have attracted considerable attention in the field of water treatment membrane research due to their asymmetric wettability. Existing literature also includes the fabrication of gradient unidirectional permeation Janus membranes with continuous directional water transport capabilities using in-situ grown conical micro / nanostructured copper mesh as an imprinting template. The interfacial adhesion of the Janus membrane has been enhanced by combining electrospinning and microimprinting techniques. However, the in-situ grown conical micro / nanostructure is limited by the copper mesh itself, serving only as an imprinting template, and its inherent hydrophilic properties are not fully utilized.
[0003] Janus membranes prepared using asymmetric methods are typically classified as two-layer or three-layer composite membranes, with the hydrophilic and hydrophobic properties of each layer largely determined by the inherent properties of the materials themselves. However, traditional asymmetric methods often result in Janus membranes that are difficult to composite between different materials or exhibit weak interfacial adhesion. Summary of the Invention
[0004] This invention proposes a hydrophilic fiber membrane, a hydrophilic-hydrophobic Janus membrane, and their preparation methods. In the TPU spinning solution, metallic copper nanoparticles are introduced to grow conical micro-nano structures in situ to induce hydrophilic modification of the TPU fiber membrane. The Janus membrane obtained by using the same matrix material through an asymmetric preparation method has strong interfacial adhesion and the preparation process is simple.
[0005] The technical solution of the present invention is implemented as follows: a hydrophilic fiber membrane, comprising a composite porous membrane composed of TPU fibers, wherein the TPU fibers are in an expanded state and contain hydrophilic Cu(OH)2.
[0006] A method for preparing a hydrophilic fiber membrane includes the following steps:
[0007] (1) TPU and cleaned copper nanoparticles were stirred and dispersed in N,N-dimethylformamide (DMF) to obtain Cu / TPU spinning solution; the Cu / TPU spinning solution was electrospun to obtain Cu / TPU fiber membrane;
[0008] (2) The Cu / TPU fiber membrane was placed in a mixed aqueous solution of NaOH and K2S2O8 for reaction. After the reaction was completed, it was washed and dried to obtain the affinity fiber membrane.
[0009] Further, in step (1), the Cu / TPU spinning solution includes 0.4-1.2g of copper nanoparticles, 75.6g of N,N-dimethylformamide and 13.34g of TPU.
[0010] Furthermore, the copper nanoparticles have a particle size of 50nm-100nm.
[0011] Further, in step (2), the concentration of NaOH in the mixed aqueous solution is 2.5 mol / L and the concentration of K2S2O8 is 0.1 mol / L; the reaction time is 2-6 hours.
[0012] Further, in step (1), the copper nanoparticles are cleaned as follows: the copper nanoparticles are immersed in acetone for ultrasonic cleaning, then immersed in deionized water for ultrasonic cleaning to remove surface dirt, and finally dried.
[0013] A hydrophilic fiber membrane is prepared using the aforementioned preparation method.
[0014] A hydrophilic-hydrophobic Janus membrane includes a hydrophobic TPU fiber membrane, on which a hydrophilic fiber membrane is deposited. The hydrophilic fiber membrane is a composite porous membrane composed of TPU fibers, the TPU fibers are in an expanded state, and hydrophilic Cu(OH)2 is wrapped in the TPU fibers.
[0015] A method for preparing a hydrophilic-hydrophobic Janus membrane includes the following steps:
[0016] 1) TPU is added to N,N-dimethylformamide (DMF) to obtain a TPU spinning solution; the TPU spinning solution is electrospun to obtain a TPU fiber film;
[0017] 2) TPU and cleaned copper nanoparticles were stirred and dispersed in N,N-dimethylformamide (DMF) to obtain Cu / TPU spinning solution; the Cu / TPU spinning solution was electrospun to form Cu / TPU fiber membrane on TPU fiber membrane, thus obtaining two-layer composite fiber membrane;
[0018] 3) The two composite fiber membranes were placed in a mixed aqueous solution of NaOH and K2S2O8 for reaction. After the reaction was completed, the membranes were washed and dried to obtain a hydrophilic and hydrophobic Janus membrane.
[0019] The beneficial effects of this invention are:
[0020] This invention introduces copper nanoparticles into a TPU spinning solution to grow a conical micro / nano structure in situ, thereby inducing hydrophilic modification of the TPU fiber membrane. A Janus membrane with hydrophilic / hydrophobic properties is prepared by compositing two TPU fiber membranes. The Janus membrane obtained by using the same matrix material TPU through an asymmetric preparation method has strong interfacial adhesion and the preparation process is simple.
[0021] This invention chemically modifies hydrophobic TPU fiber membranes to obtain hydrophilic TPU fiber membranes. The chemical modification principle is as follows: Cu + 2NaOH + K₂S₂O₈ = Cu(OH)₂ + Na₂SO₄ + K₂SO₄. After chemical modification, the contact angle of the TPU fiber membrane decreases from 113° to 68°, corresponding to a water absorption rate of up to 2340% of its own weight, thus making the originally hydrophobic TPU fiber membrane hydrophilic, successfully inducing hydrophilic modification of the TPU fiber membrane.
[0022] The hydrophilic and hydrophobic Janus membrane prepared by this invention can withstand a water column pressure of 20 cm and a pressure of 0.05 kg / cm². 3 It can still maintain stable and continuous gas permeability under high gas flux, and after chemical treatment, the hydrophilic liquid osmotic pressure in the Janus membrane is greater than that on the hydrophobic liquid osmotic pressure. Attached Figure Description
[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0024] Figure 1 The mechanical properties test diagram shows the unmodified fiber membrane.
[0025] Figure 2 The graph shows the water contact angle performance of fiber membranes under different chemical modification times.
[0026] Figure 3 The graph shows the water absorption performance of fiber membranes under different chemical modification times.
[0027] Figure 4 Figures showing liquid diffusion tests on different sample surfaces;
[0028] Figure 5 SEM images of TPU fiber membranes prepared for different chemical modification times in Comparative Example 1;
[0029] Figure 6 SEM images of hydrophilic fiber membranes prepared at different chemical modification times in Example 2;
[0030] Figure 7 This is a graph showing the liquid osmotic pressure test results on both sides of the hydrophilic and hydrophobic Janus membrane under different chemical modification times in Example 5.
[0031] Figure 8 The air permeability of the hydrophilic-hydrophobic Janus membrane (chemically treated for 6 hours) under different air fluxes in Example 5 is shown. Detailed Implementation
[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0033] A method for preparing an aqueous fiber membrane includes the following steps:
[0034] (1) Clean the copper nanoparticles. The cleaning method is as follows: Soak the copper nanoparticles in acetone and sonicate for 30 min, then soak the copper nanoparticles in deionized water and sonicate for 30 min to remove surface dirt, and then put them in an oven at 50℃ for 5 h to dry; the particle size of the copper nanoparticles is 50nm-100nm.
[0035] Cleaned copper nanoparticles and TPU (thermoplastic polyurethane) were added to DMF and stirred continuously at room temperature for 10 hours to obtain a Cu / TPU spinning solution; the Cu / TPU spinning solution was electrospun to obtain a Cu / TPU fiber membrane.
[0036] (2) The Cu / TPU fiber membrane was placed in a mixed aqueous solution of 2.5 mol / L NaOH and 0.1 mol / L K2S2O8 for chemical modification. After the reaction was completed, it was washed and dried to obtain the affinity fiber membrane.
[0037] Table 1 Electrospinning solution ratio parameters and chemical modification time
[0038] C0 Comparative Example 1 13.34 0.00 75.60 0、2、4、6 C1 Example 1 13.34 0.40 75.60 0、2、4、6 C2 Example 2 13.34 0.80 75.60 0、2、4、6 C3 Example 3 13.34 1.20 75.60 0、2、4、6
[0039] Mechanical properties were tested on the Cu / TPU fiber membranes (unmodified) prepared in Examples 1-3 and the TPU fiber membrane (unmodified) prepared in Comparative Example 1. Figure 1 As shown, compared with the pure TPU fiber membrane, the Young's modulus of the fiber membranes in Examples 1 and 2 increased. The Young's modulus of the fiber membrane in Example 3 was not significantly different from that of the pure TPU fiber membrane, but the elongation at break and tensile strength of the fiber membrane in Example 3 showed a significant decreasing trend.
[0040] In Examples 1-2 and Comparative Example 1, step (2) was performed for different reaction times, and the resulting fiber membranes were tested for water contact angle performance, such as... Figure 2 As shown, the reaction times were 0h, 2h, 4h, and 6h. (a) Comparative Example 1: TPU fiber membrane C0 after chemical treatment; (b) Hydrophilic fiber membrane C1 of Example 1; (c) Hydrophilic fiber membrane C2 of Example 1. Figure 2 (a) It can be seen that, in Comparative Example 1, although the contact angle decreases slightly with increasing reaction time, the decrease is small, and the overall hydrophobicity remains stable, proving that the hydrophobicity of pure TPU fiber membrane is not significantly affected after chemical treatment. Figure 2 (b) It can be seen that the contact angle of the C1 fiber membrane decreases with increasing chemical modification time, but the decrease is small, reaching a minimum of 104.75° when the chemical modification time reaches 6 hours. Figure 2 (c) It can be seen that the contact angle of the C2 fiber membrane decreases significantly with the increase of chemical modification time. The lowest contact angle value is 68° when the chemical modification time reaches 6h. The contact angle of the C2 fiber membrane decreases significantly, making the TPU fiber membrane, which originally exhibits hydrophobic properties, hydrophilic.
[0041] In Examples 1-2 and Comparative Example 1, step (2) was performed for different reaction times, and the water absorption performance of the chemically modified fiber membrane was tested (G1 and G2 are the masses of the membrane before and after water absorption, respectively). Figure 3 As shown, the reaction times were 0h, 2h, 4h, and 6h. (a) Comparative Example 1 TPU fiber membrane C0 after chemical treatment; (b) Hydrophilic fiber membrane C1 of Example 1; (c) Hydrophilic fiber membrane C2 of Example 1.
[0042] from Figure 3 It can be seen that the C0 fiber membrane has poor water absorption performance because it does not contain copper nanoparticles and is inherently hydrophobic. The C1 fiber membrane, with the addition of copper nanoparticles and chemical treatment, shows a slight improvement in water absorption performance with increasing chemical modification time, which corresponds to its water contact angle test results. The C2 fiber membrane exhibits a significant improvement in water absorption performance because its water contact angle decreases significantly with increasing chemical modification time. Similarly, its water absorption performance reaches its peak after 6 hours of chemical treatment, with a water absorption rate as high as 2340% of its own weight.
[0043] Figure 4 Liquid diffusion tests were conducted on the surfaces of different samples: (a) TPU fiber membrane prepared in Comparative Example 1 (untreated); (b) Cu / TPU fiber membrane prepared in Example 2; (c) hydrophilic fiber membrane prepared in Example 2 (treated chemically for 6 hours). Figure 4As shown in (a), when several droplets are dropped onto the surface of a pure TPU fiber membrane, the droplets do not wet the fiber membrane as time goes on because the TPU fiber membrane itself is hydrophobic. They can maintain their original shape and do not spread or diffuse on the membrane surface. Figure 4 As shown in (b), the copper nanoparticle-free fiber membrane exhibits the same hydrophobicity as the CO fiber membrane when droplets fall on its surface. The droplets maintain their original morphology and do not wet the fiber membrane, proving that the addition of copper nanoparticles does not affect the hydrophobicity of the TPU fiber membrane itself. However, from... Figure 4 (c) It was observed that when the droplets fell onto the hydrophilic fiber membrane after 6 hours of chemical treatment, the droplets quickly wetted the surface of the fiber membrane, and the fiber membrane as a whole exhibited good hydrophilicity. This is because during the chemical treatment, the copper nanoparticles in the fiber membrane generated hydrophilic substances, which made the fiber membrane change from hydrophobic to hydrophilic.
[0044] Figure 5 SEM images of TPU fiber membranes prepared for different chemical modification times in Comparative Example 1, with reaction times of 0 h, 2 h, 4 h, and 6 h. Figure 5 As can be seen, although the TPU fiber membrane was chemically treated with the strongly alkaline solution NaOH, the morphology of the TPU fiber did not change significantly with the increase of chemical modification time, proving that the chemical treatment process does not cause significant damage to the fiber.
[0045] Figure 6 SEM images of hydrophilic fiber membranes prepared for different chemical modification times in Example 2, with reaction times of 0 h, 2 h, 4 h, and 6 h. Figure 6 As can be seen, the fibers in the hydrophilic fiber membranes after 4h and 6h of chemical treatment are in a swollen form. This is because the fibers are encapsulated with hydrophilic substances generated during the chemical treatment. The overall distribution of fibers in the fiber membranes composed of swollen fibers is still relatively uniform, and the overall morphology has not changed significantly.
[0046] A method for preparing a hydrophilic-hydrophobic Janus membrane includes the following steps:
[0047] (1) 13.34g TPU was added to 75.6g DMF and stirred continuously at room temperature for 10h to obtain TPU spinning solution; the TPU spinning solution was transferred to a 10ml syringe with a metal needle with an inner diameter of 0.6mm for electrospinning, the spinning time was controlled at 4h, and the spinning distance and voltage were controlled at 16cm and 15kV respectively to obtain TPU fiber membrane;
[0048] (2) Clean the copper nanoparticles. The cleaning method is as follows: Soak the copper nanoparticles in acetone and sonicate for 30 min, then soak the copper nanoparticles in deionized water and sonicate for 30 min to remove surface dirt, and then put them in an oven at 50℃ for 5 h to dry; the particle size of the copper nanoparticles is 50nm-100nm.
[0049] 0.8g of cleaned copper nanoparticles and 13.34g of TPU were added to 75.6g of DMF and stirred continuously at room temperature for 10h to obtain a Cu / TPU spinning solution. The Cu / TPU spinning solution was electrospun to form a Cu / TPU fiber membrane on the TPU fiber membrane, resulting in a two-layer composite fiber membrane.
[0050] (3) The two composite fiber membranes were placed in a mixed aqueous solution of 2.5 mol / L NaOH and 0.1 mol / L K2S2O8 for chemical modification. After the reaction was completed, the membranes were washed and dried to obtain hydrophilic and hydrophobic Janus membranes.
[0051] Table 3 Composite schemes and chemical modification time for hydrophilic and hydrophobic Janus membranes
[0052] C0 / C1 Example 4 13.34 0.40 75.60 0、2、4、6 C0 / C2 Example 5 13.34 0.80 75.60 0、2、4、6 C0 / C3 Example 6 13.34 1.20 75.60 0、2、4、6
[0053] Figure 7 This is a graph showing the liquid osmotic pressure across the hydrophilic / hydrophobic Janus membrane under different chemical modification times in Example 5. Figure 7 It was found that hydrophilic and hydrophobic Janus membranes with different chemical modification times were wrapped around the test tubing of a pressure gauge and sealed. Water was then injected into the tubing at a uniform speed using a syringe. The osmotic pressure of the liquid across the hydrophilic and hydrophobic Janus membranes was tested. To facilitate differentiation of the two sides of the membrane during the experiment, DMU (Double membrane upside) was defined as representing the hydrophobic TPU fiber membrane side, and DMD (Double membrane downside) as representing the hydrophilic fiber membrane side. The results are shown in […]. Figure 7 As shown in Table 1, liquid osmotic pressure tests were conducted on different membranes. The results showed that, due to their asymmetric wettability, the liquid osmotic pressure on the hydrophobic side of the hydrophilic Janus membrane showed a significant decreasing trend with increasing chemical modification time (increased hydrophilicity of the hydrophilic fiber membrane), and was lower than that on the hydrophilic side. The largest difference in osmotic pressure between the two sides was observed after 4 hours of chemical treatment, with a difference of 1 kPa.
[0054] Table 3. Liquid osmotic pressure across the C0 / C2 composite porous membrane at different chemical modification times.
[0055]
[0056]
[0057] As shown in Table 3, the osmotic pressure on the DMU side is 7.00 kPa at 0h, 4.25 kPa at 2h, 2.50 kPa at 4h, and 2.50 kPa at 6h; the osmotic pressure on the DMD side is 6.50 kPa at 0h, 3.50 kPa at 2h, 3.50 kPa at 4h, and 3.00 kPa at 6h.
[0058] Figure 8 The air permeability of the hydrophilic-phobic Janus membrane (chemically treated for 6 hours) under different air fluxes in Example 5: (a) 0.05 kg / cm 3 Gas flux; (b) 0.1 kg / cm 3 Gas flux. The test method is as follows: First, hydrophilic and hydrophobic Janus membranes were fixed to the bottom of the long and short tubes of the gas permeation device, respectively. Then, methylene blue stained aqueous solution was injected into the tubes at heights of 10 cm and 20 cm, respectively, and 0.05 kg / cm³ of gas flux was introduced. 3 and 0.1kg / cm 3 The stable gas flow rate was observed. It can be seen that the bubbles inside the tube rise continuously and uniformly, indicating that the hydrophilic-phobic Janus membrane possesses good gas permeability.
[0059] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A hydrophilic fiber membrane, characterized in that: The composite porous membrane consists of TPU fibers, which are in an expanded state and contain hydrophilic Cu(OH)2. The method for preparing the hydrophilic fiber membrane includes the following steps: (1) TPU and cleaned copper nanoparticles were stirred and dispersed in N,N-dimethylformamide to obtain Cu / TPU spinning solution; the Cu / TPU spinning solution was electrospun to obtain Cu / TPU fiber membrane; (2) The Cu / TPU fiber membrane was placed in a mixed aqueous solution of NaOH and K2S2O8 for reaction. After the reaction was completed, it was washed and dried to obtain a hydrophilic fiber membrane.
2. The hydrophilic fiber membrane according to claim 1, characterized in that, In step (1), the Cu / TPU spinning solution includes 0.4-1.2g of copper nanoparticles, 75.6g of N,N-dimethylformamide and 13.34g of TPU.
3. The hydrophilic fiber membrane according to claim 1, characterized in that, The particle size of the copper nanoparticles is 50 nm-100 nm.
4. The hydrophilic fiber membrane according to claim 1, characterized in that, In step (2), the concentration of NaOH in the mixed aqueous solution is 2.5 mol / L and the concentration of K2S2O8 is 0.1 mol / L; the reaction time is 2-6 hours.
5. The hydrophilic fiber membrane according to claim 1, characterized in that, In step (1), the copper nanoparticles are cleaned as follows: the copper nanoparticles are immersed in acetone for ultrasonic cleaning, then immersed in deionized water for ultrasonic cleaning to remove surface dirt, and finally dried.
6. A hydrophilic-hydrophobic Janus membrane, characterized in that, The membrane includes a hydrophobic TPU fiber membrane, on which a hydrophilic fiber membrane is deposited. The hydrophilic fiber membrane is a composite porous membrane composed of TPU fibers, wherein the TPU fibers are in an expanded state and contain hydrophilic Cu(OH)2. The method for preparing the hydrophilic-hydrophobic Janus membrane includes the following steps: 1) TPU is added to N,N-dimethylformamide to obtain a TPU spinning solution; the TPU spinning solution is electrospun to obtain a TPU fiber film; 2) TPU and cleaned copper nanoparticles were stirred and dispersed in N,N-dimethylformamide to obtain Cu / TPU spinning solution; the Cu / TPU spinning solution was electrospun to form Cu / TPU fiber membrane on TPU fiber membrane, thus obtaining two-layer composite fiber membrane; 3) The two composite fiber membranes were placed in a mixed aqueous solution of NaOH and K2S2O8 for reaction. After the reaction was completed, the membranes were washed and dried to obtain a hydrophilic and hydrophobic Janus membrane.