A polyvinylidene fluoride-based composite membrane modified by zinc oxide-polydopamine-silver core-shell structure nanoparticles and a preparation technique thereof
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- JILIN JIANZHU UNIVERSITY
- Filing Date
- 2026-04-26
- Publication Date
- 2026-06-30
AI Technical Summary
Existing PVDF membranes are susceptible to fouling in water treatment, leading to decreased permeation flux and shortened service life. Existing modification technologies suffer from problems such as uneven nanoparticle dispersion, weak binding force, and poor antibacterial durability.
By introducing ZnO@PDA-Ag core-shell structured nanoparticles into a PVDF matrix and blending them with PVDF-g-IL, and precisely controlling the reaction conditions to achieve uniform loading of nanoparticles, a PVDF-g-IL/ZnO@PDA-Ag composite film was formed.
It significantly improves the membrane's hydrophilicity, resistance to protein fouling, and antibacterial properties, thereby enhancing the membrane's separation and purification efficiency.
Smart Images
Figure CN122298228A_ABST
Abstract
Description
Technical Field
[0001] A polyvinylidene fluoride composite membrane modified with zinc oxide-polydopamine-silver core-shell structure nanoparticles and its preparation technology belong to the field of water treatment membrane material technology. Background Technology
[0002] Polyvinylidene fluoride (PVDF) has become a commonly used polymer material for preparing microfiltration, ultrafiltration, and nanofiltration membranes due to its excellent mechanical strength, chemical stability, thermal stability, and film-forming properties. It is widely used in water treatment, biomedicine, food industry, and energy. However, the strong hydrophobicity of PVDF itself makes its membranes prone to adsorbing pollutants such as proteins, oil droplets, and microorganisms from the water, leading to membrane fouling. Membrane fouling significantly reduces permeate flux, increases operating energy consumption, and shortens membrane lifespan. Therefore, improving the hydrophilicity and antifouling ability of PVDF membranes is a key technical challenge in this field.
[0003] To improve the hydrophilicity and antifouling properties of PVDF membranes, researchers have developed various modification strategies, including surface grafting of hydrophilic polymers, blending modification to introduce hydrophilic additives, and loading functional nanoparticles on or inside the membrane surface. Among these, blending modification has attracted much attention due to its ease of operation and wide applicability. In recent years, ionic liquids (ILs) have been used for the hydrophilic modification of PVDF membranes due to their excellent solubility, designability, and antibacterial properties. By introducing ionic liquids into the PVDF backbone through electron beam irradiation or chemical grafting, PVDF-g-IL materials are prepared, which not only improve the hydrophilicity of the matrix but also endow the membrane material with certain antibacterial and antifouling capabilities.
[0004] To improve the hydrophilicity and antifouling properties of PVDF membranes, researchers have developed various modification strategies, including surface grafting of hydrophilic polymers, blending modification to introduce hydrophilic additives, and loading functional nanoparticles on or inside the membrane surface. Among these, blending modification has attracted much attention due to its ease of operation and wide applicability. In recent years, ionic liquids (ILs) have been used for the hydrophilic modification of PVDF membranes due to their excellent solubility, designability, and antibacterial properties. By introducing ionic liquids into the PVDF backbone through electron beam irradiation or chemical grafting, PVDF-g-IL materials are prepared, which not only improve the hydrophilicity of the matrix but also endow the membrane material with certain antibacterial and antifouling capabilities.
[0005] Currently, although there are reports of introducing ZnO, Ag, or PDA separately or in combination into PVDF membranes, systematic research on the synergistic enhancement of the hydrophilicity, antifouling, and antibacterial properties of PVDF membranes by simultaneously combining ionic liquid grafting modification with ZnO-PDA-Ag core-shell nanoparticles is still insufficient. Existing techniques often suffer from problems such as uneven nanoparticle dispersion, weak particle-matrix bonding, and poor antibacterial durability during preparation. Therefore, developing a novel composite membrane using ZnO@PDA-Ag core-shell nanoparticles as functional fillers and blending them with a PVDF-g-IL matrix via phase separation technology has significant application value. This technology achieves uniform loading of nanoparticles and controllable construction of membrane structures by precisely controlling the reaction conditions of each step (such as buffer pH, ultrasonic time, irradiation dose, stirring temperature, and coagulation bath composition). The resulting PVDF-g-IL / ZnO@PDA-Ag composite membrane maintains good mechanical properties while significantly improving hydrophilicity, resistance to protein contamination, and antibacterial properties, and is expected to be widely used in drinking water purification, wastewater treatment, and biopharmaceutical separation. Summary of the Invention
[0006] This invention relates to polyvinylidene fluoride composite membranes modified with ZnO@PDA-Ag core-shell structured nanoparticles and their preparation technology. The prepared composite membranes exhibit efficient separation and piezoelectric-photocatalytic purification effects, and can be used to prepare PVDF-based multifunctional water treatment separation membranes with good application prospects.
[0007] This invention utilizes electron beam irradiation-induced free radical grafting to graft 1-butyl-3-vinyl imidazole bromide ionic liquid onto PVDF macromolecular segments, with a PVDF-g-IL piezoelectric matrix as the framework material; simultaneously, ZnO@PDA-Ag composite nanoparticles with a unique core-shell structure are designed and prepared as functional additives.
[0008] The key feature of this invention is that the intermediate PDA layer in the tightly packed ZnO@PDA-Ag composite particle structure enhances the interaction between ZnO and Ag and improves the compatibility of the inorganic filler in the organic matrix. The interaction between the three interfaces effectively increases the transport rate of photogenerated carriers and promotes carrier transfer, thereby significantly improving the photocatalytic activity of ZnO. Furthermore, the grafting of IL endows PVDF with high-voltage electrical properties, enabling it to generate piezoelectric polarization and form an internal electric field under ultrasonic and light irradiation, further improving the electron-hole separation and transfer efficiency within ZnO, resulting in superior pollutant catalytic degradation capabilities.
[0009] The PVDF-g-IL / ZnO@PDA-Ag composite membrane designed in this invention can achieve efficient, simple, multifunctional, and sustainable wastewater purification, providing a potential method for water environment management and solving membrane fouling problems. Attached Figure Description
[0010] Figure 1 The ¹H NMR spectra of the PVDF membrane, PVDF-g-IL membrane, and PVDF-g-IL / ZnO@PDA-Ag membrane are shown.
[0011] Figure 2 XPS spectra of PVDF membrane, PVDF-g-IL membrane, and PVDF-g-IL / ZnO@PDA-Ag membrane.
[0012] Figure 3 XPS spectra of the C1s core level of PVDF membrane, PVDF-g-IL membrane, and PVDF-g-IL / ZnO@PDA-Ag membrane.
[0013] Figure 4 XRD patterns of PVDF membrane, PVDF-g-IL membrane, and PVDF-g-IL / ZnO@PDA-Ag membrane.
[0014] Figure 5 The images show the FTIR spectra of the PVDF membrane, PVDF-g-IL membrane, and PVDF-g-IL / ZnO@PDA-Ag membrane. Detailed Implementation
[0015] 10 g of ZnO nanoparticles were placed in 200 mL / 10 mM Tris-HCl buffer solution (pH=8.5) and sonicated in an ice bath for at least 30 minutes. Then, 1 g of DA-HCl was added to the dispersion and sonicated for another 10 minutes. After that, the mixture was vigorously stirred at room temperature, washed repeatedly by centrifugation with ethanol and deionized water, and thoroughly dried in a vacuum oven at 60°C to obtain gray ZnO@PDA powder. 2 g of BN@PDA nanoparticles were taken and sonicated in 95 mL of deionized water. Then, 0.06 g of AgNO3 was first dissolved in 5 mL of deionized water and then quickly added to the ZnO@PDA suspension. The mixture was stirred and reacted at room temperature. After repeated centrifugation and washing with ethanol and deionized water and drying, brownish-gray ZnO@PDA powder with the chemical formula ZnO@PDA-Ag was finally obtained.
[0016] Completely dried PVDF powder was irradiated with a 30 kGy electron beam at room temperature and in an N2 environment. Next, the irradiated PVDF powder, IL monomer, and pore-forming agent PVP were added to a DMAc solvent. The solution was heated to 60°C under N2 protection and continuously mechanically stirred. Subsequently, ZnO@PDA-Ag particles were uniformly ultrasonically dispersed in another 10 mL of DMAc solvent, and then added to the above solution, with stirring continued for 4 hours. The prepared casting solution was poured onto a glass plate, and a liquid film with a thickness of 0.20 mm was scraped out using a film scraper. After the liquid film was completely solidified in a coagulation bath, it was peeled off from the glass plate.
[0017] Figure 1 The ¹H NMR spectra of the PVDF membrane, PVDF-g-IL membrane, and PVDF-g-IL / ZnO@PDA-Ag membrane are shown below. Figure 1 The 1H-NMR spectrum reveals a distinct characteristic of IL (inductively coupled plasma) compared to the pure PVDF spectrum. Typical proton signal peaks belonging to IL are clearly observed on the PVDF-g-IL curve. These peaks originate from positions e (8.19 ppm), f (7.93 ppm), and g (9.48 ppm) within the imidazole ring of the grafted IL, and from positions a (0.93 ppm), b (1.16 ppm), c (1.81 ppm), and d (4.19 ppm) on the 3-butyl group of the imidazole ring. The appearance of these new peaks directly confirms the successful grafting of IL onto the PVDF matrix film.
[0018] Figure 2 XPS spectra of PVDF film, PVDF-g-IL film, and PVDF-g-IL / ZnO@PDA-Ag film are shown. The pure PVDF film only shows prominent emission peaks corresponding to C 1s (286.1 eV), F 1s (689.1 eV), and O 1s (533.1 eV), while the PVDF-g-IL film shows additional N 1s (399.1 eVZ) peak and Br 3d (64.1 eVZ) peak, which further proves the grafting of IL onto the PVDF chain segment.
[0019] Figure 3 XPS spectra of the C1s core level of the PVDF membrane, PVDF-g-IL membrane, and PVDF-g-IL / ZnO@PDA-Ag membrane are shown. Compared with the pure PVDF membrane, the PVDF-g-IL membrane shows a new peak at 284.5 eV that originates from the IL hydrocarbon framework. Based on the fitted area ratio of the spectra, the molar ratio of [C]IL / [C]PVDF in the PVDF-g-IL membrane is approximately 0.221:1.
[0020] Figure 4The XRD patterns of the PVDF film, PVDF-g-IL film, and PVDF-g-IL / ZnO@PDA-Ag film are shown. The diffraction patterns are at 18.2. ◦ and 19.8 ◦ The XRD patterns show central peaks corresponding to the α and β phases of the PVDF film, respectively. Compared with the pure PVDF film, the PVDF-g-IL film has a relatively higher β phase content and a relatively lower α phase content, indicating that IL grafting is beneficial for inducing the α phase to β phase transfer in PVDF. This also gives the PVDF-g-IL film superior piezoelectric properties. The XRD diffraction pattern also clearly shows diffraction peaks belonging to the hexagonal ZnO phase and the cubic Ag phase. However, compared with the PVDF-g-IL / ZnO film, the intensity of the ZnO diffraction peak in the PVDF-g-IL / ZnO@PDA-Ag film is slightly lower. This is mainly because the PDA-Ag shell covers part of the ZnO signal. The change in diffraction peak intensity also indirectly confirms the core-shell structure of ZnO@PDA-Ag.
[0021] Figure 5 The images show the FTIR spectra of PVDF membrane, PVDF-g-IL membrane, and PVDF-g-IL / ZnO@PDA-Ag membrane. The spectral curves of the PVDF-g-IL membrane and its composite membranes exhibit distinct new characteristic peaks, which originate from the C=N imidazole ring vibration peaks (1550 and 1573 cm⁻¹) of the grafted IL. -1 The peak of the stretching vibration of the CC trunk (1668 cm⁻¹) and the peak of the CC trunk stretching vibration. -1 Compared to pure PVDF membranes, the PVDF-g-IL spectral curves show differences at 760 and 973 cm⁻¹. -1 The characteristic α-phase peaks at 842 and 1276 cm⁻¹ show disappearance or significant attenuation; conversely, at 842 and 1276 cm⁻¹, the characteristic α-phase peaks disappear. -1 The peak intensity of the characteristic β phase at the location increased significantly, which also proves that IL grafting can induce the transformation of the crystalline phase of PVDF from nonpolar α crystal to polar β crystal.
Claims
1. A polyvinylidene fluoride composite membrane modified with zinc oxide-polydopamine-silver core-shell structure nanoparticles and its preparation technology, characterized in that the composite membrane is formed by incorporating zinc oxide-polydopamine-silver as functional composite particles into a polyvinylidene fluoride grafted ionic liquid matrix through phase separation technology, and its chemical formula is PVDF-g-IL / ZnO@PDA-Ag.
2. The polyvinylidene fluoride composite film modified with zinc oxide-polydopamine-silver core-shell structured nanoparticles and its preparation technology according to claim 1, characterized in that... The composite membrane is prepared according to the following steps: Step 1: Place 10 g of ZnO nanoparticles in 200 mL / 10 mM Tris-HCl buffer solution (pH=8.5) and sonicate for at least 30 minutes in an ice bath. Then add 1 g of DA-HCl to the dispersion and sonicate for another 10 minutes. After that, stir the mixture vigorously at room temperature, wash it repeatedly with ethanol and deionized water by centrifugation, and dry it thoroughly in a vacuum oven at 60°C to obtain gray zinc oxide-polydopamine powder. Take 2 g of BN@PDA nanoparticles and sonicate them in 95 mL of deionized water. Then dissolve 0.06 g of AgNO3 in 5 mL of deionized water and quickly add it to the zinc oxide-polydopamine suspension. Stir and react at room temperature. After washing and drying repeatedly with ethanol and deionized water by centrifugation, a brownish-gray zinc oxide-polydopamine-silver powder with the chemical formula ZnO@PDA-Ag is finally obtained. Step 2: Irradiate the completely dried polyvinylidene fluoride (PVDF) powder using a 30 kGy electron beam at room temperature and in an N2 environment; then, add the irradiated PVDF powder, IL monomer, and pore-forming agent PVP to a DMAc solvent, and heat the solution to 60°C under N2 protection while continuously stirring mechanically; subsequently, uniformly ultrasonically disperse ZnO@PDA-Ag particles in another 10 mL of DMAc solvent, and then add them to the above solution and continue stirring for 4 hours. The chemical formula is PVDF-g-IL / ZnO@PDA-Ag. Step 3: Pour the prepared casting solution onto a glass plate and use a film scraper to scrape out a liquid film with a thickness of 0.20 mm. After the liquid film has completely solidified in the coagulation bath, peel it off from the glass plate.
3. In the method for preparing polyvinylidene fluoride composite membrane modified with zinc oxide-polydopamine-silver core-shell structured nanoparticles according to claim 2, in step one, the time for vigorous stirring of the mixed solution at room temperature after ultrasonication is 24 hours.
4. In the method for preparing a polyvinylidene fluoride composite membrane modified with zinc oxide-polydopamine-silver composite particles according to claim 2, in step one, deionized water containing AgNO3 is added to the ZnO@PDA suspension and stirred rapidly, and the reaction is carried out at room temperature for 1 hour.
5. In the preparation method of a zinc oxide-polydopamine-silver composite particle modified polyvinylidene fluoride composite film according to claim 2, in step two, the irradiated PVDF powder, IL monomer and pore-forming agent PVP are added to DMAc solvent, and the mixed solution is reacted continuously for no less than 6 hours under N2 and 60°C reaction conditions.
6. In the method for preparing polyvinylidene fluoride composite membrane modified with zinc oxide-polydopamine-silver core-shell structure nanoparticles according to claim 2, in step three, the liquid membrane is completely solidified into a film in a coagulation bath, and the coagulation bath should be deionized water.