Biomimetics
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2022
·Vol. 7
·期 4
·217
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IF 3.743
Jie Li,Yushan Li,Yiyi Lu,Wentian Shi,Huafeng Tian
With industry development, the separation of oily wastewater is becoming more critical. Inspired by organisms such as lotus leaves, biomimetic superhydrophobic surfaces with micro-nano structures have shown great potential in this regard. In this work, PDMS/PVDF oil–water separation membranes with designed microstructures were prepared by electrospinning technology. The membrane-forming effect of electrospinning with different ratios of PDMS and PVDF was studied. The study found that membranes with high PDMS content were more likely to form microspheres, and PDMS tended to concentrate on the microspheres. The results also showed that the microspheres would bring better hydrophobicity to the membrane. When the ratio of PDMS to PVDF is 1:2, the membrane has a water contact angle of up to 150° and an oil contact angle of 0°. At this ratio, the separation efficiency of the membrane for the water-in-oil emulsion is 98.7%, and it can still maintain more than 98% after ten separation cycles, which is a good candidate for oil–water separation. Furthermore, microspheres enable the membrane to achieve macroscopic uniformity and microscopic phase separation so that the membranes have both good elongation and fracture strength. In addition, the PDMS/PVDF membranes also exhibit excellent UV resistance, and their UV protection factor is greater than 185, making them a potential UV protective material.Keywords:electrospinning;polydimethylsiloxane;polyvinylidene difluoride;oil–water separation;UV protection
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Materials Today Communications
·
2022
·
IF 3.662
Ruitian Bo,Jihua Wang,Chunfeng Wang,Yongliang Wang,Peigang He,Zhidong Han
The selective distribution of inorganic particles in polymer blends is of great significance in designing the composites with excellent properties such as dielectric properties . Molecular dynamics (MD) was applied in this paper to simulate the distribution of BaTiO 3 (BT) and graphene nanoplatelets (GNP) in polystyrene/polyvinylidene fluoride (PS/PVDF) blends. The models of PS and PVDF were built and the phase structure of the blends was simulated at the different PS/PVDF mass ratios. According to the results of solubility parameter and Flory-Huggins interaction parameter (χ), the immiscibility between PS and PVDF was illustrated and the phase transition phenomena were predicted. Combined with the SEM observations, the co-continuous structure of the blend at the PS/PVDF ratio of 6/4 was obtained at the maximal χ value. The binding energy and radial distribution function were calculated to predict the selective distribution of BT or GNP in PS/PVDF blends. According to the results of the MD simulations, the distribution of BT in the PVDF phase and GNP in the PS phase were successfully predicted, which were in good agreement with the experimental results by SEM observations and EDS element mapping. The MD simulations would be effective in building the co-continuous immiscible blends and predicting the selective distribution of functional fillers, which will be helpful for the investigation of functional composites with high performance.
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CARBOHYDRATE POLYMERS
·
2024
·
IF 10.7
Kang Yang,Chao Duan,Zixuan Meng,Yuanmei Liu,Yueyin Liu,Zengyin Xie,Yonghao Ni
Water collection from atmospheric fog was deemed to be an efficient and sustainable strategy to defuse the freshwater scarcity crisis. Fog harvesting and trapping fibers, therefore, has aroused extensive interest due to their ease of preparation, weave, and use. However, the traditional fibers used in fog collector usually have a low fog collection capacity and efficiency because of their unreasonable morphology and structure design. Herein, we proposed a simple process to construct advanced fibers using a one-step wet spinning of hydrophobic polyvinylidene fluoride (PVDF) and hydrophilic cellulose mixture fiber for fog harvesting. The as-prepared fibers featured a petaloid structure and surface hydrophobic gradient, thus facilitating fog deposition, water droplet formation, and drainage. The unique longitudinal groove structure above enabled the hybrid fiber to achieve an excellent fog collection efficiency of 2750.26 mg/cm 2 /h per monofilament , which outstripped most of other fiber materials. When woven these fibers were in a longitudinal array network with an interval of 1 mm, and the fog collection efficiency can maintain at 10.30 L/m 2 /h. Therefore, this work provided a new strategy for further exploration of effective fog collection by cellulose-based fiber materials.
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Membranes
·
2024
·Vol. 14
·期 11
·241
·
IF 3.3
Wenbin Sun,Longbo Xia,Ping Luo,Dong Zou
Polyvinylidene fluoride (PVDF) membranes are extensively utilized in membrane distillation (MD) for water treatment. However, traditional methods easily form asymmetrical membranes with dense skin layers that are detrimental to membrane flux. Herein, an eco-friendly PVDF membrane was fabricated by utilizing a delayed phase separation process without using any pore-forming agents. In addition, methyl-5-(dimethylamino)-2-methyl-5-oxopentanoate (PolarClean) was used as a green solvent without posing risks to humans and the environment. It was demonstrated that the PVDF concentration is crucial in influencing the microstructures and performance of the resulting membranes. As the PVDF concentration increased, the morphology changed significantly, resulting in a reduction of pore size. When feeding the device with NaCl solution at a concentration of 35 g/L, the MD water vapor flux reached 18.49 kg·m −2 ·h −1 , while maintaining a salt rejection of over 99.97% during the continuous operation for 24 h. This work presented a method for producing green PVDF membranes via delayed phase inversion with satisfactory water vapor flux and salt rejection, highlighting their prospect for effective applications in MD for water treatment.
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DESALINATION
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2017
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IF 5.527
Heiyan Zhang,Bingbing Li,De Sun,Xiaoling Miao,Yunlei Gu
In this study, hydrophobic asymmetric SiO 2 -PDMS-PVDF hollow fiber membranes were prepared for the vacuum membrane distillation (VMD). To make PVDF dope solution, hydrophobic nano-fumed silica (SiO 2 ) and polydimethylsiloxane (PDMS) were used. The effects of SiO 2 concentration on membrane parameters such as membrane morphology, hydrophobicity , porosity, thickness, pore size, liquid entry pressure , burst pressure, Fourier transformed infrared spectroscopy , thermal property, mechanical property and permeability were investigated. With the increasing of nano-particle concentration, membrane hydrophobicity, mechanical property and thermal stability improved. Furthermore, membrane VMD properties under various operation conditions were studied, the membranes showed a stable substantial flux of 44.27 LMH and a stable high salt rejection of over 99.9% under the optimum operation conditions of 75 °C, 35 g/L, 87 kPa, and 50 L/h. The results of our research demonstrated that the prepared hydrophobic asymmetric SiO 2 -PDMS-PVDF hollow fiber membranes not only had high permeability and good anti-wetting property but also exhibited a satisfying stability for the vacuum membrane distillation of desalination .
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JOURNAL OF MEMBRANE SCIENCE
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2014
·
IF 4.908
Yanhui Xiang,Fu Liu,Lixin Xue
Under seawater superoleophobic polyvinylidene fluoride (PVDF) membrane inspired by mussel is successfully fabricated for both surfactant-free and surfactant-stabilized oil/seawater separation. The conventional PVDF membrane is modified by a simple solution-immersion method, which was immersed in dopamine aqueous solution for 24 h. The morphology and chemistry of dopamine inspired PVDF membrane was characterized by scanning electron microscope (SEM), atomic force microscopy (AFM), attenuated total reflectance Fourier transform infrared spectra (FTIR-ATR) and X-ray photoelectron spectroscopy (XPS) respectively. The as-prepared membrane obtained stable superoleophobicity under seawater with an oil contact angle of 152±0.3° and extremely low oil-adhesion. Separation experiments for both surfactant-free and surfactant-stabilized emulsions showed that our membrane exhibited high oil/seawater separation efficiency (oil concentration in filtrate below 80 ppm) and substantially high permeability, which are several times higher than that current traditional filtration membrane. Fouling resistance to proteins was also investigated for long-term use purpose. This study provides a facile solution-immersion method to fabricate under seawater superoleophobic membrane, highlighting its great potential in practical oil/seawater separation.
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SEPARATION AND PURIFICATION TECHNOLOGY
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2015
·
IF 3.091
Daqing Tong,Xiaozu Wang,Mohammad Ali,Christopher Q. Lan,Yong Wang,Enrico Drioli,Zhaohui Wang,Zhaoliang Cui
Hydrophobic membrane is desired to avoid pore wetting phenomenon in membrane distillation (MD). In the present paper, highly hydrophobic Hyflon AD60/PVDF composite hollow fiber membranes were prepared by coating a copolymer (Hyflon AD60) of tetrafluoroethylene (TFE) and 2,2,4-trifluoro-5-trifluoromethoxy-1,3-dioxole (TTD) on poly(vinylidene fluoride) (PVDF) membranes. The effects of Hyflon AD60 concentration, coating time, heat-treatment temperature and heat-treatment time on the structures and performances of Hyflon AD60/PVDF composite hollow fiber membranes in vacuum membrane distillation (VMD) process were investigated. The results show that the hydrophobicity of PVDF hollow fiber membrane was significantly improved by coating Hyflon AD60. The optimized Hyflon AD60 concentration, coating time, heat-treatment temperature and heat-treatment time were 0.1 wt%, 10–20 min, 40–50 °C and 9 h, respectively. Employing NaCl solution with concentration of 35 g × L −1 , under a vacuum of 0.09 MPa and feed temperature of 70 °C, the water flux and salt rejection of the composite hollow fiber membrane in VMD process reached to approximately 10 kg × m −2 × h −1 and higher than 99.9 %, respectively, and kept stable, indicating that Hyflon AD60/PVDF composite membrane is an excellent candidate for operation in VMD operation.
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RSC Advances
·
2015
·Vol. 5
·期 84
·68998-69005
·
IF 3.84
Yongliang Chen,Xinzhen Zhao,Chunju He
Polydimethylsiloxane-graft-polyethylene glycol (PDMS-graft-PEG), an amphiphilic polymer with four hydrophilic arms, was prepared and used to improve the antifouling property of PVDF membranes by a dip-coating method. The interface properties of the modified PVDF membranes were investigated and it was found that the increased molecular weight of the PEG segment exhibited a negative effect on the anchoring ability of the PDMS-graft-PEG on the membrane surface. However, the antifouling properties of the modified membranes were significantly improved due to the dual-mode antifouling ability of fouling repulsion (PEG) and fouling release (PDMS). The adsorption mass of BSA on the modified membrane surface decreased to a low level, and an enhanced water flux recovery ratio after washing (FRR-W) of the modified membranes was obtained for two typical pollutants of bovine serum albumin and sodium alginate. It was demonstrated that surface anchoring is an effective way to improve the interface characteristics of membrane materials with functional polymers.
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Journal of Energy Storage
·
2024
·
IF 8.9
Tao Wang,Yuqun Deng,Huajun Sun,Dawei Wang,Mingfu Zhang
Commercially available flexible dielectric capacitors with high energy density ( U d ) still present a significant challenge due to the inherent trade-off between breakdown strength ( E b ) and dielectric constant ( ε r ). In this context, a novel strategy is proposed to synchronously improve the E b and ε r of PVDF-based polymer capacitors by incorporating AZO-BT heterostructure nanoparticles, forming AZO-BT/PVDF composite films. Initially, the tightly polarized AZO affixed to the surface of BT particles create a localized electric field that enhances and sustains the polarization intensity of BT. Additionally, the heterojunction electric field generated inhibits the migration of the injected electron. Furthermore, the semiconducting AZO with high electron affinity effectively captures and traps the injected and excited electrons . Notably, the existed oxygen vacancies in AZO significantly enhances E b and polarization reverse. Consequently, the AZO-BT/PVDF composite film achieves the highest U d of 9.10 J·cm −3 at 460 MV·m −1 . The innovative approach of constructing a semiconducting-ferroelectric heterostructure offers a promising avenue for designing and fabricating high energy density polymer capacitors.
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ACS Applied Polymer Materials
·
2024
·
IF 4.4
Jingyu Du,Yu Xue,Yuhuan Xu,Xiao Zhan,Daohai Zhang
We have successfully developed a PVDF/EAA [poly(vinylidene fluoride)/poly(ethylene acrylic acid)]-piperazine (PIP) composite nanofiltration membrane for dye isolation. In this paper, we conduct interfacial polymerization (IP) on PVDF/EAA composite membranes to generate a separation layer that aims at enhancement of the permeation flux of nanofiltration membranes. Subsequently, Fourier transform infrared spectroscopy (FTIR), contact angle, X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) were used to characterize the performance of the prepared samples. In addition, under the different concentrations of the PIP aqueous layer, an intensive study was resorted to gauge the effects of homotrimethylene tricarbonyl chloride (TMC) concentration and reaction time on the characteristics of nanofiltration membranes. Under the optimized situation, the pure water flux could reach 76.84 L/(m2 h) and the retention of bovine serum albumin (BSA), Congo red, and methylene blue could reach 96.34%, 97.93%, and 96.83%, respectively. Substantially, the nanofiltration membrane has good potential to be applied in dye wastewater treatment.
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JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2024
·Vol. 35
·期 16
·1-12
·
IF 2.8
Xia Enjie,Zhang Hong,Tang Zhiruo,Xu Yilin,Wu Yanmei,Li Zhicheng
Solid polymer electrolytes (SPEs) with high ionic conductivity and electrochemical stability are crucial for the potential practical applications of solid-state lithium metal batteries. In SPEs based on polyvinylidene fluoride (PVDF), the addition of N , N -dimethylformamide (DMF) enhances ionic conductivity but reduces the electrochemical stable window. This work proposes a strategy to improve the stability of PVDF-based SPEs with high ionic conductivities using LiNO 3 additive. By adding 5% of LiNO 3 (comparing to the weight of LiTFSI lithium salt), the ionic conductivity of prepared PVDF-based SPEs achieves up to 10 −4 S cm −1 at 30 ℃. The assembled Li|SPE|NCM811 cells with the LiNO 3 -modified SPE film as separator maintained a capacity retention rate of 93.0% after 200 electrochemistry cycles induced at a current density of 0.5 C. The influence of LiNO 3 in the interface resistance, Li-ionic transfer number, solid electrolyte interface phase, and electrochemistry performance of LIBs is investigated.
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Nanoscale Advances
·
2025
·
IF 4.6
Yu Ma,Lan Yang,Shangdi Wu,Liran Xu,Hua Huang
Polydopamine (PDA) is a widely utilized photothermal conversion material recognized for its ease of synthesis and environmental friendliness. However, its relatively weak light absorption capabilities lead to lower photothermal efficiency, restricting its application in solar steam generation (STG) processes. To effectively enhance light absorption, this study introduces a deep co-deposition method for the microstructural design of STG membranes. Unlike traditional surface co-deposition methods, which coat a layer of PDA on the membrane surface, the deep co-deposition method allows for the incorporation of PDA within the internal nanohydrogel structural units of the membrane. This approach significantly increases the PDA loading, resulting in a marked enhancement of light absorption capabilities. In the near-infrared region (800–2500 nm), where the light absorption of PDA is relatively weak, the absorbance improved from 70.18% (surface co-deposition) to 88.20% (deep co-deposition). While PDA has been extensively studied across various fields, its application as a structural and functional additive in hydrogels remains limited, particularly in comparison to the rapid advancements in PDA-based surface-engineered hydrogels. Thus, this study may provide valuable insights for related research areas.
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