PVDF Powder Research Articles

Molecularly imprinted composite membranes with the dual imprinted network for highly selective separation of acteoside

Acteoside (ACT) is the main active ingredient in phenylethanoid glycosides (PhGs) and it has anti-inflammatory, liver-protecting, and memory-enhancing functions. It remained a challenge to develop an imprinted membrane with high permselectivity for separation of ACT from PhGs. In this paper, ACT was used as a template molecule to design dual imprinted molecularly imprinted composite membranes (DIMICMs). The dual imprinted network structure was constructed and played a vital role in DIMICMs. On one hand, ACT imprinted network was formed on the surface of ACT-KH570/PDA/CMK-3@PVDF, and it can recognize and adsorb ACT. On the other hand, the imprinted filler ACT-KH570/PDA/CMK-3 was mixed with PVDF powder to construct the ACT imprinted network in the membrane, and the imprinted network can further recognize and accommodate the ACT. The dual imprinted network acted synergistically for dual recognition of ACT. The result showed that the DIMICMs had the high permselectivity (β = 14.61), selectivity (α = 4.64) and rebinding capacity (105.58 mg/g). The designed approach of DIMICM with a dual imprinted network provided a strategy for the separation of natural products.

Fabrication of PVDF membranes via VIPS-NIPS technique for water desalination: Effect of preparation condition

The operating cost of the desalination process can be decreased by using the membrane distillation (MD) process due to very low operating pressure and mild operating temperature. Attempts to find the proper membrane for application in MD attract the attention of many researchers. In this paper, PVDF powder was employed for assembling membranes via the VIPS method for operating in air-gap membrane distillation (AGMD). The influence of the ethanol concentration in the coagulation bath and VIPS time was studied. PVDF membrane characteristics were analyzed via pore size distribution, volumetric porosity, thickness, scanning electron microscope (SEM), measuring water contact angle, water flux, and salt rejection. A nodular structure was found for the membranes resulting from delayed demixing and solid-liquid phase separation. Moreover, the results indicated a larger membrane pore size was formed and the hydrophobicity was improved. The hydrophobicity and pore size are two important factors for membrane distillation that can affect and enhance membrane permeability. Moreover, studying the influence of nanoparticles showed that SiO2 nanoparticles are more effective than TiO2. The highest water contact angle was obtained when SiO2 nanoparticles were sprayed on the surface resulting in higher permeability and salt rejection in AGMD. The AGMD experiments' results showed that the membrane permeability increased from 0.3 to 2.41 L/m2.h, and salt rejection over 99.5 % was obtained.

Preparation of PVDF/PVA composite films with micropatterned structures on light-cured 3D printed molds for hydrophilic modification of PVDF

Abstract Polyvinylidene fluoride (PVDF) is widely used in biotechnology due to its excellent biocompatibility, high temperature and pressure resistance, and outstanding mechanical properties. However, the hydrophobic nature of PVDF surface hinders the attachment of biological proteins. In order to enhance the wettability of PVDF surfaces, this study prepared composite films by blending PVDF with polyvinyl alcohol (PVA), and micro-patterned structures were fabricated on the material surface using a mold-replication method based on digital light processing (DLP) photopolymerization printing technology. A series of characterization techniques including surface morphology analysis, chemical composition analysis, and wettability testing were employed. The surface morphology analysis results indicated that the method of using DLP photopolymerization technology to print mold replicas and create micro-patterned structures was indeed effective in creating micro-patterned structures on both PVDF and PVDF/PVA composite films. The chemical composition analysis showed that the spin-coating of PVDF powder material resulted in PVDF β-phase crystalline structure, which has a positive effect on cell growth. Furthermore, the introduction of hydrophilic groups was achieved by mixing PVDF with PVA. Wetting test results indicate that the incorporation of the hydrophilic material PVA and micro-patterned surfaces both contribute to the improved hydrophilicity of the material. The water contact angle of the micro-patterned PVDF/PVA composite film reached 30.8°, exhibiting excellent hydrophilic properties. This study achieved the optimization of PVDF surface properties through micro-patterned surface modification and material composition design, providing novel insights for the further development of PVDF materials in the field of biotechnology.

Rapid preparation of PET-PVDF Janus fiber felt for emulsion separation

Frequent oil spills and an increase in industrial wastewater are global environmental issues, causing a waste of oil resources and even threatening the safety of marine creatures and humans. However, the manufacturing process of most Janus materials is very complex. Herein, we develop a simple, fast, and efficient emulsion separation material, and a Janus fiber felt (J-PPF4) with switching emulsion separation was successfully fabricated by facile blending PVDF powder with PET, heat treatment, and single side modification method. The entire preparation process takes approximately 60 min, while the hydrophilic modification time is only 10 s. The obtained J-PPF4 with asymmetric wettability exhibited excellent separation efficiency (99.4 % for water-in-oil emulsion, 96.3 % for oil-in-water emulsion) as well as admirable flux (1749.17 L m-2h−1 for water-in-oil and 622.39 L m-2h−1 for oil-in-water). Furthermore, the J-PPF4 still possessed superior stability in harsh environments, and the separation efficiency had no dramatic fluctuation after 10 separation cycles, indicating the fabulous separation recyclability of the J-PPF4. The simple and rapid preparation process and exceptional separation performance of the J-PPF4 will provide more enlightenment for the design and preparation of Janus separation materials for potential industrial applications.

Fabrication of hydrophobic bi-layer fiber-aligned PVDF/PVDF-PSF membranes using green solvent for membrane distillation

Green high-flux poly(vinylidene fluoride) (PVDF) membranes with hydrophobic properties are beneficial for membrane distillation (MD). In this study, PVDF and polysulfone (PSF) polymer powders were dissolved in PolarClean to form immiscible polymer solutions. After casting the PVDF-PSF membranes and inducing a phase inversion procedure in water, a high-porosity fiber aligned PVDF-PSF membrane was obtained. The PVDF-PSF membranes also exhibited high tensile strength and satisfactory vapor flux. However, the surface hydrophobic properties were relatively poor and the surface pore sizes were large. Therefore, a PVDF/PolarClean/propylene glycol (PG) solution was used to construct rough PVDF nanoparticles (NPs) on the PVDF-PSF membrane surface. The PVDF NPs decreased the membrane pore size and increased the surface roughness. The resulting membrane exhibited a highly hydrophobic membrane surface and a higher liquid entry pressure than the pristine PVDF-PSF membrane. In addition, the whole process did not contain any toxic solvents and the stability of the PVDF/PVDF-PSF membrane was satisfactory after ultrasonic treatment. In the desalination of saline water containing 3.5 wt% and 12 wt% NaCl solutions, the resulting membrane showed a high water flux, with a rejection rate higher than 99.99 % after 120 h. This study provides important guidance for polymer membranes for MD.

Chemical cleaning and membrane aging of poly(vinylidene fluoride) (PVDF) membranes fabricated via non-solvent induced phase separation (NIPS) and thermally induced phase separation (TIPS)

Poly(vinylidene fluoride) (PVDF) is one of the most used membrane materials in the water industries, and the PVDF membrane can be fabricated majorly through non-solvent induced phase separation (NIPS) and thermally induced phase separation (TIPS). The differences in membrane aging of NIPS-PVDF and TIPS-PVDF remain unclear. In this study, the agings of commercially available NIPS-PVDF and TIPS-PVDF membranes were investigated in the pilot-scale MBRs experiment as well as in the batch soaking tests. The raw PVDF powders in different crystalline polymorphs were also subjected to aging tests to examine the relation between PVDF polymorphous structure and aging. The results showed that the NIPS-PVDF membrane experienced more severe aging in the pilot-scale MBR experiment in comparison with the TIPS-PVDF membrane. Acid aging dislodged and eliminated the additives in the membrane, but did not attack the PVDF. NIPS-PVDF membrane was the dominant β PVDF phase, which was more susceptible to dehydrochlorination in alkaline oxide aging. The thin top layer in the asymmetric structure of the NIPS-PVDF membrane resulted in its vulnerability against alkaline oxide aging. The α PVDF phase and the symmetric structure of the TIPS-PVDF membrane contributed to its greater stability in alkaline oxide aging. Overall, the results can provide a basis for selecting a chemical cleaning strategy for PVDF membranes, and for improving the anti-aging characteristics of the PVDF in the membrane fabrication.

Extensional Rheology of Poly(vinylidene fluoride)/N,N-dimethylformamide Solutions

Typical extension flow occurs in electrospinning process of Poly(vinylidene fluoride) (PVDF) solutions such that researchers focus on extensional rheological behaviors of PVDF solutions. The extensional viscosity of PVDF solutions is measured to know the fluidic deformation in extension flows. The solutions are prepared by dissolving PVDF powder into N,N-dimethylformamide (DMF) solvent. A homemade extensional viscometric device is used to produce uniaxial extension flows and the feasibility of the viscometric device is verified by applying the glycerol as a test fluid. Experimental results show that PVDF/DMF solutions are extension shinning as well as shear shinning. The Trouton ratio of thinning PVDF/DMF solution is close to three at very low strain rate and then reaches a peak value until it drops to a small value at high strain rate. Furthermore, an exponential model may be used to fit the measured values of uniaxial extensional viscosity at various extension rates, while traditional power-law model is applicable to steady shear viscosity. For 10~14% PVDF/DMF solution, the zero-extension viscosity by fitting reaches 31.88~157.53 Pa·s and the peak Trouton ratio is 4.17~5.16 at applied extension rate of less than 34 s-1. Characteristic relaxation time is λ~100 ms and corresponding critical extension rate is ε˙c~5 s-1. The extensional viscosity of very dilute PVDF/DMF solution at very high extension rate is beyond the limit of our homemade extensional viscometric device. This case needs a higher sensitive tensile gauge and a higher-accelerated motion mechanism for test.

Reinforcement of binder adhesion for nickel-rich layered oxide in lithium-ion batteries using perfluorinated molecular surface modification

Ni-rich layered oxides are considered the most promising candidates for cathode materials for use in electric vehicles because of their high energy density and low cost. However, the cyclability of Ni-rich layered oxide needs to be improved because it suffers from contact loss by microcracks owing to the large anisotropic volume changes during cycling. Furthermore, its unstable surface, which releases lithium impurities by water contamination, must also be mitigated. To improve the adhesive force with a polyvinyl fluoride (PVdF) binder as well as the air-stability, a self-assembled monolayer of 1H,1H–2H,2H-perfluorodecyltriethoxysilane (PFDTES) is introduced onto the surface of Ni-rich layered oxide cathode powder. A molecular functional monolayer with fluorocarbons on Ni-rich layered oxide powder is delivered to achieve an ∼ 13 Å thin homogeneous molecular-level functional coating at a negligible weight ratio. The functionalized surface improves the adhesion between PVdF and cathode powder by F⋯F interaction, relieving the electrode detachment. As a result, cycling failure mode is remarkably mitigated. The fluorinated hydrophobic surface alleviates water contamination, thereby reducing lithium impurities.

Alkali-Grafting Proton Exchange Membranes Based on Co-Grafting of α-Methylstyrene and Acrylonitrile into PVDF.

A novel alkali-induced grafting polymerization was designed to synthesize a PFGPA proton exchange membrane based on the co-grafting of α-methyl styrene (AMS) and acrylonitrile (AN) into the poly(vinylidenedifluoride) (PVDF) membrane. Three kinds of alkali treatments were used: by immersing the PVDF membranes into a 1 M NaOH solution and mixing the PVDF powders with 16% or 20% Na4SiO4. Then, AMS with AN could be co-grafted into the PVDF backbones in two grafting solvents, THF or IPA/water. Finally, the grafted membranes were sulfonated to provide the PFGPA membranes. In the experiments, the Na4SiO4 treatments showed a greater grafting degree than the NaOH treatment. The grafting degree increased with the increasing amount of Na4SiO4. The grafting solvent also influenced the grafting degree. A 40–50 percent grafting degree was obtained in either the THF or IPA/water solvent after the Na4SiO4 treatment and the THF resulted in a greater grafting degree. FTIR and XPS testified that the PFGPA membranes had been prepared and a partial hydrolysis of the cyano group from AN occurred. The PFGPA membranes with the grafting degree of about 40–50 percent showed a better dimensional stability in methanol, greater water uptake capabilities, and lower ion exchange capacities and conductivities than the Nafion 117 membranes. The PFGPA membrane with the 16% Na4SiO4 treatment and THF as the grafting solvent exhibited a better chemical stability. The obtained experimental results will provide a guide for the synthesis of alkali-grafted PFGPA membranes in practical use.

Study on preparation process and enhanced piezoelectric performance of pine-needle-like ZnO@PVDF composite nanofibers

The effect of hydrothermal process on the morphology and piezoelectric performance of zinc oxide/polyvinylidene fluoride (ZnO@PVDF) composite nanofibers is rarely studied. In this work, highly aligned ZnO nanorods were epitaxially grown on the electrospun PVDF nanofibers to form ZnO@PVDF composite nanofibers with a pine-needle-like bionic structure. Nanofibers before and after hydrothermal reaction were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and piezoelectric analysis. Results demonstrated that hydrothermal reaction conditions, including mass ratio of ZnCl2 to HMTA, ammonium hydroxide volume, hydrothermal reaction time and temperature should be carefully controlled and cooperated with each other to produce ZnO nanorods with ideal microstructure and piezoelectric performance. FTIR and XRD results confirmed the transformation of β phase in PVDF nanofibers from α phase in PVDF powder due to the elongation under strong electric field during electrospinning. Results of SEM and XRD certified the successful growth of ZnO nanorods with hexagonal wurtzite structure, which plays an important role in facilitating the percentage of β phase and the resulted piezoelectric capacity of ZnO@PVDF composite nanofibers. All of these characterizations suggest that the proposed pine-needle-like ZnO@PVDF composite nanofibers demonstrate promising potential in the wide application of electromechanical energy conversion.

Freestanding 3D piezoelectric PVDF sensors via electroprinting

Polyvinylidene fluoride, PVDF is a soft piezoelectric material with potential applications in robotic sensors and actuators, wearable electronics, and energy harvesting. The sensitivity of piezoelectric PVDF is attributed primarily to the β-crystalline phase with oriented dipoles. 3D electroprinting process is a promising technique to achieve 3D PVDF-based piezoelectric devices because the combined mechanical stretching and electric field-assisted poling can improve the electroactive crystalline phases in PVDF. In this work, we show that the incorporation of an anti-solvent in the PVDF solution was instrumental in obtaining an optimum solution viscosity and solvent evaporation rate to achieve mechanically stable layer-by-layer printing. Two major process parameters further influencing the resolution of the printed structure were nozzle-to-collector distance and extrusion pressure. Freestanding 3D PVDF structures with an average individual layer height as small as 30 µm and continuous prints for multiple 3D designs have been achieved. FTIR and XRD spectra show an improvement in the electroactive β and γ phases in the electroprinted PVDF compared to the dominant α phase of PVDF powder. Furthermore, the 3D PVDF structures display sensitivity to various load profiles at varying frequencies with the piezoelectric voltage coefficient (g33) range between 1.72E-4 and 4.08E-4 V.m/N.

Morphological Study of Fabricated PVDF Based Hydrophobic Membrane for Different Additives and Coagulation Bath Temperature

The demand of membrane distillation (MD) has increased since last few decades for numerous applications. The membrane used in MD is hydrophobic; therefore, the focus has been emphasised on the development of a suitable membrane with desired microstructure. In this study, the flat sheet hydrophobic membrane of suitable properties has been casted with various additives such as water, ethane-di-ol, and propan-2-ol in dope solution using a non-solvent induced phase separation (NIPS) technique. The effect of water content in dope solution has been studied on casted membrane porosity and contact angle. The maximum contact angle and porosity were found to be 96° and 53.23% at 4 weight percent of water content in dope solution of PVDF polymer and di.methyl.acetamide as solvent. It was found that SEM micrograph when ethane-di-ol and propan-2-ol are used as an additive shows more finger-like pores and nodules, respectively, in the microstructure of the casted membrane. Furthermore, synergistic effects using water with other additives were also identified using SEM micrograph of casted membrane and it was observed that water with ethane-di-ol and propan-2-ol form contact angle of 98° and 105°, respectively, for 2 weight percent each additive in dope. In this study, the membrane was also cast by dissolving PVDF powder in di.methyl.acetamide solvent with lithium chloride and the effect of the temperature difference between coagulation bath and film temperature was investigated using an SEM micrograph. Overall, it was found that water content and temperature difference aid in developing hydrophobic porous membrane of desired properties for MD applications.

Influence of Spray Drying Parameters on the Formation of β‐Phase Poly(vinylidene fluoride)

AbstractA simple one‐step spraying method to produce poly(vinylidene fluoride) (PVDF) in the desired conformation is presented. The content of the piezoelectric β‐phase is measured at different spray drying conditions and during electrospray. The influence of a strong electrical field and charges on the droplet are investigated separately from the electrospray setup with a pneumatic atomizer. For this purpose, the electric field is integrated into a pneumatic atomization process by a plate capacitor and the charge of the droplets by corona discharge. To investigate the drying properties, the drying temperature and the flow rate of dry air are examined. The presented process offers the possibility to deposit PVDF films or to produce PVDF powders, in their piezoelectric β‐ and γ‐phases or in the nonpolar α‐phase.

Synthesis and Characterization of Organic–Inorganic Complex

An new method is described for fabricating BiFeO3@PVDF composites using sultraviolet light to motivate the surface electronic of BFO conduct reduction system. The synthesis scheme consists of: (a) preparation of BiFeO3 nano particles using Hydrothermal synthesis method. (b) oxidation of the PVDF powders in the effect of the mixed gas (ozone and dioxygen) and sultraviolet light. (c) redox reaction of the oxidated PVDF and BiFeO3 nano particles in the effect of sultraviolet light. The synthesized BiFeO3@PVDF composites show that this method could increase the compatibility between PVDF and BiFeO3 nano particles. Moreover, a formation mechanism for the composite is proposed.

PVDF grafted Gallic acid to enhance the hydrophilicity and antibacterial properties of PVDF composite membrane

A kind of PVDF composite membrane of good hydrophilic performance and antibacterial property was developed via an in-situ blending process. The PVDF-g-PGAL powder was prepared by degrading PVDF powder in alkaline condition, then oxidizing and grafting with Gallic acid (GAL). After mixing the original PVDF and PVDF-g-PGAL powder to prepare the PVDF composite membrane was soaked in NaHSO3 to further improve its hydrophilicity. The oil-in-water emulsion separation efficiency of the composite membrane was regulated by varying the contents of the modified PVDF powder. When the content arrives at 30%, the composite membrane has the pore sizes in the range of 130.2–263.3 nm, the permeation flux of 2419.9L⋅m−2⋅h−1⋅bar−1, the oil rejection rate of 97.39%, the flux recovery rate (FRR) of 94.59% and possesses the good anti-fouling performances during the cross-flow separation of the oil-in-water emulsion with the particle sizes within the scope of 10.1–396.1 nm. In addition, it has excellent antibacterial properties against E. coli and S. aureus, and effectively solves the blocking of membrane pores caused by the surface colonies in application. Therefore, the new composite PVDF membrane has the broad application prospects in the practical treatment of the complex oily wastewater media.

Photocatalytic nanocomposite membranes for high-efficiency degradation of tetracycline under visible light: An imitated core-shell Au-TiO2-based design

Herein, Au-TiO2 nanocomposite photocatalysts were initially constructed through a three-step-synthesis strategy including the sodium citrate reduction method, sol-gel method and high-temperature hydrothermal method. After that, Au-TiO2/PVDF photocatalytic nanocomposite membranes with visible light response were synthesized by a phase conversion process, thereinto, the Au-TiO2 nanocomposite and PVDF powder were mixed into casting solutions by physical blending. Various characterization methods, such as SEM, TEM, FTIR, XRD, XPS, WCA and UV-vis DRS, etc., were used to systematically characterize the micromorphology, structural composition, wettability and optical properties of different samples. The UV-vis DRS results showed that the as-prepared nano-Au doping structure effectively enhanced the utilization factor of visible light in the process of photocatalytic degradation. The antifouling results of BSA adsorption experiments showed that 0.3-Au-TiO2/PVDF composite membranes possessed good antifouling performance. By analyzing the regeneration stability experiments, it could be found that the 0.3-Au-TiO2/PVDF composite membranes also exhibited excellent regeneration stability and easy separation and recovery features. The photocatalytic degradation of different membranes under visible light was investigated with tetracycline. The results showed that the photocatalytic degradation rate of 0.3-Au-TiO2/PVDF nanocomposite membranes reached 75% within 120 min. Moreover, the first-order kinetic linear fitting showed that the k value of 0.3-Au-TiO2/PVDF composite membranes was 0.01212 min−1, which was 2.7 times and 2.0 times higher than that of 0.1-Au-TiO2/PVDF and 0.5-Au-TiO2/PVDF composite membranes. That is to say, photocatalytic activity of 0.3-Au-TiO2/PVDF composite membranes were obviously improved.

Multiple-functional molecularly imprinted nanocomposite membranes for high-efficiency selective separation applications: An imitated core-shell TiO2@PDA-based MIMs design

Development of membrane-associated molecularly imprinted materials with fast and high permselectivity has been significant needed in separation engineering field. Herein, for the first time, a subversive synthesis strategy with hierarchical structure was proposed for the preparation of nanocomposite blended molecularly imprinted membranes (NBMIMs). Artemisinin, the high-efficiency antimalarial drug, was chosen as the template molecule. Instead of the direct modification of nanocomposite on membrane surfaces, the double-bonded TiO2@PDA was initially prepared, the blended membrane synthesis procedure was then conducted through a phase conversion process by using the as-prepared TiO2@PDA and PVDF powder as host materials. Importantly, the double-bonded TiO2@PDA-based nanocomposite in blended membranes was first proposed and applied as imprinting-initiated factor during the next artemisinin-imprinted process, leading the formation of imitated core-shell structure on membrane surfaces. It was no surprise that more excellent rebinding capacity (66.9 mg g−1), fast adsorption kinetics and high permselectivity coefficients (more than 17) were successfully achieved. Furthermore, an important conclusion was also obtained that TiO2@PDA-based nanocomposite from NBMIMs would cause significant enhancement of the rebinding capacity, that is to say, more and more artemisinin-imprinted sites would be synthesized by increasing the dosage of TiO2@PDA until 0.5 g. Therefore, a novel direction for the design and manipulation of MIMs materials had been successfully designed and guided for selective separation of artemisinin.

A novel antiscaling and anti-corrosive polymer-based functional coating

Abstract Carbon nanotubes (CNTs), as a carrier of diethylenetriaminepenta(methylphosphonic acid) (DTPMPA), combining with flake zinc and PVDF powders, were used to fabricate a novel organosilicon epoxy resin-based (EP) composite coating (EP/iDCNTs/Zn/PVDF) for antiscaling and anti-corrosion purposes. Compared with EP coating, the EP/iDCNTs/Zn/PVDF composite coating exhibited unique antiscaling properties with the CaCO3 deposition on the coating surface decreased by 81.6%. It was mainly because the coating surface contains DTPMPA, and Zn2+released by corrosion of Zn powder, which jointly inhibited the deposition behavior of CaCO3. Meanwhile, the fabricated composite coating hardly adhered by CaCO3 crystals which was due to its higher hydrophobicity. Moreover, anti-corrosion tests proved that the prepared composite coating's impedance modulus was about 2 orders higher than that of the EP coating. This was ascribed to the improving shielding effect of fillers and high hydrophobicity of coating, preventing the water and oxygen molecules from penetrating into the composite coating.

Pre-irradiation grafted single lithium-ion conducting polymer electrolyte based on poly(vinylidene fluoride)

In this work, a poly(vinylidene fluoride) (PVDF)-based copolymer is synthesized by grafting two kinds of monomer, 2, 2, 3, 4, 4,-hexafluorobutyl methacrylate (HFMA) and 2-acrylamido-2-methylpropanesulfonic acid (AMPS), onto the PVDF powder with pre-irradiation grafting copolymerization. Then a new single lithium-ion conducting polymer electrolyte (SIPE) is prepared by solution casting of the radiation grafted PVDF-based copolymer powder with subsequent lithiation process. Its chemical structure, crystal form, and membrane morphology are characterized by nuclear magnetic resonance spectroscopy (NMR), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM), etc. The mechanical properties exhibit the elongation at break of 72% and the tensile strength of 28 MPa. Comparatively high values of ionic conductivity, up to 2.08 × 10−5 S cm−1 at 30 °C, are obtained, combined with lithium-ion transference number of 0.93 and stable electrochemically oxidation voltage as high as 4.4 V vs Li/Li+. Except for these promising features, the SIPE cell with lithium ion conduction network has a stable charge/discharge cycling performance with various C-rates at room temperature. As-prepared SIPE shows a great prospect for the application in lithium-ion batteries.

Enhancing proton conductivity via sub-micron structures in proton conducting membranes originating from sulfonated PVDF powder by radiation-induced grafting

We report here submicron-structured proton conducting poly(vinylidene fluoride)-graft-poly(styrene sulfonic acid) (PVDF-g-PSSA) membranes for polymer electrolyte membrane fuel cells (PEMFC). Highly conductive proton exchange membranes were obtained by single-step radiation grafting of sodium styrene sulfonate (SSS) to powder-form PVDF, followed by casting and subsequent solvent evaporation. The obtained submicron structure of membrane through solvent evaporation led to the arrangement of ionic channels proving increasing proton conductivity with the increase in graft level. In addition, a temperature above melting point of PVDF was used for solvent evaporation to allow melted PVDF to fill the formed pores, providing denser structure resulting in improved mechanical properties of the membranes. SSS grafting to PVDF powder was verified by NMR spectroscopy, and resultant membranes were characterized for proton conductivity, water up-take, morphology, mechanical and thermal properties, and fuel cell performance. According to preliminary tests, proton conductivities which were observed to increase with graft level were found to be around 70mScm2 at 35% graft level. Thus, this led to a promising power density of 250mW/cm2 at 650mA/cm2.