PVDF Blend Research Articles

PVDF and PEO Catholytes in Solid‐State Cathodes Made by Conventional Slurry Casting

AbstractAll‐solid‐state Li batteries are desired for better safety and energy density than Li‐ion batteries. However, the lack of a penetrating liquid electrolyte requires a much different approach to the design of cathodes. The solid catholyte must enable good Li+ conduction, form good interfaces with active material particles, and have the strength to bind the cathode together during repeated volume changes. Catholyte formulation is often simply adapted from Li‐ion design principles, adding a Li salt to the PVDF binder. Here we show that such a PVDF binder at 10 wt % loading is a starved catholyte condition that compromises cell performance. By substituting a 70 : 30 blend of PVDF:PEO, performance is improved while maintaining nearly the same areal loading of LFP active material. Increasing the catholyte fraction to 16 % can also improve performance, but in this case the benefit of including PEO is lessened, with PVDF alone being an adequate catholyte. EIS analysis shows that PEO helps to form charge transfer interfaces at 10 % catholyte, but that its inclusion can degrade interfaces when there is ample catholyte at 16 %. It is also shown that catholyte agglomeration can impede bulk Li conduction, indicating that microstructural factors are of critical importance.

Nanoscale phase separation achieved through trace PVDF/PEI blending enhances mechanical and energy storage performance at high temperatures

Due to the development of advanced electronic systems, there is an urgent need for polymer dielectric film capacitors with high breakdown strength (Eb) and high discharge energy density (Ud) at elevated temperatures. Herein, an all-organic blend polymer composite is fabricated by blending polyetherimide (PEI) and a trace amount of Poly(vinylidene fluoride) (PVDF), achieving nanoscale phase separation and forming interfaces between PEI and PVDF grain. The real permittivity (εr) and Eb of blend composites are simultaneously enhanced after PVDF introduction. It is worth noting that increasing the temperature does not reduce the Eb of the PEI/xPVDF blend composite. Our Study shows that optimizing the plasticity and storage modulus of PEI/xPVDF significantly contributes to maintaining Eb at elevated temperatures. Additionally, high temperatures enhance the entanglement of molecular chains at the PVDF-PEI interface, further supporting the preservation of Eb. Finally, a high Eb of 540 MV/m, a high Ud of 5.92 J/cm3 are achieved for the PEI/0.5PVDF blend at 150 °C. This work presents a new approach to enhance the Eb of dielectric polymers by optimizing mechanical properties at high temperature, which providing a different strategy for enhancing the energy storage performance.

High performance gel polymer electrolyte based on P(MMA-co-Sty) and PVDF blend for fast-charging lithium metal batteries with extended cycle life

In the quest for high-energy-density lithium metal batteries (LMBs), the stabilization of lithium (Li) metal anodes during fast charging remains a formidable challenge. In this study, a novel copolymer, Poly(methyl methacrylate-co-styrene) (namely PMS) is synthesized and blended with Poly(vinylidene fluoride) to fabricate a porous gel polymer electrolyte (GPE, namely PMS-PVDF) through the nonsolvent-induced phase separation technique, which significantly enhances the electrochemical stability and fast-charging capabilities of LMBs. The developed GPE exhibits a high ionic conductivity of 5.62 mS cm−1, thereby reducing the formation of detrimental Li dendrites and leading to over 400 h stripping/plating process at 0.5 mA cm−2. Extensive electrochemical tests show that the LMBs with the obtained PMS-PVDF GPE achieve exceptional cycle stability over 600 and 1000 cycles at the C-rates of 0.5 and 3 C, respectively, outperforming traditional electrolytes. Furthermore, the ultra-stability of the quasi-solid-state electrolyte is demonstrated in a 375 mAh pouch cell setup, suggesting an essential trait for the practical application of high-power devices. This work marks a pivotal contribution to the field of energy storage, delivering insights and a clear methodology that pave the way for the development of next-generation LMBs poised for commercial viability.

Impact of KNO3 Concentration on Structural Properties, Dielectric and AC Conductivity Response of 80 PEO:20 PVDF Blend Polymer Electrolytes

Impact of KNO3 Concentration on Structural Properties, Dielectric and AC Conductivity Response of 80 PEO:20 PVDF Blend Polymer Electrolytes

Advancing electrodialysis with dually cross-linked PVDF-based anion exchange membranes having semi-interpenetrating networks

Electrically-driven membrane technology plays a crucial role in water treatment and purification, finding applications in various fields like saline water and wastewater desalination, saline concentration and wastewater recycling. The content of this study is based on dually cross-linking and hot-pressing on a PVDF blend, to fabricate a kind of anion exchange membranes (AEMs) having semi-interpenetrating network and thus improve the defect of the traditional heterogeneous AEMs. The research explores the impact of vinyl imidazole (VIM) and dimethylaminoethyl methacrylate (DMAEMA) monomers, primarily or dually cross-linking, and optimizes the membrane properties through a hot-pressing process. Under these optimized conditions, the resulting membranes exhibit robust mechanical properties and outstanding desalination capabilities, achieving an area resistance of 2.56 Ω cm2 (comparable to standard homogeneous membranes), a desalination rate of 97.26% (outperforming the Neosepta AMX: 76.90%), and a salt limiting concentration of 3.1 M (surpassing the heterogeneous AEM and Neosepta AMX). Notably, this synthesis method is characterized by its cheap raw material and low energy consumption. This research offers valuable insights for the advancement and large-scale implementation of anion exchange membrane desalination.

PVDF-based (V2O5)x. (Mn0.4Fe2.6O4)(2−x), x = [0.2, 0.4, 0.6, 0.8, and 1] nanocomposites for tailoring the optical and nonlinear optical properties of PVDF

Nanocomposites comprising (V2O5)x. (Mn0.4Fe2.6O4)(2−x), where x = [0.2, 0.4, 0.6, 0.8, and 1], were successfully synthesized by milling each single phase of V2O5 and Mn0.4Fe2.6O4 nanostructured samples. We studied the structure and morphology of the prepared samples through X-ray diffraction and scanning electron microscopy. UV–Vis. spectrum analysis was used to study the optical characteristics. As an attempt to improve the optical and nonlinear optical properties of the PVDF blend, the prepared nanocomposites were used as nanofillers for the poly (vinylidene fluoride) (PVDF) polymer. Optical and nonlinear optical properties of the PVDF polymer were tuned using (V2O5)x. (Mn0.4Fe2.6O4)(2−x), where x = [0.2, 0.4, 0.6, 0.8, and 1] nanocomposite. The obtained results showed a tunable spectrum, absorption, refractive index, and dielectric constant at wavelengths ranging from 200 to 800 nm. However, the results showed that the (V2O5)0.6. (Mn0.4Fe2.6O4)1.4, sample was the best for obtaining the lowest transmittance percentage and bandgap energy. The nonlinear optical properties and Kerr effect (quadratic electro-optic effect) showed a significant response, which can be tuned in the range from 200 to 1200 nm of wavelength using the investigated samples. Finally, incorporating (V2O5)x. (Mn0.4Fe2.6O4)(2−x), where x = [0.2, 0.4, 0.6, 0.8, and 1], nanoparticles in the PVDF polymer improved the hydrophilic behavior of the PVDF films. This study suggests a promising nanocomposite material for tunable optoelectronics and useful polymer membranes.

Customizable non-charging material for eliminating electrostatic charge of particles at source

Contact electrification causes the electrostatic adhesion of particles onto surfaces. This causes a vast range of severe problems. In industry, fouling causes blockages of processes (e.g., vessels and pipes) and prevents Process Analytical Technology (PAT) probes from functioning. In research laboratories, adhesion causes expensive powders to be routinely lost during normal operations. To address these wide-ranging problems, this study describes a non-conductive polymeric material that resists triboelectric charging against powders (e.g., pharmaceutical and food). The material is a novel blend of two approved food- and pharmaceutical-grade polymers at a specific proportion. One polymer tends to charge positively (i.e., polyvinyl acetate; PVAc), whereas the other tends to charge negatively (i.e., polyvinylidene fluoride; PVDF), against the targeted powder. The non-charging polymer blend of PVAc and PVDF is successfully designed, translated, and deployed into industrially relevant situations. The polymer blend prevented milk powder and ethylcellulose powder from fouling the stainless-steel surface of a vessel in the food industry (e.g., for blending). It prevented aspirin powder from fouling an NIR probe used for accurate continuous monitoring of moisture during the drying process in a standard pharmaceutical industry glass filter dryer (GFD) for a long time of > 210 min. The original probe stopped functioning within 5 min. It prevented the adhesion of different types of expensive protein and enzyme powders onto tubes (e.g., for storage and transfer) commonly used in research laboratories. Therefore, this non-charging polymer blend is a universal solution for preventing particle adhesion and fouling for different types of processes, industries (e.g., food or pharmaceutical manufacturing), and powders.

Highly durable, perfluorinated Q(PFBE-co-VBC) and PVDF blend anion exchange membranes with interconnected morphological features for electrochemical energy conversion systems

Alkaline anion exchange membrane that possesses fluorocarbon and hydrocarbon backbones demonstrates high stability in electrochemical energy conversion systems.

Homogeneous Blend PVDF Porous Membrane Without Pore-Forming Agent for Water Treatment

Homogeneous Blend PVDF Porous Membrane Without Pore-Forming Agent for Water Treatment

Anion-Conducting Polymer Electrolyte without Ether Linkages and with Ionic Groups Grafted on Long Side Chains: Poly(Alkylene Biphenyl Butyltrimethyl Ammonium) (ABBA).

In this work we report the synthesis of the new ionomer poly(alkylene biphenyl butyltrimethyl ammonium) (ABBA) with a backbone devoid of alkaline-labile C-O-C bonds and with quaternary ammonium groups grafted on long side chains. The ionomer was achieved by metalation reaction with n-butyllithium of 2-bromobiphenyl, followed by the introduction of the long chain with 1,4-dibromobutane. The reaction steps were followed by 1H-NMR spectroscopy showing the characteristic signals of the Br-butyl chain and indicating the complete functionalization of the biphenyl moiety. The precursor was polycondensed with 1,1,1-trifluoroacetone and then quaternized using trimethylamine (TMA). After the acid catalyzed polycondensation, the stoichiometric ratio between the precursors was respected. The quaternization with TMA gave a final degree of amination of 0.83 in agreement with the thermogravimetric analysis and with the ion exchange capacity of 2.5 meq/g determined by acid–base titration. The new ionomer blended with poly(vinylalcohol) (PVA) or poly(vinylidene difluoride) (PVDF) was also characterized by water uptake (WU) and ionic conductivity measurements. The higher water uptake and ionic conductivity observed with the PVDF blend might be related to a better nanophase separation.

Dielectric properties and energy storage performance of PVDF-based composites with MoS2@MXene nanofiller

Hybrid nanofillers designed for polymer dielectric nanocomposites are expected to obtain excellent dielectric energy storage performance by virtue of different morphologies and electrical properties. In this work, the 2D/2D heterostructures of 2D MoS2 grown on the surface of 2D transition metal carbide Ti3C2 MXene (MoS2@MXene) have been successfully obtained through hydrothermal reaction. MoS2@MXene was incorporated into poly (vinylidene fluoride) (PVDF) to form the PVDF based dielectric composites (MoS2@MXene/PVDF) through solution casting method. The composite with 3.47 wt% MoS2@MXene is very flexible with an elastic modulus of 385 MPa, which is not much different with pure PVDF (357 MPa). The maximum electric displacement at room temperature and an electric field of 400 MV/m is 10.96 μC/cm2, moreover the discharged energy density reaches 17.22 J/cm3, which is nearly 4.5 times that of pure PVDF (3.83 J/cm3 at the maximum electric field of 250 MV/m). The dielectric constant of 3.47 wt% MoS2@MXene/PVDF at room temperature and 103 Hz is 24.3, and the loss is only 0.02. Even though the filler content is increased to 12.51 wt%, the loss is only 0.06, and the dielectric constant of the composite film can reach 145.2. Compared with the blend of PVDF and MXene, the dielectric constant of MXene@MoS2/PVDF shows more excellent frequency stability and lower dielectric loss.

Optimizing the Molecular Weight of Poly(vinylidene Fluoride) for Competitive Perfluorosulfonic Acid Membranes

Homogeneous proton exchange membrane with high mechanical strength and low gas permeation is of paramount importance for the application of proton exchange membrane fuel cells (PEMFCs). Herein, the impact of different molecular weight of poly(vinylidene fluoride) (PVDF, Mw = 350 000–1 100 000 g mol−1) on the performance of the perfluorosulfonic acid (PFSA)/PVDF blend membrane is studied systematically for the first time. The mechanical strength of the PFSA/PVDF blend membrane increases and the H2 crossover of PFSA/PVDF blend membrane is decreased with increasing molecular weight of PVDF. Due to the fact that ultra‐high molecular weight PVDF has more long‐chain molecules which can enhance the adhesive strength between PVDF and PFSA, the tensile strength of 25 wt% PVDF5130–PFSA (Mw = 1 100 000) membrane reaches 33.5 MPa with the thickness of 15 μm, 200% higher than that of pure PFSA membrane and 60% higher than that of commercial Nafion 211. The H2 crossover of the blend membrane is 0.69 mA cm−2, much lower than that of commercial Nafion 211 (2.05 mA cm−2). When applied in PEMFCs, the blend membrane shows comparable power density to Nafion 211 with an output of 1.17 W cm−2.

Data Mining of Polymer Phase Transitions upon Temperature Changes by Small and Wide-Angle X-ray Scattering Combined with Raman Spectroscopy.

The complex physical transformations of polymers upon external thermodynamic changes are related to the molecular length of the polymer and its associated multifaceted energetic balance. The understanding of subtle transitions or multistep phase transformation requires real-time phenomenological studies using a multi-technique approach that covers several length-scales and chemical states. A combination of X-ray scattering techniques with Raman spectroscopy and Differential Scanning Calorimetry was conducted to correlate the structural changes from the conformational chain to the polymer crystal and mesoscale organization. Current research applications and the experimental combination of Raman spectroscopy with simultaneous SAXS/WAXS measurements coupled to a DSC is discussed. In particular, we show that in order to obtain the maximum benefit from simultaneously obtained high-quality data sets from different techniques, one should look beyond traditional analysis techniques and instead apply multivariate analysis. Data mining strategies can be applied to develop methods to control polymer processing in an industrial context. Crystallization studies of a PVDF blend with a fluoroelastomer, known to feature complex phase transitions, were used to validate the combined approach and further analyzed by MVA.

Thermo-Responsive Membranes from Blends of PVDF and PNIPAM-b-PVDF Block Copolymers with Linear and Star Architectures

This work was supported by King Abdullah University of Science and Technology, grants REP/1/3848-01-01, URF/1/4040-01-01 and base lines.

Enhanced crystallization behaviors and dielectric performance of poly(vinylidene fluoride) film induced by polyamide-1

Poly(vinylidene fluoride) (PVDF)-based composites attract tremendous attention as dielectric materials. However, their development has been limited due to the raised problem in the in-homogeneous polymer composites. In this work, a novel PVDF-based film incorporated with polyamide-1, containing the highest density of dipole among all polyamides, was prepared to improve the crystallization behaviors and dielectric properties. The results showed that the optimal concentration of polyamide-1 in PVDF was 6 wt.%. The crystallization rate of PVDF was improved in the presence of polyamide-1. Interestingly, the polyamide-1 was conductive to the formation of β form crystal of PVDF, which exhibited great electric performance. The dielectric constant of PVDF increased sharply and loss tangent still kept at a low level of 0.03@100 Hz when the concentration of polyamide-1 was 6 wt.%. This work may provide a new direction to design dielectric materials for PVDF blends.

In-situ grown inorganic layer coated PVDF/PSF composite hollow fiber membranes with enhanced separation performance

Poly(vinylidene fluoride) (PVDF) membranes are widely employed for water treatment but mainly limited by their hydrophobic properties that increase the separation resistance. To make hydrophilic PVDF membranes, inorganic layer coated PVDF blend hollow fiber membranes are reported here. PVDF/polysulfone (PSF) blend hollow fiber membranes with pore size of ~110 nm were fabricated using PolarClean as a green solvent. Then, a facile and green method was employed to in-situ grow an inorganic layer (including TiO2 and Al2O3 layers) on these high strength membranes. Pluronic L61 was used as a dispersing agent to distribute the precursors in isopropanol, and enhanced adhesive strength between the polymer membrane and inorganic particles as characterized by XPS. The inorganic layers on the PVDF/PSF membrane surface both improved the mechanical strength from 7.7 MPa to 9.2 MPa and decreased the membrane roughness from ~50 nm to ~10 nm. The water permeance of the composite membranes can be finely tuned from 50 to 500 Lm−2h−1bar−1. In addition, the resulting membranes simultaneously enhanced the separation performance and anti-fouling performance characterized by bovine serum albumin (BSA) rejection behavior and flux recovery rate (FRR), respectively. The best BSA rejection and FRR of the PVDF/PSF-inorganic composite membranes reach 95% and 72.2%, respectively. The anti-fouling performance of composite membranes is mainly attributed to the decreased membrane roughness and enhanced hydrophilic properties compared with pristine PVDF/PSF membranes. Furthermore, the in-situ grown inorganic layers on the PVDF/PSF membrane surface effectively prevent foulants from blocking the pore channels as they are easily washed by the hydraulic washing method.

Crystallization Monitoring of Semicrystalline Poly(vinylidene fluoride)/1-Ethyl-3-methylimidazolium Hexafluorophosphate [Emim][PF6] Ionic Liquid Blends

The electroactive characteristics of poly(vinylidene fluoride) (PVDF) are widely and increasingly being used in technological applications, where controlling the crystallization of the PVDF is of utmost importance. The nucleation and growth of crystals in the β or γ electroactive phases, or in the nonelectroactive α phase, depends on a number of factors that, despite the studies carried out, are still to be properly understood, in particular, when blended with specific active fillers. In this context, the crystallization of PVDF blended with the ionic liquid (IL) 1-ethyl-3-methylimidazolium hexafluorophosphate ([Emim][PF6]) has been analyzed. Both components are capable of crystallizing from the melt. The growth of the crystalline phases of PVDF during isothermal crystallization at different temperatures has been monitored using Fourier transform infrared (FTIR) spectroscopy. The isothermal crystallization kinetics of PVDF and the melting temperatures of both PVDF and IL were characterized by differential scanning calorimetry, and the microstructures of the blends were analyzed by optical and electron microscopy. It is observed for [Emim][PF6]/PVDF blends that the isothermal crystallization from the melt between 120 and 162 °C produces PVDF crystallites in the β and γ electroactive phases, while the formation of α-phase crystals is nearly suppressed. The morphology of the blends is altered by the addition of IL, which results in the separation of solid phases at room temperature. In addition, [Emim][PF6] remains liquid when mixed with the amorphous PVDF chains due to the cryoscopic descent.

A Succinct Review on the PVDF/Imidazolium-Based Ionic Liquid Blends and Composites: Preparations, Properties, and Applications

Poly(vinylidene fluoride) (PVDF) is a versatile thermoplastic fluoropolymer with intriguing characteristics, which is receiving considerable attention from researchers in many areas. Recently, PVDF and its copolymer, such as poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) have been blended with ionic liquids to produce blend and composite materials for target applications. In this succinct review, two types of ionic liquids that are utilized for the preparation of PVDF and PVDF-HFP blends and composites, namely, hydrophilic and hydrophobic imidazolium-based ionic liquids, are reviewed. In addition, the effect of the ionic liquids on the physicochemical properties of the PVDF and PVDF-HFP blends and composites, is described as well. On top of that, a multitude of applications of the blends and composites are also succinctly reviewed. This review may give inspirations to the polymer blend and composite researchers in diversifying the applications of thermoplastic fluoropolymers through the utilization of ionic liquids.

Simultaneous enhancement of discharge energy density and efficiency in the PMMA and PVDF blend films via introducing the Ni(OH)2 nanosheets

The progress of dielectric capacitors with superior energy storage density (Ue) has drawn widely attentions in recent years. However, most studies improve the Ue at the cost of their energy storage efficiency (η), which greatly limits their practical applications. In this study, a nanocomposite film based on the nickel hydroxide (Ni(OH)2) and the polymethylmethacrylate and polyvinylidene fluoride blend polymer (PMMA/PVDF) is designed and prepared (x vol%-Ni(OH)2-PMMA/PVDF). It has been found that introducing Ni(OH)2 and PMMA into ferroelectric PVDF is not only able to improve the dielectric constant and breakdown field, but also able to suppress the dielectric loss and leakage current density of nanocomposite films, leading to enhanced Ue and η simultaneously. Furthermore, the finite element simulation was adopted to demonstrate the mechanism of compatible improvement on the dielectric constant and breakdown field in the nanocomposite films, respectively. An excellent Ue of 14.5 J/cm3 and η of 71.7% are realized in the 3 vol%-Ni(OH)2-PMMA/PVDF nanocomposite film at 445 MV/m. The significantly improved Ue in this composite is 181% higher than that of the pristine PMMA film and 250% higher than that of the pure PVDF film. Thus, this study might provide a new path to design the nanocomposite films with high Ue and η simultaneously.

Preparation, characterization and impedance spectroscopic studies of Na+ ion conducting PEO + PVDF-blended polymer electrolytes

The films of poly (ethylene oxide) (PEO) and poly (vinylidene fluoride) (PVDF)-based blended polymer electrolyte films complexed with sodium perchlorate (NaClO4) salt were prepared using the solution casting method. The complexation of NaClO4 salt with the blend of polymers PEO and PVDF was confirmed by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. The melting temperatures were measured by differential scanning calorimetry (DSC). The surface morphology was examined by scanning electron microscopy (SEM). The prepared films were subjected to electrical impedance spectroscopy (EIS) to investigate ionic conductivity, dielectric and electrical modulus studies. It was observed that adding a small amount of PVDF to the PEO host polymer improves the interaction between the ions and the polymer and results in more ionic dissociation. Consequently, the number of active mobile carriers in the polymer matrix increases. The ionic conductivity studies have shown the maximum conductivity 2.84 × 10−6 S/cm at 303 K for the polymer blend 0.8PEO + 0.2PVDF complexed with 5 wt% NaClO4 and it is attributed to a decrease in crystallinity. Ionic transport numbers of various prepared samples were measured using Wagner’s polarization technique.