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The field of multifunctional energetics encompasses a range of materials including propellants, explosives, and pyrotechnics that possess the ability to be manipulated through various characteristics that can be switched between go and no-go, or those that have controllable energy release levels or have additional functions beyond energetic output. The development of multifunctional energetics harnessing electromechanical or piezoelectric properties of polymeric materials or binder systems has garnered increasing interest in recent years. Among polymers, fluoropolymers such as poly(vinylidene fluoride) (PVDF) and copolymers such as poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)], which are used as the binder and oxidizer in the energetic formulations, have demonstrated the highest piezoelectric coefficients. In this study, we fabricated piezo-energetic composite films using aluminum nanopowders (10 wt. % active content) as fuel and P(VDF-TrFE) (70/30) as an oxidizer and investigated the piezoelectric response using a small-scale drop weight setup. Additionally, we employed a shaker setup to investigate the response of the films to vibrations. Our findings demonstrate that these piezo-energetic films can replicate the behavior of a commercial PVDF gauge at relatively low-pressure impacts, indicating their potential use as shock or pressure sensors in various fields, as well as an accelerometer gauge. Additionally, aging studies of up to one year indicated minimal loss in the energetic content of the created films, enabling the use of energetic gauges for an extended period. Our findings support the effectiveness of piezo-energetic composite films as pressure sensors or accelerometers and highlight their potential for energetic applications. [ABSTRACT FROM AUTHOR]

Poly(vinylidene fluoride) (PVDF) has been widely studied because of its various crystal phase transformations as well as its special dielectric, piezoelectric, and other electrical properties. In this study, a temperature gradient (T-gradient) was constructed for studying the temperature dependence of the crystallization behavior of PVDF and the heterogeneous nucleation effect of multiwall carbon nanotubes (MWCNTs). The nanoscale structure of PVDF was investigated through three different dimensions using FTIR for the surface, WAXD/SAXS for the bulk and AFM for the cross-section. The results showed that low temperature and a heterogeneous nucleating agent were both conducive to the formation of the γ phase of PVDF. The distance of MWCNT nucleation effect is about 15 μm, and it is more significant in 0–5 μm. The content of the γ phase reached 77% when Tc was lower than 61 °C. The higher content and lower crystallite size of the γ phase lead to a higher dielectric constant, which can lay a foundation for its future application in the field of dielectrics. [ABSTRACT FROM AUTHOR]

[Display omitted] • Composite polymer electrolytes were successfully prepared using solution casting and electrospinning method. • LaFeO 3 increases the amorphous regions of poly(vinylidene fluoride hexafluoropropylene) enhancing the ionic conduction. • Solution casted electrolyte with 5 wt% LaFeO 3 shows very low polarization voltage and excellent electrochemical compatibility against lithium metal. • Solid-state battery using solution casted electrolyte with 5 wt% LaFeO 3 shows superior cycling stability and electrospun electrolyte with 5 wt% LaFeO 3 exhibits better rate performance. Composite polymer electrolytes (CPEs) are a promising alternative to flammable conventional liquid electrolytes for high-safety lithium-ion batteries. Establishing low-cost filler that enhances the amorphous nature of polymer in the CPEs and exhibits efficient Lewis acid-base interaction between fillers and anions of lithium salt, leading to improved dissociation of salts for enhanced conduction, is indispensable. In this work, for the first time, we construct a solid composite polymer electrolyte of poly(vinylidene fluoride hexafluoropropylene) embedded LaFeO 3 (LFO) particles prepared by solution casting and electrospinning methods and study their performances. The 5 wt% LFO filler embedded CPE made by means of solution casting and electrospinning methods exhibited the highest ionic conductivity of 5.9 × 10-4 and 1.49 × 10-3 S cm−1 at room temperature and electrochemical stability window up to 4.6 and 4.45 V, respectively. Further, as-assembled solid-state lithium-ion batteries using electrospun CPE showed an initial discharge capacity of 166 mAh/g at 0.1C-rate and solution-casted CPE showed excellent cycling stability with 98.6 % capacity retention at 0.3C-rate even at 50th cycle. Such excellent performance originated from the introduction of the LFO particles as filler into the polymer matrix to enhance the ionic conductivity, mechanical strength and lithium metal compatibility of the resulting CPEs. [ABSTRACT FROM AUTHOR]

This study explored the impact of hot press parameters on lead zirconate titanate (PZT)/poly(vinylidene fluoride) (PVDF) composite films designed for force‐sensing applications. The systematic fraction (PZT/PVDF), pressure, temperature, and time during hot pressing processes are subject to variation. The focus is on the resulting composite film thickness and its subsequent influence on the piezoelectric properties, which are essential for the performance of force sensors. The present study investigated the characteristics and performance of PZT/PVDF composite films with fraction ratios 2/5, 5/5, and 7/3 and hot pressure of 10, 40, and 60 MPa and temperature at 150 °C for 2 h. The characterization of these films was conducted using X‐ray diffraction, Fourier transform infrared spectroscopy, atomic force microscopy, and scanning electron microscopy. The piezoelectric properties (d33 and d31) were measured using impact and extraction tests to evaluate the performance of films with applied forces. The results show that the highest piezoelectric coefficients (d33 and d31) were determined to be 35.8 and 12.60 pC N−1, with fraction ratios of 7/3 and 2/5. The study revealed a positive correlation between the PZT/PVDF ratio and sensitivity, indicating that an increase in the ratio leads to an increase in sensitivity. Conversely, a negative relationship was observed between the impact load and the sensor sensitivity, suggesting that an increase in the impact load results in a sensitivity decrease. The results of this work demonstrate the great potential of piezoelectric PZT/PVDF composite films in force sensors for small load applications. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Studying the electromechanical response behavior of piezoelectric thin films under different loading conditions is of great value for the development and optimization of piezoelectric sensors and flexible portable electronic devices. This paper establishes the theory of large deflection vibration of rectangular four-edge simply supported piezoelectric thin films using the energy method, and analyzes the electromechanical response characteristics of vibration force (including resonant frequency and nonlinear vibration). Meanwhile, the electromechanical response behavior of Poly(vinylidene fluoride) (PVDF) films under different loading conditions (static and harmonic vibration) is analyzed. The study investigates the nonlinear vibration characteristics and resonance frequency variations under different film sizes and thickness conditions in the case of various loading conditions. The developed model can predict the resonance frequency associated with the plate dimensions. This study is of great significance for the research and application of laminated piezoelectric film sensors. [ABSTRACT FROM AUTHOR]

Films of piezoelectric poly(vinylidene fluoride) (PVDF) and its copolymer P(VDF-TrFE) have been studied intensively for their potential application in piezoelectric sensing devices. The present work focuses on tuning the piezoelectric properties of P(VDF-TrFE) films via incorporating Ag and polydopamine co-decorated PZT (Ag@PDA@PZT) particles. Ag@PDA@PZT particles can effectively improve the β-phase content and piezoelectric properties of P(VDF-TrFE) films. The highest open-circuit voltage and short-circuit current of P(VDF-TrFE)-based flexible pressure sensors incorporating Ag@PDA@PZT particles are ~30 V and ~2.4 μA, respectively. The flexible sensors exhibit a response to different body movements, providing a practical and potentially useful basis for human−machine interface applications. [ABSTRACT FROM AUTHOR]

Graphene oxide-silver poly(vinylidene fluoride) membranes (PVDF@GO-Ag) were successfully synthesized by the electrospinning method, which exhibited a high catalytic activity using the hydrogenation of 4-nitrophenol (4-NP) as a model reaction in a batch reaction study. The hybrid membranes doped with 1 wt% GO and 2 wt% Ag (PVDF-1-2) exhibited the most desired performance for the catalytic reduction of 4-NP. Importantly, PVDF-1-2 exhibited excellent cycling stability in 10 catalytic cycle tests and was highly amenable to separation. This property effectively addresses the significant challenges associated with the practical application of nanocatalysts. Furthermore, density-functional theory (DFT) calculations have demonstrated that the GO-Ag nanocomposites exhibit the strongest adsorption capacity for 4-NP− when a specific ratio of GO and Ag is achieved, accompanied by the loading of Ag nanoclusters onto GO. Additionally, the study demonstrated that an increase in temperature significantly accelerated the reaction rate, in line with the van't Hoff rule. This study provides an effective and environmentally friendly solution for the treatment of 4-NP in wastewater. [ABSTRACT FROM AUTHOR]

In response to the demand for miniaturization and lightweighting in the electronics industry, achieving enhanced energy density of dielectrics is crucial. Constructing nanocomposites consist of ceramic fillers and polymer matrix is an effective strategy in this regard. To address the adverse coupling between polarization and breakdown strength of the nanocomposites, a series of BaTiO3@SiO2 nanofillers with customizable SiO2 shell coverage degrees (90°, 180°, and 360°) is designed and synthesized by surface‐confined winding assembly of SiO2 on the surface of BaTiO3. When a half area of BaTiO3 core is coated by SiO2 layer, it is defined as 180°. A larger coverage degree implies better reduction of leakage current injection, and more effective suppression of local electric field concentration. However, it also leads to a more pronounced reduction in the polarization. 180° BaTiO3@SiO2 demonstrates the most effective mitigation of the adverse coupling between polarization and breakdown strength in nanocomposites. The 180° BaTiO3@SiO2/Poly(vinylidene fluoride) (PVDF) nanocomposite achieves high breakdown strength while maintaining relatively higher polarization intensity, for example, the energy density reaches 20.64 J cm−3 at 650 MV m−1, which is 2.62 times of pure PVDF. This work reveals the growth mechanism of customizable SiO2 shell coverage degrees on BaTiO3 surfaces, providing an effective strategy for high‐performance dielectrics [ABSTRACT FROM AUTHOR]

Highlights As the energy demand continuously increases, polymer‐based materials have attracted much attention for energy storage systems as dielectric capacitors due to their higher power density and charge–discharge rate than lithium‐ion batteries and supercapacitors. However, it is necessary to increase the energy density of dielectric capacitors. In this context, poly(vinylidene fluoride‐co‐hexafluoropropylene), PVDF‐HFP, matrix nanocomposites are produced by solution casting method reinforced with hexagonal boron nitride (hBN) nanoparticles and silane‐modified boron nitride nanosheets ‐BNNSs‐ (BNNS‐VTS) up to 10 wt.% filler content. The effects of filler content and surface modification of hBN/BNNSs on PVDF‐HFP matrix nanocomposites' microstructure, phase evolution, crystalization behavior, dielectric properties, and energy storage performance are discussed. 4% hBN/PVDF‐HFP nanocomposite demonstrates 641 MV·m−1 of breakdown strength and 23.2 J·cm−3 of discharged energy density due to hexagonal boron nitride's excellent electrical insulating behavior. The achieved values are 3.0 and 10.5 times superior to the values of the neat thin film, respectively, and they are noteworthy among hBN‐ or BNNS‐reinforced PVDF‐based nanocomposites, even in multi‐layered structures. Furthermore, 4% hBN/PVDF‐HFP presents a giant charge–discharge energy efficiency (92%). It is thus demonstrated that hBN/PVDF‐HFP nanocomposites hold a great potential to be used in energy storage applications as flexible and lightweight dielectric capacitors. PVDF‐HFP matrix nanocomposites for electrical energy storage as flexible dielectric capacitors hBN NPs and silane‐modified BNNSs are reinforced into the matrix by 0–10 wt.%. The effects of filler content and surface modification of hBN/BNNSs are discussed. 4% hBN loading results in 23.2 J·cm−3 energy density and 92% efficiency at 641 MV·m−1 breakdown strength. Those metrics are relatively high in hBN‐ or BNNS‐reinforced PVDF‐based nanocomposites. [ABSTRACT FROM AUTHOR]

Ferroelectric flexible polymer composite films of poly(vinylidene fluoride) (PVDF) with different weight percentages (10.0%, 20.0%, 30.0%, 40.0%, and 50.0%) of (Bi0.5Ba0.25Sr0.25) (La0.5Ti0.5) O3 were synthesized by solvent casting method. Analysis using the x‐ray diffractometer and Fourier transform infrared spectroscopy tools revealed the presence of the different phases (α, β) of PVDF. Scanning electron microscope morphology illustrates the homogenous dispersion of ceramics particles in the matrix. The differential scanning calorimetry curve (under 25–400°C) gives the value of melting temperature (Tm=169.98°C) and percentage crystallinity is about 29.45% for 50 wt.% composite. The findings demonstrated that the composite has good thermal stability up to 169.98°C. Dielectric analysis shows ferroelectric and dielectric behavior and also distinguishes α and β phases of PVDF. It was found that the composite film containing 50 wt.% (Bi0.5Ba0.25Sr0.25) (La0.5Ti0.5) O3 had a dielectric constant (εr) of 38 (at 100 Hz) and dielectric loss of 0.059, which are the maximum among the samples. The relative permittivity rises with an increase in filler content due to electrostatics and interfacial polarization between PVDF (CH2CF2 dipole) and ceramic. The real and imaginary part of impedance spectroscopy with frequency (Cole–Cole plots) for composite (10.0–50.0 wt.%) at 25°C are also investigated. The current study provides a fresh perspective on the fact that PVDF‐(Bi0.5Ba0.25Sr0.25) (La0.5Ti0.5) O3 composite system has improved thermal stability and dielectric characteristics. [ABSTRACT FROM AUTHOR]

One of the critical principles of green chemistry and environmental sustainability is to avoid using harmful solvents in chemical processes. In this study, a novel solvent‐free method was employed to prepare poly (vinylidene fluoride) (PVDF) hollow fiber composite membranes with stable crystalline and porous structures. Utilizing the cold‐hot stretching method, the crystalline structure and orientation of PVDF were effectively redesigned, resulting in improved mechanical and penetration properties of the membrane. Additionally, an investigation into the internal crystalline structure of the PVDF hollow fiber membrane was conducted, focusing on crystalline changes induced by ion‐dipole interactions. Results indicated that the addition of neutral ion‐dipole functional particles (N‐P) promoted the conversion of α crystalline to β crystalline, leading to stable β crystalline and controllable pore sizes in the prepared PVDF hollow fiber membrane. Furthermore, the internal crystalline structure significantly contributed to enhancing the membrane's mechanical properties and penetration performance. Notably, a PVDF hollow fiber with high β crystalline content was achieved through 150% cold‐hot stretching and the addition of 20. wt% N‐P further enhanced the β‐crystalline content in the membrane. This study presents a promising approach for reducing solvent consumption and minimizing environmental impact in the field of environment‐friendly membrane fabrication. [ABSTRACT FROM AUTHOR]

Poly(vinylidene fluoride) (PVDF) film shows great potential for applications in the electrostatic energy storage field due to its high dielectric constant and breakdown strength. Polymer film surface engineering technology has aroused much concern in plastic film capacitors as an effective strategy for improving dielectric properties and energy storage characteristics. In this paper, biaxially oriented PVDF (BOPVDF) films were prepared by melt extrusion-biaxial stretching and treated with organic impregnation using hydrofluoroether. The insulation properties and energy storage density of the biaxially oriented films were significantly improved by a simple film formation post-treatment. The impregnation treatment effectively suppressed the leakage current of the film at a high electric field. The impregnated BOPVDF exhibited excellent insulation properties with a breakdown strength of 747.84 kV/mm. Meanwhile, the energy storage density of 16.26 J/cm3 with a charge–discharge efficiency of 78.41% was obtained at 700 kV/mm. This research provided a simple way to improve the energy storage performance of PVDF-based polymers by organic impregnation treatment and has the feasibility of achieving large-scale production. [ABSTRACT FROM AUTHOR]

This study investigates the influence of two types of binders (aqueous and nonaqueous) on the LiFePO4 (LFP) electrode processing and its electrochemical properties. Specifically, polyvinylidene fluoride (PVDF) and polyacrylic acid (PAA) were dissolved in NMP (N‐methyl‐2‐pyrrolidone) or the aqueous solvent (H2O) at varying mass ratios of 5%, 10%, and 15%. Binder durability and inertness were assessed by immersing prepared LFP electrodes in an electrolyte comprising 1.0 M LiPF6 in EC:DEC:DMC (1:1:1 in vol%). Notably, PVDF/NMP 10% and PAA/H2O 10%‐based electrodes displayed good durability without peeling. Electrochemical characteristics were evaluated through cycling voltammetry and galvanostatic cycling with potential limitation. The PAA/H2O 10%‐based‐LFP electrode exhibited a specific capacity of ~148.9 mAh g−1 with a Coulombic efficiency (CE) of around 97.27%, surpassing PVDF/NMP 10%. The graphite||PAA/H2O 10%‐based‐LFP electrode in a full cell demonstrated higher capacity and superior retention after 30 cycles. In a pouch cell (6 cm × 4 cm), utilizing graphite||LFP with PAA/H2O 10%, a capacity of 25.5 mAh was achieved, maintaining 93% capacity with a CE of about 99% after 30 cycles at a rate of 0.1C. [ABSTRACT FROM AUTHOR]

Dielectric capacitor is an important component of power systems, but its low dielectric polarization and undesirable dielectric loss have still held back the development of miniaturized microelectronic devices. Hence, we reported core@shell structured fillers with a conducting material@insulating material double-shell to improve the dielectric performance of the poly (vinylidene fluoride) (PVDF) composites. The hybrid fillers introducing ultra-short carbon nanotube (SSCNT) as an inner layer between BaTiO 3 (BT) as a core and silica (SiO 2) as an outer shell were synthesized. As the thickness of the insulating shell is enough thin, the BT@SSCNT@SiO 2 /PVDF composites exhibit an enhanced dielectric constant and a concurrently suppressed dielectric loss with the decreasing thickness. The composite incorporating the filler with the thinnest SiO 2 shell has the highest dielectric constant of 12.27 and the lowest dielectric loss of 0.023 at 20 wt% filler loading where the breakdown strength is about 15 less than the maximum value of 192.5 kV/mm. Furthermore, the hybrid fillers endow the composites with impressively stable dependence on frequency in a wide range of 102∼105 Hz. The achievement can be ascribed to the conducting property of the SSCNT inner layer and the suitable thickness of the insulating outer layer. They can synergetically provide the composites with an optimized polarization effect at a broad frequency resulting from the improved electrical field. This work reveals that a proper structure of the core@conducting material@insulating material core@double-shell filler can be an approach to optimize the overall dielectric performance of the polymer-based composites with high energy storage density. [ABSTRACT FROM AUTHOR]

Considering the growing demand for piezoelectric energy harvesting from ferroelectric–polymer-based composite materials and the benefits associated with them, this work focuses on piezoelectric energy harvesting from poly(vinylidene fluoride)-co-hexafluoropropylene (PVDF-HFP)/BZT-BCT/GO hybrid composite films synthesized via solution casting followed by the hot-pressing method. Structural properties were analyzed using XRD, FTIR, and Raman spectroscopy. SEM micrographs confirmed the presence of pores in the synthesized samples that provided an added advantage toward enhancing its piezoelectricity. The dielectric and ferroelectric properties were studied, in which the dielectric constant increased up to 20.69, and the remnant polarization was found to be 0.0560 μ C cm−2. A PUND analysis was performed to validate the data obtained from the static hysteresis loop. Piezoelectric charge and voltage coefficients were measured, which reach up to "−31 pC N−1" and "−252.5 mV m N−1," respectively. Figure of merit, electromechanical coupling coefficient, and quality factor of the as-synthesized samples were calculated. A harvester prototype was fabricated to investigate the energy harvesting performance of the synthesized hybrid composite films. The highest open circuit voltage, short circuit current, and power density were recorded as 2.19 V, 24.17 nA, and 468.43 μ W m−2, respectively. The harvested energy can be utilized for powering low-power devices, showing the real-time applicability of the synthesized hybrid composite films. [ABSTRACT FROM AUTHOR]

Passive daytime radiative cooling (PDRC) is an innovative and sustainable cooling technology that holds immense potential for addressing the energy crisis. Despite the numerous reports on radiative coolers, the design of a straightforward, efficient, and readily producible system remains a challenge. Herein, we present the development of a hierarchical aligned porous poly(vinylidene fluoride) (HAP-PVDF) film through a freeze-thaw-promoted nonsolvent-induced phase separation strategy. This film features oriented microporous arrays in conjunction with random nanopores, enabling efficient radiative cooling performance under direct sunlight conditions. The incorporation of both micro- and nano-pores in the HAP-PVDF film results in a remarkable solar reflectance of 97% and a sufficiently high infrared thermal emissivity of 96%, facilitating sub-environmental cooling at 18.3 °C on sunny days and 13.1 °C on cloudy days. Additionally, the HAP-PVDF film also exhibits exceptional flexibility and hydrophobicity. Theoretical calculations further confirm a radiative cooling power of 94.8 W·m−2 under a solar intensity of 1000 W·m−2, demonstrating a performance comparable to the majority of reported radiative coolers. [ABSTRACT FROM AUTHOR]

Silicon (Si) -based materials have been identified as a potential alternative anode owing to their superior theoretical capacity compared to conventional graphitic carbon. Nevertheless, the huge volume change (approximately 300%) that occurs while cycling still hampers this system from 100% practical applications. Silicon-monoxide (SiOx)-based anode materials, on the other hand, are being explored extensively due to their unique properties such as high theoretical capacity, formation of Li2O and LiSiO4 during initial lithiation process that act as a natural volume buffer matrix to accommodate volume changes and formation of a stable solid electrolyte interphase layer, which improves the cyclability and capacity retention. Although poly (vinylidene fluoride) (PVdF) is widely used as a binder, the weak van der Waals forces between PVdF and silicon-based particles fail to bind particles effectively, when substantial volume change occurs. Herein, we prepare a series of SiOx-Si-C electrodes with different binders poly (acrylic acid) (PAA), carboxyl methyl cellulose (CMC) and their blends as binder. The prepared polymeric blends are subjected to thermal, morphological, mechanical and physico-chemical analyses. The Li/ SiOx-Si-C cell assembled with 100% PAA as binder delivered a discharge capacity of 1908 mAh g−1 on its first cycle and 724 mAh g−1 on its 100th cycle with a fade in capacity of 11.8 mAh g−1 per cycle. Upon the incorporation of CMC in the PAA blend the cycling performance was found to be poor. Among the various investigated compositions, the electrode with sole poly (acrylic acid) as a binder offers the highest discharge capacity and this is attributed to the high concentration of the functional (carboxylic) group which forms strong hydrogen bonds with - OH groups on the SiOx or carbon surface. The interfacial properties of the polymeric binders are thoroughly investigated by spectroscopies and electrochemical tests. [ABSTRACT FROM AUTHOR]

Poling parameters and barium titanate (BT) content significantly affect the piezoelectric and dielectric properties of poly(vinylidene fluoride) (PVDF). Selecting the best possible values for these process parameters is indeed a significant challenge. In this study, piezoelectric nanocomposites for high-energy conversion were prepared by mixing PVDF with BT. The dependence of piezoelectric and dielectric properties on process parameters was investigated. The input parameters, including poling temperature, time and voltage, and BT mass fraction, were considered as input variables. A Box-Behnken Design was used to design and analyze the experiments. ANOVA was performed to study the significance of poling parameters and BT mass fraction. An Artificial Neural Network was used to model PVDF-based nanocomposite properties as a function of the four process parameters. A genetic algorithm was applied to search for the optimal poling conditions and BT mass fraction. The optimal combination leads to a d33 coefficient of 25.259 pC/N, a permittivity of 24.282, and a β-phase fraction (F(β)) of 95.435%. These results were experimentally validated, and the errors were 9.789, 0.338, and 0.305%, respectively. Following the optimization, a PVDF-based nanocomposite with excellent piezoelectric and dielectric properties (d33 = 28pC/N, permittivity = 24.2, F(β) = 95.7%) was fabricated for energy conversion applications. [ABSTRACT FROM AUTHOR]

Using the solution cast method, researchers prepared Poly(vinylidene fluoride) (PVDF)/Poly(ethylene oxide) (PEO) blend doped with various weight ratios of Cobalt oxide nanoparticles (Co3O4 NPs). XRD analysis revealed a remarkable increase in the amorphous nature of the nanocomposites as the Co3O4 concentration climbed. The Notable alterations were revealed by the FT-IR spectra, revealing interactions between the PVDF/PEO blend and Co3O4 NPs. We found a significant red shift in the fundamental absorption edge of nanocomposites films using UV–visible spectroscopy. As the concentration of Co3O4 ions rose, the direct bandgap of PVDF/PEO film decreased significantly, from 5.39 eV to 3.96 eV, while the Urbach energy increased. Thermal analysis in the range of 30–500 °C revealed a remarkable improvement in the thermal stability of the nanocomposites compared to their pure PVDF/PEO blend. The endothermic melting temperature (Tm) of the PVDF/PEO blend is 130 °C was calculated from DSC analysis. To delve into the electrical behavior of the films, its conductivity was examined using an AC impedance analyzer over a broad frequency range of 100 Hz–7 MHz at room temperature. As the Co3O4 NP content ramped up and the frequency climbed, the material's electrical conductivity responded in kind, showing a consistent upward trend. The electrical conductivity of the nanocomposite films, as a function of frequency, neatly follows Jonscher's equation. The PVDF/PEO blend containing 2%Co3O4 NPs reigned supreme in terms of ionic conductivity, boasting a remarkable 6.5 × 10–4 Scm−1 at room temperature. The dielectric constant increases with Co3O4 concentration, according to dielectric permittivity studies, because of interfacial polarization at the PVDF/PEO and Co3O4 interfaces. The findings show that the films made from nanocomposites have improved optical, thermal, electrical, and dielectric properties. The gathered data suggests that the Co3O4 nanoparticles doped PVDF/PEO mix films are a novel, easy-to-work-with, and promising material for a range of applications, such as optoelectronics, electronics, and other flexible energy storage devices. [ABSTRACT FROM AUTHOR]

Achieving precisely defined and stable component binding is of great interest for composite materials and batteries, but very challenging owing to the lack of effective strategies to manipulate the binder itself. Here, a concept of single‐particle binding (SPB) strategy is proposed based on a polymer‐sol binder to conquer the above challenge. To do that, a polymer‐sol binder is first prepared by dispersing commercial poly(vinylidene fluoride) (PVDF) powder into a mixture of its solvent and non‐solvent with a rational weight ratio of 8:2. Then, by manipulating this PVDF‐sol microfluid, PVDF particles are uniformly and singly introduced onto the surface of other components, such as graphene oxide nanosheets and battery separators. Results further show that the temperature‐induced sol–gel transition of the microfluid finally generates single‐particle fusion and strong component binding with commercial separators (31.6 N m−1). Meanwhile, a surface‐swelling model is proposed to understand its binding mechanism. Finally, this unique SPB strategy has been employed to fabricate nacre‐like nanocomposites with advanced self‐polarized piezoelectricity (23.0 mV N−1), and component‐integrated batteries with robust separator/electrode interphases. This SPB strategy with the PVDF‐sol binder may inspire significant studies on polymer sol, microfluidics, nanocomposites, battery interfaces and beyond. [ABSTRACT FROM AUTHOR]

The local interaction within poly(vinylidene fluoride)/poly(3,4‐ethyelenedioxythiophene):poly(styrelenesulfonate) (PVDF/PEDOT:PSS) composite films has been explored in this study. Vibrational and impedance spectroscopy were used extensively to investigate the potential interactions within the moieties of PVDF and PEDOT:PSS in the composite. The increased concentration of PEDOT:PSS used as additives enhanced the dielectric constant of the composite films significantly. Both the AC conductivity and the estimated mobility also increased in the composite films with increasing additives. X‐ray absorption spectroscopy gave an insight into the local chain interactions within the polymer composite films. A shift in the C K‐edge toward higher energy confirmed the local interaction of the polymer moieties, suggesting a change in the polymer chain structure due to the possible association of moieties. [ABSTRACT FROM AUTHOR]

In this approach, nanocomposites of PVDF/PMMA/CTAMag films have been successfully synthesized. Modified Maghnite was used as inorganic reinforcement. In this study, nanocomposite polymers were developed based on a mixed matrix of poly(vinylidene fluoride) (PVDF) and poly(methyl methacrylate) (PMMA) of composition (80/20 w/w) in dispersion containing 0, 1, 3, 5 and 7 wt % fillers of organomodified montmorillonite nanoclay (CTAMag) in the melt state. The results obtained by scanning electron microscopy (SEM), XRD traces and FTIR spectra highlighted the homogeneous flexible character of the PVDF/PMMA/CTAMag films and their intercalated and intercalated/exfoliated surface morphology, in addition to the presence of PVDF α, β and γ phase crystallites in these complex films. The increased presence of the modified clay in the host matrix of the PVDF/PMMA blend significantly influenced the melting temperature and the degree of crystallinity of the PVDF crystallites. The scattering of the dielectric spectra, which covers a wide range of frequencies from 20 Hz to 1 GHz, indicates the presence of the phenomenon of interfacial polarization associated with the dielectric capacitance complex at lower frequencies in these composites at 27 °C. The mechanical properties of these composites were evaluated as a function of the load and the mixed matrix of these composites. [ABSTRACT FROM AUTHOR]

In this paper, boron (B)‐doped biphasic calcium phosphate (BCP)/poly(vinylidene fluoride) (PVDF) membrane scaffolds were developed by the combination of non‐solvent induced phase separation and lyophilization processes. In addition, the effects of the synthesized B‐incorporated BCP powders on the properties of the fabricated scaffolds were investigated. The physicochemical and morphological properties of the scaffolds were characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy. The physical properties were evaluated by surface wettability and swelling measurements, whereas the mechanical properties were investigated by tensile strength measurements. The thermal behavior was determined by differential scanning calorimetry, the β‐crystallization ratio was calculated by FTIR, and the β‐phase structure was characterized by X‐ray diffraction. The bioactivity was evaluated in the simulated body fluid, and the cytotoxicity of the scaffolds was also investigated by performing in vitro cell culture experiments. The results showed that the incorporation of B into the PVDF matrix improved the hydrophilicity while reducing the degree of swelling of the scaffolds. Tensile strength was slightly reduced by the powder content, but yet the strength of all scaffolds was mechanically compatible with native bone. Increasing the B content up to 0.5 and 1 wt.% was improved the thermal properties, the β‐crystalline phase fraction, and thus the piezoelectricity. Furthermore, B‐doped BCP/PVDF‐based scaffolds significantly promoted bioactivity, cell viability, and proliferation without cytotoxicity, compared to the PVDF scaffold, depending on the B content. In conclusion, our results indicate that the PVDF‐based composites in the form of membrane scaffolds that support bone growth have the potential to be highly sought‐after candidates in the field of biomedical applications. [ABSTRACT FROM AUTHOR]

A straightforward scalable method for synthesizing β-poly (vinylidene fluoride) polymer foam from a sugar template has been used. A characteristic β-phase of the foam was confirmed by infrared and micro-Raman spectroscopy with significant enhancement observed after poling. The electrical polarization of the foam revealed a ferroelectric nature with dielectric strength higher than 30 kV/cm which is close to the commercial value. Poled samples had a dielectric constant of 5.5, higher than the value of the unpoled sample (3.05). These values appear stable over the low-frequency range from 1 kHz to 1 MHz. Significant reverse behavior was observed at higher frequencies from 300 GHz to 3 THz frequencies. It was found that the open-cell foam with a porosity of 88% has the lowest dielectric constant value (1.07 at 1.8 THz, reaching 1.04 at 2.9 THz) compared to the foam with 20% porosity (2.17 at 1 THz, reaching 1.83 at 3 THz). Furthermore, the Maxwell Garnett model, in conjunction with THz imaging, confirmed the impact of porosity on dielectric properties. These findings pave the way for the efficient fabrication of ferroelectric porous polymer structures that can be used in dielectric switching at the kHz–THz frequency range. [ABSTRACT FROM AUTHOR]

Copolymers based on vinylidene fluoride are potential materials for ferroelectric memory elements. The trend in studies showing that a decrease in the degree of crystallinity can lead to an unexpected increase in the electric breakdown field is noted. An analysis of the literature data reveals that in fluorine-containing ferroelectric polymers, when using a bipolar triangular field, the hysteresis loop has an unclosed shape, with each subsequent loop being accompanied by a decrease in the dielectric response. In this work, the effect of the structure of self-polarized films of copolymers of vinylidene fluoride with tetrafluoroethylene and hexafluoropropylene on breakdown processes was studied. The structure of the polymer films was monitored using infrared spectroscopy (IR) and X-ray diffraction. Kelvin probe force microscopy (KPFM) was applied to characterize the local electrical properties of the polymers. For the films of the first copolymer, which crystallize in the polar β-phase, asymmetry in the dielectric response was observed at fields greater than the coercive field. For the films of the copolymers of vinylidene fluoride with hexafluoropropylene, which crystallize predominantly in the nonpolar α-phase, polarization switching processes have also been observed, but at lower electric fields. The noted phenomena will help to identify the influence of the structure of ferroelectric polymers on their electrical properties. [ABSTRACT FROM AUTHOR]

A dual-functional material was fabricated to mimic the periosteum for guided bone regeneration. Poly(vinylidene fluoride) (PVDF) was fabricated into a gold-coated electrospun membrane. The gold-coated PVDF membranes were observed and characterized for their morphology and structural formation using light microscopy and differential calorimetry, respectively. Hydrophilicity, mechanical behavior, and electrical properties were evaluated from the results of the contact angle, universal testing machine, and an inductance–capacitance–resistance meter, respectively. MC3T3E1 osteoblast cells were seeded onto PVDF membranes with and without the gold coating. The cells on the seeded membranes were cultured under either a non-dynamic condition or a dynamic condition by shaking at 100 rpm (1.67 Hz). In vitro testing was performed to evaluate the biological performance (cell proliferation and viability), protein analysis, alkaline phosphatase (ALP) activity, and calcium content. PVDF with the gold coating had a higher melting temperature, hydrophilicity, and dielectric constant than without the gold coating. The gold-coated PVDF membranes showed a lower Young's modulus than the uncoated PVDF membranes. The seeded gold-coated and uncoated PVDF membranes under the dynamic condition had higher cell proliferation, viability, protein amount, ALP activity, calcium content, and calcium deposition than the PVDF membrane without either the gold coating or under the dynamic condition. Finally, the results deduced that the gold-coated PVDF membranes were able to mimic the periosteum with a dual function and showed promise for guided bone regeneration. [ABSTRACT FROM AUTHOR]

Barium titanate (BaTiO3, BT)/poly (vinylidene fluoride, PVDF) composites containing 0%–50% of ceramic filler volume fraction were fabricated by spin‐coating method, and it was shown that the permittivity of BT/PVDF composites increased with the addition of ceramic filler. In order to enhance the interfacial bonding between the two phases, the surface modification treatment of BT ceramic particles was carried out using different mass fractions of γ‐Aminopropyl‐triethoxysilane (KH550). The results indicated that the dielectric properties of the modified composites were enhanced. The dielectric constant of the BT/PVDF composite with 10 vol.% ceramic filler treated with 1 wt.% KH550 is 20.3, which is twice as much as pure PVDF. A model of BT/PVDF dielectric composite was employed by using COMSOL Multiphysics to simulate and analyze the effects of filler particle size, volume fraction, and degree of dispersion on the properties of composite dielectric films from the perspective of microstructural. Calculated results show that the addition of ceramic particles triggers local electric field distortion, which affects the dielectric properties of the composites. Meanwhile, the degree of dispersion of the filler also affects the breakdown resistance of the composite material, when the filler is uniformly dispersed, the local electric field is reduced, which effectively enhances the breakdown resistance of the material. Finite element simulation analyzes the macroscopic dielectric properties from a microstructural point of view, which is beneficial for further understanding of ceramic‐polymer composites. Highlights: The dielectric properties of the polymer matrix were enhanced by doping BT.The KH550 can enhance the dispersion of BT particles in the PVDF.The surface‐modified BT improved the dielectric properties of the composite.COMSOL simulation confirmed the effectiveness of the interface modification. [ABSTRACT FROM AUTHOR]

Polymer-ceramic nanocomposite films using double perovskite ceramic phase offer promising prospects for developing multifunctional flexible films in general and energy storage system in specific. The manganese and iron-based double perovskite is emerging as potential system for various functional applications. In the present attempt, we explore the application of poly (vinylidene fluoride) (PVDF):Nd2MnFeO6 (NMFO) composite films as an energy storage system. The NMFO was synthesized by sol–gel combustion method, and its structure is confirmed by X-ray diffraction (XRD) analysis, which demonstrates the formation of a single-phase monoclinic system with the space group P21/n. Detailed structural information is extracted through Rietveld refinement of XRD data using full-prof software. To create flexible nanocomposite films, various volume percentages (10%, 20%, 30%, 40%, and 50%) of NMFO ceramic nanoparticles are incorporated as fillers in the PVDF polymer matrix using the solution casting method. The structural properties of the developed nanocomposite films are investigated using XRD and FTIR studies, while microstructural features are investigated through SEM analysis. Dielectric properties of nanocomposite thin film are studied at different frequency ranges (1–200 kHz) using a LCR meter. Furthermore, the ferroelectric behavior of the nanocomposite thin film was systematically examined using a PE Loop Tracer. Remarkably, the nanocomposite thin film containing approximately 30 wt% of NMFO exhibited significantly higher dielectric permittivity, low dielectric loss, and increased remanent polarization, coercivity, and spontaneous polarization at room temperature. These findings highlight the potential of this nanocomposite film as a flexible energy storage system. [ABSTRACT FROM AUTHOR]

The increased micro-capacitance of a poly (vinylidene fluoride) (PVDF) matrix can effectively improve the piezoelectric properties of the composite material. This work used chemically modified carbon nanotubes (CNTs) as the main reinforcement material. Atom transfer radical polymerization (ATRP) was used to graft polyionic liquids (PILs) with different hydrophilic anions to the CNTs' surfaces. Solution casting and compressive melt molding were used to prepare the PVDF-composite piezoelectric films. Micro-capacitance formed by the PIL grafted CNTs dispersed well in the PVDF matrix, and their effects on the crystalline form and piezoelectric properties were studied. The hydrophobic hexafluorophosphate anion (-PF6-) can significantly improve the CNTs dispersion and enhance the micro-capacitance formation in the PVDF matrix. During solution crystallization, the synergistic effect of CNTs and PIL on the PVDF and the solvent effect made the content of β phase of PVDF/CNTs@PIL-PF6 film reach 80.2%, resulting in a high dielectric constant of 188 and a piezoelectric coefficient of 36. In the process of melt crystallization, due to shear stretching and extrusion, the CNTs@PIL-PF6 had an obvious nucleation effect on the polar crystalline phase of PVDF, with a β phase content up to 99.3%, leading to the higher dielectric constant of 530 and the piezoelectric coefficient of 31. The current discovery provides a development direction for smart piezoelectric polymer matrix composites, which have great potential in preparing piezoelectric energy storage materials. [ABSTRACT FROM AUTHOR]

Amphiphilic block copolymers of poly(ethylene glycol) (PEG) and poly(vinylidene fluoride) (PVDF) were successfully synthesized by growing poly(vinylidene fluoride) on PEG‐chain transfer agent (PEG‐macro‐CTA) using reversible addition–fragmentation chain transfer (RAFT) polymerization. MeO‐PEG‐XA, and XA‐PEG‐XA macro‐CTAs (XA refers to the xanthate moiety), synthesized by esterification of MeO‐PEG‐OH (20,000 g mol−1) and HO‐PEG‐OH (20,000 g mol−1) with 2‐bromopropionyl bromide followed by reaction with potassium ethyl xanthate, were used to synthesize MeO‐PEG‐b‐PVDF and PVDF‐b‐PEG‐b‐PVDF, respectively. The synthesized macro‐CTAs and block copolymers were characterized by NMR (1H, 13C and 19F), FTIR, and SEC. Furthermore, the PVDF/PEG block copolymer formation was proved by 1H DOSY NMR. The thermal properties were determined by TGA and DSC. The crystallinity and electroactive phases were revealed by XRD and FTIR. The size and shape of self‐assembled block copolymers in DMF/water mixtures were determined by DLS, TEM and critical micelle concentration with fluorescence spectroscopy. The influence of molecular weight and PVDF content on the properties of copolymers is discussed. [ABSTRACT FROM AUTHOR]

Wearable pressure sensors have attracted significant attention owing to their potential applications in health monitoring and connectivity to internet‐based apps. Polymers such as poly(vinylidene fluoride) have been used in sensors. However, being petroleum‐derived materials, they do not decompose and remain in the soil when disposed. Poly(l‐lactic acid) (PLLA) is a promising material because of its biodegradable nature and its derivation from plant‐based materials. In addition, the electrospun PLLA fiber mat contains real charges and exhibits electromechanical properties. However, the detailed charging properties of the PLLA fiber mats remain unclear. Herein, the charge distribution of these fiber mat is presented, and a charging model of the fiber mat and a numerical model of the output charges from the fiber mats with electrodes are proposed. Additionally, the retention properties of the stored charges are determined using surface potential measurements at different temperatures. In addition, a self‐power‐generating touch sensor and mask‐type sensor are developed using biodegradable materials produced from biomass. These studies contribute to the improvement in the charge properties of PLLA fiber mats and the resulting wearable biodegradable sensors. [ABSTRACT FROM AUTHOR]

Quantitative converse piezoelectric coefficient (d33) mapping of polymer ultrafine fibers of poly(acrylonitrile) (PAN), as well as of poly(vinylidene fluoride) (PVDF) as a reference material, obtained by rotating electrospinning, was carried out by piezoresponse force microscopy in the constant-excitation frequency-modulation mode (CE-FM-PFM). PFM mapping of single fibers reveals their piezoelectric activity and provides information on its distribution along the fiber length. Uniform behavior is typically observed on a length scale of a few micrometers. In some cases, variations with sinusoidal dependence along the fiber are reported, compatibly with a possible twisting around the fiber axis. The observed features of the piezoelectric yield have motivated numerical simulations of the surface displacement in a piezoelectric ultrafine fiber concerned by the electric field generated by biasing of the PFM probe. Uniform alignment of the piezoelectric axis along the fiber would comply with the uniform but strongly variable values observed, and sinusoidal variations were occasionally found on the fibers laying on the conductive substrate. Furthermore, in the latter case, numerical simulations show that the piezoelectric tensor's shear terms should be carefully considered in estimations since they may provide a remarkably different contribution to the overall deformation profile. [ABSTRACT FROM AUTHOR]

Flexible and cost‐effective poly(vinylidene fluoride) (PVDF)‐based composites having excellent piezo performance are quite interesting for developing actuators, sensors, and nanogenerators. In this work, a hybrid PVDF‐based nanocomposite consisting of a fixed quantity of titanium dioxide (TiO2) and varying quantities of reduced graphene oxide (rGO) for increased mechanical and piezoelectric performance is reported for the first time. Compared to pure PVDF, there is a significant enhancement in mechanical properties for hybrid nanocomposites. The highest piezoelectric voltage as well as current values of 10.2 V and 0.78 μA are recorded for a hybrid nanocomposite containing 1 wt% of rGO for continuous finger‐tapping operation. A multicriteria decision‐making (MCDM)‐based material selection and optimization technique called TODIM is applied, and a sensitivity study is carried out to select the best material for mechanical energy harvesting applications. A hybrid nanocomposite based on PVDF‐TiO2 with 1% rGO loading is the most suitable material according to the TODIM (an acronym in Portuguese for Interactive Multicriteria Decision Making) approach. Highlights: PVDF‐TiO2‐rGO nanocomposites are fabricated by solvent casting.TODIM optimization technique is applied for the best material selection among samples.Material ranking consistency shows the reliability of the TODIM method.Conductive rGO increases interfacial polarization, resulting in enhanced ε values.An increment of 88% and 104% in tensile strength and elastic modulus, respectively. [ABSTRACT FROM AUTHOR]

Ferroelectric materials have important applications in transduction, data storage, and nonlinear optics. Inorganic ferroelectrics such as lead zirconate titanate possess large polarization, though they are rigid and brittle. Ferroelectric polymers are light weight and flexible, yet their polarization is low, bottlenecked at 10 μC cm−2. Here we show poly(vinylidene fluoride) nanocomposite with only 0.94% of self-nucleated CH3NH3PbBr3 nanocrystals exhibits anomalously large polarization (~19.6 μC cm−2) while retaining superior stretchability and photoluminance, resulting in unprecedented electromechanical figures of merit among ferroelectrics. Comprehensive analysis suggests the enhancement is accomplished via delicate defect engineering, with field-induced Frenkel pairs in halide perovskite stabilized by the poled ferroelectric polymer through interfacial coupling. The strategy is general, working in poly(vinylidene fluoride-co-hexafluoropropylene) as well, and the nanocomposite is stable. The study thus presents a solution for overcoming the electromechanical dilemma of ferroelectrics while enabling additional optic-activity, ideal for multifunctional flexible electronics applications. Wang et al. report large nonvolatile polarization in stretchable polymer ferroelectrics incorporating perovskite nanocrystals. The built-in electric field from poled ferroelectrics stabilises Frenkel defects via interfacial coupling, which can also enhance the polarization of nonferroelectrics. [ABSTRACT FROM AUTHOR]

In this study, we proposed a novel method that integrates density functional theory (DFT) with the finite field method to accurately estimate the polarizability and dielectric constant of polymers. Our approach effectively accounts for the influence of electronic and geometric conformation changed on the dielectric constant. We validated our method using polyethylene (PE) and polytetrafluoroethylene (PTFE) as benchmark materials, and found that it reliably predicted their dielectric constants. Furthermore, we explored the impact of conformation variations in poly(vinylidene fluoride) (PVDF) on its dielectric constant and polarizability. The resulting dielectric constants of α- and γ-PVDF (3.0) showed excellent agreement with crystalline PVDF in experiments. Our findings illuminate the relationship between PVDF's structural properties and its electrical behavior, offering valuable insights for material design and applications. [ABSTRACT FROM AUTHOR]

BACKGROUND: Crop recognition is the basis of intelligent agricultural machine operations. Visual perception methods have achieved high recognition accuracy. However, the reliability of such methods is difficult to guarantee because of the complex environment of paddy fields. Tactile sensing methods are not affected by background or environmental interference, and have high reliability. However, in an ideal environment, the recognition accuracy is not as high as that of the visual method. RESULTS: To balance the accuracy and reliability of rice plant recognition, a combined visual–tactile method was proposed in this study. A rice plant recognition device was developed with a poly(vinylidene fluoride) sensor embedded inside the device as a tactile perceptron and a graphic designed as a visual perceptron. The primary role of the tactile perceptron is to initially recognize rice plants and provide a time point for image capture for visual perception. The main role of the visual perceptron is to extract features from the captured images and recognize rice plants again. The results of tactile and visual recognition were eventually fused to achieve accurate recognition of rice plants. CONCLUSION: The contact speed between the recognition perceptron and rice–weed was selected for the field performance test based on the real situation of paddy field operation. The results showed that the accuracy and reliability of rice plant recognition decreased as the travelling speed of the paddy field operation machine increased. The results of this study provide a basis for intelligent farm machinery operations in rice fields. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Nanofibrous materials generated through electrospinning have gained significant attention in tissue regeneration, particularly in the domain of bone reconstruction. There is high interest in designing a material resembling bone tissue, and many scientists are trying to create materials applicable to bone tissue engineering with piezoelectricity similar to bone. One of the prospective candidates is highly piezoelectric poly(vinylidene fluoride) (PVDF), which was used for fibrous scaffold formation by electrospinning. In this study, we focused on the effect of PVDF molecular weight (180,000 g/mol and 530,000 g/mol) and process parameters, such as the rotational speed of the collector, applied voltage, and solution flow rate on the properties of the final scaffold. Fourier Transform Infrared Spectroscopy allows for determining the effect of molecular weight and processing parameters on the content of the electroactive phases. It can be concluded that the higher molecular weight of the PVDF and higher collector rotational speed increase nanofibers' diameter, electroactive phase content, and piezoelectric coefficient. Various electrospinning parameters showed changes in electroactive phase content with the maximum at the applied voltage of 22 kV and flow rate of 0.8 mL/h. Moreover, the cytocompatibility of the scaffolds was confirmed in the culture of human adipose-derived stromal cells with known potential for osteogenic differentiation. Based on the results obtained, it can be concluded that PVDF scaffolds may be taken into account as a tool in bone tissue engineering and are worth further investigation. [ABSTRACT FROM AUTHOR]

Free-standing flexible poly(vinylidene fluoride)-barium strontium titanate (PVDF-BST) composite films loaded with 5 vol% of Ba0.7Sr0.3TiO3 submicronic particles have been synthesized. The synthesized PVDF-BST composite film was quenched in ice water as quenching strongly affects its crystalline phase, dielectric and energy storage behavior. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) studies confirmed that quenching leads to the evolution of the β-phase of PVDF in the PVDF-BST composite films. At 1 kHz, the dielectric constant of the quenched film is ~ 17, which is higher than that of the unquenched film, i.e. ~ 15. At 460 kV/cm, the energy density of the quenched film is 2.5 times higher (~ 4.8 J/cc) as compared to the unquenched film (1.9 J/cc). Significant improvement in the dielectric constant and energy density is attributed to the formation of β-phase of PVDF in PVDF-BST composite film. Mechanism for β-phase formation by quenching at low temperatures has also been suggested. [ABSTRACT FROM AUTHOR]

Highly hydrophilic and antifouling poly(vinylidene fluoride) (PVDF) ultrafiltration membranes are developed with excellent permeation using a zirconium‐based metal–organic framework (MOF‐801). MOF‐801 is synthesized by a solvothermal method using zirconium(IV) oxychloride octahydrate (ZrOCl2⋅8H2O) and fumaric acid. The chemical functionality of MOF‐801 is studied by Fourier transform infrared (FTIR) spectroscopy and X‐ray diffraction (XRD) whereas surface morphology and elemental composition are probed by scanning electron microscopy (SEM)/energy‐dispersive X‐ray analysis (EDX). The PVDF/MOF‐801 membranes are characterized in terms of FTIR, XRD, FESEM/EDX and atomic force microscopy. The performance of the hybrid PVDF/MOF‐801 membranes in terms of pure water flux and antifouling ability is found to be improved compared with bare PVDF membranes. The wettability of the membranes is measured by water contact angle and found to be 76.7° for bare PVDF membrane, which decreases upon the addition of MOF‐801 to 55.1° due to the increase in surface hydrophilicity. A notable increase in roughness of 226.29 nm and a porosity of 67.91% is observed for the addition of 2 wt% MOF‐801 in PVDF membrane matrix. The flux recovery ratio of the hybrid membrane is increased from 66.4% to 89.6% and from 68.3% to 85.2% for bovine serum albumin (BSA) and humic acid (HA) separation, respectively. In addition, the reversible and irreversible fouling performance during the rejection of BSA (93%) and HA (88%) indicates the enhanced antifouling property of the PVDF/MOF‐801 membranes. A zone of inhibition test evidences the outstanding antibiofouling activity of the PVDF/MOF‐801 membranes against E. coli and S. aureus. Overall results demonstrated the suitability of hybrid PVDF/MOF‐801 membranes for water and wastewater treatment. © 2023 Society of Industrial Chemistry. [ABSTRACT FROM AUTHOR]

Poly(vinylidene fluoride) (PVDF) is a promising piezoelectric and pyroelectric material for energy harvesting applications. This paper investigates the electrical outputs of PVDF microarrays using both simulation studies and theoretical calculations. The finite element method in COMSOL Multiphysics® is utilized to model PVDF microarrays and simulate their responses under mechanical loading and temperature changes. Theoretical calculations are also performed to estimate the piezoelectric and pyroelectric voltage outputs using established mathematical formulas. A series of PVDF microarrays are modeled in two dimensions with defined geometry, materials, boundary conditions, and parametric sweeps of wind speed and temperature. The simulation results for electrical outputs show good agreement with the theoretical calculations, demonstrating the validity of both approaches. The maximum voltage outputs are on the order of 10−3 V for the range of wind speeds from 6.5 to 11 m/s and temperatures from 319.3 to 336.3 K. In addition, the mechanical and thermal sensitivities are quantified. This work provides a framework for design and optimization of PVDF‐based energy harvesters. The combined methodology enables characterization of the relationships between operational conditions, PVDF microarray properties, and electrical outputs. [ABSTRACT FROM AUTHOR]

Current hydrophilic modification strategies improve the antifouling ability of membranes but fail to completely eliminate the fouling of emulsified oil droplets with a wide size distribution. Constructing membranes with superior anti‐oil‐fouling ability to resist various oil droplets especially at high permeation fluxes is challenging. Here, the fabrication of a zero‐oil‐fouling membrane by grafting considerably high coverage of zwitterionic polymer and building defect‐free hydration defense barrier on the surface is reported. A uniform layer of protocatechuic acid with COOH as abundant as existing in every molecule is stably deposited on the membrane so as to provide sufficient reactive sites and achieve dense grafting of the zwitterionic polymer. The coverage of zwitterionic polymer on the membrane plays a crucial role in promoting the antifouling ability to emulsified oil droplets. The poly(vinylidene fluoride) membrane with 93% coverage of the zwitterionic polymer exhibits zero oil fouling when separating multitudinous oil‐in‐water emulsions with ≈0% flux decline, ≈100% flux recovery, and a high water flux of ≈800 L m−2 h−1 bar−1. This membrane outperforms almost all of the reported membranes in terms of the comprehensive antifouling performance. This work provides a feasible route for manufacturing super‐antifouling membranes toward oil/water separation application. [ABSTRACT FROM AUTHOR]

Poly(vinylidene fluoride) (PVDF) is predominantly characterized by alternating CH2 and CF2 units in a polymer backbone, originating from the head-to-tail addition of monomers or regular propagation. Due, to a small extent, to inverse monomer addition, so-called defect structures occur which influence the macroscopic properties of PVDF significantly. The amount of defect structures in the material is determined by the polymerization conditions. Here, the temperature dependence of the fraction of defect structures in PVDF obtained from polymerizations between 45 and 90 °C is reported. We utilized 19F-NMR spectroscopy to determine the fraction of defect structures as a function of temperature. To derive kinetic data, the polymerization of VDF is considered a quasi-copolymerization described by the Terminal Model involving four different propagation reactions. Based on the experimentally determined temperature-dependent fractions of defect structures, the known overall propagation rate coefficient, and taking into account the self-healing behavior of the macroradical, the Arrhenius parameters of the individual propagation rate coefficients were determined using the Monte Carlo methods. [ABSTRACT FROM AUTHOR]

Piezoelectric polymers, such as polyvinylidene fluoride (PVDF), have an extensive range of potential applications in the field of flexible electronic devices. This study offers a comprehensive and in-depth exploration of the structural, energetic, electrical, mechanical, and piezoelectric properties of the α, β, and γ phases of PVDF, utilizing the PBE-D3 functional and other DFT functionals. Special attention is given to the impact of van der Waals (vdW) correction within the PVDF system. Through a comparison with existing literature, the influence of D3 correction on the properties of PVDF is assessed. The findings reveal that D3 correction significantly affects calculations related to PVDF's crystal structure, energy, and electronic structure, demonstrating remarkable performance, particularly in enhancing the accuracy of mechanical property computations. This research provides a novel academic perspective, yielding a profound understanding of PVDF properties, and affords a more precise theoretical foundation for its applications in electronic devices and sensors. [ABSTRACT FROM AUTHOR]

In this work, poly(vinylidene fluoride) (PVDF)‐bismuth vanadate (Bi4V2O11; BVO)‐sodium dodecyl sulfate (SDS) composite films are fabricated by the solution casting method. The frequency dependence of the dielectric and electric performances of the resultant PVDF‐BVO‐SDS composites on various weight percentages of SDS contents is investigated. The results demonstrate that the three‐component PVDF‐BVO‐SDS composites have a superior dielectric constant (96) and suppressed dielectric loss (<1) at 102 Hz for 20 wt% of SDS contents. The surface morphology of the PVDF‐BVO‐SDS composites shows that SDS is successfully reinforced on the PVDF‐BVO matrix with better homogeneity. The ac conductivity of the PVDF‐BVO‐SDS composites is also improved, which is helpful for the enhancement of the dielectric constant and relatively low loss in the composites. Moreover, the PVDF‐BVO‐SDS composite also exhibits a larger value of the dielectric constant (96) than the pristine PVDF matrix, which is 15 times higher than that of the pristine one. These significantly enhanced dielectric and electrical characteristics of PVDF‐BVO‐SDS composites will fulfill the practical criteria for their use in high dielectric‐constant capacitors and energy storage devices. [ABSTRACT FROM AUTHOR]

A facile solvent casting technique has been reported in the fabrication of surface hydroxylated ZnFe2O4 (h‐ZFO) nanoparticles (NPs) filled with poly(vinylidene fluoride) (PVDF) as a matrix. The h‐ZFO filler particles are synthesized from neat ZnFe2O4. The dielectric and electric performance of polymer‐based composites is much related to the interface binding between filler particles and polymer matrix. In this work, the surface alternation technique employed a new path is developed to improve the compatibility between ZFO particles and the PVDF matrix. These PVDF‐ZFO composites were studied by X‐ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The h‐ZFO‐PVDF and ZFO‐PVDF composites are carefully analyzed by dielectric and electric properties by a wide range of frequencies. However, the morphological analysis exhibits uniform dispersion of the h‐ZFO NPs in the PVDF matrix. The h‐ZFO‐PVDF composites have a dielectric constant of about 35 for 1.5 wt.% of filler contents. Moreover, the h‐ZFO‐PVDF composites have lower dielectric loss than PVDF‐ZFO composites. It is suggested that the strong interaction between h‐ZFO filler particles and the PVDF matrix is the main reason for the improvement of dielectric properties. The outcomes of these methods have great potential for making high dielectric constants and relatively suppressed loss PVDF‐ZFO composites for advanced practical applications. [ABSTRACT FROM AUTHOR]

Manufacturing of clean energy is an important topic of research for modern life. This paves the way toward investigating easy manufacturing; high-performance energy storage materials. In this sense, conducting polymers such as polyaniline (PANI) are modified with graphene (G) then bound with poly vinylidene fluoride (PVDF) and poly tetrafluoro ethylene (PTFE) to enhance their electronic properties to be used as electrode material in energy storage applications. Furthermore, molecular modeling based on density functional theory at B3LYP/LanL2DZ level of theory was utilized to study the interaction between PANI; G; PVDF and PTFE. Some important properties are calculated such as the total dipole moment (TDM), HOMO/LUMO energy gap (ΔE), and molecular electrostatic potential (MESP). TDM of PANI was found to be 3.994 Debye and increased to 6.010, 9.012, and 9.822 Debye for PANI/G/PTFE, PANI/G/PVDF/PTFE, and PANI/G/PVDF, respectively. ΔE of PANI is 4.353 eV and decreased because of the interaction of PANI with G and polymer binders to reach 3.507, 3.095, and 2.127 eV for PANI/G/PTFE, PANI/G/PVDF, and PANI/G/PVDF/PTFE, respectively. From MESP result, the reactivity and electronic properties increased with the interaction of PANI with G and polymer binders. PANI/G/PVDF/PTFE composite was dedicated as the most suitable candidate for electrode material for many applications. [ABSTRACT FROM AUTHOR]

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