Vinylidene Fluoride Research Articles

Variations in the Ferroelectricity and Piezoelectricity of Poly(vinylidene fluoride) Accompanying the Phase Transformation

Variations in the Ferroelectricity and Piezoelectricity of Poly(vinylidene fluoride) Accompanying the Phase Transformation

Enhancing piezoelectric properties of PVDF-HFP composite nanofibers with cellulose nanocrystals

With the increasing interest in flexible self-powering energy devices, piezoelectric polymers such as poly(vinylidene fluoride) (PVDF), PVDF-trifluoroethylene (PVDF-TrFE and poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) have garnered substantial research attention. Among these, PVDF-HFP has demonstrated immense research potential in harvesting mechanical energy and converting it to electric energy. It is also particularly attractive due to its low cost compared to some other PVDF co-polymers. In this study, PVDF-HFP nanofibers were produced by electrospinning with cellulose nanocrystal (CNC) employed as a filler to improve their piezoelectric performance. Smooth and bead-free fibers were obtained with up to 1 wt% of CNC in the solution. The inclusion of CNC increased the uniformity of fiber diameter and improved thermal stability. Higher CNC concentration (2–3 wt%) engendered agglomeration and adversely impacted the conversion of non-polar phase to electroactive phase for PVDF-HFP molecules. At the optimal CNC concentration of 1 wt%, the voltage and current sensitivities for 1 cm2 samples were obtained as 0.146±0.048 mV/mN and 0.009±0.003 nA/mN, respectively. The open-circuit voltage output of 2.69±1.11 V was achieved under an average impact force of 40 N, and this increased with increased magnitude and frequency of the applied force. The mechanical properties of composite nanofibers maximized at 0.5 wt% CNC with tensile strength of 37.85±4.35 MPa, elastic modulus of 124.96±42.17 MPa, and strain at failure of 82.32±14.84 %. The improved piezoelectric and mechanical properties of the CNC-aided electrospun PVDF-HFP fibers will open new pathways for flexible energy harvesting systems.

Charging Properties of Electrospun Poly(l‐lactic acid) Submicrofiber Mat and Its Electrical Applications

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.

Investigation of the effect of permeation and antifouling characteristics of hybrid poly(vinylidene fluoride) membranes tailored with ZIF‐67 metal–organic frameworks

AbstractHerein the ZIF‐67, a hydrophilic cobalt‐based zeolitic imidazolate framework is synthesized and incorporated with a poly(vinylidene fluoride) (PVDF) to fabricate hybrid ultrafiltration membranes by phase inversion method. The characteristics of PVDF/ZIF‐67 membranes are examined using different analytical techniques such as Fourier‐transform infrared spectroscopy, X‐ray diffractometer, scanning electron microscope, atomic force microscope, and contact angle analysis. The membrane performance is probed using pure water flux (PWF), bovine serum albumin (BSA), and humic acid (HA) rejection. The maximum water flux of 162.5 Lm2 h−1 with BSA and HA rejection of 97% and 98.2%, respectively, exhibited by 1.5 wt% ZIF‐67. The contact angle value is reduced from 83.5 to 58.6° indicating the increase in hydrophilic nature of PVDF membranes by the addition of ZIF‐67. The presence of ZIF‐67 in the PVDF membrane matrix showed outstanding anti‐bacterial properties against Escherichia coli and Staphylococcus aureus. Overall, the PVDF/ZIF‐67 ultrafiltration membranes demonstrate the potential for water treatment applications.

Uniaxially drawn poly (L-lactic acid)/ poly (vinylidene fluoride) polymer blend as a promising piezoelectric material: Hysteresis and resonance spectroscopy study

This study explores the potential for piezoelectricity in a blend of polyvinylidene fluoride (PVDF) and poly-L-lactic acid (PLLA) prepared using the solution casting method. Dielectric frequency measurements across a range of 102 to 106 Hz revealed piezoelectric resonance within a broader dielectric relaxation regime. Analysis of the resonance spectra for length and width vibrational modes enabled the determination of the piezoelectric tensor components of the PVDF/PLLA blend. The blend exhibited enhanced ferroelectric polarization reversal, remnant polarization, and coercive field compared to pristine PVDF samples. The piezoelectric constants d31 and d14 (d36 of the blend) were determined. Mechanical drawing and poling techniques were employed to generate multiple piezoelectric constants, allowing for efficient energy harvesting from various directions. This flexible blend offers promising prospects for versatile energy conversion applications.

Antibacterial PVDF Coral-Like Hierarchical Structure Composite Film Fabrication for Self-Cleaning and Radiative Cooling Effect.

Passive radiative cooling (PRC) is a zero-energy-consumption technology that reflects sunlight and radiates heat to cold outer space. In this work, a porous poly(vinylidene fluoride)-poly(methyl methacrylate) (PVDF-PMMA) composite film is fabricated by decorating zinc-imidazolate metal-organic framework (MOF) (ZIF-8) particles obtained by phase inversion. Due to the competent scattering via the coral-like hierarchical structures and the vibration excitations of specific functional groups, the prepared film exhibits good solar reflectance (92.6%) and intermediate infrared emittance (99.1%), with an average sub-ambient cooling of 10.4 °C under a solar radiation intensity of 0.6 AM1.5. Additionally, poly(vinylidene fluoride) has a low surface energy, while the ZIF-8 particles and coral-like hierarchical structures enhance the surface roughness, endowing the surface with significant superhydrophobicity characterized by a water contact angle (WCA) of 157.5° and a sliding angle (SA) of 2°. These films exhibit excellent antibacterial properties. When the content of ZIF-8 particles in the film is 300 mg·L-1, the antibacterial rate reaches 100% after 1 h of treatment. Thus, the ZIF-8 porous poly(vinylidene fluoride)-poly(methyl methacrylate) composite (ZPPP) film has potential application prospects in areas with high health and environmental requirements, such as cold chain transportation and public spaces.

Strengthened Poly(vinylidene fluoride)/Epoxidized Natural Rubber Blend by a Reactive Compatibilizer Based on an Amino Acid-Modified Fluorocarbon Elastomer

Strengthened Poly(vinylidene fluoride)/Epoxidized Natural Rubber Blend by a Reactive Compatibilizer Based on an Amino Acid-Modified Fluorocarbon Elastomer

Quenching induced modified nanoarchitectonics in the dielectric and energy storage behavior of poly (vinylidene fluoride)/Ba0.7Sr0.3TiO3 composites thick films

Quenching induced modified nanoarchitectonics in the dielectric and energy storage behavior of poly (vinylidene fluoride)/Ba0.7Sr0.3TiO3 composites thick films

Heart rate monitoring system based on piezoelectric poly(vinylidene fluoride-co-trifluoroethylene) composites with barium strontium titanate ceramic particles

A heart rate sensor device has been designed and developed based on a composite material based on poly(vinylidene fluoride – co – trifluoroethylene), P(VDF-TrFE) as polymer matrix and barium strontium titanate (BST) particles as ceramic fillers. The composite films were prepared by solvent casting varying the ceramic particles content between up to 40 wt%, allowing to tailor the dielectric and piezoelectric response. The morphology, polymer phase and thermal properties are independent of the ceramic filler content, whereas the dielectric constant increases significantly with increasing filler content, the largest dielectric constant, ε’ = 38 at 1 kHz, being obtained for the composite with 40 wt% of ceramic particles. Further, the highest piezoelectric response, also dependent on ceramic filler content, is |d33|= 29 pC/N, being obtained for the 10 wt% ceramic particle content film. It is also shown by piezoresponse force microscopy that higher ceramic particles are characterized by more stable ferroelectric domains. The composite has been successfully proved for its potential in heart rate monitoring applications, exhibiting high levels of precision as well as reliability. This work on heart rate sensing presents a material suitable for its incorporation into wearable gadgets, medical devices, and sports equipment, compatible with integration by printing technologies, enabling consumers to access immediate data relevant to their cardiovascular health.

Dual-functional fluorescence sensors based on 3D lanthanide metal–organic framework and its mixed matrix membrane

A new lanthanide metal–organic framework (Ln-MOF) {[Eu(DPB)(H2O)](Me2NH2+)}n (1) (H4DPB = (1,1′:3′,1′’-terphenyl)-3,3′’,5,5′’-tetracarboxylic acid）was synthesized under solvothermal conditions and presented a fascinating three-dimensional (3D) framework with 4,8-connected diamond topology, which were built from Eu3+ ions and tetra carboxylate groups. 1 showed strong red luminescence emission in the solid state at room temperature and exhibited good stability in different solvents. 1 could be used as a multi-responsive luminescent sensor for hemin and p-Nitrophenol (4-NP) with detection limits of 3.91 × 10−6 M and 1.98 × 10−4 mM, respectively. Moreover, using 1 as a filler and poly (vinylidene difluoride) (PVDF) as matrix, a mixed matrix membrane 1@PVDF was successfully prepared. 1@PVDF also exhibited fluorescence emission comparable to that of 1 and could be used for hemin and 4-NP sensing with good selectivity and remarkable recyclability.

Enhanced and copper concentration dependent virucidal effect against SARS-CoV-2 of electrospun poly(vinylidene difluoride) filter materials

Enhanced and copper concentration dependent virucidal effect against SARS-CoV-2 of electrospun poly(vinylidene difluoride) filter materials

Flexible piezoelectric energy-harvesting nanogenerator using supersonically sprayed polyvinylidene fluoride and iron oxide nanocubes

Soft wearable electronics are being applied as state-of-the-art self-powered devices based on piezoelectric nanogenerators (PENGs), which provide flexible energy harvesters and sustainable energy generators. We introduce a composite of poly(vinylidene fluoride) (PVDF) and Fe2O3 nanocube fillers coated via supersonic cold spraying to obtain substrate-free and flexible films for PENGs. The hydrothermally synthesized Fe2O3 nanocubes induce shear stress between Fe2O3 and PVDF during supersonic spraying. An optimized sample having 0.77g Fe2O3 in 1g PVDF produces a piezopotential of 25V and a short-circuit current of 70 μA. In addition, a maximum instantaneous power density of 44.4 μW·cm−2 is achieved at a load resistance of 1 MΩ. Tapping and bending tests for 1800 s confirm the consistent generation of piezopotentials of 25V and 1.5V, respectively. The developed Fe2O3/PVDF PENG can power several light-emitting diodes, thus showing promise as a device for sustainable power supply.

Effects of coagulant bath temperature toward separation performance and antifouling properties of PVDF/CA membranes for filtration of dyes

Phase inversion is used to prepare poly(vinylidene fluoride) (PVDF) microfiltration membranes by combining it with the hydrophilic polymer additive cellulose acetate (CA). For the filtration of methylene blue (MB) and acid yellow 17 (AY17), the effects of coagulant bath temperature (CBT) on the separation performance and antifouling properties are thoroughly investigated. SEM analysis shows that the membrane at higher CBT has a larger pore diameter than at lower CBT, resulting in differences in membrane surface hydrophilicity. It is found that the increase in surface hydrophilicity causes the permeability of PVDF/CA membranes to be higher at higher CBT than at lower CBT. Rejection values above 90% indicate that the membranes are more effective for MB separation at both lower and higher CBT. Otherwise, lower CBT provides better AC rejection than higher CBT. The Flux Recovery Ratio, which is higher at higher CBT, remains in the 75–95% range at lower CBT. As a result, lower CBT is better for membrane fouling resistance than higher CBT. In addition, the fouling observed at lower CBT is similar to the fouling observed at higher CBT, but lower CBT has a higher percentage of reversible fouling than higher CBT. The membranes with more reversible fouling are therefore easier to clean using the backwashing process. As a result, PVDF/CA membranes manufactured at lower CBT have better separation performance and antifouling characteristics than those manufactured at higher CBT.

Preparation of Three Component PVDF‐Bi4V2O11‐SDS Composites with Enhanced Dielectric and Electrical Properties

AbstractIn 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.

Enhanced Dielectric and Electric Properties of ZnFe2O4‐Poly(Vinylidene Fluoride) Composites by Employing Surface Hydroxylated ZnFe2O4 Nanoparticles

AbstractA 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.

Enhanced dielectric constant and concurrently suppressed dielectric loss of PVDF composites incorporating BaTiO3@SSCNT@SiO2 core@double-shell structured fillers

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 BaTiO3 (BT) as a core and silica (SiO2) as an outer shell were synthesized. As the thickness of the insulating shell is enough thin, the BT@SSCNT@SiO2/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 SiO2 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.

Development of flexible PVDF/ BaTiO3-MoS2 polymer nanocomposites for energy harvesting and gas sensing applications

The need for flexible and wearable devices is quite great in the modern era of advanced electronics and the Internet of Things (IoT). Here, we present a poly(vinylidene fluoride) (PVDF)/Barium Titanate–Molybdenum Disulfide (BaTiO3–MoS2) composite-based flexible piezoelectric nanogenerator (PENG) with an improved electroactive phase. The electroactive, β-phase of the PVDF is shown to increase with the addition of BaTiO3–MoS2 fillers as a result of the filler’s good interfacial interaction with the polymer matrix. The improved electroactive phase in the PVDF matrix was confirmed by the X-ray diffraction method and FTIR analysis of the composite films. The uniform dispersion of filler particles in the polymer matrix was confirmed by a scanning electron microscopy analysis. The developed piezoelectric nanogenerator device generated peak-to-peak output voltage of 4.9 V with a high dielectric constant of 22 and a low dielectric loss of 4.7. The fabricated gas sensor can perform at room temperature and exhibits good gas sensing performance toward the NH3 gas. It was found that, compared to all other samples, the composite PVDF/BaTiO3–MoS2 films had a high level of sensitivity. Additionally, the composite films showed response and recovery times of 11 and 17 s. The composite based on PVDF/BaTiO3–MoS2 is a suitable material for NH3 sensor applications.

Weak-Interaction Environment in a Composite Electrolyte Enabling Ultralong-Cycling High-Voltage Solid-State Lithium Batteries.

Poly(vinylidene fluoride) (PVDF)-based solid electrolytes with a Li salt-polymer-little residual solvent configuration are promising candidates for solid-state batteries. Herein, we clarify the microstructure of PVDF-based composite electrolyte at the atomic level and demonstrate that the Li+-interaction environment determines both interfacial stability and ion-transport capability. The polymer works as a "solid diluent" and the filler realizes a uniform solvent distribution. We propose a universal strategy of constructing a weak-interaction environment by replacing the conventional N,N-dimethylformamide (DMF) solvent with the designed 2,2,2-trifluoroacetamide (TFA). The lower Li+ binding energy of TFA forms abundant aggregates to generate inorganic-rich interphases for interfacial compatibility. The weaker interactions of TFA with PVDF and filler achieve high ionic conductivity (7.0 × 10-4 S cm-1) of the electrolyte. The solid-state Li||LiNi0.8Co0.1Mn0.1O2 cells stably cycle 4900 and 3000 times with cutoff voltages of 4.3 and 4.5 V, respectively, as well as deliver superior stability at -20 to 45 °C and a high energy density of 300 Wh kg-1 in pouch cells.

Synthesis of a Cu-Al bimetallic oxide @ PVDF composite membrane for the degradation of bisphenol a via peroxydisulfate activation: Performance and mechanism

The presence of environmental endocrine-disrupting compounds, such as bisphenol A (BPA), in aquatic environments poses a significant risk to both ecological integrity and human health. Although CuO has been reported as a catalyst for activating peroxydisulfate (PDS) to degrade BPA, it exhibits certain limitations, including low catalytic efficiency, aggregation, and challenges in terms of separation and reusability. In this study, we developed a composite poly (vinylidene fluoride) (PVDF)-based membrane incorporating Cu-Al bimetallic oxide (Cu-Al) to address these issues. Results revealed that when employing the 7 wt% Cu-Al @ PVDF composite membrane to activate 1 mM PDS, approximately 95.3 % of BPA was degraded within 60 min in static experiments. Furthermore, this composite membrane exhibited remarkable efficacy across a broad pH range (3–11) and demonstrated excellent resistance against diverse anionic species. The removal process is proposed to be dominated by electron transfer between the composite membrane, PDS, and BPA via a two-step mechanism: Firstly, electron-rich Cu sites and oxygen vacancies were formed in the composite membrane, facilitating PDS adsorption and electron transfer from Cu sites to PDS to form a ligand complex; subsequently, BPA was adsorbed by the membrane and acted as an electron donor to be oxidized by the ligand complex. As a result, this system showed remarkable selectivity for degrading electron-rich organic compounds with ionization potentials below 9.0 eV. Overall, this work successfully fabricated a catalytic membrane exhibiting efficient PDS activation capability along with selective oxidation performance and facile reusability, making it highly promising for wastewater treatment.

Fabrication of hydrophilic PVDF ultrafiltration membranes via thermally induced phase separation coupled with amphiphilic copolymer deposition

In this work, we propose a facile one-step method to fabricate poly(vinylidene fluoride) (PVDF) ultrafiltration hollow fiber membranes through coupled thermally induced phase separation (TIPS) and deposition of amphiphilic copolymer poly(styrene-co-maleic anhydride) (PSMA). A thorough examination of how the addition of PSMA influenced the membrane formation and performance was conducted. The mechanism behind the synergistic effect between TIPS process and deposition of PSMA on the membrane surface was discussed in detail. The difference in the phase separation behavior of PVDF and PSMA during membrane preparation caused the deposition of PSMA forming a hydrophilic layer on the PVDF porous structure without altering the membrane bulk structure. The enrichment of PSMA in membrane outer surface not only improved the hydrophilicity of the membrane, but also effectively reduced the membrane pore size, while maintaining the overall bulk porosity. PSMA deposition resulted in enhanced pure water flux and BSA rejection, effectively overcoming the traditional trade-off between permeability and selectivity. This straightforward approach of blending suitable amphiphilic copolymers into the polymer solution exhibited significant potential for the rapid and large-scale preparation of hydrophilic PVDF-based ultrafiltration membranes in the TIPS process.