Polyvinylidene Fluoride Film Research Articles

Relaxation processes in the oriented polyvinylidene fluoride films with various crystalline phase composition

Relaxation processes in the oriented polyvinylidene fluoride films with various crystalline phase composition

Enhancing energy storage properties via controlled insulation properties of PVDF-based polymer capacitors

In the realm of energy storage and electrical insulation, this study illuminates the innovative fabrication and consequent properties of polyvinylidene fluoride (PVDF) and polyethylene glycol (PEG800) blend films, synthesized via the casting method. The essence of this research lies in the integration of PEG800 into the PVDF matrix, a strategic move that significantly bolsters the insulation capabilities of the resulting composite, underscored by a dramatic decrease in leakage current from 2.61E-7 A to 3.50E-9 A at an electric field of 50 MV/m. Notably, at an optimal PEG800 mass fraction of 30 %, the composite film unveils an extraordinary energy storage density of 34.6 J/cm3 under the formidable electric field of 650 MV/m. This study not only shows cases the superior energy storage and rapid charge-discharge characteristics, particularly with a discharge time (t0.9) of 66 ns of the 70PVDF/30PEG800 film, but also underscores the potential of such blend films in revolutionizing the design and functionality of polymer film capacitors, marking a significant stride towards sustainable and efficient energy storage solutions.

Investigation of Dielectric and Piezoelectric Properties of Polyvinylidene Fluoride Films Reinforced with Anatase Phase Titanium Dioxide for Pressure Sensing

Investigation of Dielectric and Piezoelectric Properties of Polyvinylidene Fluoride Films Reinforced with Anatase Phase Titanium Dioxide for Pressure Sensing

Preparation and study of polyvinylidene fluoride film with high UV aging resistance

Abstract Polyvinylidene fluoride materials were widely used in the preparation of solar panel films due to their excellent weather resistance and heat resistance. In this work, Polyvinylidene fluoride films with UV absorbers (PF/UV films) were prepared by customized extrusion equipment. The properties of these films were demonstrated with a scanning electron microscope (SEM), water contact angle (WCA), thermogravimetric analyzer (TGA), differential scanning calorimetry (DSC), and tensile strength tester. Furthermore, the SEM observation suggested that PF/UV films had smooth surfaces without significant defects. The WCA results illustrated that PF/UV films had better hydrophobicity than polyvinylidene fluoride films. The TGA and DSC curves indicated that the initial decomposition temperature and the melting temperature of the PF/UV film were 365.1°C and 169.2°C, respectively. Furthermore, the results of UV transmittance indicated that the UV aging resistances of PF/UV film were higher than that of polyvinylidene fluoride film.

A Review on properties and applications of Polyvinylidene fluoride (PVDF)and metal oxide nanocomposites thin films.

A Review on properties and applications of Polyvinylidene fluoride (PVDF)and metal oxide nanocomposites thin films.

Insights and perspectives on PVDF/MgO NCs films: Structural and optical properties for optoelectronic device applications

In the current investigation, pure polyvinylidene fluoride (PVDF) and PVDF-MgO nanocomposite (NC) thin films are fabricated via solvent casting method using PVDF as a polymer matrix with different proportions of magnesium oxide (MgO) (0.5–2 wt%). The structural, morphological and optical properties of the prepared polymer NCs are studied by using XRD, FTIR, SEM, Raman and UV–Vis spectroscopy techniques. The α and β phases are detected in XRD measurements. MgO powder peaks are in good agreement with the reported literatures. The average crystallite size, lattice strain, and dislocation density of the prepared thin films are estimted by using Williamson-Hall (W-H) plot. SEM micrographs reveals the fluorine-containing carbon chain network that forms the spherulite and fiber-like structure in the PVDF/MgO NCs films. The Raman and FTIR spectra of PVDF/MgO and pure PVDF films are also evaluated. UV–Vis spectroscopy is used to examine the absorbance, transmittance, and reflectance spectra of pure PVDF and PVDF/MgO NCs thin films. The dipole polarization interaction causes the absorption coefficient, direct band gap, indirect band gap, optical activation energy, and skin depth of pure PVDF and PVDF/MgO thin films to decrease, whereas increasing the dielectric constant at high frequency value, refractive index, loss, optical conductivity, and dielectric constant per effective mass of NCs films. Optical dispersion parameters are estimated by the single oscillator model. The obtained results can be employed in the possible applications in supercapacitors. The method used for the preparation of thin films are inexpensive and eco-friendly.

Impact force measurement by in-plane piezoelectricity of polyvinylidene fluoride films

This manuscript provides a new idea to solve the problems related to measurement of impact force wave especially in the situation with a strong environment noise by utilizing the polyvinylidene fluoride (PVDF) film instead of strain gauge. According to our experimental results, an extremely high ratio between output signal and noise in environment (SN ratio) is realized even the infrequently employed in-plane piezoelectricity of film is utilized. Instead of piezoelectricity in thickness direction, attachment of film on Hopkinson pressure bar based on in-plane piezoelectricity could help us to avoid the influence from separation of Hopkinson pressure bar on measurement result. We could conclude that a more precise measurement could be realized by a short film rather than long one even though the short film shows a relative lower output signal. However, the output signal could be amplified by increasing its width. Besides, comparing with the use of strain gauge, broader bandwidth of film measurement is discovered. In the situation where the duration of impact force wave is extremely short, high accuracy measurement should be realized by PVDF film rather than strain gauge.

Characterization of Catheter-Type Tactile Sensor Using Polyvinylidene Fluoride (PVDF) Film

To enable quantitative palpation in vivo, we previously developed a catheter-type tactile sensor with an outer diameter of 2 mm composed of a polyvinylidene fluoride (PVDF) film for minimally invasive surgery. However, our previous studies did not evaluate the effect of the PVDF film shape on the sensor output. In this study, we fabricated three types of prototype sensors with different PVDF film shapes and sizes using a simple cutting method. One of the films had the same shape as that used in one of our previous studies. We also prepared two types of PVDF film with a wide base and a narrow tip because we assumed that the deformation of the sensor gradually decreases from the root to the tip, similar to the first mode of the natural frequency. We evaluated the frequency response of the proposed sensors by vibrating the sensor tip and compared the results with the theoretical values. It was confirmed that the sensor output increased with PVDF film size. Although this tendency was observed for both the measured and theoretical values, the measured values were smaller than the theoretical values. Moreover, the effect of film size was larger than that of film shape. Improvements in the sensor structure and the theoretical equation and better evaluation methods are required in order to optimize the film shape and size.

Ferroelectric, flexoelectric and photothermal coupling in PVDF-based composites for flexible photoelectric sensors.

A ferroelectric polyvinylidene fluoride (PVDF) film with excellent flexibility possesses great potential for photodetection and wearable devices. However, the relatively weak photo-absorption and the consequent small photocurrent limit its photofunctional properties. Herein, we embedded a strongly visible-light active material system, 0.5Ba(Zr0.08Ti0.8Mn0.12)O3-0.5(Ba0.7Ca0.3)TiO3 (BZTM-BCT) loaded with Ag and Au nanoparticles, into a PVDF film, which demonstrates a significantly higher photovoltaic response in the whole visible light range with a β-phase content of over 90%. In a state of "bending + poling", the PVDF/BZTM-BCT:Au film presents an optimal response for photoelectric properties by exhibiting a photocurrent that is 57 times higher than that of a pure PVDF film when illuminated with 405 nm LED light at 100 mW cm-2. Photoexcitation and thermal excitation jointly contribute to the generation of free carriers, while the flexoelectric and ferroelectric coupling electric field provides a greater driving force for carrier separation and transport. More interestingly, composite film-based photoelectric sensors can simultaneously respond to light and the movement and deformation of contacted things, indicating its potential in versatile applications. Overall, this work puts forward a new route for designing new flexible multifunctional photoelectric devices.

Preparation and characterization of oxygen‐functionalized graphene‐doped polyvinylidene fluoride ultrafiltration membranes

AbstractTo separate the oil/water mixtures, polyvinylidene fluoride (PVDF) nanofiber mats were produced using electrospinning. Additionally, PVDF films were made using the solvent evaporation method, and the effectiveness of their separation was evaluated against that of nanofiber mats. By choosing oxygen‐functionalized graphene (with HNO3) as a nano reinforcement, the hydrophobic properties of the PVDF materials made using both techniques were transformed into hydrophilic ones. It has been determined how the characteristics of the solution (viscosity, conductivity, molecular weight, surface tension, and contact angle) relate to the diameter of the nanofiber. Fourier transform infrared spectroscopy‐attenuated total reflection (FT‐IR/ATR), x‐rays diffraction (XRD), scanning electron microscope, thermogravimetric analyses (TGA)/DTG, and differential scanning calorimetric (DSC) have been used to study the chemical and crystal structures, morphology, and thermal behavior of PVDF materials. The addition of oxygen‐functionalized graphene was found to cause a peak in the PVDF composites' FT‐IR/ATR spectrum, roughly in the wavenumber 1400 cm−1, which was identified as the C‐OH bending vibration. Together with the shift in peak strengths, the lack of a discernible shift in the PVDF peak location in the XRD patterns indicates that the addition of oxygen‐functionalized graphene has caused a phase transition in the PVDF in the semi‐crystal structure. Surface hydrophobicity has also been measured using contact angle measurements. The addition of oxygen‐functionalized graphene has been seen to decrease the PVDF's contact angle, resulting in the development of a hydrophilic characteristic. These PVDF‐based materials' oil/water separation capabilities have also been evaluated. PVDF composite films were not as effective as PVDF nanofiber mats with oxygen‐functionalized graphene in the studies to separate the oil/water mixtures. The permeate flux value was determined to be 240 Lm−2 h−1, and the oil/water separation efficiency of nanofibers containing 10% (m/m) PVDF534000 combined with oxygen‐functional graphene was found to be 99%.

Modelling of energy harvesting with bendable concrete and surface-mounted PVDF

Polyvinyl alcohol fiber reinforced engineered cementitious composite (ECC) using piezoelectric polymer film has attracted significant interest due to its energy harvesting potential. This work provides a theoretical model for evaluating the energy harvesting of bendable ECC using surface-mounted polyvinylidene fluoride (PVDF). In the mechanical part, concrete damage plasticity model based on the explicit dynamic analysis was utilized to simulate the dynamic flexural behavior of ECC beam under different dynamic loading rates. The mechanism of force transfer through the bond layer between the PVDF film and ECC specimen was simulated by a surface-surface sliding friction model wherein the PVDF film was simplified as shell element to reduce computational cost. Then, the electromechanical behavior of the piezoelectric film was simulated by a piezoelectric finite element model. A simplified model was also given for a quick calculation. The theoretical model was verified with the experimentally measured mechanical and electrical results from the literature. Finally, a parametric analysis of the effects of electromechanical parameters on the efficiency of energy harvesting was performed. The verified theoretical model can provide a useful tool for design and optimization of cementitious composite systems for energy harvesting application.

Solar-driven hydrovoltaic-pyroelectric hybrid generator for efficiently harvesting water transformation energy

Manipulation of water for power generation has garnered significant research interest as it is renewable, sustainable, and a spontaneous form of energy production. However, energy conversion efficiency has remained constrained, primarily attributed to the slow evaporation rates of water and limited energy recovery strategies. Herein, we demonstrate a two-pronged hybrid water transformation energy harvester that strategically integrates solar-thermal effects with pyroelectric effects to boost water transformation and its associated energy extraction. The core of our unique ensemble consists of two layers: the upper layer features a composite film comprising carbon black (CB) and polyvinylidene fluoride (PVDF) coated onto bamboo fibers (CB/PVDF@BFP), which realizes solar-thermal and hydrovoltaic effects owing to the excellent solar-thermal and electrical activities of CB while the bottom layer is PVDF film to simultaneously generate pyroelectricity. Notably, the optimized CB/PVDF@BFP achieves a maximal temperature of ∼78 ℃ and an open-circuit voltage (VOC) and a short-circuit current (ISC) of 0.33 V and 1.6 μA, respectively. Consequently, we achieved a maximal output power density of 64 μW/m2 under one sun (25 ℃), surpassing the output under dark conditions by ∼92 %, and exceeding most similar designs. Moreover, the CB/PVDF@BFP film exhibits a maximal oscillation of ∼0.5 ℃/s and an evaporation rate of 1.44 kg·m−2·h−1 under optimized conditions, owing to the strategic inclusion of hydrophilic BFP. Concurrently, our ensemble also generates a maximum VOC, ISC and output power density of pyroelectricity of ∼80 V, 0.4 μA, and 7.4 mW/m2 (∼25.9-fold higher than the dark state), which is > ∼3.9-time higher than the similar reports, respectively. As proof of concept, our hybrid design can successfully power various household electronic devices (such as LED lights, electronic watches etc.) by storing the harvested energy into capacitors, thus showcasing its potential for practical applications. Our ensemble not only demonstrates remarkable performance but also lays the foundation for innovative concepts in the development of emerging hybrid micro/nano-generators, offering an avenue for harnessing ubiquitous ambient energy.

Optical band gap engineering and comparison of conductivity of CaTiO3 and LiNbO3 doped PVDF films

This study explores the impact of CaTiO3 and LiNbO3 crystals on the optical and dielectric properties of polyvinylidene fluoride (PVDF) films. Our investigation employs UV–Visible Spectroscopy to characterize the n-π* C-F related electronic transition within the PVDF matrix. We find that CaTiO3 crystals significantly decrease the composite’s band gap and dielectric properties, enhancing its electronic and optical attributes. Conversely, LiNbO3 crystals increase the band gap energy. These variations align with observed DC conductivity changes, suggesting novel functionalities for optoelectronic, sensing, and energy storage applications.

Multi-Scale MXene/Silver Nanowire Composite Foams with Double Conductive Networks for Multifunctional Integration.

With the onset of the 5G era, wearable flexible electronic devices have developed rapidly and gradually entered the daily life of people. However, the vast majority of research focuses on the integration of functions and performance improvement, while ignoring electromagnetic hazards caused by devices. Herein, the 3D double conductive networks are constructed through a repetitive vacuum-assisted dip-coating technique to decorate the 2D MXene and 1D silver nanowires on the melamine foam. Benefiting from the unique porous structure and multi-scale interconnected frame, the resultant composite foam exhibited high electrical conductivity, low density, superb electromagnetic interference shielding (48.32dB), and Joule heating performance (up to 90.8°C under 0.8V). Furthermore, a single-electrode triboelectric nanogenerator (TENG) with powerful energy harvesting capability is assembled by combining the composite foam with an ultra-thin Ecoflex film and a polyvinylidene fluoride film. Simultaneously, the foam-based TENG can also be considered a reliable wearable sensor for monitoring activity patterns in different parts of the human body. The versatility and scalable manufacturing of high-performance composite foams will provide new design ideas for the development of next-generation flexible wearable devices.

Inducing Polar Phase in Poly(Vinylidene Fluoride) with a Molecular Ferroelectric Copper(II) Complex for Piezoelectric Energy Harvesting

AbstractPiezoelectric nanogenerators (PENGs), the current pathway to sustainable energy harvesting, are mostly comprised of bulk oxide ceramics which are toxic, rigid, and costly to synthesize. A suitable alternative to them is flexible polar polymers like polyvinylidene fluoride (PVDF), but stabilizing its polar phase is also a daunting task. all these aforementioned issues by employing a biocompatible have been solved, above‐room‐temperature (Tc > 390 K) ferroelectric discrete molecular complex [Cu(L‐His)(bpy)]ClO4.1.5H2O (Cu‐FE) which is not only suitable for piezoelectric energy harvesting due to its large values of piezoelectric co‐efficient (d33 = 17 pm V−1) but also is capable of imparting polar β‐phase in PVDF via hydrogen bonding interactions under mild condition (60 °C). Among the PENG devices prepared with the composite films of PVDF and various weight % (w/V) compositions of Cu‐FE, the highest output voltage of 8 V (peak to peak) has been obtained, a power density of 4 µW cm−2, and an output current of 3 µA from the 1 wt.% composite film. The fabricated PENG device also exhibits swift capacitor charging in 40 s, and acts as an excellent pressure sensor, with exceptional sensitivity to low pressures (7 kPa), giving an output of 0.4 V.

Experimental study of taper shape bistable beam for improved vibration energy harvesting

Unwanted vibrations cause discomfort and affect the accuracy of the machinery. Vibrations of low frequency (<30 Hz) are usually inutile. Various researchers focus on harvesting and enhancing energy output through low-frequency vibrations. This paper focuses on improving energy harvesting from low-frequency vibration sources through taper shape (TAP) bistable beam fabricated using thin Piezoelectric Polyvinylidene fluoride (PVDF) film sandwiched between thin copper and aluminium films on both sides. Voltage power output through a PVDF film depends on the film’s strain distribution; hence, in this study, five different beam designs are studied for strain distribution through the ANSYS workbench. Further, an experimental harmonic analysis study for voltage output is performed on rectangular beam (RECT) and TAP beam for both straight and bistable configuration using three different harmonic input conditions, which concluded that the voltage output for the TAP beam is much more than that of the RECT beam, with a much more significant voltage output increase in bistable conditions for all three harmonic input conditions.

Investigating the Influence of Frequency on Piezo-dynamics of Polyvinylidene Fluoride (PVDF) Films Embedded in Confined Geomaterials

Investigating the Influence of Frequency on Piezo-dynamics of Polyvinylidene Fluoride (PVDF) Films Embedded in Confined Geomaterials

Re-usable Cd0.9Zn0.1S-ZnO@C/PVDF piezo-photocatalytic film with exceptional hydrogen evolution capability triggered by the synergetic advantages of piezoelectricity and S-Scheme heterojunction

Piezoelectric materials have advantages of fine-tuning photocatalytic performance through harvesting mechanical energy and open a new avenue in facilitating green catalytic reaction. Herein, polyvinylidene fluoride (PVDF), a flexible piezoelectric material, was introduced to synthesize a novel Cd0.9Zn0.1S-ZnO@C/PVDF (CZS-ZO@C/PVDF) piezo-photocatalytic film by spin coating and immersion phase conversion method. Benefiting from the piezoelectricity of PVDF and the internal electric field (IEF) of CZS-ZO@C Step-scheme (S-Scheme) heterojunction, CZS-ZO@C/PVDF was able to induce a hydrogen generation rate of 34.9 mmol g−1 h−1 activated by ultrasound and visible light (U-L), which is ∼17.5 times of Cd0.9Zn0.1S/PVDF (CZS/PVDF) and ∼7.4 times of the photocatalysis rate activated by visible light only (L). Piezoelectric measurements and COMSOL simulation illustrated the excellent piezoelectricity of CZS-ZO@C/PVDF film, which exhibits a piezoelectric coefficient (d33) of 9.9 pm V−1 and a piezoelectric potential of 874 mV (under 0.5 MPa). The reaction mechanism for the exceptional piezo-photocatalytic performance was finally disclosed through density functional theory (DFT) calculation and electrochemical tests. This study enriches the application scope of piezoelectric materials in sustainable energy catalysis and provides a new direction to develop efficient piezoelectric photocatalysts.

Kirigami-inspired, three-dimensional piezoelectric pressure sensors assembled by compressive buckling

Piezoelectric sensors whose sensing performances can be flexibly regulated hold significant promise for efficient signal-acquisition applications in the healthcare field. The existing methods for regulating the properties of polyvinylidene fluoride (PVDF) films mainly include material modification and structural design. Compared to material modification, which has a long test period and an unstable preparation process, structural design is a more efficient method. The irigami structure combined with compressive buckling can endow the flexible film with rich macrostructural features. Here, a method is fabricated to modulate the sensing performance by employing distinct 3D structures and encapsulation materials with varying Young’s moduli. The relationship among the aspect ratio (α), pattern factor (η), elastic modulus of encapsulation materials, and equivalent stiffness is obtained by finite element simulation, which provides theoretical guidance for the design of the 2D precursor and the selection of encapsulation materials. In the demonstration applications, the sensor accurately captures pulse waveforms in multiple parts of the human body and is employed for the pressure monitoring of different parts of the sole under various posture states. This method of structure design is efficient, and the preparation process is convenient, providing a strategy for the performance control of piezoelectric pressure sensors.

Fabrication of PVDF/TiO2@CQDs photocatalytic films by ink-jet printing for dye degradation under visible light

PVDF/TiO2@CQDs hybrid photocatalytic thin films were prepared by ink-jet printing. The printing ink was prepared with the TiO2, TiO2(s)@CQDs (surface composite), and TiO2(i)@CQDs (situ doping) nanoparticles as precursors, respectively. Compared to TiO2(s)@CQDs, TiO2(i)@CQDs has a smaller particle size (about 10.01 nm) and a narrower particle size distribution (6∼14 nm), which can improve the photocatalytic effect while avoiding nozzle clogging. The PVDF/TiO2(i)@CQDs hybrid film exhibited a high degradation efficiency (η) of 93.71 % for Rhodamine B (RhB) within 150 min under visible light with a catalyst load of only 0.49 wt%. The reaction rate constant (ks) of the PVDF/TiO2(i)@CQDs film was about 4.3 times higher than that of the PVDF/TiO2(s)@CQDs film. The small particle size of this S-scheme TiO2(i)@CQDs heterostructure nanoparticle and the more effective contact interface formed between TiO2 and carbon quantum dots (CQDs) further facilitated electron transfer and enhanced photoactivity. The firmly immobilized catalysts on the Polyvinylidene fluoride (PVDF) film substrate through Ti-F coordination bonds ensured the reusability and stability of the photocatalytic film (the η of RhB still reached 88.05 % after 10 consecutive cycles). This work provides a new strategy for the application of ink-jet printing technology in photocatalysis.