Polyvinylidene Fluoride Film Research Articles

Supersonically Sprayed Cobalt Titanate and PVDF for Flexible Piezoelectric Nanogenerators

Piezoelectric nanogenerators (PENGs) are the core components of self-powered devices used in sensors, ecofriendly wearable gadgets, and biomedical implants. This study introduces and demonstrates a flexible PENG with supersonically cold-sprayed films of cobalt titanate (CTO) and polyvinylidene fluoride (PVDF). An electrically poled PENG produces a maximum output voltage of 34.8 V under a tapping force of 20 N, whereas a CTO/PVDF-based PENG exhibits 25.4 V across a loading resistance ( R L ) of 50 MΩ and generates a short-circuit current of 30 μA at 0.1 MΩ. Furthermore, the maximum power density is 25 μW·cm-2 at R L = 0.6 MΩ. Cyclic tapping and bending test results show that open-circuit voltages (Voc) of 25.4 and 5.8 V are produced under the tapping cycle of N tap = 4200 and bending cycle of N bend = 750 , respectively, confirming the mechanical durability of the PENG. Thus, the potential of CTO/PVDF films for use in PENGs with various functionalities can be confirmed based on the V oc values generated from bending, mobile tapping, walking, and lifting movements.

Design and analysis of a flexible hydrophone based on PVDF with aluminum film substrate and PDMS encapsulation

Unmanned underwater vehicles (UUVs) need hydrophones for underwater acoustic sensing. However, previous hydrophones were rigid in shape and unable to realize conformal installation. In this paper, a flexible hydrophone with great installation adaptability was presented. Polyvinylidene fluoride (PVDF) piezoelectric film was applied as the transducing material. A flexible aluminum film was selected as the substrate. These two films were sandwiched by polydimethylsiloxane (PDMS) layers. Finite element simulation revealed that the sensitivity and bandwidth of the hydrophone were enhanced by using the aluminum film substrate. The sensing performance improvement was ascribed to the suppressed in-plane stress of the PVDF film. Prototypes were fabricated and tested. The fabricated hydrophone exhibited a sensitivity of −211 dB (ref. 1 V/μPa) at 500 Hz. It owned a 20–500 Hz working frequency range and an omnidirectional pattern. Besides, the sensitivity difference caused by shape changes was within 2.3 dB. Furthermore, the hydrophone showed good waterproofing ability.

Effect of ferroelectric filler nanoarchitectonics on the electrical and mechanical properties of the nanocomposite thick films of polyvinylidene fluoride and lanthanum-doped lead zirconate titanate in 0–3 connectivity

Effect of ferroelectric filler nanoarchitectonics on the electrical and mechanical properties of the nanocomposite thick films of polyvinylidene fluoride and lanthanum-doped lead zirconate titanate in 0–3 connectivity

Effect of Composition and Surface Microstructure in Self-Polarized Ferroelectric Polymer Films on the Magnitude of the Surface Potential.

The values of the surface potentials of two sides of films of polyvinylidene fluoride, and its copolymers with tetrafluoroethylene and hexafluoropropylene, were measured by the Kelvin probe method. The microstructures of the chains in the surfaces on these sides were evaluated by ATR IR spectroscopy. It was found that the observed surface potentials differed in the studied films. Simultaneously, it was observed from the IR spectroscopy data that the microstructures of the chains on both sides of the films also differed. It is concluded that the formation of the surface potential in (self-polarized) ferroelectric polymers is controlled by the microstructure of the surface layer. The reasons for the formation of a different microstructure on both sides of the films are suggested on the basis of the general regularities of structure formation in flexible-chain crystallizing polymers.

Simulating study of cochlear sensors based on PVDF organic polymer materials

Cochlear implant is an effective choice to recover hearing for patients with sensorineural deafness. With the development of society, people’s demand for cochlear implants in all aspects is increasing. Polyvinylidene fluoride (PVDF) film is a kind of high polymer with excellent properties, which has broad application prospects in the field of cochlear implant. This article uses COMSOL software to simulate PVDF films and explore the size effect on the sensor performance. The simulation results show that the eigenfrequency is linearly related to height, meanwhile the vibration mode and electric potential also vary with height. The cochlear sensor is simulated in the range of human ear-sensitive hearing frequency, and the cochlear sensor has excellent piezoelectric properties. The cochlear sensor obtained after simulation can help patients with sensorineural deafness to better identify their hearing.

Wearable Triboelectric Nanogenerators Based on Printed Polyvinylidene Fluoride Films Incorporated with Cobalt‐Based Metal–Organic Framework for Self‐Powered Mobile Electronics

In this study, wearable triboelectric nanogenerators comprising bar‐printed polyvinylidene fluoride (PVDF) films incorporated with cobalt‐based metal–organic framework (Co‐MOF) were developed. The enhanced output performance of the TENGs was attributed to the phase transition of PVDF from α‐crystals to β‐crystals, as facilitated by the incorporation of the MOF. The synthesis conditions, including metal ion, concentration, and particle size of the MOF, were optimized to increase open‐circuit voltage (VOC) and open‐circuit current (ISC) of PVDF‐based TENGs. In addition to high operational stability, mechanical robustness, and long‐term reliability, the developed TENG consisting of PVDF incorporated with Co‐MOF (Co‐MOF@PVDF) achieved a VOC of 194 V and an ISC of 18.8 μA. Furthermore, the feasibility of self‐powered mobile electronics was demonstrated by integrating the developed wearable TENG with rectifier and control units to power a global positioning system (GPS) device. The local position of the user in real‐time through GPS was displayed on a mobile interface, powered by the battery charged through friction‐induced electricity generation.

Preparation and application of MWCNT-MoO3/ZnO ternary hybrid immobilized PVDF hybrid film photocatalyst

This study presents a novel method for immobilizing hybrid catalysts on polyvinylidene fluoride (PVDF) polymeric membranes for solid–liquid separation. A multi-walled carbon nanotube (MWCNT) doped with α-MoO3/ZnO photocatalyst (MWCNT-MoO3/ZnO) was prepared using an ultrasonic-assisted hydrothermal method. The photocatalysts were immobilized into PVDF membranes to prepare PVDF/MWCNT-MoO3/ZnO (IM-C3) via the phase inversion method and evaluated using methylene blue (MB) dye. The bandgap energy and e- - h+ separation potential of the materials was validated using UV–vis diffuse reflectance spectroscopy (UV–vis DRS) and photoluminescence (PL) spectroscopy. The UV–vis DRS results confirmed that the band gap energy of powdered photocatalysts decreased with increasing amounts of MWCNT as C1 (2.7 eV), C2 (2.6 eV), and C3 (2.4 eV). X-ray diffraction (XRD), and field emission scanning electron microscopy (FESEM) validate the structure and morphology of the photocatalysts. The EDX spectra confirm impurity-free samples. The Braeuer-Emmett-Teller (BET) method was used to determine the surface area (m2/g) and porosity of the MWCNT-MoO3/ZnO powdered photocatalyst, which exhibits a mainly mesoporous nature. The specific surface area of C3 was approximately 87.4 m2/g, which is greater than that of C2 and C1 (47.0 m2/g and 18 m2/g, respectively). The atomic force microscopy (AFM) and water contact analysis (WCA) showed that the surface roughness and hydrophilicity of the PVDF film were enhanced upon immobilization of the C3 photocatalyst. This resulted in a better interaction between the MB dye and the prepared IM-C3 hybrid film photocatalyst, thus making it capable of degrading 96 % of the MB dye within 120 min under visible light irradiation. The impact of the operating parameters of the hybrid film photocatalysts, such as the number of films, solution pH, MB concentration, radical scavenger, and recyclability studies, has been prioritized. The degradation percentage decreased as the initial concentration of MB (10–20 mg/L) increased but increased as the number of films increased. The superoxide radical (.O2–) and hydroxyl radical (OH.), were the dominant reactive species for the degradation of MB under visible light irradiation. The IM-C3 film can be reused up to five times without any kind of chemical treatment and without losing its stability or effectiveness.

Toward the development of a new smart composite structure based on piezoelectric polymer and flax fiber materials: Manufacturing and experimental characterization

Although technologies and processes for creating smart composite structures have been established, significant limitations still necessitate additional research to overcome. Indeed, numerous studies have highlighted the challenges of embedding active elements, often leading to compromises in the structural integrity of smart composite materials. In contrast, this study introduces a novel perspective, offering innovative insights and valuable contributions to the existing knowledge. The primary contribution of this study lies in addressing the critical need for the seamless integration of active materials within composite structures. To demonstrate this, our study considers the potential integration of Polyvinylidene Fluoride (PVDF), a polymer-based piezoelectric material, with pre-impregnated unidirectional flax fibers to produce a smart composite structure. The consolidation molding process was adopted to manufacture the smart composite samples for investigations. Experimental analysis were then considered to evaluate the influence of the embedded PVDF film on the mechanical performance of the structure and to assess the resulting functional properties. X-ray micro-computed tomography and an additional strength-of-material test approach, Interlaminar Shear Strength (ILSS), were performed to explore the impact of the insertion on the integrity of the laminate structure. On the other hand, we conducted vibration tests to assess the electromechanical properties. The tomography results reveal void elimination in the edges of the active material insert, which could be attributed to the choice of thin film materials. Moreover, the ILSS results highlight the minimal impact of PVDF material on mechanical performance, showcasing a mere 0.69% degradation of the material strength. These results are comparable to the recently reported works but with an appreciable margin of improvement. The vibration test response demonstrates the ability of the embedded piezoelectric material to generate voltage, which validates our integration procedure. The smart composite material’s sensitivity to ambient vibrations and its power generation potential show promise for sensing and energy harvesting.

Photothermal insulation mechanism of submicron ITO hollow particles in PVDF film

In this study, submicron Sn[Formula: see text]-doped In2O3 hollow particles (indium-tin oxide (ITO)) with a lyrium shell-like surface were synthesized via solvothermal method. The appropriate addition of these particles into polyvinylidene fluoride (PVDF) films exhibits high visible light transmission and effective UV/IR blocking properties, surpassing those of ITO nanoparticles. This can be attributed to the reduced absorption of UV/IR radiation by the hollow ITO particles, as well as their higher diffuse reflectivity and thermal insulation.

High performance flexible PVDF film pressure sensor fabricated by femtosecond laser

Flexible pressure sensors have shown great potential for applications in detection and medical fields due to their unique piezoelectricity and high sensitivity. In this paper, micro-nano-perforated structures with different periods and diameters are fabricated on the polyester (PET) films by femtosecond laser direct writing (FsLDW), and then the perforated structures are embossed on polyvinylidene fluoride (PVDF) films to form sensors with circular truncated cone (CTC) structures. The effect of period and diameter on the sensitivity of the sensor is studied numerically and experimentally. The results show that the high sensitivity of 8.98 mV/KPa can be achieved in a PVDF film pressure sensor with a period of 50 μm and a diameter of 30 μm, which is about 10.9 times that of the structureless sensor. This work not only provide a fast fabricated method for the pressure sensor based on the femtosecond laser and hot embossing, but also has potential applications in the detection of the micro-signals.

3D Printing of MXene‐Enhanced Ferroelectric Polymer for Ultrastable Zinc Anodes

AbstractZinc (Zn) metal anodes of aqueous zinc‐ion batteries (AZIBs) have attracted significant attention due to their high theoretical capacities, low redox potentials, and low cost. However, uncontrollable dendrite formation and side reactions can result in limited reversible cycling and quick failure of the batteries. Herein, a polyvinylidene fluoride (PVDF)‐based protection layer (PVDF‐MXene) with high β‐phase content is built by the 3D printing method. The synergistic effect attributed to the 3D printing approach and MXene nanosheets contributes to phase transition of the PVDF polymer chains from α‐phase to β‐phase, improving the ferroelectric properties of the printed PVDF films. Such a protection layer can manipulate the concentration distribution of zinc ions and enable the uniform growth of zinc plates. As a result, symmetrical zinc batteries using such anodes (PVDF‐MXene‐Zn) exhibit reversible Zn plating/stripping with low voltage hysteresis at 1.0 mA cm−2, 1.0 mAh cm−2 for over 4200 h, and a high‐rate capability up to 10 mA cm−2. When assembled with MnO2 and activated carbon, the resulting Zn‐MnO2 battery and zinc‐ion capacitor exhibited significantly enhanced cycling stability. The proposed strategy in this study provides a novel strategy for the protection of the zinc anode, thus promoting the practical application of ZIBs.

Characterization of dynamic confinement response of potting materials at different strain rates and temperatures

A Kolsky compression bar was modified with an instrumented confining tube for characterizing dynamic confinement response of materials at various strain rates. A thin film polyvinylidene fluoride (PVDF) force transducer was designed and integrated to the confining tube for direct in-situ measurement of confining pressure when the specimen is subjected to dynamic axial compressive load such that the mean stress-volumetric strain response of the specimen material is able to be determined. An environmental chamber was also implemented to the Kolsky compression bar for characterizing dynamic confinement response of materials at different environmental temperatures. After careful calibration of the instrumental confining tube, five different potting materials (EPON 828, EPON 828 filled with glass microballoons (GMBs), Sylgard 184, Sylgard 184 filled with GMBs, and expanded polystyrene (EPS) foam) were characterized with the modified Kolsky compression bar at different strain rates and environment temperatures. The effects of strain rate and temperature on the mean stress-volumetric strain response were determined for all five potting materials. Experimental uncertainties were also presented.

Beta-phase transformation of polyvinylidene fluoride with supersonically sprayed ZnSnO3 cuboids for flexible piezoelectric nanogenerators

Flexible self-powered electromechanical devices, such as piezoelectric nanogenerators (PENGs), which are used in wearable and implantable devices, are emerging as state-of-the-art clean energy sources. In this study, a scalable supersonic spraying technique was used to prepare flexible piezocomposite films of polyvinylidene fluoride (PVDF) and hydrothermally synthesized ZnSnO3 (ZSO) cubes for PENGs. Raman spectra confirmed that the transformation of the α-phase of PVDF to its β-phase was induced by the shear stress generated between the ZSO particles and PVDF polymer during supersonic spraying. The optimized sample comprising 0.43 g of ZSO cubes and 1 g of PVDF produced a maximum piezopotential of 41.5 V and a short-circuit current, Isc, of 52.5 μA. A maximum power density of 50.6 μW cm−2 was obtained at a loading resistance of 0.4 MΩ, which matched the impedance of the PENG. Long-term tapping and bending cycles of Ntap = 4200 and Nbend = 600 yielded piezopotentials of 40.5 and 1.7 V, respectively. In addition, electrical poling for 2 h increased the piezopotential to 52 V owing to the alignment of the ferroelectric dipoles in the PVDF.

Construction of recoverable Ag2SeO3/Ag3PO4/MWCNT/PVDF porous film photocatalyst with enhanced photocatalytic performance for degrading Indigo carmine dye in continuous flow-loop photoreactor

Herein, a facile method was used for fabrication of composite based on Ag2SeO3 and Ag3PO4-Cube nanoparticles by co-precipitation method and subsequently was applied for construction of film composite by a casting solution containing polyvinylidene fluoride (PVDF) matrix, multi-walled carbon nanotubes (MWCNTs) as electron acceptor and carboxymethyl cellulose as a hydrophilic agent and Ag2SeO3/Ag3PO4 as photocatalyst filler via phase inversion technique. The synthesized porous film was used for photo-degradation of indigo carmine (IC) in a continuous flow-loop film photoreactor under LED and sunlight irradiation. The composite properties were described using various analyses such as FE-SEM, EDS, XRD, FTIR, PL and UV-Vis, EIS, Bode phase and water contact angle. The Ag2SeO3/Ag3PO4/MWCNT/PVDF film exhibits extensive photocatalytic activities for IC degradation in comparison to MWCNT/PVDF and Ag2SeO3/Ag3PO4 samples. According to the desirability function at optimum conditions lead to the IC photo-degradation efficiency of was around 97.88%. The enhanced visible light-based photocatalytic performance can be attributed to the high charge separation and the surface plasmon resonance (SPR) effect for IC photodegradation and experimental results illustrate that superoxide radicals as the main active radicals has high contribution on the IC photo-degradation. The low decrease in photocatalytic activity of the fabricated composite film after five uses makes the sample suitable for applications where reusability is a vital factor.

A ratiometric fluorescence amine sensor based on carbon quantum dot-loaded electrospun polyvinylidene fluoride film for visual monitoring of food freshness

A ratiometric fluorescence sensor based on dual-emission carbon quantum dots (CQD) was developed to real time monitor food spoilage. Two hydrophobic electrospun fluorescent films were developed using polyvinylidene fluoride (PVDF) as the film-forming polymer in combination with CQD as the fluorescent probe. The CQD/PVDF film and CQD@PVDF film enabled the analysis of TMA with limits of detection (LODs) of 1.04 μM and 2.1 μM, respectively, and they exhibited excellent stability at 4 °C. By these virtues, the CQD@PVDF film exhibited visible fluorescence color changes from yellow green to blue by real time and nondestructively sensing volatile amines generated from beef, pork and shrimp in a packaging system with high humidity. This strategy provided a simple but useful, non-destructive, robust, and platform to real time monitor food spoilage for intelligent food packaging.

Optoelectronic Properties of Polyvinylidene Fluoride Films Embedded with FAPbBr3 Nanocrystals Affected by Carrier Kinetics

Optoelectronic Properties of Polyvinylidene Fluoride Films Embedded with FAPbBr₃ Nanocrystals Affected by Carrier Kinetics

Doping effect on optical properties of pure and malachite green doped polyvinylidene fluoride films

The films of pure polyvinylidene fluoride (PVDF) and various concentration of malachite green (MG) doped have been prepared by solution cast method. The absorption spectra recorded by UV-VIS spectrophotometer 1700 Shimadzu. Absorbance versus wavelength spectra of pure and various concentration of MG doped PVDF films were observed in wavelength range 200-800 nm. With increasing malachite green in PVDF, intensity of absorbance edge and refractive index increases.

High Anti‐Jamming Flexible Capacitive Pressure Sensors Based on Core–Shell Structured AgNWs@TiO2

AbstractFlexible capacitive pressure sensors play an important role in electronic skin and human–machine interaction due to their high sensitivity and convenient preparation, comparing with those resistive/piezoresistive sensors. However, due to the complexity of the application environment, reported capacitive sensors often experience signal instability by electromagnetic interference and proximity effects. The great challenge for capacitive sensors is to maintain sensitivity and wide linear range while reducing interference. This study proposes a high anti‐jamming capacitive flexible pressure sensor with polyvinylidene fluoride (PVDF)@AgNWs@TiO2 film as the dielectric layer. Core–shell structure‐based AgNWs@TiO2 is embedded into the PVDF film. The introduction of the core–shell structure not only enhances the initial capacitance but also balances the dielectric constant, dielectric loss, and breakdown strength of the dielectric layer. The sensor is validated to exhibit a high signal‐to‐noise ratio for a variety of interference sources and is demonstrated with an intelligent glove sensing system, which provides a new idea for developing a high anti‐jamming capacitive flexible pressure sensor.

Structure and pyroelectric properties of PVDF ferroelectric films obtained by 3D printing

This article reports a method to produce polymer films of polyvinylidene fluoride (PVDF) by an additive manufacturing (3D printing). Method Fused Deposition Modeling (FDM) allows using PVDF and its copolymers not only in microelectronics as pyroelectric and piezoelectric sensors, as well as creating dynamic memory elements, organic solar cells and used in robotics. The surface morphology of the samples observed by scanning electron microscopy (SEM) presents in this paper. Pyroelectric measurements performed by the dynamic method show the presence of a noticeable pyroelectric response in PVDF films obtained using additive technologies, bypassing the orientation extraction stage. The calculation of the pyroelectric coefficient gives values corresponding to the values of the pyroelectric coefficient for PVDF samples obtained by traditional methods.

Osteogenic activity of bone: Novel approach of polyvinylidene fluoride films, marrow blood supply, and ultrasound stimulation

AbstractElectric fields used in bone stimulation are based on the application of direct current, but some drawbacks exist, such as the need for an external power source. Piezoelectric poly(vinylidene fluoride) (PVDF) has attracted interest for biomedical applications due to its flexibility, low toxicity, and the piezoelectric response to mechanical stimuli. This study aimed to investigate the effects of PVDF films on bone regeneration in rabbit tibias to assess the potential improvement in osteogenesis. An initial exploratory experiment was performed to determine optimal parameters for regulating the marrow blood supply. The second experiment focused on examining the effects of ultrasound stimulation on the implant's osteogenic capacity. The results showed that PVDF films have a notable impact on the extraskeletal bone formation and bone density in a secluded microenvironment with and without microperforations. At 60 days after surgery, tibias with marrow blood supply reached higher bone volumes and density and they were consistent with the cellular activity. Our results suggest that piezoelectric PVDF films have osteogenic characteristics and can be used to enhance new bone formation in a secluded space, thus reinforcing their biocompatibility nature. Additional studies are required to analyze the benefits of ultrasound stimulation.