Query: PVDF pirezoelectric

title: Stretchable Electrospun PVDF HFP/Co ZnO Nanofibers as Piezoelectric Nanogenerators
abstract: Herein, we investigate the morphology, structure and piezoelectric performances of neat polyvinylidene fluoride hexafluoropropylene (PVDF HFP) and PVDF HFP/Co ZnO nanofibers, fabricated by electrospinning. An increase in the amount of crystalline b phase of PVDF HFP has been observed with the increase in Co doped ZnO nanofiller concentration in the PVDF HFP matrix. The dielectric constants of the neat PVDF HFP and PVDF HFP/2 wt. Co ZnO nanofibers are derived as 8 and 38 respectively. The flexible nanogenerator manipulated from the polymer nanocomposite (PVDF HFP/Co ZnO) exhibits an output voltage as high as 2.8 V compared with the neat PVDF HFP sample ~120 mV) These results indicate that the investigated nanocomposite is appropriate for fabricating various flexible and wearable self powered electrical devices and systems.

title: Porous PVdF/GO Nanofibrous Membranes for Selective Separation and Recycling of Charged Organic Dyes from Water.
abstract: Graphene oxide (GO) membranes are robust and continue to attract great attention due to their fascinating properties, despite their potential issues regarding stability and selectivity in aqueous phase processing. That being said, however, the functional moieties of GO could be used for membrane surface modification, while ensuring simultaneous removal and recycling of industrial organic dyes. Herein, we present a versatile porous structured polyvinylidene fluoride graphene oxide (PVdF GO) nanofibrous membranes (NFMs) prepared by using simple and straightforward electrospinning approach for selective separation and filtration. The GO nanosheets were distributed homogeneously throughout the PVdF nanofiber, regulating the surface morphology and performance of PVdF GO NFM. The PVdF GO NFMs possesses high mechanical strength and surface free energy (SFE) consequently resulting high permeation and filtration efficiency as compared to PVdF NFM. The selectivity (99% toward positively charged dyes based on electrostatic attraction, while maintaining rejection (100% for negatively charged dye from mixed solutions highlight the role of GO in PVdF GO NFM, owing to uniform pores and negatively charged surface. In addition, the actual efficiency of NFMs could be recovered easily up to three consecutive filtration cycles by regeneration, thereby assuring high stability. The high permeation, purification and filtration efficiency, good stability and recycling of PVdF GO NFMs are promising for use in practical water purification and applications, particularly for selective filtration and recycling of dyes.

title: Superior performances of in situ synthesized ZnO/PVDF thin film based self poled piezoelectric nanogenerator and self charged photo power bank with high durability
abstract: Herein, we have synthesized multitalented b crystallite prosperous and high dielectric ZnO/PVDF thin films via in situ process for energy harvesting and energy storing applications. The impregnation of the ZnO nanoparticles (NPs) in PVDF matrix has enhanced the electroactive b crystal nucleation (F(b) 84% at 0.85 vol% doping) as well as piezoelectricity (d33 50 pC/N at 50 Hz) and the dielectric value 109 at 1.7 vol% loading) effectively. The nanogenerator, named as ZPENG and the self charged photo power bank (PPB) developed using the optimized supercilious piezoelectric and dielectric films have exhibited superiority in power generation (power density 32.5 mW/cm3) and energy storage capability 2000 F/ respectively that are highly impressive outputs compare to other similar prototype devices reported elsewhere till now. The realistic utilities of our fabricated ZPENG have been proved by light up 15 serially connected commercial blue light emitting diodes (LEDs) and charging capacitor (1 mF) in a small time span under repetitive finger impartation. The ZPENG is also shows continuous band like power generation under vibration occurred due to blood circulation in human body. The self charged PPB is also able to power up blue LED that has confirmed its realistic applicability as a power source.

title: Surface modified BaTiO3 nanoparticles by titanate coupling agent induce significantly enhanced breakdown strength and larger energy density in PVDF nanocomposite
abstract: Dielectric capacitors are promising in micro electronics, portable equipment and hybrid electric vehicles due to their specific features of flexibility, ultrahigh operating voltage and fast charging discharging rate. The dielectric properties of polymer based nanocomposite are much related to the interface binding between fillers and matrix. In this work, a surface modification approach employed newfound titanate coupling agent was developed to improve the compatibility between BT nanoparticles and PVDF matrix. After treated by the modifier TC 2, a coating layer contained with active organic groups was formed on the surface of BT nanoparticles. Benefited from the improved dispersibility and compatibility of modified BT nanoparticles in PVDF matrix, the breakdown strength of the nanocomposites was much enhanced. The monodisperse mBT 2 nanoparticles treated with appropriate amount of modifier dramatically enlarged the breakdown strength from 397 kV/mm for neat PVDF to 517 kV/mm for 4 vol% mBT 2 loading nanocomposite. Compared with BT/PVDF, the improvements on the energy storage performance in mBT 2/PVDF are significant. The maximum discharged energy density of 11.27 J/cm3 for 4 vol% loading mBT 2/PVDF is nearly double of that for 4 vol% loading BT/PVDF, and the energy efficiency for mBT 2/PVDF is also increased. The modification method originally represented here has great potential in developing high energy density nanocomposites for advanced applications.

title: PVDF/Palygorskite Nanowire Composite Electrolyte for 4 V Rechargeable Lithium Batteries with High Energy Density.
abstract: Solid electrolytes are crucial for the development of solid state batteries. Among different types of solid electrolytes, poly(ethylene oxide) (PEO) based polymer electrolytes have attracted extensive attention owing to their excellent flexibility and easiness for processing. However, their relatively low ionic conductivities and electrochemical instability above 4 V limit their applications in batteries with high energy density. Herein, we prepared poly(vinylidene fluoride) (PVDF) polymer electrolytes with an organic plasticizer, which possesses compatibility with 4 V cathode and high ionic conductivity (1.2 x 10 4 S/cm) at room temperature. We also revealed the importance of plasticizer content to the ionic conductivity. To address weak mechanical strength of the PVDF electrolyte with plasticizer, we introduced palygorskite (Mg,Al)2Si4O10(OH) nanowires as a new ceramic filler to form composite solid electrolytes (CPE) which greatly enhances both stiffness and toughness of PVDF based polymer electrolyte. With 5 wt of palygorskite nanowires, not only does the elastic modulus of PVDF CPE increase from 9.0 to 96 MPa but also its yield stress is enhanced by 200% Moreover, numerical modeling uncovers that the strong nanowire polymer interaction and cross linking network of nanowires are responsible for such significant enhancement in mechanically robustness. The addition of 5% palygorskite nanowires also enhances transference number of Li+ from 0.21 to 0.54 due to interaction between palygorskite and ClO4 ions. We further demonstrate full cells based on Li(Ni1/3Mn1/3Co1/3)O2 (NMC111) cathode, PVDF/palygorskite CPE, and lithium anode, which can be cycled over 200 times at 0.3 C, with 97% capacity retention. Moreover, the PVDF matrix is much less flammable than PEO electrolytes. Our work illustrates that the PVDF/palygorskite CPE is a promising electrolyte for solid state batteries.

title: Polarization free high crystallization b PVDF piezoelectric nanogenerator toward self powered 3D acceleration sensor
abstract: The strong piezoelectric lead zirconate titanate (PZT) ceramic with inherent brittleness and highly tough Poly (vinylidene fluoride) (PVDF) polymer with intrinsic weak piezoelectricity cannot simultaneously fulfill the requirements of high sensitivity and excellent stability as a piezoelectric acceleration sensor in extreme service environments, such as intense impact. Here, we developed a polarization free high crystallization b PVDF (hb PVDF) based piezoelectric nanogenerator (PENG) as acceleration sensor with high sensitivity (2.405 nA s2 m 1) and excellent stability (97% remaining after 10000 cycles) Fundamentally, the excellent performance benefits from the PVDF by high pressure melt crystallization with a high b phase crystallinity of 86.48% indicative of the enhanced piezoelectricity (high short circuit current density of 145 nA cm 2) With integration of PENGs in three axes, the self powered 3D acceleration sensor is developed for vector acceleration measurement in any directions. Moreover, a dynamic 3D frequency and acceleration sensor system is targetedly applied to cooperate the acceleration sensor for real time collision monitoring and alert signal transmission, which presents a significant step toward vehicle safety monitoring. Therefore, we believe this easy process of hb PVDF and device has potential for commercial production in the field of transportation, self powered devices, and energy harvesting.

title: Improvement of antifouling performances for modified PVDF ultrafiltration membrane with hydrophilic cellulose nanocrystal
abstract: Hydrophilic cellulose nanocrystal (CNC) was incorporated into hydrophobic poly(vinylidene fluoride) (PVDF) membrane via phase inversion process to improve membrane antifouling property. The effects of CNC on membrane morphology, hydrophilicity, permeability and antifouling property were investigated in detail. Results indicated that the introduction of CNC into PVDF membrane enhanced the permeability by optimizing membrane microstructure and improving membrane hydrophilicity. A higher pure water flux of 206.9 L m 2 h 1 was achieved for CNC/PVDF membrane at 100 kPa, which was 20 times that of PVDF membrane (9.8 L m 2 h 1) In bovine serum albumin filtration measurements, the permeation flux and flux recovery ratio of CNC/PVDF membrane were increased remarkably, while the irreversible fouling resistance of CNC/PVDF membrane decreased by 48.8% These results indicated that the CNC/PVDF membrane possessed superior antifouling property due to the hydrophilicity of CNC that formed a hydration layer on the membrane surface to effectively reduce contaminants adsorption/deposition.

title: Simplified and robust adhesive free superhydrophobic SiO2 decorated PVDF membranes for efficient oil/water separation
abstract: A simplified adhesive free strategy for fabricating robust superhydrophobic polyvinylidene fluoride (PVDF) oil/water separation membranes was developed. SiO2 nanoparticles were strongly fixed to the surface of the "adhesive" PVDF membranes via delayed phase inversion. Oil/water filtration membranes with micro nano coarse structures and low surface energies were obtained by adjusting the SiO2 concentration in a coagulation bath. The membrane structure was analyzed via Fourier transform IR and X ray photoelectron spectroscopy. The evolution of the morphology, performance of the membranes, and the filtration properties were investigated using scanning electron microscopy and confocal scanning microscopy, among other techniques. The obtained SiO2 nanoparticle decorated PVDF membrane has a water contact angle of 157 2deg and an oil contact angle of 0 deg. The superhydrophobic PVDF membranes had extremely high chloroform fluxes, over 10,000 L/(m2 h) at 0.9 bar, and could be used for the separation of oil water mixtures and surfactant stabilized water in oil emulsions. The separation efficiency (approximately 99.95% in terms of the oil purity in the filtrate) was high. Furthermore, the fabricated PVDF oil/water filtration membranes exhibited good stability and excellent recyclability (over 20 cycles) The proposed eco friendly and straightforward strategy provides new insights for the development of practical oil/water filtration membranes.

title: Tactile Sensing Based on Flexible PVDF Nanofibers via Electrospinning: A Review
abstract: The flexible tactile sensor has attracted widespread attention because of its great flexibility, high sensitivity, and large workable range. It can be integrated into clothing, electronic skin, or mounted on to human skin. Various nanostructured materials and nanocomposites with high flexibility and electrical performance have been widely utilized as functional materials in flexible tactile sensors. Polymer nanomaterials, representing the most promising materials, especially polyvinylidene fluoride (PVDF) PVDF co polymer and their nanocomposites with ultra sensitivity, high deformability, outstanding chemical resistance, high thermal stability and low permittivity, can meet the flexibility requirements for dynamic tactile sensing in wearable electronics. Electrospinning has been recognized as an excellent straightforward and versatile technique for preparing nanofiber materials. This review will present a brief overview of the recent advances in PVDF nanofibers by electrospinning for flexible tactile sensor applications. PVDF, PVDF co polymers and their nanocomposites have been successfully formed as ultrafine nanofibers, even as randomly oriented PVDF nanofibers by electrospinning. These nanofibers used as the functional layers in flexible tactile sensors have been reviewed briefly in this paper. The b phase content, which is the strongest polar moment contributing to piezoelectric properties among all the crystalline phases of PVDF, can be improved by adjusting the technical parameters in electrospun PVDF process. The piezoelectric properties and the sensibility for the pressure sensor are improved greatly when the PVDF fibers become more oriented. The tactile performance of PVDF composite nanofibers can be further promoted by doping with nanofillers and nanoclay. Electrospun P(VDF TrFE) nanofiber mats used for the 3D pressure sensor achieved excellent sensitivity, even at 0.1 Pa. The most significant enhancement is that the aligned electrospun core shell P(VDF TrFE) nanofibers exhibited almost 40 times higher sensitivity than that of pressure sensor based on thin film PVDF.

title: PVDF based dielectric polymers and their applications in electronic materials
abstract: The attractive dielectric poly(vinylidene fluoride) (PVDF) and its copolymers are well confirmed possessing the highest electroactive response including dielectric constant, piezoelectric and ferroelectric effects, which have increasingly wide range of applications such as in energy transfer, energy generation and storage, monitoring and control, and include the development of capacitors, sensors, actuators and so on. In this study, by clarifying the reliability of dielectric performances on their crystal phase structure of various PVDF polymers, the different physical and chemical fabricating ways to achieve different forms of PVDF samples such as linear polymers, ferroelectrics, and relaxor ferroelectrics were identified and quantified. In addition, many recent advances in the PVDF based polymer dielectrics and some developed applications of these polymers are presented, which gives a reference in academic and engineering area to select an appropriate PVDF series dielectric polymer.