Polyvinylidine Fluoride Research Articles

Geometrical and mechanical analysis of polylactic acid and polyvinylidine fluoride scaffolds for bone tissue engineering

Utilising finite element analyses and experimental testing, this study investigates the influence of scaffold porosity on mechanical behaviour and evaluates the potential of polylactic acid (PLA) and polyvinylidine fluoride (PVDF) as bone substitute materials. Scaffold geometries were devised using design parameters adapted from extant literature and then generated using computer-aided engineering tools. Methodical variations in strand thickness were applied, maintaining other design criteria constant for robust analysis. Results, derived under varied loading conditions, suggest that scaffold mechanical properties are influenced significantly by geometry, strand diameter and porosity. Cubic scaffolds exhibited marked strength. Structures with reduced porosity demonstrated heightened mechanical characteristics, while facilitating bone cell proliferation. For a comparative context, PVDF scaffolds were benchmarked against human femur bone properties, revealing a mechanical behaviour alignment, particularly in their Young’s modulus.

Activated carbon and its hybrid composites with manganese (IV) oxide as effectual electrode materials for high performance supercapacitor

Waste wood-dust of Dalbergia sisoo (Sisau) is presented, as a novel, low-cost, renewable, and sustainable source of agro-waste for the production of a highly porous activated carbon electrodes (Ds-electrodes) for supercapacitor. Ds-electrode was initially tested as supercapacitor electrode, which showed a lesser specific capacitance of 104.4 Fg −1 . Therefore, hybrid-composite-electrodes (HCEs) were fabricated by adopting the nanostructured “manganese IV oxide (MnO 2 )-activated carbon (Ds) composite” in various ratios as the core electrode materials. The HCEs was prepared via a simple facile mechanical mixing method and polyvinylidine fluoride (PVDF) polymeric solution was used as the electrode material binder. The experimental results showed that the 1:1 Ds: MnO 2 composite displayed highest specific capacitance of 300.2 Fg −1 , capacity retention of 96.3 % after 1000 cycles, 16.3 WhKg −1 of specific energy density at power density of 148.2 WKg −1 and low equivalent series resistance (ESR) value of 0.41 Ω at equivalent (1:1, Ds:MnO 2 ) loading of MnO 2 to Ds. It is clear that the equivalent (1:1) concentration of MnO 2 has improved the capacitive performance of the composite via pseudocapacitance charge storage mechanism as well as the enhancement on the specific surface area of the electrode. However, further increasing of the MnO 2 content (1:2, Ds:MnO 2 ) in the electrode was found to distort the capacitive performances and deteriorate the specific surface area of the electrode, mainly due to the aggregation of the MnO 2 particles within the composite.

Surface modification of grafted porous polyvinylidine fluoride membrane with graphene oxide for vanadium redox flow battery

Abstract Vanadium Redox Flow Battery (VRFB) is an energy storage flow battery in whichthe key material for VRFB is the membrane that determines the cost and performance of the battery. Porous membranes have shown a great potential as a membrane due to their high stability, cheap and high selectivity. Poly(vinylidine fluoride) (PVDF) is a type of porous membrane that was extensively studied as a potential material for surface modification due to its thermal and chemical stability, inexpensive and mechanical properties. This study aims to develop a highly selective, high-performance modified PVDF membrane using surface grafting and functionalization for VRFB application using the sonication method. Graphene oxide (GO) is a trending material in the field due to its excellent properties such as being highly resistant to alkaline/acidic and strong mechanical strength, low cost and easily accessible. In this work, GO was functionalized on both sides of grafted PVDF using the sonication technique. Hydrogen bond from modification with GO caused the membrane to be a hydrophilic and FTIR results proved that new peaks appeared which relates to carbon bond from GO. Proton conductivity of modified membrane is recorded higher than commercial VRFB membrane, Nafion.

Dimensional Effects of Polymer Piezoelectric Films for Wind Energy Harvesting

Abstract Arrays of flexible polymer piezoelectric film cantilevers that mimic grass or leaves is a prospective idea for harvesting wind energy in urban areas, where the use of traditional technologies is problematic due to low wind velocities. Conversion of this idea into an economically attractive technology depends on various factors including the shape and dimensions of individual films to maximize generated power and to minimize associated costs of production, operation, and maintenance. The latter requirement can be satisfied with rectangular films undergoing flutter in ambient air. Flexible piezoelectric films that displace due to low forces and can convert mechanical energy into electrical energy are ideal for this application. The goal of the presented study is to determine the key dimensions of the piezoelectric film to enhance generated power within the wind range characteristic for urban areas from 1.3 to 7.6 m/s. For this purpose, experiments were conducted in a wind tunnel using piezoelectric polymer films of polyvinylidine fluoride with the length, width, and thickness varying in the ranges of 32–150, 16–22, and 40–64 μm, respectively. Voltage and power outputs for individual samples were measured at wind speeds ranging from 0.5 to 16.5 m/s. Results demonstrated that a single film could produce up to 0.74 nW and that the optimal film dimensions are 63 mm × 22 mm × 40 μm (from considered samples) for the wind energy harvesting in urban areas. Further improvement in power production can be expected when using films with reduced thickness, low elastic modulus, and increased length, and by assembling films in arrays.

On the Solubility and Stability of Polyvinylidene Fluoride.

This literature review covers the solubility and processability of fluoropolymer polyvinylidine fluoride (PVDF). Fluoropolymers consist of a carbon backbone chain with multiple connected C–F bonds; they are typically nonreactive and nontoxic and have good thermal stability. Their processing, recycling and reuse are rapidly becoming more important to the circular economy as fluoropolymers find widespread application in diverse sectors including construction, automotive engineering and electronics. The partially fluorinated polymer PVDF is in strong demand in all of these areas; in addition to its desirable inertness, which is typical of most fluoropolymers, it also has a high dielectric constant and can be ferroelectric in some of its crystal phases. However, processing and reusing PVDF is a challenging task, and this is partly due to its limited solubility. This review begins with a discussion on the useful properties and applications of PVDF, followed by a discussion on the known solvents and diluents of PVDF and how it can be formed into membranes. Finally, we explore the limitations of PVDF’s chemical and thermal stability, with a discussion on conditions under which it can degrade. Our aim is to provide a condensed overview that will be of use to both chemists and engineers who need to work with PVDF.

Performance improvement of low frequency piezoelectric energy harvester incorporating holes with an in-house experimental set-up

The piezoelectric energy harvesters can be an integral part of self-powered sensor system due to its compatibility with semiconductor technology. In this paper, a modified structural geometry has been proposed in order to improve the performance of energy harvesters with classical cantilever topology by incorporating through holes. A detail mathematical analysis has been carried out to manifest the effect of through hole on resonant frequency of piezo harvester using Rayleigh–Ritz method. The theoretical analysis is validated through simulation studies as well as experimental results. Accordingly, an in-house low cost experimental set-up has been developed using Polyvinylidinefluoride (PVDF) based macro-level energy harvester and loud speaker based vibration set-up. It has been observed that the resonant frequency is reduced from 26.23 Hz to 21.94 Hz due to incorporation of hole to classical cantilever for a given dimension. With input acceleration of 3.7 g, the developed macro-harvester set-up resonates at 23 Hz and is capable of producing power of 59.93 $$\mu$$ W with hole based structure whereas power of 14.60 $$\mu$$ W is obtained in case of without hole based structure. The macro-scale energy harvester with modified geometry has been also designed and simulated in finite element analysis method to validate the mathematical analysis and it is found that lower the resonant frequency higher the power obtained with the hole based topology. It is verified from the experimental, simulation and theoretical studies, that there is a dominant effect of through hole in the performance improvement of piezoelectric energy harvester.

Dipolar Alignment in a Ferroelectric Dielectric Layer of FeFETs to Boost Charge Mobility and Nonvolatile Memory

Influence of dipolar alignments of a ferroelectric poly-vinylidine fluoride trifluroethylene [P(VDF-TrFE)] thin film on the charge mobility and nonvolatile property of ferroelectric field-effect transistors (FeFETs) has been explored. The electrical properties of the ferroelectric microstructures can be tuned by adopting different cooling procedures after annealing the spin-coated ferroelectric polymer P(VDF-TrFE) substrates. For example, a higher degree of alignment of the C–F dipoles in the polymeric chains is observed along the substrate surface for the samples with fast quenching. The dielectric constant of the fast-quenched sample is found to be ∼10 at 1 kHz, while the same is found to be ∼8.5 when the rate of cooling is relatively slower. Furthermore, the fabrication of a metal–insulator–metal capacitor using the fast-quenched substrate leads to a high remnant polarization of Pr ∼ 5.5 ± 0.2 μC/cm2, as compared to that of the normally cooled sample to ∼2.7 ± 0.2 μC/cm2, at an applied field intensity of 200 MV/m. Emergence of such characteristics encouraged the use of P(VDF-TrFE) as a gate dielectric layer, which leads to improved nonvolatile characteristics of the device. The measured charge carrier mobility of FeFETs embedded with a fast-quenched ferroelectric polymer as a gate dielectric is found to be ∼3.4 × 10–2 cm2 V–1 s–1, which is ∼35% higher than the normally cooled samples. The strongly correlated C–F dipoles in the fast-quenched ferroelectric layers lead to the reduction in width of the trap density of states near the semiconductor–dielectric interface. The XPS and UPS characterizations show the formation of a superior transport channel in the semiconductor near its dielectric interface when the fast-quenched polymer is used as the gate dielectric in the FeFETs.

Electrospinning of biomedically relevant multi-region scaffolds: From honeycomb to randomly-oriented microstructure

Here, we show a facile and one-step electrospinning strategy to fabricate multi-region scaffolds that display two main fibrillar microstructure arrays: honeycomb-like (HC) and randomly-oriented (RO), which are joined by an interface that aims to facilitate a smooth physical transition between them. Relevant design parameters including macropore size, fiber diameter, piezoelectric and mechanical properties were investigated. Our results show that polycaprolactone (PCL)-based scaffolds exhibited macropores in the HC and interface regions that could be tailored (from 867 ± 74 to 424 ± 27 μm and from 101 ± 10 to 80 ± 10, respectively) by increasing the electrospun polymer volume, while their fiber diameter distribution was not altered in a significant manner. Moreover, the local mechanical properties of these scaffolds changed in a discreet fashion according to each region's geometry, ensuring physical properties gradation from the RO to the HC zones. The versatility of this scaffold fabrication method was extended to the use of polyvinylidine fluoride (PVDF): while the macrostructural and mechanical properties were preserved, different fiber size distribution between the RO (353 ± 53 nm) and HC (251 ± 37 nm) regions as well as dissimilar fiber orientation were found, correlating with a variation in the piezoelectricity (β-phase fraction) within the scaffold. This fabrication technique could represent another alternative to engineer biocompatible multi-tissue systems with tunable structure and mechanics.

A sensitive and reversible staining of proteins on blot membranes

A modified, sensitive and reversible method for protein staining on nitrocellulose (NC) and polyvinylidine fluoride (PVDF) membranes was developed in Western blotting. The method employed Congo red staining to visualize proteins on different blot membranes. Staining of proteins with Congo red dye is more faster procedures. According to the experimental results, approximate 20 ng proteins could be detected in 3 min in room temperature. The staining on the proteins is easily reversible with Congo red destaining solution for NC and PVDF membranes, so that the blot membranes can be reused for Western blotting. In addition, we confirmed that the staining method is fully compatible with Western blot detection. NC and PVDF membranes treatment with Congo red staining does not interfere with conventional chemiluminescent substrates of peroxidase. As compared to MemCode reversible protein stain kits from Pirece Biotechnology, the staining technique is more sensitive, lower of cost, convenient and not adversely affecting subsequent Western blotting results. On the other hand, the stain is more sensitive than the Ponceau S staining. Therefore, Congo red staining is a promising and ideal alternative for current protein stain. Besides, the binding modes of Congo red or Ponceau S stain were investigated using various 2D and 3D molecular docking and demonstrated potential molecular basis for sensitivity of Congo red staining are higher than Ponceau S.

Preparation of PVDF/FMBO composite electrospun nanofiber for effective arsenate removal from water.

In this study, novel electrospun nanofibers (NFs) composed of organic polyvinylidine fluoride (PVDF) and inorganic Fe–Mn binary oxide (FMBO) nanoparticles were fabricated using an electrospinning technique for adsorptive decontamination of As(v) from polluted water. The NFs were prepared with doped solutions consisting of different weight ratios of PVDF/FMBO, in a NF matrix, ranging from 0 to 0.5. SEM, XRD, FTIR and TEM then characterized the NFs and FMBO particles. The XRD analysis indicated successful impregnation of FMBO nanoparticles in the NF matrix of the NFs investigated. An As(v) adsorption capacity as high as around 21.32 mg g−1 was obtained using the NF containing the highest amount of FMBO nanoparticles (designated as PVDF/FMBO 0.5). Furthermore, the adsorptive performance of the PVDF/FMBO 0.5 nanofiber could be easily regenerated using diluted alkaline solution (NaOH and NaOCl).

Enhancement of magnetic properties of PVDF by synthesize nano composite using NiZn ferrite

The (XRD) patterns of the samples Ni0.5Zn0.5Fe2O4 in the form of powder were prepared using the ball milling technique for 41, 67 and 90 hours and were annealed at 1073, 1273 and 1373 K and (Poly vinylidine Fluoride) (PVDF) and composite samples of x% Ni0.5Zn0.5Fe2O4/PVDF, (x% = 5, 10, 15, 20 and 25%) have been studied. The α phase decrease and β-phases increase by increasing the ferrite content suggesting less crystallinity producing an amorphous structure of PVDF at x = 25% ferrite where as β PVDF nucleates in the composites The electric polarization increases by increasing NZF content. The transition from ferromagnetic (order state) to paramagnetic (disorder state) occurs at Curie temperature TC (600K). The DC resistivity is nearly constant from 153k to 286k for all composite samples and then decreases at high temperature. The behavior of dielectric constant and dielectric loss was measured in the temperature range from 200K to 700K. With the increase of magnetic content, the saturation magnetization (Ms) value of the composites also increases.

Feasibility of Biohydrogen Purification from Carbon Dioxide Mixture via Integrated Microalgae-Membrane Contactor Towards Zero Carbon Emission

Biohydrogen (H2) mixed with carbon dioxide (CO2) produced from the fermentation of Palm Oil Mill Effluent (POME) could be a potential renewable energy source. However, an effective technique to treat both gases towards zero carbon emission has become a major concern. In this study, a new approach was introduced to treat H2/CO2 mixture from POME fermentation by an integrated microalgae-membrane contactor system. Polyvinylidine fluoride (PVDF) hollow fibre membrane used in the integrated membrane contactor system abled to give the highest purified H2% from mixed H2/CO2 in the microalgae liquid absorbent (Chlorella Vulgaris) (69.4%) followed by Bold Basal Medium (BBM) (59.1%) and distilled water (55.9%). This initial result showed that the microalgae possessed better ability to absorb CO2 into the liquid stream via the PVDF membrane contactor. Next, investigation on optimizing the system’s operational parameters using BBM as liquid absorbent showed the highest CO2 absorption flux and efficiency were obtained at initial solution pH of 10. Further investigation showed that the absorption efficiency was enhanced as the liquid flow rate increased up to 0.4 L/min and the gas flow rate was at 0.1 L/min. Upon utilizing 0.6 g/L microalgae, the purified H2% found to remarkably increase up to 83.2%. In conclusion, the use of the developed integrated microalgae-membrane contactor system to purify the bio-H2 from CO2 mixture is a promising alternative method for zero carbon emission especially in palm oil industry.

Third order nonlinear optical properties of β enhanced PVDF based nanocomposite thin films

PVDF based nanocomposite thin films have received great interest in energy harvesting, ferroelectric, pyroelectric and dielectric applications. In this novel study, we have exploited the electroactive β-phase (polar) formation in polyvinylidine fluoride–halloysite nanotube (PVDF–HNT) nanocomposite thin films fabricated by the spin coating technique for nonlinear optical applications. It was demonstrated that HNTs of different volume percentage loadings in the PVDF matrix were able to effectively nucleate PVDF in β (TTTT-all trans) conformation using X-ray diffraction and Infrared spectroscopy techniques. Closed aperture Z-scan measurements were performed for all the thin film samples with a CW laser as an excitation source at a wavelength of 632.8 nm. We observed a sign change in the nonlinear refractive index for PVDF. Nonlinear refractive index has a negative sign for pristine PVDF and a positive sign for HNT incorporated PVDF thin films. This anomalous behavior of change in the nonlinear refraction of PVDF is explained in our present work.

Investigation of Nanocomposite Polymer Electrolytes for Lithium Ion Batteries

Composite polymer electrolytes based on polyvinyl alcohol: polyvinylidine fluoride: lithium triflate doped with different concentration of nanosilica have been prepared by the solution casting technique. The prepared films are transparent and mechanically stable. Interaction of SiO2 nanoparticles with the host polymer in the composite polymer electrolyte has been confirmed using X-ray diffraction, Fourier transform infrared spectroscopy, and photoluminescence spectra. Dispersion of nanofiller in the polymer matrix help to increase the free volume of the system and thus increases amorphous nature. The optimal composition of composite polymer electrolytes was found possessing high conductivity, thermal, mechanical and electrochemical stability, which will be well suited for lithium ion battery applications.

Effect of electrospinning parameters on morphological properties of PVDF nanofibrous scaffolds

Smart materials like piezoelectric polymers represent a new class of promising scaffold in neural tissue engineering. In the current study, the fabrication processing parameters of polyvinylidine fluoride (PVDF) nanofibrous scaffold are found as a potential scaffold with nanoscale morphology and microscale alignment. Electrospinning technique with the ability to mimic the structure and function of an extracellular matrix is a preferable method to customize the scaffold features. PVDF nanofibrous scaffolds were successfully fabricated by the electrospinning technique. The influence of PVDF solution concentration and other processing parameters like applied voltage, tip-to-collector distance, feeding rate, collector speed and the solvent were studied. The optimal parameters were 30 w/v% PVDF concentration, 15 kV applied voltage, 18 cm tip-to-collector distance, 0.5 ml/h feeding rate, 2500 rpm collector speed and N,N′-dimethylacetamide/acetone as a solvent. The mean fiber diameter of the obtained scaffold was 352.9 ± 24 nm with uniform and aligned morphology. Finally, the cell viability and morphology of PC-12 cells on the optimum scaffold indicated the potential of PVDF nanofibrous scaffold for neural tissue engineering.

Unique Multilayered Assembly Consisting of “Flower-Like” Ferrite Nanoclusters Conjugated with MWCNT as Millimeter Wave Absorbers

Unique multilayered assembly was designed here using polymeric blends containing “flower-like” ferrite nanoparticles conjugated with multiwall carbon nanotubes (MWCNTs) for attenuating 99.999% of the incoming electromagnetic (EM) radiation. In comparison to a traditional single layered structure, this unique assembly is superior for myriad applications related to suppressing the incoming EM radiation, mostly by absorption. The three key requirements—impedance wave matching, absorption, and multiple scattering from the heterogeneous structures—were accounted here by suitably modifying the nanomaterials. A bicomponent blend consisting of two immiscible polymers, polyvinylidine fluoride (PVDF) and polycarbonate (PC), was used here to construct the multilayered assembly wherein selective localization of nanoparticles in one of the components, driven by thermodynamics, reduced the percolation threshold of the nanoparticles. In order to improve the impedance matching, MWCNTs were functionalized using the defect...

Measurement of Pressure Fluctuations inside a Model Thrust Bearing Using PVDF Sensors.

Thrust bearings play a vital role in propulsion systems. They rely on a thin layer of oil being trapped between rotating surfaces to produce a low friction interface. The “quality” of this bearing affects many things from noise transmission to the ultimate catastrophic failure of the bearing itself. As a result, the direct measure of the forces and vibrations within the oil filled interface would be very desirable and would give an indication of the condition of the bearing in situ. The thickness of the oil film is, however, very small and conventional vibration sensors are too cumbersome to use in this confined space. This paper solves this problem by using a piezoelectric polymer film made from Polyvinylidine Fluoride (PVDF). These films are very thin (50 μm) and flexible and easy to install in awkward spaces such as the inside of a thrust bearing. A model thrust bearing was constructed using a 3D printer and PVDF films inserted into the base of the bearing. In doing so, it was possible to directly measure the force fluctuations due to the rotating pads and investigate various properties of the thrust bearing itself.

Direct Deposit of Highly Reactive Bi(IO3)3‐ Polyvinylidene Fluoride Biocidal Energetic Composite and its Reactive Properties

Metal iodate oxidizers are synthesized and evaluated as oxidizers in thermite reactions to generate both heat and a biocidal reaction product for bioagent defeat. TGA/DSC/MS and T‐jump TOFMS analysis show gas‐phase iodine release from metal iodate decomposition at both low and high heating rates. In constant volume combustion tests, Bi(IO3)3/Al thermite outperforms other metal iodate/Al and traditional thermites. Mechanically sound composites with high mass loadings of particulates are formed by direct electrospray of synthesized metal iodates, nanoaluminum fuel, and polyvinylidine fluoride (PVDF) binder/oxidizer, and burn speeds are measured in both air and argon atmospheres.

Enhanced mass transfer rate of methane via hollow fiber membrane modules for Methylosinus trichosporium OB3b fermentation

Polyvinylidine fluoride (PVDF) hollow fiber membranes were employed to enhance mass transfer rate of methane in water for the fermentation of Methylosinus trichosporium OB3b. Compared to common alumina bubbler, hollow fiber membrane modules (HFMMs) afforded smaller methane bubble size and larger methane–water volumetric mass transfer coefficient (kLa) as high as 150.1h−1. Furthermore, cell growth rate and maximum optical density of M. trichosporium OB3b were increased by 67.3 and 77.4%, respectively, by adapting forty HFMMs, compared to those of alumina bubbler.

Development of a Microforce Sensor and Its Array Platform for Robotic Cell Microinjection Force Measurement.

Robot-assisted cell microinjection, which is precise and can enable a high throughput, is attracting interest from researchers. Conventional probe-type cell microforce sensors have some real-time injection force measurement limitations, which prevent their integration in a cell microinjection robot. In this paper, a novel supported-beam based cell micro-force sensor with a piezoelectric polyvinylidine fluoride film used as the sensing element is described, which was designed to solve the real-time force-sensing problem during a robotic microinjection manipulation, and theoretical mechanical and electrical models of the sensor function are derived. Furthermore, an array based cell-holding device with a trapezoidal microstructure is micro-fabricated, which serves to improve the force sensing speed and cell manipulation rates. Tests confirmed that the sensor showed good repeatability and a linearity of 1.82%. Finally, robot-assisted zebrafish embryo microinjection experiments were conducted. These results demonstrated the effectiveness of the sensor working with the robotic cell manipulation system. Moreover, the sensing structure, theoretical model, and fabrication method established in this study are not scale dependent. Smaller cells, e.g., mouse oocytes, could also be manipulated with this approach.