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In this work, we designed a novel polyvinylidene fluoride (PVDF)@DNA solid polymer electrolyte, wherein DNA, as a plasticizer-like additive, reduced the crystallinity of the solid polymer electrolyte and improved its ionic conductivity. At the same time, due to its Lewis acid effect, DNA promotes the dissociation of lithium salts when interacting with lithium salt anions and can also fix the anions, creating more free lithium ions in the electrolyte and thus improving its ionic conductivity. However, owing to hydrogen bonding between DNA and PVDF, excess DNA occupies the lone pairs of electrons of the fluorine atoms on the PVDF molecular chains, affecting the conduction of lithium ions and the conductivity of the solid electrolyte. Hence, in this study, we investigated the effects of adding different DNA amounts to solid polymer electrolytes. The results show that 1% DNA addition resulted in the best improvement in the electrochemical performance of the electrolyte, demonstrating a high ionic conductivity of 3.74 × 10−5 S/cm (25 °C). The initial capacity reached 120 mAh/g; moreover, after 500 cycles, the all-solid-state batteries exhibited a capacity retention of approximately 71%, showing an outstanding cycling performance. [ABSTRACT FROM AUTHOR]

The notch effect of semicrystalline PVDF was investigated using U- and V-notch geometries with different depths, and tensile tests were performed at 23 °C using the DIC technique and FEA. Both unnotched and notched dumbbell-shaped specimens were subjected to tensile loading with the DIC technique to obtain mechanical curves and strain maps. The experimental data were compared to a numerical model, analyzing both global mechanical curves and local strain maps around the notch region to assess the accuracy of the simulations. The results demonstrated that the geometry and depth of the notch influence the mechanical behavior of PVDF, presenting a decrease in load and displacement compared to unnotched specimens. This aspect was corroborated by strain maps, which showed the increase in the local strain around the notch tip. For FEA, the global analysis indicated a good correlation with experimental results, and the local analysis demonstrated a reasonable agreement in strain map results within 0.5 mm of the notch neighborhood. Overall, the DIC technique and FEA provided a reliable evaluation of notch behavior on the PVDF used as pressure sheaths with reasonable precision. [ABSTRACT FROM AUTHOR]

The crystal structure has a great influence on the dielectric and piezoelectric performance of poly(vinylidene fluoride) (PVDF). In this work, we prepared PVDF films with two typical crystalline phases (α and β). In situ Kelvin probe force microscopy (KPFM) and Piezoelectric force microscopy (PFM) were employed to investigate the responses of different PVDF crystalline phases to charge mobility, polarization, and piezoelectric properties. We used a homemade Kelvin probe force microscope (KPFM) to inject charges into the two crystalline phases to investigate the differences in the response of different crystalline phases of PVDF to electrical excitation on a microscopic scale. It was found that the α-phase has a lower charge injection barrier and is more susceptible to charge injection and that the α-phase is accompanied by a faster charge dissipation rate, which makes it easier to accumulate charge at the interface between the α-phase and β-phase PVDF. Moreover, the PFM polarization manipulation showed no change in the amplitude and phase diagram of the α-phase under ±10 V bias. In contrast, the β-phase showed a clear polarization reversal phenomenon and a significant increase in piezoelectric amplitude, which is consistent with its polar intrinsic properties. This study provides valuable insights into the multiphase contributions and a reference for designing advanced PVDF dielectrics. [ABSTRACT FROM AUTHOR]

The rising widespread oil‐impacted wastewater warrants an urgent call for innovative approaches to the handling of oily wastewater. A variety of techniques has been investigated to treat oil‐impacted water, and they are found to be inefficient. Electrospun nanofibers emerge as the viable technique to treat oily wastewater precisely owing to their high specific surface areas and interconnected nanoscale pore structures. In this review, a brief background on the study is provided followed by the environmental pollution by the oily wastewater. Subsequent to that, the polyvinylidene fluoride (PVDF) modification methods are also presented followed by the physicochemical properties of both the electrospun PVDF blends and the PVDF‐based composites. Furthermore, the performances of the PVDF‐based composites in oil/water separation are described. It is concluded with the future prospects for using PVDF‐based composites for oil/water separation. [ABSTRACT FROM AUTHOR]

Given global water scarcity and the quest for sustainable energy, there's a pressing need for integrated approaches addressing water‐energy interdependence worldwide. A practical approach for this challenge involves the implementation of fog water collectors. Herein, a polyvinylidene fluoride (PVDF) multifunctional device capable of harvesting water and electricity from wind is developed and tested, collecting up to 365 mg cm−2 h−1 of fog water. Due to the piezoelectric nature of electrospun PVDF, these yarns and meshes not only serve as piezoelectric sensors, enabling the detection of incoming fog flow and determination of its speed and, bust also harvest electricity by charging a capacitor, making it a green and renewable power source. In this study, promising insights are offered into developing efficient fog water collection methods and utilizing piezoelectric fiber‐based yarns and meshes for multifunctional applications in sustainable water management, energy harvesting, and sensing in a single device. [ABSTRACT FROM AUTHOR]

In this work, a strain sensor was fabricated using conductive electrospun polyvinylidene fluoride (PVDF) nanofiber film coated with carbon nanotubes (CNTs) on a polyimide (PI) substrate. An investigation of the sensor's properties during stretching and relaxation under varying experimental conditions was undertaken. The morphologies of the sensing films were examined to gain an understanding of their structure. The experimental design was complemented by simulation to optimize the shape and size of the substrate to ensure uniform and consistent straining under loading conditions. The insight derived from the computational analysis played an instrumental role in selecting the appropriate substrate design and determining the ideal location for placing the PVDF/CNTs sensing film. The difference in the deformation value of the substrate with the selected design during the computational and experimental analysis was 17.5%. An integrated approach, combining both experimental and computational methodologies, was used to significantly enhance the study's value and facilitate the development of an efficient and effective strain sensor. The sensor displayed a gauge factor (GF) of 1.83 and 1.19 under the incremental loads of 0.98 and 1.96 N, respectively. In conclusion, this study contributes to an improved understanding of the strain sensor's characteristics and potential applications in structural health monitoring technologies. [ABSTRACT FROM AUTHOR]

The quest for efficient and sustainable methods to mitigate carbon dioxide (CO2) emissions is a pressing global challenge. This study delves into the crucial role of polymers in tailoring the performance of titanium dioxide (TiO2) nanofibers for CO2 conversion reactions. By systematically comparing the influence of different polymers, specifically polyvinyl pyrrolidone (PVP) and polyvinylidene fluoride (PVDF), on the CO2 conversion activity of TiO2-NFs, we shed light on the remarkable potential of polymeric selection to fine-tune catalyst properties. The paper uses advanced experimental techniques to analyze the structural and morphological properties of PVP-TiO2-NFs and PVDF- TiO2-NFs demonstrating their various morphologies. The investigation involves SEM, XRD, BET, Raman, and UV-Vis spectroscopy to better understand the charge separation and recombination processes involved in both materials' CO2 conversion. The results show considerable differences, the choice of polymer significantly impacts the CO2 conversion performance of TiO2-NFs. PVP-based NFs exhibit enhanced surface area and porosity, resulting in superior catalytic activity, while PVDF-based NFs demonstrate remarkable stability. These findings pave the way for innovative approaches to tackle climate change and develop a more environmentally friendly future by advancing energy-efficient and long-lasting photocatalytic technology. [ABSTRACT FROM AUTHOR]

Hypertension is a common cause of cardiovascular diseases, closely associated with the high mortality and disability rates of cardiovascular diseases such as stroke and coronary heart disease. Therefore, developing a comfortable and sustainable device for monitoring human pulse signals holds practical significance for the prevention and treatment of hypertension and cardiovascular diseases. PVDF flexible pressure sensors possess the characteristics of high sensitivity, good flexibility, and strong biocompatibility, thereby demonstrating extensive application potential in areas such as health monitoring, wearable devices, and electronic skins. This paper focuses on the development of a modified piezoelectric polymer and its application in an intelligent blood pressure monitoring system, demonstrating its outstanding performance and feasibility through a series of experiments. This research provides innovative material choices for the development of intelligent medical devices and offers beneficial guidance for the design and application of future intelligent health monitoring systems. [ABSTRACT FROM AUTHOR]

With the increasing demand for self-adaptive electronics, stretchable and conformable sensors with high sensitivity, stretchability, and self-adhesive are significant intelligent devices. Here a novel tactile sensor is demonstrated that maintains conformal contact to the object for efficient movement monitoring. The device, which was composed of the "H" well-manicured thermoplastic elastomer (TPE), a rectangular polyvinylidene fluoride (PVDF) film coupled with a silver electrode and clamped into the copper-clad signal line ends, and a "U" shaped super-elastic silica gel layer, provided satisfactory performance. The device was investigated as a dynamic monitoring sensor due to its stretchable and conformal configuration. The mechanical stability and high sensitivity suggested that, when attached to the skin of participants, the sensor detected motion induced strain which was experimentally demonstrated. The results show that the novel biomimetic sensor is effective in monitoring human dynamics, with an accuracy exceeding than 98.3%. The stretchable and conformable sensor is low-cost and nontoxic with potential applications in clinical, conformal detection, and artificial intelligence. [ABSTRACT FROM AUTHOR]

Nanofiber (NF) products exhibit outstanding performances in materials science, textiles, and medicine that cannot be realized using conventional technologies. However, the safety of such products is debated because of the potential health risks that nanomaterials pose and the lack of standardized guidelines for the safety evaluation of NF products. The global safety evaluations of nanomaterials have focused on evaluating the cytotoxicity of low-dimensional materials, including nanoparticles and nanotubes, based on OECD (Organization for Economic Co-operation and Development) criteria. NFs are one-dimensional materials with nanometer diameters and considerable lengths. Many fibers are applied in a densely woven web-like form, so assessing cellular penetration and fiber toxicity using the same methods is inappropriate. This study verifies the safety of the polyurethane (PU) and polyvinylidene fluoride (PVDF) polymers currently applied in filters and masks. To this end, polymer NFs were collected from each product, and the NFs were compared with reference samples using FT-IR and Raman spectroscopy. For the safety evaluation, DMSO stocks of varying concentrations of PVDF and PU NFs (at 0.5, 1, 5, and 10 μg/mL) were prepared. The cytotoxicity and inhibitory effects on nitric oxide production and protein expression obtained via Western blot were identified. [ABSTRACT FROM AUTHOR]

The effect of content in the piezoelectric response of poly (vinylidene fluoride) (PVDF)/BaTiO3 nanocomposites has been investigated in this work. The morphology of PVDF-BaTiO3 composite films was characterized using scanning electron microscopy (SEM). Fourier transforms infrared (FTIR) spectroscopy and X-ray diffractometry (XRD) were used to investigate the phase analysis of samples. Voltage output increases significantly with increasing filler content. The electroactive ß-phase of PVDF is nucleated by the presence of the ceramic filler, the effect being strongly dependent on filler content. The results revealed that incorporating the functionalized BaTiO3 nanoparticles within the PVDF layer increases the piezoelectric response of pure PVDF compared to the sample with incorporated pure sample. Increasing concentration caused enhanced piezoelectric response. [ABSTRACT FROM AUTHOR]

Currently, one of the priority tasks is the development of intelligent materials that are sensitive to stimuli and can be used in catalytic applications for efficient decomposition of organic pollutants. Particularly relevant in this regard is the development of inexpensive non‐metallic hybrid polymer photocatalysts, and the explanation of the mechanism of using light energy in such systems is still the subject of open discussions. In this work, hybrid polymer fiber membranes based on polyvinylidene fluoride (PVDF) with graphite flakes were obtained by electrospinning. The morphology of the obtained samples was investigated using SEM microscopy methods, and their crystalline structure was analysed using XRD, Raman, and FTIR methods. Using RFE spectroscopy, it was shown that the addition of graphite leads to ion‐dipole interaction between the carbon surface and the polymer dipoles, changing the ratio of covalent and semi‐ionic bonds on the surface. The catalytic properties investigated during the decomposition of the organic dye methylene blue (MB) demonstrated high piezocatalytic activity of doped membranes and high photocatalytic activity of PVDF/C0.5. It was established that the photocatalytic activity is due to excitonic excitation. [ABSTRACT FROM AUTHOR]

The non‐solvent induced phase separation technology was introduced to formulate titanium dioxide (TiO2)‐hydroxyapatite (HAP) composite modified polyvinylidene fluoride (PVDF) ultrafiltration (UF) membranes, and research was conducted to explore the effect on PVDF UF membrane performance exerted by different addition amounts (0–1.0 wt%) of TiO2‐HAP composite. The results indicated that when 0.3% TiO2‐HAP composite was added, the composite membranes had a through‐channel structure, with a uniform pore structure on the surface, so that they possessed a certainly raised pure water flux. Specifically, in contrast to the pure PVDF membrane, 0.3%‐TiO2‐HAP@PVDF UF membrane exhibited an incremented pure water flux by 59.09%. Besides, TiO2‐HAP@PVDF UF membranes had decreased rejection rate of bovine serum albumin (BSA) together with water contact angle to 58.62% and 70.17°, respectively, compared to the pure PVDF membrane (85.52% & 92.75°), showing good hydrophilicity. Several pure water flux tests on the composite UF membranes revealed that the flux tended to be stable after the 4th test. In summary, the addition of TiO2‐HAP composite is capable of efficiently ameliorating PVDF base membranes from the aspects of microstructure, hydrophilicity, antifouling properties, as well as stability, allowing a good application prospect in actual water treatment. Highlights: The HAP can solve the poor adsorption of TiO2.The TiO2 can improves the interfacial adhesion between HAP and polymer.The TiO2‐HAP composite with excellent stability, corrosion resistance and et al.The TiO2‐HAP@PVDF UF membrane with anti‐pollution performance and stability. [ABSTRACT FROM AUTHOR]

Background: The textile industry represents a great portion of the global industry due to the increase in population and demand for sustainable products. Tons of textile wastewater contain predominantly synthetic complex organic dyes like direct dyes, processing dyes, reactive dyes, etc., making discharge of colored effluents challenging. Textile wastewater treatment is essential to maintain the environmental balance and reduce public health threats. Conventional wastewater treatment methods cannot overcome and decompose these toxic wastes; therefore, numerous modern approaches have been studied and implemented for pollutant degradation to be suitable for environmental disposal. Membranes and photocatalysis have proven their significant effect on the photodegradation of different dyes and the production of pure water for further use in industrial purposes. Short conclusion: This review paper aims to represent a comprehensive review of textile dyeing wastewater treatment by integrating polyvinylidene fluoride (PVDF) and titanium dioxide (TiO2) in a hybrid system named "photocatalytic membrane reactor, PMR". [ABSTRACT FROM AUTHOR]

Piezoelectric nanogenerators have prospective uses for generating mechanical energy and powering electronic devices due to their high output and flexible behavior. In this research, the synthesis of the three-dimensional coral-like BaTiO3 (CBT) and its filling into a polyvinylidene fluoride (PVDF) matrix to obtain composites with excellent energy harvesting properties are reported. The CBT-based PENG has a 163 V voltage and a 16.7 µA current at a frequency of 4 Hz with 50 N compression. Simulations show that the high local stresses in the CBT coral branch structure are the main reason for the improved performance. The piezoelectric nanogenerator showed good durability at 5000 cycles, and 50 commercial light-emitting diodes were turned on. The piezoelectric nanogenerator generates a voltage of 4.68–12 V to capture the energy generated by the ball falling from different heights and a voltage of ≈0.55 V to capture the mechanical energy of the ball's movement as it passes. This study suggests a CBT-based piezoelectric nanogenerator for potential use in piezoelectric sensors that has dramatically improved energy harvesting characteristics. [ABSTRACT FROM AUTHOR]

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Piezoelectrics & Acoustooptics is the property of Piezoelectric & Acoustooptic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Nanomaterials, including nanofibers, have emerged as promising drug delivery systems with a wide range of pharmaceutical applications. In the present study, a nanofiber-based scaffold has been fabricated for ginger oil's formulation. The scaffold formula is composed of ginger oil (encapsulated) within poly(vinylidene fluoride) nanofiber (GIN@PVDF). The scaffold was prepared using electrospinning technique and its structure was confirmed using scanning electron microscopy, FTIR spectroscopic analysis, contact angle measurement, and thermogravimetric analysis. Prepared formula showed higher safety profile against human normal cells (Wi-38), while retained the anticancer effect of the free ginger oil against the Huh-7 liver cancer and the MDA-MB-231 triple-negative breast cancer cells. Moreover, the prepared scaffold showed superior antioxidant potential, as evident by its ability to further activate the transcription of the redox mediator Nuclear factor erythroid-2-related factor 2 (NrF2) compared to the free ginger oil. Furthermore, insignificant difference was observed between the apoptotic effects of GIN-free and GIN@PVDF against MDA-MB-231 cells. Therefore, the novel nanofiber scaffold provides promising potential for the preparation of ginger oil-based pharmaceutical formula for anticancer treatment area. [ABSTRACT FROM AUTHOR]

A novel type of Janus polyvinylidene fluoride/deacetylated cellulose acetate (PVDF/D‐CA) nanofiber membrane with multifunctional application is successfully fabricated by sequential electrospinning. The morphology, chemical composition, surface wettability, oil–water separation performance, and unidirectional liquid transmission capability have been systematically analyzed. It has asymmetric wettability property in air and in liquid systems for its bottom and top sides. It can be used as a water‐removing, or oil‐removing substance for oil–water mixture and emulsion under a harsh environment only under gravity driving force (DF) by simply switching the different sides. It possesses on‐demand water and oil collection ability, and moisture‐wicking performance due to its switchable permeation and unidirectional liquid transmission capability. Its multifunction application can be easy to control by adjusting the thickness of the top and bottom sides through controlling the electrospinning time. Its excellent mechanical property, chemical stability, durability under harsh environment and outstanding anti‐pollution ability endow the membrane with powerful cyclic stability and reusability. [ABSTRACT FROM AUTHOR]

Copyright of Piezoelectrics & Acoustooptics is the property of Piezoelectric & Acoustooptic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Generally speaking, the aerodynamic force generated by each component will hinder the endurance and performance of the UAV. In addition, because PVDF has the characteristics of high flexibility, corrosion resistance and nontoxic, a wind resistance pro-filed sensor based on polyvinylidene fluoride (PVDF) is developed, which can be used to measure the resistance of UAV in different directions. The sensor consists of nine surfaces, which can measure the resistance caused by wind in different directions at the same time. By analyzing the average output voltage collected under different wind speeds and flight states, the resistance of different UAV propellers is estimated. This research is helpful to improve the structure of UAV, reduce the impact of drag, and increase the UAV's endurance time and carrying capacity. [ABSTRACT FROM AUTHOR]

Polyvinylidene fluoride (PVDF) nano-composites are known for the harmonious effect of flexibility, biocompatibility, formability, toughness, higher fatigue life, and piezoelectric properties. Nevertheless, little has been reported on the comparison of mechanical blending (MB) and chemical-assisted mechanical blending (CAMB) of PVDF-BaTiO3-graphene (Gr) nano-composites. This paper reports the comparison of mechanical, thermal, morphological, and 4D properties of PVDF-BaTiO3-Gr nano-composites prepared by MB and CAMB for piezoelectric-based pressure sensors and nanogenerators. In the first stage, feedstock filaments of PVDF-BaTiO3-Gr nano-composites got prepared by MB and CAMB. After this, the effect of blending process parameters on mechanical, thermal, and morphological properties got established on 3D-printed tensile, flexural, and dynamic mechanical analysis samples at optimized settings of fused deposition modeling setup (in the second stage). The results have been supported by Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), X-ray diffraction (XRD), and differential scanning calorimetry (DSC) analysis. The DSC analysis suggested that the PVDF-BaTiO3-Gr nano-composite prepared by MB is thermally more stable than CAMB, as the MB composites absorbed more heat (31.09 J/g) in comparison with the CAMB composite (26.59 J/g). On the other hand, the piezoelectric coefficient (D33) of the dielectric constant of CAMB-based samples was 30.2pC/N, 55, respectively, better than MB (20.1pC/N, 18). Also, results indicated that 3D-printed functional prototypes prepared by CAMB have better mechanical and morphological properties. [ABSTRACT FROM AUTHOR]

Polyvinylidene fluoride (PVDF) nanofibers with cellulose nanocrystals (CNCs) were produced with the electrospinning technique at the CNC loading rates of 0.25, 0.50, 0.75, and 1 wt%. CNCs were obtained with acid hydrolysis of microcrystalline cellulose with 64 wt% sulfuric acid. The material properties of CNCs have been studied with scanning electron microscopy (SEM), transmission electron microscopy, atomic force microscopy, X-ray diffraction (XRD), thermal analysis (TGA), ultraviolet (UV–Vis) spectroscopy, and fourier transform infrared spectroscopy. The PVDF nanofibers with CNCs were produced by the electrospinning technique. The material characterization of neat PVDF and the PVDF–CNC nanofibers were investigated with XRD, TGA, FT-IR, and morphological properties with SEM. The morphological results showed that CNCs were observed as needle-shaped rods and lengths for CNCs were generally in the range of 25–50 nm and 150–300 nm. The crystallinity and crystal size of CNCs were calculated as 75% and 4.8 nm, respectively. CNCs showed the decomposition stages at 100–250 °C and 300–375 °C for the evaporation of the water and decomposition reactions of cellulose, respectively. CNCs exhibited a weak absorbance at 265 nm according to the UV–Vis. As seen in the results of the nanofibers, it was found that CNCs generally decreased the diameters of the nanofibers obtained with the electrospinning when the loading rates of CNCs were raised. The presence of CNCs generally improved the thermal stability of the nanofibers. XRD results showed that crystallinity generally increased with adding CNCs. In FT-IR spectra, any difference was not detected among the PVDF–CNC nanofiber spectra. [ABSTRACT FROM AUTHOR]

Copyright of Piezoelectrics & Acoustooptics is the property of Piezoelectric & Acoustooptic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Polyvinylidene fluoride (PVDF) membranes is a new ferroelectric material exhibiting large piezoelectric properties and has desirable attention in biosensors and the healthcare field. A set of wearable belt was developed using PVDF films of 28 μm as sensitive element and conductive silver as the electrodes. The equipment was designed such that it can sense vibration which could be compatible to those produced by human sleep signal (SS) in a noninvasive way. The prototype of the wearable belt which has 1 × 24 parallel curved slender beams (CSBs) as sensing element using 28 μm thickness PVDF film was fabricated. The element is an assembly of layered media. The base of the sensitive element is a hyperelastic inferior arc polyhedron, on which a PVDF film with silver electrode patches, two 5 μm copper-clad signal interfaces attached to both sides of the PVDF film using conductive adhesive, and a protective surface layer of polyester film for insulation are stacked in sequence. The role of the polyhedron, copper surface end and parallel CSBs design to enhance detection signals, and the capability of the sensor to faithfully detect the SS were experimentally evaluated. Results showed that the new wearable belt (WB) has been manufactured to sense the SS including heartbeat rate (HR), respiration rate (RR) as well as postural signal (PS), and its sensitivity to external mechanical force or vibration is 1.5 times higher than that of a sheet sensitive structure device. All these experimental set-up proposed and developed by us showed the remarkable contribution of the sensitivity and repeatability (98.6%) in SS monitoring depending on signal characteristics such as frequency and amplitude. [ABSTRACT FROM AUTHOR]

Single-use face masks pose a threat to the environment and are not cost-effective, which prompts the need for developing reusable masks. In this study, pressurized gyration (PG) successfully produced bead-on-string polyvinylidene fluoride (PVDF) fibers with fiber diameters ranging from 2.3 μm to 26.1 μm, and bead diameters ranging from 60.9 μm to 88.5 μm by changing the solution parameters. The effect of the solution parameters on the crystalline phase was studied by Fourier-transform infrared spectroscopy (FT-IR), where the β-phase contents of PG PVDF fibers reached over 75%. The fiber morphology and β-phase contents of PG PVDF fibers indicated the potential mechanical and electrostatic filtration efficiency of PG PVDF fibers, respectively. Additionally, the hydrophobicity was investigated by static water contact angle tests, and the PVDF fibers showed superior hydrophobicity properties (all samples above 125°) over commercial polypropylene (PP) single-use masks (approximately 107°). This study supports the notion that the PG PVDF fiber mats are a promising candidate for future reusable face masks. [ABSTRACT FROM AUTHOR]

The extensive growth of telecommunication and electronic devices has led to significant concerns regarding electromagnetic (EM) radiations. Thus, the effect of EM radiations can be reduced by using highly efficient shielding materials. This review aimed to explore the electromagnetic interference (EMI) shielding materials based on polyvinylidene fluoride (PVDF), polyurethane (PU), and polyaniline (PANI) composites. It was found that the composites based on PVDF, PU, and PANI polymers have attracted considerable interest and highly efficient for EMI shielding due to their remarkable properties like lightweight, thermal stability, processing benefits, cheap, tremendous flexibility, and excellent resistance to corrosion. Hence, the PVDF-, PU-, and PANI-based composites are efficient EMI shielding materials. [ABSTRACT FROM AUTHOR]

The Avrami equation modified by Jeziorny, the Ozawa model and the Mo equation combining the Avrami and Ozawa theories were employed to describe the non-isothermal crystallization kinetics of poly(vinylidene fluoride) (PVDF), and PVDF/microcrystalline graphite (MCG) composites. It was found that the Ozawa model failed to describe the non-isothermal crystallization process for PVDF and its composites, while Mo's theory provided good fitting for neat PVDF but did not describe the non-isothermal crystallization well for the PVDF/MCG composites. The addition of MCG promoted the crystallization rate of PVDF, which indicates that MCG acted as a nucleating agent. The absolute values of the effective activation energy of the PVDF/MCG composites calculated by the Kissinger equation, were higher than that of neat PVDF, confirming that MCG acted as a nucleating agent and promoted the crystallization rate of PVDF. [ABSTRACT FROM AUTHOR]

Passive daytime radiative cooling (PDRC) technologies can achieve sub-ambient temperatures by reflecting sunlight and radiating heat to outer space without energy consumption. Conventional PDRC structures, however, suffer from high costs, limited scalability, and poor resistance to pollution. This study presents an optimized Stöber method combined with cetyltrimethylammonium bromide (CTAB) modification to synthesize SiO₂ particles (SiP-C) with nano-synapses surface morphology (30–50 nm) and a broad particle size distribution (100–800 nm). These features facilitate both Rayleigh and Mie scattering, resulting in excellent solar reflectance (97 %) and selective emissivity (0.95). By mixing SiP-C with polyvinylidene fluoride (PVDF), a PDRC coating was fabricated using a simple blade-coating method. The coating, with a thickness of only 143 μm, demonstrated a solar reflectance of 95 % and emissivity of 0.98, achieving a cooling temperature of 10.5 °C below the shielded air temperature under high solar irradiance (981 W/m2) and relative humidity (56.4 %). The SiP-C nano-synapses also imparted hydrophobic properties (contact angle of 142°), enhancing resistance to environmental pollution. The composite PDRC coating thus offers scalability, low cost, high performance, and compatibility for various energy-saving cooling applications. • CTAB-modified Stöber method synthesized highly reflective SiO₂ particles. • SiP-C's nano-synapses and broad particle size showed high solar reflectance. • PDRC paint can be applied to various substrates using a blade-coating method. • PDRC coating achieved 95 % reflectance and 0.98 emissivity at 143 μm. [ABSTRACT FROM AUTHOR]

In response to the significant health threat posed by Traumatic Brain Injury (TBI) resulting from sudden collisions on the head, there is an urgent need for timely assessment and evaluation. With the wide applications of wearable devices in health monitoring, here we report a flexible and wearable smart headband based on a polyvinylidene fluoride (PVDF) sensor to evaluate the impact force and acceleration for TBI assessment. Based on the electromechanical coupling characteristics of PVDF, a lumped parameters model of an equivalent circuit was obtained by a system identification method, which accurately transforms the output signal of the PVDF sensor to the impact force for TBI assessment of focal brain damage. Besides, a drop tower was used to impose different impact intensity levels on a dummy head wearing the smart headband; the results (MSE< 0.018) of transformed impact force show the universal applicability of the model. Moreover, the correlation analysis results show that the impact force has a positive correlation (R>85 %) with impact acceleration at the head center of gravity, which enables the TBI assessment of diffuse brain damage. This smart headband can be used for real-time monitoring of human head impact and has excellent potential for application in medical and sports devices. [Display omitted] • A "kill two birds with one stone" strategy is used to evaluate impact forces on head using a PVDF-based smart headband. • Utilizing a lumped parameter model, the impact force can be determined with MSE< 0.018, enabling brain damage assessment. • A positive correlation between impact force and acceleration at the head center of mass is revealed, enabling TBI assessment. [ABSTRACT FROM AUTHOR]

Thin-film composite (TFC) membranes with a polyamide (PA) active layer are the industry standard in desalination applications. The layer-by-layer (LbL) approach provides more precise control over the properties of this active PA layer. The automated spin-assisted LbL version of this approach then minimizes human error and improves repeatability. To improve durability of these membranes, more robust supports are desired, such as polyvinylidene fluoride (PVDF). The use of the LbL technique on this support requires an interlayer to enable the deposition onto the PVDF. In this case, levodopa was utilized to coat the PVDF prior to deposition of the PA layer. The membranes exhibited moderate permeability and higher selectivity for sodium chloride under typical brackish water conditions compared to commercially available NF membranes. This novel interlayer further expands on the automated spin assisted LbL approach, enabling deposition of PA onto a support. [ABSTRACT FROM AUTHOR]

Polyvinylidene fluoride polymer, LiClO4 salt doped PVDF polymer electrolyte, PVDF/PEG polymer blend and LiClO4 salt doped PVDF/PEG polymer blend electrolyte thin films prepared via solution cast method further these prepared thin films undergone with different characterization techniques i.e. XRD, FTIR, SEM and DSC. XRD and SEM results confirmed that reduction in crystalline nature of PVDF polymer in the presence of PEG polymer and LiClO4 salt. FTIR spectra results revealed that complexation/interaction of LiClO4 salt with polymers. Shifting of glass transition temperature (Tg) and disappearance of melting temperature(Tm) on the DSC curves of PEG and LiClO4 salt doped thin films was observed, which indicated that thermal stability and reduction in crystalline nature of thin films. These results confirmed that LiClO4 salt doped PVDF/PEG thin films may offer higher ionic conductivity for the fabrication of electrochemical cell. [ABSTRACT FROM AUTHOR]

3.8 Mechanical performances of PVDF and PVDF/PEG composite nanofibers The stress-strain plots of the electrospun PVDF and PVDF/PEG composite nanofibrous membranes were presented in Figure 8. 2.4 Electrospinning of PVDF, PVDF/PEG nanofibers membranes The PVDF and PVDF/PEG composite nanofibrous membranes were made on an electrospinning set-up. Graph: Figure 8: Mechanical test of PVDF and polyvinylidene fluoride/polyethylene glycol (PVDF/PEG) fibrous membranes with different mass ratios of PVDF and PEG at 1:0, 4:1, 2:1, and 1:1, respectively. Keywords: composite nanofibers; electrospinning; phase change; polyethylene glycol (PEG); polyvinylidene fluoride (PVDF) EN composite nanofibers electrospinning phase change polyethylene glycol (PEG) polyvinylidene fluoride (PVDF) 181 190 10 03/11/22 20220301 NES 220301 1 Introduction With the rapid scientific progress and economic development, there is an extensive interest in latent heat thermal energy storage (LHTES) and temperature regulation using environment friendly phase change materials (PCMs), with high energy storage density and constant temperature output capability, which have been widely utilized in various fields, such as solar energy systems [[1]], building energy conservation [[3]], smart air-conditioning [[5]], temperature-adaptable greenhouses [[7]], waste heat recovery [[9]], cooling of engines [[11]], thermal insulation [[12]], and homothermal textiles [[13]], [[14]], [[15]]. [Extracted from the article]

The composite nanofiber of polyvinylidene fluoride (PVDF)/polydiacetylene (PDA) is one of the chromic and piezoelectric sensors. In this research, we investigated the effect of adding graphene oxide (GO) nanoparticle to this composite on chromic and piezoelectric properties of the PVDF/PDA/GO. We have also examined the mechanical properties of the PVDF/PDA/GO composite. 5 nanofiber samples with 23%w/v PVDF concentration and 1/3 diacetylene with 0.1, 0.5, 1, 1.5 and, 2.5 percent of GO were prepared via the hybrid electrospinning method. The nanofiber PVDF/PDA, PVDF/GO1% and PVDF were also produced as reference samples. The SEM images of PVDF/PDA/GO nanofibers show that the thinnest nanofibers could be obtained at 1% of GO proportion. In the FTIR test, the growth of β-phase of the sample PVDF/PDA/GO in comparison with PVDF/PDA without GO was obtained. Also, with putting up the samples in the oven of 40 °C and increasing the temperature up to 110 °C, the PVDF/PDA/GO shows same result with PVDF/PDA. In addition, they were thermochromics between 60–70 °C and reversible against the heat at 80 °C. In conclusion, the results show that adding 1% of GO nanoparticle to the PVDF/PDA/GO composite nanofiber can improve significantly the chromic and piezoelectric sensitivity of samples and also the mechanical and physical properties of the composite. [ABSTRACT FROM AUTHOR]

In present work, semi-crystalline polyvinylidene fluoride (PVDF) films of 5 wt%, 10 wt%, and 15 wt% PVDF solution is deposited on the glass substrate by spin coating technique at 500, 1000, and 1500 rpm speed. For deposition of the film, the polymeric solution is prepared by dissolving PVDF powder in the polar solvent of N,N-dimethylformamide solvent. The effect of different PVDF content and spin coating speed on the microstructural evolutions in the produced film is investigated by using FE-SEM, AFM, and FTIR spectrometer. The optical properties of the film are also investigated by the UV-vis spectrometer. [ABSTRACT FROM AUTHOR]

In order to remove 4-nitrophenol from wastewater, a silver-polyamide/polyvinylidene fluoride(Ag-PA/PVDF) composite membrane was prepared. First, poly (methacrylic acid)(PMAA) microspheres were synthesized, then PVDF/PMAA polymer membrane was prepared by blending PMAA with polyvinylidene fluoride (PVDF), then the separation layer was constructed by interfacial polymerization and in-situ loading of Ag nanoparticle catalysts on the membrane surface to obtain the Ag-PA/PVDF composite catalytic membrane. The membrane was characterized by FTIR, XPS, SEM and ICP. The catalytic reduction of 4-nitrophenol by composite membrane was tested. The results showed that the composite membrane was composed of PVDF/PMAA supporting layer and polyamide-Ag nanoparticle catalytic separation surface layer; the catalytic reduction of 4-nitrophenol by composite membrane followed the first-order reaction kinetics and the apparent activation energy was 13.45 kJ/mol; the rate constant of the catalytic reaction increased from 0.062 1 min-1 to 0.101 3 min-1 with the increase of the catalyst load; the rate constant of the catalytic reaction increased from 0.088 9 min-1 to 0.122 1 min-1 with the increase of temperature; the removal rate of 4-nitrophenol by the composite membrane was above 93.5% after 10 cycles, showing good stability. [ABSTRACT FROM AUTHOR]

Polyvinylidene fluoride (PVDF) is a semi-crystalline ferroelectric polymer which can be stabilized in its distinct electroactive polymorphs α and γ by selective processing techniques. In this article, to study the effect of processing temperature and barium calcium zirconium titanate (BCZT) ceramic-doping on PVDF phase stabilization, the pure PVDF and PVDF/BCZT composite films were fabricated by solution-casting and melt-pressing. The Fourier-transform infrared spectroscopy and x-ray diffraction studies showed that the pure PVDF and PVDF/BCZT composite films fabricated by solution-casting possessed the characteristic γ-PVDF peaks while melt-pressing stabilized PVDF mostly in the α-phase. The BCZT ceramic particles were found to have no significant effect on PVDF phase stabilization, but it enhanced the overall crystallinity of polymer matrix. The dielectric studies revealed that the relative permittivity (εr) of γ- and α-PVDF phases in pure PVDF film samples was ≈ 10 and 7.5 (at 120 Hz) respectively. The εr of PVDF/BCZT composite films having 50 wt.% BCZT content synthesized by solution-casting and melt-pressing were estimated to be ≈ 31 and 20 (at 120 Hz), respectively, which was about three times that of pure PVDF film synthesized by the respective technique. The value of loss tangent (tanδ) for pure PVDF films synthesized by solution-cast and melt-press technique were ≈ 0.07 and 0.35 (at 120 Hz) respectively. In temperature-dependent dielectric studies, γ-PVDF showed distinct α-relaxation peak at ≈ 120°C and polymer melting at temperature > 130°C. For α-PVDF, the increase in εr and tanδ was observed during α-relaxation transition at higher temperatures. The dielectric studies indicated that the introduction of BCZT ceramic particles in PVDF matrix increased the εr-value by enhancing the dipolar and interfacial polarizations in composites, while the decrease in tanδ-value was observed due to decrease in molecular dipoles with a decrease in wt.% of PVDF content. These phenomena collectively improved the overall electric properties of ceramic/polymer composites which makes them suitable candidates to explore for flexible electroactive material form. [ABSTRACT FROM AUTHOR]

Polyvinylidene fluoride (PVDF), a material with ferroelectric characteristics, is still extremely topical for the manufacturing of transducers, and different examples, some of which have been actively commercialized since the 1980s, are reported in the literature. In this work, we present a review focused on the PVDF technology for the manufacturing of in-air ultrasonic transducers, which found application in medical robotics, sonar systems, and automation industry (e.g., proximity sensors and obstacle detection). The aim is to provide a comprehensive view on the development of such ultrasonic transducers, highlighting the constructive choices and the advantages/disadvantages in a thorough and concise way. [ABSTRACT FROM AUTHOR]

Summary: Carbon electrodes for aqueous supercapacitors should have extensive surface area for higher energy and surface morphology enabling electrolyte ions to access the entire surface. The multiple micropores below 2 nm enhance the specific surface area, while mesopores of 2‐50 nm allow easy ion transport through porous structure. Here, we synthesize a hierarchical carbon via both a polyvinylidene fluoride precursor directly converting to microporous carbon during pyrolysis and a sol‐gel templating route producing the mesopore. Polytetrafluoroethylene is added to induce mesopore by thermal decomposition. Both the fluorine‐containing polymers autonomously remove the silica template using evolving HF and C2F4 gas during pyrolysis. The dimethylformamide polar solvent helps dissolve both polymers and form alkaline condition beneficial for sol‐gel process. The sol‐gel–processed carbon exhibits wide pore ranges of over 50 nm, leading to surface area of 1230 m2 g−1 with capacitance of 105 F g−1 in neutral Na2SO4. The sol‐gel–route develops the hydrophilic surface, effectively reducing the electrode resistance in aqueous electrolyte and promoting porous surface utilization. The capacitance retention of 78% exhibits at 10‐fold faster rate due to the hierarchically structured pore and hydrophilic surface. Both the energy and power densities are superior to commercial activated carbon with larger area. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Tiangong University is the property of Journal of Tianjin Polytechnic University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this article, polyvinylidene fluoride (PVDF) ferroelectric polymer thin-film-based two axe-head-shaped cantilever-type piezoelectric energy harvester (C-PEH) devices are presented, such as Device 1.1 with ring proof mass and Device 2.1 without ring proof mass for base excitation and tip excitation-based energy harvesting, respectively. These fabricated miniature axe-head-shaped C-PEHs comprising different active areas and volumes are evaluated by both finite-element method (FEM) -based simulations and experimentations. We also present a concept to use these prototypes in a wireless mouse to harvest base and tip excitation-based energy. Device 1.1 made with 96.5-mm3 active volume including an axe-head-shaped C-PEH and 0.72-g ring proof mass produces maximum 7.81- and 594.5-nW power outputs when it was excited by the ${x}$ -axis (direction of normal wireless mouse sliding) and ${z}$ -axis (direction of gravity entailing 0.5-g acceleration) -based vibrations, respectively. Device 2.1 made with 14.8-mm3 active volume comprising only an axe-head-shaped C-PEH produces maximum 9.3391- and 0.0369- $\mu \text{W}$ power outputs when it was excited by a rotary motion due to wireless mouse-wheel rotation and ${z}$ -axis (direction of gravity entailing 0.5-g acceleration) -based vibration, respectively. The experimental results demonstrate excellent performance when compared to the test results of the well-known same active area and volume-based trapezoidal-shaped C-PEHs and other already published similar devices. [ABSTRACT FROM AUTHOR]

A piezoelectric geophone is a vibration transducer that converts mechanical vibrations into electrical signals via the piezoelectric effect. At present, the commonly used sensitive component of the conventional piezoelectric geophone is piezoelectric ceramic (PZT) material, which has low structural flexibility and high natural frequency. This paper reports a piezoelectric geophone based on polyvinylidene fluoride (PVDF) film with a sensitive unit composed of PVDF film and spiral cantilever beam, which can increase the sensitivity and reduce the low-frequency cutoff frequency. Firstly, the PVDF piezoelectric film is introduced, and the sensitive unit with PVDF piezoelectric film and spiral cantilever beam is designed. Secondly, the signal conditioning circuit and the digital module circuit are designed according to the characteristics of the detector and the test environment. Finally, the performance tests and fabrication of the geophone are carried out. The results indicate that the piezoelectric geophone has a stable sensitivity of 230 mV/m/s2 in the range of 4–90 Hz, which are superior to the existing piezoelectric geophone. [ABSTRACT FROM AUTHOR]

In view of the serious membrane fouling problem in the treatment of oil wastewater by ultrafiltration membrane, the polyvinylidene fluoride (PVDF) ultrafiltration membrane modified by gel microspheres was prepared. P(MAAc-co-MAAm) multi-hydrogen bonding self-assembled gel microspheres were synthesized by free-radical polymerization combined with vigorously stirring, and grafted on the surface of carboxylated PVDF membrane through intermolecular hydrogen bonding interactions. The particle size of microspheres was measured by dynamic light scattering particle size analyzer (DLS), the surface morphology of membranes was observed by scanning electronic microscopy (SEM) and atomic force microscopy (AFM), and the performances of membranes were characterized by contact angle test, underwater oil droplet adhesion test and oil-water emulsion filtration test. The results show that the average diameter of gel microspheres is about 248 nm. Water contact angle of the modified membrane is as low as 25.4 ° ± 1.5 °, and the modified membrane has excellent resistance to oil droplet adhesion underwater. The rejection rate of PVDF modified membrane prepared with 40 mL P(MAAc-co-MAAm) gel microspheres suspension to the N-hexane oil-water emulsion with an average particle size of 220 nm is as high as 99.8%. After four oil-water emulsion cycle tests, the flux recovery rate of the modified PVDF membrane is 85.2%, while the one of pure PVDF membrane is only 41.5%. It indicates that the modified PVDF membrane has excellent anti-fouling performance, and separation performance as well. [ABSTRACT FROM AUTHOR]

In this work, the composite nanofibers with energy storage potential were fabricated by means of electrospinning, with the polyvinylidene fluoride (PVDF) as filament-material. The phase change eutectic mixture of myristic acid (MA) and tetradecanol (TD) were used as energy storage material to make the composite nanofibers. The composite nanofibers of PVDF/MA-TD were characterized using scanning electronic microscope (SEM), Fourier transformation infrared spectroscope (FTIR), differential scanning calorimeter (DSC), thermogravimetric analyzer (TGA) and mechanical testing machine. The results demonstrated that the eutectic mixture of MA-TD, with the mass ratio of TD/MA at 7:3, present the melting point of 37.8 °C and latent heat of 155.2 J/g, respectively. Furthermore, there was not any chemical reaction between PVDF and the eutectic mixture of MA-TD, because of the high chemical stability of PVDF. The melt point of composite nanofibers of PVDF/MA-TD was higher than that of pure MA-TD eutectic mixture. The DSC results indicated that the electrospun PVDF/MA-TD composite nanofibers with various MA-TD loadings had suitable phase transition temperatures with the latent heat ranging from about 6 to 77 J/g. Moreover, the considerable thermal energy storage capacity, good thermal stability and mechanical properties made the PVDF/MA-TD composite nanofibers to be the potential materials in the applications of energy storage and thermo-regulating textiles. [ABSTRACT FROM AUTHOR]

In this study, we discussed the characterization and water treatment properties of the newly designed flower type membrane which has multi-bore structures prepared by the thermally induced phase separation process. The flower membrane for water treatment purposes was made of hydrophobic polyvinylidene fluoride polymer. The antifouling characteristics during the water treatment were studied using bovine serum albumin as a model compound and the chemical resistance was evaluated after long-term impregnation in hypochlorous acid (NaOCl) solution to understand the long-term stability of the membranes. Water permeability and mechanical strength of the membranes after prolonged chemical exposure was measured to observe the change in mechanical property and long-term performance of the membrane. Zeta potential measurements were used to find how the surface pollution affected the membrane performance and morphologies of the surface and crosssection of the membrane were confirmed by using scanning electron microscopy. To understand the efficiency of chemicals in the actual process, chemically enhanced backwashing was also carried out using citric acid and sodium hypochlorite in the lab-scale water treatment process. [ABSTRACT FROM AUTHOR]

Highly porous activated carbon is an essential electrode material for high-energy-density supercapacitors, since the electrical charge is stored through electrolyte-ion adsorption on an electrode with high surface area. Here, we report the facile and simple synthesis of an activated carbon with tailored porosity from the blended polymers with different thermal stabilities, i.e., polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE). Through a thermal treatment (900 °C) under inert atmosphere, PVDF is simply transformed into highly microporous (<2 nm) carbon, owing to the release of the combined hydrogen and fluoride. The microporous surface morphology reduces the specific capacitance at high discharging rates. Meanwhile, the PTFE is completely evaporated to the C 2 F 4 gas at 900 °C under an inert environment. The mixed polymer with a specific ratio (PVDF:PTFE = 2:1) is carbonized to porous carbon with a highly accessible surface area. The mesopore (2–50 nm) formed via C 2 F 4 -gas escape from PTFE facilitates ionic transfer to the surface at a rapid discharging rate with the high specific capacitance, i.e., 99 F g−1. Compared with the PVDF-alone derived carbon, the carbon derived from the appropriately mixed precursors exhibits a 19 % higher specific capacitance and increased capacity retention at a 10-fold faster discharging rate. Image 10222 [ABSTRACT FROM AUTHOR]

Copyright of Journal of Tiangong University is the property of Journal of Tianjin Polytechnic University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)