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The Progress of PVDF as a Functional Material for Triboelectric Nanogenerators and Self-Powered Sensors
摘要： Ever since a new energy harvesting technology, known as a triboelectric nanogenerator (TENG), was reported in 2012, the rapid development of device fabrication techniques and mechanical system designs have considerably made the instantaneous output power increase up to several tens of mW/cm2. With this innovative technology, a lot of researchers experimentally demonstrated that various portable/wearable devices could be operated without any external power. This article provides a comprehensive review of polyvinylidene fluoride (PVDF)-based polymers as effective dielectrics in TENGs for further increase of the output power to speed up commercialization of the TENGs, as well as the fundamental issues regarding the materials. In the end, we will also review PVDF-based sensors based on the triboelectric and piezoelectric effects of the PVDF polymers.
关键词： sensor,triboelectric nanogenerator,PVDF
更新于2025-09-23 15:21:01
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Sponge-like Al/PVDF films with laser sensitivity and high combustion performance prepared by rapid phase inversion
摘要： The aluminum-fluorine reaction hold great potential in crippling Al pre-combustion sintering and agglomeration during combustion. Herein, the laser-sensitive Al/PVDF fuel rich films were prepared by employing a sponge-like microvoids structure through phase inversion coupling with micro-segmented flow, displaying the laser power threshold and ignition delay time by less than 4.8 J·cm-2 and 1.57 ms compared to unignited dense Al/PVDF pellet by a 19.6 J·cm-2 laser. The decreased Al atoms plasma electron temperature and a reduced F irons density with the increased Al content, implies a reduction of Al-F reaction ratio. This Al/PVDF films reveal 5 times higher flame propagation rate and mass consumption compared to the vacuum freeze-dried one, contributing to enhanced convective heat transfer in sponge-like microvoids channels. The ambient oxygen and released HF diffusion in microvoids, creating Al-F, Al-O competitive reaction path. The Al-O and Al-F reactions proportions of Al-30, Al-50 and Al-70 were determined by 2: 98, 41:59 and 74.5: 22 after inferring HF and evaporated AlF3 combustion products by several assumption and calculation based on XPS results. The released gaseous H2 and AlF3 from Al droplet surface reduce nano-aluminum sintering. The different reaction paths of Al/PVDF films during combustion and thermal analysis were analyzed.
关键词： Al/PVDF films,Al-F and Al-O competitive reaction,Sponge-like microvoids structure,Phase inversion
更新于2025-09-23 15:21:01
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An approach for broad molecular imaging of the root-soil interface via indirect matrix-assisted laser desorption/ionization mass spectrometry
摘要： Understanding rhizospheric processes is limited by the need for imaging complex molecular transformations at relevant spatial scales within the root soil continuum. Here, we demonstrate a method to enable this analysis by first extracting organic compounds from the rhizosphere onto a PVDF membrane while maintaining their 2D distribution and then imaging the distribution of chemical compounds using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). This approach permitted us to visualize and identify compounds on the root surface and presumed root exudates in the rhizosphere. Within a 1.8 cm x 0.6 cm sampling area of a switchgrass rhizosphere, we could observe at least four chemically distinct zones. Using high performance Fourier transform ion cyclotron MS, we were able to accurately annotate numerous molecules co-localized to each of these zones.
关键词： chemical imaging,PVDF membrane,spatial metabolomics,MALDI,rhizosphere,liquid chromatography
更新于2025-09-23 15:21:01
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Application of Colloidal Precipitation Method Using Sodium Polymethacrylate as Dispersant for TiO <sub/>2</sub> /PVDF Membrane Preparation and Its Antifouling Properties
摘要： Immobilized titanium dioxide (TiO2) nanoparticles on flat sheet polymeric membranes have been found effective for fouling reduction in recent researches. The main challenge in this field is to obtain ultrafine and stable nanodispersions. In this study, composite polyvinylidene fluoride/TiO2 (PVDF/TiO2) ultrafiltration membranes were prepared via phase inversion and colloidal precipitation method. Stable TiO2 suspensions were prepared using sodium polymethacrylate as dispersant and sonication without altering of the coagulation bath pH. The effect of different concentrations of TiO2 nanoparticles in the coagulation bath was also investigated. The membrane morphology (distribution of nanoparticles on the membrane surface) was observed by scanning electron and atomic force microscopy. Properties of the neat and the composite membranes were also characterized using energy dispersive X-ray spectroscopy and contact angle and membrane porosity measurements. The neat and the composite membranes were further investigated in terms of bovine serum albumin rejection and flux decline in cross flow filtration experiments. The results showed that the PVDF/TiO2 composite membrane using dimethylacetamide/triethyl phosphate as solvent and 0.05 g/L of TiO2 in the coagulation bath exhibits improved antifouling properties.
关键词： TiO2 nanoparticles,antifouling properties,ultrafiltration,colloidal precipitation,PVDF membrane
更新于2025-09-23 15:21:01
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Natural Sugar Assisted Chemically Reinforced Highly Durable Piezo-Organic Nanogenerator with Superior Power Density for Self-Powered Wearable Electronics
摘要： Natural piezoelectric material is of increasing interest particularly for applications in biocompatible, implantable, and flexible electronic devices. In this paper we introduce a cost effective, easily available natural piezoelectric material, i.e., sugar in the field of wearable piezoelectric nanogenerator (PNG) where low electrical output, biocompatibility and performance durability are still critical issues. We report on a high performance piezo-organic nanogenerator (PONG) based on the hybridization of sugar encapsulated polyvinylidene fluoride (PVDF) nanofiber webs (SGNFW). We explore the crucial role of single crystal sugar having fascinating structure along with the synergistic enhancement of piezoelectricity during nano-confinement of sugar interfaced macromolecular PVDF chains. As a consequence, the SGNFW based PONG exhibits outstanding electricity generation capability (for example ~100V under 10 kPa human finger impact and maximum power density of 33 mW/m2) in combination with sensitivity to abundantly available different mechanical sources (such as wind flow, vibration, personal electronics and acoustic vibration). Consequently, it opens up suitability in multifunctional self-powered wearable sensor designs for realistic implementation. In addition, commercially available capacitors are charged up effectively by the PONG due to its rapid energy storage capability. The high performance or the PONG not only offers the “battery free” energy generation (several portable units of LEDs and a LCD screen are powered up without using external storage) but also promises its use in wireless signal transmitting systems that widens the potential in personal health care monitoring. Furthermore, owing to the geometrical stress confinement effect, the PONG is proven to be a highly durable power generating device validated by stability test over 10 weeks. Therefore, the organic nanogenerator would be a convenient solution for portable personal electronic devices that are expected to operate in a self-powered manner.
关键词： self-powered electronics,PVDF,organic piezoelectric nanogenerator,high performance and durability,Natural piezoelectric material,sugar
更新于2025-09-23 15:21:01
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[ASME ASME 2018 Conference on Smart Materials, Adaptive Structures and Intelligent Systems - San Antonio, Texas, USA (Monday 10 September 2018)] Volume 1: Development and Characterization of Multifunctional Materials; Modeling, Simulation, and Control of Adaptive Systems; Integrated System Design and Implementation - Parametric Design of a Soft Gripper Actuated Using the Electrostrictive PVDF-Based Terpolymer
摘要： Nowadays, soft grippers, which use compliant mechanisms instead of stiff components to achieve grasping action, are being utilized in an increasing range of engineering fields, such as industry, medical care and biological sample collection, for their material selection, high conformability and gentle contact with target objects compared to traditional stiff grippers. In this study, a three-fingered gripper is designed based on a simple actuation mechanism but with high conformability to the object and produces relatively high actuation force per unit mass. The electrostrictive PVDF-based terpolymer is applied as the self-folding actuation mechanism. Finite element analysis (FEA) models are developed to predict the deformation of the folded shape and grasping force of the gripper with two grasp modes, i.e. enveloping grasp and parallel grasp. The FEA models achieved good agreement with experiments. Design optimization is then formulated and a parametric design is conducted with objectives to maximize free deflection and blocked force of the gripper. The design variables are the thicknesses of the active and passive materials, and the nature of the passive layer. It is found that there exists an optimal terpolymer thickness for a given scotch tape substrate thickness to achieve maximum free deflection, and the blocked force always increases as either thickness of terpolymer or scotch tape increases. As the length of the notch increases, free deflection also increases due to more pronounced folding behavior of the actuator, but the blocked force decreases since the actuator is less stiff. The tradeoff between free deflection and blocked force is critical for the final decision on the optimal design for a particular application.
关键词： soft grippers,design optimization,electrostrictive PVDF-based terpolymer,parametric design,finite element analysis
更新于2025-09-23 15:21:01
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Study on the Mechanism of Ultrasonic Power Measurement Sensor based on Pyroelectric Effect
摘要： PVDF pyroelectric sensor has been widely applied in many fields, such as intruder alarm. Nowadays, this sensor shows a potential for ultrasonic power measurement. However, the transformation mechanism between the acoustic and pyroelectric signals has not been particularly studied until now. In this paper, a physical model was introduced for theoretical study of the mechanism of energy transformations. In addition, a simulation program based on finite-element analysis method was built up for analyzing the ultrasound propagation characteristics and the temperature rise on the PVDF, as well it predicted the waveform and amplitude of the generated pyroelectric signal. Besides that, a PVDF pyroelectric sensor was fabricated and used for acoustic power measurement experiment. Finally, the experiment and simulation results were compared, confirming that the physical model is suitable for pyroelectric sensor characteristics analysis. It can also provide useful suggestions for the design and fabrication of PVDF pyroelectric sensors with high sensitivity.
关键词： ultrasonic power,PVDF,finite-element analysis,pyroelectric sensor
更新于2025-09-19 17:15:36
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Optimized Polyvinylidene Fluoride Nanofiber Webs for Flexible Energy Harvesters
摘要： This work reports the process optimization of various electrospinning parameters to fabricate polyvinylidene fluoride based piezoelectric flexible nanofiber webs for passive sensing and energy harvesting applications. Process parameters like electrospinning voltage and drum speed have been taken into consideration while optimizing the electrospun nanofiber webs for maximizing their piezoelectric property. Finally, the optimized recipe is used to fabricate a flexible PVDF nanofiber energy harvester to demonstrate the energy harvesting capability of such nanofiber webs.
关键词： nanofiber,electrospinning,polyvinylidene fluoride (PVDF),piezoelectricity,sensor
更新于2025-09-19 17:15:36
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Core–shell structured poly(vinylidene fluoride)- <i>grafted</i> -BaTiO <sub/>3</sub> nanocomposites prepared <i>via</i> reversible addition–fragmentation chain transfer (RAFT) polymerization of VDF for high energy storage capacitors
摘要： Core–shell structured poly(vinylidene fluoride)-grafted-barium titanate (PVDF-g-BaTiO3) nanocomposites were prepared by surface-initiated reversible addition–fragmentation chain transfer (RAFT) polymerization of VDF from the surface of functionalized BaTiO3 nanoparticles. The ceramic fillers were first surface-modified with xanthate functions to further allow the RAFT grafting of VDF. A series of structured core shells were synthesized by tuning the feed [initiator functionalized nanoparticles]0 : [monomer]0 ratio, varying from 3 to 5, 10 and 20 wt%. Fourier transform infrared spectroscopy (FTIR), high resolution magic angle spinning (HRMAS) NMR and thermogravimetric analysis (TGA) confirmed the successful surface functionalization of the ceramic filler and the grafting of the PVDF shell onto the surface of the BaTiO3 cores. Transmission electron microscopy results revealed that BaTiO3 nanoparticles are covered by thin shells of PVDF, with thickness varying from 2.2 to 5.1 nm, forming a core–shell structure. HRMAS 19F indicated a grafting of 39–50 units of VDF. X-ray diffraction measurements together with FTIR measurements revealed that PVDF was present in the α form. Thermal properties also indicated that the addition of a small amount of the BaTiO3 filler to the PVDF matrix increased the melting temperature from 168 °C for neat PVDF to 173 °C for PVDF-g-BaTiO3 (20 wt%) and decreased the crystallinity of PVDF from 47% to 21%.
关键词： Nanocomposites,Core-Shell Structure,BaTiO3,PVDF,RAFT Polymerization,Polymer Chemistry,Dielectric Materials
更新于2025-09-19 17:15:36
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TiO2 coated on PVDF membrane for dye wastewater treatment by a photocatalytic membrane
摘要： This work investigated the membrane modi?cation to increase hydrophilicity aiming for application in a photocatalytic membrane. The modi?ed poly(vinylidene ?uoride) (PVDF) ?at sheet membrane was coated with titanium dioxide (TiO2). The chemical and physical changes of membranes were characterized by contact angle, SEM and porosity. The results found that TiO2 successfully modi?ed the PVDF membrane by decreasing the contact angle from 127.1° to 114.3° on increasing the TiO2 concentration from 0.1 to 1.0 g/L. The contact angles were decreased with the increase of coating time. The water permeation after PVDF membrane modi?cation decreased compared with the original membrane, whereas water ?uxes increased with the increase of TiO2 concentration. TiO2 particles were observed on the membrane surface while the porosity of the membrane coated with TiO2 decreased. The optimum condition of membrane coating was obtained at 1.0 g/L of TiO2 and 60 min of coating time. The decolorization of RB 19 by photolysis and photolysis followed by ?ltration was less than 10%; in contrast, the decolorization of RB 19 by photocatalytic oxidation was as well as a photocatalytic membrane for 60 min. The TiO2 photocatalytic membrane is a feasible technology for RB 19 decolorization in wastewater.
关键词： dye,wastewater treatment,PVDF,membrane modi?cation,photocatalytic membrane
更新于2025-09-19 17:15:36