Polyvinylidene Fluoride Composite Films Research Articles

Photoinduced charge generation of nanostructured carbon derived from human hair biowaste for performance enhancement in polyvinylidene fluoride based triboelectric nanogenerator

Carbon nanostructures derived from human hair biowaste are incorporated into polyvinylidene fluoride (PVDF) polymer to enhance the energy conversion performance of a triboelectric nanogenerator (TENG). The PVDF filled with activated carbon nanomaterial from human hair (AC-HH) exhibits improved surface charge density and photoinduced charge generation. These remarkable properties are attributed to the presence of graphene-like nanostructures in AC-HH, contributing to the augmented performance of PVDF@AC-HH TENG. The correlation of surface morphologies, surface charge potential, charge capacitance properties, and TENG electrical output of the PVDF composites at various AC-HH loading is studied and discussed. Applications of the PVDF@AC-HH TENG as a power source for micro/nanoelectronics and a movement sensor for detecting finger gestures are also demonstrated. The photoresponse property of the fabricated TENG is demonstrated and analyzed in-depth. The analysis indicates that the photoinduced charge carriers originate from the conductive reduced graphene oxide (rGO), contributing to the enhanced surface charge density of the PVDF composite film. This research introduces a novel approach to enhancing TENG performance through the utilization of carbon nanostructures derived from human biowaste. The findings of this work are crucial for the development of innovative energy-harvesting technology with multifunctionality, including power generation, motion detection, and photoresponse capabilities.

Improved pyroelectric performances of functionally graded graphene nanoplatelet reinforced polyvinylidene fluoride composites: Experiment and modelling

Polyvinylidene fluoride (PVDF), as a pyroelectric polymer, has great potential applications in electronic devices and sensors. However, the low pyroelectric properties of pure PVDF limit its application. In this work, functionally graded graphene nanoplatelet (FG-GNP) reinforced PVDF composite films are prepared and test for their pyroelectric performance. Apart from experiments, the pyroelectric properties of the films are modelled and analyzed by finite element analysis (FEA), which is verified by the experiments as conducted. It demonstrates that the pyroelectric properties of FG-GNP/PVDF composite films are significantly improved compared to the homogeneous GNP/PVDF composite counterparts. It is found that for the same thickness and amount of GNP added, the increase in the number of layers leads to enhanced pyroelectric properties of the composite films. When the GNP concentration of the layer closed to the surfaces of the FG-GNP/PVDF composite film is higher, the pyroelectric properties and temperature stability of the film are more favorable.

Enhanced dielectric properties of polyvinylidene difluoride composite films by boron nitride nanosheet @ metal organic framework hybrid fillers

Generally, it is hard to simultaneously achieve the enhanced dielectric constant and breakdown strength of polymeric composite by simply introducing fillers into polymers. In this work, a novel hybrid fillers boron nitride nanosheet @ metal organic framework (BNNS@MOF), in which the nanoscale UiO-66-NH2 were epitaxially loaded on layer surface of the BNNSs, was prepared by the hydrothermal reaction. The test results indicate that the BNNS@MOF hybrid fillers were endowed with high breakdown resistance of BNNS and high dielectric constant of UiO-66-NH2. After introducing 1 wt% BNNS@MOF hybrid fillers into polyvinylidene fluoride (PVDF) at the frequency of 102 Hz, PVDF composite films demonstrated a relatively high dielectric constant (ε = 10.7), and energy density (Ue = 6.06 J/cm3) under the high breakdown strength (Eb = 378 MV/m), but low dielectric loss (tan (δ) = 0.039). Compared to PVDF with simply mixed BNNS and UiO-66-NH2 (ε = 12, tan (δ) = 0.061, Ue = 3.14 J/cm3, Eb = 249 MV/m), hybrid fillers showed significant advantages. Our work presented a new idea to construct the PVDF composites with simultaneously enhanced dielectric constant and breakdown strength by introducing hybrid fillers. The hybrid fillers showed promising application in the field of film capacitors.

Cover Image

The cover1 image is based on the Research Article High pyroelectric performances of graphene nanoplatelet reinforced polyvinylidene fluoride composite film by Bowen Zeng et al., https://doi.org/10.1002/pc.27480.image

Retracted: Preparation of Modified Carbon Nanotube Polyvinylidene Fluoride Composite Film and Its Application in Packaging Design

Retracted: Preparation of Modified Carbon Nanotube Polyvinylidene Fluoride Composite Film and Its Application in Packaging Design

High pyroelectric performances of graphene nanoplatelet reinforced polyvinylidene fluoride composite film

AbstractAs a semi‐crystalline polymer with pyroelectric properties, polyvinylidene fluoride (PVDF) has demonstrated great potential in developing smart and multifunctional materials. However, the low level of β phase in pure PVDF restricts its pyroelectric performance and applications. Selecting graphene nanoplatelets (GNP) as the reinforcing filler, this current work pioneeringly investigates the pyroelectric performances of GNP/PVDF composite films subjected to different scenarios. It is found that the addition of GNP can significantly enhance the formation of the β phase in PVDF and the pyroelectric performances of the composite. When the GNP content is 10 wt%, the pyroelectric coefficient of the GNP/PVDF composite film reaches up to 260 μC/m2K, which is about 10 times that of pure PVDF. Parametric study demonstrates that decreasing the thickness of the composite film and increasing the temperature are beneficial to improve the pyroelectric performances. Moreover, the addition of GNPs cannot only enhance the pyroelectric performance, but also improves the thermal stability of the composite film. The work is envisaged to provide guidelines for the design and manufacturing PVDF‐based sensors with improved sensitivity.

Electrospun graphene oxide–polyvinylidene fluoride composite film preparation and application for air filtration

In this work, polyvinylidene fluoride (PVDF) and graphene oxide (GO) composite membranes were fabricated using electrospinning technology for particulate matter (PM) filtration. The preparation conditions like GO oxidation time, electrospinning solution composition, and GO content in the composite film, and the basic properties and filtration performance of PVDF–GO films were systematically analyzed. It was found that GO with lamellar structure was of great benefit to endow the membrane with excellent mechanical properties and particle capture capacity. The as-prepared PVDF–GO membranes with GO addition of 0.6 wt.% exhibited the highest tensile strength and PM filtration efficiency. This work demonstrated that blending GO in PVDF is a feasible modification to fabricate an effective PM filtration membrane.

Study of Nonisothermal Crystallization Kinetics of Unstretched and Uniaxially Stretched Electroactive PVDF Composite Films

AbstractIncorporation of graphene‐based fillers such as graphene oxide (GO) and reduced graphene oxide (rGO) into polyvinylidene fluoride (PVDF) followed by uniaxial stretching can significantly improve their electroactive phase content as well as the dielectric properties. In this study, the nonisothermal crystallization kinetics of unstretched and uniaxially stretched PVDF‐GO and PVDF‐rGO composite films are investigated through differential scanning calorimetry (DSC) at different cooling rates. Avrami‐modified Jeziorney's model is used to understand their crystallization behavior which leads to the nucleation of electroactive crystalline phases in PVDF. Avrami's exponent “n” values in the range of 2–4 are obtained for nonisothermal crystallization of PVDF in different samples which reveal both two‐ and three‐dimensional growth of spherulites in the crystalline region. Kissinger's method is used to calculate the activation energy of crystallization and the results reveal accelerated crystallization of PVDF after addition of GO and rGO fillers followed by uniaxial stretching.

Preparation of Modified Carbon Nanotube Polyvinylidene Fluoride Composite Film and Its Application in Packaging Design

Sustainable design does not emphasize the safety of the ecosystem, but builds a systematic innovation process, taking into account customer needs, environmental benefits, social benefits, and corporate development. This article is based on the preparation of a modified carbon nanotube polyvinylidene fluoride composite film to analyze its application value in packaging design, aiming at analyzing the performance of the modified carbon nanotube and the polyvinylidene fluoride composite film during the preparation process, and applying its various characteristics to the process of packaging design optimization concept. The article is mainly divided into two parts: preparing modified carbon nanotubes and preparing polyvinylidene fluoride composite films. Among them, the photomechanical properties of carbon nanotubes, the relationship between the composition of the composite material and the dielectric properties, the dielectric response and relaxation behavior, the hydrophilicity of the composite membrane, and the membrane separation technology were discussed, and the carbon nanotubes were constructed. Incorporating carbon nanotubes into carbon fiber hybrid materials, and combining carbon nanotubes with polymer materials, works extremely well. The structure model is prepared, the molecular pore size, hydrophilicity, etc. are recorded, and surface modification, chemical modification, blending modification, and other methods are applied to analyze and evaluate the data. The experimental results show that in the application of modified carbon nanotubes and polyvinylidene fluoride composite films and packaging design, the interactive function of toughening modification increases 2.44 points; through enhancement modification, packaging design reduction increases by 2.5 points; and through the compatibilization modification, the functionality of the packaging design has increased by 1.88 points.

Comprehensive Characterization of Solution-Cast Pristine and Reduced Graphene Oxide Composite Polyvinylidene Fluoride Films for Sensory Applications

Pristine and doped polyvinylidene fluoride (PVDF) are actively investigated for a broad range of applications in pressure sensing, energy harvesting, transducers, porous membranes, etc. There have been numerous reports on the improved piezoelectric and electric performance of PVDF-doped reduced graphene oxide (rGO) structures. However, the common in situ doping methods have proven to be expensive and less desirable. Furthermore, there is a lack of explicit extraction of the compression mode piezoelectric coefficient () in ex situ rGO doped PVDF composite films prepared using low-cost, solution-cast processes. In this work, we describe an optimal procedure for preparing high-quality pristine and nano-composite PVDF films using solution-casting and thermal poling. We then verify their electromechanical properties by rigorously characterizing -phase concentration, crystallinity, piezoelectric coefficient, dielectric permittivity, and loss tangent. We also demonstrate a novel stationary atomic force microscope (AFM) technique designed to reduce non-piezoelectric influences on the extraction of in PVDF films. We then discuss the benefits of our measurements technique over commercially sourced piezometers and conventional piezoforce microscopy (PFM). Characterization outcomes from our in-house synthesized films demonstrate that the introduction of 0.3%w.t. rGO nanoparticles in a solution-cast only marginally changes the -phase concentration from 83.7% to 81.7% and decreases the crystallinity from 42.4% to 37.3%, whereas doping increases the piezoelectric coefficient by 28% from = 45 pm/V to = 58 pm/V, while also improving the dielectric by 28%. The piezoelectric coefficients of our films were generally higher but comparable to other in situ prepared PVDF/rGO composite films, while the dielectric permittivity and -phase concentrations were found to be lower.

Electro-Assisted 3D Printing Multi-Layer PVDF/CaCl2 Composite Films and Sensors

Polyvinylidene fluoride (PVDF) films are widely used in sensors for their wide response frequency, good flexibility, low acoustic impedance, and chemical stability. In this work, PVDF/CaCl2 piezoelectric films were prepared by an electro-assisted 3D printing method and used to form a multi-layer composite film sensor. The study found that the addition of CaCl2 can effectively increase the β-phase content in the PVDF film and improve the piezoelectric and dielectric properties of the PVDF composite film sensors. When the content of CaCl2 is 0.15 wt.%, the β-phase content of the PVDF/CaCl2 composite film can reach the highest value of up to 48.47%, and the output voltage response of the sensor is 0.62 V at an input frequency of 10 Hz, 10 V voltage. The output voltage of PVDF composite film sensor with two and three layers is 1.306 and 1.693 times that of a single layer, respectively. The sensitivity of the multi-layer sensors has also been greatly improved.

3D printing of polyvinylidene fluoride composite films with enhanced electroactive beta-phase for flexible wearable pressure sensors

Following the notable rise of three-dimensional (3D) printing in recent years, its use for the fabrication of functional devices derived from piezoelectric polymers such as poly (vinylidene fluoride), PVDF, has become an active area of research. However, there is still a lot to understand about the structure–property-processing relationship regarding the 3D printing of PVDF-based polymers with an enhanced piezoelectric property, which is closely related to the β-phase crystal structure of the polymer. This paper presents the preliminary results of investigations into the extrusion-based 3D printing of poly(vinylidene fluoride-hexafluoropropylene), PVDF-HFP, a PVDF copolymer. Towards the enhancement of the β-phase content of this copolymer, the study analyzed the influence of two fillers in the form of barium titanate (BaTiO3) and untreated activated carbon (UAC) and considered the effect of two printing parameters on the piezoelectric crystalline structure of the PVDF-HFP. First, composite films of the PVDF-HFP with the fillers were formed via the solvent evaporation casting method. From the characterization of the solvent-cast samples using Fourier Transform Infrared Spectrum (FTIR), a composite consisting of 10.55 wt% BaTiO3 and 0.45 wt% UAC with the matrix of PVDF-HFP was found to produce a superior β-phase content (67%) and it was deployed for syringe-based extrusion-assisted 3D printing. Post-fabrication characterization of the extruded samples was carried out to examine the influence of the 3D printing conditions in the form of printing bed temperature (50, 75, 95) and extrusion speed (10, 15, 25). It was found that the combination of a higher printing bed temperature and a low printing speed further enhanced the β-phase content for the PVDF-HFP composites, yielding a β-phase content of 79.6%. Confirmation of the electromechanical/piezoelectric response of the unpoled strips of printed samples revealed a positive correlation between the externally applied pressure on the printed strips and generated voltage.

Preparation and properties of antibacterial PVDF composite thin films

As medical dressings, polyvinylidene fluoride (PVDF) thin films loaded with antimicrobial agents offer excellent wound infection control. In this study, PVDF/tea polyphenol (TPs) and PVDF/TPs/Ag composite thin films were prepared by electrically assisted three-dimensional (3D) printing method. The surface morphology, hydrophilicity, and antibacterial properties of the composite thin films were studied. The results showed that the presence of appropriate amount of TPs promoted the crystallinity and β-phase content of the PVDF thin films, and TPs played an important role in the formation of abundant holes on the surface of PVDF films. It facilitated the deposition of silver nanoparticles on the surface of PVDF thin film and improved the uniformity of their distribution. The Escherichia coli (E. coli) inhibition rate of the PVDF/TPs composite thin film reached 97.22%. The antibacterial activity of this composite thin film improved significantly after the deposition of silver nanoparticles, and the E. coli inhibition rate of the PVDF/TPs/Ag composite thin film was 99.58%.

Long‐Term‐Stable Strong Second Harmonic Generation in Flexible DAST−PVDF Composite Films Realized by the Interface Interactions (Adv. Mater. Interfaces 17/2021)

DAST–PVDF Composite Films In article number 2100485, Xiaomeng Cheng, Xiangdong Xu, and co-workers demonstrate that the interface interactions of the electrostatic interactions and the intermolecular hydrogen bonds between 4-N,N-dimethylamino-4′-N′-methyl-stilbazolium tosylate (DAST) and polyvinylidene fluoride (PVDF) improve the conjugation of p electrons and molecular ordering of DAST, thus making tunable and long-term-stable strong nonlinear optical properties of flexible composite films.

Effective lightweight, flexible and ultrathin PVDF/rGO/Ba2Co2Fe12O22 composite films for electromagnetic interference shielding applications

In this study, we developed a simple and cost-effective solvent film casting method to fabricate ultrathin, flexible and lightweight polyvinylidenefluoride (PVDF)-based composites that provide high electromagnetic interference (EMI) shielding performance. Y-type barium hexaferrite with general formula Ba2Co2Fe12O22 was first synthesized by the sol–gel autocombustion method and then reduced graphene oxide (rGO) was prepared by modified Hummer’s method. The crystal structure, morphology, elemental surface analysis and magnetic properties of the samples were systematically investigated using x-ray diffraction spectroscopy, Fourier-transform infrared spectroscopy, Raman spectroscopy, high-resolution scanning electron microscopy, energy-dispersive x-ray spectroscopy, x-ray photoelectron spectroscopy and vibrating sample magnetometry. Then, the complex permittivity, complex permeability and EMI shielding properties of the flexible PVDF/rGO/Ba2Co2Fe12O22 composite films with two different amounts of Ba2Co2Fe12O22 NP content and a fixed amount of rGO content were investigated using a vector network analyzer. The structural characterizations of the resultant composite films showed the formation of an electroactive β-phase of PVDF with addition of Ba2Co2Fe12O22 nanoparticles and rGO content. The enhancement of the β-phase in the PVDF/rGO/Ba2Co2Fe12O22 nanocomposites was explained from a physicochemical viewpoint. Furthermore, the electrically conductive and magnetic properties of PVDF composite films incorporating rGO and Ba2Co2Fe12O22 NPs exhibited a high EMI shielding effectiveness of 25.63 dB, with an absorption-dominated shielding feature in the 8–12 GHz region. The enhanced absorption was attributed to the electrostatic interaction induced by the β-phase fraction in the PVDF matrix, and subsequently from multiple reflections and magnetic loss originating from the synergetic effect of rGO and Ba2Co2Fe12O22 NPs. This study introduces a low-cost and scalable method for the design of novel, lightweight, flexible and efficient EMI shielding composite films with promising prospects for application in the construction, electronics and aerospace fields.

Long‐Term‐Stable Strong Second Harmonic Generation in Flexible DAST−PVDF Composite Films Realized by the Interface Interactions

AbstractIn this work, novel composite films that are composed of guest 4‐N,N‐dimethylamino‐4′‐N′‐methyl‐stilbazolium tosylate (DAST) and host polyvinylidene fluoride (PVDF) polymer are prepared. Results show that these guest‐host composite films offer the advantages of strong second harmonic generation (SHG), scalability, flexibility, and long‐term stability. The SHG pumped at 800 nm in the poled, thermally annealed, and phase‐matched DAST−PVDF composite films are four orders of magnitude stronger than that of a pure PVDF film, or 300 times stronger than that of a potassium dihydrogen phosphate crystal. Particularly, the interface interactions of the electrostatic interactions and the strong intermolecular hydrogen bonds between DAST and PVDF improve the conjugation of π electrons and molecular ordering of DAST, making the NLO properties of the composites tunable with the ratio of DAST:PVDF. And consequently, the high SHG of the DAST−PVDF composite films can remain stable even after exposure to air for three years.

Piezoelectricity of PVDF composite film doped with dopamine coated nano-TiO2

In this work, dopamine (DA) coated nano-TiO2 (DA@TiO2) modified polyvinylidene fluoride (PVDF) piezoelectric composite films (DA@TiO2/PVDF) with a high β-phase content are successfully fabricated by solvothermal method. The β-phase content of the DA2.0@TiO2/PVDF reaches 84.33%. Furthermore, DA2.0@TiO2/PVDF has the highest crystallinity (Xc) and melting enthalpy (ΔH). Due to synergistic effect between DA and TiO2, the piezoelectric coefficients (d33) and remnant polarization (Pr) of DA2.0@TiO2/PVDF composite films increase by up to 163% and 278% than that of the pure PVDF film, respectively. This work provides a new method to present promise in broadening nanometer preparation technology and improving performance of piezoelectric composites, and contributes to the study on new curved panel energy harvesters for aeroelastic vibration.

Study of enhanced dielectric permittivity of functionalize multiwall carbon nanotube-based polyvinylidene fluoride free-standing film for flexible storage device

We report the dielectric properties of flexible polyvinylidene fluoride (PVDF) and multiwall carbon nanotube (MWCNT) composite films prepared by solution casting route. The Fourier Transform Infrared Spectroscopy (FTIR) and Raman study engraved more dipolar phases within the carboxyl functionalize (f-MWCNT) embedded PVDF composite film. The dielectric permittivity enhances but the dielectric loss reduces for f-MWCNT embedded PVDF film compared to pristine MWCNT (p-MWCNT) embedded film. The dipolar interaction between –CF2 groups in PVDF and –COOH groups of CNT plays a crucial role in enhancing the dielectric constant. The resistance-voltage plot engraves the formation of the hysteresis loop of the nanocomposite film. The enhanced dielectric permittivity and appearance of a hysteresis loop in f-MWCNT embedded PVDF film can be utilized as the flexible storage device material. Apart from the above, the low value of skin depth of the film makes it a promising candidate for designing a flexible electromagnetic shielding membrane.

Ferroelectric BT–PVDF Composite Thick Films for Electrical Energy Storage

Hybrid composites have been elaborated by incorporation of BaTiO3 (BT) inorganic nanoparticles into polyvinylidene fluoride (PVDF) polymer. BT–PVDF composite thick films with different volume fractions of BT (0%, 7%, 15%, and 30%) were deposited by spin-coating onto Pt/SiO2/Si substrates. The effects of the BT inorganic content in the PVDF polymeric matrix on the structural, dielectric, ferroelectric, and energy storage properties were investigated at room temperature. The crystal structure of the samples was identified by X-ray diffraction analysis, and their morphology was observed by scanning electron microscopy. Introduction of BT nanoparticles into the PVDF polymer led to a remarkable enhancement of the dielectric constant value and ferroelectric polarization. Additionally, the abnormal dielectric behavior observed for the composite with 30 vol.% BT nanoparticle volume fraction can be explained by the existence of a Debye relaxation domain at low frequency. Moreover, the stored energy density Wc was enhanced from 2.4 J/cm3 for pure PVDF polymer to 9 J/cm3 for the 30 vol.% BT nanoparticle volume fraction. Such BT–PVDF composite thick films are thus promising materials for the manufacture of electrostatic capacitors for electrical energy storage.

Designing of pressure sensor with polyvinylidene fluoride composite films embedded with nickel oxide for energy harvesting

This paper describes the successful fabrication of specially designed piezoelectric pressure sensor by using poly-vinylidene-fluoride (PVDF) films embedded with nickel oxide (NiO). This PVDF-NiO composite film is prepared using the solvent casting method to improve the electro-active β-phase and enhance crystallinity for various sensing and energy harvesting applications. Various tools were used to analyze changes in the crystalline structure, morphology, and dielectric behavior of PVDF-NiO composite films. Structural characterization and Infrared Spectroscopy affirmed the predominance of electro-active β-phase in the PVDF matrix by adding NiO loadings. XRD studies show that the addition of NiO enhances the crystallinity from 45.62 (for pure PVDF) to 59.01 (1 wt% NiO). FTIR analysis shows that the β-phase fraction for PVDF-NiO film reaches to optimum value from 54% (pure PVDF) to 72% (1 wt% NiO). Micrographs from FESEM illustrates the uniform dispersion of NiO particles within the polymer with little agglomeration at the bottom. The I-V characteristic curves investigate the carrier transport mechanism in the composite films which is predominantly governed by Richardson-Schottky in addition to Poole-Frenkel. The maximum dielectric obtained is 25 with relatively low losses which are thrice than pure PVDF. The increase in AC conductivity at higher frequencies makes this novel composite material suitable for various electronic applications.