Fluoride Composite Films Research Articles

Bi-functional flexible Ag2Se/Polyvinylidene fluoride composite films for thermal energy conversion and electromagnetic interference shielding by solution 3D printing

Developing bi-functional thermoelectric (TE) and electromagnetic interference (EMI) shielding materials is an effective way for the integrated electronic devices to face the accumulated thermal energy and complicated electromagnetic environment. Herein, flexible Ag2Se/polyvinylidene fluoride (Ag2Se/PVDF) composite films were successfully prepared through solution 3D printing and subsequent annealing treatment. As Ag2Se content increased, both the power factor and average total EMI shielding effectiveness (SET) were boosted. When the mass fraction of Ag2Se was 85 wt%, a power factor of 904.6 μW m−1K−2 at 360 K was achieved for the ASP-85 composite film. Meanwhile, this ASP-85 composite film shown the outstanding SET value of 56.1 dB at 52 μm thickness. Flexible Ag2Se/PVDF composite films displayed the excellent thermal energy conversion and EMI shielding capacity.

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.

Effect of pore structure on the piezoelectric properties of barium titanate-polyvinylidene fluoride composite films

Piezoelectric voltage generation in porous barium titanate-poly(vinylidene fluoride) (BT-PVDF) particle-matrix composite films is investigated as a function of PVDF pore structure and porosity. BT-PVDF composite films fabricated via coagulation bath method attain distinct pore structures depending on the ethanol content of the bath. With increasing bath ethanol content, film morphology shifts from higher porosity finger-like cavities to lower porosity mesh-like structures. Finger-like films have a lower Young’s modulus than mesh-like films (224 MPa vs. 368 MPa), but produce higher piezoelectric output voltage when compressed compared to mesh-like films (400 mV vs. 57 mV under 3 N compression). The difference in piezoelectric response is attributed to differences in stress transfer between polymer matrix and ceramic particles. Finite element simulations reveal that finger-like structures produce well-ordered compressive stress while mesh-like structures produce poor stress alignment. The results indicate that improved stress transfer between polymer matrix and ceramic particles can be achieved with well-aligned pore structures, leading to higher piezoelectric output.

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.

Ultra-thin and highly flexible silver fractal dendrite/polyvinylidene fluoride composite film for efficient electromagnetic interference shielding

With the electronic products move towards to flexibility, miniaturisation and high frequency, conductive polymer composites (CPCs) with ultra-low thickness, outstanding electromagnetic interference (EMI) shielding effectiveness (SE) and excellent mechanical property are urgently needed. In this work, silver fractal dendrite/polyvinylidene fluoride (AgFD/PVDF) composite films featured with double structures (defined as two-step films) were fabricated by depositing an AgFD layer followed by the incorporating of PVDF. Thanks to the 3D fractal structures of AgFDs and highly efficient conductive network, the as-prepared two-step films exhibit high electrical conductivity of 4.18 × 104 S·m−1 at only 10 wt% AgFD loading and about 4.18 × 105 S·m−1 at 40 wt% loading. The excellent electrically conductive property endows the two-step films to achieve remarkable EMI SE of 46.8 dB in X-band and 42.7 dB in Ka-band at 10 wt% loading with thickness of 27 μm, and 83.3 and 105.0 dB with thickness of 33 μm as the AgFD loading up to 40 wt%, respectively. The two-step films also show high near-field EMI SE values of 46.9 ∼ 61.4 dB, which fully meets the practical commercial requirements. Additionally, the two-step films possess high flexibility and mechanical strength. Considering the outstanding electrically conductive, EMI shielding performances and excellent mechanical property, the two-step composite films present a huge potential for practical applications as high-efficient EMI protection.

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.

Stable Ultrathin Perovskite/Polyvinylidene Fluoride Composite Films for Imperceptible Multi‐Color Fluorescent Anti‐Counterfeiting Labels

AbstractAs an essential part of information security in the Internet of Things (IoT), fluorescent labels possess a principal portion of anti‐counterfeiting due to its easy fabrication, low cost, and high yield. Here an ultrathin, stable, and patterned multi‐color fluorescent label with perovskite/polyvinylidene fluoride composite film is presented, which registers a resolution of 56.4 dpi and almost maintains its original fluorescent intensity after being immersed in water for 120 h. The variable color of fluorescent labels will improve the anti‐counterfeiting dimensions for the information security due to precise halogen constitutions. The imperceptible fluorescent labels are typically with a thickness of 1.2 um and a weight of 1.2 mg. They can be conformally adhered on the arbitrary curved substrate as the intelligent multi‐color fluorescent anti‐counterfeiting labels for IoT applications.

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.

Enhanced thermoelectric properties of flexible N-type Ag2Se nanowire/polyvinylidene fluoride composite films synthesized via solution mixing

This paper presents inorganic/organic composites, namely, Ag2Se nanowire (NW)/polyvinylidene fluoride (PVDF) films, possessing outstanding thermoelectric power factor and flexibility. The composite film was fabricated through simple solution mixing and drop-casting with various contents of Ag2Se NW (50, 60, 70 and 80wt.%). The Ag2Se NWs were synthesized with solution mixing with as-synthesized Se NWs. The Seebeck coefficient, electrical conductivity, and power factor of the films were valuated; the sample containing 70wt.% Ag2Se NWs showed exceptional durability and enhanced thermoelectric power factor. A maximum power factor of ∼180.6μW/mK2 was reached at 400K. Thus, the proposed Ag2Se NW/PVDF films could be used to realize flexible inorganic/organic thermoelectric devices with good conversion efficiency. In summary, we presented an efficient strategy for designing and synthesizing high-performance inorganic/organic TE composite films by combining the high power factor of an inorganic filler with the high flexibility of a polymer.

Porous flexible polyaniline/polyvinylidene fluoride composite film for trace-level NH3 detection at room temperature

Flexible, highly sensitive, selective, and room temperature ammonia (NH3) sensor based on porous polyaniline/polyvinylidene fluoride (PANI/PVDF) composite film was developed by an in-situ chemical oxidative polymerization process. The obtained flexible PANI/PVDF film showed a three-dimensional and hierarchical porous structure, which greatly enhanced the sensing performance of the PANI film sensor. It exhibited an excellent selectivity to NH3 at 25 °C with 110% response towards 5 ppm. Furthermore, the PANI/PVDF film sensor can detect 1 ppm NH3 (Response = 27%) along with excellent stability and response reproducibility. To 0.2 ppm NH3, the PANI/PVDF showed 6.5% response at 25 °C. Furthermore, it also showed a good linearity relationship between the response and the concentration of NH3. Additionally, the PANI/PVDF film exhibited excellent bending stability, showing very little response value fluctuation at different bending angles. This work shows that the proposed PANI/PVDF film is promising for detecting trace-level NH3 at room temperature, and can be applied in real-time environmental monitoring.

Synthesis and properties of modified polyimide/polyvinylidene fluoride composite films with excellent dielectric properties by adding coupling agent

Modified polyimide (PI)/polyvinylidene fluoride (PVDF) composite films were synthesized by introducing the coupling agent (KH570). Results indicated that the modified composites exhibited high tensile strength, high tensile modulus and excellent thermal properties when the KH570 content increased. The dielectric constant slightly decreased to 4.82 with an increasing amount of KH570, but it was still not low. Noticeably, the dielectric loss of the composite films was small (<0.01, 1 kHz). The breakdown strength significantly increased to 169.65 kV mm−1 when 3 wt% KH570 was added, which was about 173% greater than that of unmodified composites. In addition, the largest value of the maximum energy storage density for the modified composites was 0.651 J cm−3, which was about 6.7 times higher than that of unmodified composites.

Hydrophilic Fluoro‐Functionalized Graphene Oxide / Polyvinylidene Fluoride Composite Films with High Dielectric Constant and Low Dielectric Loss

AbstractA novel and facile method, to synthesize high‐quality fluoro‐functionalized graphene oxide (F‐GO) and polyvinylidene fluoride (PVDF) composite (F‐GO/PVDF) films prepared by solution blending of F‐GO and PVDF in solution was proposed. The fabricated F‐GO/PVDF nanocomposites with different mass fractions exhibited high dielectric constant and low dielectric loss. Meanwhile, Fourier transform infrared spectroscopy and X‐ray photoelectron spectroscopy and raman spectroscopy verified the functional groups in the F‐GO. The microstructure analysis using X‐ray diffraction and field‐emission scanning electronmicroscopy were performed to investigate the morphology of F‐GO and F‐GO/PVDF composite films. The thermal, hydrophilic and electrical characterization properties of F‐GO/PVDF composites were investigated by thermal gravimetric analysis, contact angle, and dielectric constant. These results indicate their potential applications for dielectric devices storage devices.

Mechanical properties and simulation of nanographene/polyvinylidene fluoride composite films

Nanographene possesses unique mechanical and electrical properties. The mechanical properties of nanographene/polyvinylidene fluoride (PVDF) composite films are studied by experiment and simulation analysis in this paper. Different amounts of nanographene/PVDF samples were prepared to obtain general field emission scanning electron microscopy overviews and perform tensile experiments for obtaining the equivalent elastic moduli. Materials Studio was used to establish nanographene microscopic models to obtain linear elasticity data. The digital simulation models were established using ANSYS to conduct the finite element simulation for the equivalent elastic modulus of the composites in different graphene contents and assumptions.Results of the experiments and simulations showed that the equivalent elastic modulus of the composites increases first with increasing graphene content and then decreases after the mass fraction of graphene reaches 10%. The change in the mechanical properties of nanographene/PVDF composites is due to graphene aggregation. The agglomeration phenomenon increases with the increase in graphene.

Structural and Optical Studies on Sol-gel Composites of Nickel-Doped Nanocrystalline Zinc Oxide/Polyvinylidene Fluoride

ABSTRACTNickel-doped nanocrystalline ZnO with three different Ni concentrations was incorporated in polyvinylidene fluoride thin film for obtaining free-standing flexible film by sol-gel technique. The effect of Ni–ZnO loading on the optical and microstructural properties of the Ni–ZnO/polyvinylidene fluoride composite films was studied. X-ray photoelectron spectroscopy and Raman studies were performed to characterize the bonding environment. Fluorine-terminated surface showed a strong F1 s peak located at ∼695 eV arising out of C–F bonds. Existence of β phase of polyvinylidene fluoride along with the presence of ZnO nanocrystals were indicated by Raman studies. Secondary ion mass spectrometry studies indicated the distribution of Ni–ZnO particles in the polyvinylidene fluoride matrix.

Improved lateral heat spreading performance for polyvinylidene fluoride composite film comprising silver nanowire in light-emitting diode

Silver nanowire (AgNW) attracts great attention as a heat dissipation material due to its excellent thermal transfer property which exceeds most traditional heat sink materials.

Nanoparticle Dispersion and Electroactive Phase Content in Polyvinylidene Fluoride/Ni0.5Zn0.5Fe2O4 Nanocomposites for Magnetoelectric Applications

Ni0.5Zn0.5FeO4 ferrite/polyvinylidene fluoride composite films were prepared by a solution method and melt processing. As nanoparticle dispersion and polymer electroactive phase content are some of the key factors for improving magnetoelectric coupling in the composites, the dispersion of ferrite nanoparticles in the polymeric matrix was studied by preparing samples by two alternative dispersion routes: ultrasound and citric acid nanoparticle surfactation. The nucleation of the electroactive beta-phase of the polymer was observed in composites produced by nanoparticle dispersion by ultrasound. This fact avoids the need of stretching composites at elevated temperature in order to obtain the electroactive phase and obtain magnetoelectric composites. By this method, nevertheless, large nanoparticle agglomerates are obtained. Nanoparticle dispersion is largely improved by citric acid surfactation of the nanoparticles. On the other hand, the beta-phase of the polymer is not nucleated due to the modification of the nanoparticle-polymer interaction due to the presence of the surfactant.

Thermal and ferroelectric properties of potassium nitrate: polyvinyl fluoride composite films

The thermal and ferroelectric properties of potassium nitrate (KNO/sub 3/): polyvinyl fluoride (PVF) composite films have been studied. The dielectric constant has been measured as a function of temperature and shows a sharp change during heating and cooling cycles. Differential scanning calorimetry (DSC) has been employed to characterize the phase transitions and corresponding enthalpies in the composite. A good correlation has been found between the transition peak temperatures of the DSC and the transition temperatures of the dielectric measurements in the composite films. The DSC experiments suggest that phase III is retained at room temperature in the composite films. The switching current investigations support the presence of ferroelectric phase in the composite film. The capacitance-voltage (C-V) and conductance-voltage (G-V) characteristics of the composite films exhibit essential butterfly features of a ferroelectric material.