PVDF Nanocomposites Research Articles

Facile preparation and enhanced electromagnetic wave absorption properties of Fe3O4 @PVDF nanocomposite

Fabrication and investigation of microwave absorbing materials have been widely explored to mitigate the emerging EM pollution. In this study, we prepared magnetite (Fe3O4) nanoparticles via a rare facile sol–gel method followed by a calcination process. Then, Fe3O4 and polyvinylidene fluoride (Fe3O4@PVDF) nanocomposite were prepared and the electromagnetic wave absorption (EMWA) properties were studied using the finite element method. Characterization techniques employed in this study include; X-ray diffraction, Fourier-transform infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM), Field emission scanning electron microscopy (FESEM) and Transmission electron microscopy (TEM). The microwave absorption properties of Fe3O4@PVDF were studied at the X-band (8.2–12.4 GHz) and Ku-band (12.4–18 GHz) frequency range. The Fe3O4@PVDF nanocomposite displayed minimum reflection loss of −62.7 dB at 16.9 GHz for 3.5 mm thick sample. These outstanding EMWA coefficients could be attributed to favorable impedance match from outstanding dielectric and magnetic loss mechanisms.

Enhanced dielectric properties and energy storage density of PVDF nanocomposites by co-loading of BaTiO3 and CoFe2O4 nanoparticles

Dielectric polymer-based nanocomposites with high dielectric constant and energy density have attracted extensive attention in modern electronic and electrical applications. Core-satellite BaTiO3-CoFe2O4 (BT-CF) structures with a BT core of ~ 100 nm and CF satellites (~ 28 nm) on the surface of the BT particle were prepared. The dielectric properties and energy storage density of PVDF nanocomposites were enhanced by BT-CF heterostructures at a small loading of CF nanoparticles. Compared to the general adopted BT/PVDF composites, the dielectric constant can be effectively improved with no additional loss by introducing a small amount of CF nanoparticles to the BT/PVDF composite. Moreover, the energy density and efficiency of the BT/PVDF nanocomposites were also improved by the small loading of CF. The discharged energy density of the BT-CF/PVDF nanocomposites with 7 wt.% CF nanoparticles showed that the maximal energy density value is 5.60 J/cm3 at the electric field of 263 kV/mm. The results showed that the small amount of CF nanoparticles has beneficial effects on enhancing the dielectric constant and energy storage of the BT/PVDF nanocomposites.

Gas Sensing and Power Harvesting Polyvinylidene Fluoride Nanocomposites Containing Hybrid Nanotubes

Gas sensing properties at room temperature and energy harvesting performances are realized for the polyvinylidene fluoride (PVDF) nanocomposites containing titanium dioxide (TiO2) nanotubes grown in the presence of carbon nanotubes (CNT). While hydrothermal reaction is practiced for the development of TiO2/CNT hybrid nanotubes, spin coating is done for the nanocomposite films to be deposited on sensing electrodes. Influence of various filler concentrations and the synergistic combination of fillers on the sensing characteristics are studied by recording the response times and the stability of the results. Upon exposure to liquefied petroleum gas, the PVDF/TiO2-CNT (2.5 wt.%) gas sensor shows a sensing response of 0.45 s (400 ppm LPG), approximately nine times higher than the composite containing 2.5 wt.% of TiO2 or 2.5 wt.% CNT. The piezoelectric response of the samples is also recorded and correlated with the synergistic influence of the filler materials. The current study can stimulate a good trend in fabricating self-powered gas sensors from PVDF nanocomposites.

Magnetically influenced dielectric and electrical transport of inorganic–organic polymer-based hybrid nanocomposites

Polymer-based hybrid nanocomposites of [Formula: see text]-([Formula: see text]) poly(vinylidene fluoride) (PVDF) ([Formula: see text], 0.6 and 0.7) have been prepared through low-cost chemical reaction process. The improvement of dielectric properties in polymer-based hybrid [Formula: see text]–PVDF nanocomposites can be utilized to make a suitable memory storage device. Surface modified [Formula: see text] (LFO) nanoparticles are well distributed inside the polymer resulting in improved dielectric constant and reduced dielectric loss. The study of complex and modulus impedance spectroscopy (IS) shows some interesting results for an influence of grain and grain boundary effects of electrical conductivity attributing the non-Debye type phenomena. The change of relaxation frequency with an applied magnetic field is ascribing the spin-dependent mechanism of electrical transport at grain boundaries (GBs). The fitting of Nyquist plot attributes the magnetic domain wall containing GB’s pinning center in the system. The higher concentration of filler LFO nanoparticles shows maximum values of dielectric constant assigning the Maxwell–Wagner–Sillars (MWS) polarization. The current study is focused towards the query to learn the complete study of magnetic field dependence electrical and dielectric properties in a system holding an excessive potential for a capable candidate for industrial applications.

Silica fillers for enhancement of dielectric properties of poly(vinylidene fluoride) and its copolymer

Poly(vinylidene fluoride) (PVDF) based polymers are known to exhibit outstanding piezo-, pyro-, ferro-, and dielectric properties owing to their structural β-phase. In this work, the prospect of enhancement of dielectric properties of PVDF and poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-hfp) polymers has been explored by increasing their β-phase through incorporation of porous and non-porous silica nanoparticles. Polymer films, both in pure and nanocomposite forms, were prepared using a simple solution casting technique. FTIR-ATR spectroscopic analyses of the films revealed increased proportion of β-phase in the polymer nanocomposite films containing silica nanoparticles, compared to the pure polymer films. X-ray diffraction analysis also confirmed a higher β- to α-ratio in nanocomposite films than in pure films. The transformation is considered to occur due to interaction between surface of negatively charged silica nanoparticles and –CH2 group of the polymer which has a positive charge density. Electrochemical impedance spectroscopic measurements corresponded with the increased β- to α-ratio, as the nanocomposite films exhibited higher dielectric constant than the pure films. Mesoporous silica incorporated films even showed higher β- to α-ratio and dielectric constant than non-porous silica incorporated films which may be brought about by the presence of pores in the nanoparticles, which increases the surface area available for interaction with the polymers as well as provides a confined environment favouring the interaction. Thus, this work suggests the possible benefit of silica fillers in preparing nanocomposites of PVDF and its copolymer with enhanced dielectric properties, to be employed in the development of smart materials and in various other applications.

Lightweight, flexible NiO@SiO2/PVDF nanocomposite film for UV protection and EMI shielding application

A series of silica coated nickel oxide nanoparticles incorporated PVDF nanocomposite films have been successfully prepared by solution casting method and the dielectric properties along with EM shielding hasalso been studied. Higher loading of the well-dispersed NiO@SiO2 nanoparticles inthe PVDF matrix leads to the increment of the effective surface area resulting enhancement of the dielectric and ferroelectric properties of the nanocomposite films. The nanocomposite films successfully block the harmful UV radiations. The sample PSNO15 (for 15 wt% loading of the NiO@SiO2 nanoparticles can almost completely block the UV radiation. As the effective surface area and the interfaces are increased due to the SiO2 coating of the NiO nanoparticles, the electromagnetic waves are reflected and scattered for multiple times from these interfaces. These NiO@SiO2/PVDFnanocomposite films are proposed to be used as UV and EMI shielding technology to get rid of EM hazards of the human civilizations.

Enhanced pyroelectric and piezoelectric properties of PVDF – BaTiO3 nanocomposites layered samples

The triple-layered polyvinylidene fluoride (PVDF) and barium titanate (BaTiO3) nanocomposites were prepared using sol-gel method. The structure of polymer is often complex after introducing the nanoparticles. Such properties of BaTiO3 nanoparticle filled PVDF nanocomposites have been investigated by X-ray diffraction and Fourier-transform infrared (FTIR) spectroscopy. XRD and FTIR result indicate the significant improvement in structural morphology of triple layered polymer nanocomposite. Pyro and piezoelectric result also shows the improvement in pyroelectric and piezoelectric coefficients, which is due to enhancement of β-phase.

Mechanical and wear behaviour of poly(vinylidene fluoride)/clay nanocomposite

Poly(vinylidene fluoride) (PVDF)/organically modified nanoclay composites using different amount of nanoclay have been prepared through solution route. The structural changes are determined through X-ray diffraction and Fourier transform infrared spectroscopy studies, which show the transformation from α to β-phase crystallization in presence of nanoclay. Polarised optical microscopic images show the changes of spherulite pattern into mesh like pattern in presence of nanoclay. Modulus of PVDF-nanocomposite increase with increasing the nanoclay content up to 4 wt.% and then slightly decreases under uniaxial tension and the improvement in mechanical responses are fitted with theoretical models. Tribological behaviour of PVDF nanocomposites is evaluated and found that nanoclay content upto 4 wt.% is effective in decreasing the wear and coefficient of friction of PVDF. Similarly, hardness of the nanocomposites also increases for clay content upto 4 wt.%. The nanoclay is working as reinforcing agent for PVDF and is improving its mechanical and frictional properties.

Enhanced dielectric properties of PVDF nanocomposites with modified sandwich-like GO@PVP hybrids

ABSTRACTHerein, graphene oxide (GO) nanosheets coated with insulated polyvinyl pyrrolidone (PVP) were integrated into poly(vinylidene fluoride) (PVDF) to investigate the effects of the insulating PVP shell, loading, and its reaction time on the dielectric properties of the nanocomposites. Compared with the pristine GO/PVDF, the GO@PVP/PVDF nanocomposites show an improvement of the filler dispersion, and significantly suppressed conductivity and loss. Activation energies of GO/PVDF and GO@PVP/PVDF nanocomposites are calculated as 1.247 eV and 0.435 eV, respectively, indicating that the presence of PVP layer on the GO surface reduces the relaxation activation energy and makes the relaxation occurrence at low temperatures.

Facile preparation and properties of polyvinylidene fluoride dielectric nanocomposites via phase morphology control and incorporation of multiwalled carbon nanotubes conductive fillers

ABSTRACTA novel PVDF dielectric nanocomposite was achieved by controlling phase morphology and incorporating conductive fillers simultaneously, and the mechanical, thermal, dielectric properties of the resultant dielectric nanocomposites were investigated. Mechanical analysis showed that incorporation of modified MWCNTs (MWCNTs‐COOH) in the PVDF nanocomposites resulted in significant improvements on the tensile strength (Ts) and elasticity modulus (Em). When the filler content was 12 wt%, the Ts of MWCNTs‐COOH/PVDF could reach 64.6 MPa. XRD test showed that the addition of MWCNTs‐COOH and MWCNTs promoted the formation of β‐phase of PVDF. DMA analysis showed that the glass‐transition temperature of the PVDF nanocomposites slightly increases on loading of original MWCNTs and this effect was more pronounced on loading MWCNTs‐COOH. The dielectric property analysis showed that the original MWCNTs were more likely to form local conductive networks in the PVDF matrix, promoting the electron displacement polarization, and improving the dielectric constant. When the contents of MWCNTs was 12 wt%, the percolation threshold was obtained and the dielectric constant (ε′) reached 286, which was 36 times of pure PVDF. Our work provides a simple way to fabricate polymer blends with excellent dielectric performances, good mechanical properties as well as good processing capability but low cost. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48463.

Enhanced electromagnetic wave absorbing nickel (Oxide)-Carbon nanocomposites

Both NiO-carbon and Ni/NiO-carbon nanocomposites with a dual-configuration were successfully obtained via annealing nickel-carbon precursor under air and N2, respectively. For the NiO-carbon composites, the dual configurations were NiO nanoparticles incorporated in porous flower-like carbon materials and NiO nanoparticles anchored porous carbon microspheres. In the case of Ni/NiO-carbon composites, the dual configurations consisted of Ni/NiO nanoparticles distributed in the carbon flowers and Ni/NiO nanoparticles anchored on the porous carbon microspheres. Amazingly, an ultra-low amount (such as 2 wt%) of the NiO-carbon and Ni/NiO-carbon composites was introduced into the polyvinylidene fluoride (PVDF), the nanocomposites exhibited superior microwave absorption properties. The enhanced microwave absorption ability originated from the synergism consisting of dipole polarization, interfacial polarization, magnetic loss including natural resonance and exchange resonance, as well as dual-configuration contribution (impedance match, point discharge, multiple reflections and scattering). These PVDF nanocomposites filled with dual-configurations of NiO-carbon and Ni/NiO-carbon have been highlighted to be more competitive microwave absorbers in terms of lightweight, strong absorption and ultra-low filler amount.

Black phosphorus-based polyvinylidene fluoride nanocomposites: Synthesis, processing and characterization

In this study, the polyvinylidene fluoride (PVDF) nanocomposites were produced based on the few-layers Black phosphorus nanosheets (BP) via the liquid exfoliation method, and at different BP nanofiller contents (1, 2.5 and 5 wt%). A masterbatch with 5 wt% of BP was prepared by solution blending followed by melt compounding process to elaborate the different nanocomposites and compression molding to molding all samples. The characterization of the nanocomposites in terms of X-ray diffraction, infrared spectroscopy, and scanning electron microscopy confirmed that BP nanosheets were successfully prepared. The nanocomposites were characterized in terms of structural, thermal, electrical, and mechanical performances. The thermal stability of neat PVDF was found increased with 5 wt% of BP nanofillers addition. For the same concentration, the electrical conductivity was sharply increased from 3.3 e−14 to 5 e−11 S/cm. Similarly, Young's modulus value was found increased by 56% as compared to the neat matrix. BP nanofillers appear to be a good alternative to elaborate new polymer nanocomposites with improved performances.

Suppressed loss tangent and conductivity in high-permittivity Ag-BaTiO3/PVDF nanocomposites by blocking with BaTiO3 nanoparticles

The novel concept of combining Ag–deposited BaTiO3/poly(vinylidene fluoride) (PVDF) is proposed using a three–phase composite system employing various sizes of BaTiO3. A mixture of 80 vol% PVDF–20 vol% nanosized BaTiO3 (BT(nm)) particles was designed as a polymer–based matrix, which incorporates Ag–deposited micro–sized BaTiO3 (BT(μm)) hybrid particles. Interestingly, the dielectric permittivity at 103 Hz of the Ag–BT(μm)/PVDF–BT(nm) composites significantly increased from 114.0 to 165.2 with as the filler volume fraction increased from fAg–BT(μm) ≈ 0.4 to 0.5. Concurrently, the conductivity and loss tangent (tanδ < 0.09) were effectively suppressed compared to that of the PVDF–BT(nm) matrix (tanδ ≈ 0.31). The BT(nm) particles in Ag–BT(μm)/PVDF–BT(nm) composites partially inhibited the formation of conduction pathways in the PVDF polymer, retaining low values of the conductivity and loss tangent. Without BT(nm) particles, the dielectric permittivity of the Ag-BT(μm)/PVDF composite with fAg–BT(μm) ≈ 0.4 was only 68.6. Thus, the BT(nm) particles gave rise to shorter interparticle distances between the filler particles and increased the total interfacial areas (i.e., Ag–PVDF, Ag–BT(μm), Ag–BT(nm), and BT(nm)–BT(μm) interfaces), and hence the dielectric permittivity.

Enhanced dielectric properties of PVDF/E-MA-GMA/c-MWCNTs composites with a ‘Sea-Island’ structure

Carboxyl functionalized multiwall carbon nanotubes (c-MWCNTs) were compounded with poly(vinylidene fluoride)/ethylene-methyl acrylate-glycidyl methacrylate terpolymer (PVDF/E-MA-GMA) blends to prepare nanocomposites through melt blending method. The ‘sea-island’ structure composites formed on account of the immiscibility between poly(vinylidene fluoride) and ethylene-methyl acrylate-glycidyl methacrylate at the weight ratio of 90:10. c-MWCNTs were selectively located in ethylene-methyl acrylate-glycidyl methacrylate island phase because of the chemical reactions between the carboxyl groups of c-MWCNTs and the epoxy groups of ethylene-methyl acrylate-glycidyl methacrylate. The ‘sea-island’ morphology facilitated the improvement of dielectric properties for the poly(vinylidene fluoride) nanocomposites. A high dielectric constant of 1286 was obtained for PVDF/E-MA-GMA/c-MWCNTs nanocomposite with 2.5 wt% c-MWCNTs at 1 kHz, which was about 100 times than that of pure PVDF. In addition, the tan delta was suppressed effectively to 2.2. Therefore, this strategy indicates the ‘sea-island’ morphology can enhance the dielectri properties of PVDF nanocomposites because of the confinement of c-MWCNTs in the island phase.

Enhanced dielectric permittivity and suppressed electrical conductivity in polyvinylidene fluoride nanocomposites filled with 4,4′-oxydiphenol-functionalized graphene

Plastic film capacitors suffer from low charge storage capacity due to the low dielectric constant of the polymer (<10). We have devised a polyvinylidene fluoride (PVDF) composite film filled with small graphene oxide (GO) sheets that have aromatic molecules attached to their surfaces. The use of 4,4′-oxydiphenol molecules to functionalize graphene sheets is found to have a remarkable effect on enhancing the dielectric permittivity as well as reducing the electrical conductivity of the nanocomposite. When under an electric field, these molecules with an angled molecular geometry act as aligned electric dipoles to largely enhance the dielectric permittivity of the composite, reaching a level two orders of magnitude higher than that of the counterpart filled with blank graphene sheets. Also, the aromatic molecules on the graphene surface act as resistive barriers that block charge transfer between interconnected graphene sheets. As a consequence, the electric conductivity of the composite can be decreased by two orders of magnitude. The PVDF composite filled with functionalized graphene shows a percolation threshold of 13 wt% and a high dielectric constant of 1091 at 100 Hz at this point.

Microscopic Origin of Piezoelectricity in Lead-Free Halide Perovskite: Application in Nanogenerator Design

In this work, we report a lead-free hybrid halide perovskite system with a very high piezoelectric charge density for applications in nanogenerators. We use materials engineering by incorporation of formamidinium tin iodide, FASnI3, in a soft polymer (polyvinylidene fluoride, PVDF) matrix and demonstrate high-performance large-area flexible piezoelectric nanogenerators. This is achieved by using self-poled thin films of a FASnI3:PVDF nanocomposite. The fabricated devices show an output voltage up to ∼23 V and power density of 35.05 mW cm–2 across a 1 MΩ resistor, under a periodic vertical compression, with a release pressure of ∼0.1 MPa. Measured values of the local piezoelectric coefficient (d33) of these films reach up to 73 pm/V. We provide the microscopic mechanism using first-principles calculations, which suggest that a soft elastic nature and soft polar optic phonons are responsible for the high piezoelectric response of FASnI3. Our studies open up a route to high-performance nanogenerators using a...

Surface modification of GO by PDA for dielectric material with well-suppressed dielectric loss

To suppress the high dielectric loss of graphene oxide (GO)/poly(vinylidene fluoride) (PVDF) while maintaining high dielectric constant (high- k) near the percolation threshold, in this study, GO nanosheets coated with polydopamine (PDA) were integrated into PVDF to investigate the effects of the PDA shell and its concentrations on the dielectric properties of the nanocomposites. The results indicate that the dissipation factor and conductivity of the GO@PDA/PVDF are significantly suppressed to very low values compared with the pristine GO/PVDF composites, attributable to the PDA interlayer between the GO nanosheets which prevents them from direct contact with each other and remarkably reduces the leakage loss. Furthermore, activation energies of the GO/PVDF and GO@PDA/PVDF composites were calculated as 1.247 and 0.884 eV, respectively, indicating that the presence of PDA interlayer reduces the relaxation activation energy and makes the relaxation occur at low temperature for the GO@PDA/PVDF. The prepared GO@PDA/PVDF nanocomposites with high- k but low loss have potential applications in microelectronic engineering.

Multi-layered stack consisting of PVDF nanocomposites with flow-induced oriented MWCNT structure can supress electromagnetic radiation

Polymeric nanocomposites have emerged as a potential material in the electronic world owing to its numerous advantages like ease of processing, design flexibility, light-weight, ease of embedding and integrating with the existing production line. Given the surge in electronic components, electromagnetic interference, which severely impairs the reliability of precise electronic devices, has emerged as a new challenge. Hence, technologically, viable design is the need of the day. However, the high concentration of fillers required to achieve the desired properties still remains a challenge with respect to the design of functional polymeric nanocomposites. In this context herein, we report as to how flow induced distribution of multi-walled carbon nanotubes (MWCNT) in poly-vinylidene (PVDF) matrix during mechanical rolling influence the texture, polymorphism and electromagnetic shielding properties. We demonstrate the flow induced orientation of MWCNT, polymorphism in PVDF and composites shielding performance by TEM, crystallographic texture and shielding effectiveness measurements, respectively. Further, mechanical and thermal properties of as pressed and mechanically rolled samples were investigated by DMA and DSC. TEM analysis revealed that MWCNT form small aggregate, however were aligned along the rolling direction. This observation is in sharp contrast to the random distribution for as pressed samples. Quantitatively, a strong texture was observed for rolled samples as compared to as pressed samples. Absorption of EM waves is the major shielding mechanism which is mechanistically discussed here through associated dielectric loss parameters. Interactions, alignment of MWCNTs, and polymorphism influence the shielding efficiency in these composites. In addition, stacking of such nanocomposite layers further enhances the overall shielding efficiency by absorption (up to 72%) due to the polarization, multiple internal reflections and interlayer charge storing capacity. A Bluetooth module was employed to successfully demonstrate the efficacy of this approach in supressing unwanted EM interference. This study comprehensively guides researchers as to how processing or flow-induced changes alter the distribution of MWCNTs in polymer composites and how this influences the overall shielding behaviour.

Synergistic enhanced dielectric properties of PVDF nanocomposites containing γ-oxo-pyrenebutyric acid functionalized graphene and BaTiO3 nanofillers

Abstract To investigate the synergies of graphene and BaTiO3 on the morphology and dielectric behavior of poly(vinylidene fluoride) (PVDF), γ-oxo-pyrenebutyric acid-modified graphene (GPA) and BaTiO 3 were incorporated into PVDF matrix by using solution-cast and hot-pressing method. π-π interaction between graphene (Gra) and γ-oxo-pyrenebutyric acid (PA), and the hydrogen bonding effect between hydroxy groups on BaTiO3 and PVDF can improve the dispersity of Gra and BaTiO3 in PVDF matrix. The addition of BaTiO3 improved further the dielectric permittivity that originates from high dielectric BaTiO3 , and remarkable interfacial polarization effect between PVDF and fillers, and the non-conducting organic groups of PA can support the low loss and conductivity in PVDF/GPA/BT composites that shows potential application as high dielectric material over a broad temperature range.

Controllable Synthesis of One‐Dimensional MoO3/MoS2 Hybrid Composites with their Enhanced Efficient Electromagnetic Wave Absorption Properties

One-dimensional MoO3 /MoS2 hybrid composites were synthesized by hydrothermal synthesis, and flexible MoO3 /MoS2 /PVDF nanocomposites could be prepared in a controlled fashion by combining the MoO3 /MoS2 composites with polyvinylidene fluoride (PVDF) matrix. The MoO3 /MoS2 /PVDF hybrids with a low filler content (20 wt %) exhibited distinct microwave absorption properties in the range of 2-18 GHz. The minimum reflection loss can reach -38.5 dB at 8.7 GHz, and the reflection loss was less than -10 dB in the frequency range from 3.03-11.02 GHz with an absorber thickness of 2.0-5.0 mm. The MoO3 /MoS2 /PVDF nanocomposites exhibited better absorption properties than pure MoO3 and MoS2 . The possible microwave absorption mechanism was also discussed in detail.