Phase Of PVDF Research Articles

Machine Learning-Enabled Nanoscale Phase Prediction in Engineered Poly(Vinylidene Fluoride).

Engineered poly(vinylidene fluoride) (PVDF) with its diverse crystalline phases plays a crucial role in determining the performance of devices in piezo-, pyro-, ferro- and tribo-electric applications, indicating the importance of distinct phase-detection in defining the structure-property relation. However, traditional characterization techniques struggle to effectively distinguish these phases, thereby failing to offer complete information. In this study, multimodal data-driven techniques have been employed for distinguishing different phases with a machine learning (ML) approach. This developed multimode model has been trained from empirical to theoretical data and demonstrates a classification accuracy of >94%, 15% more noise resilience, and 11% more accuracy from unimodality. Thus, from conception to validation, an alternative approach is provided to autonomously distinguish the different PVDF phases and eschew repetitive experiments that saved resources, thus accelerating the process of materials selection in various applications.

Fabrication of Electrospun Porous TiO2 Dielectric Film in a Ti–TiO2–Si Heterostructure for Metal–Insulator–Semiconductor Capacitors

The development of metal–insulator–semiconductor (MIS) capacitors requires device miniaturization and excellent electrical properties. Traditional SiO2 gate dielectrics have reached their physical limits. In this context, high-k materials such as TiO2 are emerging as promising alternatives to SiO2. However, the deposition of dielectric layers in MIS capacitors typically requires high-vacuum equipment and challenging processing conditions. Therefore, in this study, we present a new method to effectively fabricate a poly(vinylidene fluoride) (PVDF)-based TiO2 dielectric layer via electrospinning. Nano-microscale layers were formed via electrospinning by applying a high voltage to a polymer solution, and electrical properties were analyzed as a function of the TiO2 crystalline phase and residual amount of PVDF at different annealing temperatures. Improved electrical properties were observed with increasing TiO2 anatase content, and the residual amount of PVDF decreased with increasing annealing temperature. The sample annealed at 600 °C showed a lower leakage current than those annealed at 300 and 450 °C, with a leakage current density of 7.5 × 10−13 A/cm2 when Vg = 0 V. Thus, electrospinning-based coating is a cost-effective method to fabricate dielectric thin films. Further studies will show that it is flexible and dielectric tunable, thus contributing to improve the performance of next-generation electronic devices.

Electrical Response of Different Crystalline Microregions in Poly(vinylidene fluoride).

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.

Synergistically enhanced PVDF-based nanofiber membranes randomly embedded with ZnWO4@PDA nanorods for self-powered sensors with multi-mode free switching

In spite of the high level of attention paid to multifunctional sensors, the flexible and multifunctionality are still intractable challenges to be tackled. Herein, we design a flexible, hydrophobic and stable multifunctional sensing material by electrostatic spinning of PVDF/ZnWO4@PDA (PZP). The incorporation of ZnWO4@PDA into PVDF nanofibers can act as an effective nucleating agent and photosensitizer, which increases the polar crystalline phase and photovoltaic properties of PVDF. With the synergy of PVDF and ZnWO4@PDA, PZP based piezoelectric sensors offer significantly superior electrical output (28.4 V, 600 nA) and high sensitivity (1.04 V/kPa). Moreover, it is particularly surprising that photoelectric sensor based on PZP textiles has excellent optical properties, as confirmed by the response/recovery time (0.6 s/0.66 s) of simulated sunlight detection. Piezoelectric photoelectric effect exists in PZP textiles, as evidenced by the significant increase in the strain output current of photoelectric sensor when irradiated with sunlight. Furthermore, based on the coupling of piezoelectric effect and triboelectric effect of PZP composite, the contact out nano-triboelectric generator has enhanced the electrical output and electromechanical conversion efficiency. Therefore, this work has successfully prepared multifunctional sensing materials that integrate pressure sensing, audio recognition, underwater communication, optoelectronic detection and triboelectric energy collection, paving a new way for the flexible multifunctional sensors.

Enhancing self-induced polarization of PVDF-based triboelectric film by P-doped g-C3N4 for ultrasensitive triboelectric pressure sensors

Progress in wearable energy devices has reached the point of popularity over a few decades, as reflected by the rise of numerous sensors and storage devices driven by the urgent need for Internet of Things (IoT) applications. Triboelectric sensor (TES), on the basis of triboelectric nanogenerators (TENGs), exhibits high sensitivity and stability for pressure detection. Maximizing the sensitivity of the TES hinges upon the triboelectric layer selection capable of harnessing triboelectrification and electrostatic induction. Among them, PVDF has gained attention owing to its exceptional flexibility and tribo-negativity. However, the multiphase of pristine PVDF poses challenges, limiting its potential for TES with higher sensitivity. Tackling this issue, herein, we introduced phosphorus-doped graphitic carbon nitride (PCN) into the PVDF films to achieve self-induced polarization to enhance the sensitivity of the triboelectric pressure sensor. Through a controlled annealing temperature, phosphorus atoms are incorporated into the g-C3N4 (CN) matrix, enhancing the electronegativity of PVDF/PCN composite film while inducing a polarized β crystal phase in PVDF, thereby enabling greater attraction of positive charges. Consequently, the triboelectric output with PVDF/PCN composite film exhibited a significant improvement compared to the pristine PVDF film, achieving over a 100 V increment and the ability to power more than 100 LEDs. Furthermore, for the pressure-sensing applications, the TES with flexible PVDF/PCN triboelectric film exhibits a pressure sensitivity of 1.48 V/kPa, which shows a threefold increase in sensitivity compared to the pristine PVDF film (0.51 V/kPa), suggesting their great potential in self-powered wearable pressure sensors.

Dielectric, thermal and optical properties of PVDF-based (LaFeO3)0.5 (BaTiO3)0.5 perovskite composite films for advanced technological applications

(1-x)PVDF/(x)LFO-BTO composite films with weight percentages (x = 0, 0.05, 0.1 and 0.15) were prepared by solution casting method. Phase identification was carried out using the X-ray diffraction (XRD) technique revealing different phases (α, β & γ) of PVDF. FTIR results confirmed the presence of different vibrational modes and phases including PVDF phases. AFM and SEM were used to investigate the surface & morphological analysis, the results showed that the surface roughness increased with the concentration of LFO-BTO into PVDF films. From optical absorption spectra, the direct band gap and indirect band gap energies of the PVDF/LFO-BTO were evaluated by incorporating Tauc's relation. The composites experienced a reduction in band gap upon the addition of 0 - 15 wt% of LFO-BTO with an increasing trend in Urbach's energy. The dielectric investigations revealed elevated dielectric constant values across all composites at lower frequency ranges, attributed to interfacial polarization. Specifically, the dielectric constant of 15 % wt of LFO-BTO was found to be much higher (6 times more than the pristine PVDF). Additionally, the dielectric loss was suppressed with increasing filler concentration within the frequency range of 1 KHz to 1 MHz. Impedance spectroscopy analysis depicted a distinctive semi-circular pattern that was linked to the underlying conduction mechanism. The behaviour of ac-conductivity revealed the conduction process following the Nyquist plot. DTA-TGA analysis showed a notable improvement in thermal stability with increasing concentration in the PVDF matrix.

Synergistic Interaction of Ionic Liquid Grafted Poly(vinylidene Fluoride) and Carbon Nanotubes to Construct Water Treatment Membranes with Multiple Separation Properties.

In this study, the dual strategy of 1-butyl-3-vinylimidazolium bromide ionic liquid (IL) grafting and carbon nanotubes (CNTs) nanocomposition was applied to modify poly(vinylidene fluoride) (PVDF)-based membranes. The highly hydrophilic/oleophobic and fouling-resistant PVDF-g-IL/CNTs membranes with excellent separation efficiency were obtained by the nonsolvent-induced phase separation method with ethanol-water mixed solution as the coagulation bath. The grafted IL not only generated hydrophilic groups on PVDF chains but also acted together with the CNTs to induce the formation of hydrophilic β-crystalline phase of PVDF, which significantly improved the hydrophilicity and pore structure of the modified PVDF membranes. As a result, the pure water flux of the optimal membrane increased up to 294.2 L m-2 h-1, which was 5.2 times greater than that of the pure PVDF membrane. Simultaneously, the electrostatic interaction of the positive IL and the integration of CNTs enhanced adsorption sites of the membranes, producing exceptional retention and adsorption of dye wastewater and oil-water emulsion. This study presents a straightforward and efficient approach for fabricating PVDF separation membranes, which have potential applications in the purification of various polluted wastewater.

Structural, morphological, and dielectric properties of poly(vinylidene fluoride)/(Bi0.5Ba0.25Sr0.25) (La0.5Ti0.5) O3 composites

AbstractFerroelectric flexible polymer composite films of poly(vinylidene fluoride) (PVDF) with different weight percentages (10.0%, 20.0%, 30.0%, 40.0%, and 50.0%) of (Bi0.5Ba0.25Sr0.25) (La0.5Ti0.5) O3 were synthesized by solvent casting method. Analysis using the x‐ray diffractometer and Fourier transform infrared spectroscopy tools revealed the presence of the different phases (α, β) of PVDF. Scanning electron microscope morphology illustrates the homogenous dispersion of ceramics particles in the matrix. The differential scanning calorimetry curve (under 25–400°C) gives the value of melting temperature (Tm=169.98°C) and percentage crystallinity is about 29.45% for 50 wt.% composite. The findings demonstrated that the composite has good thermal stability up to 169.98°C. Dielectric analysis shows ferroelectric and dielectric behavior and also distinguishes α and β phases of PVDF. It was found that the composite film containing 50 wt.% (Bi0.5Ba0.25Sr0.25) (La0.5Ti0.5) O3 had a dielectric constant (εr) of 38 (at 100 Hz) and dielectric loss of 0.059, which are the maximum among the samples. The relative permittivity rises with an increase in filler content due to electrostatics and interfacial polarization between PVDF (CH2CF2 dipole) and ceramic. The real and imaginary part of impedance spectroscopy with frequency (Cole–Cole plots) for composite (10.0–50.0 wt.%) at 25°C are also investigated. The current study provides a fresh perspective on the fact that PVDF‐(Bi0.5Ba0.25Sr0.25) (La0.5Ti0.5) O3 composite system has improved thermal stability and dielectric characteristics.

Enhanced Hydrogen Evolution in Porous and Hybrid g‐C3N4/Pt‐PVDF Electrospun Membranes via Piezoelectricity from Water Flow Energy

AbstractInspired from seaweed swayed by waves, the enhanced hydrogen evolution is realized in porous and hybrid g‐C3N4/Pt‐PVDF electrospun membranes via piezoelectricity from water flow energy. The membranes are fabricated by dispersing g‐C3N4/Pt into the mixed solution of PVDF and PEO, followed by electrospinning and selective removal of PEO. By changing the PEO amount, the pore size in nanofibers is adjusted. Due to the hydrogen bonding between g‐C3N4/Pt and PVDF, the β phase of PVDF is increased, beneficial for the piezoelectricity performance. When the electrospun membranes are exposed to water flow, an additional potential field is triggered due to the deformation of PVDF. It not only eases the photogeneration of charge carriers from g‐C3N4/Pt but also hinders their recombination. The prolonged lifetime significantly improves the photocatalytic water splitting of g‐C3N4/Pt under visible light. The hydrogen evolution in the electrospun membranes (PVDF to PEO = 4:1) is profoundly improved to 9 278 µmol h−1 g−1, almost doubled to the pure g‐C3N4/Pt nanosheets (5 220 µmol h−1 g−1). Therefore, the seaweed‐inspired electrospun membrane is a promising strategy for the efficiently photocatalytic water splitting via g‐C3N4 in an aqueous environment, such as a natural sea and lake, by the piezoelectricity gained from the water flow energy.

Magnetostriction enhanced self-powered nanofiber sheet as cardiac patch with magnetoelectric synergistic effect on actuating Na+ k+-ATPase

Cardiac tissue engineering has great promise in the treatment of heart disease. Aiming to develop the novel magnetoelectric cardiac patch for improving the non-conduction of injured myocardium after myocardial infarction, the self-powered nanofiber sheet was electro-spun by doping magnetostrictive CoFe2O4 in piezoelectric Poly (vinylidene fluoride) (PVDF). The piezoelectric ratios increased several folds with the doping of CoFe2O4 due to the increased β phase and crystallinity of CoFe2O4-PVDF confirmed by experimental data. Molecular Dynamics and Finite Element Simulation demonstrated that non-β phase transformed to β phase of PVDF with doping CoFe2O4 and the deformation of CoFe2O4 enhanced the piezoelectric effect of PVDF, respectively. The proliferation and spread area of Doxorubicin-induced oxidative stress injured cardiomyocytes, H9c2 cells, were significantly improved under magnetoelectric cue compared with those without magnetoelectric cue when co-cultured with CoFe2O4-PVDF. Importantly, a new mechanism pathway of magnetoelectric cue on cardiomyocytes has been found, including up-regulating of steroid hormone biosynthesis, enhancing of sodium–potassium enzyme, and increasing of intracellular Ca2+, which would trigger the cardiomyocyte contraction to overcome the non-conduction of injured cardiomyocytes by RNA-seq transcriptome sequencing, Polymerase Chain Reaction and downstream expression analysis. Hence, this CoFe2O4-PVDF composite nanofiber sheet would be potentially used as the magnetoelectric cardiac patch to treat injured myocardium after myocardial infarction clinical.

Unravelling the role of poly(methyl methacrylate) (PMMA) molecular weight in poly(vinylidene fluoride) (PVDF)/PMMA/expanded graphite (ExGr) blend nanocomposites: Insights into morphology, thermal behavior, electrical conductivity, and wetting property

Poly(vinylidene fluoride) (PVDF) based conducting polymer composites with carbon nanomaterials can be used for mechanical energy harvesting through piezoelectric or triboelectric effect. This study aims to investigate the influence of PMMA molecular weight on the electrical, thermal, and wetting properties of PVDF/40 wt.% PMMA blend nanocomposites reinforced with expanded graphite (ExGr). The blend nanocomposites with 40 wt.% PMMA have been prepared by solution blending method by using two different molecular weights of PMMA whose melt flow indices are 2 g/10 min and 2.3 g/10 min. The coexistence of the electroactive gamma and non-polar alpha phases of PVDF in the blend nanocomposites has been confirmed by X-ray diffraction, Fourier transform infrared spectroscopy and differential scanning calorimetry analyses. While overall crystallinity (%) of low molecular weight PMMA employed blend nanocomposites is lower than that of high molecular weight PMMA blended nanocomposites, the electroactive gamma phase has been found to increase in the former blend nanocomposites. The dispersion of graphite nanosheets has been observed to be better in high molecular weight PMMA employed blend nanocomposites which results in higher electrical conductivity. Impedance analysis of PVDF-40 wt.% PMMA-2 wt.% ExGr blend nanocomposite with high molecular weight PMMA results in enhanced interjunction capacitance (74.5 pF) in comparison to low molecular weight PMMA mixed blend nanocomposites (68 pF). Water contact angle (WCA) increases with molecular weight of PMMA and ExGr loading level. Thermogravimetric analysis has shown that the char content (above 500°C) is slightly higher for the blend with low molecular weight PMMA than with high molecular weight PMMA.

Synergistic piezocatalytic activity of hybrid BZT/Graphene/PVDF composites

In this study, piezocatalyst composites were synthesized using hybrid films of Ba(Zr,Ti)O3/Polyvinylidene fluoride (BZT/PVDF) with graphene nanoplatelets (GNP) for the Rhodamine B (RhB) discoloration. X-ray diffraction and Raman spectroscopy analyses confirmed composite formation without altering short/long-range structures, stabilizing the β phase of PVDF. Scanning electron microscopy revealed crucial morphological changes influencing the piezocatalytic response of the films. RhB discoloration tests underscored the efficacy of BZT/GNP/PVDF composites due to enhanced system polarization provided by GNP. This work provides insights into the delicate balance of components for flexible, heavy metal-free piezocatalyst composites, advancing their design and applications.

PVDF/PI/BT nanocomposites with excellent charge/discharge efficiency obtained by inserting linear polymer to adjust the ferroelectricity

The problem of low charge/discharge efficiency of ceramic/polymer composites is still one of the hot topics in current research on dielectric materials. Here, we demonstrate that the ferroelectric property of ceramic/PVDF-based composites can be modulated by the introduction of linear polymer PI and the use of a spin-coating process. PI inhibits some polarization and partial dipole orientation by interacting with the molecular chains of the amorphous phase of PVDF and BT nanoparticles. As a result, the decrease in crystallinity and loss led to improved dielectric properties and charge/discharge efficiency. The findings demonstrate that the microstructure of PVDF-PI/BT nanocomposite is uniform and dense, with outstanding dielectric characteristics and high charge/discharge efficiency. The permittivities were stabilized in the range of 12.87–17.86 at 100 Hz, and the dielectric losses were all less than 0.27. Compared with the previously reported binary ceramic/polymer composites, the PVDF-PI/BT nanocomposites possessed a high charge/discharge efficiency with a small variation (63%-84%). This work offers an easy and efficient scheme to obtain nanocomposites with outstanding dielectric characteristics and charge/discharge efficiency. It may be a potential candidate for flexible dielectric substrates for advanced flexible capacitive energy storage devices.

Enhanced dielectric properties of PVDF polymer nanocomposites: A study on gold−decorated, surface−modified multiwalled carbon nanotubes

The integration of surface-modified multiwalled carbon nanotubes (fMWCNTs) into polymer nanocomposites has been extensively studied for their potential to enhance dielectric properties. This study, however, pioneers the use of a novel hybrid filler comprising fMWCNTs coated with metal nanoparticles, specifically aimed at augmenting the dielectric performance of polymers. In our research, poly(vinylidene fluoride) (PVDF) nanocomposite films were synthesized using fMWCNTs with a diameter of ∼6–9 nm and a length of 5 μm, adorned with gold nanoparticles (nAu) of ∼5.4 ± 0.9 nm via an adapted Turkevich method. Comprehensive analyses were conducted on nAu−fMWCNTs hybrid powder and their nanocomposites in PVDF with varying filler concentrations, confirming the formation of nAu−fMWCNTs with a weight ratio of 1.1 : 98.9. Three−phase percolative nanocomposites were produced by dispersing the hybrid filler in N,N−dimethylformamide, facilitated by interactions between the negative charge of nAu−fMWCNTs (zeta potential of ∼ −40.43 ± 0.46 mV) and polar phases of PVDF. This was verified through zeta potential and Fourier−transform infrared spectroscopy analyses. The dielectric permittivity (ε′) of the nanocomposites significantly increased from 17.8 to 524.8 (at 1 kHz) with filler loadings from 0.005 to 0.01 vol%, while the dielectric loss tangent (tanδ) showed a minor increase from 0.05 to 1.18. These enhancements are attributed to the elevated permittivity of nAu−fMWCNTs hybrid powder, PVDF's transition to the β−phase, and interfacial polarization effects. The restrained growth of nAu on fMWCNTs and the inhibition of conductive pathways in the polymer matrix contributed to the low tanδ values.

Enhanced nanogenerator by embedding lead-free double perovskite Cs2AgBiBr6 in polymer matrix for hybrid energy harvesting

CABB addition with high dielectric constant and low dielectric loss facilitates PVDF phase transition and device outputs enhancement.

Dielectric Filler-Induced Hybrid Interphase Enabling Robust Solid-State Li Metal Batteries at High Areal Capacity.

The fillers in composite solid-state electrolyte are mainly responsible for the enhancement of the conduction of Li ions but barely regulate the formation of solid electrolyte interphase (SEI). Herein, a unique filler of dielectric NaNbO3 for the poly(vinylidene fluoride) (PVDF)-based polymer electrolyte, which is subjected to the exchange of Li+ and Na+ during cycling, is reported and the substituted Na+ is engaged in the construction of a fluorinated Li/Na hybrid SEI with high Young's modulus, facilitating the fast transport of Li+ at the interface at a high areal capacity and suppressing the Li dendrite growth. The dielectric NaNbO3 also induces the generation of high-dielectric β phase of PVDF to promote the dissociation of Li salt. The Li/Li symmetrical cell exhibits a long-term dendrite-free cycling over 600h at a high areal capacity of 3mA h cm-2. The LiNi0.8Mn0.1Co0.1O2/Li solid-state cells with NaNbO3 stably cycle 2200 times at 2 C and that paired with high-loading cathode (10mg cm-2) can stably cycle for 150 times and exhibit excellent performances at -20 °C. This work provides a novel design principle of fillers undertaking interfacial engineering in composite solid-state electrolytes for developing the safe and stable solid-state lithium metal battery.

Investigation of the effects of different zwitterions in fabricating smart PVDF/graphene pervaporation membranes

Although membrane separation processes including pervaporation have demonstrated their as an efficiency in chemical waste treatment and resource recovery, the increasingly complex wastes generated by different industrial sectors make it almost impossible for a single membrane that has a fixed set of properties to handler these kinds of contaminants. For this reason, stimuli responsive membranes that have tunable and switchable properties are necessary to be developed. In this research, we explore the impacts of zwitterion compounds as additives to previously formulated PVDF-graphene membrane where graphene was used to facilitate β-phase induction of PVDF, enhancing its piezoelectric properties. The incorporation of zwitterions intended to even promote the β -crystal phase of PVDF, which is also facilitated by an optimized quantity of graphene. The quantified β phase of pristine PVDF- (68.7 %) was observed to increase to 79.4 %-86.32 %, when different zwitterions are added. Moreover, output voltages from piezoelectric testing of membranes under various weights generated a voltage signal up to 1.69 V for the membrane with the 3-(1-Pyridinio-1-propanesulfonate) zwitterion, named as PGzc membrane. Upon employing these membranes to dehydrate isopropanol by pervaporation, it was found out that PG shows a permeation flux (Pf) of 95.49 ± 9.18 g/m2h and 77 % water concentration in permeate (Wcp) while the PGzc.membrane displayed a Pf and Wcp of 988.84 ± 51 g/m2h and 30 %, respectively. But upon application of an external voltage, it was found out that PGzc's Wcp rises from 30 % to 83 % with increasing voltage and while the Pf gradually falls from 988.84 ± 51 g/m2h to 432.51 ± 19 g/m2h. These findings indicate that the addition of an appropriate zwitterion could significantly influence the piezoelectric properties of PVDF-graphene membranes, enhancing their tuning capability under electrical stimulation. This development is important for separation processes and technologies aimed at creating a sustainable society.

Synergistic enhancement of thermal and dielectric properties in PVDF films with Au-BaTiO3 hybrid nanoparticles

In our investigation of poly(vinylidene fluoride) (PVDF) films embedded with Au-BaTiO3 (AuBT) nanoparticles, we noted a synergistic improvement in both thermal stability and dielectric properties. PVDF films with varying concentrations of AuBT were expertly fabricated. Remarkably, the films retained their flexibility even at a high volume fraction of filler (f AuBT = 0.5). The predominant phases of PVDF (α, β, and γ) were observed. An increase in f AuBT resulted in a modest decrease in the melting temperature, while simultaneously causing a significant 40% increase in thermal conductivity compared to pure PVDF. The dielectric permittivity reached ∼160 at 1 kHz, while maintaining a loss tangent of ∼0.05. These improvements were attributed to discrete Au growth on BT particles, hindering conduction in PVDF. The rise in dielectric response resulted from interfacial polarization and inherent high dielectric permittivity of BT.

Process controlled microstructure of polyvinylidene fluoride/functionalized single walled carbon nanotube composites

AbstractPolyvinylidene fluoride (PVDF)‐functionalized single walled carbon nanotube (FSWCNT) film composites were prepared by two different process conditions—air drying and vacuum drying. Though reports on –PVDF‐FSWCNT composites are available, we provide a new outlook here, which is based on optimized functionalization and novel processing conditions. The microstructural and phase changes occurring in PVDF having nanotubes functionalized for different extent of time were investigated and confirmed that those functionalized for 4 h (FSWCNAT‐4) create polar γ phase in PVDF with improved mechanical and electrical properties. X‐ray photoelectron spectroscopy studies showed that PVDF/FSWCNT‐4 composites have the maximum percentage of functional groups. It is also found that PVDF/FSWCNT‐4 composite films prepared through air drying were rough and had a cloudy appearance suitable for applications demanding open porous structures, whereas those prepared through vacuum drying process were smooth and homogeneous with high optical transparency, suitable for microelectronic applications. Thus, by suitably controlling the processing conditions and by using optimally functionalized nanotubes, PVDF films with multifunctional properties could be achieved. In order to extract the full capabilities of PVDF/SWCNT films, functionalization of the nanotube together with processing conditions plays a significant role.

Piezoelectric properties of noncovalently functionalized 2D nanomaterials incorporated poly(vinylidene fluoride) nanocomposites

AbstractWe report here for the first time the role of noncovalently functionalized 2D nanomaterials on the ferroelectric and piezoelectric behavior of poly(vinylidene fluoride) (PVDF) nanocomposites. Graphene oxide (GO), expanded graphite (EG) and hexagonal boron nitride (h‐BN) were noncovalently modified via Li‐salt of 6‐amino hexanoic acid (Li‐AHA), denoted as m‐GO, m‐EG and m‐BN, in order to de‐agglomerate and de‐stack them, which were subsequently incorporated into the PVDF matrix via solution mixing, followed by compression molding. Simultaneously, PVDF nanocomposites with unmodified 0.08 wt% of 2D nanomaterials were also prepared using the same methodology. PVDF/m‐BN nanocomposite showed a higher extent of polar phase (~36%) associated with PVDF phase as compared to PVDF/m‐GO and PVDF/m‐EG nanocomposites. Further, the highest permittivity (~58 at 10−1 Hz) was achieved in PVDF/m‐BN nanocomposite, which was also reflected in higher remnant polarization (~61 nC/cm2) and a significantly higher d33 value (~53 pm/V). Moreover, a higher output peak to peak voltage (~13 V) was obtained for the sensor device fabricated from PVDF/m‐BN nanocomposite. Thus, the role of Li‐AHA‐modified 2D nanomaterials in improving the morphology, dielectric, ferroelectric, and piezoelectric characteristics of the PVDF nanocomposites was clearly established.