The present work deals with the preparation, characterization, and application of self-poled nanofibers using piezoelectric polymer poly­(vinylidene fluoride-trifluoroethylene), zinc oxide, and exfoliated graphene oxide by electrospinning process. The characterization of nanofiber is carried by different techniques such as field emission scanning electron microscopy, Fourier transform Infrared spectroscopy, X-ray diffraction techniques, and dynamic contact mode electrostatic force microscopy. The nanofiber based piezoelectric nanoenergy generator devices are fabricated for analyzing the energy generating efficiency. Piezoelectric hybrid nanofibers are exhibiting better energy generating efficiency and identified as potential material for energy harvesting applications.

The effect of barium titanate (BaTiO3) nanoparticles (particle size <100nm) on the ferroelectric properties of poly (vinylidenefluoride-trifluoroethylene) P(VDF-TrFE) copolymer has been studied. Different concentrations of nanoparticles were added to P(VDF-TrFE) using probe sonication, and uniform thin films were made. Polarisation - Electric field (P-E) hysteresis analysis shows an increase in remnant polarization (Pr) and decrease in coercive voltage (Vc). Piezo-response force microscopy analysis shows the switching capability of the polymer composite. The topography and surface roughness was studied using atomic force microscopy. It has been observed that this nanocomposite can be used for the fabrication of non-volatile ferroelectric memory devices

Barium titanate nanoparticles with an average size of <100 nm were added to poly(vinylidene fluoride‐trifluoroethylene) copolymer in varying concentrations (0.2, 0.4, 0.6, and 0.8 wt%) in liquid phase under bath sonication and annealed at 120°C for 2 h. The Fourier transform infrared spectroscopy, X‐ray diffraction, Raman spectroscopy, and Differential scanning calorimetry studies reveals an increase in the β‐phase content of the nanocomposite, which is a promising inference for the increased ferroelectric property of the material. Scanning electron microscopy and Atomic force microscopy was used to study the surface topography of the spin coated thin films. Polarization–electric field studies clearly indicating the enhanced ferroelectric nature of optimized concentration with highest remnant polarization. All these results nominate this polymer nanocomposite as a promising material for ferroelectric applications like nonvolatile memory devices. POLYM. COMPOS., 38:1655–1661, 2017. © 2015 Society of Plastics Engineers

We report the preparation, thermal and micro/nanomechanical behavior of poly (vinylidine diflouride) (PVDF)/multiwalled carbon nanotube (MWCNT) nanocomposites. It has been found that the addition of MWCNT considerably enhances the β-phase formation, thermal and mechanical properties of PVDF. Atomic force microscope (AFM) studies have been performed on the composites under stress conditions to measure the mechanical properties. The nanoscale mechanical properties of the composites like Young's modulus and hardness of the nanocomposites were investigated by nanoindentation technique. Morphological studies of the nanocomposites were also studied, observations show a uniform distribution of MWCNT in the matrix and interfacial adhesion between PVDF and MWCNT was achieved, which was responsible for enhancement in the hardness and Young's modulus. Differential scanning calorimetry (DSC) studies indicate that the melting temperature of the composites have been slightly increased while the heat of fusion markedly decreased with increasing MWCNT content.

No abstract

The manuscript introduces the use of non-electrically polled spin-coated thin polyvinylidene fluoride (PVDF) films as the active layers in a contact electrification-based nanoenergy harvester. The four-layered device utilizes both piezo and triboelectric effect coupled with electrostatic induction. The elucidation of potential generation during contact between crystalline phases ( α and β) of PVDF layer material is investigated in the manuscript. Fourier transform infrared–attenuated total reflectance spectroscopy is carried out to illustrate the α- and β-phases in PVDF pellet, prepared film as well as the film after contact. Dynamic contact mode electrostatic force microscopy (DC-EFM) along with atomic force microscopy is used for the evaluation of reverse piezoelectric, local ferroelectric, triboelectric voltage and adhesive energy of the PVDF films before–after contact process. Quantum chemical calculation is performed using density functional theory to explain possible electron transitions in the active layers between the cylindrically symmetric α-phase and electrical double layer charges in the β-phase of PVDF. The interface study of the film is also carried out both experimentally using DC-EFM and through quantum chemical calculations. The fabricated device with the hybrid piezo-tribo layer promises to be a simple and low-cost energy source for the next-generation self-powered electronic devices. The device can also be used as knock sensor in engines as well as a capacitor.

The ferroelectric field effect transistor (FeFET) using Poly (vinylidene fluoridetrifluoroethylene)/Barium titanate [P(VDF-TrFE)/BaTiO 3 ] polymer nanocomposite as dielectric layer, has been fabricated and characterized. P(VDF-TrFE)/BaTiO 3 nanocomposite of 300 nm thin film over 10 nm SiO 2 was used in the optimized fabrication process sequence of FeFET. The addition of BaTiO 3 nanoparticle to the P(VDF-TrFE) copolymer has enhanced the ferroelectric property with an observed 2 V difference in memory window. The effect of temperature and frequency on these memory window characteristics were observed to optimized the stack thickness for an ideal FeCAP (ferroelectric capacitor).Drain current-drain voltage (I D -V D ) characteristics of P(VDF-TrFE)/BaTiO 3 FeFET shows significant variation in I D with pinch of voltage around 1 V for wide range of gate voltage (V G ). I ON /I OFF ratio of FeFET using P(VDF-TrFE)/BaTiO 3 was found to be 35, which was higher than the ratio of FeFET fabricated using P(VDF-TrFE) copolymer (4.4). I D -V G characteristics of both the FETs clearly indicate a lower threshold voltage (0.83 V) for P(VDF-TrFE)/BaTiO 3 FET, which is almost three times lesser than threshold voltage of a P(VDF-TrFE) FET (2.5 V).

This work aims at the manipulation of nanoscopic voltage produced through uniform and non-uniform rubbing in neat unpolarised polymer polyvinylidene fluoride. A metal-insulator configuration is considered for the analysis. The decay of surface potential in such a configuration is also addressed in this work. The polarity of the voltage observed on the film depends on the work function of the metal electrode in contact as well as the electronegativity of polymeric material under study. Scanning probe microscopic techniques such as dynamic contact mode electrostatic force microscopy, scanning tunnelling microscopy are used for the investigation of specific electrostatic potential variation on polymer films. Effect of contact electrification leads to nanoscopic domains of voltage generation on the surface of the tribolayers. Electrostatic potential developed on the surface of unrubbed polymer film using modulated tip is in the range of 20-40 mV. The range of voltage generated increased from 20 to 125 mV in the case of rubbed polymer films. Charge retention is discussed through obtaining surface potential decay trend at various intervals. This also plays an important role in the generation of the voltage as well as the current. The above scenario has been demonstrated in both rubbed and unrubbed scenarios. Charge decay is observed to be gradually decreasing from 40 to 29.5 mV in unrubbed surface and 125 to 14 mV in rubbed surface for various time intervals. The obtained results suggest insignificance of triboelectric series on contact electrification between similar tribolayers.