Nanowires Of Poly Research Articles

A Scalable Nanogenerator Based on Self‐Poled Piezoelectric Polymer Nanowires with High Energy Conversion Efficiency

Nanogenerators based on piezoelectric materials convert ever-present mechanical vibrations into electrical power for energetically autonomous wireless and electronic devices. Nanowires of piezoelectric polymers are particularly attractive for harvesting mechanical energy in this way, as they are flexible, lightweight and sensitive to small vibrations. Previous studies have focused exclusively on nanowires grown by electrospinning, but this involves complex equipment, and high voltages of $\approx$ 10 kV that electrically pole the nanowires and thus render them piezoelectric. Here we demonstrate that nanowires of poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) grown using a simple and cost-effective template-wetting technique, can be successfully exploited in nanogenerators without poling. A typical nanogenerator comprising $\approx$ 10$^{10}$ highly crystalline, self-poled, aligned nanowires spanning $\approx$ 2 cm$^2$ is shown to produce a peak output voltage of 3 V at 5.5 nA in response to low-level vibrations. The mechanical-to-electrical conversion efficiency of 11% exhibited by our template-grown nanowires is comparable with the best previously reported values. Our work therefore offers a scalable means of achieving high-performance nanogenerators for the next generation of self-powered electronics.

Agglomerated carbon nanotube-induced growth of piezoelectric 3D nanoarchitectures assembled from hollow 1D nanowires of poly (vinylidene fluoride) at high pressure

Abstract Carbon nanotubes (CNTs) intrinsically tend to bundle and/or aggregate, and various techniques were explored to improve the dispersibility of CNTs in polymer matrices during the preparation of a variety of CNT/polymer based composites. However, herein we report the entangling nature of CNTs can be utilized for the rapid formation of unique piezoelectric three dimensional (3D) nanoarchitectures of poly (vinylidene fluoride) (PVDF). The controllable growth of the 3D nanostructures, assembled from hollow one dimensional (1D) PVDF nanowires, was achieved by the high-pressure crystallization of a binary CNT/PVDF based composite, in which CNT agglomerations were not destroyed during the fabrication process. This was attributed to the cooperation effect of the agglomerated CNTs served as hard-template and the physical interactions of macromolecular chains at high pressure as self-assembly driving forces. The present study provides a facile and effective approach to construct functional 3D nanostructures in situ, and the hybrid structures, consisting of CNTs and piezoelectric PVDF nanowires, may permit niche applications in a self-powering nanosystem that harvests its operating energy from the environment.

Nanowires of 3-D cross-linked gold nanoparticle assemblies behave as thermosensors on silicon substrates

In this study, we used a novel fabrication process, involving electron beam lithography and oxygen plasma treatment, to generate line and dot patterns of (3-mercaptopropyl)trioxysilane units over a large area of the Si(100) surface for gold nanoparticle (AuNP) immobilization. We synthesized the AuNPs in a two-phase system for assembly onto the Si substrate through coordination to the thiol groups of the protecting organic shell patterns. The resulting bottom layer of AuNPs was then treated with 1,6-hexanedithiol to generate thiol groups on their surfaces, thereby allowing the bottom-up construction of multiple layers of three-dimensional cross-linked AuNP assemblies, so-called poly(AuNP), linked directly to the Si substrate. We fabricated nanowires of cross-linked three-layer poly(AuNP) over large areas, with resolutions ranging from 200 nm to 10 μm. The nanowires of the poly(AuNP) underwent dramatic changes in their electrical resistivities and morphologies when melting began at a temperature of 140°C. For example, the resistivity of the nanowires assembled from three layers of poly(AuNP) at a width of 1 μm increased rapidly from 8.99 × 10–4 to 9,471 Ω m upon increasing the temperature from room temperature to 140°C. Such microwires assembled from lines of poly(AuNP) might, therefore, be applicable as thermosensors on Si surfaces in devices miniaturized to the nanoscale.

Characteristics and photoluminescence of nanotubes and nanowires of poly (3-methylthiophene)

We synthesized nanotubes and nanowires of π-conjugated poly (3-methylthiophene) (P3MT) by using nanoporous anodic aluminum oxide (Al2O3) template through electrochemical polymerization method. From scanning electron microscope and transmission electron microscope photographs, we observed the formation of nanotubes with diameters of 100–200 nm and wall thicknesses of 5–10 nm. Relatively long nanotubes and nanowires of P3MT (about 40μm in length) were obtained. To discern the structural and optical properties of the systems, we measured ultraviolet and visible absorbance and Fourier transform-infrared spectroscopy. We observed that the doping level, the π-π* transition peak, and bipolaron peaks in P3MT nanotubes varied with synthetic temperature. The photoluminescence (PL) spectra of the P3MT nanotubes solution were observed at ∼490nm. For the P3MT nanotubes synthesized at lower temperatures, the PL peaks became sharper and the resistance decreased.

Effects of the Confined Synthesis on Conjugated Polymer Transport Properties

Previous studies on conjugated polymer nanotubules, prepared by the template method, established that improvements in the molecular and supermolecular structure are responsible for the increase in the room temperature conductivity when the diameter decreases. Our study clearly indicates that a more complex situation can result from the confined synthesis of conjugated polymers in nanopores of a template. Nanowires of poly(3,4-ethylenedioxythiophene), a polythiophene derivative, have been prepared by electrochemical synthesis in polycarbonate templates with diameters ranging between 35 and 200 nm. The electrical transport study (down to 1.5 K) shows that the smaller the nanowire diameter, the stronger the insulating behavior. The temperature dependence of the sample resistance ranges between two extremes, a nonthermally activated regime for the PEDOT film close to the metal−insulator transition and a 2D Mott-variable range hopping-like regime for 35-nm nanowires. It is partly related to the doping level, d...