Preparation and characterization of a PAN nanofibre containing Ag nanoparticles via electrospinning

A polyacrylonitrile (PAN) nanofiber containing Ag nanoparticles was prepared by an electrospinning technology. To prevent the nanoparticles from coagulating in polymer solutions, an approach of in-situ preparing nanoparticles in PAN solution was used. Diameters of the nanoparticles and nanofiber as well as distribution of the former in the latter were characterized by Transmission electron microscopy. Crystal structure of the nanoparticles was given by X-ray diffraction. Absorption spectrum of the nanocomposites was measured by UV-Vis. Conductivity of the nanocomposites was compared with the pure PAN nanofiber.

Structure retention in cross-linked poly(ethylene glycol) diacrylate hydrogel templated from a hexagonal lyotropic liquid crystal by controlling the surface tension

Retaining hexagonal lyotropic liquid crystal (LLC) structures in polymers after surfactant removal and drying is particularly challenging, as the surface tension existing during the drying processes tends to change the morphology. In this study, cross-linked poly(ethylene glycol) diacrylate (PEGDA) hydrogels were prepared in LLC hexagonal phases formed from a dodecyltrimethylammonium bromide (DTAB)/water system. The retention of the hexagonal LLC structures was examined by controlling the surface tension. Polarized light microscopy, X-ray diffraction and small angle X-ray scattering results indicate that the hexagonal LLC structure was successfully formed before polymerization and well retained after polymerization and after surfactant removal when the surface tension forces remained neutral. Controlling the surface tension during the drying process can retain the nanostructures templated from lyotropic liquid crystals which will result in the formation of materials with desired nanostructures.

Study of radio frequency plasma treatment of PVDF film using Ar, O2 and Ar + O2 gases for improved polypyrrole adhesion

Improvement of the binding of polypyrrole with PVDF (polyvinylidene fluoride) thin film using low pressure plasma was studied. The effects of various plasma gases i.e., Ar, O2 and Ar + O2 gases on surface roughness, surface chemistry and hydrophilicity were noted. The topographical change of the PVDF film was observed by means of scanning electron microscopy and chemical changes by X-ray photoelectron spectroscopy, with adhesion of polypyrrole (PPy) by abrasion tests and sheet resistance measurements. Results showed that the increase in roughness and surface functionalization by oxygen functional groups contributed to improved adhesion and Ar + O2 plasma gave better adhesion.

Electrical Stimulation of Myoblast Proliferation and Differentiation on Aligned Nanostructured Conductive Polymer Platforms

In this study, nanostructured conductive platforms synthesized from aligned multiwalled carbon nanotubes and polypyrrole are investigated as myo-regenerative scaffolds. Myotube formation follows a linear path on the platforms coinciding with extent of nanotopography. In addition, electrical stimulation enhances myo-nuclear number and differentiation. These studies demonstrate that conductive polymer platforms can be used to influence muscle cell behaviour through nanostructure and electrical stimulation.

A self-supported, flexible, binder-free pseudo-supercapacitor electrode material with high capacitance and cycling stability from hollow, capsular polypyrrole fibers

Flexible energy devices with high performance and long-term stability are highly promising for applications in portable electronics, but remain challenging to develop. As an electrode material for pseudo-supercapacitors, conducting polymers typically show higher energy storage ability over carbon materials and larger conductivity than transition-metal oxides. However, conducting polymer-based supercapacitors often have poor cycling stability, attributable to the structural rupture caused by the large volume contrast between doping and de-doping states, which has been the main obstacle to their practical applications. Herein, we report a simple method to prepare a flexible, binder-free, self-supported polypyrrole (PPy) supercapacitor electrode with high cycling stability through using novel, hollow PPy nanofibers with porous capsular walls as a film-forming material. The unique fiber structure and capsular walls provide the PPy film with enough free-space to adapt to volume variation during doping/de-doping, leading to super-high cycling stability (capacitance retention > 90% after 11000 charge-discharge cycles at a high current density of 10 A g^-1) and high rate capability (capacitance retention ∼ 82.1% at a current density in the range of 0.25-10 A g^-1).

The reduction of oxygen on iron(II) oxide/poly(3,4-ethylenedioxythiophene) composite thin film electrodes

© 2014 Elsevier Ltd. All rights reserved. Conducting polymers (CPs) are currently being investigated for use in many applications owing to their abilities to catalyze a wide range of electrochemical reactions and act as an effective electrode support for various inorganic and organic electrocatalyst materials. Here, we have found that the deposition of poly(3,4-ethylenedioxythiophene) (PEDOT) through the use of an established base-inhibited chemical vapor-phase polymerization (VPP) procedure using an iron(III) tosylate oxidant results in the co-deposition of electrocatalytic iron(II) oxide species within the film. The presence of these species accounts for the 2-electron reduction of hydrogen peroxide that occurs on these electrodes during the series 4-electron oxygen reduction reaction. Furthermore, this realization leads to the possibility of fabricating thin film inorganic/CP composites of various compositions through careful choice of oxidant in a facile, one-step process. A combination of in situ Raman (487.77 nm laser) and in situ UV-Vis spectroscopy was used to probe the oxidation state of PEDOT in the thin film composite electrodes while reducing oxygen in alkaline conditions. These measurements show that the 2-electron electroreduction of hydrogen peroxide (or HO2 -) occurs only on the iron(II) oxide species in a reaction that is facilitated by an effective electron transfer from the delocalized electron orbitals of the PEDOT matrix. This approach could potentially be used in situ to monitor the electrocatalyst/electrode interface quality of conducting polymer-supported electrocatalysts.

A novel and facile approach to fabricate a conductive and biomimetic fibrous platform with sub-micron and micron features

The demands of multifunctional scaffolds have exceeded the passive biocompatible properties previously considered sufficient for tissue engineering. Herein, a novel and facile method used to fabricate a core-shell structure consisting of a conducting fiber core and an electrospun fiber shell is presented. This multifunctional structure simultaneously provides the high conductivity of conducting polymers as well as the enhanced interactions between cells and the sub-micron topographical environments provided by highly aligned cytocompatible electrospun fibers. Unlimited lengths of PEDOT:PSS-Chitosan-PLGA fibers loaded with an antibiotic drug, ciprofloxacin hydrochloride, were produced using this method. The fibers provide modulated drug release with excellent mechanical properties, electrochemical performance and cytocompatibility, which hold great promise for the application of conductive electrospun scaffolds in regenerative medicine.

Conducting polymer electrochemistry in ionic liquids

Applications of polymers like polypyrrole and polythiophene often require interaction with an electrolyte consisting of solvent and dissolved salt. Ionic Liquids (ILs) are pure saits, fluid at room temperature, that form charged electrolytes. Pure l-Bu-3-Me-Imidazolium PF₆ (BMI PF₆) a hydrophobic IL that has a wide potential window, was used to investigate the electrochemistry ofpolypyrrole. Enhanced electrochemic~l stability of polypyrrole was obtained on repetitive redox cycling with respect to the equivalent propylene carbonate electrolyte with tetrabutylammonium hexaflurophosphate (TBA PF₆) electrolyte.

Performance study of a wind-grid system in a semi- arid region and major integration issues

The phenomenal growth in economy experienced in developed countries throughout the 20th century has largely been driven by the availability of conventional energy sources for electricity generation. However, increased concern about fossil fuels and adverse effect of carbon dioxide emission in to atmosphere changed the conventional power system to a viable one by integrating renewable energy sources into the existing system. Among the Renewable Energy (RE) sources, wind energy is one of the fastest growing technologies in reducing the Green House Gas (GHG) emissions in to the atmosphere due to its continuous availability throughout a period. Hence, this paper discusses the performance of a wind-grid connected system in a semi-arid region by conducting a case study. Wilson promontory, one of the best locations for wind generation in Victoria is considered as a case study. Hybrid Optimization Model for Electric Renewable (HOMER) is used as a simulating tool for this analysis. This study also presents the influences of storage system in the proposed Hybrid Power System (HPS) allowing energy to be stored during higher generations or lower load demands. In addition this paper also discusses the major integration issues to facilitate the large scale wind energy into the grid for reliable power generation and distribution.