Electrical Conductive Polymer Research Articles

A wireless photovoltaic Mini epi-Retinal Prosthesis (MeRP) 1: concept and design†

This paper describes the concepts and design of a prototype of a Mini epi-Retinal Prosthesis (MeRP). The MeRP is a small, optical computer consisting of an array of photodiodes. To most efficiently convert light into electrical signals, the photodiode cells have a surface area of 1 mm2 and are attached to a fibre optic plate covered with colour filters and a microlens array. The electrical current of the photodiode cells, operating in the range from picoamps to microamps, is delivered to the retinal ganglion cells (RGCs) by means of biocompatible electrically conducting polymer (ECP) strands that lie upon a non-electrically conducting polymer lead umbrella. The umbrella takes the contour of the retina. Surgical techniques are available for proper implantation. All components have been tested in a first generation prototype (FGP). Results have shown that the photodiodes produced current suitable for physiological stimulation. The means of delivering stimulation to the RGCs has been showed to be very compatible with nerve cells. Nerve growth on the ECP has been exceptional. The main advantages of the present design are: (1) it directly reflects the light intensity and visual contrast of the visual surround; (2) it is purely photovoltaic with no need for an external energy source and therefore no build-up of heat in the posterior eye segment; (3) the transmittance of the electrical signals to the retinal ganglion cells is by polymers which have proved to be biocompatible and non-toxic to the retina; (4) the output current of the individual photodiode cells is in the physiological range for stimulating retinal ganglion cells; and (5) the matrix algebra of the system is such that a reasonable spatial resolution can be expected. The usefulness of the MeRP is tested rigorously in in vitro and in vivo experiments. †Dedicated to restoring sight to the blind!

Impedance spectra of carbon black filled high‐density polyethylene composites

AbstractCarbon black (CB) filled high‐density polyethylene (HDPE) composites are prepared by ordinary blending for use as an electrical conductive polymer composite. The composite changes from an electrical insulator to a conductor as the CB content is increased from 10 to 20 wt %, which is called the percolation region. For explanatory purposes, three models, namely, “conduction via nonohmic contacting chain,” “conduction via ohmic contacting chain,” and a mixture of them corresponding to the conductions in the percolation region, high CB loading region, and limiting high CB loading are proposed by the reasonable configurations of aggregate resistance, contact resistance, gap capacitance, and joining aggregates induction. The characters of the impedance spectra based on the three models are theoretically analyzed. In order to find some link between the electrical conductivity and the CB dispersion manner in the composites, the impedance spectra of three samples, HDPE/15 wt % CB (the center of the percolation region), HDPE/25 wt % CB (a typical point in the high CB loading region), and HDPE/19 wt % CB (the limiting high CB loading region), are measured by plotting the impedance modulus and phase angle against the frequency and by drawing the Cole–Cole circle of the imaginary part and real part of the impedance modulus of each sample. The modeled approached spectra and the spectra measured on the three samples are compared and the following results are found: the measured impedance spectrum of HDPE/15 wt % CB (percolation region) is quite close to the model of conduction via nonohmic contacting chain. The character of the measured spectrum of HDPE/25 wt % CB consists of the form of the model of conduction via ohmic contacting chain. The impedance behavior of HDPE/19 wt % CB exhibits a mixture of the two models. From the comparisons, it is concluded that the electrical conducting network in the percolation region of the CB filled HDPE composite is composed of aggregate resistance, nonohmic contact resistance, and gap capacitance, and that of the high CB loading region consists of continuously joined CB aggregate chains, which are possibly wound and assume helix‐like (not straight lines) conductive chains, acting as electrical inductions as the current passes through. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1344–1350, 2005

Supercapacitors based on conducting polymers/nanotubes composites

Three types of electrically conducting polymers (ECPs), i.e. polyaniline (PANI), polypyrrole (PPy) and poly-(3,4-ethylenedioxythiophene) (PEDOT) have been tested as supercapacitor electrode materials in the form of composites with multiwalled carbon nanotubes (CNTs). The energy storage in such a type of composite combines an electrostatic attraction as well as quick faradaic processes called pseudo-capacitance. It has been shown that carbon nanotubes play the role of a perfect backbone for a homogenous distribution of ECP in the composite. It is well known that pure conducting polymers are mechanically weak, hence, the carbon nanotubes preserve the ECP active material from mechanical changes (shrinkage and breaking) during long cycling. Apart of excellent conducting and mechanical properties, the presence of nanotubes improves also the charge transfer that enables a high charge/discharge rate. For an optimal use of ECPs in electrochemical capacitors, a special electrode composition with ca. 20 wt.% of CNTs and a careful selection of the potential range is necessary. The capacitance values ranging from 100 to 330 F g −1 could be reached for different asymmetric configurations with a capacitor voltage from 0.6 to 1.8 V. It is also noteworthy that such a type of ECP/CNTs composite does not need any binding substance that is an important practical advantage.

Electric Resistance Change Method for Cure/Strain/Damage Monitoring of CFRP Laminates

This paper shows monitoring of Carbon Fiber Reinforced Polymer (CFRP) laminates by means of changes of electrical property of CFRP. Carbon fiber is electrical conductive materials and polymers are insulator. When electric current is applied to the CFRP laminates, many kinds of information are obtained such as degree of cure, applied strain and damages. For these monitoring, carbon fiber itself is adopted as a sensor. This paper shows the experimental results of the method to monitor the degree of cure, applied strain and damage. As a result, the method is shown to be effective for monitoring CFRP laminates of degree of cure, applied strain and damage.

Equipment for combinatorial electrochemical polymerization and high-throughputinvestigation of electrical properties of the synthesized polymers

The first automated system for combinatorial synthesis and high throughputinvestigation of electrical properties of conductive polymers is described. Theequipment provides a polymerization of defined mixtures of monomers into a thin layeron the addressed electrodes of an electrode array followed by measurements ofcurrent–voltage characteristics. The electrodes have an interdigital configuration,specially designed for four-point measurements. A programmed addition of gases orliquids provides automated investigation of the influence of different substances onthe synthesized polymers. The results of an experimental test of the system arepresented. This equipment can be used for synthesis and electrical characterizationof conductive polymers and multilayer polymer structures, for development ofchemical sensors, organic electronic devices and other thin film functional structures.

Electrocatalysis of Oxygen Reduction on Polypyrrole/Mixed Valence Spinel Oxide Nanoparticles

Composite electrodes based on mixed valence oxide nanoparticles (Ox) embedded in an electrically conductive polymer (ECP) were investigated toward the oxygen reduction reaction (ORR). ECP was polypyrrole (PPy), and Ox was the spinel mixed valence oxide which is known to be an electrocatalyst of the ORR in neutral and alkaline media. The main findings were that in such a composite electrode (i) the spinel lattice and the electrocatalytic activity of the oxide remained remarkably stable in acidic media where normally this oxide would be electrochemically reduced, and (ii) PPy retained its electrical conductivity at cathodic potentials where it would be normally in its insulating reduced state. Those composite electrodes sustained the ORR for hours without signs of deterioration. © 2002 The Electrochemical Society. All rights reserved.

The Microstructure and Electrical Properties of Mechanically-Alloyed Copper-Polymer Composites

Using conventional melt compounding techniques it is difficult to mix high concentrations of filler materials such as metal powders with polymers. This is particularly true when the melt viscosity of the polymer concerned is high. In solid state synthesis performed by mechanical alloying it is possible to get homogenous mixtures of high molecular weight polymers and high contents of filling material. In this work a planetary type high energy mill was used to mix high-density polyethylene (HDPE) and copper at different concentrations. The aim was to produce electrically conductive polymers. The results obtained showed that during the mechanical alloying process the high-density polyethylene and copper formed a homogeneous powder. The metal particles were homogeneously distributed within the matrix polymer particles. The shape of the polymer particles was spherical or flake-like depending on the process parameters. The shape of the copper particles inside the polymer particles was flake like and the saturation particle diameter was under 10 μm independent of the initial particle size. The microstructure of the high-density polyethylene became amorphous during the milling process. The milling time required for the formation of the amorphous phase was found to depend on the copper content. After ten hours of milling with a copper content of 50 vol.% the structure of polyethylene was completely amorphous. At copper contents of 10 vol.% even 320 hours of milling was not sufficient to produce fully amorphous HDPE. After the milling process the powders were cold compacted. The volume resistivity of the compacted polymer metal mixtures was ca. 1.0*10 11 Ωcm at a copper content of 10 vol.% and 4.0*10 -5 Ωcm at a copper content of 50 vol.%. The results show that using the mechanical alloying method it is possible to produce electrically-conductive polymers over a wide range of process and material parameters.

Theoretical prediction of three-dimensionally conjugated novel polymers with excellent mechanical and electric properties: stiffer than diamond!

Is there no more possibility to produce a novel material with elastic modulus higher than diamond, starting from conventional synthetic polymers? Through the computer-aided molecular design, a simple method of introduction of three-dimensional cross-linking into a conventional polymer crystal lattice has been found to give three-dimensionally conjugated honeycomb-like structure, which has a tremendously high Young's modulus of 700 – 1800 GPa. This value is remarkably higher than that of diamond crystal, 1050 GPa. Thus constructed structure of isotropically conjugated system has additional possibility to give the highly electrically-conductive polymer materials in three-dimensional directions.

Percolation in electrical conductive polymer / filler systems. I: Density/ filler curves according to a new thermodynamic percolation model

AbstractThis work deals with the conductivity of polymer/filler‐mixtures, with the conductive filler particles of colloid size. For the interpretation of the conductivity course in such systems Wessling recently proposed a new thermodynamical percolation model, the so‐called “dynamic boundary model.” A consequence of the dynamic boundary model is a fixed picture for some properties of the mixtures, i.e., the density should vary in a defined manner according to the theoretical assumptions of the model. The current paper first gives a short description of the percolation process according to the dynamic boundary model. Second, the derivation of the density/filler concentration curves according to the assumption of this model is given. Third, a comparison is made between calculated and experimentally determined density/filler concentration curves. It is shown that the dynamic boundary model cannot account for the experimentally observed density curves.

A high‐contrast multiplexed dot‐matrix FELCD using naphthalene‐based FELC and conductive polymer films for orientation

Abstract— A direct‐multiplexed ferroelectric liquid‐crystal display, having a contrast ratio as high as 35:1 without showing zigzag defects, has been realized by using an electrical conductive orientation polymer: a polypyrrole film together with a special material containing naphthalene‐based ferroelectric liquid crystals. The polypyrrole orientation films can effectively suppress the formation of depolarization fields, resulting in a stable memory capability and a high contrast ratio.

Electrically conducting polymers

Electrically-conducting polymers are relatively recently discovered materials that possess not only electronic conductivity variable over many orders of magnitude but other properties including ion-transport, junction effects and electrode effects allied to polymeric physical properties. Because of this they are exciting considerable research interest and under investigation for a wide range of applications within the electronics industry. This review concerns basic properties of these materials with respect to significant applications. Recent developments will be addressed and the implications towards further advances are considered. The opportunities for chemical manipulation of these materials, an important aspect of their technology, will be discussed with regard to both processability and functionalisation; the effects so produced will be discussed.

Conformational and electronic band structure analysis of a new type of high performance polybenzothiazole polymers

The energy-band structure and preferred (minimum energy) conformation of the recently synthesized polybenzothiazoles (PBT; AA and AB type), representing a new class of high-performance polymers, were determined by molecular orbital calculations. In the case of the AAPBT chain, the most stable conformation was obtained atφ1 (rotation angle about the bond joining the two bibenzothiazole moieties) = 20° andφ2 (rotation angle about the bond joining the bibenzothiazole group and thep-phenylene group) = 10°. In the case of the ABPBT chain, the corresponding minimum energy rotational angle (φ′) was found to be 20°. These conformations agree fairly well with both theoretical and experimental observations. The calculated axial band gaps were 1.94 and 2.08 eV for the AAPBT and ABPBT polymers, respectively, and these values are close to the corresponding value for polyacetylene, considered a prototype electrically-conducting polymer because of its novel electronic properties and manifold applications.

Some recent advances in materials technology

Recent advances in five key areas of materials technology are discussed. Structural and non-structural composites, electrically-conducting polymers, materials obtained by rapid quenching, new developments in hydraulic cements and photothermal solar energy conversion are reviewed.

ChemInform Abstract: STUDY OF ELECTRICALLY CONDUCTING POLYMER COMPOSITES WITH TCNQ SALTS. 1. ELECTRIC PROPERTIES OF POLYMER COMPOSITES WITH 7,7,8,8‐TETRACYANOQUINODIMETHAN SALTS

Chemischer InformationsdienstVolume 8, Issue 42 Physical Organic Chemistry ChemInform Abstract: STUDY OF ELECTRICALLY CONDUCTING POLYMER COMPOSITES WITH TCNQ SALTS. 1. ELECTRIC PROPERTIES OF POLYMER COMPOSITES WITH 7,7,8,8-TETRACYANOQUINODIMETHAN SALTS K. MIZOGUCHI, K. MIZOGUCHISearch for more papers by this authorT. KAMIYA, T. KAMIYASearch for more papers by this authorS. MATSUURA, S. MATSUURASearch for more papers by this authorE. TSUCHIDA, E. TSUCHIDASearch for more papers by this authorI. SHINOHARA, I. SHINOHARASearch for more papers by this author K. MIZOGUCHI, K. MIZOGUCHISearch for more papers by this authorT. KAMIYA, T. KAMIYASearch for more papers by this authorS. MATSUURA, S. MATSUURASearch for more papers by this authorE. TSUCHIDA, E. TSUCHIDASearch for more papers by this authorI. SHINOHARA, I. SHINOHARASearch for more papers by this author First published: October 18, 1977 https://doi.org/10.1002/chin.197742048AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume8, Issue42October 18, 1977 RelatedInformation