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1

Carrier Transport in PbS Nanocrystal Conducting Polymer Composites  

CERN Multimedia

In this paper we report the first measurements of carrier mobilities in an inorganic nanocrystal: conducting polymer composite. The composite material in question (lead sulphide nanocrystals in the conducting polymer MEH-PPV was made using a new single-pot, surfactant-free synthesis. Mobilties were measured using time of flight (ToF) and steady-state techniques. We have found that the inclusion of PbS nanocrystals in MEH-PPV both balances and markedly increases the hole and electron mobilities - the hole mobility is increased by a factor of ~105 and the electron mobility increased by ~107 under an applied bias of 5kVcm-1. These results explain why dramatic improvements in electrical conductivity and photovoltaic performance are seen in devices fabricated from these composites.

Watt, A; Rubinsztein-Dunlop, H; Meredith, P; Watt, Andrew; Eichman, Troy; Rubinsztein-Dunlop, Halina; Meredith, Paul

2004-01-01

2

Nanocrystal: Conducting Polymer Solar Cells via a New Synthetic Route  

CERN Document Server

In this letter we report photovoltaic devices fabricated from PbS nanocrystals and the conducting polymer MEH-PPV. This composite material was produced via a new single-pot synthesis which solves many of the issues associated with existing methods. Our devices have white light power conversion efficiencies under AM1.5 illumination of 0.7%.

Watt, A A R; Meredith, H; Watt, Andrew A. R.; Blake, David; Meredith, Halina Rubinsztein-Dunlop & Paul

2004-01-01

3

Conductive Polymers  

Energy Technology Data Exchange (ETDEWEB)

Electroluminescent devices such as light-emitting diodes (LED) and high-energy density batteries. These new polymers offer cost savings, weight reduction, ease of processing, and inherent rugged design compared to conventional semiconductor materials. The photovoltaic industry has grown more than 30% during the past three years. Lightweight, flexible solar modules are being used by the U.S. Army and Marine Corps for field power units. LEDs historically used for indicator lights are now being investigated for general lighting to replace fluorescent and incandescent lights. These so-called solid-state lights are becoming more prevalent across the country since they produce efficient lighting with little heat generation. Conductive polymers are being sought for battery development as well. Considerable weight savings over conventional cathode materials used in secondary storage batteries make portable devices easier to carry and electric cars more efficient and nimble. Secondary battery sales represent an $8 billion industry annually. The purpose of the project was to synthesize and characterize conductive polymers. TRACE Photonics Inc. has researched critical issues which affect conductivity. Much of their work has focused on production of substituted poly(phenylenevinylene) compounds. These compounds exhibit greater solubility over the parent polyphenylenevinylene, making them easier to process. Alkoxy substituted groups evaluated during this study included: methoxy, propoxy, and heptyloxy. Synthesis routes for production of alkoxy-substituted poly phenylenevinylene were developed. Considerable emphasis was placed on final product yield and purity.

Bohnert, G.W.

2002-11-22

4

Colloidal CuInSe2 nanocrystals: from gradient stoichiometry toward homogeneous alloyed structure mediated by conducting polymer P3HT.  

UK PubMed Central (United Kingdom)

We report, for the first time, the synthesis of colloidal copper indium selenide (CuInSe2) nanocrystals (NCs) possessing a gradient stoichiometry that is potentially tunable by the presence of a conducting polymer, i.e., poly(3-hexyl thiophene) (P3HT) in the synthesis medium. Dibenzyl ether (DBE) was used as a reaction medium, whereas copper acetylacetonate (Cu(acac)2), indium acetylacetonate (In(acac)3), and selenium powder were used as Cu, In, and Se sources, respectively. The Se precursor was tri-n-octylphosphine selenide (TOP-Se). Without the presence of P3HT, the resulting NCs consist of a p-type (Cu(1+) rich) core and an n-type (In(3+) rich) shell. Such a gradient stoichiometry was moderated to be substantially more homogeneous because the presence of P3HT is believed to have significantly reduced the reactivity difference between Cu(acac)2 and In(acac)3, as well as and their respective monomers. Furthermore, the P3HT also acts as a surface coordination species, contributing to the readily preparation of conducting polymer-NCs hybrids by a single-step synthesis. The understandings of this work can serve as a guide for design and synthesis of conducting polymer-NCs hybrids based on various ternary or quaternary compound semiconductors with different core-shell composition gradient.

Liang YN; Yu K; Yan Q; Hu X

2013-05-01

5

Semiconductor-nanocrystal/conjugated polymer thin films  

Energy Technology Data Exchange (ETDEWEB)

The invention described herein provides for thin films and methods of making comprising inorganic semiconductor-nanocrystals dispersed in semiconducting-polymers in high loading amounts. The invention also describes photovoltaic devices incorporating the thin films.

Alivisatos, A. Paul (Oakland, CA); Dittmer, Janke J. (Munich, DE); Huynh, Wendy U. (Munich, DE); Milliron, Delia (Berkeley, CA)

2010-08-17

6

The hydrodynamic size of polymer stabilized nanocrystals  

International Nuclear Information System (INIS)

For many emerging applications, nanocrystals are surface functionalized with polymers to control self-assembly, prevent aggregation, and promote incorporation into polymer matrices and biological systems. The hydrodynamic diameter of these nanoparticle-polymer complexes is a critical factor for many applications, and predicting this size is complicated by the fact that the structure of the grafted polymer at a nanocrystalline interface is not generally established. In this work we evaluate using size-exclusion chromatography the overall hydrodynamic diameter of nanocrystals (Au, CdSe, d

2007-11-28

7

Efficient polymer-nanocrystal quantum-dot photodetectors  

Science.gov (United States)

We have realized highly efficient photodetectors based on composites of the semiconducting polymer poly[2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene] and PbSe nanocrystal quantum dots. The external quantum efficiency in these devices is greater than 1 for electric fields E~7×105 V/cm. The observed photocurrent gain could be attributed to the carrier multiplication in PbSe nanocrystal quantum dots via multiple exciton generation, and the efficient charge conduction through the host polymer material. This photocurrent gain is observed only when the PbSe nanocrystal band gap is at least three times smaller than the optical energy gap of the active polymer material.

Qi, Difei; Fischbein, Michael; Drndi?, Marija; Šelmi?, Sandra

2005-02-01

8

Electrocatalysis at conducting polymers  

Energy Technology Data Exchange (ETDEWEB)

A brief review on electrocatalysis and heterogeneous catalysis at conducting polymers is presented. The topics covered include: electrocatalysis at conducting polymer electrodes (quinone-hydroquinone redox couple, organic compounds of analytical interest, various electroorganic reactions, inorganic ions), electrocatalysis at conducting polymer electrodes, modified with dispersed metals, heterogeneous catalysis and electrocatalysis at conducting polymers, doped with heteropolyanions, and various metal complexes. (orig.)

Malinauskas, A. [Inst. of Chem., Vilnius (Lithuania)

1999-11-30

9

A New Approach to the Synthesis of Nanocrystal Conjugated Polymer Composites  

CERN Document Server

A novel one pot process has been developed for the preparation of PbS nanocrystals in the conjugated polymer poly 2-methoxy,5-(2 -ethyl-hexyloxy-p-phenylenevinylene) (MEH-PPV). Current techniques for making such composite materials rely upon synthesizing the nanocrystals and conducting polymer separately, and subsequently mixing them. This multi-step technique has two serious drawbacks: templating surfactant must be removed before mixing, and co-solvent incompatibility causes aggregation. In our method, we eliminate the need for an initial surfactant by using the conducting polymer to terminate and template nanocrystal growth. Additionally, the final product is soluble in a single solvent. We present materials analysis which shows PbS nanocrystals can be grown directly in a conducting polymer, the resulting composite is highly ordered and nanocrystal size can be controlled.

Watt, A A R

2004-01-01

10

PROTON CONDUCTING POLYMERS  

UK PubMed Central (United Kingdom)

The subject invention relates to solid polymer electrolyte membranes comprising proton conducting polymers stable at temperatures in excess of 100 DEG C, the polymer being basic polymer complexed with a strong acid or an acid polymer. The invention further relates to the use of such membranes in electrolytic cells and acid fuel cells. Particularly, the invention relates to the use of polybenzimidazole as a suitable polymer electrolyte membrane.

SAVINELL ROBERT F; LITT MORTON H

11

Conducting polymer materials  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Conducting polymers represent a very interesting group of polymer materials Investigation of the synthesis, structure and properties of these materials has been the subject of considerable research efforts in the last twenty years. A short presentating of newer results obtained by investigating of t...

Jovanovi? Slobodan M.; Nestorovi? Gordana; Jeremi? Katarina B.

12

Highly conducting organometallic polymers  

Energy Technology Data Exchange (ETDEWEB)

Polymers of aromatic heterocycles such as pyrrole can be doped into states possessing conductivities nearly as high as metals. We have found that organometallic complexes of pyrrole can be chemically and electrochemically polymerized to give polymers with conductivities as high as 10 S/cm. In this poster we present synthetic routes to thin films of pyrrole-metal complexes. We will detail the structure of the material with results from IR, UV and thermal analysis studies and we will discuss the morphology of the film. We also discuss the improvements in physical properties which are possible by co-polymerization of the organometallic complexes with the pyrrole itself.

Hanks, T.W.; Martin, K. [Furman Univ., Greenville, SC (United States)

1995-12-31

13

'Stuffed' conducting polymers  

DEFF Research Database (Denmark)

Conducting polymers (CP) obtained by oxidative polymerization using iron(III) salts shrink when Fe(II) and the excess counter ions are washed out after polymerization. This phenomenon can be used to incorporate active molecules into the CP matrix via their addition to the wash liquid. In the present work we demonstrate this principle on three different CP's: polypyrrole (PPy), poly-terthiophene (PTTh) and poly(3,4-ethylenedioxy thiophene) (PEDT), using ferrocene as a model molecule to be trapped in the polymer films.

Winther-Jensen, BjØrn; Chen, J.

2005-01-01

14

High electrical conductivity antimony selenide nanocrystals and assemblies.  

UK PubMed Central (United Kingdom)

Antimony selenide is a promising thermoelectric material with a high Seebeck coefficient, but its figure of merit is limited by its low electrical conductivity. Here, we report a rapid and scalable (gram-a-minute) microwave synthesis of one-dimensional nanocrystals of sulfurized antimony selenide that exhibit 10(4)-10(10) times higher electrical conductivity than non-nanostructured bulk or thin film forms of this material. As the nanocrystal diameter increases, the nanowires transform into nanotubes through void formation and coalescence driven by axial rejection of sulfur incorporated into the nanowires from the surfactant used in our synthesis. Individual nanowires and nanotubes exhibit a charge carrier transport activation-energy of <60 meV arising from surface sulfur donor states. Nanocrystal assemblies also show high electrical conductivity, making the nanocrystals attractive building blocks to realize nanostructured thin film and bulk forms of this material for thermoelectric device applications.

Mehta RJ; Karthik C; Jiang W; Singh B; Shi Y; Siegel RW; Borca-Tasciuc T; Ramanath G

2010-11-01

15

Nanocrystals.  

Science.gov (United States)

Provided herein are compositions of functionalized, fluorescent nanocrystals comprising fluorescent nanocrystals coated with an imidazole-containing compound; compositions of functionalized, fluorescent nanocrystals comprising fluorescent nanocrystals coa...

I. Naasani

2004-01-01

16

Conductive polymer-based material  

Energy Technology Data Exchange (ETDEWEB)

Disclosed are polymer-based coatings and materials comprising (i) a polymeric composition including a polymer having side chains along a backbone forming the polymer, at least two of the side chains being substituted with a heteroatom selected from oxygen, nitrogen, sulfur, and phosphorus and combinations thereof; and (ii) a plurality of metal species distributed within the polymer. At least a portion of the heteroatoms may form part of a chelation complex with some or all of the metal species. In many embodiments, the metal species are present in a sufficient concentration to provide a conductive material, e.g., as a conductive coating on a substrate. The conductive materials may be useful as the thin film conducting or semi-conducting layers in organic electronic devices such as organic electroluminescent devices and organic thin film transistors.

McDonald, William F. (Utica, OH); Koren, Amy B. (Lansing, MI); Dourado, Sunil K. (Ann Arbor, MI); Dulebohn, Joel I. (Lansing, MI); Hanchar, Robert J. (Charlotte, MI)

2007-04-17

17

PROTON CONDUCTING COMPOUND AND PROTON CONDUCTING POLYMER  

UK PubMed Central (United Kingdom)

Disclosed is a proton conducting compound which provides proton conductivity without humidification and is suitable for electrochemical device materials such as solid electrolytes for fuel cells and electrolytes for batteries. Also disclosed is a proton conducting polymer. The proton conducting compound is composed of a melamine compound salt obtained from a melamine compound represented by the formula (1) below and a Brfnsted acid, and the proton conducting polymer is obtained by homopolymerizing or copolymerizing the melamine compound salt.In the formula, R1, R2, R3, R4 and R5 independently represent an alkyl group, an aryl group, an alkenyl group, a heterocyclic group or a hydrogen; at least one of them is a group other than hydrogen, and R2 and R3 or R4 and R5 may combine together to form a heterocyclic structure; and the alkyl group, aryl group, alkenyl group or heterocyclic group may have a substituent. When R1 is CH2=CR6-CO-O(CH2)n-, a proton conducting polymer is obtained by polymerizing the same. In this connection, R6 represents a hydrogen or an alkyl group; and n represents an integer of not less than 1.

KAWADA ATSUSHI; TASHIRO AYA

18

PROTON CONDUCTING COMPOUND AND PROTON CONDUCTING POLYMER  

UK PubMed Central (United Kingdom)

Provided is a proton-conducting compound which provides proton conductivity without humidification and is suitable for electrochemical device materials such as solid electrolytes for fuel cells and electrolytes for batteries. Provided also is a proton-conducting polymer. The proton-conducting compound is composed of a melamine compound salt obtained from a melamine compound represented by the following formula (1) and a Bronsted acid and the proton-conducting polymer is obtained by homopolymerizing or copolymerizing the melamine compound salt.; In formula (1), R 1 , R 2 , R 3 , R 4 , and R 5 each is independently an alkyl group, an aryl group, an alkenyl group, a heterocyclic group, or a hydrogen atom; at least one of them is a group other than hydrogen; R 2 and R 3 or R 4 and R 5 may join together to form a heterocyclic structure; and the alkyl group, the aryl group, the alkenyl group, or the heterocyclic group may have a substituent. A melamine compound salt wherein R 1 is CH 2 =CR 6 -CO-O(CH 2 ) n - polymerizes to yield a proton-conducting polymer. In this particular R 1 group, R 6 is hydrogen or an alkyl group and n is an integer equal to or larger than 1.

KAWADA ATSUSHI; TASHIRO AYA

19

Conducting polymer 3D microelectrodes  

DEFF Research Database (Denmark)

Conducting polymer 3D microelectrodes have been fabricated for possible future neurological applications. A combination of micro-fabrication techniques and chemical polymerization methods has been used to create pillar electrodes in polyaniline and polypyrrole. The thin polymer films obtained showed uniformity and good adhesion to both horizontal and vertical surfaces. Electrodes in combination with metal/conducting polymer materials have been characterized by cyclic voltammetry and the presence of the conducting polymer film has shown to increase the electrochemical activity when compared with electrodes coated with only metal. An electrochemical characterization of gold/polypyrrole electrodes showed exceptional electrochemical behavior and activity. PC12 cells were finally cultured on the investigated materials as a preliminary biocompatibility assessment. These results show that the described electrodes are possibly suitable for future in-vitro neurological measurements.

Sasso, Luigi; Vazquez, Patricia

2010-01-01

20

Multifunctional Composites Obtained by Incorporating Nanocrystals into Decorated PVK Polymers  

Directory of Open Access Journals (Sweden)

Full Text Available Poly(vinylcarbazole) (PVK) was decorated with surfactant group to achieve amphiphilic polymer with luminescent property. The composition and properties of the polymers were systematically investigated using FTIR, EA, TGA, UV-Vis, and PL characterizations. Different CdTe nanocrystals (NCs) prepared in aqueous medium were directly transferred to organic phase using the PVK-based polymers. The quantum yield of NCs in the composites had been improved by 50% compared with their parent aqueous solution due to the short distance from carbazole moieties to NCs, which facilitated the Förster resonant energy transfer (FRET) between them. Moreover, efficient electron transfer at the interface of NCs and polymers had been confirmed which also indicated the application in photovoltaic cell for such composites.

Haizhu Sun; Junhu Zhang; Ye Tian; Yang Ning; Hao Zhang; Jie Ju; Delong Li; Shidong Xiang; Bai Yang

2007-01-01

 
 
 
 
21

Effect of interfacial properties on polymer-nanocrystal thermoelectric transport.  

UK PubMed Central (United Kingdom)

The electrical behavior of a conducting-polymer/inorganic-nanowire composite is explained with a model in which carrier transport occurs predominantly through a highly conductive volume of polymer that exists at the polymer-nanowire interface. This result highlights the importance of controlling nanoscale interfaces for thermoelectric materials, and provides a general route for improving carrier transport in organic/inorganic composites.

Coates NE; Yee SK; McCulloch B; See KC; Majumdar A; Segalman RA; Urban JJ

2013-03-01

22

Ultrabroadband terahertz conductivity of Si nanocrystal films  

DEFF Research Database (Denmark)

The terahertz conductivity of silicon nanoparticles embedded in glass with varying density is studied with ultra-broadband terahertz spectroscopy on picosecond time scales following fs optical excitation. The transition from relatively isolated charge carriers to densities which allow inter-particle transport is clearly observed. For the times immediately following carrier injection, we observe Drude-like long range transport that is rapidly replaced with a localized response on picosecond time scales. The localized response can be very well described by a phenomenological Drude-Smith model, verifying the applicability of this simple model to the conductivity of nanoparticle ensembles over the entire THz spectral window.

Cooke, D. G.; Meldrum, A.

2012-01-01

23

Superstructures of PbS nanocrystals in a conjugated polymer and the aligning role of oxidation  

International Nuclear Information System (INIS)

We present a method to directly align PbS nanocrystals in micron-sized superstructures within a conjugated polymer. First, lead sulfide nanocrystals are directly synthesized in a MEH-PPV suspension via a single pot, surfactant-free method. Post-synthesis precipitation of the composite solution involving mild oxidation of the nanocrystals results in the formation of nanocrystal-polymer and nanocrystal-oxide superstructures. Detailed TEM is used to study the crystallographic nature of these structures and the roles of polymer and lead sulfate. An epitaxial relationship between lead sulfide and lead sulfate at the nanoscale is shown, giving insight into the oxidation rates of the PbS nanocrystals' facets.

2009-11-04

24

Electrically conductive polymer concrete overlays  

Energy Technology Data Exchange (ETDEWEB)

The use of cathodic protection to prevent the corrosion of reinforcing steel in concrete structures has been well established. Application of a durable, skid-resistant electrically conductive polymer concrete overlay would advance the use of cathodic protection for the highway industry. Laboratory studies indicate that electrically conductive polymer concrete overlays using conductive fillers, such as calcined coke breeze, in conjunction with polyester or vinyl ester resins have resistivities of 1 to 10 ohm-cm. Both multiple-layer and premixed mortar-type overlays have been made. Shear bond strengths of the conductive overlays to concrete substrates vary from 600 to 1300 psi, with the premixed overlays having bond strengths 50 to 100% higher than the multiple-layer overlays.

Fontana, J.J.; Webster, R.P.

1984-08-01

25

Unified Hamiltonian for conducting polymers  

International Nuclear Information System (INIS)

Two transferable physical parameters are incorporated into the Su-Schrieffer-Heeger Hamiltonian to model conducting polymers beyond polyacetylene: the parameter ? scales the electron-phonon coupling strength in aromatic rings and the other parameter ? specifies the heterogeneous core charges. This generic Hamiltonian predicts the fundamental band gaps of polythiophene, polypyrrole, polyfuran, poly-(p-phenylene), poly-(p-phenylene vinylene), and polyacenes, and their oligomers of all lengths, with an accuracy exceeding time-dependent density functional theory. Its computational costs for moderate-length polymer chains are more than eight orders of magnitude lower than first-principles approaches. (paper)

2011-11-16

26

The workshop on conductive polymers: Final report  

Energy Technology Data Exchange (ETDEWEB)

Reports are made by groups on: polyacetylene, polyphenylene, polyaniline, and related systems; molecular, crystallographic, and defect structures in conducting polymers; heterocyclic polymers; synthesis of new and improved conducting polymers; future applications possibilities for conducting polymers; and challenges for improved understanding of properties. (DLC)

1985-01-01

27

Water-soluble conductive polymers  

Energy Technology Data Exchange (ETDEWEB)

Polymers which are soluble in water and are electrically conductive. The monomer repeat unit is a thiophene or pyrrole molecule having an alkyl group substituted for the hydrogen atom located in the beta position of the thiophene or pyrrole ring and having a surfactant molecule at the end of the alkyl chain. Polymers of this class having 8 or more carbon atoms in the alkyl chain exhibit liquid crystalline behavior, resulting in high electrical anisotropy. The monomer-to-monomer bonds are located between the carbon atoms which are adjacent to the sulfur or nitrogen atoms. The number of carbon atoms in the alkyl group may vary from 1 to 20 carbon atoms. The surfactant molecule consists of a sulfonate group, or a sulfate group, or a carboxylate group, and hydrogen or an alkali metal. Negative ions from a supporting electrolyte which may be used in the electrochemical synthesis of a polymer may be incorporated into the polymer during the synthesis and serve as a dopant to increase the conductivity.

Aldissi, Mahmoud (Sante Fe, NM)

1989-01-01

28

Water-soluble conductive polymers  

Energy Technology Data Exchange (ETDEWEB)

Polymers which are soluble in water and are electrically conductive. The monomer repeat unit is a thiophene or pyrrole molecule having an alkyl group substituted for the hydrogen atom located in the beta position of the thiophene or pyrrole ring and having a surfactant molecule at the end of the alkyl chain. Polymers of this class having 8 or more carbon atoms in the alkyl chain exhibit liquid crystalline behavior, resulting in high electrical anisotropy. The monomer-to-monomer bonds are located between the carbon atoms which are adjacent to the sulfur or nitrogen atoms. The number of carbon atoms in the alkyl group may vary from 1 to 20 carbon atoms. The surfactant molecule consists of a sulfonate group, or a sulfate group, or a carboxylate group, and hydrogen or an alkali metal. Negative ions from a supporting electrolyte which may be used in the electrochemical synthesis of a polymer may be incorporated into the polymer during the synthesis and serve as a dopant to increase the conductivity.

Aldissi, Mahmoud (Sante Fe, NM)

1990-01-01

29

Hybrid nanocrystal/polymer solar cells based on tetrapod-shaped CdSexTe1-x nanocrystals  

International Nuclear Information System (INIS)

A series of ternary tetrapodal nanocrystals of CdSexTe1-x with x = 0 (CdTe), 0.23, 0.53, 0.78, 1 (CdSe) were synthesized and used to fabricate hybrid nanocrystal/polymer solar cells. Herein, the nanocrystals acted as electron acceptors, and poly(2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene) (MEH-PPV) was used as an electron donor. It was found that the open circuit voltage (Voc), short-circuit current (Jsc) and power conversion efficiency (?) of the devices all increased with increasing Se content in the CdSexTe1-x nanocrystals under identical experimental conditions. The solar cell based on the blend of tetrapodal CdSe nanocrystals and MEH-PPV (9:1 w/w) showed the highest power conversion efficiency of 1.13% under AM 1.5, 80 mW cm-2, and the maximum incident photon to converted current efficiency (IPCE) of the device reached 47% at 510 nm. The influence of nanocrystal composition on the photovoltaic properties of the hybrid solar cells was explained by the difference of the band level positions between MEH-PPV and the nanocrystals.

1000-01-00

30

Electrically conductive polymer concrete coatings  

Energy Technology Data Exchange (ETDEWEB)

A sprayable electrically conductive polymer concrete coating for vertical d overhead applications is described. The coating is permeable yet has low electrical resistivity (<10 ohm-cm), good bond strength to concrete substrates, and good weatherability. A preferred formulation contains about 60 wt % calcined coke breeze, 40 wt % vinyl ester with 3.5 wt % modified bentonite clay. Such formulations apply evenly and provide enough rigidity for vertical or overhead structures so there is no drip or sag.

Fontana, Jack J. (Shirley, NY); Elling, David (Centereach, NY); Reams, Walter (Shirley, NY)

1990-01-01

31

Optical Gain from InAs Nanocrystal Quantum Dots in a Polymer Matrix  

CERN Document Server

We report on the first observation of optical gain from InAs nanocrystal quantum dots emitting at 1.55 microns based on a three-beam, time resolved pump-probe technique. The nanocrystals were embedded into a transparent polymer matrix platform suitable for the fabrication of integrated photonic devices.

Chen, G; Fuchs, D; Vilan, S; Aharoni, A; Banin, U; Chen, Gang; Rapaport, Ronen; Fuchs, Dan; Vilan, Sahar; Aharoni, Assaf; Banin, Uri

2005-01-01

32

Comparing proton conductivity of polymer electrolytes by percent conducting volume  

Energy Technology Data Exchange (ETDEWEB)

Proton conductivity of sulfonated polymers plays a key role in polymer electrolyte membrane fuel cells. Mass based water uptake and ion exchange capacity of sulfonated polymers have been failed to correlating their proton conductivity. In this paper, we report a length scale parameter, percent conductivity volume, which is rather simply obtained from the chemical structure of polymer to compare proton conductivity of wholly aromatic sulfonated polymer perflurosulfonic acid. Morphology effect on proton conductivity at lower RH conditions is discussed using the percent conductivity volume parameter.

Kim, Yu Seung [Los Alamos National Laboratory; Pivovar, Bryan [NREL

2009-01-01

33

Enhanced Semiconductor Nanocrystal Conductance via Solution Grown Contacts  

Energy Technology Data Exchange (ETDEWEB)

We report a 100,000-fold increase in the conductance of individual CdSe nanorods when they are electrically contacted via direct solution phase growth of Au tips on the nanorod ends. Ensemble UV-Vis and X-Ray photoelectron spectroscopy indicate this enhancement does not result from alloying of the nanorod. Rather, low temperature tunneling and high temperature (250-400 K) thermionic emission across the junction at the Au contact reveal a 75percent lower interface barrier to conduction compared to a control sample. We correlate this barrier lowering with the electronic structure at the Au-CdSe interface. Our results emphasize the importance of nanocrystal surface structure for robust device performance and the advantage of this contact method.

Sheldon, Matthew T.; Trudeau, Paul-Emile; Mokari, Taleb; Wang, Lin-Wang; Alivisatos, A. Paul

2009-08-19

34

Advances in inherently conducting polymers  

Energy Technology Data Exchange (ETDEWEB)

The discovery of polyacetylene as the prototype material led to extensive research on its synythesis and characterization. The techniques that emerged as the most important and promising ones are those that dealt with molecular orientation and that resulted in conductivities almost as high as that of copper. The study of dozens of other materials followed. Interest in conducting polymers stems from their nonclassical optical and electronic properties as well as their potential technological applications. However, some of the factors currently limiting their use are the lack of long-term stability and the need to develop conventional low-cost techniques for easy processing. Therefore, research was extended toward solving these problems, and progress has been recently made in that direction. The synthesis of new materials such as stable and easily processable alkylthiophenes, water-soluble polymers, and multicomponent systems, including copolymers and composites, constitutes an important step forward in the area of synthetic metals. However, a full understanding of materials chemistry and properties requires more work in the years to come. Although, few small-scale applications have proven to be successful, long-term stability and applicability tests are needed before their commercial use becomes reality.

Aldissi, M.

1987-09-01

35

Molecular and supramolecular orientation in conducting polymers  

Energy Technology Data Exchange (ETDEWEB)

Intrinsic anisotropy in electrical and optical properties of conducting polymers constitutes a unique aspect that derives ..pi..-electron delocalization along the polymer backbone and from the weak inter-chain interaction. To acquire such an intrinsic property, conducting polymers have to be oriented macroscopically and microscopically (at the chain level). A review of the various techniques, including stretch-alignment of the polymer and of precursor polymers, polymerization in ordered media, i.e., in a liquid crystal solvent, and synthesis of liquid crystalline conducting polymers will be given. 29 refs.

Aldissi, M.

1987-01-01

36

Properties of size-tuned PbS nanocrystals stabilized in a polymer template  

International Nuclear Information System (INIS)

Nanoclusters of PbS embedded in polymer matrices have recently been shown to have interesting optical properties with the capability of tuning the effective band gap over a wide spectral range. The results of a systematic investigation of the preparation and characterization of size-tuned PbS nanocrystals stabilized in the polymer nanotemplate of Nafion and their size-dependent physical properties are presented in this paper. These nanocrystals exhibit large characteristic blueshift in optical absorption from the bulk absorption onset value of 3020 nm. XRD and HRTEM measurements indicate the presence of PbS nanocrystals in the size range of 2-6 nm, in the regime of strong quantum confinement. Thermal and electrical properties of the polymer are found to be influenced to a great extent by the embedded PbS nanocrystals.

2007-06-05

37

Direct writing of conducting polymers.  

Science.gov (United States)

Described herein is a new printing method-direct writing of conducting polymers (CPs)-based on pipette-tip localized continuous electrochemical growth. A single barrel micropipette containing a metal wire (Pt) is filled with a mixture of monomer, supporting electrolyte, and an appropriate solvent. A droplet at the tip of the pipette contacts the substrate, which becomes the working electrode of a micro-electrochemical cell confined to the tip droplet and the pipette. The metallic wire in the pipette acts as both counter and reference electrode. Electropolymerization forms the CP on the working electrode in a pattern controlled by the movement of the pipette. In this study, various width poly(pyrrole) 2D and 3D structures are extruded and characterized in terms of microcyclic voltammetry, Raman spectroscopy, and scanning electron microscopy. PMID:23857715

Aydemir, Nihan; Parcell, James; Laslau, Cosmin; Nieuwoudt, Michel; Williams, David E; Travas-Sejdic, Jadranka

2013-07-16

38

Conducting Polymers for Neutron Detection  

Energy Technology Data Exchange (ETDEWEB)

Conjugated polymers have emerged as an attractive technology for large-area electronic applications. As organic semiconductors, they can be used to make large-area arrays of diodes or transistors using fabrication techniques developed for polymer coatings, such as spraying and screen-printing. We have demonstrated both neutron and alpha detection using diodes made from conjugated polymers and have done preliminary work to integrate a boron carbide layer into the conventional polymer device structure to capture thermal neutrons. The polymer devices appear to be insensitive to gamma rays, due to their small physical thickness and low atomic number.

Clare Kimblin, Kirk Miller, Bob Vogel, Bill Quam, Harry McHugh, Glen Anthony, Steve Jones, Mike Grover

2007-12-01

39

Conducting Polymers for Neutron Detection  

International Nuclear Information System (INIS)

[en] Conjugated polymers have emerged as an attractive technology for large-area electronic applications. As organic semiconductors, they can be used to make large-area arrays of diodes or transistors using fabrication techniques developed for polymer coatings, such as spraying and screen-printing. We have demonstrated both neutron and alpha detection using diodes made from conjugated polymers and have done preliminary work to integrate a boron carbide layer into the conventional polymer device structure to capture thermal neutrons. The polymer devices appear to be insensitive to gamma rays, due to their small physical thickness and low atomic number

2007-01-01

40

Percolation conduction in polymer composites containing polypyrrole coated insulating polymer fiber and conducting polymer  

Energy Technology Data Exchange (ETDEWEB)

Electrical conductivity of polymer composite containing insulating polymer fiber coated with thin polypyrrole layer has been found to increase remarkably by more than ten orders of magnitude above some threshold concentration. The activation energy of the electrical conductivity also changes drastically above this threshold. Thermoelectric power at concentration above this threshold is nearly the same with that of doped polypyrrole. The threshold concentration has been found to be dependent on the length of fiber remarkably. Longer length of fiber exhibits lower threshold concentration. These results are discussed in terms of percolation theory by taking the shape of fiber into consideration. Percolation conduction is also observed in other composites made of insulating polymers containing conducting polymers such as polyaniline. (orig.)

Yin, X.H. [Faculty of Engineering, Osaka University, Yamada-Oka, Suita, Osaka 565 (Japan); Kobayashi, K. [Faculty of Engineering, Osaka University, Yamada-Oka, Suita, Osaka 565 (Japan); Yoshino, K. [Faculty of Engineering, Osaka University, Yamada-Oka, Suita, Osaka 565 (Japan); Yamamoto, H. [Central Research Laboratory, Japan Carlit Co., Ltd,. 2470 Honda, Shibukawa, Gunma (Japan); Watanuki, T. [Central Research Laboratory, Japan Carlit Co., Ltd,. 2470 Honda, Shibukawa, Gunma (Japan); Isa, I. [Central Research Laboratory, Japan Carlit Co., Ltd,. 2470 Honda, Shibukawa, Gunma (Japan)

1995-03-01

 
 
 
 
41

Bridge Hopping on Conducting Polymers in Solution  

CERN Multimedia

Configurational fluctuations of conducting polymers in solution can bring into proximity monomers which are distant from each other along the backbone. Electrons can hop between these monomers across the "bridges" so formed. We show how this can lead to (i) a collapse transition for metallic polymers, and (ii) to the observed dramatic efficiency of acceptor molecules for quenching fluorescence in semiconducting polymers.

Hone, D W; Hone, Daniel W.; Orland, Henri

2001-01-01

42

Nanostructured polymer membranes for proton conduction  

Energy Technology Data Exchange (ETDEWEB)

Polymers having an improved ability to entrain water are characterized, in some embodiments, by unusual humidity-induced phase transitions. The described polymers (e.g., hydrophilically functionalized block copolymers) have a disordered state and one or more ordered states (e.g., a lamellar state, a gyroid state, etc.). In one aspect, the polymers are capable of undergoing a disorder-to-order transition while the polymer is exposed to an increasing temperature at a constant relative humidity. In some aspects the polymer includes a plurality of portions, wherein a first portion forms proton-conductive channels within the membrane and wherein the channels have a width of less than about 6 nm. The described polymers are capable of entraining and preserving water at high temperature and low humidity. Surprisingly, in some embodiments, the polymers are capable of entraining greater amounts of water with the increase of temperature. The polymers can be used in Polymer Electrolyte Membranes in fuel cells.

Balsara, Nitash Pervez; Park, Moon Jeong

2013-06-18

43

Prospects of conducting polymers in biosensors  

Energy Technology Data Exchange (ETDEWEB)

Applications of conducting polymers to biosensors have recently aroused much interest. This is because these molecular electronic materials offer control of different parameters such as polymer layer thickness, electrical properties and bio-reagent loading, etc. Moreover, conducting polymer based biosensors are likely to cater to the pressing requirements such as biocompatibility, possibility of in vivo sensing, continuous monitoring of drugs or metabolites, multi-parametric assays, miniaturization and high information density. This paper deals with the emerging trends in conducting polymer based biosensors during the last about 5 years.

Malhotra, Bansi D. [Biomolecular Electronics and Conducting Polymer Research Group, National Physical Laboratory, Dr. K.S. Krishnan Marg, New Delhi 110012 (India)]. E-mail: bansi@mail.nplindia.ernet.in; Chaubey, Asha [Regional Research Laboratory, Jammu (India); Singh, S.P. [Biomolecular Electronics and Conducting Polymer Research Group, National Physical Laboratory, Dr. K.S. Krishnan Marg, New Delhi 110012 (India)

2006-09-18

44

Prospects of conducting polymers in biosensors  

International Nuclear Information System (INIS)

[en] Applications of conducting polymers to biosensors have recently aroused much interest. This is because these molecular electronic materials offer control of different parameters such as polymer layer thickness, electrical properties and bio-reagent loading, etc. Moreover, conducting polymer based biosensors are likely to cater to the pressing requirements such as biocompatibility, possibility of in vivo sensing, continuous monitoring of drugs or metabolites, multi-parametric assays, miniaturization and high information density. This paper deals with the emerging trends in conducting polymer based biosensors during the last about 5 years

2006-09-18

45

Biomimetic conducting polymer-based tissue scaffolds.  

UK PubMed Central (United Kingdom)

Conducting polymer-based materials are promising for application as tissue scaffolds for the replacement or restoration of damaged or malfunctioning tissues, because a variety of tissues respond to electrical stimulation. This review focuses on conducting polymer-based materials with biomimetic chemical, mechanical and topological properties, and recent progress toward the fabrication of clinically relevant tissue scaffolds is highlighted.

Hardy JG; Lee JY; Schmidt CE

2013-04-01

46

A Platform for Functional Conductive Polymers  

DEFF Research Database (Denmark)

Conductive polymers have been studied extensively during recent years. In order to broaden the application field of conductive polymers different methods have been tested and recently an azide functional poly(3,4-ethylenedioxythiophene) (PEDOT-N3) was developed(1, 2). The azide functional conductive polymer can be postpolymerization functionalized to introduce a large number of functionalities through click chemistry(3). Through selection of reaction conditions it is possible control the depth of the reaction into the polymer film to the upper surface or the entire film(4). Thus a conductive polymer can be prepared with a subsurface layer of highly conductive polymer where only the upper surface has been grafted with functional groups to ensure selectivity of the surface layer for e.g. interaction with specific biospecies. The conductive polymer can be patterned using selective etching, which enables preparation of e.g. interdigitated electrodes or other surface structures. The electrodes have been applied in controlled localized click reactions through ”electroclick” reactions(5). This enables preparation of both highly functional electrodes as well as gradient surfaces(6). The system is very versatile in all dimensions and structures and allows for preparation of conductive polymers with very specific properties. Recent results on a grafting from method to modify the surface properties will be presented.

Daugaard, Anders Egede; Hoffmann, Christian

47

Morphology in electrochemically grown conducting polymer films  

Energy Technology Data Exchange (ETDEWEB)

A conducting polymer film with an improved space filling is formed on a metal electrode surface. A self-assembling monolayer is formed directly on the metal surface where the monolayer has a first functional group that binds to the metal surface and a second chemical group that forms a chemical bonding site for molecules forming the conducting polymer. The conducting polymer is then conventioonally deposited by electrochemical deposition. In one example, a conducting film of polyaniline is formed on a gold electrode surface with an intermediate monolayer of p-aminothiophenol.

Rubinstein, Israel (Rishon-Letzion, IL); Gottesfeld, Shimshon (Los Alamos, NM); Sabatani, Eyal (Rehovot, IL)

1992-01-01

48

“Electro-Click” on Conducting Polymer Films  

DEFF Research Database (Denmark)

An azide substituted 3,4-ethylenedioxythiophene monomer is polymerised to yield a PEDOT like polymer with available azide groups (Figure 1). The azide groups enable post polymerization functionalization of the conducting polymer using a 1,3 dipolar cycloaddition reaction – also denoted “click chemistry”. This facilitates the addition of compounds that can otherwise not withstand the polymerization conditions. Several biological active molecules have been attached and tested on the films. Furthermore conducting polymer microelectrodes can electrochemically generate the catalyst required for their own functionalization with high spatial resolution. Interdigitated microelectrodes prepared from the azide-containing conducting polymer were selectively functionalized in sequence by two alkyne-modified fluorophores by control of the applied potentials. “Electro-click” on conducting polymer films shows the potential for being an important platform for biological devices and sensors.

Hansen, Thomas Steen; Lind, Johan Ulrik

49

Conductivity studies on solid polymer electrolytes  

Energy Technology Data Exchange (ETDEWEB)

This thematic lecture addresses electrochemical conductivity techniques for the study of solid polymer electrolytes. Types of conductivity are discussed first, followed by an outline of the feature, applicability, and validity of DC and AC conductivity measurements. Techniques for the identification of the individual species responsible for conduction are then briefly reviewed. (orig.).

Sequeira, C.A.C. [Instituto Superior Tecnico, Lisbon (Portugal); Plancha, M.J.C. [Instituto Superior Tecnico, Lisbon (Portugal); Araujo, L.P.S. [Instituto Superior Tecnico, Lisbon (Portugal)

1994-01-01

50

Dual function conducting polymer diodes  

Science.gov (United States)

Dual function diodes based on conjugated organic polymer active layers are disclosed. When positively biased the diodes function as light emitters. When negatively biased they are highly efficient photodiodes. Methods of preparation and use of these diodes in displays and input/output devices are also disclosed.

Heeger, Alan J. (Santa Barbara, CA); Yu, Gang (Goleta, CA)

1996-01-01

51

Electrochemical sensor based on conductive polymer electrolyte  

Energy Technology Data Exchange (ETDEWEB)

A novel conductive polymer film has been incorporated into an electrochemical sensor for the determination of toxic gases. The conductive film consists of an inert polymer, a completing agent, and a salt. A variety of gases can be determined with this sensor. The specific detection of sulfuryl fluoride (SO{sub 2}F{sub 2}) in air will be discussed as an example of the capability and flexibility of technology.

Ribes, C.; Cisneros, B.; Noding, S.A.; Ribes, A.J. [Dow Chemical Co., Plaquemine, LA (United States)

1995-12-31

52

Conductive polymer switch for controlling superconductivity  

International Nuclear Information System (INIS)

The preparation of a hybrid conducting polymer/high-temperature superconductor device consisting of a polypyrrole coated YBa2Cu3O7-? microbridge is reported. Electrochemical techniques are exploited to alter the oxidation state of the polymer and, in doing so, it is found for the first time that superconductivity can be modulated in a controllable and reproducible fashion by a polymer layout. Whereas the neutral (insulating) polypyrrole only slightly influences the electrical properties of the underlying YBa2Cu3O7-? film, the oxidized (conductive) polymer depresses Tc by up to 50K. In a similar fashion, the oxidation state of the polymer is found to reversibly modulate the magnitude of Jc, the superconducting critical current. Thus, a new type of molecule switch for controlling superconductivity is demonstrated.

1994-01-01

53

Processing of Polymer Nanocomposites Reinforced with Polysaccharide Nanocrystals  

Directory of Open Access Journals (Sweden)

Full Text Available Aqueous suspensions of polysaccharide (cellulose, chitin or starch) nanocrystals can be prepared by acid hydrolysis of biomass. The main problem with their practical use is related to the homogeneous dispersion of these nanoparticles within a polymeric matrix. Water is the preferred processing medium. A new and interesting way for the processing of polysaccharide nanocrystals-based nanocomposites is their transformation into a co-continuous material through long chain surface chemical modification. It involves the surface chemical modification of the nanoparticles based on the use of grafting agents bearing a reactive end group and a long compatibilizing tail.

Alain Dufresne

2010-01-01

54

Conductive polymers formed by ion implantation  

Energy Technology Data Exchange (ETDEWEB)

Conductive materials are formed by implanting high energy ions (30 keV to 300 keV) into rigid backboned polymers, such as poly (p-phenylene sulfide); conductivities on the order of 10-/sup 3/ (ohm-cm)-/sup 1/ are demonstrated and the materials remain stable over periods as long as a year.

Mazurek, H.; Abel, J.S.; Day, D.R.; Maby, E.W.

1985-01-01

55

Mixed ionic and electronic conductivity in polymers  

Energy Technology Data Exchange (ETDEWEB)

New polymer films were synthesized that are mixed ionic-electronic conductors. Preliminary ion transport measurements have been made on these materials in the reduced state where electronic conductivity is negligible. We also have made preliminary measurements of switching times for these materials. Theoretical studies have been performed ion pairing in insulating and electronically conducting films.

Shriver, D.F.

1991-06-01

56

Coordination power adjustment of surface-regulating polymers for shaping gold polyhedral nanocrystals.  

UK PubMed Central (United Kingdom)

PVP (poly(vinyl pyrrolidone)) is a common polymer that behaves as a surface-regulating agent that shapes metal nanocrystals in the polyol process. We have used different polymers containing tertiary amide groups, namely PVCL (poly(vinyl caprolactam)) and PDMAm (poly(N,N-dimethyl acrylamide)), for the synthesis of gold polyhedrons, including octahedrons, cuboctahedrons, cubes, and higher polygons, under the present polyol reaction conditions. The basicity and surface coordination power of the polymers are in the order of PVCL, PVP, and PDMAm. A correlation is observed between the coordination power of the polymers and the resulting gold nanocrystal size. Strong coordination and electron donation from the polymer functional groups to the gold surface restrict particle growth rates, which leads to small nanocrystals. The use of PVCL can yield gold polyhedral structures with small sizes, which cannot be achieved in the reactions with PVP. Simultaneous hydrolysis of the amide group in PDMAm leads to carboxylate functionality, which is very useful for generating chemical and bioconjugates through the formation of ester and amide bonds.

Lee SJ; Park G; Seo D; Ka D; Kim SY; Chung IS; Song H

2011-07-01

57

Processing of Polymer Nanocomposites Reinforced with Polysaccharide Nanocrystals  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Aqueous suspensions of polysaccharide (cellulose, chitin or starch) nanocrystals can be prepared by acid hydrolysis of biomass. The main problem with their practical use is related to the homogeneous dispersion of these nanoparticles within a polymeric matrix. Water is the preferred processing mediu...

Alain Dufresne

58

Conducting polymer membranes as intelligent separation systems  

Energy Technology Data Exchange (ETDEWEB)

Conducting electroactive polymers such as polypyrroles, are emerging as excellent materials in which to base a generic technology for the development of intelligent material systems. They are easy to make and many different chemistries may be built in during synthesis by varying the polymer(s) used and the counterions incorporated. However, the unique feature about them is that they have dynamic chemical and physical properties which may be manipulated via changing the redox states after synthesis. This paper illustrates their potential using recent work on developing a new electro-membrane separation technology using free-standing polypyrrole films. These systems are shown to be capable of a high degree of permselectivity and controllable transport that may be turned on and off by application of potential to the conducting polymer membrane.

Price, W.E.; Wallace, G.G. [Univ. of Wollongong, New South Wales (Australia)

1994-12-31

59

Conducting polymers: Synthesis and industrial applications  

Energy Technology Data Exchange (ETDEWEB)

The Conducting Polymer project funded by the AIM Program has developed new methods for the synthesis of conducting polymers and evaluated new industrial applications for these materials which will result in significant reductions in energy usage or industrial waste. The applications specifically addressed during FY 1996 included two ongoing efforts on membranes for gas separation and on electrochemical capacitors and a third new application: electrochemical reactors (ECRs) based on polymeric electrolytes. As a gas separation membrane, conducting polymers offer high selectivity and the potential to chemically or electrically adapt the membrane for specific gas combinations. Potential energy savings in the US for this application are estimated at 1 to 3 quads/yr. As an active material in electrochemical capacitors, electronically conducting polymers have the potential of storing large amounts of electric energy in low cost materials. Potential energy savings estimated at 1 quad/yr would result from introduction of electrochemical capacitors as energy storage devices in power trains of electric and hybrid vehicles, once such vehicles reach 20% of the total transportation market in the US. In the chlor-alkali industry, electrochemical reactors based on polymer electrolyte membranes consume around 1 % of the total electric power in the US. A new activity, started in FY 1996, is devoted to energy efficient ECRs. In the case of the chlor-alkali industry, energy savings as high as 50% seem possible with the novel ECR technology demonstrated by the author in 1996.

Gottesfeld, S. [Los Alamos National Lab., NM (United States)

1997-04-01

60

Charge separation and transport in conjugated-polymer/semiconductor-nanocrystal composites studied by photoluminescence quenching and photoconductivity  

International Nuclear Information System (INIS)

[en] We study the processes of charge separation and transport in composite materials formed by mixing cadmium selenide or cadmium sulfide nanocrystals with the conjugated polymer poly(2-methoxy,5-(2'-ethyl)-hexyloxy-p-phenylenevinylene) (MEH-PPV). When the surface of the nanocrystals is treated so as to remove the surface ligand, we find that the polymer photoluminescence is quenched, consistent with rapid charge separation at the polymer/nanocrystal interface. Transmission electron microscopy of these quantum/conjugated-polymer composites shows clear evidence for phase segregation with length scales in the range 10 endash 200 nm, providing a large area of interface for charge separation to occur. Thin-film photovoltaic devices using the composite materials show quantum efficiencies that are significantly improved over those for pure polymer devices, consistent with improved charge separation. At high concentrations of nanocrystals, where both the nanocrystal and polymer components provide continuous pathways to the electrodes, we find quantum efficiencies of up to 12%. We describe a simple model to explain the recombination in these devices, and show how the absorption, charge separation, and transport properties of the composites can be controlled by changing the size, material, and surface ligands of the nanocrystals. copyright 1996 The American Physical Society

1996-01-01

 
 
 
 
61

Structural and Electrical Study of Conducting Polymers  

Science.gov (United States)

Pure and oxalic acid doped conducting polymers (polyaniline and polypyrrole) were chemically synthesized using ammonium persulfate (APS) as an oxidant. These samples were characterized through Scanning Electron Microscopy (SEM), which provides information about the surface topography of polymers. I-V characteristics have been recorded at room temperature as well as in the temperature range from 313 K to 463 K. So obtained characteristic curves were found to be linear. Temperature dependence of conductivity suggests a semiconducting nature in polyaniline samples with increase in temperature, whereas oxalic acid doped polypyrrole sample suggests a transition from semiconducting to metallic nature with the increase of temperature.

Shaktawat, Vinodini; Dixit, Manasvi; Saxena, N. S.; Sharma, Kananbala

2010-06-01

62

Electrochemical characterization of new conducting polymer electrolytes  

Energy Technology Data Exchange (ETDEWEB)

Prepared with bis-amino PEO/PPO copolymers, with and without amino PEO oligomers, and the cross-linking agent butanediol diglycidyl ether, a new series of cross-linked polymer electrolytes were investigated for their ionic conductivity and for the electrochemical properties of lithium cycleability and lithium polymer electrolyte compatibility. Room-temperature conductivity was found to be two order of magnitude higher than that of 'conventional' PEO-based electrolytes; compatibility with metallic lithium proved to be fairly good. (orig.)

Arbizzani, C. (Dipt. di Chimica ' G. Ciamician' , Univ. di Bologna (Italy)); Mastragostino, M. (Dipt. di Chimica ' G. Ciamician' , Univ. di Bologna (Italy)); Meneghello, L. (Dipt. di Chimica ' G. Ciamician' , Univ. di Bologna (Italy)); Andrieu, X. (Alcatel Alsthom Recherche, 91 - Marcoussis (France)); Vicedo, T. (Alcatel Alsthom Recherche, 91 - Marcoussis (France))

1993-06-01

63

Conductivity of carbon nanotube polymer composites  

Energy Technology Data Exchange (ETDEWEB)

Dissipative Particle Dynamics (DPD) simulations were used to investigate methods of controlling the assembly of percolating networks of carbon nanotubes (CNTs) in thin films of block copolymer melts. For suitably chosen polymers the CNTs were found to spontaneously self-assemble into topologically interesting patterns. The mesoscale morphology was projected onto a finite-element grid and the electrical conductivity of the films computed. The conductivity displayed non-monotonic behavior as a function of relative polymer fractions in the melt. Results are compared and contrasted with CNT dispersion in small-molecule fluids and mixtures.

Wescott, J T; Kung, P; Maiti, A

2006-11-20

64

How conductive polymer/nano-conductive filler composites can be?  

Science.gov (United States)

How conductive can polymer/filler composites be? It was thought the conductivity of composites could be increased by reducing the sizes of the fillers or increasing their aspect ratios, for example, by using carbon nanotubes. Invention of numerous conductive nanomaterials provides opportunity to verify this idea and to achieve higher conductivity. However, the highest conductivity of composites achieved was just a few percents of that of bulk materials of the fillers, regardless whether the filler was silver micron particles, platinum nano particles, carbon nano particles, or carbon nano tubes. The conductivity of filler-based composite is intrinsically limited by the micro-contact between the conductive fillers. Reducing the filler size or increasing aspect ratio did not yield significant improvements in conductivity although percolation may occur earlier.

Lyu, Suping; Untereker, Darrel; Schley, James

2007-03-01

65

Effect of novel stabilizers--cationic polymers on the particle size and physical stability of poorly soluble drug nanocrystals.  

UK PubMed Central (United Kingdom)

UNLABELLED: In this study, a novel class of stabilizer, cationic polymer, was introduced into the system of nanocrystals. Taking itraconazole as a poorly soluble model drug, the influence of three cationic polymers-chitosan, N-trimethyl chitosan, and polyethyleneimine-on the properties of the nanocrystals prepared by high-pressure homogenization method was investigated. Physicochemical properties of the nanoparticles were characterized. It was demonstrated that the cationic polymers could act as both an electrostatic and steric stabilizer to facilitate particle size reduction. Factors influencing charge density and stretching state of the cationic polymers influenced the magnitude of the particle. The electrostatic stabilization effect is more prominent than that of the steric stabilizing mechanism. Drug crystalline state was not changed by the addition of cationic polymers. Physical stability of the nanocrystals with cationic polymers was remarkably improved. The in vivo antifungal efficacy of the nanocrystals was dependent on physicochemical properties and pH. FROM THE CLINICAL EDITOR: Cationic polymer stabilizers were used to modify the surface of nanocrystals and the resulting stabilizing mechanisms were compared. The electrostatic stabilization effect was found to be stronger than the steric one. Crystallinity of itraconazole was unchanged by the addition of cationic polymers, while drug physical stability remarkably improved.

Sun W; Tian W; Zhang Y; He J; Mao S; Fang L

2012-05-01

66

PROTON-CONDUCTING COMPOUND AND PROTON-CONDUCTING POLYMER  

UK PubMed Central (United Kingdom)

Provided is a proton-conducting compound which provides proton conductivity without humidification and is suitable for electrochemical device materials such as solid electrolytes for fuel cells and electrolytes for batteries. Provided also is a proton-conducting polymer. The proton-conducting compound is composed of a melamine compound salt obtained from a melamine compound represented by the following formula (1) and a Bronsted acid and the proton-conducting polymer is obtained by homopolymerizing or copolymerizing the melamine compound salt. In formula (1), R1, R2, R3, R4, and R5 each is independently an alkyl group, an aryl group, an alkenyl group, a heterocyclic group, or a hydrogen atom at least one of them is a group other than hydrogen R2 and R3 or R4 and R5 may join together to form a heterocyclic structure and the alkyl group, the aryl group, the alkenyl group, or the heterocyclic group may have a substituent. A melamine compound salt wherein R1 is CH2-CR6-CO-O(CH2)n- polymerizes to yield a proton-conducting polymer. In this particular R1 group, R6 is hydrogen or an alkyl group and n is an integer equal to or larger than 1.

KAWADA ATSUSHI; TASHIRO AYA

67

Conductive polymer/high-{Tc} superconductor assemblies  

Energy Technology Data Exchange (ETDEWEB)

The fabrication of electronic devices from conductive polymer materials has attracted much attention recently. Schottky diodes, molecular transistors, metal-insulator-semiconductor diodes, MIS field effect transistors and light emitting diodies have all been prepared utilizing such substances. With the recent discovery of high temperature superconductivity, new opportunities now exist for the study of molecule/superconductor interactions as well as for the construction of novel hybrid molecule/superconductor devices. The preparation of a hybrid conducting polymer/high-temperature superconductor device consisting of a polypyrrole coated YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} microbridge is reported. Electrochemical techniques are exploited to alter the oxidation state of the polymer and, in doing so, it is found for the first time that superconductivity can be modulated in a controllable and reproducible fashion by a polymer layer. Whereas the neutral (insulating) polypyrrole only slightly influences the electrical properties of the underlying YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} film, the oxidized (conductive) polymer depresses {Tc} by up to 15 K. Thus, a new type of molecular switch for controlling superconductivity is demonstrated.

McDevitt, J.T.; Haupt, S.G.; Riley, D.R.; Zhao, J.; Jones, C. [Univ. of Texas, Austin, TX (United States)

1993-12-31

68

Conductive polymer/high-Tc superconductor assemblies  

International Nuclear Information System (INIS)

[en] The fabrication of electronic devices from conductive polymer materials has attracted much attention recently. Schottky diodes, molecular transistors, metal-insulator-semiconductor diodes, MIS field effect transistors and light emitting diodies have all been prepared utilizing such substances. With the recent discovery of high temperature superconductivity, new opportunities now exist for the study of molecule/superconductor interactions as well as for the construction of novel hybrid molecule/superconductor devices. The preparation of a hybrid conducting polymer/high-temperature superconductor device consisting of a polypyrrole coated YBa2Cu3O7-? microbridge is reported. Electrochemical techniques are exploited to alter the oxidation state of the polymer and, in doing so, it is found for the first time that superconductivity can be modulated in a controllable and reproducible fashion by a polymer layer. Whereas the neutral (insulating) polypyrrole only slightly influences the electrical properties of the underlying YBa2Cu3O7-? film, the oxidized (conductive) polymer depresses Tc by up to 15 K. Thus, a new type of molecular switch for controlling superconductivity is demonstrated

1993-04-02

69

Conductive Polymer Functionalization by Click Chemistry  

DEFF Research Database (Denmark)

Click chemistry is used to obtain new conductive polymer films based on poly(3,4-ethylenedioxythiophene) (PEDOT) from a new azide functional monomer. Postpolymerization, 1,3-dipolar cycloadditions in DMF, using a catalyst system of CUS04 and sodium ascorbate, and different alkynes are performed to functionalize films of PEDOT-N3 and copolymers prepared from EDOT-N3 and 3,4-ethylenedioxythiophene (EDOT). This approach enables new functionalities on PEDOT that could otherwise not withstand the polymerization conditions. Reactions on the thin polymer films have been optimized using an alkynated fluorophore, with reaction times of '"'-'20 h. The applicability of the method is illustrated by coupling of two other alkynes: a short chain fluorocarbon and a MPEG 5000 to the conductive polymer; this alters the advancing water contact angle of the surface by +20° and -20°/-25°, respectively. The targeted chemical surface modifications have been verified by X-ray photoelectron spectroscopy analysis.

Daugaard, Anders Egede; Hvilsted, SØren

2008-01-01

70

Conducting polymers as corrosion resistant coatings  

Energy Technology Data Exchange (ETDEWEB)

Although the majority of top coatings used for corrosion protection are electrically insulating, previous workers have proposed using an electrically active barrier for corrosion control. The most effective corrosion resistant undercoatings in use today are based on chromium compounds. Coatings based on other materials will need to replace these coatings by the turn of the century because of environmental and health concerns. For this reason the authors have begun an investigation of the use of conducting polymers as corrosion resistant coatings as an alternative to metal-based coatings. Conducting polymers have long been considered to be unsuitable for commercial processing, hindering their use for practical applications. Research in the field of electrically conducting polymers has recently produced a number of polymers such as polyaniline and its derivatives which are readily soluble in common organic solvents. The authors coating system, consisting of a conducting polyaniline primer layer, topcoated with epoxy or polyurethane, has been evaluated for corrosion resistance on mild steel substrates. In this paper, the authors report the results of laboratory testing under acidic and saline conditions and the results of testing in the severe launch environment at the Beach Testing Facility at Kennedy Space Center. The launch environment consists of exposure to corrosive HCl exhaust fumes and the salt spray from the Atlantic Ocean.

Wrobleski, D.A.; Benicewicz, B.C.

1994-09-01

71

Nanomembranes and Nanofibers from Biodegradable Conducting Polymers  

Directory of Open Access Journals (Sweden)

Full Text Available This review provides a current status report of the field concerning preparation of fibrous mats based on biodegradable (e.g., aliphatic polyesters such as polylactide or polycaprolactone) and conducting polymers (e.g., polyaniline, polypirrole or polythiophenes). These materials have potential biomedical applications (e.g., tissue engineering or drug delivery systems) and can be combined to get free-standing nanomembranes and nanofibers that retain the better properties of their corresponding individual components. Systems based on biodegradable and conducting polymers constitute nowadays one of the most promising solutions to develop advanced materials enable to cover aspects like local stimulation of desired tissue, time controlled drug release and stimulation of either the proliferation or differentiation of various cell types. The first sections of the review are focused on a general overview of conducting and biodegradable polymers most usually employed and the explanation of the most suitable techniques for preparing nanofibers and nanomembranes (i.e., electrospinning and spin coating). Following sections are organized according to the base conducting polymer (e.g., Sections 4–6 describe hybrid systems having aniline, pyrrole and thiophene units, respectively). Each one of these sections includes specific subsections dealing with applications in a nanofiber or nanomembrane form. Finally, miscellaneous systems and concluding remarks are given in the two last sections.

Elena Llorens; Elaine Armelin; María del Mar Pérez-Madrigal; Luís Javier del Valle; Carlos Alemán; Jordi Puiggalí

2013-01-01

72

Intrinsically conductive polymer thin film piezoresistors  

DEFF Research Database (Denmark)

We report on the piezoresistive effect in the intrinsically conductive polymer, polyaniline. A process recipe for indirect patterning of thin film polyaniline has been developed. Using a specially designed chip, the polyaniline thin films have been characterised with respect to resistivity and strain sensitivity using two- and four-point measurement method. We have found that polyaniline has a negative gauge factor of K = -4.9, which makes it a candidate for piezoresistive read-out in polymer based MEMS-devices. (C) 2007 Elsevier B.V. All rights reserved.

Lillemose, Michael; Spieser, Martin

2008-01-01

73

Charge transport in mesoscopic conducting polymer wires.  

UK PubMed Central (United Kingdom)

In an attempt to reconcile transport in aniline oligomers with that observed in bulk polyaniline, we constructed meso-scale (60 nm) molecular junctions bridged by polyanion-stabilized polyaniline (PANI) strands. Junctions were characterized by their conductance versus electrochemical potential (G-E) and current versus voltage (I-V) characteristics, In contrast to bulk polyaniline, sharp peaks were seen in the G-E data, and these gave rise to negative differential resistance in the I-V curves, behavior much like that observed in aniline oligomers. The width of the conductance peaks increased with the amount of polymer deposited in the junction. In contrast to oligomers, the peaks in the meso-scale devices displayed a large hysteresis. The absolute conductance of the junctions is far too high to be consistent with transport along isolated chains, suggesting that a fundamental charge carrying unit is something morphologically more complex than a single polymer molecule.

He J; Forzani ES; Nagahara LA; Tao N; Lindsay S

2008-09-01

74

Photon-induced formation of CdS nanocrystals in selected areas of polymer matrices  

International Nuclear Information System (INIS)

[en] We demonstrate light-induced formation of semiconductor quantum dots in TOPAS registered polymer matrix with very high control of their size and their spatial localization. Irradiation with UV laser pulses of polymer films embedding Cd thiolate precursors results in the formation of cadmium sulfide nanocrystals well confined in the irradiation area, through a macroscopically nondestructive procedure for the host matrix. With increasing number of laser pulses, we accomplish the formation of nanoparticles with gradually increasing dimensions, resulting in the dynamic change of the spectra emitted by the formed nanocomposite areas. The findings are supported by x-ray diffraction and transmission electron microscopy measurements

2007-10-08

75

Effects of compatability on the conductivity of conducting polymer blends  

Energy Technology Data Exchange (ETDEWEB)

The electrical conductivity of chemically synthesized polyaniline (PANI) blends with nylon 6,6 and polystyrene was measured. The conductivities of the top and bottom of the films cast from blend solutions were found to differ. This effect was most pronounced at low percent loadings of PANI. The maximum difference in conductivity between two sides of the same film was found to be five orders of magnitude in the case of a 5% PANI blend with polystyrene. In this case the conductive polymer appears to be rich on one side of the film rather than more homogeneously dispersed on both sides. SEM provides evidence for the formation of a percolation cluster on one side of the film which is most notable in polystyrene blends. X-ray and FTIR indicated that greater interaction between PANI and nylon 6,6 than PANI and polystyrene. It is proposed that the magnitude of the variation in conductivity between the two sides of the film depends on the compatibility of the conducting and insulating host polymers.

Liu, Mingjun; Nowak, C.K.; Gregory, R.V. [Clemson Univ., SC (United States)

1995-12-01

76

Potential profile in a conducting polymer strip  

DEFF Research Database (Denmark)

Many conjugated polymers show an appreciable difference in volume between their oxidized and reduced forms. This property can be utilized in soft electrochemically driven actuators, "artificial muscles". Several geometries have been proposed for the conversion of the volume expansion into useful mechanical work. In a particularly simple geometry, the length change of polymer strips is exploited. The polymer strips are connected to the driving circuit at the end of the strip that is attached to the support of the device. The other end of the strip is connected to the load. The advantage of this set-up is simplicity and that the maximum force generated in the polymer can be transferred directly to the load. There is, however, an inherent problem in this design that will be examined in this paper. If the potential of the reduced state is below that for oxygen reduction, only a finite length of the free-standing film will be fully reduced. This is due to the reduction of oxygen at the surface of the polymer competing with the reduction of the polymer. For a long strip, the potential will therefore approach the reduction potential of oxygen. This will lower the efficiency of the artificial muscles and complicate measurements on free-standing films. A model of the potential profile in a free-standing strip is derived. It is found that the active length (the length with a given potential change) of the polymer will scale as square root (d sigma /i/sub d/). (d is the thickness, sigma the conductivity of the film, and i/sub d/ the diffusion limited current density for oxygen reduction). The active length is typically of the order of millimeters. The model is compared with measurements on a strip of polypyrrole doped with dodecylbenzene sulfonate

Bay, Lasse; West, Keld

2002-01-01

77

Gas Sensors Based on Conducting Polymers  

Directory of Open Access Journals (Sweden)

Full Text Available The gas sensors fabricated by using conducting polymers such as polyaniline (PAni), polypyrrole (PPy) and poly (3,4-ethylenedioxythiophene) (PEDOT) as the active layers have been reviewed. This review discusses the sensing mechanism and configurations of the sensors. The factors that affect the performances of the gas sensors are also addressed. The disadvantages of the sensors and a brief prospect in this research field are discussed at the end of the review.

Hua Bai; Gaoquan Shi

2007-01-01

78

Conducting polymer coated neural recording electrodes  

Science.gov (United States)

Objective. Neural recording electrodes suffer from poor signal to noise ratio, charge density, biostability and biocompatibility. This paper investigates the ability of conducting polymer coated electrodes to record acute neural response in a systematic manner, allowing in depth comparison of electrochemical and electrophysiological response. Approach. Polypyrrole (Ppy) and poly-3,4-ethylenedioxythiophene (PEDOT) doped with sulphate (SO4) or para-toluene sulfonate (pTS) were used to coat iridium neural recording electrodes. Detailed electrochemical and electrophysiological investigations were undertaken to compare the effect of these materials on acute in vivo recording. Main results. A range of charge density and impedance responses were seen with each respectively doped conducting polymer. All coatings produced greater charge density than uncoated electrodes, while PEDOT-pTS, PEDOT-SO4 and Ppy-SO4 possessed lower impedance values at 1 kHz than uncoated electrodes. Charge density increased with PEDOT-pTS thickness and impedance at 1 kHz was reduced with deposition times up to 45 s. Stable electrochemical response after acute implantation inferred biostability of PEDOT-pTS coated electrodes while other electrode materials had variable impedance and/or charge density after implantation indicative of a protein fouling layer forming on the electrode surface. Recording of neural response to white noise bursts after implantation of conducting polymer-coated electrodes into a rat model inferior colliculus showed a general decrease in background noise and increase in signal to noise ratio and spike count with reduced impedance at 1 kHz, regardless of the specific electrode coating, compared to uncoated electrodes. A 45 s PEDOT-pTS deposition time yielded the highest signal to noise ratio and spike count. Significance. A method for comparing recording electrode materials has been demonstrated with doped conducting polymers. PEDOT-pTS showed remarkable low fouling during acute implantation, inferring good biostability. Electrode impedance at 1 kHz was correlated with background noise and inversely correlated with signal to noise ratio and spike count, regardless of coating. These results collectively confirm a potential for improvement of neural electrode systems by coating with conducting polymers.

Harris, Alexander R.; Morgan, Simeon J.; Chen, Jun; Kapsa, Robert M. I.; Wallace, Gordon G.; Paolini, Antonio G.

2013-02-01

79

Conducting polymer coated neural recording electrodes.  

UK PubMed Central (United Kingdom)

OBJECTIVE: Neural recording electrodes suffer from poor signal to noise ratio, charge density, biostability and biocompatibility. This paper investigates the ability of conducting polymer coated electrodes to record acute neural response in a systematic manner, allowing in depth comparison of electrochemical and electrophysiological response. APPROACH: Polypyrrole (Ppy) and poly-3,4-ethylenedioxythiophene (PEDOT) doped with sulphate (SO4) or para-toluene sulfonate (pTS) were used to coat iridium neural recording electrodes. Detailed electrochemical and electrophysiological investigations were undertaken to compare the effect of these materials on acute in vivo recording. MAIN RESULTS: A range of charge density and impedance responses were seen with each respectively doped conducting polymer. All coatings produced greater charge density than uncoated electrodes, while PEDOT-pTS, PEDOT-SO4 and Ppy-SO4 possessed lower impedance values at 1 kHz than uncoated electrodes. Charge density increased with PEDOT-pTS thickness and impedance at 1 kHz was reduced with deposition times up to 45 s. Stable electrochemical response after acute implantation inferred biostability of PEDOT-pTS coated electrodes while other electrode materials had variable impedance and/or charge density after implantation indicative of a protein fouling layer forming on the electrode surface. Recording of neural response to white noise bursts after implantation of conducting polymer-coated electrodes into a rat model inferior colliculus showed a general decrease in background noise and increase in signal to noise ratio and spike count with reduced impedance at 1 kHz, regardless of the specific electrode coating, compared to uncoated electrodes. A 45 s PEDOT-pTS deposition time yielded the highest signal to noise ratio and spike count. SIGNIFICANCE: A method for comparing recording electrode materials has been demonstrated with doped conducting polymers. PEDOT-pTS showed remarkable low fouling during acute implantation, inferring good biostability. Electrode impedance at 1 kHz was correlated with background noise and inversely correlated with signal to noise ratio and spike count, regardless of coating. These results collectively confirm a potential for improvement of neural electrode systems by coating with conducting polymers.

Harris AR; Morgan SJ; Chen J; Kapsa RM; Wallace GG; Paolini AG

2013-02-01

80

Electrochemical Analysis of Conducting Polymer Thin Films  

Directory of Open Access Journals (Sweden)

Full Text Available Polyelectrolyte multilayers built via the layer-by-layer (LbL) method has been one of the most promising systems in the field of materials science. Layered structures can be constructed by the adsorption of various polyelectrolyte species onto the surface of a solid or liquid material by means of electrostatic interaction. The thickness of the adsorbed layers can be tuned precisely in the nanometer range. Stable, semiconducting thin films are interesting research subjects. We use a conducting polymer, poly(p-phenylene vinylene) (PPV), in the preparation of a stable thin film via the LbL method. Cyclic voltammetry and electrochemical impedance spectroscopy have been used to characterize the ionic conductivity of the PPV multilayer films. The ionic conductivity of the films has been found to be dependent on the polymerization temperature. The film conductivity can be fitted to a modified Randle’s circuit. The circuit equivalent calculations are performed to provide the diffusion coefficient values.

Ritesh N. Vyas; Bin Wang

2010-01-01

 
 
 
 
81

Patterned structures of in situ size controlled CdS nanocrystals in a polymer matrix under UV irradiation  

International Nuclear Information System (INIS)

[en] A method of in situ formation of patterns of size controlled CdS nanocrystals in a polymer matrix by pulsed UV irradiation is presented. The films consist of Cd thiolate precursors with different carbon chain lengths embedded in TOPAS polymer matrices. Under UV irradiation the precursors are photolyzed, driving to the formation of CdS nanocrystals in the quantum size regime, with size and concentration defined by the number of incident UV pulses, while the host polymer remains macroscopically/microscopically unaffected. The emission of the formed nanocomposite materials strongly depends on the dimensions of the CdS nanocrystals, thus, their growth at the different phases of the irradiation is monitored using spatially resolved photoluminescence by means of a confocal microscope. X-ray diffraction measurements verified the existence of the CdS nanocrystals, and defined their crystal structure for all the studied cases. The results are reinforced by transmission electron microscopy. It is proved that the selection of the precursor determines the efficiency of the procedure, and the quality of the formed nanocrystals. Moreover it is demonstrated that there is the possibility of laser induced formation of well-defined patterns of CdS nanocrystals, opening up new perspectives in the development of nanodevices.

2009-04-15

82

Patterned structures of in situ size controlled CdS nanocrystals in a polymer matrix under UV irradiation  

Energy Technology Data Exchange (ETDEWEB)

A method of in situ formation of patterns of size controlled CdS nanocrystals in a polymer matrix by pulsed UV irradiation is presented. The films consist of Cd thiolate precursors with different carbon chain lengths embedded in TOPAS polymer matrices. Under UV irradiation the precursors are photolyzed, driving to the formation of CdS nanocrystals in the quantum size regime, with size and concentration defined by the number of incident UV pulses, while the host polymer remains macroscopically/microscopically unaffected. The emission of the formed nanocomposite materials strongly depends on the dimensions of the CdS nanocrystals, thus, their growth at the different phases of the irradiation is monitored using spatially resolved photoluminescence by means of a confocal microscope. X-ray diffraction measurements verified the existence of the CdS nanocrystals, and defined their crystal structure for all the studied cases. The results are reinforced by transmission electron microscopy. It is proved that the selection of the precursor determines the efficiency of the procedure, and the quality of the formed nanocrystals. Moreover it is demonstrated that there is the possibility of laser induced formation of well-defined patterns of CdS nanocrystals, opening up new perspectives in the development of nanodevices.

Fragouli, D; Pompa, P P; Caputo, G; Cingolani, R; Athanassiou, A [NNL-National Nanotechnology Laboratory, INFM, CNR, Via Arnesano, 73100 Lecce (Italy); Resta, V; Laera, A M; Tapfer, L [ENEA, Centro Ricerche Brindisi, SS7 Appia Km 706, I-72100 Brindisi (Italy)], E-mail: despina.fragouli@unile.it

2009-04-15

83

Polymer-Grafted Cellulose Nanocrystals as pH-Responsive Reversible Flocculants.  

UK PubMed Central (United Kingdom)

Cellulose nanocrystals (CNCs) are a sustainable nanomaterial with applications spanning composites, coatings, gels, and foams. Surface modification routes to optimize CNC interfacial compatibility and functionality are required to exploit the full potential of this material in the design of new products. In this work, CNCs have been rendered pH-responsive by surface-initiated graft polymerization of 4-vinylpyridine with the initiator ceric(IV) ammonium nitrate. The polymerization is a one-pot, water-based synthesis carried out under sonication, which ensures even dispersion of the cellulose nanocrystals during the reaction. The resultant suspensions of poly(4-vinylpyridine)-grafted cellulose nanocrystals (P4VP-g-CNCs) show reversible flocculation and sedimentation with changes in pH; the loss of colloidal stability is visible by eye even at concentrations as low as 0.004 wt %. The presence of grafted polymer and the ability to tune the hydrophilic/hydrophobic properties of P4VP-g-CNCs were characterized by Fourier transform infrared spectroscopy, elemental analysis, electrophoretic mobility, mass spectrometry, transmittance spectroscopy, contact-angle measurements, thermal analysis, and various microscopies. Atomic force microscopy showed no observable changes in the CNC dimensions or degree of aggregation after polymer grafting, and a liquid crystalline nematic phase of the modified CNCs was detected by polarized light microscopy. Controlled stability and wettability of P4VP-g-CNCs is advantageous both in composite design, where cellulose nanocrystals generally have limited dispersibility in nonpolar matrices, and as biodegradable flocculants. The responsive nature of these novel nanoparticles may offer new applications for CNCs in biomedical devices, as clarifying agents, and in industrial separation processes.

Kan KH; Li J; Wijesekera K; Cranston ED

2013-09-01

84

Polymer-Grafted Cellulose Nanocrystals as pH-Responsive Reversible Flocculants.  

Science.gov (United States)

Cellulose nanocrystals (CNCs) are a sustainable nanomaterial with applications spanning composites, coatings, gels, and foams. Surface modification routes to optimize CNC interfacial compatibility and functionality are required to exploit the full potential of this material in the design of new products. In this work, CNCs have been rendered pH-responsive by surface-initiated graft polymerization of 4-vinylpyridine with the initiator ceric(IV) ammonium nitrate. The polymerization is a one-pot, water-based synthesis carried out under sonication, which ensures even dispersion of the cellulose nanocrystals during the reaction. The resultant suspensions of poly(4-vinylpyridine)-grafted cellulose nanocrystals (P4VP-g-CNCs) show reversible flocculation and sedimentation with changes in pH; the loss of colloidal stability is visible by eye even at concentrations as low as 0.004 wt %. The presence of grafted polymer and the ability to tune the hydrophilic/hydrophobic properties of P4VP-g-CNCs were characterized by Fourier transform infrared spectroscopy, elemental analysis, electrophoretic mobility, mass spectrometry, transmittance spectroscopy, contact-angle measurements, thermal analysis, and various microscopies. Atomic force microscopy showed no observable changes in the CNC dimensions or degree of aggregation after polymer grafting, and a liquid crystalline nematic phase of the modified CNCs was detected by polarized light microscopy. Controlled stability and wettability of P4VP-g-CNCs is advantageous both in composite design, where cellulose nanocrystals generally have limited dispersibility in nonpolar matrices, and as biodegradable flocculants. The responsive nature of these novel nanoparticles may offer new applications for CNCs in biomedical devices, as clarifying agents, and in industrial separation processes. PMID:23865631

Kan, Kevin H M; Li, Jian; Wijesekera, Kushlani; Cranston, Emily D

2013-08-02

85

Conducting polymer-hydrogels for medical electrode applications  

Directory of Open Access Journals (Sweden)

Full Text Available Conducting polymers hold significant promise as electrode coatings; however, they are characterized by inherently poor mechanical properties. Blending or producing layered conducting polymers with other polymer forms, such as hydrogels, has been proposed as an approach to improving these properties. There are many challenges to producing hybrid polymers incorporating conducting polymers and hydrogels, including the fabrication of structures based on two such dissimilar materials and evaluation of the properties of the resulting structures. Although both fabrication and evaluation of structure–property relationships remain challenges, materials comprised of conducting polymers and hydrogels are promising for the next generation of bioactive electrode coatings.

Rylie A Green, Sungchul Baek, Laura A Poole-Warren and Penny J Martens

2010-01-01

86

Biomimetic electrochemistry from conducting polymers. A review  

International Nuclear Information System (INIS)

[en] Highlights: ? Composition and properties of conducting polymers change during reactions. ? These properties are being exploited to develop biomimetic reactive and soft devices. ? The state of the art for artificial muscles sensing working conditions was reviewed. ? Smart membranes, drug delivery devices and nervous interfaces were also reviewed. - Abstract: Films of conducting polymers in the presence of electrolytes can be oxidized or reduced by the flow of anodic or cathodic currents. Ions and solvent are exchanged during a reaction for charge and osmotic pressure balance. A reactive conducting polymer contains ions and solvent. Such variation of composition during a reaction is reminiscent of the biological processes in cells. Along changes to the composition of the material during a reaction, there are also changes to other properties, including: volume (electrochemomechanical), colour (electrochromic), stored charge (electrical storage), porosity or permselectivity (electroporosity), stored chemicals, wettability and so on. Most of those properties mimic similar property changes in organs during their functioning. These properties are being exploited to develop biomimetic reactive and soft devices: artificial muscles and polymeric actuators; supercapacitors and all organic batteries; smart membranes; electron-ion transducers; nervous interfaces and artificial synapses, or drug delivery devices. In this review we focus on the state of the art for artificial muscles, smart membranes and electron-ion transducers. The reactive nature of those devices provide them with a unique advantage related to the present days technologies: any changes in the surrounding physical or chemical variable acting on the electrochemical reaction rate will be sensed by the device while working. Working under constant current (driving signal), the evolution of the device potential or the evolution of the consumed electrical energy (sensing signals) senses and quantifies the variable increment. Driving and sensing signals are present, simultaneously, in the same two connecting wires. It is possible to prepare electrochemical devices based on conducting polymers in which there are several kinds of different sensors and one actuator embedded in one device. Examples of the tools and products, start-up companies, increasing evolution of scientific literature and patents are also presented. Scientific and technological challenges are also considered.

2012-12-01

87

Conducting polymers in biosensors: A review  

Directory of Open Access Journals (Sweden)

Full Text Available Biosensors have gained immense acceptance in the field of medical diagnostics, food safety, environment control and biodefence application due to high sensitivity, specificity, ability for real-time analysis coupled with speed and low cost. Application of conducting polymers (CPs) in biosensors has recently aroused much interest. CPs provide an excellent opportunity for high selective, specific, stable, economic and handy biosensing devices. This paper first introduced different types of CPs, their unique properties and their synthesis, then specific information is provided on their modification for use in biosensors applications

Alina-Mihaela Ni??

2010-01-01

88

A sepiolite modified conducting polymer based biosensor.  

UK PubMed Central (United Kingdom)

A conducting polymer modified with sepiolite was utilized in the construction of a highly sensitive and fast amperometric cholesterol biosensor. In this study a monomer; (10,13-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)dibenzo[a,c]phenazine (PHED)) was synthesized and then its polymer was coated on a graphite electrode by electropolymerization to obtain a matrix for enzyme immobilization. Cholesterol oxidase was immobilized onto polymer coated electrode by adsorption technique. Sepiolite was introduced for a successful immobilization of the cholesterol oxidase. Immobilized enzyme kinetic parameters (KM(app), Imax) were evaluated by Michaelis-Menten kinetics and calculated as 0.031mM and 6.06?A, respectively. LOD and sensitivity were estimated as 0.36?M and 1.64mA/mMcm(2). Characterization of designed biosensor was done to examine the effect of various factors such as enzyme amount, optimum pH and shelf-life. A novel accurate and inexpensive cholesterol biosensor was developed for the determination of total cholesterol in food samples.

Soylemez S; Kanik FE; Tarkuc S; Udum YA; Toppare L

2013-07-01

89

Preparation and characterization of poled nanocrystal and polymer composite PZT/PC films  

International Nuclear Information System (INIS)

Pb(Zr0.52Ti0.48)O3 (PZT) nanocrystals and transparent polycarbonate (PC) composite thin films with useful properties for ferroelectric, piezoelectric and electro-optic devices were prepared by a spin-coating technique. Ultra-fine PZT (?40-50 nm) nanocrystals with pure perovskite tetragonal phase were synthesized by a hydrothermal method. The structure and morphology of the composite thin films were studied by means of X-ray diffraction and scanning electron microscopy. To obtain the optimum electro-optic properties of poled composite films, the poling condition under an external electric field was optimized through the dielectric properties of PZT and PC polymer and effective field intensity theory. The electro-optic coefficient of the poled PZT/PC composite film is estimated to be 30.5 pm/V. The transparency spectra were measured and the optical band gaps of the unpoled, poled at 145 C and poled at 165 C composite thin films are estimated to be 4.26 eV, 4.21 eV and 4.18 eV, respectively. The measured dielectric constants of PZT/PC are in good agreement with the calculated values for the composite with a very small PZT volume fraction, based on the Onsager effective-field theory. This offers a reliable and indirect way to predict the dielectric constant of nanocrystals. (orig.)

2005-01-01

90

Conducting polymer nanocomposites: interactions at interfaces  

Science.gov (United States)

We report that dispersions and functionalizations of single-walled carbon nanotubes (SWNTs) with different dispersing methods and dispersing agents result in SWNTs with different electronic structures and surface chemistries. By In-situ polymerizing conducting polymer (here, polyaniline boronic acid (PABA)) in the presence of these SWNTs, we obtained composites with different chemical structures of PABA, different arrangement and distribution of the SWNTs, and dramatically different conductive properties. We also found the polymerization rates are very different depending on the electronic fingerprint and surface chemistry of the carbon nanotubes. We applied a series of techniques to characterize the produced composites and studying the electronic and molecular interactions in the composites to understand these remarkable effects.

Chiu, Pui Lam; Ma, Yufeng; Serrano, Arnaldo; Wang, Lin; Mendelsohn, Richard; He, Huixin

2007-10-01

91

Nanocomposites based on highly luminescent nanocrystals and semiconducting conjugated polymer for inkjet printing.  

UK PubMed Central (United Kingdom)

In this work nanocomposites based on organic-capped semiconductor nanocrystals formed of a core of CdSe coated with a shell of ZnS (CdSe@ZnS), with different sizes, and a semiconducting conjugated polymer, namely poly[(9,9-dihexylfluoren-2,7-diyl)-alt- (2,5-dimethyl-1,4-phenylene)] (PF-DMB) have been investigated. The nanocomposites are prepared by mixing the pre-synthesized components in organic solvents, thereby assisting the dispersion of the organic-coated nano-objects in the polymer host. UV-vis steady state and time-resolved spectroscopy along with (photo)electrochemical techniques have been performed to characterize the obtained materials. The study shows that the embedded nanocrystals increase the PF-DMB stability against oxidation and, at the same time, extend the light harvesting capability to the visible spectral region, thus resulting in detectable photocurrent signals. The nanocomposites have been dispensed by means of a piezo-actuated inkjet system. Such inks present viscosity and surface tension properties well suited for stable and reliable drop-on-demand printing using an inkjet printer. The fabrication of arrays of single-color pixels made of the nanocomposites and micrometers in size has been performed. Confocal and atomic force microscopy have confirmed that inkjet-printed microstructures present the intrinsic emission properties of both the embedded nanocrystals and PF-DMB, resulting in a combined luminescence. Finally, the morphology of the printed pixels is influenced by the embedded nanofillers.

Binetti E; Ingrosso C; Striccoli M; Cosma P; Agostiano A; Pataky K; Brugger J; Curri ML

2012-02-01

92

Conducting Polymer Nanostructures: Template Synthesis and Applications in Energy Storage  

Directory of Open Access Journals (Sweden)

Full Text Available Conducting polymer nanostructures have received increasing attention in both fundamental research and various application fields in recent decades. Compared with bulk conducting polymers, conducting polymer nanostructures are expected to display improved performance in energy storage because of the unique properties arising from their nanoscaled size: high electrical conductivity, large surface area, short path lengths for the transport of ions, and high electrochemical activity. Template methods are emerging for a sort of facile, efficient, and highly controllable synthesis of conducting polymer nanostructures. This paper reviews template synthesis routes for conducting polymer nanostructures, including soft and hard template methods, as well as its mechanisms. The application of conducting polymer mesostructures in energy storage devices, such as supercapacitors and rechargeable batteries, are discussed.

Lijia Pan; Hao Qiu; Chunmeng Dou; Yun Li; Lin Pu; Jianbin Xu; Yi Shi

2010-01-01

93

Enhancing the efficiency of solution-processed polymer:colloidal nanocrystal hybrid photovoltaic cells using ethanedithiol treatment.  

Science.gov (United States)

Advances in colloidal inorganic nanocrystal synthesis and processing have led to the demonstration of organic-inorganic hybrid photovoltaic (PV) cells using low-cost solution processes from blends of conjugated polymer and colloidal nanocrystals. However, the performance of such hybrid PV cells has been limited due to the lack of control at the complex interfaces between the organic and inorganic hybrid active materials. Here we show that the efficiency of hybrid PV devices can be significantly enhanced by engineering the polymer-nanocrystal interface with proper chemical treatment. Using two different conjugated polymers, poly(3-hexylthiophene) (P3HT) and poly[2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b']-dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT), we show that treating the polymer:nanocrystal hybrid film in an ethanedithiol-containing acetonitrile solution can increase the efficiency of the hybrid PV devices by 30-90%, and a maximum power conversion efficiency of 5.2 ± 0.3% was obtained in the PCPDTBT:CdSe devices at 0.2 sun (AM 1.5G), which was slightly reduced to 4.7 ± 0.3% at 1 sun. The ethanedithiol treatment did not result in significant changes in the morphology and UV-vis optical absorption of the hybrid thin films; however, infrared absorption, NMR, and X-ray photoelectron spectroscopies revealed the effective removal of organic ligands, especially the charged phosphonic acid ligands, from the CdSe nanorod surface after the treatment, accompanied by the possible monolayer passivation of nanorod surfaces with Cd-thiolates. We attribute the hybrid PV cell efficiency increase upon the ethanedithiol treatment to the reduction in charge and exciton recombination sites on the nanocrystal surface and the simultaneous increase in electron transport through the hybrid film. PMID:23668301

Zhou, Renjia; Stalder, Romain; Xie, Dongping; Cao, Weiran; Zheng, Ying; Yang, Yixing; Plaisant, Marc; Holloway, Paul H; Schanze, Kirk S; Reynolds, John R; Xue, Jiangeng

2013-05-22

94

Modified conductivity of polymer materials with proton beam  

Energy Technology Data Exchange (ETDEWEB)

Ionic conductivity of polymer materials is of increasing interest in many scientific fields. Industrial applications seem to be promising. In the present investigation, we used proton bombardment to modify the characteristic properties of polymers, especially for improvement in conductivity and hardening gel polymers. Particle beam bombardment is known to produce many scissions by particle passages and new bonds by bridge connection. These effects may modify various properties in many ways. We examined the modification of conductivity in solid polymers composed of polyethylene oxide and polyurethane and the surface appearance of gel polymers with bombardment by a proton beam using the accelerator facility of Tsukuba University. The results indicated proton bombardment induced conductivity changes in various ways according to particle range and polymer properties. (author)

Matsumoto, Shinji [Taiyo Material Co., Tokyo (Japan); Seki, Miharu [Natural Sciences, Chiba Inst. of Tech., Narashino, Chiba (Japan); Shima, Kunihiro; Ishihara, Toyoyuki [Tsukuba Univ., Tandem Accelerator, Tsukuba, Ibaraki (Japan)

2001-03-01

95

Modified conductivity of polymer materials with proton beam  

International Nuclear Information System (INIS)

[en] Ionic conductivity of polymer materials is of increasing interest in many scientific fields. Industrial applications seem to be promising. In the present investigation, we used proton bombardment to modify the characteristic properties of polymers, especially for improvement in conductivity and hardening gel polymers. Particle beam bombardment is known to produce many scissions by particle passages and new bonds by bridge connection. These effects may modify various properties in many ways. We examined the modification of conductivity in solid polymers composed of polyethylene oxide and polyurethane and the surface appearance of gel polymers with bombardment by a proton beam using the accelerator facility of Tsukuba University. The results indicated proton bombardment induced conductivity changes in various ways according to particle range and polymer properties. (author)

2001-01-01

96

In situ growth of well-dispersed CdS nanocrystals in semiconducting polymers.  

UK PubMed Central (United Kingdom)

A straight synthetic route to fabricate hybrid nanocomposite films of well-dispersed CdS nanocrystals (NCs) in poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) is reported. A soluble cadmium complex [Cd(SBz)2]2.MI, obtained by incorporating a Lewis base (1-methylimidazole, MI) on the cadmium bis(benzyl)thiol, is used as starting reagent in an in situ thermolytic process. CdS NCs with spherical shape nucleate and grow well below 200[degree sign]C in a relatively short time (30 min). Photoluminescence spectroscopy measurements performed on CdS/MEH-PPV nanocomposites show that CdS photoluminescence peaks are totally quenched inside MEH-PPV, if compared to CdS/PMMA nanocomposites, as expected due to overlapping of the polymer absorption and CdS emission spectra. The CdS NCs are well-dispersed in size and homogeneously distributed within MEH-PPV matrix as proved by transmission electron microscopy. Nanocomposites with different precursor/polymer weight ratios were prepared in the range from 1:4 to 4:1. Highly dense materials, without NCs clustering, were obtained for a weight/weight ratio of 2:3 between precursor and polymer, making these nanocomposites particularly suitable for optoelectronic and solar energy conversion applications.

Laera AM; Resta V; Piscopiello E; Miceli V; Schioppa M; Scalone AG; Di Benedetto F; Tapfer L

2013-09-01

97

Nobel Prize 2000: from conducting polymers to molecular electronics  

International Nuclear Information System (INIS)

In this paper the development of conducting organic polymers is reviewed. Poly(3-alkylthiophenes) with regioregularity exceeding 99% are especially interesting because if used as a thin semiconducting layer in the field effect transistor (FET) configuration they become superconducting at 2.35 K. This is the first example of the superconductivity of an organic polymer. Fields of use of conducting polymers are reviewed, too

2001-01-01

98

Spatially Selective Functionalization of Conducting Polymers by "Electroclick" Chemistry  

DEFF Research Database (Denmark)

Conducting polymer microelectrodes can electrochemically generate the catalyst required for their own functionalization by "click chemistry" with high spatial resolution. Interdigitated microelectrodes prepared from an azide-containing conducting polymer are selectively functionalized in sequence by two alkyne-modified fluorophores by control of the applied potentials.

Hansen, Thomas Steen; Daugaard, Anders Egede

2009-01-01

99

TiO2 nanocrystals shell layer on highly conducting indium tin oxide nanowire for photovoltaic devices.  

UK PubMed Central (United Kingdom)

We demonstrated a highly efficient conducting indium tin oxide (ITO) core-TiO2 nanocrystals shell nanowire array for a photoelectrode in dye-sensitized solar cells with regard to light harvest and charge collection. The TiO2 shell layer, consisting of anatase nanocrystals of ~2 nm, were successfully formed on a single crystalline ITO nanowire prepared via a vapor transport method using repetitive TiCl4 aqueous solution treatments at 50 °C. We found that the nanocrystal size and number of Cl(-) ions remaining on the formed shell layer critically influence the dye loading properties. Moreover, these factors can be controlled by means of a post-annealing process. We also found that the dye loading and the back electron transport from the conductive ITO nanowire to the electrolyte mainly determine the final cell performance. The proposed double-shell layer structure consisting of dense and porous layers showed significantly improved cell performance.

Han HS; Kim JS; Kim DH; Han GS; Jung HS; Noh JH; Hong KS

2013-04-01

100

Synthetic Method for Conducting Polymer Nanofibers.  

Science.gov (United States)

Polymer nanofibers, such as polyaniline nanofibers, with uniform diameters less than 500 nm can be made in bulk quantities through a facile aqueous and organic interfacial polymerization method at ambient conditions. The nanofibers have lengths varying fr...

B. H. Weiller J. Huang R. B. Kaner S. Virji

2003-01-01

 
 
 
 
101

Polyvinyl alcohol as photoluminescent conductive polymer  

Science.gov (United States)

We synthesized a photoluminescent conductor polymer composed of polyvinyl alcohol, which was doped with nickel chloride to decrease its resistivity (300 Ocm) and benzalkonium chloride to obtain photoluminescence properties, when it is radiated with a green laser beam (532 nm). We compared its absorbance curve and its energy emitted curve to observe the amount energy that is taken advantage of this process. Besides we research the photoluminescence behavior when an electric currant is applied in our conductor polymer, obtaining a modulation capacity.

Ruiz-Limón, B.; Wetzel, G. B. J.; Olivares-Pérez, A.; Ponce-Lee, E. L.; Hernández-Garay, M. P.; Páez-Trujillo, G.; Toxqui-López, S.; Fuentes-Tapia, I.

2007-02-01

102

Self-assembled hybrid materials based on conjugated polymers and semiconductors nano-crystals for plastic solar cells  

International Nuclear Information System (INIS)

[en] This work is devoted to the elaboration of self-assembled hybrid materials based on poly(3- hexyl-thiophene) and CdSe nano-crystals for photovoltaic applications. For that, complementary molecular recognition units were introduced as side chain groups on the polymer and at the nano-crystals' surface. Diamino-pyrimidine groups were introduced by post-functionalization of a precursor copolymer, namely poly(3-hexyl-thiophene-co-3- bromo-hexyl-thiophene) whereas thymine groups were introduced at the nano-crystals' surface by a ligand exchange reaction with 1-(6-mercapto-hexyl)thymine. However, due to their different solubility, the mixing of the two components by solution processes is difficult. A 'one-pot' procedure was developed, but this method led to insoluble aggregates without control of the hybrid composition. To overcome the solubility problem, the layer-by-layer method was used to prepare the films. This method allows a precise control of the deposition process. Experimental parameters were tested in order to evaluate their impact on the resulting film. The films morphology was investigated by microscopy and X-Ray diffraction techniques. These analyses reveal an interpenetrated structure of nano-crystals within the polymer matrix rather than a multilayered structure. Electrochemical and spectro electrochemical studies were performed on the hybrid material deposited by the LBL process. Finally the materials were tested in a solar cell configuration and the I=f(V) curves reveals a clear photovoltaic behaviour. (author)

2007-01-01

103

Characterization and Experimental Verification of Solid Polymer Electrolyte for Conductive Polymer Actuator Operated in Air  

Energy Technology Data Exchange (ETDEWEB)

In order to fabricate stable conductive polymer actuators which can be operated in air, conductivity and solidity of polymer electrolyte materials have been studied. It was found that Nafion+LiCl is appropriate material to be used for conductive polymer actuator. Using the Nafion+LiCl solid polymer electrolyte, single layer PPy actuators have been fabricated and their deflection was measured. Double layer PPy actuators make up for shortcoming of single layer PPy actuator and displacement and frequency response can be improved by fabrication of double layer PPy actuator. This kind of all-solid-polymer actuator can be used for practical applications. (author). 7 refs., 21 figs.

Ahn, H.J.; Pak, J.H. [Korea University, Seoul (Korea); Lee, S.K. [Dankook University, Seoul (Korea)

2002-03-01

104

Improved morphology in electrochemically grown conducting polymer films  

Energy Technology Data Exchange (ETDEWEB)

A conducting polymer film with an improved space filling is formed on a metal electrode surface. A self-assembling monolayer is formed directly on the metal surface where the monolayer has a first functional group that binds to the metal surface and a second chemical group that forms a chemical bonding site for molecules forming the conducting polymer. The conducting polymer is then conventionally deposited by electrochemical deposition. In one example, a conducting film of polyaniline is formed on a gold electrode surface with an intermediate monolayer of p-aminothiophenol.

Rubinstein, I.; Gottesfeld, S.; Sabatani, E.

1990-12-31

105

Electrical properties of conductive Ge nanocrystal thin films fabricated by low temperature in situ growth.  

UK PubMed Central (United Kingdom)

Thin films composed of Ge nanocrystals embedded in an amorphous SiO(2) matrix (Ge-NC TFs) were prepared using a low temperature in situ growth method. Unexpected high p-type conductivity was observed in the intrinsic Ge-NC TFs. Unintentional doping from shallow dopants was excluded as a candidate mechanism of hole generation. Instead, the p-type characteristic was attributed to surface state induced hole accumulation in NCs, and the hole conduction was found to be a thermally activated process involving charge hopping from one NC to its nearest neighbor. Theoretical analysis has shown that the density of surface states in Ge-NCs is sufficient to induce adequate holes for measured conductivity. The film conductivity can be improved significantly by post-growth rapid thermal annealing and this effect is explained by a simple thermodynamic model. The impact of impurities on the conduction properties was also studied. Neither compensation nor enhancement in conduction was observed in the Sb- and Ga-doped Ge-NC TFs, respectively. This could be attributed to the fact that these impurities are no longer shallow dopants in NCs and are much less likely to be effectively activated. Finally, the photovoltaic effect of heterojunction diodes employing such Ge-NC TFs was characterized in order to demonstrate its functionality in device implementation.

Zhang B; Yao Y; Patterson R; Shrestha S; Green MA; Conibeer G

2011-03-01

106

Electrical properties of conductive Ge nanocrystal thin films fabricated by low temperature in situ growth.  

Science.gov (United States)

Thin films composed of Ge nanocrystals embedded in an amorphous SiO(2) matrix (Ge-NC TFs) were prepared using a low temperature in situ growth method. Unexpected high p-type conductivity was observed in the intrinsic Ge-NC TFs. Unintentional doping from shallow dopants was excluded as a candidate mechanism of hole generation. Instead, the p-type characteristic was attributed to surface state induced hole accumulation in NCs, and the hole conduction was found to be a thermally activated process involving charge hopping from one NC to its nearest neighbor. Theoretical analysis has shown that the density of surface states in Ge-NCs is sufficient to induce adequate holes for measured conductivity. The film conductivity can be improved significantly by post-growth rapid thermal annealing and this effect is explained by a simple thermodynamic model. The impact of impurities on the conduction properties was also studied. Neither compensation nor enhancement in conduction was observed in the Sb- and Ga-doped Ge-NC TFs, respectively. This could be attributed to the fact that these impurities are no longer shallow dopants in NCs and are much less likely to be effectively activated. Finally, the photovoltaic effect of heterojunction diodes employing such Ge-NC TFs was characterized in order to demonstrate its functionality in device implementation. PMID:21325714

Zhang, B; Yao, Y; Patterson, R; Shrestha, S; Green, M A; Conibeer, G

2011-02-17

107

Conductive polymer coatings for anodes in aqueous electrowinning  

Science.gov (United States)

This article discusses the potential application of electrically conductive polymers as protective coatings for permanent lead anodes employed in aqueous electrowinning processes. Also presented are results from a preliminary study of the performance of two intrinsically conductive polymers (polyaniline and poly 3,4,5-trifluorophenylthiophene [TFPT]) under mild copper electrowinning conditions as conductive and protective coatings on anodic surfaces. The laboratory results indicated that using lead alloy anodes coated with TFPT merits continued research.

Alfantazi, A. M.; Moskalyk, R. R.

2003-07-01

108

White light generation tuned by dual hybridization of nanocrystals and conjugated polymers  

International Nuclear Information System (INIS)

Dual hybridization of highly fluorescent conjugated polymers and highly luminescent nanocrystals (NCs) is developed and demonstrated in multiple combinations for controlled white light generation with high color rendering index (CRI) (> 80) for the first time. The generated white light is tuned using layer-by-layer assembly of CdSe/ZnS core-shell NCs closely packed on polyfluorene, hybridized on near-UV emitting nitride-based light emitting diodes (LEDs). The design, synthesis, growth, fabrication and characterization of these hybrid inorganic-organic white LEDs are presented. The following experimental realizations are reported: (i) layer-by-layer hybridization of yellow NCs (?PL=580 nm) and blue polyfluorene (?PL=439 nm) with tristimulus coordinates of (x, y)=(0.31, 0.27), correlated color temperature of Tc=6962 K and CRI of Ra=53.4; (ii) layer-by-layer assembly of yellow and green NCs (?PL=580 and 540 nm) and blue polyfluorene (?PL=439 nm) with (x, y)=(0.23, 0.30), Tc=14395 K and Ra=65.7; and (iii) layer-by-layer deposition of yellow, green and red NCs (?PL=580, 540 and 620 nm) and blue polyfluorene (?PL=439 nm) with (x, y)=(0.38, 0.39), Tc=4052 K and Ra= 83.0. The CRI is demonstrated to be well controlled and significantly improved by increasing multi-chromaticity of the NC and polymer emitters

2007-01-01

109

Controlled transport of droplets using conducting polymers.  

Science.gov (United States)

The controlled transport and delivery of dichloromethane through platinum mesh coated with dodecylbenzenesulfonate-doped polypyrrole is demonstrated upon in situ electrochemical redox switching. Droplets of dichloromethane were observed to pass freely through the mesh upon reduction of the polymer as a result of the release of the surfactant dopant into the dichloromethane and the change in the surface energy of the polymer. Planar and liquid-filled tube configurations are investigated. These concepts are envisaged to prove useful for fluid control in microfluidic devices, in the preparation of microparticles for drug delivery, and in the development of organic microreactors. PMID:19685874

Halldorsson, Jennifer A; Little, Shannon J; Diamond, Dermot; Spinks, Geoffrey; Wallace, Gordon

2009-09-15

110

Loosening Quantum Confinement: Observation of Real Conductivity Caused by Hole Polarons in Semiconductor Nanocrystals Smaller than the Bohr Radius  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We report on the gradual evolution of the conductivity of spherical CdTe nanocrystals of increasing size from the regime of strong quantum confinement with truly discrete energy levels to the regime of weak confinement with closely spaced hole states. We use the high-frequency (terahertz) real and i...

Ulbricht, R.; Pijpers, J. J. H.; Groeneveld, E.; Koole, R.; Mello Donega, C. de; Vanmaekelbergh, D.A.M.; Delerue, C.

111

A Preliminary Study of Cyclic Voltammetry of a Conducting Polymer  

Science.gov (United States)

An electroactivity study of active species in a conducting polymer uses the Cyclic Voltammetry (CV) analytical technique. A technique is chosen in which the potential of an electrode is the controlled variable, while the current is the observed variable. Two plates of platinum were used as a counting electrode and a working electrode, respectively. A reference electrode used Ag/AgCl. Polypyrrole (PPy), polythiophene (PT) and poly (3-acetic acid thiophene) (PT3AA) were conducting polymer material synthesized using iron (III) chloride as a catalyst. The effect of a supporting electrolyte of sodium perchlorate anhydrous NaClO4.H2O on conducting polymers is also studied.

Hasiah, S.; Ibrahim, K.; Senin, H. B.; Mohamed, Faizatul Shima

2007-05-01

112

High ion conducting polymer nanocomposite electrolytes using hybrid nanofillers.  

UK PubMed Central (United Kingdom)

There is a growing shift from liquid electrolytes toward solid polymer electrolytes, in energy storage devices, due to the many advantages of the latter such as enhanced safety, flexibility, and manufacturability. The main issue with polymer electrolytes is their lower ionic conductivity compared to that of liquid electrolytes. Nanoscale fillers such as silica and alumina nanoparticles are known to enhance the ionic conductivity of polymer electrolytes. Although carbon nanotubes have been used as fillers for polymers in various applications, they have not yet been used in polymer electrolytes as they are conductive and can pose the risk of electrical shorting. In this study, we show that nanotubes can be packaged within insulating clay layers to form effective 3D nanofillers. We show that such hybrid nanofillers increase the lithium ion conductivity of PEO electrolyte by almost 2 orders of magnitude. Furthermore, significant improvement in mechanical properties were observed where only 5 wt % addition of the filler led to 160% increase in the tensile strength of the polymer. This new approach of embedding conducting-insulating hybrid nanofillers could lead to the development of a new generation of polymer nanocomposite electrolytes with high ion conductivity and improved mechanical properties.

Tang C; Hackenberg K; Fu Q; Ajayan PM; Ardebili H

2012-03-01

113

Microwave assisted click chemistry on a conductive polymer film  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Microwave (MW) irradiation has been used to accelerate the functionalization of an azide functional poly(3,4-ethylenedioxythiophene) film by click chemistry. The absorption of MW energy by the conductive polymer has been exploited for localized activation of the reaction on the polymer surface. By u...

Daugaard, Anders Egede; Hansen, Thomas S.; Larsen, Niels Bent; Hvilsted, Søren

114

Current Trends in Sensors Based on Conducting Polymer Nanomaterials  

Directory of Open Access Journals (Sweden)

Full Text Available Conducting polymers represent an important class of functional organic materials for next-generation electronic and optical devices. Advances in nanotechnology allow for the fabrication of various conducting polymer nanomaterials through synthesis methods such as solid-phase template synthesis, molecular template synthesis, and template-free synthesis. Nanostructured conducting polymers featuring high surface area, small dimensions, and unique physical properties have been widely used to build various sensor devices. Many remarkable examples have been reported over the past decade. The enhanced sensitivity of conducting polymer nanomaterials toward various chemical/biological species and external stimuli has made them ideal candidates for incorporation into the design of sensors. However, the selectivity and stability still leave room for improvement.

Hyeonseok Yoon

2013-01-01

115

Polypyrrole-based conducting polymers and interactions with biological tissues  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Polypyrrole (PPy) is a conjugated polymer that displays particular electronic properties including conductivity. In biomedical applications, it is usually electrochemically generated with the incorporation of any anionic species including also negatively charged biological macromolecules such as pro...

Ateh, D.D; Navsaria, H.A; Vadgama, P

116

Conducting Polymers Functionalized with Phthalocyanine as Nitrogen Dioxide Sensors  

Directory of Open Access Journals (Sweden)

Full Text Available The conducting polymers such as polyaniline, polypyrrole and polythiophene were functionalized with copper phthalocyanine using chemical oxidation method. The obtained polymers viz. PANI-CuPc, PPy-CuPc and PT-CuPc were studied as chemical sensors by their response characteristics after exposure to various chemical vapors such as methanol, ammonia and nitrogen dioxide. The results obtained showed that these polymers have moderate sensitivity towards the methanol as well as ammonia vapors whereas they show tremendous sensitivity towards nitrogen dioxide vapors. The sensitivity factor of as high as 50,000 was obtained for PT-CuPc polymers in nitrogen dioxide. In comparison to this, the sensitivity factors of about 100 and 40 were obtained, when these polymers were exposed to ammonia and methanol vapors. The very high selectivity towards the nitrogen dioxide was explained on the basis of charge transfer complex formed between, the phthalocyanine donor and nitrogen dioxide acceptor molecules. On the other hand, ammonia becomes a competing electron donor in CuPc containing conducting polymers. The very low response towards the methanol may be explained on the basis very little charge transfer / interaction between CuPc containing polymers and methanol. Thus, CuPc incorporated conducting polymers have much higher selectivity than their original homopolymer.

S. Radhakrishnan; S. D. Deshpande

2002-01-01

117

A facile solution-phase approach to transparent and conducting ITO nanocrystal assemblies.  

UK PubMed Central (United Kingdom)

Monodisperse 11 nm indium tin oxide (ITO) nanocrystals (NCs) were synthesized by thermal decomposition of indium acetylacetonate, In(acac)(3), and tin bis(acetylacetonate)dichloride, Sn(acac)(2)Cl(2), at 270 °C in 1-octadecene with oleylamine and oleic acid as surfactants. Dispersed in hexane, these ITO NCs were spin-cast on centimeter-wide glass substrates, forming uniform ITO NC assemblies with root-mean-square roughness of 2.9 nm. The assembly thickness was controlled by ITO NC concentrations in hexane and rotation speeds of the spin coater. Via controlled thermal annealing at 300 °C for 6 h under Ar and 5% H(2), the ITO NC assemblies became conductive and transparent with the 146 nm-thick assembly showing 5.2 × 10(-3) ?·cm (R(s) = 356 ?/sq) resistivity and 93% transparency in the visible spectral range--the best values ever reported for ITO NC assemblies prepared from solution phase processes. The stable hexane dispersion of ITO NCs was also readily spin-cast on polyimide (T(g) ~360 °C), and the resultant ITO assembly exhibited a comparable conductivity and transparency to the assembly on a glass substrate. The reported synthesis and assembly provide a promising solution to the fabrication of transparent and conducting ITO NCs on flexible substrates for optoelectronic applications.

Lee J; Lee S; Li G; Petruska MA; Paine DC; Sun S

2012-08-01

118

A quantitative evaluation of metallic conduction in conjugated polymers  

CERN Multimedia

As the periodicity in crystalline materials creates the optimal condition for electronic delocalization, one might expect that in partially crystalline conjugated polymers delocalization is impeded by intergrain transport. However, for the best conducting polymers this presumption fails. Delocalization is obstructed by interchain rather than intergrain charge transfer and we propose a model of weakly coupled disordered chains to describe the physics near the metal-insulator transition. Our quantitative calculations match the outcome of recent broad-band optical experiments and provide a consistent explanation of metallic conduction in polymers.

Martens, H C F

2004-01-01

119

Interfacial ionic and electronic conductivity in polymers  

Energy Technology Data Exchange (ETDEWEB)

New phosphazen-based ((NP(OR){sub x}(OC{sub 2}H{sub 4}SO{sub 3}Na){sub 2-x}){sub n}) single ion conductors were synthesized based on a polyphosphazene backbone and short-chain polyether sidechains, some of which are terminated with tetraalkylammonium groups. These materials are good anion conductors at room temperature. Related cation conductors were also prepared and characterized. Effects of interionic attractive interactions on the diffusion of a tracer were investigated theoretically. The results are relevant to ion pairing and trapping in polymer electrolytes.

Shriver, D.F.

1989-06-01

120

Electric-Field-Induced Hopping Conductivity in Polymers  

Science.gov (United States)

The resistivity of highly insulating polymers exhibits a dependence on electric field strength. Mott and Davis as well as Poole and Frankle describe theoretically the resistivity of disordered semiconductors, when subject to a changing electric field, in terms of hopping conductivity models. Although such models have often been applied to polymers, there is little direct experimental evidence to confirm the validity of these theories when applied to polymers. We present such results for a newly-developed block co-polymer Hytrel, a highly insulating material. The constant voltage resistivity test method has been used to study Hytrel for a range of electric fields approaching electrostatic breakdown. Previously taken preliminary measurements are suggestive that Hytrel validates hopping conductivity models. With additional data we consider whether the Hytrel results are consistent with existing models of electric-field induced hopping conductivity.

Hart, Steven; Dennison, J. R.; Brunson, Jerilyn

2007-03-01

 
 
 
 
121

Synthesis of CdS nanocrystals in poly(3-hexylthiophene) polymer matrix: optical and structural studies  

International Nuclear Information System (INIS)

[en] CdS nanocrystals (NCs) were directly synthesized in P3HT matrix by decomposition of single-molecule precursor compound. In this process, a molecular precursor solution was mixed with the polymeric solution. On heating the solution to the decomposition temperature of the precursor compound, NCs were formed in situ at temperatures as low as 120 °C. The effects of the precursor concentration on the optical properties of the composite were studied. The results showed evidence of charge transfer and size variation depending on NCs concentration. CdS phase can be formed using this process at 120 °C temperature as was evident from the X-ray diffraction studies. Transmission electron microscope results confirm formation of monodispersed CdS nanoparticles of average size 4 nm. A possible mechanism of the CdS film formation was also investigated. UV–Vis measurements show that these CdS composites possess a direct band gap energy higher than 2.45 eV depending on the concentration of P3HT, indicating that the nano size can be controlled by the concentration of polymer additive in the composite. A higher concentration of P3HT showed more blue shift.

2013-01-01

122

Synthesis of CdS nanocrystals in poly(3-hexylthiophene) polymer matrix: optical and structural studies  

Energy Technology Data Exchange (ETDEWEB)

CdS nanocrystals (NCs) were directly synthesized in P3HT matrix by decomposition of single-molecule precursor compound. In this process, a molecular precursor solution was mixed with the polymeric solution. On heating the solution to the decomposition temperature of the precursor compound, NCs were formed in situ at temperatures as low as 120 Degree-Sign C. The effects of the precursor concentration on the optical properties of the composite were studied. The results showed evidence of charge transfer and size variation depending on NCs concentration. CdS phase can be formed using this process at 120 Degree-Sign C temperature as was evident from the X-ray diffraction studies. Transmission electron microscope results confirm formation of monodispersed CdS nanoparticles of average size 4 nm. A possible mechanism of the CdS film formation was also investigated. UV-Vis measurements show that these CdS composites possess a direct band gap energy higher than 2.45 eV depending on the concentration of P3HT, indicating that the nano size can be controlled by the concentration of polymer additive in the composite. A higher concentration of P3HT showed more blue shift.

Agrawal, Vikash [National Physical Laboratory, CSIR-SRF, Organic and Hybrid Solar Cell Group (India); Jain, Kiran, E-mail: kiran@mail.nplindia.org [National Physical Laboratory, Organic and Hybrid Solar Cell Group (India); Arora, Leena [Delhi Technological University, Department of Physics (India); Chand, S. [National Physical Laboratory, Organic and Hybrid Solar Cell Group (India)

2013-06-15

123

Memory effect of an organic based trilayer structure with Au nanocrystals in an insulating polymer matrix  

International Nuclear Information System (INIS)

The memory effects of gold (Au) nanocrystal (NC) non-volatile memory structures consisting of polyvinylpyrrolidone (PVP) K-30 polymer tunneling and control layers are investigated. The trilayer structure (PV P/Au-NCs + PV P/PV P) on p-type Si substrate was fabricated by spin coating, and transmission electron microscopy study reveals that the average size of the Au-NCs formed is about 5 nm in diameter. Capacitance-voltage (C-V) measurement on the memory structure shows a counter-clockwise hysteresis loop with a significant flat band voltage shift, revealing a memory effect of the Au-NCs with a charge density of up to 1 x 1012 cm-2 and a flat band voltage shift of 2.0 V. A unique feature of the double loop in the C-V curves suggests double barriers during electron tunneling. The I-V hysteresis is also characterized, and a switching mechanism of resistive change is discussed.

2010-07-23

124

White light generation tuned by dual hybridization of nanocrystals and conjugated polymers  

Energy Technology Data Exchange (ETDEWEB)

Dual hybridization of highly fluorescent conjugated polymers and highly luminescent nanocrystals (NCs) is developed and demonstrated in multiple combinations for controlled white light generation with high color rendering index (CRI) (> 80) for the first time. The generated white light is tuned using layer-by-layer assembly of CdSe/ZnS core-shell NCs closely packed on polyfluorene, hybridized on near-UV emitting nitride-based light emitting diodes (LEDs). The design, synthesis, growth, fabrication and characterization of these hybrid inorganic-organic white LEDs are presented. The following experimental realizations are reported: (i) layer-by-layer hybridization of yellow NCs ({lambda}{sub PL}=580 nm) and blue polyfluorene ({lambda}{sub PL}=439 nm) with tristimulus coordinates of (x, y)=(0.31, 0.27), correlated color temperature of T{sub c}=6962 K and CRI of R{sub a}=53.4; (ii) layer-by-layer assembly of yellow and green NCs ({lambda}{sub PL}=580 and 540 nm) and blue polyfluorene ({lambda}{sub PL}=439 nm) with (x, y)=(0.23, 0.30), T{sub c}=14395 K and R{sub a}=65.7; and (iii) layer-by-layer deposition of yellow, green and red NCs ({lambda}{sub PL}=580, 540 and 620 nm) and blue polyfluorene ({lambda}{sub PL}=439 nm) with (x, y)=(0.38, 0.39), T{sub c}=4052 K and R{sub a}= 83.0. The CRI is demonstrated to be well controlled and significantly improved by increasing multi-chromaticity of the NC and polymer emitters.

Demir, Hilmi Volkan [Devices and Sensors Group and Nanotechnology Research Center, Bilkent University, Ankara 06800 (Turkey); Nizamoglu, Sedat [Devices and Sensors Group and Nanotechnology Research Center, Bilkent University, Ankara 06800 (Turkey); Ozel, Tuncay [Devices and Sensors Group and Nanotechnology Research Center, Bilkent University, Ankara 06800 (Turkey); Mutlugun, Evren [Devices and Sensors Group and Nanotechnology Research Center, Bilkent University, Ankara 06800 (Turkey); Huyal, Ilkem Ozge [Devices and Sensors Group and Nanotechnology Research Center, Bilkent University, Ankara 06800 (Turkey); Sari, Emre [Devices and Sensors Group and Nanotechnology Research Center, Bilkent University, Ankara 06800 (Turkey); Holder, Elisabeth [Functional Polymers Group and Institute of Polymer Technology, University of Wuppertal, Gaussstrasse 20, D-42097 Wuppertal (Germany); Tian Nan [Functional Polymers Group and Institute of Polymer Technology, University of Wuppertal, Gaussstrasse 20, D-42097 Wuppertal (Germany)

2007-10-15

125

Flexible photoelectrochemical devices based on conducting polymers  

Energy Technology Data Exchange (ETDEWEB)

In this work, we have investigated the photoelectrochemical behavior of conjugated polymers in flexible solid-state devices exploring some unique features that they exhibit: the possibility of adjusting the band gap energy by employing different structures and improving the light harvesting by the addition of an organic dye. We also report the use of these materials as photoactive materials and counter-electrodes in optical devices, depending on their oxidized or reduced state. The overall conversion efficiency is higher than for other photoelectrochemical devices, which exploit the photoconductivity and photosensitivity of organic materials, and the performance remains constant when the devices are bent; however, it is low in comparison to solid-state devices using inorganic materials. (orig.)

Gazotti, W.A.; Nogueira, A.F.; Girotto, E.M. [Universidade Estadual de Campinas (Brazil). Inst. de Quimica; Gallazzi, M.C. [Dipartimento di Chimica Industriale e Ingegneria Chimica, Politecnico di Milano, Piazza L. Da Vinci 32, Milan (Italy); De Paoli, M.-A. [Laboratorio de Polimeros Condutores e Reciclagem, Instituto de Quimica, Universidade Estadual de Campinas, C. Postal 6154, Campinas (Brazil)

2000-01-17

126

Light harvesting by dye linked conducting polymers  

DEFF Research Database (Denmark)

The fact that the fossil fuel is finite and that the detrimental long-term effects of letting CO2 into our atmosphere exist, have created an enormous interest in developing new, cheap, renewable and less polluting energy resources. One of the most obviousabundant sources of energy in the solar system is the sun. Unfortunately the well developed silicon solar cells are very costly to produce. In an attempt to produce cheap and flexible solar cells, plastic solar cells have received a lot of attention inthe last decades. There are still a lot of parameters to optimize if the plastic solar cell shall be able to compete with the silicon solar cells. One of the parameters is to ensure a high degree of charge carrier separation. Charge carrier separationcan only happen at heterojunctions, which cover for example the interfaces between the polymers and the electrodes or the interface between an nconductor and a pconductor. The facts that the charge carrier separation only happens at the heterojunctionslimits the thickness of the active layer in solar cells and thereby the effectiveness of the solar cells. In this project the charge carrier separation is attempted optimized by making plastic solar cells with a molecular heterojunction. The molecularheterojunction has been obtained by synthesizing a three domain super molecular assembly termed NPN. NPN consists of two poly[1-(2,5- dioctyltolanyl)ethynylene] chains (N-domains) coupled to the [10,20- bis(3,5-bistert-butylphenyl]-5,15-dibromoporphinato]zinc(II) (P-domain). It is shown that the N domains in NPN work as effective light harvesting antennas for the P domain and effectively transfer electrically generated excitons in the N domain to the P domain.Unfortunately the P domain does not separate the charge carriers but instead works as a charge carrier trap. This results in a performance of solar cells made of NPN that is much lower than the performance of solar cells made of pure poly[1-(2,5-dioctyltolanyl)- ethynylene], Nn. On the other hand light emitting diodes, LEDs, made of Nn and NPN works very well. The LEDs made of Nn emits greenish blue light while LEDs made of NPN emits light in the nearinfrared region. During the synthesis of Nnand NPN it was found that remnants of the palladium catalysts caused problems in the control of the polymers and further made the resistance in the solar cells and LEDs so low that they did not work. A large effort has been made during the project todevelop a method to remove remnants of metal catalysts from organic compounds and in particular polymers so that functional solar cells and LEDs could be made. It was succeeded to find a very effective method to remove remnants of metal catalysts fromorganic compounds by the discovery of the fact that azothioformamides are capable of dissolving metal nanoparticles by forming electron transfer complexes. Even metal wires of some metals can be dissolved by the azothioformamides within a reasonable timerange.

Nielsen, Kim Troensegaard

2006-01-01

127

Light harvesting by dye linked conducting polymers  

Energy Technology Data Exchange (ETDEWEB)

The fact that the fossil fuel is finite and that the detrimental long-term effects of letting CO2 into our atmosphere exist, have created an enormous interest in developing new, cheap, renewable and less polluting energy resources. One of the most obvious abundant sources of energy in the solar system is the sun. Unfortunately the well developed silicon solar cells are very costly to produce. In an attempt to produce cheap and flexible solar cells, plastic solar cells have received a lot of attention in the last decades. There are still a lot of parameters to optimize if the plastic solar cell shall be able to compete with the silicon solar cells. One of the parameters is to ensure a high degree of charge carrier separation. Charge carrier separation can only happen at heterojunctions, which cover for example the interfaces between the polymers and the electrodes or the interface between an n-conductor and a p-conductor. The facts that the charge carrier separation only happens at the heterojunctions limits the thickness of the active layer in solar cells and thereby the effectiveness of the solar cells. In this project the charge carrier separation is attempted optimized by making plastic solar cells with a molecular heterojunction. The molecular heterojunction has been obtained by synthesizing a three domain super molecular assembly termed NPN. NPN consists of two poly[1-(2,5-dioctyltolanyl)ethynylene] chains (N-domains) coupled to the [10,20-bis(3,5-bistert-butylphenyl]-5,15-dibromoporphinato]zinc(II) (P-domain). It is shown that the N domains in NPN work as effective light harvesting antennas for the P domain and effectively transfer electrically generated excitons in the N domain to the P domain. Unfortunately the P domain does not separate the charge carriers but instead works as a charge carrier trap. This results in a performance of solar cells made of NPN that is much lower than the performance of solar cells made of pure poly[1-(2,5-dioctyltolanyl)- ethynylene], Nn. On the other hand light emitting diodes, LEDs, made of Nn and NPN works very well. The LEDs made of Nn emits greenish blue light while LEDs made of NPN emits light in the near-infrared region. During the synthesis of Nn and NPN it was found that remnants of the palladium catalysts caused problems in the control of the polymers and further made the resistance in the solar cells and LEDs so low that they did not work. A large effort has been made during the project to develop a method to remove remnants of metal catalysts from organic compounds and in particular polymers so that functional solar cells and LEDs could be made. It was succeeded to find a very effective method to remove remnants of metal catalysts from organic compounds by the discovery of the fact that azothioformamides are capable of dissolving metal nanoparticles by forming electron transfer complexes. Even metal wires of some metals can be dissolved by the azothioformamides within a reasonable time range. (au)

Troensegaard Nielsen, K.

2006-06-15

128

Conductivity percolation in polyiodide/polymer complexes  

Energy Technology Data Exchange (ETDEWEB)

Variable-temperature four-probe conductivity measurements and Raman spectroscopy were investigated for iodine in poly(propylene oxide) (PPO) and NaI[sub 3] in PPO. The Raman spectra indicate the presence of both triiodide and polyiodide species in samples of I[sub 2]-doped PPO. The conductivity of these PPO/I[sub 2] samples increased with increasing I[sub 2] concentration and reached a plateau at approximately 12 vol % iodine. Raman spectra at 20 [degrees]C indicate that, at concentrations less than 23 vol% I[sup [minus][sub 3

Forsyth, M.; Shriver, D.F.; Ratner, M.A.; DeGroot, D.C.; Kannewurf, C.R. (Northwestern Univ., Evanston, IL (United States))

1993-08-01

129

A computer simulation study of ionic conductivity in polymer electrolytes  

CERN Multimedia

In this paper we present a computer simulation study of ionic conductivity in solid polymeric electrolytes. The multiphase nature of the material is taken into account. The polymer is represented by a regular lattice whose sites represent either crystalline or amorphous regions with the charge carrier performing a random walk. Different waiting times are assigned to sites corresponding to the different phases. A random walk (RW) is used to calculate the conductivity through the Nernst-Einstein relation. Our walk algorithm takes into account the reorganisation of the different phases over time scales comparable to time scales for the conduction process. This is a characteristic feature of the polymer network. The qualitative nature of the variation of conductivity with salt concentration agrees with the experimental values for PEO-NH$_{4}$I and PEO-NH$_{4}$SCN. The average jump distance estimated from our work is consistent with the reported bond lengths for such polymers.

Bhattacharya, A J; Tarafdar, S; Bhattacharyya, Aninda Jiban

1997-01-01

130

Anisotropic growth of conducting polymers along heparin-modified surfaces.  

UK PubMed Central (United Kingdom)

We have studied the possibility of making biocompatible, conductive patterns on a substrate by controlling the lateral growth rate of conducting polymers upon electropolymerization. Surface modification with heparin was found to enhance the lateral growth of polypyrrole, especially in the presence of dodecylbenzenesulfonate, and thus the micropatterning of heparin around electrodes leads to the formation of polypyrrole patterns.

Nishizawa M; Kamiya T; Nozaki H; Kaji H

2007-07-01

131

Effect of crosslink formation on heat conduction in amorphous polymers  

Science.gov (United States)

We performed molecular dynamics (MD) simulations on amorphous polyethylene (PE) and polystyrene (PS) in order to elucidate the effect of crosslinks between polymer chains on heat conduction. In each polymer system, thermal conductivities were measured for a range of crosslink concentration by using nonequilibrium MD techniques. PE comprised of 50 carbon atom long chains exhibited slightly higher conductivity than that of 250 carbon atom long chains at the standard state. In both cases for PE, crosslinking significantly increased conductivity and the increase was more or less proportional to the crosslink density. On the other hand, in the PS case, although the thermal conductivity increased with the crosslinking, the magnitude of change in thermal conductivity was relatively small. We attribute this difference to highly heterogeneous PS based network including phenyl side groups. In order to elucidate the mechanism for the increase of thermal conductivity with the crosslink concentration, we decomposed energy transfer into modes associated with various bonded and non-bonded interactions.

Kikugawa, Gota; Desai, Tapan G.; Keblinski, Pawel; Ohara, Taku

2013-07-01

132

Electrochemical sensors based on conducting polymer-polypyrrole  

Energy Technology Data Exchange (ETDEWEB)

Conducting polymers can be exploited as an excellent tool for the preparation of nanocomposites with nano-scaled biomolecules. Polypyrrole (Ppy) is one of the most extensively used conducting polymers in design of bioanalytical sensors. In this review article significant attention is paid to immobilization of biologically active molecules within Ppy during electrochemical deposition of this polymer. Such unique properties of this polymer as prevention of some undesirable electrochemical interactions and facilitation of electron transfer from some redox enzymes are discussed. Recent advances in application of polypyrrole in immunosensors and DNA sensors are presented. Some new electrochemical target DNA and target protein detection methods based on changes of semiconducting properties of electrochemically generated Ppy doped by affinity agents are introduced. Recent progress and problems in development of molecularly imprinted polypyrrole are considered.

Ramanavicius, A. [Department of Analytical and Environmental Chemistry, Vilnius University, Naugarduko 24, 03225 Vilnius (Lithuania) and Laboratory of Immunoanalysis and Nanotechnology, Institute of Immunology of Vilnius University, Moletu pl. 29, 08409 Vilnius (Lithuania)]. E-mail: arunas@imi.lt; Ramanaviciene, A. [Department of Analytical and Environmental Chemistry, Vilnius University, Naugarduko 24, 03225 Vilnius (Lithuania); Laboratory of Immunoanalysis and Nanotechnology, Institute of Immunology of Vilnius University, Moletu pl. 29, 08409 Vilnius (Lithuania); Malinauskas, A. [Department of Organic Chemistry, Institute of Chemistry, Gostauto 9, 01108 Vilnius (Lithuania)

2006-08-25

133

TiO2 nanocrystals shell layer on highly conducting indium tin oxide nanowire for photovoltaic devices  

Science.gov (United States)

We demonstrated a highly efficient conducting indium tin oxide (ITO) core-TiO2 nanocrystals shell nanowire array for a photoelectrode in dye-sensitized solar cells with regard to light harvest and charge collection. The TiO2 shell layer, consisting of anatase nanocrystals of ~2 nm, were successfully formed on a single crystalline ITO nanowire prepared via a vapor transport method using repetitive TiCl4 aqueous solution treatments at 50 °C. We found that the nanocrystal size and number of Cl- ions remaining on the formed shell layer critically influence the dye loading properties. Moreover, these factors can be controlled by means of a post-annealing process. We also found that the dye loading and the back electron transport from the conductive ITO nanowire to the electrolyte mainly determine the final cell performance. The proposed double-shell layer structure consisting of dense and porous layers showed significantly improved cell performance.We demonstrated a highly efficient conducting indium tin oxide (ITO) core-TiO2 nanocrystals shell nanowire array for a photoelectrode in dye-sensitized solar cells with regard to light harvest and charge collection. The TiO2 shell layer, consisting of anatase nanocrystals of ~2 nm, were successfully formed on a single crystalline ITO nanowire prepared via a vapor transport method using repetitive TiCl4 aqueous solution treatments at 50 °C. We found that the nanocrystal size and number of Cl- ions remaining on the formed shell layer critically influence the dye loading properties. Moreover, these factors can be controlled by means of a post-annealing process. We also found that the dye loading and the back electron transport from the conductive ITO nanowire to the electrolyte mainly determine the final cell performance. The proposed double-shell layer structure consisting of dense and porous layers showed significantly improved cell performance. Electronic supplementary information (ESI) available: Raman spectra of the as-prepared core-shell nanowire and the calculated band-gaps of the samples according to the UV-vis absorption spectra. See DOI: 10.1039/c3nr33153a

Han, Hyun Soo; Kim, Ju Seong; Kim, Dong Hoe; Han, Gil Sang; Jung, Hyun Suk; Noh, Jun Hong; Hong, Kug Sun

2013-03-01

134

Ionic motion in PEDOT and PPy conducting polymer bilayers  

DEFF Research Database (Denmark)

Conducting polymer bilayers with poly(3,4-ethylenedioxythiophene) (PEDOT) and polypyrrole (PPy), each containing dodecyl benzenesulfonate (DBS) as immobile dopant species, were synthesized galvanostatically. The electrochemical behaviour of the bilayers was investigated using cyclic voltammetry, optical absorption spectroscopy and electrochemical quartz crystal microbalance (EQCM) techniques. Two important conclusions of relevance for actuator performance were reached: It is possible to make a bilayer film that does not delaminate – the two polymers are compatible; and both polymers are active in the redox process as ions are able to move through the PEDOT layer and penetrate into PPy.

Zainudeen, Umer L.; Careem, M.A.

2006-01-01

135

Mixed-ionic and electronic conductivity in polymers  

Energy Technology Data Exchange (ETDEWEB)

The aim in this portion of the research is to prepare new electroactive films with high ion mobility, and to characterize the transport properties of these materials. The classic conducting polymers, polyacetylene, polythiophene, and polypyrrole have dense structures that prevent rapid redox switching because of the low diffusivity of ions. The objective is to modify the last two polymers with pendant polyethers, which should greatly improve ion transport.

Ratner, M.A.; Shriver, D.F.

1991-01-01

136

Multifunctional polymer-derivatized ?-Fe2O3 nanocrystals as a methodology for the biomagnetic separation of recombinant His-tagged proteins  

International Nuclear Information System (INIS)

Multifunctional polymer-derivatized superparamagnetic iron oxide (?-Fe2O3) nanoparticles were prepared for biomagnetic separation of histidine-tagged recombinant proteins building up a faster and efficient method for protein separation by making use of their intrinsic magnetic properties. Using polymer bound ?-Fe2O3 nanocrystals, a 6x histidine-tagged recombinant protein (silicatein) with a molecular weight of 24 kDa has been isolated and purified. The supermagnetic iron oxide nanocrystals were characterized by transmission electron microscopy (TEM), high-resolution TEM (HRTEM), SQUID and Moessbauer and the polymer functionalization of the ?-Fe2O3 nanocrystals was monitored by UV-vis spectroscopy and light microscopy. Protein immobilization and separation was monitored using immunostaining techniques and gel electrophoresis, respectively.

2008-01-01

137

Transition metal oxide/organic hybrids and conductive polymer nanocomposites  

Energy Technology Data Exchange (ETDEWEB)

Transition metal oxides are used as cathode materials in the latest generation of rechargeable lithium batteries. Two problems that are encountered, however, are low electronic conductivity of the inorganic oxide over some regions of the redox range, and relatively poor lithium ion transport properties compared to other materials. A possibility for enhancing and expanding the range of the electronic conductivity of the metal oxide host material is to interleave conductive polymer chains between the atomic sheets of a layered inorganic oxide to create a polymer/oxide nanocomposite. Alternatively, there is much interest in the generation of {open_quotes}open-framework{close_quotes} inorganic structures that have the potential for less hindered Li ion mobility. This talk will address both approaches with illustrations from our recent work. The first portion will focus on structure-property relationships in new polymer-oxide nanocomposites of transition metal oxides (Mo, Ta, V) and conductive polymers. The second portion will discuss {open_quotes}open-framework{close_quotes} transition metal (Mn, V, MO) oxide/organic hybrid structures as hosts for Li ion insertion. The characterization of these materials using diffraction, thermal analysis, TEM, and conductivity measurements will be presented. In particular, the electrochemical properties of both types of materials will be presented, outlining the effect of the polymer on electrochemical lithium insertion reactions in the layered oxide hosts; and the effect of structure and organic guest species in hydrothermally-generated transition metal oxides.

Nazar, L.F.; Kerr, T.; Koene, B.; Duncan, M.J.; Leroux, F. [Univ. of Waterloo, Ontario (Canada)

1996-10-01

138

Synthesis of novel metallocenes: Asymmetric hydrogenation catalysts to conductive polymers  

Energy Technology Data Exchange (ETDEWEB)

The goal of this research was to synthesize conductive polymers based on repeating ferrocene units. During the course of this study, the design of the conductive polymers evolved from the initial model based on [open quotes]stacked[open quotes] ferrocenes where ethano bridged cyclophentadienyl rings are linked by iron(II), to the latest ferrocene-diene model where ferrocene units were linked by double bonds. In the pursuit of these elusive monomers, attempts at their synthesis led down dead-end routes, even though new molecules were synthesized. Some of these dead-end routes, even though new molecules were synthesized. All the work reported in this dissertation had the eventual goal of synthesizing potential monomers for ferrocene conductive polymers. This dissertation is divided into three chapters. Chapter one describes the attempted synthesis of thiophene derivatives where a cyclopentadienyl ring is fused to the [c]-face. Although the target molecule was never synthesized, a convenient and safe new synthesis of 3,4-dibromo=2,5-dimethyl thiophene was developed along with the synthesis and full characterization of 3-bromo-4-trimethylsilyl-2,5-dimethylthiophene. Chapter two describes the design of asymmetric hydrogenation catalysts and the convenient synthesis of chiral titanocene derivatives. Chapter three summarizes the history of the attempts to prepare ferrocene containing conductive polymers and describes the synthesis of ferrocenophenes and diethano bridged bis(cyclophentadienyl) compounds for use as monomeric precursors to conductive polymers based on repeating ferrocene units.

Erickson, M.S.

1992-01-01

139

Hexavalent chromium removal mechanism using conducting polymers.  

UK PubMed Central (United Kingdom)

We report detoxification of Cr(VI) into Cr(III) using electrochemically synthesized polyaniline (PANI), polypyrrole (PPY), PANI nanowires (PANI-NW) and palladium-decorated PANI (PANI-Pd) thin films. Percent Cr(VI) reduction was found to be decreased with an increase in pH from 1.8 to 6.8 and with initial Cr(VI) concentration ranging from 2.5 to 10mg/L. Efficacy of PANI increased at higher temp of 37 °C as compared to 30 °C. PANI-Pd was found to be most effective for all three initial Cr(VI) concentrations at pH 1.8. However, efficacy of PANI-Pd was significantly reduced at higher pHs of 5 and 6.8. Efficacy of PANI and PANI-NW was found to nearly the same. However, there was a significant reduction in effectiveness of PANI-NW at 10mg/L of Cr(VI) at all the three pHs studied, which could be attributed to degradation of PANI-NW by higher initial Cr(VI) concentration. PPY and PANI-NW were found to be highly sensitive with respect to pH and Cr(VI) initial concentration. Chromium speciation on PANI film was carried out by total chromium analysis and XPS, which revealed Cr(III) formation and its subsequent adsorption on the polymer. PANI-Pd and PANI are recommended for future sensor applications for chromium detection at low pH.

Krishnani KK; Srinives S; Mohapatra BC; Boddu VM; Hao J; Meng X; Mulchandani A

2013-05-01

140

Hexavalent chromium removal mechanism using conducting polymers.  

Science.gov (United States)

We report detoxification of Cr(VI) into Cr(III) using electrochemically synthesized polyaniline (PANI), polypyrrole (PPY), PANI nanowires (PANI-NW) and palladium-decorated PANI (PANI-Pd) thin films. Percent Cr(VI) reduction was found to be decreased with an increase in pH from 1.8 to 6.8 and with initial Cr(VI) concentration ranging from 2.5 to 10mg/L. Efficacy of PANI increased at higher temp of 37 °C as compared to 30 °C. PANI-Pd was found to be most effective for all three initial Cr(VI) concentrations at pH 1.8. However, efficacy of PANI-Pd was significantly reduced at higher pHs of 5 and 6.8. Efficacy of PANI and PANI-NW was found to nearly the same. However, there was a significant reduction in effectiveness of PANI-NW at 10mg/L of Cr(VI) at all the three pHs studied, which could be attributed to degradation of PANI-NW by higher initial Cr(VI) concentration. PPY and PANI-NW were found to be highly sensitive with respect to pH and Cr(VI) initial concentration. Chromium speciation on PANI film was carried out by total chromium analysis and XPS, which revealed Cr(III) formation and its subsequent adsorption on the polymer. PANI-Pd and PANI are recommended for future sensor applications for chromium detection at low pH. PMID:23507365

Krishnani, K K; Srinives, Sira; Mohapatra, B C; Boddu, V M; Hao, Jumin; Meng, X; Mulchandani, Ashok

2013-02-19

 
 
 
 
141

Anhydrous proton conductivity of acid doped vinyltriazole-based polymers  

Energy Technology Data Exchange (ETDEWEB)

Poly(1,2,4-vinyltriazole) (PVTr) and poly(1,2,4-vinyltriazole-co-5-vinyltetrazole-co-acrylonitrile) (P(VTr-VT-AN)) were prepared by normal free radical polymerization and click chemistry, respectively. The structure of the polymers was characterized by FTIR spectra, H NMR spectrum and elemental analysis. Compared with polybenzimidazole (PBI) which is one of the most widely studied anhydrous proton conducting polymers, the solubility of vinyltriazole-based polymers is improved significantly. They are soluble in a lot of polar solvents. The glass-transition temperatures of such kind of polymers are between 70 and 85 C, thus indirectly indicating the improvement of fabricating properties. In phosphoric acid doped membranes, the higher the basicity of the vinyltriazole-based polymers is, the higher the proton conductivity is. The temperature dependence of the proton conductivity of the acid doped membranes can always be fitted by a simple Arrhenius equation. Transmittance of phosphoric acid doped vinyltriazole-based polymers is above 80% in the range of visual spectra and changes a little with the different structure and basicity of the copolymers. (author)

Pu, Hongting; Ye, Sheng [Institute of Functional Polymers, School of Materials Science and Engineering, Tongji University, Shanghai 200092 (China); Wan, Decheng [Institute of Functional Polymers, School of Materials Science and Engineering, Tongji University, Shanghai 200092 (China); Key Laboratory of Advanced Civil Engineering Materials, Ministry of Education, Shanghai 200092 (China)

2007-05-25

142

Anhydrous proton conductivity of acid doped vinyltriazole-based polymers  

International Nuclear Information System (INIS)

Poly(1,2,4-vinyltriazole) (PVTr) and poly(1,2,4-vinyltriazole-co-5-vinyltetrazole-co-acrylonitrile) (P(VTr-VT-AN)) were prepared by normal free radical polymerization and click chemistry, respectively. The structure of the polymers was characterized by FTIR spectra, H NMR spectrum and elemental analysis. Compared with polybenzimidazole (PBI) which is one of the most widely studied anhydrous proton conducting polymers, the solubility of vinyltriazole-based polymers is improved significantly. They are soluble in a lot of polar solvents. The glass-transition temperatures of such kind of polymers are between 70 and 85 oC, thus indirectly indicating the improvement of fabricating properties. In phosphoric acid doped membranes, the higher the basicity of the vinyltriazole-based polymers is, the higher the proton conductivity is. The temperature dependence of the proton conductivity of the acid doped membranes can always be fitted by a simple Arrhenius equation. Transmittance of phosphoric acid doped vinyltriazole-based polymers is above 80% in the range of visual spectra and changes a little with the different structure and basicity of the copolymers.

2007-05-25

143

Study of PEDOT conductive polymer films by admittance measurements  

International Nuclear Information System (INIS)

[en] Research highlights: ? Microwave technique to measure the conductivity of PEDOT films. ? PEDOT conductivity depends on its mesoscopic scale structure and oxidation level. ? Raman spectroscopy and SEM analysis to study structure and morphology of PEDOT. ? Microwave measurements allow determination of the macroscopic scale conductivity. ? Microwave measurements overcome problems related to the local structural defects and inhomogeneities of PEDOT. - Abstract: In this paper we propose the use of a microwave technique to measure the conductivity of poly(3,4-ethylenedioxythiophene) (PEDOT) films. The PEDOT layers were prepared by electropolymerization from aqueous solutions using both poly(sodium 4-styrene sulphonate) (NaPSS) and sodium dodecyl sulphate (NaDS) acting as monomer solubilizer and dopant for the polymer. The conductive properties of a series of samples produced under different synthesis conditions and characterized by different structures have been investigated by microwave measurements in the frequency range from 40 MHz to 40 GHz by using a Corbino disc geometry. Such technique allows to estimate the mean conductivity of the polymer samples overcoming the limitations of the measuring configurations typically imposed by the conventional d.c. measurements. The morphology of PEDOT films and the structure of polymer chains were studied by scanning electron microscopy (SEM) and Raman spectroscopy, respectively. The correlated morphological, structural and microwave analysis enabled us to evidence several factors that affect the macroscopic scale conductivity of the polymer sample films and to identify the conditions for preparation of PEDOT films with functional properties relevant to technological applications.

2011-02-15

144

Study of PEDOT conductive polymer films by admittance measurements  

Energy Technology Data Exchange (ETDEWEB)

Research highlights: {yields} Microwave technique to measure the conductivity of PEDOT films. {yields} PEDOT conductivity depends on its mesoscopic scale structure and oxidation level. {yields} Raman spectroscopy and SEM analysis to study structure and morphology of PEDOT. {yields} Microwave measurements allow determination of the macroscopic scale conductivity. {yields} Microwave measurements overcome problems related to the local structural defects and inhomogeneities of PEDOT. - Abstract: In this paper we propose the use of a microwave technique to measure the conductivity of poly(3,4-ethylenedioxythiophene) (PEDOT) films. The PEDOT layers were prepared by electropolymerization from aqueous solutions using both poly(sodium 4-styrene sulphonate) (NaPSS) and sodium dodecyl sulphate (NaDS) acting as monomer solubilizer and dopant for the polymer. The conductive properties of a series of samples produced under different synthesis conditions and characterized by different structures have been investigated by microwave measurements in the frequency range from 40 MHz to 40 GHz by using a Corbino disc geometry. Such technique allows to estimate the mean conductivity of the polymer samples overcoming the limitations of the measuring configurations typically imposed by the conventional d.c. measurements. The morphology of PEDOT films and the structure of polymer chains were studied by scanning electron microscopy (SEM) and Raman spectroscopy, respectively. The correlated morphological, structural and microwave analysis enabled us to evidence several factors that affect the macroscopic scale conductivity of the polymer sample films and to identify the conditions for preparation of PEDOT films with functional properties relevant to technological applications.

Tamburri, Emanuela, E-mail: Emanuela.Tamburri@uniroma2.it [Dip.to di Scienze e Tecnologie Chimiche and Interdisciplinary Micro and NAno-structured Systems laboratory (MINAS), Universita di Roma ' Tor Vergata' , Via Della Ricerca Scientifica, 00133 Roma (Italy); Sarti, Stefano [Dip.to di Fisica, Universita di Roma ' Sapienza' , P.le Aldo Moro 2, 00185 Roma (Italy); Orlanducci, Silvia; Terranova, Maria Letizia [Dip.to di Scienze e Tecnologie Chimiche and Interdisciplinary Micro and NAno-structured Systems laboratory (MINAS), Universita di Roma ' Tor Vergata' , Via Della Ricerca Scientifica, 00133 Roma (Italy); Rossi, Marco [Dip. di Scienze di Base e Applicate per l' Ingegneria, Universita di Roma ' Sapienza' , Via A. Scarpa 16, 00161 Roma (Italy)

2011-02-15

145

Preparation of Conducting Polymers by Electrochemical Methods and Demonstration of a Polymer Battery  

Science.gov (United States)

|The electrochemical polymerization of aniline and pyrrole, and demonstrations of electrochromism and the polymer battery effect, are presented as demonstrations suitable for high school and introductory chemistry at the university level. These demonstrations promote student interest in the electrochemical preparation of conducting polymers, where…

Goto, Hiromasa; Yoneyama, Hiroyuki; Togashi, Fumihiro; Ohta, Reina; Tsujimoto, Akitsu; Kita, Eiji; Ohshima, Ken-ichi

2008-01-01

146

Corrosion resistant coatings from conducting polymers  

Energy Technology Data Exchange (ETDEWEB)

Cr-based corrosion resistant undercoatings will have to be replaced because of environmental and health concerns. A coating system of a conducting polyaniline primer layer topcoated with epoxy or polyurethane, is being evaluated for corrosion resistance on mild steel in 0.1 M HCl or in a marine setting. Results of both laboratory and Beach Site testing indicate that this coating is very effective; even when the coatings are scratched to expose bare metal, the coated samples show very little signs of corrosion in the exposed area. 3 figs, 6 refs.

Wrobleski, D.A.; Benicewicz, B.C. [Los Alamos National Lab., NM (United States); Thompson, K.G.; Bryan, C.J. [National Aeronautics and Space Administration, Cocoa Beach, FL (United States). John F. Kennedy Space Center

1993-12-01

147

Magnetic field directed fabrication of conducting polymer nanowires.  

UK PubMed Central (United Kingdom)

The self-assembly of nanoparticles is an efficient and precise method to fabricate nanoscale devices. By manipulating iron oxide nanoparticles in suspension with an external field to form magnetically directed linear assemblies, we demonstrate the feasibility of using this structure to template the synthesis of PEDOT:PSS conducting polymer nanowires in suspension. Furthermore these conducting wires can be assembled on interdigitated electrodes to form an array of conducting nanowires.

Ho D; Peerzade SA; Becker T; Hodgetts SI; Harvey AR; Plant GW; Woodward RC; Luzinov I; St Pierre TG; Iyer KS

2013-07-01

148

Magnetic field directed fabrication of conducting polymer nanowires.  

Science.gov (United States)

The self-assembly of nanoparticles is an efficient and precise method to fabricate nanoscale devices. By manipulating iron oxide nanoparticles in suspension with an external field to form magnetically directed linear assemblies, we demonstrate the feasibility of using this structure to template the synthesis of PEDOT:PSS conducting polymer nanowires in suspension. Furthermore these conducting wires can be assembled on interdigitated electrodes to form an array of conducting nanowires. PMID:23831765

Ho, Dominic; Peerzade, Saquib Ahmed M A; Becker, Thomas; Hodgetts, Stuart I; Harvey, Alan R; Plant, Giles W; Woodward, Robert C; Luzinov, Igor; St Pierre, Timothy G; Iyer, K Swaminathan

2013-08-18

149

Recent developments in intrinsically conductive polymer coatings for corrosion protection  

Directory of Open Access Journals (Sweden)

Full Text Available Intrinsically conductive polymers have achieved demanding interest in the field of corrosion control coatings owing to their conductive ability and also due to the strict environmental regulations on conventional heavy metals coatings. This multipurpose class of polymers has shown to be effective and proven themselves as a potential alternate for these hazardous heavy metal coatings in order to control the corrosion properties of metals or alloys. The basic purpose of this paper is only to highlight the past decade work relating to the efforts made on protection of metals from corrosion using conductive polymers. The categorization of the coatings is based on the techniques used to apply them. This paper will also discuss the synthesis and prospective applications of these coatings depending on their different formation techniques.

M. I. Khan; Ali Usman Chaudhry; S. Hashim; M. K. Zahoor; M. Z. Iqbal

2010-01-01

150

Ion-Conducting Polymer Films as Chemical Sensors  

Energy Technology Data Exchange (ETDEWEB)

Solid Polymer Electrolytes (SPE) are widely used in batteries and fuel cells because of the high ionic conductivity that can be achieved at room temperature. The ions are usually Li or protons, although other ions can be shown to conduct in these polymer films. There has been very little work on using these films as chemical sensors. We have found that thin films of polymers like polyethyleneoxide (PEO) are very sensitive to low concentrations of volatile organic compounds (VOCS) like common solvents. We will present impedance spectroscopy of PEO films in the frequency range 0.01 Hz to 1 MHz for different concentrations of VOCS. We find that the measurement frequency is important for distinguishing ionic conductivity from the double layer capacitance and parasitic capacitances.

Hughes, R.C.; Patel, S.V.; Pfeifer, K.B.; Yelton, W.G.

1999-05-03

151

Structure of ?-ET2I3 in conducting polymer films  

International Nuclear Information System (INIS)

It is shown by X-ray diffraction studies that polycrystalline ?-ET2I3 obtained within a surface layer of polymer film exists in states with different interlayer spacing depending on preparation conditions. The differences of spacing can be as large as 0.1 A and are due to a stress in polycrystalline layer arising during polymer film solidification. The microcrystallites of ?-ET2I3 with larger interlayer spacing can be transformed into equilibrium state with smaller spacing by a treatment of the composite leading to the relaxation of the stress, i.e., annealing or exposure to the vapours of solvent able to swell the polymer. Preliminary studies indicate that the stress in conducting polymer/organic crystals composites has an important influence on their electrical properties. (orig.)

2000-03-01

152

Mechanism of actuation in conducting polymers: Osmotic expansion  

DEFF Research Database (Denmark)

Conducting polymers expand or contract when their redox state is changed. This expansion/contraction effect can be separated in an intrinsic part because of changes of the polymer backbone on reduction/oxidation and a part depending on the surrounding electrolyte phase, because of osmotic expansion of the polymer phase. The osmotic effect causes solvent molecules to move into the polymer in a number far in excess of those bound strongly in the solvation shell of the mobile ion, resulting in large volume changes. In this paper, a thermodynamic description of the osmotic expansion is worked out. The model is compared with measurements on PPy(DBS) films. The experiments show that the expansion decreases as the electrolyte concentration is increased. This means that a considerable part of the total expansion is due to the osmotic effect. The osmotic effect should be taken into account when interpreting and designing actuator experiments and when comparing experimental results from different sources.

Bay, Lasse; Jacobsen, Torben

2001-01-01

153

Thin film conductive polymer for microactuator and micromuscle applications  

Energy Technology Data Exchange (ETDEWEB)

Conductive polymer/polyimide bimorphic microcantilevers have been actuated vertically (out-of-plane) upon the volumetric changes induced by electrochemical doping of the polymer. The microcantilevers that are 200-500 {mu}m in length and 50-100 {mu}m in width can be fully extended from a circularly-curled geometry, and thus generate more than 100 {mu}m displacement. Dynamically the microcantilevers have been driven as fast as 1.2 Hz and the polymer was stable for over a week stored in air and light. Residual stresses in the polymer film is estimated to be as high as 254 MPa, and actuation stresses are as high as 50 MPa.

Lee, A.P.; Hong, K.; Trevino, J.; Northrup, M.A.

1994-04-14

154

EFFECTS OF TRITIUM GAS EXPOSURE ON ELECTRICALLY CONDUCTING POLYMERS  

Energy Technology Data Exchange (ETDEWEB)

Effects of beta (tritium) and gamma irradiation on the surface electrical conductivity of two types of conducting polymer films are documented to determine their potential use as a sensing and surveillance device for the tritium facility. It was shown that surface conductivity was significantly reduced by irradiation with both gamma and tritium gas. In order to compare the results from the two radiation sources, an approximate dose equivalence was calculated. The materials were also sensitive to small radiation doses (<10{sup 5} rad), showing that there is a measurable response to relatively small total doses of tritium gas. Spectroscopy was also used to confirm the mechanism by which this sensing device would operate in order to calibrate this sensor for potential use. It was determined that one material (polyaniline) was very sensitive to oxidation while the other material (PEDOT-PSS) was not. However, polyaniline provided the best response as a sensing material, and it is suggested that an oxygen-impermeable, radiation-transparent coating be applied to this material for future device prototype fabrication. A great deal of interest has developed in recent years in the area of conducting polymers due to the high levels of conductivity that can be achieved, some comparable to that of metals [Gerard 2002]. Additionally, the desirable physical and chemical properties of a polymer are retained and can be exploited for various applications, including light emitting diodes (LED), anti-static packaging, electronic coatings, and sensors. The electron transfer mechanism is generally accepted as one of electron 'hopping' through delocalized electrons in the conjugated backbone, although other mechanisms have been proposed based on the type of polymer and dopant [Inzelt 2000, Gerard 2002]. The conducting polymer polyaniline (PANi) is of particular interest because there are extensive studies on the modulation of the conductivity by changing either the oxidation state of the main backbone chain, or by protonation of the imine groups [de Acevedo, 1999]. There are several types of radiation sensors commercially available, including ionization chambers, geiger counters, proportional counters, scintillators and solid state detectors. Each type has advantages, although many of these sensors require expensive electronics for signal amplification, are large and bulky, have limited battery life or require expensive materials for fabrication. A radiation sensor constructed of a polymeric material could be flexible, light, and the geometry designed to suit the application. Very simple and inexpensive electronics would be necessary to measure the change in conductivity with exposure to radiation and provide an alarm system when a set change of conductivity occurs in the sensor that corresponds to a predetermined radiation dose having been absorbed by the polymer. The advantages of using a polymeric sensor of this type rather than those currently in use are the flexibility of sensor geometry and relatively low cost. It is anticipated that these sensors can be made small enough for glovebox applications or have the ability to monitor the air tritium levels in places where a traditional monitor cannot be placed. There have been a few studies on the changes in conductivity of polyaniline specifically for radiation detection [de Acevedo, 1999; Lima Pacheco, 2003], but there have been no reports on the effects of tritium (beta radiation) on conducting polymers, such as polyaniline or polythiophene. The direct implementation of conducting polymers as radiation sensor materials has not yet been commercialized due to differing responses with total dose, dose rate, etc. Some have reported a large increase in the surface conductivity with radiation dose while others report a marked decrease in conductive properties; these differing observations may reflect the competing mechanisms of chain scission and cross-linking. However, it is clear that the radiation dose effects on conducting polymers must be fully understood before these materials c

Kane, M.; Clark, E.; Lascola, R.

2009-12-16

155

Microwave assisted click chemistry on a conductive polymer film  

DEFF Research Database (Denmark)

Microwave (MW) irradiation has been used to accelerate the functionalization of an azide functional poly(3,4-ethylenedioxythiophene) film by click chemistry. The absorption of MW energy by the conductive polymer has been exploited for localized activation of the reaction on the polymer surface. By use of an alkyne modified fluorescein derivative the reaction conditions have been optimized in a conventional MW oven, enabling the use of different sizes of substrates. The optimization resulted in a reduction of reaction times of approximately 20h to only 2min for bulk film functionalization. The method has been applied for anchoring of the chelating agent nitrilotriacetic acid (NTA) on the conductive polymer. The chelating linkage ability of NTA on the surface was investigated through a sandwich ELISA study confirming the selective bonding of a histidine tagged protein.

Daugaard, Anders Egede; Hansen, Thomas S.

2011-01-01

156

Robust solid polymer electrolyte for conducting IPN actuators  

Science.gov (United States)

Interpenetrating polymer networks (IPNs) based on nitrile butadiene rubber (NBR) as first component and poly(ethylene oxide) (PEO) as second component were synthesized and used as a solid polymer electrolyte film in the design of a mechanically robust conducting IPN actuator. IPN mechanical properties and morphologies were mainly investigated by dynamic mechanical analysis and transmission electron microscopy. For 1-ethyl-3-methylimidazolium bis-(trifluoromethylsulfonyl)-imide (EMITFSI) swollen IPNs, conductivity values are close to 1 × 10-3 S cm-1 at 25?° C. Conducting IPN actuators have been synthesized by chemical polymerization of 3,4-ethylenedioxythiophene (EDOT) within the PEO/NBR IPN. A pseudo-trilayer configuration has been obtained with PEO/NBR IPN sandwiched between two interpenetrated PEDOT electrodes. The robust conducting IPN actuators showed a free strain of 2.4% and a blocking force of 30 mN for a low applied potential of ±2 V.

Festin, Nicolas; Maziz, Ali; Plesse, Cédric; Teyssié, Dominique; Chevrot, Claude; Vidal, Frédéric

2013-10-01

157

Direct measurement of ion mobility in a conducting polymer.  

UK PubMed Central (United Kingdom)

Using planar junctions between the conducting polymer PEDOT:PSS and various electrolytes, it is possible to inject common ions and directly observe their transit through the film. The 1D geometry of the experiment allows a straightforward estimate of the ion drift mobilities.

Stavrinidou E; Leleux P; Rajaona H; Khodagholy D; Rivnay J; Lindau M; Sanaur S; Malliaras GG

2013-08-01

158

Investigations on ferrofluid-conducting polymer composite and its application  

Energy Technology Data Exchange (ETDEWEB)

The study describes the synthesis and characterization of ferrofluid-conducting polymer composite materials and its thin films. The results of our measurement for the film grown under the influence of with and without magnetic field are quite interesting and encouraging for the electromagnetic interference shielding purpose. Change in the physical properties were correlated by analyzing the spectral features of the films.

Pant, R.P. E-mail: rppant@csnpl.ren.nic.in; Dhawan, S.K.; Kataria, N.D.; Suri, D.K

2002-11-01

159

Spectra of graphs and semi-conducting polymers  

CERN Multimedia

We study the band gap in some semi-conducting polymers with two models: H\\"uckel molecular orbital theory and the so-called free electron model. The two models are directly related to spectral theory on combinatorial and metric graphs.

Schapotschnikow, Philipp

2007-01-01

160

Direct measurement of ion mobility in a conducting polymer.  

Science.gov (United States)

Using planar junctions between the conducting polymer PEDOT:PSS and various electrolytes, it is possible to inject common ions and directly observe their transit through the film. The 1D geometry of the experiment allows a straightforward estimate of the ion drift mobilities. PMID:23784809

Stavrinidou, Eleni; Leleux, Pierre; Rajaona, Harizo; Khodagholy, Dion; Rivnay, Jonathan; Lindau, Manfred; Sanaur, Sébastien; Malliaras, George G

2013-06-20

 
 
 
 
161

All-solid-state batteries based on conducting polymers  

Energy Technology Data Exchange (ETDEWEB)

An all-solid-state battery, assembled by pressing a conducting polymer, obtained by anodic oxidation of (1)benzothieno(3,2-b)indole (TNI), between a noble element (Au,Pt) and an oxidizable metal (Zn,Mg) electrode, is presented and an operation mechanism suggested and discussed. (orig.).

Casalbore-Miceli, G.; Giro, G.; Beggiato, G.; Di Marco, P.G.; Geri, A. (Ist. di Fotochimica e Radiozioni d' Alta Energia (FRAE) del Consiglio Nazionale delle Ricerche (CNR), Bologna (Italy))

1991-05-06

162

Easy-to-fabricate conducting polymer microelectrode arrays.  

Science.gov (United States)

A simple and versatile fabrication process is used to define conducting polymer microelectrode arrays (MEAs), patterning at the same time the recording electrodes as well as the insulating layer. Thanks to the low impedance of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) electrodes, these MEAs allow in vitro recording of action potentials from rat hippocampus slices. PMID:23417987

Sessolo, Michele; Khodagholy, Dion; Rivnay, Jonathan; Maddalena, Fabien; Gleyzes, Melanie; Steidl, Esther; Buisson, Bruno; Malliaras, George G

2013-02-18

163

Antistatic and electrically conductive polymers and moulding compositions.  

UK PubMed Central (United Kingdom)

The reaction of electron acceptors, such as, for example, chlorine, bromine and/or iodine with compositions containing a linear, branched or structurally crosslinked polymer and a substituted or unsubstituted tetrathio-, tetraseleno- or tetratelluronaphthalene or -tetracene gives the compositions electric conductivity as a result of the formation of charge-transfer complexes. These compositions are suitable for producing antistatically finished or electrically conductive moulded articles, films, filaments, fibres, coatings and composites.

FINTER JURGEN DR; HILTI BRUNO DR; MAYER CARL W. DR; MINDER ERNST; PFEIFFER JOSEF DR; FINTER JUERGEN

164

Charge transfer assisted nonlinear optical and photoconductive properties of CdS-AgInS2 nanocrystals grown in semiconducting polymers  

Science.gov (United States)

Anisotropic CdS-AgInS2 nanocrystals are directly grown into benzothiadiazole-based semiconducting polymer solution. Their nonlinear optical absorption and nonlinear scattering are investigated with 7-ns laser pulses of 532-nm wavelength for optical limiting applications. Optical limiting is found to be enhanced in the polymer-CdS-AgInS2 nanocomposites, as compared to pure polymer or CdS-AgInS2 nanocrystals. The observation is explained quantitatively using a numerical model which includes one-photon-induced excited state absorption, two-photon absorption, and nonlinear scattering. Presence of charge transfer in polymer-CdS-AgInS2 nanocomposites is found from zero-biased photoconduction experiments, which plays an important role in the enhancement of nonlinear optical properties. In addition, it is also demonstrated that these nanocomposite films can be utilized for photodetection with large and fast photoconductive responses.

Mamidala, Venkatesh; Nalla, Venkatram; Sankar Maiti, Pradipta; Valiyaveettil, Suresh; Ji, Wei

2013-03-01

165

Ion-conducting polymers Quenched to dynamic disorder  

CERN Multimedia

Ion conducting polymers have a biphasic character with crystalline as well as amorphous phases. There is moreover, a dynamic disorder due to motion of polymer chain segments. The PEO-NH$_4$ClO$_4$ system undergoes a crossover from a DLA-type morphology for low salt fraction (X) to a structure with polygonal spherulites. In the present communication we show that the low X regime exhibits a variation of diffusivity with crystallinity typical of a quenched system, whereas the high X regime has dynamic disorder with rapid rearrangement.

Mandal, S S; Bhattacharya, A J; Mandal, Sarmishtha; Bhattacharyya, Aninda Jiban

1999-01-01

166

Chemiresistors based on conducting polymers: a review on measurement techniques.  

UK PubMed Central (United Kingdom)

This review covers the development of measurement configurations for chemiresistors based on conducting polymers. The simplest chemiresistors are based on application of a two-electrode technique. Artifacts caused by contact resistance can be overcome by application of a four-electrode technique. Simultaneous application of the two- and four-electrode measurement configurations provides an internal control of sensor integrity. An incorporation of two additional electrodes controlling the redox state of chemosensitive polymers and connecting to the measurement electrodes through liquid or (quasi)solid electrolyte results in a six-electrode technique; an electrically driven regeneration of such sensors allows one to perform fast and completely reversible measurements.

Lange U; Mirsky VM

2011-02-01

167

Electrically conducting fibers made from ridig rod polymers  

Energy Technology Data Exchange (ETDEWEB)

New multifunctional polymer fibers and films having high electrical conductivity plus high strength and stiffness have been prepared by several novel techniques. The resulting fibers may have strengths up to 0.5 GPa and room temperature conductivities up to 3 S/sec. All have a matrix of a rigid-rod polymer, and all have a synthetic metal phase dispersed throughout them. Host polymers are poly(p-phenylene terephthalamide) (PPTA), which is essentially DuPont's Kevlar, or poly(p-phenylene benzobisthiazole) (PBZT), and guest synthetic metals are oxidized phthalocyanines. Key to this work has been our ability to exercize specific control over microstructure, which, in turn, determines what will be the final physical properties. This control has been achieved by proper use of known (or estimated) phase relationships and predicted phase transformation kinetics. In some cases the guest species undergoes phase separation during the solidification process itself; in other cases a microstructure is established firstly with the host polymer and then the synthetic metal phase is caused to form inside it. Quantitative modelling of conductivity-composition or strength-composition relationships have been successfully accomplished, based in part on careful charge transport and thermopower measurements. (orig.).

Romanko, W.R.; McHatton, P.A.; Marcy, H.O.; Kannewurf, C.R.; Marks, T.J.; Carr, S.H. (Materials Resarch Center, Northwestern Univ., Evanston, IL (USA))

1991-05-06

168

Ultrafast terahertz conductivity and transient optical absorption spectroscopy of silicon nanocrystal thin films  

DEFF Research Database (Denmark)

We use time-resolved THz spectroscopy and transient optical absorption spectroscopy as two complementary techniques to study ultrafast carrier dynamics in silicon nanocrystal thin films. We find that the photoconductive dynamics in these materials is dominated by interface trapping, and we observe several different relaxation mechanisms for photoexcited carriers

Titova, Lyubov V.; Harthy, Rahma Al

169

Conducting Polymer Nanowire Arrays for High Performance Supercapacitors.  

UK PubMed Central (United Kingdom)

This Review provides a brief summary of the most recent research developments in the fabrication and application of one-dimensional ordered conducting polymers nanostructure (especially nanowire arrays) and their composites as electrodes for supercapacitors. By controlling the nucleation and growth process of polymerization, aligned conducting polymer nanowire arrays and their composites with nano-carbon materials can be prepared by employing in situ chemical polymerization or electrochemical polymerization without a template. This kind of nanostructure (such as polypyrrole and polyaniline nanowire arrays) possesses high capacitance, superior rate capability ascribed to large electrochemical surface, and an optimal ion diffusion path in the ordered nanowire structure, which is proved to be an ideal electrode material for high performance supercapacitors. Furthermore, flexible, micro-scale, threadlike, and multifunctional supercapacitors are introduced based on conducting polyaniline nanowire arrays and their composites. These prototypes of supercapacitors utilize the high flexibility, good processability, and large capacitance of conducting polymers, which efficiently extend the usage of supercapacitors in various situations, and even for a complicated integration system of different electronic devices.

Wang K; Wu H; Meng Y; Wei Z

2013-08-01

170

Surface modification of the conducting polymer, polypyrrole, via affinity peptide.  

Science.gov (United States)

A novel strategy for affinity-based surface modification of the conducting polymer, polypyrrole, (PPy), has been developed. A 12-amino acid peptide (THRTSTLDYFVI, hereafter denoted T59) was previously identified via the phage display technique. This peptide noncovalently binds to the chlorine-doped conducting polymer polypyrrole (PPyCl). Studies have previously shown that conductive polymers have promising application in neural electrodes, sensors, and for improving regeneration and healing of peripheral nerves and other tissues. Thus, the strong and specific attachment of bioactive molecules to the surface of PPy using the T59 affinity peptide is an exciting new approach to enhance the bioactivity of electrically active materials for various biomedical applications. We demonstrate this by using T59 as a tether to modify PPyCl with the laminin fragment IKVAV to enhance cell interactions, as well as with the so-called stealth molecule poly(ethylene glycol; PEG) to decrease cell interactions. Using these two modification strategies, we were able to control cell attachment and neurite extension on the PPy surface, which is critical for different applications (i.e., the goal for tissue regeneration is to enhance cell interactions, whereas the goal for electrode and sensor applications is to reduce glial cell interactions and thus decrease scarring). Significantly, the conductivity of the PPyCl surface was unaffected by this surface modification technique, which is not the case with other methods that have been explored to surface modify conducting polymers. Finally, using subcutaneous implants, we confirmed that the PPyCl treated with the T59 peptide did not react in vivo differently than untreated PPyCl. PMID:23129217

Nickels, Jonathan D; Schmidt, Christine E

2012-11-05

171

Surface modification of the conducting polymer, polypyrrole, via affinity peptide.  

UK PubMed Central (United Kingdom)

A novel strategy for affinity-based surface modification of the conducting polymer, polypyrrole, (PPy), has been developed. A 12-amino acid peptide (THRTSTLDYFVI, hereafter denoted T59) was previously identified via the phage display technique. This peptide noncovalently binds to the chlorine-doped conducting polymer polypyrrole (PPyCl). Studies have previously shown that conductive polymers have promising application in neural electrodes, sensors, and for improving regeneration and healing of peripheral nerves and other tissues. Thus, the strong and specific attachment of bioactive molecules to the surface of PPy using the T59 affinity peptide is an exciting new approach to enhance the bioactivity of electrically active materials for various biomedical applications. We demonstrate this by using T59 as a tether to modify PPyCl with the laminin fragment IKVAV to enhance cell interactions, as well as with the so-called stealth molecule poly(ethylene glycol; PEG) to decrease cell interactions. Using these two modification strategies, we were able to control cell attachment and neurite extension on the PPy surface, which is critical for different applications (i.e., the goal for tissue regeneration is to enhance cell interactions, whereas the goal for electrode and sensor applications is to reduce glial cell interactions and thus decrease scarring). Significantly, the conductivity of the PPyCl surface was unaffected by this surface modification technique, which is not the case with other methods that have been explored to surface modify conducting polymers. Finally, using subcutaneous implants, we confirmed that the PPyCl treated with the T59 peptide did not react in vivo differently than untreated PPyCl.

Nickels JD; Schmidt CE

2013-05-01

172

Effect of substrate temperature on conductivity and microstructures of boron-doped silicon nanocrystals in SiCx thin films  

Science.gov (United States)

Boron (B)-doped silicon-rich SiC (SiCx, 0conductivity and microstructures of the annealed B-doped SiCx thin films were studied. The crystalline fraction increased by 5%, while the conductivity increased by 10-100 times, in the annealed thin films deposited at about 200 °C, comparing to that deposited at RT -400 °C. The face-centered cubic (fcc) Si nanocrystals (Si-NCs) formed in the surface layer when Ts was about 200 °C. It was suggested that Ts influenced the crystallization, conductivity and even the microstructures of Si-NCs. The proper Ts was helpful to improve the crystallization and conductivity of the B-doped Si-NCs in SiCx thin film.

Cheng, Qiang; Zeng, Yuheng; Huang, Junjun; Dai, Ning; Yang, Ye; Tan, Ruiqin; Liang, Xingbo; Song, Weijie

2013-09-01

173

Microwrinkled conducting polymer interface for anisotropic multicellular alignment.  

UK PubMed Central (United Kingdom)

Surfaces with controlled micro and nanoscale topographical cues are useful as smart scaffolds and biointerfaces for cell culture. Recently, use of thin-film and surface wrinkling is emerging as a rapid unconventional method for preparing topographically patterned surfaces, especially suited for the production of smart patterns over large area surfaces. On the other hand, there is an increasing interest in employing conducting polymers as soft, biocompatible, conductive biointerfaces or as parts of bioelectronic devices. A novel convenient and versatile method is presented for producing anisotropic topographical cues at the micro- and nanoscale on conducting polymer surfaces. Micro and nanowrinkles were formed during the heat-shrinking process of a thermo-retractable polystyrene substrate. Surface wrinkling was due to the mismatch between the mechanical properties of a conducting polymer ultrathin film and the substrate. Various geometries of wrinkled structures were prepared, demonstrating the tunability of topography depending on the thickness of the conductive film. A method for patterning the conductive properties of the wrinkled substrates was also presented. Such surfaces acted as smart scaffolds for the functional alignment of cells, envisioning their electrical stimulation. Cell adhesion and proliferation were evaluated, comparing different topographies, and a preferential anisotropic alignment of C2C12 murine skeletal muscle cells along wrinkles was demonstrated. The observed trends were also confirmed concerning the formation of aligned myotubes in C2C12 differentiation stage. Furthermore, improved results in terms of aligned and mature myotube formation were obtained by co-culturing C2C12 cells with a fibroblasts feeder layer. The combination of living cells and tunable conductive nanowrinkles will represent a unique tool for the development of innovative biomedical devices.

Greco F; Fujie T; Ricotti L; Taccola S; Mazzolai B; Mattoli V

2013-02-01

174

Effective medium theory of conduction in stretched polymer electrolytes  

CERN Multimedia

Recent experimental observations of anisotropic conductivity in stretched polymer electrolytes films of the polyethylene oxide family are discussed. The main experimental observations, enhancement of the ionic diffusion and conductivity in the stretch direction and decrease in these transport coefficients in the normal direction are interpreted in terms of an effective two-phase model. This two-phase model is based on the idea that a highly conducting phase is associated with oriented molecular structures which are surrounded by poorly conducting boundary regions. This model is evaluated within the framework of differential effective medium theory (DEMT). Under stretching these regions change from spherical to prolate-spheroidal shapes. The computed dependence of the DC conductivity tensor and its AC counterpart on the stretch parameters is in good agreement with experimental results.

Dürr, O; Maas, P; Nitzan, A; Duerr, Oliver; Dieterich, Wolfgang; Maas, Philipp; Nitzan, Abraham

2002-01-01

175

Spin dynamics in conducting polymers studied by {mu}SR  

Energy Technology Data Exchange (ETDEWEB)

We report studies of spin dynamics in the conducting polymers polyaniline and polypyrrole using both {mu}{sup +}SR and {mu}{sup -}SR techniques. These measurements reveal characteristic field dependences and cutoff frequencies for the muon spin relaxation which can be related to the spin diffusion process. Clear evidence is seen for increased spin localisation at low temperatures where a crossover occurs from two or three dimensional spin diffusion to a one dimensional diffusion regime.

Pratt, F.L. [Institute of Physical and Chemical Research (RIKEN), Rutherford Appleton Laboratory, Muon Science Laboratory (United Kingdom); Blundell, S.J.; Pattenden, P.A.; Hayes, W.; Chow, K.H. [University of Oxford, Clarendon Laboratory, Department of Physics (United Kingdom); Monkman, A.P. [University of Durham, Department of Physics (United Kingdom); Ishiguro, T. [Kyoto University, Department of Physics (Japan); Ishida, K.; Nagamine, K. [Institute of Physical and Chemical Research (RIKEN), Rutherford Appleton Laboratory, Muon Science Laboratory (United Kingdom)

1997-04-15

176

Spin dynamics in conducting polymers studied by ?SR  

International Nuclear Information System (INIS)

We report studies of spin dynamics in the conducting polymers polyaniline and polypyrrole using both ?+SR and ?-SR techniques. These measurements reveal characteristic field dependences and cutoff frequencies for the muon spin relaxation which can be related to the spin diffusion process. Clear evidence is seen for increased spin localisation at low temperatures where a crossover occurs from two or three dimensional spin diffusion to a one dimensional diffusion regime

1997-01-01

177

Pedot and PPy Conducting Polymer Bilayer and Trilayer Actuators  

DEFF Research Database (Denmark)

Actuators based on conducting polymers are attracting increasing interest due to their desirable features such as large mechanical stress generated, sufficient maximum strain values, high reversibility, good safety properties and the possibility of precise control using small voltages. Many attempts have been made to improve the actuator performance. We report electromechanical measurements on actuators of bilayer and trilayer free standing films prepared with polypyrrole (PPy) and poly(3,4-ethylenedioxythiophene) (PEDOT) conducting polymers. Both types of conducting polymer are pre-doped during synthesis with dodecyl benzenesulfonate (DBS). These multilayer films were prepared electrochemically so that the PEDOT layer is very thin compared to that of the PPy layer. In the trilayer film, the PEDOT layer is sandwiched between two PPy layers.The films were characterized electromechanically and the results compared with those of PPy single layer film. Bilayer films show a significant increase in the strain measured at higher scan rates (>100mVs?1). The force difference generated between the reduced and oxidized states is much higher for trilayer films and higher for bilayer films than that in a single layer of PPy. Trilayer films are both stronger and faster than a single layer PPy film of half the thickness.

Zainudeen, Umer Lebbe; Careem, Mohamed Abdul

2008-01-01

178

Functional Conducting Polymers via Thiol-ene Chemistry  

Directory of Open Access Journals (Sweden)

Full Text Available We demonstrate here that thiol-ene chemistry can be used to provide side-chain functionalized monomers based on 3,4-propylenedioxythiophene (ProDOT) containing ionic, neutral, hydrophobic, and hydrophilic side chains. All reactions gave high yields and purification could generally be accomplished through precipitation. These monomers were polymerized either chemically or electro-chemically to give soluble materials or conductive films, respectively. This strategy provides for facile tuning of the solubility, film surface chemistry, and film morphology of this class of conducting polymers.

Kathleen E. Feldman; David C. Martin

2012-01-01

179

New transparent conductive metal based on polymer composite  

Energy Technology Data Exchange (ETDEWEB)

Currently great efforts are made to develop new kind of transparent conductors (TCs) to replace ITO. In this regard different materials and composites have been proposed and studied including conductive polymers, carbon nanotubes (CNTs), metal grids, and random networks of metallic nanowires. But so far none of them could be used as a replacing material, since either they are either fragile and brittle or their electrical conductivity is below the typical ITO. Thin metallic films due to their high electrical conductivity could be one of the best replacing materials for ITO, however their poor transparency makes their application as TCs limited. Here we design and fabricate a new polymeric composite coating which enhances the transparency of the thin metal film up to 100% relative to the initial value while having a high electrical conductivity of typical metals. Therefore our proposed device has a great potential to be used as new transparent conductor.

Keshavarz Hedayati, Mehdi; Jamali, Mohammad [Nanochemistry and Nanoengineering, Institute for Materials Science, Faculty of Engineering, Christian-Albrechts-University, Kiel (Germany); Strunkus, Thomas; Zaporochentko, Vladimir; Faupel, Franz [Multicomponent Materials, Institute for Materials Science, Faculty of Engineering, Christian-Albrechts-University, Kiel (Germany); Elbahri, Mady [Nanochemistry and Nanoengineering, Institute for Materials Science, Faculty of Engineering, Christian-Albrechts-University, Kiel (Germany); Helmholtz-Zentrum Geesthacht GmbH, Institute of Polymer Research, Nanochemistry and Nanoengineering (Germany)

2011-07-01

180

Conductivity of oriented bis-azo polymer films  

DEFF Research Database (Denmark)

The conductivity properties of electro-optic photoaddressable, dense bis-ozo chromophore polymer films are investigated by using samples corona poled at various temperatures. A dielectric spectrometer is applied to measure the frequency dependence of the conductivity at different temperatures before and after heating the material to above the glass transition temperature. The results show that the orientation of the chromophores changes the charge-carrier mobility. Ionic conductivity dominates in a more disordered configuration of the material, while the competing process of hole hopping takes over as a transition to a liquid-crystalline phase occurs when the material is heated to much higher than the gloss transition temperature. Such micro-crystallization strongly enhances the conductivity.

Apitz, D.; Bertram, R.P.

2006-01-01

 
 
 
 
181

Ion Conductivity and Transport by Porous Coordination Polymers and Metal-Organic Frameworks.  

UK PubMed Central (United Kingdom)

Ion conduction and transport in solids are both interesting and useful and are found in widely distinct materials, from those in battery-related technologies to those in biological systems. Scientists have approached the synthesis of ion-conductive compounds in a variety of ways, in the areas of organic and inorganic chemistry. Recently, based on their ion-conducting behavior, porous coordination polymers (PCPs) and metal-organic frameworks (MOFs) have been recognized for their easy design and the dynamic behavior of the ionic components in the structures. These PCP/MOFs consist of metal ions (or clusters) and organic ligands structured via coordination bonds. They could have highly concentrated mobile ions with dynamic behavior, and their characteristics have inspired the design of a new class of ion conductors and transporters. In this Account, we describe the state-of-the-art of studies of ion conductivity by PCP/MOFs and nonporous coordination polymers (CPs) and offer future perspectives. PCP/MOF structures tend to have high hydrophilicity and guest-accessible voids, and scientists have reported many water-mediated proton (H(+)) conductivities. Chemical modification of organic ligands can change the hydrated H(+) conductivity over a wide range. On the other hand, the designable structures also permit water-free (anhydrous) H(+) conductivity. The incorporation of protic guests such as imidazole and 1,2,4-triazole into the microchannels of PCP/MOFs promotes the dynamic motion of guest molecules, resulting in high H(+) conduction without water. Not only the host-guest systems, but the embedding of protic organic groups on CPs also results in inherent H(+) conductivity. We have observed high H(+) conductivities under anhydrous conditions and in the intermediate temperature region of organic and inorganic conductors. The keys to successful construction are highly mobile ionic species and appropriate intervals of ion-hopping sites in the structures. Lithium (Li(+)) and other ions can also be transported. If we can optimize the crystal structures, this could offer further improvements in terms of both conductivity and the working temperature range. Another useful characteristic of PCP/MOFs is their wide application to materials fabrication. We can easily prepare heterodomain crystal systems, such as core-shell or solid solution. Other anisotropic morphologies (thin film, nanocrystal, nanorod, etc.,) are also possible, with retention of the ion conductivity. The flexible nature also lets us design morphology-dependent ion-conduction behaviors that we cannot observe in the bulk state. We propose (1) multivalent ion and anion conductions with the aid of redox activity and defects in structures, (2) control of ion transport behavior by applying external stimuli, (3) anomalous conductivity at the hetero-solid-solid interface, and (4) unidirectional ion transport as in the ion channels in membrane proteins. In the future, scientists may use coordination polymers not only to achieve higher conductivity but also to control ion behavior, which will open new avenues in solid-state ionics.

Horike S; Umeyama D; Kitagawa S

2013-06-01

182

Self-assembly of CdTe nanocrystals at the water/oil interface by amphiphilic hyperbranched polymers  

International Nuclear Information System (INIS)

[en] A general strategy for realizing the self-assembly of aqueous CdTe nanocrystals (NCs) at the water/oil interface by means of an amphiphilic core-shell hyperbranched polymer has been proposed. Aqueous CdTe NCs were firstly transferred into the chloroform phase in the presence of palmityl chloride functionalized hyperbranched poly(amidoamine) (HPAMAM-PC), and then self-assembled at the water/chloroform interface by decreasing the pH value of the aqueous phase or introducing ?-CDs to the aqueous phase. The resulting CdTe/HPAMAM-PC self-assembly film was characterized by fluorescence microscopy, UV-vis, PL, TEM, EDS, FT-IR, DSC and TGA.

2008-11-05

183

Electroluminescence of a single active layer polymer-nanocrystal hybrid light-emitting diode with inversion symmetry  

International Nuclear Information System (INIS)

A hybrid polymer-nanocrystal (NC) light-emitting diode (LED) device with a single active layer structure is simply fabricated by a spin coating. From a high-resolution transmission electron microscopy (HRTEM) study, each PVK polymer particle is observed to be capped with TPBi molecules and CdSe/ZnS NCs are mainly distributed along the circumference of PVK and TPBi surfaces, resulting in a core-shell polymer-NC hybrid of [CdSe/ZnS]/TPBi/[CdSe/ZnS]/PVK. An Al/[CdSe/ZnS]/TPBi/[CdSe/ZnS]/PVK/indium-tin oxide(ITO)/glass LED shows electroluminescence (EL) centered at around 585 nm at the forward bias of +10 V, which clearly reveals that CdSe/ZnS NCs existing at the interface between PVK and TPBi act as recombination centers for excitons. In particular, EL can be observed at both forward bias and reverse bias, and this means that this device with an isotropic distribution of NCs has an inversion symmetry.

2009-07-08

184

Cellulose nanocrystals vs. cellulose nanofibrils: a comparative study on their microstructures and effects as polymer reinforcing agents.  

UK PubMed Central (United Kingdom)

Both cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs) are nanoscale cellulose fibers that have shown reinforcing effects in polymer nanocomposites. CNCs and CNFs are different in shape, size and composition. This study systematically compared their morphologies, crystalline structure, dispersion properties in polyethylene oxide (PEO) matrix, interactions with matrix, and the resulting reinforcing effects on the matrix polymer. Transparent PEO/CNC and PEO/CNF nanocomposites comprising up to 10 wt % nanofibers were obtained via solution casting. Scanning electron microscopy (SEM), wide-angle X-ray diffraction (WXRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), dynamic mechanical analyzer (DMA), and tensile testing were used to examine the above-mentioned properties of nanocellulose fibers and composites. At the same nanocellulose concentration, CNFs led to higher strength and modulus than did CNCs due to CNFs' larger aspect ratio and fiber entanglement, but lower strain-at-failure because of their relatively large fiber agglomerates. The Halpin-Kardos and Ouali models were used to simulate the modulus of the composites and good agreements were found between the predicted and experimental values. This type of systematic comparative study can help to develop the criteria for selecting proper nanocellulose as a biobased nano-reinforcement material in polymer nanocomposites.

Xu X; Liu F; Jiang L; Zhu JY; Haagenson D; Wiesenborn DP

2013-04-01

185

Nanocrystal doped matrixes  

Energy Technology Data Exchange (ETDEWEB)

Matrixes doped with semiconductor nanocrystals are provided. In certain embodiments, the semiconductor nanocrystals have a size and composition such that they absorb or emit light at particular wavelengths. The nanocrystals can comprise ligands that allow for mixing with various matrix materials, including polymers, such that a minimal portion of light is scattered by the matrixes. The matrixes of the present invention can also be utilized in refractive index matching applications. In other embodiments, semiconductor nanocrystals are embedded within matrixes to form a nanocrystal density gradient, thereby creating an effective refractive index gradient. The matrixes of the present invention can also be used as filters and antireflective coatings on optical devices and as down-converting layers. Processes for producing matrixes comprising semiconductor nanocrystals are also provided. Nanostructures having high quantum efficiency, small size, and/or a narrow size distribution are also described, as are methods of producing indium phosphide nanostructures and core-shell nanostructures with Group II-VI shells.

Parce, J. Wallace (Palo Alto, CA); Bernatis, Paul (Sunnyvale, CA); Dubrow, Robert (San Carlos, CA); Freeman, William P. (San Mateo, CA); Gamoras, Joel (Vallejo, CA); Kan, Shihai (San Jose, CA); Meisel, Andreas (Redwood City, CA); Qian, Baixin (Sunnyvale, CA); Whiteford, Jeffery A. (Belmont, CA); Ziebarth, Jonathan (Palo Alto, CA)

2010-01-12

186

Intrinsic electrical conductivity of nanostructured metal-organic polymer chains  

Science.gov (United States)

One-dimensional conductive polymers are attractive materials because of their potential in flexible and transparent electronics. Despite years of research, on the macro- and nano-scale, structural disorder represents the major hurdle in achieving high conductivities. Here we report measurements of highly ordered metal-organic nanoribbons, whose intrinsic (defect-free) conductivity is found to be 104?S?m?1, three orders of magnitude higher than that of our macroscopic crystals. This magnitude is preserved for distances as large as 300?nm. Above this length, the presence of structural defects (~ 0.5%) gives rise to an inter-fibre-mediated charge transport similar to that of macroscopic crystals. We provide the first direct experimental evidence of the gapless electronic structure predicted for these compounds. Our results postulate metal-organic molecular wires as good metallic interconnectors in nanodevices.

Hermosa, Cristina; Vicente Alvarez, Jose; Azani, Mohammad-Reza; Gomez-Garcia, Carlos J.; Fritz, Michelle; Soler, Jose M.; Gomez-Herrero, Julio; Gomez-Navarro, Cristina; Zamora, Felix

2013-01-01

187

Intrinsic electrical conductivity of nanostructured metal-organic polymer chains.  

UK PubMed Central (United Kingdom)

One-dimensional conductive polymers are attractive materials because of their potential in flexible and transparent electronics. Despite years of research, on the macro- and nano-scale, structural disorder represents the major hurdle in achieving high conductivities. Here we report measurements of highly ordered metal-organic nanoribbons, whose intrinsic (defect-free) conductivity is found to be 10(4) S m(-1), three orders of magnitude higher than that of our macroscopic crystals. This magnitude is preserved for distances as large as 300 nm. Above this length, the presence of structural defects (~ 0.5%) gives rise to an inter-fibre-mediated charge transport similar to that of macroscopic crystals. We provide the first direct experimental evidence of the gapless electronic structure predicted for these compounds. Our results postulate metal-organic molecular wires as good metallic interconnectors in nanodevices.

Hermosa C; Vicente Álvarez J; Azani MR; Gómez-García CJ; Fritz M; Soler JM; Gómez-Herrero J; Gómez-Navarro C; Zamora F

2013-01-01

188

High-throughput screening of ionic conductivity in polymer membranes  

International Nuclear Information System (INIS)

[en] Combinatorial and high-throughput techniques have been successfully used for efficient and rapid property screening in multiple fields. The use of these techniques can be an advantageous new approach to assay ionic conductivity and accelerate the development of novel materials in research areas such as fuel cells. A high-throughput ionic conductivity (HTC) apparatus is described and applied to screening candidate polymer electrolyte membranes for fuel cell applications. The device uses a miniature four-point probe for rapid, automated point-to-point AC electrochemical impedance measurements in both liquid and humid air environments. The conductivity of Nafion 112 HTC validation standards was within 1.8% of the manufacturer's specification. HTC screening of 40 novel Kynar poly(vinylidene fluoride) (PVDF)/acrylic polyelectrolyte (PE) membranes focused on varying the Kynar type (5x) and PE composition (8x) using reduced sample sizes. Two factors were found to be significant in determining the proton conducting capacity: (1) Kynar PVDF series: membranes containing a particular Kynar PVDF type exhibited statistically identical mean conductivity as other membranes containing different Kynar PVDF types that belong to the same series or family. (2) Maximum effective amount of polyelectrolyte: increments in polyelectrolyte content from 55 wt% to 60 wt% showed no statistically significant effect in increasing conductivity. In fact, some membranes experienced a reduction in conductivity.

2009-06-01

189

Electrochemical synthesis of intrinsically conducting polymers of 3-alkylpyrroles  

Energy Technology Data Exchange (ETDEWEB)

In the present work the electrochemical polymerization of pyrrole (Py) derivatives has been performed in order to identify the conditions for obtaining intrinsically conducting polymers, checking film morphology and conductivity. The study mainly concerns 3-alkylsubstituted pyrroles with different chain lengths (3-hexylpyrrole (3HP), 3-decylpyrrole (3DP), 3-hexadecylpyrrole (3HDP)). In the case of 3DP (0.01 M) various experimental conditions have been adopted: different solvents (propylene carbonate, acetonitrile), different counterions (ClO{sub 4}{sup -}, BF{sub 4}{sup -}, NO{sub 3}{sup -}, PF{sub 6}{sup -}, TsO{sup -}) with the same cation Bu{sub 4}N{sup +} and different current densities (0.05, 0.1, 0.2, 0.4 mA cm{sup -2}) in the case of BF{sub 4}{sup -} in propylene carbonate. Porous and elastic films are obtained when the substituent alkyl side chain is longer and the supporting electrolytes are ClO{sub 4}{sup -}, BF{sub 4}{sup -}, PF{sub 6}{sup -}; with these last electrolytes the best conductivity is also obtained (0.1-0.8 S cm{sup -1} for poly(3-decylpyrrole), P3DP). P3DP(TsO) and P3DP(NO{sub 3}), aside from the type of solvent, show poor mechanical properties and low electrical conductivity (10{sup -3} and 10{sup -6} S cm{sup -1} for P3DP(TsO) and P3DP(NO{sub 3}), respectively). The conductivity decreases as the alkyl side chain becomes longer. When the polymerization is performed at low monomer concentration (of the order of 0.001 M), the surface properties of P3DP(ClO{sub 4}) are very poor and the conductivity is only 10{sup -3} S cm{sup -1}. The obtained polymers have also been electrochemically characterized through cyclic voltammetry. (orig.) 44 refs.

Costantini, N.; Cagnolati, R.; Nucci, L.; Pergola, F.; Ruggeri, G. [Pisa Univ. (Italy). Dipt. di Chimica e Chimica Industriale

1998-01-30

190

Fabrication and characterization of solid-state, conducting polymer actuators  

Energy Technology Data Exchange (ETDEWEB)

We report here the fabrication and characterization of solid-state, conducting polymer actuators. The electrochemical activity of polyaniline (PANI) thin film coated with solid-state polyelectrolyte is very similar to the polyaniline thin film in an aqueous solution. The solid-state actuator is adhere to a lever arm of an force transducer and the force generation is measured in real time. The force generated by the actuator is found to be length dependent. However, the overall torques generated by the actuators with different lengths remains essentially the same. The effect of stimulation signals such as voltage, current, on the bending angle and displacement is also studied using square wave potential.

Xie, J. (Jian); Sansinena, J. M. (Jose-Maria); Gao, J. (Junbo); Wang, H. L. (Hsing-Lin)

2004-01-01

191

Electrical conductivity of radiation-processed wood polymer composites  

International Nuclear Information System (INIS)

Two species of wood, viz. Haldu (Adina Cordifolia) and Jamun (Syzygium Cumini) were vacuum-impregnated with two styrene-based monomer systems and polymerized in situ with gamma radiation from a cobalt-60 source. The electrical conductivity of these specimens was determined at various polymer loadings under dry conditions, after wetting and after wet recovery as per ASTM standards. The water absorption characteristics are also presented. The results are discussed with special reference to the role of water. Potential applications are also discussed. 7 figures.

1978-01-01

192

Na+ Ion Conducting Hot-pressed Nano Composite Polymer Electrolytes  

Directory of Open Access Journals (Sweden)

Full Text Available Synthesis, characterization and polymeric battery studies of Na+ ion conducting Nano- Composite Polymer Electrolyte (NCPE) membranes: (1-x) [75PEO: 25NaPO3]: x SiO2, where x = 0 - 15 wt. (%), has been reported. NCPE membranes have been casted using a novel hot-press technique in place of the traditional solution cast method. The dispersal of SiO2 in SPE host: (75PEO: 25NaPO3), a conductivity enhancement of an order of magnitude achieved in NCPE film: [93 (75PEO: 25NaPO3): 7 SiO2]. This has been referred to as Optimum Conducting Composition (OCC). Material characterizations have been done with the help of XRD, SEM and DSC techniques. The ion transport behaviour in hot-pressed NCPEs has been discussed on the basis of experimental measurements on some basic ionic parameters viz. conductivity (?), ionic mobility (?), mobile ion concentration (n) and ionic transference number (t ion). The temperature dependent conductivity studies have been done to compute the activation energy (Ea) values from the 'log s - 1/T' Arrhenius plots. The ion conducting solid state polymeric battery was fabricated and cell-potential discharge characteristics have been studied at different load conditions.

Angesh Chandra; Archan Chandra; Kiran Thakurb

2012-01-01

193

Conducting polymer gel prepared by radical initiator and its characteristics  

Energy Technology Data Exchange (ETDEWEB)

Soluble poly(3-alkylthiophene) (P3AT) was converted into conducting polymer gel using a radical initiator, and its properties dependent on the degree of cross-linking were studied. Benzoyl peroxide (BPO) was used as the radical initiator, and after BPO dissolved in chloroform solvent was added dropwise to the soluble P3AT, the remaining insoluble fraction was used as specimens. The IR absorption spectrum of specimens was mostly similar to that of the original P3AT. The volume of the gel shrank drastically in ethanol solvent as compared with that in chloroform, and its shrinkage ratio was strongly dependent on BPO concentration. The color spectrum of the gel varied drastically and reversibly with volume change. By introducing iodine into chloroform solvent, the volume of the gel shrank considerably changing its color from yellow to black, and the electrical conductivity of the gel was also enhanced indicating insulator-metal transition. 17 refs., 9 figs.

Morita, S.; Kawai, T.; Yoshino, K. (Osaka University, Osaka (Japan). Faculty of Engineering)

1991-04-15

194

Conducting polymer nanowires-based label-free biosensors.  

UK PubMed Central (United Kingdom)

Label-free sensing technologies have recently attracted a great deal of interest for sensitive, rapid and facile analysis for applications in health care, environmental monitoring, food safety and homeland security. One-dimensional (1-D) nanostructures such as nanowires, configured as field-effect transistors (FETs)/chemiresistors that change conductance upon binding of charged macromolecules to receptors linked to the device surfaces are extremely attractive for label-free biosensors. Herein, we review recent advances in label-free biosensors based on conducting polymer nanowires based FET/chemiresistor. Specifically, we address the fabrication, functionalization, assembly/alignment and sensing applications of FET/chemiresistor based on these nanomaterials. The advantages and disadvantages of various fabrication, functionalization, and assembling procedures of these nanosensors are reviewed and discussed.

Mulchandani A; Myung NV

2011-08-01

195

On the Electronic Transport Mechanism in Conducting Polymer Nanofibers  

CERN Multimedia

Here, we present theoretical analysis of electron transport in polyaniline based (PANi) nanofibers assuming the metalic state of the material. To build up this theory we treat conducting polymers as a special kind of granular metals, and we apply the quantum theory of conduction in mesoscopic systems to describe the transport between metallic-like granules. Our results show that the concept of resonance electron tunneling as the predominating mechanism providing charge transport between the grains is supported with recent experiments on the electrical characterization of single PANi nanofibers. By contacting the proposed theory with the experimental data we estimate some important parameters characterizing the electron transport in these materials. Also, we discuss the origin of rectifying features observed in current-voltage characteristics of fibers with varying cross-sectional areas.

Zimbovskaya, N A; Pinto, N J; Zimbovskaya, Natalya A.; Johnson, Alan T.; Pinto, Nicholas J.

2005-01-01

196

Conductive polymer combined silk fiber bundle for bioelectrical signal recording.  

UK PubMed Central (United Kingdom)

Electrode materials for recording biomedical signals, such as electrocardiography (ECG), electroencephalography (EEG) and evoked potentials data, are expected to be soft, hydrophilic and electroconductive to minimize the stress imposed on living tissue, especially during long-term monitoring. We have developed and characterized string-shaped electrodes made from conductive polymer with silk fiber bundles (thread), which offer a new biocompatible stress free interface with living tissue in both wet and dry conditions.An electroconductive polyelectrolyte, poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) was electrochemically combined with silk thread made from natural Bombyx mori. The polymer composite 280 µm thread exhibited a conductivity of 0.00117 S/cm (which corresponds to a DC resistance of 2.62 Mohm/cm). The addition of glycerol to the PEDOT-PSS silk thread improved the conductivity to 0.102 S/cm (20.6 kohm/cm). The wettability of PEDOT-PSS was controlled with glycerol, which improved its durability in water and washing cycles. The glycerol treated PEDOT-PSS silk thread showed a tensile strength of 1000 cN in both wet and dry states. Without using any electrolytes, pastes or solutions, the thread directly collects electrical signals from living tissue and transmits them through metal cables. ECG, EEG, and sensory evoked potential (SEP) signals were recorded from experimental animals by using this thread placed on the skin. PEDOT-PSS silk glycerol composite thread offers a new class of biocompatible electrodes in the field of biomedical and health promotion that does not induce stress in the subjects.

Tsukada S; Nakashima H; Torimitsu K

2012-01-01

197

Conductivity enhancement of conjugated polymer after HCl-methanol treatment  

International Nuclear Information System (INIS)

[en] Polymer conductivity is key factor to improve the performance of the electronic and photonic devices. Poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) films were soaked into 0.03, 0.14, 0.41, and 1.13 M concentrations of HCl-methanol solution for 10, 20, 30, 40, 50, 60, and 70 min. The resulting films were investigated using Fourier transform infrared (FTIR) spectrometry, conductivity measurements, and field emission scanning electron microscopy. The characteristic FTIR absorption peaks of poly(4-styrenesulfonate) (PSS) of the films decreased as the soaking time increased. While PSS absorption peaks appeared in the HCl-methanol soaking solution and increased with the soaking time. The conductivity of PEDOT:PSS film was approximately 1.20 x 10-6 S/cm before soaking in the HCl-methanol solution. The conductivity of PEDOT:PSS was enhanced nearly three orders of magnitude after soaking the films into the HCl-methanol solvent. The surface of PEDOT:PSS film was initially very smooth. However, numerous humps appeared on the surface of the films after soaking PEDOT:PSS film into the HCl-methanol solution for 10, 20, and 30 min. The number of humps was reduced and disappeared thereafter.

2009-08-31

198

Analysis of surface modified polymers: XPS and conductivity measurements  

Energy Technology Data Exchange (ETDEWEB)

Full text: Design specific, surface modified polymers are finding ever increasing application in technological, manufacturing and medical areas. A brief review will be presented of such, followed by specific reference to electrical properties of surface modified polymeric materials, their application and analysis. A new method has been devised for the measurement of resistivity in the surface region of insulating materials, including many well known polymers. It measures resistivity through recording of the decay of surface charge placed on the surface of a sample. This method will be outlined and results presented. An ionic charge transport theory has also been developed, based on self field driven motion of, and diffusion transport of, charge carriers; which provides greater insight into the way carriers move in the surface region of insulators in general. The agreement between this theory and the measurements obtained has resulted in an accurate technique for the measurement of electrical resistivity in the surface region of insulators. Values may also be simultaneously obtained for the carrier diffusion coefficient, and the carrier occupancy depth. The methodology has been applied to a series of surface modified polymers under various grafting conditions (graft concentration, temperature and time). The chosen substrates were: polyaniline (PAN), low density polyethylene (LDPE) and teflon (PTFE), pretreated for grafting by either Ar plasma or ozone. The graft monomers used for copolymerisation were acrylic acid (Mc), sodium salt of styrene sulfonic acid (NaSS) and N,N-dimethylacrylamide (DMAA). XPS measurements of the samples will also be used to infer the conduction mechanisms in the materials resulting from grafting procedures. Copyright (1999) Australian X-ray Analytical Association Inc.

Liesegang, J. [La Trobe University, Bundoora, VIC (Australia). Department of Physics and Centre for Materials and Surface Science

1999-12-01

199

Conductive paper from lignocellulose wood microfibers coated with a nanocomposite of carbon nanotubes and conductive polymers  

International Nuclear Information System (INIS)

Composite nanocoating of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) and aqueous dispersion of carbon nanotubes (CNT-PSS) on lignocellulose wood microfibers has been developed to make conductive microfibers and paper sheets. To construct the multilayers on wood microfibers, cationic poly(ethyleneimine) (PEI) has been used in alternate deposition with anionic conductive PEDOT-PSS and solubilized CNT-PSS. Using a Keithley microprobe measurement system, current-voltage measurements have been carried out on single composite microfibers after deposition of each layer to optimize the electrical properties of the coated microfibers. The conductivity of the resultant wood microfibers was in the range of 10-2-2 S cm-1 depending on the architecture of the coated layer. Further, the conductivity of the coated wood microfibers increased up to 20 S cm-1 by sandwiching multilayers of conductive co-polymer PEDOT-PSS with CNT-PSS through a polycation (PEI) interlayer. Moreover, paper hand sheets were manufactured from these coated wood microfibers with conductivity ranging from 1 to 20 S cm-1. A paper composite structure consisting of conductive/dielectric/conductive layers that acts as a capacitor has also been fabricated and is reported.

2009-05-27

200

Conductive paper from lignocellulose wood microfibers coated with a nanocomposite of carbon nanotubes and conductive polymers  

Science.gov (United States)

Composite nanocoating of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) and aqueous dispersion of carbon nanotubes (CNT-PSS) on lignocellulose wood microfibers has been developed to make conductive microfibers and paper sheets. To construct the multilayers on wood microfibers, cationic poly(ethyleneimine) (PEI) has been used in alternate deposition with anionic conductive PEDOT-PSS and solubilized CNT-PSS. Using a Keithley microprobe measurement system, current-voltage measurements have been carried out on single composite microfibers after deposition of each layer to optimize the electrical properties of the coated microfibers. The conductivity of the resultant wood microfibers was in the range of 10-2-2 S cm-1 depending on the architecture of the coated layer. Further, the conductivity of the coated wood microfibers increased up to 20 S cm-1 by sandwiching multilayers of conductive co-polymer PEDOT-PSS with CNT-PSS through a polycation (PEI) interlayer. Moreover, paper hand sheets were manufactured from these coated wood microfibers with conductivity ranging from 1 to 20 S cm-1. A paper composite structure consisting of conductive/dielectric/conductive layers that acts as a capacitor has also been fabricated and is reported.

Agarwal, Mangilal; Xing, Qi; Shim, Bong Sup; Kotov, Nicholas; Varahramyan, Kody; Lvov, Yuri

2009-05-01

 
 
 
 
201

Moving beyond mass-based parameters for conductivity analysis of sulfonated polymers  

Energy Technology Data Exchange (ETDEWEB)

Proton conductivity of polymer electrolytes is critical for fuel cells and has therefore been studied in significant detail. The conductivity of sulfonated polymers has been linked to material characteristics in order to elucidate trends. Mass based measurements based on water uptake and ion exchange capacity are two of the most common material characteristics used to make comparisons between polymer electrolytes, but have significant limitations when correlated to proton conductivity. These limitations arise in part because different polymers can have significantly different densities and conduction happens over length scales more appropriately represented by volume measurements rather than mass. Herein, we establish and review volume related parameters that can be used to compare proton conductivity of different polymer electrolytes. Morphological effects on proton conductivity are also considered. Finally, the impact of these phenomena on designing next generation sulfonated polymers for polymer electrolyte membrane fuel cells is discussed.

Kim, Yu Seung [Los Alamos National Laboratory; Pivovar, Bryan [NREL

2009-01-01

202

Fast prototyping of conducting polymer microelectrodes using resistance-controlled high precision drilling  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We present a straightforward method for fast prototyping of microelectrode arrays in the highly conductive polymer poly(3,4-ethylenedioxythiophene) (PEDOT). Microelectrode arrays were produced by electrical resistance-controlled microdrilling through an insulating polymer layer (TOPAS® 5013) coverin...

Kafka, Jan Robert; Geschke, Oliver; Skaarup, Steen; Larsen, Niels Bent

203

PATTERN RECOGNITION STUDIES OF HALOGENATED ORGANIC COMPOUNDS USING CONDUCTING POLYMER SENSOR ARRAYS. (R825323)  

Science.gov (United States)

Direct measurement of volatile and semivolatile halogenated organic compounds of environmental interest was carried out using arrays of conducting polymer sensors. Mathematical expressions of the sensor arrays using microscopic polymer network model is described. A classical, non...

204

Conductive polymer-based microextraction methods: a review.  

UK PubMed Central (United Kingdom)

Conductive polymers (CPs) are classified as materials which exhibit highly reversible redox behavior and the unusual combined properties of metal and plastics. CPs, due to their multifunctionality, ease of synthesis and their stability, have attracted more attentions in different fields of research, including sample preparation. CPs along with several commercial hydrophilic sorbents, are alternative to the commercially available hydrophobic sorbents which despite their high specific surface areas, have poor interactions and retentions in the extraction of polar compounds. This review covers a general overview regarding the recent progress and new applications of CPs toward their synthesis and use in novel extraction and microextraction techniques including solid phase microextraction (SPME), electrochemically controlled solid-phase microextraction (EC-SPME) and other relevant techniques. Furthermore the contribution of nano-structured CPs in these methodologies is also reviewed.

Bagheri H; Ayazi Z; Naderi M

2013-03-01

205

Conductive polymer-based microextraction methods: a review.  

Science.gov (United States)

Conductive polymers (CPs) are classified as materials which exhibit highly reversible redox behavior and the unusual combined properties of metal and plastics. CPs, due to their multifunctionality, ease of synthesis and their stability, have attracted more attentions in different fields of research, including sample preparation. CPs along with several commercial hydrophilic sorbents, are alternative to the commercially available hydrophobic sorbents which despite their high specific surface areas, have poor interactions and retentions in the extraction of polar compounds. This review covers a general overview regarding the recent progress and new applications of CPs toward their synthesis and use in novel extraction and microextraction techniques including solid phase microextraction (SPME), electrochemically controlled solid-phase microextraction (EC-SPME) and other relevant techniques. Furthermore the contribution of nano-structured CPs in these methodologies is also reviewed. PMID:23452781

Bagheri, Habib; Ayazi, Zahra; Naderi, Mehrnoush

2012-12-20

206

Development of bioactive conducting polymers for neural interfaces.  

UK PubMed Central (United Kingdom)

Bioelectrodes for neural recording and neurostimulation are an integral component of a number of neuroprosthetic devices, including the commercially available cochlear implant, and developmental devices, such as the bionic eye and brain-machine interfaces. Current electrode designs limit the application of such devices owing to suboptimal material properties that lead to minimal interaction with the target neural tissue and the formation of fibrotic capsules. In designing an ideal bioelectrode, a number of design criteria must be considered with respect to physical, mechanical, electrical and biological properties. Conducting polymers have the potential to address the synergistic interaction of these properties and show promise as superior coatings for next-generation electrodes in implant devices.

Poole-Warren L; Lovell N; Baek S; Green R

2010-01-01

207

Development of bioactive conducting polymers for neural interfaces.  

Science.gov (United States)

Bioelectrodes for neural recording and neurostimulation are an integral component of a number of neuroprosthetic devices, including the commercially available cochlear implant, and developmental devices, such as the bionic eye and brain-machine interfaces. Current electrode designs limit the application of such devices owing to suboptimal material properties that lead to minimal interaction with the target neural tissue and the formation of fibrotic capsules. In designing an ideal bioelectrode, a number of design criteria must be considered with respect to physical, mechanical, electrical and biological properties. Conducting polymers have the potential to address the synergistic interaction of these properties and show promise as superior coatings for next-generation electrodes in implant devices. PMID:20021239

Poole-Warren, Laura; Lovell, Nigel; Baek, Sungchul; Green, Rylie

2010-01-01

208

PEO-like polymer electrolytes with high room temperature conductivity  

Energy Technology Data Exchange (ETDEWEB)

Polymer electrolytes with room temperature conductivities of >10{sup {minus}4} S/cm were prepared by encapsulating solutions of LiN(SO{sub 2}CF{sub 3}){sub 2} (or LiSO{sub 3}CF{sub 3} or LiPF{sub 6}) in oligomeric poly(ethylene glycol) dimethyl ethers in a poly(vinylidene fluoride)-hexafluoropropene copolymer. The 100 to 200 {micro}m thick membranes prepared have good mechanical strength and are dry with practically no volatility at least up to 70 C. Because of these properties and the structural similarities between poly(ethylene glycol) dimethyl ethers (PEGDME) and polyethylene oxide (PEO) the authors call them PEO-like.

Abraham, K.M.; Jiang, Z. [EIC Labs., Inc., Norwood, MA (United States)

1997-06-01

209

Controlled synthesis of transition metal/conducting polymer nanocomposites  

International Nuclear Information System (INIS)

A novel displacement reaction has been observed to occur between conducting polymers (CP) and metal salts which can be used to fabricate nanostructured CP–metal composites in a one-pot manner. Vanadium pentoxide (V 2O5) nanofiber is used during the synthesis as the reactive seeds to induce the nanofibril CP–metal network formation. The CP–metal nanocomposites exhibit excellent sensory properties for hydrogen peroxide (H2O2) detection, where both high sensitivity and a low detection limit can be obtained. The sensory performance of the CP–metal composite can be further enhanced by a facile microwave treatment. It is believed that the CP–metal nanofibril network can be converted to a carbon–metal network by a microwave-induced carbonization process and result in the sensory enhancement. (paper)

2012-08-24

210

Reversible electrochemical switching of polymer brushes grafted onto conducting polymer films.  

UK PubMed Central (United Kingdom)

We demonstrate the electrochemical switching of conformation of surface-bound polymer brushes, by grafting environmentally sensitive polymer brushes from an electrochemically active conducting polymer (ECP). Using atom transfer radical polymerization (ATRP), we grafted zwitterionic betaine homopolymer and block copolymer brushes of poly(3-(methacryloylamido)propyl)-N,N'-dimethyl(3-sulfopropyl)ammonium hydroxide) (PMPDSAH) and poly(methyl methacrylate)-b-PMPDSAH, from an initiator, surface-coupled to a poly(pyrrole-co-pyrrolyl butyric acid) film. The changes in ionic solution composition in the surface layer, resulting from oxidation and reduction of the ECP, trigger a switch in conformation of the surface-bound polymer brushes, demonstrated here by electrochemical impedance spectroscopy (EIS) and in a change of wettability. The switch is dependent upon temperature in a way that is analogous to the temperature-dependent solubility and aggregation of similar betaine polymers in aqueous solution but has a quite different dependence on salt concentration in solution. The switch is fully reversible and reproducible. We interpret the switching behavior in terms of a transition to a "supercollapsed" state on the surface that is controlled by ions that balance the charge state of the ECP and are adsorbed to the opposite charges of the zwitterionic graft, close to the graft-ECP interface. The behavior is significantly modified by hydrophobic interactions of the block copolymer graft. We speculate that the synergistic combination of properties embodied in these "smart" materials may find applications in electrochemical control of surface wetting and in the interaction with biomolecules and living cells.

Pei Y; Travas-Sejdic J; Williams DE

2012-05-01

211

Electronic transport through Si nanocrystal films: Spin-dependent conductivity studies  

International Nuclear Information System (INIS)

We have investigated paramagnetic defects and their influence on the charge transport in thin films composed of Si nanocrystals (Si-ncs) by means of electrically detected magnetic resonance (EDMR) and conventional electron paramagnetic resonance (EPR). EPR measurements show that the processing applied in the production of films of Si-ncs leads to a considerable generation of Si dangling bonds (Si-dbs). From EDMR spectra, we conclude that the Si-dbs influence the charge transport through Si-ncs networks at room temperature. The low temperature EDMR spectra of P-doped films exhibit, along with Si-dbs resonances, two additional signals: (i) the characteristic hyperfine signature of isolated substitutional P in crystalline Si and (ii) the g=1.998 line, due to exchange-coupled donor electrons. All these resonances give rise to a quenching of the photocurrent through the films, demonstrating that Si-dbs and P-related states are recombination centers of excess charge carriers. The pronounced differences observed between the EDMR and EPR spectra are also discussed.

2007-12-15

212

Effect of ZnCdTe-Alloyed Nanocrystals on Polymer–Fullerene Bulk Heterojunction Solar Cells  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract The photovoltaic properties of solar cell based on the blends of poly[2-methoxy-5-(2-ethylhexoxy-1,4-phenylenevinylene) (MEH-PPV), fullerene (C60), and ZnCdTe-alloyed nanocrystals were investigated. Comparing the spectral response of photocurrent of the MEH-PPV:C60(+ZnCdTe) nanocomposite device with that of the devices based on MEH-PPV:C60and pristine MEH-PPV, one can find that the nanocomposite device exhibits an enhanced photocurrent. In comparing the composite devices with different ZnCdTe:[MEH-PPV + C60] weight ratios of 10 wt% (D1–1), 20 wt% (D1–2), 40 wt% (D1–3), and 70 wt% (D1–4), it was found that the device D1–3exhibits the best performance. The power conversion efficiency (?) is improved doubly compared with that of the MEH-PPV:C60device.

Wang Yan; Hou Yanbing; Tang Aiwei; Feng Zhihui; Feng Bin; Li Yan; Teng Feng

2009-01-01

213

Evolution of conductive network and properties of nanorod/polymer composite under tensile strain.  

UK PubMed Central (United Kingdom)

In this work, the conductive network, probability, and percolation threshold of nanorod/polymer composites under tensile strain are investigated using the molecular dynamics simulation. The internal interactions, including polymer-polymer, polymer-nanorod, and nanorod-nanorod interactions, are taken into account in simulations. In particular, the influence of polymer induced depletion force on the orientation of nanorods is analyzed. Under a constant strain, the conductive stability firstly declines and then rises with the increasing concentration of fillers, and the minimum corresponds to the percolation threshold. As strain increases, the result exhibits a strong anisotropy in the stability of conductive property.

Feng Y; Ning N; Zhang L; Tian M; Zou H; Mi J

2013-07-01

214

Theory of proton conductance of polymer electrolyte membranes  

Energy Technology Data Exchange (ETDEWEB)

A theory is developed for proton conductivity in polymer electrolyte membranes, based on contemporary views on proton transfer in condensed media and on membrane structure. It relates basic proton transfer events in a single pore with the total membrane performance, and thereby connects the structural and kinetic characteristics of the membrane. The theory explains why the activation energy of proton conductivity in a dry membrane is few times higher than in a wet one. The explanation rests on two mechanisms of proton mobility in a water-swollen membrane: the surface mechanism (proton transport in the hydration layer along the pore surface, i.e. between SO{sub 3}-groups via intermediate, hydrated proton states), and the bulk mechanism, which is valid, as we show, already at several atomic distances from the surface. The surface mechanism, in addition to water reorganization energy, has a work-term contribution to activation energy: the price for a proton to leave a SO{sub 3}-group for a free hydrated state. In the bulk, the proton moves between equivalent hydrated states and there are no work terms. We calculated the electrostatic contributions to the work terms and reorganization energy.

Elkerling, M. [Materials Science Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Kornyshev, A.A.; Walbran, S. [Institute for Materials and Processes in Energy Systems III, Research Center Juelich, D-52425 Juelich (Germany); Kuznetsov, A.M. [A.N.Frumkin Institute of Electrochemistry, Russian Academy of Sciences, 117071 Moscow (Russian Federation); Ulstrup, J. [Department of Chemistry, Technical University of Denmark, DK-2800 Lyngby (Denmark)

2001-07-01

215

Soft capacitor fibers using conductive polymers for electronic textiles  

CERN Multimedia

A novel, highly flexible, conductive polymer-based fiber with high electric capacitance is reported. In its crossection the fiber features a periodic sequence of hundreds of conductive and isolating plastic layers positioned around metallic electrodes. The fiber is fabricated using fiber drawing method, where a multi-material macroscopic preform is drawn into a sub-millimeter capacitor fiber in a single fabrication step. Several kilometres of fibers can be obtained from a single preform with fiber diameters ranging between 500um -1000um. A typical measured capacitance of our fibers is 60-100 nF/m and it is independent of the fiber diameter. For comparison, a coaxial cable of the comparable dimensions would have only ~0.06nF/m capacitance. Analysis of the fiber frequency response shows that in its simplest interrogation mode the capacitor fiber has a transverse resistance of 5 kOhm/L, which is inversely proportional to the fiber length L and is independent of the fiber diameter. Softness of the fiber materials...

Gu, Jian Feng; Skorobogatiy, Maksim

2010-01-01

216

Electrochemical determination of mesoscopic phenomena, defect states in CdSe nanocrystals and charge carrier manipulability  

International Nuclear Information System (INIS)

[en] The review gives an overview of cyclic voltametry measurements performed on CdSe nanocrystals (so called quantum dots). Data of relevant publications is gathered and newly interpreted to give complete insights in charge transfer processes at QD surfaces. In specific, it is focused on the size-dependent electronic properties (quantum-size-effect), the characterization of surface defects, and the characterization of hybrid nanocrystal/conducting polymer composites. (author)

2008-01-01

217

Mixed ionic and electronic conductivity in polymers. Progress report, January 1, 1989--December 31, 1989  

Energy Technology Data Exchange (ETDEWEB)

The conductivity of iodine-containing polymers was investigated and conductivity along polyiodide chains is implicated by the concentration dependence of the conductivity data and spectroscopic measurements. On the theoretical side, entropy based models were developed to describe ion motion in polymers.

Shriver, D.F.

1990-06-01

218

Lithium ion conductivity of blend polymer electrolytes based on borate polymers containing fluoroalkane dicarboxylate and poly(ethylene oxide)  

International Nuclear Information System (INIS)

Single ion conducting blend polymer electrolytes were prepared from borate complex polymers containing fluoroalkane dicarboxylate and two methoxy [oligo(ethylene oxide)] side chains and poly(ethylene oxide) (PEO). Mechanical properties were greatly improved by blending with PEO. Ionic conductivity was dependent on the chain length of oligoether groups, and decreased with increasing PEO content. The optimized blend polymer B (n 7.2)-PEO (80:20 wt.%) exhibited ionic conductivity of 2 x 10-6 S cm-1 at 30 deg. C.

2004-11-30

219

Conductive polymers derived from iron, ruthenium, and osmium metalloporphyrins: The shish-kebab approach  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The synthesis and characterization of pyrazine-bridged polymers of iron(II/III), ruthenium(II/III), and osmium(II/III) octaethylporphyrin (dubbed “shish-kebab” polymers) are presented. Optical and dc conductivity measurements reveal that the ruthenium and osmium polymers, when partially oxidized, ar...

Collman, James P.; McDevitt, John T.; Yee, Gordon T.; Leidner, Charles R.; McCullough, Laughlin G.; Little, William A.

220

Using artificial intelligence methods to design new conducting polymers  

Directory of Open Access Journals (Sweden)

Full Text Available In the last years the possibility of creating new conducting polymers exploring the concept of copolymerization (different structural monomeric units) has attracted much attention from experimental and theoretical points of view. Due to the rich carbon reactivity an almost infinite number of new structures is possible and the procedure of trial and error has been the rule. In this work we have used a methodology able of generating new structures with pre-specified properties. It combines the use of negative factor counting (NFC) technique with artificial intelligence methods (genetic algorithms - GAs). We present the results for a case study for poly(phenylenesulfide phenyleneamine) (PPSA), a copolymer formed by combination of homopolymers: polyaniline (PANI) and polyphenylenesulfide (PPS). The methodology was successfully applied to the problem of obtaining binary up to quinternary disordered polymeric alloys with a pre-specific gap value or exhibiting metallic properties. It is completely general and can be in principle adapted to the design of new classes of materials with pre-specified properties.

Ronaldo Giro; Márcio Cyrillo; Douglas Soares Galvão

2003-01-01

 
 
 
 
221

Using artificial intelligence methods to design new conducting polymers  

Scientific Electronic Library Online (English)

Full Text Available Abstract in english In the last years the possibility of creating new conducting polymers exploring the concept of copolymerization (different structural monomeric units) has attracted much attention from experimental and theoretical points of view. Due to the rich carbon reactivity an almost infinite number of new structures is possible and the procedure of trial and error has been the rule. In this work we have used a methodology able of generating new structures with pre-specified propert (more) ies. It combines the use of negative factor counting (NFC) technique with artificial intelligence methods (genetic algorithms - GAs). We present the results for a case study for poly(phenylenesulfide phenyleneamine) (PPSA), a copolymer formed by combination of homopolymers: polyaniline (PANI) and polyphenylenesulfide (PPS). The methodology was successfully applied to the problem of obtaining binary up to quinternary disordered polymeric alloys with a pre-specific gap value or exhibiting metallic properties. It is completely general and can be in principle adapted to the design of new classes of materials with pre-specified properties.

Giro, Ronaldo; Cyrillo, Márcio; Galvão, Douglas Soares

2003-12-01

222

Correlaction Effects on the Band Gap of Conducting Polymers  

CERN Multimedia

By applying the projection technique to the computation of excitation energies, we study the correlation effects on the band gap of conducting polymers. In the presence of an additional electron or hole, the correlation induces a polarization cloud around the addi- tional particle, which forms a polaron. For the excitation energy of a polaron,there is a competition between a {\\it loss} of the correla- tion energy in the ground state and a {\\it gain} of polarization energy. For the Hubbard interaction, the {\\it loss} of correlation energy is dominant and correlations increase the band gap.However,for long-range interactions, the {\\it gain} of polarization energy is dominant and correlations decrease the band gap. Screening the long- range interaction suppresses the {\\it gain}of the polarization energy so that correlations again increase the band gap.A small dimerization is always favorable to the correlation effects. For {\\it trans}-poly- acetylene, we obtain the on-site repulsion $U=4.4$eV and the nearest- ne...

Wu Chang Qin

1992-01-01

223

Substrate dependent stability of conducting polymer coatings on medical electrodes.  

UK PubMed Central (United Kingdom)

Conducting polymer (CP) coatings on medical electrodes have the potential to provide superior performance when compared to conventional metallic electrodes, but their stability is strongly dependant on the substrate properties. The aim of this study was to examine the effect of laser roughening of underlying platinum (Pt) electrode surfaces on the mechanical, electrical and biological performance of CP coatings. In addition, the impact of dopant type on electrical performance and stability was assessed. The CP poly(ethylene dioxythiophene) (PEDOT) was coated on Pt microelectrode arrays, with three conventional dopant ions. The in vitro electrical characteristics were assessed by cyclic voltammetry and biphasic stimulation. Results showed that laser roughening of the underlying substrate did not affect the charge injection limit of the coated material, but significantly improved the passive stability and chronic stimulation lifetime without failure of the coating. Accelerated material ageing and long-term biphasic stimulus studies determined that some PEDOT variants experienced delamination within as little as 10 days when the underlying Pt was smooth, but laser roughening to produce a surface index of 2.5 improved stability, such that more than 1.3 billion stimulation cycles could be applied without evidence of failure. PEDOT doped with paratoluene sulfonate (PEDOT/pTS) was found to be the most stable CP on roughened Pt, and presented a surface topography which encouraged neural cell attachment.

Green RA; Hassarati RT; Bouchinet L; Lee CS; Cheong GL; Yu JF; Dodds CW; Suaning GJ; Poole-Warren LA; Lovell NH

2012-09-01

224

Molecular motion in polymer electrolytes. An investigation of methods for improving the conductivity of solid polymer electrolytes  

International Nuclear Information System (INIS)

Three methods were explored with a view to enhancing the ionic conductivity of polymer electrolytes; namely the addition of an inert, inorganic filler, the addition of a plasticizer and the incorporation of the electrolyte in the pores of silica matrices. There have been a number of reports, which suggest the addition of nanocrystalline oxides to polymer electrolytes increases the ionic conductivities by about a factor of two. In this thesis studies of the polymer electrolyte NaSCN.P(EO)8 with added nanocrystalline alumina powder are reported which show no evidence of enhanced conductivity. The addition of a plasticizer to polymer electrolytes will increase the ionic conductivity. A detailed study was made of the polymer electrolytes LiT.P(EO)10 and LiClO4.P(EO)10 with added ethylene carbonate plasticizer. The conductivities showed an enhancement, however this disappeared on heating under vacuum. The present work suggests that the plasticised system is not thermodynamically stable and will limit the applications of the material. A series of samples were prepared from the polymer electrolyte LiT.P(EO)8 and a range of porous silicas. The silicas were selected to give a wide range of pore size and included Zeolite Y, ZSM5, mesoporous silica and a range of porous glasses. This gave pore sizes from less than one nm to 50 nm. A variety of experiments, including X-ray diffraction, DSC and NMR, showed that the polymer electrolyte entered to pores of the silica. As a result the polymer was amorphous and the room temperature conductivity was enhanced. The high temperature conductivity was not increased above that for the pure electrolyte. The results suggest that this could be employed in applications, however would require higher conducting electrolytes to be of practical benefit. (author)

2002-01-01

225

Molecular motion in polymer electrolytes. An investigation of methods for improving the conductivity of solid polymer electrolytes  

Energy Technology Data Exchange (ETDEWEB)

Three methods were explored with a view to enhancing the ionic conductivity of polymer electrolytes; namely the addition of an inert, inorganic filler, the addition of a plasticizer and the incorporation of the electrolyte in the pores of silica matrices. There have been a number of reports, which suggest the addition of nanocrystalline oxides to polymer electrolytes increases the ionic conductivities by about a factor of two. In this thesis studies of the polymer electrolyte NaSCN.P(EO){sub 8} with added nanocrystalline alumina powder are reported which show no evidence of enhanced conductivity. The addition of a plasticizer to polymer electrolytes will increase the ionic conductivity. A detailed study was made of the polymer electrolytes LiT.P(EO){sub 10} and LiClO{sub 4}.P(EO){sub 10} with added ethylene carbonate plasticizer. The conductivities showed an enhancement, however this disappeared on heating under vacuum. The present work suggests that the plasticised system is not thermodynamically stable and will limit the applications of the material. A series of samples were prepared from the polymer electrolyte LiT.P(EO){sub 8} and a range of porous silicas. The silicas were selected to give a wide range of pore size and included Zeolite Y, ZSM5, mesoporous silica and a range of porous glasses. This gave pore sizes from less than one nm to 50 nm. A variety of experiments, including X-ray diffraction, DSC and NMR, showed that the polymer electrolyte entered to pores of the silica. As a result the polymer was amorphous and the room temperature conductivity was enhanced. The high temperature conductivity was not increased above that for the pure electrolyte. The results suggest that this could be employed in applications, however would require higher conducting electrolytes to be of practical benefit. (author)

Webster, Mark Ian

2002-07-01

226

Pattern-definable and low cost fabrication of nanopatterned conducting polymer film on flexible substrates.  

UK PubMed Central (United Kingdom)

This study reports the pattern definable and low cost fabrication of nanopatterned conducting polymer film on flexible substrates. Noble nanopatterned polymer hard template was fabricated by using nanoimprint lithography (NIL) and used for electropolymerization of conducting polymer. Conducting polymer was electrochemically deposited on the template and transferred over to flexible substrates. Eventually conducting polymer films with various nanopatterns were fabricated on flexible substrates. High pattern definability was achieved by nanoimprinted polymer template, which was molded from lithographically fabricated stamp. Low cost fabrication was accomplished due to low cost NIL, reusable polymer templates, and low material consumption of electrodeposition. The electrodeposited films were transferred using double sided tape. Because the templates are made of flexible polymer, the transfer bonding method applied in this study is adaptable to both wafers and flexible polymer substrates. The fabricated nanopatterned conducting polymer film can be applied to gas sensors, super capacitors, super wetting films, and neuron interfaces due to its characteristic of high surface to volume. For an illustrative application, the gas sensing properties of films were tested. The result showed enhanced sensing characteristic with nanopatterned film, which are attributed to the high surface to volume ratio of nanopatterned films.

Lee J; Choi DG; Altun AO; Kim KD; Choi JH; Lee ES; Jeong JH

2010-09-01

227

Redox-active charge carriers of conducting polymers as a tuner of conductivity and its potential window.  

Science.gov (United States)

Electric conductivity of conducting polymers has been steadily enhanced towards a level worthy of being called its alias, "synthetic metal". PEDOT:PSS (poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulfonate)), as a representative conducting polymer, recently reached around 3,000?S cm(-1), the value to open the possibility to replace transparent conductive oxides. The leading strategy to drive the conductivity increase is solvent annealing in which aqueous solution of PEDOT:PSS is treated with an assistant solvent such as DMSO (dimethyl sulfoxide). In addition to the conductivity enhancement, we found that the potential range in which PEDOT:PSS is conductive is tuned wider into a negative potential direction by the DMSO-annealing. Also, the increase in a redox-active fraction of charge carriers is proposed to be responsible for the enhancement of conductivity in the solvent annealing process. PMID:23949091

Park, Han-Saem; Ko, Seo-Jin; Park, Jeong-Seok; Kim, Jin Young; Song, Hyun-Kon

2013-08-16

228

Performance of conducting polymer electrodes for stimulating neuroprosthetics.  

UK PubMed Central (United Kingdom)

OBJECTIVE: Recent interest in the use of conducting polymers (CPs) for neural stimulation electrodes has been growing; however, concerns remain regarding the stability of coatings under stimulation conditions. These studies examine the factors of the CP and implant environment that affect coating stability. The CP poly(ethylene dioxythiophene) (PEDOT) is examined in comparison to platinum (Pt), to demonstrate the potential performance of these coatings in neuroprosthetic applications. APPROACH: PEDOT is coated on Pt microelectrode arrays and assessed in vitro for charge injection limit and long-term stability under stimulation in biologically relevant electrolytes. Physical and electrical stability of coatings following ethylene oxide (ETO) sterilization is established and efficacy of PEDOT as a visual prosthesis bioelectrode is assessed in the feline model. MAIN RESULTS: It was demonstrated that PEDOT reduced the potential excursion at a Pt electrode interface by 72% in biologically relevant solutions. The charge injection limit of PEDOT for material stability was found to be on average 30× larger than Pt when tested in physiological saline and 20× larger than Pt when tested in protein supplemented media. Additionally stability of the coating was confirmed electrically and morphologically following ETO processing. It was demonstrated that PEDOT-coated electrodes had lower potential excursions in vivo and electrically evoked potentials (EEPs) could be detected within the visual cortex. SIGNIFICANCE: These studies demonstrate that PEDOT can be produced as a stable electrode coating which can be sterilized and perform effectively and safely in neuroprosthetic applications. Furthermore these findings address the necessity for characterizing in vitro properties of electrodes in biologically relevant milieu which mimic the in vivo environment more closely.

Green RA; Matteucci PB; Hassarati RT; Giraud B; Dodds CW; Chen S; Byrnes-Preston PJ; Suaning GJ; Poole-Warren LA; Lovell NH

2013-02-01

229

Towards P-Type Conductivity in SnO2 Nanocrystals through Li Doping  

Energy Technology Data Exchange (ETDEWEB)

This paper examines electrical transport properties and Li doping in SnO2 synthesized by the sol–gel method. Solid-state 7Li-NMR lineshapes reveal that Li ions occupy two distinct sites with differing dynamic mobilities. The chemical exchange rate between the two sites is, however, too slow for detection on the NMR timescale. Compressed nanoparticulate films of this doped semiconductor exhibit a positive Seebeck coefficient implying a p-type conductivity. A variable-temperature direct current conductivity, over a 25–350 ?C temperature range, follows an Efros–Shklovskii variable range hopping (ES-VRH) conduction mechanism (ln(?) versus T ?1/2) at temperatures below 100 ?C with a crossover to 2D Mott variable range hopping (M-VRH) (ln(?) versus T ?1/3) conduction at temperatures above 250 ?C. In a transition region between these two limiting behaviors, the dc resistivity exhibits an anomalous temperature-independent plateau. We suggest that its origin may lie in a carrier inversion phenomenon wherein the majority carriers switch from holes to electrons due to Li ion expulsion from the crystalline core and creation of oxygen vacancies generated by loss of oxygen at elevated temperatures.

Chaparadza, Allen; Rananavare, Shankar B.

2010-01-22

230

Property of individual conducting-polymer nanowires: conductance and FET devices  

Science.gov (United States)

Electronic devices using organic molecules and nanowires have been intensively studied in dream of a smart life utilizing charming functions of organic materials, that are thin, light, flexible and yet inexpensive and safe for environment. A key step for measuring the property of organic nanowires and evaluating the performance of the nanowire devices is how to access them by appropriate nanoscopic methods. Scanning probe microscopy (SPM) based nanofabrication (SP nanofabrication) has been used to fabricate two- or four-probe fine electrodes and several kinds of nanowires made of conducting polymers have been evaluated by SPM and the fine electrodes made with Pt thin film fabricated on SiO2/doped Si or sapphire substrates [1,2]. We have tested conductivity of single poly (3,4-ethylenedioxythiophene) / poly (styrenesulfonate) (PEDOT/PSS) nanowires. After cutting each nanowires placed on the fine electrodes, the current was checked and we were able to confirm that the conductivity was derived from the PEDOT nanowires themselves. The temperature dependence of the conductivity was explained by the quasi one-dimensional variable range hopping (VRH) model. We also will discuss on the field-effect-transistor (FET) made of a single nanowire. In collaboration with: S. Heike, M. Fujimori, Y. Suwa (ARL), H. Ichihara, S. Samitsu, A. Inomata, T. Shimomura, K. Ito (Univ. Tokyo), K. Miki, T. Ohno (NIMS), H. Mizuseki (IMR), Y. Terada, H. Shigekawa (Univ. Tsukuba). [1] J. P. Hill, W. Jin, A. Kosaka, T. Fukushima, H. Ichihara, T. Shimomura, K. Ito, T. Hashizume, N. Ishii, and T. Aida, Science 304, 1481 (2004). [2] S. Samitsu, T. Shimomura, K. Ito, S. Heike, M. Fujimori, S. Heike, and T. Hashizume, Appl. Phys. Lett., 86, 233103 (2005).

Hashizume, Tomihiro

2006-03-01

231

Stabilization of Conducting Polymers with CMC: Rheological Approach  

Science.gov (United States)

Polyaniline (PAn) and Polypyrrole (PPy) were stabilized in aqueous medium using carboxy methyl cellulose (CMC) as an efficient steric stabilizer. Both these dispersions were stable for few days and have shown different rheological responses. PAn-CMC resembles to a semidilute polymer solution while PPy-CMC resembles to a reversible polymer network. After few days PPy-CMC formed a soft gel that hardened gradually in course of time.

Gangopadhyay, Rupali

2011-07-01

232

Conductive polymers derived from iron, ruthenium, and osmium metalloporphyrins: The shish-kebab approach.  

UK PubMed Central (United Kingdom)

The synthesis and characterization of pyrazine-bridged polymers of iron(II/III), ruthenium(II/III), and osmium(II/III) octaethylporphyrin (dubbed "shish-kebab" polymers) are presented. Optical and dc conductivity measurements reveal that the ruthenium and osmium polymers, when partially oxidized, are highly conductive. Electrochemical and ESR results are presented that indicate the existence of an interesting metal-centered conduction pathway. Unlike most of the previously reported porphyrinic molecular metals in which the conduction electrons are macrocyclic-based, electron transport in these materials proceeds exclusively along the metal-pyrazine backbone.

Collman JP; McDevitt JT; Yee GT; Leidner CR; McCullough LG; Little WA; Torrance JB

1986-07-01

233

High Seebeck effects from conducting polymer: Poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) based thin-film device with hybrid metal/polymer/metal architecture  

Energy Technology Data Exchange (ETDEWEB)

Conductive polymers are of particular interest for thermoelectric applications due to their low thermal conductivity and relatively high electrical conductivity. In this study, commercially available conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) was used in a hybrid metal/polymer/metal thin film design in order to achieve a high Seebeck coefficient with the value of 252lV/k on a relatively low temperature scale. Polymer film thickness was varied in order to investigate its influence on the Seebeck effect. The high Seebeck coefficient indicates that the metal/polymer/metal design can develop a large entropy difference in internal energy of charge carriers between high and low-temperature metal electrodes to develop electrical potential due to charge transport in conducting polymer film through metal/polymer interface. Therefore, the metal/polymer/metal structure presents a new design to combine inorganic metals and organic polymers in thin-film form to develop Seebeck devices

Stanford, Michael G [ORNL; Wang, Hsin [ORNL; Ivanov, Ilia N [ORNL; Hu, Bin [University of Tennessee, Knoxville (UTK)

2012-01-01

234

A conducting polymer artificial muscle with 12% linear strain  

DEFF Research Database (Denmark)

The efforts given to optimize the linear strain response of polypyrrole (PPy) doped with alkyl benzene sulfonate (ABS) as these systems show particularly good chemical stability in aqueous systems and little toxicity are presented. The aims of the optimization is to obtain maximum length changes in a freely suspended polymer foil in response to a potential change and it includes attention to the composition of the polymer, to the synthesis conditions, and involves microstructuring of the polymer. As such, an analysis of the influence of the alkyl chain length on the properties of PPy doped with ABSs has shown that the obtainable strain decreases with increasing chain length for alkyl chains longer than C$-8$/.

Bay, Lasse; West, Keld

2003-01-01

235

Electrochemical Switching of Conductance with Diarylethene-Based Redox-Active Polymers  

DEFF Research Database (Denmark)

Reversible switching of conductance using redox triggered switching of a polymer-modified electrode is demonstrated. A bifunctional monomer comprising a central electroswitchable core and two bithiophene units enables formation of a film through anodic electropolymerization. The conductivity of the polymer can be switched electrochemically in a reversible manner by redox triggered opening and closing of the diarylethene unit. In the closed state, the conductivity of the modified electrode is higher than in the open state.

Logtenberg, Hella; van der Velde, Jasper H. M.

2012-01-01

236

Hybrid solar cells of conjugated polymers metal-oxide nanocrystals blends; state of the art and future research challenges in Indonesia  

Science.gov (United States)

Ever-increasing world energy demand, depleting non-renewable energy resources and disruptive climate change due to greenhouse gases has aroused much interest in alternative renewable energy sources. Solar energy is one of the best available alternatives, for it is both abundant and clean. Solar cell is an effective device for converting solar energy into electricity. Indonesia is located on the equator where the sunlight is always available in abundance throughout the year; therefore solar cell would become the main source of electrical energy in Indonesia. However, the high cost of inorganic solar cells in spite of their high power conversion efficiency (PCE) has been a major constrain for their mass utilization in Indonesia. The only way to reduce the cost of production and installation is to find other materials which offer low-cost and easy processing into solar cells. Polymer solar cells have been intensively investigated for high performance and low-cost solar cells. Today, 9-11% power conversion efficiency (PCE) of small area polymer solar cells and 2-4% PCE of large area or module solar cells are already achieved. However, for practical application and mass production, 10% or higher PCE of module solar cells is highly required. The main strategic issue for improving the PCE is to use blend of conjugated polymer-metal oxide nanocrystals as active materials for hybrid solar cells, due to the good combination of the versatile solution processability of conjugated polymers and high charge carrier mobility of metal-oxide nanocrystals. In this paper, current development of hybrid solar cells worldwide and future research challenges in Indonesia will be discussed.

Bahtiar, Ayi

2013-09-01

237

Molecular motion in polymer electrolytes. An investigation of methods for improving the conductivity of solid polymer electrolytes  

CERN Multimedia

Three methods were explored with a view to enhancing the ionic conductivity of polymer electrolytes; namely the addition of an inert, inorganic filler, the addition of a plasticizer and the incorporation of the electrolyte in the pores of silica matrices. There have been a number of reports, which suggest the addition of nanocrystalline oxides to polymer electrolytes increases the ionic conductivities by about a factor of two. In this thesis studies of the polymer electrolyte NaSCN.P(EO) sub 8 with added nanocrystalline alumina powder are reported which show no evidence of enhanced conductivity. The addition of a plasticizer to polymer electrolytes will increase the ionic conductivity. A detailed study was made of the polymer electrolytes LiT.P(EO) sub 1 sub 0 and LiClO sub 4.P(EO) sub 1 sub 0 with added ethylene carbonate plasticizer. The conductivities showed an enhancement, however this disappeared on heating under vacuum. The present work suggests that the plasticised system is not thermodynamically stabl...

Webster, M I

2002-01-01

238

Polarons and radiation-induced conductivity of polymers  

International Nuclear Information System (INIS)

A physical model of charge transport and localization in a polymer is formulated: localization is realized in bulk traps -dense blocks (crystallites and amorphous clusters); the transport is determined by permeability of potential barriers in loose interblock layers. Mathematical model of localization and transport is added by the continuity equations for bipolarons with the characteristic of them processes of production, drift and recombination.

1992-01-01

239

Tunable positive temperature coefficient of resistivity in an electrically conducting polymer/graphene composite  

Science.gov (United States)

The graphene nanosheet (GNS)/ultrahigh molecular weight polyethylene composite with a two-dimensional conductive network of GNSs exhibits an increasing positive temperature coefficient (PTC) of resistivity while thermally treated at a certain temperature. This anomalous phenomenon is originated from the reduced viscosity of polymer matrix, crystallization induced local flow and weak interactions among the overlapping joints of GNSs, which allow GNSs to migrate to the polymer matrix, thus weakening the conductive paths and increasing the PTC intensity. A facile approach is accordingly developed to prepare a conductive polymer composite with a tunable PTC intensity.

Pang, Huan; Zhang, Yi-Chuan; Chen, Tao; Zeng, Bao-Qing; Li, Zhong-Ming

2010-06-01

240

Reversible post-breakdown conduction in aluminum oxide-polymer capacitors  

Science.gov (United States)

Aluminum/Al2O3/polymer/metal capacitors submitted to a low-power constant current stress undergo dielectric breakdown. The post-breakdown conduction is metastable, and over time the capacitors recover their original insulating properties. The decay of the conduction with time follows a power law (1/t)?. The magnitude of the exponent ? can be raised by application of an electric field and lowered to practically zero by optical excitation of the polyspirofluorene polymer. The metastable conduction is attributed to formation of metastable pairs of oppositely charged defects across the oxide-polymer interface, and the self-healing is related to resistive switching.

Chen, Qian; Gomes, Henrique L.; Rocha, Paulo R. F.; de Leeuw, Dago M.; Meskers, Stefan C. J.

2013-04-01

 
 
 
 
241

Tunable Optical Stop Band Utilizing Thermochromism of Synthetic Opal Infiltrated with Conducting Polymer  

Science.gov (United States)

Conducting polymers can be infiltrated into a nanoscale interconnected regular array of voids in synthetic opal in the liquid state upon heating. Optical properties such as transmission and reflection spectra of the synthetic opal infiltrated with conducting polymer poly(3-alkylthiophene) have been found to change drastically with temperature. The control of the stop band by utilizing the change of the refractive index associated with the thermochromism of synthetic opal infiltrated with conducting polymer is proposed as an example of a tunable photonic crystal.

Satoh, Shigenori; Kajii, Hirotake; Kawagishi, Yoshiaki; Fujii, Akihiko; Ozaki, Masanori; Yoshino, Katsumi

1999-12-01

242

Melt processed electrically conductive binary and ternary immiscible polymer/polyaniline blends  

Energy Technology Data Exchange (ETDEWEB)

In the present study, conductive binary and ternary blends of PANI with thermoplastic polymers were prepared by melt processing. The binary blends' investigation focused on the morphology and on the resulting electrical conductivity. Generally, the level of interaction between the doped PANI and the matrix polymer determines the blend morphology, and thus, its electrical conductivity. The morphology of a conductive network is described by a primary structure of small dispersed polyaniline particles, interconnected by secondary short range fine fibrillar structure. In blends containing a semicrystalline matrix the doped PANI network locates within the amorphous regions, leading to a reduction of the percolation concentration. The ternary blends' investigation focused on a system containing two co-continuous immiscible thermoplastic polymers and PANI. The PANI is preferably located in one of the matrix polymers. This concentration effects enables high electrical conductivities at low PANI contents.

Zilberman, M.; Siegmann, A.; Narkis, M.

1998-07-01

243

Electrically conducting polymers from phenylacetylene substituted Schiff`s base momomers  

Energy Technology Data Exchange (ETDEWEB)

Electrically conducting polymers have been synthesized from novel mono- or difunctional phenylacetylene-substituted Schiff`s base monomers. These monomers melt to a viscous liquid state, and on continued heating above about 300 C, thermally polymerize to form an electrically insulating thermoset polymers. On further postcure heat treatment, the polymers become electroconductive showing a bulk conductivity of approximately 10{sup -2}S/cm. Because the monomers remain in a liquid stage for 1-2h, depending on the cure conditions, moldings, castings, and pre-pregs can be fabricated using conventional processing techniques. In addition, since reactive dopants are not used, the resulting polymers and conductivity are stable in ambient as well as more aggressive environments, allowing them to function at 300 C and above. The monomers are well characterized, but the structure of the cured and postcured polymers are not yet well defined because of their high stability and intractability in the cured state. (orig.)

Kim, I. [Dept. of Chemical Engineering, Univ. of Ulsan (Korea, Republic of); Lee, D.J. [R and D Center, Kumho and Co., Kwangju (Korea, Republic of)

1995-03-01

244

A General Formula for Ion Concentration-Dependent Electrical Conductivities in Polymer Electrolytes  

Directory of Open Access Journals (Sweden)

Full Text Available Problem statement: The aim of this study is to develop a model for describing the effect of ion concentration on the electrical conductivity of polymer electrolytes by considering two mechanisms simultaneously: Enhancements of ion concentration and amorphous phase. Approach: The problems based on new observations in polymer electrolyte when ion concentration in the polymer electrolytes was increased, both the fraction of amorphous phase and the charge carriers increase simultaneously. The model was based on the assumption when ions were inserted into the polymer host, there was an optimum distance between ions at which the ions move easily throughout the polymer. The average distance between ions in the polymer depends on the ion concentration. And we also considered the effect of ion concentration on the amorphous phase in the polymer. Results: We inspected the validity of the model by comparing the model predictions with various experimental data. The new analytical expressions for the electrical conductivity dependent of ion concentration was developed by considering two mechanisms simultaneously in polymer electrolytes, i.e., enhancement of the carries concentration and amorphous phase fraction. Interestingly, most of fitting parameters were not arbitrarily selected, but were derived from the appropriate experimental data. Conclusion: The model can be used to explain the conductivity behavior of other polymer electrolyte systems by selecting appropriately less number of parameters. This model result is fully supported by available experimental data.

Mahardika P. Aji; Masturi Last Name; Satria Bijaksana; Khairurrijal Last Name; Mikrajuddin Abdullah

2012-01-01

245

Understanding the Role of Different Conductive Polymers in Improving the Nanostructured Sulfur Cathode Performance.  

UK PubMed Central (United Kingdom)

Lithium sulfur batteries have brought significant advancement to the current state-of-art battery technologies because of their high theoretical specific energy, but their wide-scale implementation has been impeded by a series of challenges, especially the dissolution of intermediate polysulfides species into the electrolyte. Conductive polymers in combination with nanostructured sulfur have attracted great interest as promising matrices for the confinement of lithium polysulfides. However, the roles of different conductive polymers on the electrochemical performances of sulfur electrode remain elusive and poorly understood due to the vastly different structural configurations of conductive polymer-sulfur composites employed in previous studies. In this work, we systematically investigate the influence of different conductive polymers on sulfur cathode based on conductive polymer-coated hollow sulfur nanospheres with high uniformity. Three of the most well-known conductive polymers, polyaniline (PANI), polypyrrole (PPY), and poly(3,4-ethylenedioxythiophene) (PEDOT) were coated, respectively, onto monodisperse hollow sulfur nanopsheres through a facile, versatile, and scalable polymerization process. The sulfur cathodes made from these well-defined sulfur nanoparticles act as ideal platforms to study and compare how coating thickness, chemical bonding as well as the conductivity of the polymers affected the sulfur cathode performances from both experimental observations and theoretical simulations. We found that the capability of these three polymers in improving long-term cycling stability and high-rate performance of sulfur cathode decreased in the order of PEDOT > PPY > PANI. High specific capacities and excellent cycle life were demonstrated for sulfur cathodes made from these conductive polymer-coated hollow sulfur nanospheres.

Li W; Zhang Q; Zheng G; Seh ZW; Yao H; Cui Y

2013-10-01

246

Regiochemistry of Poly(3-Hexylthiophene): Synthesis and Investigation of a Conducting Polymer  

Science.gov (United States)

A series of experiments for undergraduate laboratory courses (e.g., organic, polymer, inorganic) have been developed. These experiments focus on understanding the regiochemistry of the conducting polymer poly(3-hexylthiophene) (P3HT). The substitution patterns in P3HTs control their conformational features, which, in turn, dictates the [pi]…

Pappenfus, Ted M.; Hermanson, David L.; Kohl, Stuart G.; Melby, Jacob H.; Thoma, Laura M.; Carpenter, Nancy E.; Filho, Demetrio A. da Silva; Bredas, Jean-Luc

2010-01-01

247

A versatile chemical tool for the preparation of conductive graphene-based polymer nanocomposites.  

UK PubMed Central (United Kingdom)

A general route for the functionalization of graphene and graphene derivatives with a low molecular weight polymer by thiol-radical reactions is reported. Polymer-modified graphene is employed as a filler for high density polyethylene to generate materials with good electrical conductivity.

Castelaín M; Martínez G; Ellis G; Salavagione HJ

2013-08-01

248

Li ion conducting gel polymer electrolytes based on Poly(vinyl acetate)  

Science.gov (United States)

A novel gel polymer electrolyte based on poly(vinyl acetate) and poly(vinylidene fluoride) with different plasticizers was prepared and studied by X-ray diffraction and Ac impedance methods. The blend polymer electrolyte containing propylene carbonate (PC) exhibits the highest conductivity 0.922 × 10-2 Scm-1 at room temperature and the results were discussed.

Rajendran, S.; Mathew, Chithra M.; Marimuthu, T.; Kesavan, K.

2013-06-01

249

A versatile chemical tool for the preparation of conductive graphene-based polymer nanocomposites.  

UK PubMed Central (United Kingdom)

A general route for the functionalization of graphene and graphene derivatives with a low molecular weight polymer by thiol-radical reactions is reported. Polymer-modified graphene is employed as a filler for high density polyethylene to generate materials with good electrical conductivity.

Castelaín M; Martínez G; Ellis G; Salavagione HJ

2013-09-01

250

Electrical Conductivity Studies on Individual Conjugated Polymer Nanowires: Two-Probe and Four-Probe Results  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Two- and four-probe electrical measurements on individual conjugated polymer nanowires with different diameters ranging from 20 to 190 nm have been performed to study their conductivity and nanocontact resistance. The two-probe results reveal that all the measured polymer nanowires with different di...

Long, YunZe; Duvail, JeanLuc; Li, MengMeng; Gu, Changzhi; Liu, Zongwen; Ringer, Simon P

251

Conductivity studies of a chitosan-based polymer electrolyte  

Energy Technology Data Exchange (ETDEWEB)

Ionic conductivity for the chitosan-NH{sub 4}CF{sub 3}SO{sub 3} system was conducted over a wide range of frequency and at temperatures between 298 and 313 K. Dielectric data were analyzed using complex permittivity {epsilon} {sup *} and complex electrical modulus M {sup *} for the sample with the highest ionic conductivity at various temperatures. The temperature-dependent conductivity data obeys Arrhenius relationship. Jonschers universal power law was used to analyze AC conductivity of the sample. Hopping frequency was determined and activation energy of hopping is almost equal to the activation energy of conduction. The AC conductivity master curve was obtained for the highest conducting sample when scaled vertically by {sigma} {sub DC} and horizontally by {omega} {sub P}.

Khiar, A.S.A. [Physics Department, University of Malaya, 50603 Kuala Lumpur (Malaysia); Puteh, R. [Physics Department, University of Malaya, 50603 Kuala Lumpur (Malaysia); Arof, A.K. [Physics Department, University of Malaya, 50603 Kuala Lumpur (Malaysia)]. E-mail: akarof@um.edu.my

2006-03-01

252

Influence of hyperbranched polymer structure on ionic conductivity in composite polymer electrolytes of PEO/hyperbranched polymer/BaTiO{sub 3}/Li salt system  

Energy Technology Data Exchange (ETDEWEB)

The influence of the hyperbranched polymer (HBP) structure such as molecular weights, molecular weight distribution, chain-end, ethylene oxide (EO) chain lengths on the ionic conductivity of the composite polymer electrolytes composed of poly(ethylene oxide) (PEO), BaTiO{sub 3} as a ceramic filler, LiN(CF{sub 3}SO{sub 2}){sub 2} as a lithium salt, and HBP as a plasticizer were investigated. The difference in the molecular weights of the HBP did not affect significantly the ionic conductivity. However, molecular weight distribution of the HBP might affect the ionic conductivity of the composite polymer electrolyte, which decreased with broadening of the molecular weight distribution. Further branching at the chain-end structure in the HBP led to a decrease in the ionic conductivity. The HBP with a longer EO chain length was effective to an enhancement of the ionic conductivity. (author)

Itoh, Takahito; Horii, Seiji; Uno, Takahiro; Kubo, Masataka [Mie University (Japan). Faculty of Engineering; Yamamoto, Osamu [Genesis Research Institute, Nagoya (Japan)

2004-11-30

253

Influence of hyperbranched polymer structure on ionic conductivity in composite polymer electrolytes of PEO/hyperbranched polymer/BaTiO3/Li salt system  

International Nuclear Information System (INIS)

The influence of the hyperbranched polymer (HBP) structure such as molecular weights, molecular weight distribution, chain-end, ethylene oxide (EO) chain lengths on the ionic conductivity of the composite polymer electrolytes composed of poly(ethylene oxide) (PEO), BaTiO3 as a ceramic filler, LiN(CF3SO2)2 as a lithium salt, and HBP as a plasticizer were investigated. The difference in the molecular weights of the HBP did not affect significantly the ionic conductivity. However, molecular weight distribution of the HBP might affect the ionic conductivity of the composite polymer electrolyte, which decreased with broadening of the molecular weight distribution. Further branching at the chain-end structure in the HBP led to a decrease in the ionic conductivity. The HBP with a longer EO chain length was effective to an enhancement of the ionic conductivity.

2004-11-30

254

BIOAFFINITY SENSORS BASED ON CONDUCTING POLYMERS: A SHORT REVIEW. (R825323)  

Science.gov (United States)

The development of new electrode materials has expanded the range and classes of detectable compounds using electroanalytical methods. Conducting electroactive polymers (CEPs) have been demonstrated to have remarkable sensing applications through their ability to be reversibly ox...

255

Transdutores potenciométricos a base de polímeros condutores: aplicações analíticas Potentiometric transducers based in conducting polymers: analytical applications  

Directory of Open Access Journals (Sweden)

Full Text Available A review is given about the most relevant advances on the analytical applications of conducting polymers in potentiometric sensors. These organic polymers represent a new class of materials with conducting properties due to its doping by ions. Several polymers already were synthesized such as polypyrrole, polyaniline, polythiophene, among others. Particular attention is devoted to the main advantages supplied by ion selective electrodes and gas sensors using conducting polymers, as well as the incorporation of bioactive elements in these polymers for the construction of biosensors. The correlation between structure, stability and ability to ion exchange of some conducting polymers applied as potentiometric transducers, is discussed.

Laércio Rover Júnior; Graciliano de Oliveira Neto; Lauro Tatsuo Kubota

1997-01-01

256

Study of charge transport in highly conducting polymers based on a random resistor network  

Energy Technology Data Exchange (ETDEWEB)

Based on a random resistor network (RRN), we study the unusual ac conductivity {sigma}({omega}) of highly conducting polymer such as PF{sub 6} doped polypyrrole. The system is modeled as a composite medium consisting of metallic regions randomly distributed in the amorphous parts. Within the metallic regions, the polymer chains are regularly and densely packed, outside which the poorly arranged chains form amorphous host. The metallic grains are connected by resonance quantum tunneling, which occurs through the strongly localized states in the amorphous media. {sigma}({omega}), calculated from this model, reproduces the main experimental features associated with the metal-insulator transition in these polymers.

Zhou Liping [Department of Physics, Suzhou University, Suzhou 215006 (China)]. E-mail: lipichow@hotmail.com; Liu Bo [Department of Physics, Suzhou University, Suzhou 215006 (China); Department of Physics, Jiangsu Teachers University of Technology, Changzhou 213001 (China); Li Zhenya [CCAST (World Laboratory), P.O. Box 8730, Beijing 100080 (China) and Department of Physics, Suzhou University, Suzhou 215006 (China)]. E-mail: zyli@suda.edu.cn

2004-12-06

257

Conducting Ni nanoparticles in an ion-modified polymer  

Science.gov (United States)

Conductive-atomic force microscopy has been used to perform nanoscale current imaging of Ni-ion-implanted polythylene terephthlate films. A reduction in bulk sheet resistivity, as the Ni dose is increased, is found to be accompanied by an evolution in local conductivity from a spatially homogeneous insulator to an interconnected network of conducting Ni crystallites. The crystallites have a mean dimension of 12.3 nm, confirmed by x-ray-diffraction analysis.

Sze, J. Y.; Tay, B. K.; Pakes, C. I.; Jamieson, D. N.; Prawer, S.

2005-09-01

258

Conducting Ni nanoparticles in an ion-modified polymer  

International Nuclear Information System (INIS)

[en] Conductive-atomic force microscopy has been used to perform nanoscale current imaging of Ni-ion-implanted polythylene terephthlate films. A reduction in bulk sheet resistivity, as the Ni dose is increased, is found to be accompanied by an evolution in local conductivity from a spatially homogeneous insulator to an interconnected network of conducting Ni crystallites. The crystallites have a mean dimension of 12.3 nm, confirmed by x-ray-diffraction analysis

2005-09-15

259

The removal of precious metals by conductive polymer filtration  

Energy Technology Data Exchange (ETDEWEB)

The growing demand for platinum-group metals (PGM) within the DOE complex and in industry, the need for modern and clean processes, and the increasing volume of low-grade material for secondary PGM recovery has a direct impact on the industrial practice of recovering and refining precious metals. There is a tremendous need for advanced metal ion recovery and waste minimization techniques, since the currently used method of precipitation-dissolution is inadequate. Los Alamos has an integrated program in ligand-design and separations chemistry which has developed and evaluated a series of water- soluble metal-binding polymers for recovering actinides and toxic metals from variety of process streams. A natural extension of this work is to fabricate these metal-selective polymers into membrane based separation unites, i.e., hollow-fiber membranes. In the present investigation, the material for a novel hollow-fiber membrane is characterized and its selectivity for PGM reported. Energy and waste savings and economic competitiveness are also described.

Cournoyer, M.E.

1996-10-01

260

UV cross-linked, lithium-conducting ternary polymer electrolytes containing ionic liquids  

Energy Technology Data Exchange (ETDEWEB)

In this manuscript is reported an attempt to prepare high ionic conductivity lithium polymer electrolytes by UV cross-linking the poly(ethyleneoxide) (briefly called PEO) polymer matrix in presence of the plasticizing lithium salt, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and an ionic liquid of the pyrrolidinium family (N-alkyl-N-methylpyrrolidinium TFSI) having a common anion with the lithium salt. It is demonstrated that polymer electrolytes with room temperature ionic conductivities of nearly 10{sup -3} S cm{sup -1} could be obtained as a result of the reduced crystallinity of the ternary electrolytes. The results clearly indicate that the cross-linked ternary electrolyte shows superior mechanical properties with respect to the non-cross-linked electrolytes and higher conductivities with respect to polymer electrolytes containing none or less ionic liquid. (author)

Kim, G.T.; Appetecchi, G.B.; Carewska, M. [ENEA, IDROCOMB, Casaccia Research Center, Via Anguillarese 301, 00123 Rome (Italy); Joost, M.; Balducci, A.; Winter, M. [Institute of Physical Chemistry, University of Muenster, Corrensstr. 28/30, D 48149 Muenster (Germany); Passerini, S. [ENEA, IDROCOMB, Casaccia Research Center, Via Anguillarese 301, 00123 Rome (Italy); Institute of Physical Chemistry, University of Muenster, Corrensstr. 28/30, D 48149 Muenster (Germany)

2010-09-15

 
 
 
 
261

A Route for Polymer Nanocomposites with Engineered Electrical Conductivity and Percolation Threshold  

Directory of Open Access Journals (Sweden)

Full Text Available Polymer nanocomposites with engineered electrical properties can be made by tuning the fabrication method, processing conditions and filler’s geometric and physical properties. This work focuses on investigating the effect of filler’s geometry (aspect ratio and shape), intrinsic electrical conductivity, alignment and dispersion within the polymer, and polymer crystallinity, on the percolation threshold and electrical conductivity of polypropylene based nanocomposites. The conductive reinforcements used are exfoliated graphite nanoplatelets, carbon black, vapor grown carbon fibers and polyacrylonitrile carbon fibers. The composites are made using melt mixing followed by injection molding. A coating method is also employed to improve the nanofiller’s dispersion within the polymer and compression molding is used to alter the nanofiller’s alignment.

Kyriaki Kalaitzidou; Hiroyuki Fukushima; Lawrence T. Drzal

2010-01-01

262

Carboxyl methylcellulose solid polymer electrolytes: Ionic conductivity and dielectric study  

Directory of Open Access Journals (Sweden)

Full Text Available The electrical conductivity and thermal conductivity of carboxyl methylcellulose and oleic acid have been measured by the electrical impedance spectroscopy method in the temperature range of 303 – 393 K. The composition of oleic acid was varied between 0 and 30 wt. % and the samples were prepared via solution casting technique. The highest ionic conductivity at room temperature, ?rt (303K) is 2.11 x 10-5 S cm-1 for sample containing 20 wt. % of oleic acid. The system was found to obey Arrhenius rule where R2 ? 1. The dielectric study (?^*, M^*) shows a non-Debye behavior. The activation energy of relaxation is higher than the activation energy of conduction implies that the charge carrier has to overcome the higher energy barrier during conducting.

Mohd Ikmar Nizam Mohamad Isa

2011-01-01

263

Superior thermal conductivity of polymer nanocomposites by using graphene and boron nitride as fillers  

Science.gov (United States)

We report a significant enhancement of thermal conductivity in polymer nanocomposites with graphene and boron nitride as fillers. Strong variations in the Raman spectra for different single-layer graphene flakes are related to the measured thermal conductivity in polymer nanocomposites. In the absence of doping, variations in the Raman parameters are most common, suggesting the presence of excess charges in the samples. Graphene has a Raman D-peak that indicates structural disorder is present, causing the large variations in Raman G peaks. Using this type of graphene and boron nitride for preparing the polymer nanocomposites, the thermal conductivities of the polymer nanocomposites are measured to be in the range of 6.2–9.5 W/mK. The absence of Raman D peaks suggests that structural defects are infinitesimal and the graphene is pristine. Polymer nanocomposites filled with graphene without a D-peak exhibit thermal conductivities as high as ˜21.6 W/mK. As a thermal management material, thermal imaging shows that the polymer nanocomposite can effectively lower the surface mounted LED temperature by 21.1 °C. The existence of Raman D peaks can be used to distinguish two different types of graphenes, establishing the primary prerequisite for achieving a higher thermal conductivity.

Liem, H.; Choy, H. S.

2013-06-01

264

Microcontact printing for patterning carbon nanotube/polymer composite films with electrical conductivity.  

Science.gov (United States)

Patterned carbon nanotube (CNT)/acrylic resin composite films were prepared using microcontact printing (?CP). To prepare ink for ?CP, CNTs were dispersed into propylene glycol monomethyl ether acetate (PGMEA) solution in which acrylic resin and a commercially available dispersant (Disperbyk-2001) dissolved. The resulting ink were spin-coated onto poly(dimethylsiloxane) (PDMS) stamps. By drying solvent components from the ink, CNT/polymer composite films were prepared over PDMS stamps. Contact between the stamps and glass substrates provided CNT/polymer composite patternings on the substrates. The transfer behavior of the CNT/polymer composite films depended on the thermal-treatment temperature during ?CP; thermal treatment at temperatures near the glass-transition temperature (T(g)) of the acrylic resin was effective to form uniform patternings on substrates. Moreover, contact area between polymer and substrates also affect the transfer behavior. The CNT/polymer composite films showed high electrical conductivity, despite the nonconductivity of polymer components, because CNTs in the films were interconnected. The electrical conductivity of the composite films increased as CNT content in the film became higher; as a result, the composite patternings showed almost as high electrical conductivity as previously reported CNT/polymer bulk composites. PMID:22900673

Ogihara, Hitoshi; Kibayashi, Hiro; Saji, Tetsuo

2012-08-28

265

Microcontact printing for patterning carbon nanotube/polymer composite films with electrical conductivity.  

UK PubMed Central (United Kingdom)

Patterned carbon nanotube (CNT)/acrylic resin composite films were prepared using microcontact printing (?CP). To prepare ink for ?CP, CNTs were dispersed into propylene glycol monomethyl ether acetate (PGMEA) solution in which acrylic resin and a commercially available dispersant (Disperbyk-2001) dissolved. The resulting ink were spin-coated onto poly(dimethylsiloxane) (PDMS) stamps. By drying solvent components from the ink, CNT/polymer composite films were prepared over PDMS stamps. Contact between the stamps and glass substrates provided CNT/polymer composite patternings on the substrates. The transfer behavior of the CNT/polymer composite films depended on the thermal-treatment temperature during ?CP; thermal treatment at temperatures near the glass-transition temperature (T(g)) of the acrylic resin was effective to form uniform patternings on substrates. Moreover, contact area between polymer and substrates also affect the transfer behavior. The CNT/polymer composite films showed high electrical conductivity, despite the nonconductivity of polymer components, because CNTs in the films were interconnected. The electrical conductivity of the composite films increased as CNT content in the film became higher; as a result, the composite patternings showed almost as high electrical conductivity as previously reported CNT/polymer bulk composites.

Ogihara H; Kibayashi H; Saji T

2012-09-01

266

Direct current conductivity of carbon nanofiber-based conductive polymer composites: effects of temperature and electric field.  

Science.gov (United States)

Polymer composites based on high density polyethylene (HDPE) and carbon nanofiber (CNF) were fabricated by melt compounding. The dependences of electrical conductivity of HDPE-CNF composites on filler concentration, temperature, and applied electric field were investigated. The results showed that the conductivity of the HDPE-CNF composites follows the scaling law of percolation theory. Increasing temperature caused a sharp increase in the resistivity of HDPE-CNF composites near the melting temperature of HDPE, yielding a positive temperature coefficient (PTC) effect of resistance. The potential mechanisms involved in the PTC effect of such composites were analyzed. An investigation of the effect of electric field on the conductivity of HDPE-CNF composites revealed the presence of tunneling conduction. The tunneling conductivity increased with increasing filler content because of high tunneling frequency, and decreased with rising temperature as a result of gap widening between conducting CNF fillers. PMID:21780386

He, Lin Xiang; Tjong, Sie Chin

2011-05-01

267

Direct current conductivity of carbon nanofiber-based conductive polymer composites: effects of temperature and electric field.  

UK PubMed Central (United Kingdom)

Polymer composites based on high density polyethylene (HDPE) and carbon nanofiber (CNF) were fabricated by melt compounding. The dependences of electrical conductivity of HDPE-CNF composites on filler concentration, temperature, and applied electric field were investigated. The results showed that the conductivity of the HDPE-CNF composites follows the scaling law of percolation theory. Increasing temperature caused a sharp increase in the resistivity of HDPE-CNF composites near the melting temperature of HDPE, yielding a positive temperature coefficient (PTC) effect of resistance. The potential mechanisms involved in the PTC effect of such composites were analyzed. An investigation of the effect of electric field on the conductivity of HDPE-CNF composites revealed the presence of tunneling conduction. The tunneling conductivity increased with increasing filler content because of high tunneling frequency, and decreased with rising temperature as a result of gap widening between conducting CNF fillers.

He LX; Tjong SC

2011-05-01

268

Nanocrystal quantum dots  

CERN Multimedia

Showing advancements in colloidal nanocrystals and quantum-confined nanostructures, this title focuses on the semiconductor nanocrystals known as nanocrystal quantum dots. This title includes chapters on carrier multiplication, doping of semiconductor nanocrystals, and applications of nanocrystals in biology.

Klimov, Victor I

2010-01-01

269

Effective Thermal Conductivity of Polymer Composites Using Local Fractal Techniques  

Directory of Open Access Journals (Sweden)

Full Text Available The model developed by Springer and Tsai is extended using non-linear volume fraction in place of physical porosity for the effective thermal conductivity of composite materials with the help of local fractal techniques. The expression for non-linear volume fraction is obtained using data available in the literature. Present model is constructed in terms of fiber volume fraction, the fiber-matrix thermal conductivity ratio and the local fractal dimensions. The effective thermal conductivity ratio is evaluated using the model with the approximation of the fractal dimensions. These fractal dimensions [PdandTd] are considered to be equal in the absence of information about the arrangement of fibers in the composites. The technique of local fractal dimensions is used to reduce the geometric complexity of the fiber arrangements. Better agreement of predicted effective thermal conductivity values with experimental results is obtained. A comparison with other models is also done and found that our model predict the values of effective thermal conductivity quite well.

Rajpal Singh Bhoopal,; P. K. Sharma,; Ramvir Singh,; Sajjan Kumar,

2013-01-01

270

Low polymer hydraulic fracturing applications in Reconcavo basin wells can reduce cost and improve conductivity  

International Nuclear Information System (INIS)

[en] Gels used for hydraulic-fracturing treatments generally contain high concentrations of polymer. The polymer helps the fracturing fluid achieve the level of viscosity necessary for transporting proppant through the rock matrix. However, high-polymer gels leave greater amounts of residue in the formation and can therefore cause formation damage. This paper describes how low polymer (L P) gels can be used for hydraulic-fracturing operations to reduce job costs and increase conductivity by reducing formation damage while maintaining the characteristics of a high-polymer gel. The L P fluid system has a low p H and contains an appropriate breaker concentration. Operators have achieved positive results with this system, which allows them to measure robust gel breaks and reduces the necessity for well cleaning. Consequently, formation damage can be significantly reduced. (author)

2000-01-01

271

Exploring novel silicon-containing polymers---From preceramic polymers to conducting polymers with nonlinear optical properties  

Energy Technology Data Exchange (ETDEWEB)

Several new types of silicon-containing preceramic polymers, i.e., poly(diorganosilacetylene) and poly(diorganosilvinylene) have been synthesized with molecular weights from 10,000 to 120,000. These polymers could be thermally converted to SiC with a moderate to high char yields. Ready solubility and good processability made these types of polymers attractive in their applications to ceramics. The thermal polymerization of diethynyldiphenyl-silane, which was reported in 1968 to afford poly(diphenylsilyldiacetylene) via dehydrogenation, was reinvestigated. Spectroscopic studies showed that the polymer had a structure of polyacetylene type not diacetylene. Diphenyldiethynylgermane and a series of diorganodiethynylsilances were synthesized. These could be polymerized in the presence of MoCl{sub 5} or WCl{sub 6} to afford a soluble, violet material with Mw as high as 108,000. 100 refs., 56 figs., 16 tabs.

Pang, Yi.

1991-10-07

272

Thermally degradable ligands for nanocrystals.  

UK PubMed Central (United Kingdom)

We exchanged the oleate ligands on as-prepared PbSe/CdSe core/shell nanocrystals with octyldithiocarbamate to enable the removal of insulating ligands by gentle heating. The octyldithiocarbamate ligand could readily be stripped from the surface by heating briefly to temperatures from 140 to 205 degrees C, which is substantially lower than the temperature (330 degrees C) required to remove oleate from the nanocrystal surface. X-ray diffraction and transmission electron microscopy reveal that the nanocrystals sinter around 250 degrees C, resulting in a loss of quantum confinement. Heating for 1 min to 205 degrees C removed 92% of the organics from the surface. We could therefore prepare densely packed films of quantum-confined nanocrystals via dithiocarbamate treatment. Conductivity increased by up to 4 orders of magnitude after annealing. In addition to PbSe/CdSe core/shell nanocrystals, we also examined the applicability of our ligand removal procedure to CdSe nanocrystals.

Wills AW; Kang MS; Khare A; Gladfelter WL; Norris DJ

2010-08-01

273

One-step inkjet printing of conductive silver tracks on polymer substrates  

Energy Technology Data Exchange (ETDEWEB)

A one-step process to fabricate conductive features on flexible polymer substrates by inkjet printing an organometallic silver ink directly onto a substrate that is heated to 130 deg. C is presented. This process led to the immediate sintering of the printed features. The samples were left for 5 min at elevated temperature, which resulted in conductive silver features with a resistivity of eight times the bulk silver value. The combination of this ink and the simultaneous printing/sintering process opens up routes for the direct fabrication of conductive features on common polymer substrates that could be applied, for example, in roll-to-roll production of flexible microelectronic systems.

Perelaer, Jolke; Hendriks, Chris E; Schubert, Ulrich S [Laboratory of Macromolecular Chemistry and Nanoscience, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven (Netherlands); De Laat, Antonius W M [Philips Applied Technologies, High Tech Campus 7-3A-022-3, 5656 AE Eindhoven (Netherlands)], E-mail: u.s.schubert@tue.nl

2009-04-22

274

Molecular hybrid materials based on conducting organic polymers and electroactive/photoactive inorganic species  

Energy Technology Data Exchange (ETDEWEB)

Synthesis and electrochemical properties of a new class of hybrid organic-inorganic materials formed by a matrix of conducting organic polymers and inorganic electroactive species dispersed in it at a molecular level, and their application as electrodes for energy storage and conversion are discussed. The resulting hybrids retain the good conductivity and plastic nature of the organic matrix while adding the specific activity of the inorganic component. Examples of various combinations are described to illustrate how the incorporation of photoactive anions such as the polyoxometalates into conducting organic polymers can yield hybrids with interesting photophysical and photocatalytic properties. 22 refs., 4 figs.

Torres-Gomez, G.; Lira-Cantu, M.; Gomez-Romero, P. [Institut de Ciencia de Materials de Barcelona (Spain)

1999-04-01

275

Sulfonated polyaniline, a conducting polymer electrode for ion transfer batteries  

Energy Technology Data Exchange (ETDEWEB)

Sulfonated polyaniline (SPAN) was synthesized by sulfonation of polyaniline base with f6ming sulfuric acid. The polymer films were characterized by XPS, FFIR and UV-vis-NIR. XPS in combination with FTIR shows that the preparation procedure leads to a ca. 47% sulfonation of an otherwise unchanged polyaniline backbone. Electrodes modified with SPAN films exhibited two redox steps in aqueous as well as in nonaqueous electrolytes. Probe Beam Deflection and Quartz Crystal Microbalance were used to study the ion exchange mechanism. Protons are predominantly expelled during the first and second oxidation steps in acidic aqueous solution, accompanied by a counterflux of solvent. In nonaqueous electrolyte, expulsion of cations seems to be the dominant flux during SPAN oxidation, while solvent counterflux plays a significant role. The specific charge of SPAN films was found to be ca. 37 Ah/kg in aqueous solution (only first redox process used) and ca. 68 Ah/kg in nonaqueous media (both redox processes). Based on their experimental results, an estimation for a practical SPAN/Li battery would have 50% more specific energy than a PANI/Li one.

Barbero, C.; Miras, M.C.; Koetz, R.; Haas, O. [Paul Scherrer Inst., Villigen (Switzerland). Electrochemistry Section

1994-12-31

276

Transdutores potenciométricos a base de polímeros condutores: aplicações analíticas/ Potentiometric transducers based in conducting polymers: analytical applications  

Scientific Electronic Library Online (English)

Full Text Available Abstract in english A review is given about the most relevant advances on the analytical applications of conducting polymers in potentiometric sensors. These organic polymers represent a new class of materials with conducting properties due to its doping by ions. Several polymers already were synthesized such as polypyrrole, polyaniline, polythiophene, among others. Particular attention is devoted to the main advantages supplied by ion selective electrodes and gas sensors using conducting po (more) lymers, as well as the incorporation of bioactive elements in these polymers for the construction of biosensors. The correlation between structure, stability and ability to ion exchange of some conducting polymers applied as potentiometric transducers, is discussed.

Rover Júnior, Laércio; Oliveira Neto, Graciliano de; Kubota, Lauro Tatsuo

1997-10-01

277

D. c. electrical transport in a new conducting polymer: oxidized poly(N-vinylpyrrole)  

Energy Technology Data Exchange (ETDEWEB)

D.c. electrical transport properties of pellets of oxidized poly(N-vinylpyrrole), a new conducting ladder polymer, are studied. D.c. conductivity data are coherent with a three-dimensional variable range hopping transport model. Relevant microscopic parameters of the model are inferred from data and are briefly discussed. (orig.).

Cagnolati, R.; Lucchesi, M.; Rolla, P.A. (Dipt. di Fisica, Consorzio Interuniversitario di Fisica della Materia, Pisa (Italy)); Castelvetro, V. (Dipt. di Chimica e Chimica Industriale, Univ. di Pisa (Italy) ENI/Scuola Normale Superiore, Pisa (Italy)); Ciardelli, F. (Dipt. di Chimica e Chimica Industriale, Univ. di Pisa (Italy)); Colligiani, A. (Dipt. di Chimica e Chimica Industriale, Univ. di Pisa (Italy) Dipt. di Chimica Industriale, Univ. di Messina (Italy))

1992-01-01

278

Mixed ionic and electronic conductivity in polymers. Progress report, January 1, 1990--December 31, 1990  

Energy Technology Data Exchange (ETDEWEB)

New polymer films were synthesized that are mixed ionic-electronic conductors. Preliminary ion transport measurements have been made on these materials in the reduced state where electronic conductivity is negligible. We also have made preliminary measurements of switching times for these materials. Theoretical studies have been performed ion pairing in insulating and electronically conducting films.

Shriver, D.F.

1991-06-01

279

Structure-conductivity studies in polymer electrolytes containing multivalent cations  

CERN Multimedia

force microscopy (AFM). DSC evidences helped to explain the texture of the iron samples during the drying process, and showed transitions between low melting, PEO and high melting spherulites, and VTPM is able to visualise the spherulites present in the samples. AFM has successfully imaged the as cast PEO sub 8 :FeBr sub 2 sample and the surface effect causing extra resistance in the impedance spectra could be seen. Conductivity studies were carried out using a.c. impedance spectra. Fe(ll) samples exhibit the typical semicircle-spike plot but the Fe(lll) samples displayed an extra semicircle before the spike reflecting a surface effect. This is also manifested in the Arrhenius plots of the same samples where a dip was shown at 100 deg C. From the conductivity studies on the iron systems it was found that for the dry samples the optimum conductivity was observed in PEO sub 8 :FeBr sub x irrespective of the valence state of the cation. For the air-cast samples the optimum conductivity composition depends on the...

Aziz, M

1996-01-01

280

Sensing of environmental pollutant by conductive composite from prepared from hyperbranched polymer-grafted carbon black and crystalline polymer  

International Nuclear Information System (INIS)

[en] Complete text of publication follows. The hyperbranched (HB) polymer-grafted (PG) carbon blacks (CB) have the possibility of utilizing as a support of catalyst and enzyme, and a curing agent of epoxy resin, because they have much terminal amino or hydroxyl groups. The postgrafting of crystalline polymer onto HB PG CB and the sensing of environmental pollutant by the conductive composite prepared from the polymer-postgrafted CB was discussed. The grafting of poly(amidoamide) onto CB surface was achieved by repeating either Michael addition of methyl acrylate to amino group on the surface or the amidation of the resulting terminal methyl ester group with ethylene diamine. HB polyester onto CB surface was grafted by stepwise growth of 2,2-bis(hydroxymethyl)propionic acid (bis-MPA) from surface carboxyl and hydroxyl groups on CB as a core in the presence of p-toluenesulfonic acid (p-TSA). The one-pot grafting of HB polyester onto CB as core was also achieved by the polycondensation of bis-MPA in the presence of p-TSA. Postgrafting of crystalline polymer onto HB polymer-grafted CB was achieved by the reaction of terminal amino or hydroxyl groups of grafted chain with COCl-terminated crystalline polymer. The electric resistance of the composite prepared from crystalline polymer-postgrafted CB was found to increase drastically in hexane, containing environmental pollutant, such as chloroform and trichloroethane, and returned immediately to the initial resistance when it was transferred into pure hexane. Based on the above results, it is concluded that the composite can be used as a novel sensor for environmental pollutant in solution

2002-09-05

 
 
 
 
281

Spectroscopic studies of the novel conducting polymer polytetrafluorobenzo-c-thiophene  

Energy Technology Data Exchange (ETDEWEB)

Tetra-fluorinated benzo-c-thiophene (or Isothianaphthalene) polymer of length distributed about 40 monomer units was studied over a wide range of oxidation levels using UV-visible-NIR and ESR spectroscopy. This soluble polymer proves to be a model system for the study of charged species on conducting polymers, free from the complications of branching, bulk confinement or inter chain interaction. Charging the oligomers can be seen to take place with carriers ranging between isolated radical cations (polarons) and interacting dicationic species (bipolarons). (orig.)

Swann, M.J. (Dept. of Physics, Durham Univ. (United Kingdom)); Bloor, D. (Dept. of Physics, Durham Univ. (United Kingdom)); Brooke, G. (Dept. of Chemistry, Durham Univ. (United Kingdom)); Maher, J. (Dept. of Chemistry, Univ. of Bristol, Cantocks Close (United Kingdom))

1993-03-15

282

Investigation of the electronic properties and morphology of conducting polymer electrodes for engineering applications  

Energy Technology Data Exchange (ETDEWEB)

We evaluate the performance of the conducting polymers, polyaniline (PAni) and poly-3-(4-fluorophenyl)-thiophene (PFPT), as the active material in electrochemical capacitors. Using scanning electron microscopy and cyclic voltammetry, the morphology and charge/discharge characteristics of the as-grown polymers were studied under different electrochemical conditions. When electropolymerized at high current densities in aqueous acid solution, PAni exhibits a morphology consisting of a network of interwoven fibrils. It was shown that layers of this PAni network can be electropolymerized onto a thin-planar metal substrate resulting in a decrease in cathodic and anodic peak separations, improving charge/discharge reversibility. A continuous PAni network will make possible a decreases in the total weight of the electrodes with respect to those electrodes grown onto a fibrous carbon substrate of high surface area and high porosity. The effect of different growth electrolytes on the charge/discharge process was also characterized. Hydrochloric acid electrolyte provided an optimum polymer deposition, with respect to morphology and capacitive performance. PFPT films were grown from a solution in a non-aqueous solution. High growth current densities affected the performance of PFPT polymer films in a positive manner. A growth rate of 20 mA/cm{sup 2} not only provided an increase in charge storage, but in the amount of polymer deposited when compared to equivalent amounts deposited at 1 mA/cm{sup 2}. The morphology of the deposited conducting polymer is shown to be one of the most important characteristics in the attempt to achieve an ideal electrochemical capacitor electrode. The polymer morphology directly affects the charge/discharge process because of the strong interaction between ionic conductivity in the electrolyte and the electronic conductivity of the polymer. Cyclic-dependent degradation of the PFPT films was observed.

Landeros, J. Jr.; Pizzo, P.; Cantow, M. [San Jose State Univ., CA (United States). Dept. of Materials Engineering; Uribe, F. [Los Alamos National Lab., NM (United States)

1995-02-01

283

Mixed-ionic and electronic conductivity in polymers. Annual technical progress report  

Energy Technology Data Exchange (ETDEWEB)

The aim in this portion of the research is to prepare new electroactive films with high ion mobility, and to characterize the transport properties of these materials. The classic conducting polymers, polyacetylene, polythiophene, and polypyrrole have dense structures that prevent rapid redox switching because of the low diffusivity of ions. The objective is to modify the last two polymers with pendant polyethers, which should greatly improve ion transport.

Ratner, M.A.; Shriver, D.F.

1991-12-31

284

Application for continuation of mixed ionic and electronic conductivity in polymers  

Energy Technology Data Exchange (ETDEWEB)

The aim in this portion of the research is to prepare new electroactive films with high ion mobility, and to characterize the transport properties of these materials. The classic conducting polymers, polyacetylene, polythiophene, and polypyrrole have dense structures that prevent rapid redox switching because of the low diffusivity of ions. The objective is to modify the last two polymers with pendant polyethers, which should greatly improve ion transport.

Shiver, D.F.; Ratner, M.A.

1990-01-01

285

Electrochemical characterisation of the polymer/solution interface for electronically conducting and conventional redox-polymers  

Energy Technology Data Exchange (ETDEWEB)

A striking difference between the kinetics of hydroquinone/p-benzoquinone redox-couple reaction on polyaniline and poly-o-phenylenediamine coated electrodes has been observed and explained in terms of the difference in equilibrium potential distribution across the polymer/solution interfaces. (orig.)

Levi, M.D. (A.N. Frumkin Inst. of Electrochemistry, Moscow (Russian Federation)); Pisarevskaya, E.Yu. (A.N. Frumkin Inst. of Electrochemistry, Moscow (Russian Federation))

1993-03-22

286

Formation of Wigner crystals in conducting polymer nanowires  

CERN Document Server

The search for theoretically predicted Wigner crystal in one-dimensional (1D) wires of structurally disordered materials exhibiting properties of charge-density-waves have remained unsuccessful. Based on the results of a low temperature conductivity study we report here formation of such 1D Wigner crystal (1DWC) in polypyrrole nanowires having low electron densities. The current-voltage characteristics of all the nanowires show a 'gap' that decreases rapidly as the temperature is increased - confirming the existence of long-range electron-electron interaction in the nanowires. The measured current show power-law dependence on voltage and temperature as expected in 1DWC. A switching transition to highly conducting state has been observed above a threshold voltage, which can be tuned by changing the diameters of the nanowires and the temperature. Negative differential resistance and enhancement of noise has been observed above the threshold as expected.

Rahman, A; Rahman, Atikur; Sanyal, Milan K.

2007-01-01

287

Ion and molecule sensors using molecular recognition in luminescent, conductive polymers. 1998 annual progress report  

Energy Technology Data Exchange (ETDEWEB)

'The purpose of this project is to develop sensor technology for detecting specific heavy metal ions, such as transition metals, lead, lanthanides, and actinides in waste streams. The sensing strategy uses molecular recognition of the metal ions by polymers that change their luminescence and conductivity properties upon metal binding. Research problems that are being addressed by this project include: (1) designing molecular recognition sites that are highly selective for the metal ions of interest in the presence of a large background of other chemical species, (2) finding ways to incorporate many different selective groups into a single polymer, (3) fabricating polymer films, strips, sheets, and coatings that can be applied to other materials, such as fiber optics and surfaces, (4) developing interfaces between the polymers and substrates that can be used to produce prototype arrays of many sensor elements for rapid multi-contaminant detection and quantitation, and (5) developing multiplexed data collection techniques to rapidly process the data obtained from many polymer sensors into a chemical profile of a waste stream or waste site in real time. As of June 1, 1998, the authors have prepared several polymers based on the incorporation of 2,2{prime}-bipyridine into poly(phenylenevinylene) polymers. The central idea, illustrated in Figure 1, is to prepare a pseudoconjugated, ligand-containing polymer that upon incorporating metal ions undergoes a conformational change, thus converting the initial partially conjugated polymer to a fully or near fully conjugated one. Such conjugation enhancement,along with the simultaneous electron density change caused by incorporating metal ions onto the backbone of polymers, dramatically changes the optical and conductivity properties of the polymer. These property changes are used to signal the presence of the metal ion analyte. The authors have developed several synthetic routes to these polymers and have demonstrated that they exhibit selective binding properties when exposed to transition metals and lanthanides. In addition, the authors have developed a new polymer that gives us the versatility that they need for rapid attachment of ligands that bind heavy metals, such as lead and plutonium.'

Wasielewski, M.R. [Argonne National Lab., IL (US). Chemistry Div.; Raymond, K. [Univ. of California, Berkeley, CA (US). Dept. of Chemistry; Walt, D.E. [Tufts Univ., Medford, MA (US). Dept. of Chemistry

1998-06-01

288

Neuronal differentiation of embryonic stem cell derived neuronal progenitors can be regulated by stretchable conducting polymers.  

UK PubMed Central (United Kingdom)

Electrically conducting polymers are prospective candidates as active substrates for the development of neuroprosthetic devices. The utility of these substrates for promoting differentiation of embryonic stem cells paves viable routes for regenerative medicine. Here, we have tuned the electrical and mechanical cues provided to the embryonic stem cells during differentiation by precisely straining the conducting polymer (CP) coated, elastomeric-substrate. Upon straining the substrates, the neural differentiation pattern occurs in form of aggregates, accompanied by a gradient where substrate interface reveals a higher degree of differentiation. The CP domains align under linear stress along with the formation of local defect patterns leading to disruption of actin cytoskeleton of cells, and can provide a mechano-transductive basis for the observed changes in the differentiation. Our results demonstrate that along with biochemical and mechanical cues, conductivity of the polymer plays a major role in cellular differentiation thereby providing another control feature to modulate the differentiation and proliferation of stem cells.

Srivastava N; Venugopalan V; Divya MS; Rasheed VA; James J; Narayan KS

2013-09-01

289

Neuronal differentiation of embryonic stem cell derived neuronal progenitors can be regulated by stretchable conducting polymers.  

Science.gov (United States)

Electrically conducting polymers are prospective candidates as active substrates for the development of neuroprosthetic devices. The utility of these substrates for promoting differentiation of embryonic stem cells paves viable routes for regenerative medicine. Here, we have tuned the electrical and mechanical cues provided to the embryonic stem cells during differentiation by precisely straining the conducting polymer (CP) coated, elastomeric-substrate. Upon straining the substrates, the neural differentiation pattern occurs in form of aggregates, accompanied by a gradient where substrate interface reveals a higher degree of differentiation. The CP domains align under linear stress along with the formation of local defect patterns leading to disruption of actin cytoskeleton of cells, and can provide a mechano-transductive basis for the observed changes in the differentiation. Our results demonstrate that along with biochemical and mechanical cues, conductivity of the polymer plays a major role in cellular differentiation thereby providing another control feature to modulate the differentiation and proliferation of stem cells. PMID:23544950

Srivastava, Nishit; Venugopalan, Vijay; Divya, M S; Rasheed, V A; James, Jackson; Narayan, K S

2013-05-14

290

Structural, thermal and ion transport properties of radiation grafted lithium conductive polymer electrolytes  

International Nuclear Information System (INIS)

[en] Structural, thermal and ion transport properties of lithium conductive polymer electrolytes prepared by radiation-induced grafting of styrene onto poly(vinylidene fluoride) (PVDF) films and subsequent activation with LiPH6/EC/DEC liquid electrolyte were investigated in correlation with the content of the grafted polystyrene (Y%). The changes in the structure were studied using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). Thermal gravimetric analysis (TGA) was used to evaluate the thermal stability. The ionic conductivity was measured by means of ac impedance spectroscopy at various temperatures. The polymer electrolytes were found to undergo considerable structural and morphological changes that resulted in a noticeable increase in their ionic conductivity with the increase in Y% at various temperatures (25-65 deg. C). The ionic conductivity achieved a value of 1.61 x 10-3 S cm-1 when Y of the polymer electrolyte reached 50% and at 25 deg. C. The polymer electrolytes also showed a multi-step degradation behaviour and thermal stability up to 120 deg. C, which suits normal lithium battery operation temperature range. The overall results of this work suggest that the structural changes took place in PVDF matrix during the preparation of these polymer electrolytes have a strong impact on their various properties

2006-10-10

291

Corrosion protection of metals by conductive polymers III. Improved performance and inhibition in NaCl  

Energy Technology Data Exchange (ETDEWEB)

The use of conducting polymers for corrosion prevention is an area which has gained increasing attention during the last decade. This study explores the use of polyaniline based polymer coatings for corrosion prevention on mild steel. Data on coating degradation and passivation on electrochemically polarized painted metal specimens exposed to acid chloride solutions and artificial seawater at an ambient temperature are presented. A Systematic comparison between controls and designated coated sample sets has been made to demonstrate good corrosion protection efficiency with synergistic effects between conductive polymers and metals by classical DC monitoring techniques. Brief comparisons are made with data from simulated marine exposure. Meanwhile, in separate experiments, electrochemical data were obtained for conductive polymer primer coatings with epoxy top-coat under fully immersed conditions by using electrochemical noise (ECN) monitoring and scanning electrochemical microscopy (SECM) techniques to discover the initial localized corrosion phenomena in order to achieve further understanding of the protection mechanism. Additionally, electrochemical impedance (EIS) spectra were utilized for the assessment of anti-corrosion performance provided by conducting polymers to mild steel.

Lu, W.K.; Elsenbaumer, R.L.; Chen, T.; Kulkarni, V.G.

1998-07-01

292

Electron-donor dopant, method of improving conductivity of polymers by doping therewith, and a polymer so treated  

Energy Technology Data Exchange (ETDEWEB)

Polymers with conjugated backbones, both polyacetylene and polyaromatic heterocyclic types, are doped with electron-donor agents to increase their electrical conductivity. The electron-donor agents are either electride dopants made in the presence of lithium or dopants derived from alkalides made in the presence of lithium. The dopants also contain a metal such as cesium and a trapping agent such as a crown ether.

Liepins, Raimond (Los Alamos, NM); Aldissi, Mahmoud (Los Alamos, NM)

1988-01-01

293

Patterning of conducting polymer nanowires on gold/platinum electrodes  

International Nuclear Information System (INIS)

We demonstrate a technique for the patterning of conducting polyaniline nanowires on metallic substrates. Electrochemical synthesis of template-free polyaniline nanowires is initially preceded by the formation of a thin compact 2D layer, which we show spreads horizontally from the edge of a gold electrode across a SiO2 surface. This encumbers nanowire patterning during the fabrication of nanowire devices since it leads to electrical short-circuiting of the metal contacts before the nanowires have fully developed. In this paper we demonstrate the use of amine-terminated self-assembled monolayers, 3-aminopropyltriethoxysilane, to inhibit the spread of polyaniline growth onto adjacent SiO2 surfaces. The technique has important applications in the fabrication of nanowire devices and area-selective patterning of nanowires on metallic electrodes.

2007-04-11

294

Study of Swift Heavy Ion Modified Conducting Polymer Composites for Application as Gas Sensor  

Directory of Open Access Journals (Sweden)

Full Text Available A polyaniline-based conducting composite was prepared by oxidativepolymerisation of aniline in a polyvinylchloride (PVC) matrix. The coherent free standingthin films of the composite were prepared by a solution casting method. The polyvinylchloride-polyaniline composites exposed to 120 MeV ions of silicon with total ion fluenceranging from 1011 to 1013 ions/cm2, were observed to be more sensitive towards ammoniagas than the unirradiated composite. The response time of the irradiated composites wasobserved to be comparably shorter. We report for the first time the application of swiftheavy ion modified insulating polymer conducting polymer (IPCP) composites for sensingof ammonia gas.

Alok Srivastava; Virendra Singh; Chetna Dhand; Manindar Kaur; Tejvir Singh; Karin Witte; Ulrich W. Scherer

2006-01-01

295

A review study of (bio)sensor systems based on conducting polymers.  

Science.gov (United States)

This review article concentrates on the electrochemical biosensor systems with conducting polymers. The area of electro-active polymers confined to different electrode surfaces has attracted great attention. Polymer modified carbon substrate electrodes can be designed through polymer screening to provide tremendous improvements in sensitivity, selectivity, stability and reproducibility of the electrode response to detect a variety of analytes. The electro-active films have been used to entrap different enzymes and/or proteins at the electrode surface, but without obvious loss of their bioactivity for the development of biosensors. Electropolymerization is a well-known technique used to immobilize biomaterials to the modified electrode surface. Polymers might be covalently bonding to enzymes or proteins; therefore, thickness, permeation and charge transport characteristics of the polymeric films can be easily and precisely controlled by modulating the electrochemical parameters for various electrochemical techniques, such as chronoamperometry, chronopotentiometry, cyclic voltammetry, and differential pulse voltammetry. This review article is divided into three main parts as given in the table of contents related to the immobilization process of some important conducting polymers, polypyrrole, polythiophene, poly(3,4-ethylenedioxythiophene), polycarbazole, polyaniline, polyphenol, poly(o-phenylenediamine), polyacetylene, polyfuran and their derivatives. A total of 216 references are cited in this review article. The literature reviewed covers a 7 year period beginning from 2005. PMID:23498205

Ates, Murat

2013-01-24

296

A review study of (bio)sensor systems based on conducting polymers.  

UK PubMed Central (United Kingdom)

This review article concentrates on the electrochemical biosensor systems with conducting polymers. The area of electro-active polymers confined to different electrode surfaces has attracted great attention. Polymer modified carbon substrate electrodes can be designed through polymer screening to provide tremendous improvements in sensitivity, selectivity, stability and reproducibility of the electrode response to detect a variety of analytes. The electro-active films have been used to entrap different enzymes and/or proteins at the electrode surface, but without obvious loss of their bioactivity for the development of biosensors. Electropolymerization is a well-known technique used to immobilize biomaterials to the modified electrode surface. Polymers might be covalently bonding to enzymes or proteins; therefore, thickness, permeation and charge transport characteristics of the polymeric films can be easily and precisely controlled by modulating the electrochemical parameters for various electrochemical techniques, such as chronoamperometry, chronopotentiometry, cyclic voltammetry, and differential pulse voltammetry. This review article is divided into three main parts as given in the table of contents related to the immobilization process of some important conducting polymers, polypyrrole, polythiophene, poly(3,4-ethylenedioxythiophene), polycarbazole, polyaniline, polyphenol, poly(o-phenylenediamine), polyacetylene, polyfuran and their derivatives. A total of 216 references are cited in this review article. The literature reviewed covers a 7 year period beginning from 2005.

Ates M

2013-05-01

297

A new polymer cathode-conducting polymer interconnected with sulfur-sulfur bonds: Poly(2,2{prime}-dithiodianiline)  

Energy Technology Data Exchange (ETDEWEB)

Poly(2, 2{prime}-Dithiodianiline)(Poly)(DTDA), a conducting polymer having disulfide bond in it, has been proposed as a new class of high energy storage material. DTDA has one S-S bond interconnected between two moieties of anilines. The structure of the poly(DTDA) was similar to that of polyaniline in addition that the S-S bond is preserved after electropolymerization of DTDA. The poly(DTDA) has some advantages because of its high theoretical energy density, faster kinetics and higher electrical conductivity than other organosulfur cathodes.

Naoi, Katsuhiko; Kawase, Kenichi; Mori, Mitsuhiro; Komiyama, Michiko

1998-07-01

298

Microfluidic enhanced conductive polymer microspheres for sensor applications  

Science.gov (United States)

Methods and devices were developed to produce monodispersed, conducting, responsive polyaniline (PANI) particles for drug delivery and sensor applications. Liquid droplets are produced containing a dispersed phase carried through the device by the continuous phase. The two phases are immiscible. Each phase can be either oil or water based. The aniline monomer is contained within the dispersed phase while the oxidizing agent, ammonium persulfate (APS) is contained within the aqueous phase. The production of either solid (aniline, APS in dispersed phase) or shell particles (aniline in dispersed phase, APS in continuous phase) is possible. Droplets are formed by controlling the viscous and capillary forces at the interface. Droplet size is controlled by phase flow rates, the interfacial tension and viscosity ratio between the phases and the inlet geometry. PANI particles are produce via oxidative polymerization. The polymerization is pH dependent and the time of polymerization is monitored by the distance the droplets travel in the channel. The morphology and electrochemical characteristics of the particles resulting from these methods are studied.

Snyder, Jessica; Lu, Donglai; Shen, Amy

2010-11-01

299

Selective sensing of volatile organic compounds using novel conducting polymer-metal nanoparticle hybrids  

International Nuclear Information System (INIS)

Conducting polymer-metal nanoparticle hybrids, fabricated by assembling metal nanoparticles on top of functionalized conducting polymer film surfaces using conjugated linker molecules, enable the selective sensing of volatile organic compounds (VOCs). In these conducting polymer-metal nanoparticle hybrids, selectivity is achieved by assembling different metals on the same conducting polymer film. This eliminates the need to develop either different polymers chemistries or device configurations for each specific analyte. In the hybrids, chemisorption of the analyte vapor induces charge redistribution in the metal nanoparticles and changes their work function. The conjugated linker molecule causes this change in the work function of the tethered nanoparticles to affect the electronic states in the underlying conducting polymer film. The result is an easily measurable change in the resistance of the hybrid structure. The fabrication of these sensing elements involved the covalent assembly of nickel (Ni) and palladium (Pd) metal nanoparticles on top of poly(3,4-ethylenedioxythiophene-co-thiophene-3-acetic acid), poly(EDOT-co-TAA), films using 4-aminothiophenol linker molecules. The change in resistance of hybrid Pd/poly(EDOT-co-TAA) and Ni/poly(EDOT-co-TAA) hybrid films to acetone and toluene, respectively, is observed to be in proportion to their concentrations. The projected detection limits are 2 and 10 ppm for toluene and acetone, respectively. A negligible response (resistance change) of the Pd/poly(EDOT-co-TAA) films to toluene exposure confirmed its selectivity for detecting acetone. Similarly, lack of response to acetone confirmed the selectivity of the Ni/poly(EDOT-co-TAA) stacks for detecting toluene. It is anticipated that the assembly of other metals such as Ag, Au and Cu on top of poly(EDOT-co-TAA) would provide selectivity for detecting and discriminating other VOCs.

2010-03-26

300

All-Polymer Electrolytic Tilt Sensor with Conductive Poly(dimethylsiloxane) Electrodes  

Science.gov (United States)

In this study, an all-polymer electrolytic tilt sensor with conductive and corrosion-resistant poly(dimethylsiloxane) (PDMS) electrodes was designed and its performances were characterized. A PDMS cavity in the sensor for holding an electrolyte was fabricated by soft lithography using an ultraviolet-sensitive polymer. A conductive PDMS composite (gPDMS) with graphite powder was used for the electrode to measure the inclination angle of the electrolyte. A gPDMS composite with a graphite concentration above 40 wt % was able to function as a conductive polymer. The fabricated all-polymer tilt sensor exhibited a detectable inclination range of ± 60° and showed a relatively linear output signal compared with those exhibited by conventional micromachined tilt sensors with axis asymmetrical cavities. The maximum hysteresis of the output signal was approximately 0.1 V\\text{rms when the sensor repeatedly tilted and leveled off. In addition to the fundamental characterization of the sensor, various characteristics of the all-polymer tilt sensor, such as time-dependent and electrolyte-volume-dependent variations in the output signal, were investigated in this study. While the performance of the proposed sensor was comparable to that of conventional silicon-micromachined tilt sensors, the sensor could be produced at a fraction of the cost required to fabricate the conventional sensors.

Lee, June Kyoo; Choi, Ju Chan; Kong, Seong Ho

2013-06-01

 
 
 
 
301

Effects of dopants on the biomechanical properties of conducting polymer films on platinum electrodes.  

UK PubMed Central (United Kingdom)

Conducting polymers have often been described in literature as a coating for metal electrodes which will dampen the mechanical mismatch with neural tissue, encouraging intimate cell interactions. However there is very limited quantitative analysis of conducting polymer mechanics and the relation to tissue interactions. This paper systematically analyses the impact of coating platinum (Pt) electrodes with the conducting polymer poly(ethylene dioxythiophene) (PEDOT) doped with a series of common anions which have been explored for neural interfacing applications. Nanoindentation was used to determine the coating modulus and it was found that the polymer stiffness increased as the size of the dopant ion was increased, with PEDOT doped with polystyrene sulfonate (PSS) having the highest modulus at 3.2 GPa. This was more than double that of the ClO4 doped PEDOT at 1.3 GPa. Similarly, the electrical properties of these materials were shown to have a size dependent behaviour with the smaller anions producing PEDOT films with the highest charge transfer capacity and lowest impedance. Coating stiffness was found to have a negligible effect on in-vitro neural cell survival and differentiation, but rather polymer surface morphology, dopant toxicity and mobility is found to have the greatest impact.

Baek S; Green RA; Poole-Warren LA

2013-09-01

302

Conductivity enhancement induced by casting of polymer electrolytes under a magnetic field  

International Nuclear Information System (INIS)

Highlights: ? Ordering of polymer electrolytes under applied magnetic field. ? Positive effect of nanosize ferromagnetic filler. ? Structure-ion conductivity interrelationship. - Abstract: We recently presented a procedure for orienting the polyethylene-oxide (PEO) helices in a direction perpendicular to the film plane by casting the polymer electrolytes (PE) under a magnetic field (MF). Here we study the influence of magnetic fields of different strengths and configurations on the structural properties and ionic conductivity of concentrated LiCF3SO3 (LiTf) and LiAsF6:P(EO) pristine and composite polymer electrolytes containing ?-Fe2O3 nanoparticles. Some data of LiI:P(EO) system are shown for comparison. We suggest that the effect of type of salt (LiI, LiTf and LiAsF6) on the structure–conductivity relationship of the polymer electrolytes cast under magnetic field is closely connected to the crystallinity of the PEO–LiX system. It was found that the higher the content of the crystalline phase and the size of spherulites in the typically cast salt-polymer system, the stronger the influence of the magnetic field on the conductivity enhancement when the electrolyte is cast and dried under MF. Casting of the PE from a high-dielectric-constant solvent results in disentanglement of the PEO chains, which facilitates even more the perpendicular orientation of helices under applied MF. The enhancement of ionic conductivity was appreciably higher in the PEs cast under strong NdFeB magnets than under SmCo. Both bulk (intrachain) and grain-boundary conductivities increase when a MF is applied, but the improvement in the grain-boundary conductivity – associated with ion-hopping between polymer chains – is more pronounced. For LiAsF6:(PEO)3 at 65 °C, the interchain conductivity increased by a factor of 75, while the intrachain conductivity increased by a factor of 11–14. At room temperature, the SEI resistance of these PEs, cast under NdFeB HMF, decreased by a factor of up to 7, as compared to the typically cast polymer electrolytes. The effect of MF on orientation is observed directly down to the molecular level by 7Li nuclear magnetic resonance measurements.

2011-12-15

303

Ac conduction in conducting poly pyrrole-poly vinyl methyl ether polymer composite materials  

Energy Technology Data Exchange (ETDEWEB)

Composite materials containing conducting polypyrrole and insulating poly (vinyl methyl ether) (PVME) have been synthesized by oxidative polymerization of pyrrole in ethanol using FeCl{sub 3} oxidant in the presence of PVME. The ac conductivity measurements have been carried out in the frequency range of 100 Hz to 10 MHz and in the temperature range of 110 to 350 K. The frequency dependent conductivity has been explained on the basis of a small polaron tunnelling mechanism. {copyright} {ital 1997 American Institute of Physics.}

Saha, S.K. [Department of Physics, Durgapur Government College, Durgapur: 713214, West Bengal (India); Mandal, T.K.; Mandal, B.M. [Indian Association for the Cultivation of Science, Jadavpur, Calcutta: 700032 (India); Chakravorty, D. [Indian Association for the Cultivation of Science, Jadavpur, Calcutta: 700032 (India)]|[Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore (India)

1997-03-01

304

Developments in the Field of Conducting and Non-conducting Polymer Based Potentiometric Membrane Sensors for Ions Over the Past Decade  

Directory of Open Access Journals (Sweden)

Full Text Available Many research studies have been conducted on the use of conjugated polymers in the construction of chemical sensors including potentiometric, conductometric and amperometric sensors or biosensors over the last decade. The induction of conductivity on conjugated polymers by treating them with suitable oxidizing agents won Heeger, MacDiarmid and Shirakawa the 2000 Nobel Prize in Chemistry. Common conjugated polymers are poly(acetylene)s, poly(pyrrole)s, poly(thiophene)s, poly(terthiophene)s, poly(aniline)s, poly(fluorine)s, poly(3-alkylthiophene)s, polytetrathiafulvalenes, polynapthalenes, poly(p-phenylene sulfide), poly(p-phenylenevinylene)s, poly(3,4-ethylenedioxythiophene), polyparaphenylene, polyazulene, polyparaphenylene sulfide, polycarbazole and polydiaminonaphthalene. More than 60 sensors for inorganic cations and anions with different characteristics based on conducting polymers have been reported. There have also been reports on the application of non-conducting polymers (nCPs), i.e. PVC, in the construction of potentiometric membrane sensors for determination of more than 60 inorganic cations and anions. However, the leakage of ionophores from the membranes based on these polymers leads to relatively lower life times. In this article, we try to give an overview of Solid-Contact ISE (SCISE), Single-Piece ISE (SPISE), Conducting Polymer (CP)-Based, and also non-conducting polymer PVC-based ISEs for various ions which their difference is in the way of the polymer used with selective membrane. In SCISEs and SPISEs, the plasticized PVC containing the ionophore and ionic additives govern the selectivity behavior of the electrode and the conducting polymer is responsible of ion-to-electron transducer. However, in CPISEs, the conducting polymer layer is doped with a suitable ionophore which enhances the ion selectivity of the CP while its redox response has to be suppressed.

Farnoush Faridbod; Parviz Norouzi; Rassoul Dinarvand; Mohammad Reza Ganjali

2008-01-01

305

Ionic conductivity of the hyperbranched polymer-lithium metal salt systems  

Energy Technology Data Exchange (ETDEWEB)

Terminal-acetylated hyperbranched poly(ethylene glycol) derivatives containing diethylene and triethylene glycols and 3,5-dioxybenzoate branching units were prepared and the ionic conductivities of these polymers complexed with lithium metal salts such as LiCF{sub 3}SO{sub 3} and Li(CF{sub 3}SO{sub 2}){sub 2}N as polymer electrolytes were investigated. It was found that the hyperbranched polymer with a triethylene glycol chain and with Li(CF{sub 3}SO{sub 2}){sub 2}N shows higher conductivity and also the number of charge carriers increases with Li(CF{sub 3}SO{sub 2}){sub 2}N salt concentration. (orig.)

Itoh, Takahito; Ikeda, Motoka; Hirata, Nobuyuki; Moriya, Yuji; Kubo, Masataka; Yamamoto, Osamu [Mie Univ., Tsu (Japan). Dept. of Chemistry

1999-09-01

306

Sulfonation and characterization of styrene-indene copolymers for the development of proton conducting polymer membranes  

Directory of Open Access Journals (Sweden)

Full Text Available The aim of this work is to obtain polymer precursors based on styrene copolymers with distinct degrees of sulfonation, as an alternative material for fuel cell membranes. Acetyl sulfate was used to carry out the sulfonation and the performance of the polyelectrolyte was evaluated based on the content of acid polar groups incorporated into the macromolecular chain. Polymeric films were produced by blending the sulfonated styrene-indene copolymer with poly(vinylidene fluoride). The degree of sulfonation of the polymer was strongly affected by the sulfonation reaction parameters, with a direct impact on the ionic exchange capacity and the ionic conductivity of the sulfonated polymers and the membranes obtained from them. The films produced with the blends showed more suitable mechanical properties, although the conductivity of the membranes was still lower than that of commercially available membranes used in fuel cells.

Cristiane M. Becker; Amanda B. Biagini; Maria M. C. Forte; Sandro C. Amico; José V. C. Vargas; Denise S. Azambuja

2012-01-01

307

Nuclear magnetic resonance and conductivity study of starch based polymer electrolytes  

International Nuclear Information System (INIS)

Nuclear magnetic resonance (NMR) spectroscopy and complex impedance spectroscopy have been used to study the polymer electrolytes formed by amylopectin rich starch, plasticized with glycerol and containing lithium perchlorate. The 7Li and 1H NMR linewidth narrowing occurs close to the glass transition temperature (Tg) of the plasticized electrolytes. The heteronuclear decoupling NMR experiments suggest a weaker Li-polymer interaction in the plasticized electrolyte when compared with the unplasticized ones. The effects of the plasticizer on the ionic mobility in these starch-based electrolytes, as measured by NMR spin-lattice relaxation and conductivity, are discussed. The 7Li NMR relaxation results indicate that the ionic mobility in these plasticized electrolytes seems to be controlled by the plasticizer molecules. The dynamical parameters obtained from the conductivity and NMR data demonstrate that the Li+ mobility in our systems is comparable to those found in others plasticized polymer electrolytes.

2003-06-30

308

Electric Field Induced Hopping Conductivity: An Investigation of Electric Field-Dependent Resistivity in Polymers  

Science.gov (United States)

The resistivity of highly insulating materials exhibits a dependence on electric field strength. Mott and Davis as well as Poole and Frankle describe theoretically the resistivity of disordered semiconductors, when subject to a changing electric field, in terms of hopping conductivity models. While these models have often been applied to polymers, there is little direct experimental evidence to confirm the validity of the theories for polymers. We present such results for a newly-developed block co-polymer Hytrel, a highly insulating material similar to Teflon. The constant voltage resistivity test method has been used to study Hytrel for a range of electric fields up to electrostatic breakdown. We consider whether the Hytrel results are consistent with existing models of electric-field induced hopping conductivity.

Hart, S. R.; Brunson, J.; Dennison, J. R.

2006-10-01

309

Ion conduction mechanism in non-aqueous polymer electrolytes based on oxalic acid: Effect of plasticizer and polymer  

Energy Technology Data Exchange (ETDEWEB)

Non-aqueous proton-conducting polymer electrolytes in the film form are synthesized through the complexation of oxalic acid (OA) and polyvinylidenefluoride-co-hexafluoro propylene (PVdF-HFP). Interestingly, the addition of a small amount of the basic component dimethylacetamide (DMA) gives rise to a three-order increase in conductivity. The value is found to depend on the concentrations of the weak acid and DMA in the electrolytes. A maximum conductivity of 0.12x10{sup -3}Scm{sup -1} has been achieved at ambient temperature for electrolytes containing 40wt.% OA with DMA. The observed increase in conductivity is considered to be due to interactions taking place between the high dielectric polymer media, the acid and the basic plasticizer. These interactions are confirmed from fourier transform infra red (FTIR) studies and supported by differential scanning calorimetry (DSC) measurements. Apart from providing acid-base interaction, the base DMA also improves the surface morphology and reduces the pore volume, both of which help to retain the acid-base complex within the membrane. (author)

Missan, Harinder Pal Singh; Chu, P.P. [Department of Chemistry, National Central University, Chungli 32001 (Taiwan); Sekhon, S.S. [Department of Applied Physics, Guru Nanak Dev University, Amritsar, Punjab 143005 (India)

2006-08-25

310

Photomodulation spectroscopy of photocarrier dynamics, electronic defects and morphology of conducting polymers  

International Nuclear Information System (INIS)

[en] A variety of techniques were used: CW photomodulation, photomodulation in femtosecond and picosecond time ranges, CW resonant Raman scattering, transient photoinduced Raman scattering, electro-absorption, degenerate four-wave mixing, spin dependent photomodulation, and absorption detected magnetic resonance. The following conducting polymers were studied: polyacetylene, polythiophene, polydiacetylene 4-BCMU, polydiethynylsilanes, polysilane embedded in a-Si:H matrix, and fullerenes

1993-01-01

311

Ionic conductivity and transport number of lithium ion in polymer electrolytes containing PEG-borate ester  

International Nuclear Information System (INIS)

We investigated the effects of PEG-borate ester on the ionic conductivity and transport number of lithium ions in polymer electrolytes with Li-salt, such as LiN(CF3SO2)2, LiClO4 or LiCF3SO3. The ionic conductivity of the polymer electrolyte with LiN(CF3SO2)2 was found to be higher than those of the electrolytes with LiClO4 or LiCF3SO3. This result is mainly concerned with mobility of ions, which is indicated by the comparison of glass transition temperatures of the polymer electrolytes. On the other hand, the transport numbers of lithium ions in the polymer electrolytes with LiClO4 or LiCF3SO3 were higher than those of the electrolyte with LiN(CF3SO3)2. Furthermore, the conductivities of lithium ions calculated by multiplying the ionic conductivity measured by ac impedance with transport number of lithium ions were also found to be higher than that of the electrolytes with LiN(CF3SO2). These results indicate that the PEG-borate ester acts as Lewis acid and interacts with CF3SO3- or ClO4- more effectively compared with N(CF3SO2)2-, leading to improved dissociation of Li-salts and transport number of lithium ions.

2004-11-30

312

A facile avenue to conductive polymer brushes via cyclopentadiene-maleimide Diels-Alder ligation.  

UK PubMed Central (United Kingdom)

Cyclopentadienyl end-capped poly(3-hexylthiophene) was employed to fabricate conductive surface tethered polymer brushes via a facile route based on cyclopentadiene-maleimide Diels-Alder ligation. The efficient nature of the Diels-Alder ligation was further combined with a biomimetic polydopamine-assisted functionalization of surfaces, making it an access route of choice for P3HT surface immobilization.

Yameen B; Rodriguez-Emmenegger C; Preuss CM; Pop-Georgievski O; Verveniotis E; Trouillet V; Rezek B; Barner-Kowollik C

2013-08-01

313

Meniscus confined fabrication of multidimensional conducting polymer nanostructures with scanning electrochemical cell microscopy (SECCM).  

UK PubMed Central (United Kingdom)

Scanning electrochemical cell microscopy (SECCM) is demonstrated as a new approach for the construction of extended multi-dimensional conducting polymer (polyaniline) nanostructures, making use of a mobile dual-channel theta pipette cell to control and monitor the location, rate and extent of electropolymerisation.

McKelvey K; O'Connell MA; Unwin PR

2013-04-01

314

Preparation and physical properties of highly conducting metal (M = Ni, Co, Cu) coordination polymers  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Coordination polymers of nickel, cobalt and copper with the linking polydentate ligands tetrathiafulvalenetetrathiolate, benzene-1,2,4,5-tetrathiolate and phthalocyaninate have been prepared. The environmentally very stable materials have dc conductivities ranging between 10-2 S·cm-1 for the polypht...

Dahm, Stefan; Strunz, Werner; Keller, Heimo J.; Schweitzer, Dieter

315

Research progress on a novel conductive polymer-poly(3,4-ethylenedioxythiophene) (PEDOT)  

Energy Technology Data Exchange (ETDEWEB)

In this paper the progress in study on a new organic conducting polymer-poly(3,4-ethylenedioxythiophene) (PEDOT) is reviewed. Its ground-state structure, excellent advantages and morphology are presented. Then the modification ways such as its copolymers and composites are introduced in detail. Moreover, the applications of PEDOT are also summarized.

Wang, Y [Department of Polymer Materials and Engineering, College of Materials Science and Engineering, Shandong University of Science and Technology, 579 Qianwangang Road, Qingdao Economic and Technical Development Zone, Qingdao, Shandong Province, 266510 (China)], E-mail: holylilyee@163.com

2009-03-01

316

Research progress on a novel conductive polymer-poly(3,4-ethylenedioxythiophene) (PEDOT)  

International Nuclear Information System (INIS)

[en] In this paper the progress in study on a new organic conducting polymer-poly(3,4-ethylenedioxythiophene) (PEDOT) is reviewed. Its ground-state structure, excellent advantages and morphology are presented. Then the modification ways such as its copolymers and composites are introduced in detail. Moreover, the applications of PEDOT are also summarized.

2009-03-01

317

Electroactive Surfaces Based on Conducting Polymers for Controlling Cell Adhesion, Signaling, and Proliferation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We report on a variety of electroactive surfaces for the control of in vitro cell adhesion, proliferation, and stimulation. Planar cell culture substrates have been coated with the conducting polymer PEDOT and by switching the redox state, adhesion and proliferation of MDCK epithelial cells was cont...

Jager, Edwin; Bolin, Maria; Svennersten, Karl; Wang, X; Richter-Dahlfors, Agneta; Berggren, Magnus

318

Electrochemically-deposited benzophenone moieties: precursors for dual mode patterning of polymer brushes on conducting surfaces.  

Science.gov (United States)

A new method for patterning polymer brushes on conducting surfaces via electro-deposited benzophenone moieties is reported. The dual patterning capability of the technique was demonstrated and characterized via the AFM and for the first time, an IR-imaging technique for a patterned brush. PMID:21127779

Tria, Maria Celeste; Park, Jin Young; Advincula, Rigoberto

2010-12-02

319

Electrochemically-deposited benzophenone moieties: precursors for dual mode patterning of polymer brushes on conducting surfaces.  

UK PubMed Central (United Kingdom)

A new method for patterning polymer brushes on conducting surfaces via electro-deposited benzophenone moieties is reported. The dual patterning capability of the technique was demonstrated and characterized via the AFM and for the first time, an IR-imaging technique for a patterned brush.

Tria MC; Park JY; Advincula R

2011-02-01

320

Photomodulation spectroscopy of photocarrier dynamics, electronic defects and morphology of conducting polymers  

Energy Technology Data Exchange (ETDEWEB)

A variety of techniques were used: CW photomodulation, photomodulation in femtosecond and picosecond time ranges, CW resonant Raman scattering, transient photoinduced Raman scattering, electro-absorption, degenerate four-wave mixing, spin dependent photomodulation, and absorption detected magnetic resonance. The following conducting polymers were studied: polyacetylene, polythiophene, polydiacetylene 4-BCMU, polydiethynylsilanes, polysilane embedded in a-Si:H matrix, and fullerenes.

Vardeny, Z.V.

1993-01-01

 
 
 
 
321

Conductivities and transport properties of microporous molecular sieves doped composite polymer electrolyte used for lithium polymer battery  

Energy Technology Data Exchange (ETDEWEB)

Microporous molecular sieves (MMS), due to their potential for advanced applications in separation technologies, catalysis, and nano-science, have attracted much attention in the past decades. In this work, a novel PEO-based all solid-state composite polymer electrolyte by using MMS as filler is developed. Thermal analysis and polarized optical microscopy results show that MMS can increase the amount of PEO spherulites and decrease their size, which is beneficial for decreasing the crystallinity of PEO. There exists a much more continuous amorphous phase of PEO in PEO-LiClO{sub 4}/MMS compared with the continuous crystalline phase of PEO in pristine PEO-LiClO{sub 4}, which results in enhancement of ionic conductivity. The excellent lithium transporting properties combined with high decomposition voltage ensures the use of PEO-LiClO{sub 4}/MMS as a candidate electrolyte material for all solid-state re-chargeable lithium polymer batteries. (authors)

Jingyu, Xi; Yuxia, Bai; Xinping, Qiu; Wenta, Zhu; Liquan, Chen [Tsinghua Univ., Key Lab. of Organic Optoelectronics and Molecular Engineering, Dept. of Chemistry, Beijing, BJ (China); Xiaozhen, Tang [Shanghai Jiao Tong Univ., School of Chemistry and Chemical Technology (China)

2005-11-15

322

Colloidally templated two-dimensional conducting polymer arrays and SAMs: binary composition patterning and chemistry.  

Science.gov (United States)

A facile approach and strategy toward binary-composition, two-dimensional (2D) patterned surfaces of conducting polymer periodic arrays, together with thiol self-assembled monolayers (SAMs) is described. The method involved a Langmuir-Blodgett (LB)-like deposition of latex microsphere particles, electropolymerization via cyclic voltammetric (CV) techniques, and self-assembly of an amphiphile. The LB-like technique enabled the monolayer deposition of different sizes of polystyrene (PS) particles in hexagonal packing arrangement on planar substrates. Combining the LB-like method with CV electropolymerization is advantageous because it provides deposition control of a polymer interconnected network, controlled composition ratio of polymer and SAMs, and control of 2D size and spacing of the spherical void pattern. Electrochemical-quartz crystal microbalance (EC-QCM) in situ monitoring of the film deposition quantified a constant and linear growth rate, with varying viscoelastic behavior of the conducting polymer adsorption on planar and PS-templated substrates. The dual-patterned surface provided a good imaging contrast as observed by atomic force microscopy (AFM). Complementary analyses such as X-ray photoelectron spectroscopy (XPS), attenuated total internal reflection infrared (ATR IR) spectroscopy, ultraviolet-visible (UV-vis) spectroscopy, and static contact angle measurements were used to characterize the formation of the patterned surface. The versatility of the method enables the potential for making various types of quantitative binary compositions and patterned surfaces using different combinations of conducting polymer or functional SAMs, which can be extended in the future to polymer brushes and layer-by-layer assembly of various materials. PMID:21355551

Pernites, Roderick B; Felipe, Mary Jane L; Foster, Edward L; Advincula, Rigoberto C

2011-02-28

323

Colloidally templated two-dimensional conducting polymer arrays and SAMs: binary composition patterning and chemistry.  

UK PubMed Central (United Kingdom)

A facile approach and strategy toward binary-composition, two-dimensional (2D) patterned surfaces of conducting polymer periodic arrays, together with thiol self-assembled monolayers (SAMs) is described. The method involved a Langmuir-Blodgett (LB)-like deposition of latex microsphere particles, electropolymerization via cyclic voltammetric (CV) techniques, and self-assembly of an amphiphile. The LB-like technique enabled the monolayer deposition of different sizes of polystyrene (PS) particles in hexagonal packing arrangement on planar substrates. Combining the LB-like method with CV electropolymerization is advantageous because it provides deposition control of a polymer interconnected network, controlled composition ratio of polymer and SAMs, and control of 2D size and spacing of the spherical void pattern. Electrochemical-quartz crystal microbalance (EC-QCM) in situ monitoring of the film deposition quantified a constant and linear growth rate, with varying viscoelastic behavior of the conducting polymer adsorption on planar and PS-templated substrates. The dual-patterned surface provided a good imaging contrast as observed by atomic force microscopy (AFM). Complementary analyses such as X-ray photoelectron spectroscopy (XPS), attenuated total internal reflection infrared (ATR IR) spectroscopy, ultraviolet-visible (UV-vis) spectroscopy, and static contact angle measurements were used to characterize the formation of the patterned surface. The versatility of the method enables the potential for making various types of quantitative binary compositions and patterned surfaces using different combinations of conducting polymer or functional SAMs, which can be extended in the future to polymer brushes and layer-by-layer assembly of various materials.

Pernites RB; Felipe MJ; Foster EL; Advincula RC

2011-03-01

324

Effect of the silica precursor on the conductivity of hectorite-derived polymer nanocomposites  

International Nuclear Information System (INIS)

New hectorite and organo-hectorite clays have been prepared using different silica sol sources, in order to examine the importance of sol particle size, pH, and surface chemistry on the final matrix. Polymer-clay nanocomposites (PCN) are prepared by intercalating polyethylene oxide in the clay layers of lithium hectorites. The resulting films are physically and electrochemically evaluated. Conductivity values, activation energies, and lithium transference numbers indicate that the PCNs are single ion conductors with transference numbers close to unity. The activation energies are in the range of 0.02 V, two orders of magnitude lower than the conventional polymer electrolytes.

2005-06-30

325

Calculation of the band structure of 2d conducting polymers using the network model  

International Nuclear Information System (INIS)

the network model has been used to calculate the band structure the gap energy and Fermi level of conducting polymers in two dimensions. For this purpose, a geometrical classification of possible polymer chains configurations in two dimensions has been introduced leading to a classification of the unit cells based on the number of bonds in them. The model has been applied to graphite in 2D, represented by a three bonds unit cell, and, as a new case, the anti-parallel Polyacetylene chains (PA) in two dimensions, represented by a unit cell with four bons. The results are in good agreement with the first principles calculations. (author)

2007-01-01

326

New fabrication technique of conductive polymer/insulating polymer composite films and evaluation of biocompatibility in neuron cultures  

International Nuclear Information System (INIS)

Poly(vinyl alcohol), PVA, produces a flexible composite polymer film with electrical, optical and electrochemical properties very similar to those of polypyrrole (PPy). The rate of electrochemical polymerization depends on the diffusion rate of the electrolyte across the PVA film to the indium tin oxide (ITO) electrode. In particular, a solvent with a hydrophilic nature easily penetrates into the PVA film. By applying this new process, we demonstrate a unique method of forming an electrically conductive pattern in PVA film. It will be possible to develop electrodes for electrical stimulation of the nervous system using the conducting polymer, PPy. Then, by applying a similar technique, we fabricated poly(3,4-ethylenedioxythiophene), PEDOT/PVA, composite films and investigated their basic electrochemical properties. Moreover, in this study, in order to develop a novel cell-culture system which makes it possible to communicate with cultured cells, fibroblasts were cultured on PPy- and PEDOT-coated ITO conductive glass plates for 7 days. The result reveals that the PPy and PEDOT films support the secretory functions of the cells cultured on its surface. The PPy- and PEDOT-coated electrodes may be useful to culture the cells on.

2009-11-30

327

Study on power generation using electro-conductive polymer and its mixture with magnetic fluid  

Energy Technology Data Exchange (ETDEWEB)

A new power generation system using electro-conductive polymer and its mixture with magnetic fluid is introduced. The system using non-poison electro-conductive polymer and its mixture with magnetic fluid and operating at room temperature is proposed in the present paper. The system could be used as a micro-distributed energy supply system for domestic use in the future. An experimental set-up is designed and established to investigate the performance of the power generation with an aid of a theoretical analysis of the power generation. It is found that the theoretical results are in good agreement with the measured data. Based on the obtained results, the electric output increases with Reynolds number, size of the test channel, magnetic strength and electric conductivity. It is understood that in order to obtain a practical power generation, priority should be put on increasing fluid flow velocity and magnetic field strength.

Yamaguchi, Hiroshi [Department of Mechanical Engineering, Doshisha University, Kyo-Tanabeshi, Kyoto 610-0321 (Japan); Zhang Xinrong [Department of Energy and Resources Engineering, College of Engineering, Peking University, Beijing, 100871 (China); Department of Mechanical Engineering, Doshisha University, Kyo-Tanabeshi, Kyoto 610-0321 (Japan)], E-mail: xrzhang@coe.pku.edu.cn; Higashi, Shidei; Li, Mingjun [Department of Mechanical Engineering, Doshisha University, Kyo-Tanabeshi, Kyoto 610-0321 (Japan)

2008-04-15

328

One-step inkjet printing of conductive silver tracks on polymer substrates  

International Nuclear Information System (INIS)

[en] A one-step process to fabricate conductive features on flexible polymer substrates by inkjet printing an organometallic silver ink directly onto a substrate that is heated to 130 deg. C is presented. This process led to the immediate sintering of the printed features. The samples were left for 5 min at elevated temperature, which resulted in conductive silver features with a resistivity of eight times the bulk silver value. The combination of this ink and the simultaneous printing/sintering process opens up routes for the direct fabrication of conductive features on common polymer substrates that could be applied, for example, in roll-to-roll production of flexible microelectronic systems.

2009-04-22

329

Ionic Conductivity Trends with Molecular Weight in PEO and PEO-Based Solid Polymer Electrolytes  

Science.gov (United States)

Poly(ethylene oxide) based polymer electrolytes with lithium bis(trifluoromethane)sulfonamide (LiTFSI) salt remain one of the most promising class of solid polymer electrolyte for rechargeable lithium metal batteries. Among those, poly(styrene-b-ethyleneoxide) (SEO) doped with LiTFSI has been shown to exhibit acceptable levels of conductivity while possessing a sufficiently high modulus to suppress the growth of dendrites. The purpose of this study is to explore the molecular weight dependence on conductivity for the PEO/LiTFSI system to which previous studies have alluded, but never quantified, and contrast this with the observed molecular weight dependence of SEO reported in previous work. Conductivities were measured using AC impedance spectroscopy over a broad range of temperatures and molecular weights beyond those reported in the literature.

Teran, Alexander; Mullin, Scott; Wanakule, Nisita; Panday, Ashoutosh; Balsara, Nitash

2010-03-01

330

On the dissipative effects in the electron transport through conducting polymer nanofibers  

CERN Multimedia

Here, we study the effects of stochastic nuclear motions on the electron transport in doped polymer fibers assuming the conducting state of the material. We treat conducting polymers as granular metals and apply the quantum theory of conduction in mesoscopic systems to describe the electron transport between the metalliclike granules. To analyze the effects of nuclear motions we mimic them by the phonon bath, and we include the electron-phonon interactions in consideration. Our results show that the phonon bath plays a crucial part in the intergrain electron transport at moderately low and room temperatures suppressing the original intermediate state for the resonance electron tunneling, and producing new states which support the electron transport.

Zimbovskaya, N A

2006-01-01

331

Polymer single crystal-decorated superhydrophobic buckypaper with controlled wetting and conductivity.  

Science.gov (United States)

Herein we report fabrication of uniform, free-standing nanohybrid buckypaper with high carbon nanotube (CNT) contents (13-70%) using polymer single crystal-decorated CNTs as the precursor. Polyethylene single crystals were periodically grown on CNT surfaces, forming a nanohybrid shish kebab (NHSK) structure. Vacuum filtering a NHSK suspension led to polymer single crystal-decorated buckypaper (named as NHSK paper) with a wide range of CNT contents and uniform CNT dispersion. Porosity, surface roughness, and conductivity of NHSK paper can be controlled by tuning the polymer single crystal size. Because of the hierarchical roughness created by intra- and inter-NHSK nanostructure, NHSK paper with controlled kebab size exhibits both superhydrophobicity and high surface water adhesion, which mimics the rose petal effect. We anticipate that this unique NHSK paper can find applications in sensors, electrochemical devices, and coatings. PMID:22243213

Laird, Eric D; Wang, Wenda; Cheng, Shan; Li, Bing; Presser, Volker; Dyatkin, Boris; Gogotsi, Yury; Li, Christopher Y

2012-01-20

332

Polymer single crystal-decorated superhydrophobic buckypaper with controlled wetting and conductivity.  

UK PubMed Central (United Kingdom)

Herein we report fabrication of uniform, free-standing nanohybrid buckypaper with high carbon nanotube (CNT) contents (13-70%) using polymer single crystal-decorated CNTs as the precursor. Polyethylene single crystals were periodically grown on CNT surfaces, forming a nanohybrid shish kebab (NHSK) structure. Vacuum filtering a NHSK suspension led to polymer single crystal-decorated buckypaper (named as NHSK paper) with a wide range of CNT contents and uniform CNT dispersion. Porosity, surface roughness, and conductivity of NHSK paper can be controlled by tuning the polymer single crystal size. Because of the hierarchical roughness created by intra- and inter-NHSK nanostructure, NHSK paper with controlled kebab size exhibits both superhydrophobicity and high surface water adhesion, which mimics the rose petal effect. We anticipate that this unique NHSK paper can find applications in sensors, electrochemical devices, and coatings.

Laird ED; Wang W; Cheng S; Li B; Presser V; Dyatkin B; Gogotsi Y; Li CY

2012-02-01

333

Ionic conductivities of solid polymer electrolyte/salt systems: Group-contribution method  

Energy Technology Data Exchange (ETDEWEB)

We establish a new group-contribution model based on the Nernst-Einstein equation in which the diffusion coefficient is derived from the modified double-lattice (MDL) model and the Debye-Huckel (DH) theory. The model includes the combinatorial energy contribution that is responsible for the revised Flory-Huggins entropy of mixing, the van der Waals energy contribution from dispersion, and the polar force and the specific energy contribution from hydrogen bonding. The Nernst-Einstein equation takes into account the mobility of the salt and the motion of the polymer host. To describe the segmental motion of the polymer chain, which is the well known conduction mechanism for solid polymer electrolyte (SPE) systems, the effective co-ordinated unit parameter is introduced. Our results show that good agreement is obtained upon comparison with experimental data of various PEO and salt systems in the interested ranges. (author)

Joo, Jae Ho; Bae, Young Chan [Division of Chemical Engineering and Molecular Thermodynamics Laboratory, Hanyang University, Seoul 133791 (Korea, Republic of)

2006-06-19

334

Ionic conductivity enhancement in Na2SO4-PAN polymer composites  

International Nuclear Information System (INIS)

The ionic conductivity of sodium sulfate Na2SO4-polyacrylonitrile (PAN) composites has been measured for various compositions. The ionic conductivity has been found to be enhanced up to six times with the addition of PAN polymer. The enhancement of conductivity with composite formation is strange because PAN itself is simply a matrix material. The phase transitions of Na2SO4 are observed to be dependent on the existence of PAN, only in the first heating run of Na2SO4(V). These are discussed with the peculiarities of the structural phase transitions in Na2SO4. With the addition of PAN, the mechanical properties are greatly improved.

2005-05-25

335

Nonequilibrium molecular dynamics methods for computing the thermal conductivity: application to amorphous polymers.  

UK PubMed Central (United Kingdom)

We develop two nonequilibrium simulation methods which are suitable for calculation of thermal conductivity with good accuracy. These methods are based on simple algorithms, and it will be very easy to extend their range of application. In particular, there are no restrictions (from, e.g., the force field) to apply them to a variety of systems. Here, they are applied to the calculation of the thermal conductivity of amorphous polyamide-6,6 systems. We treat two models of the polymer with different degrees of freedoms constrained. The results suggest that the methods are quite efficient, and that thermal conductivity strongly depends on the number of degrees of freedom in the model.

Terao T; Lussetti E; Müller-Plathe F

2007-05-01

336

Evaluation of interactive effects on the ionic conduction properties of polymer gel electrolytes.  

UK PubMed Central (United Kingdom)

Ionic mobility of electrolyte materials is essentially determined by the nanoscale interactions, the ion-ion interactions and ion-solvent interactions. We quantitatively evaluated the interactive situation of the lithium polymer gel electrolytes through the measurements of ionic conductivity and diffusion coefficients of the mobile species of the lithium polymer electrolytes. The interactive force between the cation and anion in the gel depended on the mixing ratio of the binary solvent, ethylene carbonate plus dimethyl carbonate (EC/DMC). The gel with the solvent (3:7 EC:DMC) showed minimal cation-anion interaction, which is the cause of the highest ionic mobility compared with those of the other gels with different solvents. This suggests that the cation-anion interaction does not simply depend on the dielectric constant of the solvent but is associated with the solvation condition of the lithium. In the case of the gel with the 3:7 EC/DMC solvent, most of the EC species strongly coordinate to a lithium ion, forming the stable solvated lithium, Li(EC)(3)(+), and there are no residual EC species for exchange with them. As a result, the solvating EC species would be a barrier that restricts the anion attack to the lithium leading to the smallest cation-anion interaction. On the other hand, interaction between the cation and polar sites, hydroxyl and oxygen groups of ether of the polyvinyl butyral (PVB) and polyethylene oxide (PEO) polymer, respectively, in the gels was another dominant factor responsible for cation mobility. It increased with increasing polar site concentration per lithium. In case of the PVB gels, cation-anion interaction increased with an increasing polymer fraction of the gel contrary to the independent feature of PEO gels with the change of the polymer fraction. This indicates that the cation-anion interaction is associated with the polymer structure of the gel characterized by the kind and configuration of polar groups, molecular weight, and network morphology of the polymer.

Saito Y; Okano M; Kubota K; Sakai T; Fujioka J; Kawakami T

2012-08-01

337

Modification of Conductive Polymer for Polymeric Anodes of Flexible Organic Light-Emitting Diodes  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract A conductive polymer, poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), was modified with dimethyl sulfoxide (DMSO) in solution state, together with sub-sequential thermal treatment of its spin-coated film. The electrical conductivity increased by more than three orders of magnitude improvement was achieved. The mechanism for the conductivity improvement was studied at nanoscale by particle size analysis, field emission scanning electron microscopy (FESEM), and X-ray photoelectron spectroscopy (XPS). Smaller particle size was observed, resulting in larger contact area and better electrical conductive connections. Connection of conductive PEDOT increased on the surface of the PEDOT:PSS particles, which promoted high conductivity. Flexible anodes based on the modified PEDOT:PSS were fabricated. Flexible organic light-emitting diodes (FOLED) based the polymeric anodes have a comparable performance to those on indium–tin–oxide (ITO) anodes.

Wang Guang-Feng; Tao Xiao-Ming; Xin John; Fei Bin

2009-01-01

338

Conductivity of microfibrillar polymer-polymer composites with CNT-loaded microfibrils or compatibilizer: A comparative study  

Directory of Open Access Journals (Sweden)

Full Text Available Conductive polymer composites have wide ranging applications, but when they are produced by conventional melt blending, high conductive filler loadings are normally required, hindering their processability and reducing mechanical properties. In this study, two types of polymer-polymer composites were studied: i) microfibrillar composites (MFC) of polypropylene (PP) and 5 wt% carbon nanotube (CNT) loaded poly(butylene terephthalate) (PBT) as reinforcement, and ii) maleic anhydride-grafted polypropylene (PP-g-MA) compatibilizer, loaded with 5 wt% CNTs introduced into an MFC of PP and poly(ethylene terephthalate) (PET) in concentrations of 5 and 10 wt%. For the compatibilized composite type, PP and PET were melt-blended, cold-drawn and pelletized, followed by dry-mixing with PP-g-MA/CNT, re-extrusion at 200°C, and cold-drawing. The drawn blends produced were compression moulded to produce sheets with MFC structure. Using scanning electron microscopy, CNTs coated with PP-g-MA could be observed at the interface between PP matrix and PET microfibrils in the compatibilized blends. The volume resistivities tested by four-point test method were: 2.87•108 and 9.93•107 ?•cm for the 66.5/28.5/5 and 63/27/10 (by wt%) PP/PET/(PP-g-MA/CNT) blends, corresponding to total CNT loadings (in the composites) of 0.07 vol% (0.24 wt%) and 0.14 vol% (0.46 wt%), respectively. For the non-compatibilized MFC types based on PP/(PBT/CNT) with higher and lower melt flow grades of PP, the resistivities of 70/(95/5) blends were 1.9•106 and 1.5•107 ?•cm, respectively, corresponding to a total filler loading (in the composite) of 0.44 vol% (1.5 wt%) in both MFCs.

S. Fakirov; S. M. Panamoottil; P. Potschke; R. J. T. Lin; D. Bhattacharyya

2013-01-01

339

TITANIUM DIOXIDE TRIADS FOR IMPROVED CHARGE-SEPARATION USING CONDUCTIVE POLYMERS  

Energy Technology Data Exchange (ETDEWEB)

Dye-sensitized solar cells are potentially one of the best solutions to solar energy conversion because of the low cost of required materials and production processes. Titanium dioxide (TiO2) nanoparticulate fi lms are the basis for one of these types of cells, providing large surface area for dye-sensitizer adsorption. Because TiO2 nanoparticulate fi lms develop defects caused by oxygen defi ciency, deep reactive electron traps are formed. With the addition of an enediol ligand, these electron traps are deliberately removed, enhancing the conduction of electrons within the fi lm. In this project, TiO2 nanoparticulate fi lms made by a layer-by-layer dip coating method were modifi ed with 3,4-dihydroxyphenylacetic acid (DOPAC). DOPAC binds to the titanium atoms on the surface of the nanoparticles, restoring their octahedral geometry. This restructuring of the surface shifts the spectral properties of the TiO2 to the visible spectrum and improves the separation of charges which is observed using photoelectrochemistry. Furthermore, DOPAC enables the electronic attachment of other molecules to the surface of TiO2 fi lms, such as the conductive polymer polyaniline base. This conductive polymer provides an extended separation of charges which increases photocurrent production by forming a triad with the TiO2 semiconductor through the 3,4-dihydroxyphenylacetic acid linker. The photocurrent increases due to the donor properties of the conductive polymer thereby decreasing charge pair recombination.

Cochran, T.M.; Gaylor, T.N.; de la Garza, L.; Rajh, T.

2009-01-01

340

Micropatterning of a stretchable conductive polymer using inkjet printing and agarose stamping  

DEFF Research Database (Denmark)

A highly conducting stretchable polymer material has been patterned using additive inkjet printing and by subtractive agarose stamping of a deactivation agent (hypochlorite). The material consisted of elastomeric polyurethane combined in an interpenetrating network with a conductive polymer, poly(3,4-ethylenedioxythiophene) (PEDOT). The agarose stamping produced 50 ?m wide conducting lines with high spatial fidelity. The deactivation agent was found to cause some degradation of the remaining conducting lines, as revealed by a stronger increase in resistance upon straining compared to the pristine polymer material. Inkjet printing of the material was only possible if a short-chain polyurethane was used as elastomer to overcome strain hardening at the neck of the droplets produced for printing. Reproducible line widths down to 200 ?m could be achieved by inkjet printing. Both methods were used to fabricate test patterns that allowed the electrical resistance parallel and perpendicular to the elongation direction to be measured. Electrical resistance increased both parallel and perpendicular to the direction of strain, with a faster increase observed parallel to the straining.

Hansen, Thomas Steen; Hassager, Ole

2007-01-01

 
 
 
 
341

Conducting polymer actuator based on chemically deposited polypyrrole and polyurethane-based solid polymer electrolyte working in air  

International Nuclear Information System (INIS)

[en] Conducting polymers (CPs), such as polypyrrole, polythiophene, and polyaniline, are unique in that they have switchable properties due to their two or more mechanically stable oxidation states. Thus, their films or coatings can be easily switched by the application of a small voltage and current to change their volume during electrochemical redox processes. In particular, polypyrrole (PPy) has been studied most extensively because of its high electrical conductivity and good environmental stability under ambient conditions. In this work, we have studied a new CP actuator, fully polymeric, assembled with two PPy film electrodes and a solid polymer electrolyte (SPE), polyurethane/Mg(ClO4)2. Polyurethanes (PUs) were synthesized from 4,4'-diphenylmethane diisocyanate (MDI), 1,4-butanediol (1,4-BD) and three types of polyol: poly(ethylene glycol) (PEG), poly(propylene glycol) (PPG), and PPG-block-PEG-block-PPG (PPG-co-PEG). The chemical polymerization of PPy by immersion in Py monomer aqueous solution and oxidant aqueous solution is an adequate method to prepare PU/PPy composite film as an actuator. To find the proper thickness of the PPy coating layer for actuation, we measured the displacements of the actuators according to the thickness of the PPy coating layer. The displacement of all actuators is discussed in connection with the properties of the SPE and PPy. All the results obtained in this work show the feasibility of electrochemomechanical devices based on PPy and SPE film being able to work in air

2009-01-01

342

An all-polymer micropump based on the conductive polymer poly(3,4-ethylenedioxythiophene) and a polyurethane channel system  

DEFF Research Database (Denmark)

An all-polymer micropunlp was realized using the conductive polymer poly(3,4-ethylenedioxythiophene) (PEDT) as the active cODlponent. The pUlnping effect originated fronl an ac potential applied to an aSylnlnetric array of interdigitat.ed electrodes. The PEDT electrodes were fabricated using optical lithography and reactive ion etching, and dimensions down to 2 jtD) could be successfully realize·d. The channel systeDl wasm.ade froln a flexible thennoplastic polyurethane. The chosen polyurethane exhibited good sealing without the possible contanlination issues of silicones, adequate wetting without plasma treatment, and has the potential for Dlass production, e.g., by injection lTIoulding. The assembled micropunlp showed a pUDlping speed of 150 /LID s-l at a frequency of 10 kHz and an alnplitude of 5 V. Higher potentials resulted in pennanent dalnage to the pUlnp electrodes. Encapsulation of t.he conducting polylner electrodes by an insulating polYlTIer layer prevented electrode break-down at the cost of puolping efficiency. Continuous punlping for 40 nlin at 20 fJ..,m s-l without detectable pump degradation was delTIOnstrated in this configuration.

Hansen, Thomas Steen; West, Keld

2007-01-01

343

Conductivity and optical studies of plasticized solid polymer electrolytes doped with carbon nanotube  

International Nuclear Information System (INIS)

Solid polymer electrolyte films based on Poly(ethylene oxide) (PEO) complexed with lithium hexafluorophosphate (LiPF6), ethylene carbonate (EC) and amorphous carbon nanotube (?CNTs) were prepared by the solution cast technique. The conductivity increases from 10-10 to 10-5 Scm-1 upon the addition of salt. The incorporation of EC and ?CNTs to the salted polymer enhances the conductivity significantly to 10-4 and 10-3 Scm-1. The complexation of doping materials with polymer were confirmed by X-ray diffraction and infrared studies. Optical properties like direct band gap and indirect band gap were investigated for pure and doped polymer films in the wavelength range 200-400 nm. It was found that the energy gaps and band edge values shifted to lower energies on doping. - Highlights: ? Optical band gap values show the decreasing trend with an increasing dopant concentration. ? It is also observed that the absorption edge shifted to longer wavelength on doping. ? Results of the optical measurements indicate the presence of a well-defined ???* transition associated with the formation of a conjugated C=O and/or C=O electronic structure.

2012-01-01

344

Conductivity and optical studies of plasticized solid polymer electrolytes doped with carbon nanotube  

Energy Technology Data Exchange (ETDEWEB)

Solid polymer electrolyte films based on Poly(ethylene oxide) (PEO) complexed with lithium hexafluorophosphate (LiPF{sub 6}), ethylene carbonate (EC) and amorphous carbon nanotube ({alpha}CNTs) were prepared by the solution cast technique. The conductivity increases from 10{sup -10} to 10{sup -5} Scm{sup -1} upon the addition of salt. The incorporation of EC and {alpha}CNTs to the salted polymer enhances the conductivity significantly to 10{sup -4} and 10{sup -3} Scm{sup -1}. The complexation of doping materials with polymer were confirmed by X-ray diffraction and infrared studies. Optical properties like direct band gap and indirect band gap were investigated for pure and doped polymer films in the wavelength range 200-400 nm. It was found that the energy gaps and band edge values shifted to lower energies on doping. - Highlights: > Optical band gap values show the decreasing trend with an increasing dopant concentration. > It is also observed that the absorption edge shifted to longer wavelength on doping. > Results of the optical measurements indicate the presence of a well-defined {pi}{yields}{pi}* transition associated with the formation of a conjugated C=O and/or C=O electronic structure.

Ibrahim, Suriani, E-mail: sue_83@um.edu.my [Advanced Materials Research Laboratory, Department of Mechanical Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia); Ahmad, Roslina; Johan, Mohd Rafie [Advanced Materials Research Laboratory, Department of Mechanical Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia)

2012-01-15

345

Smart Surface Chemistries of Conducting Polymers : for Guiding Cell Behavior in Polymeric Microsystems  

DEFF Research Database (Denmark)

In this thesis we investigate post-polymerization covalent modifications of poly(3,4-dioxythiophene (PEDOT)-type conducting polymers. The aim of the modifications is to gain specific control of the interaction between the material and living mammalian cells. The use of “click-chemistry” to modify an azide-modified PEDOT, poly(3,4-(1-azidomethylethylene)-dioxythiophene) (PEDOT-N3), is studied in detail, and found to be a valuable approach. This is concluded, as we are able to obtain delicate control of cellular adhesion, by covalently attaching appropriate bio-functional molecules onto PEDOT-N3 thin film substrates. Complementing these findings, we introduce a novel technique for fabricating surface chemical gradients on PEDOT-N3 substrates. The technique is based on applying “electro-click chemistry” to locally induce covalent modifications. Further supplementing these results, we develop a straightforward and in-expensive method for patterning conducting polymer thin films into microelectrodes, without losing control of the surface chemistry of the samples. On the contrary, the method provides direct control of the surface chemistry of both the fabricated micro-electrodes and the gaps between them. The method is based on locally removing PEDOTtype polymers to expose underlying non-conducting functional polymer substrates. Thereby, multifunctional substrates are obtained. By applying this method, we are able to fabricate allpolymer micro-systems with multiple types of localized functional (bio)-chemistries. In the course of our studies, we find that PEDOT-N3 thin films undergo a significant yet reversible swelling when exposed to dimethyl-sulfoxide (DMSO). This swelling is found to be of practical use for controlling the reaction density and depth. This, for example, enables the fabrication of dense poly-ethylene-glycol-coatings of the conducting polymer substrates. These coatings render the substrates resistant to protein adsorption. Hence, the choice of solvent is found to be a key parameter for achieving functional post-polymerization modifications of PEDOT-N3. The methods developed in this thesis are highly generic, and can therefore be applied for fabricating a diversity of microsystems based on conducting polymers, with multiple types of localized and highly bio-specific surfaces chemistries.

Lind, Johan Ulrik

2012-01-01

346

Preparation of Composite Polymer Electrolytes by Electrons-Induced Grafting: Proton and Lithium Conducting Membranes  

International Nuclear Information System (INIS)

Polymer electrolyte membranes (PEMs) are a class of materials that is receiving an increasing attention due to their applicability to a wide number of solid state devices and chemical processes. Proton (H+) and lithium ion (Li+) conducting membranes are of particular interest as both on increasing demand to prompt the commercialization of polymer electrolyte fuel cell and polymer electrolyte lithium battery. Radiation-induced grafting is a potential alternative method to prepare PEMs. During PEMs preparation, grafting reaction is often carried out using pre-irradiation method or simultaneous irradiation method (with ?-rays). However, reports on the use of simultaneous method with electron beam (EB) to prepare such membranes are very scarce. The objective of this work is to prepare and characterize two distinct polymer electrolyte membranes for possible use in fuel cell and lithium battery using single simultaneous radiation-induced grafting method with EB. Initially, styrene was impregnated into the porous structure of poly(vinylidene fluoride) (PVDF) films followed by simultaneous irradiation with EB using doses up to 50 kGy under N2 and at room temperature. Subsequently, the obtained polystyrene pore filled PVDF films (membrane precursor) were functionalized using two different chemical treatments. The first treatment includes sulfonation with chlorosulfonic acid/1,1,2,2-tetrachloroethanture to obtain H+ conducting composite membranes. The second treatment involves activation of the polystyrene pore filled PVDF films with LiPF6/EC/DC liquid electrolyte under to obtain Li+ conducting composite membranes. The micro-structure of both composite membranes was investigated using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The content of polystyrene grafted in the pores, water uptake, electrolyte uptake and ionic conductivity were measured. The obtained composite electrolyte membranes were found to achieve grafting yield up to 46% with superior Li+ conductivity values up to 1.9 10-3 S/cm when treated with LiPH6/EC/DC electrolyte solution and H+ conductivity of 5.95 x 10-2 S/cm when sulfonated with 10% chlorosulfonic acid. The results of this work suggests that simultaneous radiation-induced grafting with EB offers a single versatile root to prepare two high quality composite polymer electrolyte membranes conducting H+ and Li+ for possible use in fuel cell and lithium batteries, respectively.

2006-01-01

347

Li Ion Conducting Polymer Gel Electrolytes Based on Ionic Liquid/PVDF-HFP Blends.  

UK PubMed Central (United Kingdom)

Ionic liquids thermodynamically compatible with Li metal are very promising for applications to rechargeable lithium batteries. 1-methyl-3-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide (P(13)TFSI) is screened out as a particularly promising ionic liquid in this study. Dimensionally stable, elastic, flexible, nonvolatile polymer gel electrolytes (PGEs) with high electrochemical stabilities, high ionic conductivities and other desirable properties have been synthesized by dissolving Li imide salt (LiTFSI) in P(13)TFSI ionic liquid and then mixing the electrolyte solution with poly(vinylidene-co-hexafluoropropylene) (PVDF-HFP) copolymer. Adding small amounts of ethylene carbonate to the polymer gel electrolytes dramatically improves the ionic conductivity, net Li ion transport concentration, and Li ion transport kinetics of these electrolytes. They are thus favorable and offer good prospects in the application to rechargeable Li batteries including open systems like Li/air batteries, as well as more "conventional" rechargeable lithium and lithium ion batteries.

Ye H; Huang J; Xu JJ; Khalfan A; Greenbaum SG

2007-09-01

348

Li Ion Conducting Polymer Gel Electrolytes Based on Ionic Liquid/PVDF-HFP Blends.  

Science.gov (United States)

Ionic liquids thermodynamically compatible with Li metal are very promising for applications to rechargeable lithium batteries. 1-methyl-3-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide (P(13)TFSI) is screened out as a particularly promising ionic liquid in this study. Dimensionally stable, elastic, flexible, nonvolatile polymer gel electrolytes (PGEs) with high electrochemical stabilities, high ionic conductivities and other desirable properties have been synthesized by dissolving Li imide salt (LiTFSI) in P(13)TFSI ionic liquid and then mixing the electrolyte solution with poly(vinylidene-co-hexafluoropropylene) (PVDF-HFP) copolymer. Adding small amounts of ethylene carbonate to the polymer gel electrolytes dramatically improves the ionic conductivity, net Li ion transport concentration, and Li ion transport kinetics of these electrolytes. They are thus favorable and offer good prospects in the application to rechargeable Li batteries including open systems like Li/air batteries, as well as more "conventional" rechargeable lithium and lithium ion batteries. PMID:20354587

Ye, Hui; Huang, Jian; Xu, Jun John; Khalfan, Amish; Greenbaum, Steve G

2007-09-21

349

Reactive template synthesis of polypyrrole nanotubes for fabricating metal/conducting polymer nanocomposites.  

UK PubMed Central (United Kingdom)

Unique nanocomposites of polypyrrole/Au and polypyrrole/Pt hybrid nanotubes are synthesized employing polypyrrole (PPy) nanotubes as an advanced support by solution reduction. The conducting polymer PPy nanotubes are fabricated by using pre-prepared MnO2 nanowires as the reactive templates. MnO2 nanowires induce the 1D polymerization of pyrrole monomers and the simultaneous dissolution of the templates affords the hollow tube-like structure. The loading content of metal nanoparticles in the nanocomposites could be adjusted by simply changing the amount of metal precursors. This work provides an efficient approach to fabricate an important kind of metal/conducting polymer hybrid nanotubes that are potentially useful for electrocatalyst and sensor materials.

Zhang J; Liu X; Zhang L; Cao B; Wu S

2013-03-01

350

Li Ion Conducting Polymer Gel Electrolytes Based on Ionic Liquid/PVDF-HFP Blends  

Science.gov (United States)

Ionic liquids thermodynamically compatible with Li metal are very promising for applications to rechargeable lithium batteries. 1-methyl-3-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide (P13TFSI) is screened out as a particularly promising ionic liquid in this study. Dimensionally stable, elastic, flexible, nonvolatile polymer gel electrolytes (PGEs) with high electrochemical stabilities, high ionic conductivities and other desirable properties have been synthesized by dissolving Li imide salt (LiTFSI) in P13TFSI ionic liquid and then mixing the electrolyte solution with poly(vinylidene-co-hexafluoropropylene) (PVDF-HFP) copolymer. Adding small amounts of ethylene carbonate to the polymer gel electrolytes dramatically improves the ionic conductivity, net Li ion transport concentration, and Li ion transport kinetics of these electrolytes. They are thus favorable and offer good prospects in the application to rechargeable Li batteries including open systems like Li/air batteries, as well as more “conventional” rechargeable lithium and lithium ion batteries.

Ye, Hui; Huang, Jian; Xu, Jun John; Khalfan, Amish; Greenbaum, Steve G.

2009-01-01

351

Key role of the desolvation in the achievement of the quasi-metallic state of electronically conducting polymers  

Energy Technology Data Exchange (ETDEWEB)

Redox transformation of electronically conducting polymers was studied by different in situ combined electrochemical techniques. Results obtained with polypyrrole/dodecyl sulfate film in aqueous solution and with polythiophene/hexafluorophosphate films in acetonitrile by in situ ac conductance and EQCM support the assumption of the key role of the desolvation in the achievement of the so-called quasi-metallic state of electronically conducting polymers. The desolvation considered as a phase transition is the chemical background of the capacitive behaviour, and it causes the structural changes, which lead to a film in which the interchain interactions may form the large-scale conducting polymer matrix. (Author)

Krivan, E.; Visy, C. [Szeged Univ. (Hungary). Inst. of Physical Chemistry; Kankare, J. [Turku Univ. (Finland). Dept. of Chemistry

2005-01-15

352

Influence of electrically conductive polymers on the operating parameters of lead/acid batteries  

Energy Technology Data Exchange (ETDEWEB)

An investigation has been made of the possible application of electrically conductive polymers in efforts to improve the performance of lead/acid batteries. Results show that the new class of organic compounds may be used as modifiers of the active material to suppress self-discharge and irreversible sulfation and to increase the specific capacity of the battery, especially under automotive discharge rates and at low temperature. (orig.)

Dmitrenko, V.E.; Lubentsov, B.Z.; Yevdokimenko, S.G.; Lisyansky, I.I.; Soldatenko, V.A. [Electrozaryad Ltd., Galva Ltd., Moscow (Russian Federation)

1997-07-01

353

Impedance Study of Drinking Water and Tastants Using Conducting Polymer and Metal Electrodes  

Directory of Open Access Journals (Sweden)

Full Text Available In this study the sensing capabilities of a combination of metals and conducting polymer electrodes for drinking water and dissolved tastants using an AC-impedance mode in frequency range 102 to 105 Hz at 0.1 V potential has been carried out. Classification of seven different bottled and municipal drinking water samples along with various tastants dissolved in DI water(DI water) for KCl (5mM) (salty), HCl (5 mM) (sour) quinine (0.1 mM) (bitter), sucrose (5 mM) (sweet), black tea liquor, black tea liquor with sucrose (2% sugar solution), and a bottle of “packed” orange juice has been made using six different working electrodes in a multi electrode setup using PCA. Working electrodes of Platinum (Pt), Gold (Au), Silver (Ag), Glassy Carbon (GC) and conducting polymer electrodes of Polyaniline (PANI) and Polypyrrole (PPY) grown on an ITO surface potentiostatically have been deployed in a three electrode set up. The impedance response of these water samples using number of working electrodes shows a decrease in the real and imaginary impedance values presented on nyquist plots depending upon the nature of the electrode and amount of dissolved salts present in water/tastants. The different sensing surfaces allowed a high cross-selectivity in response to the same analyte. From PCA plots it was possible to classify drinking water in 3-4 classes using conducting polymer electrodes; however tastants were well separated from the PCA plots employing the impedance data of both conducting polymer and metal electrodes.

Mopsy Dhiman,; Pawan Kapur; Ganguli; Madan Lal Singla

2012-01-01

354

Impedance study of tea with added taste compounds using conducting polymer and metal electrodes.  

UK PubMed Central (United Kingdom)

In this study the sensing capabilities of a combination of metals and conducting polymer sensing/working electrodes for tea liquor prepared by addition of different compounds using an impedance mode in frequency range 1 Hz-100 KHz at 0.1 V potential has been carried out. Classification of six different tea liquor samples made by dissolving various compounds (black tea liquor + raw milk from milkman), (black tea liquor + sweetened clove syrup), (black tea liquor + sweetened ginger syrup), (black tea liquor + sweetened cardamom syrup), (black tea liquor + sweet chocolate syrup) and (black tea liquor + vanilla flavoured milk without sugar) using six different working electrodes in a multi electrode setup has been studied using impedance and further its PCA has been carried out. Working electrodes of Platinum (Pt), Gold (Au), Silver (Ag), Glassy Carbon (GC) and conducting polymer electrodes of Polyaniline (PANI) and Polypyrrole (PPY) grown on an ITO surface potentiostatically have been deployed in a three electrode set up. The impedance response of these tea liquor samples using number of working electrodes shows a decrease in the real and imaginary impedance values presented on nyquist plots depending upon the nature of the electrode and amount of dissolved salts present in compounds added to tea liquor/solution. The different sensing surfaces allowed a high cross-selectivity in response to the same analyte. From Principal Component Analysis (PCA) plots it was possible to classify tea liquor in 3-4 classes using conducting polymer electrodes; however tea liquors were well separated from the PCA plots employing the impedance data of both conducting polymer and metal electrodes.

Dhiman M; Kapur P; Ganguli A; Singla ML

2012-09-01

355

Electro-generated conducting polypyrrole polymers and applications in photoelectrochemical cells  

Energy Technology Data Exchange (ETDEWEB)

A major problem in the development of photoelectrochemical cells for solar energy conversion and storage is the susceptibility of small bandgap semiconductor materials to photodegradation. This problem could be overcome, in principle, by protecting the semiconductor electrode surface with electrically conducting polymer film. This film, acting as a barrier to ion/solvent transport, would inhibit photodegradation of the electrode surface while permitting electron exchange with the electrode. Recent studies on the electrogenerated polypyrrole and its applications in photoelectrochemical cells are presented.

Noufi, R.N.

1983-01-01

356

A facile avenue to conductive polymer brushes via cyclopentadiene-maleimide Diels-Alder ligation.  

Science.gov (United States)

Cyclopentadienyl end-capped poly(3-hexylthiophene) was employed to fabricate conductive surface tethered polymer brushes via a facile route based on cyclopentadiene-maleimide Diels-Alder ligation. The efficient nature of the Diels-Alder ligation was further combined with a biomimetic polydopamine-assisted functionalization of surfaces, making it an access route of choice for P3HT surface immobilization. PMID:23945828

Yameen, Basit; Rodriguez-Emmenegger, Cesar; Preuss, Corinna M; Pop-Georgievski, Ognen; Verveniotis, Elisseos; Trouillet, Vanessa; Rezek, Bohuslav; Barner-Kowollik, Christopher

2013-08-29

357

Electroanalysis of NADH Using Conducting and Redox Active Polymer/Carbon Nanotubes Modified Electrodes-A Review  

Directory of Open Access Journals (Sweden)

Full Text Available Past few decades, conducting and redox active polymers play a critical role in the development of transducers for biosensing. It has been evidenced by increasing numerous reports on conducting and redox active polymers incorporated electrodes for assay of biomolcules. This review highlights the potential uses of electrogenerated polymer modified electrodes and polymer/carbon nanotubes composite modified electrodes for electroanalysis of reduced form of nicotinamide adenine dinuceltoide (NADH). In addition, carbon electrodes modified with organic and inorganic materials as modifier have been discussed in detail for the quantification of NADH based on mediator or mediator-less methods.

S. Ashok Kumar; Shen-Ming Chen

2008-01-01

358

Molecule recognition sensor using electrically conductive polymer; Dodensei kobunshi ni yoru bunshi ninshiki sensor  

Energy Technology Data Exchange (ETDEWEB)

This paper describes a molecule recognition sensor using electrically conductive polymers. Such conjugated system molecules as polythiophene and polypyrrole are known as electrically conductive polymers because they have relatively free {pi} electrons. Regioregular polythiophenes can cause conformational change in the main chain due to poor solvent and heat, and change in color and electrical properties. With water soluble regioregular polythiophene having carboxylate as the side chain, increasing the ion pair caused twist in the conformation of the main chain, changing the color from purple to yellow. When a sensor is made by covalently bonding electrolytically polymerized membrane of polypyrrole with oligo DNA, this membrane presents an oxidization peak at -0.2V in 0.5 M NaCl, but the peak current value has decreased in association with addition of complementary oligo DNA. Very little change was observed when non-complementary oligo DNA was added. Such a molecule recognition sensor is simple, inexpensive and interesting that utilizes the conductive polymer having a character of changing the color and electrical properties when it is subjected to any perturbation from outside. (NEDO)

Matsuura, K. [Nagoya University, Nagoya (Japan)

1999-01-01

359

Synthesis and proton conductivity studies of doped azole functional polymer electrolyte membranes  

International Nuclear Information System (INIS)

The development of anhydrous proton-conducting membranes is important for the operation of polymer electrolyte membrane fuel cell (PEMFC) at intermediate temperature (100-200 oC). In this work, poly(vinylbenzylchloride), PVBC was produced by free radical polymerization of 4-vinylbenzylchloride and then it was modified with 5-aminotetrazole (ATET) to obtain poly(vinylbenzylaminotetrazole), PVBC-ATET. The composition of the polymer was verified by elemental analysis (EA) and the structure was characterized by FT-IR and 13C NMR spectra. According to the elemental analysis result, PVBC was modified by ATET with 80% yield. The polymer was doped with trifluoromethanesulfonic acid (TA) at various molar ratios, x = 1.25, 2.5, 3.75 with respect to tetrazole unit. The proton transfer from TA to the tetrazole rings was proved with FT-IR spectroscopy. Thermogravimetry (TG) analysis showed that the samples are thermally stable up to approximately 200 oC. Differential scanning calorimetry (DSC) results illustrated the homogeneity of the materials. Cyclic voltammetry (CV) study illustrated that the electrochemical stability domain for PVBC-ATET-TA2.5 extends over 3.0 V. The proton conductivity of these materials increased with dopant concentration and the temperature. Maximum proton conductivity of PVBC-ATET-TA2.5 was found to be 0.01 S/cm at 150 oC in the anhydrous state.

2010-12-01

360

Electrical Conductivity in the Nonconjugated Polymer Styrene-Butadiene-Rubber (SBR)  

Science.gov (United States)

Electrical conductivity as a function of doping with iodine has been measured in a nonconjugated polymer, styrene-butadiene-rubber (SBR) which is a copolymer of styrene and butadiene, used extensively in automobile tires. The conductivity reaches a value of about 0.01 S/cm upon doping with iodine. The color of the rubber film changes from colorless to black upon doping. FTIR studies of the polymer show that the intensity of the =CH bending mode decreases with doping - indicating that the dopant interacts with the double bond and leads to a charge-transfer from the double bond to the dopant. The absorption spectrum after doping at a low level has two peaks - one at 4.13 eV and the other at 3.18 eV. The first peak is due to the cation radical formed upon doping and the second one is due to the charge-transfer complex formed with the dopant. The polystyrene segments of the copolymer seem to have less interaction with the dopant since polystyrene is glassy. The radical cation peak of another nonconjugated conductive polymer, polyalloocimene having a higher number-fraction of double bonds in the repeat, is slightly red-shifted compared to that of SBR.

Titus, Jitto; Khatavkar, Sanchit; Thakur, Mrinal

2003-03-01

 
 
 
 
361

Experimental investigations of an ionic-liquid-based, magnesium ion conducting, polymer gel electrolyte  

Energy Technology Data Exchange (ETDEWEB)

Studies on a novel magnesium ion conducting gel polymer electrolyte based on a room temperature ionic liquid (RTIL) is reported. It comprises a Mg-salt, Mg(CF{sub 3}SO{sub 3}){sub 2} [or magnesium triflate, Mg(Tf){sub 2}] solution in an ionic liquid, 1-ethyl-3-methylimidazolium trifluoro-methanesulfonate (EMITf), immobilized with poly(vinylidene fluoride-hexafluoropropylene) (PVdF-HFP), which is a freestanding, semitransparent and flexible film with excellent mechanical strength. Physical and electrochemical analyses demonstrate promising characteristics of these films, suitable as electrolytes in rechargeable magnesium batteries. The material offers a maximum electrical conductivity of {proportional_to}4.8 x 10{sup -3} S cm{sup -1} at room temperature (20 C) with excellent thermal and electrochemical stabilities. Possible conformational changes in the polymer host PVdF-HFP due to ionic liquid solution entrapment and ion-polymer interaction are investigated by Fourier transform infra-red (FTIR), X-ray diffraction (XRD) and scanning electron microscopic (SEM) methods. The Mg{sup 2+} ion transport in the gel film is confirmed from cyclic voltammetry, impedance and transport number measurements. The Mg{sup 2+} ion transport number (t{sub +}) is {proportional_to}0.26, which indicates a substantial contribution of triflate anion transport along with ionic conduction due to the component ions of the ionic liquid. (author)

Pandey, G.P.; Hashmi, S.A. [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India)

2009-02-15

362

[Ion-conducting mechanism of composite polymer electrolyte: an emission FTIR spectroscopy study].  

UK PubMed Central (United Kingdom)

Solvent-free, composite electrolytes based on poly(ethylene oxide) (PEO) were prepared by using mesoporous silica SBA-15 with surface modification of (trimethylchlorosilane) as the filler. The samples were explored by emission FTIR spectroscopy at elevated temperatures. The results of emission FTIR spectra illustrated the dependence of crystalline PEO phase on temperature. On the basis of electrochemistry, SEM, and emission FTIR studies, the effect of inorganic filler on the ionic conductivity was analyzed, and a conclusion concerning the ion-conducting mechanism of composite polymer electrolyte was drawn. The exploratory experiments demonstrated that the emission FTIR spectroscopy is an important method to be applied in the study of lithium batteries.

Xu JM; Jiang YX; Zhuang QC; Zeng DM; Sun SG

2007-02-01

363

Ionically conductive thin polymer films prepared by plasma polymerization. Pt. 7. Preparation and characterization of solid polymer electrolyte having fixed carboxylic acid groups with single mobile species  

Energy Technology Data Exchange (ETDEWEB)

Ultra-thin, uniform, pinhole-free solid polymer electrolyte films having a fixed carboxylic ester group of approximately 1 {mu}m thickness were prepared by polymerization of methyl acrylate and tris(2-methoxyethoxy)vinylsilane in a glow discharge plasma. The carboxylic ester group of the plasma polymer were transformed to lithium carboxylate groups by treatment with lithium iodide. This process give a single lithium ion conductive film. These solid polymer electrolyte films showed ionic conductivities of the order of 10{sup -8} S cm{sup -1} (10{sup 4} {omega} cm{sup 2} resistance per unit area) at room temperature. (orig.).

Uchimoto, Yoshiharu; Ogumi, Zempachi; Takehara, Zenichiro (Dept. of Industrial Chemistry, Kyoto Univ., Yoshida (Japan))

1990-08-01

364

Towards TiO2-conducting polymer hybrid materials for lithium ion batteries  

International Nuclear Information System (INIS)

[en] Nanocomposites of TiO2 (anatase) with polypyrrole (Ppy) or poly(3,4-ethylenedioxythiophene) (PEDOT) were prepared via electrochemical routes. The deposition process of the conducting polymer films was performed in the presence of perchlorate, p-toluenesulphonate (TOS) or bis(trifluoromethylsulphonyl)imide (TFSI) anions in propylene carbonate (PC). The obtained electrode materials were characterized using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). An improvement of lithium ion intercalation/de-intercalation properties of titanium(IV) oxide as a result of its interfacing with the polymers is evidenced. This effect was strongly dependent on the thickness of the polymer layer and closely related to the polymer facility for transporting of lithium ion. Polypyrrole properties, in contrast to the PEDOT case, are very sensitive to selection of the substrate material (Pt or Pt/TiO2) during electropolymerization. Polypyrrole deposited on a rough surface exhibits an improvement in its ion exchange abilities. The impact of underlying TiO2 layers on Ppy properties has an indirect (synergic) influence on the effectiveness of lithium ion intercalation into the oxide too. The properties of the composites were discussed also in view of the comparative electrochemical quartz crystal microbalance (EQCM) study focussing on ion transport properties of Ppy and PEDOT.

2010-03-30

365

Nonaligned carbon nanotubes partially embedded in polymer matrixes: a novel route to superhydrophobic conductive surfaces.  

UK PubMed Central (United Kingdom)

A new method for transforming common polymers into superhydrophobic conductive surfaces, with both a high static water contact angle (approximately 160 degrees) and a low sliding angle (2.0 degrees-4.5 degrees), and a low sheet resistance on the order of 10(1)-10(3) ohms/sq is presented. A layer of multiwalled carbon nanotubes (MWNTs) is first distributed on the surface of a polymer substrate, then by a single step of pressing, the MWNTs are partially embedded inside the substrate surface and form a superhydrophobic coating with a "carpet-" or "hair"-like morphology. The infiltration of polymer melts into the porous MWNT layer follows Darcy's law, and the pressing time greatly influence the morphology and superhydrophobicity. Moreover, the coating can be electrically heated by 20-70 degrees C with a voltage as low as 4-8 V at an electric energy density below 1.6 J/cm(2) and therefore can be used for deicing applications. Hydroxylation and fluoroalkylsilane treatment can greatly improve the stability of the superhydrophobicity of MWNTs. This method is convenient and applicable to a variety of thermoplastic polymers and nonpolymer substrates coated by silicone rubber.

Peng M; Liao Z; Qi J; Zhou Z

2010-08-01

366

Conductive polymer/high-TC superconductor sandwich structures: An example of a molecular switch for controlling superconductivity  

International Nuclear Information System (INIS)

The preparation of a hybrid conducting polymer/high-temperature superconductor device consisting of a polypyrrole coated YBa2Cu3O7-x microbridge is reported. Electrochemical techniques are exploited to alter the oxidation state of the polymer and, in doing so, it is found for the first time that superconductivity can be modulated in a controllable and reproducible fashion by a polymer layer. Whereas the neutral (insulating) polypyrrole only slightly influences the electrical properties of the underlying YBa2Cu3O7- film, the oxidized (conductive) polymer depresses Tc by up to 50K. In a similar fashion, the oxidation state of the polymer is found to modulate reversibly the magnitude of Jc, the superconducting critical current. Thus, a new type of molecular switch for controlling superconductivity is demonstrated. Electrochemical, resistance vs. temperature, atomic force microscopy and scanning electron microscopy measurements are utilized to explore the polymer/superconductor interactions.

1994-01-01

367

Study of EVOH based single ion polymer electrolyte. Composition and microstructure effects on the proton conductivity  

Energy Technology Data Exchange (ETDEWEB)

A comb-like EVOH based single ion polymer electrolyte (EVOH-g-SPEG) was synthesized by sulfonification of EVOH grafts 2-(2-chloroethoxy) ethanol (C{sub 4}H{sub 9}O{sub 2}Cl)/2-[2-(2-chloroethxy) ethoxy] ethanol (C{sub 6}H{sub 13}O{sub 3}Cl) with 1, 3-propane sultone. The main chain of the comb-like polymer is hydrophobic polyethylene segments; the side chain is hydrophilic poly (ethylene glycol) (PEG) segment, which can solubilize large amounts of inorganic salts. The sulfonic acid group was introduced onto the end of the PEG side chain. The acid form of SPE was successfully obtained by being dialyzed from the products with acid solution. The saturation water sorption of EVOH-g-SPEG membrane increased with the side chain length and the immersion time. The XRD results indicate that the water in SPE membrane region can destroy the membrane crystalline structure and the water absorption membranes are nearly amorphous. AFM phase images of the hydration membranes clearly show the hydrophilic domains, with sizes increasing from 10 to 35 nm as a function of the side chain length. A phase inversion could be observed when n>=5, which was consistent with a rapid increase in water absorption. And the ion conductivity is also measured by AC impedance. The conductivity is greatly influenced by ion exchange capacity and water sorption. The comb-like EVOH-g-SPEG polymer electrolyte grafts with 2 PEG side chain provides the highest ionic conductivity (1.65x10{sup -3} S cm{sup -1}). The comb-like polymer could be a candidate as new polymeric electrolyte material for fuel cells and other electrochemical devices. (author)

Zhang, Yu-jun; Huang, Yu-dong [Department of Applied Chemistry, Harbin Institute of Technology, P.O. Box 410, Xidazhi Street 92, Nangang District, Harbin 150001 (China); Wang, Lei [School of Materials Science and Engineering, Harbin University of Science and Technology, P.O. Box. 3491, Linyuan Road 4, Dongli District, Harbin 150040 (China)

2006-01-16

368

Investigation on Photovoltaic Performance based on Matchstick-Like Cu2S–In2S3Heterostructure Nanocrystals and Polymer  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract In this paper, we synthesized a novel type II cuprous sulfide (Cu2S)–indium sulfide (In2S3) heterostructure nanocrystals with matchstick-like morphology in pure dodecanethiol. The photovoltaic properties of the heterostructure nanocrystals were investigated based on the blends of the nanocrystals and poly(2-methoxy-5-(2?-ethylhexoxy)-p-phenylenevinylene) (MEH-PPV). In comparison with the photovoltaic properties of the blends of Cu2S or In2S3nanocrystals alone and MEH-PPV, the power conversion efficiency of the hybrid device based on blend of Cu2S–In2S3and MEH-PPV is enhanced by ~3–5 times. This improvement is consistent with the improved exciton dissociation or separation and better charge transport abilities in type II heterostructure nanocrystals.

Tang Aiwei; Teng Feng; Wang Yan; Hou Yanbing; Han Wei; Yi Luoxin; Gao Mingyuan

2008-01-01

369

Fast prototyping of conducting polymer microelectrodes using resistance-controlled high precision drilling  

DEFF Research Database (Denmark)

We present a straightforward method for fast prototyping of microelectrode arrays in the highly conductive polymer poly(3,4-ethylenedioxythiophene) (PEDOT). Microelectrode arrays were produced by electrical resistance-controlled microdrilling through an insulating polymer layer (TOPAS® 5013) covering a PEDOT layer. The sudden drop in electrical resistance between the metal drill and the PEDOT layer upon physical contact was employed as stop criterion for the drilling process. Arrays of 3×3 microelectrodes of diameter 30?m or 100?m, respectively, and having center-to-center electrode spacings of 130?m and 300?m, respectively, were fabricated. Their functionality was verified by chronoamperometry on potassium ferro-/ferricyanide. Comparison of the experimentally obtained results to finite element modeling of the respective electrode configurations shows that the conducting polymer electrodes approach the steady state currents predicted from modeling, but at a much slower rate than expected. This is shown to be caused by the use of electroactive PEDOT electrodes. Subtraction of the latter contribution gives approach to steady state currents within a few seconds, which is in very good agreement with the modeled response time.

Kafka, Jan Robert; Geschke, Oliver

2011-01-01

370

Light-triggered conducting properties of a random carbon nanotubes network in a photochromic polymer matrix  

Science.gov (United States)

Photochromic materials reversibly change their colour due to a photochemical reaction that takes place when the material is irradiated with photons of suitable energy. This peculiar feature has been extensively exploited to develop smart sunglasses, filters and inks. With a proper molecular design it is possible to enable modulation not only of colour but also of other properties such as refractive index, dipole moment, nonlinear optical properties or conductivity by a photoswitching of the molecular structure. The approach herein developed consists in modifying, upon irradiation, the properties of a molecular component coupled with the photochromic molecule. In particular, the switching features of photochromic systems are matched with the intriguing peculiar properties of carbon nanotubes (CNTs). A photochromic polyester has been properly synthesised to be used as switching polymer matrix coupled with a network of CNTs. Irradiation of the polymer/CNTs blend results into a light-triggered conductance switching. The reversible electrocyclization of the polymer under UV-vis illumination results into a modification of the inter-tube charge mobility, and accordingly, of the overall resistance of the blend. Solution techniques allow us to obtain blended films with sheet resistance modulation larger than 150%, good thermal stability and fatigue resistance at room conditions, in an easier, faster and scalable way as respect to the single-molecule approach.

Castagna, R.; Sciascia, C.; Srimath Kandada, A. R.; Meneghetti, M.; Lanzani, G.; Bertarelli, C.

2011-09-01

371

Dielectric properties and conductivity of carbon nanofiber/semi-crystalline polymer composites  

International Nuclear Information System (INIS)

The properties of semi-crystalline polymer nanocomposites are affected by the nanofillers directly and indirectly, as two phases, i.e., crystalline and amorphous, exist in the polymer. The effects of nanofillers on the two phases could be competitive. The dielectric properties and conductivity of carbon nanofibers (CNF)/semi-crystalline polymer nanocomposites are studied in this paper. CNF/polypropylene (PP) nanocomposites are prepared in experiment by melt blending. The resulting morphology and crystalline structure are characterized by means of differential scanning calorimetry, wide angle X-ray diffraction and scanning electron microscopy. The PP nanocomposite containing 5 wt.% CNF exhibits a surprisingly high dielectric constant under wide sweep frequencies attended by low dielectric loss. Its dielectric constant is >600 under lower frequency, and remains >200 at a frequency of 4000 Hz. The electrical and thermal conductivities of the nanocomposites are studied, and enhancements are seen with increased CNF content. Theoretical analyses on the physical properties are carried out by applying the existing models. Research results indicate that a common commercial plastic with good comprehensive performance, which exhibited the potential for applications in advanced electronics, was obtained by a simple industry benign technique.

2008-01-01

372

An atomic level analysis of conductivity and strength in poly(ethylene oxide) sulfonic acid-based solid polymer electrolytes  

International Nuclear Information System (INIS)

The structure, ionic conductivity and strength of poly(ethylene oxide) (PEO) sulfonic acid-based solid polymer electrolytes with various contents of the PEO polymer are analyzed using molecular dynamics simulations. To quantify the electrolyte structure, comprehensive coordination and dimensional analyses are carried out. Ionic conductivity is determined by computing the Einstein-diffusion based conductivity for all ionic particles in the system. The strength of the electrolyte is quantified by carrying out a set of molecular simulations of the uniaxial deformation process under constant stress-rate conditions. The results obtained indicate that increased hydration improves the ionic conductivity, but degrades the strength in solid polymer electrolytes at hand. In addition, it appears that there is an optimal level of the PEO polymer content in these materials, which at the same hydration level, yields the best combination of ionic conductivity and strength.

2005-03-15

373

Transparent conducting hybrid thin films fabricated by layer-by-layer assembly of single-wall carbon nanotubes and conducting polymers  

Energy Technology Data Exchange (ETDEWEB)

The effect of conducting polymers on the performance of transparent conducting SWNT thin films fabricated by the layer-by-layer (LBL) assembly has been investigated. Transparent conducting SWNT thin films were fabricated by the LBL assembly in two ways, one using conducting polymers, PEDOT-PEG, and the other using non-conducting polymers, PAH, and their electrical and optical properties were compared. The sheet resistance of (PSS-SWNT/PEDOT-PEG){sub n} films is more than thrice lower than that of (PSS-SWNT/PAH){sub n} films for the same n while the decrease of optical transmittance due to the absorbance of PEDOT-PEG is fairly small (ca. 2 % at n=30). The conductivity ratio of the (PSS-SWNT/PEDOT-PEG){sub 30} is 3.3 times larger than that of the (PSS-SWNT/PAH){sub 30}. These figures indicate that the performance of the transparent conducting SWNT thin films fabricated by the LBL assembly is highly improved by using conducting polymers instead of non-conducting ones. (orig.)

Sim, Jun-Bo; Lee, Min-Jae; Choi, Sung-Min [Korea Advanced Institute of Science and Technology, Department of Nuclear and Quantum Engineering, Daejeon (Korea, Republic of); Yang, Hyun-Ho; Yoon, Jun-Bo [Korea Advanced Institute of Science and Technology, Department of Electrical Engineering, Daejeon (Korea, Republic of)

2012-08-15

374

Effect of casting solvent interactions on proton conductivity in sulfonated polymer (PEEK) proton exchange membranes  

International Nuclear Information System (INIS)

The proton conductivity of solvent-cast proton exchange membranes (PEM) prepared from sulfonated poly(ether ether ketone) (SPEEK) was found to be sensitive to the choice of casting solvent and the membrane drying conditions. Using proton nuclear magnetic resonance (NMR) spectroscopy, several factors were shown to affect proton conductivity in PEMs. NMR revealed the formation of strong interactions between SPEEK polymer and the casting solvents dimethylformamide (DMF) and dimethyl cetamide (DMAc), commonly used in PEM preparation. DMF readily hydrogen-bonds with the polymers' sulfonic acid groups starting at temperatures as low as 60oC. However, DMAc is much less susceptible to hydrogen bonding, which occurs only above 100oC. Both DMF and DMAc solvent interactions with SPEEK during PEM preparation significantly affect the proton conductivity properties. In addition, both solvents are prone to thermal decomposition resulting in dimethylamine which also strongly hydrogen-bonds with SPEEK. The presence of residual sulfuric acid originating from SPEEK preparation has a catalytic effect on the thermal degradation of DMF and DMAc. Under high temperature treatment of films, residual sulfuric acid reacts with both DMF and DMAc, causing their degradation resulting in the formation of N,N-dimethylaminium hydrogensulfate which is also believed to have a negative effect on proton conductivity. (author)

2003-01-01

375

Thermoelectric behavior of conducting polymers: On the possibility of off-diagonal thermoelectricity  

Energy Technology Data Exchange (ETDEWEB)

Non-cubic materials, when structurally aligned, possess sufficient anisotropy to exhibit thermoelectric effects where the electrical and thermal paths can be orthogonal due to off-diagonal thermoelectricity (ODTE). The authors discuss the benefits of this form of thermoelectricity for device applications and describe a search for suitable thermoelectric properties in the air-stable conducting polymers polyaniline and polypyrrole. They find, at 300K for diagonal (ordinary) thermoelectricity (DTE), the general correlation that the logarithm of the electrical conductivity varies linearly with the Seebeck coefficient on doping, but with a proportionality in excess of a prediction from theory. The correlation is unexpected in its universality and unfavorable in its consequences for applications in DTE and ODTE. A standard model suggests that conduction by carriers of both signs occurs in these polymers, which thus leads to reduced thermoelectric efficiency. They also discuss polyacetylene (which is not air-stable), where this ambipolar conduction does not occur, and where properties seem more favorable for thermoelectricity.

Mateeva, N.; Testardi, L. [TecOne, Inc., Tallahassee, FL (United States); Niculescu, H. [TecOne, Inc., Tallahassee, FL (United States)]|[Florida A and M Univ./Florida State Univ., Tallahassee, FL (United States) Coll. of Engineering; Schlenoff, J. [TecOne, Inc., Tallahassee, FL (United States)]|[Florida State Univ., Tallahassee, FL (United States). Chemistry Dept.

1998-12-01

376

Photomodulation spectroscopy of photocarrier dynamics, electronic defects and morphology of conducting polymers  

Energy Technology Data Exchange (ETDEWEB)

This is a progress report on the second period of activities associated with the DOE grant to the Physics Department of the University of Utah, starting on April 1st, 1991, on photocarrier dynamics, electronic defects and morphology of conducting polymers using the photomodulation spectroscopy. During the second period of this grant we have achieved impressive results and have started new studies, to be completed during the grant continuation period of the third year. We will describe our progress according to the material studied, since this is the best method to summarize our accomplishments. We have used a variety of techniques in our studies such as: CW photomodulation, photomodulation in the femtosecond and picosecond time ranges, CW resonant Raman scattering, transient photoinduced Raman scattering, electro-absorption, degenerate four-wave mixing and the newly technique of spin dependent photomodulation. These techniques have been used to obtain the transient electronic response of the studied conducing polymers.

Vardeny, Z.V.

1991-10-08

377

Photomodulation spectroscopy of photocarrier dynamics, electronic defects and morphology of conducting polymers. Progress report  

Energy Technology Data Exchange (ETDEWEB)

This is a progress report on the second period of activities associated with the DOE grant to the Physics Department of the University of Utah, starting on April 1st, 1991, on photocarrier dynamics, electronic defects and morphology of conducting polymers using the photomodulation spectroscopy. During the second period of this grant we have achieved impressive results and have started new studies, to be completed during the grant continuation period of the third year. We will describe our progress according to the material studied, since this is the best method to summarize our accomplishments. We have used a variety of techniques in our studies such as: CW photomodulation, photomodulation in the femtosecond and picosecond time ranges, CW resonant Raman scattering, transient photoinduced Raman scattering, electro-absorption, degenerate four-wave mixing and the newly technique of spin dependent photomodulation. These techniques have been used to obtain the transient electronic response of the studied conducing polymers.

Vardeny, Z.V.

1991-10-08

378

A temperature study of the ionic conductivity of a hybrid polymer electrolyte  

Energy Technology Data Exchange (ETDEWEB)

The ionic conductivity of a hybrid polymer electrolyte was investigated as a function of temperature and salt concentration and compared to the corresponding liquid electrolyte. The hybrid polymer electrolyte was based on a radiation induced cross-linked polyether network with propylene carbonate in an interpenetrating liquid phase and LiAsF{sub 6} as electrolyte salt. The temperature behavior was best explained by the Vogel-Tamman-Fulcher relation. The activation energy was found to decrease with salt concentration, whereas the apparent glass-transition temperature increased. At 0.08 mol/kg LiAsF{sub 6}, the real glass-transition temperature was found to be 60 K higher than the apparent glass-transition temperature, but at 2.52 mol/kg LiAsF{sub 6} no difference was found.

Olsen, I.I.; Koksbang, R. [Valence Technology, Inc., Henderson, NV (United States)

1996-02-01

379

Molecularly imprinted conducting polymer based electrochemical sensor for detection of atrazine.  

UK PubMed Central (United Kingdom)

An original electrochemical sensor based on molecularly imprinted conducting polymer (MICP) is developed, which enables the recognition of a small pesticide target molecule, atrazine. The conjugated MICP, poly(3,4-ethylenedioxythiophene-co-thiophene-acetic acid), has been electrochemically synthesized onto a platinum electrode following two steps: (i) polymerization of comonomers in the presence of atrazine, already associated to the acetic acid substituent through hydrogen bonding, and (ii) removal of atrazine from the resulting polymer, which leaves the acetic acid substituents open for association with atrazine. The obtained sensing MICP is highly specific towards newly added atrazine and the recognition can be quantitatively analyzed by the variation of the cyclic voltammogram of MICP. The developed sensor shows remarkable properties: selectivity towards triazinic family, large range of detection (10(-9) mol L(-1) to 1.5 x 10(-2) mol L(-1) in atrazine) and low detection threshold (10(-7) mol L(-1)).

Pardieu E; Cheap H; Vedrine C; Lazerges M; Lattach Y; Garnier F; Remita S; Pernelle C

2009-09-01

380

Molecularly imprinted conducting polymer based electrochemical sensor for detection of atrazine.  

Science.gov (United States)

An original electrochemical sensor based on molecularly imprinted conducting polymer (MICP) is developed, which enables the recognition of a small pesticide target molecule, atrazine. The conjugated MICP, poly(3,4-ethylenedioxythiophene-co-thiophene-acetic acid), has been electrochemically synthesized onto a platinum electrode following two steps: (i) polymerization of comonomers in the presence of atrazine, already associated to the acetic acid substituent through hydrogen bonding, and (ii) removal of atrazine from the resulting polymer, which leaves the acetic acid substituents open for association with atrazine. The obtained sensing MICP is highly specific towards newly added atrazine and the recognition can be quantitatively analyzed by the variation of the cyclic voltammogram of MICP. The developed sensor shows remarkable properties: selectivity towards triazinic family, large range of detection (10(-9) mol L(-1) to 1.5 x 10(-2) mol L(-1) in atrazine) and low detection threshold (10(-7) mol L(-1)). PMID:19699400

Pardieu, Elodie; Cheap, Helene; Vedrine, Christophe; Lazerges, Mathieu; Lattach, Youssef; Garnier, Francis; Remita, Samy; Pernelle, Christine

2009-07-15

 
 
 
 
381

Studies on water soluble conducting polymer. Aniline initiated polymerization of m-aminobenzene sulfonic acid  

Energy Technology Data Exchange (ETDEWEB)

The synthesis of poly(m-aminobenzene sulfonic acid) homopolymer (PABS), by aniline initiated polymerization of m-aminobenzene sulfonic acid using ammonium persulfate oxidation has been attempted. The water soluble polymer PABS thus synthesized was characterized by IR, UV, TG-DSC, {sup 1}H-NMR, SEM and ESR spectroscopic techniques. A co-ordinated IR and thermal analysis (TG, DSC) indicate that thermal desulfonation occurs preferentially in PABS-Na compared to PABS, commencing at 310 C and 370 C, respectively. The steric hindrance due to the large ortho substitution causes lowering of conductivity of PABS and its Na-salt which was found to be 5.4 x 10{sup -5} S/cm and 2.4 x 10{sup -6} S/cm, respectively. The ESR spectra show that the polymer to be strongly paramagnetic with a g value of 2.0013. (orig.) 23 refs.

Roy, B.C.; Gupta, M.D.; Bhowmik, L.; Ray, J.K. [Indian Inst. of Tech., Kharagpur (India). Dept. of Chemistry

1999-04-12

382

Analysis of hysteresis phenomenon as observed from voltammetric data of conducting polymers: part I  

Directory of Open Access Journals (Sweden)

Full Text Available The hysteresis phenomenon inherent to redox processes of Electronic Conducting Polymers (ECP) has been studied. Hysteresis was divided into two classes: i) dynamic hysteresis, containing a kinetic and an ohmic component and ii) stationary or thermodynamic hysteresis. A mathematical analysis was performed on the dynamic hysteresis observed in cyclic voltammograms of two polymers: polyaniline (PANI) and poly(3-methylthiophene) (P3MT). It has been shown that in the case of P3MT, the hysteresis is mainly kinetic due to the rate of one of the steps of the redox process. However, an ohmic component related to the existence of an electrical impedance in series with the electrochemical system is also present. As for PANI, hysteresis is current independent, which is characteristic of thermodynamic hysteresis.

Matencio Tulio; Pernaut Jean Michel; Vieil Eric

2003-01-01

383

Chemical synthesis of water-soluble, chiral conducting-polymer complexes  

Energy Technology Data Exchange (ETDEWEB)

The template-guided synthesis of water-soluble, chiral conducting polymer complexes is described. Synthesis of water-soluble polyaniline complexes is achieved by carefully controlling the experimental parameters such as; acid concentration, ionic strength, monomer/template ratio, total reagent concentration, and order of reagent addition. Chiral (helical) polyaniline complexes can be synthesized by addition of a chiral inducing agent (chiral acid) prior to polymerization, and the polyaniline helix can be controlled by the addition of the (+) or (-) form of the chiral acid. Moreover the quantity of chiral acid and the salt content has a significant impact on the degree of chirality in the final polymer complexes. The polyaniline and the template have been found to be mixed at the molecular level which results in chiral complexes that are robust through repeated doping and dedoping cycles.

Wang, Hsing-Lin (Los Alamos, NM); McCarthy, Patrick A. (Oakland, CA); Yang, Sze Cheng (Wakefield, RI)

2003-01-01

384

Electrochemical co-deposition of conductive polymer-silica hybrid thin films.  

UK PubMed Central (United Kingdom)

Conductive polymers, such as polypyrrole (ppy), have been the subject of numerous studies due to their promising applications in organic solar cells, flexible electronics, electrochromic devices, super capacitors, etc. Yet, their application is still limited as a result of poor processability. Silica has been reported to improve the mechanical strength and adhesion of conductive polymer films. In this work, we propose a controllable electrochemical approach for preparing ppy-silica hybrid thin films from a solution containing both pyrrole and silane monomers. It is known that pyrrole can be electropolymerised using anodic potentials, while silica can be electrodeposited under cathodic potentials. Thus, we studied the formation of ppy-silica hybrid thin films on a stainless steel surface by applying alternating potentials, i.e. cathodic followed by anodic pulses (denoted C + A) or anodic followed by cathodic pulses (denoted A + C). We show that by controlling the deposition potential and time for the cathodic and anodic pulses, the film thickness and composition can be manipulated well as analysed using profilometry and EDX. The element depth profile of the films was characterized using secondary ion mass spectroscopy (SIMS). In essence, for the C + A process, pyrrole diffuses through the cathodically electrodeposited wet silica gel layer and undergoes anodic polymerisation on the substrate, while for the A + C process, silane can be electrodeposited both on top of the anodically electrodeposited conductive ppy films as well as on the stainless steel through the pinholes in the ppy film. This offers a simple approach for tuning the structure of conductive polymer-sol-gel composite films.

Raveh M; Liu L; Mandler D

2013-07-01

385

Electrochemical co-deposition of conductive polymer-silica hybrid thin films.  

Science.gov (United States)

Conductive polymers, such as polypyrrole (ppy), have been the subject of numerous studies due to their promising applications in organic solar cells, flexible electronics, electrochromic devices, super capacitors, etc. Yet, their application is still limited as a result of poor processability. Silica has been reported to improve the mechanical strength and adhesion of conductive polymer films. In this work, we propose a controllable electrochemical approach for preparing ppy-silica hybrid thin films from a solution containing both pyrrole and silane monomers. It is known that pyrrole can be electropolymerised using anodic potentials, while silica can be electrodeposited under cathodic potentials. Thus, we studied the formation of ppy-silica hybrid thin films on a stainless steel surface by applying alternating potentials, i.e. cathodic followed by anodic pulses (denoted C + A) or anodic followed by cathodic pulses (denoted A + C). We show that by controlling the deposition potential and time for the cathodic and anodic pulses, the film thickness and composition can be manipulated well as analysed using profilometry and EDX. The element depth profile of the films was characterized using secondary ion mass spectroscopy (SIMS). In essence, for the C + A process, pyrrole diffuses through the cathodically electrodeposited wet silica gel layer and undergoes anodic polymerisation on the substrate, while for the A + C process, silane can be electrodeposited both on top of the anodically electrodeposited conductive ppy films as well as on the stainless steel through the pinholes in the ppy film. This offers a simple approach for tuning the structure of conductive polymer-sol-gel composite films. PMID:23698356

Raveh, Moran; Liu, Liang; Mandler, Daniel

2013-05-22

386

Nonequilibrium molecular dynamics methods for computing the thermal conductivity: application to amorphous polymers.  

Science.gov (United States)

We develop two nonequilibrium simulation methods which are suitable for calculation of thermal conductivity with good accuracy. These methods are based on simple algorithms, and it will be very easy to extend their range of application. In particular, there are no restrictions (from, e.g., the force field) to apply them to a variety of systems. Here, they are applied to the calculation of the thermal conductivity of amorphous polyamide-6,6 systems. We treat two models of the polymer with different degrees of freedoms constrained. The results suggest that the methods are quite efficient, and that thermal conductivity strongly depends on the number of degrees of freedom in the model. PMID:17677201

Terao, Takamichi; Lussetti, Enrico; Müller-Plathe, Florian

2007-05-25

387

Lithium ion conduction in ionic liquid-based gel polymer electrolyte  

Energy Technology Data Exchange (ETDEWEB)

The conduction mechanism of gel electrolyte system consisting of poly(ethylene oxide) branched poly(methyl methacrylate) (PEO-PMA) matrix and ionic liquid containing lithium salt has been investigated. The kinetics of ion conduction and the mobility of lithium ion are different by the kind of ionic liquid; 1-ethyl-3-methyl imidazolium bis(trifluoromethane sulfone)imide (EMITFSI) or hexyltrimethylammonium bis(trifluoromethane sulfone)imide (HTMATFSI). Lithium ion exhibits a significant contribution for ion conduction in the gel electrolyte containing HTMATFSI. In contrast, the mobility of lithium ion is not obvious in the gel electrolyte containing EMITFSI. Such difference is considered to originate from the difference in 'miscibility' of polymer component in ionic liquid. (author)

Egashira, Minato; Todo, Hirotaka; Yoshimoto, Nobuko; Morita, Masayuki [Graduate School of Science and Engineering, Yamaguchi University, Tokiwadai, Ube, Yamaguchi 755-8611 (Japan)

2008-04-01

388

Solvato-controlled doping of conducting polymers: Enhanced stability in silver-triflate doped films  

Energy Technology Data Exchange (ETDEWEB)

Stable, conductive films of poly(3-alkylthiophenes) (P3ATs) can be obtained from a single chloroform based solution containing polymer, oxidant (silver triflate), and an oxidant-coordinating ligand (pyridine). Casting of this solution, followed by evaporation of the ligand, results in an electronically conductive film which is more stable and, notably, in the case of thick films, is free of the cracking which often results from swelling of the films during the doping process. This technique, coined solvato-controlled oxidative doping, results in films possessing enhanced stability compared to those oxidized by conventional dopants such as ferric chloride. Also, these silver-containing films are much more stable than those electrochemically doped with the triflate anion. Thus, the presence of metallic silver in the doped film has a profound effect on the stability of the conducting form.

Lauritzen, M.V.; Holdcroft, S.

1998-07-01

389

Preparation of UV-crosslinked polymer electrolyte and the effect of crosslinking density on ion conductive properties  

Energy Technology Data Exchange (ETDEWEB)

UV cured polymer electrolyte were prepared from poly(ethylene glycol) ethyl ether methacrylate, poly(ethylene glycol)diacrylate, lithium salts, and propylene carbonate and ethylene carbonate were used as plasticizers. The ionic conductivity of the polymer electrolytes was increased with the amount of the plasticizers but optimum content of the plasticizers was about 55 wt% based on the weight of the polymer in the consideration of their mechanical property. The highest ionic conductivity was 1.9 X 10{sup -3} S/cm when the mol ratio of ethylene oxide repeating unit to Li{sup +} was 10. It was found that the temperature dependency of the ionic conductivity followed Vogel-Tamman-Fulcher equation, which indicates that the segmental motion of the polymer chains acts as an important role in transportation of Li ion. The ionic conductivity was varied with the kinds of lithium salts in the rage of 10{sup -3}{approx}10{sup -4} S/cm. The polymer electrolyte with lower crosslinking density had more phase-separated structure and showed higher ionic conductivity comparing with the polymer electrolyte with higher crosslinking density. From the result of linear sweep voltammetry, the polymer electrolytes were shown to be electrochemically stable up to 4.9 V.

Moon, S.I. [Korean Electrotechnology Research Institute, Changwon (Korea, Republic of); Park, I.J. [Kyungpook National University, Taegu (Korea, Republic of); Jin, B.S.; Jin, C.S. [Korea Electrotechnology Research Institute, Changwon (Korea, Republic of); Kim, W.S. [Kyungpook National University, Taegu (Korea, Republic of)

1998-05-01

390

Effect of interface on surface morphology and proton conduction of polymer electrolyte thin films.  

UK PubMed Central (United Kingdom)

To understand the relationship between surface morphology and proton conduction of polymer electrolyte thin films, perfluorinated ionomer Nafion® thin films were prepared on different substrates such as glassy carbon (GC), hydrophilic-GC (H-GC), and platinum (Pt) as models for the ionomer film within a catalyst layer. Atomic force microscopy coupled with an electrochemical (e-AFM) technique revealed that proton conduction decreased with film thickness; an abrupt decrease in proton conductance was observed when the film thickness was less than ca. 10 nm on GC substrates in addition to a significant change in surface morphology. Furthermore, thin films prepared on H-GC substrates with UV-ozone treatment exhibited higher proton conduction than those on untreated GC substrates. However, Pt substrates exhibited proton conduction comparable to that of GCs for films thicker than 20 nm; a decrease in proton conduction was observed at ?5 nm thick film but was still much higher than for carbon substrates. These results indicate that the number of active proton-conductive pathways and/or the connectivity of the proton path network changed with film thickness. The surface morphology of thinner films was significantly affected by the film/substrate interface and was fundamentally different from that of the bulk thick membrane.

Ohira A; Kuroda S; Mohamed HF; Tavernier B

2013-07-01

391

The influence of carbon nanotubes in inkjet printing of conductive polymer suspensions.  

UK PubMed Central (United Kingdom)

In this study, inkjet printing inks were formulated by combining the processability of the conductive polymer poly(3,4-ethylenedioxythiophene) (PEDOT) to the high conductivity of carbon nanotubes (CNTs). Conductive patterns were deposited on polymer films by piezoelectric inkjet printing. Several settings of printing were explored and analyzed by morphological observations and sheet resistance measurements. Performances of several CNTs were evaluated (single-walled, multi-walled and functionalized CNTs). Patterns can have sheet resistances from 10 537 to 225 Omega/sq between two families of CNTs. Functionalized CNTs with polyethylene glycol functions appeared to be the best candidates for printed electronics. This best combination allows us to obtain sheet resistances as low as 225 Omega/sq which is up to now one of the lowest resistances obtained by inkjet printing. This work also discusses the CNT network performances and emphasizes the degradation of electrical properties linked to the use of surfactants. This study represents an important step for the integration of CNTs in printed electronics applications and offers new opportunities to produce cost-effective electronics.

Denneulin A; Bras J; Blayo A; Khelifi B; Roussel-Dherbey F; Neuman C

2009-09-01

392

The influence of carbon nanotubes in inkjet printing of conductive polymer suspensions.  

Science.gov (United States)

In this study, inkjet printing inks were formulated by combining the processability of the conductive polymer poly(3,4-ethylenedioxythiophene) (PEDOT) to the high conductivity of carbon nanotubes (CNTs). Conductive patterns were deposited on polymer films by piezoelectric inkjet printing. Several settings of printing were explored and analyzed by morphological observations and sheet resistance measurements. Performances of several CNTs were evaluated (single-walled, multi-walled and functionalized CNTs). Patterns can have sheet resistances from 10 537 to 225 Omega/sq between two families of CNTs. Functionalized CNTs with polyethylene glycol functions appeared to be the best candidates for printed electronics. This best combination allows us to obtain sheet resistances as low as 225 Omega/sq which is up to now one of the lowest resistances obtained by inkjet printing. This work also discusses the CNT network performances and emphasizes the degradation of electrical properties linked to the use of surfactants. This study represents an important step for the integration of CNTs in printed electronics applications and offers new opportunities to produce cost-effective electronics. PMID:19713577

Denneulin, Aurore; Bras, Julien; Blayo, Anne; Khelifi, Bertine; Roussel-Dherbey, Francine; Neuman, Charles

2009-08-28

393

The influence of carbon nanotubes in inkjet printing of conductive polymer suspensions  

Energy Technology Data Exchange (ETDEWEB)

In this study, inkjet printing inks were formulated by combining the processability of the conductive polymer poly(3,4-ethylenedioxythiophene) (PEDOT) to the high conductivity of carbon nanotubes (CNTs). Conductive patterns were deposited on polymer films by piezoelectric inkjet printing. Several settings of printing were explored and analyzed by morphological observations and sheet resistance measurements. Performances of several CNTs were evaluated (single-walled, multi-walled and functionalized CNTs). Patterns can have sheet resistances from 10 537 to 225 {Omega}/sq between two families of CNTs. Functionalized CNTs with polyethylene glycol functions appeared to be the best candidates for printed electronics. This best combination allows us to obtain sheet resistances as low as 225 {Omega}/sq which is up to now one of the lowest resistances obtained by inkjet printing. This work also discusses the CNT network performances and emphasizes the degradation of electrical properties linked to the use of surfactants. This study represents an important step for the integration of CNTs in printed electronics applications and offers new opportunities to produce cost-effective electronics.

Denneulin, Aurore; Neuman, Charles [Polypore Europe-27, Boulevard Louise Michel, F-92230 Gennevilliers (France); Bras, Julien; Blayo, Anne; Khelifi, Bertine [Laboratory of Pulp and Paper Science and Graphic Arts (LGP2) (UMR 5518 CNRS-CTP-INPG), Grenoble Institute of Technology - INP Grenoble-PAGORA, 461 rue de la Papeterie, BP 65, F-38402 St Martin d' Heres Cedex (France); Roussel-Dherbey, Francine, E-mail: Aurore@polypore.f, E-mail: Aurore.denneulin@pagora.grenoble-inp.f, E-mail: francine.roussel-dherbey@cmtc.grenoble-inp.f [Consortium des Moyens Technologiques Communs (CMTC), Grenoble Institute of Technology (INP Grenoble), 1260 rue de la piscine, BP 75, F-38402 Saint Martin D' Heres Cedex (France)

2009-09-23

394

Effect of silver nanoparticles on the DC conductivity in chitosan-silver triflate polymer electrolyte  

International Nuclear Information System (INIS)

A solid polymer electrolyte composed of chitosan and silver triflate (AgCF3SO3) has been prepared by the solution cast technique. The formation of polymer-salt complex has been confirmed by X-ray diffraction. The DC electrical conductivity of chitosan-silver triflate electrolyte has been investigated between 303 and 423 K, using electrochemical impedance spectroscopy over the frequency range from 50 Hz to 1000 kHz. The conductivity was found to increase with increase in AgCF3SO3 concentration at room temperature. The DC conductivity obeys Arrhenius relationship up to a particular temperature and decreases at higher temperatures due to decrease in silver ions as a result of the formation of silver nanoparticles. The presence of an additional semicircular arc in the Cole-Cole plot obtained above 328 K indicates the existence of grain boundaries, which can be attributed to the silver particles. The presence of silver particles also have been proven by XRD after heating at 333, 363, and 393 K where the (1 1 1) peak of Ag is observed to increase with temperature. The silver particles were shown to be of nanosize using transmission electron microscopy (TEM).

2010-11-01

395

Application of conductive polymers, scaffolds and electrical stimulation for nerve tissue engineering.  

UK PubMed Central (United Kingdom)

Among the numerous attempts to integrate tissue engineering concepts into strategies to repair nearly all parts of the body, neuronal repair stands out. This is partially due to the complexity of the nervous anatomical system, its functioning and the inefficiency of conventional repair approaches, which are based on single components of either biomaterials or cells alone. Electrical stimulation has been shown to enhance the nerve regeneration process and this consequently makes the use of electrically conductive polymers very attractive for the construction of scaffolds for nerve tissue engineering. In this review, by taking into consideration the electrical properties of nerve cells and the effect of electrical stimulation on nerve cells, we discuss the most commonly utilized conductive polymers, polypyrrole (PPy) and polyaniline (PANI), along with their design and modifications, thus making them suitable scaffolds for nerve tissue engineering. Other electrospun, composite, conductive scaffolds, such as PANI/gelatin and PPy/poly(?-caprolactone), with or without electrical stimulation, are also discussed. Different procedures of electrical stimulation which have been used in tissue engineering, with examples on their specific applications in tissue engineering, are also discussed.

Ghasemi-Mobarakeh L; Prabhakaran MP; Morshed M; Nasr-Esfahani MH; Baharvand H; Kiani S; Al-Deyab SS; Ramakrishna S

2011-04-01

396

Conductivity and Activation Energy in Polymers Synthesized by Plasmas of Thiophene  

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish En este trabajo se estudia la síntesis por plasmas resistivos a radiofrecuencia de politiofeno, su conductividad eléctrica, energía de activación y morfología. Las continuas colisiones de partículas en el plasma inducen la polimerización del tiofeno pero también rompen algunos anillos del monómero produciendo polímeros complejos con anillos de tiofeno y segmentos de hidrocarburos alifáticos. Estas reacciones químicas multidireccionales son más marcadas en tie (more) mpos de reacción largos donde la morfología de las películas evoluciona de superficies lisas, a bajos tiempos de reacción, hasta la formación de partículas esféricas con diámetros de 300 a 1000 nm. Entre ambas morfologías, algunas burbujas se forman sobre la superficie. La conductividad intrínseca de los politiofenos sintetizados de esta manera varía en el intervalo de 10-10 a 10-8 S/m, con conductividad sensible a la humedad de los polímeros, la cual produce variaciones de hasta 5 órdenes de magnitud. La energía de activación relacionada con la conductividad intrínseca se calculó entre 0.56 y 1.41 eV, incrementándose con el tiempo de reacción. Abstract in english The electric conductivity, activation energy and morphology of polythiophene synthesized by radiofrequency resistive plasmas are studied in this work. The continuous collisions of particles in the plasma induce the polymerization of thiophene but also break some of the monomer molecules producing complex polymers with thiophene rings and aliphatic hydrocarbon segments. These multidirectional chemical reactions are more marked at longer reaction times in which the morpholo (more) gy of the polymers evolved from smooth surfaces, at low exposure time, to spherical particles with diameter in the 300-1000 nm interval. Between both morphologies, some bubbles are formed on the surface. The intrinsic conductivity of plasma polymers of thiophene synthesized in this way varied in the range of 10-10 to 10-8 S/m; however, the conductivity resulted very sensitive to the water content in the polymers, which produced variations of up to 5 magnitude orders. The activation energy of the intrinsic conductivity was between 0.56 and 1.41 eV, increasing with the reaction time.

Olayo, Ma. Guadalupe; Cruz, Guillermo J.; López, Salvador; Morales, Juan; Olayo, Roberto

2010-03-01

397

Ion conductivity of novel polyelectrolyte gels for secondary lithium-ion polymer batteries  

Energy Technology Data Exchange (ETDEWEB)

A novel polyelectrolyte gel system, promising for application in secondary polymer lithium batteries, is presented. The gel is a copolymer of N,N-dimethylacryl amide and lithium 2-acrylamido-2-methyl-1-propane sulphonate, chemically cross-linked to form a three-dimensional network. The gel was polymerised in a solvent mixture of N,N-dimethylacetamide and ethylene carbonate. The electrochemical stability of the system was examined. The effects of the monomer composition, polyelectrolyte concentration and temperature on the ionic conductivity were studied and are discussed. (author)

Travas-Sejdic, J.; Steiner, R.; Desilvestro, J.; Pickering, P. [Paciific Lithium Ltd., Manukau City, Auckland (New Zealand)

2001-07-01

398

Quantitative evaluation of quartz-micro-balance results characterizing the electrochemistry of conducting polymer films  

Energy Technology Data Exchange (ETDEWEB)

Most driver-circuits of the electrochemical quartz-microbalance (E-QMB) are sensitive to the change of the serial resistance R' of the equivalent circuit of the quartz. R' is determined by the viscoelastic properties of the contacting media of the quartz. The changes of R' during the deposition and the switching of the conducting polymer polypyrrole have been determined and the consequences for the conversion of the measured frequency-changes into mass-changes are discussed. (orig.)

Fruboese, C. (Fritz-Haber-Inst., Max-Planck-Gesellschaft, Berlin (Germany)); Doblhofer, K. (Fritz-Haber-Inst., Max-Planck-Gesellschaft, Berlin (Germany))

1993-03-22

399

Electrochemical doping processes in conducting polymers followed by in situ laser electroreflection  

Energy Technology Data Exchange (ETDEWEB)

A laser electroreflectance technique was assembled for in situ studies of electrochemical processes occurring in thin and transparent layers, involving optical transitions, on a non transparent electrode. This technique is adequate to follow variations of the population of polarons, bipolarons, [pi] or [pi][sup *] levels in conducting polymers during oxidation or reduction processes. It competes with ESR to follow the population of polarons. The population of polarons in polypyrrole films during oxidation or reduction in acetonitrile and the evolution of the i