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1

Cellulose nanocrystal: electronically conducting polymer nanocomposites for supercapacitors  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This thesis describes the use of cellulose nanocrystals for the fabrication of porous nanocomposites with electronic conducting polymers for electrochemical supercapacitor applications. The exceptional strength and negatively charged surface functionalities on cellulose nanocrystals are utilised in these nanocomposites. The negatively charged surface functionalities on cellulose nanocrystals allow their simultaneous incorporation into electropolymerised, positively charged conducting polymer ...

Liew, Soon Yee

2012-01-01

2

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

3

Nanocrystal: Conducting Polymer Solar Cells via a New Synthetic Route  

CERN Multimedia

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

4

Reversible conductance switching characteristics in a polymer-In2O3 nanocrystals junction  

Directory of Open Access Journals (Sweden)

Full Text Available A transparent polymer-based resistive switching device containing In2O3 nanocrystals (NCs is fabricated, and its nonvolatile memory characteristics are evaluated. Very clear reversible counter-clockwise bipolar-type resistive switching phenomena are observed. Stable retention is demonstrated. An Analysis of the temperature dependence of the bistable resistance states reveals additional features, not reported in previous studies, that the observed resistance switching is due to oxygen ions drift-induced redox reactions at the polymer/In2O3 NCs interface. The RESET and SET switching times (?RESET and ?SET, which are defined as pulse widths extrapolated by the steepest slopes in the transition region, are ?RESET ? 550 nsec and ?SET ? 900 nsec. The authors propose that microscopic potential modification occurring near the polymer/In2O3 NCs boundaries plays a key role in determining resistive switching properties.

Jongmin Kim

2014-06-01

5

Hybrid nanoimprinted laser based on conjugated conductive polymer and nanocrystal quantum dots.  

Science.gov (United States)

A composite of the conjugate conductive polymer poly(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene) (MEH-PPV) and CdSe/ZnS quantum dots (QDs) is utilized for nanoimprinted lasers after drop-casting onto one-dimensional omnidirectional Bragg mirrors. Strong amplified spontaneous emission is observed at the resonances of both the QDs and the polymer. Clearly resolved, low-threshold lasing was found after nanoimprinting of distributed-feedback gratings on the composite surface. Energy transfer between the polymer molecules and the QDs is demonstrated by excitation spectroscopy. PMID:20237626

Lavchiev, Ventsislav; Saeed, Ahmad; Hu, Chunguang; Dubec, Viktor; Pogany, Dionyz; Hilber, Wolfgang; Jantsch, Wolfgang

2010-03-15

6

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

Science.gov (United States)

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. PMID:23590119

Liang, Yen Nan; Yu, Kui; Yan, Qingyu; Hu, Xiao

2013-05-22

7

Nanopatterned Electrically Conductive Films of Semiconductor Nanocrystals  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We present the first semiconductor nanocrystal films of nanoscale dimensions that are electrically conductive and crack-free. These films make it possible to study the electrical properties intrinsic to the nanocrystals unimpeded by defects such as cracking and clustering that typically exist in larger-scale films. We find that the electrical conductivity of the nanoscale films is 180 times higher than that of drop-cast, microscopic films made of the same type of nanocrystal. Our technique fo...

Mentzel, Tamar; Wanger, Darcy Deborah; Ray, Nirat; Walker, Brian J.; Strasfeld, David B.; Bawendi, Moungi G.; Kastner, Marc

2012-01-01

8

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; Dittmer, Janke J.; Huynh, Wendy U.; Milliron, Delia

2014-06-17

9

Semiconductor-nanocrystal/conjugated polymer thin films  

Science.gov (United States)

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

10

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

11

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<5 nm) surface coated with polystyrene of varying molecular weight. The polymer is tethered to the nanoparticles via a terminal thiol to provide strong attachment. Our data show that at full coverage the polymer assumes a brush conformation and is 44% longer than the unbound polymer in solution. The brush conformation is confirmed by comparison with models used to describe polymer brushes at flat interfaces. From this work, we suggest an empirical formula which predicts the hydrodynamic diameter of polymer coated nanoparticles based on the size of the nanoparticle core and the size of the randomly coiled unbound polymer in solution

2007-11-28

12

Non-volatile memory device using a polymer modified nanocrystal  

Energy Technology Data Exchange (ETDEWEB)

Thin-film planar structures using AgCl nanocrystals embedded in a polymer blend; exhibit reliable and reproducible switching between different non-volatile conductance states. It is shown that resistive switching in these systems cannot be related with migration diffusion or aggregation of metals to form metallic filaments. This is supported by temperature-dependent measurement showing that the current in the high conductance state is thermal activated (0.6 eV).

Kiazadeh, A., E-mail: asal.kiazadeh@gmail.com [Center of Electronics Optoelectronics and Telecommunications (CEOT), Universidade do Algarve, Campus de Gambelas, 8000-139 Faro (Portugal); Gomes, H.L., E-mail: hgomes@ualg.pt [Center of Electronics Optoelectronics and Telecommunications (CEOT), Universidade do Algarve, Campus de Gambelas, 8000-139 Faro (Portugal); Rosa da Costa, A.M.; Moreira, J.A. [Centro de Investigacao em Quimica do Algarve, Universidade do Algarve, Campus de Gambelas, 8000-139 Faro (Portugal); Leeuw, D.M. de [Philips Research Laboratories, High Tech Campus 4 WAG 11, 5656 AE Eindhoven (Netherlands); Meskers, S.C.J. [Molecular Materials and Nanosystems, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands)

2011-11-25

13

Electrically Conductive Polymer Compositions.  

Science.gov (United States)

A conductive polymer composite system is made by dissolving an electron donating polymer and a simple or complex N-methylphenazinium TCNQ salt in a mutual solvent and casting a film of the resulting solution on a suitable substrate.

O. K. Kim

1983-01-01

14

Hybrid polymer-nanocrystal materials for photovoltaic applications.  

Science.gov (United States)

Hybrid polymer-nanocrystal photovoltaic (PV) cells have received much attention during the past decade as promising low-cost solar energy harvesting devices, and showed significant progress with power conversion efficiency reaching 5% recently. This review starts from the introduction of hybrid materials to their application in electronic devices, with particular focus on bulk-heterojunction hybrid polymer-nanocrystal PV devices. The synthesis, surface chemistry, and electronic properties of colloidal inorganic nanocrystals are described. The recent development of hybrid PV devices will be discussed from the perspective of tailoring both inorganic nanocrystals and conjugated polymers, controlling polymer-nanocrystal hybrid morphology, engineering polymer-nanocrystal interface, and optimizing device architecture. Finally, future directions for further advancing hybrid PV technology to potential commercialization are also discussed. PMID:22461231

Zhou, Renjia; Xue, Jiangeng

2012-07-16

15

Thermally conductive polymers  

Science.gov (United States)

A thermally conductive polymer is provided having physical and chemical properties suited to use as a medium for potting electrical components. The polymer is prepared from hydroquinone, phenol, and formaldehyde, by conventional procedures employed for the preparation of phenol-formaldehyde resins. While the proportions of the monomers can be varied, a preferred polymer is formed from the monomers in a 1:1:2.4 molar or ratio of hydroquinone:phenol:formaldehyde.

Byrd, N. R.; Jenkins, R. K.; Lister, J. L. (inventors)

1971-01-01

16

'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. (c) 2005 Elsevier Ltd. All rights reserved.

Winther-Jensen, Bjørn; Chen, Jun

2005-01-01

17

Polymer ligand exchange to control stabilization and compatibilization of nanocrystals.  

Science.gov (United States)

We demonstrate polymer ligand exchange to be an efficient method to control steric stabilization and compatibilization of nanocrystals. A rational design of polymer binding groups and ligand exchange conditions allows to attach polymer brushes with grafting densities >1 nm(-2) to inorganic nanocrystals for nearly any nanocrystal/polymer combination using only a few types of binding groups. We demonstrate the potential of the method as an alternative to established grafting-from and grafting-to routes in considerably increasing the stabilization of inorganic nanocrystals in solution, to prepare completely miscible polymer nanocomposites with a controllable distance between nanoparticles, and to induce and control aggregation into percolation networks in polymeric matrices for a variety of different nanocrystal/polymer combinations. A dense attachment of very short polymer ligands is possible enabling to prepare ordered nanoparticle monolayers with a distance or pitch of only 7.2 nm, corresponding to a potential magnetic storage density of 12.4 Tb/in(2). Not only end-functionalized homopolymers, but also commercially available copolymers with functional comonomers can be used for stable ligand exchange, demonstrating the versatility and broad potential of the method. PMID:24870392

Ehlert, Sascha; Taheri, Sara Mehdizadeh; Pirner, Daniela; Drechsler, Markus; Schmidt, Hans-Werner; Förster, Stephan

2014-06-24

18

Sodium conducting polymer electrolytes  

Energy Technology Data Exchange (ETDEWEB)

This section deals with the aspects of ionic conduction in general as well as specific experimental results obtained for sodium systems. The conductivity as a function of temperature and oxygen/metal ratio are given for the systems NaI, NaCF/sub 3/SO/sub 3/ and NaClO/sub 4/ plus polyethylene oxide. Attempts have been made to produce mixed phase solid electrolytes analogous to the lithium systems that have worked well. These consist of mixtures of polymer and a solid electrolyte. The addition of both nasicon and sodium beta alumina unexpectedly decreases the ionic conductivity in contrast to the lithium systems. Addition of the nonconducting silica AEROSIL in order to increase the internal surface area has the effect of retarding the phase transition at 60 deg. C, but does not enhance the conductivity. (author) 23 refs.

Skaarup, S.; West, K. (eds.)

1989-04-01

19

Electrically Conductive Polymer Concrete Overlays.  

Science.gov (United States)

The development of a built-up, electrically conductive polymer concrete overlay and a premixed, electrically conductive polymer concrete mortar for use on bridge decks and other concrete members, in conjunction with cathodic protection systems, is reporte...

R. P. Webster J. J. Fontana W. Reams

1985-01-01

20

Multifunctional Composites Obtained by Incorporating Nanocrystals into Decorated PVK Polymers  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 solu...

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

2007-01-01

 
 
 
 
21

Polymer Conductivity through Particle Connectivity  

Science.gov (United States)

To promote solution processability of conductive polymers, polymer acids, instead of small-molecule acids, are frequently used as dopants. Generally, the conductive polymer is synthesized in the presence of the polymer acid; sub-micron size particles that are electrostatically stabilized result during polymerization. We discovered that the molecular characteristics of the polymer acid have great implications on the structure of these conductive polymer particles. Templating the synthesis of the conductive polymer with a higher molecular weight polymer acid results in larger particles, and templating with a polymer acid having a larger molecular weight distribution results in a large size distribution in the particles. Because conduction in such conductive polymers is governed by how these particles pack, we show that the macroscopic conductivity of these films is dictated by a single parameter, i.e., the particle density, that is reducible from the various molecular characteristics of the polymer acid we explored. In the specific case of polyaniline that is doped with poly(2-acrylamido-2-methyl-1-propane sulfonic acid), the particles are structurally and chemically inhomogeneous. The conductive portions of the polymer preferentially segregate to the particle surface. Conduction in these materials are therefore mediated by the particle surface and conductivity thus scales superlinearly with particle surface area per unit film volume.

Loo, Yueh-Lin

2009-03-01

22

Synthesis of Doped Semiconductor Nanocrystals and Conductive Coatings  

Science.gov (United States)

Semiconductor nanocrystals are an intriguing class of materials because of their size-tunable properties. This makes them promising for future optoelectronic devices such as solar cells and light emitting diodes. Realization of these devices, however, requires precise control of the flow of electricity through the particles. In bulk semiconductors, this is achieved by using materials with few unintentional defects, then intentionally adding particular defects or dopants to alter the semiconductor's electronic properties. In contrast, the addition of electrically active dopants has scarcely been demonstrated in semiconductor nanocrystals, and charge transport is hindered by the barrier of electron hopping between particles. The goal of this thesis, therefore, is to discover new methods to control charge transport in nanocrystals. It divides into three major thrusts: 1) the investigation of the doping process in semiconductor nanocrystals, 2) the invention of new synthetic methods to incorporate electrically active dopants into semiconductor nanocrystals, and 3) the invention of a new nanocrystal surface coating that aids processing of nanocrystals into devices but can be removed to enhance charge transport between particles. The first objective is achieved by the comparison of four different precursors that have been used to dope Mn into nanocrystals. Experiments show that dimethylmanganese incorporates efficiently into ZnSe nanocrystals while other precursors are less efficient and sometimes lower the quality of the nanocrystals produced. The second goal is met by the application of a core-shell synthetic strategy to the incorporation of non-isovalent impurities (Al and In) into CdSe nanocrystals. By separating the three steps of nucleation, dopant binding, and growth, each step can be optimized so that doping is achieved and high quality particles are produced. Detailed characterization shows dopant incorporation and local environment, while transistor measurements reveal that the nanocrystal Fermi level rises with increasing Al content. The third thrust is achieved by the use of primary dithiocarbamates as ligands to stabilize CdSe, and PbSe / CdSe core/shell nanoparticles. Primary dithiocarbamates bind well to metals but include a weak chemical bond that can be broken with gentle heating. This enables us to bind them to nanoparticles, process the particles into devices, then remove the ligand via gentle heating. Characterization of the ligand-particle interactions show excellent ligand binding to the particle surface and easy ligand removal with heating. After ligand removal, the inter-particle spacing shrinks. Transistor measurements reveal that this reduces the barrier to interparticle electron transport, enhancing the conductivity of the film.

Wills, Andrew Wilke

23

Electrically Conductive Polymer Concrete Coatings.  

Science.gov (United States)

The corrosion of reinforcing steel embedded in concrete causes cracks and delamination in the concrete. The application of impressed current cathodic protection utilizing electrically conductive polymer concrete to distribute the current across concrete b...

J. J. Fontana

1985-01-01

24

Conducting Polymer 3D Microelectrodes  

Directory of Open Access Journals (Sweden)

Full Text Available 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.

Jenny Emnéus

2010-12-01

25

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.

Bai Yang

2007-10-01

26

Electrospun porous conductive polymer membranes  

Science.gov (United States)

In this work, two methodologies were used in fabricating conductive electrospun polymer fibers with nano features. We first investigated the addition of multiwall carbon nanotubes (MWCNT) as conductive fillers at concentrations ranging from 1 to 10% into a polystyrene (PS) matrix. Electrospinning conditions were tailored to produce fibers with minimal beads. Next, we investigated the effects of coating electrospun fibers with nano structured conductive polymer. Oxidant (FeCl3) fibers were electrospun in PS and then exposed to a pyrrole (Py) monomer in a vacuum chamber. As a result, polypyrrole (PPy) was coated on the fibers creating conductive pathways. In both methods, the electrospun conductive fibers were characterized in terms of their morphologies, thermal stability and electrical conductivity. Strong correlations were found among PPy coating nanostructures, oxidant concentration and polymerization time. Electrospun fibrous membranes with conductive polymer coating exhibit much higher electrical conductivities compare to fibers with conductive fillers. Highest conductivity achieved was 9.5E-4 S/cm with 40% FeCl3/PS fibers polymerized with Py for 140 min.

Wang, Jingwen; Naguib, Hani E.; Bazylak, Aimy

2012-03-01

27

Electrically conductive polymer concrete coatings  

Energy Technology Data Exchange (ETDEWEB)

The corrosion of reinforcing steel embedded in concrete causes cracks and delamination in the concrete. The application of impressed current cathodic protection utilizing electrically conductive polymer concrete to distribute the current across concrete bridge deck surfaces is gradually becoming a standard practice in the highway industry. In order to protect the bridge substructures, a sprayable electrically conductive polymer concrete coating is being developed. This thin coating has a very low resistivity and can distribute the cathodic protection current across the concrete surfaces that are to be protected.

Fontana, J.J.

1985-10-01

28

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

Science.gov (United States)

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. PMID:19809115

Stavrinadis, Alexandros; Xu, Sen; Warner, Jamie H; Hutchison, John L; Smith, Jason M; Watt, Andrew A R

2009-11-01

29

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

Energy Technology Data Exchange (ETDEWEB)

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.

Stavrinadis, Alexandros; Xu Sen; Warner, Jamie H; Hutchison, John L; Smith, Jason M; Watt, Andrew A R, E-mail: andrew.watt@materials.ox.ac.u [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom)

2009-11-04

30

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

31

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

32

Electrophoretic deposition of CdSe nanocrystal films onto dielectric polymer thin films  

International Nuclear Information System (INIS)

The electrophoretic deposition of cadmium selenide (CdSe) nanocrystal films from a stable hexane suspension onto a dielectric polymer film is reported. The electrodes were prepared by spin casting a ? 30 nm thick smooth, defect-free, polystyrene film on silicon substrates. Scanning electron microscopy and atomic force microscopy showed that the CdSe films deposited atop polystyrene possessed morphology comparable to CdSe films deposited on the bare silicon electrodes. Factors affecting deposition, such as nanocrystal charging in suspension and wetting of electrode surfaces, are reviewed. This approach to preparing nanocrystal films onto homogeneous dielectric layers will facilitate the fabrication of novel polymer-nanocrystal composites

2009-02-27

33

Microwave properties of conductive polymers  

Energy Technology Data Exchange (ETDEWEB)

Conductive polymers are a new class of microwave absorbing materials which show a number of advantages over traditional granular materials. Polypyrrole, Polyaniline, and Polyalkylthiophenes can be applied in specific fields where the conductive inclusion is directly integrated in the matrix or on the substrate (honeycomb, textile) during synthesis, instead of being mechanically dispersed as in the case of extrinsic conductive materials. This method can be used to produce materials with specific properties, whose performances are equivalent to those of magnetic materials but with lower surface mass. The properties of these materials can be easily modified by chemical means and by tailoring the structural properties. We show that dielectric properties strongly depend on the microstructure of conductive polymer. For that purpose, the influence of the molecular weight, density of defects, size of the alkyl chain on the substituted monomer and nature of counter anion have been explored. Theoretical models using physicochemical properties of polymer have been developed in order to calculate the frequency dependence of ({epsilon}`,{epsilon}``) with for a chain of Polyaniline. (orig.)

Olmedo, L. [CEA/Centre d`Etudes du Ripault, 37 - Monts (France); Hourquebie, P. [CEA/Centre d`Etudes du Ripault, 37 - Monts (France); Jousse, F. [CEA/Centre d`Etudes du Ripault, 37 - Monts (France)

1995-03-01

34

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

35

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

36

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, J.J.; Elling, D.; Reams, W.

1990-03-13

37

Electrically conductive polymer concrete coatings  

Energy Technology Data Exchange (ETDEWEB)

A sprayable electrically conductive polymer concrete coating for vertical and 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 resin 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. 4 tabs.

Fontana, J.J.; Elling, D.; Reams, W.

1988-05-26

38

Electrically conductive polymer concrete coatings  

Science.gov (United States)

A sprayable electrically conductive polymer concrete coating for vertical and overhead applications is described. The coating is permeable yet has low electrical resistivity (concrete substrates, and good weatherability. A preferred formulation contains about 60 wt% calcined coke breeze, 40 wt% vinyl ester resin 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. 4 tabs.

Fontana, J.J.; Elling, D.; Reams, W.

1988-05-26

39

Charge transport in conducting polymers  

International Nuclear Information System (INIS)

Polymers with metal-like electrical conductivity are presented as novel materials. After a short discussion of the present situation of technical applications experimental data on the electrical conductivity and its temperature and frequency dependence are reviewed. These data are discussed within the framework of a model involving fluctuation-induced tunneling between marcroscopic inhomogeneities and energy dependent hopping of charge carriers between localized states on a microscopic level. Pulsed photoconductivity measurements indicate that also in photoconductivity a hopping mechanism is dominant and solitary wave motion of conjugational defects escapes observation. (orig.)

1984-01-01

40

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

 
 
 
 
41

Optical properties of conjugated polymer-ZnSe nanocrystal nanocomposites  

International Nuclear Information System (INIS)

Nanocomposites of poly[(2-methoxy,5-octoxy)1,4-phenylenevinylene]-zinc selenide (MOPPV-ZnSe) are synthesized by mixing the polymerization of 1,4-bis (chloromethyl)-2-methoxy-5-octoxy-benzene in the presence of ZnSe quantum dots. The resulting MOPPV-ZnSe nanocomposites possess a well-defined interfacial contact, thus significantly promoting the dispersion of ZnSe within the MOPPV matrix and facilitating the electronic interaction between these two components. Raman and UV–visible absorption spectra are influenced by the incorporation of ZnSe nanocrystals. High-resolution transmission electron microscopic and tapping-mode atomic force microscopic results show clearly the evidence for phase-segregated networks of ZnSe nanocrystals, which provide a large area of interface for charge separation to occur. Steady-state spectra of MOPPV-ZnSe nanocomposites are markedly quenched by the introduction of intimate polymer/ZnSe junctions. Time-resolved photoluminescence measurements show that the lifetime decays quickly, which further confirms the occurrence of charge transfer in MOPPV-ZnSe nanocomposites. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

2010-01-01

42

Alkyl Passivation and Amphiphilic Polymer Coating of Silicon Nanocrystals for Diagnostic Imaging  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We show a method to produce biocompatible polymer-coated silicon (Si) nanocrystals for medical imaging. Silica-embedded Si nanocrystals are formed by HSQ thermolysis. The nanocrystals are then liberated from the oxide and terminated with Si-H bonds by HF etching, followed by alkyl monolayer passivation by thermal hydrosilylation. The Si nanocrystals have an average diameter of 2.1 ± 0.6 nm and photoluminesce (PL) with a peak emission wavelength of 650 nm, which lies within the transmission w...

Hessel, Colin M.; Rasch, Michael R.; Hueso, Jose L.; Goodfellow, Brian W.; Akhavan, Vahid A.; Puvanakrishnan, Priyaveena; Tunnell, James W.; Korgel, Brian A.

2010-01-01

43

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

44

Preparation of optical media from compositions of dye nanocrystals in polymer matrices  

Energy Technology Data Exchange (ETDEWEB)

It is shown that nanocrystals of organic dyes can be grown in solutions by known methods of colloidal chemistry and used for preparation of solid compositions consisting of dye nanocrystals in a polymer binder at comparable concentrations of components. These optically uniform compositions represent novel optical media based on organic compounds with optical and semiconducting properties determined by the dye in a crystalline state in conjunction with mechanical and technological characteristics inherent in a polymer. 9 refs., 4 figs.

Akimov, I.A.; Denisyuk, I.Yu.; Meshkov, A.M. [Vavilov State Optical Institute, St. Petersburg (Russian Federation)

1994-12-01

45

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

46

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

47

Modeling PVDF actuators with conducting polymer electrodes  

Science.gov (United States)

Piezoelectric polymer sheets are presently supplied with metallic electrodes that have thickness comparable to the polymer sheet, so the electrode stiffness considerably degrades the performance of actuators make of such sheets. Conducting polymers, such as PEDOT/PSS, may be a good substitute for metal as an electroding material given the high flexibility of polymers. The lower conductivity of polymers, though, forces consideration of the voltage distribution in the electrodes, which will not be uniform due to amplitude decay and phase lag. We have developed a simple analytical solution for the voltage distribution, and have found an excellent agreement with experimental measurements from piezoelectric bimorphs that have been constructed in our laboratory.

Lediaev, Laura M.; Schmidt, V. H.

2005-05-01

48

Conducting polymer composites of polypyrrole and polyimide  

Energy Technology Data Exchange (ETDEWEB)

A conducting composite of polypyrrole with a polyimide as the insulating matrix polymer was prepared via electrochemical methods. The characterization of the composite was done by FTIR, SEM and TGA studies. Conductivity and solubility studies together with spectroscopic methods reveal that a chemical interaction between the two polymers exists. (orig.)

Selampinar, F. [Middle East Technical Univ., Ankara (Turkey). Dept. of Chemistry; Akbulut, U. [Middle East Technical Univ., Ankara (Turkey). Dept. of Chemistry; Toppare, L. [Department of Chemistry, Bilkent University, 06533 Ankara (Turkey)

1997-01-01

49

Mixed ionic and electronic conductivity in polymers  

Energy Technology Data Exchange (ETDEWEB)

In the past year, we have made progress in the theory of mixed ionic and electronic conductivity in polymers. On the experimental side, we have prepared polypyrroles with pendant polyethers and studied their conductivity in the reduced state. Theoretical progress was made in the application of Monte Carlo methods to ion motion in polymers.

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

1992-07-01

50

ELECTRICALLY CONDUCTIVE POLYMER-POLYMER COMPOSITES  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Conductive composites have been prepared by polymerization of acelene in polyethylene films followed by iodine doping. The attainment of high conductivity (5-10 S/cm) at low (CH)x concentrations (?3 wt%) is explained with a simple percolation model.

Galvin, M.; Wnek, G.

1983-01-01

51

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

52

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. 2 figs.

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

1992-04-28

53

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

54

Conductive polymer/superconductor bilayer structures  

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 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, conact resistance, atomic force microscopy and scanning electron microscopy measurements are utilized to explore the polymer/superconductor interactions

1994-08-21

55

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 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 modific...

Alain Dufresne

2010-01-01

56

Gyroid nanoporous scaffold for conductive polymers  

DEFF Research Database (Denmark)

Conductive nanoporous polymers with interconnected large surface area have been prepared by depositing polypyrrole onto nanocavity walls of nanoporous 1,2-polybutadiene films with gyroid morphology. Vapor phase polymerization of pyrrole was used to generate ultrathin films and prevent pore blocking. The resulting nanoporous polymers exhibited a promising electroactivity.

Guo, Fengxiao; Schulte, Lars

2011-01-01

57

Application of conducting polymers to electroanalysis  

Energy Technology Data Exchange (ETDEWEB)

Conducting polymers can be used as sensitive layers in chemical microsensors leading to new applications of theses devices. They offer the potential for developing material properties that are critical to the sensor sensitivity, selectivity and fabrication. The advantages and limitations of the use of thin polymer layers in electrochemical sensors are discussed.

Josowicz, M.A.

1994-04-01

58

Moldable Electrically Conductive Polymer Compositions.  

Science.gov (United States)

Accordingly, it is an object of this invention to obtain high electrical conductivity in a polymeric composition. Another object is to provide a bulky, moldable polymeric composition that conducts electricity. Another object is to provide a polymeric comp...

O. K. Kim

1985-01-01

59

Sprayable Electrically Conductive Polymer Concrete Coatings.  

Science.gov (United States)

A sprayable electrically conductive polymer concrete coating for vertical and overhead applications has been developed. The technology, in conjunction with impressed current cathodic protection, can be used to prevent corrosion of the embedded reinforcing...

J. J. Fontana W. Reams D. Elling

1985-01-01

60

Conducting polymers in chemical sensors and arrays.  

Science.gov (United States)

The review covers main applications of conducting polymers in chemical sensors and biosensors. The first part is focused on intrinsic and induced receptor properties of conducting polymers, such as pH sensitivity, sensitivity to inorganic ions and organic molecules as well as sensitivity to gases. Induced receptor properties can be also formed by molecularly imprinted polymerization or by immobilization of biological receptors. Immobilization strategies are reviewed in the second part. The third part is focused on applications of conducting polymers as transducers and includes usual optical (fluorescence, SPR, etc.) and electrical (conductometric, amperometric, potentiometric, etc.) transducing techniques as well as organic chemosensitive semiconductor devices. An assembly of stable sensing structures requires strong binding of conducting polymers to solid supports. These aspects are discussed in the next part. Finally, an application of combinatorial synthesis and high-throughput analysis to the development and optimization of sensing materials is described. PMID:18405677

Lange, Ulrich; Roznyatovskaya, Nataliya V; Mirsky, Vladimir M

2008-04-28

 
 
 
 
61

A new approach to the synthesis of conjugated polymer-nanocrystal composites for heterojunction optoelectronics.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We report a simple one pot process for the preparation of lead sulfide (PbS) nanocrystals in the conjugated polymer poly (2-methoxy-5-(2'ethyl-hexyloxy)-p-phenylene vinylene)(MEH-PPV), and we demonstrate electronic coupling between the two components.

Watt, A.; Thomsen, E.; Meredith, P.; Rubinsztein-dunlop, H.

2004-01-01

62

Efficient heterojunction photovoltaic cell utilizing nanocomposites of lead sulfide nanocrystals and a low-bandgap polymer  

Energy Technology Data Exchange (ETDEWEB)

A facile approach to make an efficient hybrid bulk heterojunction photovoltaic device with lead sulfide nanocrystals and a low-bandgap polymer is demonstarted, resulting in a power conversion efficiency of about 2-3%. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Seo, Jangwon; Cho, Min Ju; Prasad, Paras N. [Institute for Lasers, Photonics and Biophotonics, Department of Chemistry, State University of New York, Buffalo, New York, 14260 (United States); Lee, Dongho; Cartwright, A.N. [Department of Electrical Engineering, State University of New York, Buffalo, New York, 14260 (United States)

2011-09-08

63

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

2010-06-01

64

Extrusion of Polysaccharide Nanocrystal Reinforced Polymer Nanocomposites through Compatibilization with Poly(ethylene oxide).  

Science.gov (United States)

Polysaccharide nanocrystals with a rodlike shape but with different dimensions and specific surface area were prepared from cotton and capim dourado cellulose, and with a plateletlike morphology from waxy maize starch granules. The rheological behavior of aqueous solutions of poly(ethylene oxide) (PEO) with different molecular weights when adding these nanoparticles was investigated evidencing specific interactions between PEO chains and nanocrystals. Because PEO also bears hydrophobic moieties, it was employed as a compatibilizing agent for the melt processing of polymer nanocomposites. The freeze-dried mixtures were used to prepare nanocomposite materials with a low density polyethylene matrix by extrusion. The thermal and mechanical behavior of ensuing nanocomposites was studied. PMID:24840363

Pereda, Mariana; Kissi, Nadia El; Dufresne, Alain

2014-06-25

65

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

66

Picosecond transients in conducting polymers.  

Science.gov (United States)

Picosecond(ps) time-resolved photomodulation(PM) spectra in several conjugated polymers - PTV,s(CH)_x,DOOPPV,P3BT,PPA and an oligomer - ?6T have been extended to include the IR spectral range of 0.65eV to 0.86eV.Thus we have measured the ps PM spectra from 0.65 eV to 2.2eV upto 3 ns.The spectra and the relaxation dynamics in the visible and NIR range (2.2-1.25eV) were obtained with a synchronously pumped dye laser system, and in the IR range(0.8eV) - with a color center laser system. The time resolution of the PM transients was from 5 ps to 30 ps depending on the probe wavelength.The maximum PM value (?T/T) was less than 0.1% (the small signal limit).We have also measured time-resolved photoluminescence (PL) in the luminescent materials (?6T,DOOPPV,P3BT) up to 2 ns with 20ps resolution. Using the extended PM transient spectra, we could separate several types of photoexcitations, based upon their distinguished spectrum,dynamics,and similarity with the PL transient. A new model is proposed to describe the various photoexcitations.

Frolov, S. V.; Gellermann, W.; Vardeny, Z. V.

1996-03-01

67

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 imaginary conductivities of optically injected carriers in the nanocrystals to report on the degree of quantum confinement. For the smaller CdTe nanocrystals (3 nm < radius < 5 nm), the complex tera...

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

2012-01-01

68

Increasing the conductivity of crystalline polymer electrolytes  

Science.gov (United States)

Polymer electrolytes consist of salts dissolved in polymers (for example, polyethylene oxide, PEO), and represent a unique class of solid coordination compounds. They have potential applications in a diverse range of all-solid-state devices, such as rechargeable lithium batteries, flexible electrochromic displays and smart windows. For 30 years, attention was focused on amorphous polymer electrolytes in the belief that crystalline polymer:salt complexes were insulators. This view has been overturned recently by demonstrating ionic conductivity in the crystalline complexes PEO6:LiXF6 (X = P, As, Sb); however, the conductivities were relatively low. Here we demonstrate an increase of 1.5 orders of magnitude in the conductivity of these materials by replacing a small proportion of the XF6- anions in the crystal structure with isovalent N(SO2CF3)2- ions. We suggest that the larger and more irregularly shaped anions disrupt the potential around the Li+ ions, thus enhancing the ionic conductivity in a manner somewhat analogous to the AgBr1-xIx ionic conductors. The demonstration that doping strategies can enhance the conductivity of crystalline polymer electrolytes represents a significant advance towards the technological exploitation of such materials.

Christie, Alasdair M.; Lilley, Scott J.; Staunton, Edward; Andreev, Yuri G.; Bruce, Peter G.

2005-01-01

69

Integration of conducting polymer network in non-conductive polymer substrates  

DEFF Research Database (Denmark)

Anew method for integration ofconjugated, inherently conducting polymers into non-conductive polymer substrates has been developed. Alayer of the conducting polymer is polymerised by chemical oxidation, e.g. using Fe(ID) p-toluene sulfonate (ferri tosylate) followed by washing with a solvent which simultaneously removes residual and spent oxidant and at the same time dissolves the top layer of the polymer substrate. This results in an integration of the conducting polymer into the surface layers of the polymer substrate. Several combinations of conducting polymers and substrates have been tested, with particular focus on poly(3,4-ethylenedioxythiophene) (PEDOT) on PMMA substrates. The structural, electrical and mechanical properties of this system has been characterised by atomic force microscopy, conductance measurements, and tribological tests. Furthermore, measurement ofconductivity and optical absorption during sequential reactive ion etching has allowed for analysis of the PEDOT distribution within the surface layer of thePMMA substrate. The surface resistance ofthe conducting polymer layer remains low while the surface layer at the same time adapts some of the mechanical properties of the substrate, resulting in a highly conducting surface with very good wear resistance.

Hansen, Thomas Steen; West, Keld

2006-01-01

70

Ion bombardment effects in conducting polymers  

Energy Technology Data Exchange (ETDEWEB)

The modification of properties of conducting polymers by ion bombardment offers interesting possibilities for their application in the field of microelectronics and electrochemistry. Therefore foils of intrinsically conducting polymers (polypyrrole and polythiophene) were modified by noble gas ion implantation. By ion bombardment the resistivity can be increased by several orders of magnitude. This effect depends on the species, energy and ion fluence. Cyclovoltammetric experiments show the same electrochemical features for the modified foils as the untreated polymers, but the observed currents are smaller by two orders of magnitude. The conductivity of the virgin foil ([sigma]=100 S/cm) is sufficient for galvanic metal deposition. The bombardment induced change of resistivity causes an inhibition of electrochemical deposition. By using masks lateral structures in the range of several [mu]m can be produced. During implantation the black colour of the untreated foil changes to brown depending on the implanted dose. The associated changes of the chemical structures, investigated by XPS, are discussed. ((orig.))

Schiestel, S. (Institut fuer Physikalische Chemie, Im Neuenheimer Feld 500, 69120 Heidelberg (Germany)); Ensinger, W. (Institut fuer Physikalische Chemie, Im Neuenheimer Feld 500, 69120 Heidelberg (Germany)); Wolf, G.K. (Institut fuer Physikalische Chemie, Im Neuenheimer Feld 500, 69120 Heidelberg (Germany))

1994-06-01

71

Ion bombardment effects in conducting polymers  

International Nuclear Information System (INIS)

The modification of properties of conducting polymers by ion bombardment offers interesting possibilities for their application in the field of microelectronics and electrochemistry. Therefore foils of intrinsically conducting polymers (polypyrrole and polythiophene) were modified by noble gas ion implantation. By ion bombardment the resistivity can be increased by several orders of magnitude. This effect depends on the species, energy and ion fluence. Cyclovoltammetric experiments show the same electrochemical features for the modified foils as the untreated polymers, but the observed currents are smaller by two orders of magnitude. The conductivity of the virgin foil (?=100 S/cm) is sufficient for galvanic metal deposition. The bombardment induced change of resistivity causes an inhibition of electrochemical deposition. By using masks lateral structures in the range of several ?m can be produced. During implantation the black colour of the untreated foil changes to brown depending on the implanted dose. The associated changes of the chemical structures, investigated by XPS, are discussed. ((orig.))

1994-06-01

72

Enhanced luminescence in metal/ (conducting polymer) nanocomposites  

International Nuclear Information System (INIS)

Full text: We will discuss the ELINOR effect, the Enhanced Luminescence of INorganic and ORganic origin, which we recently identified in different (noble metal)/(conducting polymer) nanocomposites. The intense fluorescence of these composites can be pinned down to a synergic interaction between the plasmonic response of the nanostructured metallic aggregate and the electronic relaxation offered by the conducting polymer chains. We have shown that by careful control of the preparation conditions we can tune both the intensity and the wavelength of the emission maximum. We will discuss possible applications of these nanocomposites as molecular biomarkers (where we exploit the electrical affinity between conducting polymer chains and DNA molecules) and in the increase of efficiency of photovoltaic devices and solid state displays. Preliminary results of the ELINOR effect as a tool for rapid diagnosis of viral diseases and genetic polymorphisms will be also presented

2008-12-06

73

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

74

Structural characterization of conducting polymer  

International Nuclear Information System (INIS)

Polarized extended X-ray absorption fine structure (EXAFS) and X-ray absorption near edge structure (XANES) of stretch-oriented polyacetylene doped with bromine have been measured for (CHBry)x (0.004 y)x in the lightly doped region (0.01 0.1). The absence of bromine-bromine bonds in the very lightly doped region (y < 0.01) suggests that bromines might exist as ions. Even in this region, a part of the doped bromines are covalently bonded with polyacetylene. A simple structural model assuming the existence of polybromine ions and covalently bonded bromines is proposed on the basis of the dopant-concentration dependence of polarized EXAFS and XANES. This model is consistent with the bromine-concentration dependence on the electrical conductivity. (author)

1986-01-01

75

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

76

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

77

Measurement of thermal conductivity of PbTe nanocrystal coated glass fibers by the 3? method.  

Science.gov (United States)

Fiber-based thermoelectric materials can conform to curved surfaces to form energy harvesting devices for waste heat recovery. Here we investigate the thermal conductivity in the axial direction of glass fibers coated with lead telluride (PbTe) nanocrystals using the self-heated 3? method particularly at low frequency. While prior 3? measurements on wire-like structures have only been demonstrated for high thermal conductivity materials, the present work demonstrates the suitability of the 3? method for PbTe nanocrystal coated glass fibers where the low thermal conductivity and high aspect ratio result in a significant thermal radiation effect. We simulate the experiment using a finite-difference method that corrects the thermal radiation effect and extract the thermal conductivity of glass fibers coated by PbTe nanocrystals. The simulation method for radiation correction is shown to be generally much more accurate than analytical methods. We explore the effect of nanocrystal volume fraction on thermal conductivity and obtain results in the range of 0.50-0.93 W/mK near room temperature. PMID:24147725

Finefrock, Scott W; Wang, Yan; Ferguson, John B; Ward, James V; Fang, Haiyu; Pfluger, Jonathan E; Dudis, Douglas S; Ruan, Xiulin; Wu, Yue

2013-11-13

78

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

79

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.

Jordi Puiggalí

2013-09-01

80

CONDUCTING SN POLYMERS WITH INTEGRATED ORGANIC GROUPS  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Polymers consisting of alternating sulfur nitrogen moieties and bifunctional heterocyclic groups are prepared via Si - N bond cleavage. All compounds are obtained in good yields as highly coloured or black materials which are insoluble in common organic solvents. The pristine materials show conductivities of approximately 5.10-16 - 5.10-5 Ohm-1 cm-1. In most cases higher conductivities can be achieved by doping the samples with acceptors, e.g. iodine.

Wolmersha?user, G.; Jotter, R.; Wilhelm, T.

1983-01-01

 
 
 
 
81

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

Science.gov (United States)

We demonstrate light-induced formation of semiconductor quantum dots in TOPAS® 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.

Athanassiou, Athanassia; Cingolani, Roberto; Tsiranidou, Elsa; Fotakis, Costas; Laera, Anna Maria; Piscopiello, Emanuela; Tapfer, Leander

2007-10-01

82

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

83

Physical theory of excitons in conducting polymers.  

Science.gov (United States)

In this tutorial review, we cover the solid state physics approach to electronic and optical properties of conducting polymers. We attempt to bring together languages and advantages of the solid state theory for polymers and of the quantum chemistry for monomers. We consider polymers as generic one-dimensional semiconductors with features of strongly correlated electronic systems. Our model combines the long range electron-hole Coulomb attraction with a specific effect of strong intra-monomer electronic correlations, which results in effective intra-monomer electron-hole repulsion. Our approach allows to go beyond the single-chain picture and to compare excitons for polymers in solutions and in films. The approach helps connecting such different questions as shallow singlet and deep triplet excitons, stronger binding of interchain excitons in films, crossings of excitons' branches, 1/N energies shifts in oligomers. We describe a strong suppression of the luminescence from free charge carriers by long-range Coulomb interactions. Main attention is devoted to the most requested in applications phenyl based polymers. The specifics of the benzene ring monomer give rise to existence of three possible types of excitons: Wannier-Mott, Frenkel and intermediate ones. We discuss experimental manifestations of various excitons and of their transformations. We touch effects of the time-resolved self-trapping by libron modes leading to formation of torsion polarons. PMID:20517580

Brazovskii, Serguei; Kirova, Natasha

2010-07-01

84

Ion conducting organic/inorganic hybrid polymers  

Science.gov (United States)

This invention relates to a series of organic/inorganic hybrid polymers that are easy to fabricate into dimensionally stable films with good ion-conductivity over a wide range of temperatures for use in a variety of applications. The polymers are prepared by the reaction of amines, preferably diamines and mixtures thereof with monoamines with epoxy-functionalized alkoxysilanes. The products of the reaction are polymerized by hydrolysis of the alkoxysilane groups to produce an organic-containing silica network. Suitable functionality introduced into the amine and alkoxysilane groups produce solid polymeric membranes which conduct ions for use in fuel cells, high-performance solid state batteries, chemical sensors, electrochemical capacitors, electro-chromic windows or displays, analog memory devices and the like.

Meador, Maryann B. (Inventor); Kinder, James D. (Inventor)

2010-01-01

85

Electrochromic window with lithium conductive polymer electrolyte  

Digital Repository Infrastructure Vision for European Research (DRIVER)

An electrochromic window was built using WO3 as electrochromic material and V2O5 as counterelectrode. Both were deposited onto ITO-coated glass panes by vacuum evaporation and were amorphous to x-ray diffraction. The electrolyte was a lithium-conducting polymer consisting of a poly(ethylene oxide)-lithium salt complex. The electrochemical characterization of electrodes was realized by cyclic voltammetry, coulometric titration, and impedance spectroscopy, which allowed the determination of the...

Baudry, Paul; Aegerter, Michel A.; Deroo, Daniel; Valla, Bruno

1991-01-01

86

Electrochromic window with lithium conductive polymer electrolyte  

Digital Repository Infrastructure Vision for European Research (DRIVER)

An electrochromic window was built using WO3 as the electrochromic material and V2O5 as the counterelectrode. Both were deposited onto ITO coated glass panes by vacuum evaporation and were amorphous to X-ray diffraction. The electrolyte was a lithium conducting polymer constituted by a Poly (ethylene oxide) - lithium salt complex. The electrochemical characterization of electrodes was realized by cyclic voltammetry, coulometric titration, and impedance spectroscopy, which allowed the determin...

Baudry, Paul; Aegerter, Michel A.; Deroo, Daniel; Valla, Bruno

1991-01-01

87

Synthesis and characterization of soluble conducting polymers and conducting adhesives  

Science.gov (United States)

With the demanding nature of the technology today, scientists are looking for new materials in order to decrease the cost, increase the efficiency of the use of the materials, and decrease time-consuming steps in order to increase the speed of production. New materials are being studied to decrease the weight of cars, planes and space vehicles; surface properties are being modified to decrease the drag coefficient; new technologies are being introduced for speeding up applications in production and assembly lines. In this research we address the needs of different technological applications from a conductivity perspective. In the first part of the thesis, the synthesis of soluble conducting polymers in order to make them more processable for potential electronic and photovoltaic applications is presented. Soluble conducting polymers of 3-hexylthiophene, 3-octylthiophene, 3-decylthiophene and 3-dodecylthiophene were synthesized electrochemically and thus, doped during synthesis. It was found that the conductivities; molecular weights and degrees of polymerization of the polymers strongly depend on the side chain's length. The substitution of alkyl side chains decreases the reactivity of the growing chain, and with an increasing side-chain length, all of these properties show a decrease. The hexyl substituent, being the shortest of the four side chains, causes the least distortion in the background, has the highest conjugation, and has the highest shift in the UV spectrum when it polymerizes. As the length of the side chain increases, the shift in the UV spectrum decreases, too. Decrease in the pi-stacking, conjugation and delocalization decreases the conductivity. This gives the material an opportunity to be used in photovoltaic applications. In the second part of the thesis, a conducting adhesive formulation that eliminates the need for heat or other expensive and rather bothersome application methods to activate the adhesive is investigated. Using the quick setting feature of the cyanoacrylates, a fast and serviceable conducting adhesive is formulated. Environmentally stable and electrically conducting cyanoacrylate formulations have been successfully prepared by introducing silver particles into a stabilized cyanoacrylate formulation. Silver particles have been observed to increase the viscosity and decrease the thixotropicity of the formulations. The stability of the formulations was achieved by using excess amounts of anionic stabilizers. This excess amount of inhibitor increases the set time by delaying the start of the reaction. This inhibition problem was solved by introducing functional amine groups and accelerating the reaction. Addition of the amine groups created more nucleation sites on the surface, which competed with the stabilizer to start the reaction. The use of accelerators did not affect the adhesive strength of the bond, however, it did change the resistivity of the adhesive joint.

Oztemiz, Serhan

88

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.

Bin Wang

2010-04-01

89

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

International Nuclear Information System (INIS)

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

90

Tuning electrical conductivity and surface area of chemically-exfoliated graphene through nanocrystal functionalization  

Energy Technology Data Exchange (ETDEWEB)

Silver nanocrystals were used to prevent the stacking of exfoliated graphene and to improve its conductivity. They were deposited onto chemically-exfoliated graphene through self-assembly and subsequent reduction of silver ions. Characterization by X-ray diffraction and transmission electron microscopy has confirmed the formation of silver/graphene hybrid. The nitrogen adsorption/desorption tests indicated that the nanoparticles inhibited the restacking of these sheets, resulting in larger active surface areas. The electrical conductivity of silver-deposited graphene was increased by nearly 3 times. The hybrid material was also used as an electrode of a supercapacitor and the capacitance of 326 F g{sup -1} was achieved at a scan rate of 2 mV s{sup -1}. In contrast, as-produced chemically-exfoliated graphene based supercapacitors exhibited a capacitance of 109 F g{sup -1}. These results provide a valuable guidance for tuning the properties of chemically-exfoliated graphene in potential applications. -- Graphical abstract: Silver nanocrystals/graphene hybrids were fabricated by self-assembly and subsequent reduction. Compared to as-synthesized graphene sheets, the resultant hybrids exhibited improved electrical conductivity and surface area. The supercapacitors using as-produced hybrids as an electrode demonstrated a specific capacitance as high as 326 F g{sup -1}. Highlights: Black-Right-Pointing-Pointer We synthesize silver nanocrystals/graphene hybrid through in-situ ion assembly and reduction. Black-Right-Pointing-Pointer We examine the effect of nanocrystals attachment on electrical conductivity and surface area. Black-Right-Pointing-Pointer We examine the electrochemical behavior of silver/graphene-based supercapacitor. Black-Right-Pointing-Pointer We elucidate the role of electrode electrical conductivity and surface area in the supercapacity capacitance.

Zhang, Yue [Department of Industrial Engineering, Texas Tech University, 2500 Broadway, Lubbock, TX 79409 (United States); Wang, Shiren, E-mail: Shiren.Wang@ttu.edu [Department of Industrial Engineering, Texas Tech University, 2500 Broadway, Lubbock, TX 79409 (United States); Li, Li; Zhang, Kun [Department of Industrial Engineering, Texas Tech University, 2500 Broadway, Lubbock, TX 79409 (United States); Qiu, Jingjing [Department of Mechanical Engineering, Texas Tech University, 2500 Broadway Lubbock, TX 79409 (United States); Davis, Marauo; Hope-Weeks, Louisa J. [Department of Chemistry and Biochemistry, Texas Tech University, 2500 Broadway, Lubbock, TX 79409 (United States)

2012-08-15

91

Tuning electrical conductivity and surface area of chemically-exfoliated graphene through nanocrystal functionalization  

International Nuclear Information System (INIS)

Silver nanocrystals were used to prevent the stacking of exfoliated graphene and to improve its conductivity. They were deposited onto chemically-exfoliated graphene through self-assembly and subsequent reduction of silver ions. Characterization by X-ray diffraction and transmission electron microscopy has confirmed the formation of silver/graphene hybrid. The nitrogen adsorption/desorption tests indicated that the nanoparticles inhibited the restacking of these sheets, resulting in larger active surface areas. The electrical conductivity of silver-deposited graphene was increased by nearly 3 times. The hybrid material was also used as an electrode of a supercapacitor and the capacitance of 326 F g?1 was achieved at a scan rate of 2 mV s?1. In contrast, as-produced chemically-exfoliated graphene based supercapacitors exhibited a capacitance of 109 F g?1. These results provide a valuable guidance for tuning the properties of chemically-exfoliated graphene in potential applications. -- Graphical abstract: Silver nanocrystals/graphene hybrids were fabricated by self-assembly and subsequent reduction. Compared to as-synthesized graphene sheets, the resultant hybrids exhibited improved electrical conductivity and surface area. The supercapacitors using as-produced hybrids as an electrode demonstrated a specific capacitance as high as 326 F g?1. Highlights: ? We synthesize silver nanocrystals/graphene hybrid through in-situ ion assembly and reduction. ? We examine the effect of nanocrystals attachment on electrical conductivity and surface area. ? We examine the electrochemical behavior of silver/graphene-based supercapacitor. ? We elucidate the role of electrode electrical conductivity and surface area in the supercapacity capacitance.

2012-08-15

92

Single conducting polymer nanowire based conductometric sensors  

Science.gov (United States)

The detection of toxic chemicals, gases or biological agents at very low concentrations with high sensitivity and selectivity has been subject of immense interest. Sensors employing electrical signal readout as transduction mechanism offer easy, label-free detection of target analyte in real-time. Traditional thin film sensors inherently suffered through loss of sensitivity due to current shunting across the charge depleted/added region upon analyte binding to the sensor surface, due to their large cross sectional area. This limitation was overcome by use of nanostructure such as nanowire/tube as transducer where current shunting during sensing was almost eliminated. Due to their benign chemical/electrochemical fabrication route along with excellent electrical properties and biocompatibility, conducting polymers offer cost-effective alternative over other nanostructures. Biggest obstacle in using these nanostructures is lack of easy, scalable and cost-effective way of assembling these nanostructures on prefabricated micropatterns for device fabrication. In this dissertation, three different approaches have been taken to fabricate individual or array of single conducting polymer (and metal) nanowire based devices and using polymer by itself or after functionalization with appropriate recognition molecule they have been applied for gas and biochemical detection. In the first approach electrochemical fabrication of multisegmented nanowires with middle functional Ppy segment along with ferromagnetic nickel (Ni) and end gold segments for better electrical contact was studied. This multi-layered nanowires were used along with ferromagnetic contact electrode for controlled magnetic assembly of nanowires into devices and were used for ammonia gas sensing. The second approach uses conducting polymer, polypyrrole (Ppy) nanowires using simple electrophoretic alignment and maskless electrodeposition to anchor nanowire which were further functionalized with antibodies against cancer marker protein (Cancer Antigen, CA 125) using covalent immobilization for detection of CA 125 in buffer and human blood plasma. Third approach combined electrochemical deposition of conducting polymer and assembly steps into a single step fabrication & functionalization using e-beam lithographically patterned nano-channels. Using this method array of Ppy nanowires were fabricated. Further during fabrication step, by entrapping recognition molecule (avidin) biofunctionalization was achieved. Subsequently these sensors were used for detection of biotinylated single stranded DNA.

Bangar, Mangesh Ashok

93

Conducting Polymer Electrochemically Generated Via Anodic Oxidation of Toluene.  

Science.gov (United States)

As opposed to the much harsher conditions demanded in homogeneous solutions, a conducting polymer of toluene is readily formed by anodic oxidation of acetonitrile solutions containing the precursor. The fabrication of new conductive polymers is of interes...

D. B. Parry J. M. Harris K. Ashley S. Pons

1988-01-01

94

Superfluorescent Emission in Conducting Polymer Thin Films.  

Science.gov (United States)

We investigated the emission of photogenerated excitons in a series of conducting polymer films. The materials included derivatives of PPV, PPA, PPP, PT, and mixed systems composed of PPV and C_60, or PPV and polystyrene, respectively. As excitation sources we used ps and fs pulses with ?J energy levels in the UV/green spectral range. At low excitation intensities, the intrachain oligomeric sized singlet excitons in these solids give rise to broad, high quantum efficiency photoluminescence bands. Typical spontaneous emission lifetimes are several hundred ps, bandwidths 100 nm, and quantum efficiencies several 10me. The variation of the respectiv e SF threshold intensity in each polymer with film thickness, substrate, and solvent will be discussed.

Gellermann, W.; Shkunov, M. N.; Frolov, S. V.; Vardeny, Z. V.

1997-03-01

95

Electrochemical relaxation at electrically conducting polymers  

International Nuclear Information System (INIS)

In this study, slow relaxation (SR) associated with the electroreduction of polyaniline (PAn) films during polarization to high cathodic potentials was investigated by cyclic voltammetry technique. Anodic voltammetric currents were used as experimental variable to indicate the relaxation occurring in PAn films deposited electrochemically on the Pt electrode surface. The dependence of SR on polymer film thickness, waiting potential, and mobility of the doped anion was investigated. Percolation threshold potential for heteropolyanion doped PAn was estimated to be between 150 and 200 mV depending on polymer thickness on the electrode surface. A new model of the conducting to insulating conversion is described by the percolation theory and mobility gap changes during the process.

2008-08-01

96

Electrochemical relaxation at electrically conducting polymers  

Energy Technology Data Exchange (ETDEWEB)

In this study, slow relaxation (SR) associated with the electroreduction of polyaniline (PAn) films during polarization to high cathodic potentials was investigated by cyclic voltammetry technique. Anodic voltammetric currents were used as experimental variable to indicate the relaxation occurring in PAn films deposited electrochemically on the Pt electrode surface. The dependence of SR on polymer film thickness, waiting potential, and mobility of the doped anion was investigated. Percolation threshold potential for heteropolyanion doped PAn was estimated to be between 150 and 200 mV depending on polymer thickness on the electrode surface. A new model of the conducting to insulating conversion is described by the percolation theory and mobility gap changes during the process.

Nateghi, M R [Department of Chemistry, Islamic Azad University, Yazd-Branch, Yazd (Iran, Islamic Republic of); Zarandi, M B [Department of physics, Yazd University, Yazd (Iran, Islamic Republic of)

2008-08-15

97

Structural investigations and processing of electronically and protonically conducting polymers  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Various conducting polymers form a special class of materials with the potential for many applications in organic electronics and functional materials. These polymers can be electronically conducting or semiconducting due to a conjugated polymer backbone, or alternatively possess conductivity due to mobile protons or other ions. This thesis discusses such conducting polymers and shows ways how they can be processed by printing and how the nanostructure allows controlling their electrical prop...

Vilkman, Marja

2010-01-01

98

Conducting polymer-hydrogels for medical electrode applications  

International Nuclear Information System (INIS)

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. (topical review)

2010-02-01

99

Tunable surface plasmon resonance and enhanced electrical conductivity of In doped ZnO colloidal nanocrystals  

Science.gov (United States)

We report a new synthesis process of colloidal indium (In) doped zinc oxide (ZIO) nanocrystals by a hot injection technique. By fine tuning the synthesis we reached the same nucleation temperature for indium oxide and zinc oxide which helped us to study a dopant precursor dependent In incorporation into the ZnO matrix by using different In sources. The dopant induced shape evolution changes the hexagonal pyramid structured ZnO to a platelet like structure upon 8% In doping. The introduction of trivalent In3+ into the ZnO lattice and consequent substitution of divalent Zn2+ generates free electrons in the conduction band which produces a plasmonic resonance in the infrared region. The electron concentration controls plasmon frequency as well as the band gap of host ZnO. The variation of the band gap and the modification of the conduction band have been explained by the Burstein-Moss effect and Mie's theory respectively. The In dopant changes the defect chemistry of pure ZnO nanocrystals which has been studied by photoluminescence and other spectroscopic measurements. The nanocrystals are highly stable in the organic medium and can be deposited as a crack free thin film on different substrates. Careful ligand exchange and thermal annealing of the spin cast film lead to a good conductive film (720 ? per square to 120 ? per square) with stable inherent plasmonic absorption in the infrared and 90% transmittance in the visible region. A temperature induced metal-semiconductor transition was found for doped ZnO nanocrystals. The transition temperature shifts to a lower temperature with increase of the doping concentration.We report a new synthesis process of colloidal indium (In) doped zinc oxide (ZIO) nanocrystals by a hot injection technique. By fine tuning the synthesis we reached the same nucleation temperature for indium oxide and zinc oxide which helped us to study a dopant precursor dependent In incorporation into the ZnO matrix by using different In sources. The dopant induced shape evolution changes the hexagonal pyramid structured ZnO to a platelet like structure upon 8% In doping. The introduction of trivalent In3+ into the ZnO lattice and consequent substitution of divalent Zn2+ generates free electrons in the conduction band which produces a plasmonic resonance in the infrared region. The electron concentration controls plasmon frequency as well as the band gap of host ZnO. The variation of the band gap and the modification of the conduction band have been explained by the Burstein-Moss effect and Mie's theory respectively. The In dopant changes the defect chemistry of pure ZnO nanocrystals which has been studied by photoluminescence and other spectroscopic measurements. The nanocrystals are highly stable in the organic medium and can be deposited as a crack free thin film on different substrates. Careful ligand exchange and thermal annealing of the spin cast film lead to a good conductive film (720 ? per square to 120 ? per square) with stable inherent plasmonic absorption in the infrared and 90% transmittance in the visible region. A temperature induced metal-semiconductor transition was found for doped ZnO nanocrystals. The transition temperature shifts to a lower temperature with increase of the doping concentration. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr05608b

Ghosh, Sirshendu; Saha, Manas; de, S. K.

2014-05-01

100

Polymer composite material structures comprising carbon based conductive loads  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The present invention provides a polymer composite material structure comprising at least one layer of a foamed polymer composite material comprising a foamed polymer matrix and 0.1 wt% to 6 wt% carbon based conductive loads, such as e.g. carbon nanotubes, dispersed in the foamed polymer matrix. The polymer composite material structure according to embodiments of the present invention shows good shielding and absorbing properties notwithstanding the low amount of carbon based conductive loads...

2007-01-01

 
 
 
 
101

Polymer composite material structures comprising carbon based conductive loads  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The present invention provides a polymer composite material structure comprising at least one layer of a foamed polymer composite material comprising a foamed polymer matrix and 0.1 wt % to 6 wt % carbon based conductive loads, such as e.g. carbon nanotubes, dispersed in the foamed polymer matrix. The polymer composite material structure according to embodiments of the present invention shows good shielding and absorbing properties notwithstanding the low amount of carbon based conductive loa...

2007-01-01

102

Polymer composite material structures comprising carbon based conductive loads  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The present invention provides a polymer composite material structure comprising at least one layer of a foamed polymer composite material comprising a foamed polymer matrix and 0.1 to 6 wt% carbon based conductive loads, such as e.g. carbon nanotubes, dispersed in the foamed polymer matrix. The polymer composite material structure according to embodiments of the present invention shows good shielding and absorbing properties notwithstanding the low amount of carbon based conductive loads. Th...

2006-01-01

103

Biomimetic electrochemistry from conducting polymers. A review  

International Nuclear Information System (INIS)

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

104

Free volume and conductivity in polymer electrolytes  

International Nuclear Information System (INIS)

Positron annihilation lifetime spectroscopy (PALS) and impedance spectroscopy (IS) have been employed to study the effect of temperature and pressure on the DC conductivity (?DC) and the mean hole volume (Vh) of a NaPF6 ethylene oxide based polyurethane electrolyte. The DC conductivity of the polymer electrolyte displayed a characteristic non-Arrhenius temperature dependence yielding acceptable values for both the 'pseudo-activation energy' (B) and the 'zero mobility temperature' (T0) from a VTF fit. Vh(T) showed a linear increase of 0.53cm3(molK)-1. When extrapolating Vh(T) to 0K a temperature very close to T0 from the VTF fit was obtained, which suggests a free volume mediated conductivity mechanism. This suggestion is further supported by the linear dependence of ln(?DC(T)) on Vh-1(T). Conductivity was measured as a function of pressure (?DC(P)) with ln(?DC(P)) showing a characteristic decrease with increasing pressure. The activation volumes (VA) calculated from these measurements ranged from 45 to 20cm3mol-1 over a temperature from 304 to 365K. Critical volumes calculated from two current free-volume models were found to be unrealistic. Combining the extra volume required for ionic motion (VA) with the available free volume (Vh) at the same temperature poses a realistic and 'model-free' figure of 117cm3mol-1 for the critical volume at 304K. This equates roughly to the volume of 3-4 EO units. The pressure dependence of free volume (Vh(P)) for a polymer electrolyte has been measured for the first time, and yielded a linear decrease in Vh with increasing pressure. A linear dependence of ?DC(P) on Vh-1(P) was also found. A comparison of the isothermal and isobaric dependence of ?DC on Vh-1 illustrates the contribution of factors other than free volume have on charge carrier number and mobility. This comparison shows that the variation of Vh with temperature and the variation of Vh with pressure affect the conductivity in very different ways. These results clearly show that free volume cannot be considered the sole factor responsible for conductivity in polymer electrolytes

2005-06-30

105

Catalytic synthesis of metal crystals using conductive polymers  

Energy Technology Data Exchange (ETDEWEB)

A method of forming metal nanoparticles using a polymer colloid that includes at least one conductive polymer and at least one polyelectrolyte. Metal ions are reduced in water by the conductive polymer to produce the nanoparticles, which may be then incorporated in the colloidal structure to form a colloid composite. The method can also be used to separate selected metal ions from aqueous solutions.

Wang, Hsing-Lin (Los Alamos, NM); Li, Wenguang (Los Alamos, NM)

2008-01-15

106

Direct synthesis of II-VI compound nanocrystals in polymer matrix  

International Nuclear Information System (INIS)

The production of II-VI semiconductor compound - polymer matrix nanocomposites by a direct in-situ thermolysis process is described. Metal-thiolate precursor molecules embedded in a polymer matrix decompose by a thermal annealing and the nucleation of semiconductor nanocrystals occurs. It is shown that the nucleation of nanoparticles and the formation of the nanocomposite can be also achieved by laser beam irradiation; this opens the way towards a ''lithographic'' in-situ nanocomposite production process. A possible growth and nanocomposite formation mechanism, describing the structural and chemical transformation of the precursor molecules, their decomposition and the formation of the nanoparticles, is presented. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

2007-08-01

107

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

International Nuclear Information System (INIS)

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. (paper)

2012-02-24

108

Characterizations of proton conducting polymer electrolytes for electrochemical capacitors  

Energy Technology Data Exchange (ETDEWEB)

Solid polymer electrolytes containing phosphotungstic acid (PWA) and/or silicotungstic acid (SiWA) in polyvinyl alcohol (PVA) were investigated for their proton conductivities. Enhanced conductivity was obtained when mixing PWA and SiWA at equal ratio. This polymer electrolyte was found viable for electrochemical capacitors. Thermal and structural analyses were conducted with DSC, XRD, and FTIR. The polymer electrolyte exhibited a different structure and different thermal properties from its respective components. The polymer electrolyte retained its original Keggin structure but contained crystallized protonated water in the form of H{sub 5}O{sub 2}{sup +}. The protonated water may contribute to the proton conductivity of the polymer electrolyte.

Gao Han [Department of Materials Science and Engineering, University of Toronto, 184 College St. Toronto, Toronto, Ont., M5S 3E4 (Canada); Lian, Keryn, E-mail: keryn.lian@utoronto.c [Department of Materials Science and Engineering, University of Toronto, 184 College St. Toronto, Toronto, Ont., M5S 3E4 (Canada)

2010-12-15

109

Conductive polymer patterned media for scanning multiprobe data storage  

Energy Technology Data Exchange (ETDEWEB)

Conductive polymer dot arrays as a patterned medium have been developed for scanning multiprobe data storage based on scanning probe microscopy (SPM) technology. The dot array is formed using electron beam lithography, and the conductive polymer is synthesized by selective electrolytic polymerization from a self-assembled monolayer on an Au film. The conductance of the conductive polymer dots can be reversibly changed by the application of voltages using a conductive SPM tip. It is demonstrated that the conductive polymer has the potential ability for the patterned media of scanning probe data storage systems.

Yoshida, Shinya; Ono, Takahito; Esashi, Masayoshi [Graduate School of Engineering, Tohoku University, 6-6-01 Aza-Aoba-Aramaki, Aoba-Ku, Sendai, Miyagi 980-8579 (Japan)

2007-12-19

110

Conductive polymer patterned media for scanning multiprobe data storage  

International Nuclear Information System (INIS)

Conductive polymer dot arrays as a patterned medium have been developed for scanning multiprobe data storage based on scanning probe microscopy (SPM) technology. The dot array is formed using electron beam lithography, and the conductive polymer is synthesized by selective electrolytic polymerization from a self-assembled monolayer on an Au film. The conductance of the conductive polymer dots can be reversibly changed by the application of voltages using a conductive SPM tip. It is demonstrated that the conductive polymer has the potential ability for the patterned media of scanning probe data storage systems

2007-12-19

111

Biodegradable and electrically conducting polymers for biomedical applications  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Conducting polymers have been widely used in biomedical applications such as biosensors and tissue engineering but their non-degradability still poses a limitation. Therefore, great attention has been directed toward the recently developed degradable and electrically conductive polymers (DECPs). The different strategies for synthesis of degradable and conducting polymers containing conducting oligomers are summarized and discussed here as well as the influence of different macromolecular arch...

Guo, Baolin; Glavas, Lidija; Albertsson, Ann-christine

2013-01-01

112

A polymer electrolyte with high luminous transmittance and low solar throughput: Polyethyleneimine-lithium bis(trifluoromethylsulfonyl) imide with In2O3:Sn nanocrystals  

Science.gov (United States)

Chemically prepared ~13-nm-diameter nanocrystals of In2O3:Sn were included in a polyethyleneimine-lithium bis(trifluoromethylsulfonyl) imide electrolyte and yielded high haze-free luminous transmittance and strong near-infrared absorption without deteriorated ionic conductivity. The optical properties could be reconciled with effective medium theory, representing the In2O3:Sn as a free electron plasma with tin ions screened according to the random phase approximation corrected for electron exchange. This type of polymer electrolyte is of large interest for opto-ionic devices such as laminated electrochromic smart windows.

Bayrak Pehlivan, ?.; Runnerstrom, E. L.; Li, S.-Y.; Niklasson, G. A.; Milliron, D. J.; Granqvist, C. G.

2012-06-01

113

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

2010-07-01

114

Mesoscopic modelling of conducting and semiconducting polymers  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We present generalized Monte Carlo calculations to assess the effects of texture and related key factors on the properties of polymer-based light emitting diodes. We, describe one class of mesoscopic model giving specific realizations of the polymer network. The model, with simple physically based rules, shows the effects of polymer structural order on current flow, trapping and radiative and non-radiative charge recombination within the polymer layer. Interactions between charges are include...

Stoneham, A. M.; Ramos, Marta M. D.

2001-01-01

115

Electrochemical post-functionalization of conducting polymers.  

Science.gov (United States)

This article summarizes recent progress in the post-functionalization of conjugated polymers by electrochemical methods. These electrochemical polymer reactions typically proceed via electrochemical doping of a conjugated polymer film, followed by chemical transformation. Examples include the quantitative oxidative fluorination of polyfluorenes and oxidative halogenation of polythiophenes, as well as the reductive hydrogenation of polyfluorenones. The degree of functionalization, otherwise known as the reaction ratio, can be controlled by varying the charge passed through the polymer, allowing the optoelectronic properties of the conjugated polymers to be tailored. Wireless bipolar electrodes with an in-plane potential distribution are also useful with regard to the electrochemical doping and reaction of conjugated polymers and allow the synthesis of films exhibiting composition gradients. Such bipolar electrochemistry can induce multiple reaction sites during electrochemical polymer reactions. PMID:24590504

Inagi, Shinsuke; Fuchigami, Toshio

2014-05-01

116

Current Trends in Sensors Based on Conducting Polymer Nanomaterials  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 buil...

2013-01-01

117

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

2013-06-25

118

Electrochemical Impedance Spectroscopy of Conductive Polymer Coatings  

Science.gov (United States)

Electrochemical impedance spectroscopy (EIS) was used to investigate the corrosion protection performance of twenty nine proprietary conductive polymer coatings for cold rolled steel under immersion in 3.55 percent NaCl. Corrosion potential as well as Bode plots of the data were obtained for each coating after one hour immersion, All coatings, with the exception of one, have a corrosion potential that is higher in the positive direction than the corrosion potential of bare steel under the same conditions. Group A consisted of twenty one coatings with Bode plots indicative of the capacitive behavior characteristic of barrier coatings. An equivalent circuit consisting of a capacitor in series with a resistor simulated the experimental EIS data for these coatings very well. Group B consisted of eight coatings that exhibited EIS spectra showing an inflection point which indicates that two time constants are present. This may be caused by an electrochemical process taking place which could be indicitive of coating failing. These coatings have a lower impedance that those in Group A.

Calle, Luz Marina; MacDowell, Louis G.

1996-01-01

119

Conducting polymer supported bilayer lipid membrane reconstituted with alamethicin  

International Nuclear Information System (INIS)

Ionic electroactive polymers and bioderived materials have been independently demonstrated as actuators, sensors and energy harvesting devices. In an electroactive polymer, the applied electric field between the cathode and anode drives ion transport between the electrodes, impregnated electrolyte and the bulk of the polymer to generate force and displacement. Similarly, in a bioderived material an input stimulus (electrical, chemoelectrical or chemical) applied across the protein in a bilayer lipid membrane (BLM) displaces ions across the membrane barrier and enables sensing and actuation functions. This paper presents a novel architecture for a device that integrates the ionic function of an electroactive polymer and a bioderived material into a thin-film laminated device combining their unique advantages. A conducting polymer (PPy(DBS)) is used as the electroactive polymer and alamethicin-bound bilayer lipid membrane is used as the bioderived material in the thin-film laminated device. Owing to the configuration of the laminated device, the protein regulates the ionic concentration in the conducting polymer and regulates the electrochemical doping/undoping process in the polymer. By electrically connecting the conducting polymer across its thickness, this arrangement provides a mechanism external to the polymer besides electrical field that can control the electrical, mechanical and/or optical properties of the conducting polymer. This paper also presents the fabrication and characterization of the integrated ionic device and presents a template for the development of a novel category of electroactive ionic devices

2011-09-01

120

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

Science.gov (United States)

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°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, Anna Maria; Resta, Vincenzo; Piscopiello, Emanuela; Miceli, Valerio; Schioppa, Monica; Scalone, Anna Grazia; Benedetto, Francesca Di; Tapfer, Leander

2013-09-01

 
 
 
 
121

Anion-conducting polymer, composition, and membrane  

Science.gov (United States)

Anion-conducing polymers and membranes with enhanced stability to aqueous alkali include a polymer backbone with attached sulfonium, phosphazenium, phosphazene, and guanidinium residues. Compositions also with enhanced stability to aqueous alkali include a support embedded with sulfonium, phosphazenium, and guanidinium salts.

Pivovar, Bryan S. (Los Alamos, NM); Thorn, David L. (Los Alamos, NM)

2011-11-22

122

Anion-Conducting Polymer, Composition, and Membrane  

Energy Technology Data Exchange (ETDEWEB)

Anion-conducing polymers and membranes with enhanced stability to aqueous alkali include a polymer backbone with attached sulfonium, phosphazenium, phosphazene, and guanidinium residues. Compositions also with enhanced stability to aqueous alkali include a support embedded with sulfonium, phosphazenium, and guanidinium salts.

Pivovar, Bryan S. (Los Alamos, NM); Thorn, David L. (Los Alamos, NM)

2008-10-21

123

Anion-conducting polymer, composition, and membrane  

Energy Technology Data Exchange (ETDEWEB)

Anion-conducing polymers and membranes with enhanced stability to aqueous alkali include a polymer backbone with attached sulfonium, phosphazenium, phosphazene, and guanidinium residues. Compositions also with enhanced stability to aqueous alkali include a support embedded with sulfonium, phosphazenium, and guanidinium salts.

Pivovar, Bryan S. (Los Alamos, NM); Thorn, David L. (Los Alamos, NM)

2010-12-07

124

Anion-conducting polymer, composition, and membrane  

Energy Technology Data Exchange (ETDEWEB)

Anion-conducing polymers and membranes with enhanced stability to aqueous alkali include a polymer backbone with attached sulfonium, phosphazenium, phosphazene, and guanidinium residues. Compositions also with enhanced stability to aqueous alkali include a support embedded with sulfonium, phosphazenium, and guanidinium salts.

Pivovar, Bryan S. (Los Alamos, NM); Thorn, David L. (Los Alamos, NM)

2009-09-01

125

Proton-conducting electrolyte membranes based on aromatic condensation polymers  

International Nuclear Information System (INIS)

The results of investigations in the field of development and applications of proton-conducting electrolyte membranes based on aromatic condensation polymers are analysed and summarised. Primary attention is paid to the properties of the starting polymers, such as the thermal stability, water uptake and proton conductivity. General approaches to the preparation of aromatic condensation polymers with high proton conductivity are considered, including sulfonation, synthesis from monomers containing sulfonic acid groups, incorporation of alkylsulfonated substituents and formation of acid-basic polymer complexes. The bibliography includes 115 references.

2002-09-30

126

Electrically Conductive Metal Nanowire Polymer Nanocomposites  

Science.gov (United States)

This thesis investigates electrically conductive polymer nanocomposites formulated with metal nanowires for electrostatic discharge and electromagnetic interference shielding. Copper nanowires (CuNWs) of an average length of 1.98 mum and diameter of 25 +/- 4 nm were synthesized. The oxidation reaction of the CuNWs in air can be divided into two stages at weight of 111.2% on TGA curves. The isoconversional activation energies determined by Starink method were used to fit the different master plots. Johnson-Mehl-Avrami (JMA) equation gave the best fit. The surface atoms of the CuNWs are the sites for the random nucleation and the crystallite strain in the CuNWs is the driving force for the growth of nuclei mechanism during the oxidation process. To improve the anti-oxidation properties of the CuNWs, silver was coated onto the surface of the CuNWs in Ag-amine solution. The prepared silver coated CuNWs (AgCuNWs) with silver content of 66.52 wt. %, diameter of 28--33 nm exhibited improved anti-oxidation behavior. The electrical resistivity of the AgCuNW/low density polyethylene (LDPE) nanocomposites is lower than that of the CuNW/LDPE nanocomposites with the same volume percentage of fillers. The nanocomposites formulated with CuNWs and polyethylenes (PEs) were compared to study the different interaction between the CuNWs and the different types of PE matrices. The electrical conductivity of the different PE matrices filled with the same concentrations of CuNWs correlated well with the level of the CuNW dispersion. The intermolecular force and entanglement resulting from the different macromolecular structures such as molecular weight and branching played an important role in the dispersion, electrical properties and rheological behaviour of the CuNW/PE nanocomposites. Ferromagnetic polycrystalline nickel nanowires (NiNWs) were synthesized with uniform diameter of ca. 38 nm and an average length of 2.68 mum. The NiNW linear low density polyethylene (LLDPE) nanocomposites exhibited electrical percolation threshold at NiNW volume fraction of 0.005. The power law fitting results imply that the electrical conductivity of the NiNW/LLDPE nanocomposites mainly originated from the contact among individual nanowires.

Luo, Xiaoxiong

127

Solar cells based on colloidal nanocrystals  

CERN Document Server

This book presents a new system of solar cells. Colloidal nanocrystals possess many physical and chemical properties which can be manipulated by advanced control over structural features like the particle size. One application field is photovoltaics where colloidal semiconductor nanocrystals are explored as components of photo-active layers which can be produced from liquid media, often in combination with conductive polymers. The further development of this interdisciplinary field of research requires a deep understanding of the physics and chemistry of colloidal nanocrystals, conducting poly

Borchert, Holger

2014-01-01

128

Polymer nanoparticles to decrease thermal conductivity of phase change materials  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Microparticles including paraffin are currently used for textiles coating in order to deaden thermal shocks. We will show that polymer nanoparticles embedded in those microsized capsules allow for decreasing the thermal conductivity of the coating and enhance the protection in the stationary regime. A reasonable volume fraction of polymer nanoparticles reduces the conductivity more than predicted by Maxwell mixing rules. Besides, measurements prove that the polymer nanoparti...

Chapuis, Po; Saha, Sourabh Kumar; Volz, S.

2007-01-01

129

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

International Nuclear Information System (INIS)

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

130

Photoelectrochemistry of conducting polymers. [Polypyrrole, polythiophene, polyaniline, polyazulene  

Energy Technology Data Exchange (ETDEWEB)

The authors conclude that conducting polymers, which have only been available for a few years, have successfully been used to, at least partially, solve one of the fundamental problems of semiconductor photoelectrochemistry, namely photocorrosion of small bandgap semiconductor photoelectrodes. The high electronic conductivity in combination with large surface area imply unique possibilities for surface modification. Incorporation of catalysts in the electronically conducting polymer opens up new possibilities for directing photoprocesses to fuel production. And, finally, even though some properties of conducting polymers render them interesting for active photovoltaic energy conversion in electrochemical systems, the low rate of photogeneration of charge carriers is still a limiting problem. 61 references, 5 figures.

Inganaes, O.; Skotheim, T.A.; Lundstroem, I.

1983-01-01

131

Printable Highly Conductive Conjugated Polymer Sensitized ZnO NCs as Cathode Interfacial Layer for Efficient Polymer Solar Cells.  

Science.gov (United States)

We report a facile way to produce printable highly conductive cathode interfacial layer (CIL) for efficient polymer solar cells (PSCs) by sensitizing ZnO nanocrystals (NCs) with a blue fluorescent conjugated polymer, poly(9, 9-bis-(6'-diethoxylphosphorylhexyl) fluorene) (PFEP). Herein, PFEP plays dual distinctive roles in the composite. Firstly, PFEP chains can effectively block the aggregation of ZnO NCs, leading to uniform and smooth film during solution processing via assembly on ZnO NC surfaces through their pending phosphonate groups. Secondly, PFEP can greatly improve the conductivity of ZnO NCs by charge transfer doping, that is the charge transfer from the sensitizer driven by electron-chemical potential equilibrium, which could be even more pronounced under light illumination because of light excitation of PFEP sensitizer. The increased conductivity in ZnO-PFEP layer renders more efficient electron transport and extraction compared to pristine ZnO layer. This ZnO-PFEP CIL was successfully applied to PSCs based on three polymer donor systems with different band-gaps, and efficiency enhancements from 44 to 70% were observed compared to those PSCs with pristine ZnO CIL. The highest efficiency of 7.56% was achieved in P(IID-DTC):PC70BM-based PSCs by using ZnO-PFEP film as CIL. Moreover, the enhanced conductivity due to the charge-transfer doping effect allows thick ZnO-PFEP film to be used as CIL in high-performance PSCs. Both the high conductivity and good film-forming properties of ZnO-PFEP CIL are favorable for large-scale printable PSCs, which is also verified by high-efficiency PSCs with ZnO-PFEP CIL fabricated using doctor-blading, a large-scale processing technique. The work provides an efficient printable cathode interfacial material for efficient PSCs. PMID:24842752

Liu, Jian; Wu, Jiang; Shao, Shuyan; Deng, Yunfeng; Meng, Bin; Xie, Zhiyuan; Geng, Yanhou; Wang, Lixiang; Zhang, Fengling

2014-06-11

132

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

International Nuclear Information System (INIS)

Thin films composed of Ge nanocrystals embedded in an amorphous SiO2 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.

2011-03-25

133

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

Energy Technology Data Exchange (ETDEWEB)

Thin films composed of Ge nanocrystals embedded in an amorphous SiO{sub 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, M A; Conibeer, G, E-mail: bo.zhang@student.unsw.edu.au [ARC Photovoltaics Centre of Excellence, University of New South Wales, Sydney, New South Wales 2052 (Australia)

2011-03-25

134

Conducting-polymer-based supercapacitor devices and electrodes  

Energy Technology Data Exchange (ETDEWEB)

Supercapacitor electrodes and devices that utilise conducting polymers are envisaged to bridge the gap between existing carbon-based supercapacitors and batteries to form units of intermediate specific energy. This review looks at the major conducting polymer materials, namely, polyaniline, polypyrrole, polythiophene and derivatives of polythiophene, as well as composites of these materials with carbon nanotubes and inorganic battery materials. Various treatments of the conducting polymer materials to improve their properties are considered and comparisons are made with other supercapacitor materials such as carbon and with inorganic battery materials. Conducting polymers are pseudo-capacitive materials, which means that the bulk of the material undergoes a fast redox reaction to provide the capacitive response and they exhibit superior specific energies to the carbon-based supercapacitors (double-layer capacitors). In general conducting polymers are more conductive than the inorganic battery materials and consequently have greater power capability. On the downside, conducting polymers swell and contract substantially on charge and discharge, respectively. Consequently, cycle-life is poor compared with carbon-based supercapacitors which generally only charge via adsorption and desorption of ions (giving typically a few thousand cycles for conducting polymers compared with >500 000 cycles for carbon-based devices). (author)

Snook, Graeme A. [CSIRO Process Science and Engineering, Box 312, Clayton South, Victoria 3169 (Australia); Kao, Pon; Best, Adam S. [CSIRO Energy Technology, Box 312, Clayton South, Victoria 3169 (Australia)

2011-01-01

135

Conductive polymers: towards a smart biomaterial for tissue engineering.  

Science.gov (United States)

Developing stimulus-responsive biomaterials with easy-to-tailor properties is a highly desired goal of the tissue engineering community. A novel type of electroactive biomaterial, the conductive polymer, promises to become one such material. Conductive polymers are already used in fuel cells, computer displays and microsurgical tools, and are now finding applications in the field of biomaterials. These versatile polymers can be synthesised alone, as hydrogels, combined into composites or electrospun into microfibres. They can be created to be biocompatible and biodegradable. Their physical properties can easily be optimized for a specific application through binding biologically important molecules into the polymer using one of the many available methods for their functionalization. Their conductive nature allows cells or tissue cultured upon them to be stimulated, the polymers' own physical properties to be influenced post-synthesis and the drugs bound in them released, through the application of an electrical signal. It is thus little wonder that these polymers are becoming very important materials for biosensors, neural implants, drug delivery devices and tissue engineering scaffolds. Focusing mainly on polypyrrole, polyaniline and poly(3,4-ethylenedioxythiophene), we review conductive polymers from the perspective of tissue engineering. The basic properties of conductive polymers, their chemical and electrochemical synthesis, the phenomena underlying their conductivity and the ways to tailor their properties (functionalization, composites, etc.) are discussed. PMID:24556448

Balint, Richard; Cassidy, Nigel J; Cartmell, Sarah H

2014-06-01

136

Non-aqueous proton conducting polymer gel electrolytes  

International Nuclear Information System (INIS)

A new family of non-aqueous proton conducting polymer gel electrolytes containing different weak acids namely aromatic carboxylic acids have been prepared by using polyvinylidenefluoride (PVdF) and polyvinylidene fluoride-co-hexafluoropropylene (PVdF-HFP) as the gelling polymers. These gel electrolytes possess high value of conductivity in the range of 10-3 to 10-4 S/cm at room temperature, which has been found to depend upon the dissociation constant of the acid used. PVdF and PVdF-HFP provide good dimensional stability to these gel electrolytes and the addition of polymer has also been found to result in an increase in conductivity, i.e. ? (gel) > ? (liquid) which suggests that the polymer does not play a passive role but also affects the conduction process. From FTIR studies it has been observed that the polymer enhances the dissociation of acid in these gel electrolytes resulting in an increase in carrier concentration

2004-11-30

137

Raising the conductivity of crystalline polymer electrolytes by aliovalent doping.  

Science.gov (United States)

Polymer electrolytes, salts dissolved in solid polymers, hold the key to realizing all solid-state devices such as rechargeable lithium batteries, electrochromic displays, or SMART windows. For 25 years conductivity was believed to be confined to amorphous polymer electrolytes, all crystalline polymer electrolytes were thought to be insulators. However, recent results have demonstrated conductivity in crystalline polymer electrolytes, although the levels at room temperature are too low for application. Here we show, for the first time, that it is possible to raise significantly the level of ionic conductivity by aliovalent doping. The conductivity may be raised by 1.5 orders of magnitude if the SbF6- ion in the crystalline conductor poly(ethylene oxide)6:LiSbF6 is replaced by less than 5 mol % SiF6(2-), thus introducing additional, mobile, Li+ ions into the structure to maintain electroneutrality. PMID:16366585

Zhang, Chuhong; Staunton, Edward; Andreev, Yuri G; Bruce, Peter G

2005-12-28

138

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

2007-10-01

139

Transmitter function of synapse-structure system using conducting polymer  

International Nuclear Information System (INIS)

Conducting polymers with neuron-like pattern has been polymerized by controlling polymerization conditions. These conducting polymers have been connected each other to prepare network. If the synapse function can be added to the network, artificial neural network is prepared by conducting polymer. In this paper, we consider the transmitter function using synapse-structure conducting polymer. It consists of three parts: primary circuit as presynaptic terminal, space as synaptic cleft and secondary circuit as postsynaptic structure. Dopant in conducting polymer works as neurotransmitter. Migration as well as diffusion is also considered for dopant ion to transit the space/cleft. When signals from the primary circuit came at the end of the primary circuit in electrolyte solution, the current in the secondary circuit increased because the released dopant ion transited the cleft and entered another conducting polymer. When two primary circuits was used, the current in the secondary circuit increased higher than one primary circuit. This means the synapse-structured conducting polymer system can be use as logical circuit.

2012-04-18

140

Making Conductive Polymers By Arc Tracking  

Science.gov (United States)

Experimental technique for fabrication of electrically conductive polymeric filaments based on arc tracking, in which electrical arc creates conductive carbon track in material that initially was insulator. Electrically conductive polymeric structures made by arc tracking aligned along wire on which formed. Alignment particularly suited to high conductivity and desirable in materials intended for testing as candidate superconductors.

Daech, Alfred F.

1992-01-01

 
 
 
 
141

Unusually conductive carbon-inherently conducting polymer (ICP) composites: Synthesis and characterization  

Science.gov (United States)

Two groups of materials that have recently come to the forefront of research initiatives are carbon allotropes, especially nanotubes, and conducting polymers-more specifically inherently conducting polymers. The terms conducting polymers and inherently conducting polymers sometimes are used interchangeably without fully acknowledging a major difference in these terms. Conducting polymers (CPs) and inherently conducting polymers (ICPs) are both polymeric materials that conduct electricity, but the difference lies in how each of these materials conducts electricity. For CPs of the past, an electrically conductive filler such as metal particles, carbon black, or graphite would be blended into a polymer (insulator) allowing for the CP to carry an electric current. An ICP conducts electricity due to the intrinsic nature of its chemical structure. The two materials at the center of this research are graphite and polyaniline. For the first time, a composite between carbon allotropes (graphite) and an inherently conducting polymer (PANI) has exhibited an electrical conductivity greater than either of the two components. Both components have a plethora of potential applications and therefore the further investigation could lead to use of these composites in any number of technologies. Touted applications that use either conductive carbons or ICPs exist in a wide range of fields, including electromagnetic interference (EMI) shielding, radar evasion, low power rechargeable batteries, electrostatic dissipation (ESD) for anti-static textiles, electronic devices, light emitting diodes (LEDs), corrosion prevention, gas sensors, super capacitors, photovoltaic cells, and resistive heating. The main motivation for this research has been to investigate the connection between an observed increase in conductivity and structure of composites. Two main findings have resulted from the research as related to the observed increase in conductivity. The first was the structural evidence from Raman spectroscopy, X-ray diffraction, and thermal analysis suggesting a more crystalline graphite matrix due to intimate interactions with PANI that resulted in a charge transfer. Confirmation of charge transfer was observed through magnetic susceptibility, electron paramagnetic resonance, and temperature dependent electrical conductivity studies.

Bourdo, Shawn Edward

142

Polyfuran Conducting Polymers: Synthesis, Properties, and Applications.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this review, polyfuran (PFu) synthesis methods and the nucleation mechanism; the electrochemical, structural, morphological, and magnetic properties of PFu; thermal behavior; theoretical calculations on PFu, as well as its applications reported to date, have been compiled. Not only PFu homopolymers have been reviewed, but also PFu co-polymers, PFu bipolymers, and PFu composites. The results are listed, discussed, and compared. It is hoped that this assembly of all the relevant data might e...

Gonza?lez-tejera, M. J.; Sa?nchez La Blanca, Emilia; Carrillo Ramiro, Isabel

2008-01-01

143

Synthesis and characterization of electrically conducting polymers: Polypyrrole  

Energy Technology Data Exchange (ETDEWEB)

For future device applications of electrically conducting polymers, a dry vacuum processing technique for preparation and modification of conducting polymers compatible with silicon technology has been developed. This process is similar to Chemical Vapour Deposition or CVD. Conducting polypyrrole films have been synthesized from vapour phase using iron III chloride water and pyrrole monomers in an ultra high vacuum system or hydrogen peroxide, hydrochloric acid and pyrrole monomers in a high vacuum system. The results of a variety of physical and chemical characterization studies that CVD-prepared polypyrrole is very similar to that prepared by conventional wet (electro)chemical techniques. The increase of order and orientation is essential to realize the optimum properties of conducting polymers, and also in order to understand their fundamental limitations. The use of polymer matrices could be one route towards the synthesis of more ordered forms of conducting polymers. In this thesis, we report on the results of preparation and characterization of conducting polypyrrole/poly(4-vinylpyridine) composite films using a template-polymerization process. The matrix polymer used is a complex of an oxidant (copper or iron) and poly(4-vinylpyridine). It has e.g., been possible to fabricate transparent polypyrrole films with rather high conductivities. The thesis comprises 6 papers.

Mohammaddi, Asghar.

1989-01-01

144

Electropolymerized Conducting Polymer as Actuator and Sensor Device  

Science.gov (United States)

A study demonstrates the potential application of conducting polymers to convert electrical energy into mechanical energy at low voltage or current. The performance of the device is explained using electrochemistry and solid-state chemistry.

Cortes, Maria T.; Moreno, Juan C.

2005-01-01

145

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

Science.gov (United States)

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. PMID:22816386

Lee, Jonghun; Lee, Sunghwan; Li, Guanglai; Petruska, Melissa A; Paine, David C; Sun, Shouheng

2012-08-15

146

On the Surface of Conducting Polymers : Electrochemical Switching of Color and Wettability in Conjugated Polymer Devices  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Since the discovery in 1977 that conjugated polymers can be doped to achieve almost metallic electronic conduction, the research field of conducting polymers has escalated, with applications such as light emitting diodes, solar cells, thin film transistors, electrochemical transistors, logic circuits and sensors. The materials can be chemically modified during their synthesis in order to tailor the desired mechanical, electronic and optical properties of the final product. Polymers are also g...

Isaksson, Joakim

2005-01-01

147

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. D. Deshpande

2002-05-01

148

Conductivity hysteresis in polymer electrolytes incorporating poly(tetrahydrofuran)  

Energy Technology Data Exchange (ETDEWEB)

Conductivity hysteresis and room temperature ionic conductivities >10{sup -3}S/cm were recently reported for electrolytes prepared from blends of an amphiphilic comb copolymer, poly[2,5,8,11,14-pentaoxapentadecamethylene (5-hexadecyloxy-1,3-phenylene)] (polymer I), and a linear multiblock copolymer, poly(oligotetrahydrofuran-co-dodecamethylene) (polymer II), following thermal treatment [F. Chia, Y. Zheng, J. Liu, N. Reeves, G. Ungar, P.V. Wright, Electrochim. Acta 43 (2003) 1939]. To investigate the origin of these effects, polymers I and II were synthesized in this work, and the conductivity and thermal properties of the individual polymers were investigated. AC impedance measurements were conducted on I and II doped with LiBF{sub 4} or LiClO{sub 4} during gradual heating to 110{sup o}C and slow cooling to room temperature. Significant conductivity hysteresis was seen for polymer II, and was similarly observed for poly(tetrahydrofuran) (PTHF) homopolymer at equivalent doping levels. From thermogravimetric analysis (TGA), gel permeation chromatography (GPC) and {sup 1}H NMR spectroscopy, both polymer II and PTHF were found to partially decompose to THF during heat treatment, resulting in a self-plasticizing effect on conductivity. (author)

Akbulut, Ozge; Taniguchi, Ikuo; Mayes, Anne M. [Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA (United States); Kumar, Sundeep; Shao-Horn, Yang [Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA (United States)

2007-01-01

149

A quantitative evaluation of metallic conduction in conjugated polymers  

CERN Document Server

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

150

Electrochemical characterization of conducting polymers: polypyrrole  

Energy Technology Data Exchange (ETDEWEB)

The nature of the interaction between dopant ions and a polypyrrole host matrix is investigated. In the highly reversible form of polypyrrole used here, two types of site for dopant anions seem to exist: a set of well-defined sites that are occupied in a cooperative process at low dopant levels, and a number of less well-defined sites with varying potential energies, possibly owing to local variations in the conformation of the polymer chains. The dopant ion diffusion coefficient is approximately 50 times higher for anions occupying the disordered sites compared with those occupying the ordered sites. (orig.).

West, K.; Zachau-Christiansen, B.; Jacobsen, T. (Dept. of Physical Chemistry, Technical Univ. of Denmark, Lyngby (Denmark)); Skaarup, S. (Physics Lab. 3, Technical Univ. of Denmark, Lyngby (Denmark))

1992-04-15

151

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

International Nuclear Information System (INIS)

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.

2013-06-01

152

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

153

Photoinduced electron transfer from a conducting polymer to buckminsterfullerene  

Energy Technology Data Exchange (ETDEWEB)

Evidence for photoinduced electron transfer form the excited state of a conducting polymer onto buckminsterfullerene, C{sub 60}, is reported. After photo-excitation of the conjugated polymer with light of energy greater than the {pi}-{pi} gap, an electron transfer to the C{sub 60} molecule is initiated. Photoinduced optical absorption studies demonstrate a different excitation spectrum for the composite as compared to the separate components, consistent with photo-excited charge transfer. A photoinduced electron spin resonance signal exhibits signatures of both the conducting polymer cation and the C{sub 60} anion. Because the photoluminescence in the conducting polymer is quenched by interaction with C{sub 60}, the data imply that charge transfer form the excited state occurs on a picosecond time scale. The charge-separated state in composite films is metastable at low temperatures. 34 refs., 4 figs.

Sarciftci, N.S.; Smilowitz, L.; Heeger, A.J. [Univ. of California, Santa Barbara, CA (United States)] [and others

1992-11-27

154

FTIR AND IONIC CONDUCTIVITY STUDIES ON BLEND POLYMER ELECTROLYTES  

Directory of Open Access Journals (Sweden)

Full Text Available Investigations on structural and conductivity properties of solid polymer complexes have attracted a high degree of attention. The main applications of solid polymer electrolytes (SPEs are found in varioussecondary batteries and energy conversion units. In view of the abundant resources, low costs and relatively low reactivity of magnesium, solid-state batteries using magnesium metal are worthy of investigations. The polymer electrolytes were prepared using poly methyl methacrylate (PMMA, poly vinyl chloride (PVC and magnesium chloride (MgCl2 by solvent casting technique. The complex formation and ionic conductivity were characterized by Fourier Transform Infra Red spectroscopy (FTIR and impedance spectroscopy respectively.The FTIR studies provide the evidence of interaction of cation Mg2+ with the polymers. The maximum conductivity found for PMMA-MgCl2 is 0.57 x 10-7 Scm-1 at room temperature.

J. Senthil

2011-08-01

155

Conductive AFM microscopy study of the carrier transport and storage in Ge nanocrystals grown by dewetting  

International Nuclear Information System (INIS)

A combined conductive atomic force microscope (C-AFM)/scanning electron microscope (SEM) has been used to study the electric transport and retention mechanisms through Ge nanocrystals (NCs). The NCs were formed by a two-step dewetting/nucleation process on a silicon oxide layer grown on n-doped (001) silicon substrate. Without preliminary e-beam irradiation, electric images are obtained only with bias voltages larger than 8 V. This is due to the barrier height introduced by the presence of the native oxide on NCs and of the oxide layer on which the NCs are grown. After acquisition of an e-beam-induced current image, electric images (e-beam off) can be easily obtained at low bias voltages because of the trap creation in the oxide layer. We show that the critical threshold voltage to detect a current through the NCs decreases with NCs size. The band diagram of the contact in the presence of a p-doped diamond coated tip shows that the conduction mechanism is dominated by holes. At last we show a good memory effect with charge/discharge in the NCs resulting in a long retention time.

2010-02-10

156

Top-down prepared silicon nanocrystals and a conjugated polymer-based bulk heterojunction: Optoelectronic and photovoltaic applications  

International Nuclear Information System (INIS)

Blends consisting of doped silicon nanocrystals (Si-ncs) and two conjugated polymers (poly(3-hexylthiophene) (P3HT) and poly(methoxy ethylexyloxy phenylenevinilene) (MEH PPV)) with improved photostability were fabricated. We show that a top-down approach by electrochemical etching is suitable for preparing doped (boron and phosphorus) freestanding and surfactant-free Si-ncs. The doping of Si-ncs was confirmed by low temperature photoluminescence and electron spin resonance analysis. It is demonstrated that such Si-ncs can be successfully used for the fabrication of room temperature photoluminescent and photosensitive blends. We argue that the luminescence and transport properties of the blends are controlled by the Si-ncs properties and could be assigned to quantum confinement of excitons in nanocrystalites with an energy band gap of ?2 eV. Furthermore, the blending of doped Si-ncs in both conjugated polymers led to the establishment of a bulk heterojunction between the Si-ncs and polymer. The difference in electron affinity and ionization potential between nanocrystals and polymer dissociated the excitons. Those blends showed increased carrier transport and photoconductivity under ambient conditions. It was found that introduction of less defective p-type doped Si-ncs significantly improved overall photostability of the blend. The Si-ncs non-toxicity and easy integration into well-established silicon technologies might bring considerable benefit for hybrid optoelectronic and photovoltaic device development.

2009-12-01

157

Top-down prepared silicon nanocrystals and a conjugated polymer-based bulk heterojunction: Optoelectronic and photovoltaic applications  

Energy Technology Data Exchange (ETDEWEB)

Blends consisting of doped silicon nanocrystals (Si-ncs) and two conjugated polymers (poly(3-hexylthiophene) (P3HT) and poly(methoxy ethylexyloxy phenylenevinilene) (MEH PPV)) with improved photostability were fabricated. We show that a top-down approach by electrochemical etching is suitable for preparing doped (boron and phosphorus) freestanding and surfactant-free Si-ncs. The doping of Si-ncs was confirmed by low temperature photoluminescence and electron spin resonance analysis. It is demonstrated that such Si-ncs can be successfully used for the fabrication of room temperature photoluminescent and photosensitive blends. We argue that the luminescence and transport properties of the blends are controlled by the Si-ncs properties and could be assigned to quantum confinement of excitons in nanocrystalites with an energy band gap of {approx}2 eV. Furthermore, the blending of doped Si-ncs in both conjugated polymers led to the establishment of a bulk heterojunction between the Si-ncs and polymer. The difference in electron affinity and ionization potential between nanocrystals and polymer dissociated the excitons. Those blends showed increased carrier transport and photoconductivity under ambient conditions. It was found that introduction of less defective p-type doped Si-ncs significantly improved overall photostability of the blend. The Si-ncs non-toxicity and easy integration into well-established silicon technologies might bring considerable benefit for hybrid optoelectronic and photovoltaic device development.

Svrcek, Vladimir, E-mail: vladimir.svrcek@aist.go.jp [Novel Silicon Material Team, Research Center for Photovoltaics, National Institute of Advanced Industrial Science and Technology (AIST), Central 2, Umezono 1-1-1, Tsukuba 305-8568 (Japan); Fujiwara, Hiroyuki; Kondo, Michio [Novel Silicon Material Team, Research Center for Photovoltaics, National Institute of Advanced Industrial Science and Technology (AIST), Central 2, Umezono 1-1-1, Tsukuba 305-8568 (Japan)

2009-12-15

158

Effective thermal conductivity of isotropic polymer composites  

Energy Technology Data Exchange (ETDEWEB)

The effective thermal conductivity of tin powder filled high density polyethylene composites is investigated experimentally as a function of filler concentration and the measured values are compared with the existing theoretical and empirical models. Samples are prepared by compression molding process, up to 16% volumetric concentration of tin particles. The thermal conductivity is measured by a modified hot wire technique in a temperature range from about 0 to 70 C. Experimental results show a region of low particle content, up to about 10% volume concentration, where the increase in thermal conductivity is rather slow. The filler particles are dispersed in the matrix material in this region, the thermal conductivity is best predicted by Maxwell`s model and Nielsen`s model with A = 1.5, {phi}{sub m} = 0.637. Whereas, at high filler concentrations, the filler particles tend to form agglomerates and conductive chains in the direction of heat flow resulting in a rapid increase in thermal conductivity. A model developed by Agari and Uno estimates the thermal conductivity in this region, using two experimentally determined constants.

Tavman, I.H. [Dokuz Eyluel Univ., Izmir (Turkey). Mechanical Engineering Dept.

1998-07-01

159

The Effect Of Dopant, Temperature And Band Gap On Conductivity Of Conducting Polymers  

Directory of Open Access Journals (Sweden)

Full Text Available Polymers By Virtue Of Light Weight And Greater Easy Of Fabrication, Have Replaced And Are Continuing To Replace Metals In Several Areas Of Applications. Polymers With Conjugated ? Electron Backbones Displays Unusual Electronic Properties Such As Low Energy Optical Transitions, Low Ionization Potentials And High Electron Affinities. They Have Been Considered As Good Electrical Insulators And A Variety Of Their Applications Have Been Based Upon The Insulating Property. Polymers Which Are Conjugated Exhibit Semiconducting Behaviour And Can Be Doped To Give Materials With High Conductivity. Conducting Polymers Represent An Important Research Area With Diverse Scientific Problems Of Fundamental Significance And The Potential For Commercial Applications. The Effect Of Dopant On Conductivity, Mechanism Of Conduction, The Effect Of Band Gap And Temperature Has Been Studied. Conducting Polymers Like Poly Pyrrole, Poly Aniline And Poly Thiophene Etc. Have Been Synthesized And Their Conductivities Have Been Determined. Some Polar Organic Materials Such As Poly (Ethylene Oxide Will Complex Alkali Salts And Manifest Rapid Alkali-Ion Conductivity. Although The Absolute Conductivities Of Such Polymer Based Materials Are Not As High As Those Of Crystalline Solid Electrolytes In General, These May Be Made Into Thin Pin Hole-Free Plastic Sheets With Sufficient Conductance For Use In Cells And Batteries.

S.SRILALITHA, K.N.JAYAVEERA, S.S.MADHVENDHRA

2013-07-01

160

Solution synthesis and electrochemical capacitance performance of Mn3O4 polyhedral nanocrystals via thermolysis of a hydrogen-bonded polymer  

International Nuclear Information System (INIS)

Research highlights: ? A hydrogen-bonded polymer was used to synthesize Mn3O4 polyhedral nanocrystals. ? Ligand plays an important role in the formation of Mn3O4 polyhedral nanocrystals. ? Mn3O4 polyhedral nanocrystals displayed electrochemical capacitance performance in 0.5 M Na2SO4 electrolyte. - Abstract: Hausmannite Mn3O4 polyhedral nanocrystals have been successfully synthesized via a simple solution-based thermolysis route using a three-dimensional hydrogen-bonded polymer as precursor. The as-obtained product was characterized by means of powder X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). Possible formation mechanism of polyhedral nanocrystals was proposed based on the role of organic ligand dissociation from the polymer precursor at elevated temperature. The electrochemical capacitance performance of Mn3O4 electrode was investigated by cyclic voltammetry and galvanostatic charge/discharge measurements. A maximum specific capacitance of 178 F g-1 was obtained for the nanocrystals in a potential range from -0.1 to 0.8 V vs. SCE in a 0.5 M sodium sulfate solution at a current density of 0.2 A g-1.

2011-04-15

 
 
 
 
161

Solution synthesis and electrochemical capacitance performance of Mn{sub 3}O{sub 4} polyhedral nanocrystals via thermolysis of a hydrogen-bonded polymer  

Energy Technology Data Exchange (ETDEWEB)

Research highlights: {yields} A hydrogen-bonded polymer was used to synthesize Mn{sub 3}O{sub 4} polyhedral nanocrystals. {yields} Ligand plays an important role in the formation of Mn{sub 3}O{sub 4} polyhedral nanocrystals. {yields} Mn{sub 3}O{sub 4} polyhedral nanocrystals displayed electrochemical capacitance performance in 0.5 M Na{sub 2}SO{sub 4} electrolyte. - Abstract: Hausmannite Mn{sub 3}O{sub 4} polyhedral nanocrystals have been successfully synthesized via a simple solution-based thermolysis route using a three-dimensional hydrogen-bonded polymer as precursor. The as-obtained product was characterized by means of powder X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). Possible formation mechanism of polyhedral nanocrystals was proposed based on the role of organic ligand dissociation from the polymer precursor at elevated temperature. The electrochemical capacitance performance of Mn{sub 3}O{sub 4} electrode was investigated by cyclic voltammetry and galvanostatic charge/discharge measurements. A maximum specific capacitance of 178 F g{sup -1} was obtained for the nanocrystals in a potential range from -0.1 to 0.8 V vs. SCE in a 0.5 M sodium sulfate solution at a current density of 0.2 A g{sup -1}.

Zhang Fang [College of Material Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Zhang Xiaogang, E-mail: azhangxg@163.com [College of Material Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Hao Liang [College of Material Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China)

2011-04-15

162

Influence of chain length and defects on the electrical conductivity of conducting polymers  

Energy Technology Data Exchange (ETDEWEB)

In-situ conductivity measurements were carried out on a defined conjugated oligomer and the corresponding conducting polymer, i.e. p-sexiphenylene and polyphenylene respectively. At low doping levels the conductivity of the oligomer is better than that of the polymer. By contrast, at high doping levels the situation is inverse. This may be explained in terms of two different conductivity mechanisms, hopping between chains and chain conductivity respectively. For the first time, the influence of chain length and the number of defects on the overall electrical conductivity was studied quantitatively during solid state electropolymerization of p-sexiphenylene. The conductivity of the polymer with the longest experimentally accessible chains exceeded that of p-sexiphenylene by about two orders of magnitude. Cross-linking of these chains lead to a dramatic decrease of the conductivity. (orig.)

Meerholz, K. (Inst. fuer Physikalische Chemie der Univ. Freiburg, Freiburg i. Br. (Germany) Freiburger Materialforschungszentrum, Freiburg i. Br. (Germany)); Heinze, J. (Inst. fuer Physikalische Chemie der Univ. Freiburg, Freiburg i. Br. (Germany) Freiburger Materialforschungszentrum, Freiburg i. Br. (Germany))

1993-04-19

163

Intercalation of ionically conductive polymers into Lithium Hectorite  

Science.gov (United States)

Renewable energy sources such as wind and solar have become appealing sources of energy with low environmental impact. However, the challenge with using these energy sources is their intermittent and unpredictable power generation. In order to overcome this challenge, energy storage mechanisms such as lithium-ion batteries are dependable systems for such applications. The purpose of this project is intended to synthesize environmentally benign and safe materials which can be used as electrolytes in lithium-ion batteries. The ionically conductive polymers POEGO, POMOE, and MEEP were successfully intercalated into the two-dimensional layered structure Lithium Hectorite. The goal of the project was to synthesize a series of nanocomposites with increasing polymer molar ratios to Lithium Hectorite, and investigate the thermal and ionic conductivity properties of the synthesized nanocomposites. A second series of nanocomposites using the same polymer molar ratio to Lithium Hectorite were synthesized after the polymers were complexed with lithium triflate. The salt-complexed nanocomposites were compared to the pristine nanocomposites based on thermal stability, polymer flexibility, as well as their ionic conductivity. The synthesized polymers, nanocomposites, and salt-complexed materials were characterized using powder X-ray diffraction, attenuated total reflectance spectroscopy, thermogravimetric analysis, and differential scanning calorimetry. Ionic conductivity data was investigated using AC impedance spectroscopy.

Saada, Iskandar

164

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

165

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

166

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

167

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

168

Multifunctional polymer-derivatized {gamma}-Fe{sub 2}O{sub 3} nanocrystals as a methodology for the biomagnetic separation of recombinant His-tagged proteins  

Energy Technology Data Exchange (ETDEWEB)

Multifunctional polymer-derivatized superparamagnetic iron oxide ({gamma}-Fe{sub 2}O{sub 3}) 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 {gamma}-Fe{sub 2}O{sub 3} 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 {gamma}-Fe{sub 2}O{sub 3} nanocrystals was monitored by UV-vis spectroscopy and light microscopy. Protein immobilization and separation was monitored using immunostaining techniques and gel electrophoresis, respectively.

Shukoor, M.I. [Institut fuer Anorganische Chemie und Analytische Chemie, Johannes Gutenberg-Universitaet, Duesbergweg 10-14, 55099 Mainz (Germany); Natalio, F. [Institut fuer Physiologische Chemie, Abteilung fuer Angewandte Molekulargenetik, Johannes Gutenberg-Universitaet, D-55099 Mainz (Germany); Tahir, M.N. [Institut fuer Anorganische Chemie und Analytische Chemie, Johannes Gutenberg-Universitaet, Duesbergweg 10-14, 55099 Mainz (Germany); Divekar, M. [Institut fuer Physiologische Chemie, Abteilung fuer Angewandte Molekulargenetik, Johannes Gutenberg-Universitaet, D-55099 Mainz (Germany); Metz, N. [Institut fuer Organische Chemie der Johannes Gutenberg-Universitaet, D-55099 Mainz (Germany); Therese, H.A. [Institut fuer Anorganische Chemie und Analytische Chemie, Johannes Gutenberg-Universitaet, Duesbergweg 10-14, 55099 Mainz (Germany); Theato, P. [Institut fuer Organische Chemie der Johannes Gutenberg-Universitaet, D-55099 Mainz (Germany); Ksenofontov, V. [Institut fuer Anorganische Chemie und Analytische Chemie, Johannes Gutenberg-Universitaet, Duesbergweg 10-14, 55099 Mainz (Germany); Schroeder, H.C.; Mueller, W.E.G. [Institut fuer Physiologische Chemie, Abteilung fuer Angewandte Molekulargenetik, Johannes Gutenberg-Universitaet, D-55099 Mainz (Germany); Tremel, W. [Institut fuer Anorganische Chemie und Analytische Chemie, Johannes Gutenberg-Universitaet, Duesbergweg 10-14, 55099 Mainz (Germany)], E-mail: tremel@uni-mainz.de

2008-10-15

169

Multifunctional polymer-derivatized ?-Fe 2O 3 nanocrystals as a methodology for the biomagnetic separation of recombinant His-tagged proteins  

Science.gov (United States)

Multifunctional polymer-derivatized superparamagnetic iron oxide (?-Fe 2O 3) 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 ?-Fe 2O 3 nanocrystals, a 6× 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 Mössbauer and the polymer functionalization of the ?-Fe 2O 3 nanocrystals was monitored by UV-vis spectroscopy and light microscopy. Protein immobilization and separation was monitored using immunostaining techniques and gel electrophoresis, respectively.

Shukoor, M. I.; Natalio, F.; Tahir, M. N.; Divekar, M.; Metz, N.; Therese, H. A.; Theato, P.; Ksenofontov, V.; Schröder, H. C.; Müller, W. E. G.; Tremel, W.

170

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

2008-10-01

171

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 â?? 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

172

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

173

Stabilization of zinc electrodes with a conducting polymer  

Energy Technology Data Exchange (ETDEWEB)

The reversibility of zinc anode in alkaline medium was enhanced by electrostatic deposition of a conducting polymer (polypyrrole). Electropolymerization of pyrrole onto zinc in aqueous medium using an organic acid as dopant is feasible and preferred as zinc is less corrosive in this medium. The structure of the polymer film was analyzed by FT-IR spectroscopy and scanning electron microscopy. The effect of the polypyrrole deposit on the zinc electrode was studied by cyclic voltammetry and charge-discharge cycling. (author)

Vatsalarani, J.; Geetha, S.; Trivedi, D.C.; Warrier, P.C. [Central Electrochemical Research Institute, Karaikudi 630006 (India)

2006-08-25

174

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

175

Synergism in binary nanocrystal superlattices leads to enhanced p-type conductivity in self-assembled PbTe/Ag2Te thin films  

Science.gov (United States)

The ordered cocrystallization of nanoparticles into binary superlattices enables close contact of nanocrystals with distinct physical properties, providing a route to `metamaterials' design. Here we present the first electronic measurements of multicomponent nanocrystal solids composed of PbTe and Ag2Te, demonstrating synergistic effects leading to enhanced p-type conductivity. First, syntheses of size-tuneable PbTe and Ag2Te nanocrystals are presented, along with deposition as thin-film nanocrystal solids, whose electronic transport properties are characterized. Next, assembly of PbTe and Ag2Te nanocrystals into AB binary nanocrystal superlattices is demonstrated. Furthermore, binary composites of varying PbTe-Ag2Te stoichiometry (1:1 and 5:1) are prepared and electronically characterized. These composites show strongly enhanced (conductance ~100-fold increased in 1:1 composites over the sum of individual conductances of single-component PbTe and Ag2Te films) p-type electronic conductivity. This observation, consistent with the role of Ag2Te as a p-type dopant in bulk PbTe, demonstrates that nanocrystals can behave as dopants in nanostructured assemblies.

Urban, Jeffrey J.; Talapin, Dmitri V.; Shevchenko, Elena V.; Kagan, Cherie R.; Murray, Christopher B.

2007-02-01

176

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

177

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

178

Conducting polymers of aniline. Pt. 1; Electrochemical synthesis of a conducting composite  

Energy Technology Data Exchange (ETDEWEB)

We describe an electrochemical synthesis of a conducting composite of polyaniline. Poly(bisphenol A carbonate) was used as the insulating polymer matrix. Composite characterization was made using FT-IR, SEM and DSC data. The conductivities of the composites seemed to be in the order of pure polyaniline as prepared by the same method. Moreover, the above-mentioned methods reveal that the resultant composites have different properties compared to a simple mechanical mixture of the two polymers. (orig.)

Dogan, S. (Dept. of Chemistry, Middle East Technical Univ., Ankara (Turkey)); Akbulut, U. (Dept. of Chemistry, Middle East Technical Univ., Ankara (Turkey)); Toppare, L. (Dept. of Sciences, Middle East Technical Univ., Ankara (Turkey))

1992-11-01

179

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

180

Non-aqueous proton conducting polymer gel electrolytes  

Energy Technology Data Exchange (ETDEWEB)

A new family of non-aqueous proton conducting polymer gel electrolytes containing different weak acids namely aromatic carboxylic acids have been prepared by using polyvinylidene fluoride (PVdF) and polyvinylidene fluoride-co-hexafluoropropylene (PVdF-HFP) as the gelling polymers. These gel electrolytes possess high value of conductivity in the range of 10{sup -3} to 10{sup -4} S/cm at room temperature, which has been found to depend upon the dissociation constant of the acid used. PVdF and PVdF-HFP provide good dimensional stability to these gel electrolytes and the addition of polymer has also been found to result in an increase in conductivity, i.e. {sigma} (gel) > {sigma} (liquid) which suggests that the polymer does not play a passive role but also affects the conduction process. From FTIR studies it has been observed that the polymer enhances the dissociation of acid in these gel electrolytes resulting in an increase in carrier concentration. (Author)

Singh, Harinder Pal; Sekhon, S.S. [Guru Nanak Dev Univ., Dept. of Applied Physics, Amritsar (India)

2004-11-30

 
 
 
 
181

Advanced materials made of conducting polymers and bisfulleroid composites  

Science.gov (United States)

Chapter I gives a general insight about my three topics: fullerene, conducting polymer, and TTF chemistry, which include major possible applications for each field. Chapter II provides the novel idea of functionalizing fullerene without disturbing its aromaticity. The preparation, characterization, photophyscial and electrochemical properties of homoconjugated bisfulleroids with a variety of substitutents are described. This research paves the way for better understanding the nature of homoconjugative effect in these systems. Chapter III presents a concept of making homoconjugated bisfulleroid polymer, which takes advantage of our model system in Chapter II. This approach is to prevent phase separation existed in the conventional conducting polymer and fullerene mixture for active layer in photovoltaic devices. The resulting polymer shows very low bandgap (ca. 0.25 eV) and acts as a good photodiode. Chapter IV reports the first synthesis of neutral green conducting polymer, which serves as a key component in the electrochromic devices. In this chapter, electrochemical properties, spectroelectrochemistry, and switching stability of the green polymer have been described. A hypothesis concerning the green color is also provided with some supporting experimental data. Chapter V focuses on synthesis of amphiphilic PPEs, photophysical properties and self-assembly of the resulting polymer in different solvent systems. A preparation of self-assemblied PPE/silica nanocomposites, which forms a hexagonal array, is also described. Chapter VI illustrates the discovery of new TTF-o-chloranil adducts; one of them is neutral, covalent-bonded benzodioxane, which is confirmed by X-ray crystallography and another is a charge-transfer radical ionic salt, which exhibited a strong ESR signal. Conductivity measurement and ESI-MS study strongly suggest that the structure of this particular radical ion salt is that of a traditional organic metal; i.e., segregated, partially charged stacks of TTF and o-CA. The neutral adduct can also undergo covalent-to-ionic transition under a variety of conditions.

Shen, Kwang-Fu

182

Corrosion-protective coatings from electrically conducting polymers  

Science.gov (United States)

In a joint effort between NASA Kennedy and LANL, electrically conductive polymer coatings were developed as corrosion protective coatings for metal surfaces. At NASA Kennedy, the launch environment consist of marine, severe solar, and intermittent high acid and/or elevated temperature conditions. Electrically conductive polymer coatings were developed which impart corrosion resistance to mild steel when exposed to saline and acidic environments. Such coatings also seem to promote corrosion resistance in areas of mild steel where scratches exist in the protective coating. Such coatings appear promising for many commercial applications.

Thompson, Karen Gebert; Bryan, Coleman J.; Benicewicz, Brian C.; Wrobleski, Debra A.

1991-01-01

183

Corrosion-protective coatings from electrically conducting polymers  

Energy Technology Data Exchange (ETDEWEB)

In a joint research effort involving the Kennedy Space Center and the Los Alamos National Laboratory, electrically conductive polymer coatings have been developed as corrosion-protective coatings for metal surfaces. At the Kennedy Space Center, the launch environment consists of marine, severe solar, and intermittent high acid/elevated temperature conditions. Electrically conductive polymer coatings have been developed which impart corrosion resistance to mild steel when exposed to saline and acidic environments. Such coatings also seem to promote corrosion resistance in areas of mild steel where scratches exist in the protective coating. Such coatings appear promising for many commercial applications.

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

1991-01-01

184

Corrosion-protective coatings from electrically conducting polymers  

Energy Technology Data Exchange (ETDEWEB)

In a joint research effort involving the Kennedy Space Center and the Los Alamos National Laboratory, electrically conductive polymer coatings have been developed as corrosion-protective coatings for metal surfaces. At the Kennedy Space Center, the launch environment consists of marine, severe solar, and intermittent high acid/elevated temperature conditions. Electrically conductive polymer coatings have been developed which impart corrosion resistance to mild steel when exposed to saline and acidic environments. Such coatings also seem to promote corrosion resistance in areas of mild steel where scratches exist in the protective coating. Such coatings appear promising for many commercial applications.

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

1991-12-31

185

Direct patterning of conductive polymer domains for photovoltaic devices.  

Science.gov (United States)

We report a simple approach to control the morphology of polymer/fullerene solar cells based on electron-beam patterning of polymer semiconductors. This process generates conductive nanostructures or microstructures through an in situ cross-linking reaction, where the size, shape, and density of polymer domains are all tunable parameters. Cross-linked polymer structures are resistant to heat and solvents, so they can be incorporated into devices that require thermal annealing or solution-based processing. We demonstrate this method by building "gradient" and nanostructured poly(3-hexylthiophene)/fullerene solar cells. The power-conversion efficiency of these model devices improves with increasing interfacial area. The flexible methodology can be used to study the effects of active layer design on optoelectronic function. PMID:22817649

Moungthai, Suchanun; Mahadevapuram, Nikhila; Ruchhoeft, Paul; Stein, Gila E

2012-08-01

186

The effect of ion-polymer binding on ionic diffusion in dicarbazole-based conducting polymers  

Energy Technology Data Exchange (ETDEWEB)

An electrochemical polymerization and characterization is reported on a series of eight dicarbazole-type conducting polymers with different attached functional groups. The influence of the electronic character of the subgroup on the ionic conductivity properties of the polymers was examined. Impedance spectroscopy measurements were used to set the ionic chemical diffusion coefficients, D, in the polymer matrix at a variety of doping levels, for each of the polydicarbazoles. We relate D dependency with potential to morphological and electronic processes in the polymer occurring during oxidation. By combination of cyclic voltammetry and impedance spectroscopy for part of the series we reveal that the diffusion of ions in the matrix is easier in polymers were the functional group is highly electron-attracting. (author)

Pomerantz, Zvika; Joseph, Augustine; Lellouche, Jean-Paul; Zaban, Arie [Department of Chemistry, Bar-Ilan University, Ramat-Gan 52900 (Israel); Garcia-Belmonte, Germa; Bisquert, Juan [Departament de Fisica, Universitat Jaume I, 12071 Castello (Spain)

2007-08-01

187

Photovoltaic Cells with TiO2 Nanocrystals and Conjugated Polymer Composites  

International Nuclear Information System (INIS)

Various compositional photovoltaic cells based on the blend of poly(3-hexylthiophene) (P3HT) as donors and TiO2 nanocrystals as acceptors are fabricated and investigated. It is demonstrated that the blend ratio of P3HT and TiO2 nanocrystals could greatly influence the performance of the photovoltaic cells. The maximum of 0.411% in power conversion efficiency under AM 1.5, 100mW/cm2, and 44.4% of fill factor are obtained in the solar cell with the blend weight ratio 1:1 of P3HT and TiO2 nanocrystals. The function of nanocrystal composition is discussed in terms of the results of photoluminescence spectroscopy, atomic force microscopy, transmission electron microscopy, and charge transport I–V curve. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

2008-08-01

188

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

189

Electrical and surface properties of clay-conducting polymer composites  

Science.gov (United States)

Organic guests such as aniline, pyrrole and thiophene polymerize on the surface and in the intergallery regions of smectite clays which contain exchangeable transition metal cations such as Cu2+ and Fe3+. We monitor these reactions in thin films of smectite clays using electron spin resonance (ESR) and impedance spectroscopies. Polymers that form on the surface and in the interlayer region are studied by scanning force microscopy (SFM). ESR studies have shown that the transition metal ions are reduced during the polymerization process. Impedance measurements indicate that the formation of conducting polymer in the interlayer region of dry, Cu2+ exchanged hectorite thin films results in a dramatic reduction in observed impedance. SFM scans indicate that the conducting polymers can adopt a variety of morphologies on the surfaces of the films and within the intergalleries of the host framework. These studies have applications in the development of advanced materials including microsensors and novel nanocomposites.

Eastman, M. P.; Hagerman, M. E.; Porter, T. L.; Parnell, R. A.; Attuso, J. L.; Bradley, M.; Thompson, D.

1997-08-01

190

Finite element modeling of piezoelectric bimorphs with conductive polymer electrodes  

Science.gov (United States)

The purpose of my research has been to find a good way to solve for the mechanical and electrical behavior of piezoelectric polymer bimorphs which are electroded with a low to medium conductivity material. Traditionally, metal with very high conductivity has been used as the electrode material. Any applied voltage to an electrode will be distributed nearly instantaneously and uniformly throughout the electrode. Because of this quality, the voltage was assumed to be known and uniform for any applied voltage signal, including high frequency signals. The disadvantage of metal is that it is stiffer than polymers, and thus impedes the bending of the bimorph to a greater extent than for comparable polymer electrodes. With the modern invention of conductive polymers with acceptably high conductivities, it is now possible to manufacture piezoelectric devices with finite conductivity electrodes. For all but the very lowest frequencies of applied voltage signals, the voltage distribution cannot be assumed to be uniform throughout the electrode, nor can it be assumed to be exactly in phase. With finite conductivity electrodes there will be a loss in voltage amplitude due to resistivity, and there will also be a phase lag. The piezoelectric problem involves solving a coupled set of differential equations which involve mechanical displacement and electric potential. The electrical behavior of the electrodes is also included in the formulation, so that the voltage distribution in the electrodes is solved for simultaneously with the mechanical displacement and electric potential in the piezoelectric sheets. In this dissertation the coupled set of differential equations was solved using the Finite Element Method with quadratic Lagrange finite elements. The piezoelectric polymer which was modeled was polyvinylidene fluoride (PVDF). The conductive polymer of interest was PEDOT-PSS, although the model is valid for any type of isotropic finite conductivity material. The results of the work show that for moderate conductivity, the mechanical response of the bimorph is very good. There will not be a large phase lag within the first frequency mode. The bimorph resonates at low frequencies, and so any large effect from finite conductivity would only occur at higher modes.

Lediaev, Laura Marie

191

Robust solid polymer electrolyte for conducting IPN actuators  

International Nuclear Information System (INIS)

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. (paper)

2013-10-01

192

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

193

Applications of conductive polymers; Les applications des polymeres conducteurs  

Energy Technology Data Exchange (ETDEWEB)

Researches at the Cea concerning conductive polymers, aimed at gaining a better knowledge of their electric and physical properties, are briefly reviewed. Applications may include their combination with other materials for processing or properties objectives such as electromagnetic materials (radar and infrared stealth materials), electrochemical materials (batteries...), optical materials (electro-luminescent diodes), electrical materials (heating systems, cable semiconductors...)

Olmedo, L. [CEA Centre d`Etudes du Ripault, 37 - Tours (France)

1997-12-31

194

Flexible polymer electronic devices using highly conductive polyaniline electrode  

Science.gov (United States)

Camphor sulfonic acid doped conducting polyaniline (PANI:CSA) was synthesized by self-stabilized dispersion polymerization (SSDP). Well ordered polymer chains grow at the interface between aqueous and organic phase at low temperature around -35 °C. Thus, the growing polymer chains act as a stabilizer, producing high quality polyaniline with high electrical conductivity and with low content of structural defects. Moreover, the PANI:CSA thin film shows an apparent Drude peak in the infrared region with a high d.c. conductivity of 550 Scm-1, and a high transmittance in the visible region. Using this highly conducting polyaniline as a transparent electrode, flexible polymer light-emitting diodes (PLEDs) and flexible polymer solar cells (PSCs) were fabricated on flexible poly(ethersulfone) (PES) substrates. The flexible PLEDs show high performance with a luminance of 2300 cdm-2 and a luminous efficiency of 1.6 cdA-1. In addition, flexible PSCs based on composites of regioregular poly (3-hexylthiophene) (rr-P3HT) as an electron donor and phenyl-C61-butyric acid methyl ester (PCBM) as an electron acceptor exhibit a reasonable power conversion efficiency (PCE) of 1.8 %.

Lee, Byoung Hoon; Back, Hyung Cheol; Park, Sung Heum; Lee, Kwanghee

2009-08-01

195

Electrically conductive polymer concrete overlay installed in Pulaski, Virginia  

Energy Technology Data Exchange (ETDEWEB)

We report the development of a premixed electrically conductive polymer concrete overlay for use on bridge decks and other concrete members, in conjunction with cathodic protection systems. The development of a conductive overlay culminated in the installation of such an overlay on a full-bridge deck in Pulaski, Virginia; the active cathodic protection system has operated for eight months and is being monitored on a monthly basis. The monitoring shall continue for about 18 months. 11 refs., 18 figs., 1 tab.

Fontana, J.J.; Reams, W.; Elling, D.

1988-02-01

196

Soft capacitor fibers using conductive polymers for electronic textiles  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 si...

Gu, Jian Feng; Gorgutsa, Stephan; Skorobogatiy, Maksim

2010-01-01

197

Functionalised hybrid materials of conducting polymers with individual wool fibers.  

Science.gov (United States)

Composites of natural protein materials, such as merino wool, with the conducting polymers polypyrrole (PPy) and polyaniline (PAn) have been successfully synthesised. In doing so, hybrid materials have been produced in which the mechanical strength and flexibility of the fibers is retained whilst also incorporating the desired chemical and electrical properties of the polymer. Scanning electron microscopy shows PPy coatings to comprise individual polymer spheres, approximately 100 to 150 nm in diameter. The average size of the polymer spheres of PAn was observed to be approximately 50 to 100 nm in diameter. These spheres fuse together in a continuous sheet to coat the fibers in their entirety. The reduction of silver ions to silver metal nanoparticles onto the redox active polymer surface has also been successful and thus imparts anti-microbial properties to the hybrid materials. This gives rise to further applications requiring the inhibition of microbial growth. The chemical and physical characterisation of such products has been undertaken through scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), electrical conductivity, cyclic voltammetry, X-ray photoelectron spectroscopy (XPS) and the testing of their anti-microbial activity. PMID:18572600

Kelly, Fern M; Johnston, James H; Borrmann, Thomas; Richardson, Michael J

2008-04-01

198

Enhanced thermal conductivity in plate-shaped polymer parts  

Science.gov (United States)

Thermal conductive polymers are used more and more often, because of their specific range of properties. In many cases anisotropic thermal conductive fillers (platelets or fibers) are used to increase the thermal conductivity, because of their better potential to form conduction pathways. Usually, the thermal conductivity in thickness direction in plate-shaped polymer parts is the lowest of all directions. The reason for this effect can be found in the filler orientation inside the part. For many technical processes a high thermal conductivity in thickness direction is more important than a high planar thermal conductivity. Therefore, a new extrusion nozzle will be presented in the following article, which increases the thermal conductivity in thickness direction significantly. It has been shown, that the use of the new extrusion nozzle will achieve an improved filler orientation inside the part. This leads to an about 4 times higher heat flux through a planar plate compared to a conventional extrusion nozzle. Inside the new extrusion nozzle an elongation flow is induced at the end of the nozzle and the conductive fillers are re-orientated in thickness direction.

Skrabala, O.; Bonten, C.

2014-05-01

199

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

Science.gov (United States)

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. PMID:21277412

Lange, Ulrich; Mirsky, Vladimir M

2011-02-21

200

Sprayable electrically conductive polymer concrete coatings. Final report  

Energy Technology Data Exchange (ETDEWEB)

A sprayable electrically conductive polymer concrete coating for vertical and overhead applications has been developed. This technology, in conjunction with impressed current cathodic protection, can be used to prevent corrosion of the embedded reinforcing steel in concrete girders, piers, columns, and beams. A formulation of an electrically conductive polymer concrete, which holds the conductive filler in suspension and can be sprayed in thin uniform coatings, was developed. This coating is permeable, yet has low electrical resistivity, (<10 ohm-cm) good bond strength to concrete substrates, and good weatherability. The commercially available spray equipment can be used to spray mixtures containing up to 60 wt % calcined coke breeze and 40 wt % resin on vertical or overhead surfaces.

Fontana, J.J.; Reams, W.; Elling, D.

1985-06-01

 
 
 
 
201

Hybrid proton-conducting membranes for polymer electrolyte fuel cells  

Energy Technology Data Exchange (ETDEWEB)

The synthesis and characterization of a novel hybrid organic-inorganic material formed by phosphomolybdic acid H{sub 3}PMo{sub 12}O{sub 40} (PMo{sub 12}) and poly(2,5-benzimidazole) (ABPBI) is reported. This material, composed of two proton-conducting components, can be cast in the form of membranes from methanesulfonic acid (MSA) solutions. Upon impregnation with phosphoric acid, the hybrid membranes present higher conductivity than the best ABPBI polymer membranes impregnated in the same conditions. These electrolyte membranes are stable up to 200 deg. C, and have a proton conductivity of 3 x 10{sup -2} S cm{sup -1} at 185 deg. C without humidification. These properties make them very good candidates as membranes for polymer electrolyte membrane fuel cells (PEMFC) at temperatures of 100-200 deg. C.

Gomez-Romero, Pedro [Institut de Ciencia de Materials de Barcelona (CSIC), Campus UAB, E-08193 Bellaterra (Barcelona) (Spain)]. E-mail: pedro.gomez@icmab.es; Asensio, Juan Antonio [Institut de Ciencia de Materials de Barcelona (CSIC), Campus UAB, E-08193 Bellaterra (Barcelona) (Spain); Institut Quimic de Sarria, Universitat Ramon Llull, Via Augusta 390, E-08017 Barcelona (Spain); Borros, Salvador [Institut Quimic de Sarria, Universitat Ramon Llull, Via Augusta 390, E-08017 Barcelona (Spain)

2005-08-30

202

Hybrid proton-conducting membranes for polymer electrolyte fuel cells  

International Nuclear Information System (INIS)

The synthesis and characterization of a novel hybrid organic-inorganic material formed by phosphomolybdic acid H3PMo12O40 (PMo12) and poly(2,5-benzimidazole) (ABPBI) is reported. This material, composed of two proton-conducting components, can be cast in the form of membranes from methanesulfonic acid (MSA) solutions. Upon impregnation with phosphoric acid, the hybrid membranes present higher conductivity than the best ABPBI polymer membranes impregnated in the same conditions. These electrolyte membranes are stable up to 200 deg. C, and have a proton conductivity of 3 x 10-2 S cm-1 at 185 deg. C without humidification. These properties make them very good candidates as membranes for polymer electrolyte membrane fuel cells (PEMFC) at temperatures of 100-200 deg. C

2005-08-30

203

Conductive polymer PEDOT/PSS electrodes on the piezoelectric polymer PVDF  

Science.gov (United States)

Inkjet printing of conductive polymers has been successfully done before, but never before has the process been used to electrode piezoelectric polymers as we have done. Piezoelectric polymers such as poly(vinylidene fluoride) (PVDF) rely on high electric fields to take advantage of their mechanical output. The electrodes need to be securely attached to the PVDF and are traditionally made of metal. The rigidity of metal significantly reduces the performance of devices made with PVDF. We have applied much more flexible conductive polymer PEDOT/PSS (3,4-polyethylenedioxythiophene-polystyrenesulfonate) electrodes on PVDF using an HP 5850 inkjet printer. The inkjet printing method is simple and cost effective. It deposits the PEDOT/PSS in uniform coatings and allows for the creation of any desired patterns on the surface of the PVDF. We have also constructed bimorphs and actuators using PVDF with the new electrodes.

Polasik, Joseph T.; Schmidt, V. Hugo

2005-05-01

204

Thiophene in Conducting Polymers: Synthesis of Poly(thiophene)s and Other Conjugated Polymers Containing Thiophenes, for Application in Polymer Solar Cells  

DEFF Research Database (Denmark)

Conducting polymers based on thiophene are described. The polymers include poly(thiophene) with and without side-chains and other conjugated polymers in general, based on thiophene. The synthesis and characteristics of the polymers are described along with the application of these as light-absorbing materials in polymer solar cells.

Livi, Francesco; Carlé, Jon Eggert

2014-01-01

205

Electrically conductive, optically transparent polymer/carbon nanotube composites  

Science.gov (United States)

The present invention is directed to the effective dispersion of carbon nanotubes (CNTs) into polymer matrices. The nanocomposites are prepared using polymer matrices and exhibit a unique combination of properties, most notably, high retention of optical transparency in the visible range (i.e., 400-800 nm), electrical conductivity, and high thermal stability. By appropriate selection of the matrix resin, additional properties such as vacuum ultraviolet radiation resistance, atomic oxygen resistance, high glass transition (T.sub.g) temperatures, and excellent toughness can be attained. The resulting nanocomposites can be used to fabricate or formulate a variety of articles such as coatings on a variety of substrates, films, foams, fibers, threads, adhesives and fiber coated prepreg. The properties of the nanocomposites can be adjusted by selection of the polymer matrix and CNT to fabricate articles that possess high optical transparency and antistatic behavior.

Connell, John W. (Inventor); Smith, Jr., Joseph G. (Inventor); Harrison, Joycelyn S. (Inventor); Park, Cheol (Inventor); Watson, Kent A. (Inventor); Ounaies, Zoubeida (Inventor)

2011-01-01

206

Laser properties of luminescent conducting polymers in open resonators  

Science.gov (United States)

We have investigated the lasing properties of several luminescent conducting polymers, i.e. DOO-PPV and the bi- substituted polyacetylenes PDPA-nBu, and PHxPA, dissolved in various polar and non-polar solvents. PPV polymers emit with high quantum efficiencies in broad emission bands cantered in the orange/red region of the spectrum, depending on the solvent, and the PDPA polymers emit in the blue/green region. Our tested laser resonators include polymer solutions excited with 100 ps pulses from a regeneratively amplified mode-locked Nd:YAG laser. We obtain pulsed, low-threshold laser operation with repetition rate of up to 1 kHz. Resulting mainly from recent reported originally in the literature. The dependencies of threshold pump energy and output versus input power characteristics on material parameters are investigated for a fixed optical gain length. The results are compared with the standard Rhodamine 590 organic dye system used in the same wavelength regions. We have observed that the well know phenomenon of 'concentration quenching' in dye molecules does not happen in polymers. Spectral narrowing in PDPA-nBu solution, emitting near 500 nm, is also obtained for the first time.

Eradat Oskouei, Nayer; Gellermann, Werner; Shkunov, Maxim N.; Frolov, Sergey V.; Osaki, M.; Yoshino, Katsumi; Vardeny, Z. Valy

1997-12-01

207

Conductivity Enhancement of Polymer-Ceramic Nanoparticle Composite Electrolytes  

Science.gov (United States)

Polymer electrolytes have many advantages for high energy density, rechargeable lithium batteries including low density, ease of manufacture, and ability to accommodate volume changes. Incorporation of ceramic nanoparticles in a poly(ethylene oxide) matrix leads to increased conductivity, lithium ion transport number, and electrode-electrolyte interfacial stability. In order to elucidate the conductivity enhancement mechanism, the composite system has been studied by IR, DSC, and the effect upon conductivity of temperature, thermalization parameters, ceramic particle size and dielectric constant, DC field, and mechanical stretching. The polymer and ceramic phases interact to form a stable, amorphous state. The inclusion of the ceramic phase appears to have a dual effect: the suppression of crystallization and an additional interaction with the polymer phase, believed to be dipolar in nature. At low temperatures(about 20°C) the dipole-dipole interaction is favored, whereas at high temperatures(about 100°C) a reverse trend is observed. Models shall be presented for the dipolar interaction and the resultant conductivity enhancement.

Kumar, B.; Rodrigues, S. J.; Scanlon, L. G.; Spry, R. J.

2002-03-01

208

Luminescence study of SHI irradiated nano semiconductor: Conducting polymer composite  

Energy Technology Data Exchange (ETDEWEB)

Semiconductor nanoparticle and conducting polymer composite is an interesting class of materials for optoelectronic and photovoltaic device application. We have synthesized a composite of nanocrystalline PbS and conducting polymer MEH-PPV by chemical synthesis and studied the effect of swift heavy ion (SHI) irradiation on the composite material. The irradiation of the composite materials in thin film form is carried out with 120 MeV Si{sup +9} ion beam at fluences from 5x10{sup 10} to 10{sup 13} ions/cm{sup 2}. Fluence dependent optical and structural properties have been observed in optical absorption, PL and TEM studies. Reduction of nanoparticle size has been observed after irradiation.

Chowdhury, S., E-mail: shyamoli_ma@yahoo.co.i [Department of Physics, Gauhati University, Guwahati, Assam 781 014 (India); Hussain, A.M.P. [Institute of Physics, Sachivalaya Marg, Bhubaneswar 751005 (India); Ahmed, G.A. [Department of Physics, Tezpur University, Napaam, Tezpur, Assam 784 028 (India); Singh, F.; Avasthi, D.K. [Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110 067 (India); Choudhury, A. [Department of Physics, Tezpur University, Napaam, Tezpur, Assam 784 028 (India)

2010-02-15

209

New conducting polymers/carbon composite materials for energy storage  

Energy Technology Data Exchange (ETDEWEB)

This paper describes the combination of the complementary properties of electronically conducting polymers (ECPs) with effective conductive materials such as thermally exfoliated graphite (TEG) from Superior Graphite Co. (SGC) in Chicago, United States, and multi walled carbon nanotubes (MWCN) from CMRD, CNRS-University in France. The objective was to improve the electrochemical characteristics of electrodes based on ECPs for energy storage. Scanning and transmission electron microscopy were used to determine the structural characterization of nano-composites. The results showed that a homogeneous layer of ECP has been deposited on the multi-walled nano tubes (MWNTs). When the percentage of ECP was greater than 60 per cent, the behaviour of the nano-composites was similar. At low degrees of ECPs oxidation, the faradaic process applies, and at higher degrees, involved charges transforms ECPs in a metal-like state. These polymer materials are interesting for application in electrochemical capacitors. 2 refs., 1 tab.

Khomenko, V. [Kiev National University of Technologies and Design, Kiev (Ukraine)]|[CNRS-University, Orleans (France). CRMD; Barsukov, V. [Kiev National University of Technologies and Design, Kiev (Ukraine); Frckowiak, E. [Poznan University of Technology, Poznan (Poland); Beguin, F. [CNRS-University, Orleans (France). CRMD

2003-07-01

210

Effective medium theory of conduction in stretched polymer electrolytes  

CERN Document Server

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

211

Conductivity of transparent indium-tin-oxidenanoparticle/polymer composite layers  

International Nuclear Information System (INIS)

The conductivity and optical absorption behavior of transparent composite layers consisting of conductive polymer poly(3,4ethylenedioxythiophene)/poly(4-styrene sulfonate) (PEDT:PSS) mixed with high conductive Indium Tin Oxide (ITO) nanoparticles was investigated. Below the percolation threshold of the ITO nanoparticles, at a volume fraction of the ITO ?0.16, the conductivity decreases with increase of the ITO content. The reason for this decrease is a compensation of charge carriers between the p-doped PEDT:PSS and the n-doped ITO. By applying a simple harmonic oscillator approximation, based on superposition of two phase system and a partial compensation of carriers the change in the optical characteristics can be explained. Furthermore, the reduction of the total numbers of charge carriers by compensation explains the decrease of conductivity

2007-03-26

212

Conduction mechanisms and charge storage in Si-nanocrystals metal-oxide-semiconductor memory devices studied with conducting atomic force microscopy  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this work, we demonstrate that conductive atomic force microscopy (C-AFM) is a very powerful tool to investigate, at the nanoscale, metal-oxide-semiconductor structures with silicon nanocrystals (Si-nc) embedded in the gate oxide as memory devices. The high lateral resolution of this technique allows us to study extremely small areas ( ~ 300nm2) and, therefore, the electrical properties of a reduced number of Si-nc. C-AFM experiments have demonstrated that Si-nc enhance the gate oxide elec...

2005-01-01

213

A facile biofunctionalisation route for solution processable conducting polymer devices  

Digital Repository Infrastructure Vision for European Research (DRIVER)

For the majority of biosensors or biomedical devices, immobilization of the biorecognition element is a critical step for device function. To achieve longer lifetime devices and controllable functionalization, covalent immobilisation techniques are preferred over passive adhesion and electrostatic interactions. The rapidly emerging field of organic bioelectronics uses conducting polymers (or small molecules) as the active materials for transduction of the biological signal to an electronic on...

2014-01-01

214

Stimulation of neurite outgrowth using an electrically conducting?polymer  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Damage to peripheral nerves often cannot be repaired by the juxtaposition of the severed nerve ends. Surgeons have typically used autologous nerve grafts, which have several drawbacks including the need for multiple surgical procedures and loss of function at the donor site. As an alternative, the use of nerve guidance channels to bridge the gap between severed nerve ends is being explored. In this paper, the electrically conductive polymer—oxidized polypyrrole (PP)—has been evaluated for...

Schmidt, Christine E.; Shastri, Venkatram R.; Vacanti, Joseph P.; Langer, Robert

1997-01-01

215

Na+ Ion Conducting Hot-pressed Nano Composite Polymer Electrolytes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 be...

Angesh Chandra; Archan Chandra; Kiran Thakurb

2012-01-01

216

Better Proton-Conducting Polymers for Fuel-Cell Membranes  

Science.gov (United States)

Polyoxyphenylene triazole sulfonic acid has been proposed as a basis for development of improved proton-conducting polymeric materials for solid-electrolyte membranes in hydrogen/air fuel cells. Heretofore, the proton-conducting membrane materials of choice have been exemplified by a family of perfluorosulfonic acid-based polymers (Nafion7 or equivalent). These materials are suitable for operation in the temperature of 75 to 85 C, but in order to reduce the sizes and/or increase the energy-conversion efficiencies of fuel-cell systems, it would be desirable to increase temperatures to as high as 120 C for transportation applications, and to as high as 180 C for stationary applications. However, at 120 C and at relative humidity values below 50 percent, the loss of water from perfluorosulfonic acid-based polymer membranes results in fuel-cell power densities too low to be of practical value. Therefore, membrane electrolyte materials that have usefully high proton conductivity in the temperature range of 180 C at low relative humidity and that do not rely on water for proton conduction at 180 C would be desirable. The proposed polyoxyphenylene triazole sulfonic acid-based materials have been conjectured to have these desirable properties. These materials would be free of volatile or mobile acid constituents. The generic molecular structure of these materials is intended to exploit the fact, demonstrated in previous research, that materials that contain ionizable acid and base groups covalently attached to thermally stable polymer backbones exhibit proton conduction even in the anhydrous state.

Narayan, Sri; Reddy, Prakash

2012-01-01

217

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.; Sommer-Larsen, P.

2006-01-01

218

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

International Nuclear Information System (INIS)

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

219

Conducting polymer nanofibers for high sensitivity detection of chemical analytes.  

Science.gov (United States)

Possessing large surface area materials is vital for high sensitivity detection of analyte. We report a novel, inexpensive and simple technique to make high surface area sensing interfaces using electrospinning. Conducting polymers (CP) nanotubes were made by electrospinning a solution of a catalyst (ferric tosylate) along with poly (lactic acid), which is an environment friendly biodegradable polymer. Further vapor deposition polymerization of the monomer ethylenedioxy thiophene (EDOT) on the nanofiber surface yielded poly (EDOT) covered fibers. X-ray photo electron spectroscopy (XPS) study reveals the presence of PEDOT predominantly on the surface of nanofibers. Conducting nanotubes had been received by dissolving the polymer in the fiber core. By a similar technique we had covalently incorporated fluorescent dyes on the nanofiber surface. The materials obtained show promise as efficient sensing elements. UV-Vis characterization confirms the formation of PEDOT nanotubes and incorporation of chromophores on the fiber surface. The morphological characterization was carried out using scanning electron microscopy (SEM) and transmission electron microscopy (TEM).

Kumar, Abhishek; Leshchiner, Ignaty; Nagarajan, Subhalakshmi; Nagarajan, Ramaswamy; Kumar, Jayant

2008-03-01

220

Synthesis and characterization of EDOT-based conducting polymer actuators  

Science.gov (United States)

Freestanding films of poly(3,4-ethylenedioxythiopene), PEDOT, were synthesized electrochemically from a solution containing EDOT monomer, tetrabutylammonium hexafluorophosphate, and water in propylene carbonate. The films were tested mechanically under constant stresses ranging from 0.6 to 2.1 MPa and subjected to various electrochemical waveforms while immersed in a bath containing propylene carbonate and an electrolyte. The characterization resulted in observations of ultimate linear strains of 2%, strain rates of 0.003 Hz, and strain to charge densities of 4 x 10-10 m3/C, comparable to the conventional conducting polymer polypyrrole. In addition to the quantitative analysis, evidence of both anionic and cationic intercalation into the polymer is presented with a discussion of prospective mechanisms and consequences.

Vandesteeg, Nathan; Madden, Peter G. A.; Madden, John D.; Anquetil, Patrick A.; Hunter, Ian W.

2003-07-01

 
 
 
 
221

Amplified resonant Raman scattering in conducting polymer thin films  

Energy Technology Data Exchange (ETDEWEB)

Using picosecond pulsed laser excitation, we investigate the optical emission characteristics of poly(2,5-dioctyloxy-{ital p}-phenylenevinylene), (DOO-PPV), thin films at high excitation intensities ({approximately}1{endash}90 MW/cm{sup 2}). We observe the presence of amplified resonance Raman scattering in the emission spectra of conducting polymer films. The effect results in sharp Raman lines (widths smaller than 3 {Angstrom}) superimposed on a significantly broader, well known, spectrally narrowed emission band (width {approximately}10 nm) caused by the amplified spontaneous emission in the waveguided polymer film. At the highest used excitation intensities, Raman scattering dominates the DOO-PPV emission spectrum resulting in a highly monochromatic, single-line emission spectrum. {copyright} {ital 1998 American Institute of Physics.}

Shkunov, M.N.; Gellermann, W.; Vardeny, Z.V. [University of Utah, Department of Physics, Salt Lake City, Utah 84112 (United States)

1998-11-01

222

Amplified resonant Raman scattering in conducting polymer thin films  

Science.gov (United States)

Using picosecond pulsed laser excitation, we investigate the optical emission characteristics of poly(2,5-dioctyloxy-p-phenylenevinylene), (DOO-PPV), thin films at high excitation intensities (~1-90 MW/cm2). We observe the presence of amplified resonance Raman scattering in the emission spectra of conducting polymer films. The effect results in sharp Raman lines (widths smaller than 3 Å) superimposed on a significantly broader, well known, spectrally narrowed emission band (width ~10 nm) caused by the amplified spontaneous emission in the waveguided polymer film. At the highest used excitation intensities, Raman scattering dominates the DOO-PPV emission spectrum resulting in a highly monochromatic, single-line emission spectrum.

Shkunov, M. N.; Gellermann, W.; Vardeny, Z. V.

1998-11-01

223

Conductivity enhancement in polymer electrolytes on gamma irradiation  

International Nuclear Information System (INIS)

We expose PEO(1-x)-NH4ClO4(x) (with x = 0.16-0.26) to gamma irradiation with doses varying from 10 to 40 kGy. The change in ion-conductivity with irradiation is observed. The ion-conductivity goes through a maximum at 30 kGy. The enhancement is two orders of magnitude for the x=0.16 sample, but not significant for x higher than 0.20. An equivalent circuit is used to fit simultaneously the Cole-Cole plot and the real part of admittance vs. frequency plot. It is seen that the samples show an inductive loop at high frequency for low doses, where conductivity is low. This may be a result of the spiral coiling of the polymer molecules.

2011-01-01

224

Conductivity enhancement in polymer electrolytes on gamma irradiation  

Energy Technology Data Exchange (ETDEWEB)

We expose PEO(1-x)-NH{sub 4}ClO{sub 4}(x) (with x = 0.16-0.26) to gamma irradiation with doses varying from 10 to 40 kGy. The change in ion-conductivity with irradiation is observed. The ion-conductivity goes through a maximum at 30 kGy. The enhancement is two orders of magnitude for the x=0.16 sample, but not significant for x higher than 0.20. An equivalent circuit is used to fit simultaneously the Cole-Cole plot and the real part of admittance vs. frequency plot. It is seen that the samples show an inductive loop at high frequency for low doses, where conductivity is low. This may be a result of the spiral coiling of the polymer molecules.

Nanda, Pradyot; Maity, Sankar [Condensed Matter Physics Research Centre, Physics Department, Jadavpur University, Kolkata 700032 (India); Pandey, Namita [Department of Physics and Meteorology, IIT Kharagpur, Kharagpur 721302 (India); Ray, Ruma [Physics Department, Gurudas College, Kolkata 700054 (India); Thakur, A.K. [Department of Physics and Meteorology, IIT Kharagpur, Kharagpur 721302 (India); Tarafdar, Sujata, E-mail: sujata_tarafdar@hotmail.co [Condensed Matter Physics Research Centre, Physics Department, Jadavpur University, Kolkata 700032 (India)

2011-01-15

225

Multi-component single-substrate conducting polymer actuation systems and fabrication techniques  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Conducting polymer materials can be employed as actuation elements, length sensors, force sensors, energy storage devices, and electrical components. Combining the various functionalities of conducting polymers to create singlesubstrate, integrated systems remains a challenge, as chemical and electrical insulation barriers, adhesion techniques, and the possibility of scaling need to be taken into consideration. Here fabrication techniques for combining multiple conducting polymer components b...

2011-01-01

226

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

227

Current passage tubes in conductive polymer composite for fluid heating  

International Nuclear Information System (INIS)

This communication reports the design and testing of a tubular heat exchanger in conductive polymer composites (CPC) using the ohmic effect (current passage tube). The weak inertia and the good thermal efficiencies of such a device are fully suitable for water or thermo-sensitive products heating. The materials of the extruded tubes are obtained by blending an insulating thermoplastic polymer matrix with a conductive filler like carbon black nano particles. The electrical resistivity of the composite can be adjusted by the nature and content of the filler. Consequently, an electrical transformer is no longer needed for the electrical input of the heat exchanger. The results presented deal with two different poly(propylene) tubes. The first one is filled with carbon black only, whereas short carbon fibres are added in the second one. First, the effect of the filler content on the electrical and thermal conductivities is quantified. Then, the coupling of the electrical and thermal phenomena is studied. Experimental tests, performed with and without water flow inside the tubes, were completed on a device developed in our laboratory. These experiments were performed under direct current to show the thermal and electrical behaviours of the tubes. The numerical simulation of the temperature profile in the thickness of the pipes corresponds well with the experimental results

2008-04-01

228

Supercapacitors based on conducting polymers/nanotubes composites  

Science.gov (United States)

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

Frackowiak, E.; Khomenko, V.; Jurewicz, K.; Lota, K.; Béguin, F.

229

Synthesis and Characterization of Novel Organic Conducting Polymers  

Canada Institute for Scientific and Technical Information (Canada)

The last two years have seen an extraordinary growth of interest in photovoltaic (PV) cells made from organic conducting polymers. Such attention stems primarily from the prospect of using organic materials in manufacturing ultra thin, flexible devices. Polymeric photovoltaic cells also present a tantalizing possibility for producing coatings that function as sunlight-harvesting paints or even for developing fabrics to produce electricity from sunlight. The U.S. Navy developed an interest in electroactive polymeric research because of these specific potential applications for such devices and the materials from which they are based. The Office of Naval Research is currently probing new opportunities to convert energy into useful power sources, motivated by its interest in the development of an electric Navy for future years. The technical objectives for this Trident Scholar project were the synthesis and characterization of high conductivity, high optical transparency conducting polymer films that incorporate 3,4-ethylenedixoythiophene (EDOT) monomers. Initially, the EDOT derivative 2,3-dihydrothieno3,4-B1,4dioxin-2-yl methanol was synthesized via a multi-step process starting from diethyl 3,4-dihydroxythiophene-2,5-dicarboxylate. Triphenylamine and oligo(p-phenylene vinylene) units were also synthesized to be employed as light-harvesting groups.

2004-01-01

230

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

231

Utilization of novel bithiazole based conducting polymers in electrochromic applications  

International Nuclear Information System (INIS)

In this paper we disclose the synthesis of a novel monomer (2,2?-di-pyrrol-1-yl-[4,4?]bithiazolyl, PyDBTH) and the optoelectronic properties of the resultant conducting polymers. PyDBTH was synthesized via the Clauson-Kaas reaction of 2,2?-diamino-4,4?-bithiazole with 2,5-dimethoxytetrahydrofuran in acetic acid which was characterized by 1H, 13C-NMR, FTIR and MS analyses. Homopolymerization and copolymerization (in the presence of 3,4-ethylenedioxythiophene) were achieved in a tetrabutylammonium hexafluorophosphate (TBAPF6) dichloromethane system. The electrochemical and electrochromic properties of the homopolymer and copolymers were examined by cyclic voltammetry, FTIR, spectroelectrochemistry and kinetic studies. Depending on the synthesis conditions, the bithiazole based polymers exhibited optical band gaps ranging from 2.60 to 1.75 eV and the copolymers displayed multichromism within a wide span of the visible spectrum. The copolymers revealed short switching times and useful optical contrast of 0.6 s and 54%, respectively. Due to its favorable electrochromic properties, utilization of bithiazole based polymers in electrochromic devices was also investigated. These devices exhibited low switching voltages and switching times with reasonable stability under atmospheric conditions. (paper)

2012-02-01

232

Synthesis and electrically conductive polymer/inorganic composites: In situ oxidative polymerization/intercalation of conducting polymers in layered hosts  

Energy Technology Data Exchange (ETDEWEB)

The redox intercalation of polyaniline, polypyrrole and polythiophene in V[sub 2]O[sub 5] xerogel is a topotactic reaction which was achieved by reacting aniline, pyrrole and 2,2'-bithiophene with V[sub 2]O[sub 5] xerogel. Upon intercalation, the interlayer spacing expanding from 11.55 [angstrom] to 13.94 [angstrom], 15.20 [angstrom] and 14.70[degrees] for polyaniline/V[sub 2]O[sub 5] polypyrrole/V[sub 2]O[sub 5] and polythiophene/V[sub 2]O[sub 5] respectively. The room temperature conductivity of polymer/V[sub 2]O[sub 5] composites is in the range of 10[sup [minus]4] [approximately] 10[sup 0][Omega][sup [minus]1]cm[sup [minus]1] and decreases with temperature. The charge transport properties of these composities vary significantly from each other. They can be semiconductors or metal-like, with n-type or p-type conductivity depending on the reaction media, polymer/V[sub 2]O[sub 5] ratio and polymer molecular weight. Upon standing in air, the magnetic moment of all polymer/V[sub 2]O[sub 5] composites decreases. Another effect oxygen has on (PANI)[sub x]V[sub 2]O[sub 5]nH[sub 2]O is to cause the intercalated polyaniline chains to oxidatively polymerize to form longer chains. This increased the conductivity. (PANI)[sub x]FeOCl was obtained by reacting FeOCl with excess aniline in acetonitrile at room temperature. The products have interlayer spacing equal to 13.96 [angstrom]. The thermoelectric power of all samples shows p-type semiconductor behavior. Upon sitting in air (aging), two separate processes occurred: the FeOCl is hydrolyzed to [beta]-FeO OH, and polyaniline chains continue to oxidatively polymerize forming longer chains of polymer. Intercalation of polyfuran was achieved by taking advantage of the lower oxidation potentials of terfuran and quaterfuran. Two different products were isolated depending on the reaction conditions. Variable temperature thermopower data of both products show typical p-type semiconductor behavior similar to (PANI)[sub x]FeOCl.

Wu, C.G.

1992-01-01

233

Electrical Conductivity in Polymer Blends/ Multiwall Carbon Nanotubes  

International Nuclear Information System (INIS)

Carbon nanotubes (CNT) based polymer composites have emerged as the future multifunctional materials in view of its exceptional mechanical, thermal and electrical properties. One of the major interests is to develop conductive polymer composites preferably at low concentration of CNT utilizing their high aspect ratio (L/D) for numerous applications, which include antistatic devices, capacitors and materials for EMI shielding. In this context, polymer blends have emerged as a potential candidate in lowering the percolation thresholds further by the utilization of 'double-percolation' which arises from the synergistic improvements in blend properties associated with the co-continuous morphology. Due to strong inter-tube van der Waals' forces, they often tend to aggregate and uniform dispersion remains a challenge. To overcome this challenge, we exploited sodium salt of 6-aminohexanoic acid (Na-AHA) which was able to assist in debundlling the multiwall carbon nanotubes (MWNT) through 'cation-?' interactions during melt-mixing leading to percolative 'network-like' structure of MWNT within polyamide6 (PA6) phase in co-continuous PA6/acrylonitrile butadiene styrene (ABS) blends. The composite exhibited low electrical percolation thresholds of 0.25 wt% of MWNT, the lowest reported value in this system so far. Retention of 'network-like structure' in the solid state with significant refinement was observed even at lower MWNT concentration in presence Na-AHA, which was assessed through AC electrical conductivity measurements. Reactive coupling was found to be a dominant factor besides 'cation-?' interactions in achieving low electrical percolation in PA6/ABS+MWNT composites.

2008-10-23

234

Multiscale Modeling of Thermal Conductivity of Polymer/Carbon Nanocomposites  

Science.gov (United States)

Molecular dynamics simulation was used to estimate the interfacial thermal (Kapitza) resistance between nanoparticles and amorphous and crystalline polymer matrices. Bulk thermal conductivities of the nanocomposites were then estimated using an established effective medium approach. To study functionalization, oligomeric ethylene-vinyl alcohol copolymers were chemically bonded to a single wall carbon nanotube. The results, in a poly(ethylene-vinyl acetate) matrix, are similar to those obtained previously for grafted linear hydrocarbon chains. To study the effect of noncovalent functionalization, two types of polyethylene matrices. -- aligned (extended-chain crystalline) vs. amorphous (random coils) were modeled. Both matrices produced the same interfacial thermal resistance values. Finally, functionalization of edges and faces of plate-like graphite nanoparticles was found to be only modestly effective in reducing the interfacial thermal resistance and improving the composite thermal conductivity

Clancy, Thomas C.; Frankland, Sarah-Jane V.; Hinkley, Jeffrey A.; Gates, Thomas S.

2010-01-01

235

Proton-conducting polymer electrolytes based on methacrylates  

International Nuclear Information System (INIS)

Proton-conducting polymer electrolytes based on methacrylates were prepared by direct, radical polymerization of ethyl (EMA), 2-ethoxyethyl (EOEMA), and 2-hydroxyethyl methacrylate (HEMA). Samples with embedded solutions of phosphoric acid in propylene carbonate (PC), ?-butyrolactone (GBL), N,N-dimethylformamide (DMF) and their mixtures were studied using impedance, voltammetrical and thermogravimetric methods. Membranes of long-term stability exhibit ionic conductivity up to 6.7 x 10-5 S cm-1 at 25 deg. C reached for the sample PEMA-PC-H3PO4 (31:42:27 mol.%). The accessible electrochemical potential window is 2.2-3 V depending on the working electrode material (glassy carbon or platinum). The thermogravimetric analysis shows that the membranes are thermally stable up to 110-130 deg. C

2008-11-01

236

Proton-conducting polymer electrolytes based on methacrylates  

Energy Technology Data Exchange (ETDEWEB)

Proton-conducting polymer electrolytes based on methacrylates were prepared by direct, radical polymerization of ethyl (EMA), 2-ethoxyethyl (EOEMA), and 2-hydroxyethyl methacrylate (HEMA). Samples with embedded solutions of phosphoric acid in propylene carbonate (PC), {gamma}-butyrolactone (GBL), N,N-dimethylformamide (DMF) and their mixtures were studied using impedance, voltammetrical and thermogravimetric methods. Membranes of long-term stability exhibit ionic conductivity up to 6.7 x 10{sup -5} S cm{sup -1} at 25 C reached for the sample PEMA-PC-H{sub 3}PO{sub 4} (31:42:27 mol.%). The accessible electrochemical potential window is 2.2-3 V depending on the working electrode material (glassy carbon or platinum). The thermogravimetric analysis shows that the membranes are thermally stable up to 110-130 C. (author)

Reiter, Jakub [Institute of Inorganic Chemistry of the ASCR, v. v. i., 250 68 Rez near Prague (Czech Republic); Velicka, Jana; Mika, Martin [Institute of Chemical Technology Prague, 166 28 Prague 6 (Czech Republic)

2008-11-01

237

Rechargeable aluminum batteries with conducting polymers as positive electrodes.  

Energy Technology Data Exchange (ETDEWEB)

This report is a summary of research results from an Early Career LDRD project con-ducted from January 2012 to December 2013 at Sandia National Laboratories. Demonstrated here is the use of conducting polymers as active materials in the posi-tive electrodes of rechargeable aluminum-based batteries operating at room tempera-ture. The battery chemistry is based on chloroaluminate ionic liquid electrolytes, which allow reversible stripping and plating of aluminum metal at the negative elec-trode. Characterization of electrochemically synthesized polypyrrole films revealed doping of the polymers with chloroaluminate anions, which is a quasi-reversible reac-tion that facilitates battery cycling. Stable galvanostatic cycling of polypyrrole and polythiophene cells was demonstrated, with capacities at near-theoretical levels (30-100 mAh g-1) and coulombic efficiencies approaching 100%. The energy density of a sealed sandwich-type cell with polythiophene at the positive electrode was estimated as 44 Wh kg-1, which is competitive with state-of-the-art battery chemistries for grid-scale energy storage.

Hudak, Nicholas S.

2013-12-01

238

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

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

2009-01-01

239

Conductivity enhancement of conjugated polymer after HCl-methanol treatment  

Energy Technology Data Exchange (ETDEWEB)

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{sup -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.

Kang, K.S., E-mail: kkang@inha.ac.k [Creative Research Center for Electroactive Paper (EAPap) Actuator, Mechanical Engineering Department, Inha University, 253 Yonghyun-Dong Nam-Ku, Incheon, 402-751 (Korea, Republic of); Chen, Y.; Han, K.J.; Yoo, K.H.; Kim, J. [Creative Research Center for Electroactive Paper (EAPap) Actuator, Mechanical Engineering Department, Inha University, 253 Yonghyun-Dong Nam-Ku, Incheon, 402-751 (Korea, Republic of)

2009-08-31

240

Conductivity enhancement of conjugated polymer after HCl-methanol treatment  

International Nuclear Information System (INIS)

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

 
 
 
 
241

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 poly...

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

2013-01-01

242

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

243

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

244

Polymerization of the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) around living neural cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this paper we describe interactions between neural cells and the conducting polymer poly(3,4-ethylenedioxythiophene (PEDOT) toward development of electrically conductive biomaterials intended for direct, functional contact with electrically-active tissues such as the nervous system, heart, and skeletal muscle. We introduce a process for polymerizing PEDOT around living cells and describe a neural cell-templated conducting polymer coating for microelectrodes and a hybrid conducting polymer-...

Richardson-burns, Sarah M.; Hendricks, Jeffrey L.; Foster, Brian; Povlich, Laura K.; Kim, Dong-hwan; Martin, David C.

2007-01-01

245

Quantum soliton conductivity in polymers: a field theory approach  

International Nuclear Information System (INIS)

Full text: The discovery of a tremendous increase in the electrical conductivity of polyacetylene, the simplest linear conjugated polymer, when doped with either halogens or alkalis, was a breakthrough of far reaching consequences in physics and chemistry. The fact that the trans-isomer occurs in two degenerate species opens the possibility of occurrence of soliton defects interconnecting them. Indeed, quantum solitons or polarons are supposed to play a crucial role in the electric conductivity of polyacetylene, in the intermediate doping regime. In this work, we present an exact fully quantized calculation of the quantum soliton conductivity in polyacetylene and show that it vanishes exactly. This strongly suggests that dynamic solitons are not the charge carriers in polyacetylene. Rather, polarons, which are basically soliton-anti soliton bound states should be responsible for the transport of charge in the intermediate doping regime of polyacetylene. This result is obtained by applying a general method of soliton quantization, based on order-disorder duality, to a Z(2)-symmetric complex extension of the TLM (Takayama, Lin-Liu and Maki) dimerization effective field theory. We show that, in this theory, polyacetylene solitons are sine-Gordon solitons in the phase of the complex field. (author)

2011-06-05

246

Ion beam effects on electrical characteristics of proton conductive polymer  

Energy Technology Data Exchange (ETDEWEB)

Effect of MeV ion irradiation on the perfluorosulphonic polymer membrane was studied concerning with electrical characteristics. The DC electrical conductivity in dry condition increased of three orders of magnitude as a consequence of irradiation with MeV H and He ion beam at a fluence of 2 x 10{sup 13} ions/cm{sup 2}. The ion induced improvement of the conductivity was independent of the penetrating depth of the ions. The electron and gamma-ray irradiation showed similar enhancement of the conductivity when the same energy was deposited in the membrane. The optical absorption in the ultra-violet region increased in the ion irradiated membrane due to the formation of fluorocarbon and peroxy radicals, while the up-take of the water molecules were not found by the absorption in the infrared region. The ion irradiation may promote the dissociation of the water molecules at the surface and also improve the transport property of protons in the membrane.

Nagata, S. [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan)]. E-mail: nagata@imr.tohoku.ac.jp; Konishi, Y. [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Tsuchiya, B. [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Toh, K. [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Yamamoto, S. [Japan Atomic Energy Agency, Takasak 270-1292 (Japan); Takahiro, K. [Department of Chemistry and Materials Technology, Kyoto Institute of Technology, Kyoto 606-8585 (Japan); Shikama, T. [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan)

2007-04-15

247

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

Science.gov (United States)

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.

2009-01-01

248

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

2009-01-01

249

A New Conducting Polymer Electrode for Organic Electroluminescence Devices  

International Nuclear Information System (INIS)

Conducting polymer polydimethylsiloxane (PDMS) is studied for the high performance electrode of organic electroluminescence devices. A method to prepare the electrode consisting of a SiC thin film and PDMS is investigated. By using ultra thin SiC films with different thicknesses, the organic electroluminescence devices are obtained in an ultra vacuum system with the model device PDMS/SiC/PPV/Alq3, where PPV is poly para-phenylene vinylene and Alq3 is tris(8-hydroxyquinoline) aluminium. The capacitance-voltage (C - V), capacitance-frequency (C - F), current-voltage (I - V), radiation intensity-voltage (R - V) and luminance efficiency-voltage (E - V) measurements are systematically studied to investigate the conductivity, Fermi alignment and devices properties in organic semiconductors. Scanning Kelvin probe measurement shows that the work function ofPDMS/SiC anode with a 2.5-nm SiC over layer can be increased by as much as 0.28 eV, compared to the conventional ITO anode. The result is attributed to the charge transfer effect and ohmic contacts at the interface. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

2008-08-01

250

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

251

Soft capacitor fibers using conductive polymers for electronic textiles  

International Nuclear Information System (INIS)

A novel, highly flexible, conductive polymer-based fiber with high electric capacitance is reported. In its cross section the fiber features a periodic sequence of hundreds of conductive and isolating plastic layers positioned around metallic electrodes. The fiber is fabricated using the fiber drawing method, where a multi-material macroscopic preform is drawn into a sub-millimeter capacitor fiber in a single fabrication step. Several kilometers of fibers can be obtained from a single preform with fiber diameters ranging between 500 and 1000 µm. A typical measured capacitance of our fibers is 60–100 nF m?1 and it is independent of the fiber diameter. Analysis of the fiber frequency response shows that in its simplest interrogation mode the capacitor fiber has a transverse resistance of 5 k? m L?1, which is inversely proportional to the fiber length L and is independent of the fiber diameter. Softness of the fiber materials, the absence of liquid electrolyte in the fiber structure, ease of scalability to large production volumes and high capacitance of our fibers make them interesting for various smart textile applications ranging from distributed sensing to energy storage

2010-11-01

252

Stimulation of neurite outgrowth using an electrically conducting polymer.  

Science.gov (United States)

Damage to peripheral nerves often cannot be repaired by the juxtaposition of the severed nerve ends. Surgeons have typically used autologous nerve grafts, which have several drawbacks including the need for multiple surgical procedures and loss of function at the donor site. As an alternative, the use of nerve guidance channels to bridge the gap between severed nerve ends is being explored. In this paper, the electrically conductive polymer--oxidized polypyrrole (PP)--has been evaluated for use as a substrate to enhance nerve cell interactions in culture as a first step toward potentially using such polymers to stimulate in vivo nerve regeneration. Image analysis demonstrates that PC-12 cells and primary chicken sciatic nerve explants attached and extended neurites equally well on both PP films and tissue culture polystyrene in the absence of electrical stimulation. In contrast, PC-12 cells interacted poorly with indium tin oxide (ITO), poly(L-lactic acid) (PLA), and poly(lactic acid-co-glycolic acid) surfaces. However, PC-12 cells cultured on PP films and subjected to an electrical stimulus through the film showed a significant increase in neurite lengths compared with ones that were not subjected to electrical stimulation through the film and tissue culture polystyrene controls. The median neurite length for PC-12 cells grown on PP and subjected to an electrical stimulus was 18.14 micron (n = 5643) compared with 9.5 micron (n = 4440) for controls. Furthermore, animal implantation studies reveal that PP invokes little adverse tissue response compared with poly(lactic acid-co-glycolic acid). PMID:9256415

Schmidt, C E; Shastri, V R; Vacanti, J P; Langer, R

1997-08-19

253

Stimulation of neurite outgrowth using an electrically conducting polymer  

Science.gov (United States)

Damage to peripheral nerves often cannot be repaired by the juxtaposition of the severed nerve ends. Surgeons have typically used autologous nerve grafts, which have several drawbacks including the need for multiple surgical procedures and loss of function at the donor site. As an alternative, the use of nerve guidance channels to bridge the gap between severed nerve ends is being explored. In this paper, the electrically conductive polymer—oxidized polypyrrole (PP)—has been evaluated for use as a substrate to enhance nerve cell interactions in culture as a first step toward potentially using such polymers to stimulate in vivo nerve regeneration. Image analysis demonstrates that PC-12 cells and primary chicken sciatic nerve explants attached and extended neurites equally well on both PP films and tissue culture polystyrene in the absence of electrical stimulation. In contrast, PC-12 cells interacted poorly with indium tin oxide (ITO), poly(l-lactic acid) (PLA), and poly(lactic acid-co-glycolic acid) surfaces. However, PC-12 cells cultured on PP films and subjected to an electrical stimulus through the film showed a significant increase in neurite lengths compared with ones that were not subjected to electrical stimulation through the film and tissue culture polystyrene controls. The median neurite length for PC-12 cells grown on PP and subjected to an electrical stimulus was 18.14 ?m (n = 5643) compared with 9.5 ?m (n = 4440) for controls. Furthermore, animal implantation studies reveal that PP invokes little adverse tissue response compared with poly(lactic acid-co-glycolic acid).

Schmidt, Christine E.; Shastri, Venkatram R.; Vacanti, Joseph P.; Langer, Robert

1997-01-01

254

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

255

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 reinf...

Kyriaki Kalaitzidou; Hiroyuki Fukushima; Drzal, Lawrence T.

2010-01-01

256

Polymer coated inorganic nanoparticles: tailoring the nanocrystal surface for designing nanoprobes with biological implications  

Science.gov (United States)

The use of inorganic nanoparticles in biomedicine, in particular in the field of diagnosis and therapy of human diseases, has rapidly grown in the last few decades. Water solubilisation of the nanoparticles, especially for particles synthesized in non-polar solvents, is an essential prerequisite for their biological exploitation. The encapsulation of surfactant coated nanoparticles into polymer shells represents one of the most suitable and most popular methods to make them water soluble. Herein we provide an overview of the amphiphilic polymer molecules used and the efforts undertaken to further tailor the surface of polymer coated nanoparticles with fluorescent dyes, chemical sensor molecules and small or large biomolecules for the preparation of bio-functional nanoprobes. Their biological implications, highlighting limitations and challenges, are also discussed.The use of inorganic nanoparticles in biomedicine, in particular in the field of diagnosis and therapy of human diseases, has rapidly grown in the last few decades. Water solubilisation of the nanoparticles, especially for particles synthesized in non-polar solvents, is an essential prerequisite for their biological exploitation. The encapsulation of surfactant coated nanoparticles into polymer shells represents one of the most suitable and most popular methods to make them water soluble. Herein we provide an overview of the amphiphilic polymer molecules used and the efforts undertaken to further tailor the surface of polymer coated nanoparticles with fluorescent dyes, chemical sensor molecules and small or large biomolecules for the preparation of bio-functional nanoprobes. Their biological implications, highlighting limitations and challenges, are also discussed. Electronic supplementary information (ESI) available: Experimental section and additional details on structural characterization of the various nanoparticles functionalized conjugates are included. See DOI: 10.1039/c2nr30271c

Quarta, Alessandra; Curcio, Alberto; Kakwere, Hamilton; Pellegrino, Teresa

2012-05-01

257

Nucleation and growth of ZnO nanocrystals in polymer films  

International Nuclear Information System (INIS)

A facile layer-by-layer method was used to prepare ZnO nanoparticles embedded in multilayers polymer films. The polymer matrix was formed by layer-by-layer self-assembly technique. By repetitive adsorption of zinc nitrate and subsequent precipitation with ammonium hydroxide, polyelectrolyte multilayer films containing ZnO nanoparticles were fabricated. UV-vis spectra indicate the regular growth of ZnO nanoparticles. Transmission electron microscopy study shows that morphology of the nanoparticles is controlled by the precipitation cycles number. The formation process of the nanoparticles in the multilayers was also discussed

2008-07-31

258

Nucleation and growth of ZnO nanocrystals in polymer films  

Energy Technology Data Exchange (ETDEWEB)

A facile layer-by-layer method was used to prepare ZnO nanoparticles embedded in multilayers polymer films. The polymer matrix was formed by layer-by-layer self-assembly technique. By repetitive adsorption of zinc nitrate and subsequent precipitation with ammonium hydroxide, polyelectrolyte multilayer films containing ZnO nanoparticles were fabricated. UV-vis spectra indicate the regular growth of ZnO nanoparticles. Transmission electron microscopy study shows that morphology of the nanoparticles is controlled by the precipitation cycles number. The formation process of the nanoparticles in the multilayers was also discussed.

Wang Chunlei [Key Laboratory of Polyoxometalate Science of Ministry of Education, Department of Chemistry, Northeast Normal University, Ren Min Street No. 5268, Changchun, Jinlin 130024 (China); Wang Enbo [Key Laboratory of Polyoxometalate Science of Ministry of Education, Department of Chemistry, Northeast Normal University, Ren Min Street No. 5268, Changchun, Jinlin 130024 (China)], E-mail: wangenbo@public.cc.jl.cn; Lan Yang; Li Qiuyu; Mao, Baodong; Tian, Chungui [Key Laboratory of Polyoxometalate Science of Ministry of Education, Department of Chemistry, Northeast Normal University, Ren Min Street No. 5268, Changchun, Jinlin 130024 (China)

2008-07-31

259

Functionalized nanocrystal-tagged fluorescent polymer beads: synthesis, physicochemical characterization, and immunolabeling application.  

Science.gov (United States)

A methodology for incorporating solubilized CdSe/ZnS core/shell nanocrystals (NCs) into functionalized carboxylated polystyrene latexes 0.3-1 microm in diameter via a swelling procedure was developed and used for the production of homogeneous, highly fluorescent polymeric beads (HFPBs), which were found to be comparable in brightness to standard polymeric microspheres doped with organic fluorophores and more photostable than the latter by more than 50 times (Fluoresbrite yellow-orange microspheres were used as an example). The three-dimensional (3D) confocal analysis of individual 1-microm HFPB demonstrated that the beads were doped with the NCs almost homogeneously. HFPBs 0.3 microm in diameter were conjugated with anti-mouse polyvalent immunoglobulins and used for immunofluorescent detection of p-glycoprotein, a mediator of the multidrug resistance phenotype, overexpressed in the membrane of MCF7r breast adenocarcinoma cells. The photostability of NCs-tagged HFPBs offers obvious advantages for the reconstruction of 3D confocal fluorescence images of antigen distribution, and their exceptionally high brightness combined with photostability permits the detection of a single antigen molecule using a standard epifluorescence microscope. PMID:15494132

Stsiapura, Vitali; Sukhanova, Alyona; Artemyev, Mikhail; Pluot, Michel; Cohen, Jacques H M; Baranov, Alexandre V; Oleinikov, Vladimir; Nabiev, Igor

2004-11-15

260

Electro- and photo- chromism of hybrid conducting polymers  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Polythiophenes are an important representative class of conjugated polymers that form some of the most environmentally and thermally stable materials that can be used as electrical conductors, nonlinear optical devices, polymer LEDs, electrochromic windows, sensors, solar cells, polymer electronic interconnects, nanoelectronic and optical devices.1 Gaining control over the structure, properties, and function in polythiophenes continues to make the synthesis of polythiophenes a critical subjec...

Zanoni, Michele; Byrne, Robert; Diamond, Dermot

2010-01-01

 
 
 
 
261

Scanning tunneling microscopy evidence of semicrystalline and helical conducting polymer structures  

Energy Technology Data Exchange (ETDEWEB)

Scanning tunneling microscopy images of strands, microislands, and thin films formed by the conducting polymers polypyrrole tosylate, polypyrrole tetrafluoroborate, and polythiophene tetrafluoroborate are presented. The polymer strands and microislands contain two types of helical structures with diameters of 1.5-1.8 nm, a simple helix, and 5-6 nm, a superhelix. The polymer films gradually transform from an ordered crystalline array located at the anode surface to an amorphous material at the air-polymer interface.

Yang, R.; Evans, D.F. (Univ. of Minnesota, Minneapolis (USA)); Christensen, L.; Hendrickson, W.A. (3M Co., St. Paul, MN (USA))

1990-07-26

262

Correlaction Effects on the Band Gap of Conducting Polymers  

CERN Document Server

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

263

Electrochemical study of charge transfer in conducting polymers  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Aspectos cinético e termodinâmico da transferência de carga em polímeros condutores foram investigados. Um modelo de difusão restrita foi impregado para interpretar os dados obtidos por cronopotenciometria com pulso. Em filmes de poli 3-metiltiofeno, o coeficiente de difusão aparente diminuiu em fun [...] ção da espessura do filme mas ficou constante com a concentração eletrolítica. Em filmes finos, usando-se voltametria cíclica, caracterizou-se mudanças termodinâmicas, como em particular, a deconvolução das duas transferências eletrônicas envolvidas no processo. Usando-se um modelo nernstiano incluindo potenciais de interação, conseguiu-se descrever a reação para as duas etapas eletroquímicas. Finalmente, como esperado, uma correlação entre o raio iônico dos dopantes e o coeficiente de difusão aparente foi estabelecida em filmes de polipirrol. Abstract in english The kinetics and thermodynamic aspects of charge transfer in conducting polymers were investigated. A restricted diffusion model was used to analyze kinetic data obtained from pulse-chronopotentiometric experiments. In poly 3-methylthiophene, the apparent diffusion coefficient decreased with the fil [...] m thickness, whereas it remained constant with the electrolyte concentration. In thin films, thermodynamic changes were characterized by cyclic voltammetry, specifically, the deconvolution of the two electronic transfers involved in the process. Using a Nernstian model including interaction potentials, the two electrochemical steps were well described. Finally, as expected, a correlation between the ionic radius of the dopants and the apparent diffusion coefficient was established in polypyrrole films.

J.M., Pernaut; L.C., Soares; J.C., Belchior.

264

A conducting polymer/ferritin anode for biofuel cell applications  

Energy Technology Data Exchange (ETDEWEB)

An enzyme anode for use in biofuel cells (BFCs) was constructed using an electrically connected bilayer based on a glassy carbon (GC) electrode immobilized with the conducting polymer polypyrrole (Ppy) as electron transfer enhancer, and with horse spleen ferritin protein (Frt) as electron transfer mediator. The surface-coupled redox system of nicotinamide adenine dinucleotide (NADH) catalyzed with diaphorase (Di) was used for the regeneration of NAD{sup +} in the inner layer and the NAD{sup +}-dependent enzyme catalyst glucose dehydrogenase (GDH) in the outer layer. The outer layer of the GC-Ppy-Frt-Di-NADH-GDH electrode effectively catalyzes the oxidation of glucose biofuel continuously; using the NAD{sup +} generated at the inner layer of the Di-catalyzed NADH redox system mediated by Frt and Ppy provides electrical communication with enhancement in electron transport. The electrochemical characteristics of the electrodes were investigated by cyclic voltammetry (CV) and linear sweep voltammetry (LSV). This anode provides a current density of 1.2 mA cm{sup -2} in a 45 mM glucose solution and offers a good possibility for application in biofuel cells.

Inamuddin [Center for Bio-Artificial Muscle, Hanyang University, Seoul 133-791 (Korea, Republic of); Shin, Kwang Min [Center for Bio-Artificial Muscle, Hanyang University, Seoul 133-791 (Korea, Republic of); Department of Biomedical Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Kim, Sun I. [Department of Biomedical Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); So, Insuk [Center for Bio-Artificial Muscle, Hanyang University, Seoul 133-791 (Korea, Republic of); Department of Physiology, Seoul National University, Seoul 110-744 (Korea, Republic of); Kim, Seon Jeong [Center for Bio-Artificial Muscle, Hanyang University, Seoul 133-791 (Korea, Republic of); Department of Biomedical Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of)], E-Mail: sjk@hanyang.ac.kr

2009-06-30

265

Morphology tailoring of nano/micro-structured conductive polymers, composites and their applications in chemical sensors.  

Science.gov (United States)

Conductive polymer is one of the important multi-functional materials. It has many applications in light-emitting diodes, chemical sensors, biosensors, et al. This paper provides a relatively comprehensive review on the progress of conductive polymer and composite as sensitive film for sensors to chemical vapors including patents, papers and our preliminary research results. Especially, the feature of conjugated polymers, the processing technology, doping characteristics and some factors affecting gas responses are discussed. Otherwise, the developments of nanostructured conductive polymer and organic-inorganic hybrid film sensor with high sensitivity and rapid response to vapors are also described, and some suggestions are proposed. PMID:20615192

Ma, Xingfa; Gao, Mingjun; He, Xiaochun; Li, Guang

2010-11-01

266

Potential of thermally conductive polymers for the cooling of mechatronic parts  

Science.gov (United States)

Adding thermally conductive fillers to polymers the thermal conductivity can be raised significantly. Thermal conductive polymers (TC-plastics) open up a vast range of options to set up novel concepts of polymer technological system solutions in the area of mechatronics. Heating experiment of cooling ribs show the potential in thermal management of mechatronic parts with TC-polymers in comparison with widely used reference materials copper and aluminum. The results demonstrate that especially for certain thermal boundary conditions comparable performance between these two material grades can be measured.

Heinle, C.; Drummer, D.

267

Application of nano-structured conducting polymers to humidity sensing  

Science.gov (United States)

Nanostructures, such as nanowires, nanocolumns, and nanotubes, have attracted a lot of attention because of their huge potential impact on a variety of applications. For sensor applications, nanostructures provide high surface area to volume ratios. The high surface area to volume ratio allows more reaction areas between target species and detection materials and also improves the detection sensitivity and response time. The main goal of this research was to exploit the advantages and develop innovative methods to accomplish the synthesis of nanowires and nano-coulmn conducting polymers used in humidity detection. To accomplish this, two fabrication methods are used. The first one utilizes the geometric confinement effect of a temporary nanochannel template to orient, precisely position, and assemble Polyaniline (PANI) nanowires as they are synthesized. The other approach is to simply spin-coat a polymer onto a substrate, and then oxygen plasma etch to generate a nano-columned Polyethylenedioxythiophene (PEDOT) thin film. 200 nm silicon oxide coated wafers with embedded platinum electrodes are used as a substrate for both fabrication methods. The biggest advantage of this first method is that it is simple, requires a single-step, i.e., synthesizing and positioning procedures are carried out simultaneously. The second method is potentially manufacturable and economic yet environmentally safe. These two methods do not produce extra nano-building materials to discard or create a health hazard. Both PANI nanowires and nano-columned PEDOT films have been tested for humidity detection using a system designed and built for this research to monitor response (current changes) to moisture, To explain the surface to volume ratio effect, 200 nm PANI nanowires and 10 microm PANI wires were directly compared for detecting moisture, and it was shown that the PANI nanowire had a better sensitivity. It was found difficult to monitor the behaviors of the PEDOT reaction to varying moisture levels because even low humidity levels saturate the sample surface within a few minutes. Because of this, it was not perfect to distinguish the effects of etching the PEDOT film for humidity detection and difficult to apply nano-columned PEDOT films as a humidity sensors under continuously changing humidity conditions. However, nano-columned PEDOT films showed excellent performance in simulated breath tests, i.e., an area where the medical needs sensors for pulmonary monitoring. Since the polymers are sensitive to heat, it was important to characterize the influence of temperature on the sensor performance. PANI nanowires and nano-columned PEDOT sensors were tested in the environmental chamber developed in this work as a function of temperature with the humidity fixed, and only the temperature was varied. The PANI nanowires showed very fast degradation at temperatures above room temperature, while the nano-columned PEDOT film performed up to 50 °C. The influence of other gases was also tested for the potential of gas sensing, selectivity, and chemical stability. In order to exclude the moisture effect during the measurement, the samples were characterized under the lowest humidity condition, RH 14% preserved in the system. Under these conditions the PANI nanowires responded to the gases (hydrogen and carbon monoxide were used), but the moisture inside the PANI nanowire was forced to influence the gas detection. Therefore, samples were dried overnight under a nitrogen environment and tested again. With this careful control of the moisture present, it was found that PANI nanowires respond to both hydrogen and carbon monoxide gases, however, there is no selectivity between gases. Nano-columned PEDOT films were also tested under the same experimental moisture-controlling conditions. It was shown that there was little response to other gases. Any response that may have been presented was buried in the electrical noise. Finally, both samples were tested for long-term stability. PANI nanowires showed almost linear degradation with continuous use, while nano-c

Park, Pilyeon

268

Influence of Conducting Polymers Based on Carboxylated Polyaniline on In Vitro CaCO3 Crystallization  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Conducting polymers are interesting materials of technological applications, while the use of polymers as additives controlling crystal nucleation and growth is a fast growing research field. In the present article, we make a first step in combining both topics and report the effect of conducting polymer derivatives, which are based on carboxylated polyanilines (c-PANIs), on in vitro CaCO3 crystallization by the Kitano and gas diffusion method. This is the first example of the mineralization ...

Neira-carrillo, Andronico; Acevedo, Diego F.; Miras, Maria C.; Barbero, Cesar A.; Gebauer, Denis; Co?lfen, Helmut; Arias, Jose L.

2008-01-01

269

A proton-doped calix[4]arene-based conducting polymer.  

Science.gov (United States)

Segmented conducting polymers based upon a calix[4]arene scaffold are reported. The cone conformation creates a zigzag orientation of the polymer segments. Their acid-dependent conductivities are similar to the strong pH conductivity dependence of polyaniline which is said to be acid dopable. On the other hand, they have a segmented structure that imposes greater localization of the carriers. The conductivity of such a system can be considered to result from rapid self-exchange between discrete units. Hence, electron exchange between radical cations and p-diquinone salts produces the high conductivity of these polymers. PMID:12553796

Yu, Hsiao-Hua; Xu, Bing; Swager, Timothy M

2003-02-01

270

Directly patternable, highly conducting polymers for broad applications in organic electronics  

Science.gov (United States)

Postdeposition solvent annealing of water-dispersible conducting polymers induces dramatic structural rearrangement and improves electrical conductivities by more than two orders of magnitude. We attain electrical conductivities in excess of 50 S/cm when polyaniline films are exposed to dichloroacetic acid. Subjecting commercially available poly(ethylene dioxythiophene) to the same treatment yields a conductivity as high as 250 S/cm. This process has enabled the wide incorporation of conducting polymers in organic electronics; conducting polymers that are not typically processable can now be deposited from solution and their conductivities subsequently enhanced to practical levels via a simple and straightforward solvent annealing process. The treated conducting polymers are thus promising alternatives for metals as source and drain electrodes in organic thin-film transistors as well as for transparent metal oxide conductors as anodes in organic solar cells and light-emitting diodes.

Yoo, Joung Eun; Lee, Kwang Seok; Garcia, Andres; Tarver, Jacob; Gomez, Enrique D.; Baldwin, Kimberly; Sun, Yangming; Meng, Hong; Nguyen, Thuc-Quyen; Loo, Yueh-Lin

2010-01-01

271

Directly patternable, highly conducting polymers for broad applications in organic electronics.  

Science.gov (United States)

Postdeposition solvent annealing of water-dispersible conducting polymers induces dramatic structural rearrangement and improves electrical conductivities by more than two orders of magnitude. We attain electrical conductivities in excess of 50 S/cm when polyaniline films are exposed to dichloroacetic acid. Subjecting commercially available poly(ethylene dioxythiophene) to the same treatment yields a conductivity as high as 250 S/cm. This process has enabled the wide incorporation of conducting polymers in organic electronics; conducting polymers that are not typically processable can now be deposited from solution and their conductivities subsequently enhanced to practical levels via a simple and straightforward solvent annealing process. The treated conducting polymers are thus promising alternatives for metals as source and drain electrodes in organic thin-film transistors as well as for transparent metal oxide conductors as anodes in organic solar cells and light-emitting diodes. PMID:20212152

Yoo, Joung Eun; Lee, Kwang Seok; Garcia, Andres; Tarver, Jacob; Gomez, Enrique D; Baldwin, Kimberly; Sun, Yangming; Meng, Hong; Nguyen, Thuc-Quyen; Loo, Yueh-Lin

2010-03-30

272

Mixed ionic and electronic conductivity in polymers. Progress report, January 1, 1991--December 31, 1991  

Energy Technology Data Exchange (ETDEWEB)

In the past year, we have made progress in the theory of mixed ionic and electronic conductivity in polymers. On the experimental side, we have prepared polypyrroles with pendant polyethers and studied their conductivity in the reduced state. Theoretical progress was made in the application of Monte Carlo methods to ion motion in polymers.

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

1992-07-01

273

Hydrogel-mediated direct patterning of conducting polymer films with multiple surface chemistries.  

Science.gov (United States)

A new methodology for selective electropolymerization of conducting polymer films using wet hydrogel stamps is presented. The ability of this simple method to generate patterned films of conducting polymers with multiple surface chemistries in a one-step process and to incorporate fragile biomolecules in these films is demonstrated. PMID:24623531

Park, SooHyun; Yang, Guang; Madduri, Nrutya; Abidian, Mohammad Reza; Majd, Sheereen

2014-05-01

274

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.

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

2013-08-01

275

Evaluation of solid polymer electrolytes for use in conducting polymer/nanotube actuators  

Science.gov (United States)

The stringent requirements for a solid polymer electrolyte (SPE) in solid state devices such as batteries or supercapacitors are even more demanding when used in electromechanical actuators. Not only is the SPE expected to exhibit good conductivity, mechanical properties, adhesion and mechanical/electrical stability, but it must also be flexible, maintained good adhesion while flexing, be easily processible and be able to function in air. In this work polyacrylonitrile and Kynar based non-aqueous SPEs and water based polyacrylamide hydrogel ion source/sinks containing various perchlorate salts were tested for their applicability to polypyrrole and carbon nanotube actuators and supercapacitors. The results indicate that the optimum SPE for both polypyrrole and carbon nanotube actuators would be a polyacrylonitrile plasticized with propylene carbonate and ethylene carbonate containing 1.0M NaClO4. It is also apparent that the same SPE would be the most suitable for supercapacitor applications with these materials.

Lewis, Trevor W.; Kim, B. C.; Spinks, Geoffrey M.; Wallace, Gordon G.

2000-06-01

276

Performance of conducting polymer electrodes for stimulating neuroprosthetics  

Science.gov (United States)

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, R. A.; Matteucci, P. B.; Hassarati, R. T.; Giraud, B.; Dodds, C. W. D.; Chen, S.; Byrnes-Preston, P. J.; Suaning, G. J.; Poole-Warren, L. A.; Lovell, N. H.

2013-02-01

277

Nanocrystal structures  

Energy Technology Data Exchange (ETDEWEB)

A structure including a grating and a semiconductor nanocrystal layer on the grating, can be a laser. The semiconductor nanocrystal layer can include a plurality of semiconductor nanocrystals including a Group II-VI compound, the nanocrystals being distributed in a metal oxide matrix. The grating can have a periodicity from 200 nm to 500 nm.

Eisler, Hans J. (Stoneham, MA); Sundar, Vikram C. (Stoneham, MA); Walsh, Michael E. (Everett, MA); Klimov, Victor I. (Los Alamos, NM); Bawendi, Moungi G. (Cambridge, MA); Smith, Henry I. (Sudbury, MA)

2008-12-30

278

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

279

A polymer electrolyte with high luminous transmittance and low solar throughput : Polyethyleneimine-lithium bis(trifluoromethylsulfonyl) imide with In2O3:Sn nanocrystals  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Chemically prepared similar to 13-nm-diameter nanocrystals of In2O3:Sn were included in a polyethyleneiminelithium bis(trifluoromethylsulfonyl) imide electrolyte and yielded high haze-free luminous transmittance and strong near-infrared absorption without deteriorated ionic conductivity. The optical properties could be reconciled with effective medium theory, representing the In2O3:Sn as a free electron plasma with tin ions screened according to the random phase approximation corrected for el...

Bayrak Pehlivan, I.; Runnerstrom, E. L.; Li, Shuyi; Niklasson, Gunnar A.; Milliron, D. J.; Granqvist, Claes-go?ran

2012-01-01

280

Effects of ?-rays on electrical conductivity of polyvinyl alcohol-polypyrrole composite polymer films  

International Nuclear Information System (INIS)

The composite polymer films of polyvinyl alcohol/polypyrrole/chloral hydrate (PVA-PPy-CH) had been prepared. Effects of ?-rays on the electrical conductivity of the composite polymer films had been investigated by using Inductance Resistance meter (LCR) meter at a frequency ranging from 20 Hz to 1 MHz. With the incorporation of choloral hydrate in the polymer sample, the conductivity increased indicates that it is capable to be used as dopant for polymerizing conjugated polymer. The electrical conductivity obtained increased as the dose increased, which is in the order of 10-5 Scm-1 indicates that ?-ray is capable to enhance the electrical conductivity of the composite polymer films. The parameter of s is in the range of 0.31 ? S ? 0.49 and obeyed simple power law dispersion ?S. The Scanning Electron Microscopy (SEM) micrographs reveal the formation of polypyrrole globules in polyvinyl alcohol matrix which increased as the irradiation dose was increased. (Author)

2007-01-01

 
 
 
 
281

Investigation on the effects of beta and gamma irradiation on conducting polymers for sensor applications  

Energy Technology Data Exchange (ETDEWEB)

Two conductive polymers were evaluated to be the active materials in a sensor device for the detection of beta radiation. This was accomplished by characterizing the changes in conductivity of electrically conducting polymer films caused by exposure to tritium gas for varying lengths of time. The behavior of these materials when exposed to gamma radiation was also studied to gain further insight into the mechanism of conductivity degradation by ionizing radiation. Two types of conductive polymer, polyaniline (PANi) and poly(3,4-ethylenedioxythiophene) (PEDOT), were chosen as candidate materials for their widespread commercial use. The change of surface resistance (conductivity) of PANi and PEDOT films when exposed to gamma radiation in both air and deuterium environments was evaluated as well as tritium exposures in 10{sup 4} and 10{sup 5} Pa gas. Raman and absorbance spectra of gamma irradiated samples were obtained to determine the mechanism of conductivity degradation in both polymers. Post-irradiation gas analysis of the samples contained in deuterium revealed very little (or no) hydrogen in the containment vessel, indicating that hydrogen-deuterium isotopic exchange was not responsible for the decrease in surface conductivity due to gamma exposure. The effects of irradiation-induced oxidation were also studied for both conductive polymers during gamma irradiation. It was concluded that chain scission via free radical formation and chain cross-linking are most likely the two dominant mechanisms for conductivity change and not de-protonation of the polymer.

Kane, Marie C., E-mail: mkane@sandia.go [Savannah River National Laboratory, Aiken, SC 29808 (United States); Sandia National Laboratories, Livermore, CA 94550 (United States); Lascola, Robert J.; Clark, Elliot A. [Savannah River National Laboratory, Aiken, SC 29808 (United States)

2010-12-15

282

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

283

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.

Hjelm, Johan

2012-01-01

284

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

285

Terahertz phase contrast imaging of sorption kinetics in porous coordination polymer nanocrystals using differential optical resonator.  

Science.gov (United States)

The enhancement of light-matter coupling when light is confined to wavelength scale volumes is useful both for studying small sample volumes and increasing the overall sensing ability. At these length scales, nonradiative interactions are of key interest to which near-field optical techniques may reveal new phenomena facilitating next-generation material functionalities and applications. Efforts to develop novel chemical or biological sensors using metamaterials have yielded innovative ideas in the optical and terahertz frequency range whereby the spatially integrated response over a resonator structure is monitored via the re-radiated or leaked light. But although terahertz waves generally exhibit distinctive response in chemical molecules or biological tissue, there is little absorption for subwavelength size sample and therefore poor image contrast. Here, we introduce a method that spatially resolves the differential near-field phase response of the entire resonator as a spectral fingerprint. By simultaneously probing two metallic ring resonators, where one loaded with the sample of interest, the differential phase response is able to resolve the presence of guest molecules (e.g. methanol) as they are adsorbed or released within the pores of a prototypical porous coordination polymer. PMID:24921804

Blanchard, F; Sumida, K; Wolpert, C; Tsotsalas, M; Tanaka, T; Doi, A; Kitagawa, S; Cooke, D G; Furukawa, S; Tanaka, K

2014-05-01

286

Spectroscopic investigations on hybrid nanocomposites: CdS : Mn nanocrystals in a conjugated polymer  

International Nuclear Information System (INIS)

We have used electron paramagnetic resonance (EPR) spectroscopy for investigating the properties of spins, such as those carried by polarons which carry both spin and charge in poly (meta/para phenylene) PMPP: CdS doped Mn based nanocomposites. To identify the nature of paramagnetic species in PMPP matrix, we have studied the effect of different physical parameters. It was found that we are in presence of trapped polarons and localized spins which concentration has been estimated. Moreover, spin-spin and spin-lattice relaxation rates have been calculated. Then, we discussed the results of optical and EPR study on the hybrid nanocomposite (CdS nanostructures, doped with manganese (II) ions, incorporated in PMPP conjugated polymer matrix). The optical spectra of these nanocomposites were compared to the existing models of energy levels in quantum dots. Moreover, by the use of electronic paramagnetic resonance, conclusions about the location and the symmetry of Mn2+ ions have been drawn. The nanocomposite energy gap is in the 3.2-3.3 eV range. The size of the nanoparticle is about 3.3 nm and Mn2+ ions are located at or near the nanoparticle surface

2006-03-01

287

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

CERN Document Server

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

288

Nanostructured surface made from polymer/carbon nanotube has higher conductivity than noble metal surface  

Science.gov (United States)

We made a nanostructured surface by directly coating carbon nanotubes to a surface that was previously solvent-coated with a polymer/CNT composite. Compared to the surface coated with the same polymer composite where the surface carbon nanotubes were buried in the matrix polymer, the surface directly coated with carbon nanotubes had a significant amount of exposed nanostructures. The surface was immersed in an electrolyte solution. Its AC conductivity was higher than that of a Pt/Ir surface.

Lyu, Suping; Coles, James; Gardenski, Ken; Brabec, Scott; Hobot, Chris

2010-03-01

289

Síntese de polímeros condutores em matrizes sólidas hospedeiras Conductive polymer synthesis in solid host matrices  

Directory of Open Access Journals (Sweden)

Full Text Available This review discusses the methods used to prepare conductive polymers in confined environments. This spatial restriction causes formation of defect-free polymer chains in the interlayer as porous cavities of inorganic hosts. The properties of the different composites obtained are a synergist combination of the characteristics of the inorganic host and the polymer. This opens new perspectives for the preparation of these materials and widens its potential applications.

Daltamir J. Maia

2000-04-01

290

Conducting polymers as driving electrodes for Polymer-Dispersed Liquid-Crystals display devices: On the electro-optical efficiency  

Science.gov (United States)

Intrinsically conducting polymer (ICP) thin films are used as driving electrodes for Polymer-Dispersed Liquid-Crystals (PDLC) display devices. In order to investigate the electro-optical efficiency of these organic electrodes, three different kinds of conducting polymers, i.e. polyaniline doped with 10-camphorsulfonic acid (PANI(HCSA)), polypyrrole doped with dodecylbenzenesulfonic acid (PPY(DBSA)), and polyethylenedioxythiophene doped with polystyrenesulfonate (PEDOT(PSS)), were prepared or purchased, and coated either on glass or plastic substrates. Optical absorption studies in the UV-Vis range of the conducting polymer-coated substrates were first performed showing the presence of conducting species for the three types of polymers. The electrical characteristics of the resulting films were measured with the four-probes technique. PANI(HCSA) exhibits a higher conductivity ?sim 122\\un{S\\cdot cm^{-1}} (R_S=1.2 ; 10^3; ?\\cdotBox^{ -1}) compared to PPY(DBSA) ?sim 2.6\\un{S\\cdot cm^{-1}} (R_S=150.7 ;10^3;?\\cdotBox^{-1}), and PEDOT(PSS) ?sim 1.6\\un{S\\cdot cm^{-1}} (R_S=637.3 ; 10^3; ?\\cdotBox^{-1}). It is also shown that for a given conducting polymer, its electrical conductivity decreases when a plastic substrate is used. These observations have been related to significant morphological changes observed by scanning electron microscopy (SEM). A mixture of Norland Optical Adhesive 65 and nematic liquid-crystal E7 in the weight ratio (\\chem{35:65}) was used as precursor of the PDLC material. Better electro-optical responses (transmission properties, drive voltages and switching times) of PDLC films were obtained for devices prepared with (PPY(DBSA))-based electrodes. The electro-optical performances of the PDLC display devices also depend on the nature of the ICP substrate used.

Roussel, F.; Chan-Yu-King, R.; Buisine, J.-M.

2003-07-01

291

Conducting polymers as driving electrodes for Polymer-Dispersed Liquid-Crystals display devices: on the electro-optical efficiency.  

Science.gov (United States)

Intrinsically conducting polymer (ICP) thin films are used as driving electrodes for Polymer-Dispersed Liquid-Crystals (PDLC) display devices. In order to investigate the electro-optical efficiency of these organic electrodes, three different kinds of conducting polymers, i.e. polyaniline doped with 10-camphorsulfonic acid (PANI(HCSA)), polypyrrole doped with dodecylbenzenesulfonic acid (PPY(DBSA)), and polyethylenedioxythiophene doped with polystyrenesulfonate (PEDOT(PSS)), were prepared or purchased, and coated either on glass or plastic substrates. Optical absorption studies in the UV-Vis range of the conducting polymer-coated substrates were first performed showing the presence of conducting species for the three types of polymers. The electrical characteristics of the resulting films were measured with the four-probes technique. PANI(HCSA) exhibits a higher conductivity sigma approximately 122 S x cm(-1) (RS=1.2x10(3) Omega x (-1)) compared to PPY(DBSA) sigma approximately 2.6 S x cm(-1) (RS=150.7x10(3) Omega x (-1)), and PEDOT(PSS) sigma approximately 1.6 S x cm(-1) (RS=637.3x10(3) Omega x (-1)). It is also shown that for a given conducting polymer, its electrical conductivity decreases when a plastic substrate is used. These observations have been related to significant morphological changes observed by scanning electron microscopy (SEM). A mixture of Norland Optical Adhesive 65 and nematic liquid-crystal E7 in the weight ratio (35:65) was used as precursor of the PDLC material. Better electro-optical responses (transmission properties, drive voltages and switching times) of PDLC films were obtained for devices prepared with (PPY(DBSA))-based electrodes. The electro-optical performances of the PDLC display devices also depend on the nature of the ICP substrate used. PMID:15011049

Roussel, F; Chan-Yu-King, R; Buisine, J-M

2003-07-01

292

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

293

Fabrication of embedded conductive layer in polymer by plasma immersion ion implantation  

Science.gov (United States)

Plasma immersion ion implantation (PIII) offers an alternative to ion beam with the advantage of high implantation rate. However, problems inherent to the application of PIII to non-conducting materials such as polymers are due to surface charging. To overcome these difficulties and to have a controllable implantation depth, we sputtered a thin layer of gold before PIII is applied to the polymer substrate. The result is a controllable implantation dept and stronger adhesion between the metal-polymer interfaces. The extent of implantation depth can be correlated to tribological properties, electrical conductivity and Raman spectroscopy. While conductive AFM confirmed the conductivity of the embedded layer, the future applications, difficulties and limitations using this technique for fabrication of conductive embedded layer in polymers are also discussed.

Ha, Peter C. T.; Han, Z. J.; Tay, B. K.

2007-01-01

294

Tuning the thermal conductivity of solar cell polymers through side chain engineering.  

Science.gov (United States)

Thermal transport is critical to the performance and reliability of polymer-based energy devices, ranging from solar cells to thermoelectrics. This work shows that the thermal conductivity of a low band gap conjugated polymer, poly(4,8-bis-alkyloxybenzo[1,2-b:4,5-b']dithiophene-2,6-diyl-alt-(alkylthieno[3,4-b]thiophene-2-carboxylate)-2,6-diyl) (PBDTTT), for photovoltaic applications can be actively tuned through side chain engineering. Compared to the original polymer modified with short branched side chains, the engineered polymer using all linear and long side chains shows a 160% increase in thermal conductivity. The thermal conductivity of the polymer exhibits a good correlation with the side chain lengths as well as the crystallinity of the polymer characterized using small-angle X-ray scattering (SAXS) experiments. Molecular dynamics simulations and atomic force microscopy are used to further probe the molecular level local order of different polymers. It is found that the linear side chain modified polymer can facilitate the formation of more ordered structures, as compared to the branched side chain modified ones. The effective medium theory modelling also reveals that the long linear side chain enables a larger heat carrier propagation length and the crystalline phase in the bulk polymer increases the overall thermal conductivity. It is concluded that both the length of the side chains and the induced polymer crystallization are important for thermal transport. These results offer important guidance for actively tuning the thermal conductivity of conjugated polymers through molecular level design. PMID:24643840

Guo, Zhi; Lee, Doyun; Liu, Yi; Sun, Fangyuan; Sliwinski, Anna; Gao, Haifeng; Burns, Peter C; Huang, Libai; Luo, Tengfei

2014-05-01

295

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

2012-01-01

296

Role of electron and hole transport processes in conductivity and light emission of silicon nanocrystals field-effect transistors  

Science.gov (United States)

In this work, the optoelectronic properties of silicon light emitting field-effect transistors (LEFETs) have been investigated. The devices have been fabricated with silicon nanocrystals in the gate oxide and a semitransparent polycrystalline silicon gate. We compare the properties of LEFET with a more conventional MOS-LED (two-terminal light-emitting capacitor) with the same active material. The ~45 nm thick gate siliconrich oxide is deposited in a size-controlled multilayer geometry by low pressure chemical vapor deposition using standard microelectronic processes in a CMOS line. The multilayer stack is formed by layers of silicon oxide and silicon rich silicon oxide. The nanocrystal size and the tunneling barrier width are controlled by the thickness of silicon-rich silicon oxide and stochiometric silicon oxide layers, respectively. The silicon nanocrystals have been characterized by means of spectrally and time resolved photoluminescence, high resolution TEM, and x-ray photoelectron spectroscopy. Resistivity of the devices, capacitance, and electroluminescence under direct and pulsed injection current scheme have been studied and here reported. The optical power density and the external quantum efficiency of the LEFETs will be compared with the MOSLED results. This study will help to develop practical optoelectronic and photonic devices via accurate modeling and engineering of charge transport and exciton recombination in silicon nanocrystal arrays.

Cattoni, Laura; Tengattini, Andrea; Anopchenko, Aleksei; Ram?rez, Joan Manel; Ferrarese Lupi, Federico; Berencen, Yonder; Garrido, Blas; Fedeli, Jean-Marc; Pavesi, Lorenzo

2013-02-01

297

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

298

3D fabrication of all-polymer conductive microstructures by two photon polymerization.  

Science.gov (United States)

A technique to fabricate electrically conductive all-polymer 3D microstructures is reported. Superior conductivity, high spatial resolution and three-dimensionality are achieved by successive application of two-photon polymerization and in situ oxidative polymerization to a bi-component formulation, containing a photosensitive host matrix and an intrinsically conductive polymer precursor. By using polyethylene glycol diacrylate (PEG-DA) and 3,4-ethylenedioxythiophene (EDOT), the conductivity of 0.04 S/cm is reached, which is the highest value for the two-photon polymerized all-polymer microstructures to date. The measured electrical conductivity dependency on the EDOT concentration indicates percolation phenomenon and a three-dimensional nature of the conductive pathways. Tunable conductivity, biocompatibility, and environmental stability are the characteristics offered by PEG-DA/EDOT blends which can be employed in biomedicine, MEMS, microfluidics, and sensorics. PMID:24514677

Kurselis, Kestutis; Kiyan, Roman; Bagratashvili, Victor N; Popov, Vladimir K; Chichkov, Boris N

2013-12-16

299

Conductivity and thermal studies of solid polymer electrolytes prepared by blending polyvinylchloride, polymethylmethacrylate and lithium sulfate  

Energy Technology Data Exchange (ETDEWEB)

Composite polymer electrolyte films consisting of polyvinylchloride, polymethymethacrylate, dibutylphthalate, Li{sub 2}SO{sub 4} and also ZrO{sub 2} particles have been prepared by a casting procedure. The effect of an inorganic filler on the ionic conductivity of the blend polymer electrolytes was studied. The results indicated the incorporation of the ceramic filler at a low level decreases the ionic conductivity of the material, while at the higher concentrations there is an improvement of the conductivity. From the temperature dependence of the ionic conductivity can be suggested that the ion conduction follows the Williams-Landel-Ferrry mechanism, which is confirmed by Vogel-Tammann-Fulcher plots.

Uma, T.; Mahalingam, T.; Stimming, U

2004-05-15

300

Conductivity and thermal studies of solid polymer electrolytes prepared by blending polyvinylchloride, polymethylmethacrylate and lithium sulfate  

International Nuclear Information System (INIS)

Composite polymer electrolyte films consisting of polyvinylchloride, polymethymethacrylate, dibutylphthalate, Li2SO4 and also ZrO2 particles have been prepared by a casting procedure. The effect of an inorganic filler on the ionic conductivity of the blend polymer electrolytes was studied. The results indicated the incorporation of the ceramic filler at a low level decreases the ionic conductivity of the material, while at the higher concentrations there is an improvement of the conductivity. From the temperature dependence of the ionic conductivity can be suggested that the ion conduction follows the Williams-Landel-Ferrry mechanism, which is confirmed by Vogel-Tammann-Fulcher plots

2004-05-15

 
 
 
 
301

Spin injection behavior in conducting polymer coated superparamagnetically functional microstructures  

Science.gov (United States)

A nanoferrite superparamagnetic system synthesized through co-precipitation method and subsequently dispersed in a medium of de-ionized water was encapsulated with a matrix polymer under constant sonication using chemical oxidative polymerization technique. The polymer coated functional microstructure thus obtained shows enhanced magnetization as evidenced from the results reported elsewhere. The magnetic core crystal growth and anti-spin canting hypothesis were given to be the most general justification behind the unusual enhancement in magnetization and more specifically the rationale could understand recently in accordance with spin injection behavior in functional core-shell microstructures. In this paper, an attempt has been made to correlate the previous magnetization results with spin injection behavior, in conjunction with the thermo gravimetric and dielectric results.

Prasad, Arun S.

2014-06-01

302

Photoluminescence of virgin and conducting polymer infiltrated synthetic opals  

International Nuclear Information System (INIS)

Luminescence of a synthetic opal excited by N2-laser radiation (337 nm) is investigated. The luminescence spectrum has shown the spectral maximums at 430 nm and 535 nm. Its duration is very short (no more than 9 ns). According to the results the luminescence spectrum and its intensity depend on the irradiation time. The photonic band gap was shown to deform the luminescence spectra of the opal registered 'on transmission' and the polymer infiltrated into the opal. (author)

2003-09-01

303

Process modeling of conductivity in nanocomposites based on reticulated polymers and carbon nanotubes  

International Nuclear Information System (INIS)

The dependences of electric conductivities of thermosetting polymer nanocomposites based on epoxy polymer and polycyanurate filled by carbon nanotubes were investigated. Low values of percolation threshold at volume fraction of carbon nanotubes from 0.001 to 0.002 were observed for all samples.Absolute values of the percolation threshold are in good agreement with the results of mathematical modeling. It is established that electrical properties of thermosetting polymer nanocomposites can be characterized in the frame of the same theoretical model despite difference in polymers properties

2012-10-10

304

Ionic Conductivity and Dielectric Studies of Chitin Nanofiber (CNF) Incorporated PMMA Based Polymer Electrolytes  

Science.gov (United States)

Chitin nanofibers (CNF) are synthesized from shrimp cell chitin by stepwise purification and acid hydrolysis method. PMMA based polymer electrolytes complexed with LIN (CF3SO2)2 and chitin nanofibers as nanofiller have prepared by membrane hot-press technique. The prepared composite electrolytes are subjected to FT-IR, ac impedance, dielectric and modulus analyses. The incorporation of nanofiller in the polymer matrix increases the conductivity by an order of magnitude compared with filler free electrolytes. The complexation behavior of the composite polymer electrolytes are investigated by ATR FT -IR spectroscopy. The electric modulus analysis and dielectric studies of polymer electrolytes revealed that the non Debye dielectric relaxation nature.

Shyly, P. M.; Karuppasamy, K.; Linda, T.; Thiravetyan, Paitip; Balakumar, S.; Sahaya, Shajan X.

2012-06-01

305

Conducting polymer/nanodiamond composites: New opportunities and scientific challenges for material science  

Science.gov (United States)

We present some recent results of a systematic study regarding polymer-based nanocomposites with carbon nanostructures as guest components. This paper is focused on the coupling of conductive polymers, as polyanilines and polythiophenes, with nanodiamond grains. The peculiar properties of such crystalline nanomaterial not only help in improving the mechanical and thermal properties of the host polymeric matrices, but also act on the polymerization mechanism, modifying the morphological features of the polymers. Triggered by the nanodiamond presence, the final nanocomposites show a prominent arrangement of polymer segments into tubular forms and a subsequent structural organization suitable for many technological applications.

Terranova, Maria Letizia; Tamburri, Emanuela; Guglielmotti, Valeria; Toschi, Francesco; Orlanducci, Silvia; Passeri, Daniele; Rossi, Marco

2012-07-01

306

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

307

Redox-exchange induced heterogeneous RuO2-conductive polymer nanowires.  

Science.gov (United States)

A redox exchange mechanism between potassium perruthenate (KRuO4) and the functional groups of selected polymers is used here to induce RuO2 into and onto conductive polymer nanowires by simply soaking the polymer nanowire arrays in KRuO4 solution. Conductive polymer nanowire arrays of polypyrrole (PPY) and poly(3,4-ethylenedioxythiophene) (PEDOT) were studied in this work. SEM and TEM results show that the RuO2 material was distributed differently in the PPY and PEDOT nanowire matrices. Energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy were used to confirm the dispersion and formation of RuO2 materials in these polymer nanowires. Cyclic voltammetry and galvanostatic charge-discharge experiments were used to characterize their electrochemical performance. RuO2-polymer samples prepared with a 6 min soaking time in 10 mM KRuO4 solution show a high specific capacitance of 371 F g(-1) and 500 F g(-1) for PEDOT-based and PPY-based composite nanowires, respectively. This is attributed to the high exposure area of the conductive RuO2 and the good conductivity of the polymer matrix. This work demonstrates a simple method to synthesize heterogeneous polymer based-materials through the redox reaction between conductive polymers and high oxidation state transition metal oxide ions. Different heterogeneous nanocomposites were obtained depending on the polymer properties, and high energy storage performance of the metal oxides can be achieved within these heterogeneous nanostructures. PMID:24824847

Gui, Zhe; Duay, Jonathon; Hu, Junkai; Lee, Sang Bok

2014-06-28

308

Ion irradiation induced electrochemical stability enhancement of conducting polymer electrodes in super-capacitors  

International Nuclear Information System (INIS)

We have explored the effects of 120 MeV Si9+ ion beam irradiation on the electrical, structural and capacitance properties of HClO4 doped poly-aniline conducting polymer electrodes. The swift heavy ion (SHI) irradiated conducting polymer films exhibited up to 70% increase in crystallinity and dc conductivity with improved surface morphology. The super-capacitors fabricated with ion irradiated poly-aniline electrodes showed enhancement of electrochemical stability and slight decrease in internal resistance, which could be attributed to the removal or stabilization of the volatile surface groups and decrease in surface roughness upon ion irradiation. Fluence dependent small increase in coulombic efficiency is observed in the super-capacitors with SHI irradiated polymer electrodes because of the increase in dc conductivity of the polymer electrodes upon irradiation. (authors)

2006-11-01

309

THE ELECTROCHEMISTRY OF ANTIBODY-MODIFIED CONDUCTING POLYMER ELECTRODES. (R825323)  

Science.gov (United States)

Abstract The modification of conducting polymer electrodes with antibodies (i.e. proteins) by means of electrochemical polymerization is a simple step that can be used to develop an immunological sensor. However, the electrochemical processes involved leading to the ge...

310

Structure-induced enhancement of thermal conductivities in electrospun polymer nanofibers.  

Science.gov (United States)

Polymers that are thermally insulating in bulk forms have been found to exhibit higher thermal conductivities when stretched under tension. This enhanced heat transport performance is believed to arise from the orientational alignment of the polymer chains induced by tensile stretching. In this work, a novel high-sensitivity micro-device platform was employed to determine the axial thermal conductivity of individual Nylon-11 polymer nanofibers fabricated by electrospinning and post-stretching. Their thermal conductivity showed a correlation with the crystalline morphology measured by high-resolution wide-angle X-ray scattering. The relationship between the nanofiber internal structures and thermal conductivities could provide insights into the understanding of phonon transport mechanisms in polymeric systems and also guide future development of the fabrication and control of polymer nanofibers with extraordinary thermal performance and other desired properties. PMID:24932733

Zhong, Zhenxin; Wingert, Matthew C; Strzalka, Joseph; Wang, Hsien-Hau; Sun, Tao; Wang, Jin; Chen, Renkun; Jiang, Zhang

2014-06-26

311

The synthesis of conducting polymers for corrosion prevention  

Science.gov (United States)

The formation of an electrically conducting form of polyaniline by the oxidative polymerization of aniline was studied. Optimum yield and conductivities were obtained by treating aniline in 2 molar hydrochloric acid at 0 to 5 C with ammonium persulfate in 1.15 mole ratio. The yield was 37.6 percent of theory and the conductivity of the product was 10.5 S/cm. This material was formulated into epoxy and acrylic coatings which were also electrically conductive.

Mattson, Guy C.

1988-01-01

312

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

1997-10-01

313

Design, synthesis, characterization and development of novel organic conducting polymers with technological applications  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this thesis, a series of novel organic conducting polymers have been synthesized using alternative methods based on electrochemical techniques, which have allowed to broaden the knowledge in the field of the characterization by means of topological, spectroscopic, electrochemical and structural techniques. Among the variety of synthesis techniques of conducting polymers, layer-by-layer (LbL) has been one of the most important to build multilayered systems. Thus, in this thesis ...

Aradilla Zapata, David

2013-01-01

314

Properties and processing by extrusion of electrically conductive multilayer filaments comprising polymer composites  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This work describes the production and characterization of three-layer piezoelectric filaments using two different electrically conductive polymers. The filaments were produced in a filament extrusion line, equipped with a coextrusion die that enabled a coaxial arrangement for a three-layer filament. For the inner and outer layers two different electrically conductive compounds were used, and the middle layer was made of the electroactive polymer PVDF. The produced filament can be used as a p...

Martins, R. S.; Gonc?alves, Renato Ferreira; Azevedo, Tiago; No?brega, J. M.; Carvalho, Helder; Lanceros-me?ndez, S.; Rocha, J. G.

2013-01-01

315

DOPANT FLEXIBILITY AND PROCESSABILITY STUDIES WITH ELECTRICALLY CONDUCTIVE, FACE-TO-FACE METALLOMACROCYCLIC POLYMERS  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In doping experiments on the cofacially arrayed phthalocyanine polymer [Si(Pc)O]n using high potential quinone, halogen, or nitrosyl electron acceptors, the achievable degree of partial oxidation, the inhomogeneity of the doping process, and the conductivity mechanism remain remarkably constant. Using wet spinning techniques, it has proven possible to prepare electrically conductive fibers of [Si(Pc)O]n alone or blended with the high performance aramid polymer Kevlar.

Inabe, T.; Lyding, J.; Moguel, M.; Marks, T.

1983-01-01

316

Low-Magnetic Field Microwave Absorption in Superconductors and Conducting Polymers  

Science.gov (United States)

Low-magnetic field microwave absorption (MA) in superconductors and conducting polymers is analysed in a low-field signal (LFS) version of the MA detecting method. The temperature dependences, hysteretic benavior and other properties of a LFS are compared in superconducting versus non-superonducting systems. Spin selective hopping processes between polarons and bipolarons is proposed to be one of the possible mechanisms of a LFS in non-degenarate conducting polymers.

Khairullin, I. L.; Khabibullaev, P. K.; Sokolov, V. Yu.; Zakhidov, A. A.

1999-07-01

317

Highly Electrically Conductive Nanocomposites Based on PolymerInfused Graphene Sponges  

Science.gov (United States)

Conductive polymer composites require a threedimensional 3D network to impart electrical conductivity. A general method that is applicable to most polymers for achieving a desirable graphene 3D network is still a challenge. We have developed a facile technique to fabricate highly electrical conductive composite using vacuumassisted infusion of epoxy into graphene sponge GS scaffold. Macroscopic GSs were synthesized from graphene oxide solution by a hydrothermal method combined with freeze drying. The GSepoxy composites prepared display consistent isotropic electrical conductivity around 1Sm, and it is found to be close to that of the pristine GS. Compared with neat epoxy, GSepoxy has a 12ordersofmagnitude increase in electrical conductivity, attributed to the compactly interconnected graphene network constructed in the polymer matrix. This method can be extended to other materials to fabricate highly conductive composites for practical applications such as electronic devices, sensors, actuators, and electromagnetic shielding.

Li, Yuanqing; Samad, Yarjan Abdul; Polychronopoulou, Kyriaki; Alhassan, Saeed M.; Liao, Kin

2014-01-01

318

Highly Electrically Conductive Nanocomposites Based on PolymerInfused Graphene Sponges  

Science.gov (United States)

Conductive polymer composites require a threedimensional 3D network to impart electrical conductivity. A general method that is applicable to most polymers for achieving a desirable graphene 3D network is still a challenge. We have developed a facile technique to fabricate highly electrical conductive composite using vacuumassisted infusion of epoxy into graphene sponge GS scaffold. Macroscopic GSs were synthesized from graphene oxide solution by a hydrothermal method combined with freeze drying. The GSepoxy composites prepared display consistent isotropic electrical conductivity around 1Sm, and it is found to be close to that of the pristine GS. Compared with neat epoxy, GSepoxy has a 12ordersofmagnitude increase in electrical conductivity, attributed to the compactly interconnected graphene network constructed in the polymer matrix. This method can be extended to other materials to fabricate highly conductive composites for practical applications such as electronic devices, sensors, actuators, and electromagnetic shielding.

Li, Yuanqing; Samad, Yarjan Abdul; Polychronopoulou, Kyriaki; Alhassan, Saeed M.; Liao, Kin

2014-04-01

319

Mixed ionic-electronic conduction and percolation in polymer electrolyte metal oxide composites. Final report  

Energy Technology Data Exchange (ETDEWEB)

For any battery or electrochemical power source, it is necessary to optimize the performance of the electrolyte and the electrodes. While work on polymer solid electrolytes has advanced substantially, there are a number of very important and difficult issues involved in electrode optimization. The results from numerous experimental cells and whole-cell models (from Newman`s group at Berkeley) indicate that conduction within the polymer electrolyte phase of the composite is a major limiting factor for the attainment of suitable power densities. This project is aimed at understanding and optimizing both electronic and ionic conduction properties in composite electrode structures based on polymer electrolytes.

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

1997-06-01

320

Electrochemical patterning of the surface of insulators with electrically conductive polymers  

Energy Technology Data Exchange (ETDEWEB)

The great potential of {pi}-conjugated polymers, especially polyacetylene, polyarylenes, and poly(arylenevinylene)s, as components in optical displays, sensors, rechargeable batteries, electromagnetic interference shielding, and microelectronics is well recognized. This paper presents a protocol for patterning the surface of insulators with electrically conductive polymers. The pattern is formed on a gold electrode surface via electro-oxidation of heteroarene monomers. An adhesion layer is used to bond the surface of the conducting polymer pattern to the surface of an insulator. The pattern is then developed by etching away the gold. The approach is illustrated with polypyrrole and is applicable to a wide range of substituted polyheteroarenes and insulating substrates.

Zheng, X.Y.; Ding, Y.; Bottomley, L.A. [Georgia Inst. of Tech., Atlanta, GA (United States)

1995-12-01

 
 
 
 
321

DC conduction in polymers under high electric fields  

Energy Technology Data Exchange (ETDEWEB)

The results of current-voltage (I-V) characteristics measured at different temperatures in polyethylene (PE) films obtained by our own experiments and the ones extracted from Suh K S et al (2000 J. Appl. Phys. 87 7333) are presented. The current depended strongly on temperature, namely, it increased with increase of temperature. The non-linearity in the I-V behaviour was observed at higher voltages. We suggest a phonon-assisted tunnelling model to explain the experimental results. The current mechanism in polymer diphenylaminostyrylbenzene (DASMB) films and in tris(8-hydroxyquinoline) aluminium (Alq{sub 3}) films are also discussed.

Pipinys, P; Rimeika, A; Lapeika, V [Department of Physics, Vilnius Pedagogical University, LT 2034 (Lithuania)

2004-03-21

322

DC conduction in polymers under high electric fields  

International Nuclear Information System (INIS)

The results of current-voltage (I-V) characteristics measured at different temperatures in polyethylene (PE) films obtained by our own experiments and the ones extracted from Suh K S et al (2000 J. Appl. Phys. 87 7333) are presented. The current depended strongly on temperature, namely, it increased with increase of temperature. The non-linearity in the I-V behaviour was observed at higher voltages. We suggest a phonon-assisted tunnelling model to explain the experimental results. The current mechanism in polymer diphenylaminostyrylbenzene (DASMB) films and in tris(8-hydroxyquinoline) aluminium (Alq3) films are also discussed

2004-03-21

323

Conducting polymers as ion transport and solid electrolyte materials  

Science.gov (United States)

The structure-property relationships in a series of poly (1,4-bis(2-heterocycle)-p-phenylenes) (PBHPs) and poly (3,12-bis(2-heterocycle)-p-dialkylfluorenes) (PBHDFs) as well as the use of polypyrrole (PPy) as solid electrolyte for tantalum capacitors have been investigated. PBHPs, where the heterocycle is thiophene or pyrrole, and PBHDFs, where the heterocycle is thiophene or ethylenedioxythiophene (EDOT), were synthesized electrochemically and their electrochemical properties studied using cyclic voltammetry. The ion transport characteristics of the polymers were investigated using the electrochemical quartz microbalance (EQCM) while the electronic properties of the polymers were studied using optoelectrochemical and in situ electron paramagnetic resonance (EPR)/electrochemical techniques. The electrochemical and electronic properties of PBHPs and PBHDFs have been found to be highly dependent on the nature of the heterocycle and on the pendant side groups substituents. Alkoxy substitution on the phenylene rings results in a marked decrease in the monomer and polymer oxidation potentials and a decrease in the electronic band gap. Substitution with long-chain alkoxy groups results in the formation of stable paramagnetic charge carriers at intermediate doping levels. Also, metallic-like character was observed at high doping levels. The presence of electron-rich heterocycles (e.g., pyrrol, EDOT) as terminal electropolymerizable units on the multi-ring conjugated monomers leads to stabilization of the cation-radical intermediates allowing the electropolymerization to be carried out at low potentials. The ion transport behavior of these polymers under electrochemical switching was found to be anion dominant. PPy as solid electrolyte for tantalum capacitors was prepared using a combination of chemical and electrochemical methods, antraquinone-2-sulfonate (AQSsp-) was used as the dopant ion. The redox properties of PPy were studied by cyclic voltammetry while compositional analysis were carried out using X-ray photoelectron spectroscopy (XPS). UV-Vis spectroscopy was used to check the stability of PPy to spontaneous ion-exchange of AQSsp{-}. The dielectric properties of the capacitors were measured in order to determine the optimum conditions for PPy deposition. The capacitors prepared showed excellent high frequency performance up to 100 kHz and long term stability.

Larmat Gonzalez, Fernando Enrique

1997-12-01

324

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.

Lawrence T. Drzal

2010-02-01

325

Synthesis and conductivity of PEGME branched poly(ethylene-alt-maleimide) based solid polymer electrolyte  

International Nuclear Information System (INIS)

A thermally stable comb-like polymer electrolyte, poly(ethylene glycol) monomethyl ether (PEGME) grafted poly(ethylene-alt-maleimide), has been synthesized and characterized. The copolymer was thermally stable up to 250.deg.C and had good film forming property. The copolymer was well mixed with poly(ethylene glycol) dimethyl ether(PEGDME, Mw = 400). The activation energy of ionic conduction decreased and conductivity increased with the increase of PEGDME content in the polymer electrolyte. The maximum conductivity of the resulting polymer electrolyte containing 66 wt% of PEGDME was found to be 3 x 10-4 S/cm at 30.deg.C. The polymer electrolyte showed electrochemical stability window of greater than 4.7 V

2000-02-01

326

Exploiting redox chemistries to manipulate structure and electrical conductivity in polymer acid-doped polyaniline  

Science.gov (United States)

Template synthesis of polyaniline on poly(2-acrylamido-2-methyl-1-propanesulfonic acid) yields electrostatically stabilized particles that can be aqueously dispersed and cast into thin films; electrical conductivity in these films scales with inter-particle connectivity. Previous research has shown that solvent annealing with dichloroacetic acid (DCA) induces structural rearrangement of polymer chains and consequently enhances the electrical conductivity by up to two orders of magnitude (from 0.4 to 40 S/cm). Alternatively, the electrostatic interactions between polyaniline and its template can be neutralized through chemical reduction with hydrazine monohydrate, after which the polymer undergoes extensive structural rearrangement; subsequent exposure to nitric oxide leads to reassociation of polyaniline and its polymer acid dopant. Enhanced conductivity is observed following this chemical redox process, and is attributed to extensive polymer chain relaxation and concurrent elimination of the particulate nature of template-synthesized polyaniline.

Tarver, Jacob; Fan, Joline; Loo, Yueh-Lin

2011-03-01

327

Hybrid nanostructures based on the conducting polymers incorporated to porous silicon matrix  

International Nuclear Information System (INIS)

An influence of conducting polymer on the structure, morphology and luminescent characteristics of porous silicon - conducting polymer hybrid nanostructures has been studied. The incorporation of conducting polymers such as polyphenylacetylene (PPA), polyepoxypropyle carbazole, polyparaphenylene (PPP), polyaniline to porous silicon matrix was provided by magnetron deposition, electropolymerization and dip coating. The hybrid layers were studied by FT-IR spectroscopy, scanning electron and atom force microscopy and examined on the ability to photo- and cathode luminescence (CL). For the hybrid nanostructured layers based on PPA and PPP a significant increasing in the luminescence intensity has been found. According to FT-IR spectroscopy the interaction between polymer functional groups and porous silicon surface takes a place. Probably it leads to decreasing a rate of non-radiation surface recombination and to increasing a radiation component of recombination as well as increasing in the CL total intensity.

2011-04-01

328

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

2011-09-01

329

Li-ion conduction in PVAc based polymer blend electrolytes for lithium battery applications  

International Nuclear Information System (INIS)

Highlights: ? PVAc/PVdF-co-HFP based polymer blend electrolyte for various concentration of LiClO4 were prepared and characterized. ? It is found that all the prepared electrolyte systems exhibited a maximum ionic conductivity of the order of x10-4 Scm-1. ? Surface morphology of the polymer electrolyte membrane sample having maximum ionic conductivity is studied by atomic force microscopy. ? SEM and DSC studies were also carried in the present study. - Abstract: The present work describes the Li-ion conduction in Poly(vinyl acetate) (PVAc) based polymer blend electrolytes have been synthesized by solvent casting technique for lithium battery applications. Characterization by XRD, SEM, AFM, FTIR, TG/DTA and photoluminescence was performed for synthesized polymer electrolytes. The thermal behaviour of the samples was ascertained from differential scanning calorimeter (DSC) and TG/DTA. The temperature dependence of conductivity of the polymer electrolytes was measured and the maximum ionic conductivity of 0.5269 x 10-4 Scm-1 at 303 K for PVAc:PVdF-co-HFP ((25/75) wt%):LiClO4 (8 wt%) complex. Surface morphology was examined from various surface scanning techniques such as scanning electron microscope (SEM) and atomic force microscope (AFM). Photoluminescence measurements demonstrated that the PVAc based polymer blend electrolyte shows minimum intensity and the results are detailed in this paper.

2011-09-15

330

Conductive polymers for controlled release and treatment of central nervous system injury  

Science.gov (United States)

As one of the most devastating forms of neurotrauma, spinal cord injury remains a challenging clinical problem. The difficulties in treatment could potentially be resolved by better technologies for therapeutic delivery. In order to develop new approaches to treating central nervous system injury, this dissertation focused on using electrically-conductive polymers, controlled drug release, and stem cell transplantation. We first sought to enhance the therapeutic potential of neural stem cells by electrically increasing their production of neurotrophic factors (NTFs), important molecules for neuronal cell survival, differentiation, synaptic development, plasticity, and growth. We fabricated a new cell culture device for growing neural stem cells on a biocompatible, conductive polymer. Electrical stimulation via the polymer led to upregulation of NTF production by neural stem cells. This approach has the potential to enhance stem cell function while avoiding the pitfalls of genetic manipulation, possibly making stem cells more viable as a clinical therapy. Seeing the therapeutic potential of conductive polymers, we extended our studies to an in vivo model of spinal cord injury (SCI). Using a novel fabrication and extraction technique, a conductive polymer was fabricated to fit to the characteristic pathology that follows contusive SCI. Assessed via quantitative analysis of MR images, the conductive polymer significantly reduced compression of the injured spinal cord. Further characterizing astroglial and neuronal response of injured host tissue, we found significant neuronal sparing as a result of this treatment. The in vivo studies also demonstrated improved locomotor recovery mediated by a conductive polymer scaffold over a non-conductive control. We next sought to take advantage of conductive polymers for local, electronically-controlled release of drugs. Seeking to overcome reported limitations in drug delivery via polypyrrole, we first embedded drugs in poly[(D,L-lactide-co-glycolide)-co-polyethylene glycol] (PLGA-PEG) nanoparticles and then demonstrated scalable incorporation and controlled release. In a functional application, electronically-controlled release of minocycline nanoparticles was used to rescue primary spinal cord neurons from an excitotoxic environment in vitro. This approach offers a wide range of therapeutic possibilities, especially for treating traumatic lesions of the central nervous system. Finally, we explored use of conductive polymers for directed differentiation of progenitor cells. Retinal progenitors were seeded on custom polypyrrole cell culture devices and subjected to a biomimetic pattern of electrical stimulation. Stimulated cells showed phenotypic changes, increased neurite outgrowth, increased immunocytochemical expression of cone rod homeobox (CRX) and protein kinase C (PK-C), and decreased expression of glial fibrillary acidic protein (GFAP). Biomimetic stimulation thus led cells towards early photoreceptor and bipolar cell fates, and away from an astrocytic cell fate. Electrical stimulation via a conductive polymer offers a novel approach for directing differentiation of progenitor cells.

Saigal, Rajiv

331

Mechanical Properties of Nanocrystal Supercrystals  

Energy Technology Data Exchange (ETDEWEB)

Colloidal nanocrystals attract significant interest due to their potential applications in electronic, magnetic, and optical devices. Nanocrystal supercrystals (NCSCs) are particularly appealing for their well ordered structure and homogeneity. The interactions between organic ligands that passivate the inorganic nanocrystal cores critically influence their self-organization into supercrystals, By investigating the mechanical properties of supercrystals, we can directly characterize the particle-particle interactions in a well-defined geometry, and gain insight into both the self-assembly process and the potential applications of nanocrystal supercrystals. Here we report nanoindentation studies of well ordered lead-sulfide (Pbs) nanocrystal supercrystals. Their modulus and hardness were found to be similar to soft polymers at 1.7 GPa and 70 MPa respectively and the fractures toughness was 39 KPa/m1/2, revealing the extremely brittle nature of these materials.

Tam, Enrico; Podsiadlo, Paul; Shevchenko, Elena; Ogletree, D. Frank; Delplancke-Ogletree, Marie-Paule; Ashby, Paul D.

2009-12-30

332

Elucidating interactions and conductivity of newly synthesised low bandgap polymer with protic and aprotic ionic liquids.  

Science.gov (United States)

In this paper, we have examined the conductivity and interaction studies of ammonium and imidazolium based ionic liquids (ILs) with the newly synthesised low bandgap polymer (Poly(2-heptadecyl-4-vinylthieno[3,4-d]thiazole) (PHVTT)). Use of low bandgap polymers is the most suitable way to harvest a broader spectrum of solar radiations for solar cells. But, still there is lack of most efficient low bandgap polymer. In order to solve this problem, we have synthesised a new low bandgap polymer and investigated its interaction with the ILs to enhance its conductivity. ILs may undergo almost unlimited structural variations; these structural variations have attracted extensive attention in polymer studies. The aim of present work is to illustrate the state of art progress of implementing the interaction of ILs (protic and aprotic ILs) with newly synthesised low bandgap polymer. In addition to this, our UV-Vis spectroscopy, confocal Raman spectroscopy and FT-IR spectroscopy results have revealed that all studied ILs (tributylmethylammonium methyl sulfate ([N1444][MeSO4] from ammonium family) and 1-methylimidazolium chloride ([Mim]Cl, and 1-butyl-3-methylimidazolium chloride ([Bmim]Cl from imidazolium family) have potential to interact with polymer. Our semi empirical calculation with help of Hyperchem 7 shows that protic IL ([Mim]Cl) interacts strongly with the low bandgap polymer through the H-bonding. Further, protic ILs shows enhanced conductivity than aprotic ILs in association with low bandgap polymer. This study provides the combined effect of low bandgap polymer and ILs that may generate many theoretical and experimental opportunities. PMID:23874829

Attri, Pankaj; Lee, Seung-Hyun; Hwang, Sun Woo; Kim, Joong I L; Lee, Sang Woo; Kwon, Gi-Chung; Choi, Eun Ha; Kim, In Tae

2013-01-01

333

Evaluation of the electrical conductivity of polypyrrole polymer composites  

Science.gov (United States)

A study of the electrical conductivity of polypyrrole-polyoxyphenylene composites (PPy-POP and PPy-POP-MPcTS) prepared by in situ electropolymerization is presented, where MPcTS stands for tetrasulfonated tetrasodium metallophthalocyanine salts and is used as a second dopand for polypyrrole. The conductivity is studied as a function of temperature in the range 77?T?300 K. The temperature dependence of the total ac conductivity, in the frequency range 102-105 Hz, changes by approximately five orders of magnitude, showing a sub-linear dispersive behaviour. The temperature dependence of the dc conductivity gives evidence for a transport mechanism based on the Mott's variable-range hopping model in one dimension for the PPy-POP composite, which shows a crossover to three dimensions for the PPy-POP-MPcTS composites. Using this model we were able to calculate meaningful values for the density of states, hopping energy and hopping distance.

Aguilar-Hernández, J.; Potje-Kamloth, K.

2001-06-01

334

Carbon black (CB)-filled conductive polymer composites: CB distribution and electrical properties  

Science.gov (United States)

Carbon black (CB) distribution and electrical properties of CB-filled conductive polymer composites were studied theoretically and experimentally in detail. Several important fundamental issues have been addressed. The CB distribution in a neat semicrystalline polymer was elucidated using RuO4 vapor staining technique and transmission electron microscopy (TEM). It has been found that CB particles were presented between the lamellae of the semicrystalline polymer. Based on the TEM results, schematic models for the CB distribution in neat semicrystalline polymers were developed. The CB distribution in binary immiscible polymer blends was investigated theoretically and experimentally. A thermodynamic model was derived to predict CB distribution in immiscible polymer blends. The predictions obtained by simulation agreed very well with the experimental observations. An in-complete wetting model was also developed for the case when one of the two polymer components has a very high viscosity. The positive temperature coefficient (PTC) and negative temperature coefficient (NTC) effects of CB-filled a semicrystalline polyurethane-based shape memory polymer (SMP) composites were studied. It has been observed that apart from the CB content and the CB type, thermal aging could impose a pronounced influence on their PTC and NTC effects. The PTC and NTC effects of CB-filled immiscible polymer blends were investigated. Some novel physical effects, such as double-PTC effect, have been observed and explained in terms of their morphological features. Schematic models were also given to predict the PTC and NTC effects of the composites with different morphologies. The effects of mechanical strain on the electrical resistance of CB-filled neat polymers and immiscible polymer blends were elucidated. Positive strain coefficient (PSC) and negative strain coefficient (NSC) effects were observed and explained using tunneling junction and two-process models. A CB-filled neat polymer composite that is very sensitive to mechanical strain was also successfully prepared, which has potential applications in making strain sensors.

Feng, Jiyun

335

Enhancement of electrical conductivity of ion-implanted polymer films  

International Nuclear Information System (INIS)

The electrical conductivity of ion-implanted films of Nylon 66, Polypropylene (PP), Poly(tetrafluoroethylene) (Teflon) and mainly Poly (ethylene terephthalate) (PET) was determined by DC measurements at voltages up to 4500 V and compared with the corresponding values of pristine films. Measurements were made at 21"0C +/- 1"0C and 65 +/- 2% RH. The electrical conductivity of PET films implanted with F"+, Ar"+, or As"+ ions at energies of 50 keV increases by seven orders of magnitude as the fluence increases from 1 x 10"1"8 to 1 x 10"2"0 ions/m"2. The conductivity of films implanted with As"+ was approximately one order greater than those implanted with Ar"+, which in turn was approximately one-half order greater than those implanted with F"+. The conductivity of the most conductive film ?1 S/m) was almost 14 orders of magnitude greater than the pristine PET film. Except for the three PET samples implanted at fluences near 1 x 10"2"0 ions/m"2 with F"+, Ar"+, and As"+ ions, all implanted films were ohmic up to an electric field strength of 600 kV/m. The temperature dependence of the conductivity of the three PET films implanted near a fluence of 1 x 10"2"0 ions/m"2 was measured over the range of 80 K < T < 300 K

1985-01-01

336

Directly patternable, highly conducting polymers for broad applications in organic electronics  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Postdeposition solvent annealing of water-dispersible conducting polymers induces dramatic structural rearrangement and improves electrical conductivities by more than two orders of magnitude. We attain electrical conductivities in excess of 50 S/cm when polyaniline films are exposed to dichloroacetic acid. Subjecting commercially available poly(ethylene dioxythiophene) to the same treatment yields a conductivity as high as 250 S/cm. This process has enabled the wide incorporation of conduc...

Yoo, Joung Eun; Lee, Kwang Seok; Garcia, Andres; Tarver, Jacob; Gomez, Enrique D.; Baldwin, Kimberly; Sun, Yangming; Meng, Hong; Nguyen, Thuc-quyen; Loo, Yueh-lin

2010-01-01

337

Simulation of ultraviolet- and soft X-ray-pulse generation as a result of cooperative recombination of excitons in diamond nanocrystals embedded in a polymer film  

International Nuclear Information System (INIS)

Using numerical simulation, it is shown that the recombination of free excitons photoexcited in diamond nanocrystals embedded in a polymer film can occur in the cooperative mode. It is found that this mode can be implemented despite the fact that diamond is an “indirect” semiconductor. It is shown that the power of the generated radiation at the pulse peak during the cooperative recombination of free excitons can exceed that of the incoherent spontaneous emission of the same initial number of free excitons by more than an order of magnitude. Finally, it is shown that the process under consideration can be used to generate picosecond pulses of ultraviolet and soft X-ray electromagnetic field at a wavelength of 235 nm

2013-11-01

338

Oxireductases in the Enzymatic Synthesis of Water-Soluble Conducting Polymers  

Science.gov (United States)

This chapter reviews recent advances in the field of biocatalytic synthesis of water-soluble conducting polymers. Biocatalysis is proposed as a versatile tool for synthesis of conducting polymers. First, the enzymatic synthesis of conducting polymers and its mechanism is discussed as well as the use of different type of enzymes. Next, we describe the use of a new bifunctional template (sodium dodecyl diphenyloxide disulfonate) in the synthesis of polyaniline as a strategy to improve the water solubility and electrical conductivity in the obtained polymer. The recent development of enzyme-catalyzed polymerization of 3,4-ethylenedioxythiophene (EDOT) in the presence of polystyrenesulfonate is discussed. This method results in PEDOT materials that show an electrical conductivity of 2 × 1{0}^{-3} {S cm}^{-1} and posses excellent film formation ability, as confirmed by atomic force microscopy images. Finally, a simple method for immobilizing horseradish peroxidases in the biocatalytic synthesis of water-soluble conducting polymers is presented. This method is based on a biphasic catalytic system in which the enzyme is encapsulated inside the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate, while other components remain in the aqueous phase. The enzyme is easily recovered after reaction and can be reused several times.

Ochoteco, Estibalitz; Mecerreyes, David

339

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,

2013-02-01

340

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

 
 
 
 
341

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

342

Conductive polymer patterned media fabricated by diblock copolymer lithography for scanning multiprobe data storage  

International Nuclear Information System (INIS)

A conductive polymer dot pattern has been fabricated as a patterned medium using diblock copolymer lithography (DCL) for scanning multiprobe data storage systems (SMDSSs). DCL can easily provide a higher dots pattern density than that obtained using electron beam lithography. For DCL, the microphase-separated structure of polystyrene-block-polymethylmethacrylate is utilized. Then, the closed dot pattern of polyaniline (PANI) with a center to center distance of adjacent dots of 30 nm is fabricated by DCL. Electrical modification experiments of the fabricated PANI dots are demonstrated using scanning probe microscopy (SPM). As a result, the conductivities of the modified dots are selectively changed by applying modification voltages with the tip of the SPM probe. Recording on the conductive polymer with 30 nm pitch at the minimum can be demonstrated, which corresponds to a recording density of ?700 Gbits inch-2. These results show that the conductive polymer patterned medium has the potential ability to achieve high-density recording for SMDSSs.

2008-11-26

343

Determination of physical parameters of conducting polymers by photothermal spectroscopies  

Science.gov (United States)

Photothermal spectroscopies, photopyroelectric and photoacoustic, were used to obtain physical parameters of polyaniline-emeraldine base (PANI-EB) and poly(o-methoxyaniline)-emeraldine base (POMA-EB), such as thermic parameters like thermal diffusivity, thermal conductivity, and specific heat. These studies were done for PANI-EB and POMA-EB films in the 400PANI and POMA films and the pyroelectric detector, were used to fit the experimental results. It was observed that, in contrast with the strong doping dependence of the electrical conductivity, the thermal parameters of PANI films remained practically unchanged under doping. This apparent discrepancy is explained by the granular metal model of doped PANI.

de Albuquerque, J. E.; Melo, W. L. B.; Faria, R. M.

2003-01-01

344

Electron Transfer Between Colloidal ZnO Nanocrystals  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Colloidal ZnO nanocrystals, capped with dodecylamine and dissolved in toluene, can be charged photochemically to give stable solutions in which electrons are present in the conduction bands of the nanocrystals. These conduction band electrons are readily monitored by EPR spectroscopy, with g* values that correlate with the nanocrystal sizes. Mixing a solution of charged small nanocrystals with a solution of uncharged large nanocrystals, e-CB:ZnO–S + ZnO–L, causes changes in the EPR spectr...

Hayoun, Rebecca; Whitaker, Kelly M.; Gamelin, Daniel R.; Mayer, James M.

2011-01-01

345

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

346

Functionalization of conducting polymer with novel Co(II) complex: Electroanalysis of ascorbic acid  

International Nuclear Information System (INIS)

We report for the first time the functionalization of a conducting polymer with a metal complex in order to develop a new type of catalytic material exhibiting better electronic communication through their delocalized ? electrons. The Co(II) complex having hydroxyl group as functional moiety is chemically coupled with carboxyl group of polyanthranilic acid which itself is a self doped conducting polymer. The covalent linkage between Co(II) and -OH group is confirmed using UV-vis, FT-IR and NMR spectroscopic techniques. The Co(II) complex functionalized polymer does exhibit excellent redox behavior and stability with mixed properties of Co(II) complex and ?-conjugated polymer. The material possesses potential benefits in sensors/biosensor applications and it is demonstrated for the electroanalysis of ascorbic acid at a level of nano molar concentration.

2010-06-15

347

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

International Nuclear Information System (INIS)

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

348

Síntese de polímeros condutores em matrizes sólidas hospedeiras / Conductive polymer synthesis in solid host matrices  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese [...] Abstract in english This review discusses the methods used to prepare conductive polymers in confined environments. This spatial restriction causes formation of defect-free polymer chains in the interlayer as porous cavities of inorganic hosts. The properties of the different composites obtained are a synergist combina [...] tion of the characteristics of the inorganic host and the polymer. This opens new perspectives for the preparation of these materials and widens its potential applications.

Daltamir J., Maia; Marco-A., De Paoli; Oswaldo L., Alves; Aldo J. G., Zarbin; Silmara das, Neves.

349

Probing alamethicin channels with water-soluble polymers. Effect on conductance of channel states.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Channel access resistance has been measured to estimate the characteristic size of a single ion channel. We compare channel conductance in the presence of nonpenetrating water-soluble polymers with that obtained for polymer-free electrolyte solution. The contribution of the access resistance to the total alamethicin channel resistance is approximately 10% for first three open channel levels. The open alamethicin channel radii inferred for these first three levels from the access resistance ar...

1993-01-01

350

Process for depositing strong adherend polymer coating onto an electrically conductive surface  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Process for depositing by electrografting a strong adherent polymer coating onto an electrically conductive surface comprising an electrochemical grafting at the surface of an active monomer for forming a primer coating P onto said surface and having as general formula: X0 (meth)acrylate wherein X is either part of a preformed polymer or is an intermediate agent for polyaddition reaction or is an anchoring group for attachment of a molecule having at least one complementary reactive group. Su...

Bertrand, Olivier; Je?ro?me, Robert; Gautier, Sandrine; Maquet, Ve?ronique; Detrembleur, Christophe; Je?ro?me, Christine; Voccia, Samuel; Claes, Michae?l; Lou, Xudong; Labaye, David-emmanuel

2002-01-01

351

Process for depositing strong adherend polymer coating onto an electrically conductive surface  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Process for depositing by electrografting a strong adherent polymer coating onto an electrically conductive surface comprising the step of electrochemical grafting of an active monomer for forming a primer coating P onto the surface and having as general formula: X0 (meth)acrylate wherein X is either part of a preformed polymer or is an intermediate agent for polyaddition reaction or is an anchoring group for attachment of a molecule having at least one complementary reactive group. Such proc...

Bertrand, Olivier; Je?ro?me, Robert; Gautier, Sandrine; Maquet, Ve?ronique; Detrembleur, Christophe; Je?ro?me, Christine; Voccia, Samuel; Claes, Michae?l; Lou, Xudong; Labaye, David-emmanuel

2003-01-01

352

High Yield Sample Preconcentration Using a Highly Ion-conductive Charge-selective Polymer  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The development and analysis of a microfluidic sample preconcentration system using a highly ion-conductive charge-selective polymer (poly-AMPS) is reported. The preconcentration is based on the phenomenon of concentration polarization which develops at the boundaries of the poly-AMPS with buffer solutions. A negatively charged polymer, poly-AMPS, positioned between two microchannels efficiently extracts cations through its large cross section, resulting in efficient anion sample preconcentra...

2010-01-01

353

Conducting polymer-based hybrid assemblies for electrochemical sensing: a materials science perspective  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this topical review, progress achieved in amperometric sensing of different analytes over conducting polymer-based hybrid electrocatalysts is summarized. We report a variety of synthetic methods and the resulting hybrid assemblies, with the effectiveness of such strategies, for designing conjugated polymer-based hybrids as robust sensors for amperometric detection. Beyond incorporation of metal nanoparticles, metal-oxide and non-oxide semiconductors, carbon-based nanomaterials (nanotubes, ...

2013-01-01

354

Conducting polymers from aminobenzoic acids and aminobenzenesulphonic acids: influence of pH on electrochemical behaviour  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The influence of pH on the electrochemical behaviour of conducting polymer films electrosynthesised from aminobenzoic acids and aminobenzenesulphonic acids was investigated by voltammetric and electrochemical impedance studies in sulphuric acid solution, acetate buffer and neutral phosphate buffer. The change in electrochemical behaviour with increasing pH is significantly less for poly(aminobenzenesulphonic acid)s and poly(aminobenzoic acid)s than for polyaniline. Polymer films made by elect...

Brett, Christopher M. A.; Thiemann, Carolin

2002-01-01

355

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

356

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 i...

2003-01-01

357

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

358

Copper Selenide Nanocrystals for Photothermal Therapy  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Ligand-stabilized copper selenide (Cu2?xSe) nanocrystals, approximately 16 nm in diameter, were synthesized by a colloidal hot injection method and coated with amphiphilic polymer. The nanocrystals readily disperse in water and exhibit strong near infrared (NIR) optical absorption with a high molar extinction coefficient of 7.7 × 107 cm?1 M?1 at 980 nm. When excited with 800 nm light, the Cu2?xSe nanocrystals produce significant photothermal heating with a photothermal transduction e...

Hessel, Colin M.; Pattani, Varun; Rasch, Michael; Panthani, Matthew G.; Koo, Bonil; Tunnell, James W.; Korgel, Brian A.

2011-01-01

359

Insight into the conductivity mechanism of polymer electrolytes provided by positron annihilation lifetime spectroscopy  

International Nuclear Information System (INIS)

Full text: DC conductivity measured from polymer electrolytes is typically non-Arrhenius and is most often described by free volume (FV) theory. To determine if polymer FV can be used exclusively to describe the solvated mobile ions, the pressure and temperature dependence of both the conductivity and FV of a polymer electrolyte have been measured and evaluated for the first time. FV theory was supported by the observation of: 1. a linear dependence of conductivity on hole volume (Vh) as measured by PALS; 2. zero Vh occurring at a temperature very close to the zero mobility temperature (T0) obtained from a VTF fit to the temperature dependence of the DC conductivity. Conductivity measured as a function of pressure allowed the calculation of VA, which can be considered as an increase in volume required for ionic motion to occur. Critical volumes calculated from two current FV models were found to be unrealistic. Combining VA with Vh at the same temperature resulted in a more realistic and 'model-free' figure for the critical volume. A comparison of the isothermal and isobaric dependence of conductivity on Vh-1 illustrates that FV cannot be considered the sole factor responsible for conductivity in polymer electrolytes. Copyright (2005) Australian Institute of Physics

2005-02-04

360

Thermal Conductivity of Polymer/Nano-filler Blends  

Science.gov (United States)

To improve the thermal conductivity of an ethylene vinyl acetate copolymer, Elvax 260 was compounded with three carbon based nano-fillers. Multiwalled carbon nanotubes (MWCNT), vapor grown carbon nanofibers (CNF) and expanded graphite (EG) were investigated. In an attempt to improve compatibility between the Elvax and nanofillers, MWCNTs and EGs were modified through non covalent and covalent attachment of alkyl groups. Ribbons were extruded to form samples in which the nanofillers were aligned, and samples were also fabricated by compression molding in which the nano-fillers were randomly oriented. The thermal properties were evaluated by DSC and TGA, and mechanical properties of the aligned samples were determined by tensile testing. The degree of dispersion and alignment of the nanoparticles were investigated using high-resolution scanning electron microscopy. Thermal conductivity measurements were performed using a Nanoflash technique. The thermal conductivity of the samples was measured in both the direction of alignment as well as perpendicular to that direction. The results of this study will be presented.

Ghose, Sayata; Watson, Kent A.; Delozier, Donovan M.; Working, Dennis C.; Connell, John W.; Smith, Joseph G.; Sun, Y. P.; Lin, Y.

2006-01-01

 
 
 
 
361

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

Science.gov (United States)

An all-polymer micropump was realized using the conductive polymer poly (3,4-ethylenedioxythiophene) (PEDT) as the active component. The pumping effect originated from an ac potential applied to an asymmetric array of interdigitated electrodes. The PEDT electrodes were fabricated using optical lithography and reactive ion etching, and dimensions down to 2 µm could be successfully realized. The channel system was made from a flexible thermoplastic polyurethane. The chosen polyurethane exhibited good sealing without the possible contamination issues of silicones, adequate wetting without plasma treatment, and has the potential for mass production, e.g., by injection moulding. The assembled micropump showed a pumping speed of 150 µm s-1 at a frequency of 10 kHz and an amplitude of 5 V. Higher potentials resulted in permanent damage to the pump electrodes. Encapsulation of the conducting polymer electrodes by an insulating polymer layer prevented electrode break-down at the cost of pumping efficiency. Continuous pumping for 40 min at 20 µm s-1 without detectable pump degradation was demonstrated in this configuration.

Hansen, Thomas Steen; West, Keld; Hassager, Ole; Larsen, Niels B.

2007-05-01

362

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 photo...

Wang, Guang-feng; Tao, Xiao-ming; Xin, John H.; Fei, Bin

2009-01-01

363

Highly Transparent Conducting Polymer Top Contacts for Future III–Nitride Based Single Photon Emitters  

Science.gov (United States)

In this paper we report on a simple conductive polymer based contacting technology for III–nitride based nanostructures with respect to the electrical operation within the telecommunication wavelength range. Singularly addressable InN/GaN pyramidal nanostructures were selectively grown by metalorganic vapour phase epitaxy (MOVPE) and subsequently integrated into a high-frequency device layout for future ultrafast electro-optical operation. The employment of the p-conducting polymer poly(3,4-ethylenedioxythiophene)–poly(styrene sulfonate) (PEDOT:PSS) is found to increase the light transmittance up to 89% at a wavelength of 1550 nm compared to 72% in the case of a conventional Ni/Au thin layer top contact. DC measurements using a quasi operation mode for 1000 h reveal no degradation and only a moderate increase of the dark currents. Thus, conducting polymer technology shows tremendous potential for future highly efficient and reliable room temperature operation of nitride based single photon emitters (SPEs).

Riess, Sally; Mikulics, Martin; Winden, Andreas; Adam, Roman; Marso, Michel; Grützmacher, Detlev; Hardtdegen, Hilde

2013-08-01

364

Individually addressable crystalline conducting polymer nanowires in a microelectrode sensor array  

International Nuclear Information System (INIS)

An efficient, site-specific and scalable approach has been developed to produce high-quality and individually addressable conducting polymer nanowire electrode junctions (CPNEJs) in a parallel-oriented array. Polypyrrole and PEDOT conducting polymer nanowires (CPNWs) with uniform diameters (ca. 60-150 nm) were introduced into the desired electrode junctions in a precise manner by performing a three-step constant-current electrochemical process at a low current density and a low concentration of monomers. A low scan rate, cyclic voltammetric method was also employed and gave similar results. These CPNEJ arrays function as a miniaturized sensor for the parallel and real-time detection of gas and organic vapour. The electrochemical approaches utilized allow the conducting polymer chains to self-organize in the CPNWs to form novel polycrystalline structures, observed by high resolution TEM. The weak diffraction rings at 4.88 A and 4.60 A were observed for PEDOT and polypyrrole CPNWs, respectively

2007-10-24

365

Phase stability of Li-ion conductive, ternary solid polymer electrolytes  

International Nuclear Information System (INIS)

The chemical–physical properties of a ternary solid polymer electrolyte (SPE) system consisting of poly(ethylene oxide) and two salts, namely lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and the ionic liquid N-methyl-N-butyl-pyrrolidinium bis(trifluoromethanesulfonyl)imide (Pyr14TFSI), are reported in this work. The ternary phase diagram shows the composition limits of the thermodynamically stabilized amorphous phase where the polymer electrolyte achieved the maximum conductivity. The important conductivity threshold of 10?3 S cm?1 at 40 °C is exceeded for these compositions. Two reasons for the high conductivity are identified; the decreased overall coordination to the Li+-ion and a Tg as low as ?67 °C. Also presented is the thermal stability characterization of such polymer electrolytes. The amorphous phase seems to be thermodynamically unfavored; however, the recrystallization process is slow

2013-12-15

366

Ultraviolet light responses in photovoltaic properties of TiO2/conducting polymer heterostructure devices  

International Nuclear Information System (INIS)

Photovoltaic properties of heterostructure devices of titanium oxide (TiO2) and conducting polymer thin films have been studied. Normal photovoltaic properties were stably observed upon the visible light irradiation of the wavelength range corresponding to the absorption of a conducting polymer, and unique photovoltaic properties were also observed upon the ultraviolet (UV) light irradiation of the wavelength range corresponding to the absorption of TiO2. UV light irradiation caused marked increases in the short-circuit current at the visible-wavelength range and in the open-circuit voltage. These properties have been discussed by considering the enhancement of the built-in field which originates from the hole accumulation caused by the trap levels in the TiO2 layer or TiO2/conducting polymer interface

2004-10-11

367

Proton conducting, composite sulfonated polymer membrane for medium temperature and low relative humidity fuel cells  

Science.gov (United States)

Inorganic-organic composite membranes are fabricated using zirconium acetylacetonate nanoparticles and biphenol-based sulfonated poly(arylene ether sulfone) as an inorganic, proton conducting nanomaterial and a polymer matrix, respectively. An amphiphilic surfactant (Pluronic®) induces distribution of the inorganic nanoparticles over the entire polymer membrane. The composite membranes are thermally stable up to 200 °C. Zirconium acetylacetonate improves inter-chain interactions and the robustness of polymer membranes resulting in excellent membrane mechanical properties. In addition, composite membranes show outstanding proton conductivity compared to that of the pristine membrane at medium temperatures (80-120 °C) and low relative humidity (conducting site and/or medium. Therefore, the composite membranes significantly outperform the pristine membrane in fuel cell performance tests at medium temperatures and low relative humidity.

Shin, Dong Won; Kang, Na Rae; Lee, Kang Hyuck; Cho, Doo Hee; Kim, Ji Hoon; Lee, Won Hyo; Lee, Young Moo

368

Synergistic Processes At Optically-Active Membrane-Protein, Conducting Polymer Interfaces  

Science.gov (United States)

Bacteriorhodopsin (bR), a protein existing in the halobacterial purple membrane serves as a light driven pump which sets up an electrochemical gradient and transports protons across the cell membrane. We have explored the synergetic processes at the conducting polymer/bR interface due to photoexcitation in presence of a voltage bias. Several interesting features in the photoelectric signal characteristics are observed from systems consisting of oriented-bR films on conducting polymer substrates. The possibility of changing the oxidation state of the polymer electrochemically is coupled to the optically-activated proton gradient in the bR side in this unique hybrid system. It was recently demonstrated that the internal conversion of the intermediate deprotonated M state of bR and the proton transfer/transport can be controlled by the electrochemical reactions at the adjacent poly(3,4-ethylenedioxythiophene) poly(styrene sulfonate) layer and leads to interesting device prospects in the process.^1,2 We generalize the principles involved by studying variety of mutant forms of bR and conducting polymers with different doping levels. The implications of coupling the biophysical events in bR with the electrochemical processes of the conducting polymer in terms of interesting wavelength- dependent photodiode features and photo-electrochemical transistor action will be discussed. 1. A. G. Manoj and K. S. Narayan, Appl. Phys. Lett., 83, 3614 (2003). 2. A. G. Manoj and K. S. Narayan , Biosens. and Bioelectr. J., 10, 967 (2004).

Narayan, K. S.

2005-03-01

369

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

International Nuclear Information System (INIS)

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

370

Conductivity behavior of very thin gold films ruptured by mass transport in photosensitive polymer film  

International Nuclear Information System (INIS)

We report on conductivity behavior of very thin gold layer deposited on a photosensitive polymer film. Under irradiation with light interference pattern, the azobenzene containing photosensitive polymer film undergoes deformation at which topography follows a distribution of intensity, resulting in the formation of a surface relief grating. This process is accompanied by a change in the shape of the polymer surface from flat to sinusoidal together with a corresponding increase in surface area. The gold layer placed above deforms along with the polymer and ruptures at a strain of 4%. The rupturing is spatially well defined, occurring at the topographic maxima and minima resulting in periodic cracks across the whole irradiated area. We have shown that this periodic micro-rupturing of a thin metal film has no significant impact on the electrical conductivity of the films. We suggest a model to explain this phenomenon and support this by additional experiments where the conductivity is measured in a process when a single nanoscopic scratch is formed with an AFM tip. Our results indicate that in flexible electronic materials consisting of a polymer support and an integrated metal circuit, nano- and micro cracks do not alter significantly the behavior of the conductivity unless the metal is disrupted completely

2013-12-16

371

Graphene-polyethylenedioxythiophene conducting polymer nanocomposite based supercapacitor  

Energy Technology Data Exchange (ETDEWEB)

Graphical abstract: Schematic diagrams of an electrochemical double layer type capacitor showing the charged (left) and discharged (right) states. Highlights: > The Graphene-PEDOT nanocomposite based smart coating has shown the excellent redox properties in acidic, organic electrolytes, which is promising for suprecapcitor application. > The electrochemical impedance studies have also been estimated which clearly indicates the high conductivity and less charge transfer resistance in the synthesized material. > The specific capacitance of 380F/g have been calculated for G-Pedot material, also it shows the columbic efficiency of 95% for 800 cycles, which tells the remarkable stability of synthesized material. - Abstract: We present here the synthesis, characterization and application of graphene (G)-polyethylenedioxythiophene (PEDOT) nanocomposites as electrode material for supercapacitor applications. The G-PEDOT nanocomposite was synthesized using a chemical oxidative polymerization technique, and characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, FTIR spectroscopy, X-ray-diffraction, electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV) techniques. The electrochemical charge/discharge characteristics of G-PEDOT nanocomposites were investigated in different electrolytic media, and the specific discharge capacitance was estimated to be 374 Farad/gram (F/gm). This manuscript presents the capacitance studies on supercapacitor G-PEDOT electrode with respect to stability of material, specific capacitance, electrical conductivity and specific charge/discharge properties of the supercapacitor electrodes. Our study has revealed that the G-PEDOT nanocomposite could be a transformable and viable electrode material for supercapacitor applications.

Alvi, Farah [Department of Electrical Engineering, University of South Florida, ENB 118, Tampa, FL 33620-5350 (United States); Ram, Manoj K., E-mail: mkram@mail.usf.edu [Clean Energy Research center (CERC), University of South Florida, ENB 118, Tampa, FL 33620-5350 (United States); Basnayaka, Punya A. [Department of Mechanical Engineering, University of South Florida, ENB 118, Tampa, FL 33620-5350 (United States); Stefanakos, Elias [Department of Electrical Engineering, University of South Florida, ENB 118, Tampa, FL 33620-5350 (United States); Goswami, Yogi [Department of Chemical and Biomedical Engineering, University of South Florida, ENB 118, Tampa, FL 33620-5350 (United States); Kumar, Ashok [Department of Mechanical Engineering, University of South Florida, ENB 118, Tampa, FL 33620-5350 (United States); Clean Energy Research center (CERC), University of South Florida, ENB 118, Tampa, FL 33620-5350 (United States)

2011-10-30

372

Graphene-polyethylenedioxythiophene conducting polymer nanocomposite based supercapacitor  

International Nuclear Information System (INIS)

Graphical abstract: Schematic diagrams of an electrochemical double layer type capacitor showing the charged (left) and discharged (right) states. Highlights: ? The Graphene-PEDOT nanocomposite based smart coating has shown the excellent redox properties in acidic, organic electrolytes, which is promising for suprecapcitor application. ? The electrochemical impedance studies have also been estimated which clearly indicates the high conductivity and less charge transfer resistance in the synthesized material. ? The specific capacitance of 380F/g have been calculated for G-Pedot material, also it shows the columbic efficiency of 95% for 800 cycles, which tells the remarkable stability of synthesized material. - Abstract: We present here the synthesis, characterization and application of graphene (G)-polyethylenedioxythiophene (PEDOT) nanocomposites as electrode material for supercapacitor applications. The G-PEDOT nanocomposite was synthesized using a chemical oxidative polymerization technique, and characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, FTIR spectroscopy, X-ray-diffraction, electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV) techniques. The electrochemical charge/discharge characteristics of G-PEDOT nanocomposites were investigated in different electrolytic media, and the specific discharge capacitance was estimated to be 374 Farad/gram (F/gm). This manuscript presents the capacitance studies on supercapacitor G-PEDOT electrode with respect to stability of material, specific capacitance, electrical conductivity and specific charge/discharge properties of the supercapacitor electrodes. Our study has revealed that the G-PEDOT nanocomposite could be a transformable and viable electrode material for supercapacitor applications.

2011-10-30

373

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

374

Polyethylene oxide-polytetrahydrofurane-PEDOT conducting interpenetrating polymer networks for high speed actuators  

Science.gov (United States)

In recent years, numerous studies on electro-active polymer (EAP) actuators have been reported. One promising technology is the elaboration of electronic conducting polymer-based actuators with interpenetrating polymer network (IPNs) architecture. In this study, the synthesis and characterisation of conducting IPNs for actuator applications is described. The IPNs are synthesised from polyethylene oxide (PEO) and polytetrahydrofurane (PTHF) networks in which the conducting polymer (poly(3,4-ethylenedioxythiophene)) is incorporated. In a first step, PEO/PTHF IPNs were prepared via an 'in situ' process using poly(ethylene glycol) methacrylate and dimethacrylate and hydroxytelechelic PTHF as starting materials. The IPN mechanical properties were examined by DMA and tensile strength tests. N-ethylmethylimidazolium bis(trifluoromethanesulfonyl)imide (EMITFSI) swollen PEO/PTHF IPNs show ionic conductivities up to 10-3 S cm-1 at 30 °C. In a second step, the conducting IPN actuators were prepared by oxidative polymerisation of 3,4-ethylenedioxithiophene (EDOT) using FeCl3 as an oxidising agent within the PEO/PTHF IPN host matrix. The frequency response performance of the bending conducting IPN actuator was then evaluated. The resulting actuator exhibits a mechanical resonance frequency of up to 125 Hz with 0.75% strain for an applied potential of ± 5 V.

Plesse, C.; Khaldi, A.; Wang, Q.; Cattan, E.; Teyssié, D.; Chevrot, C.; Vidal, F.

2011-12-01

375

Polyethylene oxide–polytetrahydrofurane–PEDOT conducting interpenetrating polymer networks for high speed actuators  

International Nuclear Information System (INIS)

In recent years, numerous studies on electro-active polymer (EAP) actuators have been reported. One promising technology is the elaboration of electronic conducting polymer-based actuators with interpenetrating polymer network (IPNs) architecture. In this study, the synthesis and characterisation of conducting IPNs for actuator applications is described. The IPNs are synthesised from polyethylene oxide (PEO) and polytetrahydrofurane (PTHF) networks in which the conducting polymer (poly(3,4-ethylenedioxythiophene)) is incorporated. In a first step, PEO/PTHF IPNs were prepared via an 'in situ' process using poly(ethylene glycol) methacrylate and dimethacrylate and hydroxytelechelic PTHF as starting materials. The IPN mechanical properties were examined by DMA and tensile strength tests. N-ethylmethylimidazolium bis(trifluoromethanesulfonyl)imide (EMITFSI) swollen PEO/PTHF IPNs show ionic conductivities up to 10?3 S cm?1 at 30?°C. In a second step, the conducting IPN actuators were prepared by oxidative polymerisation of 3,4-ethylenedioxithiophene (EDOT) using FeCl3 as an oxidising agent within the PEO/PTHF IPN host matrix. The frequency response performance of the bending conducting IPN actuator was then evaluated. The resulting actuator exhibits a mechanical resonance frequency of up to 125 Hz with 0.75% strain for an applied potential of ± 5 V

2011-12-01

376

Novel conducting polymer-heteropoly acid hybrid material for artificial photosynthetic membranes.  

Science.gov (United States)

Artificial photosynthetic (AP) approaches to convert and store solar energy will require membranes capable of conducting both ions and electrons while remaining relatively transparent and chemically stable. A new approach is applied herein involving previously described in situ chemical polymerization of electronically conducting poly(3,4-ethylenedioxythiophene) (PEDOT) in the presence of proton conducting heteropoly acid (HPA) phosphomolybdic acid (PMA). The electrochemical behaviour of the PEDOT/PMA hybrid material was investigated and it was found that the conducting polymer (CP) is susceptible to irreversible oxidative processes at potentials where water is oxidized. This will be problematic in AP devices should the process occur in very close proximity to a conducting polymer-based membrane. It was found that PEDOT grants the system good electrical performance in terms of conductivity and stability over a large pH window; however, the presence of PMA was not found to provide sufficient proton conductivity. This was addressed in an additional study by tuning the ionic (and in turn, electronic) conductivity in creating composites with the proton-permselective polymer Nafion. It was found that a material of this nature with near-equal conductivity for optimal chemical conversion efficiency will consist of roughly three parts Nafion and one part PEDOT/PMA. PMID:21384827

McDonald, Michael B; Freund, Michael S

2011-04-01

377

12-Tungstosilicic acid doped polyethylene oxide as a proton conducting polymer electrolyte  

International Nuclear Information System (INIS)

Polymeric proton electrolytes based on the composite of 12-tungstosilicic acid (12-TSA) and polyethylene oxide (PEO) have been prepared. X-ray diffraction (XRD) and infrared spectroscopy indicate that 12-TSA in the composite is complexed with the polymer to form a new compound. The proton conductivity of the composite polymer electrolyte depends on the concentration of the 12-TSA, the relative humidity and the temperature. The highest conductivity at room temperature has been found to be 6.3x10-2 S cm-1 for the composite with an [H+]/[EO] mole ratio of 0.025

2003-05-26

378

Ionic conduction properties of PVDF-HFP type gel polymer electrolytes with lithium imide salts  

Energy Technology Data Exchange (ETDEWEB)

Conduction properties of gel polymer electrolytes composed of lithium imide salts, LiN(CF{sub 3}SO{sub 2}){sub 2}, LiN(C{sub 2}F{sub 5}SO{sub 2}){sub 2}, and PVDF-HFP copolymer were investigated using the pulsed-field gradient NMR and complex impedance techniques. The diffusion coefficients of the gel decreased with an increase in the polymer fraction in the gel. Carrier concentration exhibited 3 orders of magnitude variation in the fraction change in polymer from 80% to 20%. These results suggest that the polymer interacts with the electrolyte to affect the carrier concentration and mobility of the gel electrolytes. The interactive effect of polymer would be detected in the measurements of spin-lattice relaxation time (T{sub 1}). The deviation of the symmetric curve of the temperature dependence of T{sub 1} could be divided into two components, one was consistent with the component of solution and independent of the polymer fraction and the other depended on the polymer fraction in the gel.

Saito, Yuria; Kataoka, Hiroshi; Capiglia, C.; Yamamoto, Hitoshi

2000-03-09

379

Preparation and characterization of novel nanocomposites of WS2 nanotubes and polyfluorene conductive polymer  

International Nuclear Information System (INIS)

Tungsten disulfide (WS2) nanotubes are used to prepare polymer nanocomposites, similarly to other metal dichalcogenide materials, to improve lubricating and/or mechanical properties. In order to explore the possibility to extend these advantages to conductive polymers we realized new nanocomposites of WS2 nanotubes and polyfluorene conjugated polymer (WS2/PFO). The nanocomposites were prepared from solution processing at several nanotubes concentrations. The morphological and structural analyses by SEM and XRD proved that the density of nanotubes within the polymer increased according to the preparation conditions. The successful incorporation of WS2 nanotubes was also evidenced by UV-Vis absorbance spectroscopy. The WS2/PFO nanocomposites were tested in light emitting devices at relatively big load of nanotubes realizing a new class of devices with promising improved mechanical and thermal properties without affecting substantially the device optoelectronic performances. (copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

2013-11-01

380

Electrochemical Deposition of Nanostructured Conducting Polymer Coatings on Neural Prosthetic Devices  

Science.gov (United States)

Micromachined neural prosthetic devices facilitate the functional stimulation of and recording from the central nervous system (CNS). These devices have been fabricated to consist of silicon shanks that have gold or iridium sites along their surface. Our goal is to improve the biocompatibility and long-term performance of the neural prosthetic probes when they are implanted chronically in the brain. In our most recent efforts we have established that electrochemical polymerization can be used to deposit fuzzy coatings of conducting polymers specifically on the electrode sites. For neural prosthetic devices that are intended for long term implantation, we need to develop surfaces that provide intimate contact and promote efficient signal transport at the interface of the microelectrode array and brain tissue. We have developed methods to rapidly and reliably fabricate nanostructured conducting polymer coatings on the electrode probes using templated and surfactant-mediated techniques. Conducting polymer nanomushrooms and nanohairs of polypyrrole (PPy) were electrochemically polymerized onto the functional sites of neural probes by using either nanoporous block copolymers thin films, "track-etched" polycarbonate films or anodic aluminium oxide membranes as templates. Nanofibers of conducting polymers have also been successfully obtained by polymerizations in the presence of surfactants. The influence of current density, monomer concentration, surfactant concentration, and deposition charge on the thickness and morphology of the nanostructured conducting polymer coatings has been studied by optical, scanned probe, scanning electron and transmission electron microscopy. As compared with the normal nodular morphology of polypyrrole, the nanostructured morphologies grown from the neural electrode result in fuzzy coatings with extremely high surface area. The electrical properties of the polymer coatings were studied by Impedance Spectroscopy (IS) and Cyclic Voltammetry (CV). The significant drop in impedance in magnitude and phase angle is consistent with an increase of the surface area due to the roughened surface morphology.

Yang, Junyan; Martin, David

2003-03-01

 
 
 
 
381

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

382

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

Science.gov (United States)

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.

Vaddiraju, Sreeram; Gleason, Karen K.

2010-03-01

383

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

Science.gov (United States)

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 article 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 behavior 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. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 2743-2754, 2014. PMID:24027227

Baek, Sungchul; Green, Rylie A; Poole-Warren, Laura A

2014-08-01

384

Controlled Aloin Release from Crosslinked Polyacrylamide Hydrogels: Effects of Mesh Size, Electric Field Strength and a Conductive Polymer  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The aim of this paper is to investigate the effects of hydrogel mesh size, a conductive polymer, and electric field strength on controlled drug delivery phenomena using drug-loaded polyacrylamide hydrogels prepared at various crosslinking ratios both with and without a conductive polymer system. Poly(p-phenylene vinylene), PPV, as the model conductive polymer, was used to study its ability to control aloin released from aloin-doped poly(p-phenylene vinylene)/polyacrylamide hydrogel (aloin-dop...

Sumonman Niamlang; Tawansorn Buranut; Amornrat Niansiri; Anuvat Sirivat

2013-01-01

385

Conductivity enhancement via chemical modification of chitosan based green polymer electrolyte  

International Nuclear Information System (INIS)

The potential of carboxymethyl chitosan as a green polymer electrolyte has been explored. Chitosan produced from partial deacetylation of chitin was reacted with monochloroacetic acid to form carboxymethyl chitosan. A green polymer electrolyte based chitosan and carboxymethyl chitosan was prepared by solution-casting technique. The powder and films were characterized by reflection Fourier transform infrared (ATR-FTIR) spectroscopy, 1H nuclear magnetic resonance, elemental analysis and X-ray diffraction, electrochemical impedance spectroscopy, and scanning electron microscopy. The shift of wavenumber that represents hydroxyl and amine stretching confirmed the polymer solvent complex formation. The XRD spectra results show that chemical modification of chitosan has improved amorphous properties of chitosan. The ionic conductivity was found to increase by two magnitudes higher with the chemical modification of chitosan. The highest conductivity achieved was 3.6 × 10?6 S cm?1 for carboxymethyl chitosan at room temperature and 3.7 × 10?4 S cm?1 at 60 °C

2013-03-01

386

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

2012-01-01

387

Synthesis and Characterization of Conducting Elastomers Based on Interpenetrated C60-Derived Polymer Networks  

Canada Institute for Scientific and Technical Information (Canada)

Highly stretchable elastomers embedded with a thin conducting polyaniline layer. A processing technique was demonstrated or the fabrication of interpenetrating conductive polyaniline networks at the near-surface region of fullerenol hypercrosslinked poly (urethane ether) elastomer films. The resulting conductive elastomer film is highly stretchable and exhibits appreciable conductivity in the incorporated, doped polyaniline layer without deteriorating the elasticity and tensile strength of the bulk supporting polymer. Conductive polymers designed by this synthetic method exhibit increased conductivity even upon elastomer elongation by 500% of original length. Hysteresis was observed; however, a high reversibility of the strain-dependent resistivity was evident, thus indicating no further deterioration in the strain-dependent resistance. Also, full compressibility of the conductive C60-PU-PANI elastomer with a nearly constant pressure-dependent resistance was observed from 10 psi to 90 psi. Synthesis of octadecahydroxylated C70. Novel hydrophilic ?70Z polymers were synthesized in a reaction involving oxidative sulfation of the C70 molecules induced by H2SO4-SO3. Addition of P2O5 or SeO2 achieved modulation of the sulfation rate til high yield (72%). MALDI-TOF mass spectrum of the ?70Z fullerenols indicate octadecahydroxyfullerenes containing 11 hydroxy addends per C70 cage, which correlates the structure of its sulfated precursor as noncyclosulfated ?70Z fullerene, C70(SO4)9.

1998-01-01

388

Layer-by-layer assembled oxidative films as general platform for electrodeless formation of conducting polymers.  

Science.gov (United States)

Fabrication of precisely tailored layers of conductive polymers in thin film assemblies is an attractive extension of the layer-by-layer technique. This approach provides tools for fabricating thin films with customized optical and electrical properties. In this paper, we study inorganic layer-by-layer assembled films prepared using polyphosphate and cerium(IV). It is shown that these multilayers can oxidize certain monomers from the adjacent aqueous solution to produce conducting polymer layers. We studied the thermodynamic factors that allow the aforementioned autopolymerization. A five bilayer polyphosphate/cerium(IV) film was shown to possess high oxidative power in acidic solutions. It was found that the polymerization of pyrrole, aniline and 3,4-ethylenedioxythiophene in contact with the redox active multilayer is thermodynamically favored. The rate of polymer formation and the thickness of the conducting film could be controlled by the concentration of the monomer in solution and the number of cerium/polyphosphate bilayers in the oxidative film. The oxidative polymerization of pyrrole was unambiguously recognized on UV-vis spectra with characteristic reduction and oxidation bands. The film formation was not restricted by charge diffusion and the reaction formally followed first-order kinetics. The results suggest that the reaction takes place effectively within the whole pre-existing polypyrrole film and it continues until all oxidant in the film was used. The spectral changes that are characteristic for conducting polypyrrole are shown on spectroelectrochemical analysis of the films indicating that cationic (polaron) and dicationic (bipolaron) species are involved in the redox processes of the film. The functional polymer films formed are found to be electroactive and conducting. Therefore, they fully resemble of conducting polymer films prepared using traditional electropolymerization. PMID:24456025

Salomäki, Mikko; Myllymäki, Ossi; Hätönen, Minna; Savolainen, Juho; Lukkari, Jukka

2014-02-26

389

Microfabrication of a Polymer Based Bi-Conductive Membrane for a Polymer Electrolyte Membrane Fuel Cell  

Science.gov (United States)

This paper reports a novel fabrication process of a high active area ratio bi-conductive membrane for PEMFCs. The fabricated device is a 50?m thick flexible polyimide based membrane that integrates for the first time lateral electrical conductive layers on both sides with a through ionic conductive path. With the use of thermo-conductive rubber as a bonding agent allowing a quick-flip process, five configurations of double-sided multilayer metal sputtering on polyimide were tested. An approach for filling through pores in the membrane with the ionic conductor (Nafion) with a temporary reservoir was also developed. The development of these new processes allowed to fabricate a membrane with 50?m wide holes filled with ionic conductor with double-sided electrical conductive layers.

Hamel, S.; Tsukamoto, T.; Tanaka, S.; Fréchette, L. G.

2013-12-01

390

Lithium ion conductivity of gel polymer electrolytes containing insoluble lithium tetrakis(pentafluorobenzenethiolato) borate  

Energy Technology Data Exchange (ETDEWEB)

Lithium ion conducting gel polymer electrolytes composed of insoluble lithium tetrakis(pentafluorobenzenethiolato) borate (LiTPSB), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and ethylene carbonate-propylene carbonate mixed solvent (EC-PC) were prepared and their ionic conductivities and electrochemical stabilities were investigated. Ionic conductivity was largely dependent on the contents of EC-PC and LiTPSB. Gel polymer electrolyte containing optimized content of 50 (LiTPSB)-50 (PVDF-HFP/EC-PC (13:87wt.%)) exhibited ionic conductivity of 4x10{sup -4}Scm{sup -1} at 30{sup o}C, lithium ion transference number of 0.33 and anodic oxidation potential of 4.2V. (author)

Aoki, Takahiro; Ohta, Takayuki; Fujinami, Tatsuo [Department of Materials Science and Chemical Engineering, Faculty of Engineering, Shizuoka University, 3-5-1, Johoku, Hamamatsu 432-8561 (Japan)

2006-06-01

391

Radiation chemistry as an alternative way for the synthesis of PEDOT conducting Polymers under “soft” Conditions  

International Nuclear Information System (INIS)

Synthesis of conducting PEDOT is achieved through an original soft alternative way: radiolysis of aerated aqueous solutions of EDOT in the absence of any external chemical initiators. The oxidation of EDOT monomers is shown to be initiated by HO. hydroxyl radicals produced by water radiolysis. A recurrent step-by-step oxidation process leads to self-assembled hydrophilic PEDOT polymers which are evidenced in solution by cryo-TEM and after centrifugation and deposition by AFM and ATR-FTIR techniques. Optical and conducting properties of radiosynthesized PEDOT-containing layers, which are respectively evaluated by UV-visible absorption spectroscopy and by cyclic voltammetry, are found to be close to those of usually electrosynthesized PEDOT layers. Highlights: ? ?-radiolysis is used as a “soft” alternative way for synthesizing conducting polymers. ? Starting from EDOT monomers, PEDOT polymers are produced. ? A mechanistic study of EDOT oxidation is considered. ? Chemical and structural characterizations of PEDOT are made. ? Their optical and conducting properties are compared to those of electrochemically synthesized PEDOT polymers.

2013-01-01

392

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

393

Conductivity studies of LiCF{sub 3}SO{sub 3} doped PVA: PVdF blend polymer electrolyte  

Energy Technology Data Exchange (ETDEWEB)

Different composition of lithium ion conducting PVA: PVdF: Lithium triflate (LiCF{sub 3}SO{sub 3}) polymer electrolytes have been prepared by solution casting technique. Dielectric and conductivity studies have been carried out for the prepared samples. The addition of salt into the polymer matrix increases the ionic conductivity of blend polymer electrolytes. The conductivity analysis reveals 80PVA: 20PVdF: 15LiCF{sub 3}SO{sub 3} polymer electrolyte exhibits the maximum ionic conductivity of 2.7×10{sup ?3} S cm{sup ?1} at 303 K. The temperature dependence of ionic conductivity for all the composition of PVA: PVdF: LiCF{sub 3}SO{sub 3} polymer films obey Arrhenius relation. Low activation energy has been obtained for highest conducting sample. The dielectric spectra show absolute ?-relaxation peak.

Tamilselvi, P.; Hema, M., E-mail: mhema2006@gmail.com

2014-03-15

394

Conductivity studies of LiCF3SO3 doped PVA: PVdF blend polymer electrolyte  

International Nuclear Information System (INIS)

Different composition of lithium ion conducting PVA: PVdF: Lithium triflate (LiCF3SO3) polymer electrolytes have been prepared by solution casting technique. Dielectric and conductivity studies have been carried out for the prepared samples. The addition of salt into the polymer matrix increases the ionic conductivity of blend polymer electrolytes. The conductivity analysis reveals 80PVA: 20PVdF: 15LiCF3SO3 polymer electrolyte exhibits the maximum ionic conductivity of 2.7×10?3 S cm?1 at 303 K. The temperature dependence of ionic conductivity for all the composition of PVA: PVdF: LiCF3SO3 polymer films obey Arrhenius relation. Low activation energy has been obtained for highest conducting sample. The dielectric spectra show absolute ?-relaxation peak

2014-03-15

395

Influence of humidity and crystallization time on the conductivity of nanoparticle-filled solid polymer electrolytes  

Science.gov (United States)

The purpose of this study is to investigate two conditions that influence the conductivity of solid polymer electrolytes [SPEs]: humidity and crystallinity. SPEs cannot currently be used in solid-state lithium ion batteries because low room-temperature conductivity precludes effective application. Many modifications have been made to improve the conductivity; however, conductivity results vary widely for the same system investigated within different studies. One explanation is that SPE conductivity is extremely sensitive to experimental conditions which are often not reported. We investigate the consequence of humidity on conductivity, and the time at which conductivity is measured following sample preparation. Specifically, we choose nanoparticle-filled SPEs as an example to demonstrate that various conclusions can be made regarding the influence of nanoparticles on conductivity, depending on the experimental conditions.

Fullerton, Susan; Maranas, Janna

2007-03-01