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1

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

2

Reversible conductance switching characteristics in a polymer-In2O3 nanocrystals junction  

Science.gov (United States)

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.

Kim, Jongmin; Lee, Dong Uk; Jo, Yongcheol; Han, J.; Kim, H. S.; Inamdar, A. I.; Jung, W.; Im, Hyunsik; Kim, Eun Kyu

2014-06-01

3

Semiconductor-nanocrystal/conjugated polymer thin films  

Energy Technology Data Exchange (ETDEWEB)

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

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

2010-08-17

4

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

5

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

6

Conducting polymer materials  

Directory of Open Access Journals (Sweden)

Full Text Available Conducting polymers represent a very interesting group of polymer materials Investigation of the synthesis, structure and properties of these materials has been the subject of considerable research efforts in the last twenty years. A short presentating of newer results obtained by investigating of the synthesis, structure and properties of two basic groups of conducting polymers: a conducting polymers the conductivity of which is the result of their molecular structure, and b conducting polymer composites (EPC, is given in this paper. The applications and future development of this group of polymer materials is also discussed.

Jovanovi? Slobodan M.

2003-01-01

7

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

8

'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

9

Assembling a lasing hybrid material with supramolecular polymers and nanocrystals  

Science.gov (United States)

The combination of bottom-up and top-down processes to organize nanophases in hybrid materials is a key strategy to create functional materials. We found that oxide and sulphide nanocrystals become spontaneously dispersed in organic media during the self-assembly of nanoribbon supramolecular polymers. These nanoribbon polymers form by self-assembly of dendron rodcoil molecules, which contain three molecular blocks with dendritic, rod-like, and coil-like architectures. In an electric field these supramolecular assemblies carrying bound nanocrystals migrate to the positive electrode in an etched channel and align in the field. In the system containing ZnO nanocrystals as the inorganic component, both phases are oriented in the hybrid material forming an ultraviolet lasing medium with a lower threshold relative to pure ZnO nanocrystals.

Li, Leiming; Beniash, Elia; Zubarev, Eugene R.; Xiang, Wanghua; Rabatic, Bryan M.; Zhang, Guizhong; Stupp, Samuel I.

2003-10-01

10

Semiconductor nanocrystals in photoconductive polymers: Charge generation and charge transport  

Energy Technology Data Exchange (ETDEWEB)

A new class of photoconductive polymer composites, based on semiconductor nanocrystals (clusters) and carder-transporting polymers, have been developed. These materials are interesting for their potentials in laser printing, imaging, and photorefractives. We will describe material synthesis, charge transport and charge generation mechanisms. In particular, a model of field-dependent charge generation and separation in nonpolar media (e.g. polymers) will be discussed.

Wang, Ying; Herron, Norman; Suna, A. [Du Pont Co., Wilmington, DE (United States)

1996-10-01

11

Transient terahertz conductivity in photoexcited silicon nanocrystal films  

DEFF Research Database (Denmark)

Time-resolved terahertz spectroscopy is used to probe ultrafast carrier dynamics and terahertz conductivity in photoexcited thin films of silicon nanocrystals, polynanocrystalline silicon, and epitaxial silicon-on-sapphire. We show that a Drude-Smith model provides an excellent fit to the observed transient terahertz conductivity in all of our samples, revealing a transition from a Drude-like response with low carrier backscatter in bulk silicon-on-sapphire to a non-Drude-like, localized behavior with high carrier backscatter in the silicon nanocrystal films. Evidence for long-range conduction between nanocrystals is observed, and we show that the photoconductive lifetime of the silicon nanocrystals is dominated by trapping at Si/SiO2 interface states.

Cooke, David; MacDonald, A. N.

2006-01-01

12

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

13

Conjugated polymer/nanocrystal nanocomposites for renewable energy applications in photovoltaics and photocatalysis.  

Science.gov (United States)

Conjugated polymer/nanocrystal composites have attracted much attention for use in renewable energy applications because of their versatile and synergistic optical and electronic properties. Upon absorbing photons, charge separation occurs in the nanocrystals, generating electrons and holes for photocurrent flow or reduction/oxidation (redox) reactions under proper conditions. Incorporating these nanocrystals into conjugated polymers can complement the visible light absorption range of the polymers for photovoltaics applications or allow the polymers to sensitize or immobilize the nanocrystals for photocatalysis. Here, the current developments of conjugated polymer/nanocrystal nanocomposites for bulk heterojunction-type photovoltaics incorporating Cd- and Pb-based nanocrystals or quantum dots are reviewed. The effects of manipulating the organic ligands and the concentration of the nanocrystal precursor, critical factors that affect the shape and aggregation of the nanocrystals, are also discussed. In the conclusion, the mechanisms through which conjugated polymers can sensitize semiconductor nanocrystals (TiO2 , ZnO) to ensure efficient charge separation, as well as how they can support immobilized nanocrystals for use in photocatalysis, are addressed. PMID:25074641

Su, Yu-Wei; Lin, Wei-Hao; Hsu, Yung-Jung; Wei, Kung-Hwa

2014-11-01

14

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

15

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

16

Conducting polymer 3D microelectrodes  

DEFF Research Database (Denmark)

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

Sasso, Luigi; Vazquez, Patricia

2010-01-01

17

Culture experiments on conductive polymers  

Science.gov (United States)

Fibroblast L929 and myoblast C2C12 cells of the mouse connective tissue origin were sown on the surface of conductive polymer films (polypyrrole, PPy and poly(3,4-ethylenedioxythiophene), PEDOT) in the cell culture medium, and the proliferative process of these cells was observed. Without changing the form, fibroblast L929 and myoblast C2C12 cells were observed to proliferate almost similarly to the cell which cultured on a dish on the market and to maintain compatibility. In other word, it has been understood these two kinds of conductive polymers used in this study, the PEDOT films maintain the secretion function of the cell cultured on the surface of these polymers. Therefore, the PPy- and the PEDOT-coated electrode suggested the possibility usable as a nerve stimulation electrode with biocompatibility, because these polymers were effective to culture the cell.

Onoda, Mitsuyoshi

2012-04-01

18

Culture experiments on conductive polymers  

International Nuclear Information System (INIS)

Fibroblast L929 and myoblast C2C12 cells of the mouse connective tissue origin were sown on the surface of conductive polymer films (polypyrrole, PPy and poly(3,4-ethylenedioxythiophene), PEDOT) in the cell culture medium, and the proliferative process of these cells was observed. Without changing the form, fibroblast L929 and myoblast C2C12 cells were observed to proliferate almost similarly to the cell which cultured on a dish on the market and to maintain compatibility. In other word, it has been understood these two kinds of conductive polymers used in this study, the PEDOT films maintain the secretion function of the cell cultured on the surface of these polymers. Therefore, the PPy- and the PEDOT-coated electrode suggested the possibility usable as a nerve stimulation electrode with biocompatibility, because these polymers were effective to culture the cell.

19

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

20

The workshop on conductive polymers: Final report  

Energy Technology Data Exchange (ETDEWEB)

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

1985-01-01

 
 
 
 
21

Creating nanocrystals in amorphous silicon using a conductive tip.  

Science.gov (United States)

Field-enhanced metal-induced solid phase crystallization (FE-MISPC) of amorphous silicon is scaled down to nanoscale dimensions by using a sharp conductive tip in atomic force microscopy (AFM) as one of the electrodes. The room temperature process is driven by the electrical current of the order of 100 pA between the tip and the bottom nickel electrode. This results in energy transfer rates of 30-50 nJ s(-1). Amplitude of the current is limited by a MOSFET transistor to avoid electrical discharge from parasitic parallel capacitance. Limiting the current amplitude and control of the transferred energy (approximately 100 nJ) enables formation of silicon crystals with dimensions smaller than 100 nm in the amorphous film. Formation of the nanocrystals is localized by the AFM tip position. The presence of nanocrystals is detected by current-sensing AFM and independently corroborated by micro-Raman spectroscopy. The nanocrystal formation is discussed based on a model considering microscopic electrical contact, thermodynamics of crystallization and silicide formation. PMID:19417314

Rezek, B; Sípek, E; Ledinský, M; Stuchlík, J; Vetushka, A; Kocka, J

2009-01-28

22

Electrically conductive polymer concrete coatings  

Science.gov (United States)

A sprayable electrically conductive polymer concrete coating for vertical d 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 with 3.5 wt % modified bentonite clay. Such formulations apply evenly and provide enough rigidity for vertical or overhead structures so there is no drip or sag.

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

1990-01-01

23

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)

24

Nanodisco Balls: Control over Surface versus Core Loading of Diagnostically Active Nanocrystals into Polymer Nanoparticles.  

Science.gov (United States)

Nanoparticles of complex architectures can have unique properties. Self-assembly of spherical nanocrystals is a high yielding route to such systems. In this study, we report the self-assembly of a polymer and nanocrystals into aggregates, where the location of the nanocrystals can be controlled to be either at the surface or in the core. These nanospheres, when surface decorated with nanocrystals, resemble disco balls, thus the term nanodisco balls. We studied the mechanism of this surface loading phenomenon and found it to be Ca(2+) dependent. We also investigated whether excess phospholipids could prevent nanocrystal adherence. We found surface loading to occur with a variety of nanocrystal types including iron oxide nanoparticles, quantum dots, and nanophosphors, as well as sizes (10-30 nm) and shapes. Additionally, surface loading occurred over a range of polymer molecular weights (?30-3000 kDa) and phospholipid carbon tail length. We also show that nanocrystals remain diagnostically active after loading onto the polymer nanospheres, i.e., providing contrast in the case of magnetic resonance imaging for iron oxide nanoparticles and fluorescence for quantum dots. Last, we demonstrated that a fluorescently labeled protein model drug can be delivered by surface loaded nanospheres. We present a platform for contrast media delivery, with the unusual feature that the payload can be controllably localized to the core or the surface. PMID:25188401

Chhour, Peter; Gallo, Nicolas; Cheheltani, Rabee; Williams, Dewight; Al-Zaki, Ajlan; Paik, Taejong; Nichol, Jessica L; Tian, Zhicheng; Naha, Pratap C; Witschey, Walter R; Allcock, Harry R; Murray, Christopher B; Tsourkas, Andrew; Cormode, David P

2014-09-23

25

Rapid cytosolic delivery of luminescent nanocrystals in live cells with endosome-disrupting polymer colloids.  

Science.gov (United States)

Luminescent nanocrystals hold great potential for bioimaging because of their exceptional optical properties, but their use in live cells has been limited. When nanocrystals enter live cells, they are taken up in vesicles. This vesicular sequestration is persistent and precludes nanocrystals from reaching intracellular targets. Here, we describe a unique, cationic core-shell polymer colloid that translocates nanocrystals to the cytosol by disrupting endosomal membranes via a low-pH triggered mechanism. Confocal fluorescence microscopy and flow cytometry indicate that picomolar concentrations of quantum dots are sufficient for cytosolic labeling, with the process occurring within a few hours of incubation. We anticipate a host of advanced applications arising from efficient cytosolic delivery of nanocrystal imaging probes: from single particle tracking experiments to monitoring protein-protein interactions in live cells for extended periods. PMID:20831181

Bayles, Andrea R; Chahal, Harvind S; Chahal, Dev S; Goldbeck, Cheryl P; Cohen, Bruce E; Helms, Brett A

2010-10-13

26

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

27

Mixed ionic and electronic conductivity in polymers  

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

28

Nanostructured polymer membranes for proton conduction  

Science.gov (United States)

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

Balsara, Nitash Pervez; Park, Moon Jeong

2013-06-18

29

Interfacial Interactions in Polymer-Nanocrystal Thermoelectric Composites Provide a Novel Route for Power Factor Enhancement  

Science.gov (United States)

The highest performing thermoelectric materials currently available are fabricated via expensive high-temperature vacuum processing techniques. Recently, there has been an increasing interest in the thermoelectric properties of solution-processable materials, which have the potential to dramatically reduce module fabrication costs. These solution-processed materials however often exhibit poor transport properties, which undermines their competitive advantage over the more traditional expensive thermoelectric materials. Here, we present the thermoelectric transport properties of a new class of solution-processable conducting-polymer/inorganic composite materials as a function of nanocrystal loading. In the Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and Tellurium nanowire composite devices fabricated for this study, the thermoelectric performance of the composite exceeds that of either pure organic or inorganic component alone. This result suggests an interface-driven mechanism for this enhanced performance and provides an exciting route for improving the power factors of organic-inorganic hybrid thermoelectrics.

Coates, Nelson E.; Yee, Shannon K.; Russ, Boris; Urban, Jeffrey J.; Segalman, Rachel A.

2012-02-01

30

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

31

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; Lind, Johan Ulrik

32

Interpenetrating networks of two conducting polymers  

DEFF Research Database (Denmark)

Interpenetrating networks (IPNs) of two conjugated polymers are prepared by a combination of a chemical oxidation step and a vapour phase polymerisation step on non-conducting surfaces. In this work ferric tosylate was used as the oxidant as it gives very smooth and homogeneous coatings, and because its reaction products can be removed efficiently after the formation of the composite. Several combinations of polymers are demonstrated, and the versatility of the proposed method allows extensions to a wide range of conjugated polymers. The IPNs show optical and electrochemical characteristics, which are sums of the characteristics from the participating conducting polymers.

Winther-Jensen, BjØrn; West, Keld

2005-01-01

33

“Electro-Click” on Conducting Polymer Films  

DEFF Research Database (Denmark)

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

Hansen, Thomas Steen; Lind, Johan Ulrik

34

Conductivity studies on solid polymer electrolytes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 features, applicability, and validity of DC and AC conductivity measurements. Techniques for the identification of the individual species responsible for conduction are then briefly reviewed.

Sequeira, C.; Plancha, M.; Arau?jo, L.

1994-01-01

35

Electronically conducting polymers with silver grains  

Science.gov (United States)

The present invention provides electronically conducting polymer films formed from photosensitive formulations of pyrrole and an electron acceptor that have been selectively exposed to UV light, laser light, or electron beams. The formulations may include photoinitiators, flexibilizers, solvents and the like. These solutions can be used in applications including printed circuit boards and through-hole plating and enable direct metallization processes on non-conducting substrates. After forming the conductive polymer patterns, a printed wiring board can be formed by sensitizing the polymer with palladium and electrolytically depositing copper.

Murphy, Oliver J. (Inventor); Hitchens, G. Duncan (Inventor); Hodko, Dolibor (Inventor)

1999-01-01

36

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

37

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

38

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

39

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

Science.gov (United States)

PVP (poly(vinyl pyrrolidone)) is a common polymer that behaves as a surface-regulating agent that shapes metal nanocrystals in the polyol process. We have used different polymers containing tertiary amide groups, namely PVCL (poly(vinyl caprolactam)) and PDMAm (poly(N,N-dimethyl acrylamide)), for the synthesis of gold polyhedrons, including octahedrons, cuboctahedrons, cubes, and higher polygons, under the present polyol reaction conditions. The basicity and surface coordination power of the polymers are in the order of PVCL, PVP, and PDMAm. A correlation is observed between the coordination power of the polymers and the resulting gold nanocrystal size. Strong coordination and electron donation from the polymer functional groups to the gold surface restrict particle growth rates, which leads to small nanocrystals. The use of PVCL can yield gold polyhedral structures with small sizes, which cannot be achieved in the reactions with PVP. Simultaneous hydrolysis of the amide group in PDMAm leads to carboxylate functionality, which is very useful for generating chemical and bioconjugates through the formation of ester and amide bonds. PMID:21656861

Lee, Seon Joo; Park, Garam; Seo, Daeha; Ka, Duyoun; Kim, Sang Youl; Chung, Im Sik; Song, Hyunjoon

2011-07-18

40

Direct synthesis of PbS nanocrystals capped with 4-fluorothiophenol in semiconducting polymer  

Energy Technology Data Exchange (ETDEWEB)

We report on a simple chemical route to directly synthesize PbS nanocrystals capped with 4-fluorothiophenol in poly[2-methoxy-5-(3{sup '},7{sup '}-dimethyloctyloxy)-1,4-phenylenevinylene] semiconducting polymer. An intermediate composite, which has been characterized by X-ray photoelectron spectroscopy, has been synthesized to be used as nanocrystal precursor that contains both the metal and capping agent. Transmission electron microscopy images show that good quality nanoparticles with a mean size of {approx}5 nm are obtained with this method. Optical absorption measurements show that the absorption band of the polymer is extended as the PbS nanoparticles are included. Photoluminescence of the polymer becomes partially quenched as the concentration of the nanoparticles is increased in the composite.

Ferrer, J.C., E-mail: jc.ferrer@umh.es [Area de Electronica, Universidad Miguel Hernandez, Av. Universidad s/n, Ed. Torrepinet, 03202 Elche (Spain); Salinas-Castillo, A. [IBMC, Universidad Miguel Hernandez, Av. Universidad s/n, Ed. Torregaitan, 03202 Elche (Spain); Alonso, J.L.; Fernandez de Avila, S. [Area de Electronica, Universidad Miguel Hernandez, Av. Universidad s/n, Ed. Torrepinet, 03202 Elche (Spain); Mallavia, R. [IBMC, Universidad Miguel Hernandez, Av. Universidad s/n, Ed. Torregaitan, 03202 Elche (Spain)

2010-08-01

 
 
 
 
41

Direct synthesis of PbS nanocrystals capped with 4-fluorothiophenol in semiconducting polymer  

International Nuclear Information System (INIS)

We report on a simple chemical route to directly synthesize PbS nanocrystals capped with 4-fluorothiophenol in poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene] semiconducting polymer. An intermediate composite, which has been characterized by X-ray photoelectron spectroscopy, has been synthesized to be used as nanocrystal precursor that contains both the metal and capping agent. Transmission electron microscopy images show that good quality nanoparticles with a mean size of ?5 nm are obtained with this method. Optical absorption measurements show that the absorption band of the polymer is extended as the PbS nanoparticles are included. Photoluminescence of the polymer becomes partially quenched as the concentration of the nanoparticles is increased in the composite.

42

Conducting Polymers in Neural Stimulation Applications  

Science.gov (United States)

With advances in neural prostheses, the demand for high-resolution and site-specific stimulation is driving microelectrode research to develop electrodes that are much smaller in area and longer in lifetime. For such arrays, the choice of electrode material has become increasingly important. Currently, most neural stimulation devices use platinum, iridium oxide, or titanium nitride electrodes. Although those metal electrodes have low electrode impedance, high charge injection capability, and high corrosion resistance, the neural interface between solid metal and soft tissue has undesilable characteristics. Recently, several conducting polymers, also known as inherently conducting polymers (ICPs), have been explored as new electrode materials for neural interfaces. Polypyrrole (PPy), polyaniline (PANi), and poly(3,4-ethylenedioxythiophene) (PEDOT) polymers may offer the organic, improved bionic interface that is necessary to promote biocompatibility in neural stimulation applications. While conducting polymers hold much promise in biomedical applications, more research is needed to further understand the properties of these materials. Factors such as electrode impedance, polymer volume changes under electrical stimulation, charge injection capability, biocompatibility, and long-term stability are of significant importance and may pose as challenges in the future success of conducting polymers in biomedical applications.

Zhou, David D.; Cui, X. Tracy; Hines, Amy; Greenberg, Robert J.

43

Thermal conductivity and multiferroics of electroactive polymers and polymer composites  

Science.gov (United States)

Electronically conducting polymers and electromechanical polymers are the two important branches of the cutting-edge electroactive polymers. They have shown significant impact on many modern technologies such as flat panel display, energy transport, energy conversion, sensors and actuators. To utilize conducting polymers in microelectronics, optoelectronics and thermoelectrics, it is necessary to have a comprehensive study of their thermal conductivity since thermal conductivity is a fundamental materials property that is particularly important and sometimes a determining factor of the device performance. For electromechanical polymers, larger piezoelectric effect will contribute to the improvement of magnetoelectric (ME) coupling efficiency in their multiferroic composites. This dissertation is devoted to characterizing electronically conducting polymers for their electrical and thermal conductivity, and developing new classes of electromechanical polymers and strain-mediated electromechanical polymer-based multiferroic ME composites. Conducting polymers opened up new possibilities for devices combining novel electrical and thermal properties, but there has been limited understanding of the length-scale effect of the electrical and thermal conductivity, and the mechanism underlying the electricity and heat transport behavior. In this dissertation, the analytical model and experimental technique are presented to measure the in-plane thermal conductivity of polyaniline thin films. For camphorsulfonic acid doped polyaniline patterned on silicon oxide/silicon substrate using photolithography and reactive ion etching, the thermal conductivity of the film with thickness of 20 nm is measured to be 0.0406 W/m?K, which significantly deviates from their bulk (> 0.26 W/m?K). The size effect on thermal conductivity at this scale is attributed to the significant phonon boundary scattering. When the film goes up to 130 nm thick, the thermal conductivity increases to 0.166 W/m?K, greatly affected by the phonon-phonon scattering and phonon boundary scattering. When the films are thicker than 130 nm, heat capacity also plays an important role in thermal conduction in polyaniline. The same technique is extended to measure the electrical and thermal conductivity of 55 nm thick polyaniline thin films doped with different levels of camphorsulfonic acid. Results indicate that the effect of the doping level (camphorsulfonic acid/polyaniline ratio) is more pronounced on electrical conductivity than on thermal conductivity, thereby greatly affecting their ratio that determines the thermoelectric efficiency. At the 60% doping level, polyaniline thin film exhibits the maximum electrical and thermal conductivity due to the formation of mostly delocalized polaron structures. It is suggested that polarons are the charge carriers responsible for the electrical conduction, while phonons play a dominant role in the heat conduction in doped polyaniline thin films. Multiferroic materials combine unusual elastic, magnetic and electric properties, and have promising applications in many areas, such as sensors, transducers and read/write memory devices. For strain-mediated multiferroic ME composites, their ME effect are generated as a product property of the piezoelectric phase and magnetostrictive phase. In this dissertation, new multiferroic composites are developed and presented. One of them is based on chain-end cross-linked ferroelectric poly(vinylidene fluoride-co-trifluoroethylene) (PVDF-TrFE). With a low dc bias magnetic field, the ME coefficient of this composite is 17.7 V/cm Oe at non-resonance and 383 V/cm Oe at resonance, well above the reported ME voltage coefficient of polymer based ME composite in current literature. ME composite based on poly(vinylidene fluoride-co-hexafluoropropylene) P(VDF-HFP) are also developed in this dissertation. Crystalline beta phase structure in P(VDF-HFP) is produced by uniaxially stretching of pre-melted and quenched films. ME voltage coefficient as a function of dc magnetic field at different poling field

Jin, Jiezhu

44

Phonon dispersion and thermal conductivity of nanocrystal superlattices using three-dimensional atomistic models  

Energy Technology Data Exchange (ETDEWEB)

A computational study of thermal conductivity and phonon dispersion of gold nanocrystal superlattices is presented. Phonon dispersion curves, reported here for the first time from combined molecular dynamics and lattice dynamics calculations, show multiple phononic band gaps and consist of many more dispersion branches than simple atomic crystals. Fully atomistic three dimensional molecular dynamics calculations of thermal conductivity using the Green Kubo method are also performed for the first time on these materials. Thermal conductivity is observed to increase for increasing nanocrystal core size and decrease for increasing surface ligand density. Our calculations predict values in the range 0.1–1?W/m K that are consistent with reported experimental results.

Zanjani, Mehdi B.; Lukes, Jennifer R., E-mail: jrlukes@seas.upenn.edu [Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States)

2014-04-14

45

Phonon dispersion and thermal conductivity of nanocrystal superlattices using three-dimensional atomistic models  

International Nuclear Information System (INIS)

A computational study of thermal conductivity and phonon dispersion of gold nanocrystal superlattices is presented. Phonon dispersion curves, reported here for the first time from combined molecular dynamics and lattice dynamics calculations, show multiple phononic band gaps and consist of many more dispersion branches than simple atomic crystals. Fully atomistic three dimensional molecular dynamics calculations of thermal conductivity using the Green Kubo method are also performed for the first time on these materials. Thermal conductivity is observed to increase for increasing nanocrystal core size and decrease for increasing surface ligand density. Our calculations predict values in the range 0.1–1?W/m K that are consistent with reported experimental results

46

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

47

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

48

Influence of nanoparticle shape on charge transport and recombination in polymer/nanocrystal solar cells.  

Science.gov (United States)

A key consideration for the efficient operation of hybrid solar cells based upon conjugated polymers and inorganic semiconductor nanocrystals is charge transport in the nanocrystal phase. Here we report the results of a study into the charge transport kinetics of polymer/nanocrystal solar cells based on blends poly(3-hexylthiophene) (P3HT) with either CdSe nano-dots or CdSe nano-tetrapods. Transient photocurrent measurements reveal significant differences in the charge transport kinetics of nano-dot and nano-tetrapod hybrid cells, with the charge collection of the P3HT/CdSe nano-dot device severely limited by charge trapping. In comparison the nano-tetrapod cell exhibits significantly reduced charge trapping compared to the nano-dot cell accounting for the improved fill-factor and overall device efficiency. Transient photovoltage measurements have also been employed that demonstrate slower recombination rates in the P3HT/CdSe tetrapod device compared to the P3HT/CdSe dot device. These observations directly identify nanoparticle shape as a critical factor influencing the charge transport and hence recombination in this benchmark hybrid system, confirming the hypothesis that the use of tetrapods improves device performance through an improvement in electron transport in the nanocrystal phase. PMID:24781139

Li, Zhe; Wang, Weiyuan; Greenham, Neil C; McNeill, Christopher R

2014-12-21

49

Ultrafast charge- and energy-transfer dynamics in conjugated polymer: cadmium selenide nanocrystal blends.  

Science.gov (United States)

Hybrid nanocrystal-polymer systems are promising candidates for photovoltaic applications, but the processes controlling charge generation are poorly understood. Here, we disentangle the energy- and charge-transfer processes occurring in a model system based on blends of cadmium selenide nanocrystals (CdSe-NC) with poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylene vinylene] (MDMO-PPV) using a combination of time-resolved absorption and luminescence measurements. The use of different capping ligands (n-butylamine, oleic acid) as well as thermal annealing allows tuning of the polymer-nanocrystal interaction. We demonstrate that energy transfer from MDMO-PPV to CdSe-NCs is the dominant exciton quenching mechanism in nonannealed blends and occurs on ultrafast time scales (<1 ps). Upon thermal annealing electron transfer becomes competitive with energy transfer, with a transfer rate of 800 fs independent of the choice of the ligand. Interestingly, we find hole transfer to be much less efficient than electron transfer and to extend over several nanoseconds. Our results emphasize the importance of tuning the organic-nanocrystal interaction to achieve efficient charge separation and highlight the unfavorable hole-transfer dynamics in these blends. PMID:24490650

Morgenstern, Frederik S F; Rao, Akshay; Böhm, Marcus L; Kist, René J P; Vaynzof, Yana; Greenham, Neil C

2014-02-25

50

Conducting polymer for high power ultracapacitor  

Science.gov (United States)

In accordance with the purposes of the present invention, as embodied and broadly described herein, the present invention is directed to an electrode having a conducting polymer active material for use in an ultracapacitor. The conducting polymer active material is electropolymerized onto a carbon paper substrate from a mixed solution of a dimer of (3,3' bithiophene) (BT) and a monomer that is selected from the group of thiophenes derived in the 3-position, having an aryl group attached to thiophene in the 3-position or having aryl and alkly groups independently attached to thiophene in the 3 and 4 positions.

Shi, Steven Z. (Latham, NY); Gottesfeld, Shimshon (Los Alamos, NM)

2002-01-01

51

Orienting semi-conducting ?-conjugated polymers.  

Science.gov (United States)

The present review focuses on the recent progress made in thin film orientation of semi-conducting polymers with particular emphasis on methods using epitaxy and shear forces. The main results reported in this review deal with regioregular poly(3-alkylthiophene)s and poly(dialkylfluorenes). Correlations existing between processing conditions, macromolecular parameters and the resulting structures formed in thin films are underlined. It is shown that epitaxial orientation of semi-conducting polymers can generate a large palette of semi-crystalline and nanostructured morphologies by a subtle choice of the orienting substrates and growth conditions. PMID:24302347

Brinkmann, Martin; Hartmann, Lucia; Biniek, Laure; Tremel, Kim; Kayunkid, Navaphun

2014-01-01

52

Universal frequency-dependent ac conductivity of conducting polymer networks  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A model based on the aspect of the distribution of the length of conduction paths accessible for electric charge flow reproduces the universal power-law dispersive ac conductivity observed in polymer networks and, generally, in disordered matter. Power exponents larger than unity observed in some cases are physically acceptable within this model. A saturation high frequency region is also predicted, in agreement with experimental results. There does not exist a universal fra...

Papathanassiou, A. N.; Sakellis, I.; Grammatikakis, J.

2008-01-01

53

Impregnation of porous silicon with conducting polymers  

Energy Technology Data Exchange (ETDEWEB)

Fabrication of porous silicon layers using the electrochemical technique followed by filling the nanopores with a group of conducting polymers is investigated. Our findings revealed that the deposition of polymer proceeds homogeneously inside the nanopores strating from the pore bottom and propagates into the outer surface. The polymerization process was conducted and controlled by the potentiostatic and galvanostatic modes with characteristic, defined polymerization stages. As-formed hybrid nanocomposites were characterized using different analytical techniques. Polypyrrole, polyaniline and polythiophene were tested in this study. By selective dissolution of porous silicon template, polymeric nanowires were obtained. The fabrication process, the electrochemical measurements and the porous silicon filling mechanism with polymer are thoroughly addressed and discussed (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Harraz, Farid A. [Advanced Materials Technology Department, Central Metallurgical Research and Development Institute (CMRDI), PO Box: 87, Hewan, 11421 Cairo (Egypt)

2011-06-15

54

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

55

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

56

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

57

Ion-Conducting Organic/Inorganic Polymers  

Science.gov (United States)

Ion-conducting polymers that are hybrids of organic and inorganic moieties and that are suitable for forming into solid-electrolyte membranes have been invented in an effort to improve upon the polymeric materials that have been used previously for such membranes. Examples of the prior materials include perfluorosulfonic acid-based formulations, polybenzimidazoles, sulfonated polyetherketone, sulfonated naphthalenic polyimides, and polyethylene oxide (PEO)-based formulations. Relative to the prior materials, the polymers of the present invention offer greater dimensional stability, greater ease of formation into mechanically resilient films, and acceptably high ionic conductivities over wider temperature ranges. Devices in which films made of these ion-conducting organic/inorganic polymers could be used include fuel cells, lithium batteries, chemical sensors, electrochemical capacitors, electrochromic windows and display devices, and analog memory devices. The synthesis of a polymer of this type (see Figure 1) starts with a reaction between an epoxide-functionalized alkoxysilane and a diamine. The product of this reaction is polymerized by hydrolysis and condensation of the alkoxysilane group, producing a molecular network that contains both organic and inorganic (silica) links. The silica in the network contributes to the ionic conductivity and to the desired thermal and mechanical properties. Examples of other diamines that have been used in the reaction sequence of Figure 1 are shown in Figure 2. One can use any of these diamines or any combination of them in proportions chosen to impart desired properties to the finished product. Alternatively or in addition, one could similarly vary the functionality of the alkoxysilane to obtain desired properties. The variety of available alkoxysilanes and diamines thus affords flexibility to optimize the organic/inorganic polymer for a given application.

Kinder, James D.; Meador, Mary Ann B.

2007-01-01

58

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

59

Electrical Noise in Individual Conducting Polymer Nanowires  

Science.gov (United States)

Electrical property characterizations of conducting polymer nanostructures have been limited primarily to resistance measurements. Electrical noise is one aspect that is usually overlooked, yet critical to their device performance. Moreover, electrical noise is more sensitive to the polymer doping and microstructure than resistance, which makes it particularly interesting for sensor applications. In this talk, we will present the results on the electrical noise measurements of individual multisegmented electrodeposited nanowires based on Poly(3,4-ethylenedioxythiophene (PEDOT) [1]. The polymer was electrochemically doped with either poly(4-styrenesulfonic acid) (PSS) or perchlorate (ClO4). The nanowires had gold contacts on both ends and were measured in four-point and two-point configurations. We found that the electrical noise behavior is typical of 1/f noise, with a spectral density that depends on the polymer structure and is affected by the ambient conditions. Our data show that the contact noise represents a significant contribution to the total noise level. We will discuss the interpretation of these results assuming that the polymer is a disordered conductor. [1] Cao et al., Nano Letters Article ASAP

Kovalev, Alexey; Cao, Yanyan; Mayer, Theresa; Mallouk, Thomas

2009-03-01

60

Soliton and polaron dynamics in conducting polymers  

International Nuclear Information System (INIS)

Solitons and polarons in conducting polymers are strongly coupled electron-lattice excitations. The lattice relaxation theory generalized by us to include the self-consistency of multi-electron states with lattice symmetry-breaking is summarized. The discrete symmetries and corresponding selection rules for both radiative and nonradiative processes are discussed. Theoretically calculated probability of nonradiative decay of an electron-hole pair into a soliton pair and that of electron (hole) into polaron as well as the probability of soliton pair photo-generation is compared with results of numerical and laboratory experiments. The resonance Raman scattering data of cis-polyacetylene are interpreted in terms of a bipolaron model. The parameters involved are determined directly from experimental data. Other applications of lattice relaxation theory to conducting polymers are briefly mentioned. (author). 40 refs, 5 figs

 
 
 
 
61

Nanoscaled surface patterning of conducting polymers.  

Science.gov (United States)

In continuing the steady development of integrated-circuit-related fabrication, the ability to pattern conducting polymers into smaller and smaller sizes in order to realize devices with enhanced performance or even wholly new properties begins to take a more prominent role in their advanced applications. This review summarizes the recent advances in top-down and bottom-up patterning of conducting polymers on surfaces with different approaches including direct writing, in-situ synthesis or assembly, etching, and nanoscratching. All of the latest emerging strategies have the potential to go beyond the current state of the art towards real progress in terms of high-precision positioning, high resolution, high throughout, higher stability, facile processing, and lower-cost production. PMID:21506268

Jiang, Lin; Wang, Xing; Chi, Lifeng

2011-05-23

62

Gas Sensors Based on Conducting Polymers  

Directory of Open Access Journals (Sweden)

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

Gaoquan Shi

2007-03-01

63

Tandem and triple-junction polymer:nanocrystal hybrid solar cells consisting of identical subcells.  

Science.gov (United States)

Tandem and triple-junction polymer:nanocrystal hybrid solar cells with identical subcells based on P3HT:CdSe nanocrystal bulk heterojunctions (BHJs) are reported for the first time showing 2-fold and 3-fold increases of open-circuit voltage (VOC), respectively, relative to the single-junction cell. A combination of nanocrystalline ZnO and pH-neutral PEDOT:PSS is used as the interconnecting layer, and the thicknesses of subcells are optimized with the guidance of optical simulations. As a result, the average power conversion efficiency (PCE) exhibits a significant increase from 2.0% (VOC = 0.57 V) in single-junction devices to 2.7% (champion 3.1%, VOC = 1.28 V) in tandem devices and 2.3% (VOC = 1.98 V) in triple-junction devices. PMID:25233268

Lu, Haipeng; Bartynski, Andrew N; Greaney, Matthew J; Thompson, Mark E; Brutchey, Richard L

2014-10-22

64

Improving Polymer/Nanocrystal Hybrid Solar Cell Performance via Tuning Ligand Orientation at CdSe Quantum Dot Surface.  

Science.gov (United States)

Achieving superior solar cell performance based on the colloidal nanocrystals remains challenging due to their complex surface composition. Much attention has been devoted to the development of effective surface modification strategies to enhance electronic coupling between the nanocrystals to promote charge carrier transport. Herein, we aim to attach benzenedithiol ligands onto the surface of CdSe nanocrystals in the "face-on" geometry to minimize the nanocrystal-nanocrystal or polymer-nanocrystal distance. Furthermore, the "electroactive" ?-orbitals of the benzenedithiol are expected to further enhance the electronic coupling, which facilitates charge carrier dissociation and transport. The electron mobility of CdSe QD films was improved 20 times by tuning the ligand orientation, and high performance 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):CdSe nanocrystal hybrid solar cells were also achieved, showing a highest power conversion efficiency of 4.18%. This research could open up a new pathway to improve further the performance of colloidal nanocrystal based solar cells. PMID:25336155

Fu, Weifei; Wang, Ling; Zhang, Yanfang; Ma, Ruisong; Zuo, Lijian; Mai, Jiangquan; Lau, Tsz-Ki; Du, Shixuan; Lu, Xinhui; Shi, Minmin; Li, Hanying; Chen, Hongzheng

2014-11-12

65

Conducting polymer coated neural recording electrodes  

Science.gov (United States)

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

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

2013-02-01

66

Polymer-grafted cellulose nanocrystals as pH-responsive reversible flocculants.  

Science.gov (United States)

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

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

2013-09-01

67

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

68

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

69

Loosening quantum confinement: observation of real conductivity caused by hole polarons in semiconductor nanocrystals smaller than the Bohr radius.  

Science.gov (United States)

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 terahertz conductivity is purely imaginary. For nanocrystals with radii exceeding 5 nm, we observe the onset of real conductivity, which is attributed to the increasingly smaller separation between the hole states. Remarkably, this onset occurs for a nanocrystal radius significantly smaller than the bulk exciton Bohr radius a(B) ? 7 nm and cannot be explained by purely electronic transitions between hole states, as evidenced by tight-binding calculations. The real-valued conductivity observed in the larger nanocrystals can be explained by the emergence of mixed carrier-phonon, that is, polaron, states due to hole transitions that become resonant with, and couple strongly to, optical phonon modes for larger QDs. These polaron states possess larger oscillator strengths and broader absorption, and thereby give rise to enhanced real conductivity within the nanocrystals despite the confinement. PMID:22881597

Ulbricht, Ronald; Pijpers, Joep J H; Groeneveld, Esther; Koole, Rolf; Donega, Celso de Mello; Vanmaekelbergh, Daniel; Delerue, Christophe; Allan, Guy; Bonn, Mischa

2012-09-12

70

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

71

Conducting polymer films as model biological membranes  

International Nuclear Information System (INIS)

This paper shows the application of conducting polymers (CPs) for constructing model biological membranes in order to study potential formation mechanism. Two amino acids, asparagine and glutamine, were incorporated in the poly(pyrrole) matrix during electrochemical polymerization. The polymer film was characterized by infrared and X-ray photoelectron spectroscopy. The film morphology was studied by atomic force microscopy. The ion-exchange behavior of PPy-Asn and PPy-Gln membranes in dependence on the conditioning solution are characterized using an open circuit potentiometric measurements. Close-to-Nernstian sensitivity was observed for the films under equilibrium. During equilibration provoked by the change in concentration of magnesium and/or calcium ions, the differences in the shape and evolution of the potential response with time were observed. The varying potential-time behavior after a bulk concentration change has been explained by a different participation of the magnesium and calcium ions on the ground diffusion layer model (DLM)

72

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

73

Electrochemical relaxation at electrically conducting polymers  

Science.gov (United States)

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.; zarandi, M. B.

2008-08-01

74

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

75

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.

76

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...

Je?ro?me, Robert; Pagnoulle, Christophe; Detrembleur, Christophe; Thomassin, Jean-michel; Huynen, Isabelle; Bailly, Christian; Bednarz, Lucasz; Daussin, Raphae?l; Saib, Aimad

2006-01-01

77

Quantum dots: conjugated polymer/nanocrystal nanocomposites for renewable energy applications in photovoltaics and photocatalysis (small 22/2014).  

Science.gov (United States)

Nanocomposites comprising well-mixed semiconductor nanocrystals and conjugated polymers that have relative offset energy band structures can not only complement the light absorption range of the solar spectrum but also result in a dissociation of charge-transferred excitons upon absorption, with electrons transferring to the nanocrystals and holes remaining in the conjugated polymers. On page 4427, K.-H. Wei and co-workers find that this generates a photocurrent for photovoltaic applications or for reducing/oxidizing reactions for photocatalysis applications. PMID:25412456

Su, Yu-Wei; Lin, Wei-Hao; Hsu, Yung-Jung; Wei, Kung-Hwa

2014-11-01

78

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.

79

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 In(3+) into the ZnO lattice and consequent substitution of divalent Zn(2+) 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. PMID:24842309

Ghosh, Sirshendu; Saha, Manas; De, S K

2014-06-21

80

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 prience. Finally, the morphology of the printed pixels is influenced by the embedded nanofillers. (paper)

 
 
 
 
81

Chemical synthesis of chiral conducting polymers  

Science.gov (United States)

An process of forming a chiral conducting polymer, e.g., polyaniline, is provided including reacting a monomer, e.g., an aniline monomer, in the presence of a chiral dopant acid to produce a first reaction mixture by addition of a solution including a first portion of an oxidizing agent, the first portion of oxidizing agent characterized as insufficient to allow complete reaction of the monomer, and further reacting the first reaction mixture in the presence of the chiral dopant acid by addition of a solution including a second portion of the oxidizing agent, the second portion of oxidizing agent characterized as insufficient to allow complete reaction of the monomer, and repeating the reaction by addition of further portions of the oxidizing agent until the monomer reaction is complete to produce a chiral conducting polymer, e.g., polyaniline. A preferred process includes addition of a catalyst during the reaction, the catalyst selected from among the group consisting of phenylene diamine, aniline oligomers and amino-capped aniline oligomers and metal salts.The processes of the present invention further provide a resultant polyaniline product having a chirality level defined by a molar ellipticity of from about 40.times.10.sup.3 degree-cm.sup.2/decimole to about 700.times.10.sup.3 degree-cm.sup.2/decimole. The processes of the present invention further provide a resultant polyaniline product having a nanofiber structure with a diameter of from about 30 nanometers to about 120 nanometers and from about 1 micron to about 5 microns in length.

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

2009-01-13

82

Fast current limitation by conducting polymer composites  

Science.gov (United States)

The transition of materials from low resistivity to comparatively high resistivity can be utilized for current limitation, enabling permanent fuses that do not have to be replaced after an overload or short-circuit operation. An interesting class of materials for this purpose are particulate filled polymer composites with a strong positive temperature coefficient (PTC) of resistivity. If an applied current becomes too high, the PTC element is heated to its critical temperature and trips from the conducting into the insulating state. The dynamic heating of the composite upon current flow is described by a one-dimensional model. It is predicted that the heating of a composite depends on the size of the filler particles. Smaller filler particles should allow a faster heating and, hence, a better limitation of the current. Experimental verification is performed using composite of TiB2 particles in a polyethylene matrix. Commercial TiB2 powders with different particle-size distributions between 1 and 200 ?m were used. The specific resistivity of the composites is small, in the range of 0.01-0.02 ? cm. Around the melting temperature of the polymer, the resistivity increases within only 20 °C by seven orders of magnitude. In order to verify the expected dependence of the switching dynamic on the filler particle size, the tested elements had comparable electrical characteristics. Samples were prepared having, to a certain degree, the same specific resistivity, cross section, and total resistance. Free parameters were the length, and for some samples, the filler content. Short-circuit experiments show that for decreasing particle size the time until the material trips into the high-resistive state becomes shorter. The best current limitation occurs for composites containing particles in the range of 1-45 ?m. Current limitation starts already after 150 ?s, and a current density of up to 10 kA/cm2 can be switched off within a further 200 ?s. The experiments are in excellent agreement with the predictions from theory. Due to the low resistance in the cold state and the very fast limitation of electrical currents, PTC elements based on conducting polymers can be highly attractive for power applications.

Strümpler, R.; Maidorn, G.; Rhyner, J.

1997-05-01

83

Influence of Semiconductor Nanocrystal Concentration on Polymer Hole Transport in Hybrid Nanocomposites  

Directory of Open Access Journals (Sweden)

Full Text Available This article investigates hole transport in poly[2-methoxy-5-(2'-ethyl-hexyloxy-1,4-phenylene vinylene] (MEH-PPV/CdSe colloidal quantum dot (CQD nanocomposites using a modified time-of-flight photoconductivity technique. The measured hole drift mobilities are analyzed in the context of Bässler’s Gaussian disorder model and the correlated disorder model in order to determine the polymer internal morphology of hybrid nanocomposite thin films. This work shows that increasing the CdSe CQD concentration decreases the polymer hole mobility from ~5.9 × 10?6 cm2/Vs in an MEH-PPV film to ~8.1 × 10?8 cm2/Vs in a 20:80 (wt% MEH-PPV:CdSe CQD nanocomposite film (measured at 25 °C and ~2 × 105 V/cm. The corresponding disorder parameters indicate increasing disruption of interchain interaction with increasing CQD concentration. This work quantifies polymer chain morphology in hybrid nanocomposite thin films and provides useful information regarding the optimal use of semiconductor nanocrystals in conjugated polymer-based optoelectronics.

Ryan Pate

2012-01-01

84

Progress in using conductive polymers as corrosion-inhibiting coatings  

International Nuclear Information System (INIS)

A general review of the chemistry and corrosion control properties of electroactive polymers will be presented. These polymers are also known as conductive polymers (CPs), and this term will be used throughout this article. This paper will focus on both the synthesis of applicable CPs used for corrosion protection in various environments and their potential benefits over common organic barrier coatings

85

Proton Conducting Polymer Electrolyte Based on Pva-Pan  

Science.gov (United States)

Proton conducting polymer electrolytes based on blend polymer using Poly Vinyl Alcohol (PVA) and Poly Acrylo Nitrile (PAN) doped with ammonium nitrate have been prepared by solution casting method. The highest conductivity at room temperature (305K) has been found to be 1.8×10-3 S cm-1 for 15 mole % NH4NO3 doped PVA-PAN system. X ray Diffraction pattern of the doped and the undoped blend polymer electrolyte confirms the amorphous nature of blend polymer, when salt is added. The complex formation between the blend polymer and the salt has been confirmed by Fourier transform infrared spectroscopy.

Devi, S. Siva; Selvasekarapandian, S.; Rajeswari, N.; Genova, F. Kingslin Mary; Karthikeyan, S.; Raja, C. Sanjeevi

2013-07-01

86

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

87

Nobel Prize 2000: from conducting polymers to molecular electronics  

International Nuclear Information System (INIS)

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

88

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

89

High performance conducting polymer nanofiber biosensors for detection of biomolecules.  

Science.gov (United States)

Sensitive detection and selective determination of the physiologically important chemicals involved in brain function have drawn much attention for the diagnosis and treatment of brain diseases and neurological disorders. This paper reports a novel method for fabrication of enzyme entrapped-conducting polymer nanofibers that offer higher sensitivity and increased lifetime compared to glucose sensors that are based on conducting polymer films. PMID:24719293

Yang, Guang; Kampstra, Kelly L; Abidian, Mohammad Reza

2014-08-01

90

Spatially Selective Functionalization of Conducting Polymers by "Electroclick" Chemistry  

DEFF Research Database (Denmark)

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

Hansen, Thomas Steen; Daugaard, Anders Egede

2009-01-01

91

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

92

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)

93

Electromagnetic properties of conducting polymers encapsulated in an insulating matrix  

International Nuclear Information System (INIS)

The aim of this work is to study the electronic properties of conducting polymers encapsulated in zeolite. We studied two kinds of polymers: intrinsic conducting polymers (poly-pyrrole) and pyrolyzed polymers (polyacrylonitrile and poly-furfuryl alcohol). These systems were characterized by electron paramagnetic resonance and microwave conductivity measurements. In the first part, we present the preparation and the characterization of encapsulated poly-pyrrole. Conductivity measurements show that the encapsulated material is insulating, certainly because a strong interaction with the zeolite traps the charge carriers. In the second part, we focus on pyrolyzed encapsulated polyacrylonitrile. This system has a metal-like susceptibility at room temperature and a relatively high microwave conductivity. These results demonstrate the formation during the pyrolysis of extended aromatic clusters. Finally, we study pyrolyzed encapsulated poly-furfuryl alcohol. We show that the only effect of the pyrolysis is to fragment the polymers. We also discuss the spin relaxation and the EPR line broadening. (author)

94

Charging influence on current conduction in NiO thin film embedded with Ni nanocrystals  

International Nuclear Information System (INIS)

We have investigated the current conduction of NiO thin film embedded with Ni nanocrystals (nc-Ni) and the influence of charging in the nc-Ni/NiO thin film on the current transport. The hole trapping in the thin film under a negative charging voltage is found to greatly increase the current conduction measured at a positive voltage due to the enhancement of electric field at the interface between the thin film and Si substrate. Moreover, the current-voltage (I-V) characteristic follows a power-law relationship. In addition, the dc resistance of the thin film strongly depends on the magnitude of the charging voltage and charging time. These results could be used to realize a charging-controlled resistive memory effect.

95

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

96

Improved morphology in electrochemically grown conducting polymer films  

Energy Technology Data Exchange (ETDEWEB)

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

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

1990-12-31

97

Studies on conducting polymer and conducting polymerinorganic composite electrodes prepared via a new cathodic polymerization method  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A novel approach for the electrodeposition of conducting polymers and conducting polymer-inorganic composite materials is presented. The approach shows that conducting polymers, such as polypyrrole (PPy) and poly(3,4-ethylenedioxythiophene) (PEDOT) can be electrodeposited by the application of a cathodic bias that generates an oxidizing agent, NO+, via the in-situ reduction of nitrate anions. This new cathodic polymerization method allows for the deposition of PPy and PEDOT as three dimension...

Singh, Nikhilendra

2010-01-01

98

Patterning of conducting polymers using charged self-assembled monolayers.  

Science.gov (United States)

We introduce a new approach to pattern conducting polymers by combining oppositely charged conducting polymers on charged self-assembled monolayers (SAMs). The polymer resist pattern behaves as a physical barrier, preventing the formation of SAMs. The patterning processes were carried out using commercially available conducting polymers: a negatively charged PEDOT/PSS (poly(3,4-ethylene-dioxythiophene)/poly(4-stylenesulphonic acid)) and a positively charged polypyrrole (PPy). A bifunctional NH 2 (positively charged) or COOH (negatively charged) terminated alkane thiol or silane was directly self-assembled on a substrate (Au or SiO 2). A suspension of the conducting polymers (PEDOT/PSS and PPy) was then spin-coated on the top surface of the SAMs and allowed to adsorb on the oppositely charged SAMs via an electrostatic driving force. After lift-off of the polymer resist, i.e., poly(methyl methacrylate, PMMA), using acetone, the conducting polymers remained on the charged SAMs surface. Optical microscopy, Auger electron spectroscopy, and atomic force microscopy reveal that the prepared nanolines have low line edge roughness and high line width resolution. Thus, conducting polymer patterns with high resolution could be produced by simply employing charged bifunctional SAMs. It is anticipated that this versatile new method can be applied to device fabrication processes of various nano- and microelectronics. PMID:18661959

Jung, Mi-Hee; Lee, Hyoyoung

2008-09-01

99

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

100

Conductive polymer coatings for anodes in aqueous electrowinning  

Science.gov (United States)

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

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

2003-07-01

 
 
 
 
101

Characterization of metal nanoparticles/ conducting polymer prepared by radiation technique  

International Nuclear Information System (INIS)

Full text: Composites of conducting polymer-metal nanoparticles are of great interest in modern physical and chemical researchers due to their unique physical and chemical properties, which are distinct from those of the bulk metal and molecules .Conducting polymer-metal nanoparticles can be used in diverse fields such as electronics, electrocatalysts and optoelectronics. Conducting polymer and metal nanoparticles blended in polyvinyl alcohol (PVA) was synthesized by irradiating as films containing monomer and metal salt at different concentrations with gamma radiation technique. In the same time the conducting polymer and metal nanoparticles were formed due to oxidation of monomer and reduction of metal ion respectively by radiation. The structure analysis of conducting polymer-metal nanoparticles films were studied by X-Ray diffraction system which appears different diffraction peak angles respectively .The optical properties were investigated using UV -Vis spectrophotometer that show optical absorbance peak at ? = (780 , 430) nm of conducting polymer and metal nanoparticles respectively .From the UV-spectrum the band gap energy (Eg) was deduced and found to be decreases from (1.4, 2.8) eV at 10 kGy to (1.2,2.52) eV at 50 kGy for conducting polymer and metal nanoparticles respectively. (author)

102

Recent developments in polyurethane-based conducting polymer composites  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Polyurethane-based conducting composites with polyaniline, polythiophene or polypyrrole are in the class of modern macromolecular materials that combine the toughness and elasticity of polyurethane matrix with conductivity of intrinsically conducting polymers. Since the methods of preparation strongly influence the structure and properties of resulting composite/blend, this works aim at systematic description of polyurethane based conducting composites. This review has been ...

Njuguna, James A. K.; Pielichowski, Krzysztof

2004-01-01

103

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

104

FTIR AND IONIC CONDUCTIVITY STUDIES ON BLEND POLYMER ELECTROLYTES  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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), p...

Senthil, J.; Minimala, N. S.; GOVINDA NAGARAJAN; Mahendran, O.

2011-01-01

105

A Preliminary Study of Cyclic Voltammetry of a Conducting Polymer  

Science.gov (United States)

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

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

2007-05-01

106

High ion conducting polymer nanocomposite electrolytes using hybrid nanofillers.  

Science.gov (United States)

There is a growing shift from liquid electrolytes toward solid polymer electrolytes, in energy storage devices, due to the many advantages of the latter such as enhanced safety, flexibility, and manufacturability. The main issue with polymer electrolytes is their lower ionic conductivity compared to that of liquid electrolytes. Nanoscale fillers such as silica and alumina nanoparticles are known to enhance the ionic conductivity of polymer electrolytes. Although carbon nanotubes have been used as fillers for polymers in various applications, they have not yet been used in polymer electrolytes as they are conductive and can pose the risk of electrical shorting. In this study, we show that nanotubes can be packaged within insulating clay layers to form effective 3D nanofillers. We show that such hybrid nanofillers increase the lithium ion conductivity of PEO electrolyte by almost 2 orders of magnitude. Furthermore, significant improvement in mechanical properties were observed where only 5 wt % addition of the filler led to 160% increase in the tensile strength of the polymer. This new approach of embedding conducting-insulating hybrid nanofillers could lead to the development of a new generation of polymer nanocomposite electrolytes with high ion conductivity and improved mechanical properties. PMID:22369495

Tang, Changyu; Hackenberg, Ken; Fu, Qiang; Ajayan, Pulickel M; Ardebili, Haleh

2012-03-14

107

Anisotropic Thermal Conduction in Polymers and its Molecular Origins  

Science.gov (United States)

The strong coupling of mechanical and thermal effects in polymer flows have a significant impact on both the processing and final properties of the material. Simple molecular arguments suggest that Fourier's law must be generalized to allow for anisotropic thermal conductivity in polymers subjected to deformation. In our laboratory we have developed a novel application of the optical technique known as Forced Rayleigh Scattering to obtain quantitative measurements of components of the thermal diffusivity (conductivity) tensor in polymers subjected to deformations. We report measurements of anisotropic thermal diffusivity and stress in molten, cross-linked and solid polymers subjected to several types of flows. The deformed samples have significant anisotropy in polymer chain orientation that results in significant anisotropy in thermal conductivity. Stress and thermal conductivity data support the validity of the stress-thermal rule, which is analogous to the well-known stress-optic rule. We also report measurements on solid polymers with isotropic polymer chain orientation that are under stress, which display rather unexpected behavior. These measurements are used to develop an understanding of the molecular origins of anisotropic thermal conduction in polymeric material

Schieber, Jay; Venerus, David; Gupta, Sahil

2013-03-01

108

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

109

Synthesis and investigation of new electronically and ionically conducting polymers  

Energy Technology Data Exchange (ETDEWEB)

The electronically and ionically conducting ion exchange polymers, protonated poly-[3-(pyrrol-1-ylmethyl)pyridine] (poly-HPMP[sup +]), poly-[1-methyl-3-(pyrrol-1-ylmethyl)pyridinium tetrafluoroborate] (poly-MPMP[sup +] BF[sub 4][sup [minus

Mao, H.

1991-01-01

110

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

111

Thermal conductivity in nanostructured films: from single cellulose nanocrystals to bulk films.  

Science.gov (United States)

We achieved a multiscale description of the thermal conductivity of cellulose nanocrystals (CNCs) from single CNCs (?0.72-5.7 W m(-1) K(-1)) to their organized nanostructured films (?0.22-0.53 W m(-1) K(-1)) using experimental evidence and molecular dynamics (MD) simulation. The ratio of the approximate phonon mean free path (?1.7-5.3 nm) to the lateral dimension of a single CNC (?5-20 nm) suggested a contribution of crystal-crystal interfaces to polydisperse CNC film's heat transport. Based on this, we modeled the thermal conductivity of CNC films using MD-predicted single crystal and interface properties along with the degree of CNC alignment in the bulk films using Hermans order parameter. Film thermal conductivities were strongly correlated to the degree of CNC alignment and the direction of heat flow relative to the CNC chain axis. The low interfacial barrier to heat transport found for CNCs (?9.4 to 12.6 m(2) K GW(-1)), and their versatile alignment capabilities offer unique opportunities in thermal conductivity control. PMID:25286405

Diaz, Jairo A; Ye, Zhijiang; Wu, Xiawa; Moore, Arden L; Moon, Robert J; Martini, Ashlie; Boday, Dylan J; Youngblood, Jeffrey P

2014-11-10

112

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

113

Recent developments in intrinsically conductive polymer coatings for corrosion protection  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Intrinsically conductive polymers have achieved demanding interest in the field of corrosion control coatings owing to their conductive ability and also due to the strict environmental regulations on conventional heavy metals coatings. This multipurpose class of polymers has shown to be effective and proven themselves as a potential alternate for these hazardous heavy metal coatings in order to control the corrosion properties of metals or alloys. The basic purpose of this paper is only to hi...

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

2010-01-01

114

Characterisation of Proton Conducting Polymer Electrolyte Based on Pan  

Science.gov (United States)

The polymer electrolytes composed of polyacrylonitrile (PAN) with various concentration of ammonium nitrare (NH4NO3) salt have been prepared by solution casting method, using DMF as solvent. The increase in amorphous nature of the polymer electrolytes has been confirmed by Xray diffraction analysis. The complex formation between polymer and dissociated salt has been confirmed by Fourier transform infrared spectroscopy. From the Ac impedance spectroscopic analysis, the ionic conductivity of 20 mol% NH4NO3 doped polymer complex has been found to be 2.742 × 10-6 S cm-1 at room temperature. The conductivity has been increased when the temperature is increased. The activation energy of 20 mol% NH4NO3 doped polymer electrolyte was calculated using Arrhenius plot and it has been found to be 0.58 eV. The dielectric permitivitty (?*) and electric modulus (m*) have been discussed.

Nithya, S.; Selvasekarapandian, S.; Rajeswari, N.; Sikkanthar, S.; Karthikeyan, S.; Sanjeeviraja, C.

2013-07-01

115

Cationic polymer brush-modified cellulose nanocrystals for high-affinity virus binding  

Science.gov (United States)

Surfaces capable of high-affinity binding of biomolecules are required in several biotechnological applications, such as purification, transfection, and sensing. Therein, the rod-shaped, colloidal cellulose nanocrystals (CNCs) are appealing due to their large surface area available for functionalization. In order to exploit electrostatic binding, their intrinsically anionic surfaces have to be cationized as biological supramolecules are predominantly anionic. Here we present a facile way to prepare cationic CNCs by surface-initiated atom-transfer radical polymerization of poly(N,N-dimethylaminoethyl methacrylate) and subsequent quaternization of the polymer pendant amino groups. The cationic polymer brush-modified CNCs maintained excellent dispersibility and colloidal stability in water and showed a ?-potential of +38 mV. Dynamic light scattering and electron microscopy showed that the modified CNCs electrostatically bind cowpea chlorotic mottle virus and norovirus-like particles with high affinity. Addition of only a few weight percent of the modified CNCs in water dispersions sufficed to fully bind the virus capsids to form micrometer-sized assemblies. This enabled the concentration and extraction of the virus particles from solution by low-speed centrifugation. These results show the feasibility of the modified CNCs in virus binding and concentrating, and pave the way for their use as transduction enhancers for viral delivery applications.Surfaces capable of high-affinity binding of biomolecules are required in several biotechnological applications, such as purification, transfection, and sensing. Therein, the rod-shaped, colloidal cellulose nanocrystals (CNCs) are appealing due to their large surface area available for functionalization. In order to exploit electrostatic binding, their intrinsically anionic surfaces have to be cationized as biological supramolecules are predominantly anionic. Here we present a facile way to prepare cationic CNCs by surface-initiated atom-transfer radical polymerization of poly(N,N-dimethylaminoethyl methacrylate) and subsequent quaternization of the polymer pendant amino groups. The cationic polymer brush-modified CNCs maintained excellent dispersibility and colloidal stability in water and showed a ?-potential of +38 mV. Dynamic light scattering and electron microscopy showed that the modified CNCs electrostatically bind cowpea chlorotic mottle virus and norovirus-like particles with high affinity. Addition of only a few weight percent of the modified CNCs in water dispersions sufficed to fully bind the virus capsids to form micrometer-sized assemblies. This enabled the concentration and extraction of the virus particles from solution by low-speed centrifugation. These results show the feasibility of the modified CNCs in virus binding and concentrating, and pave the way for their use as transduction enhancers for viral delivery applications. Electronic supplementary information (ESI) available: CNC surface chain fraction and degree of substitution after BriBBr modification, NMR spectra of the SI-ATRP reaction mixture at 0 and 120 min, conversion of the DMAEMA monomer during SI-ATRP, DLS size distribution profiles of CNCs and CNC-g-P(QDMAEMA), TEM images of NoV-VLPs and their complexes with CNC-g-P(QDMAEMA) at 0 mM NaCl. See DOI: 10.1039/c4nr03584d

Rosilo, Henna; McKee, Jason R.; Kontturi, Eero; Koho, Tiia; Hytönen, Vesa P.; Ikkala, Olli; Kostiainen, Mauri A.

2014-09-01

116

A conducting coordination polymer based on assembled Cu9 cages.  

Science.gov (United States)

We report on a novel highly semiconducting 1D coordination polymer architecture obtained by the reaction of a Cu(II) salt with 2,2'-dipyridyldisulfide under microwave solvothermal conditions. This reaction proceeds with an unusual C-S and S-S bond cleavage of the 2,2'-dipyridyldisulfide ligand. The unprecedented architecture of this coordination polymer consists of a 1D chain formed by the assembling of Cu9 cluster cages. The electrical conductivity behavior of this novel material suggests new perspectives for the use of coordination polymers as electrical conducting materials. PMID:18817369

Delgado, Salomé; Sanz Miguel, Pablo J; Priego, José L; Jiménez-Aparicio, Reyes; Gómez-García, Carlos J; Zamora, Félix

2008-10-20

117

Interfacial ionic and electronic conductivity in polymers  

Energy Technology Data Exchange (ETDEWEB)

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

Shriver, D.F.

1989-06-01

118

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

119

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.

120

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

 
 
 
 
121

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

122

Method of forming electronically conducting polymers on conducting and nonconducting substrates  

Science.gov (United States)

The present invention provides electronically conducting polymer films formed from photosensitive formulations of pyrrole and an electron acceptor that have been selectively exposed to UV light, laser light, or electron beams. The formulations may include photoinitiators, flexibilizers, solvents and the like. These solutions can be used in applications including printed circuit boards and through-hole plating and enable direct metallization processes on non-conducting substrates. After forming the conductive polymer patterns, a printed wiring board can be formed by sensitizing the polymer with palladium and electrolytically depositing copper.

Murphy, Oliver J. (Inventor); Hitchens, G. Duncan (Inventor); Hodko, Dalibor (Inventor); Clarke, Eric T. (Inventor); Miller, David L. (Inventor); Parker, Donald L. (Inventor)

2001-01-01

123

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

124

Features of radiation electric conductivity of some polar polymers  

International Nuclear Information System (INIS)

Conductivity of certain polar polymers excited by low energy electrons (65 keV) at the effect duration from 5 ?s to 1 ms in vacuum is studied. Specific electric conductivity of the polymers studied which has been presented proved to be considerably lower the non-polar polytetrafluoroethylene and slightly polar polystyrene and polyethyleneterephthalate. In electric fields E0 5 V/cm Ohm law is obeyed for PMMA and polycarbonate but not for cellulose triacetate. Possible role of free charges in the induced electric conductivity is discussed

125

Electrochemical sensors based on conducting polymer-polypyrrole  

International Nuclear Information System (INIS)

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

126

Delocalization in I sub 2 -doped PBMPV conducting polymers  

CERN Document Server

Nuclear magnetic resonance and conductivity measurements were made for a series of I sub 2 -doped poly[2-buthoxy-5-methoxy-1,4-phenylenevinylene] (PBMPV) conducting polymers. Study of the spin dynamics in these unique systems enabled us to present comprehensive evidence for delocalization of the charge-carrier wavefunction as the doping proceeds.

Lee, C H; Jin, J I

1999-01-01

127

Conductivity percolation in polyiodide/polymer complexes  

Energy Technology Data Exchange (ETDEWEB)

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

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

1993-08-01

128

Intriguing Heat Conduction of a Polymer Chain  

CERN Document Server

We study heat conduction in a one-dimensional chain of particles with longitudinal as well as transverse motions. The particles are connected by two-dimensional harmonic springs together with bending angle interactions. Using equilibrium and nonequilibrium molecular dynamics, three types of thermal conducting behaviors are found: a logarithmic divergence with system sizes for large transverse coupling, 1/3 power-law at intermediate coupling, and 2/5 power-law at low temperatures and weak coupling. The results are consistent with a simple mode-coupling analysis of the same model. The 1/3 power-law divergence should be a generic feature for models with transverse motions.

Wang, J S; Wang, Jian-Sheng; Li, Baowen

2004-01-01

129

Ionic motion in PEDOT and PPy conducting polymer bilayers  

DEFF Research Database (Denmark)

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

Skaarup, Steen

2006-01-01

130

Hexavalent chromium removal mechanism using conducting polymers.  

Science.gov (United States)

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

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

2013-05-15

131

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

132

Electronic structure calculations on helical conducting polymers.  

Science.gov (United States)

We present a study of the electronic structure and derived properties of polyfurane (PFu), polypyrrol (PPy), and polythiophene (PTh). Two spatial arrangements are considered: trans chain (tc-PFu, tc-PPy, tc-PTh) and cis ?-helical (?-PFu, ?-PPy, ?-PTh). Even at the small sizes considered here, helical conformations appear to be stable. Band gaps of pure, undoped oligomers fall into the semiconductor range. Density of states (DOS) analysis suggest dense valence and conduction bands. Bond length alternation analysis predicts almost complete delocalization of the ? clouds in all spatial arrangements. Doping with electron donors or electron-withdrawing impurities reduces all band gaps close to the metallic regime in addition to increasing the DOS for the valence and conduction bands. PMID:20873834

Ripoll, Juan D; Serna, Andrei; Guerra, Doris; Restrepo, Albeiro

2010-10-21

133

Recent developments in intrinsically conductive polymer coatings for corrosion protection  

Directory of Open Access Journals (Sweden)

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

M. Z. Iqbal

2010-12-01

134

Ion-Conducting Polymer Films as Chemical Sensors  

International Nuclear Information System (INIS)

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

135

Conducting polymers as active materials in electrochemical capacitors  

Science.gov (United States)

Electronically conducting polymer represent an interesting clas of materials for use in electrochemical capacitors thanks to the combination of high capacitive energy density and low materials cost. Three generalized typed of electrochemical capacitors can be constructed using conducting polymers as active material, and in the third of these, which utilized conducting polymers that can be both n- and p-doped, energy densities of up to 39 Wh per kg of active material on both electrodes have been demonstrated. This energy density is obtained using poly-3-(4-fluorophenyl)-thiophene (PEPT) in an electrolyte of 1 M tetramethylammonium trifluoromethanesulfonate (TMATFMS) in acetonitrile. This unique system exhibits reversible n- and p-doping to high charge density in relatively thich films of the active polymer and a cell voltage exceeding 3 V in the fully charged state. Impedance data for both n- and p-doped PFPT suggest that high power densities can be obtained in electrochemical capacitors based on this active conducting polymer.

Rudge, Andy; Davey, John; Raistrick, Ian; Gottesfeld, Shimshon; Ferraris, John P.

136

Thin film conductive polymer for microactuator and micromuscle applications  

Energy Technology Data Exchange (ETDEWEB)

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

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

1994-04-14

137

Mechanism of actuation in conducting polymers: Osmotic expansion  

DEFF Research Database (Denmark)

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

Bay, Lasse; Jacobsen, Torben

2001-01-01

138

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)

139

Fabrication, Modelling and Application of Conductive Polymer Composites  

Science.gov (United States)

Electroactive polymers (EAP) are an emerging branch of smart materials that possess the capability to change shape in the presence of an electric field. Opportunities for the advancement of knowledge were identified in the branch of EAP consisting of inherently electrically conductive polymers. This dissertation explores methods by which the unique properties of composite materials having conductive polymers as a constituent may be exploited. Chapter 3 describes the blending of polyaniline with conventional thermoplastics. Processing these polyblends into foams yielded a porous conductive material. The effect of blend composition and processing parameters on the resulting porous morphology and electrical conductivity was investigated. These findings represent the first systematic study of porous conductive polymer blends. In Chapter 4, multilayer electroactive polymer actuators consisting of polypyrrole films electropolymerized on a passive polymer membrane core were harnessed as actuators. The membrane is vital in the transport of ionic species and largely dictates the stiffness of the layered configuration. The impact of the mechanical properties of the membrane on the actuation response of polypyrrole-based trilayer bending actuators was investigated. Candidate materials with distinct morphologies were identified and their mechanical properties were evaluated. These results indicated that polyvinylidene difluoride membranes were superior to the other candidates. An electrochemical synthesis procedure was proposed, and the design of a novel polymerization vessel was reported. These facilities were utilized to prepare actuators under a variety of synthesis conditions to investigate the impact of conductive polymer morphology on the electromechanical response. Characterization techniques were implemented to quantitatively assess physical and electrochemical properties of the layered composite. Chapter 5 proposes a new unified multiphysics model that captures the electroactive actuation response inherent to conductive polymer trilayer actuators. The main contribution of this investigation was the proposal and development of a new hybrid model that unifies concepts from charge transport and electrochemomechanical models. The output of the proposed model was compared with published data and shown to be accurate to within 10%. Finally, Chapter 6 demonstrated the application of these materials for use as precision mirror positioners in adaptive optical systems.

Price, Aaron David

140

Ionic conductivity through thermoresponsive polymer gel: ordering matters.  

Science.gov (United States)

Thermoreversible polymer gel has been prepared using PEO-PPO-PEO block copolymer (Pluronic F77) which self-assembles into different microcrystalline phases like cubic, 2D-hexagonal, and lamellar. Addition of electrolyte (LiI/I(2)) converts the gel into a polymer gel electrolyte (PGE) which exhibits microphase-dependent ionic conductivity. The crystalline phases have been identified by SAXS as a function of the polymer concentration. It is found that the optimum value for the ionic conductivity (?1 × 10(-3) S x cm(-1)) is achieved in the Im3m phase due to faster diffusion of ions through the 3D-interconnected micellar nanochannels. This fact is further supported by FTIR study, ionic transference number, and diffusion coefficient measurements. PMID:22070374

Soni, Saurabh S; Fadadu, Kishan B; Gibaud, Alain

2012-01-10

 
 
 
 
141

Maximum conductivity of packed nanoparticles and their polymer composites.  

Science.gov (United States)

Adding conductive fillers to nonconductive polymers is a common way to make soft conductive materials such as conductive adhesives. An important issue is how to achieve high volume conductivity with acceptable mechanical performance. Two questions pertaining to this issue were studied in this paper. One question was whether the maximum conductivity benefits from larger or smaller particle sizes. The second was what is the maximum achievable conductivity. One incentive for this work is the recent availability of nanomaterials that provide opportunities to make conductive composites using much smaller particles than in the past. We found that the conductivity of platinum, carbon black, and silver particles in their polyurethane composites did not vary greatly with particle size (from micrometer to nanometer range). What was unexpected was that in all the composite examples, the highest conductivity achieved was only on the order of 1% of that of the pure bulk conductive materials. Further experiments to emulate these conductive composites with platinum, carbon black, copper, and nickel particles without polymer matrix showed similar results, indicating the issue is not simply dispersion homogeneity, nano versus macro particles, particle connectivity/percolation, or the presence of the matrix materials. We interpret this to mean that the composite systems are intrinsically limited by the contact between filler particles. PMID:20355760

Untereker, Darrel; Lyu, Suping; Schley, James; Martinez, Gonzalo; Lohstreter, Lance

2009-01-01

142

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)

143

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

144

Physical properties of Li ion conducting polyphosphazene based polymer electrolytes  

Energy Technology Data Exchange (ETDEWEB)

We report a systematic study of the transport properties and the underlying physical chemistry of some polyphosphazene (PPhz)-based polymer electrolytes. We synthesized MEEP and variants which employed mixed combinations of different length oxyethylene side-chains. We compare the conductivity and ion-ion interactions in polymer electrolytes obtained with lithium triflate and lithium bis(trifluoromethanesulfonyl)imide (TFSI) salts added to the polymer. The combination of the lithium imide salt and MEEP yields a maximum conductivity of 8 x 10{sup -5} {Omega}{sup -1} cm{sup -1} at room temperature at a salt loading of 8 monomers per lithium. In one of the mixed side-chain variations, a maximum conductivity of 2 x 10{sup -4} {Omega}{sup -1} cm{sup -1} was measured at the same molar ratio. Raman spectral analysis shows some ion aggregation and some polymer - ion interactions in the PPhz-LiTFSI case but much less than observed with Li CF{sub 3}SO{sub 3}. A sharp increase in the Tg as salt is added corresponds to concentrations above which the conductivity significantly decreases and ion associations appear.

Sanderson, S.; Zawodzinski, T.; Hermes, R.; Davey, J.; Dai, Hongli

1996-12-31

145

Structure, morphology and ionic conductivity of solid polymer electrolyte  

International Nuclear Information System (INIS)

Graphical abstract: Two-dimensional atomic force image of pure polyethylene oxide presents a crystallized network of regular spherulites developing spirals and branches of well distributed surface contours. Highlights: ? The incorporation of ceria significantly modifies the morphology of polyethylene oxide (PEO)-KI complex. ? The ionic conductivity increases by about two orders of magnitude by the addition of ceria nanoparticles. ? Ionic conductivity as a function of ceria concentration reveals two maxima. ? Grain boundary effect of nanofiller, strong Lewis acid-base interaction between PEO and nanosized ceria, change of conformation of PEO molecule and epitaxial effect of ceria nanoparticles control the ionic conductivity of composite polymer electrolyte. -- Abstract: Polyethylene oxide (PEO) complexed with potassium iodide (KI) is synthesized to investigate the ionic conductivity of alkaline based polymer electrolytes. The structural and morphological characterizations of the nanocomposite polymer electrolytes are performed by X-ray diffractometry (XRD), atomic force microscopy (AFM), differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) measurements. The ionic conductivity increases with the increase of KI concentration up to about 20 wt.%. The effect of nanosized ceria (CeO2 ? 10 nm) fillers on ionic conductivity in PEO-KI polymer electrolyte is also carried out, keeping PEO to KI wt.% ratio 80:20 and 85:15. The result reveals that the addition of ceria nanoparticles enhances the conductivity by two orders of magnitude. The presence of ceria at the highest concentration induces the same molecular environment within PEO chain as that of undoped PEO. Temperature dependence of ionic conductivity follows Arrhenius mechanism.

146

Structure, morphology and ionic conductivity of solid polymer electrolyte  

Energy Technology Data Exchange (ETDEWEB)

Graphical abstract: Two-dimensional atomic force image of pure polyethylene oxide presents a crystallized network of regular spherulites developing spirals and branches of well distributed surface contours. Highlights: {yields} The incorporation of ceria significantly modifies the morphology of polyethylene oxide (PEO)-KI complex. {yields} The ionic conductivity increases by about two orders of magnitude by the addition of ceria nanoparticles. {yields} Ionic conductivity as a function of ceria concentration reveals two maxima. {yields} Grain boundary effect of nanofiller, strong Lewis acid-base interaction between PEO and nanosized ceria, change of conformation of PEO molecule and epitaxial effect of ceria nanoparticles control the ionic conductivity of composite polymer electrolyte. -- Abstract: Polyethylene oxide (PEO) complexed with potassium iodide (KI) is synthesized to investigate the ionic conductivity of alkaline based polymer electrolytes. The structural and morphological characterizations of the nanocomposite polymer electrolytes are performed by X-ray diffractometry (XRD), atomic force microscopy (AFM), differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) measurements. The ionic conductivity increases with the increase of KI concentration up to about 20 wt.%. The effect of nanosized ceria (CeO{sub 2} {approx} 10 nm) fillers on ionic conductivity in PEO-KI polymer electrolyte is also carried out, keeping PEO to KI wt.% ratio 80:20 and 85:15. The result reveals that the addition of ceria nanoparticles enhances the conductivity by two orders of magnitude. The presence of ceria at the highest concentration induces the same molecular environment within PEO chain as that of undoped PEO. Temperature dependence of ionic conductivity follows Arrhenius mechanism.

Dey, Arup; Karan, S. [Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032 (India); Dey, Ashis [Department of Chemistry, Sarsuna College, Sarsuna Upanagari, Kolkata 700061 (India); De, S.K., E-mail: msskd@iacs.res.in [Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032 (India)

2011-11-15

147

Electro-optic waveguide with conductive chromophore contained polymer cladding  

Science.gov (United States)

Polymer electro-optic (EO) waveguides are key component of high performance electro-optic switches. Recently, EO chromophore and host polymer matrix are investigated to get high EO coefficient (r33) and fabricate waveguide structures. To realize high r33, chromophore density in host polymer matrix must be increased. However, high loading density results in lowering of resistivity of EO material. It becomes a problem when chromophore is poled in waveguide structure and EO modulator is worked at low frequency. In this case, EO material is sandwiched by other cladding materials but usually these materials have low conductivity compared with EO material. It means effective electric field applied to EO material and r33 is reduced by cladding material layers. To improve these difficulties, we proposed new chromophore contained polymer material as cladding material of EO waveguide. Addition of EO chromospheres (6 wt %) increase conductivity to 106~107 ?•m. The value is comparable or above to EO materials. We also present fabrication results of EO ridge waveguide with the chromophore contained cladding polymer.

Yamamoto, Kazuhiro; Yu, Feng; Li, Lu; Yokoyama, Shiyoshi; Otomo, Akira; Yasui, Kei; Ozawa, Masaaki

2013-03-01

148

Excimer Laser Induced Electrical Conductivity and Nanostructures in Polymers.  

Science.gov (United States)

The generation of substantial electrical conductivity in high temperature polymers and thin film C_ {60} by means of KrF (248 nm) excimer laser irradiation has been investigated. Formation of both laser ablated surface structures and laser induced electrically conducting wires in polymers with nanometer dimensions is also demonstrated. The electrical conductivity of polymers has been changed by up to 18 orders of magnitude by laser irradiation, obtaining values exceeding 10 Omega^ {-1} cm^{-1} . The conducting material consists of graphitized carbon clusters whose size varies from 2-50 nm. The conduction mechanism is phonon assisted variable range hopping. The large change in the electrical conductivity is an example of a three dimensional percolative metal-insulator phase transition. The critical volume fraction is determined to be Phi_{rm c} = 0.30 +/- 0.05 and the critical exponent is t = 2.2 +/- 0.4. The electrical conductivity of thin film C _{60} has been altered by more than seven orders of magnitude with laser irradiation, obtaining values of 1 Omega^{ -1} cm^{-1}. The threshold for KrF laser ablation of C_{60 } is determined to be 20 +/- 2 mJ/cm^2.. Modification of the surface morphology and the electrical conductivity of polymers with high spatial resolution using excimer lasers has also been achieved. Using holographic techniques with a KrF excimer laser, periodic lines structures with periods ranging from 166 nm to 950 nm were ablated into polyimide (Kapton^{rm TM }) and polybenzimidazole (PBI). The nonlinear nature of laser ablation permits linewidths as small as 30 nm to be obtained, exceeding the resolution expected from linear optics. These experiments establish a new spatial resolution limit for laser ablation and illustrate the dependence of resolution on material properties. This technique was combined with the ability to modify the electrical conductivity of polymers to produce an array of permanently electrically conducting wires in polyimide with a 0.5 ?m width and a 0.9 mu m period. The electrical conductivity of these submicron wires exceeded 1 Omega^ {-1} cm^{-1}. .

Phillips, Harvey Monroe

149

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

150

Poly-beta-pinene, a Novel Nonconjugated Conductive Polymer  

Science.gov (United States)

Electrical conductivity in a novel nonconjugated conductive polymer, poly-beta-pinene, has been measured as a function of iodine doping. The conductivity increases about ten orders of magnitude to a maximum value ˜ 0.01 S/cm. The molar concentration of iodine corresponding to saturation is ˜ 0.8. The optical absorption measurements after light doping have shown two peaks: one at 4.1 eV and the other at 3.1 eV. The first peak is due to the radical cation and the second due the charge-transfer between the double bond and the dopant. As observed in other nonconjugated conductive polymers, the second peak becomes broader and undergoes a red-shift upon higher doping [1,2]. The FTIR spectroscopic studies have shown that the C=C stretching vibration at 1610 cm-1 and the =C-H bending vibration band at 728 cm-1 decrease upon doping as observed in other nonconjugated conductive polymers. Preliminary measurements have shown large quadratic electro-optic effects in this material. 1. M. Thakur, J. Macromol. Sci.-PAC,2001,A38(12),1337. 2. M. Thakur, S. Khatavkar and E.J. Parish, J. Macromol. Sci.-PAC,2003,A40(12),1397.

Thakur, Mrinal; Vippa, Prakash; Rajagopalan, Harish

2004-03-01

151

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

152

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

DEFF Research Database (Denmark)

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

Cooke, David

153

Electrosynthetically patterned conducting polymer films for investigation of neural signaling  

Science.gov (United States)

The ion-mediated conduction and versatility of device fabrication of conducting polymers provide a route to the study of neural signaling. Patterned junctions of conducting polypyrrole have been electropolymerized on commercially available microelectrode arrays, with typical dimensions 200 ?m between electrodes, each electrode being 30 ?m in diameter. Tetrabutylammonium perchlorate or sodium p-toluenesulfonate were used as electrolyte/counterion in the organic solvent. Individual polypyrrole junctions, when synthesized and connected in a three-electrode configuration, exhibit current-switching behavior analogous to neural weighting. Junctions copolymerized with thiophene exhibit current rectification and the nonlinear current-voltage behavior requisite for complex neural systems (i.e., the activation function).

Simon, Daniel T.; Carter, Sue A.

2006-05-01

154

Synthesis and characterization of porous polyaniline conductive polymers  

Science.gov (United States)

Polyaniline conductive polymers exhibit great potential for linear actuator applications. Many recent studies report methods to develop polyaniline-based materials with increased mechanical properties, electrical conductivity, and faster response time during actuation. In this study, porous blends of poly(methylmethacrylate) and polyaniline are processed using a two phase batch foaming setup. The effect of materials, processing, and system parameters on the physical properties of the resulting cellular structure are investigated. Hence, the effect of density and cell morphology on the electrical conductivity is elucidated.

Price, Aaron D.; Naguib, Hani E.

2007-04-01

155

Development of the conductive polymer matrix composite with low concentration of the conductive filler  

Energy Technology Data Exchange (ETDEWEB)

Composite particles with ultra-high molecular polyethylene (UHMWPE) core and carbon black (CB) or carbon nanotube (CNT) shell were produced by particle composite system, then molded into conductive polymer composites. Morphology of these composite particles was investigated by scanning electron microscopy (SEM). Matrix particles are coated with CB or CNTs very well. And CNTs are not being cut short. The results of electrical behavior study show that these polymer composites have low percolation threshold. Conductive networks of CB and CNT were seen by optical microscopy. Related mechanism is discussed.

Hao Xiangyang [School of Materials Sciences and Technology, China University of Geosciences, Beijing 100083 (China); Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)], E-mail: haoxy@tsinghua.edu.cn; Gai Guosheng; Yang Yufen [Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Zhang Yihe [School of Materials Sciences and Technology, China University of Geosciences, Beijing 100083 (China); Nan Cewen [Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)

2008-05-15

156

Bioaffinity sensing using biologically functionalized conducting-polymer nanowire.  

Science.gov (United States)

A simple, one-step method for fabricating single biologically functionalized conducting-polymer (polypyrrole) nanowire on prepatterned electrodes and its application to biosensing was demonstrated. The biologically functionalized polypyrrole was formed by the electropolymerization of an aqueous solution of pyrrole monomer and the model biomolecule, avidin- or streptavidin-conjugated ZnSe/CdSe quantum dots, within 100 or 200 nm wide by 3 mum long channels between gold electrodes on prefabricated silicon substrate. When challenged with biotin-DNA, the avidin- and streptavidin-polypyrrole nanowires generated a rapid change in resistance to as low as 1 nM, demonstrating the utility of the biomolecule-functionalized nanowire as biosensor. The method offers advantages of direct incorporation of functional biological molecules into the conducting-polymer nanowire during its synthesis, site-specific positioning, built-in electrical contacts, and scalability to high-density nanoarrays over the reported silicon nanowire and carbon nanotube biosensors. PMID:15643853

Ramanathan, Kumaran; Bangar, Mangesh A; Yun, Minhee; Chen, Wilfred; Myung, Nosang V; Mulchandani, Ashok

2005-01-19

157

Ethanol Gas Sensing Characteristics of Conducting Polymer Sensor Using Impedance  

Energy Technology Data Exchange (ETDEWEB)

The polypyrrole and polyaniline thin film sensors which were made by chemical polymerization were employed to detect ethanol gas. With a single sensor element we can obtain characteristic patterns of behaviour across a very wide frequency range when measuring either resistance or capacitance. Impedance spectroscopy was employed to study the gas sensing behavior of both capacitance and resistance based sensors with conducting polymer as the active sensing element. (author). 9 refs., 6 figs., 1 tab.

Lee, K.M.; Yu, J.B.; Jun, H.K.; Lee, B.S.; Lee, D.D.; Huh, J.S. [Kyungpook National University, Taegu (Korea)

2003-03-01

158

High sensitivity DNA detection using gold nanoparticles and conducting polymers  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The detection and quantitation of specific nucleic acid (NA) sequences continues to grow in importance driven by issues ranging from personalized medicine to companion diagnostics such as antibiotic selection for infectious diseases. In order to enhance the sensitivity of electrochemical detection of DNA, novel conducting polymer- metal nanoparticle composites have been created. An electrode modified with nanostructured gold (AuNP-elec) has been used to increase the surface of the electrode a...

Spain, Elaine

2011-01-01

159

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

160

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

Energy Technology Data Exchange (ETDEWEB)

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 {proportional_to}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.

Mechau, Norman; Schmechel, Roland [Forschungszentrum Karlsruhe, Institut of Nanotechnology, 76021 Karlsruhe (Germany); Prodi-Schwab, Anna [Degussa AG, Science to Business Center, 45764 Marl (Germany)

2007-07-01

 
 
 
 
161

A practical multilayered conducting polymer actuator with scalable work output  

Science.gov (United States)

Household assistance robots are expected to become more prominent in the future and will require inherently safe design. Conducting polymer-based artificial muscle actuators are one potential option for achieving this safety, as they are flexible, lightweight and can be driven using low input voltages, unlike electromagnetic motors; however, practical implementation also requires a scalable structure and stability in air. In this paper we propose and practically implement a multilayer conducting polymer actuator which could achieve these targets using polypyrrole film and ionic liquid-soaked separators. The practical work density of a nine-layer multilayer actuator was 1.4 kJ m-3 at 0.5 Hz, when the volumes of the electrolyte and counter electrodes were included, which approaches the performance of mammalian muscle. To achieve air stability, we analyzed the effect of air-stable ionic liquid gels on actuator displacement using finite element simulation and it was found that the majority of strain could be retained when the elastic modulus of the gel was kept below 3 kPa. As a result of this work, we have shown that multilayered conducting polymer actuators are a feasible idea for household robotics, as they provide a substantial practical work density in a compact structure and can be easily scaled as required.

Ikushima, Kimiya; John, Stephen; Yokoyama, Kazuo; Nagamitsu, Sachio

2009-09-01

162

Critical Dependence of Polarization Phenomena on Conductivity in Ferroelectric Polymers  

Directory of Open Access Journals (Sweden)

Full Text Available Experimentally obtained data on the polarization dynamics in polyvinylidene fluoride, a typical ferroe-lectric polymer, are analyzed during initial poling, short circuiting and polarization switching. Considering a two-component structure of the samples, namely, presence of ferroelectric and non-ferroelectric phases, it is shown that value and stability of the ferroelectric polarization significantly depend on conductivity and space charges. Application of a simple two-layer theoretical model with an explicit conductivity allowed ex-plaining such important features, as slow development and switching of the ferroelectric polarization and a partial back-switching of the already formed polarization after short-circuiting of the sample.

S.N. Fedosov

2014-01-01

163

Ab-initio study of napthelene based conducting polymer  

International Nuclear Information System (INIS)

In this paper, we have identified structural and electronic properties of conducting polymers by using DFT based ATK-VNL ab-initio tool. Naphthalene derivative structures were stabilized by varying the bond length between two atoms of the molecule C-N and C-C. We have also studied the molecular energy spectrum of naphthalene derivatives and found the HOMOLUMO for the same. A comparison of structural and electronic properties of naphthalene derivatives by attaching the functional group of amine, have been performed and found that they show good semi conducting properties

164

Ab-initio study of napthelene based conducting polymer  

Energy Technology Data Exchange (ETDEWEB)

In this paper, we have identified structural and electronic properties of conducting polymers by using DFT based ATK-VNL ab-initio tool. Naphthalene derivative structures were stabilized by varying the bond length between two atoms of the molecule C-N and C-C. We have also studied the molecular energy spectrum of naphthalene derivatives and found the HOMOLUMO for the same. A comparison of structural and electronic properties of naphthalene derivatives by attaching the functional group of amine, have been performed and found that they show good semi conducting properties.

Ruhela, Ankur [Advanced Materials Research Group, Computational Nanoscience and Technology Lab (CNTL), ABV-Indian Institute of Information Technology and Management, Gwalior -474010, India and Amity Institute of Nanotechnology, Amity University, Noida-201303 (India); Kanchan, Reena, E-mail: reena.kanchan1977@gmail.com [Department of Chemistry, Jiwaji University, Gwalior-474001 (India); Srivastava, Anurag [Advanced Materials Research Group, Computational Nanoscience and Technology Lab (CNTL), ABV-Indian Institute of Information Technology and Management, Gwalior -474010 (India); Sinha, O. P. [Amity Institute of Nanotechnology, Amity University, Noida-201303 (India)

2014-04-24

165

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.

166

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

Science.gov (United States)

Both cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs) are nanoscale cellulose fibers that have shown reinforcing effects in polymer nanocomposites. CNCs and CNFs are different in shape, size and composition. This study systematically compared their morphologies, crystalline structure, dispersion properties in polyethylene oxide (PEO) matrix, interactions with matrix, and the resulting reinforcing effects on the matrix polymer. Transparent PEO/CNC and PEO/CNF nanocomposites comprising up to 10 wt % nanofibers were obtained via solution casting. Scanning electron microscopy (SEM), wide-angle X-ray diffraction (WXRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), dynamic mechanical analyzer (DMA), and tensile testing were used to examine the above-mentioned properties of nanocellulose fibers and composites. At the same nanocellulose concentration, CNFs led to higher strength and modulus than did CNCs due to CNFs' larger aspect ratio and fiber entanglement, but lower strain-at-failure because of their relatively large fiber agglomerates. The Halpin-Kardos and Ouali models were used to simulate the modulus of the composites and good agreements were found between the predicted and experimental values. This type of systematic comparative study can help to develop the criteria for selecting proper nanocellulose as a biobased nano-reinforcement material in polymer nanocomposites. PMID:23521616

Xu, Xuezhu; Liu, Fei; Jiang, Long; Zhu, J Y; Haagenson, Darrin; Wiesenborn, Dennis P

2013-04-24

167

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

168

Copper shell networks in polymer composites for efficient thermal conduction.  

Science.gov (United States)

Thermal management of polymeric composites is a crucial issue to determine the performance and reliability of the devices. Here, we report a straightforward route to prepare polymeric composites with Cu thin film networks. Taking advantage of the fluidity of polymer melt and the ductile properties of Cu films, the polymeric composites were created by the Cu metallization of PS bead and the hot press molding of Cu-plated PS beads. The unique three-dimensional Cu shell-networks in the PS matrix demonstrated isotropic and ideal conductive performance at even extremely low Cu contents. In contrast to the conventional simple melt-mixed Cu beads/PS composites at the same concentration of 23.0 vol %, the PS composites with Cu shell networks indeed revealed 60 times larger thermal conductivity and 8 orders of magnitude larger electrical conductivity. Our strategy offers a straightforward and high-throughput route for the isotropic thermal and electrical conductive composites. PMID:24160688

Yu, Seunggun; Lee, Jang-Woo; Han, Tae Hee; Park, Cheolmin; Kwon, Youngdon; Hong, Soon Man; Koo, Chong Min

2013-11-27

169

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

170

Ion conductivity and transport by porous coordination polymers and metal-organic frameworks.  

Science.gov (United States)

Ion conduction and transport in solids are both interesting and useful and are found in widely distinct materials, from those in battery-related technologies to those in biological systems. Scientists have approached the synthesis of ion-conductive compounds in a variety of ways, in the areas of organic and inorganic chemistry. Recently, based on their ion-conducting behavior, porous coordination polymers (PCPs) and metal-organic frameworks (MOFs) have been recognized for their easy design and the dynamic behavior of the ionic components in the structures. These PCP/MOFs consist of metal ions (or clusters) and organic ligands structured via coordination bonds. They could have highly concentrated mobile ions with dynamic behavior, and their characteristics have inspired the design of a new class of ion conductors and transporters. In this Account, we describe the state-of-the-art of studies of ion conductivity by PCP/MOFs and nonporous coordination polymers (CPs) and offer future perspectives. PCP/MOF structures tend to have high hydrophilicity and guest-accessible voids, and scientists have reported many water-mediated proton (H(+)) conductivities. Chemical modification of organic ligands can change the hydrated H(+) conductivity over a wide range. On the other hand, the designable structures also permit water-free (anhydrous) H(+) conductivity. The incorporation of protic guests such as imidazole and 1,2,4-triazole into the microchannels of PCP/MOFs promotes the dynamic motion of guest molecules, resulting in high H(+) conduction without water. Not only the host-guest systems, but the embedding of protic organic groups on CPs also results in inherent H(+) conductivity. We have observed high H(+) conductivities under anhydrous conditions and in the intermediate temperature region of organic and inorganic conductors. The keys to successful construction are highly mobile ionic species and appropriate intervals of ion-hopping sites in the structures. Lithium (Li(+)) and other ions can also be transported. If we can optimize the crystal structures, this could offer further improvements in terms of both conductivity and the working temperature range. Another useful characteristic of PCP/MOFs is their wide application to materials fabrication. We can easily prepare heterodomain crystal systems, such as core-shell or solid solution. Other anisotropic morphologies (thin film, nanocrystal, nanorod, etc.,) are also possible, with retention of the ion conductivity. The flexible nature also lets us design morphology-dependent ion-conduction behaviors that we cannot observe in the bulk state. We propose (1) multivalent ion and anion conductions with the aid of redox activity and defects in structures, (2) control of ion transport behavior by applying external stimuli, (3) anomalous conductivity at the hetero-solid-solid interface, and (4) unidirectional ion transport as in the ion channels in membrane proteins. In the future, scientists may use coordination polymers not only to achieve higher conductivity but also to control ion behavior, which will open new avenues in solid-state ionics. PMID:23730917

Horike, Satoshi; Umeyama, Daiki; Kitagawa, Susumu

2013-11-19

171

Radiation cross-linking of PTC conductive polymers  

International Nuclear Information System (INIS)

An electrical device comprising a PTC conductive polymer is irradiated so that it is very highly cross-linked. A dosage of at least 50 Mrads, preferably at least 80 Mrads, especially at least 120 Mrads is used except that where the device includes planar electrodes which are present during irradiation the minimum dose is 120 Mrads. In this way, for example, it is possible to make a circuit protection device which will continue to provide effective protection even after repeated exposure to a voltage of 200 volts. A PTC protection device may be produced by moulding carbon loaded polymer round three electrodes the centre one of which is then removed to leave an aperture between the other two electrodes. (author)

172

Thermal Conductivity of Polymer Composite poypropilene-Sand  

International Nuclear Information System (INIS)

Thermal conductivity composite materials polypropylene (PP)-sand have been investigated. PP composite with sand to increase thermal conductivity from the polymer. The composite in this observation is done by mixing matrix (PP melt flow 2/10)and filler sand)by means tool labo plastomil. The result of thermal conductivity is composite of PP-sand which is obtained increase and followed by the raising of filler particle volume fraction. The analysis of thermal conductivity based on the model Cheng and Vachon, model Lewis and Nielsen where this model has the function to support experiment finding. It is proved that Lewis' and Nielsen's model almost approach experiment result. And then thermal conductivity raising will be analyzed by the model of pararel-series conductive with the two (2)phases system. It is showed that sand in PP MF 2 composite have the big role to increase the thermal conductivity than sand in PP MF 10 composition, but it is not easy to shape conductive medium

173

Nanocrystal doped matrixes  

Science.gov (United States)

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

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

2010-01-12

174

Effect of dose on radiation-induced conductivity in polymers  

International Nuclear Information System (INIS)

Numerical simulation of radiation-induced conductivity in polymers upon long-term irradiation on the basis of the generalized Rose-Fowler-Vaisberg model, which allows for both dipolar carrier transport and generation of radiation traps during irradiation, was performed. The unusual properties of radiation-induced conductivity, such as the appearance of a maximum on current transients, the absence of a steady state, and a substantial difference between these curves for the first and subsequent irradiation, are rationalized in terms of the formation of free radicals, the major feature of radiolysis in the chemical aspect. This interpretation does not require the involvement of degradation or crosslinking processes, unlike other interpretations that appear in the literature. With the use of low-density polyethylene as an example, it was shown that radiation-induced conductivity both upon pulse and continuous irradiation can satisfactorily be described with the unified set of parameters of the generalized Rose-Fowler-Vaisberg model

175

Ultrahigh capacitance of nanoporous metal enhanced conductive polymer pseudocapacitors  

Science.gov (United States)

A high energy density is critical for supercapacitors to supersede conventional batteries for the applications where both high power and high energy are demanded. Here we report nanoporous metal/conductive polymer hybrid electrodes fabricated by electrochemically plating conductive polypyrrole into nanoporous channels of a dealloyed nanoporous metal. The low electric resistance and open porosity of the nanoporous metal give rise to excellent conductivity of electrons and ions and hence dramatically improved electrochemical performances of the pseudocapacitive polypyrrole. Supercapacitors based on the hybrid electrodes show an ultrahigh energy density of ˜100 Wh kg-1 in a three-electrode, comparable to NiMH batteries, as well as high power density of ˜57 kW kg-1. Cycling stability measurements demonstrate that the hybrid electrode can retain 85% of the maximum capacitance after 3000 cycles and the degeneration is mainly caused by the dissolution of polypyrrole during charge/discharge cycling.

Hou, Ying; Chen, Luyang; Zhang, Ling; Kang, Jianli; Fujita, Takeshi; Jiang, Jianhua; Chen, Mingwei

2013-03-01

176

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

177

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.

178

Fabrication and characterization of solid-state, conducting polymer actuators  

Energy Technology Data Exchange (ETDEWEB)

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

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

2004-01-01

179

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

180

Polymer-dispersed liquid crystal devices using highly conducting polymers as electrodes  

Science.gov (United States)

Flexible all-organic polymer-dispersed liquid crystal (PDLC) devices were fabricated by using highly transparent and conductive poly(3,4-ethylenedioxy thiophene): p-toluene sulfonate (PEDOT:PTS) films, as electrode layers. These conductive PEDOT:PTS films have a high transparency up to 80%, and possess a very low sheet resistance of 100?sq-1 at 100nm thickness. We report on the fabrication and characterization of a PDLC device using a highly conductive PEDOT:PTS for the electrodes and demonstrate its superior performance relative to that of a similar device using the indium tin oxide layer as the electrodes.

Kim, Jin-Yeol; Woo, Hak-Yong; Baek, Ji-Woong; Kim, Tae-Wook; Song, Eun-Ah; Park, Su-Cheol; Ihm, Dae-Woo

2008-05-01

 
 
 
 
181

Utilization of novel bithiazole based conducting polymers in electrochromic applications  

Science.gov (United States)

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.

Camurlu, Pinar; Gültekin, Cemil

2012-02-01

182

Alloy/conducting-polymer composite electrodes: electrolytes, cathodes, and morphology  

Science.gov (United States)

Composites comprising alkali metal alloys and alkali metal doped conductive polymers constitute a class of electrode materials useful in rechargeable cells. Composite electrodes made with poly( p-phenylene) (PPP) and polyacetylene (PA) exhibit high rechargeability for donor doping (cation insertion) in ether electrolytes such as NaPF 6 in 1,2-dimethoxyethane (DME) and LiPF 6 in 2-methyltetrahydrofuran (MTHF), plus rechargeability, at restricted potentials, in solvents such as sulfolane and benzonitrile. Na?Pb, Li?Pb, and Li?Al alloys, formed as composites with PPP and PA, have been cycled exhaustively with excellent charge capacity retention. These composites form rechargeable cells with a variety of cation-inserting cathodes. In particular, balanced cells having Na?Pb/PPP anodes and NaCoO 2 cathodes have been cycled 250 times with little capacity loss. The good performance of these composites is due, in part, to the basic fibrillar morphology of the polymer, which becomes evident during cycling. After several cycles, the composites possess the fibrillar structure of pure polymer electrodes, with crystalline alloy uniformly distributed on or in the fibrils in particles of less than 0.2 ?m. This structure, particularly when the fibrils are swollen with electrolyte, facilitates rapid transport of ions and electronic charge throughout the electrode.

Maxfield, M.; Jow, T. R.; Sewchok, M. G.; Shacklette, L. W.

183

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)

184

NMR, electrical relaxation, and high pressure electrical conductivity in ion conducting polymers. Interim technical report  

Energy Technology Data Exchange (ETDEWEB)

Recent nuclear magnetic resonance (NMR), electrical relaxation, and high pressure electrical conductivity studies of ion conducting polymers are reviewed. Most of the work discussed is that concerned with poly(ethylene oxide) (PEO) though some recent results concerning poly(vinyl acetate) are also described. A survey of experimental 1H, 7Li, 19F, and 23Na NMR data for ion conducting polymers based on PEO reveals some features that are commonly observed in supersonic solids, such as motional narrowing in the temperature region of enhanced conductivity. The NMR activation energies are generally lower than those for conductivity, indicating the presence of localized motional processes. Previous electrical relaxation data along with new results for PE04.5:NaI and PE04.5:LiCF3S03 make it clear that PEO complexed with different salts exhibits different electrical relaxation spectra. Changes in chain structure are detected along with multiphase behavior. Also, new results are presented for the effect of high pressure on the electrical conductivity of poly(propylene oxide) complexed with alkali metal salts. Those results eliminate some ambiguities associated with previous high pressure electrical conductivity studies of PEO.

Fontanella, J.J.; Wintersgill, M.C.; Greenbaum, S.G.

1984-05-01

185

Na+ Ion Conducting Hot-pressed Nano Composite Polymer Electrolytes  

Scientific Electronic Library Online (English)

Full Text Available SciELO Portugal | Language: English Abstract in english 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 traditi [...] onal solution cast method. The dispersal of SiO2 in SPE host: (75PEO: 25NaPO3), a conductivity enhancement of an order of magnitude achieved in NCPE film: [93 (75PEO: 25NaPO3): 7 SiO2]. This has been referred to as Optimum Conducting Composition (OCC). Material characterizations have been done with the help of XRD, SEM and DSC techniques. The ion transport behaviour in hot-pressed NCPEs has been discussed on the basis of experimental measurements on some basic ionic parameters viz. conductivity (?), ionic mobility (?), mobile ion concentration (n) and ionic transference number (t ion). The temperature dependent conductivity studies have been done to compute the activation energy (Ea) values from the 'log s - 1/T' Arrhenius plots. The ion conducting solid state polymeric battery was fabricated and cell-potential discharge characteristics have been studied at different load conditions.

Angesh, Chandra; Archan, Chandra; Kiran, Thakurb.

186

Na+ Ion Conducting Hot-pressed Nano Composite Polymer Electrolytes  

Scientific Electronic Library Online (English)

Full Text Available SciELO Portugal | Language: English Abstract in english 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 traditi [...] onal solution cast method. The dispersal of SiO2 in SPE host: (75PEO: 25NaPO3), a conductivity enhancement of an order of magnitude achieved in NCPE film: [93 (75PEO: 25NaPO3): 7 SiO2]. This has been referred to as Optimum Conducting Composition (OCC). Material characterizations have been done with the help of XRD, SEM and DSC techniques. The ion transport behaviour in hot-pressed NCPEs has been discussed on the basis of experimental measurements on some basic ionic parameters viz. conductivity (?), ionic mobility (?), mobile ion concentration (n) and ionic transference number (t ion). The temperature dependent conductivity studies have been done to compute the activation energy (Ea) values from the 'log s - 1/T' Arrhenius plots. The ion conducting solid state polymeric battery was fabricated and cell-potential discharge characteristics have been studied at different load conditions.

Angesh, Chandra; Archan, Chandra; Kiran, Thakurb.

2012-03-01

187

Na+ Ion Conducting Hot-pressed Nano Composite Polymer Electrolytes  

Directory of Open Access Journals (Sweden)

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

Angesh Chandra

2012-03-01

188

A facile route to semiconductor nanocrystal-semiconducting polymer complex using amine-functionalized rod-coil triblock copolymer as multidentate ligand  

International Nuclear Information System (INIS)

A facile strategy affording an intimate nanocomplex of an amine-containing rod-coil triblock copolymer poly(2-(dimethylamino)ethylmethacrylate)-poly(fluorene)-poly(2-(dimethyl amino) ethylmethacrylate) and CdSe nanocrystals is presented. Ligand exchange is observed by 31P NMR. TEM and UV-vis absorption results indicate the CdSe NCs have a good dispersion in the conjugated polymer. Also, the PL spectra show photoinduced charge transfer has been facilitated by the complex formation

189

Electrical Conductivity in Polymer Blends/ Multiwall Carbon Nanotubes  

Science.gov (United States)

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.

Kulkarni, Ajit R.; Bose, Suryasarathi; Bhattacharyya, Arup R.

2008-10-01

190

Transistor-type Devices Based on Conducting Polymers  

Science.gov (United States)

All polymer, flexible transistor type devices have been constructed following the line patterning method(A.G. MacDiarmid, Agnew. Chem. Int. Ed. 40, 2581 (2001)), using a mixture of poly(3,4-ethylenedioxythiophene) (PEDOT) and polystyrene sulfonic acid (PSSA) or in situ polymerized polyaniline doped with HCl as the gate, source, and drain electrodes, and as well as the active material. For polyaniline devices the resistance reversibly increases 5 orders of magnitude in the polymeric material between the source and drain electrodes as a voltage is applied to the gate electrode. For PEDOT-PSSA devices this resistance increases 3 orders of magnitude with the same applied gate voltage. With application of the gate voltage, the large increase in resistivity, the change in ? (T) functional form, and the strong temperature dependence of ? (T) imply a change in conduction mechanism. The charge conduction mechanisms and roles of ionic motion will be discussed.

Hsu, F. C.; Smallfield, J. A. O.; Joo, J.; Lu, J.; MacDiarmid, A. G.; Epstein, A. J.

2002-03-01

191

On the Electronic Transport Mechanism in Conducting Polymer Nanofibers  

CERN Document Server

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

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

2005-01-01

192

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

193

Synthesis and evaluation of semi-conductive polymer compositions  

International Nuclear Information System (INIS)

A semi-conductive polymer composition in which micronized particulate conductive filler such as copper or graphite is dispersed in a polymeric component which is of an essentially amorphous thermoplastic resin such as poly methyl methacrylate was prepared. These molding powders of polymethylmethacrylate were prepared by suspension polymerization of methylmethacrylate monomer in presence of these conductors. The prepared molding powder contains 4.8% and 40.44% by volume (with respect to PMMA) of copper and graphite respectively. The effect of blending copper and graphite at different volume % to the prepared molding powder on the specific electrical resistance of the product was studied. It was concluded that the specific electrical resistance of molding powder was decreased from 2.1 x 1011 to 3.05 x 106 ohm. cm at 70% volume copper and from 2.3 x 104 to 2 x 102 ohm.cm at 80% volume graphite

194

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

195

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

196

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

197

All-Solid-State Conductive Polymer Miniaturized Reference Electrode  

Science.gov (United States)

A novel, stable, and all-solid-state miniaturized reference electrode (MRE) prepared by changing the properties of a conductive polymer for potentiometric applications is presented in this study. A monomer of a conductive polymer, pyrrole, was electrodeposited to form polypyrrole on an indium-tin oxide (ITO) glass at a DC power of 5 V. The difference of the solid-state MRE from the Ag/AgCl glass reference electrode is that the former requires no inner electrolyte and can be preserved without any storage solution (such as saturated KCl solution). In this study, the potentiometric characteristics of the solid-state MRE are investigated using the current-voltage (I-V) measurement system. The solid-state MRE exhibits sufficient stability and reproducibility in acid-base, sodium chloride, and potassium chloride solutions. Furthermore, the solid-state MRE can collocate successfully with H+-, Na+-, and K+-ion selective electrodes to measure H+, Na+, and K+ ion concentrations in acid-base, sodium chloride, and potassium chloride solutions, respectively.

Chen, Chien Cheng; Chou, Jung Chuan

2009-11-01

198

Conducting-polymer-based radar-absorbing materials  

Science.gov (United States)

The controllability of conductivity and the ease of manufacturing/coating of conducting polymers enable tailor- made dielectric loss components for radar absorbing materials (RAM). Different polypyrrole (PPy) based RAM, e.g. paint/rubber containing PPy powder and PPy coated structural phenolic foams with a gradient of impedance, have been examined. Reflection loss strongly depends on thickness and complex permittivity of the material. For a single layer material, the optimum values of the real part, (epsilon) ', and imaginary part, (epsilon) ", of the complex permittivity required to achieve a minimum reflectivity at a given sample thickness are found by theoretical calculations. The conductivity of the PPy powder is controlled to obtain RAM with lowest reflectivity according to the calculated optimum values of (epsilon) ' and (epsilon) ". A paint panel containing 2 wt% of the PPy powder with a thickness of 2.5 mm exhibits a reflectivity less than $minus 10 dB over 12 to 18 GHz. Blending and milling in the manufacturing process can destroy the original fibrous shape of PPy aggregates leading to low absorbing performances. PPy can be coated on rigid or flexible open cell foams to provide a lightweight broadband RAM. In particular, a coating technique on phenolic foams (12 - 15 mm thick) with a pore size of micrometer order has been developed to generate a gradient of conductivity across the foam thickness. The PPy coated foams are broadband RAM.

Truong, Vo-Van; Turner, Ben D.; Muscat, Richard F.; Russo, M. S.

1997-11-01

199

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2009-01-01

200

Color combination of conductive polymers for black electrochromism.  

Science.gov (United States)

Conducting polymers that absorb three primary colors, red, green, and blue (RGB), were introduced with a yellow electrochromic polymer (Y) for the preparation of black electrochromic devices. Red poly(3-hexylthiophene) (P3HT) and blue poly(3,4-ethylenedioxythiophene) (PEDOT) were coated on one side of the electrode as a cathodically coloring electrochromic (EC) layer, while green poly(aniline-N-butylsulfonate) (PANBS) and yellow EC poly{[1,3-bis(9',9'-dihexylfluoren-20-yl)azulenyl]-alt-[2",7"-(9",9"-dihexylfluorenyl]} (PDHFA) were coated on the opposite electrode to complete a complementary EC device. The yellow PDHFA layer effectively compensated for absorption below 450 nm and above the 600 nm region, which was lacking in the RGB electrode. The resultant RGBY ECD provided a black color near the CIE black with L*, a*, and b* values of 32, -1.1, and 3.7, respectively, covering a broad absorption in the visible range in the colored state. The state of the black EC device was maintained, even after the electricity was turned off for 200 h, showing stable memory effect. PMID:22148317

Shin, Haijin; Kim, Yuna; Bhuvana, Thiruvelu; Lee, Jiyea; Yang, Xu; Park, Cheolmin; Kim, Eunkyoung

2012-01-01

 
 
 
 
201

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

Science.gov (United States)

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

202

Encapsulation of novel fluorescent nanocrystals (quantum dots) with a nanocomposite polymer and their assessment by in-vitro and in-vivo studies  

Science.gov (United States)

Advance in nanotechnology has led to the development of novel fluorescent probes called quantum dots which are being exploited for potential new methods of early cancer detection spread and therapeutic management. Concerns regarding the release of potentially toxic inorganic core atoms into their surrounding environment and possession of hydrophobic surfaces are hindering the development of quantum dots. In order to abrogate their toxicity and solubilise the nanocrystals in aqueous solution a novel polyhedral oligomeric silsesquioxanes (POSS) poly(carbonate-urea)urethane (PCU), a silica nanocomposite (NC) polymer has been used to coat them. Physical and chemical analysis of the coated quantum dots with UV-Visible spectrometry, Photoluminescence, transmission electron microscopy, X-ray microanalysis and diffraction. Atomic force microscope and FTIR Spectrophotometry has enabled us ascertain the characteristics of these unique nanocrystals. The biocompatibility of the nanocomposite coated quantum dots (NCCQD) was assessed by using Alamar blue metabolic assay, Pico green assay and by measuring lactate dehydrogenase release on endothelial cell damage. Potential interference of NCCQD with a rat's normal physiology and systemic tissue distribution were assessed in an in-vivo animal model. Results demonstrated that the nanocrystals retained their unique optical properties, had a mean hydrodynamic diameter of 10.5 nm, excellent monodispersivity, large absorption spectrum with a narrow emission band at 790 nm and were highly photostable after polymer coating. NCCQD were compatible with endothelial cells as viable cells were demonstrated to be present after 14 days of growing cells in cell culture medium exposed to NCCQD at concentrations of 2.25 X 10"2 nM. There was no significant disturbance in the physiological parameters on injecting the NCCQD in an in-vivo rat model over a 2 hour period. NCCQD were seen to be deposited in the spleen and thymus as they are reticuloendothelial organs. In conclusion polymer encapsulated CdTe nanocrystals have tremendous potential to be exploited as a medical device in in-vivo imaging.

Iga, Arthur M.

203

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

204

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

Energy Technology Data Exchange (ETDEWEB)

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{sup -2}-2 S cm{sup -1} depending on the architecture of the coated layer. Further, the conductivity of the coated wood microfibers increased up to 20 S cm{sup -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{sup -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; Lvov, Yuri [Institute for Micromanufacturing, Louisiana Tech University, Ruston, LA 71272 (United States); Shim, Bong Sup; Kotov, Nicholas [Chemical Engineering Department, University of Michigan, Ann Arbor, MI 48109 (United States); Varahramyan, Kody [Electrical and Computer Engineering Department, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202 (United States)], E-mail: agarwal@iupui.edu

2009-05-27

205

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.

206

Spatioselective growth of metal-organic framework nanocrystals on compositionally anisotropic polymer particles.  

Science.gov (United States)

Selective growth of metal organic framework materials on the surface of compartmentalized polymer microparticles is achieved by electro-hydrodynamic co-jetting, selective surface modification, and anisotropic crystal growth. PMID:24677551

Park, Tae-Hong; Lee, Kyung Jin; Hwang, Sangyeul; Yoon, Jaewon; Woell, Christof; Lahann, Joerg

2014-05-01

207

Studies on Effect of Doping Alumina Nanoparticles in ION Conducting Polymer Nanocomposites.  

Directory of Open Access Journals (Sweden)

Full Text Available In this study the polymer composite specimen has been prepared by using polymer Polyvinyl- pyrrolidone (PVP a Potassium iodide (KI and alumina nanoparticles. The polymer composite specimens were developed by using solution cast techniques. The main objective of the project is to study microstructure, XRD, ionic conductivity, ionic transference number, glass transition temperature using DSC, microhardness and tensile properties of the polymer nanocomposite specimen. The results revealed conductivity as well as tensile strength increased of the polymer nanocomposite increased with concentration of alumina nanoparticles where as tensile strength reduced. The polymer electrolyte can be used in photovoltaic cell

Ritu Tomar

2013-09-01

208

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

209

Controlled synthesis of transition metal/conducting polymer nanocomposites  

Science.gov (United States)

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

Liu, Zhen; Liu, Yang; Zhang, Lin; Poyraz, Selcuk; Lu, Ning; Kim, Moon; Smith, James; Wang, Xiaolong; Yu, Yajiao; Zhang, Xinyu

2012-08-01

210

Controlled synthesis of transition metal/conducting polymer nanocomposites  

International Nuclear Information System (INIS)

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

211

Development of bioactive conducting polymers for neural interfaces.  

Science.gov (United States)

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

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

2010-01-01

212

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)

213

Soft capacitor fibers using conductive polymers for electronic textiles  

Science.gov (United States)

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.

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

2010-11-01

214

Conducting polymer composite materials for smart microwave windows  

Science.gov (United States)

Samples of poly(aniline)-silver-polymer electrolyte particulate composites have been characterized at microwave frequencies when small d.c. electric fields are applied across them in both coaxial line and waveguide measurement test sets. The experimental data shows that the initial conductivity of the materials is dependent on the concentration of sliver metal and suggest that changes in resistance due to chemical switching take place, at least in part, in the manufacture of the composites. When silver is used as the electrodes, the experimental data show that changes in the slope of the cyclic voltammograms coincide with large changes in microwave reflectivity or transmission consistent with increasing conductivity of the composites when fields are applied. The reverse change occurs when the fields are removed. Measurements have shown that the composites are able to switch between the two impedance stats in times of less than one second for well over a million cycles with no apparent depreciation in material properties. Large area films have also been prepared and studied using the 'free space' technique.

Barnes, Alan; Lees, K.; Wright, Peter V.; Chambers, Barry

1999-07-01

215

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-coglycolic 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-coglycolic acid).

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

1997-08-01

216

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

217

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

The synthesis and characterization of pyrazine-bridged polymers of iron(II/III), ruthenium(II/III), and osmium(II/III) octaethylporphyrin (dubbed “shish-kebab” polymers) are presented. Optical and dc conductivity measurements reveal that the ruthenium and osmium polymers, when partially oxidized, are highly conductive. Electrochemical and ESR results are presented that indicate the existence of an interesting metal-centered conduction pathway. Unlike most of the previously reported porphy...

Collman, James P.; Mcdevitt, John T.; Yee, Gordon T.; Leidner, Charles R.; Mccullough, Laughlin G.; Little, William A.; Torrance, Jerry B.

1986-01-01

218

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...

Drzal, Lawrence T.; Hiroyuki Fukushima; Kyriaki Kalaitzidou

2010-01-01

219

Electrically conducting polymers can noninvasively control the shape and growth of mammalian cells.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Electrically conducting polymers are novel in that their surface properties, including charge density and wettability, can be reversibly changed with an applied electrical potential. Such properties might render conducting polymers unique for biological applications. However, the majority of research on conducting polymers has been carried out under nonbiological conditions. We synthesized optically transparent polypyrrole thin films and studied them in environments suitable for protein adsor...

Wong, J. Y.; Langer, R.; Ingber, D. E.

1994-01-01

220

Mechanisms for current-induced conductivity changes in a conducting polymer  

Science.gov (United States)

A layer of polyethylene dioxythiophene:polystyrene sulfonic acid (PEDT:PSS) spun onto the surface of an inorganic semiconductor forms a highly asymmetric rectifying junction when a small current is applied and can be permanently open circuited with application of a high current density. This allows the polymer/semiconductor junction to function as a write-once-read-many-times memory element. We use x-ray photoelectron spectroscopy and temperature induced conductivity measurements to study the morphological and chemical changes responsible for the large current-induced conductivity changes. It is found that by applying a large current to the organic-inorganic semiconductor rectifying heterojunction structure Au /PEDT:PSS/Si, the ratio of PEDT+ to PSS- near the interface changes due to phase segregation in the presence of both high electric field (>105V/cm) and temperature. This leads to a decrease in film conductivity by up to six orders of magnitude from its value in the conductive state.

Xu, Xin; Register, Richard A.; Forrest, Stephen R.

2006-10-01

 
 
 
 
221

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.

222

A conducting polymer/ferritin anode for biofuel cell applications  

International Nuclear Information System (INIS)

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+ in the inner layer and the NAD+-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+ 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-2 in a 45 mM glucose solution and offers a good possibility for application in biofuel cells.

223

Transient radiation-induced electrical conductivity of polymers in mixed gamma and neutron fluxes  

International Nuclear Information System (INIS)

The transient radiation-induced electrical conductivity, excited by pulsed gamma and neutron fluxes in polymers in a vacuum at room temperature is in good qualitative agreement with analogous results observed during electron excitation of the investigated polymers. Quantitative differences in the transient radiation-induced electrical conductivities of the polymers can be explained by the presence of track effects during gamma and neutron irradiation

224

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

225

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

226

Doped conducting-polymer-semiconducting-polymer interfaces: Their use in organic photovoltaic devices  

Science.gov (United States)

We report a study of the interface between poly(p-phenylene vinylene) (PPV) and poly(ethylene dioxythiophene) doped with polystyrene sulfonic acid (PEDOT:PSS). We find from measurements of optical absorption and conductivity that PSS dopes PPV during the sample preparation. In addition, the photoluminescence efficiency of PPV is strongly affected by the presence of PSS which we attribute to the effect of chemical doping. We further studied the interaction between PSS and PPV by measurements of the photovoltaic response, spectrally resolved, of a number of diode structures. By forming the interface between a layer of PEDOT:PSS and a layer of PPV precursor prior to the thermal conversion we obtained an interpenetrating interface with large surface area between the photoresponsive and the charge collecting polymers. For devices made with PEDOT:PSS as top electrode and aluminum as the bottom electrode the short-circuit external quantum efficiency is 4%.

Arias, A. C.; Granström, M.; Thomas, D. S.; Petritsch, K.; Friend, R. H.

1999-07-01

227

Luminescent properties of polymer nanocomposites activated with praseodymium-doped nanocrystals  

Science.gov (United States)

In this work we report the recent results of our investigation on visible emission properties of the polymer nanocomposites doped with oxide and fluoride nanopowders activated with praseodymium ions. The set of LaAlO3 and YF3 nanopowders differing in active ions concentration, was carefully characterized with respect of their structural and luminescent properties. Also the PMMA-based nanocomposites doped with these nanopowders were manufactured and characterized. The measurements of excitation and emission spectra as well as fluorescence decays enabled comparison of emission properties of nano-composites and original nanopowders and discussion of the main excitation and deexcitation mechanisms, responsible for the optical properties of developed materials. This, in turn will enable optimization of developed manufacturing technology.

Jusza, A.; Lipinska, L.; Baran, M.; Mergo, P.; Millan, A.; Dieleman, F.; Piramidowicz, R.

2012-06-01

228

Towards p-type conductivity in SnO2 nanocrystals through Li doping  

International Nuclear Information System (INIS)

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

229

Towards p-type conductivity in SnO2 nanocrystals through Li doping.  

Science.gov (United States)

This paper examines electrical transport properties and Li doping in SnO(2) synthesized by the sol-gel method. Solid-state (7)Li-NMR lineshapes reveal that Li ions occupy two distinct sites with differing dynamic mobilities. The chemical exchange rate between the two sites is, however, too slow for detection on the NMR timescale. Compressed nanoparticulate films of this doped semiconductor exhibit a positive Seebeck coefficient implying a p-type conductivity. A variable-temperature direct current conductivity, over a 25-350 degrees C temperature range, follows an Efros-Shklovskii variable range hopping (ES-VRH) conduction mechanism (ln(rho) versus T(-1/2)) at temperatures below 100 degrees C with a crossover to 2D Mott variable range hopping (M-VRH) (ln(rho) versus T(-1/3)) conduction at temperatures above 250 degrees C. In a transition region between these two limiting behaviors, the dc resistivity exhibits an anomalous temperature-independent plateau. We suggest that its origin may lie in a carrier inversion phenomenon wherein the majority carriers switch from holes to electrons due to Li ion expulsion from the crystalline core and creation of oxygen vacancies generated by loss of oxygen at elevated temperatures. PMID:19966386

Chaparadza, Allen; Rananavare, Shankar B

2010-01-22

230

Assembly of antimony doped tin oxide nanocrystals into conducting macroscopic aerogel monoliths.  

Science.gov (United States)

We present the assembly of preformed antimony doped tin oxide nanobuilding blocks into centimeter sized aerogels with surface areas exceeding 340 m(2) g(-1). After calcination, the resistivity of the aerogels was decreased by 4 orders of magnitude to a few k? cm, with the primary conducting structures measuring only a few nanometers. PMID:25229075

Rechberger, Felix; Ilari, Gabriele; Niederberger, Markus

2014-11-01

231

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

232

Studies on Proton Conducting Polymer Electrolytes Based on Pvdf-Pva with NH4NO3  

Science.gov (United States)

PVDF-PVA polymer electrolytes with various blend ratios are prepared by solution casting technique with DMF (Merck) as solvent to optimize the blend ratio on the basis of high ionic conductivity. Then, different concentrations of NH4NO3 are doped with the optimized PVDF-PVA blend ratio and polymer blend electrolytes are prepared. The complex formation has been confirmed by XRD and FTIR analysis. The ac impedance studies are performed to evaluate the ionic conductivity of the polymer electrolyte membranes in the range 303-323K and it is found that the temperature dependence of ionic conductivity of the polymer blend electrolytes obey the Arrhenius relation. The maximum ionic conductivity is found to be 5.99×10-4 S/cm with activation energy Ea=0.21 eV for PVDF-PVA-NH4NO3 (80:20:0.4MWt%) polymer electrolyte.

Muthuvinayagam, M.; Gopinathan, C.; Rajeswari, N.; Selvasekarapandian, S.; Sanjeeviraja, C.

2013-07-01

233

Epitaxy-assisted creation of PCBM nanocrystals and its application in constructing optimized morphology for bulk-heterojunction polymer solar cells.  

Science.gov (United States)

PCBM (a C60 derivative) is so far the most successful electron acceptor for bulk-heterojunction polymer photovoltaic (PV) cells. Here we present a novel method epitaxy-assisted creation of PCBM nanocrystals and their homogeneous distribution in the matrix using freshly cleaved mica sheet as the substrate. The highly matched epitaxy relationship between the unit cell of PCBM crystal and crystallographic (001) surface of mica induces abundant PCBM nuclei, which subsequently develop into nanoscale crystals with homogeneous dispersion in the composite film. Both the shape and size of these nanocrystals could be tuned via choosing the type of matrix polymer, film thickness, ratio of PCBM in the composite film, and annealing temperature. Thus, the obtained thin composite film is removed from the original mica substrate via the flotation technique and transferred to a real substrate for device completion. The success of this method has been verified by the substantially improved device performance, in particular the increased short-circuit current, which is heavily dependent on the morphology of the photoactive layer. Therefore, we have actually demonstrated a novel approach to construct preferred morphology for high-performance optoelectronic devices via resorting to other specific substrates which could induce the formation of this type morphology. PMID:19367916

Li, Ligui; Lu, Guanghao; Li, Sijun; Tang, Haowei; Yang, Xiaoniu

2008-12-11

234

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

Science.gov (United States)

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 4 and 10 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.; Lascola, Robert J.; Clark, Elliot A.

2010-12-01

235

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

236

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

International Nuclear Information System (INIS)

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 104 and 105 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 ardical formation and chain cross-linking are most likely the two dominant mechanisms for conductivity change and not de-protonation of the polymer.

237

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

238

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 Conjug...

S Srilalitha, K. N. Jayaveera

2013-01-01

239

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

240

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

 
 
 
 
241

FINAL REPORT. SENSORS USING MOLECULAR RECOGNITION IN LUMINESCENT, CONDUCTIVE POLYMERS  

Science.gov (United States)

The purpose of this project is to develop sensor technology for detecting specific heavy metal ions, such as transition metals, lead, lanthanides, and actinides in waste streams. The sensing strategy uses molecular recognition of the metal ions by polymers that change their lumin...

242

Reversible post-breakdown conduction in aluminum oxide-polymer capacitors  

Science.gov (United States)

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

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

2013-04-01

243

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

Science.gov (United States)

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

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

1999-12-01

244

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

245

Protecting conductive polymer wire from oxidation using an air-impermeable polyisobutylene coating  

International Nuclear Information System (INIS)

The decay of the electrical conductivity over time under environmental conditions sets restrictions to some possible technical applications of polymer electronics. We report here that a polyisobutylene (PI) coating can act as a protecting layer that prevents the oxidation of polyaniline by oxygen and thereby increase the lifetime of polymer electronics

246

Protecting conductive polymer wire from oxidation using an air-impermeable polyisobutylene coating  

Energy Technology Data Exchange (ETDEWEB)

The decay of the electrical conductivity over time under environmental conditions sets restrictions to some possible technical applications of polymer electronics. We report here that a polyisobutylene (PI) coating can act as a protecting layer that prevents the oxidation of polyaniline by oxygen and thereby increase the lifetime of polymer electronics.

Ji Haifeng [Institute for Micromanufacturing, Louisiana Tech University, Ruston, LA, 71272 (United States)]. E-mail: hji@chem.latech.edu; Shaik, Ziaul Haque [Institute for Micromanufacturing, Louisiana Tech University, Ruston, LA, 71272 (United States)

2005-09-22

247

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

248

Polymer monolithic capillary column fabricated by using monodisperse iron oxide nanocrystal template to enhance the electrochromatographic separation of small molecules.  

Science.gov (United States)

Monodisperse iron oxide nanocrystals and organic solvents were utilized as coporogens in monolithic poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) capillary columns to afford stationary phases with enhanced electrochromatographic performance of small molecules. While the conventional monoliths using organic solvents only as a porogen exhibited poor resolution (Rs) 3.0) and high efficiency ranged from 60?000 to 100?000 plates/m at the same linear velocity of 0.856 mm/s. It was considered that the mesopores introduced by the nanocrystals played an important role in the improvement of the monolith performance. This new strategy expanded the application range of the hydrophobic monoliths in the separation of polar alkaloids and narcotics. The successful applications demonstrated that the glycidyl methacrylate based monoliths prepared by using nanocrystal template are a good alternative for enhanced separation efficiency of small molecules. PMID:24648248

Lin, Zian; Wang, Juan; Yin, Xiaofei; Tan, Xiaoqing; Yu, Ruifang; Zheng, Jiangnan; Zhang, Lan; Chen, Guonan

2014-07-01

249

Effect of Dimethyl Carbonate Plasticizer on Ionic Conductivity of Methyl Cellulose-Based Polymer Electrolytes  

International Nuclear Information System (INIS)

Influences of dimethyl carbonate (DMC) plasticizer on ionic conductivity, dielectric permittivity and electrical modulus formalism of methyl cellulose (MC)-based polymer electrolytes have been studied. The room temperature electrical conductivity as measured by impedance spectroscopy shows that a methyl cellulose film has a conductivity of ?10-10 S cm-1. In this study, other than KOH ionic dopant, DMC plasticizer is also added to the polymer with the aim of enhancing the electrical conductivity of the polymer. The highest room temperature conductivity of the plasticised sample is ?10-5 S cm-1. The plot of log ? versus 103/ T for the highest conducting sample obeys Arrhenius rule indicating that the conductivity occurs by thermally activated mechanism. (author)

250

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

251

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

252

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)

253

Electric conductivity of siliconorganic polyhomoconjugated polymer films upon adsorption of volatile organic compounds  

Science.gov (United States)

The electrophysical parameters of polyhomoconjugated organosilicon polymer films are studied, and variation of their conductivity under the action of water, toluene, and ammonia vapors is measured. Films 1-2 ?m thick are prepared by the casting method from a solution of poly[2,2-dimethyl-2-sila-1,3-propylene-(4, 4'-biphenylene)]a (polymer I) and poly[2- n -butyl-2-phenyl-2-sila-1,3-propylene-(4, 4'-biphenylene)]a (polymer II). In the course of conductivity measurement, organic volatiles and water are adsorbed due to a stepwise rise in the pressure over the sample from 10-3 to 10-1 Torr. The initial values of the resistivity of polymers I and II are estimated as 4 × 109 ? cm. Exposure of the films to organic volatile vapors and water vapor causes a reversible change in the conductivity of the films. For polymer-I films, the conductivity upon adsorption of ammonia, toluene, and water vapors exceeds the initial value by 150, 10, and 600 times, respectively. The sensitivity of polymer-II films is lower by a factor of 1.5-2.0. The time of conductivity variation as the vapors are injected and evacuated is within 10 and 30 s, respectively. The mechanisms of organic volatile and water adsorption on the surface of polyhomoconjugated organosilicon polymer films are compared with adsorption mechanisms on the surface of ?-polyconjugated organic films.

Komolov, A. S.; Gerasimova, N. B.; Lazneva, E. F.; Gusarov, A. A.; Osadchev, A. Yu.; Shamanin, V. V.

2009-02-01

254

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

2014-07-21

255

Towards fully optimized conducting polymer bending sensors: the effect of geometry  

International Nuclear Information System (INIS)

Conducting polymer devices have been demonstrated to generate a current or voltage in response to a displacement or force, which facilitates their use as mechanical sensors. Trilayer bending sensors are laminated conducting polymer devices that can provide self-contained operation in air, while maintaining many of the desirable conducting polymer properties including low weight and biocompatibility. This paper extends our previous characterization work by identifying the frequency response of the sensor output as the device geometry is varied and at frequencies up to 300 Hz. Current output is found to increase with the volume of conducting polymer across the sensor spectrum, while the usable sensor bandwidth is bounded by low-pass behaviour and a peak at the low frequency end of the spectrum and by a mechanical resonance at high frequencies. On the basis of these findings, suggestions are presented which can be used to optimize the current output and bandwidth of trilayer bender sensors

256

Nonlinear transmission properties of nanostructures with single-wall carbon nanotubes and conductive polymers  

Science.gov (United States)

Using the concept of self-assembly, we formed orderly structured nanocomposites based on single-wall carbon nanotubes, which were electrochemically wrapped with conductive polymers. We report on the nonlinear optical transmission characteristics of such materials.

Han, H.; Chen, J.; Diamant, Y.; Etienne, M.; Walser, A.; Dorsinville, R.; Grebel, H.

2005-01-01

257

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

Science.gov (United States)

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

258

Towards fully optimized conducting polymer bending sensors: the effect of geometry  

Science.gov (United States)

Conducting polymer devices have been demonstrated to generate a current or voltage in response to a displacement or force, which facilitates their use as mechanical sensors. Trilayer bending sensors are laminated conducting polymer devices that can provide self-contained operation in air, while maintaining many of the desirable conducting polymer properties including low weight and biocompatibility. This paper extends our previous characterization work by identifying the frequency response of the sensor output as the device geometry is varied and at frequencies up to 300 Hz. Current output is found to increase with the volume of conducting polymer across the sensor spectrum, while the usable sensor bandwidth is bounded by low-pass behaviour and a peak at the low frequency end of the spectrum and by a mechanical resonance at high frequencies. On the basis of these findings, suggestions are presented which can be used to optimize the current output and bandwidth of trilayer bender sensors.

John, S. W.; Alici, G.; Spinks, G. M.; Madden, J. D.; Wallace, G. G.

2009-08-01

259

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

260

Redox active polymers with phenothiazine moieties for nanoscale patterning via conductive scanning force microscopy  

Science.gov (United States)

Redox active polymers with phenothiazine moieties have been synthesized by Atomic Transfer Radical Polymerization (ATRP). These novel polymers reveal bistable behaviour upon application of a bias potential above the oxidation threshold value. Using conductive Scanning Force Microscopy, two distinguishable conductivity levels were induced on a nanoscale level. These levels were related to a high conducting ``On'' and a low conducting ``Off'' state. The ``On'' state is generated by the oxidation of the phenothiazine side chains to form stable phenothiazine radical cations. The formation and stability of the radical sites was examined by cyclic voltammetry, electron spin resonance and optical spectroscopy. Polymers with phenothiazine moieties show the ability to retain their redox state for several hours and can therefore be used for nonvolatile organic memory devices. Furthermore, thin films made from the phenothiazine containing polymers show high mechanical nanowear stability.Redox active polymers with phenothiazine moieties have been synthesized by Atomic Transfer Radical Polymerization (ATRP). These novel polymers reveal bistable behaviour upon application of a bias potential above the oxidation threshold value. Using conductive Scanning Force Microscopy, two distinguishable conductivity levels were induced on a nanoscale level. These levels were related to a high conducting ``On'' and a low conducting ``Off'' state. The ``On'' state is generated by the oxidation of the phenothiazine side chains to form stable phenothiazine radical cations. The formation and stability of the radical sites was examined by cyclic voltammetry, electron spin resonance and optical spectroscopy. Polymers with phenothiazine moieties show the ability to retain their redox state for several hours and can therefore be used for nonvolatile organic memory devices. Furthermore, thin films made from the phenothiazine containing polymers show high mechanical nanowear stability. Electronic supplementary information (ESI) available: Fig. S1-S8. See DOI: 10.1039/c1nr10917k

Golriz, Ali A.; Kaule, Tassilo; Heller, Jeannine; Untch, Maria B.; Schattling, Philipp; Theato, Patrick; Toda, Masaya; Yoshida, Shinya; Ono, Takahito; Butt, Hans-Jürgen; Gutmann, Jochen Stefan; Berger, Rüdiger

2011-12-01

 
 
 
 
261

Ionic conductivity of polymer gels deriving from alkali metal ionic liquids and negatively charged polyelectrolytes  

International Nuclear Information System (INIS)

We have prepared polymer gel electrolytes with alkali metal ionic liquids (AMILs) that inherently contain alkali metal ions. The AMIL consisted of sulfate anion, imidazolium cation, and alkali metal cation. AMILs were mixed directly with poly(3-sulfopropyl acrylate) lithium salt or poly(2-acrylamido-2-methylpropanesulfonic acid) lithium salt to form polymer gels. The ionic conductivity of these gels decreased with increasing polymer fraction, as in general ionic liquid/polymer mixed systems. At low polymer concentrations, these gels displayed excellent ionic conductivity of 10-4 to 10-3 S cm-1 at room temperature. Gelation was found to cause little change in the 7Li diffusion coefficient of the ionic liquid, as measured by pulse-field-gradient NMR. These data strongly suggest that the lithium cation migrates in successive pathways provided by the ionic liquids

262

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

263

A precursor approach to the synthesis and fabrication of conducting polymers  

Science.gov (United States)

Poly(terthiophene) nanostructures consisting of periodic nanolines were prepared using the precursor polymer approach in conjunction with nanoimprint lithography. Precursor poly(norbornylene)s consisting of terthiophene side chains were prepared from their corresponding norbornylene monomers via ring opening metathesis polymerization. A copolymer consisting of terthiophene norbornylene and acetate norbornylene repeat units with a 50:50 composition exhibited a glass transition temperature of 52°C. Nanolines of percursor polynorbornylene were prepared by thermal nanoimprint lithography. The nanoimprinted precursor polymer was then converted to conjugated conductive polymer via chemical and electrochemical oxidation of the terthiophene side units. Nanoimprinted lines of conductive poly(terthiophene) exhibited high electrochromic contrast at 437 nm. Poly(arylenesilylene)s showed the promising aspects as a precursor polymer to form conducting polymers via oxidative electrochemical or chemical desilylation. Poly(arylenesilylene)s can be prepared in one pot reaction and their physical properties can be tuned by introducing different silane derivatives. Poly[(2,2'-bithienylene)dimethylsilylene] was prepared by coupling reaction between dilithiated 2,2'-bithiophene and dichlorodimethylsilane. Conversion of the precursor polymer to poly(bithiophene) was carried out via solid state electrochemical oxidation and confirmed by optical and electrochemical analyses. As a demonstration, poly[(2,2'-bithienylene)dimethylsilylene] was melt drawn into a fiber and converted to the poly(bithiophene) via solid state oxidative electrochemical conversion. Solution processable poly(arylenesilylene)s were prepared by introducing silanes having longer alkyl groups than methyl groups. Nanofibers of precursor polymers were obtained from precursor polymer solutions via electrospinning. The formation of poly(bithiophene) fibers via the solid-state oxidative conversion of electrospun precursor poly(bithienylenesilylene) nanofibers was confirmed electrochemically. The conductive polymer nanofiber mat obtained from the precursor polymer showed the similar electrochromic functionality to that of poly(bithiophene).

Choi, Jia

264

Electrochemistry of conductive polymers 39. Contacts between conducting polymers and noble metal nanoparticles studied by current-sensing atomic force microscopy.  

Science.gov (United States)

Electrical properties of contacts formed between conducting polymers and noble metal nanoparticles have been examined using current-sensing atomic force microscopy (CS-AFM). Contacts formed between electrochemically prepared pi-conjugated polymer films such as polypyrrole (PPy), poly(3-methylthiophene) (P3MeT), as well as poly(3,4-ethylenedioxythiophene) (PEDOT) and noble metal nanoparticles including platinum (Pt), gold (Au), and silver (Ag) have been examined. The Pt nanoparticles were electrochemically deposited on a pre-coated PPy film surface by reducing a platinum precursor (PtCl62-) at a constant potential. Both current and scanning electron microscopic images of the film showed the presence of Pt islands. The Au and Ag nanoparticles were dispersed on the P3MeT and PEDOT film surfaces simply by dipping the polymer films into colloid solutions containing Au or Ag particles for specified periods (5 to approximately 10 min). The deposition of Au or Ag particles resulted from either their physical adsorption or chemical bonding between particles and the polymer surface depending on the polymer. When compared with PPy, P3MeT and PEDOT showed a stronger binding to Au or Ag nanoparticles when dipped in their colloidal solutions for the same period. This indicates that Au and Ag particles are predominantly linked with the sulfur atoms via chemical bonding. Of the two, PEDOT was more conductive at the sites where the particles are connected to the polymer. It appears that PEDOT has better aligned sulfur atoms on the surface and is strongly bonded to Au and Ag nanoparticles due to their strong affinity to gold and silver. The current-voltage curves obtained at the metal islands demonstrate that the contacts between these metal islands and polymers are ohmic. PMID:17181203

Cho, Shin Hyo; Park, Su-Moon

2006-12-28

265

Electrochemical synthesis and characterization of a new conducting polymer: Polyrhodanine  

Science.gov (United States)

An antimicrobial drug, rhodanine (Rh), was electrochemically polymerized on a Pt electrode using cyclic voltammetry (CV). The high quality and homogeneous polyrhodanine (pRh) films with a dark-purple color were obtained. The chemical structure characterization was investigated by Fourier transform infrared spectroscopy (FTIR) and UV-vis spectroscopy techniques. Further, thermogravimetric analysis (TGA) and differential thermal analysis (DTA) techniques used to investigate thermal properties of the film. It is found that thermal stability of pRh films is relatively high. It is also observed that tetrahydrofurane (THF) and N-methyl-2-pyrrolidone (NMP) are good solvents for the polymer.

Karda?, Gülfeza; Solmaz, Ramazan

2007-01-01

266

The removal of precious metals by conductive polymer filtration  

Energy Technology Data Exchange (ETDEWEB)

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

Cournoyer, M.E.

1996-10-01

267

Distinctive Magneto Conductance and Universal Scaling in One Dimensional Polymer Nanofibers  

Science.gov (United States)

The conducting polymers are one dimensional organic hydrocarbon systems where the non-linear local excitations such as solitons, polarons and bipolarons were predicted based on the electron-phonon interactions. The local excitations have different spin-charge relations in different kinds of polymers. In this work, the magneto conductance (MC) of polymer nanofibers is investigated in high magnetic field at low temperature to understand both spin (magneto) and charge (conductance) of the charge carriers simultaneously. We discovered the distinctive zero MC in polyacetylene nanofibers while the finite MC in polyaniline and polythiophene nanofibers. On the other hand, the charge transports of polymer nanofibers as a function of temperature and bias are observed to be scaled onto the universal curve. We conclude that the universal scaling and the zero MC (the finite MC) in polyacetylene (polyaniline and polythiophene) nanofibers are from the interacting spinless charged solitons (interacting polarons which have both spin and charge).

Choi, Ajeong; Kim, Kyung Ho; Hong, Sung Ju; Goh, Munju; Akagi, Kazuo; Kaner, Richard B.; Park, Yung Woo

2012-02-01

268

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

269

Characteristics and Mechanisms in Ion-Conducting Polymer Films as Chemical Sensors  

Energy Technology Data Exchange (ETDEWEB)

Solid Polymer Electrolytes (SPE) are widely used in batteries and fuel cells because of the high ionic conductivity that can be achieved at room temperature. The ions are usually Li or protons, although other ions can be shown to conduct in these polymer films. There has been very little published work on SPE films used as chemical sensors. The authors have found that thin films of polymers like polyethylene oxide (PEO) are very sensitive to low concentrations of volatile organic compounds (VOCs) such as common solvents. Evidence of a new sensing mechanism involving the percolation of ions through narrow channels of amorphous polymer is presented. They present impedance spectroscopy of PEO films in the frequency range 0.0001 Hz to 1 MHz for different concentrations of VOCs and relative humidity. They find that the measurement frequency is important for distinguishing ionic conductivity from the double layer capacitance and the parasitic capacitance.

HUGHES,ROBERT C.; YELTON,WILLIAM G.; PFEIFER,KENT B.; PATEL,SANJAY V.

2000-07-12

270

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.

271

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2010-09-15

272

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

Energy Technology Data Exchange (ETDEWEB)

Highlights: {yields} PVAc/PVdF-co-HFP based polymer blend electrolyte for various concentration of LiClO{sub 4} were prepared and characterized. {yields} It is found that all the prepared electrolyte systems exhibited a maximum ionic conductivity of the order of x10{sup -4} Scm{sup -1}. {yields} Surface morphology of the polymer electrolyte membrane sample having maximum ionic conductivity is studied by atomic force microscopy. {yields} 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{sup -4} Scm{sup -1} at 303 K for PVAc:PVdF-co-HFP ((25/75) wt%):LiClO{sub 4} (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.

Ulaganathan, M., E-mail: nathanphysics@gmail.com [School of Physics, Alagappa University, Karaikudi, Tamil Nadu 630003 (India); ZECA Power Pte Ltd, 16D Enterprise Road Enterprise 10, Singapore 627653 (Singapore); Pethaiah, S. Sundar [Gashub Technology Pte Ltd, No. 17 Wodlands Terrace, Woodlands East Industrial Estate, Singapore 738442 (Singapore); Rajendran, S., E-mail: sraj54@yahoo.com [School of Physics, Alagappa University, Karaikudi, Tamil Nadu 630003 (India)

2011-09-15

273

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.ts are detailed in this paper.

274

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

275

Intrinsically conducting polymers and copolymers containing triazole moieties  

Energy Technology Data Exchange (ETDEWEB)

Random copolymer and terpolymers of 1,2,3-triazole-containing acrylates and poly(ethylene glycol)methyl ether acrylate (PEGMEA) have been synthesized and characterized. Proton conductivity measurements were made using impedance spectroscopy. The range of conductivity values from 80 C to 200 C spans only 1.5 orders of magnitude, demonstrating reduced temperature dependence over previously reported heterocycle based anhydrous proton conducting membranes. Introduction of PEG graft chains increased conductivity on both an absolute and T-T{sub g} normalized scale up to 30 mol% PEGMEA. Further increases in conductivity were achieved through addition of trifluoroacetic acid where increases of 0.5 to 1.5 orders of magnitude were observed depending on doping level. (author)

Martwiset, Surangkhana; Woudenberg, Richard C.; Granados-Focil, Sergio; Coughlin, E. Bryan [Department of Polymer Science and Engineering, University of Massachusetts Amherst, 120 Governors Drive, Amherst, MA 01003 (United States); Yavuzcetin, Ozgur; Tuominen, Mark T. [Department of Physics, University of Massachusetts Amherst, 411 Hasbrouck Laboratory, Amherst, MA 01003 (United States)

2007-08-15

276

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

277

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

278

A study on nanocomposites made of a conducting polymer and metallic nanoparticles  

Energy Technology Data Exchange (ETDEWEB)

Conducting polymers offer a unique combination of properties that makes them attractive materials for many electronic applications. PEDOT:PSS is one of the most successful conductive materials which is considered to be highly stable and resisting degradation under typical ambient conditions. In this study, we have prepared two sets of conducting polymer nano-composites. The first set is composed of PEDOT:PSS doped with different aspect ratios of gold nanorod and the other one is PEDOT:PSS doped with different sizes of gold nanosphere. The chemical reduction method was used for preparing the nano-particles. Indeed, gold nanorods and nanosphere which exhibit tunable absorption as a function of their size and aspect ratio, respectively, have tuned the absorption coefficient for PEDOT: PSS. The nature of the dopant as well as the degree of doping has played a significant role in the improvement of the electrical conductivity of conducting polymer.

Mohammed Ahmed Khalil, Rania [Nanochemistry and Nanoengineering, Institute for Materials Science, Faculty of Engineering, Christian-Albrechts-University of Kiel (Germany); Multicomponent Materials, Institute for Materials Science, Faculty of Engineering, Christian-Albrechts-University of Kiel (Germany); Abdelaziz Mahmoud Abdelaziz, Ramzy [Nanochemistry and Nanoengineering, Institute for Materials Science, Faculty of Engineering, Christian-Albrechts-University of Kiel (Germany); Strunkus, Thomas; Faupel, Franz [Multicomponent Materials, Institute for Materials Science, Faculty of Engineering, Christian-Albrechts-University of Kiel (Germany); Elbahri, Mady [Nanochemistry and Nanoengineering, Institute for Materials Science, Faculty of Engineering, Christian-Albrechts-University of Kiel (Germany); Helmholtz-Zentrum Geesthacht GmbH, Institute of Polymer Research, Nanochemistry and Nanoengineering (Germany)

2011-07-01

279

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

280

Field effect type devices based on highly doped conducting polymer  

Science.gov (United States)

Field-effect type devices based on the highly doped polymer poly(3,4-ethylenedioxythiophene)/polystyrene sulfonic acid (PEDOT/PSS) show a reversible change of the source-drain current by several orders of magnitude upon application of appropriate gate voltages. However, the underlying physical mechanism of their operation is little understood so far. A field-effect like operation, dopant ion diffusion, or electrochemical process has been conjectured. In this work, we investigated devices fabricated on glass substrates with polyvinyl phenol and aluminum as dielectric layer and gate, respectively. We applied a saw tooth shaped voltage profile to the gate electrode and a very small source-drain voltage while measuring gate and source-drain currents. These measurements resemble capacitance-voltage measurements used to study the field-effect in inorganic devices as well as cyclic voltammetry used in electrochemical work. Conclusions concerning the operation principle will be discussed. Supported in part by ONR.

Waldmann, O.; Park, J. H.; Hsu, F. C.; Chiou, N. R.; Kim, Y. R.; Epstein, A. J.

2003-03-01

 
 
 
 
281

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

282

Effect of Applied Potential on the Electrochemical Deposition of Styrene-Butadiene Co-Polymer Based Conducting Polymer Composite  

Science.gov (United States)

Homogeneous conducting polymer composite films with improved electrical properties are synthesized via electrochemical polymerization of polyaniline on Styrene butadiene rubber coated steel electrode. The electrochemical polymerization is carried out by potentiostatic method using an aqueous solution of 0.2 M aniline and 1.5 M sulphuric acid as electrolyte in a single compartment electrochemical cell. The optical studies show successful incorporation of polyaniline into the matrix polymer film. The effect of applied potential on the electrodeposition of composite is studied by cyclic voltammetry and by impedance spectroscopic measurements.

Mathew, Anisha Mary; Neena, P.

2011-10-01

283

Fabrication of flexible polymer dispersed liquid crystal films using conducting polymer thin films as the driving electrodes  

International Nuclear Information System (INIS)

Conducting polymers exhibit good mechanical and interfacial compatibility with plastic substrates. We prepared an optimized coating formulation based on poly(3,4-ethylenedioxythiophene) (PEDOT) and 3-(trimethoxysilyl)propyl acrylate and fabricated a transparent electrode on poly(ethylene terephthalate) (PET) substrate. The surface resistances and transmittance of the prepared thin films were 500-600 ?/? and 87% at 500 nm, respectively. To evaluate the performance of the conducting polymer electrode, we fabricated a five-layer flexible polymer-dispersed liquid crystal (PDLC) device as a PET-PEDOT-PDLC-PEDOT-PET flexible film. The prepared PDLC device exhibited a low driving voltage (15 VAC), high contrast ratio (60:1), and high transmittance in the ON state (60%), characteristics that are comparable with those of conventional PDLC film based on indium tin oxide electrodes. The fabrication of conducting polymer thin films as the driving electrodes in this study showed that such films can be used as a substitute for an indium tin oxide electrode, which further enhances the flexibility of PDLC film

284

Fabrication of flexible polymer dispersed liquid crystal films using conducting polymer thin films as the driving electrodes  

Energy Technology Data Exchange (ETDEWEB)

Conducting polymers exhibit good mechanical and interfacial compatibility with plastic substrates. We prepared an optimized coating formulation based on poly(3,4-ethylenedioxythiophene) (PEDOT) and 3-(trimethoxysilyl)propyl acrylate and fabricated a transparent electrode on poly(ethylene terephthalate) (PET) substrate. The surface resistances and transmittance of the prepared thin films were 500-600 {omega}/{open_square} and 87% at 500 nm, respectively. To evaluate the performance of the conducting polymer electrode, we fabricated a five-layer flexible polymer-dispersed liquid crystal (PDLC) device as a PET-PEDOT-PDLC-PEDOT-PET flexible film. The prepared PDLC device exhibited a low driving voltage (15 VAC), high contrast ratio (60:1), and high transmittance in the ON state (60%), characteristics that are comparable with those of conventional PDLC film based on indium tin oxide electrodes. The fabrication of conducting polymer thin films as the driving electrodes in this study showed that such films can be used as a substitute for an indium tin oxide electrode, which further enhances the flexibility of PDLC film.

Kim, Yang-Bae [Institute of Photonics and Surface Treatment, Q-SYS Co. Ltd., 971-14, Wolchul-dong, Buk-gu, Gwangju 500-460 (Korea, Republic of); Park, Sucheol [Department of Polymer Science and Engineering, Chosun University, 375, Susuk-dong, Dong-gu, Gwangju 501-759 (Korea, Republic of); Hong, Jin-Who [Department of Polymer Science and Engineering, Chosun University, 375, Susuk-dong, Dong-gu, Gwangju 501-759 (Korea, Republic of)], E-mail: jhhong@chosun.ac.kr

2009-03-31

285

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

286

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

287

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

International Nuclear Information System (INIS)

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

288

Nanocrystal quantum dots  

CERN Document Server

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

Klimov, Victor I

2010-01-01

289

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

International Nuclear Information System (INIS)

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.

290

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

291

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

Energy Technology Data Exchange (ETDEWEB)

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 {pi} 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 {pi}-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.

Mohan, Swati [School of Materials Science and Technology, Institute of Technology, Banaras Hindu University, Varanasi 221005 (India); Prakash, Rajiv, E-mail: rajivprakash12@yahoo.com [School of Materials Science and Technology, Institute of Technology, Banaras Hindu University, Varanasi 221005 (India)

2010-06-15

292

Interface-driven conductance transition in nanostructured polymer networks  

Science.gov (United States)

We report an anomalous electronic transport signature in polyaniline nanofiber networks probed via the temperature-dependent dc conductivity [?dc(T)] , reflectance [R(?,T)] over a broad frequency range (300-50000cm-1) , and x-ray diffraction. We determined that disorder and localization dominate the bulk charge dynamics and propose that the origin of the atypical electronic transport signature in the nanofibers networks is the “fragile” nature of the conductance at the nanofiber interfaces resulting from the strong T -dependent localization of electronic states in the nanostructure interface regions.

Adetunji, O. O.; Chiou, N.-R.; Epstein, A. J.

2009-07-01

293

The electrical conductivity of a network polymer based on tetraphenylcalix[4]resorcinarene  

Science.gov (United States)

The electrical conductivity of a polymer based on tetraphenylcalix[4]resorcinarene in the form of H+, Na+, Li+, Ag+, and Ba2+ cations was measured, and the self-diffusion coefficients and activation energies of metal cation diffusion in the polymer phase were calculated. It was found that the specific conductivity of the polymer in the form of Ba2+ cations was 0.004 S/cm, increased to 0.01 S/cm when the polymer was in the form of singly-charged metal cations, and became as high as 0.2 S/cm when the polymer was transformed into the H form. It was shown that the self-diffusion coefficients of metal cations in the polymer phase increased in the sequence Ba2+ Li+ < Na+. The conclusion was made that, over the temperature range 298-333 K, the activation energy of metal cation diffusion in polymer was 14-15 kJ/mol and did not obviously depend on the cation charge.

Al'Tshuler, G. N.; Ostapova, E. V.

2009-06-01

294

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1993-03-15

295

Application for continuation of mixed ionic and electronic conductivity in polymers  

Energy Technology Data Exchange (ETDEWEB)

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

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

1990-01-01

296

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...

Matencio Tulio; Pernaut Jean Michel; Vieil Eric

2003-01-01

297

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

298

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

299

Current state and future directions of research and development in conducting polymers  

International Nuclear Information System (INIS)

Polymers that inherently conduct electricity have been researched intensively for a little over 20 years. An enormous research effort in academic and industrial institutions has resulted in over 17,000 publications published in the last 10 years alone. Significant advances in the synthesis of new polymers and the methods for processing these polymers into products have resulted from this research activity. A number of commercial developments have emerged, some of which have reached maturity as marketed products. Some others have failed in the marketplace. The diversity of applications for conducting polymers continues to fuel research and development and ensures that new products will emerge over the foreseeable future. In the more distant future, truly intelligent polymer systems remain as an achievable objective. By developing appropriate processing and fabrication technologies, it should be possible to integrate sensing, actuating and energy storage functions into a single system. Further developments in self-assembly of conducting polymers from the nano- to the meso-scale will open up applications in MEMS and nanotechnology

300

Design and Fabrication of Molecular Assemblies of Conductive Polymers  

Science.gov (United States)

Two new methods of fabricating multilayer Langmuir -Blodgett (LB) thin films of electrically conductive polyaniline and a novel method of constructing molecular assemblies of polyaniline via the spontaneous adsorption (SA) technique were developed. Quantitative transmission/reflection Fourier transform infrared spectroscopy, polarized ultraviolet -visible spectroscopy and X-ray diffraction techniques were used to examine the structure and composition of multilayer thin films. In the structural study of LB films fabricated from 3-octadecyl pyrrole (3-ODP), 3-octadecanoyl pyrrole (3-ODOP) and polypyrrole/3-ODOP (PPY/3-ODOP), the level of order and orientation were found to be affected by the intermolecular and intramolecular interactions between molecules. For the manipulation of polyaniline using the LB technique, stable and easily transferrable LB monolayers were formed at the air-water interface by mixing polyaniline in its emeraldine-base form (PANb) with two processing aids. Films fabricated from the PANb/StA mixture were found to be phase separated with domains of polyaniline and stearic acid while those from the PANb/PI blend were found to be miscible. Both polyaniline LB films were rendered conductive by doping with 1 M HCl or HCl vapor. Multilayer polyaniline films were also constructed via a SA process. The multilayer buildup of doped polyaniline and sulfonated polystyrene (PANi/SPS) is facilitated by the electrostatic attraction between the delocalized positive -charged defects along the PANi backbone and the negative charges present in the ionizable pendant sulfonic acid groups of the SPS. Uniform multilayer thin films with thicknesses between 20 A and 100 A were constructed on different surfaces with complex topologies. Conductivities in the level of 0.1-1 S/cm were achieved by doping the multilayer PANi/SPS films with 1 M HCl. This level of conductivity was achieved by films with as few as 4 layers of PANi/SPS, that is, films with thicknesses of about 200 A. The lower conductivities attained by thinner films were attributed to the lack of formation of continuous conductive PANi pathways. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617 -253-5668; Fax 617-253-1690.) (Abstract shortened by UMI.).

Cheung, Josephine Ho-Wah

 
 
 
 
301

Polymer dynamics and ion conduction in modified soluble starch  

Science.gov (United States)

The dynamics of neat and plasticized carboxylated starch is investigated using broadband dielectric relaxation spectroscopy (DRS). The sodium single ion conductor is prepared by a 2,2,6,6- tetramethylpiperidin-1-oxyl (TEMPO) mediated oxidation process, in which the primary hydroxyl groups in alpha-D-glucose units are replaced by carboxylic salts. DRS measurements show that the ionic conductivity increases with increasing degree of oxidation. For example, 78 percent carboxylated starch with 25 weight percent glycerol displays around 3 orders of magnitude higher ionic conductivity than the comparable glycerol- plasticized 25 percent carboxylated material, principally due to the higher content of mobile cations. The role of salts and plasticizers including water on the relaxation behavior of amylose-rich starch is explored. Other complimentary techniques are used in the investigation, including FTIR, XRD and DSC.

Lee, Hyungki; Runt, James

2009-03-01

302

Formation of Wigner crystals in conducting polymer nanowires  

CERN Document Server

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

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

2007-01-01

303

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

304

Effect of low energy oxygen ion beam irradiation on ionic conductivity of solid polymer electrolyte  

Energy Technology Data Exchange (ETDEWEB)

Over the past three decades, solid polymer electrolytes (SPEs) have drawn significant attention of researchers due to their prospective commercial applications in high energy-density batteries, electrochemical sensors and super-capacitors. The optimum conductivity required for such applications is about 10{sup ?2} – 10{sup ?4} S/cm, which is hard to achieve in these systems. It is known that the increase in the concentration of salt in the host polymer results in a continuous increase in the ionic conductivity. However, there is a critical concentration of the salt beyond which the conductivity decreases due to formation of ion pairs with no net charge. In the present study, an attempt is made to identify the concentration at which ion pair formation occurs in PEO: RbBr. We have attempted to modify microstructure of the host polymer matrix by low energy ion (Oxygen ion, O{sup +1} with energy 100 keV) irradiation. Ionic conductivity measurements in these systems were carried out using Impedance Spectroscopy before and after irradiation to different fluencies of the oxygen ion. It is observed that the conductivity increases by one order in magnitude. The increase in ionic conductivity may be attributed to the enhanced segmental motion of the polymer chains. The study reveals the importance of ion irradiation as an effective tool to enhance conductivity in SPEs.

Manjunatha, H., E-mail: gnk-swamy@blr.amrita.edu; Kumaraswamy, G. N., E-mail: gnk-swamy@blr.amrita.edu [Department of Physics, Amrita Vishwa Vidyapeetham, Bengaluru-560035 (India); Damle, R. [Department of Physics, Bangalore University, Bengaluru-560056 (India)

2014-04-24

305

Effect of low energy oxygen ion beam irradiation on ionic conductivity of solid polymer electrolyte  

International Nuclear Information System (INIS)

Over the past three decades, solid polymer electrolytes (SPEs) have drawn significant attention of researchers due to their prospective commercial applications in high energy-density batteries, electrochemical sensors and super-capacitors. The optimum conductivity required for such applications is about 10?2 – 10?4 S/cm, which is hard to achieve in these systems. It is known that the increase in the concentration of salt in the host polymer results in a continuous increase in the ionic conductivity. However, there is a critical concentration of the salt beyond which the conductivity decreases due to formation of ion pairs with no net charge. In the present study, an attempt is made to identify the concentration at which ion pair formation occurs in PEO: RbBr. We have attempted to modify microstructure of the host polymer matrix by low energy ion (Oxygen ion, O+1 with energy 100 keV) irradiation. Ionic conductivity measurements in these systems were carried out using Impedance Spectroscopy before and after irradiation to different fluencies of the oxygen ion. It is observed that the conductivity increases by one order in magnitude. The increase in ionic conductivity may be attributed to the enhanced segmental motion of the polymer chains. The study reveals the importance of ion irradiation as an effective tool to enhance conductivity in SPEs

306

Formation of Wigner crystals in conducting polymer nanowires  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The search for theoretically predicted Wigner crystal in one-dimensional (1D) wires of structurally disordered materials exhibiting properties of charge-density-waves have remained unsuccessful. Based on the results of a low temperature conductivity study we report here formation of such 1D Wigner crystal (1DWC) in polypyrrole nanowires having low electron densities. The current-voltage characteristics of all the nanowires show a 'gap' that decreases rapidly as the temperatu...

Rahman, Atikur; Sanyal, Milan K.

2007-01-01

307

Fabrication of chemiluminescence sensor based on conducting polymer@SiO2/Nafion composite film.  

Science.gov (United States)

Tris(2,2'-bipyridyl)ruthenium (II) (Ru(bpy)2+) electrogerated chemiluminescence (ECL) sensor was fabricated by immobilization of Ru(bpy)2+ complex on conducting polymer@SiO2/Nafion composite film on surface of glassy carbon electrode. The conducting polymer@SiO2 nanocomposites were prepared by coating polyaniline (PANI), polypyrrole (PPy), and polythiophene (PTh) on the surface of the SiO2 sphere. The conducting polymer@SiO2 nanocomposite was characterized by scanning electron microscopy (SEM), Transmission electron microscopy (TEM), and atomic force microscopy (AFM). The sensitivity and reproducibility of the prepared ECL sensor to tripropylamine (TPA) was evaluated. As a result, the PPy@SiO2 composite electrode exhibited high sensitivity and good reproducibility compared to that obtained with PANI@SiO2 and PTh@SiO2 composite electrodes because of the strong interaction between PPy@SiO2 and Ru(bpy)2+ complex. PMID:21137811

Jung, Da-Jung; Piao, Ming-Hua; Oh, Sang-Hyub; Woo, Jin-Chun; Choi, Seong-Ho

2010-10-01

308

Studies on the Sensing Mechanism of Conducting Polymer for Volatile Organic Compound Sensing  

Energy Technology Data Exchange (ETDEWEB)

In this study, we fabricated chemically polymerized PPy and PANi films with different selectivity by controlling dedoping time. And the sensing properties and mechanism of VOCs adsorption to conducting polymers were investigated. Thin sensor had higher sensitivity compared to thick one, and dedoped sensor for 1-minute highest sensitivity. Upon gas absorption, polypyrrole exhibited positive sensitivity while polyaniline had negative sensitivity. PPy film show hydrophilic property and PANi film show hydrophobic property. After the gas absorption, the sensitivity increased as a function of polarity of absorbed molecules. These behaviors are due to the polar molecules absorbed with the movable polaron or free carrier, and then it interrupt or generate the movement of polaron and carrier, and then it changes the conductivity of polymer. We found that conducting polymer sensors are very sensitive to the difference in polarity of gas molecules. (author) 12 refs., 7 figs.

Hwang, H. R.; Paik, J. H.; Huh, J. S.; Lee, D. D.; Lim, J. O. [Kyungpook National University, Taegu (Korea); Lee, J.Y. [Sungkyunkwan University, Seoul (Korea)

2001-07-01

309

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

310

Electrochemical synthesis of electronic and ionic conductive polymer composite polyaniline/PEO network  

International Nuclear Information System (INIS)

A bilayer composite of conducting polyaniline was prepared by electrochemical polymerization of anilinium salt (dissolved in appropriate solvent like DMF, methanol, or water) in poly(ethylene oxide) PEO network. When washed, dried and doped with LiClO4, the bilayer showed electro-chemical activity corresponding to doping and undoping reactions in the solid state. The bilayer was characterized by FT-IR (reflection), UV spectroscopy and microscopic examination while the electrochemical activity in the solid state was examined by cyclic voltammetry. Cyclic voltammetry of the composite conductive polymer and polymer electrolyte in the solid state against Pt produced oxidation peaks at 0.26 and 0.78 V. Against Li, a broad oxidation peak appeared between 0.5 and 4.5; doping efficiency in the Li cell reached 95% between 2-4 V at a scan rate of 100 mV/s. The color of the conducting polymer as anode changed from transparent yellow to green and then to blue during the doping process. Cole-cole plots of the composite obtained by AC impedance measurements showed an arc at high frequency region (>2.82 MHx) due to polymer electrolyte impedance. Another arc due to impedance of the doping reaction, at lower frequency (>20 Hz) followed as doping of the conductive polymer preceeded; the arc is then joined by a Warburg line, which characterizes diffusion controlled kinetics at the low frequency region (<20 Hz). (auth.). 17 refs.; 14 figs. 2 tabsigs. 2 tabs

311

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

Energy Technology Data Exchange (ETDEWEB)

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.

Linde, Felix; Sekhar Yadavalli, Nataraja; Santer, Svetlana [Department of Experimental Physics, Institute for Physics and Astronomy, University of Potsdam, 14476 Potsdam (Germany)

2013-12-16

312

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

Science.gov (United States)

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.

Linde, Felix; Sekhar Yadavalli, Nataraja; Santer, Svetlana

2013-12-01

313

Electrochemical synthesis and characterization of conducting polymers in supercritical carbon dioxide.  

Science.gov (United States)

This contribution reports the first synthesis of conducting polymers (CPs), specifically, polyaniline (PAn) and polypyrrole (PPy), in supercritical carbon dioxide (scCO2). CPs synthesized electrochemically in scCO2 were characterized with cyclic voltammetry (CV), four-point probe conductivity, scanning electron microscopy (SEM), and UV-vis spectroscopy. Preliminary data indicate that CPs synthesized by this method exhibit novel morphology and high conductivity comparable to that synthesized by traditional methods. PMID:12197723

Anderson, Paul E; Badlani, Rachna N; Mayer, Jamie; Mabrouk, Patricia A

2002-09-01

314

Order-to-disorder structural transformation of a coordination polymer and its influence on proton conduction.  

Science.gov (United States)

We observed an ordered-to-disordered structural transformation in a Cu(2+) coordination polymer and investigated its influence on the proton conductivity. The transformation generated highly mobile proton carriers in the structure. The resulting material exhibited a conductivity greater than 10(-2) S cm(-1) at 130 °C. The structural transformation and the conduction mechanism were investigated by EXAFS, TPD-MS and NMR. PMID:25053211

Horike, Satoshi; Chen, Wenqian; Itakura, Tomoya; Inukai, Munehiro; Umeyama, Daiki; Asakura, Hiroyuki; Kitagawa, Susumu

2014-09-14

315

Designing of conducting polymer composites for shielding of microwave radiations  

Science.gov (United States)

Nanocomposites (NCs) possessing moderate conductivity and dielectric/magnetic properties were prepared by in-situ incorporation of different fillers [BaTiO3 (BT) and ?-Fe2O3 (FO) nanoparticles (NPs)] within polyaniline (PANI) matrix. Several compositions were prepared by keeping PANI:filler ratio as 2:1 and varying the FO:BT ratio of the NCs. The X-Ray diffraction patterns confirmed the formation of electrically conducting PANI and proper incorporation of BT or FO NPs. Similarly, HRTEM images and EDX elemental analysis confirm the formation of NCs and phase preservation of incorporated FO or BT NPS. The magnetization measurements revealed that incorporation of ?-Fe2O3 resulted in improvement in magnetic properties with saturation magnetization value of 12.8 emu/g. The microwave shielding studies in the 12.4-18.0 GHz frequency range (P-band) revealed that the among various NCs, refelction loss was minimum (-4.6 dB) for composition having BT:FO ratio of 1:1 (i.e. PBF3) probably due to better matching of input impedance. Further, the incorporation of BT and FO NPs leads to reduction of skin depth and additional dielectric/magnetic losses resulting in absorption loss of -20.2 dB. The total attenuation (T) of -24.8 dB (i.e. >99 % attenuation) demonstrate the potential of these NCs for making futuristic microwave shields.

Saini, Parveen; Barala, Sunil Kumar; Arora, Manju; Kotnala, R. K.

2013-06-01

316

Evidence of ratchet effect in nanowires of a conducting polymer  

CERN Document Server

Ratchet effect, observed in many systems starting from living organism to artificially designed device, is a manifestation of motion in asymmetric potential. Here we report results of a conductivity study of Polypyrrole nanowires, which have been prepared by a simple method to generate a variation of doping concentration along the length. This variation gives rise to an asymmetric potential profile that hinders the symmetry of the hopping process of charges and hence the value of measured resistance of these nanowires become sensitive to the direction of current flow. The asymmetry in resistance was found to increase with decreasing nanowire diameter and increasing temperature. The observed phenomena could be explained with the assumption that the spatial extension of localized state involved in hopping process reduces as the doping concentration reduces along the length of the nanowires.

Rahman, A; Gangopadhayy, R; De, A; Das, I

2006-01-01

317

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 presed/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.

318

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

Directory of Open Access Journals (Sweden)

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

Ulrich W. Scherer

2006-04-01

319

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

320

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.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. Electronic supplementary information (ESI) available: E-beam platinum bonding induced damage, estimation of contact resistance between nanofibers and suspended pads, effects of heat loss from suspended devices, estimation of heat loss along nanofibers, diameter calculation for beaded fibers, schematics of the electrospinning and WAXS setup, orientation analysis of the inter-fiber alignment, WAXS patterns from bulk samples, the WAXS data analysis strategy, and estimation of the crystallinity. See DOI: 10.1039/c4nr00547c

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

2014-06-01

 
 
 
 
321

Reversible shape memory of nanoscale deformations in inherently conducting polymers without reprogramming.  

Science.gov (United States)

By using inherently conducting polymers, we introduce new shape memory functionality for stimuli-responsive polymers. The shape memory process is unique in that it utilizes electrochemical control of the polymer redox state to conceal, and temporarily store, preformed nanoscale surface patterns, which can later be recalled. Unlike classical thermoset and thermoplastic shape memory polymers, the electrochemical control does not completely perturb the low entropy state of the deformed polymer chains, thus enabling the concept of reversible transition between the permanent and temporary shapes. This is demonstrated using electrochemical-atomic force microscopy/quartz crystal microbalance to characterize the modulation of nanoscale deformations in electroactive polybithiophene films. Experimental results reveal that cation/solvent exchange with the electrolyte and its effect on reconfiguration of the film structure is the mechanism behind the process. In addition to incorporating conductive properties into shape-memory polymers, the ability to reversibly modulate surface nanopatterns in a liquid environment is also of significant interest in tribology and biointerface applications. PMID:21401135

Higgins, Michael J; Grosse, Willo; Wagner, Klaudia; Molino, Paul J; Wallace, Gordon G

2011-04-01

322

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

Science.gov (United States)

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

Ates, Murat

2013-05-01

323

Investigations of conductive polymer coatings for corrosion protection of aluminum alloys  

Science.gov (United States)

The anti-corrosion properties of a novel double strand conductive polymer coating on aluminum alloys in salt environments as a possible replacement for chromium conversion coatings was investigated. The conductive coating consisted of a double helix backbone structure of polyaniline wrapped with an esterified polyacrylic acid strand. This polymer complex offers advantages over other conductive polymer systems in material stability and processability. The polymer is soluble in single organic solvents and was sprayed onto square AA7075-T6 and AA2024-T3 aluminum alloy samples. The coatings were investigated for corrosion protection properties using cyclic polarization, electrochemical impedance spectroscopy (EIS) and long term exposure in aggressive salt environments. The polymer coated samples were tested against two commercial chromate conversion coatings and uncoated alloy samples. The cyclic polarization tests show a two order of magnitude lowering of the corrosion current over the uncoated samples, a one order of magnitude lowering of Isbcorr over the second type of chromate coating and a one order of magnitude higher Isbcorr over the first type of chromate coating. Impedance results show a two order of magnitude higher impedance at low frequencies over the uncoated and equivalent performance for both types of chromate coatings. EIS and cyclic polarization tests of the conductive state (green colored) versus a non-conductive state (blue colored) of the polymer coating shows that the electrically conductive state is more effective than the insulating state for corrosion protection. This data indicates that the electro-active nature of the polymer coating plays a role in the protection of the alloys. After two months exposure in a.5N NaCl solution, there is no evidence of pitting at the alloy surface for the polymer coated samples under scanning electron microscopy (SEM) images, indicating a change in the typical corrosion mechanism for aluminum alloys. The molecular structure of the polymer coating may offer the ability to chelate with the aluminum oxide layer, the metal layer or reaction products. Other researchers studying inhibitor effects have shown that this chelation is one possible way to prevent or slow the pitting process on aluminum alloy surfaces.

Racicot, Robert James

324

Facile preparation of transparent and conductive polymer films based on silver nanowire/polycarbonate nanocomposites  

International Nuclear Information System (INIS)

Silver nanowires (AgNW) synthesized by a solvothermal method were incorporated into a polycarbonate matrix by a solution mixing procedure. Films with a thickness around 18 ?m were obtained, showing a good distribution of the wires within the polymer matrix. The thermal stability of the polymer matrix increased significantly, with the main decomposition peak shifting up to 74?° C for an AgNW loading of 4.35 wt%. The percolation threshold was obtained at very low AgNW content (0.04 wt%), and the composite electrical conductivity at the maximum loading (4.35 wt%) was 41.3 ? cm. Excellent transparency was obtained at the percolation threshold, with negligible reduction in the transmittance of the polymer matrix (from 88.2 to 87.6% at 0.04 wt% loading of AgNW). In addition, the polymer matrix protected the silver nanowires from oxidation, as demonstrated by the XPS analysis. (paper)

325

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)

326

Heat capacity, magnetic susceptibility, EPR, and dc conductivity of some conducting polymers  

Science.gov (United States)

Polyaniline doped with polystyrene-sulfonic-acid (PAN-PSSA), such that y =[sulfonate]/[aniline] = 1, exhibits a dc conductivity of 0.1 S/cm. On increasing the dopant concentration to y = 6, the conductivity drops by four orders of magnitude. Poly(3,4-ethylenedioxythiophene) doped with polystyrene-sulfonic-acid (PEDOT-PSSA) also exhibits a similar behavior on doping. The results of a study involving heat capacity, magnetic susceptibility, EPR, and dc conducting measurements will be reported.

Kahol, Pawan; Ho, James; Deterich, Stefania; Chen, Y. Y.; Wang, C. R.; Neeleshwar, S.; Tsai, C. B.; Wessling, B.

2004-03-01

327

Nanofiber preparation by whisker method using solvent-soluble conducting polymers  

International Nuclear Information System (INIS)

We prepared conducting polymer nanofibers by means of whisker formation in a solution by using solvent-soluble conducting polymers with alkyl or alkoxy side chains. A morphological characterization using an atomic force microscope indicated that they have one-dimensional nanofibrillar structures with typical heights of 3-10 nm. The conductivity of a single poly(3-hexylthiophene) (P3HT) nanofiber was measured using 300-nm-spacing Pt electrodes and the conductivity of 0.25 S/cm at 290 K was achieved by chemical doping using nitrosonium tetrafluoroborate. Considering the temperature dependence of the conductivity, the carrier transport in the single nanofiber was explained by a quasi-one-dimensional variable range-hopping model

328

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

329

Microfluidic enhanced conductive polymer microspheres for sensor applications  

Science.gov (United States)

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

Snyder, Jessica; Lu, Donglai; Shen, Amy

2010-11-01

330

Electrical and Optical Properties of a Novel Nonconjugated Conductive Polymer, Polynorbornene  

Science.gov (United States)

We report electrical and optical properties of a novel nonconjugated conductive polymer, polynorbornene which has an isolated double bond in the repeat. Electrical conductivity of this polymer increases by more than ten orders of magnitude to about 0.01 S/cm upon doping with iodine. Optical absorption measurements of the polymer film have been made at different dopant concentrations. For a lightly doped polymer, two absorption peaks: one corresponding to cation radicals and the other corresponding to charge transfer between the double bond and the dopant were observed at 4.20 eV (295nm) and 3.13 eV (396nm) respectively. FTIR spectroscopic measurements have shown a reduction in the intensity of the C=C stretching and =C-H bending vibration bands upon doping indicating formation of radical cations. Photoluminescence studies have shown an emission band with a peak at ˜ 425nm when excited at 300nm. Nonlinear optical studies of this novel nonconjugated conductive polymer are in progress.

Narayanan, Ananthakrishnan; Palthi, Aditya Kumar; Thakur, Mrinal

2008-03-01

331

Optical studies of conducting polymers in metallic and semiconducting doped states  

Science.gov (United States)

A study of electromagnetic response was performed at direct current (DC), microwave (6.5 GHz) and optical (15--40,000 cm-1) frequencies on poly (3,4-alkylenedioxythiophenes) (PADOTs) doped with various dopants near the insulator-metal transition together with structural studies (X-ray diffraction). We find these materials to be inhomogeneous, i.e. to have well defined crystalline regions within amorphous media. The transport measurements indicate that the properties of PADOTs vary from insulating to metallic. The metallic state of PADOTs follows trends found previously for the metallic polyaniline and polypyrrole thus confirming the universality of the metallic state for conducting polymers. The features of this state are the positive temperature coefficient of reduced activation energy, negative dielectric response at mw and far infrared frequencies, unique frequency dependence of the dielectric function and optical conductivity. A chain-linked network of metallic grains model is used in the discussion of experimental results. Within this model the transport in metallic conducting polymers is described by three basic electronic processes: intragrain scattering, diffusive spreading within the grains and the resonance hopping between the grains. The latter process is responsible for the negative dielectric responce and very long relaxation times characteristic for the metallic state of the conducting polymers. To further probe the metallic state of conducting polymers the polarized optical together with microwave and DC conductivity studies on stretch oriented films of polyaniline were performed in directions parallel and perpendicular to the stretch orientation. The low energy (far infrared and microwave) dielectric response was found to be negative for both directions. Together with the positive temperature coefficient of the reduced activation energy observed for parallel and perpendicular directions this proves the metallic state in conducting polymers is three-dimensional. Also included in this thesis is the study of LiCl treated emeraldine base (EB) form of polyaniline. We find that Li+ dopes EB based on the observation of new electronic states in the bandgap and associated with them spins. However, even at the maximum doping level LiCl doped polyaniline is a strongly localized charged insulator, a conducting polymer in a doped semiconducting state. This conclusion is based on the low DC conductivity, low dielectric constant, rapid decrease of the oscillator strength to zero in the infrared, low magnetic susceptibility dominated by a weak Curie-like component, broad EPR linewidth and predominantly Gaussian lineshape of the EPR signal found for LiCl processed EB. The results for LiCl doped polyaniline are compared to other conjugated polymers in the semiconducting doped state. The strongly localized properties of LiCl doped EB are attributed to the formation of spinless defects such as bipolarons.

Saprigin, Alexey Vyacheslavovich

332

Conducting polymers and corrosion: Part 2 -- Polyaniline on aluminum alloys  

Energy Technology Data Exchange (ETDEWEB)

The electrochemical behavior of conducting polyaniline coatings on various aluminum alloys subjected to immersion in dilute Harrison solution (0.35% ammonium sulfate [(NH{sub 4}){sub 2}SO{sub 4}], 0.05% sodium chloride [NaCl]) was studied. Electrochemical impedance spectroscopy revealed that the charge-transfer resistance (R{sub ct}) of polyaniline-coated alloys increased as a function of immersion time. Polyaniline-coated platinum did not exhibit a significant increase in impedance under similar conditions, indicating that an active metal in contact with the polyaniline is required for the observed increase in R{sub ct}. A similar pattern of increasing R{sub ct} was observed for Alodine (Product A)-treated Al 7075T-6 (UNS A97075) alloys. Mean current and mean potential values obtained from electrochemical noise measurements also suggest a substantial electrochemical interaction between the polyaniline and the aluminum alloy during the early stages of immersion. Polarization experiments and open-circuit potential measurements revealed an ennobling of aluminum alloys to higher potential in the presence of polyaniline coatings. The corrosion protection afforded by a polyaniline/epoxy two-coat system on Al 2024T-3 (UNS A92024) alloy also was evaluated using impedance spectroscopy and compared with that for a single coat of epoxy on untreated and Product A-treated Al2024T-3 alloy. The Product A treatment and the polyaniline coating were found to increase the lifetime of the epoxy topcoat, although these two-coating systems exhibited rather different variations in low-frequency impedance with immersion time. A mechanism consistent with these observations was suggested.

Tallman, D.E.; Pae, Y.; Bierwagen, G.P.

2000-04-01

333

Nuclear magnetic resonance and conductivity study of starch based polymer electrolytes  

Energy Technology Data Exchange (ETDEWEB)

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

Lopes, L.V.S.; Dragunski, D.C.; Pawlicka, A.; Donoso, J.P

2003-06-30

334

Nuclear magnetic resonance and conductivity study of starch based polymer electrolytes  

International Nuclear Information System (INIS)

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

335

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

336

Conducting polymer-coated stainless steel bipolar plates for proton exchange membrane fuel cells (PEMFC)  

Energy Technology Data Exchange (ETDEWEB)

Stainless steel satisfies many of the requirements for proton exchange membrane (PEM) fuel cell bipolar plates except its corrosion under fuel cell operating conditions. Metal oxide formation leads to contact resistance, and metal dissolution can cause contamination of the membrane electrode assembly (MEA). These problems can be solved by coating stainless steel plates with corrosion resistant and conductive layers. In this study, 304 stainless steel was coated electrochemically with the conducting polymers polyaniline (PANI) and polypyrrole (PPY). Cyclic voltammetry was used for the polymerization and deposition of these polymers. The polymer-coated stainless steel plates were tested for corrosion and contact resistance under PEM fuel cell conditions, which showed improved corrosion resistance with acceptable contact resistance. (Author)

Joseph, Shine; McClure, J.C.; Chianelli, R.; Pich, P. [Texas Univ., El Paso, TX (United States); Sebastian, P.J. [UNAM, Centro de Investigation en Energia, Temixco, Morelos (Mexico)

2005-09-01

337

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

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english 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 conten [...] t of acid polar groups incorporated into the macromolecular chain. Polymeric films were produced by blending the sulfonated styrene-indene copolymer with poly(vinylidene fluoride). The degree of sulfonation of the polymer was strongly affected by the sulfonation reaction parameters, with a direct impact on the ionic exchange capacity and the ionic conductivity of the sulfonated polymers and the membranes obtained from them. The films produced with the blends showed more suitable mechanical properties, although the conductivity of the membranes was still lower than that of commercially available membranes used in fuel cells.

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

338

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

339

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

340

Conductivity and Dielectric Properties of Proton Conducting Poly (Vinyl) Chloride (PVC) Based Gel Polymer Electrolytes  

International Nuclear Information System (INIS)

Poly (vinyl) chloride (PVC)-NH4I-EC films have been prepared by the solution cast technique. The sample containing 30 wt. % NH4I exhibited the highest room temperature conductivity of 4.60 x 10-7 S cm-1. The conductivity increased to 1.08 x 10-6 S cm-1 when 15 wt. % of ethylene carbonate (EC) was added to 70 wt. % PVC - 30 wt. % NH4I. The effects of ethylene carbonate (EC) addition on the frequency dependent dielectric properties of PVC based electrolytes were investigated by electrochemical impedance spectroscopy (EIS), in the temperature range of 300 K to 373 K. The dielectric properties and ac conductivity of the samples prepared have been analyzed. The values of dielectric constant were found to increase with increasing conductivity of the samples. Analysis of the ac conductivity data revealed the electrolytes to be of the non-Debye type with conduction mechanism of the overlapping-large-polaron-tunneling (OLPT) model. (author)

 
 
 
 
341

Fabrication and properties of shape-memory polymer coated with conductive nanofiber paper  

Science.gov (United States)

A unique concept of shape-memory polymer (SMP) nanocomposites making up of carbon nanofiber paper was explored. The essential element of this method was to design and fabricate nanopaper with well-controlled and optimized network structure of carbon nanofibers. In this study, carbon nanofiber paper was prepared under ultrasonicated processing and vapor press method, while the dispersion of nanofiber was treated by BYK-191 dispersant. The morphologies of carbon nanofibers within the paper were characterized with scanning electron microscopy (SEM). In addition, the thermomechanical properties of SMP coated with carbon nanofiber paper were measured by the dynamic mechanical thermal analysis (DMTA). It was found that the glass transition temperature and thermomechanical properties of nanocomposites were strongly determined by the dispersion of polymer in conductive paper. Subsequently, the electrical conductivity of conductive paper and nanocomposites were measured, respectively. And experimental results revealed that the conductive properties of nanocoposites were significantly improved by carbon nanopaper, resulting in actuation driven by electrical resistive heating.

Lu, Haibao; Liu, Yanju; Gou, Jan; Leng, Jinsong

2009-07-01

342

Schemes for the use of conducting polymers as active materials in electrochemical supercapacitors  

Energy Technology Data Exchange (ETDEWEB)

The development of a novel conducting polymer based system for use in electrochemical capacitors is described. This system utilizes a new conducting polymer, poly-3-(4-fluorophenyl)-thiophene (PFPT), that can be reversibly n- and p-doped to high charge density. The electrochemical n-dopability of this material can be further improved by cycling in acetonitrile solution that contains a new electrolyte, tetramethylammonium trifluoromethanesulfonate (Me{sub 4}NCF{sub 3}SO{sub 3}). We discuss these improvements in n-dopability in terms of potential electronic and steric influences. We believe that the substituent fluorophenyl group does not communicate with the polythiophene backbone through resonance, and conclude that the ability to n-dope PFPT to high charge density may occur as a result of electron transfer reactions from the conducting polymer backbone into the substituent. This new system for electrochemical capacitors provides the best achievable performance from conducting polymers and generates high energy and power densities that are comparable with noble metal oxide systems, potentially at a fraction of the cost.

Rudge, A.; Davey, J.; Gottesfeld, S. [Los Alamos National Lab., NM (United States); Ferraris, J.P. [Texas Univ., Richardson, TX (United States). Dept. of Chemistry

1993-05-01

343

Schemes for the use of conducting polymers as active materials in electrochemical supercapacitors  

Energy Technology Data Exchange (ETDEWEB)

The development of a novel conducting polymer based system for use in electrochemical capacitors is described. This system utilizes a new conducting polymer, poly-3-(4-fluorophenyl)-thiophene (PFPT), that can be reversibly n- and p-doped to high charge density. The electrochemical n-dopability of this material can be further improved by cycling in acetonitrile solution that contains a new electrolyte, tetramethylammonium trifluoromethanesulfonate (Me[sub 4]NCF[sub 3]SO[sub 3]). We discuss these improvements in n-dopability in terms of potential electronic and steric influences. We believe that the substituent fluorophenyl group does not communicate with the polythiophene backbone through resonance, and conclude that the ability to n-dope PFPT to high charge density may occur as a result of electron transfer reactions from the conducting polymer backbone into the substituent. This new system for electrochemical capacitors provides the best achievable performance from conducting polymers and generates high energy and power densities that are comparable with noble metal oxide systems, potentially at a fraction of the cost.

Rudge, A.; Davey, J.; Gottesfeld, S. (Los Alamos National Lab., NM (United States)); Ferraris, J.P. (Texas Univ., Richardson, TX (United States). Dept. of Chemistry)

1993-01-01

344

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.

345

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

International Nuclear Information System (INIS)

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

346

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

347

Integration of microwave MEMS devices into rectangular waveguide with conductive polymer interposers  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper investigates a novel method of integrating microwave microelectromechanical systems (MEMS) chips into millimeter-wave rectangular waveguides. The fundamental difficulties of merging micromachined with macromachined microwave components, in particular, surface topography, roughness, mechanical stress points and air gaps interrupting the surface currents, are overcome by a double-side adhesive conductive polymer interposer. This interposer provides a uniform electrical contact, stabl...

Baghchehsaraei, Zargham; Sterner, Mikael; A?berg, Jan; Oberhammer, Joachim

2013-01-01

348

Patterning of Conducting Polymers Using UV Lithography: The In-Situ Polymerization Approach.  

Science.gov (United States)

In this paper we report on the in-situ polymerization of 3T with Cu(ClO4)2 inside several host polymers such as novolak-based negative-tone photoresist, polystyrene (PS), poly(4-vinylphenol) (P4VP) polymethylmethacrylate (PMMA) and poly(4-vinylphenol)-co-(methylmethacrylate) P4VP-co-MMA to form an interpenetrating polymer network (IPN). Conducting IPN films in the order of 10-4 to 150 S/cm are obtained depending on the specific IPN composition. Moreover, the convenience of this synthetic approach has been demonstrated using a commercially available negative-tone photoresist based on novolak as a host polymer. Novolak photoresist was properly formulated with 3T and Cu(ClO4)2 to preserve as far as possible the negative lithographic characteristics of novolak-based photoresist and generate conductive micropatterns by means of UV lithography. The CP is in-situ synthesized into the novolak matrix by a post-bake after the lithography process (exposure + development). The electrical conductivity of the patterned film is 10-2 S/cm. We accurately patterned three different types of microstructures with different resolutions: interdigitated structures with a width of 100 µm, 200 µm-side squares and a 20 µm-wide cross. We believe this synthetic approach is of potential application to modify the conductivity of numerous insulating polymers while preserving their physical and chemical properties. PMID:22866698

Abargues, Rafael; Rodríguez-Cantó, Pedro Javier; Garcia-Calzada, Raul; Martinez-Pastor, Juan

2012-08-01

349

Conductivity studies of LiCF3SO3 doped PVA: PVdF blend polymer electrolyte  

Science.gov (United States)

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.

Tamilselvi, P.; Hema, M.

2014-03-01

350

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

351

Influence of film thickness on the phase separation mechanism in ultrathin conducting polymer blend films.  

Science.gov (United States)

The film morphology of thin polymer blend films based on poly[(1-methoxy)-4-(2-ethylhexyloxy)-p-phenylenevinylene] (MEH-PPV) and poly(N-vinylcarbazole) (PVK) is probed as a function of film thickness. Blend films are prepared with spin-coating of polymer solutions with different concentrations on top of solid supports. The blending ratio of both conducting polymers is kept constant. The film and surface morphology is probed with grazing incidence ultrasmall-angle X-ray scattering (GIUSAXS) and atomic force microscopy (AFM). A linear dependence between the film thickness and the averaged phase separation is found. In addition, X-ray reflectivity measurements show an enrichment of PVK at the substrate interface. UV/vis spectroscopy measurements indicate a linearly increasing amount of both homopolymers in the blend films for increasing film thicknesses. The generalized knowledge about the influence of the film thickness on the phase separation behavior in conducting polymer blend films is finally used to describe the phase separation formation during the spin-coating process, and the results are discussed in the framework of an adapted Flory-Huggins theory for rodlike polymers. PMID:21370827

Meier, Robert; Ruderer, Matthias A; Diethert, Alexander; Kaune, Gunar; Körstgens, Volker; Roth, Stephan V; Müller-Buschbaum, Peter

2011-03-31

352

Surface excitation correction of the inelastic mean free path in selected conducting polymers  

International Nuclear Information System (INIS)

In earlier works, the inelastic mean free path (IMFP) of electrons was determined by elastic peak electron spectroscopy (EPES) using Ni and Ag reference standard samples, but fully neglecting surface excitation. Surface excitation that is characterized by the surface excitation parameter (SEP), and may affect considerably the elastic peak for the sample and the reference material. The SEP parameters of selected conducting polymers (polythiophenes, polyaniline and polyethylene) were determined by EPES using Si and Ge reference samples. Experiments were made with a hemispherical analyzer of energy resolution 100-200 meV in the E = 0.2-2.0 keV energy range. The composition of the sample surfaces was determined by in situ XPS, their surface roughness by AFM. The experimental SEP parameter data of eight polymer samples were determined by our new procedure, using the formulae of Chen and Werner et al. in the E = 0.2-2.0 keV energy range. The trial and error procedure is based on the best approach between the experimental and calculated IMFPs, corrected on surface excitation. The improvement in the SEP correction appears in the difference between the corrected and Monte Carlo calculated IMFPs, assuming Gries and Tanuma et al. IMFPs for polymers and standard, respectively. The term describing the improvement by SEP resulted in 50-72% (good correction for five polymers) 24% (poor correction for one polymer), 1-6% (no correction for two polymers). The 100% correction was not ac polymers). The 100% correction was not achieved, indicating that the difference between experimental and calculated IMFP cannot be entirely explained by surface excitation. Using the SEP data of Si and Ge reference samples based on Chen's and Werner's material parameter values resulted in similar SEP corrections for the polymer samples

353

Hot-pressed Ag+ Ion Conducting Glass-Polymer Electrolytes: Synthesis and Battery Application  

Scientific Electronic Library Online (English)

Full Text Available SciELO Portugal | Language: English Abstract in english Synthesis of new Ag+ ion conducting glass-polymer electrolytes (GPEs): (1-x) PEO: x [0.75(0.75AgI:0.25AgCl):0.25(Ag2O:P2O5)], where 0 [...] )], with conductivity (?) ? 6.0 × 10-6 S cm-1, was identified from the compositional dependent conductivity studies and this has been referred to as the Optimum Conducting Composition (OCC). Approximately three orders of conductivity enhancement have been achieved in GPE OCC from that of the pure polymer PEO. The glass-polymer complexation has been confirmed by SEM and DSC analysis. Ion transport parameters viz. ionic conductivity (?), ionic mobility (?), mobile ion concentration (n) and ionic transference number (tion) have been characterized using different experimental techniques. Solid-state polymeric batteries were fabricated using GPE OCC as electrolyte and the cell-potential discharge characteristics were studied under different load conditions at room temperature.

Angesh, Chandra.

2012-07-01

354

Gamma- and electron dose response of the electrical conductivity of polyaniline based polymer blends  

International Nuclear Information System (INIS)

Complete text of publication follows. Conducting polymers, also known as 'synthetic metals' have been the subject of widespread investigations over the past decade due to their very promising characteristics. Polyaniline (PANI) holds a special position among conducting polymers in that its most highly conducting doped form can be reached by protonic acid doping or oxidative doping. It was published earlier, that the electrical conductivity of some polyaniline based polymer composites increases to a significant extent when irradiated to gamma, electron or UV radiation. The aim of the present study was to measure the high frequency conductivity of blended films of PANI with poly(vinylchloride), PVC, and chlorinated poly(propylene) irradiated in air to different doses. In order to find the most suitable composition od these composites the mass percentage of PANI within the PPCl and PVC matrix was changed between 5 - 30%. These samples were then gamma irradiated and the induced electrical conductivity was measured in the 1 kHz - 1 MHz frequency range to determine the most sensitive evaluation conditions. After selecting both the most suitable measuring conditions as well as the blend compositions the dose response of the chosen samples was determined in the dose range of 10 - 250 kGy. With respect to potential dosimetry application the effect of electron irradiation, the effect of irradiation temperature and the stability of the irradiated samples have also been investigated

355

Nanotechnology-the key to unlocking the intrinsic properties of inherently conducting polymers  

International Nuclear Information System (INIS)

Full text: Currently the properties of inherently conducting polymers (ICPs) such as polypyrroles, polythiophenes and polyanilines at the macroscopic level is limited by our ability to unlock the inherent electronic and electrochemical properties they possess at the nanodimension. It is known that the macroscopic structures consist of highly conducting nanodimensional islands separated by a sea of less conducting material. It is also known that incredibly fast and discrete electrochemical switching can be obtained if nanowire ICP electrodes are used instead of larger structures. In our recent work several approaches for the synthesis and fabrication of controlled nanodimensional structures based on inherently conducting polymers have been investigated. The simplest involves chemical oxidation of monomer in an inverse microemulsion to produce polyaniline nanoparticles. The second approach involves use of a flow-through electrolytic method which enables production of nanoparticles of tightly controlled dimensions. Conducting polymer nanostructures have also been produced in our laboratories using an inverse synthetic opal approach wherein ICPs are synthesized within the interstitial volume of ordered nanoparticles. In a different strategy we have utilized the unusual properties of carbon nanotubes (high strength and conductivity) to produce ICP nanostructures. This has been achieved by using water soluble conducting polymer as a dispersant prior to making CNT structures or by individually coating arrays (forests) of aligned carbon nanotubes. The former approach has been used to produce CNT structures with high charge storage capabilities while the latter has presented a convenient route to ICP based biosensor surfaces with enhanced performance characteristics. Each of the above approaches to development of ICP nanocomponents and the properties of these unique structures will be discussed here

356

Self-Assembly of Octapod-Shaped Colloidal Nanocrystals into a Hexagonal Ballerina Network Embedded in a Thin Polymer Film  

Science.gov (United States)

Nanoparticles with unconventional shapes may exhibit different types of assembly architectures that depend critically on the environmental conditions under which they are formed. Here, we demonstrate how the presence of polymer (polymethyl methacrylate, PMMA) molecules in a solution, in which CdSe(core)/CdS(pods) octapods are initially dispersed, affects the octapod-polymer organization upon solvent evaporation. We show that a fast drop-drying process can induce a remarkable two-dimensional (2D) self-assembly of octapods at the polymer/air interface. In the resulting structure, each octapod is oriented like a “ballerina”, that is, only one pod sticks out of the polymer film and is perpendicular to the polymer–air interface, while the opposite pod (with respect to the octapod’s center) is fully immersed in the film and points toward the substrate, like a ballerina performing a grand battement. In some areas, a hexagonal-like pattern is formed by the ballerinas in which the six nonvertical pods, which are all embedded in the film, maintain a pod–pod parallel configuration with respect to neighboring particles. We hypothesize that the mechanism responsible for such a self-assembly is based on a fast adsorption of the octapods from bulk solution to the droplet/air interface during the early stages of solvent evaporation. At this interface, the octapods maintain enough rotational freedom to organize mutually in a pod–pod parallel configuration between neighboring octapods. As the solvent evaporates, the octapods form a ballerina-rich octapod-polymer composite in which the octapods are in close contact with the substrate. Finally, we found that the resulting octapod-polymer composite is less hydrophilic than the polymer-only film. PMID:24447264

2014-01-01

357

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

Energy Technology Data Exchange (ETDEWEB)

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

Sandi, Giselle [Chemistry Division, Argonne National Laboratory, 9700 South Cass Ave., Argonne, IL 60439 (United States)]. E-mail: gsandi@anl.gov; Kizilel, Riza [Chemical and Environmental Engineering Department, Illinois Institute of Technology, Chicago, IL 60616 (United States); Carrado, Kathleen A. [Chemistry Division, Argonne National Laboratory, 9700 South Cass Ave., Argonne, IL 60439 (United States); Fernandez-Saavedra, Rocio [Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, 28049 Madrid (Spain); Castagnola, Norma [Chemistry Division, Argonne National Laboratory, 9700 South Cass Ave., Argonne, IL 60439 (United States)

2005-06-30

358

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

Scientific Electronic Library Online (English)

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

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

1997-10-01

359

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

Scientific Electronic Library Online (English)

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

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

360

Electrochromic conductive polymer fuses for hybrid organic/inorganic semiconductor memories  

Science.gov (United States)

We demonstrate a nonvolatile, write-once-read-many-times (WORM) memory device employing a hybrid organic/inorganic semiconductor architecture consisting of thin film p-i-n silicon diode on a stainless steel substrate integrated in series with a conductive polymer fuse. The nonlinearity of the silicon diodes enables a passive matrix memory architecture, while the conductive polyethylenedioxythiophene:polystyrene sulfonic acid polymer serves as a reliable switch with fuse-like behavior for data storage. The polymer can be switched at ˜2 ?s, resulting in a permanent decrease of conductivity of the memory pixel by up to a factor of 103. The switching mechanism is primarily due to a current and thermally dependent redox reaction in the polymer, limited by the double injection of both holes and electrons. The switched device performance does not degrade after many thousand read cycles in ambient at room temperature. Our results suggest that low cost, organic/inorganic WORM memories are feasible for light weight, high density, robust, and fast archival storage applications.

Möller, Sven; Forrest, Stephen R.; Perlov, Craig; Jackson, Warren; Taussig, Carl

2003-12-01

 
 
 
 
361

Creating Opal Templated Continuous Conducting Polymer Films with Ultralow Percolation Thresholds Using Thermally Stable Nanoparticles  

Science.gov (United States)

We propose a novel and robust strategy for creating continuous conducting polymer films with ultralow percolation thresholds using polymer-coated gold nanoparticles (Au NPs) as surfactant. Continuous poly(triphenylamine) (PTPA) films of high internal phase polymeric emulsions were fabricated using an assembly of crosslinked polystyrene (PS) colloidal particles as template. Polymer-coated Au NPs localize at the PS/PTPA interface and function as surfactant to efficiently produce a continuous conducting PTPA polymer film with very low percolation thresholds. The volume fraction threshold for percolation of the PTPA phase with insulating PS colloids was found to be 0.20. In contrast, with the addition of an extremely low volume fraction of surfactant Au NPs, the volume fraction threshold for percolation of the PTPA phase was dramatically reduced to 0.05. The SEM and TEM measurements clearly demonstrated the formation of a continuous PTPA phase within the polyhedral phase of PS colloids. To elucidate the influence of the nanoparticle surfactant on the blend films, the morphology and conductivity of the blends at different PS colloid/PTPA volume ratios were carefully characterized as a function of the Au NP concentration.

Kang, D. J.; Kwon, T.; Kim, M. P.; Kim, B. J.; Jung, H.; Bang, J.

2012-02-01

362

Control of conducting polymer actuators without physical feedback: simulated feedback control approach with particle swarm optimization  

Science.gov (United States)

Conducting polymer actuators have shown significant potential in articulating micro instruments, manipulation devices, and robotics. However, implementing a feedback control strategy to enhance their positioning ability and accuracy in any application requires a feedback sensor, which is extremely large in size compared to the size of the actuators. Therefore, this paper proposes a new sensorless control scheme without the use of a position feedback sensor. With the help of the system identification technique and particle swarm optimization, the control scheme, which we call the simulated feedback control system, showed a satisfactory command tracking performance for the conducting polymer actuator’s step and dynamic displacement responses, especially under a disturbance, without needing a physical feedback loop, but using a simulated feedback loop. The primary contribution of this study is to propose and experimentally evaluate the simulated feedback control scheme for a class of the conducting polymer actuators known as tri-layer polymer actuators, which can operate both in dry and wet media. This control approach can also be extended to other smart actuators or systems, for which the feedback control based on external sensing is impractical.

Xiang, Xingcan; Mutlu, Rahim; Alici, Gursel; Li, Weihua

2014-03-01

363

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

CERN Document Server

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

Zimbovskaya, N A

2006-01-01

364

Synthesis and characterization of thiol-functionalized polymer as binder in conductive ink  

Science.gov (United States)

The technology of electrical printing has received industrial and scientific attention due to wide variety of application such as sensors, radio frequency identification cards (RFIDs), flexible display, and flexible solar cell. Especially a roll to roll gravure printing technique has been useful for mass production of electrical products. For the more high quality of conductive ink, the compatibility of organic binder and inorganic filler is very important. In this study, Thiol-functionalized polymer and core-shell conductive nanoparticles were used as the binder and filler. The thiol moieties in binder contribute to functionality of the synthesized polymer. Also, the conductivity and viscosity of synthesized ink and compatibility of filler with binder were characterized in various conditions.

Lee, Jungmin; Varadan, Vijay K.

2011-04-01

365

Characteristics of organic light-emitting diodes with conducting polymer anodes on plastic substrates  

Science.gov (United States)

The fabrication of conducting polymer films by a screen-printing method and characterization of an organic light-emitting diode (OLED) implemented using these films as an anode on plastic substrates are reported. Organic transparent electrode materials containing poly(3,4-ethylenedioxythiophene) (PEDOT) doped with poly(styrenesulfonic acid) (PSS) (PEDOT:PSS) were used after the modification by a unique nanoparticle binder design. The electro-optical properties as well as mechanical stabilities of these films were measured. The OLED performances when employing these films were comparable to that of OLEDs using indium tin oxide (ITO) despite their relatively poor conductivity. An external quantum efficiency of the OLED using this anode is ˜3.5%, which is about twice as that of OLEDs using ITO. These results show that the organic transparent electrode of a conducting polymer film patterned by the screen-printing method is a potential candidate for an electrode of the flexible OLED.

Huh, Jin Woo; Kim, Young Min; Park, Young Wook; Choi, Jin Hwan; Lee, Jin Woo; Lee, Jong Woo; Yang, Jae Woong; Ju, Sung Hoo; Paek, Kyeong Kap; Ju, Byeong Kwon

2008-02-01

366

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

Science.gov (United States)

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

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

2010-03-01

367

Synthesis and properties of a cation-conducting, high temperature polymer electrolyte  

Energy Technology Data Exchange (ETDEWEB)

A new class of polymer electrolyte, high temperature polymer electroltyes, as an electrolyte in high discharge rate batteries is proposed. As an initial effort in the development of these materials, sodium and lithium salts of sulfonated poly(p-phenyleneterephtalamide) have been prepared. DSC and electrical conductivity studies have been performed on these films. The conductivity exhibits Arrhenius behavior over the temperature range in which they are thermally stable (180-240 C) with the material containing sodium being more conductive than those containing lithium. Although the electrical performance of these materials is inadequate from a practical standpoint, it is suggested that with additional development these materials could function as electrolytes for high discharge rate batteries. (orig.)

Okamoto, Y. (Dept. of Chemistry, Polytechnic Univ., Brooklyn, NY (United States)); Xu, Z.S. (Dept. of Chemistry, Polytechnic Univ., Brooklyn, NY (United States)); McLin, M.G. (Physics Dept., U.S. Naval Academy, Annapolis, MD (United States)); Fontanella, J.J. (Physics Dept., U.S. Naval Academy, Annapolis, MD (United States)); Pak, Y.S. (Physics Dept., Hunter Coll. of CUNY, New York (United States)); Greenbaum, S.G. (Physics Dept., Hunter Coll. of CUNY, New York (United States))

1993-03-01

368

Enhancing the electrical conductivity of a hybrid POSS-PCL/graphene nanocomposite polymer.  

Science.gov (United States)

An electrically conductive polymer using polyhedral oligomeric silsesquioxane (POSS) nanocage incorporated into a modified poly [caprolactone based urea-urethane] (PCL)/graphene hybrid nanocomposite is described. Multilayer graphene flakes (8nm) were homogeneously dispersed into POSS-PCL at 0.1, 2, 5, and 10wt.% concentrations. This dispersion process of the graphene flakes was achieved by the use of stable dimethylacetamide (DMAc), via solution intercalation with POSS-PCL nanocomposites. The impedance spectroscopy of 5.0wt.% and higher concentration of graphene in POSS-PCL represented major improvement in conductivity over pristine POSS-PCL. The percolation threshold occurred at 5.0wt.% graphene concentration, converting the insulator POSS-PCL into a conductive POSS-PCL/graphene hybrid nanocomposite. The structures of the obtained hybrid materials were characterized with atomic force microscopy (AFM), Fourier transform infra-red (FT-IR), and Raman spectroscopy. The conductivity of the resultant nanocomposite polymer was investigated with electrochemical impedance spectroscopy (EIS). Herein, for the first time, we demonstrate a facile method of synthesizing, and describe the electrical properties of a conductive POSS-PCL/graphene nanocomposite polymer. PMID:25240216

Nezakati, Toktam; Tan, Aaron; Seifalian, Alexander M

2014-12-01

369

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

Science.gov (United States)

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-live neural cell electrode. We found that neural cells could be exposed to working concentrations (0.01 m) of the EDOT monomer for as long as 72 h while maintaining 80% cell viability. PEDOT could be electrochemically deposited around neurons cultured on electrodes using 0.5-1 microA/mm(2) galvanostatic current. PEDOT polymerized on the electrode and surrounded the cells, covering cell processes. The polymerization was impeded in regions where cells were well adhered to the substrate. The cells could be removed from the PEDOT matrix to generate a neural cell-templated biomimetic conductive substrate with cell-shaped features that were cell attracting. Live cells embedded within the conductive polymer matrix remained viable for at least 120 h following polymerization. Dying cells primarily underwent apoptotic cell death. PEDOT, PEDOT+live neurons, and neuron-templated PEDOT coatings on electrodes significantly enhanced the electrical properties as compared to the bare electrode as indicated by decreased electrical impedance of 1-1.5 orders of magnitude at 0.01-1 kHz and significantly increased charge transfer capacity. PEDOT coatings showed a decrease of the phase angle of the impedance from roughly 80 degrees for the bare electrode to 5-35 degrees at frequencies >0.1 kHz. Equivalent circuit modeling indicated that PEDOT-coated electrodes were best described by R(C(RT)) circuit. We found that an RC parallel circuit must be added to the model for PEDOT+live neuron and neuron-templated PEDOT coatings. PMID:17169420

Richardson-Burns, Sarah M; Hendricks, Jeffrey L; Foster, Brian; Povlich, Laura K; Kim, Dong-Hwan; Martin, David C

2007-03-01

370

Novel silver containing polymers for preparation of conducting nano materials using electron beam irradiation  

International Nuclear Information System (INIS)

Recently, silver nano materials have gained a lot of attentions in a variety of applications due to the unique biological, optical, and electrical properties. Among them, researchers have studied the preparation of nano materials using electron beam irradiation. Electron beam technique has many advantages over other techniques such as short reaction time, simple operation and absence of chemical residues after the reaction. In this study, we design and synthesize the novel silver containing polymers for preparation of conducting nano materials. Various silver nano materials having different sizes and shapes are prepared by control the polymer structures and electron beam irradiation conditions. The morphology and chemical composition of the polymers and nano materials are characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction

371

Electrically Conductive, Optically Transparent Polymer/Carbon Nanotube Composites and Process for Preparation Thereof  

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, Joseph G. (Inventor); Harrison, Joycelyn S. (Inventor); Park, Cheol (Inventor); Watson, Kent A. (Inventor); Ounaies, Zoubeida (Inventor)

2011-01-01

372

Comparison of solar cell performance of conducting polymer dyes with different functional groups  

Science.gov (United States)

Conductive polymer precursors, including carboxylic acid, cyano groups, amino groups, 5,2?:5?,2?-terthiophene-3?-carboxylic acid (TTCA), 3?-cyano-5,2?:5?,2?-terthiophene (CTT), and 3?,4?-diamino-2,2?:5?,2?-terthiophene (DATT) are synthesized. Electrochemically polymerized films of the precursors on a nanocrystalline TiO2 layer are examined as photo sensitizers, and the cell performance is compared. The photovoltaic cells are assembled with a polymer-coated TiO2 layer treated with TiCl4 as an anode and a Pt layer as a cathode in a propionitrile solution containing an iodide ion-based redox electrolyte. The charge-transfer processes of polymer-dyed cells are studied using impedance spectroscopy. The polymer dyes on the TiO2 surfaces are characterized by scanning electron microscope (SEM), atomic force microscope (AFM), transmission electron microscope (TEM), and X-ray photoelectron spectroscopy (XPS). XPS results show that the conducting polymer dye, bearing a carboxylic acid group, is more strongly bound to the TiO2 layer in comparison with other groups. Various experimental parameters affecting the cell efficiency are optimized, including the scan rate, number of potential cycles, and terthiophene monomer concentration. Of these polymers, the best cell efficiency is attained for poly-TTCA containing a carboxylic acid group. The optimized cell with the poly-TTCA dye shows a short-circuit current of 6.78 mA cm-2, an open-circuit voltage of 0.54 V, and a fill factor of 63.6. An energy conversion efficiency of 2.32% is obtained with a cell area of 0.24 cm2 under an air mass 1.5 solar simulated light irradiation of 100 mW cm-2.

Yoon, Jang-Hee; Kim, Dong-Min; Yoon, Sang-Su; Won, Mi-Sook; Shim, Yoon-Bo

2011-10-01

373

Protection of Conductive and Non-conductive Advanced Polymer-based Paints from Highly Aggressive Oxidative Environments  

Science.gov (United States)

Research has been continued to further improve the space durability of conductive and non-conductive polymer-based paints and of conductive thermal control paints for space applications. Efforts have been made to enhance the space durability and stability of functional Characteristics in ground-based space environment imitating conditions, using specially developed surface modification treatment. The results of surface modification of new conductive paints, including the ground-based testing in aggressive oxidative environments, such as atomic oxygen/UV and oxygen plasma, and performance evaluation are presented. Functional properties and performance characteristics, such as thermal optical properties (differential solar absorptance and thermal emittance representing the thermal optical performance of thermal control paints) and surface resistivity characteristics of pristine, surface modified, and tested materials were verified. Extensive surface analysis studies have been performed using complementary surface analyses including SEM/EDS and XPS. Test results revealed that the successfully treated materials exhibit reduced mass loss and no surface morphology change, thus indicating good protection from the severe oxidative environment. It was demonstrated that the developed surface modification treatment could be applied successfully to charge dissipative and conductive paints.

Gudimenko, Y.; Ng, R.; Iskanderova, Z.; Kleiman, J.; Grigorevsky, A.; Kiseleva, L.; Finckenor, M.; Edwards, D.

2005-01-01

374

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

International Nuclear Information System (INIS)

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

375

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

Science.gov (United States)

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

Choi, Hwa-Jeong; Song, Young-Min; Chung, Ildoo; Ryu, Kwang-Sun; Jo, Nam-Ju

2009-02-01

376

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

DEFF Research Database (Denmark)

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

Hansen, Thomas Steen; West, Keld

2007-01-01

377

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

DEFF Research Database (Denmark)

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

Hansen, Thomas Steen; Hassager, Ole

2007-01-01

378

TITANIUM DIOXIDE TRIADS FOR IMPROVED CHARGE-SEPARATION USING CONDUCTIVE POLYMERS  

Energy Technology Data Exchange (ETDEWEB)

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

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

2009-01-01

379

Polymer Nanofibers with Outstanding Thermal Conductivity and Thermal Stability: Fundamental Linkage between Molecular Characteristics and Macroscopic Thermal Properties  

CERN Document Server

Polymer nanofibers with high thermal conductivities and outstanding thermal stabilities are highly desirable in heat transfer-critical applications such as thermal management, heat exchangers and energy storage. In this work, we unlock the fundamental relations between the thermal conductivity and thermal stability of polymer nanofibers and their molecular characteristics by studying the temperature-induced phase transitions and thermal transport of a series of polymer nanofibers. Ten different polymer nanofibers with systematically chosen molecular structures are studied using large scale molecular dynamics simulations. We found that high thermal conductivity and good thermal stability can be achieved in polymers with rigid backbones, exemplified by {\\pi}-conjugated polymers, due to suppressed segmental rotations and large phonon group velocities. The low probability of segmental rotation does not only prevent temperature-induced phase transition but also enables long phonon mean free paths due to reduced di...

Zhang, Teng; Luo, Tengfei

2014-01-01

380

Correlated conformation and charge transport in multiwall carbon nanotube-conducting polymer nanocomposites  

Science.gov (United States)

The strikingly different charge transport behaviours in nanocomposites of multiwall carbon nanotubes (MWNTs) and conducting polymer polyethylenedioxythiophene-polystyrene-sulfonic-acid (PEDOT-PSS) at low temperatures are explained by probing their conformational properties using small-angle x-ray scattering (SAXS). The SAXS studies indicate the assembly of elongated PEDOT-PSS globules on the walls of nanotubes, coating them partially, thereby limiting the interaction between the nanotubes in the polymer matrix. This results in a charge transport governed mainly by small polarons in the conducting polymer despite the presence of metallic MWNTs. At T > 4 K, hopping of the charge carriers following one-dimensional variable range hopping is evident which also gives rise to a positive magnetoresistance (MR) with an enhanced localization length (~5 nm) due to the presence of MWNTs. However, at T < 4 K, the observation of an unconventional positive temperature coefficient of resistivity is attributed to small polaron tunnelling. The exceptionally large negative MR observed in this temperature regime is conjectured to be due to the presence of quasi-1D MWNTs that can aid in lowering the tunnelling barrier across the nanotube-polymer boundary resulting in large delocalization.

Choudhury, Paramita Kar; Ramaprabhu, S.; Ramesh, K. P.; Menon, Reghu

2011-07-01

 
 
 
 
381

Correlated conformation and charge transport in multiwall carbon nanotube-conducting polymer nanocomposites  

Energy Technology Data Exchange (ETDEWEB)

The strikingly different charge transport behaviours in nanocomposites of multiwall carbon nanotubes (MWNTs) and conducting polymer polyethylenedioxythiophene-polystyrene-sulfonic-acid (PEDOT-PSS) at low temperatures are explained by probing their conformational properties using small-angle x-ray scattering (SAXS). The SAXS studies indicate the assembly of elongated PEDOT-PSS globules on the walls of nanotubes, coating them partially, thereby limiting the interaction between the nanotubes in the polymer matrix. This results in a charge transport governed mainly by small polarons in the conducting polymer despite the presence of metallic MWNTs. At T > 4 K, hopping of the charge carriers following one-dimensional variable range hopping is evident which also gives rise to a positive magnetoresistance (MR) with an enhanced localization length ({approx}5 nm) due to the presence of MWNTs. However, at T < 4 K, the observation of an unconventional positive temperature coefficient of resistivity is attributed to small polaron tunnelling. The exceptionally large negative MR observed in this temperature regime is conjectured to be due to the presence of quasi-1D MWNTs that can aid in lowering the tunnelling barrier across the nanotube-polymer boundary resulting in large delocalization.

Kar Choudhury, Paramita; Ramesh, K P; Menon, Reghu [Department of Physics, Indian Institute of Science, Bangalore 560012 (India); Ramaprabhu, S, E-mail: paramita.karchoudhury@gmail.com [Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India)

2011-07-06

382

Correlated conformation and charge transport in multiwall carbon nanotube-conducting polymer nanocomposites  

International Nuclear Information System (INIS)

The strikingly different charge transport behaviours in nanocomposites of multiwall carbon nanotubes (MWNTs) and conducting polymer polyethylenedioxythiophene-polystyrene-sulfonic-acid (PEDOT-PSS) at low temperatures are explained by probing their conformational properties using small-angle x-ray scattering (SAXS). The SAXS studies indicate the assembly of elongated PEDOT-PSS globules on the walls of nanotubes, coating them partially, thereby limiting the interaction between the nanotubes in the polymer matrix. This results in a charge transport governed mainly by small polarons in the conducting polymer despite the presence of metallic MWNTs. At T > 4 K, hopping of the charge carriers following one-dimensional variable range hopping is evident which also gives rise to a positive magnetoresistance (MR) with an enhanced localization length (?5 nm) due to the presence of MWNTs. However, at T < 4 K, the observation of an unconventional positive temperature coefficient of resistivity is attributed to small polaron tunnelling. The exceptionally large negative MR observed in this temperature regime is conjectured to be due to the presence of quasi-1D MWNTs that can aid in lowering the tunnelling barrier across the nanotube-polymer boundary resulting in large delocalization.

383

Correlated conformation and charge transport in multiwall carbon nanotube-conducting polymer nanocomposites.  

Science.gov (United States)

The strikingly different charge transport behaviours in nanocomposites of multiwall carbon nanotubes (MWNTs) and conducting polymer polyethylenedioxythiophene-polystyrene-sulfonic-acid (PEDOT-PSS) at low temperatures are explained by probing their conformational properties using small-angle x-ray scattering (SAXS). The SAXS studies indicate the assembly of elongated PEDOT-PSS globules on the walls of nanotubes, coating them partially, thereby limiting the interaction between the nanotubes in the polymer matrix. This results in a charge transport governed mainly by small polarons in the conducting polymer despite the presence of metallic MWNTs. At T > 4 K, hopping of the charge carriers following one-dimensional variable range hopping is evident which also gives rise to a positive magnetoresistance (MR) with an enhanced localization length (?5 nm) due to the presence of MWNTs. However, at T tunnelling. The exceptionally large negative MR observed in this temperature regime is conjectured to be due to the presence of quasi-1D MWNTs that can aid in lowering the tunnelling barrier across the nanotube-polymer boundary resulting in large delocalization. PMID:21673397

Choudhury, Paramita Kar; Ramaprabhu, S; Ramesh, K P; Menon, Reghu

2011-07-01

384

Molecular junctions of self-assembled monolayers with conducting polymer contacts.  

Science.gov (United States)

We present a method to fabricate individually addressable junctions of self-assembled monolayers (SAMs) that builds on previous studies which have shown that soft conductive polymer top contacts virtually eliminate shorts through the SAMs. We demonstrate devices with nanoscale lateral dimensions, representing an order of magnitude reduction in device area, with high yield and relatively low device-to-device variation, improving several features of previous soft contact devices. The devices are formed in pores in an inorganic dielectric layer with features defined by e-beam lithography and dry etching. We replace the aqueous PEDOT:PSS conductive polymer used in prior devices with Aedotron P, a low-viscosity, amphiphilic polymer, allowing incorporation of self-assembled monolayers with either hydrophobic or hydrophilic termination with the same junction geometry and materials. We demonstrate the adaptability of this new design by presenting transport measurements on SAMs composed of alkanethiols with methyl, thiol, carboxyl, and azide terminations. We establish that the observed room-temperature tunnel barrier is primarily a function of monolayer thickness, independent of the terminal group's hydrophilicity. Finally, we investigate the temperature dependence of transport and show that the low-temperature behavior is based on the energy distribution of sites from which carriers can tunnel between the polymer and gold contacts, as described by a model of variable-range hopping transport in a disordered conductor. PMID:23035989

Neuhausen, Alexander B; Hosseini, Ali; Sulpizio, Joseph A; Chidsey, Christopher E D; Goldhaber-Gordon, David

2012-11-27

385

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

DEFF Research Database (Denmark)

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