WorldWideScience
1

White-light sources based on composites of GaN nanocrystals with conducting polymers and nanophosphors  

Science.gov (United States)

Optical properties of nanocomposites of GaN nanocrystals, 2-4 nm in diameter, with conjugated polymers such as poly(2-methoxy,5-(2-ethylhexoxy)-1,4-phenylenevinylene (MEHPPV) as well as with phosphors nanoparticles have been investigated for use as white light sources. Photoluminescence spectra of the nanocomposites with different weight ratios of the two components are reported. Weak electroluminescence has been observed in the case of MEHPPV-GaN nanocomposites. The GaN-nanophosphor composites exhibit a high quality white light with good CIE coordinates along with an excellent colour rendering index.

Chitara, Basant; Venkataprasad Bhat, S.; Vivekchand, S. R. C.; Gomathi, A.; Rao, C. N. R.

2008-09-01

2

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

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

2014-06-17

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

Non-volatile memory device using a polymer modified nanocrystal  

Energy Technology Data Exchange (ETDEWEB)

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

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

2011-11-25

6

The hydrodynamic size of polymer stabilized nanocrystals  

International Nuclear Information System (INIS)

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

7

The hydrodynamic size of polymer stabilized nanocrystals  

Energy Technology Data Exchange (ETDEWEB)

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.

Krueger, Karl M; Al-Somali, Ali M; Mejia, Michelle; Colvin, Vicki L [Department of Chemistry, Rice University, MS-60 6100 Main Street, Houston, TX 77005 (United States)

2007-11-28

8

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

9

Charge transport in hybrid films of ?-conjugated polymers and semiconductor nanocrystals  

OpenAIRE

The aim of this work is the study of photogenerated charge transport in hybrid films composed of ?-conjugated polymers and of semiconductor nanocrystals, designed for applications in optoelectronics. Chemical synthesis provides gram-scale samples of CdSe nanocrystals, of low polydispersity and con- trolled shapes (spherical, branched). In order to enhance their conductivity, the surface ligands of CdSe nanocrystals (stearic acid, oleylamine) are exchanged by smaller molecules, namely pyridin...

Couderc, Elsa

2012-01-01

10

Ligand engineering in hybrid polymer:nanocrystal solar cells  

Directory of Open Access Journals (Sweden)

Full Text Available Blends of semiconducting polymers and inorganic semiconductor nanocrystals are receiving renewed interest as a type of inexpensive, solution-processed third generation solar cell. In these hybrid bulk heterojunctions (BHJs, the interface between the disparate organic and inorganic phases is a dominating factor in the overall performance of the resulting devices. Paramount to this interface is the ligand landscape on the nanocrystal surface, which as a result of the inherently large surface area to volume ratio of the nanocrystals, has a significant spatial and electronic influence on the boundary between the donor polymer and acceptor nanocrystal. We have investigated the importance of this three-part polymer/ligand/nanocrystal interface by studying the ligand effects in hybrid BHJ solar cells. In this article, we highlight the major research advances and the state-of-the-art in hybrid BHJ solar cells with respect to ligand engineering, as well as outline future research avenues deemed necessary for continued technological advancement.

Matthew J. Greaney

2015-01-01

11

Polymer ligand exchange to control stabilization and compatibilization of nanocrystals.  

Science.gov (United States)

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

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

2014-06-24

12

Conductive Polymer Composites  

OpenAIRE

In recent years, nanotechnologies have led to the production of materials with new and sometimes unexpected qualities through the manipulation of nanoscale components. This research aimed primarily to the study of the correlation between hierarchical structures of hybrid organic-inorganic materials such as conductive polymer composites (CPCs). Using a bottom-up methodology, we could synthesize a wide range of inorganic nanometric materials with a high degree of homogeneity and purity, ...

Pierini, Filippo

2013-01-01

13

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

14

Conducting Polymers: Emerging Commercial Materials .  

Directory of Open Access Journals (Sweden)

Full Text Available Conducting polymers are materials of recent origin. They are obtained by polymerisation of simple organic monomers and doping with electron acceptor or donor species and show conductivity ranging from that of a semiconductor to that of metal. These materials are now available with unique electronic and optical properties of metals and semiconductors in combination with the attractive mechanical and processable advantages of polymers. The field has progressed to a level of maturity consistent with a new set of opportunities to develop Wide range of applications based upon conducting polymers as materials for industrial products.Examples include: static charge dissipation, EMI shielding, flexible light emitting diodes, transparent electrodes, batteries, gas sensors, gas separators, etc. Many of the conducting polymers and devices based on them are now available commercially.

N. Kumar

2013-04-01

15

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

16

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

17

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

International Nuclear Information System (INIS)

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

18

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2009-11-04

19

Intermolecular adhesion in conducting polymers  

CERN Document Server

We analyze the interaction of two conducting, charged polymer chains in solution using a minimal model for their electronic degrees of freedom. We show that a crossing of the two chains in which the polymers pass within Angstroms of each other leads to a decrease of the electronic energy of the combined system that is significantly larger than the thermal energy and thus promotes interchain aggregation. We consider the competition of this attractive interaction with the screened electrostatic repulsion and thereby propose a phase diagram for such polymers in solution; depending on the charge density and persistence length of the chains, the polymers may be unbound, bound in loose, braid-like structures, or tightly bound in a parallel configuration.

Schmit, J D; Schmit, Jeremy D.; Levine, Alex J.

2004-01-01

20

Electrically conductive polymer concrete overlays  

Science.gov (United States)

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

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

1984-08-01

21

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

22

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

International Nuclear Information System (INIS)

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

23

Conducting polymers by ion implantation  

Science.gov (United States)

An electrically conductive surface can be created by using the ion implantation process on nonconducting polymeric sheet. The resulting conductivity was measured and correlated to ion beam parameters, such as ion species, dose, and energy. Additionally, a reaction model, in both physical and chemical terms, was proposed, which can assist in understanding of the underlying mechanisms during the ion implantation of polymers. The surface microscopic structure of the ion-implanted polymer specimens was evaluated by X-ray photoelectron spectroscopy (XPS), electron spin resonance (ESR), Rutherford backscattering spectroscopy (RBS), and infrared spectroscopy (IR). The experimental results indicated that the ion bombardment process leads to a carbon-enriched material in a manner akin to the carbonization of organic films observed upon pyrolytic processing.

Loh, I. H.; Oliver, R. W.; Sioshansi, P.

1988-09-01

24

Optical Gain from InAs Nanocrystal Quantum Dots in a Polymer Matrix  

OpenAIRE

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

Chen, Gang; Rapaport, Ronen; Fuchs, Dan; Vilan, Sahar; Aharoni, Assaf; Banin, Uri

2005-01-01

25

Comparing proton conductivity of polymer electrolytes by percent conducting volume  

Energy Technology Data Exchange (ETDEWEB)

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

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

2009-01-01

26

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)

27

Electrophysical Properties of Thermally Conductive Polymer Materials  

Science.gov (United States)

Results of studies on basic electrophysical properties of new thermally conductive polymer materials based on low-density polyethylene and the random copolymer of propylene and ethylene are presented. It has been shown that modifying the polymer matrix with carbon-containing fillers allows thermally conductive polymer materials with both low and high electrical conductivity to be developed.

Lebedev, S. M.; Gefle, O. S.; Dneprovskii, S. N.; Amitov, E. T.

2015-02-01

28

ac conductivity of emeraldine polymer  

Science.gov (United States)

An experimental study of the temperature- (T-) dependent dc and audio-frequency conductivity (?) as a function of protonation level (0.0Cole-Cole analysis shows the presence of primarily a single thermally activated relaxation process in these materials with a dispersion in relaxation rates. These results are discussed in the context of models for dc and ac transport in polymers, with results supporting hopping of charge among positively charged polaron and bipolaron or neutral defect (polaron) states in the emeraldine polymer. A simple analysis yields estimates of 3.7×10-3 bipolarons per polaron in the x=0 system, increasing with protonation to 7.9×10-2 for x=0.08.

Zuo, F.; Angelopoulos, M.; MacDiarmid, A. G.; Epstein, A. J.

1989-02-01

29

Enhanced Semiconductor Nanocrystal Conductance via Solution Grown Contacts  

Energy Technology Data Exchange (ETDEWEB)

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

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

2009-08-19

30

A merocyanine-based conductive polymer  

OpenAIRE

We report the first example of a conducting polymer with a merocyanine incorporated into the polymer backbone by electropolymerisation of a spiropyran moiety covalently linked between two alkoxythiophene units. Utilising the known metal coordination capabilities of merocyanines, introduction of cobalt ions into the electropolymerisation led to an enhancement of the conductivity, morphology and optical properties of the polymer films.

Wagner, Klaudia; Zanoni, Michele; Elliott, Anastasia B. S.; Wagner, Pawel; Byrne, Robert; Florea, Larisa; Diamond, Dermot; Gordon, Keith; Wallace, Gordon; Officer, David

2013-01-01

31

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

32

Direct writing of conducting polymers.  

Science.gov (United States)

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

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

2013-08-01

33

Application potential of conducting polymers  

International Nuclear Information System (INIS)

Intrinsically conducting polymers (ICPs) represent a special class of weak materials with electronic and ionic conductivity. Chemical and physical properties are dependent on their redox state. These properties allow a wide application as functional coatings. At constant film conditions, ICPs can be used in the dry or wet state due to their electronic conductivity, due to their porous structure or due to their processibility in microstructuring processes. The production of conducting electrodes on electrolyte condensers and the through hole plating of printed circuit boards (PCBs) represent typical examples. In sensors and membranes, the pore structure is applied. The application of variable properties, however, is of much greater interest. It is based on the change of charge, electronic states, chemical composition and mechanical properties during the reversible redox process. In contrast to original expectations, small intercalation factors hinder the application in batteries or supercaps. For OLEDs, however, most problems seem to be solved. Application of switching hydrophilic/hydrophobic properties is proved for offset printing but not yet applied. Usually, the anodic doping is investigated. The correspondent cathodic doping opens additional applications. The application of ICPs in functional coatings requires special properties such as fast response (e.g. in ms), stability for 103 cycles for batteries and 106 switches for displays, and a constant potential of dis displays, and a constant potential of discharge for batteries. Moreover, the stability against corrosion, overoxidation and delamination has to be guaranteed. Chemical modification of the monomer allows wide variations of properties, but economic requirements limit the price of the monomer and, thereby, the thickness or quality of the coating

34

Hybrid conducting polymer-silver composites.  

Czech Academy of Sciences Publication Activity Database

Blacksburg : Virginia Tech, 2012. T104. [World Polymer Congress - MACRO 2012. 24.06.2012-29.06.2012, Blacksburg] R&D Projects: GA AV ?R IAA400500905 Institutional research plan: CEZ:AV0Z40500505 Institutional support: RVO:61389013 Keywords : conducting polymer * polyaniline * polymer-metal composite Subject RIV: CD - Macromolecular Chemistry

Stejskal, Jaroslav; Bober, Patrycja; Trchová, Miroslava; Prokeš, J.; Omastová, M.

35

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

36

Conducting Polymers for Neutron Detection  

International Nuclear Information System (INIS)

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

37

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

38

Prospects of conducting polymers in biosensors  

International Nuclear Information System (INIS)

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

39

A Platform for Functional Conductive Polymers  

DEFF Research Database (Denmark)

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

Daugaard, Anders Egede; Hoffmann, Christian

40

“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

41

Conductivity studies on solid polymer electrolytes  

OpenAIRE

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

42

Conductivity studies on solid polymer electrolytes  

International Nuclear Information System (INIS)

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

43

Conductive polymer/superconductor bilayer structures  

International Nuclear Information System (INIS)

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

44

Conjugated polymers/semiconductor nanocrystals hybrid materials--preparation, electrical transport properties and applications.  

Science.gov (United States)

This critical review discusses specific preparation and characterization methods applied to hybrid materials consisting of ?-conjugated polymers (or oligomers) and semiconductor nanocrystals. These materials are of great importance in the quickly growing field of hybrid organic/inorganic electronics since they can serve as active components of photovoltaic cells, light emitting diodes, photodetectors and other devices. The electronic energy levels of the organic and inorganic components of the hybrid can be tuned individually and thin hybrid films can be processed using low cost solution based techniques. However, the interface between the hybrid components and the morphology of the hybrid directly influences the generation, separation and transport of charge carriers and those parameters are not easy to control. Therefore a large variety of different approaches for assembling the building blocks--conjugated polymers and semiconductor nanocrystals--has been developed. They range from their simple blending through various grafting procedures to methods exploiting specific non-covalent interactions between both components, induced by their tailor-made functionalization. In the first part of this review, we discuss the preparation of the building blocks (nanocrystals and polymers) and the strategies for their assembly into hybrid materials' thin films. In the second part, we focus on the charge carriers' generation and their transport within the hybrids. Finally, we summarize the performances of solar cells using conjugated polymer/semiconductor nanocrystals hybrids and give perspectives for future developments. PMID:21152569

Reiss, Peter; Couderc, Elsa; De Girolamo, Julia; Pron, Adam

2011-02-01

45

Chiral conductive polymers as spin filters.  

Science.gov (United States)

Chiral conducting polymer films are self-assembled on ferromagnetic materials and exhibit an efficient spin filtering at room temperature. In addition, the present system displays asymmetric magnetoresistance with respect to zero magnetic field. PMID:25619708

Mondal, Prakash Chandra; Kantor-Uriel, Nirit; Mathew, Shinto P; Tassinari, Francesco; Fontanesi, Claudio; Naaman, Ron

2015-03-01

46

Understanding Ionic Conductivity in Crystalline Polymer Electrolytes  

OpenAIRE

Polymer electrolytes are widely used as ion transport media in vital applications such as energy storage devices and electrochemical displays. To further develop these materials, it is important to understand their ionic conductivity mechanisms. It has long been thought that ionic conduction in a polymer electrolyte occurs in the amorphous phase, while the crystalline phase is insulating. However, this picture has recently been challenged by the discovery of the crystalline system LiXF6?PEO...

Brandell, Daniel

2005-01-01

47

Conductive polymer switch for controlling superconductivity  

International Nuclear Information System (INIS)

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

48

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

49

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

50

Surface passivation in CdSe nanocrystal-polymer films revealed by ultrafast excitation relaxation dynamics  

International Nuclear Information System (INIS)

The photoluminescence efficiencies and excitation relaxation dynamics in CdSe nanocrystals (NC) passivated with tri-n-octylphosphine oxide and embedded in two different polymer matrixes, poly(styrene) (PS) and poly(butylmethacrylate) (PBMA), are compared. Femtosecond pump-probe absorption spectroscopy is used to clarify the influence of various transparent polymer matrixes on the electronic properties and excitation relaxation dynamics of quantum confined CdSe semiconductor nanocrystals of 5.0 nm diameter. The fluorescence intensity is reported to be ?10 times higher for the NC-PS sample compared to the NC-PBMA film. This striking difference in fluorescence yield is shown to be related to markedly different rates of nonradiative excitation relaxation in the two samples, and is attributed directly to a role played by the polymer host. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

51

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

52

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

International Nuclear Information System (INIS)

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

53

Hybrid bulk heterojunction solar cells based on low band gap polymers and CdSe nanocrystals  

Science.gov (United States)

Solar energy converters based on organic semiconductors are inexpensive, can be layered onto flexible surfaces, and show great promise for photovoltaics. In bulk heterojunction polymer solar cells, charges are separated at the interface of two materials, an electron donor and an electron acceptor. Typically, only the donor effectively absorbs light. Therefore, the use of an acceptor with a wide absorption spectrum and high extinction coefficient and charge mobility should increase the efficiency of bulk heterojunction polymer solar cells. Semiconductor nanocrystals (quantum dots and rods) are good candidate acceptors for these solar cells. Recently, most progress in the development of bulk heterojunction polymer solar cells was achieved using PCBM, a traditional fullerene acceptor, and two low band gap polymers, poly[N- 9'-heptadecanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)] (PCDTBT) and poly4,8-bis[(2- ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b] thiophenediyl (PTB7). Therefore, the possibility of combining these polymers with semiconductor nanocrystals deserves consideration. Here, we present the first comparison of solar cells based on PCDTBT and PTB7 where CdSe quantum dots serve as acceptors. We have found that PTB7-based cells are more efficient than PCDTBT-based ones. The efficiency also strongly depends on the nanocrystal size. An increase in the QD diameter from 5 to 10 nm causes a more than fourfold increase in the cell efficiency. This is determined by the relationship between the nanoparticle size and energy spectrum, its pattern clearly demonstrating how the mutual positions of the donor and acceptor levels affect the solar cell efficiency. These results will help to develop novel, improved nanohybrid components of solar cells based on organic semiconductors and semiconductor nanocrystals.

Dayneko, Sergey; Tameev, Alexey; Tedoradze, Marine; Martynov, Igor; Linkov, Pavel; Samokhvalov, Pavel; Nabiev, Igor; Chistyakov, Alexander

2014-03-01

54

Conducting polymers: Synthesis and industrial applications  

Energy Technology Data Exchange (ETDEWEB)

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

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

1997-04-01

55

Conductivity of carbon nanotube polymer composites  

Energy Technology Data Exchange (ETDEWEB)

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

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

2006-11-20

56

Flash welding of conducting polymer nanofibres.  

Science.gov (United States)

The absorption of light by a material generates heat through non-radiative energy dissipation and exothermic photochemical reactions. In nanostructured materials, the heat generated through photothermal processes will be confined within the individual nanostructures when heat transfer to neighbouring nanostructures and the environment is slow. This leads to unprecedented photothermal effects that cannot be observed in bulk materials, especially when a strong, pulsed light source is used. Here we demonstrate an enhanced photothermal phenomenon with conducting polymer nanofibres in which a camera flash causes instantaneous welding. Under flash irradiation, polyaniline nanofibres 'melt' to form a smooth and continuous film from an originally random network of nanofibres. This photothermal effect can be used to form asymmetric nanofibre films, to melt-blend polymer-polymer nanocomposites rapidly and to photo-pattern polymer nanofibre films. PMID:15502832

Huang, Jiaxing; Kaner, Richard B

2004-11-01

57

Exciton Dynamics in Alternative Solar Cell Materials: Polymers, Nanocrystals, and Small Molecules  

Science.gov (United States)

To keep fossil fuel usage in 2040 even with 2010 usage, 50% of global energy will need to come from alternative sources such as solar cells. While the photovoltaic market is currently dominated by crystalline silicon, there are many low-cost solar cell materials such as conjugated polymers, semiconductor nanocrystals, and organic small molecules which could compete with fossil fuels. To create cost-competitive devices, understanding the excited state dynamics of these materials is necessary. The first section of this thesis looks at aggregation in poly(3-hexylthiophene) (P3HT) which is commonly used in organic photovoltaics. The amount of aggregation in P3HT thin films was controlled by using a mixture of regioregular and regiorandom P3HT. Even with few aggregates present, excited states were found to transfer from amorphous to aggregate domains in P3HT aggregation, a triblock consisting of two P3HT chains with a coil polymer between them was investigated. By changing solvents, aggregation was induced in a stable and reversible manner allowing for spectroscopic studies of P3HT aggregates in solution. The polarity of the solvent was adjusted, and no change in excited state dynamics was observed implying the excited state has little charge-transfer character. Next, the conduction band density of states for copper zinc tin sulfide nanocrystals (CZTS NCs) was measured using pump-probe spectroscopy and found to be in agreement with theoretical results. The density of states shifted and dilated for smaller NCs indicative of quantum confinement. The excited state lifetime was found to be short (<20 ps) and independent of NC size which could limit the efficiency of CZTS photovoltaic devices. Finally, triplet-triplet annihilation (TTA) was studied in platinum octaethylporphyrin (PtOEP) thin films. By analyzing pump-probe spectra, the product of TTA in PtOEP thin films was assigned to a long-lived metal-centered state. To elucidate the mechanism of TTA, the annihilation dynamics were modeled using second order kinetics as well as Forster and Dexter energy transfer. Dexter energy transfer provided the best fits and the most reasonable fitting parameters.

Pundsack, Thomas J.

58

Conducting polymer actuators as engineering materials  

Science.gov (United States)

Conducting polymer actuators were first proposed more than ten years ago. Reported performance has improved dramatically, particularly in the past few years, due to changes in synthesis methods, better characterization and an understanding of the underlying mechanisms. These actuators are able to displace large loads (up to 100x greater than mammalian skeletal muscle), with moderate displacements (typically 2 %), and with power to mass ratios similar to that of muscle, while powered using potentials of no more than a few volts. Unlike electric motors and muscle, these actuators exhibit a catch state, enabling them to maintain force without consuming energy. Despite the impressive performance, commercial applications are at an early stage. One reason is the need to carefully consider the details of the actuator construction, including the thickness and surface area of the polymer, the electrolyte conductivity and geometry, the counter electrode spacing, the shape of the input voltage and the means of electrical contact to the polymer, in designing effective actuators. A set of design guidelines is presented that assist the device designer in determining the optimum actuator configuration. These are derived from extensive characterization and modeling of hexafluorophosphate-doped polypyrrole actuators. The set of design tools helps transform conducting polymer actuators into engineering materials that can be selected and designed for particular applications based on rational criteria. Most of the underlying physical principles used in determining these rules also underlie other conducting polymer actuators, polymer devices such as electrochromic displays, supercapacitors and batteries, carbon nanotube actuators, and electrochemically driven devices that involve volumetric charge storage.

Madden, John D.; Madden, Peter G.; Hunter, Ian W.

2002-07-01

59

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

60

Strategies for interfacing inorganic nanocrystals with biological systems based on polymer-coating.  

Science.gov (United States)

Interfacing inorganic nanoparticles and biological systems with the aim of developing novel imaging and sensing platforms has generated great interest and much activity. However, the effectiveness of this approach hinges on the ability of the surface ligands to promote water-dispersion of the nanoparticles with long term colloidal stability in buffer media. These surface ligands protect the nanostructures from the harsh biological environment, while allowing coupling to target molecules, which can be biological in nature (e.g., proteins and peptides) or exhibit specific photo-physical characteristics (e.g., a dye or a redox-active molecule). Amphiphilic block polymers have provided researchers with versatile molecular platforms with tunable size, composition and chemical properties. Hence, several groups have developed a wide range of polymers as ligands or micelle capsules to promote the transfer of a variety of inorganic nanomaterials to buffer media (including magnetic nanoparticles and semiconductor nanocrystals) and render them biocompatible. In this review, we first summarize the established synthetic routes to grow high quality nanocrystals of semiconductors, metals and metal oxides. We then provide a critical evaluation of the recent developments in the design, optimization and use of various amphiphilic copolymers to surface functionalize the above nanocrystals, along with the strategies used to conjugate them to target biomolecules. We finally conclude by providing a summary of the most promising applications of these polymer-coated inorganic platforms in sensor design, and imaging of cells and tissues. PMID:25029116

Palui, Goutam; Aldeek, Fadi; Wang, Wentao; Mattoussi, Hedi

2015-01-01

61

Intrinsically conductive polymer thin film piezoresistors  

DEFF Research Database (Denmark)

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

Lillemose, Michael; Spieser, Martin

2008-01-01

62

Hydrothermal microemulsion synthesis of oxidatively stable cobalt nanocrystals encapsulated in surfactant/polymer complex shells.  

Science.gov (United States)

Air-stable magnetic cobalt nanocrystals have been conveniently prepared via a reverse micellar synthesis, followed by a hydrothermal treatment. The synthesis was carried out by first mixing an aqueous solution containing cobalt chloride and poly(sodium 4-styrenesulfonate) (PSS) with an organic mixture containing cetyltrimethylammonium bromide (CTAB) to form reverse micelles, followed by reducing cobalt ions with sodium borohydride. The resultant nanoparticles were then undergone a hydrothermal treatment at 165 degrees C for 8 h to generate well-dispersed CTAB/PSS-encapsulated cobalt nanocrystals with an average diameter of 3.5 +/- 0.5 nm. The nanoparticles were highly crystalline with a hexagonal close-packed crystal phase. The presence of CTAB/PSS complex coatings was identified by FT-IR and UV-vis spectroscopies as well as thermogravimetry analyses. The nanocrystals exhibited superparamagnetic property at room temperature with a saturation magnetization (M(s)) of 95 emu/g. The magnetization could be largely preserved after storage at room temperature for 4 months as the M(s) value only slightly decreased to 88 emu/g (measured at 300 K). Thus, the polymer encapsulation could not only improve thermal stability of the micelles for the growth and nucleation of Co atoms but also protect the resulting cobalt nanocrystals from oxidation through forming an oxygen impermeable sheath. PMID:20337480

Zhang, Xian-Hua; Ho, Kin Man; Wu, Ai-Hua; Wong, Kin Hung; Li, Pei

2010-04-20

63

Conjugated Polymer and Luminescent Nanocrystals for Ink-Jet Printing  

Science.gov (United States)

Nanocomposite solutions formed of Poly [(9,9-diesilfluorene)-(2,7 diyl)-alt-(2,5-dimetil-1,4-phenilene)] and highly luminescent nanocrystals of CdSe coated with a shell of ZnS (CdSe@ZnS) with different size have been obtained by using a common solvent and characterized by means of absorption and emission spectroscopy. Viscosity has been investigated, in order to prove the suitability of the inks for the printing processing. The homogeneous nanocomposites have been precisely dispensed by ink-jet printing, using drop-on-demand mode onto glass substrates. The deposited micro-scale pixels have been morphologically characterized by means of fluorescence microscopy, 3D profilometry and Atomic Force Microscopy (AFM). The results demonstrate that the spectroscopical properties of the components have been effectively conveyed to the final nanocomposites, retaining the size dependent feature of the inorganic moiety, and providing a suitable ink with for fabricating reproducible microstructures.

Binetti, E.; Ingrosso, C.; Striccoli, M.; Cosma, P.; Agostiano, A.; Kim, J. Y.; Brugger, J.; Curri, M. L.

2010-06-01

64

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

65

Ion conducting organic/inorganic hybrid polymers  

Science.gov (United States)

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

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

2010-01-01

66

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

67

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

68

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

69

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

70

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.

71

Conducting Polymers and Their Hybrids as Organic Thermoelectric Materials  

Science.gov (United States)

Conducting polymers have received much attention recently as organic thermoelectric materials, because of such advantages as plentiful resources, easy synthesis, easy processing, low cost, low thermal conductivity, and easy fabrication of flexible, light, and printable devices with large area. Many reports on organic thermoelectric materials have recently been published. We have studied conducting polymers as organic thermoelectric materials since 1999. During these investigations, we found that the thermal conductivity of conducting polymers did not increase even though electrical conductivity increased; this was a major advantage of conducting polymers as organic thermoelectric materials. We also observed that molecular alignment was one of the most important factors for improvement of the thermoelectric performance of conducting polymers. Stretching of conducting polymers or their precursors was one of the most common techniques used to achieve good molecular alignment. Recently, alignment of the clusters of conducting polymers by treatment with solvents has been proposed as a means of achieving high electrical conductivity. Hybridization of conducting polymers with inorganic nanoparticles has also been found to improve thermoelectric performance. Here we present a brief history and discuss recent progress of research on conducting polymers as organic thermoelectric materials, and describe the techniques used to improve thermoelectric performance by treatment of conducting polymers with solvents and hybridization of conducting polymers with Bi2Te3 and gold nanoparticles.

Toshima, Naoki; Ichikawa, Shoko

2015-01-01

72

Structural investigations and processing of electronically and protonically conducting polymers  

OpenAIRE

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

Vilkman, Marja

2010-01-01

73

Synthesis of novel electrically conducting polymers: Potential conducting Langmuir-Blodgett films and conducting polymers on defined surfaces  

Science.gov (United States)

Based on previous results involving thiophene derived electrically conducting polymers in which it was shown that thiophene, 3-substituted thiophenes, furans, and certain oligomers of these compounds showed electrical conductivity after polymerization. The conductivity was in the order of up to 500 S/cm. In addition, these polymers showed conductivity without being doped and most of all they were practically inert toward ambient conditions. They even could be used in aqueous media. With these findings as a guide, a number of 3-long-chain-substituted thiophenes and 1-substituted-3-long-chain substituted pyrrols were synthesized as monomers for potential polymeric electrically conducting Langmuir-Blodgett films.

Zimmer, Hans

1993-01-01

74

Conductive polymers: chiral conductive polymers as spin filters (adv. Mater. 11/2015).  

Science.gov (United States)

Conductive organic polymers are used in organic-based light-emitting diodes (OLEDs). It is expected that by controlling the spin of the electrons that are injected from and into these devices, their energy efficiency will increase significantly. The work by C. Fontanesi, R. Naaman, and co-workers on page 1924 shows that the polymers themselves can serve as a spin filter, and this may allow the operation of spin-OLEDs without any magnetic component. PMID:25765616

Mondal, Prakash Chandra; Kantor-Uriel, Nirit; Mathew, Shinto P; Tassinari, Francesco; Fontanesi, Claudio; Naaman, Ron

2015-03-01

75

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

Science.gov (United States)

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

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

2014-05-01

76

Photophysical properties of fullerene-conducting polymer system  

Energy Technology Data Exchange (ETDEWEB)

Optical properties of conducting polymers such as absorption spectrum, photoluminescence, electroluminescence, photo-magnetic effect, photoconductivity, non-linear optical phenomena and their dynamics change drastically upon doping of small amount of fullerene. Electrical and optical characteristics of junctions based on conducting polymers and fullerenes are also anomalous. It should be mentioned that these unique photophysical properties and their dynamics are dependent on the molecular structure of conducting polymer (non-degenerated polymers such as polythiophene derivatives or degenerated polymers such as polyacetylene derivatives) and also on fullerenes (C{sub 60}, C{sub 70}). These novel results are discussed in terms of photoexcitation in both conducting polymers and fullerene, photoinduced excitons, solitons, polarons, also their transfers between conducting polymers and fullerene, capture of carriers by C{sub 60}, influence of C{sub 60} on inter-chain charge transport by taking into account the electronic energy states of conducting polymers and fullerenes. (orig.)

Akashi, K.Y.T. [Dept. of Electronic Engineering, Osaka Univ. (Japan); Morita, S. [Dept. of Electronic Engineering, Osaka Univ. (Japan); Yoshida, M. [Dept. of Electronic Engineering, Osaka Univ. (Japan); Hamaguchi, M. [Dept. of Electronic Engineering, Osaka Univ. (Japan); Tada, K. [Dept. of Electronic Engineering, Osaka Univ. (Japan); Fujii, A. [Dept. of Electronic Engineering, Osaka Univ. (Japan); Kawai, T. [Dept. of Electronic Engineering, Osaka Univ. (Japan); Uto, S. [Dept. of Electronic Engineering, Osaka Univ. (Japan); Ozaki, M. [Dept. of Electronic Engineering, Osaka Univ. (Japan); Onoda, M. [Dept. of Electronic Engineering, Osaka Univ. (Japan); Zakhidov, A.A. [Dept. of Electronic Engineering, Osaka Univ. (Japan)

1995-03-15

77

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 artificiathe 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.

78

FePt nanocrystals embedded in methylmethacrylate polymers  

International Nuclear Information System (INIS)

A simple, controlled and reproducible procedure is reported to obtain polymerized methylmethacrylate by embedding monodisperse Fe6Pt4 nanoparticles. The magnetic properties of the composite material can be controlled by the magnetic properties and the concentration (up to 0.3 wt%) of the starting nanoparticle dispersions. SQUID magnetometry measurements of FePt-doped methylmethacrylate polymers show superparamagnetic behavior at room temperature confirming the homogeneous particle distribution and the non-occurrence of agglomerates inside the polymeric matrix also observed by transmission electron microscopy. Even at the highest concentration the average particle distances are so large that no particle interactions play a role

79

Free volume and conductivity in polymer electrolytes  

International Nuclear Information System (INIS)

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

80

Characterizations of proton conducting polymer electrolytes for electrochemical capacitors  

International Nuclear Information System (INIS)

Solid polymer electrolytes containing phosphotungstic acid (PWA) and/or silicotungstic acid (SiWA) in polyvinyl alcohol (PVA) were investigated for their proton conductivities. Enhanced conductivity was obtained when mixing PWA and SiWA at equal ratio. This polymer electrolyte was found viable for electrochemical capacitors. Thermal and structural analyses were conducted with DSC, XRD, and FTIR. The polymer electrolyte exhibited a different structure and different thermal properties from its respective components. The polymer electrolyte retained its original Keggin structure but contained crystallized protonated water in the form of H5O2+. The protonated water may contribute to the proton conductivity of the polymer electrolyte.

81

Characterizations of proton conducting polymer electrolytes for electrochemical capacitors  

Energy Technology Data Exchange (ETDEWEB)

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

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

2010-12-15

82

Multi-stimulus-responsive shape-memory polymer nanocomposite network cross-linked by cellulose nanocrystals.  

Science.gov (United States)

In this study, we developed a thermoresponsive and water-responsive shape-memory polymer nanocomposite network by chemically cross-linking cellulose nanocrystals (CNCs) with polycaprolactone (PCL) and polyethylene glycol (PEG). The nanocomposite network was fully characterized, including the microstructure, cross-link density, water contact angle, water uptake, crystallinity, thermal properties, and static and dynamic mechanical properties. We found that the PEG[60]-PCL[40]-CNC[10] nanocomposite exhibited excellent thermo-induced and water-induced shape-memory effects in water at 37 °C (close to body temperature), and the introduction of CNC clearly improved the mechanical properties of the mixture of both PEG and PCL polymers with low molecular weights. In addition, Alamar blue assays based on osteoblasts indicated that the nanocomposites possessed good cytocompatibility. Therefore, this thermoresponsive and water-responsive shape-memory nanocomposite could be potentially developed into a new smart biomaterial. PMID:25647407

Liu, Ye; Li, Ying; Yang, Guang; Zheng, Xiaotong; Zhou, Shaobing

2015-02-25

83

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

Science.gov (United States)

In this work nanocomposites based on organic-capped semiconductor nanocrystals formed of a core of CdSe coated with a shell of ZnS (CdSe@ZnS), with different sizes, and a semiconducting conjugated polymer, namely poly[(9,9-dihexylfluoren-2,7-diyl)-alt- (2,5-dimethyl-1,4-phenylene)] (PF-DMB) have been investigated. The nanocomposites are prepared by mixing the pre-synthesized components in organic solvents, thereby assisting the dispersion of the organic-coated nano-objects in the polymer host. UV-vis steady state and time-resolved spectroscopy along with (photo)electrochemical techniques have been performed to characterize the obtained materials. The study shows that the embedded nanocrystals increase the PF-DMB stability against oxidation and, at the same time, extend the light harvesting capability to the visible spectral region, thus resulting in detectable photocurrent signals. The nanocomposites have been dispensed by means of a piezo-actuated inkjet system. Such inks present viscosity and surface tension properties well suited for stable and reliable drop-on-demand printing using an inkjet printer. The fabrication of arrays of single-color pixels made of the nanocomposites and micrometers in size has been performed. Confocal and atomic force microscopy have confirmed that inkjet-printed microstructures present the intrinsic emission properties of both the embedded nanocrystals and PF-DMB, resulting in a combined luminescence. Finally, the morphology of the printed pixels is influenced by the embedded nanofillers. PMID:22261314

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

2012-02-24

84

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)

85

Preparation of Electroconductive Paper by Deposition of Conducting Polymer  

OpenAIRE

The thesis describes an investigation into the interaction between the conducting polymer and cellulosic materials, and the preparation of electroconductive paper. The adsorption behavior of the conducting polymer onto cellulosic materials was characterized. Poly(3,4-ethylenedioxythiophene) doped with poly(4-styrene sulfonate) (PEDOT:PSS) was used as conducting polymer because of its attractive properties in terms of conductivity, water solubility, and environmental stability. The model subst...

Montibon, Elson

2009-01-01

86

DNA-sensors based on functionalized conducting polymers and quantum dots  

Science.gov (United States)

The availability of rapid and specific biosensors is of great importance for many areas of biomedical research and modern biotechnology. This includes a need for DNA sensors where the progress of molecular biology demands routine detection of minute concentrations of specific gene fragments. A promising alternative approach to traditional DNA essays utilizes novel smart materials, including conducting polymers and nanostructured materials such as quantum dots. We have constructed a number of DNA sensors based on smart materials that allow rapid one-step detection of unlabeled DNA fragments with high specificity. These sensors are based on functionalized conducting polymers derived from polypyrrole (PPy) and poly(p-phenylenevinylene) (PPV). PPy based sensors provide intrinsic electrical readout via cyclic voltammetry and electrochemical impedance spectroscopy. The performance of these sensors is compared to a novel self-assembled monolayer-PNA construct on a gold electrode. Characterization of the novel PNA based sensor shows that it has comparable performance to the PPy based sensors and can also be read out effectively using AC cyclic voltammetry. Complementary to such solid substrate sensors we have developed a novel optical DNA essay based on a new PPV derived cationic conducting polymer. DNA detection in this essay results from sample dependent fluorescence resonance energy transfer changes between the cationic conducting polymer and Cy3 labeled probe oligonucleotides. As an alternative to such fluorochrome based sensors we discuss the use of inorganic nanocrystals ('quantum dots') and present data from water soluble CdTe quantum dots synthesized in an aqueous environment.

Kjällman, Tanja; Peng, Hui; Travas-Sejdic, Jadranka; Soeller, Christian

2007-12-01

87

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

88

Polypeptide-guided assembly of conducting polymer nanocomposites  

OpenAIRE

A strategy for fabrication of electroactive nanocomposites with nanoscale organization, based on self-assembly, is reported. Gold nanoparticles are assembled by a polypeptide folding-dependent bridging. The polypeptides are further utilized to recruit and associate with a water soluble conducting polymer. The polymer is homogenously incorporated into the nanocomposite, forming conducting pathways which make the composite material highly conducting.

Hamedi, Mahiar; Wigenius, Jens; Tai, Feng-i; Bjo?rk, Per; Aili, Daniel

2010-01-01

89

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

90

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

Science.gov (United States)

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

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

2013-06-25

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

Mesoscopic modelling of charge evolution in conducting polymers  

OpenAIRE

We address here some of the issues relating to conducting polymer based devices. We examine the effects of polymer disorder on charge injection, transport, trapping and recombination in light-emitting diodes (LEDs) using a mesoscopic model which includes specific realizations of the electroluminescent polymer network. A key point of this model is to consider both the intermolecular and the interdomain charge carrier transport which are strongly influenced by structural polymer disorder. Simul...

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

2000-01-01

93

Gradiently anisotropic conducting and magnetic polymer composites  

OpenAIRE

The character of the local electric resistance variations of film polymer composites on the basis of polyvinyl alcohol with graphite powder on the one hand and the magnetic susceptibility of the same polymer with nickel nano-particles on the other hand has been studied. It has been established that the changes of these parameters essentially depends on both initial shape of the films and on the direction of their orientation. It is concluded that the films of gradiently anisotropic polymer co...

Aneli, Jimsher; Nadareishvili, Levan; Mamniashvili, Grigor; Akhalkatsi, Anatoli; Zaikov, Gennady

2012-01-01

94

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

95

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

96

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)

97

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

98

Anion-conducting polymer, composition, and membrane  

Energy Technology Data Exchange (ETDEWEB)

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

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

2009-09-01

99

Anion-conducting polymer, composition, and membrane  

Energy Technology Data Exchange (ETDEWEB)

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

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

2010-12-07

100

Anion-Conducting Polymer, Composition, and Membrane  

Energy Technology Data Exchange (ETDEWEB)

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

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

2008-10-21

101

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

102

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)

103

Analysis of solvent residuals in thin films of conducting polymers  

International Nuclear Information System (INIS)

Since conducting polymers show widespread application possibilities, e.g. in organic solar cells and organic field effect transistors, it is a serious concern to investigate long-time stability and aging. Aging can be enhanced due to remaining solvent embedded in the polymer matrix of thin films. Remaining solvent affects the mobility of the polymers and results in an ongoing change in the microstructure, which is accompanied by changes in the electrical performance. We investigated the remaining solvent in thin conducting polymer films with neutron reflectivity, utilising the contrast between protonated and deuterated solvents. In addition, we report surface analysis of different polymer blends based on versatile novel conducting polymers using atomic force microscopy. In these films a spatial resolved analysis concerning the solvent content is obtained with STXM measurements.

104

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

105

On the origin of mesoscopic inhomogeneity of conducting polymers.  

Science.gov (United States)

The mesoscopic inhomogeneity of conducting polymer films obtained by electropolymerization and spin-coating was studied using Kelvin probe force microscopy (KFM) and current-sensing atomic-force microscopy (CS-AFM). A well-pronounced correlation was established between the polymer morphology, on the one hand, and its local work function (which is related to the polymer oxidation degree) as well as polymer conductivity, on the other. The most conducting regions were associated with the tops of the polymer grains and showed Ohmic behavior. They were surrounded first by semiconducting and then by insulating polymer. The conductivity of the grain periphery could be lower by as much as 2 orders of magnitude. The grain cores also showed consistently higher values of the local work function as compared to the grain periphery. This fact suggested that the grain cores were more oxidized and/or more ordered as compared to the grain periphery, which is in good agreement with the local conductivity data. More uniform morphology corresponded to less variability in the other properties of the polymer. A model is proposed that relates the observed inhomogeneity to preferential deposition of polymer molecules with higher molecular weight at the early stages of the polymer phase formation. The polymer deposition in either electropolymerization or various solution-casting techniques involves the nucleation of a new phase from a solution containing polymer fractions of different molecular weights. The driving force of the nucleation process depends on the solubility of the polymer fractions, which decreases with an increase in the molecular weight. This gives rise to preferential deposition of more crystalline, higher molecular weight polymer at the early stages of the polymer deposition to form the cores of the polymer grains. The fractions with lower molecular weights are deposited later and form less ordered/less conducting grain periphery. On the basis of this model, we conclude that, to ensure the formation of materials with low inhomogeneity and high quality, one should use the starting polymer with as narrow molecular weight distribution as possible. Yet another possibility is to use solvents which would reduce the differences in the solubilities of polymer fractions with different molecular weight. PMID:17637051

O'Neil, Kevin D; Shaw, Bryan; Semenikhin, Oleg A

2007-08-01

106

Anisotropic polymer composites synthesized by immobilizing cellulose nanocrystal suspensions specifically oriented under magnetic fields.  

Science.gov (United States)

Novel polymer composites reinforced with an oriented cellulose nanocrystal (CNC) assembly were prepared from suspensions of CNC in aqueous 2-hydroxyethyl methacrylate (HEMA) via magnetic field application to the suspensions followed by polymerization treatment. The starting suspensions used at ?6 wt % CNC separated into an upper isotropic phase and a lower anisotropic (chiral nematic) one in the course of quiescent standing. A static or rotational magnetic field was applied to the isolated isotropic and anisotropic phases. UV-induced polymerization of HEMA perpetuated the respective states of magnetic orientation invested for the CNC dispersions to yield variously oriented CNC/poly(2-hydroxyethyl methacrylate) composites. The structural characterization was carried out by use of X-ray diffractometry and optical and scanning electron microscopy. The result indicated that CNCs were aligned in the composites distinctively according to the static or rotational magnetic application when the anisotropic phases were used, whereas such a specific CNC orientation was not appreciable when the isotropic phases were sampled. This marks out effectiveness of a coherent response of CNCs in the mesomorphic assembly. In dynamic mechanical experiments in tensile or compressive mode, we observed a clear mechanical anisotropy for the polymer composites synthesized from wholly anisotropic suspensions under static or rotational magnetization. The higher modulus (in compression) was detected for a composite reinforced by locking-in the uniaxial CNC alignment attainable through conversion of the initial chiral nematic phase into a nematic phase in the rotational magnetic field. PMID:25390070

Tatsumi, Mio; Kimura, Fumiko; Kimura, Tsunehisa; Teramoto, Yoshikuni; Nishio, Yoshiyuki

2014-12-01

107

Transmitter function of synapse-structure system using conducting polymer  

International Nuclear Information System (INIS)

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

108

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)

109

FTIR AND IONIC CONDUCTIVITY STUDIES ON BLEND POLYMER ELECTROLYTES  

OpenAIRE

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

110

Colloidal infrared reflective and transparent conductive aluminum-doped zinc oxide nanocrystals  

Energy Technology Data Exchange (ETDEWEB)

The present invention provides a method of preparing aluminum-doped zinc oxide (AZO) nanocrystals. In an exemplary embodiment, the method includes (1) injecting a precursor mixture of a zinc precursor, an aluminum precursor, an amine, and a fatty acid in a solution of a vicinal diol in a non-coordinating solvent, thereby resulting in a reaction mixture, (2) precipitating the nanocrystals from the reaction mixture, thereby resulting in a final precipitate, and (3) dissolving the final precipitate in an apolar solvent. The present invention also provides a dispersion. In an exemplary embodiment, the dispersion includes (1) nanocrystals that are well separated from each other, where the nanocrystals are coated with surfactants and (2) an apolar solvent where the nanocrystals are suspended in the apolar solvent. The present invention also provides a film. In an exemplary embodiment, the film includes (1) a substrate and (2) nanocrystals that are evenly distributed on the substrate.

Buonsanti, Raffaella; Milliron, Delia J

2015-02-24

111

Lithium ion conductive polymer electrolyte by side group rotation  

Energy Technology Data Exchange (ETDEWEB)

Ionic conductive materials are of much interest as an electrolyte for solid-state lithium batteries. Poly(alkylene oxide) and lithium salt complex exhibits high ionic conductivity in terms of its high solubility for lithium salts. However, the temperature dependency of its ionic conductivity is quite large and non-linear, the ionic conductivity drops down at low temperature, especially below glass transition temperature of the polymer. Because its ionic conductive mechanism is derived from its segmental motion of polymer main chain. A novel ionic conductive material, poly[2,6-dimethoxy-N-(4-vinylphenyl)benzamide] is synthesized and confirm ionic conductivity even below glass transition temperature. Ionic conductivity of the polymer with lithium ditrifluoromethylsulfonate imide complex shows 10{sup -5}Scm{sup -1} from 0 to 60{sup o}C. Its temperature dependency is linear, namely Arrehnius type dependency. Evaluating from these data, activation energy of ionic conductivity for temperature region from 20 to 60{sup o}C is calculated as 31kJmol{sup -1} and that for temperature region from -20 to 20{sup o}C is 11kJmol{sup -1}. Judging from these results, we conclude that the ionic conductivity of the polymer salt complex derived from 2,6-dimethoxyphenyl group rotation, instead of segmental motion of the polymer. (author)

Sato, Akira; Okumura, Takefumi; Nishimura, Shin [Hitachi Research Laboratory, Hitachi, Ltd., Omika, Hitachi, Ibaraki 319-1292 (Japan); Yamamoto, Hitoshi; Ueyama, Norikazu [Department of Macromolecular Science, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043 (Japan)

2005-08-26

112

Properties of polymer blends filled with mixtures of conductive fillers  

Science.gov (United States)

High-density polyethylene (HDPE), ultrahigh molecular weight polyethylene (UHMWPE) and blends thereof are used to produce ternary and quaternary conductive polymer composites (CPCs) containing carbon black (CB), carbon graphite (G), carbon fiber (CF) and selected mixtures thereof to discern if polymer blends and mixed fillers yield appreciable advantages over CPCs composed of single polymers and/or single fillers. The effects of polymer blend composition and filler type, concentration and composition on electrical conductivity, composite morphology, mechanical properties and thermal behavior have been examined and correlated to establish meaningful structure-property relationships that can facilitate the rational design of efficient CPCs. Enhanced conductivity due to double-percolation is observed in ternary CPCs containing CB or G, whereas the concept of bridged double percolation is proposed to explain substantial conductivity increases in quaternary composites.

Thongruang, Wiriya

2001-11-01

113

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

OpenAIRE

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

114

Hierarchical nanostructured conducting polymer hydrogel with high electrochemical activity  

OpenAIRE

Conducting polymer hydrogels represent a unique class of materials that synergizes the advantageous features of hydrogels and organic conductors and have been used in many applications such as bioelectronics and energy storage devices. They are often synthesized by polymerizing conductive polymer monomer within a nonconducting hydrogel matrix, resulting in deterioration of their electrical properties. Here, we report a scalable and versatile synthesis of multifunctional polyaniline (PAni) hyd...

Pan, Lijia; Yu, Guihua; Zhai, Dongyuan; Lee, Hye Ryoung; Zhao, Wenting; Liu, Nian; Wang, Huiliang; Tee, Benjamin C. -k; Shi, Yi; Cui, Yi; Bao, Zhenan

2012-01-01

115

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

116

Neural Signal Transmission Measurements with a Conductive Polymer Microelectrode Array  

Science.gov (United States)

The neural activity of dissociated cultures of mouse cerebral cortical neurons was measured with a conductive polymer microelectrode array. Each electrode was electrochemically polymerized from (3,4-ethylenedioxythiophene)- poly(styrenesulfonate) and ethylenedioxythiophene on indium tin oxide electrodes. The spike activity of the cortical neurons was measured with the conducting polymer MEA and spike train cross-correlograms were calculated to predict the type of synaptic connection. Both excitatory and inhibitory synaptic connections were identified after 6-8 days in vitro. These results show that it is possible to determine the interaction between excitatory and inhibitory neurons in relation to information processing with this new polymer electrode.

Shimada, Akiyoshi; Kasai, Nahoko; Furukawa, Yuriko; Nyberg, Tobias; Torimitsu, Keiichi

117

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

118

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

Energy Technology Data Exchange (ETDEWEB)

The memory effects of gold (Au) nanocrystal (NC) non-volatile memory structures consisting of polyvinylpyrrolidone (PVP) K-30 polymer tunneling and control layers are investigated. The trilayer structure (PV P/Au-NCs + PV P/PV P) on p-type Si substrate was fabricated by spin coating, and transmission electron microscopy study reveals that the average size of the Au-NCs formed is about 5 nm in diameter. Capacitance-voltage (C-V) measurement on the memory structure shows a counter-clockwise hysteresis loop with a significant flat band voltage shift, revealing a memory effect of the Au-NCs with a charge density of up to 1 x 10{sup 12} cm{sup -2} and a flat band voltage shift of 2.0 V. A unique feature of the double loop in the C-V curves suggests double barriers during electron tunneling. The I-V hysteresis is also characterized, and a switching mechanism of resistive change is discussed.

Lee, P F; Dai, J Y, E-mail: apdaijy@inet.polyu.edu.hk [Department of Applied Physics, Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong)

2010-07-23

119

Flexibility and color monitoring of cellulose nanocrystal iridescent solid films using anionic or neutral polymers.  

Science.gov (United States)

One property of sulfated cellulose nanocrystals (CNCs) is their ability to self-assemble from a concentrated suspension under specific drying conditions into an iridescent film. Such colored films are very brittle, which makes them difficult to handle or integrate within an industrial process. The goal of this study is (i) to produce flexible films using neutral poly(ethylene glycol) (PEG) and (ii) to modulate their coloration using an anionic polyacrylate (PAAS). The first part is dedicated to studying the physicochemical interactions of the two polymers with CNCs using techniques such as zeta potential measurements, dynamic light scattering (DLS), quartz crystal microbalance (QCM), and atomic force microscopy (AFM). Iridescent solid films were then produced and characterized using scanning electron microscopy (SEM) and UV-visible spectroscopy. The mechanical and thermal properties of films incorporating CNC were measured to evaluate improvements in flexibility. The addition of 10 wt % of PEG makes these films much more flexible (with a doubling of the elongation), with the coloration being preserved and the temperature of degradation increasing by almost 35 °C. Up to 160 ?mol/gCNC PAAS can be added to tune the coloration of the CNC films by producing a more narrow, stronger coloration in the visible spectrum (higher absorption) with a well-pronounced fingerprint texture. PMID:25552332

Bardet, Raphael; Belgacem, Naceur; Bras, Julien

2015-02-25

120

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

International Nuclear Information System (INIS)

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

121

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2011-04-15

122

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.

123

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

124

Controlled Li+ conduction pathway to achieve enhanced ionic conductivity in polymer electrolytes  

Science.gov (United States)

Low ionic conductivity is one of the issues for polymer electrolytes to be used in commercial batteries, though they have been viewed as the promising electrolytes in all-solid lithium-ion batteries for several decades. Here, we show an enhanced ionic conductivity in a classic polymer electrolyte by controlling the ionic conductive pathway via a core-shell structure. The enhancement in ionic conductivity is contributed from the formation of a controlled 3D network of the ion conductive amorphous phase. The result suggests that the core-shell structure design can realize the control of the conduction pathway, which is significant for understanding the ionic conductive behaviors as well as for the improvement of the ionic conductivity in polymer electrolytes.

Wang, Yu; Li, Bin; Ji, Jianying; Zhong, Wei-Hong

2014-02-01

125

Composite conduction in ion-implanted polymers  

Science.gov (United States)

The temperature dependence of the dc conductivity for polyamide-imide films, implanted with 50 keV As ions to different fluences, has been studied. Our high-resolution data reveal a two-component conductivity that depends on both one-dimensional variable range hopping (VRH) and three-dimensional VRH. For low fluence levels (5×1015 ions/cm2), the one-dimensional VRH is dominant while at higher fluences (1×1017 ions/cm2), the three-dimensional VRH dominates. These materials become highly disordered and form hard carbon materials along the ion track. The conductivity may be explained by 1D VRH along the ion track at low fluences while at higher fluences, regions of carbon rich material form three-dimensional structures where 3D VRH exists. This rather simple model and its composite conductivity can explain the exact curvature of the temperature dependent conductivity, while single VRH models and percolation models cannot.

Wang, Yongqiang; Bridwell, L. B.; Giedd, R. E.

1993-01-01

126

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

127

Rapid synthesis of flexible conductive polymer nanocomposite films.  

Science.gov (United States)

Polymer nanocomposite films with nanoparticle-specific properties are sought out in novel functional materials and miniaturized devices for electronic and biomedical applications. Sensors, capacitors, actuators, displays, circuit boards, solar cells, electromagnetic shields and medical electrodes rely on flexible, electrically conductive layers or films. Scalable synthesis of such nanocomposite films, however, remains a challenge. Here, flame aerosol deposition of metallic nanosliver onto bare or polymer-coated glass substrates followed by polymer spin-coating on them leads to rapid synthesis of flexible, free-standing, electrically conductive nanocomposite films. Their electrical conductivity is determined during their preparation and depends on substrate composition and nanosilver deposition duration. Accordingly, thin (<500 nm) and flexible nanocomposite films are made having conductivity equivalent to metals (e.g. 5  × 10(4) S cm(-1)), even during repetitive bending. PMID:25736387

Blattmann, C O; Sotiriou, G A; Pratsinis, S E

2015-03-27

128

Mediating conducting polymer growth within hydrogels by controlling nucleation  

Directory of Open Access Journals (Sweden)

Full Text Available This study examines the efficacy of primary and secondary nucleation for electrochemical polymerisation of conductive polymers within poly(vinyl alcohol methacrylate hydrogels. The two methods of nucleation investigated were a primary heterogeneous mechanism via introduction of conductive bulk metallic glass (Mg64Zn30Ca5Na1 particles and a secondary mechanism via introduction of “pre-polymerised” conducting polymer within the hydrogel (PEDOT:PSS. Evidence of nucleation was not seen in the bulk metallic glass loaded gels, however, the PEDOT:PSS loaded gels produced charge storage capacities over 15 mC/cm2 when sufficient polymer was loaded. These studies support the hypothesis that secondary nucleation is an efficient approach to producing stand-alone conducting hydrogels.

A. J. Patton

2015-01-01

129

A computer simulation study of ionic conductivity in polymer electrolytes  

CERN Document Server

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

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

1997-01-01

130

Rapid synthesis of flexible conductive polymer nanocomposite films  

Science.gov (United States)

Polymer nanocomposite films with nanoparticle-specific properties are sought out in novel functional materials and miniaturized devices for electronic and biomedical applications. Sensors, capacitors, actuators, displays, circuit boards, solar cells, electromagnetic shields and medical electrodes rely on flexible, electrically conductive layers or films. Scalable synthesis of such nanocomposite films, however, remains a challenge. Here, flame aerosol deposition of metallic nanosliver onto bare or polymer-coated glass substrates followed by polymer spin-coating on them leads to rapid synthesis of flexible, free-standing, electrically conductive nanocomposite films. Their electrical conductivity is determined during their preparation and depends on substrate composition and nanosilver deposition duration. Accordingly, thin (<500 nm) and flexible nanocomposite films are made having conductivity equivalent to metals (e.g. 5 × 104 S cm?1), even during repetitive bending.

Blattmann, C. O.; Sotiriou, G. A.; Pratsinis, S. E.

2015-03-01

131

Polymer electrolyte membranes with exceptional conductivity anisotropy via holographic polymerization  

Science.gov (United States)

Polymer electrolyte membranes using an ionic liquid as electrolyte with an ionic conductivity anisotropy of ?5000 have been fabricated using a holographic polymerization nanomanufacturing technique. The resultant structure is referred to as holographic polymer electrolyte membranes (hPEMs), which are comprised of alternating nanolayers of a room temperature ionic liquid and crosslinked polymer resin, confirmed under TEM imaging. These hPEMs also show no reduction in room temperature conductivity with respect to the loaded ionic liquid when characterized in the plane of ionic liquid nanolayers. At elevated temperatures with the optimal electrolyte volume loading, calculation shows that the free ion concentration is higher than the pure ionic liquid, suggesting that the photopolymer dual-functionalizes as a loadbearing scaffold and an ion-complexing agent, allowing for more ions to participate in charge transfer. These hPEMs provide a promising solution to decoupling mechanical enhancement and ion transport in polymer electrolyte membranes.

Smith, Derrick M.; Cheng, Shan; Wang, Wenda; Bunning, Timothy J.; Li, Christopher Y.

2014-12-01

132

Water Soluble Conducting Polymer Field Effect Transistor for Sensor Application  

Science.gov (United States)

We studied the water soluble polythiophene based conducting polymer field effect transistor for chemical and biosensors at nanoscale. Sodium poly [2-3(thienyl) ethoxy-4-butylsulphonate)] (SPBS) is a water soluble polymer. Electrical transport property as a function of gate voltage was investigated using a home-built nanomanipulator with four nanoprobes, which is connected to a picoammeter and an impedance analyzer. In conjunction with this, we studied molecular and electronic structures by a scanning tunneling microscope. The interface between electrodes and polymer play an important role in the charge transport properties.

Vaidya, Swanand

2005-03-01

133

Ionic motion in PEDOT and PPy conducting polymer bilayers  

DEFF Research Database (Denmark)

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

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

2006-01-01

134

Light harvesting by dye linked conducting polymers  

Energy Technology Data Exchange (ETDEWEB)

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

Troensegaard Nielsen, K.

2006-06-15

135

Hybridization of conductive few-layer graphene with well-dispersed Pd nanocrystals  

Energy Technology Data Exchange (ETDEWEB)

To improve the activity of Pd nanocrystals (NCs) and maximize the applicability, we used a very simple, low-cost and environmentally benign method to hybridize conductive few-layer graphene with Pd NCs. The TEM results indicated that the monodispersed Pd NCs were well distributed on the graphene surface. The particle size and loading density can be easily tailored by varying reaction times. The XRD and Raman spectrum clearly demonstrated that the pristine exfoliated few-layer graphene are well-crystallized with very low defects, and still preserved the high crystalline structure after the chemical deposition of Pd NCs. Furthermore, this effective process does not require the use of surfactants during the entire reaction, resulting in a clean interface between Pd NCs and graphene substrate, with improved electron transmission. This work presents not only a promising methodology for the mass production of Pd@graphene hybrids, but also opening up the opportunity to develop graphene-Pd based devices for applications in catalysts, sensors and hydrogen storage.

Qian, Wen; Cottingham, Steven [Department of Physics, Portland State University, Portland, OR 97201 (United States); Jiao, Jun, E-mail: jiaoj@pdx.edu [Department of Physics, Portland State University, Portland, OR 97201 (United States)

2013-06-15

136

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

137

Ionically conductive thin polymer films prepared by plasma polymerization  

International Nuclear Information System (INIS)

Ultrathin, uniform, pinhole-free solid polymer electrolyte films of approximately 1 ?m thickness were prepared by the complexation of plasma-polymerized tris(2-methoxyethoxy)vinylsilane (TMVS) with LiClO4. The results of FT-IR, 1H NMR, and 13 C NMR measurements indicate that the structure of the plasma polymer is very similar to poly (TMVS), except for the presence of a small amount of what is probably a cycle group impurity. The glass transition temperature and ionic conductivity of the solid polymer electrolyte depend on the LiClO4 content, and the variation of the ionic conductivity with temperature can be described exactly by using a WLF type of equation. Room temperature conductivities greater than 10- 6 S cm- 1 (102? cm2 resistance per unit area) were observed

138

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

139

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

140

Ionic conductivity enhancement of polymer electrolytes with ceramic nanowire fillers.  

Science.gov (United States)

Solid-state electrolytes provide substantial improvements to safety and electrochemical stability in lithium-ion batteries when compared with conventional liquid electrolytes, which makes them a promising alternative technology for next-generation high-energy batteries. Currently, the low mobility of lithium ions in solid electrolytes limits their practical application. The ongoing research over the past few decades on dispersing of ceramic nanoparticles into polymer matrix has been proved effective to enhance ionic conductivity although it is challenging to form the efficiency networks of ionic conduction with nanoparticles. In this work, we first report that ceramic nanowire fillers can facilitate formation of such ionic conduction networks in polymer-based solid electrolyte to enhance its ionic conductivity by three orders of magnitude. Polyacrylonitrile-LiClO4 incorporated with 15 wt % Li0.33La0.557TiO3 nanowire composite electrolyte exhibits an unprecedented ionic conductivity of 2.4 × 10(-4) S cm(-1) at room temperature, which is attributed to the fast ion transport on the surfaces of ceramic nanowires acting as conductive network in the polymer matrix. In addition, the ceramic-nanowire filled composite polymer electrolyte shows an enlarged electrochemical stability window in comparison to the one without fillers. The discovery in the present work paves the way for the design of solid ion electrolytes with superior performance. PMID:25782069

Liu, Wei; Liu, Nian; Sun, Jie; Hsu, Po-Chun; Li, Yuzhang; Lee, Hyun-Wook; Cui, Yi

2015-04-01

141

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

142

Nanostructure Titania Reinforced Conducting Polymer Composites  

Science.gov (United States)

Composites of polyaniline with synthesized nanostructured titania (TiO2) and polyaniline with commercial TiO2 have been in situ synthesized by oxidative chemical polymerization method. Sulfuric acid was used as dopant during the polymerization process. Sol-gel precipitates of nanostructured titania were synthesized by hydrolyzing the mixture of titanium chloride (TiCl3) and colloidal transparent solution of starch. Composite materials were subjected for comparison to spectroscopic and X-ray diffraction analysis. Strong coupling/interaction of titania with the imine nitrogen in polyaniline confirmed by FTIR spectral analysis. XRD shows the composite of synthesized titania with polyaniline have broaden peak as compared to that of commercial titania with polyaniline indicating particle size in the range of nanometer scale which is supported by 40 nm particle size of the synthesized titania from TEM picture. Increase in conductivity with increasing temperature was observed in both the composite materials.

Kondawar, S. B.; Thakare, S. R.; Khati, V.; Bompilwar, S.

143

EFFECTS OF TRITIUM GAS EXPOSURE ON ELECTRICALLY CONDUCTING POLYMERS  

Energy Technology Data Exchange (ETDEWEB)

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

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

2009-12-16

144

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

145

Microwave assisted click chemistry on a conductive polymer film  

DEFF Research Database (Denmark)

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

Daugaard, Anders Egede; Hansen, Thomas S.

2011-01-01

146

Conductivity study of a gelatin-based polymer electrolyte  

International Nuclear Information System (INIS)

Natural polymers are particularly interesting due to their richness in nature, very low cost and principally biodegradation properties. For these reasons different solid polymeric electrolytes (SPE) have been obtained using cellulose derivatives, starch, chitosan and rubber. This work presents the results of gelatin-based protonic SPEs, which were characterized by impedance spectroscopy, X-ray diffraction, UV-vis-NIR spectroscopy and scanning electron microscopy (SEM). The ionic conductivity results obtained for these SPEs were 4.5 x 10-5 S/cm and 3.6 x 10-4 S/cm at room temperature and 80 deg. C, respectively. Temperature-dependent ionic conductivity measurements were taken to analyze the mechanism of ionic conduction in polymer electrolytes. Good conductivity results combined with transparency and good adhesion to the electrodes have shown that gelatin-based SPEs are very promising materials to be used as solid electrolyte in electrochromic devices

147

Purification of a conducting polymer, polyaniline, for biomedical applications.  

Czech Academy of Sciences Publication Activity Database

Ro?. 195, September (2014), s. 286-293. ISSN 0379-6779 R&D Projects: GA ?R(CZ) GA13-08944S Institutional support: RVO:61389013 Keywords : biocompatibility * conducting polymer * polyaniline Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.222, year: 2013

Stejskal, Jaroslav; Hajná, Milena; Kašpárková, V.; Humpolí?ek, P.; Zhigunov, Alexander; Trchová, Miroslava

2014-01-01

148

Flexible polymer electronic devices using highly conductive polyaniline electrode  

Science.gov (United States)

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

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

2009-08-01

149

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.

150

A computer simulation study of ionic conductivity in polymer electrolytes  

OpenAIRE

In this paper we present a computer simulation study of ionic conductivity in solid polymeric electrolytes. The multiphase nature of the material is taken into account. The polymer is represented by a regular lattice whose sites represent either crystalline or amorphous regions with the charge carrier performing a random walk. Different waiting times are assigned to sites corresponding to the different phases. A random walk (RW) is used to calculate the conductivity through ...

Bhattacharyya, Aninda Jiban; Middya, T. R.; Tarafdar, S.

1997-01-01

151

Effect of some factors on conductivities of polymer ionic conductors  

International Nuclear Information System (INIS)

The ionic conductivities of some PECH-and PECH-PEO-alkaline salt complexes have been determined. The effect of some factors such as polar group concentration, cation size and anion size as well as procedure of thin film preparation on conductivity of polymer ionic conductor has been studied. For lithium salt complex the polar group reduces the conductivity, while for sodium salt complex the polar group enhances the conductivity. This phenomenon was explained by a model involving the existence of two kinds of potential well in the polymers. It has been found that the cation size has strong influence on conductivity. For both small Li+ and large K+, the conductivity is low but for mediun size Na+, the conductivity is high. An ion transport picture in amorphous PECH has been proposed to illustrate this behaviour. In addition, it was shown that the larger the anion size is, the lower the conductivity will be. Finally, the results suggested that the procedure of thin film preparation influenced the film conductivity

152

Reducing thermal transport in electrically conducting polymers: Effects of ordered mixing of polymer chains  

Science.gov (United States)

Reducing the phonon thermal conductivity of electrically conducting polymers can facilitate their use as potential thermoelectric materials. Thus, the influence of the coupling between the longitudinal and transverse phonon modes on overall thermal conductivity is explored for binary mixtures of polyaniline (PANI) and polyacetylene (PA) chains by considering various geometric polymer mixture configurations. The molecular simulations reveal that an increase in the interfacial area available for transverse interactions between dissimilar chains enhances atomic interactions that are orthogonal to the heat transfer direction. As transverse collisions between PA and PANI chains are enhanced, the motion of longitudinal phonons is disrupted, impeding thermal transport. This enhances phonon scattering and reduces longitudinal thermal transport. While there is a nonlinear decrease in the phonon thermal conductivity with increasing interfacial contact area, there is a corresponding linear growth in the nonbonded interaction energies between the different polymers.

Pal, Souvik; Balasubramanian, Ganesh; Puri, Ishwar K.

2013-01-01

153

Ion-conducting polymers Quenched to dynamic disorder  

CERN Document Server

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

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

1999-01-01

154

Optical study on conducting polymer-based field effect devices  

Science.gov (United States)

¡°Optical study on conducting polymer-based field effect devices ¡° Y.M. Kim, F.C. Hsu, N.R. Chiou, J.H. Park, O. Waldmann, V.N. Prigodin, A. J. Epstein, The Ohio State University Time variation of source-drain current with gate modulation of conducting polymer-based field effect devices was studied by in-situ mid-infrared(MIR) reflectance measurements. The transistor-like field effect devices were fabricated using aluminum gate which also works as an optically reflective layer, several different insulating polymers, and poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonic acid)(PEDOT/PSS) active layer. The MIR reflectance measurement of the response to application of a gate voltage shows reflectivity change proportional to the source-drain current variation, shift in interference pattern, and no significant change in phonon features. For the specular reflectance measurement, about 1cm x 1cm area, and 0.1 1 micron thick active layer was prepared, and the insulating layer thickness was also 0.1 1 micron. Because of the small thickness compared to the penetration depth of the PEDOT/PSS, there are the transmission dominant region and the reflectance dominant region, and the reflectivity was increased in the transmission dominant and decreased and in the reflectance dominant region. The results are compared with models for the field effect control of conductance of doped polymers. Supported by ONR Grant No. N00014-01-1-0427.

Kim, Youngmin; Hsu, Fang-Chi; Chiou, Nan-Rong; Park, June Hyoung; Waldmann, Oliver; Prigodin, Vladimir; Epstein, Arthur J.

2003-03-01

155

Hybrid proton-conducting membranes for polymer electrolyte fuel cells  

International Nuclear Information System (INIS)

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

156

Hybrid proton-conducting membranes for polymer electrolyte fuel cells  

Energy Technology Data Exchange (ETDEWEB)

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

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

2005-08-30

157

Investigations of proton conducting polymers and gas diffusion electrodes in the polymer electrolyte fuel cell  

OpenAIRE

Polymer electrolyte fuel cells (PEFC) convert the chemically bound energy in a fuel, e.g. hydrogen, directly into electricity by an electrochemical process. Examples of future applications are energy conversion such as combined heat and power generation (CHP), zero emission vehicles (ZEV) and consumer electronics. One of the key components in the PEFC is the membrane / electrode assembly (MEA). Both the membrane and the electrodes consist of proton conducting polymers (ionomers). In the membr...

Gode, Peter

2005-01-01

158

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

159

Synthesis of polymer nanostructures with conductance switching properties  

Energy Technology Data Exchange (ETDEWEB)

The present invention is directed to crystalline organic polymer nanoparticles comprising a conductive organic polymer; wherein the crystalline organic polymer nanoparticles have a size of from 10 nm to 200 nm and exhibits two current-voltage states: (1) a high resistance current-voltage state, and (2) a low resistance current-voltage state, wherein when a first positive threshold voltage (V.sub.th1) or higher positive voltage, or a second negative threshold voltage (V.sub.th2) or higher negative voltage is applied to the nanoparticle, the nanoparticle exhibits the low-resistance current-voltage state, and when a voltage less positive than the first positive threshold voltage or a voltage less negative than the second negative threshold voltage is applied to the nanoparticle, the nanoparticle exhibits the high-resistance current-voltage state. The present invention is also directed methods of manufacturing the nanoparticles using novel interfacial oxidative polymerization techniques.

Su, Kai; Nuraje, Nurxat; Zhang, Lingzhi; Matsui, Hiroshi; Yang, Nan Loh

2015-03-03

160

Luminescence quenching of conductive Si nanocrystals via “Linkage emission”: Hopping-like propagation of infrared-excited Auger electrons  

Energy Technology Data Exchange (ETDEWEB)

Phosphorus (P) is an n-type dopant for conductive silicon nanocrystals (Si-nc's), the electrical activation of which may be monitored through a non-radiative Auger recombination process that quenches the Si-nc luminescence. We investigated this quenching mechanism through electrical measurements of Si-nc's. Infrared-excited Auger electron emission as the non-radiative process was directly probed and the dynamics of the process are determined from a frequency response analysis. To explain the dynamics, we propose a model in which Auger electrons with a low kinetic energy establish a local inter-nanocrystal conductance and the repetition of this local conductance results in a constant photocurrent (“linkage emission”). This emission becomes significant by electron filling in the Si-nc's owing to the electrical activation of P, which is consistent with observed luminescence quenching behavior. We found that the IR photo-excited emission is distinct from the thermally induced hopping conduction and show that confined, rather than trapped, charges are the source of the Auger electrons. Thus, the process consumes both confined charges and the recombination energy for Auger emission, which explains the luminescence quenching mechanism of Si-nc:P.

Ishii, Masashi, E-mail: ISHII.Masashi@nims.go.jp [National Institute for Materials Science (NIMS), Tsukuba, Ibaraki 305-0047 (Japan); Crowe, Iain F.; Halsall, Matthew P.; Hamilton, Bruce [Photon Science Institute and School of Electrical and Electronic Engineering, University of Manchester, Manchester M13 9PL (United Kingdom); Knights, Andrew P. [Department of Engineering Physics and Centre for Emerging Device Technologies, McMaster University, Hamilton, Ontario L8S 4L7 (Canada); Gwilliam, Russell M. [Advanced Technology Institute, University of Surrey, Guildford GU2 5XH (United Kingdom)

2014-08-14

161

Luminescence quenching of conductive Si nanocrystals via "Linkage emission": Hopping-like propagation of infrared-excited Auger electrons  

Science.gov (United States)

Phosphorus (P) is an n-type dopant for conductive silicon nanocrystals (Si-nc's), the electrical activation of which may be monitored through a non-radiative Auger recombination process that quenches the Si-nc luminescence. We investigated this quenching mechanism through electrical measurements of Si-nc's. Infrared-excited Auger electron emission as the non-radiative process was directly probed and the dynamics of the process are determined from a frequency response analysis. To explain the dynamics, we propose a model in which Auger electrons with a low kinetic energy establish a local inter-nanocrystal conductance and the repetition of this local conductance results in a constant photocurrent ("linkage emission"). This emission becomes significant by electron filling in the Si-nc's owing to the electrical activation of P, which is consistent with observed luminescence quenching behavior. We found that the IR photo-excited emission is distinct from the thermally induced hopping conduction and show that confined, rather than trapped, charges are the source of the Auger electrons. Thus, the process consumes both confined charges and the recombination energy for Auger emission, which explains the luminescence quenching mechanism of Si-nc:P.

Ishii, Masashi; Crowe, Iain F.; Halsall, Matthew P.; Knights, Andrew P.; Gwilliam, Russell M.; Hamilton, Bruce

2014-08-01

162

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

163

Mechanistic study of silver nanoparticle formation on conducting polymer surfaces.  

Science.gov (United States)

Conducting polymer (polyaniline) sheets are shown to be active substrates to promote the growth of nanostructured silver thin films with highly tunable morphologies. Using the spontaneous electroless deposition of silver, we show that a range of nanostructured metallic features can be controllably and reproducibly formed over large surface areas. The structural morphology of the resulting metal-polymer nanocomposite is demonstrated to be sensitive to experimental parameters such as ion concentration, temperature, and polymer processing and can range from densely packed oblate nanosheets to bulk crystalline metals. The deposition mechanisms are explained using a diffusion-limited aggregation (DLA) model to describe the semi-fractal-like growth of the metal nanostructures. We find these composite films to exhibit strong surface-enhanced Raman (SERS) activity, and the nanostructured features are optimized with respect to SERS activity using a self-assembled monolayer of mercapto-benzoic acid as a model Raman reporter. SERS enhancements are estimated to be on the order of 10(7). Through micro-Raman SERS mapping, these materials are shown to exhibit uniform SERS responses over macroscopic areas. These metal-polymer nanocomposites benefit from the underlying polymer's processability to yield SERS-active materials of almost limitless shape and size and show significant promise for future SERS-based sensing and detection schemes. PMID:21434643

Mack, Nathan H; Bailey, James A; Doorn, Stephen K; Chen, Chien-An; Gau, Han-Mou; Xu, Ping; Williams, Darrick J; Akhadov, Elshan A; Wang, Hsing-Lin

2011-04-19

164

Layered ultrathin proton conductive film based on polymer nanosheet assembly.  

Science.gov (United States)

As described in this paper, a layered ultrathin proton conductive film was prepared using a poly(N-dodecylacrylamide-co-2-acrylamido-2-methylpropanesulfonic acid) (p(DDA/AMPS)) polymer nanosheet. The surface pressure-area isotherm revealed that p(DDA/AMPS) formed a stable monolayer at the air-water interface. The polymer monolayer was transferred onto a solid substrate using the Langmuir-Blodgett technique. X-ray diffraction measurements of a 30-layer film of p(DDA/AMPS) showed clear Kiessig fringes and one Bragg peak, which indicate that the multilayer film took a uniform layered structure. The monolayer thickness was determined as 1.85 nm from the Bragg peak. The proton conductivity of p(DDA/AMPS) polymer nanosheet through the layer plane direction was studied with changing temperature and relative humidity. The proton conductivity of the multilayer film was on the order of 1 × 10?? S/cm at 100% RH with 20 °C and increased to 1 × 10?² S/cm at 70 °C. The proton conductivity of the multilayer film showed a more than 10 times higher value than that of the spin-coated film because of the formation of a uniform and consecutive hydrophilic nanochannel through the hydrophilic region in the multilayer film. PMID:21486094

Matsui, Jun; Miyata, Hiromu; Hanaoka, Yu; Miyashita, Tokuji

2011-05-01

165

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

Science.gov (United States)

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

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

2013-09-01

166

Enhanced conductivity of plasticized polymer electrolytes containing chelating groups  

Energy Technology Data Exchange (ETDEWEB)

Poly(AN-co-GMA-IDA) has been prepared by copolymerizing acrylonitrile (AN) and 2-methylacrylic acid 3-(bis-carboxymethylamino-2-hydroxy-propyl ester) (GMA-IDA). The polymers were mixed with the plasticizer ethylene carbonate (EC) and lithium perchlorate (LiClO{sub 4}) to form gel polymer electrolytes (GPE). Fourier-transform infrared spectroscopy (FT-IR) has revealed that the GMA-IDA unit can improve the dissociation of the lithium salt. Furthermore, the GMA-IDA can hinder the crystallization of EC, thereby improving the conductivity of the GPE. This has been established by differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analysis. The interaction between GMA-IDA and EC has been confirmed by FT-IR and {sup 7}Li solid-state NMR. The maximum conductivity measured in this investigation was 9.75 x 10{sup -4} S cm{sup -1}. (author)

Liang, Yu-Hao; Hung, Chi-Yuan; Chen, Chuh-Yung [Department of Chemical Engineering, National Cheng-Kung University, Tainan 701 (China); Wang, Cheng-Chien [Department of Chemical and Material Engineering, Southern Taiwan University, Tainan 710 (China)

2009-03-01

167

Sub-Micrometer Size Structure Fabrication Using a Conductive Polymer  

Directory of Open Access Journals (Sweden)

Full Text Available Stereolithography that uses a femtosecond laser was employed as a method for multiphoton-sensitized polymerization. We studied the stereolithography method, which produces duplicate solid shapes corresponding to the trajectory of the laser focus point and can be used to build a three-dimensional (3D structure using a conductive polymer. To achieve this, we first considered a suitable polymerization condition for line stereolithography. However, this introduced a problem of irregular polymerization. To overcome this, we constructed a support in the polymerized part using a protein material. This method can stabilize polymerization, but it is not suited for building 3D shapes. Therefore, we considered whether heat accumulation causes the irregular polymerization; consequently, the reduction method of the repetition rate of the femtosecond laser was used to reduce the heating process. This method enabled stabilization and building of a 3D shape using photo-polymerization of a conductive polymer.

Junji Sone

2014-12-01

168

Microstructured polymer composites with enhanced thermal and electrical conduction capabilities  

Science.gov (United States)

This paper introduces polymer composites with locally micro-tailored electric and thermal conductive properties. We concentrate on specially designed orthotropic composites that have modified thermal properties in one preferable direction. This preferable direction can vary from region to region in the composite part to fulfill design objectives. Required local micro-tailoring and optimization of structure for given thermal applications is achieved by exposing liquid polymer suspensions to an electric field and then curing the obtained structure. We present testing results for epoxy resin with various fillers including graphite, silica etc. Obtained orthotropic composites are tested for mechanical and thermal and electrical properties. Elastic modulus, thermal expansion, and thermal conduction are measured for various compositions, directions and degree of orthotropy. The potential of obtained materials for electronic, aerospace and automotive applications are briefly discussed.

Moeller, Daniel K.; Shkel, Yuri M.

2004-07-01

169

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

170

Stimulation of neurite outgrowth using an electrically conducting?polymer  

OpenAIRE

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

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

1997-01-01

171

Synthesis of luminescent and rodlike CdS nanocrystals dispersed in polymer templates  

Science.gov (United States)

A simple synthetic route for the preparation of luminescent and rodlike CdS nanocrystals embedded in poly(BA -co-GMA -co-GMA-IDA) (PBGM) copolymer templates, by soap-free emulsion copolymerization, is presented. In this study, GMA-IDA chelating groups within the copolymer were the coordination sites for chelating Cd2+, at which nanosized CdS nanocrystals were grown by the dry method (H2S) and the wet method (Na2S). The particle size and morphology of CdS nanocrystals were observed by transmission electron microscopy (TEM) and atomic force microscopy (AFM). TEM observations demonstrate that the mean diameters of CdS nanoparticles can be prepared between 1 and 2 nm inside the matrix of PBGM membranes by the dry method and between 3 and 6 nm by the wet method. AFM images reveal that CdS nanocrystals on the surfaces of PBGM membranes formed by the dry method have rodlike morphology. The optical absorption spectra indicate a clear blue-shift in the absorption edge for the PBGM-CdS membranes, such that the bandgaps calculated from the absorption spectra are higher than those calculated for the bulk CdS. The particle sizes, estimated from the bandgaps, are in the nanometre range, suggesting that both the particle size and the bandgap can be adjusted via the mole fraction of GMA-IDA in the PBGM membranes. Luminescence spectrophotometry of the samples also indicates a blue-shift in the emission spectra.

Chu, Yuan-Chih; Wang, Cheng-Chien; Chen, Chuh-Yung

2005-01-01

172

Electrical Conductivity Studies on Proton Conducting Polymer Electrolytes Based on Poly (vinyl Acetate)  

Science.gov (United States)

Proton conducting polymer electrolytes based on Poly (vinyl acetate) (PVAc) and perchloric acid (HClO4) has been prepared by solution casting technique with various compositions. FTIR spectra analysis reveals the interaction between proton and ester oxygen of Poly (vinyl acetate) (PVAc). Ac impedance spectroscopy reveals that 75m%PVAc:25m%HClO4 exhibits maximum conductivity, 6.2×10-2 Scm-1 at room temperature (303K). The increase in conductivity with increase in dopant concentration and temperature may be attributed to the enhanced mobility of the polymer chains, number of charge carriers and rotations of side chains. The temperature dependence of conductivity shows non-arrhenius behaviour at higher temperatures. Dielectric loss spectra show two relaxations ? (high temperature) and ? (low temperature) relaxations in low and high frequency range respectively

Arun Kumar, D.; Savitha, T.; Selvasekarapandian, S.; Baskaran, R.

2006-06-01

173

Na+ Ion Conducting Hot-pressed Nano Composite Polymer Electrolytes  

OpenAIRE

Synthesis, characterization and polymeric battery studies of Na+ ion conducting Nano- Composite Polymer Electrolyte (NCPE) membranes: (1-x) [75PEO: 25NaPO3]: x SiO2, where x = 0 - 15 wt. (%), has been reported. NCPE membranes have been casted using a novel hot-press technique in place of the traditional solution cast method. The dispersal of SiO2 in SPE host: (75PEO: 25NaPO3), a conductivity enhancement of an order of magnitude achieved in NCPE film: [93 (75PEO: 25NaPO3): 7 SiO2]. This has be...

Angesh Chandra; Archan Chandra; Kiran Thakurb

2012-01-01

174

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

175

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

176

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.

177

Conductivity of oriented bis-azo polymer films  

DEFF Research Database (Denmark)

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

Apitz, D.; Bertram, R.P.

2006-01-01

178

New transparent conductive metal based on polymer composite  

Energy Technology Data Exchange (ETDEWEB)

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

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

2011-07-01

179

Smart conducting polymer composites having zero temperature coefficient of resistance.  

Science.gov (United States)

Zero temperature coefficient of resistance (TCR) is essential for the precise control of temperature in heating element and sensor applications. Many studies have focused on developing zero-TCR systems with inorganic compounds; however, very few have dealt with developing zero-TCR systems with polymeric materials. Composite systems with a polymer matrix and a conducting filler show either a negative (NTC) or a positive temperature coefficient (PTC) of resistance, depending on several factors, e.g., the polymer nature and the filler shape. In this study, we developed a hybrid conducting zero-TCR composite having self-heating properties for thermal stability and reliable temperature control. The bi-layer composites consisted of a carbon nanotube (CNT)-based layer having an NTC of resistance and a carbon black (CB)-based layer having a PTC of resistance which was in direct contact with electrodes to stabilize the electrical resistance change during electric Joule heating. The composite showed nearly constant resistance values with less than 2% deviation of the normalized resistance until 200 °C. The CB layer worked both as a buffer and as a distributor layer against the current flow from an applied voltage. This behavior, which was confirmed both experimentally and theoretically, has been rarely reported for polymer-based composite systems. PMID:25351278

Chu, Kunmo; Lee, Sung-Chul; Lee, Sangeui; Kim, Dongearn; Moon, Changyoul; Park, Sung-Hoon

2015-01-14

180

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

181

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)

182

Conductivity enhancement in polymer electrolytes on gamma irradiation  

International Nuclear Information System (INIS)

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

183

High-throughput screening of ionic conductivity in polymer membranes  

International Nuclear Information System (INIS)

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

184

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

185

Hierarchical nanostructured conducting polymer hydrogel with high electrochemical activity  

Science.gov (United States)

Conducting polymer hydrogels represent a unique class of materials that synergizes the advantageous features of hydrogels and organic conductors and have been used in many applications such as bioelectronics and energy storage devices. They are often synthesized by polymerizing conductive polymer monomer within a nonconducting hydrogel matrix, resulting in deterioration of their electrical properties. Here, we report a scalable and versatile synthesis of multifunctional polyaniline (PAni) hydrogel with excellent electronic conductivity and electrochemical properties. With high surface area and three-dimensional porous nanostructures, the PAni hydrogels demonstrated potential as high-performance supercapacitor electrodes with high specific capacitance (?480 F·g-1), unprecedented rate capability, and cycling stability (?83% capacitance retention after 10,000 cycles). The PAni hydrogels can also function as the active component of glucose oxidase sensors with fast response time (?0.3 s) and superior sensitivity (?16.7 ?A·mM-1). The scalable synthesis and excellent electrode performance of the PAni hydrogel make it an attractive candidate for bioelectronics and future-generation energy storage electrodes. PMID:22645374

Pan, Lijia; Yu, Guihua; Zhai, Dongyuan; Lee, Hye Ryoung; Zhao, Wenting; Liu, Nian; Wang, Huiliang; Tee, Benjamin C.-K.; Shi, Yi; Cui, Yi; Bao, Zhenan

2012-01-01

186

Mechanisms of proton conductance in polymer electrolyte membranes  

DEFF Research Database (Denmark)

We provide a phenomenological description of proton conductance in polymer electrolyte membranes, based on contemporary views of proton transfer processes in condensed media and a model for heterogeneous polymer electrolyte membrane structure. The description combines the proton transfer events in a single pore with the total pore-network performance and, thereby, relates structural and kinetic characteristics of the membrane. The theory addresses specific experimentally studied issues such as the effect of the density of proton localization sites (equivalent weight) of the membrane material and the water content of the pores. The effect of the average distance between the sulfonate groups, which changes during membrane swelling, is analyzed in particular, and the factors which determine the temperature dependence of the macroscopic membrane conductance are disclosed. Numerical estimates of the specific membrane conductivity obtained from the theory agree very well with typical experimental data, thereby confirming the appropriateness of the theoretical concepts. Moreover, the versatility of the models offers a useful and transparent frame for combining the analysis of both experimental data and the results of molecular dynamics simulations.

Eikerling, M.; Kornyshev, A. A.

2001-01-01

187

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

188

Relaxation model of radiation-induced conductivity in polymers  

International Nuclear Information System (INIS)

The paper suggests a relaxation model of radiation-induced conductivity (RIC) in polymers. According to the model, the transfer of charges generated in the polymer volume by ionizing radiation takes place with the participation of molecular relaxation processes. The mechanism of electron transport consists in the transfer of the charge directly between traps when they draw close to one another due to the rotation of macromolecule segments. The numerical solutions of the corresponding kinetic equations for different distribution functions Q(?) of the times of molecular relaxation and for different functions of the probability P(?, ?') of charge transfer in the 'overlapping' regions of the diffusion spheres of the segments are analyzed. The relaxation model provides an explanation of the non-Arrhenius behavior of the RIC temperature dependence, the power dependence of RIC on the dose rate with a power index in the interval 0.5-1.0, the appearance of maxima in the curves of the RIC temporal dependence and their irreversible character in the region of large dose rates (more than 1 Gy/s). The model can be used for interpreting polymer RIC in conditions of kinetic mobility of macromolecules

189

Smart conducting polymer composites having zero temperature coefficient of resistance  

Science.gov (United States)

Zero temperature coefficient of resistance (TCR) is essential for the precise control of temperature in heating element and sensor applications. Many studies have focused on developing zero-TCR systems with inorganic compounds; however, very few have dealt with developing zero-TCR systems with polymeric materials. Composite systems with a polymer matrix and a conducting filler show either a negative (NTC) or a positive temperature coefficient (PTC) of resistance, depending on several factors, e.g., the polymer nature and the filler shape. In this study, we developed a hybrid conducting zero-TCR composite having self-heating properties for thermal stability and reliable temperature control. The bi-layer composites consisted of a carbon nanotube (CNT)-based layer having an NTC of resistance and a carbon black (CB)-based layer having a PTC of resistance which was in direct contact with electrodes to stabilize the electrical resistance change during electric Joule heating. The composite showed nearly constant resistance values with less than 2% deviation of the normalized resistance until 200 °C. The CB layer worked both as a buffer and as a distributor layer against the current flow from an applied voltage. This behavior, which was confirmed both experimentally and theoretically, has been rarely reported for polymer-based composite systems.Zero temperature coefficient of resistance (TCR) is essential for the precise control of temperature in heating element and sensor applications. Many studies have focused on developing zero-TCR systems with inorganic compounds; however, very few have dealt with developing zero-TCR systems with polymeric materials. Composite systems with a polymer matrix and a conducting filler show either a negative (NTC) or a positive temperature coefficient (PTC) of resistance, depending on several factors, e.g., the polymer nature and the filler shape. In this study, we developed a hybrid conducting zero-TCR composite having self-heating properties for thermal stability and reliable temperature control. The bi-layer composites consisted of a carbon nanotube (CNT)-based layer having an NTC of resistance and a carbon black (CB)-based layer having a PTC of resistance which was in direct contact with electrodes to stabilize the electrical resistance change during electric Joule heating. The composite showed nearly constant resistance values with less than 2% deviation of the normalized resistance until 200 °C. The CB layer worked both as a buffer and as a distributor layer against the current flow from an applied voltage. This behavior, which was confirmed both experimentally and theoretically, has been rarely reported for polymer-based composite systems. Electronic supplementary information (ESI) available: Normalized resistance as a function of increasing temperature for CNTs with different aspect ratios, other configurations of the bi-layered composite with the corresponding circuit diagrams, an SEM image of the CNT/PDMS composite with low resolution and dependence of DC conductivity on the number of three roll passes, numerically calculated normalized resistance of the bi-layer composite with different thickness ratios, streamlines and arrow plots of the current densities of the bi-layer composites with other configurations. See DOI: 10.1039/c4nr04489d

Chu, Kunmo; Lee, Sung-Chul; Lee, Sangeui; Kim, Dongearn; Moon, Changyoul; Park, Sung-Hoon

2014-12-01

190

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

191

Contaminant absorption and conductivity in polymer electrolyte membranes  

Science.gov (United States)

During its lifetime, the polymer electrolyte membrane of a fuel cell may be exposed to numerous impurities originating from sources such as materials used in various components of the fuel cell stack and contaminants in the coolant and reactant gas. The contamination of the membrane by cationic impurities has detrimental effects on membrane properties with regard to conductivity, water management and durability. Thus the measurement of absorption of contaminants into the membrane and the investigation of its relation to these detrimental effects is of interest. Samples of Nafion 117 polymer electrolyte membrane were soaked in deionised water solutions containing part per million (ppm) concentrations of cation impurities, ranging from 0.1 to 100 ppm. Upon removal of the membranes from the soaking solutions, conductivity of the membranes and the effect of different cationic impurity concentrations on the conductivity was measured by impedance spectroscopy methods. Using atomic absorption spectrophotometry, the concentration of the cationic impurity species remaining in the soaking solutions was determined and the extent of ion absorption by the membranes calculated. Energy dispersive X-ray analysis was also employed and confirmed the presence of the contaminant ions in the membrane. Impedance studies exhibited a loss of conductivity, while an increase in ion absorption into the membrane was observed, when membranes were soaked in solutions of higher contaminant concentration. In this study, the capacity for ion absorption into the membranes was determined and the extent of membrane contamination was compared and correlated with the loss in conductivity of the membrane for different levels of contamination.

Kelly, Michael J.; Fafilek, Günter; Besenhard, Jürgen O.; Kronberger, Hermann; Nauer, Gerhard E.

192

Electrical Conductivity in Polymer Blends/ Multiwall Carbon Nanotubes  

International Nuclear Information System (INIS)

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

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

Amplified spontaneous emission in polymer-CdSe/ZnS-nanocrystal DFB structures produced by the holographic method  

Energy Technology Data Exchange (ETDEWEB)

Amplified spontaneous emission (ASE) is demonstrated in volume-distributed feedback (DFB) structures, formed by colloidal CdSe/ZnS nanocrystals and ZrO{sub 2} nanoparticles (NPs) in a polymer matrix. Periodic redistribution of the NPs in an organic matrix was carried out by holographic photopolymerization in a specially developed light-sensitive nanocomposite. The composite consists of two acrylate monomers and two types of inorganic NPs. The NPs provide for the formation of two co-phased gratings-a refractive index grating and an optical gain (losses) grating. The core-shell CdSe/ZnS nanocrystals are used as a gain medium, while ZrO{sub 2} NPs create the refractive index grating and enhance the distributed feedback. The period of the volume structure provides the feedback for lasing at the wavelength {lambda}{sub las} of about 575 nm in the second diffraction order. In contrast to known laser systems based on volume DFB cavities, in which the different components of the formulation provide optical gain and feedback, in our case the inorganic NPs serve as an emitting material and can provide simultaneously for feedback. By pumping of DFB structures by a titanium-sapphire laser ({lambda}{sub pump} = 400 nm, pulse duration of 120 fs) normal to the sample plane, the appearance of a sharp stimulated emission along the grating-vector direction is observed. Output intensity of ASE as a function of the pump energy shows a threshold behavior and full width at half-maximum (FWHM) of the ASE spectral band decreases from 33 to 12 nm.

Smirnova, T N; Yezhov, P V; Kokhtych, L M [Institute of Physics, National Academy of Science, prospect Nauki 46, 03028 Kiev (Ukraine); Sakhno, O V; Stumpe, J [Fraunhofer Institute for Applied Polymer Research, Science Campus Golm, Geiselbergstrasse 69, D-14476 Potsdam (Germany); Goldenberg, L M [Institute for Thin Film Technology and Microsensorics, Kantstrasse 55, D-14513 Teltow (Germany)], E-mail: smirnova@iop.kiev.ua, E-mail: Oksana.Sakhno@iap.fraunhofer.de

2009-06-17

197

Amplified spontaneous emission in polymer-CdSe/ZnS-nanocrystal DFB structures produced by the holographic method  

International Nuclear Information System (INIS)

Amplified spontaneous emission (ASE) is demonstrated in volume-distributed feedback (DFB) structures, formed by colloidal CdSe/ZnS nanocrystals and ZrO2 nanoparticles (NPs) in a polymer matrix. Periodic redistribution of the NPs in an organic matrix was carried out by holographic photopolymerization in a specially developed light-sensitive nanocomposite. The composite consists of two acrylate monomers and two types of inorganic NPs. The NPs provide for the formation of two co-phased gratings-a refractive index grating and an optical gain (losses) grating. The core-shell CdSe/ZnS nanocrystals are used as a gain medium, while ZrO2 NPs create the refractive index grating and enhance the distributed feedback. The period of the volume structure provides the feedback for lasing at the wavelength ?las of about 575 nm in the second diffraction order. In contrast to known laser systems based on volume DFB cavities, in which the different components of the formulation provide optical gain and feedback, in our case the inorganic NPs serve as an emitting material and can provide simultaneously for feedback. By pumping of DFB structures by a titanium-sapphire laser (?pump = 400 nm, pulse duration of 120 fs) normal to the sample plane, the appearance of a sharp stimulated emission along the grating-vector direction is observed. Output intensity of ASE as a function of the pump energy shows a threshold behavior and full width at half-maxhold behavior and full width at half-maximum (FWHM) of the ASE spectral band decreases from 33 to 12 nm.

198

Abnormal temperature dependence of mobility in conjugated polymer / nanocrystal composite: experiment and theory  

OpenAIRE

Instead of normal non-Arrhenius relationship, the carrier mobility $ln({\\mu})$ v.s. $1/T^2$ showed abnormal dependence in an MEH-PPV / InP nanocrystal composite system that a critical temperature $(T_c)$ behavior is prominent in temperature range of 233 K to 333 K. Here, in the model of variable range hopping theory, an analytical model is developed within a Gaussian trap distribution, which is successfully implemented on that phenomenon. The results show that Tc becomes the...

Zhang, Yating; Yao, Jianquan; Kwok, Hoi Sing

2013-01-01

199

Conducting polymers on non-conducting substrates: Chemical coating processes and applications  

International Nuclear Information System (INIS)

The presentation will be as follows: emdash Historical background emdash Oxidizing polymerization mechanism of heterocycles and aromatic compounds: the cases of pyrrole and anilin emdash The processes: solute, gas phase and from conducting polymer solutions emdash The substrates: glass, polymers, inorganic materials, textiles, powders. emdash Properties of coatings: emdash Chemical properties: redox, acid-base emdash Properties resulting from the polymer doping counter-ion emdash Physical properties: : optical, magnetic, conducting, microwave absorption emdash Stability emdash Applications: optics, microelectronics, sensors, electrochrome glasses, electromagnetic and antistatic shielding, military applications, packaging for electronic components, biocompat- ibility, plasturgy. emdash Commercial applications throughout the world. How to obtain these materials emdash Conclusions The examples will be taken from the results of our laboratory, those of CEA-Direction des Technologies Avancacute ees emdash Centre d close-quote Etudes et de Recherche sur les Matacute eriaux emdash Centre d close-quote Etudes Nuclacute eaires de Grenoble (Mssrs R. Jolly and J. C. Thiacute eblemont), from the Milliken Research Corp. (Dr. H. H. Kuhn), from the Zipperlin Kessler company (Dr. B. Wessling), from the Americhem company and from I.B.M. (Dr. M. Angelopoulos). copyright 1996 American Institute of Physics

200

Conducting polymers on non-conducting substrates: Chemical coating processes and applications  

Science.gov (United States)

The presentation will be as follows: —Historical background —Oxidizing polymerization mechanism of heterocycles and aromatic compounds: the cases of pyrrole and anilin —The processes: solute, gas phase and from conducting polymer solutions —The substrates: glass, polymers, inorganic materials, textiles, powders. —Properties of coatings: —Chemical properties: redox, acid-base —Properties resulting from the polymer doping counter-ion —Physical properties: : optical, magnetic, conducting, microwave absorption —Stability —Applications: optics, microelectronics, sensors, electrochrome glasses, electromagnetic and antistatic shielding, military applications, packaging for electronic components, biocompat- ibility, plasturgy. —Commercial applications throughout the world. How to obtain these materials —Conclusions The examples will be taken from the results of our laboratory, those of CEA-Direction des Technologies Avancées—Centre d'Etudes et de Recherche sur les Matériaux—Centre d'Etudes Nucléaires de Grenoble (Mssrs R. Jolly and J. C. Thiéblemont), from the Milliken Research Corp. (Dr. H. H. Kuhn), from the Zipperlin Kessler company (Dr. B. Wessling), from the Americhem company and from I.B.M. (Dr. M. Angelopoulos).

Geniès, Eugène M.

1996-01-01

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

Thermal Conductivity of Carbon Nanotubes and their Polymer Nanocomposites: A Review  

OpenAIRE

Thermally conductive polymer composites offer new possibilities for replacing metal parts in several applications, including power electronics, electric motors and generators, heat exchangers, etc., thanks to the polymer advantages such as light weight, corrosion resistance and ease of processing. Current interest to improve the thermal conductivity of polymers is focused on the selective addition of nanofillers with high thermal conductivity. Unusually high thermal conductivity makes carbon ...

Han, Zhidong; Fina, Alberto

2011-01-01

203

Conductivity enhancement of conjugated polymer after HCl-methanol treatment  

International Nuclear Information System (INIS)

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

204

Analysis of surface modified polymers: XPS and conductivity measurements  

International Nuclear Information System (INIS)

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

205

Photochemical formation of electrically conductive silver nanowires on polymer scaffolds.  

Science.gov (United States)

A photochemical method has been exploited for the synthesis of electrically conductive silver (Ag) nanowires in a polymer solution in the presence of negatively charged Au seed particles. The synthesis was completed within 8 min of UV-photoirradiation in ambient conditions. The nanowires were fabricated on a PVA template having an average diameter of 135+/-20 nm and a length of 10-20 microm. The current-voltage (I-V) characterization showed that the PVA-Ag nanowires were continuous, having Ohmic behavior with low contact resistance. Results indicate that the PVA acted as a reducing agent, stabilizing agent, and a template for the nucleation and growth of Ag nanowires. The Ag deposition was highly selective and on the PVA only. Our research indicated that the PVA-Ag nanowires might be useful as interconnects in nanoscale integrated circuitry, functional nanodevices, and in optoelectronics. PMID:20138630

Kundu, Subrata; Huitink, David; Wang, Ke; Liang, Hong

2010-04-15

206

Conductive Polymer Porous Film with Tunable Wettability and Adhesion  

Directory of Open Access Journals (Sweden)

Full Text Available A conductive polymer porous film with tunable wettability and adhesion was fabricated by the chloroform solution of poly(3-hexylthiophene (P3HT and [6,6]-phenyl-C61-butyricacid-methyl-ester (PCBM via the freeze drying method. The porous film could be obtained from the solution of 0.8 wt%, whose pore diameters ranged from 50 nm to 500 nm. The hydrophobic porous surface with a water contact angle (CA of 144.7° could be transferred into a hydrophilic surface with CA of 25° by applying a voltage. The water adhesive force on the porous film increased with the increase of the external voltage. The electro-controllable wettability and adhesion of the porous film have potential application in manipulating liquid collection and transportation.

Yuqi Teng

2015-04-01

207

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)

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

Complex impedance and conductivity of agar-based ion-conducting polymer electrolytes  

Science.gov (United States)

Agar-based electrolyte standing films with different salts and weak acids as ion and proton conductors were prepared and characterized by X-ray diffraction, UV-visible spectrophotometry, photoluminescence emission spectroscopy and electrochemical impedance spectroscopy. The salts used are lithium perchlorate (LiClO4) and potassium perchlorate (KClO4), while the weak acids used are acetic acid (CH3COOH) and lactic acid (C3H6O3). The values of the ion conductivity obtained for the agar-based polymer films are 6.54 × 10-8, 9.12 × 10-8, 3.53 × 10-8, 2.24 × 10-8 S/cm for the agar/acetic acid, agar/lactic acid, agar/LiClO4 and agar/KClO4 polymer films, respectively. As a function of temperature, the ion conductivity exhibits an Arrhenius behavior and the estimated activation energy is ?0.1 eV for all the samples. The samples depicted high values of dielectric permittivity toward low frequencies which is due mostly to electrode polarization effect. The samples showed very high transparency (85-98 %) in the visible region, and this high transparency is one of the major requirements for application in electrochromic devices (ECD). The values of conductivity and activation energy obtained indicate that the electrolytes are good materials for application in ECD.

Nwanya, A. C.; Amaechi, C. I.; Udounwa, A. E.; Osuji, R. U.; Maaza, M.; Ezema, F. I.

2015-04-01

210

Complex impedance and conductivity of agar-based ion-conducting polymer electrolytes  

Science.gov (United States)

Agar-based electrolyte standing films with different salts and weak acids as ion and proton conductors were prepared and characterized by X-ray diffraction, UV-visible spectrophotometry, photoluminescence emission spectroscopy and electrochemical impedance spectroscopy. The salts used are lithium perchlorate (LiClO4) and potassium perchlorate (KClO4), while the weak acids used are acetic acid (CH3COOH) and lactic acid (C3H6O3). The values of the ion conductivity obtained for the agar-based polymer films are 6.54 × 10-8, 9.12 × 10-8, 3.53 × 10-8, 2.24 × 10-8 S/cm for the agar/acetic acid, agar/lactic acid, agar/LiClO4 and agar/KClO4 polymer films, respectively. As a function of temperature, the ion conductivity exhibits an Arrhenius behavior and the estimated activation energy is ?0.1 eV for all the samples. The samples depicted high values of dielectric permittivity toward low frequencies which is due mostly to electrode polarization effect. The samples showed very high transparency (85-98 %) in the visible region, and this high transparency is one of the major requirements for application in electrochromic devices (ECD). The values of conductivity and activation energy obtained indicate that the electrolytes are good materials for application in ECD.

Nwanya, A. C.; Amaechi, C. I.; Udounwa, A. E.; Osuji, R. U.; Maaza, M.; Ezema, F. I.

2015-01-01

211

Structure-conductivity studies in polymer electrolytes containing multivalent cations  

International Nuclear Information System (INIS)

Understanding the structure - conductivity relationship is of paramount importance for the development of polymer electrolytes. The present studies present the techniques found useful in the elucidation of structure - conductivity relationship in PEOn:ZnBr2 (n = 8, 1000, 2000, 3000, 4000 and 5000) and PEOn:FeBrx (n= 8, 20 and 50; x = 2 and 3). Local structural studies have been undertaken using X-ray absorption fine structures (XAFS) which includes extended X-ray absorption fine structure (EXAFS) and X-ray absorption near edge structure (XANES). EXAFS provides interatomic distance and coordination numbers of the nearest neighbours and results from the EXAFS studies showed that high conductivity is associated with stretched M - O interatomic distance. In the studies on ultra dilute Zn samples it was found that the cation is highly solvated by the heteroatom forming a tightly bound environment which inhibits local segmental motion thus impeding ion migration. XANES studies on the PEO and modified PEO complexes of NiBr2 revealed the sensitivity of XANES to the structural differences. XANES on Zn and Fe samples also revealed the sensitivity to changes in interatomic distances reflected in shifts of the white line. The complementary nature of EXAFS and XANES was reflected in the studies conducted. Morphological studies were undertaken employing differential scanning calorimetry (DSC), variable temperature polarising mi (DSC), variable temperature polarising microscopy (VTPM) and atomic force microscopy (AFM). DSC evidences helped to explain the texture of the iron samples during the drying process, and showed transitions between low melting, PEO and high melting spherulites, and VTPM is able to visualise the spherulites present in the samples. AFM has successfully imaged the as cast PEO8:FeBr2 sample and the surface effect causing extra resistance in the impedance spectra could be seen. Conductivity studies were carried out using a.c. impedance spectra. Fe(ll) samples exhibit the typical semicircle-spike plot but the Fe(lll) samples displayed an extra semicircle before the spike reflecting a surface effect. This is also manifested in the Arrhenius plots of the same samples where a dip was shown at 100 deg C. From the conductivity studies on the iron systems it was found that for the dry samples the optimum conductivity was observed in PEO8:FeBrx irrespective of the valence state of the cation. For the air-cast samples the optimum conductivity composition depends on the valence state and were shown to be at more dilute compositions. (author)

212

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

OpenAIRE

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

213

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

OpenAIRE

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

214

Near IR-sensitive, non-toxic, polymer/nanocrystal solar cells employing Bi{sub 2}S{sub 3} as the electron acceptor  

Energy Technology Data Exchange (ETDEWEB)

Bi{sub 2}S{sub 3} nanocrystals are employed in a polymer/nanocrystal solar cell as a non-toxic inorganic electron acceptor with a high absorption coefficient and a bandgap of 1.3 eV optimal for single-junction solar harnessing. The reported solar cell yields a power conversion efficiency of 0.46% in a bilayer structure and shows an internal quantum efficiency in excess of 70% as a result of efficient exciton dissociation at the interface of Bi{sub 2}S{sub 3} and P3HT. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Martinez, Luis; Bernechea, Maria; De Arquer, F.P.G.; Konstantatos, Gerasimos [ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, Castelldefels, Barcelona (Spain)

2011-11-15

215

Designer coordination polymers: dimensional crossover architectures and proton conduction.  

Science.gov (United States)

Coordination polymers (CPs) have large degrees of freedom in framework compositions and in the structures and environment of the inner pores. This review focuses on the recent significant progress achieved by controlling these degrees of freedom. Two breakthroughs are reviewed for constructing sophisticated structures of CP frameworks, especially in dimensional crossover regions. The first is the synthesis of quasi one-dimensional halogen-bridged coordinative tubes by applying state-of-the-art techniques of coordination chemistry. The electronic state of the coordinative tube was studied by structural, spectroscopic and theoretical methods and found to be distinct from conventional one-dimensional systems. The second breakthrough is the achievement of a quasi-two-dimensional architecture by combining Langmuir-Blodgett and layer-by-layer methods. Two-dimensional LB CP films were prepared on liquid; the films were stacked layer by layer, and a crystalline quasi-two-dimensional structure was constructed. This review also covers the design of the environment of the inner pore, where hydrogen bond networks with various acidic sites were modified. By appropriate design of the hydrogen bond network, proton-conductive CPs are invented, which are summarized in this review. Types of proton donor sites are discussed and classified, and superprotonic conductive CPs were achieved in these investigations. These results will provide new strategies for constructing functional materials for smart devices. PMID:23817780

Yamada, Teppei; Otsubo, Kazuya; Makiura, Rie; Kitagawa, Hiroshi

2013-08-21

216

A New Conducting Polymer Electrode for Organic Electroluminescence Devices  

International Nuclear Information System (INIS)

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

217

Soft capacitor fibers using conductive polymers for electronic textiles  

International Nuclear Information System (INIS)

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

218

Stimulation of neurite outgrowth using an electrically conducting?polymer  

Science.gov (United States)

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

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

1997-01-01

219

Understanding correlation effects for ion conduction in polymer electrolytes.  

Science.gov (United States)

Polymer electrolytes typically exhibit diminished ionic conductivity due to the presence of correlation effects between the cations and anions. Microscopically, transient ionic aggregates, e.g., ion-pairs, ion-triplets, or higher order ionic clusters, engender ionic correlations. Employing all-atom simulation of a model polymer electrolyte comprising of poly(ethylene oxide) and lithium iodide, the ionic correlations are explored through construction of elementary functions between pairs of the ionic species that qualitatively explains the spatio-temporal nature of these correlations. Furthermore, commencing from the exact Einstein-like equation describing the collective diffusivity of the ions in terms of the average diffusivity of the ions (i.e., the self-terms) and the correlations from distinct pairs of ions, several phenomenological parameters are introduced to keep track of the simplification procedure that finally boils down to the recently proposed phenomenological model by Stolwijk and Obeidi (SO) [Stolwijk, N. A.; Obeidi, S. Phys. Rev. Lett. 2004, 93, 125901]. The approximation parameters, which can be retrieved from simulations, point to the necessity of additional information in order to fully describe the correlation effects apart from the mere fraction of ion-pairs that apparently accounts for the correlations originating from only the nearest neighbor structural correlations. These parameters are close to, but are not exactly unity, as assumed in the SO model. Finally, as an application of the extended SO model, one is able to estimate the dynamics of the free and non-free ions as well as their fractions from the knowledge of the single particle diffusivities and the collective diffusivity of the ions. PMID:18636769

Maitra, Arijit; Heuer, Andreas

2008-08-14

220

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

International Nuclear Information System (INIS)

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

221

Molecular self-assembly of conducting polymer by Conducting Probe Technique in Atomic Force Microscope  

International Nuclear Information System (INIS)

A polypyrrole derivative monolayer was investigated for the application as a wire. First, a pyrrole derivative monolayer was prepared by chemically adsorbing (self-assembling) monolayer (CAM) of 6-pyrrolylhexyl-12,12,12-trichloro-12- siladodecanoate (PEN) on a glass substrate. Then, the monolayer was polymerized in the presence of pure water by electrooxidation. The surface characterization of the molecular interaction was investigated by measuring the properties of CAMs attached to the glass substrate in the lateral direction. We formed PEN having polypyrrolyl groups, using Pt-patterned electrodes on glass surfaces and measured the conductance under a small bias voltage, using a conductive cantilever of atomic force microscopy (AFM). The polypyrrole derivative monolayer thus synthesized was covalently bonded to the glass substrate and showed conductivity as high as 3.05..103 S/cm after electro-oxidized. The method of preparing a conductive polymer monolayer by the combining chemical adsorption and electro-oxidation leads to a lot molecular wire to perpendicular to the Pt electrodes, and it is one of the key technologies for molecular devices

222

Inorganic and biological electron transfer across an electronically conductive composite polymer membrane. Interim report  

Energy Technology Data Exchange (ETDEWEB)

We describe in this paper an experiment involving an electronically conductive polymer that, to our knowledge, has not been described previously. A free-standing conductive polymer (polypyrrole)-based membrane separates a solution of an electron donor from a solution of an electron acceptor. Because the conductive polymer is both electronically and anionically conductive, the membrane can transport electrons from the donor solution to the acceptor solution, and anions in the opposite direction, such that a sustainable electron-transfer reaction is driven across the conductive polymer membrane. We demonstrate such transmembrane electron/ion-transfer processes using both an inorganic and a-biochemical electron donor/acceptor system. The biochemical case is of particular interest because we show that the reduced form of the enzyme glucose oxidase can give its electrons directly to the polypyrrolemembrane surface. Direct electron transfer is usually not possible at inorganic metals.... Biological electron transfer, Conducting polymers.

Lawson, D.R.; Liang, W.; Martin, C.R.

1993-02-22

223

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

Science.gov (United States)

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

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

2010-11-01

224

Using artificial intelligence methods to design new conducting polymers  

Directory of Open Access Journals (Sweden)

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

Ronaldo Giro

2003-12-01

225

A conducting polymer/ferritin anode for biofuel cell applications  

Energy Technology Data Exchange (ETDEWEB)

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

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

2009-06-30

226

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.

227

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

228

A novel conductive polymer-sulfur composite cathode material for rechargeable lithium batteries  

Energy Technology Data Exchange (ETDEWEB)

Conductive polymer-sulfur composites have been reported as potential cathode materials for rechargeable batteries due to their structure, i.e., sulfur embedded in a conductive polymer host at molecular level. The low-cost, environmentally friendly sulfur composite has outstanding electrochemical properties and is, hence, a highly interesting material for the next generation of lithium batteries. (Abstract Copyright[2002], Wiley Periodicals, Inc.)

Wang Jiulin; Yang Jun; Xie Jingying; Xu Naixin [Energy Science and Technology Laboratory, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200 050 (China)

2002-07-04

229

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

230

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

OpenAIRE

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

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

2012-01-01

231

Methods of enhancing conductivity of a polymer-ceramic composite electrolyte  

Science.gov (United States)

Methods for enhancing conductivity of polymer-ceramic composite electrolytes are provided which include forming a polymer-ceramic composite electrolyte film by a melt casting technique and uniaxially stretching the film from about 5 to 15% in length. The polymer-ceramic composite electrolyte is also preferably annealed after stretching such that it has a room temperature conductivity of from 10.sup.-4 S cm.sup.-1 to 10.sup.-3 S cm.sup.-1. The polymer-ceramic composite electrolyte formed by the methods of the present invention may be used in lithium rechargeable batteries.

Kumar, Binod

2003-12-02

232

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.

233

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

234

Stabilization of Conducting Polymers with CMC: Rheological Approach  

Science.gov (United States)

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

Gangopadhyay, Rupali

2011-07-01

235

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

Science.gov (United States)

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

Bahtiar, Ayi

2013-09-01

236

Preparation of metallic cation conducting polymers based on sterically hindered phenols containing polymeric systems  

Science.gov (United States)

The present invention relates to ion-conducting solvent-free polymeric systems characterized as being cationic single ion conductors. The solvent-free polymer electrolytes comprise a flexible polymer backbone to which is attached a metal salt, such as a lithium, sodium or potassium salt, of a sterically hindered phenol. The solid polymer electrolyte may be prepared either by (1) attaching the hindered phenol directly to a flexible polymeric backbone, followed by neutralization of the phenolic OH's or (2) reacting the hindered phenol with a polymer precursor which is then polymerized to form a flexible polymer having phenolic OH's which are subsequently neutralized. Preferably the hindered phenol-modified polymeric backbone contains a polyether segment. The ionic conductivity of these solvent-free polymer electrolytes has been measured to be in the range of 10.sup.-4 to 10.sup.-7 S cm.sup.-1 at room temperature.

Skotheim, Terje A. (Shoreham, NY); Okamoto, Yoshiyuki (Fort Lee, NJ); Lee, Hung S. (Woodside, NY)

1989-01-01

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

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

OpenAIRE

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

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

2000-01-01

239

Effects of electric field and charge distribution on nanoelectronic processes involving conducting polymers  

OpenAIRE

The injection of charge carriers in conducting polymer layers gives rise to local electric fields which should have serious implications on the charge transport through the polymer layer. The charge distribution and the related electric field inside the ensemble of polymer molecules, with different molecular arrangements at nanoscale, determine whether or not intra-molecular charge transport takes place and the preferential direction for charge hopping between neighbouring molecules. Conseque...

Ramos, Marta M. D.; Correia, Helena M. G.

2006-01-01

240

Spin blockade in the conduction of colloidal CdSe nanocrystal films.  

Science.gov (United States)

The conduction of thin films of n-type CdSe colloidal quantum dots is studied at low temperature and under magnetic field. At medium and high magnetic fields (10 T), the films exhibit positive magnetoresistance consistent with the variable range hopping model. At low magnetic field(magnetoresistance of order 10%-15%. The magnetoresistance shows a strong bias dependence, small and positive at low bias, increasing but still positive at higher bias, and turning negative at the highest bias. A similar behavior has been reported recently for thin film organics. Weak localization effects are ruled out. The explanation for the observations is based on spin blockade relaxed by the hyperfine interaction. The weak magnetoresistance at low bias is attributed to the diffusing paths taken by the hopping electrons. At higher bias, the more directed motion of electrons leads to increasingly positive magnetoresistance due to the more effective spin blockade. At the highest bias, the magnetoresistance becomes negative, which is attributed to the increased exchange interaction associated with the shorter tunneling distance. PMID:17627359

Guyot-Sionnest, Philippe; Yu, Dong; Jiang, Pei-Hsun; Kang, Woowon

2007-07-01

241

High thermal conductivity in amorphous polymer blends by engineered interchain interactions.  

Science.gov (United States)

Thermal conductivity is an important property for polymers, as it often affects product reliability (for example, electronics packaging), functionality (for example, thermal interface materials) and/or manufacturing cost. However, polymer thermal conductivities primarily fall within a relatively narrow range (0.1-0.5 W m(-1) K(-1)) and are largely unexplored. Here, we show that a blend of two polymers with high miscibility and appropriately chosen linker structure can yield a dense and homogeneously distributed thermal network. A sharp increase in cross-plane thermal conductivity is observed under these conditions, reaching over 1.5 W m(-1) K(-1) in typical spin-cast polymer blend films of nanoscale thickness, which is approximately an order of magnitude larger than that of other amorphous polymers. PMID:25419813

Kim, Gun-Ho; Lee, Dongwook; Shanker, Apoorv; Shao, Lei; Kwon, Min Sang; Gidley, David; Kim, Jinsang; Pipe, Kevin P

2015-03-01

242

High thermal conductivity in amorphous polymer blends by engineered interchain interactions  

Science.gov (United States)

Thermal conductivity is an important property for polymers, as it often affects product reliability (for example, electronics packaging), functionality (for example, thermal interface materials) and/or manufacturing cost. However, polymer thermal conductivities primarily fall within a relatively narrow range (0.1–0.5 W m?1 K?1) and are largely unexplored. Here, we show that a blend of two polymers with high miscibility and appropriately chosen linker structure can yield a dense and homogeneously distributed thermal network. A sharp increase in cross-plane thermal conductivity is observed under these conditions, reaching over 1.5 W m?1 K?1 in typical spin-cast polymer blend films of nanoscale thickness, which is approximately an order of magnitude larger than that of other amorphous polymers.

Kim, Gun-Ho; Lee, Dongwook; Shanker, Apoorv; Shao, Lei; Kwon, Min Sang; Gidley, David; Kim, Jinsang; Pipe, Kevin P.

2015-03-01

243

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

Directory of Open Access Journals (Sweden)

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

Mahardika P. Aji

2012-01-01

244

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

Science.gov (United States)

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

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

2013-06-01

245

An Integrated Laboratory Approach toward the Preparation of Conductive Poly(phenylene vinylene) Polymers  

Science.gov (United States)

Poly(phenylene vinylene) (PPV) represents an important class of conjugated, conducting polymers that have been readily exploited in the preparation of organic electronic materials. In this experiment, students prepare a PPV polymer via a facile multistep synthetic sequence with robust spectroscopic evaluation of synthetic intermediates and the…

Knoerzer, Timm A.; Balaich, Gary J.; Miller, Hannah A.; Iacono, Scott T.

2014-01-01

246

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

Science.gov (United States)

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

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

2010-01-01

247

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)

248

Nanowire-filled polymer composites with ultrahigh thermal conductivity  

Science.gov (United States)

Realizing high thermal conductivity nanocomposites is a challenge because of difficulties in incorporating high fractions of uniformly dispersed nanofillers and countering low filler-matrix interfacial conductance. Here, we obviate these issues by using welded networks that enhance thermal conductivity while fostering low modulus and electrical conductivity. Such nanowire nanocomposites are attractive for many applications in electronics, packaging, and energy devices.

Balachander, Nikhil; Seshadri, Indira; Mehta, Rutvik J.; Schadler, Linda S.; Borca-Tasciuc, Theo; Keblinski, Pawel; Ramanath, Ganpati

2013-03-01

249

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

International Nuclear Information System (INIS)

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

250

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...

251

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

Science.gov (United States)

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

252

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

International Nuclear Information System (INIS)

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

253

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

254

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

255

A unified model for temperature dependent electrical conduction in polymer electrolytes  

OpenAIRE

The observed temperature dependence of electrical conduction in polymer electrolytes is usually fitted with two separated equations: an Arrhenius equation at low temperatures and Vogel-Tamman-Fulcher (VTF) at high temperatures. We report here a derivation of a single equation to explain the variation of electrical conduction in polymer electrolytes at all temperature ranges. Our single equation is in agreement with the experimental data

Mikrajuddin; Lenggoro, I. Wuled; Okuyama, Kikuo

2001-01-01

256

Highly electrically conductive nanocomposites based on polymer-infused graphene sponges.  

Science.gov (United States)

Conductive polymer composites require a three-dimensional 3D network to impart electrical conductivity. A general method that is applicable to most polymers for achieving a desirable graphene 3D network is still a challenge. We have developed a facile technique to fabricate highly electrical conductive composite using vacuum-assisted infusion of epoxy into graphene sponge GS scaffold. Macroscopic GSs were synthesized from graphene oxide solution by a hydrothermal method combined with freeze drying. The GS/epoxy composites prepared display consistent isotropic electrical conductivity around 1 S/m, and it is found to be close to that of the pristine GS. Compared with neat epoxy, GS/epoxy has a 12-orders-of-magnitude increase in electrical conductivity, attributed to the compactly interconnected graphene network constructed in the polymer matrix. This method can be extended to other materials to fabricate highly conductive composites for practical applications such as electronic devices, sensors, actuators, and electromagnetic shielding. PMID:24722145

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

2014-01-01

257

Highly Electrically Conductive Nanocomposites Based on PolymerInfused Graphene Sponges  

Science.gov (United States)

Conductive polymer composites require a threedimensional 3D network to impart electrical conductivity. A general method that is applicable to most polymers for achieving a desirable graphene 3D network is still a challenge. We have developed a facile technique to fabricate highly electrical conductive composite using vacuumassisted infusion of epoxy into graphene sponge GS scaffold. Macroscopic GSs were synthesized from graphene oxide solution by a hydrothermal method combined with freeze drying. The GSepoxy composites prepared display consistent isotropic electrical conductivity around 1Sm, and it is found to be close to that of the pristine GS. Compared with neat epoxy, GSepoxy has a 12ordersofmagnitude increase in electrical conductivity, attributed to the compactly interconnected graphene network constructed in the polymer matrix. This method can be extended to other materials to fabricate highly conductive composites for practical applications such as electronic devices, sensors, actuators, and electromagnetic shielding. PMID:24722145

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

2014-01-01

258

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

259

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

Energy Technology Data Exchange (ETDEWEB)

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{sup -4} to 10{sup -3} S cm{sup -1} at room temperature. Gelation was found to cause little change in the {sup 7}Li 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. (author)

Ogihara, Wataru; Yoshizawa, Masahiro; Ohno Hiroyuki [Tokyo University of Agriculture and Technology (Japan). Dept. of Biotechnology; Sun, Jiazeng; Forsyth, M. [Monash University, Clayton (Australia). School of Materials Engineering; MacFarlane, D.R. [Monash University, Clayton (Australia). School of Chemistry

2004-04-30

260

High rate all-solid electrochemical capacitors using proton conducting polymer electrolytes  

Science.gov (United States)

All-solid electrochemical capacitors (EC) utilizing a proton conducting polymer electrolyte and graphite electrodes have demonstrated exceptionally high rate capability. The solid polymer electrolyte-based ECs charge and discharge at sweep rate over 20 V s-1 and exhibit a time constant of 10 ms. This high rate performance is enabled by a proton conducting ternary solid thin film electrolyte composed of silicotungstic acid, orthophosphoric acid, and polyvinyl alcohol. This work shows that solid polymer electrolytes can support high power and high rate energy storage applications.

Gao, Han; Lian, Keryn

2011-10-01

261

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

OpenAIRE

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 th...

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

1997-01-01

262

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

263

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

264

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

265

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.

266

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

267

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

268

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

269

Improving conducting polymer electrochromic speeds and depositing aligned polymeric nanofibers by electrospinning process  

Science.gov (United States)

The effects of film thickness and porosity on electrochromic switching time of conducting polymers was pursued to determine the morphology influence on ions transport during oxidation step of the redox process, affording sub-second or seconds switching times. Electrospinning technique provided non-woven nanofiber mats, while spin coating and electropolymerization of monomer (N3T) provided films. Porosity decreased as depositing method changed from electrospinning to spin coating. In electrochemical oxidation, the electrons leave the polymer at the metal electrode-polymer film interface, and counter ions arrive at the polaron-bipolaron sites left in the polymer, through polymer-electrolyte interface. Counter ion diffusion in conducting polymers are film thickness limited at increasing thickness and inability of ions to reach holes sites on the oxidizing polymer accounts for long switching speeds, introducing extensive and micro pores and high surface areas should lead to decreasing electrochromic switching speed to single digit time in seconds (for display and vision applications), while increasing the maximum optical switching contrast due to increased fiber mat thicknesses. Photolithographic patterning of nanofiber mats of the conducting polymer precursor having photo cross-linking unit was also explored. The photo-crosslinkable polymer was prepared by including norborene methacrylate (NMA) units to the polymer backbone during precursor polymerization, yielding a terpolymer poly(N3T-NA-NMA). The influence of photo crosslinking on electrochemical switching in conducting polymer nanofibers, and effect of developing parameters (solvent and time) on pattern transfer to the nanofiber mat was investigated and showed no influence on the electrochemical redox of the polymer. Solvents suitable for dissolving the polymer were investigated as developers with results showing non-differentiable pattern transfer for all suitable solvents, and no net preference to solvent choice. Lastly, the alignment of electrospun nanofibers during electrospinning was investigated to prepare composites of aligned nanofiber mats on macro-mesh fabric, and control alignment by non-conventional methods. Nanofibers produced during electrospinning are usually collected as non-woven randomly oriented fibers, but by manipulating the electric field at the collector, aligned nanofibers were obtained. Further modifications using a mesh fabric as collector, or using non-conventional conductive surfaces, deposition of continuous and aligned nanofibers of poly lactic acid was achieved.

Asemota, Chris I.

270

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

271

Conducting polymers as ion transport and solid electrolyte materials  

Science.gov (United States)

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

Larmat Gonzalez, Fernando Enrique

1997-12-01

272

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

273

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

274

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

275

Electron Transfer Between Colloidal ZnO Nanocrystals  

OpenAIRE

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

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

2011-01-01

276

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)

277

DSC characterization of ion beam modifications in ion conducting PEO-salt polymers  

International Nuclear Information System (INIS)

Ion conducting polymer films have been prepared by complexing non-conducting poly-(ethylene-oxide), PEO, with x fraction of NH4ClO4 salt. Since its electrical conductivity showed a maximum at x somewhere between 0.18 and 0.19, such polymer films having 17 and 19 wt% salt, have been chosen and irradiated by 160 MeV Ne6+ beam. The films have been investigated by differential scanning calorimetry (DSC) and ac impedance spectroscopy before and after the irradiations. Irradiation-induced shift of an endotherm in our DSC indicates a rise in the melting temperature from 54.6 oC to 57.9 oC for the 19% film. Cross-linking by the Ne-irradiation making the polymer structure more rigid can explain this as well as our other observation of a decrease in electrical conductivity

278

Anomalous transmission through a periodic subwavelength hole array in heavily doped conducting polymer films*  

Science.gov (United States)

Since Ebbesen et al. reported the phenomenon of ``anomalous transmission'' through optically thick metallic films perforated with two-dimensional (2D) subwavelength hole array, numerous studies have been carried out to explore both fundamental issues and potential device applications. So far, studies on ``anomalous transmission'' were carried out using metals and semiconductors. We report here the observation of ``anomalous transmission'' in 2D hole array on films of another, more exotic class of conductors, namely heavily-doped organic conducting polymers. Specifically, the conductivity of conducting polymers can be controlled in situ by changing doping level using an electrochemical technique, so that we could tune the transmission characteristics by applied voltage. With this goal in mind we will report the ``anomalous transmission'' spectra of conducting polymer films at various doping levels. *supported in part by ARO.

Matsui, Tatsunosuke; Valy Vardeny, Z.; Agrawal, Amit; Nahata, Ajay; Menon, Reghu

2006-03-01

279

Concomitant spin-canted antiferromagnetic ordering and proton conduction in homometallic and homoleptic coordination polymers.  

Science.gov (United States)

Two unprecedented oxonate based 1D coordination polymers with Fe(II) and Co(II) have been synthesized. A detailed magnetic investigation revealed that these complexes are the first oxonate based systems to exhibit spin canted antiferromagnetic ordering at low temperatures. Proton conductivity studies of the complexes showed good proton conduction ability at elevated temperatures and under high humidity conditions. PMID:25649899

Goswami, Soumyabrata; Biswas, Soumava; Konar, Sanjit

2015-02-17

280

The material combining conducting polymer and ionic liquid: hydrogen bonding interactions between polyaniline and imidazolium salt.  

Czech Academy of Sciences Publication Activity Database

Ro?. 197, November (2014), s. 168-174. ISSN 0379-6779 R&D Projects: GA ?R(CZ) GA13-08944S Institutional support: RVO:61389013 Keywords : conducting polymer * conductivity * imidazolium salt Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.222, year: 2013

Stejskal, Jaroslav; Dybal, Ji?í; Trchová, Miroslava

2014-01-01

281

Enhancement of electrical conductivity of ion-implanted polymer films  

International Nuclear Information System (INIS)

The electrical conductivity of ion-implanted films of Nylon 66, Polypropylene (PP), Poly(tetrafluoroethylene) (Teflon) and mainly Poly (ethylene terephthalate) (PET) was determined by DC measurements at voltages up to 4500 V and compared with the corresponding values of pristine films. Measurements were made at 210C +/- 10C and 65 +/- 2% RH. The electrical conductivity of PET films implanted with F+, Ar+, or As+ ions at energies of 50 keV increases by seven orders of magnitude as the fluence increases from 1 x 1018 to 1 x 1020 ions/m2. The conductivity of films implanted with As+ was approximately one order greater than those implanted with Ar+, which in turn was approximately one-half order greater than those implanted with F+. The conductivity of the most conductive film ?1 S/m) was almost 14 orders of magnitude greater than the pristine PET film. Except for the three PET samples implanted at fluences near 1 x 1020 ions/m2 with F+, Ar+, and As+ ions, all implanted films were ohmic up to an electric field strength of 600 kV/m. The temperature dependence of the conductivity of the three PET films implanted near a fluence of 1 x 1020 ions/m2 was measured over the range of 80 K < T < 300 K

282

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

283

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

International Nuclear Information System (INIS)

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

284

Transistor Properties of Novel Organic Conducting Polymers Bearing Tetrathiafulvalene Units in the Backbone  

Science.gov (United States)

The organic field-effect transistor (OFET) properties of conducting polymers bearing a tetrathiafulvalene (TTF) unit in the backbone whose termini are capped with functional groups were investigated. The OFET devices were fabricated by a solution process under various fabrication conditions. All the devices showed typical p-type semiconducting behavior as expected from the electron-donating properties of TTF derivatives. Cast films exhibited higher field-effect mobilities than spin-coated films. Surface treatment with organic silane molecules produced no noticeable effects. When using thioacetyl-capped polymer, treatment of the OFET device in an ammonia atmosphere resulted in a field-effect mobility one order of magnitude higher than that of the pristine film. By contrast, there was no such enhancement with ethyl acetate-capped polymer. Atomic force microscopy observations revealed that the ammonia treatment promoted the ordering of the polymer chain, which resulted in improved electronic conduction.

Kashimura, Yoshiaki; Goto, Touichiro; Nakashima, Hiroshi; Furukawa, Kazuaki; Wang, Erjing; Li, Hongxiang; Hu, Wenping; Torimitsu, Keiichi

2010-01-01

285

Single lithium-ion conducting polymer electrolytes based on poly[(4-styrenesulfonyl)(trifluoromethanesulfonyl)imide] anions  

International Nuclear Information System (INIS)

Highlights: ? Single lithium-ion conducting polymer electrolytes based on highly delocalized polyanions are prepared. ? Phase behavior and transport properties are measured. ? They show high lithium ion transference number approaching unity. ? They show high ionic conductivity at room temperature. - Abstract: New single lithium-ion conducting polymer electrolytes are prepared by a copolymerization of the two monomers, lithium (4-styrenesulfonyl)(trifluoromethanesulfonyl)imide (LiSTFSI) and methoxy-polyethylene glycol acrylate (MPEGA, CH2=CHCO2-(CH2CH2O)n-CH3, n = 8) in various monomer ratios. The structures and compositions of the prepared lithium poly[(4-styrenesulfonyl)(trifluoromethanesulfonyl) imide-co-methoxy-polyethylene glycol acrylate] (Li[PSTFSI-co-MPEGA]) copolymers are characterized by 1H and 19F NMR, and gel permeation chromatography (GPC). For comparison, the corresponding blended polymer electrolytes comprising lithium poly[(4-styrenesulfonyl) (trifluoromethanesulfonyl)imide] (LiPSTFSI) and poly(ethylene oxide) (PEO) are also prepared and characterized. The fundamental properties of these two types of lithium-ion conducting polymer electrolytes are comparatively studied, in terms of phase transitions, thermal stability, XRD, ionic conductivities, lithium-ion transference numbers (tLi+), and electrochemical stabilities. Both types of the polymer electrolytes are thermally stable up to 300 °C. While both types of polymer electrolytes exhibit single lithium-ion conducting behavior with tLi+ > 0.9, the solid-state ionic conductivities of the Li[PSTFSI-co-MPEGA] copolymer electrolytes are all higher by 1–3 orders in magnitude than those of the blended ones, irrespective of the concentration of lithium ions. The highest ionic conductivities for the copolymer electrolytes are 7.6 × 10?6 S cm?1 at 25 °C and reach 10?4 S cm?1 at 60 °C, which are obtained at the ethylene oxide (EO) unit/Li+ ratio of 20.5

286

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

287

Effective Thermal Conductivity of Polymer Composites Using Local Fractal Techniques  

Directory of Open Access Journals (Sweden)

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

Rajpal Singh Bhoopal,

2013-02-01

288

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

289

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

290

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

291

Simple Approach to Hybrid Polymer/Porous Metal Oxide Solar Cells from Solution-Processed ZnO Nanocrystals  

OpenAIRE

This work is devoted to the development of hybrid bulk heterojunction solar cells based on porous zinc oxide (ZnO) electrodes and poly(3-hexylthiophene) (P3HT), using simple synthesis procedures and deposition techniques. Starting from ZnO nanocrystals with well-controlled properties, porous ZnO electrodes of suitable porosity are deposited by spin-coating, varying the main experimental parameters such as composition of the initial ZnO formulation and choice of the organic ligand. Significant...

Boucle, J.; Snaith, Hj; Greenham, Nc

2010-01-01

292

Hybrid polymer:colloidal nanoparticle photovoltaic cells incorporating a solution-processed, multi-functioned ZnO nanocrystal layer  

Science.gov (United States)

We report significant improvement in both the power conversion efficiency and the environmental stability of solution-processed hybrid organic-inorganic solar cells by including a solution-processed ZnO nanocrystal layer between the photoactive layer and the cathode. For devices based on blends of poly(3-hexylthiophene) (P3HT) and mostly-spherical CdSe nanocrystals, incorporation of the ZnO layer leads to an up to 70% increase in the power conversion efficiency. Compared to only a few hours of shelf lifetime for unencapsulated devices with the metal cathode directly deposited on the hybrid active layer, devices with the ZnO layer can retain approximately 70% of the original efficiency when they are exposed to the laboratory ambient without encapsulation for more than two months. We attribute the function of this ZnO nanocrystal layer to a combination of optical, electronic, morphological, and chemical effects, including blocking leakage of photogenerated holes to the cathode, optimizing the optical intensity profile in the hybrid active layer, minimizing recombination or quenching of photogenerated excitons and charge carriers, significantly reducing the transport rate of oxygen and water molecules to the active layer and reducing degradation/oxidation of any low work function layer at the cathode interface.

Yang, Jihua; Qian, Lei; Zhou, Renjia; Zheng, Ying; Tang, Aiwei; Holloway, Paul H.; Xue, Jiangeng

2012-02-01

293

Structure-conductivity studies in polymer electrolytes containing multivalent cations  

CERN Document Server

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

Aziz, M

1996-01-01

294

Gamma Radiation Induced Preparation of Functional Conducting Polymer Hollow Spheres  

International Nuclear Information System (INIS)

New materials are sought for applications in many of the emerging fields that include catalysis, sensors, biomedical, optics and electronic application. With the advent of nanotechnology, innovative materials with novel properties are being synthesized towards target applications. Changing the sizes of particles, chemical, optical, and mechanical properties of the materials can often be tailored according to the specific needs of the application. Nanocrystalline, nanoparticles, nanocapsules, nanoporous materials, nanofibers, nanowires, fullerenes, nanotubes, nanosprings, nanobelts, dendrimers and nanospheres, ets, are few of the nanostructured materials. The examples of nanostructured materials include semiconducting nanowire quantum dots for gas sensing and self-assembled flower-like architectures. Self-assembly of nanoparticles can result in specific structures with unique and useful electronic, optical, and magnetic properties. Self or induced assemby of simple nanoparticles and rods could result into complex geometries, such as nanoflowers, binary superlattices, optical grating. Over the past decade, hollow spherical nanomaterials have received considerable attention due to their interesting properties such as low density, high surface area and good permeation. Various methods like solvothermal, self-assembly, sonochemical, solvent evaporation, chemical vapor deposition, microwave-assisted aqueous hydrothermal and electrochemical are being pursued for the production of hollow spherical materials. Polymer capsules and hollow spheres have increasingly received interest because of their large surface area and potential applications in catalysis, controlled delivery, artificial cells, light fillers and photonics

295

Thermal Conduction in Aligned Carbon Nanotube–Polymer Nanocomposites with High Packing Density  

OpenAIRE

Nanostructured composites containing aligned carbon nanotubes (CNTs) are very promising as interface materials for electronic systems and thermoelectric power generators. We report the first data for the thermal conductivity of densified, aligned multiwall CNT nanocomposite films for a range of CNT volume fractions. A 1 vol % CNT composite more than doubles the thermal conductivity of the base polymer. Denser arrays (17 vol % CNTs) enhance the thermal conductivity by as much as a factor of 18...

Marconnet, Amy M.; Yamamoto, Namiko; Panzer, Matthew A.; Wardle, Brian L.; Goodson, Kenneth E.

2011-01-01

296

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

297

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1993-03-22

298

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

299

Individually addressable crystalline conducting polymer nanowires in a microelectrode sensor array  

International Nuclear Information System (INIS)

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

300

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

301

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

International Nuclear Information System (INIS)

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

302

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

303

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

304

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

International Nuclear Information System (INIS)

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

305

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

Science.gov (United States)

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

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

2011-12-01

306

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

International Nuclear Information System (INIS)

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

307

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

308

Thermal Conductivity of Polymer/Nano-filler Blends  

Science.gov (United States)

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

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

2006-01-01

309

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

Science.gov (United States)

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

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

1988-01-01

310

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

311

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

312

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

313

Investigation into radiation electric conductivity of some polymers  

International Nuclear Information System (INIS)

Radiation electric conductivity (?sub(r)) of technical films made of high-pressure polyethylene, polypropylene polyethyleneterephtalate (PETP), polytetrafluoroethylene (PTPE), polyvinylchloride, polysterene (PS) is studied. The effect of low doses (up to 10 kGy) of preliminary 60Co ? irradiation is estimated. PETP samples demonstrate a reversible effect of ?sub(p) absolute value reduction after preliminary irradiation. With a temperature increase the dose effect completely disappears. PTPE samples preliminarily irradiated with . a dose of 8 kGy in vacuum after scoring them in air exhibit a decrease in ?sub(r). Immediately after a PS preliminary irradiation a reversible decrease in ?sub(r) is observed

314

Graphene-polyethylenedioxythiophene conducting polymer nanocomposite based supercapacitor  

Energy Technology Data Exchange (ETDEWEB)

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

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

2011-10-30

315

Optimizing Efficiency in Conducting Polymer/Single-walled Carbon Nanotube Hybrids for Organic Photovoltaics  

Science.gov (United States)

Several unique properties of single-walled carbon nanotubes (SWCNTs) have motivated their investigation as potential replacements for fullerene derivatives as the acceptor phase of organic photovoltaic (OPV) devices. Although replacement of the ubiquitous fullerene acceptors by SWCNTs in OPV devices has shown limited success thus far, better understanding of charge transfer between SWCNTs and conjugated polymers has promoted its viability. We provide experimental evidence that m-SWNTs limit the generation efficiency and lifetime of the charge-separated state in these composites. We also probe the photo-carrier generation and decay dynamics in poly(3-hexylthiophene) (P3HT) paired with a broad diameter range of SWCNTs. We witness electron transfer from the polymer to SWCNT and selective hole transfer from the SWCNT to polymer by varying the nanotube HOMO via its diameter. We finally extend our investigation to additional semi-conducting polymers that have contributed to high OPV efficiencies, pBTTT and PCDTBT.

Holt, Josh; Prehn, Fritz; Heeney, Martin; Kopidakis, Nikos; Rumbles, Garry; Blackburn, Jeffrey

2012-02-01

316

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)

317

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

Directory of Open Access Journals (Sweden)

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

Mohammad Reza Ganjali

2008-04-01

318

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

319

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

International Nuclear Information System (INIS)

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

320

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

Science.gov (United States)

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

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

2013-06-01

321

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.

322

Conductivity studies of LiCF3SO3 doped PVA: PVdF blend polymer electrolyte  

International Nuclear Information System (INIS)

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

323

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

324

Conducting polymer-doped polyprrrole as an effective cathode catalyst for Li-O2 batteries  

International Nuclear Information System (INIS)

Graphical abstract: - Highlights: • Doped polypyrrole as cathode catalysts for Li-O2 batteries. • Polypyrrole has an excellent redox capability to activate oxygen reduction. • Chloride doped polypyrrole demonstrated an improved catalytic performance in Li-O2 batteries. - Abstract: Polypyrrole conducting polymers with different dopants have been synthesized and applied as the cathode catalyst in Li-O2 batteries. Polypyrrole polymers exhibited an effective catalytic activity towards oxygen reduction in lithium oxygen batteries. It was discovered that dopant significantly influenced the electrochemical performance of polypyrrole. The polypyrrole doped with Cl? demonstrated higher capacity and more stable cyclability than that doped with ClO4?. Polypyrrole conducting polymers also exhibited higher capacity and better cycling performance than that of carbon black catalysts

325

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

326

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

327

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

Scientific Electronic Library Online (English)

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 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.

328

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

Science.gov (United States)

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

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

2014-02-26

329

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2006-06-01

330

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

331

Conducting polymer and ionic liquid: improved thermal stability of the material - a spectroscopic study.  

Czech Academy of Sciences Publication Activity Database

Ro?. 109, November (2014), s. 27-32. ISSN 0141-3910 R&D Projects: GA ?R GAP205/12/0911 Institutional support: RVO:61389013 Keywords : polyaniline * conducting polymer * ionic liquid Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.633, year: 2013

Trchová, Miroslava; Šed?nková, Ivana; Morávková, Zuzana; Stejskal, Jaroslav

2014-01-01

332

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)

333

Conducting instant adhesives by grafting of silane polymer onto expanded graphite.  

Science.gov (United States)

A "grafting to" methodology for the attachment of a silane based polymer (SG) onto functionalized graphitic platelets is demonstrated. The siloxy end groups of the modifier were further cross-linked without addition of any external curative. These sterically stabilized nanoplatelets with a high grafting density ensured complete screening of the attractive interparticle interactions. As a result, a better dispersion of platelets was observed compared to the physically mixed platelets in the polymer matrix (SUG). The larger size of the polymer tethered graphitic particles and the greater extent of heat liberated due to grafting resulted in a higher enthalpic contribution in the case of SG compared to SUG. This makes the formation of SG thermodynamically more favorable compared to SUG. Presence of a hierarchical spatial arrangement with a good dispersion of graphitic platelets was observed within the siloxane matrix in the case of SG compared to SUG. The nanoparticle tethered composite generated exhibited an "instant" conducting adhesive behavior. The adhesive properties of the SG were found to be increased due to grafting of graphitic platelets when compared with the neat polymer. Further, SG exhibited a conductive character whereas the neat polymer and SUG demonstrated an insulating character. PMID:25184907

Mondal, Titash; Bhowmick, Anil K; Krishnamoorti, Ramanan

2014-09-24

334

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

International Nuclear Information System (INIS)

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

335

Criteria for differentiating electron and ion conductivity in high-ohmic polymer solids  

International Nuclear Information System (INIS)

The differentiation of electron and ion charge carriers is of principal importance for explaining the electrical properties of high polymer solids. Experimental methods allowing the differentiation between electron and ion charge carrier transport are summarized and estimated, particularly mass transport (mass spectroscopy, neutron activation analysis, and tracer technique) as direct methods as well as 'internal' electrical effects (d.c. characteristics and dielectric measurements) and 'external' electrical effects (electrochemical cell, electrode conditions, pressure dependence of conductivity, photoelectric effects) as indirect methods. The results obtained with various high-ohmic polymer solids are summarized and discussed. (author)

336

Ionic conductivity in PEO-KOH polymer electrolytes and electrochemical cell performance  

Science.gov (United States)

Polyethylene oxide (PEO) and potassium hydroxide (KOH) alkaline solid polymer electrolytes were prepared by the solution cast technique. The PEO:KOH wt% ratio in the alkaline solid polymer electrolyte system which exhibits the highest room temperature conductivity is 60:40. The conductivity was 3.10 × 10-5 S cm-1. X-ray diffraction (XRD) and electrochemical impedance spectroscopy (EIS) were used to study the characteristics of the PEO polymer electrolyte films. The Rice and Roth model was used to evaluate the number density of charge carriers. Knowing the number density of charge carriers enabled the mobility and diffusion coefficient to be calculated. An all solid-state Ni(OH)2/MH rechargeable metal hydride cell has been fabricated using the highest conducting PEO-KOH alkaline solid polymer electrolyte. The cell was charged at a constant current of 2 mA and discharged at 0.5 mA. The discharge characteristics improved upon cycling and the plateau voltage maintained above 1.3 V for more than 2 hours during the 16th cycle.

Hassan, M. F.; Arof, A. K.

2005-10-01

337

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

International Nuclear Information System (INIS)

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

338

Fabrication and Testing of a Bi-Conductive Polymer Membrane Fuel Cell  

Science.gov (United States)

This paper reports the fabrication process and testing of a bi-conductive polymer membrane (BCPM) fuel cell that integrates lateral current collectors on both sides with an ionic conductive path through the membrane. The new membrane shows major advantages over standard Nafion® membranes used in Polymer Electrolyte Fuel Cells (PEMFCs). In addition to being mechanically stable when wet, the flexible BCPM integrates efficient thin film current collectors (ICCs) on an ionic conductive membrane with a high active area ratio. Also, ICCs leave all the surface of the electrode free to eventually integrate a more efficient water and gas management system than traditional gas diffusion layers. Moreover, the fabricated membrane has shown superior volumetric power density than standard PEMFC (0.76 vs 0.47 mW/cm2?m).

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

2014-11-01

339

An insight into the mechanism of charge-transfer of hybrid polymer:ternary/quaternary chalcopyrite colloidal nanocrystals  

OpenAIRE

In this work, we have demonstrated the structural and optoelectronic properties of the surface of ternary/quaternary (CISe/CIGSe/CZTSe) chalcopyrite nanocrystallites passivated by tri-n-octylphosphine-oxide (TOPO) and tri-n-octylphosphine (TOP) and compared their charge transfer characteristics in the respective polymer: chalcopyrite nanocomposites by dispersing them in poly(3-hexylthiophene) polymer. It has been found that CZTSe nanocrystallites due to their high crystallinity and well-order...

Chawla, Parul; Singh, Son; Sharma, Shailesh Narain

2014-01-01

340

Comparative studies of electric conductivity of polymers induced by low-energy electron and ?-irradiation  

International Nuclear Information System (INIS)

To compare the electron and ?-radiation effect the ? of PELP, PS, PETR and polypyromellitimide dependences on R, the electric field conductivity being E=107 V/m, and on electric field conductivity with preset dose rate are studied. It is stated that electric conductivity of the investigated polymer dielectrics induced by continuous 30-60 keV electron irradiation and 1.25 MeV ?-irradiation is independent on the irradiation form and energy but is defined by absorbed dose rate and in strong fields - also by electric field intensity

341

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

342

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

343

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

344

Peculiarities of radiation conductivity kinetics of partially-crystalline polymer dielectrics and molecular mobility  

International Nuclear Information System (INIS)

Feature of radiation conductivity kinetics of partially-crystalline polymers (polytetrafluorethylene, polyethylene of low and high density, polypropylene) at continuous action with electrons (75 keV), with dose capacity D>10 Gy/s, within temperature range 100-371 K is presence of two or more maximums under given irradiation temperatures. At temperature variation behavior of kinetics curves considerably change. With temperature increase the maximums draw off, with temperature reduction maximums disconnect and displace to side of high times and decrease by value. When temperature is rather low other one instant maximum is resolved, time of the maximum definition is t<0.1 s. Dynamics of maximums in dependence from electric field intensity and irradiation dose capacity is studied as well. It is determined, that radiation conductivity in examined polymers has at least three kinetically different stages, and to approximate by simple power function following from dispersion transport theory. Radiation conductivity of these polymers is defining by competition of jump and diffusion-controlling mechanisms of charge transport. Due to there is necessity of consideration of molecular mobility role in transfer of charge carriers at polymers radiolysis. It is defined, that radiation electric conductivity in indicated objects is caused by molecular relaxation spectrum. Molecular mobility in charge transport take place when relaxation transition frequency become larger than frequency of thermal fluctuation release of charges from traps. In this case the charge transfer is carrying out by the relay-race diffusion mechanism. When molecular mobility is frozen, radiation conductivity is defined by jump charge transport by system of small traps

345

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

Directory of Open Access Journals (Sweden)

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

S. Fakirov

2013-07-01

346

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 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. PMID:21673397

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

2011-07-01

347

Low power, lightweight vapor sensing using arrays of conducting polymer composite chemically-sensitive resistors  

Science.gov (United States)

Arrays of broadly responsive vapor detectors can be used to detect, identify, and quantify vapors and vapor mixtures. One implementation of this strategy involves the use of arrays of chemically-sensitive resistors made from conducting polymer composites. Sorption of an analyte into the polymer composite detector leads to swelling of the film material. The swelling is in turn transduced into a change in electrical resistance because the detector films consist of polymers filled with conducting particles such as carbon black. The differential sorption, and thus differential swelling, of an analyte into each polymer composite in the array produces a unique pattern for each different analyte of interest, Pattern recognition algorithms are then used to analyze the multivariate data arising from the responses of such a detector array. Chiral detector films can provide differential detection of the presence of certain chiral organic vapor analytes. Aspects of the spaceflight qualification and deployment of such a detector array, along with its performance for certain analytes of interest in manned life support applications, are reviewed and summarized in this article.

Ryan, M. A.; Lewis, N. S.

2001-01-01

348

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.

349

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

350

High ionic conductivity P(VDF-TrFE)/PEO blended polymer electrolytes for solid electrochromic devices.  

Science.gov (United States)

Solid polymer electrolytes with excellent ionic conductivity (above 10(-4) S cm(-1)), which result in high optical modulation for solid electrochromic (EC) devices are presented. The combination of a polar host matrix poly(vinylidene fluoride-trifluoroethylene) P(VDF-TrFE) and a solid plasticized of a low molecular weight poly(ethylene oxide) (PEO) (M(w)? 20,000) blended polymer electrolyte serves to enhance both the dissolution of lithium salt and the ionic transport. Calorimetric measurement shows a reduced crystallization due to a better intermixing of the polymers with small molecular weight PEO. Vibrational spectroscopy identifies the presence of free ions and ion pairs in the electrolytes with PEO of M(w)? 8000. The ionic dissolution is improved using PEO as a plasticizer when compared to liquid propylene carbonate, evidently shown in the transference number analysis. Ionic transport follows the Arrhenius equation with a low activation energy (0.16-0.2 eV), leading to high ionic conductivities. Solid electrochromic devices fabricated with the blended P(VDF-TrFE)/PEO electrolytes and polyaniline show good spectroelectrochemical performance in the visible (300-800 nm) and near-infrared (0.9-2.4 ?m) regions with a modulation up to 60% and fast switching speed of below 20 seconds. The successful introduction of the solid polymer electrolytes with its best harnessed qualities helps to expedite the application of various electrochemical devices. PMID:21706071

Nguyen, Chien A; Xiong, Shanxin; Ma, Jan; Lu, Xuehong; Lee, Pooi See

2011-08-01

351

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

DEFF Research Database (Denmark)

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

Lind, Johan Ulrik

2012-01-01

352

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

International Nuclear Information System (INIS)

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

353

Investigations on the Mechanical Properties of Conducting Polymer Coating-Substrate Structures and Their Influencing Factors  

Directory of Open Access Journals (Sweden)

Full Text Available This review covers recent advances and work on the microstructure features, mechanical properties and cracking processes of conducting polymer film/coatingsubstrate structures under different testing conditions. An attempt is made to characterize and quantify the relationships between mechanical properties and microstructure features. In addition, the film cracking mechanism on the micro scale and some influencing factors that play a significant role in the service of the film-substrate structure are presented. These investigations cover the conducting polymer film/coating nucleation process, microstructure-fracture characterization, translation of brittle-ductile fractures, and cracking processes near the largest inherent macromolecule defects under thermal-mechanical loadings, and were carried out using in situ scanning electron microscopy (SEM observations, as a novel method for evaluation of interface strength and critical failure stress.

Xin Hua

2009-12-01

354

Electrosynthesis and absorbance spectra of TiO{sub 2} nanoparticles dispersed in the conductive polymer  

Energy Technology Data Exchange (ETDEWEB)

Poly ortho aminophenol (POAP)/nanocrystalline TiO{sub 2} composite were electrodeposited from through cyclic voltammetry scans to afford conductive polymer/TiO{sub 2} nanocomposite. Polymerization of ortho aminophenol (OAP) proceeded after ultrasonic irradiation of nanocrystalline TiO{sub 2}. The aggregation of nano TiO{sub 2} can be reduced under ultrasonic irradiation, and the nanoparticles can be redispersed in the aqueous solution. The presence of nanocrystalline TiO{sub 2} strengthens the UV absorption of POAP and leads to a blue shift of the ?-polaron absorption of POAP. Experimental absorbance spectra of TiO{sub 2}/conductive polymer nanocomposite compared with results that obtained from the Maxwell–Garnett theory (MGT).

Ehsani, Ali, E-mail: a.ehsani@qom.ac.ir [Department of Chemistry, Faculty of Science, University of Qom, Qom (Iran, Islamic Republic of); Babaei, Ferydon [Department of Physics, Faculty of Science, University of Qom, Qom (Iran, Islamic Republic of); Nasrollahzadeh, Mahmoud [Department of Chemistry, Faculty of Science, University of Qom, Qom (Iran, Islamic Republic of)

2013-10-15

355

Current-dependent anisotropic conductivity of locally assembled silver nanoparticles in hybrid polymer films.  

Science.gov (United States)

The electrical behaviour of hybrid poly(ethylene terephthalate) films containing localised, percolating networks of silver nanoparticles separated by pure polymer is studied. The films resemble an array of parallel wires in the submicron range and, thus, exhibit anisotropic conductivity. In the high-conductivity direction at low amplitudes, the films show Ohmic behaviour, while at moderate voltage, non-linearity and a decreasing resistance is observed. The samples were found to heat up during the measurements and the deviation from Ohm's law coincides with the Tg of the polymer. Microstructural analysis of the samples revealed an irreversible agglomeration of the particles at moderate voltages leading to the formation of filaments with higher metallic character than the random particle network. PMID:20843521

Goel, Pooja; Vinokur, Rostislav; Weichold, Oliver

2010-12-15

356

Electrosynthesis and absorbance spectra of TiO2 nanoparticles dispersed in the conductive polymer  

International Nuclear Information System (INIS)

Poly ortho aminophenol (POAP)/nanocrystalline TiO2 composite were electrodeposited from through cyclic voltammetry scans to afford conductive polymer/TiO2 nanocomposite. Polymerization of ortho aminophenol (OAP) proceeded after ultrasonic irradiation of nanocrystalline TiO2. The aggregation of nano TiO2 can be reduced under ultrasonic irradiation, and the nanoparticles can be redispersed in the aqueous solution. The presence of nanocrystalline TiO2 strengthens the UV absorption of POAP and leads to a blue shift of the ?-polaron absorption of POAP. Experimental absorbance spectra of TiO2/conductive polymer nanocomposite compared with results that obtained from the Maxwell–Garnett theory (MGT).

357

All-solid-state ion-selective silicone rubber membrane electrodes with a new conducting polymer  

Energy Technology Data Exchange (ETDEWEB)

New conducting polymers containing heterocyclic rings with carbazole, ethylene dioxythiophene (EDOT) and benzobisthiazole were synthesized and the characterized by using organic spectroscopic methods. Potentiometric ion-selective membrane electrodes (ISMEs) have been extensively used for ion analysis in clinical, environmental, and industrial fields owing to their wide response range (4 to 7 orders of magnitude), no effect of sample turbidity, fast response time, and ease of miniaturization. Considerable attention has been given to alternative use of room-temperature vulcanizing (RTV)-type silicone rubber (SR) owing to its strong adhesion and high thermal durability. Unfortunately, the high membrane resistance of SR-based ion-selective membranes (ISMs) (2 to 3 higher orders of magnitude compared to those of poly(vinyl chloride)(PVC)-based ones) has significantly restricted their application. Herein, we demonstrate a new method to reduce the membrane resistance via addition of a new conducting polymer into the SR-based ISMs.

Park, Eun Rang; Chung, Yeon Joon; Hwang, Sun Woo [Kwangwoon University, Seoul (Korea, Republic of); and others

2012-03-15

358

Electrochemical and Optical Investigation of Conductive Polymer and MWCNT Nanocomposite Film  

Scientific Electronic Library Online (English)

Full Text Available Composites of multi-walled carbon nanotubes (MWCNT) and conductive polymer with good uniformity were prepared by electropolymerization. Molecular modeling calculations were carried out for electroactive monomer (OAP) polymerization with density functional theory (DFT) level using 6-311G(d,p) basis s [...] et for all atoms and Gaussian 03 program package. The reflectance and transmittance amplitudes of the composite were obtained, using the continuity of the tangential components of electrical and magnetic fields at interfaces and solving the algebraic matrix equation. The calculated absorbance spectra as a function of wavelength for MWCNTs dispersed in the conductive polymer are depicted. Band gap of the p-type semiconducting film was obtained from the plot of (?hv)2 vs. photon energy.

Ali, Ehsani; Ferydon, Babaei; Hossein, Mostaanzadeh.

2015-02-01

359

All-solid-state ion-selective silicone rubber membrane electrodes with a new conducting polymer  

International Nuclear Information System (INIS)

New conducting polymers containing heterocyclic rings with carbazole, ethylene dioxythiophene (EDOT) and benzobisthiazole were synthesized and the characterized by using organic spectroscopic methods. Potentiometric ion-selective membrane electrodes (ISMEs) have been extensively used for ion analysis in clinical, environmental, and industrial fields owing to their wide response range (4 to 7 orders of magnitude), no effect of sample turbidity, fast response time, and ease of miniaturization. Considerable attention has been given to alternative use of room-temperature vulcanizing (RTV)-type silicone rubber (SR) owing to its strong adhesion and high thermal durability. Unfortunately, the high membrane resistance of SR-based ion-selective membranes (ISMs) (2 to 3 higher orders of magnitude compared to those of poly(vinyl chloride)(PVC)-based ones) has significantly restricted their application. Herein, we demonstrate a new method to reduce the membrane resistance via addition of a new conducting polymer into the SR-based ISMs.

360

Investigations on the Mechanical Properties of Conducting Polymer Coating-Substrate Structures and Their Influencing Factors  

OpenAIRE

This review covers recent advances and work on the microstructure features, mechanical properties and cracking processes of conducting polymer film/coating- substrate structures under different testing conditions. An attempt is made to characterize and quantify the relationships between mechanical properties and microstructure features. In addition, the film cracking mechanism on the micro scale and some influencing factors that play a significant role in the service of the film-substrate str...

Xin Hua; Hua-Ping Tang; Xu-Dong Li; Xi-Shu Wang

2009-01-01

361

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

Energy Technology Data Exchange (ETDEWEB)

We investigated the effects of PEG-borate ester on the ionic conductivity and transport number of lithium ions in polymer electrolytes with Li-salt, such as LiN(CF{sub 3}SO{sub 2}){sub 2}, LiClO{sub 4} or LiCF{sub 3}SO{sub 3}. The ionic conductivity of the polymer electrolyte with LiN(CF{sub 3}SO{sub 2}){sub 2} was found to be higher than those of the electrolytes with LiClO{sub 4} or LiCF{sub 3}SO{sub 3}. This result is mainly concerned with mobility of ions, which is indicated by the comparison of glass transition temperatures of the polymer electrolytes. On the other hand, the transport numbers of lithium ions in the polymer electrolytes with LiClO{sub 4} or LiCF{sub 3}SO{sub 3} were higher than those of the electrolyte with LiN(CF{sub 3}SO{sub 3}){sub 2}. Furthermore, the conductivities of lithium ions calculated by multiplying the ionic conductivity measured by ac impedance with transport number of lithium ions were also found to be higher than that of the electrolytes with LiN(CF{sub 3}SO{sub 2}). These results indicate that the PEG-borate ester acts as Lewis acid and interacts with CF{sub 3}SO{sub 3}{sup -} or ClO{sub 4}{sup -} more effectively compared with N(CF{sub 3}SO{sub 2}){sub 2}{sup -}, leading to improved dissociation of Li-salts and transport number of lithium ions. (author)

Kato, Y.; Ikuta, H.; Uchimoto, Y.; Wakihara, M. [Tokyo Institute of Technology (Japan). Graduate School of Science and Engineering, Department of Applied Chemistry; Yokoyama, S.; Yabe, T. [NOF Corporation, Kawasaki, Kanagawa (Japan). Oleochemicals Research Lab., Alkylene Oxide Group 2

2004-11-30

362

Novel in situ electrochemical deposition of platinum nanoparticles by sinusoïdal voltages on conducting polymer films.  

OpenAIRE

Platinum (Pt) nanoparticles were successfully electrodeposited in situ on an organic conductive polymer, poly(3,4-ethylenedioxythiophene) (PEDOT), using for the first time sinusoidal voltages of various frequencies in a chloroplatinic acid solution. The organic PEDOT matrix was electrodeposited on Pt electrode chips. The Pt electrode chips consist of a 150 nm Pt layer deposited on 100-oriented standard 3'' silicon wafers. The cyclic voltammograms of the PEDOT-Pt-nanoparticles composite materi...

Lupun, Stelian; Lakard, Boris; Hihn, Jean-yves; Dejeu, Je?ro?me

2012-01-01

363

Detection of Off-Flavor in Catfish Using a Conducting Polymer Electronic-Nose Technology  

OpenAIRE

The Aromascan A32S conducting polymer electronic nose was evaluated for the capability of detecting the presence of off-flavor malodorous compounds in catfish meat fillets to assess meat quality for potential merchantability. Sensor array outputs indicated that the aroma profiles of good-flavor (on-flavor) and off-flavor fillets were strongly different as confirmed by a Principal Component Analysis (PCA) and a Quality Factor value (QF > 7.9) indicating a significant difference at (P < 0...

Wilson, Alphus D.; Oberle, Charisse S.; Oberle, Daniel F.

2013-01-01

364

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

Science.gov (United States)

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

Dmitrenko, V. E.; Lubentsov, B. Z.; Yevdokimenko, S. G.; Lisyansky, I. I.; Soldatenko, V. A.

365

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

OpenAIRE

The strikingly different charge transport behaviors in nanocomposites of multiwall carbon nanotubes (MWNTs) and conducting polymer polyethylene dioxythiophene - 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 assembly of elongated PEDOT-PSS globules on the walls of nanotubes, coating them partially thereby limiting the interaction between th...

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

2011-01-01

366

Dextrin and conducting polymer containing biocomposites : properties and behavior as cellular matrix  

OpenAIRE

Both ?-cyclodextrin and linear dextrin are used to prepare biocomposites with poly(3,4- ethylenedioxythiophene). Materials are prepared electrochemically in aqueous solution. Comparison with the pure polymer indicates that the electroactivity and electrostability decrease with the incorporation of the dextrins while the electrical conductivity is retained. The different properties of the two biocomposites suggest that the linear dextrin is mainly located at the surface, whereas the ...

Dias, B. Teixeira; Del Valle, L. J.; Estrany, F.; Mano, J. F.; Reis, R. L.; Aleman, C.

2012-01-01

367

How the type of input function affects the dynamic response of conducting polymer actuators  

Science.gov (United States)

There has been a growing interest in smart actuators typified by conducting polymer actuators, especially in their (i) fabrication, modeling and control with minimum external data and (ii) applications in bio-inspired devices, robotics and mechatronics. Their control is a challenging research problem due to the complex and nonlinear properties of these actuators, which cannot be predicted accurately. Based on an input-shaping technique, we propose a new method to improve the conducting polymer actuators’ command-following ability, while minimizing their electric power consumption. We applied four input functions with smooth characteristics to a trilayer conducting polymer actuator to experimentally evaluate its command-following ability under an open-loop control strategy and a simulated feedback control strategy, and, more importantly, to quantify how the type of input function affects the dynamic response of this class of actuators. We have found that the four smooth inputs consume less electrical power than sharp inputs such as a step input with discontinuous higher-order derivatives. We also obtained an improved transient response performance from the smooth inputs, especially under the simulated feedback control strategy, which we have proposed previously [X Xiang, R Mutlu, G Alici, and W Li, 2014 “Control of conducting polymer actuators without physical feedback: simulated feedback control approach with particle swarm optimization’, Journal of Smart Materials and Structure, 23]. The idea of using a smooth input command, which results in lower power consumption and better control performance, can be extended to other smart actuators. Consuming less electrical energy or power will have a direct effect on enhancing the operational life of these actuators.

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

2014-10-01

368

Change in electrical conductivity of polymers with conjugated bonds by means of H2+ ion implantation  

International Nuclear Information System (INIS)

The change in electrical conductivity of polymers with conjugated bonds such as transpolyacetylene, polyparaphenylene, polypyrole, polyaniline, and structures with conjugated bonds obtained by chemical modification of polyvinylchloride and polytetrafluoroethylene was investigated during and after H2+ ion implantation (300 keV at RT). The resistance (R) of implanted samples with conjugated bonds decreases as the fluence increases and a sharp decrease in R appears at a fluence of about 5 x 1016 protons/cm2

369

Formation of conductive networks with both segregated and double-percolated characteristic in conductive polymer composites with balanced properties.  

Science.gov (United States)

Morphological control of conductive networks involves the construction of segregated or double-percolated conductive networks is often reported to reduce the electrical percolation threshold of conductive polymer composites (CPCs) for better balance among electrical conductivity, mechanical properties, and filler content. Herein, the construction of conductive networks with both segregated and double-percolated characteristics is achieved based on polypropylene (PP)/polyethylene (PE) and multi-wall carbon nanotubes (CNTs). CNTs were firstly dispersed in PE; then PE/CNTs were compounded with PP particles well below the melting temperature of PP. It is observed that the percolation threshold (pc) decreases with increasing PP particle size (size 3.6 mm, pc=0.08 wt %), which agrees with previous theoretical prediction and experiment in much smaller particle size range. To further study this, the amount of CNTs in PE is varied. It is shown that the degree of PE/CNTs coating on PP particles varies with CNTs as well as PE content in these composites, and have significant influence on the final electrical property. Furthermore, a model combines classical percolation theory and model for segregated network has been proposed to analyze the effect of particle size, degree of coating and thickness of coating on the percolation behavior of these CPCs. In such a model the percolation of CNTs in PE phase as well as PENT phase in the segregated structure can be described. Overall, through such method, a much better balance among mechanical property, conductivity, and filler content is achieved in these CPCs comparing with the results in literature. PMID:24745303

Zhang, Shuangmei; Deng, Hua; Zhang, Qin; Fu, Qiang

2014-05-14

370

Transparent conductive-polymer strain sensors for touch input sheets of flexible displays  

International Nuclear Information System (INIS)

A transparent conductive polymer-based strain-sensor array, designed especially for touch input sheets of flexible displays, was developed. A transparent conductive polymer, namely poly(3, 4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS), was utilized owing to its strength under repeated mechanical bending. PEDOT:PSS strain sensors with a thickness of 130 nm exhibited light transmittance of 92%, which is the same as the transmittance of ITO electrodes widely used in flat panel displays. We demonstrated that the sensor array on a flexible sheet was able to sustain mechanical bending 300 times at a bending radius of 5 mm. The strain sensor shows a gauge factor of 5.2. The touch point on a flexible sheet could be detected from histograms of the outputs of the strain sensors when the sheet was pushed with an input force of 5 N. The touch input could be detected on the flexible sheet with a curved surface (radius of curvature of 20 mm). These results show that the developed transparent conductive polymer-based strain-sensor array is applicable to touch input sheets of mechanically bendable displays.

371

An insight into the mechanism of charge-transfer of hybrid polymer:ternary/quaternary chalcopyrite colloidal nanocrystals.  

Science.gov (United States)

In this work, we have demonstrated the structural and optoelectronic properties of the surface of ternary/quaternary (CISe/CIGSe/CZTSe) chalcopyrite nanocrystallites passivated by tri-n-octylphosphine-oxide (TOPO) and tri-n-octylphosphine (TOP) and compared their charge transfer characteristics in the respective polymer: chalcopyrite nanocomposites by dispersing them in poly(3-hexylthiophene) polymer. It has been found that CZTSe nanocrystallites due to their high crystallinity and well-ordered 3-dimensional network in its pristine form exhibit a higher steric- and photo-stability, resistance against coagulation and homogeneity compared to the CISe and CIGSe counterparts. Moreover, CZTSe nanocrystallites display efficient photoluminescence quenching as evident from the high value of the Stern-Volmer quenching constant (K SV) and eventually higher charge transfer efficiency in their respective polymer P3HT:CZTSe composites. We modelled the dependency of the charge transfer from the donor and the charge separation mechanism across the donor-acceptor interface from the extent of crystallinity of the chalcopyrite semiconductors (CISe/CIGSe/CZTSe). Quaternary CZTSe chalcopyrites with their high crystallinity and controlled morphology in conjunction with regioregular P3HT polymer is an attractive candidate for hybrid solar cells applications. PMID:25161859

Chawla, Parul; Singh, Son; Sharma, Shailesh Narain

2014-01-01

372

Photorefractivity in a polymeric composite photosensitized with NiS nanocrystals  

International Nuclear Information System (INIS)

The photorefractive performance of a polymeric composite photosensitized through the inclusion of NiS nanocrystals is described. The nanocrystals were characterized using visible-absorption spectroscopy, energy-dispersive x-ray spectroscopy, and transmission electron microscopy. We further demonstrate the ability to enhance various aspects of the composite's photorefractive performance by performing ligand exchange on the nanocrystals prior to their incorporation into the polymer composite. This procedure resulted in a lowering of the overmodulation voltage from ?70 to ?50 V/?m without affecting the maximum diffraction efficiency of ?40%. An increase in the two-beam-coupling gain coefficient was similarly observed, increasing from 38 to 79 cm-1. The photoconductivities were used in determining the overall quantum efficiencies associated with the photorefractive devices. All experiments were conducted at 633 nm and the data represent a significant improvement in the photorefractive performance of inorganic-organic hybrid photorefractive materials.

373

Tubular array, dielectric, conductivity and electrochemical properties of biodegradable gel polymer electrolyte  

International Nuclear Information System (INIS)

Highlights: • A new finding of tubular array of 10–20 ?m in length and 1–2 ?m in thickness of gel polymer electrolyte (GPE) having 2.2 × 10?3 S cm?1 conductivity is reported. • Thermal and electrochemical characterizations of GPEs show good interaction among the polymer, plasticizer and salt. • GPE based supercapacitor demonstrates high capacitance of 186 F g?1. • Low temperature studies did not influence much on capacitance values obtained from AC impedance studies. • Charge–discharge exhibits high capacity with excellent cyclic stability and energy density. -- Abstract: A supercapacitor based on a biodegradable gel polymer electrolyte (GPE) has been fabricated using guar gum (GG) as the polymer matrix, LiClO4 as the doping salt and glycerol as the plasticizer. The scanning electron microscopy (SEM) images of the gel polymer showed an unusual tubular array type surface morphology. FTIR, DSC and TGA results of the GPE indicated good interaction between the components used. Highest ionic conductivity and lowest activation energy values were 2.2 × 10?3 S cm?1 and 0.18 eV, respectively. Dielectric studies revealed ionic behavior and good capacitance with varying frequency of the GPE system. The fabricated supercapacitor showed a maximum specific capacitance value of 186 F g?1 using cyclic voltammetry. Variation of temperature from 273 K to 293 K did not significantly influence the capacitance values obtained from AC impedance studies. Galvanostatic charge–discharge study of supercapacitor indicated that the device has good stability, high energy density and power density

374

Tubular array, dielectric, conductivity and electrochemical properties of biodegradable gel polymer electrolyte  

Energy Technology Data Exchange (ETDEWEB)

Highlights: • A new finding of tubular array of 10–20 ?m in length and 1–2 ?m in thickness of gel polymer electrolyte (GPE) having 2.2 × 10{sup ?3} S cm{sup ?1} conductivity is reported. • Thermal and electrochemical characterizations of GPEs show good interaction among the polymer, plasticizer and salt. • GPE based supercapacitor demonstrates high capacitance of 186 F g{sup ?1}. • Low temperature studies did not influence much on capacitance values obtained from AC impedance studies. • Charge–discharge exhibits high capacity with excellent cyclic stability and energy density. -- Abstract: A supercapacitor based on a biodegradable gel polymer electrolyte (GPE) has been fabricated using guar gum (GG) as the polymer matrix, LiClO{sub 4} as the doping salt and glycerol as the plasticizer. The scanning electron microscopy (SEM) images of the gel polymer showed an unusual tubular array type surface morphology. FTIR, DSC and TGA results of the GPE indicated good interaction between the components used. Highest ionic conductivity and lowest activation energy values were 2.2 × 10{sup ?3} S cm{sup ?1} and 0.18 eV, respectively. Dielectric studies revealed ionic behavior and good capacitance with varying frequency of the GPE system. The fabricated supercapacitor showed a maximum specific capacitance value of 186 F g{sup ?1} using cyclic voltammetry. Variation of temperature from 273 K to 293 K did not significantly influence the capacitance values obtained from AC impedance studies. Galvanostatic charge–discharge study of supercapacitor indicated that the device has good stability, high energy density and power density.

Sudhakar, Y.N. [Department of Chemistry, Manipal Institute of Technology, Manipal, Karnataka (India); Selvakumar, M., E-mail: chemselva78@gmail.com [Department of Chemistry, Manipal Institute of Technology, Manipal, Karnataka (India); Bhat, D. Krishna [Department of Chemistry, National Institute of Technology Karnataka, Surathkal, Mangalore (India)

2014-02-15

375

Filler geometry and interface resistance of carbon nanofibres: Key parameters in thermally conductive polymer composites  

Science.gov (United States)

The thermal conductivity of polymer composites is measured for several tubular carbon nanofillers (nanotubes, fibres, and whiskers). The highest enhancement in the thermal conductivity is observed for functionalized multiwalled carbon nanotubes (90% enhancement for 1 vol. %) and Pyrograf carbon fibres (80%). We model the experimental data using an effective thermal medium theory and determine the thermal interface resistance (RK) at the filler-matrix interface. Our results show that the geometry of the nanofibres and the interface resistance are two key factors in engineering heat transport in a composite.

Gharagozloo-Hubmann, Kati; Boden, André; Czempiel, Gregor J. F.; Firkowska, Izabela; Reich, Stephanie

2013-05-01

376

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

International Nuclear Information System (INIS)

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

377

Atomic force microscopy studies of conductive nanostructures in solid polymer electrolytes  

International Nuclear Information System (INIS)

Highlights: • Different size of conductive structure at LSC and SSC membranes. • Outer skin layer of Aquivion® membrane determined to 5 nm. • Different size of conductive areas for aromatic and Nafion-type membranes. • 2-Dimensional structure of conductive network of bulk Nafion. -- Abstract: The conductivity of three different sulfonated polymer electrolyte membranes (PEM), two perfluorinated membranes, Nafion® and Aquivion®, and JST, a non-perfluorinated aromatic block copolymer, were compared using advanced material-sensitive and conductive atomic force microscopy (AFM). All of the membranes required activation by a current flow to reach significant conductivity for the AFM analysis, indicating the existence of a highly resistive surface skin layer. The two perfluorinated sulfonic acid membranes, a membrane with long side-chains (Nafion®) and a membrane with short side-chains (Aquivion®), exhibited similar properties. A lamellar surface structure, with polymer bundles or micelles in a parallel orientation, was also found for the Aquivion® membrane. AFM high-resolution current images, performed under a continuous current flow, were used to distinguish between the conducting network and the subsurface phase distribution at the membrane surface. The connected subnets of the JST membrane were approximately 100–200 nm in size, whereas those for the perfluorinated membrane surfaces were 200–300 nm in size. The conductive areas of the Aquivion® and JST membranes exhibited larger homogeneous conducting areas, corresponding to the smaller correlation lengths of ionic phase separation. Membrane cross sections were analyzed to elucidate the structure of the bulk ionic network of the Nafion® membrane, before and after operation. The existence of extended water layers in the bulk, even before operation, was confirmed

378

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

Directory of Open Access Journals (Sweden)

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

Han Wei

2008-01-01

379

The change in dielectric constant, AC conductivity and optical band gaps of polymer electrolyte film: Gamma irradiation  

International Nuclear Information System (INIS)

The effects of gamma (?) irradiation on dielectric and optical properties of polymer electrolyte film were investigated. The dielectric constant and ac conductivity increases with ? dose. Also optical band gap decreased from 4.23 to 3.78ev after irradiation. A large dependence of the polymer properties on the irradiation dose was noticed. This suggests that there is a possibility of improving polymer electrolyte properties on gamma irradiation

380

The change in dielectric constant, AC conductivity and optical band gaps of polymer electrolyte film: Gamma irradiation  

Energy Technology Data Exchange (ETDEWEB)

The effects of gamma (?) irradiation on dielectric and optical properties of polymer electrolyte film were investigated. The dielectric constant and ac conductivity increases with ? dose. Also optical band gap decreased from 4.23 to 3.78ev after irradiation. A large dependence of the polymer properties on the irradiation dose was noticed. This suggests that there is a possibility of improving polymer electrolyte properties on gamma irradiation.

Raghu, S., E-mail: dehu2010@gmail.com; Subramanya, K., E-mail: dehu2010@gmail.com; Sharanappa, C., E-mail: dehu2010@gmail.com; Mini, V., E-mail: dehu2010@gmail.com; Archana, K., E-mail: dehu2010@gmail.com; Sanjeev, Ganesh, E-mail: dehu2010@gmail.com; Devendrappa, H., E-mail: dehu2010@gmail.com [Dept. of Physics, Mangalore University, Mangalagangothri-574199 (India)

2014-04-24

381

Pressure-induced amorphization of a dense coordination polymer and its impact on proton conductivity  

International Nuclear Information System (INIS)

The proton conductivity of a dense coordination polymer (CP) was investigated under high-pressure conditions. Impedance measurements under high pressures revealed that the proton conductivity of the CP decreased more than 1000-fold at pressures of 3–7 GPa and that the activation energy for proton conduction almost doubled compared with that at ambient pressure. A synchrotron X-ray study under high pressure identified the amorphization process of the CP during compression, which rationally explains the decrease in conductivity and increase in activation energy. This phenomenon is categorized as reversible pressure-induced amorphization of a dense CP and is regarded as a demonstration of the coupling of the mechanical and electrical properties of a CP

382

Thermal conductivity of micro- and nano- filled polymer blend composite for radiation shielding material  

International Nuclear Information System (INIS)

The thermal conductivity of boron carbide filled thermoplastic natural rubber blend composite is studied experimentally as a function of filler loading and filler size. A polymer blend of 60/ 40 NR/ HDPE was used as matrix for incorporation of particulate nano- and micro- sized B4C as filler to form the composite. As the filler loading is increased from 2-10 % wt, a reduction and increment of thermal conductivity was observed. The results show at lower filler loading, HDPE crystallinity affects the thermal conductivity up to 4 and 6 % wt of filler for nano- and micro- composite respectively. Further increase the loading do not much alter the crystallinity as the filler is distributed in continues phase of NR. The increment of filler amount in the amorphous NR causes the thermal conductivity to gradually increase which indicates the formation of interconnecting filler network structures. (Author)

383

Pressure-induced amorphization of a dense coordination polymer and its impact on proton conductivity  

Directory of Open Access Journals (Sweden)

Full Text Available The proton conductivity of a dense coordination polymer (CP was investigated under high-pressure conditions. Impedance measurements under high pressures revealed that the proton conductivity of the CP decreased more than 1000-fold at pressures of 3–7 GPa and that the activation energy for proton conduction almost doubled compared with that at ambient pressure. A synchrotron X-ray study under high pressure identified the amorphization process of the CP during compression, which rationally explains the decrease in conductivity and increase in activation energy. This phenomenon is categorized as reversible pressure-induced amorphization of a dense CP and is regarded as a demonstration of the coupling of the mechanical and electrical properties of a CP.

Daiki Umeyama

2014-12-01

384

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

Science.gov (United States)

A new method for transforming common polymers into superhydrophobic conductive surfaces, with both a high static water contact angle (approximately 160 degrees) and a low sliding angle (2.0 degrees-4.5 degrees), and a low sheet resistance on the order of 10(1)-10(3) ohms/sq is presented. A layer of multiwalled carbon nanotubes (MWNTs) is first distributed on the surface of a polymer substrate, then by a single step of pressing, the MWNTs are partially embedded inside the substrate surface and form a superhydrophobic coating with a "carpet-" or "hair"-like morphology. The infiltration of polymer melts into the porous MWNT layer follows Darcy's law, and the pressing time greatly influence the morphology and superhydrophobicity. Moreover, the coating can be electrically heated by 20-70 degrees C with a voltage as low as 4-8 V at an electric energy density below 1.6 J/cm(2) and therefore can be used for deicing applications. Hydroxylation and fluoroalkylsilane treatment can greatly improve the stability of the superhydrophobicity of MWNTs. This method is convenient and applicable to a variety of thermoplastic polymers and nonpolymer substrates coated by silicone rubber. PMID:20695606

Peng, Mao; Liao, Zhangjie; Qi, Ji; Zhou, Zhi

2010-08-17

385

Preparation and characterization of novel nanocomposites of WS{sub 2} nanotubes and polyfluorene conductive polymer  

Energy Technology Data Exchange (ETDEWEB)

Tungsten disulfide (WS{sub 2}) 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 WS{sub 2} nanotubes and polyfluorene conjugated polymer (WS{sub 2}/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 WS{sub 2} nanotubes was also evidenced by UV-Vis absorbance spectroscopy. The WS{sub 2}/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)

Di Luccio, Tiziana; Borriello, Carmela; Bruno, Annalisa; Maglione, Maria Grazia; Minarini, Carla; Nenna, Giuseppe [ENEA UTTP NANO, Centro Ricerche Portici (Italy)

2013-11-15

386

Towards TiO2-conducting polymer hybrid materials for lithium ion batteries  

International Nuclear Information System (INIS)

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

387

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2012-08-15

388

X-ray evaluation of the boundary between polymer electrolyte and platinum and carbon functionalization to conduct protons in polymer electrolyte fuel cells  

Science.gov (United States)

In polymer electrolyte fuel cells (PEFCs), it is important to secure proximate diffusion paths of reactants and electrons. One approach is to optimize the boundary between polymer electrolyte and Pt nanoparticle surface. Based on synchrotron X-ray absorption fine structure to monitor directly the status of catalysts in PEFCs, it was found that Pt sites were reduced to Pt0 by alcohols contained in polymer electrolyte dispersion solution during the preparation of cathode of PEFC. As in membrane electrolyte assembly, only the Pt sites not covered by polymer electrolyte re-oxidized to Pt2+/4+. Thus, the interface between Pt and polymer electrolyte was evaluated. The other approach is to functionalize carbon surface with sulfonate/sulfate group to conduct protons. Similar level of proton conductivity was observed in current-voltage dependence compared to using polymer electrolyte, but polymer electrolyte was advantageous to lose less voltage for activation. Based on this comparison, optimum catalyst on cathode is proposed comprising surface sulfonate/sulfate group on carbon mixed with polymer electrolyte. Further optimization of cathode catalyst is proposed to functionalize carbon with sulfonate group linked to fluorocarbon branch.

Oka, Kazuki; Ogura, Yuta; Izumi, Yasuo

2014-07-01

389

Electrical conductivity and electrostatic properties of radiationally modified polymer composites with carbon black  

Energy Technology Data Exchange (ETDEWEB)

The electro-physical surface properties of polymer composites of ultrahigh-molecular-weight polyethylene containing 5, 10 and 15 vol% carbon black filler were investigated before and after irradiation by gamma-rays of a {sup 60}Co source. Measurements of the specific surface conductivity {sigma}{sub s}, surface dissipation factor tan{delta}{sub s}, volume dissipation factor tan{delta}{sub v}, and the maximum surface potential U{sub max} after charging with positive or negative ions by dc corona discharge, were carried out at room temperature in air of 65% humidity. U{sub max} was found to have a strong dependence on irradiation dose especially at doses ranging up to 1 Mrad. Also, {sigma}{sub s} exhibits a substantial decrease of up to seven orders of magnitude at doses from 100 krad to 1 Mrad. These effects are supposedly linked with the radiationally stimulated destruction of carbon chains on the polymer composite surface. On the other hand, at doses higher than 1-2 Mrad there is an extraordinary high rise of the specific surface conductivity of the samples containing 5 vol% filler which reaches nine orders of magnitude and more. This is attributed to the formation of chains of carbon nanoclusters in the near-to-surface layer of the polymer composite. (author)

Balabanov, S. [Institute of Solid State Physics G Nadjakov, Bulgarian Academy of Sciences, Sofia (Bulgaria); Krezhov, K. [Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences, Sofia (Bulgaria)

1999-10-07

390

Electrical conductivity and electrostatic properties of radiationally modified polymer composites with carbon black  

International Nuclear Information System (INIS)

The electro-physical surface properties of polymer composites of ultrahigh-molecular-weight polyethylene containing 5, 10 and 15 vol% carbon black filler were investigated before and after irradiation by gamma-rays of a 60Co source. Measurements of the specific surface conductivity ?s, surface dissipation factor tan?s, volume dissipation factor tan?v, and the maximum surface potential Umax after charging with positive or negative ions by dc corona discharge, were carried out at room temperature in air of 65% humidity. Umax was found to have a strong dependence on irradiation dose especially at doses ranging up to 1 Mrad. Also, ?s exhibits a substantial decrease of up to seven orders of magnitude at doses from 100 krad to 1 Mrad. These effects are supposedly linked with the radiationally stimulated destruction of carbon chains on the polymer composite surface. On the other hand, at doses higher than 1-2 Mrad there is an extraordinary high rise of the specific surface conductivity of the samples containing 5 vol% filler which reaches nine orders of magnitude and more. This is attributed to the formation of chains of carbon nanoclusters in the near-to-surface layer of the polymer composite. (author)

391

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

DEFF Research Database (Denmark)

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

Kafka, Jan Robert; Geschke, Oliver

2011-01-01

392

A first approach to foot motion monitoring using conductive polymer sensors  

Science.gov (United States)

A study was conducted of socks fitted with thin flexible conductive polymer sensors for the potential use as a smart sock for monitoring foot motion. The thin flexible sensors consisted of a conductive polymer applied on an elastic textile substrate that exhibited a resistance change when strained. Quasi-static response tests of the basic sensor over a static load range of a few Newtons were conducted and showed a time varying response as observed by previous investigators. Dynamic testing through an electrodynamic shaker shows good dynamic response at a low frequency range, less than 4Hz. Strips of 12 cm x 1 cm of the sensor on fabric showed a reproducible basal resistance on the order of 10KOhms. Other geometries of the continuous sensors and correlation of strain to resistance variation were studied. Similar tests were performed on different textile substrates which vary in composition and microstructure, i.e. woven, knitted, nylon%, polyester%, etc... These sensors were integrated into socks and preliminary results indicate that distinct responses to different foot motion patterns are detected in sensors placed at different joint locations on the foot. Further processing of strain results from smart socks should provide information about the kinematics and dynamics of the human foot.

Castano, L. M.; Winkelmann, A. E.; Flatau, A. B.

2009-03-01

393

Conductivity and adhesion enhancement in low-temperature processed indium tin oxide/polymer nanocomposites  

International Nuclear Information System (INIS)

We report on the conductivity and adhesion enhancement of indium tin oxide (In2O3:Sn; ITO) nanoparticle films by the application of polymers as matrix material. We fabricated ITO layers at a maximum process temperature of 130 oC by modifying and spin-coating nanoparticulate ITO dispersions. Dispersions containing the organic film-forming agent polyvinylpyrrolidone (PVP) and the organofunctional coupling agent 3-methacryloxypropyltrimethoxysilane (MPTS) have been developed to obtain transparent and conducting coatings on substrates which do not withstand high process temperatures like polymers or already processed glasses. The layers were cured by UV-irradiation as well as by low-temperature heat treatment (T = 130 oC) in air and under forming gas atmosphere (N2/H2). The influence of the additives on the electrical, optical, morphological and mechanical layer properties is reported. Compared to best pure ITO layers (3.1 ?-1 cm-1), the ITO-MPTS-PVP nanocomposite coatings exhibit a conductance of 9.8 ?-1 cm-1. Stable sheet resistances of 750 ?/? at a coexistent transmittance of 86% at 550 nm for a layer thickness of about 1.3 ?m were achieved. The conductance enhancement is a consequence of the consolidation of the ITO nanoparticle network due to the acting shrinkage forces caused either by drying in the case of PVP or UV-irradiation induced condensation an-irradiation induced condensation and polymerization reactions in the case of MPTS.

394

Long-term cycle stability at a high current for nanocrystalline LiFePO4 coated with a conductive polymer  

International Nuclear Information System (INIS)

Highly uniform hierarchical-microstructured LiFePO4 particles with dumbbell- and donut-shape and individual LiFePO4 nanocrystals were prepared by a hydrothermal method utilizing citric acid or a triblock copolymer (Pluronic P123) as a surfactant. The cathode composed of the individual nanocrystalline LiFePO4 particles exhibited higher specific capacity than the cathodes composed of the hierarchically assembled microparticles. Coating a conductive polymer, poly-3,4-ethylenedioxythiophene (PEDOT), on the surface of LiFePO4 particles improved the battery performances such as large specific capacities, high rate capability and an improved cycle stability. The nanocrystalline LiFePO4 particles coated with PEDOT (20 wt%) exhibited the highest discharge capacities of 175 and 136 mAh g?1 for the first battery cycle and 163 and 128 mAh g?1 after 500 battery cycles, with a degradation rate of 6–7%, at the rates of 1 and 10 C, respectively. (paper)

395

Injection molded chips with integrated conducting polymer electrodes for electroporation of cells  

International Nuclear Information System (INIS)

We present the design-concept for an all polymer injection molded single use microfluidic device. The fabricated devices comprise integrated conducting polymer electrodes and Luer fitting ports to allow for liquid and electrical access. A case study of low voltage electroporation of biological cells in suspension is presented. The working principle of the electroporation device is based on a focusing of the electric field by means of a constriction in the flow channel for the cells. We demonstrate the use of AC voltage for electroporation by applying a 1 kHz, ±50 V square pulse train to the electrodes and show delivery of polynucleotide fluorescent dye in 46% of human acute monocytic leukemia cells passing the constriction.

396

Injection molded chips with integrated conducting polymer electrodes for electroporation of cells  

DEFF Research Database (Denmark)

We present the design-concept for an all polymer injection molded single use microfluidic device. The fabricated devices comprise integrated conducting polymer electrodes and Luer fitting ports to allow for liquid and electrical access. A case study of low voltage electroporation of biological cells in suspension is presented. The working principle of the electroporation device is based on a focusing of the electric field by means of a constriction in the flow channel for the cells. We demonstrate the use of AC voltage for electroporation by applying a 1 kHz, +/- 50 V square pulse train to the electrodes and show delivery of polynucleotide fluorescent dye in 46% of human acute monocytic leukemia cells passing the constriction.

Andresen, Kristian; Hansen, Morten

2010-01-01

397

Injection molded chips with integrated conducting polymer electrodes for electroporation of cells  

Science.gov (United States)

We present the design-concept for an all polymer injection molded single use microfluidic device. The fabricated devices comprise integrated conducting polymer electrodes and Luer fitting ports to allow for liquid and electrical access. A case study of low voltage electroporation of biological cells in suspension is presented. The working principle of the electroporation device is based on a focusing of the electric field by means of a constriction in the flow channel for the cells. We demonstrate the use of AC voltage for electroporation by applying a 1 kHz, ±50 V square pulse train to the electrodes and show delivery of polynucleotide fluorescent dye in 46% of human acute monocytic leukemia cells passing the constriction.

Ødegaard Andresen, Kristian; Hansen, Morten; Matschuk, Maria; Terpager Jepsen, Søren; Schiøtt Sørensen, Henrik; Utko, Pawel; Selmeczi, Dávid; Hansen, Thomas S.; Larsen, Niels B.; Rozlosnik, Noemi; Taboryski, Rafael

2010-05-01

398

Electromagnetic interference shielding effectiveness of nanoreinforced polymer composites deposited with conductive metallic thin films  

Energy Technology Data Exchange (ETDEWEB)

The effect of using conductive metallic thin films deposited on high density polyethylene (HDPE) and styrene butadiene copolymer (SBC) in conjunction with carbon nanofiber (CNF) reinforcement of HDPE and SBC was investigated in order to improve the electromagnetic interference shielding effectiveness (EMI SE) of the structures. Thin films of copper, silver and aluminum were deposited by thermal evaporation onto the polymeric matrices and its composites (0-20 wt.% of CNFs). Results show a synergistic effect of the two approaches (metallic coating and CNF reinforcement) toward improving the EMI SE. The chemical composition, surface morphology, carbon nanofiber distribution, thickness and microstructure of metallic coated polymers are examined using X-Ray Diffraction and Scanning Electron Microscopy. - Highlights: Black-Right-Pointing-Pointer Metallic thin films were evaporated on carbon nanofiber reinforced polymers. Black-Right-Pointing-Pointer The electromagnetic shielding effectiveness of the structures was evaluated. Black-Right-Pointing-Pointer Thin films and carbon nanofibers synergistically improved the shielding effectiveness.

Mihut, D.M., E-mail: dorinamm@yahoo.com [Department of Mechanical Engineering, The University of Texas Pan American, 1201 W University Drive, Edinburg, TX (United States); Lozano, K. [Department of Mechanical Engineering, The University of Texas Pan American, 1201 W University Drive, Edinburg, TX (United States); Tidrow, S.C. [Department of Physics and Geology, The University of Texas Pan American, 1201 W University Drive, Edinburg, TX (United States); Garcia, H. [Department of Mechanical Engineering, The University of Texas Pan American, 1201 W University Drive, Edinburg, TX (United States)

2012-08-31

399

NMR and conductivity study of PEO-based composite polymer electrolytes  

International Nuclear Information System (INIS)

The influence of the space charge created by the presence of TiO2 nanoparticles on the lithium and polymer chain mobility have been investigated in solid composite polymer electrolytes (CPE), poly(ethylene oxide) (PEO) LiClO4, by using complex impedance spectroscopy and nuclear magnetic resonance (NMR). Special care was taken with the synthesis and the characterization of the TiO2 particles and with the composite preparation. The conductivity and NMR measurements were undertaken in composite samples nanoparticles having constant total surface area. Proton (1H) and lithium (7Li) lineshapes and spin-lattice relaxation times were measured as a function of temperature. Activation energies extracted from the 7Li relaxation data are in the range 0.20-0.22 eV. The NMR decoupling experiment suggests that the Li-Li interactions are stronger in the composites when compared with those of the ceramic free electrolytes

400

Computational design of mixers and pumps for microfluidic systems, based on electrochemically-active conducting polymers.  

Science.gov (United States)

We present a theoretical description of the propagation of composition waves along a strip of electrochemically-active conducting polymer, upon electrochemical stimulation. We develop an efficient solution of the electro-neutral Nernst-Plank equations in 2-D for electromigration and diffusional transport in the solution based on an extension of the methods of Scharfetter and Gummel [D. L. Scharfetter and H. K. Gummel, IEEE Trans. Electron Devices, 1969, ED16, 64-77.] and of Cohen and Cooley [H. Cohen and J. W. Cooley, Biophys. J., 1965, 5, 145-162.], and demonstrate important effects of the geometry of the cell. Under some circumstances, waves reflecting back from the end of the strip are predicted. We then demonstrate theoretically how such waves, associated as they are with expansion of the polymer, could be employed to enhance mixing or induce pumping in microfluidic systems. PMID:21350739

Kannappan, Karthik; Bogle, Gib; Travas-Sejdic, Jadranka; Williams, David E

2011-03-28

401

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

Energy Technology Data Exchange (ETDEWEB)

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

Vardeny, Z.V.

1991-10-08

402

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

Energy Technology Data Exchange (ETDEWEB)

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

Vardeny, Z.V.

1991-10-08

403

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

Science.gov (United States)

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

Raveh, Moran; Liu, Liang; Mandler, Daniel

2013-07-14

404

Effects of 160 MeV Ni12+ ion irradiation on polypyrrole conducting polymer electrode materials for all polymer redox supercapacitor  

International Nuclear Information System (INIS)

Electronically conducting polymers are suitable electrode materials for high performance supercapacitors, for their high specific capacitance and high dc conductivity in the charged state. Supercapacitors and batteries are energy storage and conversion systems which satisfies the requirements of high specific power and energy in a complementary way. Ion beam {energy > 1 MeV} irradiation on the polymer is a novel technique to enhance or alter the properties like conductivity, density, chain length and solubility. Conducting polymer polypyrrole thin films doped with LiClO4 are synthesized electrochemically on ITO coated glass substrate and are irradiated with 160 MeV Ni12+ ions at different fluence 5 x 101, 5 x 1011 and 3 x 1012 ions cm-2. Dc conductivity measurement of the irradiated films showed 50-60% increase in conductivity which is may be due to increase of carrier concentration in the polymer film as observed in UV-Vis spectroscopy and other effects like cross-linking of polymer chain, bond breaking and creation of defects sites. X-ray diffractogram study shows that the degree of crystallinity of polypyrrole increases in SHI irradiation and is proportionate to ion fluence. The capacitance of the irradiated films is lowered but the capacitance of the supercapacitors with irradiated films showed enhanced stability compared to the devices with unirradiated films while characterized for cycle life up tms while characterized for cycle life up to 10,000 cycles

405

Mesoscale Origin of the Enhanced Cycling-Stability of the Si-Conductive Polymer Anode for Li-ion Batteries  

Energy Technology Data Exchange (ETDEWEB)

Electrode used in lithium-ion battery is invariably a composite of multifunctional components. The performance of the electrode is controlled by the interactive function of all components at mesoscale. Fundamental understanding of mesoscale phenomenon sets the basis for innovative designing of new materials. Here we report the achievement and origin of a significant performance enhancement of electrode for lithium ion batteries based on Si nanoparticles wrapped with conductive polymer. This new material is in marked contrast with conventional material, which exhibit fast capacity fade. In-situ TEM unveils that the enhanced cycling stability of the conductive polymer-Si composite is associated with mesoscale concordant function of Si nanoparticles and the conductive polymer. Reversible accommodation of the volume changes of Si by the conductive polymer allows good electrical contact between all the particles during the cycling process. In contrast, the failure of the conventional Si-electrode is probed to be the inadequate electrical contact.

Gu, Meng; Xiao, Xingcheng; Liu, Gao; Thevuthasan, Suntharampillai; Baer, Donald R.; Zhang, Jiguang; Liu, Jun; Browning, Nigel D.; Wang, Chong M.

2014-01-14

406

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

Science.gov (United States)

Ionic mobility of electrolyte materials is essentially determined by the nanoscale interactions, the ion-ion interactions and ion-solvent interactions. We quantitatively evaluated the interactive situation of the lithium polymer gel electrolytes through the measurements of ionic conductivity and diffusion coefficients of the mobile species of the lithium polymer electrolytes. The interactive force between the cation and anion in the gel depended on the mixing ratio of the binary solvent, ethylene carbonate plus dimethyl carbonate (EC/DMC). The gel with the solvent (3:7 EC:DMC) showed minimal cation-anion interaction, which is the cause of the highest ionic mobility compared with those of the other gels with different solvents. This suggests that the cation-anion interaction does not simply depend on the dielectric constant of the solvent but is associated with the solvation condition of the lithium. In the case of the gel with the 3:7 EC/DMC solvent, most of the EC species strongly coordinate to a lithium ion, forming the stable solvated lithium, Li(EC)(3)(+), and there are no residual EC species for exchange with them. As a result, the solvating EC species would be a barrier that restricts the anion attack to the lithium leading to the smallest cation-anion interaction. On the other hand, interaction between the cation and polar sites, hydroxyl and oxygen groups of ether of the polyvinyl butyral (PVB) and polyethylene oxide (PEO) polymer, respectively, in the gels was another dominant factor responsible for cation mobility. It increased with increasing polar site concentration per lithium. In case of the PVB gels, cation-anion interaction increased with an increasing polymer fraction of the gel contrary to the independent feature of PEO gels with the change of the polymer fraction. This indicates that the cation-anion interaction is associated with the polymer structure of the gel characterized by the kind and configuration of polar groups, molecular weight, and network morphology of the polymer. PMID:22831401

Saito, Yuria; Okano, Miki; Kubota, Keigo; Sakai, Tetsuo; Fujioka, Junji; Kawakami, Tomohiro

2012-08-23

407

Computational screening of structural and compositional factors for electrically conductive coordination polymers.  

Science.gov (United States)

The combination of organic and inorganic chemical building blocks to form metal-organic frameworks (MOFs) offers opportunities for producing functional materials suitable for energy generation, storage and conversion. However, such applications rely on robust electron transport and the design of conductive hybrid materials is still in its infancy. Here we apply density functional theory to assess the important structural and compositional factors for forming conducting MOFs. We focus on 1D metal-organic polymers as a model system and assess the choice of organic, inorganic and linking units. The results demonstrate that electronic communication is sensitive to the energy and symmetry of the frontier orbitals associated with the organic and inorganic building blocks and offers guidance on how to optimise electrical conduction in hybrid materials. PMID:24569694

Tiana, Davide; Hendon, Christopher H; Walsh, Aron; Vaid, Thomas P

2014-07-28

408

Tunneling Microscopy and Spectroscopy of Semiconductor Nanocrystals  

Science.gov (United States)

Semiconductor nanocrystals of different compounds have been imaged and partially characterized by tunneling based techniques. Our nanocrystals include CdSe, Au and CdS coated with organic molecules. Our initial studies show immobile and isolated single Au, CdSe, and CdS nanocrystals images. Crystals were attached chemically to a conducting substrates using different combinations of ligands and SAM bi