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Sample records for highly luminescent polymer

  1. Luminescent lanthanide coordination polymers

    SciTech Connect

    Ma, L.; Evans, O.R.; Foxman, B.M.; Lin, W.

    1999-12-13

    One-dimensional lanthanide coordination polymers with the formula Ln(isonicotinate){sub 3}(H{sub 2}O){sub 2} (Ln = Ce, Pr, Nd, Sm, Eu, Tb; 1a-f) were synthesized by treating nitrate or perchlorate salts of Ln(III) with 4-pyridinecarboxaldehyde under hydro(solvo)thermal conditions. Single-crystal and powder X-ray diffraction studies indicate that these lanthanide coordination polymers adopt two different structures. While Ce(III), Pr(III), and Nd(III) complexes adopt a chain structure with alternating Ln-(carboxylate){sub 2}-Ln and Ln-(carboxylate){sub 4}-Ln linkages, Sm(III), Eu(III), and Tb(III) complexes have a doubly carboxylate-bridged infinite-chain structure with one chelating carboxylate group on each metal center. In both structures, the lanthanide centers also bind to two water molecules to yield an eight-coordinate, square antiprismatic geometry. The pyridine nitrogen atoms of the isonicotinate groups do not coordinate to the metal centers in these lanthanide(III) complexes; instead, they direct the formation of Ln(III) coordination polymers via hydrogen bonding with coordinated water molecules. Photoluminescence measurements show that Tb(isonicotinate){sub 3}(H{sub 2}O){sub 2} is highly emissive at room temperature with a quantum yield of {approximately}90%. These results indicate that highly luminescent lanthanide coordination polymers can be assembled using a combination of coordination and hydrogen bonds. Crystal data for 1a: monoclinic space group P2{sub 1}/c, a = 9.712(2) {angstrom}, b = 19.833(4) {angstrom}, c = 11.616(2) {angstrom}, {beta} = 111.89(3){degree}, Z = 4. Crystal data for 1f: monoclinic space group C2/c, a = 20.253(4) {angstrom}, b = 11.584(2) {angstrom}, c = 9.839(2) {angstrom}, {beta} = 115.64(3){degree}, Z = 8.

  2. Highly sensitive gas-phase explosive detection by luminescent microporous polymer networks.

    PubMed

    Räupke, André; Palma-Cando, Alex; Shkura, Eugen; Teckhausen, Peter; Polywka, Andreas; Görrn, Patrick; Scherf, Ullrich; Riedl, Thomas

    2016-01-01

    We propose microporous networks (MPNs) of a light emitting spiro-carbazole based polymer (PSpCz) as luminescent sensor for nitro-aromatic compounds. The MPNs used in this study can be easily synthesized on arbitrarily sized/shaped substrates by simple and low-cost electrochemical deposition. The resulting MPN afford an extremely high specific surface area of 1300 m(2)/g, more than three orders of magnitude higher than that of the thin films of the respective monomer. We demonstrate, that the luminescence of PSpCz is selectively quenched by nitro-aromatic analytes, e.g. nitrobenzene, 2,4-DNT and TNT. In striking contrast to a control sample based on non-porous spiro-carbazole, which does not show any luminescence quenching upon exposure to TNT at levels of 3 ppm and below, the microporous PSpCz shows a clearly detectable response even at TNT concentrations as low as 5 ppb, clearly demonstrating the advantage of microporous films as luminescent sensors for traces of explosive analytes. This level states the vapor pressure of TNT at room temperature. PMID:27373905

  3. Highly sensitive gas-phase explosive detection by luminescent microporous polymer networks

    NASA Astrophysics Data System (ADS)

    Räupke, André; Palma-Cando, Alex; Shkura, Eugen; Teckhausen, Peter; Polywka, Andreas; Görrn, Patrick; Scherf, Ullrich; Riedl, Thomas

    2016-07-01

    We propose microporous networks (MPNs) of a light emitting spiro-carbazole based polymer (PSpCz) as luminescent sensor for nitro-aromatic compounds. The MPNs used in this study can be easily synthesized on arbitrarily sized/shaped substrates by simple and low-cost electrochemical deposition. The resulting MPN afford an extremely high specific surface area of 1300 m2/g, more than three orders of magnitude higher than that of the thin films of the respective monomer. We demonstrate, that the luminescence of PSpCz is selectively quenched by nitro-aromatic analytes, e.g. nitrobenzene, 2,4-DNT and TNT. In striking contrast to a control sample based on non-porous spiro-carbazole, which does not show any luminescence quenching upon exposure to TNT at levels of 3 ppm and below, the microporous PSpCz shows a clearly detectable response even at TNT concentrations as low as 5 ppb, clearly demonstrating the advantage of microporous films as luminescent sensors for traces of explosive analytes. This level states the vapor pressure of TNT at room temperature.

  4. Highly sensitive gas-phase explosive detection by luminescent microporous polymer networks

    PubMed Central

    Räupke, André; Palma-Cando, Alex; Shkura, Eugen; Teckhausen, Peter; Polywka, Andreas; Görrn, Patrick; Scherf, Ullrich; Riedl, Thomas

    2016-01-01

    We propose microporous networks (MPNs) of a light emitting spiro-carbazole based polymer (PSpCz) as luminescent sensor for nitro-aromatic compounds. The MPNs used in this study can be easily synthesized on arbitrarily sized/shaped substrates by simple and low-cost electrochemical deposition. The resulting MPN afford an extremely high specific surface area of 1300 m2/g, more than three orders of magnitude higher than that of the thin films of the respective monomer. We demonstrate, that the luminescence of PSpCz is selectively quenched by nitro-aromatic analytes, e.g. nitrobenzene, 2,4-DNT and TNT. In striking contrast to a control sample based on non-porous spiro-carbazole, which does not show any luminescence quenching upon exposure to TNT at levels of 3 ppm and below, the microporous PSpCz shows a clearly detectable response even at TNT concentrations as low as 5 ppb, clearly demonstrating the advantage of microporous films as luminescent sensors for traces of explosive analytes. This level states the vapor pressure of TNT at room temperature. PMID:27373905

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

    NASA Astrophysics Data System (ADS)

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

    2012-02-01

    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.

  6. Highly effective heterogeneous chemosensors of luminescent silica@coordination polymer core-shell micro-structures for metal ion sensing

    NASA Astrophysics Data System (ADS)

    Cho, Won; Lee, Hee Jung; Choi, Sora; Kim, Yoona; Oh, Moonhyun

    2014-10-01

    Heterogeneous solid sensors are regarded as promising next-generation sensor due to their excellent chemical stability, low contamination, and excellent recyclability, despite their low sensitivity and weak signal. The dispersity and signals specifically from the exterior of solid sensors are critical aspects which define the sensing sensitivity and selectivity. A novel strategy for the preparation of ideal heterogeneous sensors based upon luminescent lanthanide coordination polymers (LnCP) has been demonstrated. Ideal heterogeneous sensors are systematically achieved by producing the sensors in small, uniform, and thin core-shell particles (silica@LnCP, Ln = Eu, Tb). Eventually, we found that the extremely small amount of well-structured silica@LnCP microsphere, less than ca. 1/400 compared to the amount of several known coordination polymer-based sensors, was sufficient to achieve a reliable Cu2+ sensing with even much greater sensitivity (ca. 550% improvement).

  7. Luminescent Metal-Containing Polymers for White Light Emission.

    PubMed

    Ho, Cheuk-Lam; Wong, Wai-Yeung

    2016-10-01

    This chapter focuses on the recent developments in luminescent metallopolymers. Synthetic routes to these polymers are briefly described and their applications in polymer white light-emitting diodes are discussed. PMID:27573506

  8. ION AND MOLECULE SENSORS USING MOLECULAR RECOGNITION IN LUMINESCENT, CONDUCTIVE POLYMERS

    EPA Science Inventory

    This program integrates three individual, highly interactive projects that will use molecular recognition strategies to develop sensor technology based on luminescent, conductive polymers that contain sites for binding specific molecules or ions in the presence of related molecul...

  9. Three luminescent d10 metal coordination polymers assembled from a semirigid V-shaped ligand with high selective detecting of Cu2+ ion and nitrobenzene

    NASA Astrophysics Data System (ADS)

    Wu, Wei-Ping; Liu, Ping; Liang, Yu-Tong; Cui, Lin; Xi, Zheng-Ping; Wang, Yao-Yu

    2015-08-01

    Three 2D luminescent coordination polymers with helical frameworks, [ZnL2]n (1) and {[ML2]·(H2O)}n (M=Zn (2), Cd (3)) (HL=4-((2-methyl-1 H-imidazol-1-yl)methyl)benzoic acid), have been assembled under hydro(solvo)thermal conditions. Complex 1 is in chiral space group and displays a rare 2D→2D 2-fold parallel interpenetrated layer network with two types of chiral double helixes. Interestingly, the single crystal structure analyses indicate the coexistence of enantiomers la and 1b in one pot, while the bulk crystallization of 1 are racemic mixtures based on the CD measurement. 2 and 3 are isostructural, in the structure, there are two kinds of 2D chiral helical-layers which stack in an -ABAB- sequence leading to the overall structure are mesomer and achiral. All compounds display intense luminescence in solid state at room temperature with high chemical and thermal stability. More importantly, 1 has been successfully applied in the detection of Cu2+ ions in aqueous media and nitrobenzene and the probable detecting mechanism was also discussed.

  10. Highly Luminescent Microporous Organic Polymer with Lewis Acidic Boron Sites on the Pore Surface: Ratiometric Sensing and Capture of F(-) Ions.

    PubMed

    Suresh, Venkata M; Bandyopadhyay, Arkamita; Roy, Syamantak; Pati, Swapan K; Maji, Tapas Kumar

    2015-07-20

    Reversible and selective capture/detection of F(-) ions in water is of the utmost importance, as excess intake leads to adverse effects on human health. Highly robust Lewis acidic luminescent porous organic materials have potential for efficient sequestration and detection of F(-) ions. Herein, the rational design and synthesis of a boron-based, Lewis acidic microporous organic polymer (BMOP) derived from tris(4-bromo-2,3,5,6-tetramethylphenyl)boron nodes and diethynylbiphenyl linkers with a pore size of 1.08 nm for selective turn-on sensing and capture of F(-) ion are reported. The presence of a vacant pπ orbital on the boron center of BMOP results in intramolecular charge transfer (ICT) from the linker to boron. BMOP shows selective turn-on blue emission for F(-) ions in aqueous mixtures with a detection limit of 2.6 μM. Strong B-F interactions facilitate rapid sequestration of F(-) by BMOP. The ICT emission of BMOP can be reversibly regenerated by addition of an excess of water, and the polymer can be reused several times. PMID:26074403

  11. Nanoscale coordination polymers exhibiting luminescence properties and NMR relaxivity

    NASA Astrophysics Data System (ADS)

    Chelebaeva, Elena; Larionova, Joulia; Guari, Yannick; Ferreira, Rute A. S.; Carlos, Luis D.; Trifonov, Alexander A.; Kalaivani, Thangavel; Lascialfari, Alessandro; Guérin, Christian; Molvinger, Karine; Datas, Lucien; Maynadier, Marie; Gary-Bobo, Magali; Garcia, Marcel

    2011-03-01

    This article presents the first example of ultra-small (3-4 nm) magneto-luminescent cyano-bridged coordination polymer nanoparticles Ln0.333+Gdx3+/[Mo(CN)8]3- (Ln = Eu (x = 0.34), Tb (x = 0.35)) enwrapped by a natural biocompatible polymer chitosan. The aqueous colloidal solutions of these nanoparticles present a luminescence characteristic of the corresponding lanthanides (5D0 --> 7F0-4 (Eu3+) or the 5D4 --> 7F6-2 (Tb3+)) under UV excitation and a green luminescence of the chitosan shell under excitation in the visible region. Magnetic Resonance Imaging (MRI) efficiency, i.e. the nuclear relaxivity, measurements performed for Ln0.333+Gdx3+/[Mo(CN)8]3- nanoparticles show r1p and r2p relaxivities slightly higher than or comparable to the ones of the commercial paramagnetic compounds Gd-DTPA® or Omniscan® indicating that our samples may potentially be considered as a positive contrast agent for MRI. The in vitro studies performed on these nanoparticles show that they maybe internalized into human cancer and normal cells and well detected by fluorescence at the single cell level. They present high stability even at low pH and lack of cytotoxicity both in human cancer and normal cells.This article presents the first example of ultra-small (3-4 nm) magneto-luminescent cyano-bridged coordination polymer nanoparticles Ln0.333+Gdx3+/[Mo(CN)8]3- (Ln = Eu (x = 0.34), Tb (x = 0.35)) enwrapped by a natural biocompatible polymer chitosan. The aqueous colloidal solutions of these nanoparticles present a luminescence characteristic of the corresponding lanthanides (5D0 --> 7F0-4 (Eu3+) or the 5D4 --> 7F6-2 (Tb3+)) under UV excitation and a green luminescence of the chitosan shell under excitation in the visible region. Magnetic Resonance Imaging (MRI) efficiency, i.e. the nuclear relaxivity, measurements performed for Ln0.333+Gdx3+/[Mo(CN)8]3- nanoparticles show r1p and r2p relaxivities slightly higher than or comparable to the ones of the commercial paramagnetic compounds Gd

  12. Three luminescent d{sup 10} metal coordination polymers assembled from a semirigid V-shaped ligand with high selective detecting of Cu{sup 2+} ion and nitrobenzene

    SciTech Connect

    Wu, Wei-Ping; Liu, Ping; Liang, Yu-Tong; Cui, Lin; Xi, Zheng-Ping; Wang, Yao-Yu

    2015-08-15

    Three 2D luminescent coordination polymers with helical frameworks, [ZnL{sub 2}]{sub n} (1) and ([ML{sub 2}]·(H{sub 2}O)){sub n} (M=Zn (2), Cd (3)) (HL=4-((2-methyl-1 H-imidazol-1-yl)methyl)benzoic acid), have been assembled under hydro(solvo)thermal conditions. Complex 1 is in chiral space group and displays a rare 2D→2D 2-fold parallel interpenetrated layer network with two types of chiral double helixes. Interestingly, the single crystal structure analyses indicate the coexistence of enantiomers la and 1b in one pot, while the bulk crystallization of 1 are racemic mixtures based on the CD measurement. 2 and 3 are isostructural, in the structure, there are two kinds of 2D chiral helical-layers which stack in an -ABAB- sequence leading to the overall structure are mesomer and achiral. All compounds display intense luminescence in solid state at room temperature with high chemical and thermal stability. More importantly, 1 has been successfully applied in the detection of Cu{sup 2+} ions in aqueous media and nitrobenzene and the probable detecting mechanism was also discussed. - Graphical abstract: Three luminescent d{sup 10} metal coordination polymers with helical-layer based on 4-((2-methyl-1H-imidazol-1-yl)methyl)benzoic acid have been obtained. Compound 1 shows high selective detecting for Cu{sup 2+} ion in aqueous and nitrobenzene. - Highlights: • Three coordination polymers with chiral helical-layer have been obtained. • 1 Can luminescent detect Cu{sup 2+} ion in aqueous media and nitrobenzene. • Racemic mixture or mesomer compounds can be obtained by controlling the reaction conditions.

  13. Bismuth-Based Coordination Polymers with Efficient Aggregation-Induced Phosphorescence and Reversible Mechanochromic Luminescence.

    PubMed

    Toma, Oksana; Allain, Magali; Meinardi, Francesco; Forni, Alessandra; Botta, Chiara; Mercier, Nicolas

    2016-07-01

    Two bismuth coordination polymers (CPs), (TBA)[BiBr4 (bp4mo)] (TBA=tetrabutylammonium) and [BiBr3 (bp4mo)2 ], which are based on the rarely used simple ditopic ligand N-oxide-4,4'-bipyridine (bp4mo), show mechanochromic luminescence (MCL). High solid-state phosphorescence quantum yields of up to 85 % were determined for (TBA)[BiBr4 (bp4mo)] (λem =540 nm). Thorough investigations of the luminescence properties combined with DFT and TDDFT calculations revealed that the emission is due to aggregation-induced phosphorescence (AIP). Upon grinding, both samples became amorphous, and their luminescence changed from yellow to orange and red, respectively. Heating or exposure to water vapor led to the recovery of the initial luminescence. These materials are the first examples of mechanochromic phosphors based on bismuth(III). PMID:27166740

  14. Lanthanide coordination polymers: Synthesis, diverse structure and luminescence properties

    SciTech Connect

    Song, Xue-Qin Lei, Yao-Kun; Wang, Xiao-Run; Zhao, Meng-Meng; Peng, Yun-Qiao; Cheng, Guo-Quan

    2014-10-15

    The new semirigid exo-bidentate ligand incorporating furfurysalicylamide terminal groups, namely, 1,4-bis([(2′-furfurylaminoformyl)phenoxyl]methyl)-2,5-bismethylbenzene (L) was synthesized and used as building blocks for constructing lanthanide coordination polymers with luminescent properties. The series of lanthanide nitrate complexes have been characterized by elemental analysis, IR spectroscopy, and X-ray diffraction analysis. The semirigid ligand L, as a bridging ligand, reacts with lanthanide nitrates forming three distinct structure types: chiral noninterpenetrated two-dimensional (2D) honeycomblike (6,3) (hcb, Schläfli symbol 6{sup 3}, vertex symbol 6 6 6) topological network as type I, 1D zigzag chain as type II and 1D trapezoid ladder-like chain as type III. The structural diversities indicate that lanthanide contraction effect played significant roles in the structural self-assembled process. The luminescent properties of Eu{sup III}, Tb{sup III} and Dy{sup III} complexes are discussed in detail. Due to the good match between the lowest triplet state of the ligand and the resonant energy level of the lanthanide ion, the lanthanide ions in Eu{sup III}, Tb{sup III} and Dy{sup III} complexes can be efficiently sensitized by the ligand. - Graphical abstract: We present herein six lanthanide coordination polymers of a new semirigid exo-bidentate ligand which not only display diverse structures but also possess strong luminescence properties. - Highlights: • We present lanthanide coordination polymers of a new semirigid exo-bidentate ligand. • The lanthanide coordination polymers exhibit diverse structures. • The luminescent properties of Tb{sup III}, Eu{sup III} and Dy{sup III} complexes are discussed in detail.

  15. Supramolecular Luminescence from Oligofluorenol-Based Supramolecular Polymer Semiconductors

    PubMed Central

    Zhang, Guang-Wei; Wang, Long; Xie, Ling-Hai; Lin, Jin-Yi; Huang, Wei

    2013-01-01

    Supramolecular luminescence stems from non-covalent exciton behaviors of active π-segments in supramolecular entities or aggregates via intermolecular forces. Herein, a π-conjugated oligofluorenol, containing self-complementary double hydrogen bonds, was synthesized using Suzuki coupling as a supramolecular semiconductor. Terfluorenol-based random supramolecular polymers were confirmed via concentration-dependent nuclear magnetic resonance (NMR) and dynamic light scattering (DLS). The photoluminescent spectra of the TFOH-1 solution exhibit a green emission band (g-band) at approximately ~520 nm with reversible features, as confirmed through titration experiments. Supramolecular luminescence of TFOH-1 thin films serves as robust evidence for the aggregates of g-band. Our results suggest that the presence of polyfluorene ketone defects is a sufficient condition, rather than a sufficient-necessary condition for the g-band. Supramolecular electroluminescence will push organic devices into the fields of supramolecular optoelectronics, spintronics, and mechatronics. PMID:24232455

  16. Luminescent lanthanide coordination polymers synthesized via in-situ hydrolysis of dimethyl-3,4-furandicarboxylate

    SciTech Connect

    Greig, Natalie E.; Einkauf, Jeffrey D.; Clark, Jessica M.; Corcoran, Eric J.; Karram, Joseph P.; Kent, Charles A.; Eugene, Vadine E.; Chan, Benny C.; Lill, Daniel T. de

    2015-05-15

    Dimethyl-3,4-furandicarboxylate undergoes hydrolysis under hydrothermal conditions with lanthanide (Ln) ions to form two-dimensional coordination polymers, [Ln(C{sub 6}H{sub 2}O{sub 5})(C{sub 6}H{sub 3}O{sub 5})(H{sub 2}O)]{sub n} (Ln=Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu). The resulting materials exhibit luminescent properties with quantum yields and lifetimes for the Eu(III) and Tb(III) compounds of 1.1±0.3% and 0.387±0.0001 ms, and 3.3±0.8% and 0.769±0.006 ms, respectively. Energy values for the singlet and triplet states were determined for dimethyl-3,4-furandicarboxylate and 3,4-furandicarboxylic acid. Excited state dynamics and structural features are examined to explicate the reported quantum yields. A series of other FDC structures is briefly presented. - Graphical abstract: A new two-dimensional coordination polymer derived from the in-situ hydrolysis of a furan dimethyl ester with lanthanide(III) ions was obtained in order to study its photophysical behavior when constructed from trivalent Eu and Tb. Quantum yields, lifetime measurements, and singlet/triplet state energies values were obtained. The nature of the material's excited state dynamics is examined and correlated to its structure in order to explain the overall luminescent efficiency of the system. - Highlights: • A new lanthanide–furandicarboxylate coordination polymer is presented. • Eu and Tb compounds display luminescent properties, albeit with low quantum yields. • Photophysical behavior explained through the compound's triplet state and structure. • Nonradiative deactivation of luminescence through high-energy oscillators was noted. • Molecular modeling of the organic moiety was conducted.

  17. Lanthanide coordination polymers: Synthesis, diverse structure and luminescence properties

    NASA Astrophysics Data System (ADS)

    Song, Xue-Qin; Lei, Yao-Kun; Wang, Xiao-Run; Zhao, Meng-Meng; Peng, Yun-Qiao; Cheng, Guo-Quan

    2014-10-01

    The new semirigid exo-bidentate ligand incorporating furfurysalicylamide terminal groups, namely, 1,4-bis{[(2‧-furfurylaminoformyl)phenoxyl]methyl}-2,5-bismethylbenzene (L) was synthesized and used as building blocks for constructing lanthanide coordination polymers with luminescent properties. The series of lanthanide nitrate complexes have been characterized by elemental analysis, IR spectroscopy, and X-ray diffraction analysis. The semirigid ligand L, as a bridging ligand, reacts with lanthanide nitrates forming three distinct structure types: chiral noninterpenetrated two-dimensional (2D) honeycomblike (6,3) (hcb, Schläfli symbol 63, vertex symbol 6 6 6) topological network as type I, 1D zigzag chain as type II and 1D trapezoid ladder-like chain as type III. The structural diversities indicate that lanthanide contraction effect played significant roles in the structural self-assembled process. The luminescent properties of EuIII, TbIII and DyIII complexes are discussed in detail. Due to the good match between the lowest triplet state of the ligand and the resonant energy level of the lanthanide ion, the lanthanide ions in EuIII, TbIII and DyIII complexes can be efficiently sensitized by the ligand.

  18. Fabrication of Superhydrophobic and Luminescent Rare Earth/Polymer complex Films.

    PubMed

    Wang, Zefeng; Ye, Weiwei; Luo, Xinran; Wang, Zhonggang

    2016-01-01

    The motivation of this work is to create luminescent rare earth/polymer films with outstanding water-resistance and superhydrophobicity. Specifically, the emulsion polymerization of styrene leads to core particles. Then core-shell-structured polymer nanoparticles are synthesized by copolymerization of styrene and acrylic acid on the core surface. The coordination reaction between carboxylic groups and rare earth ions (Eu(3+) and Tb(3+)) generates uniform spherical rare earth/polymer nanoparticles, which are subsequently complexed with PTFE microparticles to obtain micro-/nano-scaled PTFE/rare earth films with hierarchical rough morphology. The films exhibit large water contact angle up to 161° and sliding angle of about 6°, and can emit strong red and green fluorescence under UV excitation. More surprisingly, it is found that the films maintain high fluorescence intensity after submersed in water and even in aqueous salt solution for two days because of the excellent water repellent ability of surfaces. PMID:27086735

  19. High performance polymer development

    NASA Technical Reports Server (NTRS)

    Hergenrother, Paul M.

    1991-01-01

    The term high performance as applied to polymers is generally associated with polymers that operate at high temperatures. High performance is used to describe polymers that perform at temperatures of 177 C or higher. In addition to temperature, other factors obviously influence the performance of polymers such as thermal cycling, stress level, and environmental effects. Some recent developments at NASA Langley in polyimides, poly(arylene ethers), and acetylenic terminated materials are discussed. The high performance/high temperature polymers discussed are representative of the type of work underway at NASA Langley Research Center. Further improvement in these materials as well as the development of new polymers will provide technology to help meet NASA future needs in high performance/high temperature applications. In addition, because of the combination of properties offered by many of these polymers, they should find use in many other applications.

  20. Semiconducting Polymer Nanoparticles with Persistent Near-Infrared Luminescence for In Vivo Optical Imaging.

    PubMed

    Palner, Mikael; Pu, Kanyi; Shao, Shirley; Rao, Jianghong

    2015-09-21

    Materials with persistent luminescence are attractive for in vivo optical imaging since they have a long lifetime that allows the separation of excitation of fluorophores and image acquisition for time-delay imaging, thus eliminating tissue autofluorescence associated with fluorescence imaging. Persistently luminescent nanoparticles have previously been fabricated from toxic rare-earth metals. This work reports that nanoparticles made of the conjugated polymer MEH-PPV can generate luminescence persisting for an hour upon single excitation. A near-infrared dye was encapsulated in the conjugated polymer nanoparticle to successfully generate persistent near-infrared luminescence through resonance energy transfer. This new persistent luminescence nanoparticles have been demonstrated for optical imaging applications in living mice. PMID:26223794

  1. High Performance Polymers

    NASA Technical Reports Server (NTRS)

    Venumbaka, Sreenivasulu R.; Cassidy, Patrick E.

    2003-01-01

    This report summarizes results from research on high performance polymers. The research areas proposed in this report include: 1) Effort to improve the synthesis and to understand and replicate the dielectric behavior of 6HC17-PEK; 2) Continue preparation and evaluation of flexible, low dielectric silicon- and fluorine- containing polymers with improved toughness; and 3) Synthesis and characterization of high performance polymers containing the spirodilactam moiety.

  2. Observation of polymer degradation processes in photovoltaic modules via luminescence detection

    NASA Astrophysics Data System (ADS)

    Röder, B.; Ermilov, E. A.; Philipp, D.; Köhl, M.

    2008-08-01

    The estimation of PV-modules lifetime facilitates the further development and helps to lower risks for producers and investors. One base for this extensive testing work is the knowledge of the degradation kinetics of encapsulating polymer materials. Besides ethylen-vinylacetate copolymer (EVA), which is the prevalent material for encapsulation, new materials like Poly-Vinyl-Butyral (PVB), and thermoplastic Poly-Urethan (TPU) become available and need the assessment of their properties and the durability impact. In this context is it very important to identify the extent of degradation caused by different parameters in order to identify the determining factor of polymer degradation as well as potential interactions between different degradation processes. To simulate long time degeneration processes accelerated aging under damp-heat and high-UV conditions was performed on different EVA, TPU, and PVB samples. In this paper we report first results on measuring fluorescence spectra from different encapsulation materials after accelerated ageing in dependence on time and aging procedure. Our investigations clearly demonstrate that it is possible to follow damp-heat and UV induced aging processes of different polymers used in PV-modules as encapsulation materials by luminescence detection.

  3. Photoelectron spectroscopic investigation of in-vacuum-prepared luminescent polymer thin films directly from solution

    NASA Astrophysics Data System (ADS)

    Dam, N.; Beerbom, M. M.; Braunagel, J. C.; Schlaf, R.

    2005-01-01

    Thin films of the luminescent polymer poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) were deposited in high vacuum directly from toluene solution on Ag substrates using a homemade electrospray (ES) deposition system. The films were deposited in multiple steps without breaking the vacuum and characterized in situ using photoemission spectroscopy. The x-ray photoemission spectroscopy measurements indicate that the deposited layers are essentially contamination free and that subsequent depositions can be performed using the ES system without dissolving the previously deposited layers. Additional ultraviolet photoemission spectroscopy measurements showed the development of the highest occupied molecular-orbital structure as the MEH-PPV layer increased in thickness. This allowed the determination of the charge injection barriers (orbital alignment) at the Ag/MEH-PPV interface.

  4. Topaz and Kyanite Luminescence Under High Pressure

    NASA Astrophysics Data System (ADS)

    O'Bannon, E. F., III; Williams, Q. C.

    2014-12-01

    The luminescence spectra of Cr3+ in heat-treated topaz Al2SiO4(OH,F)2 and natural kyanite Al2SiO5 were measured from 650 - 800 nm in a hydrostatic environment up to pressures of 15 GPa. The R1 and R2 peaks of topaz shift at average rates of 0.30 nm/GPa and 0.22 nm/GPa, respectively, implying that the deformation of the Cr3+ octahedra increases with pressure. Three peaks are fit under each R line of topaz at both room and high pressure, and these peaks are associated with different Al sites into which the Cr substitutes. The shift of the R lines in topaz under pressure is remarkably linear, which appears to be a general feature of many Cr3+-bearing oxides: the underlying cause of this linearity may lie in anharmonic coupling with lattice vibrations. In this context, we also characterize the frequency shifts of two vibronic peaks within topaz. The R1 and R2 peaks of kyanite shift at 0.37 nm/GPa and 0.88 nm/GPa respectively. Two peaks are fit under R1 and three peaks are fit under R2 of kyanite at both room and high pressure; this result is also consistent with three different Cr3+ sites in this material. The R lines in kyanite are notably optically anisotropic, depending strongly on crystallographic orientation: this is most strongly manifested in the R2 peak. The Cr3+ luminescence in these materials provides a sensitive probe of pressure-dependent shifts in the local geometry of the Al-sites in these materials, which are analyzed in the context of previous single-crystal x-ray diffraction measurements.

  5. Spiropyran-based Photochromic Polymer Nanoparticles with Optically Switchable Luminescence

    PubMed Central

    Zhu, Ming-Qiang; Zhu, Linyong; Han, Jason J.; Wuwei, Wu; Hurst, James K.; Li, Alexander D. Q.

    2008-01-01

    Emulsion polymerization yields 40–400 nm diameter polymer nanoparticles with spiropyran-merocyanine dyes incorporated into their hydrophobic cavities; in contrast to their virtually nonfluorescent character in most environments, the merocyanine forms of the encapsulated dyes are highly fluorescent. Spiro-mero photoisomerization is reversible, allowing the fluorescence to be switched “on” and “off” by alternating UV and visible light. Immobilizing the dye inside hydrophobic pockets of nanoparticles also improves its photostability, rendering it more resistant than the same dyes in solution to fatigue effects arising from photochemical switching. The photophysical characteristics of the encapsulated fluorophores differ dramatically from those of the same species in solution, making nanoparticle-protected hydrophobic fluorophores attractive materials for potential applications such as optical data storage and switching and biological fluorescent labeling. To evaluate the potential for biological tagging, these optically addressable nanoparticles have been delivered into living cells and imaged with a liquid nitrogen cooled CCD. PMID:16569006

  6. Fabrication and properties of luminescence polymer composites with erbium/ytterbium oxides and gold nanoparticles

    PubMed Central

    Burunkova, Julia A; Denisiuk, Ihor Yu; Zhuk, Dmitri I; Daroczi, Lajos; Csik, Attila; Kokenyesi, Sándor

    2016-01-01

    Summary Rare-earth-doped optical materials are important for light sources in optoelectronics, as well as for efficient optical amplification elements and other elements of photonics. On the basis of the previously developed method of anhydrous, low-temperature synthesis of Er/Yb oxides from their chlorides we fabricated proper nanoparticles with defined parameters and used them for the development of optically transparent, luminescent polymer nanocomposite with low optical scattering, suitable for direct, light-induced formation of photonic elements. Introduction of preformed gold nanoparticles in such a nanocomposite was also performed and an enhancement of luminescence due to the influence of plasmon effects was detected. PMID:27335752

  7. A novel 2D porous indium coordination polymer with tunable luminescent property

    NASA Astrophysics Data System (ADS)

    Li, Xuejiao; Wang, Fangfang; Yang, He; Xu, Bo; Li, Cuncheng

    2016-08-01

    A new Indium coordination polymer [In(pda)1.5(phen)]n1 based on 1,4-phenylenediacetic acid (H2pda) and phen = 1,10-phenanthroline was obtained under hydrothermal condition and further characterized by single crystal X-ray analysis and other physicochemical studies such as infrared spectrum (IR), elemental analysis, thermogravimetric analysis (TGA) and powder X-ray diffraction (PXRD). Structure analysis reveals that complex 1 exhibits 2D porous (6,3) connected layer structure. Luminescent property of 1 was investigated both in the solid state and in different solvents and the results indicated that complex 1 demonstrates distinct solvent dependent luminescent property.

  8. Fabrication and properties of luminescence polymer composites with erbium/ytterbium oxides and gold nanoparticles.

    PubMed

    Burunkova, Julia A; Denisiuk, Ihor Yu; Zhuk, Dmitri I; Daroczi, Lajos; Csik, Attila; Csarnovics, István; Kokenyesi, Sándor

    2016-01-01

    Rare-earth-doped optical materials are important for light sources in optoelectronics, as well as for efficient optical amplification elements and other elements of photonics. On the basis of the previously developed method of anhydrous, low-temperature synthesis of Er/Yb oxides from their chlorides we fabricated proper nanoparticles with defined parameters and used them for the development of optically transparent, luminescent polymer nanocomposite with low optical scattering, suitable for direct, light-induced formation of photonic elements. Introduction of preformed gold nanoparticles in such a nanocomposite was also performed and an enhancement of luminescence due to the influence of plasmon effects was detected. PMID:27335752

  9. Polymer-Particle Pressure-Sensitive Paint with High Photostability.

    PubMed

    Matsuda, Yu; Uchida, Kenta; Egami, Yasuhiro; Yamaguchi, Hiroki; Niimi, Tomohide

    2016-01-01

    We propose a novel fast-responding and paintable pressure-sensitive paint (PSP) based on polymer particles, i.e. polymer-particle (pp-)PSP. As a fast-responding PSP, polymer-ceramic (PC-)PSP is widely studied. Since PC-PSP generally consists of titanium (IV) oxide (TiO₂) particles, a large reduction in the luminescent intensity will occur due to the photocatalytic action of TiO₂. We propose the usage of polymer particles instead of TiO₂ particles to prevent the reduction in the luminescent intensity. Here, we fabricate pp-PSP based on the polystyrene particle with a diameter of 1 μm, and investigate the pressure- and temperature-sensitives, the response time, and the photostability. The performances of pp-PSP are compared with those of PC-PSP, indicating the high photostability with the other characteristics comparable to PC-PSP. PMID:27092511

  10. Polymer-Particle Pressure-Sensitive Paint with High Photostability

    PubMed Central

    Matsuda, Yu; Uchida, Kenta; Egami, Yasuhiro; Yamaguchi, Hiroki; Niimi, Tomohide

    2016-01-01

    We propose a novel fast-responding and paintable pressure-sensitive paint (PSP) based on polymer particles, i.e. polymer-particle (pp-)PSP. As a fast-responding PSP, polymer-ceramic (PC-)PSP is widely studied. Since PC-PSP generally consists of titanium (IV) oxide (TiO2) particles, a large reduction in the luminescent intensity will occur due to the photocatalytic action of TiO2. We propose the usage of polymer particles instead of TiO2 particles to prevent the reduction in the luminescent intensity. Here, we fabricate pp-PSP based on the polystyrene particle with a diameter of 1 μm, and investigate the pressure- and temperature-sensitives, the response time, and the photostability. The performances of pp-PSP are compared with those of PC-PSP, indicating the high photostability with the other characteristics comparable to PC-PSP. PMID:27092511

  11. Luminescent AIE materials for high-performance sensing applications

    NASA Astrophysics Data System (ADS)

    Leung, Chris Wai Tung; Tang, Ben Zhong

    2014-10-01

    Luminescent materials have been widely applied in chemo- and bio-sensing applications because these luminescent materials offer high signal-to-background ratio, superior sensitivity and broad dynamic ranges in various detections. Conventional luminogens suffer from aggregation-caused quenching (ACQ) effect due to strong π-π stacking interaction upon aggregate formation of the luminogens with analytes. Such ACQ effect limits the scope of practical sensing applications. Luminogens with aggregation-induced emission (AIE) characteristics enjoy high emission efficiency in solid or aggregated state while they are non-emissive in solution. AIE luminogens (AIEgens) tackle the lethal problem of ACQ materials in the sensing applications. Siloles and tetraphenylethene (TPE) are archetypal AIE cores and possess advantages of facile synthesis and readily functionalization. AIEgens have been utilized to develop various fluorescent chemosensors. For example, hyperbranched AIE polymers with different topologies can be worked as turn-off explosive sensor with high sensitivity. The explosive detections can be done in solid film, which facilitates practical usage. The AIEgens can also be used as sensors for volatile organic compounds and metal ions through alternating fluorescence on/off mechanisms. Besides chemosensor, the AIEgens have been applied in the fields of biology. Water-soluble AIEgens have been developed for quantifying nucleic acids and proteins. They can serve as bioprobes for real-time monitoring and studying the kinetic of protein conformational changes, making them promising for diagnostic and therapeutic applications. These demonstrations significantly expand the scope of analysis applications of AIEgens and offer new strategies to the design of new fluorescent chemo- and bio-sensors.

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

    EPA Science Inventory

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

  13. Polymer beacons for luminescence and magnetic resonance imaging of DNA delivery.

    PubMed

    Bryson, Joshua M; Fichter, Katye M; Chu, Wen-Jang; Lee, Jing-Huei; Li, Jing; Madsen, Louis A; McLendon, Patrick M; Reineke, Theresa M

    2009-10-01

    The delivery of nucleic acids with polycations offers tremendous potential for developing highly specific treatments for various therapeutic targets. Although materials have been developed and studied for polynucleotide transfer, the biological mechanisms and fate of the synthetic vehicle has remained elusive due to the limitations with current labeling technologies. Here, we have developed polymer beacons that allow the delivery of nucleic acids to be visualized at different biological scales. The polycations have been designed to contain repeated oligoethyleneamines, for binding and compacting nucleic acids into nanoparticles, and lanthanide (Ln) chelates [either luminescent europium (Eu(3+)) or paramagnetic gadolinium (Gd(3+))]. The chelated Lns allow the visualization of the delivery vehicle both on the nm/microm scale via microscopy and on the sub-mm scale via MRI. We demonstrate that these delivery beacons effectively bind and compact plasmid (p)DNA into nanoparticles and protect nucleic acids from nuclease damage. These delivery beacons efficiently deliver pDNA into cultured cells and do not exhibit toxicity. Micrographs of cultured cells exposed to the nanoparticle complexes formed with fluorescein-labeled pDNA and the europium-chelated polymers reveal effective intracellular imaging of the delivery process. MRI of bulk cells exposed to the complexes formulated with pDNA and the gadolinium-chelated structures show bright image contrast, allowing visualization of effective intracellular delivery on the tissue-scale. Because of their versatility, these delivery beacons posses remarkable potential for tracking and understanding nucleic acid transfer in vitro, and have promise as in vivo theranostic agents. PMID:19805101

  14. Organo-lanthanide complexes as luminescent dopants in polymer waveguides fabricated by hot embossing

    NASA Astrophysics Data System (ADS)

    Moynihan, S.; Van Deun, R.; Binnemans, K.; Krueger, J.; von Papen, G.; Kewell, A.; Crean, G.; Redmond, G.

    2007-08-01

    Lanthanide complexes, Eu(dbm)3(Phen) and Er(dbm)3(Phen), are employed as luminescent dopants within polymer channel waveguide devices fabricated by hot embossing. Spectroscopic properties of the complexes as dopants in the waveguide core polymer are investigated in detail. Judd-Ofelt parameters are calculated for the europium chelate and radiative properties are determined viz. potential for optical amplification. Channel waveguides fabricated by single level embossing are shown to be capable of guiding visible and infrared light emitted following optical excitation of the dopants. Multi-level polymer micro-optical benches incorporating doped channel waveguides and passive locational features for self-alignment and integration of optical fibres are fabricated in a multi-level single-step embossing process and are shown to successfully out-couple the waveguided dopant emission.

  15. Coordination polymer core/shell structures: Preparation and up/down-conversion luminescence.

    PubMed

    Li, Bingmei; Xu, Hualan; Xiao, Chen; Shuai, Min; Chen, Weimin; Zhong, Shengliang

    2016-10-01

    Coordination polymer (CP) core-shell nanoparticles with Gd-based CP (GdCP) as core and Eu-based CP (EuCP) as shell have been successfully prepared. Allantoin was employed as the organic building block without the assistance of any template. The composition, size and structure of the core-shell nanospheres were well characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray (EDX), powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FT-IR), thermo-gravimetric analysis (TG). Results show that the resultant cores are uniform nanospheres with diameter of approximately 45nm, while the diameters of the core-shell nanospheres are increased to approximately 60nm. The core-shell products show enhanced luminescence efficiency than the core under 980nm laser excitation and decreased down-conversion luminescence when excited at 394nm. PMID:27344485

  16. Contribution of Increased Extraction Efficiency to Increased Photo-Luminescence in Strained Polymer Films

    NASA Astrophysics Data System (ADS)

    Chen, Po-Jui; Yang, Arnold Chang-Mou; Hsu, Jui-Hung; White, Jonathon D.

    2011-03-01

    Potential applications of Luminescent Conjugated Polymers in thin film diodes, solar cells and flat panel displays have been limited by low efficiency. Craze formation in MEH-PPV/polystyrene thin films leads to a factor of 2 or 3 increase in collected photo-luminescence (PL) due to a combination of factors such as MEH-PPV chain conformation and increased extraction efficiency of PL. In order to determine the contribution of the latter effect, we used Monte Carlo based Ray Tracing to analyze the trajectory of photons generated in the thin film under different strain conditions. Our results indicate that increased PL extraction due to the existence of crazes contributes ~ 50 % of the observed increase in PL, the majority of this being due to light emitted near the craze edges.

  17. Contribution of Increased Extraction Efficiency to Increased Photo-Luminescence in Strained Polymer Films

    NASA Astrophysics Data System (ADS)

    Chen, Po-Jui; Chang-Mou Yang, Arnold; Hsu, Jui-Hung; White, Jonathon D.

    2012-02-01

    Potential applications of Luminescent Conjugated Polymers in thin film diodes, solar cells and flat panel displays have been limited by low efficiency. Craze formation in MEH-PPV/polystyrene thin film leads to a factor of 2 or 3 increase in collected photo-luminescence (PL) due to a combination of factors such as MEH-PPV chain conformation and increased extraction efficiency of PL. In order to determine the contribution of the latter effect, we used Monte Carlo based Ray Tracing to analyze the trajectory of photons generated in the thin film under different strain conditions. Our results indicate that increased PL extraction due to the existence of crazes contributes ˜15% of the observed increase in PL, the majority of this being due to light emitted near the craze edges.

  18. Nucleotide/Tb³⁺ coordination polymer nanoparticles as luminescent sensor and scavenger for nitrite ion.

    PubMed

    Qi, Zewan; You, Qi; Chen, Yang

    2016-01-01

    Newly emerged metal organic coordination polymers have aroused the great interest in designing tailored functional materials. In this study, multiple functional components, luminescent Tb(3+) ion, nucleobase and antenna molecule, were integrated in a single material and prepared into a responsive nanoparticle for nitrite. The terbium coordination polymer nanoparticles made of this kind of material have the dual functions of recognition and transduction and obey a preset sensing mechanism without a post-functionalization of common materials. As the result of the tailored, the terbium coordination polymer nanoparticles are highly sensitive and selective to nitrite by means of Dexter energy transfer between Tb(3+) ion and nitrite, and can be used for the scavenger for nitrite in aqueous solution. The detection limit, dynamic range and removal capacity of U-Tb-OBBA CPNPs for nitrite are 0.3 µM, 0.3-470 µM and 4.44 mg per gram of particles, respectively. Metal organic coordination polymers show an attractive potential in constructing smart sensing materials. PMID:26703267

  19. Luminescent nanocomposites of conducting polymers and in-situ grown CdS quantum dots

    SciTech Connect

    Borriello, C.; Masala, S.; Nenna, G.; Minarini, C.; Di Luccio, T.; Bizzarro, V.; Re, M.; Pesce, E.

    2010-06-02

    Luminescent PVK:CdS and P3HT:CdS nanocomposites with enhanced electrooptical properties have been synthesized. The nucleation and growth of CdS nanoparticles have been obtained by the thermolysis of a single Cd and S precursor dispersed in the polymers. The size distribution and morphology of the nanoparticles have been studied by TEM analyses. Monodispersive and very small nanoparticles of diameter below 3 nm in PVK and 2 nm in P3HT, have been obtained. The application of such nanocomposites as emitting layers in OLED devices is discussed.

  20. Photon recycling across a ultraviolet-blocking layer by luminescence in polymer solar cells

    NASA Astrophysics Data System (ADS)

    Engmann, Sebastian; Machalett, Marie; Turkovic, Vida; Rösch, Roland; Rädlein, Edda; Gobsch, Gerhard; Hoppe, Harald

    2012-08-01

    UV-blocking layers can increase the long term stability of organic solar cell devices; however, they limit the amount of light that can be utilized for energy conversion. We present photon recycling and down-conversion via a luminescent layer across a UV-blocking TiO2 layer. Our results show that the use of an additional UV-blocking layer does not necessarily reduce the overall efficiency of organic solar cells, since the loss in photocurrent due to the UV-absorption loss can be partially compensated using high energy photon down-conversion via luminescence layers.

  1. Biocompatible polyester macroligands: new subunits for the assembly of star-shaped polymers with luminescent and cleavable metal cores.

    PubMed

    Corbin, P S; Webb, M P; McAlvin, J E; Fraser, C L

    2001-01-01

    The synthesis of a series of star-shaped, biocompatible polyesters--polylactides (PLAs), polycaprolactones (PCLs), and various copolymer analogues--with either labile iron(II) tris-bipyridyl or luminescent ruthenium(II) tris-bipyridyl cores is described. These polymers were readily assembled by a convergent, metal-template-assisted approach that entailed the synthesis of bipyridine (bpy) ligands incorporating PLA- and PCL-containing arms and subsequent chelation of the "macroligands" to iron(II) or ruthenium(II). Specifically, the polyester macroligands bpyPLA(2) and bpyPCL(2) were prepared by a stannous octoate catalyzed ring-opening polymerization of DL- or L-lactide and epsilon-caprolactone, using bis(hydroxymethyl)-2,2'-bipyridine as the initiator. Copolymers bpy(PCL-PLA)(2) and bpy(PLA-PCL)(2) were generated in an analogous manner using bpyPLA(2) and bpyPCL(2) as macroinitiators. Polymers with narrow molecular weight distributions and with molecular weights close to values expected based upon monomer/initiator loading were produced. The macroligands were subsequently chelated to iron(II) to afford six-armed, iron-core star polymers, which were characterized by UV-vis and (1)H NMR spectroscopy. Estimated chelation efficiencies for formation of the star polymers (M(n) calcd: 20-240 kDa) were high, as determined by UV-vis spectral analysis. Within the molecular weight range investigated, differential scanning calorimetry and thermogravimetric analysis revealed that the small amounts of metal in the polyester stars and differences in polymer architecture had little effect on the thermal properties of the PLA/PCL materials. However, thin films of the red-violet colored iron-core stars exhibited reversible, thermochromic bleaching. Solutions and films of the polymers also responded (with color loss) to a variety of chemical stimuli (e.g., acid, base, peroxides, ammonia), thus revealing potential for use in diverse sensing applications. Likewise, the polyester

  2. Synthesis, structure, luminescence and photocatalytic properties of an uranyl-2,5-pyridinedicarboxylate coordination polymer

    NASA Astrophysics Data System (ADS)

    Si, Zhen-Xiu; Xu, Wei; Zheng, Yue-Qing

    2016-07-01

    An uranium coordination polymer, namely [(UO2(pydc)(H2O)]·H2O (1) (H2pydc=2,5-pyridinedicarboxylic acid), has been obtained by hydrothermal method and characterized by X-ray single crystal structure determination. Structural analysis reveals that complex 1 exhibits 1D chain coordination polymer, in which UO22+ ions are bridged by 2,5-pyridinedicarboxylate ligands and the chains are connected into a 3D supramolecular network by O-H···O hydrogen bond interactions and π-π stacking interactions. The photocatalytic properties of 1 for degradation of methylene blue (MB), Rhodamine B (RhB) and methyl orange (MO) under Hg-lamp irradiation have been performed, and the amount of the catalyst as well as Hg-lamp irradiation with different power on the photodegradation efficiency of MB have been investigated. Elemental analyses, infrared spectroscopy, TG-DTA analyses and luminescence properties were also discussed.

  3. Structure and efficient luminescence upconversion of Ln(iii) aromatic N-oxide coordination polymers.

    PubMed

    Chong, Bowie S K; Moore, Evan G

    2016-08-14

    A series of lanthanide-based coordination polymers {[Yb1-xErx(4,4'-bpdo)3(H2O)2](CF3SO3)3}∞ were synthesised by solvent diffusion techniques, where 4,4'-bpdo = 4,4'-bipyridine-N,N'-dioxide, and using differing mole fractions of Yb(iii) and Er(iii) which were systematically varied (x = 0, 0.05, 0.20, 0.50 and 1). All of the materials obtained were characterised using elemental analyses, single-crystal X-ray diffraction (SXRD) and solid-state photoluminescence studies. Structurally, the coordination polymers crystallise as an isomorphous series of infinite 2D sheets, which contain two inner sphere water molecules, and are isostructural with a previously characterised homometallic Yb(iii) compound. In addition to the normal Near Infra-Red (NIR) luminescence, these compounds also demonstrate upconversion emission upon 980 nm excitation. Upconversion luminescence measurements reveal visible emission in the red, green, and blue regions corresponding to the (2)H11/2→(4)I15/2, (4)F9/2→(4)I15/2 and (2)H9/2→(4)I15/2 transitions of the Er(iii) cation upon two and three-photon excitation. We also observed weak emission from the Er(iii) cation in the UV region for the first time in a Ln-MOF based material. PMID:27411484

  4. Modern trends and development in high-dose luminescent measurements

    NASA Astrophysics Data System (ADS)

    Kortov, V.

    2014-11-01

    Main application areas of high-dose dosimetry are described. The requirements to the materials for high-dose luminescent detectors are set. The examples of successful high-dose measurements using radiation-resistant phosphors are given. Viability of using materials with deep traps to detect intensive radiation flows is grounded. Characteristics of high-dose measurements using highly sensitive detectors TLD-500 (Al2O3:C) and LiF:Mg,Cu,P are discussed.

  5. Self-assembly of highly luminescent heteronuclear coordination cages.

    PubMed

    Schmidt, Andrea; Hollering, Manuela; Han, Jiaying; Casini, Angela; Kühn, Fritz E

    2016-08-01

    Exo-functionalized Pd2L4 cage compounds with attached Ru(ii) pyridine complexes were prepared via coordination-driven self-assembly. Unlike most of the previously reported palladium(ii) cages, one of these metallocages exhibits an exceptionally high quantum yield of 66%. The presented approach is promising to obtain luminescent coordination complexes for various applications. PMID:27436541

  6. High-quantum efficiency, long-lived luminescing refractory oxides

    DOEpatents

    Chen, Y.; Gonzalez, R.; Summers, G.P.

    A crystal having a high-quantum efficiency and a long period of luminescence is formed of MgO or CaO and possessing a concentration ratio of H/sup -/ ions to F centers in the range of about 0.05 to about 10.

  7. High-quantum efficiency, long-lived luminescing refractory oxides

    DOEpatents

    Chen, Yok; Gonzalez, Roberto; Summers, Geoffrey P.

    1984-01-01

    A crystal having a high-quantum efficiency and a long period of luminescence is formed of an oxide selected from the group consisting of magnesium oxide and calcium oxide and possessing a concentration ratio of H.sup.- ions to F centers in the range of about 0.05 to about 10.

  8. High temperature polymer concrete

    DOEpatents

    Fontana, J.J.; Reams, W.

    1984-05-29

    This invention is concerned with a polymer concrete composition, which is a two-component composition useful with many bases including metal. Component A, the aggregate composition, is broadly composed of silica, silica flour, portland cement, and acrylamide, whereas Component B, which is primarily vinyl and acrylyl reactive monomers, is a liquid system.

  9. Ion and molecule sensors using molecular recognition in luminescent, conductive polymers. FY 1997 year-end progress report

    SciTech Connect

    Wasielewski, M.R.

    1997-01-01

    'The purpose of this project is to use molecular recognition strategies to develop sensor technology based on luminescent, conductive polymers that contain sites for binding specific molecules or ions in the presence of related molecules or ions. Selective binding of a particular molecule or ion of interest to these polymers will result in a large change in their luminescence and/or conductivity, which can be used to both qualitatively and quantitatively sense the presence of the bound molecules or ions. The main thrusts and accomplishments in the first year of this project involve developing polymer syntheses that yield conjugated polymers to which a wide variety of ligands for metal ion binding can be readily incorporated.'

  10. Multiplicative luminescence enhancement induced by chain relaxation in ultrathin films of a conjugated polymer (MEH-PPV)

    NASA Astrophysics Data System (ADS)

    Yang, Chih-Wei; Jou, Juo-Huei; Chang-Mou Yang, Arnold

    2006-03-01

    A surprising multiplication of light-emitting efficiency was observed in dewetting process of the conjugated luminescent polymer of poly (2-methoxy- 5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV). The luminescent efficiency increased with the dewetting process and became about six-fold when the polymer film ruptured into tiny droplets. This enhancement appeared to be related to the carrier transport mechanisms and the motions of polymer chains. The effects of inter-molecular energy transport and molecular deformation of polymer chains were studied by examining the emission behavior in liquid and solid solutions. It was found that the molecular movements during stretching in the glassy state were quite different from that in the dewetting process. The latter was dominated by disengagement of inter-molecular entanglements while the former was strongly influenced by trapping mechanisms of chain entanglements due to rapid local molecular strains. This work is supported by National Science Council of Taiwan.

  11. Luminescence of carbazolyl-containing polymers doped with iridium chelates

    NASA Astrophysics Data System (ADS)

    Skryshevskii, Yu. A.

    2008-05-01

    White light emission is shown to be obtainable at room temperature through the mixing of poly-N-vinylcarbazole (PVC) host fluorescence with fac-tris(2-phenylpyridyl)Ir(III) [Ir(ppy)3] and bis[2-(2'-benzothienyl)pyridinato-N,C3'](acetylacetonate)iridium (III) [Btp2Ir(acac)] dopant phosphorescence whereas at very low temperature through the superposition of poly-N-epoxypropyl-3,6-dibromocarbazole (3,6-DBrPEPC) host and Btp2Ir(acac) dopant phosphorescence emissions. The balance between basic colors is adjusted by the variation of triplet-emitter dopant concentrations. Spin-allowed singlet-singlet energy transfer from the host to iridium chelate dopants by the Forster mechanism is the dominant process in PVC. Spin-forbidden triplet-singlet transfer by the Forster mechanism from the host to the dopant occurs at low temperatures in 3,6-DBrPEPC due to strong spin-orbit coupling induced by the heavy bromine atoms. Spin-allowed transfer from the same host’s triplet excited state to the iridium chelate occurs via electron exchange at high temperatures.

  12. Phase states of water near the surface of a polymer membrane. Phase microscopy and luminescence spectroscopy experiments

    SciTech Connect

    Bunkin, N. F.; Gorelik, V. S.; Kozlov, V. A. Shkirin, A. V. Suyazov, N. V.

    2014-11-15

    Phase microscopy is used to show that the refractive index in the near-surface layer of water at the surface of a polymer Nafion membrane increases by a factor of 1.1 as compared to bulk water. Moreover, this layer exhibits birefringence. Experiments on UV irradiation of dry (anhydrous) and water-soaked Nafion are performed in grazing-incidence geometry to study their stimulated luminescence spectra. These spectra are found to be identical in both cases. For dry Nafion, luminescence can only be excited if probing radiation illuminates the polymer surface. The luminescence of water-soaked Nafion can also be excited if the distance between the optical axis and the surface is several hundred micrometers.

  13. High elastic modulus polymer electrolytes

    DOEpatents

    Balsara, Nitash Pervez; Singh, Mohit; Eitouni, Hany Basam; Gomez, Enrique Daniel

    2013-10-22

    A polymer that combines high ionic conductivity with the structural properties required for Li electrode stability is useful as a solid phase electrolyte for high energy density, high cycle life batteries that do not suffer from failures due to side reactions and dendrite growth on the Li electrodes, and other potential applications. The polymer electrolyte includes a linear block copolymer having a conductive linear polymer block with a molecular weight of at least 5000 Daltons, a structural linear polymer block with an elastic modulus in excess of 1.times.10.sup.7 Pa and an ionic conductivity of at least 1.times.10.sup.-5 Scm.sup.-1. The electrolyte is made under dry conditions to achieve the noted characteristics.

  14. Luminescent Lanthanide Reporters for High-Sensitivity Novel Bioassays.

    SciTech Connect

    Anstey, Mitchell; Fruetel, Julia A.; Foster, Michael E.; Hayden, Carl C.; Buckley, Heather L.; Arnold, John

    2013-09-01

    Biological imaging and assay technologies rely on fluorescent organic dyes as reporters for a number of interesting targets and processes. However, limitations of organic dyes such as small Stokes shifts, spectral overlap of emission signals with native biological fluorescence background, and photobleaching have all inhibited the development of highly sensitive assays. To overcome the limitations of organic dyes for bioassays, we propose to develop lanthanide-based luminescent dyes and demonstrate them for molecular reporting applications. This relatively new family of dyes was selected for their attractive spectral and chemical properties. Luminescence is imparted by the lanthanide atom and allows for relatively simple chemical structures that can be tailored to the application. The photophysical properties offer unique features such as narrow and non-overlapping emission bands, long luminescent lifetimes, and long wavelength emission, which enable significant sensitivity improvements over organic dyes through spectral and temporal gating of the luminescent signal.Growth in this field has been hindered due to the necessary advanced synthetic chemistry techniques and access to experts in biological assay development. Our strategy for the development of a new lanthanide-based fluorescent reporter system is based on chelation of the lanthanide metal center using absorbing chromophores. Our first strategy involves %22Click%22 chemistry to develop 3-fold symmetric chelators and the other involves use of a new class of tetrapyrrole ligands called corroles. This two-pronged approach is geared towards the optimization of chromophores to enhance light output.

  15. Evaluation of high temperature polymers

    NASA Technical Reports Server (NTRS)

    Jayaraj, K.; Dorogy, W.; Farrell, B.; Landrau, N.

    1995-01-01

    The purpose of this paper is to identify and develop arc-track resistant insulation materials that can operate reliably at 300 C. In the first phase, high performance polymers are evaluated based on structure, thermal stability and electrical properties. Next, the polymers are ranked according to performance and experimental characterization. Then, experimental evaluations in wire configuration are conducted. And selection is made based on performance and commerical potential.

  16. Highly luminescent Ag+ nanoclusters for Hg2+ ion detection

    NASA Astrophysics Data System (ADS)

    Yuan, Xun; Yeow, Teik Jin; Zhang, Qingbo; Lee, Jim Yang; Xie, Jianping

    2012-03-01

    A simple, low-cost and label-free Hg2+ ion sensor has been developed by using novel luminescent Ag+ nanoclusters (NCs) with an excellent optical property (quantum yield = 15%), an ultra-high ratio of active Ag+ species in the NC surface (~100%), and an ultra-short diffusion path length of Hg2+ ions to access the NC surface (~0.5 nm).A simple, low-cost and label-free Hg2+ ion sensor has been developed by using novel luminescent Ag+ nanoclusters (NCs) with an excellent optical property (quantum yield = 15%), an ultra-high ratio of active Ag+ species in the NC surface (~100%), and an ultra-short diffusion path length of Hg2+ ions to access the NC surface (~0.5 nm). Electronic supplementary information (ESI) available: Experimental details of the synthesis of b-Ag NCs; time-resolved evolution of photoemission spectra of the b-Ag NCs in toluene; photoexcitation spectrum of the b-Ag NCs in toluene; comparison of the luminescence of b-Ag NCs at different temperatures (4 and 25 °C) TEM image of the b-Ag NCs in toluene; optical properties of r-Ag NCs obtained by the reduction of b-Ag NCs in toluene; XPS spectra of b-Ag NCs, thiolate-Ag+ complexes, r-Ag NCs, and large Ag nanoparticles; TEM image of the Hg2+-Ag NCs; photostability of the b-Ag NCs; tolerance studies of the b-Ag NCs over other metal ions; tolerance studies of the b-Ag NCs over common thiol ligands (e.g., GSH) and anions; relative luminescence of the b-Ag NCs in different real water samples in the presence of Hg2+ ions; and relative luminescence of the b-Ag NCs in NaCl solution with different concentrations. See DOI: 10.1039/c2nr11999d

  17. Dual-Mode Luminescence Modulation upon Visible-Light-Driven Photochromism with High Contrast for Inorganic Luminescence Ferroelectrics.

    PubMed

    Zhang, Qiwei; Zheng, Xuewen; Sun, Haiqin; Li, Wenqing; Wang, Xusheng; Hao, Xihong; An, Shengli

    2016-02-01

    A luminescence ferroelectric oxide, Na(0.5)Bi(2.5)Nb2O9 (NBN), system with bismuth layer structure introduced by lanthanide ion (Er(3+)) has been demonstrated to exhibit reversible, high-contrast luminescence modulation (95%) and excellent fatigue resistance based on visible-light-driven photochromism (407 nm or sunlight). The coloration and decoloration process can be effectively read out by dual modes, upconversion and downshifting, and reversibly converted between green and dark gray by alternating visible light or sunlight irradiation and thermal stimulus. The luminescence modulation degree upon photochromic reactions is strongly dependent upon irradiation light wavelength and irradiation time. After undergoing several cycles, there are no significant degradations, showing high reversibility. Considering its high-contrast photoswitchable luminescence feature and intrinsic ferroelectricity of NBN host, NBN-based multifunctional materials can be suggested as a promising candidate for new potentials in photonic storage and optoelectronic multifunctional devices. PMID:26820999

  18. Synthesis, crystal structure and luminescence properties of lanthanide coordination polymers with a new semirigid bridging thenylsalicylamide ligand

    SciTech Connect

    Song, Xue-Qin Wang, Li; Zhao, Meng-Meng; Wang, Xiao-Run; Peng, Yun-Qiao; Cheng, Guo-Quan

    2013-09-15

    Two new lanthanide coordination polymers based on a semirigid bridging thenylsalicylamide ligand ([Ln{sub 2}L{sub 3}(NO{sub 3}){sub 6}]·(C{sub 4}H{sub 8}O{sub 2}){sub 2}){sub ∞} were obtained and characterized by elemental analysis, X-ray diffraction, IR and TGA measurements. The two compounds are isostructure and possess one dimensional trapezoid ladder-like chain built up from the connection of isolated LnO{sub 3}(NO{sub 3}){sub 3} polyhedra (distorted monocapped antisquare prism) through the ligand. The photoluminescence analysis suggest that there is an efficient ligand-to-Ln(III) energy transfer in Tb(III) complex and the ligand is an efficient “antenna” for Tb(III). From a more general perspective, the results demonstrated herein provide the possibility of controlling the formation of the desired lanthanide coordination structure to enrich the crystal engineering strategy and enlarge the arsenal for developing excellent luminescent lanthanide coordination polymers. - Graphical abstract: We present herein one dimensional lanthanide coordination polymers of a new semirigid exo-bidentate ligand which not only display interesting structures but also possess strong luminescence properties. Display Omitted - Highlights: • We present lanthanide coordination polymers of a new semirigid exo-bidentate ligand. • The lanthanide coordination polymers exhibit interesting structures. • The luminescent properties of Tb(III) complexes are discussed in detail.

  19. Luminescent optical detection of volatile electron deficient compounds by conjugated polymer nanofibers.

    PubMed

    Wade, Aidan; Lovera, Pierre; O'Carroll, Deirdre; Doyle, Hugh; Redmond, Gareth

    2015-04-21

    Optical detection of volatile electron deficient analytes via fluorescence quenching is demonstrated using ca. 200 nm diameter template-synthesized polyfluorene nanofibers as nanoscale detection elements. Observed trends in analyte quenching effectiveness suggest that, in addition to energetic factors, analyte vapor pressure and polymer/analyte solubility play an important role in the emission quenching process. Individual nanofibers successfully act as luminescent reporters of volatile nitroaromatics at sub-parts per million levels. Geometric factors, relating to the nanocylindrical geometry of the fibers and to low nanofiber substrate coverage, providing a less crowded environment around fibers, appear to play a role in providing access by electron deficient quencher molecules to the excited states within the fibers, thereby facilitating the pronounced fluorescence quenching response. PMID:25803242

  20. Two new luminescent Zn(II) coordination polymers with different interpenetrated motifs

    NASA Astrophysics Data System (ADS)

    Song, Changying; Liu, Qifeng; Liu, Wei; Cao, Ziqing; Ren, Yuanyuan; Zhou, Qichao; Zhang, Li

    2015-11-01

    Solvothermal reactions of Zn(NO3)2, H2tdc and bib in the presence of different solvents (DMF = N,N'- dimethylformamide or DMA = N,N'- dimethylacetamide) have given rise to two new coordination polymers, namely [Zn2(tdc)2(bib)2]n·2n(H2O) (1) and [Zn(tdc)(bib)0.5(H2O)]n (2) (H2tdc = 2,5-thiophenedicarboxylic acid, bib = 1, 4-bis(imidazolyl)butane). The structures were determined by single crystal X-ray diffraction and characterized by elemental analysis, powder X-ray diffraction and infrared spectroscopy. Compound 1 exhibits a 4-fold interpenetrated dia topological network, and compound 2 features a 8-fold interpenetrated ths topological network. In addition, thermal stabilities and solid state luminescent properties of these two compounds were also investigated.

  1. Luminescent lanthanide coordination polymers synthesized via in-situ hydrolysis of dimethyl-3,4-furandicarboxylate

    NASA Astrophysics Data System (ADS)

    Greig, Natalie E.; Einkauf, Jeffrey D.; Clark, Jessica M.; Corcoran, Eric J.; Karram, Joseph P.; Kent, Charles A.; Eugene, Vadine E.; Chan, Benny C.; de Lill, Daniel T.

    2015-05-01

    Dimethyl-3,4-furandicarboxylate undergoes hydrolysis under hydrothermal conditions with lanthanide (Ln) ions to form two-dimensional coordination polymers, [Ln(C6H2O5)(C6H3O5)(H2O)]n (Ln=Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu). The resulting materials exhibit luminescent properties with quantum yields and lifetimes for the Eu(III) and Tb(III) compounds of 1.1±0.3% and 0.387±0.0001 ms, and 3.3±0.8% and 0.769±0.006 ms, respectively. Energy values for the singlet and triplet states were determined for dimethyl-3,4-furandicarboxylate and 3,4-furandicarboxylic acid. Excited state dynamics and structural features are examined to explicate the reported quantum yields. A series of other FDC structures is briefly presented.

  2. Influence of ZnO nanorod on the luminescent and electrical properties of fluorescent dye-doped polymer nanocomposite

    NASA Astrophysics Data System (ADS)

    Zhang, T.; Xu, Z.; Qian, L.; Tao, D. L.; Teng, F.; Xu, X. R.

    2006-11-01

    The luminescent properties of fluorescent dye-doped polymer dispersed with ZnO nanorods were investigated. Embedding ZnO nanorods in blend film results in a blue-shifted emission of fluorescent dye. It is accounted for in terms of the difference in permittivity between inorganic oxide nano-material and dye-doped polymer. Moreover, polymer light-emitting diodes with the addition of ZnO nanorods showed the lower threshold voltage and the higher charge current and electroluminescence efficiency.

  3. High Temperature Polymer Matrix Composites

    NASA Technical Reports Server (NTRS)

    1985-01-01

    These are the proceedings of the High Temperature Polymer Matrix Composites Conference held at the NASA Lewis Research Center on March 16 to 18, 1983. The purpose of the conference is to provide scientists and engineers working in the field of high temperature polymer matrix composites an opportunity to review, exchange, and assess the latest developments in this rapidly expanding area of materials technology. Technical papers are presented in the following areas: (1) matrix development; (2) adhesive development; (3) characterization; (4) environmental effects; and (5) applications.

  4. "Green" High-Temperature Polymers

    NASA Technical Reports Server (NTRS)

    Meador, Michael A.

    1998-01-01

    PMR-15 is a processable, high-temperature polymer developed at the NASA Lewis Research Center in the 1970's principally for aeropropulsion applications. Use of fiber-reinforced polymer matrix composites in these applications can lead to substantial weight savings, thereby leading to improved fuel economy, increased passenger and payload capacity, and better maneuverability. PMR-15 is used fairly extensively in military and commercial aircraft engines components seeing service temperatures as high as 500 F (260 C), such as the outer bypass duct for the F-404 engine. The current world-wide market for PMR-15 materials (resins, adhesives, and composites) is on the order of $6 to 10 million annually.

  5. Measurement of luminescence decays: High performance at low cost

    NASA Astrophysics Data System (ADS)

    Sulkes, Mark; Sulkes, Zoe

    2011-11-01

    The availability of inexpensive ultra bright LEDs spanning the visible and near-ultraviolet combined with the availability of inexpensive electronics equipment makes it possible to construct a high performance luminescence lifetime apparatus (˜5 ns instrumental response or better) at low cost. A central need for time domain measurement systems is the ability to obtain short (˜1 ns or less) excitation light pulses from the LEDs. It is possible to build the necessary LED driver using a simple avalanche transistor circuit. We describe first a circuit to test for small signal NPN transistors that can avalanche. We then describe a final optimized avalanche mode circuit that we developed on a prototyping board by measuring driven light pulse duration as a function of the circuit on the board and passive component values. We demonstrate that the combination of the LED pulser and a 1P28 photomultiplier tube used in decay waveform acquisition has a time response that allows for detection and lifetime determination of luminescence decays down to ˜5 ns. The time response and data quality afforded with the same components in time-correlated single photon counting are even better. For time-correlated single photon counting an even simpler NAND-gate based LED driver circuit is also applicable. We also demonstrate the possible utility of a simple frequency domain method for luminescence lifetime determinations.

  6. Highly cross-linked nanoporous polymers

    DOEpatents

    Steckle, Jr., Warren P.; Apen, Paul G.; Mitchell, Michael A.

    1997-01-01

    Condensation polymerization followed by a supercritical extraction step can be used to obtain highly cross-linked nanoporous polymers with high surface area, controlled pore sizes and rigid structural integrity. The invention polymers are useful for applications requiring separation membranes.

  7. Highly cross-linked nanoporous polymers

    DOEpatents

    Steckle, Jr., Warren P.; Apen, Paul G.; Mitchell, Michael A.

    1998-01-01

    Condensation polymerization followed by a supercritical extraction step can be used to obtain highly cross-linked nanoporous polymers with high surface area, controlled pore sizes and rigid structural integrity. The invention polymers are useful for applications requiring separation membranes.

  8. High-temperature polymer matrix composites

    NASA Technical Reports Server (NTRS)

    Meador, Michael A.

    1990-01-01

    Polymers research at the NASA Lewis Research Center has produced high-temperature, easily processable resin systems, such as PMR-15. In addition, the Polymers Branch has investigated ways to improve the mechanical properties of polymers and the microcracking resistance of polymer matrix composites in response to industry need for new and improved aeropropulsion materials. Current and future research in the Polymers Branch is aimed at advancing the upper use temperature of polymer matrix composites to 700 F and beyond by developing new resins, by examining the use of fiber reinforcements other than graphite, and by developing coatings for polymer matrix composites to increase their oxidation resistance.

  9. High-brightness source based on luminescent concentration.

    PubMed

    de Boer, Dick K G; Bruls, Dominique; Jagt, Henri

    2016-07-11

    The concept of a high-luminance light source based on luminescent conversion of LED light and optical concentration in a transparent phosphor is explained. Experiments on a realized light source show that a luminous flux of 8500 lm and a luminance of 500 cd/mm2 can be attained using 56 pump LEDs at 330 W electrical input power. The measurement results are compared to optical simulations, showing that the experimental optical efficiency is slightly lower than expected. The present status enables applications like mid-segment digital projection using LED technology, whereas the concept is scalable to higher fluxes. PMID:27410894

  10. Syntheses, structures and luminescence properties of lanthanide coordination polymers with helical character

    SciTech Connect

    Zhou Ruisha; Cui Xiaobing; Song Jiangfeng; Xu Xiaoyu; Xu Jiqing Wang Tiegang

    2008-08-15

    A series of lanthanide coordination polymers, (Him){sub n}[Ln(ip){sub 2}(H{sub 2}O)]{sub n} [Ln=La(1), Pr(2), Nd(3) and Dy(4), H{sub 2}ip=isophthalic acid, im=imidazole] and [Y{sub 2}(ip){sub 3}(H{sub 2}O){sub 2}]{sub n}.nH{sub 2}O (5), have been synthesized and characterized by elemental analyses, infrared (IR), ultraviolet-visible-near infrared (UV-Vis-NIR) and single-crystal X-ray diffraction analyses. The isostructural compounds 1-4 possess 3-D structures with three different kinds of channels. Compound 5 features a 2-D network making of two different kinds of quadruple-helical chains. Compounds 2 and 3 present the characteristic emissions of Pr(III) and Nd(III) ions in NIR region, respectively. Compound 4 shows sensitized luminescence of Dy(III) ions in visible region. - Graphical abstract: A series of lanthanide coodination polymers, (Him){sub n}[Ln(ip){sub 2}(H{sub 2}O)]{sub n} [Ln=La(1), Pr(2), Nd(3) and Dy(4)] and [Y{sub 2}(ip){sub 3}(H{sub 2}O){sub 2}]{sub n}.nH{sub 2}O (5), have been reported. The isostructural compounds 1-4 possess 3-D structures with three different kinds of channels. Compound 5 displays a 2-D network making of two kinds of quadruple-helical chains. Display Omitted.

  11. Tension in Highly Branched Polymers

    NASA Astrophysics Data System (ADS)

    Rubinstein, Michael

    2012-02-01

    We propose a systematic method of designing branched macromolecules capable of building up high tension in their covalent bonds, which can be controlled by changing solvent quality. This tension is achieved exclusively due to intramolecular interactions by focusing lower tensions from its numerous branches to a particular section of the designed molecule. The simplest molecular architecture, which allows this tension amplification, is a so-called pom-pom macromolecule consisting of a relatively short linear spacer and two z-arm stars at its ends. Tension developed in the stars due to crowding of their branches is amplified by a factor of z and focused to the spacer. There are other highly branched macromolecules, such as molecular brushes - comb polymers with high density of side branches, that have similar focusing and amplification properties. In addition molecular brushes transmit tension along their backbone. Adsorption or grafting of these branched molecules on a substrate results in further increase in tension as compared to molecules in solution. Molecular architectures similar to pom-pom and molecular brushes with a high tension amplification parts can be used in numerous sensor applications. Unique conformations of molecular brushes in a pre-wetting layer allow direct visualization by atomic force microscope. Detailed images of individual molecules spreading along the surface enable critical evaluation of theories of chain dynamics in polymer monolayer. Strong spreading of densely branched macromolecules on a planar substrate can lead to high tension in the molecular backbone sufficient to break covalent bonds.

  12. Exceptional Oxygen Sensing Properties of New Blue Light-Excitable Highly Luminescent Europium(III) and Gadolinium(III) Complexes

    PubMed Central

    Borisov, Sergey M.; Fischer, Roland; Saf, Robert; Klimant, Ingo

    2016-01-01

    New europium(III) and gadolinium(III) complexes bearing 8-hydroxyphenalenone antenna combine efficient absorption in the blue part of the spectrum and strong emission in polymers at room temperature. The Eu(III) complexes show characteristic red luminescence whereas the Gd(III) dyes are strongly phosphorescent. The luminescence quantum yields are about 20% for the Eu(III) complexes and 50% for the Gd(III) dyes. In contrast to most state-of-the-art Eu(III) complexes the new dyes are quenched very efficiently by molecular oxygen. The luminescence decay times of the Gd(III) complexes exceed 1 ms which ensures exceptional sensitivity even in polymers of moderate oxygen permeability. These sensors are particularly suitable for trace oxygen sensing and may be good substitutes for Pd(II) porphyrins. The photophysical and sensing properties can be tuned by varying the nature of the fourth ligand. The narrow-band emission of the Eu(III) allows efficient elimination of the background light and autofluorescence and is also very attractive for use e.g. in multi-analyte sensors. The highly photostable indicators incorporated in nanoparticles are promising for imaging applications. Due to the straightforward preparation and low cost of starting materials the new dyes represent a promising alternative to the state-of-the-art oxygen indicators particularly for such applications as e.g. food packaging. PMID:27158252

  13. Understanding the Structure of Reversible Coordination Polymers Based on Europium in Electrostatic Assemblies Using Time-Resolved Luminescence.

    PubMed

    Xu, Limin; Xie, Mengqi; Huang, Jianbin; Yan, Yun

    2016-06-14

    In situ characterization of the structure of reversible coordination polymers remains a challenge because of their dynamic and concentration-responsive nature. It is especially difficult to determine these structures in their self-assemblies where their degree of polymerization responds to the local concentration. In this paper, we report on the structure of reversible lanthanide coordination polymers in electrostatic assemblies using time-resolved luminescence (TRL) measurement. The reversible coordinating system is composed of the bifunctional ligand 1,11-bis(2,6-dicarboxypyridin-4-yloxy)-3,6,9-trioxaundecane (L2EO4) and europium ion Eu(3+). Upon mixing with the positively charged diblock copolymer poly(2-vinylpyridine)-b-poly(ethylene oxide) (P2VP41-b-PEO205), electrostatic polyion micelles are formed and the negatively charged L2EO4-Eu coordination complex simultaneously transforms into coordination "polymers" in the micellar core. By virtue of the water-sensitive luminescence of Eu(3+), we are able to obtain the structural information of the L2EO4-Eu coordination polymers before and after the formation of polyion micelles. Upon analyzing the fluorescence decay curves of Eu(3+) before and after micellization, the fraction of Eu(3+) fully coordinated with L2EO4 is found to increase from 32 to 83%, which verifies the occurrence of chain extension of the L2EO4-Eu coordination polymers in the micellar core. Our work provides a qualitative picture for the structure change of reversible coordination polymers, which allows us to look into these "invisible" structures. PMID:27228142

  14. Tuning structural topologies of two new luminescent Zn(II) coordination polymers via varying organic carboxylate ligands

    NASA Astrophysics Data System (ADS)

    Zhang, Yan; Liu, Qi-Feng; Xing, Guang'en; Zhang, Zhong-Qiang

    2015-04-01

    Presented here are two new luminescent Zn(II) coordination polymers, [Zn3(pdc)3(Hmtz)]n (1) and [Zn3(ntd)(mtz)4(DMA)2]n (2) (H2pdc = terephthalic acid, H2ntd = 2,6-naphthalenedicarboxylic acid, Hmtz = 5-methyl-1H-tetrazole). Single crystal X-ray diffraction analysis reveals that compound 1 features a 8-connected hex topological framework with the schläfli symbol of {36.418.53.6}, while compound 2 features a (3,4)-connected tfi topological framework with the schläfli symbol of {62.84}{62.8}2. The thermal stabilities and luminescent properties of 1-2 were also investigated.

  15. Crystal structures and luminescent properties of lanthanide nitrate coordination polymers with structurally related amide type bridging podands

    SciTech Connect

    Wang, Qing; Yan, Xuhuan; Zhang, Hongrui; Liu, Weisheng; Tang, Yu; Tan, Minyu

    2011-01-15

    A one-dimensional linear chain coordination polymer [ErL{sup I}(NO{sub 3}){sub 3}(CH{sub 3}CO{sub 2}Et)]{sub n} (L{sup I}=1,2-bis{l_brace}[(2'-furfurylaminoformyl)phenoxyl]methyl{r_brace}benzene) and a one-dimensional zig-zag coordination polymer {l_brace}[TbL{sup II}(NO{sub 3}){sub 3}(H{sub 2}O)].(H{sub 2}O){r_brace}{sub n} (L{sup II}=1,2-bis{l_brace}[2'-(2-pyridylmethylaminoformyl)phenoxyl]methyl{r_brace}benzene) were assembled by two structurally related bridging podands L{sup I} and L{sup II} which have uniform skeleton and different terminal groups. In {l_brace}[TbL{sup II}(NO{sub 3}){sub 3}(H{sub 2}O)].(H{sub 2}O){r_brace}{sub n}, the neutral chains were linked by the hydrogen bonding interactions between the free and coordinated water molecules from two different directions to interpenetrate into a 3D supramolecular structure. At the same time, the luminescent properties of the solid Tb(III) nitrate complexes of these podands were investigated at room temperature. The lowest triplet state energy levels T{sub 1} of the podands L{sup I} and L{sup II} indicate that the triplet state energy levels of the antennae are both above the lowest excited resonance level of {sup 5}D{sub 4} of Tb{sup 3+} ion. Thus the absorbed energy could be transferred from ligands to the central Tb{sup 3+} ions. And the influence of the hydrogen bonding on the luminescence efficiencies of the coordination polymers was also discussed. -- Graphical Abstract: Two one-dimensional lanthanide coordination polymers were assembled by two structurally related bridging podands, and the effects of the structures on luminescent properties of the solid Tb(III) nitrate complexes were investigated. Display Omitted Research highlights: > Two structurally related amide type bridging ligands were designed and synthesized. > Two one dimensional lanthanide nitrate coordination polymers were obtained. > The structure effects on luminescent properties of the terbium complexes were discussed.

  16. Surface modification of luminescent lanthanide phosphate nanorods with cationic "Quat-primer" polymers.

    PubMed

    Komban, Rajesh; Beckmann, Ralph; Rode, Sebastian; Ichilmann, Sachar; Kühnle, Angelika; Beginn, Uwe; Haase, Markus

    2011-08-16

    "Quat-primer" polymers bearing cationic groups were investigated as a surface modifier for Tb-doped cerium phosphate green-emitting fluorescent nanorods (NRs). The NRs were synthesized by a microwave process without using any complex agents or ligands and were characterized with different analytical tools such as X-ray diffraction, transmission electron microscopy, and fluorescence spectroscopy. Poly(ethyleneimine) partially quarternized with glycidyltrimethylammonium chloride was synthesized separately and characterized in detail. (1)H and (13)C NMR spectroscopic studies revealed that the quaternary ammonium group was covalently attached to the polymer. UV-vis spectroscopy was used to examine the stability of the colloidal dispersions of the bare NRs as well as the modified NRs. ζ potential, thermogravimetric analysis, and atomic force microscopy studies were carried out to confirm that the positively charged Quat-primer polymer is adsorbed on the negatively charged surface of the NRs, which results in high dispersion stability. Emission spectra of the modified NRs indicated that there was no interference of the Quat-primer polymer with the fluorescence behavior. PMID:21721577

  17. Tunable, broadband and high-efficiency Si/Ge hot luminescence with plasmonic nanocavity array

    NASA Astrophysics Data System (ADS)

    Qi, Gongmin; Zhang, Miao; Wang, Lin; Mu, Zhiqiang; Ren, Wei; Li, Wei; Di, Zengfeng; Wang, Xi

    2016-06-01

    In addition to the massive application in the electronics industry for decades, silicon has been considered as one of the best candidates for the photonics industry. However, a high-efficiency, broadband light source is still a challenge. In this paper, we theoretically propose a Si/Ge based platform consisting of plasmonic nanocavity array to realize the tunable, broadband, and high-efficiency Si/Ge hot luminescence from infrared to visible region with large luminescence enhancement (about 103). It is demonstrated that the large luminescence enhancement is due to the resonance between the intrinsic hot luminescence and the plasmonic nanocavity modes with ultra-small effective mode volumes. And, the size and Ge composition of Si 1 - x Ge x nanowire can be tuned to realize the tunable and broadband luminescence. This study gives rise to many applications in silicon photonics, like ultrafast optical communications, sensors, and on-chip spectral measurements.

  18. A novel cobalt (I) coordination polymer with mixed thiocyanate and quinoline ligands: crystal structure, magnetism and luminescent properties.

    PubMed

    Li, Lei; Chen, Shuai; Zhou, Rui-Min; Bai, Yan; Dang, Dong-Bin

    2014-01-01

    A new Co(I) one-dimensional coordination polymer [Co(SCN)(ql)]n (ql=quinoline) (1) has been synthesized and characterized by IR, elemental analysis, TG technique and X-ray crystallography. Co(I) atom has a distorted trigonal pyramidal N2S2 (1) environment with two S atoms and one N atom from three μ-1,1,3-thiocyanate bridge ligands and one N atom from ql ligand. Two S atoms from two μ-1,1,3-SCN- bridging ligands bridge two centers to obtain bimetallic 4-membered ring. Adjacent 4-membered rings are linked by a pair of μ-1,1,3-SCN- bridging ligands to form a 1D stair-case like chain. The luminescent properties and magnetic properties of the polymer 1 were investigated in the solid state. PMID:24211622

  19. Controllable Synthesis of Highly Luminescent Boron Nitride Quantum Dots.

    PubMed

    Li, Hongling; Tay, Roland Yingjie; Tsang, Siu Hon; Zhen, Xu; Teo, Edwin Hang Tong

    2015-12-22

    Boron nitride quantum dots (BNQDs), as a new member of heavy metal-free quantum dots, have aroused great interest in fundamental research and practical application due to their unique physical/chemical properties. However, it is still a challenge to controllably synthesize high-quality BNQDs with high quantum yield (QY), uniform size and strong fluorescent. In this work, BNQDs have been successfully fabricated by the liquid exfoliation and the subsequent solvothermal process with respect to its facileness and easy large scale up. Importantly, BNQDs with high-quality can be controllably obtained by adjusting the synthetic parameters involved in the solvothermal process including filling factor, synthesis temperature, and duration time. Encouragingly, the as-prepared BNQDs possess strong blue luminescence with QY as high as 19.5%, which can be attributed to the synergetic effect of size, surface chemistry and edge defects. In addition, this strategy presented here provides a new reference for the controllable synthesis of other heavy metal-free QDs. Furthermore, the as-prepared BNQDs are non-toxic to cells and exhibit nanosecond-scaled lifetimes, suggesting they have great potential biological and optoelectronic applications. PMID:26574683

  20. Charged polymers in high dimensions

    NASA Technical Reports Server (NTRS)

    Kantor, Yacov

    1990-01-01

    A Monte Carlo study of charged polymers with either homogeneously distributed frozen charges or with mobile charges has been performed in four and five space dimensions. The results are consistent with the renormalization-group predictions and contradict the predictions of Flory-type theory. Introduction of charge mobility does not modify the behavior of the polymers.

  1. Development of a novel terbium(III) chelate-based luminescent probe for highly sensitive time-resolved luminescence detection of hydroxyl radical.

    PubMed

    Cui, Guanfeng; Ye, Zhiqiang; Chen, Jinxue; Wang, Guilan; Yuan, Jingli

    2011-05-15

    Time-resolved (or time-gated) luminescence detection technique using lanthanide chelates as luminescent probes is a widely used and highly sensitive method for the biological applications. The developments of various functional lanthanide probes that can selectively recognize the biological targets are the essential objective of the technique. In this work, a unique Tb(3+) chelate-based luminescent probe, N,N,N(1),N(1)-[2,6-bis(3'-aminomethyl-1'-pyrazolyl)-4-(p-aminophenoxy)methylene-pyridine] tetrakis(acetate)-Tb(3+)(BMPTA-Tb(3+)), has been designed and synthesized for highly selective and sensitive time-resolved luminescence detection of one highly reactive oxygen species (ROS), hydroxyl radical (OH). The probe is almost non-luminescent, and can selectively react with hydroxyl radical to afford a highly luminescent Tb(3+) chelate, N,N,N(1),N(1)-[2,6-bis(3'-aminomethyl-1'-pyrazolyl)-4-hydroxymethyl-pyridine] tetrakis(acetate)-Tb(3+) (BHTA-Tb(3+)), accompanied by a 49-fold increase in luminescence quantum yield with a long luminescence lifetime (2.76 ms). The luminescence response of the probe to hydroxyl radical is highly selective and insensitive to pH in the physiological pH range. For loading the probe into the living cells, the acetoxymethyl ester of BMPTA-Tb(3+) was synthesized and used for the HeLa cell loading. Based on this probe, a background-free time-resolved luminescence imaging method for detecting hydroxyl radical in living cells was successfully established. PMID:21482311

  2. Highly cross-linked nanoporous polymers

    DOEpatents

    Steckle, W.P. Jr.; Apen, P.G.; Mitchell, M.A.

    1998-01-20

    Condensation polymerization followed by a supercritical extraction step can be used to obtain highly cross-linked nanoporous polymers with high surface area, controlled pore sizes and rigid structural integrity. The invention polymers are useful for applications requiring separation membranes. 1 fig.

  3. Tough, High-Performance, Thermoplastic Addition Polymers

    NASA Technical Reports Server (NTRS)

    Pater, Ruth H.; Proctor, K. Mason; Gleason, John; Morgan, Cassandra; Partos, Richard

    1991-01-01

    Series of addition-type thermoplastics (ATT's) exhibit useful properties. Because of their addition curing and linear structure, ATT polymers have toughness, like thermoplastics, and easily processed, like thermosets. Work undertaken to develop chemical reaction forming stable aromatic rings in backbone of ATT polymer, combining high-temperature performance and thermo-oxidative stability with toughness and easy processibility, and minimizing or eliminating necessity for tradeoffs among properties often observed in conventional polymer syntheses.

  4. Highly luminescent half-lantern cyclometalated platinum(II) complex: synthesis, structure, luminescence studies, and reactivity.

    PubMed

    Sicilia, Violeta; Forniés, Juan; Casas, José Ma; Martín, Antonio; López, José A; Larraz, Carmen; Borja, Pilar; Ovejero, Carmen; Tordera, Daniel; Bolink, Henk

    2012-03-19

    that 1 is a very efficient and stable (3)MMLCT emitter, even in solution. The high luminescence quantum yield of its red emission, added to its neutral character and the thermal stability of 1, make it a potential compound to be incorporated as phosphorescent dopant in multilayer organic light-emitting devices (OLEDs). PMID:22360773

  5. Polymer based nanocomposites with tailorable optical properties

    NASA Astrophysics Data System (ADS)

    Colombo, Annalisa; Simonutti, Roberto

    2014-09-01

    Transparent polymers are extensively used in everyday life, from windows to computer displays, from food packaging to lenses. A possible approach for modulating their optical properties (refractive index, transparency, color and luminescence) is to change the chemical structure of the polymer, however this option is in many cases economically prohibitive. Our approach, instead, relies in the use of standard polymers with the supplement of specific nanostructured additives able to tune the final property of the material. Among others, the cases of luminescent solar concentrators based on poly(methylmethacrylate) containing luminescent quantum dots and highly transparent polymer nanocomposites with high refractive index will be presented.

  6. High cation transport polymer electrolyte

    DOEpatents

    Gerald, II, Rex E.; Rathke, Jerome W.; Klingler, Robert J.

    2007-06-05

    A solid state ion conducting electrolyte and a battery incorporating same. The electrolyte includes a polymer matrix with an alkali metal salt dissolved therein, the salt having an anion with a long or branched chain having not less than 5 carbon or silicon atoms therein. The polymer is preferably a polyether and the salt anion is preferably an alkyl or silyl moiety of from 5 to about 150 carbon/silicon atoms.

  7. Anion-controlled assembly of silver-di(aminophenyl)sulfone coordination polymers: Syntheses, crystal structures, and solid state luminescence

    SciTech Connect

    Zhang, Qi-Long; Hu, Peng; Zhao, Yi; Feng, Guang-Wei; Zhang, Yun-Qian; Zhu, Bi-Xue; Tao, Zhu

    2014-02-15

    Five silver coordination polymers, namely, ([Ag(3,3′-daps){sub 2}]·BF{sub 4}){sub n} (1), ([Ag(3,3′-daps){sub 2}]·NO{sub 3}){sub n} (2), [Ag(3,3′-daps)(CF{sub 3}SO{sub 3})]{sub n} (3), ([Ag(4,4′-daps)]·CF{sub 3}SO{sub 3}){sub n} (4), and ([Ag(4,4′-daps)]·ClO{sub 4}){sub n} (5) (3,3′-daps=di(3′-aminodiphenyl)sulfone, and 4,4′-daps=di(4′-aminodiphenyl)sulfone) have been synthesized and structural characterized by elemental analyses, IR spectra, powder X-ray diffraction (PXRD) and single-crystal X-ray diffraction analyses. Complex 1 displays a 1D ladder-like chain with four-connected Ag ions and bridged 3,3′-daps. Complex 2 shows other 1D ladder chain modified by tentacles. Complex 3 is a 2D layer structure with both Ag ions and 3,3′-daps are 3-connected nodes. Complex 4 is another 1D ladder chain with three-connected Ag ions and 4,4′-daps. Complex 5 shows a 2D 4{sup 4}-sql net with Ag ions and 4,4′-daps as 4-connected nodes. Moreover, their solid state luminescence and thermal stabilities also have been investigated. - Graphical abstract: Pictogram: Synthetic procedures of the five anion controlled silver coordination polymers. We reported the synthetic procedures, structure, and luminescence property of the five anion controlled silver coordination polymers based on two novel di(aminophenyl)sulfone V-shaped ligands. Display Omitted - Highlights: • Five new silver coordination polymers were synthesized and characterized. • Two novel designed V-shaped di(aminophenyl)sulfone ligands were first introduced to coordination chemistry. • Anions play important roles in determining the five silver coordination polymers. • The structural diversity and photoluminescence property were also discussed.

  8. Rethinking Sensitized Luminescence in Lanthanide Coordination Polymers and MOFs: Band Sensitization and Water Enhanced Eu Luminescence in [Ln(C15H9O5)3(H2O)3]n (Ln = Eu, Tb).

    PubMed

    Einkauf, Jeffrey D; Kelley, Tanya T; Chan, Benny C; de Lill, Daniel T

    2016-08-15

    A coordination polymer [Ln(C15H9O9)3(H2O)3]n (1-Ln = Eu(III), Tb(III)) assembled from benzophenonedicarboxylate was synthesized and characterized. The organic component is shown to sensitize lanthanide-based emission in both compounds, with quantum yields of 36% (Eu) and 6% (Tb). Luminescence of lanthanide coordination polymers is currently described from a molecular approach. This methodology fails to explain the luminescence of this system. It was found that the band structure of the organic component rather than the molecular triplet state was able to explain the observed luminescence. Deuterated (Ln(C15H9O9)3(D2O)3) and dehydrated (Ln(C15H9O9)3) analogues were also studied. When bound H2O was replaced by D2O, lifetime and emission increased as expected. Upon dehydration, lifetimes increased again, but emission of 1-Eu unexpectedly decreased. This reduction is reasoned through an unprecedented enhancement effect of the compound's luminescence by the OH/OD oscillators in the organic-to-Eu(III) energy transfer process. PMID:27472192

  9. Syntheses, structures and luminescent properties of a series of 3D lanthanide coordination polymers with tripodal semirigid ligand

    SciTech Connect

    Qin Junsheng; Du Dongying; Chen Lei; Sun Xiuyun; Lan Yaqian; Su Zhongmin

    2011-02-15

    Reactions of the tripodal bridging ligand 5-(4-carboxy-phenoxy)-isophthalic acid (abbreviated as H{sub 3}cpia) with lanthanide salts lead to the formation of a family of different coordination polymers, that is, [Ln(cpia)(H{sub 2}O){sub 2}]{sub n}.nH{sub 2}O (Ln=Ce (1), Pr (2), Nd (3), Sm (4), Eu (5), Gd (6), Dy (7), Er (8), Tm (9) and Y (10)) in the presence of formic acid or diethylamine, which are characterized by elemental analysis, IR spectrum, thermogravimetric analysis (TGA), XRPD spectrum and single-crystal X-ray diffraction. Compounds 1-10 are isostructural and exhibit three-dimensional microporous frameworks. Furthermore, the photoluminescent properties of 4, 5 and 7 have been studied in detail. -- Graphical abstract: Reactions of the tripodal bridging ligand (H{sub 3}cpia) with lanthanide ions lead to the formation of a series of coordination polymers in the presence of formic acid or diethylamine. Display Omitted Research Highlights: {yields} Ten new lanthanides-based coordination polymers (1-10) have been synthesized. {yields} 1-10 exhibit 3D (4,8)-connected fluorite topology networks with 1D channel parallel to the b-axis. {yields} Compounds 4, 5 and 7 exhibit characteristic luminescence of Sm{sup 3+}, Eu{sup 3+} and Dy{sup 3+} ions, respectively.

  10. Mono/bimetallic water-stable lanthanide coordination polymers as luminescent probes for detecting cations, anions and organic solvent molecules.

    PubMed

    Wang, Huarui; Qin, Jianhua; Huang, Chao; Han, Yanbing; Xu, Wenjuan; Hou, Hongwei

    2016-08-01

    Eleven water-stable isostructural mono/bimetallic lanthanide coordination polymers (Ln-CPs) {[EuxTb1-x (HL)(H2O)3]·H2O}n (x = 1.0 (1), 0.9 (3), 0.8 (4), 0.7 (5), 0.6 (6), 0.4 (7), 0.3 (8), 0.2 (9), 0.1 (10), 0.05 (11), 0 (2), H4L = 5,5'-(1H-2,3,5-triazole-1,4-diyl)diisophthalic acid) with uncoordinated Lewis basic triazole sites within the pores were prepared. The Ln-CPs represented by 1 showed a rapid and drastic emission quenching induced by external Fe(3+) and Cr(3+) cations and CrO4(2-) and CO3(2-) anions in aqueous solution. In addition, because of the comparable emission intensities of Eu(3+) and Tb(3+) ions, bimetallic CP 8 can be used as a ratiometric luminescent sensor for organic solvent molecules. Moreover, the luminescent color of the 8 sensor in pyridine and in other guest solvents undergoes obvious changes that can be clearly distinguished by the naked eye. PMID:27443408

  11. Two-photon excited quantum dots with compact surface coatings of polymer ligands used as an upconversion luminescent probe for dopamine detection in biological fluids.

    PubMed

    Jin, Hui; Gui, Rijun; Wang, Zonghua; Zhang, Feifei; Xia, Jianfei; Yang, Min; Bi, Sai; Xia, Yanzhi

    2015-03-21

    Water-soluble multidentate polymer coated CdTe quantum dots (QDs) were prepared via a stepwise addition of raw materials in a one-pot aqueous solution under ambient conditions. Just by adjusting the compositions of raw materials, different sized CdTe QDs were achieved within a short time. The as-prepared QDs showed compact surface coating (1.6-1.8 nm) of polymer ligands and photoluminescence (PL) emitted at 533-567 nm, as well as high colloidal/photo-stability and quantum yields (58-67%). Moreover, these QDs exhibited significant upconversion luminescence (UCL) upon excitation using an 800 nm femtosecond laser. Experimental results confirm that the UCL was ascribed to the two-photon assisted process via a virtual energy state. Then, the two-photon excited QDs were further developed as a novel UCL probe of dopamine (DA) due to self-assembled binding of DA molecules with QDs via non-covalent bonding. As a receptor, the DA attached onto the QD surface induced an electron transfer from QDs to DA, triggering UCL quenching of QDs. This UCL probe of DA presented a low limit of detection (ca. 5.4 nM), and high selectivity and sensitivity in the presence of potential interferences. In particular, it was favorably applied to the detection of DA in biological fluids, with quantitative recoveries (96.0-102.6%). PMID:25684191

  12. Radiation effects on high performance polymers

    NASA Technical Reports Server (NTRS)

    Orwoll, R. A.

    1986-01-01

    Polymer matrix materials are candidates for use in large space antennas and space platforms that may be deployed in geosynchronous orbit 22,500 miles above the Earth. A principal concern is the long term effects of an environment that is hostile to organic polymers, including high energy electromagnetic radiation, bombardment by charged particles, and large abrupt changes in temperature. Two polyarylene ethers which might be utilized as models for polymers in space applications were subjected to dosages of 70 keV electrons up to 3.4 x 10 to the 10th power rad. The irradiated films were then examined to determine the effects of the high-energy electrons.

  13. The crystal structure, luminescence and nitrobenzene-sensing properties of a two-dimensional Mn(II) coordination polymer based on 2,6-bis(imidazol-1-yl)pyridine.

    PubMed

    Wang, Yin-Lin; Long, Ling-Liang; Zhang, Jin-Fang

    2015-06-01

    A two-dimensional Mn(II) coordination polymer (CP), poly[bis[μ2-2,6-bis(imidazol-1-yl)pyridine-κ(2)N(3):N(3')]bis(thiocyanato-κN)manganese] [Mn(NCS)2(C11H9N5)2]n, (I), has been obtained by the self-assembly reaction of Mn(ClO4)2·6H2O, NH4SCN and bent 2,6-bis(imidazol-1-yl)pyridine (2,6-bip). CP (I) was characterized by FT-IR spectroscopy, elemental analysis and single-crystal X-ray diffraction. The crystal structure features a unique two-dimensional (4,4) network with one-dimensional channels. The luminescence and nitrobenzene-sensing properties were explored in a DMF suspension, revealing that CP (I) shows a strong luminescence emission and is highly sensitive for nitrobenzene detection. PMID:26044322

  14. On the high conductivity of nonconjugated polymers

    SciTech Connect

    Lachinov, A. N. Kornilov, V. M.; Zagurenko, T. G.; Zherebov, A. Yu.

    2006-04-15

    The mechanism of charge transfer in a metal-electroactive polymer-metal structure has been experimentally studied near the threshold of the uniaxial-pressure-induced transition into a high-conductivity state in the polymer. The dynamics of the I-V curve is investigated as a function of the applied pressure. The data obtained are analyzed in terms of the model of injection currents using the concepts of possible scanning of a quasi-Fermi level near an injection level. Our estimates suggest that a narrow band made of deep trap states located near the Fermi level forms in the polymer film in the pretransition pressure range. In the immediate vicinity of the transition range, a narrow band of coherent charge transfer appears from these states; this band can be responsible for the high metal-type conductivity of thin polymer films, which has been repeatedly observed by many researchers.

  15. Material and Optical Design Rules for High Performance Luminescent Solar Concentrators

    NASA Astrophysics Data System (ADS)

    Bronstein, Noah Dylan

    This dissertation will highlight a path to achieve high photovoltaic conversion efficiency in luminescent solar concentrators, devices which absorb sunlight with a luminescent dye and then re-emit it into a waveguide where it is ultimately collected by a photovoltaic cell. Luminescent concentrators have been studied for more than three decades as potential low-cost but not high efficiency photovoltaics. Astute application of the blackbody radiation law indicates that photonic design is necessary to achieve high efficiency: a reflective filter must be used to trap luminescence at all angles while allowing higher energy photons to pass through. In addition, recent advances in the synthesis of colloidal nanomaterials have created the possibility for lumophores with broad absorption spectra, narrow-bandwidth emission, high luminescence quantum yield, tunable Stokes shifts and tunable Stokes ratios. Together, these factors allow luminescent solar concentrators to achieve the optical characteristics necessary for high efficiency. We have fabricated and tested the first generation of these devices. Our experiments demonstrate that the application of carefully matched photonic mirrors and luminescent quantum dots can allow luminescent concentration factors to reach record values while maintaining high photon collection efficiency. Finally, the photonic mirror dramatically mitigates the negative impact of scattering in the waveguide, allowing efficient photon collection over distances much longer than the scattering length of the waveguide. After demonstrating the possibility for high performance, we theoretically explore the efficacy of luminescent concentrators with dielectric reflectors as the high-bandgap top-junctions in two-junction devices. Simple thermodynamic calculations indicate that this approach can be nearly as good as a traditional vertically stacked tandem. The major barriers to such a device are the optical design of narrow-bandwidth, angle

  16. Polymer blends as high explosive binders

    SciTech Connect

    Hoffman, D.M.; Caley, L.E.

    1984-10-05

    One approach to high-density, high-modulus binders for explosives is to blend low-density, high-modulus polymers with high-density, low-modulus polymers. Improved properties, which miscible pairs theoretically should have, are discussed. Two attempts to achieve miscibility between a high-density fluoropolymer (Kel-F 800) and high-modulus thermoplastics (Lucite 130 and Phenoxy PKHJ) were unsuccessful. These blends are immiscible and their physical properties are additive or not significantly enhanced. Anelastic properties of the blends indicate phase separation by the presence of two glass transitions, one associated with each phase. Unfortunately, neither of these pairs has merit as an improved plastic-bonded explosive binder. However, a compatible (miscible) pair would be an improved binder if the appropriate polymer pair could be found.

  17. Proceedings of the third CECRI research conference on luminescence

    SciTech Connect

    Rao, R.P.

    1992-01-01

    This book reports on luminescence phenomena. Some important papers included in this part are theory of multiple trapping rate, radiationless processes, upconversion processes, lyo-and pyroelectric luminescence, photo and laser stimulated luminescence, linear and nonlinear TL effects, deep centers in diamonds, localized states in mixed crystals and fluorescence in polymers. This book also covers a side spectrum of phosphor materials such as alkaline earth sulphides, sulphates, fluorides and borates, zinc and cadmium sulphides, zinc and aluminum oxides, alkali halides, semiconductors, high T{sub c} superconductors, pigments and polymers.

  18. High temperature polymer concrete compositions

    DOEpatents

    Fontana, Jack J.; Reams, Walter

    1985-01-01

    This invention is concerned with a polymer concrete composition, which is a two-component composition useful with many bases including metal. Component A, the aggregate composition, is broadly composed of silica, silica flour, portland cement, and acrylamide, whereas Component B, which is primarily vinyl and acrylyl reactive monomers, is a liquid system. A preferred formulation emphasizing the major necessary components is as follows: ______________________________________ Component A: Silica sand 60-77 wt. % Silica flour 5-10 wt. % Portland cement 15-25 wt. % Acrylamide 1-5 wt. % Component B: Styrene 50-60 wt. % Trimethylolpropane 35-40 wt. % trimethacrylate ______________________________________ and necessary initiators, accelerators, and surfactants.

  19. Syntheses, crystal structure, and luminescence properties of three new Cd(II) polymers based on different conformational carboxylates

    NASA Astrophysics Data System (ADS)

    Liu, Jian-Qiang; Jia, Zhen-Bin; Wang, Yao-Yu

    2011-02-01

    Three new coordination polymers, namely, {[Cd 3(L 1) 2(IP) 2(H 2O) 4]} n ( 1), {[Cd 2(L 2) 2(IP) 2]·(CH 3OH)(DMF)} n ( 2) and [Cd(L 3)(IP)] n ( 3) (H 3L 1 = benzene-1,2,4-tricarboxylic acid, H 2L 2 = 2,2-bis(4-carboxyphenyl)hexafluoropropane, H 2L 3 = 1,3-phenylenediacetic acid and IP = 1H-imidazo[4,5-f][1,10]-phenanthroline), were prepared via self-assembly of pharmaceutical agent IP with cadmium sulfate in the presence of the different backbones of carboxylate linkers under mild conditions. All the polymers possess 2D structural motifs. The rigid tricarboxylate ligand links the metal centers to form a tetranuclear core in 1. In 2, the 2D network with trinuclear cores is further extended into 3D supramolecular arrays through aromatic stacking interactions. Interestingly, IP ligand acts in a tridentate mode via the two N atoms of pyridyl rings and the third N atom of imidazole ring and connects metal atoms into 1D zigzag chain in 3. The structural analysis reveals that the backbones of carboxylates have critical effect on the construction of the complexes. Solid-state luminescent spectra of the Cd(II) complexes indicate intense fluorescent emissions.

  20. Multicolor Luminescence from Conjugates of Genetically Encoded Elastin-like Polymers and Terpyridine-Lanthanides

    DOE PAGESBeta

    Ghosh, Koushik; Balog, Eva Rose M.; Kahn, Jennifer L.; Shepherd, Douglas P.; Martinez, Jennifer S.; Rocha, Reginaldo C.

    2015-08-20

    Functional hybrid materials with optically active metal-ligand moieties embedded within a polymer matrix have a great potential in (bio)materials science, including applications in light-emitting diode devices. Here, we report a simple strategy to incorporate terpyridine derivatives into the side chains of elastin-like polymers (ELPs). The further binding of trivalent lanthanide ions with the terpyridine ligands generated an array of photoluminescence ranging from the visible to the near-infrared regions. Lastly, as thin films, these ELP-based optical materials also exhibited distinct morphologies that depend upon the temperature of the aqueous solutions from which the hybrid polymers were spin coated or drop cast.

  1. High efficiency green-luminescent LaPO 4:Ce,Tb hierarchical nanostructures: Synthesis, characterization, and luminescence properties

    NASA Astrophysics Data System (ADS)

    Fu, Zhenxiao; Bu, Wenbo

    2008-08-01

    High efficiency green-luminescent LaPO 4:Ce,Tb hierarchical nanostructures with uniform spindle shape have been successfully constructed by a simple Pluronic P123-assisted hydrothermal approach via self-assembling from single-crystalline nanowires. Their morphologies and structures were examined by scanning and transmission electron microscopy. The resulting uniform spindle-shaped microstructures are composed of several tens of aligned single-crystalline nanowires. The surfactant Pluronic P123 was found to play a crucial role in achieving uniform morphology of the final product as compared with the same material but synthesized without the surfactant Pluronic P123. These LaPO 4:Ce,Tb spindle-shaped microstructures show efficient photoluminescence which is associated with its surface smoothness, high crystallization and uniform morphologies of the micro-architectures.

  2. Bright luminescence in lanthanide coordination polymers with tetrafluoroterephthalate as a bridging ligand.

    PubMed

    Sobieray, Miriam; Gode, Jens; Seidel, Christiane; Poß, Marieke; Feldmann, Claus; Ruschewitz, Uwe

    2015-04-01

    Ten new coordination polymers of the general compositions ∞²[Ln(III)(tfBDC)(NO3)(DMF)2]·DMF with Ln(III) = Eu(3+) (1), Gd(3+) (2), Tb(3+) (3), Ho(3+) (4), Tm(3+) (5), ∞²[Ln(III)(tfBDC)(CH3COO)(FA)3]·3FA with Ln(III) = Sm(3+) (6), Eu(3+) (7) and ∞²[Ln(III)(tfBDC)(NO3)(DMSO)2] with Ln(III) = Ho(3+) (8), Er(3+) (9) and Tm(3+) (10) were synthesized and structurally characterized by X-ray single crystal diffraction (tfBDC(2-) = 2,3,5,6-tetrafluoroterephthalate, DMF = N,N'-dimethylformamide, FA = formamide, DMSO = dimethyl sulfoxide). 1-5 crystallize in the monoclinic space group C2/c with Z = 8, 6 and 7 in P1̄ with Z = 2 and 8-10 in Pbca with Z = 8. All crystal structures contain binuclear lanthanide nodes that are connected by 2,3,5,6-tetrafluoroterephthalates (tfBDC(2-)) to form two-dimensional polymeric structural units. Despite this common structural feature the coordination within these binuclear units is quite different in detail, e.g. CN = 9 for 1-7 and CN = 8 for 8-10. The emission spectra of the europium (1, 7) and terbium (3) compounds reveal bright red and green emission in the visible region. The resulting high quantum yields of 53% (1) and 67% (3) at room temperature show that the replacement of organic ligands with C-H groups by perfluorinated ligands leads to compounds with intense emission, as vibrational quenching is reduced. On the other hand, the influence of the coordinating solvent and additional ligands cannot be neglected, as the replacement of DMF by FA and NO3(-) by CH3COO(-) in 7 leads to a reduced quantum yield of only 10%. Thermoanalytical investigations show that all compounds are stable up to 100-150 °C, before a stepwise release of solvent molecules starts followed by a decomposition of the coordination polymer. PMID:25740408

  3. Lanthanide coordination polymers based on multi-donor ligand containing pyridine and phthalate moieties: Structures, luminescence and magnetic properties

    SciTech Connect

    Feng, Xun; Liu, Lang; Wang, Li-Ya; Song, Hong-Liang; Qiang Shi, Zhi; Wu, Xu-Hong; Ng, Seik-Weng

    2013-10-15

    A new family of five lanthanide-organic coordination polymers incorporating multi-functional N-hetrocyclic dicarboxylate ligand, namely, [Ln{sub 2}(Hdpp){sub 2}(dpp){sub 2}]{sub n}Ln=Pr(1), Eu(2), Gd(3), Dy(4), Er(5) (H{sub 2}dpp=1-(3, 4-dicarboxyphenyl) pyridin-4-ol) have been fabricated successfully through solvothermal reaction of 1-(3,4-dicarboxyphenyl)-4-hydroxypyridin-1-ium chloride with trivalent lanthanide salts, and have been characterized systematically. The complexes 1–5 are isomorphous and isostructural. They all feature three dimensional (3D) frameworks based on the interconnection of 1D double chains composed of the binuclear moiety [Ln{sub 2}(Hdpp){sub 2}]{sup 4+} basic carboxylate as secondary building unit (SBU). The results of magnetic analysis shows the same bridging fashion of carboxylic group in this case results in the different magnetic properties occurring within lanthanide polymers. Moreover, the Eu(III) and Dy(III) complexes display characteristic luminescence emission in the visible regions. - Graphical abstract: A new family of lanthanide-organic frameworks incorporating multi-donor twisted ligand has been fabricated successfully, and has been characterized systematically. The complexes 1–5 are isostructural, and all feather three dimensional (3D) frameworks based on the interconnection of 1D double stride chains composed of the binuclear moiety [Ln{sub 2}(Hdpp){sub 2}]{sup 2+} basic carboxylate as secondary building unit (SBU). Display Omitted - Highlights: • New family of lanthanide–organic coordination polymers incorporating multifunctional N-hetrocyclic dicarboxylate ligand has been fabricated. • They have been characterized systematically. • They all feather three dimensional frameworks based on the binuclear moiety of [Ln{sub 2}(Hdpp){sub 2}]{sup 2+}. • The Eu(III) and Dy(III) analogues exhibit intense photoluminescence.

  4. Uranyl sensitization of samarium (III) luminescence in a two-dimensional coordination polymer

    SciTech Connect

    Knope, Karah E.; de Lill, Daniel T.; Rowland, Clare E.; Cantos, Paula M.; de Bettencourt-Dias, Ana; Cahill, Christopher L.

    2012-01-02

    Heterometallic carboxyphosphonates UO₂2+/Ln3+ have been prepared from the hydrothermal reaction of uranyl nitrate, lanthanide nitrate (Ln = Sm, Tb, Er, Yb), and phosphonoacetic acid (H₃PPA). Compound 1, (UO₂)₂(PPA)(HPPA)₂Sm(H₂O)·2H₂O (1) adopts a two-dimensional structure in which the UO₂2+ metal ions bind exclusively to the phosphonate moiety, whereas the Ln3+ ions are coordinated by both phosphonate and carboxylate functionalities. Luminescence studies of 1 show very bright visible and near-IR samarium(III)-centered emission upon direct excitation of the uranyl moiety. The Sm3+ emissive state exhibits a double-exponential decay with lifetimes of 67.2 ± 6.5 and 9.0 ± 1.3 μs as measured at 594 nm, after excitation at both 365 and 420 nm. No emission is observed in the region typical of the uranyl cation, indicating that all energy is either transferred to the Sm3+ center or lost to nonradiative processes. Herein we report the synthesis, crystal structure, and luminescent behavior of 1, as well as those of the isostructural terbium, erbium, and ytterbium analogues.

  5. High-Temperature Thermometer Using Cr-Doped GdAlO3 Broadband Luminescence

    NASA Technical Reports Server (NTRS)

    Eldridge, Jeffrey; Chambers, Matthew

    2011-01-01

    A new concept has been developed for a high-temperature luminescence-based optical thermometer that both shows the desired temperature sensitivity in the upper temperature range of present state-of-the-art luminescence thermometers (above 1,300 C), while maintaining substantial stronger luminescence signal intensity that will allow these optical thermometers to operate in the presence of the high thermal background radiation typical of industrial applications. This objective is attained by using a Cr-doped GdAlO3 (Cr:GdAlO3) sensor with an orthorhombic perovskite structure, resulting in broadband luminescence that remains strong at high temperature due to the favorable electron energy level spacing of Cr:GdAlO3. The Cr:GdAlO3 temperature (and pressure) sensor can be incorporated into, or applied onto, a component s surface when a non-contact surface temperature measurement is desired, or alternatively, the temperature sensor can be attached to the end of a fiber-optic probe that can then be positioned at the location where the temperature measurement is desired. In the case of the fiber-optic probe, both the pulsed excitation and the luminescence emission travel through the fiber-optic light guide. In either case, a pulsed light source provides excitation of the luminescence, and the broadband luminescence emission is collected. Real-time temperature measurements are obtain ed using a least-squares fitting algorithm that determines the luminescence decay time, which has a known temperature dependence established by calibration. Due to the broad absorption and emission bands for Cr:GdAlO3, there is considerable flexibility in the choice of excitation wavelength and emission wavelength detection bands. The strategic choice of the GdAlO3 host is based on its high crystal field, phase stability, and distorted symmetry at the Cr3+ occupation sites. The use of the broadband emission for temperature sensing at high temperatures is a key feature of the invention and is

  6. Effective Detection of Mycotoxins by a Highly Luminescent Metal-Organic Framework.

    PubMed

    Hu, Zhichao; Lustig, William P; Zhang, Jingming; Zheng, Chong; Wang, Hao; Teat, Simon J; Gong, Qihan; Rudd, Nathan D; Li, Jing

    2015-12-30

    We designed and synthesized a new luminescent metal-organic framework (LMOF). LMOF-241 is highly porous and emits strong blue light with high efficiency. We demonstrate for the first time that very fast and extremely sensitive optical detection can be achieved, making use of the fluorescence quenching of an LMOF material. The compound is responsive to Aflatoxin B1 at parts per billion level, which makes it the best performing luminescence-based chemical sensor to date. We studied the electronic properties of LMOF-241 and selected mycotoxins, as well as the extent of mycotoxin-LMOF interactions, employing theoretical methods. Possible electron and energy transfer mechanisms are discussed. PMID:26654703

  7. Detection of surface impurity phases in high T.sub.C superconductors using thermally stimulated luminescence

    DOEpatents

    Cooke, D. Wayne; Jahan, Muhammad S.

    1989-01-01

    Detection of surface impurity phases in high-temperature superconducting materials. Thermally stimulated luminescence has been found to occur in insulating impurity phases which commonly exist in high-temperature superconducting materials. The present invention is sensitive to impurity phases occurring at a level of less than 1% with a probe depth of about 1 .mu.m which is the region of interest for many superconductivity applications. Spectroscopic and spatial resolution of the emitted light from a sample permits identification and location of the impurity species. Absence of luminescence, and thus of insulating phases, can be correlated with low values of rf surface resistance.

  8. Electrochemical deposition of patterning and highly luminescent organic films for light emitting diodes

    NASA Astrophysics Data System (ADS)

    Li, Mao; Tang, Shi; Lu, Dan; Shen, Fangzhong; Liu, Meirong; Wang, Huan; Lu, Ping; Hanif, Muddasir; Ma, Yuguang

    2007-08-01

    This paper describes a simple electrochemical deposition (ED) technique to prepare luminescent and patterned films for light-emitting devices (LEDs). The luminescent films are deposited directly on the patterned ITO (indium tin oxide) electrodes through an oxidation coupling reaction of an electroactive and luminescent precursor. The ED films deposited on the ITO strips (width of 200 µm) exhibit smooth surface morphology (roughness of morphology surface of 3.1 nm), small roughness in electrode edge of 1-2 µm and high fluorescence quantum efficiency (>60%). The LEDs with structure ITO/ED film/Ba/Al show pure blue emission (CIE coordinates of (0.16, 0.07)), high brightness of 3080 cd m-2 and the maximum external quantum efficiency of 0.60%.

  9. Highly selective luminescent nanostructures for mitochondrial imaging and targeting.

    PubMed

    Fanizza, E; Iacobazzi, R M; Laquintana, V; Valente, G; Caliandro, G; Striccoli, M; Agostiano, A; Cutrignelli, A; Lopedota, A; Curri, M L; Franco, M; Depalo, N; Denora, N

    2016-02-14

    Here a luminescent hybrid nanostructure based on functionalized quantum dots (QDs) is used as a fluorescent imaging agent able to target selectively mitochondria thanks to the molecular recognition of the translocator protein (TSPO). The selective targeting of such an 18 kDa protein mainly located in the outer mitochondrial membrane and overexpressed in several pathological states including neurodegenerative diseases and cancers may provide valuable information for the early diagnosis and therapy of human disorders. In particular, the rational design of amino functionalized luminescent silica coated QD nanoparticles (QD@SiO2 NPs) provides a versatile nanoplatform to anchor a potent and selective TSPO ligand, characterized by a 2-phenyl-imidazo[1,2-a]pyridine acetamide structure along with a derivatizable carboxylic end group, useful to conjugate the TSPO ligand and achieve TSPO-QD@SiO2 NPs by means of a covalent amide bond. The colloidal stability and optical properties of the proposed nanomaterials are comprehensively investigated and their potential as mitochondrial imaging agents is fully assessed. Sub-cellular fractionation, together with confocal laser scanning fluorescence microscopy and co-localization analysis of targeted TSPO-QD@SiO2 NPs in C6 glioma cells overexpressing the TSPO, proves the great potential of these multifunctional nanosystems as in vitro selective mitochondrial imaging agents. PMID:26763470

  10. Strong Circularly Polarized Luminescence from Highly Emissive Terbium Complexes in Aqueous Solution

    SciTech Connect

    Samuel, Amanda; Lunkley, Jamie; Muller, Gilles; Raymond, Kenneth

    2010-03-15

    Two luminescent terbium(III) complexes have been prepared from chiral ligands containing 2-hydroxyisophthalamide (IAM) antenna chromophores and their non-polarized and circularly-polarized luminescence properties have been studied. These tetradentate ligands, which form 2:1 ligand/Tb{sup III} complexes, utilize diaminocyclohexane (cyLI) and diphenylethylenediamine (dpenLI) backbones, which we reasoned would impart conformational rigidity and result in Tb{sup III} complexes that display both large luminescence quantum yield ({phi}) values and strong circularly polarized luminescence (CPL) activities. Both Tb{sup III} complexes are highly emissive, with {phi} values of 0.32 (dpenLI-Tb) and 0.60 (cyLI-Tb). Luminescence lifetime measurements in H{sub 2}O and D{sub 2}O indicate that while cyLI-Tb exists as a single species in solution, dpenLI-Tb exists as two species: a monohydrate complex with one H{sub 2}O molecule directly bound to the Tb{sup III} ion and a complex with no water molecules in the inner coordination sphere. Both cyLI-Tb and dpenLI-Tb display increased CPL activity compared to previously reported Tb{sup III} complexes made with chiral IAM ligands. The CPL measurements also provide additional confirmation of the presence of a single emissive species in solution in the case of cyLI-Tb, and multiple emissive species in the case of dpenLI-Tb.

  11. Immunochromatographic assay for ultrasensitive detection of aflatoxin B₁ in maize by highly luminescent quantum dot beads.

    PubMed

    Ren, Meiling; Xu, Hengyi; Huang, Xiaolin; Kuang, Min; Xiong, Yonghua; Xu, Hong; Xu, Yang; Chen, Hongyu; Wang, Andrew

    2014-08-27

    Highly luminescent quantum dot beads (QBs) were synthesized by encapsulating CdSe/ZnS and used for the first time as immunochromatographic assay (ICA) signal amplification probe for ultrasensitive detection of aflatoxin B1 (AFB1) in maize. The challenges to using high brightness QBs as probes for ICA are smooth flow of QBs and nonspecific binding on nitrocellulose (NC) membrane, which are overcome by unique polymer encapsulation of quantum dots (QDs) and surface blocking method. Under optimal conditions, the QB-based ICA (QB-ICA) sensor exhibited dynamic linear detection of AFB1 in maize extract from 5 to 60 pg mL(-1), with a median inhibitory concentration (IC50) of 13.87 ± 0.16 pg mL(-1), that is significantly (39-fold) lower than those of the QD as a signal probe (IC50 = 0.54 ± 0.06 ng mL(-1)). The limit of detection (LOD) for AFB1 using QB-ICA sensor was 0.42 pg mL(-1) in maize extract, which is approximately 2 orders of magnitude better than those of previously reported gold nanoparticle based immunochromatographic assay (AuNP-ICA) and is even comparable with or better than the conventional enzyme-linked immunosorbent assay (ELISA) method. The performance and practicability of our QB-ICA sensor were validated with a commercial ELISA kit and further confirmed with liquid chromatography tandem mass spectrometry (LC-MS/MS). Given its efficient signal amplification performance, the proposed QB-ICA offers great potential for rapid, sensitive, and cost-effective quantitative detection of analytes in food safety monitoring. PMID:25109633

  12. Enhanced radiation detectors using luminescent materials

    DOEpatents

    Vardeny, Zeev V.; Jeglinski, Stefan A.; Lane, Paul A.

    2001-01-01

    A radiation detecting device comprising a radiation sensing element, and a layer of luminescent material to expand the range of wavelengths over which the sensing element can efficiently detect radiation. The luminescent material being selected to absorb radiation at selected wavelengths, causing the luminescent material to luminesce, and the luminescent radiation being detected by the sensing element. Radiation sensing elements include photodiodes (singly and in arrays), CCD arrays, IR detectors and photomultiplier tubes. Luminescent materials include polymers, oligomers, copolymers and porphyrines, Luminescent layers include thin films, thicker layers, and liquid polymers.

  13. Highly selective luminescent nanostructures for mitochondrial imaging and targeting

    NASA Astrophysics Data System (ADS)

    Fanizza, E.; Iacobazzi, R. M.; Laquintana, V.; Valente, G.; Caliandro, G.; Striccoli, M.; Agostiano, A.; Cutrignelli, A.; Lopedota, A.; Curri, M. L.; Franco, M.; Depalo, N.; Denora, N.

    2016-02-01

    Here a luminescent hybrid nanostructure based on functionalized quantum dots (QDs) is used as a fluorescent imaging agent able to target selectively mitochondria thanks to the molecular recognition of the translocator protein (TSPO). The selective targeting of such an 18 kDa protein mainly located in the outer mitochondrial membrane and overexpressed in several pathological states including neurodegenerative diseases and cancers may provide valuable information for the early diagnosis and therapy of human disorders. In particular, the rational design of amino functionalized luminescent silica coated QD nanoparticles (QD@SiO2 NPs) provides a versatile nanoplatform to anchor a potent and selective TSPO ligand, characterized by a 2-phenyl-imidazo[1,2-a]pyridine acetamide structure along with a derivatizable carboxylic end group, useful to conjugate the TSPO ligand and achieve TSPO-QD@SiO2 NPs by means of a covalent amide bond. The colloidal stability and optical properties of the proposed nanomaterials are comprehensively investigated and their potential as mitochondrial imaging agents is fully assessed. Sub-cellular fractionation, together with confocal laser scanning fluorescence microscopy and co-localization analysis of targeted TSPO-QD@SiO2 NPs in C6 glioma cells overexpressing the TSPO, proves the great potential of these multifunctional nanosystems as in vitro selective mitochondrial imaging agents.Here a luminescent hybrid nanostructure based on functionalized quantum dots (QDs) is used as a fluorescent imaging agent able to target selectively mitochondria thanks to the molecular recognition of the translocator protein (TSPO). The selective targeting of such an 18 kDa protein mainly located in the outer mitochondrial membrane and overexpressed in several pathological states including neurodegenerative diseases and cancers may provide valuable information for the early diagnosis and therapy of human disorders. In particular, the rational design of amino

  14. Strongly luminescent, highly ionic europium in a lanthanum diphenylphosphinate matrix

    NASA Astrophysics Data System (ADS)

    Abreu, Edson M.; Francisco, Cristina S.; Klein, Stanlei I.; Stucchi, Elizabeth B.

    2013-01-01

    A series of insoluble, chemically inert and thermally stable compounds La1-xEux(DPP)3 (x = 0.50, 0.20, 0.10, and 0.050; DPP = diphenylphosphinate) was synthesized and characterized by elemental and thermogravimetric analysis, FT Infrared spectroscopy and X-ray powder diffraction. Luminescence spectroscopy at both 77 and 298 K showed changes in the intensity of the hypersensitive transition 5D0 → 7F2 of Eu3+ which are dependent of the excitation wavelength, suggesting that the europium occupies two different sites in the compounds. The large quantum efficiency and quantum yield, as well as the long radiative lifetime of the 5D0 Eu3+ level of the series of compounds, which are desirable qualities for light-conversion molecular devices, are discussed in terms of the interactions and the energy transfer process between the ligands and the metal ion.

  15. High Strain Rate Rheology of Polymer Melts

    NASA Astrophysics Data System (ADS)

    Kelly, Adrian; Gough, Tim; Whiteside, Ben; Coates, Phil D.

    2009-07-01

    A modified servo electric injection moulding machine has been used in air-shot mode with capillary dies fitted at the nozzle to examine the rheology of a number of commercial polymers at wall shear strain rates of up to 107 s-1. Shear and extensional flow properties were obtained through the use of long and orifice (close to zero land length) dies of the same diameter. A range of polyethylene, polypropylene and polystyrene melts have been characterized; good agreement was found between the three techniques used in the ranges where strain rates overlapped. Shear viscosity of the polymers studied was found to exhibit a plateau above approximately 1×106 s-1. A relationship between the measured high strain rate rheological behaviour and molecular structure was noted, with polymers containing larger side groups reaching the rate independent plateau at lower strain rates than those with simpler structures.

  16. A highly sensitive near-infrared luminescent metal-organic framework thermometer in the physiological range.

    PubMed

    Zhao, Dian; Zhang, Jun; Yue, Dan; Lian, Xiusheng; Cui, Yuanjing; Yang, Yu; Qian, Guodong

    2016-07-01

    A near-infrared luminescent metal-organic framework Nd0.866Yb0.134BTB was developed as a self-calibrated thermometer in the physiological range. Its features include high sensitivity and resolution, and good biocompatibility, making such a material useful for biomedical applications. PMID:27284589

  17. Synthesis, crystal structures, luminescence and catalytic properties of two d¹⁰ metal coordination polymers constructed from mixed ligands.

    PubMed

    Wang, Xiao-xiao; Zhang, Ming-xi; Yu, Baoyi; Van Hecke, Kristof; Cui, Guang-hua

    2015-03-15

    Two new coordination polymers [Cd(bmb)(hmph)]n (1), {[Ag(bmb)]·H2btc}n (2) (bmb=1,4-bis(2-methylbenzimidazol-1-ylmethyl)benzene, H2hmph=homophthalic acid, H3btc=1,3,5-benzenetetracarboxylic acid) were synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction methods, IR spectroscopy, TGA, XRPD and elemental analysis. Complex 1 features a 3D threefold interpenetrating dia array with a 4-connected 6(6) topology. Complex 2 shows a 1D helix chain structure connected by L1 ligands, which is finally extended into a rarely 2D 4L2 supramolecular network via C-H⋯O hydrogen bond interactions. In addition, the luminescence and catalytic properties of the two complexes for the degradation of the methyl orange azo dye in a Fenton-like process were presented. The degradation efficiency of the methyl orange azo dye for 1 and 2 are 56% and 96%, respectively. PMID:25576941

  18. Two new pyridine-2,3-dicarboxylate coordination polymers prepared from zerovalent metal precursor: Syntheses, luminescent and magnetic properties

    NASA Astrophysics Data System (ADS)

    Semerci, Fatih; Yeşilel, Okan Zafer; Soylu, Mustafa Serkan; Yerli, Yusuf; Dal, Hakan

    2014-02-01

    Two new K+/Cu(II) and Zn(II) coordination polymers with pyridine-2,3-dicarboxylate (pydc), {K2[Cu(μ-pydc)2]·3H2O}n (1) and {[Zn(μ-pydc)(H2O)(4-mim)]·H2O}n (2) (4-mim=4-methylimidazole) have been synthesized from zerovalent metal and characterized by IR, EPR spectroscopy, thermal analysis and single crystal X-ray diffraction techniques. In the sandwiched 3D anionic framework of 1, pydc ligands exhibit hexadentate coordination; tridentate coordination bond with Cu(II) and tridentate ionic interaction with K+ ions. {K2[Cu(μ-pydc)2]·3H2O}n shows a rare topology consists of three dimensional (3,4,5)-connected network with the point symbol of {42.6}2{42.84}{43.6.86}2. The distorted square pyramidal geometry of 2 is completed with an nitrogen atom from 4-mim and aqua ligand to form a 1D polynuclear structure. The hydrogen bonds link the 1D chains into 3D architecture. The temperature dependent magnetic property of complex 1 has been studied. Complex 2 exhibits unusual yellow luminescence in the solid state at room temperature.

  19. Design and synthesis of two luminescent Zn(II)-based coordination polymers with different structures regulated by different solvent system

    NASA Astrophysics Data System (ADS)

    Wu, Wei-Ping; Wen, Gui-Lin; Liao, Yi; Wang, Jun; Lu, Lu; Wu, Yu; Xie, Bin

    2016-08-01

    Two new coordination polymers (CPs) [Zn(HL)(H2O)]n (1) and [Zn3(L)2(H2O)2]n·(H2O)n (2), based on a multifunctional ligand combined carboxylate groups and a nitrogen donor group 5-(6-carboxypyridin-2-yl)isophthalic acid (H3L), have been synthesized under different solvent media and fully characterized by powder X-ray diffraction (PXRD), infrared (IR) spectra, elemental analyses (EA) and thermogravimetric analyses (TGA). Single-crystal X-ray diffraction analysis reveals that 1 shows 1D dimeric chain structure, while 2 gives a 3D dense packing framework. Topology analysis illustrates that 2 can be simplified as a 3-nodal net (4, 5, 6-connected net) with the point symbol of {44·62}{46·64}2{48·66·8}. In addition, solid state luminescent properties of two complexes have also been studied in detail, which may act as the potential optical materials.

  20. Synthesis, crystal structures, luminescence and catalytic properties of two d10 metal coordination polymers constructed from mixed ligands

    NASA Astrophysics Data System (ADS)

    Wang, Xiao-xiao; Zhang, Ming-xi; Yu, Baoyi; Van Hecke, Kristof; Cui, Guang-hua

    2015-03-01

    Two new coordination polymers [Cd(bmb)(hmph)]n (1), {[Ag(bmb)]·H2btc}n (2) (bmb = 1,4-bis(2-methylbenzimidazol-1-ylmethyl)benzene, H2hmph = homophthalic acid, H3btc = 1,3,5-benzenetetracarboxylic acid) were synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction methods, IR spectroscopy, TGA, XRPD and elemental analysis. Complex 1 features a 3D threefold interpenetrating dia array with a 4-connected 66 topology. Complex 2 shows a 1D helix chain structure connected by L1 ligands, which is finally extended into a rarely 2D 4L2 supramolecular network via C-H⋯O hydrogen bond interactions. In addition, the luminescence and catalytic properties of the two complexes for the degradation of the methyl orange azo dye in a Fenton-like process were presented. The degradation efficiency of the methyl orange azo dye for 1 and 2 are 56% and 96%, respectively.

  1. Luminescent GdVO4:Sm3+ quantum dots enhance power conversion efficiency of bulk heterojunction polymer solar cells by Förster resonance energy transfer

    NASA Astrophysics Data System (ADS)

    Bishnoi, Swati; Gupta, Vinay; Sharma, Chhavi; Haranath, D.; Naqvi, Sheerin; Kumar, Mahesh; Sharma, Gauri D.; Chand, Suresh

    2016-07-01

    In this work, we report enhanced power conversion efficiency (PCE) of bulk heterojunction polymer solar cells by Förster resonance energy transfer (FRET) from samarium-doped luminescent gadolinium orthovanadate (GdVO4:Sm3+) quantum dots (QDs) to polythieno[3,4-b]-thiophene-co-benzodithiophene (PTB7) polymer. The photoluminescence emission spectrum of GdVO4:Sm3+ QDs overlaps with the absorption spectrum of PTB7, leading to FRET from GdVO4:Sm3+ to PTB7, and significant enhancements in the charge-carrier density of excited and polaronic states of PTB7 are observed. This was confirmed by means of femtosecond transient absorption spectroscopy. The FRET from GdVO4:Sm3+ QDs to PTB7 led to a remarkable increase in the power conversion efficiency (PCE) of PTB7:GdVO4:Sm3+:PC71BM ([6,6]-phenyl-C71-butyric acid methyl ester) polymer solar cells. The PCE in optimized ternary blend PTB7:GdVO4:Sm3+:PC71BM (1:0.1:1.5) is increased to 8.8% from 7.2% in PTB7:PC71BM. This work demonstrates the potential of rare-earth based luminescent QDs in enhancing the PCE of polymer solar cells.

  2. Syntheses, structural analyses and luminescent property of four alkaline-earth coordination polymers

    SciTech Connect

    Zhang, Sheng; Qu, Xiao-Ni; Xie, Gang; Wei, Qing; Chen, San-Ping

    2014-02-15

    Four alkaline-earth coordination polymers, [Ba(Pzdc)(H{sub 2}O)]{sub n} (1), [Ba(Pzdc)]{sub n} (2), [AgSr(Pzdc)(NO{sub 3})(H{sub 2}O)]{sub n} (3), [Ag{sub 2}Ca(Pzdc){sub 2}(H{sub 2}O)]{sub n} (4) (H{sub 2}Pzdc=2, 3-pyrazinedicarboxylic acid) have been synthesized and characterized by single-crystal X-ray diffraction. Compounds 1 and 2 afford 2D layer networks generated by one-dimensional chains containing the [Ba{sub 2}O{sub 11}N] units. Compound 3 is of 2D mixed-metal coordination network formed by one-dimensional chain units, while 4 is of a 3D heterometallic framework. Interestingly, 1 and 2 can undergo reversible SCSC structural transformation upon dehydration/rehydration of coordinated water molecules. In addition, the π–π stacking interactions dominate fluorescent properties of compounds 1 and 2. - Graphical abstract: Four new coordination polymers [Ba(Pzdc)(H{sub 2}O)]{sub n} (1), [Ba(Pzdc)]{sub n} (2), [AgSr(Pzdc)(NO{sub 3})(H{sub 2}O)]{sub n} (3), [Ag{sub 2}Ca(Pzdc){sub 2}(H{sub 2}O)]{sub n} (4) (H{sub 2}Pzdc=2, 3-pyrazinedicarboxylic acid) have been synthesized. Compounds 1–3 display 2D topology structures and compound 4 exhibits a 3D topology structure. Fortunately, 1 and 2 undergo reversible dehydration/rehydration of coordinated water molecules. Display Omitted - Highlights: • All structures are generated by 1D chains. • 1 and 2 show reversible dehydration/rehydration of coordinated water molecules. • The π–π stacking interactions dominate fluorescent properties of compounds 1 and 2.

  3. Two new pyridine-2,3-dicarboxylate coordination polymers prepared from zerovalent metal precursor: Syntheses, luminescent and magnetic properties

    SciTech Connect

    Semerci, Fatih; Yeşilel, Okan Zafer; Soylu, Mustafa Serkan; Yerli, Yusuf; Dal, Hakan

    2014-02-15

    Two new K{sup +}/Cu(II) and Zn(II) coordination polymers with pyridine-2,3-dicarboxylate (pydc), (K{sub 2}[Cu(μ-pydc){sub 2}]·3H{sub 2}O){sub n} (1) and ([Zn(µ-pydc)(H{sub 2}O)(4-mim)]·H{sub 2}O){sub n} (2) (4-mim=4-methylimidazole) have been synthesized from zerovalent metal and characterized by IR, EPR spectroscopy, thermal analysis and single crystal X-ray diffraction techniques. In the sandwiched 3D anionic framework of 1, pydc ligands exhibit hexadentate coordination; tridentate coordination bond with Cu(II) and tridentate ionic interaction with K{sup +} ions. (K{sub 2}[Cu(μ-pydc){sub 2}]·3H{sub 2}O){sub n} shows a rare topology consists of three dimensional (3,4,5)-connected network with the point symbol of (4{sup 2}.6){sub 2}(4{sup 2}.8{sup 4})(4{sup 3}.6.8{sup 6}){sub 2}. The distorted square pyramidal geometry of 2 is completed with an nitrogen atom from 4-mim and aqua ligand to form a 1D polynuclear structure. The hydrogen bonds link the 1D chains into 3D architecture. The temperature dependent magnetic property of complex 1 has been studied. Complex 2 exhibits unusual yellow luminescence in the solid state at room temperature. - Graphical abstract: Two new K{sup +}/Cu(II) and Zn(II) coordination polymers with pyridine-2,3-dicarboxylate (pydc), (K{sub 2}[Cu(μ-pydc){sub 2}]·3H{sub 2}O){sub n} (1) and ([Zn(µ-pydc)(H{sub 2}O)(4-mim)]·H{sub 2}O){sub n} (2) (4-mim=4-methylimidazole) have been synthesized from zerovalent metal and characterized by IR, EPR spectroscopy, thermal analysis and single crystal X-ray diffraction techniques. The water soluble (K{sub 2}[Cu(μ-pydc){sub 2}]·3H{sub 2}O){sub n} shows three dimensional a rare 3,4,5-connected network with the point symbol of (4{sup 2}.6){sub 2}(4{sup 2}.8{sup 4})(4{sup 3}.6.8{sup 6}){sub 2}. The temperature dependent magnetic property of complex 1 has been studied. Complex 2 exhibits unusual yellow luminescence in the solid state at room temperature. Display Omitted - Highlights: • Water

  4. Luminescent detection of hydrazine and hydrazine derivatives

    DOEpatents

    Swager, Timothy M.; Thomas, III, Samuel W.

    2012-04-17

    The present invention generally relates to methods for modulating the optical properties of a luminescent polymer via interaction with a species (e.g., an analyte). In some cases, the present invention provides methods for determination of an analyte by monitoring a change in an optical signal of a luminescent polymer upon exposure to an analyte. Methods of the present invention may be useful for the vapor phase detection of analytes such as explosives and toxins. The present invention also provides methods for increasing the luminescence intensity of a polymer, such as a polymer that has been photobleached, by exposing the luminescent polymer to a species such as a reducing agent.

  5. Facile one-pot preparation and functionalization of luminescent chitosan-poly(methacrylic acid) microspheres based on polymer monomer pairs

    NASA Astrophysics Data System (ADS)

    Guo, Jia; Wang, Changchun; Mao, Weiyong; Yang, Wuli; Liu, Changjia; Chen, Jiyao

    2008-08-01

    In this paper, we present a facile and robust approach to synthesize multifunctional organic/inorganic composite microspheres with chitosan-poly(methacrylic acid) (CS-PMAA) shells and cadmium tellurium/iron oxide nanoparticle cores. Due to the strong electrostatic interaction between the negatively charged nanoparticles and the protonated CS polymers, the CS/nanoparticle complexes were utilized as templates for the subsequent polymerization of methacrylic acid. The resulting composite microspheres with luminescence and magnetic properties have regular morphologies and narrow size distributions. In contrast to previous reports, this route was based on a one-pot strategy without the aid of surfactants, organic solvent, or polymerizable ligands in aqueous solution. The encapsulated CdTe semiconductor nanocrystals inside the microspheres exhibited strong and stable photoluminescence properties in the pH range 5.0-11.0. When the pH was adjusted below 4, the photoluminescence decreased sharply and even quenched completely. However, the weakened fluorescence emission could be recovered to some degree upon an increase of pH above 5. Additionally, when both Fe3O4 and CdTe nanoparticles were encapsulated within CS-PMAA microspheres, the magnetic content of the microspheres could be efficiently controlled by tuning the feeding molar ratio of MAA monomers and glucosamine units of CS. From the preliminary attempts, it was found that the multifunctional microspheres as imaging agents could improve the rate and extent of cellular uptake under short-term exposure to an applied magnetic field, and so exhibit a great potential as bioactive molecule carriers.

  6. A series of coordination polymers based on a V-shaped multicarboxylate and bisimidazole ligands: Synthesis, characterization and luminescent properties

    NASA Astrophysics Data System (ADS)

    Guo, Huadong; Yan, Yongnian; Guo, Xianmin; Wang, Nan; Qi, Yanjuan

    2016-03-01

    Based on a V-shaped multicarboxylic acid and various bisimidazole ligands, six new coordination polymers, namely, [Zn4(otba) (1,4-bix)4]·3H2O (1), [Ni4(otba)2(1,4-bix)3(H2O)2]·2H2O (2), [Zn2(H2otba)2(bib) (H2O)2] (3), [Cd2(H2otba)2(bib)]·2H2O (4), [Zn3(otba)2(bidpe)2(H2O)2] (5), [Ni2(H2otba)2(bidpe)3(H2O)2]·H2O (6) (H4otba = 3,5,3‧,5‧-oxytetrabenzoic acid, 1,4-bix = 1,2-bis(imidazol-1-ylmethyl)benzene, bib = 1,4-bis(imidazol-1-yl)benzene and bidpe = 4,4'-bis(imidazol-1-yl)diphenyl ether) have been hydrothermally synthesized and structurally characterized. Compound 1 displays an uncommon hexanodal 3D 4-connected network. Compound 2 features a trinodal 3D (4, 4, 6)-connected framework. Compound 3 shows an interesting polythreaded 1D→3D species. Compound 4 exhibits a binodal 3D (3, 8)-connected network. Compound 5 displays a three-fold interpenetration of trinodal (3, 3, 4)-connected network. Compound 6 shows a five-fold interpenetration of five-connected bilayer network. The luminescent properties of compounds 1, 3, 4 and 5 were also measured.

  7. High-pressure optical cell system for online luminescence spectrum research

    NASA Astrophysics Data System (ADS)

    Bao, Chengman; Ye, Shuming; Lou, Kaikai; Jiang, Chunyue

    2010-03-01

    An optical cell system was developed for online research into the luminescence spectrum under conditions of extremely high hydrostatic pressure up to 60 MPa. The optical cell, which had three 8 mm thick sapphire windows 16 mm in diameter, was mounted directly onto a fluorescence spectrometer. Hydrostatic pressure was achieved through a hand pump and monitored through a pressure sensor. The optical cell system could be used separately. And more importantly, the system could be connected to a high-pressure flowing system for online flowing luminescence measurement. For system validation, fluorescence spectra of Rose Bengal solution using the high-pressure cell were compared with the standard sample holder. Using the system, fluorescence spectra of Rose Bengal dissolved in distilled water were measured under different pressures at room temperature. The fluorescence intensity of Rose Bengal solution changed with pressures, but the peak positions were almost the same.

  8. High temperature chemically resistant polymer concrete

    DOEpatents

    Sugama, T.; Kukacka, L.E.

    High temperature chemically resistant, non-aqueous polymer concrete composites consist of about 12 to 20% by weight of a water-insoluble polymer binder. The binder is polymerized in situ from a liquid vinyl-type monomer or mixture of vinyl containing monomers such as triallylcyanurate, styrene, acrylonitrile, acrylamide, methacrylamide, methyl-methacrylate, trimethylolpropane trimethacrylate and divinyl benzene. About 5 to 40% by weight of a reactive inorganic filler selected from the group consisting of tricalcium silicate and dicalcium silicate and mixtures containing less than 2% free lime, and about 48 to 83% by weight of silica sand/ and a free radical initiator such as di-tert-butyl peroxide, azobisisobutyronitrile, benzoyl peroxide, lauryl peroxide, other orgaic peroxides and combinations to initiate polymerization of the monomer in the presence of the inorganic filers are used.

  9. Synthesis of highly luminescent cobalt(ii)-bis(8-hydroxyquinoline) nanosheets as isomeric aromatic amine probes

    NASA Astrophysics Data System (ADS)

    Li, Haibing; Li, Yuling

    2009-09-01

    Highly luminescent and water-soluble cobalt(ii)-bis(8-hydroxyquinoline) (CoQ2) nanosheets have been successfully synthesized via a simple, rapid sonochemical method. The water-soluble CoQ2 nanosheets were characterized by luminescence spectroscopy, UV-vis spectroscopy, FT-IR spectroscopy and transmission electron microscopy (TEM). The CoQ2 nanosheets allow highly sensitive and selective determination of p-nitroaniline via fluorescence quenching. Under optimal conditions, the relative fluorescence intensities of nanosheets decreased linearly with increasing p-nitroaniline. However, the sensitivity of CoQ2 nanosheets toward other aromatic amines including o-diaminobenzene, m-diaminobenzene, p-diaminobenzene, p-toluidine, o-nitroaniline, m-nitroaniline, p-chloroaniline and aniline is negligible. It is found that p-nitroaniline can quench the luminescence of CoQ2 nanosheets in a concentration-dependent manner that is best described by a Stern-Volmer-type equation. The possible underlying mechanism is discussed.Highly luminescent and water-soluble cobalt(ii)-bis(8-hydroxyquinoline) (CoQ2) nanosheets have been successfully synthesized via a simple, rapid sonochemical method. The water-soluble CoQ2 nanosheets were characterized by luminescence spectroscopy, UV-vis spectroscopy, FT-IR spectroscopy and transmission electron microscopy (TEM). The CoQ2 nanosheets allow highly sensitive and selective determination of p-nitroaniline via fluorescence quenching. Under optimal conditions, the relative fluorescence intensities of nanosheets decreased linearly with increasing p-nitroaniline. However, the sensitivity of CoQ2 nanosheets toward other aromatic amines including o-diaminobenzene, m-diaminobenzene, p-diaminobenzene, p-toluidine, o-nitroaniline, m-nitroaniline, p-chloroaniline and aniline is negligible. It is found that p-nitroaniline can quench the luminescence of CoQ2 nanosheets in a concentration-dependent manner that is best described by a Stern-Volmer-type equation

  10. Multifunctional sensing ability of a new Pt/Zn-based luminescent coordination polymer.

    PubMed

    Kobayashi, Atsushi; Hara, Hirofumi; Noro, Shin-Ichiro; Kato, Masako

    2010-04-14

    We synthesized a new Pt/Zn-based coordination polymer, {Zn[Pt(CN)(2)(5,5'-dcbpy)].4H(2)O}(n), (5,5'-H(2)dcbpy = 5,5'-dicarboxy-2,2'-bipyridine), which exhibits reversible colour changes in response to temperature change or exposure to chemical vapours and liquids. Such chromic behaviour shows promise for sensing not only changes in temperature but also for detecting chemical solvents and vapours. The single crystal X-ray structure indicates that one-dimensional coordination polymeric chains formed by an alternating arrangement of [Zn(H(2)O)(3)](2+) and [Pt(CN)(2)(5,5'-dcbpy)](2-) stacked to produce moderate metallophilic interactions between the Pt(ii) ions. Thermogravimetric analysis and water vapour adsorption measurements show that both the crystal water and water coordinated to Zn(ii) ions can be removed and re-adsorbed reversibly by heating or under vacuum. Emission spectra at various temperatures and/or in the presence of vapours or liquids reveal that the complex exhibits thermochromic and solvatochromic-like behaviours, with the emission band shifting between 616 and 671 nm. IR spectroscopy and powder X-ray diffraction measurements suggest that this multichromic behaviour is a result of the cooperative phenomena of water adsorption/desorption around the Zn(ii) ions and the modification of the metallophilic interaction. PMID:20379533

  11. Influence of conformational flexibility on self-assembly and luminescence properties of lanthanide coordination polymers with flexible exo-bidentate biphenol derivatives.

    PubMed

    Guo, Yanling; Dou, Wei; Zhou, Xiaoyan; Liu, Weisheng; Qin, Wenwu; Zang, Zhipeng; Zhang, Hongrui; Wang, Daqi

    2009-04-20

    To explore how nonplanar conformational distortions affect supramolecular self-assembly and properties of lanthanide complexes, we have designed and synthesized two new flexible exo-bidentate ligands derived from biphenol featuring two salicylamide pendant arms, 2,2'-bis{[(2'-benzylaminoformyl)phenoxyl]ethoxyl}-1,1'-biphenylene (L(I)) and 5,5'-dibromo-2,2'-bis{[(2'-benzylaminoformyl)phenoxyl]ethoxyl}-1,1'-biphenylene (L(II)). These two structurally related ligands can have different conformations and are used for constructing diverse lanthanide polymers with interesting luminescence properties. Among two series of lanthanide nitrate complexes which have been characterized by elemental analysis, X-ray powder diffraction, and IR spectroscopy, four new coordination polymers have been determined using X-ray diffraction analysis. The coordination polymer type {Ln(2)(NO(3))(6)(L(I))(3).3H(2)O}(infinity) (Ln = Nd, Sm, Eu, Gd, Tb or Dy) displays a two-dimensional honeycomb-like framework in the ab plane, which can be regarded as a (6,3) topological network with neodymium atoms acting as "three-connected" centers. In contrast, the coordination polymer types {[Nd(NO(3))(3)(L(II))(CH(3)OH)] x CH(3)OH}(infinity) and [Ln(NO(3))(3)(L(II))(C(2)H(5)OH)](infinity) (Ln = Sm, Eu, Gd, Tb or Dy) possess single-stranded helix chains which can be further connected through intermolecular hydrogen bonds to form two-dimensional supramolecular sheets. The photophysical properties of trivalent Sm, Eu, Tb, and Dy complexes at room temperature were investigated. The present work substantiates the claim that the supramolecular structure as well as the luminescence properties of the coordination polymer can be tuned by controlling the conformational distortion of a nonplanar flexible ligand in the supramolecular self-assembly. PMID:19290612

  12. High-Temperature Capacitor Polymer Films

    NASA Astrophysics Data System (ADS)

    Tan, Daniel; Zhang, Lili; Chen, Qin; Irwin, Patricia

    2014-12-01

    Film capacitor technology has been under development for over half a century to meet various applications such as direct-current link capacitors for transportation, converters/inverters for power electronics, controls for deep well drilling of oil and gas, direct energy weapons for military use, and high-frequency coupling circuitry. The biaxially oriented polypropylene film capacitor remains the state-of-the-art technology; however, it is not able to meet increasing demand for high-temperature (>125°C) applications. A number of dielectric materials capable of operating at high temperatures (>140°C) have attracted investigation, and their modifications are being pursued to achieve higher volumetric efficiency as well. This paper highlights the status of polymer dielectric film development and its feasibility for capacitor applications. High-temperature polymers such as polyetherimide (PEI), polyimide, and polyetheretherketone were the focus of our studies. PEI film was found to be the preferred choice for high-temperature film capacitor development due to its thermal stability, dielectric properties, and scalability.

  13. Non-leachable highly luminescent ordered mesoporous SiO2 spherical particles

    NASA Astrophysics Data System (ADS)

    Rocha, L. A.; Caiut, J. M. A.; Messaddeq, Y.; Ribeiro, S. J. L.; Martines, M. A. U.; Freiria, J. do C.; Dexpert-Ghys, J.; Verelst, M.

    2010-04-01

    Ordered mesoporous highly luminescent SiO2 particles have been synthesized by spray pyrolysis from solutions containing tetraethylorthosilicate (TEOS) and either cetyltrimethylammonium bromide (CTAB) or the block copolymer Pluronic F-68 as structure-directing agents. Rhodamine B (RhB)-containing samples were prepared by using a simple wet impregnation method followed by the growing of a second silica shell in order to prevent leaching of the dye. The obtained materials were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder x-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV-vis) and photoluminescence (PL). Powders with polydisperse spherical grains were obtained displaying an ordered hexagonal array of mesochannels. Luminescence results reveal that RhB molecules have been successfully encapsulated into the channels of mesoporous particles as monomeric species and that a well-defined silica coating hindered dye leaching.

  14. Highly Luminescent, Water-Soluble Lanthanide Fluorobenzoates: Syntheses, Structures and Photophysics, Part I: Lanthanide Pentafluorobenzoates.

    PubMed

    Kalyakina, Alena S; Utochnikova, Valentina V; Bushmarinov, Ivan S; Ananyev, Ivan V; Eremenko, Igor L; Volz, Daniel; Rönicke, Franziska; Schepers, Ute; Van Deun, Rik; Trigub, Alexander L; Zubavichus, Yan V; Kuzmina, Natalia P; Bräse, Stefan

    2015-12-01

    Highly luminescent, photostable, and soluble lanthanide pentafluorobenzoates have been synthesized and thoroughly characterized, with a focus on Eu(III) and Tb(III) complexes as visible emitters and Nd(III) , Er(III) , and Yb(III) complexes as infrared emitters. Investigation of the crystal structures of the complexes in powder form and as single crystals by using X-ray diffraction revealed five different structural types, including monomeric, dimeric, and polymeric. The local structure in different solutions was studied by using X-ray absorption spectroscopy. The photoluminescence quantum yields (PLQYs) of terbium and europium complexes were 39 and 15 %, respectively; the latter value was increased almost twice by using the heterometallic complex [Tb0.5 Eu0.5 (pfb)3 (H2 O)] (Hpfb=pentafluorobenzoic acid). Due to the effectively utilized sensitization strategy (pfb)(-) →Tb→Eu, a pure europium luminescence with a PLQY of 29 % was achieved. PMID:26489887

  15. High-throughput spectral system for interrogation of dermally-implanted luminescent sensors.

    PubMed

    Long, Ruiqi; McShane, Mike

    2012-01-01

    Ratiometric luminescent microparticle sensors have been developed for sensing biochemical targets such as glucose in interstitial fluid, enabling use of dermal implants for on-demand monitoring. For these sensor systems to be deployed in vivo, a matched optoelectronic system for interrogation of dermally-implanted sensors was previously designed, constructed, and evaluated experimentally. During evaluation experiments, it revealed that the system efficiency was compromised by losses due to fiber connections of a commercial spectrometer. In this work, a high-throughput spectral system was presented to solve the photon loss problem. This system was designed, constructed, and tested. The throughput was around hundred time more than the previous system we used, and it was cost-effective, as well. It enables use of an integrated system for excitation, collection and measurement of luminescent emission, and will be used as a tool for in vivo studies with animal models or human subjects. PMID:23366396

  16. High-Temperature Shape Memory Polymers

    NASA Technical Reports Server (NTRS)

    Yoonessi, Mitra; Weiss, Robert A.

    2012-01-01

    physical conformation changes when exposed to an external stimulus, such as a change in temperature. Such materials have a permanent shape, but can be reshaped above a critical temperature and fixed into a temporary shape when cooled under stress to below the critical temperature. When reheated above the critical temperature (Tc, also sometimes called the triggering or switching temperature), the materials revert to the permanent shape. The current innovation involves a chemically treated (sulfonated, carboxylated, phosphonated, or other polar function group), high-temperature, semicrystalline thermoplastic poly(ether ether ketone) (Tg .140 C, Tm = 340 C) mix containing organometallic complexes (Zn++, Li+, or other metal, ammonium, or phosphonium salts), or high-temperature ionic liquids (e.g. hexafluorosilicate salt with 1-propyl-3- methyl imidazolium, Tm = 210 C) to form a network where dipolar or ionic interactions between the polymer and the low-molecular-weight or inorganic compound forms a complex that provides a physical crosslink. Hereafter, these compounds will be referred to as "additives". The polymer is semicrystalline, and the high-melt-point crystals provide a temporary crosslink that acts as a permanent crosslink just so long as the melting temperature is not exceeded. In this example case, the melting point is .340 C, and the shape memory critical temperature is between 150 and 250 C. PEEK is an engineering thermoplastic with a high Young fs modulus, nominally 3.6 GPa. An important aspect of the invention is the control of the PEEK functionalization (in this example, the sulfonation degree), and the thermal properties (i.e. melting point) of the additive, which determines the switching temperature. Because the compound is thermoplastic, it can be formed into the "permanent" shape by conventional plastics processing operations. In addition, the compound may be covalently cross - linked after forming the permanent shape by S-PEEK by applying ionizing

  17. High temperature polymers - A review of novel thermally stable hexafluoroisopropylidene-containing polymers

    NASA Technical Reports Server (NTRS)

    Kane, K. M.; Cassidy, P. E.; Tullos, G. L.; Reynolds, D. W.

    1990-01-01

    The synthesis and properties to date of several novel HFIP-containing polymers and copolymers are presented. Thermal analyses of polyether ketones (PEK), aromatic polyesters, and polymers from a novel 18F-diacid were performed on a thermal analyzer. All three polymer types exhibited enhanced solubility, thermal stability, and low dielectric constants that are predicted for polymers containing the HFIP moiety. The moderate thermal stability observed in the polymers derived from the 18F-diacid is attributed to the oxidatively weak methylene linkage between the HFIP groups and the phenyl rings. PEKs and polyarylates show potential as high emissivity coatings under conditions where atomic oxygen is present.

  18. Synthesis, crystal structures and luminescent properties of two 4d-4f Ln-Ag heterometallic coordination polymers based on anion template

    SciTech Connect

    Fan, Le-Qing; Chen, Yuan; Wu, Ji-Huai; Huang, Yun-Fang

    2011-04-15

    Two new 4d-4f Ln-Ag heterometallic coordination polymers, {l_brace}[Ln{sub 3}Ag{sub 5}(IN){sub 10}(H{sub 2}O){sub 7}].4(ClO{sub 4}).4(H{sub 2}O){r_brace}{sub n} (Ln=Eu (1) and Sm (2), HIN=isonicotinic acid), have been synthesized under hydrothermal conditions by reactions of Ln{sub 2}O{sub 3}, AgNO{sub 3}, HIN and HClO{sub 4}, and characterized by elemental analysis, IR, thermal analysis and single-crystal X-ray diffraction. It is proved that HClO{sub 4} not only adjusts the pH value of the reaction mixture, but also acts as anion template. The structure determination reveals that 1 and 2 are isostructural and feature a novel two-dimensional (2D) layered hetrometallic structure constructed from one-dimensional Ln-carboxylate chains and pillared Ag(IN){sub 2} units. The 2D layers are further interlinked through Ag...Ag and Ag...O(ClO{sub 4}{sup -}) multiple weak interactions, which form a rare Ag-ClO{sub 4} ribbon in lanthanide-transition metal coordination polymers, to give rise to a three-dimensional supramolecular architecture. Moreover, the luminescent properties of these two compounds have also been investigated at room temperature. -- Graphical abstract: Two new anion-templated 2D 4d-4f Ln-Ag heterometallic coordination polymers based on novel lanthanide-carboxylate chains and pillared Ag(IN){sub 2} units, {l_brace}[Ln{sub 3}Ag{sub 5}(IN){sub 10}(H{sub 2}O){sub 7}].4(ClO{sub 4}).4(H{sub 2}O){r_brace}{sub n} (Ln=Eu (1) and Sm (2), HIN=isonicotinic acid), have been hydrothermally synthesized and structurally characterized. 1 and 2 exhibit good luminescent properties. Display Omitted Research highlights: > Two 2D Eu (Sm)-Ag coordination polymers templated by perchlorate anion have been synthesized. > Polymers consist of novel 1D lanthanide-carboxylate chains. > In both structures, there are rare Ag...Ag and Ag...O(ClO{sub 4}{sup -}) multiple weak interactions. > Both compounds exhibit good luminescent properties.

  19. New monomers for high performance polymers

    NASA Technical Reports Server (NTRS)

    Gratz, Roy F.

    1993-01-01

    This laboratory has been concerned with the development of new polymeric materials with high thermo-oxidative stability for use in the aerospace and electronics industries. Currently, there is special emphasis on developing matrix resins and composites for the high speed civil transport (HSCT) program. This application requires polymers that have service lifetimes of 60,000 hr at 350 F (177 C) and that are readily processible into void-free composites, preferably by melt-flow or powder techniques that avoid the use of high boiling solvents. Recent work has focused on copolymers which have thermally stable imide groups separated by flexible arylene ether linkages, some with trifluoromethyl groups attached to the aromatic rings. The presence of trifluoromethyl groups in monomers and polymers often improves their solubility and processibility. The goal of this research was to synthesize several new monomers containing pendant trifluoromethyl groups and to incorporate these monomers into new imide/arylene ether copolymers. Initially, work was begun on the synthesis of three target compounds. The first two, 3,5-dihydroxybenzo trifluoride and 3-amino 5-hydroxybenzo trifluoride, are intermediates in the synthesis of more complex monomers. The third, 3,5-bis (3-amino-phenoxy) benzotrifluoride, is an interesting diamine that could be incorporated into a polyimide directly.

  20. Monitoring Delamination of Thermal Barrier Coatings During Interrupted High-Heat-Flux Laser Testing using Luminescence Imaging

    NASA Technical Reports Server (NTRS)

    Eldridge, Jeffrey I.; Zhu, Dongming; Wolfe, Douglas E.

    2011-01-01

    This presentation showed progress made in extending luminescence-base delamination monitoring to TBCs exposed to high heat fluxes, which is an environment that much better simulates actual turbine engine conditions. This was done by performing upconversion luminescence imaging during interruptions in laser testing, where a high-power CO2 laser was employed to create the desired heat flux. Upconverison luminescence refers to luminescence where the emission is at a higher energy (shorter wavelength) than the excitation. Since there will be negligible background emission at higher energies than the excitation, this methods produces superb contrast. Delamination contrast is produced because both the excitation and emission wavelengths are reflected at delamination cracks so that substantially higher luminescence intensity is observed in regions containing delamination cracks. Erbium was selected as the dopant for luminescence specifically because it exhibits upconversion luminescence. The high power CO2 10.6 micron wavelength laser facility at NASA GRC was used to produce the heat flux in combination with forced air backside cooling. Testing was performed at a lower (95 W/sq cm) and higher (125 W/sq cm) heat flux as well as furnace cycling at 1163C for comparison. The lower heat flux showed the same general behavior as furnace cycling, a gradual, "spotty" increase in luminescence associated with debond progression; however, a significant difference was a pronounced incubation period followed by acceleration delamination progression. These results indicate that extrapolating behavior from furnace cycling measurements will grossly overestimate remaining life under high heat flux conditions. The higher heat flux results were not only accelerated, but much different in character. Extreme bond coat rumpling occurred, and delamination propagation extended over much larger areas before precipitating macroscopic TBC failure. This indicates that under the higher heat flux (and

  1. Anaerobic polymers as high vacuum leak sealants

    NASA Technical Reports Server (NTRS)

    Kendall, B. R. F.

    1982-01-01

    Anaerobic polymers are useful as solventless leak sealants with good vacuum properties at moderate temperatures. Loctite 290 can seal leaks in a range generally encountered in carefully constructed ultrahigh vacuum and high vacuum systems. It was found that small leaks are sealed best under vacuum, whereas large leaks should be sealed at atmospheric pressure. The high-temperature behavior of Loctite 290 is limited by its fast cure, which prevents deep penetration into small leaks; cracking eventually occurs at the entrance to the leak. Repeated thermal cycling to about 300 C is possible, however, provided viscosity, curing time, and leak size are properly matched to ensure penetration into the body of the leak. This may require special formulations for high temperature vacuum applications.

  2. Is higher ratio of monoclinic to tetragonal in LaVO4 a better luminescence host? Redispersion and polymer film formation.

    PubMed

    Okram, Reena; Yaiphaba, Ningombam; Ningthoujam, Raghumani Singh; Singh, Nongmaithem Rajmuhon

    2014-07-21

    Crystalline LaVO4:Eu(3+) nanophosphors (NPs) codoped with metal ions (M(n+) = Li(+), Sr(2+), and Bi(3+)) are prepared in ethylene glycol (EG) medium at temperature ∼140 °C in 3 h. A mixture of monoclinic and tetragonal phases is observed. The ratio of tetragonal to monoclinic phases increases with increase of Li(+) and Sr(2+) concentration, but this is opposite in case of Bi(3+) concentration. Lattice expansion occurs in the case of Li(+) and Sr(2+) codoping. Li(+) ions occupy the interstitial sites instead of La(3+) sites. Lattice contraction occurs in case of Bi(3+) codoping indicating substitution of La(3+) sites. Luminescence intensity is improved by codoping of M(n+) irrespective of crystal structure. Charges of Li(+) and Sr(2+) are different from that of La(3+) (host lattice), whereas the charge of Bi(3+) is same as that of La(3+). One interesting observation is in magnetic dipole transition that the intensity of the peak at 594 nm is more than that at 587 nm in the case of charge imbalance, whereas the reverse occurs in the case of charge balance. LaVO4:Eu(3+) nanophosphors prepared in water medium have more luminescence intensity when compared to those prepared in ethylene glycol, and this is related to variation of ratio of tetragonal to monoclinic phases. The luminescence intensity is also enhanced as annealing temperature increases from 600 to 800 °C due to the improved crystallinity. Lifetime data are analyzed on the basis of exponential and nonexponential decay equations. Samples are dispersible in polar medium due to capping of particles by EG. Polymer films are prepared by dispersion of NPs in poly(vinyl alcohol), and extra borax is added in order to make cross-link between polymer molecules. Samples of NPs in the forms of powder, dispersion in liquid medium, and film show the red emission. PMID:24963837

  3. High temperature polymer dielectric film insulation

    NASA Technical Reports Server (NTRS)

    Jones, Robert J.

    1994-01-01

    PFPI polymers were invented in the late 1970's. Assessment of emerging requirements has dictated that 300 C performance is the goal for next generation wire insulation. TRW PFPI as superior 300 C polymer candidates is presented. Included is a comparison of promising PFPI film properties with Kapton. Also included are the promising bulk polymer or coating properties.

  4. Deep levels in high resistivity GaN detected by thermally stimulated luminescence and first-principles calculations

    NASA Astrophysics Data System (ADS)

    Gai, Yanqin; Li, Jingbo; Hou, Qifeng; Wang, Xiaoliang; Xiao, Hongling; Wang, Cuimei; Li, Jinmin

    2009-08-01

    Thermally stimulated luminescence spectroscopy has been applied to study the deep centres in unintentionally doped high resistivity GaN epilayers grown by the metal organic chemical vapour deposition method on c-sapphire substrates. Two trap states with activation energies of 0.12 and 0.62 eV are evaluated from two luminescence peaks at 141.9 and 294.7 K in the luminescence curve. Our spectroscopy measurement, in combination with more accurate first-principles studies, provided insights into the microscopic origin of these levels. Our investigations suggest that the lower level at 0.12 eV might originate from CN, which behaves as a hole trap state; the deeper level at 0.62 eV can be correlated with VGa that corresponds to the yellow luminescence band observed in low-temperature photoluminescence spectra.

  5. Two one-dimensional d10-metal coordination polymers based on polydentate Schiff-base ligand: Synthesis, crystal structure and luminescent properties

    NASA Astrophysics Data System (ADS)

    Niu, Wei-Jia; Wang, Jun-Li; Bai, Yan; Dang, Dong-Bin

    2012-06-01

    Two one-dimensional d10-metal coordination polymers {[AgL(H2O)]2[AgL(NO3)]2(NO3)2L(H2O)2}n (1) and [ZnLCl2]n (2) (L = N,N'-bis-(1-pyridin-4-yl-ethylidene)-hydrazine) have been synthesized and characterized by IR, elemental analysis, TG technique, XRPD and X-ray crystallography. Polymer 1 contains two types of 1D Ag-double-chain units. Ag(1)-double-chain unit is formed by linking two adjacent Ag(1)-L-chains through face-to-face π⋯π interactions, while Ag(2)-double-chain unit is formed through the combination of coordinating NO3- anions bridging interactions and π⋯π interactions between two adjacent Ag(2)-L-chains. Free ligands interact with the adjacent Ag(1)-double-chain units and Ag(2)-double-chain units to form a 3D supramolecular structure through multiform hydrogen bonds. For polymer 2, each ligand acts as a bis-monodentate bridging ligand to bind adjacent Zn(II) centers forming a one-dimensional chain structure. Furthermore, 1D chain is held together with its neighboring ones via Csbnd H⋯π interactions. The luminescent properties of the polymers 1 and 2 were investigated in the solid state at room temperature.

  6. Highly Luminescent Lanthanide Complexes of 1 Hydroxy-2-pyridinones

    SciTech Connect

    University of California, Berkeley; Lawrence National Laboratory; Raymond, Kenneth; Moore, Evan G.; Xu, Jide; Jocher, Christoph J.; Castro-Rodriguez, Ingrid; Raymond, Kenneth N.

    2007-11-01

    The synthesis, X-ray structure, stability, and photophysical properties of several trivalent lanthanide complexes formed from two differing bis-bidentate ligands incorporating either alkyl or alkyl ether linkages and featuring the 1-hydroxy-2-pyridinone (1,2-HOPO) chelate group in complex with Eu(III), Sm(III) and Gd(III) are reported. The Eu(III) complexes are among some of the best examples, pairing highly efficient emission ({Phi}{sub tot}{sup Eu} {approx} 21.5%) with high stability (pEu {approx} 18.6) in aqueous solution, and are excellent candidates for use in biological assays. A comparison of the observed behavior of the complexes with differing backbone linkages shows remarkable similarities, both in stability and photophysical properties. Low temperature photophysical measurements for a Gd(III) complex were also used to gain insight into the electronic structure, and were found to agree with corresponding TD-DFT calculations for a model complex. A comparison of the high resolution Eu(III) emission spectra in solution and from single crystals also revealed a more symmetric coordination geometry about the metal ion in solution due to dynamic rotation of the observed solid state structure.

  7. Highly luminescent and color-tunable salicylate ionic liquids

    DOE PAGESBeta

    Campbell, Paul S.; Yang, Mei; Pitz, Demian; Cybinska, Joanna; Mudring, Anja -Verena

    2014-03-11

    High quantum yields of up to 40.5 % can be achieved in salicylate-bearing ionic liquids. A range of these ionic liquids have been synthesized and their photoluminescent properties studied in detail. The differences noted can be related back to the structure of the ionic liquid cation and possible interionic interactions. It is found that shifts of emission, particularly in the pyridinium-based ionic liquids, can be related to cation–anion pairing interactions. Furthermore, facile and controlled emission color mixing is demonstrated through combining different ILs, with emission colors ranging from blue to yellow.

  8. Highly luminescent and color-tunable salicylate ionic liquids.

    PubMed

    Campbell, Paul S; Yang, Mei; Pitz, Demian; Cybinska, Joanna; Mudring, Anja-Verena

    2014-04-14

    High quantum yields of up to 40.5% can be achieved in salicylate-bearing ionic liquids. A range of these ionic liquids have been synthesized and their photoluminescent properties studied in detail. The differences noted can be related back to the structure of the ionic liquid cation and possible interionic interactions. It is found that shifts of emission, particularly in the pyridinium-based ionic liquids, can be related to cation-anion pairing interactions. Facile and controlled emission color mixing is demonstrated through combining different ILs, with emission colors ranging from blue to yellow. PMID:24615781

  9. Controllable synthesis of Zn/Cd(ii) coordination polymers: dual-emissive luminescent properties, and tailoring emission tendency under varying excitation energies.

    PubMed

    Xing, Kai; Fan, Ruiqing; Gao, Song; Wang, Xinming; Du, Xi; Wang, Ping; Fang, Ru; Yang, Yulin

    2016-03-21

    Based on a new asymmetric semi-rigid V-shaped tricarboxylate ligand 3-(2',3'-dicarboxylphenoxy)benzoic acid (H3dpob), a series of zinc/cadmium(ii) coordination polymers, {[Cd(Hdpob)(H2O)3]·H2O}n (1), [Cd(Hdpob)(bib)]n (2), [Zn(Hdpob)(bib)0.5]n (3), {[Cd1.5(dpob)(2,2'-bipy)]·0.5H2O}2n (4) and {[Cd3(dpob)2(4,4'-bipy)2]·3H2O}n (5) [bib = 1,4-bis(1-imidazolyl)benzene; 2,2'-bipy = 2,2'-bipyridine; 4,4'-bipy = 4,4'-bipyridine], have been successfully synthesized via hydro(solvo)thermal reactions. 1 forms a three dimensional (3D) supramolecular structure linked by two types of intermolecular hydrogen bonds based on zig-zag 1D chains, whereas 2 and 3 are obtained with a similar 2D layer structure by the same ligands and further connected into a 3D structure through hydrogen bonds. 4 displays a homochiral 2D structure though two achiral ligands 2,2'-bipy and H3dpob, which contains right-handed helical infinite chains. 5 is a 3D structure containing 2D metal-pyridine layer motifs, which are further pillared by beaded dpob(3-) ligands to complete the structure and form a 6-connected pcu (primitive cubic) net. In DMSO solvent, 1-5 illustrate dual-emission properties but have different low-energy emission (LE) intensities relatively. Extraordinarily, the difference resulting from central metals between 2 and 3 makes the intensity of LE dramatically enhanced and quenched. In this regard, the luminescence of 2 and 3 can be tuned between blue and green regions by varying the excitation light, and the tuning tendency can be tailored with inverse directions. Comparing their tunable-sensitivity to energy quantitatively, the theoretical calculation displays that 3 (4.29%) is little higher than 2 (3.59%) in a relative lower excitation wavelength zone. Meanwhile, five coordination polymers show distinct luminescence thermochromism in the solid state. When the temperature decreases from 298 K to 77 K, the red-shift from blue/green to the pure yellow light region is highlighted. The

  10. Recovery of petroleum with chemically treated high molecular weight polymers

    SciTech Connect

    Gibb, C.L.; Rhudy, J.S.

    1980-11-18

    Plugging of reservoirs with high molecular weight polymers, e.g. Partially hydrolyzed polyacrylamide, is overcome by chemically treating a polymer having an excessively high average molecular weight prior to injection into a reservoir with an oxidizing chemical, e.g. sodium hypochlorite, and thereafter incorporating a reducing chemical, e.g., sodium sulfite, to stop degradation of the polymer when a desired lower average molecular weight and flooding characteristics are attained.

  11. Activators of photoluminescence in calcite: evidence from high-resolution, laser-excited luminescence spectroscopy

    USGS Publications Warehouse

    Pedone, V.A.; Cercone, K.R.; Burruss, R.C.

    1990-01-01

    Laser-excited luminescence spectroscopy of a red-algal, biogenic calcite and a synthetic Mn-calcite can make the distinction between organic and trace-element activators of photoluminescence. Organic-activated photoluminescence in biogenic calcite is characterized by significant peak shifts and increasing intensity with shorter-wavelength excitation and by significant decreases in intensity after heating to ??? 400??C. In contrast, Mn-activated photoluminescence shows no peak shift, greatest intensity under green excitation and limited changes after heating. Examination of samples with a high-sensitivity spectrometer using several wavelengths of exciting light is necessary for identification of photoluminescence activators. ?? 1990.

  12. Flexible, highly efficient all-polymer solar cells

    NASA Astrophysics Data System (ADS)

    Kim, Taesu; Kim, Jae-Han; Kang, Tae Eui; Lee, Changyeon; Kang, Hyunbum; Shin, Minkwan; Wang, Cheng; Ma, Biwu; Jeong, Unyong; Kim, Taek-Soo; Kim, Bumjoon J.

    2015-10-01

    All-polymer solar cells have shown great potential as flexible and portable power generators. These devices should offer good mechanical endurance with high power-conversion efficiency for viability in commercial applications. In this work, we develop highly efficient and mechanically robust all-polymer solar cells that are based on the PBDTTTPD polymer donor and the P(NDI2HD-T) polymer acceptor. These systems exhibit high power-conversion efficiency of 6.64%. Also, the proposed all-polymer solar cells have even better performance than the control polymer-fullerene devices with phenyl-C61-butyric acid methyl ester (PCBM) as the electron acceptor (6.12%). More importantly, our all-polymer solar cells exhibit dramatically enhanced strength and flexibility compared with polymer/PCBM devices, with 60- and 470-fold improvements in elongation at break and toughness, respectively. The superior mechanical properties of all-polymer solar cells afford greater tolerance to severe deformations than conventional polymer-fullerene solar cells, making them much better candidates for applications in flexible and portable devices.

  13. Flexible, highly efficient all-polymer solar cells

    PubMed Central

    Kim, Taesu; Kim, Jae-Han; Kang, Tae Eui; Lee, Changyeon; Kang, Hyunbum; Shin, Minkwan; Wang, Cheng; Ma, Biwu; Jeong, Unyong; Kim, Taek-Soo; Kim, Bumjoon J.

    2015-01-01

    All-polymer solar cells have shown great potential as flexible and portable power generators. These devices should offer good mechanical endurance with high power-conversion efficiency for viability in commercial applications. In this work, we develop highly efficient and mechanically robust all-polymer solar cells that are based on the PBDTTTPD polymer donor and the P(NDI2HD-T) polymer acceptor. These systems exhibit high power-conversion efficiency of 6.64%. Also, the proposed all-polymer solar cells have even better performance than the control polymer-fullerene devices with phenyl-C61-butyric acid methyl ester (PCBM) as the electron acceptor (6.12%). More importantly, our all-polymer solar cells exhibit dramatically enhanced strength and flexibility compared with polymer/PCBM devices, with 60- and 470-fold improvements in elongation at break and toughness, respectively. The superior mechanical properties of all-polymer solar cells afford greater tolerance to severe deformations than conventional polymer-fullerene solar cells, making them much better candidates for applications in flexible and portable devices. PMID:26449658

  14. Highly crosslinked silicon polymers for gas chromatography columns

    NASA Technical Reports Server (NTRS)

    Shen, Thomas C. (Inventor)

    1994-01-01

    A new highly crosslinked silicone polymer particle for gas chromatography application and a process for synthesizing such copolymer are described. The new copolymer comprises vinyltriethoxysilane and octadecyltrichlorosilane. The copolymer has a high degree of crosslinking and a cool balance of polar to nonpolar sites in the porous silicon polymer assuring fast separation of compounds of variable polarity.

  15. Synthesis of Luminescent Graphene Quantum Dots with High Quantum Yield and Their Toxicity Study

    PubMed Central

    Jiang, Dan; Chen, Yunping; Li, Na; Li, Wen; Wang, Zhenguo; Zhu, Jingli; Zhang, Hong; Liu, Bin; Xu, Shan

    2015-01-01

    High fluorescence quantum yield graphene quantum dots (GQDs) have showed up as a new generation for bioimaging. In this work, luminescent GQDs were prepared by an ameliorative photo-Fenton reaction and a subsequent hydrothermal process using graphene oxide sheets as the precursor. The as-prepared GQDs were nanomaterials with size ranging from 2.3 to 6.4 nm and emitted intense green luminescence in water. The fluorescence quantum yield was as high as 24.6% (excited at 340 nm) and the fluorescence was strongest at pH 7. Moreover, the influences of low-concentration (12.5, 25 μg/mL) GQDs on the morphology, viability, membrane integrity, internal cellular reactive oxygen species level and mortality of HeLa cells were relatively weak, and the in vitro imaging demonstrated GQDs were mainly in the cytoplasm region. More strikingly, zebrafish embryos were co-cultured with GQDs for in vivo imaging, and the results of heart rate test showed the intake of small amounts of GQDs brought little harm to the cardiovascular of zebrafish. GQDs with high quantum yield and strong photoluminescence show good biocompatibility, thus they show good promising for cell imaging, biolabeling and other biomedical applications. PMID:26709828

  16. 2D l-Di-toluoyl-tartaric acid Lanthanide Coordination Polymers: Toward Single-component White-Light and NIR Luminescent Materials.

    PubMed

    Niu, Wan-Ying; Sun, Jing-Wen; Yan, Peng-Fei; Li, Yu-Xin; An, Guang-Hui; Li, Guang-Ming

    2016-02-01

    A series of five l-di-p-toluoyl-tartaric acid (l-DTTA) lanthanide coordination polymers, namely {[Ln4 K(4)  L6 (H2 O)x ]⋅yH2 O}n , [Ln=Dy (1), x=24, y=12; Ln=Ho (2), x=23, y=12; Ln=Er (3), x=24, y=12; Ln=Yb (4), x=24, y=11; Ln=Lu (5), x=24, y=12] have been isolated by simple reactions of H2 L (H2 L= L-DTTA) with LnCl3 ⋅6 H2 O at ambient temperature. X-ray crystallographic analysis reveals that complexes 1-5 feature two-dimensional (2D) network structures in which the Ln(3+) ions are bridged by carboxylate groups of ligands in two unique coordinated modes. Luminescent spectra demonstrate that complex 1 realizes single-component white-light emission, while complexes 2-4 exhibit a characteristic near-infrared (NIR) luminescence in the solid state at room temperature. PMID:26663517

  17. Fabrication and characterization of long-persistent luminescence/polymer (Ca2MgSi2O7:Eu2+, Dy3+/PLA) composite fibers by electrospinning

    NASA Astrophysics Data System (ADS)

    Ye, Feng; Dong, Shengjie; Tian, Zhe; Yao, Sijia; Zhou, Zhufa; Wang, Shumei

    2015-07-01

    Long-persistent luminescence /polymer (Ca2MgSi2O7:Eu2+, Dy3+/PLA) composite fibers have been fabricated via electrospinning method. The as-prepared one-dimensional fiber has been characterized by fluorescence microscope and distinct photographs have been obtained. The results show that the Ca2MgSi2O7:Eu2+, Dy3+ particles (12 wt%, size 200 nm) are uniformly dispersed in the PLA fibers (diameter 2.5 μm). It was found that the composite fibers have an emission band from 430 nm to 650 nm that peaks at 537 nm and 452 nm. Similarly, its phosphorescent emission spectra have similar features of luminescence (emission band from 430 nm to 650 nm that peaks at 537 nm and 452 nm). The decay curves of the composite fibers present a similar attenuate tendency with Ca2MgSi2O7:Eu2+, Dy3+ pure particles, but with lower intensity. The composite fiber has applications possibility in textile, display, optical detectors, indicator in the dark without electric energy which they never had before.

  18. High-Precision Pinpointing of Luminescent Targets in Encoder-Assisted Scanning Microscopy Allowing High-Speed Quantitative Analysis.

    PubMed

    Zheng, Xianlin; Lu, Yiqing; Zhao, Jiangbo; Zhang, Yuhai; Ren, Wei; Liu, Deming; Lu, Jie; Piper, James A; Leif, Robert C; Liu, Xiaogang; Jin, Dayong

    2016-01-19

    Compared with routine microscopy imaging of a few analytes at a time, rapid scanning through the whole sample area of a microscope slide to locate every single target object offers many advantages in terms of simplicity, speed, throughput, and potential for robust quantitative analysis. Existing techniques that accommodate solid-phase samples incorporating individual micrometer-sized targets generally rely on digital microscopy and image analysis, with intrinsically low throughput and reliability. Here, we report an advanced on-the-fly stage scanning method to achieve high-precision target location across the whole slide. By integrating X- and Y-axis linear encoders to a motorized stage as the virtual "grids" that provide real-time positional references, we demonstrate an orthogonal scanning automated microscopy (OSAM) technique which can search a coverslip area of 50 × 24 mm(2) in just 5.3 min and locate individual 15 μm lanthanide luminescent microspheres with standard deviations of 1.38 and 1.75 μm in X and Y directions. Alongside implementation of an autofocus unit that compensates the tilt of a slide in the Z-axis in real time, we increase the luminescence detection efficiency by 35% with an improved coefficient of variation. We demonstrate the capability of advanced OSAM for robust quantification of luminescence intensities and lifetimes for a variety of micrometer-scale luminescent targets, specifically single down-shifting and upconversion microspheres, crystalline microplates, and color-barcoded microrods, as well as quantitative suspension array assays of biotinylated-DNA functionalized upconversion nanoparticles. PMID:26669618

  19. Employing linear tetranuclear [Zn4(COO)4(OH)2] clusters as building subunits to construct a new Zn(II) coordination polymer with tunable luminescent properties

    NASA Astrophysics Data System (ADS)

    Li, Wu-Wu; Zhang, Zun-Ting

    2016-02-01

    A new Zn(II) coordination polymer, [Zn2(btc) (biimpy) (OH)]n (1 H3btc = 1,3,5-benzenetricarboxylic acid, biimpy = 2,6-bis(1-imdazoly)pyridine) has been successfully synthesized and characterized by elemental analysis, powder single crystal X-ray diffraction analyses. Compound 1 features a 3D framework employing linear tetranuclear [Zn4(COO)4(OH)2] cluster as building subunits. Topological analysis reveals it represents a (3,10)-connected structural topology by viewing btc3-, linear tetranuclear clusters and biimpy as 3-connected nodes, 10-connected nodes, linear linkers, respectively. Moreover, the thermal stability and luminescent property of compound 1 have been well investigated.

  20. High performance polymer tandem solar cell

    PubMed Central

    da Silva, Wilson Jose; Schneider, Fabio Kurt; Mohd Yusoff, Abd. Rashid bin; Jang, Jin

    2015-01-01

    A power conversion efficiency of 9.02% is obtained for a fully solution-processed polymer tandem solar cell, based on the diketopyrrolopyrrole unit polymer as a low bandgap photoactive material in the rear subcell, in conjunction with a new robust interconnecting layer. This interconnecting layer is optically transparent, electrically conductive, and physically strong, thus, the charges can be collected and recombined in the interconnecting layer under illumination, while the charge is generated and extracted under dark conditions. This indicates that careful interface engineering of the charge-carrier transport layer is a useful approach to further improve the performance of polymer tandem solar cells. PMID:26669577

  1. High performance polymer tandem solar cell

    NASA Astrophysics Data System (ADS)

    da Silva, Wilson Jose; Schneider, Fabio Kurt; Mohd Yusoff, Abd. Rashid Bin; Jang, Jin

    2015-12-01

    A power conversion efficiency of 9.02% is obtained for a fully solution-processed polymer tandem solar cell, based on the diketopyrrolopyrrole unit polymer as a low bandgap photoactive material in the rear subcell, in conjunction with a new robust interconnecting layer. This interconnecting layer is optically transparent, electrically conductive, and physically strong, thus, the charges can be collected and recombined in the interconnecting layer under illumination, while the charge is generated and extracted under dark conditions. This indicates that careful interface engineering of the charge-carrier transport layer is a useful approach to further improve the performance of polymer tandem solar cells.

  2. Preparation, cytotoxicity and in vivo bioimaging of highly luminescent water-soluble silicon quantum dots

    NASA Astrophysics Data System (ADS)

    Fan, Jing-Wun; Vankayala, Raviraj; Chang, Chien-Liang; Chang, Chia-Hua; Chiang, Chi-Shiun; Hwang, Kuo Chu

    2015-05-01

    Designing various inorganic nanomaterials that are cost effective, water soluble, optically photostable, highly fluorescent and biocompatible for bioimaging applications is a challenging task. Similar to semiconducting quantum dots (QDs), silicon QDs are another alternative and are highly fluorescent, but non-water soluble. Several surface modification strategies were adopted to make them water soluble. However, the photoluminescence of Si QDs was seriously quenched in the aqueous environment. In this report, highly luminescent, water-dispersible, blue- and green-emitting Si QDs were prepared with good photostability. In vitro studies in monocytes reveal that Si QDs exhibit good biocompatibility and excellent distribution throughout the cytoplasm region, along with the significant fraction translocated into the nucleus. The in vivo zebrafish studies also reveal that Si QDs can be evenly distributed in the yolk-sac region. Overall, our results demonstrate the applicability of water-soluble and highly fluorescent Si QDs as excellent in vitro and in vivo bioimaging probes.

  3. Luminescent and magnetic materials with a high content of Eu(3+)-EDTA complexes.

    PubMed

    Pires, G P; Costa, I F; Brito, H F; Faustino, W M; Teotonio, E E S

    2016-07-01

    Bifunctional optical magnetic materials with a high europium content have been prepared. Chelating groups were introduced on the Fe3O4 surface with organosilanes containing ethylenediaminetetraacetic acid (EDTA) derivatives, which were previously prepared via a reaction between EDTA-dianhydride and aminoalkoxysilane agents: 3-(trimethoxysilyl)propylamine (1N), N-[3(trimethoxysilyl)propyl]ethylenediamine (2N) and N(1)-(3-trimethoxysilylpropyl)diethylenetriamine) (3N). The first coordination sphere of Ln-EDTA complexes present on the modified surfaces of Fe3O4 particles was completed by addition of β-diketonate ligands (tta: thenoyltrifluoroacetone, dbm: dibenzoylmethane, bzac: benzoylacetone and acac: acetylacetone) in order to improve their luminescence properties. The materials were characterized by powder X-ray diffraction (XRD), vibrating sample magnetometry (VSM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and wavelength dispersive X-ray fluorescence (WDXRF) and Fourier-transform infrared (FT-IR) spectroscopy as well as by zeta potential measurements and luminescence spectroscopy. The hybrid materials exhibited intense red emission, which can be assigned to the 4f-4f transitions of the Eu(3+) ion, indicating an efficient intramolecular ligand-to-metal energy transfer. The experimental intensity parameters (Ω2 and Ω4), lifetimes (τ), as well as radiative (Arad) and non-radiative (Anrad) decay rates of the Eu(3+) ion were determined and discussed. The strategies used to obtain these materials may contribute to the development of several bifunctional systems for practical applications. PMID:27301580

  4. Highly Hydrophilic Luminescent Magnetic Mesoporous Carbon Nanospheres for Controlled Release of Anticancer Drug and Multimodal Imaging.

    PubMed

    Mohapatra, Sasmita; Rout, Smruti R; Das, Rahul K; Nayak, Santoshi; Ghosh, Sudip K

    2016-02-16

    Judicious combination of fluorescence and magnetic properties along with ample drug loading capacity and control release property remains a key challenge in the design of nanotheranostic agents. This paper reports the synthesis of highly hydrophilic optically traceable mesoporous carbon nanospheres which can sustain payloads of the anticancer drug doxorubicin and T2 contrast agent such as cobalt ferrite nanoparticles. The luminescent magnetic hybrid system has been prepared on a mesoporous silica template using a resorcinol-formaldehyde precursor. The mesoporous matrix shows controlled release of the aromatic drug doxorubicin due to disruption of supramolecular π-π interaction at acidic pH. The particles show MR contrast behavior by affecting the proton relaxation with transverse relaxivity (r2) 380 mM(-1) S(-1). The multicolored emission and upconversion luminescence property of our sample are advantageous in bioimaging. In vitro cell experiments shows that the hybrid nanoparticles are endocyted by the tumor cells through passive targeting. The pH-responsive release of doxorubicin presents chemotherapeutic inhibition of cell growth through induction of apoptosis. PMID:26794061

  5. Cold Flow as Versatile Approach for Stable and Highly Luminescent Quantum Dot-Salt Composites.

    PubMed

    Benad, Albrecht; Guhrenz, Chris; Bauer, Christoph; Eichler, Franziska; Adam, Marcus; Ziegler, Christoph; Gaponik, Nikolai; Eychmüller, Alexander

    2016-08-24

    Since the beginning of the 1980s, colloidally synthesized quantum dots (QDs) have been in the focus of interest due to their possible implementation for color conversion, luminescent light concentrators, and lasing. For all these applications, the QDs benefit from being embedded into a host matrix to ensure stability and usability. Many different host materials used for this purpose still have their individual shortcomings. Here, we present a universal, fast, and flexible approach for the direct incorporation of a wide range of QDs into inorganic ionic crystals using cold flow. The QD solution is mixed with a finely milled salt, followed by the removal of the solvent under vacuum. Under high pressure (GPa), the salt powder loaded with QDs transforms into transparent pellets. This effect is well-known for many inorganic salts (e.g., KCl, KBr, KI, NaCl, CsI, AgCl) from, e.g., sample preparation for IR spectroscopy. With this approach, we are able to obtain strongly luminescent QD-salt composites, have precise control over the loading, and provide a chemically robust matrix ensuring long-term stability of the embedded QDs. Furthermore, we show the photo-, chemical, and thermal stability of the composite materials and their use as color conversion layers for a white light-emitting diode (w-LED). The method presented can potentially be used for all kinds of nanoparticles synthesized in organic as well as in aqueous media. PMID:27482755

  6. Synthesis of highly luminescent mercaptosuccinic acid-coated CdSe nanocrystals under atmospheric conditions.

    PubMed

    Dong, Meiting; Xu, Jingyi; Liu, Shuxian; Zhou, Ying; Huang, Chaobiao

    2014-11-01

    Here we report a facile one-pot method for the preparation of high-quality CdSe nanocrystals (NCs) in aqueous solution under an air atmosphere. Compared with the traditional use of NaHSe or H2 Se, the more stable sodium selenite is utilized as the Se source for preparing highly luminescent CdSe nanocrystals. By using mercaptosuccinic acid (MSA) as the capping agent and borate-citrate acid as the buffering solution, CdSe nanocrystals with high quantum yield (up to 70%) have been synthesized conveniently. The influence of different experimental parameters, such as the pH of the precursor solution, the molar ratio of Cd(2+) to Na2 SeO3 and Cd(2+) to MSA on the CdSe nanocrystals, has been systematically investigated. The prepared CdSe NCs were spherical with a size of ~ 5 nm. PMID:24639040

  7. The luminescence of BaF{sub 2} nanoparticles upon high-energy excitation

    SciTech Connect

    Vistovskyy, V. V. Zhyshkovych, A. V.; Halyatkin, O. O.; Voloshinovskii, A. S.; Mitina, N. E.; Zaichenko, A. S.; Rodnyi, P. A.; Vasil'ev, A. N.; Gektin, A. V.

    2014-08-07

    The dependence of X-ray excited luminescence intensity on BaF{sub 2} nanoparticle size was studied. A sharp decrease of self-trapped exciton luminescence intensity was observed when the nanoparticle size is less than 80 nm. The main mechanism of the luminescence quenching is caused by the escape of electrons from the nanoparticles. Escape of electrons from nanoparticles is confirmed by the considerable increase of luminescence intensity of the polystyrene scintillator with embedded BaF{sub 2} nanoparticles comparing with pure polystyrene scintillator.

  8. NK sensitivity of neuroblastoma cells determined by a highly sensitive coupled luminescent method

    SciTech Connect

    Ogbomo, Henry; Hahn, Anke; Geiler, Janina; Michaelis, Martin; Doerr, Hans Wilhelm; Cinatl, Jindrich . E-mail: Cinatl@em.uni-frankfurt.de

    2006-01-06

    The measurement of natural killer (NK) cells toxicity against tumor or virus-infected cells especially in cases with small blood samples requires highly sensitive methods. Here, a coupled luminescent method (CLM) based on glyceraldehyde-3-phosphate dehydrogenase release from injured target cells was used to evaluate the cytotoxicity of interleukin-2 activated NK cells against neuroblastoma cell lines. In contrast to most other methods, CLM does not require the pretreatment of target cells with labeling substances which could be toxic or radioactive. The effective killing of tumor cells was achieved by low effector/target ratios ranging from 0.5:1 to 4:1. CLM provides highly sensitive, safe, and fast procedure for measurement of NK cell activity with small blood samples such as those obtained from pediatric patients.

  9. Conducting polymer for high power ultracapacitor

    DOEpatents

    Shi, Steven Z.; Gottesfeld, Shimshon

    2002-01-01

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

  10. Exploring the origin of high optical absorption in conjugated polymers.

    PubMed

    Vezie, Michelle S; Few, Sheridan; Meager, Iain; Pieridou, Galatia; Dörling, Bernhard; Ashraf, Raja Shahid; Goñi, Alejandro R; Bronstein, Hugo; McCulloch, Iain; Hayes, Sophia C; Campoy-Quiles, Mariano; Nelson, Jenny

    2016-07-01

    The specific optical absorption of an organic semiconductor is critical to the performance of organic optoelectronic devices. For example, higher light-harvesting efficiency can lead to higher photocurrent in solar cells that are limited by sub-optimal electrical transport. Here, we compare over 40 conjugated polymers, and find that many different chemical structures share an apparent maximum in their extinction coefficients. However, a diketopyrrolopyrrole-thienothiophene copolymer shows remarkably high optical absorption at relatively low photon energies. By investigating its backbone structure and conformation with measurements and quantum chemical calculations, we find that the high optical absorption can be explained by the high persistence length of the polymer. Accordingly, we demonstrate high absorption in other polymers with high theoretical persistence length. Visible light harvesting may be enhanced in other conjugated polymers through judicious design of the structure. PMID:27183327

  11. High-efficiency solution processable polymer photovoltaic cells by self-organization of polymer blends

    NASA Astrophysics Data System (ADS)

    Li, Gang; Shrotriya, Vishal; Huang, Jinsong; Yao, Yan; Moriarty, Tom; Emery, Keith; Yang, Yang

    2005-11-01

    Converting solar energy into electricity provides a much-needed solution to the energy crisis the world is facing today. Polymer solar cells have shown potential to harness solar energy in a cost-effective way. Significant efforts are underway to improve their efficiency to the level of practical applications. Here, we report highly efficient polymer solar cells based on a bulk heterojunction of polymer poly(3-hexylthiophene) and methanofullerene. Controlling the active layer growth rate results in an increased hole mobility and balanced charge transport. Together with increased absorption in the active layer, this results in much-improved device performance, particularly in external quantum efficiency. The power-conversion efficiency of 4.4% achieved here is the highest published so far for polymer-based solar cells. The solution process involved ensures that the fabrication cost remains low and the processing is simple. The high efficiency achieved in this work brings these devices one step closer to commercialization.

  12. Transformation of crystalline starch nanoparticles into highly luminescent carbon nanodots: Toxicity studies and their applications.

    PubMed

    Sonthanasamy, Regina Sisika A; Ahmad, Wan Yaacob Wan; Fazry, Shazrul; Hassan, Nurul I; Lazim, Azwan Mat

    2016-02-10

    Being abundant in many tropical part of the world, Dioscorea sp. as food is limited due to its toxicity. However polysaccharides derive from these tubers could be important for other applications. Here we developed a Highly Luminescent Carbon Nanodots (C-dots) via acid hydrolysis of Gadong starch (GS). The hydrolysis rate of GS increased from 49% to 86% within 7 days while the X-ray diffraction showed the native GS particle is a C-crystalline type. The GS particles were either round or oval with diameters ranging from 50-90 nm. Further acid dehydration and surface oxidation reduced the size of GS nanoparticles to 6-25 nm. The C-dots produced a fluorescent emission at wavelength 441 nm. Toxicity tests demonstrate that zebrafish embryo were able to tolerate the C-dots for 48 h after exposure. This study has successfully demonstrated a novel approach of converting GS into excellent fluorescent C-dot. PMID:26686155

  13. Luminescence of mesoporous silicon powders treated by high-pressure water vapor annealing

    NASA Astrophysics Data System (ADS)

    Gelloz, Bernard; Loni, Armando; Canham, Leigh; Koshida, Nobuyoshi

    2012-07-01

    We have studied the photoluminescence of nanocrystalline silicon microparticle powders fabricated by fragmentation of PSi membranes. Several porosities were studied. Some powders have been subjected to further chemical etching in HF in order to reduce the size of the silicon skeleton and reach quantum sizes. High-pressure water vapor annealing was then used to enhance both the luminescence efficiency and stability. Two visible emission bands were observed. A red band characteristic of the emission of Si nanocrystals and a blue band related to localized centers in oxidized powders. The blue band included a long-lived component, with a lifetime exceeding 1 sec. Both emission bands depended strongly on the PSi initial porosity. The colors of the processed powders were tunable from brown to off-white, depending on the level of oxidation. The surface area and pore volume of some powders were also measured and discussed. The targeted applications are in cosmetics and medicine.

  14. Luminescence of black silicon fabricated by high-repetition rate femtosecond laser pulses

    SciTech Connect

    Chen Tao; Si Jinhai; Hou Xun; Kanehira, Shingo; Miura, Kiyotaka; Hirao, Kazuyuki

    2011-10-01

    We studied the photoluminescence (PL) from black silicon that was fabricated using an 800 nm, 250 kHz femtosecond laser in air. By changing the scan velocity and the fluence of the femtosecond laser, the formation of the PL band between the orange (600 nm) and red bands (near 680 nm) could be controlled. The red band PL from the photoinduced microstructures on the black silicon was observed even without annealing due to the thermal accumulation of high-repetition rate femtosecond laser pulses. The orange band PL was easily quenched under 532 nm cw laser irradiation, whereas the red band PL was more stable; this can be attributed to ''defect luminescence'' and ''quantum confinement'', respectively.

  15. Two-photon luminescence thermometry: towards 3D high-resolution thermal imaging of waveguides.

    PubMed

    He, Ruiyun; Vázquez de Aldana, Javier Rodríguez; Pedrola, Ginés Lifante; Chen, Feng; Jaque, Daniel

    2016-07-11

    We report on the use of the Erbium-based luminescence thermometry to realize high resolution, three dimensional thermal imaging of optical waveguides. Proof of concept is demonstrated in a 980-nm laser pumped ultrafast laser inscribed waveguide in Er:Yb phosphate glass. Multi-photon microscopy images revealed the existence of well confined intra-waveguide temperature increments as large as 200 °C for moderate 980-nm pump powers of 120 mW. Numerical simulations and experimental data reveal that thermal loading can be substantially reduced if pump events are separated more than the characteristic thermal time that for the waveguides investigated is in the ms time scale. PMID:27410882

  16. Simulated space environmental effects on some experimental high performance polymers

    NASA Technical Reports Server (NTRS)

    Connell, John W.

    1993-01-01

    High performance polymers for potential space applications were evaluated under simulated space environmental conditions. Experimental resins from blends of acetylene terminated materials, poly(arylene ether)s and low color polyimides were exposed to high energy electron and ultraviolet radiation in an attempt to simulate space environmental effects. Thin films, neat resin moldings, and carbon fiber reinforced composites were exposed, and the effect on certain polymer properties were determined. Recent research involving the effects of various radiation exposures on the physical, optical, and mechanical properties of several experimental polymer systems is reviewed.

  17. Transparent composite electrode for high-efficiency polymer LEDs

    NASA Astrophysics Data System (ADS)

    Li, Lu; Yu, Zhibin; Liang, Jiajie; Chang, Chia-Hao; Hu, Weili; Pei, Qibing

    2012-09-01

    Polymer composite electrodes based on silver nanowires or carbon nanotubes have been prepared with transparency and surface conductivity approaching those of ITO/glass and better than ITO/PET. The conductive surface has an average roughness less than 10 nm, better than ITO/glass. Depending on the polymer matrix selected, the composite electrodes can be made rigid, flexible like polycarbonate, or stretchable like a rubber. Various polymer light emitting diodes,light emitting electrochemical cells and polymer solar cells have been fabricated using the composite electrode as anode, exhibiting electroluminescent efficiencies generally higher than control devices fabricated on ITO/glass. These polymer light emitting devices are all highly flexible and can be bent to less than 3 mm radius without loss of performance. With further modification of the composite electrodes, we have also demonstrated stretchable OLEDs wherein the emissive area can be elongated by as much as 50%.

  18. Low-magnesium uranium-calcite with high degree of crystallinity and gigantic luminescence emission.

    PubMed

    Valle-Fuentes, Francisco-Jose; Garcia-Guinea, Javier; Cremades, Ana; Correcher, Virgilio; Sanchez-Moral, Sergio; Gonzalez-Martin, Rafael; Sanchez-Muñoz, Luis; Lopez-Arce, Paula

    2007-01-01

    Cabrera (Madrid) low-Mg calcites exhibit: (i) an unusual twofold elevation in X-ray diffraction pattern intensity; (ii) a 60-fold elevation of luminescence emission, compared to six common natural calcites selected for comparison purposes; (iii) a natural relatively high radiation level of circa 200 nSvh(-1) not detected in 1300 other calcites from the Natural History Museum of Madrid. Calcites were analysed by the X-ray diffraction powder method (XRD), cathodo-luminescence spectroscopy in scanning electron microscopy (CL-SEM), thermoluminescence (TL), differential thermal analysis (DTA), X-ray fluorescence spectrometry (XRF) and particle size distribution (PSD). The Cabrera calcite study shows: (i) helicoidally distributed steps along the (0001) orientation; (ii) protuberance defects onto the (0001) surface, observed by SEM; (iii) XRF chemical contents of 0.03% MgO, 0.013% of Y(2)O(3), and 0.022% of U(3)O(8), with accessory amounts of rare earth elements (REE); (iv) DTA dissociation temperature of 879 degrees C; (v) TL maxima peaks at 233 and 297 degrees C whose areas are 60 times compared to other calcites; (vi) spectra CL-SEM bands at 2.0 and 3.4 eV in the classic structure of Mn(2+) activators; (vii) a twofold XRD pattern explained given that sample is a low-Mg calcite. The huge TL and CL emissions of the Cabrera calcite sample must be linked with the uranyl group presence. This intense XRD pattern in low-Mg calcites could bring into being analytical errors. PMID:17011199

  19. Ag-SiO₂-Er₂O₃ nanocomposites: highly effective upconversion luminescence at high power excitation and high temperature.

    PubMed

    Xu, Wen; Min, Xiaolei; Chen, Xu; Zhu, Yongsheng; Zhou, Pingwei; Cui, Shaobo; Xu, Sai; Tao, Li; Song, Hongwei

    2014-01-01

    Rare Earth (RE) activated upconversion phosphors (UCPs), have demonstrated significant application potentials in some front fields, including solar energy conversion and bio-application. However, some bottleneck problems should be overcame, such as the lower upconversion efficiency, narrower excitation band, concentration-quenching and temperature-quenching. To solve these problems, the Ag-SiO2-Er2O3 nanocomposites were fabricated, in which the upconversion luminescence (UCL) of Er2O3 was white broadband. Through the interaction of Er2O3 with surface plasmon (SP) of silver nanoparticles (SNPs), the threshold power for generating broadbands was suppressed largely in contrast to the Er2O3 nanoparticles (NPs), while the UCL brightness was enhanced remarkably, ranging from several to 10(4) times, which strongly depended on the power density of excitation light. At excitation power density of 1.50 W/mm(2) of 980 nm light, the UCL intensity of Ag-SiO2-Er2O3 is 40-folds than the well-known NaYF4:Yb(3+),Er(3+) commercial powders. And more, it is also interesting to observe that the composites demonstrate two excitation bands extending of 780-980 nm, highly improved UCL with elevated temperature and excitation power density. The UCL mechanism related to UCL enhancement was carefully studied. PMID:24867159

  20. A simple strategy for synthesizing highly luminescent carbon nanodots and application as effective down-shifting layers.

    PubMed

    Han, Xugen; Zhong, Sihua; Pan, Wei; Shen, Wenzhong

    2015-02-13

    We propose a novel strategy to prepare highly luminescent carbon nanodots (C-dots) by employing a hydrothermal method with citric acid as the carbon source and ethylenediamine as the nitrogen source, together with adding moderate ammonia water (AW) to achieve both appropriate inner structure and excellent N passivation. The effect of pH value and AW amount on the luminescence properties has been thoroughly investigated. The photoluminescence quantum yield of the resultant C-dots reaches as high as 84.8%, which is of 10.56% higher than that of the C-dots synthesized in the absence of AW in the reaction precursors. We have further combined the highest luminescent C-dots with polyvinyl alcohol to form luminescent down-shifting layers on silicon nanowire solar cells. An effective enhancement of short-circuit current density has been realized and the contribution of the down-shifting has been extracted quantitatively from the deterioration of surface reflectance and the gain of the optical absorption redistribution by means of a theoretical model on external quantum efficiency analysis. PMID:25611852

  1. A simple strategy for synthesizing highly luminescent carbon nanodots and application as effective down-shifting layers

    NASA Astrophysics Data System (ADS)

    Han, Xugen; Zhong, Sihua; Pan, Wei; Shen, Wenzhong

    2015-02-01

    We propose a novel strategy to prepare highly luminescent carbon nanodots (C-dots) by employing a hydrothermal method with citric acid as the carbon source and ethylenediamine as the nitrogen source, together with adding moderate ammonia water (AW) to achieve both appropriate inner structure and excellent N passivation. The effect of pH value and AW amount on the luminescence properties has been thoroughly investigated. The photoluminescence quantum yield of the resultant C-dots reaches as high as 84.8%, which is of 10.56% higher than that of the C-dots synthesized in the absence of AW in the reaction precursors. We have further combined the highest luminescent C-dots with polyvinyl alcohol to form luminescent down-shifting layers on silicon nanowire solar cells. An effective enhancement of short-circuit current density has been realized and the contribution of the down-shifting has been extracted quantitatively from the deterioration of surface reflectance and the gain of the optical absorption redistribution by means of a theoretical model on external quantum efficiency analysis.

  2. Three-Photon Luminescence of Gold Nanorods and Its Applications for High Contrast Tissue and Deep In Vivo Brain Imaging

    PubMed Central

    Wang, Shaowei; Xi, Wang; Cai, Fuhong; Zhao, Xinyuan; Xu, Zhengping; Qian, Jun; He, Sailing

    2015-01-01

    Gold nanoparticles can be used as contrast agents for bio-imaging applications. Here we studied multi-photon luminescence (MPL) of gold nanorods (GNRs), under the excitation of femtosecond (fs) lasers. GNRs functionalized with polyethylene glycol (PEG) molecules have high chemical and optical stability, and can be used as multi-photon luminescent nanoprobes for deep in vivo imaging of live animals. We have found that the depth of in vivo imaging is dependent upon the transmission and focal capability of the excitation light interacting with the GNRs. Our study focused on the comparison of MPL from GNRs with two different aspect ratios, as well as their ex vivo and in vivo imaging effects under 760 nm and 1000 nm excitation, respectively. Both of these wavelengths were located at an optically transparent window of biological tissue (700-1000 nm). PEGylated GNRs, which were intravenously injected into mice via the tail vein and accumulated in major organs and tumor tissue, showed high image contrast due to distinct three-photon luminescence (3PL) signals upon irradiation of a 1000 nm fs laser. Concerning in vivo mouse brain imaging, the 3PL imaging depth of GNRs under 1000 nm fs excitation could reach 600 μm, which was approximately 170 μm deeper than the two-photon luminescence (2PL) imaging depth of GNRs with a fs excitation of 760 nm. PMID:25553113

  3. Polymer concrete pipe for high-temperature corrosive environments

    SciTech Connect

    Kukacka, L.E.; Schroeder, J.E.

    1981-01-01

    Polymer concrete is a composite material which has strength and durability characteristics greatly superior to those of Portland cement concrete and better durability than steel. Polymer concrete has been successfully tested in brine, flashing brine and steam at temperatures up to 260/sup 0/C. Exposures were as long as 960 days. Glass filament wound polymer concrete pipe was developed with excellent strength, low weight, and a cost comparable to or less than schedule 40 steel. Connections can be made with slip joints for low pressure applications and flanged joints for high pressure applications.

  4. High Performance Polymers and Composites (HiPPAC) Center

    NASA Technical Reports Server (NTRS)

    Mintz, Eric A.; Veazie, David

    2005-01-01

    NASA University Research Centers funding has allowed Clark Atlanta University (CAU) to establish a High Performance Polymers and Composites (HiPPAC) Research Center. Clark Atlanta University, through the HiPPAC Center has consolidated and expanded its polymer and composite research capabilities through the development of research efforts in: (1) Synthesis and characterization of polymeric NLO, photorefractive, and piezoelectric materials; (2) Characterization and engineering applications of induced strain smart materials; (3) Processable polyimides and additives to enhance polyimide processing for composite applications; (4) Fabrication and mechanical characterization of polymer based composites.

  5. Significantly Increasing the Ductility of High Performance Polymer Semiconductors through Polymer Blending.

    PubMed

    Scott, Joshua I; Xue, Xiao; Wang, Ming; Kline, R Joseph; Hoffman, Benjamin C; Dougherty, Daniel; Zhou, Chuanzhen; Bazan, Guillermo; O'Connor, Brendan T

    2016-06-01

    Polymer semiconductors based on donor-acceptor monomers have recently resulted in significant gains in field effect mobility in organic thin film transistors (OTFTs). These polymers incorporate fused aromatic rings and have been designed to have stiff planar backbones, resulting in strong intermolecular interactions, which subsequently result in stiff and brittle films. The complex synthesis typically required for these materials may also result in increased production costs. Thus, the development of methods to improve mechanical plasticity while lowering material consumption during fabrication will significantly improve opportunities for adoption in flexible and stretchable electronics. To achieve these goals, we consider blending a brittle donor-acceptor polymer, poly[4-(4,4-dihexadecyl-4H-cyclopenta[1,2-b:5,4-b']dithiophen-2-yl)-alt-[1,2,5]thiadiazolo[3,4-c]pyridine] (PCDTPT), with ductile poly(3-hexylthiophene). We found that the ductility of the blend films is significantly improved compared to that of neat PCDTPT films, and when the blend film is employed in an OTFT, the performance is largely maintained. The ability to maintain charge transport character is due to vertical segregation within the blend, while the improved ductility is due to intermixing of the polymers throughout the film thickness. Importantly, the application of large strains to the ductile films is shown to orient both polymers, which further increases charge carrier mobility. These results highlight a processing approach to achieve high performance polymer OTFTs that are electrically and mechanically optimized. PMID:27200458

  6. High-efficiency upconversion luminescent sensing and bioimaging of Hg(II) by chromophoric ruthenium complex-assembled nanophosphors.

    PubMed

    Liu, Qian; Peng, Juanjuan; Sun, Lining; Li, Fuyou

    2011-10-25

    A chromophoric ruthenium complex-assembled nanophosphor (N719-UCNPs) was achieved as a highly selective water-soluble probe for upconversion luminescence sensing and bioimaging of intracellular mercury ions. The prepared nanophosphors were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray analysis (EDXA), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). Further application of N719-UCNPs in sensing Hg(2+) was confirmed by optical titration experiment and upconversion luminescence live cell imaging. Using the ratiometric upconversion luminescence as a detection signal, the detection limit of Hg(2+) for this nanoprobe in water was down to 1.95 ppb, lower than the maximum level (2 ppb) of Hg(2+) in drinking water set by the United States EPA. Importantly, the nanoprobe N719-UCNPs has been shown to be capable of monitoring changes in the distribution of Hg(2+) in living cells by upconversion luminescence bioimaging. PMID:21899309

  7. Highly efficient large-area colourless luminescent solar concentrators using heavy-metal-free colloidal quantum dots.

    PubMed

    Meinardi, Francesco; McDaniel, Hunter; Carulli, Francesco; Colombo, Annalisa; Velizhanin, Kirill A; Makarov, Nikolay S; Simonutti, Roberto; Klimov, Victor I; Brovelli, Sergio

    2015-10-01

    Luminescent solar concentrators serving as semitransparent photovoltaic windows could become an important element in net zero energy consumption buildings of the future. Colloidal quantum dots are promising materials for luminescent solar concentrators as they can be engineered to provide the large Stokes shift necessary for suppressing reabsorption losses in large-area devices. Existing Stokes-shift-engineered quantum dots allow for only partial coverage of the solar spectrum, which limits their light-harvesting ability and leads to colouring of the luminescent solar concentrators, complicating their use in architecture. Here, we use quantum dots of ternary I-III-VI2 semiconductors to realize the first large-area quantum dot-luminescent solar concentrators free of toxic elements, with reduced reabsorption and extended coverage of the solar spectrum. By incorporating CuInSexS2-x quantum dots into photo-polymerized poly(lauryl methacrylate), we obtain freestanding, colourless slabs that introduce no distortion to perceived colours and are thus well suited for the realization of photovoltaic windows. Thanks to the suppressed reabsorption and high emission efficiencies of the quantum dots, we achieve an optical power efficiency of 3.2%. Ultrafast spectroscopy studies suggest that the Stokes-shifted emission involves a conduction-band electron and a hole residing in an intragap state associated with a native defect. PMID:26301902

  8. Highly efficient large-area colourless luminescent solar concentrators using heavy-metal-free colloidal quantum dots

    NASA Astrophysics Data System (ADS)

    Meinardi, Francesco; McDaniel, Hunter; Carulli, Francesco; Colombo, Annalisa; Velizhanin, Kirill A.; Makarov, Nikolay S.; Simonutti, Roberto; Klimov, Victor I.; Brovelli, Sergio

    2015-10-01

    Luminescent solar concentrators serving as semitransparent photovoltaic windows could become an important element in net zero energy consumption buildings of the future. Colloidal quantum dots are promising materials for luminescent solar concentrators as they can be engineered to provide the large Stokes shift necessary for suppressing reabsorption losses in large-area devices. Existing Stokes-shift-engineered quantum dots allow for only partial coverage of the solar spectrum, which limits their light-harvesting ability and leads to colouring of the luminescent solar concentrators, complicating their use in architecture. Here, we use quantum dots of ternary I-III-VI2 semiconductors to realize the first large-area quantum dot-luminescent solar concentrators free of toxic elements, with reduced reabsorption and extended coverage of the solar spectrum. By incorporating CuInSexS2-x quantum dots into photo-polymerized poly(lauryl methacrylate), we obtain freestanding, colourless slabs that introduce no distortion to perceived colours and are thus well suited for the realization of photovoltaic windows. Thanks to the suppressed reabsorption and high emission efficiencies of the quantum dots, we achieve an optical power efficiency of 3.2%. Ultrafast spectroscopy studies suggest that the Stokes-shifted emission involves a conduction-band electron and a hole residing in an intragap state associated with a native defect.

  9. Flexible high-temperature dielectric materials from polymer nanocomposites

    NASA Astrophysics Data System (ADS)

    Li, Qi; Chen, Lei; Gadinski, Matthew R.; Zhang, Shihai; Zhang, Guangzu; Li, Haoyu; Haque, Aman; Chen, Long-Qing; Jackson, Tom; Wang, Qing

    2015-07-01

    Dielectric materials, which store energy electrostatically, are ubiquitous in advanced electronics and electric power systems. Compared to their ceramic counterparts, polymer dielectrics have higher breakdown strengths and greater reliability, are scalable, lightweight and can be shaped into intricate configurations, and are therefore an ideal choice for many power electronics, power conditioning, and pulsed power applications. However, polymer dielectrics are limited to relatively low working temperatures, and thus fail to meet the rising demand for electricity under the extreme conditions present in applications such as hybrid and electric vehicles, aerospace power electronics, and underground oil and gas exploration. Here we describe crosslinked polymer nanocomposites that contain boron nitride nanosheets, the dielectric properties of which are stable over a broad temperature and frequency range. The nanocomposites have outstanding high-voltage capacitive energy storage capabilities at record temperatures (a Weibull breakdown strength of 403 megavolts per metre and a discharged energy density of 1.8 joules per cubic centimetre at 250 degrees Celsius). Their electrical conduction is several orders of magnitude lower than that of existing polymers and their high operating temperatures are attributed to greatly improved thermal conductivity, owing to the presence of the boron nitride nanosheets, which improve heat dissipation compared to pristine polymers (which are inherently susceptible to thermal runaway). Moreover, the polymer nanocomposites are lightweight, photopatternable and mechanically flexible, and have been demonstrated to preserve excellent dielectric and capacitive performance after intensive bending cycles. These findings enable broader applications of organic materials in high-temperature electronics and energy storage devices.

  10. Flexible high-temperature dielectric materials from polymer nanocomposites.

    PubMed

    Li, Qi; Chen, Lei; Gadinski, Matthew R; Zhang, Shihai; Zhang, Guangzu; Li, Haoyu; Haque, Aman; Chen, Long-Qing; Jackson, Tom; Wang, Qing

    2015-07-30

    Dielectric materials, which store energy electrostatically, are ubiquitous in advanced electronics and electric power systems. Compared to their ceramic counterparts, polymer dielectrics have higher breakdown strengths and greater reliability, are scalable, lightweight and can be shaped into intricate configurations, and are therefore an ideal choice for many power electronics, power conditioning, and pulsed power applications. However, polymer dielectrics are limited to relatively low working temperatures, and thus fail to meet the rising demand for electricity under the extreme conditions present in applications such as hybrid and electric vehicles, aerospace power electronics, and underground oil and gas exploration. Here we describe crosslinked polymer nanocomposites that contain boron nitride nanosheets, the dielectric properties of which are stable over a broad temperature and frequency range. The nanocomposites have outstanding high-voltage capacitive energy storage capabilities at record temperatures (a Weibull breakdown strength of 403 megavolts per metre and a discharged energy density of 1.8 joules per cubic centimetre at 250 degrees Celsius). Their electrical conduction is several orders of magnitude lower than that of existing polymers and their high operating temperatures are attributed to greatly improved thermal conductivity, owing to the presence of the boron nitride nanosheets, which improve heat dissipation compared to pristine polymers (which are inherently susceptible to thermal runaway). Moreover, the polymer nanocomposites are lightweight, photopatternable and mechanically flexible, and have been demonstrated to preserve excellent dielectric and capacitive performance after intensive bending cycles. These findings enable broader applications of organic materials in high-temperature electronics and energy storage devices. PMID:26223625

  11. Synthesis of Composition Tunable and Highly Luminescent Cesium Lead Halide Nanowires through Anion-Exchange Reactions.

    PubMed

    Zhang, Dandan; Yang, Yiming; Bekenstein, Yehonadav; Yu, Yi; Gibson, Natalie A; Wong, Andrew B; Eaton, Samuel W; Kornienko, Nikolay; Kong, Qiao; Lai, Minliang; Alivisatos, A Paul; Leone, Stephen R; Yang, Peidong

    2016-06-15

    Here, we demonstrate the successful synthesis of brightly emitting colloidal cesium lead halide (CsPbX3, X = Cl, Br, I) nanowires (NWs) with uniform diameters and tunable compositions. By using highly monodisperse CsPbBr3 NWs as templates, the NW composition can be independently controlled through anion-exchange reactions. CsPbX3 alloy NWs with a wide range of alloy compositions can be achieved with well-preserved morphology and crystal structure. The NWs are highly luminescent with photoluminescence quantum yields (PLQY) ranging from 20% to 80%. The bright photoluminescence can be tuned over nearly the entire visible spectrum. The high PLQYs together with charge transport measurements exemplify the efficient alloying of the anionic sublattice in a one-dimensional CsPbX3 system. The wires increased functionality in the form of fast photoresponse rates and the low defect density suggest CsPbX3 NWs as prospective materials for optoelectronic applications. PMID:27213511

  12. Metrology challenges for high-rate nanomanufacturing of polymer structures

    NASA Astrophysics Data System (ADS)

    Mead, Joey; Barry, Carol; Busnaina, Ahmed; Isaacs, Jacqueline

    2012-10-01

    The transfer of nanoscience accomplishments into commercial products is hindered by the lack of understanding of barriers to nanoscale manufacturing. We have developed a number of nanomanufacturing processes that leverage available high-rate plastics fabrication technologies. These processes include directed assembly of a variety of nanoelements, such as nanoparticles and nanotubes, which are then transferred onto a polymer substrate for the fabrication of conformal/flexible electronic materials, among other applications. These assembly processes utilize both electric fields and/or chemical functionalization. Conducting polymers and carbon nanotubes have been successfully transferred to a polymer substrate in times less than 5 minutes, which is commercially relevant and can be utilized in a continuous (reel to reel/roll to roll) process. Other processes include continuous high volume mixing of nanoelements (CNTs, etc) into polymers, multi-layer extrusion and 3D injection molding of polymer structures. These nanomanufacturing processes can be used for wide range of applications, including EMI shielding, flexible electronics, structural materials, and novel sensors (specifically for chem/bio detection). Current techniques to characterize the quality and efficacy of the processes are quite slow. Moreover, the instrumentation and metrology needs for these manufacturing processes are varied and challenging. Novel, rapid, in-line metrology to enable the commercialization of these processes is critically needed. This talk will explore the necessary measurement needs for polymer based nanomanufacturing processes for both step and continuous (reel to reel/roll to roll) processes.

  13. Atomic structure of luminescent centers in high-efficiency Ce-doped w-AlN single crystal.

    PubMed

    Ishikawa, Ryo; Lupini, Andrew R; Oba, Fumiyasu; Findlay, Scott D; Shibata, Naoya; Taniguchi, Takashi; Watanabe, Kenji; Hayashi, Hiroyuki; Sakai, Toshifumi; Tanaka, Isao; Ikuhara, Yuichi; Pennycook, Stephen J

    2014-01-01

    Rare-earth doped wurtzite-type aluminum nitride (w-AlN) has great potential for high-efficiency electroluminescent applications over a wide wavelength range. However, because of their large atomic size, it has been difficult to stably dope individual rare-earth atoms into the w-AlN host lattice. Here we use a reactive flux method under high pressure and high temperature to obtain cerium (Ce) doped w-AlN single crystals with pink-colored luminescence. In order to elucidate the atomic structure of the luminescent centers, we directly observe individual Ce dopants in w-AlN using annular dark-field scanning transmission electron microscopy. We find that Ce is incorporated as single, isolated atoms inside the w-AlN lattice occupying Al substitutional sites. This new synthesis method represents a new alternative strategy for doping size-mismatched functional atoms into wide band-gap materials. PMID:24445335

  14. Atomic Structure of Luminescent Centers in High-Efficiency Ce-doped w-AlN Single Crystal

    PubMed Central

    Ishikawa, Ryo; Lupini, Andrew R.; Oba, Fumiyasu; Findlay, Scott D.; Shibata, Naoya; Taniguchi, Takashi; Watanabe, Kenji; Hayashi, Hiroyuki; Sakai, Toshifumi; Tanaka, Isao; Ikuhara, Yuichi; Pennycook, Stephen J.

    2014-01-01

    Rare-earth doped wurtzite-type aluminum nitride (w-AlN) has great potential for high-efficiency electroluminescent applications over a wide wavelength range. However, because of their large atomic size, it has been difficult to stably dope individual rare-earth atoms into the w-AlN host lattice. Here we use a reactive flux method under high pressure and high temperature to obtain cerium (Ce) doped w-AlN single crystals with pink-colored luminescence. In order to elucidate the atomic structure of the luminescent centers, we directly observe individual Ce dopants in w-AlN using annular dark-field scanning transmission electron microscopy. We find that Ce is incorporated as single, isolated atoms inside the w-AlN lattice occupying Al substitutional sites. This new synthesis method represents a new alternative strategy for doping size-mismatched functional atoms into wide band-gap materials. PMID:24445335

  15. Thermal Protective Coating for High Temperature Polymer Composites

    NASA Technical Reports Server (NTRS)

    Barron, Andrew R.

    1999-01-01

    The central theme of this research is the application of carboxylate-alumoxane nanoparticles as precursors to thermally protective coatings for high temperature polymer composites. In addition, we will investigate the application of carboxylate-alumoxane nanoparticle as a component to polymer composites. The objective of this research was the high temperature protection of polymer composites via novel chemistry. The significance of this research is the development of a low cost and highly flexible synthetic methodology, with a compatible processing technique, for the fabrication of high temperature polymer composites. We proposed to accomplish this broad goal through the use of a class of ceramic precursor material, alumoxanes. Alumoxanes are nano-particles with a boehmite-like structure and an organic periphery. The technical goals of this program are to prepare and evaluate water soluble carboxylate-alumoxane for the preparation of ceramic coatings on polymer substrates. Our proposed approach is attractive since proof of concept has been demonstrated under the NRA 96-LeRC-1 Technology for Advanced High Temperature Gas Turbine Engines, HITEMP Program. For example, carbon and Kevlar(tm) fibers and matting have been successfully coated with ceramic thermally protective layers.

  16. Luminescent coordination polymers for the VIS and NIR range constituting LnCl3 and 1,2-bis(4-pyridyl)ethane.

    PubMed

    Dannenbauer, N; Matthes, P R; Müller-Buschbaum, K

    2016-04-12

    A series of 14 lanthanide containing coordination polymers LnCl3 with 1,2-bis(4-pyridyl)ethane (bpe) was synthesized from either thiazole or pyridine. Depending on the ligand content, a structural diversity from 3D-frameworks [LnCl3(bpe)2]·thz, Ln = Ce-Lu, to 1D-strands [La2Cl6(bpe)2(thz)6] and [LnCl3(bpe)(py)2]·(bpe/py), Ln = Gd, Er, was obtained and characterized by X-ray single crystal diffraction, powder diffraction, differential thermal analysis and thermogravimetry (DTA/TG), IR-spectroscopy and photoluminescence spectroscopy. The compounds exhibit a variety of luminescence properties and different phenomena. This includes ligand centred fluorescence, metal-centred 5d-4f/4f-4f emission in the visible and the NIR range, antenna effects via Dexter and Förster energy transfer mechanisms, excitation dependent emission with a correlating shift of the chromaticity coordinates and inner filter effects by combined re-absorption/emission. PMID:26956557

  17. Crystal structure, infrared spectra and luminescence of a 1D Cd coordination polymer with 4-nitrophthalic acid and 1,10-phenanthroline monohydrate ligands

    NASA Astrophysics Data System (ADS)

    Han, Li-Juan; Kong, Ya-Jie; Sheng, Ning

    2015-01-01

    A new one-dimensional (1D) coordination polymer, [Cd(NPTA)(1,10-phen)(H2O)] n ( 1) (H2NPTA = 4-nitrophthalic acid; 1,10-phen = 1,10-phenanthroline monohydrate), has been synthesized under hydrothermal conditions and characterized by elemental analysis, single-crystal X-ray diffraction, solid state emission spectra, FT-IR spectra, and thermogravimetric analyses. The compound belongs to triclinic system with space group , and exhibits a one-dimensional linear chain. Each Cd with a strongly distorted octahedral coordination geometry is six-coordinated by two N atoms from one 1,10-phenanthroline ligand, three O atoms from two carboxylate groups of two different NPTA2- ligands and one O atoms from lattice water. Layer supramolecular architecture is formed by medium π-π stacking interactions between two neighboring phenanthroline rings from two independent linear chains. Studies on luminescent property of 1 exhibit the solid state emission originating from an intra ligand π → π* transition of NPTA2- ligand.

  18. Two three-dimensional coordination polymers of lead(II) with iminodiacetate and naphthalene-dicarboxylate anions: Synthesis, characterization and luminescence behavior

    SciTech Connect

    Hazari, Debdoot; Jana, Swapan Kumar; Fleck, Michel; Zangrando, Ennio; Dalai, Sudipta

    2014-11-15

    Two lead(II) compounds [Pb{sub 3}(idiac){sub 3}(phen){sub 2}(H{sub 2}O)]·2(H{sub 2}O) (1) and [Pb(ndc)]{sub n} (2), where H{sub 2}idiac=iminodiacetic acid, phen=1,10-phenanthroline and H{sub 2}ndc=naphthalene-2,6-dicarboxylic acid, have been synthesized and structurally characterized. Single crystal X-ray diffraction analysis showed that compound 1 is a discrete trinuclear complex (of two-fold symmetry) which evolves to a supramolecular 3D network via π–π interactions, while in compound 2 the naphthalene dicarboxylate anion act as a linker to form a three dimensional architecture, where the anion adopts a bis-(bidentate bridging) coordination mode connecting four Pb(II) centers. The photoluminescence property of the two complexes has been studied. - graphical abstract: Two new topologically different 1D coordination polymers formed by Pb{sub 4} clusters have been synthesized and characterized by x-ray analysis. The luminescence and thermal properties have been studied. - Highlights: • 1 is a trinuclear complex of Pb(II) growing to 3D network via weak interactions. • In 1, layers of (4,4) rhomboidal topology are identified. • In 2, the ndc anion adopts interesting bis-(bidentate bridging) coordination. • In 2, network is reinforced by C–H…π-ring interactions between the ndc rings.

  19. Two new Zn(II) coordination polymers based on mixed pipemidic acid and flexible aromatic dicarboxylic acid ligands: Syntheses, crystal structures and luminescent properties

    NASA Astrophysics Data System (ADS)

    Jia, Yanxia; Zhou, Pingping

    2016-09-01

    Two new Zn(II) coordination polymers, namely [Zn(4,4‧-sdb) (HPPA)]n (1) and [Zn(2,2‧-bpdc)0.5(PPA)]n (2) (4,4‧-H2sdb = 4,4‧-sulfonyldibenzoate, 2,2‧-H2bpdc = 2,2‧-biphenyldicarboxylic acid, HPPA = pipemidic acid) were successfully obtained under hydrothermal conditions. These two compounds were further characterized by single-crystal X-ray diffraction analyses, elemental analyses, powder X-ray diffraction (PXRD) analyses and IR spectra. Compound 1 features a 1D chain structure, which further extended into a 3D supramolecular framework via intermolecular hydrogen bonds and weak van der Waals interactions, and compound 2 features a 3D framework with 6-connected α-Po-type topology. The structural regulation for these two compounds was successfully achieved by changing the flexible aromatic dicarboxylic acid ligand. Moreover, the thermal stabilities and luminescent properties for these two compounds were also investigated.

  20. Luminescence properties of composites made of a europium(III) complex and electroluminescent polymers with different energy gaps

    NASA Astrophysics Data System (ADS)

    Morgado, Jorge; Charas, Ana; Fernandes, José A.; Gonçalves, Isabel S.; Carlos, Luis D.; Alcácer, Luis

    2006-08-01

    We present the optoelectronic properties of composites made of a europium(III) complex, Eu(NTA)3 phen (where NTA=1-(2-naphthoyl)-3,3,3-trifluoroacetonate; phen=1,10-phenantroline), dispersed in three electroluminescent polymers, namely, poly(N-vinylcarbazole), poly(9,9-dioctylfluorene) and poly(9,9-dioctylfluorene-alt-benzothiadiazole). We find that the photo- and electroluminescence (EL) properties of these composites are well rationalized in terms of the relative position of the frontier levels of the host polymers and of the europium complex. We find also that charge recombination at the europium complex sites plays a key role on the EL properties of the composites.

  1. High-Performance, Semi-Interpenetrating Polymer Network

    NASA Technical Reports Server (NTRS)

    Pater, Ruth H.; Lowther, Sharon E.; Smith, Janice Y.; Cannon, Michelle S.; Whitehead, Fred M.; Ely, Robert M.

    1992-01-01

    High-performance polymer made by new synthesis in which one or more easy-to-process, but brittle, thermosetting polyimides combined with one or more tough, but difficult-to-process, linear thermoplastics to yield semi-interpenetrating polymer network (semi-IPN) having combination of easy processability and high tolerance to damage. Two commercially available resins combined to form tough, semi-IPN called "LaRC-RP49." Displays improvements in toughness and resistance to microcracking. LaRC-RP49 has potential as high-temperature matrix resin, adhesive, and molding resin. Useful in aerospace, automotive, and electronic industries.

  2. Semi-interpenetrating polymer network for tougher and more microcracking resistant high temperature polymers

    NASA Technical Reports Server (NTRS)

    Pater, Ruth H. (Inventor)

    1992-01-01

    This invention is a semi-interpenetrating polymer network which includes a high performance thermosetting polyimide having a nadic end group acting as a crosslinking site and a high performance linear thermoplastic polyimide. An improved high temperature matrix resin is provided which is capable of performing at 316 C in air for several hundreds of hours. This resin has significantly improved toughness and microcracking resistance, excellent processability and mechanical performance, and cost effectiveness.

  3. Photoinduced proton transfer coupled with energy transfer: Mechanism of sensitized luminescence of terbium ion by salicylic acid doped in polymer.

    PubMed

    Misra, Vinita; Mishra, Hirdyesh

    2008-06-28

    In the present work, excited state intramolecular proton transfer (ESIPT) in salicylic acid (SA) monoanion and subsequent sensitization of Tb(3+) ion in polyvinyl alcohol (PVA) have been studied. The study has been carried out both by steady state and time domain fluorescence measurement techniques at room temperature. It is found that the SA completely ionizes and exists as monoanion in PVA. It exhibits a large Stokes shifted blue emission (10 000 cm(-1)) due to ESIPT and shows a decay time of 6.85 ns. On the other hand, Tb(3+) ion shows a very weak green emission and a decay time of approximately 641 mus in PVA film. Upon incorporating Tb(3+) ion in SA doped PVA film, both intensity and decay time of SA decrease and sensitized emission from Tb(+3) ion along with 3.8 mus rise time is observed. Energy transfer is found to take place both from excited singlet as well as triplet states. A brief description of the properties of the present system from the viewpoint of luminescent solar collector material is addressed. PMID:18601359

  4. Monitoring Delamination of Thermal Barrier Coating During Interrupted High-Heat Flux Laser Testing Using Upconversion Luminescence Imaging

    NASA Technical Reports Server (NTRS)

    Eldridge, Jeffrey I.; Zhu, Dongming; Wolfe, Douglas E.

    2011-01-01

    Upconversion luminescence imaging of thermal barrier coatings (TBCs) has been shown to successfully monitor TBC delamination progression during interrupted furnace cycling. However, furnace cycling does not adequately model engine conditions where TBC-coated components are subjected to significant heat fluxes that produce through-thickness temperature gradients that may alter both the rate and path of delamination progression. Therefore, new measurements are presented based on luminescence imaging of TBC-coated specimens subjected to interrupted high-heat-flux laser cycling exposures that much better simulate the thermal gradients present in engine conditions. The TBCs tested were deposited by electron-beam physical vapor deposition (EB-PVD) and were composed of 7wt% yttria-stabilized zirconia (7YSZ) with an integrated delamination sensing layer composed of 7YSZ co-doped with erbium and ytterbium (7YSZ:Er,Yb). The high-heat-flux exposures that produce the desired through-thickness thermal gradients were performed using a high power CO2 laser operating at a wavelength of 10.6 microns. Upconversion luminescence images revealed the debond progression produced by the cyclic high-heat-flux exposures and these results were compared to that observed for furnace cycling.

  5. A series of Zn/Cd coordination polymers constructed from 1,4-naphthalenedicarboxylate and N-donor ligands: Syntheses, structures and luminescence sensing of Cr3+ in aqueous solutions

    NASA Astrophysics Data System (ADS)

    Hu, Dong-Cheng; Fan, Yan; Si, Chang-Dai; Wu, Ya-Jun; Dong, Xiu-Yan; Yang, Yun-Xia; Yao, Xiao-Qiang; Liu, Jia-Cheng

    2016-09-01

    A novel series of Zn/Cd coordination polymers based on H3L, namely, [Zn2(HL)2(bipy)2(H2O)6]n (1), [Zn(HL)(phen)]n (2), [Cd3L2(bbi)3]n (3), [Zn3L2(bbi)3]n (4) [(H3L =4-[(1-carboxynaphthalen-2-yl)oxy]phthalic acid, bipy =4,4‧-bipyridine, phen =1,10-phenanthroline, bbi =1,1‧-(1,4-butanediyl)bis(imidazole] have been successfully synthesized by solvothermal reaction. Compound 1 possesses two diverse 1D chains constructed by different bipy coligands, which were further connected to form a 3D supramolecular architecture by hydrogen bonding interactions. Compound 2 possesses a complicated 1D chain based on secondary building unit (SBU) with binuclear Zn cluster. Compounds 3 and 4 exhibit similar 2D→3D framework, which can be rationalized as (3,4,4)-connected 3D net with a Schläfli symbol of (63.8.102)2(63)2(64.8.10). In particular, compound 3 exhibited a high sensitivity for Cr3+ in aqueous solutions, which suggest that compound 3 is a promising luminescent probe for selectively sensing Cr3+.

  6. Influence of high magnetic field on the luminescence of Eu{sup 3+}-doped glass ceramics

    SciTech Connect

    Jiang, Wei; Chen, Weibo; Chen, Ping; Xu, Beibei; Zheng, Shuhong; Guo, Qiangbing; Liu, Xiaofeng E-mail: qjr@zju.edu.cn; Zhang, Junpei; Han, Junbo; Qiu, Jianrong E-mail: qjr@zju.edu.cn

    2014-09-28

    Rare earth (RE) doped materials have been widely exploited as the intriguing electronic configuration of RE ions offers diverse functionalities from optics to magnetism. However, the coupling of magnetism with photoluminescence (PL) in such materials has been rarely reported in spite of its fundamental significance. In the present paper, the effect of high pulsed magnetic field on the photoluminescence intensity of Eu{sup 3+}-doped nano-glass-ceramics has been investigated. In our experiment, Eu-doped oxyfluoride glass and glass ceramic were prepared by the conventional melt-quenching process and controlled heat treatment. The results demonstrate that the integrated PL intensity of Eu{sup 3+} decreases with the enhancement of magnetic field, which can be interpreted in terms of cooperation effect of Zeeman splitting and magnetic field induced change in site symmetry. Furthermore, as a result of Zeeman splitting, both blue and red shift in the emission peaks of Eu{sup 3+} can be observed, and this effect becomes more prominent with the increase of magnetic field. Possible mechanisms associated with the observed magneto-optical behaviors are suggested. The results of the present paper may open a new gate for modulation of luminescence by magnetic field and remote optical detection of magnetic field.

  7. Luminescence of LiNbO3:MgO,Cr crystals under high pressure

    NASA Astrophysics Data System (ADS)

    Kamińska, A.; Dmochowski, J. E.; Suchocki, A.; Garcia-Sole, J.; Jaque, F.; Arizmendi, L.

    1999-09-01

    The results of high-pressure studies of LiNbO3:Cr(0.2%), Mg crystals doped with two concentrations of magnesium (2% and 5.5%) are reported. The results reveal information about the electronic structure of different Cr3+ centers in lithium niobate crystals. There are three major Cr3+ centers (denoted by α, β, and γ) in the crystal with 2% of magnesium. These centers correspond to Cr3+ ions in Li+ sites with different crystal field. At ambient pressure the α center experiences strong crystal field and the β and γ centers are the intermediate crystal-field centers. The energy differences between the 4T2 and 2E levels are positive and negative for the β and the γ centers, respectively. Additional broadband luminescence observed in the sample with 5.5% of magnesium even at pressure of almost 100 kbar testifies that another very weak crystal-field center exists in this crystal. This center (denoted by δ) correponds to Cr3+ ions located in Nb5+ sites. The R lines of the Cr3+ centers exhibit very large redshift with pressure of about 3 cm-1/kbar.

  8. Iptycenes in the design of high performance polymers.

    PubMed

    Swager, Timothy M

    2008-09-01

    This Account details the use of building blocks known as iptycene units, which are particularly useful in the design of advanced materials because of their three-dimensional, noncompliant structures. Iptycenes are built upon [2,2,2]-ring systems in which the bridges are aromatic rings, and the simplest member of this class of compounds is triptycene. Iptycenes can provide steric blocking, which can prevent strong interactions between polymeric chromophores that have a strong tendency to form nonemissive exciplex complexes. Iptycene-containing conjugated polymers are exceptionally stable and display solution-like emissive spectra and quantum yields in the solid state. This application of iptycenes has enabled new vapor detection methods for ultratrace detection of high explosives that are now used by the U.S. military. The three-dimensional shape of iptycenes creates interstitial space (free volume) around the molecules. This space can confer size selectivity in sensory responses and also promotes alignment in oriented polymers and liquid crystals. Specifically, the iptycene-containing polymers and molecules align in the anisotropic host material in a way that minimizes the free volume. This effect can be used to align molecules contrary to what would be predicted by conventional models on the basis of aspect ratios. In one demonstration, we show that an iptycene polymer aligns orthogonally to the host polymer when stretched, and these structures approximate molecular versions of woven cloth. In liquid crystal solutions, the conjugated iptycene-containing polymers exhibit greater electronic delocalization, and the transport of excited states along the polymer backbone is observed. Structures that preserve high degrees of internal free volume can also be designed to create low dielectric constant insulators. These materials have high temperature stability (>500 degrees C) and hardness that make them potential interlayer dielectric materials for integrated circuits

  9. High-aspect ratio magnetic nanocomposite polymer cilium

    NASA Astrophysics Data System (ADS)

    Rahbar, M.; Tseng, H. Y.; Gray, B. L.

    2014-03-01

    This paper presents a new fabrication technique to achieve ultra high-aspect ratio artificial cilia micro-patterned from flexible highly magnetic rare earth nanoparticle-doped polymers. We have developed a simple, inexpensive and scalable fabrication method to create cilia structures that can be actuated by miniature electromagnets, that are suitable to be used for lab-on-a chip (LOC) and micro-total-analysis-system (μ-TAS) applications such as mixers and flow-control elements. The magnetic cilia are fabricated and magnetically polarized directly in microfluidic channels or reaction chambers, allowing for easy integration with complex microfluidic systems. These cilia structures can be combined on a single chip with other microfluidic components employing the same permanently magnetic nano-composite polymer (MNCP), such as valves or pumps. Rare earth permanent magnetic powder, (Nd0.7Ce0.3)10.5Fe83.9B5.6, is used to dope polydimethylsiloxane (PDMS), resulting in a highly flexible M-NCP of much higher magnetization and remanence [1] than ferromagnetic polymers typically employed in magnetic microfluidics. Sacrificial poly(ethylene-glycol) (PEG) is used to mold the highly magnetic polymer into ultra high-aspect ratio artificial cilia. Cilia structures with aspect ratio exceeding 8:0.13 can be easily fabricated using this technique and are actuated using miniature electromagnets to achieve a high range of motion/vibration.

  10. New AIE-active pyrimidine-based boronfluoride complexes with high solid-state emission and reversible mechanochromism luminescence behavior.

    PubMed

    Qi, Fen; Lin, Jianjian; Wang, Xiaoqing; Cui, Peng; Yan, Hui; Gong, Shuwen; Ma, Chunlin; Liu, Zhipeng; Huang, Wei

    2016-04-25

    A new family of pyrimidine-based BF2 complexes () with aggregation-induced emission (AIE) and mechanochromic luminescence properties were developed. These compounds exhibit intense fluorescence in their aggregation/solid-state resulting from their large Stokes shift and AIE. X-ray crystallographic analysis shows that the weak intermolecular interactions by fixing the molecular conformations of are responsible for the intense fluorescence in solid-state. In addition to their pronounced AIE behaviour, also exhibits a reversible chromic response to grinding, and a distinct red-shift of emission is observed. The high solid-state luminescence and grinding-stimuli response properties of these compounds make them potential candidates for smart materials. PMID:26938704

  11. Significantly elevated dielectric permittivity of Si-based semiconductor/polymer 2-2 composites induced by high polarity polymers

    NASA Astrophysics Data System (ADS)

    Feng, Yefeng; Gong, Honghong; Xie, Yunchuan; Wei, Xiaoyong; Zhang, Zhicheng

    2016-02-01

    To disclose the essential influence of polymer polarity on dielectric properties of polymer composites filled with semiconductive fillers, a series of Si-based semiconductor/polymer 2-2 composites in a series model was fabricated. The dielectric permittivity of composites is highly dependant on the polarity of polymer layers as well as the electron mobility in Si-based semiconductive sheets. The huge dielectric permittivity achieved in Si-based semiconductive sheets after being coated with high polarity polymer layers is inferred to originate from the strong induction of high polarity polymers. The increased mobility of the electrons in Si-based semiconductive sheets coated by high polarity polymer layers should be responsible for the significantly enhanced dielectric properties of composites. This could be facilely achieved by either increasing the polarity of polymer layers or reducing the percolative electric field of Si-based semiconductive sheets. The most promising 2-2 dielectric composite was found to be made of α-SiC with strong electron mobility and poly(vinyl alcohol) (PVA) with high polarity, and its highest permittivity was obtained as 372 at 100 Hz although the permittivity of α-SiC and PVA is 3-5 and 15, respectively. This work may help in the fabrication of high dielectric constant (high-k) composites by tailoring the induction effect of high polarity polymers to semiconductors.

  12. High-Performance Polymers Having Low Melt Viscosities

    NASA Technical Reports Server (NTRS)

    Jensen, Brian J.

    2005-01-01

    High-performance polymers that have improved processing characteristics, and a method of making them, have been invented. One of the improved characteristics is low (relative to corresponding prior polymers) melt viscosities at given temperatures. This characteristic makes it possible to utilize such processes as resin-transfer molding and resin-film infusion and to perform autoclave processing at lower temperatures and/or pressures. Another improved characteristic is larger processing windows that is, longer times at low viscosities. Other improved characteristics include increased solubility of uncured polymer precursors that contain reactive groups, greater densities of cross-links in cured polymers, improved mechanical properties of the cured polymers, and greater resistance of the cured polymers to chemical attack. The invention is particularly applicable to poly(arylene ether)s [PAEs] and polyimides [PIs] that are useful as adhesives, matrices of composite materials, moldings, films, and coatings. PAEs and PIs synthesized according to the invention comprise mixtures of branched, linear, and star-shaped molecules. The monomers of these polymers can be capped with either reactive end groups to obtain thermosets or nonreactive end groups to obtain thermoplastics. The synthesis of a polymeric mixture according to the invention involves the use of a small amount of a trifunctional monomer. In the case of a PAE, the trifunctional monomer is a trihydroxy- containing compound for example, 1,3,5-trihydroxybenzene (THB). In the case of a PI, the trifunctional monomer is a triamine for example, triamino pyrimidine or melamine. In addition to the aforementioned trifunctional monomer, one uses the difunctional monomers of the conventional formulation of the polymer in question (see figure). In cases of nonreactive end caps, the polymeric mixtures of the invention have melt viscosities and melting temperatures lower than those of the corresponding linear polymers of equal

  13. MgO:Li,Ce,Sm as a high-sensitivity material for Optically Stimulated Luminescence dosimetry

    PubMed Central

    Oliveira, Luiz C.; Yukihara, Eduardo G.; Baffa, Oswaldo

    2016-01-01

    The goal of this work was to investigate the relevant dosimetric and luminescent properties of MgO:Li3%,Ce0.03%,Sm0.03%, a newly-developed, high sensitivity Optically Stimulated Luminescence (OSL) material of low effective atomic number (Zeff = 10.8) and potential interest for medical and personal dosimetry. We characterized the thermoluminescence (TL), OSL, radioluminescence (RL), and OSL emission spectrum of this new material and carried out a preliminary investigation on the OSL signal stability. MgO:Li,Ce,Sm has a main TL peak at ~180 °C (at a heating rate of 5 °C/s) associated with Ce3+ and Sm3+ emission. The results indicate that the infrared (870 nm) stimulated OSL from MgO:Li,Ce,Sm has suitable properties for dosimetry, including high sensitivity to ionizing radiation (20 times that of Al2O3:C, under the measurement conditions) and wide dynamic range (7 μGy–30 Gy). The OSL associated with Ce3+ emission is correlated with a dominant, practically isolated peak at 180 °C. Fading of ~15% was observed in the first hour, probably due to shallow traps, followed by subsequent fading of 6–7% over the next 35 days. These properties, together with the characteristically fast luminescence from Ce3+, make this material also a strong candidate for 2D OSL dose mapping. PMID:27076349

  14. MgO:Li,Ce,Sm as a high-sensitivity material for Optically Stimulated Luminescence dosimetry

    NASA Astrophysics Data System (ADS)

    Oliveira, Luiz C.; Yukihara, Eduardo G.; Baffa, Oswaldo

    2016-04-01

    The goal of this work was to investigate the relevant dosimetric and luminescent properties of MgO:Li3%,Ce0.03%,Sm0.03%, a newly-developed, high sensitivity Optically Stimulated Luminescence (OSL) material of low effective atomic number (Zeff = 10.8) and potential interest for medical and personal dosimetry. We characterized the thermoluminescence (TL), OSL, radioluminescence (RL), and OSL emission spectrum of this new material and carried out a preliminary investigation on the OSL signal stability. MgO:Li,Ce,Sm has a main TL peak at ~180 °C (at a heating rate of 5 °C/s) associated with Ce3+ and Sm3+ emission. The results indicate that the infrared (870 nm) stimulated OSL from MgO:Li,Ce,Sm has suitable properties for dosimetry, including high sensitivity to ionizing radiation (20 times that of Al2O3:C, under the measurement conditions) and wide dynamic range (7 μGy–30 Gy). The OSL associated with Ce3+ emission is correlated with a dominant, practically isolated peak at 180 °C. Fading of ~15% was observed in the first hour, probably due to shallow traps, followed by subsequent fading of 6–7% over the next 35 days. These properties, together with the characteristically fast luminescence from Ce3+, make this material also a strong candidate for 2D OSL dose mapping.

  15. MgO:Li,Ce,Sm as a high-sensitivity material for Optically Stimulated Luminescence dosimetry.

    PubMed

    Oliveira, Luiz C; Yukihara, Eduardo G; Baffa, Oswaldo

    2016-01-01

    The goal of this work was to investigate the relevant dosimetric and luminescent properties of MgO:Li3%,Ce0.03%,Sm0.03%, a newly-developed, high sensitivity Optically Stimulated Luminescence (OSL) material of low effective atomic number (Zeff = 10.8) and potential interest for medical and personal dosimetry. We characterized the thermoluminescence (TL), OSL, radioluminescence (RL), and OSL emission spectrum of this new material and carried out a preliminary investigation on the OSL signal stability. MgO:Li,Ce,Sm has a main TL peak at ~180 °C (at a heating rate of 5 °C/s) associated with Ce(3+) and Sm(3+) emission. The results indicate that the infrared (870 nm) stimulated OSL from MgO:Li,Ce,Sm has suitable properties for dosimetry, including high sensitivity to ionizing radiation (20 times that of Al2O3:C, under the measurement conditions) and wide dynamic range (7 μGy-30 Gy). The OSL associated with Ce(3+) emission is correlated with a dominant, practically isolated peak at 180 °C. Fading of ~15% was observed in the first hour, probably due to shallow traps, followed by subsequent fading of 6-7% over the next 35 days. These properties, together with the characteristically fast luminescence from Ce(3+), make this material also a strong candidate for 2D OSL dose mapping. PMID:27076349

  16. Development of highly luminescent and water-dispersible lanthanide-based nanomaterials for potential bio-medical imaging

    NASA Astrophysics Data System (ADS)

    Attanayake, Gayanthi Kumari

    Lanthanide metal ions exhibit fascinating optical and magnetic properties. Lanthanide-based nanomaterials have potential applications in optical devices, telecommunication, electroluminescent devices, bio-analytical sensors, and bio-medical imaging technology. Despite the recent developments, low luminescence characteristics, poor water solubility, and poor cell selectivity of lanthanide-based materials limit their use in bio-medical applications. This project is designed to mainly improve the luminescence properties of Eu(III)-based nanomaterials for their potential use in biomedical applications. In addition, we explore synthetic methods to enhance the water dispersibility and melanoma cell selectivity of the nanoparticles. Current research is designed to address the above mentioned drawbacks of lanthanide-based nanomaterials. Two different nanoparticle systems were developed in this project. i. europium (Eu)-based down-converting nanoparticles, ii. ytterbium (Yb)- erbium (Er)-based upconverting nanoparticles. Many down-converting nanoparticle systems suffer from low-luminescence efficiencies due to their poor light absorption by direct excitation of the lanthanide ions. In order to improve the luminescence characteristics, we have designed a novel nanomaterial by surface-coating it with organic chromophores having strong light absorption properties. LaEuF3.AEP (La=lanthanum, AEP = aminoethyl phosphate) nanoparticles were successfully synthesized using a low temperature heating method and Eu-based NaYF4 nanoparticles were synthesized using a high temperature heating method. A ligand exchange procedure was developed to functionalize the surface of the nanoparticles with an organic chromophore, TTA (thenoyltrifluoroacetone). The TTA functionalized Eu(III)-based nanoparticles exhibit impressive luminescence enhancements utilizing the sensitization effect. Poor water solubility is the main drawback of the upconverting nanoparticles for bio-medical applications. We

  17. Luminescence and luminescence quenching of highly efficient Y2Mo4O15:Eu(3+) phosphors and ceramics.

    PubMed

    Janulevicius, Matas; Marmokas, Paulius; Misevicius, Martynas; Grigorjevaite, Julija; Mikoliunaite, Lina; Sakirzanovas, Simas; Katelnikovas, Arturas

    2016-01-01

    A good LED phosphor must possess strong enough absorption, high quantum yields, colour purity, and quenching temperatures. Our synthesized Y2Mo4O15:Eu(3+) phosphors possess all of these properties. Excitation of these materials with near-UV or blue radiation yields bright red emission and the colour coordinates are relatively stable upon temperature increase. Furthermore, samples doped with 50% Eu(3+) showed quantum yields up to 85%, what is suitable for commercial application. Temperature dependent emission spectra revealed that heavily Eu(3+) doped phosphors possess stable emission up to 400 K and lose half of the efficiency only at 515 K. In addition, ceramic disks of Y2Mo4O15:75%Eu(3+) phosphor with thickness of 0.71 and 0.98 mm were prepared and it turned out that they efficiently convert radiation of 375 and 400 nm LEDs to the red light, whereas combination with 455 nm LED yields purple colour. PMID:27180941

  18. Luminescence and luminescence quenching of highly efficient Y2Mo4O15:Eu3+ phosphors and ceramics

    PubMed Central

    Janulevicius, Matas; Marmokas, Paulius; Misevicius, Martynas; Grigorjevaite, Julija; Mikoliunaite, Lina; Sakirzanovas, Simas; Katelnikovas, Arturas

    2016-01-01

    A good LED phosphor must possess strong enough absorption, high quantum yields, colour purity, and quenching temperatures. Our synthesized Y2Mo4O15:Eu3+ phosphors possess all of these properties. Excitation of these materials with near-UV or blue radiation yields bright red emission and the colour coordinates are relatively stable upon temperature increase. Furthermore, samples doped with 50% Eu3+ showed quantum yields up to 85%, what is suitable for commercial application. Temperature dependent emission spectra revealed that heavily Eu3+ doped phosphors possess stable emission up to 400 K and lose half of the efficiency only at 515 K. In addition, ceramic disks of Y2Mo4O15:75%Eu3+ phosphor with thickness of 0.71 and 0.98 mm were prepared and it turned out that they efficiently convert radiation of 375 and 400 nm LEDs to the red light, whereas combination with 455 nm LED yields purple colour. PMID:27180941

  19. Luminescence and luminescence quenching of highly efficient Y2Mo4O15:Eu3+ phosphors and ceramics

    NASA Astrophysics Data System (ADS)

    Janulevicius, Matas; Marmokas, Paulius; Misevicius, Martynas; Grigorjevaite, Julija; Mikoliunaite, Lina; Sakirzanovas, Simas; Katelnikovas, Arturas

    2016-05-01

    A good LED phosphor must possess strong enough absorption, high quantum yields, colour purity, and quenching temperatures. Our synthesized Y2Mo4O15:Eu3+ phosphors possess all of these properties. Excitation of these materials with near-UV or blue radiation yields bright red emission and the colour coordinates are relatively stable upon temperature increase. Furthermore, samples doped with 50% Eu3+ showed quantum yields up to 85%, what is suitable for commercial application. Temperature dependent emission spectra revealed that heavily Eu3+ doped phosphors possess stable emission up to 400 K and lose half of the efficiency only at 515 K. In addition, ceramic disks of Y2Mo4O15:75%Eu3+ phosphor with thickness of 0.71 and 0.98 mm were prepared and it turned out that they efficiently convert radiation of 375 and 400 nm LEDs to the red light, whereas combination with 455 nm LED yields purple colour.

  20. High Density Polymer-Based Integrated Electgrode Array

    DOEpatents

    Maghribi, Mariam N.; Krulevitch, Peter A.; Davidson, James Courtney; Hamilton, Julie K.

    2006-04-25

    A high density polymer-based integrated electrode apparatus that comprises a central electrode body and a multiplicity of arms extending from the electrode body. The central electrode body and the multiplicity of arms are comprised of a silicone material with metal features in said silicone material that comprise electronic circuits.

  1. High efficiency all-polymer tandem solar cells

    NASA Astrophysics Data System (ADS)

    Yuan, Jianyu; Gu, Jinan; Shi, Guozheng; Sun, Jianxia; Wang, Hai-Qiao; Ma, Wanli

    2016-05-01

    In this work, we have reported for the first time an efficient all-polymer tandem cell using identical sub-cells based on P2F-DO:N2200. A high power conversion efficiency (PCE) of 6.70% was achieved, which is among the highest efficiencies for all polymer solar cells and 43% larger than the PCE of single junction cell. The largely improved device performance can be mainly attributed to the enhanced absorption of tandem cell. Meanwhile, the carrier collection in device remains efficient by optimizing the recombination layer and sub-cell film thickness. Thus tandem structure can become an easy approach to effectively boost the performance of current all polymer solar cells.

  2. High efficiency all-polymer tandem solar cells

    PubMed Central

    Yuan, Jianyu; Gu, Jinan; Shi, Guozheng; Sun, Jianxia; Wang, Hai-Qiao; Ma, Wanli

    2016-01-01

    In this work, we have reported for the first time an efficient all-polymer tandem cell using identical sub-cells based on P2F-DO:N2200. A high power conversion efficiency (PCE) of 6.70% was achieved, which is among the highest efficiencies for all polymer solar cells and 43% larger than the PCE of single junction cell. The largely improved device performance can be mainly attributed to the enhanced absorption of tandem cell. Meanwhile, the carrier collection in device remains efficient by optimizing the recombination layer and sub-cell film thickness. Thus tandem structure can become an easy approach to effectively boost the performance of current all polymer solar cells. PMID:27226354

  3. High efficiency all-polymer tandem solar cells.

    PubMed

    Yuan, Jianyu; Gu, Jinan; Shi, Guozheng; Sun, Jianxia; Wang, Hai-Qiao; Ma, Wanli

    2016-01-01

    In this work, we have reported for the first time an efficient all-polymer tandem cell using identical sub-cells based on P2F-DO:N2200. A high power conversion efficiency (PCE) of 6.70% was achieved, which is among the highest efficiencies for all polymer solar cells and 43% larger than the PCE of single junction cell. The largely improved device performance can be mainly attributed to the enhanced absorption of tandem cell. Meanwhile, the carrier collection in device remains efficient by optimizing the recombination layer and sub-cell film thickness. Thus tandem structure can become an easy approach to effectively boost the performance of current all polymer solar cells. PMID:27226354

  4. Syntheses, structures and luminescence for zinc coordination polymers based on a multifunctional 4‧-(3-carboxyphenyl)- 3,2‧:6‧,3″-terpyridine ligand

    NASA Astrophysics Data System (ADS)

    Cheng, Yue; Yang, Meng-Lin; Hu, Huai-Ming; Xu, Bing; Wang, Xiaofang; Xue, Ganglin

    2016-07-01

    Six new coordination polymers, [ZnLCl]n(1), [ZnL2]n·2nH2O (2), [Zn2L(o-bdc)(OH)]n·0.5nH2O (3), [Zn2L(m-bdc)(OH)]n·nH2O (4), [Zn2L2(p-bdc) (H2O)2]n·nH2O (5), [Zn2L(1,2,4-btc)(H2O)]n(6), (HL=4‧-(3-carboxyphenyl)- 3,2‧:6‧,3″-terpyridine, H2(o-bdc)= benzene-1,2-dicarboxylic acid, H2(m-bdc)= benzene-1,3-dicarboxylic acid, H2(p-bdc)= benzene-1,4-dicarboxylic acid, H3(1,2,4-btc)= benzene-1,2,4-tricarboxylic acid) have been synthesized under the hydrothermal conditions. Compound 1 displays a 3-connected 2D network structure with point symbol of {82.10}. Compound 2 exhibits 1D infinite loop chain structure. Compound 3 possesses a (3,8)-connected 3D framework composed of tetranuclear units with point symbol of {43}2{46.618.84}. Compound 4 features a typical 2D hcb network based on tetranuclear zinc(II) units with point symbol of {44.62}. Compound 5 presents a classical two-fold penetration sql network with point symbol of {63}. Compound 6 can be seen as a (3,3,6)-connected 3D net with point symbol of {42.64.89}{42.6}{63}. The thermal stability and luminescent properties of compounds 1-6 in the solid state are discussed in detail.

  5. Analytical modeling of relative luminescence efficiency of Al2O3:C optically stimulated luminescence detectors exposed to high-energy heavy charged particles.

    PubMed

    Sawakuchi, Gabriel O; Yukihara, Eduardo G

    2012-01-21

    The objective of this work is to test analytical models to calculate the luminescence efficiency of Al(2)O(3):C optically stimulated luminescence detectors (OSLDs) exposed to heavy charged particles with energies relevant to space dosimetry and particle therapy. We used the track structure model to obtain an analytical expression for the relative luminescence efficiency based on the average radial dose distribution produced by the heavy charged particle. We compared the relative luminescence efficiency calculated using seven different radial dose distribution models, including a modified model introduced in this work, with experimental data. The results obtained using the modified radial dose distribution function agreed within 20% with experimental data from Al(2)O(3):C OSLDs relative luminescence efficiency for particles with atomic number ranging from 1 to 54 and linear energy transfer in water from 0.2 up to 1368 keV µm(-1). In spite of the significant improvement over other radial dose distribution models, understanding of the underlying physical processes associated with these radial dose distribution models remain elusive and may represent a limitation of the track structure model. PMID:22173080

  6. Piezoresistance in polymer nanocomposites with high aspect ratio particles.

    PubMed

    Cattin, Cyrill; Hubert, Pascal

    2014-02-12

    In this paper, we address the problem of positive piezoresistance in high aspect ratio particle based polymer nanocomposites, a hybrid system at the center of research on flexible piezoresistive materials. We introduce a percolation theory based model relating the variation in electrical resistance to compressive strain and show that it gives accurate theoretical fits to experimental data presented in this paper, as well as to much of the available data in the literature. In contrast to existing theories, the model captures the characteristics of the particle network through experimentally definable parameters and does not rely on assumptions regarding the nature of the particles and/or the configuration of the network. It is further demonstrated that the presented theoretical framework is not limited to polymer nanocomposites with high aspect ratio particle but that it can explain piezoresistance in bulk electroconductive polymer nanocomposites in general. We find that the piezoresistive effect in such materials is rooted in a mechanical deformation induced change in the distribution of local conductances within the particle network, and we show that this change in the distribution of local conductances is well described by a strain dependent conductivity exponent, which scales with the magnitude of mechanical deformation. Besides, we demonstrate that these findings can be applied to the experimentally observed concentration dependence of the piezoresistance in polymer nanocomposites and, thus, to predicting the electric response to mechanical deformation at any particle concentration, which is expected to be highly instrumental in applied materials selection and performance evaluation. PMID:24410147

  7. Luminescent spectroscopy and structural properties of Ce3+-doped low-temperature X1-Y2SiO5 material prepared by polymer-assisted sol-gel method

    NASA Astrophysics Data System (ADS)

    Hamroun, M. S. E.; Guerbous, L.; Bensafi, A.

    2016-04-01

    Cerium (Ce3+)-doped monoclinic X1-Y2SiO5 (YSO)-type oxyorthosilicates powders were prepared by monomer and polymer-assisted sol-gel method. The present work aims to study the influence of ethylene glycol (EG) monomer, polyethylene glycol (PEG) polymer and polyvinyl alcohol (PVA) polymer, as fuels and nucleating agents for the crystallization, on structural and luminescence properties of the Ce3+ (xCe = 0.01)-doped Y2SiO5. The X-ray diffraction technique, field emission scanning electron microscopy, Fourier transform infrared spectroscopy and steady photoluminescence have been used to characterize the samples. It is found that the types of fuels affect the phase purity and luminescent characteristics of phosphors. All samples exhibit intense violet-blue asymmetric emission band in the range of 370-540 nm with a maximum intensity centered at around 420 nm assigned to the 5d → 4f (2F5/2, 2F7/2) interconfigurational transitions of Ce3+ ion in YSO nanomaterial. Finally, the vibronic coupling parameters are estimated and discussed.

  8. Synthesis, structures, luminescent and magnetic properties of four coordination polymers with the flexible 1,3-phenylenediacetate ligands

    SciTech Connect

    Gu, Jin-Zhong; Lv, Dong-Yu; Gao, Zhu-Qing; Liu, Jian-Zhao; Dou, Wei; Tang, Yu

    2011-03-15

    Four coordination polymers, [Zn(pda)(bpy)(H{sub 2}O)]{sub n}.nH{sub 2}O (1), [Cd(pda)(prz)(H{sub 2}O)]{sub n} (2), [Co{sub 3}({mu}{sub 3}-OH){sub 2}(pda){sub 2}(pyz)]{sub n}.2nH{sub 2}O (3) and [Pr{sub 2}(pda){sub 3}(H{sub 2}O){sub 2}]{sub n} (4) (H{sub 2}pda=1,3-phenylendiacetic acid, bpy=4,4'-bipyridine, prz=piperazine and pyz=pyrazine) have been hydrothermally synthesized and characterized. Complex 1 is a 1D wheel-like chain structure, which is further extended into a 3D metal-organic supramolecular framework by H-bonds and {pi}-{pi} stacking interactions. Complex 2 is a 1D ladder-like chain structure, which is also further extended into a 3D metal-organic supramolecular framework by H-bonds. Complex 3 possess a 2D sheet structure with infrequent two pairs of double-helix chains. Complex 4 features a 3D structure. Both 1 and 2 display strong blue fluorescent emission at room temperature. Magnetic susceptibility measurements of complexes 3 and 4 exhibit antiferromagnetic interactions between the nearest metal ions, with C=9.99 and 3.43 cm{sup 3} mol{sup -1} K, and {theta}=-23.9 and -46.3 K, respectively. -- Graphical abstract: Four new coordination polymers with 1,3-phenylenediacetate ligands have been hydrothermally synthesized and characterized. Complexes 1 and 2 display strong blue fluorescent emission at room temperature. Magnetic susceptibility measurements of 3 and 4 exhibit antiferromagnetic interactions between the nearest metal centers. Display Omitted Research highlights: > Coordinative property of H{sub 2}pda ligand was shown when bonded by different block metals. > Careful selection of co-ligand and metals resulted in dramatic framework evolution. > (c) The compounds constructed with Zn{sup 2+} and Cd{sup 2+} exhibit strong blue fluorescent emission. > The magneto-structural correlation of the complexes constructed with Co{sup 2+} and Pr{sup 3+} was elucidated.

  9. Synthesis, structures, luminescent and magnetic properties of four coordination polymers with the flexible 1,3-phenylenediacetate ligands

    NASA Astrophysics Data System (ADS)

    Gu, Jin-Zhong; Lv, Dong-Yu; Gao, Zhu-Qing; Liu, Jian-Zhao; Dou, Wei; Tang, Yu

    2011-03-01

    Four coordination polymers, [Zn(pda)(bpy)(H 2O)] n· nH 2O ( 1), [Cd(pda)(prz)(H 2O)] n ( 2), [Co 3( μ3-OH) 2(pda) 2(pyz)] n·2 nH 2O ( 3) and [Pr 2(pda) 3(H 2O) 2] n ( 4) (H 2pda=1,3-phenylendiacetic acid, bpy=4,4'-bipyridine, prz=piperazine and pyz=pyrazine) have been hydrothermally synthesized and characterized. Complex 1 is a 1D wheel-like chain structure, which is further extended into a 3D metal-organic supramolecular framework by H-bonds and π- π stacking interactions. Complex 2 is a 1D ladder-like chain structure, which is also further extended into a 3D metal-organic supramolecular framework by H-bonds. Complex 3 possess a 2D sheet structure with infrequent two pairs of double-helix chains. Complex 4 features a 3D structure. Both 1 and 2 display strong blue fluorescent emission at room temperature. Magnetic susceptibility measurements of complexes 3 and 4 exhibit antiferromagnetic interactions between the nearest metal ions, with C=9.99 and 3.43 cm 3 mol -1 K, and θ=-23.9 and -46.3 K, respectively.

  10. High performance carbon nanotube - polymer nanofiber hybrid fabrics

    NASA Astrophysics Data System (ADS)

    Yildiz, Ozkan; Stano, Kelly; Faraji, Shaghayegh; Stone, Corinne; Willis, Colin; Zhang, Xiangwu; Jur, Jesse S.; Bradford, Philip D.

    2015-10-01

    Stable nanoscale hybrid fabrics containing both polymer nanofibers and separate and distinct carbon nanotubes (CNTs) are highly desirable but very challenging to produce. Here, we report the first instance of such a hybrid fabric, which can be easily tailored to contain 0-100% millimeter long CNTs. The novel CNT - polymer hybrid nonwoven fabrics were created by simultaneously electrospinning nanofibers onto aligned CNT sheets which were drawn and collected on a grounded, rotating mandrel. Due to the unique properties of the CNTs, the hybrids show very high tensile strength, very small pore size, high specific surface area and electrical conductivity. In order to further examine the hybrid fabric properties, they were consolidated under pressure, and also calendered at 70 °C. After calendering, the fabric's strength increased by an order of magnitude due to increased interactions and intermingling with the CNTs. The hybrids are highly efficient as aerosol filters; consolidated hybrid fabrics with a thickness of 20 microns and areal density of only 8 g m-2 exhibited ultra low particulate (ULPA) filter performance. The flexibility of this nanofabrication method allows for the use of many different polymer systems which provides the opportunity for engineering a wide range of nanoscale hybrid materials with desired functionalities.Stable nanoscale hybrid fabrics containing both polymer nanofibers and separate and distinct carbon nanotubes (CNTs) are highly desirable but very challenging to produce. Here, we report the first instance of such a hybrid fabric, which can be easily tailored to contain 0-100% millimeter long CNTs. The novel CNT - polymer hybrid nonwoven fabrics were created by simultaneously electrospinning nanofibers onto aligned CNT sheets which were drawn and collected on a grounded, rotating mandrel. Due to the unique properties of the CNTs, the hybrids show very high tensile strength, very small pore size, high specific surface area and electrical

  11. High chi polymer development for DSA applications using RAFT technology

    NASA Astrophysics Data System (ADS)

    Sheehan, Michael T.; Farnham, William B.; Tran, Hoang V.; Londono, J. David; Brun, Yefim

    2013-03-01

    Directed self-assembly (DSA) of block copolymers is proving to be an interesting and innovative method to make three-dimensional periodic, uniform patterns useful in a variety of microelectronics applications. Attributes critical to acceptable DSA performance of block copolymers include molecular weight uniformity, final purity, and reproducibility in all the steps involved in producing the polymers. Reversible Addition Fragmentation Chain Transfer (RAFT) polymerization technology enables the production of such materials provided that careful process monitoring and compositional homogeneity measurement systems are employed. It is uniquely suited to construction of multiblocks with components of widely divergent surface energies and functionality. We describe a high chi diblock system comprising partially fluorinated methacrylates and substituted styrenics. While special new polymer separation strategies involving controlled polymer particle assembly in liquid media are required for some monomer systems and molecular weight regimes, we have been able to demonstrate high yield and compositionally homogeneous diblocks of lamellar and cylindrical morphology with polydispersities < 1.1. During purification processes, these diblock materials undergo assembly processes in liquid media, and with appropriate controls, this allows for removal of soluble homopolymer contaminants. SAXS analyses of solid polymer samples provide estimates of lamellar d-spacing, and a good correlation with molecular weight is shown. This system will be described.

  12. Simulated space environmental effects on some experimental high performance polymers

    NASA Technical Reports Server (NTRS)

    Connell, John W.

    1991-01-01

    Organic polymeric materials are currently being considered for long term use (more than 10 years) in structural (adhesives and composite matrices) and functional (films and coatings) applications on spacecraft. Although organic polymers have been utilized successfully in short term missions, the long term durability of these materials in space is of concern. As part of a NASA effort on high performance polymers for potential space applications, various experimental polymeric materials recently synthesized at NASA Langley Research Center were evaluated under simulated space environmental conditions. Experimental resins from blends of acetylene terminated materials, poly(arylene ether)s and low color polyimides were exposed to high energy electron and ultraviolet radiation in an attempt to simulate space environmental effects. Thin films, neat resin moldings and carbon fiber reinforced composites were exposed and the effect on certain polymer properties were determined. This paper reviews recent research involving the effects of various radiation exposures on the physical, optical and mechanical properties of several experimental polymer systems.

  13. Elastic repulsion from polymer brush layers exhibiting high protein repellency.

    PubMed

    Inoue, Yuuki; Nakanishi, Tomoaki; Ishihara, Kazuhiko

    2013-08-27

    Hydrophilic poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) and poly(2-hydroxyethyl methacrylate) (PHEMA) brush layers with different thicknesses and graft densities were prepared to construct a model surface to elucidate protein-surface interactions. In particular, we focused on the steric repulsion of hydrophilic polymer layers as one of the surface properties that strongly influence protein adsorption and employed force-versus-distance (f-d) curve measurements obtained via atomic force microscopy to quantitatively evaluate the steric repulsion force, which is also referred to as the "elastic repulsion energy." We also analyzed direct interactions between the surface and proteins via the f-d curve, because these interactions trigger the protein-adsorption phenomenon. Protein-surface interactions were extremely suppressed at surfaces with high elastic repulsion energies and highly dense polymer brush structures, which is in contrast to those at surfaces with low elastic repulsion energies and low density of the grafted polymer layers. These results indicate that the elastic repulsion from the grafted polymer layer at the surface is an important parameter for controlling protein-surface interactions and protein adsorption phenomenon. PMID:23898820

  14. Utilizing Nanofabrication to Construct Strong, Luminescent Materials

    SciTech Connect

    Chen, Wei; Huang, Gang; Lu, Hong B.; McCready, David E.; Joly, Alan G.; Bovin, Jan-Olov

    2006-05-28

    Luminescent materials have been utilized widely in applications from lighting to sensing. The new development of technologies based on luminescence properties requires the materials to have high luminescence efficiency and mechanical strength. In this article, we report the fabrication of luminescent materials possessing high mechanical strength by nanofabrication with polyvinyl alcohol used as a stabilizer or coupling agent. X-ray diffraction and high resolution transmission microscope observations reveal that the nanocomposite sample contains ZnS and ZnO nanoparticles as well as kozoite and sodium nitrate. The mechanical strength and hardness of these nanocomposite materials are higher than polycarbonate and some carbon nanotube reinforced nanocomposites. Strong luminescence is observed in the new nanocomposites and the luminescence intensity does not degrade following up to 30 minutes of X-ray irradiation. Our results indicate that nanofabrication may provide a good method to improve the mechanical strength of luminescent materials for some applications in which high strength luminescent materials are needed.

  15. High performance polymers and polymer matrix composites for spacecraft structural applications

    NASA Technical Reports Server (NTRS)

    Bowles, D. E.; Connell, J. W.

    1992-01-01

    A program implemented by NASA Langley Research Center to develop and evaluate new polymers and polymer matrix composites for spacecraft structural applications is examined. Various polymeric films, moldings, and adhesives are evaluated for resistance to atomic oxygen and high energy electron and UV radiation. Thin films from the poly(arylene ether)s containing phenylphosphine oxide groups and the siloxane-epoxies exhibited minor weight loss compared to Kapton polyimide after exposure. Large doses (greater than 10 exp 9 rads) of electron radiation, simulating 30 yr of exposure in GEO, are found to alter the chemical structure of epoxies by both chain scission and cross-linking. The thermal cycling representative of both LEO and GEO environments can cause microcracking in composites which can in turn affect the dimensional stability and produce mechanical property reductions. The processing and fabrication issues associated with precision composite spacecraft components are also addressed.

  16. Highly Ordered Single Conjugated Polymer Chain Rod Morphologies

    SciTech Connect

    Adachi, Takuji; Brazard, Johanna; Chokshi, Paresh; Ganesan, Venkat; Bolinger, Joshua; Barbara, Paul F.

    2010-10-15

    We have reexamined the fluorescence polarization anisotropy of single polymer chains of the prototypical conjugated polymer poly[2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) isolated in a poly(methyl methacrylate) (PMMA) matrix employing improved synthetic samples that contain a much smaller number of tetrahedral chemical defects per chain. The new measurements reveal a much larger fraction of highly anisotropic MEH-PPV chains, with >70% of the chains exhibiting polarization anisotropy values falling in the range of 0.6-0.9. High anisotropy is strong evidence for a rod-shaped conformation. A comparison of the experimental results with coarse grain, beads on a chain simulations reveals that simulations with the usual bead-bead pairwise additive potentials cannot reproduce the observed large fraction of high polarization values. Apparently, this type of potential lacks some yet to be identified molecular feature that is necessary to accurately simulate the experimental results.

  17. Laser welding of polymers using high-power diode lasers

    NASA Astrophysics Data System (ADS)

    Bachmann, Friedrich G.; Russek, Ulrich A.

    2002-06-01

    Laser welding of polymers using high power diode lasers offers specific process advantages over conventional technologies, such as short process times while providing optically and qualitatively valuable weld seams, contactless yielding of the joining energy, absence of process induced vibrations, imposing minimal thermal stress and avoiding particle generation. Furthermore, this method exhibits high integration capabilities and automatization potential. Moreover, because of the current favorable cost development within the high power diode laser market laser welding of polymers has become more and more an industrially accepted joining method. This novel technology permits both, reliable high quality joining of mechanically and electronically highly sensitive micro components and hermetic sealing of macro components. There are different welding strategies available, which are adaptable to the current application. Within the frame of this discourse scientific and also application oriented result concerning laser transmission welding of polymers using preferably diode lasers are presented. Besides the sue laser system the fundamental process strategies as well as decisive process parameters are illustrated. The importance of optical, thermal and mechanical properties is discussed. Applications at real technical components will be presented, demonstrating the industrial implementation capability and the advantages of a novel technology.

  18. Laser welding of polymers using high-power diode lasers

    NASA Astrophysics Data System (ADS)

    Bachmann, Friedrich G.; Russek, Ulrich A.

    2003-09-01

    Laser welding of polymers using high power diode lasers offers specific process advantages over conventional technologies, such as short process times while providing optically and qualitatively valuable weld seams, contactless yielding of the joining energy, absence of process induced vibrations, imposing minimal thermal stress and avoiding particle generation. Furthermore this method exhibits high integration capabilities and automatization potential. Moreover, because of the current favorable cost development within the high power diode laser market laser welding of polymers has become more and more an industrially accepted joining method. This novel technology permits both, reliable high quality joining of mechanically and electronically highly sensitive micro components and hermetic sealing of macro components. There are different welding strategies available, which are adaptable to the current application. Within the frame of this discourse scientific and also application oriented results concerning laser transmission welding of polymers using preferably diode lasers are presented. Besides the used laser systems the fundamental process strategies as well as decisive process parameters are illustrated. The importance of optical, thermal and mechanical properties is discussed. Applications at real technical components will be presented, demonstrating the industrial implementation capability and the advantages of a novel technology.

  19. Enzyme-polymer composites with high biocatalytic activity and stability

    SciTech Connect

    Kim, Jungbae; Kosto, Timothy J.; Manimala, Joseph C.; Nauman, E B.; Dordick, Jonathan S.

    2004-08-22

    We have applied vacuum-spraying and electrospinning to incorporate an enzyme into a polymer matrix, creating a novel and highly active biocatalytic composite. As a unique technical approach, enzymes were co-dissolved in toluene with polymers, and the solvent was then rapidly removed by injecting the mixture into a vacuum chamber or by electrospinning. Subsequent crosslinking of the enzyme with glutaraldehyde resulted in stable entrapped enzyme within the polymeric matrices. For example, an amorphous composite of alpha-chymotrypsin and polyethylene showed no significant loss of enzymatic activity in aqueous buffer for one month. Nanofibers of alpha-chymotrypsin and polystyrene also showed no decrease in activity for more than two weeks. The normalized activity of amorphous composite in organic solvents was 3-13 times higher than that of native alpha-chymotrypsin. The activity of nanofibers was 5-7 times higher than that of amorphous composite in aqueous buffer solution. The composites of alpha-chymotrypsin and polymers demonstrate the feasibility of obtaining a wide variety of active and stable biocatalytic materials with many combinations of enzymes and polymers.

  20. Dynamic Monte Carlo simulation for highly efficient polymer blend photovoltaics.

    PubMed

    Meng, Lingyi; Shang, Yuan; Li, Qikai; Li, Yongfang; Zhan, Xiaowei; Shuai, Zhigang; Kimber, Robin G E; Walker, Alison B

    2010-01-14

    We developed a model system for blend polymers with electron-donating and -accepting compounds. It is found that the optimal energy conversion efficiency can be achieved when the feature size is around 10 nm. The first reaction method is used to describe the key processes (e.g., the generation, the diffusion, the dissociation at the interface for the excitons, the drift, the injection from the electrodes, and the collection by the electrodes for the charge carries) in the organic solar cell by the dynamic Monte Carlo simulation. Our simulations indicate that a 5% power conversion efficiency (PCE) is reachable with an optimum combination of charge mobility and morphology. The parameters used in this model study correspond to a blend of novel polymers (bis(thienylenevinylene)-substituted polythiophene and poly(perylene diimide-alt-dithienothiophene)), which features a broad absorption and a high mobility. The I-V curves are well-reproduced by our simulations, and the PCE for the polymer blend can reach up to 2.2%, which is higher than the experimental value (>1%), one of the best available experimental results up to now for the all-polymer solar cells. In addition, the dependency of PCE on the charge mobility and the material structure are also investigated. PMID:20000370

  1. High Temperature Polymers for use in Fuel Cells

    NASA Technical Reports Server (NTRS)

    Peplowski, Katherine M.

    2004-01-01

    NASA Glenn Research Center (GRC) is currently working on polymers for fuel cell and lithium battery applications. The desire for more efficient, higher power density, and a lower environmental impact power sources has led to interest in proton exchanges membrane fuels cells (PEMFC) and lithium batteries. A PEMFC has many advantages as a power source. The fuel cell uses oxygen and hydrogen as reactants. The resulting products are electricity, heat, and water. The PEMFC consists of electrodes with a catalyst, and an electrolyte. The electrolyte is an ion-conducting polymer that transports protons from the anode to the cathode. Typically, a PEMFC is operated at a temperature of about 80 C. There is intense interest in developing a fuel cell membrane that can operate at higher temperatures in the range of 80 C- 120 C. Operating the he1 cell at higher temperatures increases the kinetics of the fuel cell reaction as well as decreasing the susceptibility of the catalyst to be poisoned by impurities. Currently, Nafion made by Dupont is the most widely used polymer membrane in PEMFC. Nafion does not function well above 80 C due to a significant decrease in the conductivity of the membrane from a loss of hydration. In addition to the loss of conductivity at high temperatures, the long term stability and relatively high cost of Nafion have stimulated many researches to find a substitute for Nafion. Lithium ion batteries are popular for use in portable electronic devices, such as laptop computers and mobile phones. The high power density of lithium batteries makes them ideal for the high power demand of today s advanced electronics. NASA is developing a solid polymer electrolyte that can be used for lithium batteries. Solid polymer electrolytes have many advantages over the current gel or liquid based systems that are used currently. Among these advantages are the potential for increased power density and design flexibility. Automobiles, computers, and cell phones require

  2. Luminescent Solar Concentrators - a low cost photovoltaics alternative

    NASA Astrophysics Data System (ADS)

    van Sark, W. G. J. H. M.

    2012-10-01

    Luminescent solar concentrators (LSCs) are being developed as a potentially low cost-per-Wp photovoltaic device, suited for applications especially in the built environment. LSCs generally consist of transparent polymer sheets doped with luminescent species, either organic dye molecules or semiconductor nanocrystals. Direct and diffuse incident sunlight is absorbed by the luminescent species and emitted at redshifted wavelengths with high quantum efficiency. Optimum design ensures that a large fraction of emitted light is trapped in the sheet, which travels to the edges where it can be collected by one or more mono- or bifacial solar cells, with minimum losses due to absorption in the sheet and re-absorption by the luminescent species. Today's record efficieny is 7%, however, 10-15% is within reach. Optimized luminescent solar concentrators potentially offer lower cost per unit of power compared to conventional solar cells. Moreover, LSCs have an increased conversion efficiency for overcast and cloudy sky conditions, having a large fraction of diffuse irradiation, which is blueshifted compared to clear sky conditions. As diffuse irradiation conditions are omnipresent throughout mid- and northern-European countries, annual performance of LSCs is expected to be better in terms of kWh/Wp compared to conventional PV.

  3. Highly luminescent Sm(III) complexes with intraligand charge-transfer sensitization and the effect of solvent polarity on their luminescent properties.

    PubMed

    Lo, Wai-Sum; Zhang, Junhui; Wong, Wing-Tak; Law, Ga-Lai

    2015-04-20

    Samarium complexes with the highest quantum yields to date have been synthesized, and their luminescence properties were studied in 12 solvents. Sensitization via a nontriplet intraligand charge-transfer pathway was also successfully demonstrated in solution states with good quantum yields. PMID:25835302

  4. Polymers.

    ERIC Educational Resources Information Center

    Tucker, David C.

    1986-01-01

    Presents an open-ended experiment which has students exploring polymer chemistry and reverse osmosis. This activity involves construction of a polymer membrane, use of it in a simple osmosis experiment, and application of its principles in solving a science-technology-society problem. (ML)

  5. Self-assembly of doped semiconductor nanocrystals leading to the formation of highly luminescent nanorods

    NASA Astrophysics Data System (ADS)

    Manzoor, K.; Aditya, V.; Vadera, S. R.; Kumar, N.; Kutty, T. R. N.

    2006-03-01

    Meso-scale self-assembly of doped semiconductor nanocrystals leading to the formation of monocrystalline nanorods showing enhanced photo- and electro-luminescence properties are reported. Polycrystalline ZnS: Cu +-Al 3+ nanoparticles of zinc-blended (cubic) structure with an average size of ˜4 nm were aggregated in aqueous solution and grown into nanorods of length ˜400 nm and aspect ratio ˜12. Transmission electron microscope (TEM) images indicate crystal growth mechanisms involving particle-to-particle oriented-attachment assisted by sulphur-sulphur catenation leading to covalent-linkage. The nanorods exhibit self-assembly dependant luminescence properties such as quenching of the lattice defect-related emissions accompanied by enhancement of dopant-related emission, efficient low-voltage electroluminescence (EL) and super-linear voltage-brightness EL characteristics. This study demonstrates the technological importance of aggregation based self-assembly in doped semiconductor nanosystems.

  6. High Strain Rate Behavior of Polymer Matrix Composites Analyzed

    NASA Technical Reports Server (NTRS)

    Goldberg, Robert K.; Roberts, Gary D.

    2001-01-01

    Procedures for modeling the high-speed impact of composite materials are needed for designing reliable composite engine cases that are lighter than the metal cases in current use. The types of polymer matrix composites that are likely to be used in such an application have a deformation response that is nonlinear and that varies with strain rate. To characterize and validate material models that could be used in the design of impactresistant engine cases, researchers must obtain material data over a wide variety of strain rates. An experimental program has been carried out through a university grant with the Ohio State University to obtain deformation data for a representative polymer matrix composite for strain rates ranging from quasi-static to high rates of several hundred per second. This information has been used to characterize and validate a constitutive model that was developed at the NASA Glenn Research Center.

  7. High-performance hole transport layers for polymer light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Yan, He

    One key component in more advanced multilayer polymer light-emitting diode (PLED) structures is the hole transport layer (HTL). Conventional PLED conductive polymer HTLs exhibit serious drawbacks such as corrosion of anodes, significant absorption in visible region, and mediating oxidative doping of polyfluorene emissive layers (EMLs). In addition, the question still remains as to whether conventional PLED HTLs have the electron-blocking capacity required to achieve high-performance PLEDs. If not, the question arises as to how a PLED structure can be modified to afford greater electron-blocking at the HTL/EML interface. In the present thesis work, three generations of PLED HTLs were developed based on a siloxane-derivatized, crosslinkable, hole-transporting material, 4,4'-bis[(p-trichlorosilylpropylphenyl)phenylamino]biphenyl, TPDSi2. The first generation is the self-assembled monolayer (SAM) of TPDSi2, which can increase the work function of indium tin oxide (ITO) anode, enhance ITO anode hole injection, and hence improve PLED performance. The second generation is the spin-coated blend of TPDSi2 and a hole transporting polymer TFB on ITO, which forms an insoluble crosslinked network that can be used as a PLED HTL. The third generation is a double-layer HTL with the TPDSi2 + TFB on top of a conventional PLED HTL, which combines the hole injection capacity of conventional PLED HTLs and the electron-blocking capacity of the TPDSi2 + TFB blend. PLED devices based on these new HTLs exhibit comparable or superior performance compared to those based on conventional HTLs; high current efficiencies of ˜17 cd/A and maximum luminance of ˜140,000 cd/m2 have been achieved. These siloxane-based HTLs not only enhance PLED anode hole-injection by chemically bonding the HTL to the ITO anode, they also exhibit great electron-blocking capacity. The present organosiloxane HTL approach offers many other attractions such as convenience of fabrication, flexibility in choosing HTL

  8. Effect of concentration of anionic polymethine dye in poly-N-epoxypropylcarbazole polymer film composite on the spectral-luminescent properties and photoconductivity

    NASA Astrophysics Data System (ADS)

    Davidenko, Nikolay A.; Ishchenko, Alexander A.; Kulinich, Andrii V.; Studzinsky, Sergey L.

    2012-12-01

    The absorption, fluorescence and fluorescence excitation spectra of polymer thin film composites based on poly-N-epoxypropylcarbazole (PEPC) doped with different content of anionic polymethine dye testify to the formation of contact ion-pair associates at high concentration of the latter. The photoconductivity of such composites in the visible spectrum region is observed, despite the absence in the polymer of any fragment capable of accepting a photoexcited electron from anionic dye chromophore. Analysis of the spectral data together with DFT/B3LYP quantum-chemical calculation of the HOMO and LUMO energies of the monomer N-methylcarbazole unit and the radical of the polymethine dye allowed us to suggest the possible mechanism of internal photoeffect in the investigated composites which is based on the formation of the contact ion-pair associates.

  9. Effect of concentration of anionic polymethine dye in poly-N-epoxypropylcarbazole polymer film composite on the spectral-luminescent properties and photoconductivity.

    PubMed

    Davidenko, Nikolay A; Ishchenko, Alexander A; Kulinich, Andrii V; Studzinsky, Sergey L

    2012-12-01

    The absorption, fluorescence and fluorescence excitation spectra of polymer thin film composites based on poly-N-epoxypropylcarbazole (PEPC) doped with different content of anionic polymethine dye testify to the formation of contact ion-pair associates at high concentration of the latter. The photoconductivity of such composites in the visible spectrum region is observed, despite the absence in the polymer of any fragment capable of accepting a photoexcited electron from anionic dye chromophore. Analysis of the spectral data together with DFT/B3LYP quantum-chemical calculation of the HOMO and LUMO energies of the monomer N-methylcarbazole unit and the radical of the polymethine dye allowed us to suggest the possible mechanism of internal photoeffect in the investigated composites which is based on the formation of the contact ion-pair associates. PMID:22995470

  10. Developing Flexible, High Performance Polymers with Self-Healing Capabilities

    NASA Technical Reports Server (NTRS)

    Jolley, Scott T.; Williams, Martha K.; Gibson, Tracy L.; Caraccio, Anne J.

    2011-01-01

    Flexible, high performance polymers such as polyimides are often employed in aerospace applications. They typically find uses in areas where improved physical characteristics such as fire resistance, long term thermal stability, and solvent resistance are required. It is anticipated that such polymers could find uses in future long duration exploration missions as well. Their use would be even more advantageous if self-healing capability or mechanisms could be incorporated into these polymers. Such innovative approaches are currently being studied at the NASA Kennedy Space Center for use in high performance wiring systems or inflatable and habitation structures. Self-healing or self-sealing capability would significantly reduce maintenance requirements, and increase the safety and reliability performance of the systems into which these polymers would be incorporated. Many unique challenges need to be overcome in order to incorporate a self-healing mechanism into flexible, high performance polymers. Significant research into the incorporation of a self-healing mechanism into structural composites has been carried out over the past decade by a number of groups, notable among them being the University of I1linois [I]. Various mechanisms for the introduction of self-healing have been investigated. Examples of these are: 1) Microcapsule-based healant delivery. 2) Vascular network delivery. 3) Damage induced triggering of latent substrate properties. Successful self-healing has been demonstrated in structural epoxy systems with almost complete reestablishment of composite strength being achieved through the use of microcapsulation technology. However, the incorporation of a self-healing mechanism into a system in which the material is flexible, or a thin film, is much more challenging. In the case of using microencapsulation, healant core content must be small enough to reside in films less than 0.1 millimeters thick, and must overcome significant capillary and surface

  11. Thin polymer etalon arrays for high-resolution photoacoustic imaging

    PubMed Central

    Hou, Yang; Huang, Sheng-Wen; Ashkenazi, Shai; Witte, Russell; O’Donnell, Matthew

    2009-01-01

    Thin polymer etalons are demonstrated as high-frequency ultrasound sensors for three-dimensional (3-D) high-resolution photoacoustic imaging. The etalon, a Fabry-Perot optical resonator, consists of a thin polymer slab sandwiched between two gold layers. It is probed with a scanning continuous-wave (CW) laser for ultrasound array detection. Detection bandwidth of a 20-μm-diam array element exceeds 50 MHz, and the ultrasound sensitivity is comparable to polyvinylidene fluoride (PVDF) equivalents of similar size. In a typical photoacoustic imaging setup, a pulsed laser beam illuminates the imaging target, where optical energy is absorbed and acoustic waves are generated through the thermoelastic effect. An ultrasound detection array is formed by scanning the probing laser beam on the etalon surface in either a 1-D or a 2-D configuration, which produces 2-D or 3-D images, respectively. Axial and lateral resolutions have been demonstrated to be better than 20 μm. Detailed characterizations of the optical and acoustical properties of the etalon, as well as photoacoustic imaging results, suggest that thin polymer etalon arrays can be used as ultrasound detectors for 3-D high-resolution photoacoustic imaging applications. PMID:19123679

  12. HCN Polymers: Toward Structure Comprehension Using High Resolution Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Bonnet, Jean-Yves; Thissen, Roland; Frisari, Ma; Vuitton, Veronique; Quirico, Eric; Le Roy, Léna; Fray, Nicolas; Cottin, Hervé; Horst, Sarah; Yelle, Roger

    A lot of solar system materials, including cometary ices and Titan aerosols, contain dark matter that can be interpreted as complex nitrogen bearing organic matter [1]. In laboratory experi-ments, HCN polymers are thus analogs of great interest. In fact they may be present in Titan atmosphere and in comet nuclei and then reprocessed as a CN distributed source [2], when ices began to sublimate and ejects from the nucleus organic matter grains [3]. The presence of HCN polymers is suggested because HCN molecule has been directly observed in 1P/Halley comet [4] and others. HCN polymers are also of prebiotic interest [5] as it can form amino acid under hydrolysis conditions. Even if they have been studied during the last decades, their chemical composition and structure are still poorly understood, and a great analytical effort has to be continued. In this way we present a high resolution mass spectrometry (HRMS) and a high resolution tandem mass spectrometry (MS/HRMS) analysis of HCN polymers. It was shown [6] that this is a suitable technique to elucidate composition and structure of the soluble part of tholins analogs of Titan's atmosphere aerosols. HCN polymers have never been studied by HRMS, thus we used a LTQ-Orbitrap XL high resolution mass spectrometer to analyse the HCN polymers. These are produced at LISA by direct polymerisation of pure liquid HCN, catalyzed by ammonia. HCN polymers have been completely dissolved in methanol and then injected in the mass spectrometer by ElectroSpray Ionization (ESI). This atmospheric pressure ionization process produces protonated or deprotonated ions, but it does not fragment molecules. Thus HRMS, allows a direct access to the stoechiometry of all the ionizable molecules present in the samples. Fragmentation analyses (MS/MS) of selected ions have also been performed. Thess analysis provide information about the different chemical fonctionnalities present in HCN poly-mers and also about their structure. Thus we are able to

  13. Tough, high performance, addition-type thermoplastic polymers

    NASA Technical Reports Server (NTRS)

    Pater, Ruth H. (Inventor)

    1992-01-01

    A tough, high performance polyimide is provided by reacting a triple bond conjugated with an aromatic ring in a bisethynyl compound with the active double bond in a compound containing a double bond activated toward the formation of a Diels-Adler type adduct, especially a bismaleimide, a biscitraconimide, or a benzoquinone, or mixtures thereof. Addition curing of this product produces a high linear polymeric structure and heat treating the highly linear polymeric structure produces a thermally stable aromatic addition-type thermoplastic polyimide, which finds utility in the preparation of molding compounds, adhesive compositions, and polymer matrix composites.

  14. Single chain stochastic polymer modeling at high strain rates.

    SciTech Connect

    Harstad, E. N.; Harlow, Francis Harvey,; Schreyer, H. L.

    2001-01-01

    Our goal is to develop constitutive relations for the behavior of a solid polymer during high-strain-rate deformations. In contrast to the classic thermodynamic techniques for deriving stress-strain response in static (equilibrium) circumstances, we employ a statistical-mechanics approach, in which we evolve a probability distribution function (PDF) for the velocity fluctuations of the repeating units of the chain. We use a Langevin description for the dynamics of a single repeating unit and a Lioville equation to describe the variations of the PDF. Moments of the PDF give the conservation equations for a single polymer chain embedded in other similar chains. To extract single-chain analytical constitutive relations these equations have been solved for representative loading paths. By this process we discover that a measure of nonuniform chain link displacement serves this purpose very well. We then derive an evolution equation for the descriptor function, with the result being a history-dependent constitutive relation.

  15. Ultra-high molecular weight silphenylene-siloxane polymers

    NASA Technical Reports Server (NTRS)

    Patterson, W. J.; Hundley, N. H.; Ludwick, L. M.

    1984-01-01

    Silphenylene-siloxane copolymers with molecular weights above one million were prepared using a two stage polymerization technique. The technique was successfully scaled up to produce 50 grams of this high polymer in a single run. The reactive monomer approach was also investigated using the following aminosilanes: bis(dimethylamino)dimethylsilane, N,N-bis(pyrrolidinyl)dimethylsilane and N,N-bis(gamma-butyrolactam)dimethylsilane). Thermal analyses were performed in both air and nitrogen. The experimental polymers decomposed at 540 to 562 C, as opposed to 408 to 426 C for commercial silicones. Differential scanning calorimetry showed a glass transition (Tg) at -50 to -55 C for the silphenylene-siloxane copolymer while the commercial silicones had Tg's at -96 to -112 C.

  16. High-power polymer optical fiber amplifiers and their applications

    NASA Astrophysics Data System (ADS)

    Yamamoto, Tsuyoshi; Fujii, Kazuhito; Teramoto, Shigehiro; Tagaya, Akihiro; Nihei, Eisuke; Kinoshita, Takeshi; Koike, Yasuhiro; Sasaki, Keisuke

    1994-10-01

    Amplification characteristics of graded-index (GI) type organic dye doped polymer optical fiber amplifiers (POFAs) are discussed. As an organic dye for optical amplification, Rhodamine 6G, Rhodamine B, and Perylene Red are doped in the core region of polymer optical fibers (POFs). These POFA can obtain optical gain in the visible region of wavelength from 570 nm to 620 nm. POFA is promising for extraordinary high power optical amplification in comparison with rare-earth ions doped silica fiber amplifier. For example, output power of 1 kW with a gain of 30 dB can be obtained by using a Rhodamine B doped POFA at a low dye concentration of 1 ppm. Additionally, a novel solid-state POFA amplifier system is demonstrated.

  17. A convenient, high-throughput method for enzyme-luminescence detection of dopamine released from PC12 cells.

    PubMed

    Shinohara, Hiroaki; Wang, Feifei; Hossain, S M Zakir

    2008-01-01

    This protocol represents a novel enzyme-luminescence method to detect dopamine sensitively and rapidly with high temporal resolution. In principle, dopamine is first oxidized with tyramine oxidase to produce H(2)O(2), and then the produced H(2)O(2) reacts with luminol to generate chemiluminescence in the presence of horseradish peroxidase (POD). We applied this method successfully to perform real-time monitoring of dopamine release from PC12 cells using a luminescence plate reader upon stimulation with several drugs (e.g., acetylcholine, bradykinin). The results indicated that the dopamine release from PC12 cells was modulated by these drugs in a way similar to that found by using several conventional analytical techniques, such as HPLC-electrochemical detector (ECD). Unlike other assays, this assay technique is simple, rapid, highly sensitive and thus useful for assessment of effects of drugs on the nervous system. The dopamine release assay takes only < or =1 h once reagent setup and culture plates' preparation are finished. PMID:18833200

  18. Hydrothermal synthesis of highly luminescent blue-emitting ZnSe(S) quantum dots exhibiting low toxicity.

    PubMed

    Mirnajafizadeh, Fatemeh; Ramsey, Deborah; McAlpine, Shelli; Wang, Fan; Reece, Peter; Stride, John Arron

    2016-07-01

    Highly luminescent quantum dots (QDs) that emit in the visible spectrum are of interest to a number of imaging technologies, not least that of biological samples. One issue that hinders the application of luminescent markers in biology is the potential toxicity of the fluorophore. Here we show that hydrothermally synthesized ZnSe(S) QDs have low cytotoxicity to both human colorectal carcinoma cells (HCT-116) and human skin fibroblast cells (WS1). The QDs exhibited a high degree of crystallinity, with a strong blue photoluminescence at up to 29% quantum yield relative to 4',6-diamidino-2-phenylindole (DAPI) without post-synthetic UV-irradiation. Confocal microscopy images obtained of HCT-116 cells after incubation with the QDs highlighted the stability of the particles in cell media. Cytotoxicity studies showed that both HCT-116 and WS1 cells retain 100% viability after treatment with the QDs at concentrations up to 0.5g/L, which makes them of potential use in biological imaging applications. PMID:27127041

  19. High frequency electromagnetic interference shielding magnetic polymer nanocomposites

    NASA Astrophysics Data System (ADS)

    He, Qingliang

    Electromagnetic interference is one of the most concerned pollution and problem right now since more and more electronic devices have been extensively utilized in our daily lives. Besides the interference, long time exposure to electromagnetic radiation may also result in severe damage to human body. In order to mitigate the undesirable part of the electromagnetic wave energy and maintain the long term sustainable development of our modern civilized society, new technology development based researches have been made to solve this problem. However, one of the major challenges facing to the electromagnetic interference shielding is the relatively low shielding efficiency and the high cost as well as the complicated shielding material manufacture. From the materials science point of view, the key solutions to these challenges are strongly depended on the breakthrough of the current limit of shielding material design and manufacture (such as hierarchical material design with controllable and predictable arrangement in nanoscale particle configuration via an easy in-situ manner). From the chemical engineering point of view, the upgrading of advanced material shielding performance and the enlarged production scale for shielding materials (for example, configure the effective components in the shielding material in order to lower their usage, eliminate the "rate-limiting" step to enlarge the production scale) are of great importance. In this dissertation, the design and preparation of morphology controlled magnetic nanoparticles and their reinforced polypropylene polymer nanocomposites will be covered first. Then, the functionalities of these polymer nanocomposites will be demonstrated. Based on the innovative materials design and synergistic effect on the performance advancement, the magnetic polypropylene polymer nanocomposites with desired multifunctionalities are designed and produced targeting to the electromagnetic interference shielding application. In addition

  20. Enhanced luminescence excitation via efficient optical energy transfer (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Aad, Roy; Nomenyo, Komla D.; Bercu, Bogdan; Couteau, Christophe; Sallet, Vincent; Rogers, David J.; Molinari, Michael; Lérondel, Gilles

    2015-10-01

    Luminescent nanoscale materials (LNMs) have received widespread interest in sensing and lighting applications due to their enhanced emissive properties. For sensing applications, LNMs offer improved sensitivity and fast response time which allow for lower limits of detection. Meanwhile, for lighting applications, LNMs, such as quantum dots, offer an improved internal quantum efficiency and controlled color rendering which allow for better lighting performances. Nevertheless, due to their nanometric dimensions, nanoscale materials suffer from extremely weak luminescence excitation (i.e. optical absorption) limiting their luminescence intensity, which in turn results in a downgrade in the limits of detection and external quantum efficiencies. Therefore, enhancing the luminescence excitation is a major issue for sensing and lighting applications. In this work, we report on a novel photonic approach to increase the luminescence excitation of nanoscale materials. Efficient luminescence excitation increase is achieved via a gain-assisted waveguided energy transfer (G-WET). The G-WET concept consists on placing nanoscale materials atop of a waveguiding active (i.e. luminescent) layer with optical gain. Efficient energy transfer is thus achieved by exciting the nanoscale material via the tail of the waveguided mode of the active layer emission. The G-WET concept is demonstrated on both a nanothin layer of fluorescent sensitive polymer and on CdSe/ZnS quantum dots coated on ZnO thin film, experimentally proving up to an 8-fold increase in the fluorescence of the polymer and a 3-fold increase in the luminescence of the CdSe/ZnS depending of the active layer emission regime (stimulated vs spontaneous emission). Furthermore, we will discuss on the extended G-WET concept which consists on coating nanoscale materials on a nanostructured active layer. The nanostructured active layer offers the necessary photonic modulation and a high specific surface which can presumably lead to

  1. Optically stimulated luminescence and thermoluminescence efficiencies for high-energy heavy charged particle irradiation in Al2O3:C

    NASA Technical Reports Server (NTRS)

    Yukihara, E. G.; Gaza, R.; McKeever, S. W. S.; Soares, C. G.

    2004-01-01

    The thermally and optically stimulated luminescence (TL and OSL) response to high energy heavy-charged particles (HCPs) was investigated for two types of Al2O3:C luminescence dosimeters. The OSL signal was measured in both continuous-wave (CW) and pulsed mode. The efficiencies of the HCPs at producing TL or OSL, relative to gamma radiation, were obtained using four different HCPs beams (150 MeV/u 4He, 400 MeV/u 12C, 490 MeV/u 28Si, and 500 MeV/u 56Fe). The efficiencies were determined as a function of the HCP linear energy transfer (LET). It was observed that the efficiency depends on the type of detector, measurement technique, and the choice of signal. Additionally, it is shown that the shape of the CW-OSL decay curve from Al2O3:C depends on the type of radiation, and, in principle, this can be used to extract information concerning the LET of an unknown radiation field. The response of the dosimeters to low-LET radiation was also investigated for doses in the range from about 1-1000 Gy. These data were used to explain the different efficiency values obtained for the different materials and techniques, as well as the LET dependence of the CW-OSL decay curve shape. c2003 Elsevier Ltd. All rights reserved.

  2. Optically stimulated luminescence and thermoluminescence efficiencies for high-energy heavy charged particle irradiation in Al2O3:C.

    PubMed

    Yukihara, E G; Gaza, R; McKeever, S W S; Soares, C G

    2004-02-01

    The thermally and optically stimulated luminescence (TL and OSL) response to high energy heavy-charged particles (HCPs) was investigated for two types of Al2O3:C luminescence dosimeters. The OSL signal was measured in both continuous-wave (CW) and pulsed mode. The efficiencies of the HCPs at producing TL or OSL, relative to gamma radiation, were obtained using four different HCPs beams (150 MeV/u 4He, 400 MeV/u 12C, 490 MeV/u 28Si, and 500 MeV/u 56Fe). The efficiencies were determined as a function of the HCP linear energy transfer (LET). It was observed that the efficiency depends on the type of detector, measurement technique, and the choice of signal. Additionally, it is shown that the shape of the CW-OSL decay curve from Al2O3:C depends on the type of radiation, and, in principle, this can be used to extract information concerning the LET of an unknown radiation field. The response of the dosimeters to low-LET radiation was also investigated for doses in the range from about 1-1000 Gy. These data were used to explain the different efficiency values obtained for the different materials and techniques, as well as the LET dependence of the CW-OSL decay curve shape. PMID:14672096

  3. Highly efficient luminescence of Cu(I) compounds: thermally activated delayed fluorescence combined with short-lived phosphorescence.

    PubMed

    Hofbeck, Thomas; Monkowius, Uwe; Yersin, Hartmut

    2015-01-14

    Luminescent materials showing thermally activated delayed fluorescence (TADF) have gained high attractiveness as emitters in organic light emitting diodes (OLEDs) and other photonic applications. Nevertheless, even utilization of TADF can be further improved, introducing a novel concept. This is demonstrated by a new class of brightly luminescent low-cost Cu(I) compounds, for which the emission stems from both the lowest excited triplet T1 and singlet S1 state. At T = 300 K, these materials exhibit quantum yields of more than ΦPL = 90% at short emission decay times. About 80% of the emission intensity stems from the singlet due to TADF, but importantly, an additional 20% is contributed by the lower lying triplet state according to effective spin-orbit coupling (SOC). SOC induces also a relatively large zero-field splitting of the triplet being unusual for Cu(I) complexes. Thus, the overall emission decay time is distinctly reduced. Combined use of both decay paths opens novel photonic applications, in particular, for OLEDs. PMID:25486064

  4. Fabrication and characterization of highly luminescent Er3+:Al2O3 thin films with optimized growth parameters

    NASA Astrophysics Data System (ADS)

    Nayar, Priyanka; Zhu, Xue-Yi; Yang, Fuyi; Lu, Minghui; Lakshminarayana, G.; Liu, Xiao Ping; Chen, Yan-Feng; Kityk, I. V.

    2016-10-01

    Erbium doped amorphous alumina thin films were fabricated using Co-sputtering technique in various depositions runs with varying parameters for optimizing the deposition parameters to obtain the films with best optical performance. The main subject of investigation includes the effects of change in various deposition parameters such as substrate heating, radio frequency (RF) power and oxygen pressure inside the chamber while deposition. High quality as-deposited films with various Er concentrations and low carbon content have been confirmed by XPS. Substrate heating ∼500 °C was found to be very effective in getting highly dense films with high refractive index of 1.70 at 1530-1570 nm emission band. The Er3+-doped films showed very intense near-infrared luminescence peak at 1550 nm even without any post-deposition annealing treatment.

  5. Selective phase synthesis of a high luminescence Gd2O3:Eu nanocrystal phosphor through direct solution combustion.

    PubMed

    Xia, Guodong; Wang, Sumei; Zhou, Shengming; Xu, Jun

    2010-08-27

    A Gd(2)O(3):Eu nanocrystal phosphor has been directly synthesized by a mild solution combustion method with a single step approach while avoiding further thermal annealing. The as-combusted Gd(2)O(3):Eu powders have been characterized by x-ray diffraction, infrared spectroscopy, transmission electron microscopy and photoluminescence spectra. The ratio of citric acid to metal nitrate (C/M) has a critical impact on the phase composition and crystallization of as-combusted Gd(2)O(3):Eu. An optimal C/M ratio of 0.7 gave highly crystalline powders with a single cubic phase, and a high luminescence intensity comparable with that of a commercial Y(2)O(3):Eu phosphor, even without further thermal annealing. This direct solution combustion method can be used to prepare a variety of high quality oxide nanocrystals. PMID:20671360

  6. Independent Composition and Size Control for Highly Luminescent Indium-Rich Silver Indium Selenide Nanocrystals.

    PubMed

    Yarema, Olesya; Yarema, Maksym; Bozyigit, Deniz; Lin, Weyde M M; Wood, Vanessa

    2015-11-24

    Ternary I-III-VI nanocrystals, such as silver indium selenide (AISe), are candidates to replace cadmium- and lead-based chalcogenide nanocrystals as efficient emitters in the visible and near IR, but, due to challenges in controlling the reactivities of the group I and III cations during synthesis, full compositional and size-dependent behavior of I-III-VI nanocrystals is not yet explored. We report an amide-promoted synthesis of AISe nanocrystals that enables independent control over nanocrystal size and composition. By systematically varying reaction time, amide concentration, and Ag- and In-precursor concentrations, we develop a predictive model for the synthesis and show that AISe sizes can be tuned from 2.4 to 6.8 nm across a broad range of indium-rich compositions from AgIn11Se17 to AgInSe2. We perform structural and optical characterization for representative AISe compositions (Ag0.85In1.05Se2, Ag3In5Se9, AgIn3Se5, and AgIn11Se17) and relate the peaks in quantum yield to stoichiometries exhibiting defect ordering in the bulk. We optimize luminescence properties to achieve a record quantum yield of 73%. Finally, time-resolved photoluminescence measurements enable us to better understand the physics of donor-acceptor emission and the role of structure and composition in luminescence. PMID:26370776

  7. Highly Enhanced Cooperative Upconversion Luminescence through Energy Transfer Optimization and Quenching Protection.

    PubMed

    Xue, Meng; Zhu, Xingjun; Qiu, Xiaochen; Gu, Yuyang; Feng, Wei; Li, Fuyou

    2016-07-20

    Upconversion luminescence nanomaterials have shown great potential in biological and physical applications because of their unique properties. However, limited research exists on the cooperative sensitization upconversion emission in Tb(3+) ions over Er(3+) ions and Tm(3+) ions because of its low efficiency. Herein, by optimizing the doping ratio of sensitizer and activator to maximize the utilization of the photon energy and introducing the CaF2 inert shell to shield sensitizer from quenchers, we synthesize ultrasmall NaYbF4:Tb@CaF2 nanoparticles with a significant enhancement (690-fold) in cooperative sensitization upconversion emission intensity, compared with the parent NaYbF4:Tb. The lifetime of Tb(3+) emission in NaYbF4:Tb@CaF2 nanoparticles is prolonged extensively to ∼3.5 ms. Furthermore, NaYbF4:Tb@CaF2 was applied in in vitro and in vivo bioimaging. The presented luminescence enhancement strategy provides cooperative sensitization upconversion with new opportunities for bioapplication. PMID:27347810

  8. Highly enhanced luminescence of nanocrystalline TiO 2:Eu 3+ phosphors

    NASA Astrophysics Data System (ADS)

    Yi, Soung-soo; Bae, Jong Seong; Moon, Byung Kee; Jeong, Jung Hyun; Kim, Jung Hwan

    2006-05-01

    Narrow-dispersed nanocrystalline TiO 2:Eu 3+ phosphors have been synthesized by reverse micelles and solvothermal synthetic method in toluene solutions. Different concentrations of europium nitrate pentahydrate (5.0, 10.0, 20.0 and 25.0 mol%) were dissolved in water. After the solution was thermally treated at 250 °C for 20 h in an autoclave, low-dispersed TiO 2:Eu 3+ nanocrystalline particles with average size of <5 nm were synthesized. The nanocomposites were composed nominally of TiO 2 shell with Eu 2O 3 core. The crystalline phase and microstructure of the nanoparticles were investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. Also, luminescent spectra and composition ratio were measured using luminescent spectrometer and energy dispersive X-ray spectrometer. The radiation was dominated by the red emission peak at 616 nm and the highest emission intensity was observed with TiO 2:Eu 0.2, whose brightness was increased by a factor of 1.9 in comparison with that of TiO 2:Eu 0.05. The photoluminescence and excitation spectra show similar behavior as a function of Eu concentration.

  9. Synthesis, characterization and luminescent properties of europium complexes with 2,4,6-tris-(2-pyridyl)-s-triazine as highly efficient sensitizers.

    PubMed

    Kang, Jie; Chen, Ying-Nan; Wang, Ai-Ling; Li, Hai-Yan; Qu, Yan-Rong; Zhang, Hai-Xia; Chu, Hai-Bin; Zhao, Yong-Liang

    2015-12-01

    Using 2,4,6-tris-(2-pyridyl)-s-triazine (TPTZ) as a neutral ligand, and p-hydroxybenzoic acid, terephthalic acid and nitrate as anion ligands, five novel europium complexes have been synthesized. These complexes were characterized using elemental analysis, rare earth coordination titrations, UV/vis absorption spectroscopy and infrared spectroscopy. Luminescence spectra, luminescence lifetime and quantum efficiency were investigated and the mechanism discussed in depth. The results show that the complexes have excellent emission intensities, long emission lifetimes and high quantum efficiencies. The superior luminescent properties of the complexes may be because the triplet energy level of the ligands matches well with the lowest excitation state energy level of Eu(3+). Moreover, changing the ratio of the ligands and metal ions leads to different luminescent properties. Among the complexes, Eu2(TPTZ)2(C8H4O4)(NO3)4(C2H5OH)·H2O shows the strongest luminescence intensity, longest emission lifetime and highest quantum efficiency. PMID:25829339

  10. Luminescent nanocrystal stress gauge

    PubMed Central

    Choi, Charina L.; Koski, Kristie J.; Olson, Andrew C. K.; Alivisatos, A. Paul

    2010-01-01

    Microscale mechanical forces can determine important outcomes ranging from the site of material fracture to stem cell fate. However, local stresses in a vast majority of systems cannot be measured due to the limitations of current techniques. In this work, we present the design and implementation of the CdSe-CdS core-shell tetrapod nanocrystal, a local stress sensor with bright luminescence readout. We calibrate the tetrapod luminescence response to stress and use the luminescence signal to report the spatial distribution of local stresses in single polyester fibers under uniaxial strain. The bright stress-dependent emission of the tetrapod, its nanoscale size, and its colloidal nature provide a unique tool that may be incorporated into a variety of micromechanical systems including materials and biological samples to quantify local stresses with high spatial resolution. PMID:21098301

  11. Response of polymer composites to high and low velocity impact

    NASA Technical Reports Server (NTRS)

    Hsieh, C. Y.; Mount, A.; Jang, B. Z.; Zee, R. H.

    1990-01-01

    The present investigation of fiber-reinforced polymer matrix composites' impact characteristics employed a drop tower for the low-velocity impact case and a novel, projectile instantaneous velocity-measuring sensor for high-velocity impact. Attention was given to the energy loss of projectiles in composites reinforced with polyethylene, kevlar, and graphite. Two distinct energy-loss mechanisms are noted, the first of which is due to the actual fracture process while the other is due to the generation of friction heat. The drop-tower impact-test results furnish the strain-rate dependence of the energy loss.

  12. Polymer mud system maintains high ROP in deep well

    SciTech Connect

    Palm, J.D. )

    1994-10-24

    The use of a polymer mud system with low plastic viscosity helped reduce the drilling time on a deep well in Oklahoma. An aggressive bit program and the special mud system, which kept low-gravity solids to a minimum, kept the rate of penetration (ROP) high in the deeper sections of the well. The Montgomery No. 3-A well, located in section 3-6N-9W in Caddo County, Okla., reached total depth of 18,345 ft in 106 days for less than $1.6 million, which was quicker and less expensive than offset wells. The drilling of this well is detailed.

  13. High-Voltage Solid Polymer Batteries for Electric Drive Vehicles

    SciTech Connect

    Eitouni, Hany; Yang, Jin; Pratt, Russell; Wang, Xiao; Grape, Ulrik

    2014-09-29

    The purpose of this project was for Seeo to develop a high energy lithium based technology with targets of over 500 Wh/l and 325 Wh/kg. Seeo would leverage the work already achieved with its unique proprietary solid polymer DryLyteTM technology in cells which had a specific energy density of 220 Wh/kg. The development work was focused on establishing a dual electrolyte system, coated cathode particle techniques, various types of additives, and different conductive salts. The program had a duration of three years, with Seeo delivering the final cells at the end of 2014 for evaluation by a DOE laboratory.

  14. Ladder polymers for use as high temperature stable resins or coatings

    NASA Technical Reports Server (NTRS)

    Meador, Mary Ann (Inventor)

    1990-01-01

    An object of the invention is to synthesize a new class of ladder and partial ladder polymers. In accordance with the invention, the new class of ladder and partial ladder polymers are synthesized by polymerizing a bis-dienophile with a bis-diene. Another object of the invention is to provide a fabricated, electrically conducting, void free composite comprising the new class of the ladder and partial ladder polymers described above. The novelty of the invention relates to a new class of ladder and partial ladder polymers and a process for synthesizing these polymers. These polymers are soluble in common organic solvents and are characterized with a unique dehydration property at temperatures of 300 to 400 C to provide thermo-oxidatively stable pentiptycene units along the polymeric backbone. These polymers are further characterized with high softening points and good thermo-oxidative stability properties. Thus these polymers have potential as processable, matrix resins for high temperature composite applications.

  15. Shape memory polymers with high and low temperature resistant properties

    PubMed Central

    Xiao, Xinli; Kong, Deyan; Qiu, Xueying; Zhang, Wenbo; Liu, Yanju; Zhang, Shen; Zhang, Fenghua; Hu, Yang; Leng, Jinsong

    2015-01-01

    High temperature shape memory polymers that can withstand the harsh temperatures for durable applications are synthesized, and the aromatic polyimide chains with flexible linkages within the backbone act as reversible phase. High molecular weight (Mn) is demanded to form physical crosslinks as fixed phase of thermoplastic shape memory polyimide, and the relationship between Mn and glass transition temperature (Tg) is explored. Thermoset shape memory polyimide shows higher Tg and storage modulus, better shape fixity than thermoplastic counterpart due to the low-density covalent crosslinking, and the influence of crosslinking on physical properties are studied. The mechanism of high temperature shape memory effects based on chain flexibility, molecular weight and crosslink density is proposed. Exposure to thermal cycling from +150 °C to −150 °C for 200 h produces negligible effect on the properties of the shape memory polyimide, and the possible mechanism of high and low temperature resistant property is discussed. PMID:26382318

  16. Shape memory polymers with high and low temperature resistant properties

    NASA Astrophysics Data System (ADS)

    Xiao, Xinli; Kong, Deyan; Qiu, Xueying; Zhang, Wenbo; Liu, Yanju; Zhang, Shen; Zhang, Fenghua; Hu, Yang; Leng, Jinsong

    2015-09-01

    High temperature shape memory polymers that can withstand the harsh temperatures for durable applications are synthesized, and the aromatic polyimide chains with flexible linkages within the backbone act as reversible phase. High molecular weight (Mn) is demanded to form physical crosslinks as fixed phase of thermoplastic shape memory polyimide, and the relationship between Mn and glass transition temperature (Tg) is explored. Thermoset shape memory polyimide shows higher Tg and storage modulus, better shape fixity than thermoplastic counterpart due to the low-density covalent crosslinking, and the influence of crosslinking on physical properties are studied. The mechanism of high temperature shape memory effects based on chain flexibility, molecular weight and crosslink density is proposed. Exposure to thermal cycling from +150 °C to -150 °C for 200 h produces negligible effect on the properties of the shape memory polyimide, and the possible mechanism of high and low temperature resistant property is discussed.

  17. A high performance ceramic-polymer separator for lithium batteries

    NASA Astrophysics Data System (ADS)

    Kumar, Jitendra; Kichambare, Padmakar; Rai, Amarendra K.; Bhattacharya, Rabi; Rodrigues, Stanley; Subramanyam, Guru

    2016-01-01

    A three-layered (ceramic-polymer-ceramic) hybrid separator was prepared by coating ceramic electrolyte [lithium aluminum germanium phosphate (LAGP)] over both sides of polyethylene (PE) polymer membrane using electron beam physical vapor deposition (EB-PVD) technique. Ionic conductivities of membranes were evaluated after soaking PE and LAGP/PE/LAGP membranes in a 1 Molar (1M) lithium hexafluroarsenate (LiAsF6) electrolyte in ethylene carbonate (EC), dimethyl carbonate (DMC) and ethylmethyl carbonate (EMC) in volume ratio (1:1:1). Scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques were employed to evaluate morphology and structure of the separators before and after cycling performance tests to better understand structure-property correlation. As compared to regular PE separator, LAGP/PE/LAGP hybrid separator showed: (i) higher liquid electrolyte uptake, (ii) higher ionic conductivity, (iii) lower interfacial resistance with lithium and (iv) lower cell voltage polarization during lithium cycling at high current density of 1.3 mA cm-2 at room temperature. The enhanced performance is attributed to higher liquid uptake, LAGP-assisted faster ion conduction and dendrite prevention. Optimization of density and thickness of LAGP layer on PE or other membranes through manipulation of PVD deposition parameters will enable practical applications of this novel hybrid separator in rechargeable lithium batteries with high energy, high power, longer cycle life, and higher safety level.

  18. Hierarchical nanostructured conducting polymer hydrogel with high electrochemical activity

    PubMed Central

    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

    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 μA·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

  19. Spectral fingerprinting of polycyclic aromatic hydrocarbons in high-volume ambient air samples by constant energy synchronous luminescence spectroscopy

    USGS Publications Warehouse

    Kerkhoff, M.J.; Lee, T.M.; Allen, E.R.; Lundgren, D.A.; Winefordner, J.D.

    1985-01-01

    A high-volume sampler fitted with a glass-fiber filter and backed by polyurethane foam (PUF) was employed to collect airborne particulate and gas-phase polycylic aromatic hydrocarbons (PAHs) in ambient air. Samples were collected from four sources representing a range of environmental conditions: gasoline engine exhaust, diesel engine exhaust, air near a heavily traveled interstate site, and air from a moderately polluted urban site. Spectral fingerprints of the unseparated particulate and gas-phase samples were obtained by constant energy synchronous luminescence spectroscopy (CESLS). Five major PAHs in the gas-phase extracts were characterized and estimated. The compatibility of a high-volume sampling method using polyurethane foam coupled with CESLS detection is explored for use as a screening technique for PAHs in ambient air. ?? 1985 American Chemical Society.

  20. Highly luminescent undoped and Mn-doped ZnS nanoparticles by liquid phase pulsed laser ablation

    NASA Astrophysics Data System (ADS)

    Aneesh, P. M.; Shijeesh, M. R.; Aravind, Arun; Jayaraj, M. K.

    2014-09-01

    In this paper we report the synthesis of highly luminescent ZnS and Mn-doped ZnS nanoparticles with uniform particle size distribution by liquid phase pulsed laser ablation. The formation of nanosized ZnS crystallites was confirmed by high-resolution transmission electron microscopy (HRTEM) images. The optical properties of these nanoparticles were studied by room temperature photoluminescence (PL) spectra. The PL emission from the ZnS nanoparticles shows a sharp peak in the UV region (334 nm) corresponding to the band edge and a broad peak in the visible region which can be attributed to the sulphur vacancies, cation vacancies and surface states in the nanocrystals. The yellow emission from the Mn-doped ZnS nanoparticles can be attributed to the radiative transition between 4T1 and 6A1 levels within the 3d5 orbital of Mn2+.

  1. High solid-state luminescence in propeller-shaped AIE-active pyridine-ketoiminate-boron complexes.

    PubMed

    Wu, Yanping; Li, Zhenyu; Liu, Qingsong; Wang, Xiaoqing; Yan, Hui; Gong, Shuwen; Liu, Zhipeng; He, Weijiang

    2015-05-28

    Two pyridine-ketoiminate-based organoboron complexes (2 and 3) were developed. 2 and 3 showed very weak emission in low-viscosity organic solvents because of the intramolecular rotation induced non-radiative process. Their emission can be dramatically enhanced by the increase in solvent viscosity or by molecular aggregation in the solid state. Moreover, 2 and 3 exhibited intense emission with high quantum yield of 0.53 and 0.46, respectively. X-ray crystallographic analysis showed that the weak intermolecular interactions such as C-H···F and C-H···π by fixing the molecular conformations of 2 and 3 were responsible for intense luminescence in the solid state. The large Stokes shifts and high efficient solid-state emission of 2 and 3 make them valuable AIE luminophores for further potential applications in the fields of fluorescence imaging and materials science. PMID:25906250

  2. Highly luminescent water-soluble quaternary Zn-Ag-In-S quantum dots for tumor cell-targeted imaging.

    PubMed

    Deng, Dawei; Cao, Jie; Qu, Lingzhi; Achilefu, Samuel; Gu, Yueqing

    2013-04-14

    Exploring the synthesis and biomedical applications of biocompatible quantum dots (QDs) is currently one of the fastest growing fields of nanotechnology. Hence, in this work, we present a facile approach to produce water-soluble (cadmium-free) quaternary Zn-Ag-In-S (ZAIS) QDs. Their efficient photoluminescence (PL) emissions can be tuned widely in the range of 525-625 nm by controlling the size and composition of the QDs with the PL quantum yields (QYs) of 15-30%. These highly luminescent ZAIS QDs are less toxic due to the absence of highly toxic cadmium, and can be versatilely modified by a DHLA-PEG-based ligand. Importantly, after being modified by tumor cell-specific targeting ligands (e.g., folate and RGD peptide), the PEGylated quaternary QDs show potential applications in tumor cell imaging as a promising alternative for Cd-based QDs. PMID:23450151

  3. Self-Assembling Peptide Coatings Designed for Highly Luminescent Suspension of Single-Walled Carbon Nanotubes

    PubMed Central

    Tsyboulski, Dmitri A.; Bakota, Erica L.; Witus, Leah S.; Rocha, John-David R.; Hartgerink, Jeffrey D.; Weisman, R. Bruce

    2009-01-01

    A series of self-assembling multidomain peptides have been designed, synthesized, and tested for their ability to individually suspend single-walled carbon nanotubes (SWCNTs) in water while preserving strong near-IR nanotube luminescence. Photometric and spectral measurements on individual SWCNTs revealed that emission in the common biocompatible coating agents Pluronic F127, ss-DNA, and BSA is approximately an order of magnitude weaker than in the bio-incompatible ionic surfactant SDBS. By contrast, one of the engineered peptides gave SWCNT emission ~40% as intense as in SDBS. A strong inverse correlation was also found between the spectral line widths of coated SWCNTs and the efficiency of their emission. Peptides with rationally designed self-assembly properties appear to be promising coatings that may enable SWCNT optical sensing applications in biological environments. PMID:19053447

  4. Photoconductive Cathode Interlayer for Highly Efficient Inverted Polymer Solar Cells.

    PubMed

    Nian, Li; Zhang, Wenqiang; Zhu, Na; Liu, Linlin; Xie, Zengqi; Wu, Hongbin; Würthner, Frank; Ma, Yuguang

    2015-06-10

    A highly photoconductive cathode interlayer was achieved by doping a 1 wt % light absorber, such as perylene bisimide, into a ZnO thin film, which absorbs a very small amount of light but shows highly increased conductivity of 4.50 × 10(-3) S/m under sunlight. Photovoltaic devices based on this kind of photoactive cathode interlayer exhibit significantly improved device performance, which is rather insensitive to the thickness of the cathode interlayer over a broad range. Moreover, a power conversion efficiency as high as 10.5% was obtained by incorporation of our photoconductive cathode interlayer with the PTB7-Th:PC71BM active layer, which is one of the best results for single-junction polymer solar cells. PMID:26016386

  5. Environmentally Friendly Mechanochemical Syntheses and Conversions of Highly Luminescent Cu(I) Dinuclear Complexes.

    PubMed

    Kobayashi, Atsushi; Hasegawa, Tatsuya; Yoshida, Masaki; Kato, Masako

    2016-03-01

    Luminescent dinuclear Cu(I) complexes, [Cu2X2(dpypp)2] [Cu-X; X = Cl, Br, I; dpypp = 2,2'-(phenylphosphinediyl)dipyridine], were successfully synthesized by a solvent-assisted mechanochemical method. A trace amount of the assisting solvent plays a key role in the mechanochemical synthesis; only two solvents possessing the nitrile group, CH3CN and PhCN, were effective for promoting the formation of dinuclear Cu-X. X-ray analysis revealed that the dinuclear structure with no Cu···Cu interactions, bridged by two dpypp ligands, was commonly formed in all Cu-X species. These complexes exhibited bright green emission in the solid state at room temperature (Φ = 0.23, 0.50, and 0.74; λem = 528, 518, and 530 nm for Cu-Cl, Cu-Br, and Cu-I, respectively). Emission decay measurement and TD-DFT calculation suggested that the luminescence of Cu-X could be assigned to phosphorescence from the triplet metal-to-ligand charge-transfer ((3)MLCT) excited state, effectively mixed with the halide-to-ligand charge-transfer ((3)XLCT) excited state, at 77 K. The source of emission changed to thermally activated delayed fluorescence (TADF) with the same electronic transition nature at room temperature. In addition, the CH3CN-bound analogue, [Cu2(CH3CN)2(dpypp)2](BF4)2, was successfully mechanochemically converted to Cu-X by grinding with solid KX in the presence of a trace amount of assisting water. PMID:26866384

  6. Detection of Waterborne Viruses Using High Affinity Molecularly Imprinted Polymers.

    PubMed

    Altintas, Zeynep; Gittens, Micah; Guerreiro, Antonio; Thompson, Katy-Anne; Walker, Jimmy; Piletsky, Sergey; Tothill, Ibtisam E

    2015-07-01

    Molecularly imprinted polymers (MIPs) are artificial receptor ligands which can recognize and specifically bind to a target molecule. They are more resistant to chemical and biological damage and inactivation than antibodies. Therefore, target specific-MIP nanoparticles are aimed to develop and implemented to biosensors for the detection of biological toxic agents such as viruses, bacteria, and fungi toxins that cause many diseases and death due to the environmental contamination. For the first time, a molecularly imprinted polymer (MIP) targeting the bacteriophage MS2 as the template was investigated using a novel solid-phase synthesis method to obtain the artificial affinity ligand for the detection and removal of waterborne viruses through optical-based sensors. A high affinity between the artificial ligand and the target was found, and a regenerative MIP-based virus detection assay was successfully developed using a new surface plasmon resonance (SPR)-biosensor which provides an alternative technology for the specific detection and removal of waterborne viruses that lead to high disease and death rates all over the world. PMID:26008649

  7. Surprising high hydrophobicity of polymer networks from hydrophilic components.

    PubMed

    Attanasio, Agnese; Bayer, Ilker S; Ruffilli, Roberta; Ayadi, Farouk; Athanassiou, Athanassia

    2013-06-26

    We report a simple and inexpensive method of fabricating highly hydrophobic novel materials based on interpenetrating networks of polyamide and poly(ethyl cyanoacrylate) hydrophilic components. The process is a single-step solution casting from a common solvent, formic acid, of polyamide and ethyl cyanoacrylate monomers. After casting and subsequent solvent evaporation, the in situ polymerization of ethyl cyanoacrylate monomer forms polyamide-poly(ethyl cyanoacrylate) interpenetrating network films. The interpenetrating networks demonstrate remarkable waterproof properties allowing wettability control by modulating the concentration of the components. In contrast, pure polyamide and poly(ethyl cyanoacrylate) films obtained from formic acid solutions are highly hygroscopic and hydrophilic, respectively. The polymerization of ethyl cyanoacrylate in the presence of polyamide promotes molecular interactions between the components, which reduce the available hydrophilic moieties and render the final material hydrophobic. The wettability, morphology, and thermo-physical properties of the polymeric coatings were characterized. The materials developed in this work take advantage of the properties of both polymers in a single blend and above all, due to their hydrophobic nature and minimal water uptake, can extend the application range of the individual polymers where water repellency is required. PMID:23713478

  8. Polymer Microarrays for High Throughput Discovery of Biomaterials

    PubMed Central

    Hook, Andrew L.; Chang, Chien-Yi; Yang, Jing; Scurr, David J.; Langer, Robert; Anderson, Daniel G.; Atkinson, Steve; Williams, Paul; Davies, Martyn C.; Alexander, Morgan R.

    2012-01-01

    The discovery of novel biomaterials that are optimized for a specific biological application is readily achieved using polymer microarrays, which allows a combinatorial library of materials to be screened in a parallel, high throughput format1. Herein is described the formation and characterization of a polymer microarray using an on-chip photopolymerization technique 2. This involves mixing monomers at varied ratios to produce a library of monomer solutions, transferring the solution to a glass slide format using a robotic printing device and curing with UV irradiation. This format is readily amenable to many biological assays, including stem cell attachment and proliferation, cell sorting and low bacterial adhesion, allowing the ready identification of 'hit' materials that fulfill a specific biological criterion3-5. Furthermore, the use of high throughput surface characterization (HTSC) allows the biological performance to be correlated with physio-chemical properties, hence elucidating the biological-material interaction6. HTSC makes use of water contact angle (WCA) measurements, atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). In particular, ToF-SIMS provides a chemically rich analysis of the sample that can be used to correlate the cell response with a molecular moiety. In some cases, the biological performance can be predicted from the ToF-SIMS spectra, demonstrating the chemical dependence of a biological-material interaction, and informing the development of hit materials5,3. PMID:22314927

  9. High-Temperature NMR Studies of Quasicrystals and Polymers

    NASA Astrophysics Data System (ADS)

    Hill, Edward Arthur

    1995-01-01

    Icosahedral alloys such as rm Al _{65}Cu_{20}Ru_ {15}, Al_{62.5}Cu_ {24.5}Fe_{13}, and rm Al_{70}Pd_{20}Re _{10} have motivated a great deal of experimental and theoretical effort to understand fundamental issues such as the electronic structure, "lattice" dynamics, and thermodynamic stability of quasicrystalline materials. It has been shown here that Nuclear Magnetic Resonance (NMR) is a useful tool for exploring many of the essential properties of quasicrystal alloys and the so-called approximant phase alloys. Specifically, the ^{27 }Al Knight shift has been used here to study the electronic density of states in these alloys up to temperatures of 1200 K. Furthermore, ^{27}Al nuclear spin-lattice and spin-spin relaxation measurements across a wide temperature range have been used to show that the dynamic processes found in quasicrystals are quite different from those found in some crystalline alloys of similar compositions. In addition, two-dimensional exchange experiments have been employed to study the dynamics of these materials. Finally, the semiconducting alloy rm Al_2Ru has also been studied by the techniques mentioned above. It has also been demonstrated here that high temperature NMR techniques are useful in the study of organic polymers. These experiments focus on determining the timescales and other aspects of molecular motion for several specific samples. ^2H NMR measurements, including the ^2H two-dimensional exchange technique, on the high temperature polymer polybenzamidazole (PBI) are described here. ^2H NMR results for high melting temperature copolyester liquid crystals of the PCnNBB family will also be discussed. An assessment of the high temperature motion in these samples is relevant to an understanding of the physical properties that influence their high temperature applications and high temperature processing.

  10. A robust and luminescent covalent organic framework as a highly sensitive and selective sensor for the detection of Cu(2+) ions.

    PubMed

    Li, Zhongping; Zhang, Yuwei; Xia, Hong; Mu, Ying; Liu, Xiaoming

    2016-05-01

    A hydrogen bond assisted azine-linked covalent organic framework, COF-JLU3, was synthesized under solvothermal conditions. Combining excellent crystallinity, porosity, stability and luminescence, it can be the first COF as a fluorescent sensor for toxic metal ions, exhibiting high sensitivity and selectivity to Cu(2+). PMID:27114234

  11. Structure-Triggered High Quantum Yield Luminescence and Switchable Dielectric Properties in Manganese(II) Based Hybrid Compounds.

    PubMed

    Wang, Zhong-Xia; Li, Peng-Fei; Liao, Wei-Qiang; Tang, Yuanyuan; Ye, Heng-Yun; Zhang, Yi

    2016-04-01

    Two new manganese(II) based organic-inorganic hybrid compounds, C11 H21 Cl3 MnN2 (1) and C11 H22 Cl4 MnN2 (2), with prominent photoluminescence and dielectric properties were synthesized by solvent modulation. Compound 1 with novel trigonal bipyramidal geometry exhibits bright red luminescence with a lifetime of 2.47 ms and high quantum yield of 35.8 %. Compound 2 with tetrahedral geometry displays intense long-lived (1.54 ms) green light emission with higher quantum yield of 92.3 %, accompanied by reversible solid-state phase transition at 170 K and a distinct switchable dielectric property. The better performance of 2 results from the structure, including a discrete organic cation moiety and inorganic metal anion framework, which gives the cations large freedom of motion. PMID:26864910

  12. Absorption and Luminescence Studies of Some Highly Fluorescent Derivatives of Vitamin B1; Solvent and pH Effects

    NASA Astrophysics Data System (ADS)

    Marciniak, B.; Koput, J.; Kozubek, H.

    1990-08-01

    The influence of solvent on the UV-visible absorption and luminescence spectra of some highly fluorescent vitamin B1 derivatives, the products of the reaction of N-methylated vitamin B1 with cytidine (I), adenosine (II) and 2-amino-4-methylpyridine (III) is studied. Spectroscopic manifestations of protonation of I and II are also investigated using a semiempirical INDO/S CI method. Singlet and triplet energy levels of the free ion and several protonated species are calculated, and transition energies and oscillator strengths are compared with the experimental spectra. Calculated charge densities on heteroatoms in the ground and excited singlet and triplet states are correlated with changes of the experimental pKa values with excitation. The results for I and II are compared with those for the trimethylated pyrichrominium ion (III) previously studied

  13. Dynamics of polydots: Soft luminescent polymeric nanoparticles

    DOE PAGESBeta

    Maskey, Sabina; Osti, Naresh C.; Grest, Gary S.; Perahia, Dvora

    2016-03-04

    The conformation and dynamics of luminescent polymers collapsed into nanoparticles or polydots were studied using fully atomistic molecular dynamics (MD) simulations, providing a first insight into their internal dynamics. Controlling the conformation and dynamics of confined polymers is essential for realization of the full potential of polydots in nanomedicine and biotechnology. Specifically, the shape and internal dynamics of polydots that consist of highly rigid dialkyl p-phenylene ethynylene (PPE) are probed as a function of temperature. At room temperature, the polydots are spherical without any correlations between the aromatic rings on the PPE backbone. With increasing temperature, they expand and becomemore » slightly aspherical; however, the polymers remain confined. The coherent dynamic structure factor reveals that the internal motion of the polymer backbone is arrested, and the side chains dominate the internal dynamics of the polydots. Lastly, these new soft nanoparticles retain their overall shape and dynamics over an extended temperature range, and their conformation is tunable via their degree of expansion.« less

  14. Low-Cost Manufacturing of High- Temperature Polymer Composites

    NASA Technical Reports Server (NTRS)

    Sutter, James K.

    1998-01-01

    Major goals of NASA and the Integrated High Performance Turbine Engine Technology (IHPTET) initiative include improvements in the affordability of propulsion systems, significant increases in the thrust/weight ratio, and increases in the temperature capability of components of gas turbine engines. Members of NASA Lewis Research Center's HITEMP project worked cooperatively with Allison Advanced Development Corporation to develop a manufacturing method to produce low-cost components for gas turbine engines. Affordability for these polymer composites is defined by the savings in acquisition and life-cycle costs associated with engine weight reduction. To lower engine component costs, the Lewis/Allison team focused on chopped graphite fiber/polyimide resin composites. The high-temperature polyimide resin chosen, PMR-II-50, was developed at NASA Lewis.

  15. High index contrast polymer waveguide platform for integrated biophotonics.

    PubMed

    Halldorsson, Jennifer; Arnfinnsdottir, Nina B; Jonsdottir, Asta B; Agnarsson, Björn; Leosson, Kristjan

    2010-07-19

    We present detailed characterization of a unique high-index-contrast integrated optical polymer waveguide platform where the index of the cladding material is closely matched to that of water. Single-mode waveguides designed to operate across a large part of the visible spectrum have been fabricated and waveguide properties, including mode size, bend loss and evanescent coupling have been modeled using effective-index approximation, finite-element and finite-difference time domain methods. Integrated components such as directional couplers for wavelength splitting and ring resonators for refractive-index or temperature sensing have been modeled, fabricated and characterized. The waveguide platform described here is applicable to a wide range of biophotonic applications relying on evanescent-wave sensing or excitation, offering a high level of integration and functionality. The technology is biocompatible and suitable for wafer-level mass production. PMID:20721007

  16. High-sensitivity and wide-directivity ultrasound detection using high Q polymer microring resonators

    PubMed Central

    Ling, Tao; Chen, Sung-Liang; Guo, L. Jay

    2011-01-01

    Small size ultrahigh Q polymer microrings working at near visible wavelength have been experimentally demonstrated as ultralow noise ultrasound detectors with wide directivity at high frequencies (>20 MHz). By combining a resist reflow and a low bias continuous etching and passivation process in mold fabrication, imprinted polymer microrings with drastically improved sidewall smoothness were obtained. An ultralow noise-equivalent pressure of 21.4 Pa over 1–75 MHz range has been achieved using a fabricated detector of 60 μm diameter. The device’s wide acceptance angle with high sensitivity considerably benefits ultrasound-related imaging. PMID:21673832

  17. Two double and triple interpenetrated Cd(II) and Zn(II) coordination polymers based on mixed O- and N-donor ligands: Syntheses, crystal structures and luminescent properties

    NASA Astrophysics Data System (ADS)

    Zhang, Li; Li, Xiaohui; Zhang, Yan

    2016-01-01

    Two interpenetrated 3D coordination polymers, namely [Cd2(tdc)2(bpp) (DMA)]n (1) and [Zn2(tdc)2(bib)2]n·2n(DMA) (2) (H2tdc = 2,5-thiophenedicarboxylic acid, bpp = 1,3-di(4-pyridyl)propane, bib = 1, 4-bis(imidazolyl)butane, DMA = N,N-dimethylacetamide), have been solvothermally synthesized by the self-assembly of flexible N-donor and dicarboxylate ligands. Single crystal X-ray diffraction analyses revealed that compound 1 features a 2-fold interpenetrated 3D framework based on dinuclear [Cd2(COO)3] subunits and can be simplified into a 6-connected pcu topology, and compound 2 features a 3-fold interpenetrated 3D framework with 4-connected dia topology. Moreover, the thermal stabilities and luminescent properties of these two compounds were also investigated.

  18. Deformation and fracture toughness in high-performance polymers

    SciTech Connect

    Pater, R.H.; Soucek, M.D.; Jang, B.Z.

    1993-12-31

    A systematic study was made of 10 principal high-performance thermoplastics and two semiinterpenetrating polymer networks (semi-IPNs). The fundamental tendency to undergo localized crazing or shear banding, as opposed to a more diffuse homogeneous shear-yielding deformation, was evaluated. Amorphous thermoplastics exhibited crazing as the primary mode of deformation. In contrast, semi-crystalline materials displayed both crazing and shear banding. Increasing the crystallinity increased diffuse shear yielding at the expense of craze growth. Another effect was an enlargement of the deformation zone. Some ordered polymers showed only diffuse shear yielding, whereas others displayed a combination of weak crazes and diffuse shear yielding. For a semi-IPN, increasing the degree of cross-linking decreased crazing, deformation zone size, and fracture toughness of an amorphous thermoplastic. Thus, crystallinity acts like cross-linking in reducing crazing, but, exerts the opposite effect on changing the size of the deformation zone. These results suggest that the reduction in fracture toughness by crystallinity is mainly due to decreased crazing, whereas reduction by cross-linking arises from both decreased crazing and diminished deformation zone. 43 refs., 42 figs., 1 tab.

  19. Nematic polymer liquid-crystal wave plate for high-power lasers at 1054 nm

    SciTech Connect

    Kreuzer, F. ); Korenic, E.M.; Jacobs, S.D.; Houghton, J.K.; Schmid, A. )

    1994-04-01

    A nematic polymer liquid crystal is used to construct wave plates for use at 1054 nm. Three methods of wave-plate construction are discussed: double substrate with fiber spacers in homogeneous distribution, double substrate with fiber spacers in annular distribution, and single substrate. The polymer liquid crystal shows high laser-damage resistance, making it particularly useful for high-peak-power laser applications. Alignment techniques and measurement of birefringence for the highly viscous polymer are described.

  20. Syntheses, crystal structures and luminescent properties of two new 1D d {sup 1} coordination polymers constructed from 2,2'-bibenzimidazole and 1,4-benzenedicarboxylate

    SciTech Connect

    Wen Lili; Li Yizhi; Dang Dongbin; Tian Zhengfang; Ni Zhaoping; Meng Qingjin . E-mail: mengqj@nju.edu.cn

    2005-11-15

    Two novel interesting d {sup 1} metal coordination polymers, [Zn(H{sub 2}bibzim)(BDC)] {sub n} (1) and [Cd(H{sub 2}bibzim)(BDC)] {sub n} (2) [H{sub 2}bibzim=2,2'-bibenzimidazole, BDC=1,4-benzenedicarboxylate] have been synthesized under solvothermal conditions and structurally characterized. Both 1 and 2 are constructed from infinite neutral zigzag-like one-dimensional (1D) chains. The {pi}-{pi} interactions and interchain hydrogen-bonding interactions further extend the 1D arrangement to generate a 3D supramolecular architecture for 1 and 2. Both complexes have high thermal stability and display strong blue fluorescent emissions in the solid state upon photo-excitation at 365 nm at room temperature. They are the first two examples that 2,2'-bibenzimidazole has been introduced into the d {sup 1} coordination polymeric framework.

  1. Tunable high aspect ratio polymer nanostructures for cell interfaces

    NASA Astrophysics Data System (ADS)

    Beckwith, Kai Sandvold; Cooil, Simon P.; Wells, Justin W.; Sikorski, Pawel

    2015-04-01

    Nanoscale topographies and chemical patterns can be used as synthetic cell interfaces with a range of applications including the study and control of cellular processes. Herein, we describe the fabrication of high aspect ratio nanostructures using electron beam lithography in the epoxy-based polymer SU-8. We show how nanostructure geometry, position and fluorescence properties can be tuned, allowing flexible device design. Further, thiol-epoxide reactions were developed to give effective and specific modification of SU-8 surface chemistry. SU-8 nanostructures were made directly on glass cover slips, enabling the use of high resolution optical techniques such as live-cell confocal, total internal reflection and 3D structured illumination microscopy to investigate cell interactions with the nanostructures. Details of cell adherence and spreading, plasma membrane conformation and actin organization in response to high aspect ratio nanopillars and nanolines were investigated. The versatile structural and chemical properties combined with the high resolution cell imaging capabilities of this system are an important step towards the better understanding and control of cell interactions with nanomaterials.Nanoscale topographies and chemical patterns can be used as synthetic cell interfaces with a range of applications including the study and control of cellular processes. Herein, we describe the fabrication of high aspect ratio nanostructures using electron beam lithography in the epoxy-based polymer SU-8. We show how nanostructure geometry, position and fluorescence properties can be tuned, allowing flexible device design. Further, thiol-epoxide reactions were developed to give effective and specific modification of SU-8 surface chemistry. SU-8 nanostructures were made directly on glass cover slips, enabling the use of high resolution optical techniques such as live-cell confocal, total internal reflection and 3D structured illumination microscopy to investigate cell

  2. Pure zinc sulfide quantum dot as highly selective luminescent probe for determination of hazardous cyanide ion.

    PubMed

    Shamsipur, Mojtaba; Rajabi, Hamid Reza

    2014-03-01

    A rapid and simple fluorescence method is presented for selective and sensitive determination of hazardous cyanide ion in aqueous solution based on functionalized zinc sulfide (ZnS) quantum dot (QD) as luminescent prob. The ultra-small ZnS QDs were synthesized using a chemical co-precipitation method in the presence of 2-mercaptoethanol (ME) as an efficient capping agent. The prepared pure ZnS QDs was applied as an optical sensor for determination of cyanide ions in aqueous solutions. ZnS nanoparticles have exhibited a strong fluorescent emission at about 424 nm. The fluorescence intensity of QDs is linearly proportional to the cyanide ion concentration in the range 2.44×10(-6) to 2.59×10(-5)M with a detection limit of 1.70×10(-7)M at pH11. The designed fluorescent sensor possesses remarkable selectivity for cyanide ion over other anions such as Cl(-), Br(-), F(-), I(-), IO3(-), ClO4(-), BrO3(-), CO3(2-), NO2(-), NO3(-), SO4(2-), S2O4(2-), C2O4(2-), SCN(-), N3(-), citrate and tartarate with negligible influences on the cyanide detection by fluorescence spectroscopy. PMID:24433896

  3. Dating loess with high temperature IRSL signals from polymineral fine grains: luminescence characteristics and comparison with conventional techniques

    NASA Astrophysics Data System (ADS)

    Thiel, C.; Buylaert, J.-P.; Murray, A. S.; Tsukamoto, S.; Jain, M.; Frechen, M.

    2009-04-01

    % of the given dose). This high temperature signal is also bleachable by daylight, as confirmed by the values of De observed in young samples and by performing controlled laboratory bleaching experiments. The enhanced post-IR IR dating protocol was applied to loess samples from Austria and Japan and compared with standard IRSL at 50°C and quartz OSL measurements. First results suggest that there is good agreement for the younger samples of Weichselian age but that the ages begin to deviate for the older samples. Final results, including a comparison with independent age control provided by known age tephra layers for the Japan samples (Watanuki et al., 2005), will be presented. Buylaert, J. P., Murray, A. S., Thomsen, K. J., Jain, M., accepted. Testing the potential of an elevated temperature IRSL signal from K-feldspar. Radiation Measurements, Special Issue, LED08. Murray, A. S., Buylaert, J. P., Thomsen, K. J., Jain, M., accepted. The Effect of Preheating on the IRSL Signal from Feldspar. Radiation Measurements, Special Issue, LED08. Thomsen, K. J., Murray, A. S., Jain, M., Bøtter-Jensen, L., 2008. Laboratory fading rates of various luminescence signals from feldspar-rich sediment extracts. Radiation Measurements, 43, 1474-1486. Watanuki, T., Murray, A. S., Tsukamoto, S., 2005. Quartz and polymineral luminescence dating of Japanese loess over the last 0.6 Ma: Comparison with an independent chronology. Earth and Planetary Science Letters, 240, 774-789.

  4. Rheological investigation of highly filled polymers: Effect of molecular weight

    NASA Astrophysics Data System (ADS)

    Hnatkova, Eva; Hausnerova, Berenika; Hales, Andrew; Jiranek, Lukas; Vera, Juan Miguel Alcon

    2015-04-01

    The paper deals with rheological properties of highly filled polymers used in powder injection molding. Within the experimental framework seven PIM feedstocks based on superalloy Inconel 718 powder were prepared. Each feedstock contains the fixed amount of powder loading and the same composition of binder system consisting of three components: polyethylene glycol (PEG) differing in molecular weight, poly (methyl methacrylate) (PMMA) and stearic acid (SA). The aim is to investigate the influence of PEG's molecular weight on the flow properties of feedstocks. Non-Newtonian indices, representing the shear rate sensitivity of the feedstocks, are obtained from a polynomial fit, and found to vary within measured shear rates range from 0.2 to 0.8. Temperature effect is considered via activation energies, showing decreasing trend with increasing of molecular weight of PEG (except of feedstock containing 1,500 g.mol-1 PEG).

  5. Luminescent zinc and cadmium complexes incorporating 1,3,5-benzenetricarboxylate and a protonated kinked organodiimine: From a hydrogen-bonded layer motif to thermally robust two-dimensional coordination polymers

    SciTech Connect

    Braverman, Maxwell A.; Supkowski, Ronald M.; LaDuca, Robert L.

    2007-06-15

    Hydrothermal treatment of zinc chloride, 1,3,5-benzenetricarboxylic acid (H{sub 3}BTC), and 4,4'-dipyridylamine (dpa) afforded two different complexes depending on reaction conditions, which were characterized by single-crystal X-ray diffraction, infrared spectroscopy, and elemental analysis. Under acidic conditions, a discrete neutral molecular species with formulation [Zn(HBTC){sub 2}(Hdpa){sub 2}] (1) was isolated, which aggregates into two-dimensional hydrogen-bonded layers. Under more basic conditions, the two-dimensional layered coordination polymer [Zn(BTC)(Hdpa)] (2) is obtained, which manifests covalent linkage of [Zn(BTC)(Hdpa)] serpentine chain motifs into 3-connected undulating 4.8{sup 2} topology 2-D layers. Both 1 and 2 possess tetrahedral coordination at Zn. Use of cadmium nitrate in the synthesis resulted in [Cd(BTC)(H{sub 2}O)(Hdpa)] (3), which displays a similar layer topology as 2 but with significant adjustments imparted by octahedral coordination at Cd. In all cases, supramolecular hydrogen bonding promoted by Hdpa ligands provide an important assistive structure-directing role. All materials display blue luminescence upon excitation with ultraviolet light, ascribed to intraligand transitions. Crystallographic data: 1: monoclinic, C2/c, a=25.389(6) A, b=9.811(2) A, c=17.309(4) A, and {beta}=128.957(3){sup o}, 2: monoclinic, P2{sub 1}/c, a=13.212(17)c, b=17.15(2) A, c=7.506(10) A, and {beta}=93.71(2){sup o}, and 3: monoclinic, C2/c, a=14.241(6) A, b=15.218(6) A, c=17.976(7) A, and {beta}=109.330(6){sup o}. - Graphical abstract: Hydrothermal synthesis has afforded a family of luminescent complexes based on divalent d {sup 10} cations with 1,3,5-benzenetricarboxylate (BTC) and 4,4'-dipyridylamine (dpa) ligands. [Zn(HBTC){sub 2}(Hdpa){sub 2}] (1) is a discrete neutral molecular species. [Zn(BTC)(Hdpa)] (2, pictured) and [Cd(BTC)(H{sub 2}O)(Hdpa)] (3) are 2-D coordination polymers with different morphologies depending on coordination geometry at the

  6. Monolithic polymer microlens arrays with high numerical aperture and high packing density.

    PubMed

    Jung, Hyukjin; Jeong, Ki-Hun

    2015-02-01

    This work reports a novel method for monolithic fabrication of high numerical aperture polymer microlens arrays (high-NA MLAs) with high packing density (PD) at wafer level. The close-packed high-NA MLAs were fabricated by incorporating conformal deposition of ultrathin fluorocarbon nanofilm and melting the cylindrical polymer islands. The NA and PD of hemispherical MLAs with a hexagonal arrangement increase up to 0.6 and 89%, respectively. The increase of NA enhances the lens transmission securing the beam width down to 1.1 μm. The close-packed high-NA MLAs enable high photon collection efficiency with signal-to-noise ratio greater than 50:1. PMID:25612820

  7. Interpenetrating polymer network approach to tougher and more microcracking resistant high temperature polymers. I - LaRC-RP40

    NASA Technical Reports Server (NTRS)

    Pater, Ruth H.; Morgan, Cassandra D.

    1988-01-01

    Interpenetrating polymer networks in the form of the LaRC-RP40 resin, prepared by the in situ polymerization of a thermosetting imide prepolymer and thermoplastic monomer reactants, are presently used to obtain toughness and microcracking resistance in a high-temperature polymer. Attention is presently given to the processing, physical, and mechanical properties, as well as the thermooxidative stability, of both the neat resin and the resin as a graphite fiber-reinforced matrix. Microcracking after thermal cycling was also tested. LaRC-RP40 exhibits significant resin fracture toughness improvements over the PMR-15 high-temperature matrix resin.

  8. Utilization of star-shaped polymer architecture in the creation of high-density polymer brush coatings for the prevention of platelet and bacteria adhesion

    PubMed Central

    Totani, Masayasu; Terada, Kayo; Terashima, Takaya; Kim, Ill Yong; Ohtsuki, Chikara; Xi, Chuanwu; Tanihara, Masao

    2014-01-01

    We demonstrate utilization of star-shaped polymers as high-density polymer brush coatings and their effectiveness to inhibit the adhesion of platelets and bacteria. Star polymers consisting of poly(2-hydroxyethyl methacrylate) (PHEMA) and/or poly(methyl methacrylate) (PMMA), were synthesized using living radical polymerization with a ruthenium catalyst. The polymer coatings were prepared by simple drop casting of the polymer solution onto poly(ethylene terephthalate) (PET) surfaces and then dried. Among the star polymers prepared in this study, the PHEMA star polymer (star-PHEMA) and the PHEMA/PMMA (mol. ratio of 71/29) heteroarm star polymer (star-H71M29) coatings showed the highest percentage of inhibition against platelet adhesion (78–88% relative to noncoated PET surface) and Escherichia coli (94–97%). These coatings also showed anti-adhesion activity against platelets after incubation in Dulbecco's phosphate buffered saline or surfactant solution for 7 days. In addition, the PMMA component of the star polymers increased the scratch resistance of the coating. These results indicate that the star-polymer architecture provides high polymer chain density on PET surfaces to prevent adhesion of platelets and bacteria, as well as coating stability and physical durability to prevent exposure of bare PET surfaces. The star polymers provide a simple and effective approach to preparing anti-adhesion polymer coatings on biomedical materials against the adhesion of platelets and bacteria. PMID:25485105

  9. Utilization of star-shaped polymer architecture in the creation of high-density polymer brush coatings for the prevention of platelet and bacteria adhesion.

    PubMed

    Totani, Masayasu; Ando, Tsuyoshi; Terada, Kayo; Terashima, Takaya; Kim, Ill Yong; Ohtsuki, Chikara; Xi, Chuanwu; Kuroda, Kenichi; Tanihara, Masao

    2014-09-01

    We demonstrate utilization of star-shaped polymers as high-density polymer brush coatings and their effectiveness to inhibit the adhesion of platelets and bacteria. Star polymers consisting of poly(2-hydroxyethyl methacrylate) (PHEMA) and/or poly(methyl methacrylate) (PMMA), were synthesized using living radical polymerization with a ruthenium catalyst. The polymer coatings were prepared by simple drop casting of the polymer solution onto poly(ethylene terephthalate) (PET) surfaces and then dried. Among the star polymers prepared in this study, the PHEMA star polymer (star-PHEMA) and the PHEMA/PMMA (mol. ratio of 71/29) heteroarm star polymer (star-H71M29) coatings showed the highest percentage of inhibition against platelet adhesion (78-88% relative to noncoated PET surface) and Escherichia coli (94-97%). These coatings also showed anti-adhesion activity against platelets after incubation in Dulbecco's phosphate buffered saline or surfactant solution for 7 days. In addition, the PMMA component of the star polymers increased the scratch resistance of the coating. These results indicate that the star-polymer architecture provides high polymer chain density on PET surfaces to prevent adhesion of platelets and bacteria, as well as coating stability and physical durability to prevent exposure of bare PET surfaces. The star polymers provide a simple and effective approach to preparing anti-adhesion polymer coatings on biomedical materials against the adhesion of platelets and bacteria. PMID:25485105

  10. Fluoro-Substituted n-Type Conjugated Polymers for Additive-Free All-Polymer Bulk Heterojunction Solar Cells with High Power Conversion Efficiency of 6.71.

    PubMed

    Jung, Jae Woong; Jo, Jea Woong; Chueh, Chu-Chen; Liu, Feng; Jo, Won Ho; Russell, Thomas P; Jen, Alex K-Y

    2015-06-01

    Fluorinated n-type conjugated polymers are used as efficient electron acceptor to demonstrate high-performance all-polymer solar cells. The exciton generation, dissociation, and charge-transporting properties of blend films are improved by using these fluorinated n-type polymers to result in enhanced photocurrent and suppressed charge recombination. PMID:25900070

  11. Polymer Acceptor Based on Double B←N Bridged Bipyridine (BNBP) Unit for High-Efficiency All-Polymer Solar Cells.

    PubMed

    Long, Xiaojing; Ding, Zicheng; Dou, Chuandong; Zhang, Jidong; Liu, Jun; Wang, Lixiang

    2016-08-01

    A novel polymer acceptor based on the double B←N bridged bipyridine building block is reported. All-polymer solar cells based on the new polymer acceptor show a power conversion efficiency of as high as 6.26% at a photon energy loss of only 0.51 eV. PMID:27167123

  12. Stacked Polymer nanofiber array for high-performance supercapacitors

    NASA Astrophysics Data System (ADS)

    Wang, Shiren; Qiu, Jenny

    2015-03-01

    The vertically aligned polyaniline (PANI) nanowires arrays and monolayer graphene sheets were layer-by-layered deposited to specific substrate for tailored structures. Driven by external voltage, aniline molecules and graphene oxide were alternatively assembled for hierarchical porous three-dimensional nanostructures while graphene oxide was in-situ reduced to graphene during the assembly process. As-produced stacked arrays were used as the electrodes of an ultra-capacitor, and an unusual electrochemical behavior was discovered. The capacitance increases as the stack of nanowire arrays increases, resulting in high energy density and high power density at same time. Further analysis found that the distinctive electrochemical behavior originates from the electrode/electrolyte interactions and the dependence on the diffusion and charge transferring process. The specific energy density was as high as 137 Wh/Kg while power density is in excess of 2000 W/Kg. This work pointed a simple pathway to tailor polymer structure and electrochemistry for robust design of high-performance ultra-capacitor at a limited lateral size. National Science Foundation.

  13. Synthesis, structure, and luminescence property of a series of Ag-Ln coordination polymers with the N-heterocyclic carboxylato ligand

    NASA Astrophysics Data System (ADS)

    Jin, Jing; Chen, Chong; Gao, Yan; Zhao, Ran; Wang, Xiuyan; Lü, Chunxin; Chi, Yuxian; Niu, Shuyun

    2016-03-01

    Six Ln-Ag coordination polymers {[LnAg2(IN)4(H2O)5]·NO3·2H2O}n (Ln=Ho (1) and Tb (2), HIN=isonicotinic acid), {[PrAg2(IN)4(H2O)2]·NO3·H2O}n (3), [LnAg(pdc)2]n (Ln=Eu(4) and Pr (5), H2pdc=3,4-pyridine-dicarboxylic acid) and [NdAg(bidc)2(H2O)4]n (6) (H2bidc=benzimidazole-5,6-dicarboxylic acid) have been hydrothermally synthesized and characterized by single crystal X-ray diffraction, elemental analysis, IR, UV-vis-NIR absorption spectra, fluorescence spectra and thermogravimetric analysis. Structural analyses reveal that the six polymers exhibit 0D (polymer (1)), 1D (polymer (2)), 2D (polymers (3) and (5)) and 3D (polymers (4) and (6)) infinite structures, respectively. Polymers (1)-(6) exhibit the Ln(III) characteristic emission in the near-infrared (NIR) region or in the visible region. Especially, the NIR emission bands of polymers 1, 5 and 6 evidently present shift or splitting due to formation of the Ln-Ag coordination polymers. This can be attributed to the tune of inner levels in Ln-Ag system caused by the interact and influence between the 4d orbital of the Ag(I) ion and the 4f orbital of the Ln(III) ion, which can be confirmed by the UV-vis-NIR absorption spectra of the polymers. In addition, the distortion of coordination geometry as well as difference of the coordination number around the Ag(I) ion affect the structure framework.

  14. Main chain type benzoxaine polymers for high performance applications

    NASA Astrophysics Data System (ADS)

    Chernykh, Andrey

    A new polymer with benzoxazine group in the main chain has been synthesized through the Mannich condensation of a difunctional phenol, formaldehyde and a diamine. Obtained polymer has weight average molecular weight of approximately 10,000 Da and a moderately broad polydispersity index. The new polymer is used to manufacturer self-supporting film of thermosetting resins. Aiming to obtain higher molecular weight, click chemistry approach has been applied to synthesize linear benzoxazine polymers. Three types of polymers have been prepared from dipropargyl- and novel diazide-functionalized benzoxazine monomers, showing a tremendous flexibility for applying click reaction to obtain various polymer architectures. The weight average molecular weight is estimated to be in the range from 50,000 to 100,000 Da which is significantly higher than the benzoxazine polymers which have been chain extended via Mannich reaction. Further developing approach of polycondensation of the monomers containing ozaxine rings, the oxidative coupling approach has been utilized in order to couple benzoxazines with terminal acetylene groups. A model benzoxazine compound containing diacetylene linkage exhibits unexpectedly low exothermic peak with the onset around 140°C, which is significantly lower than the temperature of conventional benzoxazine polymerization. The initial model studies have been made in order to understand this phenomenon and preliminary explanation is given. Extending this pathway to the difunctional propargyl- and ethynyl-functionalized benzoxazine monomers, a series of novel benzoxazine polymers containing diacetylene groups in the main chain have been synthesized. The weight average molecular weight of the polymers is achieved to be up to 50,000 Da. The effect of diacetylene moiety on the benzoxazine crosslinking behavior is even more pronounced for the obtained linear polymers showing exothermic peak with the onset at around 125°C and its maximum at 185°C. Upon

  15. Sonochemical synthesis of highly luminescent Ln2O3:Eu3+ (Y, La, Gd) nanocrystals

    DOE PAGESBeta

    Alammar, Tarek; Cybinska, Joanna; Campbell, Paul S.; Mudring, Anja -Verena

    2015-05-12

    In this study, sonication of Ln(CH3COO)3·H2O, Eu(CH3COO)3·H2O and NaOH dissolved in the ionic liquid-butyl-3-methylimidazolium bis(trifluoromethane)sulfonylamide lead to Ln(OH)3:Eu (Ln: Gd, La, Y) nanoparticles. Subsequent calcination at 800 °C for 3 h allowed to obtain Ln2O3:Eu nanopowders. Gd2O3 and Y2O3 were obtained in the C-type lanthanide sequioxide structure, whereas La2O3 crystallized in the A-type. Structure, morphology, and luminescent properties of the nano-oxides were investigated by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), dispersive X-ray (EDX), and photoluminescence (PL). SEM studies revealed that the synthesized Gd2O3:Eu, La2O3:Eu, and Y2O3:Eu formed nano-spindle, -sheets, and -rods in shape, respectively. The nanoscale materials showmore » very efficient red emission due to the intraconfigurational f–f transitions of Eu3+. The quantum yields for Ln2O3:Eu (5%) were determined to be 4.2% for Ln=Gd, 13.8% for Ln=Y and 5.2% for Ln=La. The asymmetric ratio I02/I01 of Eu3+ varies from 5.3 for Gd2O3, to 5.6 for Y2O3 to 6.5 for La2O3, which increased the color chromaticity.« less

  16. Highly Efficient and Excitation Tunable Two-Photon Luminescence Platform For Targeted Multi-Color MDRB Imaging Using Graphene Oxide

    PubMed Central

    Pramanik, Avijit; Fan, Zhen; Chavva, Suhash Reddy; Sinha, Sudarson Sekhar; Ray, Paresh Chandra

    2014-01-01

    Multiple drug-resistance bacteria (MDRB) infection is one of the top three threats to human health according to the World Health Organization (WHO). Due to the large penetration depth and reduced photodamage, two-photon imaging is an highly promising technique for clinical MDRB diagnostics. Since most commercially available water-soluble organic dyes have low two-photon absorption cross-section and rapid photobleaching tendency, their applications in two-photon imaging is highly limited. Driven by the need, in this article we report extremely high two-photon absorption from aptamer conjugated graphene oxide (σ2PA = 50800 GM) which can be used for highly efficient two-photon fluorescent probe for MDRB imaging. Reported experimental data show that two-photon photoluminescence imaging color, as well as luminescence peak position can be tuned from deep blue to red, just by varying the excitation wavelength without changing its chemical composition and size. We have demonstrated that graphene oxide (GO) based two-photon fluorescence probe is capable of imaging of multiple antibiotics resistance MRSA in the first and second biological transparency windows using 760–1120 nm wavelength range. PMID:25125143

  17. Highly Efficient and Excitation Tunable Two-Photon Luminescence Platform For Targeted Multi-Color MDRB Imaging Using Graphene Oxide

    NASA Astrophysics Data System (ADS)

    Pramanik, Avijit; Fan, Zhen; Chavva, Suhash Reddy; Sinha, Sudarson Sekhar; Ray, Paresh Chandra

    2014-08-01

    Multiple drug-resistance bacteria (MDRB) infection is one of the top three threats to human health according to the World Health Organization (WHO). Due to the large penetration depth and reduced photodamage, two-photon imaging is an highly promising technique for clinical MDRB diagnostics. Since most commercially available water-soluble organic dyes have low two-photon absorption cross-section and rapid photobleaching tendency, their applications in two-photon imaging is highly limited. Driven by the need, in this article we report extremely high two-photon absorption from aptamer conjugated graphene oxide (σ2PA = 50800 GM) which can be used for highly efficient two-photon fluorescent probe for MDRB imaging. Reported experimental data show that two-photon photoluminescence imaging color, as well as luminescence peak position can be tuned from deep blue to red, just by varying the excitation wavelength without changing its chemical composition and size. We have demonstrated that graphene oxide (GO) based two-photon fluorescence probe is capable of imaging of multiple antibiotics resistance MRSA in the first and second biological transparency windows using 760-1120 nm wavelength range.

  18. Thermodynamics of water sorption in high performance glassy thermoplastic polymers

    PubMed Central

    Scherillo, Giuseppe; Petretta, Mauro; Galizia, Michele; La Manna, Pietro; Musto, Pellegrino; Mensitieri, Giuseppe

    2014-01-01

    Sorption thermodynamics of water in two glassy polymers, polyetherimide (PEI) and polyetheretherketone (PEEK), is investigated by coupling gravimetry and on line FTIR spectroscopy in order to gather information on the total amount of sorbed water as well as on the different species of water molecules absorbed within the polymers, addressing the issue of cross- and self-interactions occurring in the polymer/water systems. Water sorption isotherms have been determined at temperatures ranging from 30 to 70°C while FTIR spectroscopy has been performed only at 30°C. The experimental analysis provided information on the groups present on the polymer backbones involved in hydrogen bonding interactions with absorbed water molecules. Moreover, it also supplied qualitative indications about the different “populations” of water molecules present within the PEEK and a quantitative assessment of these “populations” in the case of PEI. The results of the experimental analysis have been interpreted using an equation of state theory based on a compressible lattice fluid model for the Gibbs energy of the polymer-water mixture, developed by extending to the case of out of equilibrium glassy polymers a previous model intended for equilibrium rubbery polymers. The model accounts for the non-equilibrium nature of glassy polymers as well as for mean field and for hydrogen bonding interactions, providing a satisfactory quantitative interpretation of the experimental data. PMID:24860802

  19. High-performance polymer/layered silicate nanocomposites

    NASA Astrophysics Data System (ADS)

    Heidecker, Matthew J.

    High-performance layered-silicate nanocomposites of Polycarbonate (PC), poly(ethylene terephthalate) (PET), and their blends were produced via conventional melt-blending techniques. The focus of this thesis was on the fundamentals of dispersion, control of thermal stability, maintenance of melt-blending processing conditions, and on optimization of the composites' mechanical properties via the design of controlled and thermodynamically favorable nano-filler dispersions within the polymer matrices. PET and PC require high temperatures for melt-processing, rendering impractical the use of conventional/commercial organically-modified layered-silicates, since the thermal degradation temperatures of their ammonium surfactants lies below the typical processing temperatures. Thus, different surfactant chemistries must be employed in order to develop melt-processable nanocomposites, also accounting for polymer matrix degradation due to water (PET) or amine compounds (PC). Novel high thermal-stability surfactants were developed and employed in montmorillonite nanocomposites of PET, PC, and PC/PET blends, and were compared to the respective nanocomposites based on conventional quaternary-ammonium modified montmorillonites. Favorable dispersion was achieved in all cases, however, the overall material behavior -- i.e., the combination of crystallization, mechanical properties, and thermal degradation -- was better for the nanocomposites based on the thermally-stable surfactant fillers. Studies were also done to trace, and ultimately limit, the matrix degradation of Polycarbonate/montmorillonite nanocomposites, through varying the montmorillonite surfactant chemistry, processing conditions, and processing additives. Molecular weight degradation was, maybe surprisingly, better controlled in the conventional quaternary ammonium based nanocomposites -- even though the thermal stability of the organically modified montmorillonites was in most cases the lowest. Dependence of the

  20. Polymer nanocomposites for high-temperature composite repair

    SciTech Connect

    Sheng, Xia

    2008-01-01

    A novel repair agent for resin-injection repair of advanced high temperature composites was developed and characterized. The repair agent was based on bisphenol E cyanate ester (BECy) and reinforced with alumina nanoparticles. To ensure good dispersion and compatibility with the BECy matrix in nanocomposites, the alumina nanoparticles were functionalized with silanes. The BECy nanocomposites, containing bare and functionalized alumina nanoparticles, were prepared and evaluated for their thermal, mechanical, rheological, and viscoelastic properties. The monomer of BECy has an extremely low viscosity at ambient temperature, which is good for processability. The cured BECy polymer is a highly cross-linked network with excellent thermal mechanical properties, with a high glass transition temperature (Tg) of 270 C and decomposition temperature above 350 C. The incorporation of alumina nanoparticles enhances the mechanical and rheological properties of the BECy nanocomposites. Additionally, the alumina nanoparticles are shown to catalyze the cure of BECy. Characterization of the nanocomposites included dynamic mechanical analysis, differential scanning calorimetry, thermogravimetric analysis, rheological and rheokinetic evaluation, and transmission electron microscopy. The experimental results show that the BECy nanocomposite is a good candidate as repair agent for resin-injection repair applications.

  1. Polymer nanocomposites for high-temperature composite repair

    NASA Astrophysics Data System (ADS)

    Sheng, Xia

    A novel repair agent for resin-injection repair of advanced high temperature composites was developed and characterized. The repair agent was based on bisphenol E cyanate ester (BECy) and reinforced with alumina nanoparticles. To ensure good dispersion and compatibility with the BECy matrix in nanocomposites, the alumina nanoparticles were functionalized with silanes. The BECy nanocomposites, containing bare and functionalized alumina nanoparticles, were prepared and evaluated for their thermal, mechanical, rheological, and viscoelastic properties. The monomer of BECy has an extremely low viscosity at ambient temperature, which is good for processability. The cured BECy polymer is a highly cross-linked network with excellent thermal mechanical properties, with a high glass transition temperature (Tg) of 270 °C and decomposition temperature above 350 °C. The incorporation of alumina nanoparticles enhances the mechanical and rheological properties of the BECy nanocomposites. Additionally, the alumina nanoparticles are shown to catalyze the cure of BECy. Characterization of the nanocomposites included dynamic mechanical analysis, differential scanning calorimetry, thermogravimetric analysis, rheological and rheokinetic evaluation, and transmission electron microscopy. The experimental results show that the BECy nanocomposite is a good candidate as repair agent for resin-injection repair applications.

  2. General strategy for self-assembly of highly oriented nanocrystalline semiconducting polymers with high mobility.

    PubMed

    Luo, Chan; Kyaw, Aung Ko Ko; Perez, Louis A; Patel, Shrayesh; Wang, Ming; Grimm, Bruno; Bazan, Guillermo C; Kramer, Edward J; Heeger, Alan J

    2014-05-14

    Solution processable semiconducting polymers with excellent film forming capacity and mechanical flexibility are considered among the most progressive alternatives to conventional inorganic semiconductors. However, the random packing of polymer chains and the disorder of the polymer matrix typically result in low charge transport mobilities (10(-5)-10(-2) cm(2) V(-1) s(-1)). These low mobilities compromise their performance and development. Here, we present a strategy, by utilizing capillary action, to mediate polymer chain self-assembly and unidirectional alignment on nanogrooved substrates. We designed a sandwich tunnel system separated by functionalized glass spacers to induce capillary action for controlling the polymer nanostructure, crystallinity, and charge transport. Using capillary action, we demonstrate saturation mobilities with average values of 21.3 and 18.5 cm(2) V(-1 )s(-1) on two different semiconducting polymers at a transistor channel length of 80 μm. These values are limited by the source-drain contact resistance, Rc. Using a longer channel length of 140 μm where the contact resistance is less important, we measured μh = 36.3 cm(2) v(-1) s(-1). Extrapolating to infinite channel length where Rc is unimportant, the intrinsic mobility for poly[4-(4,4-dihexadecyl-4H-cyclopenta[1,2-b:5,4-b']dithiophen-2-yl)-alt-[1,2,5]thiadiazolo[3,4-c]pyridine] (Mn = 140 kDa) at this degree of chain alignment and structural order is μh ≈ 47 cm(2 )v(-1) s(-1). Our results create a promising pathway toward high performance, solution processable, and low-cost organic electronics. PMID:24712578

  3. Aggregation and morphology control enables multiple cases of high-efficiency polymer solar cells

    PubMed Central

    Liu, Yuhang; Zhao, Jingbo; Li, Zhengke; Mu, Cheng; Hu, Huawei; Jiang, Kui; Lin, Haoran; Ade, Harald; Yan, He

    2014-01-01

    Although the field of polymer solar cell has seen much progress in device performance in the past few years, several limitations are holding back its further development. For instance, current high-efficiency (>9.0%) cells are restricted to material combinations that are based on limited donor polymers and only one specific fullerene acceptor. Here we report the achievement of high-performance (efficiencies up to 10.8%, fill factors up to 77%) thick-film polymer solar cells for multiple polymer:fullerene combinations via the formation of a near-ideal polymer:fullerene morphology that contains highly crystalline yet reasonably small polymer domains. This morphology is controlled by the temperature-dependent aggregation behaviour of the donor polymers and is insensitive to the choice of fullerenes. The uncovered aggregation and design rules yield three high-efficiency (>10%) donor polymers and will allow further synthetic advances and matching of both the polymer and fullerene materials, potentially leading to significantly improved performance and increased design flexibility. PMID:25382026

  4. Aggregation and morphology control enables multiple cases of high-efficiency polymer solar cells.

    PubMed

    Liu, Yuhang; Zhao, Jingbo; Li, Zhengke; Mu, Cheng; Ma, Wei; Hu, Huawei; Jiang, Kui; Lin, Haoran; Ade, Harald; Yan, He

    2014-01-01

    Although the field of polymer solar cell has seen much progress in device performance in the past few years, several limitations are holding back its further development. For instance, current high-efficiency (>9.0%) cells are restricted to material combinations that are based on limited donor polymers and only one specific fullerene acceptor. Here we report the achievement of high-performance (efficiencies up to 10.8%, fill factors up to 77%) thick-film polymer solar cells for multiple polymer:fullerene combinations via the formation of a near-ideal polymer:fullerene morphology that contains highly crystalline yet reasonably small polymer domains. This morphology is controlled by the temperature-dependent aggregation behaviour of the donor polymers and is insensitive to the choice of fullerenes. The uncovered aggregation and design rules yield three high-efficiency (>10%) donor polymers and will allow further synthetic advances and matching of both the polymer and fullerene materials, potentially leading to significantly improved performance and increased design flexibility. PMID:25382026

  5. MnBr₂/18-crown-6 coordination complexes showing high room temperature luminescence and quantum yield.

    PubMed

    Hausmann, David; Kuzmanoski, Ana; Feldmann, Claus

    2016-04-21

    The reaction of manganese(ii) bromide and the crown ether 18-crown-6 in the ionic liquid [(n-Bu)3MeN][N(Tf)2] under mild conditions (80-130 °C) resulted in the formation of three different coordination compounds: MnBr2(18-crown-6) (), Mn3Br6(18-crown-6)2 () and Mn3Br6(18-crown-6) (). In general, the local coordination and the crystal structure of all compounds are driven by the mismatch between the small radius of the Mn(2+) cation (83 pm) and the ring opening of 18-crown-6 as a chelating ligand (about 300 pm). This improper situation leads to different types of coordination and bonding. MnBr2(18-crown-6) represents a molecular compound with Mn(2+) coordinated by two bromine atoms and only five oxygen atoms of 18-crown-6. Mn3Br6(18-crown-6)2 falls into a [MnBr(18-crown-6)](+) cation - with Mn(2+) coordinated by six oxygen atoms and Br - and a [MnBr(18-crown-6)MnBr4](-) anion. In this anion, Mn(2+) is coordinated by five oxygen atoms of the crown ether as well as by two bromine atoms, one of them bridging to an isolated (MnBr4) tetrahedron. Mn3Br6(18-crown-6), finally, forms an infinite, non-charged [Mn2(18-crown-6)(MnBr6)] chain. Herein, 18-crown-6 is exocyclically coordinated by two Mn(2+) cations. All compounds show intense luminescence in the yellow to red spectral range and exhibit remarkable quantum yields of 70% (Mn3Br6(18-crown-6)) and 98% (Mn3Br6(18-crown-6)2). The excellent quantum yield of Mn3Br6(18-crown-6)2 and its differentiation from MnBr2(18-crown-6) and Mn3Br6(18-crown-6) can be directly correlated to the local coordination. PMID:26956783

  6. Mössbauer Investigation of Highly Dispersed Iron Particles in Crazed Porous Polymers

    NASA Astrophysics Data System (ADS)

    Trofimchuk, E. S.; Nikonorova, N. I.; Dedushenko, S. K.; Perfiliev, Y. D.

    2004-12-01

    Formation and stability of highly dispersed iron particles in crazed porous polymer matrices were studied. The iron polymer composites obtained were characterized by different morphologies and dimensions of iron particles. The phase content of the iron constituent in a composite studied by Mössbauer spectroscopy was shown to depend on the type of the iron salt and the method of introduction of the initial reagents into a polymer.

  7. A luminescent down-shifting and moth-eyed anti-reflective film for highly efficient photovoltaic devices

    NASA Astrophysics Data System (ADS)

    Ghymn, Yong H.; Jung, Kinam; Shin, Myunghun; Ko, Hyungduk

    2015-11-01

    Adhesive polydimethylsiloxane (PDMS) films were developed to increase the performance of photovoltaic devices. The films combined two separate features of moth-eye patterns to reduce the reflection of incident light at the film surface and luminescent down-shifting (LDS) CdZnS/ZnS-core/shell quantum dots (QDs) to convert ultraviolet (UV) radiation into visible light at 445 nm. The films were both flexible and self-adhesive, easily attachable to any surface of a solar cell module. By simply attaching the developed films on high-efficiency GaAs solar cells, the short circuit current density and power conversion efficiency of the solar cells increased to 33.8 mA cm-2 and 28.7%, by 1.1 mA cm-2 and 0.9 percentage points in absolute values, respectively. We showed that the enhancement of the GaAs solar cells was attributed to both the anti-reflection (AR) properties of the moth-eye patterns and the LDS of QDs using a scattering matrix method and external quantum efficiency measurements. The developed films are versatile in application for solar cells, and expected to aid in overcoming limits of material absorption and device structures.Adhesive polydimethylsiloxane (PDMS) films were developed to increase the performance of photovoltaic devices. The films combined two separate features of moth-eye patterns to reduce the reflection of incident light at the film surface and luminescent down-shifting (LDS) CdZnS/ZnS-core/shell quantum dots (QDs) to convert ultraviolet (UV) radiation into visible light at 445 nm. The films were both flexible and self-adhesive, easily attachable to any surface of a solar cell module. By simply attaching the developed films on high-efficiency GaAs solar cells, the short circuit current density and power conversion efficiency of the solar cells increased to 33.8 mA cm-2 and 28.7%, by 1.1 mA cm-2 and 0.9 percentage points in absolute values, respectively. We showed that the enhancement of the GaAs solar cells was attributed to both the anti

  8. Studies of radiation effects in three high polymers

    SciTech Connect

    Ries, H.R.M.

    1987-01-01

    Three high polymers, Mylar, Ultem, and Kapton, were irradiated to total doses of 1, 5, and 9.5 gigarad using 1-MeV electrons. The glass transition temperatures of the materials before and after irradiation were measured using an AC electrical dissipation factor technique. From these data, it was found that the electron radiation at these total doses results in net-chain scissioning in Mylar and net crosslinking in Ultem, while self-mending is predominant in Kapton. The dielectric constant was measured before and after irradiation, but no significant changes due to irradiation were observed. Electron paramagnetic resonance (EPR) was used to determine the total organic radical densities in the materials 0.5 hr after irradiation. Total organic radical densities of approximately qo/sup 18/ spins/g were recorded in all three materials. Additional post-irradiation EPR radical density measurements were made at later times to determine the radical decay rates. The radical decay rates were highly varied and did not conform to first-order or second-order decay kinetics, due to the simultaneous presence of several different radical species. Utilizing the EPR spectra, post-irradiation radical identifications were made for all three materials.

  9. High Glass Transition Temperature Renewable Polymers via Biginelli Multicomponent Polymerization.

    PubMed

    Boukis, Andreas C; Llevot, Audrey; Meier, Michael A R

    2016-04-01

    A novel and straightforward one-pot multicomponent polycondensation method was established in this work. The Biginelli reaction is a versatile multicomponent reaction of an aldehyde, a β-ketoester (acetoacetate) and urea, which can all be obtained from renewable resources, yielding diversely substituted 3,4-dihydropyrimidin-2(1H)-ones (DHMPs). In this study, renewable diacetoacetate monomers with different spacer chain lengths (C3, C6, C10, C20) were prepared via simple transesterification of renewable diols and commercial acetoacetates. The diacetoacetate monomers were then reacted with renewable dialdehydes, i.e., terephthalaldehyde and divanillin in a Biginelli type step-growth polymerization. The obtained DHMP polymers (polyDHMPs) displayed high molar masses, high glass transition temperatures (Tg) up to 203 °C and good thermal stability (Td5%) of 280 °C. The Tg of the polyDHMPs could be tuned by variation of the structure of the dialdehyde or the diacetoacetate component. PMID:26800511

  10. Ag-SiO2-Er2O3 Nanocomposites: Highly Effective Upconversion Luminescence at High Power Excitation and High Temperature

    PubMed Central

    Xu, Wen; Min, Xiaolei; Chen, Xu; Zhu, Yongsheng; Zhou, Pingwei; Cui, Shaobo; Xu, Sai; Tao, Li; Song, Hongwei

    2014-01-01

    Rare Earth (RE) activated upconversion phosphors (UCPs), have demonstrated significant application potentials in some front fields, including solar energy conversion and bio-application. However, some bottleneck problems should be overcame, such as the lower upconversion efficiency, narrower excitation band, concentration-quenching and temperature-quenching. To solve these problems, the Ag-SiO2-Er2O3 nanocomposites were fabricated, in which the upconversion luminescence (UCL) of Er2O3 was white broadband. Through the interaction of Er2O3 with surface plasmon (SP) of silver nanoparticles (SNPs), the threshold power for generating broadbands was suppressed largely in contrast to the Er2O3 nanoparticles (NPs), while the UCL brightness was enhanced remarkably, ranging from several to 104 times, which strongly depended on the power density of excitation light. At excitation power density of 1.50 W/mm2 of 980 nm light, the UCL intensity of Ag-SiO2-Er2O3 is 40-folds than the well-known NaYF4:Yb3+,Er3+ commercial powders. And more, it is also interesting to observe that the composites demonstrate two excitation bands extending of 780–980 nm, highly improved UCL with elevated temperature and excitation power density. The UCL mechanism related to UCL enhancement was carefully studied. PMID:24867159

  11. Ag-SiO2-Er2O3 Nanocomposites: Highly Effective Upconversion Luminescence at High Power Excitation and High Temperature

    NASA Astrophysics Data System (ADS)

    Xu, Wen; Min, Xiaolei; Chen, Xu; Zhu, Yongsheng; Zhou, Pingwei; Cui, Shaobo; Xu, Sai; Tao, Li; Song, Hongwei

    2014-05-01

    Rare Earth (RE) activated upconversion phosphors (UCPs), have demonstrated significant application potentials in some front fields, including solar energy conversion and bio-application. However, some bottleneck problems should be overcame, such as the lower upconversion efficiency, narrower excitation band, concentration-quenching and temperature-quenching. To solve these problems, the Ag-SiO2-Er2O3 nanocomposites were fabricated, in which the upconversion luminescence (UCL) of Er2O3 was white broadband. Through the interaction of Er2O3 with surface plasmon (SP) of silver nanoparticles (SNPs), the threshold power for generating broadbands was suppressed largely in contrast to the Er2O3 nanoparticles (NPs), while the UCL brightness was enhanced remarkably, ranging from several to 104 times, which strongly depended on the power density of excitation light. At excitation power density of 1.50 W/mm2 of 980 nm light, the UCL intensity of Ag-SiO2-Er2O3 is 40-folds than the well-known NaYF4:Yb3+,Er3+ commercial powders. And more, it is also interesting to observe that the composites demonstrate two excitation bands extending of 780-980 nm, highly improved UCL with elevated temperature and excitation power density. The UCL mechanism related to UCL enhancement was carefully studied.

  12. High temperature polymers for proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Einsla, Brian Russel

    Novel proton exchange membranes (PEMs) were investigated that show potential for operating at higher temperatures in both direct methanol (DMFC) and H 2/air PEM fuel cells. The need for thermally stable polymers immediately suggests the possibility of heterocyclic polymers bearing appropriate ion conducting sites. Accordingly, monomers and random disulfonated poly(arylene ether) copolymers containing either naphthalimide, benzoxazole or benzimidazole moieties were synthesized via direct copolymerization. The ion exchange capacity (IEC) was varied by simply changing the ratio of disulfonated monomer to nonsulfonated monomer in the copolymerization step. Water uptake and proton conductivity of cast membranes increased with IEC. The water uptake of these heterocyclic copolymers was lower than that of comparable disulfonated poly(arylene ether) systems, which is a desirable improvement for PEMs. Membrane electrode assemblies were prepared and the initial fuel cell performance of the disulfonated polyimide and polybenzoxazole (PBO) copolymers was very promising at 80°C compared to the state-of-the-art PEM (NafionRTM); nevertheless these membranes became brittle under operating conditions. Several series of poly(arylene ether)s based on disodium-3,3'-disulfonate-4,4 '-dichlorodiphenylsulfone (S-DCDPS) and a benzimidazole-containing bisphenol were synthesized and afforded copolymers with enhanced stability. Selected properties of these membranes were compared to separately prepared miscible blends of disulfonated poly(arylene ether sulfone) copolymers and polybenzimidazole (PBI). Complexation of the sulfonic acid groups with the PBI structure reduced water swelling and proton conductivity. The enhanced proton conductivity of NafionRTM membranes has been proposed to be due to the aggregation of the highly acidic side-chain sulfonic acid sites to form ion channels. A series of side-chain sulfonated poly(arylene ether sulfone) copolymers based on methoxyhydroquinone was

  13. Nanocomposite-based rapid, visual, and selective luminescence turn-on assay for Hg2+ sensing in aqueous media.

    PubMed

    Cui, Jiabin; An, Mingyue; Wang, Leyu

    2013-10-15

    Composite nanospheres containing dithizone, luminescent LaVO4:Eu(3+) nanoparticles (NPs), and amphiphilic polymer have been composed for the rapid, selective, and visual luminescence turn-on detection of mercury ions (Hg(2+)) in water. Due to the absorption of dithizone, the strong red luminescence of LaVO4:Eu(3+) NPs encapsulated in nanospheres was quenched noticeably. As a result, these as-prepared nanocomposites (NCs) demonstrate very weak red luminescence. However, in the presence of Hg(2+), the red luminescence of nanocomposites was turned on dramatically, which can be attributed to the strong binding of mercury (II) ions by dithizone and forming a complex without absorption in the red emission range. Meanwhile, other cations have no influence on the detection of Hg(2+), suggesting a good selectivity for Hg(2+) sensing. Due to the high photostability and chemical stability of the nanocomposites, operation simplicity, low cost, and good selectivity, this newly developed method is highly desirable for field assay of Hg(2+) in aqueous media ranging from 40.0 nM to 4.0 μM with a limit of detection of 32.0 nM and a good linearity (r=0.9980). Therefore, a facile, rapid, selective, and visual luminescence turn-on technology has been successfully developed for Hg(2+) detection. PMID:24054626

  14. Material for a luminescent solar concentrator

    DOEpatents

    Andrews, L.J.

    1984-01-01

    A material for use in a luminescent solar concentrator, formed by ceramitizing the luminescent ion Cr/sup 3 +/ with a transparent ceramic glass containing mullite. The resultant material has tiny Cr/sup 3 +/-bearing crystallites dispersed uniformly through an amorphous glass. The invention combines the high luminescent efficiency of Cr/sup 3 +/ in the crystalline phase with the practical and economical advantages of glass technology.

  15. Morphology-Driven High-Performance Polymer Transistor-based Ammonia Gas Sensor.

    PubMed

    Yu, Seong Hoon; Cho, Jangwhan; Sim, Kyu Min; Ha, Jae Un; Chung, Dae Sung

    2016-03-01

    Developing high-performance gas sensors based on polymer field-effect transistors (PFETs) requires enhancing gas-capture abilities of polymer semiconductors without compromising their high charge carrier mobility. In this work, cohesive energies of polymer semiconductors were tuned by strategically inserting buffer layers, which resulted in dramatically different semiconductor surface morphologies. Elucidating morphological and structural properties of polymer semiconductor films in conjunction with FET studies revealed that surface morphologies containing large two-dimensional crystalline domains were optimal for achieving high surface areas and creating percolation pathways for charge carriers. Ammonia molecules with electron lone pairs adsorbed on the surface of conjugated semiconductors can serve as efficient trapping centers, which negatively shift transfer curves for p-type PFETs. Therefore, morphology optimization of polymer semiconductors enhances their gas sensing abilities toward ammonia, leading to a facile method of manufacturing high-performance gas sensors. PMID:26927929

  16. The selective synthesis of water-soluble highly luminescent CdTe nanoparticles and nanorods: The influence of the precursor Cd/Te molar ratio

    NASA Astrophysics Data System (ADS)

    Deng, Da-Wei; Qin, Yuan-Bin; Yang, Xi; Yu, Jun-Sheng; Pan, Yi

    2006-11-01

    In this report, we initially systematically investigated the influence of the precursor Cd/Te molar ratio on the morphology of water-soluble thiol-stabilized CdTe nanocrystals. By only changing the precursor Cd/Te molar ratio, highly luminescent CdTe nanoparticles (NPs) and nanorods (NRs) can be prepared selectively in the presence of the same concentration single ligand ( L-cysteine or thioglycolic acid) system. A high precursor Cd/Te molar ratio leads to isotropic spherical growth, whereas a low Cd/Te molar ratio promotes the linear self-assembly of NPs into NRs. Thus, a new efficient strategy has been developed in aqueous phase to prepare selectively highly luminescent dot- or rod-shaped CdTe nanocrystals in single ligand system. Then, we further explored the influence of the properties of initial CdTe dispersions with different luminescence maxima on the formation of NRs. The experiment results revealed that the formation of CdTe NRs is also dependent on the properties of initial CdTe dispersions. CdTe NPs with short wavelength emission (˜520-550 nm) can self-assemble directly into high quality CdTe NRs after storage at room temperature.

  17. Fixation of tritium in a highly stable polymer form

    DOEpatents

    Steinberg, Meyer; Colombo, Peter; Pruzansky, Jacob

    1977-01-01

    A method for the fixation of tritium comprising reacting tritiated water with calcium carbide to produce calcium hydroxide and tritiated acetylene, polymerizing the acetylene, and then incorporating the polymer in a solidifying matrix.

  18. Semi-2-interpenetrating polymer networks of high temperature systems

    NASA Technical Reports Server (NTRS)

    Hanky, A. O.; St. Clair, T. L.

    1985-01-01

    A semi-interpenetrating (semi-IPN) polymer system of the semi-2-IPN type is described in which a polymer of acetylene-terminated imidesulfone (ATPISO2) is cross linked in the presence of polyimidesulfone (PISO2). Six different formulations obtained by mixing of either ATPISO2-1n or ATPISO2-3n with PISO2 in three different proportions were characterized in terms of glass transition temperature, thermooxidative stability, inherent viscosity, and dynamic mechanical properties. Adhesive (lap shear) strength was tested at elevated temperatures on aged samples of adhesive scrim cloth prepared from each resin. Woven graphite (Celion 1000)/polyimide composites were tested for flexural strength, flexural modulus, and shear strength. The network polymers have properties intermediate between those of the component polymers alone, have greatly improved processability over either polyimide, and are able to form good adhesive bonds and composites, making the semi-2-IPN systems superior materials for aerospace structures.

  19. Preparation of biomimetic high adhesive superhydrophobic polymer pillar surfaces with crown-like metal microstructures.

    PubMed

    Ishii, Daisuke; Shimomura, Masatsugu

    2014-10-01

    High adhesive superhydrophobic polymer pillar surfaces with dispersed metallic crown-like micro structures were prepared by electroless plating on self-organized honeycomb patterned polymer films and peeling off the top layer of the metal covered honeycomb films. Thus obtained polymer pillar surfaces with metallic crown-like microstructures possessed conflicting properties of water repellency and adhesion. The adhesion property was tuned by number density of metallic crown-like microstructures which were adjusted by polymer concentration in a catalytic solution for electroless plating. PMID:25942835

  20. High effective atomic number polymer scintillators for gamma ray spectroscopy

    SciTech Connect

    Cherepy, Nerine Jane; Sanner, Robert Dean; Payne, Stephen Anthony; Rupert, Benjamin Lee; Sturm, Benjamin Walter

    2014-04-15

    A scintillator material according to one embodiment includes a bismuth-loaded aromatic polymer having an energy resolution at 662 keV of less than about 10%. A scintillator material according to another embodiment includes a bismuth-loaded aromatic polymer having a fluor incorporated therewith and an energy resolution at 662 keV of less than about 10%. Additional systems and methods are also presented.

  1. Thermophysical Properties of Polymer Materials with High Thermal Conductivity

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

    Results of studies on the main thermophysical properties of new thermally conductive polymer materials are presented. It is shown that modification of polymer dielectrics by micron-sized fillers allows thermally conductive materials with thermal conductivity not less than 2 W/(m K) to be produced, which makes it possible to use such materials as cooling elements of various electrical engineering and semiconductor equipment and devices.

  2. Water and polymer dynamics in highly crosslinked polyamide membranes

    NASA Astrophysics Data System (ADS)

    Frieberg, Bradley; Chan, Edwin; Tyagi, Madhu; Stafford, Christopher; Soles, Christopher

    Highly crosslinked polyamides for reverse osmosis are the state-of-the-art active material in membranes for desalination. The thin film composite membrane structure that is used commercially has been empirically designed to selectively allow the passage of water molecules and minimize the passage of solutes such as salt. However, due to the large roughness and variability of the polyamide layer, there is a limited understanding of the structure-property relationship for these materials as well as the transport mechanism. To better understand the water transport mechanism we measure the water and polymer dynamics of polyamide membranes using quasi-elastic neutron scattering (QENS). By hydrating the membrane with deuterated water, we are able to isolate the dynamics of the hydrogenated membrane on the pico- and nanosecond time scales. By subsequently hydrating the membranes with hydrogenated water, the QENS measurements on the same times scales reveal information about both the translational and rotational dynamics of water confined within the polyamide membrane. Further understanding of the water diffusion mechanism will establish design rules in which the performance of future membrane materials can be improved.

  3. Highly Conductive, Stretchable, and Transparent Solid Polymer Electrolyte Membrane

    NASA Astrophysics Data System (ADS)

    He, Ruixuan; Echeverri, Mauricio; Kyu, Thein

    2014-03-01

    With the guidance of ternary phase diagrams, completely amorphous polymer electrolyte membranes (PEM) were successfully prepared by melt processing for lithium-ion battery. The PEM under consideration consisted of poly (ethylene glycol diacrylate) (PEGDA), succinonitrile (SCN) and Lithium bis(trifluoro-methane)sulfonamide (LiTFSI). After UV-crosslinking, the PEM is transparent and light-weight. Addition of SCN plastic crystal affords not only dissociation of the lithium salt, but also plasticization to the crosslinked PEGDA network. Of particular importance is the achievement of room-temperature ionic conductivity of ~10-3 S/cm, which is comparable to that of commercial liquid electrolyte. Higher ionic conductivities were achieved at elevated temperatures or with use of a moderately higher molecular weight of PEGDA. In terms of electrochemical and chemical stability, the PEM exhibited oxidative stability up to 5 V against lithium reference electrode. Stable interface behavior between the PEM and lithium electrode is also seen with ageing time. In the tensile tests, samples containing low molecular weight PEGDA are stiffer, whereas the high molecular weight PEGDA is stretchable up to 80% elongation. Supported by NSF-DMR 1161070.

  4. Insights into the Mechanism and Kinetics of Thermo-Oxidative Degradation of HFPE High Performance Polymer.

    PubMed

    Kunnikuruvan, Sooraj; Parandekar, Priya V; Prakash, Om; Tsotsis, Thomas K; Nair, Nisanth N

    2016-06-01

    The growing requisite for materials having high thermo-oxidative stability makes the design and development of high performance materials an active area of research. Fluorination of the polymer backbone is a widely applied strategy to improve various properties of the polymer, most importantly the thermo-oxidative stability. Many of these fluorinated polymers are known to have thermo-oxidative stability up to 700 K. However, for space and aerospace applications, it is important to improve its thermo-oxidative stability beyond 700 K. Molecular-level details of the thermo-oxidative degradation of such polymers can provide vital information to improve the polymer. In this spirit, we have applied quantum mechanical and microkinetic analysis to scrutinize the mechanism and kinetics of the thermo-oxidative degradation of a fluorinated polymer with phenylethenyl end-cap, HFPE. This study gives an insight into the thermo-oxidative degradation of HFPE and explains most of the experimental observations on the thermo-oxidative degradation of this polymer. Thermolysis of C-CF3 bond in the dianhydride component (6FDA) of HFPE is found to be the rate-determining step of the degradation. Reaction pathways that are responsible for the experimentally observed weight loss of the polymer is also scrutinized. On the basis of these results, we propose a modification of HFPE polymer to improve its thermo-oxidative stability. PMID:27187246

  5. Accurate Cytotoxicity and Proliferation Determination: Advantages of a High-Throughput Phenotypic Approach Over ATP Luminescence Assays.

    PubMed

    Hammerstein, Anne F; Wylie, Paul G

    2016-09-01

    Cell viability and proliferation assays are a fundamental tool in the drug discovery process and are used to evaluate both the antiproliferative potency and toxicity of compounds. Some lead discovery groups generate cell viability data for up to two million compounds per screen, so any method used to assess these parameters needs to deliver not only on data quality but also on throughput and assay cost per well. Most methods used to determine cell viability cannot deliver on all three of these requirements, so compromises have to be made. Here we show the development and implementation of a cost-effective, no-wash phenotypic assay to simultaneously report the number of cells, percentage of live cells, and cell cycle phase distribution as markers of proliferation and viability. We demonstrate that this assay can be applied to high-density plate formats and be imaged and analyzed in 8 min per plate on a laser scanning imaging cytometer. By comparing the drug-responses of several well-characterized anticancer drugs on HeLa cells, we highlight the key differences between the phenotypic assay and a commercial ATP luminescence detection system. PMID:27504922

  6. Highly Luminescent Carbon Dots Synthesized by Microwave-Assisted Pyrolysis and Evaluation of Their Toxicity to Physa acuta.

    PubMed

    Sun, Xiaobo; Jin, Xiaozhe; Pan, Wei; Guo, Enmian; Liu, Weijian; Li, Denghui; Lu, Kunchao; Si, Shuxin; Zhang, Nianxing; Jia, Zhenzhen; Shi, Yanping; Li, Qianqian; Wang, Jinping

    2016-01-01

    As a newly emerging class of nanomaterials, carbon dots have increasingly attracted researchers' attention. However, their potentially adverse environmental effects are yet largely unknown. In this work, the highly luminescent carbon dots were synthesized by microwave-assisted pyrolysis of tris(hydroxymethyl)aminomethane (Tris) and citric acid. Then acute and chronic toxicities of carbon dots to Physa acuta (P. acuta), as well as their effect on reproduction, were evaluated using the as-synthesized dots as an example. The quantum yield of the as-synthesized carbon dots was up to 53.5% excited at 360 nm with the most fluorescent fraction of 82.6% after simple purification by gel column. The results showed that no acute but chronic toxicities to P. acuta exposed to different treatment concentrations of the as-synthesized carbon dots were observed with dose- dependence. In addition, the fecundity of P. acuta was promoted significantly by the carbon dots at the concentrations of 0.5 and 1.0 mg/mL, yet inhibited at the concentration of 3.0 mg/mL after 12-day exposure. Mainly distributing in the visceral mass might be responsible for the effects of the carbon dots on the survival and fecundity of P. acuta. And there was no further evidence to confirm that the carbon dots can cause malformation in developing embryos. PMID:27398502

  7. Facile microemulsion route to coat carbonized glucose on upconversion nanocrystals as high luminescence and biocompatible cell-imaging probes.

    PubMed

    Li, Zhengquan; Guo, Huichen; Qian, Haisheng; Hu, Yong

    2010-08-01

    Surface modification of lanthanide-doped upconversion nanocrystals is crucial to make them useful for various biological applications. Unfortunately, the current methods available to achieve a desirable surface exhibiting both high luminescence and good biocompatibility are limited. In this work, we present a facile microemulsion route to coat carbonized glucose on hydrophobic NaYF(4) nanocrystals. Owing to the particular structure of the carbonized shell, glucose coating on these UCNs is not only able to preserve strong fluorescence from the core nanocrystals, but it also confers good water solubility and bears various functional groups for conjugating to biomolecules. Compared to 10 nm silica-coated UCNs, these glucose-coated nanocrystals possess better cell biocompatibility, and can be rapidly internalized into cells. Such unique features of glucose-coated UCNs may find promising applications in imaging, diagnosis and therapeutic purposes. Besides, this facile surface-modification route has the potential to be extended to a broad range of other hydrophobic nanocrystals. PMID:20634574

  8. Hybrid luminescence materials assembled by [Ln(DPA)3]3− and mesoporous host through ion-pairing interactions with high quantum efficiencies and long lifetimes

    PubMed Central

    Li, Qing-Feng; Yue, Dan; Lu, Wei; Zhang, Xinlei; Li, Chunyang; Wang, Zhenling

    2015-01-01

    A kind of mesoporous hybrid luminescence material was assembled through the ion exchange method between [Ln(DPA)3]3− and ionic liquid functionalized SBA-15. [Ln(DPA)3]3− was successfully anchored onto positive-charge modified SBA-15 by the strong electrostatic interaction. In [Ln(DPA)3]3−, Ln3+ ions are in 9-fold coordination through six oxygen atoms of carboxyl groups and three nitrogen atoms of pyridine units, leaving no coordination site for water molecules. Therefore the hybrids possess prominent luminescent properties, SBA-15-IMI-Tb(DPA)3 and SBA-15-IMI-Eu(DPA)3 exhibit high quantum yield values of 63% and 79%, and long lifetimes values of 2.38 ms and 2.34 ms, respectively. Especially, SBA-15-IMI-Eu(DPA)3 presents a high color purity, and the red/orange intensity ratio is as high as 7.6. The excellent luminescence properties and ordered mesoporous structures give rise to many potential applications in optical and electronic areas. PMID:25669156

  9. Two volt, high power, high energy density rechargeable lithium polymer battery

    SciTech Connect

    Broadhead, J.

    1997-12-01

    Research and development of organo-sulfur polymer composite cathodes has produced a family of materials which are electroactive and rechargeable in nonaqueous systems. This publication describes the latest improvements in performance of AA cells and indicates directions to be taken for further development. Applications oriented performance characteristics (including high-rate charge and GSM pulse discharge) of AA cells are described. Initial Regulatory Agency abuse tests are outlined.

  10. Ferroelectric polymer networks with high energy density and improved discharged efficiency for dielectric energy storage.

    PubMed

    Khanchaitit, Paisan; Han, Kuo; Gadinski, Matthew R; Li, Qi; Wang, Qing

    2013-01-01

    Ferroelectric polymers are being actively explored as dielectric materials for electrical energy storage applications. However, their high dielectric constants and outstanding energy densities are accompanied by large dielectric loss due to ferroelectric hysteresis and electrical conduction, resulting in poor charge-discharge efficiencies under high electric fields. To address this long-standing problem, here we report the ferroelectric polymer networks exhibiting significantly reduced dielectric loss, superior polarization and greatly improved breakdown strength and reliability, while maintaining their fast discharge capability at a rate of microseconds. These concurrent improvements lead to unprecedented charge-discharge efficiencies and large values of the discharged energy density and also enable the operation of the ferroelectric polymers at elevated temperatures, which clearly outperforms the melt-extruded ferroelectric polymer films that represents the state of the art in dielectric polymers. The simplicity and scalability of the described method further suggest their potential for high energy density capacitors. PMID:24276519

  11. Record high hole mobility in polymer semiconductors via side-chain engineering.

    PubMed

    Kang, Il; Yun, Hui-Jun; Chung, Dae Sung; Kwon, Soon-Ki; Kim, Yun-Hi

    2013-10-01

    Charge carrier mobility is still the most challenging issue that should be overcome to realize everyday organic electronics in the near future. In this Communication, we show that introducing smart side-chain engineering to polymer semiconductors can facilitate intermolecular electronic communication. Two new polymers, P-29-DPPDBTE and P-29-DPPDTSE, which consist of a highly conductive diketopyrrolopyrrole backbone and an extended branching-position-adjusted side chain, showed unprecedented record high hole mobility of 12 cm(2)/(V·s). From photophysical and structural studies, we found that moving the branching position of the side chain away from the backbone of these polymers resulted in increased intermolecular interactions with extremely short π-π stacking distances, without compromising solubility of the polymers. As a result, high hole mobility could be achieved even in devices fabricated using the polymers at room temperature. PMID:24053786

  12. College-Mentored Polymer/Materials Science Modules for Middle and High School Students

    ERIC Educational Resources Information Center

    Lorenzini, Robert G.; Lewis, Maurica S.; Montclare, Jin Kim

    2011-01-01

    Polymers are materials with vast environmental and economic ramifications, yet are generally not discussed in secondary education science curricula. We describe a program in which college mentors develop and implement hands-on, polymer-related experiments to supplement a standard, state regents-prescribed high school chemistry course, as well as a…

  13. Degradation of Ultra-High Molar Mass Polymers in Size-Exclusion Chromatography

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The degradation of high molar mass polymers during size-exclusion chromatography (SEC) analysis has been a topic of interest for several decades. Should a polymer degrade during analysis, the accuracy of the molar mass (M) and architectural information obtained will be compromised. To this effect,...

  14. Effect of high-dose irradiation on the optically stimulated luminescence of Al2O3:C

    NASA Technical Reports Server (NTRS)

    Yukihara, E. G.; Whitley, V. H.; McKeever, S. W. S.; Akselrod, A. E.; Akselrod, M. S.

    2004-01-01

    This paper examines the effect of high-dose irradiation on the optically stimulated luminescence (OSL) of Al2O3:C, principally on the shape of the OSL decay curve and on the OSL sensitivity. The effect of the degree of deep trap filling on the OSL was also studied by monitoring the sensitivity changes after doses of beta irradiation and after step-annealing of samples previously irradiated with high doses. The OSL response to dose shows a linear-supralinear-saturation behavior, with a decrease in the response for doses higher than those required for saturation. This behavior correlates with the sensitivity changes observed in the samples annealed only to 773 K, which show sensitization for doses up to 20-50 Gy and desensitization for higher doses. Data from the step-annealing study leads to the suggestion that the sensitization is caused by the filling of deep electron traps, which become thermally unstable at 1100-1200 K, whereas the desensitization is caused by the filling of deep hole traps, which become thermally unstable at 800-875 K, along with a concomitant decrease in the concentration of recombination centers (F+ -centers). Changes in the shape of the OSL decay curves are also observed at high doses, the decay becoming faster as the dose increases. These changes in the OSL decay curves are discussed in terms of multiple overlapping components, each characterized by different photoionization cross-sections. However, using numerical solutions of the rate equations for a simple model consisting of a main trap and a recombination center, it is shown that the kinetics of OSL process may also be partially responsible for the changes in the OSL curves at high doses in Al2O3:C. Finally, the implication of these results for the dosimetry of heavy charged particles is discussed. c2004 Elsevier Ltd. All rights reserved.

  15. High Efficiency Hybrid Silicon Nanopillar-Polymer Solar Cells

    PubMed Central

    Pudasaini, Pushpa Raj; Ruiz-Zepeda, Francisco; Sharma, Manisha; Elam, David; Ponce, Arturo; Ayon, Arturo A

    2014-01-01

    Recently, inorganic/organic hybrid solar cells have been considered as a viable alternative for low-cost photovoltaic devices because the Schottky junction between inorganic and organic materials can be formed employing low temperature processing methods. We present an efficient hybrid solar cell based on highly ordered silicon nanopillars (SiNPs) and poly (3,4-ethylene-dioxythiophene):polystyrenesulfonate (PEDOT:PSS). The proposed device is formed by spin coating the organic polymer PEDOT:PSS on a SiNP array fabricated using metal assisted electroless chemical etching process. The characteristics of the hybrid solar cells are investigated as a function of SiNP height. A maximum power conversion efficiency (PCE) of 9.65% has been achieved for an optimized SiNP array hybrid solar cell with nanopillar height of 400 nm, despite the absence of a back surface field enhancement. The effect of an ultrathin atomic layer deposition (ALD), grown aluminum oxide (Al2O3), as a passivation layer (recombination barrier) has also been studied for the enhanced electrical performance of the device. With the inclusion of the ultrathin ALD deposited Al2O3 between the SiNP array textured surface and the PEDOT:PSS layer, the PCE of the fabricated device was observed to increase to 10.56%, which is ~10% greater than the corresponding device without the Al2O3 layer. The device described herein is considered to be promising toward the realization of a low-cost, high-efficiency inorganic/organic hybrid solar cell. PMID:24032746

  16. High efficiency hybrid silicon nanopillar-polymer solar cells.

    PubMed

    Pudasaini, Pushpa Raj; Ruiz-Zepeda, Francisco; Sharma, Manisha; Elam, David; Ponce, Arturo; Ayon, Arturo A

    2013-10-01

    Recently, inorganic/organic hybrid solar cells have been considered as a viable alternative for low-cost photovoltaic devices because the Schottky junction between inorganic and organic materials can be formed employing low temperature processing methods. We present an efficient hybrid solar cell based on highly ordered silicon nanopillars (SiNPs) and poly(3,4-ethylene-dioxythiophene):polystyrenesulfonate (PEDOT:PSS). The proposed device is formed by spin coating the organic polymer PEDOT:PSS on a SiNP array fabricated using metal assisted electroless chemical etching process. The characteristics of the hybrid solar cells are investigated as a function of SiNP height. A maximum power conversion efficiency (PCE) of 9.65% has been achieved for an optimized SiNP array hybrid solar cell with nanopillar height of 400 nm, despite the absence of a back surface field enhancement. The effect of an ultrathin atomic layer deposition (ALD), grown aluminum oxide (Al2O3), as a passivation layer (recombination barrier) has also been studied for the enhanced electrical performance of the device. With the inclusion of the ultrathin ALD deposited Al2O3 between the SiNP array textured surface and the PEDOT:PSS layer, the PCE of the fabricated device was observed to increase to 10.56%, which is ∼10% greater than the corresponding device without the Al2O3 layer. The device described herein is considered to be promising toward the realization of a low-cost, high-efficiency inorganic/organic hybrid solar cell. PMID:24032746

  17. The structures and luminescence properties of lanthanide (Ln = Sm, Eu and Tb) metal-organic coordination polymers based on 5-(2-hydroxyethoxy)isophthalate ligand

    NASA Astrophysics Data System (ADS)

    Wang, Peng; Zhang, Yu-Jie; Qin, Jie; Chen, Yong; Zhao, Ying

    2015-03-01

    Three unreported isomorphous Ln-containing metal-organic coordination polymeric complexes {LnL(HL)ṡ(H2O)2}n (Ln = Sm (1), Eu (2) and Tb (3), CCDC 971815-971817) were synthesized based on 5-(2-hydroxyethoxy) isophthalic acid (H2L) under hydrothermal conditions. The obtained coordination polymers were characterized by IR, elemental analysis, thermal analysis and X-ray diffraction In solid state, these polymers featured 3-D supramolecular structures constructed by 2-D sheets through H-bonds. Investigation of photoluminescence properties of H2L and 1-3 showed all of them exhibited intense fluorescent emissions in the solid state at room temperature.

  18. Highly Selective and Sensitive Luminescence Turn-On-Based Sensing of Al(3+) Ions in Aqueous Medium Using a MOF with Free Functional Sites.

    PubMed

    Singha, Debal Kanti; Mahata, Partha

    2015-07-01

    A new metal-organic framework [Co(OBA)(DATZ)0.5(H2O)] {OBA = 4,4'-oxybis(benzoic acid) and DATZ = 3,5-diamino-1,2,4-triazole}, 1, was synthesized by hydrothermal reaction. Single-crystal X-ray data of 1 confirmed two-dimensional rhombus grid network topology with a free nitrogen site of triazole ring and two amine groups of each DATZ. Photoluminescence study of 1 in aqueous medium shows blue emission at 407 nm upon excitation at 283 nm. This emissive property was used for the sensing of Al(3+) ions in aqueous medium through very high luminescence turn-on (6.3-fold) along with the blue shifting (∼24 nm) of the emission peak. However, luminescence studies in the presence of other common metal ions such as Mg(2+), Zn(2+), Ni(2+), Co(2+), Mn(2+), K(+), Na(+), Ca(2+), Cd(2+), Hg(2+), Cu(2+), Fe(2+), Fe(3+), and Cr(3+) in aqueous medium shows luminescence quenching in varying extent. Interestingly, the luminescence turn-on-based selectivity of Al(3+) ions in aqueous medium was achieved even in the presence of the highest quenchable metal ion, Fe(3+). Furthermore, very high sensitivity was observed in the case of Al(3+) ions with a limit of detection of Al(3+) of 57.5 ppb, which is significantly lower than the higher limit of U.S. Environmental Protection Agency recommendation of Al(3+) ion for drinking water (200 ppb). PMID:26052750

  19. Tailoring the dipole properties in dielectric polymers to realize high energy density with high breakdown strength and low dielectric loss

    SciTech Connect

    Thakur, Yash; Lin, Minren; Wu, Shan; Zhang, Q. M. E-mail: qxz1@psu.edu; Cheng, Zhaoxi; Jeong, D.-Y. E-mail: qxz1@psu.edu

    2015-03-21

    High energy density polymer materials are desirable for a broad range of modern power electronic systems. Here, we report the development of a new class of polymer dielectrics based on polyurea and polythiourea, which possess high thermal stability. By increasing the dipole density, the dielectric constant of meta-phenylene polyurea and methylene polythiourea can be increased to 5.7, compared with aromatic polyurea and aromatic polythiourea, which have a dielectric constant in the range of 4.1–4.3. The random dipoles with high dipolar moment and amorphous structure of these polyurea and polythiourea based polymers provide strong scattering to the charge carriers, resulting in low losses even at high electric fields. Consequently, this new class of polymers exhibit a linear dielectric response to the highest field measured (>700 MV/m) with a high breakdown strength, achieving high energy density (>13 J/cm{sup 3}) with high efficiency (>90%)

  20. Highly polarized emission of the liquid crystalline conjugated polymer by controlling the surface anchoring energy

    NASA Astrophysics Data System (ADS)

    In Jo, Soo; Kim, Youngsik; Baek, Ji-Ho; Yu, Chang-Jae; Kim, Jae-Hoon

    2014-01-01

    We demonstrated a highly polarized organic light-emitting diode (OLED) through the enhancement of the orientational ordering of the emitting polymer with a nematic liquid crystalline (LC) phase. The highly ordered state of the conjugate polymer was obtained by thermal annealing at the nematic temperature and strong azimuthal anchoring energy of the underlying polyimide. The order parameter of the conjugate polymer was analyzed using a second-harmonic generation model and the dichroic ratio was measured to be 22 : 1. Also, we applied our optimized OLED with high optical polarizability to an effective light source for a twisted nematic LC display.

  1. High sensitivity gas sensor based on high-Q suspended polymer photonic crystal nanocavity

    SciTech Connect

    Clevenson, Hannah Desjardins, Pierre; Gan, Xuetao; Englund, Dirk

    2014-06-16

    We present high-sensitivity, multi-use optical gas sensors based on a one-dimensional photonic crystal cavity. These devices are implemented in versatile, flexible polymer materials which swell when in contact with a target gas, causing a measurable cavity length change. This change causes a shift in the cavity resonance, allowing precision measurements of gas concentration. We demonstrate suspended polymer nanocavity sensors and the recovery of sensors after the removal of stimulant gas from the system. With a measured quality factor exceeding 10{sup 4}, we show measurements of gas concentration as low as 600 parts per million (ppm) and an experimental sensitivity of 10 ppm; furthermore, we predict detection levels in the parts-per-billion range for a variety of gases.

  2. Structural Design Parameters for Highly Birefringent Coordination Polymers.

    PubMed

    Thompson, John R; Katz, Michael J; Williams, Vance E; Leznoff, Daniel B

    2015-07-01

    A series of coordination polymer materials incorporating the highly anisotropic 2-(2-pyridyl)-1,10-phenanthroline (phenpy) building block have been synthesized and structurally characterized. M(phenpy)[Au(CN)2]2 (M = Cd, Mn) are isostructural and form a 1-D chain through bridging [Au(CN)2](-) units and extend into a 2-D sheet through aurophilic interactions. M(phenpy)(H2O)[Au(CN)2]2·2H2O (M = Cd, Mn, and Zn) are also isostructural but differ from the first set via the inclusion of a water molecule into the coordination sphere, resulting in a 1-D topology through aurophilic interactions. In(phenpy)(Cl)2[Au(CN)2]·0.5H2O forms a dimer through bridging chlorides and contains a free [Au(CN)2](-) unit. In the plane of the primary crystal growth direction, the birefringence values (Δn) of 0.37(2) (Cd(phenpy)[Au(CN)2]2), 0.50(3) (In(phenpy)(Cl)2[Au(CN)2]·0.5H2O), 0.56(3) and 0.59(6) (M(phenpy)(H2O)[Au(CN)2]2·2H2O M = Cd and Zn, respectively) were determined. β, a structural parameter defined by phenpy units rotated in the A-C plane relative to the light propagation (C) direction, was found to correlate to Δn magnitudes. The addition of a carbon-carbon double bond to terpy has increased the molecular polarizability anisotropy of the building block, and all structures have reduced deviation from planarity in comparison to terpy and terpy derivative structures, leading to these higher Δn values, which are among the highest reported for crystalline solids. PMID:26098267

  3. New infrared transmitting material via inverse vulcanization of elemental sulfur to prepare high refractive index polymers.

    PubMed

    Griebel, Jared J; Namnabat, Soha; Kim, Eui Tae; Himmelhuber, Roland; Moronta, Dominic H; Chung, Woo Jin; Simmonds, Adam G; Kim, Kyung-Jo; van der Laan, John; Nguyen, Ngoc A; Dereniak, Eustace L; Mackay, Michael E; Char, Kookheon; Glass, Richard S; Norwood, Robert A; Pyun, Jeffrey

    2014-05-21

    Polymers for IR imaging: The preparation of high refractive index polymers (n = 1.75 to 1.86) via the inverse vulcanization of elemental sulfur is reported. High quality imaging in the near (1.5 μm) and mid-IR (3-5 μm) regions using high refractive index polymeric lenses from these sulfur materials was demonstrated. PMID:24659231

  4. Luminescent macrocyclic lanthanide complexes

    DOEpatents

    Raymond, Kenneth N; Corneillie, Todd M; Xu, Jide

    2014-05-20

    The present invention provides a novel class of macrocyclic compounds as well as complexes formed between a metal (e.g., lanthanide) ion and the compounds of the invention. Preferred complexes exhibit high stability as well as high quantum yields of lanthanide ion luminescence in aqueous media without the need for secondary activating agents. Preferred compounds incorporate hydroxy-isophthalamide moieties within their macrocyclic structure and are characterized by surprisingly low, non-specific binding to a variety of polypeptides such as antibodies and proteins as well as high kinetic stability. These characteristics distinguish them from known, open-structured ligands.

  5. Luminescent macrocyclic lanthanide complexes

    DOEpatents

    Raymond, Kenneth N.; Corneillie, Todd M.; Xu, Jide

    2012-05-08

    The present invention provides a novel class of macrocyclic compounds as well as complexes formed between a metal (e.g., lanthanide) ion and the compounds of the invention. Preferred complexes exhibit high stability as well as high quantum yields of lanthanide ion luminescence in aqueous media without the need for secondary activating agents. Preferred compounds incorporate hydroxy-isophthalamide moieties within their macrocyclic structure and are characterized by surprisingly low, non-specific binding to a variety of polypeptides such as antibodies and proteins as well as high kinetic stability. These characteristics distinguish them from known, open-structured ligands.

  6. Synthesis, structure, thermostability and luminescence properties of Zn(II) and Cd(II) coordination polymers based on dimethysuccinate and flexible 1,4-bis(imidazol-1-ylmethyl)benzene ligands.

    PubMed

    Liu, Yang; Feng, Yong Lan; Fu, Wei Wei

    2016-09-01

    The design and synthesis of functional coordination polymers is motivated not only by their structural beauty but also by their potential applications. Zn(II) and Cd(II) coordination polymers are promising candidates for producing photoactive materials because these d(10) metal ions not only possess a variety of coordination numbers and geometries, but also exhibit luminescence properties when bound to functional ligands. It is difficult to predict the final structure of such polymers because the assembly process is influenced by many subtle factors. Bis(imidazol-1-yl)-substituted alkane/benzene molecules are good bridging ligands because their flexibility allows them to bend and rotate when they coordinate to metal centres. Two new Zn(II) and Cd(II) coordination polymers based on mixed ligands, namely, poly[[μ2-1,4-bis(imidazol-1-ylmethyl)benzene-κ(2)N(3):N(3')]bis(μ3-2,2-dimethylbutanoato-κ(3)O(1):O(4):O(4'))dizinc(II)], [Zn2(C6H8O4)2(C14H14N4)]n, and poly[[μ2-1,4-bis(imidazol-1-ylmethyl)benzene-κ(2)N(3):N(3')]bis(μ3-2,2-dimethylbutanoato-κ(5)O(1),O(1'):O(4),O(4'):O(4))dicadmium(II)], [Cd2(C6H8O4)2(C14H14N4)]n, have been synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction, elemental analysis, IR spectroscopy and thermogravimetric analysis. Both complexes crystallize in the monoclinic space group C2/c with similar unit-cell parameters and feature two-dimensional structures formed by the interconnection of S-shaped Zn(Cd)-2,2-dimethylsuccinate chains with 1,4-bis(imidazol-1-ylmethyl)benzene bridges. However, the Cd(II) and Zn(II) centres have different coordination numbers and the 2,2-dimethylsuccinate ligands display different coordination modes. Both complexes exhibit a blue photoluminescence in the solid state at room temperature. PMID:27585928

  7. Highly Oriented Polymer Field-Effect Transistors with High Electrical Stability

    NASA Astrophysics Data System (ADS)

    Endo, Toshiyuki; Nagase, Takashi; Kobayashi, Takashi; Naito, Hiroyoshi

    2013-12-01

    Oriented polymer field-effect transistors (FETs) with a top-gate configuration have been fabricated using amorphous fluoropolymers as gate insulators. The oriented poly(9,9-dioctylfluorene-co-bithiophene) (F8T2) FETs exhibit a high mobility anisotropy of 13 and a high mobility of 0.043 cm2.V-1.s-1 for charge transport parallel to the alignment direction. The temperature dependence of the mobility reveals small disorder in the oriented F8T2 microstructure at the interface with the fluoropolymer gate insulator. The transfer characteristics show no hysteresis or threshold voltage shift after applying a gate bias stress.

  8. Highly stable, luminescent core-shell type methylammonium-octylammonium lead bromide layered perovskite nanoparticles.

    PubMed

    Bhaumik, Saikat; Veldhuis, Sjoerd A; Ng, Yan Fong; Li, Mingjie; Muduli, Subas Kumar; Sum, Tze Chien; Damodaran, Bahulayan; Mhaisalkar, Subodh; Mathews, Nripan

    2016-06-01

    A new protocol for the synthesis of a highly stable (over 2 months under ambient conditions) solution-processed core-shell type structure of mixed methylammonium-octylammonium lead bromide perovskite nanoparticles (5-12 nm), having spherical shape, color tunability in the blue to green spectral region (438-521 nm) and a high photoluminescence quantum yield (PLQY) of up to 92% is described. The color tunability, high PLQY and stability are due to the quantum confinement imparted by the crystal engineering associated with core-shell nanoparticle formation during growth. PMID:27165565

  9. Achieving high performance polymer optoelectronic devices for high efficiency, long lifetime and low fabrication cost

    NASA Astrophysics Data System (ADS)

    Huang, Jinsong

    This thesis described three types of organic optoelectronic devices: polymer light emitting diodes (PLED), polymer photovoltaic solar cell, and organic photo detector. The research in this work focuses improving their performance including device efficiency, operation lifetime simplifying fabrication process. With further understanding in PLED device physics, we come up new device operation model and improved device architecture design. This new method is closely related to understanding of the science and physics at organic/metal oxide and metal oxide/metal interface. In our new device design, both material and interface are considered in order to confine and balance all injected carriers, which has been demonstrated very be successful in increasing device efficiency. We created two world records in device efficiency: 18 lm/W for white emission fluorescence PLED, 22 lm/W for red emission phosphorescence PLED. Slow solvent drying process has been demonstrated to significantly increase device efficiency in poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C 61-butyric acid methyl ester (PCBM) mixture polymer solar cell. From the mobility study by time of flight, the increase of efficiency can be well correlated to the improved carrier transport property due to P3HT crystallization during slow solvent drying. And it is found that, similar to PLED, balanced carrier mobility is essential in high efficient polymer solar cell. There is also a revolution in our device fabrication method. A unique device fabrication method is presented by an electronic glue based lamination process combined with interface modification as a one-step polymer solar cell fabrication process. It can completely skip the thermal evaporation process, and benefit device lifetime by several merits: no air reactive. The device obtained is metal free, semi-transparent, flexible, self-encapsulated, and comparable efficiency with that by regular method. We found the photomultiplication (PM) phenomenon in C

  10. Tailoring Dielectric Properties and Energy Density of Ferroelectric Polymer Nanocomposites by High-k Nanowires.

    PubMed

    Wang, Guanyao; Huang, Xingyi; Jiang, Pingkai

    2015-08-19

    High dielectric constant (k) polymer nanocomposites have shown great potential in dielectric and energy storage applications in the past few decades. The introduction of high-k nanomaterials into ferroelectric polymers has proven to be a promising strategy for the fabrication of high-k nanocomposites. One-dimensional large-aspect-ratio nanowires exhibit superiority in enhancing k values and energy density of polymer nanocomposites in comparison to their spherical counterparts. However, the impact of their intrinsic properties on the dielectric properties of polymer nanocomposites has been seldom investigated. Herein, four kinds of nanowires (Na2Ti3O7, TiO2, BaTiO3, and SrTiO3) with different inherent characteristics are elaborately selected to fabricate high-k ferroelectric polymer nanocomposites. Dopamine functionalization facilitates the excellent dispersion of these nanowires in the ferroelectric polymer matrix because of the strong polymer/nanowire interfacial adhesion. A thorough comparative study on the dielectric properties and energy storage capability of the nanowires-based nanocomposites has been presented. The results reveal that, among the four types of nanowires, BaTiO3 NWs show the best potential in improving the energy storage capability of the proposed nanocomposites, resulting from the most signficant increase of k while retaining the rather low dielectric loss and leakage current. PMID:26225887

  11. Preparation of soybean oil polymers with high molecular weight

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The cationic polymerization of soybean oils was initiated by boron trifluoride diethyl etherate BF3.O(C2H5)2 in supercritical carbon dioxide (scCO2) medium. The resulting polymers had molecular weight ranging from 21,842 to 118,300 g/mol. Nuclear magnetic resonance spectroscopy (NMR) and gel perme...

  12. Strategies, linkers and coordination polymers for high-performance sorbents

    DOEpatents

    Matzger, Adam J.; Wong-Foy, Antek G.; Lebel, Oliver

    2015-09-15

    A linking ligand compound includes three bidentate chemical moieties distributed about a central chemical moiety. Another linking ligand compound includes a bidentate linking ligand and a monodentate chemical moiety. Coordination polymers include a plurality of metal clusters linked together by residues of the linking ligand compounds.

  13. Studies of Radiation Effects in Three High Polymers

    NASA Astrophysics Data System (ADS)

    Ries, Heidi Rene-Mitchell

    Three high polymers, Mylar^circler , Ultem^circler, and Kapton^circler, were irradiated to total doses of 1, 5, and 9.5 gigarad using 1-MeV electrons. The glass transition temperatures ({rm T }_{rm g}) of the materials before and after irradiation were measured using an AC electrical dissipation factor technique. From the {rm T}_{rm g} data, it was found that the electron radiation at these total doses results in net chain scissioning in Mylar and net crosslinking in Ultem, while self-mending is predominant in Kapton. The dielectric constant was measured before and after irradiation, but no significant changes due to irradiation were observed. Electron paramagnetic resonance (EPR) was used to determine the total organic radical densities in the materials 0.5 hr after irradiation. Total organic radical densities of approximately 10^{18 } spins/g were recorded in all three materials. Additional postirradiation EPR radical density measurements were made at later times to determine the radical decay rates. The radical decay rates were highly varied and did not conform to first-order or second-order decay kinetics, due to the simultaneous presence of several different radical species. Utilizing the EPR spectra, postirradiation radical identifications were made for all three materials. The predominant radicals in Mylar were a phenyl radical and a carbonyl radical, both resulting from a main chain C-C bond scission. In Ultem, an ethylene radical due to a C-C bond scission in the crosslinked material is observed. In Kapton, phenyl and phenoxyl radicals are present resulting from the scission of an ether linkage. Ketone radicals due to the opening of imide rings are also present in Kapton. At long postirradiation times, peroxy radicals are present in all three materials. DC conductivity was measured before and 0.5 hr after irradiation, as well as at longer postirradiation times. Kapton exhibited a 5-order of magnitude increase in conductivity following irradiation, whereas

  14. Ionic liquid as plasticizer for europium(III)-doped luminescent poly(methyl methacrylate) films.

    PubMed

    Lunstroot, Kyra; Driesen, Kris; Nockemann, Peter; Viau, Lydie; Mutin, P Hubert; Vioux, André; Binnemans, Koen

    2010-02-28

    Flexible luminescent polymer films were obtained by doping europium(III) complexes in blends of poly(methyl methacrylate) (PMMA) and the ionic liquid 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C(6)mim][Tf(2)N]. Different europium(III) complexes have been incorporated in the polymer/ionic liquid matrix: [C(6)mim][Eu(nta)(4)], [C(6)mim][Eu(tta)(4)], [Eu(tta)(3)(phen)] and [choline](3)[Eu(dpa)(3)], where nta is 2-naphthoyltrifluoroacetonate, tta is 2-thenoyltrifluoroacetonate, phen is 1,10-phenanthroline, dpa is 2,6-pyridinedicarboxylate (dipicolinate) and choline is the 2-hydroxyethyltrimethyl ammonium cation. Bright red photoluminescence was observed for all the films upon irradiation with ultraviolet radiation. The luminescent films have been investigated by high-resolution steady-state luminescence spectroscopy and by time-resolved measurements. The polymer films doped with beta-diketonate complexes are characterized by a very intense (5)D(0)-->(7)F(2) transition (up to 15 times more intense than the (5)D(0)-->(7)F(1)) transition, whereas a marked feature of the PMMA films doped with [choline](3)[Eu(dpa)(3)] is the long lifetime of the (5)D(0) excited state (1.8 ms). PMID:20145855

  15. Implant- and Tooth-Supported Fixed Prostheses Using a High-Performance Polymer (Pekkton) Framework.

    PubMed

    Han, Kyeong-Hwan; Lee, Jeong-Yol; Shin, Sang Wan

    2016-01-01

    The type of prosthetic restoration used in implant rehabilitation greatly contributes to the recovery of masticatory function as well as quality of life in patients. Frameworks for implant-supported prostheses are typically made by casting metal or milling either titanium or zirconia. Recently, nonmetal, polymer-type materials were suggested as framework materials. Polyetherketoneketone (PEKK), a high-performance polymer, was recently introduced in the dental field with potentially wide-ranging applications. This case history report describes implant- and tooth-supported fixed prostheses created using a new high performance polymer (Pekkton, Cendres+Metaux) framework for a fully edentulous maxilla and partially edentulous mandible. PMID:27611747

  16. Highly ductile UV-shielding polymer composites with boron nitride nanospheres as fillers

    NASA Astrophysics Data System (ADS)

    Fu, Yuqiao; Huang, Yan; Meng, Wenjun; Wang, Zifeng; Bando, Yoshio; Golberg, Dmitri; Tang, Chengchun; Zhi, Chunyi

    2015-03-01

    Polymer composites with enhanced mechanical, thermal or optical performance usually suffer from poor ductility induced by confined mobility of polymer chains. Herein, highly ductile UV-shielding polymer composites are successfully fabricated. Boron nitride (BN) materials, with a wide band gap of around ∼6.0 eV, are used as fillers to achieve the remarkably improved UV-shielding performance of a polymer matrix. In addition, it is found that spherical morphology BN as a filler can keep the excellent ductility of the composites. For a comparison, it is demonstrated that traditional fillers, including conventional BN powders can achieve the similar UV-shielding performance but dramatically decrease the composite ductility. The mechanism behind this phenomenon is believed to be lubricant effects of BN nanospheres for sliding of polymer chains, which is in consistent with the thermal analyses. This study provides a new design to fabricate UV-shielding composite films with well-preserved ductility.

  17. Peptides Displayed as High Density Brush Polymers Resist Proteolysis and Retain Bioactivity

    PubMed Central

    2015-01-01

    We describe a strategy for rendering peptides resistant to proteolysis by formulating them as high-density brush polymers. The utility of this approach is demonstrated by polymerizing well-established cell-penetrating peptides (CPPs) and showing that the resulting polymers are not only resistant to proteolysis but also maintain their ability to enter cells. The scope of this design concept is explored by studying the proteolytic resistance of brush polymers composed of peptides that are substrates for either thrombin or a metalloprotease. Finally, we demonstrate that the proteolytic susceptibility of peptide brush polymers can be tuned by adjusting the density of the polymer brush and offer in silico models to rationalize this finding. We contend that this strategy offers a plausible method of preparing peptides for in vivo use, where rapid digestion by proteases has traditionally restricted their utility. PMID:25314576

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    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.

  19. Novel Stable Gel Polymer Electrolyte: Toward a High Safety and Long Life Li-Air Battery.

    PubMed

    Yi, Jin; Liu, Xizheng; Guo, Shaohua; Zhu, Kai; Xue, Hailong; Zhou, Haoshen

    2015-10-28

    Nonaqueous Li-air battery, as a promising electrochemical energy storage device, has attracted substantial interest, while the safety issues derived from the intrinsic instability of organic liquid electrolytes may become a possible bottleneck for the future application of Li-air battery. Herein, through elaborate design, a novel stable composite gel polymer electrolyte is first proposed and explored for Li-air battery. By use of the composite gel polymer electrolyte, the Li-air polymer batteries composed of a lithium foil anode and Super P cathode are assembled and operated in ambient air and their cycling performance is evaluated. The batteries exhibit enhanced cycling stability and safety, where 100 cycles are achieved in ambient air at room temperature. The feasibility study demonstrates that the gel polymer electrolyte-based polymer Li-air battery is highly advantageous and could be used as a useful alternative strategy for the development of Li-air battery upon further application. PMID:26452054

  20. Optimization of molecular organization and nanoscale morphology for high performance low bandgap polymer solar cells

    NASA Astrophysics Data System (ADS)

    He, Ming; Wang, Mengye; Lin, Changjian; Lin, Zhiqun

    2014-03-01

    Rational design and synthesis of low bandgap (LBG) polymers with judiciously tailored HOMO and LUMO levels have emerged as a viable route to high performance polymer solar cells with power conversion efficiencies (PCEs) exceeding 10%. In addition to engineering the energy-level of LBG polymers, the photovoltaic performance of LBG polymer-based solar cells also relies on the device architecture, in particular the fine morphology of the photoactive layer. The nanoscale interpenetrating networks composed of nanostructured donor and acceptor phases are the key to providing a large donor-acceptor interfacial area for maximizing the exciton dissociation and offering a continuous pathway for charge transport. In this Review Article, we summarize recent strategies for tuning the molecular organization and nanoscale morphology toward an enhanced photovoltaic performance of LBG polymer-based solar cells.

  1. Structure and luminescence behaviour of as-synthesized, calcined, and restored MgAlEu-LDH with high crystallinity.

    PubMed

    Zhao, Yushuang; Li, Ji-Guang; Fang, Fang; Chu, Nankai; Ma, Hui; Yang, Xiaojing

    2012-10-21

    Highly crystalline Eu(3+)-incorporated MgAl layered double hydroxides (LDHs) were synthesized by the homogeneous precipitation method. For the crystals as-prepared, after their calcination from 200-1000 °C, and, further, after restoration in a Na(2)CO(3) solution, the structural and luminescent changes were investigated for the first time. Eu(3+) ions with a coordination number of, probably, 8, were incorporated into the hydrotalcite layer, which led to a basal spacing (d(basal)) increase, microstrain formation, and crystalline morphology imperfections, while retaining the original lattice symmetry, R3[combining macron]m. In the deconstruction process due to calcination, the Eu(3+) ions restrained the formation of the spinel phase from the layered double oxide (LDO), but did not significantly change the memory effect, by which LDOs can convert to LDHs during the hydration process. For the reversible phase transformation between LDH and LDO, the morphology observation revealed that, in addition to the formation of pores on the surface, nano-slabs were formed, especially for the restored crystals. A layered phase with a d(basal) of 5.8 Å, due to bridging bidentate carbonates with the hydrotalcite layer, was formed in the calcination process at low temperature (300 °C) before the formation of LDO, but could not be restored to a large spacing. Typical (5)D(0) → (7)F(J) (J = 0-4) transitions of Eu(3+) at 579, 593, 615, 653, and 698 nm were observed in the photoluminescence spectra and the intensity of the dominating 615 nm band decreased with the LDH deconstruction and the formation of free water, and then increased with the formation of LDOs in the calcination process, and vice versa in the reconstruction process. The Eu(3+) ions had a probable 9- or 10-coordination mode in addition to the probable 8-coordination mode as the spinel phase appeared. PMID:22930336

  2. Deformable membranes actuated by high mechanical power density composite electroactive polymers using tailored electric field

    NASA Technical Reports Server (NTRS)

    Bar-Cohen, Y.; Bhattacharya, K.

    2003-01-01

    The objective of the project was to develop a versatile electroactuator based on a specific class of EAP, conductive polymer, that is capable of developing high forces and displacements in both bending and linear contraction/expansion movements.

  3. Spontaneous aggregation of lithium ion coordination polymers in fluorinated electrolytes for high-voltage batteries

    DOE PAGESBeta

    Malliakas, Christos D.; Leung, Kevin; Pupek, Krzysztof Z.; Shkrob, Ilya A.; Abraham, Daniel P.

    2016-03-31

    Fluorinated carbonate solvents are pursued as liquid electrolytes for high-voltage Li-ion batteries. We report aggregation of [Li+(FEC)3]n polymer species from fluoroethylene carbonate containing electrolytes and scrutinized the causes for this behavior.

  4. Carbon-13 Labeling Used to Probe Cure and Degradation Reactions of High- Temperature Polymers

    NASA Technical Reports Server (NTRS)

    Meador, Mary Ann B.; Johnston, J. Christopher

    1998-01-01

    High-temperature, crosslinked polyimides are typically insoluble, intractible materials. Consequently, in these systems it has been difficult to follow high-temperature curing or long-term degradation reactions on a molecular level. Selective labeling of the polymers with carbon-13, coupled with solid nuclear magnetic resonance spectrometry (NMR), enables these reactions to be followed. We successfully employed this technique to provide insight into both curing and degradation reactions of PMR-15, a polymer matrix resin used extensively in aircraft engine applications.

  5. Imaging Carbon Nanotubes in High Performance Polymer Composites via Magnetic Force Microscope

    NASA Technical Reports Server (NTRS)

    Lillehei, Peter T.; Park, Cheol; Rouse, Jason H.; Siochi, Emilie J.; Bushnell, Dennis M. (Technical Monitor)

    2002-01-01

    Application of carbon nanotubes as reinforcement in structural composites is dependent on the efficient dispersion of the nanotubes in a high performance polymer matrix. The characterization of such dispersion is limited by the lack of available tools to visualize the quality of the matrix/carbon nanotube interaction. The work reported herein demonstrates the use of magnetic force microscopy (MFM) as a promising technique for characterizing the dispersion of nanotubes in a high performance polymer matrix.

  6. Design and synthesis of polymer, carbon and composite electrodes for high energy and high power supercapacitors

    NASA Astrophysics Data System (ADS)

    Arcila Velez, Margarita Rosa

    Supercapacitors (SCs) are promising energy storage devices because they deliver energy faster than Li-ion batteries and store larger amounts of charge compared to dielectric capacitors. SCs are classified in electrical double layer capacitors (EDLCs) and pseudocapacitors, based on their charge storage mechanism. EDLCs store charge electrostatically, i.e. by physical charge separation. This mechanism limits the storable amount of energy to the available surface area of the electrode, typically made of carbon materials, but grants good cycling stability of the SC device. Pseudocapacitor electrodes, commonly made of conducting polymers or metal oxides, store charge faradaically, i.e. through redox reactions throughout the bulk material, which allows them to store significantly larger amounts of energy than EDLCs, but their stability is compromised due to the partial irreversibility of the faradaic processes. To accomplish the commercialization of SCs, devices must show a combination of high charge storage capacities and long-term stability, besides being cost-effective. To tackle the current issues of SCs, this field of study has taken mainly two directions: 1) the development of new architectures and nanostructures of the active materials, which has shown to increase the surface area, enhance stability, and facilitate ion diffusion; and 2) fabrication of composites between non-faradaic (carbon), faradaic materials, and/or redox-active components to achieve a balance between the amount of energy stored and the stability. Following the first approach, a continuous process to grow vertically aligned carbon nanotubes (VACNTs) on cost-effective aluminum foil was developed. The resulting electrodes were analyzed as SC electrodes and in symmetric cells, and the influence of the arrangement of the nanotubes and the synthesis conditions was studied. The performance of the VACNTs produced continuously showed similar performance to the VACNTs produced stationarily and the

  7. High-Field-Effect Mobility of Low-Crystallinity Conjugated Polymers with Localized Aggregates.

    PubMed

    Son, Sung Y; Kim, Yebyeol; Lee, Junwoo; Lee, Gang-Young; Park, Won-Tae; Noh, Yong-Young; Park, Chan E; Park, Taiho

    2016-07-01

    Charge carriers typically move faster in crystalline regions than in amorphous regions in conjugated polymers because polymer chains adopt a regular arrangement resulting in a high degree of π-π stacking in crystalline regions. In contrast, the random polymer chain orientation in amorphous regions hinders connectivity between conjugated backbones; thus, it hinders charge carrier delocalization. Various studies have attempted to enhance charge carrier transport by increasing crystallinity. However, these approaches are inevitably limited by the semicrystalline nature of conjugated polymers. Moreover, high-crystallinity conjugated polymers have proven inadequate for soft electronics applications because of their poor mechanical resilience. Increasing the polymer chain connectivity by forming localized aggregates via π-orbital overlap among several conjugated backbones in amorphous regions provides a more effective approach to efficient charge carrier transport. A simple strategy relying on the density of random copolymer alkyl side chains was developed to generate these localized aggregates. In this strategy, steric hindrance caused by these side chains was modulated to change their density. Interestingly, a random polymer exhibiting low alkyl side chain density and crystallinity displayed greatly enhanced field-effect mobility (1.37 cm(2)/(V·s)) compared with highly crystalline poly(3-hexylthiophene). PMID:27149835

  8. Polar-solvent-free colloidal synthesis of highly luminescent alkylammonium lead halide perovskite nanocrystals.

    PubMed

    Vybornyi, Oleh; Yakunin, Sergii; Kovalenko, Maksym V

    2016-03-17

    A novel synthesis of hybrid organic-inorganic lead halide perovskite nanocrystals (CH3NH3PbX3, X = Br or I) that does not involve the use of dimethylformamide or other polar solvents is presented. The reaction between methylamine and PbX2 salts is conducted in a high-boiling nonpolar solvent (1-octadecene) in the presence of oleylamine and oleic acid as coordinating ligands. The resulting nanocrystals are characterized by high photoluminescence quantum efficiencies of 15-50%, outstanding phase purity and tunable shapes (nanocubes, nanowires, and nanoplatelets). Nanoplatelets spontaneously assemble into micrometer-length wires by face-to-face stacking. In addition, we demonstrate amplified spontaneous emission from thin films of green-emitting CH3NH3PbBr3 nanowires with low pumping thresholds of 3 μJ cm(-2). PMID:26645348

  9. High ampacity, thin-wall, novel polymer cable. Final report

    SciTech Connect

    Jayaraj, K.

    1998-12-01

    Utilities are constantly faced with the challenge of providing higher ampacity cables that will fit into existing ducts in the cities. Therefore, a need exists to develop extruded cables that have a thinner insulation than conventional cables to provide the capability of installing higher ampacity cables into existing ducts. The goal of this project was to identify commercially available advanced polymers that are suitable for use in extruded distribution cables. The project consists of three tasks; this report describes the results of these tasks. In Task 1, a literature and vendor survey was conducted to identify candidate insulation materials. The mechanical and electrical properties of the candidates were measured in Task 2, yielding the following experimental results: all of the materials exhibited acceptable tensile strength values. LCP candidates, Vectra and HX6000, and Ultem exhibited very small elongation of less than 10%. Because of their high strength, cables with LCP insulation are too stiff to be bent or reeled at the required insulation thicknesses. This finding eliminated the LCP materials, Vectra and HX6000, from consideration. The dielectric constant of all of the materials was close to or below the benchmark of 3.5 at room temperature. However, the loss factors at 60 Hz of Ultem and PEEK exceeded the criterion of 0.001. Room temperature dielectric strengths of 20 mil thick specimens of Ultem and PEEK and 16 mil films of Aurum were 1600, 1100 and 1400 V/mil respectively. Based on these experimental results, Ultem, PEEK and Aurum, were selected for further evaluations. To reduce the costs and improve the ductility, Aurum and PEEK were blended with 50% and 30% Ultem respectively. The three neat materials and two blends were extruded onto single strand copper conductor at BICC. Three sets of extrusion trials were conducted to improve the quality of the extruded insulation. Although tremendous progress was achieved during the course of the project

  10. Polar-solvent-free colloidal synthesis of highly luminescent alkylammonium lead halide perovskite nanocrystals

    NASA Astrophysics Data System (ADS)

    Vybornyi, Oleh; Yakunin, Sergii; Kovalenko, Maksym V.

    2016-03-01

    A novel synthesis of hybrid organic-inorganic lead halide perovskite nanocrystals (CH3NH3PbX3, X = Br or I) that does not involve the use of dimethylformamide or other polar solvents is presented. The reaction between methylamine and PbX2 salts is conducted in a high-boiling nonpolar solvent (1-octadecene) in the presence of oleylamine and oleic acid as coordinating ligands. The resulting nanocrystals are characterized by high photoluminescence quantum efficiencies of 15-50%, outstanding phase purity and tunable shapes (nanocubes, nanowires, and nanoplatelets). Nanoplatelets spontaneously assemble into micrometer-length wires by face-to-face stacking. In addition, we demonstrate amplified spontaneous emission from thin films of green-emitting CH3NH3PbBr3 nanowires with low pumping thresholds of 3 μJ cm-2.A novel synthesis of hybrid organic-inorganic lead halide perovskite nanocrystals (CH3NH3PbX3, X = Br or I) that does not involve the use of dimethylformamide or other polar solvents is presented. The reaction between methylamine and PbX2 salts is conducted in a high-boiling nonpolar solvent (1-octadecene) in the presence of oleylamine and oleic acid as coordinating ligands. The resulting nanocrystals are characterized by high photoluminescence quantum efficiencies of 15-50%, outstanding phase purity and tunable shapes (nanocubes, nanowires, and nanoplatelets). Nanoplatelets spontaneously assemble into micrometer-length wires by face-to-face stacking. In addition, we demonstrate amplified spontaneous emission from thin films of green-emitting CH3NH3PbBr3 nanowires with low pumping thresholds of 3 μJ cm-2. Electronic supplementary information (ESI) available: Materials and methods, additional figures. See DOI: 10.1039/c5nr06890h

  11. Surface pressure field mapping using luminescent coatings

    NASA Technical Reports Server (NTRS)

    Mclachlan, B. G.; Kavandi, J. L.; Callis, J. B.; Gouterman, M.; Green, E.; Khalil, G.; Burns, D.

    1993-01-01

    In recent experiments we demonstrated the feasibility of using the oxygen dependence of luminescent molecules for surface pressure measurement in aerodynamic testing. This technique is based on the observation that for many luminescent molecules the light emitted increases as the oxygen partial pressure, and thus the air pressure, the molecules see decreases. In practice the surface to be observed is coated with an oxygen permeable polymer containing a luminescent molecule and illuminated with ultraviolet radiation. The airflow induced surface pressure field is seen as a luminescence intensity distribution which can be measured using quantitative video techniques. Computer processing converts the video data into a map of the surface pressure field. The experiments consisted of evaluating a trial luminescent coating in measuring the static surface pressure field over a two-dimensional NACA-0012 section model airfoil for Mach numbers ranging from 0.3 and 0.66. Comparison of the luminescent coating derived pressures were made to those obtained from conventional pressure taps. The method along with the experiment and its results will be described.

  12. Lignin-based monomers: Utilization in high-performance polymers and the effects of their structures on polymer properties

    NASA Astrophysics Data System (ADS)

    Stanzione, Joseph F., III

    With the uncertainty of petroleum reserves and future crude oil prices, lignocellulosic biomass is becoming an increasingly valuable resource for the sustainable development of fuels, chemicals, and materials, including vinyl ester resins (VERs). Petroleum-based VERs are used to produce polymer composites for a wide variety of commercial applications. Although possessing relatively high moduli, strengths, and glass transition temperatures, commercial VERs typically contain high concentrations of a reactive diluent, such as styrene. However, these reactive diluents are often considered hazardous air pollutants (HAPs), volatile organic compounds (VOCs), and anticipated carcinogens. Moreover, bisphenol-A, which has gained considerable attention due to potential associated health-related issues, is utilized as a precursor in the synthesis of VERs. A green chemistry and engineering approach in the development of new VERs and renewable reactive diluents that are based on lignin is presented in this dissertation. Lignin, which is currently an abundant, renewable waste product of the paper and pulping industry, is primarily burned as a low value fuel. However, lignin has the potential to be a low cost feedstock in future lignocellulosic biorefineries that could yield highly valuable aromatic chemicals (lignin model compounds, LMCs) when strategically depolymerized. The incorporation of aromaticity in a resin's chemical structure is known to improve overall polymer composite performance and the high aromatic content found in lignin is ideal for novel resin development. Highlighted in this dissertation are three projects: (1) the synthesis and characterization of a lignin-based bio-oil resin/reactive diluent, (2) the use of functionalized LMCs as styrene replacements in VERs, and (3) the synthesis and characterization of a vanillin-based resin. Through the use of traditional and new polymer theory coupled with spectroscopic, thermal, and mechanical techniques, structure

  13. Highly emissive PEG-encapsulated conjugated polymer nanoparticles

    NASA Astrophysics Data System (ADS)

    Li, Yuqiong; Liu, Jie; Liu, Bin; Tomczak, Nikodem

    2012-08-01

    A novel bioimaging probe based on a conjugated polymer, poly(9,9-dihexylfluorene-alt-2,1,3-benzoxadiazole) (PFBD), is demonstrated. Transfer of the hydrophobic polymer into water using a short chain poly(ethylene glycol) (PEG) resulted in conjugated polymer nanoparticles (PEG-PFBD) with a fluorescence quantum yield of 46%. The PEG-PFBD nanoparticles possessed several desirable structural and photophysical properties, such as colloidal stability in a broad range of pH values, sub-20 nm particle size, the presence of surface chemical functionality, as well as desirable excitation and emission spectra, for bioimaging applications. PEG-PFBD nanoparticles were conjugated with cyclic RGDfK targeting peptide for labeling of membrane αVβ3 integrin receptors on live HT-29 adenocarcinoma cells. Single nanoparticle microscopy revealed that the PEG-capped PFBD nanoparticles exhibit at least ten times higher emitted photon counts than single quantum dots (QD655) of comparable size. In addition, Fluorescence Lifetime Imaging Microscopy (FLIM) of single PEG-PFBD nanoparticles revealed that the nanoparticles display a clearly resolvable single nanoparticle fluorescence lifetime.A novel bioimaging probe based on a conjugated polymer, poly(9,9-dihexylfluorene-alt-2,1,3-benzoxadiazole) (PFBD), is demonstrated. Transfer of the hydrophobic polymer into water using a short chain poly(ethylene glycol) (PEG) resulted in conjugated polymer nanoparticles (PEG-PFBD) with a fluorescence quantum yield of 46%. The PEG-PFBD nanoparticles possessed several desirable structural and photophysical properties, such as colloidal stability in a broad range of pH values, sub-20 nm particle size, the presence of surface chemical functionality, as well as desirable excitation and emission spectra, for bioimaging applications. PEG-PFBD nanoparticles were conjugated with cyclic RGDfK targeting peptide for labeling of membrane αVβ3 integrin receptors on live HT-29 adenocarcinoma cells. Single

  14. Novel nature-inspired conjugated polymers for high performance transistors and solar cells (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Bronstein, Hugo A.; Falon, Kealan; Yaacobi-Gross, Nir; Ashraf, Raja Shahid; McCulloch, Iain; Anthopoulos, Thomas D.

    2015-10-01

    Novel, extremely narrow band-gap polymer with a structure based on natural indigo has been synthesised and exhibits high crystallinity, high ambipolar transport in OFET devices, and OPV device efficiencies up to 2.35% with light absorbance up to 950 nm, demonstrating potential in near-IR photovoltaics. We demonstrate that the use of a potentially bio-sustainable monomer unit in a conjugated polymer can give balanced ambipolar OFET mobilities in excess of 0.5 cm2/Vs. This novel monomer, and polymers are synthesized by rigidifying the structure of indigo by condensation with an aromatic acidic acid. The materials display high crystallinity which can be further enhanced by annealing and demonstrate that it can be used as a potentially biosustainable alternative to the commonly used DPP and iso-indigo monomers. We believe this is the first attempt to tackle the issue of sustainability in conjugated polymer synthesis.

  15. High elastic modulus polymer electrolytes suitable for preventing thermal runaway in lithium batteries

    DOEpatents

    Mullin, Scott; Panday, Ashoutosh; Balsara, Nitash Pervez; Singh, Mohit; Eitouni, Hany Basam; Gomez, Enrique Daniel

    2014-04-22

    A polymer that combines high ionic conductivity with the structural properties required for Li electrode stability is useful as a solid phase electrolyte for high energy density, high cycle life batteries that do not suffer from failures due to side reactions and dendrite growth on the Li electrodes, and other potential applications. The polymer electrolyte includes a linear block copolymer having a conductive linear polymer block with a molecular weight of at least 5000 Daltons, a structural linear polymer block with an elastic modulus in excess of 1.times.10.sup.7 Pa and an ionic conductivity of at least 1.times.10.sup.-5 Scm.sup.-1. The electrolyte is made under dry conditions to achieve the noted characteristics. In another aspect, the electrolyte exhibits a conductivity drop when the temperature of electrolyte increases over a threshold temperature, thereby providing a shutoff mechanism for preventing thermal runaway in lithium battery cells.

  16. High Luminescence Efficiency in MoS2 Grown by Chemical Vapor Deposition.

    PubMed

    Amani, Matin; Burke, Robert A; Ji, Xiang; Zhao, Peida; Lien, Der-Hsien; Taheri, Peyman; Ahn, Geun Ho; Kirya, Daisuke; Ager, Joel W; Yablonovitch, Eli; Kong, Jing; Dubey, Madan; Javey, Ali

    2016-07-26

    One of the major challenges facing the rapidly growing field of two-dimensional (2D) transition metal dichalcogenides (TMDCs) is the development of growth techniques to enable large-area synthesis of high-quality materials. Chemical vapor deposition (CVD) is one of the leading techniques for the synthesis of TMDCs; however, the quality of the material produced is limited by defects formed during the growth process. A very useful nondestructive technique that can be utilized to probe defects in semiconductors is the room-temperature photoluminescence (PL) quantum yield (QY). It was recently demonstrated that a PL QY near 100% can be obtained in MoS2 and WS2 monolayers prepared by micromechanical exfoliation by treating samples with an organic superacid: bis(trifluoromethane)sulfonimide (TFSI). Here we have performed a thorough exploration of this chemical treatment on CVD-grown MoS2 samples. We find that the as-grown monolayers must be transferred to a secondary substrate, which releases strain, to obtain high QY by TFSI treatment. Furthermore, we find that the sulfur precursor temperature during synthesis of the MoS2 plays a critical role in the effectiveness of the treatment. By satisfying the aforementioned conditions we show that the PL QY of CVD-grown monolayers can be improved from ∼0.1% in the as-grown case to ∼30% after treatment, with enhancement factors ranging from 100 to 1500× depending on the initial monolayer quality. We also found that after TFSI treatment the PL emission from MoS2 films was visible by eye despite the low absorption (5-10%). The discovery of an effective passivation strategy will speed the development of scalable high-performance optoelectronic and electronic devices based on MoS2. PMID:27291297

  17. Five new Zn(II) and Cd(II) coordination polymers constructed by 3,5-bis-oxyacetate-benzoic acid: Syntheses, crystal structures, network topologies and luminescent properties

    SciTech Connect

    Jiang Xianrong; Yuan Hongyan; Feng Yunlong

    2012-07-15

    Five Zn(II) and Cd(II) coordination polymers, [Zn{sub 2}(BOABA)(bpp)(OH)]{center_dot}0.5H{sub 2}O (1), [Cd{sub 3}(BOABA){sub 2}(bpp){sub 2}(H{sub 2}O){sub 6}]{center_dot}2H{sub 2}O (2), [Cd{sub 3}(BOABA){sub 2}(2,2 Prime -bipy){sub 3}(H{sub 2}O){sub 4}]{center_dot}5.5H{sub 2}O (3), [CdNa(BOABA)(H{sub 2}O)]{sub 2}{center_dot}H{sub 2}O (4) and [Cd{sub 2}(BOABA)(bimb)Cl(H{sub 2}O){sub 2}]{center_dot}H{sub 2}O (5) (H{sub 3}BOABA=3,5-bis-oxyacetate-benzoic acid, bpp=1,3-bi(4-pyridyl)propane, 2,2 Prime -bipy=2,2 Prime -bipyridine, bimb=1,4-bis(imidazol-1 Prime -yl)butane), have been solvothermally synthesized and characterized by single-crystal X-ray diffraction, elemental analyses, IR spectra and TG analyses. 1 is an uninodal 4-connected 2D square grid network based on binuclear zinc clusters. 2 is 2D wavelike layer structure and further linked by hydrogen bonds into the final 3D (5,6,6)-connected topology network. 3 is 3-connected 2D topology network and the 2,2 Prime -bipy ligands decorate in two different types. 4 is a (4,8)-connected 2D topology network with heterocaryotic {l_brace}Cd{sub 2}Na{sub 2}{r_brace} clusters and BOABA{sup 3-} ligands. 5 can be rationalized as a (3,10)-connected 3D topology network with tetranuclear {l_brace}Cd{sub 4}Cl{sub 2}{r_brace} clusters and BOABA{sup 3-} ligands. Meanwhile, photoluminescence studies revealed that these five coordination polymers display strong fluorescent emission bands in the solid state at room temperature. - Graphical abstract: Five new d{sup 10} metal(II) coordination polymers based on H{sub 3}BOABA ligand were obtained and characterized. They display different topological structures and luminescent properties. Highlights: Black-Right-Pointing-Pointer Five d{sup 10} metal(II) polymers based on 3,5-bis-oxyacetate-benzoic acid were obtained. Black-Right-Pointing-Pointer The polymers were structurally characterized by single-crystal X-ray diffraction. Black-Right-Pointing-Pointer Polymers 1-5 display different

  18. Luminescence studies using high-resolution intensified digital imaging: preliminary results

    NASA Astrophysics Data System (ADS)

    Castracane, James; Conerty, Michelle; Clow, Lawrence P.; Casscells, S. W.; Engler, David

    1997-06-01

    The use of bio-chemiluminescence immunoassay (BL/CLI) technology for molecular and cellular characterization is rapidly evolving. The excellent selectivity of this method can be exploited to identify the presence and distribution of specific cells. Current work involves the advancement of the required methods and technologies for application to the analysis of vascular wall surfaces. In this effort, various enzyme-linked antibodies are being explored which can be directed to cell surface antigens producing a luminogenic reaction. To aid in the analysis of this light emission, a custom high resolution digital imaging system which couples a multi-megapixel CCD with a specially designed image intensifier is under development. This intensifier system has high spatial resolution and excellent sensitivity in the wavelength region of the candidate BL/CL emissions. The application of this imaging system to BL/CLI requires unique performance characteristics and specialized optical design. Component level electro-optical tests of the imaging system will be presented along with design considerations for an eventual catheter based instrument. Initial in vitro experiments focused on the performance limits of the optical system in discriminating candidate luminogenic reactions. The main objective of these tests is the identification of suitable enzyme catalyzed systems for ultimate application to in vivo vascular tissue and cell diagnosis.

  19. Luminescent Nanofibers Fabricated from Phenanthroimidazole Derivatives by Organogelation: Fluorescence Response towards Acid with High Performance.

    PubMed

    Peng, Jiang; Sun, Jingbo; Gong, Peng; Xue, Pengchong; Zhang, Zhenqi; Zhang, Gonghe; Lu, Ran

    2015-08-01

    Nanofibers based on phenanthroimidazole derivatives PCC, PDC, and PSC were fabricated by organogelation processes, and their fluorescence sensory properties towards acid were investigated. It was found that the emission of PCC in the nanofiber-based film could be quenched significantly upon exposure to gaseous TFA due to the formation of protonated PCC, in which ICT (intramolecular charge transfer) would occur. On the other hand, TFA vapor led to the emitting colors of PDC and PSC in the nanofiber-based films to turn to yellow and green from sky blue and blue, respectively. Additionally, we found that the decay times of PCC were 0.1 s and 1.9 s in probing the saturated vapor of TFA in nanofiber-based film and in spin-coated film, respectively. The results suggested that the high surface-to-volume ratio and large interspace in the nanofiber-based networks favored the enhanced adsorption, accumulation, and diffusion of gaseous molecules, resulting in such a high performance. PMID:26034011

  20. Conducting polymers at low temperatures and high magnetic fields

    SciTech Connect

    Clark, J.C.; Ihas, G.G.; Reghu, M.

    1995-11-01

    Advances in the synthesis of organic conducting polymer systems has increased the electrical conductivity of these systems by several orders of magnitude in the last decade. Several practical applications are envisioned for such systems, but a thorough understanding of the conduction mechanisms and identification of the charge carriers is lacking, making design and implementation for bulk synthesis difficult. In order to clarify our understanding of the electrical properties of these systems, the resistivity and magnetoresistivity of various polymers doped near the metal - insulator transition, such as polyaniline protonated by camphor sulfonic acid (PANi-CSA) and polypyrrole doped with PF{sub 6} (PPy-PF{sub 6}), have been studied down to 25 mK in magnetic fields up to 16 T.

  1. Immunochromatographic assay for quantitative and sensitive detection of hepatitis B virus surface antigen using highly luminescent quantum dot-beads.

    PubMed

    Shen, Jun; Zhou, Yaofeng; Fu, Fen; Xu, Hengyi; Lv, Jiaofeng; Xiong, Yonghua; Wang, Andrew

    2015-09-01

    Hepatitis B virus infection is one of the major causes of hepatitis, liver cirrhosis and liver cancer. In this study, we used highly luminescent quantum dot-beads (QBs) as signal amplification probes in the sandwich immunochromatographic assay (ICA) for ultrasensitive and quantitative detection of hepatitis B virus surface antigen (HBsAg) in human serum. Various parameters that influenced the sensitivity and stability of the QB-based ICA (QB-ICA) sensor were investigated. Two linear independent regression equations for detection of serum HBsAg were expressed with Y=0.3361X-0.0059 (R(2)=0.9983) for low HBsAg concentrations between 75 pg mL(-1) and 4.8 ng mL(-1), and Y=0.8404 X-2.9364 (R(2)=0.9939) for high HBsAg concentrations in the range from 4.8 ng mL(-1) to 75 ng mL(-1). The detection limit of the proposed ICA sensor achieved was 75 pg mL(-1), which is much higher than that of the routinely-used gold nanoparticle based ICA. The intra- and inter-assays recovery rates for spiked serum samples at HBsAg concentrations of 75 pg mL(-1), 3.75 ng mL(-1) and 18.75 ng mL(-1) ranged from 90.14% to 97.6%, and coefficients of variation were all below 7%, indicating that the QB-ICA sensor has an acceptable accuracy for HBsAg detection. Additionally, the quantitative method developed showed no false positive results in an analysis of 49 real HBsAg-negative serum samples, and exhibited excellent agreement (R(2)=0.9209) with a commercial chemiluminescence immunoassay kit in identifying 47 HBsAg-positive serum samples. In summary, due to its high fluorescence intensity, the sandwich QB-ICA sensor is a very promising point-of-care test for rapid, simple and ultrasensitive detection of HBsAg, as well as other disease-related protein biomarkers. PMID:26003704

  2. Effect of High-Temperature Annealing on Yellow and Blue Luminescence of Undoped GaN

    NASA Astrophysics Data System (ADS)

    Chai, Xu-Zhao; Zhou, Dong; Liu, Bin; Xie, Zi-Li; Han, Ping; Xiu, Xiang-Qian; Chen, Peng; Lu, Hai; Zhang, Rong; Zheng, You-Dou

    2015-09-01

    Not Available Supported by the National Basic Research Program of China under Grant Nos 2011CB301900, 2012CB619200 and 2012CB619304, the High-Technology Research and Development Program of China under Grant Nos 2014AA032605 and 2015AA033305, the National Natural Science Foundation of China under Grant Nos 60990311, 61274003, 61422401, 51461135002, 60936004, 61176063 and 61334009, the Natural Science Foundation of Jiangsu Province under Grant Nos BK2011010 and BK20141320, the Scientific Innovation Research of College Graduate in Jiangsu Province under Grant No CXLX12_0049, a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions, and the Solid State Lighting and Energy-saving Electronics Collaborative Innovation Center.

  3. Fabrication of fluorescent composite with ultrafast aqueous synthesized high luminescent CdTe quantum dots

    NASA Astrophysics Data System (ADS)

    Zhang, Lei; Bi, Xianghong; Chen, Haibin; Wu, Jingshen

    2014-05-01

    Without precursor preparation, inert gas protection and enormous amount of additives and reductants, CdTe quantum dots (QDs) can be rapidly synthesized with high quality. A 600 nm photoluminescence peak wavelength could be obtained within 1 hour's refluxing through minimal addition of 1,2-diaminoethane (DAE). The theoretical design for the experiments are illustrated and further proved by the characterization results with different concentrations and reagents. On the other hand, generation of CdTe QDs was found even under room temperature by applying droplet quantity of DAE. This indicates that QDs can be synthesized with simply a bottle and no enormous additives required. The QDs were mixed into the epoxy matrix through solution casting method with cetyltrimethylammonium (CTA) capping for phase transfer. The acquired epoxy based nanocomposite exhibits good transparency, compatibility and fluorescence.

  4. Highly Luminescent Heterostructured Copper-Doped Zinc Sulfide Nanocrystals for Application in Cancer Cell Labeling.

    PubMed

    Ang, Huixiang; Bosman, Michel; Thamankar, Ramesh; Zulkifli, Muhammad Faizal B; Yen, Swee Kuan; Hariharan, Anushya; Sudhaharan, Thankiah; Selvan, Subramanian Tamil

    2016-08-18

    The structural characteristics of the seed-mediated synthesis of heterostructured CuS-ZnS nanocrystals (NCs) and Cu-doped ZnS (ZnS:Cu) NCs synthesized by two different protocols are compared and analyzed. At high Cu dopant concentrations, segregated subclusters of ZnS and CuS are observed. The photoluminescence quantum yield of ZnS:Cu NCs is about 50-80 %; a value much higher than that of ZnS NCs (6 %). Finally, these NCs are coated with a thin silica shell by using (3-mercaptopropyl)triethoxysilane in a reverse microemulsion to make them water soluble. Cytotoxicity experiments show that these silica-coated NCs have greatly reduced toxicity on both cancerous HeLa and noncancerous Chinese hamster ovary cells. The labeling of cancerous HeLa cells is also demonstrated. PMID:27146419

  5. Luminescence and Lasing in ZnSe Micropowders at High Optical Excitation Levels

    NASA Astrophysics Data System (ADS)

    Leanenya, M. S.; Lutsenko, E. V.; Pavlovskii, V. N.; Yablonskii, G. P.; Nagiev, T. G.; Tagiev, B. G.; Tagiev, O. B.; Abushev, S. A.

    2015-03-01

    Photoluminescence (PL) of ZnSe wide-bandgap semiconductor micropowder was studied at a high optical excitation level by pulsed nanosecond N2-laser emission. A new emission band that appeared on the long-wavelength edge of the PL spectrum at 40-75 meV from the electron-hole plasma (EHP) band depending on the optical excitation level showed that plasmons could participate in recombination processes in the EHP. Random lasing at 475 nm from submicron-sized crystallites in ZnSe powder was produced by the third harmonic of a YAG:Nd3+ laser with an exciting-radiation threshold intensity of 750 kW/cm2. The lasing manifested as a sharp increase of integrated emission intensity, a narrowing of the spectrum, and the appearance in it of localized and extended mode structure. Random lasing was due to feedback of amplified radiation in closely packed active scattering microcrystallites.

  6. Fabrication of fluorescent composite with ultrafast aqueous synthesized high luminescent CdTe quantum dots

    SciTech Connect

    Zhang, Lei Chen, Haibin E-mail: mejswu@ust.hk; Wu, Jingshen E-mail: mejswu@ust.hk; Bi, Xianghong

    2014-05-15

    Without precursor preparation, inert gas protection and enormous amount of additives and reductants, CdTe quantum dots (QDs) can be rapidly synthesized with high quality. A 600 nm photoluminescence peak wavelength could be obtained within 1 hour's refluxing through minimal addition of 1,2-diaminoethane (DAE). The theoretical design for the experiments are illustrated and further proved by the characterization results with different concentrations and reagents. On the other hand, generation of CdTe QDs was found even under room temperature by applying droplet quantity of DAE. This indicates that QDs can be synthesized with simply a bottle and no enormous additives required. The QDs were mixed into the epoxy matrix through solution casting method with cetyltrimethylammonium (CTA) capping for phase transfer. The acquired epoxy based nanocomposite exhibits good transparency, compatibility and fluorescence.

  7. Preparation of highly luminescent CdSe quantum dots by reverse micelles

    NASA Astrophysics Data System (ADS)

    Liu, Kang; Park, Sang Joon

    2014-08-01

    CdSe quantum dots (QDs) with relatively high photoluminescence (PL) quantum yield (QY) (about 30%) were prepared by a safe, low-cost, and simple synthesis method, utilizing a sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/water/cyclohexane microemulsion system. Cadmium chloride (CdCl2) and selenium powder were used as the cadmium and selenium sources, respectively. Size-tunable CdSe nanoparticles were obtained at various water-to-surfactant ratios, W ([H2O]/[surfactant]). The size of the CdSe nanoparticles increased, and the UV-vis absorption and PL peaks shifted towards the red region as W increased. Interestingly, the redshift also occurred when the ratio of Cd to Se increased. The highest PL efficiency was obtained at W of 5 and a Cd/Se ratio of 2:1. In addition, the CdSe nanoparticles with higher Cd to Se molar ratio (3/1) showed a higher stability against photooxidation.

  8. Novel cookie-with-chocolate carbon dots displaying extremely acidophilic high luminescence

    NASA Astrophysics Data System (ADS)

    Lu, Siyu; Zhao, Xiaohuan; Zhu, Shoujun; Song, Yubin; Yang, Bai

    2014-10-01

    A fluorescent carbon dot with a cookie-with-chocolate film structure (about 5 × 5 μm2) showed a high fluorescence quantum yield (61.12%) at low pH. It was hydrothermally synthesized from l-serine and l-tryptophan. The formation mechanism of the film with carbon dots (CDs) was investigated. The film structure was formed by hydrogen bonding and π-π stacking interactions between aromatic rings. The strong blue fluorescence of the CDs increased under strong acidic conditions owing to the changes in the N-groups. These cookie-like CDs are attractive for their potential use as effective fluorescent probes for the sensitive detection of aqueous H+ and Fe3+.A fluorescent carbon dot with a cookie-with-chocolate film structure (about 5 × 5 μm2) showed a high fluorescence quantum yield (61.12%) at low pH. It was hydrothermally synthesized from l-serine and l-tryptophan. The formation mechanism of the film with carbon dots (CDs) was investigated. The film structure was formed by hydrogen bonding and π-π stacking interactions between aromatic rings. The strong blue fluorescence of the CDs increased under strong acidic conditions owing to the changes in the N-groups. These cookie-like CDs are attractive for their potential use as effective fluorescent probes for the sensitive detection of aqueous H+ and Fe3+. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr03965c

  9. Luminescence study of homeopathic remedies

    NASA Astrophysics Data System (ADS)

    Lobyshev, Valentin I.; Tomkevitch, Marie

    2001-06-01

    It was shown in our recent papers that distilled water possesses intrinsic luminescence at wavelength of about 400 nm with excitation wavelength 300 nm, which is very sensitive to small amount of dissolved substances. This phenomena was chosen to study homeopathic remedies. Pronounced difference in the intensity of luminescence between several commercial preparations with the same potency and one preparation with various potencies was obtained. Long scale evolution of the spectra was registered and final result was dependent on preparation and its potency. Systematic study of homeopathic preparations of halit (natural sodium chloride) from 1 to 30 decimal dilution was done. A stepwise dilution with mechanical agitation between the dilution steps, the so-called potentisation, was produced specially by homeopathic company Weleda. Luminescence intensity against concentration (potency) of halit is non monotonous function with several maxima, the main maximum is located at 13-14-th dilution. Evolution of the spectra was registered during several months. The analogous potentisation treatment of water without additional substances results also in changes of the luminescence spectra, depending on the number of potentisation. The obtained differences of luminescence spectra at ultra high dilutions and potentisation show that the collective properties of water are really changed in homeopathic preparations.

  10. High electron mobility ZnO film for high-performance inverted polymer solar cells

    NASA Astrophysics Data System (ADS)

    Lv, Peiwen; Chen, Shan-Ci; Zheng, Qingdong; Huang, Feng; Ding, Kai

    2015-04-01

    High-quality ZnO films (ZnO-MS) are prepared via magnetron sputtering deposition with a high mobility of about 2 cm2/(V.s) and are used as electron transport layer for inverted polymer solar cells (PSCs) with polymer poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b']dithiophene-co-3-fluorothieno[3,4-b]thiophene-2-carboxylate]:[6,6]-phenyl C71-butyric acid methyl ester as the active layer. A significant improvement of JSC, about 20% enhancement in contrast to the devices built on sol-gel derived ZnO film (ZnO-Sol), is found in the ZnO-MS based device. High performance ZnO-MS based PSCs exhibit power conversion efficiency (PCE) up to 8.55%, which is much better than the device based on ZnO-Sol (PCE = 7.78%). Further research on cathode materials is promising to achieve higher performance.

  11. High electron mobility ZnO film for high-performance inverted polymer solar cells

    SciTech Connect

    Lv, Peiwen; Chen, Shan-Ci; Zheng, Qingdong; Huang, Feng Ding, Kai

    2015-04-20

    High-quality ZnO films (ZnO-MS) are prepared via magnetron sputtering deposition with a high mobility of about 2 cm{sup 2}/(V·s) and are used as electron transport layer for inverted polymer solar cells (PSCs) with polymer poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b′] dithiophene-co-3-fluorothieno[3,4-b]thiophene-2-carboxylate]:[6,6]-phenyl C71-butyric acid methyl ester as the active layer. A significant improvement of J{sub SC}, about 20% enhancement in contrast to the devices built on sol-gel derived ZnO film (ZnO-Sol), is found in the ZnO-MS based device. High performance ZnO-MS based PSCs exhibit power conversion efficiency (PCE) up to 8.55%, which is much better than the device based on ZnO-Sol (PCE = 7.78%). Further research on cathode materials is promising to achieve higher performance.

  12. Deep, high contrast microscopic cell imaging using three-photon luminescence of β-(NaYF4:Er3+/NaYF4) nanoprobe excited by 1480-nm CW laser of only 1.5-mW

    PubMed Central

    Liu, Jing; Wu, Ruitao; Li, Nana; Zhang, Xin; Zhan, Qiuqiang; He, Sailing

    2015-01-01

    It is challenging to achieve deep microscopic imaging for the strong scattering in biotissue. An efficient three-photon luminescence can effectively increase the penetration depth. Here we report that β-NaYF4: Er3+/NaYF4 UCNPs were excited by a 1480-nm CW-laser and emitted 543/653-nm light through a three-photon process. With the merit of the hexagonal crystal phase, sub-milliwatt laser power was utilized to excite the UCNP-probed cells to minimize the heating effect. The polymer-coated UCNPs were shown to be harmless to cells. The deep, high contrast in vitro microscopic imaging was implemented through an artificial phantom. Imaging depth of 800 μm was achieved using only 1.5 mW excitation and a 0.7 NA objective. The green/red emission intensities ratio after penetrating the phantom was studied, indicating that longer emission wavelength is preferred for deep multiphoton microscopy. The proposed and demonstrated β-UCNPs would have great potential in three-photon microscopy. PMID:26137385

  13. Deep, high contrast microscopic cell imaging using three-photon luminescence of β-(NaYF4:Er(3+)/NaYF4) nanoprobe excited by 1480-nm CW laser of only 1.5-mW.

    PubMed

    Liu, Jing; Wu, Ruitao; Li, Nana; Zhang, Xin; Zhan, Qiuqiang; He, Sailing

    2015-05-01

    It is challenging to achieve deep microscopic imaging for the strong scattering in biotissue. An efficient three-photon luminescence can effectively increase the penetration depth. Here we report that β-NaYF4: Er(3+)/NaYF4 UCNPs were excited by a 1480-nm CW-laser and emitted 543/653-nm light through a three-photon process. With the merit of the hexagonal crystal phase, sub-milliwatt laser power was utilized to excite the UCNP-probed cells to minimize the heating effect. The polymer-coated UCNPs were shown to be harmless to cells. The deep, high contrast in vitro microscopic imaging was implemented through an artificial phantom. Imaging depth of 800 μm was achieved using only 1.5 mW excitation and a 0.7 NA objective. The green/red emission intensities ratio after penetrating the phantom was studied, indicating that longer emission wavelength is preferred for deep multiphoton microscopy. The proposed and demonstrated β-UCNPs would have great potential in three-photon microscopy. PMID:26137385

  14. In vivo measurements for high dose rate brachytherapy with optically stimulated luminescent dosimeters

    SciTech Connect

    Sharma, Renu; Jursinic, Paul A.

    2013-07-15

    Purpose: To show the feasibility of clinical implementation of OSLDs for high dose-rate (HDR) in vivo dosimetry for gynecological and breast patients. To discuss how the OSLDs were characterized for an Ir-192 source, taking into account low gamma energy and high dose gradients. To describe differences caused by the dose calculation formalism of treatment planning systems.Methods: OSLD irradiations were made using the GammaMedplus iX Ir-192 HDR, Varian Medical Systems, Milpitas, CA. BrachyVision versions 8.9 and 10.0, Varian Medical Systems, Milpitas, CA, were used for calculations. Version 8.9 used the TG-43 algorithm and version 10.0 used the Acuros algorithm. The OSLDs (InLight Nanodots) were characterized for Ir-192. Various phantoms were created to assess calculated and measured doses and the angular dependence and self-absorption of the Nanodots. Following successful phantom measurements, patient measurements for gynecological patients and breast cancer patients were made and compared to calculated doses.Results: The OSLD sensitivity to Ir-192 compared to 6 MV is between 1.10 and 1.25, is unique to each detector, and changes with accumulated dose. The measured doses were compared to those predicted by the treatment planning system and found to be in agreement for the gynecological patients to within measurement uncertainty. The range of differences between the measured and Acuros calculated doses was -10%-14%. For the breast patients, there was a discrepancy of -4.4% to +6.5% between the measured and calculated doses at the skin surface when the Acuros algorithm was used. These differences were within experimental uncertainty due to (random) error in the location of the detector with respect to the treatment catheter.Conclusions: OSLDs can be successfully used for HDR in vivo dosimetry. However, for the measurements to be meaningful one must account for the angular dependence, volume-averaging, and the greater sensitivity to Ir-192 gamma rays than to 6 MV x

  15. Carrier-free, water dispersible and highly luminescent dye nanoparticles for targeted cell imaging

    NASA Astrophysics Data System (ADS)

    Diao, Xiaojun; Li, Wei; Yu, Jia; Wang, Xiaojing; Zhang, Xiujuan; Yang, Yinlong; An, Feifei; Liu, Zhuang; Zhang, Xiaohong

    2012-08-01

    We develop a new strategy of using surface functionalized small molecule organic dye nanoparticles (NPs) for targeted cell imaging. Organic dye (2-tert-butyl-9,10-di(naphthalen-2-yl)anthracene, TBADN) was fabricated into NPs and this was followed by surface modification with an amphipathic surfactant poly(maleic anhydride-alt-1-octadecene)-polyethylene glycol (C18PMH-PEG) through hydrophobic interactions to achieve good water dispersibility and bio-environmental stability. It should be noted that no additional inert materials were added as carriers, thus the dye-loading capacity of the resulting TBADN NPs is obviously higher than those of previously reported carrier-based structures. This would lead to much larger absorption and then much higher brightness. The resulting TBADN NPs possess comparable, if not higher, brightness than CdSe/ZnS quantum dots under the same conditions, with favorable biocompatibility. Significantly, TBADN NPs are readily conjugated with folic acid, and successfully applied in targeted cell imaging. These results show that water dispersible and highly stable organic NPs would be a promising new class of fluorescent probe for bioapplications in cellular imaging and labeling. This strategy may be straightforwardly extended to other organic dyes to achieve water dispersible NPs for cell imaging and drug delivery.We develop a new strategy of using surface functionalized small molecule organic dye nanoparticles (NPs) for targeted cell imaging. Organic dye (2-tert-butyl-9,10-di(naphthalen-2-yl)anthracene, TBADN) was fabricated into NPs and this was followed by surface modification with an amphipathic surfactant poly(maleic anhydride-alt-1-octadecene)-polyethylene glycol (C18PMH-PEG) through hydrophobic interactions to achieve good water dispersibility and bio-environmental stability. It should be noted that no additional inert materials were added as carriers, thus the dye-loading capacity of the resulting TBADN NPs is obviously higher than

  16. Macroporous Polymers with Aligned Microporous Walls from Pickering High Internal Phase Emulsions.

    PubMed

    Zhu, Yun; Zhang, Ranran; Zhang, Shengmiao; Chu, Yeqian; Chen, Jianding

    2016-06-21

    A novel class of macroporous polymers, open macroporous polymers with aligned microporous void walls, were prepared by combining particle-stabilized high internal phase emulsion (Pickering HIPE) and unidirectional freezing technique. These Pickering HIPEs were prepared by utilizing poly(urethane urea)/(vinyl ester resin) nanoparticles as the sole stabilizer, and this nanoparticles also acted as building blocks for the resulting macroporous polymers. Moreover, the morphology and compression modulus of the resulting porous materials could be tuned easily. This means now Pickering-HIPE templated open-cell foams can be prepared, and this route was normally achieved with surfactant and/or chemical reaction involved. PMID:27249538

  17. Assembly of a Highly Stable Luminescent Zn5 Cluster and Application to Bio-Imaging.

    PubMed

    Zeng, Ming-Hua; Yin, Zheng; Liu, Ze-Hui; Xu, Hai-Bing; Feng, Ying-Chun; Hu, Yue-Qiao; Chang, Li-Xian; Zhang, Yue-Xing; Huang, Jin; Kurmoo, Mohamedally

    2016-09-12

    The assembly sequence of the coordination cluster [Zn5 (H2 L(n) )6 ](NO3 )4 ]⋅8 H2 O⋅2 CH3 OH (Zn5 , H3 L(n) =(1,2-bis(benzo[d]imidazol-2-yl)-ethenol) involves in situ dehydration of 1,2-bis(benzo[d]imidazol-2-yl)-1,2-ethanediol (H4 L) through the formation of the [Zn(H3 L)2 ](+) monomer, dimerization to [Zn2 (H3 L)2 ](+) , dehydration of the ligand to [Zn2 (H2 L(n) )2 ](+) , and the final formation of the pentanuclear cluster. The cluster has the following special characteristics: 1) high stability in both refluxing 37 % HCl and 27 % NH3 , 2) low cytotoxicity, and 3) pH-sensitive fluorescence in the visible-to-near-infrared (Vis/NIR) region in the solid state and in solution. We have applied it as a fluorescent probe both in vivo and in vitro. Its H-bonding ability is the key to its affinity and selectivity for imaging lysosomes in HeLa cells and tumors in male BALB/C mice. It provides a new type of sensitive and biocompatible fluorescent probe for detecting small tumors (13.5 mm(3) ). PMID:27529333

  18. Luminescent tracks of high-energy photoemitted electrons accelerated by plasmonic fields

    NASA Astrophysics Data System (ADS)

    Di Vece, Marcel; Giannakoudakis, Giorgos; Bjørkøy, Astrid; Tang, Wingjohn

    2015-12-01

    The emission of an electron from a metal nanostructure under illumination and its subsequent acceleration in a plasmonic field forms a platform to extend these phenomena to deposited nanoparticles, which can be studied by state-of-the-art confocal microscopy combined with femtosecond optical excitation. The emitted and accelerated electrons leave defect tracks in the immersion oil, which can be revealed by thermoluminescence. These photographic tracks are read out with the confocal microscope and have a maximum length of about 80 μm, which corresponds to a kinetic energy of about 100 keV. This energy is consistent with the energy provided by the intense laser pulse combined with plasmonic local field enhancement. The results are discussed within the context of the rescattering model by which electrons acquire more energy. The visualization of electron tracks originating from plasmonic field enhancement around a gold nanoparticle opens a new way to study with confocal microscopy both the plasmonic properties of metal nano objects as well as high energy electron interaction with matter.

  19. High pressure study of viscosity effects on the luminescence of tetracyanobenzene EDA complexes

    NASA Astrophysics Data System (ADS)

    Thomas, Michele Moisio; Drickamer, H. G.

    1981-03-01

    High pressure fluorescence studies fron 0-10 kbar have been performed on electron donor-acceptor (EDA) complexes of s-tetracyanobenzene (TCNB) with a series of aromatic hydrocarbons. Four solvents were used, 2,2,4,4,6,8,8 heptamethylnonane (HMN), methylcyclohexane (MCH), 2,6,10,14 tetramethylpentadecane (TMPD), and a mixture of MCH and HMN. A viscosity range from 0.006 to 10 000 poise was covered at constant temperature. As pressure (viscosity) increased the fluorescence spectrum shifted from one dominated by emission from the equilibrium (EQ) excited singlet state to one dominated by Franck-Condon (FC) singlet emission. Lifetime measurements for the complexes of o-xylene and p-xylene with TCNB as well as one mesitylene complex yielded the two radiative rates (kEQ and kFC) as well as the rate of internal conversion from FC to the EQ excited state to (kIC). The results are discussed in terms of the rate of relaxation of the solvent compared with the rate kFC. It was found that kIC correlated very well with the solvent viscosity.

  20. Optical, luminescent and laser properties of highly transparent ytterbium doped yttrium lanthanum oxide ceramics

    NASA Astrophysics Data System (ADS)

    Ivanov, M.; Kopylov, Yu.; Kravchenko, V.; Li, Jiang; Pan, Yubai; Kynast, U.; Leznina, M.; Strek, W.; Marciniak, Lukasz; Palashov, O.; Snetkov, I.; Mukhin, I.; Spassky, D.

    2015-12-01

    This paper describes the fabrication and investigation of highly transparent Yb-doped yttrium lanthanum oxide ceramics. For sintering of the ceramics we used a technology, which consists of several consecutive steps: (a) synthesis of weakly agglomerated nanopowder by laser ablation, (b) compacting of the green body with cold isostatic pressing (CIP), and (c) sintering in vacuum. After calcinations of the synthesized nanopowder at 1200 °C, a pure single-phase solid solution Yb3+:(LaxY1-x)2O3 was formed. The lanthanum ions proved to be a good aid to sinter yttria ceramics doped with Yb3+ at comparatively moderate temperatures of about 1650 °C. The ceramics have a relative density higher than 99.99% and grain sizes around 40 μm. The absorption coefficient of 3.2 mm thick Yb0.12La0.27Y1.61O3 ceramics is 0.01 cm-1 at 1150 nm. Laser oscillation at a wavelength of 1033 nm is demonstrated.

  1. Impact of ligand framework on the crystal structures and luminescent properties of Cu(I) and Ag(I) clusters and a coordination polymer derived from thiolate/iodide/dppm ligands.

    PubMed

    Rajput, Gunjan; Yadav, Manoj Kumar; Drew, Michael G B; Singh, Nanhai

    2015-03-16

    New homoleptic hexanuclear Ag(I) and heteroleptic trinuclear Cu(I) clusters and a Cu(I) coordination polymer (CP) of the formulas [Ag6(dtc)6] 1, [Cu3I2(dppm)3(dtc)] 2, and [Cu(ttc)I]∞ 3 (dtc = N-methylbenzyl-N-methyl-thiophenedithiocarbamate; dppm = 1,1-bis(diphenylphosphino)methane; and ttc = dimethyltrithiocarbonate) were synthesized and characterized by elemental analysis, IR, UV-vis, (1)H, (13)C, and (31)P NMR spectroscopies, and their structures were elucidated by X-ray crystallography. The complexes show interesting structures and luminescent properties. Complex 1, which is centrosymmetric, contains four short Ag···Ag interactions at 2 × 2.966(1) and 2 × 3.014(1) Å. There are also several Ag···Ag distances of 3.3-3.4 Å. The molecule shows hexagonal orientation with alternating silver and sulfur atoms of the overlapping Ag3S3 hexagons in the front and rear, along the a axis. Complex 2 is a rare trinuclear cluster complex of Cu(I); the Cu···Cu distances are 2.906(2), 3.551(2), and 3.338(2) Å, the foremost representing a substantial intermetallic contact. The Cu3I2P6S2 core is comprised of three fused distorted hexagonal rings with the I1 atom located at the center participating in all three rings. Complex 3 is an iodide-bridged CP with a "staircase"-like arrangement in which the Cu(I) is tetrahedrally surrounded by a sulfur atom from the ttc ligand and three iodine atoms. Unlike 3, which is nonluminescent, 1 and 2 are strongly luminescent in the solid and solution at room temperature. The time-resolved emission spectra reveal a triexponential decay curve and short mean lifetime characteristic of fluorescence behavior. Diffuse reflectance spectroscopy revealed semiconducting behavior with band gaps of 2.12, 3.01, and 2.18 eV for 1-3, respectively. PMID:25699659

  2. High performance all polymer solar cells fabricated via non-halogenated solvents (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Zhou, Yan; Bao, Zhenan

    2015-10-01

    The performance of organic solar cells consisting of a donor/acceptor bulk heterojunction (BHJ) has rapidly improved over the past few years.1. Major efforts have been focused on developing a variety of donor materials to gain access to different regions of the solar spectrum as well as to improve carrier transport properties.2 On the other hand, the most utilized acceptors are still restricted to the fullerene family, which includes PC61BM, PC71BM and ICBA.2b, 3 All-polymer solar cells, consisting of polymers for both the donor and acceptor, gained significantly increased interests recently, because of their ease of solution processing, potentially low cost, versatility in molecular design, and their potential for good chemical and morphological stability due to entanglement of polymers. Unlike small molecular fullerene acceptors, polymer acceptors can benefit from the high mobility of intra-chain charge transport and exciton generation by both donor and acceptor. Despite extensive efforts on all-polymer solar cells in the past decade, the fundamental understanding of all-polymer solar cells is still in its inceptive stage regarding both the materials chemistry and structure physics.4 Thus, rational design rules must be utilized to enable fundamental materials understanding of the all polymer solar cells. We report high performance all-polymer solar cells employing polymeric donors based on isoindigo and acceptor based on perylenedicarboximide. The phase separation domain length scale correlates well with the JSC and is found to be highly sensitive to the aromatic co-monomer structures used in the crystalline donor polymers. With the PS polymer side chain engineering, the phase separation domain length scale decreased by more than 45%. The PCE and JSC of the devices increased accordingly by more than 20%. A JSC as high as 10.0 mA cm-2 is obtained with the donor-acceptor pair despite of a low LUMO-LUMO energy offset of less than 0.1 eV. All the factors such as

  3. High-efficiency polymer solar cells with small photon energy loss

    PubMed Central

    Kawashima, Kazuaki; Tamai, Yasunari; Ohkita, Hideo; Osaka, Itaru; Takimiya, Kazuo

    2015-01-01

    A crucial issue facing polymer-based solar cells is how to manage the energetics of the polymer/fullerene blends to maximize short-circuit current density and open-circuit voltage at the same time and thus the power conversion efficiency. Here we demonstrate that the use of a naphthobisoxadiazole-based polymer with a narrow bandgap of 1.52 eV leads to high open-circuit voltages of approximately 1 V and high-power conversion efficiencies of ∼9% in solar cells, resulting in photon energy loss as small as ∼0.5 eV, which is much smaller than that of typical polymer systems (0.7–1.0 eV). This is ascribed to the high external quantum efficiency for the systems with a very small energy offset for charge separation. These unconventional features of the present polymer system will inspire the field of polymer-based solar cells towards further improvement of power conversion efficiencies with both high short-circuit current density and open-circuit voltage. PMID:26626042

  4. High-efficiency polymer solar cells with small photon energy loss

    NASA Astrophysics Data System (ADS)

    Kawashima, Kazuaki; Tamai, Yasunari; Ohkita, Hideo; Osaka, Itaru; Takimiya, Kazuo

    2015-12-01

    A crucial issue facing polymer-based solar cells is how to manage the energetics of the polymer/fullerene blends to maximize short-circuit current density and open-circuit voltage at the same time and thus the power conversion efficiency. Here we demonstrate that the use of a naphthobisoxadiazole-based polymer with a narrow bandgap of 1.52 eV leads to high open-circuit voltages of approximately 1 V and high-power conversion efficiencies of ~9% in solar cells, resulting in photon energy loss as small as ~0.5 eV, which is much smaller than that of typical polymer systems (0.7-1.0 eV). This is ascribed to the high external quantum efficiency for the systems with a very small energy offset for charge separation. These unconventional features of the present polymer system will inspire the field of polymer-based solar cells towards further improvement of power conversion efficiencies with both high short-circuit current density and open-circuit voltage.

  5. High-efficiency polymer solar cells with small photon energy loss.

    PubMed

    Kawashima, Kazuaki; Tamai, Yasunari; Ohkita, Hideo; Osaka, Itaru; Takimiya, Kazuo

    2015-01-01

    A crucial issue facing polymer-based solar cells is how to manage the energetics of the polymer/fullerene blends to maximize short-circuit current density and open-circuit voltage at the same time and thus the power conversion efficiency. Here we demonstrate that the use of a naphthobisoxadiazole-based polymer with a narrow bandgap of 1.52 eV leads to high open-circuit voltages of approximately 1 V and high-power conversion efficiencies of ∼9% in solar cells, resulting in photon energy loss as small as ∼0.5 eV, which is much smaller than that of typical polymer systems (0.7-1.0 eV). This is ascribed to the high external quantum efficiency for the systems with a very small energy offset for charge separation. These unconventional features of the present polymer system will inspire the field of polymer-based solar cells towards further improvement of power conversion efficiencies with both high short-circuit current density and open-circuit voltage. PMID:26626042

  6. Nanoparticle-assisted high photoconductive gain in polymer/fullerene matrix

    PubMed Central

    Chen, Hsiang-Yu; Lo, Michael K. F.; Yang, Guanwen; Monbouquette, Harold G.; Yang, Yang

    2014-01-01

    Polymer/inorganic nanocrystal composites1–10 offer an attractive means to combine the merits of organic and inorganic materials into novel electronic and photonic systems. However, many applications of these composites are limited by the solubility11 and distribution of nanocrystals (NCs) in polymer matrices. Here, a high photoconductive gain has been achieved by blending cadmium telluride (CdTe) nanoparticles (NPs) into a polymer/fullerene matrix followed by a solvent annealing12 process. The NP surface capping ligand, N-phenyl-N’-methyldithiocarbamate, renders the NPs highly soluble in the polymer blend thereby enabling high nanocrystal loadings. An external quantum efficiency (EQE) as high as ~8000% (at 350nm) is reached at −4.5V. Hole-dominant devices coupled with AFM images are studied to uncover the probable mechanism. We observe a higher concentration of CdTe NPs is located near the cathode/polymer interface. These NPs with trapped electrons assist hole injection into the polymer under reverse bias, which contributes to greater than 100% EQE. PMID:18772915

  7. Design of semiconducting indacenodithiophene polymers for high performance transistors and solar cells.

    PubMed

    McCulloch, Iain; Ashraf, Raja Shahid; Biniek, Laure; Bronstein, Hugo; Combe, Craig; Donaghey, Jenny E; James, David I; Nielsen, Christian B; Schroeder, Bob C; Zhang, Weimin

    2012-05-15

    The prospect of using low cost, high throughput material deposition processes to fabricate organic circuitry and solar cells continues to drive research towards improving the performance of the semiconducting materials utilized in these devices. Conjugated aromatic polymers have emerged as a leading candidate semiconductor material class, due to their combination of their amenability to processing and reasonable electrical and optical performance. Challenges remain, however, to further improve the charge carrier mobility of the polymers for transistor applications and the power conversion efficiency for solar cells. This optimization requires a clear understanding of the relationship between molecular structure and both electronic properties and thin film morphology. In this Account, we describe an optimization process for a series of semiconducting polymers based on an electron rich indacenodithiophene aromatic backbone skeleton. We demonstrate the effect of bridging atoms, alkyl chain functionalization, and co-repeating units on the morphology, molecular orbital energy levels, charge carrier mobility, and solar cell efficiencies. This conjugated unit is extremely versatile with a coplanar aromatic ring structure, and the electron density can be manipulated by the choice of bridging group between the rings. The functionality of the bridging group also plays an important role in the polymer solubility, and out of plane aliphatic chains present in both the carbon and silicon bridge promote solubility. This particular polymer conformation, however, typically suppresses long range organization and crystallinity, which had been shown to strongly influence charge transport. In many cases, polymers exhibited both high solubility and excellent charge transport properties, even where there was no observable evidence of polymer crystallinity. The optical bandgap of the polymers can be tuned by the combination of the donating power of the bridging unit and the electron

  8. High-order sampling schemes for path integrals and Gaussian chain simulations of polymers

    SciTech Connect

    Müser, Martin H.; Müller, Marcus

    2015-05-07

    In this work, we demonstrate that path-integral schemes, derived in the context of many-body quantum systems, benefit the simulation of Gaussian chains representing polymers. Specifically, we show how to decrease discretization corrections with little extra computation from the usual O(1/P{sup 2}) to O(1/P{sup 4}), where P is the number of beads representing the chains. As a consequence, high-order integrators necessitate much smaller P than those commonly used. Particular emphasis is placed on the questions of how to maintain this rate of convergence for open polymers and for polymers confined by a hard wall as well as how to ensure efficient sampling. The advantages of the high-order sampling schemes are illustrated by studying the surface tension of a polymer melt and the interface tension in a binary homopolymers blend.

  9. Interconnected Porous Polymers with Tunable Pore Throat Size Prepared via Pickering High Internal Phase Emulsions.

    PubMed

    Xu, Hongyun; Zheng, Xianhua; Huang, Yifei; Wang, Haitao; Du, Qiangguo

    2016-01-12

    Interconnected macroporous polymers were prepared by copolymerizing methyl acrylate (MA) via Pickering high internal phase emulsion (HIPE) templates with modified silica particles. The pore structure of the obtained polymer foams was observed by field-emission scanning electron microscopy (FE-SEM). Gas permeability was characterized to evaluate the interconnectivity of macroporous polymers. The polymerization shrinkage of continuous phase tends to form open pores while the solid particles surrounding the droplets act as barriers to produce closed pores. These two conflicting factors are crucial in determining the interconnectivity of macroporous polymers. Thus, poly-Pickering HIPEs with high permeability and well-defined pore structure can be achieved by tuning the MA content, the internal phase fraction, and the content of modified silica particles. PMID:26673546

  10. Titanium compounds as catalysts of higher alpha-olefin-based super-high-molecular polymers synthesis

    NASA Astrophysics Data System (ADS)

    Konovalov, K. B.; Kazaryan, M. A.; Manzhay, V. N.; Vetrova, O. V.

    2016-01-01

    The synthesis of polymers of 10 million or more molecular weight is a difficult task even in a chemical lab. Higher α-olefin-based polymer agents of such kind have found a narrow but quite important niche, the reduction of drag in the turbulent flow of hydrocarbon fluids such as oil and oil-products. In its turn, searching for a catalytic system capable to produce molecules of such a high length and to synthesize polymers of a low molecular-mass distribution is part of a global task of obtaining a high-quality product. In this paper we had observed a number of industrial catalysts with respect to their suitability for higher poly-α- olefins synthesis. A number samples representing copolymers of 1-hexene with 1-decene obtained on a previous generation catalyst, a microsphere titanium chloride catalytic agent had been compared to samples synthesized using a titanium-magnesium catalyst both in solution and in a polymer medium.

  11. A luminescent nanocrystal stress gauge

    SciTech Connect

    Choi, Charina; Koski, Kristie; Olson, Andrew; Alivisatos, Paul

    2010-10-25

    Microscale mechanical forces can determine important outcomes ranging from the site of material fracture to stem cell fate. However, local stresses in a vast majority of systems cannot be measured due to the limitations of current techniques. In this work, we present the design and implementation of the CdSe/CdS core/shell tetrapod nanocrystal, a local stress sensor with bright luminescence readout. We calibrate the tetrapod luminescence response to stress, and use the luminescence signal to report the spatial distribution of local stresses in single polyester fibers under uniaxial strain. The bright stress-dependent emission of the tetrapod, its nanoscale size, and its colloidal nature provide a unique tool that may be incorporated into a variety of micromechanical systems including materials and biological samples to quantify local stresses with high spatial resolution.

  12. Mercury coordination polymers with flexible ethane-1,2-diyl-bis-(pyridyl-3-carboxylate): Synthesis, structures, thermal and luminescent properties

    SciTech Connect

    Vallejos, Javier; Brito, Iván; Cárdenas, Alejandro; Llanos, Jaime; Bolte, Michael; López-Rodríguez, Matías

    2015-03-15

    The reaction of the flexible ligand, ethane-1,2-diyl-bis-(pyridyl-3-carboxylate), (L) with HgI{sub 2} and HgBr{sub 2} salts under the same experimental conditions leads to the formation of two coordination polymers with different motifs: ([Hg(L)(Br{sub 2})]){sub n}(1) and ([Hg(L)(I{sub 2})]){sub n}(2). In both compounds, the ligand, (L) acts in a μ2-N:N′-bidentate fashion to link HgBr{sub 2} and HgI{sub 2} units to form a linear and helical chain motif, along [1 0 0] for (1) and [0 0 1] for (2). The ethylene moiety of (L) has gauche and trans conformation in compounds (1) and (2), respectively. The flexible conformation of L produces differences in the optical and crystal properties of the two compounds. - Graphical abstract: This work demonstrates how the HgX{sub 2} units are coordinates by bi-dentate ligand forming polymeric coordination complexes by self-assembly of both chemical units.- Highlights: • News 1-D d{sup 10} transition metal coordination polymers. • The photoluminescent properties have been measured. • The thermal properties have been measured.

  13. Luminescence of thin-film light-emitting diode structures upon excitation by a high-current electron beam

    NASA Astrophysics Data System (ADS)

    Oleshko, V. I.; Gorina, S. G.; Korepanov, V. I.; Lisitsyn, V. M.; Prudaev, I. A.; Tolbanov, O. P.

    2013-06-01

    The possibility is examined of applying strong electron beams for luminescence control of InGaN/GaN lightemitting-diode heterostructures deposited on a sapphire substrate. It is shown that excitation of the samples by an electron beam from the heterostructure side leads to intense luminescence of the GaN and InGaN epitaxial layers, whose characteristics are determined by the prehistory of the samples. Induced emission is detected, arising in separate light-emitting-diode structures when the energy density of the electron beam reaches a threshold value. Transition to the induced emission regime in InGaN quantum wells is accompanied by the appearance of a luminous halo around the excitation zone.

  14. Simple fiber optic coupled luminescence cryostat

    NASA Astrophysics Data System (ADS)

    Meyer, G. D.; Ortiz, T. P.; Costello, A. L.; Brozik, J. A.; Kenney, J. W.

    2002-12-01

    An easy to fabricate, easy to operate, miniature liquid helium insert cryostat has been designed for variable low-temperature luminescence investigations in the 2.7-77 K region with minimal liquid helium consumption. The cryostat, which can be used inside of a standard liquid helium storage Dewar, is optically coupled both to the luminescence spectrophotometer and to the chosen luminescence excitation source (laser or conventional) by a single 1 mm fused silica fiber optic cable. This extremely simple and compact optical system is designed to give highly reproducible luminescence excitation and collection efficiencies for quantitative luminescence intensity studies. Temperature control in the cryostat is achieved through the dynamic balance of up to three distinct heating/cooling processes: raising or lowering the cryostat with respect to the liquid helium level in the Dewar, heating the cryostat with a small resistance heater, or pumping on the cryostat for sub-4.2 K temperatures. The cryostat can operate effectively throughout the 2.7-77 K range in liquid helium storage Dewars containing less than a liter of liquid helium. The wide range of spectroscopic experiments that this novel optical cryostat design can support is illustrated by a temperature-dependent zero field splitting luminescence lifetime study of Ru(bpy)3Cl2, a temperature-dependent relative luminescence intensity (quantum yield) study of Ru(bpy)3Cl2, and a temperature-dependent luminescence vibronic fine structure study of Ti(Cp)2(NCS)2.

  15. Tunable Luminescence of Silicon Nanoparticles

    NASA Astrophysics Data System (ADS)

    Vladimirov, A.; Korovin, S.; Surkov, A.; Kelm, E.; Pustovoy, V.

    2010-10-01

    The luminescent properties of silicon nanoparticles were studied. The particles were prepared by laser pyrolysis of silane in a gas flow reactor. Initially non-luminescent particles were treated by the chemical etching in mixture of fluoric and nitric acids. The high and stable photoluminescence from etched particles was observed. With increasing etching time, the PL peak shifted to blue region. With decreasing of the excitation wavelength from 660 nm to 365 nm, the PL peak shifted from 820 nm to 660 nm. This allows us to use the silicon based particles for wavelength selected excitation in some practical application.

  16. Protective Polymer Coatings for High-Throughput, High-Purity Cellular Isolation

    PubMed Central

    2016-01-01

    Cell-based therapies are emerging as the next frontier of medicine, offering a plausible path forward in the treatment of many devastating diseases. Critically, current methods for antigen positive cell sorting lack a high throughput method for delivering ultrahigh purity populations, prohibiting the application of some cell-based therapies to widespread diseases. Here we show the first use of targeted, protective polymer coatings on cells for the high speed enrichment of cells. Individual, antigen-positive cells are coated with a biocompatible hydrogel which protects the cells from a surfactant solution, while uncoated cells are immediately lysed. After lysis, the polymer coating is removed through orthogonal photochemistry, and the isolate has >50% yield of viable cells and these cells proliferate at rates comparable to control cells. Minority cell populations are enriched from erythrocyte-depleted blood to >99% purity, whereas the entire batch process requires 1 h and <$2000 in equipment. Batch scale-up is only contingent on irradiation area for the coating photopolymerization, as surfactant-based lysis can be easily achieved on any scale. PMID:26244409

  17. Flexible High-Energy Polymer-Electrolyte-Based Rechargeable Zinc-Air Batteries.

    PubMed

    Fu, Jing; Lee, Dong Un; Hassan, Fathy Mohamed; Yang, Lin; Bai, Zhengyu; Park, Moon Gyu; Chen, Zhongwei

    2015-10-01

    A thin-film, flexible, and rechargeable zinc-air battery having high energy density is reported particularly for emerging portable and wearable electronic applications. This freeform battery design is the first demonstrated by sandwiching a porous-gelled polymer electrolyte with a freestanding zinc film and a bifunctional catalytic electrode film. The flexibility of both the electrode films and polymer electrolyte membrane gives great freedom in tailoring the battery geometry and performance. PMID:26305154

  18. High sensitivity quadrupole mass spectrometry of neutrals sputtered by UV-laser ablation of polymers

    NASA Astrophysics Data System (ADS)

    Lazare, Sylvain; Guan, Weiping; Drilhole, David

    1996-04-01

    Laser Ablation-Sputtered Neutrals Spectrometry is developed as a portable system which consists of a commercial gas analyser (quadrupole mass spectrometer with e-beam ionization) in ultrahigh vacuum. ArF and KrF ablation of 20 polymers yielded mass spectra (1-200), rich in information, and mass intensity versus etching time for depth profiling analysis. The sensitivity is very high (100 ng of polymer can be probed) and microablation can be recorded by LA-SNMS.

  19. High interfacial activity of polymers "grafted through" functionalized iron oxide nanoparticle clusters.

    PubMed

    Foster, Lynn M; Worthen, Andrew J; Foster, Edward L; Dong, Jiannan; Roach, Clarissa M; Metaxas, Athena E; Hardy, Clifford D; Larsen, Eric S; Bollinger, Jonathan A; Truskett, Thomas M; Bielawski, Christopher W; Johnston, Keith P

    2014-09-01

    The mechanism by which polymers, when grafted to inorganic nanoparticles, lower the interfacial tension at the oil-water interface is not well understood, despite the great interest in particle stabilized emulsions and foams. A simple and highly versatile free radical "grafting through" technique was used to bond high organic fractions (by weight) of poly(oligo(ethylene oxide) monomethyl ether methacrylate) onto iron oxide clusters, without the need for catalysts. In the resulting ∼1 μm hybrid particles, the inorganic cores and grafting architecture contribute to the high local concentration of grafted polymer chains to the dodecane/water interface to produce low interfacial tensions of only 0.003 w/v % (polymer and particle core). This "critical particle concentration" (CPC) for these hybrid inorganic/polymer amphiphilic particles to lower the interfacial tension by 36 mN/m was over 30-fold lower than the critical micelle concentration of the free polymer (without inorganic cores) to produce nearly the same interfacial tension. The low CPC is favored by the high adsorption energy (∼10(6) kBT) for the large ∼1 μm hybrid particles, the high local polymer concentration on the particles surfaces, and the ability of the deformable hybrid nanocluster cores as well as the polymer chains to conform to the interface. The nanocluster cores also increased the entanglement of the polymer chains in bulk DI water or synthetic seawater, producing a viscosity up to 35,000 cP at 0.01 s(-1), in contrast with only 600 cP for the free polymer. As a consequence of these interfacial and rheological properties, the hybrid particles stabilized oil-in-water emulsions at concentrations as low as 0.01 w/v %, with average drop sizes down to 30 μm. In contrast, the bulk viscosity was low for the free polymer, and it did not stabilize the emulsions. The ability to influence the interfacial activity and rheology of polymers upon grafting them to inorganic particles, including clusters

  20. Directed Self-assembly of Nanoparticles at the Polymer Surface by Highly Compressible Supercritical Carbon Dioxide

    SciTech Connect

    M Asada; P Gin; M Endoh; S Satija; T Taniguchi; T Koga

    2011-12-31

    We report a versatile route for self-assembly of polymer-soluble nanoparticles at the polymer surface using highly compressible supercritical carbon dioxide (scCO{sub 2}). Polystyrene and poly(methyl methacrylate)-based nanocomposite thin films with functionalized polyhedral oligomeric silsesquioxane and phenyl C{sub 61} butyric acid methyl ester nanoparticles were prepared on Si substrates and exposed to scCO{sub 2} at different pressures under the isothermal condition of 36 C. The resultant structures could be then preserved by the vitrification process of the glassy polymers via quick pressure quench to atmospheric pressure and subsequently characterized by using various surface sensitive experimental techniques in air. We found that the surface segregation of these nanoparticles is induced in the close vicinity of P = 8.2 MPa where the excess absorption of the fluid into the polymers maximizes. However, when the film thickness becomes less than about 4R{sub g} thick (where R{sub g} is the radius of polymer gyration), the uniform dispersion of the nanoparticles is favorable instead even at the same CO{sub 2} conditions. We clarify that the phase transition is correlated with the emergence of a concentration gradient of the fluid at the polymer/CO{sub 2} interface and is a general phenomenon for different polymer-nanoparticle interactions.

  1. Comparison of retrospective luminescence dosimetry with computational modeling in two highly contaminated settlements downwind of the Chernobyl NPP.

    PubMed

    Bailiff, I K; Stepanenko, V F; Göksu, H Y; Bøtter-Jensen, L; Brodski, L; Chumak, V; Correcher, V; Delgado, A; Golikov, V; Jungner, H; Khamidova, L G; Kolizshenkov, T V; Likhtarev, I; Meckbach, R; Petrov, S A; Sholom, S

    2004-01-01

    The cumulative absorbed dose in bricks collected from six buildings in two heavily contaminated settlements (137Cs > 2,000 kBq m(-2)) located downwind of the Chernobyl Nuclear Power Plant was determined using luminescence techniques by six laboratories. The settlements, Vesnianoje in Ukraine and Zaborie in Russia, are located in, respectively, proximal and distal locations relative to the Chernobyl Nuclear Power Plant. The luminescence determinations of cumulative dose in brick, after subtraction of the natural background dose, were translated to absorbed dose in air at a Reference Location using conversion factors derived from Monte Carlo simulations of photon transport. The simulations employed source distributions inferred from contemporary soil contamination data and also took into account heterogeneity of fallout deposition. This translation enables the luminescence determinations to be compared directly with values of cumulative absorbed dose obtained by computational modeling and also other dose reconstruction methods. For each sampled location the cumulative dose was calculated using three deterministic models, two of which are based on the attenuation of dose-rate with migration of radionuclides in soil and the third on historic instrumental gamma dose-rate data. The results of the comparison of the two methods indicate overall agreement within margins of +/-25%. The methodology developed is generally applicable and adaptable to areas contaminated by much lower levels of radioactive fallout in which brick buildings are found. PMID:14695006

  2. Protective coatings for high-temperature polymer matrix composites

    NASA Technical Reports Server (NTRS)

    Harding, David R.; Sutter, James K.; Papadopoulos, Demetrios S.

    1993-01-01

    Plasma-enhanced chemical vapor deposition was used to deposit silicon nitride on graphite-fiber-reinforced polyimide composites to protect against oxidation at elevated temperatures. The adhesion and integrity of the coating were evaluated by isothermal aging (371 C for 500 hr) and thermal cycling. The amorphous silicon nitride (a-SiN:H) coating could withstand stresses ranging from approximately 0.18 GPa (tensile) to -1.6 GPa (compressive) and provided a 30 to 80 percent reduction in oxidation-induced weight loss. The major factor influencing the effectiveness of a-SiN:H as a barrier coating against oxidation is the surface finish of the polymer composite.

  3. Determining the role of polymer molecular weight for high-performance all-polymer solar cells: its effect on polymer aggregation and phase separation.

    PubMed

    Kang, Hyunbum; Uddin, Mohammad Afsar; Lee, Changyeon; Kim, Ki-Hyun; Nguyen, Thanh Luan; Lee, Wonho; Li, Yuxiang; Wang, Cheng; Woo, Han Young; Kim, Bumjoon J

    2015-02-18

    The molecular weight of a conjugated polymer is one of the key factors determining the electrical, morphological, and mechanical properties as well as its solubility in organic solvents and miscibility with other polymers. In this study, a series of semicrystalline poly[(2,5-bis(2-hexyldecyloxy)phenylene)-alt-(5,6-difluoro-4,7-di(thiophen-2-yl)benzo[c][1,2,5]thiadiazole)] (PPDT2FBT) polymers with different number-average molecular weights (M(n)'s) (PPDT2FBT(L), M(n) = 12 kg/mol; PPDT2FBT(M), M(n) = 24 kg/mol; PPDT2FBT(H), M(n) = 40 kg/mol) were synthesized, and their photovoltaic properties as electron donors for all-polymer solar cells (all-PSCs) with poly[[N,N'-bis(2-octyldodecyl)-napthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5'-(2,2'-bithiophene)] (P(NDI2OD-T2)) acceptor were studied. The M(n) effect of PPDT2FBT on the structural, morphological, electrical, and photovoltaic properties was systematically investigated. In particular, tuning the M(n) induced dramatic effects on the aggregation behaviors of the polymers and their bulk heterojunction morphology of all-PSCs, which was thoroughly examined by grazing incident X-ray scattering, resonant soft X-ray scattering, and other microscopy measurements. High M(n) PPDT2FBT(H) promoted a strong "face-on" geometry in the blend film, suppressed the formation of an excessively large crystalline domain, and facilitated molecularly intermixed phases with P(NDI2OD-T2). Therefore, the optimized all-PSCs based on PPDT2FBT(H)/P(NDI2OD-T2) showed substantially higher hole and electron mobilities than those of PPDT2FBT(L)/P(NDI2OD-T2), leading to a power conversion efficiency exceeding 5%, which is one of the highest values for all-PSCs reported thus far. PMID:25605316

  4. Styrene-Butadiene Co-Polymer Based Highly Conducting and Flexible Polymer Composite Film with Low Percolation Threshold

    NASA Astrophysics Data System (ADS)

    Mathew, Anisha Mary; Neena, P.

    2011-10-01

    Conducting polymer composites are finding novel applications in various fields especially in device technology. In this work an effort has been made to synthesize polyaniline-synthetic rubber (Styrene-butadiene rubber) composite via ex-situ technique and its electrochemical properties are investigated. Highly conducting emeraldine form of polyaniline (20 S/cm) is prepared by the oxidative polymerization of aniline in aqueous acidic (CSA) media using ammonium peroxydisulfate as oxidizing agent. These composite films are characterized by UV-Visible spectroscopy to investigate their optical properties. The dc conductivity studies indicate that these composite films show extremely low percolation threshold.

  5. Luminescent Properties of Terbium Aminobenzoates in Condensed Media

    NASA Astrophysics Data System (ADS)

    Meshkova, S. B.; Doga, P. G.; Kiriyak, A. V.; Kucher, A. A.

    2015-07-01

    The decrease in nonradiative deactivation of the luminescence excitation energy in a series of condensed media (true complex solution, viscous solution of water-soluble polymer, polymer fi lm) was studied using terbium complexes with aminobenzoic acids as examples. It was established that the infl uence of the water-soluble polymer was caused by the coordination of Tb3+ to it and the solution viscosity.

  6. Precisely Controlled Ultrathin Conjugated Polymer Films for Large Area Transparent Transistors and Highly Sensitive Chemical Sensors.

    PubMed

    Khim, Dongyoon; Ryu, Gi-Seong; Park, Won-Tae; Kim, Hyunchul; Lee, Myungwon; Noh, Yong-Young

    2016-04-01

    A uniform ultrathin polymer film is deposited over a large area with molecularlevel precision by the simple wire-wound bar-coating method. The bar-coated ultrathin films not only exhibit high transparency of up to 90% in the visible wavelength range but also high charge carrier mobility with a high degree of percolation through the uniformly covered polymer nanofibrils. They are capable of realizing highly sensitive multigas sensors and represent the first successful report of ethylene detection using a sensor based on organic field-effect transistors. PMID:26849096

  7. Crystal growth and characterization studies of novel luminescent 2D coordination polymer of lead-benzilate possessing edge sharing PbO6 polyhedra

    NASA Astrophysics Data System (ADS)

    Soumya Mol, U. S.; Drisya, R.; Satheesh Chandran, P. R.; Sudarsanakumar, M. R.; Suma, S.; Sudhadevi Antharjanam, P. K.

    2016-12-01

    Single crystals of a new coordination polymer of lead-benzilate, C28H21O6Pb·C2H5OH have been successfully grown by gel diffusion technique at room temperature. The colourless single crystals were obtained within a week. The crystal structure was elucidated using single crystal X-ray diffraction studies. The compound possesses a polymeric structure constructed from edge sharing PbO6 polyhedra. Single crystal X-ray diffraction analysis showed that the compound crystallizes in triclinic space group P-1. The grown crystals were further characterized by elemental analysis, FT-IR, UV-Visible and thermogravimetric analysis. The photoluminescent properties of the complex and the ligand were also investigated.

  8. Highly emissive 'frozen-in' conjugated polymer nanofibers.

    PubMed

    Jin, Young-Jae; Lee, Wang-Eun; Lee, Chang-Lyoul; Kwak, Giseop

    2016-05-11

    Conjugated-polymer nanofibers with a thermodynamically stable, coarsened, disordered structure in an amorphous glassy state were fabricated via a freeze-drying method using a poly(diphenylacetylene) derivative. The nanofibers were extremely emissive, with a fluorescence (FL) quantum yield of approximately 0.34, which was much higher than that of both the cast film (0.02) and the solution (0.21). Similarly, the amplitude-weighted average FL lifetime of the nanofibers was 0.74 ns, which was much longer than that of the film (0.29 ns) and the solution (0.57 ns). This unusual and enhanced FL-emission behavior was attributed to the abruptly quenched chain structure that was created by the freeze-drying process. The polymer chains in the nanofibers remained frozen-in and the side phenyl rings were retained in a relaxed state. The metastable chains did not undergo vibrational relaxation and collisional quenching to generate the radiative emission decay effectively. PMID:27109600

  9. Elastic turbulence in high Reynolds number polymer drag reduced flows

    NASA Astrophysics Data System (ADS)

    Dubief, Yves; White, Christopher

    2011-11-01

    The present study discusses the existence of small scale dynamics resembling elastic turbulence in polymeric transitional and maximum drag reduction (MDR) flows. The observed flow patterns are driven by elastic stress and occur in regions of very low turbulence found before and after the breakdown of nonlinear instabilities in polymeric transitional flows leading to MDR. A state of polymer-dominated spanwise instabilities was found, resulting in a structure of the wall shear quite different than the structures observed in transitional Newtonian flow. Similar instabilities are observed in the wake of the head of hairpin vortices in simulated MDR flows, an extended region of extensional flow of the order of the Kolmogorov scale in the normal direction. The important Reynolds number is not that of flow (Reτ = 300 and 600 for the Newtonian flows) but that of the local turbulent flow, which according to Kolmogorov approaches unity in the above mentioned flows, a reasonable magnitude for elastic turbulence. The existence of small scale elastic turbulence in transitional and MDR flows explains the phenomenon of early turbulence first observed in the 70s and challenges the notion that, in drag reduced flows, the energy flows only from large to small scales and never goes back from polymers to flow.

  10. Production of Polymer Core-Shell Colloids with High Uniformity via Coaxial Electrospray

    NASA Astrophysics Data System (ADS)

    Hwang, Yoon Kyun; Jeong, Unyong

    2008-03-01

    Although nanofibers fabricated by electrospinning have been attracting wide interest, the production of colloids by electrospraying has not much studied so far. We have developed a simple method for the production of core-shell colloids with high uniformity by means of the coaxial electrospray. Contrary to usual coaxial setup, the inner nozzle was set to touch the inside wall of the outer nozzle for reproducible production. A polymer solution for the core was introduced through the outer nozzle and another solution for the shell was provided through the inner nozzle. The structure of the colloids was dependent on the polymer concentration, relative feed ratio between the polymer solutions. Especially, core-shell structured colloids are our primary interest due to their promising uses in drug-delivery systems, cosmetics, and food industries. This talk will present the production of core-shell colloids consisting of two polymer components.

  11. Multiplexed Optical Transmission System For Automobiles Using Polymer Fiber With High Heat Resistance

    NASA Astrophysics Data System (ADS)

    Sasayama, Takao; Asano, Hideki; Taketani, Noriaki

    1989-02-01

    A multiplexed optical transmission system for automobiles utilizing newly developed polymer fiber has been proposed. The system is composed with a star-shaped optical network, in which the ootical signals can be transmitted bi-directionally through polymer optical fiber and optical branches with the central and local controllers. The polymer fiber has been developed for this purpose in order to overcome the conventional problems which prevented its wide use for a long time. The new polymer fiber is fabricated with a thereto-setting resin for core which is pushed out from heating furnace after the process of polymerization. The fiber shows the desirable characteristics for this application, that is, the heat resistance is as high as 200°C, and the transmission loss is as low as 0.5003/m at 660 nm wavelength.

  12. LS-DYNA Implementation of Polymer Matrix Composite Model Under High Strain Rate Impact

    NASA Technical Reports Server (NTRS)

    Zheng, Xia-Hua; Goldberg, Robert K.; Binienda, Wieslaw K.; Roberts, Gary D.

    2003-01-01

    A recently developed constitutive model is implemented into LS-DYNA as a user defined material model (UMAT) to characterize the nonlinear strain rate dependent behavior of polymers. By utilizing this model within a micromechanics technique based on a laminate analogy, an algorithm to analyze the strain rate dependent, nonlinear deformation of a fiber reinforced polymer matrix composite is then developed as a UMAT to simulate the response of these composites under high strain rate impact. The models are designed for shell elements in order to ensure computational efficiency. Experimental and numerical stress-strain curves are compared for two representative polymers and a representative polymer matrix composite, with the analytical model predicting the experimental response reasonably well.

  13. Structure of highly rigid ionic polymers from single molecules to membranes

    NASA Astrophysics Data System (ADS)

    He, Lilin; Cornelius, Christopher J.

    2005-03-01

    The structure of ionic polymers in solutions and in their solid state is governed by the segregation to hydrophilic and hydrophobic regions. Very rigid backbones with persistence lengths much larger than the size of the monomer limit the segregation affecting the resulting structure and dynamics of the polymers. Using a newly synthesized para phenylene based sulfonated polymer with a potential to serve as a polymeric electrolytic membrane for fuel cell applications, we followed the structure of highly rigid ionic polymers from a single molecule to a water swollen membranes using small angle neutron scattering and AFM/TEM techniques. AFM and TEM images show that the dry membranes have domains with a diameter from 30 nm to 70nm. Small angle neutron scattering probes the smaller structure in the membranes from dry to swollen states. Fitting to Teubner-Strey model of SANS data indicates the bi-continuous phases were formed with water and ethanol despite the rigidity of the backbone.

  14. High-Performance Carbon Nanotube/Polymer Composite Fiber from Layer-by-Layer Deposition.

    PubMed

    Wu, Min Le; Chen, Yun; Zhang, Liang; Zhan, Hang; Qiang, Lei; Wang, Jian Nong

    2016-03-30

    So far, preparation of high-performance carbon nanotube (CNT)/polymer composites still faces big challenges mainly due to the limited control of CNT dispersion, fraction, and alignment in polymers. Here, a new "layer-by-layer deposition" method is put forward for preparing CNT/polymer composite fibers using poly(vinyl alcohol) (PVA) as an exemplary polymer. This is based on the continuous production of a hollow cylindrical CNT assembly from a high temperature reactor and its shrinking by a PVA-containing solution and deposition on a removable substrate wire. The in situ mixing of the two composite components at the molecular level allows CNTs to disperse and PVA to infiltrate into the fiber efficiently. As a result, remarkable effects of the CNT reinforcement on the PVA matrix are observed, including a strength improvement from ∼50 to 1255 MPa and electrical conductivity from ∼0 to 1948 S cm(-1). The new method offers good controllability of CNT dispersion and fraction in the polymer matrix, variability for making composite fibers using different polymers, and suitability for scaled up production. This study thus provides a new research direction for preparing CNT-reinforced composites and future performance maximization. PMID:26959406

  15. A review of water-soluble polymers used in high temperature oil recovery applications

    SciTech Connect

    Moradi-Araghi, A.

    1993-12-31

    In most oil bearing formations, hydrocarbons are trapped under pressure in the pores of rock matrix. This pressure which is the driving force in Production of hydrocarbons is gradually depleted as oil or gas is produced. Water is commonly injected into such reservoirs to maintain the pressure and produce an additional 10-20% of the original oil in place. However, water tends to pass through the higher permeability zones, fractures or channels, leaving a substantial amount of oil behind. Water-soluble polymers which increase the viscosity of water and thereby, reduce its mobility, are used to recover additional oil. The polymers can also be crosslinked to produce gels which are used to block the high permeability channels or fractures so subsequent water injection can produce additional oil. Both synthetic and natural water-soluble polymers have been used to recover more oil from shallower reservoirs. The hotter (< 90{degrees}C) reservoirs limit the type of polymers which can be used for polymer flooding and gelation. Neither polyacrylamides, nor xanthan gums commonly used for lower temperature reservoirs can tolerate the harsh conditions of the higher temperatures, salinity and hardness encountered in deeper reservoirs. This paper reviews the polymers and gels suitable for use in high temperature reservoirs.

  16. Analytical Modeling of the High Strain Rate Deformation of Polymer Matrix Composites

    NASA Technical Reports Server (NTRS)

    Goldberg, Robert K.; Roberts, Gary D.; Gilat, Amos

    2003-01-01

    The results presented here are part of an ongoing research program to develop strain rate dependent deformation and failure models for the analysis of polymer matrix composites subject to high strain rate impact loads. State variable constitutive equations originally developed for metals have been modified in order to model the nonlinear, strain rate dependent deformation of polymeric matrix materials. To account for the effects of hydrostatic stresses, which are significant in polymers, the classical 5 plasticity theory definitions of effective stress and effective plastic strain are modified by applying variations of the Drucker-Prager yield criterion. To verify the revised formulation, the shear and tensile deformation of a representative toughened epoxy is analyzed across a wide range of strain rates (from quasi-static to high strain rates) and the results are compared to experimentally obtained values. For the analyzed polymers, both the tensile and shear stress-strain curves computed using the analytical model correlate well with values obtained through experimental tests. The polymer constitutive equations are implemented within a strength of materials based micromechanics method to predict the nonlinear, strain rate dependent deformation of polymer matrix composites. In the micromechanics, the unit cell is divided up into a number of independently analyzed slices, and laminate theory is then applied to obtain the effective deformation of the unit cell. The composite mechanics are verified by analyzing the deformation of a representative polymer matrix composite (composed using the representative polymer analyzed for the correlation of the polymer constitutive equations) for several fiber orientation angles across a variety of strain rates. The computed values compare favorably to experimentally obtained results.

  17. Singlet fission of hot excitons in π-conjugated polymers.

    PubMed

    Zhai, Yaxin; Sheng, Chuanxiang; Vardeny, Z Valy

    2015-06-28

    We used steady-state photoinduced absorption (PA), excitation dependence (EXPA(ω)) spectrum of the triplet exciton PA band, and its magneto-PA (MPA(B)) response to investigate singlet fission (SF) of hot excitons into two separated triplet excitons, in two luminescent and non-luminescent π-conjugated polymers. From the high energy step in the triplet EXPA(ω) spectrum of the luminescent polymer poly(dioctyloxy)phenylenevinylene (DOO-PPV) films, we identified a hot-exciton SF (HE-SF) process having threshold energy at E≈2E(T) (=2.8 eV, where ET is the energy of the lowest lying triplet exciton), which is about 0.8 eV above the lowest singlet exciton energy. The HE-SF process was confirmed by the triplet MPA(B) response for excitation at E>2E(T), which shows typical SF response. This process is missing in DOO-PPV solution, showing that it is predominantly interchain in nature. By contrast, the triplet EXPA(ω) spectrum in the non-luminescent polymer polydiacetylene (PDA) is flat with an onset at E=E(g) (≈2.25 eV). From this, we infer that intrachain SF that involves a triplet-triplet pair state, also known as the 'dark' 2A(g) exciton, dominates the triplet photogeneration in PDA polymer as E(g)>2E(T). The intrachain SF process was also identified from the MPA(B) response of the triplet PA band in PDA. Our work shows that the SF process in π-conjugated polymers is a much more general process than thought previously. PMID:25987576

  18. Singlet fission of hot excitons in π-conjugated polymers

    PubMed Central

    Zhai, Yaxin; Sheng, Chuanxiang; Vardeny, Z. Valy

    2015-01-01

    We used steady-state photoinduced absorption (PA), excitation dependence (EXPA(ω)) spectrum of the triplet exciton PA band, and its magneto-PA (MPA(B)) response to investigate singlet fission (SF) of hot excitons into two separated triplet excitons, in two luminescent and non-luminescent π-conjugated polymers. From the high energy step in the triplet EXPA(ω) spectrum of the luminescent polymer poly(dioctyloxy)phenylenevinylene (DOO-PPV) films, we identified a hot-exciton SF (HE-SF) process having threshold energy at E≈2ET (=2.8 eV, where ET is the energy of the lowest lying triplet exciton), which is about 0.8 eV above the lowest singlet exciton energy. The HE-SF process was confirmed by the triplet MPA(B) response for excitation at E>2ET, which shows typical SF response. This process is missing in DOO-PPV solution, showing that it is predominantly interchain in nature. By contrast, the triplet EXPA(ω) spectrum in the non-luminescent polymer polydiacetylene (PDA) is flat with an onset at E=Eg (≈2.25 eV). From this, we infer that intrachain SF that involves a triplet–triplet pair state, also known as the ‘dark’ 2Ag exciton, dominates the triplet photogeneration in PDA polymer as Eg>2ET. The intrachain SF process was also identified from the MPA(B) response of the triplet PA band in PDA. Our work shows that the SF process in π-conjugated polymers is a much more general process than thought previously. PMID:25987576

  19. Design, fabrication and characterization of an arrayable all-polymer microfluidic valve employing highly magnetic rare-earth composite polymer

    NASA Astrophysics Data System (ADS)

    Rahbar, Mona; Shannon, Lesley; Gray, Bonnie L.

    2016-05-01

    We present a new magnetically actuated microfluidic valve that employs a highly magnetic composite polymer (M-CP) containing rare-earth hard-magnetic powder for its actuating element and for its valve seat. The M-CP offers much higher magnetization compared to the soft-magnetic, ferrite-based composite polymers typically used in microfluidic applications. Each valve consists of a permanently magnetized M-CP flap and valve seat mounted on a microfluidic channel system fabricated in poly(dimethylsiloxane) (PDMS). Each valve is actuated under a relatively small external magnetic field of 80 mT provided by a small permanent magnet mounted on a miniature linear actuator. The performance of the valve with different flap thicknesses is characterized. In addition, the effect of the magnetic valve seat on the valve’s performance is also characterized. It is experimentally shown that a valve with a 2.3 mm flap thickness, actuated under an 80 mT magnetic field, is capable of completely blocking liquid flow at a flow rate of 1 ml min‑1 for pressures up to 9.65 kPa in microfluidic channels 200 μm wide and 200 μm deep. The valve can also be fabricated into an array for flow switching between multiple microfluidic channels under continuous flow conditions. The performance of arrays of valves for flow routing is demonstrated for flow rates up to 5 ml min‑1 with larger microfluidic channels of up to 1 mm wide and 500 μm deep. The design of the valves is compatible with other commonly used polymeric microfluidic components, as well as other components that use the same novel permanently magnetic composite polymer, such as our previously reported cilia-based mixing devices.

  20. A highly aromatic and sulfonated ionomer for high elastic modulus ionic polymer membrane micro-actuators

    NASA Astrophysics Data System (ADS)

    Hatipoglu, Gokhan; Liu, Yang; Zhao, Ran; Yoonessi, Mitra; Tigelaar, Dean M.; Tadigadapa, Srinivas; Zhang, Q. M.

    2012-05-01

    A high modulus, sulfonated ionomer synthesized from 4,6-bis(4-hydroxyphenyl)-N,N-diphenyl-1,3,5-triazin-2-amine and 4,4‧-biphenol with bis(4-fluorophenyl)sulfone (DPA-PS:BP) is investigated for ionic polymer actuators. The uniqueness of DPA-PS:BP is that it can have a high ionic liquid (IL) uptake and consequently generates a high intrinsic strain response, which is >1.1% under 1.6 V while maintaining a high elastic modulus (i.e. 600 MPa for 65 vol% IL uptake). Moreover, such a high modulus of the active ionomer, originating from the highly aromatic backbone and side-chain-free structure, allows for the fabrication of free-standing thin film micro-actuators (down to 5 µm thickness) via the solution cast method and focused-ion-beam milling, which exhibits a much higher bending actuation, i.e. 43 µm tip displacement and 180 kPa blocking stress for a 200 µm long and 5 µm thick cantilever actuator, compared with the ionic actuators based on traditional ionomers such as Nafion, which has a much lower elastic modulus (50 MPa) and actuation strain.

  1. Highly sensitive and selective cartap nanosensor based on luminescence resonance energy transfer between NaYF4:Yb,Ho nanocrystals and gold nanoparticles.

    PubMed

    Wang, Zhijiang; Wu, Lina; Shen, Baozhong; Jiang, Zhaohua

    2013-09-30

    Fluorescent detection is an attractive method for the detection of toxic chemicals. However, most chemosensors that are currently utilized in fluorescent detection are based on organic dyes or quantum dots, which suffer from instability, high background noise and interference from organic impurities in solution, which can also be excited by UV radiation. In the present research, we developed a novel NaYF4:Yb,Ho/Au nanocomposite-based chemosensor with high sensitivity (10 ppb) and selectivity over competing analytes for the detection of the insecticide cartap. This nanosensor is excited with a 970-nm laser instead of UV radiation to give an emission peak at 541 nm. In the presence of cartap, the nanocomposites aggregate, resulting in enhanced luminescence resonance energy transfer between the NaYF4:Yb,Ho nanocrystals and the gold nanoparticles, which decreases the emission intensity at 541 nm. The relative luminescence intensity at 541 nm has a linear relationship with the concentration of cartap in the solution. Based on this behavior, the developed nanosensor successfully detected cartap in farm produce and water samples with satisfactory results. PMID:23953451

  2. A Robust Luminescent Tb(III)-MOF with Lewis Basic Pyridyl Sites for the Highly Sensitive Detection of Metal Ions and Small Molecules.

    PubMed

    Zhao, Jun; Wang, Ye-Nan; Dong, Wen-Wen; Wu, Ya-Pan; Li, Dong-Sheng; Zhang, Qi-Chun

    2016-04-01

    A new luminescent terbium-metal-organic framework [Tb3(L)2(HCOO)(H2O)5]·DMF·4H2O (1) (H4L = 4,4'-(pyridine-3,5-diyl)diisophthalic acid) has been successfully assembled by Tb(3+) ions and an undeveloped pyridyl-tetracarboxylate. Compound 1 exhibits a 3D porous (3,8)-connected (4.5(2))2(4(2).5(12).6(6).7(5).8(3)) topological framework with fascinating 1D open hydrophilic channels decorated by uncoordinated Lewis basic pyridyl nitrogen atoms. In particular, the Tb-MOF (1) can detect Cu(2+) ions with high selectivity and sensitivity, and its luminescence is nearly entirely quenched in N,N-dimethylformamide (DMF) solution and biological system. In addition, 1 still has high detection for the trace content of nitromethane with 70 ppm, which suggests that 1 is a promising example of dual functional materials with sensing copper ions and nitromethane. PMID:26967044

  3. Tin-based inorganic-organic hybrid polymers for high energy-density applications

    NASA Astrophysics Data System (ADS)

    Tran, Huan; Kuma, Arun; Pilania, Ghanshyam; Ramprasad, Rampi

    2014-03-01

    In one of our recent works[1], an organotin polymer was synthesized and suggested to be promising polymeric dielectric, simultaneously exhibiting a high dielectric constant ɛ and a high band gap Eg. Motivated by this result, we study a family of inorganic-organic hybrid polymers based on -(SnF2) x-(CH2) y - as the repeating structural unit (x = 2 , y = 4 , 8 , and 12). The stable structures of these hybrid polymers, predicted by the minima-hopping method, are studied by first-principles calculations at the level of density functional theory. Our calculations show that these polymers are wide band gap materials (up to 6.07 eV). In addition, their dielectric constants are between 4.6 and 7.8, well above that of polypropylene (ɛ ~= 2 . 2), the standard dielectric material for high energy-density capacitors. Therefore, we suggest that the hybrid polymers based on -(SnF2) x-(CH2) y - are promising candidates for high energy-density applications. Our work is supported by the Office of Naval Research through the Multidisciplinary University Research Initiative (MURI).

  4. A high-order external distributed feedback polymer laser with low working threshold

    NASA Astrophysics Data System (ADS)

    Huang, Wenbin; Pu, Donglin; Yang, Xiaofei; Wei, Guojun; Fang, Zongbao; Zhou, Xiaohong; Qiao, Wen; Chen, Linsen

    2016-05-01

    In this paper, we report a high-order distributed feedback (DFB) polymer laser with low working threshold. Using the high-order grating increases the lithographic tolerances, providing coherent light sources that are more amenable to mass-manufacturing techniques, such as laser direct writing lithography and roll-to-roll processing. To enable high-order DFB lasing, an unconventional working configuration is designed in which the grating is situated on top of the uniform conjugated polymer film. In addition, a novel Forster energy transfer blend of two conjugated polymers is used as the gain medium. Upon pumping, the device emits lasing around 603.6 nm with a bandwidth of 0.5 nm. The threshold is around 20.5 μJ cm‑2 (~2.56 kW cm‑2), about to enter the regime of inexpensive LED pumping. A further increase in pump energy results in simultaneous oscillations at the 29th and 30th Bragg orders. Operating principles of the high-order DFB polymer laser, including spectral performance and threshold dependence on pump length, are investigated. This approach represents a step towards low-cost, even ‘disposable’ polymer lasers.

  5. Self-illuminating quantum dots for highly sensitive in vivo real-time luminescent mapping of sentinel lymph nodes.

    PubMed

    Wu, Qiang; Chu, Maoquan

    2012-01-01

    Quantum dots (QDs) show promise as novel nanomaterials for sentinel lymph node (SLN) mapping through their use in noninvasive in vivo fluorescence imaging, and they have provided remarkable results. However, in vivo fluorescence imaging has limitations mainly reflected in the strong autofluorescence and low deepness of tissue penetration associated with this technique. Here, we report on the use of self-illuminating 3-mercaptopropionic acid-capped CdTe/CdS QDs for mouse axillary SLN mapping by bioluminescence resonance energy transfer, which was found to overcome these limitations [corrected]. We used CdTe/CdS QDs synthesized in aqueous solution to conjugate a mutant of the bioluminescent protein, Renilla reniformis luciferase. The nanobioconjugates obtained had an average hydrodynamic diameter of 19 nm, and their luminescence catalyzed by the substrate (coelenterazine) could penetrate into at least 20 mm of hairless pigskin, which could be observed using an in vivo imaging system equipped with a 700 nm emission filter. Conversely, the fluorescence of the nanobioconjugates penetrated no more than 10 mm of pigskin and was observed with a strong background. When 80 μL of the nanobioconjugates (containing about 0.5 μmol/L of QDs) and 5 μL of coelenterazine (1 μg/μL) were intradermally injected into a mouse paw, the axillary SLN could be imaged in real time without external excitation, and little background interference was detected. Furthermore, the decayed luminescence of QD-Luc8 in SLNs could be recovered after being intradermally reinjected with the coelenterazine. Our data showed that using self-illuminating QDs, as opposed to fluorescence QDs, has greatly enhanced sensitivity in SLN mapping, and that the SLN could be identified synchronously by the luminescence and fluorescence of the self-illuminating QDs. PMID:22848169

  6. Liquid immersion thermal crosslinking of 3D polymer nanopatterns for direct carbonisation with high structural integrity.

    PubMed

    Kang, Da-Young; Kim, Cheolho; Park, Gyurim; Moon, Jun Hyuk

    2015-01-01

    The direct pyrolytic carbonisation of polymer patterns has attracted interest for its use in obtaining carbon materials. In the case of carbonisation of nanopatterned polymers, the polymer flow and subsequent pattern change may occur in order to relieve their high surface energies. Here, we demonstrated that liquid immersion thermal crosslinking of polymer nanopatterns effectively enhanced the thermal resistance and maintained the structure integrity during the heat treatment. We employed the liquid immersion thermal crosslinking for 3D porous SU8 photoresist nanopatterns and successfully converted them to carbon nanopatterns while maintaining their porous features. The thermal crosslinking reaction and carbonisation of SU8 nanopatterns were characterised. The micro-crystallinity of the SU8-derived carbon nanopatterns was also characterised. The liquid immersion heat treatment can be extended to the carbonisation of various polymer or photoresist nanopatterns and also provide a facile way to control the surface energy of polymer nanopatterns for various purposes, for example, to block copolymer or surfactant self-assemblies. PMID:26677949

  7. High Strain Rate Deformation Modeling of a Polymer Matrix Composite. Part 1; Matrix Constitutive Equations

    NASA Technical Reports Server (NTRS)

    Goldberg, Robert K.; Stouffer, Donald C.

    1998-01-01

    Recently applications have exposed polymer matrix composite materials to very high strain rate loading conditions, requiring an ability to understand and predict the material behavior under these extreme conditions. In this first paper of a two part report, background information is presented, along with the constitutive equations which will be used to model the rate dependent nonlinear deformation response of the polymer matrix. Strain rate dependent inelastic constitutive models which were originally developed to model the viscoplastic deformation of metals have been adapted to model the nonlinear viscoelastic deformation of polymers. The modified equations were correlated by analyzing the tensile/ compressive response of both 977-2 toughened epoxy matrix and PEEK thermoplastic matrix over a variety of strain rates. For the cases examined, the modified constitutive equations appear to do an adequate job of modeling the polymer deformation response. A second follow-up paper will describe the implementation of the polymer deformation model into a composite micromechanical model, to allow for the modeling of the nonlinear, rate dependent deformation response of polymer matrix composites.

  8. Liquid immersion thermal crosslinking of 3D polymer nanopatterns for direct carbonisation with high structural integrity

    NASA Astrophysics Data System (ADS)

    Kang, Da-Young; Kim, Cheolho; Park, Gyurim; Moon, Jun Hyuk

    2015-12-01

    The direct pyrolytic carbonisation of polymer patterns has attracted interest for its use in obtaining carbon materials. In the case of carbonisation of nanopatterned polymers, the polymer flow and subsequent pattern change may occur in order to relieve their high surface energies. Here, we demonstrated that liquid immersion thermal crosslinking of polymer nanopatterns effectively enhanced the thermal resistance and maintained the structure integrity during the heat treatment. We employed the liquid immersion thermal crosslinking for 3D porous SU8 photoresist nanopatterns and successfully converted them to carbon nanopatterns while maintaining their porous features. The thermal crosslinking reaction and carbonisation of SU8 nanopatterns were characterised. The micro-crystallinity of the SU8-derived carbon nanopatterns was also characterised. The liquid immersion heat treatment can be extended to the carbonisation of various polymer or photoresist nanopatterns and also provide a facile way to control the surface energy of polymer nanopatterns for various purposes, for example, to block copolymer or surfactant self-assemblies.

  9. Approaching disorder-free transport in high-mobility conjugated polymers.

    PubMed

    Venkateshvaran, Deepak; Nikolka, Mark; Sadhanala, Aditya; Lemaur, Vincent; Zelazny, Mateusz; Kepa, Michal; Hurhangee, Michael; Kronemeijer, Auke Jisk; Pecunia, Vincenzo; Nasrallah, Iyad; Romanov, Igor; Broch, Katharina; McCulloch, Iain; Emin, David; Olivier, Yoann; Cornil, Jerome; Beljonne, David; Sirringhaus, Henning

    2014-11-20

    Conjugated polymers enable the production of flexible semiconductor devices that can be processed from solution at low temperatures. Over the past 25 years, device performance has improved greatly as a wide variety of molecular structures have been studied. However, one major limitation has not been overcome; transport properties in polymer films are still limited by pervasive conformational and energetic disorder. This not only limits the rational design of materials with higher performance, but also prevents the study of physical phenomena associated with an extended π-electron delocalization along the polymer backbone. Here we report a comparative transport study of several high-mobility conjugated polymers by field-effect-modulated Seebeck, transistor and sub-bandgap optical absorption measurements. We show that in several of these polymers, most notably in a recently reported, indacenodithiophene-based donor-acceptor copolymer with a near-amorphous microstructure, the charge transport properties approach intrinsic disorder-free limits at which all molecular sites are thermally accessible. Molecular dynamics simulations identify the origin of this long sought-after regime as a planar, torsion-free backbone conformation that is surprisingly resilient to side-chain disorder. Our results provide molecular-design guidelines for 'disorder-free' conjugated polymers. PMID:25383522

  10. Liquid immersion thermal crosslinking of 3D polymer nanopatterns for direct carbonisation with high structural integrity

    PubMed Central

    Kang, Da-Young; Kim, Cheolho; Park, Gyurim; Moon, Jun Hyuk

    2015-01-01

    The direct pyrolytic carbonisation of polymer patterns has attracted interest for its use in obtaining carbon materials. In the case of carbonisation of nanopatterned polymers, the polymer flow and subsequent pattern change may occur in order to relieve their high surface energies. Here, we demonstrated that liquid immersion thermal crosslinking of polymer nanopatterns effectively enhanced the thermal resistance and maintained the structure integrity during the heat treatment. We employed the liquid immersion thermal crosslinking for 3D porous SU8 photoresist nanopatterns and successfully converted them to carbon nanopatterns while maintaining their porous features. The thermal crosslinking reaction and carbonisation of SU8 nanopatterns were characterised. The micro-crystallinity of the SU8-derived carbon nanopatterns was also characterised. The liquid immersion heat treatment can be extended to the carbonisation of various polymer or photoresist nanopatterns and also provide a facile way to control the surface energy of polymer nanopatterns for various purposes, for example, to block copolymer or surfactant self-assemblies. PMID:26677949

  11. Synthesis of molecularly imprinted polymer nanoparticles for the fast and highly selective adsorption of sunset yellow.

    PubMed

    Zhang, Yu; Xie, Zhihai; Teng, Xiaoxiao; Fan, Jin

    2016-04-01

    Novel molecularly imprinted polymer nanoparticles were synthesized by precipitation polymerization with sunset yellow as the template and [2-(methacryloyloxy)ethyl] trimethylammonium chloride as the functional monomer. The molecularly imprinted polymer nanoparticles were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, and their specific surface area and thermal stability were measured. The molecularly imprinted polymer nanoparticles had a high adsorption capacity in wide pH range (pH 1-8) for sunset yellow. The adsorption equilibrium only needed 5 min, and the quantitative desorption was very fast (1 min) by using 10.0 mol/L HCl as the eluant. The maximum adsorption capacity of the molecularly imprinted polymer nanoparticles for sunset yellow was 144.6 mg/g. The adsorption isotherm and kinetic were well consistent with Langmuir adsorption model and pseudo-second-order kinetic model, respectively. The relative selectivity coefficients of the molecularly imprinted polymer nanoparticles for tartrazine and carmine were 9.766 and 12.64, respectively. The prepared molecularly imprinted polymer nanoparticles were repeatedly used and regenerated ten times without significant absorption capacity decrease. PMID:26899416

  12. Assembly of polythiophenes on responsive polymer microgels for the highly selective detection of ammonia gas

    DOE PAGESBeta

    Chang, Aiping; Peng, Yahui; Li, Zezhou; Yu, Xiang; Hong, Kunlun; Zhou, Shuiqin; Wu, Weitai

    2016-04-05

    For this study, a class of smart composite materials based on the assembly of conjugated polymers on responsive polymer microgels has been prepared. We have chosen poly(3-((2-(2-methoxyethoxy)ethoxy)methyl)-thiophene) as the model conjugated polymer and an ammonia-responsive microgel of phenoxazinium-functionalized poly(N-isopropylacrylamide-co-propargyl acrylate) as the model template. Under this design, the composite materials can combine the electrical conductivity of the conjugated polymers and the ammonia recognisability of the ammonia-responsive polymer microgels; the cooperation of these properties allows the reversible control of electrical conductivity by ammonia gas. Those composite materials can not only adapt to ammonia gas, but also convert changes in the concentrationmore » of ammonia into conductance, allowing the electrical detection of ammonia gas with high selectivity. This makes the composite materials different from the conductive polymer platforms reported previously, which may also respond to non-ammonia gases and the response induced by non-ammonia gases is close to that induced by ammonia gas. Using these composite materials as sensing materials for the electrical detection of ammonia gas, the detection limit can reach as low as 1.1 ppb. Finally, these features enable their use for the electrical detection of ammonia in breath.« less

  13. Dual Emissive-Reflective Display Materials with Large Emission Switching Using Highly Luminescent Lanthanide(III) Complex and Electrochromic Material

    NASA Astrophysics Data System (ADS)

    Kanazawa, Kenji; Nakamura, Kazuki; Kobayashi, Norihisa

    2013-05-01

    Electroswitching of emission and coloration was achieved by a combination of a luminescent Eu(III) complex and an electrochromic molecule of diheptyl viologen (HV2+), in order to utilize them as novel display devices with dual emissive-reflective modes. The coloration was associated with the HV2+ electrochromism. Emission control was also achieved by the HV2+ electrochromism via intermolecular energy transfer from the excited state of the Eu(III) ion to the HV+. In order to improve ON-OFF contrast in emission, the emission quantum yield of Eu(III) complex were considerably improved using low vibrational phosphine oxide ligands, resulting in the large control of emission switching.

  14. Ultrathin Polyaniline-based Buffer Layer for Highly Efficient Polymer Solar Cells with Wide Applicability

    PubMed Central

    Zhao, Wenchao; Ye, Long; Zhang, Shaoqing; Fan, Bin; Sun, Mingliang; Hou, Jianhui

    2014-01-01

    Interfacial buffer layers often attribute the improved device performance in organic optoelectronic device. Herein, a water-soluble hydrochloric acid doped polyanilines (HAPAN) were utilized as p-type electrode buffer layer in highly efficient polymer solar cells (PSC) based on PBDTTT-EFT and several representative polymers. The PBDTTT-EFT-based conventional PSC featuring ultrathin HAPAN (1.3 nm) delivered high PCE approximately 9%, which is one of the highest values among conventional PSC devices. Moreover, ultrathin HAPAN also exhibited wide applicability in a variety of efficient photovoltaic polymers including PBDTTT-C-T, PTB7, PBDTBDD, PBTTDPP-T, PDPP3T and P3HT. The excellent performances were originated from the high transparency, small film roughness and suitable work function. PMID:25300365

  15. High contrast ratio and fast-switching dual polymer electrochromic devices

    SciTech Connect

    Sapp, S.A.; Sotzing, G.A.; Reynolds, J.R.

    1998-08-01

    A series of dual polymer electrochromic devices (ECDs) based on 12 complementary pairs of conducting polymer films have been constructed using 3,4-ethylenedioxythiophene-containing conducting polymers. Poly[3,6-bis(2-(3,4-ethylenedioxythiophene))-N-methylcarbazole] (PBEDOT-NCH{sub 3}Cz), poly[3,6-bis(2-(3,4-ethylenedioxythiophene))-N-eicosylcarbazole] (PBEDOT-NC{sub 20}H{sub 41}Cz), and poly[4,4{prime}-bis(2-(3,4-ethylenedioxythiophene))biphenyl] (PBEDOT-BP) were utilized as anodically coloring polymers that electrochemically switch between an oxidized deep blue absorptive state and a transmissive (orange or yellow) reduced state. Poly(3,4-ethylenedioxythiophene)(PEDOT) and its alkyl derivatives (PEDOT-C{sub 14}H{sub 29} and PEDOT-C{sub 16}H{sub 33}) have been used as high-contrast cathodically coloring polymers that switch between a deep blue absorptive state in the reduced form and a sky blue, highly transmissive state in the oxidized form. The dual polymer ECDs were constructed by separating complementary pairs of EC polymer films, deposited on ITO glass, with a gel electrolyte composed of a lithium salt and plasticized poly(methyl methacrylate) (PMMA). Device contrast ratios, measured as {Delta}%T, ranged from 27% to 63%, and subsecond switching times for full color change were achieved. These devices were found to exhibit extremely high coloration efficiencies of up to 1400 cm{sup 2}/C over narrow (ca. 100 nm) wavelength ranges and to retain up to 60% of their optical response after 10,000 deep, double potential steps, rendering them useful for EC applications.

  16. Highly porous organic polymers bearing tertiary amine group and their exceptionally high CO2 uptake capacities

    NASA Astrophysics Data System (ADS)

    Gomes, Ruth; Bhaumik, Asim

    2015-02-01

    We report a very simple and unique strategy for synthesis of a tertiary amine functionalized high surface area porous organic polymer (POP) PDVTA-1 through the co-polymerization of monomers divinylbenzene (DVB) and triallylamine (TAA) under solvothermal reaction conditions. Two different PDVTA-1 samples have been synthesized by varying the molar ratio of the monomers. The porous polymeric materials have been thoroughly characterized by solid state 13C CP MAS-NMR, FT-IR and UV-vis spectroscopy, N2 sorption, HR TEM and FE SEM to understand its chemical environment, nanostructure, bonding, morphology and related surface properties. PDVTA-1 with higher amine content (DVB/TAA=4.0) showed exceptionally high CO2 uptake capacity of 85.8 wt% (19.5 mmol g-1) at 273 K and 43.69 wt% (9.93 mmol g-1) at 298 K under 3 bar pressure, whereas relatively low amine loaded material (DVB/TAA=7.0) shows uptake capacity of 59.2 wt% (13.45 mmol g-1) at 273 K and 34.36 wt% (7.81 mmol g-1) at 298 K. Highly porous nanostructure together with very high surface area and basicity at the surface due to the presence of abundant basic tertiary amine N-sites in the framework of PDVTA-1 could be responsible for very high CO2 adsorption.

  17. A Fiber Supercapacitor with High Energy Density Based on Hollow Graphene/Conducting Polymer Fiber Electrode.

    PubMed

    Qu, Guoxing; Cheng, Jianli; Li, Xiaodong; Yuan, Demao; Chen, Peining; Chen, Xuli; Wang, Bin; Peng, Huisheng

    2016-05-01

    A hollow graphene/conducting polymer composite fiber is created with high mechanical and electronic properties and used to fabricate novel fiber-shaped supercapacitors that display high energy densities and long life stability. The fiber supercapacitors can be woven into flexible powering textiles that are particularly promising for portable and wearable electronic devices. PMID:27001216

  18. Enhanced luminescence properties of highly threaded conjugated polyelectrolytes with potassium counter-ions upon blending with poly(ethylene oxide)

    NASA Astrophysics Data System (ADS)

    Latini, Gianluca; Winroth, Gustaf; Brovelli, Sergio; McDonnell, Shane O.; Anderson, Harry L.; Mativetsky, Jeffrey M.; Samorı, Paolo; Cacialli, Franco

    2010-06-01

    The photophysics and electroluminescence (EL) of thin films of unthreaded and cyclodextrin-encapsulated poly(4,4'-diphenylenevinylene) (PDV) with potassium countercations, blended with poly(ethylene oxide) (PEO) are investigated as a function of the PEO concentration. We show that three main factors contribute to increasing the photoluminescence (PL) quantum efficiency as a result of suppressed intermolecular interactions, namely: the high degree of encapsulation of the polyrotaxanes, the relatively large countercation (e.g., compared to lithium), and the complexation of the rotaxanes with PEO. By facilitating cationic transport to the negative electrodes, PEO also leads to devices with enhanced electron injection and improved charge balance, whose operation therefore resembles that of "virtually unipolar" light-emitting electrochemical cells. This effect, together with the enhanced PL efficiency, leads to higher EL efficiency for both polyrotaxanes and unthreaded polymers, upon addition of the PEO. We show that the concurrent exploitation of the various strategies above lead to an overall EL efficiency that is approximately twice the value previously reported for Li-based PDV. A blueshift of the EL spectrum during the devices turn-on is also reported and analyzed in terms of interference and doping effects.

  19. Importance of Having Low-Density Functional Groups for Generating High-Performance Semiconducting Polymer Dots

    PubMed Central

    Zhang, Xuanjun; Yu, Jiangbo; Wu, Changfeng; Jin, Yuhui; Rong, Yu; Ye, Fangmao

    2012-01-01

    Semiconducting polymers with low-density side-chain carboxylic acid groups were synthesized to form stable, functionalized, and highly fluorescent polymer dots (Pdots). The influence of the molar fraction of hydrophilic side-chains on Pdot properties and performance was systematically investigated. Our results show that the density of side-chain carboxylic acid groups significantly affects Pdot stability, internal structure, fluorescence brightness, and nonspecific binding in cellular labeling. Fluorescence spectroscopy, single-particle imaging, and a dye-doping method were employed to investigate the fluorescence brightness and the internal structure of the Pdots. The results of these experiments indicate that semiconducting polymers with low density of side-chain functional groups can form stable, compact, and highly bright Pdots as compared to those with high density of hydrophilic side-chains. The functionalized polymer dots were conjugated to streptavidin (SA) by carbodiimide-catalyzed coupling and the Pdot-SA probes effectively and specifically labeled the cancer cell-surface marker Her2 in human breast cancer cells. The carboxylate-functionalized polymer could also be covalently modified with small functional molecules to generate Pdot probes for click chemistry-based bioorthogonal labeling. This study presents a promising approach for further developing functional Pdot probes for biological applications. PMID:22607220

  20. Luminescence-induced photorefractive spatial solitons

    NASA Astrophysics Data System (ADS)

    Fazio, E.; Alonzo, M.; Devaux, F.; Toncelli, A.; Argiolas, N.; Bazzan, M.; Sada, C.; Chauvet, M.

    2010-03-01

    We report the observation of spatial confinement of a pump beam into a photorefractive solitonic channel induced by luminescence [luminescence induced spatial soliton (LISS)]. Trapped beams have been obtained in erbium doped lithium niobate crystals at concentrations as high as 0.7 mol % of erbium. By pumping at 980 nm, erbium ions emit photons at 550 nm by two-step absorption, wavelength which can be absorbed by lithium niobate and originates the photorefractive effect. The luminescence at 550 nm generates at the same time the solitonic channel and the background illumination reaching a steady-state soliton regime.

  1. Spectrometer for cluster ion beam induced luminescence

    SciTech Connect

    Ryuto, H. Sakata, A.; Takeuchi, M.; Takaoka, G. H.; Musumeci, F.

    2015-02-15

    A spectrometer to detect the ultra-weak luminescence originated by the collision of cluster ions on the surfaces of solid materials was constructed. This spectrometer consists of 11 photomultipliers with band-pass interference filters that can detect the luminescence within the wavelength ranging from 300 to 700 nm and of a photomultiplier without filter. The calibration of the detection system was performed using the photons emitted from a strontium aluminate fluorescent tape and from a high temperature tungsten filament. Preliminary measurements show the ability of this spectrometer to detect the cluster ion beam induced luminescence.

  2. Assemblies of a new flexible multicarboxylate ligand and d10 metal centers toward the construction of homochiral helical coordination polymers: structures, luminescence, and NLO-active properties.

    PubMed

    Zang, Shuangquan; Su, Yang; Li, Yizhi; Ni, Zhaoping; Meng, Qingjin

    2006-01-01

    Hydro(solvo)thermal reactions between a new flexible multicarboxylate ligand of 2,2',3,3'-oxydiphthalic acid (2,2',3,3'-H(4)ODPA) and M(NO(3))(2).xH(2)O (M = Zn, x = 6; M = Cd, x = 4) in the presence of 4,4'-bipyridine (bpy) afford two novel homochiral helical coordination polymers [[Zn(2)(2,2',3,3'-ODPA)(bpy)(H(2)O)(3)].(H(2)O)(2) for 1 and [Cd(2)(2,2',3,3'-ODPA)(bpy)(H(2)O)(3)].(H(2)O)(2) for 2]. Though having almost the same chemical formula, they have different space groups (P2(1)2(1)2(1) for 1 and P2(1) for 2) and different bridging modes of the 2,2',3,3'-ODPA ligand. Two kinds of homochiral helices (right-handed) are found in both 1 and 2, each of which discriminates only one kind of crystallographical nonequivalent metal atom. 1 has a 2D metal-organic framework and can be seen as the unity of two parallel homochiral Zn1 and Zn2 helices, in which the nodes are etheric oxygen atoms. In contrast, 2 has a 3D metal-organic framework and consists of two partially overlapped homochiral Cd1 and Cd2 helices in the two dimensions. Moreover, metal-ODPA helices give a 2D chiral herringbone structural motif in both 1 and 2 in the two dimensions, which are further strengthened by the second ligand of bpy. Bulk materials for 1 and 2 all have good second-harmonic generation activity, approximately 1 and 0.8 times that of urea. PMID:16390053

  3. High-performance solid polymer electrolytes for lithium batteries operational at ambient temperature

    NASA Astrophysics Data System (ADS)

    Mindemark, Jonas; Sun, Bing; Törmä, Erik; Brandell, Daniel

    2015-12-01

    Incorporation of carbonate repeating units in a poly(ε-caprolactone) (PCL) backbone used as a host material in solid polymer electrolytes is found to not only suppress crystallinity in the polyester material, but also give higher ionic conductivity in a wide temperature range exceeding the melting point of PCL crystallites. Combined with high cation transference numbers, this electrolyte material has sufficient lithium transport properties to be used in battery cells that are operational at temperatures down to below 23 °C, thus clearly demonstrating the potential of using non-polyether electrolytes in high-performance all-solid lithium polymer batteries.

  4. Depth-resolved holographic optical coherence imaging using a high-sensitivity photorefractive polymer device

    NASA Astrophysics Data System (ADS)

    Salvador, M.; Prauzner, J.; Köber, S.; Meerholz, K.; Jeong, K.; Nolte, D. D.

    2008-12-01

    We present coherence-gated holographic imaging using a highly sensitive photorefractive (PR) polymer composite as the recording medium. Due to the high sensitivity of the composite holographic recording at intensities as low as 5 mW/cm2 allowed for a frame exposure time of only 500ms. Motivated by regenerative medical applications, we demonstrate optical depth sectioning of a polymer foam for use as a cell culture matrix. An axial resolution of 18 μm and a transverse resolution of 30 μm up to a depth of 600 μm was obtained using an off-axis recording geometry.

  5. Design and Development of Highly Sulfonated Polymers as Proton Exchange Membranes for High Temperature Fuel Cell Applications

    NASA Astrophysics Data System (ADS)

    Dang, Thuy D.; Bai, Zongwu; Yoonessi, Mitra

    A series of high molecular weight, highly sulfonated poly(arylenethioethersulfone) (SPTES) polymers were synthesized by polycondensation, which allowed controlled sulfonation of up to 100 mol %. The SPTES polymers were prepared via step growth polymerization of sulfonated aromatic difluorosulfone, aromatic difluorosulfone, and 4,4 '-thiobisbenzenthiol in sulfolane solvent at the temperature up to 180 °C. The composition and incorporation of the sulfonated repeat unit into the polymers were confirmed by 1H nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) spectroscopy. Solubility tests on the SPTES polymers confirmed that no cross-linking and probably no branching occurred during the polymerizations. The end-capping groups were introduced in the SPTES polymers to control the molecular weight distribution and reduce the water solubility of the polymers. Tough, ductile membranes formed via solvent-casting exhibited increased water absorption with increasing degrees of sulfonation. The polymerizations conducted with the introduction of end-capping groups resulted in a wide variation in polymer proton conductivity, which spanned a range of 100 -300 mS cm-1, measured at 65 °C and 85 % relative humidity. The measured proton conductivities at elevated temperatures and high relative humidities are up to three times higher than that of the state-of-the-art Nafion-H proton exchange membrane under nearly comparable conditions. The thermal and mechanical properties of the SPTES polymers were investigated by TGA, DMA, and tensile measurements. The SPTES polymers show high glass transition temperatures (Tg), ˜220 °C, depending on the degree of sulfonation in polymerization. SPTES-50 polymer shows a Tg of 223 °C, with high tensile modulus, high tensile strengths at break and at yield as well as elongation at break. Wide angle X-ray scattering of the polymers shows two broad scattering features centered at 4.5 Å and 3.3 Å, the latter peak being

  6. High Modulus, High Conductivity Nanostructured Polymer Electrolyte Membranes via Polymerization-Induced Phase Separation

    NASA Astrophysics Data System (ADS)

    McIntosh, Lucas; Schulze, Morgan; Hillmyer, Marc; Lodge, Timothy

    2014-03-01

    Solvent-free, solid-state polymer electrolyte membranes (PEMs) will play a vital role in next-generation electrochemical devices such as Li-metal batteries and high- T fuel cells. The primary challenge is that these applications require PEMs with substantial mechanical robustness, as well as high ionic conductivity. The key to optimizing orthogonal macroscopic properties is to use a heterogeneous composite with well-defined nanoscopic morphology--specifically, long-range co-continuity of high modulus and ion transport domains, which has proven difficult to achieve in commonly-studied diblock copolymer-based electrolytes. We report a simple synthetic strategy to generate PEMs via polymerization-induced phase separation, where the delicate balance between controlled addition of styrene onto a poly(ethylene oxide) macro-chain transfer agent and simultaneous chemical crosslinking by divinylbenzene results in a disordered structure with domain size of order 10 nm. Crucially, both domains exhibit long-range continuity, which results in PEMs that are glassy solids (modulus ~ 1 GPa) owing to the isotropic network of stiff, crosslinked polystyrene, and are highly conductive (> 1 mS/cm at 70 °C) because ions migrate in channels of low Tg poly(ethylene oxide).

  7. Highly uniform and monodisperse GdOF:Ln3+ (Ln = Eu, Tb, Tm, Dy, Ho, Sm) microspheres: hydrothermal synthesis and tunable-luminescence properties.

    PubMed

    Zhang, Yang; Kang, Xiaojiao; Geng, Dongling; Shang, Mengmeng; Wu, Yuan; Li, Xuejiao; Lian, Hongzhou; Cheng, Ziyong; Lin, Jun

    2013-10-21

    GdOF:Ln(3+) (Ln = Eu, Tb, Tm, Dy, Ho and Sm) microspheres (1.5 μm) with high uniformity and monodispersity have been synthesized via a facile hydrothermal method followed by heat treatment (600 °C). X-Ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), as well as photoluminescence (PL) and cathodoluminescence (CL) spectra are used to characterize the resulting samples. A series of controlled experiments indicate that sodium citrate (Cit(3-)) as a shape modifier introduced into the reaction system plays a critical role in the shape evolution of the final products. Furthermore, the shape and size of the products can be further manipulated by adjusting the dosage of Cit(3-) and pH values in the initial solution. The possible formation mechanism for these microspheres has been presented. Under UV light and low-voltage electron beam excitation, GdOF:Ln(3+) microspheres show the characteristic f-f transitions of Ln(3+) (Eu, Tb/Ho, Tm, Dy and Sm) ions and give bright red, green, blue, yellow and yellowish-orange emission, respectively. In addition, multicolored luminescence containing white emission have been successfully confected for co-doped GdOF:Ln(3+) phosphors by changing the doped Ln(3+) ions and adjusting their doping concentrations due to the simultaneous luminescence of Ln(3+) in the GdOF host, making these materials have potential applications in field-emission display devices. PMID:23942823

  8. Three-Photon Luminescence of Gold Nanorods Excited by 1040 nm Femtosecond Laser for High Contrast Tissue and In Vivo Imaging

    NASA Astrophysics Data System (ADS)

    Wang, Shaowei; Zhao, Xinyuan; Zhang, Hequn; Cai, Fuhong; Qian, Jun

    2016-01-01

    Gold Nanorods (GNRs) with tunable aspect ratios can strongly absorb and scatter light in the NIR region due to their localized surface plasmon resonance (LSPR) property, and have been demonstrated to exhibit strong plasmon enhanced multiphoton luminescence (MPL) with brightness many times stronger than the conventional organic chromophores. In this study, we synthesized GNRs with longitudinal LSPR peak at 1036 nm to match our home-built light source 1040 nm femtosecond laser, which locates in the “optical window” where the tissue absorbs relatively little light. PEGylated GNRs with great biocompatibility were intravenously injected through the tail vein into mice. Excited by 1040 nm laser, the GNRs exhibit bright three-photon luminescence (3PL) signals while circulating in the blood vessels. The use of GNRs as bright contrast agents for 3PL imaging of mouse ear blood vessels in vivo was demonstrated. And GNRs targeted in tissues can be excited by 1040 nm laser and could be clearly visualized with no autofluorescence background. These results indicated that 3PL of GNRs is very promising for deep in vivo bioimaging and assessing the distribution of GNRs in tissues with high contrast.

  9. Facile preparation of highly luminescent CdTe quantum dots within hyperbranched poly(amidoamine)s and their application in bio-imaging

    PubMed Central

    2014-01-01

    A new strategy for facile preparation of highly luminescent CdTe quantum dots (QDs) within amine-terminated hyperbranched poly(amidoamine)s (HPAMAM) was proposed in this paper. CdTe precursors were first prepared by adding NaHTe to aqueous Cd2+ chelated by 3-mercaptopropionic sodium (MPA-Na), and then HPAMAM was introduced to stabilize the CdTe precursors. After microwave irradiation, highly fluorescent and stable CdTe QDs stabilized by MPA-Na and HPAMAM were obtained. The CdTe QDs showed a high quantum yield (QY) up to 58%. By preparing CdTe QDs within HPAMAM, the biocompatibility properties of HPAMAM and the optical, electrical properties of CdTe QDs can be combined, endowing the CdTe QDs with biocompatibility. The resulting CdTe QDs can be directly used in biomedical fields, and their potential application in bio-imaging was investigated. PMID:24624925

  10. Highly Electrically Conductive Nanocomposites Based on PolymerInfused Graphene Sponges

    PubMed Central

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

    2014-01-01

    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

  11. Highly Transparent Conducting Polymer Top Contacts for Future III-Nitride Based Single Photon Emitters

    NASA Astrophysics Data System (ADS)

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

    2013-08-01

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

  12. Highly Conductive Anion-Exchange Membranes from Microporous Tröger's Base Polymers.

    PubMed

    Yang, Zhengjin; Guo, Rui; Malpass-Evans, Richard; Carta, Mariolino; McKeown, Neil B; Guiver, Michael D; Wu, Liang; Xu, Tongwen

    2016-09-12

    The development of polymeric anion-exchange membranes (AEMs) combining high ion conductivity and long-term stability is a major challenge for materials chemistry. AEMs with regularly distributed fixed cationic groups, based on the formation of microporous polymers containing the V-shape rigid Tröger's base units, are reported for the first time. Despite their simple preparation, which involves only two synthetic steps using commercially available precursors, the polymers provide AEMs with exceptional hydroxide conductivity at relatively low ion-exchange capacity, as well as a high swelling resistance and chemical stability. An unprecedented hydroxide conductivity of 164.4 mS cm(-1) is obtained at a relatively a low ion-exchange capacity of 0.82 mmol g(-1) under optimal operating conditions. The exceptional anion conductivity appears related to the intrinsic microporosity of the charged polymer matrix, which facilitates rapid anion transport. PMID:27505421

  13. Modified shape memory cyanate polymers with a wide range of high glass transition temperatures

    NASA Astrophysics Data System (ADS)

    Xie, Fang; Huang, Longnan; Liu, Yanju; Leng, Jinsong

    2012-04-01

    Shape memory cyanate polymers (SMCPs) are a new kind of smart materials, which have huge development potential and a promising future. A series of shape memory cyanate polymers were prepared by cyanate ester and varying content of a linear modifier. The thermal properties of the SMCPs were investigated by Differential Scanning Calorimetry (DSC), Thermal Gravimetric Analysis (TGA) and Dynamic Mechanical Analysis (DMA). The SMCPs we prepared have high glass transition temperature and show good heat resistance. The glass transition temperature Tg can be adjusted from 156.9°C to 259.6°C with the modifier. The initial temperature of thermal decomposition comes up to 300°C, which is enough high for the application in aerospace fields. The shape memory polymer we prepared shows a good shape memory effect, as the shape recovery time is less than 65s and the shape recovery rate reaches 95%.

  14. A Preliminary Study on the Toxic Combustion Products Testing of Polymers Used in High-Pressure Oxygen Systems

    NASA Technical Reports Server (NTRS)

    Hshieh, Fu-Yu; Beeson, Harold D.

    2004-01-01

    One likely cause of polymer ignition in a high-pressure oxygen system is adiabatic-compression heating of polymers caused by pneumatic impact. Oxidative _ pyrolysis or combustion of polymers in a high-pressure oxygen system could generate toxic gases. This paper reports the preliminary results of toxic combustion product testing of selected polymers in a pneumatic-impact test system. Five polymers commonly used in high-pressure oxygen systems, Nylon 6/6, polychlorotrifluoroethylene (CTFE), polytetrafluoroethylene (PTFE), fluoroelastomer (Viton(TradeMark) A), and nitrile rubber (Buna N), were tested in a pneumatic-impact test system at 2500- or 3500-psia oxygen pressure. The polymers were ignited and burned, then combustion products were collected in a stainless-steel sample bottle and analyzed by GC/MS/IRD, GC/FID, and GC/Methanizer/FID. The results of adiabatic-compression tests show that combustion of hydrocarbon polymers, nitrogen-containing polymers, and halogenated polymers in high-pressure oxygen systems are relatively complete. Toxicity of the combustion product gas is presumably much lower than the combustion product gas generated from ambient-pressure oxygen (or air) environments. The NASA-Lewis equilibrium code was used to determine the composition of combustion product gas generated from a simulated, adiabatic-compression test of nine polymers. The results are presented and discussed.

  15. High-performance polymer semiconducting heterostructure devices by nitrene-mediated photocrosslinking of alkyl side chains.

    PubMed

    Png, Rui-Qi; Chia, Perq-Jon; Tang, Jie-Cong; Liu, Bo; Sivaramakrishnan, Sankaran; Zhou, Mi; Khong, Siong-Hee; Chan, Hardy S O; Burroughes, Jeremy H; Chua, Lay-Lay; Friend, Richard H; Ho, Peter K H

    2010-02-01

    Heterostructures are central to the efficient manipulation of charge carriers, excitons and photons for high-performance semiconductor devices. Although these can be formed by stepwise evaporation of molecular semiconductors, they are a considerable challenge for polymers owing to re-dissolution of the underlying layers. Here we demonstrate a simple and versatile photocrosslinking methodology based on sterically hindered bis(fluorophenyl azide)s. The photocrosslinking efficiency is high and dominated by alkyl side-chain insertion reactions, which do not degrade semiconductor properties. We demonstrate two new back-infiltrated and contiguous interpenetrating donor-acceptor heterostructures for photovoltaic applications that inherently overcome internal recombination losses by ensuring path continuity to give high carrier-collection efficiency. This provides the appropriate morphology for high-efficiency polymer-based photovoltaics. We also demonstrate photopatternable polymer-based field-effect transistors and light-emitting diodes, and highly efficient separate-confinement-heterostructure light-emitting diodes. These results open the way to the general development of high-performance polymer semiconductor heterostructures that have not previously been thought possible. PMID:19966791

  16. Plasmon enhancement of luminescence upconversion.

    PubMed

    Park, Wounjhang; Lu, Dawei; Ahn, Sungmo

    2015-05-21

    Frequency conversion has always been an important topic in optics. Nonlinear optics has traditionally focused on frequency conversion based on nonlinear susceptibility but with the recent development of upconversion nanomaterials, luminescence upconversion has begun to receive renewed attention. While upconversion nanomaterials open doors to a wide range of new opportunities, they remain too inefficient for most applications. Incorporating plasmonic nanostructures provides a promising pathway to highly efficient upconversion. Naturally, a plethora of theoretical and experimental studies have been published in recent years, reporting enhancements up to several hundred. It is however difficult to make meaningful comparisons since the plasmonic fields are highly sensitive to the local geometry and excitation condition. Also, many luminescence upconversion processes involve multiple steps via different physical mechanisms and the overall output is often determined by a delicate interplay among them. This review is aimed at offering a comprehensive framework for plasmon enhanced luminescence upconversion. We first present quantum electrodynamics descriptions for all the processes involved in luminescence upconversion, which include absorption, emission, energy transfer and nonradiative transitions. We then present a bird's eye view of published works on plasmon enhanced upconversion, followed by more detailed discussion on comparable classes of nanostructures, the effects of spacer layers and local heating, and the dynamics of the plasmon enhanced upconversion process. Plasmon enhanced upconversion is a challenging and exciting field from the fundamental scientific perspective and also from technological standpoints. It offers an excellent system to study how optical processes are affected by the local photonic environment. This type of research is particularly timely as the plasmonics is placing heavier emphasis on nonlinearity. At the same time, efficient upconversion

  17. Investigations of non-linear polymers as high performance lubricant additives

    SciTech Connect

    Robinson, Joshua W.; Bhattacharya, Priyanka; Qu, Jun; Bays, J. Timothy; Cosimbescu, Lelia

    2015-03-22

    Off-the-shelf available engine oils contain an assortment of additives that increase the performance of base oils and maximize the overall efficiency of the machine. With ever increasing requirements for fuel efficiency, the demand for novel materials that outperform older generations is also on the rise. One approach towards increasing overall efficiency is to reduce internal friction and wear in an engine. From an additive approach, this is typically achieved by altering the bulk oil’s viscosity at high temperatures via polymers. In general, the hydrodynamic volume of polymers increase (expand) at elevated temperatures and decrease (contract/deflate) with declining temperatures and this effect is enhanced be carefully designing specific structures and architectures. The natural thinning tendency of base oil with increasing temperatures is in part mitigated by the expansion of the macromolecules added, and the overall effect is decreasing the viscosity losses at high temperatures. Traditional polymer architectures vary from linear to dendritic, where linear polymers of the same chemical composition and molecular weight to its dendritic counterpart will undergo a more significant free volume change in solution with regards to temperature changes. This advantage has been exploited in the literature towards the production of viscosity modifiers. However, one major disadvantage of linear polymers is degradation due to mechanical shear forces and high temperatures causing a shorter additive lifetime. Dendrimers on the other hand are known to demonstrate superior robustness to shear degradation when compared to their respective linear counterparts. An additional advantage of the dendritic architecture is the ability to tailor the peripheral end-groups towards influencing polymer-solvent and/or polymer-surface interactions. Comb-burst hyperbranched polymers are a hybrid of the aforementioned architectures and provide several compromises between the traditional

  18. Investigation of polymer derived ceramics cantilevers for application of high speed atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Wu, Chia-Yun

    High speed Atomic Force Microscopy (AFM) has a wide variety of applications ranging from nanomanufacturing to biophysics. In order to have higher scanning speed of certain AFM modes, high resonant frequency cantilevers are needed; therefore, the goal of this research is to investigate using polymer derived ceramics for possible applications in making high resonant frequency AFM cantilevers using complex cross sections. The polymer derived ceramic that will be studied, is silicon carbide. Polymer derived ceramics offer a potentially more economic fabrication approach for MEMS due to their relatively low processing temperatures and ease of complex shape design. Photolithography was used to make the desired cantilever shapes with micron scale size followed by a wet etching process to release the cantilevers from the substrates. The whole manufacturing process we use borrow well-developed techniques from the semiconducting industry, and as such this project also could offer the opportunity to reduce the fabrication cost of AFM cantilevers and MEMS in general. The characteristics of silicon carbide made from the precursor polymer, SMP-10 (Starfire Systems), were studied. In order to produce high qualities of silicon carbide cantilevers, where the major concern is defects, proper process parameters needed to be determined. Films of polymer derived ceramics often have defects due to shrinkage during the conversion process. Thus control of defects was a central issue in this study. A second, related concern was preventing oxidation; the polymer derived ceramics we chose is easily oxidized during processing. Establishing an environment without oxygen in the whole process was a significant challenge in the project. The optimization of the parameters for using photolithography and wet etching process was the final and central goal of the project; well established techniques used in microfabrication were modified for use in making the cantilever in the project. The techniques

  19. Clothing polymer fibers with well-aligned and high-aspect ratio carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Sun, Gengzhi; Zheng, Lianxi; An, Jia; Pan, Yongzheng; Zhou, Jinyuan; Zhan, Zhaoyao; Pang, John H. L.; Chua, Chee Kai; Leong, Kah Fai; Li, Lin

    2013-03-01

    It is believed that the crucial step towards preparation of electrical conductive polymer-carbon nanotube (CNT) composites is dispersing CNTs with a high length-to-diameter aspect ratio in a well-aligned manner. However, this process is extremely challenging when dealing with long and entangled CNTs. Here in this study, a new approach is demonstrated to fabricate conductive polymer-CNT composite fibers without involving any dispersion process. Well-aligned CNT films were firstly drawn from CNT arrays, and then directly coated on polycaprolactone fibers to form polymer-CNT composite fibers. The conductivity of these composite fibers can be as high as 285 S m-1 with only 2.5 wt% CNT loading, and reach 1549 S m-1 when CNT loading is 13.4 wt%. As-prepared composite fibers also exhibit 82% retention of conductivity at a strain of 7%, and have improved mechanical properties.It is believed that the crucial step towards preparation of electrical conductive polymer-carbon nanotube (CNT) composites is dispersing CNTs with a high length-to-diameter aspect ratio in a well-aligned manner. However, this process is extremely challenging when dealing with long and entangled CNTs. Here in this study, a new approach is demonstrated to fabricate conductive polymer-CNT composite fibers without involving any dispersion process. Well-aligned CNT films were firstly drawn from CNT arrays, and then directly coated on polycaprolactone fibers to form polymer-CNT composite fibers. The conductivity of these composite fibers can be as high as 285 S m-1 with only 2.5 wt% CNT loading, and reach 1549 S m-1 when CNT loading is 13.4 wt%. As-prepared composite fibers also exhibit 82% retention of conductivity at a strain of 7%, and have improved mechanical properties. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr34208e

  20. Ga(3+)/Ln(3+) Metallacrowns: A Promising Family of Highly Luminescent Lanthanide Complexes That Covers Visible and Near-Infrared Domains.

    PubMed

    Chow, Chun Y; Eliseeva, Svetlana V; Trivedi, Evan R; Nguyen, Tu N; Kampf, Jeff W; Petoud, Stéphane; Pecoraro, Vincent L

    2016-04-20

    visible (Sm, Eu, Tb, Dy, Tm). All Ln-1 complexes possess very high quantum yield values with respect to other literature compounds, indicating a good sensitization efficiency of the [12-MCGa(III)shi-4] scaffold. Especially, as of today, the Yb-1 complex exhibits the highest NIR quantum yield reported for a lanthanide(III) complex containing C-H bonds with a value of 5.88(2)% in the solid state. This work is a significant step forward toward versatile, easily prepared luminescent lanthanide(III) complexes suitable for a variety of applications including highly in demand biological imaging, especially in the NIR domain. PMID:27015360