High-performance polymer photovoltaic cells and photodetectors

NASA Astrophysics Data System (ADS)

Yu, Gang; Srdanov, Gordana; Wang, Hailiang; Cao, Yong; Heeger, Alan J.

2001-02-01

Polymer photovoltaic cells and photodetectors have passed their infancy and become mature technologies. The energy conversion efficiency of polymer photovoltaic cells have been improved to over 4.1% (500 nm, 10 mW/cm2). Such high efficiency polymer photovoltaic cells are promising for many applications including e-papers, e-books and smart- windows. The development of polymer photodetectors is even faster. The performance parameters have been improved to the level meeting all specifications for practical applications. The polymer photodetectors are of high photosensitivity (approximately 0.2 - 0.3 A/Watt in visible and UV), low dark current (0.1 - 1 nA/cm2), large dynamic range (> 8 orders of magnitude), linear intensity dependence, low noise level and fast response time (to nanosecond time domain). These devices show long shelf and operation lives. The advantages of low manufacturing cost, large detection area, and easy hybridization and integration with other electronic or optical components make the polymer photodetectors promising for a variety of applications including chemical/biomedical analysis, full-color digital image sensing and high energy radiation detection.

Alkaline earth-based coordination polymers derived from a cyclotriphosphazene-functionalized hexacarboxylate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ling, Yajing; Bai, Dongjie; Feng, Yunlong

Combination of hexakis(4-carboxylatephenoxy)cyclotriphosphazene with alkaline earth ions of increasing ionic radii (Mg{sup 2+}, Ca{sup 2+} and Ba{sup 2+}) under different solvothermal conditions yielded three new coordination polymers, and their crystal structures were determined by single-crystal X-ray diffraction analysis. The magnesium compound displays a three dimensional (3D) network structure constructed from the deprotonated ligand and the secondary building block Mg(COO){sub 4}, which can be rationalized as a (4,6)-connected topological net with the Schläfli symbol of (4{sup 4}·6{sup 2}){sub 3}(4{sup 9}·6{sup 6}){sub 2}. The calcium compound consists of 1D infinite “Ca-O” inorganic chains connected by the deprotonated ligands to from a 3Dmore » framework. The barium compound exhibits a 3D framework in which 1D “Ba-O” inorganic chains are connected together by the deprotonated organic linkers. Due to the semi-rigid nature, the ligand adopts distinctly different conformations in the three compounds. The metal ions’ influence exerted on the final structure of the resulting coordination polymers is also discussed. When the radii of alkaline earth ions increases descending down the group from Mg(II) to Ba(II), the coordination number becomes larger and more versatile: from 6 in the magnesium compound, to 6,7 and 10 in the calcium compound, and to 8 and 9 in the barium compound, thus substantially influencing the resulting final framework structures. Also, the photophysical properties were investigated systematically, revealing that the three compounds are photoluminscent in the solid state at room temperature. This work demonstrates that although the multiplicity of conformation in the hexacarboxylate ligand based on the inorganic scaffold cyclotriphosphazene makes it difficult to predict how this ligand will form extended network, but provides unique opportunities for the formation of diverse inorganic-organic hybrids exhibiting rich structural

Novel inorganic materials for polymer electrolyte and alkaline fuel cells

NASA Astrophysics Data System (ADS)

Tadanaga, Kiyoharu

2012-06-01

Inorganic materials with high ionic conductivity must have big advantages for the thermal and long term stability when the materials are used as the electrolyte of fuel cells. In the present paper, novel ionic conductive inorganic materials for polymer electrolyte fuel cells (PEFCs) and all solid state alkaline fuel cells (AFCs) that have been developed by our group have been reviewed. PEFCs which can operate in temperature range from 100 to 200 °C are intensively studied because of some advantages such as reduction of CO poisoning of Pt catalyst and acceleration of electrode reactions. We showed that the fuel cells using the composite membranes prepared from phosphosilicate gel powder and polyimide precursor can operate in the temperature range from 30 to 180 °C. We also found that the inorganic-organic hybrid membranes with acid-base pairs from 3-aminopropyl triethoxy silane and H2SO4 or H3PO4 show high proton conductivity under dry atmosphere, and the membranes are thermally stable at intermediate temperatures. On the other hand, because the use of noble platinum is the serious problem for the commercialization of PEFCs and because oxidation reactions are usually faster than those of acid-type fuel cells, alkaline type fuel cells, in which a nonplatinum catalyst can be used, are attractive. Recently, we have proposed an alkaline-type direct ethanol fuel cell (DEFC) using a natural clay electrolyte with non-platinum catalysts. So-called hydrotalcite clay, Mg-Al layered double hydroxide intercalated with CO32- (Mg-Al CO32- LDH), has been proved to be a hydroxide ion conductor. An alkalinetype DEFC using Mg-Al CO32- LDH as the electrolyte and aqueous solution of ethanol and potassium hydroxide as a source of fuel exhibited excellent electrochemical performance.

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.

Chlorination of low-band-gap polymers: Toward high-performance polymer solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mo, Daize; Wang, Huan; Chen, Hui

Here, halogenation is an effective way to tune the energy levels of organic semiconducting materials. To date, fluorination of organic semiconducting materials to fabricate polymer solar cells (PSCs) has been used far more than chlorination; however, fluorine exchange reactions suffer from low yields and the resulting fluorinated polymer always comes with higher price, which will greatly hinder their commercial applications. Herein, we designed and synthesized a series of chlorinated donor-acceptor (D-A) type polymers, in which benzo[1,2-b:4,5- b]dithiophene and chlorinated benzothiadiazole units are connected by thiophene π-bridges with an asymmetric alkyl chain. These chlorinated polymers showed deep highest occupied molecular orbitalmore » energy levels, which promoted the efficiency of their corresponding PSCs by increasing the device open circuit voltage. The asymmetric alkyl chain on the thiophene moieties gave the final polymer sufficient solubility for solution processing and strong π-π stacking in films allowed for high mobility. Although the introduction of a large chlorine atom increased the torsion angle of the polymer backbone, the chlorinated polymers maintained high crystallinity and a favorable backbone orientation in the blended films. These factors contributed to respectable device performances from thick-film devices, which showed PCEs as high as 9.11% for a 250 nm-thick active layer. These results demonstrate that chlorination is a promising method to fine tune the energy levels of conjugated polymers, and chlorinated benzothiadiazole may be a versatile building block in materials for efficient solar energy conversion.« less

Chlorination of low-band-gap polymers: Toward high-performance polymer solar cells

DOE PAGES

Mo, Daize; Wang, Huan; Chen, Hui; ...

2017-03-08

Here, halogenation is an effective way to tune the energy levels of organic semiconducting materials. To date, fluorination of organic semiconducting materials to fabricate polymer solar cells (PSCs) has been used far more than chlorination; however, fluorine exchange reactions suffer from low yields and the resulting fluorinated polymer always comes with higher price, which will greatly hinder their commercial applications. Herein, we designed and synthesized a series of chlorinated donor-acceptor (D-A) type polymers, in which benzo[1,2-b:4,5- b]dithiophene and chlorinated benzothiadiazole units are connected by thiophene π-bridges with an asymmetric alkyl chain. These chlorinated polymers showed deep highest occupied molecular orbitalmore » energy levels, which promoted the efficiency of their corresponding PSCs by increasing the device open circuit voltage. The asymmetric alkyl chain on the thiophene moieties gave the final polymer sufficient solubility for solution processing and strong π-π stacking in films allowed for high mobility. Although the introduction of a large chlorine atom increased the torsion angle of the polymer backbone, the chlorinated polymers maintained high crystallinity and a favorable backbone orientation in the blended films. These factors contributed to respectable device performances from thick-film devices, which showed PCEs as high as 9.11% for a 250 nm-thick active layer. These results demonstrate that chlorination is a promising method to fine tune the energy levels of conjugated polymers, and chlorinated benzothiadiazole may be a versatile building block in materials for efficient solar energy conversion.« less

High Performance Tandem Perovskite/Polymer Solar Cells

NASA Astrophysics Data System (ADS)

Liu, Yao; Bag, Monojit; Page, Zachariah; Renna, Lawrence; Kim, Paul; Choi, Jaewon; Emrick, Todd; Venkataraman, D.; Russell, Thomas

Combining perovskites with other inorganic materials, such as copper indium gallium diselenide (CIGS) or silicon, is enabling significant improvement in solar cell device performance. Here, we demonstrate a highly efficient hybrid tandem solar cell fabricated through a facile solution deposition approach to give a perovskite front sub-cell and a polymer:fullerene blend back sub-cell. This methodology eliminates the adverse effects of thermal annealing during perovskite fabrication on polymer solar cells. The record tandem solar cell efficiency of 15.96% is 40% greater than the corresponding perovskite-based single junction device and 65% greater than the polymer-based single junction device, while mitigating deleterious hysteresis effects often associated with perovskite solar cells. The hybrid tandem devices demonstrate the synergistic effects arising from the combination of perovskite and polymer-based materials for solar cells. This work was supported by the Department of Energy-supported Energy Frontier Research Center at the University of Massachusetts (DE-SC0001087). The authors acknowledge the W.M. Keck Electron Microscopy.

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

Toward High Performance Photovoltaic Cells based on Conjugated Polymers

DTIC Science & Technology

2016-12-26

AFRL-AFOSR-JP-TR-2016-0103 Toward High Performance Photovoltaic Cells based on Conjugated Polymers Kung-Hwa Wei National Chiao Tung University Final...Conjugated Polymers 5a.  CONTRACT NUMBER 5b.  GRANT NUMBER FA2386-15-1-4113 5c.  PROGRAM ELEMENT NUMBER 61102F 6. AUTHOR(S) Kung-Hwa Wei 5d.  PROJECT...gap polymer with good packing order as the active layer for a single-junction photovoltaic device. The light absorptions for the small molecule and the

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

2016-06-08

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.

Achieving high performance polymer tandem solar cells via novel materials design

NASA Astrophysics Data System (ADS)

Dou, Letian

Organic photovoltaic (OPV) devices show great promise in low-cost, flexible, lightweight, and large-area energy-generation applications. Nonetheless, most of the materials designed today always suffer from the inherent disadvantage of not having a broad absorption range, and relatively low mobility, which limit the utilization of the full solar spectrum. Tandem solar cells provide an effective way to harvest a broader spectrum of solar radiation by combining two or more solar cells with different absorption bands. However, for polymer solar cells, the performance of tandem devices lags behind single-layer solar cells mainly due to the lack of suitable low-bandgap polymers (near-IR absorbing polymers). In this dissertation, in order to achieve high performance, we focus on design and synthesis of novel low bandgap polymers specifically for tandem solar cells. In Chapter 3, I demonstrate highly efficient single junction and tandem polymer solar cells featuring a spectrally matched low-bandgap conjugated polymer (PBDTT-DPP: bandgap, ˜1.44 eV). The polymer has a backbone based on alternating benzodithiophene and diketopyrrolopyrrole units. A single-layer device based on the polymer provides a power conversion efficiency of ˜6%. When the polymer is applied to tandem solar cells, a power conversion efficiency of 8.62% is achieved, which was the highest certified efficiency for a polymer solar cell. To further improve this material system, in Chapter 4, I show that the reduction of the bandgap and the enhancement of the charge transport properties of the low bandgap polymer PBDTT-DPP can be accomplished simultaneously by substituting the sulfur atoms on the DPP unit with selenium atoms. The newly designed polymer PBDTT-SeDPP (Eg = 1.38 eV) shows excellent photovoltaic performance in single junction devices with PCEs over 7% and photo-response up to 900 nm. Tandem polymer solar cells based on PBDTT-SeDPP are also demonstrated with a 9.5% PCE, which are more than 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

Conducting polymer nanowire arrays for high performance supercapacitors.

PubMed

Wang, Kai; Wu, Haiping; Meng, Yuena; Wei, Zhixiang

2014-01-15

This Review provides a brief summary of the most recent research developments in the fabrication and application of one-dimensional ordered conducting polymers nanostructure (especially nanowire arrays) and their composites as electrodes for supercapacitors. By controlling the nucleation and growth process of polymerization, aligned conducting polymer nanowire arrays and their composites with nano-carbon materials can be prepared by employing in situ chemical polymerization or electrochemical polymerization without a template. This kind of nanostructure (such as polypyrrole and polyaniline nanowire arrays) possesses high capacitance, superior rate capability ascribed to large electrochemical surface, and an optimal ion diffusion path in the ordered nanowire structure, which is proved to be an ideal electrode material for high performance supercapacitors. Furthermore, flexible, micro-scale, threadlike, and multifunctional supercapacitors are introduced based on conducting polyaniline nanowire arrays and their composites. These prototypes of supercapacitors utilize the high flexibility, good processability, and large capacitance of conducting polymers, which efficiently extend the usage of supercapacitors in various situations, and even for a complicated integration system of different electronic devices. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dye-Incorporated Polynaphthalenediimide Acceptor for Additive-Free High-Performance All-Polymer Solar Cells.

PubMed

Chen, Dong; Yao, Jia; Chen, Lie; Yin, Jingping; Lv, Ruizhi; Huang, Bin; Liu, Siqi; Zhang, Zhi-Guo; Yang, Chunhe; Chen, Yiwang; Li, Yongfang

2018-04-16

All-polymer solar cells (all-PSCs) can offer unique advantages for applications in flexible devices, and naphthalene diimide (NDI)-based polymer acceptors are the widely used polymer acceptors. However, their power conversion efficiency (PCE) still lags behind that of state-of-the-art polymer solar cells, due to low light absorption, suboptimal energy levels and the strong aggregation of the NDI-based polymer acceptor. Herein, a rhodanine-based dye molecule was introduced into the NDI-based polymer acceptor by simple random copolymerization and showed an improved light absorption coefficient, an up-shifted lowest unoccupied molecular orbital level and reduced crystallization. Consequently, additive-free all-PSCs demonstrated a high PCE of 8.13 %, which is one of the highest performance characteristics reported for all-PSCs to date. These results indicate that incorporating a dye into the n-type polymer gives insight into the precise design of high-performance polymer acceptors for all-PSCs. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

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.

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

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

High-performance oxygen reduction catalysts in both alkaline and acidic fuel cells based on pre-treating carbon material and iron precursor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Song, Ping; Barkholtz, Heather M.; Wang, Ying

We demonstrate a new and simple method for pre-treating the carbon material and iron precursor to prepare oxygen reduction reaction (ORR) catalysts, which can produce super-high performance and stability in alkaline solution, with high performance in acid solution. This strategy using cheap materials is simply controllable. Moreover, it has achieved smaller uniform nanoparticles to exhibit high stability, and the synergetic effect of Fe and N offered much higher performance in ORR than commercial Pt/C, with high maximum power density in alkaline and acid fuel cell test. So it can make this kind of catalysts be the most promising alternatives ofmore » Pt-based catalysts with best performance/price.« less

High performance optical materials cyclo olefin polymer ZEONEX

NASA Astrophysics Data System (ADS)

Obuchi, Kazuyuki; Komatsu, Masaaki; Minami, Koji

2007-09-01

ZEON CORPORATION developed innovative optical plastic Cyclo Olefin Polymer (COP), ZEONEX (R) with own technology in 1990 then started commercial production of ZEONEX (R) for optical applications with its very unique properties such as high light transmission, low birefringence, low water absorption, and high glass-transition temperature etc. ZEONEX (R) exhibits outstanding optical performance even under high humidity and temperature conditions. In order to meet increasing requirements of optical market, ZEON CORPORATION newly developed ZEONEX (R)F52R which has high glass-transition temperature 156 deg. C and shows the feature of very low focal length change after high-temperature and high-humidity test.

Recyclable Cu(II)-Coordination Crosslinked Poly(benzimidazolyl pyridine)s as High-Performance Polymers.

PubMed

Wang, Cheng; Yang, Li; Chang, Guanjun

2018-03-01

Crosslinked high-performance polymers have many industrial applications, but are difficult to recycle or rework. A novel class of recyclable crosslinking Cu(II)-metallo-supramolecular coordination polymers are successfully prepared, which possess outstanding thermal stability and mechanical property. More importantly, the Cu 2+ coordination interactions can be further removed via external pyrophosphate to recover the linear polymers, which endow the crosslinking polymers with recyclability. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Quickly updatable hologram images with high performance photorefractive polymer composites

NASA Astrophysics Data System (ADS)

Tsutsumi, Naoto; Kinashi, Kenji; Nonomura, Asato; Sakai, Wataru

2012-02-01

We present here quickly updatable hologram images using high performance photorefractive (PR) polymer composite based on poly(N-vinyl carbazole) (PVCz). PVCz is one of the pioneer materials for photoconductive polymer. PVCz/7- DCST/CzEPA/TNF (44/35/20/1 by wt) gives high diffraction efficiency of 68 % at E = 45 V/μm with fast response speed. Response speed of optical diffraction is the key parameter for real-time 3D holographic display. Key parameter for obtaining quickly updatable hologram images is to control the glass transition temperature lower enough to enhance chromophore orientation. Object image of the reflected coin surface recorded with reference beam at 532 nm (green beam) in the PR polymer composite is simultaneously reconstructed using a red probe beam at 642 nm. Instead of using coin object, object image produced by a computer was displayed on a spatial light modulator (SLM) is used as an object for hologram. Reflected object beam from a SLM interfered with reference beam on PR polymer composite to record a hologram and simultaneously reconstructed by a red probe beam. Movie produced in a computer was recorded as a realtime hologram in the PR polymer composite and simultaneously clearly reconstructed with a video rate.

Alternative High Performance Polymers for Ablative Thermal Protection Systems

NASA Technical Reports Server (NTRS)

Boghozian, Tane; Stackpoole, Mairead; Gonzales, Greg

2015-01-01

Ablative thermal protection systems are commonly used as protection from the intense heat during re-entry of a space vehicle and have been used successfully on many missions including Stardust and Mars Science Laboratory both of which used PICA - a phenolic based ablator. Historically, phenolic resin has served as the ablative polymer for many TPS systems. However, it has limitations in both processing and properties such as char yield, glass transition temperature and char stability. Therefore alternative high performance polymers are being considered including cyanate ester resin, polyimide, and polybenzoxazine. Thermal and mechanical properties of these resin systems were characterized and compared with phenolic resin.

Tailor-Made Electrospun Multilayer Composite Polymer Electrolytes for High-Performance Lithium Polymer Batteries.

PubMed

Lim, Du-Hyun; Haridas, Anupriya K; Figerez, Stelbin Peter; Raghavan, Prasanth; Matic, Aleksandar; Ahn, Jou-Hyeon

2018-09-01

A novel tailor-made multilayer composite polymer electrolyte, consisting of two outer layers of electrospun polyacrylonitrile (PAN) and one inner layer of poly(vinyl acetate) (PVAc)/poly(methyl methacrylate) (PMMA)/poly(ethylene oxide) (PEO) fibrous membrane, was prepared using continuous electrospinning. These membranes, which are made up of fibers with diameters in the nanometer range, were stacked in layers to produce interconnected pores that result in a high porosity. Gel polymer electrolytes (GPEs) were prepared by entrapping a liquid electrolyte (1 M LiPF6 in ethylene carbonate/dimethyl carbonate) in the membranes. The composite membranes exhibited a high electrolyte uptake of 450-510%, coupled with an improved room temperature ionic conductivity of up to 4.72 mS cm-1 and a high electrochemical stability of 4.6 V versus Li/Li+. Electrochemical investigations of a composite membrane of PAN-PVAc-PAN, with a LiFePO4 cathode synthesized in-house, showed a high initial discharge capacity of 145 mAh g-1, which corresponds to 85% utilization of the active material, and displayed stable cycle performance.

High-Performance All-Polymer Solar Cells Achieved by Fused Perylenediimide-Based Conjugated Polymer Acceptors.

PubMed

Yin, Yuli; Yang, Jing; Guo, Fengyun; Zhou, Erjun; Zhao, Liancheng; Zhang, Yong

2018-05-09

We report three n-type polymeric electron acceptors (PFPDI-TT, PFPDI-T, and PFPDI-Se) based on the fused perylene diimide (FPDI) and thieno[3,2- b]thiophene, thiophene, or selenophene units for all-polymer solar cells (all-PSCs). These FPDI-based polymer acceptors exhibit strong absorption between 350 and 650 nm with wide optical bandgap of 1.86-1.91 eV, showing good absorption compensation with the narrow bandgap polymer donor. The lowest unoccupied molecular orbital (LUMO) energy levels were located at around -4.11 eV, which are comparable with those of the fullerene derivatives and other small molecular electron acceptors. The conventional all-PSCs based on the three polymer acceptors and PTB7-Th as polymer donor gave remarkable power conversion efficiencies (PCEs) of >6%, and the PFPDI-Se-based all-PSC achieved the highest PCE of 6.58% with a short-circuit current density ( J sc ) of 13.96 mA/cm 2 , an open-circuit voltage ( V oc ) of 0.76 V, and a fill factor (FF) of 62.0%. More interestingly, our results indicate that the photovoltaic performances of the FPDI-based polymer acceptors are mainly determined by the FPDI unit with a small effect from the comonomers, which is quite different from the others reported rylenediimide-based polymer acceptors. This intriguing phenomenon is speculated as the huge geometry configuration of the FPDI unit, which minimizes the effect of the comonomer. These results highlight a promising future for the application of the FPDI-based polymer acceptors in the highly efficient all-PSCs.

Probing the electrochemical properties of biopolymer modified EMD nanoflakes through electrodeposition for high performance alkaline batteries.

PubMed

Biswal, Avijit; Minakshi, Manickam; Tripathy, Bankim Chandra

2016-04-07

In the present work, a novel biopolymer approach has been made to electrodeposit manganese dioxide from manganese sulphate in a sulphuric acid bath containing chitosan in the absence and presence of glutaraldehyde as a cross-linking agent. Galvanostatically synthesised electrolytic manganese dioxide (EMD) nanoflakes were used as electrode materials and their electrochemical properties with the influence of biopolymer chitosan were systematically characterized. The structural determination, surface morphology and porosity of nanostructured EMD were evaluated using X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy and nitrogen adsorption-desorption techniques. The results obtained were compared with that of blank EMD (polymer free). The results indicated that the EMD having chitosan cross-linked with glutaraldehyde possesses a reduced particle size and more porous structure than the blank and EMDs synthesized in the presence of chitosan but without glutaraldehyde. The results revealed that chitosan was unable to play any significant role on its own but chitosan in the presence of glutaraldehyde forms a cross-linking structure, which in turn influences the nucleation and growth of the EMDs during electrodeposition. EMDs obtained in the presence of chitosan (1 g dm(-3)) and glutaraldehyde (1% glutaraldehyde) exhibited a reversible and better discharge capacity upon cycling than the blank which showed its typical capacity fading behaviour with cycling. In addition, EMD synthesized in the presence of 1 g dm(-3) chitosan and 2% glutaraldehyde exhibited a superior electrochemical performance than the blank and lower amounts (1%; 1.5%) of glutaraldehyde, showing a stable discharge capacity of 60 mA h g(-1) recorded up to 40 cycles in alkaline KOH electrolyte for a Zn-MnO2 system. Our results demonstrate the potential of using polymer modified EMDs as a new generation of alkaline battery materials. The XPS data show that

Preparation and Characterization of PVA Alkaline Solid Polymer Electrolyte with Addition of Bamboo Charcoal.

PubMed

Fan, Lidan; Wang, Mengyue; Zhang, Zhen; Qin, Gang; Hu, Xiaoyi; Chen, Qiang

2018-04-26

Natural bamboo charcoal (BC) powder has been developed as a novel filler in order to further improve performances of the polyvinyl alcohol (PVA)-based alkaline solid polymer electrolyte (ASPE) by solution casting method. X-ray diffraction patterns of composite polymer electrolyte with BC revealed the decrease in the degree of crystallinity with increasing content of BC. Scanning electron microscopy images showed pores on a micrometer scale (average diameter about 2 μm) distributed inside and on the surface of the membranes, indicating a three-dimension network formed in the polymer framework. The ionic conductivity was measured by the alternating-current (AC) impedance method, and the highest conductivity value of 6.63 × 10 −2 S·cm −1 was obtained with 16 wt % of BC content and m KOH : m PVA = 2:1.5 at 30 °C. The contents of BC and KOH could significantly influence the conductivity. The temperature dependence of the bulk electrical conductivity displayed a combination of Arrhenius nature, and the activation energy for the ion in polymer electrolyte has been calculated. The electrochemical stability window of the electrolyte membrane was over 1.6 V. The thermogravimetric analysis curves showed that the degradation temperatures of PVA-BC-KOH ASPE membranes shifted toward higher with adding BC. A simple nickel-hydrogen battery containing PVA-BC-KOH electrolyte membrane was assembled with a maximum discharge capacity of 193 mAh·g −1 .

Ultra‐high performance supercritical fluid chromatography of lignin‐derived phenols from alkaline cupric oxide oxidation

PubMed Central

Sun, Mingzhe; Lidén, Gunnar; Sandahl, Margareta

2016-01-01

Traditional chromatographic methods for the analysis of lignin‐derived phenolic compounds in environmental samples are generally time consuming. In this work, an ultra‐high performance supercritical fluid chromatography method with a diode array detector for the analysis of major lignin‐derived phenolic compounds produced by alkaline cupric oxide oxidation was developed. In an analysis of a collection of 11 representative monomeric lignin phenolic compounds, all compounds were clearly separated within 6 min with excellent peak shapes, with a limit of detection of 0.5–2.5 μM, a limit of quantification of 2.5–5.0 μM, and a dynamic range of 5.0–2.0 mM (R 2 > 0.997). The new ultra‐high performance supercritical fluid chromatography method was also applied for the qualitative and quantitative analysis of lignin‐derived phenolic compounds obtained upon alkaline cupric oxide oxidation of a commercial humic acid. Ten out of the previous eleven model compounds could be quantified in the oxidized humic acid sample. The high separation power and short analysis time obtained demonstrate for the first time that supercritical fluid chromatography is a fast and reliable technique for the analysis of lignin‐derived phenols in complex environmental samples. PMID:27452148

Elucidating Performance Limitations in Alkaline-Exchange- Membrane Fuel Cells

DOE PAGES

Shiau, Huai-Suen; Zenyuk, Iryna V.; Weber, Adam Z.

2017-07-15

Water management is a serious concern for alkaline-exchange-membrane fuel cells (AEMFCs) because water is a reactant in the alkaline oxygen-reduction reaction and hydroxide conduction in alkaline-exchange membranes is highly hydration dependent. Here in this article, we develop and use a multiphysics, multiphase model to explore water management in AEMFCs. We demonstrate that the low performance is mostly caused by extremely non-uniform distribution of water in the ionomer phase. A sensitivity analysis of design parameters including humidification strategies, membrane properties, and water transport resistance was undertaken to explore possible optimization strategies. Furthermore, the strategy and issues of reducing bicarbonate/carbonate buildup inmore » the membrane-electrode assembly with CO 2 from air is demonstrated based on the model prediction. Overall, mathematical modeling is used to explore trends and strategies to overcome performance bottlenecks and help enable AEMFC commercialization.« less

Increased performance of hydrogen production in microbial electrolysis cells under alkaline conditions.

PubMed

Rago, Laura; Baeza, Juan A; Guisasola, Albert

2016-06-01

This work reports the first successful enrichment and operation of alkaline bioelectrochemical systems (microbial fuel cells, MFC, and microbial electrolysis cells, MEC). Alkaline (pH=9.3) bioelectrochemical hydrogen production presented better performance (+117%) compared to conventional neutral conditions (2.6 vs 1.2 litres of hydrogen gas per litre of reactor per day, LH2·L(-1)REACTOR·d(-1)). Pyrosequencing results of the anodic biofilm showed that while Geobacter was mainly detected under conventional neutral conditions, Geoalkalibacter sp. was highly detected in the alkaline MFC (21%) and MEC (48%). This is the first report of a high enrichment of Geoalkalibacter from an anaerobic mixed culture using alkaline conditions in an MEC. Moreover, Alkalibacter sp. was highly present in the anodic biofilm of the alkaline MFC (37%), which would indicate its potentiality as a new exoelectrogen. Copyright © 2016 Elsevier B.V. All rights reserved.

Multipositional silica-coated silver nanoparticles for high-performance polymer solar cells.

PubMed

Choi, Hyosung; Lee, Jung-Pil; Ko, Seo-Jin; Jung, Jae-Woo; Park, Hyungmin; Yoo, Seungmin; Park, Okji; Jeong, Jong-Ryul; Park, Soojin; Kim, Jin Young

2013-05-08

We demonstrate high-performance polymer solar cells using the plasmonic effect of multipositional silica-coated silver nanoparticles. The location of the nanoparticles is critical for increasing light absorption and scattering via enhanced electric field distribution. The device incorporating nanoparticles between the hole transport layer and the active layer achieves a power conversion efficiency of 8.92% with an external quantum efficiency of 81.5%. These device efficiencies are the highest values reported to date for plasmonic polymer solar cells using metal nanoparticles.

Fluorinated benzothiadiazole-based conjugated polymers for high-performance polymer solar cells without any processing additives or post-treatments.

PubMed

Wang, Ning; Chen, Zheng; Wei, Wei; Jiang, Zhenhua

2013-11-13

Thanks to their many favorable advantages, polymer solar cells exhibit great potential for next-generation clean energy sources. Herein, we have successfully designed and synthesized a series of new fluorinated benzothiadiazole-based conjugated copolymers PBDT(TEH)-DT(H)BTff (P1), PBDT(TEH)-DT(EH)BTff (P2), and PBDT(HDO)-DT(H)BTff (P3). The power conversion efficiencies of 4.46, 6.20, and 8.30% were achieved for P1-, P2-, and P3-based devices within ~100 nm thickness active layers under AM 1.5G illumination without any processing additives or post-treatments, respectively. The PCE of 8.30% for P3 is the highest value for the reported traditional single-junction polymer solar cells via a simple fabrication architecture without any additives or post-treatments. In addition, it is noteworthy that P3 also allows making high efficient polymer solar cells with high PCEs of 7.27 and 6.56% under the same condition for ~200 and ~300 nm thickness active layers, respectively. Excellent photoelectric properties and good solubility make polymer P3 become an alternative material for high-performance polymer solar cells.

High-Speed 3D Printing of High-Performance Thermosetting Polymers via Two-Stage Curing.

PubMed

Kuang, Xiao; Zhao, Zeang; Chen, Kaijuan; Fang, Daining; Kang, Guozheng; Qi, Hang Jerry

2018-04-01

Design and direct fabrication of high-performance thermosets and composites via 3D printing are highly desirable in engineering applications. Most 3D printed thermosetting polymers to date suffer from poor mechanical properties and low printing speed. Here, a novel ink for high-speed 3D printing of high-performance epoxy thermosets via a two-stage curing approach is presented. The ink containing photocurable resin and thermally curable epoxy resin is used for the digital light processing (DLP) 3D printing. After printing, the part is thermally cured at elevated temperature to yield an interpenetrating polymer network epoxy composite, whose mechanical properties are comparable to engineering epoxy. The printing speed is accelerated by the continuous liquid interface production assisted DLP 3D printing method, achieving a printing speed as high as 216 mm h -1 . It is also demonstrated that 3D printing structural electronics can be achieved by combining the 3D printed epoxy composites with infilled silver ink in the hollow channels. The new 3D printing method via two-stage curing combines the attributes of outstanding printing speed, high resolution, low volume shrinkage, and excellent mechanical properties, and provides a new avenue to fabricate 3D thermosetting composites with excellent mechanical properties and high efficiency toward high-performance and functional applications. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Graphene Oxide Derivatives as Hole- and Electron-Extraction Layers for High-Performance Polymer Solar Cells

DTIC Science & Technology

2013-11-20

Graphene oxide derivatives as hole- and electron- extraction layers for high-performance polymer solar cells Jun Liu,*a Michael Durstockb and Liming...oxide (GO) and its derivatives have been used as a new class of efficient hole- and electron-extraction materials in polymer solar cells (PSCs...new class of efficient hole- and electron-extraction materials in polymer solar cells (PSCs). Highly efficient and stable PSCs have been fabricated

A High-Performance Sintered Iron Electrode for Rechargeable Alkaline Batteries to Enable Large-Scale Energy Storage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Chenguang; Manohar, Aswin K.; Narayanan, S. R.

Iron-based alkaline rechargeable batteries such as iron-air and nickel-iron batteries are particularly attractive for large-scale energy storage because these batteries can be relatively inexpensive, environment- friendly, and also safe. Therefore, our study has focused on achieving the essential electrical performance and cycling properties needed for the widespread use of iron-based alkaline batteries in stationary and distributed energy storage applications.We have demonstrated for the first time, an advanced sintered iron electrode capable of 3500 cycles of repeated charge and discharge at the 1-hour rate and 100% depth of discharge in each cycle, and an average Coulombic efficiency of over 97%. Suchmore » a robust and efficient rechargeable iron electrode is also capable of continuous discharge at rates as high as 3C with no noticeable loss in utilization. We have shown that the porosity, pore size and thickness of the sintered electrode can be selected rationally to optimize specific capacity, rate capability and robustness. As a result, these advances in the electrical performance and durability of the iron electrode enables iron-based alkaline batteries to be a viable technology solution for meeting the dire need for large-scale electrical energy storage.« less

A High-Performance Sintered Iron Electrode for Rechargeable Alkaline Batteries to Enable Large-Scale Energy Storage

DOE PAGES

Yang, Chenguang; Manohar, Aswin K.; Narayanan, S. R.

2017-01-07

Iron-based alkaline rechargeable batteries such as iron-air and nickel-iron batteries are particularly attractive for large-scale energy storage because these batteries can be relatively inexpensive, environment- friendly, and also safe. Therefore, our study has focused on achieving the essential electrical performance and cycling properties needed for the widespread use of iron-based alkaline batteries in stationary and distributed energy storage applications.We have demonstrated for the first time, an advanced sintered iron electrode capable of 3500 cycles of repeated charge and discharge at the 1-hour rate and 100% depth of discharge in each cycle, and an average Coulombic efficiency of over 97%. Suchmore » a robust and efficient rechargeable iron electrode is also capable of continuous discharge at rates as high as 3C with no noticeable loss in utilization. We have shown that the porosity, pore size and thickness of the sintered electrode can be selected rationally to optimize specific capacity, rate capability and robustness. As a result, these advances in the electrical performance and durability of the iron electrode enables iron-based alkaline batteries to be a viable technology solution for meeting the dire need for large-scale electrical energy storage.« less

Ultra-high performance supercritical fluid chromatography of lignin-derived phenols from alkaline cupric oxide oxidation.

PubMed

Sun, Mingzhe; Lidén, Gunnar; Sandahl, Margareta; Turner, Charlotta

2016-08-01

Traditional chromatographic methods for the analysis of lignin-derived phenolic compounds in environmental samples are generally time consuming. In this work, an ultra-high performance supercritical fluid chromatography method with a diode array detector for the analysis of major lignin-derived phenolic compounds produced by alkaline cupric oxide oxidation was developed. In an analysis of a collection of 11 representative monomeric lignin phenolic compounds, all compounds were clearly separated within 6 min with excellent peak shapes, with a limit of detection of 0.5-2.5 μM, a limit of quantification of 2.5-5.0 μM, and a dynamic range of 5.0-2.0 mM (R(2) > 0.997). The new ultra-high performance supercritical fluid chromatography method was also applied for the qualitative and quantitative analysis of lignin-derived phenolic compounds obtained upon alkaline cupric oxide oxidation of a commercial humic acid. Ten out of the previous eleven model compounds could be quantified in the oxidized humic acid sample. The high separation power and short analysis time obtained demonstrate for the first time that supercritical fluid chromatography is a fast and reliable technique for the analysis of lignin-derived phenols in complex environmental samples. © 2016 The Authors, Journal of Separation Science Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

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.

Menstrual blood loss measurement: validation of the alkaline hematin technique for feminine hygiene products containing superabsorbent polymers.

PubMed

Magnay, Julia L; Nevatte, Tracy M; Dhingra, Vandana; O'Brien, Shaughn

2010-12-01

To validate the alkaline hematin technique for measurement of menstrual blood loss using ultra-thin sanitary towels that contain superabsorbent polymer granules as the absorptive agent. Laboratory study using simulated menstrual fluid (SMF) and Always Ultra Normal, Long, and Night "with wings" sanitary towels. Keele Menstrual Disorders Laboratory. None. None. Recovery of blood, linearity, and interassay variation over a range of SMF volumes applied to towels. Because of the variable percentage of blood in menstrual fluid, blood recovery was assessed from SMF constituted as 10%, 25%, 50%, and 100% blood. The lower limit of reliable detection and the effect of storing soiled towels for up to 4 weeks at 15°C-20°C, 4°C, and -20°C before analysis were determined. Ninety percent recovery was reproducibly achieved up to 30 mL applied volume at all tested SMF compositions, except at low volume or high dilution equivalent to <2 mL whole blood. Samples could be stored for 3 weeks at all tested temperatures without loss of recovery. The technique was suitable for processing towels individually or in batches. The alkaline hematin technique is a suitable and validated method for measuring menstrual blood loss from Always Ultra sanitary towels that contain superabsorbent polymers. Copyright © 2010 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

Electrochemical performance of an air-breathing direct methanol fuel cell using poly(vinyl alcohol)/hydroxyapatite composite polymer membrane

NASA Astrophysics Data System (ADS)

Yang, Chun-Chen; Chiu, Shwu-Jer; Lin, Che-Tseng

A novel composite polymer membrane based on poly(vinyl alcohol)/hydroxyapatite (PVA/HAP) was successfully prepared by a solution casting method. The characteristic properties of the PVA/HAP composite polymer membranes were examined by thermal gravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), micro-Raman spectroscopy and AC impedance method. An air-breathing DMFC, comprised of an air cathode electrode with MnO 2/BP2000 carbon inks on Ni-foam, an anode electrode with PtRu black on Ti-mesh, and the PVA/HAP composite polymer membrane, was assembled and studied. It was found that this alkaline DMFC showed an improved electrochemical performance at ambient temperature and pressure; the maximum peak power density of an air-breathing DMFC in 8 M KOH + 2 M CH 3OH solution is about 11.48 mW cm -2. From the application point of view, these composite polymer membranes show a high potential for the DMFC applications.

High-performance alkaline direct methanol fuel cell using a nitrogen-postdoped anode.

PubMed

Joghee, Prabhuram; Pylypenko, Svitlana; Wood, Kevin; Bender, Guido; O'Hayre, Ryan

2014-07-01

A commercial PtRu/C catalyst postdoped with nitrogen demonstrates a significantly higher performance (~10-20% improvement) in the anode of an alkaline direct methanol fuel cell than an unmodified commercial PtRu/C catalyst control. The enhanced performance shown herein is attributed at least partially to the increased electrochemical surface area of the PtRu/C after postdoping with nitrogen. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Polyester polymer alloy as a high-performance membrane.

PubMed

Igoshi, Tadaaki; Tomisawa, Narumi; Hori, Yoshinori; Jinbo, Yoichi

2011-01-01

Polyester polymer alloy (PEPA) membrane is developed as a synthetic polymermembrane. It consists of two polymers - polyethersulfone (PES) and polyarylate (PAR).The pore size in membrane can be controlled by a blend ratio of PES and PAR. One unique characteristic is that PEPA membrane has three layers of a skin layer on the inner surface, a porous layer in the membrane, and a skin layer on the outer surface, respectively. The permeability of water and substances is controlled by the skin layer on the inner surface. PEPA membrane dialyzer can be adequately considered as a high-performance dialyzer. Furthermore, the skin layer on the outer surface can block endotoxin from the dialysis fluid side. PEPA membrane can therefore be used as an endotoxin-retentive filter. The other unique characteristic is that each amount of albumin loss or β2-microglobulin removal can be controlled by an additive amount of polyvinylpyrrolidone. This means that the PEPA dialyzer can be clinically used to meet the conditions of the patient. Copyright © 2011 S. Karger AG, Basel.

Polymer waveguides for electro-optical integration in data centers and high-performance computers.

PubMed

Dangel, Roger; Hofrichter, Jens; Horst, Folkert; Jubin, Daniel; La Porta, Antonio; Meier, Norbert; Soganci, Ibrahim Murat; Weiss, Jonas; Offrein, Bert Jan

2015-02-23

To satisfy the intra- and inter-system bandwidth requirements of future data centers and high-performance computers, low-cost low-power high-throughput optical interconnects will become a key enabling technology. To tightly integrate optics with the computing hardware, particularly in the context of CMOS-compatible silicon photonics, optical printed circuit boards using polymer waveguides are considered as a formidable platform. IBM Research has already demonstrated the essential silicon photonics and interconnection building blocks. A remaining challenge is electro-optical packaging, i.e., the connection of the silicon photonics chips with the system. In this paper, we present a new single-mode polymer waveguide technology and a scalable method for building the optical interface between silicon photonics chips and single-mode polymer waveguides.

Clonal Integration Enhances the Performance of a Clonal Plant Species under Soil Alkalinity Stress

PubMed Central

Sun, Juanjuan; Chen, Jishan; Zhang, Yingjun

2015-01-01

Clonal plants have been shown to successfully survive in stressful environments, including salinity stress, drought and depleted nutrients through clonal integration between original and subsequent ramets. However, relatively little is known about whether clonal integration can enhance the performance of clonal plants under alkalinity stress. We investigated the effect of clonal integration on the performance of a typical rhizomatous clonal plant, Leymus chinensis, using a factorial experimental design with four levels of alkalinity and two levels of rhizome connection treatments, connected (allowing integration) and severed (preventing integration). Clonal integration was estimated by comparing physiological and biomass features between the rhizome-connected and rhizome-severed treatments. We found that rhizome-connected treatment increased the biomass, height and leaf water potential of subsequent ramets at highly alkalinity treatments but did not affect them at low alkalinity treatments. However, rhizome-connected treatment decreased the root biomass of subsequent ramets and did not influence the photosynthetic rates of subsequent ramets. The biomass of original ramets was reduced by rhizome-connected treatment at the highest alkalinity level. These results suggest that clonal integration can increase the performance of clonal plants under alkalinity stress. Rhizome-connected plants showed dramatically increased survival of buds with negative effects on root weight, indicating that clonal integration influenced the resource allocation pattern of clonal plants. A cost-benefit analysis based on biomass measures showed that original and subsequent ramets significantly benefited from clonal integration in highly alkalinity stress, indicating that clonal integration is an important adaptive strategy by which clonal plants could survive in local alkalinity soil. PMID:25790352

High Performance Solid Polymer Electrolytes for Rechargeable Batteries: A Self-Catalyzed Strategy toward Facile Synthesis.

PubMed

Cui, Yanyan; Liang, Xinmiao; Chai, Jingchao; Cui, Zili; Wang, Qinglei; He, Weisheng; Liu, Xiaochen; Liu, Zhihong; Cui, Guanglei; Feng, Jiwen

2017-11-01

It is urgent to seek high performance solid polymer electrolytes (SPEs) via a facile chemistry and simple process. The lithium salts are composed of complex anions that are stabilized by a Lewis acid agent. This Lewis acid can initiate the ring opening polymerization. Herein, a self-catalyzed strategy toward facile synthesis of crosslinked poly(ethylene glycol) diglycidyl ether-based solid polymer electrolyte (C-PEGDE) is presented. It is manifested that the poly(ethylene glycol) diglycidyl ether-based solid polymer electrolyte possesses a superior electrochemical stability window up to 4.5 V versus Li/Li + and considerable ionic conductivity of 8.9 × 10 -5 S cm -1 at ambient temperature. Moreover, the LiFePO 4 /C-PEGDE/Li batteries deliver stable charge/discharge profiles and considerable rate capability. It is demonstrated that this self-catalyzed strategy can be a very effective approach for high performance solid polymer electrolytes.

Technetium recovery from high alkaline solution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nash, Charles A.

2016-07-12

Disclosed are methods for recovering technetium from a highly alkaline solution. The highly alkaline solution can be a liquid waste solution from a nuclear waste processing system. Methods can include combining the solution with a reductant capable of reducing technetium at the high pH of the solution and adding to or forming in the solution an adsorbent capable of adsorbing the precipitated technetium at the high pH of the solution.

Cyclopentadithiophene-Benzothiadiazole Donor-Acceptor Polymers as Prototypical Semiconductors for High-Performance Field-Effect Transistors.

PubMed

Li, Mengmeng; An, Cunbin; Pisula, Wojciech; Müllen, Klaus

2018-05-15

Donor-acceptor (D-A) conjugated polymers are of great interest as organic semiconductors, because they offer a rational tailoring of the electronic properties by modification of the donor and acceptor units. Nowadays, D-A polymers exhibit field-effect mobilities on the order of 10 -2 -10 0 cm 2 V -1 s -1 , while several examples showed a mobility over 10 cm 2 V -1 s -1 . The development of cyclopentadithiophene-benzothiadiazole (CDT-BTZ) copolymers one decade ago represents an important step toward high-performance organic semiconductors for field-effect transistors. The significant rise in field-effect mobility of CDT-BTZ in comparison to the existing D-A polymers at that time opened the door to a new research field with a large number of novel D-A systems. From this point, the device performance of CDT-BTZ was gradually improved by a systematic optimization of the synthesis and polymer structure as well as by an efficient solution processing into long-range ordered thin films. The key aspect was a comprehensive understanding of the relation between polymer structure and solid-state organization. Due to their fundamental role for the field of D-A polymers in general, this Account will for the first time explicitly focus on prototypical CDT-BTZ polymers, while other reviews provide an excellent general overview on D-A polymers. The first part of this Account discusses strategies for improving the charge carrier transport, focusing on chemical aspects. Improved synthesis as an essential stage toward high purity, and high molecular weight is a prerequisite for molecular order. The modification of substituents is a further crucial feature to tune the CDT-BTZ packing and self-assembly. Linear alkyl side chains facilitate intermolecular π-stacking interactions, while branched ones increase solubility and alter the polymer packing. Additional control over the supramolecular organization of CDT-BTZ polymers is introduced by alkenyl substituents via their cis

The influence of alkalinity of portland cement on the absorption characteristics of superabsorbent polymers (SAP) for use in internally cured concrete

NASA Astrophysics Data System (ADS)

Tabares Tamayo, Juan D.

The concrete industry increasingly emphasizes advances in novel materials that promote construction of more resilient infrastructure. Due to its potential to improve concrete durability, internal curing (IC) of concrete by means of superabsorbent polymers (SAP) has been identified as one of the most promising technologies of the 21st century. The addition of superabsorbent polymers into a cementitious system promotes further hydration of cement by providing internal moisture during the hardening and strength development periods, and thus limits self-desiccation, shrinkage, and cracking. This thesis presents the work performed on the series of cement pastes with varying alkalinity of their pore solutions to provide a better understanding of: (1) the influence of the chemistry of the pore solution (i.e. its level of alkalinity and the type of ionic species present) on the absorption capacity of SAP, and (2) the effectiveness of SAP with different absorption capacities as an internal curing agent. This research work was divided into three stages: (a) materials characterization, (b) measurement of absorption capacity of SAP in synthetic pore solutions, and (c) evaluation of the internal curing effectiveness of SAP. During the first stage (Materials Characterization), pore solutions were extracted from the fresh (5 minutes old) cement pastes prepared using cements with three different levels of alkalinity. The pH values of the extracted solutions were determined (using the pH meter) and their chemical analysis was performed by means of titration (concentration of hydroxyl), ion chromatography (sulfates and chlorides), atomic absorption (AA) and inductively coupled plasma optical emission spectrometry (ICP) (sodium, potassium and calcium). The commercial SAP adopted for this study was used with "as-supplied" gradation and with the finer gradation obtained by grinding the original polymer in the 6850 Cryomilling Freezer/Mill. The physical properties of these SAP's, such

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

High-Performance Organic Photodetectors from a High-Bandgap Indacenodithiophene-Based π-Conjugated Donor-Acceptor Polymer.

PubMed

Benavides, Cindy Montenegro; Murto, Petri; Chochos, Christos L; Gregoriou, Vasilis G; Avgeropoulos, Apostolos; Xu, Xiaofeng; Bini, Kim; Sharma, Anirudh; Andersson, Mats R; Schmidt, Oliver; Brabec, Christoph J; Wang, Ergang; Tedde, Sandro F

2018-04-18

A conjugated donor-acceptor polymer, poly[4,4,9,9-tetrakis(4-hexylphenyl)-4,9-dihydro- s-indaceno[1,2- b:5,6- b']dithiophene-2,7-diyl- alt-5-(2-ethylhexyl)-4 H-thieno[3,4- c]pyrrole-4,6(5 H)-dione-1,3-diyl] (PIDT-TPD), is blended with the fullerene derivative [6,6]phenyl-C61-butyric acid methyl ester (PC 61 BM) for the fabrication of thin and solution-processed organic photodetectors (OPDs). Systematic screening of the concentration ratio of the blend and the molecular weight of the polymer is performed to optimize the active layer morphology and the OPD performance. The device comprising a medium molecular weight polymer (27.0 kg/mol) in a PIDT-TPD:PC 61 BM 1:1 ratio exhibits an external quantum efficiency of 52% at 610 nm, a dark current density of 1 nA/cm 2 , a detectivity of 1.44 × 10 13 Jones, and a maximum 3 dB cutoff frequency of 100 kHz at -5 V bias. These results are remarkable among the state-of-the-art red photodetectors based on conjugated polymers. As such, this work presents a functional organic active material for high-speed OPDs with a linear photoresponse at different light intensities.

High Performance Solid Polymer Electrolytes for Rechargeable Batteries: A Self‐Catalyzed Strategy toward Facile Synthesis

PubMed Central

Cui, Yanyan; Liang, Xinmiao; Chai, Jingchao; Cui, Zili; Wang, Qinglei; He, Weisheng; Liu, Xiaochen; Feng, Jiwen

2017-01-01

Abstract It is urgent to seek high performance solid polymer electrolytes (SPEs) via a facile chemistry and simple process. The lithium salts are composed of complex anions that are stabilized by a Lewis acid agent. This Lewis acid can initiate the ring opening polymerization. Herein, a self‐catalyzed strategy toward facile synthesis of crosslinked poly(ethylene glycol) diglycidyl ether‐based solid polymer electrolyte (C‐PEGDE) is presented. It is manifested that the poly(ethylene glycol) diglycidyl ether‐based solid polymer electrolyte possesses a superior electrochemical stability window up to 4.5 V versus Li/Li+ and considerable ionic conductivity of 8.9 × 10−5 S cm−1 at ambient temperature. Moreover, the LiFePO4/C‐PEGDE/Li batteries deliver stable charge/discharge profiles and considerable rate capability. It is demonstrated that this self‐catalyzed strategy can be a very effective approach for high performance solid polymer electrolytes. PMID:29201612

Free-Standing Conducting Polymer Films for High-Performance Energy Devices.

PubMed

Li, Zaifang; Ma, Guoqiang; Ge, Ru; Qin, Fei; Dong, Xinyun; Meng, Wei; Liu, Tiefeng; Tong, Jinhui; Jiang, Fangyuan; Zhou, Yifeng; Li, Ke; Min, Xue; Huo, Kaifu; Zhou, Yinhua

2016-01-18

Thick, uniform, easily processed, highly conductive polymer films are desirable as electrodes for solar cells as well as polymer capacitors. Here, a novel scalable strategy is developed to prepare highly conductive thick poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (HCT-PEDOT:PSS) films with layered structure that display a conductivity of 1400 S cm(-1) and a low sheet resistance of 0.59 ohm sq(-1). Organic solar cells with laminated HCT-PEDOT:PSS exhibit a performance comparable to the reference devices with vacuum-deposited Ag top electrodes. More importantly, the HCT-PEDOT:PSS film delivers a specific capacitance of 120 F g(-1) at a current density of 0.4 A g(-1). All-solid-state flexible symmetric supercapacitors with the HCT-PEDOT:PSS films display a high volumetric energy density of 6.80 mWh cm(-3) at a power density of 100 mW cm(-3) and 3.15 mWh cm(-3) at a very high power density of 16160 mW cm(-3) that outperforms previous reported solid-state supercapacitors based on PEDOT materials. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

Taichi-inspired rigid-flexible coupling cellulose-supported solid polymer electrolyte for high-performance lithium batteries

PubMed Central

Zhang, Jianjun; Yue, Liping; Hu, Pu; Liu, Zhihong; Qin, Bingsheng; Zhang, Bo; Wang, Qingfu; Ding, Guoliang; Zhang, Chuanjian; Zhou, Xinhong; Yao, Jianhua; Cui, Guanglei; Chen, Liquan

2014-01-01

Inspired by Taichi, we proposed rigid-flexible coupling concept and herein developed a highly promising solid polymer electrolyte comprised of poly (ethylene oxide), poly (cyano acrylate), lithium bis(oxalate)borate and robust cellulose nonwoven. Our investigation revealed that this new class solid polymer electrolyte possessed comprehensive properties in high mechanical integrity strength, sufficient ionic conductivity (3 × 10−4 S cm−1) at 60°C and improved dimensional thermostability (up to 160°C). In addition, the lithium iron phosphate (LiFePO4)/lithium (Li) cell using such solid polymer electrolyte displayed superior rate capacity (up to 6 C) and stable cycle performance at 80°C. Furthermore, the LiFePO4/Li battery could also operate very well even at an elevated temperature of 160°C, thus improving enhanced safety performance of lithium batteries. The use of this solid polymer electrolyte mitigates the safety risk and widens the operation temperature range of lithium batteries. Thus, this fascinating study demonstrates a proof of concept of the use of rigid-flexible coupling solid polymer electrolyte toward practical lithium battery applications with improved reliability and safety. PMID:25183416

Study on dissolution behavior of polymer-bound and polymer-blended photo-acid generator (PAG) resists

NASA Astrophysics Data System (ADS)

Yamamoto, Hiroki; Kozawa, Takahiro; Tagawa, Seiichi

2013-03-01

The requirements for the next generation resist materials are so challenging that it is indispensable for feasibility of EUV lithography to grasp basic chemistry of resist matrices in all stage of resist processes. Under such circumstances, it is very important to know dissolution characteristics of the resist film into alkaline developer though the dissolution of exposed area of resist films in alkaline developer to form a pattern is a complex reactive process. In this study, the influence of EUV and KrF exposure on the dissolution behavior of polymer bound PAG and polymer blended PAG was studied in detail using quartz crystal microbalance (QCM) methods. The difference in swelling formation between KrF and EUV exposure was observed. It is likely that difference of reaction mechanism induces the difference of these swelling. Also, it is observed that the swelling of polymer-bound PAG is less than that of polymer blended PAG in both KrF and EUV exposure. This result indicates that polymer-bound PAG suppresses swelling very well and showed an excellent performance. Actually, the developed polymer bound-PAG resist showed an excellent performance (half pitch 50 nm line and space pattern). Thus, polymer bound PAG is one of the promising candidate for 16 nm EUV resist.

n-Type Water/Alcohol-Soluble Naphthalene Diimide-Based Conjugated Polymers for High-Performance Polymer Solar Cells.

PubMed

Wu, Zhihong; Sun, Chen; Dong, Sheng; Jiang, Xiao-Fang; Wu, Siping; Wu, Hongbin; Yip, Hin-Lap; Huang, Fei; Cao, Yong

2016-02-17

With the demonstration of small-area, single-junction polymer solar cells (PSCs) with power conversion efficiencies (PCEs) over the 10% performance milestone, the manufacturing of high-performance large-area PSC modules is becoming the most critical issue for commercial applications. However, materials and processes that are optimized for fabricating small-area devices may not be applicable for the production of high-performance large-area PSC modules. One of the challenges is to develop new conductive interfacial materials that can be easily processed with a wide range of thicknesses without significantly affecting the performance of the PSCs. Toward this goal, we report two novel naphthalene diimide-based, self-doped, n-type water/alcohol-soluble conjugated polymers (WSCPs) that can be processed with a broad thickness range of 5 to 100 nm as efficient electron transporting layers (ETLs) for high-performance PSCs. Space charge limited current and electron spin resonance spectroscopy studies confirm that the presence of amine or ammonium bromide groups on the side chains of the WSCP can n-dope PC71BM at the bulk heterojunction (BHJ)/ETL interface, which improves the electron extraction properties at the cathode. In addition, both amino functional groups can induce self-doping to the WSCPs, although by different doping mechanisms, which leads to highly conductive ETLs with reduced ohmic loss for electron transport and extraction. Ultimately, PSCs based on the self-doped WSCP ETLs exhibit significantly improved device performance, yielding PCEs as high as 9.7% and 10.11% for PTB7-Th/PC71BM and PffBT4T-2OD/PC71BM systems, respectively. More importantly, with PffBT4T-2OD/PC71BM BHJ as an active layer, a prominent PCE of over 8% was achieved even when a thick ETL of 100 nm was used. To the best of our knowledge, this is the highest efficiency demonstrated for PSCs with a thick interlayer and light-harvesting layer, which are important criteria for eventually making

Medium Bandgap Conjugated Polymer for High Performance Polymer Solar Cells Exceeding 9% Power Conversion Efficiency.

PubMed

Jung, Jae Woong; Liu, Feng; Russell, Thomas P; Jo, Won Ho

2015-12-02

Two medium-bandgap polymers composed of benzo[1,2-b:4,5-b']dithiohpene and 2,1,3-benzothiadiazole with 6-octyl-thieno[3,2-b]thiophene as a π-bridge unit are synthesized and their photovoltaic properties are analyzed. The two polymers have deep highest occupied molecular orbital energy levels, high crystallinity, optimal bulk-heterojunction morphology, and efficient charge transport, resulting in a power conversion efficiency of as high as 9.44% for a single-junction polymer solar-cell device. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Solution Adsorption Formation of a π-Conjugated Polymer/Graphene Composite for High-Performance Field-Effect Transistors.

PubMed

Liu, Yun; Hao, Wei; Yao, Huiying; Li, Shuzhou; Wu, Yuchen; Zhu, Jia; Jiang, Lei

2018-01-01

Semiconducting polymers with π-conjugated electronic structures have potential application in the large-scale printable fabrication of high-performance electronic and optoelectronic devices. However, owing to their poor environmental stability and high-cost synthesis, polymer semiconductors possess limited device implementation. Here, an approach for constructing a π-conjugated polymer/graphene composite material to circumvent these limitations is provided, and then this material is patterned into 1D arrays. Driven by the π-π interaction, several-layer polymers can be adsorbed onto the graphene planes. The low consumption of the high-cost semiconductor polymers and the mass production of graphene contribute to the low-cost fabrication of the π-conjugated polymer/graphene composite materials. Based on the π-conjugated system, a reduced π-π stacking distance between graphene and the polymer can be achieved, yielding enhanced charge-transport properties. Owing to the incorporation of graphene, the composite material shows improved thermal stability. More generally, it is believed that the construction of the π-conjugated composite shows clear possibility of integrating organic molecules and 2D materials into microstructure arrays for property-by-design fabrication of functional devices with large area, low cost, and high efficiency. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Polymer/graphite oxide composites as high-performance materials for electric double layer capacitors

NASA Astrophysics Data System (ADS)

Tien, Chien-Pin; Teng, Hsisheng

A single graphene sheet represents a carbon material with the highest surface area available to accommodating molecules or ions for physical and chemical interactions. Here we demonstrate in an electric double layer capacitor the outstanding performance of graphite oxide for providing a platform for double layer formation. Graphite oxide is generally the intermediate compound for obtaining separated graphene sheets. Instead of reduction with hydrazine, we incorporate graphite oxide with a poly(ethylene oxide)-based polymer and anchor the graphene oxide sheets with poly(propylene oxide) diamines. This polymer/graphite oxide composite shows in a "dry" gel-electrolyte system a double layer capacitance as high as 130 F g -1. The polymer incorporation developed here can significantly diversify the application of graphene-based materials in energy storage devices.

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

2016-06-02

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.

High-Performance Polymers Sandwiched with Chemical Vapor Deposited Hexagonal Boron Nitrides as Scalable High-Temperature Dielectric Materials.

PubMed

Azizi, Amin; Gadinski, Matthew R; Li, Qi; AlSaud, Mohammed Abu; Wang, Jianjun; Wang, Yi; Wang, Bo; Liu, Feihua; Chen, Long-Qing; Alem, Nasim; Wang, Qing

2017-09-01

Polymer dielectrics are the preferred materials of choice for power electronics and pulsed power applications. However, their relatively low operating temperatures significantly limit their uses in harsh-environment energy storage devices, e.g., automobile and aerospace power systems. Herein, hexagonal boron nitride (h-BN) films are prepared from chemical vapor deposition (CVD) and readily transferred onto polyetherimide (PEI) films. Greatly improved performance in terms of discharged energy density and charge-discharge efficiency is achieved in the PEI sandwiched with CVD-grown h-BN films at elevated temperatures when compared to neat PEI films and other high-temperature polymer and nanocomposite dielectrics. Notably, the h-BN-coated PEI films are capable of operating with >90% charge-discharge efficiencies and delivering high energy densities, i.e., 1.2 J cm -3 , even at a temperature close to the glass transition temperature of polymer (i.e., 217 °C) where pristine PEI almost fails. Outstanding cyclability and dielectric stability over a straight 55 000 charge-discharge cycles are demonstrated in the h-BN-coated PEI at high temperatures. The work demonstrates a general and scalable pathway to enable the high-temperature capacitive energy applications of a wide range of engineering polymers and also offers an efficient method for the synthesis and transfer of 2D nanomaterials at the scale demanded for applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

Alkaline fuel cell performance investigation

NASA Technical Reports Server (NTRS)

Martin, R. E.; Manzo, M. A.

1988-01-01

An exploratory experimental fuel cell test program was conducted to investigate the performance characteristics of alkaline laboratory research electrodes. The objective of this work was to establish the effect of temperature, pressure, and concentration upon performance and evaluate candidate cathode configurations having the potential for improved performance. The performance characterization tests provided data to empirically establish the effect of temperature, pressure, and concentration upon performance for cell temperatures up to 300 F and reactant pressures up to 200 psia. Evaluation of five gold alloy cathode catalysts revealed that three doped gold alloys had more that two times the surface areas of reference cathodes and therefore offered the best potential for improved performance.

Alkaline fuel cell performance investigation

NASA Technical Reports Server (NTRS)

Martin, R. E.; Manzo, M. A.

1988-01-01

An exploratory experimental fuel cell test program was conducted to investigate the performance characteristics of alkaline laboratory research electrodes. The objective of this work was to establish the effect of temperature, pressure, and concentration upon performance and evaluate candidate cathode configurations having the potential for improved performance. The performance characterization tests provided data to empirically establish the effect of temperature, pressure, and concentration upon performance for cell temperatures up to 300 F and reactant pressures up to 200 psia. Evaluation of five gold alloy cathode catalysts revealed that three doped gold alloys had more than two times the surface areas of reference cathodes and therefore offered the best potential for improved performance.

Modification of polymer velvet cathode via metallic Mo coating for enhancement of high-current electron emission performances

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xiong, Ying; Wang, Bing; Yi, Yong

2013-09-15

The effect of surface Mo coating on the high-current electron emission performances for polymer velvet cathode has been investigated in a diode with A-K gap of 11.5 cm by the combination of time-resolved electrical diagnostic and temporal pressure variation. Compared with uncoated polymer velvet cathode under the single-pulsed emission mode, the Mo-coated one shows lower outgassing levels (∼0.40 Pa L), slower cathode plasma expansion velocity (∼2.30 cm/μs), and higher emission stability as evidences by the change in cathode current, temporal pressure variation, and diode perveance. Moreover, after Mo coating, the emission consistency of the polymer velvet cathode between two adjacentmore » pulses is significantly improved in double-pulsed emission mode with ∼500 ns interval between two pulses, which further confirms the effectiveness of Mo coating for enhancement of electron emission performance of polymer velvet cathodes. These results should be of interest to the high-repetitive high-power microwave systems with cold cathodes.« less

High-performance polymer waveguide devices via low-cost direct photolithography process

NASA Astrophysics Data System (ADS)

Wang, Jianguo; Shustack, Paul J.; Garner, Sean M.

2002-09-01

All-optical networks provide unique opportunities for polymer waveguide devices because of their excellent mechanical, thermo-optic, and electro-optic properties. Polymer materials and components have been viewed as a viable solution for metropolitan and local area networks where high volume and low cost components are needed. In this paper, we present our recent progress on the design and development of photoresist-like highly fluorinated maleimide copolymers including waveguide fabrication and optical testing. We have developed and synthesized a series of thermally stable, (Tg>150 oC, Td>300 oC) highly fluorinated (>50%) maleimide copolymers by radical co-polymerization of halogenated maleimides with various halogenated co-monomers. A theoretical correlation between optical loss and different co-polymer structures has been quantitatively established from C-H overtone analysis. We studied this correlation through design and manipulation of the copolymer structure by changing the primary properties such as molecular weight, copolymer composition, copolymer sequence distribution, and variations of the side chain including photochemically functional side units. Detailed analysis has been obtained using various characterization methods such as (H, C13, F19) NMR, UV-NIR, FTIR, GPC and so forth. The co-polymers exhibit excellent solubility in ketone solvents and high quality thin films can be prepared by spin coating. The polymer films were found to have a refractive index range of 1.42-1.67 and optical loss in the range of 0.2 to 0.4 dB/cm at 1550nm depending on the composition as extrapolated from UV-NIR spectra. When glycidyl methacrylate is incorporated into the polymer backbone, the material behaves like a negative photoresist with the addition of cationic photoinitiator. The final crosslinked waveguides show excellent optical and thermal properties. The photolithographic processing of the highly fluorinated copolymer material was examined in detail using in

Rational material, interface, and device engineering for high-performance polymer and perovskite solar cells (Presentation Recording)

NASA Astrophysics Data System (ADS)

Jen, Alex K.

2015-10-01

The performance of polymer and hybrid solar cells is also strongly dependent on their efficiency in harvesting light, exciton dissociation, charge transport, and charge collection at the metal/organic/metal oxide or the metal/perovskite/metal oxide interfaces. Our laboratory employs a molecular engineering approach to develop processible low band-gap polymers with high charge carrier mobility that can enhance power conversion efficiency of the single junction solar cells to values as high as ~11%. We have also developed several innovative strategies to modify the interface of bulk-heterojunction devices and create new device architectures to fully explore their potential for solar applications. In this talk, the integrated approach of combining material design, interface, and device engineering to significantly improve the performance of polymer and hybrid perovskite photovoltaic cells will be discussed. Specific emphasis will be placed on the development of low band-gap polymers with reduced reorganizational energy and proper energy levels, formation of optimized morphology of active layer, and minimized interfacial energy barriers using functional conductive surfactants. At the end, several new device architectures and optical engineering strategies to make tandem cells and semitransparent solar cells will be discussed to explore the full promise of polymer and perovskite hybrid solar cells.

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

Long-term evolution of highly alkaline steel slag drainage waters.

PubMed

Riley, Alex L; Mayes, William M

2015-07-01

The disposal of slag generated by the steel industry can have negative consequences upon the surrounding aquatic environment by the generation of high pH waters, leaching of potentially problematic trace metals, and rapid rates of calcite precipitation which smother benthic habitats. A 36-year dataset was collated from the long-term ambient monitoring of physicochemical parameters and elemental concentrations of samples from two steel slag leachate-affected watercourses in northern England. Waters were typified by elevated pH (>10), high alkalinity, and were rich in dissolved metals (e.g. calcium (Ca), aluminium (Al), and zinc (Zn)). Long-term trend analysis was performed upon pH, alkalinity, and Ca concentration which, in addition to Ca flux calculations, were used to highlight the longevity of pollution arising as a result of the dumping and subsequent leaching of steel slags. Declines in calcium and alkalinity have been modest over the monitoring period and not accompanied by significant declines in water pH. If the monotonic trends of decline in alkalinity and calcium continue in the largest of the receiving streams, it will be in the region of 50-80 years before calcite precipitation would be expected to be close to baseline levels, where ecological impacts would be negligible.

Trap Healing for High-Performance Low-Voltage Polymer Transistors and Solution-Based Analog Amplifiers on Foil.

PubMed

Pecunia, Vincenzo; Nikolka, Mark; Sou, Antony; Nasrallah, Iyad; Amin, Atefeh Y; McCulloch, Iain; Sirringhaus, Henning

2017-06-01

Solution-processed semiconductors such as conjugated polymers have great potential in large-area electronics. While extremely appealing due to their low-temperature and high-throughput deposition methods, their integration in high-performance circuits has been difficult. An important remaining challenge is the achievement of low-voltage circuit operation. The present study focuses on state-of-the-art polymer thin-film transistors based on poly(indacenodithiophene-benzothiadiazole) and shows that the general paradigm for low-voltage operation via an enhanced gate-to-channel capacitive coupling is unable to deliver high-performance device behavior. The order-of-magnitude longitudinal-field reduction demanded by low-voltage operation plays a fundamental role, enabling bulk trapping and leading to compromised contact properties. A trap-reduction technique based on small molecule additives, however, is capable of overcoming this effect, allowing low-voltage high-mobility operation. This approach is readily applicable to low-voltage circuit integration, as this work exemplifies by demonstrating high-performance analog differential amplifiers operating at a battery-compatible power supply voltage of 5 V with power dissipation of 11 µW, and attaining a voltage gain above 60 dB at a power supply voltage below 8 V. These findings constitute an important milestone in realizing low-voltage polymer transistors for solution-based analog electronics that meets performance and power-dissipation requirements for a range of battery-powered smart-sensing applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

High-Efficiency Artificial Photosynthesis Using a Novel Alkaline Membrane Cell

NASA Technical Reports Server (NTRS)

Narayan, Sri; Haines, Brennan; Blosiu, Julian; Marzwell, Neville

2009-01-01

A new cell designed to mimic the photosynthetic processes of plants to convert carbon dioxide into carbonaceous products and oxygen at high efficiency, has an improved configuration using a polymer membrane electrolyte and an alkaline medium. This increases efficiency of the artificial photosynthetic process, achieves high conversion rates, permits the use of inexpensive catalysts, and widens the range of products generated by this type of process. The alkaline membrane electrolyte allows for the continuous generation of sodium formate without the need for any additional separation system. The electrolyte type, pH, electrocatalyst type, and cell voltage were found to have a strong effect on the efficiency of conversion of carbon dioxide to formate. Indium electrodes were found to have higher conversion efficiency compared to lead. Bicarbonate electrolyte offers higher conversion efficiency and higher rates than water solutions saturated with carbon dioxide. pH values between 8 and 9 lead to the maximum values of efficiency. The operating cell voltage of 2.5 V, or higher, ensures conversion of the carbon dioxide to formate, although the hydrogen evolution reaction begins to compete strongly with the formate production reaction at higher cell voltages. Formate is produced at indium and lead electrodes at a conversion efficiency of 48 mg of CO2/kilojoule of energy input. This efficiency is about eight times that of natural photosynthesis in green plants. The electrochemical method of artificial photosynthesis is a promising approach for the conversion, separation and sequestration of carbon dioxide for confined environments as in space habitats, and also for carbon dioxide management in the terrestrial context. The heart of the reactor is a membrane cell fabricated from an alkaline polymer electrolyte membrane and catalyst- coated electrodes. This cell is assembled and held in compression in gold-plated hardware. The cathode side of the cell is supplied with carbon

Supramolecular Polymer Network-Mediated Self-Assembly of Semicrystalline Polymers with Excellent Crystalline Performance.

PubMed

Cheng, Chih-Chia; Chuang, Wei-Tsung; Lee, Duu-Jong; Xin, Zhong; Chiu, Chih-Wei

2017-03-01

A novel application of supramolecular interactions within semicrystalline polymers, capable of self-assembling into supramolecular polymer networks via self-complementary multiple hydrogen-bonded complexes, is demonstrated for efficient construction of highly controlled self-organizing hierarchical structures to offer a direct, efficient nucleation pathway resulting in superior crystallization performance. Herein, a novel functionalized poly(ε-caprolactone) containing self-complementary sextuple hydrogen-bonded uracil-diamidopyridine (U-DPy) moieties is successfully developed and demonstrated excellent thermal and viscoelastic properties as well as high dynamic structural stability in the bulk state due to physical cross-linking created by reversible sextuple hydrogen bonding between U-DPy units. Due to the ability to vary the extent of the reversible network by tuning the U-DPy content, this newly developed material can be readily adjusted to obtain the desired crystalline products with specific characteristics. Importantly, incorporating only 0.1% U-DPy resulted in a polymer with a high crystallization rate constant, short crystallization half-time, and much more rapid crystallization kinetics than pristine PCL, indicating a low content of U-DPy moieties provides highly efficient nucleation sites that manipulate the nucleation and growth processes of polymer crystals to promote crystallization and chain alignment in bulk. This new system is suggested as a potential new route to substantially improve the performance of polymer crystallization. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Two 3D structured Co-Ni bimetallic oxides as cathode catalysts for high-performance alkaline direct methanol fuel cells

NASA Astrophysics Data System (ADS)

Liu, Yan; Shu, Chengyong; Fang, Yuan; Chen, Yuanzhen; Liu, Yongning

2017-09-01

Two NiCo2O4 bimetallic oxides were synthesized via a facile hydrothermal method. SEM and TEM observations show that these materials have three-dimensional (3D) dandelion-like (DL) and flower-like (FL) morphologies. Their large specific surface areas (90.68 and 19.8 m2·g-1) and porous structures provide many active sites and effective transport pathways for the oxygen reduction reaction (ORR). Electrochemical measurements with a rotating ring-disc electrode (RRDE) indicate that the electron transfer numbers of the NiCo2O4-DL and NiCo2O4-FL catalysts for ORR in an alkaline solution are 3.97 and 3.91, respectively. Fuel cells were assembled with the bimetallic oxides, PtRu/C and a polymer fiber membrane (PFM) as cathode catalysts, anode catalyst and electrolyte film, respectively. For NiCo2O4-DL, the peak power density reaches up to 73.5 mW·cm-2 at 26 °C, which is the highest room-temperature value reported to date. The high catalytic activity of NiCo2O4 is mainly attributed to the presence of many Co3+ cations that directly donate electrons to O2 to reduce it via a more efficient and effective route. Furthermore, the catalytic performance of NiCo2O4-DL is superior to that of NiCo2O4-FL because it has a higher specific surface area and is less crystalline.

High-performance, polymer-based direct cellular interfaces for electrical stimulation and recording

NASA Astrophysics Data System (ADS)

Kim, Seong-Min; Kim, Nara; Kim, Youngseok; Baik, Min-Seo; Yoo, Minsu; Kim, Dongyoon; Lee, Won-June; Kang, Dong-Hee; Kim, Sohee; Lee, Kwanghee; Yoon, Myung-Han

2018-04-01

Due to the trade-off between their electrical/electrochemical performance and underwater stability, realizing polymer-based, high-performance direct cellular interfaces for electrical stimulation and recording has been very challenging. Herein, we developed transparent and conductive direct cellular interfaces based on a water-stable, high-performance poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) film via solvent-assisted crystallization. The crystallized PEDOT:PSS on a polyethylene terephthalate (PET) substrate exhibited excellent electrical/electrochemical/optical characteristics, long-term underwater stability without film dissolution/delamination, and good viability for primarily cultured cardiomyocytes and neurons over several weeks. Furthermore, the highly crystallized, nanofibrillar PEDOT:PSS networks enabled dramatically enlarged surface areas and electrochemical activities, which were successfully employed to modulate cardiomyocyte beating via direct electrical stimulation. Finally, the high-performance PEDOT:PSS layer was seamlessly incorporated into transparent microelectrode arrays for efficient, real-time recording of cardiomyocyte action potentials with a high signal fidelity. All these results demonstrate the strong potential of crystallized PEDOT:PSS as a crucial component for a variety of versatile bioelectronic interfaces.

Hydroxide Self-Feeding High-Temperature Alkaline Direct Formate Fuel Cells.

PubMed

Li, Yinshi; Sun, Xianda; Feng, Ying

2017-05-22

Conventionally, both the thermal degradation of the anion-exchange membrane and the requirement of additional hydroxide for fuel oxidation reaction hinder the development of the high-temperature alkaline direct liquid fuel cells. The present work addresses these two issues by reporting a polybenzimidazole-membrane-based direct formate fuel cell (DFFC). Theoretically, the cell voltage of the high-temperature alkaline DFFC can be as high as 1.45 V at 90 °C. It has been demonstrated that a proof-of-concept alkaline DFFC without adding additional hydroxide yields a peak power density of 20.9 mW cm -2 , an order of magnitude higher than both alkaline direct ethanol fuel cells and alkaline direct methanol fuel cells, mainly because the hydrolysis of formate provides enough OH - ions for formate oxidation reaction. It was also found that this hydroxide self-feeding high-temperature alkaline DFFC shows a stable 100 min constant-current discharge at 90 °C, proving the conceptual feasibility. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Aggregation Strength Tuning in Difluorobenzoxadiazole-Based Polymeric Semiconductors for High-Performance Thick-Film Polymer Solar Cells.

PubMed

Chen, Peng; Shi, Shengbin; Wang, Hang; Qiu, Fanglong; Wang, Yuxi; Tang, Yumin; Feng, Jian-Rui; Guo, Han; Cheng, Xing; Guo, Xugang

2018-06-27

High-performance polymer solar cells (PSCs) with thick active layers are essential for large-scale production. Polymer semiconductors exhibiting a temperature-dependent aggregation property offer great advantages toward this purpose. In this study, three difluorobenzoxadiazole (ffBX)-based donor polymers, PffBX-T, PffBX-TT, and PffBX-DTT, were synthesized, which contain thiophene (T), thieno[3,2- b]thiophene (TT), and dithieno[3,2- b:2',3'- d]thiophene (DTT) as the π-spacers, respectively. Temperature-dependent absorption spectra reveal that the aggregation strength increases in the order of PffBX-T, PffBX-TT, and PffBX-DTT as the π-spacer becomes larger. PffBX-TT with the intermediate aggregation strength enables well-controlled disorder-order transition in the casting process of blend film, thus leading to the best film morphology and the highest performance in PSCs. Thick-film PSCs with an average power conversion efficiency (PCE) of 8.91% and the maximum value of 9.10% are achieved using PffBX-TT:PC 71 BM active layer with a thickness of 250 nm. The neat film of PffBX-TT also shows a high hole mobility of 1.09 cm 2 V -1 s -1 in organic thin-film transistors. When PffBX-DTT and PffBX-T are incorporated into PSCs utilizing PC 71 BM acceptor, the average PCE decreases to 6.54 and 1.33%, respectively. The performance drop mainly comes from reduced short-circuit current, as a result of nonoptimal blend film morphology caused by a less well-controlled film formation process. A similar trend was also observed in nonfullerene type thick-film PSCs using IT-4F as the electron acceptor. These results show the significance of polymer aggregation strength tuning toward optimal bulk heterojunction film morphology using ffBX-based polymer model system. The study demonstrates that adjusting π-spacer is an effective method, in combination with other important approaches such as alkyl chain optimization, to generate high-performance thick-film PSCs which are critical for

Acid-doped polymer nanofiber framework: Three-dimensional proton conductive network for high-performance fuel cells

NASA Astrophysics Data System (ADS)

Tanaka, Manabu; Takeda, Yasushi; Wakiya, Takeru; Wakamoto, Yuta; Harigaya, Kaori; Ito, Tatsunori; Tarao, Takashi; Kawakami, Hiroyoshi

2017-02-01

High-performance polymer electrolyte membranes (PEMs) with excellent proton conductivity, gas barrier property, and membrane stability are desired for future fuel cells. Here we report the development of PEMs based on our proposed new concept "Nanofiber Framework (NfF)." The NfF composite membranes composed of phytic acid-doped polybenzimidazole nanofibers (PBINf) and Nafion matrix show higher proton conductivity than the recast-Nafion membrane without nanofibers. A series of analyses reveal the formation of three-dimensional network nanostructures to conduct protons and water effectively through acid-condensed layers at the interface of PBINf and Nafion matrix. In addition, the NfF composite membrane achieves high gas barrier property and distinguished membrane stability. The fuel cell performance by the NfF composite membrane, which enables ultra-thin membranes with their thickness less than 5 μm, is superior to that by the recast-Nafion membrane, especially at low relative humidity. Such NfF-based high-performance PEM will be accomplished not only by the Nafion matrix used in this study but also by other polymer electrolyte matrices for future PEFCs.

High performance polymer chemical hydrogel-based electrode binder materials for direct borohydride fuel cells

NASA Astrophysics Data System (ADS)

Choudhury, Nurul A.; Ma, Jia; Sahai, Yogeshwar; Buchheit, Rudolph G.

Novel, cost-effective, high-performance, and environment-friendly electrode binders, comprising polyvinyl alcohol chemical hydrogel (PCH) and chitosan chemical hydrogel (CCH), are reported for direct borohydride fuel cells (DBFCs). PCH and CCH binders-based electrodes have been fabricated using a novel, simple, cost-effective, time-effective, and environmentally benign technique. Morphologies and electrochemical performance in DBFCs of the chemical hydrogel binder-based electrodes have been compared with those of Nafion ® binder-based electrodes. Relationships between the performance of binders in DBFCs with structural features of the polymers and the polymer-based chemical hydrogels are discussed. The CCH binder exhibited better performance than a Nafion ® binder whereas the PCH binder exhibited comparable performance to Nafion ® in DBFCs operating at elevated cell temperatures. The better performance of CCH binder at higher operating cell temperatures has been ascribed to the hydrophilic nature and water retention characteristics of chitosan. DBFCs employing CCH binder-based electrodes and a Nafion ®-117 membrane as an electrolyte exhibited a maximum peak power density of about 589 mW cm -2 at 70 °C.

Recent advances in solid polymer electrolyte fuel cell technology with low platinum loading electrodes

NASA Technical Reports Server (NTRS)

Srinivasan, Supramaniam; Manko, David J.; Koch, Hermann; Enayetullah, Mohammad A.; Appleby, A. John

1989-01-01

Of all the fuel cell systems only alkaline and solid polymer electrolyte fuel cells are capable of achieving high power densities (greater than 1 W/sq cm) required for terrestrial and extraterrestrial applications. Electrode kinetic criteria for attaining such high power densities are discussed. Attainment of high power densities in solid polymer electrolyte fuel cells has been demonstrated earlier by different groups using high platinum loading electrodes (4 mg/sq cm). Recent works at Los Alamos National Laboratory and at Texas A and M University (TAMU) demonstrated similar performance for solid polymer electrolyte fuel cells with ten times lower platinum loading (0.45 mg/sq cm) in the electrodes. Some of the results obtained are discussed in terms of the effects of type and thickness of membrane and of the methods platinum localization in the electrodes on the performance of a single cell.

Synthesis of poly(benzothiadiazole-co-dithienobenzodithiophenes) and effect of thiophene insertion for high-performance polymer solar cells.

PubMed

Yun, Hui-Jun; Lee, Yun-Ji; Yoo, Seung-Jin; Chung, Dae Sung; Kim, Yun-Hi; Kwon, Soon-Ki

2013-09-23

We describe herein the synthesis of novel donor-acceptor conjugated polymers with dithienobenzodithiophenes (DTBDT) as the electron donor and 2,1,3-benzothiadiazole as the electron acceptor for high-performance organic photovoltaics (OPVs). We studied the effects of strategically inserting thiophene into the DTBDT as a substituent on the skeletal structure on the opto-electronic performances of fabricated devices. From UV/Vis absorption, electrochemical, and field-effect transistor analyses, we found that the thiophene-containing DTBDT derivative can substantially increase the orbital overlap area between adjacent conjugated chains and thus dramatically enhance charge-carrier mobility up to 0.55 cm(2)  V(-1)  s(-1). The outstanding charge-transport characteristics of this polymer allowed the realization of high-performance organic solar cells with a power conversion efficiency (PCE) of 5.1 %. Detailed studies on the morphological factors that enable the maximum PCE of the polymer solar cells are discussed along with a hole/electron mobility analysis based on the space-charge-limited current model. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

High performance polymer solar cells with as-prepared zirconium acetylacetonate film as cathode buffer layer

PubMed Central

Tan, Zhan'ao; Li, Shusheng; Wang, Fuzhi; Qian, Deping; Lin, Jun; Hou, Jianhui; Li, Yongfang

2014-01-01

Low-work-function active metals are commonly used as cathode in polymer solar cells (PSCs), but sensitivity of the active metals towards moisture and oxygen results in poor stability of the devices. Therefore, solution-proceessable and stable cathode buffer layer is of great importance for the application of PSCs. Here we demonstrate high performance PSCs by employing as-prepared zirconium acetylacetonate (a-ZrAcac) film spin-cast from its ethanol solution as cathode buffer layer. The PSCs based on a low bandgap polymer PBDTBDD as donor and PC60BM as acceptor with a-ZrAcac/Al cathode demonstrated an average power conversion efficiency (PCE) of 8.75% which is significantly improved than that of the devices with traditional Ca/Al cathode. The improved photovoltaic performance is benefitted from the decreased series resistance and enhanced light harvest of the PSCs with the a-ZrAcac/Al cathode. The results indicate that a-ZrAcac is a promising high performance cathode buffer layer for fabricating large area flexible PSCs. PMID:24732976

High-Voltage Polymers for High-Power Supercapacitors. Version 1

DTIC Science & Technology

2006-05-30

affect the supercapacitor’s performance. Subsequently, our efforts focused on fabricating polymers with high oxidation potentials to increase the power...including spin activation with out significant modifications. Electroactive polymers such as polythiophene, polyacetylene, or polyaniline can be...potentials in excess of 2 V for facile polymerization. In the present case, the triaryl ammine functionality of 2 and 3 is oxidized at the low

Negative Electrode For An Alkaline Cell

DOEpatents

Coco, Isabelle; Cocciantelli, Jean-Michel; Villenave, Jean-Jacques

1998-07-14

The present invention concerns a negative electrode for an alkaline cell, comprising a current collector supporting a paste containing an electrochemically active material and a binder, characterized in that said binder is a polymer containing hydrophilic and hydrophobic groups, said polymer being selected from an acrylic homopolymer, copolymer and terpolymer, an unsaturated organic acid copolymer and an unsaturated acid anhydride copolymer.

Layered conductive polymer on nylon membrane templates for high performance, thin-film supercapacitor electrodes

NASA Astrophysics Data System (ADS)

Shi, HaoTian Harvey; Naguib, Hani E.

2016-04-01

Flexible Thin-film Electrochemical Capacitors (ECs) are emerging technology that plays an important role as energy supply for various electronics system for both present era and the future. Intrinsically conductive polymers (ICPs) are promising pseudo-capacitive materials as they feature both good electrical conductivity and high specific capacitance. This study focuses on the construction and characterization of ultra-high surface area porous electrodes based on coating of nano-sized conductive polymer materials on nylon membrane templates. Herein, a novel nano-engineered electrode material based on nylon membranes was presented, which allows the creation of super-capacitor devices that is capable of delivering competitive performance, while maintaining desirable mechanical characteristics. With the formation of a highly conductive network with the polyaniline nano-layer, the electrical conductivity was also increased dramatically to facilitate the charge transfer process. Cyclic voltammetry and specific capacitance results showed promising application of this type of composite materials for future smart textile applications.

Polymer Electrolyte Through Enzyme Catalysis for High Performance Lithium-Ion Batteries

DTIC Science & Technology

1998-10-16

by block number) FIELD GROUP SUB-GROUP Polymer Electrolyte, Solid State, Enzyme Catalysis, Lithium - Ion Battery , Sol Gel, High Conductivity 19...excellent candidates for lithium - ion battery development. Furthermore, the processes used to achieve the final product yield very good mechanical properties...Objectives This research was initiated to investigate synthesis of improved polymer electrolytes for lithium - ion battery applications. The overall

Morphology evolution in high-performance polymer solar cells processed from nonhalogenated solvent

DOE PAGES

Cai, Wanzhu; Liu, Peng; Jin, Yaocheng; ...

2015-05-26

A new processing protocol based on non-halogenated solvent and additive is developed to produce polymer solar cells with power conversion efficiencies better than those processed from commonly used halogenated solvent-additive pair. Morphology studies show that good performance correlates with a finely distributed nanomorphology with a well-defined polymer fibril network structure, which leads to balanced charge transport in device operation.

Effect of alkaline addition on anaerobic sludge digestion with combined pretreatment of alkaline and high pressure homogenization.

PubMed

Fang, Wei; Zhang, Panyue; Zhang, Guangming; Jin, Shuguang; Li, Dongyi; Zhang, Meixia; Xu, Xiangzhe

2014-09-01

To improve anaerobic digestion efficiency, combination pretreatment of alkaline and high pressure homogenization was applied to pretreat sewage sludge. Effect of alkaline dosage on anaerobic sludge digestion was investigated in detail. SCOD of sludge supernatant significantly increased with the alkaline dosage increase after the combined pretreatment because of sludge disintegration. Organics were significantly degraded after the anaerobic digestion, and the maximal SCOD, TCOD and VS removal was 73.5%, 61.3% and 43.5%, respectively. Cumulative biogas production, methane content in biogas and biogas production rate obviously increased with the alkaline dosage increase. Considering both the biogas production and alkaline dosage, the optimal alkaline dosage was selected as 0.04 mol/L. Relationships between biogas production and sludge disintegration showed that the accumulative biogas was mainly enhanced by the sludge disintegration. The methane yield linearly increased with the DDCOD increase as Methane yield (ml/gVS)=4.66 DDCOD-9.69. Copyright © 2014 Elsevier Ltd. All rights reserved.

Use of highly alkaline conditions to improve cost-effectiveness of algal biotechnology.

PubMed

Canon-Rubio, Karen A; Sharp, Christine E; Bergerson, Joule; Strous, Marc; De la Hoz Siegler, Hector

2016-02-01

Phototrophic microorganisms have been proposed as an alternative to capture carbon dioxide (CO2) and to produce biofuels and other valuable products. Low CO2 absorption rates, low volumetric productivities, and inefficient downstream processing, however, currently make algal biotechnology highly energy intensive, expensive, and not economically competitive to produce biofuels. This mini-review summarizes advances made regarding the cultivation of phototrophic microorganisms at highly alkaline conditions, as well as other innovations oriented toward reducing the energy input into the cultivation and processing stages. An evaluation, in terms of energy requirements and energy return on energy invested, is performed for an integrated high-pH, high-alkalinity growth process that uses biofilms. Performance in terms of productivity and expected energy return on energy invested is presented for this process and is compared to previously reported life cycle assessments (LCAs) for systems at near-neutral pH. The cultivation of alkaliphilic phototrophic microorganisms in biofilms is shown to have a significant potential to reduce both energy requirements and capital costs.

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

Thermostable gel polymer electrolyte based on succinonitrile and ionic liquid for high-performance solid-state supercapacitors

NASA Astrophysics Data System (ADS)

Pandey, Gaind P.; Liu, Tao; Hancock, Cody; Li, Yonghui; Sun, Xiuzhi Susan; Li, Jun

2016-10-01

A flexible, free-standing, thermostable gel polymer electrolyte based on plastic crystalline succinonitrile (SN) and ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate (BMImBF4) entrapped in copolymer poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) is prepared and optimized for application in solvent-free solid-state supercapacitors. The synthesized gel polymer electrolyte exhibits a high ionic conductivity over a wide temperature range (from ∼5 × 10-4 S cm-1 at -30 °C up to ∼1.5 × 10-2 S cm-1 at 80 °C) with good electrochemical stability window (-2.9 to 2.5 V). Thermal studies confirm that the SN containing gel polymer electrolyte remains stable in the same gel phase over a wide temperature range from -30 to 90 °C. The electric double layer capacitors (EDLCs) have been fabricated using activated carbon as active materials and new gel polymer electrolytes. Electrochemical performance of the EDLCs is assessed through cyclic voltammetry, galvanostatic charge-discharge cycling and impedance spectroscopy. The EDLC cells with the proper SN-containing gel polymer electrolyte has been found to give high specific capacitance 176 F g-1 at 0.18 A g-1 and 138 F g-1 at 8 A g-1. These solid-state EDLC cells show good cycling stability and the capability to retain ∼80% of the initial capacitance after 10,000 cycles.

Radiation-grafted fluoropolymers soaked with imidazolium-based ionic liquids for high-performance ionic polymer-metal composite actuators.

PubMed

Lee, Jang Yeol; Wang, Hyuck Sik; Yoon, Bye Ri; Han, Man Jae; Jho, Jae Young

2010-11-01

On purpose to develop a polymer actuator with high stability in air-operation as well as large bending displacement, a series of ionic polymer-metal composites (IPMC) was constructed with poly(styrene sulfonate)-grafted fluoropolymers as ionomeric matrix and immidazolium-based ionic liquids (IL) as inner solvent. The prepared IPMC actuators exhibited greatly enhanced bending displacement compared to Nafion-based actuators. The actuators were stable in air-operation, maintaining initial displacement for up to 10(4) cycles or 24 h. Investigating the material parameters and morphology of the IPMCs, high ion exchange capacity of the ionomers resulted in high ion conductivity and robust electrode of IPMC, which synergistically contributed to the high bending performance. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

High performance lignin-acrylonitrile polymer blend materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Naskar, Amit K.; Tran, Chau D.

A polymer blend material comprising: (i) a lignin component having a weight-average molecular weight of up to 1,000,000 g/mol; and (ii) an acrylonitrile-containing copolymer rubber component comprising acrylonitrile units in combination with diene monomer units, and having an acrylonitrile content of at least 20 mol %; wherein said lignin component is present in an amount of at least 5 wt % and up to about 95 wt % by total weight of components (i) and (ii); and said polymer blend material possesses a tensile yield stress of at least 5 MPa, or a tensile stress of at least 5 MPamore » at 10% elongation, or a tensile stress of at least 5 MPa at 100% elongation. Methods for producing the polymer blend, molded forms thereof, and articles thereof, are also described.« less

High-Performance Flexible Solid-State Supercapacitor with an Extended Nanoregime Interface through in Situ Polymer Electrolyte Generation.

PubMed

Anothumakkool, Bihag; Torris A T, Arun; Veeliyath, Sajna; Vijayakumar, Vidyanand; Badiger, Manohar V; Kurungot, Sreekumar

2016-01-20

Here, we report an efficient strategy by which a significantly enhanced electrode-electrolyte interface in an electrode for supercapacitor application could be accomplished by allowing in situ polymer gel electrolyte generation inside the nanopores of the electrodes. This unique and highly efficient strategy could be conceived by judiciously maintaining ultraviolet-triggered polymerization of a monomer mixture in the presence of a high-surface-area porous carbon. The method is very simple and scalable, and a prototype, flexible solid-state supercapacitor could even be demonstrated in an encapsulation-free condition by using the commercial-grade electrodes (thickness = 150 μm, area = 12 cm(2), and mass loading = 7.3 mg/cm(2)). This prototype device shows a capacitance of 130 F/g at a substantially reduced internal resistance of 0.5 Ω and a high capacitance retention of 84% after 32000 cycles. The present system is found to be clearly outperforming a similar system derived by using the conventional polymer electrolyte (PVA-H3PO4 as the electrolyte), which could display a capacitance of only 95 F/g, and this value falls to nearly 50% in just 5000 cycles. The superior performance in the present case is credited primarily to the excellent interface formation of the in situ generated polymer electrolyte inside the nanopores of the electrode. Further, the interpenetrated nature of the polymer also helps the device to show a low electron spin resonance and power rate and, most importantly, excellent shelf-life in the unsealed flexible conditions. Because the nature of the electrode-electrolyte interface is the major performance-determining factor in the case of many electrochemical energy storage/conversion systems, along with the supercapacitors, the developed process can also find applications in preparing electrodes for the devices such as lithium-ion batteries, metal-air batteries, polymer electrolyte membrane fuel cells, etc.

Performance Test on Polymer Waste Form - 12137

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Se Yup

Polymer solidification was attempted to produce stable waste form for the boric acid concentrates and the dewatered spent resins. The polymer mixture was directly injected into the mold or drum which was packed with the boric acid concentrates and the dewatered spent resins, respectively. The waste form was produced by entirely curing the polymer mixture. A series of performance tests was conducted including compressive strength test, water immersion test, leach test, thermal stability test, irradiation stability test and biodegradation stability test for the polymer waste forms. From the results of the performance tests for the polymer waste forms, it ismore » believed that the polymer waste form is very stable and can satisfy the acceptance criteria for permanent disposal. At present, performance tests with full scale polymer waste forms are being carried out in order to obtain qualification certificate by the regulatory institute in Korea. Polymer waste forms were prepared with the surrogate of boric acid concentrates and the surrogate of spent ion exchange resins respectively. Waste forms were also made in lab scale and in full scale. Lab. scale waste forms were directly subjected to a series of the performance tests. In the case of full scale waste form, the test specimens for the performance test were taken from a part of waste form by coring. A series of performance tests was conducted including compressive strength test, thermal stability test, irradiation stability test and biodegradation stability test, water immersion test, leach test, and free standing water for the polymer waste forms. In addition, a fire resistance test was performed on the waste forms by the requirement of the regulatory institute in Korea. Every polymer waste forms containing the boric acid concentrates and the spent ion exchange resins had exhibited excellent structural integrity of more than 27.58 MPa (4,000 psi) of compressive strength. On thermal stability testing

Towards highly stable polymer electronics (Conference Presentation)

NASA Astrophysics Data System (ADS)

Nikolka, Mark; Nasrallah, Iyad; Broch, Katharina; Sadhanala, Aditya; Hurhangee, Michael; McCulloch, Iain; Sirringhaus, Henning

2016-11-01

Due to their ease of processing, organic semiconductors are promising candidates for applications in high performance flexible displays and fast organic electronic circuitry. Recently, a lot of advances have been made on organic semiconductors exhibiting surprisingly high performance and carrier mobilities exceeding those of amorphous silicon. However, there remain significant concerns about their operational and environmental stability, particularly in the context of applications that require a very high level of threshold voltage stability, such as active-matrix addressing of organic light-emitting diode (OLED) displays. Here, we report a novel technique for dramatically improving the operational stress stability, performance and uniformity of high mobility polymer field-effect transistors by the addition of specific small molecule additives to the polymer semiconductor film. We demonstrate for the first time polymer FETs that exhibit stable threshold voltages with threshold voltage shifts of less than 1V when subjected to a constant current operational stress for 1 day under conditions that are representative for applications in OLED active matrix displays. The approach constitutes in our view a technological breakthrough; it also makes the device characteristics independent of the atmosphere in which it is operated, causes a significant reduction in contact resistance and significantly improves device uniformity. We will discuss in detail the microscopic mechanism by which the molecular additives lead to this significant improvement in device performance and stability.

Benzene Adsorption - A Significant Inhibitor for the Hydrogen Oxidation Reaction in Alkaline Conditions

DOE PAGES

Gonzales, Ivana; Chung, Hoon Taek; Kim, Yu Seung

2017-09-25

Slow hydrogen oxidation reaction (HOR) kinetics on Pt under alkaline conditions is a significant technical barrier for the development of high-performance hydroxide exchange membrane fuel cells. Here we report that benzene adsorption on Pt is a major factor responsible for the sluggish HOR. Furthermore, we demonstrate that bimetallic catalysts, such as PtMo/C, PtNi/C, and PtRu/C, can reduce the adsorption of benzene and thereby improve HOR activity. In particular, the HOR voltammogram of PtRu/C in 0.1 M benzyl ammonium showed minimal benzene adsorption. Density functional theory calculations indicate that the adsorption of benzyl ammonium on the bimetallic PtRu is endergonic formore » all four possible orientations of the cation, which explains the significantly better HOR activity observed for the bimetallic catalysts. In conclusion, the new HOR inhibition mechanism described here provides insights for the design of future polymer electrolytes and electrocatalysts for better-performing polymer membrane-based fuel cells.« less

Polymer/boron nitride nanocomposite materials for superior thermal transport performance.

PubMed

Song, Wei-Li; Wang, Ping; Cao, Li; Anderson, Ankoma; Meziani, Mohammed J; Farr, Andrew J; Sun, Ya-Ping

2012-06-25

Boron nitride nanosheets were dispersed in polymers to give composite films with excellent thermal transport performances approaching the record values found in polymer/graphene nanocomposites. Similarly high performance at lower BN loadings was achieved by aligning the nanosheets in poly(vinyl alcohol) matrix by simple mechanical stretching (see picture). Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Honeycomb-shaped coordination polymers based on the self-assembly of long flexible ligands and alkaline-earth ions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lian, Chen; Liu, Liu; Guo, Xu

2016-01-15

Two novel coordination polymers, namely, [Ca(NCP){sub 2}]{sub ∞} (I) and [Sr(NCP){sub 2}]{sub ∞} (II) were synthesized under hydrothermal conditions based on 2-(4-carboxyphenyl)imidazo(4,5-f)-(1,10)phenanthroline (HNCP) and characterized by elemental analysis, infrared spectrometry, X-ray powder diffraction and single crystal X-ray diffraction. Findings indicate that I and II are isomorphous and isostructural, containing the unit of M(NCP{sup −}){sub 4} (M=Ca(II) and Sr(II)), based on which to assemble into three-dimensional (3D) porous 4-fold interpenetration honeycomb-shaped neutral coordination polymers (CPs). Between the adjacent lamellar structures in I and II, there exist π–π interactions between the pyridine rings belonging to phenanthroline of NCP{sup −} which stabilize themore » frameworks. Both I and II display stronger fluorescence emissions as well as high thermal stability. - Graphical abstract: One-dimensional nanotubular channels with the cross dimension of 37.1959(20)×23.6141(11)Å{sup 2} in the three-dimensional honeycomb-shaped coordination network of II are observed. The topological analysis of II indicates that there exists a typical diamond framework possessing large adamantanoid cages, which containing four cyclohexane-shaped patterns in chair conformations. - Highlights: • Two isomorphous and isostructural coordination polymers based on flexible ligand and two alkaline-earth metal salts have been synthesized and characterized. • Structural analysis indicates that I and II are assembled into 3D porous honeycomb-shaped metal-organic frameworks. • Both I and II display stronger fluorescence emissions and higher thermal stability.« less

A tough performance simultaneous semi-interpenetrating polymer network

NASA Technical Reports Server (NTRS)

Pater, Ruth H. (Inventor)

1989-01-01

A semi-interpenetrating polyimide (semi-IPN) network and methods for making and using the same are disclosed. The semi-IPN system comprises a high performance thermosetting polyimide having an acetylene-terminated group acting as a crosslinking site and a high performance linear thermoplastic polyimide. The polymer is made by combining low viscosity precursors and low molecular weight polymers of the thermosetting and thermoplastic polyimides and allowing them to react in the immediate presence of each other to form a simultaneous semi-interpenetrating polyimide network. Provided is a high temperature system having significantly improved processability and damage tolerance while maintaining excellent thermo-oxidative stability, mechanical properties and resistance to humidity, when compared with the commercial high temperature resin, Thermid 600. This material is particularly adapted for use as a molding, adhesive and advanced composite matrix for aerospace structural and electronic applications.

Post-exercise ingestion of a unique, high molecular weight glucose polymer solution improves performance during a subsequent bout of cycling exercise.

PubMed

Stephens, Francis B; Roig, Marc; Armstrong, Gerald; Greenhaff, Paul L

2008-01-15

The aim of the present study was to determine the effect of post-exercise ingestion of a unique, high molecular weight glucose polymer solution, known to augment gastric emptying and post-exercise muscle glycogen re-synthesis, on performance during a subsequent bout of intense exercise. On three randomized visits, eight healthy men cycled to exhaustion at 73.0% (s = 1.3) maximal oxygen uptake (90 min, s = 15). Immediately after this, participants consumed a one-litre solution containing sugar-free flavoured water (control), 100 g of a low molecular weight glucose polymer or 100 g of a very high molecular weight glucose polymer, and rested on a bed for 2 h. After recovery, a 15-min time-trial was performed on a cycle ergometer, during which work output was determined. Post-exercise ingestion of the very high molecular weight glucose polymer solution resulted in faster and greater increases in blood glucose (P < 0.001) and serum insulin (P < 0.01) concentrations than the low molecular weight glucose polymer solution, and greater work output during the 15-min time-trial (164.1 kJ, s = 21.1) than both the sugar-free flavoured water (137.5 kJ, s = 24.2; P < 0.05) and the low molecular weight glucose polymer (149.4 kJ, s = 21.8; P < 0.05) solutions. These findings could be of practical importance for athletes wishing to optimize performance by facilitating rapid re-synthesis of the muscle glycogen store during recovery following prolonged sub-maximal exercise.

Advances in the high performance polymer electrolyte membranes for fuel cells.

PubMed

Zhang, Hongwei; Shen, Pei Kang

2012-03-21

This critical review tersely and concisely reviews the recent development of the polymer electrolyte membranes and the relationship between their properties and affecting factors like operation temperature. In the first section, the advantages and shortcomings of the corresponding polymer electrolyte membrane fuel cells are analyzed. Then, the limitations of Nafion membranes and their alternatives to large-scale commercial applications are discussed. Secondly, the concepts and approaches of the alternative proton exchange membranes for low temperature and high temperature fuel cells are described. The highlights of the current scientific achievements are given for various aspects of approaches. Thirdly, the progress of anion exchange membranes is presented. Finally, the perspectives of future trends on polymer electrolyte membranes for different applications are commented on (400 references).

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.

Alkaline flooding for enhanced oil recovery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gittler, W.E.

1983-09-01

There are over 12 active projects of varying size using one of 3 major types of alkaline agents. These include sodium silicate, caustic soda, and soda ash. Among the largest pilots currently is the THUMS project in the Wilmington field, California. Plans called for the injection of a 4% weight concentration of sodium orthosilicate over a 60% PV. Through the first 3 yr, over 27 million bbl of chemicals have been injected. Gulf Oil is operating several alkaline floods, one of which is located off shore in the Quarantine Bay field, Louisiana. In this pilot, sodium hydroxide in a weightmore » concentration of 5 to 12% is being injected. Belco Petroleum Corp. has reported that their pilot operating in the Isenhour Unit in Wyoming is using a .5% weight concentration of soda ash in conjunction with a polymer. Other uses for alkaline agents in chemical flooding include the use of silicate as a preflush or sacrificial agent in micellar/polymer and surfactant recovery systems. In addition, caustic has been tested in the surface-mixed caustic emulsion process while orthosilicate has been tested in a recovery method known as mobility-controlled caustic floods.« less

Block copolymers for alkaline fuel cell membrane materials

NASA Astrophysics Data System (ADS)

Li, Yifan

Alkaline fuel cells (AFCs) using anion exchange membranes (AEMs) as electrolyte have recently received considerable attention. AFCs offer some advantages over proton exchange membrane fuel cells, including the potential of non-noble metal (e.g. nickel, silver) catalyst on the cathode, which can dramatically lower the fuel cell cost. The main drawback of traditional AFCs is the use of liquid electrolyte (e.g. aqueous potassium hydroxide), which can result in the formation of carbonate precipitates by reaction with carbon dioxide. AEMs with tethered cations can overcome the precipitates formed in traditional AFCs. Our current research focuses on developing different polymer systems (blend, block, grafted, and crosslinked polymers) in order to understand alkaline fuel cell membrane in many aspects and design optimized anion exchange membranes with better alkaline stability, mechanical integrity and ionic conductivity. A number of distinct materials have been produced and characterized. A polymer blend system comprised of poly(vinylbenzyl chloride)-b-polystyrene (PVBC-b-PS) diblock copolymer, prepared by nitroxide mediated polymerization (NMP), with poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) or brominated PPO was studied for conversion into a blend membrane for AEM. The formation of a miscible blend matrix improved mechanical properties while maintaining high ionic conductivity through formation of phase separated ionic domains. Using anionic polymerization, a polyethylene based block copolymer was designed where the polyethylene-based block copolymer formed bicontinuous morphological structures to enhance the hydroxide conductivity (up to 94 mS/cm at 80 °C) while excellent mechanical properties (strain up to 205%) of the polyethylene block copolymer membrane was observed. A polymer system was designed and characterized with monomethoxy polyethylene glycol (mPEG) as a hydrophilic polymer grafted through substitution of pendent benzyl chloride groups of a PVBC

Polymer Day: Outreach Experiments for High School Students

ERIC Educational Resources Information Center

Ting, Jeffrey M.; Ricarte, Ralm G.; Schneiderman, Deborah K.; Saba, Stacey A.; Jiang, Yaming; Hillmyer, Marc A.; Bates, Frank S.; Reineke, Theresa M.; Macosko, Christopher W.; Lodge, Timothy P.

2017-01-01

We present a collection of hands-on experiments that collectively teach precollege students fundamental concepts of polymer synthesis and characterization. These interactive experiments are performed annually as part of an all-day outreach event for high school students that can inform the development of ongoing polymer education efforts in a…

Validation of a new menstrual pictogram (superabsorbent polymer-c version) for use with ultraslim towels that contain superabsorbent polymers.

PubMed

Magnay, Julia L; Nevatte, Tracy M; O'Brien, Shaughn; Gerlinger, Christoph; Seitz, Christian

2014-02-01

To validate the menstrual pictogram (superabsorbent polymer-c version) for Always Ultra-slim feminine towels containing superabsorbent polymers. Prospective, multicenter, evaluator-blinded study. Three gynecology research clinics in the United Kingdom. Women with self-perceived light, normal, or heavy menstrual periods who had not previously used a graphical method to assess their menstrual loss. One hundred twenty-two women were asked to complete the menstrual pictogram throughout two menstrual periods and collect their feminine towels for measurements of menstrual blood loss (MBL) by the alkaline hematin method and total menstrual fluid loss (MFL) by fluid weight. Agreement of menstrual pictogram MBL and MFL scores with alkaline hematin and towel weight, respectively. The percentage blood fraction was determined at various volumes of menstrual discharge. Alkaline hematin and fluid weight were highly correlated (r = .97). However, the percentage blood fraction progressively increased with total MFL and MBL score. After correction for this incremental rise in blood fraction, the menstrual pictogram gave a sensitivity of 82% and a specificity of 92% for a diagnosis of heavy menstrual bleeding. The menstrual pictogram (superabsorbent polymer-c version) provides a simple means of measuring MBL in the clinical setting. Copyright © 2014 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

Well-Balanced Ambipolar Conjugated Polymers Featuring Mild Glass Transition Temperatures Toward High-Performance Flexible Field-Effect Transistors.

PubMed

Shi, Keli; Zhang, Weifeng; Gao, Dong; Zhang, Shiying; Lin, Zuzhang; Zou, Ye; Wang, Liping; Yu, Gui

2018-03-01

Conjugated polymers, which can be fabricated by simple processing techniques and possess excellent electrical performance, are key to the fabrication of flexible polymer field-effect transistors (PFETs) and integrated circuits. Herein, two ambipolar conjugated polymers based on (3E,7E)-3,7-bis(2-oxo-1H-pyrrolo[2,3-b]pyridin-3(2H)-ylidene)benzo[1,2-b:4,5-b']difuran-2,6(3H,7H)-dione and dithienylbenzothiadiazole units, namely PNBDOPV-DTBT and PNBDOPV-DTF2BT, are developed. Both copolymers possess almost planar conjugated backbone conformations and suitable highest occupied molecular orbital (HOMO)/lowest unoccupied molecular orbital (LUMO) energy levels (-5.64/-4.38 eV for PNBDOPV-DTBT and -5.79/-4.48 eV for PNBDOPV-DTF2BT). Note that PNBDOPV-DTBT has a glass transition temperature (140 °C) lower than the deformation temperature of polyethylene terephthalate (PET), meaning well-ordered molecular packing can be obtained on PET substrate before its deformation in mild thermal annealing process. Flexible PFETs based on PNBDOPV-DTBT fabricated on PET substrates exhibit high and well-balanced hole/electron mobilities of 4.68/4.72 cm 2 V -1 s -1 under ambient conditions. After the further modification of Au source/drain electrodes with 1-octanethiol self-assembled monolayers, impressively high and well-balanced hole/electron mobilities up to 5.97/7.07 cm 2 V -1 s -1 are achieved in the flexible PFETs. Meanwhile, flexible complementary-like inverters based on PNBDOPV-DTBT on PET substrate also afford a much high gain of 148. The device performances of both the PFETs and inverters are among the highest values for ambipolar conjugated polymers reported to date. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Cation-containing Polymer Anion Exchange Membrane based on Poly(norbornene)

NASA Astrophysics Data System (ADS)

Beyer, Frederick; Price, Samuel; Ren, Xiaoming; Savage, Alice

Cation-containing polymers are being studied widely for use as anion exchange membranes (AEMs) in alkaline fuel cells (AFCs) because AEMs offer a number of potential benefits including allowing a solid state device and elimination of the carbonate poisoning problem. The successful AEM will combine high performance from several orthogonal properties, having robust mechanical strength even when wet, high hydroxide conductivity, and the high chemical stability required for long device lifetimes. In this study, we have synthesized a model cationic polymer that combines three of the key advantages of Nafion. The polymer backbone based on semicrystalline atactic poly(norbornene) offers good mechanical properties. A flexible, ether-based tether between the backbone and fixed cation charged species (quaternary ammonium) should provide the low-Tg, hydrophilic environment required to facilitate OH- transport. Finally, methyl groups have been added at the beta position relative to the quaternary ammonium cation to prevent Hoffman elimination, one mechanism by which AEMs are neutralized in a high pH environment. In this poster, we will present our findings on mechanical properties, morphology, charge transport, and chemical stability of this material.

Alkaline Earth Core Level Photoemission Spectroscopy of High-Temperature Superconductors

NASA Technical Reports Server (NTRS)

Vasquez, R.

1993-01-01

This paper examines photoemission measurements of the alkaline Earth core levels of high-temperature superconductors and related materials, models that seek to explain the large negative shifts observed relative to the corresponding alkaline Earth metals, and the effect of lattice site disorder on the core level spectra and the presence or absence of intrinsic surface peaks.

High-performance 193-nm photoresist materials based on ROMA polymers: sub-90-nm contact hole application with resist reflow

NASA Astrophysics Data System (ADS)

Joo, Hyun S.; Seo, Dong C.; Kim, Chang M.; Lim, Young T.; Cho, Seong D.; Lee, Jong B.; Song, Ji Y.; Kim, Kyoung M.; Park, Joo H.; Jung, Jae Chang; Shin, Ki S.; Bok, Cheol Kyu; Moon, Seung C.

2004-05-01

There are numerous methods being explored by lithographers to achieve the patterning of sub-90nm contact hole features. Regarding optical impact on contact imaging, various optical extension techniques such as assist features, focus drilling, phase shift masks, and off-axis illumination are being employed to improve the aerial image. One possible option for improving of the process window in contact hole patterning is resist reflow. We have already reported the resist using a ring opened polymer of maleic anhydride unit(ROMA) during the past two years in this conference. It has several good properties such as UV transmittance, PED stability, solubility and storage stability. The resist using ROMA polymer as a matrix resin showed a good lithographic performance at C/H pattern and one of the best characteristics in a ROMA polymer is the property of thermal shrinkage. It has a specific glass transition temperature(Tg) each polymers, so they made a applying of resist reflow technique to print sub-90nm C/H possible. Recently, we have researched about advanced ROMA polymer(ROMA II), which is composed of cycloolefine derivatives with existing ROMA type polymer(ROMA I), for dry etch resistance increasing, high resolution, and good thermal shrinkage property. In this paper, we will present the structure, thermal shrinkage properties, Tg control, material properties for ROMA II polymer and will show characteristics, the lithographic performance for iso and dense C/H applications of the resist using ROMA II polymer. In addition, we will discuss resist reflow data gained at C/H profile of sub-90nm sizes, which has good process window.

Potential approaches to the spectroscopic characterization of high performance polymers exposed to energetic protons and heavy ions

NASA Technical Reports Server (NTRS)

Suleman, Naushadalli K.

1991-01-01

A potential limitation to human activity on the lunar surface or in deep space is the exposure of the crew to unacceptably high levels of penetrating space radiations. The radiations of most concerns for such missions are high-energy protons emitted during solar flares, and galactic cosmic rays which are high-energy ions ranging from protons to iron. The development of materials for effective shielding from energetic space radiations will clearly require a greater understanding of the underlying mechanisms of radiation-induced damage in bulk materials. This can be accomplished in part by the detailed spectroscopic characterization of bulk materials that were exposed to simulated space radiations. An experimental data base thus created can then be used in conjunction with existing radiation transport codes in the design and fabrication of effective radiation shielding materials. Electron Paramagnetic Resonance Spectroscopy was proven very useful in elucidating radiation effects in polymers (high performance polymers are often an important components of structural composites).

Development of high-performing semiconducting polymers for organic electrochemical transistors (Conference Presentation)

NASA Astrophysics Data System (ADS)

Nielsen, Christian

2016-11-01

The organic electrochemical transistor (OECT), capable of amplifying small electrical signals in an aqueous environment, is an ideal device to utilize in organic bioelectronic applications involving for example neural interfacing and diagnostics. Currently, most OECTs are fabricated with commercially available conducting poly(3,4-ethylenedioxythiophene)-based suspensions such as PEDOT:PSS and are therefore operated in depletion mode giving rise to devices that are permanently on with non-optimal operational voltage. With the aim to develop and utilize efficient accumulation mode OECT devices, we discuss here our recent results regarding the design, synthesis and performance of novel intrinsic semiconducting polymers. Covering key aspects such as ion and charge transport in the bulk semiconductor and operational voltage and stability of the materials and devices, we have elucidated important structure-property relationships. We illustrate the improvements this approach has afforded in the development of high performance accumulation mode OECT materials.

Understanding the role of different conductive polymers in improving the nanostructured sulfur cathode performance.

PubMed

Li, Weiyang; Zhang, Qianfan; Zheng, Guangyuan; Seh, Zhi Wei; Yao, Hongbin; Cui, Yi

2013-01-01

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

Polymer as an Additive in the Emitting Layer for High-Performance Quantum Dot Light-Emitting Diodes.

PubMed

Liang, Feng; Liu, Yuan; Hu, Yun; Shi, Ying-Li; Liu, Yu-Qiang; Wang, Zhao-Kui; Wang, Xue-Dong; Sun, Bao-Quan; Liao, Liang-Sheng

2017-06-14

A facile but effective method is proposed to improve the performance of quantum dot light-emitting diodes (QLEDs) by incorporating a polymer, poly(9-vinlycarbazole) (PVK), as an additive into the CdSe/CdS/ZnS quantum dot (QD) emitting layer (EML). It is found that the charge balance of the device with the PVK-added EML was greatly improved. In addition, the film morphology of the hole-transporting layer (HTL) which is adjacent to the EML, is substantially improved. The surface roughness of the HTL is reduced from 5.87 to 1.38 nm, which promises a good contact between the HTL and the EML, resulting in low leakage current. With the improved charge balance and morphology, a maximum external quantum efficiency (EQE) of 16.8% corresponding to the current efficiency of 19.0 cd/A is achievable in the red QLEDs. The EQE is 1.6 times as high as that (10.5%) of the reference QLED, comprising a pure QD EML. This work demonstrates that incorporating some polymer molecules into the QD EML as additives could be a facile route toward high-performance QLEDs.

An alkaline active xylanase: insights into mechanisms of high pH catalytic adaptation.

PubMed

Mamo, Gashaw; Thunnissen, Marjolein; Hatti-Kaul, Rajni; Mattiasson, Bo

2009-09-01

The alkaliphilic bacterium, Bacillus halodurans S7, produces an alkaline active xylanase (EC 3.2.1.8), which differs from many other xylanases in being operationally stable under alkaline conditions as well as at elevated temperature. Compared to non-alkaline active xylanases, this enzyme has a high percent composition of acidic amino acids which results in high ratio of negatively to positively charged residues. A positive correlation was observed between the charge ratio and the pH optima of xylanases. The recombinant xylanase was crystallized using a hanging drop diffusion method. The crystals belong to the space group P2(1)2(1)2(1) and the structure was determined at a resolution of 2.1 A. The enzyme has the common eight-fold TIM-barrel structure of family 10 xylanases; however, unlike non-alkaline active xylanases, it has a highly negatively charged surface and a deeper active site cleft. Mutational analysis of non-conserved amino acids which are close to the acid/base residue has shown that Val169, Ile170 and Asp171 are important to hydrolyze xylan at high pH. Unlike the wild type xylanase which has optimum pH at 9-9.5, the triple mutant xylanase (V169A, I170F and D171N), which was constructed using sequence information of alkaline sensitive xylanses was optimally active around pH 7. Compared to non-alkaline active xylanases, the alkaline active xylanases have highly acidic surfaces and fewer solvent exposed alkali labile residues. Based on these results obtained from sequence, structural and mutational analysis, the possible mechanisms of high pH stability and catalysis are discussed. This will provide useful information to understand the mechanism of high pH adaptation and engineering of enzymes that can be operationally stable at high pH.

Spontaneously formed high-performance charge-transport layers of organic single-crystal semiconductors on precisely synthesized insulating polymers

NASA Astrophysics Data System (ADS)

Makita, Tatsuyuki; Sasaki, Masayuki; Annaka, Tatsuro; Sasaki, Mari; Matsui, Hiroyuki; Mitsui, Chikahiko; Kumagai, Shohei; Watanabe, Shun; Hayakawa, Teruaki; Okamoto, Toshihiro; Takeya, Jun

2017-04-01

Charge-transporting semiconductor layers with high carrier mobility and low trap-density, desired for high-performance organic transistors, are spontaneously formed as a result of thermodynamic phase separation from a blend of π-conjugated small molecules and precisely synthesized insulating polymers dissolved in an aromatic solvent. A crystal film grows continuously to the size of centimeters, with the critical conditions of temperature, concentrations, and atmosphere. It turns out that the molecular weight of the insulating polymers plays an essential role in stable film growth and interfacial homogeneity at the phase separation boundary. Fabricating the transistor devices directly at the semiconductor-insulator boundaries, we demonstrate that the mixture of 3,11-didecyldinaphtho[2,3-d:2',3'-d']benzo[1,2-b:4,5-b']dithiophene and poly(methyl methacrylate) with the optimized weight-average molecular weight shows excellent device performances. The spontaneous phase separation with a one-step fabrication process leads to a high mobility up to 10 cm2 V-1 s-1 and a low subthreshold swing of 0.25 V dec-1 even without any surface treatment such as self-assembled monolayer modifications on oxide gate insulators.

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.

Polymer Ni-MH battery based on PEO-PVA-KOH polymer electrolyte

NASA Astrophysics Data System (ADS)

Yang, Chun-Chen

An alkaline polymer electrolyte film has been prepared by a solvent-casting method. Poly(vinyl alcohol), PVA is added to improve the ionic conductivity of the electrolyte. The ionic conductivity increases from 10 -7 to 10 -2 S cm -1 at room temperature when the weight percent ratio of poly(ethylene oxide), PEO to PVA is increased from 10:0 to 5:5. The activation energy of the ionic conductivity for the PEO-PVA-KOH polymer electrolyte is 3-8 kJ mol -1. The properties of the electrolyte film are characterized by a wide variety of techniques and it is found that the film exhibits good mechanical stability and high ionic conductivity at room temperature. The application of such electrolyte films to nickel-metal-hydride (Ni-MH) batteries is examined and the electrochemical characteristics of a polymer Ni-MH battery are obtained.

Cation exchange properties of zeolites in hyper alkaline aqueous media.

PubMed

Van Tendeloo, Leen; de Blochouse, Benny; Dom, Dirk; Vancluysen, Jacqueline; Snellings, Ruben; Martens, Johan A; Kirschhock, Christine E A; Maes, André; Breynaert, Eric

2015-02-03

Construction of multibarrier concrete based waste disposal sites and management of alkaline mine drainage water requires cation exchangers combining excellent sorption properties with a high stability and predictable performance in hyper alkaline media. Though highly selective organic cation exchange resins have been developed for most pollutants, they can serve as a growth medium for bacterial proliferation, impairing their long-term stability and introducing unpredictable parameters into the evolution of the system. Zeolites represent a family of inorganic cation exchangers, which naturally occur in hyper alkaline conditions and cannot serve as an electron donor or carbon source for microbial proliferation. Despite their successful application as industrial cation exchangers under near neutral conditions, their performance in hyper alkaline, saline water remains highly undocumented. Using Cs(+) as a benchmark element, this study aims to assess the long-term cation exchange performance of zeolites in concrete derived aqueous solutions. Comparison of their exchange properties in alkaline media with data obtained in near neutral solutions demonstrated that the cation exchange selectivity remains unaffected by the increased hydroxyl concentration; the cation exchange capacity did however show an unexpected increase in hyper alkaline media.

Recent progress of high performance polymer OLED and OPV materials for organic printed electronics.

PubMed

Sekine, Chizu; Tsubata, Yoshiaki; Yamada, Takeshi; Kitano, Makoto; Doi, Shuji

2014-06-01

The development of organic printed electronics has been expanding to a variety of applications and is expected to bring innovations to our future life. Along with this trend, high performance organic materials with cost-efficient fabrication processes and specific features such as thin, light weight, bendable, and low power consumption are required. A variety of organic materials have been investigated in the development of this field. The basic guidelines for material design and the recent progress of polymer-based organic light-emitting diodes (OLEDs) and organic photovoltaic cells (OPVs) are reported.

Recent progress of high performance polymer OLED and OPV materials for organic printed electronics

PubMed Central

Sekine, Chizu; Tsubata, Yoshiaki; Yamada, Takeshi; Kitano, Makoto; Doi, Shuji

2014-01-01

The development of organic printed electronics has been expanding to a variety of applications and is expected to bring innovations to our future life. Along with this trend, high performance organic materials with cost-efficient fabrication processes and specific features such as thin, light weight, bendable, and low power consumption are required. A variety of organic materials have been investigated in the development of this field. The basic guidelines for material design and the recent progress of polymer-based organic light-emitting diodes (OLEDs) and organic photovoltaic cells (OPVs) are reported. PMID:27877671

Recent progress of high performance polymer OLED and OPV materials for organic printed electronics

NASA Astrophysics Data System (ADS)

Sekine, Chizu; Tsubata, Yoshiaki; Yamada, Takeshi; Kitano, Makoto; Doi, Shuji

2014-06-01

The development of organic printed electronics has been expanding to a variety of applications and is expected to bring innovations to our future life. Along with this trend, high performance organic materials with cost-efficient fabrication processes and specific features such as thin, light weight, bendable, and low power consumption are required. A variety of organic materials have been investigated in the development of this field. The basic guidelines for material design and the recent progress of polymer-based organic light-emitting diodes (OLEDs) and organic photovoltaic cells (OPVs) are reported.

All-solid-state Al-air batteries with polymer alkaline gel electrolyte

NASA Astrophysics Data System (ADS)

Zhang, Zhao; Zuo, Chuncheng; Liu, Zihui; Yu, Ying; Zuo, Yuxin; Song, Yu

2014-04-01

Aluminum-air (Al-air) battery is one of the most promising candidates for next-generation energy storage systems because of its high capacity and energy density, and abundance. The polyacrylic acid (PAA)-based alkaline gel electrolyte is used in all-solid-state Al-air batteries instead of aqueous electrolytes to prevent leakage. The optimal gel electrolyte exhibits an ionic conductivity of 460 mS cm-1, which is close to that of aqueous electrolytes. The Al-air battery peak capacity and energy density considering only Al can reach 1166 mAh g-1-Al and 1230 mWh g-1-Al, respectively, during constant current discharge. The battery prototype also exhibits a high power density of 91.13 mW cm-2. For the battery is a laminated structure, area densities of 29.2 mAh cm-2 and 30.8 mWh cm-2 are presented to appraise the performance of the whole cell. A novel design to inhibit anodic corrosion is proposed by separating the Al anode from the gel electrolyte when not in use, thereby effectively maintaining the available capacity of the battery.

Synthesis and characterization of high performing Fe-N-C catalyst for oxygen reduction reaction (ORR) in Alkaline Exchange Membrane Fuel Cells

NASA Astrophysics Data System (ADS)

Hossen, Md Mosaddek; Artyushkova, Kateryna; Atanassov, Plamen; Serov, Alexey

2018-01-01

In this article, three different Fe-N-C oxygen reduction reaction (ORR) catalysts derived from different organic molecules i.e. Fe-NMG, Fe-NMP, Fe-MBZ have been synthesized, characterized by physical-chemical methods and studied in the reaction of oxygen reduction (ORR). It is found that Fe-NMG shows higher ORR performance than Fe-NMP and Fe-MBZ, by both rotating ring disk electrode (RRDE) and fuel cell tests. From characterization and surface analysis, it can be explained that the presence of higher amount of surface oxides and pyridinic nitrogen is the main reason for better performance towards ORR in alkaline media. To achieve the highest performance in alkaline exchange membrane fuel cell (AEMFC), the optimization of catalyst layer composition using various concentrations of ionomer (Tokuyama, AS4) was performed. At the optimum cathode layer configuration utilizing Fe-NMG produces the peak power density of 218 mWcm-2, which is one of the highest values presented in the open literature.

Vacuum-integrated electrospray deposition for highly reliable polymer thin film.

PubMed

Park, Soohyung; Lee, Younjoo; Yi, Yeonjin

2012-10-01

Vacuum electrospray deposition (ESD) equipment was designed to prepare polymer thin films. The polymer solution can be injected directly into vacuum system through multi-stage pumping line, so that the solvent residues and ambient contaminants are highly reduced. To test the performance of ESD system, we fabricated organic photovoltaic cells (OPVCs) by injecting polymer solution directly onto the substrate inside a high vacuum chamber. The OPVC fabricated has the structure of Al∕P3HT:PCBM∕PEDOT:PSS∕ITO and was optimized by varying the speed of solution injection and concentration of the solution. The power conversion efficiency (PCE) of the optimized OPVC is 3.14% under AM 1.5G irradiation without any buffer layer at the cathode side. To test the advantages of the vacuum ESD, we exposed the device to atmosphere between the deposition steps of the active layer and cathode. This showed that the PCE of the vacuum processed device is 24% higher than that of the air exposed device and confirms the advantages of the vacuum prepared polymer film for high performance devices.

"Double-Cable" Conjugated Polymers with Linear Backbone toward High Quantum Efficiencies in Single-Component Polymer Solar Cells.

PubMed

Feng, Guitao; Li, Junyu; Colberts, Fallon J M; Li, Mengmeng; Zhang, Jianqi; Yang, Fan; Jin, Yingzhi; Zhang, Fengling; Janssen, René A J; Li, Cheng; Li, Weiwei

2017-12-27

A series of "double-cable" conjugated polymers were developed for application in efficient single-component polymer solar cells, in which high quantum efficiencies could be achieved due to the optimized nanophase separation between donor and acceptor parts. The new double-cable polymers contain electron-donating poly(benzodithiophene) (BDT) as linear conjugated backbone for hole transport and pendant electron-deficient perylene bisimide (PBI) units for electron transport, connected via a dodecyl linker. Sulfur and fluorine substituents were introduced to tune the energy levels and crystallinity of the conjugated polymers. The double-cable polymers adopt a "face-on" orientation in which the conjugated BDT backbone and the pendant PBI units have a preferential π-π stacking direction perpendicular to the substrate, favorable for interchain charge transport normal to the plane. The linear conjugated backbone acts as a scaffold for the crystallization of the PBI groups, to provide a double-cable nanophase separation of donor and acceptor phases. The optimized nanophase separation enables efficient exciton dissociation as well as charge transport as evidenced from the high-up to 80%-internal quantum efficiency for photon-to-electron conversion. In single-component organic solar cells, the double-cable polymers provide power conversion efficiency up to 4.18%. This is one of the highest performances in single-component organic solar cells. The nanophase-separated design can likely be used to achieve high-performance single-component organic solar cells.

Systematic Analysis of Polymer Molecular Weight Influence on the Organic Photovoltaic Performance.

PubMed

Katsouras, Athanasios; Gasparini, Nicola; Koulogiannis, Chrysanthos; Spanos, Michael; Ameri, Tayebeh; Brabec, Christoph J; Chochos, Christos L; Avgeropoulos, Apostolos

2015-10-01

The molecular weight of an electron donor-conjugated polymer is as essential as other well-known parameters in the chemical structure of the polymer, such as length and the nature of any side groups (alkyl chains) positioned on the polymeric backbone, as well as their placement, relative strength, the ratio of the donor and acceptor moieties in the backbone of donor-acceptor (D-A)-conjugated polymers, and the arrangement of their energy levels for organic photovoltaic performance. Finding the "optimal" molecular weight for a specific conjugated polymer is an important aspect for the development of novel photovoltaic polymers. Therefore, it is evident that the chemistry of functional conjugated polymers faces major challenges and materials have to adopt a broad range of specifications in order to be established for high photovoltaic performance. In this review, the approaches followed for enhancing the molecular weight of electron-donor polymers are presented in detail, as well as how this influences the optoelectronic properties, charge transport properties, structural conformation, morphology, and the photovoltaic performance of the active layer. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Structural Polymer-Based Carbon Nanotube Composite Fibers: Understanding the Processing–Structure–Performance Relationship

PubMed Central

Song, Kenan; Zhang, Yiying; Meng, Jiangsha; Green, Emily C.; Tajaddod, Navid; Li, Heng; Minus, Marilyn L.

2013-01-01

Among the many potential applications of carbon nanotubes (CNT), its usage to strengthen polymers has been paid considerable attention due to the exceptional stiffness, excellent strength, and the low density of CNT. This has provided numerous opportunities for the invention of new material systems for applications requiring high strength and high modulus. Precise control over processing factors, including preserving intact CNT structure, uniform dispersion of CNT within the polymer matrix, effective filler–matrix interfacial interactions, and alignment/orientation of polymer chains/CNT, contribute to the composite fibers’ superior properties. For this reason, fabrication methods play an important role in determining the composite fibers’ microstructure and ultimate mechanical behavior. The current state-of-the-art polymer/CNT high-performance composite fibers, especially in regards to processing–structure–performance, are reviewed in this contribution. Future needs for material by design approaches for processing these nano-composite systems are also discussed. PMID:28809290

Mathematical modeling of high-pH chemical flooding

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhuyan, D.; Lake, L.W.; Pope, G.A.

1990-05-01

This paper describes a generalized compositional reservoir simulator for high-pH chemical flooding processes. This simulator combines the reaction chemistry associated with these processes with the extensive physical- and flow-property modeling schemes of an existing micellar/polymer flood simulator, UTCHEM. Application of the model is illustrated for cases from a simple alkaline preflush to surfactant-enhanced alkaline-polymer flooding.

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.

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.

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.

A highly efficient electrocatalyst for oxygen reduction reaction: phosphorus and nitrogen co-doped hierarchically ordered porous carbon derived from an iron-functionalized polymer

NASA Astrophysics Data System (ADS)

Deng, Chengwei; Zhong, Hexiang; Li, Xianfeng; Yao, Lan; Zhang, Huamin

2016-01-01

Heteroatom-doped carbon materials have shown respectable activity for the oxygen reduction reaction (ORR) in alkaline media. However, the performances of these materials are not satisfactory for energy conversion devices, such as fuel cells. Here, we demonstrate a new type of phosphorus and nitrogen co-doped hierarchically ordered porous carbon (PNHOPC) derived from an iron-functionalized mesoporous polymer through an evaporation-induced self-assembly process that simultaneously combines the carbonization and nitrogen doping processes. The soft template and the nitrogen doping process facilitate the formation of the hierarchically ordered structure for the PNHOPC. The catalyst possesses a large surface area (1118 cm2 g-1) and a pore volume of 1.14 cm3 g-1. Notably, it exhibits excellent ORR catalytic performance, superior stability and methanol tolerance in acidic electrolytes, thus making the catalyst promising for fuel cells. The correlations between the unique pore structure and the nitrogen and phosphorus configuration of the catalysts with high catalytic activity are thoroughly investigated.Heteroatom-doped carbon materials have shown respectable activity for the oxygen reduction reaction (ORR) in alkaline media. However, the performances of these materials are not satisfactory for energy conversion devices, such as fuel cells. Here, we demonstrate a new type of phosphorus and nitrogen co-doped hierarchically ordered porous carbon (PNHOPC) derived from an iron-functionalized mesoporous polymer through an evaporation-induced self-assembly process that simultaneously combines the carbonization and nitrogen doping processes. The soft template and the nitrogen doping process facilitate the formation of the hierarchically ordered structure for the PNHOPC. The catalyst possesses a large surface area (1118 cm2 g-1) and a pore volume of 1.14 cm3 g-1. Notably, it exhibits excellent ORR catalytic performance, superior stability and methanol tolerance in acidic

Selenium-substituted polymers for improved photovoltaic performance.

PubMed

Yu, Jiangsheng; Ding, Guanqun; Hai, Jiefeng; Zhu, Enwei; Yin, Xinxing; Xu, Zhongsheng; Zhou, Baojing; Zhang, Fujun; Ma, Wanli; Tang, Weihua

2016-03-21

Four isostructural donor-acceptor alternating polymers of benzodithiophene (BDT)/naphthodifuran (NDF) and benzoselenadiazole (BSe)/benzothiadiazole (BT) have been developed and evaluated for organic photovoltaics. The substitution of one-atom (Se for S) in the accepting units exerts remarkable impact on the optoelectronic properties of polymers. Extended absorption, narrowed bandgap and higher HOMO energy levels were observed for Se-containing polymers in comparison to their S-containing counterparts. Theoretical calculations confirmed the measurable effect on energy levels as found in experimental studies. Bulk-heterojuction solar cells based on the BDT-BSe copolymer and [6,6]-phenyl-C71-butyric acid methyl ester (1 : 2, w/w) blend films deliver the best PCE of 5.40%. BSe-based polymers showed enhanced photovoltaic performances than BT-based polymers. The device performance is found to be strongly dependent on the processing conditions and morphology of the active layers.

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.

Performance of polymer nano composite membrane electrode assembly using Alginate as a dopant in polymer electrolyte membrane fuel cell

NASA Astrophysics Data System (ADS)

Mulijani, S.

2017-01-01

Polymer membrane and composite polymer for membrane electrode assembly (MEAs) are synthesized and studied for usage in direct methanol fuel cell (DMFC). In this study, we prepared 3 type of MEAs, polystyrene (PS), sulfonated polystyrene (SPS) and composite polymer SPS-alginat membrane via catalyst hot pressed method. The performance and properties of prepared MEAs were evaluated and analyzed by impedance spectrometry and scanning electron microscopy (SEM). The result showed that, water up take of MEA composite polymer SPS-alginate was obtained higher than that in SPS and PS. The proton conductivity of MEA-SPS-alginate was also higher than that PS and PSS. SEM characterization revealed that the intimate contact between the carbon catalyst layers (CL) and the membranes, and the uniformly porous structure correlate positively with the MEAs prepared by hot pressed method, exhibiting high performances for DMFC.

Preparation and performance evaluation of novel alkaline stable anion exchange membranes

NASA Astrophysics Data System (ADS)

Irfan, Muhammad; Bakangura, Erigene; Afsar, Noor Ul; Hossain, Md. Masem; Ran, Jin; Xu, Tongwen

2017-07-01

Novel alkaline stable anion exchange membranes are prepared from various amounts of N-methyl dipicolylamine (MDPA) and brominated poly (2,6-dimethyl-1,4-phenylene oxide) (BPPO). The dipicolylamine and MDPA are synthesized through condensation reaction and confirmed by 1H NMR spectroscopy. The morphologies of prepared membranes are investigated by atomic force microscopy (AFM), fourier transform infrared spectroscopy (FTIR), 1H NMR spectroscopy and scanning electron microscopy (SEM). The electrochemical and physical properties of AEMs are tested comprising water uptake (WU), ion exchange capacity (IEC), alkaline stability, linear expansion ratio (LER), thermal stability and mechanical stability. The obtained hydroxide conductivity of MDPA-4 is 66.5 mS/cm at 80 °C. The MDPA-4 membrane shows good alkaline stability, high hydroxide conductivity, low methanol permeability (3.43 × 10-7 cm2/s), higher selectivity (8.26 × 107 mS s/cm3), less water uptake (41.1%) and lower linear expansion (11.1%) despite of high IEC value (1.62 mmol/g). The results prove that MDPA membranes have great potential application in anion exchange membrane fuel cell.

Multifunctional semi-interpenetrating polymer network-nanoencapsulated cathode materials for high-performance lithium-ion batteries.

PubMed

Kim, Ju-Myung; Park, Jang-Hoon; Lee, Chang Kee; Lee, Sang-Young

2014-04-08

As a promising power source to boost up advent of next-generation ubiquitous era, high-energy density lithium-ion batteries with reliable electrochemical properties are urgently requested. Development of the advanced lithium ion-batteries, however, is staggering with thorny problems of performance deterioration and safety failures. This formidable challenge is highly concerned with electrochemical/thermal instability at electrode material-liquid electrolyte interface, in addition to structural/chemical deficiency of major cell components. Herein, as a new concept of surface engineering to address the abovementioned interfacial issue, multifunctional conformal nanoencapsulating layer based on semi-interpenetrating polymer network (semi-IPN) is presented. This unusual semi-IPN nanoencapsulating layer is composed of thermally-cured polyimide (PI) and polyvinyl pyrrolidone (PVP) bearing Lewis basic site. Owing to the combined effects of morphological uniqueness and chemical functionality (scavenging hydrofluoric acid that poses as a critical threat to trigger unwanted side reactions), the PI/PVP semi-IPN nanoencapsulated-cathode materials enable significant improvement in electrochemical performance and thermal stability of lithium-ion batteries.

Multifunctional semi-interpenetrating polymer network-nanoencapsulated cathode materials for high-performance lithium-ion batteries

NASA Astrophysics Data System (ADS)

Kim, Ju-Myung; Park, Jang-Hoon; Lee, Chang Kee; Lee, Sang-Young

2014-04-01

As a promising power source to boost up advent of next-generation ubiquitous era, high-energy density lithium-ion batteries with reliable electrochemical properties are urgently requested. Development of the advanced lithium ion-batteries, however, is staggering with thorny problems of performance deterioration and safety failures. This formidable challenge is highly concerned with electrochemical/thermal instability at electrode material-liquid electrolyte interface, in addition to structural/chemical deficiency of major cell components. Herein, as a new concept of surface engineering to address the abovementioned interfacial issue, multifunctional conformal nanoencapsulating layer based on semi-interpenetrating polymer network (semi-IPN) is presented. This unusual semi-IPN nanoencapsulating layer is composed of thermally-cured polyimide (PI) and polyvinyl pyrrolidone (PVP) bearing Lewis basic site. Owing to the combined effects of morphological uniqueness and chemical functionality (scavenging hydrofluoric acid that poses as a critical threat to trigger unwanted side reactions), the PI/PVP semi-IPN nanoencapsulated-cathode materials enable significant improvement in electrochemical performance and thermal stability of lithium-ion batteries.

Ratiometric detection of copper ions and alkaline phosphatase activity based on semiconducting polymer dots assembled with rhodamine B hydrazide.

PubMed

Sun, Junyong; Mei, Han; Gao, Feng

2017-05-15

The rational surface functionalization of semiconducting polymer dots (Pdots) has attracted much attention to extend their applications in fabricating chemo/biosensing platform. In this study, a novel ratiometric fluorescent sensing platform using functionalized Pdots as probes for fluorescence signal transmission has been designed for sensing Cu(Ⅱ) and activity of alkaline phosphatase (ALP) with high selectivity and enhanced sensitivity. The highly fluorescent Pdots were firstly prepared with Poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(1,4-benzo-{2,1',3}-thiadiazole)] (PFBT) via nanoprecipitation method, and then assembled with non-fluorescent rhodamine B hydrazide (RB-hy), which shows special binding activity to Cu(Ⅱ), through adsorption process to obtain functionalized nanohybrids, Pdots@RB-hy. As thus, a FRET donors/acceptors pair, in which PFBT Pdots act as energy donors while RB-hy-Cu(II) complexes act as energy acceptors were constructed. On the basis of the varies in fluorescence intensities of donors/acceptors in the presence of different amounts of Cu(II), a ratiometric method for sensing Cu(II) has been proposed. The proposed ratiometric Cu(II) sensor shows a good linear detection range from 0.05 to 5μM with a detection limit of 15nM. Furthermore, using the Pdots@RB-hy-Cu(II) system as signal transducer, a ratiometric sensing for alkaline phosphatase (ALP) activity has also been established with pyrophosphate (PPi) as substrates. The constructed ratiometric sensor of ALP activity displays a linear detection range from 0.005 to 15UL -1 with a detection limit of 0.0018UL -1 . The sensor was further successfully used for ALP activity detection in human serum with satisfactory results. Copyright © 2016 Elsevier B.V. All rights reserved.

3D Structural Model of High-Performance Non-Fullerene Polymer Solar Cells as Revealed by High-Resolution AFM.

PubMed

Shi, Shaowei; Chen, Xiaofeng; Liu, Xubo; Wu, Xuefei; Liu, Feng; Zhang, Zhi-Guo; Li, Yongfang; Russell, Thomas P; Wang, Dong

2017-07-26

Rapid improvements in nonfullerene polymer solar cells (PSCs) have brought power conversion efficiencies to greater than 12%. To further improve device performance, a fundamental understanding of the correlations between structure and performance is essential. In this paper, based on a typical high-performance system consisting of J61(one donor-acceptor (D-A) copolymer of benzodithiophene and fluorine substituted benzotriazole) and ITIC (3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone)-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2',3'-d']-s-indaceno[1,2-b:5,6-b']-dithiophene), a 3D structural model is directly imaged by employing high-resolution atomic force microscopy (AFM). Hierarchical morphologies ranging from fiberlike crystallites, several nanometers in size, to a bicontinuous morphology, having domains tens of nanometers in size, are observed. A fibrillar interpenetrating networks of J61-rich domains embedded in a matrix comprised of a J61/ITIC is seen, reflecting the partial miscibility of J61 with ITIC. These hierarchical nanostructural characteristics are coupled to significantly enhanced exciton dissociation, and further contribute to photocurrent and final device performance.

Alkali Salt-Doped Highly Transparent and Thickness-Insensitive Electron-Transport Layer for High-Performance Polymer Solar Cell.

PubMed

Xu, Rongguo; Zhang, Kai; Liu, Xi; Jin, Yaocheng; Jiang, Xiao-Fang; Xu, Qing-Hua; Huang, Fei; Cao, Yong

2018-01-17

Solution-processable highly transparent and thickness-insensitive hybrid electron-transport layer (ETL) with enhanced electron-extraction and electron-transport properties for high-performance polymer solar cell was reported. With the incorporation of Cs 2 CO 3 into the poly[(9,9-bis(6'-((N,N-diethyl)-N-ethylammonium)-hexyl)-2,7-fluorene)-alt-1,4-diphenylsulfide]dibromide (PF6NPSBr) ETL, the power conversion efficiency (PCE) of resulted polymer solar cells (PSCs) was significantly enhanced due to the favorable interfacial contact, energy-level alignment, and thus facile electron transport in the PSC device. These organic-inorganic hybrid ETLs also exhibited high transparency and high electron mobility. All of these combined properties ensured us to design novel thickness-insensitive ETLs that avoid the parasitic absorption of ETL itself simultaneously. With the conventional device structure with poly{4,8-bis[5-(2-ethylhexyl)thiophen-2-yl]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl-alt-3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophene-4,6-diyl} (PTB7-Th) as a donor and [6,6]-phenyl-C71-butyric acid methyl ester (PC 71 BM) as an acceptor, devices with hybrid ETLs exhibited PCE of 8.30-9.45% within a wide range of ETL thickness. A notable PCE of 10.78% was achieved with the thick active layer poly(2,5-thiophene-alt-5,5'-(5,10-bis(4-(2-octyldodecyl)thiophen-2-yl)naphtho[1,2-c:5,6-c']bis([1,2,5]thiadiazole)) (PTNT812):PC 71 BM. These findings indicated that doping alkali salt into the organic interfacial materials can be a promising strategy to design highly efficient and thickness-insensitive ETL, which may be suitable for large-area PSC modules device fabrication with roll-to-roll printing technique.

Self Assembly and Interface Engineering of Organic Functional Materials for High Performance Polymer Solar Cells

NASA Astrophysics Data System (ADS)

Jen, Alex

2010-03-01

The performance of polymer solar cells are strongly dependent on the efficiency of light harvesting, exciton dissociation, charge transport, and charge collection at the metal/organic, metal/metal oxide, and organic/metal oxide interfaces. To improve the device performance, two parallel approaches were used: 1) developing novel low band gap conjugated polymers with good charge-transporting properties and 2) modifying the interfaces between the organic/metal oxide and organic/metal layers with functional self-assembling monolayers to tune their energy barriers. Moreover, the molecule engineering approach was also used to tune the energy level, charge mobility, and morphology of organic semiconductors.

Solution-Processed Donor-Acceptor Polymer Nanowire Network Semiconductors For High-Performance Field-Effect Transistors

PubMed Central

Lei, Yanlian; Deng, Ping; Li, Jun; Lin, Ming; Zhu, Furong; Ng, Tsz-Wai; Lee, Chun-Sing; Ong, Beng S.

2016-01-01

Organic field-effect transistors (OFETs) represent a low-cost transistor technology for creating next-generation large-area, flexible and ultra-low-cost electronics. Conjugated electron donor-acceptor (D-A) polymers have surfaced as ideal channel semiconductor candidates for OFETs. However, high-molecular weight (MW) D-A polymer semiconductors, which offer high field-effect mobility, generally suffer from processing complications due to limited solubility. Conversely, the readily soluble, low-MW D-A polymers give low mobility. We report herein a facile solution process which transformed a lower-MW, low-mobility diketopyrrolopyrrole-dithienylthieno[3,2-b]thiophene (I) into a high crystalline order and high-mobility semiconductor for OFETs applications. The process involved solution fabrication of a channel semiconductor film from a lower-MW (I) and polystyrene blends. With the help of cooperative shifting motion of polystyrene chain segments, (I) readily self-assembled and crystallized out in the polystyrene matrix as an interpenetrating, nanowire semiconductor network, providing significantly enhanced mobility (over 8 cm2V−1s−1), on/off ratio (107), and other desirable field-effect properties that meet impactful OFET application requirements. PMID:27091315

Composite-Based High Performance Electroactive Polymers For Remotely Controlled Mechanical Manipulations in NASA Applications

NASA Technical Reports Server (NTRS)

Zhang, Q. M.

2003-01-01

This program supported investigation of an all-polymer percolative composite which exhibits very high dielectric constant (less than 7,000). The experimental results show that the dielectric behavior of this new class of percolative composites follows the prediction of the percolation theory and the analysis of the conductive percolation phenomena. The very high dielectric constant of the all-polymer composites which are also very flexible and possess elastic modulus not very much different from that of the insulation polymer matrix makes it possible to induce a high electromechanical response under a much reduced electric field (a strain of 2.65% with an elastic energy density of 0.18 J/cu cm can be achieved under a field of 16 MV/m). Data analysis also suggests that in these composites, the non-uniform local field distribution as well as interface effects can significantly enhance the strain responses. Furthermore, the experimental data as well as the data analysis indicate that the conduction loss in these composites will not affect the strain hysteresis.

Molecularly imprinted polymer for selective extraction of malachite green from seawater and seafood coupled with high-performance liquid chromatographic determination.

PubMed

Lian, Ziru; Wang, Jiangtao

2012-12-01

In this paper, a highly selective sample cleanup procedure combining molecular imprinting technique (MIT) and solid-phase extraction (SPE) was developed for the isolation of malachite green in seawater and seafood samples. The molecularly imprinted polymer (MIP) was prepared using malachite green as the template molecule, methacrylic acid as the functional monomer and ethylene glycol dimethacrylate as the cross-linking monomer. The imprinted polymer and non-imprinted polymer were characterized by scanning electron microscope and static adsorption experiments. The MIP showed a high adsorption capacity and was used as selective sorbent for the SPE of malachite green. An off-line molecularly imprinted solid-phase extraction (MISPE) method followed by high-performance liquid chromatography with diodearray detection for the analysis of malachite green in seawater and seafood samples was also established. Finally, five samples were determined. The results showed that malachite green concentration in one seawater sample was at 1.30 μg L⁻¹ and the RSD (n=3) was 4.15%. Crown Copyright © 2012. Published by Elsevier Ltd. All rights reserved.

Flexible high-temperature dielectric materials from polymer nanocomposites.

PubMed

Li, Qi; Chen, Lei; Gadinski, Matthew R; Zhang, Shihai; Zhang, Guangzu; Li, Haoyu; Iagodkine, Elissei; 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.

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.

Compositional and sensory characterization of red wine polymers.

PubMed

Wollmann, Nadine; Hofmann, Thomas

2013-03-06

After isolation from red wine by means of ultrafiltration and gel adsorption chromatography, the composition of the highly astringent tasting high-molecular weight polymers was analyzed by means of HPLC-MS/MS, HPLC-UV/vis, and ion chromatography after thiolytic, alkaline, and acidic depolymerization and, on the basis of the quantitative data obtained as well as model incubation experiments, key structural features of the red wine polymers were proposed. The structural backbone of the polymers seems to be comprised of a procyanidin chain with (-)-epicatechin, (+)-catechin, (-)-epicatechin-3-O-gallate units as extension and terminal units as well as (-)-epigallocatechin as extension units. In addition, acetaldehyde was shown to link different procyanidins at the A-ring via an 1,1-ethylene bridge and anthocyanins and pyranoanthocyanins were found to be linked to the procyanidin backbone via a C-C-linkage at position C(6) or C(8), respectively. Alkaline hydrolysis demonstrated the polymeric procyanidins to be esterified with various organic acids and phenolic acids, respectively. In addition, the major part of the polysaccharides present in the red wine polymeric fraction were found not to be covalently linked to procyanidins. Interestingly, sensory evaluation of individual fractions of the red wine polymers did not show any significant difference in the astringent threshold concentrations, nor in the astringency intensity in supra-threshold concentrations and demonstrated the mean degree of polymerization as well as the galloylation degree not to have an significant influence on the astringency perception.

Inorganic polymers from laterite using activation with phosphoric acid and alkaline sodium silicate solution: Mechanical and microstructural properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lassinantti Gualtieri, Magdalena, E-mail: magdalena.gualtieri@unimore.it; Romagnoli, Marcello; Pollastri, Simone

2015-01-15

Geopolymers from laterite, an iron-rich soil available in developing countries, have great potential as building materials. In this work, laterite from Togo (Africa) was used to prepare geopolymers using both phosphoric acid and alkaline sodium silicate solution. Microstructural properties were investigated by scanning electron microscopy, X-ray powder diffraction and mercury porosimetry, whereas thermal properties were evaluated by thermal analyses. The local environment of iron was studied by X-ray Absorption Spectroscopy (XANES region). The mechanical properties were determined. Modulus of Rupture and Young's modulus fell in the ranges 3.3–4.5 MPa and 12–33 GPa, respectively, rendering the materials good candidates for constructionmore » purposes. Heating above 900 °C results in weight-gain, presumably due to iron redox reactions. X-ray Absorption Spectroscopy data evidence changes in the chemical and structural environments of iron following thermal treatment of geopolymers. These changes indicate interaction between the geopolymer structure and iron during heating, possibly leading to redox properties. -- Highlights: •Geopolymerization of laterite is promising for fabrication of building materials. •Both phosphoric acid and alkaline sodium silicate solution can be used for activation. •Thermally activated redox properties of the inorganic polymers were observed.« less

Tough high performance composite matrix

NASA Technical Reports Server (NTRS)

Pater, Ruth H. (Inventor); Johnston, Norman J. (Inventor)

1994-01-01

This invention is a semi-interpentrating 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. Provided is an improved high temperature matrix resin which is capable of performing in the 200 to 300 C range. This resin has significantly improved toughness and microcracking resistance, excellent processability, mechanical performance, and moisture and solvent resistances.

High power, gel polymer lithium-ion cells with improved low temperature performance for NASA and DoD applications

NASA Technical Reports Server (NTRS)

Smart, M. C.; Ratnakumar, B. V.; Whitcanack, L. D.; Chin, K. B.; Surampudi, S.; Narayanan, S. R.; Alamgir, Mohamed; Yu, Ji-Sang; Plichta, Edward P.

2004-01-01

Both NASA and the U.S. Army have interest in developing secondary energy storage devices that are capable of meeting the demanding performance requirements of aerospace and man-portable applications. In order to meet these demanding requirements, gel-polymer electrolyte-based lithium-ion cells are being actively considered, due to their promise of providing high specific energy and enhanced safety aspects.

Interface-designed Membranes with Shape-controlled Patterns for High-performance Polymer Electrolyte Membrane Fuel Cells

PubMed Central

Jeon, Yukwon; Kim, Dong Jun; Koh, Jong Kwan; Ji, Yunseong; Kim, Jong Hak; Shul, Yong-Gun

2015-01-01

Polymer electrolyte membrane fuel cell is a promising zero-emission power generator for stationary/automotive applications. However, key issues, such as performance and costs, are still remained for an economical commercialization. Here, we fabricated a high-performance membrane electrode assembly (MEA) using an interfacial design based on well-arrayed micro-patterned membranes including circles, squares and hexagons with different sizes, which are produced by a facile elastomeric mold method. The best MEA performance is achieved using patterned Nafion membrane with a circle 2 μm in size, which exhibited a very high power density of 1906 mW/cm2 at 75 °C and Pt loading of 0.4 mg/cm2 with 73% improvement compared to the commercial membrane. The improved performance are attributed to the decreased MEA resistances and increased surface area for higher Pt utilization of over 80%. From these enhanced properties, it is possible to operate at lower Pt loading of 0.2 mg/cm2 with an outstanding performance of 1555 mW/cm2 and even at air/low humidity operations. PMID:26552839

Interface-designed Membranes with Shape-controlled Patterns for High-performance Polymer Electrolyte Membrane Fuel Cells

NASA Astrophysics Data System (ADS)

Jeon, Yukwon; Kim, Dong Jun; Koh, Jong Kwan; Ji, Yunseong; Kim, Jong Hak; Shul, Yong-Gun

2015-11-01

Polymer electrolyte membrane fuel cell is a promising zero-emission power generator for stationary/automotive applications. However, key issues, such as performance and costs, are still remained for an economical commercialization. Here, we fabricated a high-performance membrane electrode assembly (MEA) using an interfacial design based on well-arrayed micro-patterned membranes including circles, squares and hexagons with different sizes, which are produced by a facile elastomeric mold method. The best MEA performance is achieved using patterned Nafion membrane with a circle 2 μm in size, which exhibited a very high power density of 1906 mW/cm2 at 75 °C and Pt loading of 0.4 mg/cm2 with 73% improvement compared to the commercial membrane. The improved performance are attributed to the decreased MEA resistances and increased surface area for higher Pt utilization of over 80%. From these enhanced properties, it is possible to operate at lower Pt loading of 0.2 mg/cm2 with an outstanding performance of 1555 mW/cm2 and even at air/low humidity operations.

High performance photolithographically-patterned polymer thin-film transistors gated with an ionic liquid/poly(ionic liquid) blend ion gel

NASA Astrophysics Data System (ADS)

Thiburce, Q.; Porcarelli, L.; Mecerreyes, D.; Campbell, A. J.

2017-06-01

We demonstrate the fabrication of polymer thin-film transistors gated with an ion gel electrolyte made of the blend of an ionic liquid and a polymerised ionic liquid. The ion gel exhibits a high stability and ionic conductivity, combined with facile processing by simple drop-casting from solution. In order to avoid parasitic effects such as high hysteresis, high off-currents, and slow switching, a fluorinated photoresist is employed in order to enable high-resolution orthogonal patterning of the polymer semiconductor over an area that precisely defines the transistor channel. The resulting devices exhibit excellent characteristics, with an on/off ratio of 106, low hysteresis, and a very large transconductance of 3 mS. We show that this high transconductance value is mostly the result of ions penetrating the polymer film and doping the entire volume of the semiconductor, yielding an effective capacitance per unit area of about 200 μF cm-2, one order of magnitude higher than the double layer capacitance of the ion gel. This results in channel currents larger than 1 mA at an applied gate bias of only -1 V. We also investigate the dynamic performance of the devices and obtain a switching time of 20 ms, which is mostly limited by the overlap capacitance between the ion gel and the source and drain contacts.

Optimizing the performance of bandpass photon detectors for inverse photoemission: Transmission of alkaline earth fluoride window crystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thiede, Christian, E-mail: christian.thiede@uni-muenster.de; Schmidt, Anke B.; Donath, Markus

2015-08-15

Bandpass photon detectors are widely used in inverse photoemission in the isochromat mode at energies in the vacuum-ultraviolet spectral range. The energy bandpass of gas-filled counters is usually formed by the ionization threshold of the counting gas as high-pass filter and the transmission cutoff of an alkaline earth fluoride window as low-pass filter. The transmission characteristics of the window have, therefore, a crucial impact on the detector performance. We present transmission measurements in the vacuum-ultraviolet spectral range for alkaline earth fluoride window crystals in the vicinity of the transmission cutoff as a function of crystal purity, surface finish, surface contamination,more » temperature, and thickness. Our findings reveal that the transmission characteristics of the window crystal and, thus, the detector performance depend critically on these window parameters.« less

Effect of Proteolysis with Alkaline Protease Following High Hydrostatic Pressure Treatment on IgE Binding of Buckwheat Protein.

PubMed

Lee, Chaeyoon; Lee, Wonhui; Han, Youngshin; Oh, Sangsuk

2017-03-01

Buckwheat is a popular food material in many Asian countries and it contains major allergenic proteins. This study was performed to analyze the effects of hydrolysis with alkaline protease following high hydrostatic pressure (HHP) treatment on the IgE binding of buckwheat protein. Extracted buckwheat protein was treated with HHP at 600 MPa for 30 min and hydrolyzed with alkaline protease for 240 min. IgE binding was examined using an enzyme-linked immunosorbent assay (ELISA) with serum samples from 14 patients who were allergic to buckwheat. Depending on the serum samples, HHP treatment of buckwheat protein without enzymatic hydrolysis decreased the IgE binding by 8.9% to 73.2% or increased by 31% to 78%. The IgE binding of buckwheat protein hydrolyzed with alkaline protease decreased by 73.8% to 100%. The IgE binding of buckwheat protein hydrolyzed with alkaline protease following HHP treatment decreased by 83.8% to 100%. This suggested that hydrolysis with alkaline protease following HHP treatment could be applied to reduce the IgE binding of buckwheat protein. © 2017 Institute of Food Technologists®.

Metallated porphyrin based porous organic polymers as efficient electrocatalysts

NASA Astrophysics Data System (ADS)

Lu, Guolong; Zhu, Youlong; Xu, Kongliang; Jin, Yinghua; Ren, Zhiyong Jason; Liu, Zhenning; Zhang, Wei

2015-10-01

Developing efficient, stable and low-cost catalysts for Oxygen Reduction Reaction (ORR) is of great significance to many emerging technologies including fuel cells and metal-air batteries. Herein, we report the development of a cobalt(ii) porphyrin based porous organic polymer (CoPOP) and its pyrolyzed derivatives as highly active ORR catalysts. The as-synthesized CoPOP exhibits high porosity and excellent catalytic performance stability, retaining ~100% constant ORR current over 50 000 s in both alkaline and acidic media. Pyrolysis of CoPOP at various temperatures (600 °C, 800 °C, and 1000 °C) yields the materials consisting of graphitic carbon layers and cobalt nanoparticles, which show greatly enhanced catalytic activity compared to the as-synthesized CoPOP. Among them, CoPOP-800/C pyrolyzed at 800 °C shows the highest specific surface area and ORR activity, displaying the most positive half-wave potential (0.825 V vs. RHE) and the largest limited diffusion current density (5.35 mA cm-2) in an alkaline medium, which are comparable to those of commercial Pt/C (20 wt%) (half-wave potential 0.829 V vs. RHE, limited diffusion current density 5.10 mA cm-2). RDE and RRDE experiments indicate that CoPOP-800/C directly reduces molecular oxygen to water through a 4-e- pathway in both alkaline and acidic media. More importantly, CoPOP-800/C exhibits excellent durability and methanol-tolerance under acidic and alkaline conditions, which surpass the Pt/C (20 wt%) system.Developing efficient, stable and low-cost catalysts for Oxygen Reduction Reaction (ORR) is of great significance to many emerging technologies including fuel cells and metal-air batteries. Herein, we report the development of a cobalt(ii) porphyrin based porous organic polymer (CoPOP) and its pyrolyzed derivatives as highly active ORR catalysts. The as-synthesized CoPOP exhibits high porosity and excellent catalytic performance stability, retaining ~100% constant ORR current over 50 000 s in both

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.

Molecularly imprinted polymer cartridges coupled to high performance liquid chromatography (HPLC-UV) for simple and rapid analysis of fenthion in olive oil.

PubMed

Bakas, Idriss; Ben Oujji, Najwa; Istamboulié, Georges; Piletsky, Sergey; Piletska, Elena; Ait-Addi, Elhabib; Ait-Ichou, Ihya; Noguer, Thierry; Rouillon, Régis

2014-07-01

A combination of molecular modelling and a screening of the library of non-imprinted polymers (NIPs) was used to identify acrylamide as a functional monomer with high affinity towards fenthion, organophosphate insecticide, which is frequently used in the treatment of olives. A good correlation was found between the screening tests and modelling of monomer-template interactions performed using a computational approach. Acrylamide-based molecularly imprinted polymer (MIP) and non-imprinted polymer (NIP) were thermally synthesised in dimethyl formamide (porogen) using ethylene glycol dimethacrylate as a cross-linker and 1,1-azo-bis (isobutyronitrile) as an initiator. The chemical and physical properties of the prepared polymers were characterised. The binding of fenthion by the polymers was studied using solvents with different polarities. The developed MIP showed a high selectivity towards fenthion, compared to other organophosphates (dimethoate, methidathion malalthion), and allowed extraction of fenthion from olive oil samples with a recovery rate of about 96%. The extraction of fenthion using MIPs was much more effective than traditional C18 reverse-phase solid phase extraction and allowed to achieve a low detection limit (LOD) (5 µg L(-1)). Copyright © 2014 Elsevier B.V. All rights reserved.

Fine-tuning blend morphology via alkylthio side chain engineering towards high performance non-fullerene polymer solar cells

NASA Astrophysics Data System (ADS)

Li, Ling; Feng, Liuliu; Yuan, Jun; Peng, Hongjian; Zou, Yingping; Li, Yongfang

2018-03-01

Two medium bandgap polymers (ffQx-TS1, ffQx-TS2) were designed and synthesized to investigate the influence of different alkylthio side chain on the morphology and photovoltaic performance of non-fullerene polymer solar cells (PSCs). Both polymers exhibit similar molecular weights and comparable the highest occupied molecular orbital (HOMO) energy level. However, the polymer with straight alkylthio chain delivers a root-mean-square (RMS) of 0.86 nm, which is slightly lower than that with branched chain (1.40 nm). The lower RMS benefits the ohmic contact between the active lay and interface layer, thus enhanced short circuit current (Jsc) (from 13.54 mA cm-1 to 15.25 mA cm-1) could be obtained. Due to the enhancement of Jsc, better power conversion efficiency (PCE) of 7.69% for ffQx-TS2 could be realized. These results indicated that alkylthio side chain engineering is a promising method to improve photovoltaic performance.

High Performance Electroactive Polymer Actuators Based on Sulfonated Block Copolymers Comprising Ionic Liquids

NASA Astrophysics Data System (ADS)

Kim, Onnuri; Park, Moon Jeong

2015-03-01

Electroactive polymer (EAP) actuators that show reversible deformation under external electric stimulus have attracted great attention toward a range of biomimetic applications such as microsensors and artificial muscles. Key challenges to advance the technologies can be placed on the achievement of fast response time, low driving voltage, and durable operation in air. In present study, we are motivated to solve these issues by employing self-assembled block copolymers containing ionic liquids (ILs) as polymer layers in the actuator based on knowledge of factors affecting electromechanical properties of actuators. By controlling the block architecture and molecular weight of block copolymers, bending strain and durability were controlled in a straightforward manner. It has also been revealed that the type of IL makes impact on the EAP actuator performance by determining ion migration dynamics. Our actuators demonstrated large bending strains (up to 4%) under low voltages of 1-3V, which far exceeds the best performance of other EAP actuators reported in the literature. To underpin the molecular-level understanding of actuation mechanisms underlying the improved performance, we carried out in situ spectroscopy and in situ scattering experiments under actuation.

Polymer-fullerene miscibility: a metric for screening new materials for high-performance organic solar cells.

PubMed

Treat, Neil D; Varotto, Alessandro; Takacs, Christopher J; Batara, Nicolas; Al-Hashimi, Mohammed; Heeney, Martin J; Heeger, Alan J; Wudl, Fred; Hawker, Craig J; Chabinyc, Michael L

2012-09-26

The improvement of the power conversion efficiency (PCE) of polymer bulk heterojunction (BHJ) solar cells has generally been achieved through synthetic design to control frontier molecular orbital energies and molecular ordering of the electron-donating polymer. An alternate approach to control the PCE of a BHJ is to tune the miscibility of the fullerene and a semiconducting polymer by varying the structure of the fullerene. The miscibility of a series of 1,4-fullerene adducts in the semiconducting polymer, poly(3-hexylselenophene), P3HS, was measured by dynamic secondary ion mass spectrometry using a model bilayer structure. The microstructure of the bilayer was investigated using high-angle annular dark-field scanning transmission microscopy and linked to the polymer-fullerene miscibility. Finally, P3HS:fullerene BHJ solar cells were fabricated from each fullerene derivative, enabling the correlation of the active layer microstructure to the charge collection efficiency and resulting PCE of each system. The volume fraction of polymer-rich, fullerene-rich, and polymer-fullerene mixed domains can be tuned using the miscibility leading to improvement in the charge collection efficiency and PCE in P3HS:fullerene BHJ solar cells. These results suggest a rational approach to the design of fullerenes for improved BHJ solar cells.

Multifunctional semi-interpenetrating polymer network-nanoencapsulated cathode materials for high-performance lithium-ion batteries

PubMed Central

Kim, Ju-Myung; Park, Jang-Hoon; Lee, Chang Kee; Lee, Sang-Young

2014-01-01

As a promising power source to boost up advent of next-generation ubiquitous era, high-energy density lithium-ion batteries with reliable electrochemical properties are urgently requested. Development of the advanced lithium ion-batteries, however, is staggering with thorny problems of performance deterioration and safety failures. This formidable challenge is highly concerned with electrochemical/thermal instability at electrode material-liquid electrolyte interface, in addition to structural/chemical deficiency of major cell components. Herein, as a new concept of surface engineering to address the abovementioned interfacial issue, multifunctional conformal nanoencapsulating layer based on semi-interpenetrating polymer network (semi-IPN) is presented. This unusual semi-IPN nanoencapsulating layer is composed of thermally-cured polyimide (PI) and polyvinyl pyrrolidone (PVP) bearing Lewis basic site. Owing to the combined effects of morphological uniqueness and chemical functionality (scavenging hydrofluoric acid that poses as a critical threat to trigger unwanted side reactions), the PI/PVP semi-IPN nanoencapsulated-cathode materials enable significant improvement in electrochemical performance and thermal stability of lithium-ion batteries. PMID:24710575

Ultrafine and highly disordered Ni 2 Fe 1 nanofoams enabled highly efficient oxygen evolution reaction in alkaline electrolyte

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fu, Shaofang; Song, Junhua; Zhu, Chengzhou

Nickel iron hydroxides are the most promising non-noble electrocatalysts for oxygen evolution reaction (OER) in alkaline media. By in situ reduction of metal precursors, compositionally controlled three-dimensional (3D) NixFeyB nanofoams (NFs) are synthesized with high surface area and uniformly distributed bimetallic networks. The resultant ultrafine amorphous Ni2Fe1B NFs exhibit extraordinary electrocatalytic performance toward OER and overall water splitting in alkaline media. At a potential as low as 1.42 V (vs. RHE), Ni2Fe1B NFs can deliver a current density of 10 mA/cm2 and show negligible activity loss after 12 hours’ stability test. Even at large current flux of 100 mA/cm2, anmore » ultralow overpotential of 0.27 V is achieved, which is about 0.18 V more negative than benchmark RuO2. Both ex-situ Mӧssbauer spectroscopy and X-ray Absorption Spectroscopy (XAS) reveal a phase separation and transformation for the Ni2Fe1B catalyst during OER process. The evolution of oxidation state and disordered structure of Ni2Fe1B might be a key to the high catalytic performance for OER.« less

Highly ductile UV-shielding polymer composites with boron nitride nanospheres as fillers.

PubMed

Fu, Yuqiao; Huang, Yan; Meng, Wenjun; Wang, Zifeng; Bando, Yoshio; Golberg, Dmitri; Tang, Chengchun; Zhi, Chunyi

2015-03-20

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.

Acidic and alkaline pretreatments of activated carbon and their effects on the performance of air-cathodes in microbial fuel cells.

PubMed

Wang, Xin; Gao, Ningshengjie; Zhou, Qixing; Dong, Heng; Yu, Hongbing; Feng, Yujie

2013-09-01

Activated carbon (AC) is a high performing and cost effective catalyst for oxygen reduction reactions (ORRs) of air-cathodes in microbial fuel cells (MFCs). Acidic (HNO3) and alkaline (KOH) pretreatments on AC at low temperature (85°C) are conducted to enhance the performance of MFCs. The alkaline pretreatment increased the power density by 16% from 804±70 to 957±31 mW m(-2), possibly due to the decrease of ohmic resistance (from 20.58 to 19.20 Ω) and the increase of ORR activities provided by the adsorbed hydroxide ion and extra micropore area/volume after alkaline pretreatment. However, acidic pretreatment decreased the power output to 537±36 mW m(-2), which can be mainly attributed to the corrosion by adsorbed proton at the interface of AC powder and stainless steel mesh and the decreased pore area. Copyright © 2013 Elsevier Ltd. All rights reserved.

Performance Enhancement of Polymer Solar Cells by Using Two Polymer Donors with Complementary Absorption Spectra.

PubMed

Lu, Heng; Zhang, Xuejuan; Li, Cuihong; Wei, Hedi; Liu, Qian; Li, Weiwei; Bo, Zhishan

2015-07-01

Performance enhancement of polymer solar cells (PSCs) is achieved by expanding the absorption of the active layer of devices. To better match the spectrum of solar radiation, two polymers with different band gaps are used as the donor material to fabricate ternary polymer cells. Ternary blend PSCs exhibit an enhanced short-circuit current density and open-circuit voltage in comparison with the corresponding HD-PDFC-DTBT (HD)- and DT-PDPPTPT (DPP)-based binary polymer solar cells, respectively. Ternary PSCs show a power conversion efficiency (PCE) of 6.71%, surpassing the corresponding binary PSCs. This work demonstrates that the fabrication of ternary PSCs by using two polymers with complementary absorption is an effective way to improve the device performance. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Shifts in leaf N:P stoichiometry during rehabilitation in highly alkaline bauxite processing residue sand

PubMed Central

Goloran, Johnvie B.; Chen, Chengrong; Phillips, Ian R.; Elser, James J.

2015-01-01

Large quantities of sodic and alkaline bauxite residue are produced globally as a by-product from alumina refineries. Ecological stoichiometry of key elements [nitrogen (N) and phosphorus (P)] plays a critical role in establishing vegetation cover in bauxite residue sand (BRS). Here we examined how changes in soil chemical properties over time in rehabilitated sodic and alkaline BRS affected leaf N to P stoichiometry of native species used for rehabilitation. Both Ca and soil pH influenced the shifts in leaf N:P ratios of the study species as supported by consistently significant positive relationships (P < 0.001) between these soil indices and leaf N:P ratios. Shifts from N to P limitation were evident for N-fixing species, while N limitation was consistently experienced by non-N-fixing plant species. In older rehabilitated BRS embankments, soil and plant indices (Ca, Na, pH, EC, ESP and leaf N:P ratios) tended to align with those of the natural ecosystem, suggesting improved rehabilitation performance. These findings highlight that leaf N:P stoichiometry can effectively provide a meaningful assessment on understanding nutrient limitation and productivity of native species used for vegetating highly sodic and alkaline BRS, and is a crucial indicator for assessing ecological rehabilitation performance. PMID:26443331

Shifts in leaf N:P stoichiometry during rehabilitation in highly alkaline bauxite processing residue sand.

PubMed

Goloran, Johnvie B; Chen, Chengrong; Phillips, Ian R; Elser, James J

2015-10-07

Large quantities of sodic and alkaline bauxite residue are produced globally as a by-product from alumina refineries. Ecological stoichiometry of key elements [nitrogen (N) and phosphorus (P)] plays a critical role in establishing vegetation cover in bauxite residue sand (BRS). Here we examined how changes in soil chemical properties over time in rehabilitated sodic and alkaline BRS affected leaf N to P stoichiometry of native species used for rehabilitation. Both Ca and soil pH influenced the shifts in leaf N:P ratios of the study species as supported by consistently significant positive relationships (P < 0.001) between these soil indices and leaf N:P ratios. Shifts from N to P limitation were evident for N-fixing species, while N limitation was consistently experienced by non-N-fixing plant species. In older rehabilitated BRS embankments, soil and plant indices (Ca, Na, pH, EC, ESP and leaf N:P ratios) tended to align with those of the natural ecosystem, suggesting improved rehabilitation performance. These findings highlight that leaf N:P stoichiometry can effectively provide a meaningful assessment on understanding nutrient limitation and productivity of native species used for vegetating highly sodic and alkaline BRS, and is a crucial indicator for assessing ecological rehabilitation performance.

Ion exchange polymers and method for making

NASA Technical Reports Server (NTRS)

Philipp, Warren H. (Inventor); Street, Kenneth W., Jr. (Inventor)

1994-01-01

An ion exchange polymer comprised of an alkali metal or alkaline earth metal salt of a poly(carboxylic acid) in a poly(vinyl acetal) matrix is described. The polymer is made by treating a mixture made of poly(vinyl alcohol) and poly(acrylic acid) with a suitable aldehyde and an acid catalyst to cause acetalization with some cross-linking. The material is then subjected to an alkaline aqueous solution of an alkali metal salt or an alkali earth metal salt. All of the film forming and cross-linking steps can be carried out simultaneously, if desired.

Recent advances in polymer solar cells: realization of high device performance by incorporating water/alcohol-soluble conjugated polymers as electrode buffer layer.

PubMed

He, Zhicai; Wu, Hongbin; Cao, Yong

2014-02-01

This Progress Report highlights recent advances in polymer solar cells with special attention focused on the recent rapid-growing progress in methods that use a thin layer of alcohol/water-soluble conjugated polymers as key component to obtain optimized device performance, but also discusses novel materials and device architectures made by major prestigious institutions in this field. We anticipate that due to drastic improvements in efficiency and easy utilization, this method opens up new opportunities for PSCs from various material systems to improve towards 10% efficiency, and many novel device structures will emerge as suitable architectures for developing the ideal roll-to-roll type processing of polymer-based solar cells. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

High performance p-type organic thin film transistors with an intrinsically photopatternable, ultrathin polymer dielectric layer☆

PubMed Central

Petritz, Andreas; Wolfberger, Archim; Fian, Alexander; Krenn, Joachim R.; Griesser, Thomas; Stadlober, Barbara

2013-01-01

A high-performing bottom-gate top-contact pentacene-based oTFT technology with an ultrathin (25–48 nm) and electrically dense photopatternable polymeric gate dielectric layer is reported. The photosensitive polymer poly((±)endo,exo-bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid, diphenylester) (PNDPE) is patterned directly by UV-exposure (λ = 254 nm) at a dose typical for conventionally used negative photoresists without the need for any additional photoinitiator. The polymer itself undergoes a photo-Fries rearrangement reaction under UV illumination, which is accompanied by a selective cross-linking of the macromolecules, leading to a change in solubility in organic solvents. This crosslinking reaction and the negative photoresist behavior are investigated by means of sol–gel analysis. The resulting transistors show a field-effect mobility up to 0.8 cm2 V−1 s−1 at an operation voltage as low as −4.5 V. The ultra-low subthreshold swing in the order of 0.1 V dec−1 as well as the completely hysteresis-free transistor characteristics are indicating a very low interface trap density. It can be shown that the device performance is completely stable upon UV-irradiation and development according to a very robust chemical rearrangement. The excellent interface properties, the high stability and the small thickness make the PNDPE gate dielectric a promising candidate for fast organic electronic circuits. PMID:24748853

Polymer Brushes under High Load

PubMed Central

Balko, Suzanne M.; Kreer, Torsten; Costanzo, Philip J.; Patten, Tim E.; Johner, Albert; Kuhl, Tonya L.; Marques, Carlos M.

2013-01-01

Polymer coatings are frequently used to provide repulsive forces between surfaces in solution. After 25 years of design and study, a quantitative model to explain and predict repulsion under strong compression is still lacking. Here, we combine experiments, simulations, and theory to study polymer coatings under high loads and demonstrate a validated model for the repulsive forces, proposing that this universal behavior can be predicted from the polymer solution properties. PMID:23516470

High strength films from oriented, hydrogen-bonded "graphamid" 2D polymer molecular ensembles.

PubMed

Sandoz-Rosado, Emil; Beaudet, Todd D; Andzelm, Jan W; Wetzel, Eric D

2018-02-27

The linear polymer poly(p-phenylene terephthalamide), better known by its tradename Kevlar, is an icon of modern materials science due to its remarkable strength, stiffness, and environmental resistance. Here, we propose a new two-dimensional (2D) polymer, "graphamid", that closely resembles Kevlar in chemical structure, but is mechanically advantaged by virtue of its 2D structure. Using atomistic calculations, we show that graphamid comprises covalently-bonded sheets bridged by a high population of strong intermolecular hydrogen bonds. Molecular and micromechanical calculations predict that these strong intermolecular interactions allow stiff, high strength (6-8 GPa), and tough films from ensembles of finite graphamid molecules. In contrast, traditional 2D materials like graphene have weak intermolecular interactions, leading to ensembles of low strength (0.1-0.5 GPa) and brittle fracture behavior. These results suggest that hydrogen-bonded 2D polymers like graphamid would be transformative in enabling scalable, lightweight, high performance polymer films of unprecedented mechanical performance.

A High-Performance Nanocomposite Material Based on Functionalized Carbon Nanotube and Polymer for Gas Sensing Applications

NASA Astrophysics Data System (ADS)

Wang, L. C.; Tang, K. T.; Kuo, C. T.; Yang, S. R.; Sung, Yuh; Hsu, H. L.; Jehng, J. M.

2009-05-01

The aim of this study is to develop a novel chemical gas sensing nanocomposite material. The traditional use for carbon nanotube in gas sensing polymer is to increase the composite's conductivity. However, we added functionalized carbon nanotube to fill the free volume of the sensing polymer films and enhance the gas absorption/desorption response time of these nanocomposites. These sensing materials were prepared by mixing functionalized multiwalled carbon nanotubes (MWNTs) and Poly (n, n dimethylamino propylsilsequioxane) SXNR polymer. These new materials were coated on the Surface Acoustic Wave (SAW) device, which is expected to increase its sensitivity in analyzing specific classes of vapors. The proposed materials showed an enhanced sensitivity upon exposure to ethanol and dimethyl methylphosphonate (Dmmp) vapors. Additionally, the performances of our nanocomposite film are much higher than those polymers without functionalized carbon nanotubes.

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.

Two-Dimensional Polymer Synthesized via Solid-State Polymerization for High-Performance Supercapacitors.

PubMed

Liu, Wei; Ulaganathan, Mani; Abdelwahab, Ibrahim; Luo, Xin; Chen, Zhongxin; Rong Tan, Sherman Jun; Wang, Xiaowei; Liu, Yanpeng; Geng, Dechao; Bao, Yang; Chen, Jianyi; Loh, Kian Ping

2018-01-23

Two-dimensional (2-D) polymer has properties that are attractive for energy storage applications because of its combination of heteroatoms, porosities and layered structure, which provides redox chemistry and ion diffusion routes through the 2-D planes and 1-D channels. Here, conjugated aromatic polymers (CAPs) were synthesized in quantitative yield via solid-state polymerization of phenazine-based precursor crystals. By choosing flat molecules (2-TBTBP and 3-TBQP) with different positions of bromine substituents on a phenazine-derived scaffold, C-C cross coupling was induced following thermal debromination. CAP-2 is polymerized from monomers that have been prepacked into layered structure (3-TBQP). It can be mechanically exfoliated into micrometer-sized ultrathin sheets that show sharp Raman peaks which reflect conformational ordering. CAP-2 has a dominant pore size of ∼0.8 nm; when applied as an asymmetric supercapacitor, it delivers a specific capacitance of 233 F g -1 at a current density of 1.0 A g -1 , and shows outstanding cycle performance.

Processable high temperature resistant polymer matrix materials

NASA Technical Reports Server (NTRS)

Serafini, T. T.

1975-01-01

A review is presented of studies conducted with addition-cured polyimides, giving particular attention to an improved method involving in situ polymerization of monomer reactants (PMR) on the surface of the reinforcing fibers. The studies show that the PMR approach provides a powerful method for fabricating high performance polymer matrix composites. Significant advantages of the PMR approach are related to the superior high temperature properties of the obtained material, lower cost, greater safety, and processing versatility.

Enhancing the Properties of Conductive Polymer Hydrogels by Freeze-Thaw Cycles for High-Performance Flexible Supercapacitors.

PubMed

Li, Wanwan; Lu, Han; Zhang, Ning; Ma, Mingming

2017-06-14

We report that a postsynthesis physical process (freeze-thaw cycles) can reform the microstructure of conductive polymer hydrogels from clustered nanoparticles to interconnected nanosheets, leading to enhanced mechanical and electrochemical properties. The polyaniline-poly(vinyl alcohol) hydrogel after five freeze-thaw cycles (PPH-5) showed remarkable tensile strength (16.3 MPa), large elongation at break (407%), and high electrochemical capacitance (1053 F·g -1 ). The flexible supercapacitor based on PPH-5 provided a large capacitance (420 mF·cm -2 and 210 F·g -1 ) and high energy density (18.7 W·h·kg -1 ), whose robustness was demonstrated by its 100% capacitance retention after 1000 galvanostatic charge-discharge cycles or after 1000 mechanical folding cycles. The outstanding performance enables PPH-5 based supercapacitor as a promising power device for flexible electronics, which also demonstrates the merit of freeze-thaw cycles for enhancing the performance of functional hydrogels.

A tough high performance composite matrix

NASA Technical Reports Server (NTRS)

Pater, Ruth H. (Inventor); Johnston, Norman J. (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 in the 200 to 300 C range. This resin has significantly improved toughness and microcracking resistance, excellent processability, mechanical performance and moisture and solvent resistances.

High Performance Electrocatalytic Reaction of Hydrogen and Oxygen on Ruthenium Nanoclusters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ye, Ruquan; Liu, Yuanyue; Peng, Zhiwei

2017-01-18

The development of catalytic materials for the hydrogen oxidation, hydrogen evolution, oxygen reduction or oxygen evolution reactions with high reaction rates and low overpotentials are key goals for the development of renewable energy. We report here Ru(0) nanoclusters supported on nitrogen-doped graphene as high-performance multifunctional catalysts for the hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR), showing activities similar to that of commercial Pt/C in alkaline solution. For HER performance in alkaline media, sample Ru/NG-750 reaches 10 mA cm-2 at an overpotential of 8 mV with a Tafel slope of 30 mV dec-1. The high HER performance in alkalinemore » solution is advantageous because most catalysts for ORR and oxygen evolution reaction (OER) also prefer alkaline solution environment whereas degrade in acidic electrolytes. For ORR performance, Ru/NG effectively catalyzes the conversion of O2 into OH- via a 4e process at a current density comparable to that of Pt/C. The unusual catalytic activities of Ru(0) nanoclusters reported here are important discoveries for the advancement of renewable energy conversion reactions.« less

High-density polymer microarrays: identifying synthetic polymers that control human embryonic stem cell growth.

PubMed

Hansen, Anne; Mjoseng, Heidi K; Zhang, Rong; Kalloudis, Michail; Koutsos, Vasileios; de Sousa, Paul A; Bradley, Mark

2014-06-01

The fabrication of high-density polymer microarray is described, allowing the simultaneous and efficient evaluation of more than 7000 different polymers in a single-cellular-based screen. These high-density polymer arrays are applied in the search for synthetic substrates for hESCs culture. Up-scaling of the identified hit polymers enables long-term cellular cultivation and promoted successful stem-cell maintenance. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

Novel hybrid columns made of ultra-high performance concrete and fiber reinforced polymers

NASA Astrophysics Data System (ADS)

Zohrevand, Pedram

The application of advanced materials in infrastructure has grown rapidly in recent years mainly because of their potential to ease the construction, extend the service life, and improve the performance of structures. Ultra-high performance concrete (UHPC) is one such material considered as a novel alternative to conventional concrete. The material microstructure in UHPC is optimized to significantly improve its material properties including compressive and tensile strength, modulus of elasticity, durability, and damage tolerance. Fiber-reinforced polymer (FRP) composite is another novel construction material with excellent properties such as high strength-to-weight and stiffness-to-weight ratios and good corrosion resistance. Considering the exceptional properties of UHPC and FRP, many advantages can result from the combined application of these two advanced materials, which is the subject of this research. The confinement behavior of UHPC was studied for the first time in this research. The stress-strain behavior of a series of UHPC-filled fiber-reinforced polymer (FRP) tubes with different fiber types and thicknesses were tested under uniaxial compression. The FRP confinement was shown to significantly enhance both the ultimate strength and strain of UHPC. It was also shown that existing confinement models are incapable of predicting the behavior of FRP-confined UHPC. Therefore, new stress-strain models for FRP-confined UHPC were developed through an analytical study. In the other part of this research, a novel steel-free UHPC-filled FRP tube (UHPCFFT) column system was developed and its cyclic behavior was studied. The proposed steel-free UHPCFFT column showed much higher strength and stiffness, with a reasonable ductility, as compared to its conventional reinforced concrete (RC) counterpart. Using the results of the first phase of column tests, a second series of UHPCFFT columns were made and studied under pseudo-static loading to study the effect of column

Vapor phase polymerization deposition of conducting polymer/graphene nanocomposites as high performance electrode materials.

PubMed

Yang, Yajie; Li, Shibin; Zhang, Luning; Xu, Jianhua; Yang, Wenyao; Jiang, Yadong

2013-05-22

In this paper, we report chemical vapor phase polymerization (VPP) deposition of novel poly(3,4-ethylenedioxythiophene) (PEDOT)/graphene nanocomposites as solid tantalum electrolyte capacitor cathode films. The PEDOT/graphene films were successfully prepared on porous tantalum pentoxide surface as cathode films through the VPP procedure. The results indicated that the high conductivity nature of PEDOT/graphene leads to the decrease of cathode films resistance and contact resistance between PEDOT/graphene and carbon paste. This nanocomposite cathode film based capacitor showed ultralow equivalent series resistance (ESR) ca. 12 mΩ and exhibited better capacitance-frequency performance than the PEDOT based capacitor. The leakage current investigation revealed that the device encapsulation process does not influence capacitor leakage current, indicating the excellent mechanical strength of PEDOT-graphene films. The graphene showed a distinct protection effect on the dielectric layer from possible mechanical damage. This high conductivity and mechanical strength graphene based conducting polymer nanocomposites indicated a promising application future for organic electrode materials.

Polymer-pyrolysis assisted synthesis of vanadium trioxide and carbon nanocomposites as high performance anode materials for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Dong, Yucheng; Ma, Ruguang; Hu, Mingjun; Cheng, Hua; Lee, Jong-Min; Li, Yang Yang; Zapien, Juan Antonio

2014-09-01

We present a simple polymer-pyrolysis assisted method to prepare vanadium trioxide and carbon nanocomposites as an advanced anode material for lithium-ion batteries. The as-prepared material deliver a superior battery performance with highly retained capacity of ∼780 mAh g-1 over 100 cycles at a current density of 200 mA g-1, showing excellent cyclic stability, and good rate capability. The improved electrochemical performance of vanadium trioxide and carbon nanocomposites electrode makes it promising as a suitable anode material for practical battery applications.

Preparing high-density polymer brushes by mechanically assisted polymer assembly (MAPA)

NASA Astrophysics Data System (ADS)

Wu, Tao; Efimenko, Kirill; Genzer, Jan

2001-03-01

We introduce a novel method of modifying the surface properties of materials. This technique, called MAPA (="mechanically assisted polymer assembly"), is based on: 1) chemically attaching polymerization initiators to the surface of an elastomeric network that has been previously stretched by a certain length, Δx, and 2) growing end-anchored macromolecules using surface initiated ("grafting from") atom transfer living radical polymerization. After the polymerization, the strain is removed from the substrate, which returns to its original size causing the grafted macromolecules to stretch away from the substrate and form a dense polymer brush. We demonstrate the feasibility of the MAPA method by preparing high-density polymer brushes of poly(acryl amide), PAAm. We show that, as expected, the grafting density of the PAAm brushes can be increased by increasing Δx. We demonstrate that polymer brushes with extremely high grafting densities can be successfully prepared by MAPA.

Numerical Simulation of Thermal Performance of Glass-Fibre-Reinforced Polymer

NASA Astrophysics Data System (ADS)

Zhao, Yuchao; Jiang, Xu; Zhang, Qilin; Wang, Qi

2017-10-01

Glass-Fibre-Reinforced Polymer (GFRP), as a developing construction material, has a rapidly increasing application in civil engineering especially bridge engineering area these years, mainly used as decorating materials and reinforcing bars for now. Compared with traditional construction material, these kinds of composite material have obvious advantages such as high strength, low density, resistance to corrosion and ease of processing. There are different processing methods to form members, such as pultrusion and resin transfer moulding (RTM) methods, which process into desired shape directly through raw material; meanwhile, GFRP, as a polymer composite, possesses several particular physical and mechanical properties, and the thermal property is one of them. The matrix material, polymer, performs special after heated and endue these composite material a potential hot processing property, but also a poor fire resistance. This paper focuses on thermal performance of GFRP as panels and corresponding researches are conducted. First, dynamic thermomechanical analysis (DMA) experiment is conducted to obtain the glass transition temperature (Tg) of the object GFRP, and the curve of bending elastic modulus with temperature is calculated according to the experimental data. Then compute and estimate the values of other various thermal parameters through DMA experiment and other literatures, and conduct numerical simulation under two condition respectively: (1) the heat transfer process of GFRP panel in which the panel would be heated directly on the surface above Tg, and the hot processing under this temperature field; (2) physical and mechanical performance of GFRP panel under fire condition. Condition (1) is mainly used to guide the development of high temperature processing equipment, and condition (2) indicates that GFRP’s performance under fire is unsatisfactory, measures must be taken when being adopted. Since composite materials’ properties differ from each other

Energy harvesting performance of piezoelectric ceramic and polymer nanowires.

PubMed

Crossley, Sam; Kar-Narayan, Sohini

2015-08-28

Energy harvesting from ubiquitous ambient vibrations is attractive for autonomous small-power applications and thus considerable research is focused on piezoelectric materials as they permit direct inter-conversion of mechanical and electrical energy. Nanogenerators (NGs) based on piezoelectric nanowires are particularly attractive due to their sensitivity to small-scale vibrations and may possess superior mechanical-to-electrical conversion efficiency when compared to bulk or thin-film devices of the same material. However, candidate piezoelectric nanowires have hitherto been predominantly analyzed in terms of NG output (i.e. output voltage, output current and output power density). Surprisingly, the corresponding dynamical properties of the NG, including details of how the nanowires are mechanically driven and its impact on performance, have been largely neglected. Here we investigate all realizable NG driving contexts separately involving inertial displacement, applied stress T and applied strain S, highlighting the effect of driving mechanism and frequency on NG performance in each case. We argue that, in the majority of cases, the intrinsic high resonance frequencies of piezoelectric nanowires (∼tens of MHz) present no barrier to high levels of NG performance even at frequencies far below resonance (<1 kHz) typically characteristic of ambient vibrations. In this context, we introduce vibrational energy harvesting (VEH) coefficients ηS and ηT, based on intrinsic materials properties, for comparing piezoelectric NG performance under strain-driven and stress-driven conditions respectively. These figures of merit permit, for the first time, a general comparison of piezoelectric nanowires for NG applications that takes into account the nature of the mechanical excitation. We thus investigate the energy harvesting performance of prototypical piezoelectric ceramic and polymer nanowires. We find that even though ceramic and polymer nanowires have been found, in

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.

Role of the Group 2 Mrp sodium/proton antiporter in rapid response to high alkaline shock in the alkaline- and salt-tolerant Dietzia sp. DQ12-45-1b.

PubMed

Fang, Hui; Qin, Xiao-Yu; Zhang, Kai-Duan; Nie, Yong; Wu, Xiao-Lei

2018-04-01

The six- and seven-subunit Na + /H + antiporters (Mrp) are widely distributed in bacteria. They are reported to be integral for pH homeostasis in alkaliphilic bacteria when adapting to high pH environments. In this study, operons encoding for the six-subunit Na + /H + antiporters were found in the genomes of all studied Dietzia strains, which have different alkaline-resistant abilities. Disruption of the operon in the strain Dietzia sp. DQ12-45-1b which leads to declined growth in presence of hypersaline and alkaline conditions suggested that the six-subunit Na + /H + antiporter played an important role in hypersaline and alkaline resistance. Although the complexes DqMrp from DQ12-45-1b (strain with high alkaline resistance) and DaMrp from D. alimentaria 72 T (strain with low alkaline resistance) displayed Na + (Li + )/H + antiport activities, they functioned optimally at different pH levels (9.0 for DQ12-45-1b and 8.0 for 72 T ). While both antiporters functioned properly to protect Escherichia coli cells from salt shock, only the DqMrp-containing strain survived the high alkaline shock. Furthermore, real-time PCR results showed that the expression of mrpA and mrpD induced only immediately after DQ12-45-1b cells were subjected to the alkaline shock. These results suggested that the expression of DqMrp might be induced by a pH gradient across the cell membrane, and DqMrp mainly functioned at an early stage to respond to the alkaline shock.

The impact of pH on floc structure characteristic of polyferric chloride in a low DOC and high alkalinity surface water treatment.

PubMed

Cao, Baichuan; Gao, Baoyu; Liu, Xin; Wang, Mengmeng; Yang, Zhonglian; Yue, Qinyan

2011-11-15

The adjustment of pH is an important way to enhance removal efficiency in coagulation units, and in this process, the floc size, strength and structure can be changed, influencing the subsequent solid/liquid separation effect. In this study, an inorganic polymer coagulant, polyferric chloride (PFC) was used in a low dissolved organic carbon (DOC) and high alkalinity surface water treatment. The influence of coagulation pH on removal efficiency, floc growth, strength, re-growth capability and fractal dimension was examined. The optimum dosage was predetermined as 0.150 mmol/L, and excellent particle and organic matter removal appeared in the pH range of 5.50-5.75. The structure characteristics of flocs formed under four pH conditions were investigated through the analysis of floc size, effect of shear and particle scattering properties by a laser scattering instrument. The results indicated that flocs formed at neutral pH condition gave the largest floc size and the highest growth rate. During the coagulation period, the fractal dimension of floc aggregates increased in the first minutes and then decreased and larger flocs generally had smaller fractal dimensions. The floc strength, which was assessed by the relationship of floc diameter and velocity gradient, decreased with the increase of coagulation pH. Flocs formed at pH 4.00 had better recovery capability when exposed to lower shear forces, while flocs formed at neutral and alkaline conditions had better performance under higher shear forces. Copyright © 2011 Elsevier Ltd. All rights reserved.

Alkaline quinone flow battery.

PubMed

Lin, Kaixiang; Chen, Qing; Gerhardt, Michael R; Tong, Liuchuan; Kim, Sang Bok; Eisenach, Louise; Valle, Alvaro W; Hardee, David; Gordon, Roy G; Aziz, Michael J; Marshak, Michael P

2015-09-25

Storage of photovoltaic and wind electricity in batteries could solve the mismatch problem between the intermittent supply of these renewable resources and variable demand. Flow batteries permit more economical long-duration discharge than solid-electrode batteries by using liquid electrolytes stored outside of the battery. We report an alkaline flow battery based on redox-active organic molecules that are composed entirely of Earth-abundant elements and are nontoxic, nonflammable, and safe for use in residential and commercial environments. The battery operates efficiently with high power density near room temperature. These results demonstrate the stability and performance of redox-active organic molecules in alkaline flow batteries, potentially enabling cost-effective stationary storage of renewable energy. Copyright © 2015, American Association for the Advancement of Science.

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

High sulfur-containing carbon polysulfide polymer as a novel cathode material for lithium-sulfur battery.

PubMed

Zhang, Yiyong; Peng, Yueying; Wang, Yunhui; Li, Jiyang; Li, He; Zeng, Jing; Wang, Jing; Hwang, Bing Joe; Zhao, Jinbao

2017-09-12

The lithium-sulfur battery, which offers a high energy density and is environmental friendly, is a promising next generation of rechargeable energy storage system. However, despite these attractive attributes, the commercialization of lithium-sulfur battery is primarily hindered by the parasitic reactions between the Li metal anode and dissolved polysulfide species from the cathode during the cycling process. Herein, we synthesize the sulfur-rich carbon polysulfide polymer and demonstrate that it is a promising cathode material for high performance lithium-sulfur battery. The electrochemical studies reveal that the carbon polysulfide polymer exhibits superb reversibility and cycle stability. This is due to that the well-designed structure of the carbon polysulfide polymer has several advantages, especially, the strong chemical interaction between sulfur and the carbon framework (C-S bonds) inhibits the shuttle effect and the π electrons of the carbon polysulfide compound enhance the transfer of electrons and Li + . Furthermore, as-prepared carbon polysulfide polymer-graphene hybrid cathode achieves outstanding cycle stability and relatively high capacity. This work highlights the potential promise of the carbon polysulfide polymer as the cathode material for high performance lithium-sulfur battery.

Investigation of the degradation of different nickel anode types for alkaline fuel cells (AFCs)

NASA Astrophysics Data System (ADS)

Gülzow, E.; Schulze, M.; Steinhilber, G.

Alkaline fuel cells (AFCs) have the opportunity of becoming important for mobile energy systems as, in contrast to other low temperature fuel cells, the alkaline type requires neither noble metal catalysts nor an expensive polymer electrolyte. In AFCs, nickel is used as anode catalyst in gas diffusion electrodes. The metal catalyst was mixed with polytetraflourethylene (PTFE) as organic binder in a knife mile and rolled onto a metal web in a calendar to prepare the electrode. After an activation process with hydrogen evolution at 5 mA/cm 2 for 18 h, the electrodes were stressed at constant loading in a half cell equipment. During the fuel cell operation, the electrochemical performance decreased due to changes of the polymer (PTFE) and of the metal particles in the electrode, which is described in detail in another paper. In this study, three types of electrodes were investigated. The first type of electrode is composed of pure Raney-nickel and PTFE powder, the nickel particles in the second electrode type were selected according to particle size and in the third electrode copper powder was added to the nickel powder not selected by size. The size selected nickel particles show a better electrochemical performance related to the non-selected catalyst, but due to the electrochemically induced disintegration of the nickel particles the electrochemical performance decreases stronger. The copper powder in the third electrode is added to improve the electronic conductivity of the nickel catalyst, but the copper is not stable under the electrochemical conditions in fuel cell operation. With all three anode types long-term experiments have been performed. The electrodes have been characterized after the electrochemical stressing to investigate the degradation processes.

High-resolution Imaging of pH in Alkaline Sediments and Water Based on a New Rapid Response Fluorescent Planar Optode

NASA Astrophysics Data System (ADS)

Han, Chao; Yao, Lei; Xu, Di; Xie, Xianchuan; Zhang, Chaosheng

2016-05-01

A new dual-lumophore optical sensor combined with a robust RGB referencing method was developed for two-dimensional (2D) pH imaging in alkaline sediments and water. The pH sensor film consisted of a proton-permeable polymer (PVC) in which two dyes with different pH sensitivities and emission colors: (1) chloro phenyl imino propenyl aniline (CPIPA) and (2) the coumarin dye Macrolex® fluorescence yellow 10 GN (MFY-10 GN) were entrapped. Calibration experiments revealed the typical sigmoid function and temperature dependencies. This sensor featured high sensitivity and fast response over the alkaline working ranges from pH 7.5 to pH 10.5. Cross-sensitivity towards ionic strength (IS) was found to be negligible for freshwater when IS <0.1 M. The sensor had a spatial resolution of approximately 22 μm and aresponse time of <120 s when going from pH 7.0 to 9.0. The feasibility of the sensor was demonstrated using the pH microelectrode. An example of pH image obtained in the natrual freshwater sediment and water associated with the photosynthesis of Vallisneria spiral species was also presented, suggesting that the sensor held great promise for the field applications.

High-resolution Imaging of pH in Alkaline Sediments and Water Based on a New Rapid Response Fluorescent Planar Optode

PubMed Central

Han, Chao; Yao, Lei; Xu, Di; Xie, Xianchuan; Zhang, Chaosheng

2016-01-01

A new dual-lumophore optical sensor combined with a robust RGB referencing method was developed for two-dimensional (2D) pH imaging in alkaline sediments and water. The pH sensor film consisted of a proton-permeable polymer (PVC) in which two dyes with different pH sensitivities and emission colors: (1) chloro phenyl imino propenyl aniline (CPIPA) and (2) the coumarin dye Macrolex® fluorescence yellow 10 GN (MFY-10 GN) were entrapped. Calibration experiments revealed the typical sigmoid function and temperature dependencies. This sensor featured high sensitivity and fast response over the alkaline working ranges from pH 7.5 to pH 10.5. Cross-sensitivity towards ionic strength (IS) was found to be negligible for freshwater when IS <0.1 M. The sensor had a spatial resolution of approximately 22 μm and aresponse time of <120 s when going from pH 7.0 to 9.0. The feasibility of the sensor was demonstrated using the pH microelectrode. An example of pH image obtained in the natrual freshwater sediment and water associated with the photosynthesis of Vallisneria spiral species was also presented, suggesting that the sensor held great promise for the field applications. PMID:27199163

Solution-processable ambipolar diketopyrrolopyrrole-selenophene polymer with unprecedentedly high hole and electron mobilities.

PubMed

Lee, Junghoon; Han, A-Reum; Kim, Jonggi; Kim, Yiho; Oh, Joon Hak; Yang, Changduk

2012-12-26

There is a fast-growing demand for polymer-based ambipolar thin-film transistors (TFTs), in which both n-type and p-type transistor operations are realized in a single layer, while maintaining simplicity in processing. Research progress toward this end is essentially fueled by molecular engineering of the conjugated backbones of the polymers and the development of process architectures for device fabrication, which has recently led to hole and electron mobilities of more than 1.0 cm(2) V(-1) s(-1). However, ambipolar polymers with even higher performance are still required. By taking into account both the conjugated backbone and side chains of the polymer component, we have developed a dithienyl-diketopyrrolopyrrole (TDPP) and selenophene containing polymer with hybrid siloxane-solubilizing groups (PTDPPSe-Si). A synergistic combination of rational polymer backbone design, side-chain dynamics, and solution processing affords an enormous boost in ambipolar TFT performance, resulting in unprecedentedly high hole and electron mobilities of 3.97 and 2.20 cm(2) V(-1) s(-1), respectively.

Oxidation catalysts on alkaline earth supports

DOEpatents

Mohajeri, Nahid

2017-03-21

An oxidation catalyst includes a support including particles of an alkaline earth salt, and first particles including a palladium compound on the support. The oxidation catalyst can also include precious metal group (PMG) metal particles in addition to the first particles intermixed together on the support. A gas permeable polymer that provides a continuous phase can completely encapsulate the particles and the support. The oxidation catalyst may be used as a gas sensor, where the first particles are chemochromic particles.

Rheological properties of polymer melts with high elasticity

NASA Astrophysics Data System (ADS)

Feranc, Jozef; Matvejová, Martina; Alexy, Pavol; Pret'o, Jozef; Hronkovič, Ján

2017-05-01

In the recent years efforts to complex description of the rheological characteristic increase even in the case of polymeric blends with high part of elastic deformation. However, unlike the most thermoplastic these blends have a certain specific features. Besides the already mentioned the higher part of elastic deformation it is especially higher viscosity, which are shown mainly for the measurement in the range of high shear rates. For this reason, the presented work is focused on the description of measurement methodology for blends with high part of elastic deformation using capillary rheometer. The measurements were carried out on a commercial polymer blend with trade name A517 based on rubbery polymer. Capillary rheometer Gottfert RG 75 was used, with diameter of chamber 15 mm. Measurements were performed using capillaries with different ratio of length/diameter at temperature 100°C. Because of existence elastic part of deformation, it is not possible to achieve a steady state pressure using measurements at constant volumetric flow at high shear rates. Therefore we decided to measure the flow characteristic using isobaric mode.

High Performance Variable Emittance Devices for Spacecraft Application Based on Conducting Polymers Coupled with Ionic Liquids

NASA Astrophysics Data System (ADS)

Chandrasekhar, Prasanna; Zay, Brian J.; Barbolt, Scott; Werner, Robert; Birur, Gajanana C.; Paris, Anthony

2009-03-01

This contribution describes the fabrication, function and performance of thin-film variable emittance electrochromic skins fabricated using poly(aniline) as the conducting polymer (CP), a long-chain polymeric dopant, and an ionic liquid as electrolyte. The ionic electrolyte allows operation in space vacuum without any seals. A unique, space-durable coating applied to the external surface of the skins drastically lowers the solar absorptance of the skins, such that in their dark (highly emissive) electrochromic state, it is no more than 0.44, whilst in their light electrochromic state, it is ca. 0.3. Data presented show tailorable, variations from 0.19 to 0.90, ∀(s)<0.3, and nearly indefinite cyclability. Extended thermal vacuum, atomic-O, micrometeoroid, VUV and other studies show excellent space durability. Performance of a doughnut-shaped skin designed for a specific micro-spacecraft is also described.

High performance shape memory polymer networks based on rigid nanoparticle cores

PubMed Central

Song, Jie

2010-01-01

Smart materials that can respond to external stimuli are of widespread interest in biomedical science. Thermal-responsive shape memory polymers, a class of intelligent materials that can be fixed at a temporary shape below their transition temperature (Ttrans) and thermally triggered to resume their original shapes on demand, hold great potential as minimally invasive self-fitting tissue scaffolds or implants. The intrinsic mechanism for shape memory behavior of polymers is the freezing and activation of the long-range motion of polymer chain segments below and above Ttrans, respectively. Both Ttrans and the extent of polymer chain participation in effective elastic deformation and recovery are determined by the network composition and structure, which are also defining factors for their mechanical properties, degradability, and bioactivities. Such complexity has made it extremely challenging to achieve the ideal combination of a Ttrans slightly above physiological temperature, rapid and complete recovery, and suitable mechanical and biological properties for clinical applications. Here we report a shape memory polymer network constructed from a polyhedral oligomeric silsesquioxane nanoparticle core functionalized with eight polyester arms. The cross-linked networks comprising this macromer possessed a gigapascal-storage modulus at body temperature and a Ttrans between 42 and 48 °C. The materials could stably hold their temporary shapes for > 1 year at room temperature and achieve full shape recovery ≤ 51 °C in a matter of seconds. Their versatile structures allowed for tunable biodegradability and biofunctionalizability. These materials have tremendous promise for tissue engineering applications. PMID:20375285

All-Polymer Solar Cell Performance Optimized via Systematic Molecular Weight Tuning of Both Donor and Acceptor Polymers.

PubMed

Zhou, Nanjia; Dudnik, Alexander S; Li, Ting I N G; Manley, Eric F; Aldrich, Thomas J; Guo, Peijun; Liao, Hsueh-Chung; Chen, Zhihua; Chen, Lin X; Chang, Robert P H; Facchetti, Antonio; Olvera de la Cruz, Monica; Marks, Tobin J

2016-02-03

The influence of the number-average molecular weight (Mn) on the blend film morphology and photovoltaic performance of all-polymer solar cells (APSCs) fabricated with the donor polymer poly[5-(2-hexyldodecyl)-1,3-thieno[3,4-c]pyrrole-4,6-dione-alt-5,5-(2,5-bis(3-dodecylthiophen-2-yl)thiophene)] (PTPD3T) and acceptor polymer poly{[N,N'-bis(2-octyldodecyl)naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5'-(2,2'-bithiophene)} (P(NDI2OD-T2); N2200) is systematically investigated. The Mn effect analysis of both PTPD3T and N2200 is enabled by implementing a polymerization strategy which produces conjugated polymers with tunable Mns. Experimental and coarse-grain modeling results reveal that systematic Mn variation greatly influences both intrachain and interchain interactions and ultimately the degree of phase separation and morphology evolution. Specifically, increasing Mn for both polymers shrinks blend film domain sizes and enhances donor-acceptor polymer-polymer interfacial areas, affording increased short-circuit current densities (Jsc). However, the greater disorder and intermixed feature proliferation accompanying increasing Mn promotes charge carrier recombination, reducing cell fill factors (FF). The optimized photoactive layers exhibit well-balanced exciton dissociation and charge transport characteristics, ultimately providing solar cells with a 2-fold PCE enhancement versus devices with nonoptimal Mns. Overall, it is shown that proper and precise tuning of both donor and acceptor polymer Mns is critical for optimizing APSC performance. In contrast to reports where maximum power conversion efficiencies (PCEs) are achieved for the highest Mns, the present two-dimensional Mn optimization matrix strategy locates a PCE "sweet spot" at intermediate Mns of both donor and acceptor polymers. This study provides synthetic methodologies to predictably access conjugated polymers with desired Mn and highlights the importance of optimizing Mn for both polymer

All-Polymer Solar Cell Performance Optimized via Systematic Molecular Weight Tuning of Both Donor and Acceptor Polymers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Nanjia; Dudnik, Alexander S.; Li, Ting I. N. G.

2015-12-31

ABSTRACT: The influence of the number-average molecular weight (Mn) on the blend film morphology and photovoltaic performance of all-polymer solar cells (APSCs) fabricated with the donor polymer poly[5-(2-hexyldodecyl)-1,3-thieno[3,4- c]pyrrole-4,6-dione-alt-5,5-(2,5-bis(3-dodecylthiophen-2-yl)- thiophene)] (PTPD3T) and acceptor polymer poly{[N,N'- bis(2-octyldodecyl)naphthalene-1,4,5,8-bis(dicarboximide)- 2,6-diyl]-alt-5,5'-(2,2'-bithiophene)} (P(NDI2OD-T2); N2200) is systematically investigated. The M n effect analysis of both PTPD3T and N2200 is enabled by implementing a polymerization strategy which produces conjugated polymers with tunable M ns. Experimental and coarse-grain modeling results reveal that systematic M n variation greatly influences both intrachain and interchain interactions and ultimately the degree of phase separation and morphology evolution. Specifically, increasing M n formore » both polymers shrinks blend film domain sizes and enhances donor-acceptor polymer-polymer interfacial areas, affording increased short-circuit current densities (J sc). However, the greater disorder and intermixed feature proliferation accompanying increasing M n promotes charge carrier recombination, reducing cell fill factors (FF). The optimized photoactive layers exhibit well-balanced exciton dissociation and charge transport characteristics, ultimately providing solar cells with a 2-fold PCE enhancement versus devices with nonoptimal M ns. Overall, it is shown that proper and precise tuning of both donor and acceptor polymer M ns is critical for optimizing APSC performance. In contrast to reports where maximum power conversion efficiencies (PCEs) are achieved for the highest M ns, the present two-dimensional M n optimization matrix strategy locates a PCE “sweet spot” at intermediate Mns of both donor and acceptor polymers. This study provides synthetic methodologies to predictably access conjugated polymers with desired M n and highlights the importance of

Polymer dots grafted TiO2 nanohybrids as high performance visible light photocatalysts.

PubMed

Li, Gen; Wang, Feng; Liu, Peng; Chen, Zheming; Lei, Ping; Xu, Zhongshan; Li, Zengxi; Ding, Yanfen; Zhang, Shimin; Yang, Mingshu

2018-04-01

As a new member of carbon dots (CDs), Polymer dots (PDs) prepared by hydrothermal treatment of polymers, usually consist of the carbon core and the connected partially degraded polymer chains. This type of CDs might possess aqueous solubility, non-toxicity, excellent stability against photo-bleaching and high visible light activity. In this research, PDs were prepared by a moderate hydrothermal treatment of polyvinyl alcohol, and PDs grafted TiO 2 (PDs-TiO 2 ) nanohybrids with TiOC bonds were prepared by a facile in-situ hydrothermal treatment of PDs and Ti (SO 4 ) 2 . Under visible light irradiation, the PDs-TiO 2 demonstrate excellent photocatalytic activity for methyl orange degradation, and the photocatalytic rate constant of PDs-TiO 2 is 3.6 and 9.5 times higher than that of pure TiO 2 and commercial P25, respectively. In addition, the PDs-TiO 2 exhibit good recycle stability under UV-Vis light irradiation. The interfacial TiOC bonds and the π-conjugated structures in PDs-TiO 2 can act as the pathways to quickly transfer the excited electrons between PDs and TiO 2 , therefore contribute to the excellent photocatalytic activity. Copyright © 2018 Elsevier Ltd. All rights reserved.

Alkaline treatment of high-solids sludge and its application to anaerobic digestion.

PubMed

Li, Chenchen; Li, Huan; Zhang, Yuyao

2015-01-01

High-solids anaerobic digestion is a promising new process for sludge reduction and bioenergy recovery, requiring smaller digestion tanks and less energy for heating, but a longer digestion time, than traditional low-solids anaerobic digestion. To accelerate this process, alkaline sludge disintegration was tested as a pretreatment method for anaerobic digestion of high-solids sludge. The results showed that alkaline treatment effectively disintegrated both low-solids sludge and high-solids sludge, and treatment duration of 30 min was the most efficient. The relation between sludge disintegration degree and NaOH dose can be described by a transmutative power function model. At NaOH dose lower than 0.2 mol/L, sludge disintegration degree remained virtually unchanged when sludge total solids (TS) content increased from 2.0 to 11.0%, and decreased only slightly when sludge TS increased to 14.2%. Although high-solids sludge required a slightly higher molarity of NaOH to reach the same disintegration level of low-solids sludge, the required mass of NaOH actually decreased due to sludge thickening. From the view of NaOH consumption, sludge TS of 8-12% and a NaOH dose of 0.05 mol/L were optimum conditions for alkaline pretreatment, which resulted in a slight increase in accumulative biogas yield, but a decrease by 24-29% in digestion time during the subsequent anaerobic digestion.

Is alkaline phosphatase the smoking gun for highly refractory primitive leukemic cells?

PubMed Central

Rico, Laura G.; Juncà, Jordi; Ward, Mike D.; Bradford, Jolene; Petriz, Jordi

2016-01-01

With the aim to detect candidate malignant primitive progenitor populations, we modified an original alkaline phosphatase (ALP) stem cell detection method based on the identification of alkaline phosphatase fluorescent cells in combination with flow cytometry immunophenotyping. Over a period of one year, we have been using this technique to study its activity in patients with leukemia and lymphoma, showing that changes in the alkaline phosphatase levels can be used to detect rare populations of highly refractory malignant cells. By screening different blood cancers, we have observed that this activity is not always restricted to CD34+ leukemic cells, and can be overexpressed in CD34 negative leukemia. We have verified that this method gives accurate and reproducible measurements and our preliminary results suggest that CD34+/ALPhigh cells appear to sustain leukemogenesis over time. PMID:27732563

High performance inkjet-printed metal oxide thin film transistors via addition of insulating polymer with proper molecular weight

NASA Astrophysics Data System (ADS)

Sun, Dawei; Chen, Cihai; Zhang, Jun; Wu, Xiaomin; Chen, Huipeng; Guo, Tailiang

2018-01-01

Fabrication of metal oxide thin film transistor (MOTFT) arrays using the inkjet printing process has caused tremendous interest for low-cost and large-area flexible electronic devices. However, the inkjet-printed MOTFT arrays usually exhibited a non-uniform geometry due to the coffee ring effect, which restricted their commercial application. Therefore, in this work, a strategy is reported to control the geometry and enhance device performance of inkjet-printed MOTFT arrays by the addition of an insulating polymer to the precursor solution prior to film deposition. Moreover, the impact of the polymer molecular weight (MW) on the geometry, chemical constitution, crystallization, and MOTFT properties of inkjet-printed metal oxide depositions was investigated. The results demonstrated that with an increase of MW of polystyrene (PS) from 2000 to 200 000, the coffee ring was gradually faded and the coffee ring effect was completely eliminated when MW reached 200 000, which is associated with the enhanced viscosity with the insulating polymer, providing a high resistance to the outward capillary flow, which facilitated the depinning of the contact line, leading to the elimination of the coffee ring. More importantly, the carrier mobility increased significantly from 4.2 cm2 V-1 s-1 up to 13.7 cm2 V-1 s-1 as PS MW increased from 2000 to 200 000, which was about 3 times that of the pristine In2O3 TFTs. Grazing incidence X-ray diffraction and X-ray photoelectron spectroscopy results indicated that PS doping of In2O3 films not only frustrated crystallization but also altered chemical constitution by enhancing the formation of the M-O structure, both of which facilitated the carrier transport. These results demonstrated that the simple polymer additive process provides a promising method that can efficiently control the geometry of MO arrays during inkjet printing and maximize the device performance of MOTFT arrays, which showed great potential for the application in next

Electrochemical kinetic and mass transfer model for direct ethanol alkaline fuel cell (DEAFC)

NASA Astrophysics Data System (ADS)

Abdullah, S.; Kamarudin, S. K.; Hasran, U. A.; Masdar, M. S.; Daud, W. R. W.

2016-07-01

A mathematical model is developed for a liquid-feed DEAFC incorporating an alkaline anion-exchange membrane. The one-dimensional mass transport of chemical species is modelled using isothermal, single-phase and steady-state assumptions. The anode and cathode electrochemical reactions use the Tafel kinetics approach, with two limiting cases, for the reaction order. The model fully accounts for the mixed potential effects of ethanol oxidation at the cathode due to ethanol crossover via an alkaline anion-exchange membrane. In contrast to a polymer electrolyte membrane model, the current model considers the flux of ethanol at the membrane as the difference between diffusive and electroosmotic effects. The model is used to investigate the effects of the ethanol and alkali inlet feed concentrations at the anode. The model predicts that the cell performance is almost identical for different ethanol concentrations at a low current density. Moreover, the model results show that feeding the DEAFC with 5 M NaOH and 3 M ethanol at specific operating conditions yields a better performance at a higher current density. Furthermore, the model indicates that crossover effects on the DEAFC performance are significant. The cell performance decrease from its theoretical value when a parasitic current is enabled in the model.

Superwettability-Induced Confined Reaction toward High-Performance Flexible Electrodes.

PubMed

Xiong, Weiwei; Liu, Hongliang; Zhou, Yahong; Ding, Yi; Zhang, Xiqi; Jiang, Lei

2016-05-18

To find a general strategy to realize confinement of the conductive layer for high-performance flexible electrodes, with improved interfacial adhesion and high conductivity, is of important scientific significance. In this work, superwettability-induced confined reaction is used to fabricate high-performance flexible Ag/polymer electrodes, showing significantly improved silver conversion efficiency and interfacial adhesion. The as-prepared flexible electrodes by superhydrophilic polymeric surface under oil are highly conductive with an order of magnitude higher than the Ag/polymer electrodes obtained from original polymeric surface. The high conductivity achieved via superhydrophilic confinement is ascribed to the fact that the superhydrophilic polymeric surface can enhance the reaction rate of silver deposition and reduce the size of silver nanoparticles to achieve the densest packing. This new approach will provide a simple method to fabricate flexible and highly conductive Ag/polymer electrodes with excellent adhesion between the conductive layer and the substrate, and can be extended to other metal/polymeric electrodes or alloy/polymeric electrodes.

Extrudable polymer-polymer composites based on ultra-high molecular weight polyethylene

NASA Astrophysics Data System (ADS)

Panin, S. V.; Kornienko, L. A.; Alexenko, V. O.; Buslovich, D. G.; Dontsov, Yu. V.

2017-12-01

Mechanical and tribotechnical characteristics of polymer-polymeric composites of UHMWPE are studied with the aim of developing extrudable, wear-resistant, self-lubricant polymer mixtures for Additive Manufacturing (AM). The motivation of the study is their further application as feedstocks for 3D printing. Blends of UHMWPE with graft- and block copolymers of low-density polyethylene (HDPE-g-VTMS, HDPE-g-SMA, HDPE-b-EVA), polypropylene (PP), block copolymers of polypropylene and polyamide with linear low density polyethylene (PP-b-LLDPE, PA-b-LLDPE), as well as cross-linked polyethylene (PEX-b), are examined. The choice of compatible polymer components for an ultra- high molecular weight matrix for increasing processability (extrudability) is motivated by the search for commercially available and efficient additives aimed at developing wear-resistant extrudable polymer composites for additive manufacturing. The extrudability, mechanical properties and wear resistance of UHMWPE-based polymer-polymeric composites under sliding friction with different velocities and loads are studied.

Preparation of highly thermally stable and conductive Schiff base polymer: Molecular weight monitoring and investigation of antimicrobial properties

NASA Astrophysics Data System (ADS)

Yılmaz Baran, Nuray; Saçak, Mehmet

2018-07-01

A novel thermally stable polyazomethine with phenol group, Poly(4-[[4-(dimethylamino)benzylidene]amino]phenol) P(4-DBAP), was synthesized from 4-[[4-(dimethylamino)benzylidene]amino]phenol) (4-DBAP) in aqueous alkaline medium via oxidative polycondensation with NaOCl, H2O2, and O2 oxidants. The change of the yield and molecular weight distribution of P(4-DBAP) with oxidant type and concentration, monomer concentration, and polymerization temperature and time were analyzed. The structures of the monomer and polymer were confirmed by UV-Vis, FTIR, 1H-NMR, 13C-NMR and TGA techniques. The conductivity value of the polymer which was doped with iodine vapor for 24 h was reached 3.2 × 10-5 S/cm and 1.1 × 10-4 S/cm values by increasing 107 and 108 folds compared to the initial conductivity value at 20 °C and 60 °C, respectively. This conductivity value which was measured at 20 °C is the highest value reported in the literature for polyazomethines having phenol group in such a short time and at low temperature. Moreover, antimicrobial activity test was performed for 4-DBAP and P(4-DBAP) against Sarcina lutea, Enterobacter aerogenes, Escherichia coli, Enterococcus Feacalis, Klebsiella pneumoniae, Bacillus subtilis bacteria, and Candida albicans and Saccharomyces cerevisiae fungi. Although both monomer and polymer showed antibacterial activity, the polymer was more efficient compared to the monomer.

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.

All-Polymer Solar Cell Performance Optimized via Systematic Molecular Weight Tuning of Both Donor and Acceptor Polymers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Nanjia; Dudnik, Alexander S.; Li, Ting I. N. G.

2016-01-21

The influence of the number-average molecular weight (Mn) on the blend film morphology and photovoltaic performance of all-polymer solar cells (APSCs) fabricated with the donor polymer poly[5-(2-hexyldodecyl)-1,3-thieno[3,4-c]pyrrole-4,6-dione-alt-5,5-(2,5-bis(3-dodecylthiophen-2-yl)thiophene)] (PTPD3T) and acceptor polymer poly{[N,N'-bis(2-octyldodecyl)naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5'-(2,2'-bithiophene)} (P(NDI2OD-T2); N2200) is systematically investigated. The Mn effect analysis of both PTPD3T and N2200 is enabled by implementing a polymerization strategy which produces conjugated polymers with tunable Mns. Experimental and coarse-grain modeling results reveal that systematic Mn variation greatly influences both intrachain and interchain interactions and ultimately the degree of phase separation and morphology evolution. Specifically, increasing Mn for both polymers shrinks blend film domain sizes and enhancesmore » donor–acceptor polymer–polymer interfacial areas, affording increased short-circuit current densities (Jsc). However, the greater disorder and intermixed feature proliferation accompanying increasing Mn promotes charge carrier recombination, reducing cell fill factors (FF). The optimized photoactive layers exhibit well-balanced exciton dissociation and charge transport characteristics, ultimately providing solar cells with a 2-fold PCE enhancement versus devices with nonoptimal Mns. Overall, it is shown that proper and precise tuning of both donor and acceptor polymer Mns is critical for optimizing APSC performance. In contrast to reports where maximum power conversion efficiencies (PCEs) are achieved for the highest Mns, the present two-dimensional Mn optimization matrix strategy locates a PCE “sweet spot” at intermediate Mns of both donor and acceptor polymers. This study provides synthetic methodologies to predictably access conjugated polymers with desired Mn and highlights the importance of optimizing Mn for

High performance dielectric materials development

NASA Astrophysics Data System (ADS)

Piche, Joe; Kirchner, Ted; Jayaraj, K.

1994-09-01

The mission of polymer composites materials technology is to develop materials and processing technology to meet DoD and commercial needs. The following are outlined in this presentation: high performance capacitors, high temperature aerospace insulation, rationale for choosing Foster-Miller (the reporting industry), the approach to the development and evaluation of high temperature insulation materials, and the requirements/evaluation parameters. Supporting tables and diagrams are included.

High performance dielectric materials development

NASA Technical Reports Server (NTRS)

Piche, Joe; Kirchner, Ted; Jayaraj, K.

1994-01-01

The mission of polymer composites materials technology is to develop materials and processing technology to meet DoD and commercial needs. The following are outlined in this presentation: high performance capacitors, high temperature aerospace insulation, rationale for choosing Foster-Miller (the reporting industry), the approach to the development and evaluation of high temperature insulation materials, and the requirements/evaluation parameters. Supporting tables and diagrams are included.

Incorporation of ionic liquid into porous polymer monoliths to enhance the separation of small molecules in reversed-phase high-performance liquid chromatography.

PubMed

Wang, Jiafei; Bai, Ligai; Wei, Zhen; Qin, Junxiao; Ma, Yamin; Liu, Haiyan

2015-06-01

An ionic liquid was incorporated into the porous polymer monoliths to afford stationary phases with enhanced chromatographic performance for small molecules in reversed-phase high-performance liquid chromatography. The effect of the ionic liquid in the polymerization mixture on the performance of the monoliths was studied in detail. While monoliths without ionic liquid exhibited poor resolution and low efficiency, the addition of ionic liquid to the polymerization mixture provides highly increased resolution and high efficiency. The chromatographic performances of the monoliths were demonstrated by the separations of various small molecules including aromatic hydrocarbons, isomers, and homologues using a binary polar mobile phase. The present column efficiency reached 27 000 plates/m, which showed that the ionic liquid monoliths are alternative stationary phases in the separation of small molecules by high-performance liquid chromatography. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electromembrane recycling of highly mineralized alkaline blowdown water from evaporative water treatment plants at thermal power stations

NASA Astrophysics Data System (ADS)

Chichirova, N. D.; Chichirov, A. A.; Lyapin, A. I.; Minibaev, A. I.; Silov, I. Yu.; Tolmachev, L. I.

2016-12-01

Thermal power stations (TPS) are the main source of highly mineralized effluents affecting the environment. An analysis of their water systems demonstrates that alkaline effluents prevail at TPSs. Extraction of an alkali from highly mineralized effluents can make the recycling of effluents economically feasible. A method is proposed of electromembrane recycling of liquid alkaline highly mineralized wastes from TPSs. The process includes electromembrane apparatuses of two types, namely, a diffusion dialysis extractor (DDE) intended for extraction of the alkali from a highly mineralized solution having a complex composition and an electrodialysis concentrator for increasing the concentration of the extracted solution to a value suitable for use in water treatment plants at TPSs. For implementation of the first process (i.e. the extraction of alkali from alkaline-salt solution) various membranes from various manufacturers were studied: CM-PAD and AM-PAD (Ralex, Czechia), MK-40, MA-40, MA-41, MA-414, and MB-2 (OOO OKhK "Shchekinoazot", Russia), AR103-QDF and CR61-CMP (Ionies Inc., USA). The experiments demonstrate that the acceptable degree of separation of the alkali and the salt is achieved in a pair of cation-exchange membranes with the efficiency of separation being higher without an electric field. The highest efficiency was attained with Russian-made membranes (MK-40, OOO OKhK "Shchekinoazot"). A full scale experiment on recycling of highly-mineralized blowdown water from the evaporating water treatment system at the Kazan cogeneration power station No. 3 (TETs-3) was performed in a pilot unit consisting of two electromembrane apparatuses made by UAB "Membraninės Technologijos LT". In the experiments every ton of blowdown water yielded 0.1 t of concentrated alkaline solution with an alkali content of up to 4 wt % and 0.9 t of the softened salt solution suitable for the reuse in the TPS cycle. The power rate is 6 kWh / ton of blowdown water.

Effect of Polymer Electrode Morphology on Performance of a Lithium/Polypyrrole Battery. M.S. Thesis

NASA Technical Reports Server (NTRS)

Nicholson, Marjorie Anne

1991-01-01

A variety of conducting polymer batteries were described in the recent literature. In this work, a Li/Polypyrrole secondary battery is described. The effect of controlling the morphology of the polymer on enhancement of counterion diffusion in the polymer phase is explored. A method of preparing conducting polymers was developed which yields high surface area per unit volume of electrode material. A porous membrane is used as a template in which to electrochemically polymerize pyrrole, then the membrane is dissolved, leaving the polymer in a fibrillar form. Conventionally, the polymer is electrochemically polymerized as a dense polymer film on a smooth Pt disk electrode. Previous work has shown that when the polymer is electrochemically polymerized in fribrillar form, charge transport rates are faster and charge capacities are greater than for dense, conventionally grown films containing the same amount of polymer. The purpose is to expand previous work by further investigating the possibilities of the optimization of transport rates in polypyrrole films by controlling the morphology of the films. The utility of fibrillar polypyrrole as a cathode material in a lithium/polymer secondary battery is then assessed. The performance of the fibrillar battery is compared to the performance of an analogous battery which employed a conventionally grown polypyrrole film. The study includes a comparison of cyclic voltammetry, shape of charge/discharge curves, discharge time and voltage, cycle life, coulombic efficiencies, charge capacities, energy densities, and energy efficiencies.

Plasma membranes modified by plasma treatment or deposition as solid electrolytes for potential application in solid alkaline fuel cells.

PubMed

Reinholdt, Marc; Ilie, Alina; Roualdès, Stéphanie; Frugier, Jérémy; Schieda, Mauricio; Coutanceau, Christophe; Martemianov, Serguei; Flaud, Valérie; Beche, Eric; Durand, Jean

2012-07-30

In the highly competitive market of fuel cells, solid alkaline fuel cells using liquid fuel (such as cheap, non-toxic and non-valorized glycerol) and not requiring noble metal as catalyst seem quite promising. One of the main hurdles for emergence of such a technology is the development of a hydroxide-conducting membrane characterized by both high conductivity and low fuel permeability. Plasma treatments can enable to positively tune the main fuel cell membrane requirements. In this work, commercial ADP-Morgane® fluorinated polymer membranes and a new brand of cross-linked poly(aryl-ether) polymer membranes, named AMELI-32®, both containing quaternary ammonium functionalities, have been modified by argon plasma treatment or triallylamine-based plasma deposit. Under the concomitant etching/cross-linking/oxidation effects inherent to the plasma modification, transport properties (ionic exchange capacity, water uptake, ionic conductivity and fuel retention) of membranes have been improved. Consequently, using plasma modified ADP-Morgane® membrane as electrolyte in a solid alkaline fuel cell operating with glycerol as fuel has allowed increasing the maximum power density by a factor 3 when compared to the untreated membrane.

Plasma Membranes Modified by Plasma Treatment or Deposition as Solid Electrolytes for Potential Application in Solid Alkaline Fuel Cells

PubMed Central

Reinholdt, Marc; Ilie, Alina; Roualdès, Stéphanie; Frugier, Jérémy; Schieda, Mauricio; Coutanceau, Christophe; Martemianov, Serguei; Flaud, Valérie; Beche, Eric; Durand, Jean

2012-01-01

In the highly competitive market of fuel cells, solid alkaline fuel cells using liquid fuel (such as cheap, non-toxic and non-valorized glycerol) and not requiring noble metal as catalyst seem quite promising. One of the main hurdles for emergence of such a technology is the development of a hydroxide-conducting membrane characterized by both high conductivity and low fuel permeability. Plasma treatments can enable to positively tune the main fuel cell membrane requirements. In this work, commercial ADP-Morgane® fluorinated polymer membranes and a new brand of cross-linked poly(aryl-ether) polymer membranes, named AMELI-32®, both containing quaternary ammonium functionalities, have been modified by argon plasma treatment or triallylamine-based plasma deposit. Under the concomitant etching/cross-linking/oxidation effects inherent to the plasma modification, transport properties (ionic exchange capacity, water uptake, ionic conductivity and fuel retention) of membranes have been improved. Consequently, using plasma modified ADP-Morgane® membrane as electrolyte in a solid alkaline fuel cell operating with glycerol as fuel has allowed increasing the maximum power density by a factor 3 when compared to the untreated membrane. PMID:24958295

Stepwise heating in Stille polycondensation toward no batch-to-batch variations in polymer solar cell performance.

PubMed

Lee, Sang Myeon; Park, Kwang Hyun; Jung, Seungon; Park, Hyesung; Yang, Changduk

2018-05-14

For a given π-conjugated polymer, the batch-to-batch variations in molecular weight (M w ) and polydispersity index (Ð) can lead to inconsistent process-dependent material properties and consequent performance variations in the device application. Using a stepwise-heating protocol in the Stille polycondensation in conjunction with optimized processing, we obtained an ultrahigh-quality PTB7 polymer having high M w and very narrow Ð. The resulting ultrahigh-quality polymer-based solar cells demonstrate up to 9.97% power conversion efficiencies (PCEs), which is over 24% enhancement from the control devices fabricated with commercially available PTB7. Moreover, we observe almost negligible batch-to-batch variations in the overall PCE values from ultrahigh-quality polymer-based devices. The proposed stepwise polymerization demonstrates a facile and effective strategy for synthesizing high-quality semiconducting polymers that can significantly improve device yield in polymer-based solar cells, an important factor for the commercialization of organic solar cells, by mitigating device-to-device variations.

Preparation of a collagen/polymer hybrid gel designed for tissue membranes. Part I: controlling the polymer-collagen cross-linking process using an ethanol/water co-solvent.

PubMed

Nam, Kwangwoo; Kimura, Tsuyoshi; Funamoto, Seiichi; Kishida, Akio

2010-02-01

The drawback with collagen/2-methacryloyloxyethyl phosphorylcholine (MPC) polymer hybrid gels (collagen/phospholipid polymer hybrid gels) prepared in alkaline morpholinoethane sulfonic acid (MES) aqueous solution is that the cross-linking rate between the polymer and the collagen is low. To solve this problem, ethanol has been adopted as the reaction solvent, to prevent 1-ethyl-3-(3-dimethylaminopropyl)-1-carbodiimide hydrochloride (EDC) hydrolysis. Alterations in the ethanol mole concentration changed the cross-linking rate between the MPC polymer and the collagen gel. Prevention of EDC hydrolysis is clearly observed; protonation of carboxyl groups implies that the ratio of ethanol to water should be controlled. The polymer shows signs of penetration into the collagen gel layer, thus forming a totally homogeneous phase gel. This affects the mechanical strength of the collagen gel, making the gel much stiffer and brittle with an increase in the swelling ratio, as compared with that prepared in MES buffer. However, it is possible to obtain a collagen/phospholipid polymer hybrid gel with a high polymer portion and the cross-linking rate can be successfully controlled.

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.

Molecular engineered conjugated polymer with high thermal conductivity

PubMed Central

Song, Bai; Lee, Elizabeth M. Y.; Gleason, Karen K.

2018-01-01

Traditional polymers are both electrically and thermally insulating. The development of electrically conductive polymers has led to novel applications such as flexible displays, solar cells, and wearable biosensors. As in the case of electrically conductive polymers, the development of polymers with high thermal conductivity would open up a range of applications in next-generation electronic, optoelectronic, and energy devices. Current research has so far been limited to engineering polymers either by strong intramolecular interactions, which enable efficient phonon transport along the polymer chains, or by strong intermolecular interactions, which enable efficient phonon transport between the polymer chains. However, it has not been possible until now to engineer both interactions simultaneously. We report the first realization of high thermal conductivity in the thin film of a conjugated polymer, poly(3-hexylthiophene), via bottom-up oxidative chemical vapor deposition (oCVD), taking advantage of both strong C=C covalent bonding along the extended polymer chain and strong π-π stacking noncovalent interactions between chains. We confirm the presence of both types of interactions by systematic structural characterization, achieving a near–room temperature thermal conductivity of 2.2 W/m·K, which is 10 times higher than that of conventional polymers. With the solvent-free oCVD technique, it is now possible to grow polymer films conformally on a variety of substrates as lightweight, flexible heat conductors that are also electrically insulating and resistant to corrosion. PMID:29670943

Poly(arylene)-based anion exchange polymer electrolytes

DOEpatents

Kim, Yu Seung; Bae, Chulsung

2015-06-09

Poly(arylene) electrolytes including copolymers lacking ether groups in the polymer may be used as membranes and binders for electrocatalysts in preparation of anodes for electrochemical cells such as solid alkaline fuel cells.

Towards high conductivity in anion-exchange membranes for alkaline fuel cells.

PubMed

Li, Nanwen; Guiver, Michael D; Binder, Wolfgang H

2013-08-01

Quaternized poly(2,6-dimethylphenylene oxide) materials (PPOs) containing clicked 1,2,3-triazoles were first prepared through Cu(I) -catalyzed "click chemistry" to improve the anion transport in anion-exchange membranes (AEMs). Clicked 1,2,3-triazoles incorporated into AEMs provided more sites to form efficient and continuous hydrogen-bond networks between the water/hydroxide and the triazole for anion transport. Higher water uptake was observed for these triazole membranes. Thus, the membranes showed an impressive enhancement of the hydroxide diffusion coefficient and, therefore, the anion conductivities. The recorded hydroxide conductivity was 27.8-62 mS cm(-1) at 20 °C in water, which was several times higher than that of a typical PPO-based AEM (TMA-20) derived from trimethylamine (5 mS cm(-1) ). Even at reduced relative humidity, the clicked membrane showed superior conductivity to a trimethylamine-based membrane. Moreover, similar alkaline stabilities at 80 °C in 1 M NaOH were observed for the clicked and non-clicked membranes. The performance of a H2 /O2 single cell assembled with a clicked AEM was much improved compared to that of a non-clicked TMA-20 membrane. The peak power density achieved for an alkaline fuel cell with the synthesized membrane 1a(20) was 188.7 mW cm(-2) at 50 °C. These results indicated that clicked AEM could be a viable strategy for improving the performance of alkaline fuel cells. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Self-Healing Polymer Dielectric for a High Capacitance Gate Insulator.

PubMed

Ko, Jieun; Kim, Young-Jae; Kim, Youn Sang

2016-09-14

Self-healing materials are required for development of various flexible electronic devices to repair cracks and ruptures caused by repetitive bending or folding. Specifically, a self-healing dielectric layer has huge potential to achieve healing electronics without mechanical breakdown in flexible operations. Here, we developed a high performance self-healing dielectric layer with an ionic liquid and catechol-functionalized polymer which exhibited a self-healing ability for both bulk and film states under mild self-healing conditions at 55 °C for 30 min. Due to the sufficient ion mobility of the ionic liquid in the polymer matrix, it had a high capacitance value above 1 μF/cm(2) at 20 Hz. Moreover, zinc oxide (ZnO) thin-film transistors (TFTs) with a self-healing dielectric layer exhibited a high field-effect mobility of 16.1 ± 3.07 cm(2) V(-1) s(-1) at a gate bias of 3 V. Even after repetitive self-healing of the dielectric layer from mechanical breaking, the electrical performance of the TFTs was well-maintained.

Performance of alkaline battery cells used in emergency locator transmitters

NASA Technical Reports Server (NTRS)

Haynes, G. A.; Sokol, S.; Motley, W. R., III; Mcclelland, E. L.

1984-01-01

The characteristics of battery power supplies for emergency locator transmitters (ELT's) were investigated by testing alkaline zinc/manganese dioxide cells of the type typically used in ELT's. Cells from four manufacturers were tested. The cells were subjected to simulated environmental and load conditions representative of those required for survival and operation. Battery cell characteristics that may contribute to ELT malfunctions and limitations were evaluated. Experimental results from the battery cell study are discussed, and an evaluation of ELT performance while operating under a representative worst-case environmental condition is presented.

High-Performance Polymer Solar Cells Based on a Wide-Bandgap Polymer Containing Pyrrolo[3,4-f]benzotriazole-5,7-dione with a Power Conversion Efficiency of 8.63.

PubMed

Lan, Liuyuan; Chen, Zhiming; Hu, Qin; Ying, Lei; Zhu, Rui; Liu, Feng; Russell, Thomas P; Huang, Fei; Cao, Yong

2016-09-01

A novel donor-acceptor type conjugated polymer based on a building block of 4,8-di(thien-2-yl) - 6-octyl-2-octyl-5 H- pyrrolo[3,4- f ]benzotriazole-5,7(6 H )-dione (TZBI) as the acceptor unit and 4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)-benzo-[1,2- b :4,5- b' ]dithiophene as the donor unit, named as PTZBIBDT, is developed and used as an electron-donating material in bulk-heterojunction polymer solar cells. The resulting copolymer exhibits a wide bandgap of 1.81 eV along with relatively deep highest occupied molecular orbital energy level of -5.34 eV. Based on the optimized processing conditions, including thermal annealing, and the use of a water/alcohol cathode interlayer, the single-junction polymer solar cell based on PTZBIBDT:PC 71 BM ([6,6]-phenyl-C 71 -butyric acid methyl ester) blend film affords a power conversion efficiency of 8.63% with an open-circuit voltage of 0.87 V, a short circuit current of 13.50 mA cm -2 , and a fill factor of 73.95%, which is among the highest values reported for wide-bandgap polymers-based single-junction organic solar cells. The morphology studies on the PTZBIBDT:PC 71 BM blend film indicate that a fibrillar network can be formed and the extent of phase separation can be mani-pulated by thermal annealing. These results indicate that the TZBI unit is a very promising building block for the synthesis of wide-bandgap polymers for high-performance single-junction and tandem (or multijunction) organic solar cells.

Cellulose nanocrystal-based composite electrolyte with superior dimensional stability for alkaline fuel cell membranes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, Yuan; Artmentrout, Aaron A.; Li, Juchuan

2015-05-13

Cellulose nanocrystal (CNC)-based composite films were prepared as a solid electrolyte for alkaline fuel cells. Poly (vinyl alcohol) (PVA) and silica gel hybrid was used to bind the CNCs to form a robust composite film. The mass ratio (i.e., 1 : 1, 1 : 2) of PVA and silica gel was tuned to control the hydrophobicity of the resulting films. Composite films with a range of CNC content (i.e., 20 to 60%) were prepared to demonstrate the impact of CNC on the performance of these materials as a solid electrolyte for alkaline fuel cells. Different from previously reported cross-linked polymermore » films, CNC-based composite films with 40% hydrophobic binder (i.e., PVA : silica gel=1 : 2) exhibited simultaneous low water swelling (e.g., ~5%) and high water uptake (e.g., ~80%) due to the hydrophilicity and extraordinary dimensional stability of CNC. It also showed a conductivity of 0.044 and 0.065 S/cm at 20 and 60 oC, respectively. To the best of our knowledge, the film with 60% CNC and 40% binder is characterized by the lowest hydroxide conductivity-normalized swelling ratio. Decreased CNC content (i.e., 40 and 20%) resulted in comparable hydroxide conductivity but a greater swelling ratio. Finally, these results demonstrate the advantage of CNC as a key component for a solid electrolyte for alkaline fuel cells over conventional polymers, suggesting the great potential of CNCs in improving the dimensional stability while maintaining the conductivity of existing anion exchange membranes.« less

Highly conductive and flexible nano-structured carbon-based polymer nanocomposites with improved electromagnetic-interference-shielding performance

NASA Astrophysics Data System (ADS)

Mondal, Subhadip; Ghosh, Sabyasachi; Ganguly, Sayan; Das, Poushali; Ravindren, Revathy; Sit, Subhashis; Chakraborty, Goutam; Das, Narayan Ch

2017-10-01

Widespread usage and development of electrical/electronic devices can create severe problems for various other devices and in our everyday lives due to harmful exposure to electromagnetic (EM) radiation. Herein, we report on the electromagnetic interference (EMI)-shielding performance of highly flexible and conductive chlorinated polyethylene (CPE)/carbon nanofiber (CNF) nanocomposites fabricated by a probe-sonication-assisted simple solution-mixing process. The dispersion of CNF nanofillers inside the CPE matrix has been studied by electron micrographs. This dispersion is reflected in the formation of continuous conductive networks at a low percolation-threshold value of 2.87 wt% and promising EMI-shielding performance of 41.5 dB for 25 wt% CNF in the X-band frequency (8.2-12.4 GHz). Such an intriguing performance mainly depends on the unique filler-filler or filler-polymer networks in CPE nanocomposites. In addition, the composite material displays a superior EMI efficiency of 47.5 dB for 2.0 mm thickness at 8.2 GHz. However, we have been encouraged by the promotion of highly flexible and lightweight CPE/CNF nanocomposite as a superior EMI shield, which can protect electronic devices against harm caused by EM radiation and offers an adaptable solution in advanced EMI-shield applications.

High thermal conductivity in electrostatically engineered amorphous polymers

PubMed Central

Shanker, Apoorv; Li, Chen; Kim, Gun-Ho; Gidley, David; Pipe, Kevin P.; Kim, Jinsang

2017-01-01

High thermal conductivity is critical for many applications of polymers (for example, packaging of light-emitting diodes), in which heat must be dissipated efficiently to maintain the functionality and reliability of a system. Whereas uniaxially extended chain morphology has been shown to significantly enhance thermal conductivity in individual polymer chains and fibers, bulk polymers with coiled and entangled chains have low thermal conductivities (0.1 to 0.4 W m−1 K−1). We demonstrate that systematic ionization of a weak anionic polyelectrolyte, polyacrylic acid (PAA), resulting in extended and stiffened polymer chains with superior packing, can significantly enhance its thermal conductivity. Cross-plane thermal conductivity in spin-cast amorphous films steadily grows with PAA degree of ionization, reaching up to ~1.2 W m−1 K−1, which is on par with that of glass and about six times higher than that of most amorphous polymers, suggesting a new unexplored molecular engineering strategy to achieve high thermal conductivities in amorphous bulk polymers. PMID:28782022

Asymmetric membranes for destabilization of oil droplets in produced water from alkaline-surfactant-polymer (ASP) flooding

NASA Astrophysics Data System (ADS)

Ramlee, Azierah; Chiam, Chel-Ken; Sarbatly, Rosalam

2018-05-01

This work presents a study of destabilization of oil droplets in the produced water from alkaline-surfactant-polymer (ASP) flooding by using four types of laboratory-fabricated polyvinylidene fluoride (PVDF) membranes. The PVDF membranes were fabricated via immersion precipitation method with ethanol (0 - 30 %, v/v) as the coagulant. The membranes with the effective area of 17.35 cm2 were tested with synthesized ASP solution as the feed in cross-flow microfiltration process. The ASP feed solution initially contained the oil droplets with radius ranged from 40 to 100 nm and the mean radius was 61 nm. Results have shown that the concentration of the ethanol in the coagulation bath affects the formation of the membrane structure and the corresponding porosity, while no significance influence on the membrane thickness. Coalescence of the oil droplets was occurred when the ASP solution permeated through the asymmetric PVDF membranes. Through the coalescence process, the oil droplets were destabilized where the radius of the oil droplets in the permeates increased to 1.5-4 µm with the corresponding mean radius ranged from 2.4 to 2.7 µm.

Enhanced Performance of Recycled Aggregate Concrete with Atomic Polymer Technology

DOT National Transportation Integrated Search

2012-06-01

The atomic polymer technology in form of mesoporous inorganic polymer (MIP) can effectively improve material durability and performance of concrete by dramatically increase inter/intragranular bond strength of concrete at nano-scale. The strategy of ...

Exploring Alkaline Stable Organic Cations for Polymer Hydroxide Exchange Membranes

DTIC Science & Technology

2015-04-29

1   1.1.2   Proton exchange membrane fuel cells ( PEMFCs ) ......................... 3   1.1.3   Alkaline fuel cells (AFCs...160   xi LIST OF FIGURES Figure 1.1:   Schematic diagram of a PEMFC ...according to the type of electrolyte they use. Nowadays, there are six major types of fuel cells: proton-exchange membrane fuel cells ( PEMFCs ), hydroxide

Understanding charge transport and recombination losses in high performance polymer solar cells with non-fullerene acceptors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Xuning; Zuo, Xiaobing; Xie, Shenkun

Photovoltaic characteristics, recombination and charge transport properties are investigated. The determined recombination reduction factor can reconcile the supreme device performance in organic solar cells using non-fullerene ITIC acceptor and severe carrier losses in all-polymer devices with P(NDI2OD-T2).

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

Shedding light on the paradox of high alkaline phosphatase utilization at high end-product concentrations

NASA Astrophysics Data System (ADS)

Baltar, F.; Lundin, D.; Palovaara, J.; Reinthaler, T.; Herndl, G. J.; Pinhassi, J.

2016-02-01

Alkaline phosphatase (APase) activity is supposed to be regulated by the concentration of its endproduct, decreasing with increasing inorganic phosphate (Pi) concentrations. Since Pi is readily available in the deep ocean, APase activity would be expected to be low. However, high APase activities at high Pi concentrations have been found in the deep Indian and Atlantic Ocean. To understand how APase activities are regulated and what mechanisms are responsible for its regulation we performed microcosm experiments with mesopelagic North Atlantic waters. Treatments consisted of enrichment with either ammonium or organic carbon, and were compared to unamended controls. We assessed changes in prokaryotic abundance, APase, leucine aminopeptidase, heterotrophic production, dark CO2 fixation and community gene expression (metatranscriptomics) between treatments and control. In the organic matter enrichments, APase increased along with all measured rates, whereas only dark CO2 fixation and APase were enhanced in the ammonium enrichment. In the organic matter enrichment, genes for heterotrophic metabolism were strongly upregulated, whereas genes for ammonia oxidation and CO2 fixation were upregulated in the ammonium treatment. In both treatments, the Pho regulon -a global regulatory mechanism involved in bacterial Pi management- was also upregulated, including genes encoding alkaline phosphatases. The activation of the Pho regulon seemed to be related to cross-activation by nonpartner histidine kinases, and/or the activation of genes involved in the regulation of elemental balance during catabolic processes. Increased C or N bioavailability thus appear to elicit a Pi deficiency inside cells and activate the Pho regulon. These results indicate possible ways (e.g. pulses of C or N or changes in elemental ratios) in which APase can be activated irrespectively of the environmental Pi concentration.

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.

High-performance supercapacitors of Cu-based porous coordination polymer nanowires and the derived porous CuO nanotubes.

PubMed

Wu, Meng-Ke; Zhou, Jiao-Jiao; Yi, Fei-Yan; Chen, Chen; Li, Yan-Li; Li, Qin; Tao, Kai; Han, Lei

2017-12-12

Electrode materials for supercapacitors with one-dimensional porous nanostructures, such as nanowires and nanotubes, are very attractive for high-efficiency storage of electrochemical energy. Herein, ultralong Cu-based porous coordination polymer nanowires (copper-l-aspartic acid) were used as the electrode material for supercapacitors, for the first time. The as-prepared material exhibits a high specific capacitance of 367 F g -1 at 0.6 A g -1 and excellent cycling stability (94% retention over 1000 cycles). Moreover, porous CuO nanotubes were successfully fabricated by the thermal decomposition of this nanowire precursor. The CuO nanotube exhibits good electrochemical performance with high rate capacity (77% retention at 12.5 A g -1 ) and long-term stability (96% retention over 1000 cycles). The strategy developed here for the synthesis of porous nanowires and nanotubes can be extended to the construction of other electrode materials for more efficient energy storage.

Metal-Organic Coordination Polymer to Prepare Density Controllable and High Nitrogen-Doped Content Carbon/Graphene for High Performance Supercapacitors.

PubMed

Luo, Jinwei; Zhong, Wenbin; Zou, Yubo; Xiong, Changlun; Yang, Wantai

2017-01-11

Design and preparation of carbon-based electrode material with high nitrogen-doping ratio and appropriate density attract much interest for supercapacitors in practical application. Herein, three porous carbon/graphene (NCG Cu , NCG Fe , and NCG Zn ) with high doping ratio of nitrogen have been prepared via directly pyrolysis of graphene oxide (GO)/metal-organic coordination polymer (MOCP) composites, which were formed by reacting 4,4'-bipyridine (BPD) with CuCl 2 , FeCl 3 , and ZnCl 2 , respectively. As-prepared NCG Cu , NCG Fe and NCG Zn showed high nitrogen doping ratio of 10.68, 12.99, and 11.21 at. %; and high density of 1.52, 0.84, and 1.15 g cm -3 , respectively. When as-prepared samples were used as supercapacitor electrodes, NCG Cu , NCG Fe and NCG Zn exhibited high gravimetric specific capacitances of 369, 298.5, 309.5 F g -1 , corresponding to high volumetric specific capacitances of 560.9, 250.7, 355.9 F cm -3 at a current density of 0.5 A g -1 , as well as good cycling stability, nearly 100% of the capacitance retained after 1000 cycles even at a large current density of 10 A g -1 . It is expected that the provided novel strategy can be used to develop electrode materials in high performance energy conversion/storage devices.

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.

Behavior of polymer cladding materials under extremely high temperatures

NASA Astrophysics Data System (ADS)

Clark, Timothy E.; Chang, Selee; Kwak, SeungJo; Oh, Jung Hyun

2012-01-01

Polymer claddings with low refractive indices for silica core fibers were developed. Applications include fiber lasers and transmission of high power lasers in surgery. For many applications, operating fibers under high temperatures is desirable. In a previous publication, the results of testing polymer cladded silica core fiber at 150°C for 6400 hours were given, along with 5000 hours of testing polymer films. The results at 150°C were encouraging, with little additional loss measured. Here we test polymers under more severe conditions, at 270°C, for periods up to 10 hours. The polymers' cured indices range from 1.374 to 1.397 (at 852 nm). Changes in Young's modulus, refractive index, yellowing, weight, hardness, strength, and elongation were observed. While these polymers cannot function at 270°C for extended periods, it is possible to expose them for shorter durations without significant damage. Some polymer properties actually improved after 4 hours of heating. Fibers clad with such polymers have been successfully jacketed with extruded materials, and have endured high temperatures for a few minutes. It is possible that a sensor, fiber laser or other fiber device could function in these temperatures for short periods without the coating properties changing beyond values required for operation.

Proton-conducting membranes based on benzimidazole polymers for high-temperature PEM fuel cells. A chemical quest.

PubMed

Asensio, Juan Antonio; Sánchez, Eduardo M; Gómez-Romero, Pedro

2010-08-01

The development of high-temperature PEM fuel cells (working at 150-200 degrees C) is pursued worldwide in order to solve some of the problems of current cells based on Nafion (CO tolerance, improved kinetics, water management, etc.). Polybenzimidazole membranes nanoimpregnated with phosphoric acid have been studied as electrolytes in PEMFCs for more than a decade. Commercially available polybenzimidazole (PBI) has been the most extensively studied and used for this application in membranes doped with all sorts of strong inorganic acids. In addition to this well-known polymer we also review here studies on ABPBI and other polybenzimidazole type membranes. More recently, several copolymers and related derivatives have attracted many researchers' attention, adding variety to the field. Furthermore, besides phosphoric acid, many other strong inorganic acids, as well as alkaline electrolytes have been used to impregnate benzimidazole membranes and are analyzed here. Finally, we also review different hybrid materials based on polybenzimidazoles and several inorganic proton conductors such as heteropoly acids, as well as sulfonated derivatives of the polymers, all of which contribute to a quickly-developing field with many blooming results and useful potential which are the subject of this critical review (317 references).

Specific Consideration on Superior Performance and Evaluation Methods of Polymer-housed Surge Arresters

NASA Astrophysics Data System (ADS)

Ishizaki, Yoshihiro; Kobayashi, Misao; Suzuki, Hironori; Futagami, Koichi

It is very suitable to select the polymer materials for the housings of surge arresters (SAs), because the polymer materials are generally soft and light weight. Therefore, many kinds of polymer-housed SAs using various polymer materials have been developed, and expanding into many countries. Considering these backgrounds, the JEC technical report (JEC-TR) 23002-2008; polymer-housed surge arrester(1) has been established based on the existent relevant standards of arresters, such as JEC-2371-2003; Insulator-housed surge arresters(2) and IEC 60099-4 Edition 2.2, Metal-oxide surge arresters (MOSAs) without gaps for a.c. systems(3) in order to introduce the technology and provide a common guide for testing of polymer-housed SAs. According as the JEC-TR, the various new applications of the polymer-housed SAs, which are caused by superior advantages such as compact, light weight, safe failure mode, anti-seismic performance, anti-pollution performance and cost efficiency design, have been realized recently in Japan. Therefore, this paper gives specific consideration on the superior performance of the polymer-housed SAs and the evaluation methods of the polymer-housed SAs, because there are some issues in the existent standards to be solved.

High performance nano-Ni/Graphite electrode for electro-oxidation in direct alkaline ethanol fuel cells

NASA Astrophysics Data System (ADS)

Soliman, Ahmed B.; Abdel-Samad, Hesham S.; Abdel Rehim, Sayed S.; Ahmed, Mohamed A.; Hassan, Hamdy H.

2016-09-01

Ni/Graphite electrocatalysts (Ni/G) are successfully prepared through electrodeposition of Ni from acidic (pH = 0.8) and feebly acidic (pH = 5.5) aqueous Ni (II) baths. The efficiencies of such electrodes are investigated as anodes for direct alkaline ethanol fuel cells through their ethanol electrooxidation cyclic voltammetric (CV) response in alkaline medium. A direct proportionality between the amount of the electrodeposited Ni and its CV response is found. The amounts of the deposited Ni from the two baths are recorded using the Electrochemical Quartz Crystal Microbalance (eQCM). The Ni/G electrodes prepared from the feebly acidic bath show a higher electrocatalytic response than those prepared from the acidic bath. Surface morphology of the Ni particles electrodeposited from feebly acidic bath appears in a nano-scale dimension. Various electrochemical experiments are conducted to confirm that the Ni/G ethanol electrooxidation CV response greatly depends on the pH rather than nickel ion concentration of the deposition bath. The eQCM technique is used to detect the crystalline phases of nickel as α-Ni(OH)2/γ-NiOOH and β-Ni(OH)2/β-NiOOH and their in-situ inter-transformations during the potentiodynamic polarization.

Ultra-high polarity ceramics induced extrinsic high permittivity of polymers contributing to high permittivity of 2-2 series composites

NASA Astrophysics Data System (ADS)

Feng, Yefeng; Zhang, Jianxiong; Hu, Jianbing; Peng, Cheng; He, Renqi

2018-01-01

Induced polarization at interface has been confirmed to have significant impact on the dielectric properties of 2-2 series composites bearing Si-based semi-conductor sheet and polymer layer. By compositing, the significantly elevated high permittivity in Si-based semi-conductor sheet should be responsible for the obtained high permittivity in composites. In that case, interface interaction could include two aspects namely a strong electrostatic force from high polarity polymeric layer and a newborn high polarity induced in Si-based ceramic sheet. In this work, this class of interface induced polarization was successfully extended into another 2-2 series composite system made up of ultra-high polarity ceramic sheet and high polarity polymer layer. By compositing, the greatly improved high permittivity in high polarity polymer layer was confirmed to strongly contribute to the high permittivity achieved in composites. In this case, interface interaction should consist of a rather large electrostatic force from ultra-high polarity ceramic sheet with ionic crystal structure and an enhanced high polarity induced in polymer layer based on a large polarizability of high polarity covalent dipoles in polymer. The dielectric and conductive properties of four designed 2-2 series composites and their components have been detailedly investigated. Increasing of polymer inborn polarity would lead to a significant elevating of polymer overall polarity in composite. Decline of inherent polarities in two components would result in a mild improving of polymer total polarity in composite. Introducing of non-polarity polymeric layer would give rise to a hardly unaltered polymer overall polarity in composite. The best 2-2 composite could possess a permittivity of ˜463 at 100 Hz 25.7 times of the original permittivity of polymer in it. This work might offer a facile route for achieving the promising composite dielectrics by constructing the 2-2 series samples from two high polarity

Separator Materials Used in Secondary Alkaline Batteries Characterized and Evaluated

NASA Technical Reports Server (NTRS)

1996-01-01

Nickel-cadmium (Ni/Cd) and nickel-hydrogen (Ni/H2) secondary alkaline batteries are vital to aerospace applications. Battery performance and cycle life are significantly affected by the type of separators used in those batteries. A team from NASA Lewis Research Center's Electrochemical Technology Branch developed standardized testing procedures to characterize and evaluate new and existing separator materials to improve performance and cycle life of secondary alkaline batteries. Battery separators must function as good electronic insulators and as efficient electrolyte reservoirs. At present, new types of organic and inorganic separator materials are being developed for Ni/Cd and Ni/H2 batteries. The separator material previously used in the NASA standard Ni/Cd was Pellon 2505, a 100-percent nylon-6 polymer that must be treated with zinc chloride (ZnCl2) to bond the fibers. Because of stricter Environmental Protection Agency regulation of ZnCl2 emissions, the battery community has been searching for new separators to replace Pellon 2505. As of today, two candidate separator materials have been identified; however, neither of the two materials have performed as well as Pellon 2505. The separator test procedures that were devised at Lewis are being implemented to expedite the search for new battery separators. The new test procedures, which are being carried out in the Separator Laboratory at Lewis, have been designed to guarantee accurate evaluations of the properties that are critical for sustaining proper battery operation. These properties include physical and chemical stability, chemical purity, gas permeability, electrolyte retention and distribution, uniformity, porosity, and area resistivity. A manual containing a detailed description of 12 separator test procedures has been drafted and will be used by the battery community to evaluate candidate separator materials for specific applications. These standardized procedures will allow for consistent, uniform

High-performance fiber/epoxy composite pressure vessels

NASA Technical Reports Server (NTRS)

Chiao, T. T.; Hamstad, M. A.; Jessop, E. S.; Toland, R. H.

1978-01-01

Activities described include: (1) determining the applicability of an ultrahigh-strength graphite fiber to composite pressure vessels; (2) defining the fatigue performance of thin-titanium-lined, high-strength graphite/epoxy pressure vessel; (3) selecting epoxy resin systems suitable for filament winding; (4) studying the fatigue life potential of Kevlar 49/epoxy pressure vessels; and (5) developing polymer liners for composite pressure vessels. Kevlar 49/epoxy and graphite fiber/epoxy pressure vessels, 10.2 cm in diameter, some with aluminum liners and some with alternation layers of rubber and polymer were fabricated. To determine liner performance, vessels were subjected to gas permeation tests, fatigue cycling, and burst tests, measuring composite performance, fatigue life, and leak rates. Both the metal and the rubber/polymer liner performed well. Proportionately larger pressure vessels (20.3 and 38 cm in diameter) were made and subjected to the same tests. In these larger vessels, line leakage problems with both liners developed the causes of the leaks were identified and some solutions to such liner problems are recommended.

Evolution of sequence-defined highly functionalized nucleic acid polymers

NASA Astrophysics Data System (ADS)

Chen, Zhen; Lichtor, Phillip A.; Berliner, Adrian P.; Chen, Jonathan C.; Liu, David R.

2018-03-01

The evolution of sequence-defined synthetic polymers made of building blocks beyond those compatible with polymerase enzymes or the ribosome has the potential to generate new classes of receptors, catalysts and materials. Here we describe a ligase-mediated DNA-templated polymerization and in vitro selection system to evolve highly functionalized nucleic acid polymers (HFNAPs) made from 32 building blocks that contain eight chemically diverse side chains on a DNA backbone. Through iterated cycles of polymer translation, selection and reverse translation, we discovered HFNAPs that bind proprotein convertase subtilisin/kexin type 9 (PCSK9) and interleukin-6, two protein targets implicated in human diseases. Mutation and reselection of an active PCSK9-binding polymer yielded evolved polymers with high affinity (KD = 3 nM). This evolved polymer potently inhibited the binding between PCSK9 and the low-density lipoprotein receptor. Structure-activity relationship studies revealed that specific side chains at defined positions in the polymers are required for binding to their respective targets. Our findings expand the chemical space of evolvable polymers to include densely functionalized nucleic acids with diverse, researcher-defined chemical repertoires.

Comparison of enteral and parenteral methods of urine alkalinization in patients receiving high-dose methotrexate.

PubMed

Rouch, Jamie A; Burton, Bradley; Dabb, Alix; Brown, Vicky; Seung, Amy H; Kinsman, Katharine; Holdhoff, Matthias

2017-01-01

Purpose Hyperhydration and urinary alkalinization is implemented with all high-dose (HD)-methotrexate infusions to promote excretion and prevent precipitation of methotrexate in the renal tubules. Our institution utilized enteral alkalinizing agents (sodium bicarbonate tablets and sodium citrate/citric acid solution) to alkalinize the urine of patients receiving HD-methotrexate during a parenteral sodium bicarbonate and sodium acetate shortage. The purpose of this study is to establish the safety and efficacy of the enteral route for urine alkalinization. Methods A single-center, retrospective, cohort study was conducted comparing cycles of HD-methotrexate using enteral alkalinizing agents to parenteral sodium bicarbonate. The primary objective was to compare the time, in hours, from administration of first inpatient administered dose of alkalinizing agent to time of achieving goal urine pH. Secondary objectives evaluated total dose of sodium bicarbonate required to achieve goal urine pH, time from start of urine alkalinizing agent until time of achieving methotrexate level safe for discharge, and toxicities associated with methotrexate and the alkalinizing agents. Results A total of 118 patients were included in this study, equally divided into two cohorts based on parenteral versus enteral routes of administration. No statistical difference was determined between the two cohorts regarding time to goal urine pH (6.5 h versus 7.9 h, P = 0.051) or regarding time to methotrexate level deemed safe for discharge (63.5 h versus 62.5 h, p = 0.835). There were no significant differences in methotrexate-induced toxicities. Conclusion Our study found enteral routes of urine alkalinization to be a viable alternative to the traditional parenteral sodium bicarbonate, especially during parenteral sodium bicarbonate and acetate shortages.

A Silica-Aerogel-Reinforced Composite Polymer Electrolyte with High Ionic Conductivity and High Modulus.

PubMed

Lin, Dingchang; Yuen, Pak Yan; Liu, Yayuan; Liu, Wei; Liu, Nian; Dauskardt, Reinhold H; Cui, Yi

2018-06-25

High-energy all-solid-state lithium (Li) batteries have great potential as next-generation energy-storage devices. Among all choices of electrolytes, polymer-based systems have attracted widespread attention due to their low density, low cost, and excellent processability. However, they are generally mechanically too weak to effectively suppress Li dendrites and have lower ionic conductivity for reasonable kinetics at ambient temperature. Herein, an ultrastrong reinforced composite polymer electrolyte (CPE) is successfully designed and fabricated by introducing a stiff mesoporous SiO 2 aerogel as the backbone for a polymer-based electrolyte. The interconnected SiO 2 aerogel not only performs as a strong backbone strengthening the whole composite, but also offers large and continuous surfaces for strong anion adsorption, which produces a highly conductive pathway across the composite. As a consequence, a high modulus of ≈0.43 GPa and high ionic conductivity of ≈0.6 mS cm -1 at 30 °C are simultaneously achieved. Furthermore, LiFePO 4 -Li full cells with good cyclability and rate capability at ambient temperature are obtained. Full cells with cathode capacity up to 2.1 mAh cm -2 are also demonstrated. The aerogel-reinforced CPE represents a new design principle for solid-state electrolytes and offers opportunities for future all-solid-state Li batteries. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Correlation of Surface Adsorption and Oxidation with a Floatability Difference of Galena and Pyrite in High-Alkaline Lime Systems.

PubMed

Niu, Xiaopeng; Ruan, Renman; Xia, Liuyin; Li, Li; Sun, Heyun; Jia, Yan; Tan, Qiaoyi

2018-02-27

When it comes to Pb-Zn ores with high amounts of pyrite, the major problem encountered is the low separation efficiency between galena and pyrite. By virtue of high dosage of lime and collector sodium diethyl dithiocarbamate (DDTC), pyrite and zinc minerals are depressed, allowing the galena to be floated. However, there have been significant conflicting reports on the flotation behavior of galena at high pH. In this context, correlation of the surface adsorption and oxidation with the floatability difference of galena and pyrite in high-alkaline lime systems would be a key issue for process optimization. Captive bubble contact angle measurements were performed on freshly polished mineral surfaces in situ exposed to lime solutions of varying pH as a function of immersion time. Furthermore, single mineral microflotation tests were conducted. Both tests indicated that the degree of hydrophobicity on the surfaces of galena and pyrite increased in the presence of DDTC at natural or mild pulp pH. While in a saturated lime solution, at pH 12.5, DDTC only worked for galena, but not for pyrite. Surface chemistry analysis by time-of-flight secondary ion mass spectrometry (Tof-SIMS) confirmed the preference of DDTC on the galena surface at pH 12.5, which contributed to a merit recovery. Further important evidence through measurements of Tof-SIMS, ion chromatography, and high-performance liquid chromatography indicated that in high-alkaline lime systems, the merit floatability of galena could exclude the insignificant contribution of elemental sulfur (S 8 ) and was dominantly attributed by the strong adsorption of DDTC. In contrast, the poor flotation response of pyrite at high pH was due to the prevailing adsorption of CaOH + species. This study provides an important surface chemistry evidence for a better understanding of the mechanism on the better selectivity in the galena-pyrite separation adopting high-alkaline lime systems.

A stable solution-processed polymer semiconductor with record high-mobility for printed transistors

PubMed Central

Li, Jun; Zhao, Yan; Tan, Huei Shuan; Guo, Yunlong; Di, Chong-An; Yu, Gui; Liu, Yunqi; Lin, Ming; Lim, Suo Hon; Zhou, Yuhua; Su, Haibin; Ong, Beng S.

2012-01-01

Microelectronic circuits/arrays produced via high-speed printing instead of traditional photolithographic processes offer an appealing approach to creating the long-sought after, low-cost, large-area flexible electronics. Foremost among critical enablers to propel this paradigm shift in manufacturing is a stable, solution-processable, high-performance semiconductor for printing functionally capable thin-film transistors — fundamental building blocks of microelectronics. We report herein the processing and optimisation of solution-processable polymer semiconductors for thin-film transistors, demonstrating very high field-effect mobility, high on/off ratio, and excellent shelf-life and operating stabilities under ambient conditions. Exceptionally high-gain inverters and functional ring oscillator devices on flexible substrates have been demonstrated. This optimised polymer semiconductor represents a significant progress in semiconductor development, dispelling prevalent skepticism surrounding practical usability of organic semiconductors for high-performance microelectronic devices, opening up application opportunities hitherto functionally or economically inaccessible with silicon technologies, and providing an excellent structural framework for fundamental studies of charge transport in organic systems. PMID:23082244

Naphthodipyrrolidone (NDP) based conjugated polymers with high electron mobility and ambipolar transport properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Haichang; Zhang, Shuo; Mao, Yifan

Two novel donor–acceptor π-conjugated polymers based on naphthodipyrrolidone (NDP) were synthesized and characterized. The polymers possess low band gaps and suitable molecular orbital levels as ambipolar semiconductors. The thin film organic field effect transistor of NDP polymers exhibited ambipolar transport properties with a high electron mobility up to 0.67 cm 2 V –1 s –1. The grazing-incidence wide-angle X-ray scattering (GIWAXS) studies demonstrated that the polymer molecules pack into a long-range-ordered lamellar structure with isotropically oriented crystalline domains. Thermal annealing promoted edge-on lamellar stacking as evidenced by the increased diffraction intensity along the out-of-plane direction. In conclusion, the polymer withmore » NDP and bithiophene units achieved the best edge-on lamellar stacking after thermal annealing, which yielded the best electron transport performance in this work.« less

Naphthodipyrrolidone (NDP) based conjugated polymers with high electron mobility and ambipolar transport properties

DOE PAGES

Zhang, Haichang; Zhang, Shuo; Mao, Yifan; ...

2017-05-12

Two novel donor–acceptor π-conjugated polymers based on naphthodipyrrolidone (NDP) were synthesized and characterized. The polymers possess low band gaps and suitable molecular orbital levels as ambipolar semiconductors. The thin film organic field effect transistor of NDP polymers exhibited ambipolar transport properties with a high electron mobility up to 0.67 cm 2 V –1 s –1. The grazing-incidence wide-angle X-ray scattering (GIWAXS) studies demonstrated that the polymer molecules pack into a long-range-ordered lamellar structure with isotropically oriented crystalline domains. Thermal annealing promoted edge-on lamellar stacking as evidenced by the increased diffraction intensity along the out-of-plane direction. In conclusion, the polymer withmore » NDP and bithiophene units achieved the best edge-on lamellar stacking after thermal annealing, which yielded the best electron transport performance in this work.« less

Prebiotic Synthesis of Glycine from Ethanolamine in Simulated Archean Alkaline Hydrothermal Vents

NASA Astrophysics Data System (ADS)

Zhang, Xianlong; Tian, Ge; Gao, Jing; Han, Mei; Su, Rui; Wang, Yanxiang; Feng, Shouhua

2017-12-01

Submarine hydrothermal vents are generally considered as the likely habitats for the origin and evolution of early life on Earth. In recent years, a novel hydrothermal system in Archean subseafloor has been proposed. In this model, highly alkaline and high temperature hydrothermal fluids were generated in basalt-hosted hydrothermal vents, where H2 and CO2 could be abundantly provided. These extreme conditions could have played an irreplaceable role in the early evolution of life. Nevertheless, sufficient information has not yet been obtained for the abiotic synthesis of amino acids, which are indispensable components of life, at high temperature and alkaline condition. This study aims to propose a new method for the synthesis of glycine in simulated Archean submarine alkaline vent systems. We investigated the formation of glycine from ethanolamine under conditions of high temperature (80-160 °C) and highly alkaline solutions (pH = 9.70). Experiments were performed in an anaerobic environment under mild pressure (0.1-8.0 MPa) at the same time. The results suggested that the formation of glycine from ethanolamine occurred rapidly and efficiently in the presence of metal powders, and was favored by high temperatures and high pressures. The experiment provides a new pathway for prebiotic glycine formation and points out the phenomenal influence of high-temperature alkaline hydrothermal vents in origin of life in the early ocean.

Prebiotic Synthesis of Glycine from Ethanolamine in Simulated Archean Alkaline Hydrothermal Vents.

PubMed

Zhang, Xianlong; Tian, Ge; Gao, Jing; Han, Mei; Su, Rui; Wang, Yanxiang; Feng, Shouhua

2017-12-01

Submarine hydrothermal vents are generally considered as the likely habitats for the origin and evolution of early life on Earth. In recent years, a novel hydrothermal system in Archean subseafloor has been proposed. In this model, highly alkaline and high temperature hydrothermal fluids were generated in basalt-hosted hydrothermal vents, where H 2 and CO 2 could be abundantly provided. These extreme conditions could have played an irreplaceable role in the early evolution of life. Nevertheless, sufficient information has not yet been obtained for the abiotic synthesis of amino acids, which are indispensable components of life, at high temperature and alkaline condition. This study aims to propose a new method for the synthesis of glycine in simulated Archean submarine alkaline vent systems. We investigated the formation of glycine from ethanolamine under conditions of high temperature (80-160 °C) and highly alkaline solutions (pH = 9.70). Experiments were performed in an anaerobic environment under mild pressure (0.1-8.0 MPa) at the same time. The results suggested that the formation of glycine from ethanolamine occurred rapidly and efficiently in the presence of metal powders, and was favored by high temperatures and high pressures. The experiment provides a new pathway for prebiotic glycine formation and points out the phenomenal influence of high-temperature alkaline hydrothermal vents in origin of life in the early ocean.

A two-step strategy to visually identify molecularly imprinted polymers for tagged proteins.

PubMed

Brandis, Alexander; Partouche, Eran; Yechezkel, Tamar; Salitra, Yoseph; Shkoulev, Vladimir; Scherz, Avigdor; Grynszpan, Flavio

2017-08-01

A practical and relatively simple method to identify molecularly imprinted polymers capable of binding proteins via the molecular tagging (epitope-like) approach has been developed. In our two-step method, we first challenge a previously obtained anti-tag molecularly imprinted polymer with a small molecule including the said tag of choice (a biotin derivative as shown here or other) connected to a linker bound to a second biotin moiety. An avidin molecule partially decorated with fluorescent labels is then allowed to bind the available biotin derivative associated with the polymer matrix. At the end of this simple process, and after washing off all the low-affinity binding molecules from the polymer matrix, only suitable molecularly imprinted polymers binding avidin through its previously acquired small molecule tag (or epitope-like probe, in a general case) will remain fluorescent. For confirmation, we tested the selective performance of the anti-biotin molecularly imprinted polymer binding it to biotinylated alkaline phosphatase. Residual chemical activity of the enzyme on the molecularly imprinted polymer solid support was observed. In all cases, the corresponding nonimprinted polymer controls were inactive. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Polymer-Sorted Semiconducting Carbon Nanotube Networks for High-Performance Ambipolar Field-Effect Transistors

PubMed Central

2014-01-01

Efficient selection of semiconducting single-walled carbon nanotubes (SWNTs) from as-grown nanotube samples is crucial for their application as printable and flexible semiconductors in field-effect transistors (FETs). In this study, we use atactic poly(9-dodecyl-9-methyl-fluorene) (a-PF-1-12), a polyfluorene derivative with asymmetric side-chains, for the selective dispersion of semiconducting SWNTs with large diameters (>1 nm) from plasma torch-grown SWNTs. Lowering the molecular weight of the dispersing polymer leads to a significant improvement of selectivity. Combining dense semiconducting SWNT networks deposited from an enriched SWNT dispersion with a polymer/metal-oxide hybrid dielectric enables transistors with balanced ambipolar, contact resistance-corrected mobilities of up to 50 cm2·V–1·s–1, low ohmic contact resistance, steep subthreshold swings (0.12–0.14 V/dec) and high on/off ratios (106) even for short channel lengths (<10 μm). These FETs operate at low voltages (<3 V) and show almost no current hysteresis. The resulting ambipolar complementary-like inverters exhibit gains up to 61. PMID:25493421

Structure-Property Relationships of Semiconducting Polymers for Flexible and Durable Polymer Field-Effect Transistors.

PubMed

Kim, Min Je; Jung, A-Ra; Lee, Myeongjae; Kim, Dongjin; Ro, Suhee; Jin, Seon-Mi; Nguyen, Hieu Dinh; Yang, Jeehye; Lee, Kyung-Koo; Lee, Eunji; Kang, Moon Sung; Kim, Hyunjung; Choi, Jong-Ho; Kim, BongSoo; Cho, Jeong Ho

2017-11-22

We report high-performance top-gate bottom-contact flexible polymer field-effect transistors (FETs) fabricated by flow-coating diketopyrrolopyrrole (DPP)-based and naphthalene diimide (NDI)-based polymers (P(DPP2DT-T2), P(DPP2DT-TT), P(DPP2DT-DTT), P(NDI2OD-T2), P(NDI2OD-F2T2), and P(NDI2OD-Se2)) as semiconducting channel materials. All of the polymers displayed good FET characteristics with on/off current ratios exceeding 10 7 . The highest hole mobility of 1.51 cm 2 V -1 s -1 and the highest electron mobility of 0.85 cm 2 V -1 s -1 were obtained from the P(DPP2DT-T2) and P(NDI2OD-Se2) polymer FETs, respectively. The impacts of the polymer structures on the FET performance are well-explained by the interplay between the crystallinity, the tendency of the polymer backbone to adopt an edge-on orientation, and the interconnectivity of polymer fibrils in the film state. Additionally, we demonstrated that all of the flexible polymer-based FETs were highly resistant to tensile stress, with negligible changes in their carrier mobilities and on/off ratios after a bending test. Conclusively, these high-performance, flexible, and durable FETs demonstrate the potential of semiconducting conjugated polymers for use in flexible electronic applications.

Performance of dielectric nanocomposites: matrix-free, hairy nanoparticle assemblies and amorphous polymer-nanoparticle blends.

PubMed

Grabowski, Christopher A; Koerner, Hilmar; Meth, Jeffrey S; Dang, Alei; Hui, Chin Ming; Matyjaszewski, Krzysztof; Bockstaller, Michael R; Durstock, Michael F; Vaia, Richard A

2014-12-10

Demands to increase the stored energy density of electrostatic capacitors have spurred the development of materials with enhanced dielectric breakdown, improved permittivity, and reduced dielectric loss. Polymer nanocomposites (PNCs), consisting of a blend of amorphous polymer and dielectric nanofillers, have been studied intensely to satisfy these goals; however, nanoparticle aggregates, field localization due to dielectric mismatch between particle and matrix, and the poorly understood role of interface compatibilization have challenged progress. To expand the understanding of the inter-relation between these factors and, thus, enable rational optimization of low and high contrast PNC dielectrics, we compare the dielectric performance of matrix-free hairy nanoparticle assemblies (aHNPs) to blended PNCs in the regime of low dielectric contrast to establish how morphology and interface impact energy storage and breakdown across different polymer matrices (polystyrene, PS, and poly(methyl methacrylate), PMMA) and nanoparticle loadings (0-50% (v/v) silica). The findings indicate that the route (aHNP versus blending) to well-dispersed morphology has, at most, a minor impact on breakdown strength trends with nanoparticle volume fraction; the only exception being at intermediate loadings of silica in PMMA (15% (v/v)). Conversely, aHNPs show substantial improvements in reducing dielectric loss and maintaining charge/discharge efficiency. For example, low-frequency dielectric loss (1 Hz-1 kHz) of PS and PMMA aHNP films was essentially unchanged up to a silica content of 50% (v/v), whereas traditional blends showed a monotonically increasing loss with silica loading. Similar benefits are seen via high-field polarization loop measurements where energy storage for ∼15% (v/v) silica loaded PMMA and PS aHNPs were 50% and 200% greater than respective comparable PNC blends. Overall, these findings on low dielectric contrast PNCs clearly point to the performance benefits of

Fluoro-polymer functionalized graphene for flexible ferroelectric polymer-based high-k nanocomposites with suppressed dielectric loss and low percolation threshold.

PubMed

Yang, Ke; Huang, Xingyi; Fang, Lijun; He, Jinliang; Jiang, Pingkai

2014-12-21

Flexible nanodielectric materials with high dielectric constant and low dielectric loss have huge potential applications in the modern electronic and electric industry. Graphene sheets (GS) and reduced-graphene oxide (RGO) are promising fillers for preparing flexible polymer-based nanodielectric materials because of their unique two-dimensional structure and excellent electrical and mechanical properties. However, the easy aggregation of GS/RGO significantly limits the potential of graphene in enhancing the dielectric constant of polymer composites. In addition, the poor filler/matrix nanoscale interfacial adhesion also causes difficulties in suppressing the dielectric loss of the composites. In this work, using a facile and environmentally friendly approach, polydopamine coated RGO (PDA-RGO) and fluoro-polymer functionalized RGO (PF-PDA-RGO) were prepared. Compared with the RGO prepared by the conventional methods [i.e. hydrazine reduced-graphene oxide (H-RGO)] and PDA-RGO, the resulting PF-PDA-RGO nanosheets exhibit excellent dispersion in the ferroelectric polymer matrix [i.e. poly(vinylidene fluoride-co-hexafluoro propylene), P(VDF-HFP)] and strong interfacial adhesion with the matrix, leading to a low percolation threshold (fc = 1.06 vol%) and excellent flexibility for the corresponding nanocomposites. Among the three nanocomposites, the P(VDF-HFP)/PF-PDA-RGO nanocomposites exhibited the optimum performance (i.e. simultaneously having high dielectric constant and low dielectric loss). For instance, at 1000 Hz, the P(VDF-HFP) nanocomposite sample with 1.0 vol% PF-PDA-RGO has a dielectric constant of 107.9 and a dielectric loss of 0.070, showing good potential for dielectric applications. Our strategy provides a new pathway to prepare high performance flexible nanodielectric materials.

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

The Axial Compressive Strength of High Performance Polymer Fibers

DTIC Science & Technology

1985-03-01

consists of axially oriented graphitic microfibrils that have the strong and stiff graphite crystal basal plane oriented parallel to the long axis of the... microfibrils [3,4]. The synthetic rigid polymer fibers are represented by only one commercial material: the PPTA fibers produced by E.I. DuPont de...and/or microfibrils is presented. A potential energy balance analysis is used to calculate critical stresses for the onset of compressive buckling

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.

Molecularly imprinted polymer cartridges coupled on-line with high performance liquid chromatography for simple and rapid analysis of dextromethorphan in human plasma samples.

PubMed

Moein, Mohammad Mahdi; Javanbakht, Mehran; Akbari-Adergani, Behrouz

2011-04-01

In this paper, a novel method is described for automated determination of dextromethorphan in biological fluids using molecularly imprinted solid-phase extraction (MISPE) as a sample clean-up technique combined with high performance liquid chromatography (HPLC). The water-compatible molecularly imprinted polymers (MIPs) were prepared using methacrylic acid as functional monomer, ethylene glycol dimethacrylate as cross-linker, chloroform as porogen and dextromethorphan as template molecule. These imprinted polymers were used as solid-phase extraction sorbent for the extraction of dextromethorphan from human plasma samples. Various parameters affecting the extraction efficiency of the MIP cartridges were evaluated. The high selectivity of the sorbent coupled to the high performance liquid chromatographic system permitted a simple and rapid analysis of this drug in plasma samples with limits of detection (LOD) and quantification (LOQ) of 0.12 ng/mL and 0.35 ng/mL, respectively. The MIP selectivity was evaluated by analyzing of the dextromethorphan in presence of several substances with similar molecular structures and properties. Results from the HPLC analyses showed that the recoveries of dextromethorphan using MIP cartridges from human plasma samples in the range of 1-50 ng/mL were higher than 87%. Copyright © 2011 Elsevier B.V. All rights reserved.

Sewage sludge disintegration by combined treatment of alkaline+high pressure homogenization.

PubMed

Zhang, Yuxuan; Zhang, Panyue; Zhang, Guangming; Ma, Weifang; Wu, Hao; Ma, Boqiang

2012-11-01

Alkaline pretreatment combined with high pressure homogenization (HPH) was applied to promote sewage sludge disintegration. For sewage sludge with a total solid content of 1.82%, sludge disintegration degree (DD(COD)) with combined treatment was higher than the sum of DD(COD) with single alkaline and single HPH treatment. NaOH dosage ⩽0.04mol/L, homogenization pressure ⩽60MPa and a single homogenization cycle were the suitable conditions for combined sludge treatment. The combined sludge treatment showed a maximum DD(COD) of 59.26%. By regression analysis, the combined sludge disintegration model was established as 11-DD(COD)=0.713C(0.334)P(0.234)N(0.119), showing that the effect of operating parameters on sludge disintegration followed the order: NaOH dosage>homogenization pressure>number of homogenization cycle. The energy efficiency with combined sludge treatment significantly increased compared with that with single HPH treatment, and the high energy efficiency was achieved at low homogenization pressure with a single homogenization cycle. Copyright © 2012 Elsevier Ltd. All rights reserved.

Conjunction of Conducting Polymer Nanostructures with Macroporous Structured Graphene Thin Films for High-Performance Flexible Supercapacitors.

PubMed

Memon, Mushtaque A; Bai, Wei; Sun, Jinhua; Imran, Muhammad; Phulpoto, Shah Nawaz; Yan, Shouke; Huang, Yong; Geng, Jianxin

2016-05-11

Fabrication of hybridized structures is an effective strategy to promote the performances of graphene-based composites for energy storage/conversion applications. In this work, macroporous structured graphene thin films (MGTFs) are fabricated on various substrates including flexible graphene papers (GPs) through an ice-crystal-induced phase separation process. The MGTFs prepared on GPs (MGTF@GPs) are recognized with remarkable features such as interconnected macroporous configuration, sufficient exfoliation of the conductive RGO sheets, and good mechanical flexibility. As such, the flexible MGTF@GPs are demonstrated as a versatile conductive platform for depositing conducting polymers (CPs), e.g., polyaniline (PAn), polypyrrole, and polythiophene, through in situ electropolymerization. The contents of the CPs in the composite films are readily controlled by varying the electropolymerization time. Notably, electrodeposition of PAn leads to the formation of nanostructures of PAn nanofibers on the walls of the macroporous structured RGO framework (PAn@MGTF@GPs): thereafter, the PAn@MGTF@GPs display a unique structural feature that combine the nanostructures of PAn nanofibers and the macroporous structures of RGO sheets. Being used as binder-free electrodes for flexible supercapacitors, the PAn@MGTF@GPs exhibit excellent electrochemical performance, in particular a high areal specific capacity (538 mF cm(-2)), high cycling stability, and remarkable capacitive stability to deformation, due to the unique electrode structures.

Imidazolium-Based Polymeric Materials as Alkaline Anion-Exchange Fuel Cell Membranes

NASA Technical Reports Server (NTRS)

Narayan, Sri R.; Yen, Shiao-Ping S.; Reddy, Prakash V.; Nair, Nanditha

2012-01-01

Polymer electrolyte membranes that conduct hydroxide ions have potential use in fuel cells. A variety of polystyrene-based quaternary ammonium hydroxides have been reported as anion exchange fuel cell membranes. However, the hydrolytic stability and conductivity of the commercially available membranes are not adequate to meet the requirements of fuel cell applications. When compared with commercially available membranes, polystyrene-imidazolium alkaline membrane electrolytes are more stable and more highly conducting. At the time of this reporting, this has been the first such usage for imidazolium-based polymeric materials for fuel cells. Imidazolium salts are known to be electrochemically stable over wide potential ranges. By controlling the relative ratio of imidazolium groups in polystyrene-imidazolium salts, their physiochemical properties could be modulated. Alkaline anion exchange membranes based on polystyrene-imidazolium hydroxide materials have been developed. The first step was to synthesize the poly(styrene-co-(1-((4-vinyl)methyl)-3- methylimidazolium) chloride through a free-radical polymerization. Casting of this material followed by in situ treatment of the membranes with sodium hydroxide solutions provided the corresponding hydroxide salts. Various ratios of the monomers 4-chloromoethylvinylbenzine (CMVB) and vinylbenzine (VB) provided various compositions of the polymer. The preferred material, due to the relative ease of casting the film, and its relatively low hygroscopic nature, was a 2:1 ratio of CMVB to VB. Testing confirmed that at room temperature, the new membranes outperformed commercially available membranes by a large margin. With fuel cells now in use at NASA and in transportation, and with defense potential, any improvement to fuel cell efficiency is a significant development.

Development of toughened epoxy polymers for high performance composite and ablative applications

NASA Technical Reports Server (NTRS)

Allen, V. R.

1982-01-01

A survey of current procedures for the assessment of state of cure in epoxy polymers and for the evaluation of polymer toughness as related to nature of the crosslinking agent was made to facilitate a cause-effect study of the chemical modification of epoxy polymers. Various conformations of sample morphology were examined to identify testing variables and to establish optimum conditions for the selected physical test methods. Dynamic viscoelasticity testing was examined in conjunction with chemical analyses to allow observation of the extent of the curing reaction with size of the crosslinking agent the primary variable. Specifically the aims of the project were twofold: (1) to consider the experimental variables associated with development of "extent of cure" analysis, and (2) to assess methodology of fracture energy determination and to prescribe a meaningful and reproducible procedure. The following is separated into two categories for ease of presentation.

Lithium salt doped conjugated polymers as electron transporting materials for highly efficient blue polymer light-emitting diodes

NASA Astrophysics Data System (ADS)

Huang, Fei; Shih, Ping-I.; Liu, Michelle S.; Shu, Ching-Fong; Jen, Alex K.-Y.

2008-12-01

Highly efficient blue polymer light-emitting diodes (PLEDs) are fabricated using a conjugated polymer, poly[9,9-bis(2-(2-(2-diethanol-amino-ethoxy) ethoxy) ethyl) fluorene-alt-4, 4'-phenylether] as an electron transporting layer (ETL). It was found that the performance of these blue-emitting devices could be greatly improved if the ETL was doped with LiF or Li2CO3 salts. A bis[(4,6-di-fluorophenyl)-pyridinato-N, C2] (picolinate) Ir(III) (FIrpic) complex based blue phosphorescent PLED exhibited a maximum luminance efficiency of 20.3 cd/A with a luminance of 1600 cd/m2 at the current density of 7.9 mA/cm2 and drive voltage of 8.0 V.

Characterization of Laboratory Prepared Concrete Pastes Exposed to High Alkaline and High Sodium Salt Solutions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Langton, C. A.

The objective of this study was to identify potential chemical degradation mechanisms for the Saltstone Disposal Unit (SDU) concretes, which over the performance life of the structures may be exposed to highly alkaline sodium salt solutions containing sulfate, hydroxide, and other potentially corrosive chemicals in salt solution and saltstone flush water, drain water, leachate and / or pore solution. The samples analyzed in this study were cement pastes prepared in the SIMCO Technologies, Inc. concrete laboratory. They were based on the paste fractions of the concretes used to construct the Saltstone Disposal Units (SDUs). SDU 1 and 4 concrete pastesmore » were represented by the PV1 test specimens. The paste in the SDU 2, 3, 5, and 6 concrete was represented by the PV2 test specimens. SIMCO Technologies, Inc. selected the chemicals and proportions in the aggressive solutions to approximate proportions in the saltstone pore solution [2, 3, 5, and 6]. These test specimens were cured for 56 days in curing chamber before being immersed in aggressive solutions. After exposure, the samples were frozen to prevent additional chemical transport and reaction. Selected archived (retrieved from the freezer) samples were sent to the Savannah River National Laboratory (SRNL) for additional characterization using x-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive x-ray (EDX) spectroscopy. Characterization results are summarized in this report. In addition, a correlation between the oxide composition of the pastes and their chemical durability in the alkaline salt solutions is provided.« less

Fast stack activation procedure and effective long-term storage for high-performance polymer electrolyte membrane fuel cell

NASA Astrophysics Data System (ADS)

Yang, Seung Yong; Seo, Dong-Jun; Kim, Myeong-Ri; Seo, Min Ho; Hwang, Sun-Mi; Jung, Yong-Min; Kim, Beom-Jun; Yoon, Young-Gi; Han, Byungchan; Kim, Tae-Young

2016-10-01

Time-saving stack activation and effective long-term storage are one of most important issues that must be resolved for the commercialization of polymer electrolyte membrane fuel cell (PEMFC). Herein, we developed the cost-effective stack activation method to finish the whole activation within 30 min and the long-term storage method by using humidified N2 without any significant decrease in cell's performance for 30 days. Specifically, the pre-activation step with the direct injection of DI water into the stack and storage at 65 or 80 °C for 2 h increases the distinctive phase separation between the hydrophobic and hydrophilic regions in Nafion membrane, which significantly reduces the total activation time within 30 min. Additionally, the long-term storage with humidified N2 has no effect on the Pt oxidation and drying of Nafion membrane for 30 days due to its exergonic reaction in the cell. As a result, the high water content in Nafion membrane and the decrease of Pt oxidation are the critical factors that have a strong influence on the activation and long-term storage for high-performance PEMFC.

Characterization and performance of high power iron(VI) ferrate batteries

NASA Astrophysics Data System (ADS)

Walz, Kenneth A.; Suyama, Amy N.; Suyama, Wendy E.; Sene, Jeosadaque J.; Zeltner, Walter A.; Armacanqui, Edgar M.; Roszkowski, Andrew J.; Anderson, Marc A.

In this paper we report on the high power discharge performance and impedance characteristics of potassium ferrate (K 2FeO 4) and barium ferrate (BaFeO 4) cathodes in zinc alkaline dry cells. The results show that if ferrate materials can be packaged to maximize the cathode surface area, they may offer superior performance over electrolytic manganese dioxide at operating voltages exceeding 1.6 V and currents as high as 100 mA/g of active material.

Highly elastic polymer solutions under shear: Polymer migration, viscoelastic instabilities, and anomalous rheology

DOE Office of Scientific and Technical Information (OSTI.GOV)

MacDonald, M.J.; Muller, S.J.

1996-12-31

The use of highly elastic polymer solutions has been remarkably successful in elucidating the behavior of polymeric materials under flowing conditions. Here, we present the results of an extensive experimental study into the shear behavior of an athermal, dilute, binary polymer solution that is believed to be free of many of these effects. Under extended shearing, we observe the migration of polymer species: after shearing for several hundred hours, concentrations that are more than double the initial uniform value can be achieved. Although the solutions are well-described by dumbbell models in shear flows on short-time scales, theoretical predictions substantially underestimatemore » the rate of migration. Flow visualization and rheometric experiments suggest that the origin of this discrepancy could be the anomalous long-time rheology of these solutions. While these fluids display the well-known elastic instability in cone and plate flow above a critical Deborah number, extended shearing reveals that the toroidal secondary flow is eventually replaced by a purely azimuthal shearing flow. In addition, when sheared below the critical condition for the instability, the solutions exhibit a slow but reversible decay in normal stresses. The shear-induced migration of polymer species has been predicted by numerous theoretical studies. However, observations on the highly elastic polymer solutions that are most likely to show polymer migration, are complicated by a number of different physical processes that occur as a result of shearing. These phenomena, which include shear-induced phase separation, elastically-induced hydrodynamic instabilities, mixed solvent effects, shear-induced aggregation, and anomalous transient shear and normal stress behavior are often observed at times earlier than and at shear rates less than those where migration is predicted to occur; hence, the experimental detection of polymer migration has been thwarted by these other physical processes.« less

Joint Strength Control at the Fiber/Matrix Interface during the Production of Polymer Composite Materials Reinforced with High Performance Fibers

NASA Astrophysics Data System (ADS)

Kudinov, Vladimir V.; Korneeva, Natalia V.

2010-06-01

The paper presents the results obtained in the study of the joint strength between polymer matrix and high performance polyethylene fiber. The fiber/matrix joints simulate the unit cell of the fiber-reinforced composite materials. Effect of heat treatment on the composite properties at the interface was estimated by a multifilament wet-pull-out method. It was found that the joint strength may be increased with the help of extra heart treatment. Both the energy to peak load and the energy to failure for CM joints at various stages of loading were determined.

Production of lignin based insoluble polymers (anionic hydrogels) by C. versicolor.

PubMed

Brzonova, Ivana; Kozliak, Evguenii I; Andrianova, Anastasia A; LaVallie, Audrey; Kubátová, Alena; Ji, Yun

2017-12-13

Unlike previous lignin biodegradation studies, white rot fungi were used to produce functional biopolymers from Kraft lignin. Lignin-based polymers (hydrogel precursors) partially soluble in both aqueous and organic solvents were produced employing a relatively fast (6 days) enzymation of Kraft lignin with basidiomycetes, primarily Coriolus versicolor, pre-grown on kenaf/lignin agar followed by either vacuum evaporation or acid precipitation. After drying followed by a treatment with alkaline water, this intermediate polymer became a pH-sensitive anionic hydrogel insoluble in either aqueous or organic solvents. The yield of this polymer increased from 20 to 72 wt% with the addition of 2% dimethylsulfoxide to distilled water used as a medium. The mechanical stability and buffering capacity of this hydrogel can be adjusted by washing the intermediate polymer/hydrogel precursor prior to drying with solvents of different polarity (water, methanol or ethanol). Any of these polymers featured a significant thermal resilience assessed as a high thermostable "coked" fraction in thermal carbon analysis, apparently resulting from significant covalent cross-linking that occurs during the treatment of their intermediate precursors.

Low-heat, mild alkaline pretreatment of switchgrass for anaerobic digestion.

PubMed

Jin, Guang; Bierma, Tom; Walker, Paul M

2014-01-01

This study examines the effectiveness of alkaline pretreatment under mild heat conditions (100°C or 212°F) on the anaerobic co-digestion of switchgrass. The effects of alkaline concentration, types of alkaline, heating time and rinsing were evaluated. In addition to batch studies, continuous-feed studies were performed in triplicate to identify potential digester operational problems caused by switchgrass co-digestion while accounting for uncertainty due to digester variability. Few studies have examined anaerobic digestion of switchgrass or the effects of mild heating to enhance alkaline pretreatment prior to biomass digestion. Results indicate that pretreatment can significantly enhance digestion of coarse-ground (≤ 0.78 cm particle size) switchgrass. Energy conversion efficiency as high as 63% was observed, and was comparable or superior to fine-grinding as a pretreatment method. The optimal NaOH concentration was found to be 5.5% (wt/wt alkaline/biomass) with a 91.7% moisture level. No evidence of operational problems such as solids build-up, poor mixing, or floating materials were observed. These results suggest the use of waste heat from a generator could reduce the concentration of alkaline required to adequately pretreat lignocellulosic feedstock prior to anaerobic digestion.

Performance assessment of polymer based electrodes for in vitro electrophysiological sensing: the role of the electrode impedance

NASA Astrophysics Data System (ADS)

Medeiros, Maria C. R.; Mestre, Ana L. G.; Inácio, Pedro M. C.; Santos, José M. L.; Araujo, Inês M.; Bragança, José; Biscarini, Fabio; Gomes, Henrique L.

2016-09-01

Conducting polymer electrodes based on poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) are used to record extracellular signals from autonomous cardiac contractile cells and glioma cell cultures. The performance of these conducting polymer electrodes is compared with Au electrodes. A small-signal impedance analysis shows that in the presence of an electrolyte, both Au and polymer electrodes establish high capacitive double-layers. However, the polymer/electrolyte interfacial resistance is 3 orders of magnitude lower than the resistance of the metal/electrolyte interface. The polymer low interfacial resistance minimizes the intrinsic thermal noise and increases the system sensitivity. However, when measurements are carried out in current mode a low interfacial resistance partially acts as a short circuit of the interfacial capacitance, this affects the signal shape.

Grace DAKASEP alkaline battery separator

NASA Technical Reports Server (NTRS)

Giovannoni, R. T.; Lundquist, J. T.; Choi, W. M.

1987-01-01

The Grace DAKASEP separator was originally developed as a wicking layer for nickel-zinc alkaline batteries. The DAKASEP is a filled non-woven separator which is flexible and heat sealable. Through modification of formulation and processing variables, products with a variety of properties can be produced. Variations of DAKASEP were tested in Ni-H2, Ni-Zn, Ni-Cd, and primary alkaline batteries with good results. The properties of DAKASEP which are optimized for Hg-Zn primary batteries are shown in tabular form. This separator has high tensile strength, 12 micron average pore size, relatively low porosity at 46-48 percent, and consequently moderately high resistivity. Versions were produced with greater than 70 percent porosity and resistivities in 33 wt percent KOH as low as 3 ohm cm. Performance data for Hg-Zn E-1 size cells containing DAKASEP with the properties shown in tabular form, are more reproducible than data obtained with a competitive polypropylene non-woven separator. In addition, utilization of active material is in general considerably improved.

The effect of environmental and process parameters on flocculation treatment of high dry matter swine manure with polymers.

PubMed

Masse, Lucie; Massé, Daniel I

2010-08-01

This paper reports on the effects of environmental conditions and process parameters on flocculation of high dry matter (average DM of 7.3%) swine manure with cationic polymers with 10%, 35%, and 55% charge densities (CDs). Polymer solutions prepared with hard and distilled water allowed similar suspended solids (SS) reductions in the initial 24h. After 3-7 days at 20 degrees C, however, the efficiency of the hard water solutions started to decline, while the polymers made with distilled water maintained their performance for up to 10 days. The 10% CD polymer was considerably less affected than the 35% CD polymer by the age of the hard water solutions. During polymer injection, minimum velocity gradients (G) of 108 and 253 s(-1) were required to maximized efficiency of the 10% and 35% CD polymer, respectively. Flocculation mixing velocities up to 84 s(-1) and mixing times between 1 and 30 min had no effect on polymer efficiency. However, mixing at 22s(-1) for more than 30 min decreased SS reduction. Adding polymer in multiple injections did not improve the efficiency of medium and high CD polymers, and adversely affected that of the low CD polymer, maybe because of repeated rapid mixing cycles which ruptured the flocs. Polymer performance was not affected by operating temperature between 6 and 25 degrees C. These results were collected on a laboratory-scale apparatus and remain to be validated at larger scale. Crown Copyright 2010. Published by Elsevier Ltd. All rights reserved.

Predicting Carbonate Species Ionic Conductivity in Alkaline Anion Exchange Membranes

DTIC Science & Technology

2012-06-01

This method has been used previously with both PEM and AEM fuel cells and demonstrated its ability to accurately predict ionic conductivity [2,9,24...water. In an AMFC, the mobile species is a hydroxide ion (OH - ) and in a PEM fuel cell , the proton is solvated with a water molecule forming...membrane synthesis techniques have produced polymer electrolyte membranes that are capable of transporting anions in alkaline membrane fuel cells

para-Azaquinodimethane: A Compact Quinodimethane Variant as an Ambient Stable Building Block for High-Performance Low Band Gap Polymers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Xuncheng; He, Bo; Anderson, Christopher L.

Quinoidal structures incorporating expanded para-quinodimethane (p-QM) units have garnered great interest as functional organic electronic, optical, and magnetic materials. The direct use of the compact p-QM unit as an electronic building block, however, has been inhibited by the high reactivity conveyed by its biradical character. Herein, we introduce a stable p-QM variant, namely p-azaquinodimethane (p-AQM), that incorporates nitrogen atoms in the central ring and alkoxy substituents on the periphery to increase the stability of the quinoidal structure. The succinct synthesis from readily available precursors leads to regio- and stereospecific p-AQMs that can be readily integrated into the backbone of conjugatedmore » polymers. The quinoidal character of the p-AQM unit endows the resulting polymers with narrow band gaps and high carrier transport mobilities. The study of a series of copolymers employing different numbers of thiophene units revealed an unconventional trend in band gaps, which is distinct from the widely adopted donor-acceptor approach to tuning the band gaps of conjugated polymers. Theoretical calculations have shed light on the nature of this trend, which may provide a unique class of conjugated polymers with promising optical and electronic properties.« less

para-Azaquinodimethane: A Compact Quinodimethane Variant as an Ambient Stable Building Block for High-Performance Low Band Gap Polymers

DOE PAGES

Liu, Xuncheng; He, Bo; Anderson, Christopher L.; ...

2017-05-24

Quinoidal structures incorporating expanded para-quinodimethane (p-QM) units have garnered great interest as functional organic electronic, optical, and magnetic materials. The direct use of the compact p-QM unit as an electronic building block, however, has been inhibited by the high reactivity conveyed by its biradical character. Herein, we introduce a stable p-QM variant, namely p-azaquinodimethane (p-AQM), that incorporates nitrogen atoms in the central ring and alkoxy substituents on the periphery to increase the stability of the quinoidal structure. The succinct synthesis from readily available precursors leads to regio- and stereospecific p-AQMs that can be readily integrated into the backbone of conjugatedmore » polymers. The quinoidal character of the p-AQM unit endows the resulting polymers with narrow band gaps and high carrier transport mobilities. The study of a series of copolymers employing different numbers of thiophene units revealed an unconventional trend in band gaps, which is distinct from the widely adopted donor-acceptor approach to tuning the band gaps of conjugated polymers. Theoretical calculations have shed light on the nature of this trend, which may provide a unique class of conjugated polymers with promising optical and electronic properties.« less

Nanoparticle-assisted high photoconductive gain in composites of polymer and fullerene.

PubMed

Chen, Hsiang-Yu; Lo, Michael K F; Yang, Guanwen; Monbouquette, Harold G; Yang, Yang

2008-09-01

Polymer-inorganic nanocrystal composites 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 solubility and distribution of the nanocrystals in the polymer matrices. Here we show that blending CdTe nanoparticles into a polymer-fullerene matrix followed by solvent annealing can achieve high photoconductive gain under low applied voltages. The surface capping ligand renders the nanoparticles highly soluble in the polymer blend, thereby enabling high CdTe loadings. An external quantum efficiency as high as approximately 8,000% at 350 nm was achieved at -4.5 V. Hole-dominant devices coupled with atomic force microscopy images show a higher concentration of nanoparticles near the cathode-polymer interface. The nanoparticles and trapped electrons assist hole injection into the polymer under reverse bias, contributing to efficiency values in excess of 100%.

High Performance Polymer Memory and Its Formation

DTIC Science & Technology

2007-04-26

the retention time of the device was performed to estimate the barrier height of the charge trap . The activation energy was approximated to be about...characteristics and presented a model to explain the mechanism of electrical switching in the device. By exploiting an electric-field induced charge transfer...electrical current in the high conductivity state would be due to some temperature-independent charge tunneling processes. The IV curves could be

Solvent immersion imprint lithography: A high-performance, semi-automated procedure

PubMed Central

Liyu, D. A.; Canul, A. J.; Vasdekis, A. E.

2017-01-01

We expand upon our recent, fundamental report on solvent immersion imprint lithography (SIIL) and describe a semi-automated and high-performance procedure for prototyping polymer microfluidics and optofluidics. The SIIL procedure minimizes manual intervention through a cost-effective (∼$200) and easy-to-assemble apparatus. We analyze the procedure's performance specifically for Poly (methyl methacrylate) microsystems and report repeatable polymer imprinting, bonding, and 3D functionalization in less than 5 min, down to 8 μm resolutions and 1:1 aspect ratios. In comparison to commercial approaches, the modified SIIL procedure enables substantial cost reductions, a 100-fold reduction in imprinting force requirements, as well as a more than 10-fold increase in bonding strength. We attribute these advantages to the directed polymer dissolution that strictly localizes at the polymer-solvent interface, as uniquely offered by SIIL. The described procedure opens new desktop prototyping opportunities, particularly for non-expert users performing live-cell imaging, flow-through catalysis, and on-chip gas detection. PMID:28798847

Lowering the operational temperature of all-solid-state lithium polymer cell with highly conductive and interfacially robust solid polymer electrolytes

NASA Astrophysics Data System (ADS)

Aldalur, Itziar; Martinez-Ibañez, Maria; Piszcz, Michal; Rodriguez-Martinez, Lide M.; Zhang, Heng; Armand, Michel

2018-04-01

Novel solid polymer electrolytes (SPEs), comprising of comb polymer matrix grafted with soft and disordered polyether moieties (Jeffamine®) and lithium bis(fluorosulfonyl)imide (LiFSI) are investigated in all-solid-state lithium metal (Li°) polymer cells. The LiFSI/Jeffamine-based SPEs are fully amorphous at room temperature with glass transitions as low as ca. -55 °C. They show higher ionic conductivities than conventional poly(ethylene oxide) (PEO)-based SPEs at ambient temperature region, and good electrochemical compatibility with Li° electrode. These exceptional properties enable the operational temperature of Li° | LiFePO4 cells to be decreased from an elevated temperature (70 °C) to room temperature. Those results suggest that LiFSI/Jeffamine-based SPEs can be promising electrolyte candidates for developing safe and high performance all-solid-state Li° batteries.

High-Performance Polymer Solar Cell with Single Active Material of Fully Conjugated Block Copolymer Composed of Wide-Band gap Donor and Narrow-Band gap Acceptor Blocks.

PubMed

Lee, Ji Hyung; Park, Chang Geun; Kim, Aesun; Kim, Hyung Jong; Kim, Youngseo; Park, Sungnam; Cho, Min Ju; Choi, Dong Hoon

2018-06-06

We synthesized a novel fully conjugated block copolymer, P3, in which a wide-band gap donor block (P1) was connected to a narrow-band gap acceptor block (P2). As P3 contains P1 block with a wide bandgap and P2 block with a narrow bandgap, it exhibits a very wide complementary absorption. Transient photoluminescence measurement using P3 dilute solution demonstrated intramolecular charge transfer between the P1 block and the P2 block, which was not observed in a P1/P2 blend solution. A P3 thin film showed complete PL quenching because the photoinduced inter-/intramolecular charge transfer states were effectively formed. This phenomenon can play an important role in the photovoltaic properties of P3-based polymer solar cells. A single active material polymer solar cell (SAMPSC) fabricated from P3 alone exhibited a high power conversion efficiency (PCE) of 3.87% with a high open-circuit voltage of 0.93 V and a short-circuit current of 8.26 mA/cm 2 , demonstrating a much better performance than a binary P1-/P2-based polymer solar cell (PCE = 1.14%). This result facilitates the possible improvement of the photovoltaic performance of SAMPSCs by inducing favorable nanophase segregation between p- and n blocks. In addition, owing to the high morphological stability of the block copolymer, excellent shelf-life was observed in a P3-based SAMPSC compared with a P1/P2-based PSC.

Metal- and Polymer-Matrix Composites: Functional Lightweight Materials for High-Performance Structures

NASA Astrophysics Data System (ADS)

Gupta, Nikhil; Paramsothy, Muralidharan

2014-06-01

The special topic "Metal- and Polymer-Matrix Composites" is intended to capture the state of the art in the research and practice of functional composites. The current set of articles related to metal-matrix composites includes reviews on functionalities such as self-healing, self-lubricating, and self-cleaning capabilities; research results on a variety of aluminum-matrix composites; and investigations on advanced composites manufacturing methods. In addition, the processing and properties of carbon nanotube-reinforced polymer-matrix composites and adhesive bonding of laminated composites are discussed. The literature on functional metal-matrix composites is relatively scarce compared to functional polymer-matrix composites. The demand for lightweight composites in the transportation sector is fueling the rapid development in this field, which is captured in the current set of articles. The possibility of simultaneously tailoring several desired properties is attractive but very challenging, and it requires significant advancements in the science and technology of composite materials. The progress captured in the current set of articles shows promise for developing materials that seem capable of moving this field from laboratory-scale prototypes to actual industrial applications.

Development and Characterization of New Donor-Acceptor Conjugated Polymers and Fullerene Nanoparticles for High Performance Bulk Heterojunction Solar Cells

DTIC Science & Technology

2011-01-14

thieno[3,4-c] pyrrole -4,6-dione (TPD)–based donor–acceptor polymer, PBTTPD, that exhibits high crystallinity and a low-lying highest occupied molecular...release; distribution unlimited 13. SUPPLEMENTARY NOTES 14. ABSTRACT Bithiophene/thieno[3,4-c] pyrrole -4,6-dione (TPD)?based donor?acceptor polymer...nearby fullerene acceptors. The electron-deficient thieno[3,4-c] pyrrole -4,6-dione (TPD) moiety exhibits a symmetric, rigidly fused, coplanar

Alkaline direct alcohol fuel cells using an anion exchange membrane

NASA Astrophysics Data System (ADS)

Matsuoka, Koji; Iriyama, Yasutoshi; Abe, Takeshi; Matsuoka, Masao; Ogumi, Zempachi

Alkaline direct alcohol fuel cells using an OH-form anion exchange membrane and polyhydric alcohols were studied. A high open circuit voltage of ca. 800 mV was obtained for a cell using Pt-Ru/C (anode) and Pt/C (cathode) at 323 K, which was about 100-200 mV higher than that for a DMFC using Nafion ®. The maximum power densities were in the order of ethylene glycol > glycerol > methanol > erythritol > xylitol. Silver catalysts were used as a cathode catalyst to fabricate alkaline fuel cells, since silver catalyst is almost inactive in the oxidation of polyhydric alcohols. Alkaline direct ethylene glycol fuel cells using silver as a cathode catalyst gave excellent performance because higher concentrations of fuel could be supplied to the anode.

Synthesis of molecular imprinted polymers for selective extraction of domperidone from human serum using high performance liquid chromatography with fluorescence detection.

PubMed

Salehi, Simin; Rasoul-Amini, Sara; Adib, Noushin; Shekarchi, Maryam

2016-08-01

In this study a novel method is described for selective quantization of domperidone in biological matrices applying molecular imprinted polymers (MIPs) as a sample clean up procedure using high performance liquid chromatography coupled with a fluorescence detector. MIPs were synthesized with chloroform as the porogen, ethylene glycol dimethacrylate as the crosslinker, methacrylic acid as the monomer, and domperidone as the template molecule. The new imprinted polymer was used as a molecular sorbent for separation of domperidone from serum. Molecular recognition properties, binding capacity and selectivity of MIPs were determined. The results demonstrated exceptional affinity for domperidone in biological fluids. The domperidone analytical method using MIPs was verified according to validation parameters, such as selectivity, linearity (5-80ng/mL, r(2)=0.9977), precision and accuracy (10-40ng/mL, intra-day=1.7-5.1%, inter-day=4.5-5.9%, and accuracy 89.07-98.9%).The limit of detection (LOD) and quantization (LOQ) of domperidone was 0.0279 and 0.092ng/mL, respectively. The simplicity and suitable validation parameters makes this a highly valuable selective bioequivalence method for domperidone analysis in human serum. Copyright © 2016 Elsevier B.V. All rights reserved.

Ultra-high performance size-exclusion chromatography in polar solvents.

PubMed

Vancoillie, Gertjan; Vergaelen, Maarten; Hoogenboom, Richard

2016-12-23

Size-exclusion chromatography (SEC) is amongst the most widely used polymer characterization methods in both academic and industrial polymer research allowing the determination of molecular weight and distribution parameters, i.e. the dispersity (Ɖ), of unknown polymers. The many advantages, including accuracy, reproducibility and low sample consumption, have contributed to the worldwide success of this analytical technique. The current generation of SEC systems have a stationary phase mostly containing highly porous, styrene-divinylbenzene particles allowing for a size-based separation of various polymers in solution but limiting the flow rate and solvent compatibility. Recently, sub-2μm ethylene-bridged hybrid (BEH) packing materials have become available for SEC analysis. These packing materials can not only withstand much higher pressures up to 15000psi but also show high spatial stability towards different solvents. Combining these BEH columns with the ultra-high performance LC (UHPLC) technology opens up UHP-SEC analysis, showing strongly reduced runtimes and unprecedented solvent compatibility. In this work, this novel characterization technique was compared to conventional SEC using both highly viscous and highly polar solvents as eluent, namely N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF) and methanol, focusing on the suitability of the BEH-columns for analysis of highly functional polymers. The results show a high functional group compatibility comparable with conventional SEC with remarkably short runtimes and enhanced resolution in methanol. Copyright © 2016 Elsevier B.V. All rights reserved.

Metabolic effect of alkaline additives and guanosine/gluconate in storage solutions for red blood cells.

PubMed

D'Alessandro, Angelo; Reisz, Julie A; Culp-Hill, Rachel; Korsten, Herbert; van Bruggen, Robin; de Korte, Dirk

2018-04-06

Over a century of advancements in the field of additive solutions for red blood cell (RBC) storage has made transfusion therapy a safe and effective practice for millions of recipients worldwide. Still, storage in the blood bank results in the progressive accumulation of metabolic alterations, a phenomenon that is mitigated by storage in novel storage additives, such as alkaline additive solutions. While novel alkaline additive formulations have been proposed, no metabolomics characterization has been performed to date. We performed UHPLC-MS metabolomics analyses of red blood cells stored in SAGM (standard additive in Europe), (PAGGSM), or alkaline additives SOLX, E-SOL 5 and PAG3M for either 1, 21, 35 (end of shelf-life in the Netherlands), or 56 days. Alkaline additives (especially PAG3M) better preserved 2,3-diphosphoglycerate and adenosine triphosphate (ATP). Deaminated purines such as hypoxanthine were predictive of hemolysis and morphological alterations. Guanosine supplementation in PAGGSM and PAG3M fueled ATP generation by feeding into the nonoxidative pentose phosphate pathway via phosphoribolysis. Decreased urate to hypoxanthine ratios were observed in alkaline additives, suggestive of decreased generation of urate and hydrogen peroxide. Despite the many benefits observed in purine and redox metabolism, alkaline additives did not prevent accumulation of free fatty acids and oxidized byproducts, opening a window for future alkaline formulations including (lipophilic) antioxidants. Alkalinization via different strategies (replacement of chloride anions with either high bicarbonate, high citrate/phosphate, or membrane impermeant gluconate) results in different metabolic outcomes, which are superior to current canonical additives in all cases. © 2018 AABB.

Raw materials for wood-polymer composites.

Treesearch

Craig Clemons

2008-01-01

To understand wood-plastic composites (WPCs) adequately, we must first understand the two main constituents. Though both are polymer based, they are very different in origin, structure, and performance. Polymers are high molecular weight materials whose performance is largely determined by its molecular architecture. In WPCs, a polymer matrix forms the continuous phase...

Evaluating Hydrogen Evolution and Oxidation in Alkaline Media to Establish Baselines

DOE PAGES

Alia, Shaun M.; Pivovar, Bryan S.

2018-04-28

This paper fills a significant gap in the literature for alkaline hydrogen evolution (HER) and oxidation (HOR) baseline performance, while reviewing the different variables that influence observed properties. Although high-performing HER-HOR catalysts in acidic electrolytes are too active to measure kinetic in rotating disk electrode (RDE) half-cells, under alkaline conditions RDE kinetics evaluations are relevant and half-cell performances are comparable to hydrogen pump data. This paper focuses on best practices to ensure that half-cell tests don't unnecessarily lower platinum group metal (PGM) performance or improve non-PGM performance. Specific aspects examined include experiments on PGMs minimizing the impact of impurities (electrolyte,more » cell material) and experiments on non-PGMs minimizing the impact from test protocols (counter electrode).« less

Evaluating Hydrogen Evolution and Oxidation in Alkaline Media to Establish Baselines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alia, Shaun M.; Pivovar, Bryan S.

This paper fills a significant gap in the literature for alkaline hydrogen evolution (HER) and oxidation (HOR) baseline performance, while reviewing the different variables that influence observed properties. Although high-performing HER-HOR catalysts in acidic electrolytes are too active to measure kinetic in rotating disk electrode (RDE) half-cells, under alkaline conditions RDE kinetics evaluations are relevant and half-cell performances are comparable to hydrogen pump data. This paper focuses on best practices to ensure that half-cell tests don't unnecessarily lower platinum group metal (PGM) performance or improve non-PGM performance. Specific aspects examined include experiments on PGMs minimizing the impact of impurities (electrolyte,more » cell material) and experiments on non-PGMs minimizing the impact from test protocols (counter electrode).« less

High-dielectric-constant polymers as high-energy-density (HED) field effect actuator and capacitor materials

NASA Astrophysics Data System (ADS)

Huang, Cheng; Zhang, Qiming

2004-07-01

The development of high dielectric constant polymers as active materials in high-performance devices is one of the challenges in polymeric electronics and opto-electronics such as flexible thin-film capacitors, memory devices and microactuators for deformable micromirror technology. A group of poly(vinylidene fluoridetrifluoroethylene) P(VDF-TrFE) based high-dielectric-constant fluoroterpolymers have been developed, which have high room-temperature dielectric constant (K>60) and very high strain level and high energy density. The longitudinal and transverse strain of these materials can reach about -7% and 4.5%, respectively, and the elastic energy density is around 1.1 J/cm^3 under a high electric field of 150 MV/m. The influence on the electromechanical properties of copolymerizing poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE) with a third monomer, chlorofluoroethylene (CFE), was investigated. It was found that increasing the CFE content from 0 to 8.5% slowly converts the ferroelectric structure of the copolymer to a relaxor ferroelectric system. This allows for a greatly decreased polarization and dielectric hysteresis and a much higher strain. Above 8.5%, increased CFE content substantially degrades the bulk crystallinity and the Young's modulus. These terpolymers have the potential to achieve above 10 J/cm^3 whole capacity energy density, which makes them good candidates for applications in pulse power capacitors. An all-polymer percolative composite by the combination of conductive polyaniline particles (K>10^5) within a fluoroterpolymer matrix, is introduced which exhibits very high dielectric constant (>7,000). The experimental results show that the dielectric behavior of this new class of percolative composites follows the prediction of the percolation theory and the analysis of the conductive percolation phenomena. The very high dielectric constant of the all-polymer composites which are also very flexible and possess elastic modulus not very

Diketopyrrolopyrrole Polymers with Thienyl and Thiazolyl Linkers for Application in Field-Effect Transistors and Polymer Solar Cells.

PubMed

Yu, Yaping; Wu, Yang; Zhang, Andong; Li, Cheng; Tang, Zheng; Ma, Wei; Wu, Yonggang; Li, Weiwei

2016-11-09

Conjugated polymers consisting of diketopyrrolopyrrole (DPP) units have been successfully applied in field-effect transistors (FETs) and polymer solar cells (PSCs), while most of the DPP polymers were designed as symmetric structures containing identical aromatic linkers. In this manuscript, we design a new asymmetric DPP polymer with varied aromatic linkers in the backbone for application in FETs and PSCs. The designation provides the chance to finely adjust the energy levels of conjugated polymers so as to influence the device performance. The asymmetric polymer exhibits highly crystalline properties, high hole mobilities of 3.05 cm 2 V -1 s -1 in FETs, and a high efficiency of 5.9% in PSCs with spectra response from 300 to 850 nm. Morphology investigation demonstrates that the asymmetric polymer has a large crystal domain in blended thin films, indicating that the solar cell performance can be further enhanced by optimizing the microphase separation. The study reveals that the asymmetric design via adjusting the aromatic linkers in DPP polymers is a useful route toward flexible electronic devices.

State-of-the-art of alkaline rechargeable batteries

NASA Astrophysics Data System (ADS)

Morioka, Y.; Narukawa, S.; Itou, T.

Alkaline rechargeable batteries represented by Ni-Cd and Ni-MH batteries are expanding their market, continuously meeting an increasing demand. Approximately 30 years have elapsed since the first sealed Ni-Cd battery was commercialized for consumer use, and the production of these alkaline batteries is still expanding. The high power performance and good cost performance of these batteries are the outstanding features, which are leading to new battery applications. Continuous R&D of many researchers and engineers has improved these features. Since first coming to the market in 1990, Ni-MH batteries have been extending their application as power sources for portable advanced information and communication equipment. Improvements in electrode materials and other components have increased the energy density of current Ni-MH batteries to values of 91 Wh/kg and 340 Wh/l. Recently, novel metallic alloys for hydrogen storage have been proposed to increase their capacity further, and further improvement in the performance of these batteries is expected.

High-performance, low-voltage, and easy-operable bending actuator based on aligned carbon nanotube/polymer composites.

PubMed

Chen, Luzhuo; Liu, Changhong; Liu, Ke; Meng, Chuizhou; Hu, Chunhua; Wang, Jiaping; Fan, Shoushan

2011-03-22

In this work, we show that embedding super-aligned carbon nanotube sheets into a polymer matrix (polydimethylsiloxane) can remarkably reduce the coefficient of thermal expansion of the polymer matrix by two orders of magnitude. Based on this unique phenomenon, we fabricated a new kind of bending actuator through a two-step method. The actuator is easily operable and can generate an exceptionally large bending actuation with controllable motion at very low driving DC voltages (<700 V/m). Furthermore, the actuator can be operated without electrolytes in the air, which is superior to conventional carbon nanotube actuators. Proposed electrothermal mechanism was discussed and confirmed by our experimental results. The exceptional bending actuation performance together with easy fabrication, low-voltage, and controllable motion demonstrates the potential ability of using this kind of actuator in various applicable areas, such as artificial muscles, microrobotics, microsensors, microtransducers, micromanipulation, microcantilever for medical applications, and so on.

Water evaporation on highly viscoelastic polymer surfaces.

PubMed

Pu, Gang; Severtson, Steven J

2012-07-03

Results are reported for a study on the evaporation of water droplets from a highly viscoelastic acrylic polymer surface. These are contrasted with those collected for the same measurements carried out on polydimethylsiloxane (PDMS). For PDMS, the evaporation process involves the expected multistep process including constant drop area, constant contact angle, and finally a combination of these steps until the liquid is gone. In contrast, water evaporation from the acrylic polymer shows a constant drop area mode throughout. Furthermore, during the evaporation process, the drop area actually expands on the acrylic polymer. The single mode evaporation process is consistent with formation of wetting structures, which cannot be propagated by the capillary forces. Expansion of the drop area is attributed to the influence of the drop capillary pressure. Furthermore, the rate of drop area expansion is shown to be dependent on the thickness of the polymer film.

Silicon Priming Created an Enhanced Tolerance in Alfalfa (Medicago sativa L.) Seedlings in Response to High Alkaline Stress.

PubMed

Liu, Duo; Liu, Miao; Liu, Xiao-Long; Cheng, Xian-Guo; Liang, Zheng-Wei

2018-01-01

Alkaline stress as a result of higher pH usually triggers more severe physiological damage to plants than that of saline stress with a neutral pH. In the present study, we demonstrated that silicon (Si) priming of alfalfa ( Medicago sativa L.) seedlings increased their tolerance to high alkaline stress situations. Gongnong No. 1 seedlings were subjected to alkaline stress simulated by 25 mM Na 2 CO 3 (pH 11.2). Alkaline stress greatly decreased the biomass and caused severe lodging or wilting of alfalfa seedlings. In contrast, the application of Si to alfalfa seedlings 36 h prior to the alkaline treatment significantly alleviated the damage symptoms and greatly increased the biomass and chlorophyll content. Because of being concomitant with increasing photosynthesis and water use efficiency, decreasing membrane injury and malondialdehyde content, and increasing peroxidase and catalase ascorbate activities in alfalfa leaves, thereby alleviating the triggered oxidative damage by alkaline stress to the plant. Furthermore, Si priming significantly decreased the accumulation of protein and proline content in alfalfa, thus reducing photosynthetic feedback repression. Si priming significantly accumulated more Na in the roots, but led to a decrease of Na accumulation and an increase of K accumulation in the leaves under alkaline stress. Meanwhile, Si priming decreased the accumulation of metal ions such as Mg, Fe, Mn, and Zn in the roots of alfalfa seedlings under alkaline stress. Collectively, these results suggested that Si is involved in the metabolic or physiological changes and has a potent priming effect on the alkaline tolerance of alfalfa seedlings. The present study indicated that Si priming is a new approach to improve the alkaline tolerance in alfalfa and provides increasing information for further exploration of the alkaline stress response at the molecular level in alfalfa.

Silicon Priming Created an Enhanced Tolerance in Alfalfa (Medicago sativa L.) Seedlings in Response to High Alkaline Stress

PubMed Central

Liu, Duo; Liu, Miao; Liu, Xiao-Long; Cheng, Xian-Guo; Liang, Zheng-Wei

2018-01-01

Alkaline stress as a result of higher pH usually triggers more severe physiological damage to plants than that of saline stress with a neutral pH. In the present study, we demonstrated that silicon (Si) priming of alfalfa (Medicago sativa L.) seedlings increased their tolerance to high alkaline stress situations. Gongnong No. 1 seedlings were subjected to alkaline stress simulated by 25 mM Na2CO3 (pH 11.2). Alkaline stress greatly decreased the biomass and caused severe lodging or wilting of alfalfa seedlings. In contrast, the application of Si to alfalfa seedlings 36 h prior to the alkaline treatment significantly alleviated the damage symptoms and greatly increased the biomass and chlorophyll content. Because of being concomitant with increasing photosynthesis and water use efficiency, decreasing membrane injury and malondialdehyde content, and increasing peroxidase and catalase ascorbate activities in alfalfa leaves, thereby alleviating the triggered oxidative damage by alkaline stress to the plant. Furthermore, Si priming significantly decreased the accumulation of protein and proline content in alfalfa, thus reducing photosynthetic feedback repression. Si priming significantly accumulated more Na in the roots, but led to a decrease of Na accumulation and an increase of K accumulation in the leaves under alkaline stress. Meanwhile, Si priming decreased the accumulation of metal ions such as Mg, Fe, Mn, and Zn in the roots of alfalfa seedlings under alkaline stress. Collectively, these results suggested that Si is involved in the metabolic or physiological changes and has a potent priming effect on the alkaline tolerance of alfalfa seedlings. The present study indicated that Si priming is a new approach to improve the alkaline tolerance in alfalfa and provides increasing information for further exploration of the alkaline stress response at the molecular level in alfalfa. PMID:29896213

Automated Fabrication Technologies for High Performance Polymer Composites

NASA Technical Reports Server (NTRS)

Shuart , M. J.; Johnston, N. J.; Dexter, H. B.; Marchello, J. M.; Grenoble, R. W.

1998-01-01

New fabrication technologies are being exploited for building high graphite-fiber-reinforced composite structure. Stitched fiber preforms and resin film infusion have been successfully demonstrated for large, composite wing structures. Other automatic processes being developed include automated placement of tacky, drapable epoxy towpreg, automated heated head placement of consolidated ribbon/tape, and vacuum-assisted resin transfer molding. These methods have the potential to yield low cost high performance structures by fabricating composite structures to net shape out-of-autoclave.

Control of New Copper Corrosion in High-Alkalinity Drinking Water using Orthophosphate - article

EPA Science Inventory

Research and field experience have shown that high-alkalinity waters can be associated with elevated copper levels in drinking water. The objective of this study was to document the application of orthophosphate to the distribution system of a building with a copper problem asso...

Jeffamine® based polymers as highly conductive polymer electrolytes and cathode binder materials for battery application

NASA Astrophysics Data System (ADS)

Aldalur, Itziar; Zhang, Heng; Piszcz, Michał; Oteo, Uxue; Rodriguez-Martinez, Lide M.; Shanmukaraj, Devaraj; Rojo, Teofilo; Armand, Michel

2017-04-01

We report a simple synthesis route towards a new type of comb polymer material based on polyether amines oligomer side chains (i.e., Jeffamine® compounds) and a poly(ethylene-alt-maleic anhydride) backbone. Reaction proceeds by imide ring formation through the NH2 group allowing for attachment of side chains. By taking advantage of the high configurational freedoms and flexibility of propylene oxide/ethylene oxide units (PO/EO) in Jeffamine® compounds, novel polymer matrices were obtained with good elastomeric properties. Fully amorphous solid polymer electrolytes (SPEs) based on lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and Jeffamine®-based polymer matrices show low glass transition temperatures around -40 °C, high ionic conductivities and good electrochemical stabilities. The ionic conductivities of Jeffamine-based SPEs (5.3 × 10-4 S cm-1 at 70 °C and 4.5 × 10-5 S cm-1 at room temperature) are higher than those of the conventional SPEs comprising of LiTFSI and linear poly(ethylene oxide) (PEO), due to the amorphous nature and the high concentration of mobile end-groups of the Jeffamine-based polymer matrices rather than the semi-crystalline PEO The feasibility of Jeffamine-based compounds in lithium metal batteries is further demonstrated by the implementation of Jeffamine®-based polymer as a binder for cathode materials, and the stable cycling of Li|SPE|LiFePO4 and Li|SPE|S cells using Jeffamine-based SPEs.

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.

Bone formation by three-dimensional stromal osteoblast culture in biodegradable polymer scaffolds

NASA Technical Reports Server (NTRS)

Ishaug, S. L.; Crane, G. M.; Miller, M. J.; Yasko, A. W.; Yaszemski, M. J.; Mikos, A. G.; McIntire, L. V. (Principal Investigator)

1997-01-01

Bone formation was investigated in vitro by culturing stromal osteoblasts in three-dimensional (3-D), biodegradable poly(DL-lactic-co-glycolic acid) foams. Three polymer foam pore sizes, ranging from 150-300, 300-500, and 500-710 microns, and two different cell seeding densities, 6.83 x 10(5) cells/cm2 and 22.1 x 10(5) cells/cm2, were examined over a 56-day culture period. The polymer foams supported the proliferation of seeded osteoblasts as well as their differentiated function, as demonstrated by high alkaline phosphatase activity and deposition of a mineralized matrix by the cells. Cell number, alkaline phosphatase activity, and mineral deposition increased significantly over time for all the polymer foams. Osteoblast foam constructs created by seeding 6.83 x 10(5) cells/cm2 on foams with 300-500 microns pores resulted in a cell density of 4.63 x 10(5) cells/cm2 after 1 day in culture; they had alkaline phosphatase activities of 4.28 x 10(-7) and 2.91 x 10(-6) mumol/cell/min on Days 7 and 28, respectively; and they had a cell density that increased to 18.7 x 10(5) cells/cm2 by Day 56. For the same constructs, the mineralized matrix reached a maximum penetration depth of 240 microns from the top surface of the foam and a value of 0.083 mm for mineralized tissue volume per unit of cross sectional area. Seeding density was an important parameter for the constructs, but pore size over the range tested did not affect cell proliferation or function. This study suggests the feasibility of using poly(alpha-hydroxy ester) foams as scaffolding materials for the transplantation of autogenous osteoblasts to regenerate bone tissue.

Accelerated Discovery of High-Refractive-Index Polymers Using First-Principles Modeling, Virtual High-Throughput Screening, and Data Mining

NASA Astrophysics Data System (ADS)

Afzal, Mohammad Atif Faiz; Cheng, Chong; Hachmann, Johannes

Organic materials with refractive index (RI) values higher than 1.7 have attracted considerable interest in recent years due to the tremendous potential for their application in optical, optometric, and optoelectronic devices, and thus for shaping technological innovation in numerous related areas. Our work is concerned with creating predictive models for the optical properties of organic polymers, which will guide our experimentalist partners and allow them to target the most promising candidates. The RI model is developed based on a synergistic combination of first-principles electronic structure theory and machine learning techniques. The RI values predicted for common polymers using this model are in very good agreement with the experimental values. We also benchmark different DFT approximations along with various basis sets for their predictive performance in this model. We demonstrate that this combination of first-principles and data modeling is both successful and highly economical in determining the RI values of a wide range of organic polymers. To accelerate the development process, we cast this modeling approach into the high-throughput screening, materials informatics, and rational design framework that is developed in the group. This framework is a powerful tool and has shown to be highly promising for rapidly identifying polymer candidates with exceptional RI values as well as discovering design rules for advanced materials.

Experimental study on the cool storage performance of super absorbent polymers for cool storage clothes

NASA Astrophysics Data System (ADS)

Li, Shidong; Mo, Caisong; Wang, Junze; Zheng, Jingfu; Tian, Ruhong

2017-11-01

In this paper, a kind of cool storage clothes which can cool the human body in high temperature condition is put forward. super absorbent polymers was selected as a cold storage material, through at the normal and extreme environment simulation, the cold storage materials were prepared with different composition, and their performance was tested. Test results show that:under normal temperature conditions, the 1:50 concentration of super absorbent polymers continued to release the longest cooling time, compared with pure water, cooling time extended 43 minutes by about 30%; under the condition of 37°C, the 1:100 concentration of super absorbent polymers continued to release the longest cooling time, compared with pure water, cooling time extended 105 minutes by about 50%.

Microbial communities associated with the anthropogenic, highly alkaline environment of a saline soda lime, Poland.

PubMed

Kalwasińska, Agnieszka; Felföldi, Tamás; Szabó, Attila; Deja-Sikora, Edyta; Kosobucki, Przemysław; Walczak, Maciej

2017-07-01

Soda lime is a by-product of the Solvay soda process for the production of sodium carbonate from limestone and sodium chloride. Due to a high salt concentration and alkaline pH, the lime is considered as a potential habitat of haloalkaliphilic and haloalkalitolerant microbial communities. This artificial and unique environment is nutrient-poor and devoid of vegetation, due in part to semi-arid, saline and alkaline conditions. Samples taken from the surface layer of the lime and from the depth of 2 m (both having pH ~11 and EC e up to 423 dS m -1 ) were investigated using culture-based (culturing on alkaline medium) and culture-independent microbiological approaches (microscopic analyses and pyrosequencing). A surprisingly diverse bacterial community was discovered in this highly saline, alkaline and nutrient-poor environment, with the bacterial phyla Proteobacteria (representing 52.8% of the total bacterial community) and Firmicutes (16.6%) showing dominance. Compared to the surface layer, higher bacterial abundance and diversity values were detected in the deep zone, where more stable environmental conditions may occur. The surface layer was dominated by members of the genera Phenylobacterium, Chelativorans and Skermanella, while in the interior layer the genus Fictibacillus was dominant. The culturable aerobic, haloalkaliphilic bacteria strains isolated in this study belonged mostly to the genus Bacillus and were closely related to the species Bacillus pseudofirmus, B. cereus, B. plakortidis, B. thuringensis and B. pumilus.

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

High-speed electro-optic polymers: mm-Wave applications and silica planar lightwave circuit integration

NASA Astrophysics Data System (ADS)

Chang, Daniel H.

The development of high speed polymer electro-optic modulators has seen steady and significant progress in recent years, enabling novel applications in RF-Photonics. Two of these are described in this Thesis: an Opto-Electronic Oscillator (OEO), which is a hybrid RF and optical oscillator capable of high spectral purity, and Photonic Time-Stretch, which is a signal processing technique for waveform spectral shifting with application to photonically-assisted A/D conversion. In both cases, the operating frequencies achieved have been the highest demonstrated to date. Application of this promising material to more complicated devices, however, is stymied by insertion loss performance. Current loss figures, while acceptable for single modulators, are too high for large arrays of modulators or intrinsically long devices such as AWGs or photonic-RF phase shifters. This is especially frustrating in light of a key virtue which polymers possess as a photonic material: its photolithographic process-ability makes patterning complex devices possible. Indeed, the current ascendancy of silica-based waveguide devices can be attributed largely to the same reason. In this Thesis, we also demonstrate the first hybrid device composed of silica planar lightwave circuits (PLCs) and polymer planar waveguides. Our approach utilizes grayscale lithography to enable vertical coupling between polymer and silica layers, minimizing entanglement of their respective fabrication processes. We have achieved coupling excess loss figures on the order of 1dB. We believe this is the natural next step in the development of electro-optic polymer devices. The two technologies are highly complementary. Silica PLCs, with excellent propagation loss and fiber coupling, are ideally suited for long passive waveguiding. By endowing them with the high-speed phase shifting capability offered by polymers, active wideband photonic devices of increasing complexity and array size can be contemplated.

Polymer-impregnated bridge slabs : performance over 10 years.

DOT National Transportation Integrated Search

1990-01-01

This report presents the results of a study to evaluate the performance over a 10-year period of slabs that were impregnated to a depth of about 1 in with a monomer that was subsequently polymerized (shallow polymer impregnation). The slabs were used...

Coupling alkaline pre-extraction with alkaline-oxidative post-treatment of corn stover to enhance enzymatic hydrolysis and fermentability.

PubMed

Liu, Tongjun; Williams, Daniel L; Pattathil, Sivakumar; Li, Muyang; Hahn, Michael G; Hodge, David B

2014-04-03

A two-stage chemical pretreatment of corn stover is investigated comprising an NaOH pre-extraction followed by an alkaline hydrogen peroxide (AHP) post-treatment. We propose that conventional one-stage AHP pretreatment can be improved using alkaline pre-extraction, which requires significantly less H2O2 and NaOH. To better understand the potential of this approach, this study investigates several components of this process including alkaline pre-extraction, alkaline and alkaline-oxidative post-treatment, fermentation, and the composition of alkali extracts. Mild NaOH pre-extraction of corn stover uses less than 0.1 g NaOH per g corn stover at 80°C. The resulting substrates were highly digestible by cellulolytic enzymes at relatively low enzyme loadings and had a strong susceptibility to drying-induced hydrolysis yield losses. Alkaline pre-extraction was highly selective for lignin removal over xylan removal; xylan removal was relatively minimal (~20%). During alkaline pre-extraction, up to 0.10 g of alkali was consumed per g of corn stover. AHP post-treatment at low oxidant loading (25 mg H2O2 per g pre-extracted biomass) increased glucose hydrolysis yields by 5%, which approached near-theoretical yields. ELISA screening of alkali pre-extraction liquors and the AHP post-treatment liquors demonstrated that xyloglucan and β-glucans likely remained tightly bound in the biomass whereas the majority of the soluble polymeric xylans were glucurono (arabino) xylans and potentially homoxylans. Pectic polysaccharides were depleted in the AHP post-treatment liquor relative to the alkaline pre-extraction liquor. Because the already-low inhibitor content was further decreased in the alkaline pre-extraction, the hydrolysates generated by this two-stage pretreatment were highly fermentable by Saccharomyces cerevisiae strains that were metabolically engineered and evolved for xylose fermentation. This work demonstrates that this two-stage pretreatment process is well suited for

Coupling alkaline pre-extraction with alkaline-oxidative post-treatment of corn stover to enhance enzymatic hydrolysis and fermentability

PubMed Central

2014-01-01

Background A two-stage chemical pretreatment of corn stover is investigated comprising an NaOH pre-extraction followed by an alkaline hydrogen peroxide (AHP) post-treatment. We propose that conventional one-stage AHP pretreatment can be improved using alkaline pre-extraction, which requires significantly less H2O2 and NaOH. To better understand the potential of this approach, this study investigates several components of this process including alkaline pre-extraction, alkaline and alkaline-oxidative post-treatment, fermentation, and the composition of alkali extracts. Results Mild NaOH pre-extraction of corn stover uses less than 0.1 g NaOH per g corn stover at 80°C. The resulting substrates were highly digestible by cellulolytic enzymes at relatively low enzyme loadings and had a strong susceptibility to drying-induced hydrolysis yield losses. Alkaline pre-extraction was highly selective for lignin removal over xylan removal; xylan removal was relatively minimal (~20%). During alkaline pre-extraction, up to 0.10 g of alkali was consumed per g of corn stover. AHP post-treatment at low oxidant loading (25 mg H2O2 per g pre-extracted biomass) increased glucose hydrolysis yields by 5%, which approached near-theoretical yields. ELISA screening of alkali pre-extraction liquors and the AHP post-treatment liquors demonstrated that xyloglucan and β-glucans likely remained tightly bound in the biomass whereas the majority of the soluble polymeric xylans were glucurono (arabino) xylans and potentially homoxylans. Pectic polysaccharides were depleted in the AHP post-treatment liquor relative to the alkaline pre-extraction liquor. Because the already-low inhibitor content was further decreased in the alkaline pre-extraction, the hydrolysates generated by this two-stage pretreatment were highly fermentable by Saccharomyces cerevisiae strains that were metabolically engineered and evolved for xylose fermentation. Conclusions This work demonstrates that this two

High-Performance As-Cast Nonfullerene Polymer Solar Cells with Thicker Active Layer and Large Area Exceeding 11% Power Conversion Efficiency.

PubMed

Fan, Qunping; Wang, Yan; Zhang, Maojie; Wu, Bo; Guo, Xia; Jiang, Yufeng; Li, Wanbin; Guo, Bing; Ye, Chennan; Su, Wenyan; Fang, Jin; Ou, Xuemei; Liu, Feng; Wei, Zhixiang; Sum, Tze Chien; Russell, Thomas P; Li, Yongfang

2018-02-01

In this work, a nonfullerene polymer solar cell (PSC) based on a wide bandgap polymer donor PM6 containing fluorinated thienyl benzodithiophene (BDT-2F) unit and a narrow bandgap small molecule acceptor 2,2'-((2Z,2'Z)-((4,4,9,9-tetrahexyl-4,9-dihydro-s-indaceno[1,2-b:5,6-b']dithiophene-2,7-diyl)bis(methanylylidene))bis(3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile (IDIC) is developed. In addition to matched energy levels and complementary absorption spectrum with IDIC, PM6 possesses high crystallinity and strong π-π stacking alignment, which are favorable to charge carrier transport and hence suppress recombination in devices. As a result, the PM6:IDIC-based PSCs without extra treatments show an outstanding power conversion efficiency (PCE) of 11.9%, which is the record value for the as-cast PSC devices reported in the literature to date. Moreover, the device performances are insensitive to the active layer thickness (≈95-255 nm) and device area (0.20-0.81 cm 2 ) with PCEs of over 11%. Besides, the PM6:IDIC-based flexible PSCs with a large device area of 1.25 cm 2 exhibit a high PCE of 6.54%. These results indicate that the PM6:IDIC blend is a promising candidate for future roll-to-roll mass manufacturing and practical application of highly efficient PSCs. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Transient alkalinization of the leaf apoplast stiffens the cell wall during onset of chloride salinity in corn leaves.

PubMed

Geilfus, Christoph-Martin; Tenhaken, Raimund; Carpentier, Sebastien Christian

2017-11-17

During chloride salinity, the pH of the leaf apoplast (pH apo ) transiently alkalizes. There is an ongoing debate about the physiological relevance of these stress-induced pH apo changes. Using proteomic analyses of expanding leaves of corn ( Zea mays L.), we show that this transition in pH apo conveys functionality by (i) adjusting protein abundances and (ii) affecting the rheological properties of the cell wall. pH apo was monitored in planta via microscopy-based ratio imaging, and the leaf-proteomic response to the transient leaf apoplastic alkalinization was analyzed via ultra-high performance liquid chromatography-MS. This analysis identified 1459 proteins, of which 44 exhibited increased abundance specifically through the chloride-induced transient rise in pH apo These elevated protein abundances did not directly arise from high tissue concentrations of Cl - or Na + but were due to changes in the pH apo Most of these proteins functioned in growth-relevant processes and in the synthesis of cell wall-building components such as arabinose. Measurements with a linear-variable differential transducer revealed that the transient alkalinization rigidified ( i.e. stiffened) the cell wall during the onset of chloride salinity. A decrease in t -coumaric and t -ferulic acids indicates that the wall stiffening arises from cross-linkage to cell wall polymers. We conclude that the pH of the apoplast represents a dynamic factor that is mechanistically coupled to cellular responses to chloride stress. By hardening the wall, the increased pH abrogates wall loosening required for cell expansion and growth. We conclude that the transient alkalinization of the leaf apoplast is related to salinity-induced growth reduction. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Highly efficient Cu(In,Ga)Se2 solar cells grown on flexible polymer films.

PubMed

Chirilă, Adrian; Buecheler, Stephan; Pianezzi, Fabian; Bloesch, Patrick; Gretener, Christina; Uhl, Alexander R; Fella, Carolin; Kranz, Lukas; Perrenoud, Julian; Seyrling, Sieghard; Verma, Rajneesh; Nishiwaki, Shiro; Romanyuk, Yaroslav E; Bilger, Gerhard; Tiwari, Ayodhya N

2011-09-18

Solar cells based on polycrystalline Cu(In,Ga)Se(2) absorber layers have yielded the highest conversion efficiency among all thin-film technologies, and the use of flexible polymer films as substrates offers several advantages in lowering manufacturing costs. However, given that conversion efficiency is crucial for cost-competitiveness, it is necessary to develop devices on flexible substrates that perform as well as those obtained on rigid substrates. Such comparable performance has not previously been achieved, primarily because polymer films require much lower substrate temperatures during absorber deposition, generally resulting in much lower efficiencies. Here we identify a strong composition gradient in the absorber layer as the main reason for inferior performance and show that, by adjusting it appropriately, very high efficiencies can be obtained. This implies that future manufacturing of highly efficient flexible solar cells could lower the cost of solar electricity and thus become a significant branch of the photovoltaic industry.

Design and synthesis of hierarchical MnO2 nanospheres/carbon nanotubes/conducting polymer ternary composite for high performance electrochemical electrodes.

PubMed

Hou, Ye; Cheng, Yingwen; Hobson, Tyler; Liu, Jie

2010-07-14

For efficient use of metal oxides, such as MnO(2) and RuO(2), in pseudocapacitors and other electrochemical applications, the poor conductivity of the metal oxide is a major problem. To tackle the problem, we have designed a ternary nanocomposite film composed of metal oxide (MnO(2)), carbon nanotube (CNT), and conducting polymer (CP). Each component in the MnO(2)/CNT/CP film provides unique and critical function to achieve optimized electrochemical properties. The electrochemical performance of the film is evaluated by cyclic voltammetry, and constant-current charge/discharge cycling techniques. Specific capacitance (SC) of the ternary composite electrode can reach 427 F/g. Even at high mass loading and high concentration of MnO(2) (60%), the film still showed SC value as high as 200 F/g. The electrode also exhibited excellent charge/discharge rate and good cycling stability, retaining over 99% of its initial charge after 1000 cycles. The results demonstrated that MnO(2) is effectively utilized with assistance of other components (fFWNTs and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) in the electrode. Such ternary composite is very promising for the next generation high performance electrochemical supercapacitors.

Pediatric reference intervals for alkaline phosphatase.

PubMed

Zierk, Jakob; Arzideh, Farhad; Haeckel, Rainer; Cario, Holger; Frühwald, Michael C; Groß, Hans-Jürgen; Gscheidmeier, Thomas; Hoffmann, Reinhard; Krebs, Alexander; Lichtinghagen, Ralf; Neumann, Michael; Ruf, Hans-Georg; Steigerwald, Udo; Streichert, Thomas; Rascher, Wolfgang; Metzler, Markus; Rauh, Manfred

2017-01-01

Interpretation of alkaline phosphatase activity in children is challenging due to extensive changes with growth and puberty leading to distinct sex- and age-specific dynamics. Continuous percentile charts from birth to adulthood allow accurate consideration of these dynamics and seem reasonable for an analyte as closely linked to growth as alkaline phosphatase. However, the ethical and practical challenges unique to pediatric reference intervals have restricted the creation of such percentile charts, resulting in limitations when clinical decisions are based on alkaline phosphatase activity. We applied an indirect method to generate percentile charts for alkaline phosphatase activity using clinical laboratory data collected during the clinical care of patients. A total of 361,405 samples from 124,440 patients from six German tertiary care centers and one German laboratory service provider measured between January 2004 and June 2015 were analyzed. Measurement of alkaline phosphatase activity was performed on Roche Cobas analyzers using the IFCC's photometric method. We created percentile charts for alkaline phosphatase activity in girls and boys from birth to 18 years which can be used as reference intervals. Additionally, data tables of age- and sex-specific percentile values allow the incorporation of these results into laboratory information systems. The percentile charts provided enable the appropriate differential diagnosis of changes in alkaline phosphatase activity due to disease and changes due to physiological development. After local validation, integration of the provided percentile charts into result reporting facilitates precise assessment of alkaline phosphatase dynamics in pediatrics.

Very High Performance High Nitrogen Energetic Ingredients and Energetic Polymers for Structural Components

DTIC Science & Technology

2011-12-31

have developed a vastly improved procedure for synthesis of the n- propyl ester that gives essentially quantitative yield and uses concentrated... Synthesis of n- propyl 4-aminofurazan-3-carboxylate. We next turned our attention to the synthesis of the amide. Again, the literature procedure is... synthesis and chemistry of 3-hydroxymethyl-4-amino[1,2,5]oxadiazole and 5) work on energetic polymers for structural components. 15. SUBJECT TERMS

Performance evaluation of cross-flow single-phase liquid-to-gas polymer tube heat exchanger

NASA Astrophysics Data System (ADS)

Dewanjee, Sujan; Hossain, Md. Rakibul; Rahman, Md. Ashiqur

2017-06-01

Reduced core weight and material cost, higher corrosion resistance are some of the major eye catching properties to study polymers over metal in heat exchanger applications in spite of the former's relatively low thermal conductivity and low strength. In the present study, performance of polymer parallel thin tube heat exchanger is numerically evaluated for cross flow liquid to air applications for a wide range of design and operating parameters such as tube diameter, thickness, fluid velocity and temperature, etc. using Computational Fluid Dynamics (CFD). Among a range of available polymeric materials, those with a moderate to high thermal conductivity and strength are selected for this study. A 90 cm × 1 cm single unit of polymer tubes, with appropriate number of tubes such that at least a gap of 5 mm is maintained in between the tubes, is used as a basic unit and multiple combination in the transverse direction of this single unit is simulated to measure the effect. The tube inner diameter is varied from 2 mm to 4 mm and the pressure drop is measured to have a relative idea of pumping cost. For each inner diameter the thickness is varied from .5 mm to 2.5 mm. The water velocity and the air velocity are varied from 0.4 m/s to 2 m/s and 1 m/s to 5 m/s, respectively. The performance of the polymer heat exchanger is compared with that of metal heat exchanger through and an optimum design for polymer heat exchanger is sought out.

A possible recycling method for high grade steels EAFD in polymer composites.

PubMed

Niubó, M; Fernández, A I; Chimenos, J M; Haurie, L

2009-11-15

This work evaluates the feasibility of incorporating electric arc furnace dust (EAFD), as filler in a polymer matrix, to obtain a moldable heavyweight sheet, useful for acoustic insulation in automotive industry. For this purpose EAFD from a steel factory that manufactures high quality steels, was characterized and different formulations of composites were prepared. Physical and mechanical properties, as well as fire behaviour were tested and compared with a polymer composite compounded with common mineral fillers. Optimum formulation with 25% EAFD fulfils the RoHs Directive used by automotive industry to regulate heavy metals content. Leaching test was also performed on prepared composites to classify the material after use.

High-intensity pulse light sintering of silver nanowire transparent films on polymer substrates: the effect of the thermal properties of substrates on the performance of silver films.

PubMed

Jiu, Jinting; Sugahara, Tohru; Nogi, Masaya; Araki, Teppei; Suganuma, Katsuaki; Uchida, Hiroshi; Shinozaki, Kenji

2013-12-07

Silver nanowire (AgNW) films with a random mesh structure have attracted considerable attention as high-performance flexible transparent electrodes that can replace the expensive and brittle ITO-sputtered films widely used in displays, touch screens, and solar cells. Methods such as heating, pressure treatment, and light treatment are usually used to obtain an optically transparent and electrically conductive film comparable to those of commercial ITO. However, the adhesion between the AgNW film and the substrate is so weak that other overcoatings or extra treatments are necessary. Here, a high-intensity pulsed light (HIPL) sintering technique was developed to rapidly and simply sinter the AgNW film and thus achieve strong adhesion and even high conductivity on these flexible polymer substrates which will be widely applied to the printing of electronic devices. The conductivity of the AgNW film closely depended on the thermal performance of substrates, and the adhesion was determined by the soft state of the substrate surface originating from the glass transition or melting of substrates with light intensity. The rapid sintering technique can be popularized to fabricate new devices on these polymer substrates by considering the thermal properties of the substrate to improve the performance of devices.

Fracture Simulation of Highly Crosslinked Polymer Networks: Triglyceride-Based Adhesives

NASA Astrophysics Data System (ADS)

Lorenz, Christian; Stevens, Mark; Wool, Richard

2003-03-01

The ACRES program at the U. of Delaware has shown that triglyceride oils derived from plants are a favorable alternative to the traditional adhesives. The triglyceride networks are formed from an initial mixture of styrene monomers, free-radical initiators and triglycerides. We have performed simulations to study the effect of physical composition and physical characteristics of the triglyceride network on the strength of triglyceride network. A coarse-grained, bead-spring model of the triglyceride system is used. The average triglyceride consists of 6 beads per chain, the styrenes are represented as a single bead and the initiators are two bead chains. The polymer network is formed using an off-lattice 3D Monte Carlo simulation, in which the initiators activate the styrene and triglyceride reactive sites and then bonds are randomly formed between the styrene and active triglyceride monomers producing a highly crosslinked polymer network. Molecular dynamics simulations of the network under tensile and shear strains were performed to determine the strength as a function of the network composition. The relationship between the network structure and its strength will also be discussed.

High-bandwidth and low-loss multimode polymer waveguides and waveguide components for high-speed board-level optical interconnects

NASA Astrophysics Data System (ADS)

Bamiedakis, N.; Chen, J.; Penty, R. V.; White, I. H.

2016-03-01

Multimode polymer waveguides are being increasingly considered for use in short-reach board-level optical interconnects as they exhibit favourable optical properties and allow direct integration onto standard PCBs with conventional methods of the electronics industry. Siloxane-based multimode waveguides have been demonstrated with excellent optical transmission performance, while a wide range of passive waveguide components that offer routing flexibility and enable the implementation of complex on-board interconnection architectures has been reported. In recent work, we have demonstrated that these polymer waveguides can exhibit very high bandwidth-length products in excess of 30 GHz×m despite their highly-multimoded nature, while it has been shown that even larger values of > 60 GHz×m can be achieved by adjusting their refractive index profile. Furthermore, the combination of refractive index engineering and launch conditioning schemes can ensure high bandwidth (> 100 GHz×m) and high coupling efficiency (<1 dB) with standard multimode fibre inputs with relatively large alignment tolerances (~17×15 μm2). In the work presented here, we investigate the effects of refractive index engineering on the performance of passive waveguide components (crossings, bends) and provide suitable design rules for their on-board use. It is shown that, depending on the interconnection layout and link requirements, appropriate choice of refractive index profile can provide enhanced component performance, ensuring low loss interconnection and adequate link bandwidth. The results highlight the strong potential of this versatile optical technology for the formation of high-performance board-level optical interconnects with high routing flexibility.

Methyllithium-Doped Naphthyl-Containing Conjugated Microporous Polymer with Enhanced Hydrogen Storage Performance.

PubMed

Xu, Dan; Sun, Lei; Li, Gang; Shang, Jin; Yang, Rui-Xia; Deng, Wei-Qiao

2016-06-01

Hydrogen storage is a primary challenge for using hydrogen as a fuel. With ideal hydrogen storage kinetics, the weak binding strength of hydrogen to sorbents is the key barrier to obtain decent hydrogen storage performance. Here, we reported the rational synthesis of a methyllithium-doped naphthyl-containing conjugated microporous polymer with exceptional binding strength of hydrogen to the polymer guided by theoretical simulations. Meanwhile, the experimental results showed that isosteric heat can reach up to 8.4 kJ mol(-1) and the methyllithium-doped naphthyl-containing conjugated microporous polymer exhibited an enhanced hydrogen storage performance with 150 % enhancement compared with its counterpart naphthyl-containing conjugated microporous polymer. These results indicate that this strategy provides a direction for design and synthesis of new materials that meet the US Department of Energy (DOE) hydrogen storage target. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Polymer compositions, polymer films and methods and precursors for forming same

DOEpatents

Klaehn, John R; Peterson, Eric S; Orme, Christopher J

2013-09-24

Stable, high performance polymer compositions including polybenzimidazole (PBI) and a melamine-formaldehyde polymer, such as methylated, poly(melamine-co-formaldehyde), for forming structures such as films, fibers and bulky structures. The polymer compositions may be formed by combining polybenzimidazole with the melamine-formaldehyde polymer to form a precursor. The polybenzimidazole may be reacted and/or intertwined with the melamine-formaldehyde polymer to form the polymer composition. For example, a stable, free-standing film having a thickness of, for example, between about 5 .mu.m and about 30 .mu.m may be formed from the polymer composition. Such films may be used as gas separation membranes and may be submerged into water for extended periods without crazing and cracking. The polymer composition may also be used as a coating on substrates, such as metal and ceramics, or may be used for spinning fibers. Precursors for forming such polymer compositions are also disclosed.

Molecular Spring Enabled High-Performance Anode for Lithium Ion Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zheng, Tianyue; Jia, Zhe; Lin, Na

Flexible butyl interconnection segments are synthetically incorporated into an electronically conductive poly(pyrene methacrylate) homopolymer and its copolymer. The insertion of butyl segment makes the pyrene polymer more flexible, and can better accommodate deformation. This new class of flexible and conductive polymers can be used as a polymer binder and adhesive to facilitate the electrochemical performance of a silicon/graphene composite anode material for lithium ion battery application. They act like a “spring” to maintain the electrode mechanical and electrical integrity. High mass loading and high areal capacity, which are critical design requirements of high energy batteries, have been achieved in themore » electrodes composed of the novel binders and silicon/graphene composite material. A remarkable area capacity of over 5 mAh/cm 2 and volumetric capacity of over 1700 Ah/L have been reached at a high current rate of 333 mA/g.« less

Molecular Spring Enabled High-Performance Anode for Lithium Ion Batteries

DOE PAGES

Zheng, Tianyue; Jia, Zhe; Lin, Na; ...

2017-11-29

Flexible butyl interconnection segments are synthetically incorporated into an electronically conductive poly(pyrene methacrylate) homopolymer and its copolymer. The insertion of butyl segment makes the pyrene polymer more flexible, and can better accommodate deformation. This new class of flexible and conductive polymers can be used as a polymer binder and adhesive to facilitate the electrochemical performance of a silicon/graphene composite anode material for lithium ion battery application. They act like a “spring” to maintain the electrode mechanical and electrical integrity. High mass loading and high areal capacity, which are critical design requirements of high energy batteries, have been achieved in themore » electrodes composed of the novel binders and silicon/graphene composite material. A remarkable area capacity of over 5 mAh/cm 2 and volumetric capacity of over 1700 Ah/L have been reached at a high current rate of 333 mA/g.« less

The Opportunity for High-Performance Biomaterials from Methane

PubMed Central

Strong, Peter James; Laycock, Bronwyn; Mahamud, Syarifah Nuraqmar Syed; Jensen, Paul Douglas; Lant, Paul Andrew; Tyson, Gene; Pratt, Steven

2016-01-01

Polyhydroxyalkanoate (PHA) biopolymers are widely recognised as outstanding candidates to replace conventional petroleum-derived polymers. Their mechanical properties are good and can be tailored through copolymer composition, they are biodegradable, and unlike many alternatives, they do not rely on oil-based feedstocks. Further, they are the only commodity polymer that can be synthesised intracellularly, ensuring stereoregularity and high molecular weight. However, despite offering enormous potential for many years, they are still not making a significant impact. This is broadly because commercial uptake has been limited by variable performance (inconsistent polymer properties) and high production costs of the raw polymer. Additionally, the main type of PHA produced naturally is poly-3-hydroxybutyrate (PHB), which has limited scope due to its brittle nature and low thermal stability, as well as its tendency to embrittle over time. Production cost is strongly impacted by the type of the feedstock used. In this article we consider: the production of PHAs from methanotrophs using methane as a cost-effective substrate; the use of mixed cultures, as opposed to pure strains; and strategies to generate a poly(3-hydroxybutyrate-co-3-hydroxyvalerate) copolymer (PHBV), which has more desirable qualities such as toughness and elasticity. PMID:27681905

The Opportunity for High-Performance Biomaterials from Methane.

PubMed

Strong, Peter James; Laycock, Bronwyn; Mahamud, Syarifah Nuraqmar Syed; Jensen, Paul Douglas; Lant, Paul Andrew; Tyson, Gene; Pratt, Steven

2016-02-03

Polyhydroxyalkanoate (PHA) biopolymers are widely recognised as outstanding candidates to replace conventional petroleum-derived polymers. Their mechanical properties are good and can be tailored through copolymer composition, they are biodegradable, and unlike many alternatives, they do not rely on oil-based feedstocks. Further, they are the only commodity polymer that can be synthesised intracellularly, ensuring stereoregularity and high molecular weight. However, despite offering enormous potential for many years, they are still not making a significant impact. This is broadly because commercial uptake has been limited by variable performance (inconsistent polymer properties) and high production costs of the raw polymer. Additionally, the main type of PHA produced naturally is poly-3-hydroxybutyrate (PHB), which has limited scope due to its brittle nature and low thermal stability, as well as its tendency to embrittle over time. Production cost is strongly impacted by the type of the feedstock used. In this article we consider: the production of PHAs from methanotrophs using methane as a cost-effective substrate; the use of mixed cultures, as opposed to pure strains; and strategies to generate a poly(3-hydroxybutyrate-co-3-hydroxyvalerate) copolymer (PHBV), which has more desirable qualities such as toughness and elasticity.

Evolved phase separation toward balanced charge transport and high efficiency in polymer solar cells.

PubMed

Fan, Haijun; Zhang, Maojie; Guo, Xia; Li, Yongfang; Zhan, Xiaowei

2011-09-01

Understanding effect of morphology on charge carrier transport within polymer/fullerene bulk heterojunction is necessary to develop high-performance polymer solar cells. In this work, we synthesized a new benzodithiophene-based polymer with good self-organization behavior as well as favorable morphology evolution of its blend films with PC(71)BM under improved processing conditions. Charge carrier transport behavior of blend films was characterized by space charge limited current method. Evolved blend film morphology by controlling blend composition and additive content gradually reaches an optimized state, featured with nanoscale fibrilla polymer phase in moderate size and balanced mobility ratio close to 1:1 for hole and electron. This optimized morphology toward more balanced charge carrier transport accounts for the best power conversion efficiency of 3.2%, measured under simulated AM 1.5 solar irradiation 100 mW/cm(2), through enhancing short circuit current and reducing geminate recombination loss.

A highly reversible anthraquinone-based anolyte for alkaline aqueous redox flow batteries

NASA Astrophysics Data System (ADS)

Cao, Jianyu; Tao, Meng; Chen, Hongping; Xu, Juan; Chen, Zhidong

2018-05-01

The development of electroactive organic materials for use in aqueous redox flow battery (RFB) electrolytes is highly attractive because of their structural flexibility, low cost and sustainability. Here, we report on a highly reversible anthraquinone-based anolyte (1,8-dihydroxyanthraquinone, 1,8-DHAQ) for alkaline aqueous RFB applications. Electrochemical measurements reveal the substituent position of hydroxyl groups for DHAQ isomers has a significant impact on the redox potential, electrochemical reversibility and water-solubility. 1,8-DHAQ shows the highest redox reversibility and rapidest mass diffusion among five isomeric DHAQs. The alkaline aqueous RFB using 1,8-DHAQ as the anolyte and potassium ferrocyanide as the catholyte yields open-circuit voltage approaching 1.1 V and current efficiency and capacity retention exceeding 99.3% and 99.88% per cycle, respectively. This aqueous RFB produces a maximum power density of 152 mW cm-2 at 100% SOC and 45 °C. Choline hydroxide was used as a hydrotropic agent to enhance the water-solubility of 1,8-DHAQ. 1,8-DHAQ has a maximum solubility of 3 M in 1 M KOH with 4 M choline hydroxide.

Diketopyrrolopyrrole Polymers for Organic Solar Cells.

PubMed

Li, Weiwei; Hendriks, Koen H; Wienk, Martijn M; Janssen, René A J

2016-01-19

Conjugated polymers have been extensively studied for application in organic solar cells. In designing new polymers, particular attention has been given to tuning the absorption spectrum, molecular energy levels, crystallinity, and charge carrier mobility to enhance performance. As a result, the power conversion efficiencies (PCEs) of solar cells based on conjugated polymers as electron donor and fullerene derivatives as electron acceptor have exceeded 10% in single-junction and 11% in multijunction devices. Despite these efforts, it is notoriously difficult to establish thorough structure-property relationships that will be required to further optimize existing high-performance polymers to their intrinsic limits. In this Account, we highlight progress on the development and our understanding of diketopyrrolopyrrole (DPP) based conjugated polymers for polymer solar cells. The DPP moiety is strongly electron withdrawing and its polar nature enhances the tendency of DPP-based polymers to crystallize. As a result, DPP-based conjugated polymers often exhibit an advantageously broad and tunable optical absorption, up to 1000 nm, and high mobilities for holes and electrons, which can result in high photocurrents and good fill factors in solar cells. Here we focus on the structural modifications applied to DPP polymers and rationalize and explain the relationships between chemical structure and organic photovoltaic performance. The DPP polymers can be tuned via their aromatic substituents, their alkyl side chains, and the nature of the π-conjugated segment linking the units along the polymer chain. We show that these building blocks work together in determining the molecular conformation, the optical properties, the charge carrier mobility, and the solubility of the polymer. We identify the latter as a decisive parameter for DPP-based organic solar cells because it regulates the diameter of the semicrystalline DPP polymer fibers that form in the photovoltaic blends with

High-quality graphene flakes exfoliated on a flat hydrophobic polymer

NASA Astrophysics Data System (ADS)

Pedrinazzi, Paolo; Caridad, José M.; Mackenzie, David M. A.; Pizzocchero, Filippo; Gammelgaard, Lene; Jessen, Bjarke S.; Sordan, Roman; Booth, Timothy J.; Bøggild, Peter

2018-01-01

We show that graphene supported on a hydrophobic and flat polymer surface results in flakes with extremely low doping and strain as assessed by their Raman spectroscopic characteristics. We exemplify this technique by micromechanical exfoliation of graphene on flat poly(methylmethacrylate) layers and demonstrate Raman peak intensity ratios I(2D)/I(G) approaching 10, similar to pristine freestanding graphene. We verify that these features are not an artifact of optical interference effects occurring at the substrate: they are similarly observed when varying the substrate thickness and are maintained when the environment of the graphene flake is completely changed, by encapsulating preselected flakes between hexagonal boron nitride layers. The exfoliation of clean, pristine graphene layers directly on flat polymer substrates enables high performance, supported, and non-encapsulated graphene devices for flexible and transparent optoelectronic studies. We additionally show that the access to a clean and supported graphene source leads to high-quality van der Waals heterostructures and devices with reproducible carrier mobilities exceeding 50 000 cm2 V-1 s-1 at room temperature.

Polymer Nanocomposite Materials with High Dielectric Permittivity and Low Dielectric Loss Properties

NASA Astrophysics Data System (ADS)

Toor, Anju

Materials with high dielectric permittivity have drawn increasing interests in recent years for their important applications in capacitors, actuators, and high energy density pulsed power. Particularly, polymer-based dielectrics are excellent candidates, owing to their properties such as high breakdown strength, low dielectric loss, flexibility and easy processing. To enhance the dielectric permittivity of polymer materials, typically, high dielectric constant filler materials are added to the polymer. Previously, ferroelectric and conductive fillers have been mainly used. However, such systems suffered from various limitations. For example, composites based on ferroelectric materials like barium titanate, exhibited high dielectric loss, and poor saturation voltages. Conductive fillers are used in the form of powder aggregates, and they may show 10-100 times enhancement in dielectric constant, however these nanoparticle aggregates cause the dielectric loss to be significant. Also, agglomerates limit the volume fraction of fillers in polymer and hence, the ability to achieve superior dielectric constants. Thus, the aggregation of nanoparticles is a significant challenge to their use to improve the dielectric permittivity. We propose the use of ligand-coated metal nanoparticle fillers to enhance the dielectric properties of the host polymer while minimizing dielectric loss by preventing nanoparticle agglomeration. The focus is on obtaining uniform dispersion of nanoparticles with no agglomeration by utilizing appropriate ligands/surface functionalizations on the gold nanoparticle surface. Use of ligand coated metal nanoparticles will enhance the dielectric constant while minimizing dielectric loss, even with the particles closely packed in the polymer matrix. Novel combinations of materials, which use 5 nm diameter metal nanoparticles embedded inside high breakdown strength polymer materials are evaluated. High breakdown strength polymer materials are chosen to allow

Efficient CsF interlayer for high and low bandgap polymer solar cell

NASA Astrophysics Data System (ADS)

Mitul, Abu Farzan; Sarker, Jith; Adhikari, Nirmal; Mohammad, Lal; Wang, Qi; Khatiwada, Devendra; Qiao, Qiquan

2018-02-01

Low bandgap polymer solar cells have a great deal of importance in flexible photovoltaic market to absorb sun light more efficiently. Efficient wide bandgap solar cells are always available in nature to absorb visible photons. The development and incorporation of infrared photovoltaics (IR PV) with wide bandgap solar cells can improve overall solar device performance. Here, we have developed an efficient low bandgap polymer solar cell with CsF as interfacial layer in regular structure. Polymer solar cell devices with CsF shows enhanced performance than Ca as interfacial layer. The power conversion efficiency of 4.5% has been obtained for PDPP3T based polymer solar cell with CsF as interlayer. Finally, an optimal thickness with CsF as interfacial layer has been found to improve the efficiency in low bandgap polymer solar cells.

New support for high-performance liquid chromatography based on silica coated with alumina particles.

PubMed

Silveira, José Leandro R; Dib, Samia R; Faria, Anizio M

2014-01-01

A new material based on silica coated with alumina nanoparticles was proposed for use as a chromatographic support for reversed-phase high-performance liquid chromatography. Alumina nanoparticles were synthesized by a sol-gel process in reversed micelles composed of sodium bis(2-ethylhexyl)sulfosuccinate, and the support material was formed by the self-assembly of alumina layers on silica spheres. Spectroscopic and (29)Si nuclear magnetic resonance results showed evidence of chemical bonds between the alumina nanoparticles and the silica spheres, while morphological characterizations showed that the aluminized silica maintained the morphological properties of silica desired for chromatographic purposes after alumina incorporation. Stability studies indicated that bare silica showed high dissolution (~83%), while the aluminized silica remained practically unchanged (99%) after passing one liter of the alkaline mobile phase, indicating high stability under alkaline conditions. The C18 bonded aluminized silica phase showed great potential for use in high-performance liquid chromatography to separate basic molecules in the reversed-phase mode.

A nonconjugated radical polymer glass with high electrical conductivity

NASA Astrophysics Data System (ADS)

Joo, Yongho; Agarkar, Varad; Sung, Seung Hyun; Savoie, Brett M.; Boudouris, Bryan W.

2018-03-01

Solid-state conducting polymers usually have highly conjugated macromolecular backbones and require intentional doping in order to achieve high electrical conductivities. Conversely, single-component, charge-neutral macromolecules could be synthetically simpler and have improved processibility and ambient stability. We show that poly(4-glycidyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl), a nonconjugated radical polymer with a subambient glass transition temperature, underwent rapid solid-state charge transfer reactions and had an electrical conductivity of up to 28 siemens per meter over channel lengths up to 0.6 micrometers. The charge transport through the radical polymer film was enabled with thermal annealing at 80°C, which allowed for the formation of a percolating network of open-shell sites in electronic communication with one another. The electrical conductivity was not enhanced by intentional doping, and thin films of this material showed high optical transparency.

Optimization of mechanical performance of oxidative nano-particle electrode nitrile butadiene rubber conducting polymer actuator.

PubMed

Kim, Baek-Chul; Park, S J; Cho, M S; Lee, Y; Nam, J D; Choi, H R; Koo, J C

2009-12-01

Present work delivers a systematical evaluation of actuation efficiency of a nano-particle electrode conducting polymer actuator fabricated based on Nitrile Butadiene Rubber (NBR). Attempts are made for maximizing mechanical functionality of the nano-particle electrode conducting polymer actuator that can be driven in the air. As the conducting polymer polypyrrole of the actuator is to be fabricated through a chemical oxidation polymerization process that may impose certain limitations on both electrical and mechanical functionality of the actuator, a coordinated study for optimization process of the actuator is necessary for maximizing its performance. In this article actuation behaviors of the nano-particle electrode polypyrrole conducting polymer is studied and an optimization process for the mechanical performance maximization is performed.

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.

Natural and synthetic mineral silicates as functional nanoparticles in polymer composites

NASA Astrophysics Data System (ADS)

Shao, Hua

A new strategy is described for the substantial enhancement of the barrier properties for both a thermoset epoxy polymer and a thermoplastic polyolefin by sandwiching a novel self-supported clay fabric film between thin polymer sheets. The success of this strategy is attributed to the high orientation of clay nanolayers in the paper-like clay fabric films and to the filling of the micro- or sub-micro sized voids between imperfectly tiled clay platelet edges by the polymer chains. Thermoplastic polyolefin-clay fabric film composites were fabricated by hot-pressing the clay films between two sheets of high density polyethylene (HDPE) films. The sandwiched composites exhibit more than a 30-fold decrease in O2 transmission rate with respect to the pure HDPE film. Impregnating the self-supported clay papers with epoxy pre-polymers successfully leads to thermoset composite films with more than 2-3 orders of magnitude reduction in O2 permeability in comparison to the pristine epoxy matrix. Owing to the promising use of synthetic Mg-saponite (denoted SAP) as epoxy polymer reinforcing agents, we investigated the cost-effective synthesis of SAP by replacing urea with sodium hydroxide as base source. Co-crystallization of new zeolite phases, such as garronite (denoted GIS) and cancrinite (denoted CAN), occurred along with SAP upon increasing the alkalinity of the reaction mixture. This finding represents the first example of the preparation of a CAN/SAP phase mixture. Moreover, pure-phase cancrinite with rod-like morphology up to several mum in length was synthesized under Mg-free conditions. Also, the Si/AI ratio within the synthesis gel has an influence on the chemical composition and textural properties of pure CAN crystals. Microporous cancrinite is a promising candidate for reinforcing epoxy polymers, considering that CAN represents a substantial fraction of the mixed CAN-SAP phase formed during the synthesis of saponite. Therefore, the reaction conditions (e

Polymer-Based Protein Engineering: Synthesis and Characterization of Armored, High Graft Density Polymer-Protein Conjugates.

PubMed

Carmali, Sheiliza; Murata, Hironobu; Cummings, Chad; Matyjaszewski, Krzysztof; Russell, Alan J

2017-01-01

Atom transfer radical polymerization (ATRP) from the surface of a protein can generate remarkably dense polymer shells that serve as armor and rationally tune protein function. Using straightforward chemistry, it is possible to covalently couple or display multiple small molecule initiators onto a protein surface. The chemistry is fine-tuned to be sequence specific (if one desires a single targeted site) at controlled density. Once the initiator is anchored on the protein surface, ATRP is used to grow polymers on protein surface, in situ. The technique is so powerful that a single-protein polymer conjugate molecule can contain more than 90% polymer coating by weight. If desired, stimuli-responsive polymers can be "grown" from the initiated sites to prepare enzyme conjugates that respond to external triggers such as temperature or pH, while still maintaining enzyme activity and stability. Herein, we focus mainly on the synthesis of chymotrypsin-polymer conjugates. Control of the number of covalently coupled initiator sites by changing the stoichiometric ratio between enzyme and the initiator during the synthesis of protein-initiator complexes allowed fine-tuning of the grafting density. For example, very high grafting density chymotrypsin conjugates were prepared from protein-initiator complexes to grow the temperature-responsive polymers, poly(N-isopropylacrylamide), and poly[N,N'-dimethyl(methacryloyloxyethyl) ammonium propane sulfonate]. Controlled growth of polymers from protein surfaces enables one to predictably manipulate enzyme kinetics and stability without the need for molecular biology-dependent mutagenesis. © 2017 Elsevier Inc. All rights reserved.

A Comparison of Water Diffusion in Polymer Based Fuel Cell and Reverse Osmosis Membrane Materials

NASA Astrophysics Data System (ADS)

Soles, Christopher; Frieberg, Bradley; Tarver, Jacob; Tyagi, Madhusudan; Jeong, Cheol; Chan, Edwin; Stafford, Christopher

Hydrated polymer membranes are critical in both fuel cells and water filtration and desalination. In both of these applications the membrane function (selectively transporting or separating ions) is coupled with the transport of water through the membrane. There is a significant need to understand the nature by which the water and ions distribute and move through these membranes. This presentation compares the transport mechanisms in in an ion containing block copolymer alkaline fuel cell membrane with that of a polyamide membrane that is used as the active layer in a reverse osmosis water desalination membrane. Small angle neutron scattering measurements are used to locally probe how water swells the different materials and quantitatively describe the distribution of water within the membrane microstructures. Quasielastic neutron scattering measurements are then used to separate the polymer dynamics of the host membranes from the dynamics of the water inside the membranes. This reveals that water moves at least an order of magnitude slower through the ion containing fuel cell membrane materials, consistent with a solution-diffusion model, while the water in the polyamide membranes moves faster, consistent with a pore-flow diffusion mechanism. These insights will be discussed in terms of a coupling of the water and polymer dynamics and design cues for high performance membrane materials.

Chemiluminescence-based pesticide biosensor utilizing the intelligent evolved properties of the enzyme alkaline phosphatase

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ayyagari, M.; Kamtekar, S.; Pande, R.

A methodology is described for immobilizing the enzyme alkaline phosphatase onto a glass surface using a novel biotinylated copolymer, poly(3-undecylthiophene-co-3- methanoithiophene). A streptavidin conjugate of alkaline phosphatase is used in this study. The biotinylated polymer is attached to the silanized glass surface via hydrophobic interactions and the enzyme is interfaced with the polymer through the classical biotin- streptavidin interaction. Alkaline phosphatase catalyzes the dephosphorylation of a macrocyclic compound, chloro-3-(4-methoxy spiro) (1,2 dioxetane-3-2`-tricyclo-) (3.3.1.1 )-(decani-4-yl) phenyl phosphate, to a species which emits energy by chemiluminescence. This chemiluminescence signal can be detected with a photomultiplier tube for enzymatic catalysis with the biocatalystmore » both in solution and immobilized on a glass surface. The signal generation is inhibited by the organophosphorus based insecticides such as paraoxon as well as nerve agents. We demonstrate in this study that a number of organophosphorus based insecticides inhibit the enzyme-mediated generation of chemiluminescence signal. This is true for the enzyme conjugate both free in solution and immobilized on a glass surface. In solution, the inhibition resembles the case of a partially uncompetitive system. By this type of inhibition we are able to detect pesticides down to about 50 ppb for the enzyme in solution. The pesticide detection limit of immobilized enzyme is currently being investigated. The enzyme is capable of a number of measurement cycles without significant loss of signal level.« less

Stabilizing the Performance of High-Capacity Sulfur Composite Electrodes by a New Gel Polymer Electrolyte Configuration.

PubMed

Agostini, Marco; Lim, Du Hyun; Sadd, Matthew; Fasciani, Chiara; Navarra, Maria Assunta; Panero, Stefania; Brutti, Sergio; Matic, Aleksandar; Scrosati, Bruno

2017-09-11

Increased pollution and the resulting increase in global warming are drawing attention to boosting the use of renewable energy sources such as solar or wind. However, the production of energy from most renewable sources is intermittent and thus relies on the availability of electrical energy-storage systems with high capacity and at competitive cost. Lithium-sulfur batteries are among the most promising technologies in this respect due to a very high theoretical energy density (1675 mAh g -1 ) and that the active material, sulfur, is abundant and inexpensive. However, a so far limited practical energy density, life time, and the scaleup of materials and production processes prevent their introduction into commercial applications. In this work, we report on a simple strategy to address these issues by using a new gel polymer electrolyte (GPE) that enables stable performance close to the theoretical capacity of a low cost sulfur-carbon composite with high loading of active material, that is, 70 % sulfur. We show that the GPE prevents sulfur dissolution and reduces migration of polysulfide species to the anode. This functional mechanism of the GPE membranes is revealed by investigating both its morphology and the Li-anode/GPE interface at various states of discharge/charge using Raman spectroscopy. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

Nano polypeptide particles reinforced polymer composite fibers.

PubMed

Li, Jiashen; Li, Yi; Zhang, Jing; Li, Gang; Liu, Xuan; Li, Zhi; Liu, Xuqing; Han, Yanxia; Zhao, Zheng

2015-02-25

Because of the intensified competition of land resources for growing food and natural textile fibers, there is an urgent need to reuse and recycle the consumed/wasted natural fibers as regenerated green materials. Although polypeptide was extracted from wool by alkaline hydrolysis, the size of the polypeptide fragments could be reduced to nanoscale. The wool polypeptide particles were fragile and could be crushed down to nano size again and dispersed evenly among polymer matrix under melt extrusion condition. The nano polypeptide particles could reinforce antiultraviolet capability, moisture regain, and mechanical properties of the polymer-polypeptide composite fibers.

Stirring Up Acceptor Phase and Controlling Morphology via Choosing Appropriate Rigid Aryl Rings as Lever Arms in Symmetry-Breaking Benzodithiophene for High-Performance Fullerene and Fullerene-Free Polymer Solar Cells.

PubMed

Liu, Deyu; Wang, Junyi; Gu, Chunyang; Li, Yonghai; Bao, Xichang; Yang, Renqiang

2018-02-01

Two series of new polymers with medium and wide bandgaps to match fullerene (PC 71 BM) and fullerene-free 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2',3'-d']-s-indaceno[1,2-b:5,6-b']dithiophene (ITIC) acceptors are designed and synthesized, respectively. For constructing the key donor building blocks, the effective symmetry-breaking strategy is employed. Two common aromatic rings (thiophene and benzene) are chosen as one side substituted groups in the asymmetric benzodithiophene (BDT) monomers. In addition, another rigid benzene ring is inserted between aryl and thioether in the side chains, which results in larger twisting and destroying the aggregation and forming longer lever arms. As a result, highly ordered polymers (PBDTsTh-FBT and PBDTsPh-FBT) with strong aggregation properties can blend well with roughly spherical PC 71 BM, while amorphous polymers (PBDTsThPh-BDD and PBDTsPhPh-BDD) with long and rigid aryl rings show good miscibility with elongated ITIC, and finally, both devices exhibit excellent power conversion efficiencies over 10%. Thus, it clearly shows that the asymmetric BDT unit is an excellent donor building block to construct highly efficient photovoltaic polymers. Meanwhile, this work demonstrates that it is not necessary that high-performance fullerene-free polymer solar cells (PSCs) require highly ordered microstructures in the blending films, different from the fullerene-based PSCs. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Development and performance evaluation of fiber reinforced polymer bridge.

DOT National Transportation Integrated Search

2014-03-01

Fiber reinforced polymers (FRP) have become more popular construction materials in the last decade due to the reduction of : material costs. The installation and performance evaluation of the first FRP-wrapped balsa wood bridge in Louisiana is descri...

Novel high-performance scattering materials for use in energy-saving light fittings and skylights based on polymer pigmented with polymer

NASA Astrophysics Data System (ADS)

Smith, Geoffrey B.; Earp, Alan; Franklin, Jim B.; McCredie, Geoffrey

2001-11-01

Simple quantitative performance criteria are developed for translucent materials in terms of hemispherical visible transmittance, and angular spread of transmitted luminance using a half angle. Criteria are linked to applications in luminaires and skylights with emphasis on maximising visible throughput while minimising glare. These basic criteria are also extended to angle of incidence changes which are substantial. Example data is provided showing that acrylic pigmented with spherical polymer particles can have total hemispherical transmittance with weak thickness dependence, which is better than clear sheet, while the spread of transmitted light is quite thickness-sensitive and occurs over wider angles than inorganic pigments. This combination means significantly fewer lamps can achieve specified lux levels with low glare, and smaller skylights can provide higher, more uniform daylight illuminance.

High-Performance Polymer Solar Cells Based on a Wide-Bandgap Polymer Containing Pyrrolo[3,4- f ]benzotriazole-5,7-dione with a Power Conversion Efficiency of 8.63%

DOE PAGES

Lan, Liuyuan; Chen, Zhiming; Hu, Qin; ...

2016-04-25

In article 1600032, an efficient new wide-bandgap polymer based on a novel moiety of pyrrolo[3,4-f]benzotriazole-5,7-dione (TZBI) is developed by Lei Ying, Feng Lui, Thomas P. Russel, Fei Huang, and co-workers. The new chemistry enables fine electronic structure tuning and solution-processed single-junction polymer solar cells provided a remarkable power conversion efficiency of 8.63%. Full electrical and structural characterization reveales that TZBI is a promising building block for the application in highly efficient organic photovoltaics.

The influence of polymer purification on photovoltaic device performance of a series of indacenodithiophene donor polymers.

PubMed

Ashraf, Raja Shahid; Schroeder, Bob C; Bronstein, Hugo A; Huang, Zhenggang; Thomas, Stuart; Kline, R Joseph; Brabec, Christoph J; Rannou, Patrice; Anthopoulos, Thomas D; Durrant, James R; McCulloch, Iain

2013-04-11

A series of low bandgap indacenodithiophene polymers is purified by recycling SEC in order to isolate narrow polydispersity fractions. This additional purification step is found to have a significant beneficial influence on the solar cell performance and the reasons for this performance increase are investigated. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of molecular properties on the performance of polymer light-emitting diodes

NASA Astrophysics Data System (ADS)

Ramos, Marta M. D.; Almeida, A. M.; Correia, Helena M. G.; Ribeiro, R. Mendes; Stoneham, A. M.

2004-11-01

The performance of a single layer polymer light-emitting diode depends on several interdependent factors, although recombination between electrons and holes within the polymer layer is believed to play an important role. Our aim is to carry out computer experiments in which bipolar charge carriers are injected in polymer networks made of poly(p-phenylene vinylene) chains randomly oriented. In these simulations, we follow the charge evolution in time from some initial state to the steady state. The intra-molecular properties of the polymer molecules obtained from self-consistent quantum molecular dynamics calculations are used in the mesoscopic model. The purpose of the present work is to clarify the effects of intra-molecular charge mobility and energy disorder on recombination efficiency. In particular, we find that charge mobility along the polymer chains has a serious influence on recombination within the polymer layer. Our results also show that energy disorder due to differences in ionization potential and electron affinity of neighbouring molecules affects mainly recombinations that occur near the electrodes at polymer chains parallel to them.

Vitamin D-restricted high-fat diet down-regulates expression of intestinal alkaline phosphatase isozymes in ovariectomized rats.

PubMed

Nakaoka, Kanae; Yamada, Asako; Noda, Seiko; Goseki-Sone, Masae

2018-05-01

Intestinal alkaline phosphatase (IAP) is expressed at a high concentration in the brush border membrane of intestinal epithelial cells. Intestinal alkaline phosphatase controls bacterial endotoxin-induced inflammation by dephosphorylating lipopolysaccharide and is a gut mucosal defense factor. Previously, we reported that IAP activity in the duodenum was significantly decreased in male rats receiving a high-fat diet with vitamin D restriction. Here, we tested the hypothesis that IAP is also regulated by a vitamin D-restricted high-fat diet in an animal model of menopause. Twenty-four female rats were ovariectomized (OVX), and another 6 female rats were sham operated. The OVX rats were divided into 4 groups and fed experimental diets: a basic control diet, a basic control diet with vitamin D restriction, a high-fat diet, and a high-fat diet with vitamin D restriction. After 28days of the experimental diets, the vitamin D-restricted high-fat diet decreased alkaline phosphatase activity in the duodenum of the OVX groups. The vitamin D-restricted high-fat diet down-regulated mRNA expressions of IAP isozymes in the duodenum of the OVX groups. These findings support the hypothesis that the expression of IAP is suppressed by a vitamin D-restricted high-fat diet in OVX rats. An adequate vitamin D intake and prevention of low vitamin D levels may be important for IAP expression in gut homeostasis. Copyright © 2018 Elsevier Inc. All rights reserved.

Nitrogen-Superdoped 3D Graphene Networks for High-Performance Supercapacitors.

PubMed

Zhang, Weili; Xu, Chuan; Ma, Chaoqun; Li, Guoxian; Wang, Yuzuo; Zhang, Kaiyu; Li, Feng; Liu, Chang; Cheng, Hui-Ming; Du, Youwei; Tang, Nujiang; Ren, Wencai

2017-09-01

An N-superdoped 3D graphene network structure with an N-doping level up to 15.8 at% for high-performance supercapacitor is designed and synthesized, in which the graphene foam with high conductivity acts as skeleton and nested with N-superdoped reduced graphene oxide arogels. This material shows a highly conductive interconnected 3D porous structure (3.33 S cm -1 ), large surface area (583 m 2 g -1 ), low internal resistance (0.4 Ω), good wettability, and a great number of active sites. Because of the multiple synergistic effects of these features, the supercapacitors based on this material show a remarkably excellent electrochemical behavior with a high specific capacitance (of up to 380, 332, and 245 F g -1 in alkaline, acidic, and neutral electrolytes measured in three-electrode configuration, respectively, 297 F g -1 in alkaline electrolytes measured in two-electrode configuration), good rate capability, excellent cycling stability (93.5% retention after 4600 cycles), and low internal resistance (0.4 Ω), resulting in high power density with proper high energy density. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dielectric breakdown in silica-amorphous polymer nanocomposite films: the role of the polymer matrix.

PubMed

Grabowski, Christopher A; Fillery, Scott P; Westing, Nicholas M; Chi, Changzai; Meth, Jeffrey S; Durstock, Michael F; Vaia, Richard A

2013-06-26

The ultimate energy storage performance of an electrostatic capacitor is determined by the dielectric characteristics of the material separating its conductive electrodes. Polymers are commonly employed due to their processability and high breakdown strength; however, demands for higher energy storage have encouraged investigations of ceramic-polymer composites. Maintaining dielectric strength, and thus minimizing flaw size and heterogeneities, has focused development toward nanocomposite (NC) films; but results lack consistency, potentially due to variations in polymer purity, nanoparticle surface treatments, nanoparticle size, and film morphology. To experimentally establish the dominant factors in broad structure-performance relationships, we compare the dielectric properties for four high-purity amorphous polymer films (polymethyl methacrylate, polystyrene, polyimide, and poly-4-vinylpyridine) incorporating uniformly dispersed silica colloids (up to 45% v/v). Factors known to contribute to premature breakdown-field exclusion and agglomeration-have been mitigated in this experiment to focus on what impact the polymer and polymer-nanoparticle interactions have on breakdown. Our findings indicate that adding colloidal silica to higher breakdown strength amorphous polymers (polymethyl methacrylate and polyimide) causes a reduction in dielectric strength as compared to the neat polymer. Alternatively, low breakdown strength amorphous polymers (poly-4-vinylpyridine and especially polystyrene) with comparable silica dispersion show similar or even improved breakdown strength for 7.5-15% v/v silica. At ∼15% v/v or greater silica content, all the polymer NC films exhibit breakdown at similar electric fields, implying that at these loadings failure becomes independent of polymer matrix and is dominated by silica.

Conducting Polymer-Based Nanohybrid Transducers: A Potential Route to High Sensitivity and Selectivity Sensors

PubMed Central

Park, Seon Joo; Kwon, Oh Seok; Lee, Ji Eun; Jang, Jyongsik; Yoon, Hyeonseok

2014-01-01

The development of novel sensing materials provides good opportunities to realize previously unachievable sensor performance. In this review, conducting polymer-based nanohybrids are highlighted as innovative transducers for high-performance chemical and biological sensing devices. Synthetic strategies of the nanohybrids are categorized into four groups: (1) impregnation, followed by reduction; (2) concurrent redox reactions; (3) electrochemical deposition; (4) seeding approach. Nanocale hybridization of conducting polymers with inorganic components can lead to improved sorption, catalytic reaction and/or transport behavior of the material systems. The nanohybrids have thus been used to detect nerve agents, toxic gases, volatile organic compounds, glucose, dopamine, and DNA. Given further advances in nanohybrids synthesis, it is expected that sensor technology will also evolve, especially in terms of sensitivity and selectivity. PMID:24561406

Amine quinone polyurethane polymers for improved performance in advanced particulate media

NASA Astrophysics Data System (ADS)

Warren, G. W.; Sharma, Rahul; Nikles, D. E.; Hu, Y.; Street, S. C.

1999-03-01

The magnetic layer used in commercial, high density, metal particle recording media consists of sub-micron sized Fe particles suspended in a polyurethane polymer binder. New amine-quinone polymers, AQPU15 and AQPU100, have been developed for improving corrosion resistance of the particles. A fundamental study of the nature of the AQ polymer/metal oxide interface and its relationship to corrosion resistance is reported. Electrochemical impedance spectroscopy was used to evaluate corrosion behavior of Fe substrates coated with two different thicknesses of each polymer. The extent of corrosion of Fe particles coated with AQ polymers was also measured via the loss in MS with time of immersion in an acid solution. AQ coated particles showed significant improvement in corrosion resistance. FTIR-RA and XPS data show an interaction between AQM14A, a simple model for a portion of the polymer, and metal (Fe, Cu, Al) surfaces which occurs through the π system of the AQ functional group.

Development and characterization of direct ethanol fuel cells using alkaline anion-exchange membranes

NASA Astrophysics Data System (ADS)

Lim, Peck Cheng

2009-08-01

Alkaline membrane fuel cell (AMFC) is a relatively new fuel cell technology that is generating considerable interests. It offers the electrocatalytic advantages of conventional alkaline fuel cells, and the manufacturing and cost advantages of solid polymer electrolyte fuel cells. This project was carried out to develop and characterize high performance membrane electrode assemblies (MEAs) for all-solid-state AMFCs. The primary fuel of interests is ethanol, but hydrogen was used in the development stages to facilitate the diagnostic and evaluation of the fuel cell performance. In the preliminary investigation, AMFC was assembled using off-the-shelf electrodes and anion-exchange membrane (AEM). It was found that the performance of AMFC operating on ethanol fuel was limited by a large high-frequency resistance (HFR) value. The advantage of using non-toxic ethanol fuel was also compromised by the need to add hydrazine and potassium hydroxide to the fuel blend. Subsequently, a high performance MEA was developed for an all-solid-state AMFC, in which liquid electrolyte or other additives were not required during the operation of the fuel cell. Ionomer was incorporated in the formulation of catalyst ink, and the catalyst ink was directly coated on the anion-exchange membrane (AEM). An ionomer content of 20 wt.% was found to be the optimum amount required in the catalyst layers. It was demonstrated that the AMFC generated a maximum power density of 365 mW/cm2 and 213 mW/cm 2 with the use of hydrogen/oxygen and hydrogen/pure air, respectively. The performance of the AMFC was also found to be influenced by exposure to carbon dioxide in the air. Hence, the CCMs were pre-treated in potassium hydroxide solution and pure oxygen was used to condition the fuel cell to maximize the power output from the AMFCs. Although satisfactory performance was demonstrated in the AMFC, its stability during cell operation remains a major issue. The poor stability was attributed to degradation of

Magnetic molecularly imprinted polymers for the determination of β-agonist residues in milk by ultra high performance liquid chromatography with tandem mass spectrometry.

PubMed

Liu, Hongcheng; Lin, Xin; Lin, Tao; Zhang, Yulong; Luo, Yinglan; Li, Qiwan

2016-09-01

A simple, accurate, and highly sensitive analytical method was developed in this study for the determination of nine β-agonists in milk. In this method, a new magnetic adsorbent of molecularly imprinted polymers/magnetic nanoparticles prepared by simple physical blending was adopted, which enabled magnetic solid-phase extraction. Thus, the resultant material can be separated from the solvent rapidly and conveniently by a magnet. Two kinds of molecularly imprinted polymer/magnetic nanoparticles materials were fabricated, and the characteristics of materials such as the ratio, pH, amount, desorption, and regeneration were investigated. The analytes were quantified by ultra high performance liquid chromatography coupled to an electrospray ionization tandem mass spectrometer operating in multiple reaction monitoring modes. The detection limit of the method was 0.003-0.3 μg/L, and the detection capability was 0.01-0.3 μg/L. The recoveries of these compounds were 65.7-114% at three spiked levels. Reproducibility represented by relative standard deviation was 11.2% or less. The method was successfully applied to the screening of real samples obtained from local markets and confirmation of the suspected target analytes. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The relationship between surface tension and the industrial performance of water-soluble polymers prepared from acid hydrolysis lignin, a saccharification by-product from woody materials.

PubMed

Matsushita, Yasuyuki; Imai, Masanori; Iwatsuki, Ayuko; Fukushima, Kazuhiko

2008-05-01

In this study, water-soluble anionic and cationic polymers were prepared from sulfuric acid lignin (SAL), an acid hydrolysis lignin, and the relationship between the surface tension of these polymers and industrial performance was examined. The SAL was phenolized (P-SAL) to enhance its solubility and reactivity. Sulfonation and the Mannich reaction with aminocarboxylic acids produced water-soluble anionic polymers and high-dispersibility gypsum paste. The dispersing efficiency increased as the surface tension decreased, suggesting that the fluidity of the gypsum paste increased with the polymer adsorption on the gypsum particle surface. Water-soluble cationic polymers were prepared using the Mannich reaction with dimethylamine. The cationic polymers showed high sizing efficiency under neutral papermaking conditions; the sizing efficiency increased with the surface tension. This suggests that the polymer with high hydrophilicity spread in the water and readily adhered to the pulp surface and the rosin, showing good retention.

Highly nitrogen-doped carbon capsules: scalable preparation and high-performance applications in fuel cells and lithium ion batteries.